Effects of wing flexibility on sound characteristics of a four-wing flapping wing micro air vehicle

Abstract

The objective of this study was to understand the sound generation of flapping wings. In particular, the structural properties of the wings were varied to assess the effects of wing flexibility on the sound generation of flapping wings. A four-wing, hummingbird-inspired flapping wing micro air vehicle (FMAV) was considered. The half wing span was approximately six centimeters and the flapping frequency was approximately 25 Hz. The sound produced by the FMAV was measured using a 1/2 inches diameter microphone in an acoustic chamber under the quiescent flow condition. Time-averaged aerodynamic forces were measured by the force and torque sensor Nano17 (ATI Industrial Automation). Results revealed the characteristics of flapping-wing sound in terms of directivity, frequency response, and attenuation. Moreover, the degree of wing deformation led to a variation in the frequency response corresponding to the maximum sound pressure level as well as time-averaged aerodynamic force, even when the flapping frequenc...