The 2-D axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow conditions were investigated. The effect of the parameters on isothermal flowfield patterns, time mean velocities and turbulence quantities is determined and an improved simulation in the form of a computer prediction code equipped with a suitable turbulence model is established. This is a prerequisite to the prediction of more complex turbulent reacting flows

Lilley, D. G.

English

NASA Technical Reports Server

TURBULENT COMBUSTOR FLOWFIELD INVESTIGATION 
David G. Lilley 
School of Mechanical and Aerospace Engineering 
Oklahoma State University 
Stillwater, Oklahoma 74078 
Experimental and theoretical research is being undertaken on 2-D 
axisymmetric geometries under low speed, nonreacting, turbulent, swirling flow 
conditions. The flow enters the test section and proceeds into a larger 
chamber (the expansion ratio D/d = 2) via a sudden or gradual expansion (side- 
wall angle a = 90 and 45 degrees). Inlet swirl vanes are adjustable to a 
variety of vane angles with values of @ = 0, 38, 45, 60 and 70 degrees being 
emphasized. The objective is to determine the effect of these parameters on 
isothermal flowfield patterns, time-mean velocities and turbulence quantities, 
and to establish an improved simulation in the form of a computer prediction 
code equipped with a suitable turbulence model. This is a prerequisite to the 
prediction of more complex turbulent reacting flows, and successful outcomes 
of the work can be incorporated into more combustion- and hardware-oriented 
activities, including incorporating the modeling aspects into already existing 
comprehensive numerical solution procedures. 
New features of the present year's study are: the turbulence 
measurements are being performed on swirling as we1 1 as nonswir 1 ing ' flow; and 
all measurements and computations are also being performed on a confined jet 
flowfield with realistic downstream blockage. Recent activity in the research 
program falls into three categories: 
1. Time-mean f lowf ield characterization by f ive-hole pi tot probe 
measurements and by flow visualization. 
2. Turbulence measurements by a variety of single- and multi-wire hot- 
wire probe techniques. 
3. Flowf ield computations using the computer code developed during the 
previous year's research program. 
In the experimental approach, flow visualization is accomplished by sti 11  
and movie photography of helium-filled soap bubbles and smoke produced by an 
injector and a smoke wire.' Time-mean velocities have been measured with a 
five-hole pitot probe at low swirl strengths, and this has recently been 
extended to higher swirl strengths, including the effect of size and location 
of a downstrean blockage of area ratio 2 and 4. Turbulence measurements have 
recently been *completed on swirling (up to 4 = 45 degrees) as well as, 
nonswirling flows using a six-orientation single-wire hot-wire technique. 
Although all Reynolds stresses are deducible by this technique, a new cross- 
wire probe is currently being used for more accurate shear stress 
evaluation. A series of hot-wire measurements are also in progress, using a 
three-wire hot-wire probe with direct computer inteface and data reduction. 
These data will enable turbulent viscosity components to be deduced (from the 
turbulence stress vs. mean velocity spatial gradients) and will aid the 
turbulence modeling aspects of the study. 
https://ntrs.nasa.gov/search.jsp?R=19830020949 2020-03-22T00:50:37+00:00Z
In the computational approach, an advanced computer code has been 
developed to predict corresponding confined swirling flows to these studied 
e~perimentally.~ Tentative predictions were given earlier.' Predictions have 
now been made which include realistic inlet conditions for a complete range of 
swirl strengths. Predictions of downstream blockage (two blockage sizes at 
two axial locations) have also been completed and these are being assessed in 
the light of the experimental data. Advanced versions of the code will 
incorporate modification in the form of state-of-the-art turbulence models, 
deduced from the experiments and elsewhere, so as to accommodate better the 
physics of swirling recirculating flows. 
Proposed future studies include: expansion ratio D/d = 1.5, 
correspondingly predictions using advanced turbulence models, inlet turbulence 
level effects to be clarified, turbulence length scales to be measured, and 
turbulence model developments to be made.The completion of these tasks will 
make a substantial contribution to the understanding and predictive capability 
of complex turbulent swirling recirculating flows. 
