A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is provided. These data are to be used to evaluate, and verify, three-dimensional internal viscous flow models and computational codes. The analytical contract objective is to select a computational code and define the capabilities of this code to predict the experimental results obtained. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated. Internal flow in a large rectangular cross-sectioned 90 deg. bend turning duct was studied. The duct construction was designed to allow detailed measurements to be made for the following three duct wall conditions: (1) an isothermal wall with isothermal flow; (2) an adiabatic wall with convective heat transfer by mixing between an unheated surrounding flow; and (3) an isothermal wall with heat transfer from a uniformly hot inlet flow

Schulz, R. J.

English

NASA Technical Reports Server

GAS FLOW ENVIRONMENT AND HEAT TRANSFER 
NONROTATING 3D PROGRAM 
Roy J. Schulz 
The University of Tennessee Space Institute 
Tullahoma, Tennessee 
OBJECTIVES 
The experimental contract objective is to provide a complete set of "benchmark" 
quality data for the flow and heat transfer within a large rectangular turning duct. 
These data are to be used to evaluate, and verify, three-dimensional internal 
viscous flow models and computational codes. The analytical contract objective is 
to select such a computational code and define the capabilities of this code to pre-
dict the experimental results obtained experimentally. Details of the proper code 
operation will be defined and impro\'~Ulellts to the code modeling capabilities will be 
formulated. 
The experimental and analytical efforts are being conducted under a coor-
dinated multiphase contract. Phase one, the current ~rk, is the study of internal 
flow in a large rectangular cross-sectioned, 90° bend turning duct, and is planned as 
a 28 month study wilich started in April, 1982. Phase one is divid~!.t.1p.l;.9 __ five tasks, 
numbered I through V. Future ~rk to be performed at NASA's option includes the 
1nvestigation of flow over an airfoil cascade, with and without film cooling, inside 
the turning radius -of the duct. This future ~rk is designated as phases t~ and three 
of the contract. Phase t~, consisting of Tasks VI through XI, will consider a large 
scale cascade wnere "benchmark" data will be obtained to document the viscous flow 
field, pressure distribution and heat transfer phenomenon. Phase three of the 
contract, consisting of Tasks XII through XVI, in~ludes mass flow injection from 
cascaded airfoils to document the flow field and heat transfer with film cooling of 
the blades. 
APPROACH 
Separate experimental and analytical approaches have-been undertaken to attain 
the contract objectives. The experimental approach for Phase 1, the current ~rk, 
initiated with design, fabrication, and instrumentation of a large rectangular 
turning duct with a 90° bend. Air flow· will be drawn through the duct using an 
induced draft fan with variable blade pitch and variable rotation speed, to provide 
both a range of flow conditions in the duct and controllability for maintaining 
constant conditions during testing. The duct has been designed to be assembled in 
modules, allowing simple modifications of the duct for varying the inlet length or the 
wall boundary layer conditions.· The duct construction is designed to allow detailed 
measurements to be made for the following three duct wall conditions: 1) an isother-
mal wall with isothermal flow, 2) an a4iabatic wall with convective heat transfer by 
mixing between unheated surrounding flow, and 3) an isothermal wall with heat transfer 
from a uniformly hot inlet flow. Measurements for all three conditions will be made 
at two bulk Reynolds numbers and different inlet lengths to provide both laminar and 
fully turbulent boundary layer flows approaching the duct turn. The flow velocities 
for both Reynolds numbers will be low enough to remain well within the incompressible 
Mach number range so that only thermally induced density gradients will be encoun-
tered. 
