Modeling wind farm noise emission and propagation: effects of flow layout

Abstract: This study demonstrates how wind farm flow physics influence noise generation and downstream propagation through numerical simulations. The flow field is modeled using large-eddy simulations (LES), and the time-averaged output serves as input to acoustic models that predict wind turbine noise. In the first turbine row, turbulence-induced noise (TIN) and trailing edge noise (TEN) contribute equally, with TIN dominating at low frequencies and TEN at higher frequencies. Downstream, TEN decreases due to lower wind speeds, while TIN mostly persists due to increased turbulence dissipation. These effects are more pronounced in aligned wind farms, where stronger wake interactions occur, than in staggered layouts. However, staggered farms produce more noise overall because turbines operate at higher wind speeds.Additionally, wind farm flow significantly affects sound propagation downwind. The wake superposition modifies sound focusing leading to different amplification area than for an isolated turbine. For a staggered layout it particularly shows enhanced sound focusing downwind due to the position of the turbine wakes. This leads to higher sound levels and higher amplitude modulation downwind for the wind farm compared to an aligned layout. These phenomena are not captured by models based on isolated turbines. These findings underscore the importance of integrating flow and acoustic models to more accurately assess the environmental impact of wind farms.