References 
1. Rhode, D. L., Lilley, D. G., and McLaughlin, D. K., "On the 
Predictions of Swirling Flowfields Found in Axisymmetric Combustor 
Geometries", ASME Symposium on Fluid Mechanics of Combustion Systems, 
Boulder, COY June 22-24, 1981, pp. 257-266. Journal of Fluids Engng., 
1982 (in press). 
2. Rhode, D. L., Lilley, D. G., and McLaughlin, D. K., Mean Flowfields in 
Axi symmetric Combustor Geometries with Swirl, AIAA Paper No. 82-0177, 
Orlando, Florida, Jan. 11-14, 1982. AIAA Journal, 1983 (in press). 
3. Lilley, D. G., and Rhode, D. L., A Computer Code for Swirling 
Turbulent Axisymmetric Recirculation Flows in Practical Isothermal 
Combustor Geometries, NASA CR-3442, Feb. 1982. 
4. Janjua, S. I., McLaughlin, D. K., Jackson, T. W., and Lilley, D. G., 
Turbulence Measurements in a Confined Jet Using a Six-Orientation Hot- 
Wire Probe Technique. Paper AIAA 82-1262, Cleveland, OH, June 21-23, 
1982. 
5.. Yoon, H.K., and Lilley, D. G. Five-Hole Pitot Probe Time-Mean 
Velocity Measurements in Confined Swirling Flows. AIAA Paper, Reno, 
NV, Jan. 10-13, 1983. 
6. Abujelala, M. T., and Lilley, D. G. Swirler Performance and Confined 
Sflirling Flow Predictions. AIAA Paper, Reno, NV, Jan. 10-13, 1983. 
1 .  I n t r o d u c t i o n  
1 .1  The T e s t  F a c i l i t y  
1 . 2  Research O b j e c t i v e s  
1 .  To de termine  t h e  e f f e c t  o f :  
* s w i r l  vane a n g l e  4 
* s i  de-wall  a n g l e  a 
* downstream blockage a r e a  r a t i o  A R  
and l o c a t i o n  L I D  
on: 
-
* i so the rma l  f l o w f i e l d  p a t t e r n s  
* t ime-mean ve l  oci t i  es 
* t u r b u l e n c e  q u a n t i  t i  es  
2 .  To e s t a b l i s h  an improved s i m u l a t i o n  i n  
t h e  form o f :  
* computer p r e d i c t i o n  code 
* s u i t a b l e  turbulen .ce  model 
1 .3  R e s e a r c h  A p p r o a c h  
1.  T ime-mean f l o w f i e l d  c h a r a c t e r i z a t i o n  b y  f i v e -  
h o l e  p i t o t  p r o b e  m e a s u r e m e n t s  a n d  b y  f l o w  
v i s u a l i z a t i o n .  
2 .  T u r b u l e n c e  measu remen ts  b y  a  v a r i e t y  o f  s i n g l e -  
a n d  mu1 t i - w i  r e  h o t - w i  r e  p r o b e  t e c h n i q u e s .  
3 .  F l o w f i e l d  c o m p u t a t i o n s  u s i n g  t h e  c o m p u t e r  c o d e  
d e v e l o p e d  d u r i n g  t h e  p r e v i o u s  y e a r ' s  r e s e a r c h  
p r o g r a m .  
1 . 4  P r o g r e s s  D u r i n g  F i  r s t  Y e a r  ( 1 9 8 0 - 1 9 8 1 )  
1 .  T e s t  f a c i l i t y  - d e s i g n  a n d  c o n s t r u c t i o n ,  i n c l u d i n g  
v a r i a b l e  a n g l e  s w i  r l e r  a n d  e x p a n s i o n  b l o c k s .  
2 .  E x p e r i m e n t a l  t e c h n i q u e s  - f l o w  v i s u a l i z a t i o n ,  f i v e -  
h o l e  p i t o t  p r o b e  a n d  r e d u c t i o n  c o m p u t e r  code .  
3 .  C o m p u t a t i o n a l  c o d e  d e v e l o p m e n t  - a d v a n c e d  v e r s i o n  
o f  a  p r i m i t i v e - v a r i a b l e  s o l u t i o n  p r o c e d u r e  - 
STARPIC. 
