Three-dimensional Numerical Simulations of a Liquid RP-2/O[formula omitted] based Rotating Detonation Engine

Abstract

Rotating detonation engines (RDEs) offer increased thermal efficiencies and continuous thrust in a compact design. While non-premixed RDEs, where fuel and oxidizer are injected into the combustor through separate streams, have been extensively studied through experiments and numerical simulations, practical realizations of this technology mandate the use of the liquid fuels that power propulsion devices today. As a result, the strength and stability of the detonation wave are heavily influenced by not only the injection scheme but also the quality of the fuel mixture prepared for detonation. This mixture is a product of the dispersion and evaporation dynamics of liquid droplets in the presence of propagating detonation waves. To this end, the multiphase RDE system is investigated through high-fidelity simulations of a rocket-type RDE (RDRE) with liquid RP-2 fuel and gaseous oxygen. The Eulerian-Lagrangian compressible flow solver developed here provides detailed insight into the physical mechanisms important in a multiphase environment. A series of simulations are employed to understand both the droplet dynamics and mechanisms that lead to stable multiphase detonations and their resulting detonation structure. The interaction of the oxidizer injector, liquid droplets, and the detonation wave is discussed extensively. The injector dynamics lead to variations in droplet motion, where the injector recovery process enforces recirculation zones. Most importantly, the penetration of the injected droplets is crucial in their ability to evaporate; the lack thereof can quench detonation and result in a chaotic, deflagration-like mode. The injection scheme is crucial in the dispersion and evaporation of liquid droplets and the formation of detonable mixtures, perhaps more so than in gas-phase systems. The simulations provide detailed insight into the design of liquid-fueled RDE systems.