The Flow Pattern and Differential Pressure Fluctuations of Transition Flow across Tube Bundles

A high-speed video camera was used to study the patterns of transition flow 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. In bubbly flow process first captured S bubbly flow. Analyzing the mechanism of flow transition pattern, and a flow map was constructed as a function of gas and liquid superficial velocities. A comparative analysis of transition flow pressure difference fluctuation signal of different flow pattern of both tube bundles, the results show that: pressure differential signal at which bubbly to intermittent and intermittent to mist flow pattern transition showed a trend of decrease. The differential signal amplitude of large pitch ratio is larger than the small pitch ratio. Experiments have found that the gas and liquid superficial velocities to pressure differential signal fluctuation has obvious effect.