Predetonation properties of rotating supersonic combustion engine at varying equivalence ratio

Abstract

Rotating detonation engine (RDE) is a new type of energy conversion system that utilizes detonation and has huge potential in replacing conventional combustion engines. However, to apply the RDE in real application, much work is still required especially in detonation initiation in both the predetonator and annulus chamber of RDE. A proper detonation reactant is crucial in an ignitor such as predetonator. Parameters affecting the formation of deflagration to detonation transition (DDT) in predetonator and predetonation behaviour on rotating wave initiation in RDE also remain unclear. Hence, this study aims to establish baseline fuel composition for predetonator by chemical equilibrium analysis. Calculations for ideal detonation characteristics in term of velocity, pressure, and temperature at varying equivalence ratio are performed using NASA-CEA software. The second aim of this study is to analyze the effects of equivalence ratio, the length of Shchelkin spiral, and the ignition energy in predetonator on DDT. Predetonation characterization that includes the measurement of velocity and pressure in predetonator were done to determine the effect of equivalence ratio, the length of Shchelkin spiral, and the ignition energy on DDT in the predetonator. The third aim for this study is to analyze the effects of predetonation exiting wave velocity to rotating detonation wave (RDW) initiation in RDE. In determining the effect of predetonation exiting wave velocity, characterization of RDW includes the measurement of period between predetonation and detonation and period of rotating detonation stabilization. Acetylene-oxygen (C2H2-O2) results with the highest pressure ratio and temperature ratio thus is chosen as the reactant in the predetonator. Among the studied parameters, the impact of ignition energy is significant in the predetonator application. An average of 7.3% and 322% detonation velocity and pressure increments were obtained when ignition energy was increased from 50 mJ to 100 mJ. By increasing the predetonator exiting wave intensity, the reduction of the stabilisation period is achieved. The findings will guide further research into parameters that could create stable CRDW throughout the operation of RDE.