Three Dimensional Effects on the Translational Locomotion of a Passively Heaving Wing
Inspired by the novel flapping-wing mechanisms in nature flyers of insects, birds and bats, we have carried out a numerical study systematically investigating a three-dimensional flapping rigid wing with the passively actuated lateral and rotational motion. Distinguishing from the limited existing studies, our work performs a systematic examination on the effects of wing aspect ratio, inertia, torsional stiffness and pivot point on the dynamics response of a low aspect ratio rectangular wing under an initial zero speed flow field condition.
Figure 1. Evolution of symmetry breakdown (σ=8.0, Refr=80, F=2.0, AR=∞). Upper: Instantaneous Reu and θ; Lower: Evolution process.
Marine animal wings and foils perform remarkable swimming abilities by creating high thrust speed and flexible maneuverability. This research on the investigation of propulsion mechanisms of flapping wings is both of interest to the MAV community and of importance to comparative morphologists when they are considering how physics constrains biological design. The assessment tool can also be used to predict the performance of various bio-inspired marine applications.
Figure 2. Vortex topology (Q contour) for 3D wing at different plunging frequency ratio, with magnitude of iso-surfaces as 0.0002 ((σ=8.0, h=0.5, Refr=80 and AR=2.0)). (a) F=3.0. (b) F=8.0.
The simulation results show that the symmetry break-down of the flapping wing results in a forward/backward motion with a rotational pitching, as shown in Figure 1. Depending on various kinematic and dynamic system parameters, the lateral induced velocity shows a number of different hydrodynamic performances, for example, wing under faster plunging frequencies develop a wake structure with a smaller vortex angle (Figure 2), which can slow down the energy dissipation, therefore the wing is able achieve a faster forward speed.
For more information about the project contact Dr Qing Xiao (firstname.lastname@example.org), Lecturer at the Department of Naval Architecture and Marine Engineering at the University of Strathclyde.
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