Effects of injection strategies on the flow and fuel behavior characteristics in port dual injection engine

The port dual injection (PDI) technology is proposed to improve the fuel efficiency and emission characteristics of the downsized SI engine by adding an injector to the intake port. For effective design of the PDI engine, the effects of additional design parameters on the engine performance due to the added injector should be taken in to account. In this study, we analyze the effects of the fuel injection timing and injection targeting related to the injection strategies of the PDI engine on the internal flow and fuel behavior characteristics using computational fluid dynamics (CFD). The CFD analysis is conducted using the STAR-CD, a three-dimensional unsteady simulation program. To confirm the accuracy of CFD analysis, the experimental verification is carried out. The liquid fuel films, evaporated fuel and air-fuel mixture uniformity affecting the fuel efficiency and emissions of the engine are analyzed at various injection conditions. It is concluded that the fuel film amount decreases by approximately 73.04% compared to the standard injection method when the engine is operated at the optimum conditions selected in this study.