Numerical Investigation of Wave Dynamics During Mode Transition in a Hydrogen-Fueled Rotating Detonation Engine Combustor

Abstract This article presents a numerical investigation of mode transition and the associated wave dynamics in a three-dimensional rotating detonation engine (RDE) combustor. The computational setup follows a past experimental study of an RDE combustor, which utilizes hydrogen as the fuel and air as the oxidizer. We consider a configuration at the global equivalence ratio, ϕ=1, which exhibits the presence of a single detonation front propagating in a cyclic manner in the annular combustion chamber. After establishing the single-wave mode, we alter the mass flowrates of fuel and oxidizer while ensuring the same value of ϕ. The simulation was able to capture the wave mode transition from a sustained single detonation wave structure to a double co-rotating detonation wave structure in good agreement with experiments. The transition occurs due to inhomogeneities of fuel/air mixing and a nonlinear interaction of thermochemical variables with the propagating waves in the chamber. We analyzed the behavior of pressure, heat-release rate, other thermochemical quantities, and mixing efficiency during the wave mode transition, which shows the effects of fuel/air mixing leading to the presence of deflagration mode of burning apart from the cyclic propagation of the detonation fronts.