240
t NASA Contractor Report 185129 Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup Technology, Inc. Lewis Research Center Group Brook Park, Ohio May 1990 Prepared for Lewis Research Center Under Contract NAS3-25266 National Aeronautics and Space Administration ( NA?;A-C"-'- ! _:_5 .L2 _ ) F inlet IC_ ACCPETION P#;:{']iCIIUN C.O{)_ (Lt-WIC£) f _chn o1 ..... , + (Sv-_r!ru# ojy/) 9__ -_ n,,: _>nr " CSCt OIS G3/oi Ngo-z0943 5 7Y/_ https://ntrs.nasa.gov/search.jsp?R=19900011627 2020-05-29T15:23:26+00:00Z

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Page 1: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

t

NASA Contractor Report 185129

Users Manual for the NASA LewisIce Accretion Prediction

Code (LEWICE)

Gary A. Ruff and Brian M. Berkowitz

Sverdrup Technology, Inc.Lewis Research Center Group

Brook Park, Ohio

May 1990

Prepared forLewis Research Center

Under Contract NAS3-25266

National Aeronautics andSpace Administration

( NA?;A-C"-'- ! _:_5.L2 _ )

F inletIC_ ACCPETION P#;:{']iCIIUN C.O{)_ (Lt-WIC£)

f _chn o 1

....., + (Sv-_r!ru# ojy/) 9__ -_

n,,: _>nr" CSCt OIS

G3/oi

Ngo-z0943

5 7Y/_

https://ntrs.nasa.gov/search.jsp?R=19900011627 2020-05-29T15:23:26+00:00Z

Page 2: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

TABLE OF CONTENTS

LIST OF SYMBOLS

PAGE

V

SUMMARY viii

1.0 BACKGROUND

2.0 INTRODUCTION

I

3

3.0 DISCUSSION OF THE ICE ACCRETION PROCESS

3.1 Ice Accretion Characteristics

3.2 Description of the Physical Model

6

6

7

4.0 METHODOLOGY

4.1 Calculation of the Flow Field

4.2 Calculation of the Droplet Impingement Characteristics

4.3 Calculation of the Thermodynamic Characteristics

4.4 Calculation of the Iced Geometry

4.5 General Computational Procedure

11

11

12

22

25

27

5.0

6.0

LEWICE INPUT

5.1 Input Format

5.2 User's Guide to Input Format

5.3 Interactive Input

LEWICE OUTPUT

6.1 Printed Output

6.2 Graphical Output

38

38

46

54

62

62

68

7.0 EXAMPLE CASES 88

7.1 Example 1: Glaze Icing on a NACA 0012 Airfoil, a = 0.0 ° 88

7.2 Example 2: Glaze Icing on a NACA 0012 Airfoil, a = 4.0 o 91

7.3 Example 3: Glaze Icing on a NACA 0012 Airfoil, a = 0.0 ° 96

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7.4Example 4: Specification of a Droplet Size Distribution

7.5 Example 5: Thermal Anti-icing

8.0 PROGRAMMING AIDS

8.1 Description of Subroutines

8.2 Diagnostic and Error Messages

8.3 Potential Flow Calculations

8.4 Particle Trajectory Calculations

8.5 Thermodynamic and Ice Accretion Calculations

8.6 COMMON Blocks and Work Files

8.7 Size of the Code

8.8 Execution Times

8.9 Getting LEWICE Operational

LIST OF REFERENCES

APPENDICES

A. Derivation of the Icing Energy Equation

B. Integral Boundary Layer Method on an Iced Surface

C. Flow Field Corrections

D. Complete Input to the Potential Flow Code ($24Y)

E. Calculation of the Local Edge Velocities

F. Empirical Relationship for the Equivalent Sand-Grain

Roughness Height

97

100

146

146

146

146

147

148

149

149

157

157

158

160

171

188

204

216

220

ii

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ACKNOWLEDGEMENTS

The development of LEWICE leading to the publication of this user

manual has involved many researchers, each of whom made improvements

to the code and/or comparisons with experimental data. All of these efforts

contributed to the version of LEWICE described in this manual. Special

recognition should go to Dr. Robert J. Shaw of NASA Lewis Research

Center and Dr. James T. Riley of the Federal Aviation Administration

Technical Center for providing funding over the years, and for their constant

support of the project.

Below is the list of people who have contributed to the development

of the current version of LEWICE. My apologies to any who, through my

negligence and ignorance, have been excluded from the list.

University of Dayton Research Institute

Charles D. MacArthur

Patrick A. Haines

John L. Keller

Dr. William Hankey

NASA Lewis Research Center

James E. Newton

Nicola M. Juhaz

John M. Prather

Loretta A. Austin

Denise Deems

Sverdrup TechnologT_. Inc.

Susan Zeleznik

Angela Quealy

*****************************************************************

* By participating in the generation of the computer codes or other *

* test data reported herein, NASA makes no assurances that said *

* code or other data is complete, accurate, or sufficient for purposes *

* of assuring safety of operation of aircraft. ******************************************************************

iii

Page 5: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

List Of Symbols

A

At

At

AB

C

Cd

cl

el

Cm

Cp

C!CVF

d_

d_

D

E=

f

FRL

gH

h,

i

L,k°

L

L!

L_

LWC

M

m

tT_H

r_

r_ u

rt i

Characteristic area

Accumulation parameter

Modified accumulation parameter

Mass transfer driving potential

Characteristic length

Drag coefficient

Skin friction coefficient

Lift coefficient

pitching moment coefficient

Pressure coefficient, also specific heat, J/kg

Cunningham correction factor

Control volume fraction

Ice thickness, m

Mass median droplet diameter,/zm

Drag force, N

Total collection efficiency

Freezing fraction

Flight reference line

Mass transfer coefficient, kg-K/J

Projected height, m

Convective heat transfer coefficient, W/m2/K

Enthalpy, J/kg

Moment of inertia relative to z axis

Equivalent sand-grain roughness, m

Lift force, N

Heat of fusion, J/kg

Heat of vaporization, J/kg

Liquid water content, g/m 3

Much number; moment of aerodynamic forces

Mass, kg

Mass per unit area, kg/m 2

Mass flow rate, kg/sec

Mass flux, kg/rn _ /sec

Mass fraction of liquid water for droplet diameter i

PRECEDING PAGE BLANK NOT FILMED

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N

P

Pr

qc

qk

Tc

Re

Rek

Re_

S

Sc

St

Stk

T

t

At

V

v:vkX

y

/t0

V

P

E

6

Subscripts

a

&w

c

d

Number of droplet sizes defining a droplet distribution

Number of points describing geometry

Pressure, Pa

Prandtl number

Convective heat flux, W/rn _

Conductive heat flux, W/rn 2

Recovery factor

Freestream Reynolds number

Laminar/turbulent transition Reynolds number

Droplet Reynolds number based on V_

Surface length, m; surface length increment, m

Schmidt number

Stanton number

Roughness Stanton number

Temperature, °K

Icing time, sec

Icing time increment, sec

Velocity, m/8

Volume fraction of LWC

Velocity at y : ko, rn/s

x-coordinate

y-coordinate

Angle of attack, degrees

Local collection efficiency

Pitch angle, degrees; momenteum thickness, m

Viscosity, N s / rn 2

Density, g/m s

Shear stress, N/rn 2

Particle trajectory convergence criteria

Boundary layer thickness, m

Thermal conductivity of air, W/rn _o K

Air

Adiabatic wall

Critical; convection

Droplet

vi

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e

i

(i)(i-I)1

L

Pr

Fin

7"ou t

S

sur

T

t

tr

U

t_

W

X

y

0

O0

G

Superscripts

Evaporation; condition at the edge of the boundary layer

Ice

Control volume

Preceding control volume

Lower surface; laminar

Local condition; condition at the edge of the boundary layer

Particle

Runback water

Runback into control volume

Runback out of control volume

Static condition

Surface condition

Total condition

Turbulent

Laminar to turbulent transition

Upper surface

Vapor

Liquid water

Magnitude of the vector in the x-direction

Magnitude of the vector in the y-direction

Initial

Freestream conditions

Shear

Vector quantity

Derivative with respect to time

Non-dimensionalized parameter

vii

Page 8: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

SUMMARY

LEWICE is an iceaccretion prediction code that applies a time-stepping

procedure to calculate the shape of an ice accretion. The potential flow field

is calculated in LEWICE using the Douglas Hess-Smith 2-D panel code

($24Y). This potential flow field is then used to calculate the trajectories

of particles and the impingment points on the body. These calculations

are performed to determine the distribution of liquid water impinging on

the body, which then serves as input to the icing thermodynamic code.

The icing thermodynamic model is based on the work of Messinger, but

contains several major modifications and improvements. This model is

used to calculate the ice growth rate at each point on the surface of the

geometry. By specifying an icing time increment, the ice growth rate can

be interpreted as an ice thickness which is added to the body, resulting in

the generation of new coordinates. This procedure is repeated, beginning

with the potential flow calculations, until the desired icing time is reached.

The operation of LEWICE is illustrated through the use of five ex-

amples. These examples are representative of the types of applications

expected for LEWICE. All input and output is discussed, along with many

of the diagnostic messages contained in the code. Several error conditions

that may occur in the code for certain icing conditions are identified, and

a course of action is recommended.

LEWICE has been used to calculate a variety of ice shapes, but should

still be considered a research code. The code should be exercised further to

identify any shortcomings and inadequacies. Any modifications identified

as a result of these cases, or of additional experimental results, should be

incorporated into the model. Using it as a test bed for improvements to

the ice accretion model is one important application of LEWICE.

viii

Page 9: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

Chapter 1

BACKGROUND

The evaluation of both commercial and military flight systems in icing

conditions has become important in the design and certification phases

of system development. These systems have been evaluated in flight in

natural icing, in a simulated cloud produced by a leading aircraft, and in

ground test facilities. All icing testing is relatively expensive, and each test

technique, i.e., flight or ground testing, has operational limitations which

limit the range of icing conditions that can be evaluated. It would benefit

the aircraft or flight system manufacturer to be able to analytically predict

the performance of the system for a range of icing conditions.

This first step in the prediction of the performance characteristics is

the determination of the location, size, and shape of the ice that will form.

An analytical ice accretion model would allow the evaluation of a wide

range of proposed test conditions to identify those that will be most critical

to the flight system. This could substantially reduce the amount of test

time required to adequately evaluate a system and increase the quality

and confidence level of the final evaluation. The analytically predicted

ice accretion could also serve as the input to an advanced aerodynamic or

system performance code to allow more complete evaluation in the design

phases of the system. For these reasons, several analytical ice accretion

prediction methods have been developed by various investigators.

The most well-known axe those of Ackley and Templeton 1, Lowzowski 2,

Hankey and Kirchner a, and Cansdale and Gent 4. All apply essentially the

same physical model of the ice accretion process but differ in the manner

that the surface properties, for example, the local collection efficiency and

convective heat transfer coefficient, are calculated and allowed to vary over

the surface. Also, several of these models were restricted to the simulation

of the icing of a cylinder. One of the major inadequacies of these moclels

is that they do not account for any of the time-dependent aspects of the

ice accretion process. In general, the ice accretion rate is calculated as

a function of position on the airfoil and projected at a constant rate to

approximate a finite growth over a prescribed period of time. Therefore,

1

Page 10: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

any sensitivity of the ice accretion process to the changing iced airfoil shapeis not included.

The purpose of the current study was to develop a time-dependent, an-

alytical model of the ice accretion process that could be used to predict the

shape of the ice accretion that would form on an arbitrary two-dimensional

geometry when exposed to icing conditions. The development of the com-

puter code (LEWICE) was begun by the University of Dayton Research

Institute (UDRI) under contract to NASA Lewis Research Center. The

results of this study are described in Reference 5. Development of the code

was then continued at the NASA Lewis Research Center under NASA fund-

ing until October 1984 when funding by the Federal Aviation Administra-

tion (FAA) was begun. This document describes the results of the current

development effort and contains the information necessary to apply the ice

accretion prediction method to practical icing problems.

2

Page 11: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

Chapter 2

INTRODUCTION

The computer code, LEWICE, embodies an analytical ice accretion model

that evaluates the thermodynamics of the freezing process that occurs when

supercooled droplets impinge on a body. The atmospheric parameters of

temperature, pressure, and velocity, and the meteorological parameters of

liquid water content (LWC), droplet diameter, and relative humidity are

specified and used to determine the shape of the ice accretion. The sur-

face of the clean (uniced) geometry is defined by segments joining a set

of discrete body coordinates (Fig. 2.1). The code consists of three major

modules. They are 1) the flow field calculation, 2) the particle trajectory

and impingement calculation, and 3) the thermodynamic and ice accretion

calculation. Each of these modules will be discussed in detail in following

sections.

LEWICE differs from other ice accretion prediction codes 1-4 because

it applies a time-stepping procedure to "grow" the ice accretion. Initially,

the flow field and droplet impingement characteristics are determined for

the clean geometry. The ice growth rate on each segment defining the

surface is then determined by applying the thermodynamic model. When

a time increment is specified, this growth rate can be interpreted as an ice

thickness and the body coordinates are adjusted to account for the accreted

ice. This procedure is repeated, beginning with the calculation of the flow

field about the iced geometry, then continued until the desired icing time

has been reached. The application of this time-stepping procedure to the

prediction of an ice accretion shape will be discussed in greater detail in

following chapters.

Ice accretion shapes for cylinders and several single-element airfoils have

been calculated using this computer code. The calculated results have been

compared to experimental ice accretion shapes obtained both in flight and

in the Icing Research Tunnel at NASA Lewis Research Center. In general,

the comparisons have been encouraging but inconsistent. Ice shapes for

some conditions are well predicted, while for others there is little similarity

between the predicted accretion and that obtained by experiment. Unfor-

3

Page 12: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

tunately, the poorer predictions do not consistently occur in only one type

of icing condition such as glaze or rime icing, on a specific type of airfoil, or

in comparisons with results from a specific facility. There are many possible

explanations for this behavior including inaccurate modeling of the accre-

tion process, occasional errors in setting test conditions, and overextending

the computer code into conditions where the assumptions, such as potential

flow, do not apply. The known limitations will be addressed throughout

this user's manual.

The manual begins with a discussion of the ice accretion process to

identify the requirements of an ice accretion prediction methodology. The

major components of the code and the mathematical models applied in

each are then discussed. The input and output to the code are described,

followed by the presentation of several sample cases, which illustrate various

aspects of the code. The manual concludes with a summary of the current

resultsand shortcomings of the method.

Areas requiring additional development are identifiedand discussed in

the Appendices (A through F).

4

Page 13: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

+y'

STAGNATIONPOINT

(S = 0.0)-_,..

NODES/ix.

// | \X\

I I \\I I \I I \

+X

Figure 2.1: Geometry defined by segments joining body coordinates

5

Page 14: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

Chapter 3

DICUSSION OF THE ICE ACCRETION PROCESS

The model of the ice accretion process applied in LEWICE is presented in

this chapter, beginning with a discussion of some of the general character-

istics of ice accretion shapes, mad followed by a description of the physical

model of the ice accretion process from which a mathematical model must

be formulated.

3.1 Ice Accretion Characteristics

Before discussing the physical model of the ice accretion process, it is nec-

essary to define some of the terms used in such a discussion.

Ice may form on the forward facing surfaces of an aircraft flying through

clouds composed of supercooled water droplets. The type and shape of ice

that forms are functions of the atmospheric parameters of velocity, pres-

sure, and temperature, and the meteorological parameters of liquid water

content, droplet diameter, and icing time.

Ice shapes are generally classified as glaze, mixed, and rime accretions.

Rime ice is milky white and opaque, and will be denoted in the ice accretion

profiles in this report by shading as shown in Figure 3.1a. Glaze ice is

generally clear and is characterized by the presence of larger protuberances,

commonly known as glaze horns, as shown in Figure 3.1b. A mixed ice

accretion will have some of the characteristics of both glaze and rime ice

accretions. As shown in Figure 3.1c, the center portion of a mixed ice

accretion will have the characteristics of glaze ice accretion. This glaze

center will be surrounded by rime ice accretions, commonly called rime

feathers because of their thin, feather-like shape and delicate structure.

The type of ice that will be formed is dependent on the atmospheric

and meteorological conditions identified in the preceding paragraph. Pre-

dicting the type and shape of the ice accretion that will be formed for a

specified set of icing conditions is difficult because of the complex interac-

tions between the atmospheric and meteorological parameters. Typically,

rime ice is formed at lower temperatures, velocities, and LWC than glaze

6

Page 15: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

ice. An example of the transition from glaze to rime ice as the total temper-ature is lowered is shown in Figure 3.2. At the warmest total temperature,

Tr - -2.0C, the accretion is composed exclusively of glaze ice. As the tem-

perature decreases, areas of rime ice begin to form near the impingement

limits. As the temperature decreases further, these rime portions increase

in size until the accretion is composed solely of rime ice. The extent of icing

and the locations at which ice forms on a surface are largely dictated by the

size of the droplets impinging on the surface. For a given icing condition,

and in the absence of ice shedding, the size of the accretion depends on

the length of time ice is allowed to accrete. The general effects of temper-

ature, droplet size, LWC, and angle of attack on ice shapes formed on a

NACA 0012 airfoil in the NASA Lewis Icing Research Tunnel (IRT) are

documented in Reference 6.

3.2 Description of the Physical Model

An understanding of the interactions between these parameters is required

to predict the shape of an ice accretion that will be formed at a specified

set of icing conditions. To develop this fundamental understanding, it is

necessary to examine the physical model of the ice accretion process.

A model of the ice accretion process was first presented by Tribus _ and

developed further by Messinger s. While many studies have been done to

understand various aspects of the ice accretion process, the original physical

model has been applied relatively unchanged. Recent close-up movies and

photographs of the ice accretion process made at the NASA Lewis Research

Center 9 have increased our understanding of the process and indicated that

modifications to the physical model may be necessary. Conclusions drawn

from the observations are included in the following discussion of the ice

accretion process, and differences from the previous model are highlighted.

The ice accretion process is characterized by the presence of supercooled

droplets entrained in the flow about a body. These droplets follow trajecto-

ries that will cause them to either be carried past or impinge upon a body.

Upon impact with a clean surface, the droplets coalesce into larger surface

drops under the effects of surface tension and flow along the surface as dic-

tated by the airflow along the surface of the body. These surface drops will

then either freeze on the surface or be shed from the surface because of the

7

Page 16: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

aerodynamic forces on the drop. The ice accretions formed by this initial

freezing form a rough surface which enhances the convective heat transfer

and local collection efficiency of the surface, and therefore allows the ice

accretion process to continue.

The type of ice that will form for a given set of conditions is determined

primarily by the rate at which the freezing process occurs. For example, if

the conditions are such that the droplets freeze rapidly, there is essentially

no initial coalescing and flowing of the droplets. Instead, they freeze on

impact and form the characteristic rime ice a_:cretions. These accretions

are opaque and milky white in color because of the presence of air bubbles

that are trapped in the structure during the rapid freezing process. As the

rate of the freezing process decreases, the droplets begin to coalesce and

flow on the surface. Upon freezing, these larger surface droplets form sur-

face roughness elements which tend to enhance the convective heat transfer

and local collection efficiency characteristics, which, in turn, enhance the

continuing growth of the ice accretion in this region. These local areas

of enhanced ice growth are, therefore, the beginnings of the characteristic

horns found on mixed and glaze ice accretions. As the freezing rate de-

creases further, the drops flow further along the surface of the body before

freezing, thus moving the regions of enhanced ice growth away from the

stagnation point. This, in turn, causes the horns of the accretion to move

further apart and forms the familiar glaze ice accretions. As the rate of the

freezing process decreases, less air is trapped within the ice structure and

the ice gradually becomes clearer until it is essentially transparent, as in

glaze ice.

This description of the ice azcretion process has identified four basic

areas or processes that must be modeled in order to predict the shape of an

ice accretion that will form on a body for a specified set of icing conditions.

These areas are 1) the flow field about the body, 2) the droplet trajectory

and impingement characteristics on the body, 3) the thermodynamics of

the freezing process, and 4) the accumulation of ice on the surface of the

body. To analytically predict a_n ice accretion shape, a mathematical model

of each of these physical processes must be developed. Each of these areas

will be discussed in subsequent sections to identify the methods used in the

ice accretion prediction code, LEWICE.

Page 17: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

ICING CONDITIONS

A __.8 C__CYLINDER DI_U_, IN. 1.0 2.0 1.0

PS" P$|A 1_.2 12.2 lq.2

Ts, OF -5.0 21.1 5Vo fps 200 367 qo0aM, p_ _ 20 22 15

LWC, g/_ O. G O. 35 O. 53

X, MZX 8.0 3;0.6 6.8

SHADEDPORTIONSDENOTERIMI" ICE\

\\

a. Rime ice accretion, f : 1.0

GLAZE HORNS

b. Glaze ice accretion, f = 0.15

RIME FEATHERS-._

c. Mixed ice accretion, f = 0.53

Figure 3.1: Examples of ice accretions formed at various atmospheric and

meteorological conditions

9

Page 18: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

OR1GINA[ PAGE IS

OF POOR QUALITY

,f_ ALLGLAZE ICE

(A) TO(AL TEI'IP_RATUR_L,-2 °C (B) TOTAL Tt-/_°f.RATURE, -8 oc

(MAGNATION FREEZING FRACTION, 0.22). (STAGNATION FREEZING FRACTION, 0.32).

(C) TOTAL TEMPERATURE,-15 °C

(STAGNATION FRE£ZING FRACTION, O.SS).

STREAKS

(D) TOTAL TLPPERATURE, -18 °C

(STAGNATION FREEZING FRACTION, 0.55).

(E) TOTAL TIE/_RATURIE, -20 °C

(STAIglATIOR FREEZIII6 FRACTION,

WHITE RI/'_

ICE IS OPAQUE:BLACKMIEN

BACKLIGHTED

ALL

RIPE

(F) TOTAL TEMPE,RATURE, -26 °C

(STAGNATION FRE£Z|NG FRACTION, 0.9).

Figure 3.2: Effect of temperature on the ice accretion shape. Thin ice

samples removed from the airfoil and backlighted; Airspeed, 20gkm/hr;

LWC, 1.3g/mS; DVM, 20m; Time, 8rain; Airfoil, 0.53m chord 0012 airfoil

at 4 ° angle.

10

Page 19: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

Chapter 4

METHODOLOGY

The phenomena that make up the ice accretion process have been identified

and now must be investigated in order to accurately predict the shape of

an ice accretion that will form on a body. These include the evaluation of

1) the flow field about the body,

2) the droplet trajectory and impingement characteristics,

3) the thermodynamics of the freezing process, and

4) the accumulation of the ice on the surface.

The computational methodology used to evaluate each of the above areas

is discussed in the following sections.

4.1 Calculation of the Flow Field

The application of a flow field calculation method to an ice accretion pre-

diction code requires that the method not only be able to calculate accurate

flow fields about clean geometries, but also around the irregular, convoluted

ice shapes that occur for many icing conditions. It is also desirable that the

computational time and memory requirements of the method be as small

as possible so that the use of the code is not limited to icing researchers

with large computer facilities.

The Douglas two-dimensional potential flow program developed by Hess

and Smith, described in Reference 10, meets these requirements, and is used

in the present study for calculating the flow field about the body. This pro-

gram uses a distribution of sources, sinks, and/or vortices along the body

surface to calculate the potential flow field. The body surface is represented

by an arbitrary number of straight line segments. In calculating the flow

field, contributions from all the sources, sinks, and/or vortices are summed.

The accuracy of this method was tested by comparing its predicted veloc-

ities and surface pressure coefficients with both analytical solutions and

11

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experimental data 1°. Excellent agreement was found. Similar comparisons

were performed at NASA Lewis and compared with pressure coefficient

data found in Reference 11. These comparisons, shown in Figures 4.1a-j,

show that the surface pressure coefficient is well predicted by the poten-

tial flow method for angles of attack up to approximately 11.0 degrees and

Mach numbers up to 0.50. These flow field limitations must be considered

when predicting ice accretion shapes at high Mach numbers or high angles

of attack.

Only limited details of the methodology applied in the potential flow

program are provided in this manual since the purpose of this study was to

develop an analytical ice accretion prediction program. However, sufficient

description of the input as well as subroutines are supplied to allow the user

to become familiar with the primary aspects and limitations of the code.

4.2 Calculation of the Droplet Impingement Characteristics

The algorithm applied in the current ice accretion model to calculate the

droplet trajectory and impingement characteristics was originally developed

by Frost, Chang, Shieh, and Kimble of FWG Associates under contract to

NASA Lewis 12-13.

This code was developed to calculate the trajectories and impingement

characteristics of arbitrarily-shaped particles, and although water droplets

are of primary concern when evaluating the ice accretion process, the gen-

erality has been retained in LEWICE. While much of this code has been

applied in its original form in the current study, there are significant changes

in many areas and, therefore, the current version of the code is discussed

in detail in this report.

4.2.1 Definitions

The primary droplet impingement characteristics that must be evaluated

by an ice accretion prediction code are the regions of droplet impingement

and the distribution of the mass of liquid on the surface of the body within

this impingement region.

The equations of particle motion, to be discussed in the following sec-

tion, are used to calculate droplet trajectories from far upstream to impinge-

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ment on the body and, if it occurs, the total and local collection efficiencies.

The total collection efficiency is defined as the ratio of the actual mass of

impinging water to the maximum value that would occur if the droplets

followed straight-line trajectories. Figure 4.2 illustrates that this definition

can be given in equation form as

E,,_ = I/o (1)H

where !t0 is the vertical distance between the droplet release points of the

upper and lower surface tangent trajectories. The local collection efficiency,

3, is also defined in Figure 4.2 and can be written in differential form as

dyo

(2)

It is related to the total collection efficiency by the equation

1 i s"= -- _ dsE,,, H

(3)

where s,, and sl are the upper and lower surface impingement limits, respec-

tively. The following sections will cover the methods applied to calculate

the variables discussed above.

4.2.2 Equations of Particle Motion

The motion of a particle is analyzed as a point mass particle that is acted

on by the potential flow field but which itself does not affect the flow.

The forces acting on the particle are considered to be those of lift, drag,

pitching moment, and gravity. Figure 4.3 shows the forces acting on the

particle and the velocity vectors relative to the motion of the particle.

The flight reference line (FRL) is not significant for a spherical particle;

however, for arbitrarily shaped particles, i.e., a snow flake, the FRL must

be defined relative to the lift, drag, and moment coefficient data available.

The equations of motion of an arbitrarily shaped particle are derived from

a force balance on a point mass, as shown in Figure 4.3, and are as follows:

rn_ = -D cos "_ - L sin 7 + rng sin a

mfl = -.D sin "1 + f_,cos "7 - mg cos a (4)

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where

"_= ta"- 1 _,,- v, (5)_p - V,

In Figure 4.3, note that the coordinate system used in LEWICE is fixed to

the leading edge of the clean airfoil.

For an airfoil at an angle of attack a, the coordinate system is at an

angle to the gravitational coordinate system. Therefore, the effect of gravity

must be accounted for in the equations for both lift and drag.

The flow field velocity components in the x and y directions, i.e., V_

and V_, respectively, are obtained from the potential flow program. The

aerodynamic drag and lift forces are defined as

p, V 2

= Cd_ Ap,_ p.____'vA, (6)

where Ap is a characteristic area of the particle, p_ is the density of air at

the position of the particle, and V is the particle velocity relative to the

flow field and defined as

V = V'(_, - vz)' + (0,- v,)' (7)

For arbitrarily shaped particles, the pitch angle, 0p, is required to eval-

uate the angle of attack ap, using the following equation

,,,,,= o,,- ,_ (8)

This motion is governed by the following equation

MI. (o)

where Iu is the moment of inertia of mass relative to the z axis. The

moment of aerodynamic forces acting on the particle is

p, V _

M = c,,_---_ Apdj, (10)

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where c,_ is the pitching moment coefficient which must also be specified

by the user.

The lift, drag, and pitching moment coefficients, cl, Cd, and c,_ respec-

tively, must be provided by the user for arbitrarily shaped particles. The

coefficient data is input to the program through subroutine COEFF and

should be functions of the particle angle of attack, as defined by Equation

8, and the particle Reynolds number based on the particle diameter, given

by the following equations:V dp

R,, - (11)/2

The diameter of the particle, d, and the kinematic viscosity of air, u, are

assumed constant along the trajectory of the particle.

Since water droplets are usually assumed to be rigid spheres in icing

studies, the only forces considered to be acting on the particle are those of

drag and gravity. The governing equations can therefore be simplified as

follows:

m_c = -D co8 "7 + rng sin a

= -5 si."7 - mg (12)

In this case, the drag force, D, is determined using a steady-state drag

coefficient for a sphere which is a function of the droplet Reynolds number,

Rep. Approximating droplets as rigid spheres is valid for drop radii less

than 500.0 microns 14. A valid drag law for spherical particles is built into

the computer program in subroutine COEFF.

For particles with diameters of less than 10 microns, the ratio of particlediameter to the mean distance between air molecules is small enough so that

molecular slip phenomena result in drag forces lower than those calculated

by the drag law used in LEWICE. The Cunningham correction factor, C/,

Reference 15, is therefore applied to correct the drag coefficient using the

following equation:Cd

cdJslip = -_I (13)

The values of C! are input by the user when necessary and are given in

Table 4.1. As shown in Table 4.1, this effect is small for particles with

diameters greater than 1.0 micron. Droplets this small would be included

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Table 4.1: Cunningham Correction Factor for Standard Air

d(u) C d(u) C

0.001 221.600 0.1 2.911

0.002 111.100 0.2 1.890

0.003 74.250 0.3 1.574

0.004 55.830 0.4 1.424

0.005 44.780 0.5 1.337

0.006 37.410 0.6 1.280

0.007 32.150 0.7 1.240

0.008 28.200 0.8 1.210

0.009 25.140 0.9 1.186

0.010 22.680 1.0 1.168

0.020 11.650 2.0 1.084

0.030 7.978 3.0 1.056

0.040 6.151 4.0 1.042

0.050 5.060 5.0 1.034

0.060 4.337 6.0 1.028

0.070 3.823 7.0 1.024

0.080 3.441 8.0 1.021

0.090 3.145 9.0 1.019

10.0 1.017

in an ice accretion prediction only in exceptional circumstances, such as

testing the limiting capabilities of an ice accretion code.

4.2.3 Method of Integration

The equations governing the motion of arbitrarily-shaped particles are asfollows:

dx dy 0 0 (14a - c)= d-7 = d-7 = dgi

-- cosT--- sinT+gsinadt m m

16

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- -- sin_+-- cos_-gcos adt m m

dO M

dt I_

(14d- f)

For spherical water droplets, Equations 14c and 14f are not applicable

and Equations 14d and 14e are simplified to result in the following four

equations:

dx

dt

dy

- cos "7 + g sindt m

-- = --- sin "7-g sindt m

(15)

These equations are integrated using the method of Gear developed for stiff

equations 16-17. The details of the subroutines that make up the integration

method, i.e., DIFSUB, DECOMP, SOLVE, and PEDERV, can be found in

Reference 16 and in COMMENT statements in the computer code. The

integration routine also requires that the equations to be integrated be

located in a subroutine named DIFFUN. This subroutine currently contains

Equations 14- 15.

4.2.4 Determination of Droplet Impingement

The calculation of the droplet trajectories is continued until the droplets

impinge upon the body or move out of range. This section describes the

procedure used to determine whether or not a droplet impacts the body

and, if so, the location of impingement. These calculations are controlled

by subroutine MODE.

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As previously discussed, the geometry is defined by segments joining a

discrete set of body coordinates as shown in Figure 2.1. A droplet is con-

sidered to impact the body when its trajectory intersects one of these body

segments. The current model does not take account of grazing collisions

or droplets that may impact the body so that they are re-introduced into

the flow by bouncing, splashing, etc. The impact algorithm, found in sub-

routine INTRST, sequentially sums the angles between lines drawn from

the particle position to adjacent points describing the closed curve of the

geometry, as shown in Figure 4.4. The summation starts with the angle

between lines drawn to the first and second points, continuing with the

angle between the lines to the second and third points, and so on, all the

way to the angle between lines drawn to the next to last and last points.

If the particle is outside the body, the sum of these angles will always be

zero. If the particle has crossed one of the body segments and lies inside

the body, the sum of the angles is 21r. If the particle lies directly on one of

the body segments, the summed angle will equal It.

A particle trajectory is calculated until the summed angles total 7r or 27r,

which indicates that the particle has impinged upon the body, or until the

particle passes outside of the pre-specified boundaries. The impact point

results from the intersection of the particle trajectory and the line con-

necting the adjacent ice shape points through which the particle trajectory

passed (Figure 4.5). The particular line segment through which the particle

passed is determined by first calculating the intersection of the line joining

the present and previous particle positions and the line formed by each of

the adjacent points that describe the body geometry, as shown in Figure

4.5. If the particle passed through a particular segment, the distance from

the intersection (impingement) point to the endpoints of the segments will

be less than the length of either the trajectory or body segments. Once the

body segment through which the particle passed and the intersection (im-

pingement) point have been determined, the surface distance, s, from the

stagnation point to the impingement point is determined by interpolation.

4.2.5 Calculation of the Local Collection Efficiency

The particle trajectories and impingement points, calculated as previously

described, are used to establish the relations between the particle's initial

position (x0, Y0) and the position where it impinges on the body surface,

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specified by the surface distance, s, which is the length along the bodysurface measuredfrom the stagnation point. The value of s is defined asnegative on the lower surfaceand positive on the upper surface.

The local collection efficiency is calculated by first calculating droplettrajectories and producing a plot of particle releasepoint, y0, vs. surface

impact distance, s, as shown in Figure 4.6. As was indicated by Equation

2, the local collection efficiency is a function of the surface distance and

can be determined by differentiating the curve shown in Figure 4.6 with

respect to s.

The derivative at the center of each body segment is calculated by first

determining the four y0 vs. s points whose s values are closest to the s

value of the body segment at which the local collection efficiency is desired,

as shown in Figure 4.6. These four points are then fit with a quadratic

polynomial using the method of least squares. The local collection efficiency

at the desired s location is determined by differentiating the polynomial.

The local collection efficiency is calculated in subroutine EFFICY, while

the curve fitting/differentiation procedure is found in subroutine TERP.

4.2.5.1 Local Collection Efficiency Calculation for Multidispersed

Particle Distributions

The previous section described how the local collection efficiency was calcu-

lated for a single droplet diameter. In icing applications, the mass median

droplet diameter of the droplet size distribution is used to characterize the

size of the droplets. A feature of the particle trajectory portion of the tra-

jectory program is that it allows the user to analyze the local collection

efficiency for a multidispersed particle distribution.

To perform this calculation, the user must input the droplet diameter

and the associated mass fraction and Cunningham correction factor for

each specified droplet size. A maximum of 10 droplet sizes can be used to

characterize a droplet distribution. For example, the required input for a

Langmuir D distribution with a mass median of 20.0 microns is shown in

Table 4.2.

The solution procedure is begun by calculating the local collection effi-

ciency distribution for each droplet size characterizing the distribution. The

19

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Table 4.2: Langmuir D droplet size distribution with a mass median of 20

microns

Percentage Ratio of Droplet Cunningham

LWC Diameters Diameter (/_m) Correction Factor0.05 0.31 6.2 1.0272

0.10 0.52 10.4 1.00

0.20 0.71 14.2 1.00

0.30 1.00 20.0 1.00

0.20 1.37 27.4 1.00

0.I0 1.74 34.8 1.00

0.05 2.22 44.4 1.00

local collection efficiency for the distribution is determined by summing the

contributions of each of the droplet sizes using the following equation:

N

(s) -- _ n, 8/(s) (16)i----1

where n/ is the mass fraction of liquid water associated with droplet di-

ameter i and N is the number of droplet sizes used to characterize the

distribution. The local collection efficiency for a droplet size distribution is

also calculated in subroutine EFFICY.

4.2.6 Computational Procedure

The previous sections described various aspects of the calculation of the

particle impingement characteristics. The purpose of this section is to

describe how these calculations work together to yield the desired local

collection efficiency information.

After calculating the flow field about the body, the program enters the

particle trajectory main subroutine, TRAJ. First, the initial particle loca-

tion x0, Y0 and velocity Vz_, Vvp must be determined, either by the computer

program or from information input by the user. A particle should be re-

leased at a location upstream of the airfoil where the flowfield is essentially

2o

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the same as the free stream conditions. The program will select an ini-

tial upstream x-coordinate, x0, by searching for a position where the local

velocity VL and the freestream velocity Voo satisfy the following inequality:

1 v,. ,,ol-.. (17)

where e (VEPS in the computer program) is specified by the user. Equation

(17) is tested over a specified range, Yo[,,_,, < Yo < Yo[,,_,_, where yolmin

and y0[,,_,z, illustrated in Figure 4.7, are also input by the user.

With the initial upstream x-coordinate known, the next step is to locate

two trajectories, one that passes above the body and one that passes below

the body. The vertical distances from which these particles are released,

y0[_ and yo],_in, respectively, are specified by the user. The calculation of

these particle trajectories is controlled by subroutine RANGE. Using these

upper and lower trajectories as boundaries, the upper and lower impinge-

ment limits, yo_, and yo_, are determined in subroutine IMPLIM (Figure

4.7b). This subroutine uses a Newton iteration scheme to determine the

release points for particles with trajectories that impinge upon the body

tangent to the surface. For example, when searching for the upper impinge-

ment limit, the trajectory of a particle released from Y011 = (v01_,_+vol-..) is2

computed. If the particle passes under or hits the body, the next trajectory

is computed from Y0]2 = (v0h+uol..s} If it passes over the body, the next2

trajectory is calculated from Y012 = (voh+vol.;.} Successive halving of the2

range Y01,,_, to Y0[,_z continues until the upper impingement limit is found.

Convergence of this iterative procedure is assumed when the difference be-

tween the Yo values of two trajectories, i.e., one that hit the body and one

that missed, is less than a small value specified by the user (YOLIM). This

procedure is then repeated for the lower surface to determine the lower

surface impingement limit. Any particle released between the upper and

lower impingement limits will strike the body and any particle released

from outside this range will miss the body.

With the limiting release points known, the program enters subroutine

COLLEC where the range of vertical position, y0_ to y0t, is divided into a

number (NPL) of equally-spaced increments prescribed by the user. The

trajectory of particles leaving each of these vertical positions is calculated,

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and the impingement position of the particle on the body surface is deter-

mined using the method previously described. The Y0 vs. surface distance,

s, information obtained in this calculation is then differentiated in subrou-

tine EFFICY to determine the local collection efficiency at the midpoint of

each of the body segments.

4.3 Calculation of the Thermodynamic Characteristics

The thermodynamic analysis of an icing surface was first developed by

Tribus 7 from the physical model of the ice accretion process previously

discussed. This model was used to calculate the heating requirements for

icing protection and proposed LWC measurement systems. Messinger s de-

veloped the thermodynamic model further to include an analysis of the

temperature of an unheated surface in icing conditions for three surface

temperature regimes, i.e., less than 273.15 K, equal to 273.15 K, and above

273.15 K, and the concept of the freezing fraction, f, to be discussed later.

These early formulations have been used in various icing applications.

As discussed in Section 3.2, microscopic movies of the ice accretion pro-

cess made at NASA Lewis Research Center 9 indicate that the process may

be more accurately modeled by modifying the equations used in past icing

studies. The observations reveal that, after the initial flow of the coa-

lesced droplets on the surface, the liquid does not flow but is caught and

frozen in the grooves between the individual surface roughness elements.

Incorporating this observation into a mathematical model would proba-

bly require modeling the individual roughness elements and the freezing of

pools of water surrounded on all sides by ice. A microscopic and possibly

three-dimensional analysis of the icing surface would be required to math-

ematically apply this model to an ice accretion prediction method. The

mathematical model used in this and previous studies is more macroscopic

in nature because the roughness elements do not directly effect the freezing

process except to enhance the convective heat transfer coefficient.

The equations that model the thermodynamics of the freezing process

on a body undergoing icing are formulated by performing a First Law of

Thermodynamic mass and energy balance on a control volume located on

the surface. The control volume to be analyzed is located on the surface of

the body and extends from outside the boundary layer to the surface of the

22

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body, asshownin Figure 4.8a. The lower boundary of the control volume is

initially on the surface of the clean geometry and moves outward with the

surface as the ice accretes. Therefore, the control volume is always situated

on either the clean or ice surface. Computationally, a control volume is

placed over each segment defining the body geometry, as shown in Figure

4.8b. The equations resulting from the mass and energy balance can be

expressed as follows:

Mass Balance:

rh,.o,., = (1.0 -/)(rh,, + m,...) - r'n,, (18)

Energy Balance:

?Jrh_[c_,.,,(T. - 273.15) + +

rhr,. [cz,u,.,ur(i-1)(T, ur(i+l } - 273.15)] + qkAs =

rh,[c_,,,,.,_,,.[(T,,,.- 273.15)+ L.]+

[(1 - f)(rhc + rh.,,.) - m,] e;,,,,.o,,,.(Tc,.,, - 273.15)+

frh,, - rh,.,. )[C_,o,,,.(T°_,,. - 273.15) - LI] +

ho[r..,-n2epa J A8

(19)

The complete derivation of Equations (18) and (10) is included in Appendix

A.

4.3.1 Definitions

Before discussing the method used to solve Equations (18) and (19), it is

necessary to discuss several of the terms that are important to the solution

procedure.

As discussed in Section 3.1, the atmospheric and meterological param-

eters determine the type of ice that will form for a given icing condition. It

has been found by various authors that the concept of a freezing fraction

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can be used to determine the type of ice that will form. The freezing frac-

tion, f, was defined by Messinger as the fraction of impinging liquid that

freezes within the region of impingement. In this application, f is defined

as the fraction of the total liquid entering the control volume that freezes

within the control volume. It is given by the equation

f - (20)

For colder icing conditions, the droplets tend to freeze immediately on

impact, resulting in the formation of rime ice. Since all the water entering

the control volume freezes within the control volume, the freezing fraction

equals 1.0. Freezing fractions close to 0.0 characterize glaze or clear ice.

Freezing fractions between approximately 0.3 and 1.0 will normally indicate

that the ice has some combination of glaze and rime characteristics. As

shown in Figure 3.1, ice accretions are often composed of glaze, rime, and

intermediate regions. The local value of the freezing fraction therefore

varies along the surface, and can be calculated using the mass and energy

balances given by Equations (18) and (19).

4.3.2 Solution of the Energy Equation

The evaluation of Equation (19) is begun at the stagnation point because

there will be no runback into the control volumes located on each side of

the stagnation point, as shown in Figure 4.8b. Therefore,

,_.,nl.ta,=,%nl.,o,_, =0.0 (21)

It is first assumed that the equilibrium surface temperature, Tour, equals

273.15 K. The terms of Equation (19) are then evaluated at this tempera-

ture, and the resulting expression is solved to determine the freezing frac-

tion, f. This calculation is performed in subroutine COMPF. The value

of f will be either 1) less than 0.0, 2} between 0.0 and 1.0, inclusive, or 3)

greater than 1.0.

For 0.0 < f < 1.0, T,u,. = 273.15K, and the initial assumption was

correct. A value of f < 0.0 indicates that the surface temperature is greater

than 273.15 K. Therefore, the solution is obtained by setting f = 0.0 and

solving for T,u, in subroutine COMPT. Note that an iterative procedure

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is required since many of the terms of Equation (19) are functions of To,r.

Similarly, f > 1.0 indicates that Tou, is less than 273.15K, and f should be

set equal to 1.0. Again, an iterative procedure must be applied to determine

TSUr "

When the thermodynamic characteristics of the control volume are

known, the mass balance given by Equation (18) is used to determine the

mass flow rate of runback water out of the control volume. Any water flow

out of the control volume will be away from the stagnation point and into

the next control volume.

The above procedure is then repeated for the adjacent downstream con-

trol volume and continued along the upper surface of the body. The entire

procedure is then repeated again, starting at the stagnation point and pro-

ceding along the lower surface of the body.

4.4 Calculation of the Iced Geometry

When the freezing fraction has been determined for each segment (con-

trol volume) on the body, Equation (20) is used to calculate the local ice

accumulation rate, rewritten below as

m, = f(_zc -1- m,.,.) (22)

This ice growth rate must be interpreted as an ice thickness to form an

ice accretion on the surface of the geometry. The thickness of the ice layer

grown on a particular segment is given by the equation

d_ = _' At + As (23)Pi

where Pi is the density of the ice, As is the length of the segment, and At

is a time increment specified by the user.

The density of the accreted ice is determined using the empirical expres-

sion developed by Macklin (Reference 18). This correlation was developed

from predominantly rime ice accretions at low temperatures and velocities

and is as follows:

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i

p,= (24)

In this expression, d,,_ is the mass median droplet diameter in microns, Va

is the droplet impact velocity in m/sec, and T0ur is the surface temperature

in °C. In the calculation, the freestream velocity Voo is used for Va. The ice

density has the units of kg/m s. Equation (24) is used to determine the ice

density when the atmospheric and meteorological parameters are such that

see °C - 2 T,_,, - see°C

and T0_, < -5°C. When these conditions are not satified, it is assumed

that the ice has a density of 917kg/m 3. In general, the inequality will be

satisfied under conditions of small droplets, low velocities, and low surface

temperatures. For example, with a droplet diameter of 12 microns and

a velocity of 60 m/s, the surface temperature must be less than -20 °C, a

rather extreme rime condition. The density of the ice accretion is evaluated

for each surface segment to allow mixed ice accretions to form (mixed ice

accretions contain both rime and glaze ice). The calculation of the ice

density is performed in function RHOICE.

The new ice surface is formed by first adding the ice thickness, d_, per-

pendicular to each segment, as shown in Figure 4.9. The adjacent endpoints

of each of these new segments are then averaged to obtain the coordinates

describing the new ice surface. The new ice surface is calculated in subrou-

tine NWFOIL using this procedure.

When the new surface is formed, the length of a segment increases.

The segments are allowed to grow but, at some point, must be split to

maintain adequate definition of the surface. The segment length is allowed

to increase until it is SEGTOL times the length of the original segment.

The value of SEGTOL is input by the user. When a segment has grown

to SEGTOL times the initial segment length, it is divided in half to form

two new segments, and a new point is added to the set of coordinates.

These two new segments will be allowed to grow to SEGTOL times their

current length before being divided. Note that a value of SEGTOL < 2.0

will result in progressively shorter segments. Values greater than 2.0 will

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result in progressively longer segments. The segment lengths are checked

and, if necessary, divided in subroutine NWPTS.

As the ice accretion grows, it is also possible for two lobes of the accre-

tion to grow together, causing some of the points to lie in the interior of

the body, as shown in Figure 4.10. These points must be removed in orderto continue the calculations.

The point removal procedure is begun by applying the same procedure

used to determine if two segments intersect, as shown in Figure 4. In this

case, each body segment is checked with every other segment, excluding the

two adjacent segments. As shown in Figure 10, if an intersection is found,

all segments between the two intersecting segments are removed, and the

set of coordinates is revised to reflect these changes. This procedure is

performed in subroutine SEGSEC.

