NASA-CR-174647

N/ ANational Aeronautics andSpace Administration

R84AEB380

P_Cr_p')c_I

EXTENDED PARAMETRIC REPRESENTATION OFCOMPRESSOR FANS AND TURBINES

Volume !!1 - MODFAN User's Manual

FINAL REPORT

March 1984

By

General Electric Company

Aircraft Engine Business Group

Advanced Technology Programs Dept.Cincinnati, Ohio 45215

FOR

NATIONAL AERONAUTICS AND SPACE ADMINISTRATIONLEWIS RESEARCH CENTER21000 BROOKPARK ROAD

CLEVELAND, O_135

Ul

Oo

ContractNA$3-23055

SEliEIIAL 0 ELECTRICAircraft Engine Business Group

Advanced Technology Programs DepartmentCincinnati, Ohio 4621S

r--

https://ntrs.nasa.gov/search.jsp?R=19860014467 2018-06-30T00:21:26+00:00Z

1 RepOrt No 2 Government Accession No 3 Rec_p,ents Catalog %o

NASA CR-174647

4 T,tle ano SoDa,tie

Extended Parametric ReDreseptation of Compressor Fansand Turbines Vol. Ill - MhDF#N UFER'S Manual (Parametric Modulating

Flow Fan)

7 Author{s;

G.L, Converse

g Performing Organization Name and Addre_

General Electric CompanyAircraft Enaine Business GroupCincinnati, Ohio 45215

12 Sponsoring Agency Name and Address

National Aeronautics and Space AdministrationWashinnton, D.C. 20546

5, Report Date

March 1984

6 Performing Orgamzahon Co0e

8. Performing Organization Report _o

R84_AEB380

10 Work Unit No

11 Contract or Grant No

NAS3-23055

13, Type of Report and Period Covered

Contract ReportAugust 1982 - October 1983

14 Sponsoring Agency Code

15 Supplementary Notes

Project Mananer, James W. Gauntner, Aerospace Engineer, NASA

Lewis Research Center, Cleveland, Ohio

16 Abstract

A modeling technique for single stage flow modulating fans or centrifugal compressors has beendevelooed which will enable the user to obtain consistend and rapid off-desian performance fromdesiQn point input. The fan flow modulation may be obtained by either a VIGV (variable inlet auidevane) or a VPF (variable pitch rotor) option, Only the VIGV option is available for the centrifugalcompressor. The modelinn technique has been incorporated into a time-sharinm proaram to facilitateits use, Because this report contains a description of the input output data, values of typicalinputs, and example cases, it is suitable as a user's manual. This report is the last of a three

volume set describina the parametric representation of compressor fans, and turbines. The titlesof the three volumes are given below:

(I) Volume I CMGEN USER'S Manual (Parametric Compressor Generator)(2) Volume II PART USER's Manual (Parametric Turbine)(3) Volume I]I MODFAN USER's Manual (Parametric Modulating Flow Fan)

17. Key Words (Suggested by Author(s))

Parametric Fans

Parametric Centrifugal CompressorsOff-Desion PerformanceFlow Modulation

19 S_ur,tv Cla_if. (of this report)

Unclassi.fied

18 Distribution Statement

20. Security Classif. (of this page) 21_ No. of Pages

Unclassified 50

22 Pr,ce"

NASA-C-168 (Rev I0-75)

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

2.0 PROGRAM STRUCTURE

3.0 PROGRAM INPUTS 5

4.0 PROGRAM OUTPUTS 9

5.0 PROGRAM DIAGNOSTICS i0

6.0 EXAMPLE CASES 12

7.0 ANALYTICAL BACKGROUND

7.1 Method of Map Generation

7.2 Discussion of Variable Geometry Options for

Axial Flow Fans

7.2.1 Variable Inlet Guide Vane (VIGV) Option

7.2.2 Variable Pitch Rotor (VPF) Option

7.3 Discussion of Centrifugal Compressor Option

7.3.1 Fixed Geometry Centrifugal Compressors

7.3.2 Variable Inlet Guide Vanes (VIGV)

23

23

24

24

27

37

37

37

REFERENCES 46

lq{ECEDING PAGE ,BLANK NOT FILblED

iii

LIST OF FIGURES

FIGURE NO.

i,

2.

3.

4.

5.

6.

7.

8.

9.

I0.

ii.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

DESCRIPTION PAGE

Flow Chart Showing Flow of Control in MODFAN 4

MODFAN Sample Terminal Conversation 6

Parametric Fan Performance Map (PR=I.6) 8

Vector Diagram for Variable Inlet Guide Vanes (VIGV) 25

Stage Characteristics for VIGV Axial-Flow Fan 26

Parametric VIGV Axial Flow Fan (STPI=- i0.0 °) 28

Parametric VIGV Axial Flow Fan (STPI=0.0 °) 29

Parametric VIGV Axial Flow Fan (STPI=+20.0 °) 30

Parametric VIGV Axial Flow Fan (STPI=+40.0 °) 31

Flow Variation Along Min-Loss Locus 32

(Single Stage VIGV Fan)

Pressure Rise Variation Along Min-Loss Locus 33

(Single Stage VIGV Fan)

Efficiency Variation Along Min-Loss Locus 34

(Single Stage VIGV Fan)

Vector Diagram for Variable Pitch Rotor (VPF) 35

Stage Characteristics for VPF 36

Flow Variation Along Min-Loss Line (Centrifugal Compressor) 38

Pressure Rise Variation Along Min-Loss Locus 39

(Centrifugal Compressor)

Efficiency Variation Along Min-Loss Locus 40

(Centrifugal Compressor)

Stage Characteristic for VIGV (Centrifugal Compressor) 42

Flow Variation Along Min-Loss Locus 43

(VIGV Centrifugal Compressor - Impeller Only)

Pressure Rise Variation Along Min-Loss Locus 44

(VIGV Centrifugal Compressor - Impeller Only)

Efficiency Variation Along Min-Loss Line 45

(VIGV Centrifugal Compressor - Impeller Only)

1.0 INTRODUCTION

The NASA Lewis Research Center employs a general computer program NNEP (Ref.l)

for calculating the thermodynamic performance of jet propulsion engines. To calculate

off-design engine performance, the _EP user must input component maps defining the

characteristics of the various components over their full range of operating con-

ditions.

For early cycle analysis of advanced propulsion systems, these map characteris-

tics are not generally known because the geometry of the component has not been

specified. Furthermore, the typical user of NNEP is not sufficiently knowledge-

able and/or cannot afford the time to do an extensive design followed by an off-design

analysis of the component in question to define the map characteristics. Typically,

in this early stage, the user scales some available map.

The available methods for scaling maps can lead to significant errors in com-

ponent representations. A traditional method of scaling a compressor map retains the

flow speed relation of the base map and applies a constant pressure rise scalar cal-

culated at the design point. Size scaling is, of course, legitimate. The accuracy of

such a procedure can be considerably improved by using parametrically generated com-

ponent maps. A parametric component representation can be thought of as a scaling pro-

cedure which uses the key design point parameters to impact the fundamental differences

in the map characteristics when generating the component maps.

The objective of the present study is an improved method of representing single

stage flow modulating fans and/or compressors of either the axial or centrifugal types

when performing calculations of off-design performance for advanced air-breathing jet

engines. The axial flow machines include flow modulation through either variable inlet

guide vanes (VIGV) or variable rotor pitch (VPF). The centrifugal compressors include

only the variable inlet guide vane (VIGV) option. This method, which is a computer pro-

gram called MODFAN (i.e., flow modulating fan) is compatible in both form and format

with the cycle program of Reference 1 and the example map representation of Reference

2.

