Non-planar and nonlinear dynamics of wire-wrapped rod subjected to axial flow. Part I: static and dynamic stability

Abstract

Wire-wrapped rods are widely used in liquid metal reactors. Under the excitation of high temperature fluids, the wire-wrapped rod will undergo flow-induced vibration, which is a key factor to evaluate the safe operation of reactors. However, there is still a lack of detailed theoretical research on flow-induced vibration of wire-wrapped rod. In order to deepen the understanding of the dynamic behavior of wire-wrapped rod, the non-planar theoretical model is derived based on Hamilton's principle, and the collision and friction between the wire and adjacent rods are considered. This paper also provides a method to obtain the time history of turbulent excitation force through the power spectral density. Comparison with experimental results strongly validates the reliability of the proposed theoretical model. In the first part of the work, we quantitatively investigate the influence of four system parameters on the critical velocities for both static and dynamic instability of the wire-wrapped rod. The study reveals the existence of post-bucking supercritical Hopf bifurcation and the occurrence of stable limit cycle oscillations at high flow velocities. This theoretical model provides a fundamental framework for further research on the three-dimensional nonlinear vibrations of wire-wrapped rod.