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Completed TRL 3 (started at 2, targeting 3)
This proposal describes an experiment designed to measure the wave attenuation characteristics of two-phase flows for application to rotating detonation engines (RDEs). The experiment described within was conceived to help address an important issue with current generation RDEs; it is possible for high pressure fuel-laden exhaust gasses within the combustor to back flow into the injector system and reach the oxygen manifold. This event could result in unintended combustion within the manifold system. A solution to prevent this back flow event is therefore required.
Since gas/liquid propellant combinations are used in numerous rocket combustors, understanding the attenuation characteristics of two-phase mixtures is of immediate interest to the community. Because the attenuation characteristics of two-phase mixtures are poorly understood, these physics are the prime motivation for the proposed research. The proposed experiment will help elucidate these attenuation characteristics by studying how the pressure of the detonation wave decreases as a function of distance.
A cylindrical test chamber, open to the atmosphere at the bottom, will be filled from the top with a water mist generated with a commercial atomizer so that the droplet field is well characterized. A predetonator with mix and ignite a fuel air mixture and direct the resulting detonation wave into the chamber. Pressure transducers along the height of the cylinder will measure static pressure of the air/water mixture within the cylinder as the detonation waves travel in from the bottom. Trials would be run to study the effect of varying gas/liquid void fractions, drop sizes, and detonation strengths on wave attenuation.
The data from these experiments can help minimize injector pressure drops to mitigate catastrophic back flow events. Specifically, data from the proposed experiment would be leveraged to inform part geometry and desired flow conditions that effectively attenuate blow back events, thereby isolating the injectors from the exhaust gasses.
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