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On the superior performance of leading edge slits over serrations for the reduction of aerofoil interaction noise

On the superior performance of leading edge slits over serrations for the reduction of aerofoil interaction noise
On the superior performance of leading edge slits over serrations for the reduction of aerofoil interaction noise

Aerofoils operating in a turbulent flow are an efficient source of noise radiation by scattering vorticity into sound at the leading edge. Much work has now been undertaken demonstrating the effectiveness by which serrations, or undulations, introduced onto the leading edge, can substantially reduce broadband leading edge interaction noise. However, all of this work is focused on sinusoidal leading edge serration profiles. In this paper, a family of alternative serration profiles are proposed that are capable of providing significantly greater noise reductions than single-wavelength serrations at optimal conditions. This new family of profiles will be shown to reduce interaction noise through a fundamentally different noise reduction mechanism than conventional single-wavelength profiles. Unlike single-wavelength profiles, which produce a single compact dominant source region per serration wavelength, these new profiles are designed to produce two dominant compact sources per serration wavelength of the same source strength, that are separated in the streamwise direction. Since these sources are arranged to be closer together than the turbulence length-scale, they are highly coherent and therefore radiate with a difference in phase. A frequency therefore exists at which the sources are exactly 180° out of phase leading to very high levels of noise reduction in the far field.

American Institute of Aeronautics and Astronautics
Chaitanya, Paruchuri
5c1def64-6347-4be3-ac2d-b9f6a314b81d
Joseph, Phillip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Ayton, Lorna J.
58d53540-2704-4eaa-acfc-dcaee78637ac
Chaitanya, Paruchuri
5c1def64-6347-4be3-ac2d-b9f6a314b81d
Joseph, Phillip
9c30491e-8464-4c9a-8723-2abc62bdf75d
Ayton, Lorna J.
58d53540-2704-4eaa-acfc-dcaee78637ac

Chaitanya, Paruchuri, Joseph, Phillip and Ayton, Lorna J. (2018) On the superior performance of leading edge slits over serrations for the reduction of aerofoil interaction noise. In 2018 AIAA/CEAS Aeroacoustics Conference. American Institute of Aeronautics and Astronautics.. (doi:10.2514/6.2018-4107).

Record type: Conference or Workshop Item (Paper)

Abstract

Aerofoils operating in a turbulent flow are an efficient source of noise radiation by scattering vorticity into sound at the leading edge. Much work has now been undertaken demonstrating the effectiveness by which serrations, or undulations, introduced onto the leading edge, can substantially reduce broadband leading edge interaction noise. However, all of this work is focused on sinusoidal leading edge serration profiles. In this paper, a family of alternative serration profiles are proposed that are capable of providing significantly greater noise reductions than single-wavelength serrations at optimal conditions. This new family of profiles will be shown to reduce interaction noise through a fundamentally different noise reduction mechanism than conventional single-wavelength profiles. Unlike single-wavelength profiles, which produce a single compact dominant source region per serration wavelength, these new profiles are designed to produce two dominant compact sources per serration wavelength of the same source strength, that are separated in the streamwise direction. Since these sources are arranged to be closer together than the turbulence length-scale, they are highly coherent and therefore radiate with a difference in phase. A frequency therefore exists at which the sources are exactly 180° out of phase leading to very high levels of noise reduction in the far field.

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More information

e-pub ahead of print date: 24 June 2018
Published date: 25 June 2018
Venue - Dates: AIAA/CEAS Aeroacoustics Conference, 2018, Atlanta, United States, 2018-06-25 - 2018-06-29

Identifiers

Local EPrints ID: 424576
URI: https://eprints.soton.ac.uk/id/eprint/424576
PURE UUID: 43f573ed-d2a9-445f-a9cc-de3a88714196

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Date deposited: 05 Oct 2018 11:38
Last modified: 17 Jan 2019 17:30

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