Pressure distribution, fluctuating forces and vortex shedding behavior of circular cylinder with rotatable splitter plates
Pressure distribution, fluctuating forces and vortex shedding behavior of circular cylinder with rotatable splitter plates
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带可旋转分流板圆柱体的压力分布、脉动力和涡脱落行为
DOI：
10.1016/j.jfluidstructs.2011.11.005
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发表时间：
2012-01-01
影响因子：
3.6
通讯作者：
Huang, Z.
中科院分区：
文献类型：
--
作者：
Gu, F.;Wang, J. S.;Huang, Z.
以往对带固定分流板的圆柱绕流的研究表明，固定分流板可以降低阻力和升力，并能明显抑制初涡脱落。本文在雷诺数为3 × 10(4) ~ 6 × 10(4)的范围内，对直径为D （40 mm）的圆柱体进行了风洞实验，该圆柱体上装有10块可绕圆柱体轴线自由旋转的分流板，其长径比为0.5 ~ 6.0。研究了可旋转分流板的附着对压力分布、波动阻力和升力以及旋涡脱落行为的影响。研究发现，由于沿分流板两侧压差的综合作用，分流板旋转成离轴平衡角δ（在尾迹两侧的概率相等），而不是与自由流对齐。板长LID是决定平衡角δ的关键。当L/D >= 4时，δ保持为零，即与流动方向平行。在靠近汽缸的尾迹处，平均压力高于裸汽缸。此外，平均阻力系数和均方根波动升力系数也在很大程度上由delta决定，它们比相应的裸柱小，分别减少了约30%和90%。然而，可自由旋转的分离器板对板偏转的一侧产生平均升力。此外，还给出了脉动力的Strouhal数和相关分析。可视化的流动结构表明，可自由旋转的分流板拉长了旋涡形成区域，抑制了阀体两侧两个剪切层之间的通信。为了比较，还进行了相同尺寸的固定分流板的附加实验。结果表明，两种分流板在减力和抑制涡脱落方面都有各自的优势。(C) 2011 Elsevier Ltd.版权所有。
Previous studies on the flow around a circular cylinder with fixed splitter plates have shown that the drag and lift can be reduced, and the primary vortex shedding can be suppressed obviously. In this study, a wind tunnel experiment on the flow around a circular cylinder with diameter D (40 mm) attached with ten splitter plates freely rotatable around the cylinder axis has been carried out with different ratios of length to cylinder diameter (LID) from 0.5 to 6.0, in a range of Reynolds number from 3 x 10(4) to 6 x 10(4). The influences of the attachment of these rotatable splitter plates on the pressure distribution, fluctuating drag and lift forces and vortex shedding behavior were investigated. It is found that the splitter plates rotate to an off-axis equilibrium angle delta (on either side of the wake with equal probability) rather than align themselves with free stream due to the integrated effect of the pressure difference along the sides of the splitter plates. The plate length LID is crucial in determining the equilibrium angle delta. Longer splitter plate causes smaller angle: delta remains zero, i.e., parallel to the flow direction, for L/D >= 4. The mean pressures in the wake near the cylinder are higher than that of a bare cylinder. Further, the mean drag coefficients and the root-mean-square fluctuating lift coefficients, which are also largely determined by delta are less than those of the corresponding bare cylinder, with a reduction up to about 30% and 90%, respectively. However, freely rotatable splitter plate develops a mean lift force towards the side the plate has deflected. In addition, the Strouhal number of fluctuating forces and correlation analysis are presented. The visualized flow structures show that the freely rotatable splitter plates elongate the vortex formation region, and the communication between the two shear layers on either side of the body is inhibited. For comparison, experiments of attaching fixed splitter plates with the same size were also conducted. The results indicate that the two kinds of splitter plates have their own advantages in force reduction and vortex shedding suppression. (C) 2011 Elsevier Ltd. All rights reserved.