流れの中で横振動する円柱に作用する揚力の分数調波共振

概要

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It is well known that Karman vortices arise in the wake of a circular cylinder placed in a uniform flow. The vortex-induced vibration of a circular cylinder caused by Karman vortices is a key investigation problem for structural design of construction by circular cylinder members. This problem still involves many unclear points. It is because the lift force acting as exciting forces are influenced by many factors such as Kc number, reduced velocity, slenderness ratio, 3-dimensional effect and effect by fluctuation of flow speed etc. It thus can not be easily estimated. This paper presents the measurement of lift force acting on the circular cylinder oscillating transversely in a uniform flow. It concludes from the experimental results that the lift force is increased when the forced oscillating frequency becomes near integer multiple of Strouhal frequency. The shedded vortices are excited at the fraction of the oscillating frequency making a great vortex circulation efficiently in this case.
1998-09-04