studies of the ercoftac centrifugal pump with openfoam

Studies of the ERCOFTAC Centrifugal Pumpwith OpenFOAM

Shasha Xie

June 7, 2010

Title page - - Shasha Xie June 7, 2010 1/40

Outline

Outline

I Purpose and goal

I Method and approach

I Geometry

I Boundary condition

I Results

I Conclusions

Outline - - Shasha Xie June 7, 2010 2/40

Purpose and goal

I To investigate the rotor-stator interactions in the ERCOFTACCentrifugal Pump using OpenFOAM 1.5-dev.

I Carry out the unsteady simulation for both 2D and 3D modeling.

I Compare the results of the numerical solution with the experimentaldata.

Purpose and goal - - Shasha Xie June 7, 2010 3/40

Method and Approach

I MethodI 2D and 3D mesh were generated using ICEM-Hexa.I Incompressible Reynolds-Averaged Navier-Stokes equations are solved.I The standard k-ε turbulence model is used.I Generalized Grid Interface (GGI) is used:

I for the steady-state simulations.I for the unsteady simulations.

I ApproachI 2D steady-state simulationI 2D unsteady simulationI 3D steady-state simulationI 3D unsteady simulation

Method and Approach - - Shasha Xie June 7, 2010 4/40

Geometry

I Geometry of the ERCOFTAC Centrifugal Pump.

I The positions where the simulated results are plotted.

Figure: Geometry and positions for plotting the simulated results.

Geometry - - Shasha Xie June 7, 2010 5/40

Geometry

I Geometry of 2D (left) and 3D (right) model.

Geometry - - Shasha Xie June 7, 2010 6/40

Boundary conditions

I Boundary conditions.

Calculated data for the 2D cases for the 3D casesInlet Diameter D0=184 mm D0=200 mm

Z thickness Z=1 mm Z=40 mm

Flow rate Q=ϕU2πD2

24 =0.292 m3/s Q=0.292 m3/s

Inlet speed U0= QA0

= Q2πr0∗0.04=11.4 m/s U0=10.98 m/s

Rotating speed ω = 2000 rpm ω = 2000 rpm

Boundary conditions for the 2D cases for the 3D casesAt the inlet Vradial=U0 Vaxial=U0

µTµ =10 µT

µ =10

k=32U2

0 I 2=0.48735 m2/s2 (I=5%) k=0.4521 m2/s2

ε=Cµρk2

µT=

Cµρk2

µ(µT /µ)=Cµk2

ν(µT /µ)

At the outlet Average static pressure 0

Boundary conditions - - Shasha Xie June 7, 2010 7/40

2D steady-state simulation

2D steady-state simulation.

Results - 2D steady-state simulation - Shasha Xie June 7, 2010 8/40

Set-up for the 2D steady-state simulation

I Set-up for the case 2DSteady.

Schemes Convection schemes of U linearUpwind Gauss

Solvers p GAMGsmoother GaussSeideltolerance 1.0e-08relTol 0.05

U,k ,ε smoothSolversmoother GaussSeideltolerance 1.0e-07relTol 0.1


Results for the case 2DSteady

I Contours of the relative velocity magnitude (left) and static pressure(right) for the case 2DSteady.



I Distribution of the radial (top left), tangential (top right) velocitiesand static pressure coefficient (down) for the case 2DSteady.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

Wr/U

2

yi/Gi

experimental2DSteady

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

0 0.5 1 1.5 2

Wu/

U2

yi/Gi


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2

C~p

yi/Gi



2D unsteady simulation

2D unsteady simulation.

I Compare the convection scheme:2DEulerU0.5T, 2DEulerL0.5T

I Compare the time discretization scheme:2DBackL0.5T, 2DEulerL0.5T, 2DCN0.5L0.5T

I Compare the Crank-Nicholson off-centering coefficient:2DCN0.2L0.5T, 2DCN0.5L0.5T, 2DCN0.8L0.5T, 2DCN1.0L0.5T

I Compare the maximum Courant Number:2DCN0.5L0.5T, 2DCN0.5L1.0T, 2DCN0.5L2.0T, 2DCN0.5L4.0T

I Compare the transient solver:2DCN0.5L0.5T, 2DCN0.5L0.5S

Results - 2D unsteady simulation - Shasha Xie June 7, 2010 12/40

Stop time is set 0.3 s

I Pressure development of 2D unsteady simulation at Probe 1 (top left),Probe 2 (top right) and Probe 3 (down left) until fully developed.

