Composite liquids under high-power heating: superheat of water in micro-explosion of water-in-fuel droplets

The article analyses the degree of water superheating with respect to the liquid-vapour equilibrium line in experiments on the micro-explosion of a composite droplet comprised of two immiscible liquids. The analyses were carried out for water-in-fuel drops under conditions of high-power heating. This degree is compared with the mechanical effect of droplet decay, involving the formation of daughter droplets. Our attention was drawn to the smallness of the degree of superheating preceding the decay. A model of the boiling up of such a droplet is constructed taking into account the sources of premature boiling up of water inherent in micro-explosive experiments. The dependencies of the boiling up temperature of water on the heating rate obtained in the model turned out to be in accordance with the experimental data across a wide range of heating rates. A hypothesis about the local superheating of the transition layer, which is not detected in the experiment, is formulated. Thus, a step has been taken to clarify the essence of the mismatch of the degree of superheating of water recorded by macroscopic equipment along with a completely satisfactory generation of daughter droplets serving as the basis for advanced fuel technology.