A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is being compiled. These data will be used to evaluate and verify three dimensional internal viscous flow models and computational codes. The analytical objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated

Geil, T.

Steinhoff, J.

English

NASA Technical Reports Server

GAS FLOW ENVIRONMENTAL AND HEAT TRANSFER 
NONROTATING 3D PROGRAM 
T, G e i l  and J.  Ste inho f f  
U n i v e r s i t y  o f  Tennessee Space I n s t i t u t e  
OBJECTIVES 
The experimental c o n t r a c t  o b j e c t i v e  i s  t o  provide a complete s e t  of "benchmark" 
q u a l i t y  d a t a  f o r  t h e  f low and hea t  t r a n s f e r  w i th in  a " large" r ec t angu la r  t u rn ing  
duc t .  These d a t a  a r e  t o  be used t o  eva lua t e  and v e r i f y  three-dimensional i n t e r n a l  
v i scous  flow models and computational codes. The a n a l y t i c a l  con t r ac t  o b j e c t i v e  is t o  
s e l e c t  such a computational code and d e f i n e  t h e  c a p a b i l i t i e s  of t h i s  code t o  p r e d i c t  
t h e  experimental  r e s u l t s .  D e t a i l s  of t h e  proper  code ope ra t ion  w i l l  be  def ined and 
improvements t o  t h e  code modeling c a p a b i l i t i e s  w i l l  be formulated. 
The experimental and a n a l y t i c a l  e f f o r t s  a r e  being conducted under a coordinated 
mult iphase con t r ac t .  Phase one, t h e  cu r r en t  work, i s  t h e  s tudy  of i n t e r n a l  f low i n  
a r ec t angu la r ,  square cross-sect ioned,  900 bend tu rn ing  duc t ,  and i s  planned as a 28 
month i n v e s t i g a t i o n  which s t a r t e d  i n  Apr i l ,  1982. Phase one is  d iv ided  i n t o  t h e  
fo l lowing  f i v e  t a s k s :  I. Design and Fabr i ca t ion ,  11. Experimental Veloc i ty  Mea- 
surements,  111. Experimental Heat T rans fe r ,  I V .  Theore t i ca l  Analysis  and Data 
Comparison, V. Reporting and Technical  D a t a .  Fu ture  work t o  be performed a t  NASA's 
opt ion  inc ludes  t h e  i n v e s t i g a t i o n  of flow over  an a i r f o i l  cascade, w i t h  and without  
f i l m  cool ing ,  i n s i d e  t h e  tu rn ing  r a d i u s  of t h e  duct .  
Separa te  bu t  coordinated experimental and a n a l y t i c  approaches a r e  i n  progress  
t o  a t t a i n  t h e  con t r ac t  o b j e c t i v e s .  
APPROACH, EXPERIMENTAL 
The experimental  f a c i l i t y  design f e a t u r e s  modular t unne l  components which al low 
flow measurements every 150 i n  t h e  90° bend. The 25.4 cm (10 i n )  square c r o s s  sec- 
t i o n  tunnel  i s  designed wi th  a 13 t o  1 a r e a  r a t i o  b e l l  mouth contoured t o  provide  
uniform flow v e l o c i t y  and is  powered by a v a r i a b l e  speed, six-bladed f an .  (See 
F igures  1 and 2 ) .  The tunne l  is  designed f o r  incompressible  flow and w i l l  produce 
Reynolds numbers of 0.2 t o  2.0 X lo6  a t  t h e  en t rance  of t h e  90° bend f o r  t unne l  velo-  
c i t i e s  of 6 t o  30 mlsec (20 t o  100 f t l s e c ) .  These two flow condi t ions  provide  
laminar and f u l l y  t u rbu len t  boundary l a y e r  p r o f i l e s  a t  t h e  en t rance  t o  t h e  90' bend. 
