Numerical Model for the Development of a Boundary Layer Diffusion Flame over a Porous Flat Plate

摘要

Time-dependent solutions of full Navier-Stokes equations were obtained for gas phase combustion over a porous plate burner using Barely Implicit Flux Corrected Transport (BIC-FCT) algorithms. Unlike the previous boundary layer studies, our solutions are valid near the leading edge as well as the downstream. The simulations show formation of a triple flame structure, upon ignition near the leading edge. The triple flame gets weaker with time as it spreads across the porous plate and finally transitions to a typical boundary layer structure at steady state. The steady state solutions predict a maximum in axial velocity with distance from the solid surface and are similar to the existing experimental observations. The heat feedback from the flame to the surface shows a steep increase near the leading edge followed by a relatively slow decrease with distance from the leading edge. Away from the leading edge, the heat flux profile may be fitted by a power law. This is in sharp contrast to the existing boundary layer theories that show a monotonic decrease in the heat feedback. The results show that 70% of the total heat feedback occurs close (within 3 cm) to the leading edge.