Drag Prediction for the DLR-F6 configuration using the Tetruss - Nasa

Aircraft Company
Drag Prediction for the DLR-F6 configuration using the
TetrUSS Unstructured Grid CFD Software
Chittur (Venkat) Venkatasubban * & Neal Pfeiffer +
* Principal Engineer, + Principal Engineering Fellow & Manager
Advanced Design
Raytheon Aircraft Company
Wichita, Kansas, USA
Presented at the
3rd AIAA CFD Drag Prediction Workshop
Sponsored by the Applied Aerodynamics TC
2-Day Workshop Preceding the 25th APA Conference
San Francisco, CA
June 3-4, 2006

DPW - 3
Aircraft Company
• Acknowledgements to the TetrUSS team at NASA Langley
– USM3Dns flow solver
� Neal Frink, Paresh Parikh, Mohagna Pandya
– GridTool / Vgrid grid generator
� Shahyar Pirzadeh, Jamshid Samareh
9/26/06 Page 2

DPW - 3
• DLR-F6 Configurations
Configuration
DLR-F6 Wing
Body
DLR-F6 Wing
Body + FX2B
fairing
Grid
Class
Medium
Coarse
Medium
Fine
Tetrahedra
6,483,682
3,142,285
6,284,018
11,521,175
Surface
Triangles
78,540
59,660
80,522
136,710
Boundary layer
cells
z0 = 0.03868 mm
(y+ = 50)
8 layers
z0 = 0.03868 mm
(y+ = 50)
8 layers
z0 = 0.03868 mm
(y+ = 50)
8 layers
z0 = 0.03868 mm
(y+ = 50)
8 layers
8
8
8
8
Aircraft Company
No. of cell
layers across
wing t.e.
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• Vgrid grid generator (Shahyar Pirzadeh et al; NASA Langley)
– Unstructured tetrahedra, using advancing front method
– Element size distribution controlled through field source distributions
Aircraft Company
9/26/06 Page 4

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• USM3Dns flow solver (Neal Frink et al; NASA Langley)
– Cell centered, unstructured tetrahedra
– Implict time stepping
– Spalart Allmaras turbulence model, with wall functions
– Special boundary conditions on blunt wing trailing edges.
Aircraft Company
9/26/06 Page 5

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• Computer Hardware
RAC Beowulf Cluster
Company
Intranet
User
PC or
Unix
System
Front End
Node (xw4100)
2GB RAM
D510s
48 Port Cisco
10/100MB
Network switch
(Private Network)
Aircraft Company
NFS / Compute
Node
(Itanium
64 bit)
Beowulf Cluster
(15 D510 compute nodes
8 D530 compute nodes)
System Each PC (Pentium 4 based) contains 1GB of RAM. Each node has a
100MB network NIC.
Schematic courtesy Everett Schultz, IT Dept., Raytheon Aircraft
D530s
9/26/06 Page 6

DPW - 3
• DLR-F6 + Wing Body
Aircraft Company
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DPW - 3
• DLR-F6 + Wing Body
Medium Grid
Tetrahedra = 6,483,682
Triangles = 78,540
Aircraft Company
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
FS
BL
WL
Original Code + Limiter Original Code; No Limiter
BUB
226.68
-87.57
-5.469
EYE_B
238.383
-66.429
-7.801
EYE_W
234.11
-73.259
-9.16
FS
BL
WL
BUB
222.528
-82.114
-3.724
EYE_B
238.968
-66.705
-7.326
Aircraft Company
EYE_W
235.125
-72.295
-9.677
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
FS
BL
WL
Original Code; No limiter
BUB
222.528
-82.114
-3.724
EYE_B
238.968
-66.705
-7.326
EYE_W
235.125
-72.295
-9.677
FS
BL
WL
Modified Code; No limiter
BUB
224.785
-76.465
-4.279
EYE_B
238.878
-66.697
-7.364
Aircraft Company
EYE_W
236.891
-70.147
-10.665
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
Cp
DLR-F6 + Wing Body
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5, alpha = -0.118
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = - 87.85 mm
Y = -139.87 mm
Y = -194.53 mm
Y = -221.56 mm
Y = -240.37 mm
Y = -300.09 mm
Y = -373.19 mm
Y = -496.02 mm
Aircraft Company
Original Code
+
Limiter
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
Cp
DLR-F6 + Wing Body
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5, alpha = -0.101313
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2
0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = - 87.85 mm
Y = -139.87 mm
Y = -194.53 mm
Y = -221.56 mm
Y = -240.37 mm
Y = -300.09 mm
Y = -373.19 mm
Y = -496.02 mm
Aircraft Company
Modified Code
No Limiter
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
Cp
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
DLR-F6 + Wing Body
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5
Pressure Coefficient (Cp) vs. x/c at Y = -194.53
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
X/C
Y = -194.53 ; Mod; alpha = -0.1013
Y = -194.53; Org; alpha = +0.0136
"Y = -194.53; Org + Limiter; alpha = -0.11838"
Aircraft Company
Comparisons of
Code Variants
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
CD (Total)
0.0295
0.0290
0.0285
0.0280
0.0275
0.0270
0.0265
0.0260
0.0255
DPW-3
DLR-F6 + Wing Body
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
CD (Total) vs. Ncells^(-2/3)
0.0250
0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
Ncells^(-2/3)
Comparisons of Code Variants
• “Modified” Version is preferred to “Original”
• Limiter is not preferred
Modif (4000)
Original (4000)
Original + Limiter
Alpha
0.04
0.02
-0.04
-0.06
-0.08
-0.10
-0.12
-0.14
-0.16
DPW-3
DLR-F6 + Wing Body
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
Alpha vs. Ncells^(-2/3)
Aircraft Company
0.00
Original + Limiter
0.0E+00
-0.02
1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
Ncells^(-2/3)
Modif (4000)
Original (4000)
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DPW - 3
• DLR-F6 + Wing Body (Medium Grid)
Comparisons of Code Variants
• “Modified” Version is preferred to “Original”
• Limiter is not preferred
CM (Total)
-0.1100
-0.1150
-0.1200
-0.1250
-0.1300
-0.1350
-0.1400
-0.1450
-0.1500
DPW-3
DLR-F6 + Wing Body
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
CM (Total) vs. Ncells^(-2/3)
-0.1000
0.0E+00
-0.1050
2.0E+06 4.0E+06 6.0E+06 8.0E+06 1.0E+07 1.2E+07
Ncells^(-2/3)
Modif (4000)
Original (4000)
Original + Limiter
Aircraft Company
9/26/06 Page 15

