According to a research undertaken at Risø DTU National Laboratory for Sustainable Energy in Denmark, controlled rubber flaps could assist in making wind turbines produce less noise and a greater energy output. Lead by Helge Aagaard Madsen, the wind-tunnel tests have proven the flaps’ ability to help control loads on large wind-turbine blades. The researchers tested their flaps in an open-jet wind tunnel at skylight manufacturer Velux in Denmark.
The system is called CRTEF (Controllable Rubber Trailing Edge Flap). It is expected to have a control system that makes use of information from embedded sensors to direct the movement of the flaps. These sensors would be capable of detecting local wind conditions along the blade. Pitched blades in wind turbines reduce loads by 25 to 30 percent in comparison to the ones without them, but adding flaps can bring down the loads by 40 percent or more.