点火策略对均质稀燃汽油机燃烧特性影响的模拟  

Simulation of the effect of ignition strategies on the combustion characteristics of a gasoline engine with homogenous lean mixtures

作　　者：何邦全[1] 张国伟[1] HE Bangquan;ZHANG Guowei(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学先进内燃动力全国重点实验室,天津300072

出　　处：《武汉大学学报（工学版）》2024年第7期933-940,共8页Engineering Journal of Wuhan University

基　　金：国家自然科学基金项目(编号:52076148)。

摘　　要：利用三维数值模拟方法,在过量空气系数为1.8时,研究了1000、2000 r/min转速下4次点火策略对均质稀燃直喷汽油机着火和火焰传播过程的影响。结果表明:相邻2次点火之间的时间间隔会影响能量耦合形式,并决定汽油机的着火和火焰传播特性。在总点火能量不变的条件下,与单次点火策略相比,4次点火策略的点火耦合加热作用可促进火焰面内可燃混合气的氧化过程,加速火核的发展和火焰传播。在不同转速和负荷下,随着点火间隔的增大,着火时刻先提前后推迟,燃烧持续期先增大后减小,指示平均有效压力(indicated mean effective pressure,IMEP)和指示热效率有同样的变化规律,与单次点火策略相比,采用4次点火策略时,在1000、2000 r/min下IMEP最高可分别增加0.03、0.05 MPa,指示热效率可分别增加3.3%、2.9%。The effects of four-ignition strategy on the onset of combustion and flame propagation of a direct injection(DI)gasoline engine fueled with homogenous lean mixtures were studied with excess air coefficient of 1.8 at speed of 1000 r/min and 2000 r/min by using three-dimensional numerical simulation method.The results show that the time interval between two sequential ignitions affects the energy coupling form and determines the onset of combustion and flame propagation characteristics of the gasoline engine.Under the condition of constant total ignition energy,compared with the single ignition strategy,the coupling heating effect of four-ignition strategy promotes the oxidation processes of the combustible mixture in the flame surface,accelerates the development of flame kernel and flame propagation.At different speeds and loads,with the increase of ignition time interval in the four ignitions,the onset of combustion is first advanced and then delayed,and the combustion duration is first increased and then decreased.In the meantime,indicated mean effective pressure(IMEP)and indicated thermal efficiency follow the same change trend as the combustion duration.Compared with the single ignition strategy,in the four-ignition strategy,the maximum IMEPs can be increased by 0.03 MPa and 0.05 MPa,respectively,while the indicated thermal efficiency can be increased by 3.3%and 2.9%,respectively,at speed of 1000 r/min and 2000 r/min.

关 键 词：汽油机 稀混合气 均质燃烧 多次点火 数值模拟 

分 类 号：TK411.2[动力工程及工程热物理—动力机械及工程]