Rotor Noise Reduction Using Beveled Trailing Edges and Hybrid RANS/LES Simulations

This study investigates the influence of suction-side trailing-edge beveling on the aerodynamic performance and aeroacoustic characteristics of a small-scale ideally twisted rotor in hover. High-fidelity hybrid RANS/LES simulations using OVERFLOW, combined with PSU-WOPWOP and UCD-QuietFly acoustic predictions, are performed for a baseline blunt trailing edge and two beveled geometries (SS2 and SS4). The results show that beveling increases the effective camber near the trailing edge, thereby improving thrust and increasing overall figure of merit by up to 6.52\% for the steepest bevel. A central focus of the study is the mitigation of high-frequency trailing-edge vortex-shedding (TE-VS) noise, previously identified as a dominant source of high-frequency tonal radiation in small-scale AAM rotors. Instantaneous pressure fluctuation contours and spanwise distributions of upwash fluctuations reveal that amplified TE-VS structures are weakened for the SS2 case and eliminated for the SS4 case. Secondary vortex development and associated mid-frequency blade secondary vortex interaction noise are also modified by beveling, with notable reductions in 5--10 kHz content. Overall, suction-side beveling provides an effective and practical geometric modification that simultaneously enhances aerodynamic performance and suppresses aerodynamic noise, offering a promising design strategy for efficient and quiet AAM rotor systems.