City Research Online

Abstract

Owls have evolved unique wing features that enable silent flight, a crucial adaptation for their nocturnal hunting strategy. This study investigates the role of leading edge combs, also known as serrations or barbs, in reducing noise emissions and enhancing aerodynamic performance. Previous research has demonstrated the positive effects of serrations on both noise suppression and aerodynamic efficiency on rectangular wings. However, the aerodynamic mechanism by which serrations contribute to noise suppression on swept wings remains unexplored. We speculate herein that this is specifically affecting the tip vortex noise at varying angles of attack, inspired from animal studies with removed serrations. Experiments using particle image velocimetry (PIV) and flow visualization techniques are employed and show the flow turning induced by serrations and its subsequent effect on tip vortex formation, which results in lower vortex strength and core size, linked towards reduced vortex-induced noise emission. The results demonstrate the passive and three-dimensional flow control dependent on inflow conditions and offer an insight into the mechanism by which serrations contribute to silent flight, particularly during the final stages of hunting. It is also suggested that the serrations work in similar fashion to other swept wing flow control devices in attenuating the spanwise velocity component and increasing stall AoA.

Publication Type:	Conference or Workshop Item (Paper)
Additional Information:	© AIAA 2024.
Subjects:	Q Science > QL Zoology T Technology > TL Motor vehicles. Aeronautics. Astronautics
Departments:	School of Science & Technology School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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