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RPR 161-04 

BOUNDARY LAYER SIMULATION IMPROVEMENT 

Progress Report 

for 

March 1 1987 through May 31, 1987 

on 

Contract NAS8-36551 

10 June 1987 

Prepared for 

National Aeronautics and Space Administration 

George C. Marshall Space Flight Center 

Marshall Space Flight Center, AL 35812 

.a 

Prepared by: 

Dr. Sarat C. Praharaj 

iLASA-Cir- 178645) ECCBCAhY L2PEB SIEULATICN N87-26304 

IEEBCVEMENT Pxocrcss Eeycrt, 1 Car. - 31 Eay 
REMTECH INCBACKGROUND 

The objective of the study is to advance the current Boundary 

Layer Integral Matrix Procedure - Version J (BLIMPJ) with regard to 

the previously-modeled calculation methcds accounting for surface 

roughness, relaminarization, condensed phase, and thick boundary 

layer effects. Current analytical limitations will be relaxed to 

permit more realistic wall and flow conditicjns and to use 

appropriate turbulence models with specific emphasis for the projected Orbit Transfer Vehicle (OTV) engine application. The updates will be incorporated into the BLIMPJ computer program, and 

the modified program will be made operational on the MSFC CRAY computer system. An additional objective of this effort is to conduct 

experimental feasibility studies to find out how to obtain quality 

test data with advanced instrumentation for concept verification 

purposes. 

STATUS OF TASKS 

During the reporting period, work concentrated on Tasks 1, 2, 

and 4. The status of work on all tasks is provided in Table &. -In 

addition to the tasks reported here, an abstract was submitted to 

ZANNAF for presentation at the upcoming Combustion meeting. 

WALL ROUGHNESS 

The variable surface roughness option has been added to BLIMPJ 

and the checkout of this option is continuing. The application of 

surface roughness over two separate regions of the OTV nozzle was 

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REMTECH INC- RPR 161-04 

reported in RPR 161-02. From the figures provide? in this report 

it was 6emonstrated that, in regions away from the throat, the surface rougfiness option produced a? increase in the heat flux distribution. Figures 1 and 2 show the heat flux distribution in the 

throat reqion where variable rouohness was introduced. From these 

figures it can be seen that the heat flux does not maintain the 

slope of the heat flux distribution as it does in the other regions 

of the nozzle. The cause of this observation is not yet understood 

but work will continue in this area until it is resolved. 

ROUGSNESS DATA FOR THE 60° - 15’ CONICAL NOZZLE 

The Two-Dimensional Kinetic (TDK) computer code was run on 

REMTECII’s MicroVAX I1 computer for the 60’ half-angle of conv=rgence nozzle as mentioned In RPR 161-03. Analysis of the pressure 

data generate2 on the VAX version of TDK showed two slope discontinuities on both sides of nozzle throat. In order to see if the 

accuracy of the nozzle data generated by TDK would be improved, the 

UNIVAC version of TDK was run and the resulting theoretical data 

transferred to the VAX for use with BLINPZ. Fiqure 3 shows a Comparison of the TDK pressure ratio data generate6 by these two computers. It was seen that the upstream discontinuity was removed, 

whereas the discontinuity at the downstream geometrical attachment 

point remained. The TDK (theoretical) results were then used as 

input for BLIMPJ. BLIMPJ was run for four experimental nozzle wall 

roughness values. These values are smooth wall, 120 rms (1 x 

lO”ft), 175 rms (1.4583 x 10’5ft), and 325 rms (2.70833 x 

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REMTECH INC- RPR 161-04 

10-5ft). Figures 4 through 7 show the comparisons of the BLIMPJ 

(theoretical) film coefficients and the experimentally measured 

film coefficients. The experimental data is documented in NASA 

Technical Note, NASA TN 3-5887. The method of roughening the nozzle in this experiment was throuah sand blasting. The range of 

roughness in the nozzle was meascre6 to be within 210 percent of 

the normal value. The smooth wall film coefficients in Figure 4 

show good agreement over the full length of the nozzle. The rough 

wall film coefficients show good agreement along the lenath of the 

nozzle except in the throat region. In this region, the theoretical values are as much as 28 percent higher than the experimental 

values. This difference can be partially attributed to the accuracy of the roughness measurements (210 percent) and the accuracy 

of the heat-flux measurements (within 10 percent!. 

