Modeling the vaporization of gel fuel droplets

Abstract

Experimental evidence of the combustion process of gel droplet burning indicates that, at a certain time after ignition, evaporation of the liquid fuel results in the formation of an elastic film of high viscosity gellant around the droplet that prevents further vaporization. As a result, constantly expanding vapor bubbles are produced within the droplet. Eventually, the film is ruptured and a jet of fuel vapor is released. A theoretical, time-dependent model of organic-gellant-based gel droplet combustion has been developed and numerically solved. The results indicate that the evaporation rate of the liquid fuel from the droplet surface and the viscosity of the components comprising the gel droplet affect the formation and modification of the gellant layer. The tensile stress, applied on the gellant film during the formation of the bubbles, reaches high levels in short periods of time and causes the droplet to rupture when it exceeds the layer material yield-point.