Numerical investigations on flow-induced vibration characteristics of wire-wrapped fuel rod

Abstract

For the wire-wrapped fuel assembly in nuclear reactor, the high-speed scouring of coolant combined with the transverse flow caused by wrapped wire can lead to the vibration of fuel assembly, which in turn induce fretting wear and endanger the integrity of cladding. In this paper, computational fluid dynamics (CFD) method is used to simulate and analyze the flow induced vibration of a single wire-wrapped fuel rod at different flow velocities (2.5–6 m/s), the flow field parameters and solid vibration response characteristics are obtained. Through the analysis of spectrum and statistical method, the power spectral density (PSD) of amplitude is obtained and the vibration displacement, which mainly concentrated in the 3.0–3.4 μm, basically conforms to the normal distribution. The turbulence intensity increases significantly when the fluid passes through the wire, and the pressure pulsation within the boundary layer is enhanced, resulting in greater vibrational displacement of the rod.