NASA/CR-2001-211056

An

for Mixedof Propulsion

Flow Nozzle

at Takeoff

& Materials, Inc., Hampton, Virginia

2001

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NASA/CR-2001-211056

Computational Analyses of PropulsionAeroacoustics for Mixed Flow Nozzle

Pylon Installation at Takeoff

Steven J. Massey

Eagle Aeronautics, Inc., Hampton, Virginia

Kenrick A. Waithe

Analytical Services & Materials, Inc., Hampton, Virginia

National Aeronautics and

Space Administration

Langley Research Center

Hampton, Virginia 23681-2199

Prepared for Langley Research Centerunder Purchase Order L-13395

September 2001

Available from:

NASA Center for AeroSpace Information (CASI)

7121 Standard Drive

Hanover, MD 21076-1320

(301) 621-0390

National Technical Information Service (NTIS)

5285 Port Royal Road

Springfield, VA 22161-2171

(703) 605-6000

Computational Analyses of Propulsion Aeroacoustics for

Mixed Flow Nozzle Pylon Installation at Takeoff

Steven J. Massey

Eagle Aeronautics, Inc.

Hampton, VA

Kenrick A. Waithe

Analytical Services and Materials, Inc.

Hampton, VA

June 21, 2001

1 Introduction

The objective of this task is to perform CFD analyses of a set of baseline and noise suppression

mixed flow nozzles with and without a pylon installation. This paper presents the full

CFD results from which the principal investigators of the study have recently published a

conference paper, Thomas et al. [1]. The five model configurations are as follows: a baseline

core/fan dual-stream nozzle with an external plug, a chevron mixer nozzle with a peak on the

symmetry plane with external plug, both of the above nozzles with an installed bifurcating

pylon and lastly a clocked chevron mixer nozzle such that a trough is aligned with the center

of the pylon. All grids cover 180 ° of the nozzle. The grids were constructed by GeoLab at

LaRC under a separate task. Since the cases were solved using two schemes, time marching

for the nozzle region and space marching for the far-field plume, the cell counts for the two

regions for each case are given separately in Table 1. In this study the flight takeoff (TKO)

flow conditions are solved on all models, see Table 2.

Table 1: Grid Size in Ceils

Time Marched Space Marched

Case Geometry Nozzle Plume Total

1 Round Nozzle 4,083,072 1,797,120 5,880,192

2 Round Nozzle w/Pylon 7,805,440 3,594,240 11,399,680

3 Chevron Nozzle 10,125,312 3,594,240 13.719,552

4 Chevron Tip under Pylon 12,620,096 3,594,240 16,214,336

5 Chevron Trough under Pylon 13,383,744 3,594,240 16,977,984

Table 2: Flow condition definitions.

Flow Condition Mach Pt[psi] Tt[R] FPR CPR Fan Tt[R] Core Tt[R]Takeoff (TKO) 0.28 14.7 530. 1.75 1.56 647. 1491.

2 Numerical Method

The fluid flow is simulated by solving the asymptotically steady, compressible, Reynolds-

averaged Navier-Stokes equations using an implicit, up-wind, flux-difference splitting finite

volume scheme and standard two equation k-c turbulence model with a linear stress repre-

sentation. All computations are performed using the multiblock, parallel, structured code

PAB3D [2]. Solutions are obtained using the flux difference splitting scheme of Roe, un-

coupled viscosity in the normal and circumferential directions, linear k-c turbulence model,

and a 2-factor scheme for the approximation of implicit terms. Grid sequencing is used to

accelerate convergence by solving 1/4 then 1/2 of the grid in each of the three computational

directions. The general solution procedure followed is to solve the region near the nozzle via

time marching, then solve the plume blocks via space marching, then finally run a compara-

tively small number of time marching iterations on the plume blocks and adjacent upstream

blocks in order to smooth any inflections at the time/space marching block boundary. Wall

clock run-time using four Compaq Alpha 500 MHz machines in parallel is (depending on grid

size) approximately 50 to 150 hours for time marching of the nozzle and nearby plume, 3-6

hours to space march the plume, and 4-8 hours to smooth out the solution by time marching

the plume. The final plume time marching is optional since the space marched solution is

already well converged. Due to the large size of these cases, they will scale very efficiently

to the larger clusters as they become available.

