Analysis of Variations in Fuel Spray, Combustion, and Soot Production in an Optical Diesel Engine Operating Under High Simulated Exhaust Gas Recirculation Operating Conditions

In-cylinder visualization experiments were completed using an International VT275-based optical DI Diesel engine operating under high simulated exhaust gas recirculation combustion conditions. Experiments were run at four load conditions to examine variations in fuel spray, combustion, and soot production. Mass fraction burned analyses of pressure data were used to investigate the combustion processes of the various operating conditions. An infrared camera was used to visualize fuel spray events and exothermic combustion gases. A visible, high-speed camera was used to image natural luminosity produced by soot. The recorded images were post-processed to analyze the fuel spray, the projected exothermic areas produced by combustion, as well as soot production of different load conditions. Probability maps of combustion and fuel spray occurrence in the cylinder are presented for insight into the combustion processes of the different conditions. From the analysis presented in this paper, it is observed that, as load is increased, different combustion patterns occur, leading to differences in the patterns of combustion and where soot is produced.