Flashback of H2-enriched premixed flames in perforated burners: Numerical prediction of critical velocity

Hydrogen has been identified as a potential tool for decarbonizing various industrial sectors by replacing natural gas while maintaining the combustion-based conversion system. However, due to its high reactivity, hydrogen is prone to flashback, making it essential to implement safety measures for its efficient use in practical appliances. This study investigates the flashback of different H2/CH4 mixtures at an equivalence ratio φ = 0.8 and proposes a numerical model to predict the critical flashback velocity for laminar premixed flames. The model considers the conjugate heat transfer between the gas phase and the burner plate. To overcome the computational cost needed to resolve both gas and burner heating, different time steps are employed for the fluid and the solid domains. Two flashback regimes are identified depending on the H2 content. The results suggest that using the laminar flame speed alone is inadequate for designing the safe operation of practical premixed burners.