Simulation of aerodynamically generated noise using the wave expansion method

Hammar, Johan; O’Reilly, Ciarán J.; Efraimsson, Gunilla

doi:10.2514/6.2016-3024

Cited by 1 publication

(1 citation statement)

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“…Otherwise the source terms of the acoustic analogies can be evaluated from the flow quantities, providing a model for the sources. Although well detailed, this model is not straigthforward to use as input to propagation solvers [7,8] as it requires interpolation between the flow and the acoustic mesh, estimations of derivatives etc. In many applications, it can be useful to get a simpler model, which is the motivation behind this work.…”

Section: Introductionmentioning

confidence: 99%

Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array

Pignier

O’Reilly

Boij

2017

Journal of Sound and Vibration

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PostprintThis is the accepted version of a paper published in Journal of Sound and Vibration. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Pignier, N., O'Reilly, C J., Boij, S. (2017) Identifying equivalent sound sources from aeroacoustic simulations using a numerical phased array. Journal of Sound and Vibration AbstractAn application of phased array methods to numerical data is presented, aimed at identifying equivalent flow sound sources from aeroacoustic simulations. Based on phased array data extracted from 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 dual linear programming (dual-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 equivalent source model is estimated by computing the acoustic spectrum at a far-field observer. The 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 are in good agreement with the spectra obtained with a Ffowcs Williams-Hawkings integral, showing the accuracy of the source model from the observer's standpoint. Various configurations for the phased array and for the sources are used. The dual-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.

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Section: Introductionmentioning

confidence: 99%