A hydroelastic investigation of circular cylindrical shells-containing flowing fluid with different end conditions

This paper presents the effects of different end conditions on the response behavior of thin circular cylindrical shell structures fully in contact with flowing fluid. The investigated end conditions are as follows: simply supported, clamped-clamped, clamped-simply supported and clamped-free (cantilever shell) ends. Additionally, the dynamic responses of a tapered cylindrical shell conveying flowing fluid and simply supported at its ends were investigated. The method employed in this study is a hybrid method-a boundary integral equation method for the calculation of the fluid-structure interaction effects and a finite element method for the structural analysis. In this study, the mathematical model presented before [B. Ugurlu, A. Ergin, A hydroelasticity method for vibrating structures containing and/or submerged in flowing fluid, Journal of Sound and Vibration 290 (2006) 572-596] is extended by applying the direct boundary integral equation method, and by using a higher-order panel method (linear distribution). It should also be said that the method used in this study could be applied to any shape of cylindrical structure in contact with internal and/or external flowing fluid, in contrast to the studies found in the literature. In the analysis of the linear fluid-structure system, it is assumed that the fluid is ideal, i.e., inviscid, incompressible and its motion is irrotational. It is assumed that the flexible structure vibrates in its in-vacuo modes when it is in contact with flowing fluid, and that each mode gives rise to a corresponding surface pressure distribution on the wetted surface of the structure. The in-vacuo dynamic properties of the dry structure are obtained by using a standard finite element software. In the wet part of the analysis, the wetted surface is idealized by using appropriate boundary elements, referred to as hydrodynamic panels. The fluid-structure interaction forces are calculated in terms of the generalized added mass coefficients, generalized Coriolis fluid force coefficients and generalized centrifugal fluid force coefficients. To demonstrate the applicability of the method and assess the influences of the flowing fluid and end support conditions on the dynamic response behavior of the shell structures, the non-dimensional eigenfrequencies and associated eigenmodes are presented as a function of the non-dimensional axial flow velocity, and they compare well with the analytical solutions found in the literature. (C) 2008 Elsevier Ltd. All rights reserved.