Numerical study of flow-induced vibration in heat transfer tubes of shell-and-tube heat exchangers under ocean conditions

Shell-and-tube heat exchangers (STHXs) are widely used in various industries due to their simple structure and high reliability. This issue is particularly important for floating nuclear power plants (FNPPs), in which heat exchangers serve as safety-relevant components of the ultimate heat sink and residual heat removal systems. However, for offshore STHXs, complex ocean-induced oscillations can lead to severe flow-induced vibrations (FIV) in the heat transfer tubes, posing significant threats to the structural integrity and operational safety of the heat exchanger. In this study, a three-dimensional fluid–structure interaction (FSI) analysis is conducted for an offshore STHX. A hybrid thermal-hydraulic model that combines a porous media approach with localized geometric refinement is developed. The hybrid model is validated against experimental data, and detailed local flow field characteristics near the heat transfer tubes are obtained. In addition, a finite element analysis (FEA) model of the heat transfer tube is created to study the vibration responses under different oceanic oscillatory conditions. The effects of different oscillation modes, periods, and maximum angles on the vibration response of the heat transfer tubes are investigated. The calculation results show that, under identical conditions, the root mean square (RMS) amplitude of the heat transfer tube is greater under roll motion than pitch. Moreover, the RMS amplitude of the heat transfer tube decreases with longer oscillation period and increases with larger maximum oscillation angle. These results provide useful guidance for identifying unfavorable ocean-motion conditions and for the vibration assessment and design optimization of STHXs in FNPPs.