Constrained Aerodynamic & Aeroacoustic Design of Wind-Rotor Airfoils
Th. Lutz, A. Herrig, W. Würz, K. Braun and E. Krämer
Wind Turbine Noise: Perspectives for Flow Control, Berlin, October 17-18, 2005
The EU-funded research project SIROCCO aims on the reduction of the blade trailing-edge noise which represents the dominant noise source of modern wind turbines. This objective is followed by the design of new silent airfoils for the outer part of the blade. The present paper describes the staggered design procedure applied which involves parametric investigations, constrained numerical optimizations and a manual fine-tuning using a mixed-inverse design procedure. To enable a consistent noise prediction the aerodynamic calculation procedure had to be extended in order to better account for boundary-layer history and anisotropy effects and to improve the prediction of the relevant turbulence length scale. The enhanced method was validated and applied in the design of two airfoils which were wind-tunnel tested and showed the predicted acoustic gain and the intended aerodynamic performance.