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On the reduction of aerofoil–turbulence interaction noise associated with wavy leading edges

Published online by Cambridge University Press:  03 March 2016

Jae Wook Kim*
Affiliation:
Aerodynamics and Flight Mechanics Research Group, University of Southampton, Southampton SO17 1BJ, UK
Sina Haeri
Affiliation:
Aerodynamics and Flight Mechanics Research Group, University of Southampton, Southampton SO17 1BJ, UK
Phillip F. Joseph
Affiliation:
Institute of Sound and Vibration Research, University of Southampton, Southampton SO17 1BJ, UK
*
Email address for correspondence: j.w.kim@soton.ac.uk

Abstract

An aerofoil leading-edge profile based on wavy (sinusoidal) protuberances/tubercles is investigated to understand the mechanisms by which they are able to reduce the noise produced through the interaction with turbulent mean flow. Numerical simulations are performed for non-lifting flat-plate aerofoils with straight and wavy leading edges (denoted by SLE and WLE, respectively) subjected to impinging turbulence that is synthetically generated in the upstream zone (free-stream Mach number of 0.24). Full three-dimensional Euler (inviscid) solutions are computed for this study thereby eliminating self-noise components. A high-order accurate finite-difference method and artefact-free boundary conditions are used in the current simulations. Various statistical analysis methods, including frequency spectra, are implemented to aid the understanding of the noise-reduction mechanisms. It is found with WLEs, unlike the SLE, that the surface pressure fluctuations along the leading edge exhibit a significant source-cutoff effect due to geometric obliqueness which leads to reduced levels of radiated sound pressure. It is also found that there exists a phase interference effect particularly prevalent between the peak and the hill centre of the WLE geometry, which contributes to the noise reduction in the mid- to high-frequency range.

Type
Papers
Copyright
© 2016 Cambridge University Press 

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