Symmetric, Square, Lattice Pattern Injector Design and Experimental Flow Characterization Within a Detonation Engine

Flow inside a rotating detonation engine (RDE), which is studied for use in aircraft and rocket propulsion, is affected by the geometry of the injector component. Typically, RDEs are cylindrical in nature and have a circular injection pattern. However, although hollow RDEs are now being studied, the injector pattern has remained the fixed-radius, circular injector pattern. In order to understand the impact of uniform injection across the entire cross-sectional area of a combustor inlet, the current research sought to conceptualize, design, and test a bi-propellant RDE with a symmetric injector pattern, and elucidate detonation propagation. In this investigation, different injector patterns concepts were studied, and a symmetric, square, lattice pattern injector was designed and fitted to a square combustion chamber. Combustion tests were conducted with mass flowrates between 30-38 g/s, equivalence ratios between 1.0-1.6, and from back pressures of approximately 5 kPa. Experimental data revealed unidirectional detonation wave motion, reflected waves co-existing with the detonation wave under stable operation, non-uniform pressure near the combustor inlet, increased wave velocity compared to a previous hollow engine tested at Nagoya University, potentially improved reactant mixing in the chamber, and a 94° phase shift when decomposing the detonation wave motion into rectangular coordinates.