低雷诺数下的Ahmed模型绕流流场结构分析  

Structural analysis of flow field around Ahmed model at low Reynolds number

作　　者：张彦杰 张光德[1] 严运兵[1] 朱冬涛 周文韬 Zhang Yanjie;Zhang Guangde;Yan Yunbing;Zhu Dongtao;Zhou Wentao(College of Automobile and Traffic Engineering, Wuhan University of Science and Technology, Wuhan 430065, China)

机构地区：[1]武汉科技大学汽车与交通工程学院,湖北武汉430065

出　　处：《武汉科技大学学报》2021年第4期285-294,共10页Journal of Wuhan University of Science and Technology

基　　金：国家自然科学基金资助项目(51307047);中央引导地方科技发展专项(2018ZYYD027).

摘　　要：基于较低雷诺数(1.48×104)条件下的Ahmed模型水洞实验,采用大涡模拟的方法研究了Ahmed模型绕流非定常流场,通过流场时均流线分布及相关频谱特性分析了Ahmed模型外部绕流流场的涡系结构特点及其演化过程,并绘制出该模型的外部流场拓扑结构图。结果表明,Ahmed模型顶部涡与侧向涡是模型前端来流发生了分离卷曲而形成的,顶部涡在向下游流动的过程中强度逐渐减弱,直至到达模型尾部倾斜面上方边缘处时基本消散;模型顶部来流在模型尾部倾斜面上方分离并形成分离泡;模型顶部与侧面来流在其尾部倾斜面两侧形成了C柱涡;在模型尾迹区域分布范围较广的分离泡是模型尾部倾斜面上的下洗流与底部上洗流相互作用的结果;Ahmed模型尾迹区域地面附近不仅存在底部涡,同时还有因模型底部侧向来流造成的侧向间隙涡。Based on a water-tunnel test of Ahmed model at a low Reynolds number(1.48×104),the transient flow field around the Ahmed model was studied via the large eddy simulation method.The structural features and evolution of vortex in the flow field around the Ahmed model were analysed by researching the time-averaged streamline distribution and relevant spectrum characteristics of the flow field,then the topological structure diagram of the external flow field around the model was drawn.The results show that the top vortex and the side vortex of the Ahmed model are formed by the separation and curling of the incoming flow at the front of the model.The intensity of top vortex weakens gradually when it flows downstream,and nearly disappears at the upper edge of the rear slant surface of the model.The incoming flow from the top of the model is separated to form separation bubbles above the rear slant surface of the model.A C-pillar vortex on both sides of the rear slant surface of the model is caused by the incoming flow from the top and the side of the model.Separation bubbles widely distributed in the wake zone of the model are the result of the interaction between the downwash flow from the rear slant surface of the model and the upwash flow from the bottom,and near the ground in the wake zone of the Ahmed model,there is not only a bottom vortex but also a side clearance vortex caused by the side flow from the bottom of the model.

关 键 词：Ahmed模型 低雷诺数 大涡模拟 流场结构 非定常特性 Strouhal数 拓扑结构 

分 类 号：U461.1[机械工程—车辆工程]