Investigation into the mechanisms of propeller-wing interaction noise

Abstract

This paper presents the preliminary experimental investigation of the dominant noise sources from the propeller-wing configuration at hover conditions. A parametric study is performed to investigate the sensitivity of the radiated noise to the axial separation distance z and the offset separation distance d between propeller and wing. This study is performed on even and odd bladed propellers across various azimuthal and polar angles. It was observed that null interaction acoustic pressure is obtained exactly below the wing for an even number of blades while for an odd number of blades null was observed at even harmonics. Analytical predictions for Potential-field, viscous-wake and tip vortex interactions for tonal noise is used to prove this hypothesis for zero offset position in the current paper. Significant increase in the tonal and broadband noise is observed for an offset wing configuration when the wing is placed in tip vortex flow. One of the possible reasons behind this is attributed to the enhanced interaction of tip vortex-wing interactions due to interaction length on the wing.