The rocket rotating detonation engine (RDE) is a promising technology for its potential large improvement over state-of-the-art alternatives. NASA has identified the RDE as a technology of interest for its in-space propulsion applications such as orbital transfer or planetary lander engines. However, a technology feasibility assessment is not currently possible since the dynamics of the key fluid-combustion-system processes are not well understood for relevant conditions. To achieve a reliable and efficient RDE, various processes must be understood and/or optimized including the fuel-oxidizer propellant mixing, injection of fresh propellants with minimal pressure losses, and the interaction of fresh propellants with combustion products while avoiding deflagration losses. For liquid RDE combustion, measurements simply do not exist that provide detailed characterization of liquid breakup, atomization, vaporization, and burning during the interaction of liquid propellants with shocks and detonation waves. The proposed research focuses on transitioning state-of-the-art, time-resolved measurement techniques to liquid-fueled RDEs to provide information critical for understanding these systems and their design. The proposed research will provide ultra-high-speed (100 kHz–5 MHz) in-situ spatially and temporally resolved imaging of the gaseous oxidizer-liquid fuel mixing, species concentrations, and combustion to anchor and improve numerical modeling predictive capability. The proposed imaging measurements will characterize and measure the gaseous oxygen-liquid fuel mixing, combustion processes, flowfield structure, and dynamics in the liquid-fueled RDEs. Concurrent simulations will be performed at two fidelity levels (a lower fidelity Unsteady Reynolds Averaged Navier Stokes model and a higher fidelity shock-physics/multiphase-combustion mode), enabling improved interpretation of the measurement data and RDE physics, and anchored modeling and simulations.
The proposed R&D work seeks to modernize the measurement technology in RDEs for rocket applications. This includes time and space resolved measurements inside the RDE leveraging new technological developments such as the burst-mode laser. Detailed measurements of the mixing, O/F ratio, quantified deflagration versus detonation, and other key RDE phenomena will be directly compared to numerical simulations to provide boundary conditions and anchor current and future RDE modeling efforts.
Non-NASA applications of the proposed efforts include high-fidelity, spatiotemporal analysis of highly dynamic phenomena and validated modeling. Commercial applications include air-breathing propulsion, stationary power generation, and fundamental research in a wide range of aerothermal flows.