Effect of Turbulence on Stability of a Flat Plate Boundary Layer Diffusion Flame

Effects of turbulence on instability of a leading flame edge of a diffusion flame formed in a boundary layer over a flat plate with uniform fuel injection have been studied experimentally. Two different types of stability limit are identified. One is observed when the air flow approaching the leading flame edge is laminar. The stability limit of this type depends both on the approaching air flow velocity and fuel injection velocity. The other type is observed when the leading flame edge is strongly affected by the turbulence. In this case, the stability limit depends on neither approaching air flow velocity nor fuel injection velocity but only on turbulent intensity in the approaching air flow. When the leading flame edge becomes unstable due to turbulence, the turbulence appears to affect not the chemical reaction but mainly the diffusion process.