4.5 General Computational Procedure

The previous sections discussed each of the individual phenomena of the

ice accretion process that are evaluated in LEWICE. The purpose of this

section is to describe how these individual calculations are implemented to

form a complete ice accretion.

As discussed in the Introduction, LEWICE applies a time-stepping pro-

cedure to grow an ice accretion. The flow field and droplet impingement

characteristics are initially determined for the clean geometry. The ice

growth rate on each segment defining the surface is determined by applying

the thermodynamic model. The new surface is then formed by specifying

an icing time and applying the procedure described in the previous section

to account for the accreted ice on the clean surface. After calculating this

initial ice layer, two options are available.

The most desirable option is to repeat the entire procedure, beginning

with the calculation of the flow field about the iced geometry, to obtain

revised local collection efficiency and thermodynamic data. Unfortunately,

since the majority of the computational time is spent calculating droplet

trajectories, this option also increases the computational time required to

accrete a layer of ice. Therefore, a second option was made available.

27

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If the amount of ice accreted during the time step is small or no new

protuberances, such as glaze horns, were formed, it is possible to accrete

another layer of ice using the same local collection efficiency curve calcu-

lated from the previous time step. This option, of course, does not produce

results that are as accurate as those in the first option, especially for glaze

ice accretions. The advantage is that the computational time required is

significantly reduced.

Each of these options will require that another time increment be spec-

ified. The above procedure is repeated by specifying discrete time incre-

ments until the desired icing time is reached. Guidelines for choosing an

appropriate time increment are also given in Section 5.3.1.

Ice accretions can have many geometrical shapes ranging from the

smooth, aerodynamically-shaped rime accretions to rough glaze accretions

with deep center grooves. LEWICE is therefore required to calculate suf-

ficiently accurate flow fields and particle trajectories about what can be

very irregular geometries where viscous effects such as boundary layer sep-

aration and reattachment are important. This can, at times, exceed the

capabilities of the potential flow code and produce non-physical results.

Much work has been done to identify and correct inaccuracies in the flow

field calculations. The techniques that have been implemented in the code

to overcome these flow field inadequacies will be discussed in many of the

following sections.

28

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Cp

-5.0

-4.0

-8.0

-2.0

-1.0

1.0

_.0 0

L!-I__ _-i--

I

LI

_I I I, I I !

.2 .4 .8 .8 1.0

x/ca. m=0.300; c.=-0.018;

I Ii

-_- Experimental

o Predicted

Ir_ I liL.

I

f _ i iI t tlI [I [ ]

0 .2 .4 .6 .8

x/c

b. m--0.300; c,,--0.577;

a=-O.14 a--5.88

1.0

\ " " i

E_[I IIi,:_

wl I

0

_! ii!iiFl!i

.2 .4 .B .8 1.0

x/c¢)m=0.299; e,_= 1.0,,6;

a=10.86

-.1.3 ......

-3.0

-2.0

l

Cp .l.0

.6 .8 1.0

x/c

d. m=0.499; cn=-0.014;

Experimental

o Predicted

i

\(:I-1

O,A- _

v, ,J u"0.o 3

LJ

0 .2 .4 .6 .8 1.0 0

x/c

e. m=0.500; cn=0.626; f.

a=-O.14 a=5.86 a=10.86

I

.2 .4 .6 .8 1.0

x/c

m=0.500; c,:0.966;

Figure 4.1 Comparison to experiment of pressure coefficient over a NACA

0012 airfoil calculated by the Douglas 2-dimensional flo@ code.

29

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•2.0

-1.$

-1.2

Cp -.4

.4

.8

1.2

go

J

.2 .4 .6 .8 1.0

x/c

m=0.698; e,=-O.O18;

_=-0.14

-_ Experimental

o Predicted

m_-E]

A L--

0

h.

.2 .4 .6 .8 1.0

x/c

m--0.697; cn--0.716;

a=5.86

L

2=r'-

i ....

___.---...

.2 .4

..............r]I

..... i ............. ,

_r_ :-_" ..........

_ ......

---I ....... __+ ..... ;--- --,

......... ] .....

.6 .8 1.0

x/c

m=0.801; e,,=O.021;

a=O.14

-0- Experimental

o Predicted-1.2

Cp o_- --I-h

,b.8_1!

1._ 0 ._ .4 .6 .8 1.0

x/a

m=0.798; c,,=0.367;jl

a=2,86

Figure 4.1: Continued.

3o

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tH

Js= = Upper - Surface Impingement Limit

st = Lower - Surface Impingement Limit

H = Forward Projection of the Airfoil Height

Total Collection Efficiency

YO

Em -H

E._ - H Ids

Local Collection Efficiency

Figure 4.2: Definition of total and local collection efficiency

Figure 4.3: Forces acting on an arbitrarily-shaped particle

31

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r SINGLE ELEJ_NT,/ CLOSED G£O_TRY/

//.-- PARTICLE /

1, N

i+I i

N

OT ----Z Oi,1

N = number of points describing the geometry (point 1 is the same as

poing N).

If xp, yp lies outside the body, Or = 0. If xp, yp lies on the body, Or = 7r. If

Xp, yp lies inside the body, Or = 2r

Figure 4.4: Illustration of the method to determine particle impact

r'-" PARTICLE POSITION

I AT PREVIOUS

I TIRESTEP F- CURRENT

I PARTICLE I-POINT OFI tI I POSITION _ INTERSECTIONI I

.....

I. Particle does not pass through

the segment being evaluated.

,........ ,.,.. _ --,- "" _ '" ''0 P1

II. Particle passes through the

segment being evaluated.

The particle passed through the segment being evaluated if all of the fol-

lowing criteria are satisfied:

IPI < PoPx

IN,+1 < N, N,+I

IPo < PoP_

INi < Ni Ni+l

Figure 4.5: Illustration of the method to determine the location of particle

impingement

32

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-.t_O

-.152

-.ISq

-.166

-.I§O

-,160

-.162

-.164

-.t6&

-.lk8

-.lTg

m

w

m

D

m

J|

POINTS FIT WITH A

gUADRAT IC POLYNORIAL ._,_

/ \\_/ \ \." \ o

//// _"

o

o

o

o

-._, .._, .._,, .._, ,.._, -._, -._, _o._,o o._,

S (M)

o.Ioz

Figure 4.6: Particle release position, Yo, vs. surface impace distances, s,

points used to determine the polynomial

33

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X - Xi, 1

X - Xi+ 2

q:

YO) MAX"_',,%,

q

- X i

*Y

+X

• ;I/1- 'U'---Y-_'_',,ol,,,,,,-<_

a. Criteria to determine the particle release location.

X z X 0 -_

Yt

v._ z-4, -_ -

l

SU = UPPER SURFACE II_INGEIIENT LIMIT

SL = LONER SURFACE II_INGEI, IENT LIIIII

\t- UPPER fANGENI S

,/' IRAJE£TORY y

/v, (I "

Y

,- C_OR[IR IC

'S / CIiORO LINE

b. Particle release locations for the upper and lower surface tangent trajectories

Figure 4.7: Definition of terms used to determine the Local Collection Efficiency.

34

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CONTROl VOLU_ --\

0

ROIINI)ARY LAYER --\\

\\

IIII

/APPROACH | NG /

WATER 0,_,/0

DROPLETS -_\ _/

0 _,,\ 0\\\\ / 0 \

\ / ",\ 0 \\

b// o/ o

o / o/

\o /o\ /

\_ o

o //_\o/

/

/- WAll R FIlM/

//

/

AIRFOI[

a. Single control volume on the icing surface.

+y'/ i

/ I/

ST T,. p0,., /r Z/

n_DvMc /," .......-.-:".4COIITROL VOUffiES -.-_-"

.4r, NODES

i I I _'_,

J

÷X

b. Thermodynamic control volumes over each segment defining the body geometry

Figure 4.8: Identification of the control volume used to formulate the ther-

modynamic equations

35

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ice s_#f "I'ilE. t+At

f#

l_.'"'f ""-,-,=_o_-i

/i,&

Figure 4.9:Illustration of the method to calculate the iced geometry

36

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®

® ®

® ®

a. Geometry with intersecting segments(_)and(_

(8)

/

/

b. Revised geometry with the intersecting segments removed. (The original

segment numbers from a. are in parenthesis)

Figure 4.10: Illustration of the method to remove points from the body

geometry

37

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Chapter 5

LEWICE INPUTS

This chapter presents the input format for a LEWICE input card deck.

Section 5.1 contains the documentation that is needed to set up, execute,

and make changes to the data deck. When more explanation is required,

the user should consult Section 5.2 which includes additional information

concerning input definitions and program options. Examples of the input

files are shown in Section 7.0. The interactive input requested by the pro-

gram is discussed in Section 5.3.

5.1 Input Format

The purpose of this section is to provide a quick reference to the input

parameters used in LEWICE. Additional information can be found in Sec-

tion 5.2 and in various sections throughout the text. Where applicable,

the sections that contain additional information about the parameters are

identified.

5.1.1 Potential Flow Input

CARD 01 Run Identification Card (8A4)

IDR

CARD 02 Potential Flow Code Control Parameters (NAMELIST $24Y)

Variable Description

ILIFT Lift Control Flag

= 0 This is not a lifting body

= 1 This is a lifting body

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IPARA

IFIRST

ISECND

IPVOR

INCLT

CLT

ICHORD

CCL

Element Geometry Flag

-- 0 Linear Elements

-- 1 Parabolic Elements

First-order Terms Flag

= 0 No first-order terms

= 1 First derivative term

= 2 Curvature term

= 3 Both first-order terms

Second-order terms flag

= 0 No second- order terms

= i Second derivative term

= 2 Curvature squared term

= 3 Both second- order terms

Vorticity Distribution Flag

= 0 Use constant vorticity between

body elements

= 1 Use variable vorticity

distribution

c_, a Flag

= 0 Angle of attack, a, is input

= 1 Total lift coefficient, cz, is input

Value of angle of attack (degrees)

or lift coefficient depending on the

value of INCLT

Reference Length Flag

- 0 The reference length used in

calculating c_ is to be set -- 1.0

= 1 The reference length used in

calculating c_ will be input as CCL

The value for the reference length

(chord) used in calculating ci

39

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IND

ISOL

IPRINT

IFILL

Individual Solution Flag

$24Y iscapable of calculatingthe

potential flow about up to 6 bodies

and then superimpose the resultsof

each. The possible values of IND are

as follows:

-- 0 Edge velocitiesare not calculated

for each body

- 1 Edge velocitiesare calculated

for each body

In LEWICE, only one body isinput and the

edge velocitiesare always required.

Therefore, IND - 1

Matrix Solution Method Control Flag

= 0 Use routine SOLVIT for the matrix

solution (used when a very large number

of geometry points have been input)

-- 1 Use routine QUASI for the matrix

solution

= 2 Use routine MIS1 for the matrix

solution. Maximum number of geometry

points is 101. Ifthe number of

points isgreater than 101, the program

willautomatically use SOLVIT.

Print/Punch Flag

= 0 Normal output

= 2 Print the individual matrices

= 7 Punch the output on cards

IPRINT should be set equal to 0 to

reduce the amount of printed output

Parabolic Integration Flag

$24Y calculatesthe forcesand moments

acting on the body using both trapezoidal

and parabolic integrationof the calculated

pressure coefficient.The resultsof the

trapezoidal calculationsare always output.

4O

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ICOMB

The value of IFILL determines whether the

parabolic results are printed.

= 0 Results of the parabolic integration are

not printed

= 1 Results of the parabolic integrations are

printed

Combination Solution Flag

= 0 No combination solution calculated

= 1 Combination solution calculated

CARD 03 x-Coordinates (6F12.7,2X,I1,1X,I1,1X,I1)

Column Variable Description

01-12 X(1)13-24 X(2)25-36 X(3)37-48 X(4)4_60 X(5)61-72 X(6)

75 INO

77 ISTAT

79 ITYPE

x-coordinate of the geometry. Up to

six coordinates may be input on each

card depending on how the INO flag is

set.

Number of data points per card. If

there are 6 values per card, INO may

be left blank.

Last Card Flag

=0 This is not the last

x-coordinate card. More cards

will follow.

=1 This is the last x-coordinate card.

x-Coordinate Flag

--3

41

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CARD 04 y-Coordinates (6FI2.7,2X,I1,1X,I1,1X,I1)

Column Variable Description

01-12 YO)13-24 Y(2)25-36 Y(3)37-48 Y(4)49-60 Y(5)61-72 Y(6)

y-coordinate of the geometry. Up

to six points may be input on each

card depending upon how the INO flag

isset.

75 INO

77 ISTAT

79 ITYPE

Number of data points per card. If

there are six values per card, INO

may be left blank.

Last Card Flag

= 0 This is not the last y-coordinate

card. More cards will follow.

= 1 This is the last y-coordinate

card.

y-Coordinate Flag

-4

5.1.2 Trajectory Code Input

CARD 05 Tajectory Input I (NAMELIST TRAJ1)

Variable Description

GEPS

VEPS

Convergence criterion for the integration

method of Gear

Accuracy criterion for the case when

LXOR = I (Section 4.2.6)

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DSHIFT

LCMB

LCMP

LEQM

LSYM

LYOR

LXOR

x-distance to shift coordinates after

the potential flow calculation to avoiddiscretization errors

Combination Correction Flag

= 0 Calculates the combination solution

using the method of $24Y

= 1 Calculates the combination solution

using the method of COMBIN-2D

Compressiblity Correction Flag

- 0 No correction for compressibility

- 1 Correct velocity values to account

for compressibility

Particle Initial Condition Flag

= 0 The initial x- and y-components of

the particle velocity will be input

: 1 The initial particle velocity is

equal to the flow at the initial

particle location (in equilibrium

with the flow)

Symmetric Flow Field Flag

- 0 Unsymmetric flow field (general case)

: 1 Symmetric flow field (only half plane

is computed)

y-Coordinate Particle Release Flag

= 0 Particle is released from the position

specified by YORC

- 1 Program determines the vertical particle

release position using YOMAX and YOMIN as

the initial guesses

x-Coordinate Particle Release Flag

- 0 Particle is released from the position

specified by XORC

: 1 Particle release position is determined

the criteria i[1- vo I,< VEPSusing

43

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NEQ

NPL

NSEAR

NSI

TIMSTP

Number of equations to be solved to

determine the particle trajectories

-- 4 Spherical, non-lifting particle

= 6 Lifting, rotating particle

Number of particle trajectories to be

computed to define the Y0 vs. s curve.

If NPL is set equal to 1, a single

trajectory isto be calculated.

Maximum number of trajectoriesallowed

to be calculated in the search for the

upper and lower impingement limits

Number of droplet sizesused to

characterize the cloud droplet

distribution (maximum of 10)

Initialvalue of the time step used in

the integrationof the particle

trajectoryequation (Gear's integration

method)

CARD 06 Trajectory Input II (NAMELIST TRAJ2)

Variable Description

CHORD

G

PIT

PRATK

XORC

YORC

Airfoilchord (m)

Acceleration of gravity (m/s 2)

Initialangle of the particleflight

reference line (Figure 4.3) (degrees)

Initialvalue of the particle angle

of attack (Figure 4.3) (degrees)

x-coordinate position of particle

release(Xo/chord). XORC need not

be input ifLXOR = 1.

y-coordinate position of particle

release (y0/chord). YORC need not be

input ifLYOR -- 1.

44

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XSTOP

YOLIM

YOMAX

YOMIN

VXPIN,

VYPIN

Maximum downstream distance, normalized

by the chord of the airfoil, for which

particle trajectories are calculated

Accuracy criterion for computing the

surface impingement limits

(Section 4.2.6)

Initial guess for the y-coordinate of

the upper surface tangent trajectory

release point (y0/chord)

(Section 4.2.6)

Initial guess for the y-coordinate of

the lower surface tangent trajectory

release point (y0/chord)

(Section 4.2.6)

x- and y-components of the particle

release velocity. They are input only

when LEQM = 0.

CARD O7 Droplet Distribution Characterization Card

(NAMELIST DIST)

Variable Description

DPD

FLWC

CFP

Droplet sizes in the distribution

(maximum of 10) (microns)

Fraction of LWC for each droplet size

specified in the distribution

Cunningham correction factor

(Section 4.2.2, Table 4.2)

5.1.3 Ice Accretion Input

CARD 08 Ice Accretion Data (NAMELIST ICE)

45

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Variable Description

VINF

TAMB

PAMB

LWC

DPMM

RH

XKINIT

SEGTOL

Free-stream velocity (m/s)

Static temperature (K)

Static pressure (Pa)

Liquid water content (g/m a)

Mass median droplet diameter of the

specified droplet distribution (microns)

Percent relative humidity

Initial value of the equivalent sand-

grain roughness of the icing surface

(Chapter 4.3, Appendix F)

Maximum amount any segment may grow

before it is divided in two

(Chapter 4.4)

5.2 User's Guide to Input Format

5.2.1 Potential Flow Input

As discussed in Section 4.1, the flow field used in LEWICE is calculated

using the Douglas potential flow method ($24Y). This code was developed

to calculate the flow field about a wide variety of geometries. Using this

code in an ice accretion prediction method decreases the generality required

by the potential flow code, and many of the input parameters and program

options are not necessary for this application. The input to the potential

flow code required by LEWICE users was simplified to include only the

applicable parameters. However, the potential flow computer code was

not modified and remains in its original form in LEWICE. Therefore, the

original input format to the potential flow code is still used and all input

parameters are required. The input parameters not found in NAMELIST

$24Y are set to default values in subroutine SETUP. In this subroutine,

the input file to the potential flow code is set up and written to unit 45. A

description of the complete input to the potential flow code written to unit

45 is given in Appendix C. Further details concerning the input parameters

can be found in Reference C-1 and C-2.

46

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5.2.2 Trajectory Code Input

This section provides the userwith additional information about many of

the input parameters to the particle trajectory code. Suggested values of

the parameters are also given.

5.2.2.1 Trajectory Input 1 (NAMELIST TRAJ1)

GEPS

This variable is the error test constant used in the integration method

of Gear. Single step error estimates made in the integration algorithm must

be less than GEPS in the Euclidean norm. The step size and/or order is

adjusted so that this criteria is met. See References 16 and 17 for additional

information on the parameter and the integration scheme in general.

Parametric studies were made to evaluate the effect of changing the

value of GEPS from 0.001 to 0.00001. Increasing the value of GEPS was

found to reduce the cpu time required to calculate each trajectory by allow-

ing larger integration step sizes to be used. Figure 5.1 shows how increasing

GEPS decreases the computational time per trajectory.

Unfortunately, larger values of GEPS also allow larger computational

errors which are reflected in the calculated particle impingement locations.

Computationally, GEPS should approach 0.0, but the required compu-

tational time would be excessive, as shown in Figure 5.1. A value of

GEPS=0.00005 was therefore used for all calculations.

VEPS

This parameter is used when the program is to locate the proper x

location at which to release the particles. The particles will be released

from an x location where, between YOMIN and YOMAX,

I1 I<_ VEPS

Increasing the value of VEPS will allow particles to be released closer to

the body and thereby decrease the number of integration timesteps required

for the particle to strike the body. The computational time will therefore

be decreased.

47

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No studies have beenmade to show the effect of releasingthe particlescloser to the body. The particles must be released in essentially free stream

conditions for physically accurate trajectories to be calculated. For this

reason, a VEPS value of 1.0 x 10 -s has been used for all calculations.

DSHIFT

The potential flow computer program has a relatively large discretiza-

tion error very close to the body. Figure 5.2, taken from Reference 12,

shows the longitudinal and vertical velocities around the leading edge of a

Joukowski airfoil. The velocity is computed for different constant values

of separation distance (DSHIFT) from the body, as illustrated in the in-

sert. Note the large oscillations in the flow field velocity near the surface.

These oscillations can cause erratic particle trajectories close to the body,

especially for small particles that are effected by small flow field perturba-

tions, and can cause fatal program errors to occur, thereby terminating the

program.

To overcome the effect of the discretization error near the body, an ar-

tificial impingement surface is generated by the computer program. This

surface is defined by displacing each point of the body by a small incre-

ment DSHIFT in the upstream z direction. This displacement essentially

increases the size of the body to include the region where discretization

errors are present. DSHIFT values of approximately .2 to .6 percent of the

chord length are commonly used. If irregularties in the impingement curves

or droplet trajectory calculations persist for a specific case, the DSHIFT

value should be increased. Additional information concerning this flowfield

correction can be found in Appendix C.

The artificial impingement surface is generated in the computer program

after the potential flow calculation. Thus, the flow field is not influenced

by the creation of the pseudo-surface. Also, this surface is discarded after

the collection efficiency has been calculated, and is not used when a new

ice surface is formed.

LEQM

This parameter is the flag to specify the initial velocity of the particle.

In cases where an ice accretion is to be formed, the particles should be

released in equilibrium with the flow, i.e., LEQM = 1. The option exists

to specify the x- and y- components of the initial particle velocity when

48

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LEQM = 0. This option could be used along with the options to specify

the particle release position to simulate a droplet being ejected from a spray

nozzle.

LSYM

If a body and flow field are symmetrical, the local collection efficiency

distribution will also be symmetrical. Therefore, particle trajectory and

impingement locations need to be calculated only for either the upper or

lower surface. The local collection efficiency distribution is then assumed

to be identical for the opposite surface. When LSYM = 1, the droplet im-

pingement characteristics will be calculated only on the upper surface, and

the local collection efficiency distribution is specified to be identical on the

lower surface. When LSYM = 0, the droplet impingement characteristics

are calculated for both the upper and lower surfaces.

While some clean geometries are exactly symmetrical, the ice shapes

rarely have exactly symmetrical surface coordinates. Forcing symmetrical

collection efficiency distributions onto these surfaces has caused inaccurate

ice shapes to form. Therefore, it is suggested that, unless three or fewer

time-steps are to be performed, LSYM be set equal to 0 even for symmet-

rical bodies at zero angle of attack. Of course, the computational time will

be longer, but, in general, fewer problems will be encountered.

LYOR, LXOR

These are the x- and y-coordinate particle release flags used to indicate

whether the particle release position will be specified by the user or de-

termined in the computer program using the criteria discussed in Section

4.2.6. When using the code to predict ice accretions, it is better to let the

code determine the particle release positions. The positions that might be

specified by the user for the clean geometry may be unsatisfactory as an

ice accretion grows. These options have been included so that the code can

also be used to calculate individual trajectories of particles released from a

specific person.

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NPL

This parameter is used to specify the number of particle trajectories

calculated in subroutine COLLEC to define the Yo vs. s curve. The curve

will be better defined when more trajectories and impingement locations

are calculated. This, of course, is done at the expense of computational

time. While a maximum of 50 trajectories can be calculated, NPL = 15 is

normally specified.

If NPL is set equal to 1, the impingement limits will not be calculated

and the program will calculate the trajectory of only one particle. The

particle will be released from a position specified by XORC, YORC.

NSEAR

The criteria to identify an impingement limit are specified by the pa-

rameter YOLIM. If this specified parameter is specified too small, an exces-

sive number of trajectories could be calculated. This parameter limits the

number of trajectories that can be calculated while searching for the im-

pingement limits; a value of NSEAR = 50 is normally input. Calculations

of excessive numbers of trajectories can also be caused by erroneous input

values and coordinates defining the body geometry.

TIMSTP

As mentioned in the description of the GEPS parameter, the integra-

tion step size is determined in the program so that the single step error

estimate is less than GEPS. Since the program automatically determines

the step size during the integration, the value of the initial step size is not

critical. A value of TIMSTP = 0.0005 has been used consistently for all

calculations. This value is then decreased or increased as required in the

computer program.

NSI

This parameter specifies the number of droplet size increments used to

characterize the cloud droplet size distribution. If a monodispersed cloud

is to be input, NSI = 1. The effect of using a multidispersed droplet

distribution as opposed to a monodispersed distribution to determine an

ice accretion shape is discussed in Section 7.4.

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5.2.2.2 Trajectory Input II (NAMELIST TRAJ2)

CHORD

The chord of the airfoil(or diameter for a cylindricalbody) is used

as the reference length for the coordinate release inputs discussed in this

section. The chord isinput in meters.

G

The acceleration of gravity is input in m/s 2. If it is input as zero,

the effectof gravity on the particle trajectoriesis neglected. The effect

of gravity on the trajectoriesof droplets lessthan 50.0 microns isusually

negligible,and is therefore omitted in most icing studies19. The effectof

gravity was omitted for allof the sample cases in thisreport except for the

ones using a multidispersed droplet distributioncontaining droplets larger

than 50.0 microns.

PIT, PRATK

PIT is the initial particle pitch angle, which is defined as the angle be-

tween the axis oriented parallel to the airfoil x- axis and the flight reference

line (See Figure 4.3 and Section 4.2.2). For spherical, non-rotating particles

(such as water droplets) PIT = 0.0. PRATK is the initial particle angle of

attack and should also be set equal to 0.0 for spherical particles.

When LEWICE is used to calculate ice accretion shapes, PIT and

PRATK should both equal 0.0. The option to calculate the trajectories

for non-spherical, rotating particles has been included so that the particle

trajectory calculation may be useful for alternate applications, however,

appropriate equations for the lift, drag, and moment coefficients must be

supplied by the user and placed in subroutine COEFF. The subroutine was

developed so that the coefficients are functions of the Reynolds number and

the particle angle of attack.

XORC, YORC

These parameters are used to specify the particle release location when

LXOR = 0 and LYOR = 0. XORC and YORC should be input normalized

with respect to the airfoil chord length.

XSTOP

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This parameter isthe maximum downstream value of x/chord for which

particle trajectoriesare calculated. If a particlereaches a location where

x > XSTOP, it isconsidered to have missed the body and moved out of

range. This rear boundary of the computational box should extend at least

past the location of maximum thickness, and often further, depending on

the geometry and angle of attack. Ifthe value of XSTOP isgreater than the

maximum x-coordinate defining the body (XREAR), XSTOP isset equal

to XREAR.

YOMAX, YOMIN

These are the initial guesses for the y-coordinate of the upper and lower

surface tangent trajectory release points, normalized with respect to the

chord.

YOLIM

YOLIM is the accuracy criteria to be used in determining when an im-

pingement limit has been reached. As discussed in Section 4.2.6, when the

release points of two trajectories (one that hit the body and one that missed

the body) are within YOLIM, the trajectory that hit the body is identified

as either the upper or lower surface tangent trajectory. The smaller the

value of YOLIM, the greater the number of trajectories that will have to be

calculated to identify the tangent trajectory. A practical value for YOLIM

is 0.0001; this value is used for all sample calculations.

VXPIN, VYPIN

These values are the x- and y-components of the initialparticlevelocity

in m/s. These values need to be input only when LEQM = 0.

5.2.2.3 Droplet Distribution Input (NAMELIST DIST)

DPD

This array is used to specify the droplet sizes characterizing the distri-

bution. The droplet sizes should be input in microns.

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FLWC

FLWC is the fraction of the total liquid water content contained in eachdroplet size increment.

CFP

This parameter is the Cunningham correction factor (Reference 15).Small particles, i.e., those lessthan 10.0microns, have a drag slightly lessthan that given by the equation for spheres in cross-flow. The Cunning-

ham correction factor is used to correct the drag coefficient given by the

equations in subroutine COEFF. The correction factors are found in Table

4.2.

5.2.3 Ice Accretion Input (NAMELIST ICE)

VINF, TAMB, PAMB, LWC, DPMM, RH

These variables are used to specify the icing condition. The pressure and

temperature inputs are static conditions. The variable DPMM is the mass

median droplet diameter of the specified droplet distribution in microns.

If a monodispersed cloud is specified (NSI = 1), DPMM is equal to the

droplet size specified as DPD. When a multidispersed cloud is specified

(NSI = 1), DPMM should still be input because it is used as a label on the

parameter plots.

XKINIT

This parameter is the initial value of the equivalent sand-grain rough-

ness of the icing surface. The integral boundary layer method applied to

calculate the convective heat transfer coefficient uses this variable to ac-

count for the effect of surface roughness. The value of XKINIT is input

by the user and obtained using a relationship that expresses XKINIT as a

function of static temperature, velocity, and LWC. The value of XKINIT

is constant throughout the icing encounter. A discussion of the procedure

used to determine this relationship is given in Appendix F.

SEGTOL

To maintain adequate definition of the body geometry, it is necessary

to divide segments as they grow. This variable is the maximum fractional

amount by which a segment may increase in length before being divided in

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two. A value of SEGTOL < 2.0 will result in progressively shorter segments.

Values greater than 2.0 will allow the segments to grow progressively longer.

A value of SEGTOL = 1.5 has been found to work well in most icing

predictions.

QCOND

This variable is used to input heat flow either to or from the body

surface. The values of QCOND are input in W/m 2 as a function of surface

distance. It can be used to simulate thermal anti-icing systems, but is not

applicable to de-icing systems since the thermodynamics of the ice-to-liquid

phase change at the surface of the body are not modeled. The results can

only be assumed to be correct for the first timestep because, the effect

of conduction through an ice layer formed during the first timestep is not

modeled.

5.3 Interactive Input

The timestepping feature of LEWICE ca;n, at times, cause conditions to

exist that require the user's interaction. This section describes the pri-

mary interactive prompts and responses required in the computer code.

Several interactive prompts are also made to indicate an unusual condition

requiring analysis by the user. These will be discussed as they occur in the

examples in Section 7.0.

After the primary input file (unit 35) has been read and the potential

flow and particle trajectory files have been set up, the program will prompt

the user to enter the desired icing time (in seconds). The icing time is

considered to be the total length of time that the accretion is to be grown.

The prompt will read as follows:

TIME = 0

ENTER DESIRED ICING TIME (SEC), (F10.0)

Upon entering the icing time, the program will then prompt the user to

enter the desired time increment for the first timestep with the following

statement:

ENTER DESIRED TIME INCREMENT (SEC), (F10.0)

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A general guideline for selecting an icing time increment for a given icing

condition is discussed in Section 5.3.1.

The user will then be asked to select the desired plot options. The

prompt will be as follows:

AVAILABLE PLOT OPTIONS

0- NO PLOTS

1- PARAMETER PLOTS ONLY

2- TRAJECTORY PLOTS ONLY

3- PARAMETER AND TRAJECTORY PLOTS

ENTER PLOT OPTION ()

If plot option 2 or 3 is chosen, the trajectories will be plotted immediately

after each is calculated. The trajectory points axe not saved and, therefore,

are lost when subsequent trajectories axe calculated. Plot options 1 and 3

will send the program into a plotting routine after the completion of the

timestep so that the significant parameters can be plotted. The plotting

routine uses a menu from which the following plots can be selected:

01 - Iced airfoil

02 - Particle release point (Y0) vs. Surface impact distance(s)

03- Local collection efficieny (/_) vs. Surface distance(s)

04- Edge velocity (Ve) vs. Surface distance(s)

05- Edge temperature (W,) vs. Surface distance(s)

06- Edge pressure (P,) vs. Surface distance(s)

07- Surface temperature (T,u,) vs. Surface distance(s)

08 - Convective heat transfer coefficient (h,) vs. Surface distance(s)

0g - Equivalent sand-grain roughness height (k,) vs. Surface distance(s)

10 - Ice density (p,) vs. surface distance(s)

11 - Freezing fraction (f) vs. surface distance(s)

Examples of these plots axe given in Section 6.0, LEWICE Output.

5.3.1 Selection of an Icing Time Increment

The timestepping procedure makes LEWICE unique among ice accretion

prediction methods because it allows the physics of the ice accretion to

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be more accurately modeled. Unfortunately, the procedure also adds com-

plexity to the model because a proper time increment must be selected by

the user. Also, the timestep will influence the ice accretion shape for a

specific icing condition; the shape is not uniquely determined by the icing

conditions. For example, Figure 5.3 shows three glaze ice accretion shapes

calculated for the same icing condition, but with different timesteps. In

Figure 5.3a, the accretion was formed in a single timestep. This shape

has the basic shape of the experimental ice accretion but lacks much of

the detail. Figures 5.3b and c show the same accretion formed at shorter

timesteps. Note that, as the timestep is decreased, the predicted accretion

takes on more of the characteristics of the experimental ice shape. Similar

results for a rime ice accretion are shown in Figure 5.4. These results indi-

cate that there is some maximum amount of ice that should be deposited

during a single timestep. On the other hand, when a short timestep is se-

lected, more steps are required to form the final ice shape, which increases

the computational time required for each icing condition.

Many ice accretion shapes have been calculated during the development

of LEWICE, and a criterion has been developed to help the user select an

appropriate timestep. Various authors have developed a term known as the

accumulation parameter, which is given by the following equation:

A° = _1,,,,,, V_ LWC ,',t (25)cpi

where c is the chord length of the body geometry (Some authors omit the

factor fll,,_z in the definition of A,_9.} The accumulation parameter is rep-resentative of the non-dimensional maximum thickness of the ice accreted

during time At. Therefore, a limiting value of A, could be used to de-

termine the length of a timestep. However, it was found that when ice

shapes were formed on an airfoil at an angle of attack, better results were

obtained using timesteps shorter than those used when the airfoil was at

0.0. Equation (25) was modified as follows:

_, = _l,,,_t V¢_ (LWC) At (1 + _) (26)c Pi

where a is in degrees. When comparisons with experimental ice accretions,

the modified accumulation parameter was generally less than. 1. Therefore,

the following equation can be used to calculate the time step:

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at < (.i) (9.17× i05_) c (27)- _i._z vooLwC (I + _)

Suppose that an ice accretion is to he formed on an airfoil with a chord

of 0.3 m at the following icing condition:

Velocity = 80.0 m/s

LWC = 1.2 g/m s

Angle of attack = 4.0

Icing time = 5.0 min

If the value of _[._.z, the maximum value of the local collection efficiency,

is known, it should be used to evaluate Equation (27). If not, a value of

0.80 is a reasonable upper limit and can be substituted into Equation (27).

The equation is evaluated as follows:

At < (.1) (9.17 × lOSg/rn s) (.3m)

- o.8o(8o,_I_)(1.2glrns) (1+ _0)

< 29.85seconds ,,, 30.0seconds

This indicates that the initial timesteps should be no greater than 30.0

seconds. Since Equation (27) was developed only to provide guidance in

selecting a timestep, it is always appropriate to round the calculated time

to a whole number.

Depending on the icing condition and size of the geometry, a time in-

crement may be calculated that is greater than the total icing time. In this

case, it is recommended that the total icing time be divided into at least

two, and perhaps three, timesteps even though Equation (27) indicated the

ice could be accreted in one step. If a single step were used, none of the

time dependent features of the accretion would be calculated by LEWICE.

It was found that more realistic ice accretions are predicted if at least two

timesteps are used.

There is one additional note concerning the selection of a timestep.

Depending on the icing condition, the predicted shape can become very

convoluted and irregular after several time.steps and computational inac-

curacies, such as multiple calculated stagnation points, may occur. If the

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multiple effects of these approximations cause the abnormal termination

of the code or the formation of a non-physical ice accretion, increase the

timestep and re-run the condition. By doing so, the user can get an idea

of the general size and shape of the accretion. By comparing this result

to the accretion obtained using the shorter timesteps, the accuracy of the

prediction can be evaluated.

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150

11o

Figure 5.1:

9Oo 5 10

GEPS

• I I I15 20 25x10 -q

Computational time as a function of GEPS

8

_J

1.20

.8_

• q% --

,08 --

-. JO- .08

I I I I I-.05 -.03 0 .03 .05

SURFACEDISTANCE, slJ_c

.O8

Figure 5.2: Discretization error in the flow field near the nose of a Joukowskiairfoil.

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EXPERIMENTAL (REF. 20) (a) At = 120.0 SEC.

(b) 4,t = 60.0 SEC. (c) &t = 40.0 SEC.

VELOCITY (M/S) 129.00

TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75

Hm,aDITY oo.ooLWC (G/M s) 1.00

DROP DIAM (MICRONS) 20.00

TIME (SEC) 120.00

Figure 5.3: Effect of icing time increment on a calcualted glaze ice accretion.

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At = 120 SEC

At = 60 SEC

At = qO SEC

TOTAL ICING TIME = 120 SEC

VELOCITY (H/S) 60.00

TEHPERATUR[ (C) -26.I5

PRESSURE (KPA) 98.80

HUHIOITY (X) 100.00

LWC (G/H--3) 1.00

OROP OIAM (HICRONS) EO.O0

TIHE ($ZC) 120.00

Figure 5.4: Effect of icing time increment on a calculated rime ice accretion

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Chapter 6

LEWICE Output

The standard output from LEWICE consists of both printed and plot-

ted output. The printed output is made available primarily for diagnostic

purposes and examination of the calculated values. Most comparisons of

calculated variables and ice shapes are made with the graphics routines

provided in the code. The output discussed in this section is the output for

the sample case presented in Section 7.1.

6.1 Printed Output

Printed output is produced by the potential flow, particle trajectory, and

ice accretion portions of the computer code. All output is printed on unit

56. The following sections describe the printed output from each of these

portions.

6.1.1 Printed Output from the Potential Flow Code ($24Y)

All write statements contained in the original version of $24Y are included

in LEWICE, however, many of these write statments have been commented

out to reduce the amount of printed output.

The initial output from the potential flow code is a listing of the input

geometry coordinates, as shown in Figure 6.1a. Following the coordinate

listing are the calculated non-dimensional surface velocities and the body

pressure coefficients, as shown in Figure 6.lb. A description of each of the

parameters printed on this output page is as follows:

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ALPHA

ALPHA O

CL

CHORD

NO. OF ELEMENTS,

TOTAL ELEMENTS

I, J

X, Y

S

VT

Angle of attack (degress) specified by the user

Calculated angle of zero lift (degrees)

Calculated lift coefficient. The reference length

is that specified by CHORD

Chord length (meters) specified by the user to

use as the reference length in the calculation

of CL

Number of segments specified to define

the body geometry

Segment number

x,y coordinates of the midpoint of each

segment

Surface distance to the midpoint of each

segment

s = 0.0 corresponds to the trailing edge of the

body (point number 1)

Non-dimensional surface velocity given by the

following equation:

CP

VT=--

Surface pressure coefficient, cp calculated

from VT using the following equation:

CP = 1.0 - VT 2

The force coefficients (lift, moment, normal, axial, and pressure drag)

are calculated from the pressure coefficient data and printed after the data

described above. These variables are calculated using two methods from

the same set of pressure coefficient data. The first method integrates the

pressure coefficient curve using the trapezoidal rule while the second uses

Simpson's rule.

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6.1.2 Printed Output from the Particle Trajectory Code

The first output from the particle trajectory code will be a statement iden-

tifying the x location from which the particles were released, X0. This

output, shown in Figure 6.2, is a result of the calculations performed insubroutine RELEAS.

The next output consists of the identification of some of the geometry

characteristics. All of the values are dimensional with standard units in the

MKS system. Recall that the geometry coordinates have been adjusted to

avoid the discretization errors in the flow field calculation (Appendix C).

The values of the leading edge, trailing edge, and thickness are determined

from these modified values and not from the original input coordinates.

This computational correction is removed before the collection efficiency

calculation and the calculation of the new ice surface.

The particle trajectory data begin after the geometry characteristics are

printed. The first output is a statement identifying how the particles were

released. If the particles are released in equilibrium with the air (LEQM =

1), the following message will be printed:

The particles are released in equilibrium with the air.

If LEQbf = 0, no message is printed, and the particle release velocities

are specified by the user. In this case, the initial particle velocities are

printed in the line of data shown in Figure 6.2.

Note that when LEQM = 1, the initial particle velocities are shown to

be 0.0 m/s. This indicates that the user did not specify the input velocity.

The initial velocity of each particle is determined by the program and will

depend on the particle release location.

The next statement will indicate the percent mass of each particle cor-

responding to the droplet diameter specified. Following this statement, the

results of the integration of the particle trajectory equations are printed.

This output indicates whether a particle released from a point X0, Y0 im-

pinges on the body. The column headings used in this section of the output

are defined as follows:

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XO

YO

XP

YP

S

DT

B

I

NSTP =

x-location of particle release

y-location of particle release

x-location where particle either impinged

upon the body or moved out of range

y-location where the particle either impinged

upon the body or moved out of range

surface distance from the stagnation point

to the particle impingement point (lower surface

is negative)

size of the integration timestep when the particle

either hit the body or moved out of range

number of integration timesteps required for the

particle to either impinge upon the body or move out

of range

As discussed in Section 4.2.6, particle trajectories are first calculated

to determine the impingement limits in subroutine IMPLIM. The release

points for the upper and lower surface tangent trajectories are defined as

the particle release positions. A particle released between these points

will strike the body, and one released outside of these points will miss the

body. When the impingement limits are found, they will be printed as

shown in Figure 6.2. The remaining particle trajectory calculations, for

particles released between the upper and lower surface tangent trajectory

release points, are made in COLLEC. All of these particles should strike

the body, and are used to determine the local collection efficiency. When

a droplet distribution has been specified, the output shown in Figure 6.2

will be repeated for each droplet size before continuing with the collection

efficiency calculation.

After completing the calculation of the impingement limits for each

droplet size, the program enters subroutine EFFICY, where the local col-

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lectionefficiencyiscalculated. The output consistsof the calculated _/ovs.

s points that form the curve that isdifferentiatedto determine the local

collectionefficiency,as shown in Figure 6.3a. This isfollowed by the surface

distance and calculated local collectionefficiencyfor each body segment.

An example of thisoutput isshown in Figure 6.4b. Ifa droplet distribution

has been specified,the output shown in Figure 6.3a and b is printed for

each droplet size.

When a droplet distributionhas been specified,the localcollectioneffi-

cienciesfor each droplet sizein the distributionmust be combined to form

a cumulative local collectionefficiencydistribution. The local collection

efficiencyfor each body segment corresponding to a specificdroplet size

is weighted using the fraction of the total mass specifiedon input. This

weighting procedure isdescribed in Section 4.2.5.1.These cumulative val-

ues are used in the thermodynamic and ice accretion portions of the code.

6.1.3 Printed Output from the Ice Accretion Code

The first page of output from the thermodynamic and ice accretion por-

tions is shown in Figure 6.4a. This output contains the run identification

specified by the user on input, and the current icing time in seconds. The

free stream icing conditions are then printed, followed by general informa-

tion concerning the thermodynamic and ice accretion calculations. This

information contains the body segment numbers corresponding to the stag-

nation point, the upper and lower surface boundary layer transition points

(transition from laminar to turbulent flow), and the upper and lower sur-

face icing limits. The total number of points used in the calculation of

this timestep is given, followed by the number of segments added to the

geometry generated by the previous timestep.

Following this page are three pages containing the detailed output of the

most significant aerodynamic, thermodynamic, and ice accretion parame-

ters. All of these parameters are functions of the surface distance, s, and

are shown in Figure 6.4b. The column headings in the computer output

are defined as follows:

Page 1

I - Body segment number

X - x-coordinate of the iced surface corresponding

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y

S

VE

TE

PE

RA

SEGLENGTH -

to segment I (m)y-coordinate of the iced surface corresponding

to segment I (m)

Surface distance, s, to the midpoint of segment I (m)

Velocity at the outer edge of the boundary

layer,Ve, (m/s)

Static temperature at the outer edge of the

boundary layer,Te, (K)

Static pressure at the outer edge of the

boundary layer, P., (Pa)

Density of the air at the outer edge of the

boundary layer,po, (kg/m s)

Length of the body segment, s, (m)

Page 2

HTC

XK

BETA

FFRAC

RI

TSURF

DICE

- Convective heat transfer coefficient, he,

(WIm'IK)

- Equivalent sand-grain roughness height,

k., (m)

- Local collectionefficiency,/_

- Freezing fraction,f

- Density of the ice, pi, (kg/m s)

- Equilibrium surface temperature, Tour, (K)

- Thickness of the ice accreted in the current

timestep, d_, (m)

Page 3

QCOND

MDOTC

MDOTRI

MDOTE

- Conductive heat flux from the body surface,

qo,(wire')- Mass flux of liquid impinging in segment I,

rhc (kg/s)

- Mass flux of liquid water running along the

surface into the control volume, the.,

of segment I

- Mass flux of water vapor evaporating from

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MDOTTI

MDOTT

the control volume, rh,,of

segment I (kg/s)

- Total mass fluxof water entering control

volume, rhT_, of segment I (kg/s)

- Total mass flux of water in to control volume

rhr, of segment I (kg/s)

This concludes the descriptionof the printed output from LEWICE. All

of the output described above isrepeated for each time step.

6.2 Graphical Output

While the printed output isusefulto verifywhether the code isperforming

as expected, much of the output from LEWICE isdisplayed graphically to

aid in the evaluation of the results.

The plotting commands used in LEWICE are unique to NASA Lewis

Research Center and, therefore,are not likelyto be directly applicable to

another facility.GRAPH2D/GRAPH3D commands are used.

All plots discussed in this section have the same border, which contains

title and icing condition information.

6.2.1 Droplet Trajectory Plots

As discussed in Section 5.3.1, when plot option 2 or 3 is selected, the particle

trajectories will be plotted. An example of five such plots are shown in

Figure 6.5. The axes limits (in meters) are determined by the program

so that the entire body geometry is plotted. When a particle impinges

upon the body, the y-coordinate of the release point, y0, and the surface

impingement distance, s, are displayed on the plot. If the particle misses

the body, this information is omitted.

The plotting commands are located in subroutine PLTRAJ, which is

called from subroutine INTIG after the calculation of the trajectory is com-

pleted. Each trajectory is plotted immediately after it is calculated and,

once the calculation of a new trajectory is begun, the previous trajectorycoordinates are erased.

68

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6.2.2 Ice Accretion Data

Much of the ice accretion data (Section 6.1.3) can also be plotted to as-

sist the user in interpreting the results. If plot option 1 or 2 has been

selected, the program will enter the plotting routine (subroutine PLOTD)

after completing the ice accretion calculations. The following plot menu

will be displayed upon entering the plot routine:

AVAILABLE PLOT OPTIONS

0 NO PLOTS

1 ICED GEOMETRY

2 ZVSS

3 - BETA VS S

4 - VE VS S

5 - TE VS S

6 - PE VS S

7 - TSURFVSS

8 - HTC VS S

9 - XK VS S

10 - ICE DENSITY VS S

11 - FFRAC VS S

ENTER OPTION NUMBER (I2)

The user then inputs the two-digit identifier for the desired plot.

When plot 01 is selected the iced geometry, with all preceding timesteps,

will be plotted. Before plotting the geometry, the user will be asked to

specify the percent of the geometry to be plotted with the following prompt:

ENTER PERCENT OF GEOMETRY TO BE PLOTTED (F10.0)

Since the size of the plot is fixed, the larger the portion of the airfoil to

be plotted, the smaller the geometry will appear on the plot. For example,

Figures 6.6a, b, and c show geometries plotted with the specified percent

equal to 100, 50., and 25., respectively. After the geometry is plotted, the

program will return to the plot menu.

Plots 02 to 11 are all parameters that are functions of the surface dis-

tance, s. The format for all of these plots is similar and is described below.

69

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After selectingthe desired plot, the minimum and maximum values on

the ordinate and abcissa willbe displayed. After each maximum and min-

imum isdisplayed, the user willbe asked to specify the desired axis limit.