3 Results

In this study, the effects of geometry changes are sought on the precursors of noise, such as

turbulence and vorticity. It is hoped that any geometry change will not have a significant

effect on the performance of the nozzle. Grids and flooded solution contours are presented

in Figures 1-34 for the five cases identified in Table 1. Pylon flow topology is shown in

Figures 35 and 36. Model comparisons for axial variation of mass averaged quantities with

integration lower limits set to 100.5% of freestream Tt and 100.5% of fan Tt are plotted

in Figures 37 and 38 respectively. Mass averaged quantities are calculated at each axial

station by integrating over the area that contains flow above the chosen total temperature,

for example,

ka_ fA kpu dAfdpu dA (1)

with integration only performed over areas where

T__>1.005T_ or T_F_. (2)

Non-dimensional forms of total temperature and turbulence kinetic energy are shown in

Figures 39 and 40 respectively. The non-dimensional expressions are identical to those

published by Kenzakowski et al. [3] and are defined as follows:

Non-dimensional Average Total Temperature -

Average Turbulence Intensity -

fA Cpu dA

fA pu dA

fA _qqpU dA

fA pu dA

(3)

(4)

where

z

Tt -- TtFA N

TtCORE --TtFAN

with integration only performed over areas where

(5)

0.005_<¢ _<1. (6)

The integrations were implemented using a combination of Tecplot scripts and Fortran code

written by the authors specifically for this task. Lastly, axial variation of maximum total

temperature and specific turbulence kinetic energy are plotted in Figures 41 and 42 respec-

tively.

3.1 Case Round Nozzle

The round nozzle case is the baseline case from which the effects of the pylon and chevrons

will be evaluated. Although the geometry is axisymmetric, the case is still run as a 3-D half

plane with the same grid topology as the other cases, Figure 1. A typical maximum flow

vector residual history is shown in Figure 2, where the spikes highlight the change in grid

sequencing from 444 to 222 to 111. Because the round case is coarser than the other cases,

residual dropped only by a little more than three orders of magnitude. Finer cases typically

drop by more than four.

Contours of Mach number, Pt and Tt, shown in Figures 3-5, depict a clean symmetric

solution, despite the many block boundaries and the fact that the solution was space marched

beyond x - 13.7 core diameters. Note, in all cases length is in terms of the round nozzle

core diameter with the origin at the fan exit. For all Tt plots the contours are cutoff below

100.5% of freestream. Vertical cross-flow planes at x - 2, 4, 8, 16 core diameters, Figures 6

and 7, indicate a well developed solution with no asymmetry except for the log vorticity

magnitude. In _ is very sensitive to any solution fluctuations as well as grid quality.

3.2 Case Round Nozzle w/ Pylon

Figure 8 depicts the pylon and nozzle grid surfaces in black against the blue symmetry plane.

Close-up rotated views of the pylon/nozzle interface are shown in Figure 9. Symmetry plane

plots, Figures 10-12, show the strong vertical influence of the pylon (and lower bifurcator)

on the jet flow. Cross-flow plots, Figures 13-14, clarify the effect by showing the location

of the pylon in the flow and its azimuthal influence. It is clear from the pressure and total

temperature plots, that the pylon shields the top portion of the core flow from the high

pressure fan flow. This allows the core flow to follow the bottom contour of the pylon, which

due to its upward curvature imparts significant upward momentum. In comparison to the

baseline round case, a large increase of k can be seen in the x - 8 plane. As noise is a

function of turbulence, this peak is a likely source for noise.

