Dynamic Characteristics Analysis of Cylinders Bundle Coupling System Under Axial Flow

Nuclear reactor fuel assemblies are mainly composed of cylinders bundle (CB), calculating the dynamics characteristics of CB under axial flow can lay a foundation for predicting fretting wear and vibration fatigue. In the paper, the CB coupling dynamic model of forced vibration under pulsating flow is established. And the stability analysis and natural frequency calculation of the CB system under steady flow are compared with the existing results to verify the model. Finally, the Runge-Kutta method is applied to solve the forced vibration equation of the CB under pulsating flow. The influence of the pulsating parameters mu, omega(0) on the amplitude-frequency characteristics and the motion trajectory of the midspan cross section of the CB under forced vibration are analyzed and discussed. The results show that the pulsating parameters have an important influence on the vibration of the CB system.