This report is a user's manual for the computer program MODFAN and contains a

description of the input-output data, values of typicel inputs, and sample cases. A

brief description of the engineering analysis used to generate a program is given near

the end of the report, i

The program uses design point data and semi-empirical correlations to

generate off-design values of corrected flow,efficiency, and pressure ratio over a

range of blade angles, corrected speeds, and pressure ratio parameters specified

by the user.

2.0 PROGRAM STRUCTURE

A flow chart showing the flow of control in the MODFAN program is shown in

Figure I. The program first displays a description of the design point variables

together with the default values. The user can then change the default values as

desired. The input is then checked and the updated input displayed. This completes

the input phase of the program. The design point calculations are then carried out.

These calculations determine the blade row overall geometries from the design

point input.

Once the design point calculations have been completed, the off-design calcula-

tion can begin. The calculations for each of the desired angles, speeds, and *R values

are carried out in a set of nested DO loops. For each angle and speed, the min-loss

point (i.e., the map backbone) is first located. Then the values of work coefficient

both at stall and at a pressure ratio of unity are determined. These values of work

coefficient form the upper and lower limits of the speed line. The R values are then

converted into equivalent work coefficient values, and the fan characteristics

determined. When the inner or R DO loop is completed the speed is incremented and the

calculation repeated_ when all speeds are completed, the angle is incremented.

After the off-design calculation has been completed, MODFAN writes the three

data sets required for the computer program NNEP input.

*R is a measure of the relative distance along a speed line starting from R=I at

stall.

READ INPUT

PROCESS INPUT I

** DESIGN POINT CALC. **

CALL DESPTX

CALL STALLX (IDES=I)

*** OFF-DESIGN CALC. ***

(For all angles, speeds, and R values)

DO I = l, NANGI

DO J = l, NSPDS

CALL MINLOS

CALL STALLX (IDES=O)CALL PRCHOP

DO K = l, NR

CALL STAGEX

CONTINUE

CONTINUE

CONTINUE

I NAsAOUTPUTCALL WGTOPX /-

Flow

EFF

PR

FIGURE I. FLOW CHART SHOWING FLOW OF CONTROL IN MODFAN

3.0 PROGRAM INPUTS

Most of the MODFAN inputs are of the free-field format (NAMELIST) type, and

begin in column two. The only exception is the initial type switch which requires

either a 1 or 0 as a response. The program first gives a brief description of the

variables used in the NAMELIST INPUT. The default settings of these variables are

then displayed. The user can then enter changes in the design point values and/or

the range of angle settings, speeds, and R values desired. If the user wishes the

program to generate a value for the design point efficiency, a zero value should be

input for EFFD. The program will then echo the updated NAMELIST and go into exe-

cution. Upon completion, the program will display a message to the effect that the

NASA output files have been written on file codes 30, 31, and 32.

A sample of this showing the terminal conversation is shown in Figure 2 .

This example is for a axial flow fan having fixed geometry. Note that all of the

design point values have been reset as well as the range of inlet guide vane angles

and corrected speeds. The range of R values has not been altered. The R values are

used to fix a point on a speed line. The R value is unity at the stall line and in-

creases along a constant speed line as the flow increases. The algorithm used in

MODFAN forces a value of R equal to two at the min-loss point which is slightly

below the peak efficiency on the speed line. The concept of min-loss is discussed

in detail in Reference 3 .

The fan map generated by the program from the input values given in Figure 2

is shown in Figure 3. The locus of the R=I and R=2 lines have been indicated on

the figure.

OF PO(_FC -,_r"_i_,_.,_,++_i_ +:

"*'''''*tet'PARAMETRIC FLOW MODULATING FAN **+'*'**eem_

eM'O_D*F*AtNn

AXIAL OR CENT COMPRESSOR? I-CENT;B OR CR-AXIAL-J

DESCRIPTION OF INPUT VARIABLES IN MODFAN PROGRAM(NAMELIST INPUT)

ITYPE-1 VIGVITYPE-2 VPF(NO IGV )

DESIGN POINT VALUES OF:

POPD PRESSURE RATIO(TOTAL-TO-TOTAL)EFFD ADIABATIC EFFICIENCY(TOTAL-TO TOTAL)W1D INLET CORRECTED FLOWPSID ROTOR EXIT MERIDIONAL LOADING(ZGOtDH/U2-12)WQA1D INLET CORRECTED FLOW PER UNIT AREAXMZ2D MERIDIONAL MACH NO AT ROTOR EXITSMD CONSTANT SPEED STALL MARGIN(PERCENT)STPID IGV METAL ANGLE

GEOMETRY SPECIFICATIONS

A3QAZ STATOR INLET TO ROTOR EXIT AREA PATIORRAT INLET HUB TO TIP RADIUS RATIOROOI RATIO OF ROTOR EXIT TO INLET RADII (MERIDIONAL LINE)

MAP RANGE (ARRAY VALUES MUST BE IN ASCENDING ORDER)

NRARNSPDSAPCNCNSTP1ASTPINROT1AROT1

NO OF R VALUES TO BE CALCULATEDARRAY OF R VALUES(I=STALL,Z=MIN-LOSS)NO OF SPEED LINESARRAY OF SPEEDS (DECIMAL PERCENT)NO OF IGV SETTINGSARRAY OF IGV ANGLES(-Ig TO 4m DEG)NO OF ROTOR PITCH SETTINGSARRAY OF ROTOR PITCH ANGLES( -5 TO 5 DEG)

NAMELIST INPUTITYPE = I,PQPD - 1.655g,WID = ZZ3.8_#_,WQAID = 41,_7_,SMD " I4.I_g_,A3QA2 - g.96#g,ROQI = l._Bgg,NR - IIAR(1)

I I.gggB,5 1.8_g_,9 Z.6_gg,

EFFD - B.B34B.PSID - _.8ZZ6,XMZZD - B.45BB,STPtD - g.

!

RRAT - g.5_g_,

2.ggBg, 2.2ggg,2.8g_g, 3.gBBB,

Figure 2. MODFAN Sample Terminal Conversation.

6

OR|GIN.,_.L p,.:l.:,, r!

OF pOOR C ',?i't_'/_"

NSPDS = 6APCNC{I) =

1 B.Sg_B,5 1._9B,

NSTPI - 3ASTPI(I) -

! B. oNROTI - gAROTI(I) =

1 B.END NAMELIST

ENTER CHANGES TO

_.7ggg, B.8H_,l.l_,

2_.gg_m, 4w._gBB,

INPUT

NAHELIST INPUT=$INPUT NSTPI/ASTPI=9.H,-PQPD=l.62,EFFD=.84,VQAID=4g.g.V1D=219.2,PSID=.863,=XMZ2D=.S,SHD=Z_.g. STPID=B.g,A3QAZ=I.B5,RRAT=.5,ROQI=I.B,=NSPDS/APCNC=.5,.7,.9,1.H,I.I,=$

B.9gBB,

INPUTI,

1.629g,219.zggg,

4g.gggg,2g.ggg_,

l.g5gg,

11m

1._g,1.S_gg,Z.6ggg,

5

1.1ggg,1

NAHELIST[TYPE =PQPD =WID =WGA1D =SHD =A3QA2 =ROQI =NRAR(I)

I5g

NSPDS -APCNC([) =

!5

NSTP! -ASTPI(I) •

INROT[ =AROTI(1) -

I g.END NAMELIST INPUT

OUTPUT ON IFC=3g,31,3Z

EFFD = W.84gB,PSID • B.B63g,XMZZD = g.5ggB,STPID = g.RRAT = _.5ggg,

1.2ggH, 1.4ggg, 1.6gHg,2.gggg, 2.2ggg, Z.4Hgg,2.8g_g. 3.g_,

PROGRAM COMPLETE &

Figure 2. MODFAN Sample Terminal Conversation (Continued).

