Emulation of Sound Pressure Level Spectra Based on Numerical Data

Abstract

A largely non-empirical method is presented for the prediction of the total sound emission of a wind turbine. The method is based on acoustic 2D high-fidelity simulations providing sound spectra and directivity functions. The computational effort is limited to a finite number of pre-computed flow conditions, stored to an aeroacoustic catalogue. Currently, the catalogue is consisting of pre-computed aeroacoustic results of independent computations for different airfoils, representative angles of attack, and characteristic flow conditions. Making use of these data, the sound emission of single blade elements is estimated. The suggested method allows for a representation of all operational conditions along the acoustically relevant part of the outer 25 % of the rotor blade. The method is verified at certain test conditions. It is applied to angles of attack and hybrid airfoil geometries not originally included in the catalogue.

A roadmap for required technological advancements to further reduce onshore wind turbine noise impact on the environment

“…High‐fidelity methods in computational fluid dynamics (CFD) and aeroacoustics (CAA) lead a step further toward the next generation of quieter turbines. Today's computational capabilities offer new perspectives to gain detailed insight into the physical phenomena (Arakawa et al, 2005; Delfs et al, 2018; Faßmann et al, 2019; Lele & Nichols, 2014) as illustrated in Figure 1. However, further research and development is needed to enhance reliability and efficiency of current CAA approaches so that they are applicable in the context of fast industrial design loops.…”

“…F I G U R E 1 Instantaneous sound field around a wind turbine blade section as calculated by computational aero-acoustic (CAA) simulation (Source:Faßmann et al, 2019).…”