中文摘要：

被动阶段分离概念被建议为热转移改进调制流动模式。由流动模式调整，气体趋于在墙附近，液体趋于在试管核心。实验被执行了证实新鲜想法和流动模式调整机制是分析品质上。这份报纸在垂直阶段分离 condenser 试管为一个单个水泡集中于水泡动力学的数字模拟到份量上探索流动模式机制，基于一个多尺度的格子系统和 volume-of-fluid (VOF ) 方法。它被发现那：(1 ) 调制液体电影厚度能被 70% 在赤裸的试管区域与那相比减少；(2 ) 调制水泡旅行速度能被加倍，在环形的区域引起增加的液体速度和速度坡度削弱液体边界层；(3 ) 团和动量在环形的区域和核心区域之间交换的在环形的区域的旅行速度支持的显著地增加的水泡，和收益在核心区域的自我支撑的搏动流动。上述三个因素是为热转移设备的表演改进的利益。

英文摘要：

The passive phase separation concept was proposed to modulate flow patterns for heat transfer enhancement. By the flow pattern modulation, the gas tends to be near the wall and the liquid tends to be in the tube core. Experiment has been performed to verify the fresh idea and the flow pattern modulation mechanism was analyzed qualitatively. This paper focuses on the numerical simu- lation of the bubble dynamics for a single bubble in the vertical phase separation condenser tube to quantitatively explore the flow pattern mechanism, based on a multiscale grid system and the volume-of-fluid （VOF） method. It is found that： （1） the modulated liquid film thickness can be decreased by 70% compared to that in the bare tube region; （2） the modulated bubble traveling veloc- ity can be doubled, causing the increased liquid velocity and velocity gradient in the annular region to weaken the fluid boundary layer; （3） the significantly increased bubble traveling velocity in the annular region promotes the mass and momentum exchange between the annular region and the core region, and yields the self-sustained pulsating flow in the core region. The above three factors are benefit for the performance improvement of the heat transfer facilities.