Discrete Tonal Noise Prediction of Arbitrary Rotors Configurations Using Rings Source Fields
* Presenting author
Sound fields generated by rotating devices such as electronic fans, propellers or helicopter rotors are characterized by complex diffraction patterns at different regions in space, especially at high harmonic numbers and/or large number of blades. This complexity makes the noise prediction of such devices computationally and scientifically challenging. In the present work, a method for predicting the tonal noise of rotating devises at the blade passing frequency (BPF) and its harmonics is presented. The method replaces the presence of the rotor by a suitable combination of source rings with variable amplitude and phase, i.e. dipole (to model loading noise) and monopole (to model thickness noise) rings. Concerning the sources computation: (i) the thickness source solely depends on the geometry of the rotor; (ii) the loading sources are estimated using the pressure over the rotor’s surface computed by means of a CFD analysis. For the acoustic propagation analysis, such rings of sources are placed in a finite element (FE) context for taking into account complex geometries and mean flow heterogeneities in the acoustic propagation. The numerical case selected showcases the noise prediction of an electronic cooling fan with three different geometry configurations. Finally, the numerical results are validated against experimental data.