Non-Linear Vortex-Excited Vibration of a Cylinder in Planar Oscillatory Flow

Abstract

This paper describes an experimental investigation into the non-linear vortex-excited vibration of a cylinder in planar oscillatory flow with emphasis being placed on the amplification of the forces acting on a cylinder caused by the fluid-structure interaction. The experiments were carried out using a water tank which has an internal dimension of 1.0m long and 0.5m deep by 0.5 m wide, and is oscillated in true harmonic horizontal motion. The result shows that the amplifications of the in-line force and transverse force acting on a vortex-excited cylinder are large in the range of Keulegan-Carpenter number (KC) about 5 to 10. It implies that the fluid-structure interaction is large in this range of KC numver. The differences between the flow pattern around the vortex-excited cylinder in resonance condition and those around the rigidly mounted cylinder are observed in the case of KC=8.4.