矩形通道过冷沸腾可视化实验研究
Visualization Experiment of Subcooled Boiling in Rectangular Channel

板状燃料组件冷却剂通道狭窄，与常规圆管通道内的气泡生长不同，其受限流道将引发气泡形变、局部湍流变化等问题，对气泡的聚合、破碎、形变等造成严重影响。为了解矩形窄缝通道内的气泡生长行为和两相流型变化，文章以去离子水为工质，对一面加热三面可视的长宽为0.5 mm × 2.0 mm的矩形窄缝通道内气泡生长过程进行可视化实验研究，给出了在系统压力0.5~1.0 MPa，入口流量50~200 kg/(m2？s)，过冷度低于40 K，沸腾段壁面热流密度100~500 kW/m2条件下的局部空泡份额变化特性，得到了过冷沸腾工况下的气泡生长行为和泡状流到弹状流动区域的流型转变特性，并给出了经可视化图像后处理程序测得的时均空泡份额。
The plate fuel assembly coolant channel is narrow, which is different from the bubble growth in the conventional round tube channel. The restricted flow channel will cause bubble deformation and local turbulence change, which will seriously affect the polymerization, breakage and deformation of bubbles. In order to understand the bubble growth behavior and the change of two-phase flow pattern in a rectangular narrow channel, this paper uses deionized water as the working fluid to conduct a visualization experiment on the bubble growth process in a rectangular narrow channel with a length and width of 0.5 mm × 2.0 mm, which is heated on one side and visible on three sides. The system pressure range of 0.5~1.0 MPa is given. When the inlet flow rate ranges from 50~200 kg/(m2？s), the subcooling degree is less than 40 K, and the wall heat flux in the boiling section ranges from 100~500 kW/m2, the variation characteristics of local voidfractionare obtained. The bubble growth behavior and the flow pattern transformation characteristics of bubble flow to the elastic flow area under the subcooled boiling condition are obtained. The time average void fraction measured by visual image post processing code is also given.