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TURBULENCE MODELING NEEDS OF COMMERCIAL CFD CODES: COMPLEX FLOWS
IN THE AEROSPACE AND AUTOMOTIVE INDUSTRIES
Bizhan A. Befrui
adapcoMelville, New York
N95- 27896
CONTENT OF PRESENTATION
• STAR-CD: COMPUTATIONAL FEATURES
• STAR-CD: TURBULENCE MODELS
• COMMON FEATURES OF INDUSTRIALCOMPLEX FLOWS
• INDUSTRY-SPECIFIC CFD DEVELOPMENTREQUIREMENTS
• INDUSTRIAL COMPLEX FLOWS:APPLICATIONS & EXPERIENCES
- FLOW IN ROTATING DISC CAVITIES
DIFFUSION HOLE FILM COOLING
- INTERNAL BLADE COOLING
EXTERNAL CAR AERODYNAMICS
• CONCLUSION: TURBULENCE MODELINGNEEDS
I STAR-CD: COMPUTATIONAL FEATURES 1
BODY-FITTED NON-ORTHOGONALCOORDINATE SYSTEM
• UNSTRUCTURED COMPUTATIONAL MESH,DIFFERENT CELL TOPOLOGIES, IMBEDDEDMESH REFINEMENT, DISCONTINUOUSMESH INTERFACE, MOVING BOUNDARYAND INTERNAL INTERFACES
• PRIMITIVE VARIABLE, SELF-ADAPTIVEELLIPTIC-HYPERBOLIC PRESSURECORRECTION METHOD
• COLLOCATED-VARIABLE ARRANGEMENT
• EULER-IMPLICIT TEMPORAL INTEGRATION
• UD, CD, LUD, SFCD SPATIALDISCRETIZATION, WITH BLENDINGCAPABILITY
171
https://ntrs.nasa.gov/search.jsp?R=19950021475 2018-04-18T01:06:59+00:00Z
l STAR-CD: TURBULENCE MODELS I
° TWO-EQUATION MODEL
- STANDARD k-e WITH CORRECTIONS FORBULK DILATATION AND BUOYANCY
- HIGH REYNOLDS NO. RNG BASED k-¢MODEL
• TWO-ZONE (TWO-LAYER} MODEL
- HIGH REYNOLDS NO.: k-s VARIANTS
- LOW REYNOLDS NO.: k-t VARIANTS,PRANDTL MIXINGLENGTH MODEL
STAR-CD: TURBULENCE MODELS I
• REYNOLDS STRESS TRANSPORT MODEL"
- TRANSPORT EQUATIONS FORCARTESIAN STRESS TENSOR IN NON-ORTHOGONAL COORDINATE SYSTEM,ON NON-STRUCTURED MESH
- LAUNDER, RODI, REECE (1975|FORMULATION WITH LAUNDER (1989]MODEL CONSTANTS
- GIBSON & LAUNDER (1978} WALLREFLECTION MODEL
172
Sep94VIEW
.0oo
.0D01.000
ANGLE.000
DISTANCE.340
CENTER.076.06*7
.003EHIODEN PLOT
Oev,,, & Seege=W eadera_ Fac_g StapRow Oema_. -20"H Io _'H
Ues_. ;05 (Aml) x 4S (Radial)
L
-J • J ,4 • • 1i I.,1 1.,4 1i 1,4 ._Z *.1 J .1 J • A • • .T •
100uuAJfld'2 -100uvAJrM'2
tL'J
. f _,,..-'"
GRAPH PLOTFRAMES
• F..m. dam
RS modJ
KE mod_
Dav_ & SeeOmeJef8emmrd F_O StepData Inlet B.C.
LocaM_l X/H - 1.5
173
sJ
Jii
u" -__ !
• i• i
_J
th
u
: I
u
u
H
u
j j ,4 • • tJ 1Jr t,s 1.4 lal J.J _t J .! J • .4 • • 3
u
_k u" k ,
t H " •
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7seps4
PLOT
FRAMES
Le_na
_ RS moClel
KE model
Driver & See(jmner Back'war¢l Facing Step
Data InM! B.C.; No waa Darap_ng Fur, or.
