Application of Optical Techniques to the Study of Mixture Preparation in Direct Injection Gasoline Engines and Validation of a CFD Model

The performance of a direct injection gasoline engine (G-DI) is highly dependent on the quality of the air-fuel mixture preparation. This is of particular importance when operating at a stratified charge condition, where the ideal mixture distribution would be a stoichiometric region around the spark plug, surrounded by air. To achieve this ideal situation over a wide range of speeds and loads is extremely difficult, requiring an understanding of the fuel spray, the in-cylinder air motion and their interactions.

This paper presents the results of Phase Doppler Anemometry (PDA) and Laser Induced Fluorescence (LIF) measurements made both within an optically accessed direct injection gasoline engine and under atmospheric conditions. The experimental results are compared with those of a VECTIS Computational Fluid Dynamics (CFD) simulation of the same engine. A good correlation between experimental data and simulation results means that VECTIS can be used confidently to assess the ability of different G-DI combustion systems to produce a stratified air-fuel mixture.