切角措施对方柱风压非高斯特性的影响机理  

Effect of chamfer modification on mechanisms of non-Gaussian features of wind pressure on square cylinder

作　　者：杜晓庆[1,2] 方立文 张永平 刘延泰 许汉林 DU Xiaoqing;FANG Liwen;ZHANG Yongping;LIU Yantai;XU Hanlin(Department of Civil Engineering,Shanghai University,Shanghai 200444,China;Wind Engineering and Aerodynamic Flow Control Research Center,Shanghai University,Shanghai 200444,China;School of Mechanics and Engineering Science,Shanghai University,Shanghai 200444,China)

机构地区：[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]上海大学力学和工程科学学院,上海200444

出　　处：《哈尔滨工业大学学报》2021年第4期142-150,共9页Journal of Harbin Institute of Technology

基　　金：国家自然科学基金(51578330,51978392)

摘　　要：为解释切角措施影响方柱风压非高斯特性的作用机理,以标准方柱和切角方柱为研究对象,在雷诺数Re=2.2×10^(4)条件下,采用大涡模拟方法研究了两种方柱的风压特性随风向角的变化规律,重点分析了角部措施对方柱表面风压非高斯特性的影响,并基于瞬时流场结构探讨了角部措施对方柱极值风压的影响规律及其流场作用机理。研究表明:方柱表面风压非高斯分布区域主要集中在方柱侧面后角部位和方柱背风面,而方柱侧面的剪切层再附区域(即分离泡区域)没有明显的风压非高斯现象,切角处理可明显减小方柱后角部位和背风面的风压非高斯区域;方柱表面极值风压的流场机理可分为两类,即方柱侧面后角部位的角部附着涡机理和方柱背风面的卡门涡机理;与标准方柱相比,切角措施使方柱的分离剪切层更贴近于方柱壁面、方柱尾流的卡门涡强度减弱、方柱角部附着涡的强度减弱甚至消失,从而引起极值风压减小和风压非高斯特性的减弱。To explain the mechanisms of non-Gaussian features of wind pressure of the chamfered corner square cylinder,the flow around a sharp corner square cylinder and a chamfered corner square cylinder was investigated by large eddy simulation(LES)method with various wind angles at a Reynolds number of 2.2×10^(4).The effect of corner modification on the non-Gaussian features of wind pressure was analyzed.Based on the instantaneous flow information,the influences of corner modification on extreme wind pressure were discussed and the corresponding flow mechanisms were studied.Results show that the non-Gaussian regions of the sharp corner square cylinder mainly occurred at the rear corner of the lateral surface and the leeward surface.There were no noticeable non-Gaussian features at shear layer reattachment regions(i.e.,separation bubble regions).Chamfer modification could significantly decrease the non-Gaussian regions at the rear corner of the lateral surface and the leeward surface.Flow mechanisms for the occurrence of the extreme wind pressure could be divided into two types,i.e.,attached vortex mechanism at rear corner of the lateral surface and Karman vortex mechanism at the leeward surface.Compared with sharp corner square cylinder,chamfer modification made the separated shear layer closer to the cylinder,produced a weaker Karman vortex,and caused weaker(or even the disappearance of)attached corner vortices,leading to a decrease of extreme wind pressure and smaller non-Gaussian regions.

关 键 词：方柱 角部措施 极值风压 风压非高斯特性 流场机理 

分 类 号：TU973[建筑科学—结构工程]