An experimental system to acquire aeroacoustic properties on wind turbine blades

Wind turbine noise is a key issue preventing the successful exploitation of the full potential of wind energy throughout the world, especially in urban areas. To better assess and predict wind turbine noise, several aeroacoustic simulations and models have been developed over the past. Many semi-empirical models for noise emission and propagation rely on aeroacoustic properties at the blade level, including the pressure gradient, the spectrum of the pressure fluctuations, the convection velocity and the coherence lengths. Field measurements of these local quantities on operating wind turbines are valuable to improve the accuracy of the models. In the Aerosense project, a cost-effective smart measurement system is being developed that is thin, easy to install without damaging the blade, low power, self-sustaining and wirelessly transmitting. This measurement system uses MEMS sensors, which require some calibrations and corrections to obtain sufficiently accurate data. This paper describes the experimental system and its workflow, which has been developed within the Aerosense project to obtain sufficiently accurate measurements for semi-empirical noise emission and propagation models. The experimental system and its workflow are then validated in an anechoic wind tunnel on a NACA63-418 airfoil. The results show that this experimental system is able to acquire relevant aeroacoustic properties on operating wind turbines.