摘要
针对重型发动机汽油压燃(GCI)燃烧模式,采用计算流体动力学(CFD)模拟的方法开展了喷射策略对GCI大负荷拓展影响的研究.在气道喷射结合缸内单次喷射策略下,通过优化EGR率、进气压力、喷射压力和喷射正时等燃烧边界条件,当喷油量为110mg/cyc时,相对未优化工况,可以将平均指示压力(IMEP)从1.868 MPa提升至2.036 MPa,soot排放从0.4700g/(kW·h)降低到0.0200g/(kW·h).在此基础上,进一步研究了气道喷射结合缸内两次喷射策略对GCI大负荷燃烧的影响.结果表明:引入合适比例的气道预混或加入较早的预喷,可以在控制压力升高率的同时获得较低的soot排放(0.0177g/(kW·h))和较高的IMEP(2.056 MPa);相比于气道喷射结合缸内单次喷射、缸内两次喷射的策略,气道喷射结合缸内两次喷射条件下IMEP可以获得进一步改善,分别为0.21%和0.24%,且最大压力升高率均可以控制在1.2 MPa/(°)CA以下,最高缸内压力过高限制了发动机负荷的进一步拓展.
Aiming at the gasoline compression ignition(GCI)combustion mode on a heavy-duty engine,the effects of the injection strategy on the high load expansion of the GCI mode were studied by computational fluid dynam-ics(CFD)simulation.Under the condition of port-injection combined with in-cylinder single injection,the combustion boundary conditions including EGR rate,intake pressure,injection pressure and injection timing were optimized.After optimization,it is found that the indicated mean effective pressure(IMEP)increases from 1.868 MPa to 2.036 MPa and the soot emissions decrease from 0.4700g/(kW·h)to 0.0200g/(kW·h)at 110mg/cyc injec-tion quantity.Based on the above conditions,the effects of port-injection combined with in-cylinder two-injection strategy on GCI combustion at heavy load operation were studied.The results show that a proper proportion of portinjection or early pre-injection leads to a lower soot emissions(0.0177g/(kW·h))and a higher IMEP of 2.056 MPa while maintaining the pressure rise rate.Comparing the strategies of port-injection combined with incylinder single-or two-injection,the IMEP increases by 0.21%and 0.24%respectively under the condition of preinjection combined with in-cylinder two-injection strategy.The maximum pressure rise rate for all three strategies are below 1.2MPa/(°)CA.Further load extension is limited by excessive maximum in-cylinder pressure.
作者
郑尊清
刘威
马桂香
王灿
刘海峰
Zheng Zunqing;Liu Wei;Ma Guixiang;Wang Can;Liu Haifeng(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2021年第4期297-305,共9页
Transactions of Csice
基金
国家自然科学基金资助项目(51976134,91941102).
关键词
汽油压燃
喷射策略
大负荷拓展
排放
gasoline compression ignition(GCI)
injection strategies
high load extension
emissions
作者简介
郑尊清,博士,研究员,E-mail:zhengzunqing@tju.edu.cn;通信作者:刘海峰,博士,教授,E-mail:haifengliu@tju.edu.cn.
