Abstract
This study aims at improving understanding of the relation between smoke-reduction effect of post injection and design and operating conditions in small diesel engines. A series of experiments was conducted using a single-cylinder diesel engine under a fixed NOx emission condition to investigate the smoke reduction effect of post injection varying the number of injection nozzle orifice and piston bowl diameter, which would influence the interaction between main spray flames and post sprays. The results indicate that the larger number of nozzle orifice with smaller diameter reduces smoke emissions under late post injection conditions. Advanced post injection reduces smoke emissions for the smaller piston bowl diameter; while retarded post injection reduces smoke emissions for the larger piston bowl diameter. Explanations for these trends were attempted paying attention to the influence of the main spray flames on post sprays.
