NUMERICAL ESTIMATION OF SWIRL AND TUMBLE NUMBERS IN RICARDO RESEARCH ENGINE CYLINDER FOR VARIABLE VALVE LIFTS

Abstract

The turbulence is one of the most important parameters for internal combustion engines. Enough turbulence formations will result in a better mixing process of air and fuel and it will also enhance flame development. The desired turbulent character can be obtained with a well designed intake port. In this study, swirl and tumble motion investigations were performed for Ricardo E6 Research Engine. The CAD model of the engine cylinder with only intake port and intake valve was prepared and imported to STAR- CCM+ v6.04 software. The energy solver was frozen and segregated solver was used during the solutions. The turbulence model selection was a key point for such an analysis. So, three turbulence models (Realizable k-s, k-ro-SST and LES) were compared. The k-s model was found more suitable and stable for these cases. In our investigation, there were two case studies. One of them was effect of valve lift change on swirl and tumble number while the engine was operated constant speed. The second one was effect of engine speed on swirl and tumble number for a unique valve lift. As it is expected for a gasoline engine, the tumble numbers remain higher than swirl numbers. The valve lift change results showed that while increasing of valve lift increased the swirl numbers but decreased the tumble numbers. This inversely proportional result arises from the momentum transform between the angular and axial motions. Anyway, both dimensionless numbers were increased with the engine speed increasing and it was seen that the engine speed is the most effective parameter for incylinder flow formation

Keywords

• Ricardo Engine, Swirl and Tumble Number, CFD Simulation