Experiments on atomization characteristics of the flash swirl spray

An experimental study on the secondary spray formation and interaction with primary one for the flash swirl spray was performed. To elucidate the vaporization and atomization characteristics on these spray regions, the local temperatures and droplet sizes were measured and averaged on the axial cross-section using a K-type thermocouple and laser-based optical technique, respectively. In order to obtain the physically meaningful mean droplet size, the time-averaging method was also considered as "total SMD." Experiments were conducted by ejecting the superheated liquids (water) into an atmospheric pressure environment with variations of essential injection parameters. The elevation of the superheat degree or the injection pressure activates the thermal atomization in the primary spray owing to the increased available energy, which augments the number percent of drops in the secondary spray by the entrained gas effect. On the contrary, the enlargement of the nozzle diameter, in spite of the unchanged available energy, enhances the atomization characteristics of the primary spray by growing the instability of the liquid sheet due to the increment of the vapor production.