棒束通道内环状流气液界面行为及形成机理研究

棒束通道中环状流气液界面行为的研究，能为压水堆的事故处理和沸水堆电厂的正常运行提供数据和理论支撑。本研究针对3×3棒束通道中环状流气液波状界面形式进行记录与分析，绘制详细的环状流流型图，并针对其形成机理进行分析。结果表明：棒束通道中的环状流主要有搅混型、未全润湿、平滑边界型、单一波状流、包状扰动波、带状扰动波和带状扰动波叠加液相丧失7种形式；单一波状流是当气相速度较高、液相速度较低时，气液界面上发生的有固定波峰和波谷、以固定速度向上运动的流动形式，其现象可通过Kelvin-Helmholtz型不稳定性理论来解释；当液相流量升高或气相流量减少时，发生单一波状流界面失稳，界面能量增加，进入到包状扰动波或带状扰动波阶段；当能量超过1.6 kPa²/Hz时，界面能量超过底层液膜束缚能力，产生液相丧失型环状流。

Study on Interfacial Behavior and Formation Mechanism of Annular Flow in Rod Bundle Channel

The study of the interfacial behaviors of the annular flow in rod bundle channels can provide data and theoretical support for the accident treatment of PWR and the normal operation of the BWR power plant. In this study, wavy interface forms of annular flow in 3×3 rod bundle channels were recorded and analyzed for drawing detailed regimes of annular flow patterns, and the mechanism analysis was carried out for the formation of interfacial behaviors. The results show that there are seven forms of annular flow in the rod bundle channels, i.e. churn, non-wetting, smooth boundary, single-wave, bag-shaped disturbance-crest, ligament-shaped disturbance-crest and liquid-loss in ligament-shaped disturbance-crest annular flow. When the gas velocity is high and the liquid velocity is low, the single wave flow occurs, of which the interface moves with troughs and crests at a certain upward velocity, and this phenomenon can be explained by the Kelvin-Helmholtz instability theory. When liquid flow rate increases or gas flow rate decreases, the interfacial instability of single-wave occurs, so the energy of the interface increases resulting in changing the annular flow regime into bag-shaped disturbance-crest or ligament-shaped disturbance-crest. When the energy exceeds 1.6 kPa²/Hz (the binding capacity of the bottom liquid film), the flow regime changes to be the liquid-loss annular flow.