Design of Revolutionary Ultra-Quiet Propulsors for S/VTOL

The overarching objective of the Phase-II effort is to build upon Harmony’s in-house developed conceptual design tools for S/VTOL (Short/Vertical Take-Off and Landing) propulsors (both propellers and rotors) and demonstrate their effectiveness by developing and testing a full-scale propulsor with low noise and high efficiency. Phase-I computational aeroacoustic analysis clearly demonstrated the ability to quiet VTOL propulsors (8X quieter than traditional VTOL propellers) with superior aerodynamic efficiency. While sub-scale experiments in an anechoic wind-tunnel with rapid-prototyped blades demonstrated similar reductions in interaction noise, aeroelastic effects (blade deflections and flutter instabilities) caused by the novel blade planform shape deteriorated thrust and produced excessive vibration. Therefore, a focus of Phase-II will be to couple an aeroelastic analysis with an improved aeroacoustic solver to produce a tool for the preliminary design and analysis of S/VTOL propulsors.  The design tool, once validated with sub-scale experiments, will be utilized to design an aeroacoustically tailored 8-ft diameter full-scale coaxial propulsor utilizing structurally stiff composite blades to minimize deflections and overall weight. The propulsor prototype will be built and its ability to generate the target thrust (1500 lbf) with a hover figure of merit (FM) > 0.7, propulsive efficiency (ηprop) > 0.85 and noise level < 80 dBA at 100 ft will be demonstrated via testing.