载体长度对车用催化转换器流动特性的影响

The influence of vector length on the internal flow in the automotive catalyst converter

采用计算流体动力学模型,利用UG对催化器进行三维建模,在Gambit中进行计算区域网格化和边界条件的定义,用CFD软件FLUENT对三种不同载体长度的催化转换器的速度场、压力场进行了三维稳态流动数值模拟,模拟结果表明:气流在扩张圆锥管壁面附近出现分离产生较强的扰动,造成局部流动损失和载体前气流速度沿径向分布不均匀。载体长度对催化转换器的气流分布有很大影响,对于同一直径的催化转换器,载体长度增加,催化转换器气流分布越均匀,其压力损失越大。

By adopting computational fluid dynamics mode,l three-dimensional model of catalytic converters is created in Gambit by UG,in which calculation of the regional grid and boundary conditions are defined,and three-dimensional steady flow is simulated for velocity field and pressure field of the catalytic converters with three different vector length by using computational fluid dynamic method（CFD software FLUENT）.Simulation results show that：flow separation occurred near the surface in the wall of the expansion cone disturbs much stronger,which cause local flow losses and uneven distribution of air velocity along the radial before the vector.That is to say that the vector length have a great impact on the flow of catalytic converters.For the catalytic converters with same diameter,as the vector length increases,more uniform the air distribution in catalytic converters becomes,and the more the pressure loses.