核电站输热管系中蒸汽泡溃灭模拟实验

管路热力输运系统中可能同时出现汽－液两相。当汽－液两相可能接触且存在温差时,会导致汽相急剧冷凝相变,引起蒸汽泡溃灭水锤,导致管系结构破坏。核电站中有大量布局十分复杂的热力输运管道,由于各种原因,蒸汽泡形成和溃灭极易发生。本文针对核电站热力输运管道中汽－液接触后蒸汽饱的形成条件以及溃灭造成的影响进行了分析,用摄影追踪流动显示方法再现了管道中流向发生急剧改变处被冷水隔离的高温蒸汽泡。由于急剧冷凝使得蒸汽体积急剧收缩,环绕的水体产生猛烈碰撞,并监测到该过程中局部压力所产生的瞬间峰值。由于水体对撞运动和逆压梯度,该过程会反复发生多次。利用VOF方法,计算模拟了二维管道系统中蒸汽泡形成的过程。核电站管路的设计和实际操作维护应及时诊断和避免上述问题的发生。

Steam Bubble Collapse of Thermal Pipeline in Nuclear Power Plant

The great temperature difference between two steam and sub cooled water will lead to rapid condensation as soon as two phase fluids meet.There are complicated pipeline nets in a nuclear power plant and steam bubble forms and collapses under some conditions.The paper describes the danger and conditions of steam bubble enveloped.The periods of the bubble forming and collapsing over several cycles were analyzed from photographs selected.The condensation induced the liquid column contact to lead to high pressure pulse.The pressure peaks were recorded.Modified VOF method was employed to simulate the two dimensional phenomenon.It is suggested that avoiding steam bubbles' formation must be considered while constructing the coolant pipeline and the correct operation rules must be made to control flow to keep away steam bubble's collapse.