Lo(:a_oct X/H : 1.5
174
Z
175
2s,po4PRESSURE
N/M"2
L.O_M. MX= 329.9
L.OCAL MNs ,-29.3"/
4t0.0
3e0.7
351.3
322.O
25_7
2e_5
234.O
204.7
173..5
144..0
116.7
87"_
SS.00
28.67
-.e887
-30.00
0.5 LUO OIFFERENCINGTURBULENCE MOOEL _ - UPPER, RSM • LOWER
COMMON FEATURES OF INDUSTRIALCOMPLEX FLOWS
• THREE DIMENSIONAL WITH MULTIPLE FLOW"COMPLEXITIES"
BODY-FORCE FIELDS
- STREAM SURFACE CURVATURE
- STRONG PRESSURE GRADIENTS
- COMPRESSIBILITY EFFECTS
- LAMINAR-TURBULENT TRANSmON
- COMBUSTION, SHOCK, MULTIPHASE, NON-NEW'rONIAN
.
* LARGE SCALE DOMAIN AND COMPLEXGEOMETRIC CONRGURATION
• IRREGULAR, UNSTRUCTUREDCOMPUTATIONAL MESH
- SPATIAL RESOLUTION DIFFICULT TO ACHIEVEON O(10 s - 10 8) MESH CELLS
• INSUFFICIENT AND UNCERTAINEXPERIMENTAL DATA FOR TURBULENCE
MODEL VAUDATION/IDENTIFICATION OFDEFICIENCIES
176
INDUSTRY-SPECIFiC CFD DEVELOPMENT
REQUIREMENTS
• AUTOMOTIVE INDUSTRY
- EFFICIENT COMPLEX-GEOMETRY. MOVING-BOUNDARYCAPABILITIES
- MEMORY/SOLUTION PERFORMANCE FOR LARGESCALE DOMAIN CFO SIMULATION
- DIAGNOSTIC/COMPARATIVE EVALUATIONOBJECTIVES
- GEOMETRIC FIDEUTY AND SPATIAL RESOLUTION AREPRIMARY ACCURACY FACTORS
• AEROSPACE INDUSTRY
- REGULAR AND SMALL-SCALE FLOW DOMAIN (BENCH-MARK EXPERIMENTAL MODELS)
- DESIGN/PERFORMANCE OPTIMIZATION OBJECTIVES
- NUMERICAL AND TURBULENCE MODEL ACCURACYIMPORTANT
- REQUIREMENTS
• HEAT TRANSFER
• LOW REYNOLDS NO. FLOW
• BODY FORCE FIELDS
177
EXTERIOR TUBEREMOVED)
ORIGINAL PAGE IS
OF POOR0UALrrv
OUTLET
SYMMETRY PLANE
MOVING WALLSIMULATION OF GROUNDMOTION RELATNE TOVF.HX:LE (40 _)
MOVING WALLSIMUt.ATION OF ROTATING TIRES(371 RPM)
INLETSIMULATION OF VEHICLETRAVELING AT 40 Imh('T = 30C, P. 100 kPa)
FIGURE 1: EXTERIOR BOUNDARY CONDmONS FOR W202 40 _ ANALYSIS
178
oF eooleOu/ ry
11 De¢93
V1EI.OC r'l"Y MAGNT'RJDE
M/S
ITER= 140
LOCAL MX= 50,.81
LOCAL MN= .0000E+00
15.00
1425
13,50
12.75
12.00
11.25
loJ0
9./S0
II.o00
8.28oi.
7.5C0
e,.'/_o
6.000
S.2_
4,800i
3.700
3.o00
2_50
1.500
.7500
.0G_OE.=,00
W202 UNDERHOOD FLOW AN_J.YSIS
C/_.qE 3:40 _ SIMULATION
VeloCily near the surlace of the vehlde.
W202 UNDERHOOD FLOW ANALYSIS
CASE 3:40 k.ph SIMULATION
179
APPLICATIONS & EXPERIENCES
APPLICATION RNDINGS T.M. NEEDS(DATA}
ROTATING
DISC CAVITY 1
DIFFUSION
HOLE FILM
COOLING 2
FLOW TURBULENCE
COMPLEXITY MODEL
• FORCE FIELD • k-s •
• WALL • 2 LAYER k-t
EFFECT •
• JET-CROSS
FLOW
• WALL
ANISOTROPY
• k-E •
• RNG, k-_
• 2 LAYER k-t
EKMAN LAYER
RESOLVED
FAIRPRESSURE
DROP
EXCESSIVE
E.V.
