Study of Propeller Noise Under Edgewise and Transition Flight Conditions for Urban Air Mobility

This study investigates the aerodynamic and acoustic characteristics of a five-bladed propeller operating under edgewise and transition conditions using a hybrid LES–URANS (DDES) approach coupled with the impermeable Ffowcs–Williams Hawkings acoustic analogy. Numerical predictions of propeller performance and noise were validated against experimental data from Virginia Tech, demonstrating good agreement in thrust, torque, and acoustic spectra. Flow-field analyses reveal that edgewise inflow induces significantly stronger blade–vortex interactions than transition flight, driven by intensified tip-vortex impingement and leading-edge vortex shedding. Surface-pressure fluctuation analysis shows that the highest unsteady loading occurs near 0.8Rp, where tip vortices strike the following blade; the edgewise condition exhibits elevated leading edge fluctuations, indicating higher BVI and BWI noise generation. Additional high-frequency fluctuations near the trailing edge and blade tip suggest enhanced trailing edge and tip vortex formation noise under edgewise operation. Far-field acoustic results confirm these mechanisms, with the edgewise condition producing higher first-BPF tonal levels and increased broadband noise between the first and third BPFs across all observer locations, consistent with stronger BVI and BWI noise. Overall, the findings demonstrate that edgewise inflow substantially amplifies both tonal and broadband noise.