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.