JET
SEPARATION
SENSITIVE TO
MESH
TOPOLOGY/
RESOLUTION
POOR
SPANWISE
SPREAD
• RSTM +
SUITABLE
2 LAYER
• LOW ReRSTM
• RSTM +
SUITABLE
2 LAYER
• LOW Re
RSTM
1GRABER et al (1987)
2GOLDSTEIN et al (1968), LIGRANI et al (1992)
COMPRESSOR DRUM TEST RIG STAR-CD CONJUGATE HEAT TRANSFER MODEL
AxisOf Rotatlo_"_
180
HALF-CAVI3"_ TEST MODEL: MESH rS TYPICAL FOR MULT-CAVtTY MODEL
¢fs_ tim (r= 11.01n.)
coolant inject=on
Iocabo,n (inlet)
(1.250in.)
last near wan cell ( 0.00026918 In. 0-,¢_)
dl_ bo_ (r - 4.0 In+)
exhaust (ouOm)
lxxe tube O.D. (t = 3.0 In.)
Compressor Drum Test Rig Cold Flow Benchmark Ar;alysis
Secondary F_ow
14-Jun-93
VELOCITY
COMPONENTS U W
FTFoEC
PSYS,= 2
LOCAL MX= 36.44
LOCAL MN= 0.2792E-01
• PRESENTATION GRID"
36.44
33,84
28.64
2O`04
2_44
2O`M
I lL,24
15.6;3
13+00
I0.43
7.831
5.23O
2.6211=
0.27'9_E-01
181
i
Disk 3 Face (z - 0.25 In.)
um m eJ_
_ Drum T_t Rig Cold Row _ _P/IdS
Sec_n_y R0w In Cavity 2
Velocity Ve¢lo_ At r = 7A0 lilies
ii}111
pllllJIIIIII
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IIIII
ll_ t1111
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I
III;IJill!Hi!iII1:!PII III;
I
14-Jun-93
VELOCITY
_ENTS U W
FT/SEC
PSYS= 2
LOCAL MX= 22.30
LOCAL MN_ 0.4491
2230
21,21
20.12
19.03
17.11_
16.84
15.75
14.(B
13.56
12.47
11.3_
Io.28
8_
7.OO6
SJ)13
4.820
3727
2.83S
1.$42
0.4491
CAVITY 2: PRESSURE DROP
u
DI
• . ;
n.ira i --
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i
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Me= o_= ¢lw
DImer-=>loNess Radius Ratio
i ; i
Dbnem,_",less Pressure Drop
STAR-CO Model
• Test Data
Forced Vortex
Free Vortex
182
mQ
n
o
_ -lJm
a$
P
r
o
$
u
r _e
D -Lm
r
o
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CAVITY 4: PRESSURE DROP
f
A
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/
/
/
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4J_ z I I I! F m r m
<u> aim ¢l¢e _ ¢Jm elm iJ_ eJ_
Dlmemskxdess Radius Rs_o
i i
oJm
Pms_re D_o
STAR-CD Model
• Test Data
Fomed Vortex
Free Vortex
1.(_0
1.(00
1.000
_NGLE
.000
DISTANCE
84234
nefk3ed mesh. M = O,S, pipe gdd 8butting plato gMd.
Mesh = 330000 f_ Ceils
Two-Layer mesh
Y
183
HH" .................ItSt', ...............Its,,. ..............Tlls.. .............
,lIII is"#1/1111 • • " .........
x./d - 8
lJtt*N,, ...................llsol.*. ..................If/i/ms. ...............
1_1=4
IKiUH_.I.U/ / ;'/ / / H , , , _ , ,MIA_///.I/J/// / / / s t t,,,,,
/////1111 I" Aii.......P_'fs*l,* ,* s . . •.j,,s_.sss • _. •
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i_,_..,._ ...............
x/el. 20
TII. ................Ii. .................I, ..................'sOl.,_o, ............
• .o,,,#,., ...........
x/d- 16
_,,/sll.. .........
x/d,. 12
5 JulIP4
VEL COMP VW
M/S
LOCAL MX- 36.13
LOCAL MN- .O000E+OO
3O.OO
28.50
-- 27.00
ZS,SO
24.OO
22.5O
21.OO
Ill.50
1LOO
1S.OO "
1&SO
I_.OO
-- 10.S0
O.OOO
-- 7500
-- 8.OOO
-- 3.000
-- 1.500
Y
1_=0.
CFDDlcreteHoleFilmCooUngVed_a_onStudySlmu_atk:,nof experimentofGol_tetn,eL al,(19681;Blowingm,oM ,,0.5Temperature contours off _anwlse planes : 2.1syer model.
