A few things to try:
- In CAD file you need to increase the MRF cylinder radius so that it fully encloses your blades, but just a little bigger than the blades
. - While you are in the CAD file, simplify your geometry a little by removing the ‘axle holes’ that the blade spins on. They add unnecessary ‘confusion’
- I agree with @jousefm, but if you insist on using that size BMB, then try changing all BMB faces to Custom>Inlet-Outlets with ZeroGradient pressure and set the air velocity of the simulation run inside that Custom BC (I would do both, increase BMB size and use the described BC). Increasing BMB size only adds a few cells as they are generally Level 0 cells …