This paper investigates experimentally the reduction of broadband noise radiated by a realistic aerofoil due to interaction with turbulence by the introduction of sinusoidal serrations at the leading edge. A parametric study on serrated leading edge geometries has been carried out to understand the sensitivity of the serration parameters, amplitude 2h and the serration wavelength λ, on the noise reduction by realistic aerofoil geometries. A previous parametric study on this subject by the authors has focused on flat plates, which was shown to capture most, but not all, of the underlying physics. It is shown that the serration amplitude compared to the gust wavelength is the most important factor in determining the degree of noise reduction. It has been observed that the noise reduction generally increases with increasing frequency up until the frequency at which the aerofoil self-noise starts to become significant. This paper also considers the effect of leading edge serrations on the self-noise of the aerofoils and shows that self-noise is substantially reduced at high frequencies. The effectiveness of leading edge serrations is constrained by dominance of self-noise, which can be improved by adding serrations at trailing edge. PIV measurements are also presented to understand the flow around the serrated aerofoils. In this paper we show that, despite introducing substantial modification to the leading edge geometry the flow in the vicinity of the leading edge is well behaved and that aerodynamic performance is not substantially degraded. Finally, computational procedure solving the 3D compressible Euler equation has been employed to compare against the experimental data. Aerodynamics performance has been evaluated on serrated aerofoils are also presented.
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