Teeter configuration

Hello,

I am studying 2 blades teetering WTG with FAST, and I would like to get a clarification regarding this matter :

  1. In .fst files, one can edit the parameters of the teeter : I would like to know in which coordinate system shall the stiffness and the damping be put? In the (xa,ya,za) coordinate system of in the coordinate system attached to the teeter ie aligned with the axis of rotation of the hub

  2. Regarding the output given by Fast for teeter motion, velocity & acceleration, are the values given in the hub coordinate (xa,ya,za) or in the teeter coordinate?

Best Regards,
Mathieu GUYONNET

In my first question, one shall read

'1. In .fst files, one can edit the parameters of the teeter : I would like to know in which coordinate system shall the stiffness and the damping be put? In the (xa,ya,za) coordinate system or in the coordinate system attached to the teeter ie aligned with the axis of rotation of the teeter pin

Best Regards,
Mathieu Guyonnet

Dear Mathieu,

I’m not sure I understand what you mean when talk about stiffness, damping, and motion refering to different coordinate systems.

Regardless, in FAST, the teeter springs, dampers, and stops are all rotational elements defined for rotations about the teeter axis. The neutral (reference) position corresponds to a teeter angle of zero, which corresponds to a rotor whose blade axes are equal angles from the axis of rotation. The teeter displacement (angle), velocity, and acceleration are rotational motions of the hub relative to the shaft do solely to teeter motion. Reference Figure 14 from the FAST User’s Guide.

I hope that helps.

Best regards,

Hello,

Thank you very much for your clear answer, I got it.

Best Regards,
Mathieu Guyonnet,
Nass et Wind Industrie