Problèmes liés à la modélisation de la combustion dans les moteurs à injection directe

Problems due to combustion modelling in direct injection engines

Renault, Direction de la Recherche

Abstract

Turbulent combustion modelling adapted for direct injection engines have to describe partially premixed flame propagation for gasoline engines and diffusion flame for Diesel engines. Moreover, the very specific behaviour of internal combustion engines needs the description of the different stages of flame propagation (ignition, propagation, interaction with walls). For instance, it consists of ignition by a spark for gasoline engines and auto-ignition for Diesel engines. The interaction of chemical reactions and turbulence represents an extremely complex process where numerous phenomena occur. For direct injection engine, an additional difficulty exists due to the presence of fuel droplets in the flame. Finally, the validation of these models necessitates the existence of precise and detailled databases obtained for unsteady, confined configurations.