Computational Modelling of a Distributed Propulsion System Using CABARET Method on Rotating Meshes: a Parametric Study and Analysis of the Geometry Effects

Urban Air Mobility (UAM) vehicles require distributed propulsion (DP) systems that are both aerodynamically efficient and quiet, yet the close arrangement of multiple propellers presents significant noise and performance challenges. This study presents a comprehensive parametric analysis of a three-propeller DP configuration using high-fidelity Large Eddy Simulation (LES) with the CABARET method on rotating meshes. The effects of trailing-edge serrations, central rotor axial displacement, and inter-rotor phase angle variation were evaluated. Results show that sawtooth-patterned trailing-edge serrations consistently reduce band-limited overall sound pressure level (BL OASPL) by up to 2.4 dB, with maximum noise mitigation when the central rotor is positioned closer to the wing at a 90 degree difference. While serrations introduce a minor aerodynamic penalty, positioning rotor closer to the wing increases thrust coefficient by approximately 7.8%, attributed to enhanced rotor-wing interaction. Flow analysis reveals that serrations disrupt coherent trailing-edge vortices, reducing acoustic emissions. These findings highlight the potential of combined geometric and phase optimization for quieter, more efficient DP systems in UAM applications.