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Effect of serrated trailing edges on aerofoil tonal noise

Published online by Cambridge University Press:  13 October 2020

Matthieu B. R. Gelot Open the ORCID record for Matthieu B. R. Gelot [Opens in a new window]  and
Jae Wook Kim Open the ORCID record for Jae Wook Kim [Opens in a new window]
Matthieu B. R. Gelot*
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Highfield, SouthamptonSO17 1BJ, UK
Jae Wook Kim
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Highfield, SouthamptonSO17 1BJ, UK
*
†Email address for correspondence: m.b.r.gelot@soton.ac.uk
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Abstract

A wall-resolved large-eddy simulation of a symmetric Joukowski aerofoil with a 12 % thickness at a Reynolds number of 250 000, a Mach number of 0.4 and zero incidence angle is performed in order to investigate the effect of using a serrated trailing edge on the acoustic feedback event that generates a tonal noise. The acoustic feedback is investigated in detail to emphasise the interaction between the upstream travelling acoustic expansion wave and the laminar separation bubble. The simulation shows that the serrated trailing edges may result in a significant reduction of the tonal noise. This paper provides detailed investigations into the noise reduction mechanisms. The main finding is that the presence of a serrated trailing edge decreases the amplitude of the acoustic source pressure in the transitional region and gives rise to destructive phase interference in the wall pressure fluctuations in the vicinity of the trailing edge which weakens the acoustic feedback loop.

JFM classification

Acoustics: Aeroacoustics Turbulent Flows: Turbulence simulation
Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 904 , 10 December 2020 , A30
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Copyright
© The Author(s), 2020. Published by Cambridge University Press

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