对冲式止回阀局部流动特性仿真模拟

当压水堆核电站主泵工况变化时，回路会发生程度不同的水击现象，严重时不仅会产生瞬时超压危害压力边界，也可能造成止回阀失效。对冲式止回阀是一种新型止回阀，其新型的导流结构设计可很好地减轻水击现象，提高核电站运行的安全性。本工作基于FLUENT流体仿真软件，利用动网格及UDF(用户自定义函数)技术，更真实地模拟了阀门关闭过程中冲压管喉部及其联接腔体内的流场与压力分布。模拟结果表明，虽然几何形状的变化会导致关闭过程中局部流速高于其他部位的，但对阀门关闭过程的稳定性影响很小。另外，通过对流场分析发现，阀门关闭过程可分为3个阶段，每一阶段均有其独立特征，为以后阀门结构的改进及可靠性分析提供了依据。

Numerical Simulation of Local Flow Characteristics of Contra-push Check Valve

When the working condition of primary pump of pressurized water reactor (PWR) changes, water hammer phenomena appear in the loop to some extent. Severe water hammer not only would bring incident of instant over pressure and endanger the pressure boundary, but also yield the check valve failure. The contra push check valve (CPCV) is a new kind of check valve. Its new structural design of river diversion can well reduce the water hammer phenomena, thereby enhancing the operational safety of nuclear power plant. The flow field and pressure distribution of the impact tube laryngeal and the connected cavity during the valve closing process were veritably simulated with computational fluid dynamics (CFD) simulation software FLUENT. The dynamic grid and UDF (user-defined function) technology were used in simulation. The results show that although the changes of the geometry will lead to the local flow velocity higher than that of the other part in the closing process, but the impact on the valve closing stability is very small. In addition, through the analysis of the flow field, it is found that the valve closing process can be divided into three stages, each of which shows its own independent characteristics. The study of this paper has provided a basis for future improvement of the valve structure and reliability analysis.