Numerical Study on Liquid Fuel Injection by Pylon Injector in Supersonic Flow

A multiphase flow simulation is performed to investigate kerosene liquid fuel injection and breakup characteristics in a cavity-based supersonic combustor with a pylon injector. The homogeneous mixture model, Eulerian-to-Lagrangian transformation method, and adaptive mesh refinement (AMR) method are employed to resolve the breakup process of liquid multi-injections and examine injection phenomena. The large-eddy simulation (LES) model is utilized for turbulence modeling, while the Kelvin–Helmholtz Rayleigh–Taylor (KH–RT) hybrid model and the Abramzon evaporation model simulate secondary breakup and evaporation processes of the liquid fuel. The study analyzes the breakup and mixing efficiency of the liquid fuel under varying injection locations and equivalence ratios. The flow characteristics, droplet distribution, and total pressure loss are evaluated. The fuel distribution considering a specific droplet size is compared with experimental data, showing good agreement. The interactions between the flow around the pylon, the liquid injection location, and the adjacent wall significantly influence fuel distribution and breakup characteristics. In cases of wall-adjacent fuel injection, increased flow stagnation near the wall leads to an extended breakup length, while fuel distribution is further affected by the equivalence ratio and injection positioning. However, the equivalence ratio and fuel injection location have a minimal effect on total pressure loss.