Numerical study on the mixing and combustion characteristics of a liquid kerosene jet in a scramjet combustor

Abstract

We numerically investigate the mixing and combustion process of a kerosene jet injected into a scramjet combustor with dual-cavity at different global fuel equivalence ratios using a compressible two-phase flow large-eddy simulation based on the Eulerian–Lagrangian approach. The results indicate that the calculated wall pressure distribution is basically consistent with the experimental result. The high-temperature zone and intermediate product CO distribution zone shown by the numerical simulation agree with the flame position observed by the experiment. When the global equivalent ratio is 0.149, the combustion is in the weak combustion mode. The flame only exists in the downstream cavity, which is mostly the premixed flame. The combustion efficiency is low, and the corresponding total pressure loss is small. When the global equivalent ratio is 0.187, the combustion is in the intense combustion mode, and the flame has a strong instability characteristic. The numerical simulation reproduces the flame flashback phenomenon that the flame backpropagation from the downstream region of cavity C1 to the upstream region of the liquid jet. During the flame flashback process, the flame gradually changes from premixed flame dominated to premixed flame and diffusion flame jointly dominated. In the weak combustion mode, the interaction between flame and droplet is weak, and droplet evaporation is less affected by combustion. While in the intense combustion mode, droplets evaporate more violently, the spray penetration depth increases, and some liquid droplets are transported upstream of the jet by the wall reflux zone.