Free vibration analysis of a cylindrical shell eccentrically coupled with a fluid-filled vessel

A theoretical study is presented on the free vibration of a horizontally gu ided, circular cylindrical shell eccentrically submerged in a fluid-filled rigid vessel. In the analysis, it is assumed that the interior and annulus cavities of the shell are filled with an ideal fluid. The Donnell-Mushtari' s shell equations and the velocity potential for fluid motion are used for theoretical formulation. In order to define an eccentricity between the axe s of the shell and the vessel, an additional shifted coordinate system is i ntroduced. In the theoretical formulation, it is necessary that the fluid m otion is described by the modified Bessel functions in the shifted coordina tes. Hence, the Beltrami's theorem is used for the translated forms of the modified Bessel functions. The theoretical results show that the eccentrici ty reduces the coupled natural frequencies for all axial and circumferentia l modes. Additionally, the so-called non-dimensional added virtual mass inc remental factor that reflects the increase of kinetic energy due to the flu id motion is analytically obtained as a function of the eccentricity and mo des of vibration. (C) 2001 Published by Elsevier Science Ltd.