吉林大学学报(工学版) ›› 2020, Vol. 50 ›› Issue (5): 1635-1644.doi: 10.13229/j.cnki.jdxbgxb20190401

• 车辆工程·机械工程 • 上一篇    

基于双稳态尾迹的方背Ahmed模型减阻

杨志刚1,2,3(),范亚军1,2,夏超1,2(),储世俊1,2,单希壮1,2   

  1. 1.同济大学 汽车学院，上海 201804
    2.同济大学 上海地面交通工具风洞中心，上海 201804
    3.北京民用飞机技术研究中心，北京 102211
  • 收稿日期:2019-04-26 出版日期:2020-09-01 发布日期:2020-09-16
  • 通讯作者: 夏超 E-mail:zhigangyang@tongji.edu.cn;chao.xia@tongji.edu.cn
  • 作者简介:杨志刚(1961-)，男，教授，博士生导师.研究方向：车辆空气动力学.Email:zhigangyang@tongji.edu.cn
  • 基金资助:
    上海市重点实验室项目(18DZ2273300);上海市专业技术服务平台项目(19DZ2290400);国家自然科学基金项目(51905381)

Drag reduction of a square⁃back Ahmed model based on bi⁃stable wake

Zhi-gang YANG1,2,3(),Ya-jun FAN1,2,Chao XIA1,2(),Shi-jun CHU1,2,Xi-zhuang SHAN1,2   

  1. 1.School of Automotive Studies, Tongji University, Shanghai 201804, China
    2.Shanghai Automotive Wind Tunnel Center, Tongji University, Shanghai 201804, China
    3.Beijing Aeronautical Science & Technology Research Institute, Beijing 102211, China
  • Received:2019-04-26 Online:2020-09-01 Published:2020-09-16
  • Contact: Chao XIA E-mail:zhigangyang@tongji.edu.cn;chao.xia@tongji.edu.cn

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摘要：

利用压力传感器和粒子图像测速技术(PIV)对1/4缩比的方背Ahmed模型以及加装船尾结构的模型尾迹进行了精细测量和统计分析，实验雷诺数为9.6×104。背部瞬时压力的统计分析表明：方背Ahmed模型的尾迹在水平方向上呈现出双稳态的特征，即两种打破对称的稳定状态交替出现，每种稳定状态可维持较长的时间尺度。处于两种稳定状态时，背部大概率地呈现出较低的压力，而处于过渡态时相反。通过PIV在水平面的测量，瞬时流场和条件平均的结果均捕捉到了双稳态的流场特征。在模型尾部增加船尾结构后，尾迹的双稳态现象随着船尾长度的增加逐渐被抑制，尾迹涡结构趋于对称，同时尾迹宽度变窄，涡脱落强度减弱，继而造成背压提升，阻力减小。

关键词: 车辆工程, 方背Ahmed模型, 双稳态尾迹, 船尾结构, 粒子图像测速技术

Abstract:

The wake of 1/4 scale square back Ahmed body with or without boat-tail structure was investigated at ReH=9.6×104 by pressure sensor and particle image velocimetry(PIV). The statistical analysis of the instantaneous pressure on the back shows that the wake presents a bi-stable behavior in the horizontal direction, characterized by alternating occurrence of two symmetry-breaking stable states, each can maintain a relatively long-time duration. During the two stable states, a lower pressure on the back presents a high probability, while in the switch state the pressure on the back is higher. The bi-stable behavior was also observed by instantaneous and conditional average PIV results of flow field in the horizontal plane. With boat-tail structure added at the model base, the bi-stable behavior of the wake is gradually suppressed with the increase in the boat-tail length, and the wake vortex structure tends to be symmetrical, the wake width becomes narrow, the vortex shedding strength weakens, leading to higher back pressure and lower drag coefficient.

Key words: vehicle engineering, square-back Ahmed model, bi-stable wake, boat-tail structure, particle image velocimetry(PIV)

中图分类号: 

  • U461.1

图1

试验装置设置及坐标系"

图2

船尾结构"

图3

阻力系数随船尾结构长度的变化"

图4

模型背部平均压力系数Cp"

图5

背部对称点的瞬时压力系数"

图6

背部测压点"

图7

压力梯度的轨迹相图"

图8

不同长度船尾结构的水平方向背压分布时空图"

图9

尾迹区横截面z/H=0.67处的瞬时涡量场及流线"

图10

尾迹区横截面z/H=0.67处的条件平均速度场"

图11

尾迹区横截面z/H=0.67处的速度场"

图12

尾迹区纵截面y/H=0处的瞬时涡量场及流线"

图13

尾迹区纵截面y/H=0处的平均速度场"

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