149 
https://ntrs.nasa.gov/search.jsp?R=19850002658 2020-03-20T21:16:28+00:00Z
The primary inscrumentation being assembled for the flow measurements is a 
. three-dimensional, vector laser velocimeter (LV). The LV will use tlolO colors and 
Bragg diffraction beam splitting/frequency shifting to separate the three simulta-
neous, orthogonal, vector velocity components. The LV signal processors determine 
digital values of velocity for the ~eeded flows from particle crossing the laser beam 
generated probe volume. To simplify and speed up digital data acquisition, the LV pro-
cessors are built around an S-lOO bus Z-80 microprocessor, which provides the addi-
tional advantage of on-line, near-real time data reduction. This on-line data 
reduction capability will be used to assess the adequacy and precision of the data as 
it is acquired and recorded for more complex, off-line detailed analysis. To help 
qualify the measurements as "benchmark" data, the LV measurements will be compared 
with both pitot probe and hot wire anemometer measurements for flow conditions Which 
permi t these compar··.sons 
The analytical approach initiated with a search for candidate state-of-the-art 
numerical solution t,rocedures for internal, three-dimensional viscous flows. The tlolO 
candidate codes selected were the P. D. Thomas Beam-Warming code and the Briley-McDonald 
"MINT" code. With both codes and their available docqmentation obtained, a comparison 
of them will be made in terms of user orientation, documentation, numerics, physical 
modeling, accuracy, grid sensitivity, boundary conditions, formulation, CPU time and 
ease of extension to future problems. Initial results will Le obtained for calibra-
tion purposes and compared to published results, and with flows visualized and 
measured with a 2-D LV system in a 1/3 scale duct. Then numerical convergence proper-
ties and grid refinement techniques will be studied, both by uniform refinement and by 
local clustering of the mesh points. After the effects of discretization error h~ve 
been estimated the code predictions will be compared with full scale experimental data 
as it is obtained, for laminar flow and turbulent-flow to evaluate available tur-
bulence models. Finally, heat transfer modeling will be evaluated, and the best of 
the codes selected for a detailed comparison with the experimental data. This 
detailed comparison will determine the accuracy of the code's calculated flow field 
and generate recommendations and formulations for code improvement. 
CURRENT RESULTS AND PLANS 
Both the experimental and analytical phases are currently underway. The experi-
mental phase has involved test facility and instrumentation design and fabrication •. 
The turning duct design has been approved by NASA program monitors and is 
essentially an induced draft wind tunnel with a 90° bend test section. Nominal bulk 
flow velocities of 6.096 m/sec (20 ft/sec) and 60.96 m/sec (200 ft/sec) and dif-
ferent straight inlet lengths were selected for the low and high Reynolds number 
cases to provide moderately thick laminar and turbulent boundary layers entering the 
bend. The contour of the inlet transition,oor bellmouth, was designed by numerical 
calculations to provide smooth acceleration to the inlet section. The flow rates 
corresponding to the selected velocity were used ~o specify an induced draft fan for 
the duct exit, which in turn, established the diffuser configuration. The 90° curve 
section of the duct will be assembled from a series of flanged interchangeable modu-
les. Additionally, interchangeable instrument ac~ess modules provide access for 
probing the flow with the LV and with the pitot and hot wire probes. The duct will 
150 
be insulated for the adiabatic wall test cases, and water jackets will be added to 
establish the isothermal wall test cases. The LV window module allows optical 
access from all four walls of the duct, with an unobstructed field of view so that 
the LV probe volume can be traversed from wall to wall. The window segments are 
thin, optical flats Which are only 1.27 cm (42 in) wide along the inside wall. The 
windows were designed to minimize deviations from wall curvature on the convex and 
concave duct sidewalls. This test facility is presently in the materials acquisi-
tion and mechanical fabrication stage. 
