Numerical study on droplet evaporation and propagation stability in normal-temperature two-phase rotating detonation system

摘要

A numerical study is carried out on the droplet-laden two-phase rotating detonation wave of kerosene/ oxygen-enriched air at normal temperature. Two types of combustors without and with the inlet mixing section are constructed to illustrate the effect of inlet mixing section on the combustion characteristics of two-phase rotating detonation wave. In the inlet mixing section, a preheating zone is formed after the reverse oblique shock wave induced by the rotating detonation wave, and its important role on the droplet evaporation is analyzed. The parameter sensitivity of rotating detonation wave propagation stability to the average droplet diameter d_0 is further discussed. Results show that the droplets mainly evaporate after the detonation front in the combustor without inlet mixing section, and the reaction heat release is completed in a short distance, which propels continuous propagation of the detonation wave. When d_0 gradually increases, the droplet evaporation distance increases, and the coupling between the incident shock and reaction is continuously weakened, finally resulting in the detonation quenching. In the combustor with inlet mixing section, a preheating zone is induced close to the contact surface by the reverse oblique shock wave. A large number of droplets evaporate in this zone, and generate sufficient mixture of fuel vapor and oxidizer in front of detonation wave to maintain the detonation propagation. Priority to the combustor without inlet mixing section, the droplet evaporation relies less on the inlet high-temperature airflow with the assistance of preheating zone, and thus the wave propagation stability can be enhanced and the rotating detonation wave can sustain for a wider range of d_0. The present analysis provides a new understanding of two-phase rotating detonation systems.