Acoustic perception of bio-inspired unmanned aerial vehicle propellers

While bio-inspired blade modifications have been extensively investigated for aerodynamic performance enhancement, their influence on the flow mechanisms governing noise generation and perceived acoustic comfort remains insufficiently understood. This study integrates aeroacoustic and psychoacoustic analyses to evaluate the effects of leading-edge (LE), trailing-edge serrations (TE), and boundary-layer (BL) modifications on a small unmanned aerial vehicle (UAV) propeller in hover. The flow field was resolved using a sliding-mesh delayed detached eddy Simulation framework based on the shear stress transport k–ω model, while far-field acoustics were predicted using the Ffowcs Williams–Hawkings analogy. The results indicate that individual bio-inspired modifications introduce acoustic tradeoffs, whereby reductions in tonal noise may be accompanied by increased broadband emissions within the 1–5 kHz frequency range most relevant to human hearing. Specifically, LE modification promotes broadband amplification through increased radial-flow-induced unsteadiness, whereas the BL treatment increases high-frequency content through enhanced turbulent activity near the blade surface. In contrast, the combined TE+BL configuration shows the best acoustic performance. The interaction between trailing-edge serrations and boundary-layer trips reduces the persistence of large-scale coherent wake structures, leading to lower broadband noise levels and improved spectral characteristics. Quantitatively, the TE+BL configuration achieves an approximately 10 dB reduction at the fundamental blade-passing frequency relative to the baseline propeller. Psychoacoustic analysis further demonstrates concurrent reductions in loudness and sharpness, resulting in improved acoustic comfort. The findings highlight that effective UAV propeller noise mitigation requires controlling spectral distribution and high-frequency broadband content beyond reducing overall sound pressure level, demonstrating the value of integrating psychoacoustic considerations into propeller assessment.