明渠紊流中涡结构的运动规律

发布时间：2018-10-26 14:04

【摘要】：明渠紊流中随水流迁移的涡结构在传质过程中具有重要作用。为观测涡结构在整个生存期内的运动过程,将两套高频粒子图像测速系统的测量范围沿水流方向拼接,实现流场的大范围测量。将上述方法用于测量摩阻雷诺数为490~870的明渠紊流的纵垂面流场,并结合涡结构跟踪算法,得到了涡的生存时间、运动速度、位移及强度变化等参数。分析表明,涡结构的水平运动与水流同步,但整体有向水面抬升的趋势,在低雷诺数条件下,最大生存时间约10倍涡周转时间,最大垂向位移约0.4倍水深;随着雷诺数的增大,涡结构的量纲一运动速度未发生明显变化,但极限强度和强度变化速率均增大,且极限强度的增加幅度相对较小,使得涡结构的生存时间缩短,纵、垂向位移相应减小。研究结果揭示了生存时间是影响涡结构运动规律的关键变量,初步得到了涡结构运动规律随水流条件的变化趋势。
[Abstract]:The vortex structure with water flow in open channel turbulence plays an important role in mass transfer. In order to observe the motion of vortex structure in the whole lifetime, the measuring range of two sets of high frequency particle image velocimetry system is jointed along the direction of water flow to realize the large-scale measurement of flow field. The method is used to measure vertical and vertical flow field of open channel turbulence with friction Reynolds number of 490,870. The parameters such as survival time, motion velocity, displacement and intensity change are obtained by combining with vortex structure tracking algorithm. The analysis shows that the horizontal motion of the vortex structure is synchronized with the flow of water, but the overall trend is upward towards the water surface. Under the condition of low Reynolds number, the maximum survival time is about 10 times of the vortex turnover time, and the maximum vertical displacement is about 0.4 times of water depth. With the increase of Reynolds number, the dimensionality velocity of vortex structure does not change obviously, but the ultimate strength and intensity change rate increase, and the increasing amplitude of ultimate strength is relatively small, which makes the survival time of vortex structure shorten and longitudinal. The vertical displacement decreases accordingly. The results show that the survival time is the key variable affecting the vortex structure motion, and the variation trend of the vortex structure motion law with the water flow condition is preliminarily obtained.
【作者单位】：北京交通大学土木建筑工程学院;清华大学水利水电工程系;
【基金】：中央高校基本科研业务费专项资金资助项目(2016JBM033) 国家自然科学基金资助项目(51609002)~~
【分类号】：TV133

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