窄通道内的汽泡核化以及滑移汽泡的影响

摘要

The bubble nucleation in a narrow channel under sub-cooled flow boiling was experimentally studied .The high speed digital camera was used to observe the nuclea-tion and sliding of bubbles .Most of the bubbles in the experiments slide along the heated surface ,but not lift off the surface ,as it is usual in a conventional channel .The nucleation of bubble was different at higher and lower system pressure .The nucleation sites at lower pressure distribute uniformly along the heated surface .However ,most of the nucleation sites at higher pressure concentrate near the onset of nucleation boiling . T he discrepancy of the bubble nucleation sites distribution is mainly caused by the different bubble sliding characteristics at different system pressures .%针对不同压力下窄通道内的过冷流动沸腾汽泡核化进行了实验研究，通过高速摄影技术观察了汽泡的核化和滑移过程。实验结果表明，与常规通道有所不同，窄通道内的汽泡一般不会离开加热壁面而产生浮升现象，汽泡主要沿加热壁面进行滑移运动。不同压力条件下的汽泡核化有较大的差别，较低压力条件下汽泡核化点沿加热壁面分布比较均匀，而压力升高后的汽泡核化点主要集中在沸腾起始点附近，下游核化点数目则相对较少。核化点分布形式的不同主要是由不同压力下汽泡滑移特性的不同所导致的。