Investigation and prediction of transitional airfoil self-noise

Abstract

Direct numerical simulations (DNS) have been conducted of the flow over NACA-0006 and NACA-0012 airfoils. The airfoil flows have been found to exhibit pronounced transitional phenomena and multiple sources of noise have been observed. Data transformed to the frequency domain, and third-octave averaged, reveal that for 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 the flow events in the transition/reattachment region on the suction side. Cross-correlations of acoustic and hydrodynamic quantities, combined with ray-acoustic theory, are shown to identify the main source locations. Eve..