Vibration analysis of a system of partially-filled interconnected cylindrical shells representing a fast reactor

Dynamics of a system comprising three interconnected partially-filled concentric cylindrical shells is studied. The outermost shell is upright, and is head-supported. The base of the inner shell is attached to that of the outermost shell. The innermost shell is inverted, and is supported through roof. This shell is partially submerged. Height of fluid in all upright shells is same. This system can be considered to represent a fast breeder reactor. Suitable functional forms are considered to describe the fluid's velocity potential, which leads to the dynamic properties through an energy-based approach. Appropriate changes in the parameters of the solution are shown to produce results for multiple fluid–shell systems studied in the past. A parametric study shows that the natural frequencies of the system are most affected by the fluid height. A smaller annular gap between outer vessels led to lower bulging, but greater sloshing frequencies. Influence of the innermost shell on these results was small. The analytical formulation and the results presented in the paper can be used for validation in future studies on a range of fluid–shell systems.