关键词: 双燃料燃烧；高速摄影；掺混比例；可视化研究

Abstract: 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 lowtemperature combustion.

Key words: Dual fuel combustion; High-speed photograph; Blending ratio; Optical investigation