A numerical phased array approach to model flow sound sources in aeroacoustic simulations
(English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568Article in journal (Other academic) Submitted
An application of phased array methods to numerical data is presented, aimed at modelling flow sound sources from aeroacoustic simulations. Based on phased array data extracted from the compressible flow simulations, sound source strengths are computed on a set of points in the source region using phased array techniques assuming monopole propagation. Two phased array techniques are used to compute the source strengths: an approach using a Moore-Penrose pseudo-inverse and a beamforming approach using linear programming (LP) deconvolution. The first approach gives a model of correlated sources for the acoustic field generated from the flow expressed in a matrix of cross- and auto-power spectral values, whereas the second approach results in a model of uncorrelated sources expressed in a vector of auto-power spectral values. The accuracy of the model is estimated by computing the acoustic spectrum at a far-field observer. The modelling approach is tested first on an analytical case with known point sources. It is then applied to the example of the flow around a submerged air inlet. The far-field spectra obtained from the source models for two different flow conditions show a good agreement with the spectra obtained with a Ffowcs Williams and Hawkings integral. Various configurations for the phased array and for the sources are used. The LP beamforming approach shows better robustness to changes in the number of probes and sources than the pseudo-inverse approach. The good results obtained with this simulation case demonstrate the potential of the phased array approach as a modelling tool for aeroacoustic simulations.
Place, publisher, year, edition, pages
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:kth:diva-192164OAI: oai:DiVA.org:kth-192164DiVA: diva2:958288
QC 201609212016-09-062016-09-062016-09-21Bibliographically approved