微小型振荡热管的流动可视化实验

利用高速电荷耦合器件(CCD)对管内径分别为2.5,2,1,0.5 mm的振荡热管进行了可视化研究,记录了不同加热功率下热管内工质准静止和大幅振荡随时间交替变化的情况以及管内工质的流型变化情况.实验中观察到了泡状流、塞状流、半环状流、波环状流和环状流等.结果表明管径对管内的流型变化具有明显的作用.随着管径的减小,汽塞在加热段的形成主要由微/小气泡间的聚合发展演变成以单个气泡的膨胀长大为主.另外,管径的减小还使加热段周围容易生成长汽柱,而冷凝段内的汽塞则易于发生变形和断裂.对微细管径的热管来说,毛细波环状流是其重要特征,在冷凝段容易发生毛细波环状流向毛细塞状流的转变. 

Flow visualization of micro/mini pulsating heat pipes

Flow visualization was investigated for pulsating heat pipes(PHPs) of internal diameters(IDs) 2.5,2,1,0.5mm using a high speed charge coupled device(CCD).Under different heat inputs,both the alternating transformation of the quasi-static phase and oscillation phase vs.time lapse and the flow patterns were recorded.Bubbly flow,slug flow,semi-annular flow,wavy-annular flow and annular flow were observed.Results show that the ID has a significant effect on the flow patterns.As the ID decreases,the formation of...