Characteristics of Diesel Combustion and Emissions with a Multi-injector System

A conventional single cylinder direct injection diesel engine was fitted with three fuel injectors: one mounted vertically on the center, and the others mounted diagonally from the side direction. With this system, it was possible to control the fuel injection timing and injection quantity of each injector independently. It was also possible to independently control the fuel injection pressure of the center and side injectors. Using this system, it was possible to control the spatial and temporal distributions of the fuel injected into the combustion chamber, which are impossible to obtain with conventional injection equipment.

In this study, an improvement in particulates and specific fuel consumption was obtained, while maintaining low NOx, by injecting a small amount of fuel from the two side injectors after the main fuel injection from the center injector. Measurements were made in order to characterize engine performance and emissions, as influenced by the spatial fuel distribution inside the combustion chamber, by changing the relative fuel injection direction of the center and side injectors. Split fuel injection was also tested using all three injectors with a total of six injections during one cycle, which resulted in sharply decreased particulates but worsened specific fuel consumption.