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This paper describes a spray impingement model which is formulated on the basis of literature findings and mass, momentum and energy conservation constraints. The model involves the analysis of the relevant impingement regimes and the associated post-impingement characteristics. In order to reflect, to some extent, the stochastic nature of the impingement process, a random procedure is introduced to determine some of the quantities representing the post-impingement status. This allows secondary droplets resulting from splash to have a distribution of sizes and velocities. Numerical simulations for several test cases are presented, showing satisfactory agreement with experimental data.

In this study three-dimensional CFD calculations of the gas motion and spray characteristics of a small (1.9l), high-speed direct-injection Diesel engine are presented and evaluated. The calculations were performed using the SPEED code, developed within the European IDEA-EFFECT project: it uses fully implicit finite volume methodology in conjunction with an unstructured mesh to represent the full complexities of the engine geometry and solve the equations governing the gas motion, fuel spray evolution and subsequent fuel/air mixing. Submodels for particular aspects of these processes developed by various partners in the project are incorporated. The accuracy of the predictions is assessed through comparisons with detailed LDA measurements of the velocity field during the induction and compression strokes up to the time of ignition, as well as with quantitative measurements of the spray penetration and local droplet velocities. Moderately good agreement is obtained.