=tl,,llO
_1,, I$
x/d= 12
184
| mi
Im
c
o
I
I
n
g
f
e
I
v
e
s
s.im
o
\\ o111 •
\\\ o :\
i
expm'mlenml, z,'d
• 0.0
o 0.25
• 0.5
rl 0.75
• 1.0
," 1.5
0.0
-- 0..25
0.5
0.75
1.0
1.5
o g
0
! • A
x/d
EXPERIMENTS OF GOLDS'T'EIN El" AJ..,1 g_,8
COMPARISON OF FILM COC'UNG EFFECTIVENESS
M - 0.5 : Mesh II.
f .im
I
I
m._
co
I
ns¢g
f
e
Cj_t
I
vn4_o
e
s
s lm
.J_
o
\ •o
\o
\.
-.....• & _ "Jr--..-.-
e_o_nenmL z/d
o 0.0
• 0.5
n 0.75
• 1.0
/, 1.5
-- 0.0
0.25
0.5
0.75
1.0
1,5
0
• • J-
z n 0 _ -"7 n- --r-- ,i -(', _. • _ ro
.o zJee _ 73e0 Io10_ Itl_ iseoo 171oo :lOlem _,.sQ1 _sr_ox/d
EXPERIMENTS OF GOLDS'rEIN E'i" AL,1968
COMPARISON OF FILM COOLING EFFECTIVENESS
M = 0.5 : 2 Layer mesh.
185
APPLICATIONS & EXPERIENCES (cont'd)
APPLICATION
(DATA)
INTERNAL
BLADE
COOLING 3
EXTERNALCAR AERO-
DYNAMICS 4
FLOW
COMPLEXITY
• FORCE FIELD• B.L.
DISRUPTION
• B.L.
STRUCTURE
INTERACTION• COMPLEX
WAKE
TURBULENCE
MODEL
• k-E
• k-s
• RNG k-E
• 2 LAYER k-g
FINDINGS
• DEPENDENCE
ON MESH
RESOLUTION
• GOOD Z_P,h
• DEPENDENCE
ON MESH
RESOLUTION
• GOOD C D• POOR LIFT
T.M. NEEDS
• RSTM
• LOW Re
RSTM
3GE AIRCRAFT ENGINES [ABUAF & KERCHER (1991)]
410 FORD 1/4 SCALE MODELS IN WIND TUNNEL TEST [WILLIAMS et al (1994)]
186
29xugs4
PRESSURE
Nnd"2
LOCAL MX,..4427E_06
LOCN. MN=-.2719E,_06
.4427E+_
.3406E_
.23_E,,06
.1875E_
.13_E_06
.8541E_
• Jr/73E*¢5
-.11ME_
-.laME_
-.22WE_
-2"/lgE*_e
eS_
MAGNITUDE VELOCITY
M/SEC
PSYS,, 2
LOCAL MX- 314.6
LOCAL MN= 4.850
• PRESENTATION GRID"
315.0
294.3
273.7
2S3,0
232.3
211.7
1;)1.0
170.3
149.7
_29.0
"_ 87.6"/
(17.00
46.33
25.87
5.000
187
2_g4H. T. COEFFICIENTS
W I,._Q, METIER - K
LOCAL MX- .10_E_05
LOCAL MN,, .0(X_E+00
.10_E_05
.1014[+05
8314.
?804.
124,1.
S4_
3121.
2341.