0 °

L,_•i.;d- N=.-;d--. ' '_u =--!--,--_b-•- _--!-. I d-d •

-_..f.,ff.-!-i.-.:-_.7•

'--!7 ? I"--K "_+_

r ":' -i _ I- '--'-!'7-" :

I-f ._!_.!._•.:.t"I:.................... a_.L

::::.7:£:[ :_-T2!-: :!:;i::i 7- I i-T#-: 7-I-i

_-;- .--7 f--_-;-!....... "+| "T'T" i'- ---.-i-+.

ii;i T.r -P!-........._!z_...... t 7 ............. i----P-

:2:_- -" :T;: ''

' t!il,i_i 4;I

i ..... .L.... -!-. t-!.• _-; t .... !..........!•i i

. !: I=:'LI. '

•:: : !: :i: 7i:711%_ ..i !i'-I .... l ....... ! i-

i:i tiliiii""

..... i ,i:-]i _

.... ,-r -_ .....

............. I.

...... ! - .... [

'i L-,2 : _..,...

..... _ 7........

' I I t L:.-_.i : _L:4.

: : " :: i: ........LLLb-i. i •....... _ _- ...., .-._-.

i-£ .... :,-+.i...:i::: :;i ::2::::::: + L-_.+._ ,.+ _,-;. _ .+-!_ ! I , i i

,-÷ _+-! !--_-*.-Nd:-.

6"_3N3

:::"'::', I :.::::: ]

4 •0 PROGRAM OUTPUTS

The basic output from the program consists of three tables. These tables

show the variation in corrected flow, efficiency, and pressure ratio for each of

the vane or rotor angles, R-values, and corrected speeds specified in the input.

The output tables for the default cases are shown on pages 15 thru 17 and 20 thru

22. The table structure is compatible with NASA cycle deck requirements given in

Reference 2 (pages 23 and 24).

The output tables can be visualized as three dimensional, composed of a

series of planes with each plane assigned a value of angle position, STPI or ROTI.

Then in each angle plane, the dependent variable (ordinate axis) is a function of

corrected speed, SPED, and R value. The dependent variables are respectively

corrected flow, total-to-total efficiency, and pressure ratio.

For example, in the output table on page 20 the 12 lines of the dependent

variable correspond to the 6 values of corrected speed, two lines per speed. Within

each speed there are ii R values.

It should be noted that for pressure ratios less than unity the efficiency is

negative. These efficiency values are not fncorrect, however, the efficiency be-

havior in this region makes curve fitting and interpolation of efficiency values

extremely difficult. For this reason many engine manufactures use some form of locus

or temperature ratio parameter rather than efficiency for interpolation. The solution

used here was to simply discard the information below unity pressure ratio and to

display the solution for unity pressure ratio for all values of R at which the

pressure ratio is less than unity. This means that identical values of pressure ratio

(PR=I.0), flow and efficiency (EFF=O.0) will appear in the output table on any speed

line where the value of R results in a pressure ratio less than unity.

9

5.0 PROGRAM DIAGNOSTICS

The MODF_N computer program contains error printouts to aid the user in

trouble shooting. A list of the error messages and their meaning are given

below.

ERROR IN SUBROUTINE MINLOS.

PCN = F7.3, STPI = F7.3, ROTI = F7.3, ERR = F7.4

Failure to find the mln-loss or "backbone location"

at the input corrected speed and angle. The rotor

is not choked.

ERROR IN SUBROUTINE ROTORC

TANAI = F7.3, PCN = F7.3, PSI2J = F7.3, ERR = F7.4

Failure in the Newton-Raphson loop which solve the

continuity equation across the rotor for the case

where the rotor is choked.

NO STALL INTERSECTION FOUhU): PCN = F7.2

Failure in the STALLX Subroutine. No stall intersection

found at the specified speed and 4>2.

i0

There are three iterations in the program which are balanced using the Method

of False Position. This method is contained in the subroutine QIREXX.A maximumof

25 passes is allowed for any single iteration to balance. If the It_r_t_n_ 4o=s not -

balance within the specified tolerance the error messageshownbelow will printoutwith the number of the offending iteration in the I5 format field.QIRECTRERROR- - (CALLINGLINE = I5)

QIRE CALLINGLOOP ROUTINE COMMENTS

I MINLOS

2 STALLX

3 PRCHOP

Calculation of Min-Loss or "Backbone"

location at the input corrected speed

and angle with Rotor choked.

Calculation of the intersection of

speed line and stall line (R=I).

Calculation of the corrected flow at

unity pressure ratio.

Ii

6.0 EXAMPLE CASES

Two example cases are given in order to illustrate the use of the program.

The first case utilizes the default settings to generate a single stage fan having

variable inlet guide vanes (VIGV). The second case uses the default settings to

generate a single stage fixed geometry centrifugal compressor.

A complete record of the two terminal sessions including a listing of the

output tables is given on the following pages. The program inputs and outputs have

been discussed previously in Sections 3.0 and 4.0.

12

(_, L, ,-':_-;' 7 ..

OF FOg;P, QU_,LI'_"_'

*Q***_t_t_*PARAMETRIC FLOW MODULATING FAN *nmf****'°*tt

_M*O*D*F*A'N*

AXIAL OR CENT COMPRESSOR? 1-CENT;B OR CR-AXIAL

DESCRIPTION OF INPUT VARIABLES IN MOOFAN PROGRAM(NAMELIST INPUT)

ITYPE-1 VIGVITVPE-2 VPF(NO IGV )

DESIGN POINT VALUES OF:

PQPDEFFDWIDPSIDWQA1DXMZ2DSMOSTPID

PRESSURE RATIO(TOTAL-TO-TOTAL)ADIABATIC EFFICIENCY(TOTAL-TO TOTAL)INLET CORRECTED FLOWROTOR EXIT MERIDIONAL LOADING(2GJ'DH/UZ'*Z)INLET CORRECTED FLOW PER UNIT AREAMERIDIONAL MACH NO AT ROTOR EXITCONSTANT SPEED STALL MARGIN(PERCENT)IGV HETAL ANGLE

GEOMETRY SPECIFICATIONS

A3QAZRRATROQI

STATOR INLET TO ROTOR EXIT AREA RATIOINLET HUB TO TIP RADIUS RATIORATIO OF ROTOR EXIT TO INLET RADII (MERIDIONAL LINE)

MAP RANGE (ARRAY VALUES MUST BE IN ASCENDING ORDER)

NRARNSPDSAPCNCNSTPIASfPI

NROTIAROT1

NO OF R VALUES TO BE CALCULATEDARRAY OF R VALUES(1-STALL,Z-MIN-LOSS)NO OF SPEED LINESARRAY OF SPEEDS (DECIMAL PERCENT)NO OF IGV SETTINGSARRAY OF IGV ANGLES(-Ig TO 4_ DEG)NO OF ROTOR PITCH SETTINGSARRAY OF ROTOR PITCH ANGLES( -5 TO 5 DEG)

NAMELISTITYPE -

PQPD -WIO -WQA1D -SMD -A3QAZ .ROQI -NRAR(1)

L5g

INPUTI,

1.655B,223.8_B,

41.B7_B,14.IBB_,

I.BB_B,II

1.B_Bm,1.8H_W,

EFFD F W.8348,PSID - _.8226,XMZ2D - W.45##.STPID - _. )

RRAT = _.sggB)

1.2#8B,2.B_H_.2.e_ee,

1.4BgB,

3.BgBE,

13

OF pOOR Q_,-,Lt,

NSPDS = 6APCNC(I}_-

! B.SBB_,5 1.JBSB,

NSTP! - 3ASTPI(I) =

! B. ,NROT1 = WAROT[(I)

1 f.