After the desired limitsare input, the program willask ifexperimental data

isto be plotted, i.e.,

ENTER 1 IF EXPERIMENTAL DATA IS TO BE PLOTTED IF NOT,

ENTER O

Ifexperimental data are to be plotted, the program will firstask for the

number of data points, and then ask the user to manually input the data.

After the lastexperimental data point is input, the plot will be displayed,

and the experimental data willbe represented as circles.

After viewing the plot, the user willbe given the chance to change the

axes limitswith the following prompt:

IF YOU WOULD LIKE A DIFFERENT SCALE, ENTER 1. IF NOT,

ENTER O.

If this is desired, the maximum and minimum ordinate and abcissa values

will be displayed again, and the above procedure is repeated. If new axes

limits are not desired, the plot menu will be returned to the screen.

As previously stated, plots 02 to 11 all use the operating format de-

scribed above with the occasional exception of plot 02, yo vs. s. When a

droplet distribution is specified, the Y0 vs. s curve corresponding to each

droplet size will be plotted. The correct droplet size for each plot will be

printed in the parameter box in the upper left-hand corner of the plot. The

user will be asked to input the maximum and minimum axes limits for the

plot of each droplet size.

Examples of each of the parameter plots (02-11) are shown in Figures

6.7a-k.

70

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<,56709

I0II

13I<,1515

1819202122232<,2526272829303132333<,3536373839<,0<,I<,243<,4<,5<,6q748<,950

UNTRANSFORMED

I X(II1 1 0000000Z 0 98999993 0 9800000

0 97000000 9500000

0 92500000 90000000.87500000.85000000.82500000.80000000.77500000.75000000.72500000.70000000.67500003.65000000.62500000.6000000

0.57500000 5500000

0 52500000 5000000

0 47500000 45000000 4250000

0 40000000 37500000 33000000 52500000.30000000.27500000.25000000.22500000.20000000.17500000.15000000.12500000.10000000.09000000.08000000.07000000.06000000.05000000.04500000.04000000.03500000.03000000.02500000.0200000

COO_DItIATE DATA FOR BODY ID =

Y(I) I0.0000000 51

-0.0018740 52-0.0036110 55-0.0032390, 54-0.0082510 55-0.0117000 56-0.0149080 57-0.0179550 58-0.0208880 59-0.0237390 60-0,0265150 61-0.0292210 62-0.0318550 63-0.0344110 64

-0.0368870 65-0.0392810 66-0.0415850 67-0.0437950 68-0.0<,590<,0 69-0.0479060 70-0.0497930 71-0.0315600 72-0.0531980 75-0.0546980 74-0.0560510 75-0.0572430 76-0.0582620 77-0.0590900 78-0.0597070 79-0.06009q0 80-0.0602260 81-0.0600760 82-0.0596120 83-0.0587940 84

-0.0575700 85-0.0558790 86-0.0536360 87-0.0507320 88-0.0470040 89-0.0452280 90-0.0432520 91-0.0410380 92-0.0385350 93-0.0356740 9_-0.0340820 95-0.0323620 96-0.0304960 97-0.0284620 98-0.0262300 99-0.0237260 100

1, HACA 0012

X(I)0.0150000 -00.0100000 -00.0075000 -00.00500000.00375000.00250000.00225000.00200000.00175000.00150000.00125000.00100000.00087500.00075000.00062500.00050000.00037500.00025000.00012500.00000000.00012500,00025000.00037500.00050000.00062500.00075000.00087500.00100000.00125000.00150000.0O175000.00200000.00225000.00250000.00575000.00500000.00750000.01000000.01500000.02000000.02500000.03000000.03500000.0400000O.OqSO0000.05000000.06000000.07000000.08000000.0900000

: EXAMPLE 1

Y(I)020797001724800150780

-0 0123860-0 O1O699O-0 0086200-0 0081360-0 0076230-0.0070750-0.0064850-0.0058470-0 005146O-0 00_7660-0 0043630-0 0039310-0 0034620-0 0029450-0 0023560-0 0016320

0 00000000 00163200 00235600 00294500 00346200 00393100 00436300 00476600 00514600 0058_700 00648500.00707500.00762300.00813600 00862000 01069900 01238600 01507800 0172q800 02079700 02372600 02623000.028q6200.030_9600.03236200.03408200.03567400.03853500.04103800.04325200.0q52280

a. Geomentry coordinates input.

DOUGLA_

COHBINED FLCU

ALPHA : 0.000000

CL : -0.000001

BODY ID : 1

I ×I 0 99500302 0 98500223 0 9750018<, 0 96000<,55 0 93750q<,6 0 91250307 0.88750188 0.86250119 0.8375007

10 0.8125005II 0.7875000

12 0.762500813 0.7375007l<, 0.717500615 0.6875005

16 0.6_2500917 0.6375008

18 0.612500819 0.5875007_0 0.562500621 0.5375010_ 0.512500923 0.<,8750102<, 0.4625010

25 0.437500926 0.412500927 0.387500828 0.3625006

AIRCRAFT CONPANY T_O-DI_IEHSIOHAL POTENTIAL

NACA 0012 : EXAMPLE 1

ALPHA O = -0.000010

CHORD =/ 1.000000

NACA 0012 : EXAMPLE 1

Y-0.0009536-0.0027575-0.0044365-0.0067700-0.0100112-0.0133284-0.0164470-0.0194323-0.0223233-0.0251359-0.0278768-0.0305473-0.0331<,27-0.0356590

-0 0380946-00qO4q<,4

-0 0<,27021-0 0448624-0 0_69188-0 0_88641-0 0506920-0 0523956-0 0539657-0.0553936-0.0566678-O.0577752-0,0587010-0.0594260

FLGM PROGRAM

NO. OF BODIES 1

TOTAL ELEMENTS 138

NO. OF ELEMENTS 138

S VT CP J0.0024939 -0.8268576 0.3163066 10.0074755 -0.8886778 0.2102517 20.0124468 -0.9189486 0.1555335 30.0198878 -0.9_51062 0.1067743 40.0310313 -0.9680851 0.0628113 50.0433954 -0.9839670 0.0318090 60.0557466 -0.9951780 0.0096207 70.0680897 -1,0043_50 -0.0087891 80.0804271 -1.0128355 -0.0258350 90.0927601 -1.0208483 -0.0421305 100.1050892 -1.0285645 -0.0579443 110.1174146 -1.0361195 -0.0735426 120.1297361 -1.0_3<,093 -0.0887022 130.1420537 -1.0504131 -0.1033669 1<,

0.15_3674 -1.0573263 -0.1179380 150.1666770 -1.0641356 -0.1323843 16

0.1789825 -1.0707989 -0.1466093 170,1912838 -1.0773840 -0.1607561 18

0.2035809 -1.0838785 -0.1747923 190.2158735 -1.0902719 -0.1886921 200.2281619 -1.0966110 -0.2025557 210.2404459 -1.1029654 -0.2165318 220,2527257 -1.1092901 -0.2305241 230.2650014 -1.1156693 -0.2447176 2_0.2772729 -1.1220798 -0.2590628 250.2895406 -1.1285248 -0.2735682 260.3018047 -1.1350374 -0.2883091 270.3140656 -1.1414566 -0.3029222 28

I

101102

I03104

105106

107108

109110

Ill112

113114

115116

117118

119120121

122123

124125

126127

128129

130131

152133

13q135

136137138

139

X(I) Y(I}

0.I000000 0.04700400.1250000 0.0507320

0.1500000 0.05363600.1750000 0.0558790

0.2000000 0.05757000.2250000 0.05879400.2500000 0.05961200.2750000 0.0600760

0 3000000 0.06022600 3250000 0.06009400 3500000 0.0597070

0 3750000 0.0590900

0 4000000 0.05826200 <,250000 0.0572<,30

0 <,500000 0.05605100 4750000 0.05<,69500 5000000 0.05319800 5250000 0.0515600

0 5500000 0.04979300 5750000 0.0<,790600 6000000 0.0<,590_00 6250000 0.0<,379500 6500000 0.0q15850

0.6750000 0.0_928100.7000000 0.0368870

0.7250000 0.0344110

0.7500000 0.03185500.7750000 0,02922100.8000000 0.02651500.8250000 0.02373900.8500000 0.02088800.8750000 0.01795300.9000000 0.01_9080

0.9250000 0.01170000.9500000 0.00825100.9700000 0.00523900.9800000 0.00361100.9899999 0.00187401.0000000 0.0000000

ORIGINAL PAGE IS

OF POOR Q_JALITY

SIGMA VN-0,0131<,Z 0.000003

-0.013130 0.00000<,-0.012671 0.000004-0.012001 0.00000<,-0.011208 0.00000<,-0.010560 0.000003

-0.010141 0.000003-0.009908 0.000002-0.009761 0.000001-0.009632 0.000001-0.009518 0.000001

-0,009385 0.000001-0.009215 0.000001

-0.009038 0.000001-0.008855 0.000001-0.008629 0.000001

-0.008389 0.000001-0.008116 0.000001

-0.007818 0.000001-0.007483 0.000001-0.007134 0.000001-0.0067<,5 0.000001-0.006321 0.000000

-0.005863 0.000000-0.0053<,0 0.000000-0.004772 0.000000-0.004120 0.000000-0.003377 0.000000

Figure 6.1:

b. Surface flow characteristics

Printed output for the potential flow calculations in Example

71

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I

303132

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78

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9293

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100101

102103

104105

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129130131

132

133

X0.33750040.31250010.28749970.262¢9920.23749840.212_9730.18749560.16249320.137089_0.11248320.09499600.08499480.0749931

0.06499050.05_9870

3.0G71957

_.03/_9360 032_920

0.02;_920.022_8320.017_724

0.01245260.0087273

0.00620750.0043571

0.00309790.00237360.002123_0.0018732

0.00162300.0013727O.0O112220.0009367

0.00081160.00068640.00056120.00043590.00031010.00018300.00003370.00003370.0001830

0,00031010.0000359

0.00056120.00068640.00081160.00093670.00112220.0013727

0.00162300.0018732

0,002123_0.0023736

0,00309/90.00_3571

0.00620750.008/2730.012452b

0.017_72#0.0224832

0.027_8920.03249200.03749_60.0_249070.047_9570.05498700.06499050.07499310.08499480.09499600.11248320.1374894

0.16249320.18709560.212_9730.237498_0.262_992

0.2_749970.31250010.337500_0.36250060.38750080.41250090.43750090.4625010

0.48750100.5125009

0.53750100.56250060.58;50070.61250080.63750080.66250090&875005).7125006

0.73750070.76250380.78750080.81250050.83750070.86250110.88750180.9125030

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0.00081820.00199_80.00265100.0032039

0.00369680.0041473

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0.01377150.0161891

0.0190892O.0223O86

0.02501160.02737010.02949850.031_4620.0332373

0.03489130.03714990.03982430.0421762

0.04_26620.0461379

0.04898000.05227490.05_83230.0567876

0.05823630.05925030.05988560.06018820.06019350.05993080.059_2600.05870100.05777520.0566678

0.05539360.05396570.05239560.05069200.04886410.0469188

0.04486200,0q270210.040444q0.03809_60.0356590

0.03314270.0305_73

0.02787680,0251359

O.O2232330.0194323

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0.52268640.52531770.52792190.53050410,53433990.53941630.54445370.5_946280.554_5090.56313630.5755014

0.38782330.6001178

0.61239500.62466140.63692130.64917830.661¢3420.67369070.68594900.6982099O.71O47400.72274170.73501330.74728890.75956880.77185280.78414110.79643380.80873080.82103220.83333770.84564730.85796090.87027850.88260010.89492540.9072545

0.91958700.9319250

0.94426800.9566193

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0.78009530.87690520.95306001.01516531.06777101.098_2781.11550241.1306782

1.14439201.15531831.16368871.17291831.1808882

1.18511301.1872892

1.18830391.18918991.18857481.18592831.18199831.17719271.17183591.16608141.16014391.15405271.14779571.1414566

1.13503741.12852481.12208081.11566931.10929011.10296541.09661101.09027191.08387851.0773830

1.07079891.06413561 0573254I 05041311 04340931 03611951 02856451 0208483I 01283451 00438500 99517760 9839664

CP-0.31743h3-0.3318377-0.3459358

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0.09167650.23103860.3914513

0.53899500.63979080.6751234

0.7117984

0.75011100.78828050.82712840.85628710.87563190.89501590.91463960.9336185

0.95272130.971375_0.99478220.99478210.97137570.95272200.93361940.9144407O.89501710.87563400.85628820.82712940.78828140.75011270.71179940.67512410.63979250.53899530.39145140.23103730.0916766

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0.00962160.0318101

J9

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4O

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9293

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-0 oo167_-0 000_8_0 000589

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O.O333880,035952

0.038617O.042161

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0 0977820 0975120 0971540 096394o 0953170 0941720 092791.

0 0910790 0902_0

0 0860450 0791970 0707700 O624040 0551160 0079860.0_21610.0386170.0359510.0333880.0309820.02577_0.025912

0.O225930.0198880.0176600.0158020.013169

O.0100150.0074570.0053040.0034970.0019310.000589

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VH0.000000o.o0o0oo

o.0000000.00000o

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0.0000000.000001

0.000001O.O00001O.O00001

O.OOOO020.000002O.0OOOO20.0000020 0000020 000002

0 0000020 0000020 0000020 0000020 000003

-0 000003-0 000009-0 000026-0 000027-0 000013-0 0000030 O0OOO1

0 0000020 0000020 O000010 0000010 0000020.0000010.000001

O.OOOO020.000001

0,000001

0.0000020 000001

0 000000-0 000000-0 000001

-0 000002-0 000002

-0 000003-0 000003

-0 000003-0 000003-0 000003-0 000003-0 000003-0 000004-0 000003-0 000004-0 000003

-0,000002-0.000002-0.000002

0.0000000.0000000.0000000.0000000.000000

0.0000000.0000000.0000000,000000

0.0000000.0000000.O00OOOO.O00001O.OOOO01

0.000001O.O000010.000001

0.000001

0.000001O.O000010.0000010.000001

O.0OOOO10.000001

0.0000010.000001

0.0000010.000001

0.000001

Surface flow characteristics (continued)

Figure 6.1: continuedORIGINAL PAGE _S

OF POOR QUALITY

72

Page 81: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

L3_ 0 _37504_ 0.0100112[_5 0 05000_5 0.00677801_6 0q75UUt8 0.004436513/ 0.9850022 0.0027575130 0.9950050 0.0009536

INTEGRATED VALUES

CY = 0.00000 CX = 0.00010

(:L = 0.00000 CD = 0.00010

PARABOLIC IHTEGRATION

INTEGRATED VALUES

CY : 0.00000 CX : 0.0001%

CL = 0.00000 CD = 0.0001_

TOTAL CM = 0.00000

TOTAL CM : -0.00000 (PARABOLIC)

S0.96898320.98012670.98756760.99253880.997520_

CM = 0.00000

CM : -0.00000

VT0.96808460.94510600.9189_850.88867680.8268565

CP0.06281230.10577470.15553370.21025370.316_08_

J SIGMA VN13_ -0.01120_ 0.000004135 -0,0IZ001 0.000004136 -0.01267l 0.00000_137 -0.013130 0.000005

138 -0,0131qZ 0.00000q

ORIGINAL PACi_ 19

OF POOR QUALITY

Surface flow characteristics (continued)

Figure 6.1: Concluded

THE PARTICLES ARE RELEASED FROM X = -1.26000E 00WHICH IS OBTAINED AT TilE I LOOP OF 50 LOOPS

GEOMETRY CHARACTERISTICS:

LEADING EDGE (X,Y) -2.0000E-033.0200E-01

TRAILING EDGE (X,Y) / _.0136E-02TIIICKNESSCHORD 5.0000E-01ANGLE OF ATTACK 0.0000

U?PE_ BOUNDARY 2.2075E-02LCWER BOUNDARY -2.2075E-02

PARTICLE TRAJECTORY DATA:

0.00000.0000

THE PARTICLES ARE RELEASED IN EQUILIBRIUM WITH THE AIR

PARTICLE INITIAL INITIAL PARTICLE PITCII PIT GRAVT ERROR

DIAMETER VX VY AOA ANGLE DOT CONST CRITERIA(MICRONS) (M/S) (M/S) (DEGREES) (DEGREES) (DEG/SEC) (M/S_W2)

20.00 0.00 0.00 0.00 0.00 0.00 0.00 5.00E-05

THE PARTICLES OF SIZE 20.00COHTAIN 1.0000 OF THE TOTAL MASS

X0 Y0 XP YP S DT NSTP-1.2599993 0.0150000 OUT OF RANGE 0.0471370 0.022q023 3.6qq0E-05 58-1.2599993 -0.0150000 OUT OF RANGE 0,0_73017 -0.022q552 3.5855E-05 67

YOMAX= 1.5000E-02 YOMIN= -1.5000E-02

-1.2599993 0.0000000 HIT BODY AT -0.0019999 0.0000010 0.0000011 5.9902E-06 _6-1.2599993 0.0075000 NIT BODY AT 0.01252q9 0.0100_23 0.0197897 1.1801E-05 67

-1.2599993 0.0112500 OUT OF RAH_E 0.0732779 0.0228669 q.9098E-05 7q

-1.2599993 0.0093750 OUT OF RANGE 0.08q6801 0.0229987 6.0772E-05 83-1.2599993 0,008q375 HIT BODY AT 0.022720q 0.0127862 0.030566q 1.7692E-05 65-1.2599993 0.0089062 OUT OF RANGE 0.0793677 0.0221173 5.7872E-05 0_-1.2599993 0.0086719 OUT OF RANGE 0.0863379 0.0227919 5.558_E-05 83

-1.2599993 0.00855_7 OUT OF RANGE 0.0862296 0.0227190 5.9_60E-05 99-1.2599993 0,008q961 NIT BODY AT 0.0258700 0.013_200 0.0337822 2._208E-05 69-1.2599993 -0.0032520 HIT BODY AT 0.0000620 -0.0037906 -0.0055256 5.B16qE-06 59-1.2599993 -0.0091260 OUT OF RANGE 0.0826181 -0.022627_ 5.8351E-05 83-1.2599993 -0.0061890 HIT BODY AT 0.00636_5 -0.0077377 -0.0133298 9.1509E-06 61

-1.2599993 -0.0076575 HIT BODY AT 0.0133570 -0.010373q -0.0208795 1.1755E-05 65

-1.2599993 -0.0083917 HIT BODY AT 0.0216_31 -0.0125515 -0,029_638 1.9979E-05 69-1.2599993 -0.0087588 OUT OF RANGE 0.0826917 -0.022_2_2 _.8719E-05 87-1.2599993 -0.0085753 OUT OF RANGE 0.0875171 -0.0228_87 7.0857E-05 86-1.2599993 -0.008q855 HIT BODY AT 0.0237963 -0.0150158 -0.0316695 1.7371E-05 74

UPPER SURFACE LIMIT LOWER SURFACE LIMIT

YOU SU Y0L SL

0.Bq96E-02 0.3378E-01 -0.8%83E-02 -0.3167E-01

-1.2599993 0.0076_71 HIT BODY AT 0.0132636 0.0103qq8 0.0207819 1.1751E-05 69

Figure 6.2: Printed output for the individual particle trajectory calculations

in Example 1.

"73

Page 82: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

×0 Y0

-1.2599973 0.0065556 HIT BODy AT-1.2599993 0.0054640 HIT BODY AT-1.2599993 0.00_3725 HIT BODY AT-1.2599993 0.0032809 HIT BODY AT

-1,2599995 0.0021896 HIT BODY AT-|.2599993 0.0010978 HIT BODY _T-1.2599993 0.0000063 HIT BODY _T

-1.2599993 -0.0010852 flIT BODY AT

-1.2599993 -0.0021768 HIT BODY AT

-1.2599993 -0.0032683 HIT BODY AT

-1.2599993 -0.0063599 HIT BODY AT-1.2599993 -0.005651_ NIT BODY AT

-i,2599993 -0.0065q30 HIT BODY AT

-i 2599993 -0.00763q5 HIT BODY AT

XP

0 0077701

0 0042313

0 00182710 0000979

-0 001039_

-0 00171O8

-0 001999q

-0 0017167-0.0010524

0.00007760.00179590.00_1859

0.0077176

0.01320q7

YP

0.00836890.00667970.00520050.00382380.00251880.00125620.0000057

-0.0012406-0.00250_9-0.00380_9-0.0051801-0.0066553

-0.0083265-0.0103267

S

0 01_8929

0 0109037

0 00800550 00557q5

0 0035691

0 00179990.0000057

-0.0017832-0.0035500-0.0055467-0.0079682-0.0108521

-0.01_8358-0.0207203

Figure 6.2: Concluded

DT

8.683OE-06

7 9091E-06

6 0560E-066 136_E-06

5 9198E-06

6 98_3E-06

5 9947E-067 I0_3E-06

6 17qqE-06

6._569E-06

7.3536E-06

9.0981E-068.6736E-06

1.73_6E-05

NSTP57

_652

5_

6O

_647

43

46

_9

61

5?

57

Y0 VS S DATA FOR DROPLET DIAMETER =

17 POINTS HAVE BEEN CALCULATED

I S

1 0.0537822 0.0207823 0.016893

0.0109065 0.0080056 0.0055757 0.0055698 0.001B009 0 000006

10 -0 00178311 -0 503550

12 -0 00556713 -0 00796814 -0 010852!5 -0 016836

16 -0 020720i7 -0 031670

Y0

0,008¢960.0076470.0065560,005¢640.0043720 0032810 0021890 0010980 000006

-0 001085

-0 002177

-0 003268-0 00_360-0 005_51-0 006543

-0 007655-0 008683

20.00000 MICRONS

a. Calculate Yo vs s points

ORIGINAL PAGE IS

OF POOR QUALITY

CALCULATED

SEG

I -02 -0

5 -0

4

56

7

89

!0

11

12

13

1516

!7

19

20

2122

23

2q

25

LOCAL COLLECTION EFFICIENCY FOR DROPLET DIAMETER s

S309069306890301823

-0 2972q5-0 290605-0 282821-0 275269-0 _67686-0 260129-0.252576-0.245025-0.237_77-0.229931-0.222386-0.21484;-0,20730_-0 199766-0 192231

-0 186697-0 177165-0 169635-0 162108

-0 156582-0 167058-0 139536

_ETA SEG S0.000000 26 -0.1320140.000000 27 -0.1244940.000000 28 -0.1169740.000000 29 -0.109_540.000000 30 -0.1019330.000000 31 -0.09_4100.000000 32 -0.0868840.000000 33 -0.0793530.000000 34 -0.0718140.000000 35 -0.06426_0.000000 36 -0.056696

0.000000 37 -0.0691020.000000 38 -0.0_14820.000000 39 -0.0361130.000000 40 -0,035010

0.000000 61 -0.0298990.000000 _2 -0.026761

0.000000 _3 -0.0235970.000000 4_ -0.0211920.000000 65 -0.0195560.000000 46 -0.0179110.000000 67 -0.0162;20.000000 48 -0,0145600.000000 _9 -0.0127860.000000 50 -0.010945

20.00000 MICRONS

BETA SEG0.000000 51

0.000000 52

0.000000 53

0.000000 540.000000 55

0.000000 56

0.000000 570.000000 580.000000 590.000000 60

0.000000 610.000000 620.000000 630.000000 660.000000 65

0.023592 660.067630 670.11202_ 680.1%5775 69

0 168733 700 191828 710 215251 72

0 251020 730 28907_ 760 528992 75

S-0.009002-0.007390-0.006131-0.005052-0.00ql9q-0.003623

-0.005371-0.00316_

-0.002904-0.002669

-0.002381-0.002162-0.001995-0.001826

-0.001663

-0.001_2

-0.001212-0 000895-0 000351

0 000351

0 0008950 001212

0 001_2

0 0016q_

0 001826

b. Local collection efficiency for each body segment.

Figure 6.3: Summary of the particle trajectory and local collection efficiency

calculations in Example 1.

BETA0.3876320._%08360.q_3091

0.5225690.5578310.581160

0.5813000.5854090.5897590.59_386

0.5992250,6032080.6062200.60928_0.6139150,613387

0.612782

0.6119500.610521

0.61045_

0.6116820.6120320.612518

0,612899

0.608128

74

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SEG767778798O8182838_85868788

909192939495969793

:O2!03

105106107

S0.0019950.0021620.0023310.0026090.0029040.0031440.0033710.0036280.004194

0.0050520.0061310.0073900.00900200109_50.0127860.0145400 0162_20 0179110 0195560 021192

0 0235970 026761

0 029399

0 033010

0 C36113

0 0_I_820 0_9102

0.0_66960.06_2640.07131_

0.0793530.08638_

BETA0.6050380.6020000.5979820.5931020.5884350.5840470.5799040.5804440.5571250.5218460.4820570.440096

0.3872850.328975

0.289_06

0.2516B3

0 2158060 1928100 170136

0 I07597

0 I14_61

0 0708770 0276420 0000000 0000000 0000000.0000000.0000000.0000000.0000000.0000000.000000

SEG108

109

II0Iii

112

113

114

115

116117

118119

120

121

122123

124

125

126

127128

129

130

131

132133

134

135

136

137138

S0.0944100.1019530.109#5_0.1169740.12_4940.132014

0.139536

0.1670580 1565820 162108

0 1696350 177165

0 184697

0 192231

0 199766

0.207306

0.2168440,222386

0.229931

0.237_77

0.2650250.2525760.2601290.2676860.2752_90.2828210.290005

0.297205

0.501823

0.3048900.509069

BETA0.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000 0000000 0000000 0000000 0000000 0000000 0000000 000000

0 0000000 0000000 0000000 0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.000000

b. Local collectionefficiencyfor each body segment

Figure 6.3: Concluded

OR/GINAE PAGE IS

OF POOR QUALITY

(continued).

SEG SI -0.30721E 002 -0.30016E 003 -0.30112E 00

-0.29656E 005 -0.28970E O06 -0.282|8_ O07 -0.27q62E O08 -0.26707E O0

9 -0.25952E 00

I0 -0 25197E O0

Ii -0 2_2E 0012 -0 23638E 0013 -0 2293_E 00I_ -0 221_0E 00

15 -0 21_27E 00

16 -0 20673E 00

17 -0 19920E 0018 -0 19168E 00

19 -0,18615E 0020 -0.17665E 0021 -0.16911E 0022 -0.16159E 00

23 -0.15608E 0024 -0.1_656E 0025 -0.13905E 0026 -0.13155E 0027 -0.12404E O028 -0.I1656E 0029 -0.10904E 0030 -0.10156E 0031 -0.9_037E-0152 -0 86537E-0133 -0 79034E-0136 -0 71528E-0135 -0 66015E-0136 -0 56691E-0137 -0 _8951E-0138 -0 q138qE-01

39 -0 36069E-01_0 -0 35011E-01ql -0.29968E-01_2 -0.26853E-0143 -0.23729E-016_ -0.21363E-01

05 "-0.19763E-01

QCOND

0.000000.000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

0 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.00000O.O00OO0.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

MDOTC MDOTRI0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

J 0.00000 0.00000

0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0,000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

0.00000 0.00000

0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

0.46756E-05 0.000000.13490E-04 0.00000

0.22546E-04 0.000000.1q801E-04 0.000000.17264E-04 0.00000

HDOTE

0.00000

0.000000.000000.00000

0.00000

0.000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 00000

0 000000 000000 000000.000000.000000.000000.000000.000000.00000

0.93270E-050.30625E-050.35536£-050.19768E-050.21182E-05

HDOTTI0.000000.000000.000000.000000.000000,000000,000000.000000,000000,000000.000000.000000,00000

0 000000 000000 000000 00000

0 000000 000000 000000 000000 000000 000000 00000

0 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

0._6756E-050.13690E-060.225_6E-000.16801E-060.1726_E-06

HDOTT

0.00000

0.000000 00000

0 00000

0 00000

0 000000 0000O

0 000000 000000 000000.000000.000000.00000

0.000000.00000

0.00OOO

0.00OOO

0.000000.0OO000.000000.000000.000000.00000

0.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 00000

0 00000

0 OO0OO0 000000 000000 000000 00000

0.10_28E-0_0.18993E-000.12827E-040.15106E-0_

a. Icing condition and summary of ice accretion data

Figure 6.4: Printed output from the ice accretion calculations in Example

1. 75

Page 84: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

5EG_6¢7

48¢9SO515253

55's6575859

6061625364SS_66768697071":2737,q75;67"7879808182838¢8586878889909192939_9S96979899

].00101102103

105106107108109110111112113

11611711811912012112212312c+125126J271281291.5013113213313c+135136137138

S-0.181_6E-01-0.16506E-01-0.1_833E-01-0.13110E-01-0.11302E-01-0.93693E-02-0.77677E-02-0.6_879E-02-0.53333E-02-0._3923E-02-0.37712E-02-0.36932£-02-0.32617£-02-0.29800Eo02

-0.270_8£-02-0.26173£-02-0.21866£-02-0.20]37E-02-0,183)3E-02-0.16529E-02-0.16501_-02-0.12199E-02

-0.91868E-03-0.37066E-03

3 3706_E-030 91867E-030 12199E-020 1_500E-020 16528E-020 18392E-02

0 20136E-02

0 21865E-02

0.2_171E-02

0.27047E-020.29798E-020.3ZqlSE-020.3_930£-020.37710£-020.63922E-020.53337E-02O.64871£-020.77652£-020.93666E-020.11299E-010.13107£-010.16830E-010.16§03E-010.18143E-010 19759£-010 21360£-010 23726E-010 26851E-010 299q6E-010 33015E-010 36067E-010 _1382E-010 489_9E-01

0 56489E-01

0.6;013[-01

0.7152GE-010.79032E-010.86535E-010.96035E-010.1015_£ 000.1090_E 000.11656E 000.12_0_E 000.13155£ O00.13905E O00.16656E O00.15_07E O00.16159E 000.16911E 000.17663E 000.18_15E 000.19167E 000.19920E O00,20673E 00

0.21627E 000.22185£ 000.22936E 000.23688E 000.2_6_2E 00

O.25197£ 000,25951E 000.26706£ 000.27_62E 000.28218£ 000.2897;E 000.29656E 000.30112E 000.30_16E 000.30721E 00

QCOND0.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.00000

0.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000600.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

_DOTC0.19810E-040.22683E-0fi0.26596E-060.31279E-060.36889E-060._5990E-0_0.28238E-0_0.3_3_2E-0q0.21231E-0_0.26185E-0_0.61258E-050.6q190E-050.68230E-050.73125£-050.78811E-050.86295£-050.46692E-050._9695E-050.53020E-050.57658E-050.63131E-05

0.71395E-050.86999E-050.19336E-0_0.1933_E-060.86932£-050.71313E-050.63062E-050.57563E-050.52920E-050 69399E-050 _6598E-050 86117E-050 78641E-050 72961E-050 68071E-05

0 6q036E-050 61185E-050.26151E-040.21202E-0q0.3q268E-0q0.28191E-04O._§9q9E-0_0.36&87E-0q0.31315E-0q0.26666E-0_0.225_1E-0_0.19911E-0_0.17k07E-0_0.1_986E-040.23037E-0_0.1q138E-0_0.Sq782E-05

0.000000.000000.000000.000000.000000.00000O.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

MDOTRI

0.000000.000000.000000.000000.000000.000000.000000.00000

0.18_32E-050.85131£-050 93358E-050 992_6E-050 10286E-0_0 10377£-0_0 10151E-0_0 95637E-050 910_8E-050.85090E-050.777O8£-050.68596E-050.58027E-050.q5832E-050.31_32E-05

0.000000.00000

0.31_13E-05

0._5755E-050.57880E-050.68372E-050.77_01E-050.86697E-05

0.90572E-050.95080E-050.10080E-0q0.10292E-0_0.10186E-0_0.98116E-050.92095E-050.83806E-050.16818E-0§

0.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000,000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

_DOTE

0.22692E-050.24326E-050.26663E-050.29390E-050.32710E-050.3773_E-050.21648E-050.2_859£-050.15_91E-050.20664E-050._3172E-060._3325£-060.q_l�SE-060._5292E-06

0 _6528E-060 _8563E-060 25283£-060 26031E-060 27181E-060 28796E-060 31115E-06

0 35022E-06

0.63012E-060.95677E-060.95677E-060._3012£-060.35022E-060.31115E-060.28796E-060.27181E-060.26031E-060.25283E-060.qSS63E-060._6528E-060._5292E-060._191£-060.q3325E-060.q3172E-060.2066_E-050 15393E-050 2_826E-050 21627E-050 37718E-050 32709£-050 29_05E-050 26693E-050 2_350E-050 22734E-050.212_2£-050.19825E-050.35737£-050.30885E-050.9327_E-05

0 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.000000,000000.000000.00000

0.00000

_DOTTI0.19&IOE-040.22_83E-0_0.26596E-040.31279E-0q0.36889E-0_0._5990E-060 28238E-0_0 3q362E-0_

0 2307_E-0q0 3q698E-0_0 15662E-0_0 1634qE-0_0 17109E-0_0 17690E-0_0.18032_-0_0 18193E-0_

0 1377_£-040 13459E-0_0 13073E-0_0 12625E-06

0 12116E-06

0 I1723E-0_

0 118G3E-060 19336E-060 19336E-06

0 I1835E-04

0 11707E-0_0 12092E-0_

0 12593E-Oq0 13032£-0_0 13_IOE-06

0.13717_-06

0.18120E-0_

0.179_q£-060.17588£-0_0.16993E-060.16215£-0_0.15328£-040.36532E-0_0.22883E-040.3_268E-0_0.28191E-0_0._5969E-0_0.36887E-0_0.31315E-0_0.26666E-060.22541E-0_0.19911£-0_

0.17_07E-0_

0.1_986E-040.23037E-0_0.1_138E-0_0.56782E-05

O.000OO0.000000.000000.000000.000000.000000.000000 00O0O0 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.00000

0.000000 000000 000000 00000

0 000000 00000

0 000000 000000 000000 000000.000000.000000.000000.000000.000000.000000.00000

0.00000

0.00000

_DOTT

0.17560E-060.20050E-0q0.23930E-060.283_0E-0_0.33618E-0q0.42217E-0_0.2607_£-0_0.31856E-0_0.21525E-0q0.32631E-0_0.15030E-0_0.15910E-0_0.16667E-060.17237E-0_0.17567E-0_

0 17708E-0_

0 13521E-0q

0 13198E°0_0 12801E-0_

0 12337E-OG

0 I1805E-0_

0 11372E-06

0 11613E-060 18379E-06

0 18377£-06

0 II_04E-0_

0 I1357E-0G

0 I1781E-06

0 12305E-O_0 12760_-06

0 131_9E-0_

0 13_6_E-0_

0 1763_£-0_

0 17679£-0_

0 17135E-0_0 16551E-0_

0.15782E-0_

0.I_896_-0q0.32665E-0_0.2136_E-0_

0,31786£-06

0.26028E-0q

0,62177E-060.33616E-0_0.2837_E-0_0.23997E-0_0,20106E-0_0.17638E-060.15283E-040.1300_E-0q0,19q63E-0q

0.11069E-060.000000.000000.000000.000000.000000.00000

0.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

0.000000.000000.000000.000000.000000.000000.00000

0.00000

0.000000 00000

0 OOO0O

0 00000

0 000000 00000

0 00000

0 000000 000000 000000.000000.000000.000000.000000.000000.00000

b. Calculated surface ch_acteristics (continued)

Figure 6.4: continued

76

ORIGINAL PAGE IS

OF POOR QUALITY

Page 85: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

HACA 0012 : EXAMPLE 1

ICING CONDITIOH:

STATIC TEMPERATURE (C)STATIC PRESSURE (PA)VELOCITY (M/S)LWC (GIM"_3)DROPLET D_AMETER (_ICROHS)

: T_E = 60.000 SEC

260.5590748.00

129.000.50

20.00

ICE ACCRETION DATA:

STAGNATIOH POINTTRAt4SITIOt4 POINTS (LOWER,UPPER)ICIHG LIMITS (LOWER,UPPER)HUMBER OF POINTSNUMBER OF SEGMENTS ADDED

7O6842

1390

7197

OmCfNALPAGE ;sOFPOORQUAL;TY

SEG X Y1 0.30000E 00 0.000002 0.29700E 00 -0.56220E-033 0.29400E 00 -0.10833E-02

0.29100E 00 -0.15717E-025 0.28500E 00 -0.24753E-026 0.27750E 00 -0.35100E-027 0.27000E 00 -0.q_72_E-028 0.26250E 00 -0.53859E-029 0.25500E 00 -0.6266_E-02

10 0.24750E 00 -0.71217E-0211 0.24000E 00 -0.795_5E-0212 0.23250E 00 -0.87663E-0213 0.22500E 00 -0.9§565E-0214 0.21750E 00 -0.10323E-0115 0.21000E 00 -0.11066E-0116 0.20250E 00 -0.1178_E-0117 0.19500E 00 -0.12475E-0118 0.18750E 00 -0.13138E-0119 0.18000E 00 -0.13771E-0120 0.17250E 00 -0.1_372E-0121 0.16500E 00 -0.1_938E-0122 0.15750E 00 -0.15468E-0123 0.15000E 00 -0.15959E-0124 0.14250E 00 -0.16409E-0125 0.13500E 00 -0.16815E-0126 0.12750E 00 -0.17173E-0127 0.12000E 00 -0.17479E-0128 0.11250E 00 -0.17727E-0129 0.10500E 00 -0.17912E-0130 0.97500E-01 -0.18028E-0131 0.900_0E-01 -0.18068E-0132 0.82500E-01 -0.18023E-0133 0.75000E-01 -0.1788_E-0134 0.67500E-01 -0.17638E-0135 0.60000E-01 -0.17271E-0136 0.52500E-01 -0.16764E-0137 0.45000E-01 -0.16091E-0138 0.37500E-01 -0.15220E-0139 0.30000E-Of -0.14101E-0140 0.27000E-01 -0.13568E-0141 0.2_000E-01 -0.12976E-0142 0.20965E-01 -0.124§0E-0143 0.1790_E-01 -0.11926E-0144 0.1_8_2E-01 -0.11223E-01_5 0.13291E-01 -0.1085_E-0146 0.11743E-01 -0.10_25E-0147 0.10187E-01 -0.97488E-0248 0.86129E-02 -0.9_430E-02_9 0.70109E-02 -0.88981E-0250 0.53760E-02 -0.82622E-0251 0.36757E-02 -0.75051E-0252 0.19168E-02 -0.65439E-02$3 0.89327E-03 -0.59196E-025_ -0.20987E-03 -0.51230E-0255 -0.10241E-02 -0.46363E-0256 -0.15952E-02 -0.38979E-0257 -0.16134E-02 -0.35899E-0258 -0.16399E-02 -0.33_39E-0259 -0.167qBE-OZ -0.30707E-OZ60 -0.17045E-02 -0.28245E-0261 -0.17332E-02 -0.25435E-0262 -0.17677E-02 -0.22528E-0263 -0.17728E-02 -0.20803E-026_ -0.17852E-02 -0.19116E-0265 -0.18036E-02 -0.17328E-02

s-0.30721E 00-0.30416E 00-0.30112E 00-0.29656E 00-0.28974E 00-0.28218E 00-0.27_62E 00-0.26707E 00-0.25952E 00-0.25197E 00-0.24_42E 00-0.23688E 00-0.2293_E 00-0.22180E 00-0.21_27E 00-0.20673E 00-0.19920E 00-0.19168E 00-0.18415E 00-0.17663E 00-0.16911E 00-0.16159E 00-0.15_08E 00-0.14656E 00-0.13905E 00-0.13155E 00-0.1240_E 00-0.11654E 00-0.1090;E 00-0.10154E 00-0.94037E-01-0.86537E-01-0.79034E-01-0.71528E-01-0.6_015E-01-0.56;91E-01-0._8951E-01-0.413&_E-01-0.36069E-01-0.33017E-01-0.29948E-01-0.26853E-01-0.23729E-01-0.21363E-01-0.19763E-01-0.18146E-01-0.16506E-01-0.1_833E-01-0.13110E-01-0.11302E-01-0.93693E-02-0.77677E-02-0.64879E-02-0.53333E-02-0,43923E-02-0.37712E-02-0.3_932E-02-0.32;17E-02-0.2_lgQE-g2-0.27048E-02-0.24173E-02-0.21846E-02-0.20137E-02-0.18393E-02-0;.16S29E-02

VE0.10282E0.113q7E0.11731E0.12094E0.12_23E0.12655E0.12819E0.12954E0.13075E0.13189E0.13298E0.13q0;E0.13507E0.13607E0.13704E0 13801E0 13895E0 13989E0 lq081E0 14171E0 14262E0 14352E0 1_442Eo 1_533E0 14624E0 14715E0 1_806E0.1_896E0.1_985E0.15072E0.15157E0.15237E0.15314E0.1§383E0.15_IE0.15483E0.15500E0.15;78E0.15_26E0.15380E0 15308E0 15196E0 15022E0 1_830E0 1_666E0 l_60E0 1_207E0 13891E0 13_73E0 12866EO 1195_E0 10892E0 98295E0.87_17E0.77850E0,71259E0.682_8E0.6559_E0.62800E0.59880E0.56913E0.54569E0.52861E0.51209E0.49522E

TE03 0.26357E 0303 0.26242E 0303 0.26198E 0303 0.26155E 0303 0.26115E 0303 0.26086E 0303 0.26065E 0303 0.260_8E 0303 0.26032E 0303 0.26017E 0303 0.26003E 0303 0.25989E 0303 0.25975E 0303 0.2§962E 0303 0.25949E 0303 0.2§93§E 0303 0.25922E 0303 0.25909E 0303 0.25896E 0303 0.25884E 0303 0.25871E 0303 0.25858E 0303 0.2§845E 0303 0.25832E 0303 0.25819E 0303 0.25806E 0303 0.25792E 0303 0.25779E 0303 0.25766E 0303 0.257_3E 0303 0.257_0E 0303 0.25728E 0303 0.25716E 0303 0.25706E 0303 0.25697E 0303 0.25690E 0303 0.25688E 0303 0.25691E 0303 0.25699E 0303 0.25706E 0303 0.25717E 0303 0.25734E 0303 0.25760E 0303 0.25789E 0303 0.25813E 0303 0.25843E 0303 0.25879E 0303 0.25923E 0303 0.25980E 0303 0.26059E 0303 0.26172E 0303 0.26293E 0302 0.26_02E 0302 0.26503E 0302 0.26_81E 0302 0.26630E 0302 0.26651E 0302 0.26669E 0302 0.26687E 0302 0.26704E 0302 0.26722E 0302 0.2673_E 0302 0.26744E 0302 0.26752E 030Z 0.26761E 03

PRESS0.94482E 050.93052E 050.92506E 050.91976E 050.91482E 050.91129E 050.90874E 050.90664E 0S0.90673E 050.90292E O50.90117E 050.89946E 050.89779E 050.89617E 050.89_57E 050.89298E 050.89141E 050.88985E 050._8831E 050.88677E 050.8852_E 050.88371E 050.88216E 050.88061E 050.87903E 050.87745E 050.87585E 0S0.87426E 050.87270E 050.87115E 050.86966E 050.86821E 050.86684E 050.86559E O50.86_54E 050.86379E 050.86348E 050.86388E 050.86482E 050t86565E 05

0.8669_E 050.86895E 050.87205E 050.87543E 050.87833E 050.88186E 050.88618E 0S0.891_8E 050.89835E 050 90801E 050 92182E 050 93678E 05o 95052E 050 9632_E 050 97328E 05o 97956E 050 98226E 050 98_54E 050 98685E 050 98915E 050 99139E 050 99308E O50 99427E 050 99538E O50 99648E 05

b. Calculated surface characteristics (continued)

Figure 6.4: continued

RA0 12469E 010 12334E 010 12282E 010 12231E 010 12185E 010 12151E 010 12127E 010 12107E 01o 12088E Olo 12071E 010 12054E 01o 12038E Olo 12022E 010 12007E 010 11991E 010 11976E 010 11961E 010 11946E 010 11931E 010 11917E 010 11902E 010 I1887E 010 I1872E 010 I1857E 010 I1842E 010 I1827E 010 IISIIE 010 I1796E 010 I1781E 010 I1766E 010 11752E 01o I1738E Ol0 I1725E 010 I1713E 010 I1702E 010 I1695E 010 I1692E 010 I1696E 01o 11705E 010 I1713E 010 11726E 010 117_5E 010 11775E 010 11807E 010 11835E 010 11869E 010 I1911E 010 I1962E 010 12027E 010 12120E 010.12251E 010.12393E 010.12522E 010.12642E 010.12736E 010.1279_E 010.12820E 010.12841E 010.12862E 010.12884E Ol0.12905E 010.12920E 010.12931E 010.129_2E 010.12952E 01

SEGLEHGTH0 30523E-020 30449E-020 30395E-020 60676E-020 75710E-020 75615E-020 75554E-020 75515E-020 75486E-020 75461E-020 75438E-02o 75ql_E-020 75391E-02o 75367E-02o 75343E-02o 7531_E-02o 75292E-020 752C6E'320 75240E-020 75214E-020 75187E-020 75160E-020 75135E-020 75110E-020 75085E-020 75062E-020 75041E-020 75023E-020 75009E-020 75002E-020 75001E-020 75012E-020 75041E-020 75089E-020 75171E-020 75301E-0Z0 75504E-020 75829E-020 30_69E-020 30580K-OZ0.30799E-020.3109_g-020.31386E-020.15939E-020.16068E-020.16265E-020.16§36E-020.1692].E-020.17543E-020.18612E-020.2004_E-020.11989E-020.13607E-020.94852E-030.93358E-030.30853E-030.24737E-030.25563E-030.26787E-030.28247E-030.29266E-030.17260E-030.16919E-030.17971_E-030.1931]E-03

77

Page 86: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

5EG

66676869707172737c_757677";8

8O8182838_8586878859909Z92939K,9596979899

10010110210310qI05106107108109110111112113

116117113

170121I:'2123

125125!,"7128129130

Z32].33134

136137138139

X

-0 18269E-02-0.18597E-02-0.19107E-02-0.19736E-02-0.202_3E-02-0.]9735E-02-0.1910_E-02-0.18593E-0Z-0.182_3E-02-0.I8030E-02-0.178_5E-02-0.17721E-02-0.17671£-02-0,17325E-02-0.]7038E-02

-0.167_0E-02-0.16391_-02-0.16129E-02_0.1_9_9E-02

-0.10159E-02-0,20030E-03

0.89589E-030.19182E-020.36761E-020.53757E-020.7010IE-020.86119E-020.10186E-0]0.lITtlE-010.13289E-01

0.1q839E-010.I7897E-01

0.2096qE-010.2_000E-0!0.27000E-010.30000E-010.37500E-010.q5000E-010.52500E-010.6O000E-010.67500E-010.75000E-010.82500E-010.90000E-01

0.97500E-010.10500E o00.11250E 000.1Z000E 00

0.12750E 000.13500E 000.16250E 00

0.15000E 000.15750E 000.16500E 003.17250E 00

0.18000E 00

0.18750E 000.19500E 000.20250E 000.21000E 000.21750E 000.22500E 000.23250E 000,2_000E 000.2_750E 000.25500E 000.26250E 000.27000E 000.27750E 000.2B§00E 000.29100E 000.29400E 000.29700E 000.30000E 00

