A CFD Study of a 4-Valved, Fuel Injected Two-Stroke Spark Ignition Engine

The CFD code KIVA is used in conjunction with a one-dimensional wave action program to simulate exhaust blowdown, in a study of the scavenging and combustion at different loads and constant engine speed, in a single cylinder 4 valved 2-stroke engine configuration, using in-cylinder fuel injection. Two combustion chamber geometries -- a stepped head and a pentroof, were used in this study. The stepped head geometry has a combustion chamber recessed in the cylinder head, and contains the intake valves. The vertical intake port configuration provides a well developed reversed loop flow in the engine cylinder. The pentroof combustion chamber is similar to those used in current 4 stroke engines(1)*.

The computational study focuses on the effects of injector orientation, and the subsequent interaction between the fuel spray and ‘loop swirl’ of air in the engine cylinder, and on the resulting combustion characteristics and exhaust emissions. The effect of varying inlet and exhaust valve timing on the scavenging process and combustion have also been studied.