The purpose of this study is to investigate numerically the blade aerodynamic noise and to predict the noise map in offshore wind-farm. For the analysis of the flow field around wind turbine blade, the unsteady vortex lattice method is applied, the panel code X-FOIL is used for boundary layer properties of airfoil. The acoustic analogy and semi-empirical method is used for modeling of various aerodynamic noise sources and the ENPRO as a propagation model is applied for the simulation of noise map. The used methodology for noise prediction could be applied efficiently to blade design stage for development of low noise blade and to noise assessment of wind-farm.
Wind power is one of most cost effective, reliable renewable energy source. A lot of country have installed the wind turbine in onshore/offshore and investigated the wind power for more efficiency and reliability. However, there have been many adverse effects such as site pollution, TV interference and noise (unwanted sound) pollution when turbine is installed and operated. In order to resolve these environment problems and to increase the efficiency of wind power, the wind-farm has been built up in offshore area or far region from residence area. Especially, it is predicted that offshore wind-farm would be promoted further due to the better wind properties suitable to high megawatt wind turbine. Among the environmental problems, the noise problem is still the major obstacle in the tremendous development of wind turbine over the last years. Noise gives an adverse effect to marine animal as well as human being. Fig. 1 shows the typical pile-fixed type offshore wind turbine and noise propagation mechanism from wind turbine to observer in air and underwater. When noise propagates through phase discontinuity surface, there is a transmission loss and refraction due to density difference.