A Multidisciplinary Experimental Study of Flapping Wing Aeroelasticity in Thrust Production

Abstract

This paper presents a multidisciplinary experimental endeavor in correlating flapping micro air vehicle (MAV) wing’s aeroelasticity and thrust production, by quantifying and comparing elasticity, dynamic responses and air flow patterns of six different pairs of MAV wings with varying elastic properties. This topic has been studied by experimental biologists on real insects and birds; other efforts have also been made to identify how enhanced wing structures of artificial flappers can enhance the lift and thrust. However in those previous studies, the wings may not be able to faithfully represent the physics behind hummingbird-size MAV flight. In this study, six pairs of MAV size wings (wing length 75 mm) of different reinforced structures are tested. After their static elastic properties and dynamic response characteristics are measured, each wing is mounted on a mechanism to perform single-degree-of-freedom flapping in both air and vacuum. A customized digital image correlation system measures the wing deformation, a load sensor attached to the flapping mechanism records the forces produced by the wings, and a stereo digital particle image velocimetry setup captures the flow structure around the wings. The data from all of these measurements are correlated in order to provide a thorough description of the numerous aeroelastic mechanisms needed for propulsive thrust generation. The study overcomes challenges in many aspects: measuring small magnitudes of complicated aerodynamic and inertial loads, describing flapping wing aeroelasticity through different techniques, obtaining rapid motion meas0urements from non-camera-friendly flexible membrane wing materials and post-processing the data for correlation. The results not only demonstrated how the current experimental techniques can be used in flapping wing MAV development, but also suggest a guideline for future flapping wing design methodologies. I.