Development of a Non-Equilibrium Plasma Assisted Rotating Detonation Engine

Abstract

A rotating detonation engine (RDE) is an experimental engine which uses constant volume detonative combustion in order to produce thrust. This type of combustion process is up to 20% more efficient than standard deflagration engines which use con- stant pressure combustion [24]. An RDE uses rotating detonation waves which travel along the wall of the chamber to produce a constant thrust as opposed to a pulse det- onation engine (PDE), in which discrete pulsed detonations must be initiated at high frequencies. RDEs thus maintain higher thrust densities and suffer from fewer deto- nation initiation issues than PDEs [27]. However, typical RDE designs incorporating an annular combustion chamber experience immense heat flux to the walls of the annulus, requiring complicated designs and cooling systems to prevent overheating. New research suggesting the viability of cylindrical-chambered RDEs has opened new possibilities for more simplistic RDE designs [52]. Kasahara developed a 2-cm RDE and observed detonation at flow rates over 22.5 grams/second; however, there were issues with detonation stability [59]. Additional research has demonstrated the capa- bility of using plasma to assist in detonation stabilization and initiation through the generation of free radicals that facilitate combustion. To combine these two research topics, and using Kasahara’s engine as a model, this project saw the complete design, manufacturing, assembly, and testing of a functional Ethylene/Oxygen engine which could utilize plasma to promote detonation stability and initiation. Plasma was suc- cessfully generated at various environmental conditions, and deflagration combustion was achieved at propellant inlet pressures of 20 psig and 65 psig and flow rates of 0.3 and 1.09 g/s. Experimental values of the mass flow rates were measured to be vastly below the predicted values, suggesting that the effects of viscous forces, friction, and turbulence in the injection microchannels were significant. Due to several safety and time constraints, the design was unable to be fully tested, and as a result the effect of plasma on the combustion process was not explored. In the future, trials at higher mass flow rates and trials with the plasma generator operating will be conducted.