Identification and Localization of Airfoil Noise Sources at Low Angles of Attack

Abstract

Phased microphone array technique has received much attention for the localization of sound sources. In this paper, this technique is applied to investigate the airfoil self-noise based on a Computational Aeroacoustics (CAA) database. Two dimensional Direct Numerical Simulation (DNS) is conducted of flow over NACA0012 airfoil at low angles of attack and a moderate Reynolds number. Both the mean flow and acoustics results agree well with previous experimental and numerical data. The numerical data then served as an input for the noise identification and localization process. Three beamfoming algorithms are considered. The results of the phased array calculations show that the tonal noise is the dominant source for NACA0012 airfoil operating at low angles of attack and a moderate Reynolds number. With angle of attack increasing, the tonal sources move upstream and the noise strength is enhanced.