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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。
Based on the results of water hole observation, this paper analyzes the reason that the formation of Karman vortex shed in the wake of cylinder is caused by the instability of flow. Based on this principle, two methods of controlling wake structure were found. When the Reynolds number is less than about 200, placing a control cylinder with a small diameter on the edge of the “dead zone” side of the cylinder suppresses the generation of Karman vortex shedding. Another way is to place a flat plate with the same width as the cylinder on the average axis of the wake, which also suppresses vortex shedding. The wind tunnel test results show that even at high Reynolds numbers (in the subcritical range), unsteady vortices are suppressed due to the presence of plates in the wake, significantly changing the aerodynamic forces on the cylinder.