As a means of overcoming the difficulties of achieving a satisfactory fuel atomization over the entire range of engine operation, both airblast forces and high pressure fuel injection are used in one hybrid atomizer design. The objectives of the present effort are to further improve the understanding of the important process of spray interaction in the hybrid atomizer flowfield, and to develop a relatively simple calculation approach that can relate the net effect of the interaction to the atomizer operating conditions. The ratio of the calculated average SMD for both the pilot and main prefilming device of the hybrid atomizer, each operating separately, to the SMD measured for the overall spray, obtained when both fuel devices were operating simultaneously, was used as an indication of the interaction between the two sprays. The experimental investigation demonstrated that stronger interaction between the pilot pressure nozzle spray and the prefilming main spray of the hybrid airblast atomizer occurred at higher pilot fuel pressure, larger pilot spray angle, or lower air pressure drop. It was also noticed that there was an optimum value of main fuel pressure, beyond which a decline in spray interaction was observed. The results indicated that by carefully selecting the pilot spray angle and flow capacities of the atomization devices, satisfactory atomization could be achieved even at lower air pressure drop. The interaction between the pilot and main sprays of the hybrid atomizer in configurations that utilized air swirlers surrounding the atomizer, was strongly dependent on swirler geometry. The extent of the interaction was attributed to changes in the air flowfield around and between the two sprays and the main filming process, all significantly affected the degree of utilization of the airblast effects.

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