Evaluation of the applicability of Zimont's turbulent flame speed closure model to an octane fueled engine with moderate level of turbulent intensity

Abstract

present work aims to evaluate the ability of the turbulent flame speed closure model developed by Zimont for predicting the characteristics of premixed turbulent combustion process in an SI engine. Combustion of the Ricardo E6 single cylinder test engine was modeled with the above turbulent flame speed closure model combined with the progress variable approach, implemented to a commercial computational fluid dynamics code. Full cycle simulations, covering all four strokes including the valve motion, spark discharge, flame kernel development and fully developed combustion, were performed for two different operating conditions of the engine. The engine as fueled with gasoline. Obtained results were compared with experimental data obtained for the same operating conditions of the E6 engine in order to assess the prediction ability of the model. Accordingly, In-cylinder pressure variation and the combustion heat release rate with respect to crank angle were compared with measured values. In general, predictions, of the model was found to be in reasonable agreement with experiment values, but significant discrepancies could be observed in certain operating conditions. In fact, combination of multiple models for different phases of the combustion process was found to require significant fine tuning of model constants to obtain reasonable predictions.