780.4
.00_E+00
2._
20¢
lS0
100
LEADING EDGE C_INEL
1! °
. C/D Coa_ A_
0 Ci=O FI_e/¢qi -
FLOWIO° TURN
50 N n n n . n n n n
x/D
]ROOTINLET
CFD BLADE AND LEADING EDGE MODELS
Marinaccio (1989,1990a,1991)
Hp=r¢ 4 a Lcad_g odgc ¢hanndhe._tmm.d'er_t.ion _th d_umccfrom the _¢L Com-par/=o,',of ,,,odd n._-bu]atodcorn,c( mrfac_mad,m=_ =d=/=_= anducrag¢ mca.mrement_w/thbl_," CFD avengepr_
188
THIRD GRID REDUCTION (3:1)
SECOND GRID REDUCTION (2:1)
WAKE REGION
FIRST GRID REDUG'RON (2:1)
NOTCHBACK WIND TUNNEL AERODYNAMIC STUDY MODEL
COMPLETE MODEL DOMAIN
DGRID
02-Jul.93
MAGNITUDE VELOCFr'Y
M/S
LOCAL M.X= 53.46
LOCAL MN= O.0000E+O0
• PRESENTATION GRID"
35.00
3,4.00
33.00
32.00
31.00
30.00
29.00
28.00
27.00
26.00
25.00
24.00
23,00
22.00
21.00
2000
'10.00
15,00
'17.00
'_8.00
1500
WIND TUNNEL AERODYNAMICS STUDY OF NOTCHBACK TEST SHAPE
KE RESULTS - KE TURBULENCE MODEL WITH LUD
VELOCITY MAGNITUDE NEAR THE VEHICLE VIEW FROM REAR
189
PRESSURE COEFFICIENTS AT THE CENTI_:IUN E OF VEHICLE
PRESSI.IRECOEFF1CIEN_AT11'1EClB_TERLINEOFVEI'UCt.E
,.=_'
_,,::. . ;_
o
•e,,il0O4.moo4,_o0 -Lm_ u=__aso _0O.LO000_ _um l.t_. .1
'" .... _.v_ ._-_: ............_i_-_._SS_ c,*_..'.,l._,_'_",':l,'"I
• --I -I¥ I..- I-.'_l_,_b_-,_'-'_____ _ _"_'_ ' I' ]
190
r,N t ,,
. ./_/
o /..too
AL "'= •
o //L /, / TT _
0N ..Ibm
.._ _ n i I E r i J ; a r
EXPERIMENTRESULTS
COMPARISON OF EXPERIMENTAL AND COMFWJlqONAL UFT COEFFICIENTS
K EPSILON llJRBULENCE MOOEL - "" INITIAL RESULTS ""
• SrAncm W,_ON
• N(_HL_X el
• _rC>e._x Cl
O _OTCNL_:X
• FMSTL,_X1
O FLLTL_X Z
• FkSlTL_CX3
O F_.57_A_X4
m _MSI1L_XS_*_£S
, /D .m
c //A
L
C
L , ///_/ /
A
T
I0
. //A I
EXPERIMENTAL RESULTS
COMPARISON OF EXPERIMENTAL AND COMPUTIONAL DRAG COEFFICIENTS
K EPSILON TURBULENCE MODEL - "' INITIAL RESULTS "'°
• _TCHL_X F1
0 _TOL_C m
• Norcm,_<_ c_
0 NO_O,eK_ <_
• _'_I,,KXI
• ;_'rll.,<x
. .
.. o
191
CONCLUSIONS: TURBULENCE MODELINGIMMEDIATE NEEDS
• NEAR-WALL TURBULENCE
- ECONOMICAL, ROBUST LOW REYNOLDSNUMBER 2 EQ. EVM's AND RSTM
- A GENERAL AND VERSATILE NEAR-WALLTREATMENT FOR RSTM
• RSTM MODEL
- ALTERNATIVE CLOSURE OF THE WALLREFLECTION COMPONENT, WITHOUT NEED OFWALL TOPOGRAPHY PARAMETERS
• EDDY-VISCOSITY MODELS
- EXTENSION OF THE NON-LINEAR k-e TOINCORPORATE FORCE-FIELD EFFECTS
• BENCHMARKING
- A RELIABLE DATABASE OF BENCHMARK SET OFREPRESENTATIVE COMPLEX FLOWS
- BENCHMARK PERFORMANCE CLASSIFICATIONOF VARIOUS EVM's (k-s, k-_, RNG AND NON-LINEAR k-_, MULTISCALE EVM's) AND RSTMCLOSURE VARIANTS
CONCLUSIONS: TURBULENCE MODELINGPROGRAM NEEDS
• A LARGER VIEW OF THE RSTM DEVELOPMENT
TOWARDS IMPLEMENTATION IN GENERALCOORDINATE, COMPLEX GEOMETRY DOMAIN,UNSTRUCTURED CFD METHOD
. A BROADER APPLICATION OF DNS TOCOMPLEX FLOWS TO ASSIST TURBULENCEMODEL DEVELOPMENT/OPTIMIZATION
• .WELL-POSED EXPERIMENTAL DATA,OBTAINED IN THE ORIGINAL OR REDUCEDSCALE MODEL OF THE INDUSTRIALCOMPONENT FOR CFD VALIDATION
• COLLABORATIVE INDUSTRY-CFD
RESEARCH/DEVELOPMENT PROGRAMS FOREXPERIMENTATION - CFD VALIDATION
(CALIBRATION) FOR SPECIRC INDUSTRIALAPPLICATIONS
192
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