Wind turbine noise generation and propagation through large-eddy simulation and acoustic analogy: the case of the complete wind turbine

Abstract

Abstract Content of image described in text. We perform the acoustic characterization of a model-scale wind turbine, including the tower and a fully reflective ground surface. The study constitutes the natural extension of the research presented in Rismondo et al. (J. Fluid Mech., 2025, vol. 1024, p. A33), where the isolated rotor (IR) was analysed. We use large-eddy simulation and acoustic analogy. The analysis of pressure over the solid surfaces shows that the rotor produces broadband trailing-edge fluctuations modulated at the blade passing frequency (BPF) by the blade–tower interaction, while the tower exhibits predominantly tonal behaviour at the BPF and its harmonics, as well as low-frequency tower vortex shedding. The tower increases wake asymmetry and turbulent mixing, producing a less coherent wake compared with the IR case. Two main mechanisms rule the near-to-far wake transition: tip-vortex instability and nonlinear interactions between the rotor and the tower induced wakes, enhancing asymmetry and mixing. These dynamics reduce the nonlinear low-frequency acoustic levels in the near wake compared with the IR case, while increasing the sound pressure level and the tonal character in the lateral direction, related to the tower pressure field. In addition, the presence of the tower shapes distinct directivity patterns: radiation in the horizontal plane is nearly isotropic, whereas the rotor-plane directivity is more dipole-shaped, related to the tower, and becomes more pronounced considering the reflective surfaces. Overall, the complete configuration differs significantly from the IR, with measurable differences in surface pressure, wake development and acoustic radiation, emphasizing the role of the tower in both aerodynamics and aeroacoustics.