Passive control on flow structure around a wall-mounted low aspect ratio circular cylinder by using an inclined hole
Passive control on flow structure around a wall-mounted low aspect ratio circular cylinder by using an inclined hole
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DOI：
10.1299/jfst.2017jfst0006
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发表时间：
2017
影响因子：
0.8
通讯作者：
Hiroka Rinoshika;A. Rinoshika;S. Fujimoto
中科院分区：
文献类型：
--
作者：
Hiroka Rinoshika;A. Rinoshika;S. Fujimoto
针对低展弦比（=1）圆柱，为控制和减小后分离区和自由端面涡，提出了一种被动流动控制方法，即利用斜流控制孔（FCH）穿过自由端面到达后端面侧面。为了比较控制尾迹和不控制尾迹的流动特性，在循环水隧道中进行了雷诺数为8,570的高速PIV（粒子图像测速）测量。此外，为了研究FCH的位置效应，对几种FCH模型进行了测试。研究发现，流体从大的后再循环区向上流动到自由端面上的小再循环区。h = 50 mm的FCH气缸减小了后循环区的尺寸，h = 20和35 mm的FCH气缸有效地减小了自由端面的分离区。同时，与标准气缸和其他FCH模型相比，h = 50 mm的FCH气缸的涡度、雷诺剪应力和湍流动能也有所降低。光谱分析表明，圆柱表面涡脱落的主导频率增加。
To control and reduce the rear separation region and the vortex of the free-end surface, a passive flow control method that is to use an inclined flow controlling hole (FCH) passing through the free-end surface to the side of the rear surface was proposed for a low aspect ratio (=1) circular cylinder. The high-speed PIV (Particle Image Velocimetry) measurements were performed at Reynolds number of 8,570 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 FCH, there kinds of the FCH models were tested. It was found that the fluid flows from the large rear recirculation zone upwards to the small recirculation zone on the free end surface through the FCH. The size of rear recirculation zone was reduced by the FCH cylinders with h = 50 mm, and the FCH cylinders with h = 20 and 35 mm effectively diminished the separation region of the free end surface. Meanwhile, vorticity, Reynolds shear stresses and turbulent kinetic energy were also decreased by the FCH cylinders with h = 50 mm comparing with the standard cylinder and other FCH models. Spectral analyses suggest that the dominate frequency of vortex shedding from the cylinder surface increases.