Detonation Wave Propagation in an Unwrapped RDE Channel

The nature of the coupling between shock wave and combustion zone in a partially-open channel geometry is investigated experimentally and analytically. The channel geometry used in this investigation constitutes a canonical configuration, which simulates an unwrapped shape of a rotating detonation engine (RDE) combustor. In this canonical configuration, controlled reactants are injected transversely from the channel base using a set of model injectors, and detonation waves are established from one or both ends of the channel at a controlled timing to simulate RDE operation. The principal objective of the research is to build the scientific knowledge and the quantitative database for better understanding the physical processes that occur in RDE combustors. For such a configuration, it is observed that there are substantial differences as well as similarities in measured detonation wave characteristics when compared to the previously known properties of detonation waves, which are associated with a fully-confined duct geometry. While the similarities include mostly qualitative observations such as extremely complex three-dimensional detonation structure, unstable and oscillating lead shock wave strength, existence of the triple points detonation cells, etc., there are also some notable differences in the wave structure, the characteristic cell size, and the characteristic wave speed associated with various reactant mixtures using the present configuration. These differences are attributed not only to the partial confinement effect but also to the effects of non-uniform mixing and the injector dynamic response associated with the particular boundary conditions.