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Three dimensional computational model has been developed to predict the macroscopic behavior of the fuel spray in D. I. diesel engines. The model was based on the KIVA-II code with modification of some submodels that it can deal with the observed phenomena such as liquid column near the nozzle tip and spray impingement on a wall. Firstly, this model was verified by comparing the prediction with the experimental results in a constant volume vessel. Secondly with application to a D.I. diesel engine, the detailed behavior of the spray in a combustion chamber was revealed. Moreover, the engine performance under different spray angles were discussed with the prediction of this model.

A reduced chemical kinetic model of diesel fuel, which can be applied to computational fluid dynamics (CFD) simulation coupled with detailed chemistry using the CONVERGE software, is developed to simulate the particulate matter (PM) formation process. We analyzed the influence of varying intake oxygen concentrations and fuel composition on the polycyclic aromatic hydrocarbons (PAHs) and soot formation processes. When the intake oxygen concentration was decreased, no significant difference was observed in PAH formation associated with soot formation, and the soot mass generated after the peak was high. When the fuel contained high levels of aromatics and naphthene, the PAH and soot formation mass increased. These tendencies were in good agreement with experimental results [1].

To improve the impinging spray's computational fluid dynamics (CFD) calculations under evaporating conditions, a detailed large eddy simulation (LES) code was constructed and examined for modeling the near-wall-velocity behavior of the impinging jet. The near-wall-velocity profile within the impinging jet was found to be different from that obtained using the steady wall functions. On the basis of this knowledge, a simple model of the wall boundary conditions was proposed for the impinging jet. The tests covered two different turbulence models. Comparing with the conventional wall functions, the proposed model improved the accuracy of the impinging spray simulations.