Thermo-diffusive Effects on Scalar Dissipation Transport on Lean Hydrogen Flames

This work analyzes the scalar dissipation rate (SDR) transport in hydrogen/air flames in different equivalence ratios (lean, stoichiometric and rich) under different turbulent conditions, in which thermo-diffusive instabilities have an impact on flame dynamics. While different studies in the literature have examined the effects of curvature and strain on SDR transport, it has only been done so through stoichiometric methane flames. Moreover, the known topological instabilities of lean hydrogen flames, exhibit suppressed wrinkling and its impact on SDR transport is unknown. To do so, 2D DNS simulations were conducted in the aforementioned stoichiometric conditions, since the computational time for 3D DNS simulations often prohibits parametric studies of this kind. This work evaluates the effect of flame stoichiometry, and how it modulates the interplay between turbulence, diffusion and chemical kinetics. This work, challenges existing SDR transport frameworks by resolving the role of thermo-diffusive instabilities in hydrogen combustion.