Y

-0 15qlIE-02-0 13312E-02-0 10887E-02-0 73960E-03-0 12515E-080 73957E-030 I0886E-0Z0 13311E-02

0 IS_10E-020 17326E-020 19114E-020.20801E-020.22526E-020.25_32E-020,282q2E-020.30903E-020.33_35E-020.35896E-020.38977E-020._6303E-020.51156E-020.59169E-020.65_21E-020.750qSE-020.82628E-020.89000E-020.9qqSqE-020.99518E-020.I0q29E-010.10861E-010.11231E-010.1193BE-010.12_56E-010.12976E-010.13568E-010.1_101E-010.15220E-010.16091E-010.1676qE-010.17271E-010.17638E-010.178B_E-010.18023E-010.18068E-010.18028E-010.17912E-010.17727E-010.17_79E-010.17173E-010.16815E-01

0.16q09E-01

0.15959E-010 15;68E-010 1_938E-010 1_372E-010 13771E-010 13138E-010 I2_75E-010 l178qE-01

0 11066E-010 10323E-010 95565E-020.87663E-020.795_5E-020.71217E-020.6266_E-020.53859E-020._72_E-020.35100E-020.2_753E-020.1§717E-020.10833E-020.56220E-03

0.00000

S

-_.1_501E-02-0.12199E-02-0.91868E-03-0.37066E-03

0.37066E-030.91867E-030.12199E-020.1_500E-020.16528E-020.18392E-020.20136E-020.218_5E-020.26171E-020.270q7E-020.29798E-020.32_15E-020.3_930E-020.37710E-020._3922E-020.53337E-020.6_871E-020.77652E-020.9366_E-020.11299E-010.13107E-010.1_830E-010.16503E-010.181_3E-010.19759E-010.21360E-010.23726E-010.26BS1E-010.299_6E-010.33015E-010.36067E-010._13B2E-010._89q9E-010.§6qB9E-010.6_013E-010.71526E-010.79032E-010.86535E-010.9q035E-010.1015_E 000.1090_E 000.1165_E O00.12_0_E 000.13155E 000.13905E 000.I_656E 000.15q07E 000.16159E 000.16911E 000.17663E 000.18_15E 000.19167E 00

0.19920E 000 20673E 000 21_27E 000 22180E 0002293_E 000 2368BE 000 2_2E 000 25197E 000 25951E 000 26706E 000 27_62E 000 28218E 000 2897_E 000 296_6E 000 30112E 00

0 30_16E 000 30721E 00

0.00000

VE

0._7811E 020._6063E 020._066E O20._I8B7E 020.q1887E 020.q_066E 020.q6063E 020._7811E 020._9522E 020.51209E 020.52861E 020.54569E 02

0.56913E 020.59880E 020.62800E 020,65590E 020.682_8E 020.71259E 020.77550E 020.87_20E 020.gB295E 020.10892E 030.1195_E 030.12866E 030,13_73E O30.13891E 030,1_206E 030.1_59E 030.1466qE 030.1_830E 030.15022E 030.15196E 030.15308E 030.15380E 030.15qZ6E 030.15q78E 030.15500E 030.15483E 030.15qqlE 030.1§3B3E O30.1531_E 030.15237E 030.15157E 030.15072E 030.1_985E 030.16896E 030.1¢806E 030.1¢715E 030.1662qE 030.1;533E 030.1_2E 030.1;352E O30.1_262E 030.1qlTIE 030.1q081E 030.13989E 030.13895E 030.13801E 030.1370qE O30.13607E 030.13507E 030.13q0qE 050,13298E 030.13188E 050.13075E 030.12953E 030.12819E 050.1265_E 030.12q23E O30.1209qE O30.11731E 030.113_7E 030.10282E 03

0.00000

TE0.26769E0.26777E0.26786E0.26796E0.26796E0.26786E0.26777E0.26769E0.26761E0.26752E0.267_4E0.26735E0.26722E0.2670_E0.26687E

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0.00000

PRESS

03 0 99756E 05

03 0 99863E 05

03 0 99980E 05

03 0 100IOE 06

05 0 100]0E 0605 0 99980E 0505 0 99863E 0503 0 99756E 0503 0 996_8E 0503 0 99538E 0503 0 99_27E O5

03 0 99308E 05

05 0 99_39E 0505 0 98915E 0503 0 98685E 0503 0 98_5_E O5

03 0 98226E 0505 0 97956E 0503 0 97328E 0503 0 96323E 0503 0 95052E 0503 0 93678E 05

03 0 92182E 0503 0 90801E 0503 0.B9835E 0503 0.891_BE 05

03 0.88618E 05

03 0.88186E 0503 0.87B33E 0505 0.B?543E 0503 0.B7205E 0503 0.86895E 0503 0.B669_E 0503 0.86566E 0503 0.B6_B2E 0503 0.86388E 05

0.B63q8E 050.86379E 050.&6qSqE 050.86559E 050.B668_E 050.86B21E 050.86966E 05

0.B7115E 050.87270E 050.87_26E 050.87585E 050.877_5E 050.87903E 050.88061E 050.88216E 05

0.88371E 05

0.BB52_E 050.88677E 050._8831E 050.88985E 05

0.891_1E 050.89298E 050.B9457E 05

0.89617E 050.89779E 050.899_6E 050.90118E 050.90292E 050.90473E 050.9066_E 05

0.9087qE 050.91129E 050,91_82E 050.91976E 050.92506E 050.93052E 050.9qq82E 05

0.00000

RA

0 12962E 01

0 12972E 01

0 12983E 010 1299qE Ol

0 12994E 01

0 12983E 0l0 12972E 01

0 12962E 010 1295ZE 01

0 lZ9qZE 010 12931E 010 12920E 0l

0 2905E 01

0 1288_E 010 12862E 01

0 128_IE 01

0 12820E Ol0 1279_E 010 12736E 010 126_2E 010 12522E 010 12393E 010 _2251E 01

0 12120g 010 12027E 010 11962E 010 11911E 010 11869E 0l0 11835E 010 11807E 010 11775E 010 117q5E 010 11726E 010 11713E 010 I1705E 010 11696E 010 l169ZE 010 I1695E 010 11702E 0l0 I1713E 010 11725E 010 i1738E 01

0 11752E 010 11766E 010.11781E 010 I1796E 01

0 IIBIIE Ol0 11827E 01

0 llBq2E 010 I1857E 01

0 I1872E 01

0 I1387E 01

0 11902E 010 11917E 01

0.11931E 010.119_6E 010.11961E 0l0,11976E 0l0.11991E 010.12007E 0l0.12022E 010 12038E 0l0 1205qE 0l

0 12071E 01

0 12088E 010 12107E 0l0 12127E 010 12151E 010 12185E 0l

0 12231E 010 12282E 010 1233_E 0l0 12469E 01

0.00000

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0 17970E-03

0 16918E-030 17258E-030 2926_E-030 282_E-030 26781E-03O 25560E-030 2_7_6E-030 30859E-030 933&OE-030 9_90_E-030 13579E-020 1198qE-0_0 200q0E-020.18611E-020.175_2E-020.16922E-020 16537E-020 16265E-02

0 16068E-020 15940E-020 31387E-020 31100E-020 30304E-020 30580E-02

0 30469E-020 75829E-0Z0 7550_E-020 75301E-020 75171E-020 75089E-020 750_1E-020 75012E-020 75001E-020 75002E-020 75009E-020 75023E-020 750_lE-0Z0 75062E-020 750BSE-020 75110E-020 75135E-020 75160E-020 75187E-020 7521_E-0Z0.752_0E-02

0.75256E-020.75292E-020.75318E-030.753_3E-02

0.75367E-020.75391E-020.75_14E-020.75_38E-020.75_61E-020.75_86E-020.75515E-020.7555_E-02

0.75615E-02

0.75710E-020.60676E-020.30395E-020.30_9E-0Z0.30523E-02

0.00000

SEG

L

2

3

5

57

8

9

I0

ii

1213

It

1516

17

18

19

2O

S-0 30721E 00-0 30_16E 00-0 30112E 00-0 Z9656E 00-0 2897qE 00-0 28Z18E 00-0 27_62E 00-0 26707E 00-0 25952E 00-0 25197E 00-0 2_2E 00-0 Z3588E 00-0 2293_E 00-0 22180E 00-0.21_27E 00-0.20673E 00

-0.19720E 00

-0.19168E 00

-0.18_15E 00-0.17663E 00

HTC0.00000

0.36935E 03

0.39015E 030._10_SE O3

0.42982E 030.44_25E O30._5520E 030.46_62E O30 _7350E 030 _8Z17E O3

0 49078E O30 499_6E 030 50816E 030 51689E 030.52580E 030.53_92E 030.5_2_E O30.55382E 030.56370E 030.57390E 03

XK0 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 SS000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-03

BETA0.000000.000000.0OOOO0.000000.000000.000000.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 000000 000000 00000

FFRAC0 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010.10000E 01

0.10000E 010.10000E 010.10000E 010.10000E 010,10000E 010.10000E 010.10000E 01

RI0 35791E 050 35791E 030 35791E O30 35791E O30 35791E O30 35791E O30 35791E O30 35791E O30 35791E 030 35791E 030 35791E 030 35791E 03

0 35791E 030 35791E 030.35791E 030.35791E 030.35791E 050.35791E 030.3579]E 050.35791E 05

6. Calculated surface characteristics (continued)

Figure 6.4: continued

TSURF DICE

0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

0.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 _ 000000.00000 0.000000.00000 0.000000.00000 0.000000.00000 0.00000

ORIQINAL PAOg I_

OF POOR QUALITY

78

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SEG2122232625262728

3O313233343536373839_0

_2_3

_6

48_9505152535_55_6

58$96061626364656667686970?17273

7576

?9808182838_8586878889909l92939_9576979899

10010110210310_105106107108109ll0III112113

115116117118119

s-0.16911E 0o-0.16159E 00-0.15408E 00-0.1q656E 00-0.13905E 00-0 13155E 00-0 12_0_E 00-0 1165_E 00-0 I0934E 00-o 10154E oo-0 9q037E-0I-0.86537E-01-0.7903_E-01-0.71528E-01-0.64015E-01-0.56491E-01-0._895IE-01-0._1384E-01-0.36069E-01-0.33017E-0!-0.299_SE-01-0.26853E-01-0.23729E-01-0.21363E-01-0.19763E-01-0.18146E-01-0.16506E-01-0.14833E-01-0.13X10E-01-0.11302E-01-0.93693E-02-0 77677E-02-o 6_879E-02-0 53333E-02-0 _3923E-02-0 37712E-02-0 3q932E-02-0 32qlTE-02-n.29800E-02-0.270qSE-02-0.2_173E-02-0.21846E-02-0.20137E-02-0,18393E-02-0.16S29E-02-0.1_501E-02-0,12199E-02-0.91868E-03-0.37066E-03o 37066E-030 9J_G7E-030 12199E-020 14500E-020 16528E-020 18392E-020 20136E-020 21B45E-020.24171E-020.27047E-020.29798E-020.32615E-020.34930E-020.37710E-020,43922E-020.53337E-020.64871E-020.77652E-020.9366_E-020.11299E-010 13107E-010 16830E-0IO 16503E-01o IBlq3E-010 19759E-010 21360E-010 23726E-010 26851E-010.29946E-010.33015E-010.36067E-010.61382E-010.68969E-010,$6489E-010.64013E-010.71526E-010.79032E-010.86535E-010.94035E-01

0.1015qE 000.10906E 000.11654E 000.12604E 000.13155E 000.13905E 000.14656E 000.15_07E 000.16159E 000.16911E 000.17663E 00

HTC0.58452E 030.§9563E 030.60729E 030.61962E 030.63271E 030 6_663E 030 6615_E 030 67753E 030 69q7IE 030 71332E 03o 73360E 03o 7559_E 03o 78085E 030.80885E 030.84079E 030.87784E 030.92188E 030.97611E 030.10231E O40.10552E 060.10916E 060.11327E 040.11790E 040.12172E 060.12451E 040.12752E 040.13082E 040.13452E 060.13848E 060.14194E 040.1_38BE 040.14174E 040.13593E 040.1Z691E 040.11726E 060.10996E 060,10570E 040.10245E 040.98977E 030.95358E 030.9189_E 030.89199E 030.87198E 030.85545E 030.84088E 030,83024E 030.82660E 030.83319E 030.83319E 030.83319E 030.83319E 030.82660E 030.83024E 030.84088E 030.85365E 030.87198E 030.89199E 030.91894E O30.95338E 030.98977E 030.10266E 060.10570E 040.10996E 040.11726E 060.12691E 060.13592E 060.1_176E 060.14388E 040.14193E 060.138_8E 060.1345ZE 040.13082E 040.12752E 040.12451E 060.12173E 060 11790E 060 11327E 060 10916E 060 10552E 040 10231E 0q0 97609E 030 92187E 030.8778qE 030.Sq079E 030.80885E 030.78086E 030.75_96E 030.73360E 050.7_332E 030.69671E 030.67753E 030.661§8E 030.64663E 030.63271E 030.61962E 030.60729E 030.59563E 030.58_5ZE 030.57390E 03

XK0.35000E-030.35000E-030.35000E-030.35000E-030.35000E-03o 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030_35000E-030J35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030,35000E-030.35000E-030.35000E-030.33000E-030.35000Z-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.35000E-030.33000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-030 35000E-03o 35000E-030 35000E-030 35000E-030 35000E-030.35000E-030.35000E-030.35000E-030.35000E-03

BETA0.000000.000000.000000.000000.000000.000000,000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

0.23592E-010.67630E-010.11202E 000.14578E 000.16873E 000.19183E 000.21§25E 000.25102E 000.2B907E 000.32899E 000.38763E 000.66084E O00.68309E 000.52257E 000.55783E 000.58114E oo0.58130E 000.58541E oo0.58976E O00.59439E 000.59922E OO0.60321E 000.60622E 000.60928E 000.61391E 000.61339E 000.61278E 000.61195E 000.61052E 000.61065E 000.611_8E O00.61208E 000.61252E 000,61290E 000.60813E 000.60504E 000.60200E 000.59798E 000.59310E 000.58863E oo0.58403E 000.$7990E 000.58044E O00.35712E 000.52185E OO0,68206E 000.¢q010E 000.38728E 0o0.32898E 000.28961E 000.23168E 000.21581E 000.19281E 000.17014E 000.16760E 000.11446E oo0.70B77E-010,276_2E-01

0 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000,000000.000000.000000.000000o000000.000000.000000.000000.000000.000000.00000

FFRAC0 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 0l0 10000E 01o 10000E 010 10000E 010 10000E 010 10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 0l0.88732E O00.42148E O00.40227E 000.39408E 000.39295E O00.39869E 000.61536E 000.28732E oo0.30615E 000.32831E 000.36170E 000.q0815E 000.47513E O00.57669E 000.78796E 000.78804E 000 57703E oo0 q7567E 000 60883E 000 36252E 000 32923E 000 30516E 0o0.28861E 000.q1691E 000.40052E 000.39510E 000.39660E 000.60533E OO0.62509E 000.89146E 000.10000E 010.10000E 010ol0000E 01O.10000E 010.10000E 010.10000E O10.10000E 010.10000E 010.10000E 010.10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 0l0 10000E 010 10000E 0l0.10000E 010.10000E 010.I0000E 010.10000E 010.I0000E 010.10000E 010.10000E 010.10000E 010.10000E 010.10000E 010.I0000E 010.10000E 01

0.10000E 010,10000E 010.10000E 010,10000E 010.10000E 01

0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E0,35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E 030.35791E 050 35791E O30 35791E 030 35791E 030 35791E 030 35791E 030 35791E 03o 91700E 030 91700E 030 91700E O3o 91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 050,91700E 030.91700E 030.91700E 050.91700E 030.91700E 030.91700E 030.91700E 030.91700E 050.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.9170QE 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030.91700E O30.91700E 030.91700E 030.9£700E 030.91700E 030 91700E 030 91700E 030 91700E 030 91700E 030 91700E O30 91700E 030 91700E 030 91700E 030 91700E 050 91700E O30.91700E O30.91700E 050.91700E 030.91700E 030.91700E 030.91700E 030.91700E 030,35791E 030.35791E 030.35791E 030.35791E O30.35791E 030.35791E 030.35791E 030.35791E O30.35791E 030.35791E 030.35791E 030.35791E 050.35791E 030.35791E 030.35791E 050.35791E 030 35791E 03o 3579IE O30 35791E 030 35791E 030 35791E 030 35791E 03

TSURF03 0 0000003 0 0000003 0 0000003 0 0000003 0 00000O3 o o0ooo03 0 ooooo03 0 0000003 0 00000O3 0 0oooo03 0 0000003 0 0000003 0 00000

0 000000 000000 000000 000000 000000 000000 00000o ooooo

0.26639E O30.26684E 030.26716E 030 26737E 030 26757E 030 26777E 030 26807E 030 26838E 03o 26872E O30 26924E 030.26982E 030.27040E 030.27150E 030.27315E O30.27315E 050.27315E 030.27315E 030.27315E 030.27315E 030.27315E 030,27315E 030.27315E 030.27315E O30 27315E 03o 27315E 030 27315E 03o 27315E 030 27315E 030 Z7315E 030 27315E 030 27315E 030 27315E 05o 27315E O30 27315E O30 27315E 030.27315E 030.27315E 030.27315E 030.27315E 030.27315E 030.27313E 030.27315E 030.27315E 030.271_6E O30.27039E 030.Z6981E 030.26924E 030.26872E O30.26838E 030.26807E 030.Z6778E 030.26758E O30.26738E 050.26718E 030.26687E 030.26643E 03

0.000000.000000.000000.000000.000000.000000.000000.00000

• 0.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.000000.00000

b. Calculated surface characteristics

Figure 6,4: continued

(continued)

ORIGINAL PAGE iS

OF POOR QUALITY

DICE0.000000.000000.000000.000000.000000.000000 000000 000000 000000 000000 000000 ooooo0.000000 000000 000000 000000 000000 000000 0013000 000000 00000

0.Z8542E'-030.47277E'-030.6X_21E'-030.7121QE'-030.80957E'-030.90842E'-030.10594E"020,1Z200E'-020.1388_E--020 16359E--020 18605E'-020 20388E"02o 23969E--020 27681E--02o 26091E--020 25127E--020 2_413E-'020 23660E"02o 2Z883E-O_

.221_5E-02.21577E-02.21159E-0_

0.20815E-020.20520E-020.20277E-020.20175E-020.20275E-020.20302E-020,20302E-020.20272E'-020.20171E-020.20272E.-020.20515E-020.20808E"020 21152E"020 21570E"020 22138E"020 22875E"020 23652E'-020 24403E-'020 25119E"020 26087E"020 27677E"OZo 23770E--020.203_4E-020 18573E-'020 16344E-'020 1388_E-'020 1221_E--020 10622E"020 91076E"030.81371E-.030.71802E-.030.62290E-'030.q8306E-'030.29912E-.03

0 000000 000000 000000 000000 00Q000 000000 000000 000000 000000 000000 000000 00000o oooooo ooooo0.000000.000000.000000.000000.000000.000000.000000.00000

79

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SEG12012i122J23

125126127128

13113223313_135136137138

s0.I8415E 00

0.19167E 000.19920E 000.20673E 0o0.21q27E 000.22180E O00.2293qE O00.2_688E oo0.2_4_2E 000.25197E O00.25951E 000,26706E 000.27q62E 000.28218E O00.2897_E O00.29656E 000.30112E 000.30_16E 000.30721E 00

HTC0.56370E0.55383E0.54_2_E0.53492E0.52580E0.S1689E0.5081qE0._99_4E0._9077E0.q8216E0.473_9E0.46¢60E0.45518E0.q_42_E0_2981E0._1048E0.39015E0.36936E0,31_66E

XK03 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0j_35000E-0303 0'.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-0303 0.35000E-03

BETA0.000000.000000.000000.00000o oooooo ooooo0 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.000000.00000

FFRAC0 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010 10000E 010.10000E 010.10000E 010.10000E 0l0.10000E 0I0.10000E 010.10000E 010.10000E 010.I0000E 010.10000E 010.10000E 010.10000E 010.10000E 01

RZ0 3579iE0 35791E0 35791E0 35791E0 35791Eo 35791E0 35791Eo 35791E0 35791E0 35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E0.35791E

03030303030303030303

b. Calculated surface characteristics (continued)

Figure 6.4: Concluded

0303030,30303030303

TSURF0.000000,000000.000000.000000.000000.000000.000000 000000 000000 00000o oo0ooo oo0ooo oooooo.oooooo.oooooo.oooooo.oo0oo0.000000.00000

DICE0.00O000.000000,000000.000000 000000 000000 000000 000000 000000 000000 000000 000000 000000.000000.000000.000000.00000O.000000.00000

ORIGINAl/PAGE IS

OF POOR QUALITY

8o

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0._

Y O,O

-.2

_(LC_ITY (N'$) 129.00

T_MP(R_TUR[ (C) -[2.60

P_ESSU_ (KPA) 90.76

L_C fG/H--3) 0.50

_P Dl_H (_CRONS) 20.G0

TIME ($EC) 0.00

O

X

Trajectory of particle released from YOMAX

J

Q.Z

0.0

-.2

#ELC31TY (H,'S_ 127.00

TEmPERaTURE (C> -t2.60

_U_IDITY (_) I00.00

_ _3,:_q-3) 0.50

_3P OI_M (MICRONS) 20.$0

TIM[ (S_C) 0.00

o

x

b. Trajectory of particle released from YOMIN

Figure 6.5: Examples of droplet trajectory plots from Example 1.

81

Page 90: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

4').C

_:ELCglTf <N,'S_

TE_F_TU_E (C)

5_EP Ol_H f_ICRON$)

129.00

-12.60

90._5

lO0.OO

0.50

20.00

0.00

YO= 0o00000

S = 0.00000

I

o

x

Trajectory released from YOMAX'I'YOMIN2

0.2

0.0

-°_ .

MELC_ITY (.M/S) 129.00

TEHPER_TUQ[ (C) -12o60

F_!.SSUq_ (KPA) 90.75

HUHIDITY (_) I00.O0

LXZ (_/H..3) O.SO

C_CP 0[_M (MICRONS) 20.GO

TIME (SEC) 0.00

IIt[

j ......

ttJ

0 v

d. Trajectory calculated while searching for the upper impingement limit.

Figure 6.5: continued

82

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ORIGINAL PAGE' IS

OF POOR QUALITY

#EL:;|TY CM/S) ]29.0Q

TEMPER_TUQ[ (C) -12.60

-C_I3]TY (_) 100.00

_P DIeM (MICRONS) 20.GO

":HI (SEC) O,CO

D.2

010 ""

IW= 2

YO= 0,00_50

S - 0,0Z979

II

J ,

I

I

_______-I j

IfJ

e. Trajectory calculated while searching for the upper impingement limit.

Figure 6.5: Concluded

83

Page 92: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

NACA 0012 : EXAMPLE 1

VELOCITY (N/S) 129._6

TENPERATURE (C) -12.60

PRESSURE (KPA) 90.75

HUMIOITY (X) IO0.O0

LWC <G/M=-3) O.SO

OROP OIaM (MICRONS) 20.00

TIME (SZC) bO.O0 ORIGWAL PAGE IS

POOR QUALITy

a. Percent plotted = 100%

NACA 0012 : EXAMPLE 1

VELOCITY (H/S) IZg.q6

IEHPERAIU_E (C) -IE.60

PRESSUnE (KPA) 90.75

HUMIDITY (X) IO0.O0

LWC (G/H=-3) O.SO

DROP O/AN (N|_RONS) 20.00

TIME (SEC) 60.00

b. Percent plotted = 50%

Figure 6.6: Size of the plotted geometry as a function of the percent plotted.

84

Page 93: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

NACA 0012 : EXAMPLE I

VELOCITY (H/S) 129.96

IEHPERATURE (C) -12.60

PRESSURE (KPA) 90.75

HUNIDITY (X) |00.00

L_C (G/H--3) 0,50

DROP O|A_ (NICRON$) 20.00

lIME (SEC) 60.00

c. Percent plotted = 25%

Figure 6.6: Concluded

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a. Iced airfoil geometry

VELOCITY (M/S)

TEMPERATURE (C)PRESSURE (KPA)HUMIOITY (%)

LHC (G/M--3)DROP OIAM (MICROTIME (SEC)

129._6-12.&O

90.75!00.00

0.50N)20.O0

60.00

ORIGINAL PAGE IS

POOR QUALITY

20C -

L150 [-

I6Q _-

1_0 L

=_loo I

I60 F

.o,k

'°i_.35 -°'28 -o=21 -,li_ -o'07 -.;OO 0°;07 0o;!_ 0721 O*:2B O. '_=;

S (M;

d. Edge velocity vs. su_ace location

O.OIC_

0.008

O.OOe

0.00 _

_c 0.002

0.000

o-.00;

-o00'

S (M)

b. Particle release position vs. surfaceimpact distance

ioo m l

i \

"-:2 1

-!8 _

i ......

"2_,'_5 -,28 -.'2; .oT -.io0 0.0; 0.I ° 0,21 O.'2B 3.'35

S (WI

e. Edge temperature vs. surface location

I.O ff I13 _"/ i

°' i ;°'F0.6 :3" ;'"

0.7 . ;3; ,-

t

Lp

0.,, f qe _"

== 0._ 'P2

0.3 e9

0.2 I 6c

o., I e-_-e;.l_ s ' , , , , ,0. O. 0,_ 0 ! 1 0. i_ ._,0 -._'6 -.21 -.1_ ..T? ..tO0 0 .:_. 7 0 • : '_" _..Z: 0._5 _.._5

S (M) S (_')

c. Local collection efficiency vs. surface f. Edge pressure vs. surface location

location

Figure 6.7 Icing parameter plots for the first timestep of Example i.

86

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ORIGINAL PAGE IS

OF POOR QUALITY,VELOCITY (M/S) 129._6TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (%) 100.00LWC (G/M--3) 0.50OROP OlAM (MICRON)20.O0TIME (SEC) 60.00

ni

.:.L

.=_61r

-7 _-

.;_.%_ I ' I ' ' '-.E_ °?El -.'1_' -.'? -.CO O.O7 C..l_" C._ C,._8 C.'35

S (H)

g. Equilibrium surface temperature vs.surface location

ORIGINAE PAGE IS

OF POOR QUALITY

1000 E90C ,

800 r

?00 ]-I

z bO= ,_

_ 50G L

300

IOC :-

j*

J

i , , 1 • .C.'3_ -.2e - .2_ -.]', -.37 .130 C.J; o.J'* 0._1 0.Te "_.3 _.

S (M)

Ice density vs. surface location

1500

;200

]050

900

75G

z600

300

150

h.

j,J

! ,i ' '

5 12_ -.f2; ._:_ -.POT -.OC O.r07 0.I _" O,'ZJ 0.2_ G,13S

S (P)

Convective heat transfercoefficient

vs. surface location

.00050

.000_5

.000_0

.00035

.00030

w. OOO2S

.00020

.00015

.00010

.00005

.oooqo

-.126 -.!21 ..114 ..107 ..100 O.]OF 0._1_ 0.121 O,!ZB 0.135

$ (M)

Equivalent sand-grain roughness

height vs. surface location

I0 kC.9

C'7 F

O.a._-

I0.5 P"

: I

c.2r-

IC,; _

I

C t

-.C;24 - .OG6 0.=C6 G.G2- 0.0_0

S (M)

Freezing fraction vs. surface location

Figure 6.7: Concluded.

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Chapter 7

EXAMPLE CASES

In this section, the capabilities of LEWICE are illustrated through the

presentation of five example cases. These examples include the input data

sets and the printed and plotted output data; however, printed output is

included for example 1 only.

7.1 Example 1: Glaze Icing on a NACA 0012 Airfoil, a -- 0.0 °

In this example, a 2-minute glaze ice accretion will be formed on a NACA

0012 airfoil at an angle of attack of 0.0 degree. The accretion will be formed

in two l-rain timesteps. The icing conditions are shown below:

Velocity

Static Temperature

Static Pressure

LWC

Droplet Diameter

Roughness Height

= 129.46 m/s

= 260.55 K

= 90748.0 Pa

= 0.50 g/m s

= 20.0 microns (monodispersed cloud)

= 0.00035 m

The input file and the interactive input for the first timestep in Example

1 are shown in Figures 7.1a and b, respectively. Plot option 3 was selected

in the interactive input, therefore, the particle trajectories and icing pa-

rameters were plotted. Figures 6.5a-e show the first five particle trajectory

plots from this example case. Figures 6.5a and b show the trajectories of

particles released from YOMAX and YOMIN. As discussed in Chapter 5,

these trajectories are calculated to identify the release point of a particle

that passes above the body and one that passes below the body. These

calculations are performed in subroutine RANGE.

After locating an upper and lower boundary trajectory, the search for

the upper and lower impingement limit is begun by releasing a particle

from a position halfway between the release points of the two trajectories

identified in Figures 6.5a and b. When a particle impinges on the body,

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the particle number (IW), particle release ordinate (Y0), and the surface

impact distance (S) are displayed, as shown in Figure 6.5c. Using the

Newton iteration scheme described in Chapter 4.2.6, the search for the

upper impingement limit is continued, as shown in Figures 6.5d and e.

These calculations are performed in subroutine IMPLIM. When plot option

3 is selected, all of the trajectories will be plotted. Only the first five have

been shown in this example.

After calculating the particle trajectories, the program will prompt the

user to preview the Y0 vs. s data or to continue with the collection emciency

calculation with the following statement.

ENTER 1 TO PREVIEW Y0 VS S DATA

ENTER 0 TO CONTINUE WITH THE COLLECTION EFFICIENCY

CALCULATION (II)

Ifoption 1 isselected and the axes limitsare specifiedas follows:

smin = -0.04 smax = 0.04

y0min = -0.01 yomax = 0.01

the Yo vs. s points calculated in subroutine COLLEC will be plotted as

shown in Figure 7.2. Upon producing the plot, the following statement will

be printed on the screen:

THE CALCULATED SURFACE IMPACT DISTANCES iS) AND

RELEASE POINTS (Y0) ARE AS FOLLOWS

I Y0 S I Y0 S

1 0.00850 0.03378 10 -0.00109 -0.00178

2 0.00765 0.02078 11 -0.00218 -0.00355

3 0.00656 0.01489 12 -0.00327 -0.00555

4 0.00546 0.01090 13 -0.00436 -0.00797

5 0.00437 0.00801 14 -0.00545 -0.01085

6 0.00328 0.00557 15 -0.00654 -0.01484

7 0.00219 0.00357 16 -0.00763 -0.02072

8 0.00110 0.00180 17 -0.00848 -0.03167

9 0.00001 0.00001 18 0.00000 0.00000

HOW MANY TRAJECTORIES ARE TO BE DELETED BEFORE

THE COLLECTION EFFICIENCY CALCULATION? (12)

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At this time, Y0 vs. s points can be removed, if necessary. Non-

physical impact locations can occur when inaccurate flow fields are cal-

culated around the horns of glaze ice accretions. In this example, it is not

necessary to remove any points, so option 0 was selected.

The title of the run, icing condition parameters, ice accretion data, and

parameter plot menu are then printed on the screen as follows:

NACA 0012 : EXAMPLE 1

ICING CONDITION:

STATIC TEMPERATURE (C)

STATIC PRESSURE (PA)

VELOCITY (M/S)

LWC (G/M s)

DROPLET DIAMETER (MICRONS)

ICE ACCRETION DATA

STAGNATION POINT

TRANSITION POINTS (LOWER,UPPER)

ICING LIMITS (LOWER,UPPER)

NUMBER OF POINTS

NUMBER OF SEGMENTS ADDED

AVAILABLE PLOT OPTIONS

0 - NO PLOTS

1 - ICED GEOMETRY

2 - ZVSS

3 - BETA VS S

4 - VE VS S

5 - TE VS S

6 PE VS S

7 - TSURF VS S

8 HTC VS S

9 - XK VS S

10 - ICE DENSITY VS S

11 - FFRAC VS S

ENTER OPTIONS NUMBER (12)

: TIME = 60.000 SEC

260.55

9O748.OO

129.00

0.50

20.00

70

68 71

42 97

139

0

9O

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All of the parameter plots for the first time-step are shown in Figures

6.7a-k. When the option for no plots is selected, the computer will respond

with the following message:

TIME STEP COMPLETE: TIME - 60.0

ICING TIME INPUT HAS BEEN REACHED

PROGRAMS OPTIONS

1 - CONTINUE ICING, USE PREVIOUS FLOW FIELD

2 - CONTINUE ICING, CALCULATE NEW FLOW FIELD

3 - TERMINATE PROGRAM

Since a second 1-min timestep with a new flow field calculation is desired,

option 2 is selected.

The second timestep proceeds in a manner similar to the first. The

plots, computer prompts, and responses are shown in the order of their

occurrence in Figure 7.3. The printed output from the first timestep in

this example is shown in Figures 6.1-6.4. The icing parameter plots for the

second timestep are shown in Figure 7.4a-k. The printed output for the

second timestep is shown in Figure 7.5.

The overall accuracy of LEWICE is checked by comparing calculated

and experimental ice accretion shapes. The experimental ice accretion for

the condition was obtained by Gent (Reference 20), and is compared to the

calculated shape in Figure 7.6.

7.2 Example 2: Glaze Icing on a NACA 0012 Airfoil, a : 4.0 °

This example is identical to Example 1 except that the airfoil is now at a

4.0 angle of attack. The icing time for this condition is also 2-minute and

the accretion is formed in two 1-minute timesteps. The input file is shown

in Figure 7.7. Note that the value of CLT in namelist $24Y is now equal

to 4.0.

Figures 7.8 show the particle trajectories calculated in subroutine

RANGE, where the program searches for a trajectory that passes above

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and below the body. More accurate selections of YOMIN and YOMAX

would have resulted in fewer trajectoriesbeing calculated while the code

searches for the two boundary trajectories.The firstthree trajectoriescal-

culated in subroutine IMPLIM are shown in Figures 7.9. These trajectories

are calculated while the program was searching for the upper surface im-

pingement limit.No additional trajectorieswillbe shown for thisexample,

but alltrajectorieswillbe plotted when plot option 3 is selected. The Y0

vs. s points calculated in subroutine COLLEC are shown in Figure 7.10.

After the plot iscompleted, the following prompts are printed to the screen

to allow the user to remove any incorrect points"

THE CALCULATED SURFACE IMPACT DISTANCES (S) AND

RELEASE POINTS (Y0) ARE AS FOLLOWS

I Y0 S I Y0 S

1 -0.11162 0.01610 10 -0.12296 -0.00836

2 -0.11263 0.01042 11 -0.12425 -0.01156

3 -0.11392 0.00727 12 -0.12554 -0.01528

4 -0.11521 0.00473 13 -0.12683 -0.01979

5 -0.11650 0.00276 14 -0.12812 -0.02534

6 -0.11779 0.00081 15 -0.12942 -0.03270

7 -0.11908 -0.00103 16 -0.13071 -0.04386

8 -0.12037 -0.00315 17 -0.13171 -0.06252

9 -0.12167 -0.00561 18 0.00000 0.00000

HOW MANY TRAJECTORIES ARE TO BE DELETED BEFORE

THE COLLECTION EFFICIENCY CALCULATION? (12)

As in Example 1, option 0 was selected because it was not necessary to

remove any points. The program then entered displays the plot menu to

the screen, and the plots shown in Figures 7.11a-i were obtained. The

results of the first timestep are similar to those obtained in Example 1.

After plot option 0 was selected,the prompts for the program option

were printed, and, as in Example 1, option 2 was selected.The plot option

was not changed from the firsttimestep and the calculationof the potential

flow fieldwas begun. When the program entered subroutine STAG, itwas

found that two "stagnation points_ had been calculated. This is indicated

by the following message and prompt:

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2 STAGNATION POINTS HAVE BEEN CALCULATED. ENTER 1

TO SHOW THE LOCATIONS OF THE CALCULATED STAGNATION

POINTS. ENTER 0 TO DISPLAY OPTIONS.

When this situation occurs, it may be necessary to form a pseudo-surface

over the region where the multiple stagnation points exist. The procedure

to form the pseudo-surface is described in the following section. Appendix C

discusses additional causes for the calculation of multiple stagnation points.

T.2.1 Application of the Pseudo-Surface

In normal operation, select option 1 to display the locations of the stagna-

tion points. The locations of the stagnation points are indicated by X's, as

shown in Figure 7.12. After displaying the plot, the x, y, and s locations

of the stagnation points will be displayed, and the user will be asked either

to select one of the points for use as the stagnation point in the remaining

calculations, or to form the pseudo-surface.

THE FOLLOWING MULTIPLE STAGNATION POINTS HAVE

BEEN CALCULATED

I X Y S

57 - 0.00089 - 0.00336 0.00123

59 - 0.00111 - 0.00309 0.00172

AVAILABLE OPTIONS

0 - CONTINUE CALCULATIONS WITH MANUALLY-SELECTED

STAGNATION POINT

1 - RECOMPUTE FLOW FIELD USING A PSEUDO-SURFACE

In this example, option 1 was selected.

In Figure 7.12, the axes scales were such that it was difficult to identify

the locations of the stagnation points. Therefore, the user will be asked if

the plotting scales should be changed to enlarge the region of interest. In

this example, the axes limits were changed as shown below:

z._ffi= y,_, = 0.02

z_. = y._. = -0.02

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The locations of the stagnation points will then be re-plotted using the new

axes limits, as shown in Figure 7.13.

The circular arc that will be placed over the multiple stagnation points

is defined by specifying two points on the arc and the radius. The two

points on the arc are the locations where the pseudo-surface intersects theactual ice surface. The best results are obtained when the ends of the

pseudo-surface arc intersect on a tangent to the ice surface. Figure 7.13

shows that this may be possible near y values near -0.006 and -0.001. These

values are input by the user as shown below:

ENTER THE Y COORDINATE OF THE DESIRED LOWER

LIMIT OF THE PSEUDO-SURFACE (F10.0)

-.006

ENTER THE Y COORDINATE OF THE DESIRED UPPER

LIMIT OF THE PSEUDO-SURFACE (FI0.0)

-.001

The computer willrespond with the two body coordinates closestto the

desired upper and lower limitsas shown below:

THE POINTS CLOSEST TO THE LOWER LIMIT ARE

X= 0.0019641 Y=-0.0065025 I= 52

X= 0.0012161 Y= -0.0055978 I= 53

THE POINTS CLOSEST TO THE UPPER LIMIT ARE

X= -0.0028274 Y= -0.0010464 I-- 74

X= -0.0029714 Y= -0.0008570 I= 75

The user is then prompted to enter the segment number of the desired upper

and lower limits. In this example, segments 52 and 75 were selected as the

lower and upper limits of the pseudo-surface, respectively. The program

will then request that a radius be input. In this example the radius is 0.03.

The input of these values is shown below.

ENTER THE I VALUE OF THE DESIRED LOWER AND UPPER

LIMITS (213) 52 75

ENTER THE DESIRED RADIUS (F10.0) .03

Because the selectionof an appropriate radius isa manual iteration,there

are no general criteriafor selecting a radius. If an arc with the desired

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radius cannot be formed between the two points specified, the program will

respond by asking for another radius. The iced airfoil with the pseudo-

surface will then be plotted, as shown in Figure 7.14. After the plot is

completed, the following menu is displayed:

THE FOLLOWING OPTIONS ARE NOW AVAILABLE (11)

0 - SPECIFY NEW UPPER AND LOWER LIMITS

1 - SPECIFY A NEW RADIUS

2 PSEUDO-SURFACE SATISFACTORY, CONTINUE

CALCULATIONS

3 PSEUDO-SURFACE UNSATISFACTORY, CONTINUE

CALCULATIONS

WITH THE ACTUAL ICE SURFACE

At this time, new upper and lower limits or a new radius can be selected,

and the above procedure will be repeated. Option 2 will cause the pro-

gram to re-calculate the flow field using the pseudo-surface. Option 3 is

selected when a satifactory pseudo-surface cannot be formed and any errors

in the flow field must be accepted. In this example, the pseudo-surface was

satisfactory, therefore, option 2 was selected.

While it did not occur in this example, multiple stagnation points may

still be calculated after the pseudo-surface has been formed. Unless a

smoother pseudo-surface can be formed, it is usually best to select one

of the points and continue with the calculations. Select the point that is

closest to the stagnation point calculated in the previous timestep. This

point can be identified by the value of surface distance, s. (Recall that s =

0.0 denotes the stagnation point.)

In this example, a single stagnation point was calculated when the

pseudo-surface was placed on the iced surface, and the second timestep

proceeded in a manner similar to the first. It was not necessary to remove

any Y0 vs. s points from the plot shown in Figure 7.15 when the following

prompt was displayed:

HOW MANY TRAJECTORIES ARE TO BE DELETED BEFORE

THE COLLECTION EFFICIENCY CALCULATION? (12)

The plots obtained from the plot menu for the second timestep are

shown in Figures 7.16a-i. The calculated airfoil shape is compared to the

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experimental ice accretion shape, obtained from Reference 20, in Figure

7.17.

7.3 Example 3: Rime Icing on an NACA 0012 Airfoil, a = 0.0 °

In this example, ice will be accreted on an NACA 0012 airfoil at an angle

of attack of 0.0 for 2 min. As in Examples 1 and 2, the accretion will

be formed in two l-rain time steps. The icing conditions, which should

produce a rime ice accretion, are as follows:

Velocity

Static Temperature

Static Pressure

LWC

Droplet Diameter

Roughness Height

= 64.73 m/s-- 260.55 K

- 90748.0 Pa

= 0.50 g/m s

= 20.0 microns (monodispersed cloud)

= 0.00025 m

The input file for this example is shown in Figure 7.18.

The program executes in a manner similar to Example 1. The parameter

plots for the first and second timesteps are shown in Figures 7.19a-i and

7.20a-i, respectively. The predicted ice accretion shape is compared to the

experimental shape (Reference 20) in Figure 7.21.

As discussed in Section 4.3.1, the difference between rime and glaze ice

is determined by the calculated value of the freezing fraction, f (FFRAC in

LEWICE). Figure 7.19k shows that the freezing fraction was equal to 1.0

over the entire surface for the first timestep. This would be indicative of a

solid rime ice accretion. On the second timestep, the freezing fraction was

slightly less than 1.0 near the stagnation point, as shown in Figure 7.20k.

This indicates that the accretion is starting to take on some glaze ice accre-

tion characteristics in that region, and would therefore constitute a mixed

ice accretion. Glaze characteristics become more evident as the freezing

fraction approaches 0.0. Experimentally, these initial glaze characteristics

would probably not be observed until the ice accretion grew larger and the

size of the glaze portion increased.

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7.4 Example 4: Specification of a Droplet Size Distribution

The atmospheric conditions in this example are identical to those in Ex-

ample 1. However, in this example, a droplet size distribution was used to

characterize the icing cloud instead of a single droplet size. The icing time

for this case is 60.0 sec, and the ice will be accreted in a single timestep.

The droplet size distribution was specified to have a normal volume

(mass) distribution with a mean of 20 microns and a = 5, as shown in Figure

7.22. As discussed in Section 4.2.5.1, the droplet size distribution is input

into the code by specifying the mass fraction corresponding to a discrete

droplet diameter. The procedure for quantifying a known distribution for

input into LEWICE is discussed below.

The volume fraction (fraction LWC) corresponding to each droplet size

used to produce Figure 7.22 is shown in Table 7.1. The cumulative volume

fraction (CVF) is calculated for each droplet size, d_, using the equation

CVF_ = CVF(__I) + VI: (29)VVS,

The resulting plot of CVF vs. d is shown in Figure 7.23. For input

into LEWICE, the droplet size range must be divided into a number of

discrete droplet size bins of a constant width. The size of the bin width is

arbitrary, but no more than 10 bins can be input to the code. Using more

bins will increase the accuracy of the calculations but will also increase

computational time. Five bins with a width of 8.0 microns were used in

this example. The droplet diameter corresponding to the middle and the

right-hand side of each bin is shown in Table 7.2.

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Table 7.1 Volume Fraction for a Normal Mass Distribution of

Droplet Size with a Mean of 20mm and a -- 5

d (microns) Volume Fraction

0 0.0000

2 0.0002

4 0.0010

6 0.0032

8 0.0090

10 0.0216

12 0.0444

14 0.0776

16 0.1158

18 0.147"4

20 0.1596

22 0.1474

24 0.1158

26 0.0776

28 0.0444

30 0.0216

32 0.0090

34 0.0032

36 0.0010

38 0.0002

40 0.0000

The cumulative volume fraction at the right-hand side of each bin must

be determined using the data in Table 7.1 and Figure 7.23 using the fol-

lowing equation:

vs, = CVF, - CV F _I (30)

This volume fraction is assigned to the droplet size at the middle of the bin

and assumes a uniform distribution of droplets inside the bin. The values

of V/, for each droplet size bin are shown in Table 7.2. This data is input

into LEWICE using namelist DIST, as shown in Figure 7.24.

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Table 7.2 Volume Fraction for Each Droplet Size Bin Specified in

Example 4

Bin Droplet Diameter Cumulative Volume

Middle Right-Hand Volume Fraction

Endpoint Fraction

1 4 8 0.0082 0.0082

2 12 16 0.2119 0.2037

3 20 24 0.7881 0.5762

4 28 32 0.9918 0.2037

5 36 40 1.0000 0.0082

When a droplet size distribution is input, the execution of the program

is similar to when a single droplet size is specified. The difference is that

the particle trajectory calculations must be performed for each droplet size

specified. Since five discrete droplet sizes were specified in this example,

the impingement limits and Y0 vs. s data were calculated for each of the

droplet sizes. This will require significantly more computational time.

This example will require user interaction when asked to preview the Y0

vs. s data. This question will be asked for each droplet diameter, and the

user will have the opportunity to remove points from each set of y0 vs. s

data. The procedure for removing the points was discussed in Example 1.

Figures 7.25a-o show the plotted output created from the plot menu.

Note that Figures 7.25b-f show the Y0 vs. s curves for each of the droplet

diameters specified. These plots are made from a single selection of plot

option 2. The user will be requested to input the axes limit for each set of

y0 vs. s data. The total local collection efficiency curve (Figure 7.25g) is

calculated by summing the contributions from each of the droplet diame-

ters, as described in Section 4.2.5.1. The local collection efficiency for each

droplet size is not stored by the program.

Recall that in Example 1, an ice accretion was formed for this same icing

condition except that a single droplet diameter of 20 microns was specified.

A comparison of the local collection efficiency from the first timestep of

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Examples 1 and 4 is shown in Figure 7.26. The local collection efficiency

curves are similar near the stagnation point (s = 0.0). However, the region

over which droplets impinge is much greater when a droplet distribution

is specified because of the presence of the larger droplets. This result is

similar to that concluded by previous investigators (Chang, Reference 13).

The increased region of droplet impingement is also noticeable in com-

parisons among the predicted ice accretion shapes. However, because of the

small amount of mass present at the impingement limits, the effect on the

total ice accretion shape is small. These results axe not sufficient for deter-

mining the total effect of using a multidispersed droplet size distribution

to characterize an icing cloud as opposed to a monodispersed distribution.

