Drag reduction of circular cylinders by porous coating on the leeward side
Drag reduction of circular cylinders by porous coating on the leeward side
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DOI：
10.1017/jfm.2016.757
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发表时间：
2017-02-25
影响因子：
3.7
通讯作者：
Ruck, Bodo
中科院分区：
文献类型：
--
作者：
Klausmann, Katharina;Ruck, Bodo
本文描述了圆柱背风面多孔涂层的减阻效果。为了研究涂层效应，在哥廷根型风洞中进行了实验，对不同的圆柱构型和流速进行了系统的阻力测量。阻力测量的压力和粒子图像测速（PIV）的流场测量选定的气缸周围的补充。雷诺数在3 x 10（4）< Re < 1.4 x 10（5）的亚临界范围内变化。结果表明，在背风侧的薄多孔层，无论是在圆柱形状或施加在圆柱表面，导致背风侧的圆柱底部压力的增加。当与没有涂层的圆柱体相比时，它引起阻力的减小并且抑制振荡幅度。不同的配置与不同的关键参数（涂层角度，层厚度和多孔材料的孔径）得到的结果清楚地表明背风涂层的阻力降低和振幅阻尼的潜力。减阻和振幅阻尼的量取决于关键参数的组合。结果表明，在试验雷诺数范围内，降低的阻力系数c（d）几乎不变。测得最大减阻率为13.2%。此外，结果表明，由于涡流区进一步向下游移动，背风涂层圆柱周围的压力波动大幅减少。
The present paper describes the effect of drag reduction of circular cylinders due to a porous coating on their leeward sides. To investigate the coating effect, experiments were conducted in a wind tunnel of Goettingen type, Systematic drag measurements were carried out for different cylinder configurations and flow velocities. The drag measurements were complemented by pressure and particle image velocimetry (PIV) flow field measurements around selected cylinders. The Reynolds numbers were varied in the subcritical range of 3 x 10(4) < Re < 1.4 x 10(5). The results show that a thin porous layer on the leeward side, either incorporated in the cylinder shape or applied on the cylinder surface, leads to an increase of base pressure on the leeward side of the cylinder. It causes a reduction of drag and dampens oscillation amplitudes when compared to a cylinder without coating. Results obtained for different configurations with varying key parameters (coating angles, layer thicknesses and pore sizes of the porous material) clearly indicate the drag reducing and amplitude-damping potential of leeward coating. The amount of drag reduction and amplitude damping depends on the combination of key parameters. It was demonstrated that the lowered drag coefficients c(d) were almost constant in the tested range of Reynolds numbers. A maximum reduction of drag of 13.2 % was measured. In addition, the results revealed a strong reduction of the pressure fluctuations around cylinders with a leeward coating due to the shift of the vortex region further downstream.