Auto-ignition Characteristics of Gasoline Sprays with Two-Stage Injection in CI Engines

Abstract

Spray mixing-controlled combustion in a conventional diesel engine has the advantage to enable control of the heat release rate by the fuel injection rate. The low reactivity of gasoline is helpful to ensure for obtaining a flame with an extended set-off length, the distance from the nozzle to the combustion zone, making it possible to enhance air-entrainment in the spray while maintaining the advantages of mixing-controlled combustion. A two-stage fuel injection strategy was employed to control the ignition in the present study, particularly paying attention to the interaction between intermediate species produced by the first injection and the air-fuel mixture supplied by the second injection. The effect of intermediate species was experimentally examined in a single cylinder CI engine and numerically studied by zero-dimensional spray combustion simulation with a detailed reaction mechanism. To learn more details of the effects of the intermediate species, chemical kinetics calculations were conducted by CHEMKIN-PRO.