A numerical study on the soot and combustion performance of a diesel engine with pip shape

The shape of the combustion chamber plays an important role in the formation of the air-fuel mixture in the chamber, which has a great influence on the combustion efficiency and emission formation. The pip is a protruding shape at the center of the combustion chamber, and its importance has been evaluated to be relatively low. There has also been little research on off-highway diesel engines in comparison with on-highway diesel engines. When a high-pressure injection system is used in an off-highway diesel engine, which injects more fuel than on-highway engines, the shape of the pip greatly affects the mixture spray momentum and air flow in the combustion chamber. In this study, the pip geometry of a 2.4-liter off-highway engine was modified using three shapes: a step cone, W shape, and egg shape. We used 3-D combustion simulations to analyze the effects of the pip geometry on the mixture formation and combustion efficiency. We also analyzed the influence of the height and corner angle of the pip on the combustion and emission based on the egg shape, which was the most efficient. The results of this study could be used as a guide in designing combustion chambers for diesel engines.