Research on effects of rolling motion on a pressurizer surge line based on the fluid-solid-thermal coupling method

•The fluid-solid-thermal coupling analysis of a pressurizer surge line is conducted.•The Large Eddy Simulation approach and the Frame Motion model are used in this study.•The rolling motion causes oscillations in the temperature and stress of surge line.•The effect of different rolling motion conditions on the surge line is investigated. To investigate the effects of rolling motion on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in floating nuclear power plants (FNPP), the finite element simulation platform ANSYS Workbench 19.0 is utilized to conduct the fluid–solid-thermal coupling transient analysis of the surge line under different rolling motion conditions. The Large Eddy Simulation (LES) approach and the Frame Motion model are used in Computational Fluid Dynamics (CFD) analysis. By comparing different calculated results, it is found that rolling motion can significantly improve thermal stratification and reduce the peak thermal stress in some positions of the surge line, but may also result in periodic oscillations in temperature and thermal stress. The effects of the rolling period and the maximum rolling angle on the oscillation amplitude of temperature and thermal stress are investigated. This work provides a reference for evaluating pipeline fatigue damage and the structural integrity of the pressurizer surge line in FNPP under actual ocean conditions.