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

This paper 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 flow rates 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 thermo-chemical variables with the propagating waves in the chamber. We analyzed the behavior of pressure, heat-release rate, other thermo-chemical 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.