Dear @Tongzhou.Zhang,
Just a few comments:
- You will get the first warning regarding “temporarily turning off UA” if either the angle of attack approaches
UACutOut(DEFUALT = +/-45 degrees) (the warning is triggered 5-deg before the cut-out) or the relative inflow velocity approaches 0 m/s (the warning is triggered at 1 m/s). - You haven’t said what initial conditions you are using, but you can see if improving the initial conditions eliminates the 2nd and 3rd warnings. We typically recommend initializing the rotor speed and the blade-pitch angles to their expected (mean) values conditioned on the mean hub-height wind speed; are you doing that here? You can further improve the initial conditions by setting the initial blade and tower deflections to their expected (mean) values conditioned on the mean hub-height wind speed. Does that eliminate the 2nd and 3rd warnings?
- I would expect large angles of attack at inboard stations and large variations in angle of attack at higher wind speeds (which likely have higher wind speed standard deviations than at lower mean wind speeds).
Best regards,