Prediction and reduction of wind turbine noise - An overview of research activities in Europe

Abstract

The paper tackles the problem of aerodynamic noise from wind turbines. It concentrates on the specific noise sources which are relevant for a large, modem wind turbine in the 1 MW range. This is mainly trailing-edge noise which originates from the interaction of the turbulent boundary layer around the blade with the trailing edge. Additional noise sources are blade tip noise and inflow-turbulence noise while low-frequency noise is considered to be less relevant. The physical mechanisms of the noise generation are explained and prediction models for the single sources are described. These models are believed to be sensitive enough to capture the effect of airfoil geometry correctly. Therefore, they might be used to consider aerodynamic noise already during the design process, i.e. to design less noisy wind turbines. A further topic is the reduction of aerodynamic noise, mainly the serrated trailing edge which is the most promising concept to reduce trailing-edge noise and consequently the total noise of a wind turbine. In the last part of the paper a new approach to the prediction of aerodynamic noise in general is presented. Here some relevant concepts of aeroacoustic theory are explained.