The effect of wider distributions with similar mass median droplet diam-

eters must be evaluated. The effects must also be determined for various

types of icing conditions and ice accretions.

7.5 Example 5: Thermal Anti-lclng

The formulation of the thermodynamic equations in LEWICE allows the

surface of the body to be a heat source or sink. However, since conduction

through an existing ice layer is not modeled, the equations are valid only

on the first timestep when ice is accreted on the clean airfoil. Also, since

the melting of previously deposited ice from the surface of the body is

not modeled, the equations are not applicable to a de-icing system. They

are applicable, however, to the evaluation of a thermal anti-icing system.

This example demonstrates the capability of LEWICE to determine the

minimum thermal anti-icing heating requirements for maintaining an ice-

free surface for a specified set of icing conditions. A discussion of the

applicability of the thermodynamic model is presented in Appendix A.

The NACA 0012 airfoil evaluated in this example has an electro-thermal

anti-icing heater covering the first 20 percent of the airfoil, as shown in

Figure 7.27. A uniform heat flux of 6000.0 W/m _ was specified over the

entire surface. Lewice is to be applied to determine whether this heat flux

is sufficient to maintain an ice-free surface at the following icing condition:

Angle of attack

Velocity

= 6.0

= 128.41 m/sec

lO0

Page 109: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

Static Temperature

Static Pressure

LWC

Droplet Diameter

Roughness Height

= 265.0 K

= 90748.0 Pa

= 0.50 g/m s= 20.0 microns

= 0.0002 m

The input file is shown in Figure 7.28. The heat flux from the surface (into

the thermodynamic control volume) is input in namelist ICE through the

variable QCOND.

The icing time for this case was arbitrarily specified to be 120.0 sec so

that any ice that did form would be easily visible on the plots. No user

interaction, except the standard responses discussed in Examples 1 and 3,

was required. As shown in Figure 7.29a, the heat input was not sufficient

to maintain an ice-free surface. The ice accretion on the lower surface was

formed as liquid water flowed off the heater and onto the colder airfoil

surface. This result indicates that it is possible for ice to form aft of the

heater but, since the shedding of water droplets from the surface are not

modeled, the amount of ice may be over-predicted. The ice accretion on

the upper surface was formed on the heater itself because the increased

velocity (Figure 7.29d) over the upper surface caused a large decrease in

the local static temperature (Figure 7.29e). It is also interesting to note

the calculated surface temperature and convective heat transfer coefficient

profiles over the surface (Figures 7.29g and h, respectively). The convective

heat transfer was at a maximum on the upper surface which, when com-

bined with the decreased local static temperature, contributed to the ice

growth. The surface temperature profile shows that the temperature was

greater than 0.0 ° C over a large portion of the heater, but was less than 0.0

over a small portion of the upper surface.

These results indicate that the heat flux should be increased in this

region to maintain an ice-free surface. The actual minimum icing require-

ment could be determined by incrementally increasing the heat input and

re-calculating the ice accretion shape. Unfortunately, there was no exper-

imental data to verify these calculations. This example was presented to

demonstrate the capability of the thermal model. It is expected that this

capability be further exercised to evaluate its accuracy.

lOl

Page 110: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

HACA 0012 : EXAMPLE 1

_$24YILIFT= 1IPARA= 1IFIRST= 3ISECND= 3IPVOR= IIHCLT = 0CLT= 0.0/CHORD= 0CCL= 0.0IND = IISOL= 0IPRINT = 0_FLLL = I&END

1.00C0000 0.9899999 0.9800000 0.9700000 0.9500000 0.92500000.9000000 0.8750000 0.8500000 0.8250000 0.8000000 0.77500000.7500000 0.7_50000 0.7000000 0.6750000 0.6500000 0.62500000.6000000 0,5750000 0.5500000 0.5250000 0.5000000 0.47500000.4500000 0.6250000 0.4000000 0.3750000 0.3500000 0.52500000.3000000 0.2750000 0.2500000 0.2250000 0.2000000 0.17500000.1500000 0.1250000 0.1000000 0.0900000 0.0800000 0.07000000.0600000 0.0500000 0.0450000 0.0400000 0.0350000 0.03000000.0?50000 0.0200000 0,0150000 0.0100000 0.0075000 0.00500000.0037500 0.0025000 0.0022500 0.0020000 0.0017500 0.00150000.0012500 0.0010000 0,0008750 0.0007500 0.0006250 0.00050000,0003750 0.0002500 0,0001250 0,0000000 0.0001250 0.00025000.0003750 0.0005000 0.0006250 0.0007500 0.0008750 0.00100000.0012500 0,0015000 0,0017500 0.0020000 0.0022500 0.00250000.0057500 0.0050000 0.0075000 0.0100000 0.0150000 0.02000000.0250000 0.0300000 0,0350000 0.0400000 0.0450000 0.05000000,0600000 0.0700000 0.0800000 0.0900000 0,I000000 0.12500000.1500000 0,1750000 0.2000000 0.2250000 0.2500000 0.27500000.3000000 0.3250000 0.3500000 0.3750000 0.4000000 0.42500000.4500000 0._750000 0.5000000 0.5250000 0.5500000 0.5750000

0.6000000, 0.6250000 0.6500000 0,6750000 0.7000000 0.72500000.7500000 0.7750000 0.8000000 0.8250000 0.8500000 0.87500000.9000000 0.9250000 0.9500000 0.9700000 0.9800000 0.98999991.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0.00000000.0000000 -0.0018740 -0.0036110 -0,0052390 -0.0082510 -0.0117000

-0.0149080 -0.0179530 -0.0208880 -0.0237590 -0.0265150 -0.0292210-0.0318550 -0.0344110 -0.0368870 -0.0392810 -0.0_15850 -0.0437950-0.0459040 -0.0479060 -0.0497930 -0.0515600 -0.0531980 -0.0546980-0.0560510 -0.0572430 -0.0582620 -0.0590900 -0,0597070 -0.0600940-0.0602260 -0.0600760 -0.0596120 -0.0587940 -0.0575700 -0.0558790-0.0536360 -0.0507320 -0.0470040 -0.0452280 -0.0432520 -0.0410380-0.0385350 -0.0356740 -0.0340820 -0.0323620 -0.0304960 -0.0284620-0.0262300 -0.0237260 -0.0207970 -0.0172480 -0.0150780 -0.0123860-0.0106990 -0.0086200 -0.00813&0 -0.0076230 -0.0070750 -0.0064850-0.0058470 -0.0051460 -0.0047660 -0.0043630 -0.0039310 -0.0034620-0.0029_50 -0.0023560 -0.0016320 0.0000000 0.0016320 0.00255600.0029_50 0.0034620 0.0039310 0.0063630 0.0047660 0.0051_600,0058470 0.0064850 0.0070750 0.0076230 0.0081360 0.00862000.0106990 0,0123860 0.0150780 0.0172480 0.0207970 0.02372600.0262300 0.0284620 0.0306960 0.0323620 0.0340820 0.03567_00.0385350 0.0410380 0.0¢32520 0.0652280 0.0670040 0.05073200.0536360 0.0558790 0.0575700 0.05879_0 0.0596120 0.06007600.0602260 0.06009¢0 0.0597070 0.0590900 0.0582620 0.05724300.0560510 0.0546980 0.0531980 0.0515600 0.0_97930 0.04790600.0459040 0.0437950 0.0415850 0.0392810 0.0368870 0.03441100,0318550 0.0292210 0.0265150 0.0237390 0.0208880 0.01795500.0149080 0.0117000 0.0082510 0.0052390 0.0036110 0.00187400.0000000 0.0000000 0.0000000 0.0000000 0.0000000 0,0000000

ETRA¢IGEPS= 0.4999999E-04DSHIFT= 0.20E-02VEPS = 0.9999999E-03LC_B= 0LC_P= 0LEQM = 1LSYM = 0L_OR= IL:<O_ = INBDY = INEQ= 4NPL = 15HSEAR = 50HSI= ITI_STP= 0.9999999E-03££ND&T_AJ2CHORD = 0.30G= 0.0PIT= 0.0PITDOT = 0.0PRATK = 0.0XORC= -4.0XSTOP= 0.50YOLIM = 0.9999999E-04YOMAX: 0.50E-01YOMXH = -0.50E-01YORC= 0.9999996E-01_EHDEDIST

FLtOC= 1.0, 9_0.0DPD= 20.0, 9w0.0CFP= 1.0, 9_0.0_£NO£ICEVIHF= ]29.460LWC= 0.50TAMB= 260.5_98PAMB= 90748.0RH= 100.0DPI'IM= 20.0XF:IHIT= 0.00035EEGTOL= 1.50

a. Input data file

Figure 7.1: Input data for Example 1

102

6036036 036O36036036 03603603603603603603603603b 0 ,36 0 36 0 3603603603603603!136 0 46 0 46 0 q

6046 0 46 0 q6046 0 c+6 0 t+6 06 0 46046 0 _6 0 4

604604604604604

6046046 0 4604I I 4

ORIGINAL PAGE IS

O_ POOR QUALITY

Page 111: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

TIH_ = B.

ENTE_ DESIRED iCING TIME (SEC), (_le.O)

ENTER DESIRED TIME INCREMENT (SEC), (FIB.el6B.

ARE NEW PLOT OPTIONS DESIRED? (Y/N)

AVAILABLE PLOT OPTIONSe - NO PLOTSI - PARAItETER PLOTS ONLY2 - TRAJECTORY PLOTS ONLY3 - PARAHETER AND TRAJECTORY PLOTS

E_TER PLOT OPTION (II)3

THE POTENTIAL FLOW FIELD IS NOW BEING CALCULATED

b. Interactive input

Figure 7.1: Concluded

103

Page 112: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

_:EL::ITY (.M/S_ 129.00

T[MoE_TU_E <C) -12.68

F_SS_E (KP_) g0.75

-C_I_ITY (_) 100o00

TIME (SEC) S.O0

ORIGINAL PAGE IS

OF POOR QUALITY

0.010

0.008

0.006

O.CO_

0._C2

v O. 000

_- -.002

-.00'_

-.006

-.OOg

-. 0 l_

m

l

l

l

q'O

o

o

o

o

o

o

o

o

o

o

o

o

S (M)

Figure 7.2: Yo vs s points calculated in subroutine COLLEC for Example 1

THE CALCULATED SURF_E |HPACT DISTANCES (S) ANDARE _S FOLLOVS

; (0 S

O.Q07gS g.e27152 O.OO?;8 e. QIB443 O,oOSt3 O.Ot3O24 O.OO_tl 0.009645 0.6_49B 9,98694G 0.@0305 0.08370i' B.B@2e3 0.00240e 0.00100 0.B_154g -0.00003 -0.00003

RELEASE POINTS (YO|

l YO S

-0.00106 -O.OO_6O1 -O.@02eB -O.OO25G2 -_.B0311 -O.BB3BS3 -0.B0414 -O.OB7344 -O.OOSI7 -e.oog83S -O.OO619 -0.0132GG -O.BB722 -O.OlOB_7 -B.BBBB2 -0.03702

tO O.OOOOO 0.00000

hO_ _AN_ TRAJE_SOR!ES ARE TO BE DELETED BEFORE*h_l _0_LECTICN EFFICIENCY CALCULATION? (!2_

_ACA 8812 : EXANPLE 1 : TIME- 120.000 SEC

ICING CONDITIONSTAT;C TEHPERATURE (C) 2G0.SSSTATIC PRESSURE (PAD 9B748.B0VELOCITY tH/S) 129.00LVC (G/M_*3) B.SO

DROPLET DIAMETER (MICRONS) 20.00

ICE ACCRETION DATASTAGNAT:GN POINT 74TRANS;TION POINTS (LOWER,UPPER) 72ICING LIMITS (LOWER,UPPER) 43NUMBER OF POINTS 147NUMBER OF SEGMENTS ADDED B

AVAILABLE PLOT OPTIONSB NO PLOTSI ICED GEOMETRY

2 Z VS S3 BETA V$ S4 - VE VS SS - TE vs SG - PE VS S7 TSURF VS SB - HTC VS Sg - XK VS S10 - ICE DENSITY VS SII - FFRAC VS S

ENTER OPTION NUMBER (12)

75103

Figure 7.3: Interactive input and output for the second time step of Example 1.

Page 113: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

ORIGINAL PAGE IS

OF POOR QUALITY

a. Iced airfoil geometry

VELOCITY (M/S) 129,_6TEMPERATURE (C) -12,60PRESSURE (KPA) 90,75HUMIDITY (X) 100,00LNC (G/MN-3) O.SODROP DIAM (MICRON)20.O0TIME (SEC) I2O.OO

2o0FlBO

if_ _2oi ,'"f_IDC [-

2: F_.'35 -.2e -o12: ..T!_ -.'G7 -°IOC 0°'0; C_.:;_ 0.I_I C-_2' 0-135

S (41

d. Edge velocity vs. surface location

C.OIC

C.OO,

C.OOo

C.O0*

_C.O02

-0.000

_-.ooz

-.00.

-.OOe

-.OOg

-.o)_

b.

/./-

o-._3,-._,_-._,.._o6-._oco._o,o._o_.b-_.h_o._oS (M)

Particle release position vs. surface

impact distance

o F-_[-

"2_.!_5 -.'_ -.21 -.:!_ -.'07 -JOO C.I_ : 0.!_ 0,?:I G.:2_ G.'35

S (M)

e. Edge temperature vs. surface location

0.6 F

C.7 L-

_O.S

0"3 F \,

D.2 __0,: F

_'-%O_G 02 OOB 0 03, 0 G2 O.O_O

S (M;

c. Local collection efficiency vs..urf_:elocation

lid

]G7

ICl

98

q5

_2

8q

.o

B3 L

8_'.13_ -.'_E -.'2; -.:I = -.TOt -.[00 OJO; O.I'.* G.121 G.'_' 0.'35

c _m)

f. Edge pressure vs. surface location

Figure 7.4: Icing parameter plots for the second timestep of Example 1.

105

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:F": I-

i-2[-

-9 L

VELOCITY (M/S) 129.1+6TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (X) lO0.OOLWC (G/M,, w3) 0.50DROP DIAM (MICRON) 20.00

TIME (SEC) 120.00

1o00 F

900

800

700 i-

z bOO i

F-- _OO F

300

200

]OO _-

-:-3.}5 -.2g -.2: -.:_ -._; -?00 C.'C/ O.:w ?.2: C.26 C.25

S (M)

Equilibrium surface temperature vs.

surface location

_._5 -.26 -.21 -.I'_ -.07 -.'DO 0.'07 0.]_ 0.'21 0.28 0.35

S (_I!

Ice density vs. surface location

leOO F

Ib20 L

iIw_O F

12bO

IOBO

Iz

720 I

360 L

18C

h,

n_.'35 -.28 -.2_ -.],r -.07 -.00 0.07 0.i,_ 0._i C.26 C.35

S (M)

Convective heat transfer coefficient

vs. surface location

.00050

.000_5

.OO0*C

.0003!

.0003_

.00025

.OO0_O

.00015

.C0010

.0300'

"O00Q_:_5 -.2e -._I -.1_ -._07 -.00 O?Ol c._l_ C.2l C.'ZB G.35

S (M)

i. Equivalent sand-grain roughness

height vs. surface location

;.Of-

O'_ F

O.e.t

C.7 _

O.o L

I:'0.5

: F

o._-G.2 L

!O.] -

!o.o.o,, c

Figure 7.4: Concluded

-.3_- - .OO6 G.3C8 0.02 _ G-O*O

S (M)

k. Freezing fraction vs. surface location

106

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9

10

ii12L$

Z5

1718

192O

21;2

232 (,

2525

2?2829

3O31

32333;

35

3?

3_39_,0

4142(,3

(.4('5(,6(.7

48

495O

U_(TRA;_SFORMED COORDINATE DATA FOR BODY ID =

X(1)

1 00000000 98799970 9799998

0 96999970 9_99997

0 92('99980,8999999

0.87('99990.8('999980.82('9999

0.79999970.7749997

0.75000000.72('99980.69999970.67('99980.64999990.62(.99990.5999998

0.57('99990.5('99997

0.52('99970.5000000

0.47('99980.('(.99997

0.('2499980.39999990.37999990.3('999980.32('99990.2999997

0.27499970.25000000.22('99980.19999990.17499993.14999990.12500000.0999598

0.08999990.07999990.06988('50.05956770.0('947220.0('_0280.03919210.03395770.02870980.02336980.0179198

Y(I)0.0000000

-O.OOIB7qO

-0.0036110-0.0052390-0.0082510-0.0117000

-0.01490B0-0.0179530-0.0208880-0.0237390-0.0265150

-0.0292210-0.0318550-0.0344110-0.0368870-0.0392810-0.0415850-0.0437950-0.0459040-0.0479060-0.0497930-0.0515600

-0.0531980-0.05_6980-0.0560510

-0.0572430-0 05B2620-0 0590900-0 0597070-0 0600940-0 0602260

-0 06O076O-0 0596120-0 05879('0-0 0575700-0.055B790-0.0536360-0.0507320

-0.0470040-0.0452280-0.043252O-0.0('14994-0.0397540-0.0374086-0.0361813-0.034748('-0.0331625

-0.031('767-0.0296603-0.0275407

I, HACA 0012

I X(I)51 0.012252252 0.0063893

53 0.002977654 -0.000699655 -0.002056556 -0.003413557 -0.0053174

58 -0.005347859 -0.005378260 -0.005466561 -0.005582762 -0.005681763 -0.005777364 -0.005892465 -0.005909266 -0.0059506

67 -0.006012268 -0.006089669 -0.006199170 -0.006369171 -0.006473972 -0.006578773 -0.006663274 -0.006747675 -0.0066629

76 -0.006578277 -0.006473178 -0.006368079 -0.006197680 -0.006087881 -0,006010182 -0.005948583 -0.00590708_ -0.005890285 -0.005775086 -0.005679487 -0.005580088 -0.0054638

89 -0.005376490 -0.005346391 -0.005316292 -0.003386493 -0.002027094 -0.0006677

95 0.002986396 0.006394197 0.012253798 0.017918999 0.0233668

100 0.028706¢

: EXAMPLE 1

Y(1)

-0.0250171-0.0218130-0.0197319

-0.0170765-0.0162655-0.0154545-0.0129929-0.0124796-0.0119662-0.0111464-0.0103023

-0.0094149-0.0084782-0.0075095-0.00693('4-0.0063720-0.0057760-0.0051370-0.0044373-0.0036290-0.0030471-0.0024653-0.0012327

0.00000000.00123260.00246520.0030_700.00362870.00_43690.00513660.00577550.00637130.00693370.00750870.00847740.00941390.01030110.01114510.0119654

0.01247880.01299220.01543450 01624320 01705190 01972310 02180710 02501500 0275427,0 02966670.031¢846

ORIGINAL PAGE IS

OF POOR QUALITY

II01

102103

lOqI05106

I0/lO&

1o)L15

Ill112

113114

i15116I17

I18119

120121

122123

12('125126

127128

129130131

132133

134135

136137

138139

140141

I('2143I('4

lq5le,6147

X(1)0 0339538

0 03913650 0442957

0 04946360 059_575

0 06987890 0799999

0 08999990 09999980 1250000

0 14999900 17_9999

0 19999990 22(.9998

0 25000000 27499970 2999997

0 3299999

0 3_999980 37499990 3999999

0.('2_99980.4499997

0._7499980.50000000.52499970.54999970.5749999

0.59999980.6249999

0,64999990.67499980.69999970.72499980.75000000.77499970.79999970.82('99990.8('999980.87499990.8999999

0.92('99980.9('999970.9699997

0,97999980.9899997

1.0000000

Y(I)

o 0331726o 03(.76G20 0362028

0 03743720 0397926

0 04152160 0_32520

0 04522800 09700_00 0507320

0 0536360

0 05587900 05757000 05879_0

0.05961200.0600760

0.06022600.0600940

0.05970700.05909000.0552620

0.0572430

0.05605100.05469800.05319800.0515600

0.04979300.0('790600.0('59040

0.04379500.0415850

0.03928100.03688700.03441100.0318550

0.02922100.02651500.02373900.02088800.01795300.01990800.0117000

0.00825100.00525900.0036110

0.00187('00.0000000

DOUGLAS

COrlBIHED FLO{.i

ALPHA = 0.000000

CL = 0.000002

BODY IO = i

T 7

I 0.99500,'?.52 0 .9850022

3 0.975001.3(' 0. 96000('5

5 0.9_750(.qs 0.91250257 0.8875015•_ 0.8625011

9 0.B375007!O 0 .8125005'.1 0.7875003

12 0.752500813 0 73}5007

I(. 3.712500515 0 .637500_16 0,562500417 0 657900_15 0.6125008

19 0.587500/20 0.56."5006

21 0.537500522 0. 512500921 0.qB750092(' 0.462500825 0.4375007

26 0.412500727 0. 387500628 0. 362500529 0.337500330 0. 312('999

31 0.287('99('32 0.262q990

33 0.23749833t+ 0.2124971

35 0. 187495636 0. 16;.t. 73137 0.137489338 O. 112483139 0.0949959(.0 0.08q999941 0.0749(.38

A[FC_AFT COHPAHY TWO-DIHENSIONAL POTENTIAL

HAC_ 0012 : EXAMPLE I

ALPHA O = 0.000013

CHORD : 1.000000

HACA 0012 : EXAMPLE 1

Y

-0,0009536-0.0027573-0.00('4365-0,0067780-0.0100112-0.013328('-0.016_(.70-0.019_323-3.0223233-0.0251359-0.0278?68-0 0305473-0 0331427

-0 0356590-9 03B0946

-00qO('(.q4-0 0('27021-0 044862('

-0 0469188-0 0('88641

-0 0506920-0 0523956-0 0539657-0 0553936-0 0366678-0.0577752-0.0587010-0.0594260-o.o5993o8-0.0601935-0.0601882-0.0598856-0.0592503-0.0582363-0.0567876-00548323-0.0522749

-0.0489800-0.0461379

-0.0442400-0,0423663

S0.002_7150.00740850.01233520.019709;0.03075280.04300580.0552('620.06747840.07970510.09192750.1041459

0.11636050.1285714

0.1('0778('0.15298150.16518060.17737560.IB95665

0.20175310.21393560.22611370.23828740.250_5690.262622_0.27478380.286941_0.29909540 31124620 32339_40 33554100 34768690 35983370 3719836

0 38414000.39630690.40849100.42070220.43295640.4915639

0.44650720._514770

FLOW PROGRAM

NO. OF BODIES

TOTAL ELEMENTS

NO. OF ELEMEHTS

VT-0.8268182-0.8886436-0.9189040-0.9450629-0.9680377-0.9839131-0.9951214-1.0043230-1.0127668-1.0207739-1.0284805-1.0360298-1.0433102-1.0503035-1.0572052-1.0640011-1.0706520-1.0772190-1.0836945-1.0900660-1.0963779

-1,1027031-1.1089926-1.1153297-1.1216908-1.1280737-1.1345110-1.1408377-1.1470585-1.1531639-1.1590567-1.1697253-1.1701040-I 1749191-I 1788921

-I 1814556-1 1815958-1 1766272-1 1659_98-1 1386347

-1 128655_

1

146

I96

CP

0.31637160.21031250.15561540.10685620 06290310 03191500 0097334

-0 0086641

-0 025695_-0 0419789-0 0577717-0 0733576-0 0884953-0 1031370-0 1176825I 0 1320982-0.1462955-O.16O4OO4-0.1743937-0.1882429-0.2020_26-0.2159538-0.2298641-0.2_39604-0.2581892-0.2725496-0.2871151-0.3015099-0.3157_25-0.3297863-0.3434114

-0.3565845-0.3691('25-0.3804390-0.3897858m0.3958368--0.3961678"0.38_4509--0.3594389--0.296488B--0,2738628

JI

23

456789

l0]112131(.15161718192O2122232('252627282930313233343536373B39('0ql

SIGtIA-0.013141

-0.013129-0.012670-0.012000-0.011207-0.010559-O.OlOlqO-0.009907-0.009760

-0,009630-0.009516

-0.00938('-O.O09213-0.009036

-0,008853-0.008626-0.008386-0.008112-0.007813-0.007('77-0.007127-0.006738-0.0O6311-0.005851

-0,005326-0.004755-0.00('099-0.003351-0.002524-0.001583-0.000526

0.0006710.0020470.0036660 0055580 0078530 0106530 0142430 017('080 0199400 014238

VN0.000004

0.00000('0.00000('

O.0O00O4

O.OO00040.00000(.0.0000030.000002

0.0000010.0000010.000001

0.0000010.000001

0.0000010.000001

0.000001O.O000010.000001

0.0000010.0000010.000001

0.0000010.000000

0.000000o.080o000.O0OOOO0.0000000.0000000.000000

0.0000000.000000

-0,000000-0.0000000.000000

-0 000002-0 000002-0 00000('-0 0OOO04

-0 O0000q-0 000003

-0 000003

Figure 7.5: Printed output for the second time step of Example 1

107

Page 116: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

88

89

9O9192

0394

9596

9798

99leoIOl

102103

10't

105106107

108109

110Ill

If2113ll4

i15

I16I17If8

119120

121122

123

DOUGLAS A _.CRiFT

CCMBZrtE_ FLC_

ALFtlA : 0.000000

CL = 0.000002

BODY ID = I

I X42 0.06_7761q3 0.05_5632

_5 0.0417_68_6 0.0365461_7 0.031330548 0.026033749 0.020632_50 0.015066_

51 0.009292_52 0.00_670253 0.00113905q -0.001377955 -_.07_735056 -0.00_589257 -0 005332758 -0 005363059 -0 005_181

60 -0 00551q661 -0 0056339

6? -0 005729563 -0.00583q86q -0.005900865 -0.005_37_66 -0.0059797

67 -0.0_0_8968 -0.0061q07

69 -0,006_8qI:0 -0.006q21571 -0.006526372 -0.006621573 -0.0067059

7q -0.006705275 -0.0066205

76 -0.006525877 -0.006&Z0678 -0.006_82879 -0.006139080 -0.0060_7081 -0.005977682 -0.005925383 -0.005_q_6

8q -0.005832685 -0.005727286 -0,005631q87 -0.0055219

-0.005qi58-0.0053613

-0.0053312-0.00q5729-0 0027067-0 0013_72

0 0011593

0 00q67650 009295q0 0150667

0 0206308

0 026030_0 03132690.0365_1_0.0q171050.0q687750.05q553_0.06q76810 0749q080 08q99990 09q99590 1124831

0 137#8930 162_931

0 187_9560.212_9710.237_9830.262_9900.287_99q0.31249990.33750030.36250050.3875006

0.q1250070._3750070.4623008

COrIpA?(Y

HACA 0012 : E:,:A_PLE

ALPHA 0 =

CHORD =

NACA 0012 : EXAMPLE

-0.0q06267-0,0386106

-0.0368035-0.035_850-0.0339678-0.0323297-0.0305865-0.0286313-0.0263229-0.0234670-0.02079_2-0.01840_2-0,0166708

-0.0150600-0.01q3968-0.0127363

-0.0122229-0.0115558-0.01072_3

-0.0098588-0.0089465-0.0079938-0.0072219-0.0066530-0.0060738-0.0054563-0.0047866

-0.0040331-0.0033380-0.0027562-0.0018490-0.000616_

0.00061630.0018489

0,00275610.00333790.00_03280.00_78620.005_5580.00607320.00663230.0072212

0.00799300.0089456

0.00985770.01072310.01155_8

0.01222210.01273550.01_388_0.01583880.0166q730.01838750 02078750 023_6310 0263228

0 02863560 03059370 032338_0 033980_

0 03550360.03682880.0386_570.0_065710.0_237820,0_2_000.0_613790.0_898000.05227_90.05483230.05678760.05823630.05925030.05988560.06018820,06019330.05993080.059_2600.05870100.05777520.03666780.0353936

THO-DI_EHSIOH_L POTEHTIkL

i

0.000013

1.000000

I

FLON PROGR_{1

S0.456q88q0.4615475

0,46537950.q6797110.q7058920.q732_500.6759541

0.47874q70.4816726

O.q8q80310._8739730.48946990._9095570.49172360._9288010._9377750.49402730.49_352_0.69_75960._95183_0._9362900.q9609_60.696_712

0._967_790._97030_0.49733220.69766060,_9803320.q98377q0.69866_60.q9910830.q9970850.50030880.50090900.30135270.50163980.50198_10.50235670.30268310.50298690.50326960.5035_610.50392270.50_38830.50_83380.30525750.50566490.30599010.50623990.50713750.50829_0.50906280.S105q6q

0.51261630.51520970.51833990,52126750.52q05820.52676730.529_2_20.5320q130.33q63290.538_6500,5_352_70.5_853700.35350730.558_5030.56705800.37931220.591523_0.60370760.61587_50.62803080.6_018080.65232750.66_735

0.67662000.68876820,70091900.71307300.7252306

0.7373920

HO. OF BODIES

TOTAL ELEHENTS

HO. OF ELEHERTS

VT

-I.166576_-I.1738958-1.1783762

-1.181_q80-I.1633625

-I.lq959q3-I.152104q

-1.1499968-1.1401501

-1.0972996-1.0662109-0.9627361-0.9737q62-i. I0183_3

-1.2881260-0.8853139-0.710_751-0.627910q-0.5720q86-0.5080939-0._1_389-0._16525_-0.3197q75-0.3052155-0.2738528-0.2_70832-0.216q860-0.2118799-0 17q696_-0 1783613-0 09359q3

-0 06071500 06029200 09q_7910 17925080 17503110.2121_6_0.2167311

0,2_7q2530.27603070.30561210.32005_70._1699080.6619_790.308887_0.5723_7_0.62878070.71305770.88910311.29076291.09589960.96887770.958_5631.0659027

1.09725671.16003751.15017601.1523075I.I_926821.16315081.18176861.17917731.17607_01.1687_981.12822821.13737_91.1656160

1.176_8511.18153191.181q2031.1788692

1.17_90391.17009331.16_71671.13906901.1531582

1 1_703371 I_083391 13_50811 12807081 12168881 1133278

1

146

I_6

CP-0.3608999-0.3780308-0.3885698

-0.3958187-0.353_I17

-0.3215666-0.3273439-0.322_916-0.2999_20-0.2040663

-0.1325_50.07313930.051818_

-0.21q0379-0.65926840.216219_0.49522510.60572860.672760q0.7_184060.80513180.82650670.89776160.9068_350.92390530.93896990.95313390.95510690.969_8120.96818730.9912_010.9963138

0.99636q90.9910737

0.96786920.96936_20.95_99_00.933O2770.93878070.92380710.90660130.89756510.82611870.80_68210.7_I03370.67218950.60463_90._9156880.209_958

-0.6660681-0.200995_

0.06127610.0813615

-0.1361_85-0.2039719-0.2996855-0.32190q6-0.3278122-0.3208170-0.3529196-0.3963292-0.390_391-0.3831501-0.365975_-0.2728987-0.2936211-0.3386607-0,38_1162-0.3960171-0.3957539-0.389732_-0.3803988-0.3691187-0.33656_5-0.3_339_3-0.3297729-0.3137320-0.3013013-0.287108q-0.2725q30-0.258185_-0.2_39356

Figure 7.5: continued

d

434q_+5_6q748_95051525354555657585960616263646566676869707I72737q7576777879808182838_8586878889909192939q9596979899

lO0101102103lOq105106107108109110111112113

115116117118119120121122123

SIGMA

0.0115_20.019G2_

0.0105030.0235590.026692

0.0271_60.0272q80.03124q0 03_985

0 0_29640 0q3626

0 0_90180 02358_0 009558

0 0q33060 1260q3

0 1289690 1282950 123520

0 12q8370 127661

0 1256300 1316_5

0 1364770 1352100 13_6700 133_900 12_528

0 1198060 114872

0 1180390 I1603q0 1162090 I181_30 114737

0 1197280 12_920 133_580.13q6600.1352130.136_30.1316150.125575

0.1275890.12q7220,123q680.1283030.128798

0.1257870.0q1929

0.0097220.0237460.0501_20,0_37910.04310_0.0351320.0313950.0273000.0272250.0269010.0237530.0187360.0195680.011189

0.0138230.0199_20.0174050.01_238

0.0106_90.0078_80.00555_0,0036620.00204_0.000669

-0.000528-0.00158_-0.002526-0.003353-0.00_101-0.006757-0.005328-0.005852

ORIGINAL PA_E IS

OF POOR QUALITy

VH

-0.000002-O,000002-0,000002

-0.000001-O.000002

-O,OOO002-0.000001

-O,OO0O01-0.000001

-0.000000-0.0000000,000000

0.0000020.000003

0.000004-O.OOO032-0.000030-0 000026-0 000018

-0 000024-0 000025-0 OOOO24

-0 000032-0 000023-0 OOO023-0 000022-0 000015-0 000002

-0.000010-0.000008

-0.000025-0.000027-0.000026-0.000027-0 000007-0 OOOO08-0 000003-0 000015

-0 000021

-0 000023-0 000026-0.000026

-0.000019-0.000023-0.000021-0.000018-0.000026-0.000025

-O.O0002qO.O0000qO.OO0O01

-O.O00001-O.O00001

-O.OOOO02-O.OO0OO2

-0.000002-0.000003

-0.000003-0.000003-0.000003-0.000003-0.00000_-0.00000_-0.000003-0.00000_-0.000003-0.00000_-0.000003-0.000002-0.000002-O.O0000Z

0.0000000.0000000.0000000.0000000.000000

0.0000000.0000000.0000000.0000000.0000000.000000

108

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_OUGLAS ATPCRAFT COMPANY T_O-DIHENSIONAL POTENTIAL

CO,DINED fl.O_ NACA 0012 ; EXAMPLE I

A!,PtlA = 0.000000 ALPHA O = 0.000013

CL : 0.000002 CHORD = 1.000000

BODY ID = I NACA 0012 : EXAMPLE 1

I X Y S

i2q 0.48?5009 0.0539657 0.7495575125 0.5125009 0.0523956 0.7617270

126 0.5375005 0.0506920 0.7739007I27 0.5625006 0.0488641 0.7860789

(28 0.5875007 0.0469188 0.7982613129 0.6125008 0.0648624 0.8104479130 0.6375008 0.0427021 0.822638813I 0.6625004 0.0404444 0.8348338132 0.6875005 0.0380946 0.8470329

133 0.7125006 0.0356590 0.8592360134 0.7375007 0.0331427 0.8714_30135 0.762500B 0.0305473 0.8836539136 0.7875003 0.0278768 0.8958685137 0.8125005 0.0251359 0.9080870138 0.8375007 0.0223233 0.9203093139 0.8625011 0.0194323 0.9325360140 0.8875018 0.0164470 0.9447682141 0.9125025 0.0133284 0.9570085142 0.9375044 0.0100112 0.9692615143 0.9500045 0.0067780 0.9803048144 0.9750013 0.0044365 0.9876790145 0.9850022 0.0027573 0.9926056

146 0.9950025 0.0009536 0.9975426

INTEGRATED VALUES

CY = 0.00003 CX = -0.00106

CL = 0.00003 CD = -0.00106

PARABOLIC INTEGRATION

IHTEGRATED VALUES

CY _ 0.00002 CX = -0.00030

CL = 0.00002 CD = -0.00030

TOTAL CM = 0.00000

CM : 0.00000

CM = 0.00000

FLOW PROGRAH

NO. OF BODIES 1

TOTAL ELEMENTS I_6

NO. OF ELEHEHTS 146

VT CP1.1089916 -0.22986221.1027021 -0.21595191.0963764 -0.20204071.0900640 -0.1882391

0836935 -0,1743908I 0772171 -0.1603966i 0706501 -0.1462908I 0640001 -0.1320953i 0572042 -0 11768051 0503025 -0 10313511 0433102 -0 0884953I 0360289 -0 07335571 0284805 -0 0577717

• 0207729 -0 0419769.0127659 -0 0256939

• 0043221 -0.0086622• 9951208 0.0097346

0.9839124 0.03191640.9680369 0.06290460.9450626 0.10685680.9189037 0.15561600.8886423 0.21031500.8268158 0.3163756

TOTAL CH = 0.00000 (PARABOLIC)

ORIGINAL PAGE IS

OF POOR QUALITY

J124

125126127

125129

130131

132133

134135

136137

138139

140141142143

144145

146

SIGHA-0.006312

-0.006739-0.007128

-0.007478-0.007814-0.008112-0.008386-0.008627

-0.008853-0.009036

-0.009214-0 009384

-0 009517-0 009631-0 0O9760-0 009907-0 010141-0 010560-0 011207-0 012000-0 012670-0 013129

-0 013141

VN

0.0000000.000001

0.0000010.0000010.000001

0.0000010 000001

0 0000010 000001

0 0000010 000001

0 0000010.0000010.000001

0.0000010.000001

0.0000010.0000010.000004

0.0000050.000004

0,0000050.000004

T'IE PARTICLES

WHICH IS OBTAINED AT TIIE

GEOHETRY CHARACTERISTICS:

LEADItIG EDGE (X,Y)T_,ILIt(G EDGE IX,Y}THICH,_ESS

CHOPDA;4GLE CF ATTACK

UI'FER BCUt{DAPYLO'_EB BOUNDARY

PARTICLE TRAJECTCRY DATA:

ARE RELEASED FROM Z = -1.26000E 00

I LOOP OF 50 LOOPS

-4.0243E-03

3.0200E-014.0136E-02

3.0000E-010.0000

2.2075E-02-2.2075E-02

2.0715E-070.0000

THE PARTICLES ARE RELEASED I_I EQUILIBRIUM HIT}I THE AIR

PARTICLE IHITIAL I?IITIAL PARTICLE PITCH PIT GRAVT ERRGR_IA:_ER VX VY AOA ANGLE DOT CONST CRITERIA(HICROHS} (M/S} (M/S} (DEGREES} (DEGREES) (DEG/SEC) (M/SW_2)

20.00 0.00 0.00 0.00 0.00 0.00 0.00 5.00E-05

Tile PARTICLES OF SIZE 20.00CONTAIN 1.0000 OF TIIE TOTAL HASS

X0 Y0 XP YP

-1.2599993 0.0090961 OUT OF RANGE 0.0831582 0.0226937-1.2599993 -0.0090835 OUT OF RMIGE 0.0828083 -0.0226548

YOHAX = 9.09_1E-03 YOMIN = -9.0835E-03

DT4.6785E-055.2456E-05

-1.2599993 0.0000063 NIT BODY AT -0.00_0239 0.0000050 0.0000050 8.1206E-06-1.2599993 0.0045512 NIT BODY AT -0.0009029 0.0054289 0.0082736 2.8464E-06-1.2599993 0.0068236 HIT BODY AT 0.0061579 0.0088386 0.0162043 9.2295E-06-I.2599993 0.0079599 NIT BODY AT 0.0166598 0.0117465 0.0271505 6.7323E-06-1.2599993 0.0085280 OUT OF RANGE 0.0813009 0.0221908 4.7782E-05-1.2599993 0.0082439 OUT OF RAtIGE 0.0829488 0.0222186 4.7512E-05-1.2599993 0.0081019 OUT OF RANGE 0.0871353 0.0226163 6.1404E-05-1.2599993 0.0080309 OUT OF RANGE 0.0854309 0.0225082 4.4515E-05-1.2599993 -0.0005618 HIT BODY AT *0.0039709 -0.0006448 -0.0007154 6.9591E-06-1.2599993 -0.0048227 HIT BODY AT -0.0003887 -0.0057987 -0.0089134 3.1107E-06-1.2599993 -0.0069531 HIT BODY AT 0.0069689 -0.0091094 -0.0170804 1.i02BE-05-1.2599993 -0.0080183 HIT BODY AT 0.0263552 -0.0135138 -0.0370157 9.9582E-06-I.2599993 -0.0085509 OUT OF RANGE 0.0868925 -0.0228065 4.9236E-05

-1.2599993 -0.0082846 OUT OF RANGE 0.0823606 -0.0221761 4.0522E-05-1.2599993 -0.0081514 OUT OF RANGE 0.0851743 -0.0224173 5.1358E-05-1.2599993 -0.0080849 OUT OF RANGE 0.0836582 -0.0222142 4.8017E-05

0.01844340.0130234

UPPER SURFACE LIIIIT LOWER SURFACE LIMIT

YOU SU Y0L SL0.7960E-02 0.2715E-01 -0.8018E-02 -0.3702E-01

-1.2599993 0.0071610 flIT BODY AT 0.0082593 0.0095326-1.2599993 0.0061338 HIT BODY AT 0.0032192 0.0076855

9.5929E-067.8691E-06

HSTP101

97

4168

65Bo95

111116119

455658

9187

108iii

92

7168

Figure 7.5: continued

109

Page 118: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

-i.2599993 0.0051065 HIT BODY AT-1.2599993 0.0040795 fliT BODY AT

-1.25q9993 0.0030523 HIT BODY AT-!.2599993 0.0020251 ?lIT BODY AT-1.2599993 0.0009980 HIT BODY AT

-L.2579993 -0.0000292 HIT BODY AT-1.2599993 -0.0010564 fliT BODY AT

-1.2599993 -0.0020835 HIT BODY AT-1.2599973 -0.0031107 HIT _ODY AT-1.2599793 -0.0041379 HIT BODY AT

-|.2599993 -0.0051650 flit BODY AT-L.2599993 -0.0061922 HIT BODY AT

-1.2599993 -0.0072194 HIT BODY AT

0 0002541-0 0018151

-0 0036111-0 0037484-0 0038598

-0 0040216-0 0036480-0 0087397-0 0036065-0 0016187

0 00041490 003435B0.00865_1

0.0061759

0.00481640.0035133

0.00233660.0011532

-0.0000330-0.0012178-0.0024063-0.0035786-0.0048994-0.0062647-0.0077756-0.0096553

0 00963_20 0069433

0 00378470 00249180 0015363

-0 0000332-0 0016015

-0 0025623-0 0038509-0 0073419-0 0098281-0 0132625

-0 0188647

4.0084E-062._937E-066.9544E-06

1.0324E-05_.0499E-068.1260E-06

8.0255E-066.3720E-06

4.9189E-062.7035E-064.3314E-069.5905E-067.5941E-06

'(0 VS S _AT,'. FCR DROPLET DIAIIETER _17 POINTS I!AVE BEEN CALCULATED

i

L23

5

? 08 09 -0

10 -011 -0

12 -013 -0i', -015 -0

16 -017 -0

S YO

0 027150 3.0079600.0184_3 0 007161

0 013023 0.006134049538 0005107

0 0069G3 0,004079003785 0 003052002492 0.002025

001536 0.0009980000_3 -0.00002900L602 -0.001056

002562 -0.002084303851 -0.0051110073_2 -0.004138009828 -0.005165013263 -0.006192018_65 -0.007219

037016 -0.0080LB

20.00000 MICRONS

CALCULATED

S_G SI -0.311805

2 -0.3076263 -0304559

4 -0.2999815 -02931416 -0.2855577 -0.2779858 -0.270_22

9 -0.252865

11 -] 2_7761IZ -0.2%0213

l_ -0.232S67i_ -0.225122

15 -0.21756016 -0.210040

17 -0.20250212 -,2+194966

19 -0.18745320 -0.17990121 -0.172371

22 -0.1648_423 -0.157318

24 -0.14979_25 -0.142272

26 -0.13475027 -0.12723028 -0.I19710

29 -0.11219030 -0.10466931 -0.0971q632 -0.089620

33 -0.0B208934 -0.074550

35 -0.06700036 -0.05943237 -0.051B3838 -0.04421839 -0.03684940 -0.03577041 -0.03271642 -0.02960743 -0.02642544 -0.024004

45 -0.022348

46 -0,02068047 -0.01900_08 -0.017286

49 -0.01548650 -0.013567

LOCAL COLLECTION EFF_CIEHCY FOR DROPLET DIAMETER =

BETA SEG S

0 0008000 000000

0 0000000 000000

0 0000000 0000000 0000000 0000000 000000

0 0000000 0000000.000000

0.0000000.000000

0.0000000.000000

0.0000000.0000000.0000000.000000

0.0000000.0000000.080000

0.0000000.0800000.0000000.0000000.0000000.0800000.0000000.000000O.0000O00.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0000000.0190780.0624260.0954000.117956

0.1406850.163511

0.1869250.2114370.237579

20.00000 MICRONS

BETA

-- 51 -0.011512 0.31260052 -0.009782 0.334206

53 -0.008418 0.33286654 -0,007550 0.33201555 -0.006894 0.37361856 -0.005735 0.40860357 -0.001q76 0,q_668558 -0.0038',2 0.67219759 -0.003704 0.702001

60 -0.003688 0.7t+890561 -0.003210 0.8090_962 -0.002921 0.871553

63 -0.002613 0.93836264 -0.002321 0.85002465 -0.0G2153 0.83777766 -0.002940 0.82947967 -0.001904 0.819519

68 -0.001772 0.80990269 -0.001598 0+857995

70 -0,001381 0.83318471 -0.001112 0._0257472 -0.000728 0.758828

73 -0.000254 0.70_71674 0.000254 0.71287q75 0.000729 0.76748176 0.001113 0.81165377 0.001381 0.842557

7B 0.001599 0.B0246779 0.001773 0.81502680 0.001904 0.62453081 0.002040 0.83436382 0.002153 0.84255083 0.002321 0.85_658a4 0.002612 0.924965

85 0.002921 0.85738486 0.003210 0.79416087 0.003487 0.73354088 0.003702 0.68637089 0.003840 0.50082590 0.004483 0.47375291 0,005731 0.42041592 0.006902 0.37200593 0.007548 0.3¢075794 0.00840B 0.33722695 0.009775 0.34323396 0.011507 0.29858297 0.013561 0.24213298 0.015481 0.20992699 0.017280 0.179721

100 0.018999 0.150880

HICA 0012 : EZAHPLE 1

ICIHG CO:(DITIO_(:

%TATIC TE;1PER_TURE (C)STATIC P_ESSURE (PAl

VELOCITY (M/S)LWC (G,'_'_3)DROPLET DIAMETER (MICRONS)

: TIME= 120.000 SEC

260,5590748.00

129.000.50

20.00

ICE ACCBETION DATA;

STAGNATION POINTTRANSITION POINTS (LO_ER,UPPER)

ICING LIMITS (LOWER,UPPER)PIUM_ER OF POII(_S

NU_BER OF SEGME?(TS ADDED

7472 7543 103147

8

Figure 7.5: continued

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10110210310410510610710B109110

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S BETA0.020674 0.122772

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0 051835 0 0000000 059429 0 000000

0 066997 0 8000000 074547 0 000000

8 082086 0 0000000 089618 0 0000000 0971_3 0 0000000 104666 0 000000

0 1121B7 0 0000000 119707 0 000000

0 127227 0 0300000 134748 0 0000000 42269 0 000000

0 149791 0 000000

0 157315 0 0000000 164841 0.0000000 172369 0.000000

0 179898 0 0000000 187430 0.0000000 94964 0.0000000 202500 0.000000

0 210038 0.0000000 217578 0.0000000 225120 0.0000000 232664 0.000000

0.240210 0.0000000.247759 0.0000000.255309 0.0000000.262863 0.000000

0.270419 0.0000000.277982 0.000000

0.285554 0.0000000.293138 0.0000000.299979 0.0000000.304556 0.000000

0.307624 0.0000000.311802 0.000000

Page 119: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

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Figure 7.5: continued

111

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ORIGINAL PAGE IS

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Page 120: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

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ORIGINAL PA_ _

OF. POOR QUALITY

Page 121: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

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ORIG/NAL PAGE IS

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Figure 7.5: continued

113

Page 122: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

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114

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ORIGtNAL PAGE IS

OF POOR QUALITY

Page 123: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

SEG S QCOtlD MDOTC MDOTRI MDOTE MDOTTI M_OTT120 0.129|1E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000121 0.13661E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000I22 O.l_12E O0 O.OOO00 0.00000 0.00000 0.00000 0.00000 O.O00001_3 0.15163E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.0000012_ 0.1591_E O0 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000125 0.16666[ 00 0.00000 0,00000 0.00000 0.00000 0.00000 O.O0000]26 0.]7_]8E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000127 0.18170E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000128 0.18922E 00 0,00000 0.00000 0.00000 0.00000 0.00000 0.00000129 0,1967_E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00O00130 0.20q27E O0 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000131 0.21180E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000132 0.21933E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

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I36 0.2q9_9E 00 0.00000 0.00000 0.0O000 0.00000 0.00000 0.00000]37 0.2570_E 00 0.00000 0.00000 0,00000 0.00O00 0.00000 0.00000

]38 0.26q58E 00 0.00000 0.00000 0.O0000 0.0000O 0.00000 0.00000139 0.27213E O0 0.00000 0.00000 0.00000 0.00000 0.00000 0.000001_0 0.27969E O0 0.00000 0.00000 0.00000 0.00000 0.00000 0.000001_| 0.2872qE 00 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000]_2 0.29_81E 00 0,00000 0.00000 0.00000 0.00000 0.00000 0.000001_3 0.30163E 00 0.00000 0.00000 0.00000 0.00000 0.00000 0,00000I_ 0.30613E 00 0,00000 0.00000 0.00000 0.00000 0.00000 0.00000

lq5 0.30923E 00 O.00000 0.00000 0.00000 0.00000 0.00000 0.000001_6 0.31227E O0 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

Figure 7.5: Concluded

ORIGrNAL-PAGE IS

OF POOR QUALITY

115

Page 124: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

EXPERIMENTAL

THEORETICAL

VELOCITY (M/S) 129.00TEMPERATURE (C) -12.60

PRESSURE .(KPA) 90.75HUMIDITY (%) I00.00LWC (G/M s) 1.00DROP DIAM (MICRONS) 20.00

TIME (SEC) 120,00

Figure 7.6: Comparison of the experimental and calculated ice shapes for

Example 1.

