An extended flamelet model for multiple injections in DI Diesel engines

Combustion modeling using the Representative Interactive Flamelet (RIF) model has proven Successful in predicting Diesel engine combustion. The RIF model was previously used for Diesel engine combustion processes with not more than two consecutive injections into the combustion chamber. In this study, the RIF model is extended allowing for any number of injection events. First, the two-dimensional laminar flamelet equations, which can describe the transfer of heat and mass between two-interacting mixture fields, are introduced. This is followed by a description Of the various mixture fraction and Mixture fraction variance equations that are required for the model extension accounting for Multiple injection events. Finally, the modeling strategy for Multiple injection events is derived: Different phases of combustion and interaction between the mixture fields resulting from different injections are identified. Based on this, the extension of the RIF model to describe any number of injections is Put forward. Simulation results using the extended RIF model are compared against experimental data for a Common-Rail DI Diesel engine that was operated with three injection pulses. For the pilot injection and the main or post injection, respectively, different ignition phenomena are pointed out and the influence of the scalar dissipation rate on these ignition phenomena is investigated in detail. (c) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.