An Experimental Study of the Flow-induced Noise Created by a Wall-mounted Finite Length Airfoil

Abstract

This paper presents the results of an experimental investigation of the sound produced by flow interaction with a wall-mounted finite length airfoil at low-to-moderate Reynolds number. Acoustic measurements have been taken in an anechoic wind tunnel at a range of Reynolds numbers, angles of attack and for a variety of airfoil aspect ratios (airfoil length to chord ratio) with a single microphone and two perpendicular planar microphone arrays. For comparison, measurements have also been taken with a semi-infinite or twodimensional airfoil and a half-span airfoil with tip flow but no boundary layer impingement. The experimental data is used to examine changes in wall-mounted finite airfoil noise production as a function of Reynolds number, angle of attack and airfoil aspect ratio. Additionally, the data gives insight into the airfoil noise generation mechanisms and the influence of flow at the airfoil tip and wall junction on noise production.