Influence of curvature distribution smoothing on the reduction of aerofoil self-noise
International Journal of Numerical Methods for Heat & Fluid Flow
ISSN: 0961-5539
Article publication date: 2 February 2023
Issue publication date: 24 April 2023
Abstract
Purpose
This paper aims to investigate the influence of smooth curvature distributions on the self-noise of a low Reynolds number aerofoil and to unveil the flow mechanisms in the phenomenon.
Design/methodology/approach
In this paper, large Eddy simulation (LES) approach was performed to investigate the unsteady aerodynamic performance of both the original aerofoil E387 and the redesigned aerofoil A7 in a time-dependent study of boundary layer characteristics at Reynolds number 100,000 and angle of attack (AoA) 4-degree. The aerofoil A7 is redesigned from E387 by removing the irregularities in the surface curvature distributions and keeping a nearly identical geometry. Flow vorticity magnitude of both aerofoils, along with the spectra of the vertical fluctuating velocity component and noise level, are analysed to demonstrate the bubble flapping process near the trailing edge (TE) and the vortex shedding phenomenon.
Findings
This paper provides quantitative insights about how the flapping process of the laminar separation bubble (LSB) within the boundary layer near the TE affects the aerofoil self-noise. It is found that the aerofoil A7 with smooth curvature distributions presents a 10% smaller LSB compared to the aerofoil E387 at Reynolds number 100,000 and AoA 4-degree. The LES results also suggest that curvature distribution smoothing leads to a 6.5% reduction in overall broadband noise level.
Originality/value
This paper fulfils an identified need to reveal the unknown flow structure and the boundary layer characteristics that resulted in the self-noise reduction phenomenon yielded by curvature distribution smoothing.
Keywords
Acknowledgements
The research was supported by the Royal Society International Exchanges 2019 Cost Share Programme (Grant No. IEC\NSFC\191409) and the Northern Accelerator CCF Feasibility Project (Grant No. NACCF228).
Citation
Shen, X., Avital, E., Ikram, Z., Yang, L., Korakianitis, T. and Dala, L. (2023), "Influence of curvature distribution smoothing on the reduction of aerofoil self-noise", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 33 No. 4, pp. 1379-1393. https://doi.org/10.1108/HFF-07-2022-0418
Publisher
:Emerald Publishing Limited
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