Investigation to the instability Mechanism of Flow Induced Vibration in a Rotating Cylinder-Shaft System Partially Submerged in Water

部分浸没在水中的旋转缸轴系统流激振动失稳机理研究

基本信息

批准号：
03452141
负责人：
HARA Fumio
金额：
$ 3.97万
依托单位：
Science University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

It is well known in vibration field that the rotating cylinder-shaft system undergoes a violent vibration when it is operated at a high speed of rotation over the critical speed. The unstable vibration occurs under a very limited conditions imposed to the rotation speed, submerging water depth, and the natural frequency of the cylinder-shaft system.1) The experimental apparatus was constructed to measure the unsteady fluid force acting on the rotating cylinder when it was forced to oscillate sinusoidally with a constant amplitude. We measured the unsteady fluid force and the displacement of the rotating cylinder simultaneously and evaluated the energy per unit time produced by the unsteady fluid force on the cylinder system. The energy was evaluated for the combinations of experimental parameters; rotation speed, oscillation frequency, amplitude, and submerging water depth.2) We found the unsteady fluid force was of phase-angle lead to the cylinder displacement which resulted in the energy positive for a very limited range of rotation speed and oscillation frequency.3) The cylinder-shaft system underwent an unstable vibration when it was operated under the same condition specified by the above.4) We took video picture of the rotating cylinder and swirling wave generated around the cylinder when it undertook the unstable vibration and analysed the time series video images. It was found the wave generated around the rotating cylinder has the same frequency as the natural one of the cylinder-shaft system when the unstable vibration occurred.5) The research concludes that the flow-induced unstable vibration occurred in the rotating cylinder-shaft system is strongly associated with the fluid wave generated around the cylinder. However the theoretical investigation is still needed to clarify the mechanism governing the unstable vibration which must be based on the experimental results shown in this report.

在振动场中众所周知，旋转的气缸轴系统在高速旋转速度上以临界速度高速旋转时会发生剧烈振动。不稳定的振动发生在非常有限的条件下，施加在旋转速度，淹没水深和气缸轴系统的固有频率下。1）构建实验设备，以测量作用于旋转缸上的不稳定的液体时，当它被迫被迫以恒定的振荡振动时，它是在旋转的圆柱上。我们同时测量了不稳定的流体力和旋转缸的位移，并评估了圆柱系统上不稳定的流体力产生的每单位时间的能量。评估了实验参数组合的能量。旋转速度，振荡频率，振幅和淹没水深。2）我们发现，不稳定的流体力是相角导致的圆柱体位移的，从而导致能量在旋转速度和振动频率非常有限的范围内呈正极。气缸和旋转波在圆柱体进行不稳定振动并分析时间序列视频图像时产生。发现发生不稳定的振动时，旋转缸周围产生的波的频率与气缸轴系统的自然频率相同。5）研究得出的结论是，在旋转气缸轴系统中，流动引起的不稳定振动发生在旋转缸轴系统中与圆柱周围产生的流体有很强的相关。但是，仍然需要进行理论研究以阐明管理不稳定振动的机制，该机制必须基于本报告中所示的实验结果。