Studies on Fuel Spray Combustion by Visualization of a Diesel Engine with a Side-Injection System

In the side-injection system where several injectors are arranged on the circumference of the combustion chamber, the interaction between spray jets and air swirl is more complicated than the conventional central-injection system. The authors have examined in the past the influences of air swirl on the combustion performances in this system by a test engine. In the present studies, the authors have rebuilt the engine to take high-speed photos from the lower part of the combustion chamber. Comparing the visualized data with the results of operation tests, it has become clear that the lowest exhaust smoke density and BSFC can be achieved when the fuel sprays curbed and dispersed by air swirl fully occupy the combustion chamber. Moreover, the effects of air swirl on the dispersion and combustion of fuel spray have been examined in detail with the observation of a single spray jet.