Elastic Edges for Wind Turbine Blades
The life of wind turbine blades can be significantly enhanced by modifying their shape. There is a lot of load on the large wind turbines when the blades rotate and by providing a movable trailing edge to these blades the load can be tremendously reduced. It is similar to the flaps used in the aeronautical industry. The flaps in aircrafts regulate the lift during take-offs and landings. Risø National Laboratory for Sustainable Energy is using an elastic material to make trailing edges of wind turbine blades.
Helge Aagaard Madsen, who is a research specialist on the project, explains, “Providing the blade with a movable trailing edge it is possible to control the load on the blade and extend the life time of the wind turbine components. This is similar to the technique used on aircrafts, where flaps regulate the lift during the most critical times such as at take-off and landing.”
“If the results confirm our estimated performance, we will test the rubber trailing edge on a full-scale wind turbine within a few years,” he said.
The big difference is that in aircrafts the movable flaps don’t bend or change shape according to the pressure or load, but this new technique provides a continuous surface of the profile on the wind turbine blade even when the trailing edge moves. The reason for this is that the trailing edge is constructed in elastic material (a pultruded fiber glass reinforced composite) and constitutes an integrated part of the main blade.
The research, supported by the Ministry of Science, Technology and Innovation and by the local Region Zealand, has led to the manufacturing of a trailing edge of rubber with built-in cavities that are fibre-reinforced (pultrusion). The cavities, combined with the directional fibre reinforcement, provide the desired movement of the trailing edge, when the cavities are being put under pressure by air or water and this saves them from wear-and-tear and other incidental damages. This new technique is soon going to be tested in a wind tunnel.