Effects of injection timing, before and after top dead center on the propulsion and power in a diesel engine

Abstract

It is well known that injection strategies including the injection timing and pressure play the most important role in determining engine performance, especially in pollutant emissions. However, the injection timing and pressure quantitatively affect the performance of diesel engine with a turbo charger are not well understood. In this paper, the fire computational fluid dynamics (CFD) code with an improved spray model has been used to simulate the spray and combustion processes of diesel with early and late injection timings and six different injection pressure (from 275bar to 1000bar). It has been concluded that the use of early injection provides lower soot and higher NOx emissions than the late injection. In this study, it has been tried using the change of fuel injection time at these two next steps: before top dead center (BTDC) and after top dead center (ATDC) in order to achieving optimum emission and power in a specific point.