116

Page 125: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

HACA 0012 : EXAMPLE 2&$24¥I£IFT- IIPkRA- lIFIRST- 3ZSEC_D# 3IPVOR z 1IHCLTs 0CLT= 4.0ICItORD = 0CCL= 0.0I)_D = 1ISOL= 0IPRIHT = 0IFLLL- 1_LND

1.0000000 0.98999990.9000000 0.87500000.7500000 0,72500000.6000000 0.57500000.4500000 0.42500000.3000000 0.27500000.15_0000 0.12500000.0600000 0.05000000.0250000 0.02000000.0037500 0.00250000.0012500 0.00100000.0003750 0.00025000.0003750 0.00050000.0012500 0,00150000.0037500 0.00500000.0250000 0.03000000.0600000 0.07000000.1500000 0.17500000.3000000 0.32500000._500000 0.47500000.6000000 0.62500000.7500000 0.77500000.9000000 0.92500001.0000000 0.00000000.0000000 -0.0018740

-0.0149080 -0.0179530-0.0318550 -0.0344110-0.0459040 -0.0479060-0.0560510 -0.0572430

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0.0029450 0.00346200.0058470 0.0064850

0.0106990 0.01238600.0262300 0.02846200.0385350 0.04103800.0336360 0.05587900.0602260 0.06009400.0560510 0.05469800.0459040 0,04379500.0318550 0,02922100.0149080 0.01170000.0000000 0.0000000

CTRAJ1GEPS= 0.4999999E-04DS_iIFT = 0.20E-02VEPS= 0.9999999E-03LC_B = 0L=HP= 0LE'_ = ILSY(I= 0LYOR= 1LXOR = 1HDDY= 1HEQ = qHPL = 15HSEAR = 50NSI= 1TI_STp= 0.9999999E-0__ENDCTRAJ2CHORD= 0.30G= 0.0PIT = 0.0PITDOT = 0.0PRATK = 0.0XORC # -4.0XSTOP_ 0.50YOLZM= 0,9999999E-04¥0MAXu 0.50E-01¥OMZH_ -0.50E-01YORC # 0.9999996E-01CEHD£DISTFLWC" 1.0, 9NO.ODPD# 20.0, 9_0.0CFP = 1.0, 9_0.0&END£1CEVIr(F z 129.460LWC- 0.50TAHB m 260,5498PArlBz 90748.0_Ha _00.0DPIIMz 20.0XI:IIIIT= 0.00035SEGTOL= 1.50&END

0.98000000.85000000.70000000.55000000.40000000.25000000.10000000.04500000.01500000.00225000.00087500.00012500.00062500.00175000.00750000,03500000.08000000.20000000.35000000.50_00000.65000000.80000000.95000000.0000000

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0.00393100.00707500.01507800.03049600.04325200,05757000.05970700.05319800.04158500.02651500.00825100.0000000

0.9700000 0.95000000.8250000 0.80000000.6750000 0.65000000.5250000 0.50000000.3750000 0.35000000.2250000 0.20000000.0900000 0.08000000.0400000 0.03500000.0100000 0.00750000.0020000 0.00175000.0007500 0.00062500.0000000 0.00012500.0007500 0.00087500.0020000 0.00225000.0100000 0.01500000.0400000 0.04500000.0900000 0.10000000.2250000 0.25000000,3750000 0.40000000.5250000 0.55000000.6750000 0.70000000,8250000 0.85000000.9700000 0.98000000+0000000 0.0000000

-0.0052390 -0.0082510-0.0237390 -0.0265150-0.0392810 -0.0415850-0.0515600 -0.0531980-0.0590900 -0.0597070-0.0587940 -0.0575700-0.0452280 -0.0432520-0.0323620 -0.0304960-0.0172480 -0.0150780-0.0076230 -0.0070750-0.0043630 -0.0039310

0.0000000 0.00163200.0043630 0.00476600.0076230 0.0081360

0.0172480 0.02079700.0323620 0.03408200.0452280 0.04700400.0587940 0.05961200.0500900 0.05826200.0515600 0.04979300.0392810 0.03688700.0237390 0.02088800.0052390 0.00361100.0000000 0.0000000

0.92500000.77500000.62500000.47500000.32500000.17500000.07000000.03000000.00500000.00150000.00050000.00025000.00100000.00250000.02000000.05000000.12500000.27500000.42500000.57500000.72500000.87500000.98999990.0000000

-0.0117000-0.0292210-0.0437950-0.0546980-0.0600940-0.0558790-0.0410380-0.0284620-0.0123860-0.0064850-0.0034620

0.00235600.00514600.0086200

0.02372600.03567400.05073200.06007600.05724300.04790600.03441100.01795300.00187400.0000000

60360360360360360360360360360360360360360360360360360360360360360360 SI I ,,$6046046O460460460460460 _.60 q60460460460460 q

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Figure 7.7: Input data file for Example 2

117

Page 126: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

V(LCCITY ¢M/$}

T[HPEEATUR[ (C)

F_[_SUq[ (KPA)

-UMI31TY (_)

L_ (3/H--3)

_R_P OI4M (MICRONS)

rIME (SIC)

129,00

-t2.&O

90.75

I00.00

0.50

20.C0

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X

VEL331TY (M'5) 129.00

TEHPER_TUQ[ (C) -[2.&0

P_[_SUQ[ (KPA) 90.75

-UMI_JTy (I) 100o00

_ (S"M-,3) 0.50

5R_P OlAM (M!CRONS) 20.09

TIME (SEC) 0.00

ORIGINAL PA(_E rS

OF. POOR QUALITY

0.2

Y 0.I3

-._ D 0

Figure 7.8: Plots of the particle trajectories calculated in subroutine

RANGE. i18

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VELOCITY (M/S) 129,00

T[HPE_TUQE (C) -L2.60

P_LSSUqE (KP_) 90._5

_U_I3ITY (_) lO0.OO

L_C (_./H--3) 0.50

_P Ol_M (MICRONS) 20.00

TIME (SEC) O.OO

C."

O.D

-. ='._

..... --v

III

I

o!o

VELOCITY (.M./5) 129,00

TEMPEEATUQE (C) -L2,60

P_[SSUq[ (KPA) 90o_5

-U_IDITY (_) 100.00

_A_ (_-'M--3) 0.50

_CP OIAM (MICRONS) 2O.Gg

_IME (SEC) O,O0

ORIGINAL:PAG- iS

OF POOR QUALITY

0.0

-°,_

I _.T.:-T._5____ ...........

Figure 7.8: Concluded

119

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0.5

0.0

-.2

_:ELCC1TY CM/$)

T_MPER_TURE (C)

P_LSSdR_ (KP_)

_U_I31TY (X)

L;_ (_./H--3)

CROP O[&M (MICRONS)

TIME (S_C)

129.00

-I2.60

90.75

IO0.OO

0.50

20.GO

0.00

ORIGINAL PAGE IS

OF POOR QUALITY

ix_= t IYO= -0.12000

S = -0,0_Z53

I

/

I

S

J °VELCCITY (.M/S) 129.00

T_MPER4/UR[ (C) -I2.&O

PRESSUR_ (KPA) 90.75

-_RI31TY (_) I00.00

LA_ (_/H--3) O.SO

C_P GI4M (H|C_ONS) 20.GO

TIM[ (S_C) D.O0

Y O.0

YO= -0.I1250 I

5 = O.01G:B !

I

iI f

I

Figure 7.9: Sample of the plots of the particle trajectories calculated in

subroutine IMPLIM.

120

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V[LCCITY (.N/S)

T_HPERATURE (C)

PRL_SUR£ (KPA)

_U_IDITY (_)

L_C f_,/H-=3)

C_2P GI4H (HICRON$)

129.00

-12.60

90.75

100.00

0.50

20.00

0.00

ORIGINAE PAGE iS

OF POOR QUALITY

0.2

T 0.0

-.2

!

!

J

l

J

l

0 +

Figure 7.9: Concluded

•I00 _-

-, 13_"

-.100 --

.II_ -

-.116

rv -.120 --

-. IZq" --

-.128 -

-. 13,_ --

-*136

- • I '_0._ 3B

o

0

o

o

o

o

o

o

o

o

o

o

o

S (H)

Figure 7.10:Y0 vs. s data calculated in subroutine COLLEC for Example 2

121

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ORIGINAl.. PAGE IS

POOR QUALIT _'VELOCITY (M/S) 129.9-6TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (X) I00.00

LWC (G/M,, ,, 3) O.SOOROP OIAM (MICRON) 20.00TIME (SEC) 80.00

a. Iced airfoil geometry

220 F

198 i

176

°°[I

22 _

do

-,lOt

..IO_ f-

-.135

I

_-..:_- [-

;

b. Particle release position vs. surface

impact distance

!.O r

o, Q L

_.8, L

I

:::E

c. Local collection efficiency vs. surfacelocation

o¢o_

o¢°_

^.::._ - ,_ . /

-27,e -

//

i •

c .?

e. Edge temperature vs. surface location

f,

_8

90

86

$2

78

7'+

;.Q _-._'_--:ca-._-._, -.'a; .%o _,"_;-_:.:_* :._, o."._o._-_-

$ cH_

Edge pressure vs. surface location

Figure 7.11: Icing parameter plots for the first timestep of Example 2.

122

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0

°:

-2

-3

G

-7

-8

-9

-_

g,

VELOCITY (M/S) 129.LF6

TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (%) IOO,OOLWC (G/M-- 3) 0.50DROP DIAM (MICRON) 20.00

TIME (SEC) 60,00

I" _,f

f

5 -oLd8 -.!21 -._;_ -._07 -.'00 0.107 0.';_ 0.!21 C.128 0.J35

S (H)

Equilibrium surface temperature vs.surface location

zOO0

900

800

700

600o

5OO

-- '_00

300

200

]OC

, 5 - ?28 - ,Iz [ - .11

ORI(_IIVA[ PA(_E IS

OF POOR QUALITY

j,

4 -.!o7 -.Jog oJo? O.PI_ o.121 C.'28 O.J3._

s (M)

Ice density vs. surface location

2C00

:EO0

:tO0

:200

zFbC

_C.C

Z:Z

h.

,OOCEO

•COC'_!

.000_!

.COO3!

.0003C

.OOOE5x

•GC_,20

,CC_: =.

.CCC;_

i,

•._--:.: -.'c; -Joo o.o7 o.i]'_ o.121 o.l_'e oJ35

S _M)

Convective heat transfer coefficient

vs. surface location

5 -.CE - -.i_ . i . IOO O :07 2.; _ O,?I G.2_ 0.'35

S (M)

Equivalent saad-grain roughness

height vs. surface ]ocatlon

1.0

0.8

0,7

O.o

0.5

0,_

D,3 !

0,2

0,1

0 _ B -.107 -,lOb -,105 -olOq" -o103 -oI(32 -.101 0o100 O,iOl 0.102

S (M)

k. Freezing fraction vs. surface location

Figure 7.11: Concluded

123

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: ! I ! f !-.IO -.OB -,06

0.10

0.08

0.06

O.Oq-

O.Og

I I f _.../

- • O'_" -sO,?. _''/_

/CALCULATED /STAGNATION POINTS--"

-,02

-.Dee

-.06

-.06

-.LO

n

p

m

w

f

• l I00 0.02.

i I l I I f ( fo.o_ 0.06 o.o6 o. I o

Figure 7.12: Locations of the multiple stagnation points in the second time

step of Example 2

124

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0.00Q

. .008

.,,OZO

Figure 7.13: Locations of the multiple stagnation points in Example 2 after

speciryingl new axes limits

).25

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0.020

O°Ot6

0.0_2

O.OOO

Y-.OOO -.OON" "_'-".1

- .009

-.OL2

-.016

I I 1 ItOO O.OOq O.0OB

//_I

,_ / ! ! I0.0[2 0.016 0.020

-.OZQ --

Figure 7.14: Iced airfoil with the pseudo-surface

126

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ORIGINAL PAGE I_

OF POOR QUALITY

_EL_ITY (.N/S) 127,00

T[MPER_TURE (C) -12,60

P_E55_ (KPA) 90.75

-C_I_ITY (X) lO0oOO

O_SP GlUM (MICRONS) 20.09

TIME (SEC) O.OO

-.100

-.tO_

-.tO0

-.112

-,I!6

v -,t20

0-.t2_

-.t28

-,t32

-.t36

-.I_Q,

F

ow

• ' •0

@

0

o

o

o

o

0

o

0

o

o

o

_._, .._, _._,, .._, .._,, _._,, -.in, o.£o o.fo, oJo,

S (M)

Figure 7.15:Y0 vs. s data calculated in subrouting COLLEC for the second

time step of Example 2

127

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a. Iced airfoil geometry

VELOCITY (M/S) 12g._6

TEMPERATURE (C> -12.60

PRESSURE (KPA) 90.75

HUMIDITY (%) I00.00

LWC (G/M--3) 0.50DROP OIAM (MICRON)20.O0

TIME (SEC) 120.00

196 I

]5_ F

Ello

86

66 _

"t2_

_.35

d,

OF POOR QUAU_Y

-.12B -.JZI -,lI'+ -.'07 ".lOG 0,_07 Ool]_ 0._21 0,128 O 135.

$ _M)

Edge velocity vs. surface location

-.lO0

-.I0_

-.IG8

-.112

--.1I¢

-.12Q

-.198

-.]32 I-.13¢

"'I_'_.zOB -,;O; -.'0¢ -.FOE -.;0_ -.lO3 -.;0_ -._31 0.100 O.'Oi O.102

S (M)

b. Particle release position vs. surface

impact distance

1.0

0,q

o. 8 //_

00:'-o/ /\

c._._o ._s _o3 -)c2 -.'_: c._oo o._o_ ; _.ro_"

S <M;

c. Local collection efficiency vs. surfacelocation

-2.0

-6.8

-9.2

-11.6

-16._=

-_: ._

-23,=

/

//

'c//

-2¢'_.".=E -.128 -,_21 -.ll_ -.'07 -.'CO 0.'C? O,l _" 0.'2: C.2E 0.I)5

S (H_

e. Edge temperature vs. surface location

]06

]02

q,,,

m. 86

82

f,

_. (M)

Edge pressure vs. surface location

Figure 7.16: Icing parameter plots for the second timestep of Example 2.

128

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oF sPOOR QUALITy

0

-1

-2

-3

3

on

-,_.9 p,

I

/

129._&-12.6090.75

IO0.OO0.50

(MICRON)20.OO120.00

10o0

9o0

Boo

7oo

z bOO

50C

-- _00 1

3O0

20C

]CO

0.35 -.I_6 -._l ..I -.=C7 -.CO C.'O_--C-.!:_ O.;_i 0°;28 0_35

E ,M_

j. Ice density vs. surface location

VELOCITY (M/S)TEMPERATURE (C)

PRESSURE (KPA)HUMIDITY (X)

LWC (G/M''3)DROP DIAMTIME (SEC)

JI

fJ

"]1_.135 -.'2_ -.J2! ".ll't ".107 -.100 0.107 0.!I _' C._21 072B 0.i35

5 (M)

g. Equilibrium surface temperature vs.surface location

_500

_OCO

:750

1500

_25o_:000

5OO

ho

LL

E

0.155 :-._28 -.'21 . I + -.'C; -.lO0 OJO7 0._:_ 0.'21 OJ2B--O'_J. 35

S (M)

Convective heat transfer coefficientvs. surface location

•O00SO F

.000_5_

.000_0_

• 00035 F

•00030 F

.COOISL

.00C05-

:.Z .... '

S (y)

i. Equivalent sand-grain roughness

height vs. surface location

k,

"°F 1O.e {'-

0.7

0°_

3°2 E

I

0._.'_6

Figure 7.16: Concluded

-.L37 -.,Co -.!05 -.C_ -JC3 -.'_- -.IcI 0.'0_ 0.101 O.J02

S IM)

Freezing fraction vs. surface location

129

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..... EXPERIMENTAL

THEORETICAL

VELOCITY (M/S) 129.00TEMPERATURE (C) -12.60

PRESSURE (KPA) 90.75

_ITY (_) mo.ooLWC (G/M s) 1.00DROP DIAM (MICRONS) 20.00

TIME (SEC) 120.00

Figure 7.17: Comparison of experimental and calculated

shapes for Example 2.

ice accretion

130

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NACA 0012 : EXAMPLE 3CS2q¥ILIFTs 1IPARA • 11FInSTa )ISECI;D, $IFVORe tI)ICLT" 0CLT = 0.0ICHORD z 0CCL= 0.0I_{D= IISOL _ 0IPRINT = 0YFLLL= I_EHD

1.0000000 0.98999990.9000000 0.87500000.7500000 0.7250000

.0.6000000 0.57500000.4500000 0.42500000.3000000 0.27500000.1500000 0.12000000.0600000 0.05000000.0250000 0.02000000.0037500 0.00250000.0012500 0.00100000.0003750 0.00025000.0003750 0.00050000.0012500 0.00150000.0037500 0.00500000.0250000 0.03000000.0000000 0.07000000.1500000 0.17500000.3000000 0.32500000.4500000 0.47500000.6000000 0.62500000.7500000 0.77500000.9000000 0.92500001.0000000 0.00000000.0000000 -0.0018740

-0.0149000 -0.0179530-0.0310550 -0.0344110-0.0459040 -0.0479060-0.0560510 -0.0572430-0.0602260 -0.0600760-0.0536360 -0.0507320-0.0385350 -0.0356740-0.0262300 -0.0237200-0.0106990 -0.0086200-0.0058470 -0.0051q60-0.0029450 -0.00235600.0029450 0.00346200.0058470 0.00648500.0100990 0.01238600.0262300 0.02846200.0385350 0.04103800.0536360 0.05587900.0602260 0.06009400.0560510 0.05469800.0459040 0.04379500.0318550 0.02922100.0149000 0.01170000.0000000 0.0000000

CTRAJIGEPS = 0.4999999E-04DSHIFT= 0.20£-02VEPS z 0.9999999E-03LCM8= 0LCrlP= 0LEOH = 1LSYM= 0LYOR= 1LXOR" 1PiBDY- 1HEQ= 4HPL = 15tlSEAR= 50HSI= IT_[ISTPs 0.9999999E-03C£_(DCTRAJ2CIIORD = 0.30G: 0.0PIT= 0.0PITDOT = 0.0pRAT_= 0.0XORC = -4.0×_T_P = 0.50YOLIrl = 0.9999999[-04YOtlAX= 0.50/-01¥0MXN= -0.50E-01YORC z 0.9999996E-01EErZD_DISTFLWC= 1.0, 9*0.0DPD = 20.0, 9wO.OCFP= 1.0, 9w0.0CE?ID&ICEVIHF= 64.72_LWC= 0.500TAMB= 200.55PAIIB= 90748.0RI{= 100.0DPM;1 = 20.0XKIPIIT= 0.25E-03SEGTOL= 1.50CEND

0.9800000 0.9700000 0.9500000 0.92500000.8500000 0.8250000 0.8000000 0.77500000.7000000 0.6750000 0.6500000 0.02500000.5500000 0.5250000 0.5000000 0.47500000.4000000 0.3750000 0.3500000 0.32500000.2500000 0.2250000 0.2000000 0.17500000.1000000 0.0900000 0.0800000 0.07000000.0qS0000 0.0400000 0.0350000 0,03000000.0150000 0.0100000 0.0075000 0.00500000.0022500 0.0020000 0.0017500 0.00150000.0008750 0.0007500 0.0006250 0.00050000.0001250 0.0000000 0.0001250 0.00025000/0006250 0.0007500 0.0008750 0.00100000.0017500 0.0020000 0.0022500 0.00250000.0075000 0.0100000 0.0150000 0.02000000.0350000 0.0400000 0.0450000 0.05000000.0800000 0.0900000 0.1000000 0.12500000.2000000 0.2250000 0.2500000 0.27500000.3500000 0.3750000 0.4000000 0.42500000.5000009 0.5250000 0.5500000 0.57500000.6500009 0.6750000 0.7000000 0.72500000.8000000 0.8250000 0.8500000 0.87500000.9500000 0.9700000 0.9800000 0.98999990.0000000 0.0000000 0.0000000 0.0000000

-0.0036110 -0.0052390 -0.0082510 -0.0117000-0.0208880 -0.0237390 -0.0265150 -0.0292210-0.0368870 -0.0392810 -0.0q15850 -0.0437950-0.0497930 -0.0515600 -0.0531980 -0.0546980-0.0582620 -0.0590900 -0.0597070 -0.0600940-0.0596120 -0.0587940 -0.0575700 -0.0558790-0.0470040 -0.0452280 -0.0432520 -0.0410380-0.0340820 -0,0323620 -0.0304960 -0.028_620-0.0207970 -0.0172400 -0.0150780 -0.0123860-0.0081360 -0.0076230 -0.0070750 -0.006_850-0.0047660 -0.0043630 -0.0039310 -0.003_620-0.0016320 0.0000000 0.0016320 0.0023560

0.0039310 0.0043630 0.0047660 0.00514600.0070750 0.0076230 0.0081360 0.00862000.0150780 0.0172480 0.0207970 0.02372600.0304960 0.0323620 0.0340820 0.03567400.0432520 0.0452280 0.0470040 0.05073200,0575700 0.0587940 0.0596120 0.06007600.0597070 0.0590900 0.0582620 0.05724300.0531980 0.0515600 0.0_97930 0.04790600.0415830 0,0392810 0.0368870 0.034_1100.0265150 0.0237390 0.0208880 0.017_5300.0082510 0.0052390 0.0036110 0.00187400.0000000 0.0000000 0.00000o0 0.0000000

ORIGINAl/PAGE IS

OF POOR QUALITY

0 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 3I 30 40 40 40 40 400 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 41 4

Figure 7.18: Input data file for Example 3.

131

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OF. POOR QUALIfy

a. Iced airfoil geometry

VELOCITY (M/S) 6q.73TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75

HUMIDITY (X) IOO.O0LNC (G/M,, ,,3) O.SODROP DIAM (MICRON)20.ODTIME (SEC) 60.00

:oc F,_0 L

BC "

zc_- ,/;'°" f Ii

i V_ so

"> _'0 _-

2G -I

:o,_ i£ -.26 -.)i -.i- -._; -._,C C.'C 7 C.I" C,.21 C.2E £.._

S t_:

d. Edge velocity vs. surface location

O,OICq

0.006 _-

C.OO6

!

O.O0 W _-

__.o_FO.OOO r

_-.ooa L!

-.00_ i-

-.00_

ff

J

-oOCB i

b. Particle release position vs. surface

impact distance

-10.=. -

-;].C _-

i_::.c r-

. . , . ,

^-:2.C _-

_.:2.= -i

_'- _ :-. C -

-:-.C -

'i

J

r I i'

? (_,,

e. Edge temperature vs. surface location

_.0

G._

O.e

0.7

0.6

,LO.5

h"

0.3

0.]

_.C

I /

F /I3;_ -_ . _ -.005 0.o05 C.o]5 o. _,_=.

S (_

Local co1|ectionefficiencyvs. surface

location

IO0

I

Qe L

- 90

" ia $8

f,

82 r"

B_.35 ._E -,21 -.I- -.G7 -.00 _.C: C.:- .:._: _._6 C,.:._

S (*_,

Edge pressure vs. surface location

Figure 7.19: Icing parameter plots for the first timestep of Example 3.

132

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ORIGINALPACE |SOF POOR QUALITY

VELOCITY (M/S) 6°r. 73TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (X) I00o00

LHC (G/M" N3) 0o50DROP OlAM (MICRON) 20oOOTIME (SEC) 60.00

0.0 -

-3,0 !"- I

_-7.5

--9.0 -

I

-12.C i

-X3,5 L-I

-: .Co'_ -.'2_ -._.i -o:,t .;07 -.o_

Equilibrium surface temperature vs.

surface location

g.

IOOG E90C

8CG 1-

I

;'05 _-

_oo_LSOD

-- _.00 _-

300 t

20C E_00

j.

I' ' I ' ' ' '

_ b -.2E -.21 -.i- o.'O; -._ rz.'_7 G.':'. 0.'2_ :..2E G.3E

S (M_

Ice density vs. surface location

e

hQ

80O 7

?20

_'_0

_OO _ /

- .o _

eC - f

_.'_5 "o2_ -o2i _ I:,+ -.O? -oGG O.C_ C.I- C.21 Co29 Oo._E

Convective heat transfer coe_icient

vs. surface location

Io0

0,?

0.8

0.5

C.'+

0.3

°.I

O.C

ko

, KM)

Freezing fraction vs. surface location

.CO0"5_

oCCO_G_

.CO0_O

oC°015_

• CCC:O r

.CCCC_ I-.=_ -._= -°'_: -.':- -.i_7 -.'OC C.'C: C _.'_:

i.

-.;Z_. C.=E

Equivalent sand-grain roughness

"height vs. surface location

Figure 7.19: Concluded.

133

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a. Iced airfoil geometry

VELOCITY (M/S) 6ur.73TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (X) 100.00LWC (G/M,,,,3) 0.50DROP DIAM (MICRON) 20.00TIME (SEO) 120.00

O0

72

&_

56

_, _e

_ 32

16

$

Q,

d*

ORIGINAL PAGE IS

oF POORQUALITY.

5 -.t28 -.r21 -.IN -707 -._0 C.':17 0.l_ C,.2I 0.128 0,'_5

5 (e)

Edge velocity vs. surface location

0"01C F

oi0o_!

_.00_

O,OOC

_-.oo2

-.OON

m'O0 _

-.00£

-,olq

b,

S (M)

Particle release position vs. surface

impact distance

"°I0.9

0.8-

O,l

0.6

_o.5

_o._

0.3

0,2

0.]

o.o

'5 0.025

$ (M)

Local collection efficiency vs. surfacelocation

-I0,0

-10.5

-II.5

"' .]3. r

-13.£

- I ",. C

-]_.£

"15"-_,!35 -.!2@ -.:?i -.ll" -.!07 -.loc G.'G7 O.'l _ 0.'_1 0.F28 0.1_5

S (M)

e. Edge temperature vs. surface location

]00

96

9_

90

c_ 88

06

11'4

f,

82

80" 5 -- "12 _ I *'_ i I " ] _ " " 0 ? m " 00 &.'Of 0.!I'_ 0.2] O.12B 0.135

S (H;

Edge pressure vs. surface location

Figure 7.20: Icing parameter plots for the second timestep of Example 3.

134

Page 143: Users Manual for the NASA Lewis Ice Accretion Prediction ... · Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) Gary A. Ruff and Brian M. Berkowitz Sverdrup

VELOCITY (M/S) 6°r. 73TEMPERATURE (C) -12.60PRESSURE (KPA) 90.75HUMIDITY (X) lO0.O0LNC (G/M"" 3) 0.50DROP OIAM (MICRON) 20.00TIME (SEC) 120.00

-0.0 I°I ,2

-2.'+ F"

-3,a _-

I

_ob.O

-10.8 L

":2"_.'3_ -.'28 -.'_'; -.I1_ -._07 -.100 0._0t O._l ", 0°'2; 0.'_5 0._35

S (M)

g. Equilihxium surface temperature vs.surface location

1000

900

800

700

z 600

_ 500¢J- _00

300

2OO

100

jo

PAGEisOF POOR QUALITY

5 -o:28 -.'21 -o'_V -o07 -.100 O.fO/ 0.'1_ 0.12| 0.25 0ol35

5 (M)

Ice density vs. surface location

600

5_C

_,80

_20

360

3oo=

2_c

180

_20

bo

h,

.00050

.0004

.ODOr,

.0003!

.00030

.00025

w.00020

,00015

.00010

.00005

.O000C-,:

L

!I ////

FJ' !-. '26 " i ...._-135 -,_ -,':* -,'_; -,'0C 0,'07 0,1_ 0°'21 3°28 0,'3_

¢. {M)

Convective heat transfer coe_cientvs. surface location

1,0

0,9

0.5

0,?

0,b

0,5

0,3

0,'2

0,!

0,.Cl

ko

°,"_'E -,l_l °,]1_ -,'07 -,'00 0°IOF o,i;_ G,'_I Oo;2B 0.135

$ (M)

Equivalent sand-grain roughnessheight vs. surface location

Figure 7.20: Concluded

W

5 -.o,s -._05 0._05 0.6_5 0._5S (M)

Freezing fraction vs. surface location

135

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EXPERIRENTAL

THEORETICAL

VFLDC|TY (H/S) 6_.73

T[HPERATUR[ (C) -|2.60

PRESSURE (KPA) 90.76

HUMIDITY (_) 100.00

LHC (G/N--3) 0.60

DROP D[AH (HiCRONS) 20.00

TINE (SEC) 120.00

Figure 7.21: Comparison of experimental and calculated ice accretion shape

for example 3.

136

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F

b-

0,10 --u..

10 20 30DROPLETDIAMETER,d, pM

Iqo

Figure 7.22: Droplet distribution specified for Example 4.

1,0(} m

.80--

.qo

.20

10 20 30 qo

DROPLETDIAMETER,d, MM

Figure 7.23: Cumulative volume fraction vs. droplet diameter for the

droplet distribution specified in Example 4.

137

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HACA 0012 : EXAMPLE 6

E324¥ILIFT = 1

IPARA= 1

ZFZRSTS 3

ISECHDs 3

IPVOR" 1

IfICLTs OCLT z 0.0

ZCHORD = 0

CCL a 0.0ItlD = 1

ISOL" 0

ZPRZHTz 0IFLLL • 1

CEND

1.0000000 0,98999990.9000000 0.8750000

0.7500000 0.7250000

0.6000000 0.5730000

0.4500000 0.42500000.3000000 0.2750000

0.1300000 0.1250000

0.0600000 0.0500000

0.0250000 0.02000000.0037500 0.0025000

0.0012500 0.0010000

0.0003750 0.00023000.0003730 0.9005000

0.0012500 0.0015000

0.0037500 0.00500000.0250000 0.0_00000

0.0600000 0.07000000.1500000 0.1750000

0.3000000 0.3250000

0.4500000 0,6750000

0,6000000 0.62500000.7500000 0.7750000

0.9000000 0.9250000

1.0000000 0.0000000

0.0000000 -0.0018740

-0.0140080 -0.0179530

-0.0318550 -0.0344110

-0.0459040 -0.0479060

-0.0560510 -0.0572430-0.0602260 -0.0600760

-0.0S36360 -0,0507320

-0.0385350 -0.0356740

-0.0262300 -0.0237260

-0.0106990 -0.0086200-0.0058470 -0.0051460

-0.0029450 -0.0023S60

0.0029450 0.0034620

0.0058470 0.0064850

0.0100990 0.01238600.0262300 0.0284020

0.0385350 0.0410380

0.0536360 0.0558790

0.0602260 0.0600940

0.0560510 0.0566980

0,0459040 0,04379500.0318550 0.0292210

0.0149080 0.0117000

0.0000000 0.0000000

CTRAJ1

GEPS_ 0.4999999E-04DSHIFTz 0.20£-02

VEPS" 0.9999999E'03

LCM8= 0LCMP" 0

LEQM= 1

LSYM = 0

LYOR" 1LXOR= I

tlBDY= I

/lEO= 4

- HPL- 15HSEAR" 50

NSI- 5

TIMSTPm 0.9999999E-03

CEHD

CTRAJ2

CHORD- 0.30

O = 0.0PZT= O.0

PITDOT- 0.0

PRATK z 0.0

XORC= -4.0

XSTOP- 0.50

¥0LIM- 0.9999999E-04YOMAX _ 0.50E-Ol

YOMZH- -0.$0E-01

¥ORC- 0.9999996E-0I

CEND

CDZST

CFPw 1.042, 4_1.0, 5N0.0

0.9800000 0.9700000 0.9500000

0.8500000 0.8250000 0.8000000

0.7000000 0.6750000 0.6500000

0+5500000 0.5250000 0.50000000.4000000 0,3750000 0.3500000

0,2500000 0.2250000 0.2000000

0.1000000 0.0900000 0.0800000

0.0450000 0.0400000 0.03500000.01_0000 0.0100000 0.0075000

0.0022500 0.0020000 0.0017500

0.0008750 0.0007500 0.00062500.0001250 0.0000000 0.0001250

0,0006250 0.0007500 0.0008750

0.0017500 0.0020000 0.00225000.0075000 0.0100000 0,0150000

0.0350000 0.0400000 0.04500000.0800000 0.0900000 0.1000000

0.2000000 0.2250000 0.2500000

0.3500000 0.3790000 0.40000000.5000000 0.5250000 0.5500000

0.6500000 0.5750000 0.7000000

0.8000000 0.8250000 0.8500000

0.9500000 0.9700000 0.9800000

0.0000000 0.0000000 +0.0000000

-0.0036110 -0.0052390 -0.0082510

-0.0208880 -0.0237390 -0.0255150

-0.0368870 -0.0392810 -0.0415850

-0.0497930 -0.0515500 -0.0531980-0.0582620 -0.0590900 -0.0597070

-0.0596120 -0.0587940 -0.0575700

-0.0470040 -0.0452280 -0.0432520

-0.0360820 -0.0323620 -0.0304960

-0.0207970 -0.0172480 -0.0150780

-0.0081360 -0.0076230 -0.0070750-0.0067640 -0.0063630 -0.0039310

-0.0016320 0.0000000 0.00103200.0039310 0.0043530 0.0047660

0.0070750 0.0076230 0.0081360

0.0150780 0.0172480 0.02079700.0304960 0.0323520 0.0340820

0.0432520 0.0452280 0.0470040

0.0575700 0.0587940 0.0596120

0.0597070 0.0590900 0.0582620

0.0531980 0.0515600 0.0497930

0.0415850 0.0392810 0.0368870

0.0255150 0.0237390 0.02088800.0082510 0.0052390 0.0036110

0.0000000 0.0000000 0.0000000

DPD- 4.0, 12.0o 20.0, 28.0, 36.0, 5"0.0

FLWC = 0.0082, 0.2037, 0.5762, 0.2037, 0.0082, 5_0.0

_ENO

CICEv2ttr= 129,460

L_C- 0.750

TArIB_ 260.5498

PAM8= 90748.0

RH = I00.0

DPMM" 20,0

XKIHIT: 0.00035SEGTOL s 1.50

CEHD

0.9250000

0.7750000

0.62500000,4750000

0.3250000

0.1750000

0.07000000.0300000

0.0050000

0.0015000

0.00050000.0002500

0.00100000,0025000

0,0200000

0.05000000.1250000

0.2750000

0.42500000.5750000

0.7250000

0.8750000

0.9899999

0.0000000

-0.0117000

-O.0292210

-0.0437950

-0.0546980-0.0600940

-0.0558790

-0.0410380

-0.0286620

-0.0123860

-0,0054850-0.0034620

0,00235600.0051660

0.0086200

0,02372600.0356740

0.0507320

0.0600760

0.0572430

0.0479060

0.0344110

0.01795500.0018740

0.0000000

603

603

603603

603

603

603603

603

603

603603

603603

603

603603

603

603

0 0 3603

603

603

1 I 3

604

604

604604

604

604

604

604

604

6 0 q604

604604

6 0 ¢t,

604604

604

0 0 4

604

0 0 4

604

604604

11 4

Figure 7.24: Input data file for Example 4.

138

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ORIGINAL PAGE IS

OF POOR QUALITY

a. Iced airfoil geometry

VELOCITY (M/S) 129.'_6TEMPERATURE (C) -12,60PRESSURE (KPA) 90.75

HUMIDITY (X) IO0.OOLWC (G/M w" 3) 0.75DROP DIAM (MICRON)20.O0TIME (SEC) 60,00

0,01. _

0,0]_

0.00_

0.00

_o.oo

0.00(o

-.00_

-.OOd

-. 00'_

-,Of;

o:,

de

,0-._'+S-._36 -.{_Z4 -._lZ'-.O00 0.(_12 0._2'+ 0._3_ O._e 0.-'_60

$ (M)

Particle release position vs. surface

impact distance, d,_ = 20 microns

°.°'i_0.9)

0.009

O,O0o

_-o.oc3

o 0"000 j

-.003

-.OOb

. .000

" "O121_"_-:? o -._--.(_, -._, -._,_ -.,%oo._ o._2, o.(_, o._, o._,o$ (M}

b. Particle release position vs. surfaceimpact distance, d,_ = 4 microns

0.0;_

C.O_2E

O'OCc !

O.O0_'

0.000

_-.003

-,00_

"'°°qi!-.0;2

S (M)

e. Particle release p_osition vs. surfaceimpact distance, d,_ = 28 microns

O.OI5_ O.OIS

0,0121 O.OIE

0.009 1 0.009

O.OOb 0.006

_0.003 _0.003

0,000 i _0"000>o.003 _-.003

-.O0oL -.006

-.0091 -.009

.O_Ef6 -.012

.o:so-._5-._.-.;_, -._ -.;ooo.;:_o.o__.;_. o.;,_o._,o -.o_,S (M)

c. Particle release p_osition vs. surface f.impact distance, d,_ = 12 microns

J

_,6 _6 _2. _2 .6ooo.6_o._,o._,o.6,o.66oS (M)

Particle release p_osition vs. surfaceimpact distance, d,. = 36 microns

Figure 7.25: Icing parameter plots for the first timestep of Example 4.

139

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:.z --

i.: .-

,3 ,

/i

//

//

/

VELOCITY (M/S)TEMPERATURE (C)

PRESSURE (KPA)

HUMIOITY (X)

LWC (G/MwN3)

OROP OIAM

TIME (SEC)

0.060

\

\

,,\

ORIGINAl: PAaE_is12 9. _ 6 OF POOR QUALITY-12.60

90.75

I00.000.75

(MICRON) 20.00

60.00

!:0 i

107

(

j. Edge pressure vs. surface locationLocal collection efficiency vs. surface

location

h,

hfi

i

I

' ," i .-, " .'C -T -': .7_ 3 -C .-J __.._=_1_ ; --O .'2 i 0 .I_8 O.135

3

Edge velocity vs. surface location

o

-1

-2

-3

u_-6

-I

-8

-q

-I0

k.

'35 -.z28 -.'21 -.If'," -.;OT'_-.-_,'_.-JC_ - OJl_ 0._21 0_\___=-

S c,')

Equilibrium surface temperature vs.surface location

2

"'.-L . ÷ -., . " ._" *.3'- C._, u.: W _.2; G._g8 0J35

Edge temperature vs. surface location

1500

1350

1200

1050

_0O

_sobOO

_50

3O0

150

g.

l,

' "- J_e - ._ ! - .zl ',' - JOT---; _;%--c ._'t', _- C,.; .:" o T2 : -i', J, L_, ,

S ,H:

Convective heat transfer coefficient

vs. surface location

Figure 7.25: Continued.

140

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ORIGINAt PAGE IS

OF POOR QUALITY

VELOCITY (M/S) 129._6TEMPERATURE (C) '12.60PRESSURE (KPA) 90.75HUMIDITY (%) I00.00LHC (G/M"" 3) 0.75DROP DIAM (MICRON) 20.00TIME (SEC) 60.00

• OOOSO F

.O00_SL

.OOC_O

.00035

.00030

.00025

*00020

.000i5

.000)0

.00005

.ODD00

m,

5 -.I2B -.'2l -.Ii_ -.!Of -[00 O.TG; O.::_ O.i_I 0J26 C

S (M)

Equivalent sand-grain roughness

height vs. surface location

10oo

_00

BOO

700

z _00

SO0

-- _OG

30O

200

_00

0[35 -.i26 -J2i _.I_

-.IO; -,I00 O.'O? O.'_ 0721 Oo!_B 0.1)5

S _M)

Ice density vs. surface location

1.0

0.9

0,8

0,7

0.6

0.5

0.3

0.2

0.1

O.&

O,

o ' -.6_, ' -.6,_ ' o.6,2 ' o._, ' o.AoS (M)

Freezing fractionvs. surface location

Figure 7.25: Concluded.

141

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l--

t_JIx]

i.O

0,9

0.II

0.#

0.6

O.S

O,,e-

O.3

0.,?

0.I

o.o

NACA0012 AIRFOIL

NORMALDISTRIBUTION

140NODISPERSED

DISTRIBUTION

/ \

-.°3, -._, _,_ .ho o._,, o.'_+, o._,o

S (M)

Figure 7.26: Comparison of the calculated local collection efficiency vs.

surface distance for a normal and monodispersed droplet distributions with

mass median diameters of 20.0 microns.

f- ELECTROTH_R/_d.HEATER/

//

,Ill'Figure 7.27:

Example 5.

Electrothermal heater on a NACA 0012 airfoil modeled in

142

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HACA 0012 : THERMAL A/!CS2qYILIFT = |ZPARA m 1IFIRST" 3ISECNns 3ZPVOR- 1INCLT s 0CLT= 6.0ZCHORD= 0CCL = 0.0I)¢Dz IISOL= 0IPRIHT" 0IFLLL= I&EHD

1.0000000 0,98999990.9000000 0.87500000,7500000 0.72500000.6000000 0.57500000.6500000 0.62500000.3000000 0.27500000.1500000 0.12500000.0600000 0.05000000.0250000 0.02000000.0037500 0.00250000.0012500 0.00100000.0003750 0,00025000.0003750 0.00050000.0012500 0.00150000,0037500 0.00500000.0250000 0.03000000.0600000 0.07000000.1500000 0.17500000.3000000 0.32500000,6500000 0.¢750000O.buO050O 0.62500000.7500000 0.77500000.9000000 0.92500001.0000000 0.00000000,0000000 -0.0018760

-0,0169000 "0.0179530-0,0318550 -0.0366110-0.0_590_0 -0.0679060-0.0560510 -0.0572630-0.0602260 -0.0600760-0.0536360 -0.0507320-0.0385350 -0.0356760-0.0262300 -0.0237260-0.0106990 -0.0086200-0.0058670 -0.0051660-0.002?450 -0.0023560

0,0029_50 0.00366200.0058470 0.00668500.0106990 0.01238600.0262300 0.02866200.0385350 0.06103800.0536360 0.05587000.0602260 0.06009¢00.0560510 0:05669800.0659060 0.06379500.0318550 0.02922100.01_9080 0.01170000.0000000 0.0000000

&TRAJI

0.0800000 0.9700000 0.95000000.8500000 0.8250000 0.80000000.7000000 0.6730000 0.65000000.5500000 0.5250000 0.50000000.q000000 0.3750000 0.35000000.2500000 0.2250000 0.20000000.1000000 0.0900000 0.08000000.0¢50000 0.0_00000 0.03500000.0150000 0.0100000 0.00750000.0022500 0.0020000 0.00175000.0008750 0.0007500 0.00062500.0001250 0.0000000 0.00012500.0006250 0.0007500 0.00087500.0017500 0.0020000 0.00225000.0075000 0.0100000 0.01500000.0350000 0.0¢00000 0.06500000.0800000 0,0900000 0.10000000.2000000 0.2250000 0.25000000.5500000 0.3750000 0.60000000.5000000 0.5250000 0.55000000.6500000 0.6750000 0.70000000.8000000 0.8250000 0.85000000.9500000 0.9700000 0.58000000.0000000 0.0000000 , 0.0000000

-0.0036110 -0.0052390 -0.0082510-0.0208880 -0.0237390 -0.0265150-0.0368870 -0.0392810 -0.0615850-0.0697930 -0,0515600 -0.0531980-0.0582620 -0.0590900 -0.0597070-0.0596120 -0.0587060 -0.0575700-0.0670060 -0.0652280 -0,0632520-0.0360820 -0.0325620 -0.030_960-0.0207970 -0.0172680 -0.0150780-0.0081360 -0.0076230 -0.0070750-0.0067660 -0.0063630 -0.0039310-0.0016320 0.0000000 0.0016320

0.0039330 0.0063650 0.00676600.0070730 0.0076230 0.00813600.0150780 0.0172680 0.02079700.0304960 0.0323620 0.03608200.0632520 0.0652280 0.06700600.0575700 0.0587940 0.05061200.0397070 0.0590?00 0.05826200.0531980 0,0515500 0.06979300.0615850 0.0392610 0.03588700.0265150 0.0237390 0,02088800.0082510 0.0052390 0.00361100.0000000 0.0000000 0.0000000

GEPS = 0.6999909E-06DSHZFT = 0.20E-02VEP5= 0.0990099E-03LCMB= 0LCrlP _ 0LEQM = ILSYM: 0LYOR= 1LXOR # I);BDY= 3HEO: 6HPL= 15IISEAR= 50HSZ= 3TZI1STP = 0.0909999E-03CEIIDCTRAJ2CIIORD = 0.30G- 0.0PIT= 0.0PITDOT- 0.0PRATK • 0.0XORC 2 -4.0XSTOP= 0.50YOLIM= 0.9999999E-0_¥OMAX = 0.50E-01YOM171= -0.50E-01¥ORC = 0.9999996E-01_E.D&DISTCFP=I.0, 9_0.0DPD=20.0, ?_0.0FLt4C=I.00, 9e0.0CEr<D£ICEVIHF= 128,608LHC= 0.500TAMB: 265.00PAMS= 90768.0RH= 100.0DPMM= 20.0XKIHIT: 0.20E-03SEGTOL= 1.50QCOHD=Sq"0.0,71N6000.,]95N0.0_EHD

0.92500000.77500000.62500000,47500000.32500000.17500000.07000000.03000000.00500000.00150000.00050000.00025000.00100000.00250000.02000000.05000000.12500000.27500000,62500000.57500000.72500000.87500000.98999990,0000000

-0.0117000-0.0202210-0.0437950-0.0566980-0.0600960-0.0558790-0,0610380-0.028_620-0.0123860-0.0066850-0.0036620

0.00235600.00516600.00862000.02372600.03567600.05073200.06007600.0572_300.0¢790600.03661100.01795300.00187_00.0o0o0oo

ORIGINAL PAGE IS

OF POOR QUALITY

603603603603603603603603603603603603603603603603603603603603603603603I [ 36 0 66066066 0 _,6 0 c,6066066066066066066066066066 0 ¢6066066065 0 66066 0 q60¢606I I ¢

Figure 7.28: Input data file for Example 5.

