汽车工程 ›› 2025, Vol. 47 ›› Issue (5): 910-919.doi: 10.19562/j.chinasae.qcgc.2025.05.011

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电动汽车底部流动分离对风阻的动态影响

张倩文1,2(),徐磊2,王庆洋2,徐胜金1   

  1. 1.清华大学航空航天学院,北京 100084
    2.中国汽车工程研究院股份有限公司风洞中心,重庆 401122
  • 收稿日期:2024-05-24 修回日期:2025-01-08 出版日期:2025-05-25 发布日期:2025-05-20
  • 通讯作者: 张倩文 E-mail:zhangqianwen@caeri.com.cn
  • 基金资助:
    国家重点研发计划项目(2022YFE0208000);重庆市博士“直通车”项目(CSTB2023NSCQ-BSX0021)

Dynamic Effect of Underbody Flow Separation on Aerodynamic Drag in Electric Vehicles

Qianwen Zhang1,2(),Lei Xu2,Qingyang Wang2,Shengjin Xu1   

  1. 1.School of Aerospace Engineering,Tsinghua University,Beijing 100084
    2.Wind Tunnel Center,China Automotive Engineering Research Institutue Co. ,Ltd. ,Chongqing 401122
  • Received:2024-05-24 Revised:2025-01-08 Online:2025-05-25 Published:2025-05-20
  • Contact: Qianwen Zhang E-mail:zhangqianwen@caeri.com.cn

摘要:

本文对某量产电动汽车风阻和车底流动分离进行了数值研究。研究表明,在ReL=1.1×107时,车底部流动在尾部分离并向上卷曲形成展向大尺度涡。风阻系数脉动与平均值占比约为3.27%,这对乘坐舒适性及里程预报存在不可忽视的影响。车体背部、底部压力、近尾流中下部、整车气动阻力、车底中后护板近壁面压力以及车底分离流均存在12 Hz的特征频率,而车顶部及两侧的流动分离则无此特征频率,证明车底部的流动分离是引起风阻动态变化的主要原因。

关键词: 电动汽车, 底部流动, 尾流, 风阻

Abstract:

In this paper, an electric vehicle's aerodynamic drag and wake are numerically studied. The results show that the flow separates from the rear of the car may roll up into a large-scale vortex at ReL =1.1 × 107. The ratio of the RMS drag and the mean drag reaches to 3.27%, making an unneglectable effect on ride comfort and mileage prediction. The pressure at the back, the underbody, the middle and lower parts of the near wake, the aerodynamic resistance of the entire vehicle, the pressure near the wall of the rear guard plate in the bottom, and the separation flow at the bottom all have a characteristic frequency of 12 Hz. However, the flow separation at the top and C-pillar of the car does not have this characteristic frequency. It proves that the underbody flow separation at the rear is the main cause of dynamic changes of the aerodynamic drag.

Key words: electric vehicles, underbody flow, wake, aerodynamic drag