Lifted laminar diffusion flames-experiments and analysis.

Abstract

Experiments on axisymmetric and two-dimensional lifted laminar diffusion flames have been conducted to obtain the height of lift as a function of flow parameters. The results are correlated on the basis of simple dimensional analysis. The two-dimensional case has been investigated analytically by solving conservation equations. Noting from the experiments that the flame is stabilized in the shear layer, the conservation equations are solved using the standard boundary layer approach for variable density flows. A major departure concerns the energy equation, where the axial and lateral gradients are kept together along with the reaction kinetic term. Though single-step reaction kinetics is invoked, the parameters are chosen to reproduce the flame speed of the gaseous fuel used in the experiments. The height of lift is shown to confirm experimental correlation, in addition to indicating a pressure dependence given by: m=0.44m = 0.44m=0.44 because of the reaction kinetic term. The results are argued to be important in modeling composite propellant combustion.