Experimental Study of Reactant Mixing in Model Rotating Detonation Combustor Geometries

Reactant mixing has been identified as one of the driving factors for successful and stable operation of Rotating Detonation Combustors (RDC). This work investigates the stationary mixing in a scaled model RDC cross section in a water tunnel. Two configurations with one and five dyed water jets injecting into a confined water crossflow modeled the mixing scheme used in the radially inward injecting RDC at TU Berlin. The influence of several parameters on the mechanisms driving the mixing quality was investigated, with the objective of improving future injection strategies. The parameters studied were: the position of the fuel injectors relative to the RDC outer wall, the shape of the corner between the oxidizer injection slot and the detonation annulus, and the ratio of fuel to oxidizer momentum flux. High-speed PLIF imaging of the longitudinal plane centered at the middle jet injection hole, as well as of several planes perpendicular to the longitudinal plane, confirmed the existence of a strong shear layer and recirculation zone at the RDC outer wall corner that significantly influenced the mixing. Depending on the jet location and the jet-to-crossflow velocity ratio, different mechanisms impacted the reactant mixing.