The LV optical assembly will be mounted on a box beam structure Which fits 
around the duct. The LV scans the duct cross-plane and cross-stream coordinate 
directions by activating an LV microprocessor-controlled mill bed, to Which the box 
beam is mounted. The optical arrangement allows the three pairs of laser beams to 
cross coincident within + 0.5 mm, as well as forward scatter light collection for 
greatest signal to noise-ratio. The signal to noise ratio and processor accuracy are 
also improved by mixing the collected signals with accurately known oscillators that 
downbeat the signals to lower frequencies. The reduced signal frequencies eliminate 
the effects of small deviations centered on very high RF carrier frequencies from 
affecting the measurements. Hardware is being acquired and software is being deve-
loped for improved on-line graphics for data reduction and presentation Which allows 
assessment of the validity and precision of the LV measurements as they are being 
acquired. This significantly improves the established levels of statistical con-
fidence and also helps assure that all critical physical flow features are being 
measured. LV system development is moving into the shakedown stage, Which is being 
initiated by evaluating the flow in a 1/3 scale model duct. An evaluation of LV com-
patability with the windowed optical access module is also planned before LV and 
intrusive probe comparison testing is initiated~ 
The analytical effort is also well underway. One of the selected computational 
codes, the P. D. Thomas code, was received for evaluation, and requests have been made 
for a recent version of the Briley-McDonald "MINT" code. The P. D. Thomas code has 
extensive documentation and has been adapted to the experimental geometry of the 90° 
bend duct. Numerically converged results have been obtained for a published, laminar 
flow case. Also, the initial results were compared to published solutions of the 
"MINT" code for the same flow, Which includes duct geometry and Reynolds number, 
al though the flow inle t Mach number used for the Thomas code was grea ter • Wi th 
either computer code discrepancies between computed solutions and experimental 
measurements for both laminar and turbulent flows have been reported. The source of 
the discrepancy seems to be discretization error, and derive a set of approximate 
solution errors. Also, solutions of both codes will be compared with flow visualiza-
tion in a 1/3 scale duct, to help identify problem areas with both code results. 
151 
1-1 
CJ1 
N 
. il ,. 
TI h,:1 
t.=lL 
GAS FLOW ENVIRONMENT AND BEAT TRANSFER-
NONROTA11NG 3D PROGRAM 
NASA CONTRACT NAS3-23276 
Roy J. Schulz. PhD .. P.E. 
OBJECTIVES 
• PRovIDE -BENCHIIARK- lATA IEUNEATING 3-D VISCOUS I1.Dt WITH ~AT TRANSFER 
ON A lARGE, RECTANGlfLAR, q(l" !leND TURN I NG IUCT 
.fIlASE 
1. l1.ow IlEVELOI'HENT IN THE BEND WITH 01 FFEREtfT INLET BOUNDARY 
LAYERS AND WALL HEAT FLUX DISTRIBUTIONS <TASK I-V) 
2. l1.ow DEVELOPI1ENT IN THE BEND WITH AN IMBEDDED CASCADE BLADE 
SYSTEIt FOR DIFFERENT INLET BOUrlDARY LAYERS AND WALL HEAT 
FLUX DISTRIBUTION (TASKS VI-XI) 
3. I1.Dt DEVELOPMENT IN THE BEND WITH All IMBEDDED CASCADE BLADE 
SYSTEIt USING AIR INJECTED THROUGH THE BLAfiES TO SIMUlATE FILM 
COOLING FOR DIFFERENT INLET BOUNDARY LAYERS AND WALL HEAT FLUX 
DISTRIJlJTlONS <TASK XII - XVI) 
• SELECT, EVALUATE, I'bDIFY ANWOR IEVELOP A STATE-OF-THE-ART 3-n VISCOUS 
flow Cort'UTER CoDE BY CoNFRONTATION WITH ExPERIMENTAL lATA (SAME 3 PHASES) 
• VALIDATE COIlES' CAPABILITY/ADAPTABILITY 
• ADD, IF NECESSARY, ENERGY TRANSFER/CONSERVATION EQUATION 
• EVALUATE TURJlJLENT TRANSPORT MODELS FOR THIS CLASS OF R.t1oIS 
• DEFINE MESH ESTABLISHMENT AND RESOLUTION REQUIRED FOR 
ACCURATE COMPUTATION OF THIS CLASS OF FLDtS· 
...... 
