Three innovative 20m-long wind turbine blades are undergoing testing in the USA as part of a project backed by the German government.

Designed by the Fraunhofer IWES research centre and built by the German Aerospace Centre, the blades have been installed at the US Department of Energy’s National Wind Technology Center in Boulder (Colorado) as part of the SmartBlade2 project.

The aim is to clarify how well the blades — designed with bend-twist coupling — can dampen peak loads during strongly variable wind speeds.

Fraunhofer IWES said the results will serve as a basis for the further development of smart rotor blades that can adapt to varying wind conditions by themselves.

Specially developed measurement systems have been integrated into the blades to assess their structural and aerodynamic behaviour.

Christian Kress, Fraunhofer IWES (www.iwes.fraunhofer.de) project manager, said: “We are using several measurement systems that will allow us to monitor the entire length of the blades in order to capture the deformations, accelerations and loads they are subjected to.

“In addition, the air flow around the rotor blades will be recorded at the surface, using an aerodynamic measurement system.”