The f a c i l i t y  is  a l s o  designed f o r  a d i a b a t i c  w a l l  t e s t i n g  wi th  l a r g e  thermal  g r a d i e n t s  
i n  t h e  a i r  stream. Heated a i r  w i l l  be  provided by e l e c t r i c  r e s i s t a n c e  h e a t e r s  s i z e d  
so  t h a t  100 KW w i l l  produce a minimum of 1 1 0 ~ ~  (200'~) temperature i nc rease  i n  t h e  
a i r  stream. 
The primary ins t rumenta t ion  is  designed f o r  non- in t rus ive  flow measurements 
u t i l i z i n g  a three-dimensional,  l a s e r  ve loc imeter  (LV) and wa l l  s t a t i c  p re s su re  and 
hea t  f l u x  gages. The LV u t i l i z e s  two co lo r  beams and Bragg d i f f r a c t i o n  beam s p l i t -  
t ing / f requency  s h i f t i n g  t o  s e p a r a t e  t h e  t h r e e  simultaneous, or thogonal ,  v e c t o r  
v e l o c i t y  components. The LV s i g n a l  processors  determine t h e  d i g i t a l  va lues  of velo-  
c i t y  from t h e  seed p a r t i c l e s  c ros s ing  t h e  l a s e r  beam probe volume. To improve and 
speed up d i g i t a l  d a t a  a c q u i s i t i o n ,  t h e  LV processors  a r e  designed around an S-100 
Work done under NASA c o n t r a c t  NSA3-23278. 
https://ntrs.nasa.gov/search.jsp?R=19860002039 2020-03-20T16:12:49+00:00Z
bus 2-80 microprocessor  which provides  on- l ine ,  near - rea l  t ime d a t a  reduct ion .  This  
on- l ine  d a t a  r educ t ion  c a p a b i l i t y  w i l l  be used t o  a s s e s s  t h e  adequacy and p r e c i s i o n  
of t h e  d a t a  a s  i t  is  acqui red  and recorded f o r  o f f - l i n e  d e t a i l e d  a n a l y s i s .  Typica l  
d a t a  output  i s  shown i n  F igure  3. To q u a l i f y  t h e  measurements a s  "benchmark" d a t a ,  
t h e  LV d a t a  w i l l  be  compared wi th  both p i t o t  probe and hot  wi re  anemometer measure- 
ments f o r  f low cond i t i ons  which permit  comparisons. 
CURRENT RESULTS AND PLANS, EXPERIMENTAL 
A l l  experimental  hardware and ins t rumenta t ion  systems have been designed,  f a b r i -  
c a t e d ,  assembled, i n s t a l l e d  and checked ou t .  Only t h e  a i r  h e a t e r  remains t o  be 
f a b r i c a t e d ,  and only  t h e  h e a t  f l u x  measurement system remains t o  be checked . Exten- 
s i v e  tunne l  f low q u a l i t y  surveys have been completed i n  t h e  i n l e t  s e c t i o n  fo l lowing  
"benchmark" c a l i b r a t i o n  of t h e  LV system, p i t o t - s t a t i c ,  and ho t  wi re  anemometer. A l l  
t h r e e  measurement systems were c a l i b r a t e d  a g a i n s t  r e f e rence  s t anda rds  and were found 
t o  ag ree  w i t h i n  f 1% on t h e  en t r ance  s e c t i o n  v e l o c i t y .  The LV system was c a l i b r a t e d  
wi th  a  sp inning  d i s k  r e f e rence  v e l o c i t y  a t  20 m/sec. The p i t o t - s t a t i c  p re s su re s  were 
read on a  p r e c i s i o n  s l a n t  manometer w i t h  13mm of Hz0 f u l l  s c a l e .  The hot-wire system 
w a s  c a l i b r a t e d  i n  a r e f e r e n c e  nozz le  f low at 30.5 m f s e c .  Veloc i ty  surveys taken 50.8 
cm (20 i n )  behind t h e  b e l l  mouth e x i t  showed f l a t  v e l o c i t y  p r o f i l e s  f 0.5% mean ve lo-  
c i t y  o u t s i d e  of t h e  boundary l a y e r .  Laminar and t u r b u l e n t  boundary l a y e r s  were 
measured a t  v e l o c i t i e s  of 4 .5  m/sec and 19.4 m/sec, r e s p e c t i v e l y  as shown i n  F igure  
4. Most s i g n i f i c a n t  f i n d i n g  w a s  t h a t  t h e  LV and hot-wire turbulence  i n t e n s i t y  mea- 
surements agreed wi th in  10% o r  nominally 1% turbulence  i n t e n s i t y .  The m i l l  bed 
t r a v e r s e  system has  demonstrated repea ted  accuracy of O . l m m  on a l l  t h r e e  a x i s  of 
movement. Both LV and probe p o s i t i o n s  a r e  c o n t r o l l e d  by t h e  computer dr iven  m i l l  
bed. 
