Numerical simulation of a high-pressure hydrogen–air combustion system for aircraft propulsion

This study investigates a hydrogen-fuelled burner representative of civil aviation applications, tested on a high-pressure optical facility. The configuration involves coaxial injection of hydrogen and swirled preheated air. Large-Eddy Simulations are performed for three operating conditions up to 13 bar using a moderately refined mesh and a 15-species mechanism. Results are validated against Particle Image Velocimetry, OH Planar Laser Induced Fluorescence, and OH ∗ chemiluminescence, showing good agreement in flow structure, flame morphology, and NOx trends. A dedicated algorithm based on morphological criteria is employed to systematically identify reaction-zone topologies. This framework is used to analyse the flame response to variations in mass flow rate and pressure. Shear-layer regions are found to dominate fuel consumption despite lower local reactivity. Increasing mass flow rate promotes detached structures, while higher pressure favours stabilisation in hot recirculating regions. The proposed framework provides rare quantitative insight into hydrogen swirl flames at elevated pressure.