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Ongoing efforts in applying a “high-end” turbulent combustion model (a transported probability density function - tPDF - method) to direct-injection internal combustion engines are discussed. New numerical algorithm and physical modeling issues arise compared to more conventional modeling approaches. These include coupling between Eulerian finite-volume methods and Lagrangian Monte Carlo particle methods, liquid fuel spray/tPDF coupling, and heat transfer. Sensitivity studies are performed and quantitative comparisons are made between model results and experimental measurements in a diesel/PCCI engine. Marked differences are found between tPDF results that account explicitly for turbulence/chemistry interactions (TCI) and results obtained using models that do not account for TCI. Computed pressure and heat release profiles agree well with experimental measurements and respond correctly to variations in engine operating conditions.

Two widely available engine and hybrid electric vehicle (HEV) simulation packages have been integrated to reduce fuel consumption and pollutant emissions for a hybrid electric sport utility vehicle. WAVE, a one-dimensional engine analysis tool available from Ricardo Software, was used to model a 2.5L 103 kW Detroit Diesel engine. This model was validated against engine performance and emissions data obtained from testing in a combustion laboratory. ADVISOR, an HEV simulation software developed by the National Renewable Energy Laboratory in partnership with the Department of Energy (DOE), was used to model a 2002 Ford Explorer that is being converted into an HEV by the Penn State University FutureTruck team. By integrating the output file from WAVE as the input engine data file for ADVISOR, one can predict the effect of changes in engine parameters on vehicle emissions, fuel consumption, and power requirements for specified drive cycles.

A comprehensive modeling and visualization study of flow and combustion is reported for a production four-valve-per-cylinder homogeneous-charge four-stroke-cycle spark-ignited engine. Coupled port and in-cylinder computations are presented for five combinations of valve deactivation, valve shrouding, and cam profile. Motored (induction and compression) results are compared with transient-water-analog flow-structure visualizations. A new flamelet model for homogeneous-charge turbulent premixed combustion has been implemented for fired engine simulations. Several issues in the application of CFD to flow and combustion modeling in practical port-and-cylinder systems are addressed. These include numerical inaccuracy, elucidation of the role of induction-generated flow structure and turbulence, and new insights into premixed flame propagation.