Turbulent Boundary Layer Flashback in Lean Hydrogen Flames

Hydrogen is a carbon-free fuel that can be utilized in gas turbines to minimize emissions. One of the main obstacles of using hydrogen is boundary layer flashback, a phenomenon that occurs when the flame propagates faster than the boundary layer flow and can damage gas turbines. In this study, we investigate boundary layer flashback in hydrogen–air mixtures using direct numerical simulations. The main simulation domain is a straight channel with a hot wall near the end to stabilize the flame before triggering flashback. Turbulent inlet flow conditions come from an auxiliary non-reacting channel simulation. Equivalence ratios are increased until the nominally stable flame experiences flashback. The flame structure and flashback propensity, are analyzed through the lens of a recently developed critically strained flashback model. In particular, the relationship between extinction limits and flashback are studied. This work aims to advance predictive models for flashback, contributing to safer combustor designs for hydrogen and alternative fuels.