-960

-940

-920

-900

-880

-860

-840

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 1

-200

-150

-100

-50

0

50

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 2

-40

-30

-20

-10

0

10

20

30

40

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 3


Compare the convection scheme

I Set-up for the case 2DEulerU0.5T and 2DEulerL0.5T.Case Convection scheme

2DEulerU0.5T upwind2DEulerL0.5T linear upwind

Time discretization scheme Euler

maxCo 0.5

Solver turbDyMFoam

Correctors nCorrectors 2nOuterCorrectors 1nNonOrthogonalCorrectors 1

endTime 0.3 s

Results - 2D unsteady simulation - Convection scheme Shasha Xie June 7, 2010 14/40


I Contours of the relative velocity magnitude for the case2DEulerU0.5T (left) and 2DEulerL0.5T (right).



I Distribution of the radial velocity for the case 2DEulerU0.5T and2DEulerL0.5T.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

wr/U

2

yi/Gi

t/Ti=0.126

experimental2DEulerU0.5T2DEulerL0.5T


Compare the time discretization scheme

I Set-up for the case 2DBackL0.5T, 2DEulerL0.5T and 2DCN0.5L0.5T.Case Time discretization scheme Computing time

2DBackL0.5T backward 22.0 hours

2DEulerL0.5T Euler 22.7 hours

2DCN0.5L0.5T Crank-Nicholson 0.5 23.9 hours

Convection scheme linearUpwind

maxCo 0.5

Solver turbDyMFoam


endTime 0.3 s

Results - 2D unsteady simulation - Time discretization scheme Shasha Xie June 7, 2010 17/40


I Distribution of radial velocity for the case 2DBackL0.5T,2DEulerL0.5T and 2DCN0.5L0.5T.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

wr/U

2

yi/Gi

t/Ti=0.126

experimental2DBackL0.5T2DEulerL0.5T

2DCN0.5L0.5T



I Contours of the relative velocity magnitude (left) and static pressure(right) for the case 2DBackL0.5T.



I Contours of the static pressure coefficient for the case 2DBackL0.5T(left) and experimental results (right).


Compare the Crank-Nicholson off-centering coefficient

I Set-up for the case 2DCN0.2L0.5T, 2DCN0.5L0.5T, 2DCN0.8L0.5Tand 2DCN1.0L0.5T.

Case Time discretization scheme

2DCN0.2L0.5T Crank-Nicholson 0.22DCN0.5L0.5T Crank-Nicholson 0.52DCN0.8L0.5T Crank-Nicholson 0.82DCN1.0L0.5T Crank-Nicholson 1.0


maxCo 0.5

Solver turbDyMFoam


endTime 0.3 s

Results - 2D unsteady simulation - Crank-Nicholson coefficient Shasha Xie June 7, 2010 21/40

Compare the Crank-Nicholson off-centering coefficient

I Pressure fluctuation at Probe 1 for the case 2DCN0.2L0.5T (top left),2DCN0.5L0.5T (top right) and 2DCN0.8L0.5T (down left).

-940

-930

-920

-910

-900

-890

0.29 0.291 0.292 0.293 0.294 0.295

p/rh

o

Time [s]

2DCN0.2L0.5T

-940

-930

-920

-910

-900

-890

0.29 0.291 0.292 0.293 0.294 0.295

p/rh

o

Time [s]

2DCN0.5L0.5T

-940

-930

-920

-910

-900

-890

0.29 0.291 0.292 0.293 0.294 0.295

p/rh

o

Time [s]

2DCN0.8L0.5T

Results - 2D unsteady simulation - Crank-Nicholson coefficient Shasha Xie June 7, 2010 22/40

Compare the maximum Courant Number

I Set-up for the case 2DCN0.5L0.5T, 2DCN0.5L1.0T, 2DCN0.5L2.0Tand 2DCN0.5L4.0T.

Case maxCo Time step Computing time

2DCN0.5L0.5T 0.5 0.80 ∗ 10−5s 23.9 hours

2DCN0.5L1.0T 1.0 1.58 ∗ 10−5s 11.7 hours

2DCN0.5L2.0T 2.0 3.13 ∗ 10−5s 6.4 hours

2DCN0.5L4.0T 4.0 6.20 ∗ 10−5s 3.5 hours

Time discretization scheme Crank-Nicholson 0.5


Solver turbDyMFoam


endTime 0.3 s

Results - 2D unsteady simulation - Maximum Courant Number Shasha Xie June 7, 2010 23/40

Compare the maximum Courant Number

I Distribution of the radial velocity for the case 2DCN0.5L0.5T,2DCN0.5L1.0T, 2DCN0.5L2.0T and 2DCN0.5L4.0T.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

wr/U

2

yi/Gi

t/Ti=0.126

experimental2DCN0.5L0.5T2DCN0.5L1.0T2DCN0.5L2.0T2DCN0.5L4.0T

Results - 2D unsteady simulation - Maximum Courant Number Shasha Xie June 7, 2010 24/40

Compare the transient solver

I Set-up for the case 2DCN0.5L0.5T and 2DCN0.5L0.5S.

