Effect of air injection before compression on pressure oscillation in high load HCCI combustion

Abstract

The HCCI engine, which is expected to be the combustion method for next-generation automobile engines, has a problem that strong pressure oscillation is generated under high load condition. From previous studies, this pressure oscillation was greatly reduced by a small amount of air injection before compression. It was considered that this was because the spatial distribution of ignition delay was formed in the combustion chamber cylinder after compression due to the difference in the specific heat ratio of air and fuel premixture. In this study, we investigated the effect of the injection pressure and the injection duration on pressure oscillation intensity under higher load conditions where the equivalence ratio is close to unity.