FLIGHT OF VERY SMALL INSECTS
FLIGHT OF VERY SMALL INSECTS
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DOI：
10.1038/1781334a0
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发表时间：
1956-01-01
期刊：
影响因子：
64.8
通讯作者：
HORRIDGE, GA
中科院分区：
文献类型：
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作者：
HORRIDGE, GA
关于昆虫飞行的实验工作基本上证实了这样一种观点，即昆虫的翅膀在飞行中起着翼型的作用。然而，有可用的空气动力学结果表明，昆虫翅膀的尺寸存在一个下限，可以有效地作为一个翼型。虽然某些非常小的翅膀的结构表明了一种不同的飞行机制，但事实证明，这接近已知正常形状翅膀的观察极限。在非常低的速度下，对翼型的力的精确测量已经由Thom和Swart•完成。他们使用翼型RAF 6A，弦长1.24厘米，跨度7.5厘米，能够在油中测量到小于单位的雷诺数（在弦长上计算）。人们发现，在Re= 10以下，升力不再与给定入射角下速度的平方成正比，而是与自由流的速度成正比。同样，阻力系数在R= 10处开始增大，Re= 1时阻力系数大于10，而R= 100时阻力系数约为0·5。这些结果与昆虫飞行最相关的方面是阻力与升力的比率，根据他们的结果重新计算，这是在图1中绘制的不同雷诺数值。
EXPERIMENTAL work on the flight of insects has in general confirmed the view that the wing of an insect in flight acts as an aerofoil'. However, there are available aerodynamical results" which indicate the existence of a lower limit to the size of an insect wing which can act effectively as an aerofoil. This proves to be near the observed limit of known wings of normal shape, though the structure of certain very small wings indicates a different mechanism of flight.Accurate measurements of the forces on an aerofoil at very low speeds have been made by Thom and Swart•. Working with aerofoil RAF 6A, l· 24 cm. chord, 7· 5 cm. span, they were able to make measurements in oil down to Reynolds numbers less than unity (calculated on the chord). It was discovered that below Re= 10 the lift is no longer proportional to the square of the velocity for a given angle of incidence, but becomes proportional to the velocity of the free stream. Similarly, the drag coefficient begins to increase at R,= 10, and reaches a value greater than 10 for Re= 1, whereas it is about O· 5 for R= 100. The most relevant aspect of these results for insect flight is the ratio, recalculated from their results, of the drag forces to the lift forces, and this is plotted for various values of Reynolds numbering in Fig. I.