圆柱体双自由度涡激振动轨迹的模型试验

对水平放置的直径 5cm,长120cm的圆柱体开展了双自由度涡激振动模型试验研究. 试验中发现,圆柱体在顺流向上的振动频率表现为"多频"的现象,即不光有2倍横向振动的频率,在某些振动固有频率和约化速度的条件下,还出现了单倍横向振动的频率,从而使圆柱体的轨迹呈现出"卵"形以及"雨滴"形等明显异于传统"8"字形与"新月"形的运动轨迹. 此外,通过研究初步得到了各种其他形式的振动轨迹向"8"字形变化的趋势,并认为不同的横向、顺流向振动固有频率以及流速是导致圆柱体涡激振动轨迹产生多种形式的主要原因. 

AN EXPERIMENT INVESTIGATION ON VIV TRAJECTORIES OF A TWO DEGREE FREE VIBRATION CYLINDER

The paper makes experimental studies on vortex induced vibration of a two degree free vibration cylinder. The cylinder is put horizontally, with the diameter of 5cm and the length of 120cm. The model test could change the frequency of the modeling system vibrating upwards cross and in-line flows by adjusting the number of springs in cross and in-line flows. It has been found the vibrating frequency of the cylinder in in-line flow appears to be "multi-frequency". Under certain vibration frequency and reduced velocity conditions, single-frequency exists in cross flow besides twice-frequency. Consequently, the new trajectories of "egg" and "rain drop" were shown in the tests, different from the traditional trajectories of figure "8" and "new moon", which"" was rarely mentioned in the studies of two degree-of-freedom vortex induced vibration of rigid cylinders with elastic support.