Effect of the dwell angle of split injection in a single-cylinder optical diesel engine

Abstract

This study investigates the effects of split-injection strategies with high levels of exhaust gas recirculation on the combustion performance and emissions in a single-cylinder direct-injection optical diesel engine. The engine is equipped with high-pressure common-rail fuel injection and designed to provide optical access through the piston window and side windows. The experiments were carried out at a relatively high engine speed of 2000r/min for an optical engine and in-cylinder conditions matched to a multiple-cylinder engine through boost and intake charge heating. High-speed combustion imaging, two-colour temperature, and soot concentration measurements were carried out in conjunction with in-cylinder pressure and heat release analysis and exhaust emissions. The results at two dwell angles and different injection timings are presented and analysed in this paper. The effects of the dwell angle and fuel injection timings on fuel air mixing, combustion, soot formation, and emission are identified and discussed.