Z_.BWBW,

END NAHELIST INPUTENTER CHANGES TO NAHELIST INPUT=SINPUT$

NAMELIST INPUTITYPE = 1,PQPD = 1.655B,WID = ZZ3.SBBB,WQA1D = 41.B7Bm,SMD = 14.tggm,A3QAZ = B.96_,ROQI = 1._H,NR = 11AR(I) =

1 1.BWBm,S 1.8_B,9 2.6_m,

NSPDS " 6APCNC(I) "

!S

NSTP1 •ASTPI(I) =

INROT$ =AROT1 ( ! ) =

1 B.END NAHEL I ST

B.5B_B,

3

INPUTOUTPUT ON IFC=3B,31,3Z

EFFD -PSID =XMZZD =STP10 =RRAT =

Z.#g_B,

Z#.#_#,

PROGRAH COHPLETE &

B.SBBJ,

4B.IWBB,

B.O34B,W.8ZZ6,E.45BB,_, •

W.5BB_•

3.#_,

_.8gBB,

4B.B_O,

B.gBBB,

14

1001 P-FAN FLOW VS. R0

STPI 3 O. 0 20.0o0

SPED 6 O. bOO O. 700

R ll I .000 1.2o0

N 11 2. 400 2.6n0

FLOW 1 I 93. 3 I -q'/ 100..G,_,60

FLOW 11 136. _:715 1 ,'_;1. G,_O7

FL¢IW 11 140 Ollb 147,.L'_8

FL.PbW 11 176.5"392 17b.7129

FLOW 11 164.2158 170. I,,1;,'2

FLOW 11 194.0171 lq4.0171

FLOW 11 187.6732 1.02.PI._0

FLOW 11 210.7646 210. 7C.16

FLOW 11 209.7717 213.;71 7G

FLOW I 1 225. 945(I 225. G-'130

FLOW I1 2_.7.-191:1 ?29. 7C J7

FLOW !1 238.9715 73_.13_4

SPED 6 0._00 0.700

R I1 1.000 1.200

R I1 2.400 _.600

FLO_ 11 79.0908 _5.,;?_5

FLOW 11 117.5,o_0 120.91R5

FLOW I1 117.5_62 1;24.b625

SPFFI3,.'t I._ , r|{lO

O. ft,_O

1 . ,1l ,0

;:. 000

_n,, . .o,719

l"_f c,P,07

i =-.,i. ",., / _1 i_;.;'1_()

I /G. ,r'.G,._F;

I _,I. Ol/I

I cj ,-..'=,C;,.-1.'?

2 I 0. /G_t ";

"._G. _,ri..li

• ;0% %.-Ic,._rl

AND ANGL

O. 900

I . r;, .0

3. Ot,O

1114.1715

I "i_;. b "'H1/

I t:i_ , tj'l¢ "1

1 /t;. "/I :-3

i¢t -'_ ;_,'_:',_

191.0171

_:.l'll . 7 ! /4

;'1(1. 7_; 16

_-',_:_. 94',J0

1.000

i._o0

i?I.GP18

186.8074

_n,_.3_10

221.6648

73_._316

1.100

2.000

12:7 L_03G

I 71 3347

_._00

132.G_90

174._529

193.R546

210._036

2_5.3357

238._C61

(J. _lO, i

1. -40n

2 i'll ici

._1 f_! 27

2 I ft72t.

: I _,lgG

2Jg. 132.1

O. _luo

1. GoO

3,0 3ft

(;17. t_,_/1

121.87_-b

I :'_7 2.'_4.'I

l.OnO

1.Rno

103._341

142.7091

1.100

2.000

10_.7800

147.4722

2.2O0

113.5039

151.2191

FL_W 11 153.5704 154.-1_'1_

FLOW 11 137.41_97 1-14.?,:;_5

FLOW 11 169.,11P2 169..1(,11

FLOW I1 157..1'_t;R 16q.5344FLOW I I 104.2108 1_4._108

FLOW I1 176.8"/37 181.9r=67

FLOW 11 198.36(_5 190._1G05

FLOW I1 195, 7194 199,C,"JG3

FL ,'_W 11 211 . 3".' 3"_ 21 ! . "t/3."1

'.1

Cil

_(:

t, ']

211

•17,; I

4574

4611

?I0_

40_8

bd77

_73;I

1"%.i. 4761

I_C 0%14

IG_.4611

173.8_36

i8.1.21i_8

1. rl. ,'142,?

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R 11 2.400 2.600FLOW II 67.3477 72 R'i3_

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FLOW Ii 131.217l 1:37.0/71 1.17 ."i(;4_. 1.17.0_.,9.1 151.1:319

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FLOW 1 I 162.3147 166.70_5 I /rt. ' ";,"_" 1 /:i. R_3G 176. £3."0

FLr_W I1 180.?.639 If_0._639 1_0 ?L,3u ib0.2.;:'_9

i_UT

110

1 :;4

167

1/3

5567

3P03

9214 180. I 7,17

15

OF POOF, C_.: "

1002

STPI 3

SPED 6

R 11

R II

EFF 11

EFF 11

tFF 11

P-FAN EFF VS. R, SPI _:D, AND ANGL

0.0 20.00(1 ,1._ 000O. ,500 O. 700 0.8tin O. gO0 1 . nO0 1 . 100

1 . 000 1 . ;.'00 1 . 1orb I . oo_l 1 . 00o P.. 000

2.4no 2. t_nO 2. °)00 3. o_0

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O. ;'4.19 0.00Or, o. ('.106 0,0oo6

0.0.'30 0.'_q41 n ,n:-D.l.I 0 8",11 0.8302 0.73:iR

2.200

0.5379

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FFF

EFF

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SPED

R

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6

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0.7976 0.7Y_,3 u.7=llO

0.830o 0.83_0 n.8C01

0.8186 0.8101 0.b014O. YH60 0.7f:8_ O.¢nn4

0.79%5 0.7915 0.Tbb?

0.500 0.700 O.b_O

1.000 1.200 1.J00

2.400 2.600 2.800

00_ J;.°,'1

0 8_.*:0

0 ,I ;;:_;}

0 8!)77

0 7075

0 7913

0 8o13

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1 . 600

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0.8013

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1.8_0

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0.8340

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11

11

11

11

11

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11

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0 7_33 0.8122

0.5741 0.2127

0.'/997 0.8356

0.72b_ 0.5741

0.6106 0._405

0.7809 0.7177

0.8140 0.R383

0.8190 0.7_04

0 n_o?.

