\r陈 锐¹，董 凯¹，宫 雨²，梁俊洁²，李 岩²，卫海桥¹，周 磊¹，华剑雄¹

AuthorsHTML:\r陈 锐¹，董 凯¹，宫 雨²，梁俊洁²，李 岩²，卫海桥¹，周 磊¹，华剑雄¹

AuthorsListE:\rChen Rui¹，Dong Kai ¹，Gong Yu²，Liang Junjie²，Li Yan²，Wei Haiqiao¹，Zhou Lei¹，Hua Jianxiong¹


AuthorsHTMLE:\rChen Rui¹，Dong Kai ¹，Gong Yu²，Liang Junjie²，Li Yan²，Wei Haiqiao¹，Zhou Lei¹，Hua Jianxiong¹


Unit:\r1. 天津大学内燃机燃烧学国家重点实验室，天津 300072；
2. 北京动力总成有限公司技术中心，北京 101106



Unit_EngLish:\r1. State Key Laboratory of Engines，Tianjin University，Tianjin 300072，China；
2. Technical Center，BAIC Motor Powertrain Co.，Ltd，Beijing 101106，China


Abstract_Chinese:\r火花辅助压燃(SACI)是一种由火焰传播诱导未燃混合气自燃的新型燃烧方式．但SACI 爆震现象限制了热效率的进一步提升．针对这一问题，基于一台高压缩比缸内直喷汽油机，首先对SACI 燃烧及爆震界定进行了分析；然后开展了二次喷射策略对SACI 燃烧及爆震特性影响的试验研究．结果表明：火花点火是SACI 燃烧的一个重要环节，点火过于提前会导致SACI 爆震的产生．SACI 爆震的压力振荡幅值(MAPO)要高于SI 爆震且分布更加离散．二次喷射在燃烧室内可以形成不同的燃油浓度分层，对SACI 有良好的爆震抑制效果．当采用喷射比例4∶1、一次喷射时刻300°,CA BTDC、二次喷射时刻140°,CA BTDC 时，通过对爆震的抑制获得最优燃烧特性，循环变动系数降低了1.18%,，有效燃油消耗率降低了约3.11%，有效热效率提高了1.05%．


Abstract_English:\rSpark assisted compression ignition(SACI)is a new combustion mode by inducing the auto-ignition of unburned mixture with flame propagation. However，the knock of SACI limits the increase of thermal efficiency. In this work，the combustion characteristics and knock detection of SACI were analyzed based on a gasoline direct injection(GDI)engine with high compression ratio. Besides，experiments were conducted to investigate the effects of split injection strategy on the combustion and knocking characteristics. The results show that the ignition timing is an essential factor influencing the knock occurrence. Engine knock is easily induced under SACI with excessive ignition advance. When the knock occurs，the maximum amplitude of pressure oscillation(MAPO)under SACI mode is more discrete and higher than that under the SI mode. Split injection can cause different levels of fuel concentration stratification in combustion chamber，which can suppress the engine knock efficiently. The optimal combustion characteristic is obtained through the improved knock resistance at an injection ratio of 4∶1,with an first start of injection(SOI)of 300°,CA BTDC and second SOI of 140°,CA BTDC. In this case，the coefficient of variation and the brake specified fuel consumption decrease by 1.18%, and 3.11%, respectively，the effective thermal efficiency increases by 1.05%,.


Keyword_Chinese:火花辅助压燃；二次喷射；爆震；压力振荡


Keywords_English:spark assisted compression ignition(SACI)；split injection；knock；pressure oscillation



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