中文摘要：

针对压水堆的复杂结构特点，对堆芯采用多孔介质模型，建立完整的压力容器堆芯模型，使用商用软件CFX对压力容器堆芯的热工水力特性进行数值模拟，得到偏环运行和典型事故工况下冷却剂的热工水力响应特性。计算结果表明：应用多孔介质模型能有效正确直观显示堆芯的冷却剂温度分布情况，在偏环运行工况下堆芯会出现偏心现象，而通过瞬态事故工况计算结果表明堆芯中上部冷却剂温度最高，对压水堆的热工安全具有一定指导作用。

英文摘要：

Background： The coolant flow and heat transfer in the reactor are significant to the safety of pressure water reactor （PWR）. Purpose： This study aims to obtain the coolant flow and heat transfer characteristics in the reactor core. Methods： The complete model of pressure vessel is built by Pro/E, and the thermal hydraulic characteristics of the core are simulated with commercial software CFX by using the porous medium model in the core. Results： The simulation results show that the application of porous media model can display the core coolant temperature distribution effectively and correctly, and the asymmetric operation conditions can cause asymmetric on reactor core. The transient accident calculation results show that the highest temperature of the coolant appears in the upper of the core. Conclusion： The porous media model can be used in the reactor core and it has a certain reference value for the thermal-hydraulic safety of pressurized water reactor.