圆柱体尾流结构的控制

本文根据水洞观察的结果,分析了圆柱体尾流中,卡门涡街形成的原因是由于流动的不稳定性所产生。根据这一原则,找到了两种控制尾流结构的方法。当雷诺数小于大约200的情况下,在圆柱体“死水区”一侧的边沿,放置一个直径很小的控制圆柱体,可以抑制卡门涡街的产生。另一种方法是在尾流的平均轴线上,放置一个宽度与圆柱体直径相等的平板,同样能够抑制涡街的产生。风洞试验的结果表明,即使在高雷诺数下(亚临界范围内),由于尾流中放置了平板,使得非定常旋涡受到抑制,从而显著地改变了圆柱体上的气动力。

The Control of Flow Structure of the Near Wake behind a Circular Cylinder

Based on the observation and analysis of flow visualization the mechanis of the vortex street has been recognized to be a flow instability probler. According to this understanding, two methods have been found to control the flow structure of the near wake behind a circular cylinder.When Reynolds number is s aller than 200, the vortex street can be co. pletely suppressed by a s all circular cylinder which is placed in the edge of the "dead water region" .The other n ethod is using a split plate of a strean wise di ension co parable with the diameter of the circular cylinder along the longitudina axis of the wake.Wind tunnel tests show that within the subcritical region, even at high Reynoddes nu ber, the aerodyna mic forces were dramaticly changed as a result of placing a split plate in the wake to suppress the unsteady vortices.