Evaluating the Effects of Fill Height in a Narrow Detonation Channel

This study evaluated the effect of changes in reactant fill heights on detonation behavior through hydrogen and air mixtures in channels. This was accomplished by attaching a straight detonation channel with optical access to a rotating detonation combustor (RDC). The RDC was operated independent of the channel, thus allowing for control of the reactant fill height in the channel. Wave speeds, wave angles, reactant fill heights, wave heights, and peak radiation intensities were quantified. This study showed that minimum operability limits for detonations in channels in terms of fill height ([Formula: see text]) normalized by mixture cell size ([Formula: see text]) were near [Formula: see text]. Evidence of reactants not burning in detonation mode were identified at the lower equivalence ratios (i.e., 0.7–0.8). Higher fill heights correlate with larger amounts of reactants failing to detonate or deflagrate after a detonation wave passed, indicating lower efficiencies. Fill height models for RDCs were compared to experimental results obtained from the detonation channel, with some agreement at stoichiometric conditions but poor agreement at fuel lean conditions. Results of this study provide useful insights into the effects that fill height in an RDC can have on operability limits, combustion inefficiencies, and wave structure that exists inside the combustor.