Stability investigation of two-phase n-decane rotating detonation waves

Abstract

In this paper, three-dimensional rotating detonation combustor fuelled by n-decane sprays is numerically investigated with Eulerian-Lagrangian method. The flow field characteristics, the effects of injection total pressure and oxygen mass fraction on the stability of two-phase rotating detonation wave are analysed. The results show that the mixing-dominance and the reaction-dominance are two mechanisms affecting the stability of two-phase rotating detonation wave. Specifically, injection total pressure mainly affects the fuel mixing in non-premixed configuration. Increasing the total pressure improves the droplet evaporation, such as the reduce of the droplet evaporation distance, Sauter mean diameter and the rise of droplet evaporation rate. Besides, the stability of two-phase rotating detonation wave is nonlinear, the highest stability happens in 1.5MPa, which is due to the collision of shock wave and rotating detonation wave. On the other hand, oxygen mass fraction has a significant effect on the reactivity of reactant and leads to the wave propagation mode transition. The increasing of oxygen mass fraction broadens the high reaction rate zone, which provides a suitable environment for the generation of local explosions. The local explosions gradually develop into detonation waves and form multi-wave mode after a complex self-adjusted process. Moreover, the stability of two-phase rotating detonation wave is in proportion to the oxygen mass fraction. As the increase of oxygen mass fraction, the fluctuations of pressure and detonation speed tend to be smooth, which implied the higher stability in multi-wave mode. The analysis about stability of RDW may be beneficial to the design of two-phase rotating detonation engines.