Study of Flow-Induced Vibrations in a Rotating Double Disk Immersed in a Confined Water

本文对承压水中旋转圆盘的振动特性进行了实验研究。检查了两种类型的盘；一种是直径350 mm、厚1 mm的单盘，另一种是由具有7 mm盘间隙的两个相同盘组成的双盘。双盘的大小与单盘的大小相同。两个磁盘系统都浸入了裹尸布限制的水中。两个系统的遮盖壁和圆盘之间的间隙均为7 mm。改变转速从3rps到7rps，测量了圆盘在两点对角处的位移和盖板壁上的压力波动。数据被记录在磁带上，并被数字化，存储在微型计算机中。我们计算了这些数据的平均值、均方根、功率谱密度和相位角，得到了以下主要结果：1.在一定的转速下，单个圆盘经历了不稳定振动，这种振动在高…时变得更加严重她的旋转速度更快。旋转单盘的振动幅值随转速的增大和减小具有滞后性。圆盘上两对角点之间的不稳定振动模式是异相的。4.旋转速度与圆盘振动主频的关系以及圆盘位移或静态位移的平均值与转速之间的关系也存在滞后。对于双圆盘，我们在不同的转速范围内发现了两个较大的振动，但在驱动轴的固定部分有孔的双圆盘没有发现滞后现象。6.双圆盘的不稳定振动相对于圆盘直径是异相的。7双圆盘经历了屈曲模式的静态变形。根据这些实验结果，我们得出结论：在受限流体中旋转的圆盘经历了三种类型的变形：一个是静态的或屈曲的模式变形，另外两个是具有不同主频的异相模式的振动。较少

This report deals with experimental studies of vibration characteristcs of disks rotating in a confined water. Two type of disks were examined; one was a single disk 350 mm in diameter and 1 mm thick, and the other was a double disk consisting of two identical disks having a disk gap of 7 mm. The double disk size was the same as that of a single disk. Both disk systems were immersed in water confined by a shrouds. The gap between the shroud-wall and the disk was 7 mm for both systems. Changing rotation speed from 3 rps to 7rps, we measured the diaplacement of disk at two points diagonal to each other and pressure fluctuation on the shroud wall. Data were recorded on magneic tape and digitized to be stored in a microcumputer. We calculated the mean, root mean square, power spectral density and phase angle for these data and found the following major results:1. A single disk underwent a unstable vibration a a certain rotation speed and this vibration became a more severe vitration at hig … More her rotation speed.2. Vibration amplitude of a rotating single disk had a hysteresis for increasing and decreasing rotation speed.3. The mode of the unstable vibrations was out-of-phase between two diagonal points on the disk.4.The hysteresis was also found in the relationship between rotation speed and the dominant frequency of the disk vibration as well as in that between the mean value of disk displacement or static displacement and rotation speed.5. For a double disk we found two large vibrations for different rotation speed ranges but no hysteresis was found for the double disk having holes at the fixed part to the driving shaft.6.The unstable vibrations in a double disk was out-of-phase with respect to the disk diameter.7 The double disk underwent a buckling mode static deformation.From these experimental results we concluded-that a disk rotating in a confined fluid undergoes therr type of deformations: one is a static, or buckling mode deformation, the other two were out-of-phase mode vibrations with different dominant frequencies. Less