Aerodynamics of a bio-inspired flexible flapping-wing micro air vehicle

Abstract

MAVs (micro air vehicles) with a maximal dimension of 15 cm and nominal flight speeds of around 10 m s⁻¹, operate in a Reynolds number regime of 10⁵ or lower, in which most natural flyers including insects, bats and birds fly. Furthermore, due to their light weight and low flight speed, the MAVs' flight characteristics are substantially affected by environmental factors such as wind gust. Like natural flyers, the wing structures of MAVs are often flexible and tend to deform during flight. Consequently, the aero/fluid and structural dynamics of these flyers are closely linked to each other, making the entire flight vehicle difficult to analyze. We have recently developed a hummingbird-inspired, flapping flexible wing MAV with a weight of 2.4-3.0 g and a wingspan of 10-12 cm. In this study, we carry out an integrated study of the flexible wing aerodynamics of this flapping MAV by combining an in-house computational fluid dynamic (CFD) method and wind tunnel experiments. A CFD model that has a realistic wing planform and can mimic realistic flexible wing kinematics is established, which provides a quantitative prediction of unsteady aerodynamics of the four-winged MAV in terms of vortex and wake structures and their relationship with aerodynamic force generation. Wind tunnel experiments further confirm the effectiveness of the clap and fling mechanism employed in this bio-inspired MAV as well as the importance of the wing flexibility in designing small flapping-wing MAVs.

Evolution of avian flight: muscles and constraints on performance

“…These include in vivo and in situ measures of the contractile behaviour of muscle [12 -14]: high-speed, three-dimensional videography that can reveal details of wing motion [15,16]; X-ray videography of skeletal kinematics [16,17]; particle image velocimetry and computational fluid dynamics to reveal aerodynamics [18 -20]. Research into the biomechanics of avian flight, to some extent, moved away from an ecomorphological and comparative to a phylogenetic emphasis during the past 20 years, in part because of excitement (and funding opportunities) linked to the bioinspired design of autonomous flying robots [21,22]. Thus, detailed information on muscle contractile behaviour in relation to flight performance is often available only for selected model species such as the pigeon (Columba livia), only in rare cases within clades of closely related species [23,24], and formal synthesis of new insights into the phylogeny of birds with the form and function of their muscular systems is not presently feasible.…”

Onboard/Offboard Sensor Fusion for High-Fidelity Flapping-Wing Robot Flight Data

“…eqs. [8][9][10][11][12][13][14][15][16][17][18][19] were found to converge in the static case, while during flight they vary to a limited extent, typically in conjunction with maneuvers. It can for instance be observed in fig.…”

“…While significant insight is now available on both fronts, thanks to studies on insects and birds [1,2,3,4], and, more recently, increasingly on robotic test platforms [5,6,7,8,9,10,11,12,13,14,15], the high complexity of flapping flight still poses a considerable challenge to FWMAV development. Additionally, it is still considerably difficult to obtain realistic experimental data, particularly in free flight and in different flight regimes.…”

Recent biomedical applications of bio-sourced materials

“…In recent years, various functional properties of dragonfly wings have gradually been reported by scholars all over the world, making it an important biological model of bionics [24][25][26][27][28][29].…”