dlr-f4 results using bombardier aerospace full-aircraft ...mbgrid mesh - an internally generated...
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DLR-F4 Results using Bombardier AerospaceDLR-F4 Results using Bombardier AerospaceFull-Aircraft Full-Aircraft NavierNavier-Stokes Code FANSC-Stokes Code FANSC
Eric Eric LaurendeauLaurendeauEngineering SpecialistEngineering SpecialistAdvanced Aerodynamics, MontrealAdvanced Aerodynamics, Montreal
AIAA CFD Drag Prediction Workshop, Anaheim, CA June 9-10 2001
Josee BoudreauJosee BoudreauAerodynamicistAerodynamicistAdvanced Aerodynamics, MontrealAdvanced Aerodynamics, Montreal
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Outline
• Description of FANSC
• DLRF4 Results:
•Convergence•Pressure Distribution•Forces
• Conclusions
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FANSCFANSC
Developed in House under a multi-year Defense/Industry Research Program which included:
- Development of a grid-generation package (MBGRID)
- Development of structured and unstructured Navier-Stokes methods for full-aircraft configurations
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FANSCFANSC
Flow Solver
- Multi-block structured domain decomposition
- Finite-volume discretization (cell-centered)
- Explicit artificial dissipation (JST, AUSM, CUSP)
- Explicit Runge-Kutta scheme
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FANSCFANSC
Acceleration techniques
- Full-multigrid algorithm
- Local time stepping
- Implicit residual smoothing, directional scaling for high aspect ratio meshes
- Coarse-grain parallelization on blocks (3.6/4 CPU)
- Vectorization (94% efficient)
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FANSCFANSC
Boundary Conditions
- No-Slip/Slip Wall
- Transpiration Wall (Boundary-Layer Coupling)
- Symmetry, Degenerate line/point
- Riemann, Engine Inlet/Outlet
- Multiple boundary condition per block face
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FANSCFANSC
Turbulence Model
- Spalart-Allmaras one-equation with/without wall functions
- Discretized and solved as described in their 1992 paper
- Loosely coupled
- Computed on fine grid only (weighted-average and frozen on coarse grids)
- Zero turbulent eddy viscosity at solid walls on all grid levels
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HardwareHardware
Run-time (for provided mesh)
- 9.0 hours on 4 CPU
- 2.4 Gbytes Memory Requirements
Hardware
- 8-CPU Cray SV1
- 8 Gbytes RAM
- 1.2 Gflops/CPU
-
-
-
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DLR-F4 Results: Convergence (DLR-F4 Results: Convergence (DPW gridDPW grid))
Iterations
log(
Res
ρ)
0 250 500 750 1000-6
-5
-4
-3
-2
-1
0
Constant αConstant CL
Iterations
CL
0 250 500 750 10000
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Constant αConstant CL
Iterations
CD
0 250 500 750 10000
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
Constant αConstant CL
Iterations
log(
nut)
0 250 500 750 1000-5
-4
-3
-2
-1
0
1
Constant αConstant CL
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DLR-F4 Results (M 0.60 CL 0.50)DLR-F4 Results (M 0.60 CL 0.50)
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 18.5%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 23.8%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 33.1%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 40.9%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 51.2%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 63.6%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 84.4%
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DLR-F4 Results (M 0.80 CL 0.50)DLR-F4 Results (M 0.80 CL 0.50)
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 18.5%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 23.8%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 33.1%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 40.9%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 51.2%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 63.6%
x/c
Cp
0 0.25 0.5 0.75 1
-1.50
-1.00
-0.50
0.00
0.50
1.00
EXPFANSC
η = 84.4%
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DLR-F4 Results (M 0.75 DLR-F4 Results (M 0.75 α α = 1.0 = 1.0 degdeg.).)
Oil flowTrailing edge separation and corner vortex
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MBGRID meshMBGRID mesh
- An internally generated mesh of the DLRF4 configuration using Bombardier Aerospace MBGRID grid-generation package was produced:
Orthogonality of the mesh on the body surface
10e-6 wall spacing
3 Million mesh points, open wing-tip, blunt trailing edge
- Similar convergence as when the DPW mesh is used
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DLR-F4 Results (M 0.75)DLR-F4 Results (M 0.75)
αo
CL
-4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.00
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Exp NLRExp ONERAExp DRAFANSC-DPW gridFANSC-Bombardier grid
The solid line prediction lies in line with the most accurate unstructured CFD results presented at the DPW.
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DLR-F4 Results (M 0.75)DLR-F4 Results (M 0.75)
CL
Cm
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0-0.2
-0.19
-0.18
-0.17
-0.16
-0.15
-0.14
-0.13
-0.12
-0.11
-0.1
-0.09
-0.08
-0.07
-0.06
Exp NLRExp ONERAExp DRAFANSC-DPW gridFANSC-Bombardier grid
The solid line prediction lies in line with the most accurate unstructured CFD results presented at the DPW.
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DLR-F4 Results (M 0.75)DLR-F4 Results (M 0.75)
CD
CL
0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.100
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Exp NLRExp ONERAExp DRAFANSC-DPW gridFANSC-Bombardier grid
The solid line prediction lies in line with the most accurate unstructured CFD results presented at the DPW.
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CONCLUSIONSCONCLUSIONS
- FANSC showed excellent convergence characteristics (density and turbulent viscosity) on the required grid, despite its excessive skewness
- Integrated lift and pitching moment predictions on the required grid were accurate, but mesh skewness introduced discretization errors on the skin-friction evaluations (Pressure drag was correctly predicted)
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CONCLUSIONSCONCLUSIONS
- Results obtained with FANSC on an internally generated mesh using the MBGRID grid-generation package resulted in accurate lift, pitching moment and drag prediction, as was expected from our
industrial experience.
- The overall performance of FANSC in terms of robustness, convergence and accuracy at this drag workshop ranks it as one of the best Navier-Stokes code available.
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CONCLUSIONSCONCLUSIONS
- It was unfortunate that the DPW structured mesh was not better suited for the problem in hand.
However, it did provide a basis for evaluating the robustness of the structured codes.
- The enthusiasm present at the workshop was very encouraging and demonstrated the need to pursue further research in this area.
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CONCLUSIONSCONCLUSIONS
- Bombardier Aerospace whishes to thank the DPW committee for their efforts in organizing the event.