3.3 Case 3_ Chevron Nozzle

Symmetry plane views show a well developed and vertically symmetric solution for the

chevron case, Figures 16-18. Because of the star-like cross-flow pattern caused by the

chevrons, contours on the symmetry plane can be misleading. An example of this is the

apparent source of Tt near the x - 6 station, which is simply the cross-flow lobe moving

closer to the symmetry plane. Cross-flow images, Figures 19-20 are all very symmetric and

indicate that future studies without a pylon may be carried out on 1/8 sector rather than the

present 1/2. The chevrons mix the flow very well while at the same time reducing average

and peak specific turbulence kinetic energy levels, Figures 37 and 42.

3.4 Case 4_ Chevron Tip under Pylon

In this case, the pylon was added to the chevron geometry, Figure 21. Close-up rotated views

of the pylon/chevron interface are shown in Figure 22. The introduction of the pylon to the

chevron jet flow produces the same effect as on the round jet, Figures 23-25. The new feature

is the top lobe of core flow is now drawn into the pylon, Figures 26-27, which produces a

strong attachment line coupled with a spiral separation on each side of the bottom the pylon,

Figure 35.

3.5 Case 5_ Chevron Trough under Pylon

The final case is constructed by rotating the chevrons such that the trough lies directly

under the center of the pylon, Figures 28-29. Moving the trough under the pylon has the

very beneficial effect of splitting a single cross-flow plume on the pylon, Figure 33, which

reduces the energy available to the pylon boundary layer and fan shear layer and thus results

in much lower specific turbulence kinetic energy levels, Figure 34. Separation is also reduced

and moved to the sharp outer edge of the pylon, Figure 36. A strong attachment line is

also observed in close alignment with the chevron edge on the bottom of the pylon. For

reference, the round nozzle with pylon case did not incur any flow separation on the pylon

and both chevron with pylon cases did not have any further flow topology features outside

the boundaries of the figures shown, Figures 35 and 36.

3.6 Axial Distributions

With the exception of turbulence kinetic energy and vorticity, mass averaged quantities of

the full jet using a temperature integration lower limit of 100.5% of Ttoo are largely diluted

by the inclusion of fan flow, Figure 37. To better isolate the mixing between the fan and

core flows, averages are taken using a temperature integration lower limit of 100.5% of TtFAN,

Figure 38. From the latter set of averages, and the non-dimensional averages, Figures 39

and 40, it is clear that the core chevrons significantly enhance mixing while the pylon itself

providesaslight increasein mixing for round and chevroncases.In terms of peak turbulencekinetic energy,Figure 42, the clockedchevronis muchlower than the other pylon cases,whileslightly higher than the no-pylon cases.

4 Concluding Remarks

In general the cases ran very well. Techniques have been developed to extract quantitative

characterizations of the jet flows. Further study is required to refine expressions which are

indicative of noise and mate these with rigorous noise prediction models. It is concluded

that the clocked chevron with pylon case achieves the most optimal levels of average and

peak turbulence kinetic energy and vorticity and therefore is expected to be the quietest of

the five configurations tested.

The authors wish to gratefully acknowledge the Configuration Aerodynamics Branch of

LaRC for the use of their Alpha clusters to complete the cases in this study. All data and

post processing files and scripts are included in the deliverables on CD-ROM.

References

[1] Thomas, R. H., Kinzie, K. W., and Pao, S. P., "Computational Analysis of a Pylon-

Chevron Core Nozzle Interaction," AIAA Paper 2001-2185, 2001.

[2] Abdol-Hamid, K. S., "Development of Three-Dimensional Code for the Analysis of Jet

Mixing Problem," NASA CR 4200, 1988.

[3] Kenzakowski, D. C., Shipman, J., and Dash, S. M., "Turbulence Model Study of Lab-

oratory Jets with Mixing Enhancements for Noise Reduction," AIAA Paper 2000-0219,2000.

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in blue.

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Figure 12: Case 2, Round Nozzle w/Pylon: Total Temperature [K] contours.

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from the fan exit.

12

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Log Vorticity Magnitude [l/s] contours at stream-wise stations x = 2, 4, 8, 16 core diameters,

starting from the fan exit.

