Influence of Surface Reaction on Near-Wall Premixed Flame Behavior

Abstract

To investigate near-wall flame behavior including effect of the surface reaction, two-dimensional direct numerical simulations (DNS) of methane/air, hydrogen/air and n-heptane/air premixed ignition and propagation between two parallel walls are conducted under several thermochemical conditions. From the DNS results, the flame front position defined by the OH gradient, and the flame displacement speed defined by the temporal evolution of the position are evaluated. The present analysis revealed following characteristics. (i) The flame speed takes a local minimum value near the wall. (ii) Under the conditions where the wall temperature equals unburnt gas temperature, this local minimum value corresponds to the laminar flame speed of the initial thermochemical condition. (iii) These characteristics do not depend on the ignition position, equivalence ratio, fuel types and presence/absence of surface reaction.