竖直较大管径内气液两相流截面含气率实验研究

截面含气率是气液两相流动过程中的关键参数之一.在大管径流道内的气液两相流,弹状流难以形成,与常规通道相比,其流型特征明显不同.适用于常规通道截面含气率的一般计算方法,对于大管径流道而言,其适用性也较差.本文通过研究较大直径圆管内的气液两相流动过程,寻找适合于过渡尺寸流道内两相流动截面含气率的计算方法,从而建立起完整的、针对各个尺度范围内截面含气率的计算方法.实验选圆管直径为50 mm,介于常规通道和大通道之间；以空气和水作为工质,气相、液相折算速度的范围分别为0.05-2.0 m/s及0.01-2.0 m/s.首先利用获得的截面含气率实验数据,对适用于常规通道和大通道的截面含气率计算模型进行了评价；然后通过分析几类漂移流模型计算方法的分布系数和漂移速度的变化规律,解释了Hibiki-Ishii、Kataoka-Ishii、Kawanishi等几个模型计算误差较大的原因.

Study on void fraction of vertical gas-liquid two-phase flow in a relatively large diameter pipe

Void fraction is one of the key parameters in gas-liquid two-phase flow.In pipes with large diameters,slug flow is difficult to exist,and the characteristics of two-phase flow in large channels are significantly different from that in small pipes.The general methods for calculating void fraction in conventional channels are poorly applicable.The paper is aimed to seeking an appropriate method for calculating void fraction of two-phase flow in relatively large tubes with the help of experimental research,and establishing a uniform method covering different channel sizes.The diameter of the tube for experiments is 50 mm, which is between conventional and large size channels,and the working fluids are air and water.Superficial gas and liquid velocities are in the ranges of 0.05-2.0 m/s and of 0.01-2.0 m/s,respectively.Firstly,the applicability of the methods developed for conventional and large channels were evaluated against the experimental void fraction.And then by the analysis of distribution parameter and drift velocity in several drift flux models,including the Hibiki-Ishii,the Kataoka-Ishii and the Kawanishi models for large diameter,the reasons of their poor accuracy for present tube were also clarified.