基于CFD的车辆进气系统流场仿真与分析

Fluid simulation and analysis for automotive air intake systems based on CFD

针对传统发动机辅助系统中进气系统的设计多采用经验公式,结果不够准确这一问题,提出了基于计算流体动力学(computational fluid dynamics,CFD)的设计方法.通过建立进气系统的三维模型并进行网格划分,选择RNG(renormalization-group)湍流模型建立气相的数学模型,定义适当的边界条件,利用Fluent软件对进气系统气相流动规律进行数值模拟.在充分考虑空气滤清器滤网的影响,将滤网结构设为多孔介质区域的基础上,对比分析3种设计方案内部流场的速度矢量分布和压力分布,以进气阻力为评判准则,确定进气阻力最小的方案2为最佳设计方案.这种方法对进气系统的设计提供了实用的参考.

Generally, the empirical equations are frequently used in the traditional design method of air intake system of engine auxiliary system, which leads to the results inaccuracy, sometimes big deviation exists between the empirical data and calculated data. Aiming at this difficult prob- lem, a design method based on CFD （computational fluid dynamics） was proposed. After estab- lishing the three-dimensional model and meshing the intake system, RNG（renormalization-group） turbulence model was chosen to establish mathematical model of gas phase. Under some defined appropriate boundary conditions, the gas flow-field in air intake system was simulated by Fluent code. Additionally, in order to take the influence of air filter gauze, the structure of air filter was assumed to porous zone and the distribution of speed and pressures corresponding to the three methods were compared. And the air resistance was chosen as the testing criterion to evaluate the quality of this method. Results show that the second program, whose inlet resistance was least to be the best program. The method provides technological reference for the design of intake system.