增压气道喷射发动机PN排放生成机理研究-AVL.PDFVIP

2017 AVL 先进模拟技术中国用户大会论文 增压气道喷射发动机PN 排放生成机理研究 凌鑫晨，李学伟，曹波，陈凯，陶鸿莹 (泛亚汽车技术中心有限公司，龙东大道3999 号，上海，201201) [摘要] 为满足国六排放法规对颗粒物排放数量的要求，从整车WLTC 循环排放，发动机台架试 验及缸内过程数值模拟三个方面，系统地研究了增压气道喷射汽油机 PN 排放的生成机理。整 车循环测试结果表明：在WLTC 循环下前 50 秒产生的PN 排放占总量的44% 以上；台架测试 结果表明：相同工况下，冷态 PN 排放比热态要高出数十倍，并且发动机负荷越高 PN 排放也 越高；AVL_FIRE 软件对缸内过程数值模拟的结果表明：PN 排放与缸内参与燃烧的油膜量有 一定关系，油膜质量越大 PN 排放越高，并且发动机冷热状态、发动机负荷是影响燃油蒸发及 油膜形成的最主要因素。 关键词：PN 排放；WLTC 循环；缸内油膜；数值计算 主要软件：AVL FIRE Research on Formation Mechanism of PN Emissions for a Turbo Charged Port Fuel Injection Engine Xinchen Ling, Xuewei Li, Bo Cao, Kai Chen, Hongying Tao （Pan Asia Technical Automotive Center Co. Ltd ， NO.3999, Longdong Avenue, Shanghai, 201201, China） [Abstract] In order to satisfy PN emission limit of the new legislation, emission formation mechanism was focused. Vehicle test under WLTC cycle, engine test bench research and numerical simulation were carried out to investigate the formation mechanism of PN emission for a turbo charged PFI engine. First of all, test results of the WLTC cycle showed that most PN emitted under cold start conditions and more than 44% PN was emitted at first 50 seconds. Then, engine bench tests indicated that PN emission under cold conditions is tens and hundreds times higher than that of hot conditions. Also, higher engine BMEP caused higher PN. Finally, numerical simulations were carried out through AVL_FIRE. CFD results showed that PN emission had close relationship with in-cylinder wall-film that combusted. Greater amount of in-cylinder wall-film always led to higher PN emission. Moreover, according to the simulation the cold state of engine, as well as the high engine load, had the most significant impact on the fuel evaporation and wall-film formation. Keywords: PN emission; WLTC test cycle; in-cylinder wall-film; numerical simulation Softwa