Effects of the oxygen mass fraction on the wave propagation modes in a kerosene-fueled rotating detonation combustor

Abstract

In the present study, an experimental model of liquid kerosene-fueled rotating detonation combustor (RDC) was established. The propagation modes of detonation waves were investigated, and the effects of the oxygen mass fraction and the equivalence ratio were analyzed. Dynamic pressure transducers and a high-speed camera were used to capture the pressure signals and combustion field images, respectively. When the oxygen mass fraction was less than 40.5%, there was only one dominant wave frequency in the combustor. However, as the oxygen mass fraction increased to more than 43.6%, a higher dominant wave frequency was generated. To determine the wave propagation modes, high-speed photographic images were transformed and merged chronologically to visualize the trajectory of the detonation waves. Synchronous measurement of the dynamic pressures and high-speed images showed that the reaction zone is coupled to the leading wave front. The two dominant frequencies correspond to the two main modes of the detonation wave, namely the two counter-rotating wave and four counter-rotating wave modes, respectively. It appeared that the wave propagation mode transition was a common phenomenon in the present study, while the wave mode alternated between the single-wave, two counter-rotating wave, and four counter-rotating wave modes. An increase in the number of waves led to a drop in the wave peak pressure, increasing the average light radiation intensity in the combustor. As the equivalence ratio increased, the proportion of the four counter-rotating wave modes decreased. This study also reveals that under the condition of low total mass flux supply, the detonation wave is more probably to exhibit counter-rotating mode.