In order to satisfy the growing demand for the reduction of fuel consumption and pollutant emissions, various technologies have been employed in diesel engines. Consequently, to determine the optimal combustion control strategy, many parameters such as injection pressure, nozzle diameter, injection timing, injection quantity, and exhaust gas recirculation (EGR) rate should be selected properly corresponding to the engine operating conditions. It is difficult to obtain the appropriate strategies without understanding the change in combustion process when varying these parameters. To realize parametric studies on combustion control strategy of modern diesel engines, a phenomenological combustion model based on stochastic method was developed. In this model, the modeling of the spray tip and tail penetration after the end of injection, and interaction between the sprays of sequent injection stages were focused on to modify the stochastic combustion model for combustion simulation with multiple injection. The effects of swirl, wall impingement, and adjacent spray interaction are formulated simply to make the combustion model more accurate and computationally efficient. The simulation results were compared with experimental data from a single-cylinder test engine for pilot/main two-stage injection. The results reveal that the model has capability to accurately predict the combustion characteristics and emissions of diesel engine with pilot/main two-stage injection.
Part of the book: Developments in Combustion Technology