Research on the aerodynamic performance and noise reduction design of small unmanned aerial vehicles based on noise source localization

This study addresses aerodynamic noise control in small Unmanned Aerial Vehicles (UAVs) by proposing a noise-reduction method based on noise source localization. The flow field is obtained using Large Eddy Simulation (LES), and noise propagation is predicted via the Ffowcs Williams–Hawkings (FW-H) acoustic analogy equation. Aerodynamic noise is then solved using the Hybrid Computational Aeroacoustics (HCAA) method. The synergistic effects of rotational speed and freestream velocity on the rotor flow field and noise are systematically analyzed. Based on noise source distribution characteristics, a novel structure is proposed, consisting of ridge-shaped grooves at 30% chord on the rotor’s upper surface leading edge to divide large-scale separation vortices, and conical protrusions on the blade tip trailing edge to guide vortex separation paths. Numerical results show that the ridge-shaped grooves reduce the peak time-averaged fluctuating acoustic pressure on the upper surface by 50% and attenuate mid-to-high-frequency far-field noise by 6 dB. The conical protrusions reduce the concentrated noise source area at the blade tip by 70%. The optimized design lowers the maximum overall sound pressure level by 3.56 dB at 10 times the radius laterally, with under 1% aerodynamic loss compared to the original model. This study demonstrates that local structural modification based on noise source localization offers an effective pathway for low-noise design of small UAVs.