Atomization characteristics of slurry fuels using a pressure swirl atomizer

Slurry fuel, which has a high energy density, is a mixture of liquid or gel and metal fuels (Al, B, Mg) in powder form. Such slurry fuels have non-Newtonian fluid characteristics in the form of shear thinning based on cohesion, inertia, and friction among the metal particles present in the fuel. Additionally, the atomization characteristics of slurry fuels differ from those of conventional fuels and vary according to the metal particle content, mean particle diameter, and injection parameters. In this study, the effects of aluminum particles on slurry fuels were experimentally investigated. To determine the effects of the content and mean diameter of aluminum particles in a slurry on ligament and droplet formation and breakup, microscopic shadowgraph images were captured, and the Sauter mean diameter (SMD) of the droplets was measured. In particular, the breakup mechanisms of liquid films and ligaments, and the impact of an increase in mean particle diameter are discussed. Additionally, for the first time, the effects of shear and elongation rheological characteristics on the atomization performance of a slurry swirl spray are described. When the mean diameter of the aluminum particles contained in the slurry increases from 10 to 21 μm, the breakup length and number of ligaments that cannot be broken up into droplets increase. On the contrary, when the particle size is the largest (54 μm), the breakup length is the shortest and the number of ligaments is the smallest as a result of the effects of elongation rheological characteristics. However, the SMD increases monotonically according to particle content and particle size increases under the effects of shear rheological characteristics.