Author(s)

K. Fujita

Abstract

In this paper, the vibration of circular cylinders subjected to a cross-flow jetted from a narrow gap that exists in the same fluid (hereafter called jet flow or gap flow) is investigated. A problematic example of such jet flow-induced vibration is the vibration damages of fuel rods subjected to the jet flow from the gap between core baffle plates in nuclear power plants. The numerical simulation analysis using a commercial computational fluid dynamics tool (hereafter called CFD) on the vibration of a single circular cylinder and a circular cylinders array composed of six cylinders is performed. In CFD simulation analysis, the equation of continuity, Navier-Stokes equations, are transformed in a discrete system using finite element methods. As for the boundary between structures and fluid, the arbitrary Lagrangian-Eulerianmethod is adopted. Taking the relative position between a cylinder and the axis of jet flow, and the gap width of jet flow as parameters, the vibration behaviors of cylinders subjected to jet flow are investigated. Furthermore, the validity of the simulation analysis is checked comparing with the experimental results that have already been reported by one of the authors. Keywords: free jet, jet flow induced-vibration, vortex shedding vibration, fluid elastic vibration, CFD simulation, stability analysis. 1 Introduction For circular cylinders subjected to uniform cross-flow, large-amplitude vibration due to vortex shedding is observed when the flow velocity reaches a critical value, above which the circular cylinders become unstable again and undergo large

Keywords

free jet, jet flow induced-vibration, vortex shedding vibration, fluid elastic vibration, CFD simulation, stability analysis.