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Active control of buzz-saw tones: experiment and theory

Active control of buzz-saw tones: experiment and theory
Active control of buzz-saw tones: experiment and theory
This paper discusses some theoretical and experimental issues related to the active control of buzz-saw tones radiated from an aircraft engine inlet at takeoff. Buzz-saw tones occur when the rotor tip speed becomes supersonic. It arises due to the formation of shocks at the blade tips, which then propagate non-linearly along the engine duct. Buzz-saw noise comprises a series of tones harmonically related to the shaft rotation frequency (Engine Orders). Moreover, it has been shown that the noise at each Engine Order comprises just one single spinning mode. Whilst there has been considerable work aimed at assessing the feasibility of active control for reducing the tones due to rotor - stator interaction, buzz-saw noise has been overlooked. This is surprising given the low frequencies at which Buzz-Saw noise occurs, and its simple modal content, which both suggest that buzz-saw noise is particularly suited to active control. This paper describes various control strategies for reducing buzz-saw noise. The paper concludes with the results of a laboratory experiment aimed at demonstrated experimentally the effectiveness with which a single spinning mode, characteristic of an EO = 3 buzz-saw tone, can be controlled. Reductions in excess of 14dB are reported at some frequencies.
1475-472X
1-15
Joseph, Philip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Wilkinson, Matthew
74a4fe87-1b85-4e92-98b2-1b21b31b1a3b
Joseph, Philip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Wilkinson, Matthew
74a4fe87-1b85-4e92-98b2-1b21b31b1a3b

Joseph, Philip and Wilkinson, Matthew (2007) Active control of buzz-saw tones: experiment and theory. International Journal of Aeroacoustics, 6 (1), 1-15. (doi:10.1260/147547207780440785).

Record type: Article

Abstract

This paper discusses some theoretical and experimental issues related to the active control of buzz-saw tones radiated from an aircraft engine inlet at takeoff. Buzz-saw tones occur when the rotor tip speed becomes supersonic. It arises due to the formation of shocks at the blade tips, which then propagate non-linearly along the engine duct. Buzz-saw noise comprises a series of tones harmonically related to the shaft rotation frequency (Engine Orders). Moreover, it has been shown that the noise at each Engine Order comprises just one single spinning mode. Whilst there has been considerable work aimed at assessing the feasibility of active control for reducing the tones due to rotor - stator interaction, buzz-saw noise has been overlooked. This is surprising given the low frequencies at which Buzz-Saw noise occurs, and its simple modal content, which both suggest that buzz-saw noise is particularly suited to active control. This paper describes various control strategies for reducing buzz-saw noise. The paper concludes with the results of a laboratory experiment aimed at demonstrated experimentally the effectiveness with which a single spinning mode, characteristic of an EO = 3 buzz-saw tone, can be controlled. Reductions in excess of 14dB are reported at some frequencies.

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Published date: January 2007

Identifiers

Local EPrints ID: 50467
URI: http://eprints.soton.ac.uk/id/eprint/50467
ISSN: 1475-472X
PURE UUID: 4bec81b0-913d-4dd1-bb92-66d516c50ccc

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Date deposited: 26 Feb 2008
Last modified: 15 Mar 2024 10:06

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Contributors

Author: Philip Joseph
Author: Matthew Wilkinson

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