0 0149

0 86,1/

o. 8b_5

0.87_W 0.8735 0.8102 0.7535

0.0149

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0.11(.0

0.8782 0.8814 0.8694 0.8380

0.501;G

0.8t;8_ 0.8719 0.8665 0.8470

0.6_'_%

EFFEFF

EFFEFF

11

11

11

11

0.8105 0.8_7_ 0.8408 0.8_97 0.R535 0.8511 0.8419

0.8_99 0.8180 11.8017 0.780;_

0.7963 0.8067 0.81.18 0.8_C5 0.8234 0.8231 0.8196

0,8148 f*.811_ O.O0?u 0 8007

SPED

R

R

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EFF

EDT

611

11

1111

11

11

ilII

II

!1

!I

11

11

11

0.%00 0.7(10

1.000 1._00

2.,100 2.1,00

0.7_17 0.77360,6874 O. 11_5

0.7491 0.7901

0.76?6 O.G31G

0,7_4 q. z91o0.78_6 0.7,_4

0.7_ 0.7857

0.7924 0./7(190.7492 O.77qO

0.7948 0.78:¢9

0.7350 0.7f,34

0.7754 0.V707

0.800 O.QO0 1.OnO 1.100

1.400 I._s(10 !.800 2.000 2.200

2._00 _.noo

O e17_ 0.6_11 0.8_81 0.8595 0.0098

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_:_ : : i, ¸, :: 7'_

1003

STPI 3

SPED 6

R 11

R II

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PR I1

PR 11

PR I IPR 11

PR 11

PR I 1

PR 1 I

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PR 11

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R 11

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1.000 1.200 1.400

2.40O

1.1567

1.0175

1,9_':}7

1.1097

1 4397

! 2119

1 5894

1 3745

1 7698

1 5958

1 9818

! 8485

0.500

1.0002.4un

Z.600

1486nono

3U 70

06/3

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1714

5C,.5

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I 7blO

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9664

8251

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1.?00

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3. 000

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1.6550

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PR

PR

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PR

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11

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17

*tttt*t_QtttPARAMETRIC FLOW MODULATING FAN ttttttttt_t_

*M*O*D*F*A'N"

AXIAL OR CENT COHPRESSOR? I=CENT;B OR CR=AXIAL=1

DESCRIPTION OF INPUT VARIABLES IN HODFAN PROGRAH(NAHELIST INPUT)

ITYPE=I VIGVITYPE=Z VPF(NO IGV )

DESIGN POINT VALUES OF:

POPDEFFDWIDPSIDVOA1DXMZZDSMOSTPID

PRESSURE RATIO(TOTAL-TO-TOTAL)ADIABATIC EFFICIENCY(TOTAL-TO TOTAL)INLET CORRECTED FLOWROTOR EXIT MERIDIONAL LOADING(ZGJ*DH/U2*tZ)INLET CORRECTED FLOW PER UNIT AREAHERIDIONAL MACH NO AT ROTOR EXITCONSTANT SPEED STALL HARGIN(PERCENT)ZGV METAL ANGLE

GEOHETRY SPECIFICATIONS

A3QAZRRATROOI

STATOR INLET TO ROTOR EXIT AREA RATIOINLET HUB TO TIP RADIUS RATIORATIO OF ROTOR EXIT TO INLET RADII (MERIDIONAL LINE)

MAP RANGE (ARRAY VALUES MUST BE IN ASCENDING ORDER)

NRARNSPDSAPCNCNSTPIASTPINROT1AROT1

NO OF R VALUES TO BE CALCULATEDARRAY OF R VALUES(I-STALL,Z'HIN-LOSS)NO OF SPEED LINESARRAY OF SPEEDS (DECIMAL PERCENT)NO OF IGV SETTINGSARRAY OF IGV ANGLES(-Ig TO 4W DEG)NO OF ROTOR PITCH SETTINGSARRAY OF ROTOR PITCH ANGLES( -5 TO 5 DEG)

NAHELISTITYPE "PQPD "WlD "WQAID "SHO -A3QAZ -ROQI -NRAR( I )

159

INPUTI

4.3gg_5.5#g#

35.31#g

I.#5ggZ.g3g_

11m

l.g_ggo

EFFD - B.76_9,PSID - 1.8169,XHZZD m H.295_,STP1D " 9. ,RRAT " W.275E,

1.2BBB,

2.8_BB,

1.4B_B,2.Z#BW,

18

()F .... ....

NSPD$ - 6APCNC(I) -

! B.5ggg,5 [.gB#g,

NSTPI - 1ASTPI(I) u

[ g. ,NROTI =AROTI(I) m

l _.

END NAMELIST INPUT

ENTER CHANGES TO NAMELIST INPUT=$INPUT$

NAMELIST INPUTZTYPE = 1,PQPD = 4.3ESg,WID - 5.5_,WQAIO = 35.31gg,$MO = l_.g_g,A3QA2 = 1._5_,ROQI = 2._3g_,NR - 11AR(1) =

I l.gggg,

• 9 2.6_gg,NSPDS - 6APCNC(1) =

I g.5_,5 l._g_g,

NSTP1 - lASTPI(1) =

NROTI -AROTI(I)

1 9oENO NAHELIST INPUT

OUTPUT ON IFC=3B,31,3Z

PROGRAM COMPLETE &

EFFD =PSID =XMZZD =STPID =RRAT •

1.2_gB,2.gg_g,2.8gBg,

_.7ggg,

B.76BB,1.816B,

_.Z95g,

#.Z75W_

H.8gBg,

1.4BBE,

_.9_,

B.gggg,

19

C "" ;: i ...... ....

1 O01

STP1

SPED

R

1

6

11

P-FAN FLOW

0.0

O. 500

1 . 000

VS, R,

O. 70OI. 200

SPEED, AND ANGI_

0._00 O.qO0 1

1.400 1._o0 I

000

0001.1002.000 2.200

R II

FLOW 11

FLOW I1FLOW 11

FLOW II

FLOW II

FLOW 11

FLOW II

FLOW II

FLOW 11

FLOW II

FLOW II

2.400

2.1464

2.75t_3

3.2070

3.9032

3.7912

4.4892

4.4077

5.0777

5.0481

5.6611

_.6978

2.G00

2.P372

2.8355

:1.3132

3._N92

3. n982

4.5732

4.5106

5.1572

5.1420

5.71375.1771

2.800

2 3270

P 9135

3 41/_

4 0706

4 _033

4 6_17

4 611G

5 ?308

5 ?342

5.8008

5._5P

3.000

2.41%6

2.9S91

4. 1460

4. 1 O62

4. 72.1.3

4. 7105

5.29£2

5._P46

5._(;_0

5.q37()

4.2069

4.8073

5.4132

6. 0075

2 588_

3 7100

5 4999

6 0815

2. 6730

3.8127

4.3997

4.9924

5.5831

6.1527

FLOW 11

EOT

6.2197 6.2824 G. 3405 6.39_0

20

C" i .... ":.. '::,.- ":,

P'. / kI ' _"_ (=,::' ..... "''

1002

STP1 1

SPED 6

R I1

P-FAN EFF VS. R, SPEED, AND ANGL0.0

0.500 0.700 0.800 0 <JO0

1. 000 1. 700 I. 4no I. 6,)n

1.000

1.800 2. 200

R

EFF

EFFEFF

11

11

II

11

2.400 2.600 2.600 3 _00

0.8193 0._210 0.8217 0.[_1_

O. SnO8 0.8045 0.1082 0,7_,_9

0.82ti9 0.£272 0.8?78 O.a2/_;

0 8100

0 8272

o.8142

0.A242

EFF

EFF

EFF

EFF

11I1

11

II

0.

O.

O.

O.

0217

8136

81137918

O. 8187 O. 81 ,_{£J O. 8107

0.8147 0.81_ 0._1t34

O. 8'.002 O.C.IJ_,;G O. W'L_',_

O, 7nR6 O. 701_2 O. /,_):f.";l

0.8130

0.7920

EFF

EFF

EFF

EFF

I1

11

I1

I1

0°

O.