4 .  F l o w f i e l d  c h a r a c t e r i z a t i o n  - e m p h a s i s  on  t i m e - m e a n  
f l o w  c h a r a c t e r ,  u s i n g  f l o w  v i s u a l i z a t i o n ,  f i v e -  
h o l e  p i  t o t  p r o b e  a n d  t e n t a t i v e  p r e d i c t i o n s .  
1 . 5  P r o g r e s s  D u r i n g  Second  Y e a r  ( 1 9 8 1  - 1 9 8 2 )  
1 .  H i g h e r  s w i r l  s t r e n g t h s  - f l o w  v i s u a l i z a t i o n  a n d  
f i v e - h o l e  p i  t o t  p r o b e  m e a s u r e m e n t s .  
2 .  S w i r l e r  e f f e c t i v e n e s s  - e x i t  p r o f i l e s  o f  u, v, w, 
a n d  p  a c c u r a t e l y  e s t a b l i s h e d .  
3 .  F l o w f i e l d  p r e d i c t i o n s  - t h e  n e e d  f o r  s p e c i f y i n g  t h e  
i n 1  e t  c o n d i t i o n s  v e r y  p r e c i s e l y .  
4. D o w n s t r e a m  b l o c k a g e  - e f f e c t s  o f  a r e a  r a t i o  a n d  
a x i a l  l o c a t i o n  s t u d i e d  b y  f l o w  v i s u a l i z a t i o n ,  f i v e -  
h o l e  p i t o t  p r o b e  a n d  c o r r e s p o n d i n g  c o m p u t e r  
p r e d i c t i o n s .  
5 .  T u r b u l e n c e  m e a s u r e m e n t s  - i n  n o n s w i r l i n g  a n d  s w i r l i n g  
f l o w  v i a  o n e - w i  r e ,  t w o - w i  r e  a n d  t h r e e - w i  r e  h o t - w i  r e  
m e t h o d s .  
1 . 6  P r e s e n t  S t u d i e s  ( 1 9 8 2  - 1 9 8 3 )  
1 .  E x p a n s i o n  r a t i o  D /d  = 1 . 5  
2 .  C o r r e s p o n d i  ng  p r e d i c t i o n s  
3 .  T u r b u l e n c e  m e a s u r e m e n t s  a t  h i g h e r  s w i r l  
s t r e n g t h s ,  'w i  t h  a n d  w i t h o u t  d o w n s t r e a m  b l o c k a g e .  
4 .  T u r b u l e n c e  1  e n g t h  s c a l e  b e i n g  m e a s u r e d  
5.  T u r b u l e n c e  m o d e l  d e v e l o p m e n t s  
2 .  Swirl  e r  Performance 
2.1 Swirl  E f f e c t  on Axial a n d -  Swir l  V e l o c i t i e s  
00 
e 
Z 
w 
t- 
- 
r n  
w 
a- 
2 
a 
- 
0 
a 
e 
( a )  4 = 0" (No Swirl e r )  
( b )  @ = 45" 
( I0  
-5 
0 ' 
q o ~ . O O  O.SD 1 . O C  1 . 5 0  ;.OD 
e S U J R L  V r L O C J 7 Y  U/UBRR 
:'?DO <.SO ,:DL' I:SC ;.DO 
e S U J R L  V t L O C 1 7 Y  U l U B R R  
( c )  @ = 70" 
3. Time-Mean Vel oci  t y  Measurements 
3.1 Swirl  E f f e c t  on Axial and Swir l  Ve loc i ty  F i e l d s  
( a )  U /U ,  (a) + = 0° 
( b )  w/uo ( b )  9 = 45" 
l a )  U / U ,  
3 . 2  C o n t r a c t i o n  Block ( A R  = 2 )  E f f e c t  on $I = 4 5  
Degree Fl owf i e l  d 
( a )  L I D  = 1 .0  
( b )  L I D  = 2.0  
3 . 3  C o n t r a c t i o n  B l o c k  ( A R  = 4 )  E f f e c t  o n  $I = 4 5  
D e g r e e  F l o w f i e l d  
( a )  L ID = 1.0 
( b )  LID = 2.0 
3 .4  S w i r l  E f f e c t  o n  S t r e , a m l j n e s :  No D o w n s t r e a m  
B l o c k a g e  
( a )  Q = O 0  
0.5 pn Vortex Core 
0.5 
Vortex Core 
/ wp ------------- -- 
(c) 4 = 70" 
3 .5  S w i r l  E f f e c t  .on S t r e a m 1  i n e s  : Weak D o w n s t r e a m  
B l o c k a g e  a t  L / D  = 2 .0  
- 
( a )  9 = 0 "  
0.5 Vortex Core 
- - - - - - _ _  
OF=- ____-- - -  ---- - 
- 0 . 5 h  I I 
3.6  Swi r l  E f f e c t  on S t r e a m l i n e s :  S t r o n g  C o n t r a c t i o n  
Blockage  a t  L / D  = 2 . 0  
( a )  4 = 0 "  
( b )  @ = 4 5 "  
4 .  Computa t iona l  S t u d i e s  
4.1 P r e d i c t e d  Axia l  and Swi r l  V e l o c i t y  F i e l d s  f o r  
$ = 45 Degree ;F lowf i  e l  d 
Measured i n l e t  u ,  v and w p r o f i l e s .  
