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October 7, 2018, 10:14 |
Compression instead of expansion
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#1 |
New Member
Enrico De Filippi
Join Date: Jul 2018
Location: Brescia, Italy
Posts: 14
Rep Power: 8 |
Hi everybody, I'm simulating an axial turbine with mixing plane and real gas. As you know, a turbine expand the gas, but in my simulation there are zones in which the gas is higly compressed ( so non-physical results). Do you have any hint on how to solve this or how to control? Maybe, i've put wrong boundary condition. Here are the 0/ files:
alphat dimensions [1 -1 -1 0 0 0 0]; internalField uniform 0; boundaryField { Inflow_stator { type calculated; value uniform 0; } Outflow_stator { // type mixingPlaneFvPatchField: type mixingPlane; value $internalField; } Wall_stator { type alphatWallFunction; Prt 0.741; value uniform 0; } Perio_stator { type cyclic; value uniform 0; } Inflow_rotor { // type mixingPlaneFvPatchField: type mixingPlane; value $internalField; } Outflow_rotor { type calculated; value uniform 0; } Wall_rotor { type alphatWallFunction; Prt 0.741; value uniform 0; } Perio_rotor1 { type cyclic; value uniform 0; } Perio_rotor2 { type cyclic; value uniform 0; } } epsilon dimensions [0 2 -3 0 0 0 0]; internalField uniform 10000; boundaryField { Inflow_stator { type fixedValue; value uniform 2000; } Outflow_stator { type mixingPlane; value $internalField; } Wall_stator { type compressible::epsilonWallFunction; refValue uniform 0; value $internalField; Cmu 0.09; kappa 0.41; E 9.8; } Perio_stator { type cyclic; value $internalField; } Inflow_rotor { type mixingPlane; value $internalField; } Outflow_rotor { type inletOutlet; inletValue $internalField; value 13450; } Wall_rotor { type compressible::epsilonWallFunction; refValue uniform 0; value $internalField; Cmu 0.09; kappa 0.41; E 9.8; } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } i dimensions [0 2 -2 0 0 0 0]; internalField uniform 27000; boundaryField { Inflow_stator { type fixedValue; value $internalField; } Outflow_stator { // type mixingPlaneEnthalpyJump; // patchType mixingPlane; type mixingPlane; rotating false; value $internalField; } Perio_stator { type cyclic; value $internalField; } Wall_stator { type gradientEnthalpy; gradient uniform 0; value uniform 463864; } Inflow_rotor { // type mixingPlaneEnthalpyJump; // patchType mixingPlane; type mixingPlane; rotating true; value $internalField; } Wall_rotor { type gradientEnthalpy; gradient uniform 0; value $internalField; } Outflow_rotor { type inletOutlet; inletValue $internalField; value $internalField; } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } k dimensions [0 2 -2 0 0 0 0]; internalField uniform 5; boundaryField { Inflow_stator { type fixedValue; value 0.4; } Outflow_stator { type mixingPlane; value $internalField; } Wall_stator { type compressible::kqRWallFunction; value $internalField; } Perio_stator { type cyclic; value $internalField; } Inflow_rotor { type mixingPlane; value $internalField; } Outflow_rotor { type inletOutlet; inletValue $internalField; value $internalField; } Wall_rotor { type compressible::kqRWallFunction; value $internalField; } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } p dimensions [1 -1 -2 0 0 0 0]; internalField uniform 400000; boundaryField { Inflow_stator { type totalPressure; phi phi; rho none; psi psi; U U; gamma 1.4; p0 uniform 5.1e5; value $internalField; } Outflow_stator { type mixingPlane; rotating false; value $internalField; } Wall_stator { type zeroGradient; } Perio_stator { type cyclic; value $internalField; } Inflow_rotor { type mixingPlane; rotating true; value $internalField; } Outflow_rotor { type fixedValue; value uniform 300000; } Wall_rotor { type zeroGradient; } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } T dimensions [0 0 0 1 0 0 0]; internalField uniform 330; boundaryField { Inflow_stator { type totalTemperature; phi phi; rho rho; psi psi; U U; gamma 1.4; T0 uniform 338; value $internalField; } Outflow_stator { // type mixingPlaneEnthalpyJump; // patchType mixingPlane; type mixingPlane; rotating false; value $internalField; } Wall_stator { type zeroGradient; } Perio_stator { type cyclic; value $internalField; } Inflow_rotor { // type mixingPlaneEnthalpyJump; // patchType mixingPlane; type mixingPlane; rotating true; value $internalField; } Outflow_rotor { type zeroGradient; value $internalField; } Wall_rotor { type zeroGradient; } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } U dimensions [0 1 -1 0 0 0 0]; internalField uniform (0 0 100); boundaryField { Inflow_stator { type pressureDirectedInletVelocity; inletDirection uniform (0 0 1); value uniform (0 0 0); } Outflow_stator { type mixingPlane; rotating false; value $internalField; } Wall_stator { type fixedValue; value uniform (0 0 0); } Perio_stator { type cyclic; value $internalField; } Inflow_rotor { type mixingPlane; rotating true; value $internalField; } Outflow_rotor { type pressureInletOutletVelocity; inletValue $internalField; value $internalField; } Wall_rotor { type fixedValue; value uniform (0 0 0); } Perio_rotor1 { type cyclic; value $internalField; } Perio_rotor2 { type cyclic; value $internalField; } } These are the results after 5000 iterations: Flux divergence min = 4.28614548132e-05 max = 24180860.2673 average: 15406.0985031 Writing divFlux field Mach number min = 0.00198878622956 max = 4.35597144753 Writing Mach number field Field U magnitude min = 0 max = 1000 Field p min = 49202.4992467 max = 1055827.15616 Field rho min = 1.52104950445 max = 27.9890057068 Field T min = 337.498873263 max = 1163.72657359 Mixing plane pair (Outflow_stator, Inflow_rotor) : 0.756677749244 -0.757134457367 Diff = -0.00045670812309 or 0.0603570177062 % End max U should be around 160 m/s and max T and p should be around the ones at the inlet. Any hint would be appreciated. Thanks in advance. |
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October 8, 2018, 11:19 |
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#2 |
Super Moderator
Tobias Holzmann
Join Date: Oct 2010
Location: Bad Wörishofen
Posts: 2,711
Blog Entries: 6
Rep Power: 52 |
Hi, please edit your post and use code tags. No one will go through a not formatted text, at least I don´t
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Keep foaming, Tobias Holzmann |
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