Aerodynamics of a Flapping and Pitching Wing Using Simulations and Experiments

Computational fluid dynamics simulation results for a thin cambered plate airfoil, and flow visualization and force measurements from experiments conducted in water on a flapping-and-pitching thin flat-plate wing of semi-elliptic planform at low Reynolds numbers are reported. Time-varying force data, measured using a force transducer, provide a means to understand the mechanisms that lead to enhanced performance observed in insect flight compared with fixed-wing aerodynamics. Experimental uncertainties associated with low-level (∼1 N) fluid dynamic force measurements on flapping-and-pitching wings, including inertia effects, are addressed. A previously proposed pitching mode in which the leading-edge and trailing-edge switch roles to allow using cambered airfoils is shown to be feasible. A vortex-trapping model is proposed to explain the aerodynamic advantages of switching. The present results also support the authors' proposed idea that an optimum reduced flapping frequency might exist. The study has applications in micro air vehicle development.

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