Aerodynamics and Wake Flow Characteristics of a Four-Cylinder Cluster
Aerodynamics and Wake Flow Characteristics of a Four-Cylinder Cluster
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DOI：
10.1007/s10494-023-00419-0
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发表时间：
2023-04
期刊：
影响因子：
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通讯作者：
Cung H. Nguyen;Saad Inam;D. Lasagna;Zheng-Tong Xie
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文献类型：
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作者：
Cung H. Nguyen;Saad Inam;D. Lasagna;Zheng-Tong Xie
二维锐缘海崖体群的气动特性和尾流在近场和远场都表现出极其复杂的非定常现象。由于风洞实验和数值模拟的成本很高，对尾流的完整理解和对它们的特性的描述还很缺乏。本文采用大涡模拟（LES）方法，在不同的来流/风向下，对一组排列的方柱进行了大涡模拟（LES），在流向和侧风方向上的分离距离等于方柱的边长，雷诺数基于单个方柱的边长D。入射时的情况表明，在顺风街道/间隙中有明显的通道型流动，在其出口处有不规则的脉动射流，并伴有强烈的大涡脱落。对尾流中侧向力/升力系数和瞬时速度的小波分析表明，远场尾流中大涡结构的特征长度和时间尺度接近于二维团簇尺寸，这就是所谓的“团簇效应”。随着来流入射角的增大，簇效应单调增大。在近场尾流中，在大入射角下，圆柱尺度的流动结构比团簇尺度的流动结构弱得多。在迎角下，总的尾流和气动特性可以通过近似等于2D的尺度来很好地缩放。然而，气缸之间的相互作用显着影响单个气缸的空气动力学性能。集群中单个圆柱的阻力和升力系数彼此之间有很大的不同，并且与单个孤立圆柱的观测结果也有很大的不同。
The aerodynamic behaviour and wake flow of a cluster of two-dimensional sharp-edged bluff bodies exhibits extremely complex unsteady phenomena in both near and far fields. Due to the high cost of wind-tunnel experiments and numerical simulations, a complete understanding of wake flows and a description of their characteristics are lacking. This paper presents large-eddy simulations (LES) in different flow/wind directions for a cluster ofaligned square cylinders, at a separation distance in streamwise and cross-wind directions equal to cylinder side length, and at Reynolds numberbased on the single cylinder side lengthD. The case atincidence shows an evident channel-type flow in the along-wind street/gap, and at its exit an irregularly pulsing jet with an intense shedding of large vortices. The wavelet analyses of the side force/lift coefficient and instantaneous velocities in the wake show that the characteristic length and time scales of the large vortical structures in the far-field wake are close to the cluster size 2D; this is the so called ‘cluster effect’. The cluster effect increases monotonically as the flow incidence angle increases. At a large incidence angle in the near-field wake, the cylinder-scale flow structures are much weaker compared to the cluster-scale structures. At the incidence angle of, the overall wake flow and the aerodynamic characteristics are well scaled by the scale approximately equal to 2D. Nevertheless, the interaction between cylinders significantly affects the aerodynamics performance of the individual cylinders. The drag and lift coefficients of the individual cylinders differ substantially from each other in the cluster, and are significantly different from observations on a single isolated cylinder too.