空气动力学

浅析汽车空气动力学

班级：T813-9

学号：20080130917

姓名：陈建林

指导老师：李楚琳

浅析汽车空气动力学

陈建林

(湖北汽车工业学院机械工程系,湖北十堰,442002)

摘要

随着高速公路的发展，燃油价格的上涨以及越发严格法规的颁布，对汽车的动力性、经济性、操纵稳定性和舒适性提出了越来越高的要求，这使得汽车空气动力学的研究成为汽车行业的重点研究方向之一。采用计算流体力学方法对其性能进行预测，相比风洞试验可以节约资金，缩短新车型开发周期。

面对这种形势，本文针对车身设计提出了一种通过空气动力学性能分析来确定造型的工业设计方法，并对汽车三维外流场进行了数值模拟。

本文首先阐述了轿车外流场数值模拟的整个过程，包括几何、物理模型的建立、湍流模型的选取、边界条件的添加等。所分析的模型选择某豪华轿车l：2实车模型，对实车模型作了如下简化：忽略车身外部突起物如后视镜、刮雨器等部分；没有考虑车轮影响；对车身底部做了简化，没有模拟车底真实的几何形状。为了节省计算耗费，只取实车模型沿纵向对称面的一半。

利用FLUENT进行模型分析，得出车身表面压力分布图、压力场的流态显示，并计算了相应的阻力系数，从而较好地模拟了轿车的外流场，确定了车身空气动力学特性，并对模型在不同的边界条件下和不同的湍流模型下进行了比较和分析，为数值模拟的实用化做了一些有益的尝试。

本文还详细论述了基于空气动力学的车身造型设计方法，以及其两条技术路线，积极探索空气动力学在车身造型中的具体应用，为车身设计提供了新的思路。

最后得出结论，汽车空气动力特性的数值模拟可以辅助汽车设计师，在设计初步完成之后，对其进行流场的数值模拟，对设计提出改进意见，争取达到美学与空气动力性完美结合的程度。

关键词：空气动力学，车身设计流程，车身造型设计，数值模拟

Jianlin Chen

Hubei University of Automotive Technology Department of Mechanical Engineering,Hubei Shiyan,442002 Abstract

With the development of highway,rise of fuel oil price as well As promulgation of even more strict laws and regulations，the request on dynamic characteristics，fuel economy,driving stability and comfort is increasing，which result in the research onautomotive aerodynamics has become all important part of technique in automotive industry．Using computational Fluid Dynamics(CFD)methods to carry on theforecast to it’S performance，can save large amounts of money and reduce the cycle of new vehicle development，compares to the wind tunnel test．In this kind of situation,a car-body model design method based on aerodynamics analysis is present in this paper．

Firstly the thesis elaborated includes the construction of geometric and physical models，selection of turbulence model，definition of boundary conditions．The scale of model is 1：2．The model is simplified：neglecting external heaves such as the rearview mirror and wiper；no considering the effect of the wheels；simplifying the underbody,no simulating the real underbody geometry shape．In order to save the computational expense，half of the model is chosen along the longitudinal symmetry plane．Using the FLUENT analyzed the model．the description of pressure field and car-body surface pressure distribution map are obtained and the drag coefficien were calculated，then the outer flow field of sedan had been simulated well．The aerodynamic characteristics were obtmned，while the comparison and the analysis to the model under different boundary condition and under the different turbulencemodel had carried on，which had made some beneficial attempts for the numericalsimulation practical application．

car-body design method based on aerodynamics iS also discussed in detail in the article，as well as its two technical route，positively explores the method of aerodynamics application on car-body model，which had Present a new way for car-body design．

In the conclusion．the numerical simulation of the automobile aerodynamics characteristic could assist the automobile designer,after the design completed initially, analyses its flow field characteristic，put forward improvement opinion for design proposal，after the design completed initially,strives for achieve the perfect combine of the esthetics and the aerodynamics．

Key words：Aerodynamics，Body design procedure，car-body model design，Numerical simulation