汽车外流场的数值模拟.doc

充值下载即送 CAD 图纸, QQ 36396305 I 摘要随着汽车技术的发展以及道路交通的完善,汽车实用车速大大提高,汽车空气动力学成为汽车行业的重点研究方向之一。本文采用 CFD 方法对某轿车进行三维外流场的数值建模。本课题运用 UG 绘制出实车的 1:1 三维模型。在建立仿真模型过程中, 考虑到仿真时间与计算机硬件问题,对实车部分细节做出相应的简化。然后利用 ICEM 软件建立有限元模型。本文采用四面体+ 三棱柱网格混合方案划分网格, 并采用密度体包围整个轿车, 以对其周围计算区域进行网格加密处理, 并对轿车表面面网格做局部细化。选用 Realizablek- ?湍流模型, 并在其近壁面采用标准壁面函数以提高车身表面流动的模拟精度。最后利用 FLUENT 进行模型分析, 得出车身表面压力分布图和速度矢量图, 通过分析整车表面速度和压力特性, 了解气流运动规律和情形。并通过仿真所得结果计算出该轿车的气动阻力系数与升力系数。根据本文仿真结果并结合轿车造型可以看出, 对于轿车, 由于流线型造型特点, 其气阻力系数相对较小, 但是气动升力系数不稳定。而对于轿车这种高速行驶的汽车, 出于安全与稳定性考虑, 降低其气动升力比减小气动阻力有着更实际的意义。关键字:计算流体力学数值模拟气动阻力气动升力充值下载即送 CAD 图纸, QQ 36396305 II Abstract As the development of automobile te chn ology and improved transport fac ilities, The ve hicle` s Pra c tic al Velo c ity has greatly been im p roved, vehi c le aerodynami cs has a lready been one of the key research dir ec tions in the automotive industry. this p aper builds a three-dimensional flow field numerical simulation model for a coupe with the existing method of CFD . The p roject builds the three-dimensional model of real car (l:l) with the use of UG. During the m odeling p roc ess, there are some sim p lifi c ations for some of the details of real c ar, thinking about the simulation time puter hardware problems. Then this essay b uilds the finite element model with the ICEM software. In this p aper, tetrahedral + Prism hybrid mesh program was used, and the whole couple surrounded by density Body to define the grid surface area. Realizable k-? turbulence model used, and S tandard wall function near the wall to enhance the body surface flow simulation ac cura c y. Finally, after the analysis of the model with the use of FLUENT, we obtains the body surface pressure distribution and the velocity vector. through the analysis of vehicle ’s surface sp eed and p ressure chara c teristics, we c an understand the laws and situations for air movement. It’s shows that the simulation results obtained meets the flow field characteristics and laws. Then the coupe ’s aerodynamic resistan