143

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I-ICE ACCRETIOfl

/ ON THE HEATER

I

/

I

_--ICE ACCRETION

AFT 0F THE HEATER

a. Iced airfoil geometry

ORIGINAL F_E'_ _S

OF POOR QUALITY

VELOCITY (M/S)TEMPERATURE (C)PRESSURE (KPA)HUMIDITY (X)

LWO (G/M.N3)DROP DIAM (MICRTIME (SEC)

[email protected]

IO0oO00.50

ON)20.O060.00

\

S

2_F'Q.'35 -.128 -.;21 -.;1'+ -.107 -.;OC

S _M)

d.

25O

225

200

175

150

125

log

75

50

c.'o__FT:__:'_

Edge velocity vs. surface location

-.:oC .

-.:0- L.

L-.;72 F

_:..: 7_ L

-.;_C L

S/

_:: :_., _-. _-.-T_;.:,_._2_;_.._o-o._oeo._ao

Particle release position vs. surface

impact distance

- i

2,? -

5.1 "-

S :=)

c. Local collection efficiency vs. surfacelocation

o

-3

-6

-9

-IE

-15

._

-El

-El

-30

e.

I]0

105

tOO

_. _0

1S

70

f.

bS

/._f /

;, *.L_8 -.l_l -,ll'f -?07 -.106 0.[07 C,ll_ 0.12; 0.128 0.13_

S (M)

Edge pressure vs. surface location

Figure 7.29: Icing parameter plots for the first time.step of Example 5.

144

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ORIOINAE PAGE |S

OF POOR QUALITY

5

3

2

I

0

-2

-3

go

VELOCITY (M/S) 128._I

TEMPERATURE (C) -8.15PRESSURE (KPA) 90.75HUMIDITY (%) IOO.O0LWC <G/M,*3) 0.50DROP DIAM (MICRON)20.OOTIME (SEC) 60.00

Jf

f

-.'2, -.'2, -.',_ -.'o, -.'oo o.'_, o.'_* o.'_, o_8 °/35S (#4)

Equilibrium surface temperature vs.

surface location

I000 I

QO0

• 70G

_°°° I50C

)OC -

200 l

)OC [-

J,

I ,iJ

f_.'35 - .'_'8 - .;2 i --.11 _' - .PO7 - .IO0 0.:07 G ,11'_ 0.I_ ] 0.'28 0.J35

Ice density vs. surface location

_800 II_20

]2bO

1080 _

120

]80 _-

_.l .. fi . I t . .I _ - .10_ -._(lO 0.107 0.11 • 0.:_ l O.'E8 0.f35

$ (M)

h. Convective heat transfer coefficientvs. surface location

],0

0.9

0,8

0.7

0.6

0o_

0.3

0°2

0ol

o..o

k,

' -.b_ "_"_-.&_ _ -.(_8 _ -._o_ _o0 .

$ (M)

Freezing fraction vs. surface location

o00050 c

•000'_5_-

.O00EO_

.OOOlS_

:Oo:Oo::F.C_O_0%_ -.:2e -.:,?.t -._;_ -.TO;' -.roo o.lo_ o._t,_ e._t 0._,?,8 o._,s

S (M)

i. Equivalent sand-grain roughness

height vs. surface location

Figure 7.29: Concluded.

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Chapter 8

PROGRAMMING AIDS

This section contains information regarding the coding of LEWICE to aid

users who require a more advanced understanding of the program. Descrip-

tions of the subroutines, common blocks, and work files are included, along

with flow charts of various sections of the program.

8.1 Descriptions of Subroutines

The subroutines will not be discussed individually in this user's manual.

Instead, a description can be found in the program listing in COMMENT

statements preceding most subroutines. These descriptions include the pur-

pose of the subroutine, the input and output variables, and additional notes

describing special features of the subroutine.

8.2 Diagnostic and Error Messages

In a program as complex as LEWICE, the programmer must provide mes-

sages informing the user of any abnormalities in the calculations. The most

common error messages are discussed in this section. They are grouped by

the program module in which they will occur, i.e., potential flow calcula-

tion, particle trajectory calculation, or thermodynamic and ice accretion

calculation.

When an error message or unusual situation occurs, the first step should

be to check the description of the input parameters found in Section 5.0.

The following descriptions of the error messages will assume that this step

has already been completed, and will concentrate on how the error may

relate to certain aspects of the icing condition or geometry being evaluated.

8.3 Potential Flow Calculations

All of the lines of data input to the potential flow code are identified by

a card type number found in the most right-hand column in each line of

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data. When the data line is read, this value is checked against the value

of the card type that was anticipated. If these numbers do not match, an

error message is printed and the program terminated. This error condition

is usually caused by having input values in the wrong columns on a line of

data.

Another error occurs occasionally when stagnation points are calculated

behind (downstream) of the large horns of a glaze ice accretion. The error

will usually be characterized by _division by zero" messages. The situation

cannot be corrected by forming a pseudo-surface as described in Section 7.2

and Appendix C. However, the case should be re-run with a larger timestep

which will make the predicted glaze ice accretion somewhat smoother and

may allow the calculations to continues.

Another error condition can occur when multiple stagnation points are

calculated which cannot be removed by the formation of a pseudo-surface,

and a stagnation point has been manually selected. In this case, there will

be at least two locations where the local velocity is 0.0 m/s. When the

compressible, dimensional surface velocity is calculated from the incom-

pressible, non-dimensional values (subroutine VEDGE), division by zero

errors can again occur. It is best to force the calculations to continue

through this error, if possible, because the locations of the error may be

downstream of the impingement region and, therefore, will not affect the

ice accretion shape. If the calculations cannot be continued, re-run the case

with a larger timestep.

8.4 Particle Trajectory Calculations

Most of the errors that occur in the particle tr_ectory calculations result

from inaccuracies in the flow field or errors in input data. Errors caused

by improper input parameters will generally be accompained by diagnostic

messages, which will be discussed below.

Subroutine RANGE will allow a total of 30 trajectories to be calculated

while searching for a trajectory that passes above and below the body.

If two such trajectories are not identified, the following message will be

printed and the program stopped:

30 Trajectories are calculated in RANGE. Run aborted.

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The most probable cause of the error is that the values of YOMAX and

YOMIN have been input incorrectly. If the values are correct, review the

body coordinates that are being used by the program.

A run can be terminated in a similar manner in subroutine IMPLIM. In

this case, if the number of trajectories required to identify the upper and

lower impingement limits exceed NSEAR, the run is terminated. The value

of NSEAR is input by the user through namellst TRAJ1 and is normally

set equal to 50. If the limiting value of NSEAR is reached, the value of

YOLIM may be unnecessarily small or there may be a problem with the

way the program has read or interpreted the body coordinates.

In subroutine COLLEC, the program will be terminated if the value of

NPL is greater than 100. The value of NPL is input by the user through

namelist TRAJ1, and typical values are between 10 and 20. If this error

occurs, verify that the value of NPL is in the proper column in the input

file.

Occasionally, errors occur in the flow field near the surface of the body,

especially for convoluted glaze ice accretions. In these cases, very large

local velocities are calculated which cause exponent overflows or negative

arguments in subroutine ABFORM. If these errors occur, try to force the

calculations to continue through this error because, if a bad impingement

point is calculated as a result of the error, it can removed before calcu-

lating the local collection efficiency. Unfortunately, once this error has

been encountered in one timestep, it will probably occur in all subsequent

timesteps.

8.5 Thermodynamic and Ice Accretion Calculations

if the program completes the flow field and particle trajectory calculations

with no errors, there generally will be no additional errors in the ther-

modynamic calculations. There are temperature limits in the subroutines

used to calculate the pressure of water vapor over liquid water and over

ice. These calculations are performed in subroutines PVW and PVI, re-

spectively. The temperature ranges, shown below, are sufficient for any

anticipated application of the code.

Vapor Pressure over Liquid Water: 223.15 K < T < 323.15 K

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Vapor Pressure over Ice : 213.15 K < T < 273.15 K

8.6 COMMON Blocks and Work Files

In a program of this size,much of the information must be transfered

between subroutines through COMMON statements. Table 8.1 listseach

COMMON block in the program, the general purpose of the variables in

the COMMON block, and the subroutines in which each block is found.

No open COMMON statements are used in LEWICE.

In addition to COMMON blocks, much information ispassed between

subroutines through temporary work files.The work filesand the purpose

of each are shown in Table 8.2. Many of these filesare used in the potential

flow calculations (subroutine $24Y), and will not be described in detail

because littlework was done to modify the potential flow calculations.

8.7 Size of the Code

Because LEWICE combines three complex computer codes into a single

computational algorithm, the code requires a substantial amount of com-

puter memory for both the source code and operation. On the IBM 370

computer used at NASA Lewis, the source code itself requires approxi-

mately 1400 K of memory. The input file requires only 4 K, but 500 K

should be allowed for the output file, especially if a droplet distribution has

been specified. Also, a restart file is generated by the program which will

be the same size as the input file. The work files used in the code require

approximately 150 K of memory. They are erased at the termination of the

run and, therefore, could be placed in a temporary work area.

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Table 8.1 Common Blocks Used in LEWICE

COMMON Block

LABELS Contents:

Variables:

Subroutines:

CNTL Contents:

Variable:

Subroutine:

PSEUDO Contents:

Variables:

Subroutines:

ICECOM Contents:

Variables:

Subroutines:

Description

Parameters to be placed on plots

IDR, VINF, LWCKG, TAMB, PAMB, RH,

MAIN, BORDER

Control parameters used in the plotting

and particle trajectory routines

LOPT, LEQM, IPLOT, LCMB, LCMP

MAIN, TRAJ, IMPLIM, COLLEC, INTIG,

RANGE, MODE, READIN, VELCTY, COMB2I)

x-coordinates of the pseudo surface that havc

been generated

IPSURF, XPS

MAIN, STAG, VEDGE, PSURF, NEW45,

MODE, READIN

Variables used in the thermodynamic and

ice accretion subroutines

X, Y, SEGLEN, SEGLIN, VE, TE, PE,

RA, XK, BETA, TSURF, FFRAC, HTC, RI

QCOND, MDOTC, MDOTE, MDOTRI, MDOTTI,

MDOTT, DICE, VINF, TAMB, PAMB, RH,

DPMM, LWCKG, CPA, CPI, LV, LF, VISC,

PI, NPTS, NTHI, NTLOW, ISTAG

CNSTS, STAG, PSURF, NWPTS, SEGSEC,

ICE, CDYLYR, EBAL, COMPF, COMPT,

NWFOIL, OUTPUT, PLOTD

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Table 8.1 Continued

COMMON Block Description

DROP Contents:

Variables:

Subroutines:

Droplet distribution data

NSI, FLWC, IRS, DPD, EPT

PLOTD, TRAJ, EFFICY

BFLAG Contents:

Variables:

Subroutines:

Potential flow data

IDB, INL, IFL, NL, LIFT, IBMF, ISAV1,

ISAV2, ISAV3, BTITLE, IBT, IBST,

IBTOT, NELTOT, ITRB, INMB, CHORDB,

IBD, LIFTOT, IPRB, IFST, ISEC,

FTITLE, IPVR

$24Y, MAIN1, MAIN3, ASSEMB, ELFORM,

FLOWS, MAFORM, PRNTEL, VXYOFF

COMBO Contents:

Variables:

Subroutines:

Potential flow data

CCL, INCLT, CLT, ALPHA, SUMDS, TLU,

IND, ALPHAO, CNU, SMDSWF, MIO

$24Y, MAIN1, MAIN3, ASSEMB, COMBO,

FLOWS, MAFORM, OFFBOD, VXYOFF

FILEID Contents:

Variables:

Subroutines:

Potential flow data

IFILE1, IFILE2, IFILE3, IFILE4,

IFILE5, IFILE6, IFILE7, IFILE8,

IFILE9, IFILIO, IFILll, IFIL12,

IFIL13, IFIL14, IFIL15, IFIL16,

IFIL17, IFIL18, IFIL19, IFIL20

$24Y, REWYND, FILRS, MAIN1, MAIN3,

SOLVE, ASSEMB, COMBO, ELFORM, FLOWS,

MAFORM, VPROFF, VXYOFF

MDATA Contents:

Variables:

Subroutines:

Potential flow data

ISOL, IOFF, NONU, MBNU, IPRINT, MORE, M

$24Y, MAIN1M MAIN3, ASSEMB

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Table 8.1 Continued

COMMON Block

ROTAT Contents:

Variables:

Subroutines:

ELDATA Contents:

Variables:

Subroutines:

GCOEFS Contents:

Variables:

Subroutines:

COM Contents:

Variables:

Subroutines:

SPACER Contents:

Variables:

Subroutines:

SIGMAS Contents:

Variables:

Subroutines:

GEOMD Contents:

Variables:

Subroutines:

GCFF Contents:

Variables:

Subroutines:

Description

Potential flow data

NROT, ROTRAD

$24Y, ASSEMB, FLOWS, MAFORM

Potential flow data

XO, YO, DS, SA, CA, CURV, DL

MAIN1, ASSEMB, ELFORM, MAFORM

Potential flow data

CD, CF, CG, CI, WF

MAIN1, ASSEMB, ELFORM, MAFORM

Potential flow data

IFILL

MAIN1, MAIN3, FLOWS, VPROFF, VXYOFF

Potential flow data

WKAREA

SOLVE

Potential flow data

CSIG, CK

COMBO, FLOWS, VXOFF

Potential flow data

X, Y, XSAVE, YSAVE

ELFORM, FLOWS, BTITLE

Potential flow data

CD, CF, CG, CI, WF

FLOWS, VXYOFF

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Table 8.1 Continued

COMMON Block Description

ELDD Contents:

Variables:

Subroutines:

Potential flow data

X, Y, DS, SA, CA, CURV, DL

FLOWS, VXYOFF, READIN, VELCTY

OVER Contents:

Variables:

Subroutines:

Potential flow data

V1Y, V2Y, V3Y, V4Y, V5Y, V6Y, V3X,

V4X, VSX, V6XVPROFF

BODY Contents:

Variables:

Subroutines:

Coordinates describing the body

geometry

NPTS, XSH, YSH, X, Y

TRAJ, MODE, READIN, PLTRAJ

BOUND Contents:

Variables:

Subroutines:

Coordinates of the most forward and

aft points of the body geometry and

boundaries for the particle trajectory

calculations

XFRNT, YFRNT, XREAR, YREAR, XSTOP,

YLO, YUP

TRAJ, RELEAS, IMPLIM, INTIG, RANGE,

MODE, READIN

IMP Contents:

Variables:

Subroutines:

Particle impingment data for use in

the collection efficiency calculation

S, SW, YO, IS

TRAJ, IMPLIM, COLLEC, ORDER, INTIG,

RANGE, MODE, READIN

INIT Contents:

Variables:

Initial conditions for particle

release

XIN, YIN, DPM, RL, PITDOT, PIT,

VINF, VXP, VYP, AOAR

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Table 8.1 Continued

COMMON Block Description

Subroutines: TRAJ, RELEAS, IMPLIM, COLLEC, INTIG,

RANGE, DIFFUN, MODE, COMB2D

DIFF Contents:

Variables:

Subroutines:

Variables used in the particle

trajectory equations

Q, AMASS, G, YYI, VISC, CF

TRAJ, DIFFUN

STEP Contents:

Variables:

Subroutines:

Time step and error criteria used

in the integration of the particle

trajectory equations

TIMSTP, EPS

TRAJ, IMPLIM, COLLEC, RANGE

TP15 Contents:

Variables:

Subroutines:

Variables used to calculate the

combination solution of velocity

ABCD, ATOTAL, VC15, RSORTC, NX15

READIN, COMB2D

NUM Contents:

Variables:

Subroutines:

Variables used to calculate the

flow field velocities

N, M, IND, IBTOT, LIFTOT

READIN, VELCTY

GCF Contents:

Variables:

Subroutines:

Parameters used to calculate the

flow field velocities

CD, CF, CG, CI, WF, CSIG, CK, SIG

READIN, VELCTY

FLG Contents:

Subroutines:

Parameters used to calculate the flow

field velocities

READIN, VELCTY

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COMMON Block

VEX Contents:

Subroutines:

Table 8.1 Continued

Description

x- and y-components of the flow

field velocity

VELCTY, COMB2D

Table 8.2 Output and Work Files Used in LEWICE

i 3

File

Number

1,2,4,

7-18,

21

5,6

2O

22

Type Description

Binary

Character

Character

Character

These are work files used in the potential

flow calculations. Since no modifications

were made to $24Y, the contents of these files

have not been examined in detail.

Unit 3 contains the y0 vs. s points for each

droplet diameter. This file is read in

subroutines EFFICY and PLOTD.

These are the read/write defaults to displayinformation on the screen.

This file contains the airfoil coordinates for

all timesteps. The file is read in subroutine

PLOTD to plot the airfoil.

Unit 22 contains the airfoil segment distances

used in the collection efficiency

calculations.

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Table 8.2 Continued

File

Number

24

3O

35

36

45

56

Type

Character

Binary

Character

Character

Character

Character

Description

This is an internal input file for subroutine

TRAJ. It is created from the input on

unit 35. There is no updating of unit 24 for

the second or subsequent timesteps.

This is the main working file for the

program. It contains the current values of

the body coordinates, surface distances,

edge velocities, pressures, etc. for each

segment.

This is the primary input file prepared by

the user. It is used to set up all of the

other internal input files.

This is the restart input file produced by

the program after each timestep. It is

identical to the input file on unit 35,

except that the body coordinates are of the

current ice shape. The icing time

corresponding to the ice shape coordinates

is also included in namelist ICE.

This is the internal input file for the

potential flow code ($24Y). It is formed from

the data input on unit 35.

This is the primary output file for LEWICE.

It contains the printed output from all

portions of the code.

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8.8 Execution Times

When an ice shape is predicted, the largest portion of the execution time is

spent on the particle trajectory calculations. The CPU time required to run

the example cases found in Section 7.0 on the IBM 370 computer are given

in Table 8.3. Also indicated are the total number of particle trajectories

calculated in each, and the average CPU time per trajectory.

Table 8.3 CPU Time for Examples 1-5

Number of

Example CPU Time Trajectories CPU-sec

Number (see) Calculated Trajectory

1 362.52 67 5.41

2 350.80 71 4.90

3 395.01 68 5.81

4 719.30 205 3.51

5 185.50 44 4.22

With these results, the computational time required for a specific icing

condition can be estimated if the speed of another type of computer is

known compared to an IBM 370.

8.9 Getting LEWICE Operational

When LEWICE is transferred to a system other than that at NASA Lewis,

it must first be compiled. A FORTRAN 77 compiler has been used to

compile the version used at NASA Lewis. The graphics commands used

in LEWICE are from a system that is unique to NASA Lewis and will

not be directly applicable to any other system. The name of this graphics

package is GRAPH3D, but most of the commands in LEWICE are from

GRAPH2D, the predecessor of GRAPH3D. Calls to the graphics package

are located in subroutines STAG, PSURF, PLOTD, BORDER, INTIG,

PLTRAJ, and EFFICY. The graphics in LEWICE use only the simplest

commands, and, therefore, modification of the commands should not be

difficult; unfortunately, it will probably be time-consuming.

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I_|st of References

.

.

Ackley, S.F. and Templeton, M.K. UComputer Modeling of Atmo-

spheric Ice Accretion." Cold Regions Research and Engineering Lab-

oratory Report 79-4, 1979.

Lozowski, E.P., Stallabrass, J.R., and Hearty, P.F. _The Icing of an

Unheated Non-Rotating Cylinder in Liquid Water Droplet-Ice Crystal

Clouds." National Research Council of Canada Report LTR-LT-96,

1979.

3. Hankey, W.L. and Kirchner, R. "Ice Accretion of Wing Leading

Edges." AFFDL-TM-85-FXM, 1979.

.

,

.

.

.

.

10.

Cansdale, J.T. and Gent, R.W. UIce Accretion on Aerofoils in Two-

Dimensional Compressible Flow - A Theoretical Model." Royal Air-

craft Establishment Technical Report 82128, 1983.

MacArthur, C.D., Keller,J.L.,and Leurs, J.K. "Mathematical Mod-

eling of Ice Accretion on Aerofoils."AIAA-82-0284, 1982.

Olsen, W., Shaw, R., and Newton, J. "Ice Shapes and the Resulting

Drag Increase for an NACA 0012 Airfoil." NASA Technical Memo-

randum 83556, 1984.

Tribus, M.V., et al. "Analysis of Heat Transfer Over a Small Cylinder

in Icing Conditions on Mount Washington." American Society of

Mechanical Engineers Transactions, Vol. 70, 1949, pp. 871-876.

Messinger, B.L. _Equilibrium Temperature of an Unheated Icing Sur-

face as a Function of Airspeed." Journal of the Aeronautical Sciences,

Vol. 20, No. 1, 1953, pp. 29-42.

Olsen, W. "Close-up Movies of the Icing Process on the Leading Edge

of an Airfoil." NASA Lewis Research Center Movie C-313, 1985.

Hess, J.L. and Smith, A.M.O. "Calculation of Potential Flow About

Arbitrary Bodies." Progress in Aeronautical Sciences, 8:1-138, (D.

Kuchemann, editor). Elmsford, New York, Pergmon Press, 1967.

158

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11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

Harris, C.D. "Two-Dimensional Aerodynamic Characteristics of the

NACA 0012 Airfoil in the Langley 8-Foot Transonic Pressure Tunnel."

NASA TM 81927, April 1981.

Frost, W., Chang, H., Shieh, C., and Kimble, K. "Two- Dimensional

Particle Trajectory Computer Program." Interim Report for Contract

NAS3-22448, 1982.

Chang, H., Frost, W., and Shaw, R.J. "Influence of Multidroplet Size

Distribution on Icing Collection Efficiency." AIAA-83-0110, 1983.

Hobbs, P.V. Ice Physics. Oxford University Press, Ely House, Lon-

don, 1974.

Carlson, D.J. and Haglund, R.F. "Particle Drag and Heat Transfer in

Rocket Nozzles." AIAA Journal, Vol. 2, No. 11, 1964, pp. 1980-1984.

Gear, C.W. "The Automatic Integration of Ordinary Differential

Equations." Comm. ACM 14, 1971, pp. 176-179.

Gear, C.W. "DIFSUB for Solutions of Ordinary Differential Equa-

tions." Comm. ACM 14, 1971, pp. 185-190.

Macklin, W.C. "The Density and Structure of Ice Formed by Accre-

tion." Quarterly Journal of the Royal Meteorological Society, Vol.

88, 1962, pp. 30-50.

Bragg, M.B., Gregorek, G.M., and Shaw, R.J. _An Analytical Ap-

proach to Airfoil Icing." AIAA-81-0403, 1981.

Gent, R.W., Markiewicz, R.H., and Cansdale, J.T. "Further Studies

of Helicopter Rotor Ice Accretion and Protection." Paper No. 54,

Eleventh European Rotorcraft Forum, September 1985.

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Appendix A

DERIVATION OF THE ICING ENERGY EQUATION

In this appendix, the thermodynamic processes that take place during

the formation of an ice accretion are identified and expressed mathemati-

cally to form the icing energy equation. This derivation is similar to that

presented in Reference A-l, except that the equation is applicable to an

arbitrary control volume instead of a control volume situated on the stag-

nation line.

A.1 Definition of the Control Volume

The control volume to be analyzed is located on the surface of the body

and extends from outside the boundary layer to the surface of the body,

as shown in Figure A-1. It encloses a distance along the external surface,

and, for dimensional completeness, extends one unit length in the spanwlse

direction (into the page). The lower boundary of the control volume is

initially on the surface of the clean geometry, and moves outward with the

surface as the ice accretes. Therefore, the control volume is always situated

on either the clean or iced surface, and any accumulated ice is considered

to leave the control volume through the lower boundary. This definition is

important in conduction heat transfer, discussed later in this appendix.

A.2 Mass Balance on an Icing Surface

An evaluation of all mass entering and leaving the control volume is

shown in Figure A-2. A mass balance equation can be formed from these

terms as shown below.

rh, + rhr_. - rh, - rhro., = rh_ (A - 1)

At the stagnation point, there will be no water inflow along the surface

so therefore, m_n = 0.0.

Since the freezing fraction is defined as the proportion of the total mass

of liquid entering the control volume that freezes in the control volume, it

can be expressed by the following equation:

f - m' (A - 2)

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Substituting Equation {A-l) into Equation {Ao2), the water flow out of

the control volume can be expressed as

m,_, = {1- l){m, + m,,.}- m, (A-3)

A.3 Energy Balance on an Icing Surface

The same control volume concept is used to formulate the energy bal-

ance on the icing surface. The First Law of Thermodynamics for a control

volume can be expressed as: energy inflow rate -- energy outflow rate +

energy storage rate.

The modes of energy transfer, illustrated in Figure A-3, are as follows:

Mode of Energy Transfer

1. Impinging Water

2. Water Flow Into Control Volume

3. Evaporation4. Water Flow Out of Control Volume

5. Ice Accumulation Within Control Volume

6. Convection

7. Conduction through the Skin

Energy Flow Rate

rhciw,T

#nr,. iw,.,,.( _- , )

¢n.io,.,,.

rh...,i.,._,.{O

qcAs

qkA8

Using the convention that energy flow into the control volume is positive,

the terms can be summed to yield the general form of the energy equation:

rh, {w.T + mr,. {w,°u.(,-l) -" the i,_,.u. -t- rh.o., iw,.u.

+ rh_ it°,,. + q. As + qk As (A-4)

The evaluation of the terms of the energy equation has been made by

various authors, most notably by Sogin {Reference A-2), Lowzowski {Refer-

ence A-3), and Cansdale and Gent {Reference A-4). The following sections

will evaluate each of the terms of Equation (A-4).

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A.4 Impinging Water

Since droplets are essentially brought to rest when they strike an object,

it is appropriate to use the stagnation enthalpy defined as

v2i.,T = c,.,. (r. - 273.15)+ ®

2(A - 5)

The arbitrary reference for zero enthalpy used in this study is water at

273.15 K. Substituting Equation (A-5), the energy flow rate of the imping-

ing water becomes

r_c iw,T = Trtc Cp,,o

where

m,"" = LWC(Voo)_ (A- 7)

A.5 Water Flow Into the Control Volume

The water flowing into the control volume will be at the surface tem-

perature of the preceding control volume. The enthalpy can therefore be

expressed as

i.,...(__,)= % ....,(,_,) (Tw(,-,) - 273.15)

where (i-l) denotes that the specific heat and temperature are evaluated at

the conditions of the proceding control volume. The runback water energy

flow rate into the control volume can therefore he expressed as

rh,,. {.,,.,(;-1)= m,;. c_ ..... (,_,) (T,,,,(__,)- 273.15) (A-9)

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A.6 Evaporation

The rate of energy transfer from the surface because of evaporation is

given by

• .[ ]rh, su.,u, -- m, c_,,.o..(T_,r - 273.15) -}- L, As (A - 10)

where rne"" is the evaporative mass transfer flux and L, is the latent heat of

vaporization.

The mass transfer rate is analogous to the convective heat transfer rate

and can be written as

.H

m e =gAB (A-11)

where g is the mass transfer coeffcient and AB is the evaporative driving

potential. The mass transfer coefficient, g, can be evaluated using the

analogy to heat transfer given by the following equation found in ReferenceA-5:

hc ( Pr _ "_7g = cp--_ \So/

(A- 12)

In Equation (A-12), Pr is the Prandtl number and Sc is the Schmidt num-

ber.

The mass transfer driving potential is analogous to the temperature

difference in the convective heat transfer equation. In the case of evapora-

tion, the driving potential is a vapor concentration difference instead of a

temperature difference. The equation used in this study is similar to that

derived by Sogin (Reference A-2), and given as

AB = (A- 13)

(1/.622)P,/T, - P,.,,,,/T,_,,

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This term accounts for compressibility effects, as does the term derived

by Cansdale in Reference A-4.

When the water droplets freeze on impact (f = 1.0), there is no liquid

water on the surface to be evaporated; however, water vapor can still leave

the surface through sublimation. In this case, Equations (A-10), (A-11),

(A-12), and (A-13) are still used to determine the rate of energy transfer

from the surface, except that the latent heat of sublimation, L,, is used in

Equation (A-10) instead of the latent heat of vaporization, Lu.

A.7 Water Flow Out of the Control Volume

The water flowing out of the control volume will be at the surface tem-

perature of the control volume, allowing the enthalpy to be expressed as

i_,°ur(i) -: c_ ..... (0 -- (T"ffir¢d) -- 273.15) (A -- 14)

where (i) denotes that the specific heat is to be evaluated at the surface

temperature of the control volume being analyzed. Using Equation CA-3),

the runback water energy flow rate can be expressed as

rh, o,,, i,,,,°,,,(,)- [(1-f)(rh,+rh,,,,)-_h.] cj,,,,,.,,,,o (T.,,,(,)-273.15) (A- 15)

A.8 Ice Accumulation Leaving the Control Volume

As previously discussed, the control volume remains on the surface of the

geometry as the ice accumulates within the control volume.

From the definition of the freezing fraction, Equation (A-2), the freezing

rate is

The enthalpy of ice referenced to water at 273.15 K is

(A-16)

ii,°., : cp, .... (Tw - 273.15) - L! (A- 17)

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Combining Equations (A-16) and (A-17), the rate of energy leaving the

control volume in the accumulated ice can be expressed as

fn, i,.°u, = f (The + Th,,.) [%, .... (T_, - 273.15) - LI] (A- 18)

A.9 Net Convective Heat Flux

The local value of the aerodynamically induced heat flow to or from

the outer boundary of the control volume is determined by the convective

cooling and kinetic heating of the surface. The net convective heat flow

can therefore be defined by the following equation:

qo/_ = ho(T.., - To.) A_ (A - 19)

In this equation, T0_, is the surface temperature and 2",, is the adiabatic

wall temperature. The adiabatic wall temperature is given by

v:(A- 20)

To_ = T_ + r_ 2 %.

where T, and V, are the temperature and velocity at the edge of the bound-

ary layer, respectively, and rc is the recovery factor. The local temperature

is calculated from the pressure coefficients calculated by the potential flow

code using the isentropic relationships. Substituting Equation (A-20) into

Equation (A-19), the expression for the convective heat flow rate becomes

qcas= ho(T..,-T.r_ V,_.

c-_) As (A - 21)

The heat transfer coefficient is calculated using the integral boundary

method described in Appendix B.

A.10 Conduction From the Airfoil Surface

When the cloud is first encountered, a temperature difference will exist

between the wetted surface and the inner structure of the airfoil. Prior to

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entering the cloud, this inner structure is assumed to be at an equilibrium

temperature. The evaluation of the resulting conductive heat flow rate is

dependent on knowing the thermal conductivity and detailed geometry of

the inner structure of the airfoil.

After a layer of ice forms on an unheated surface, the temperature of

the skin should again reach an equilibrium temperature. Since ice is an

insulator, any heat transfer through the skin will not affect the growth of

the ice accretion at the air/ice interface.

In a thermal deicing system, an ice layer is allowed to form and heat is

then applied at the ice/skin interface. The effect of this heat is to melt the

ice attached directly to the surface, thereby allowing the ice to shed due

to the aerodynamic forces acting on the ice accretion. Currently, LEWICE

is not capable of analyzing this deicing phenomenon because a thermal

analysis would be required not only at the air/ice interface but also at the

ice/surface interface. A complete description of the current capability to

model a thermal deicing system is given in Reference A-6.

A thermal anti-icing system differs from a deicing system in that suffi-

cient heat is applied to prevent any ice from forming. The formulation of

the icing energy equation in LEWICE should be applied to thermal anti-

icing systems only to determine the minimum heating requirements to keep

ice from forming on the surface. The heat flux from the skin is specified as

a function of s and is assumed to be from the inner control volume bound-

ary. On the first timestep, this boundary is the uniced surface. If the heat

input is not sufficient to keep ice from forming, the heat input on the second

timestep would be assumed to come from the iced surface and incorrectly

neglects the thermal conductivity of ice and the effect of the varying ice

thickness on the surface. An example of the application of the code to a

thermal anti-icing system is discussed in Section ?.5.

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The energy terms can now be summed to form the complete energy

balance for an icing surface used in LEWICE. This equation is as follows:

[(I - f)Crh, + Th,,,,) -- rh,] c,,.,,., (T_, - 273.15)4-

)'(rhc- )'h,.,) [c)),,,., (T). - 273.18) - L/]+

h, [T,_, - T, 2cp. J

The solution of Equation (A=22) is presented in Section 4.3.2.

(A - 22)

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List of References

1. Ruff, G.A. "Analysis and Verification of the king Scaling Equations."

AEDC-TR-85-30 Vol. 1 (Revised), 1985.

2. Sogin, H.H. "A Design Manual for Thermal Anti-Icing Systems."

Wright Air Development Center (WADC) Technical Report 54-313,

1954.

3. Lozowski, E.P., Stallabrass, J.R., and Hearty, P.F. _The Icing of an

Unheated Non-Rotating Cylinder in Liquid Water Droplet-Ice Crystal

Clouds." National Research Council of Canada (NRC) Report LTR-

LT-96, 1979.

4. Cansdale, J.T. and Gent, R.W. "Ice Accretion on Aerofoils in Two-

Dimensional Compressible Flow - A Theoretical Model." Royal Air-

craft Establishment Technical Report 82128, 1983.

5. Kreith, F. Principles of Heat Transfer. Harper & Row, Publishers,

Inc., New York, 1973.

6. Leffel, K.L. "A Numerical and Experimental Investigation of Elec-

trothermal Aircraft Deicing." NASA CR 175024, 1986.

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0

/

o//°

_/ o

/0\/ \

o

o

CLEAN AIRFOIl./

ICE SURFACE

Figure A-l: Identification of a control volume.

2.

\\ 3.

\ S.

\

IFIPINGING WATER Mc

EVAPORATION _e

WATERFLOW OUT OF CV MrOUT

WATER FLOW INTO CV t_rl x

ICE ACCUMULATION _iLEAVING THE CV

Figure A-2: Mass balance for a control volume.

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i //'_%

I.

/// 3.

q.

5,

6,

7.

II_INGING WATER _Iciw,T

£YAPO_TIO_ _eiv,suR

_/Aff.RFLO_OUTOF ¢V _rouTiW,su_

k_TEaFLOWIMTOCV _rxNiw,suR

ICE ACCUPLATION _i i i ,SURLEAVINGTHECV

CONVECTION qc As

CONI_I"I ON qK As

_C:iw,T + " . +qKAS " . + ' . +_i i +qcSsturin IWoSUR = Helv,stm 14rOUTIM,SUm I,SUR

Figure A-3: Energy balance for a control volume.

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APPENDIX B

INTEGRAL BOUNDARY LAYER METHOD ON AN ICED

SURFACE

As described in the text, the evaluation of the boundary layer character-

istics using a complete Navier-Stokes solver would be too time-consuming

to be practical in an interactive program such as LEWICE. An integral

boundary layer solution was therefore developed to account for surface

roughness and variable velocity in the calculation of the convective heat

transfer coefficient. The original algorithm was developed by UDRI, but

was modified in the current version of LEWICE.

B.1 Characterization of the Ice Surface Roughness

The integral boundary layer method to be applied in LEWICE is re-

quired not only to determine the convective heat transfer coefficient on the

iced surface in the laminar and turbulent regions, but also to determine the

location of the transition from laminar to turbulent flow (transition point).

The transition to turbulent flow is caused primarily by the surface rough-

ness of the iced surface which acts to trip the boundary layer from laminar

to turbulent flow. Also, once turbulent, the surface roughness elements

enhance the convective heat transfer coefficient by 1) increasing the skin

friction coefficient and 2) increasing the effective surface area from which

heat transfer takes place.

A representative surface of an actual ice accretion is shown in profile in

Figure B-1. The size and shape of the surface roughness elements found on

typical ice accretions are functions of the atmospheric and meteorological

conditions at which the ice is formed. Unfortunately, there is insufficient

data to characterize the size and shape of the surface roughness as a func-

tion of those conditions. Also, the complex roughness patterns found on

typical glaze ice accretions are beyond the analysis capability of an integral

boundary layer method. Therefore, an alternate method to characterize

the surface roughness is required.

Analysis of rough surfaces has been performed by numerous investiga-

tors, one of the earliest and most well-known being Nikuradse (Reference

B-l). These experiments dealt primarily with turbulent flow in pipes that

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were artificially roughened with uniform grains of sand. Schlichting (Ref-

erence B-2) introduced the concept of equivalent sand-grain roughness as

a means of characterizing other types of roughness elements by referring

to the equivalent net effect produced by Nikuradse's experiments. In this

application, the irregular roughnes8 elements of an iced surface are repre-

sented by a value of equivalent sand-grain roughness height, k0, as shown

in Figure B-2. This value is specified by the user and is constant during the

calculation of a given icing condition. The value of ko should be changed as

a function of the atmospheric and meteorological parameters of the icing

condition using the guidelines discussed in the text.

B.2 Calculation of the Boundary Layer Characteristics

Determination of the Transition Location

The evaluation of the boundary layer is begun at the stagnation point

(s = 0.0). The calculations are initiated by determining the location of the

transition for laminar to turbulent flow, i.e., the transition point. The crite-

ria for transition, developed by Von Doenhoff (Reference B-3), assumes that

the flow will become turbulent when the local roughness Reynolds number

is greater than 600. The empirical criteria, based on data obtained using

sand-grain type roughness elements, are therefore given by the following

equation

R,, = k. > 600 (B - )V

where k0 is the equivalent sand-grain roughness height representing the

actual ice surface roughness. The velocity at y -- k,, designated V_, (Figure

B-2) must be determined to evaluate the local roughness Reynolds number.

The following is the method used to determine Irk, found in Equation (B-l).

Assume that the laminar velocity profile can be represented by a 4th

order polynomial of the form

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where 6 is the boundary layer thickness, and V, and y are defined in Figure

B-2. This assumption is known as the Pohlhausen approximation (Refer-

ence B-4, pp. 310-311). By applying the following boundary conditions at

y=O:

a=V 1 ap dV. (B-3a)ay, ; _ -v"i:

lira --a"V = 0 n = 1, 2, 3, ... (B- 3b)v-.oo ay"

it can be shown that the expression for V/V, resulting from Equation (B-2)

is

V(y)- [2(y/6) - 2(y/6)' + 2(y/6)'] + 1/6 A (y/,_) C1 - y16) 3 (B 4)

v,

where

A= 62/u dVe (B - 5)

If we let y = ko in Equation (B-4), the velocity at y = ko can be written

as follows:

Vk =[2(k,/6) - 2(k,/6)' + (k./6)'] + 1/6 A (k./6)(1 - k./6)' (B-6)v,

To apply this equation, the boundary layer thickness, 6, must be evaluated.

The laminar momentum thickness, St, is defined in Reference B-4, p.

244, as

8,=fo '_V" (1 -- FY--_)dyf. (B- 7)

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Substituting Equation (B-4) into Equation (B-7) and integrating from

y = 0 to y = 6, it can be shown that 6 is related to the laminar momentum

thickness by the following approximation:

6 = s.s 0_ (B - 8)

From the integral momentum equation, the laminar momentum thick-

ness can be evaluated using Thwaites formula (Reference B-4, p. 315) which

is given by the following equation:

.45u fo° V6d °

If it is assumed that the velocity at the edge of the boundary layer, V,,

is the surface velocity calculated by the potential flow equations, Equation

(B-9) can be numerically evaluated to determine 0t for each segment on

the body. Equations (B-6) and (B-8) can then be applied to determine Vk

as a function of s, and, therefore, Equation (B-l) can be evaluated along

the surface to determine whether the flow has transitioned from laminar to

turbulent flow.

Laminar Convective Heat Transfer Coefficient

If the boundary layer is found to be laminar at a surface distance, s,

the convective heat transfer coefficient for flow over a constant temperature

body of arbitrary shape is calculated using an equation developed by Smith

and Spaulding and described in Reference B-4, pp. 327-329. This equation

is given as

t_,(_)= .2o6_ v,-'." v,'."d_ (B-IO)

where _ is the thermal conductivity of air.

Turbulent Convective Heat Transfer Coefficient

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If, upon evaluating Equation (B-l), it is found that the boundary layer

is turbulent, Equations (B-7)-(B-10) are not applicable, and an alternatemethod to determine the convective heat transfer coefficient must be de-

veloped. Using a technique outlined in Reference B-5, an overall Stanton

number can be developed using the thermal and momentum laws of the

wall for fully rough flow. This equation is given in Reference 13-5, p. 132

as

st = I/2 (B- 11)P,,+ O/st.)

The terms of this equation that must be evaluated are the skin friction

coefficient, c/, and the roughness Stanton number, Stk. The experimental

data for air (Reference B-6) suggest that the turbulent Prandtl number,

Pn, is approximately constant and equal to 0.9.

Assuming for now that the values of c! and Stk are known, the turbu-

lent heat transfer coefficient is calculated using Equation (B-11) and the

definition of the Stanton number. Therefore,

h, Cs) = S'tpV,cj, = [ c!/2 ]Pr, + V/_(1/,S'tk) 1 .af/',cp

(B- 12)

The expressions for the skin friction coefficient and the roughness Stan-

ton number are now developed.

Skin Friction Coefficient

If the boundary layer has been found to be turbulent, i.e., the roughness

Reynolds number is greater than 600.0, the surface can be considered to

be fully rough (Reference B-5, p. 186). A basic characteristic of the fully

rough surface is that the skin friction coefficient, el, is independent of the

Reynolds number. In this region, the pressure drag on individual roughness

elements dominates and viscosity is no longer a significant variable. With

this assumption, an expression for the skin friction coefficient can be devel-

oped from the momentum law of the wall for fully rough flow (Reference

B-5, pp. 186-188) as follows

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c! .41 ] _-- __ l,,( se4.00 , J2 ."'_ k, +2.568)

(B- 13)

where 0t is the turbulent momentum thickness and ko is the equivalent sand-

grain roughness height. (This equation was derived in a manner similar

to Equation 10-45 in Reference B-5 except that Equation 10-43 was not

simplified.)

The turbulent momentum thickness is evaluated using the momentum

integral equation in a manner similar to that for the laminar momentum

thickness. The equation for 0t is given in Reference B-5, p. 175 as

[.0156 Vf "s6 ] .s= Lv,.. /o" d. (B- 14)

Since the turbulent boundary layer is proceeded by a laminar boundary

layer, the numerical integration of Equation (]3- 14) is begun at 8 =str

instead of s = 0.0. The laminar momentum thickness already existing at

s : .st, must then be added. Equation (B-14) can therefore be written as

01 0/; ]-0tea)= _ ,. V_'Sed8 + O,(n..)(B-15)

where 0_ is evaluated using Equation (B-O) and Ve is the surface velocity

calculated by the potential flow code.

Roughness Stanton Number

The roughness Stanton number is developed from the thermal law of

the wall for fully rough flow, and is given in Reference B-5, p. 231 by an

equation of the form

Sit : C Pr -'44 (B - 16)

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where V, is the shear velocity. In Equation (]3-16), C is a constant that

must be determined from experimental data and is a function of the type

of roughness. Data for a rough surface composed of closely-packed spheres

yields a value of C = 1.0 (Reference ]3-6). Setting the Prandtl number,

Pr, equal to 0.72 and substituting the values for C and Pr into Equation

(B-16), the expression for Stk becomes

(B- 17)

The shear velocity, u,, is evaluated using the equation from Reference B-5,

p. 187.

v,= Vf_-I/2 (B- 18)v,

In this equation, c! is determined from Equation (B-13).

B.3 Method of Solution

To correctly apply the equations previously discussed, the integration

procedure should be identified. As discussed in the text, the geometry is

represented by a set of Cartesian coordinates (nodes) connected by straight

line segments, as shown in Figure B-3. The stagnation point is designated

s = 0.0, and will always fall on a nodel 1 point. The s values used in the

integration correspond to the midpoint of each of the body segments. The

calculation of the boundary layer characteristics is begun by evaluating

Equations (B-6), (B-8), and (B-9) for s = 0.0 to s = 81. The transition

criteria, Equation (B-l), is then applied, and, if the flow is found to be

turbulent at this point, it is assumed to be turbulent at each segment

downstream. Equations (B-13), (B-15), (B-l?), (B-18), (B-11), and (B-12)

are applied to calculate h_ if the boundary layer is turbulent. If the flow is

laminar, Equation B-10 is used to calculate hc and the turbulence criteria

is checked at the next segment. This procedure is then repeated for the

lower surface.

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B.4 Comparison with Experimental Data

The results of the integral boundary layer method described in the pre-

vious sections have been compared to experimental convective heat transfer

data collected by Achenbach (Reference ]3-7). The current method was also

compared to an integral boundary layer method developed by Makkonen

(Reference B-S).

An excellent discussion of the analytical method developed by Makko-

nen and the comparisons to experimental data can be found in Reference

B-8. The work by Makkonen also includes a discussion about the applica-

bility of an integral boundary layer method to the calculation of convective

heat transfer characteristics over an ice accretion shape. Therefore, a de-

scription of the experimental data and detailed analysis of the results will

not be presented in this appendix. Instead, the results of the integral

boundary layer method described in this appendix will only be compared

to the results in Reference B-8 and the general trends identified.

The experimental measurements were made on a 15-cm diameter cylin-

der roughened with grains of sand at various Reynolds numbers. The rough-

ness element height, k, is 0.9 mm and the equivalent sand grain roughness

height, k°, is 1.35 ram. The method developed by Makkonen uses both

the maximum probable roughness height and the equivalent sand grain

roughness height. The method described in this appendix uses only the

equivalent sand grain roughness. Figure B-4 shows a comparison of the

analytical results of LEWICE (with ko = 1.35 mm) and Makkonen to the

experimental results. At a Reynolds number of 4.8 x 104, the method of

LEWICE shows a transition at an angle of approximately 50 °, while no

transition is predicted by Makkonen's results or in the experimental data.

