Simulation of flow induced vibrations of tube bundle in cross flow

The flow-induced vibration of tubes in a rotated triangular array subject t o cross flow is simulated numerically. In the study, the flow field around the tube bundle is computed by solving the continuity and Navier-Stokes equ ations with assumption of constant fluid properties, and the ks-model for t urbulent Reynolds stress. With the flow field known, the fluid forces on th e tube surfaces can be calculated, and then the displacement of each tube d ue to the fluid force can be evaluated. Iteration is needed to obtain the d ynamic response of the tube structure in the fluid flow. The parameters in the study are inlet velocity of the cross flow and properties of the tube b undle including natural frequency, damping factor, and mass. Based on the t ube response, the critical flow conditions of tube vibration are determined for varying mass damping. Once tube vibrations occur, it is shown that the vibrations of the tubes in the second and fourth tube rows are significant as compared to other tubes. The orbits of the tube vibration look like an ellipse with major axis in the cross-stream direction, implying large lift force on the tubes. The dominant frequency in the spectrum of lift coeffici ents of the tubes is the same as the natural frequency, and the correspondi ng amplitude is increased with increasing the inlet velocity. The calculate d data predicted for the critical reduced velocity agrees well with the dat a by Kassera and Strohmeier [17].