Wind turbine noise from an industrial point of view

This paper deals with the description of the activities in which the wind turbine industry is taking part to reduce the noise emission of future wind turbines. The noise produced by wind turbines could risk the development of this technology in populated areas and it has become one of the most important environmental impacts of wind energy. The numerical study of the wind turbine behaviour is one of the most challenging problems a designer could face. The turbulent nature of the incoming flow with sudden changes of direction and velocity, the presence of the terrestrial boundary layer, the wind turbine elastic deformation and the moving geometry makes the problem difficult to solve. In this context the only reasonable alternative for industry is to find semi-empirical methods that could be applied to reduce noise with the time constraints imposed by the wind energy market. The beginning of this paper introduces the most relevant noise sources in the wind turbine and their theoretical treatment, then the description of the strategies that are used to reduce noise levels are discussed, and finally the current research projects where the industry is participating with the objective of noise reduction are presented.