4 某乘用车整车外流场分析-空气动力学与仿真模型建立.docx
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摘 要
ABSTRACT
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基于DCT的JPEG基本系统的MATLAB实现
摘 要
当前研究汽车整体流场的方法主要有风洞实验法和计算流体力学CFD。风洞实验是将汽车置于风洞里,使汽车静止空气以相同的速度吹向汽车,以此来研究汽车模型与空气流动之间的关系。但是风动实验的周期长,投入大,并受尺寸、结构等各方面的限制,所以模拟出来的存在一定的误差。CFD可以充分模拟汽车周围流场的流动,与风洞实验相比节约成本、大大缩短了实验周期,所以本文就是通过空气动力学数值模拟法(CFD)来对某乘用车整车流场进行分析,并对之车型进行评估改进。
首先,根据某企业的某乘用车车型数据来获得其对应的三维数模。其次,在STAR—CCM+软件中对其数模进行处理,将对研究无影响或影响甚微的整车细节进行优化,以提高计算效率。然后基于空气动力学数值模拟法(CFD)的原理,在ICEM—CFD中来建立优化完成的汽车三维数模的风洞空气动力学模型,并对其与汽车数模进行网格的划分,使研究的模型能够在求解软件中进行接下来的数值求解。接着就是将得出的网格数据导入FLUENT中,设置各项参数,通过求解器来对解决汽车周围流场的计算问题。最后,在CFD—POST中进行最后的后处理,得到汽车与周边流场的诸多数据如压力云图、速度矢量图等,通过其对车型进行分析研究,得出此车的气动阻力系数为0.33,整车前部车型可以做进一步改进来减小前部的气流分离,尾部存在涡流,会增加汽车的气动阻力。从仿真分析的结果过整体来看,整车的阻力呈现减小趋势,汽车周围的流场结构合理。
关键词:CFD;汽车空气动力学;风洞实验
ABSTRACT
At present, wind tunnel experiment and CFD are the main methods to study the overall flow field of automobile. Wind tunnel experiment is to study the relationship between the automobile model and air flow by putting the automobile in a wind tunnel and making the stationary air of the automobile blow towards the automobile at the same speed. However, the period of wind experiment is long, the input is large, and it is limited by the size, structure and other aspects, so there are certain errors in the simulation. CFD can fully simulate the flow field around the vehicle, which saves costs and greatly shortens the experimental period compared with the wind tunnel experiment. Therefore, this paper analyzes the flow field of a passenger vehicle through the aerodynamic numerical simulation method (CFD), and evaluates and improves the vehicle model.
First, the corresponding 3d mathematical model according to the data of a certain passenger car model of a certain enterprise. Secondly, the mathematical model of the vehicle is processed in star-ccm + software to optimize the details of the vehicle with little or no influence on the research, so as to improve the computational efficiency. Then, based on the principle of the aerodynamic numerical simulation method (CFD), the wind tunnel aerodynamic
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