汽油压燃小负荷燃烧过程优化  

Gasoline Compression Ignition Low-Load Combustion Optimization Based on Double Exhaust Valve Opening and Injection Strategy

作　　者：祝宇轩 王浒[1] 张翔宇[1] 童来会[1] 冯浩[1] 尧命发[1] Zhu Yuxuan Wang Hu Zhang Xiangyu Tong Laihui Feng Hao Yao Mingfa(State Key Laboratory of Engines, Tianjin University, Tianjin 300072, Chin)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《内燃机学报》2016年第5期415-422,共8页Transactions of Csice

基　　金：国家自然科学基金资助项目(51576138)

摘　　要：利用三维计算流体力学软件CONVERGE,通过数值模拟方法,系统研究了内部EGR和喷油策略的耦合控制对汽油压燃(GCI)燃烧模式小负荷燃烧的影响.结果表明:采用排气门两次开启策略引入内部EGR后,缸内温度得到显著提高;在平均指示压力p_i为0.32,MPa的工况下,与单次喷射相比,采用两次喷射可以有效控制缸内混合气分布,提升缸内混合气浓区和高温区的一致性,进而显著提高燃烧效率和指示热效率;随着负荷降低,燃烧效率和指示热效率有所下降,需要提高内部EGR率和进气压力以保持较好的燃烧特性;在pi约为0.22,MPa的工况下,单次喷射的燃烧效率较两次喷射更高,即随着GCI负荷的降低,喷油策略应由两次喷射变为单次喷射以控制缸内混合气分布,从而使燃烧得到改善.Numerical simulations were conducted with 3-dimentional computational fluid dynamic （CFD）software CONVERGE to investigate the effects of internal EGR combining with injection strategy on the combustion of gaso- line compression ignition （GCI）at low loads. Results show that temperature is improved greatly by double exhaust valve opening strategy. At 0.32 MPa gross IMEP, the double injection strategy can improve the regional consistency between high equivalence ratio and high temperature regions, thus improves combustion efficiency and indicated thermal efficiency through mixture distribution optimization compared with single injection strategy. As combustion efficiency and indicated thermal efficiency will decrease with load decreasing, it is necessary to increase the internal EGR rate and intake pressure to maintain acceptable combustion. At 0.22 MPa gross IMEP, single injection strategy shows higher combustion efficiency than double injection. Therefore, with the increase of load, the single injection strategy should be adopted to enhance the auto-ignition and combustion through mixture distribution optimization and control.

关 键 词：汽油压燃 小负荷 内部EGR 喷油策略 

分 类 号：TK412.2[动力工程及工程热物理—动力机械及工程]