NUMERICAL INVESTIGATION OF THE COMBUSTION PROCESS IN A DIRECT-INJECTION STRATIFIED CHARGE ENGINE

A numerical study of the turbulent combustion in a direct-injection st ratified charge engine is presented. The focus of the present paper is incorporating detailed reaction schemes as well as coupling the turbu lent flow characteristics to chemical reactions. In the present applic ation most of the combustion occurs in diffusion dames, and the combus tion takes place in the flamelet regime for turbulent combustion. The present model extends the flamelet model for turbulent diffusion flame s to conditions of internal engine combustion. The computations are pe rformed using the KIVA-II code that is modified to include the present combustion model. Results are presented for three different engine lo ad conditions. For comparison, there are numerical integrations with s implified chemistry as well as measurements of both the pressure histo ry and the chemical composition of the exhaust gas. The discrepancies between measurements and calculations with the simplified model are gr eatly improved, for instance, from about 56% to about 19% for the modi fied flamelet model for the mass of CO for the full-load case.