中文摘要：

蒸汽发生器（SG）在运行过程中主要面临流致振动所导致的传热管破裂事故，而流致振动分析需以SG内的三维两相流场作为输入条件。采用多孔介质模型，对SG二次侧流场进行求解，同时耦合一、二次侧换热，获得SG二次侧速度场、温度场、压力场及流动含气率分布，并获得传热管一维的一、二次侧流体温度和换热系数及传热管温度分布。由于一次侧向二次侧释热极不均匀，SG内流场分布及汽水分离器内的含气率分布极不均匀；汽水分离器内的最大、最小含气率分别为0.62和0.05，该参数可为汽水分离器负载设计提供依据。通过计算还获得弯管区速度分布，该分布可为传热管的流致振动磨损评估提供输入条件。

英文摘要：

The steam generator （SG） suffers from the challenge of tube rupture caused by the flow induced vibration （FIV ） during operation .T he 3D flow characteristics in SG are essential for the analysis of FIV .The secondary side flow field was simulated based on the porous media model ,using the coupled heat transfer from primary to secondary side . T he 3D velocity , temperature , pressure and quality distributions in secondary side ,the one-dimensional temperature and heat transfer coefficient （HTC） distributions of primary and secondary sides as well as the U-tube temperature distribution were obtained .The thermal-hydraulic characteristic distributions in the shell side and the flow vapor quality distribution in separators are significantly uneven due to the non-uniformly distributed heat source released from primary to secondary side .The flow quality distribution in the separators varies from 0.05 to 0.62 ,w hich can be used to the＆amp;nbsp;design for separator load .The velocity distribution in the U-bend region was calculated , w hich provides input conditions for the evaluation of FIV damage of tubes .