多孔蒸汽射流冷凝传热与压力振荡的机理及模型研究

High temperature high-pressure steam jet condensation has been applied to the Automatic Depressurization System in the Third Generation of the large-scale advanced PWR AP1000 and CAP1400 design, due to the great efficient heat and mass transfer ability. In view of this kind of complex heat and mass transfer phenomenon, the engineering tests were conducted to verify the cooling capacity of the steam condensation component design in engineering. However, it has few correlation formulas for calculating condensation heat transfer coefficient or pressure oscillation of the multi-hole steam jet through the mechanism researches. In addition, some scholars have carried out single-hole jet condensation experiments, but there are few experimental studies on double-hole or multi-hole conditions. The interaction behavior and mechanisms of the steam jets between the neighboring holes have not been clarified, and it still has no appropriate calculation models for condensation heat transfer and pressure oscillation of the multi-jets cases. In the present work, minor adaptability modifications are carried out on the existing multi-hole steam condensation test bench. The macroscopic variation laws of multi-hole characteristic parameters in the condensation heat transfer and pressure oscillation process are revealed. Furthermore, the microscopic mechanisms of the "steam-water" and "steam-steam" interfaces variations, lumped steam plumes form, mass and energy dissipation, and periodic oscillations are clarified. The coupling relationship between the heat transfer and pressure oscillation is evaluated, and the theoretical model and semi-empirical correlation of heat transfer and pressure oscillation for multi-hole steam jets are established, which provides the key theoretical basis and design reference for the protective pressure relief design in nuclear power plants.

高温高压蒸汽射流冷凝具有非常高效的传热、传质能力，已应用于大型三代先进压水堆AP1000、CAP1400自动降压系统设计中。针对该类复杂传热传质现象，工程中大多采用工程试验方法来验证此类部件设计的冷却能力，而很少通过机理性研究给出多孔蒸汽射流冷凝换热系数或压力振荡计算关联式。此外，部分学者开展了单孔射流冷凝实验研究，但针对双孔及多孔的实验研究很少，且未阐明多孔间蒸汽射流的相互作用行为及机理，更未能推导适用于多孔射流冷凝传热及压力振荡的计算模型。本课题利用现有多孔蒸汽冷凝工程试验台架，开展多孔射流冷凝机理及模型研究，把握多孔射流冷凝换热与压力振荡宏观变化规律，揭示多孔蒸汽射流“蒸汽-水”、“蒸汽-蒸汽”交界面变化、集总羽流形式、质能耗散、周期性振荡等微观机理，探究冷凝传热与压力振荡的耦合关系，最终建立多孔蒸汽射流冷凝传热与压力振荡理论模型，为核电厂保护性泄压设计提供关键理论基础和设计参考。

高温高压蒸汽射流直接接触式冷凝（DCC）具有非常高效的传热、传质能力，三代先进核电厂自动降压系统通过蒸汽射流冷凝实现反应堆主动、保护性地泄放降压，直接决定一回路高温高压蒸汽冷却吸收效果，但同时伴随显著的压力振荡，因此，多孔蒸汽射流冷凝传热与压力振荡机理研究，对保障反应堆事故冷却可靠性和设备结构安全，具有非常重要的工程应用价值。目前，针对双孔及多孔蒸汽射流冷凝相关研究很少，多孔间蒸汽射流的相互作用行为及微观机理尚不明确，因此，十分必要开展多孔蒸汽射流冷凝机理与模型研究，具有重要的学术价值。. 本项目开展了多孔蒸汽射流冷凝机理实验，基于控制变量实验与精细化三维热工参数测量技术，获得了不同关键输入参数（喷放质量流密度、冷却水温度），不同喷孔几何参数（孔径、孔间距）条件下，蒸汽冷凝传热特征参数（温度分布、穿透长度、膨胀率、换热系数等）与压力振荡特性参数，揭示其宏观变化规律；实验结果发现，由于多孔几何条件、边界条件综合影响，相邻射流汽羽间发生明显的相互重叠、混合行为，汽羽区域“蒸汽-水”汽液交界面的周期性波动，“蒸汽-蒸汽”交界面受力平衡，湍流、夹带、涡旋、扰动等造成的耗散等微观机理，直接决定冷凝换热系数及压力振荡特性。基于关键实验结果，明确多孔蒸汽射流冷凝汽羽集总参数特性，建立多孔蒸汽射流冷凝分析理论计算模型；开展多孔蒸汽射流冷凝关键特性三维数值模拟，并进行实验验证。为反应堆安全降压系统的传热、结构设计提供重要实验及理论支持。. 基于本项目研究成果，发表高水平学术论文8篇，其中SCI论文4篇，EI论文2篇，申请发明专利1项，获软件著作权1项，参加国际学术会议2次，国内学术会议2次。人才培养方面，1人晋升为副教授，并入选北京市科协青年人才托举工程。培养已毕业硕士研究生2名，在读硕士研究生2名，其中2人获得硕士研究生国家奖学金。