Thermodynamic Modeling of Jet Formation and Combustion in Common Rail Multi-Jet Diesel Engines

A two zones combustion model suitable for the engine control design of common rail multi-jet Diesel engines is presented. The modeling approach is based on a semi-empirical two-zone combustion model coupled with identification analysis in order to implement a predictive tool for simulating the effects of control injection strategies on combustion and exhaust emissions. Fuel jet formation and combustion for both premixed and diffusive regimes are predicted, by dividing the combustion chamber into two control volumes; these account for the fuel jet and the surrounding air, composed by fresh air and residual gases; the fuel jet is divided into two zones to separate liquid and vapor phases.

The simulation results have shown that the model predicts the effects of different injection parameters in case of single and multiple injection in a short computational time, suitable for the accomplishment of intensive simulations or optimization analyses over generic engine driving cycles. Moreover model accuracy has been successfully tested over a wide set of experimental data, composed of nearly 100 engine cycles measured on a commercial common rail multi-jet Diesel engine.