High Area Ratio Convergent Nozzle to Improve Performance of Rotating Detonation Engine

Building upon previous research with rapid to gradual (RTG) nozzles of area ratio (AR) up to 4.0, this work examines an RTG nozzle with AR = 6.0 and how it affects wave stability, flow uniformity, and pressure gain in a rotating detonation engine (RDE). The experimental setup utilizes an RDE with methane and oxygen-enriched air (67% O₂ and 33% N₂ by volume) supplied to the combustor in a counterflow arrangement. Tests are conducted at equivalence ratios of 0.6, 0.8, and 1.0 and two different mass flow rates (0.18 and 0.32 kg/s), to enable direct comparisons with the previous study. Internal RDE performance is characterized by using pressure measurements across different axial locations, and high-speed imaging at 100 kHz to visualize the wave behavior in the annulus.