A NUMERICAL INVESTIGATION OF PREMIXED COMBUSTION WITHIN POROUS INERT MEDIA

A numerical investigation of premixed combustion within a highly porou s inert medium is reported. Specifically, results ofa numerical model using detailed chemical kinetics and energy exchange between the flowi ng gas and the porous solid are presented. The current formulation dif fersfrom prior models of this type of combustion in that multistep kin etics is used and a better description of the thermophysical propertie s of the solid is applied in the present model. It was found that the preheating effect increases strongly with increasing convective heat t ransfer and with increasing effective thermal conductivity of the soli d. The convective heat transfer is expected to increase with increasin g number of cells per unit length of porous matrix but the absorption coefficient decreases with increasing cell size and decreasing cell de nsity. Numerical simulations using baseline properties indicate that t he lean limit can be extended to an equivalence ratio of about 0.36for a methane-air flame and that the peakflame temperature is generally h igher than the adiabatic flame temperature. The latter effect is predi cted to be more pronounced at lower equivalence ratios.