气液两相流垂直冲刷错列管束漩涡脱落特性的实验研究

Experimental Study of Vortex Shedding Characteristics of a Gas-liquid Two-phase Flow Vertically Sweeping Across a Staggered Tube Bundle

采用高速摄像仪拍摄的方法,对垂直上升的气液两相流体在矩形管道内冲刷节距比为1.0、1.5和2.0三种旋转正方形排列的错列管束漩涡脱落特性进行了研究。给出了在一个漩涡的形成与发展过程中,对周围气泡进行卷吸并在柱后形成气核的全过程;通过对漩涡脱落周期的统计,得出了在本实验范围内随含气率的增大漩涡脱落频率逐渐增大,漩涡脱落,St逐渐减小的结论;当含气率α=0.147时周期性漩涡脱落现象消失。

By adopting a method of high-speed video camera shooting,a study has been conducted of the vortex shedding characteristics of a staggered tube bundle,which is swept across by a vertically rising gas-liquid two-phase flow in a rectangular duct.The tube bundle has been arranged in three kinds of rotating square with a pitch ratio of 1.0,1.5 and 2.0 respectively.Shown are the whole process of entrainment of surrounding bubbles and the formation of a gas nucleus after a gas column during a vortex formation and development course.It has been concluded through a statistics survey of the vortex shedding cycles that with an increase of the void fraction within the range of the present experiment,the shedding frequency will gradually increase,leading to a shedding of the vortex,and the Strouha number assumes a gradual decrease.When the void fraction α=0.147,the phenomenon of a periodical vortex shedding will eventually disappear.