Shadowgraph flow visualization of isolated tiltrotor and rotor/wing wakes

Abstract

Shadowgraph flow visualization images were acquired from a 0.184-scale tiltrotor and wing in hover. Measurements and details of the vortex core structure were examined as a function of thrust condition and wake age. Experimental data for the isolated rotor wake geometry and rotor wake interactions with a semi-span wing and image plane were acquired. Quantitative measurements and comparisons of wake geometry and distortion were made for three configurations: the isolated rotor, rotor/wing, and rotor/wing/image plane. Comparisons between tiltrotor and helicopter rotor wake geometry measurements were made. Experimental wake geometry data were also compared with two wake models. Suggestions for improvements to existing prescribed-wake and free-wake models are proposed.