Modeling the Non-Premixed Combustion of Methane Enriched by Hydrogen in a Cylindrical Combustor

Abstract

The global shift toward cleaner energy has positioned hydrogen-enriched methane (CH4/H2) as a practical bridge fuel. While it burns more efficiently and produces fewer carbon emissions than traditional hydrocarbons, it introduces operational and safety challenges. Hydrogen’s high reactivity and rapid burning velocity increase risks such as flashback and premature ignition. This study employs Computational Fluid Dynamics to examine the combustion behavior of methane−hydrogen blends in a 2D axisymmetric chamber based on RANS equations. Using ANSYS Fluent 19.1, the research utilizes a validated equilibrium mixture-fraction/PDF framework to ensure accuracy against physical experiments. The simulation framework successfully captures the complexity of non-premixed turbulent combustion by combining a probability density function approach with a realizable k-ε turbulence model. Moreover, this research explores how varying hydrogen concentrations and air mass flow rates, covering the full spectrum from lean to fuel-rich conditions, affect fluid dynamics, turbulence, and the development of recirculation zones. The data show that adding hydrogen fundamentally reshapes velocity fields and thermal profiles, which in turn dictate combustion efficiency and pollutant formation. It has been demonstrated that the optimal blend for combustion performance is the case containing 30% hydrogen. Furthermore, evaluations involving higher-fraction blends (approaching the 70% enrichment range) suggest that configurations exceeding this level necessitate a redesign of the injector near field to mitigate localized heat release and accelerated NOx emissions. By identifying the operational limits for CH4/H2 blends in industrial settings such as steam boilers, this study offers a technical roadmap for engineering more stable, high-performance, and low-carbon energy infrastructure.