Abstract Visualization experiments and mechanism analysis were performed to fully investigate the thermal hydraulic behaviors during bottom reflooding within narrow rectangular channel. Qualitative and quantitative analysis of the two-phase flow regimes were conducted by means of high-speed camera. Conclusions can be obtained that five flow regimes were observed, including dispersed flow, inverse annular flow, rewetting front, coalesced bubble flow and isolated bubble flow; when the narrow rectangular channel thickness decreases from 5.0 to 2.0 mm, the rewetting velocity and corresponding critical heat flux decrease severely due to the space limitation, whereas the heat transfer capacity increases in the low superheat region; the locations of rewetting front can be determined both by image processing and ‘temperature variation speed curve’ method, and the mutual authentication results reveal that the visible three-phase contact line and highest point of the temperature variation curve can be regarded as the rewetting front during bottom reflooding.

中文翻译：

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窄矩形河道底部回灌两相流态机理研究

摘要 通过可视化实验和机理分析，充分研究了窄矩形河道底部回灌过程中的热水力行为。两相流态的定性和定量分析是通过高速相机进行的。可以得出结论，观察到五种流态，包括分散流、逆环形流、再润湿前沿、聚结气泡流和孤立气泡流；当窄矩形通道厚度从5.0 mm减小到2.0 mm时，由于空间限制，再润湿速度和相应的临界热通量急剧下降，而在低过热区传热能力增加；再润湿前沿的位置可以通过图像处理和“温度变化速度曲线”方法确定，