418 Fuel Spray Behavior in a Small DI Diesel Engine under Reverse Squish

Abstract

Modern small DI diesel engines are operated at high loads and high speeds. In these engines at the end of impingement much of the spray is carried to the cavity outside by strong reverse squish when the injection timing is retarded. This causes flame quenching, and higher HC and PM emission. In this study the fuel spray development under reverse squish was investigated in a small direct injection diesel engine with a common rail injection system. It was found that the roundness at the top and bottom side of lip causes leakage of fuel to outside the cavity during the expansion stroke when the charging pressure is high.