In present study, the effect of condensation of ambient gas (steam) on the breakup mechanism were studied through experiments.
In case of condensation of ambient gas, the perforation (formation of holes) breakup mode occurred dominantly. However for laminar sheets ejecting from fan spray nozzles, disintegration is mainly due to the aerodynamic wave breakup mode regardless of condensation of ambient gas. The effect of turbulence in the orifice is shown to be responsible for two types of disturbance in the sheet, either a series of more or less regular circumferential waves (ripples) with the orifice as a center, or a number of local point disturbances (craters), and the latter is the origin of the holes in the sheet. These imply that the formation of local point disturbance depends on the internal shape (or type) of nozzle as well as the flow characteristics of liquid sheet with condensation of ambient gas.
Generally the breakup length of liquid sheet decreases in case of condensation of ambient gas due to the perforation near the nozzle orifice. Also, in case of condensation of ambient gas and low sheet velocity, the breakup length decreases as sheet temperature decreases (subcooling temperature increases). However the effect of subcooling temperature on the breakup length decreases at the high sheet velocity.
