Fluid-Structure Interaction Analysis of 3D Effects

摘要

The vibrations of tube bundles immersed in a fluid has been deeply studied during the past 25 years. These bundles have many industrial applications, such as condensers, heat exchangers or nuclear reactors, and their mechanical analysis requires the study of the fluid structure interaction in the tube bundles. Theoretical and numerical studies have been made, and simplified methods have been proposed, such as 2D heterogeneous computations or homogeneization methods. These methods are generally limited to the study of the bundle cross section, because a 3D problem leads to very large sets of equations and requires a quite refined modelization in the case of finite elements study. This paper proposes a 3D computation method for tube bundles, in which the fluid structure interaction is modelized by a 3D model including an explicit representation of both tubes and fluid. The frequency of the fluid coupled eigenmodes and the corresponding mode shapes will be determined for bundles with up to three rings. Interactions between the different eigenmodes of the bending tubes will be analysed, as well as the influence of parameters such as the length of the tubes, their shape, the thickness of the gap between the tubes, the bundle size (i.e. the number of rings) and the confinement (the distance between the surrounding vessel and the bundle).