基于脱离速度的垂直气液两相管流流型识别

Identification of the vertical gas-liquid two-phase tube flow’s pattern based on the detachment velocity

流型是影响垂直气液两相管流流动与传热特性的主要因素,因而流型识别是两相流研究的首要任务。经典模型中,通过折算速度、表面张力和密度来耦合流型转换边界,通过试验数据,以折算速度为轴量,绘制出目前普遍接受的流型图。文中提出一种基于脱离速度大小来识别垂直气液两相管流流型的新方法。该方法的优点在于,以速度为参考标准,更有利于在压力、温度变化的环境中找到两相流运动的规律。文中深入分析了垂直气液两相管流的流动机理,以脱离速度来定义流型转换边界,区分垂直管中的4种常见流态,并与实测数据完全吻合,同时这种理论分析方法也对垂直气液两相管流中的举升效率、共流液体、临界状态和流型本质差别有着更为合理的解释。

Flow pattern is the main factor affecting the flow and heat-transfer characteristics of vertical gas-liquid two-phase pipe flow,so the identification of flow pattern is the primary task of the two-phase flow research.In the classic model,the flow pattern’s conversion boundary is coupled by the conversion velocity,surface tension and density,and the flow pattern diagram that is generally accepted currently is drawn based on the experimental data and with the conversion velocity as the axis.In this article,a new method is applied to identify the vertical gas-liquid two-phase pipe flow’s pattern based on the detachment velocity.The advantage is that with the velocity as the reference,it is more conducive to work out the law of two-phase flow movement in the environment of pressure and temperature changes.This article deeply explores the mechanism of the vertical gas-liquid twophase pipe flow,defines the flow pattern’s conversion boundary by separating the velocity,distinguishes the four common flow patterns in the vertical tube,and completely coincides with the measured data.In addition,this method of theoretical analysis gives a more reasonable explanation of essential difference in terms of lifting efficiency,co-flow liquid,critical state and flow pattern of the gas-liquid two-phase flow in a vertical tube.