Disruptive Burning Mechanism of Free Slurry Droplets

Abstract

A stream of free, monodisperse droplets of boron/JP-10 slurries, prepared in the laboratory, was projected downward into a high-temperature, atmospheric-pressure, oxidizing gas stream. High molecular-weight organic dispersing agents were found to be responsible for the violent disruption of the primary slurry droplets burning with an envelope diffusion flame. The time to disruption increased as (1) the concentration of the dispersant was decreased, (2) a dispersant with higher initial pyrolysis temperature was used, and (3) the size of the suspended solid particles in the slurry was increased. The quiescent vapor-phase combustion of unstabilized slurry droplets generated spherical “solid” boron agglomerates, while the disruptive burning of stabilized slurry droplets resulted in quasi-spherical hollow shells along with their fragments. In the light of the combined role of dispersing agents and solid particles in the formation of the agglomerate shells, a physical mechanism of the process leading to disruption is proposed herein. This work clearly demonstrates that the choice of dispersants for slurries not only affects the slurry stabilization but may significantly modify its combustion properties and those of the agglomerates formed.