Validating the Phenomenological Smoke Model at Different Operating Conditions of DI Diesel Engines

摘要

A new phenomenological model that was published in Aghav et al. (2005, "Phenomenology of Smoke From Direct Injection Diesel Engines," Proceedings of ICEF2005, ASME Paper No. 1350) encompasses the spray and the wall interaction by a simple geometrical consideration. The current study extends this earlier work with investigations made on 16 different engines from six-engine families of widely varying features, applied to off-highway as well as on-road duty. A dimensionless factor was introduced to take care of the nozzle hole manufactured by hydroerosion, as well as the conical shape of the nozzle hole (k factor) in the case of valve-closed-orifice type of nozzles. The smoke emitted from the wall spray formed after wall impingement is the major contributor to the total smoke at higher loads. As the fuel spray impinges upon the walls of the combustion chamber, its velocity decreases. This low-velocity jet contributes to the higher rate of the smoke production. Therefore, the combustion bowl geometry along with injection parameters play a significant role in the smoke emissions. The new model is one dimensional and based on the recent phenomenological description of spray combustion in a direct injection diesel engine. The satisfactory comparison of the predicted and observed smoke over the wide range of engine operation demonstrated applicability of the model in simulation study of combustion occurring in direct injection (DI) diesel engines.