Reducing aerofoil-turbulence interaction noise through chordwise-varying porosity

Abstract

This paper considers the effects of smoothly varying chordwise porosity of a finite perforated plate on turbulence-aerofoil interaction noise. The aeroacoustic model is made possible through the use of a novel Mathieu function collocation method, rather than a traditional Wiener–Hopf approach, which would be unable to deal with chordwise varying quantities. The main focus is on two bio-inspired porosity distributions, modelled from air flow resistance data obtained from the wings of barn owls (tyto alba) and common buzzards (buteo buteo). Trailing-edge noise is much reduced for the owl-like distribution, but perhaps surprisingly so too is leading-edge noise despite both wings having similar porosity values at the leading edge. A general monotonic variation is then considered indicating that there may indeed be a significant acoustic impact of how the porosity is distributed along the whole chord of the plate, not just its values at the scattering edges. Through this investigation it is found that a plate whose porosity continuously decreases from the trailing edge to a zero-porosity leading edge and in fact generate lower levels of trailing-edge noise than a plate whose porosity remains always at the constant trailing-edge value.

More information

Identifiers

Catalogue record

Export record

Altmetrics