13

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fan exit.

16

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Figure 20' Case 3, Chevron Nozzle: Specific Turbulence Kinetic Energy [kJ/kg] and Log

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starting from the fan exit.

17

Figure 21: Case 4, Chevron Tip under Pylon: grid close-up view, with symmetry planeshown in blue.

Figure 22: Case 4, Chevron Tip under Pylon: pylon grid interface views, with symmetry

plane shown in blue.

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Figure 24: Case 4, Chevron Tip under Pylon: Total Pressure [kPa] contours.

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989985

;:',_X2_E7

)43 Ou

")4_0

X=4D o

I 0 05 oo ,3,5 10 15

Z/D c

X=4D o

Z/D c

7_2

7E4

6,964

60s5_5

5_7_j

IIST_SS_

SCO

X=8D c

)S9

)S598)

97'3371366

)62

9.%

_43

_S9 _-

_25

X=8D c

I.s o o_ ,., ,z,.b /o 1_

Z/D c

X=8D c

15

Z/D c

X= 16D c X=16D c X=16D c

)S9

)S598)

97'3371

366)62

9.%

_43

_S9 _-

_25

I.s o o_ ,., ,z,.b /o 1_

Z/D c

Figure 26: Case 4, Chevron Tip under Pylon: Mach number, Total Pressure[kPa] and Total

Temperature [K] contours at stream-wise stations x = 2, 4, 8, 16 core diameters, starting

from the fan exit.

20

k [kJ/kg]X=2D o

[I/s]X=2D o

2_ 0 I 5 I 0 05 00 c 5 c 5 2 c

Z/D c

25 2,, 5 10 ,, oo 05 IC 15 2,, 25

7JD c

X=4D o X=4D o

2_ 0 I 5 I 0 05 00 c 5 c 5 2 c

Z/D c

25 2,, 5 I0 ,, oo o5 IC 15 2,, 25

7JD c

X=8D c X=8D c

292O /L /0 Ob O0 C.b C .b 2.6

Z/De

2b 2.'3' .b /0 0.s O00.L 1.6 /L 2.'3' 2.b

Z/D c

X= 16D c X= 16D c

£b 2.'3' .b /0 0.s O00.L 1.6 /L 2.'3' 2.b

Z/D c

Figure 27: Case 4, Chevron Tip under Pylon: Specific Turbulence Kinetic Energy [kJ/kg] and

Log Vorticity Magnitude [1/s] contours at stream-wise stations z = 2, 4, 8, 16 core diameters,

starting from the fan exit.

21

Figure 28: Case5, ChevronTrough under Pylon: grid close-upview, with symmetry planeshownin blue.

Figure 29: Case5, ChevronTrough under Pylon: pylon grid interfaceviews,with symmetryplaneshownin blue.

22

5.0 10.0 15.0 20.0 25.0 30.0

XtD c

4-19_ 377

ss5i_i_i_i_i_i_i_i_i_i_i_i292

250

_ 2076522

80

Figure 30: Case 5, Chevron Trough under PylonAxial Velocity Ira/s] contours.

68

595142342517O800

5.0

rj

0.0

-5,05. 0

819::::::::::::::::::::::754

6a9iiiiiiiiii@i_i624

5604-95

4-303653OO0.0 5.0 10.0 15.0 20.0 25.0 30.0

XID c

Figure 32' Case 5, Chevron Trough under Pylon: Total Temperature [K] contours.

