Integrated flow model with combustion and emission model for VVT Diesel engine

Autoren

Qirui Yang, Michael Bargende, Michael Grill, IVK (Universität Stuttgart), FKFS

Jahr

2019

Zusammenfassung

In this work, a previously developed quasi-dimensional charge motion and turbulence model for the diesel engines with a fully variable valve train [4] is at first extended by enclosing injection effects and modeling internal exhaust gas recirculation (iEGR). Direct injection contributes to the immense generation of turbulence but also affects adversely swirl flows, for which it is modeled both as immediate partial conversion of injection kinetic energy into turbulent kinetic energy (TKE) and as an additional moment of inertia that decelerates swirl. In order to cope with the future application of iEGR, the variability on the exhaust side is taken into account. As indicated by the measurements on the engine test bench, both exhaust valves are handled separately so as to maintain suitable swirl intensity and thereby achieve minimized emissions. The completed flow model is subsequently coupled with a phenomenological combustion model as well as with a phenomenological emission model. Necessary adjustments are made to the models by integrating a swirl term to determine different rates of air entrainment and diffusion combustion. Newly added swirl effects along with better estimated turbulence level assure more precise prediction of heat release as well as emission states.

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