Experimental investigation on spray and detonation initiation characteristics of premixed/non-premixed RDE

Abstract

In rotating detonation engines (RDE) supplied with liquid fuel, stability of the detonation wave considerably depends on the quality of mixing in the gas–liquid flow field. In this study, RDE and linearized RDE, using aviation kerosene (RP-3) and oxygen-enriched air with 29% oxygen content as propellants, are proposed to analyze the characteristics of cold-state spray and detonation initiation. The result is more evident in non-premixed RDE, where the recirculation zone in the combustor affects the movement of droplets and concentration distribution of kerosene. As the combustor pressure increases, speed of the airflow entering the combustor decreases and the aerodynamic shearing effect is weakened, which is not conducive to droplet breakup. The increase in fuel flow has a significant effect on non-premixed injection; the Sauter mean diameter (SMD) decreases from 90.1 to 21.5 μm; the detonation delay time is prolonged with increased equivalence ratio. The detonation with better performance is existed in the non-premixed RDE because of the concentration gradient of the wavefront mixture avoiding the flashback. However, in the premixed RDE fueled by atomizing nozzles, the effect of the flow changes was not prominent. During the detonation initiation process, the droplets tend to be burnt in the deflagration, and nearly 200 ms are required to achieve a stable detonation.