Development of t h e  f low seeding system w a s  s u c c e s s f u l l y  completed dur ing  t h e  LV 
system checkout. Phenolic  micro-ballons of 2-5 micron s i z e  a r e  sprayed i n  a  s l u r r y  
of a l coho l  and water  i n t o  t h e  a i r  s t ream i n  f r o n t  of t h e  b e l l  mouth. Uniform seed 
d i s t r i b u t i o n  was obta ined  i n  t h e  t e s t  s e c t i o n  wi th  t h i s  system. 
The experimental  e f f o r t  is progress ing  toward completion of f low measurements 
a t  t h e  seven s t a t i o n s  i n  t h e  90' duct  f o r  t h e  unheated flow. A minimum of 300 
s p a t i a l  p o i n t s  i n  t h e  duct ha l f -p lane  a r e  being surveyed f o r  mean v e l o c i t y ,  unsteady 
v e l o c i t y  and t o t a l  p re s su re  a t  each s t a t i o n .  A f t e r  completion of t h e  unheated f low 
surveys at two Reynolds numbers, scheduled f o r  1 December 1983, t h e  a i r  h e a t e r  and 
tunne l  i n s u l a t i o n  w i l l  be i n s t a l l e d  f o r  t h e  a d i a b a t i c  wa l l  t e s t i n g  during t h e  win te r  
months when lower ambient temperatures  w i l l  reduce tunne l  w a l l  temperatures .  The 
experimental  phase of t h i s  e f f o r t  is  scheduled f o r  completion i n  May, 1983. 
APPROACH, ANALYTICAL 
The a n a l y t i c a l  approach involves ,  f i r s t ,  s e l e c t i n g  a  computer code capable of 
so lv ing  t h e  Navier S tokes  equat ions  wi th  turbulence  models f o r  t h r e e  dimensional 
i n t e r n a l  f low,  and adapt ing  i t  t o  t h e  experimental  geometry and flow condi t ions .  
Af t e r  t h i s ,  c a l c u l a t i o n s  a r e  t o  be  made f o r  laminar  f low cond i t i ons  f o r  unheated 
flow. Analysis  of t h e s e  c a l c u l a t i o n s  w i l l  d e f i n e  t h e  g r i d  s i z e  and s t r e t c h i n g  fac-  
t o r s  r equ i r ed  f o r  adequate r e s o l u t i o n  a s  we l l  a s  t h e  va lues  of t i m e  s t e p s  and 
smoothing f a c t o r s  r equ i r ed  f o r  convergence. Also, any output  and g raph ic s  c a p a b i l i t y  
requi red  f o r  comparison wi th  d a t a  i s  t o  be developed during t h i s  phase. The 
adequacy of t h e  code wi th  r e spec t  t o  t h e  d i f f e r e n c i n g  scheme, a d a p t a b i l i t y  and con- 
vergence w i l l  be decided i n  t h i s  phase, by comparisons wi th  publ ished experimental  
and computational d a t a  and by g r i d  s e n s i t i v i t y  s t u d i e s .  
The next  phase of t h e  e f f o r t  involves  computation of hea ted  laminar  f lows  wi th  
a d i a b a t i c  wa l l  condi t ions .  This  c a l c u l a t i o n  i s  important  f o r  determining maximum 
w a l l  temperatures  t o  be expected i n  t h e  experiment.  It w i l l  a l s o  be important i n  
determining whether f o r  t h e  temperatures  planned,  t h e  v e l o c i t i e s  w i l l  d e v i a t e  s u f f i -  
c i e n t l y  from t h e  unheated case  t o  provide an i n t e r e s t i n g  flow. 
