Noise Analysis of Insect-Scale Flapping Wing with Fluid Structure Interaction

In recent years, researchers have made significant progress in achieving high lift and large thrust in bio-inspired flapping-wing aircraft. However, there has been relatively less attention paid to the aerodynamic noise generated by flapping wings. Whether in military or civilian bio-inspired design, it is particularly important to design an efficient aircraft with the capability of quiet flight. This paper focuses on a bio-inspired flexible flapping wing as a research model and introduces acoustic-solid interaction modal and aerodynamic noise analysis methods to investigate it. Flexible wings with different material properties and flapping frequencies are calculated. In addition to analyzing the spatial distribution of noise, the instantaneous sound pressure curve is Fourier transformed, and different methods are used to analyze low-order and high-order harmonics of the flow-solid coupling calculation results. Finally, the equal loudness curve is introduced to consider the response of human ears to the noise. Using numerical simulations, we explore the positive effects of air vibration (sound) on the aerodynamic performance of flapping wings, investigate the influence of the wing's shape parameters, motion parameters, and flexible wing parameters on the sound field, and seek the inherent connection between the aerodynamic performance of flapping wings and air vibration, revealing the mechanism of aerodynamic noise generated by flapping wings. This study aims to answer questions such as how to improve the aerodynamic performance of flapping wings by utilizing air vibration through wing flexibility and how to achieve quiet flight through effective flapping motion, and hopes to provide some reference for the aerodynamic and quiet design of flapping-wing flight.