Concept and realization of a lightweight flexible trailing edge demonstrator for wind energy turbines

Abstract

Upon decreasing reserves of fossil energy sources and an expected increase of the global energy demand in future, regenerative energy sources are fundamental to guarantee a sufficient availability. Especially wind energy is investigated in this topic. To enlarge the power output, the rotor diameters have to be increased. A drawback for further increase arises from the square cube law, which decreases the structural safety margin. Therefore, load alleviation techniques such as moving trailing edges are investigated. One central challenge for wind energy turbines is to avoid maintenance effort as much as possible, why classical flap designs with gaps and discrete hinges cannot be used. To overcome this limitation, a concept for a flexible trailing edge is presented, where the whole trailing edge is deformed to achieve the required aerodynamic shape. First several possible concepts are discussed, where one concept is chosen to be investigated further. Finite-Element models in combination with an airfoil aerodynamic model are used to simulate the moving structure in terms of deflection and its reaction to aerodynamic forces. Based on these calculations, a concept demonstrator is designed, built and measured, which is compared to the simulated results. Finally, the developed models are used to design a 2 m wingspan and 1 m chord trailing edge demonstrator, which will be used to investigate the concept in a relevant environment on a rotating test.