Use of Advanced Tools for the Analysis of Gasoline Direct Injection Engines

Abstract : A methodology that uses simultaneously three dimensional (3D) calculations and advanced experimental tools has been developed in order to characterize air/fuel mixing and combustion of gasoline direct injection (GDI) engines at every stage of development. The experimental tools used in this analysis underline the great cycle-to-cycle variability and show that the air/fuel ratio variations at spark plug are closely linked to the fluctuations of combustion starting and development. Despite this variability, average measurements are reproducible and in good agreement with 3D computational results obtained with KIVA-MB code. The common use of both kinds of tools allows getting a very fine understanding of GDI engine concepts. This approach has been first applied to the analysis of wall-guided direct injection engine concept, through the analysis of Mitsubishi GDI engine. It has also been used for the analysis of the spray-guided direct injection engine concept. In both cases the robustness of the air/fuel ratio control at spark plug is clearly the greatest challenge for GDI stratified engines.