In theory, with a yawed rigid turbine (or skewed inflow), I would expect no yaw moment at the rotor (LSSTipMzs = 0), because the angle of attack should change at positions 0° and 180° only and not from side to side.
Instead I get quite high yaw moments in the partial load range. I found out that the maximal blade bending moment occurs at 60°, not at 0° as anticipated.
My simulation parameters:
Wind: HH-Windfile, const. partial load wind speed and horizontal skew only.
FAST fst: All DOF false, except for GenDOF and CompAero, 0 tilt, 0 precone, symmetric rotor, const pitch
AeroDyn ipt: StallMod steady, UseCm no, InfModel EQUIL, IndModel SWIRL (or WAKE), Prandtl tip and hub losses, no tower effects
I read about sources for yaw loads in nrel.gov/docs/legosti/old/4822.pdf and tried to exclude all sources for yaw moments with the choice of parameters but I still get these loads.
I hope the code is correct, but what am I disregarding that causes yaw loads?
Thanks for any ideas!