Experimental investigation of a biomimetic propeller coupled with owl-inspired leading and trailing edges serrations.

This article focuses on the development and evaluation of a bio-inspired coupled propeller (BCP) design for small unmanned aerial vehicles (UAVs), integrating both leading-edge (LE) and trailing-edge (TE) serrations inspired by owl feathers to reduce aerodynamic noise and improve performance. Experimental and numerical analyses demonstrate that the BCP achieves superior noise reduction—up to 3.1 dB in overall sound power level—and a 7.9% increase in thrust efficiency compared to baseline and single-structure serrated propellers. The LE serrations primarily suppress discrete tonal noise at blade passing frequencies, while TE serrations mainly reduce broadband noise above 2 kHz; their combination in the BCP yields synergistic passive flow control effects that modulate vortex formation, turbulence, and shedding, thereby enhancing aerodynamic efficiency and acoustic performance. Outdoor tests on a quad-rotor UAV confirm the BCP's noise mitigation capabilities, though the biomimetic designs incur increased power consumption due to added drag and weight. These findings provide insights into biomimetic noise reduction mechanisms and offer a foundation for optimizing quieter, more efficient UAV propulsion systems.