A comparison of complex chemistry mechanisms for hydrogen methane blends based on the Sandia / Sydney Bluff-Body Flame HM1

The paper presents numerical simulations of the Sandia / Sydney bluff-body stabilized flame HM1 [1] fueled with a mixture of 50 vol.% hydrogen and 50 vol.% methane. A variety of 7 detailed reaction mechanisms ranging from a skeletal mechanism with 16 species to a comprehensive mechanism with 118 species are tested. The reactive flow regime is solved by an unsteady RANS approach. Turbulence chemistry interactions are treated by the Eddy Dissipation Concept. A comparison of the different reaction mechanisms is carried out based on the axial temperature distribution, radial species distributions, the integral exhaust gas species mass flows and the required computation time. The results are compared to the available experimental data. Aside from the 2 basic reaction mechanisms there is generally good agreement between the experimental and the numerical results. In addition, differences among the more elaborated reaction mechanisms are small. For the chosen approach, a 30 species mechanism could be identified that achieves nearly the same results as the well-established GRI 3.0 at 40% less computational effort. A 24 species mechanism shows only small deviations at 80% less computational effort, which makes it highly attractive for large parametric studies