Hydraulic turbine distributor simulation
using OpenFOAM
Fifth OpenFOAM Workshop, June 21-24 2010, Gothenburg, Sweden
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F.Guibault, C. Devals and J-F DubéÉcole Polytechnique de Montréal, Canada
T. Vu and B. NennemanAndritz Hydro, Pointe-Claire, Canada
Context
Viscous flow simulations for hydraulic turbomachinery design
Spiral
Stator
Rotor
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Runner
Draft-tube
Spiral casing
Distributor
Objectives
• Validate OpenFOAM RANS simulations for distributor blade passage in tandem mode on hybrid meshes
• Validate periodic boundary conditions• Predict torque on guide vanes for the full range of blade
openings• Compare torque prediction with experimental data
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• Compare torque prediction with experimental data
Model turbine test – Medium head Francis turbine
� Throat diameter: Dth = 0.35 m� Test case: 24 wicket gates, 24 stay vanes� Casing type: piguet� Tested turbine head: H = 30 m� Wicket gate opening angles: 14 deg, 20 deg, 25 deg, 30 deg and 42 deg.� Distributor inflow angles: 35 ± 5deg
Test case description
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� Steady state Reynolds averaged Navier-Stokes equations
Physical properties and Models
1kg.m997 −=ρ
turblam
T
U
UUIp
UU
ννν
νρ
+=
=⋅∇
∇+∇+−⋅∇=⊗⋅∇
0
))(()(
r
rrrr
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�Newtonian fluid
� steady-state case (5000 iterations)
� turbulence model
126
1
10.89257.0
kg.m997
−−
−
==
=
smlamρ
µν
ρ
ε−k
Outlet
cyclicGgi
empty
wall
Boundary conditions
Inlet velocity profile
� Constant cylindrical values →
implemented using profile1DfixedValuePeriodicity boundary conditions
� Implemented using GGI (General Grid
Interface)
Turbulence boundary conditions
� Turbulent kinetic energy intensity and
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Inlet
cyclicGgi
empty
� Turbulent kinetic energy intensity and
mixing length
Boundary conditions
[Name]Profil radial
[Spatial Fields]R
[Data]R [ m ], Velocity Axial [ m s^-1 ], Velocity Radial [ m s^-1 ], Velocity Circumferential [ m s^-1 ]0.0000000, 0.0, -1.959806, 3.3944840.2865129, 0.0, -1.959806, 3.3944840.2865130, 0.0, -1.959806, 3.3944840.2865160, 0.0, -1.959806, 3.3944840.2865161, 0.0, -1.959806, 3.394484
Velocity.cvs file:
Inlet for U
type profile1DfixedValue;fileName "velocity.csv";fileFormat "turboCSV";interpolateCoord "R";fieldName "Velocity";fieldScaleFactor 1;value uniform (0 0 0);
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0.2865161, 0.0, -1.959806, 3.394484
Inlet for epsilon
type turbulentMixingLengthDissipationRateInlet;mixingLength 0.000849; value $internalField;
Inlet for k
type turbulentIntensityKineticEnergyInlet;intensity 0.02;value $internalField;
Solvers
For p: GAMG� tolerance 1e-06� relTol 0.01� smoother GaussSeidel� cacheAgglomeration true� nCellsInCoarsestLevel 100
SIMPLE� nNonOrthogonalCorrectors 0� pRefCell 0� pRefValue 0� pMin pMDin [1 -1 -2 0 0 0 0] 100
relaxationFactors� p 0.3
FvSolution
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� nCellsInCoarsestLevel 100� agglomerator faceAreaPair� mergeLevels 1
For U k epsilon: PBiCG� preconditioner DILU� tolerance 1e-05� relTol 0.1
� p 0.3� U 0.7� k 0.7� epsilon 0.7
FvSchemes
ddtSchemes� default steadyState;gradSchemes� default Gauss linear� grad(p) Gauss linear� grad(U) Gauss linear
divSchemes� default none
laplacianSchemes� default none� laplacian(nuEff,U) Gauss linear corrected� laplacian((1|A(U)),p) Gauss linear corrected� laplacian(DkEff,k) Gauss linear corrected� laplacian(DepsilonEff,epsilon) Gauss linear corrected� laplacian(DREff,R) Gauss linear corrected� laplacian(DnuTildaEff,nuTilda) Gauss linear corrected
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� div(phi,U) Gauss GammaV 1� div(phi,k) Gauss upwind� div(phi,epsilon) Gauss upwind� div(phi,R) Gauss upwind� div(R) Gauss linear� div(phi,nuTilda) Gauss upwind� div((nuEff*dev(grad(U).T()))) Gauss linear
corrected
interpolationSchemes� default linear� interpolate(U) linear
snGradSchemes�default corrected
fluxRequired�default no
p
Structured/unstructured (hybrid) mesh
� Automatic near-blade domain partitioning
� Structured mesh generation in near-blade
region
� Periodic surface optimization based on
minimum and maximum opening angles
� Delaunay-based unstructured mesh generation
Mesh generation
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� Delaunay-based unstructured mesh generation
� Unstructured mesh adaptation in flow passage
� OpenFOAM import through CGNS standard file
forma
Small opening Large opening
Opening of the wicket gate
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Exemple of convergence: wg42in35
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Experimental-CFD Comparison
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Conclusions and Perspectives
Conclusions
� “Relatively universal” numerical setup that provides robust results over the range of distributor operating conditions,
� Convergence stagnation to a level that provides satisfactory numerical results
� Validation of several types of boundary conditions, including cyclicGGI,� Results correlate very well with experimental measurements
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Perspectives
� Complete automation of case setup and post-processing� Unsteady flow simulations� Shape optimization
Special Thanks:
Maryse Page from IREQ/Hydro QuébecYing Zhang from from École Polytechnique de Montréal
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Ying Zhang from from École Polytechnique de Montréal
for their help