Hybrid RANS/LES Simulation of the Fuel Injection and Mixing Process in a Supersonic Combustor with Cavity Flame-Holder

摘要

Flow field and mixing process around a cavity flame-holder in a supersonic combustor with the transverse fuel injection has been simulated by using hybrid RANS/LES simulations. The interactions between the the transverse fuel jet and cavity, and the effect of the assistant injection inside the cavity have been investigated, in order to know the flow characteristics and fuel distribution before the spark igniting. The results show that, two pairs of counter-rotating vortices (CRVs) formed downstream the transverse injection; the lower CRVs develop around the wall and flow into the cavity shear layer, and finally, they induce a three dimensional recirculation zone in the cavity. This three dimensional recirculation generates a wider span wise diffusion when an assistant injection is used inside the cavity. The assistant injection could not only change the fuel distribution around the cavity but also intensify the interaction of the cavity shear lay with the main fuel jet plume by raising the shear layer towards the main flow. The raised shear layer would result a thicker subsonic zone downstream the cavity. The present work is beneficial to explain the enhanced ignition performance by the assistant injection found in the experiments.