Abstract

This paper reviews counterflows, double counterflows, and circulation cells in vortex motion and argues that all these seemingly paradoxical phenomena can be caused by a common swirl-decay mechanism (SDM). It is shown that the SDM explains (a) the counterflow of water and oil in hydrocyclones, (b) the elongated counterflow of hot and cold air in vortex tubes, (c) the double counterflow occurring in vortex combustion chambers, and (d) the back flow in tubular chimneys of vortex units. The SDM also explains the development and disappearance of circulation cells, often referred to as vortex breakdown bubbles, in sealed cylindrical containers where the flow is driven by rotation of one end disk. The SDM also works in two-fluid flows modeling vortex bioreactors. In a few words, the SDM works as follows. Because of the balance of the centrifugal force and the radial gradient of pressure in a fast-swirling flow, the pressure at the rotation axis is smaller than that at the periphery. If the swirl decays downstream, the pressure grows along the axis. This axial gradient of pressure decelerates the near-axis flow and can reverse it, thus developing a local or global counterflow.

中文翻译：

---

在涡流运动中产生逆流和细胞的涡流衰减机制

摘要

本文回顾了涡流运动中的逆流、双逆流和循环单元，并认为所有这些看似矛盾的现象都可能是由一种常见的涡流衰减机制 (SDM) 引起的。结果表明，SDM 解释了 (a) 水力旋流器中水和油的逆流，(b) 涡流管中冷热空气的细长逆流，(c) 涡流燃烧室中发生的双逆流，以及 (d)涡流单元管状烟囱中的回流。SDM 还解释了循环细胞的发展和消失，通常称为涡流击穿气泡，在密封的圆柱形容器中，流动是由一端盘的旋转驱动的。SDM 也适用于模拟涡流生物反应器的双流体流动。简而言之，SDM 的工作原理如下。由于快速涡流中离心力和径向压力梯度的平衡，旋转轴处的压力小于外围的压力。如果漩涡向下游衰减，则压力沿轴增加。这种轴向压力梯度使近轴流减速并可以逆转它，从而形成局部或全局逆流。