摘要
采用增强型延迟分离涡方法对有/无车轮方背汽车模型的双稳态非定常尾迹进行长时间尺度的数值模拟,捕捉尾迹的左右转换现象,并从时均场和瞬时场分析车轮对尾迹特性的影响;然后采用本征正交分解方法(proper orthogonal decomposition,POD)对背压和尾迹流场进行模态分解,并建立低阶模态流场重构模型,探究双稳态尾迹动力学演化特性。研究结果表明:车轮增强尾迹上洗,导致背部下方压力降低;车轮使得表征双稳态尾迹的水平对称破缺POD模态能量占比显著减小,竖直不对称POD模态能量占比明显增加;后轮内侧流动分离产生的反旋流向涡对,对双稳态尾迹维持在一侧不对称的稳定状态具有破坏作用,即促进了尾迹左右快速小幅度摆动。
The long-time scale bi-stable wake of the square-back vehicle with and without wheels was numerically studied using improved-delayed detached eddy simulation.Several switches of bi-stable wake were successfully captured and the impact of wheels on the wake was analyzed in detail based on both time-averaged and instantaneous flow field.Then,the dominant modes of the instantaneous base pressure and wake flow field were extracted by the proper orthogonal decomposition(POD) method.And low-order mode reconstruction model was applied to investigate the dynamic evolution of the bi-stable wake.The results show that the wheels can enhance the wake upwash,leading to the lower base pressure in the bottom of the base.The POD mode energy fraction of the Lateral-Reflection Symmetry Breaking mode representing the bi-stable wake is significantly reduced by the wheels,while the energy proportion of the vertical asymmetric mode greatly increases.The vortex pair generated by the flow separation from the side of the rear wheel has a destructive effect on the asymmetric steady state maintained by the bi-stable wake,promoting the rapid and modest swing of the wake.
作者
杨志刚
余磊
夏超
范亚军
任静
YANG Zhigang;YU Lei;XIA Chao;FAN Yajun;REN Jing(School of Automotive Studies,Tongji University,Shanghai 201804,China;Shanghai Automotive Wind Tunnel Center,Tongji University,Shanghai 201804,China;Beijing Aeronautical Science&Technology Research Institute,Beijing 102211,China;School of Engineering,University of Liverpool,Liverpool L693GH,UK)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2023年第12期4917-4932,共16页
Journal of Central South University:Science and Technology
基金
国家重点研发计划项目(2022YFE0208000)
国家自然科学基金资助项目(52372360)
上海市地面交通工具空气动力与热环境模拟重点实验室项目(23DZ2229029)。
关键词
方背体汽车
车轮
双稳态尾迹
本征正交分解
square-back vehicle
wheels
bi-stable wake
proper orthogonal decomposition
