摘要
为研究汽车后视镜外形因素对后视镜空气阻力的影响,以计算流体力学为手段,采用简化的后视镜模型对其进行空气阻力数值模拟.计算区域采用六面体网格,总数为420万个;利用FLUENT求解湍流场,选用k-εRealizable两方程湍流模型,入口和出口分别设定为velocity-inlet和outflow,将无滑移的壁面边界条件应用到后视镜表面及风洞壁面;模拟6种不同形状参数在不同水平下后视镜空气阻力的变化情况.通过与基础模型的对比发现,后视镜的前脸厚度、长宽比、迎风角度以及边缘切向角均对后视镜空气阻力有显著影响,其中随着前脸厚度和迎风角度的增加,其空气动力阻力因数不断减小,而边缘切向角的增加反而导致其空气阻力的增大;后脸深度以及支架长度对后视镜空气阻力并无太大影响.后视镜表面压力因数分布的数值模拟与实验结果的一致性表明,使用数值模拟方法进行后视镜空气阻力研究具有可行性,为后视镜的形状优化建立新的研究方法,对后视镜的工程开发有一定参考意义.
To study the influence of the profile of automotive rear view mirror profile on aerodynamic drag, a numerical simulation on aerodynamic drag of a generic rear view mirror is carried out using Computational Fluid Dynamics （CFD） method based on a simplified rear view mirror model. The computational grids consist of 4. 2 million hexahedral meshes. The turbulent flow is calculated by FLUENT with k-6 Realizable 2-equation model, velocity-inlet and outflow are specified for inlet and outlet respectively, and the boundary condition of no-slip wall is specified on the surface of the rear view mirror and wind tunnel walls. The aerodynamic drag of the rear view mirrors with six kinds of profile parameters is simulated under different magnitude. Compared with the base model, the front face thickness, the length to width ratio, the upwind angle and the tangential edge angle have remarkable effect on aerodynamic drag of rear view mirror; the aerodynamic drag decreases with the increase of front face thickness and upwind angle and increases with the increase of edge angle; the rear face depth and the bracket length have little effect on the aerodynamic drag. The simulation results on surface pressure factor distribution is consistant with the experimental results. So it shows that the numerical simulation method is feasible for the study of the aerodynamic drag of rear view mirror, can provide a new research method on the profile optimization of rear view mirror, and has some reference value to the engineering development of rear view mirror.
出处
《计算机辅助工程》
2009年第4期24-28,共5页
Computer Aided Engineering
基金
高等学校博士学科点专项科研基金(20060247028)
