Physical mechanisms and performance of slitted leading-edge profiles for the reduction of broadband aerofoil interaction noise

Aerofoil Turbulence Interaction (ATI) noise is an inviscid phenomenon generated by the impingement of turbulent flows onto the leading-edge of an aerofoil. This paper deals with a novel leading-edge serration geometry, composed of narrow slits, to reduce ATI noise. These profiles have been recently found to provide significantly better noise reductions than conventional leading edge geometries. A numerical and analytic investigation is performed into the mechanism and performance of its noise reduction. The far-field radiation is shown to be influenced by a system of induced vortices affecting the distribution of sources on the flat-plate and by destructive interference between the two sources generated at both ends of the slit. A simple two-source model is developed to predict the far-field noise reduction obtained and compared to straight leading-edge aerofoils.