| The interaction of a premixed laminar flame with its self-induced boundary layer in a channel was numerically simulated using the two-dimensional, reacting, Navier-Stokes equations. A two-species chemical model was implemented which simulates a stoichiometric acetylene and air mixture. The channel was configured with the ignition at a closed end and the opposite end open. As the flame propagated, it induced a flow ahead of it, which created a boundary layer along the wall of the channel. The effects of altering the ignition method, viscosity, Lewis number, and the boundary condition at the wall were investigated. The results of this research indicate that the boundary layer growth followed the classical solution of Stokes' First Problem with the addition of an acceleration term. The boundary layer growth is self-similar in local time. Local time is defined as the time at a point starting from when the initial pressure wave, generated by the flame movement, reaches that point in the channel. Since the pressure waves produced by the flame motion were represented, this research represents a direct numerical simulation of the acoustic interaction of these waves with the flame. The results also indicated that the ignition method and wall boundary condition greatly effect the flame propagation. The flame propagation speed was greater when a spark ignition was implemented as opposed to a planar ignition. This was due to the flame developing a greater burn area in a shorter time. When the wall temperature was held constant, the propagation speed was greatly reduced over the flame in the adiabatic wall simulations. Unlike the adiabatic wall case, the flame speed oscillated in time. For the isothermal wall case, regions of reversed flow formed and dissipated near the wall. The formation of these reversed flow regions corresponded to the periods of flame deceleration. |
