外形参数对纯电动轿车气动阻力的影响研究

发布时间：2018-06-01 13:25

本文选题：纯电动轿车 + 气动阻力　；参考：《吉林大学》2016年硕士论文

【摘要】：面临环境及能源的双重压力,绿色能源日益成为未来发展的总趋势,零排放、无污染的纯电动汽车受到越来越多的青睐。但目前由于配套设施不完善、续驶里程难以满足人们日常所需等问题,发展受到了严重的制约。相较于增大其本身的电池能量密度以提高续航能力而言,降低由汽车外形引起的气动阻力,从而提高纯电动汽车的续驶里程更不失为一种节能环保的好途径。本文选取纯电动轿车进行针对性的外形参数气动阻力影响研究。由于纯电动轿车与传统型轿车在动力与传动技术等方面的差异,引起了车身结构的区别,因此在面临新的条件与限制因素的情况下,有必要对其进行重新的车身总布置研究,近一步研究这些外形参数对纯电动轿车气动阻力的影响。首先,本文对纯电动轿车的主要尺寸、分布及功用进行总结,并探讨在传统轿车以及全新纯电动轿车构架下的电池布置形式的优劣势,在满足中级轿车车身总布置结构条件下,给出了纯电动轿车的空气动力学研究尺寸空间。本文选用Driv Aer轿车模型作为具体研究对象,以汽车风洞实验数据为基准,确定轿车外流场数值仿真方案的各参数,奠定全文数值仿真的研究基础。在此基础上对轿车外流场进行气动特性分析,提出影响纯电动轿车气动阻力的外形参数。基于纯电动轿车外形的空气动力学研究空间,以及所提出的影响气动阻力的外形参数,对纯电动轿车进行整体最佳化研究,选用车身横纵截面曲线上的七个参数控制关键点作为整体设计的参数变量,进行了二十组最优拉丁超立方试验设计,利用三种近似模型建立参数变量与目标函数之间的响应关系,进行可信性分析后,确定R2值为0.950(超过标准值0.9)的克里金近似模型为本方案最佳近似模型,并进一步利用自适应模拟退火算法进行方案寻优。经过寻优后最优方案预测值与实际CFD计算值之间的误差值仅为0.46%,在可接受范围内。经过整体最佳化后的纯电动轿车整车气动阻力系数(9值由0.25883降至0.23592,降低了8.85%。在整体最佳化研究的基础上,又进行了细部优化的研究。选取车头、车顶、车尾三处分别建立控制体,共设置八个参数变量进行研究。选用最优拉丁超立方试验设计方法设计了六十组方案,同样经过可信性分析后确定R2值为0.975的克里金近似模型为最佳近似模型,并进一步利用自适应退火算法对方案寻优。最终所确定的寻优方案预测值与实际计算值之间的误差值为仅0.45%在可接受范围内。经细部优化后,流线型系数Cd*A由0.50793降至0.48438,降低了4.64%;最终方案较原车型的气动阻力系数Cd值降低了13.58%,流线型系数Cd*A值降低了13.13%。综上,基于对纯电动轿车空气动力学研究空间,在全新构架下对其进行外形参数的气动阻力研究,整体最佳化与细部优化均取得了良好的降阻效果,说明纯电动轿车仍有很大的降阻空间,而对各外形参数结果的分析也将对纯电动轿车今后的气动阻力研究做出有益铺垫。
[Abstract]:Facing the dual pressure of environment and energy, green energy is increasingly becoming the general trend of future development. The zero emission and pollution-free electric vehicles are becoming more and more popular. However, due to the imperfect supporting facilities, the driving range is difficult to meet people's daily needs and other problems, and the development has been severely restricted. In order to improve the battery energy density, it is a good way to reduce the aerodynamic drag caused by the shape of the car, so as to improve the driving range of the pure electric vehicle, it is a good way to save energy and environmental protection. In this paper, a pure electric car is selected to study the effect of the aerodynamic drag on the specific parameters of the car. The difference between power and transmission technology causes the difference between the body structure, so in the face of new conditions and restrictions, it is necessary to study the general layout of the body, and study the impact of these parameters on the aerodynamic drag of a pure electric car. First, the main dimensions of the pure electric car are in this paper. The distribution and function are summarized, and the advantages and disadvantages of the battery layout in the traditional car and the new pure electric car frame are discussed. The aerodynamic size space of the pure electric car is given under the condition of meeting the general layout of the medium car body, and the Driv Aer car model is selected as the specific research object. According to the experimental data of the car wind tunnel, the parameters of the numerical simulation scheme of the car outflow field are determined, and the research foundation of the full text numerical simulation is laid. On the basis of this, the aerodynamic characteristics of the car outflow field are analyzed, and the aerodynamic drag of the pure electric car is proposed. The overall optimization of the pure electric car is studied and the seven key control points on the cross section curve of the body are selected as the parameter variables of the whole design. Twenty sets of optimal Latin hypercube test are designed, and the parameter variables and the target functions are established with three approximate models. After the analysis of the response relationship between the numbers, the Krikin approximation model with the R2 value of 0.950 (exceeding the standard value 0.9) is the best approximate model of the scheme, and the adaptive simulated annealing algorithm is further used to optimize the scheme. The error value between the optimal scheme and the actual CFD value is only 0.46% after optimization. In the acceptable range, the aerodynamic drag coefficient of a pure electric car after the overall optimization (9 values decreased from 0.25883 to 0.23592, reduced the study of 8.85%. on the basis of the overall optimization, and then carried out a detailed optimization study. The control bodies were set up in three parts of the car head, the roof and the tail of the car respectively, and the selection of eight parameter variables was studied. " Sixty groups of schemes are designed with the optimal Latin hypercube test design method. The Kriging approximate model with the R2 value of 0.975 is determined as the best approximation model after the reliability analysis, and the adaptive annealing algorithm is further used to optimize the scheme. The error value between the premeasured value and the actual calculated value is only 0. .45% is within the acceptable range. After optimization, the streamline coefficient Cd*A is reduced from 0.50793 to 0.48438, which is reduced by 4.64%. The final scheme is lower than the original model's aerodynamic drag coefficient Cd value by 13.58%, the streamline coefficient Cd*A value is reduced in 13.13%., based on the aerodynamic research space of the pure electric car, and under the new framework, it is carried out under the new frame. The aerodynamic drag of the shape parameters, the overall optimization and the detail optimization have achieved a good drag reduction effect. It shows that the pure electric car still has a large drag reduction space, and the analysis of the results of the various parameters will also make a useful paving for the study of the aerodynamic drag of the pure electric car in the future.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U461.1

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