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Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements

Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements
Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements
This paper is concerned with the acoustic source distribution on aerofoils interacting with a turbulent flow. The source distribution is usually taken to be equal to the pressure jump across the aerofoil, whose behaviour is well understood from classical unsteady aerofoil theory. However, much of this source does not radiate to the far-field. This paper deals with the application of Fourier methods to extract the equivalent source distribution on the aerofoil that radiates perfectly to the far-field. This paper shows that, whilst the actual pressure jump across a flat plate tends to infinity at the leading edge while dropping to zero at the trailing edge (due to the Kutta condition), the equivalent source distribution is more uniform across the aerofoil chord, which explains why the radiation spectrum and single-frequency directivity both exhibit strong oscillations due to interference from coherent sources across the chord. A method for extracting this far-field equivalent source distribution from an array of far-field measurements is proposed in this paper.
Aeroacoustics, Aerofoil interaction noise, Microphone arrays, Source reconstruction
0022-460X
Casagrande Hirono, Fabio
ef8c2e33-96ec-467b-874d-74f0f9bb5f09
Joseph, Phillip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Fazi, Filippo
e5aefc08-ab45-47c1-ad69-c3f12d07d807
Casagrande Hirono, Fabio
ef8c2e33-96ec-467b-874d-74f0f9bb5f09
Joseph, Phillip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Fazi, Filippo
e5aefc08-ab45-47c1-ad69-c3f12d07d807

Casagrande Hirono, Fabio, Joseph, Phillip and Fazi, Filippo (2021) Acoustic source distribution on aerofoils and its reconstruction from far-field array measurements. Journal of Sound and Vibration, 492, [115786]. (doi:10.1016/j.jsv.2020.115786).

Record type: Article

Abstract

This paper is concerned with the acoustic source distribution on aerofoils interacting with a turbulent flow. The source distribution is usually taken to be equal to the pressure jump across the aerofoil, whose behaviour is well understood from classical unsteady aerofoil theory. However, much of this source does not radiate to the far-field. This paper deals with the application of Fourier methods to extract the equivalent source distribution on the aerofoil that radiates perfectly to the far-field. This paper shows that, whilst the actual pressure jump across a flat plate tends to infinity at the leading edge while dropping to zero at the trailing edge (due to the Kutta condition), the equivalent source distribution is more uniform across the aerofoil chord, which explains why the radiation spectrum and single-frequency directivity both exhibit strong oscillations due to interference from coherent sources across the chord. A method for extracting this far-field equivalent source distribution from an array of far-field measurements is proposed in this paper.

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Submitted date: 29 April 2020
Accepted/In Press date: 13 October 2020
e-pub ahead of print date: 14 October 2020
Published date: 3 February 2021
Keywords: Aeroacoustics, Aerofoil interaction noise, Microphone arrays, Source reconstruction

Identifiers

Local EPrints ID: 444664
URI: http://eprints.soton.ac.uk/id/eprint/444664
ISSN: 0022-460X
PURE UUID: c6d33c77-433c-484e-94af-3f9ac37fc002
ORCID for Fabio Casagrande Hirono: ORCID iD orcid.org/0000-0003-4167-6720

Catalogue record

Date deposited: 28 Oct 2020 18:05
Last modified: 26 Nov 2021 06:22

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Contributors

Author: Fabio Casagrande Hirono ORCID iD
Author: Phillip Joseph
Author: Filippo Fazi

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