Acoustic source identification for transitional airfoil flows using cross correlations

Abstract

Direct numerical simulations have been conducted of the flow over NACA-0006 and NACA-0012 airfoils. For all cases multiple sources of noise have been observed. At low frequencies, the contribution of trailing-edge noise radiation is significant, while for the high frequencies, the radiated noise appears to be due only to flow events in the transition/reattachment region on the suction side. Cross correlations of acoustic and hydrodynamic quantities, combined with ray-acoustic theory, are used to identify the main source locations. While the physical origin of trailing-edge noise can be clearly identified using these methods, the situation is less clear for additional noise sources that radia..