Dynamics and Aeroelasticity of Hover-Capable Flapping Wings: Experiments and Analysis

Abstract

This dissertation addresses the aerodynamics of insect-based, bio-inspired, flapping wings in hover. An experimental apparatus, with a bio-inspired flapping mechanism, was used to measure the thrust generated for a number of wing designs. Bio-Inspired flapping-pitching mechanisms reported in literature, usually operate in oil or water at very low flapping frequencies (~0.17 Hz). In contrast, the mechanism used in this study operates in air, at relatively high frequencies (~12 Hz). All the wings tested showed a decrease in thrust at high frequencies. A novel mechanism with passive pitching of the wing, caused by aeroelastic forces, was also tested. Flow visualization images, which show the salient features of the airflow, were also acquired. At high flapping frequencies, the light-weight and highly flexible wings used in this study exhibited significant aeroelastic effects. For this reason, an aeroelastic analysis for hover-capable, bio-inspired flapping wings was developed. A finite element based structural analysis of the wing was used, alongwith an unsteady aerodynamic analysis based on indicial functions. The analysis was validated with experimental data available in literature, and also with experimental tests conducted on the bio-inspired flapping-pitching mechanism. Results for both elastic and rigid wing analyses were compared with the thrust measured on the bio-inspired flapping-pitching mechanism.