Airfoil noise reduction using boundary layer control

Abstract

The flow field and sound radiation of a three component high lift configuration in free-flight was investigated through computational fluid dynamics simulations in conjunction with Ffowcs Williams-Hawkings acoustics solver. The boundary layer blow and suction control method on the inner slat surface has been used to suppress the broadband noise that generated by the high lift configuration. Studies have shown that the free shear layer which originated from the leading edge of the slat can be stabilised and the secondary separation fluids which located on the inner slat surface can be weakened with the boundary layer control. When the suitable boundary layer blow control parameters have been chosen, the computation results show that the fluctuating of the velocity and pressure, turbulence kinetic energy, vorticity and Lamb vector in the slat cove are suppressed by the boundary layer control. The significant reduction of noise level in far-field and the stabilisation of flow field in the slat cove both demonstrate that the boundary layer control is an effective way to control the noise of the high lift configuration.