Simulation of Combustion in a Direct Injection Engine with Porous Media

Porous media (PM) combustion has interesting advantages compared with free flame burners due to raised burning rates، increased power ranges، extended lean flammability limits، and reduced pollutant emissions. In future internal combustion engines pollutant emissions and fuel consumption should be minimized under a wide range of speed and loads. These parameters strongly depend on mixture formation and combustion processes which are difficult to control in a conventional engine. This may be achieved by realization of a homogeneous combustion process in engine. This paper deals with the simulation of a direct injection internal combustion engine equipped with a chemically inert PM of hemispherical geometry used to homogenize and stabilize the combustion. A 3D numerical model for PM engine is presented in this study based on a modified version of the KIVA-3V code. Due to lack of any published data about the PM engine، numerical combustion wave propagation in the porous medium were compared with experimental data of methane-air mixture under filtration in a packed bed which showed very good agreement. Methane was injected directly inside the hot PM which was assumed to be mounted on the cylinder head. A lean mixture was formed and volumetric combustion occurred in the PM. The mixture formation، pressure and temperature distribution in both phases of PM and in-cylinder fluid، the production rates of CO and NO، and effect of injection time in the closed part of the cycle were studied.