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Influence of porous media coatings on flow characteristics and vortex-induced vibration of circular cylinders
Journal of Fluids and Structures ( IF 3.4 ) Pub Date : 2021-08-26 , DOI: 10.1016/j.jfluidstructs.2021.103365
Wenyong Yuan 1, 2, 3 , Shujin Laima 1, 2 , Donglai Gao 1, 2 , Wen-Li Chen 1, 2 , Hui Li 1, 2
Affiliation  

The aerodynamic parameters and flow field characteristics of cylinders with and without a porous media coating (PMC) were experimentally investigated in a wind tunnel. This research explored the potential of using a PMC to control vortex-induced vibration (VIV). The PMCs were manufactured with four pores-per-inch values (PPI = 15, 20, 30, and 40) and three depths, (d/D=0.125, 0.25, and 0.5, where d is the depth of the coating and D is the diameter of the bare cylinder). The instantaneous drag and lift forces were measured in static tests. The results showed that all the PMCs could decrease the fluctuation of the forces. The root-mean-square lift force was reduced by up to 98% with a coating of PPI = 15 and d/D=0.5 at Re = 5.2×104. The flow fields were visualized using a particle image velocimetry (PIV) system and analyzed with time-averaged velocity fields, wake velocity profiles, and turbulence kinetic energy distributions. For PMCs with smaller PPI values and greater depths, the wake vortex formed further away from the cylinder. Then the dynamical responses were tested for elastically supported models. Not all the PMCs could suppress the VIV. When PPI < 30, the PMC decreased the VIV amplitude. For each PPI, a greater depth resulted in a lower amplitude. The VIV amplitude for a coated cylinder was reduced to 4% of that for the bare cylinder. When PPI > 30, the PMC enhanced the VIV, with a greater depth resulting in a higher amplitude. When PPI = 30, the PMC could either increase or decrease the VIV amplitude, depending on the depth. The flow fields around the oscillating cylinder were also analyzed to reveal the effect of the PMC on the wake vortex shedding behavior.



中文翻译:

多孔介质涂层对圆柱流动特性和涡激振动的影响

在风洞中实验研究了带有和不带有多孔介质涂层 (PMC) 的气缸的空气动力学参数和流场特性。该研究探索了使用 PMC 控制涡激振动 (VIV) 的潜力。制造的 PMC 具有四个孔每英寸值(PPI = 15、20、30 和 40)和三个深度(d /D=0.125、0.25 和 0.5,其中d是涂层的深度,D是裸圆柱体的直径)。在静态测试中测量瞬时阻力和升力。结果表明,所有的PMCs都可以减少力的波动。使用 PPI = 15 和d /D=0.5Re = 5.2×10 4. 流场使用粒子图像测速 (PIV) 系统进行可视化,并使用时间平均速度场、尾流速度剖面和湍流动能分布进行分析。对于具有较小 PPI 值和较大深度的 PMC,尾涡形成得离圆柱体更远。然后对弹性支撑模型的动态响应进行测试。并非所有 PMC 都能抑制 VIV。当 PPI < 30 时,PMC 降低了 VIV 幅度。对于每个 PPI,较大的深度导致较低的振幅。涂层圆柱体的 VIV 振幅降低到裸圆柱体的 4%。当 PPI > 30 时,PMC 增强了 VIV,更大的深度导致更高的振幅。当 PPI = 30 时,PMC 可以增加或减少 VIV 幅度,具体取决于深度。

更新日期:2021-08-26
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