Numerical Investigation of Split Injection Strategy on Performance and Emission Characteristics of Diesel Engine

Abstract

The present work investigates the effect of split injection and piston bowl geometry on engine performance and emission. A numerical investigation is performed on a single-cylinder DI Diesel engine using AVL FIRE code. Six different configurations of piston bowl along with three injection ratios were considered. The piston bowl geometry is modified by varying the depth and bowl radius keeping bowl volume, compression ratio, engine speed and mass injected invariant. It was noted that the mass of fuel injected as pilot injection got mixed with the air and the mixture became ready for burning prior to the occurrence of the main injection. In addition to this, the role of increasing the pilot injection mass up to 15% along with piston bowl geometry on the in-cylinder mean pressure, temperature, rate of heat release and emission parameter is explored. Further, an optimization study is undertaken for selected eighteen cases and results were evaluated for different injection ratio and piston geometry. The D4R1 cases were found to be optimum on the basis of emission and performance characteristics as it results in the reduction of soot to 16% and NO to 10% compared with single injection.