Bubble size distribution for bubbly-to-slug transition flow in narrow rectangular channel

Abstract

To thoroughly understand the flow structure evolving characteristics in flow regime transition process from bubbly to slug flow in narrow rectangular channel, bubble size distribution (BSD) are experimentally measured by four-sensor conductivity probes. The results show that the T-location distribution fits the measured chord length distribution best in bubbly-to-slug transition flow and the fitting performance becomes worse in slug flow at high void fraction. To solve the problem, two-group bubble fitting for transition flow is proposed and obtains good performance. Function dependence of bubble coalescence and break-up rate is thoroughly analyzed for the transition flow considering its influence on BSD. According to the function dependence and fitting results, empirical correlations are proposed to predict BSD in bubbly and the transition flow. The evolving characteristics of BSD in transition flow are also discussed based on the trends of adjusted parameters in the predicted BSD.