车用催化器流场的数值模拟与结构优化设计

Numerical Simulation of Flows in Automotive Catalytic Converters With a Novel Deflector and Its Structure Optimum Design

为了改善载体内速度分布,同时减小催化器内的压力损失,建立了基于一种新型导流装置的催化器内部流动的数学模型,并对其流场进行了二维稳态数值模拟。根据仿真结果,分析影响载体内流动特性的主要因素,为导流装置的改进确定方案。具体研究了导流装置结构参数d1:d2的改变对流动特性的影响,分析了速度分布和压力损失的变化规律,得出了一种较优的结构。加装导流装置后,流动在进入扩张管时提前分流,从而使载体前端流速分布更均匀,提高了载体的通过能力,减小了排气背压。

In order to improve the flow distribution and reduce the pressure loss simultaneously,a mathematical model of flow in the automotive catalytic converter with a novel flow deflector is established,and two-dimensional numerical simulation of the steady flows has been performed.According to the results,the main factors influencing the flow distribution in the monolith are discussed in order to improve the former deflector.The effects of deflector structural parameter d1：d2 on the flow distribution have been studied through numerical simulation.By comparing the different results of velocity and pressure loss,an optimum structure has been obtained.It shows that after installing the optimized deflector,flows in the expansion pipe can be diverged in advance,which dramatically improves the velocity distribution,increases the monolith passing capacity,and eventually reduces the back pressure.