Air Motion Inside a Gasoline Engine Cylinder

The engine combustion is one of the most important processes affecting performance and emissions of a SI engine. As the flame propagation slows down due to EGR or lean mixture operation the fast burn system is getting more attention to improve engine performance. One effective way to achieve the fast burn is to control the motion of the charge inside a cylinder by means of optimum intake port design. Various intake ports were designed and tested in this study under several strengths of swirl levels measured by a swirl meter or LDV. Also the swirl and turbulence characteristics influenced by piston motion during intake process were analyzed by measuring cylinder gas motion under engine motoring. The mashed shroud head (MSH) out of five intake ports tested in this study was proved to be the highest swirl generating port while maintaining satisfactory volumetric efficiency. The high intensity swirl generated by the MSH port during the intake process also produces high level of turbulence in the flow caused by shearing action against cylinder wall.