Flapping wing propulsion offers unrivaled maneuverability and efficiency at low flight speeds and in hover. These advantages are attributed to the leading edge vortex developing on an unsteady wing, which induces additional lift. We propose and validate a manipulation hypothesis that allows prolongation of the leading edge vortex growth phase, by delaying its detachment with the aid of flow control. This approach targets an overall lift increase on unsteady airfoils. A dielectric barrier discharge plasma actuator is successfully used to compress secondary structures upstream of the main vortex on a pitching and plunging flat plate. To determine flow control timing and location, the tangential velocity on the airfoil surface is used, which is also used to quantify topological effects of flow control. This flow control is then tested for different motion kinematics on a NACA 0012 airfoil. An increase of the peak circulation of the leading edge vortex of about 20% for all cases with flow control indicates that this approach is applicable for various kinematics, dynamics, and airfoil types.

中文翻译：

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通过在拓扑关键位置的等离子体流控制来延迟前缘涡旋分离

襟翼推进装置在低速飞行和悬停时提供了无与伦比的机动性和效率。这些优点归因于前缘涡旋在不稳固的机翼上形成，从而引起额外的升力。我们提出并验证了一种操纵假说，该假说通过延长流量控制的时间来使其脱离，从而延长了前沿涡流的生长阶段。这种方法的目标是增加非稳定翼型的整体升力。介电势垒放电等离子体致动器已成功用于压缩俯仰俯冲平板上主涡流上游的二级结构。为了确定流量控制的时间和位置，使用了机翼表面的切向速度，该速度也用于量化流量控制的拓扑效果。然后针对NACA 0012机翼上的不同运动运动学测试此流量控制。在所有带流量控制的情况下，前缘涡旋的峰值循环增加约20％，表明此方法适用于各种运动学，动力学和机翼类型。