This paper studies the effects of backwards sweep and coning angle on a 10 m blade for a 100 kW stall-controlled downwind 3-bladed horizontal axis wind turbine.
The purpose of this study is to determine whether the yaw moment of the nacelle would induce a restoring force when an error between the
nacelle orientation and the wind is introduced into the system.
This will help to evaluate the use of different passive control systems for potential use in a free yaw system. It was found that a backwards swept blade combined with a 10 degree coning angle are most effective in increasing the yaw restoring moment, and that over almost all the wind speeds this moment is acting in the correct direction, to turn the nacelle back into the wind.
Reductions of the restoring yaw moment were discovered in the 12 to 15 m/ s range, and are suspected to be caused by the transition from
the pre- to post-stall models.
Article presented at EWEA Brussels, 14-17/03/2011