Thermal Dynamics of a Small Vaporizing Slurry Droplet in a Hot and Radiant Environment; Feasibility of the Secondary Atomization

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Abstract
A two-dimensional model and an algorithm for numerical studies of vaporization dynamics of small multiphase fuel droplets suspended in the superheated vapor and irradiated from one side by a high-temperature thermal radiation is presented. Theoretical estimates of distributions of radiant heal sources inside the droplets are obtained by an application of light scattering theory and the extended effective medium theory. The plotted three-dimensional absorption patterns show the hot spots within the irradiated fuel droplets. The two-dimensional model of transient heat dissipation, inside the rapidly vaporizing coal-water slurry droplet, with kinetic boundary conditions is simulated by an application of the Monte-Carlo method. The effect or temperature of the incident thermal radiation, as well as the effects of temperature and pressure of the ambient gas on the feasibility of explosive boiling of the fuel droplets arc studied in detail. The results of compulations predict conditions at which the radiation induced secondary atomization of the slurry droplets in combustors at atmospheric pressure might be possible. In combustors of heat engines operating under high pressures the described mechanism of the radiation induced internal boiling is predicted not to lead to the secondary atomization of coal-water slurry droplets.