RELW.1 NARI ZAT I ON 

The above NASA document also contains low c5amber pressure 

data (30 psi and 75 psi) for which the turbulent boundary layer 

flow has been claimed to relaminarize. It has also been mentioned 

that the wall roughness tends to reduce relaminarization. A quick 

study using BSIMPJ suggested that the measure2 film coefficient 

data lay in between fully turbulent and fully laminar calculations. 

The initial attempts to turn on the relaminarization flag did not 

yield good comparison with data. Some of the problems were due to 

the pressure discontinuities that have been allude2 to earlier. 

However, work will continue to validate the relamina:--ation opti~n 

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REMTECH INC. RPR 161-04 

currently coded in SLIMPJ. 

THR'JST DECREMENT CALCVLATIOS 

Work began on development of a methodology for linking '_he TDK 

an2 3L'Y.T2 computer codes in or2er to perform thrust loss calcalations and, later, optimizations. The first task was to mozify the 

TDK code so that the temporary 2irect access file which contains 

the nozzle flow data would be save2 for later use. The secon2 task 

was to write a computer program that could use this 2irect access 

file to calculate the necessary data required to perform the thrust 

loss calculations in BLIMPJ. To facilitate talking about this code 

we will call it the Near-Wall Profile (NWP) code. 

Figures 8 and 9 are samples of the data generated by NWP. NWP 

performs a series of operations. First it identifies and stores 

the data associated with the points on a streamline, and secondly 

it interpolates the data from the streamlines that correspond to a 

specified X. The interpolated data for which profiles can be 

determined include pressure, density and velocity. Figure 9 shows 

six profiles that were generated using NWP. These profiles are for 

constant values of X and include data from all stored streamlines. 

Modifications are currently being added to NWP include limiting 

profiles to the boundary layer region and calculating profiles 

along lines normal to the nozzle wall. 

In generating the profiles with NWP it was found that two important factors must be considered when creating the direct access 

data file with TDK. One factor to consider is that it is necessary 

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RPR 161-04 

to extend the input wall profile well beyond the nozzle exit plane 

in order to calculate data throug5out the exit plane boundary layer 

region. The other important point to remember is that TDK overwrites the data in the direct access data file if the numer of data 

points exceeds the default (50000) and/or namelist input value of 

IDYLAX. 

PLANNED ACTIVITIES 

1. Check-out of roughness modules will be completed. 

2. The iteration procedure coupling TDK and BLIMPJ will be 

completed. 

3. Work on relaminariaation will be continued. 

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REMTECH INC, 

Wall roughness 

o Treatment of up to three 

sections with smooth/rough 

wall surfaces 

o Ccncept check-out 

Relaminarization 

o Wall roughness effect and 

o Freestream turbulence impact 

o Turbulence model 

mcdification 

o Cc,ncept check-out 

strong regenerative cooling 

Condensed Phase 

o Treatment of up to three 

sections with different 

ccndensed phase loading 

o Turbulence model 

representation 

o Concept check-out 

'Rxust Decrement Calculation 

o Coupling of TDK results 

with new BLIMP concept 

o Thrust loss optimization 

o Concept check-out 

Experimental Feasibility Studies 

o Identification of thrust 

chamber testing to obtain 

adequate data in support 

of wall roughness, relaminarization, condensed phase, 

thick boundary layer 

Instrumentat ion 

o Screening of instruments 

for B.L. testing for 

accuracy , locat ion, 

complexity, manufacturer 

and cost 

FOFPKJLATED 

o In Progress 

0 Completed 6 

CODED COMPLETED 

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