Study of Enstrophy Dynamics During the Mode Transition in a Hydrogen Fueled Rotating Detonation Engine Combustor

Abstract In this study, the dynamics of enstrophy and terms contributing to its amplification and attenuation are examined for a rotating detonation engine (RDE) combustor. The analysis is performed using a dataset obtained from unsteady RANS simulations, which showed the transition from a sustained single detonation wave to a double co-rotating detonation wave in good agreement with experiments when mass flow rates of fuel and oxidizer are changed while maintaining the same equivalence ratio. The results show that the presence of detonation waves and inhomogeneities in the reactive flow field leads to the production and dissipation of enstrophy, particularly in the vicinity of the rotating detonation fronts. The mixing efficiency shows an inverse relationship with enstrophy where it increases sharply near the injection region and saturates at downstream locations. The vortex stretching, dilatation, and baroclinic effects contribute positively to enstrophy in the vicinity of the detonation front and exhibit significant spatial variations during the wave mode transition. During the transition phase, the magnitude of all the terms contributing to enstrophy increases compared to instants when sustained single/double detonation fronts are observed.