Prediction Method for Broadband Noise from Unsteady Flow in a Slat Cove

Abstract

Noise from high-lift devices such as slats and flaps can contribute significantly 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 midfrequencies. The objective 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 flow past the wing is uniform. A boundary element method is used to find Green’s function for wave propagation in a moving medium in the presence of the wing. The noise in the far field is then predicted by forming a convolution of Green’s function with the modeled sources. The attractive feature of this prediction scheme is the quick computational time, which makes it suitable for new design and control strategies.