Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Transcript of Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
http://slidepdf.com/reader/full/draft-tube-calculations-using-openfoam-15dev-and-validation-with-flindt-data 1/26
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Draft Tube calculations using OpenFOAM-1.5devand validation with FLINDT data
C. Devals, Y. Zhang and F.GuibaultÉcole Polytechnique de Montréal, Canada
T. Vu and B. NennemannAndritz Hydro, Pointe-Claire, Canada
6th OpenFOAM Workshop, June 13-16 2011, PennState University, USA
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Viscous flow simulations for hydraulic turbo-machinery design
Runner
Draft-tube
Spiralcasing
Context
Distributor
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
http://slidepdf.com/reader/full/draft-tube-calculations-using-openfoam-15dev-and-validation-with-flindt-data 3/26
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Previous work: 25th IAHR Symposium on Hydraulic Machinery and Systems
September 20-24, 2010, Timisoara, Romania Steady and unsteady flow computation in an elbow draft tube with
experimental validationT.C. Vu, C. Devals, Y. Zhang, B. Nennemann and F. GuibaultInternational Journal of Fluid Machinery and SystemsVol 4, No 1, January-March 2011
Context
Lt=0.5%DthLt=1%Dth Lt=0.25%Dth
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Understand why the recovery coefficient for Phi=0.368 shows an importantdecrease for Lt=0.5%Dth.
Validate OpenFOAM RANS simulations for draft tube on hexahedralmeshes
Compare recovery coefficient χ prediction with experimental data
Objectives
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Model draft tube test: FLINDT FLINDT is for FLow INvestigation in Draft Tubes Project (LMH-EPFL Switzerland) Throat diameter: Dth = 0.4 m Rotational speed: N=1000 RPM
Angular velocity: ϖ=104.66 Hz
Flow coefficient ϕ: 0.340, 0.360, 0.368, 0.380, 0.390 and 0.410
corresponding swirl: 0.332, 0.242, 0.214, 0.198, 0.149 and 0.076
Recovery coefficient
∆pstat static pressure difference between inlet andoutlet
Aref reference section area Aref=0.17538m2
Test Case Description
3
th R
Q
πϖ ϕ =
2
2
1
∆=
ref
stat
A
Q
P
ρ
χ
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Steady state Reynolds averaged Navier-Stokes equations
Newtonian fluid
turbulence model
126
1
10.89257.0
kg.m997
−−
−
==
=
smlam ρ
µ ν
ρ
ε −k
turblam
T
U
U U I p
U U
ν ν ν
ν ρ
+=
=⋅∇
∇+∇+−⋅∇=⊗⋅∇
0
))(()(
r
rrrr
Physical Properties and Models
ρ ε
ρ
µ ν
2k C muturbturb ==
lam
turbrel
µ
µ µ =
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Boundary Conditions
Inletpressure
type zeroGradient
U, k
type profile1DfixedValue
fileName "profil-rr.csv"
epsilontype
turbulentMixingLengthDissipationRateInlet
mixingLength 0.0003285
U profile k profile
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Boundary Conditions
Outletpressure
type fixedMeanValuemeanValue 0
value uniform 0
U, k and epsilon
type zeroGradient
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Boundary Conditions
pierU
type fixedValue
value uniform (0 0 0)
p, k and epsilon
type zeroGradient
No slip Wall condition
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Boundary Conditions
mainU
type fixedValue
value uniform (0 0 0)
p, k and epsilon
type zeroGradient
No slip Wall condition
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Boundary Conditions
extU
type fixedValue
value uniform (0 0 0)
p, k and epsilon
type zeroGradient
No slip Wall condition
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Steady state (RANS) calculations (10000 iterations) Solver: SimpleFOAM Convection term discretization: normalized variable diagram (NVD)
scheme GammaV (between 0 and 1) Linear solver: PBiCG for all variables except P,
GAMG for P Turbulence model: k-epsilon Velocity inlet BC : axi-symmetrically averaged velocity measures Turbulence inlet BC: axi-symmetrically averaged k measures
4 turbulence length scales tested (epsilon) Convergence: tolerance of 1.e-6, relTol of 0.01 for all variables
Monitoring variable: pressure recovery factor
Numerical Model
2
2
1
∆=
ref
stat
A
Q
P
ρ
χ
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation
Scheme GammaV investigation: ψ =0, ψ =0.5 and ψ =1GammaV is the improved version of the NVD gamma scheme(ψ =0 best accuracy and ψ =1 more robust)
Mixing length investigation: Lt=0.25%Dth, 0.5%Dth, 1.0%Dth and 5%Dth
Initial conditions investigation
Test Cases
# nodes # elements
CRS 288744 276560
STD 782283 757968
FINE 1875470 1830884
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation
Scheme GammaV investigation
Mixing length investigation
Initial conditions investigation
Test Cases
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation – GammaV 1
Standard mesh Fine meshCoarse mesh
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation – GammaV 1
Standard meshCoarse mesh Fine mesh
Phi=0.368
X=-0.25
Phi=0.380
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation – GammaV 1 – Phi=0.380
StaticPressure
AxialComponent
RadialComponent
Energy
TangentialComponent
CFDExperimental Data
Steady probe CFDExperimental Data
Steady probe
Fine meshCoarse mesh
202
207203
205
209
208
213
211 214
ct2ct1
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation
Scheme GammaV investigation
Mixing length investigation
Initial conditions investigation
Test Cases
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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GAMMAV 0.5 GAMMAV 1.0GAMMAV 0.0
Scheme investigation – GammaV – Coarse mesh
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation
Scheme GammaV investigation
Mixing length investigation
Initial conditions investigation
Test Cases
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mixing length investigation – Standard mesh – GammaV 1
Lt=0.25%Dth Lt=0.50%Dth Lt=1.00%Dth Lt=5.00%Dth
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Relative Viscosity – Lt=0.50%Dth Relative Viscosity – Lt=5.00%Dth
X=0.25
X=-0.20
X=-0.25
X=0.20
X=0.25
X=-0.20
X=-0.25
X=0.20
X=0.00 X=0.00
Mixing length investigation – Standard mesh – GammaV 1
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Mesh investigation
Scheme GammaV investigation
Mixing length investigation
Initial conditions investigation
Test Cases
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Initial condition investigation – Std mesh – GammaV 1 – Lt=0.25%Dth
Initial conditionsfrom no previous calculation
Initial conditionsfrom previous calculation
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Conclusions
Results are quite good compared to experimental data Results are not so sensitive to mesh resolution except for Phi=0.368 Results are sensitive to scheme Results are sensitive to initialization
Perspectives
Validation and comparison with OpenFOAM-1.6ext Runner and Draft-Tube calculations Unsteady cases Wall function investigation
Conclusions and Perspectives
7/15/2019 Draft Tube Calculations Using OpenFOAM-1.5dev and Validation With FLINDT Data
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Thank you for your listening
Any questions?