CAJ | 학술논문

为研究加热面周围边界条件对气泡微细化沸腾的影响，结合实验与数值模拟对加热面低于水箱底面0．5 mm以及与之齐平两种条件下加热面上气泡行为和气泡周围流场进行对比分析。实验结果表明，50 K过冷度下，加热面齐平时，会发生旺盛的MEB现象，而对于加热面下沉时，微细化沸腾现象不发生。数值分析表明，加热面下沉时，气泡周围Marangoni对流被减弱，且气泡顶部的冷凝被大幅削减。这使得气泡稳定地在加热面上形成并逐渐长大，无法形成微细化沸腾现象。因此，气膜周围的Marangoni对流和气液界面上的冷凝过程可能是导致微细化沸腾发生的主要原因。
위연구가열면주위변계조건대기포미세화비등적영향，결합실험여수치모의대가열면저우수상저면0．5 mm이급여지제평량충조건하가열면상기포행위화기포주위류장진행대비분석。실험결과표명，50 K과랭도하，가열면제평시，회발생왕성적MEB현상，이대우가열면하침시，미세화비등현상불발생。수치분석표명，가열면하침시，기포주위Marangoni대류피감약，차기포정부적냉응피대폭삭감。저사득기포은정지재가열면상형성병축점장대，무법형성미세화비등현상。인차，기막주위적Marangoni대류화기액계면상적냉응과정가능시도치미세화비등발생적주요원인。
This study conducts experiments for two cases to demonstrate the effects of the boundary condition around the heating surface on microbubble emission boiling. For one case, the heating surface flushes with the tank bottom and for the other one, the heating surface is about 0.5 mm lower than the tank bottom. Comparison is made for the bubbling performance and flowing velocity under the above two conditions. Experimental results showed that micro?bubble emission boiling ( MEM) occurred vigorously with 50 K subcooling in the first case, while in the second case, the MEB phenomenon did not occur. The data analysis shows that Marangoni convection near the bubble is weakened and the condensation at the vapor?liquid interface is reduced remarkably. Both of these effects cause the bubbles to form and grow up stably on the heating surface without MEB occurring. Therefore, the conclusion is made that Marangoni convection and the condensation at the interface are possibly the reason for microbubble emis?sion boiling.