S t a n d a r d  k - E  t u r b u l e n c e  model .  
4 .2  S w i r l  E f f e c t  on Stream1 i n e s :  No Downstream Blockage  
- 
.50, - 
1 I I 1 
0 . 0 0  
I I 
0 . 5 0  1 . 0 0  1 .SO 2 .00  2 . 5 0  3 .  
( a )  @ = O 0  X / D  
I I I I I 1 
0 . 0 0  0 . 5 0  1  . O O  1  .SO 2 .00  2 . 5 0  3. 
( b )  @ = 45O X / D  
4 . 3  S w i r l  E f f e c t  on S t r e a m l i n e s :  S t r o n g  C o n t r a c t i o n  
Blockage  a t  L J D  = 2.0 
- 
-0.50. I I I I 
' .  00 0 .50  1 . 0 0  1 .SO 2 .00  2 .50  3 . 0 0  
X / D  
( b )  cp = 4 5 "  
-0.25 - 
-0,SO. I I 
( c )  @ = 70" X / D  
5 .  Hot-Wi r e  Anemometry 
5 . 1  Turbulence Measurements: Nonswirl ing Flow 
- Present Study - - - - Chaturvedl 
5 . 2  T u r b u l e n c e  M e a s u r e m e n t s :  S w i r l i n g  F l o w  @ = 38 D e g r e e s  
6 .  C l o s u r e  
1 .  Measu remen ts  o f  e f f e c t  o f  s w i r l ,  e x p a n s i o n  a n g l e  
a n d  c o n t r a c t i o n  b l o c k a g e  - o n  f l o w f i e l d  p a t t e r n s ,  
t i m e - m e a n  v e l o c i t i e s  a n d  t u r b u l e n c e  q u a n t i t i e s .  
2 .  C o m p u t e r  p r e d i  c t i o n  s t u d i  es o f  a s s o c i  a t e d  phenomena.  
3 .  T u r b u l e n c e  m o d e l  d e v e l o p m e n t s  f o r  t h e  s i m u l a t i o n  
o f  s w i r l i n g  r e c i r c u l a t i n g  f l o w .  
z a a 
$ 4 0  m 
- 0  
.D 0 
0.. 
. o  
- 
z 
L .  
e 
. . 
- 
l o .  
m 
0. 
0  
8 s .  
2 . 6 -  LI. Lo' &I. &I* LI. % Len La6 &,a La. Lr % 
- 4  
- L r  tr L L I. L a  
~ ' r * / u ~  10-I r*w*lu,, 16' 
* 
L .  0 
i . . e  * 
. D 0 
. . 0 
.. I) 
A *  m 6 0  
. .a 
m S 
I 0  
6 .  . D  e 
.0 0 
..D 
.. 0  
o *  6 
L 0 
0 
a 
Y 
* 
a 
* 
e 
z 
i 
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A .  D S 
. a 
.. 0 
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- 
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Turbulent Combustor Flowfield Investigation

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