Narrow rectangular channels are employed in nuclear research reactors that use plate-type nuclear fuels, high heat-flux compact heat exchangers, and high-performance micro-electronics cooling systems. Two-phase flow in narrow rectangular channels is important, and it needs to be better understood because it is considerably different than that in round tubes. In this study, mechanistic models were developed for the flow regime transition criteria for various flow regimes in co-current air-water two-phase flow for vertical downward flow inside a narrow rectangular channel. The newly developed criteria were compared to a flow regime map of downward air-water two-phase flow inside a narrow rectangular channel with a 2.35-mm gap width under ambient temperature and pressure conditions. Overall, the proposed model showed good agreement with the experimental data.

窄矩形通道用于使用板式核燃料、高热通量紧凑型热交换器和高性能微电子冷却系统的核研究反应堆。窄矩形通道中的两相流很重要，需要更好地理解，因为它与圆管中的两相流有很大不同。在这项研究中，针对窄矩形通道内垂直向下流动的并流气水两相流中各种流态的流态过渡标准开发了机理模型。将新开发的标准与在环境温度和压力条件下具有 2.35 毫米间隙宽度的窄矩形通道内向下的气水两相流的流态图进行了比较。全面的，