中文摘要：

主要讨论由水槽流动显示实验得到的圆盘绕流结构在上游小圆柱尾迹干扰下的变化，对圆盘前驻点附近逆压区的流动通过氢气泡显示技术进行观察。由实验结果处理得到圆盘前大涡的结构特征（如周期、最大宽度、在周期内结构随时间的变化等）受扰动几何参数的影响。发现无量纲参数L／d（L为小圆柱中心与圆盘迎风面之间的间距，d为小圆柱直径）对圆盘前驻点区域中大涡的形成和发展有重要的影响。圆柱尾迹中涡通量的增加会在圆盘前产生大尺度的涡对，其周期性演化的频率随L／d增加而增加。

英文摘要：

The present work primarily discusses the flow structure around a disk interfering by a fine circular cylinder placed upstream through hydrogen bubble visualization, with focus on the flow in the front stagnation region of the disk. The experimental results revealed the effect of the arrangement of the circular cylinder on the characteristics of the large vortex in front of the disk, such as period, maximum width and evolvement in a specific period. It is shown that the non-dimensional parameter L/d （L is the distance between the cylinder and the disk and d designates the diameter of the circular cylinder） has significant influence on the formation and evolvement of the large vortex. As the vorticity flux increases in the circular cylinder wake,a large counter rotating vortex pair would be invoked in front of the disk,and the frequency of periodic movement of the vortex pair would increase with the L/d.