Simulation of liquid droplets combustion in a rotating detonation engine

Abstract

Recent research towards using liquid fuel in rotating detonation engines (RDE) has been assessed here using numerical simulations of a representative three-dimensional (3D) configuration. Eulerian-Lagrangian simulations of a 3D non-premixed RDE configuration are conducted and it is demonstrated that kerosene injection through the air plenum helps stabilize the RDE operation at the conditions where a pure gaseous H2 RDE is unable to sustain the propagation of a detonation. The H2-fueled RDE is first simulated at a global equivalence ratio of 0.5, which shows unstable burning with localized extinction and re-ignition followed by system failure, and then compared against another simulation where kerosene droplets are injected in the air plenum keeping the same H2 fueling condition. The results show that the existence of the detonation aids in the evaporation of the injected droplets behind it, allowing the vaporized mixture to properly mix before the next detonation cycle such that continuous (cyclic and stable) propagation can be achieved. It is further shown that whereas hydrogen mainly reacts near the bottom of the chamber, the injected droplets vaporize slow and react at larger heights. As a result, for the latter case the heat release is more distributed and provides an additional mechanism to stabilize the detonation cycle.