柴油机DPF微粒捕集模拟及压降特性研究

Research on DPF particulate trap simulation and pressure drop characteristics of diesel engine

文章利用AVL-FIRE软件建立柴油机颗粒物捕集器(diesel particulate filter,DPF)三维数值仿真模型,并验证模型的准确性;模拟DPF内部流体速度分布特性、碳烟微粒沉积特性、压降分布特性,研究不同废气流量、废气温度、进出口孔道直径比对DPF压降的影响;同时根据所得结论,提出改善DPF工作效率的具体建议。结果表明:DPF进口孔道流体速度沿轴向逐渐减小至0,出口孔道流体速度沿轴向从0逐渐增加;碳烟微粒的沉积沿DPF轴向方向呈“不均匀”分布,且微粒的大部分总是在载体末端被捕集;DPF压降损失构成中,壁面压降损失占主要地位;排气流量越大、温度越高,造成的压降损失越大;不对称孔道结构的进出口孔道直径比越大微粒承载量也越大,产生的压降损失越小。

In this paper,the 3D numerical simulation model of diesel particulate filter(DPF)of diesel engine was established by using AVL-FIRE software,and the accuracy of the model was verified.The fluid velocity distribution characteristics,soot particle deposition characteristics,and pressure drop distribution characteristics within DPF were simulated.The influence of different exhaust gas flow rates,exhaust gas temperature,and diameter ratio of inlet to outlet on DPF pressure drop was studied.According to the conclusions,some suggestions were put forward to improve the efficiency of DPF.The results show that the inlet channel fluid velocity of DPF decreases to zero along the axis and the outlet channel fluid velocity increases from zero along the axis.The deposition of soot particles is distributed unevenly along the axial direction of DPF,and most of the particles are always captured at the end of the carrier.In the composition of DPF pressure drop,wall pressure drop is dominant.The higher the exhaust gas flow and temperature are,the greater the pressure drop is.The larger the diameter ratio of inlet to outlet of the asymmetric channel structure is,the larger the particle bearing capacity is and the smaller the pressure drop is.