Secondary atomization of thixotropic kerosene gel: Detailed numerical investigation of dynamics and characteristics

Gel propellants, as innovative energy materials, have shown great potential in aerospace applications due to their excellent safety and storage stability. However, their complex rheological properties pose challenges to atomization and combustion efficiency, particularly in understanding the dynamics of secondary atomization, which remains insufficiently explored. This study investigates the secondary atomization of thixotropic kerosene gel droplets (5% organic gel) through numerical simulations and theoretical modeling. A two-phase flow framework incorporating the volume of fluid and adaptive mesh refinement is developed to analyze deformation and breakup dynamics under bag, multimode, and shear breakup modes. The results show that at low Weber numbers (We), bag and multimode breakup exhibit similar initial stages, characterized by windward flattening, leeward stability, and inertia-driven bag formation. The increase in We enhances stamen structure development in multimode breakup, occasionally causing dual-bag formation. Shear breakup initiates with rapid edge ligament detachment, followed by core transition. Droplet size distributions demonstrate complex patterns influenced by breakup mechanisms, with thixotropic gels showing non-monotonic dependence on We and Ohnesorge numbers. Drag coefficients, affected by frontal area dynamics, indicate momentum exchange with surrounding gas. These findings advance understanding of non-Newtonian fluid atomization, providing insights for gel propellant applications in aerospace engineering.