Downstream perforations for the reduction of turbulence-aerofoil interaction noise: Part I - experimental investigation

Palleja Cabre, Sergi, Paruchuri, Chaitanya, Joseph, Phillip, Priddin, Matthew and Ayton, Lorna (2021) Downstream perforations for the reduction of turbulence-aerofoil interaction noise: Part I - experimental investigation. In AIAA AVIATION 2021 FORUM. (doi:10.2514/6.2021-2149).

Abstract

Aerofoils operating in a turbulent flow are an efficient source of noise radiation by scattering vorticity into sound at the leading edge. Much work has been undertaken demonstrating the effectiveness by which serrations, or leading edge profiles, and porosity introduced onto the leading edge can substantially reduce broadband leading-edge interaction noise. In this paper, a novel perforated leading edge design is proposed which is capable of providing low-frequency noise attenuation. The design consists of one or more rows of perforated holes downstream of the leading edge of the aerofoil. A systematic parametric study on the sensitivity of noise reduction performance to hole diameters, hole spacing and hole locations is performed in this paper. Overall power level noise reductions of up to 1.75 dB have been measured. A simple analytical model is also proposed and compared with the measured data to explain the noise reduction mechanisms. A key finding of this paper is that the proposed treatment can `disconnect' the rigid section downstream of the perforations and effectively behave as an aerofoil with shorter chord.

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Contributors

Author: Sergi Palleja Cabre

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