DNS Investigation of Near-Wall Flame Behavior Including Radical Quenching Effect*

The laminar flame displacement speed changes drastically near a wall, and this dependency could be applied to the experimental measurement of the laminar flame speed. In a previous experimental study, temporal variation of the flame displacement speed of the methane-air premixed combustion propagating towards a wall was measured, and it was concluded that the flame displacement speed just before impinges on the wall corresponds to laminar flame speed approximately. In this study, to investigate the above features more detail, direct numerical simulation (DNS) is performed under several conditions, by considering radical quenching process on the wall. Following results are obtained: (i) displacement speed of the premixed flame propagating perpendicular to a wall have a local minimum; (ii) where the wall temperature equals unburnt gas temperature, the local minimum value almost corresponds to laminar flame speed of a corresponding thermochemical condition regardless of ignition position, equivalence ratio, and fuel types; (iii) these characteristics do not depend on the presence/absence of radical quenching processes.