矩形管道中平板障碍物后旋涡发射特性研究

Investigation of Vortex Shedding behind A Flat Plate in A Rectangular Water Channel

通过理论推导及流动显示实验，研究了矩形管道中平板障碍物后旋涡发射频率及尾流特征。结果得到了旋涡发射频率与雷诺数、平板阻塞率之间的关系，特别是发现了在高阻塞率条件下，当雷诺数增至某个临界值时旋涡发射被抑制，以及尾流存在周期性旋涡发射和无明显周期性的回流区两种不同的流动状态。本文还分析了上述现象的流动机理，即尾流特性主要取决于两边的分离剪切流之间的相互作用。

By means of theory analysis and flow visualization experhoents,the characteristics of the vortex sheddingfrequency and the wake flow patterns behina a flat Pad in a rectanfgular sectioll water Channel have gained an improved understanding .The main results of the flow visualhation Study Show that the two main factors which affect the vortex sheddingfrequency are the blockage ratio and the Reynolds numbs.It was more interestiong to observe that as the blockage ratiO is at the hoer value (more than 0.5), vortex Sheddingcrebs at a critical Valed of the Reynolds number, Mhawbe it waS found that two different types of flow Pattern may existin the near wake,corresponding to the conditions of vortyex Shedding or constrained wake flow for wnich no clearly periwhcbebaviour be seen.In the Present paper the fundamental mechanisms of vortex disc,which revealed thatthe characteristics of wake flow behind wade flow a flat Pcals mainly are determined by interaction the two Shear layers springingtrom the opposide edges of the the flat Plate.