0.

O.

7909

7590

7589

7103

0.7895 0.7878 0.7850

0.7_9G O. IGOO 0.7,._)2

0.1581 0.75/I 0.7ti59

0.7107 0.7110 0.7111

0 7602

0 7112

0.7_00

0.7111

EFF 11

EOT

0.7106 0.7101 0.709_ 0.7089

21

ORIGINAL p,_,_:,E _",_OF POOR QUALIi "_t"

1003

STP1 1SPED 6

R 11

P-FAN PR VS. R0 SPEED, AND ANGL

0.0O. 500 O. 700 O. 800

1 • 0()0 1 . 200 I ..400

l.lO0

_.NO0 2.200

R

PR

PR

PR

11

11

11

11

2.400 2._00 2,_00

1,57G6 1.5749 1.57Z3

1.5481 1.5410 1.5:_:T3

2.3420 2.3_7 _._)0

3.0()0

1 . _.$G'._O

1. ',_24.8

P. 3;"'3 !

PR 1 1

PR I I

PR 1 1

PR 1 1

PR 11

PR 11

PR 11

PR I I

PR 1 1

EOT

2.2915 2.2734 2.P6GI

2.8961 2.R_,;_O 2._9G4

2 8365 2.8P_,1 ?.8070

3 5714 3.5_,37 3.5_%_5

5068 3.4918 3 4754

3386 4.3337 4.3_74

2748 4.2(_0R ,I.2ff44

OBG4 5.0FI6 5.07_8

0?96 5.0171 5.0036

2._517

2.7L-_3

3,_5-'8

3.4 ,,_76

4. 3 I ,-')7

4. 2274

5. oc,q.o

4.9_91

2 0708

3 5435

2.8607

3.5327

2.8.493

3.5?04

22

7.0 ANALYTICAL BACKGROUND

7.1 Method of Map Generation

The fan geometry is defined implicitly by the design point input, and the user

selected option such as VIGV settings etc. The rotor design parameters are first

separated from those of the IGV and stator. The rotor is then analyzed separately and

the IGV and stator losses added on after the rotor calculation has been completed.

The min-loss line which forms the backbone of the map is assumed to pass through

the design point. This sets the optimum incidence angle on the rotor. The flow co-

efficient (Czl/UI) is assumed to remain constant with speed along the min-loss line2

for any given value of STPI or ROT1. The work coefficient (2g J DH/U2 ) is obtained

from the flow coefficient, rotor geometry, and rotor continuity. The rotor loss at

min-loss is obtained at the design point. This loss is assumed to be a function of

rotor inlet relative Mach number only since at design point the incidence is assumed

optimum. A curve of loss vs. rotor inlet relative Mach number is used with a scalar

to force the loss through the design point value. For off-design the incidence loss is

assumed to vary as (l-cosni) where n is determined from the NASA TASK II data of Ref. 4.

In order to indicate how different IG¥ positions are calculated, consider the

min-loss point on the 100% speed line. Assume an IGV setting of STPI= +20 ° is required.

The rotor exit relative flow angle (BETA2) is assumed to remain constant. The flow

coefficient and work coefficient are then calculated from the known value of ALPHA1 and

BETA1. A slight shift in the min-loss value of BETA1 and IGV position has been observed

in the data and is applied as a correction to BETA1 before the calculation is made.

The rotor continuity iteration to determine the axial valocity ratio across the

rotor is the key iteration in the program. The results of this iteration together with

the known flow angles sets the work coefficient at min-loss.

To determine the off-backbone characteristics, the angles ALPHA1 and BETA2 are

assumed equal to their min-loss values at the selected speed. A value of the work

coefficient is then chosen and the rotor continuity iteration carried out. The stator

and IGV losses are then added to obtain the stage performance.

23

_F _C_?_, :_i,:_ -:

7.2 Discussion of Variable Geometry Options for Axial Flow Fans

7.2.1 Variable Inlet Guide Vane (VIGV) Option

The VIGV option can be used to generate a set of off-design performance maps

for a user selected design point and set of IGV angles (i.e., STPI). The design

point is assumed to be at a zero value of STPI. The VIGV are assumed to be of the

type tested in the NASA TASK II program (Ref. 4), i.e., of a flap-type as sketched

in Figure 4. Since the IGV leading edge does not move, no IGV incidence loss is in-

cluded in the stage loss calculation. The inlet flow angle (ALPRAI) is somewhat less

than the IGV angle (STPI). As currently set the ratio of ALPHAI to STPI is about

0.775, as determined from the data of Ref. 4.

The nature of the flow modulation produced by the VIGV's is illustrated in

Figure 4. Let the nominal IGV setting represent the design point. Then at the same

speed and rotor incidence angle, the closed position results in a smaller value of

inlet axial velocity and, therefore, a smaller flow. A similar line of reasoning

leads to the conclusions that a negative IGV setting results in a flow increase.

The above conclusions can be made somewhat clearer and more quantative by

referring to the stage characteristlc sketch shown in Figure 5. The fan stage

characteristic can be expressed in either of the following two ways.

(1)

,

absolute inlet angle _

relative inlet angle

relative exit angle

where

2d

Positive IGV Nominal IGV Negative IGV'

u u

u 11 r

IGV

u

Rotor

Stator

Figure 4. Vector Diagram for Variable Inlet Guide Vanes (VIGV)

at Constant Rotor Incidence and Deviation Angle.

25

OF POOR QUAL[i_

O

n

,-4

2.0

=

q_

O

O

1.01

! I I

Min-Loss Locus

81 = 61.6 °

0 I0 0. i .5 2.0

STPI = +40 ° +20 ° 0 ° _I0 ° -20 °

I

m

Flow Coefficient

_1 = czl/u1

Figure 5. Stage Characteristics for VIGV Axial-Flow Fan.

26

If the axial velocity ratio (Cz2/Czl) and the exit flow angle are assumedto be con-stant, then equation one is a straight line passing through two (2) when the flow

coefficient equals zero. A series of these lines for different values of STPI

(ALPHA1= 0.775 x STPI) are shownin Figure 5. Also shownin Figure 5 is a line of

constant incidence angle passing through the design point (as given by equation 2).

The locus of the min-loss point on the 100%speed line,as generated by the programs,has also been indicated in the figure. It can be seen from Figure 5 that the min-loss

locus closely follows a line of constant rotor incidence angle. The changing flow

coefficient explains the flow modulation observed. Parametric mapsgenerated for

the NASATASKII VIGV Comparison (Ref. 4) are shownin Figures 6 thru 9. Onenegativeangle mapwas generated from the program in order to show the basic trends. Test data

is reported in (Ref. 4) includes three positive IGV positions (O°, 20° , and 40°) andno negative IGV settings.

The test data of Reference 4 was comparedwith the program results along the

min-loss locus. These comparison plots are shownin Figure i0, ii and 12. As can be

seen from the plots, as the IGV are closed, both the flow and the pressure rise de-

crease. In general, the agreement between the map and the test data is quite good.

All of the trends in the data are correctly predicted by the program.

7.2.2 Variable Pitch Rotor (VPF) Option

The VPF option can be used to generate a set of off-design performance maps

for a user selected design point and set of rotor pitch angles (i.e., ROT1). As with

the VIGV option, the design point is assumed to be at a zero value of ROT1. IGV are

assumed to be absent in this option.

The nature of the flow modulation produced by the VPF is illustrated in Figure

13. Let the nominal pitch setting represent the design point. Then at the same speed

and zero incidence angle the positive pitch (i.e., rotor closing) has a smaller value

of axial velocity than the nominal pitch. This results in less flow as the rotor is

closed.

