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首页> 外文期刊>International Journal of Heat and Fluid Flow >Effect of a horizontal hole on flow structures around a wall-mounted low- aspect-ratio cylinder
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Effect of a horizontal hole on flow structures around a wall-mounted low- aspect-ratio cylinder

机译：水平孔对壁挂式低纵横比圆柱体周围流动结构的影响

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摘要

To control the vortex structures and separation region of a low-aspect-ratio cylinder wake, a passive flow control method that is to drill a horizontal hole from the front side surface to the rear side surface was proposed for a short circular cylinder having an aspect ratio H/D = 1 with height H and diameter D of 70 mm. The PIV measurements were performed at Reynolds number of 8570 in a circulation water tunnel in order to compare the flow characteristics between the controlling and no-controlling wakes. Furthermore, to study the position effect of the horizontal hole, three kinds of the hole positions having different height h from wall were tested. It was found that the jet flow from a horizontal hole leads to suppress the vortex formation and to reduce the rear separation region. The vorticity, Reynolds shear stresses and TKE were evidently suppressed by the jet flow of the horizontal hole in the rear recirculation zone, resulting in the reduction of the drag acted on the cylinder. Meanwhile, the instantaneous large-scale vortical structures of the rear recirculation zone were broken down into several small-scale vortices by the jet. As increasing the height of hole, the downwash flow is evidently suppressed and the upwash flow is increased. Spanwise vortex shedding is altered from symmetric to asymmetric arrangement.
机译：为了控制低纵横比的圆柱尾流的涡流结构和分离区域，提出了一种被动流控制方法，该方法是从具有短边比的短圆柱体的前表面到后侧面钻一个水平孔。 H / D = 1且高度H和直径D为70 mm。 PIV测量在循环水隧道中以雷诺数8570进行，以比较控制尾流和非控制尾流之间的流动特性。此外，为了研究水平孔的位置效应，测试了三种距墙高度h的孔位置。已经发现，来自水平孔的射流导致抑制涡流的形成并减小了后分离区域。涡流，雷诺剪切应力和TKE明显地被后再循环区域中水平孔的射流所抑制，从而减小了作用在气缸上的阻力。同时，后再循环区的瞬时大尺度涡旋结构被射流分解为几个小尺度涡旋。随着孔的高度增加，明显减少了向下冲洗流量，并且增加了向上冲洗流量。跨度涡旋脱落从对称布置更改为非对称布置。

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