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 Abhishek Thakur November 11, 2011 12:44

Generated Rotor(G-rotor) type oil pump simulation

Hi everybody,

I am new to Solidworks flow simulation. I have created a CAD model of pump with inner rotor & outer rotor housing and cover plate. I need to do the flow analysis of this assembly. I have tried using global rotating method but the problem is that we can assign RPM to assembly and fix non moving walls as stator. But here outer rotor gets rotation from inner rotor only i.e. if gear ratio b/w inner to outer is 9/10 and i give 1000 rpm to inner, outer should rotate by 900. What should I do. Should I use local rotation method and assign wall rotation of 1000 rpm to each wall of inner and 900 rpm to each wall of outer rotor and keep other walls stator?? the inner rotor moves eccentric to outer. How to do analysis with that feature. Also please tell if there is any need to include clearances between housing and rotors like axial clearances, end float into flow simulation analysis. Any suggestion will be very helpful to me. Thanks in advance

 Boris_M November 17, 2011 10:56

If you have an assembly with 2 seperate rotating parts, by seperate I mean not on the same axis or with different speeds or directions, you should use local rotation and define a ratating region where each rotor can have his own RPM and direction independent from the other rotor.
Another thing you should understand is that the wall definition as stator or rotor is only defining the boundary layer, if the wall is moving the flow will receive a velocity in it's boundary layer that can strech into the core flow due to shear stress in the fluid. This should not be applied to the fan blades as not the geometry it selfe is rotating then but the surface induces a velocity in the flow as described before.
The stator wall is necessary if for example you have a ducted fan and you define the rotating region around the fan into the duct which is a stator than you can define the walls of the fan as stator so the wall is not seen as moving but steady and therefore the relative velocity is zero at the wall.