Please use this identifier to cite or link to this item: http://bura.brunel.ac.uk/handle/2438/20854
Title: On the Manipulation of Flow and Acoustic Fields of a Blunt Trailing Edge Aerofoil by Serrated Leading Edges
Authors: Hasheminejad, SM
Chong, TP
Lacagnina, G
Joseph, P
Kim, J-H
Choi, K-S
Omidyeganeh, M
Pinelli, A
Stalnov, O
Keywords: serrated leading edge;blunt trailing edge;tonal noise;streamwise vortices
Issue Date: 16-Jun-2020
Publisher: Acoustical Societey of America
Citation: Hasheminejad, S.M. et al.(2020) 'On the Manipulation of Flow and Acoustic Fields of a Blunt Trailing Edge Aerofoil by Serrated Leading Edges', Journal of the Acoustical Society of America, 147 (6), pp. 3932 - 3947. doi: 10.1121/10.0001377.
Abstract: This paper employs serrated leading edges to inject streamwise vorticity to the downstream boundary layer and wake to manipulate the flow field and noise sources near the blunt trailing edge of an asymmetric aerofoil. The use of a large serration amplitude is found to be effective to suppress the first noise source—bluntness-induced vortex shedding tonal noise—through the destruction of the coherent eigenmodes in the wake. The second noise source is the instability noise, which is produced by the interaction between the boundary layer instability and separation bubble near the blunt edge. The main criterion needed to suppress this noise source is related to a small serration wavelength because, through the generation of more streamwise vortices, it would facilitate a greater level of destructive interaction with the separation bubble. If the leading edge has both a large serration amplitude and wavelength, the interaction between the counter-rotating vortices themselves would trigger a turbulent shear layer through an inviscid mechanism. The turbulent shear layer will produce strong hydrodynamic pressure fluctuations to the trailing edge, which then scatter into broadband noise and transform into a trailing edge noise mechanism. This would become the third noise source that can be identified in several serrated leading edge configurations. Overall, a leading edge with a large serration amplitude and small serration wavelength appears to be the optimum choice to suppress the first and second noise sources and, at the same time, avoid the generation of the third noise source.
URI: https://bura.brunel.ac.uk/handle/2438/20854
DOI: https://doi.org/10.1121/10.0001377
ISSN: 0001-4966
Other Identifiers: ORCiD: Seyed Mohammad Hasheminejad https://orcid.org/0000-0002-7717-0820
ORCiD: Tze Pei Chong https://orcid.org/0000-0002-5272-3943
ORCiD: Giovanni Lacagnina https://orcid.org/0000-0002-8038-1127
ORCiD: Phillip Joseph https://orcid.org/0000-0001-9299-8629
ORCiD: Kwing-So Choi https://orcid.org/0000-0002-8383-8057
ORCiD: Alfredo Pinelli https://orcid.org/0000-0001-5564-9032
ORCiD: Oksana Stalnov https://orcid.org/0000-0002-3853-1507
Appears in Collections:Dept of Mechanical and Aerospace Engineering Research Papers

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