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Near- to far-field characteristics of acoustic radiation through plug flow jets

Near- to far-field characteristics of acoustic radiation through plug flow jets
Near- to far-field characteristics of acoustic radiation through plug flow jets
This paper reports a theoretical study of the radiation of sound through jet exhausts. It focuses on the transition from near field to far field by considering the features of the near-field solution and how these features translate to the far field. The main focus of this work is the importance in some cases of lateral waves radiating from the jet. While the presence of lateral waves has long been recognized, there has been no systematic investigation of the practical consequences of these waves in the prediction of sound propagation through round jets. The physical mechanisms involved in the generation of these waves are presented as well as the conditions under which they become significant. Another issue is the possibility of “channeled waves” inside the jet associated with strong sound radiation in the forward arc. This paper also discusses the validity of the far-field approximation when lateral waves are present. It is shown that the standard far-field approximation can be improved by adding correction terms that account for the presence of the lateral waves and channeled waves. The challenge posed to computational aeroacoustics by these near-field effects is also discussed.
acoustic field, acoustic intensity, acoustic noise, acoustic wave propagation, acoustic wave refraction, aeroacoustics, aerodynamics, approximation theory, exhaust systems, jets
0001-4966
2755-2766
Gabard, G.
bfd82aee-20f2-4e2c-ad92-087dc8ff6ce7
Gabard, G.
bfd82aee-20f2-4e2c-ad92-087dc8ff6ce7

Gabard, G. (2008) Near- to far-field characteristics of acoustic radiation through plug flow jets. Journal of the Acoustical Society of America, 124 (5), 2755-2766. (doi:10.1121/1.2977609).

Record type: Article

Abstract

This paper reports a theoretical study of the radiation of sound through jet exhausts. It focuses on the transition from near field to far field by considering the features of the near-field solution and how these features translate to the far field. The main focus of this work is the importance in some cases of lateral waves radiating from the jet. While the presence of lateral waves has long been recognized, there has been no systematic investigation of the practical consequences of these waves in the prediction of sound propagation through round jets. The physical mechanisms involved in the generation of these waves are presented as well as the conditions under which they become significant. Another issue is the possibility of “channeled waves” inside the jet associated with strong sound radiation in the forward arc. This paper also discusses the validity of the far-field approximation when lateral waves are present. It is shown that the standard far-field approximation can be improved by adding correction terms that account for the presence of the lateral waves and channeled waves. The challenge posed to computational aeroacoustics by these near-field effects is also discussed.

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More information

Published date: November 2008
Keywords: acoustic field, acoustic intensity, acoustic noise, acoustic wave propagation, acoustic wave refraction, aeroacoustics, aerodynamics, approximation theory, exhaust systems, jets
Organisations: Acoustics Group, Fluid Dynamics & Acoustics Group

Identifiers

Local EPrints ID: 65223
URI: https://eprints.soton.ac.uk/id/eprint/65223
ISSN: 0001-4966
PURE UUID: 2a675bf0-36f0-44c9-aecc-7b09d3929906

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Date deposited: 05 Feb 2009
Last modified: 13 Mar 2019 20:19

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