Learning Forum

[PipMin]

Dear all, 

I am currently working on the simulation of the flow over and around a small scale horizontal axis wind turbine. I designed the rotor on SolidWorks and I imported in DesignModeler in order to create the fluid domain. I followed the standard method and drew two fluid domains, one small cylinder around the turbine that is the rotating fluid domain and one large fluid domain. I created to booleans:  one that deals with the large domain and the rotating domain (for which I preserved the target body which is the rotating domain) and the other boolean that deals with the rotating fluid domain and the rotor for which I didn't preserve the rotor. In the end, I got two bodies.

The mesh seems pretty good and there is no problem with it (around 2 million elements). In ran only steady simulations with the k-w SST model of turbulence.

In terms of cell zone conditions, I put the rotating fluid domain as "frame motion" with a rotation speed of 30.6 rad/s and oriented it in the direction perpendicular to the rotor. For boundary conditions, I put: a velocity of 3.15 m/s at the inlet, a pressure inlet all around the large domain, pressure outlet at the outlet and the rotor is set as "stationary wall".

For reference values, I selected: area = rotor area, velocity = inlet velocity, length = diameter of the rotor, pressure = 0 and the rest as default values.

I reached a convergence of 10^-3 for all equations but I couldn't get better. 

I extracted the torque on the rotor in the direction of rotation and I got a torque which is 10 times less than the one that I should have based on the BEM theory and experiment results. 

I don't understand why the results are so far from what I should get. Do you have any ideas? Is this set-up relevant? 

If someone has already done a similar simulation, could he please share his fluent set-up?

Thank you very much for your help.

Fillipo

[VSOlawoore]

Hi, Fillipo ... were you able to solve this problem?n

[Rob]

Most likely the issue is that frame motion just tells the rotor it's moving, mesh motion is the one that will actually move the rotor. Rotor is then set as moving wall relative to neighbouring cell zone, taking care to set the axis. n