Hydrogen enrichment effects on combustion dynamics and emissions in a hydrogen/methane combustor

The transition to hydrogen-enriched fuels in gas turbine combustors is critical for achieving sustainable energy goals, yet traditional combustor designs struggle to accommodate hydrogen's rapid combustion properties. This study investigates the combustion characteristics of a methane/hydrogen blend (0–40 % H₂ by volume) in a lean premixed W501F FlameSheet™ Combustor under constant heat input. Utilizing a partially premixed flamelet model coupled with turbulent shear stress transport k-omega and flamelet-generated manifold (FGM) approaches, the analysis focuses on flame dynamics, emission trends, and operational stability. The combustor's innovative design, inspired by the backward-facing step phenomenon, generates dual recirculation zones at the bend and pilot regions, acting as flow accelerators to stabilize flames and prevent flashback by maintaining a low-fuel-concentration buffer zone between injectors and ignition points. Results demonstrate robust flame stabilization at up to 40 % hydrogen, beyond which pilot-region instabilities emerge. The external tornado-shaped flame enveloping an independent internal flame enables precise temperature and load control. Hydrogen enrichment reduces CO₂ and CO emissions nonlinearly, with a 16.7 % CO₂ reduction at 40 % H₂. However, dual temperature peaks at the combustor outlet suggest distinct heat transfer implications for turbine blades, warranting further study. These findings provide actionable insights for designing hydrogen combustors that balance performance and durability.