Numerical prediction of the flow around a marine...
Transcript of Numerical prediction of the flow around a marine...
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical prediction of the flow around amarine propeller
Mitja Morgut
Department of Naval Architecture,Ocean and Environmental Engineering, DINMA
University of TriesteTrieste, Italy
September 14, 2009
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Outline
1 IntroductionRoad Map
2 Propeller in Uniform FlowNumerical MethodComputational DomainsResultssimpleSRFFoam
3 Cavitation ModellingMyRASinterPhaseChangeFoamFull Cavitation Model
4 Conclusions
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Road Map
Introduction
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Road Map
Road Map
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical MethodComputational DomainsResultssimpleSRFFoam
Propeller in Uniform Flow
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical MethodComputational DomainsResultssimpleSRFFoam
Numerical Method
The developed CFD procedure:
considers only one passage bladeemploys a MFR (Multiple Frame of Reference) approachmeshes are generated using ANSYS ICEM CFD 11calculations are performed with MRFSimpleFOAMturbulence is modelled using SpalartAllmaras model
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical MethodComputational DomainsResultssimpleSRFFoam
Computational DomainsIn this case simulations were performed using two different computational domains:
DOMAIN ARotating Fixed
Hmid 0.17DLmid 0.76D
L1 1.5DL2 5DH2 1.38D
DOMAIN BRotating Fixed
Hmid 0.17DLmid 0.76D
L1 1.5DL2 5DH2 4.3D
D = Diameter of the Propeller
Lmid = Length of part Rotating
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical MethodComputational DomainsResultssimpleSRFFoam
Propeller E779a
0.0 0.2 0.4 0.6 0.8 1.0 1.20.0
0.5
1.0
J
KT
, 10K
Q
KT
10KQ
Exp. DataMRF Domain AMRF Domain B
ε(KT )% =KT ,NUM−KT ,EXP
KT ,EXP· 100
ε(KQ )% =KQ,NUM−KQ,EXP
KQ,EXP· 100
Domain A Domain BJ εKT (%) εKQ (%) εKT (%) ε(KQ )(%)
0.249 14.30 10.82 -4.95 -1.410.498 13.40 10.33 -3.87 1.210.596 12.00 7.46 -3.12 1.350.695 13.12 5.45 -3.71 1.760.845 4.55 -3.90 4.55 1.260.946 -4.67 -10.93 -9.96 2.14
The INSEAN E779A Propeller Dataset,INSEAN Propulsion and Cavitation Laboratory, 2006
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Numerical MethodComputational DomainsResultssimpleSRFFoam
SimpleSRFFoam
Simulation on Domain A
Suction Side Pressure Side
Comment: Pressure distribution completely wrong. (J=0.695)
Simulation on Domain BUnder Investigation
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Cavitation Modelling
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
MyRASinterPhaseChangeFoamIn momentum equation, subgrid viscosity (µS) replaced by turbulent viscosity (µt )
interPhaseChangeFoam MyRASinterPhaseChangeFoam
surfaceScalarField muf =twoPhaseProperties->muf()+ fvc::interpolate(rho*turbulence->nuSgs());
surfaceScalarField muEff =(muEff,twoPhaseProperties->muf()+ fvc::interpolate(rho*turbulence->nut()));
fvVectorMatrix UEqn(fvm::ddt(rho, U)+ fvm::div(rhoPhi, U)- fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)- fvm::laplacian(muf, U)- (fvc::grad(U) & fvc::grad(muf)));
fvVectorMatrix UEqn(fvm::ddt(rho, U)+ fvm::div(rhoPhi, U)- fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U)- fvm::laplacian(muEff, U)- (fvc::grad(U) & fvc::grad(muEff)));
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Full Cavitation Model, TheoryThe momentum conservation equation for the mixture is:
∂
∂t(ρm−→v m) +∇ · (ρm
−→vm−→v m) = −∇p +∇ · [µm(∇−→v m +∇−→v T
m)] + ρm−→g +
−→F (1)
The mass conservation equation for the mixture
∂
∂t(ρm) +∇ · (ρm
−→v m) = 0 (2)
The ρm − fv (Mixture density - vapour mass fraction) relationship
1ρm
=fvρv
+1− fvρl
(3)
The vapour phase (αv ) volume fraction
αv = fvρm
ρv= 0 (4)
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Full Cavitation Model, Theory
The trasport equation for the vapour mass fraction fv
∂
∂t(ρmfv ) +∇ · (ρm
−→v mfv ) = ∇ · (Γ∇fv ) + Re − Rc (5)
The source terms:8>>><>>>:Re = Ce
Vchγρlρv
q23
pv−pρl
(1− fv ), when p < pv
Rc = CcVchγρlρl
q23
p−pvρl
fv ,when p > pv(6)
Vch =√
k , Ce = 0.02, Cc = 0.01 (7)
Singhal, A.K., et. al., 2002, Mathematical Basis and Validation of the Full CavitationModel, J. Fluids Eng., 124, pp. 617-623
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Full Cavitation Model, Implementation, MyFCM
In the solver interFoam, the GammaEqn.H was replaced by the trasport equation forthe vapour mass fraction, (Eqn. (2)). The mixture density is computed using Eqn. (3).
fvScalarMatrix fEqn(fvm::ddt(rho, f)+ fvm::div(rhoPhi, f)- fvm::laplacian(muEff, f)+ fvm::Sp(SpCoeff,f)- ScCoeff
);
solve(
fEqn);
rho=scalar(1)/((f/rho2)+((1-f)/rho1));rhoPhi=phi*fvc::interpolate(rho);
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Venturi Type Section
Ventury-type section1
σ = 2.4,
Vref = 7.2m/s
MyRASinterPhaseChangeFoam
MyFCM
[1] Coutier-Delgosha, O., et. al, 2003, Evaluation of the Turbulence Model Influence on the Numerical Simulations of
Unsteady Cavitation, J. Fluids Eng., 125, pp. 38-45
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
MyRASinterPhaseChangeFoamFull Cavitation Model
Naca 0015
Contours of the Vapour Volume Fraction
MyRASinterPhaseChangeFoam MyFCM
Vin = 6m/sα = 8o
Re = 3 · 105
σ = 1.2
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Conclusions
NUMAP-FOAM 2009 Zagreb, 14 September
IntroductionPropeller in Uniform Flow
Cavitation ModellingConclusions
Conclusions
What I have achieved:Procedure for the prediction of the flow around a marine propeller working in
uniform flow and non cavitating conditions
What I am planning to do:Investigate the influence of the turbulent model on the prediction of theperformances of the propeller working in uniform flow
Validate the cavitating flow solver MyRASinterPhaseChangeFoam
Improve the cavitating flow solver MyFCM
Develop a procedure for the prediction of the flow around a marine propeller
working in uniform flow and cavitating conditions
NUMAP-FOAM 2009 Zagreb, 14 September