Evaluation of Scavenging Performance in a Novel Two-Stroke GDI Engine

CFD simulations of the transient, three-dimensional scavenging process in a novel two-stroke gasoline direct-injection (GDI) engine were performed for a variety of engine speeds and intake pressures. The simulations entail the modeling of fresh intake air flow through a set of intake ports distributed over the cylinder head, which in turn mixes with and displaces the combustion products out through exhaust ports located at the bottom of the cylinder. Global engine performance characteristics such as scavenging efficiency as a function of crank angle and delivery ratio are quantified. Furthermore, sources of short-circuiting of the fresh air charge as well as pockets of exhaust gas recirculation are identified within the engine cylinder during the course of the scavenging process.