Numerical case study of stage-resolved gliding-arc plasma-assisted kerosene ignition in an oxygen-deficient cavity-strut afterburner

Igniting liquid kerosene in an afterburner is challenging under hot and oxygen-deficient inflow conditions because atomization, evaporation, pyrolysis, radical generation, and flame-kernel establishment must occur within a short convective time scale. This study investigates the stage-resolved ignition mechanism of a gliding-arc plasma igniter in an integrated cavity-strut afterburner operating at T = 1050 K, Y O 2 = 14 %, and strut trailing-edge Mach number of Ma st = 0.45. A high-fidelity Eulerian-Lagrangian framework is developed to couple spray evolution, evaporation, kerosene pyrolysis, finite-rate turbulent combustion, and experimentally constrained plasma energy and species source terms. The ignition transient is resolved into six sequential stages, revealing that the dominant contribution of gliding-arc plasma shifts among aerodynamic droplet modification, thermal fuel preparation, active-species-driven chemical initiation, and local oxygen enrichment during ignition. Jet momentum promotes droplet breakup near the igniter, while the arc thermal field increases pyrolysis-product concentrations by one to two orders of magnitude compared with the unexcited baseline. During the early ignition period, most of the sampled flow remains reaction-limited ( Da < 1, where Da is the Damköhler number), whereas the plasma-excited region locally reaches Da ≈ 10, enabling self-sustained ignition. The flame kernel is transported from the cavity recirculation across the shear layer into the strut wake, and its evolution is governed by the cavity-strut flow topology rather than the arc trajectory. These findings clarify the stage-dependent role of gliding-arc plasma in liquid-fuel ignition and provide a physical basis for plasma-igniter optimization and miniaturization.