THE AERODYNAMICS OF PLUMED SEEDS
THE AERODYNAMICS OF PLUMED SEEDS
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DOI：
10.2307/2389661
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发表时间：
1990-01-01
影响因子：
5.2
通讯作者：
JOHNSON, EA
中科院分区：
文献类型：
--
作者：
GREENE, DF;JOHNSON, EA
本文以菊科植物和芦笋属植物（Asclepias syriaca， L.）为研究对象，对羽状种子的空气动力学进行了研究。(家庭萝摩科)。组成种子羽流的毛被模拟成一个单一的长圆柱体，经历与静止空气中测量的终端速度相当的环境风速。面积的相关测量是羽流的总项目面积，而不是假想的“圆盘”的规划面积，其中的毛发驻留。气流实验表明，阿斯克勒庇亚斯的毛发在0.5到0.9 ms-1左右的风速下开始明显弯曲，迎角几乎达到90度。风速为4.0至5.1 ms-1。因此，当人为地增加试样的质量时，终端速度呈强烈的曲线增长。不对称翅果和羽状种子在降低下降速度方面的“效率”差不多，当质量与投射面积的比率很高时。然而，在质量与投射面积的比例较低时，羽状设计在降低下降速度方面更“有效”。
The aerodynamics of plumed seeds are examined using four species of Compositae and Asclepias syriaca (L.) (family Asclepiadaceae). The hairs comprising the plume of the seeds are modelled as a single long cylinder experiencing an ambient wind velocity equivalent to the measured terminal velocity in still air. The relevant measure of area is the total project area of the plume rather than the plan area of the imaginary ''disk'' in which the hairs reside. Experiments with an air stream show that the hairs of Asclepias begin to bend significantly at a wind speed of around 0.5 to 0.9 ms-1, and have an angle of attack of almost 90.degree. at wind speeds of 4.0 to 5.1 ms-1. Consequently, there is a strongly curvilinear increase in terminal velocity as mass is artificially added to specimens. Asymmetric samaras and plumed seeds are about equally ''efficient'' at reducing descent velocity when the ratio of mass to projected area is high. At lower ratios of mass to projected area, however, the plumed design is more ''efficient'' at reducing descent velocity.