Low-Noise Technologies for Wind Turbine Blades

The BMWi-funded wind energy project BELARWEA aims at the development and validation of improved methods to support the design of both efficient and low-noise wind turbine rotors. Aeroacoustically driven 2D profile design, 3D winglet design and 2D/3D CFD and CAA analysis are supplemented by the transfer of passive noise reduction technologies from aerospace applications to wind turbine blades. Based on a down-scaled version of the open source NREL-5-MW reference rotor, a noise reduction of at least 3 dB at a given rotor performance is targeted by a dedicated 3D redesign of the outer 20% of the rotor radius. Experimental demonstration and tool validation shall be provided in systematic validation steps, i.e. • at 2D blade sections in the AWB acoustic wind-tunnel of DLR and • at 3D blade tips in the larger acoustic facility DNW-NWB, operated by the German-Dutch Wind-Tunnels Foundation. The presentation provides in its first part an overall project overview. In its second part results from the first set of AWB measurements are summarized, yielding a detailed matrix of the relevant system parameters (i.e. aerodynamic performance vs. noise). Aeroacoustic predictions are compared with the experimental results and transposed to full scale conditions. In addition, the noise reduction potential of selected trailing-edge add-ons is evaluated at varying test velocities, angles of attack and boundary-layer transition regions