通用小型汽油机进排气系统对缸内污染物生成的影响

Effect of Intake and Exhaust System on Pollutants of Universal Small Gasoline Engine

通过三维流体力学数值模拟的方法解析158F四冲程通用小型汽油机进排气系统对缸内污染物生成的影响,首先对158F四冲程通用小型汽油机进行逆向扫描建模与面网格划分,然后利用流体力学软件CONVERGE对缸内污染物生成情况进行模拟研究,根据试验数据设置模拟计算边界条件,进行燃烧模型参数标定。为了减少此款通用小型汽油机缸内污染物生成量,满足国际排放法规要求,对其方形进气道及涡流排气道进行改进。优化结果表明:30°滚流进气道进气顺畅,缸内压缩行程湍流较强,降低了缸内燃烧温度,减少了NOx的生成量;将涡流排气道修改为直排排气道后,缸内废气能够快速排出,且新鲜混合气迅速充入气缸,缸内残余废气减少,有利于缸内混合气充分均匀燃烧,降低了缸内燃烧温度,减少了NOx及HC的生成量。

Through the method of numerical simulation of three-dimensional fluid dynamics,the influence of intake and exhaust system on the in cylinder pollutant generation of a 4-stroke 158F small petrol engine was analyzed.Firstly,the engine was scanned for reverse modeling and surface meshing,then the commercial software CONVERGE was used to simulate and study the pollutants generated in cylinder.The boundary conditions were set as per the experimental data,and the parameters of the combustion model were calibrated.To reduce pollutants generated in the cylinder of this small gasoline engine and meet the requirements of international emission regulations,the square inlet and eddy exhaust vent were improved.The optimization results showed that the 30°roll flow inlet is smooth,and the turbulence is strong in compression stage,which reduced the combustion temperature in the cylinder and the NO_(x) generation.After the vortex exhaust port was changed to a straight exhaust port,the exhaust gas in the cylinder can be discharged quickly,and the fresh mixture was quickly charged into the cylinder,and the residual exhaust gas in the cylinder was reduced,which was conducive to the full and uniform combustion of the mixture in the cylinder,and the combustion temperature in the cylinder was reduced,and the generation of NO_(x) and HC was reduced.