Case Solver nCorrectors nOuter-Correctors

nNon-Orthogonal-Correctors

2DCN0.5L0.5T turbDyMFoam 2 1 1

2DCN0.5L0.5S transientSim-pleDyMFoam

0 1 0

Time discretization scheme Crank-Nicholson 0.5


maxCo 0.5

endTime 0.3 s

Results - 2D unsteady simulation - Transient Solver Shasha Xie June 7, 2010 25/40


I Contours of the relative velocity magnitude for the case2DCN0.5L0.5T (left) and 2DCN0.5L0.5S (right).



I Distribution of the radial velocity for the case 2DCN0.5L0.5T and2DCN0.5L0.5S.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

Wr/U

2

yi/Gi

t/Ti=0.126

experimental2DCN0.5L0.5T2DCN0.5L0.5S


3D steady-state simulation

3D steady-state simulation.


Set-up for the 3D steady-state simulation

I Set-up for the case 3DSteady.

Schemes Convection schemes of U linearUpwind Gauss

Solvers p,U,k ,ε GAMGsmoother GaussSeideltolerance 1.0e-08relTol 0.05



I Contours of the relative velocity magnitude (left) and static pressure(right) at the midspan position for the case 3DSteady.



I Distribution of the radial (top left), tangential (top right) velocitiesand static pressure coefficient (down) at the midspan position for thecase 3DSteady.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

Wr/U

2

yi/Gi


-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

0 0.5 1 1.5 2

Wu/

U2

yi/Gi


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2

C~p

yi/Gi



3D unsteady simulation

3D unsteady simulation.


Set-up for the 3D unsteady simulation

I Set-up for the case 3DBackL0.5S.

Case 3DBackL0.5S

Time discretization scheme backward


maxCo 0.5

Stop time 0.3 s

Solver transientSimpleDyMFoam


Computing time 113.5 hours < 5 days


Stop time is set 0.3 s

I Pressure development at Probe 1 (top left), Probe 2 (top right) andProbe 3 (down) for the 3D unsteady simulation until fully developed.

-1000

-950

-900

-850

-800

-750

-700

-650

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 1

-200

-150

-100

-50

0

50

100

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 2

-40

-30

-20

-10

0

10

20

30

40

0 0.05 0.1 0.15 0.2 0.25 0.3

p/rh

o

Time [s]

Probe 3


Results for the case 3DBackL0.5S

I Contours of the relative velocity magnitude (left) and static pressure(right) at the midspan position for the case 3DBackL0.5S.



I Distribution of the radial (top left), tangential (top right) velocitiesand static pressure coefficient (down left) at the midspan position forthe case 3DBackL0.5S.

0

0.05

0.1

0.15

0.2

0.25

0.3

0 0.5 1 1.5 2

Wr/U

2

yi/Gi

t/Ti=0.126

experimental3DBackL0.5S

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

0 0.5 1 1.5 2

Wu/

U2

yi/Gi

t/Ti=0.126


0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2

C~p

yi/Gi

t/Ti=0.0




I Contours of the radial (left) and tangential (right) velocities fordifferent span distances for the case 3DBackL0.5S (top) andexperimental (down).


Conclusion

I All the computational cases show some similarities with theexperimental results.

I The unsteady simulations show better prediction of the wakes thanthe steady-state simulation.

I The first-order upwind convection scheme failed in capturing the wakeeffect of the flow unsteadiness.

I Balance between short computing time and damping on the choice ofmaximum Courant Number.

I The transientSimpleDyMFoam solver shows the possibility for the 3Dunsteady simulation but still needs more validations and more testings.

Conclusion - - Shasha Xie June 7, 2010 38/40

Acknowledgements

I would like to say my thanks to

I Division of Fluid Dynamics, Department of Applied Mechanics

I Supervisors Hakan Nilsson and Olivier Petit

Acknowledgements - - Shasha Xie June 7, 2010 39/40

Thanks!

Thank you for listening.Questions?

End - - Shasha Xie June 7, 2010 40/40

studies of the ercoftac centrifugal pump with openfoam

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