Effects of the Lewis Number on Premixed Flame Shape Formation in Narrow Channel

摘要

Propagation of unsteady premixed flames in narrow channel with adiabatic wall is numerically investigated, and effects of Lewis number on flame shape formation are discussed particularly. Navier-Stokes equations are solved using finite volume formation. The continuity equation and pressure are solved using the SIMPLE algorithm. It is assumed that the flame chemistry is modeled by one-step overall reaction which simulates the reaction of stoichiometric acetylene-air mixture. The numerical results show that, mushroom-shaped flame is the preferred shape as Lewis number is greater than or equal to unity, while tulip-shaped flame is the preferred shape as Lewis number is less than unity. It is also shown that the enhancement of mass diffusion contributes to the formation of tulip-shaped flame. The drawn conclusion will be a necessary complement to the mechanisms of tulip-shaped flame formation.