Differential Diffusion Effect in H2/NH3 Non-Premixed Flames and Flamelet-Based Models

The primary focus of this work is to examine the differential diffusion effect for flames fueled by H2/NH3.For a non-premixed turbulent flame, two Direct Numerical Simulations (DNS) have been implemented in two-dimensional domain, one is considering the differential diffusion (DD) of each species pair and the other assumes Unity Lewis Number (ULN).Two Flamelet libraries are created based on ULN and Mixture Averaged Diffusion (MAD) assumptions, they are validated through priori tests based on the DNS results.Significant difference between the two DNS cases, the DD case is more resistible for quenching than ULN case, meaning ULN assumption for DNS is not suitable.Furthermore, significant variations in the chemistry states are also evident in ULN library results, suggesting that differential diffusion should be considered in the Flamelet model, additionally, equal diffusivities is inappropriate for an H2/NH3-fueled flame, while MAD library exhibits more consistent chemistry states with the DD DNS.