[riesotto]

Hi,

For my Masterthesis I want to simulate the flow in a turbocharger. The Mach-Number of the flow is higher than 0.3, so I have to use a compressible solver (but not supersonic). I've done some simulations with MRFSimpleFoam (results not to bad at all), but this solver is for incompressible fluids. There is a solver called rhoPorousMRFSimpleFoam. Is it possible to simulate my problem with this solver, because I don't have a porous area inside???? My first tests with this solver was a flop, no chance to get a convergent case with my turbo. Some ideas??

please help

kind regards
Florian

[riesotto]

Hi all,

now I have some results, but with rhoPorousMRFLTPimpleFoam and only laminar. With kEpsilon-Modell it doesn't work (poor mesh quality, I don't know). Is it possible to run the case first laminar and then switch to turbulent??? Do I have to use the mapFields utility or is it possible to switch the RASModel in the RASProperties after some iterations?? What is the silver bullet to do this?

If somebody has experience in this please let me know.

kind regards
Florian

[bastil]

Florian,

some hints:
1. rhoPorousMRFSimpleFoam can be used without a porosity by simply defining none in the porousZones file.
2. Getting compressible OpenFOAM-Solvers to run can be very hard from of my experience.
3. You can simply do a restart on the latest time-folder of your laminar case to restart wih turbulence turned on.

[riesotto]

Hi Bastil,

thx for your reply.
I solved the problem first laminar and then turned on turbulence (like you said). Now it works. I have now a convergent case and the results looks not so bad. Thank you for your advice.
I will do some further simulation and some measurments in the lab. Then I will find out how well the simulation works.

kind regards
Florian

[val46]

Hi Florian,

i'm very interested in what you did.
What kind of mesh do you have?

Would be nice to keep us up-to-date.


Regards,
Toni

[riesotto]

Hi Toni,

I use a hybrid mesh (from Gambit). I convert the mesh into OpenFOAM (fluentMeshtoFoam). At the moment it is a hex mesh + tet-mesh. But I will give it a shot with a polydualmesh. At the moment I'm looking for proper boundary conditions for my simulation.
I keep you updated.

kind regards,
Florian

[riesotto]

Hi Toni,
hi all,

at the moment I solve some cases with compressible and turbulent flow regime in the turbocharger. For this cases I have done some measurements in the lab for validation.
I measured:
- the velocity at the inlet of the turbocharger
- the RPM of the rotor
- the shaft-power of the rotor for different RPM (3500 rad/s, 6000 rad/s, 9000 rad/s ...)

For the validation I set the inlet velocity with the corresponding RPM of the rotor. Then I simulate the shaft-power of the rotor and compare it with the measured power.

Until now, the simulated shaftpower is significant lower than the measured power. But I have to include the efficency of the gear, the engine, the batteries... for the calculations. Pherhaps the results will be better.

Regards,
Florian

[jyothishkumar]

hi florian,

I am trying to run turbocharger compressor flow in openfoam. Can I use the rhoporousMRFSimpleFoam solver for that. Can you please tell me how to separate the rotating faces from the nonrotating one. Please help me in this regards.

Thanks

Jyothish

[jyothishkumar]

hi florian,

I am trying to run turbocharger compressor flow in openfoam. Can I use the rhoporousMRFSimpleFoam solver for that. Can you please tell me how to separate the rotating faces from the nonrotating one. Please help me in this regards.

Thanks

Jyothish