喷油策略和缸内流动对汽油机HCCI缸内燃油分布的影响

缸内燃油分层是改善HCCI燃烧控制的常用方法,为了解决燃油分层的控制问题,应用激光诱导荧光法研究了气道喷射和缸内直接喷射的缸内燃油分布,同时结合粒子图像测速技术分析了缸内流场对缸内燃油分布的影响.测量结果表明,气道喷射时缸内燃油分布较为均匀,难以形成燃油分层.而缸内直接喷射形成的燃油分层较为明显,且涡流流场测量结果表明,进气涡流对浓区位置分布有明显引导作用.同时采用缸内直喷时燃油的不均匀度的循环变动要比气道喷射的大,且随着缸内直喷喷油时刻的推迟,不均匀度的循环变动增大.

Effects of Injection Strategy and In-Cylinder Flow on Fuel Distribution in HCCI Gasoline Engine

In-cylinder fuel stratification is often used to improve HCCI combustion control,to solve the problem of fuel stratification control,the research on in-cylinder fuel distribution with port fuel injection and gasoline direct injection was carried out through laser induced fluorescence,and the effects of incylinder flow field on fuel distribution were investigated by using particle image velocity.The results show that the fuel distribution is nearly homogeneous with PFI injection system and it is difficult to form fuel stratification.It is found that the fuel stratification formed by GDI injection is obvious.The swirl flow field results show that intake swirl is strongly correlated with the position of fuel rich area.The cyclic variation of fuel inhomogeneity with GDI injection is greater than that with PFI injection,and when the injection timing is retarded,cyclic variation becomes higher.