Investigation of aerodynamic instability vibration of rectangular cylinder based on energy transfer

Abstract

Aerodynamic instability vibration in orthogonal direction of rectangular cylinder of depth to breadth ratio of B/D = 2 was calculated by fluid-structure interaction. The energy transferred from the fluid to the vibrating rectangular cylinder was characterized, and the aerodynamic instability vibration was investigated using energy map obtained from forced vibration calculation.The energy map represents the energy of various frequencies and amplitudes. The energy map was discussed comparing with unsteady aerodynamic forces, phase differences and energy of structural damping. The energy map distribution on the high wind velocity side of vortex induced vibration region is complicated. This is caused by the formation of different vortex patterns depending on the vibration amplitude, which indicates the so-called hysteresis of vortex induced vibration.The zero value on the energy map represents the amplitude of the aerodynamic instability vibration at various wind velocities. The free vibration of a rectangular cylinder was also calculated and the energy map was used to predict the amplitude of the aerodynamic instability vibration. The results showed that the amplitudes of the zero value in the energy map and the vibration amplitudes of the free vibration were in good agreement for both vortex induced vibration and galloping.