Analysis of Flow-Induced Vibrations in Piping Systems and Circular Cylindrical Structures.

Abstract

A new approach to simulate flow-induced vibrations in piping systems and circular cylindrical structures is introduced. In the developed method, three-dimensional unsteady flow is solved by a direct simulation method. Based on the fluid dynamic calculation, fluid forces on structure surfaces(piping inner wall or cylinder surface)are estimated by integrating fluid pressure and shear stress. The calculated fluid forces are translated to finite element nodes in structure surfaces and treated as external forces acting on these surfaces. Then dynamic response of the structures is calculated by using modal analysis or the Newmark-β method. For a full coupling analysis, the moved surfaces become the new coordinate boundaries at the next time step. As an application of the developed method, flow-induced vibrations in an elbow and an array of tubes were evaluated. Turbulent intensity agreed well with experimental data in the unsteady flow analysis and vibration of the elbow was successfully simulated in the dynamic response analysis. For a 3×3 square array, the occurrence of fluid elastic instability could be simulated.