首页> 外文会议>41st AIAA fluid dynamics conference and exhibit 2011 >A Self-Excited Flapping Wing: Lift, Drag and the Implications for Biological Flight
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A Self-Excited Flapping Wing: Lift, Drag and the Implications for Biological Flight

机译:自振扑翼:升力,阻力及其对生物飞行的影响

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More than 50 million years ago bats evolved from a gliding-fluttering flight to power flapping. The conditions or reasons that led from gliding to power flight are still unknown. In this work we explore 'passive' flight (no actuation of the wing) and the transition between fixed wing gliding and passive flapping using a simple two degree of freedom wing model. The physical model is a flat plate with a hinged trailing flap. The wing body is cantilevered with a well-defined natural frequency. The wing model was tested in wind tunnel with a Reynolds number of approximately 45,000. At low wind speed the wing is stationary, but a critical speed the wing starts to flap. In a series of experiments we measured the lift and drag forces, and the wing kinematics as we varied the natural frequency of the wing, the angle of attack and the wind speed. We present the force and kinematics measurements. Our results show that there is a considerable increase in the lift coefficient (between 25% to 16%) when the wing starts to oscillate, when compared to the non-oscillating wing. Finally, we hypothesize that early bats may have used a similar gliding-fluttering transition to increase lift generation and this passive motion eventually led to powered flight.
机译:超过五千万年前,蝙蝠从滑翔的飞行演变为动力扑打。从滑行到动力飞行的条件或原因仍然未知。在这项工作中,我们使用简单的两自由度机翼模型探索“被动”飞行(不驱动机翼)以及固定机翼滑行和被动襟翼之间的过渡。物理模型是带有铰链式尾翼的平板。机翼悬臂具有明确的固有频率。机翼模型在雷诺数约为45,000的风洞中进行了测试。在低风速下,机翼静止不动,但在临界速度下,机翼开始拍打。在一系列实验中,当我们改变机翼的固有频率,迎角和风速时,我们测量了升力和阻力以及机翼运动学。我们介绍了力和运动学测量。我们的结果表明,与非摆动式机翼相比,当机翼开始摆动时,升力系数显着提高(25%至16%之间)。最后,我们假设早期的蝙蝠可能使用了类似的滑行颤动过渡来增加升力产生,并且这种被动运动最终导致了动力飞行。

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