23

MX=2D c

)S9)S5

98)97'S

371)66

)62

9.%_48

ao

_25

[kPa]X=2D o

I 0 05 oo ,,5 10 15

Z/D c

1.5

I .C

,, 5

,, C

,;,.5

I .C

[iqX=2D o

1"51 0 05 8,8, ,,5 I0 15

Z/D c

7_2

7_4

6,964

60s5E5

5_7

II

ST_SS_

SCO

X=4D o

989985

;:',_X2

)43 Ou

")4_0

X=4D o

I 0 05 oo ,3,5 10 15

Z/D c

X=4D o

Z/D c

7_2

7_4

6,964

60s5E5

5_7_j

IIST_SS_

SCO

X=8D c

)S9

)S598)

97'3371366

)62

9.%

_43

_S9 _-

_25

X=BD c

I.s o o_ ,., ,z,.b /o 1_

Z/D c

X=BD c

15

Z/D c

X= 16D c X=16D c X=16D c

)S9

)S598)

97'3371

366)62

9.%

_43

_S9 _-

_25

I.s o o_ ,., ,z,.b /o 1_

Z/D c

Figure 33' Case 5, Chevron Trough under Pylon: Mach number, Total Pressure[kPa] and To-

tal Temperature [K] contours at stream-wise stations x = 2, 4, 8, 16 core diameters, starting

from the fan exit.

24

k [kJ/kg]X=2D o

[I/s]X=2D o

2_ 0 I 5 I 0 05 00 c 5 c 5 2 c

Z/D c

25 2,, 5 10 ,, oo 05 IC 15 2,, 25

7JD c

X=4D o X=4D o

2_ 0 I 5 I 0 05 00 c 5 c 5 2 c

Z/D c

25 2,, 5 I0 ,, oo o5 IC 15 2,, 25

7JD c

X=8D c X=8D c

292O /L /0 Ob O0 C.b C .b 2.6

Z/De

2b 2.'3' .b /0 0.s O00.L 1.6 /L 2.'3' 2.b

Z/D c

X= 16D c X= 16D c

£b 2.'3' .b /0 0.s O00.L 1.6 /L 2.'3' 2.b

Z/D c

Figure 34: Case 5, Chevron Trough under Pylon: Specific Turbulence Kinetic Energy [kJ/kg]

and Log Vorticity Magnitude [l/s] contours at stream-wise stations z = 2, 4, 8, 16 core di-

ameters, starting from the fan exit.

25

Figure 35: Case 4, Chevron Tip under Pylon: Pylon surface streamlines. Core nozzle shownin red.

Figure 36: Case 5, Chevron Trough under Pylon: Pylon surface streamlines. Core nozzleshown in red.

26

0.20

0.18

0.16

0.14

E0.12¢=.¢ 0.10

0.08

0.06

0.04

0.02

0.00

J .... I .... I .... I .... I .... I ....

_.._._.._i R°und w/Pylo n _z/_

..... _ ..... Chevron //._/_.:_'# /

....... 4- ....... Oh ..... / Pylon _/{_'/

Clocked Chevron w/Pylon ,_,_._,

/f

_e

• .... i .... i ..........5 10 '1;' '2'0'X/D c

o

7.0.1 .... i .... i .... i .... i .... i ....

I ...... ! ..... Round

........_........Round w/Pylon6. 0

.... :3 .... Chevron , _

....... 4- ........ Chewon w/Pylon _,/&_"

5.0 + Clocked Chevron w/Pylon /

4.0

3.0

2.0

1.0,

5 '1'0' 'l'a" '2'0'X/D c

3OO

_' 280

260o.

Eo 240O

"_ 220

:= 200

180==_ 160

_ 140

120

' ' ' i .... i .... i .... i .... i ....

_4_ ----I---Round

- _ Round w/Pylon

'_'_f_ :--:-:-4.:--:-:-oOheeVrro°nnw/Pylon

_&, + Clocked Chevron w/Pylon

.... i .... i .... i .... i .... i ....

5 10 15 20 25 30

X/D c

45O

440:

_, 430420

E 410

I_ 400

¢= 390O

I- 380

370

36O

350

=E 340

330

320

310

4 .... I .... I .... I .... I .... I ....

----!--- Round

_" Round w/Pylon

_; - - - _ - - - Chevron

_. ....... -4 ....... Chevron w/Pylon

"_,_ _ Clocked Chevron w/Pylon

.... 5 .... 110 .... 115 .... 210 .... 215 .... 30

X/D c

,,i

==

1 12 _ ........ /_ _-I _ _: ............

