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"Buzz-saw" noise: a comparison of modal measurements with an improved prediction method

"Buzz-saw" noise: a comparison of modal measurements with an improved prediction method
"Buzz-saw" noise: a comparison of modal measurements with an improved prediction method
“Buzz-saw” noise is radiated from a turbofan inlet duct when the fan tip speed is supersonic. In a recent article the effect of an acoustic liner on buzz-saw noise has been examined. Spectral measurements in a rigid and an acoustically lined inlet duct have been compared. Also these measurements have been utilized to assess a buzz-saw noise prediction method. The prediction method is based on a one-dimensional nonlinear propagation model. Sound absorption by an acoustic lining can be included in the model. In this article, the buzz-saw noise prediction method is improved by the inclusion in the modelling of the effect of a boundary layer on absorption of sound in a lined duct. Also, modal measurements from a circumferential microphone array have been examined. These show that the principal source of buzz-saw noise is not always the rotor-alone pressure field. Non-rotor-alone scattered tones can be a significant source of buzz-saw noise at low supersonic fan speeds. The numerical simulations, which only predict the rotor-alone tones, have been re-evaluated in light of these new modal measurements.
0022-460X
419-443
McAlpine, A.
aaf9e771-153d-4100-9e84-de4b14466ed7
Fisher, M.J.
9662c037-03c2-4a45-9b58-9b83fe5b323d
Tester, B.J.
1bd4a793-131b-4173-93cc-3eca70b2d116
McAlpine, A.
aaf9e771-153d-4100-9e84-de4b14466ed7
Fisher, M.J.
9662c037-03c2-4a45-9b58-9b83fe5b323d
Tester, B.J.
1bd4a793-131b-4173-93cc-3eca70b2d116

McAlpine, A., Fisher, M.J. and Tester, B.J. (2007) "Buzz-saw" noise: a comparison of modal measurements with an improved prediction method. Journal of Sound and Vibration, 306 (3-5), 419-443. (doi:10.1016/j.jsv.2007.04.053).

Record type: Article

Abstract

“Buzz-saw” noise is radiated from a turbofan inlet duct when the fan tip speed is supersonic. In a recent article the effect of an acoustic liner on buzz-saw noise has been examined. Spectral measurements in a rigid and an acoustically lined inlet duct have been compared. Also these measurements have been utilized to assess a buzz-saw noise prediction method. The prediction method is based on a one-dimensional nonlinear propagation model. Sound absorption by an acoustic lining can be included in the model. In this article, the buzz-saw noise prediction method is improved by the inclusion in the modelling of the effect of a boundary layer on absorption of sound in a lined duct. Also, modal measurements from a circumferential microphone array have been examined. These show that the principal source of buzz-saw noise is not always the rotor-alone pressure field. Non-rotor-alone scattered tones can be a significant source of buzz-saw noise at low supersonic fan speeds. The numerical simulations, which only predict the rotor-alone tones, have been re-evaluated in light of these new modal measurements.

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More information

Published date: 9 October 2007

Identifiers

Local EPrints ID: 49616
URI: https://eprints.soton.ac.uk/id/eprint/49616
ISSN: 0022-460X
PURE UUID: 133ef393-6fb9-404a-b615-2a127083175c
ORCID for A. McAlpine: ORCID iD orcid.org/0000-0003-4189-2167

Catalogue record

Date deposited: 23 Nov 2007
Last modified: 14 Mar 2019 01:49

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