Impact of evaporation, swirl and fuel quality on the characteristics of sprays typical of large 2-stroke marine diesel engine combustion systems

Abstract

The acquisition of fundamental reference data with regard to the spray and combustion characteristics in large marine diesel engines is an absolute prerequisite for the systematic application of existing computational models. For this purpose, a novel experimental test facility has been realized to reproduce the operational characteristics of marine diesel engines at start of injection with respect to the thermo- and fluid dynamic conditions as well as regarding the physical dimensions. First reference data generated on the spray evolution (penetration, cone angle) by means of shadow-imaging contribute to the generally improved understanding of in-cylinder processes and allow the validation of simulation models. Based on preceding analyses of measurements at evaporating conditions, additional experiments have been performed to study the spray evolution in a non-evaporating environment at different gas densities. Moreover, the effect of the swirl level on the injected fuel spray has been investigated in order to obtain a better understanding of the interaction of the spray and the gas flow. Finally, the influence of fuel quality variations has been assessed by comparing data from first tests, where heavy fuel oil was used instead of light fuel oil.