عنوان مقاله [English]
Fluid-Elastic Instability is the most important mechanism among the vibration excitations in heat exchanger tube bundles subjected to cross flow. In this Article, threshold of FEI has been numerically predicted by simulation of incompressible, viscose, and unsteady cross flow through a tube bundle in normal triangular arrangement. In this tube bundle that was being studied, there was a single flexible cylinder surrounded by rigid tubes of bundle. Simulation conditions have been chosen as the scope of experiments performed by Meskell and Fitzpatrick (2003). A finite-volume solver based on Cartesian-staggered grid has been implemented. In addition, the ghost-cell method in conjunction with Great Source Term technique has been employed in order to enforce directly no-slip condition on the cylinders boundaries. Interactions between the fluid and the structure has been counted in a fully coupled manner by means of simultaneous solution of flow field and structural equation of motion in every time step of numerical modeling algorithm. Before giving a solution for the major problem, the accuracy of the solver is validated by simulation of the flow over a single oscillating circular cylinder. The results were completely compatible with the experiments reported in the literature. Eventually, the flow trough tube bundle has been simulated and analyzed by monitoring the drag and lift coefficients, flow visualizing parameters, maximum gap velocity, structural response, trajectory of flexible cylinder and critical reduced velocity.