Numerical Investigation Of The One Way Fluid-structure-interaction Of Steam Generator

Fluid-structure-interaction(FSI)problems are a common concern in nuclear engineering,especially in the PWR steam generator,this phenomenon can cause stress corrosion,fretting and other problems,seriously affect the life of the heat transfer tubes.Therefore,Numerical investigation on thermal-hydraulic of steam generator have great significance to improve the security of steam generator.According to the steam generator at Daya Bay Nuclear Power Plant,a three-dimensional unit cell model coupling the primary side,the secondary side and tubes is established under the guidance of the similarity principle.The two-fluid model and thermal phase change model are employed,numerical investigation of the thermal-hydraulic characteristic for steam generator is consequently carried out with CFX.The local distribution of primary temperature,the steam quality and heat transfer coefficient of the secondary side,and wall temperature are obtained.Based on the ANSYS-WORKBENCH platform,the fluid results have been transmitted to the structure calculations,the numerical investigation of the one way fluid-structure-interaction of steam generator is performed,the localized distribution of thermal stress and thermal deformation of tubes are captured reasonably.The calculation of the fluid and structure about the two structural steam generators with and without gaps,revealed the impact of thermal-hydraulic characteristics of steam generator and the stress,strain of tubes.The calculated results showed that the deviation between the average heat transfer coefficient with results calculated using Rohsenow's correlation is 4.4%.The average velocity and the cross-sectional average heat transfer coefficient of the secondary side have dramatic changes at the tube support plates,the steam quality at the gaps is higher than that at the flow hole,but the average velocity is lower.The thermal stress of inner wall is slightly higher than outer wall,both trends is consistent.The circumferential dependence of the tube thermal stress shows a periodic characteristic at the tube support plates,the thermal stress of inner wall and outer wall have opposite trend,the change amplitude of the inner wall thermal stress is smaller outer wall.The thermal stress of the structure with gaps is greater than the structure without gaps,the thermal stress changing magnitude of structure with gaps is about twice compared with the structure without gaps in the circumferential direction.With the calculation of tube thermal deformation,the displacement of tube is obtained in each direction,the results can be used to predict the deformation tendency of tube,provide a reference for the design and installation of steam generator.