Assessment of Surface-Based Aeroacoustic Noise From Blades of a Vertical-Axis Wind Turbine

Surface-based sources of aerodynamically-generated noise for the 17-m troposkien shape vertical-axis wind turbine are predicted using Farassat’s Formulation 1A of the Ffowcs Williams-Hawkings equation. By discretizing the three-dimensional turbine blades over the height of the turbine into constant-radius sections, the blades were aerodynamically modeled in two-dimensions in the horizontal plane by an unsteady panel method to obtain results for surface pressures and velocities. The acoustic pressure generated by the blades throughout their rotations was determined by the combination of loading and thickness noise sources on the surface of the blade sections in the time-domain. The simulation results were compared to experimental results for the acoustic pressure power spectral density. The sound pressure level around the turbine was found to have a slight dipole radiation pattern, caused primarily by the loading acoustic pressure on the blades.