The t h i r d  phase involves  d e t a i l e d  comparison wi th  experiment f o r  laminar  f lows 
wi th  and without  hea t  added. The r e s o l u t i o n  of t h e  computer code w i l l  be t h e  main 
aspec t  t e s t e d  here .  The heated case  w i l l  involve  a d i a b a t i c  w a l l  condi t ions .  
The f o u r t h  phase involves  computing t u r b u l e n t  f lows corresponding t o  a c t u a l  
experimental  cond i t i ons ,  w i th  and without  hea t  added. P a r t i c u l a r  a t t e n t i o n  w i l l  be 
pa id  t o  t h e  t rea tment  of hea t  t r a n s p o r t  i n  t h e  turbulence  model. De ta i l ed  compari- 
sons wi th  experiment w i l l  be made. 
A f i n a l  phase involves  s e l e c t i v e  g r i d  ref inement  i n  r eg ions  where h igh  reso lu-  
t i o n  i s  r equ i r ed  so t h a t  a measure of t h e  numerical t r u n c a t i o n  e r r o r  can be obta ined .  
CURRENT RESULTS AND PLANS, ANALYTICAL 
The code s e l e c t e d  f o r  t h e  a n a l y t i c a l  s tudy  is a ve r s ion  of t h e  Beam-Warming 
a lgor i thm adapted t o  gene ra l i zed  coord ina t e  systems by P. D. Thomas. It i s  ve ry  we l l  
documented and r e l a t i v e l y  easy  t o  u se .  The o r i g i n a l  p lan  t o  u s e  t h e  "MINT" code 
developed by B r i l e y  and McDonald has  no t  been followed due t o  ou r  i n a b i l i t y  t o  o b t a i n  
t h e  code. De ta i l ed  comparisons of t h e  r e s u l t s  of our  code, f o r  a laminar  f low case ,  
w i th  publ ished r e s u l t s  of t h e  MINT code have been made. For comparable g r i d s  t h e  
codes gave similar r e s u l t s .  These r e s u l t s  have a l s o  been compared t o  publ ished 
experimental  r e s u l t s  as shown i n  F igure  5. This  comparison ind ica t ed  a discrepency 
which appeared t o  be due t o  l a c k  of adequate  r e s o l u t i o n  i n  t h e  computed r e s u l t s  f o r  
both codes. This  discrepency has been i n v e s t i g a t e d  by g r i d  refinement s t u d i e s .  
Fu r the r ,  t h e  e f f e c t  of t h e  g r i d  s t r e t c h i n g  f a c t o r s  on t h e  s o l u t i o n  has  been de t e r -  
mined. The t ime s t e p  s i z e  and smoothing f a c t o r s  have been determined which 
approximately opt imize  convergence f o r  t h i s  case.  A g raph ica l  d i s p l a y  program has 
been w r i t t e n  and used t o  s imu la t e  s t r eaml ines  i n  t h e  f low as shown i n  F igure  6. 
These r e s u l t s  have been q u a l i t a t i v e l y  compared w i t h  pre l iminary  experimental  r e s u l t s  
i n  a 1/3 s c a l e  duc t .  
A heated  laminar  f low c a s e  wi th  a d i a b a t i c  w a l l  cond i t i ons  w a s  then  computed. It 
was determined t h a t  t h e  w a l l  temperature a t  a po in t  n e a r  t h e  end of t h e  bend would be 
c l o s e  t o  t h e  maximum i n l e t  temperature,  which occurs  a t  t h e  c e n t e r  of t h e  duc t .  
