Development of wire-mesh sensor in small bubble visualization based on differential measurement mode.

Gas-liquid two-phase flows are characterized by complicated temporal-spatial structures, such as large Taylor bubbles occurring periodically, unstable huge waves and randomly distributed gas bubbles. Wire-mesh sensor (WMS) is a very popular tomography technology for multiphase flows. The existing WMS, however, fails to visualize the distributed gas bubbles with small sizes. The real-time detection of small-scale bubbly flows still presents significant challenges. In this study, we propose a new conductance wire-mesh sensor (WMS) system operated in a differential measurement mode to realize the visualization of bubbly flows. An experiment of gas-water flows is mimicked to validate the WMS responses. A comparison of differential and non-differential measurement modes in visualizing the gas bubbles has been conducted. By using the differential measurement mode, the WMS visualizations present a good agreement with the flow images recorded by a high-speed camera and indicate a higher accuracy in the gas holdup measurement of bubbly flows.