Investigation on Gas-Liquid Two-Phase Flow Patterns across an In-Line Tube Bundles

A high-speed video camera was used to study the flow patterns in the rectangular channel of vertical upward cross-flow of air and water in horizontal tube bundles. Experiments were conducted using in-line tube bundles with a pitch-to-diameter ratio of 1.3 and 1.8. Bubbly flow, intermittent flow and mist flow were identified by flow visualization, and a flow map was constructed as a function of gas and liquid superficial velocities. The information of a single-frame was extracted and made into time series. The recurrence quantification analysis method was used to study the dynamic characteristics of information entropy of gas-liquid two phase typical flow patterns and transition flow patterns. The results show that the recurrence plot of entropy series of transition flow patterns shows the process of flow transition. The characterization result showed that the recurrence plot of information entropy could well reflect the evolution characteristics of flow pattern, and the recurrence characteristics quantities were sensitive to the variations of superficial gas velocity and provided an auxiliary tool for investigation of gas-liquid two-phase flow mechanism.