NUMERICAL INVESTIGATION OF THE EFFECTS OF AIR/FUEL RATIO ON COMBUSTION IN A SPARK IGNITION ENGINE

Abstract

Combustion is one of the main research areas of internal combustion engines. To reduce the air pollution from internal combustion engines, it is required to increase combustion efficiency. In this study, effects of air/fuel ratio were investigated numerically. An axisymmetrical internal combustion engine was modeled in order to simulate in-cylinder engine flow and combustion. Two dimensional transient continuity, momentum, turbulence, energy and combustion equations were solved. k-e turbulence model was employed. Fuel mass fraction transport equation was used for modeling of the combustion. For this purpose a computational fluid dynamics code was developed by using finite volume method with using FORTRAN programming code. The moving mesh was utilized to simulate the piston motion. The code developed simulates four strokes of engine continuously. In the case of laminar flow combustion, Arrhenius type combustion equations were employed. In the case of turbulent flow combustion eddy break-up model was employed