Characteristics of fuel evaporation, mixture formation and combustion of 2D cavity impinging spray under high-pressure split injection

The objective of this study is to obtain an enhanced understanding of the effect of split injection on the mixture formation and combustion processes of diesel spray. The study focused on the evaporation, mixture, and combustion of diesel fuel under 2D piston cavity sprays with split injection strategies in a constant volume combustion chamber. Three injection strategies with injection pressures of 100 MPa and 160 MPa, respectively, and a single nozzle hole with a diameter of 0.111 mm were employed. The tracer Laser Absorption Scattering (LAS) technique was used to visualize the spray mixture formation process. High speed imaging of OH∗ chemiluminescence and the two-color method were used to visualize the instantaneous spray combustion process. The experimental results reveal that the vapor distribution of the split main injection with a high injection pressure was more homogeneous than that of a single main injection with low injection pressure at the end of injection (EOI). The split injection can decrease the soot mass. Ignition is more easily during the main injection as a result of the pre-injection. High soot concentration appeared near the cavity wall region under the three injection strategies. The results also indicate that the split injection accelerates the soot oxidation process during the post combustion period.