Abstract
Dragonfly wings have many excellent functions, such as superhydrophobic, fatigue resistance, anti-reflection, etc. However, there are few reports on the low noise flight of dragonfly wings. For this reason, the microgeometry of dragonfly wings was studied in this paper to reveal the mechanism of low-noise flight of dragonfly leading veins. The micromorphology of dragonfly wings was observed by scanning electron microscopy. It was found that the leading-edge veins of dragonfly wings have a triangular prism-like serrated structure, which has been proven to have the effect of improving aeroacoustics. According to the principle of scale law of flying organisms, a bionic model with the leading-edge microstructure of dragonfly’s front wing was established, and computational fluid dynamics (CFD) analysis of serration bionic microstructure was carried out. The effects of geometric parameters, such as height, width and overall amplification factor of microstructure on aeroacoustics were obtained. The distribution of pressure fluctuation on the surface of the bionic wing was also analyzed in this paper. It was found that the serrated microstructure can significantly suppress the noise generation in the mid-frequency band. Finally, wind tunnel tests were simulated using a designed low-noise rotating test platform. The test results confirmed that the serration microstructure has certain noise-reduction characteristics.
Highlights
The dragonfly has been attracting much interest due to its excellent characteristics, such as low-noise high mobility flight [1]
The study in anti-vibration and noisereduction characteristics of dragonfly wings mainly focused on the pterostigma of dragonfly wings, and the low-noise flight characteristics of dragonfly wings are rarely reported in detail
Wind tunnel tests confirmed that the trailing edge noise dominated when the incident airflow was laminar and that the leading edge noise became the main source of noise and concealed the trailing edge noise when the incident airflow was severe turbulence [3]
Summary
The dragonfly has been attracting much interest due to its excellent characteristics, such as low-noise high mobility flight [1]. The height of the serrated leading edge is an important parameter affecting the noise-reduction effect of the flat wing [7]. This paper mainly studies the morphology of dragonfly wing leading edge and its noise-reduction mechanism and establishes a bionic model. The noise-reduction characteristics of the dragonfly wing microstructure are summarized and analyzed.
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