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Development of an Integrated Spray and Combustion Model for Diesel Simulations
Published September 13, 2000 by CMT in Spain
An integrated multidimensional model has been developed for diesel engine in-cylinder process simulations. The model simulates the fuel spray atomization, ignition, combustion and pollutant formation processes. Fuel spray atomization is modeled by assuming the breakup to be due to the growth of unstable surface waves induced by the relative velocity between the fuel drop and the surrounding air. The ignition models use detailed chemistry on generic species and reactions which describe the low temperature chemistry of hydrocarbon fuels. After ignition, the subsequent combustion process is modeled by considering the combined effects of chemical kinetics and turbulent mixing on fuel oxidation. The NO formation model uses the extended Zeldovich mechanism and the soot production model uses a competitive mechanism between the formation rate and the oxidation rate. The above integrated model has been implemented in both the KIVA and STAR-CD codes for engine simulations. Good agreement was obtained in the in-cylinder pressure, heat release rate and soot-NOx trade-off over a wider range of operating conditions. The model is formulated in a modular library structure for ease of implementation in other engine CFD codes.