Published in the Institute of Physics journal, Bioinspiration and Biomimetics the research shows how the serrations on the leading edge of an owl’s wing are key to its stealthy, silent flight. A similar mechanism could be used, it is claimed, to develop mechanisms for noise suppression in wind turbines, aircraft, multi-rotor drones and other machines.
Lead author of the report Professor Hao Liu, from Chiba University, Japan, said: “Owls are known for silent flight, owing to their unique wing features, which are normally characterised by leading-edge serrations, trailing-edge fringes and velvet-like surfaces. We wanted to understand how these features affect aerodynamic force production and noise reduction, and whether they could be applied elsewhere.”
The researchers analysed owl-inspired feather wing models with and without leading edge serrations, by combining large-eddy simulations – a mathematical model for turbulence used in computational fluid dynamics to simulate air flows – and Particle-Image Velocimetry (PIV) and force measurements in a low-speed wind tunnel.
They discovered leading-edge serrations can passively control the transition between laminar, or streamline airflow, and turbulent air flow over the upper wing surface, at angles of attack (AoA) between zero and 20 degrees. This means they play a crucial role in aerodynamic force and sound production.
“These owl-inspired leading edge serrations, if applied to wind turbine blades, aircraft wings or drone rotors, could provide a useful biomimetic design for flow control and noise reduction,” said Professor Liu.
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