Large-eddy simulation of lean hydrogen-methane turbulent premixed flames in the methane-dominated regime

摘要

The application of large-eddy simulation (LES) to the prediction of H_2-enriched lean methane-air turbulent premixed combustion is considered. A presumed conditional moment (PCM) subfilter-scale combustion model is coupled with the flame prolongation of intrinsic low-dimensional manifold (FPI) chemistry tabulation technique. The LES and PCM-FPI modelling procedures are then applied to the prediction of laboratory-scale axisymmetric Bunsen-type turbulent premixed flames. Both premixed methane-air and H_2-enriched methane-air flames are considered and the predicted solutions are examined and compared to available experimental data, The enriched flame has 20% H_2 in terms of mole fraction and lies in the methane-dominated regime of hydrogen-methane mixtures. The LES simulations predict similar qualitative trends to those found in the experiments for flame height and curvature. The addition of H_2 decreases the flame height and broadens the curvature probability density functions, which show a Gaussian-type shape centred around zero. Moreover, the enriched flame displays a higher degree of wrinkling with sharper ridges of negative curvature and larger pockets of positive curvature. Overall, the proposed treatment for the PCM-FPI combustion model, in terms of progress variable and tabulated data, seems to perform well for the H_2-enriched methane flame in the methane-dominated regime.