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-   -   Propellar CFD Analysis Questions (http://www.cfd-online.com/Forums/floefd-floworks-flotherm/27214-propellar-cfd-analysis-questions.html)

Craig December 18, 2008 10:37

Propellar CFD Analysis Questions
 
I am attempting to determine the efficiency and forward velocity of a propellar (in water) at a specific RPM rotating around the z axes. For this, I need the following parameters (the associated goals in parantheses):

Thrust force (Z force on prop - surface goal), Torque (torque in the z on prop - surface goal), Rotational Velocity (defined as global rotaton in rad/s), Forward Velocity (velocity in the z - global goal)

I also want to explore the possibility of cavitation so I have set the model up with the above parameters and the following:

Check "cavitation" checkbox Increase turbulence to 1% (typical of most flow tanks) Global mesh refinement of 4 Local mesh (on prop) refinement of 6 Density global goal also added (for cavitation) Velocity Z RRF Global Goal also added Efficieny equation goal

I have set the intial conditions at 0 m/s flow in all directions and seet my calculation control options to finish once all goals are achieved. My travels is still on auto at 0.5.

So - the problem - after 3000 iterations I have still not hit a steady state. This seems odd to me compared to other studies I have done. Is this trypical, and I must be patient, or is something in my set up wrong???

jeremy February 25, 2009 04:35

Re: Propellar CFD Analysis Questions
 
You can send me your model with your FLOEFD definition so I can check and confrm your question .


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