11-1- ,j

o.9- .¢._--_',_

0.7 -- ." _x,o.o_°si/ .0.4 --1-- Round _t_

0.3 _"_ ;, Round w/Pylon

oI2_/ _- -. _h'ev_on w/Pylon

O.1 _ _ ClockedChevronw/Pylon

0 0 5 10 15 20 2=* I I I I 15 30

X/D c

11000

_.0000

_9000

_8000

.__7000o

6000O

> 5000

4000

_3000

2000

1000

.... i .... i .... i .... i .... i ....

...... 1 ..... Round

....... # ........ Round w/Pylon

..... 3 ...... Chevron

....... 4 ........ Chevron w/Pylon

Clocked Chevron w/Pylon

5 10 15 20 25 30

X/D c

Figure 37: Full Jet: Axial distribution of Jet Area [m2], Jet Mass, Mass Averaged Axial

Velocity [m/s], Total Temperature [K], Specific Turbulence Kinetic Energy [kJ/kg] and Log

Vorticity Magnitude [l/s].

27

0.014

0.012

0.010

E0.008

'_ 0.006 J

0.004

0.002

0.000 0

,,, j_

,.,

_J/,

//! t

/l"

¢,

--I--- Round

....... :?........ Round w/Pylon

...... _i ..... Chevron

....... 4- ....... Chevron w/Pylon

Clocked Chevron w� Pylon

5 10 15 20 25 30

X/D c

0.00

Round

Round w/Pylon

..... ?, .... Chevron

........ 4 ........ Chevron w/Pylon

Clocked Chevron w/Pylon

5 10 15 20 25

X/D c

30

o.

EOo

"6

===E

4OO

35O

3OO

25O

2OO

I , , , , I , , , , I , , , , I , , , , I , , , , I , , , ,

--1-- Round "_.

....... 4........ Chevron w/Pylon

Clocked Chevron w/Pylon

0.... ; .... 1'0.... 1;.... 2'0.... 2; _0X/D c

85O

800 I

750o.

E 700I--_ 650O

I- 600

> 55o

==m 500=E

450

400

35O

I , , , , I , , , , I , , , , I , , , , I , , , , I , , ,

----_--- Round- ;' Round w/Pylon

[ ::-:-:-4.:--:-:-oOheewWo°n n w/Pylon

_ + Clocked Chevron w/Pylon

• \'1

_, "X \

", \:\?,

i .... i ,

0 5 10 15 20 25

X/D c

30

_2.0

1.5,v,

_1.0

=E 0.5

!

/

...... I ...... Round

....... :_"........ Round w/Pylon

i .... !_ ..... Chevron

+ Chevron w/Pylon

i. + Clocked Chevron w/Pylor

0% ..... _.... 1'0.... 1'5.... 2'0.... 2'5.... 30X/D c

20000 1

...... 1 ...... Round

_17500 ........_........ Roundw/Pylon_'-- .... '_ .... Chevron

_15000 ---4--- Chevronw/PylonClocked Chevron w/Pylon=E

_,_,__12500 "',._o

o 10000

7500

m 5000

2500

00 5 10 15 20 25 30

×/D c

Figure 38: Core Jet: Axial distribution of Jet Area [m2], Jet Mass, Mass Averaged Axial

Velocity [m/s], Total Temperature [K], Specific Turbulence Kinetic Energy [kJ/kg] and Log

Vorticity Magnitude [1/s].

