Fuel injection spray and combustion chamber wall impingement in large-bore industrial diesel engines

Although the Diesel Engine has existed for over 100 years and it has undergone numerous improvements to the original design it is still noted to have high specific output of harmful emissions. One possible solution for reduction of the harmful emissions from the Diesel engine is greater control over the fuel injection event during the Diesel cycle.; To gain a further understanding of the liquid phase Diesel fuel injection spray characteristics a 2.44 liter displacement, 4 stroke cycle, Caterpillar Single Cylinder Oil Test Engine was modified for optical access and then fitted with a Caterpillar Hydraulic Electronic Unit Injection system. The data collection system consisted of a high repetition rate diode pumped Nd:YAG laser frequency doubled to emit at 532 nm used for illumination and a Kodak Ekta-Pro High Speed Motion Analyzer for recording the spray images.; The engine was motored under various inlet conditions intended to create engine combustion chamber conditions typical of those found in commercially installed Diesel engines of a similar per cylinder displacement class. Parameters studied as independent variables that could affect fuel injection characteristics were; combustion chamber density at top dead center, combustion chamber temperature at top dead center, engine speed measured in revolutions per minute, fuel injection pressure and fuel injection duration. Liquid fuel spray characteristics measured were; maximum linear penetration distance, maximum spray spreading angle and average penetration velocity out to the maximum penetration distance.; Results showed that similar to fixed volume chamber studies increase in combustion chamber density or temperature at top dead center and increase in engine RPM would cause a decrease in spray penetration distance, spreading angle and velocity. While an increase in fuel injection pressure would cause a decrease in spray penetration while increasing spreading angle and penetration velocity. Changes in fuel injection event duration did not show a clearly discernable trend.