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为进一步揭示绕流现象的形成机理,本文分别对处于层流稳态区、尾流过渡区、剪切层转换区Re分别为26、200、1.4×105的三种典型流态下的单圆柱绕流进行了二维数值模拟研究。Re为26时应用层流模型直接求解N-S方程,而Re分别为200、1.4×105时使用大涡模拟的方法进行计算。数值模拟很好地再现了稳定的涡旋结构、周期性交替脱落的卡门涡街结构、不规则的涡旋结构,在此基础上分析了尾流结构的基本特征及其压强分布规律、平均的流场特性、积分参数(如升力系数、阻力系数、斯特劳哈尔等),并与有关研究成果进行了对比。研究发现,采用不同流动介质时流场特性有所差异,空气为介质时的计算结果更符合实验的成果,而水为介质时计算结果偏差较大,这主要是由尾流涡旋产生的不合理负压造成的。
In order to further reveal the formation mechanism of the flow around, a single cylinder with three typical flow regimes of Reynolds number of 26, 200, and 1.4 × 105 in the steady-state laminar flow region, wake transition region and shear- Flow around a two-dimensional numerical simulation. When Re is 26, the N-S equation is directly solved by using the laminar flow model, and the large-eddy simulation method is used when the Re is 200 and 1.4 × 105, respectively. The numerical simulation shows the stable vortex structure, the Karman vortex structure and the irregular vortex structure with periodic alternation. Based on the analysis, the basic characteristics and pressure distribution of the wake structure are analyzed. The average Flow field characteristics, integral parameters (such as lift coefficient, drag coefficient, Strouhal, etc.), and compared with the relevant research results. The results show that the characteristics of the flow field are different when using different flow media, the calculation results of the air as a medium are more in line with the experimental results, while the calculation results of water as a medium deviate greatly, which is mainly caused by wake vortexes Reasonable negative pressure caused.