[Objective] This paper aims to reveal the fretting wear mechanism of tube bundles caused by vibration of foreign objects in heat exchangers

identify the key influencing factors of wear

and obtain the size range of highrisk foreign objects. [Methods] The authors take 2～8 mm cylindrical foreign objects(commonly found on the secondary side of CPR1000-SG type steam generators) as the research objects. Combining relevant models and engineering parameters

a one-way fluid-structure interaction simulation method was adopted to solve the dynamic responses of the position and velocity of foreign objects. Meanwhile

a horizontal water tunnel experimental system was built to conduct flow-induced vibration experiments of foreign objects

so as to verify the accuracy of fluidinduced force calculation in the numerical simulation. Based on the simulation and experimental results

the motion trajectories

drag force characteristics

velocity features

and wear power distribution law of foreign objects with different diameters were systematically analyzed. [Results] The results show that foreign objects with different diameters ultimately determine the distribution characteristics of wear power by correlatively affecting their motion stages

drag force intensity

and velocity modes. In the tube sheet area

the average wear power of cylindrical foreign objects with diameters in the range of 4～6 mm is significantly higher than that of foreign objects with other sizes

among which the 5 mm diameter foreign objects have the peak average wear power. Foreign objects in this size range exhibit a more prominent wear effect on heat transfer tubes. [Conclusion] The research results can provide basic theoretical support and engineering reference for the targeted reduction of heat transfer tube leakage risks and the improvement of nuclear power plant operational safety.