Axial-flow-induced vibration (AFIV) of cylindrical structures is frequently encountered in engineering applications. For example, fuel rods in a nuclear reactor may experience lateral vibration resulting from the high momentum, unsteady and axial-flowing coolant. Consequently, the rods may collide with each other and eventually lead to the fuel-rods damage. It is crucially important to reveal the characteristics of vibration and surrounding flow of fuel rods. Computationally and experimentally investigations have been conducted on the turbulent intensity Tu effect on the AFIV of an elastic cylinder or cylinder cluster, with a view to provide an insight into the underlying physics of fluid-structure interaction.
Computational Results: temporal evolutions of the vibration amplitude of an isolated elastic cylinder at different Tu. (a) dimensionless flow velocity u* = 3.49 and (b) u* = 7.92.
Computational Results: contours of instantaneous vorticity ωz* with velocity vectors around an isolated elastic cylinder, (a-d) at longitudinal position z* = 10, (e) z* = 6 and (f) z* = 14. The normalized time t* of subplots (a-d) corresponds to the instants before the buckled state (a,b) and at the buckled state (b,e,f) or during the flutter motion (d); the dashed line denotes the original position of the cylinder. (u* = 7.92). The circles 1 and 2 denote the position of the streamwise vortices around the cylinder.
Experimental results: contours of typical instantaneous vorticity ωz* between two cylinders at high Tu (2.30%-2.91%); (a) Normalized center-to-center cylinder spacing P* = 1.36, u* = 5.23; (b) P* = 1.36, u* = 2.75; (c) P* = 1.57, u* = 5.23; (d) movement of eddy-structure (Mode III-a and III-b).
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