Computed t o t a l  temperature p r o f i l e s  a r e  shown i n  F igure  7.  This  r e s u l t  i s  important 
i n  determining t h e  maximum a l lowable  i n l e t  temperature.  For t h e  temperature p r o f i l e  
considered,  which was c l o s e  t o  t h a t  planned in t h e  experiment,  i t  was a l s o  determined 
t h a t  t h e  v e l o c i t y  p r o f i l e s  would d i f f e r  s i g n i f i c a n t l y  from those  of t h e  unheated 
flow. Thus, t h e  heated f low experlment would r e s u l t  i n  a q u a l i t a t i v e l y  d i f f e r e n t  ' 
f low,  f o r  t h e  planned i n l e t  temperatures ,  and t h e  experiment would g i v e  u s e f u l  
r e s u l t s .  
Curren t ly ,  w e  a r e  running unheated t u r b u l e n t  f low cases .  Pre l iminary  r e s u l t s  
a r e  being s t u d i e d  t o  determine t h e  s e n s i t i v i t y  of t h e  r e s u l t s  t o  t h e  turbulence  
model parameters .  De ta i l ed  comparisons w i t h  experiment w i l l  be  made f o r  t h e  laminar  
ca ses ,  wi th  and without  hea t ing ,  as soon as they  a r e  a v a i l a b l e .  We w i l l  then  
proceed wi th  t h e  comparisons f o r  t u r b u l e n t  f low and a d d i t i o n a l  g r i d  ref inement  
s t u d i e s .  
Experimental Fac i l i t y  
Figure 1. 
LV and Pressure Instrumentation Deta i l  
Figure 2 .  
8 2 
Typica l  On-Line Data Disp lay  
X Y Z 
A s  i a1 C r o s s w i s e  Spanwi se 
( A c t i v e )  ( A t t i  u e )  ( f i c t i i l e )  
Long F r i n g e  Count  8 8 8 
S h o r t  F r i n g e  Count  5 J 5 C 
P r e c o u n  t 2 3 3 -, 
Clock  F r e q u e n c y  100.00 100. O(3 100.0C) 
High P a s s  F i l t a r  1.2207E-(j2 2.01~0i)E-0 : 1.00ijOE--0 1 
F r i n g e  P e r  i ud 46. 1.00 36. 030 15.360 
Maxi mum Aper i od i c i t.y 4. 000(:)Ei-00 4.0000~.+.0(3 4. 0000E +00 
B i a s  F r e q u e n c y  -. 60 . .30 -23  
P l a t f o r m  p o s i t i o n  .- (3 la(:) - . 0 1 00 -. 0100 
Timer R a t e  1 .  (3E-I.03 
Sample  S i z e  400 
Run Number 6 
X Y 
V r n i s  = 19.71 V = 17.69 - - - .,'.>I5 
SIGMkrms = -3668 SIGMA = -3660 - .230(3 
% =  1.862 % =  1.059 % = S1.44 
A c c e p t e d  = 271 = 348 = 326 
A p c r i o d i c i t y  f a i l u t - e s  = 52 = 74 -  
High p a s s  f i l t e r -  f a i l u r e s  = O = (1 - 
F r e q u e n c y  = . 1727 = .2797 - 
C o r r e l  a t  i on  Coef i i c i e n  t. = 5.42758E-02 
C o v a r i a n c e  = 2.82059E-04 
A c t i v e  
modes 
X Y Z  
PRINT 
PLOT 
HDCOPY 
Figure  3 .  
Entrance Region Boundary Layer P r o f i l e s  
A Laminar 
A - HW V = 1.5 ftlsec 
0 - LV 7 = 19.4 m/sec 
Turbulent 
U -  HW V = 65 ftlsec 
mm From Center of Wall 
Figure 4 
Axial Veloc3ty Comparison Analytic/Experimental 
--- Briley-McDonald "MINT" code 
125 
- P. D. Thomas code 
Convex 
Wall CR-R i )  / <Ro-R I) 
Cross-Channel Coordinates 
Ffgure 5. 
Concave 
Wall 
Total Temperature Profi le  a t  Bend Exit 
Laminar Flow, Adiabatic Wall 
TEMPERATURE FOR PH=SliS,@liS TIME STEP=l732 
convex (R-Ri )  / < R a - R i )  concave 
wall wall Cross-channel Coordinate 
Figure 7.  


Gas flow environmental and heat transfer nonrotating 3D program

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server