implementation of a domain scaling approach for...
TRANSCRIPT
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Institute for Flight Propulsion Technische Universität München
Implementation of a DomainScaling Approach for
Turbomachinery Computationsin OpenFOAM
Oliver Borm, Fethi Tekin, Hans-Peter Kau
Institute for Flight PropulsionTechnische Universität München
2010-06-23
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 1/22
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Institute for Flight Propulsion Technische Universität München
Outline
Introduction
Implementation
Results
Conclusion and Outlook
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 2/22
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Institute for Flight Propulsion Technische Universität München
Outline
Introduction
Implementation
Results
Conclusion and Outlook
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 3/22
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Institute for Flight Propulsion Technische Universität München
Domain Scaling Method
TR
T'S 2 T'x S = TR
TR
2 T'x S = TR
Domain Scaling
Frozen Rotor
Rotor Stator Interfaces
• Domain Scaling– Identical pitch for each blade row– Least common denominator
simulated– Pitch-wise periodicity– Time varying position of rotor and
stator blade is resolved(unsteady)
• Frozen Rotor– Solution is position dependent
(steady)
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 4/22
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Institute for Flight Propulsion Technische Universität München
Periodicity
overlapGgi Interface
Inlet
Walls
Outlet
• Periodicity ensures physicalcorrectness and numericalstability
• Duplicated velocity profile ofslave (dashed blue line)conflicts with profile of master(red line) at overlapGgiinterface
• Jump in profile at uncoveredpart of interface
• Even if numerics allow thatsetup, it crashes at run time!
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 5/22
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Institute for Flight Propulsion Technische Universität München
Outline
Introduction
Implementation
Results
Conclusion and Outlook
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 6/22
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Institute for Flight Propulsion Technische Universität München
Main Problem - Partial Uncovered Patches
A A
BB
1 2
1 2
z
A1 ⇐⇒ A2 and B1 ⇐⇒ B2
• Implementation based onoriginal overlapGgi interface
• Two partially uncoveredcoupled patches
• Expansion of both patches tocover 360° full circumferentialsurface
• No face left uncovered• Ggi interpolation between these
two surfaces
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 7/22
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Institute for Flight Propulsion Technische Universität München
New overlapGgi Boundary File Definition
interface1{
type overlapGgi;nFaces 200;startFace 50400;shadowPatch interface2;rotationAxis (0 0 1);n 12; // number of passages in this blade row
}
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 8/22
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Institute for Flight Propulsion Technische Universität München
Finite Volume Dynamic Mesh Handling
turboFvMesh
1. Dynamic mesh handling required for unsteady cases
2. No change in mesh topology during simulation⇒ no mesh motion3. Arbitrary number of blade rows treated as separate cell zones
4. Possibility to extract each blade row from internal mesh duringpost-processing
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 9/22
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Institute for Flight Propulsion Technische Universität München
turboFvMesh Setup
turboFvMesh
1. Splitting mesh into cell sets for every blade row using regionCellSets
2. Cell sets⇒ cell zones3. Individual definition of rpm for each cell zone
4. Counter rotating multistage turbomachinery simulations possible
Caution!
• Same rotational origin and axis for all zones• Cylindrical coordinate system in dictionary file• Rotational direction determined by sign of rpm
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 10/22
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Institute for Flight Propulsion Technische Universität München
turboFvMesh dynamicMeshDict DefinitiondynamicFvMesh turboFvMesh;turboFvMeshCoeffs{
coordinateSystem{
type cylindrical;origin (0 0 0);axis (0 0 1);direction (1 0 0);
}rpm{
rotor_1 60;stator_1 0;rotor_2 -120;stator_2 0;
}}
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 11/22
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Institute for Flight Propulsion Technische Universität München
Compressible Dynamic Mesh Solver without Mesh Motion
sonicTurbDyMFoam
• Required due to lack of suitable solver• Based on sonicTurbFoam and sonicFoamAutoMotion• Replaced motionSolver library with dynamicFvMesh library, more
suitable as internal mesh topology does not change
• Adjustable global time step based on CFL Number
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 12/22
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Institute for Flight Propulsion Technische Universität München
Outline
Introduction
Implementation
Results
Conclusion and Outlook
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 13/22
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Institute for Flight Propulsion Technische Universität München
Incompressible Generic Test Case
Description
• Radial inlet velocity of 10 ms• Constant pressure at outlet• Gap between rotor and
stator with cyclicGgi atsides
• Remaining boundariesconsist of solid walls
• Solver: icoFoam andicoDyMFoam
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 14/22
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Institute for Flight Propulsion Technische Universität München
Incompressible Steady Case
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 15/22
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Institute for Flight Propulsion Technische Universität München
Incompressible Steady Case - Transformed
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 16/22
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Institute for Flight Propulsion Technische Universität München
Incompressible Unsteady Cases
Single Rotating Rotor Counter Rotating Rotors
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 17/22
icoDymFoam.aviMedia File (video/avi)
counter.aviMedia File (video/avi)
./animations/icoDymFoam.avi./animations/counter.avi
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Institute for Flight Propulsion Technische Universität München
Axial Compressor Test Case
Rotor Stator
Outlet
Inlet
overlapGgiInterface
• Rescaled axial compressor stage for domain scaling interface
• Pitch angle ∼= 15.6522° (conform to 23 rotor and stator passages)
• Constant static pressure at outlet: 95000Pa
• Inlet: U/|U | = (0 0 1); pt = 101325Pa; Tt = 293KIntroduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 18/22
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Institute for Flight Propulsion Technische Universität München
Unsteady Domain Scaling
Unsteady Domain Scaling
• Aforementioned sonicTurbDyMFoam
• Operating point near stall
• S1 surface at approx. 70% span
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 19/22
ds_omega_full.aviMedia File (video/avi)
./animations/ds_omega_full.avi
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Institute for Flight Propulsion Technische Universität München
Steady Frozen Rotor
• sonicTurbFoam due to problems with MRF solver
• Stage acts like a tandem stator
• Huge deflection⇒ bad efficiencyIntroduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 20/22
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Institute for Flight Propulsion Technische Universität München
Outline
Introduction
Implementation
Results
Conclusion and Outlook
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 21/22
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Institute for Flight Propulsion Technische Universität München
Conclusion and Outlook
Current Status
• Domain Scaling and Frozen Rotor approaches applicable with newoverlapGgi interface
• Parallelization works rarely
Outlook
• Full parallelization• GAMG solver for overlapGgi interface• Phaselag rotor-stator interface based on modified cyclicGgi and
overlapGgi
Introduction Implementation Results Conclusion and Outlook
O. Borm, F. Tekin, H.-P. Kau, Institute for Flight Propulsion Implementation of a Domain Scaling Approach for Turbomachinery Computations in OpenFOAM – 22/22
IntroductionImplementationResultsConclusion and Outlook