28

11

0.9

0.8

0.7E"o0.6

E 0.5

_,_0.4

0.3

0.2

0.1

0

J''' ' I'''' I'''' I''' ' I''' ' I ' ' '

--_ - -1- Round

..........._ ............ Round w/Pylon...... 3 ...... Chevron

----4---- Chevron w/Pylon

- '!_ _ Clocked Chevron w/ Pylon

i i i

0 5 10 X15/Dc 20 25- 30

Figure 39: Mass averaged non-dimensional Total Temperature decay

0.200

0.1 75

0.150

E"D 0.125

E"D 0.100O"

_0.075

0.050

J

0.0251

0.000

'''' I'''' I'''' I''' ' I''' ' I ' ' ' '

/ 3

,/Z / / -- -1- Round

._/ / ...........2 ............ Round w/Pylon

:_ j 4 ...... 3 ....... Chevron,, --4--- Chevron w/Pylon

- _ _ Clocked Chevron w/Pylon

l..h , , , I , , , , I , , , , I , , , , I , , , , I , , , ,

o 3o

Figure 40: Mass averaged non-dimensional Turbulence Intensity decay

29

8OO

,--, 7005.Eo

--_ 600

OI'-x

500=E

4OO

\\ i', _

.........1 ........ Round \\'._,_"Round w/Pylon--"-'_

........(,".,........ Chevron" _'_._. \

Chevron w/Pylon "_'_.

, ,0 5 10 15 20 25 30

X/D c

Figure 41: Axial distribution of maximum Total Temperature [K]

11

10

9

ui 7,_ 6

5_ 4

_ 3

2

1

'' ' I''' ' I''' ' I''' ' I''' ' I''' '_-

, -1- - Round

Round w/Pylon....... _._....... Chevron

Chevron w/PylonClocked Chevron w/ Pylon -

.................... -

,,,, I,,, , I,,, , I,,,, I,,, , I , , , ,

0 5 10 15 20 25 30X/D c

Figure 42: Axial distribution of maximum Specific Turbulence Kinetic Energy [kJ/kg]

30

REPORT DOCUMENTATION PAGE Form ApprovedOMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing datasources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any otheraspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations andReports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188),Washington, DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

September 2001 Contractor Report

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Computational Analyses of Propulsion Aeroacoustics for Mixed Flow

Nozzle Pylon Installation at Takeoff PO L-13395

6.AUTHOR(S)Steven J. Massey and Kenrick A. Waithe

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Eagle Aeronautics, IncHampton, VAAnalytical Services and Materials, Inc.

Hampton, VA

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space AdministrationLangley Research Center

Hampton, VA 23681-2199

WU 706-32-41-03

8. PERFORMING ORGANIZATION

REPORT NUMBER

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA/CR-2001-211056

11. SUPPLEMENTARY NOTES

Langley Technical Monitor: S. Paul Pao

12a. DISTRI BUTION/AVAILABILITY STATEMENT

Unclassified -Unlimited

Subject Category 02 Distribution: NonstandardAvailability: NASA CASI (301) 621-0390

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A CFD analyses is presented for a set of baseline and noise suppression mixed flow nozzles with and without a

pylon installation. The five model configurations are as follows; a baselinecore/fan dual-stream nozzle with anexternal plug, a chevron mixer nozzle with a peak on the symmetry plane with external plug, both of the above

nozzles with an installed bifurcatingpylon and lastly a clocked chevron mixer nozzle such that a trough isaligned with the center of the pylon. The fluid flow is simulated by solving the asymptotically steady,

compressible, Reynolds-averaged Navier-Stokes equations using an implicit, up-wind, flux-difference splittingfinite volume scheme and standard two equation k-epsilon turbulence model with a linear stress representation.

All computations are performed using the multiblock, parallel, structuredcode PAB3D. Results indicate that theclocked chevron with pylon case achieves the most optimal levels of average and peak turbulence kinetic

energy and vorticity and therefore is expected to be the quietest of the five configurations tested. Further study isrequired to refine expressions which are indicative of noise and mate these with rigorous noise predictionmodels.

14. SUBJECT TERMS

PAB3D; CFD; Aeroacoustics; Pylon; Chevron; PAA; QAT

17. SECURITY CLASSIFICATIONOF REPORT

Unclassified

18. SECURITY CLASSIFICATIONOF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATIONOF ABSTRACT

Unclassified

15. NUMBER OF PAGES

3516. PRICE CODE

A03

20. LIMITATIONOF ABSTRACT

UE

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