Fluent模拟客车流场

毕业论文(论文)

大客车气动性能数值研究

学 院： 交通与车辆工程学院

专 业： 热能与动力工程

姓 名： 员 杰

学 号： 0512108588

指导教师： 齐晓霓

2009年 6 月

中文摘要

摘 要

随着我国经济的发展，汽车工业在国民经济中的比重越来越大，而汽车空

气动力学的的重要性也越来越明显。传统大客车的造型比较简单，气动性能很

差。本文以金旅118为基本模型，应用Pro/E建模，导入Gambit中划分网格，

利用FLUENT软件，采用有限体积法离散控制方程，并利用SIMPLE算法对压

力和速度进行耦合计算。从最简单的长方体开始进行数值模拟计算，首先对长

方体的前部进行逐步改造，然后对其尾部进行变化，得到了某一速度下各车体

的速度矢量图，压力分布图和车身周围的三维流线图，以模拟客车车体形状对

空气阻力系数的影响。最后得出了汽车尾部形状极大影响汽车的气动特性的结

论。这一研究为进一步优化车型，改善汽车的空气动力学特性提供了有效的依

据。

关键词：计算流体力学，客车，数值模拟，空气动力学

I英文摘要

Abstract

With the developments of our country’s economy, the automobile industry of

China has played a very important part in our country’s economy than before. And the

aerodynamic characteristics of the car has become more important than ever. The

shape of traditional bus is simple，so arodynamics is not ideal. In this paper, we study

according to Jinglv118. The geometric models were built by using Pro/E software,

and imported into Gambit. Then the mumerical calculations were performed from the

simplest shape-cuboid by using FLUENT software. The RANS Equaions were

discretized with the FVM method and the equations of the pressure and velocity were

solved with the SIMPLE algorithm in a coupling method. First, the foreside of the

cuboid was modified step by step. Second, the afterbody of the cuboid was modified

to attain vector plots of velocity field、the pressure diagram and the 3D streamlines of

the wake vortex. Finally, we could come to a conclusion that rear configuration

greatly change wake patterns and influence the aerodynamics of car.This study is

beneficial in optimizing the methods to computational fluid dynamic and improving

the aerodynamics of the car.

Keywords：CFD, bus, numerical simulation, aerodynamics

II 目录

目 录

摘 要................................................................................................................II ABSTRACT.........................................................................................................II 目 录...............................................................................................................III 第一章 绪论.........................................................................................................1 1.1 课题研究的意义......................................................................................1 1.2 国内外汽车外流场模拟的研究发展状况..............................................1 1.3 研究的主要内容及目的..........................................................................4 第二章 CFD和FLUENT介绍..............................................................................6 2.1 CFD介绍..................................................................................................6 2.2 FLUENT介绍...........................................................................................8 2.2.1 FLUENT的组成...................................................................................8 2.2.2 FLUENT软件优点.............................................................................10 2.2.3 用FLUENT程序求解问题的步骤....................................................10 2.2.4 FLUENT求解方法的选择.................................................................11 第三章 大客车的外流场数值模拟...................................................................12 3.1 基本假设................................................................................................12 3.2 外流场的控制方程................................................................................12 3.2.1 基本方程...........................................................................................12 3.2.2 湍流模型方程...................................................................................14 3.2.3 SMPLE算法.......................................................................................15 3.3 计算域的计算........................................................................................15 3.4 大客车的模型与网格划分....................................................................16 第四章 计算模拟结果及其分析.......................................................................20 4.1 客车在不同速度下的气动特性分析....................................................20 4.2 四种车型模拟结果及其分析................................................................22 4.2.1 A车型与B车型的压力速度图及分析...............................................22 4.2.2 A车型与C车型的压力速度图及分析...............................................26 4.2.3 A车型与D车型的压力速度图及分析...............................................30 4.2.3 小结...................................................................................................34 第五章 总结与展望...........................................................................................35 参考文献.............................................................................................................37 致谢.....................................................................................................................39