As with VIGV, the same conclusions follow from the stage characteristic. This

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follows zero rotor incidence angle. The relative flow angle corresponding to zero

incidence is changed by varying the pitch of the rotor. Note that the min-loss locus

is nearly horizontal for the VPF while for the VIGV's the locus sloped upward from

the origin.

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• ,- +.......... _ ,..4 ......... +. + .;.+ -., + .+...._. - + ........................ _..+--.¢.-..... +.... : +.,... 4+.... +...;. : , , + • : . , +...r-+.,, <-r.-++-.---+-,.,..+-- ,---.............+. ,

I +- _ -t"l"e +-{ -+ _-+-t- ....... ÷ "- -i"f" _" -t ............ L_-.t-

[ I ; I: 'I+ ''t i .................................................................................................., ' L I : : { ' " : ' _ L : I I ' ] : I ; _ 0

.....- --. r...........rT :-" t .a. T TT ' ;"T " T + 27 .: -.+...... t ....... r - ....... =: :r bt -- , r-+_ ', t _ _ ' t"'::

............... _.+ + +.++. + ........+..+...,.++ .._ +.++.....+ . p.+ ..... - .. ........ +......_+_" ........ , +' ' i ' , ! { : : : t : : " " " ' ' I

........... _--+'+'-.--÷ ' "r", ...... +-+"'+ ","" -"! t +'' , ......... [" ................ I"-":"+

...... +.+ .+--+-.i .-_.............. 4--..._..÷-. + ............. _.-+, .............. I .+ _._ [ +_. + .. +...+.+_..,_.,.+....+..L_+. +r'-, ....... _..._..._. .____-L. .I._ ...... k- + " ÷"" t" a !-: "_........ -T

•;. _- 4+..-{..; a-...+ +..+a. --+---._ .4- J--_.-4- .÷ + +--.., ; . ..a +.+ ........ ,.+.. +-... + I=1• _ , t , , L t : : : ' I : _ .... I I _{_J {_

. ' ' I { .... _ ; ;2_I_ ::+ T : ? :] +.+, +..'. :..I._ +...+.=.,_.;..+.... ;-.+--+---'+ - .. .......... +. -...................... _............. _I.................. + ................ +--+11 I+ "+ Tit p I+ + I ....... t t "T' : + i'_--..... :.-+-_- i-+-_. Z££T<.+.-]:.+........ +-+............. ,...............+ .............. , -, ........

........+ ................+: t+-: +F+ 1:++f+, ,.++' ' }--+-.]-++-}.,.' .............i.. -i- .... ;+: ....... _......... . r,,L .......... e ; ......... +.-, +- -.+---+......... ,..+ ........ , +. +............... *.+ ........... 7.-? + .f .- ÷

;?++t-t + -:+t-,++tt?it.:+f,+-/_ "-: ................:i ....._.......................................... +.................. <_....7: : : ..... " : + ; .... -.... +........................../ r +........... +................ 1:[: • ....:2:::.:: ; + _• ....... + _ u.I

.. ; + " _.2.; ..........• +.... t" .i....... +.4.... +..+ , .+..+...... I--, , i i ' } ' i , ] _ _ , + rj _ ' + {.J

..................... +-4 .4--_........... _..+--I..+ _..... ........ :.= ..... +........ Iii...... : ................ ; .4.,. -...+..+ ........ +,.++.-L ' _++_ .......... I ..... + U ................ :

.......... I . _ _ _+- - 4. .+ ,-,...._.++ : . L '_ I- tt.-!--- 4 .+ - ; i.+ +- I_ .... +. a ..... + I_

:- +--].'--+--;-r++-i-t+-f-+ +f: t:-+++ t:a.,-,:-,_ ....: _ : --: g '_

....... P++I++I++I +-+; .I -, +-+.]...,--+-; .............+._;-+4,--:;]il .....+' ........................ --o..... _ +':'_ ,+..-!-;,. _+.++........... ,-...i ._. ++-*-+ ......._ ........ ........0 +.! I i i]+ - , (..)........... 3++ ......... +.+,.....2.+.. a•+ _.....,._+.2 .,._ ,. : .... • .... , _

-+-+ :- : ........ . +...+. + ]+++-+ _-,--+-+ ....... +

:+:,:+.,.,+++;;.........+++..........++.:_.... ; ..L . ...; +. +_......... i... 4- • -.+-.'.--i . _.-+. J...- ;. +.,i ..... , ......... -I. +4-_-+.-4-.++- ................ +--++-:_$ _ .....

: : : +?! "i_ t '-"!- .......i_! :,- '

i :!::I::!.' t:.::,',2. :!:::2:ii: .°_

<i,;

.... t+! ....4-4-4- ...... L4-1-.;-L.;..' .;-4-i- -:--i 4.+;-4 ;. +....... _";_i t _ + -_

-+++---+--+-+-.-+++'-.+,+. i::ii................ I-++-' -- t--t .......... +.. _+....+- ....... t..., - +..a ...... +. +., - +.-..+. + ............-I-+i----r-t--I-..--t_+-- H-4 c .:-t +.-!4-t i ---+*.'i....... +-,-+

0"_ 9"|

OIIU_ _ASS3_d

P0

0

+

II

=m

o

m0_

rD

Nm

m

..4

31

OF POOR Q J/_LF_ ,

G-,-4

ov-t_._

cJ_J

o

1.5I l I 1

STPI W/WD = 223 pps1.4

O O° PQPD = 1.65

1.3 -- _] 20o -- EFFD = 0.834

_o40 °

i. 2 Map _I.i

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

00.1

00 0.i 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 i.i

Corrected Speed, percent

Figure i0. Flow Variation Along Min-Loss Locus (Single StageVIGV Fan).

32

0O_

<_

<S

G-r..I

m

Q.I

m

1.5I i I

i. 4 - STPI

O 0 ° W/WD = 223 pps

1.3 [-] 20 ° PQPD = 1.65

<> 40 ° EFFD = 0.834Map

1.2 ----- i Ii

i.i

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.i

)

I

I

/

0

0 0.i 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 i.i

Corrected Speed, percent

Figure ii. Pressure Rise Variation Along Min-Loss Locus (Single

Stage VIGV Fan).

33

r.:1

r.:1

G

>,

=

u_

r..=1

1.5

1.3

i.i

0.9

0.7

0.5

' ' I ISTPI W/WD = 223 pps

© 0=

O 20° PQPD = 1.65

-- <> 40 o EFFD = 0.834

-- Map

0.3

0.i

0 0.i 0.2 0,3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Corrected Flow, percent

i.i

Figure 12. Efficiency Variation Along Min-Loss Locus (Single

Stage VIGV Fan).

34

_.4:..___. _

Positive Pitch Nominal Pitch Negative Pitch

w c

W//u

U

//

u

Rotor

Stator

Figure 13. Vector Diagr_ for Variable Pitch Rotor (VPF).

35

_no

eq

eq

ii

4J=

o

u_0o

o

I0.5

ROTI = +5 ° 0 ° -5 °

Min-Loss Locus

I

m

u

Ir

2.0

Flow Coefficient

_1 = CzI/UI

Figure 14. Stage Characteristics for VPF.

