High-Fidelity Simulations of an Ultra-Compact Trapped Vortex Combustor with Liquid Fuel Spray

Ultra-compact trapped vortex combustors are promising for aviation applications. The trapped vortex combustor concept utilizes cavities that lead to recirculation zones, such that a flame can stabilize without being directly exposed to the main flow. This allows for an efficient combustion process with superior fuel-air mixing and increased stability, which makes the trapped vortex combustor particularly promising for compact engines in aviation. In this work, we present high-fidelity simulations of an ultra-compact trapped vortex combustor that has been developed and studied experimentally at the University of Illinois, Urbana-Champaign (Shim et al., 2024). The combustor operates on liquid F-24 fuel injected into two cavities, and forward and backward inlets supply air for establishing efficient mixing and strong cavity vortices. Simulations in this work are conducted at a pressure of 3 bar and an overall equivalence ratio of 0.15. The simulations are performed with the low-Mach adaptive mesh refinement reacting flow code PeleLMeX. The analysis focuses on combustion characteristics and flame stabilization. Significant interaction of fresh fuel with recirculated gases is observed. Statistics of key quantities are presented with respect to flow field and mixing characteristics. In addition, an analysis based on extracted flamelets is presented that provides further insight into features of the flame stabilization and combustion process with respect to mixing and flow field characteristics.