Evaporation phenomena in superheated atomization and its impact on the generated spray

Applying the process of superheated atomization (flash atomization) finely dispersed sprays with moderate droplet velocities can be obtained, without the necessity of high pressure or an additional gas phase. In this paper occurring evaporation phenomena inside a nozzle capillary and their impact on the generated spray are analyzed. Evaporation is enhanced for increasing superheating. An intensified evaporation induces a considerably extended spray and smaller droplet sizes are generated. Furthermore a reduced mass flux and decreased velocity of the droplets are to be expected. By increasing the amount of vapor spray pulsation, triggered by bubble bursting, is increased. This is shown in acoustic measurements, which also demonstrate a simple way to monitor, or even control the atomization of superheated liquids.