36

7.3 Discussion of Centrifugal Compressor Option

OR'C_,_._.L p?__._,_,

OF PO0_:: QUA!.h_y

7.3.1 Fixed Geometry Centrifugal Compressors

The centrifugal compressor option can be used to generate a set of off-design

performance maps for a user selected design point. The default settings assume a

geometry consisting of an impellor followed by a radial diffuser. The inlet swirl

angle is assumed to be zero and no provision is made for inlet guide vane loss.

The test data of Reference 5 was compared with the program results for the

centrifugal compressor default case along the min-loss locus. These comparison plots

are shown in Figure 15, 16, and 17. In general, the agreement between the map and the

test data is fairly good. All of the trends in the data are correctly predicted by the

program.

7.3.2 Variable Inlet Guide Vanes (VIGV)

Centrifugal compressors frequently have a substantial degree of inlet swirl.

This swirl may result from the presence of an upstream axial compressor, or from the

presence of inlet guide vanes. In order to account for inlet swirl at the design point,

the program has provision for user selection of the design point inlet guide vane

position (STPID). The turning effectiveness of the IGV is assumed to 0.775 (i.e.,

ANGAI = 0.775 x STPI). No loss is charged to the IGV.

A variable inlet guide vane option (VIGV) has been provided for the centri-

fugal compressor just as for the axial flow fan. The most significant difference

between the axial and centrifugal VIGV options is that no loss is charged to the inlet

guide vanes in the latter case.

The nature of the flow modulation produced by the VIGV's for the centrifugal

machine is somewhat different from that for an axial machine. This can be made clear

by comparing the stage characteristics for the VIGV centrifugal compressor with those

of the axial flow fan which was shown in Figure 5.

The stage characteristic for a centrifugal compressor can be expressed in

either of the following two ways;

,?,

3?

o"

:30

Q;

o

1.2

1.0

0.8

0.6

0.4

I

W/WD = 5.5 pps

PQPD = 4.3

EFFD = 0.76

0.2

00 0.I

Figure 15.

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Corrected Speed, percent

Flow Variation Along Min-Loss Line (.Centrifugal

Compressor).

i.i

38

o

<:_

<_

o"

{.I)

1.2

1.O P

0.8

0.6

0.4

0.2

00

I I I (3

W/WD = 5.5 pps 7

0.I 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 i.i

Corrected Speed, percent

Figure 16. Pressure Rise Variation Along Min-Loss Locus

(Centrifugal Compressor).

39

OF POOR QUALI]_'(

O

4.1

>-,U

tj

1.2

1.0

0.8

0.6

0.4

0.2

W/WD = 5.5 pps

PQPD = 4.3

EFFD = 0.76

0 0.2 0.4 0.6 0.8 1.0 1.2

Corrected Flow, percent

Figure 17. Efficiency Variation Along Min-Loss Locus (Centrifugal

Compressor).

40

Equations three and four reduce to equations one and two if the ratio of the inlet

to exit radii is set equal to unity.

If the axial velocity ratio (Cz2/Czl) and the exit flow angle are assumedto

be constant, then equation three is a straight line passing through two (2) when the

flow coefficient equals zero. A series of these lines for different values of STPI

(ALPHA1= 0.775 x STPI) are shown in Figure 18. Also shown in Figure 18 is a line of

constant incidence angle passing through the design point (as given by equation 4).

The locus of the min-loss point on the 100%speed line has also been indicated in the

figure. It can be seen from Figure 18that the min-loss locus closely follows a line

of constant rotor incidence angle. The flow modulation results from the change inflow coefficient along this locus.

Note that the value of the min-loss work coefficient increases as the flow coefficient

is reduced. This behavior contrast with that of the VIGV axial flow fan shownin

Figure 5 , where a reduction in the value of the min-loss flow coefficient resulted

in a reduction in the work coefficient. The difference is due to the presence of theinlet-to-exit radius ratio in equations three and four.

Performance mapswere generated for the VIGV centrifugal compressor reported

in Reference 6 . In this reference test data was reported for three IGV positions(-13 ° , 0°, 40°). The data as reported gives only the impeller performance. In order to

generate a map of the impeller performance the program source was edited to eliminate

the diffusser loss. The test data of Reference 6 was comparedwith the program resultsalong the min-loss locus. These comparison plots are shown in Figures 19, 20, and 21.

As can be seen from the plots as the IGV are closed, the flow is reduced and the impelle_

pressure rise increases. The agreement between the mapand the test data is fairly good.

According to Reference 6 , an additional loss of about 2.5% in impeller efficiency atthe STPI = 40° position occurred as a result of inlet flow distortion.

41

ORIGINAL rl-,_,;.OF POOR QUALITY

i-jO

¢,,Ic'q

v

II

=

rj

OL)

O

2.0

1.5

1.0

0.5

I R2/R I -- 2.225

Min-Loss Locus

o

STPI = 40 °

0.5 1.0 1.5

Flow Coefficient, _i = CzI/UI

2.0

Figure 18. Stage Characteristic for VIGV

(Centrifugal Compressor).

42

ORIGINAL Pf;,GE {:_

OF POOR QUALITY

1.2

o.i.I

o

0

00

0o

1.0

0.8

0.6

0.4

0.2

0

Inlet Pressure

[] +40 °

O 0 °

<> -13 °

------ Map

l<>

W/WD = 1.4 pps

PQPD = 6.1

EFFD = 0.87

0 20 40 60 80

Corrected Speed, percent

i00

Figure 19. Flow Variation Along Min-Loss Locus (VIGV

Centrifugal Compressor-Impeller Only).

43

1.2

1.O --

G.,iI

0.6

0.4

0.2

0

0

Inlet Pressure

_] +40 ° i

0 0° C

O -13° t

0 °

3 °

J_J W/WD = 1.4 pps

J20 40 60 80 i00

Corrected Speed, percent

Figure 20. Pressure Rise Variation Along Min-Loss Locus

(VIGV Centrifugal Compressor-Impeller Only).

44

OF POOI_ eL; _,Li',_'

o".,'-I,,l,,J

(,J

u,.-I

1.5

1.3

i.i

0.9

0.7

0.5

I I

Inlet Pressure

[] +40 °

© 0°

<> -13 =

-- Map

+40 °

-_ 00 -13°

-- O

/ I_ 2.5% IGV Loss Due to

Inlet Distortion

IW/WD = 1.4 pps

PQPD = 6.1EFFD = 0.87

0 0.i

Figure 21.

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Corrected Flow, percent

Efficiency Variation Along Min-Loss Line (VIDV

Centrifugal Compressor-Impeller Only).

0

-<>

i.i

45

REFERENCES

io

o

.

*

,

a

Fishbach, Laurence H., and Caddy, Michael J., "NNEP: The Navy-NASA

Engine Program," NASA TM X-71857, 1975.

Fishbach, Laurence H., "Konfig and Rekonfig - Two Interactive Pre-

processing Programs to the NAVY/NASA Engine Program (NNEP)",

NASA TMX-82636, May 1981.

Converse, G.L. and Giffin, R.G., "Extended Parametric Representation

of Compressor Fans and Turbines", CMGEN User's Manual.

Bilwakesh, K.R., "Evaluation of Range and Distortion Tolerance for High

Mach Number Transonic Fan Stages, Task II Stage Data and Performance

Report for Undistorted Inlet Flow Testing," NASA CR-72787, January, 1971.

Rogers, C., "Typical Performance Characteristics for Gas Turbine Radial

Compressors," Journal of Engineering for Power, Trans. ASME, Series A,

Vol. 86., April 1964.

Rogers, C., "Impeller Stalling as Influenced by Diffusion Limitations,"

Journal of Fluids Engineering, Trans. ASME, March 1977.

46

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Ma% 1 Stop

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