Transient Heating and Burning of Droplet Containing a Single Metal Particle

Abstract

An analytical and numerical study of combustion of an isolated liquid hydrocarbon and a liquid hydrocarbon droplet containing a metal particle is presented. The objective is to formulate a simplified combustion model, which accounts for the unsteady gas phase. Further, the model is extended to include an idealized configuration of metal slurry droplets in which a metal particle is enveloped by liquid hydrocarbon, so that ignition characteristics of the metal particles can be studied. The governing spherically symmetric, unsteady conservation equations are simplified using the Schvab-Zel'dovich and von Mises transformations. The liquid-solid phase includes the effect of transient heating. Results indicate that the burning rates for a composite droplet are close to those for a corresponding all-liquid droplet. It is found that in absence of forced convection, unless the ambient air is preheated to large temperatures comparable to the aluminum oxide melting point, the flame does not possess sufficient energy to ignite the metal. It is shown that conduction from the flame is the dominant heat transfer mechanism.