Rolf D. Reitz

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Non-equilibrium turbulence considerations from rapid distortion theory have been utilized to derive a correction to the turbulence dissipation rate, which then has been implemented in combination with the RNG k-epsilon model in a KIVA-based code. This correction reflects the time delay between changes in the turbulent kinetic energy due to changes in the(More)
Engine experiments have shown that with highpressure multiple injections (two or more injection pulses per power cycle), the soot-NOx trade-off curves of a diesel engine can be shifted closer to the origin than those with the conventional single-pulse injections, reducing both soot and NOx emissions significantly. In order to understand the mechanism of(More)
A new combustion model is developed and applied to simulate combustion in dual-fuel engines in which the premixed natural gas is ignited by the combustion flame initiated by a diesel spray. The model consists of a diesel auto-ignition model and a flame propagation model. A G-equation model previously developed to simulate SI engine combustion was(More)
A new model to predict spray-tip penetration for a time-varying injection profile has been formulated based on gasjet theory. The approach involves using an effective injection velocity for the spray tip based on a representative spray response time. It is assumed that the instantaneous injection velocity affects the spray tip with an exponential response(More)
The purpose of this paper is to compare the drop sizing results of an Aerometrics phase/Doppler particle analyzer with those of a Malvern laser-diffraction instrument. Measurements were performed on a small pressure-swirl atomizer. Since the laser-diffraction instrument measures a line-of-sight average through different regions of the spray while the(More)
A next-generation spray and atomization model for high-pressure diesel sprays has been developed and implemented into an engine computational fluid dynamics (CFD) code (KIVA-3V), together with a nozzle flow cavitation model and an evaporation model for the Eulerian liquid phase. In contrast to the widely used Lagrangian atomization models that are based on(More)
A computational optimization study is performed for a heavy{duty direct{injection diesel engine using the recently developed KIVA{GA computer code. KIVA{GA performs full cycle engine simulations within the framework of a Genetic Algorithm (GA) global optimization code. Genetic Algorithms are arti cial intelligence techniques which employ the processes of(More)
Detailed chemistry was used with engine CFD code for HCCI engine combustion modeling in order to achieve a more accurate analysis. The present study improved the computational efficiency by using reduced mechanisms and parallel computing schemes. In the reduced mechanism, the number of species and reactions were reduced using a systematic approach by the(More)
A computer model developed for describing multicomponent fuel vaporization, and ignition in diesel engines has been applied in this study to understand cold-starting and the parameters that are of significant influence on this phenomena. This research utilizes recent improvements in spray vaporization and combustion models that have been implemented in the(More)