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Airfoil noise reductions through leading edge serrations

Airfoil noise reductions through leading edge serrations
Airfoil noise reductions through leading edge serrations
This paper provides an experimental investigation into the use of leading edge (LE) serrations as a means of reducing the broadband noise generated due to the interaction between the aerofoil’s LE and impinging turbulence. Experiments are performed on a flat plate in an open jet wind tunnel. Grids are used to generate isotropic homogeneous turbulence. The leading edge serrations are in the form of sinusoidal profiles of wavelengths, ?, and amplitudes, 2h. The frequency and amplitude characteristics are studied in detail in order to understand the effect of LE serrations on noise reduction characteristics and are compared with straight edge baseline flat plates. Noise reductions are found to be insignificant at low frequencies but significant in the mid frequency range (500 Hz–8 kHz) for all the cases studied. The flat plate results are also compared to the noise reductions obtained on a serrated NACA-65 aerofoil with the same serration profile. Noise reductions are found to be significantly higher for the flat plates with a maximum noise reduction of around 9 dB compared with about 7 dB for the aerofoil. In general, it is observed that the sound power reduction level (?PWL) is sensitive to the amplitude, 2h of the LE serrations but less sensitive to the serration wavelength, ?. Thus, this paper sufficiently demonstrates that the LE amplitude acts as a key parameter for enhancing the noise reduction levels in flat plates and aerofoils.
1070-6631
025109/1-025109/17
Narayanan, S.
496a8ad5-626a-442f-b61a-cd2ab3f7731e
Chaitanya, P.
5c1def64-6347-4be3-ac2d-b9f6a314b81d
Haeri, S.
8e2f9ded-d4c7-4ae3-9fdb-db91f5f9ba9e
Joseph, P.F.
9c30491e-8464-4c9a-8723-2abc62bdf75d
Kim, J.W.
fedabfc6-312c-40fd-b0c1-7b4a3ca80987
Polacsek, C.
20a2423a-93a0-414f-ae65-1328a75af49f
Narayanan, S.
496a8ad5-626a-442f-b61a-cd2ab3f7731e
Chaitanya, P.
5c1def64-6347-4be3-ac2d-b9f6a314b81d
Haeri, S.
8e2f9ded-d4c7-4ae3-9fdb-db91f5f9ba9e
Joseph, P.F.
9c30491e-8464-4c9a-8723-2abc62bdf75d
Kim, J.W.
fedabfc6-312c-40fd-b0c1-7b4a3ca80987
Polacsek, C.
20a2423a-93a0-414f-ae65-1328a75af49f

Narayanan, S., Chaitanya, P., Haeri, S., Joseph, P.F., Kim, J.W. and Polacsek, C. (2015) Airfoil noise reductions through leading edge serrations. Physics of Fluids, 27 (2), 025109/1-025109/17. (doi:10.1063/1.4907798).

Record type: Article

Abstract

This paper provides an experimental investigation into the use of leading edge (LE) serrations as a means of reducing the broadband noise generated due to the interaction between the aerofoil’s LE and impinging turbulence. Experiments are performed on a flat plate in an open jet wind tunnel. Grids are used to generate isotropic homogeneous turbulence. The leading edge serrations are in the form of sinusoidal profiles of wavelengths, ?, and amplitudes, 2h. The frequency and amplitude characteristics are studied in detail in order to understand the effect of LE serrations on noise reduction characteristics and are compared with straight edge baseline flat plates. Noise reductions are found to be insignificant at low frequencies but significant in the mid frequency range (500 Hz–8 kHz) for all the cases studied. The flat plate results are also compared to the noise reductions obtained on a serrated NACA-65 aerofoil with the same serration profile. Noise reductions are found to be significantly higher for the flat plates with a maximum noise reduction of around 9 dB compared with about 7 dB for the aerofoil. In general, it is observed that the sound power reduction level (?PWL) is sensitive to the amplitude, 2h of the LE serrations but less sensitive to the serration wavelength, ?. Thus, this paper sufficiently demonstrates that the LE amplitude acts as a key parameter for enhancing the noise reduction levels in flat plates and aerofoils.

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Accepted/In Press date: 23 January 2015
e-pub ahead of print date: 13 February 2015
Organisations: Faculty of Engineering and the Environment

Identifiers

Local EPrints ID: 374405
URI: http://eprints.soton.ac.uk/id/eprint/374405
ISSN: 1070-6631
PURE UUID: f320ed3b-10f1-4f28-a407-51dce767fd39
ORCID for J.W. Kim: ORCID iD orcid.org/0000-0003-0476-2574

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Date deposited: 17 Feb 2015 13:46
Last modified: 18 Feb 2021 17:03

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