Noise Generation of Propellers in Edgewise Flight with Turbulent Wake Ingestion

This study examines the aerodynamic and aeroacoustic behavior of a propeller-wake interaction setup, consisting of an upstream circular cylinder and a propeller operating in edgewise flight conditions. Far-field noise data were collected and analyzed for the propeller under both laminar inflow and wake-ingesting conditions. At lower inflow velocities, the aerodynamic forces showed minimal variation when the cylinder wake was ingested. However, as the inflow velocity increased, notable changes in aerodynamic performance were observed. Additionally, the overall sound pressure level and its directivity were influenced by the wake ingestion. Noise analysis revealed distinct differences in the sound pressure level spectra when the propeller ingested the cylinder wake, characterized by a complex "haystacking" pattern in the blade passing frequency and its harmonics. New tonal components emerged near the blade passing frequency and its harmonics, likely attributed to interactions between the blade motion and periodic vortex shedding in the incoming wake of the cylinder. The findings of this study contribute to a better understanding of the noise generation mechanisms of rotors interacting with periodic wake structures, such as those produced by upstream vehicle components or environmental gusts.