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Coarse
Tets = 3,142,285
Triangles = 59,660
Medium
Tets = 6,284,018
Triangles = 80,522
Aircraft Company
Fine
Tets = 11,521,175
Triangles = 136,710
9/26/06 Page 16

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Coarse
Tets = 3,142,285
Triangles = 59,660
Aircraft Company
9/26/06 Page 17

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Medium
Tets = 6,284,018
Triangles = 80,522
Aircraft Company
9/26/06 Page 18

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Fine
Tets = 11,521,175
Triangles = 136,710
Aircraft Company
9/26/06 Page 19

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Coarse
Tets = 3,142,285
Triangles = 59,660
Medium
Tets = 6,284,018
Triangles = 80,522
Aircraft Company
Fine
Tets = 11,521,175
Triangles = 136,710
9/26/06 Page 20

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Coarse
Tets = 3,142,285
Triangles = 59,660
Aircraft Company
9/26/06 Page 21

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Medium
Tets = 6,284,018
Triangles = 80,522
Aircraft Company
9/26/06 Page 22

DPW - 3
• DLR-F6 + Wing Body + FX2B Fairing
Fine
Tets = 11,521,175
Triangles = 136,710
Aircraft Company
9/26/06 Page 23

DPW - 3
• DLR-F6 + Wing Body + FX2B (Coarse Grid)
Cp
DLR-F6 + Wing Body + FX2B Fairing
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5, alpha = +0.06752
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = - 87.85 mm
Y = -139.87 mm
Y = -194.53 mm
Y = -221.56 mm
Y = -240.37 mm
Y = -300.09 mm
Y = -373.19 mm
Y = -496.02 mm
Aircraft Company
Wing Pressures
Coarse = 3,142,285 cells
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DPW - 3
• DLR-F6 + Wing Body + FX2B (Medium Grid)
Cp
DLR-F6 + Wing Body + FX2B Fairing
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5, alpha = +0.08757
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = - 87.85 mm
Y = -139.87 mm
Y = -194.53 mm
Y = -221.56 mm
Y = -240.37 mm
Y = -300.09 mm
Y = -373.19 mm
Y = -496.02 mm
Aircraft Company
Wing Pressures
Medium = 6,284,018 cells
9/26/06 Page 25

