Large Amplitude Aerodynamic Vibration caused by Torsional Vibration of Rectangular Cylinder with a Side Ratio of Five

Abstract

In general, aerodynamic instabilities of bluff bodies are investigated in the very small amplitude region. In this study, a rectangular cylinder with a side ratio of five is used to investigate its large amplitude vibrations under three DOF condition. To understand the responses, the time history analyses are applied by using two kinds of aerodynamic forces: quasi-steady aerodynamic force and the aerodynamic force to which the torsional velocity term is virtually added. Then, the large amplitude torsional vibrations can be divided into the two following phenomena. One is coupled 2DOF large amplitude vibration caused by the torsional vibration, and the other is coupled 2DOF vibration which can be explained by quasi-steady theory.