LES of Stable Combustion and Lean Blow-out in a Mach 2 Cavity Flameholder

This study presents high-fidelity Large Eddy Simulations (LES) of supersonic combustion in a Mach 2 cavity flameholder over the full stable fueling region from 40 to 200 slpm. The simulations employ Finite Rate Chemistry LES with the Z70 ethylene-air mechanism, the Localized Dynamic k-equation model, Partially Stirred Reactor turbulence-chemistry interaction model, conjugate heat transfer, and thermal radiation modeling is utilized. The FRC-LES results are validated against RC-19 experimental data, including PIV, hyperspectral imaging, laser induced breakdown spectroscopy, OH-PLIF imaging and broadband chemiluminescence imaging, and analyzed using synthetic diagnostics derived from CFD fields. Increasing fueling rate drives a transition from a compact cavity-stabilized flame to an elongated shear-layer-stabilized configuration, accompanied by widening of the cavity shear layer, downstream flame an-choring, intensified unsteadiness, and mixed combustion modes revealed by the modified Takeno flame index. The simulations capture key trends in flame structure, heat release, and stabilization mechanisms, providing insights critical for scramjet combustor design under realistic operating conditions. Data analytics models based on cluster-ing algorithms shed further lights on the intra-cavity flow, mixing and combustion processes.