Event Tag: Aeronautics

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Detonation-Based Combustion for High-Speed Propulsion Systems

Detonation-based engines have recently gained substantial interest as an alternative to traditional deflagration-based propulsion systems, with the theoretical potential to achieve overall engine performance gains in a more compact volume. Specifically, rotating detonation rocket engines (RDRE’s) can exhibit an increase in chamber pressure, temperature and exhaust gas velocity for a substantially lower injection pressure through a near constant-volume combustion process, compared to constant-pressure devices. If these benefits are successfully realized, this can result in overall engine performance gains (i.e., increased thrust and specific impulse) up to ~10% or a 5X reduction in required injection feed pressures.

During RDRE operation, one or more detonation wave(s) travel around the annulus supersonically by continuously consuming the incoming reactants while producing combustion products that exit the open end of the engine. Experimental work performed at the University of Alabama in Huntsville (UAH) in collaboration with the Air Force Research Laboratory (AFRL) is focused on characterizing engine behavior of a small-scale RDRE for versatile in-space propulsion

Specifically, this work aims to measure engine performance (i.e., thrust and specific impulse), determine the operability range for various flow conditions, and characterize the corresponding operating detonation modes for a 100 N, 25 mm outer diameter detonation-based thruster. Current emphasis is placed on investigating various chamber geometries including both annular and cylindrical configurations, as well as different fuels (i.e., methane, hydrogen); this aims to demonstrate engine behavior sensitives towards the development of engine scaling approaches for determination of the minimum engine size supporting robust detonation. Additionally, to greater understand how to create and sustain high-strength detonations in compact RDREs, fundamental studies into characteristic timescales and coupling mechanisms for detonation-based engine processes including chemical kinetics, injection, flow and acoustic are required. Using various first principle analyses, these timescales are quantified for a variety of fuels, along with different non-idealities being present (e.g., pre-burning). In total, results from these studies advance the understanding of RDREs for future designs that may lead to performance gains above those achievable from traditional designs.