Numerical simulation for effect of fuel injector parameters on combustion and NOx emissions of STC diesel engine

A numerical simulation model for the sequential turbo charging (STC) diesel engine was established by STAR-CD and the initial boundary condition of the model was calculated by the GT-POWER. The experiment results were compared to multi-dimensional model results. Based on the model, the effects on the combustion process and the NO_x emissions, including inject cone angle and inject timing were studied. The model results showed that the inject timing and the inject cone angle played an important role during the combustion process and NO_x emissions characteristic. The larger inject cone angle will increase the mean pressure and temperature of the cylinder, at the same time the NO_x emissions increased relatively. If the larger inject timing was too small also caused engine overheating and the NO_x emissions increased. Therefore, the inject timing and the inject cone angle should be appropriate selected.