A Laboratory Investigation into the Fuel Atomization Process in a Diesel Engine for Different Configurations of the Injector Nozzles and Flow Conditions

This paper reports a laboratory investigation of the fuel injection process in a diesel engine. The atomization process of the considered fuel (a hydrocarbon liquid) and the ensuing mixing with air is studied experimentally under high-pressure conditions. Different types of injector nozzles are examined, including (two) new configurations, which are compared in terms of performances to a standard injector manufactured by the Bosch company. For the two alternate configurations, the intake edges of one atomizing hole (hole No. 1) are located in the sack volume while for the other (hole No. 2) they are located on the locking cone of the needle valve. The injection process, the fuel atomization fineness and fuel supply speed characteristics are studied as functions of high-pressure fuel pump camshaft speed and rotation angle. The results obtained show that a decrease in the high-pressure fuel pump camshaft speed can produce fuel redistribution depending on the injector operation. In general, however, the hole No. 1 can ensure fuel flow with higher speed with respect to the hole No. 2 for all the operation modes of the injector. Based on such an analysis, we conclude that the use of certain injectors can enable a fine tuning of the propagation process of fuel sprays into various areas of the diesel engine combustion chamber.