Efficiency of lift production in flapping and gliding flight of swifts.
Efficiency of lift production in flapping and gliding flight of swifts.
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DOI：
10.1371/journal.pone.0090170
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Bomphrey RJ
中科院分区：
文献类型：
--
作者：
Henningsson P;Hedenström A;Bomphrey RJ
许多飞行动物将扑翼和滑翔飞行作为其日常行为的一部分。这两种运动模式对机翼设计的空气动力效率提出了相互冲突的要求，并且在没有极端变形的情况下，机翼无法针对两种飞行模式进行优化。在滑翔飞行中，机翼经历均匀的入射流，最佳形状是具有椭圆平面形状的高展弦比机翼。另一方面，在扑翼飞行中，翼尖的运动速度比根部快，从而产生翼展方向的速度梯度。为了补偿，最佳机翼形状应朝尖端逐渐变细（减少局部弦）和/或从根部到尖端扭转（减少局部攻角）。我们假设，如果一只鸟改变翅膀和调整翅膀形状以适应两种飞行模式的能力有限，那么预计会优先选择扑动飞行优化，因为这是对能量要求最高的飞行模式。我们通过研究一种著名的扑翼滑翔物种（常见的雨燕）来测试这一点，方法是测量两只鸟（一只在滑翔，一只在风洞中扑动飞行）产生的尾流。我们计算了翼展效率，即升力产生的效率，发现扑翼雨燕的翼展效率始终高于滑翔雨燕。这支持了我们的假设，并表明尽管雨燕之前已被证明在滑翔时会大幅增加其升阻比，但机翼形态经过调整，可以在扑动时产生升力方面更具空气动力学效率。由于可以假设扑动和滑翔的身体阻力相似，因此扑动飞行中与滑翔飞行相比更高的总阻力主要是由于扑动运动导致机翼轮廓阻力增加的结果，超过了诱导阻力的减少。
Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord) and/or twist from root to tip (reducing local angle of attack). We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding species, the common swift, by measuring the wakes generated by two birds, one in gliding and one in flapping flight in a wind tunnel. We calculated span efficiency, the efficiency of lift production, and found that the flapping swift had consistently higher span efficiency than the gliding swift. This supports our hypothesis and suggests that even though swifts have been shown previously to increase their lift-to-drag ratio substantially when gliding, the wing morphology is tuned to be more aerodynamically efficient in generating lift during flapping. Since body drag can be assumed to be similar for both flapping and gliding, it follows that the higher total drag in flapping flight compared with gliding flight is primarily a consequence of an increase in wing profile drag due to the flapping motion, exceeding the reduction in induced drag.
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影响因子：
56.9
作者：
Videler, JJ;Stamhuis, EJ;Povel, GDE
通讯作者：
Povel, GDE
影响因子：
3.9
作者：
Henningsson, P.;Muijres, F. T.;Hedenstrom, A.
通讯作者：
Hedenstrom, A.
影响因子：
3.9
作者：
Bomphrey, Richard J.;Henningsson, Per;Hollis, David
通讯作者：
Hollis, David
影响因子：
2.8
作者：
Henningsson, P.;Hedenstrom, A.
通讯作者：
Hedenstrom, A.
DOI：
10.1098/rstb.1993.0079
发表时间：
1993-06-29
期刊：
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES
影响因子：
--
作者：
THOMAS, ALR
通讯作者：
THOMAS, ALR