Spray characteristics of aluminized-gel fuels sprayed using pressure-swirl atomizer

Abstract

A slurry fuel is a non-Newtonian shear-thinning fluid with high viscosity. The fuel has a high energy density and has advantages in feed control. When the slurry fuel is injected using a swirl atomizer, the spray characteristics change because the rheological characteristics are different from those of the conventional liquid fuel. In particular, the metallic fuel contained in the slurry is an important parameter that dominates the rheological properties, breakup mechanism, and performance of the slurry swirl spray. In this study, an experimental analysis was performed to investigate the effect of aluminum particles on the spray characteristics of the slurry fuel. The rheological properties (shear-viscosity traces), mass flow rate, and discharge coefficient of the slurry composition were measured, and the influences of the particle content and mean diameter on the spray characteristics of the slurry fuel were explained. The content and mean diameter of the particles were found to be proportional to the viscosity of the slurry, and the flow behavior changes with respect to the particles. As the viscosity increases because of the particles, the mass flow rate and discharge coefficient increase because of the increase in the liquid-film thickness. The kerosene gel and slurry swirl spray undergo a breakup process via an aerodynamic mechanism, forming web-like ligaments, which do not appear in the kerosene because of increase in viscosity. As the injection pressure is increased, the frequency of the pulsation generated in the liquid film increases, and the web-like ligaments tend to be dense. When the particle content decreases, the same phenomenon occurs. As the particle content increases, the breakup length tends to increase with the increase in the thickness of the liquid film. However, the breakup mechanism changes depending on the thickness of the liquid film when the mean diameter of the particles changes. The spray angle is inversely related to the viscosity change due to the particles.