Experimental and numerical investigations of effect of split injection strategies and dwell between injections on combustion and emissions characteristics of a diesel engine

In this work, effects of various split injection strategies and dwell between injections on diesel engine combustion and emissions characteristics have been studied experimentally and numerically using Converge computational fluid dynamics tool. The electronic fuel injection unit, which is capable of injecting fuel up to four injections per cycle, was attached to the engine to achieve various split injection strategies. Results of the study showed that a significant reduction in nitrogen oxides with an acceptable change in particulate matter, hydrocarbons, carbon monoxide and brake thermal efficiency has been achieved with 2-shot:50(-27)-50 split injection strategy with a dwell of 8 crank angle as compared to the single injection strategy. Hence, split injection technique may be considered as an alternative to exhaust gas recirculation technique. Results also showed a fall in premixed heat release peak with an increase in diffusion combustion phase, when the dwell period was increased for all split injection strategies. As a consequence, reduction in nitrogen oxides and increase in particulate matter, hydrocarbons and carbon monoxide were observed with increased dwell between injections. Results of numerical study showed that contour area with higher temperature was observed to be lesser for 2-shot:50(-27)-50 split injection as compared to that for single injection, resulting in reduced nitrogen oxides