Dynamics of circular cylindrical shells in contact with fluid.

This study focuses on the dynamic interactions between finite thin elastic circular cylindrical shells and fluids. The physical coupling phenomenon is explored considering liquid storage tanks and short tubes with an annular flow. Free radial vibrations of tanks are investigated by a classical theoretical analysis, finite element (FE) analysis and experiments. First, the tank-liquid system is modelled mathematically. The effects of axial static compression on shell and fluid modal parameters are investigated. The findings show that the critical parameter does not depend on the liquid level, and the structural resonances are clustered near the instability zone. Second, by applying the FE method (ANSYS) and carrying out holographic tests, it is found that the structural frequencies for n=l are most strongly influenced by the water level. For shells of equal radii, equal filling ratios and different other parameters, the liquid-related reduction in frequency for modes of given wave numbers is approximately identical. Unexpected shell modes of m=l are obtained and their occurrence is found to depend on the shell height. The damping models show that the energy dissipation results from friction at the shell-oil interface. Finally, the effects of a flexible foundation and axial compression are investigated using time-average holographic interferometry. The modal responses of this shell-water system is found to be different from those of the respective theoretical models. Free radial vibrations of tube-flow systems are studied by finite element analysis. It is confirmed that an acoustic medium causes the appearance of “combined” modes not existing in the shell or acoustic spectrum. It is found that the sub-systems retain their uncoupled resonances in regions of strong coupling. A limited mathematical-FE model demonstrates that a compressible flow brings down the structural frequencies and influences the “combined” modes. A criterion for diversion-type shell instability is also found, yet subject to confirmation.

Grantor dc:publisher.institution

Robert Gordon University

Year dc:date.issued

1998

Author dc:creator

• Kruntcheva, Mariana

Advisor dc:contributor.advisor

• R. Kurktchiev

• Circular cylindrical shells
• Physical coupling
• Liquid storage tanks
• Finite element analysis
• Holographic testing
• Structural frequencies

Language dc:language

en

Identifier

oai:rgu-repository.worktribe.com:2807435
https://doi.org/10.48526/rgu-wt-2807435

OAI identifier oai:identifier

oai:rgu-repository.worktribe.com:2807435