Proceedings ArticleDOI
An Experimental Investigation on the Asymmetric Wake of an Oscillating Airfoil
TLDR
In this article, wake formation behind a sinusoidally piching NACA 0012 has been studied with PIV measurements, and the evolution of wake structures with increasing Strouhal number was reproduced successfully.Abstract:
Bio-inspired aerodynamic designs have been mutually promoted by the studies on flapping wings in the past decades. Among the tons of researches topics, the wake formation/structure of an oscillating airfoil is more attractive, and it results in the development of both numerical methods and flow diagnostics techniques. In this paper, wake formation behind a sinusoidally piching NACA 0012 has been studied with PIV measurements. The evolution of wake structures with increasing Strouhal number was reproduced successfully. With further experiments, the effect of Strouhal number, the amplitude and mean value of AOA on the asymmetric wake formation were also investigated. Results showed that the distance between vortex street became larger with increasing amplitude, while mean strength of vortices declined. Besides, the asymmetric wake formation was strongly dependent on the mean. Specifically, based on our experiments, the direction of wake asymmetry was changed at a and .read more
Citations
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Journal ArticleDOI
A review on fluid dynamics of flapping foils
Wu Xia,Wu Xia,Xiantao Zhang,Xiantao Zhang,Xinliang Tian,Xinliang Tian,Xin Li,Xin Li,Wenyue Lu,Wenyue Lu +9 more
TL;DR: The fluid dynamics of flapping foils are reviewed in this paper, where a wide range of researches are conducted for the two-dimensional flapping foil which has a relatively simple geometry, however, for a three-dimensional foil, the aspect ratio and shape take effects and completely distinct fluid dynamics are revealed compared with the 2D one.
References
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Journal ArticleDOI
Oscillating foils of high propulsive efficiency
TL;DR: In this article, the phase angle between transverse oscillation and angular motion is the critical parameter affecting the interaction of leading-edge and trailing-edge vorticity, as well as the efficiency of propulsion.
Journal ArticleDOI
Vortical patterns in the wake of an oscillating airfoil
TL;DR: In this article, the vortical flow patterns in the wake of a NACA 0012 airfoil pitching at small amplitudes were studied in a low speed water channel, and it was shown that a great deal of control can be exercised on the structure of the wake by the control of the frequency, amplitude and also the shape of the oscillation waveform.
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Dissecting insect flight
TL;DR: The results obtained by “taking the insects apart” helped to resolve previous puzzles about the force estimates in hovering insects, to ellucidate basic mechanisms essential to flapping flight, and to gain insights about the efficieny of flight.
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Flapping Wing Aerodynamics: Progress and Challenges
TL;DR: In this article, a review of recent developments in the understanding and prediction of flapping-wing aerodynamics is presented, with a special emphasis on the dependence of thrust, lift, and propulsive efficiency on flapping mode, amplitude, frequency, and wing shape.
Journal ArticleDOI
Vortex shedding and frequency selection in flapping flight
TL;DR: In this article, the authors investigated the time scales associated with the shedding of the trailing and leading edge vortices, as well as the corresponding time-dependent forces, and presented a generic mechanism of the frequency selection as a result of unsteady aerodynamics.
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