NUMERICAL STUDY OF STRUCTURES OF LAMINAR OPPOSED FLOW PREMIXED METHANE-HYDROGEN-AIR FLAMES AT LOW STRAIN RATE

Numerical investigation of laminar counterflow premixed methane-hydrogen-air flames at a low strain rate is presented. Simulations are carried out with a numerical model incorporated with C2 chemical mechanism having 25 species and 121 reaction steps, and with an optically thin radiation submodel. The numerical model is validated using the experimental data reported in the literature in terms of temperature and species concentrations in flames from opposed flow premixed methane-air and hydrogen-air streams. Parametric studies are performed for opposed flowing methanehydrogen and air mixtures. A premixed methane-hydrogen and air with a rich mixture equivalence ratio (1.75) flows from the top duct, and one having a lean mixture equivalence ratio (0.25) flows from the bottom duct. The volumetric fraction of hydrogen in the fuel mixture has been varied from 20 to 80%. The strain rate used in the present study is kept constant at 50 s -1. Variation of velocity, temperature, species concentrations, and net reaction rates of oxygen, methane and hydrogen along the axis for various cases are presented and discussed in detail. Double flame zones are observed for all the cases. The addition of hydrogen to the rich side stream is seen to be effective in modifying the extents of both reaction zones. The reaction rate of methane is seen to be enhanced with the addition of hydrogen. � 2011 by Begell House, Inc.