加热丝上气泡射流的动力学特征

Dynamic performance of bubble jet flows on heated wires

可视化研究加热丝上过冷水沸腾表明,不同尺寸气泡上方均存在由热毛细力诱导的射流,小气泡射流通常较强,而射流方向则呈现多样性。运用示踪粒子显示射流的流场特征,发现射流运动可分3个阶段:泵吸区沿界面速度增加,颈部达最大速度,然后在扩展区速度减小。气泡作为冷源可对其他气泡及其射流产生影响,相邻气泡射流有吸引的趋势,相互作用较强的气泡射流可以合并,气泡运动通常造成相邻气泡射流的非稳态变化,气泡射流相关的物理机制与实验相符。

Various bubble jet flows induced by thermocapillary force were found during sub-cooled boiling on heated wires, and strong jet flows usually existed above very small bubbles, while the jet flow direction was normally dependent upon local conditions. Both jet flow structure and flow field were visually observed and explored by using small particle tracing technology, and the jet flow behavior and dynamic characteristics were discussed together with the experimental measurements. The bubble jet flow was divided into three regions, namely pumping region, neck region and expanding region. The bubble near jet flows was observed to act as a cold source, which prominently affected the adjacent jet flows due to the thermo-capillary effect. The bubble jet flows nearby had attractive interaction due to the thermo-capillary force and bubble sink, and two bubble jet flows would combine into one jet flow due to strong interaction. During bubble departing, the adjacent bubble jet flows experienced an unsteady evolution.