Aeroacoustic interaction between owl-inspired trailing-edge fringes and leading-edge serrations

Abstract

The silent flight achieved by owls is attributed to their unique wing morphologies, characterized by leading-edge (LE) serrations, trailing-edge (TE) fringes, and a velvet-like surface. The specific morphological effects of LE serrations and TE fringes on aeroacoustic performance have been widely studied, but the LE–TE aeroacoustic interaction remains poorly understood. This paper describes a simulation-based study of the aeroacoustic characteristics of owl-inspired TE fringes and their interplay with LE serrations by combining large-eddy simulations of unsteady near-field flow structures with the Ffowcs Williams–Hawkings equation for sound radiation. Using owl-inspired LE serrated and TE fringed wing models, it is verified that TE fringes enable a pronounced high-frequency sound reduction at angles of attack (AoAs) of 5–15° while achieving comparable aerodynamic performance to a clean model. The near-field vortex dynamics, pressure distributions, and velocity spectra reveal that TE fringes suppress flow separation and vortex shedding in the vicinity of the TE, consequently reducing local velocity fluctuations and far-field overall sound pressure levels. Furthermore, the combination of TE fringes and LE serrations enables a remarkable reduction in overall sound pressure levels at all AoAs, and their aeroacoustic interplay is responsible for stabilizing velocity fluctuations over the suction surface, which suppress both low- and high-frequency sound. Our results demonstrate that TE fringes are a robust sound reduction device in resolving the trade-off between aerodynamic force production and sound reduction, while LE serrations and TE fringes complement one another as an effective noise-reducing biomimetic design.