Visualizations of sheet breakup of non-Newtonian gels loaded with nanoparticles

Abstract

Impinging jet atomization of gelled propellants loaded with nanoparticles of energetic metals is important for rocket propulsion as gels combine advantages of conventional solid and liquid propellants. We visualized and quantitatively characterized the sheet atomization of a gelled hydrocarbon rocket propellant mixed with simulant nanoparticles. Two new regimes, open rim with holes and impact wave with longitudinal ligaments, were discovered and characterized quantitatively. Holes and their dynamics are crucial in these regimes. Holes form by tear or puncture of the sheet surface, both of which are possible due to particle clusters, and lead to recurrent web structures. These structures disintegrate into longitudinally oriented ligaments. Non-Newtonian effects are manifested as delay in ligament breakup and change in breakup mode. Viscoelastic effects were observed in the form of ligament retraction in the low pressure drop conditions. Gradual breakup and inhomogeneous distribution of particles on the sheet could lead to hotspots during combustion of gelled propellants atomized by the impinging jets method.