Liquid Fuel Survey for Rotating Detonation Rocket Engines

Abstract

The majority of current research into rotating detonation rocket engines (RDREs) has focused on the detonation of gaseous propellants. Liquid-liquid RDREs -- where both propellants are introduced to the chamber in their liquid phase -- are of interest because of their predicted higher performance potential due to the much higher detonation pressures and temperatures evolved from the detonation of the high-density, liquid mixtures. Few studies in the open literature have explored fully liquid propellant combinations and fewer have been propellants directly applicable to booster-applications. It is unknown if fuels that are trademarks of the constant pressure engine (CPE) field, like hydrogen, kerosene (RP), and methane, are the optimal option for an RDRE. In an RDRE, the peak detonation pressure and temperature and deflagration time scale of a propellant combination contribute to both the viability and performance of the engine; these properties do not necessarily correlate with desirable features for CPE propellants. In the following study, the detonation of liquid oxygen with fourteen different liquid fuels is considered with respect to properties relevant to RDREs. Three fuels -- methane, RP, and propylene -- were chosen for further evaluation with a 0-D liquid-liquid RDRE performance prediction code. This survey provides a baseline for comparison of liquid fuels; however, experimental studies will be required to baseline the performance prediction method and ascertain the importance of the propellant properties critical to RDRE operation and performance.