The dynamics of shock accelerated light and heavy gas cylinders
The dynamics of shock accelerated light and heavy gas cylinders
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DOI：
10.1063/1.858562
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发表时间：
1993-09
影响因子：
4.6
通讯作者：
J. Jacobs
中科院分区：
文献类型：
--
作者：
J. Jacobs
人们已经做过这样的实验：一个圆柱形体积的气体，它比周围的气体轻或重，被一个微弱的冲击波脉冲加速。氦气或六氟化硫（SF6）的层流射流用于产生圆柱体，平面激光诱导荧光用于可视化流动。结果发现，通过与冲击波的相互作用，沉积在SF6圆柱体的边界上的涡量从重气体分离，形成一对涡，该涡随后将SF6缠绕在它们周围。这一过程与轻气体实验中观察到的情况大不相同，轻气体实验表明，少量的氦留在涡度中，最终成为涡核的一部分。离心力结合在两种气体中的涡度的扩散率的差异给出这些差异的可能原因。测量的初始下游速度的重气体圆柱被发现符合理论。
Experiments have been carried out in which a cylindrical volume of a gas, that is either lighter or heavier than its surroundings, is impulsively accelerated by a weak shock wave. Laminar jets of helium or sulphur hexafluoride (SF6) are used to produce the cylinders, and planar laser‐induced fluorescence is used to visualize the flow. It is found that the vorticity deposited on the boundary of the SF6 cylinder by the interaction with the shock wave, separates from the heavy gas to form a pair of vortices, which subsequently wrap the SF6 around them. This process is quite different from what is observed in the light gas experiments, which showed a small amount of helium to remain with the vorticity, eventually becoming part of the vortex cores. Centrifugal forces combined with differences in the rates of the diffusion of vorticity in the two gases are given as possible reasons for these differences. Measurement of the initial downstream velocity for a heavy gas cylinder is found to agree well with a theory...