Three-dimensional direct numerical simulation of hydrogen-air turbulent premixed flame has been conducted to develop and verify SGS combustion model for turbulent premixed flames. The conventional SGS combustion model, which represents the SGS turbulent burning velocity as a monotonically increasing function with respect to SGS turbulence intensity, fails to represent the filtered DNS data. SGS flame surface area of turbulent premixed flame is hardly approximated by the function of SGS turbulence intensity, and shows strong correlation with GS strain rate of turbulent velocity field. In place of the conventional model, a new SGS combustion model has been proposed under assumptions of fractal characteristics of flame fronts and the scale separation of turbulence. The predicted results by the proposed model coincide very well with DNS results.