DPW - 3
• DLR-F6 + Wing Body + FX2B (Fine Grid)
Cp
DLR-F6 + Wing Body + FX2B Fairing
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5, alpha = +0.06752
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = - 87.85 mm
Y = -139.87 mm
Y = -194.53 mm
Y = -221.56 mm
Y = -240.37 mm
Y = -300.09 mm
Y = -373.19 mm
Y = -496.02 mm
Aircraft Company
Wing Pressures
Fine = 11,521,175 cells
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DPW - 3
• DLR-F6 + Wing Body + FX2B
Cp
DLR-F6 + Wing Body + FX2B Fairing
AIAA Drag Prediction Workshop - 3 (June 3-4, 2006)
Mach = 0.75, Re = 5 million, CL = 0.5
Pressure Coefficient (Cp) vs. x/c at various wing spanwise sations
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
X/C
Y = -87.85 ; Fine Grid
Y = -194.53 ; Fine Grid
Y = -87.85; Medium Grid
Y = -87.85; Coarse Grid
Y = -194.53; Medium Grid
Y = -194.53; Coarse Grid
Aircraft Company
Grid Convergence
Coarse = 3,142,285 cells
Medium = 6,284,018 cells
Fine = 11,521,175 cells
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DPW - 3
• DLR-F6 + Wing Body + FX2B
CD (Total)
0.0295
0.0290
0.0285
0.0280
0.0275
0.0270
0.0265
0.0260
0.0255
Comparisons of Code Variants & Grid Convergence
- “Modified” version is preferred to “Original”
- Limiter is not preferred
DPW-3
DLR-F6 + Wing Body + FX2B
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
CD (Total) vs. Ncells^(-2/3)
0.0250
0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
Ncells^(-2/3)
Modif (4000)
Original (4000)
Original + Limiter
ΔCD (No Fairing – FX2B); Medium Grid = 1.06 counts
Alpha
0.20
0.18
0.16
0.14
0.12
0.10
0.08
0.06
0.04
0.02
Modif (4000)
Original (4000)
Original + Limiter
DPW-3
DLR-F6 + Wing Body + FX2B
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
Alpha vs. Ncells^(-2/3)
Aircraft Company
0.00
0.0E+00 1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
Ncells^(-2/3)
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DPW - 3
• DLR-F6 + Wing Body + FX2B
Comparisons of Code Variants & Grid Convergence
- “Modified” version is preferred to “Original”
- Limiter is not preferred
CM (Total)
-0.110
-0.115
-0.120
-0.125
-0.130
-0.135
-0.140
-0.145
-0.150
DPW-3
DLR-F6 + Wing Body + FX2B
Mach = 0.75, CL = 0.5, Re = 5.0 e6,
CM (Total) vs. Ncells^(-2/3)
-0.100
0.0E+00
-0.105
1.0E-05 2.0E-05 3.0E-05 4.0E-05 5.0E-05
Ncells^(-2/3)
Modif (4000)
Original (4000)
Original + Limiter
Aircraft Company
9/26/06 Page 29

DPW - 3
• Lift & Moment curves, Drag Polars (with & without FX2B Fairing)
CL (Total)
CM
DPW-3: DLR-F6 + Wing Body + (FX2B Fairing)
Sref = 0.1454 m2, cref = 141.2 mm, bref/2 = 585.647 mm
Medium Grid : Tets = 6,284,018; Surface Triangles = 80,522
Minf = 0.75, Re = 5x10e6
CL vs. Alpha
0.80
0.00
-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0
-0.160
-0.156
-0.152
-0.148
-0.144
-0.140
-0.136
-0.132
-0.128
CL (Total)
CL (Total) : No Fairing
Alpha (deg)
0.70
0.60
0.50
0.40
0.30
0.20
0.10
DPW-3: DLR-F6 + Wing Body + (FX2B Fairing)
Sref = 0.1454 m2, cref = 141.2 mm, bref/2 = 585.647 mm
Medium Grid : Tets = 6,284,018; Surface Triangles = 80,522
Xref = 157.9 mm, Yref 0.0 mm, Zref = -33.92 mm
Minf = 0.75, Re = 5x10e6
CM vs. CL
-0.124
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80
-0.120
CL (Total)
CM (Total)
CM (Pressure)
CM (Total) : No Fairing
CD
– Slight +ve Alpha shift with FX2B added
– No noticeable change in Drag Polar
– Noticeable decrease in pitch down
moment with FX2B added
0.0440
0.0400
0.0360
0.0320
0.0280
0.0240
0.0200
0.0160
0.0120
0.0080
0.0040
DPW-3: DLR-F6 + Wing Body + (FX2B Fairing)
Sref = 0.1454 m2, cref = 141.2 mm, bref/2 = 585.647 mm
Medium Grid : Tets = 6,284,018; Surface Triangles = 80,522
CD (Total)
Minf = 0.75, Re = 5x10e6
CD vs. CL
CD (Pressure)
CD (Skin Friction)
CD (Total) : No Fairing
0.0000
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80
CL (Total)
Aircraft Company
9/26/06 Page 30

DPW - 3
• Conclusions
– Bubble detected for DLR-F6 + Wing Body
– No Bubble detected for DLR-F6 + Wing Body + FX2B
– Wing trailing edge separation detected with or without FX2B
– Drag reduction: ΔCD (No Fairing – FX2B); Medium Grid = 1.06 counts
– Results obtained under Industrial Conditions!
Aircraft Company
9/26/06 Page 31

DPW - 3
Aircraft Company
• Further work
– Solution adaptive grid refinement using RefineMesh (NASA Langley)
� Uses unique hole creation algorithm (Pirzadeh)
� Generates high quality multilevel grid refinement for unstructured tetrahedra
� Smooth transition between refinement levels
� Improved estimation of wave drag
� Useful in production environment, to reduce grid size & computation time
– Plot Skin Friction Coefficients
9/26/06 Page 32

DPW - 3
•Thanks for your attention
Aircraft Company
9/26/06 Page 33