The Aerodynamic and Aeroacoustic Effect of Passive High Frequency Oscillating Trailing Edge Flaplets

Aerofoil noise reduction is a topic of great interest at the present time and as such many strategies have been presented, in previous literatures whether they are trailing edge serrations, leading edge undulations or porous aerofoils, to name a few. The present study investigates a bio-inspired solution where an array of passive flexible elements, known as flaplets, are extended over the trailing edge of the aerofoil and are allowed to oscillate freely in the flow field. The aerofoil in used in the present study is a NACA 0012 and has been analysed by using both time resolved particle image velocimetry (TR-PIV), in a close circuit wind tunnel, and aeroacoustic measurements in an open jet wind tunnel at moderate chord based Reynolds numbers; ranging from 50,000 to 350,000. The results show a clear reduction in tonal noise with a clear region of maximum noise reduction scaled with \(u_\infty ^\text {1.5}\).