CONVECTION-DIFFUSION CONTROLLED LAMINAR MICRO FLAMES

Small laminar diffusion flames (flame height similar or equal to 2-3 m m) established by a fuel jet issuing into a quiescent medium are inves tigated. It was found that for these flames buoyancy effects disappear ed as the flame size decreased (Fr much greater than 1), and diffusive transport of the fuel was comparable to the convective transport of t he fuel. The effect of buoyancy on these flames was studied by examini ng the flame shape for horizontally oriented burners. A phenomenologic al model was developed (based on experimentally determined flame shape s) to compare diffusion and convection transport effects. Finally, the flame shapes were theoretically determined by solving the conservatio n equations using similarity methods. It was seen that when the axial diffusion (in momentum and species equations) terms are included in th e conservation equations, the calculated flame shape is in better agre ement (as compared to without the axial diffusion term) with the exper imentally measured flame shape.