Owl inspired material for trailing edge noise control | Research

Summary

Owls are known as silent predators of the night. Compared to other
famous raptors such as falcons and kestrels, owls are not fast at all.
Instead, after millions of evolution, owls have special adaptations which
enable them to approach to their prey with little noise. In particular,
owls’ feathers have three unique features: leading edge serrations,
trailing edge fringes, as well as the hairy dorsal surface. The function of
the last feature is not well understood, and no related application is
known.

The evolution in the past millions of years enables owls to reduce their flight noise efficiently, especially in the high-frequency range, where their preys are most sensitive.
Owls’ feathers have three unique features: leading edge serrations, trailing edge fringes, as well as the hairy dorsal surface.
In this research, artificial hairy structures are fabricated to resemble owls' downy feather. These structures are attached to a flat plate test model to study there effect on trailing edge noise.

The hairy coating can significantly reduce the high-frequency noise generated at the trailing edge. A theoretical model was developed to predict the noise radiation with the turbulence information obtained by the wake measurement using the hot-wire.

The microstructure of the velvet structure on an Eagle Owl's primary feather.

Setup of the acoustic measurement in the anechoic wind tunnel.

Comparison of the third-octave acoustic images of the clean and hairy flat plate models.

Reference

Peng Zhou, Siyang Zhong, Xin Zhang, On the effect of velvet structures on trailing edge noise: experimental investigation and theoretical analysis, Journal of Fluid Mechanics, vol. 919, A11, 2021