An Improved Phenomenological Soot Formation Sub-Model for 3-D Diesel Engine Simulations: Extension to Agglomeration of Particles Into Clusters

An extension to a phenomenological sub-model for soot formation to include soot agglomeration effects is developed. The improved sub-model, consisting of six coupled differential equations, was incorporated into a commercial CFD code and used to investigate soot formation in a heavy-duty diesel engine. The results of the numerical simulation show that the soot oxidation process is reduced close to the combustion chamber walls. This is due to the lower charge temperatures encountered as a result of heat transfer to the combustion chamber walls. The sub-model predicts that larger soot particles and clusters are encountered in the annular region close to the combustion chamber walls at the end of the combustion cycle. These results are consistent with available in-cylinder experimental data on soot.