Regulations on emissions from diesel engines are becoming more stringent worldwide. Hence there is a great deal of interest in developing engine combustion systems that offer the fuel efficiency of a diesel engine, but with low smoke and NOx emissions. Thus, premixed compression ignition combustion is an interesting way to achieve a clean and efficient engine. However, using a high reactivity fuel such as diesel fuel leads to a complex and expensive engine design. A proven way to overcome this drawback is to actively control the reactivity of the fuel using low cetane fuels such as gasoline. This strategy has been explored with single and multiple cylinder engines. However no detailed and well conducted studies of the injection process were found related to the effects of gasoline use in a standard commercial compression ignition diesel engine injection system.
This paper focuses on an experimental study which compared the effects of diesel fuel and gasoline on injection rate, spray momentum, and mixing behavior under non-evaporative conditions. A parametric study has been performed varying injection pressure, injector energizing time, and chamber back pressure for diesel fuel and gasoline in specific test rigs developed for this purpose.
Compared to diesel fuel, the gasoline fuel results showed lower mass flow and no significant differences in spray momentum when the injector was fully open. Moreover, no relevant changes between the two fuels were found in the macroscopic spray characteristics for non-evaporative conditions. Most of the observed differences are explained by the different fuel properties of the diesel fuel and gasoline. Furthermore, a correlation has been developed for spray tip penetration at different distances from the nozzle exit for both gasoline and diesel fuel.