矩形柱体气动性能的流场机理研究
杜晓庆1,2,林伟群1,代 钦2,3

(1. 上海大学 土木工程系,上海 200444; 2. 上海大学 风工程和气动控制研究中心,上海 200444;3. 上海大学 上海市应用数学和力学研究所,上海 200444)

矩形柱绕流; 数值模拟; 气动性能; 流场结构; 分离泡; 二次涡

Numerical study on aerodynamic mechanism of rectangular cylinders
DU Xiaoqing1,2, LIN Weiqun1, DAI Chin2,3

(1. Department of Civil Engineering, Shanghai University, Shanghai 200444, China;2. Wind Engineering and Aerodynamic Flow Control Research Center, Shanghai University, Shanghai 200444, China;3. Shanghai Institute of Applied Mathematics and Mechanics, Shan

flow around rectangular cylinder; numerical simulation; aerodynamics; flow structure; separation bubble; secondary vortex

DOI: 10.15986/j.1006-7930.2019.01.009

备注

矩形截面结构在土木工程中有广泛的应用,其气动性能的流场机理有待进一步澄清.采用k-ω SST湍流模型,对宽厚比B/D=1～4的矩形柱绕流进行了数值模拟研究,得到了矩形柱气动性能随宽厚比的变化情况,给出了不同宽厚比矩形柱的流场结构,探究了流场结构、表面风压和气动力之间的内在关系.研究表明:宽厚比B/D=1和2矩形柱的分离剪切层不会发生再附现象,但在B/D=2矩形柱的近尾流中会形成独特的二次涡,二次涡的出现会延缓旋涡脱落速度,造成Strouhal数降低; B/D=3和4矩形柱的分离剪切层会发生再附,在侧面形成分离泡,并导致尾流宽度变窄和平均阻力系数下降,在矩形柱侧面后角附近会出现负压逐渐减弱的压力恢复区.

Structures with rectangular-section are widely used in the field of civil engineering, whose aerodynamic mechanism needs to be clarified further. The flow field around the rectangular cylinders with aspect ratios of B/D=1～4 is simulated using k-ω SST turbulent models. The effects of the aspect ratio on the aerodynamic characteristics and flow fields are investigated. Three categories of flow structure are proposed for various aspect ratios. The relationship between flow structures, pressure fields and aerodynamic forces are discussed as well. Results show that there is no reattachment of separated shear layers for the cylinders of B/D=1 and 2. However, for B/D=2, the special secondary vortices generated in the near wake of the cylinder, which causes a delay of vortex shedding and a noticeable decrease of Strouhal number. As for B/D=3 and 4, the reattachments of the separated shear layers promote the occurrence of separation bubbles on the side surface of the cylinder, which results in a narrower wake width, a reduction of drag force and a recovery of pressure at the side surface near the trailing edge.