Author: Wei, Chong
Title: Effects of owl-inspired leading-edge serrations on sound suppression and aerodynamic performance
Advisors: Tang, Hui (ME)
Degree: M.Sc.
Year: 2019
Subject: Hong Kong Polytechnic University -- Dissertations
Aerodynamic noise
Airplanes -- Performance
Airplanes -- Design and construction
Department: Faculty of Engineering
Pages: xvii, 88 pages : color illustrations
Language: English
Abstract: It is well known that owls are famous for silent flight. They can achieve obviously low noise in gliding and flapping flights owing to their unique wing morphologies, which are normally characterized by leading-edge serrations, trailing-edge fringes and velvet-like surfaces. However it is still not fully understood that how the morphological characteristics correlate with the aerodynamic and aeroacoustic mechanisms. An experimental investigation has been conducted to study the morphological effects of leading-edge serrations on aerodynamic performance and noise reduction by testing clean and serrated owl-inspired single-feather blades in wind tunnels. Forces acting on blades were measured by a six-component load cell. PIV system was used to detect near-field flow structures around the blade. Microphone was set to measure sound pressure level around the blade. A better understanding in the underlying physics of how the leading-edge serrations reduce noise and affect aerodynamic forces has been achieved. The leading-edge serrations may be a useful device for aero-acoustic control in biomimetic rotor designs for propellers, wind turbines, multi-rotor drones and other turbomachinery. It was found that the leading-edge serrations are capable of providing a strategy in resolving the tradeoff between sound suppression and force production. Comparing to the clean single-feather wing model, the serrated wing model shows a reduction in aerodynamic force production at lower AoAs < 15° but obviously a capability to achieve an even aerodynamic performance at higher AoAs > 15° while significantly suppressing the aerodynamic noise production. And the denser or longer of the serrations, the poorer aerodynamic performance and the better noise suppression can serrated blades get.
Rights: All rights reserved
Access: restricted access

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