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-   -   Turbomachinery and FLUENT (http://www.cfd-online.com/Forums/main/709-turbomachinery-fluent.html)

chris April 9, 1999 02:02

Turbomachinery and FLUENT
 
Hy, I want to design centrifugal pumps with FLUENT. My questions:

1. what do you think about the tools MRF and mixing plane ? do they provide good results and how is the convergence ? 2. sliding meshes: how many hours needs this unsteady 3D-calculation until you get usefull results? how much elements ? what type of hardware ? Is the sliding mesh tool really usefull in the "daily use" or is it more an "academic tool" for science and universities ?

Joern Beilke April 9, 1999 05:23

Re: Turbomachinery and FLUENT
 
For some cases MFR gives good results. Sometimes they even don't show the right direction. Then you have to use sliding mesh. Also if you are interested in transient phenomena like acoustics ... you have to use sliding mesh.

The computing time jumps from some hours (mfr) up to several weeks for sliding mesh :( Just expect to run 3 revolutions to get a periodic solution. To check this you should compute the integral values of the mass flux at the inlet and outlet at every time step and monitor them.

There are some articles about these things on my home page (www.beilke-cfd.de)

Alberto Tamm April 20, 1999 14:56

Re: Turbomachinery and FLUENT
 
Hello Chris,

First, sorry for my bad english.

The MRF tools give you good solutions when the interaction between rotor-stator is weak (now is the question what is weak?). It depends from the turbomachinery you are modelling. If you are modelling a pump with a volute, you will probably have problems in the tounge (born), but the global results will be reazonable.

Now Im modelling a nq12 pump using MRF model (without lateral space (ohne radseitenraum), K-E, 3D. Operating under turbine and pump condition (betrieb).Structured mesh. 800.000 cells. aprox. 12 hours for converge.

In the nominal operating condition the results are good but with lower flow the Total presure are bigger in the static-rotor interface than in the inlet boundary face. Which is not good. (Turbinen-betrieb)

Im very interesting in analize my results. If you have more experience in this topic, please write me an e.mail.


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