Darrieus wind turbine noise propagation in urban environments using ray tracing

The noise radiated from a Darrieus vertical axis wind turbine (VAWT) is propagated in different idealized urban scenes using a 2.5D ray-based engineering method. Noise measurements and simulated Lattice Boltzmann Method (LBM) results from a Darrieus VAWT are employed as a noise source to perform ray tracing around various idealized benchmark urban scenes, ranging from single isolated buildings to multiple building configurations. Noise maps, 1.5 m above the ground and along different vertical planes around the isolated building cases, illustrate the effect of the sound speed gradient, resulting in higher noise levels downwind and producing complex interference patterns. The more realistic LBM source directivity also illustrates the induced asymmetry in noise propagation that can affect more some regions of the buildings. When the wind turbine source is positioned on a high-rise building, lower noise levels near the ground are observed. In multiple building configurations, wind turbines mounted on rooftops exhibit lower noise levels compared to those mounted directly on masts, emphasizing the screening effect of the roof. The model is also applied to a wind turbine in a realistic urban setting around a central square in Grenoble, France, capturing the complex interference, reflection, and diffraction patterns. Such noise maps could be beneficial for the certification of wind turbines installed in urban environments.