Study On Flow Thermal Structure Coupling Of PWR Steam Generator Heat Transfer Tube

Operating experience in pressurized water reactor nuclear power plants has shown that steam generators are one of the nuclear power plants with a high failure rate,with the most accidents occurring on the heat transfer tubes of the steam generators.The problem of fluidic vibration of the heat transfer tube has an important impact on the structural integrity and safety of the steam generator.Therefore,it is of great significance to study the flow field characteristics and rheological vibration of heat transfer tubes of steam generators.In this paper,the flow field characteristics and fluidic vibration response of the primary and secondary sides of the heat transfer tube of a pressurized water reactor steam generator are analyzed and studied.First,a three-dimensional model of a single U-shaped heat transfer tube and a 3×3 tube bundle of the steam generator,which integrates primary convection heat transfer,solid heat conduction,and secondary wall boiling heat transfer processes,is established,and a coupled simulation of the steadystate fluid-thermal structure considering the secondary flow field wall boiling phase change is performed for the natural cycle steam generator heat transfer tube under the best estimated flow life time conditions given by the project.The distribution of fluid pressure,temperature and vapor content of the secondary phase in the primary and secondary flow fields were studied.The structure of the heat transfer tube is also calculated to obtain the distribution of thermal stress and deformation in the steadystate flow field of the heat transfer tube.The calculation model without the support plate was also compared,and the results showed that the effect of the support plate fixation on the heat transfer tube deformation and thermal stress of the steam generator is large and needs to be considered in subsequent calculations.Then,based on the steady-state calculation,the transient bi-directional flowthermal-solid coupling calculation was carried out for the heat transfer tube of the natural cycle steam generator under the best estimated flow life time conditions given in the project,and the variation laws of fluid velocity,temperature and vapor content rate of the secondary side vapor phase in the primary and secondary flow fields with time were studied.By comparing the flow field parameters at different secondary flow velocities,the effect of secondary flow velocity on the transient flow field is obtained.The heat transfer tube structure is also calculated to obtain the distribution of thermal stress and deformation under the transient flow field of the heat transfer tube.In addition,the influence of temperature field on the heat transfer tube structure in the coupling calculation is also compared and analyzed.The results show that the temperature field has a large influence on the heat transfer tube deformation and stress in the two-way coupling calculation and cannot be neglected.Finally,the results of the transient bi-directional flow-thermal-solid coupling simulation of the U-shaped heat transfer tube of the steam generator were analyzed to obtain the flow vibration response law of the heat transfer tube.The results show that the larger the flow velocity,the larger the displacement and the higher the amplitude of the flow vibration of the heat transfer tube.