Effects of Heat Losses on Flame Shape and Quenching of Premixed Flames in Narrow Channels

Unsteady premixed flames in narrow channels of different heights with adiabatic or isothermal walls are investigated numerically. It is assumed that the flame chemistry is modeled by an one-step overall reaction which simulates the reaction of a stoichiometric acetylene-air mixture. The numerical results show that, In the case of plane ignition, both channel height and thermal boundary condition affect flame structure formation. The increase of channel height is favor of the formation of tulip-shaped flame. Under a given channel height, a transition from the tulip-shaped flame to the mushroom-shaped flame occurs as the flame propagates from one end of channel to the other for isothermal cold walls. In addition, some parameters such as quenching temperature, quasi-extinction space and heat-supply rate are introduced to analyze the intrinsic relationships between flame propagation and quenching in narrow channels, which is called the criterion of flame propagation and quenching in narrow channels.