IN-CYLINDER FLOW ANALYSIS FOR A DIRECT INJECTION DIESEL ENGINE – A CFD APPROACH

A parametric study of the effect of piston bowl configuration on air motion of a direct injection diesel engine motored at 3000 rpm is investigated. Two piston bowl configurations (Mexican-hat and Re-entrant) are modeled for the computational flow analysis. The flow characteristics of these engine bowls are examined under transient conditions using STAR CD, a commercial computational fluid dynamics package. The predicted computational fluid dynamics results of mean swirl velocity of the engine at different locations inside the combustion chamber, at the end of compression stroke were compared with experimental results available in the literature. The results obtained showed very good agreement with the measured data given in the literature. This paper discusses the predicted flow structure inside the combustion chamber at top dead center, with different piston bowl shapes at 3000 rpm. It also compares the radial distribution of mean swirl velocity component in the piston bowl for the two cases. It is observed that the Re-entrant bowl provides a higher swirl ratio at almost all locations than the Mexican hat bowl.