| The fractal properties, i.e., fractal dimension, and inner and outer cutoffs, of premixed turbulent flames are reported by several investigators. A comparison of the measured fractal dimension data as a function of turbulence intensity show that there are significant discrepancies among the reported results. The primary aim of the work reported here is to re-evaluate the fractal properties of the previously obtained flame front images using four different fractal analysis algorithms. In addition, perimeter ratios and flame thicknesses of flame fronts were calculated and their implications in the context of the flamelet model were discussed. These images had been obtained using experimental techniques of laser-induced fluorescence of OH, and Mie scattering on two Bunsen-type burners with diameters of 11.2 mm and 22.4 mm. For the non-dimensional turbulence intensity range of 0.84 < u'/S L < 7 according to the box counting method of fractal analysis, and for 0.84 < u'/SL < 8 according to the perimeter ratio calculations, it was argued in this study that the flamelet model appears valid. The flame front thicknesses calculated based on the maximum gradient of OH concentrations remained at about 0.5 mm for 0.84 < u'/SL< 15. |
