类后视镜钝体尾迹分析  

Analysis of Rearview Mirror Bluff Body Wake

作　　者：袁海东[1,2] 杨志刚 单希壮[1,2] 李启良 YUAN Haidong;YANG Zhigang;SHAN Xizhuang;LI Qiliang(Shanghai Automotive Wind Tunnel Center, Tongji University,Shanghai 201804,China;Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management Systems,Shanghai 201804,China;Beijing Aeronautical Science & Technology Research Institute,Beijing 102211,China)

机构地区：[1]同济大学上海地面交通工具风洞中心,上海201804 [2]上海市地面交通工具空气动力与热环境模拟重点实验室,上海201804 [3]北京民用飞机技术研究中心,北京102211

出　　处：《湖南大学学报（自然科学版）》2019年第2期28-35,共8页Journal of Hunan University:Natural Sciences

基　　金：国家重点研发计划课题(2016YFB1200503-04);上海市地面交通工具空气动力与热环境模拟重点实验室(18DZ2273300)~~

摘　　要：后视镜是汽车前侧窗区域重要的气动噪声源,认识后视镜尾迹特征对研究后视镜气动噪声的产生机理有重要意义.搭建类后视镜钝体尾迹风洞试验平台,通过表面油流、热线风速仪和粒子成像测速仪(Particle Image Velocimetry,PIV)测量了类后视镜钝体的时均和瞬时尾迹.通过本征正交分解(Proper Orthogonal Decomposition,POD)识别后视镜尾迹中的大尺度相干结构.试验结果表明:受有限长度特征影响,后视镜尾迹与有限长柱体的尾迹特征类似,尾迹中存在交替涡脱落,尾迹涡脱落特征频率小于0.2.受端部下洗气流的影响,尾迹涡脱落特征频率在流向和展向分布不均.POD分析结果验证了交替涡脱落的存在,交替的涡脱落导致了尾迹回流区的流向和展向振荡现象.因此,后视镜尾迹与有限长柱体的尾迹类似,尾迹涡脱落主要受有限长特征的影响.Rearview mirror is an important source of aerodynamic noise in the front window area of the car. It is of great significance to study the characteristics of the wake of rearview mirror to understand the mechanism of aerodynamic noise of rearview mirror. The wind tunnel test platform was built to measure the time-averaged and instantaneous wake of the rearview mirror bluff body by surface oil streamline, hot wire anemometer, and Particle Image Velocimetry(PIV). Proper Orthogonal Decomposition(POD) was used to identify the large-scale coherent structures in the wake of the rearview mirror. The experimental results show that, due to the finite length feature, the wake of the rearview mirror is similar to that of the finite-length cylinder. Alternating vortex shedding exists in the wake, whose characteristic frequency is less than 0.2. Under the influence of the downwash airflow at the top end, the characteristic frequency of the vortex shedding is unevenly distributed in the streamwise direction and the spanwise direction. The POD analysis results verify the existence of alternating vortex shedding, which leads to the streamwise and spanwise oscillation of the wake recirculation zone. Therefore, the wake of the rearview mirror is similar to that of the finite length cylinder, and the wake vortex shedding is mainly affected by the finite length characteristics.

关 键 词：后视镜 有限长柱体 尾迹 涡脱落 本征正交分解 

分 类 号：U461.1[机械工程—车辆工程]