Acoustics of a Rotary Wing with Passive Reduced Tip Vortex in a Static Configuration

Acoustics data collection was performed in an anechoic chamber for two propeller blade types, one a power optimized blade and one a novel blade designed to reduce generated tip vortex strength. Both blade types had a 7.82” radius, a 2.25” root chord, a taper ratio of 2, a thrust coefficient of 0.003, and used an Eppler E387 airfoil. The blades were held at a steady 5000 rotations per minute as data were captured at 11 different microphone locations downwind of the rotor disc. Data were processed using a Fourier transform and analyzed. Key peaks in the processed data were identified and compared for each blade type and microphone location. Compared to the power optimized blade, the wake-optimized blade was found to have a greater number of distinct peaks. Additionally, for peaks that were present in the acoustic signatures of both blade types, the wake-optimized blade’s peaks were slightly greater in magnitude on average.