U1 
W 
EXPERIt.ENTAl. APPROACH 
BuILD FACILITY AND INSTRlI1ENTATlON 
• ItDI FIABLE CuRVED JlJCT 
• VARIABLE AIR 11.~ 
• SEG/'ENTED CoNSTRUCTI ON 
• LASER VELOCIHETER INSTRUI£NTATION 
SIHULTANE(lJS 3 CIH'ONENT DETERMINATION 
• BRAGG SYSTEM (VELOC ITY VECTOR I£ASUREI£NTs) 
• I1ICROPROCSSOR BASED SYSTEM - aJTLINE STATISTICAl.. MTA DETERMINATION 
VALIDATED AGAINST PITOT AND HOT WIRE SYSTEM 
• DuCT ExPERIMENTS - TO FACILITATE ANALYTICAL COMPARISONS 
• I)jHEATED FL(1oI - 2 ENTRANCE alNDI TlONS 
• I1IXING OF HOT AND COlD STRENIS WITH ADIABATIC WALL 
• IbT FL(J1/ WITH ISOTHERMAL WALL 
• CASCADE ExPERII£NT - BLADES INSTALLED IN WCT BEND 
• SAME SERIES AS DUCT EXPERIHENTS 
• REPEAT SERIES WITH SIMULATED FILH COOlING 
ANALYTICAl. APPROACH 
• CI»1PARE APPLICABLE 3-D CoDES WITH ADEQUATE OOCUI'fNTATlON 
LAMINAR 11.~ CALCULATIONS WITHClIT HEAT TRANSFER 
• MAPT CODE TO PROBLEH - BOUNDARY AND INITIAl, CONDITIONS 
CoMPARE WITH FL(1oI VISUALIZATION RESULTS 
• CoHPARE WITH PUBLISHED RESULTS FOR SIMILAR COIlFIGURATIONS 
• f'IIELIHINARY COMPARISON WITH DATA (INCLUDING TURBll.ENT FLOW AND HEAT 
TRANSFER), AS IT IS OBTAINED 
• CoMPARE CODES FOR RESOLUTION WITH EQUIVALENT GRIDS, COMPUTATIONAL 
TIME, STORAGE, EASE OF IMPLEI'fNTATION AND EASE OF MODIFICATION 
• SELECT CODE FOR DETAILED COMPARISON WITH DATA 
• DETAILED COMPARISONS WITH DATA 
• FoRttJLATE IHPROVEHENTS 
• EVALUATE SENSITIVITY TO GRID SPACING AND TIME STEP SELECTION 
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ST AlUS SU/MARY 
N.1lJ1ID!.I.M. 
DuCT DESIGN ApPROVED - DETAILED DRAWINGS AND FABRICATION STAGES 
LV !PTICAL DEsIGN BREADBOARDED - PREPARING FOR SHAKEDOWN TESTS (1/3 SCALE DUCT) 
LV PRocEssoR f'bDIFICATlOIIS LNDERWAY 
500 I1lz Q. OCK 
At~l 'illQ\!. 
3D SIMUlTANEITY 
(OllPUTER CoNTROLLED PoSITIONING 
{)j LINE [\\TA ~APHICS 
(ODES SELECTED FOR EVAlUATION 
p. n. THCJ1AS 
"Hlln-
• p. D. THCJ1AS CoDE SET UP/OPERATIONAL FOR fLow IN 91" BEND DuCT 
- RESULTS AGREE WITH PUBLISHED LITERATURE 
Ibr YET ABLE TO ACQUIRE "MIIIT" 
FUTURE PLANS 
Phase 1 
EXPER I ~(NTAl 
CoMPlETE DucT FABRICATION, INSTAlLATION AND SHAKEDOWN 
INITIATE 2-D LV MEASUREMENTS ON 113 SCAlE DUCT TO DEVELOP ON-LINE 
DATA REDUCTION AND TRAVERS ING SYSTEI1 SOFTWARE 
• COIf'lETE 3-D LV DEVELOPMENT AND SHAKEDOWN, ASCERTAINING MEASURD1ENT 
UNCERTAINTIES AND C<H'ARABlE ACCURACY TO PROBES 
• INITIATE ISOTHERMAL FLOW TESTS 
AtW.YI1(AI... 
IlITAIN "I1INY AND It.PUT BOONDARY AND INITiAl CONDITIONS FOR IlICT 
WITH l.AtIlNAR FLOW TO CIH'ARE WITH PUBliSHED RESlllTS· 
• INITIATE p. D. THOMAS AND "HINT" CODE C<H'ARISON WITH l.AtIlNAR 
FLOW VISUAliZATION IN 113 SCAlE DUCT 
• EVALUATElI100IFY TURBtLEI«:E ItlDEL AND PREDICT TURBULENT FLOW 
WITH BOTH COIlES. 


Gas flow environment and heat transfer nonrotating 3D program

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