Premixed methane stagnation flames with oxygen enrichment

Chemical kinetics is the science of modeling the steps involved in a chemical reaction at the molecular level. This investigation is concerned with the chemical reactions that occur during combustion. There is ample room for improvement in most presently accepted chemical kinetic models and many reactions are still not modeled. The key to creating and improving chemical kinetic models of combustion reactions is gathering sufficient experimental data and solidifying the foundations upon which more complicated models may be built.;Experiments with oxygen enrichment are then conducted at equivalence ratios not normally within the flammability limits of methane-air mixtures, from the very lean, &phis; = 0.55, to the very rich, &phis; = 1.45. Results show marked disagreement between model and experiment at equivalence ratios far from stoichiometric. These experimental data will allow the chemical kinetic model for premixed methane combustion to be improved---by correcting divergence in the model at very lean and very rich conditions, the model should be improved appreciably over the narrower range of equivalence ratios typically seen in methane-air combustion.;The experimental apparatus that is used to gather data in this study is a stagnation flame burner. Particle image velocimetry, a laser-based flow visualization technique, is used to measure velocity in both the axial and radial directions. The results are analyzed first to confirm the validity of the one-dimensional, axisymmetric model commonly used to describe impinging-jet flow. Experimental results are found to have good agreement with theoretical approximations and numerical models. Tests are then conducted to reproduce previously published data for methane-air flames at lean, stoichiometric and rich conditions in order to prove the reliability of the experimental apparatus. There is agreement between published data and the new experimental results.