Development of a Simulated Altitude Test Facility for Hypergolic Rotating Detonation Rocket Engines

Rotating detonation rocket engines (RDREs) are a quickly-growing area of research in the field of chemical rocket propulsion. The promise of increased thermodynamic efficiency from the pressure-gain combustion cycle has promoted research and development of RDRE technology for an ever-expanding range of systems. Recently, there has been interest in developing RDRE technology for in-space propulsion systems. At the Purdue Altitude Chamber facility, some of the first testing of an RDRE operating with state-of-the-art in-space propellants monomethyl hydrazine (MMH) and mixed oxides of nitrogen (MON) has been performed at simulated altitudes using an experimental 100-lbf-scale thruster from GHKN Engineering, LLC. This work presents the development, modeling, and operation of the test facility at the Maurice J. Zucrow Laboratories for the simulated-altitude testing of an RDRE using hypergolic propellants. The first chapter presents a brief history of the Purdue Altitude Chamber Facility and background information about rotating detonation rocket engines and of supersonic exhaust diffusers, which are commonly-used devices in simulated-altitude testing of rocket engines. The second chapter presents an overview of the test facility and its design, including the vacuum system, the propellant feed system, and the cold flow test stand used to support the test program. The propellant feed system is analyzed in detail to assess the accuracy of theory in predicting the behavior of the feed system in propellant delivery and measurement. The third chapter presents a computational study of the supersonic exhaust diffuser and comparison with test data. Computational methods are developed for the prediction of diffuser performance with RDREs and other annular combustion devices. While rotating detonation has not yet been observed in testing, hot-fire results corroborate the predicted behavior of an annular combustor with a second-throat exhaust diffuser. Operating an RDRE at simulated altitude and with hypergolic propellants MMH and MON represents a novel field of research in detonation-based combustion devices. The development of the test facility for this work at Zucrow Labs is a significant step towards further developing RDRE technology for in-space propulsion applications.