An investigation has been carried out on the spray penetration and soot formation processes in a research diesel engine by means of a quasi-dimensional multizone combustion model.
The model integrates a predictive non stationary 1D spray model developed by the Sandia National Laboratory, with a diagnostic multizone thermodynamic model, and is capable of predicting the spray formation, combustion and soot formation processes in the combustion chamber.
The multizone model was used to analyze three operating conditions, i.e., a zero load point (BMEP = 0 bar at 1000 rpm), a medium load point (BMEP = 5 bar at 2000 rpm) and a medium-high load point (BMEP = 10 bar at 2000 rpm). These conditions were experimentally tested in an optical single cylinder engine with the combustion system configuration of a 2.0L Euro4 GM diesel engine for passenger car applications.
The experimental spray tip penetration and spreading angle were evaluated on the basis of images acquired by means of a high-speed CCD camera, while the experimental trend of the in-cylinder soot concentration was derived by means of the two-color pyrometry method.
The acquired experimental data have allowed useful information to be obtained for the assessment of the multizone model. Well-defined trends between some of the model parameters and the engine operating conditions (namely, speed and load) have been found and preliminary correlations have been developed.
