车身俯仰运动对气动升力的影响  

Influence of Vehicle Body in Pitching Motion on Aerodynamic Lift Force

作　　者：黄泰明[1,2] 谷正气[1,3] 陈阵[1] 文琪[1] 罗泽轩 HUANG Tai-ming GU Zheng-qi CHEN Zhen WEN Qi LUO Ze-xuan(State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, Hunan, China Department of Mechanical Engineering, Hunan Institute of Science and Technology, Yueyang 414006, Hunan, China Provincial Collaborative Center of Construction and Development of the Dongting Lake Ecology and Economy Zone, Hunan University of Arts and Science, Changde 415000, Hunan, China)

机构地区：[1]湖南大学汽车车身先进设计制造国家重点实验室,湖南长沙410082 [2]湖南理工学院机械工程学院,湖南岳阳414006 [3]湖南文理学院洞庭湖生态经济区建设与发展省级协同中心,湖南常德415000

出　　处：《中国公路学报》2017年第1期150-158,共9页China Journal of Highway and Transport

基　　金：国家高技术研究发展计划("八六三"计划)项目(2012AA041805);中央财政支持地方高校发展专项资金创新团队项目(0420036017);长沙市科技计划重点项目(K1501011-11);汽车车身先进设计制造国家重点实验室自主课题资助项目(734215002)

摘　　要：为了明确汽车车身俯仰运动对气动升力的影响,建立了某轿车车身俯仰运动模型,并采用大涡模拟对其进行了准静态及瞬态模拟分析。利用动网格技术实现了车身绕前轴中心的正弦俯仰运动,并通过稳态的1∶3模型风洞试验验证了大涡模拟法的准确性。从车身周围流场、车身表面压力等不同的角度对气动升力变化规律及机理进行了分析。结果表明:车身正弦俯仰运动时,瞬态气动升力也随之发生周期性变化,与准静态下气动升力的变化完全不一致,准静态模拟与试验条件下气动升力变化趋势基本一致;瞬态模拟时最大和最小气动升力系数都约为准静态模拟时的3倍;瞬态模拟时,由于流场中气流受到惯性以及黏性作用的影响,导致最大和最小气动升力系数都出现在车身接近水平位置时,与准静态模拟及试验中出现位置完全不同;车身俯仰运动时,车身上表面的压力变化相对较小,而车底板的压力变化很大,且对气动升力有着重要影响,车身从不同方向运动到水平位置时,底板后端的气动压力相差近40N;后轮胎周围的流场变化对气动升力也有重要影响,车身从不同方向运动到水平位置时,后轮罩中心截面上相同位置处和后轮胎后端表面的压力系数最大差值均约为0.4。In order to make clear the change of aerodynamic lift force when the vehicle body takes pitching motion,a vehicle body pitching motion model for a car was established,and the large eddy simulation（LES）method was utilized to do the quasi-steady and transient simulation analysis.The pitching rule of the vehicle body was sinusoid,and the dynamic mesh technology was used to realize the vehicle body pitching motion around the center of front wheel axle.The LES method was validated by 1/3scale wind tunnel test.The change rule and the mechanism of aerodynamic lift force were analyzed by the flow field around vehicle and the pressure distribution on vehicle body.The results show that the aerodynamic lift force takes periodic change when thevehicle body is subjected to pitching motion in sinusoid,which is quite different from that in quasi-steady simulation state,but the trend of the aerodynamic force change on quasi-steady state keeps good agreement with that in the experiments.The maximum and minimum aerodynamic lift force coefficents on transient simulation state are nearly 3times the values on quasi-steady simulation state.On transient simulation state,due to the inertia and viscosity effects of the airflow in the flow field,the maximum and minimum coefficients of aerodynamic lift forces appear when the vehicle body approaches to horizontal position,which is quite different to the position on quasi-steady simulation state.The change of pressure on the upper vehicle body is relatively small when vehicle body takes pitching motion,but the change of pressure on floor is very obviously,which has great influence on the aerodynamic lift force.The difference of the aerodynamic pressures on the rear of the floor is nearly 40 N when the vehicle body moves from different directions to horizontal position.There is a significant influence of the change of flow field around the rear tire on aerodynamic lift force.When the vehicle body moves from different directions to horizontal position,the maximum differences of the pressur

关 键 词：汽车工程 气动升力 大涡模拟 俯仰运动 瞬态模拟 

分 类 号：U469.11[机械工程—车辆工程]