Active Control of Cylinder Charge Motion Using Vortex Generating Jets (VGJs) on Generic Intake Port Geometries

摘要

Swirl is known to have impact on the combustion process and the engine emission performance. Generally the swirl flows are generated on engines by e.g. helical or tangential intake ports. However, such features of intake ports constrict the airflow, resulting in raising pumping losses and thus higher fuel consumption. This article introduces a further possibility to generate and regulate the swirl flow by injecting air directly into the intake ports using Vortex Generating Jets (VGJs). The effect of air injection was studied by means of experimental investigations regarding swirl generation and flow rate improvement. The optimization of VGJ diameters, positions as well as injection airflow rate was carried out with respect to energy efficiency of swirl generation. A new methodology for constructing generic intake ports was developed which specifies realistic intake port geometries with about 20 parameters and enables the derivation of comparable intake ports of desirable characteristics. By using this methodology, one set of generic intake ports was built which has a significant helical form and shows accordingly strong swirl ratios (referred to as "ref-ports"). Based on its geometries, a second set of intake ports (referred to as "jet-ports") was derived that has a less helical form and shows therefore reduced swirl ratios but larger flow rates. The swirl intensity of the jet-ports was then enhanced by VGJs. The experiments show that the VGJs on the jet-ports can raise the swirl ratio to the level of the ref-ports, while the flow rates can be further improved by air injection in a certain airflow range. The influence of air injection on engine operations has been analyzed by means of a 1-D engine simulation. The results show the possibility, as well as the potential of VGJs in view of improving fuel consumption and introducing more variability for charge motion control.