Broadband Noise from the Unsteady Flow in a Slat Cove

Abstract

Noise from high-lift devices such as slats and aps can contribute signicantly to the overall aircraft sound pressure levels, particularly during approach. The acoustic spectrum of the noise radiated from slats exhibits two distinct features. There is a high-frequency tonal noise component, and a high-energy broadband component ranging from low to mid-frequencies. The objective of the present paper is to predict the broadband slat noise. The broadband noise is predicted using a two-step process. First the noise sources are modeled based on the local turbulence information. Then, the sound from these sources is propagated by assuming that the ow past the wing is uniform. A Boundary Element Method is used to nd the Green’s function for wave propagation in a moving medium in the presence of the wing. The noise in the far eld is then predicted by forming a convolution of the Green’s function with the modeled sources. The attractive feature of this prediction scheme is the relatively quick computational time, which makes it suitable for new design and control strategies.