Blades could have smart future

German researchers have examined new concepts for so-called ‘smart’ rotor blades that can adapt to the wind.

The three-year €12m Smart Blades project was funded by the German Federal Ministry for Economic Affairs and Energy.

It has examined blades that are able to adapt their geometry to suit the local wind conditions using active and passive technologies.

The project was a joint effort between Research Alliance Wind Energy (FVWE) the German Aerospace Center (DLR), Fraunhofer IWES and ForWind, the Center for Wind Energy Research of the Universities of Oldenburg, Hanover and Bremen.

“The findings of this project offer turbine developers and operators new information and tools allowing them to launch more effective, more cost-efficient and more reliable system designs on the market,” the researchers said.

They added that when a rotor blade is subject to high wind it turns in such a way that it offers the wind a smaller contact surface, known as bending-torsion coupling.

The bending is initiated by the force of the wind alone and is described as a ‘passive’ mechanism.

The research focused on two approaches that produce this effect. On the one hand, a crescent-shaped geometry was examined and, on the other, a particular structure was employed for the material composition of the rotor blade.

Fraunhofer IWES smart blades technology coordinator Alper Sevinc said: “The advantages of the mechanisms are that the blades can be built with a less robust design and are therefore lighter.

“Both processes have the potential to improve the energy utilization of wind power systems.”

The researchers now hope to be able to investigate the mechanisms tested in the simulation on demonstration rotor blades they have already designed in a future project.

The researchers also looked at active mechanisms that adapt the trailing edges of a rotor blade and which system operators can use to control the aerodynamic loads on a rotor blade.

They said the concept was inspired by the aviation industry and is comparable to the flaps on the wings of aircraft.

The researchers also considered whether a flexible leading edge flap on a rotor blade can improve the efficiency of wind turbines subject to heavily fluctuating, turbulent wind conditions.

The new approaches were test for cost-efficiency with a state-of-the-art 80-metre-long rotor blade in simulations.

The next step would be for the researchers to be able to test their results on full-scale rotor blades.

Image: some of the smart blade concepts (Fraunhofer IWES)