The effects of highly exothermic chemical reaction on a two-dimensional mixing layer

An experimental study of the effect of a highly exothermic chemical reaction on a two-stream mixing layer was performed. One stream was lean premixed cold reactants, while the other stream was hot combustion products that acted as an ignition source for the reactants. Results were obtained for a cold to hot side velocity ratio of 15:5 m/s and cold side equivalence ratios ranging from 0 to 0.8. The effect of increasing the energy release was to cause an increase in the acceleration of fluid on the hot, low-velocity side and, thus, an increase in the growth rate of the layer, movement of the centerline position toward the low-velocity side, earlier interaction of the layer with the wall, and a more rapid decay of the Reynolds stresses from their peak values. The large vortex structures that dominated this flowfield were not qualitatively affected by the exothermic reaction. The layer continued to grow by subharmonic combination until wall effects became important. For equivalence ratios less than the lean flammability limit, chemical reaction was restricted to the region of fluid-dynamic mixing. For equivalence ratios greater than the lean flammability limit, however, the reaction zone extended into the irrotational portion of the reactant stream.