柴油机DPF湍流通道内微粒形态对微粒输运特性的影响  

Effect of Particle Configuration on Its Movement Characteristics in Turbulent Flow Channel of DPF

作　　者：孙春华[1] 宁智[1] 白振霄[1] 吕明[1] 李元绪 付娟[1] 

机构地区：[1]北京交通大学机械与电子控制工程学院,北京100044

出　　处：《内燃机学报》2017年第3期259-266,共8页Transactions of Csice

基　　金：国家自然科学基金资助项目(51276011);中国博士后科学基金资助项目(2016M591061);中央高校基本科研业务费专项资金资助项目(2016JBM049)

摘　　要：利用建立的椭球形微粒的运动学方程和动力学方程以及湍流场中椭球形微粒的受力及力矩模型,对柴油机微粒捕集器(DPF)湍流通道中微粒的输运特性进行了研究,着重对微粒形态的变化对湍流通道中微粒的运动轨迹、运动方位以及沉降速度的影响进行了分析.结果表明:微粒在壁面附近存在富集现象,且这种现象随着微粒长短半轴比的增加愈发明显;随着气流速度的增加,微粒有向通道内扩散的趋势,且微粒形态对微粒运动轨迹的影响变得显著;在湍流场通道中,椭球形微粒的长轴倾向于与流体流动方向平行,微粒长轴在垂直于壁面方向和展向上的姿态角分布则比较均匀,距壁面量纲为1距离对微粒长轴取向的影响不大;微粒量纲为1沉降速度与微粒形态关系紧密,且随短半轴长的增长并非呈单调变化规律.The movement characteristics of the particles in the turbulent flow channel of diesel engine particulate filter were investigated by using the ellipsoidal particle kinematics and dynamics equations, as well as the force and torque modes. Effects of the particle configuration on its movement direction and trajectory, as well as deposition rate were analyzed. The results show that the particles are aggregated near the wall. This phenomenon becomes more obvious as the particle shape ratio of long axis and short axis increases. In addition, with the increase of air flow rate, the parti- cles show a movement tendency to diffuse into the channel, and the effect of particle shape on its moving trajectory becomes significant. It is also found that in turbulent flow channel, the long axis of the ellipsoidal is parallel to the fluid flow direction. Moreover, the particle distribution is uniform when the long axis＇ direction angle is located across the direction lateral and normal to the wall. The non-dimensional distance to the wall has little effect on the ori- entation of the long axis of the particles. The particle deposition rate is closely related to the particle shape, and is varied non-monotonically with the increase of the short half axis.

关 键 词：柴油机 微粒捕集器 湍流通道 椭球形 微粒 运动 沉降 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]