Effects of oxygen concentration and kerosene droplet variations on two-phase rotating detonation under afterburner inlet conditions

Abstract

The integration of rotating detonation in afterburners, especially with liquid fuels like aviation kerosene, holds significant engineering promise. This paper employs the Eulerian-Lagrangian method to simulate two-phase rotating detonation with kerosene droplet/vapor/oxidizer mixtures under afterburner inlet conditions. The impact of oxygen concentrations on gas-phase detonation and two-phase rotating detonation is determined using a two-dimensional configuration, with particular focus on the droplet equivalence ratio and initial droplet diameter on propagation and heat release characteristics under low oxygen concentration. A linear decrease in detonation wave velocity with decreasing oxygen concentration, with two-phase detonation velocity loss being approximately 5–10% greater than that of gas-phase detonation. The findings show that the critical oxygen concentration required to sustain gas-phase detonation is 12%, whereas for two-phase detonation, it is 0.5–2% higher. Under high pre-evaporation volume (Φ_l = 0.2), wave velocity increases with decreasing droplet size due to the formation of vapor pockets from heated small droplets, which disrupts the homogeneous premixing state and affects wave propagation. Conversely, under low pre-evaporation conditions (Φ_l = 0.5), maintaining detonation wave self-sustainability relies not only on kerosene vapor heat release but also on effective droplet evaporation. Larger droplets hinder heat release, leading to decreased wave velocity as droplet size increases. To analyze the effect of droplet evaporation kinetics on detonation wave propagation, we examined the filling zone stratification and the heat release distribution. The combustion partitioning was carried out by calculating the equivalent heat release rate, and two typical forms of post-wave secondary combustion were pointed out.