改变车身造型的气动阻力与分轴升力多目标优化

Multi-objective optimization by changing aerodynamic resistance and split shaft lift of the body shape

针对汽车分轴升力与阻力无法综合改善的问题,提出一种造型优化方案。以某SUV为研究对象,建立SUV流场仿真模型并分析外流场气动特性,确定车身需要优化的部位,通过风洞试验验证流场仿真结果的准确性。采用均匀拉丁超立方对造型取样并进行外流场数值仿真计算,通过克里金法建立造型参数与气动系数的对应关系,使用遗传算法生成Pareto前沿解。最终提出3种优化方案综合改善阻力系数和前后轴升力系数,分别使前轴升力系数达到最负值,阻力系数降低2.7%。

As the split-axis lift and drag still need further improvement,this paper proposes a styling optimization scheme.By taking an SUV as the research object,we build an SUV flow field simulation model.Then,the aerodynamic characteristics of the external flow field are analyzed,the parts of the body that need to be optimized are determined,and the accuracy of the results of the flow field simulation is verified through wind tunnel tests.We adopt the uniform Latin hypercube to sample the shape,conduct numerical simulation calculations of the external flow field,and establish the correspondence between the shape parameters and the aerodynamic coefficients through the kriging method.Our Pareto frontier solution is generated by the genetic algorithm.Finally,three optimization schemes are proposed to improve the drag coefficient and the front and rear axle lift coefficients comprehensively.The front axle lift coefficient reaches the lowest value and the drag coefficient is reduced by 2.7%.