Experiments on axial-flow-induced vibration of a free-clamped/clamped-free rod for light-water nuclear reactor applications

The flow-induced vibration of a cantilever rod confined in a pipe and exposed to an axial water flow has been experimentally investigated using a simple test piece designed to be informative for water-cooled nuclear reactor fuel rods. The Reynolds number was varied between 7.43 k and 82.5 k: a range that significantly extends the scope of existing data. Measurements were carried out using non-contact techniques: fast video imaging was used to track the rod motion, whilst particle image velocimetry was employed to resolve the flow field. The sources of excitation that sustain the rod vibration include turbulent buffeting, movement-induced excitation, and flow separation at the rod tip, whilst the observed dynamic responses of the rod comprise a fuzzy period-1 motion, a flutter-like large-amplitude oscillation, and buckling. Since both the rod vibration and the flow field are measured, the present data are particularly suited for numerical methodology development and validation.