Pitch angle and tower top response

Wind & Water Structural Analysis
1

Hello,

I am running upwind wind turbine model.
No platform - tower is fixed to the ground.
yaw angle is= 0 (both initial and final),
YawDOF = False.
Turbine is parked.
Analysis was performed for two cases
case 1 : BlPitch ( 1,2,3) = 0 means blade chord is parallel to horizontal wind direction. i.e. leading edge faces the wind.
case 2 : BlPitch ( 1,2,3) = 90 means blade chord is perpendicular to horizontal wind direction , i.e. flat side of blade faces the wind

It is expected to get higher value for tower top response for BlPitch =90 when compared with BlPitch = 0. I get exactly opposite. Is there any specific damping routine getting called.

I am running simulation for 50 m/s mean wind speed at hub height of 80 m. ( I have scaled down the blade model from NREL 5MW turbine to a specification of smaller blade model.)

Any input/suggestion would prove of great help.

Regards
Atul.Patil
Student ( Florida State University, Tallahassee)

2

Dear Atul,

A blade pitch angle of 0 degrees corresponds to a case where the flat side of the blade faces the wind when not spinning and zero yaw error. A blade pitch angle of 90 degrees corresponds to a case where the leading edge of the blade faces the wind when not spinning and zero yaw error. The way you state the chord being “parallel” and “perpendicular” to the wind is swapped in your post.

I agree that a rotor parked with 0 degree pitch should be much more loaded than a rotor parked with 90 degree pitch. If you are not seeing this, I suspect you’ve set something up wrong in your input files.

Best regards,