Numerical Study of Spray Combustion Effects on Detonation Propagation

Considering the recent interest in the use of liquid fuel in rotating detonation engines, there is a need to understand the interactions of a detonation wave with liquid fuel. Detonation propagation in a three-dimensional periodic channel is simulated in this work using Eulerian-Lagrangian reactive simulations. To model the nonhomogeneity of combustion, discrete injectors for gaseous hydrogen fuel are used; and the liquid spray is injected along with the air from a continuous plenum. The results show that when the hydrogen injection rate is reduced to a certain condition, the detonation wave is unable to sustain; but the injection of the kerosene spray helps it sustain, and the system transitions from a pure gaseous detonation to a hydrogen-driven kerosene-sustained detonation. The effect of the droplet injection diameter and the fuel mass-flow rate are also studied. Hydrogen promotes the vaporization and the burning of kerosene droplets. Kerosene vaporization is a relatively slow process, and the vapor burns as either a weak detonation or through the postshock region, which in turn provides sufficient energy for detonation propagation. Therefore, the contributions of both fuels are interlinked and responsible for sustaining the continuous propagation of the detonation wave.