Turbulence intensity effect on sub-critical vibration for an elastic cylinder subject to axial flow

Abstract

Effect of inlet turbulence intensity on sub-critical vibration is numerical studied for an elastic cylinder subject to axial tubular fluid flow. The cylinder is fixed at both ends and is free to vibrate in any transverse directions. The ANSYS mechanical APDL+FLUENT two-way system coupling is adopted to simulate the fluid-structure interaction. The large eddy simulation model and dynamic model are applied to the modeling of the turbulent flow and re-meshing, respectively. The stiffness and flow velocity are combined into the formulae of the dimensionless flow velocity. The sub-critical vibration of the single cylinder for different inlet turbulence intensity (0%~15%) at the sub-critical velocity (3.3) is studied. The results show that the amplitude of the sub-critical vibration increases by increasing inlet turbulence intensity. With the increase of inlet turbulence intensity, the random vibration occurs. The increasing inlet turbulence intensity is the primary cause of the random vibration. However, there is no buckling for higher inlet turbulence intensity at the sub-critical velocity. With the increasing inlet turbulence intensity, the vibration mode exhibits the first vacuum beam mode at the first, and then the high order mode (e.g., the second mode), and again the first vacuum beam mode at the last.