三维钝体结构风压分布与绕流特性的大涡模拟研究

Numerical study on pressure and flow characteristics of three-dimensional bluff body by LES

针对风场作用下三维钝体结构的绕流特性与空间风压分布特性,采用大涡模型对其进行了数值模拟研究,以平均风速和脉动风速作为入口边界条件,在稳态分析的基础上对9种不同来流方向的工况进行了瞬态动力分析,再现了钝体绕流的冲撞、分离、重附着等现象,揭示了钝体绕流主、次涡循环区的形成、发展机理,提出了空间风压场分布的一般规律。研究表明:钝体绕流对流场风速剖面影响的强弱程度依次为尾流区、屋顶区、来流区,且对中心区域流场风速剖面的影响要大于两侧流场,并由中心区域向两侧逐渐减小;来流区钝体绕流特性与空间风压分布特性较屋顶区和尾流区稳定,尾流区涡旋的非对称生成、脱落对钝体左右两侧流场的冲撞、分离、重附着等具有重要的影响;来流方向与钝体呈45°或135°夹角时,对尾流风场的影响范围最小,但随着来流方向逐渐垂直于钝体,尾流影响区域也逐渐增大。

This paper investigated resistance characteristics and spatial wind-pressure distribution characteristics of three-dimensional rectangular bluff body by large eddy simulation（LES）.Both mean and fluctuating wind velocity were calculated and adopted as inlet boundary condition to improve accuracy and credibility of numerical simulation.Pressure distributions and vertical and lateral velocity profiles of different models were then investigated and assessed separately in detail.Results show that wind profiles of weak regions are influenced mostly.Influence intensity of flow around bluff bodies shows a gradual decrease from the middle to both sides.Stable mean pressure coefficients can be observed on the front faces.Asymmetric eddy generation and separation in weak regions will have significant influence on the flow impact,separation,and reattachment of both sides of bluff body.The weak regions have the least influence areas in cases of α=45° or α=135°,and then increase gradually when is closing to α=0°,α=90° and α=180°.