High-Fidelity Numerical Simulation of an Anchored Hydrogen-Air Flame in a Dual-Swirl Co-Axial Injector

Hydrogen-fueled combustion systems are a promising pathway toward deep decarbonization in aviation and power generation, but challenges remain in accurately predicting flame stabilization, turbulent mixing, and NOX emissions. This study performs high-fidelity Large Eddy Simulations (LES) of the attached hydrogen/air Flame A in the HYdrogen LOw NOₓ (HYLON) dual-swirl coaxial burner, a canonical configuration developed for CFD model validation. The simulations employ detailed H₂/NOₓ finite-rate chemistry, adaptive mesh refinement, and a two-equation LES turbulence model under experimentally matched boundary conditions. Comprehensive validation is conducted using available measurements of velocity fields, fuel distribution, and combustor exit temperature. The LES accurately reproduces the dominant hydrodynamic and thermochemical features of the flame, including the dual-swirl flow structure, V-shaped diffusion flame stabilization, and canonical state-space behavior. Detailed analysis of instantaneous and time-averaged fields reveals the strongly mixing-controlled nature of the flame and identifies the shear-layer mechanisms governing heat release and flame anchoring. Overall, the results provide new insight into hydrogen diffusion-flame structure, stabilization, and demonstrate a validated computational framework to support the design of low-emission hydrogen combustors.