为了在某款摩托车汽油机缸内实现废气再循环 (exhaust gas recirculation，EGR)分层以减少泵气损失，降低NO_x排放，将原有的进气旁通系统改造为EGR系统，使用GT-POWER模型求解出3 000 r/min、60 mg进气量工况下废气入射管道以及进排气道的边界条件和初始条件，并将这些条件导入发动机的CONVERGE模型中进行计算，通过对比不同废气入射管径、不同安装角度、不同安装距离条件下的缸内流动特性、缸内速度场以及缸内废气质量分数分布，确定了最佳废气入射管道参数。结果表明：在3 000 r/min、60 mg进气量工况下，当废气入射管径为5 mm，入射角度为17.5°，安装距离为22 mm时，气缸内能实现EGR分层。

To realize exhaust gas recirculation (EGR) stratification in the cylinder of a motorcycle gasoline engine, so as to reduce pump air loss and NO_x emission, the intake bypass system in the original engine was transformed into an EGR system. The boundary conditions and initial conditions of the exhaust incident pipe, inlet and exhaust ducts under 3 000 r/min and 60 mg intake air were solved by using the GT-POWER model. These conditions were imported into the CONVERGE model of the engine for calculation, and the exhaust gas incident pipe parameters were determined by comparing the flow characteristics, velocity field and exhaust gas mass fraction in the cylinder under different exhaust gas incident pipe diameters, installation angles and installation distances. The results show that under the condition of 3 000 r/min and 60 mg intake air, EGR stratification can be realized in the cylinder when the exhaust gas incident pipe diameter is 5 mm, the incident pipe inclination angle is 17.5° and the installation distance is 22 mm.

TK413.4

重庆市研究生科研创新项目（CYS20017）；重庆市技术创新与应用发展专项面上项目(cstc2019jscx-msxmX0016)。