Hello,
I could not find out to what axis the resulting pitching moments at the different blade stations are refering to?
Is it the pitch axis? Or the 25% chord line? Or something else?
Thanks a lot
Holger
Dear Holger,
The blade-root pitching moments in FAST are calculated about the blade-pitch axis.
Best regards,
Hi Jason,
thank you. But whats about the stations along the blade, not at the blade root? Is it there also the pitch axis? Then this axis lies outside the blade, if the blade is prebended for example.
Best regards,
Holger
Dear Holger,
For the local blade-pitch moments, FAST calculates the loads about an axis that deflects with the blade and that coincides with the pitch axis when the blade is undeflected.
FAST cannot currently handle blades with built-in curvature or sweep, such as blades with prebend. That said, NREL is making good progress on the development of our new BeamDyn module for FAST v8. This module will greatly enhance FAST’s ability to model blade structural dynamics. BeamDyn is based on geometrically exact beam theory (GEBT) and implemented using spectral finite elements. The model includes full geometric nonlinearity; bending torsion, shear, and extensional DOFs; anisotropic material couplings (full 6x6 mass and stiffness matrices); sectional offsets; and initially curved/swept blades. We are working through an extensive verification effort, will make it more user-friendly, will couple it to FAST, document it, and release it. Our goal is for the first public release in June, 2014.
Best regards,