Performance of a Radial Rotating Detonation Engine with an Aerospike

A second-generation radial rotating detonation engine (RRDE) made of copper has been installed and operated to build upon the experience gained with the first-generation aluminum RRDE. The RRDE is integrated with an aerospike to expand the flow in the axial direction and incorporates parallel discs with a constant height between them to yield a linear decrease in cross-sectional area in the flow direction. Performance of this new copper engine is analyzed using a) capillary tube attenuated pressure (CTAP) ports in the combustor channel, at the geometric exhaust throat, and on the aerospike surface, b) high-speed fluctuating wall static pressure measurements by PCB piezo-electric probes, and c) thrust data acquired by a six-axes load cell. Experiments were performed with methane fuel and oxygen-enriched air mixtures at varying reactant flow rates and equivalence ratios. Steady RRDE operation was achieved, and complex wave modes and shifts were observed which correlated with the pressure traces inside the engine and over the aerospike and affected different parameters of performance. "Initial" reactant pressure and equivalent available pressure at the throat are measured and postulated to estimate the pressure gain in the combustion section in isolation from the injection losses.