Experimental study of the effect of a small 2D excrescence placed on the slat cove surface of an airfoil on its acoustic noise

Resumo

© 2015, American Institute of Aeronautics and Astronautics Inc, AIAA. All Rights Reserved.This paper refers to an aeroacoustic experimental study of a slat containing a twodimensional protrusion installed at the interior of its cove, representing a sealing device. The experiments were based on a 2D model of the three-element MD30P30N geometry with 500 mm stowed chord. Four different positions of the seal were tested. The effect of the seal was assessed in what concerns the pressure coefficient on the airfoil surface, the frequency content of radiated noise and noise source field using conventional beamforming technique combined with DAMAS deconvolution method. This study was based on experimental data obtained at a wind tunnel of closed test section, using an array containing 62 microphones. Different angles of attack and free-stream speeds were evaluated. The main results evidenced that the presence of a seal at slat cove has a huge impact at its acoustic frequency spectrum components. Depending on the sealing device position, it could attenuate or intensify the low frequency tonal peaks, which are characteristic of slat models at low Reynolds number regime.