柴油机瞬态喷雾特性及喷油器后滴油现象试验研究及分析

An Experimental Study of Spray Characteristics of a Diesel and Analyzing of Fuel Dripping Phenomenon

采用高速摄影技术对某型国产喷油器分别在有背压条件和自由喷雾情况下进行了喷雾宏观特性测试,获得了不同喷油压力和背压条件下油束的宏观形态;在高速摄影技术基础上使用长焦显微镜头捕捉到该喷油器喷雾末期的后滴油现象并探究产生此现象的原因。研究结果表明:喷油压力或喷射背压的提高可以显著增加喷雾锥角,增大喷雾场在燃烧室中的分布范围,更有利于油气混合;燃油喷雾过程的喷雾锥角曲线呈明显的双波峰形状;电磁阀阀芯落座的响应时间过长造成喷油器断油不干脆是产生后滴油现象的原因之一。

In order to study the spray characteristics of a certain type of a domestic injector, experimental study on its macroscopic spray characteristics was carried out with and without environmental pressure respectively by using high-speed photography technology. Macroscopic spray forms with different injection pressure and environmental pressure were obtained. Based on this, a fuel dripping phenomenon at the end of the spray was captured by using a telephoto macro lens and the causes of the dripping were analyzed. The study indicates that increasing either injection pressure or environmental pressure can increase spray cone angle evidently and can then expand the scope of spray field in combustion chamber, which is conducive to air-fuel mixture. Spray cone angle against spray process shows a double-peak shape. And slow seating of solenoid valve core resulting in slow close of injection is one of the causes of fuel dripping phenomenon.