Bitte wählen Sie ihr Lieferland und ihre Kundengruppe
An integrated system of models is presented to evaluate performance and emissions for a SI engine. The models provide steady state data to be used for the development and validation of synthetic engine models in the framework of a hierarchical model structure. The proposed model structure is composed of a commercial code for the 1D modeling of intake and exhaust unsteady gas flow and the simulation of the engine turbulent combustion coupled with quasi dimensional models for the estimation of the in-cylinder thermal gradient and the NOx exhaust emissions. An identification analysis has been performed for the estimation of the optimal parameters of the turbulent combustion model and a polynomial regression has been derived to express their dependence with the engine operating condition. The model structure has been tested vs. a set of 106 experimental data measured on a commercial 4 cylinder SI engine, showing a satisfactory level of agreement between measured and predicted performance and emissions data. Moreover the results evidence that due to the high physical information contents, dimensional and phenomenological models require a limited amount of 15 - 20 measurements for their identification with a drastic reduction of the experimental effort with respect to conventional mapping techniques based on black-box models.