Aeroacoustic investigation of owl-inspired hybrid trailing-edge serrations

Owls exhibit remarkably silent flight, largely attributed to trailing-edge (TE) serrations on their wings. Inspired by this biological adaptation, TE serrations have become promising passive-noise-control strategies for aerodynamic devices, including drones and wind turbines. However, conventional designs typically feature single-scale geometries—Such as sawtooth or sinusoidal serrations—that fail to replicate the owl’s inherently dual-scale morphology: Macro-scale waviness formed by feather tips combined with micro-scale morphology. Here, we introduce and evaluate a hybrid TE serration design that incorporates both macro-scale wave patterns and micro-scale fringe-like elements to closely emulate the owl wing structure. Using large-eddy simulations coupled with the Ffowcs Williams-Hawkings acoustic analogy, we assess three configurations: A smooth baseline, a conventional wavy serration, and the proposed hybrid serration. Our results indicate that the hybrid configuration achieves an overall noise reduction of about 12 dB relative to the smooth baseline, surpassing the conventional wavy configuration by approximately 2.5 dB, while preserving aerodynamic performance as measured by lift-to-drag ratio. Flow-field analyses further reveal that dual-scale serrations effectively suppress TE pressure fluctuations, highlighting a key aeroacoustic advantage of the owl-inspired hybrid approach. These insights advance our understanding of bioinspired noise-control mechanisms and provide practical guidelines for designing quieter aerodynamic systems.