Hydrogen is regarded as a key technology for achieving climate-neutral aviation and current efforts include developing combustor concepts based on the widely-used Rich-Quench-Lean (RQL) architecture. However, numerical combustion models commonly used for hydrocarbon fuels to improve aero-engine design fall short in accurately predicting hydrogen combustion. In particular, thermo-diffusive instabilities (TDI) - occurring in lean hydrogen combustion due to differential diffusion and capable of increasing flame speed by up to a factor of four - could not be accounted for by state-of-the-art modeling approaches. Since RQL combustors exhibit a multitude of coupled phenomena such as turbulence-chemistry interaction or flame-wall interaction while chemical reaction and mixing of fuel and air occur simultaneously, development and validation of numerical combustion models using such a complex configuration is unfeasible. In this work, a simplified multi-regime burner (figure 1) is used where similar flame characteristics as in an RQL combustor are observed. Initially, non-reactive simulations of this burner were performed in order to evaluate the capabilities of Large-Eddy Simulation (LES) to predict turbulent mixing, which is essential for the multi-regime configuration. Afterwards, an extension to the Artificially Thickened Flame (ATF) model was implemented into the Rolls-Royce in-house CFD solver PRECISE-UNS, validated in a 2D laminar setup and applied to the reactive multi-regime burner.