Similar transition locations and location of the maximum heat transfer co-

efficient are predicted by both analytical methods for Reynold's numbers

of 2.8 x 10 s and 8.8 x 10 s. However, the magnitude of the maximum heat

transfer coefficient is over-predicted by the method used in LEWICE.

Since the current method uses only a single roughness parameter, there

is some question whether the maximum probable roughness or the equiva-

lent sand grain roughness height should be used in comparisons with exper-

imental data. A comparison of the analytical and experimental results with

k0 = 0.9 mm in LEWICE is shown in Figure B-5. These results compare

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more favorably with the method of Makkonen and with experimental data

than those in Figure B-4, but still over-predict the maximum value of the

convective heat transfer coefficient.

Measurements of convective heat transfer have also been made on simu-

lated wooden ice accretion shapes roughened with grains of sand (Reference

B-9). Figures B-6a, b, c, and d show the comparisons of the values cal-

culated by LEWICE with experimental data for 2, 5, and 15 rain glaze

ice accretions. In these cases, the maximum probable roughness height of

0.00033 m was used in the calculations. These results show that the pre-

dicted values of hc generally compare well with experiment in the leading

edge region where much of the accretion process will take place.

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Appendix B

List of References

1. Nikuradse, J., Forsh. Arb. Ing.-Wes. No. 361, 1933.

2. Schlichting, H., Ing. Arch.. Vol. 7, 1936, pp. 1-34.

3. Von Doenhoff, A.E. and Horton, E.A. _Low-Speed Experimental

Investigation of the Effect of Sandpaper Type of Roughness on

Boundary-Layer Transition." NACA TN 3858, 1956.

4. White, F.M., Viscous Fluid Flow. McGraw-Hill, Inc, 1974.

5. Kays, W.M. and Crawford, M.E., Convective Heat and Mass Trans-

fer.2nd Edition, MacGraw-HUl Book Company, New York, 1980.

6. Pimenta, M.M., Moffat, R.J., and Kays, W.M. Report No. HMT-

21, Department ofMechanical Engineering, Stanford University,May

1975.

7. Achenbach, E. "The Effectof Surface Roughness on the Heat Transfer

from a Circular Cylinder to the Cross Flow of Air." "International

Journal of Heat and Mass Transfer.",Vol. 20, 1977, pp. 359-369.

8. Makkonen, L. "Heat Transfer and Icing of a Rough Cylinder." "Cold

Regions Science and Technology." Vol. 10, 1985, pp. 105-116.

9. Van Fossen, G.J., Simnoneau, R.J., Olsen, W.A., and Shaw, R.J.

"Heat Transfer Distributions Around Nominal Ice Accretion Shapes

Formed on a Cylinder in the NASA Lewis Icing Research Tunnel."

NASA TM 83557, January 1984.

180

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y_6//

BOUNDARYLAYER--\ //

\ /1 S.\\ //r SURFACE k

\ / I ROUGHNESS

/" [

•,y // d./_"

I'/,,./., - ',,/ /---...__ X--ICE

Figure B-1" Identification of the boundary layer terms usedin the integral boundary layer method.

//

//

//

/!

Figure B-2: Identification of the computational surface beingevaluated by the integral boundary layer method.

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+y

STAGNATIONPOINT

(S " 0.0) -'-....

NODES/1%

I/ _ %,,/ I "

LS 1

+X

Figure B-3: Analytical representation of a typical geometry.

10 I I I

-- LEWICE, xs = 0.00135 M

------ RAKKONEN(REF. B-8)

0 EXPERIRENT (REF. B-7)

I I I I I

RE

8.8 x 105

Q-

0 //

o //

//

/

/

/

/

/

/

/

/

/ o/

2.8 x 105

o 0 o

oo

o

q,8 x 10q o

oo

I I I I

0 10 20 _0 qO

0 0 "" "_ _

0 0 0I l I I

50 60 70 80 90

AN6LE, PEG

FigureB-4: Comparison of caluclated and experimental corrective

heat transfer characteristics,LEWICE k, -- 0.00135m.

182

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10 l l I

LEgICE, Ks = O.O00S M

I_KKONEN (REF. B-8)

EXPER]FENT (REF. B-7)

I i ! i I

RE

8.8 x 105

z

q 0 /

0

//

//

o/

/

o o o o

2.8 x 105

0 00

t I l I I I

0

q.8 x 10q

o o

0 10 20 30 qO 50 60 70

ANGLE, DEG

o o o

80 90

Figure B-5: Comparison of calculated and experimental corrective

heat transfer characteristics, LEWICE k, = O.000gm.

183

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8

1500

i350

1200

1050

I00

75O

600

45O

300

150

g

0 EXPERIMENT (REF. B-9)

-- r3LCULATED

I

0 •

/I l ,, I I I I_.

SURFACE DISTANCE. M

1D. IO

a. Two minute glaze ice shape.

Figure B-6: Comparison of calcuiated and experimental heat--

transfer coefficients on simulated glaze and rime ice shapes.

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i500 --

1360

_, 1200

a_

= 1050

w

900 -

750 --

bOO --

450 _

3OO

150

-°2:1o -1,60 -1.26 -0o6_

EXPERIMENT(REF. B-9)CALCULATED

I I I I-O.q2 0,00 O,q'2 O,Oq- 1,2& 1.68 2.10

s/c

b. Five min glaze ice shape.

Figure B-6: continued

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1600

1350

O0 °

I I I-O.&_ 0.00 0.6_

s/c

0 EXPERIRENT(REF B-91

CALCULATED

0

D

0 0

I JL.2B 1.92 2,5& 3.20

c. Fifteen rain glaze ice shape.

Figure B-6: continued

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z

u

wm_

M

EXPERIME.NT (REF. B-9')

CALCULATED

I I I

0

-0.80 -0._ 0,00

0

0

0

IO,q'_ 0,88 1,32 1.76 2.20

sic

d. Fifteen min rime ice shape.

Figure B-6: Concluded

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APPENDIX C

FLOW FIELD CORRECTIONS

As discussed in the text, there are two types of flow field corrections

that are applied in LEWICE to allow more accurate particle trajectory

calculations. The first correction is made to avoid errors that occur in the

flow field close to the surface because the geometry is represented by discrete

points connected by line segments instead of a smooth curve. These are

called discretization errors. The second correction is made to avoid errors

caused by convoluted ice shapes. Both of these corrections are performed by

producing an imaginary or pseudo-surface which is used in the calculations

instead of the actual ice surface. The corrections are described in the

following sections.

C.1 Correction for Discretization Errors Near the Body

The potential flow computer program used in this study has a relatively

large discretization error very close to the body. As shown in Figure Col,

taken from Reference C-1, the longitudinal and vertical velocities around

the leading edge of the Joukowski airfoil are very irregular close to the airfoil

but become smoother as A_ is increased. (In Figure C-l, A_ is equivalent to

the DSHIFT parameter in LEWICE). The velocity is computed for different

constant values of separation distance from the body, as illustrated in the

insert. Note the large peaks or oscillations in the flow field velocity near

the surface.

Figure C-2 illustrates the trajectories of three different particles released

at very small separation distances, Y0, upstream of the body. Note that

the upper particle turns near the nose and flows backward, reverses direc-

tion again, and flows around the body. The initial intermediate positioned

particle trajectory crosses the lower particle trajectory near the body. It

approaches very close to the surface somewhat downstream of the nose,

and then departs off into the free-stream without impinging on the body.

Finally, the lower particle trajectory impinges on the body. These erratic

trajectories are caused by the strong perturbations in the flow field near

the body.

To overcome the effect of the discretization error near the body, an

artificial impingement surface is generated by the computer program. This

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surface is achieved by displacing the surface of the body a small increment

DSHIFT in the upstream x direction. To generate the pseudo-impingement

surface, the x-coordinates are increased by the quantity DSHIFT times

the cosine of the segment angle while the y-coordinates remain constant.

The resulting pseudo-impingement surface is displaced outward into the

freestream as shown in Figure C-3. The value of DSHIFT is input by the

user in namelist TRAJ1. Commonly used values between .2 to .6 percent

of the chord length encompass the major area of uncertainty in the flow

field.

The pseudo-impingement surface is used only for particle impingement

calculations and does not influence the potential flow calculations. The

pseudo-impingement surface is discarded once the particle trajectory calcu-

lations are completed and is not present when a new ice surface is formed.

C.2 Correction for Multiple Calculated Stagnation Points

Glaze ice accretions are often characterized by the formation of two

horns, as shown in Figure C-4a. The calculation of the flow field around

these typical glaze ice shapes produces undesirable results such as multiple

calculated stagnation points (surface velocity = 0.0). An example of such a

calculation is shown in Figure C-4b. When more than one stagnation point

is calculated, errors occur in the particle trajectory and thermodynamic

portions of the code, causing an abnormal termination. Since the Douglas

potential flow solution is the most feasible method for use in this code, a

method to obtain a sufficiently accurate flow field solution is required when

this situation occurs.

Before the development of computer codes capable of applying the

Navier-Stokes equations to the calculation of flow characteristics in recir-

culation zones, the potential flow codes available had a problem similar to

that in this application. One solution was to replace the boundary of the

separation/reattachment zone with a pseudo-surface, as shown in Figure

C-5. A similar approach is used in this application to smooth the groove

found at the stagnation point of many ice accretions.

Determination of the Locations of Stagnation Points

The location of the stagnation point(s) is determined in subroutine

STAG by checking the non-dimensional edge velocities calculated by $24Y

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(VT) for a change in sign. These velocities will be negative on the lower

surface and positive on the upper surface. The velocity on each segment is

checked, and the number of each segment at which the sign of VT changes

is stored as a stagnation point. If more thaa one sign reversal is found,

it is assumed that the flow field is inaccurate, and the user will be given

the option of selecting one of the calculated stagnation points to use in

the remaining calculations, or to form a pseudo-eurface over the calculated

stagnation points.

The algorithm to form the pseudo-surface is located in subroutine

PSURF. The computer prompts and responses used to form the surface

can be found in Example 2 of Chapter 7. The purpose of the remainder of

this appendix is to demonstrate the accuracy of this method by comparing

experimental data to surface velocity profiles calculated using a pseudo-

surface. The geometries used for these comparisons are simulated 2- and

5-min glaze ice accretions and a 15-min rime ice accretion. These ice shapes

are made of wood and simulate actual ice accretions formed on a cylinder.

The surface velocity measurements were obtained from surface pressure

data for each of the geometries.

Recall that Figure C-4a shows a 5-rain glaze ice accretion for which two

stagnation points were calculated. The corresponding calculated surface

velocity profile is shown in Figure C-4b. A pseudo-surface, shown in Fig-

ure C-6a, was placed over the glaze accretion, and the resulting calculated

surface velocity compared to experimental data. Note that the calculated

velocity profile now has only one stagnation point, and that the calculated

and experimental velocities compare very well near the stagnation point.

Additional applications of the pseudo-surface technique are shown in Fig-

ures C-6b and c. In all cases, the presence of the pseudo-surface produced

smoother velocity profiles which more closely matched experimental results.

This method, while capable of improving the accuracy of the flow field

solution, is an approximation to the true solution and must be treated as

such. For example, Figures C-Ta and b show a 15-min glaze ice accretion

and the corresponding calculated surface velocity. In this case, ten stag-

nation points were calculated. A pseudo-surface, shown in Figure C-Sa,

was placed over the glaze ice accretion, and the calculations were repeated.

As shown in Figure C-8b, the calculated velocity profile is much smoother

than that for the actual ice shape, and the velocity in the groove is slightly

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over-predicted. While this solution would allow the calculation of the iceaccretion to continue, it illustrates that the pseudo-surface technique can

produce a very rough approximation to the actual flow field.

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Appendix C

List of References

1. Frost, W., Chong, H., Shieh, C., and Kimble, K. "Two-Dimensional

Particle Trajectory Computer Program." Interim Report for Contract

NAS3-2244B, 1982.

192

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ORIGINAL PAGE IS

OF POOR QUALITY

8

>-

8

>:

1.20

.83

.45

,O8

I I I I I

A_" = CONSTANTSEPARATION

DISTMCE FROMTHE BODY/'-/

//

/

-.3o I I I I I-.08 -.05 -.03 0 .03 .05 .08

SURFACE DISTANCE, s/_ c

C-1: Discretizationerror in the flow fieldnear the nose of the Joukowski airfoil•

193

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.53

.so,

w-

_ .i17

/

/

• 115 I-.21 -. 16

/-PARTICLE TRAJECTORIES/ / / _-osos5

/ _ "5050

PSEUDO-IRPINGERENTSURFACE_./ _. _..,,_

I I I I _-. 10 -.05 .01 .07 .12

SURFACEDISTANCE, s/J_c x 10-1

C-2: Discretization error in the flow field near the nose of the upper body

of a two-dimensional inlet.

PSEUDO-IRP l NGERENTSURFACE"j

C-3: Illustration of the pseudo-impingement surface.

194

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_-- GROOVE AT THESTAGNATION POINT

\\

\\

\

(a) FIVE RINUTE GLAZE ICE ACCRETION WITH GLAZE HORNS.

250

22S

200

175

tSO

125

lO0

F5

50

0-.15

I-.IZ

I I-.09

i II

-.06 -.03 0.00 0.03

-- CALCULATED STAGNATION

POINTS

SURFACE D[STANCEo M

IO,LZ

i0,15

(b) MULTIPLE CALCULATED STAGNATION POINTS FOR A 5 RINUTE GLAZE ICE SHAPE

C-4: Simulated fiverain glaze ice accretion on a cylinder and the corresponding

calculated surface velocity profile.

195

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FLOW RE-ATTACHRENT

_\_\.__.__ SEPARATED FLOW ZONE

\_'.._GLAZE ICE ACCRETION

PSEUDO-SURFACE_

\

C-5: Example of the application of the pseudo-surface technique on a recirculation zone.

196

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PSEUIX)-SURFACE ---_

\

't\'(

250 --

225 --

200 --

[75 --

t50 --

t2S --

tOO --

75 --

50 --

25 --

o I-.15 -.12

Oo

I-.07 -.06 -.03 0.00 0.03

SURFACE DISTANCE, M

o EXPERIRENT

CALCULATED

I IO.t2 0.15

a. Simulated five min glaze ice shape

C-6: Comparison of experimental surface velocities on simulated ice shapes

to those callculated for the ice shape with pseudo-surface.

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PSEUDO-SURFACE

\

\\\

2°°I180

t60

1 ',t-O

|20 --

I00 --

_ 80-

6O

'tO

2O

0-o10 -.08 -.Oh -.0_

0

0 0

o 0

-.02 O.OO 0.02

SURFACE DISTANCE, e_

0 EXPER[I'ENT

CALCULATED

0 • O"l- O.O& 0.0e

I0,I0

b. Simulated two min glaze ice shape

C-6: continued

198

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PSEUDO-SURFACE -- D

m

>_

150 --

135 --

120 --

LOS --

90 --

?S --

60 --

q'5 --

30 --

15 --

0-o|5

I-.IZ

o EXPERINENT

CALCULATED

I I I ] I I-o07 -,06 -,03 0,00 0,03 0,06 0.09

SURFACE DISTANCE. H

I IO,L2 0,15

c. Simulated fifteen min rime ice shape

C-6: Concluded

199

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ORIGINAL PAGE IS

OF POOR QUALITY

f IO.Ol

a. Locations of the multiple calculated stagnation points

C-7: Simulated fifteen min glaze ice accretion on a cylinder.

200

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ORIGINAL PAGE |S

OF. POOR QUALITY

3OO

270

2_FO

2)0

180

150

120

90 --

60 --

30 --

D-.2(I

I-.16 -.12 - . ()El -oOq- 0.0() I],0_ 0.08 0.)2 0.16

SURFACE DISTANCE, M

IO._'N

b. Calculated surface velocity over the ice shapeC-7: Concluded.

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ORIGINAL PAGE L_

OF. POOR QUALI'[_r

O.O&O fOoO'HI

PSEUDO-SURFACE

I f I ....

-.O6O -.Oq I -,Q3& -_ -.012 o. --

/ / '°

-.01-11 --

-.O&O

I fO.Od

C-8a: Application of the pseudo-surface technique on a simulated

fifteen min glaze ice accretion.

202

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ORI(_INAE PAGE IS

OF POOR QUALITY

>-

,....,>

350 --

315 -

2_-5 --

_?) (| --

I/5 --

ILtO --

I O5 --

?0-

35 ,--

0-.ZO

O EXPER IREttT

CALCULATED

OOO O00 O )0 000 000

J-.16 -.12 -,OH -.O_t - 0.00 O.Oq" O,(18 0.12 0.16

IO,2Q

SURFACE DISTANCE° M

C-8b: Calculated surface velocity over ice shape with pseudo-surface.

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APPENDIX D

COMPLETE INPUT TO THE POTENTIAL FLOW CODE

($24Y)

As noted in Section 5.1, the input to the potential flow code was simpli-

fied for use in LEWICE. Many of the generalities in S24Y are not applicable

to LEWICE, and, therefore, are set to default values in the program (SUB-

ROUTINE SETUP). SUBROUTINE SETUP reads the simplified input

from unit 35, and, after assigning the default values, writes to unit 45 in

the proper $24Y input format. Since the original input to the code is still

used, it is necessary to define all of variables used in this input file. The

following is the description of the S24Y input file written to unit 45.

D.I Potential Flow Code Input Cards

Card 01 Program Control Card

(3(I1,2X), lX, 7A4, 5X, 9(n, 2X), 1X, 11)

Column Code

01 ID

04 ISV

07 ILIFT

11-38 TTITLE

Format Description

Body Number

Flag to control the saving of the

geometry for future use by the 2-D

program- 0 Do not save data

- 1 Save the input geometry data for

future use

Lift Control Flag

= 0 This is not a lifting body

= 1 This is a lifting body

Body Description

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44

47

5O

53

56

IPARA

IFIRST

ISECND

ITR

INORM

Element Geometry Flag

= 0 Linear Elements

= 1 Parabolic Elements

First-order Terms Flag

-- 0 No first-orderterms

- 1 First derivative term

- 2 Curvature term

- 3 Both first-orderterms

Second-order terms flag

-- 0 No second-order terms

- 1 Second derivative term

- 2 Curvature squared term

- 3 Both second-order terms

Geometry transformation card

= 0 Transformation card will not

be input

- 1 Geometry transformation card

will be input

Ellipse generation. Ellipse

generation card will be input.

Transformation card will not

be input.

Ellipse generation. Ellipse

generation card will be input.

Transformation card willbe input.

=2

=3

Geometry Normalization Card

= 0 Geometry will not be normalized

- 1 All of the geometry data

(x and y) will be divided by

the chord length before use by

the potential flow program

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59 IBOD Body Disposition Flag

This flag together with the IDOLD

parameter controls the sequence of

the potential flow analysis part of

the program. With the use of these

two flags and the ISV parameter, it

is possible to perform a variety of

multi-element problems with a

minimum of input data. For normal

useage when all of the geometry data

are input, only the IBOD -- 1 and = 2

are used.

= 1 New geometry is being used.

The storage of geometry data

for the potential flow solution

will start with this body.

= 2 New geometry is being input, but

this is not the first body.

This body will be added to the

sequence of body data already input.

= 3 New geometry is being input, but

it is to be added to an old

sequence of data.

All previously saved geometry will

be used

The geometry for this body will

be selected from the previously

saved data (body IDOLD will be

selected). This selected body

will be added to the current string

of bodies.

Previously saved geometry data

will be used with the body

number indicated by the IDOLD

parameter removed from the solution

=4

-5

---6

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62 IDOLD

65 IPVOR

Old Body ID Number

This parameter is used in

conjunction with the IBOD parameter

in selecting which previously saved

shape is to be retrieved as the

present body

Vorticity Distribution Flag

= 0 Use constant vortlcity between

the body elements

- 1 Use a variable vorticity distribution

68 LAST Last Body Flag

= 0 This is not the last body.

After this body is input, the

program will return to read another

Body Title and Control Card for the

next body.

= 1 This is the last body.

72 ITYPE Card Type Flag

=I

X-Coordinate Cards (6F12.7, 2X, I1, lX, I1, lX, I1)

Column Code Format Description

1-12 X(1)13-24 X(2)25-36 X(3)37-48 X(4)49-60 X(5)61-72 X(6)

6F12.7 x-coordinates of the body geometry.

Up to six points may be on each card

depending upon how the INO flag is set.

75 INO I1 Number of data points on the card

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77 ISTAT I1

(Maximum of six)

Last Card Flag

= 0 This is not the last

x-coordinate card. More cards will follow.

= 1 This is the last x-coordinate card.

79 ITYPE I1 Card Type Flag

--3

Y-Coordinate Cards (6F12.7, 2X, I1, lX, I1, lX, I1)

Column Code Format Description

1-12 y(1)13-24 v(2)25-36 Y(3)

37-48 Y(4)

49-60 Y(5)

61-72 v(6)

6F12.7 y-coordinates of the body geometry.

Up to six points may be input on

each card depending upon how the

INO flag is set.

75 INO I1 Number of data points on the card

(Maximum of six)

77 ISTAT Ii Last Card Flag

-- 0 This isnot the last

y-coordinate card. More cards

willfollow.

-1 This isthe lasty-coordinate

card

79 ITYPE I1 Card Type Flag

=4

208

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Flow Title Card (15A4, llX, I1)

Column Code Format Description

1-60 FTITLE 15A4 Title

72 ITYPE I1 Card Type Flag

=8

Flow Control Card

(I1,4X,F 10.5,2X,I1,2X,F 10.5,5(4X.I1),9X,I1,3X,II,I2,I1)

Column Code Format

1 INCLT I1

6-15 CLT F10.5

18 ICHORD I1

21-30 CCL F10.5

Description

c_, a Flag

= 0 Airfoil angle of attack, a, is

input.

=1 Total lift coefficient, C,, is

Value of the angle of attack or lift

coefficient depending on how the

INCLT flag was set

Reference Length Flag

= 0 The reference length used to

calculate C, is set = 1.0

= 1 The reference length used to

calculate C, will be input as CCL

The input value for the reference

length used in calculating Ce

(generally the airfoil chord)

35 IND I1 Individual Solution Flag

$24Y is capable of calculating the

potential flow about up to 6 bodies

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and then superimpose the results of

each. The possible values of IND are

as follows:

= 0 Edge velocities are not calculated

for each body

= 1 Edge velocities are calculated for

each body

In LEWICE, only one body is input and the

edge velocities are always required.

Therefore, IND = 1.

4O ISOL II Matrix Solution Method Control Flag

= 0 Use routine SOLVIT for the

matrix solution (used when a very

large number of points have been input)

= 1 Use routine QUASI for the matrix

solution

= 2 Use routine MIS1 for the matrix

solution. The maximum number

of geometry points = 101. If

the number of points is greater

than 101, the program will

automatically shift to use SOLVIT.

45 IOFF I1 Off-body Calculation Flag

= 0 Off-body points will not be

calculated

= 1 Off-body points will be calculated

50 NONU Ii Non-uniform Flow Flag

= 0 Non-uniform flow is not input

= 0 Non-uniform flow will be input.

The number of flows input = NONU

(maximum of six). When this option

is used, the program sets ISOL = 1.

210

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55 NBNU II

65 IPRINT I1

The number of bodies for which

the non-uniform flows are input

Print/punch Flag

= 0 Normal output

= 2 Print the individual matrices

= 7 Punch the output on cards

70 MORE I1 Last Case Flag

= 0 This is the last case

= 1 This is not the last case

Another set of Flow Title and

Flow Control cards (and any

non-uniform or off-body cards)

will be expected after this case

is completed

70-71 IFILL 12 Parabolic Integration Flag

$24Y calculates the forces and

moments acting on the body using

both a trapezoidal and parabolic

integration of the calculated

coefficient. The results of

the trapezoidal calculations

are always output. The valueof IFILL determines whether the

parabolic results are printed.

72 ITYPE I1 Card Type Flag

--9

Off-Body Title and Control Card

(11, 9X, 7A4, 12X, 2(2X, I1), 2(5X, I1), 2X, I2)

211

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Column

1

11-38

53

56

62

68

Code

ID

TITLE

ITR

INORM

IDOLD

LAST

Format

I1

7A4

Ii

II

II

II

Description

Identification number for this

group of off-body points. Off-body

points are read in groups of up to

100. There is no limit on the number

of groups.

Title or description for this

group of off-body points

Coordinate Transformation Flag

See the ITR parameter on the Body Titleand Control Card

Coordinate Normalization Flag

= 0 Off-body coordinates will not

be normalized

= 1 Normalize the coordinates by

the input chord or by the chord

for the body with ID = IDOLD

Body Selection Flag for Normalizing

Off-body Points

- 0 Use the input chord to normalize

the off-body points

= 0 Use the chord for body withID = IDOLD to normalize the

off-body points

Off-body Group Termination Flag

= 0 Another group of off-body

points will follow this group

= 1 This is the last group of off-

body points

212

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71-72 ITYPE I2 Card Type Flag

= 21

Off-Body X-Coordinate Cards (6F12.7, 2X, I1, IX, II, IX, I1)

Column Code Format Description

,-,2 X(l)13-24 x(2)2s-36 x(3)37-48 x(4)61-72 x(6)

6F12.7 x-coordinates of the off-body

points. Up to six points may be

input on each card depending upon

how the INO flag is set.

75 INO 11 Number of data points on the card

77 ISTAT I1 Last Card Flag

= 0 This is not the last

x-coordinate card. More cards

will follow.

= 1 This is the last x-coordinate

card

79 ITYPE I1 Card Type Flag

--3

Off Body Y-Coordinate Cards (6F12.7, 2X, I1, lX, I1, 1X, I1)

Column Code Format Description

1-12 Y(1)

13-24 Y(2)

25-36 Y(3)

37-48 Y(4)

49-60 Y(5)

61-72 Y(6)

6F12.7 y-coordinates of the off-body

points. Up to six points may be

input on each card depending upon

how the INO flag is set.

75 INO I1 Number of data points on the card

213

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77 ISTAT I1

(Maximum of six)

Last Card Flag

= 0 This is not the last y-coordinate

card. More cards will follow.

= 1 This is the last y-coordinate

card

79 ITYPE II Card Type Flag

=4

D.2 Sample Input

The input to the $24Y code using the formats described in the previous

section is written to unit 45 in subroutine SETUP. An example of the

$24Y input file on unit 45 is shown in Figure D-1. For normal operation of

LEWICE, this file should not have to be examined or modified.

214

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ORIGINAL PAGE iS

OF POOR QUALITY

! 0 1 NACA1.00000000.90000000.75000000.60000000.45000000.30000000.15000000.06000000.02500000.00575000.00125000.00037500.00057500.00125000.00375000.02500000.06000000.15000000.30000000.45000000.60000000.75000000.90000001.0000000

00120.98999990.07500000.72500000.57500000.42500000,27500000.12500000.05000000.02000000.00250000.00100000.00025000.00050000.00150000.00500000.05000000.07000000.17500000.52500000.47500000.62500000.77500000.92500000.0000000

-0.0310550-0.0459040-0.0560510-0.0602260-0.0556560-0.0385350-0.0262500-0.0106990-0.0058470-0.0029450

0,00294500.00584700.01069900.02623000.03053500.05365600.06022600.0560510"0.04590400.05105500.01490000.0000000

NACA 0012

0.98000000.05000000.70000000.55000000.40000000.25000000.1000000O.OqSO0000.01500000.00225000.00007500.00012500.00062500.00175000.00750000.03500000.08000000.20000000.35000000.50000000.65000000.00000000.95000000.0000000

1 3 3 0 0 10.9700000 0.95000000.0250000 0.00000000.6750000 0.65000000.5250000 0.50000000.3750000 0.55000000.2250000 0.20000000.0900000 0.00000000.0400000 0.05500000.0100000 0.00750000.0020000 0.00175000.0007500 0.00062500.0000000 0.00012500.0007500 0.00087500.0020000 0.00225000.0100000 0.01500000.0400000 0.04500000.0900000 0.10000000.2250000 0.25000000.5750000 0.40000000.5250000 0.55000000.6750000 0.70000000.8250000 0.05000000.9700000 0.98000000.0000000 0.0000000

0,0000000 -0,0018740 -0.0036110 -0.0052590 -0.0082510-0.0149000 -0.0179550 -0.0200880 -0.0257590 -0.0265150

-0.0544110 -0.0560870 -0.0592810 -0.0415850-0.0479060 -0.0497950 -0.0515600 -0.0531980-0.0572430 -0.0582620 -0.0590900 -0.0597070-0,0600760 -0.0596120 -0.0587940 -0.0575700-0.0507520 -0.0470040 -0.0452200 -0.0432520-0.0356740 -0.0340020 -0.0325620 -0.0304960-0.0237260 -0.0207970 -0.0172400 -0.0150780-0.0086200 -0.0081360 -0.0076230 -0.0070750-0.0051460 -0.0047660 -0.0043630 -0.0039310-0.0023560 -0.0016320 0.0000000 0.0016320

0.0054620 0.0039310 0.0043650 0.00476600.0064050 0.0070750 0.0076250 0.00015600.0123060 0.0150780 0.0172480 0.02079700.0284620 0.0304960 0.0323620 0.03408200.0410300 0.0432520 0.0452280 0.04700400.0558790 0.0575700 0.0587940 0.05961200,0600940 0.0597070 0.0590900 0.05826200.0546980 0.0551980 0.0515600 0.04979500.0437950 0.0415850 0.0392810 0.03688700.0292210 0.0265150 0.0237590 0.02088800.0117000 0.0082510 0.0052590 0.00361100.0000000 0.0000000 0.0000000 0.0000000

4.00000 0 0.00000 1 0 1 0 0NACA 0012 0 0

-0.0200000 -0.0200000 0.0000000 0.0000000 0.00000001.0000000 0.5000000 0.0000000 0.0000000 0.0000000

0 1 1 10.92500000.77500000.62500000.4750000O. 32500000. 17500000.07000000.0500000O. 00500000.00150000.00050000.00025000.00100000.00250000.02000000.05000000.12500000.27500000.42500000.57500000.72500000.87500000.90999990.0000000

-0.0117000-0.0292210-0.0437950-0.0546980-0.0600940-0.0550790-0.0410380-0.0284620-0.012,3060-0.0064050-0.0054620

0. 0023560O. 00514600,00862000. 025726O0.03567400.05075200.06007600.05724300.04790600.03441100.01795300.00187400.0000000

80 0 19

1 10.00000000.0000000

6 0 36 0 36 0 3

6056 0 36 0 36036056 0 56056036 0 56036 0 36 0 36 0 36 0 36036 0 56 0 36 0 36 0 36 O 31 13

604604604604604604604604604604604604604604604604604604604604604604604114

21 3214

D-l: Input to $24y written to unit 45.

215

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APPENDIX E

CALCULATION OF THE LOCAL EDGE VELOCITIES

Another pseudo-surface, related to the one created for particle impinge-

ment calculations, is created to determine non=dimensional edge velocities.

This pseudo-surface is formed by moving each point on the body a dis-

tance DSHIFT along the outward normal to the surface. The resulting

pseudo-surface is shown in Figure E-1. The non=dhnensional edge velocities

that were originally computed in subroutine FLOWS on the "true" surface

are recalculated in subroutine READIN on the pseudo-surface. (This re-

calculation step can be omitted with only a small change to subroutine

READIN.) The purpose of creating a pseudo-surface is to shift the surface

outward into a region where the velocity profile is smoother, thus avoiding

numerical problems that may occur when velocities must be computed on

an irregular ice surface. This method will produce higher stagnation ve-

locities but will affect the ice shape only in a relatively small region of the

airfoil unless a value of DSHIFT larger than recommended in this manual

is used.

The non-dimensional edge velocities that are recalculated on the pseudo-

surface are the ones used in the evaluation of the thermodynamic charac-

teristics of the ice surface. These non-dhmensional velocities, V_, are given

by the equation

v;= v" (E-X)Voo

The values of V_ are initially written to unit 30 in subroutine READIN

and then read in subroutine VEDGE, where they are used to calculate the

dimensional local edge velocities. The boundary layer edge velocities, IF,,

temperature, T,, and pressure, P,, are calculated from V_ using the isen-

tropic equations with the Karman-Tsien compressibility correction. These

parametes are assigned the following variable names in the computer code:

Local static pressure, (P,)

Local static temperature, (7",)

PE(I)

TE(I)

216

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Local dimensional velocity, (V,)

Local non-dimensional velocity, (V_)

VE(I) (compressible)

VT(I) (incompressible)

Each of the parameters are arrays with (I) denoting the segment number.

This appendix describes the equations used to calculate these flow proper-

ties.

The free stream roach number, total temperature, and total pressure

are first calculated using the following isentropic equations:

Voo (E-2)Moo - 20.05V_

M_TT --"T,(I +-"_-)

2

PT = Po(1+ M£p.55 "

(E-3)

(E-4)

An incompressible pressure coefficient is calculated from the non-

dimensional edge velocities using the following equation:

%,., = 1 - (V:) 2

This incompressible pressure distribution around the body is then corrected

for compressibility using the Karman-Tsien compressibility correction given

by the following equation:

]_,.= (_- M_)'/"+ _.+ (i :-Moo)'/' (E-6)

The local pressure is calculated using this corrected pressure coefficient and

the following equation:

217

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? ') (E 7)t",=t', 1 + _ e,. M_.

where Po is the free stream static pressure. If a local static pressure is

calculated to be greater than the total pressure, the local static pressure is

set equal to the total pressure.

The local mach number is calculated using the following isentropic re-

lationship between the local static and total pressures:

. 00]'"The local static temperature is determined using the following isentropic

relation:

(Te=TT 1+ (E-9)

The dimensional local edge velocity is then calculated using the isentropic

equation for the speed of sound in air and the local Mach number, e.g.,

v.=u.(2o.osv .) (E- 10)

The values of VE, TE, and PE for each body segment are then written to

unit 30.

218

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10

r6EOllrTRY FOItJIE])BY LINESI JOININ6 BODYCOORDINATES

II

'_OUI"WARD NORMALTO POINT S

15

2

>

E-l: Illustration of the pseudo-surface.

219

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APPENDIX F

EMPIRICAL RELATIONSHIP FOR

SAND GRAIN ROUGHNESS HEIGHT

THE EQUIVALENT

As discussed in Section 5.2, the size, shape, and type of ice accretion

that is formed is dependent upon the convective heat transfer rate from the

ice surface. The integral boundary layer method, described in Appendix B,

requires that a surface roughness height be specified to identify transition

to turbulent flow and evaluate the convective heat transfer characteristics

of the rough surface.

Increasing the size of the roughness elements will increase the calculated

convective heat transfer coefficient. Therefore, a calculated ice shape can

change quite drastically when various values of roughness element height are

specified. Figure F-1 shows the effect of varying the input value of the sand

grain roughness height, ko, on the calculated ice accretion shape. When

the value of k° is smaller, the amount of heat removed from the surface by

convection is reduced. Therefore, the surface temperature is not lowered

sufficiently to allow all of the ice to freeze on impact and a glaze accretion is

formed. Incrementally increasing k, increases the convective heat transfer,

thereby increasing the fraction of impinging water that freezes on contact.

As a result, the accretions begin to take on more characteristics of rime

ice. At some value of ko, sufficient heat will be removed to freeze all of the

water on impact, and a complete rime ice accretion is formed.

Empirical correlations that can be used to evaluate the effect of rough-

ness exist in the literature (Reference F-1 and F-2). Unfortunately, these

correlations are usually applicable only for a specific, well-defined type of

roughness element. None of these correlations are directly applicable to the

irregular surface roughness elements found on typical ice accretions. Fur-

thermore, the size and shape of the roughness elements on an ice surface are

dependent on the conditions at which the ice was formed. They can vary

with the icing condition, surface location, and, since the ice shape changes

with time, the icing time. While the effect of each of these parameters on

the formation of the surface roughness elements is very complex, all analyt-

ical ice accretion prediction methods must address the problem because of

the strong influence on the calculated ice accretion shape shown in FigureF-1.

220

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It has become standard practice in current ice accretion prediction

methods to develop an empirical correlation for either the surface element

roughness height (Reference F-3) or the convective heat transfer coefficient

(Reference F-4). These correlations are developed by first predicting the ice

shapes for a set of experimental ice shapes by changing the convective heat

transfer coefficient (or roughness element height) to determine the value

that yields the best agreement with experiment. Unfortunately, the corre-

lation will depend on the computational algorithm and may not be directly

applicable to any other analytical ice accretion prediction method. Since

the timestepping procedure applied in LEWICE is unique among analyti-

cal ice accretion prediction methods, an empirical correlation relating the

surface roughness height to the icing condition had to be developed.

The experimental data used to develop this correlation was obtained

by Gent (Reference F-5). This data set, shown in Figures F-2, -3, and -4,

show the effect of velocity, LWC, and static temperature on the shape of

the ice accretion formed. Also shown in the figures are the ice accretion

shapes, calculated by LEWICE, that best compare with the experimental

shape and the corresponding value of k,. The accretion shown in Figure F-

3a for LWC =0.Sg/m s was used as a baseline condition for the correlation.

Therefore, all values of k° were divided by the value of k, for this case and

plotted as a function of either velocity, LWC, or static temperature. The

resulting data points, normalized by the airfoil chord of 0.3m are shown in

Figures F-5,-6, and -7, respectively.

A correlation relating the sand grain roughness height to the icing pa-

rameter was formed by fitting the data on each of these plots with a least

squares linear or quadratic curve fit. The curve calculated from each cor-

relation is also shown in Figures F-5, -6, and -7. The equations are as

follows:

Velocity

k,/c = 0.4286 + 0.0044139(V0o) (F - 1)

Liquid Water Content

k°/c-0.5714 + 0.2457(LWC) + 1.2571(LWC) 2 (F- 2)

221

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Static Temperature

k°/c IT.\

\1000 /(F-3)

In all of these equations, k°/c)6o°°, the baseline value, is 0.00117. The ve-

locity, LWC, and static temperature are input into the equations in m/sec,

g/m s, and K, respectively. By relating them to a baseline value, the corre-

lations calculate a multiplying factor accounting for the effect of velocity,

LWC, and static temperature. The value of sand-grain roughness height to

be input is calculated using the following equation:

r ./o r ./o r 1k° = Lk0/c)bo°,vooLk°lc)b,°,LwcLk,/d_°,,JT. k,ld_,,,

(F-4)

The use of these equations is best illustrated by a numerical example.

Suppose that the ice shape for the following icing condition is to be deter-

mined.

Airfoil Chord = 0.3m

Velocity = 75.0 m/s

Static Temperature = 255.0 Ks

LWC = 0.5 g/m

The multiplying factors calculated from Equations (F-l), (F-2), and (F-

3) are 0.7596, 1.0085, and 0.7401, respectively. Substituting these values

into Equation (F-4), the final factor to be multiplied by the baseline value

and the airfoil chord is 0.5670. Therefore, for a baseline value of 0.00117

and chord of 0.3 m, the sand-grain roughness to be input into the code is

0.000199 m.

222

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As previously noted, these three correlations were developed to account

for the effect of velocity, LWC, and static temperature on the surface rough-

ness elements formed on an ice accretion. These three icing parameters were

selected because of their obvious influence on the type of ice formed, and

because a complete and consistent set of experimental data existed from

which to form a correlation. The effects of droplet diameter, body geometry,

static pressure, etc. have not been included. Also inherent in the baseline

value of sand-grain roughness height are any characteristics unique to the

facility in which the experimental ice accretion shapes were formed. These

can include levels of free-stream turbulence, LWC and droplet diameter cal-

ibrations, and possibly even the droplet size distribution produced by the

spray nozzle. Comparisons with experimental ice accretion shapes have in-

dicated that the baseline value of k,/c)b,, = 0.00117 yields good results for

the facility of Reference F-1 and the NASA Lewis Icing Research Tunnel

(IRT) but would not be expected to be appropriate for all icing facilities

and applications. A value for flight test data has not been determined but

is expected to be less than 0.00117, primarily because of the lower level of

free-stream turbulence encountered in flight.

The surface roughness, while known to be a function of icing time and

surface location, is currently specified to be constant for the entire icing

time. Sufficient experimental data does not exist to produce meaningful

correlations relating these parameters to the roughness element height.

223

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APPENDIX F

List of References

I. Kays, W.M. and Crawford, M.E. Convective Heat and Mass Trans-

fe__£r.2nd Edition, MacGraw-Hill Book Company, New York, 1980.

2. White, F.M. Viscous Fluid Flow. MacGraw-Hill Book Company,

New York, 1974.

3. Kirchner, R.D. "Aircraft Icing Roughness Features and Its Effect on

the Icing Process." AIAA-83-0111, January 1983.

4. Cansdale, J.T. and Gent, R.W. "Ice Accretion on Aerofoils in Two-

Dimensional Compressible Flow - A Theoretical Model." Royal Air-

craft Establishment Technical Report 82128, January 1983.

5. Gent, R.W., Markiewicz, R.H., and Cansdale, J.T. _Further Studies

of Helicopter Rotor Ice Accretion and Protection." Paper No. 54,

Eleventh European Rotorcraft Forum, September 1985.

224

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RIME FEATHERS

EXPERIMENT (IRT) Ks = 0.001 M

Ks = 00005 M

C--__Ks = o00q M

Ks = 0.002 M

VELOCITY (M/S) 93,88

TEMPERATURE (C) -1#.37

PRESSURE (KPA} 93.61

HUMIDITY (X) IOO.OO

LMC (G/M--3) 0.96

DROP DIAM (MICRONS) 37.50

TIME (SEC) 225.00

F-l: Effect of varying the equivalent sand-grain roughness

on the ice accretion calculated for a mixed icing condition

on a NACA 0012 airfoil section at 0.0 deg angle of attack.

225

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_,, O._

_., O._

\

\

\

\

\

\

,(

,..- .ju_¢._e,_o_t,_'?e'

-2" ._ec_, o_ "ve_'°c'_"/o__.ce

,_6

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EXPERIMENTAL

LWC - 0.25 gll,_

TI-IEORET! CAL

LWC= O,.50g/_ 3

LWC= 0.75 g/_

LWC= 1.00g/M 3

VEI. I)GI lY (It/S) 129.UII

l E I'IPFR,_|UR[ (C) -IZ.60

PRKSSURE (KI)A) 90.76

IItJM I OI lrY (X) IUU,O0

OROP OIAM (MICRONS) 20°00

TIHE (SEC) 120.00

a. Angle of attack = 0.0°

F-3: Effectof LWC on ice accretion shape.

227

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EXPER| RENTAL

LgC = 0.25 g/M 3

THEORETICAL

LWC ffi 0.50 g/M 3

LgC = 1.00 g/t43

UELOCIIY (14/S) 129.00

1EHI'ERfiTURE (C) -12,bO

PRF, SSUgE (KI)h) ?fJ, 16

IIUtlIDI IY (x) 10o.00

IJROP UIAfl (HICRDNS) 20°00

TitlE (SEC) 120.00

b. Angle of attack = 4.0°

F-3: Concluded.

228

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EXPERIRENTAL

r,. -8.oc ......

Ts = -/2.6 C

Ts = -22.9 C

V[LOCITy (N/S) 131,00

PR/SSUR[ (KP_) 90,75HUNIDJIy ¢X)

LHC (O/H--3) IO0,gO0.50

DROP DIAN'¢M|CRONS) 24,00f|H[ ISLE) •

IEo,o0

F-4: Effect of static temperature on ice accretion shape.

229

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1.5

1.0

.5

I I I I50 100 150 200

VELOCITY, _v's

F-5: Emperical relationship for equivalent sand-grain roughness

as a function of velocity.

2.5

2.0

_1.5

t_

.5

-- 0 0_0 (FIG. F-3A) 0

I I I I I.2 .q .6 .8 1.0

LIQUID WATER CONTENT, glM3

F-6: Emperical relationship for equivalent sand-grain roughness

as a function of LWC.

230

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1.0

o5 m

I I I 1-250 260 270 280

STAT[CTER°ERATURE,K

F-7: Emperical relationship for equivalent sand-grain roughness

as a function of static temperature.

231

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Report Documentation PageNat*oriel Aeronauhcs and

SDace Admlnistrallon

I. ReportNo. 2. GovernmentAccessionNo. 3. Recipient'sCatalog No.

NASA CR- 185129

4. Titleand Subtitle

Users Manual for the NASA Lewis Ice Accretion

Prediction Code (LEWICE)

7. Author(s)

Gary A. Ruff and Brian M. Bcrkowitz

g. PerformingOrganizationName and Address

Sverdrup Technology, Inc.

Lewis Research Center Group

2001 Aerospace ParkwayBrook Park. Ohio 44142

12 SponsoringAgencyName and Address

National Aeronautics and Space Administration

i Lewis Research CenterCleveland, Ohio 44135-3191

5. ReportDate

May 1990

6. PerformingOrganization Code

8. PerformingOrganizationReportNo

None

10. WorkUnit No.

505-68-11

11. ContractorGrantNo.

NAS3-25266

13. Type of Reportand Period Covered

Contractor ReportFinal

14. SponsoringAgencyCode

i15. Supplementary Notes

Project Manager, J.J. Reinmann, Propulsion Systems Division, NASA Lewis Research Center.

i' 16. Abstract

LEWlCE is an ice accretion prediction code that applies a time-stepping procedure to calculate the shape of an

ice accretion. The potential flow field is calculated in LEWlCE using the Douglas Hess-Smith 2-D panel code

($24Y). This potential flow field is then used to calculate the trajectories of particles and the impingement points

on the body. These calculations are performed to determine the distribution of liquid water impinging on the

body, which then serves as input to the icing thermodynamic code. The icing thermodynamic model is based on

the work of Messinger, but contains several major modifications and improvements. This model is used to

calculate the ice growth rate at each point on the surface of the geometry. By specifying an icing time increment.

the ice growth rate can be interpreted as an ice thickness which is added to the body, resulting in the generation

of new coordinates. This procedure is repeated, beginning with the potential flow calculations, until the desired

icing time is reached. The operation of LEWlCE is illustrated through the use of five examples. These examples

are representative of the types of applications expected for LEWlCE. All input and output is discussed, along

with many of the diagnostic messages contained in the code. Several error conditions that may occur in the code

for certain icing conditions are identified, and a course of action is recommended. LEWICE has been used to

calculate a variety of ice shapes, but should still be considered a research code. The code should be exercised

further to identify any shortcomings and inadequacies. Any modifications identified as a result of these cases, or

of additional experimental results, should be incorporated into the model. Using it as a test bed for improvements

to the ice accretion model is one important application of LEWICE.

17. Key Words(SuggestedbyAuthor(s)) 18. DistributionStatement

Aircraft icing Unclassified-Unlimited

Ice accretion modeling Subject Category 01Heat transfer

19. SecurityClassif. (ofthisreport) 20. SecurityCliisllif.(of thispage) 21. No.of pages 22. Price*

Unclassified Unclassified 233 A 10

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