SPRAY STRUCTURES OF AERATED LIQUID FUEL JETS IN SUPERSONIC CROSSFLOWS

The spray structures and the spray penetration heights of aerated liquid jets in a supersonic crossflow were studied experimentally and theoretically. Experiments were carried out inside a 25-mm square supersonic wind tunnel with performance Mach number of 1.85. An effervescent injector was flush mounted on the bottom plate of the supersonic wind tunnel to provide normal injection into the supersonic crossflow. Several plain orifice nozzles with orifice diameters of 380 to 890 pm were tested. Test liquids included water, ethyl alcohol, and a 33% alcohol/water solution. Laser sheet illumination photography and shadowgraph were used for spray visualization and penetration height measurement. Theoretical modeling was based on the assumptions of co-annular spray structure and equal liquid and barbotaged gas velocities at the nozzle exit plane. It was found that the spray transits from the dual mode spray to the pure barbotage mode spray as the amount of barbotaged gas increases. The spray penetration height in the barbotage mode increases with the amount of barbotage gas, due to the increased jet-to-air momentum flux ratios. The theoretical prediction is in good agreement with the experimental data.