直交流れによる円柱群の流れ方向振動に関する研究(機械力学,計測,自動制御)  [in Japanese] Study on In-Flow Oscillation of Circular Cylinder Arrays Caused by Cross-Flow(Mechanical Systems)  [in Japanese]

The importance of the in-flow oscillation of a single cylinder in cross-flow has been highlighted since an accident in a FBR-type reactor. In-flow oscillations have also been observed in tube arrays. This report is an experimental study on this phenomenon using maximum nine cylinders in a water tunnel. Six cases, one single cylinder, two & three cylinders in parallel & in tandem, and a nine cylinder bundle, are examined. Every cylinder can move only in in-flow direction. The motion of cylinders is measured by the strain gages and by a high-speed digital video camera. The results are compared with the visualized vortex motion. As the results, two exciting mechanisms, symmetric shedding vortex and alternative shedding vortex, are observed, and there is a transition range between these two mechanisms where a large vibration is observed. Then, an additional test has been done to estimate the root cause of the large vibration in the transition range.