摘要
在非定常数值模拟的基础上,采用本征正交分解(proper orthogonal decomposition,POD)对DrivAer快背车非定常尾迹进行了研究。改进的延迟分离涡模拟(improved delayed detached-eddy simulation,IDDES)仿真结果与实验结果的对比表明该数值方法有效。对汽车尾迹回流区进行POD分析发现,前2阶模态能量占比分别为6.78%和5.61%,合计占总能量的12.39%,模态系数的频谱分析说明前2阶模态对应同一种低频的拟序流动结构,主频为0.216(30Hz);相位分析表明两者相位差为0.455π。对前2阶模态重构的涡量场进行相位平均,发现其对应的拟序流动结构由车体尾迹下剪切层周期性运动主导;前273阶POD模态(能量占比93%)可以很好地重构原流场,极大地降低了自由度。
Based on the unsteady simulation results,proper orthogonal decomposition(POD)was used to analyze the unsteady wake of fastback DrivAer automotive model.The comparison between improved delayed detached-eddy simulation(IDDES)results and the experimental data verifies the effectiveness of simulation method.The POD results of wake recirculation region show that the energy contribution of the first two modes is 12.39%,6.78%and 5.61%respectively.The spectrum analysis indicates that the first two modes correspond to the same low-frequency quasi-sequential flow structure with a dominant frequency of 0.216(30Hz).Phase analysis show that they have a temporal phase shift of 0.455π.The phase average of the vorticity reconstruction field based on the first two modes reveals that quasi-sequential flow structure is found to be dominated by the periodic motion of the shear layer on the underside of the wake.The first 273 POD modes(93%of the energy)can reconstruct the original flow field well and greatly reduce the degree of freedom.
作者
邓韬
杨志刚
贾青
DENG Tao;YANG Zhigang;JIA Qing(Shanghai Automotive Wind Tunnel Center,Tongji University,Shanghai 201804,China;Beijing Aeronautical Science&Technology Research Institute,Beijing 102211,China)
出处
《同济大学学报(自然科学版)》
EI
CAS
CSCD
北大核心
2020年第2期249-256,共8页
Journal of Tongji University:Natural Science
基金
上海市地面交通工具风洞专业技术服务平台(19DZ2290400)
关键词
汽车
非定常尾迹
本征正交分解
分离涡模拟
automotive
unsteady wake
proper orthogonal decomposition
detached-eddy simulation