掺混比例对双燃料燃烧影响的可视化研究

Optical Investigation of the Effects of Blending Ratio on Dual fuel Combustion

汽柴油双燃料燃烧模式可以降低柴油机中小负荷的氮氧化物和碳烟排放并提高有效效率。文章在一台光学发动机上,采用高速摄影的方法对汽柴油均质混合气引燃(HCII)燃烧进行了解析,针对汽油比例对HCII燃烧的影响开展了可视化研究。研究结果表明,HCII燃烧的过程是火焰首先随着柴油喷束从汽缸中央向四周延展,同时点燃周围的汽油混合气产生蓝色火焰,蓝色火焰逐渐发展至整个燃烧室范围。汽油火焰在多点被同时点燃,火焰面积在极短时间内迅速增加,覆盖几乎所有缸内范围,相对于传统汽油机,HCII燃烧速度明显增加。随着汽油比例的增加,缸内蓝色火焰比例明显增加,火焰亮度降低,从而实现低温燃烧。

The gasoline-diesel dual fuel combustion mode can reduce the nitrogen oxide and particulate matter emissions of diesel engine and improve the effective efficiency.The gasoline-diesel homogeneous charge induced ignition(HCII)combustion is studied using the high-speed photograph method on an optical engine and the effects of blending ratio on HCII combustion is investigated optically.The results of the study show that the combustion process of HCII started with the flame propagation from the center of the cylinder to the edge with the diesel fuel sprays,igniting the surrounding gasoline mixture.Blue flames are generated and then occupied the entire combustion chamber.The gasoline mixture is ignited at multi-points and the flame area increased rapidly covering almost all the combustion chamber.Compared with conventional gasoline engines,the flame speed of HCII increased obviously.With the increase of gasoline blending ratio,the blue flame ratio in the cylinder increased and the flame brightness decreased obviously resulting in low-temperature combustion.