Experimental evaluation of the fractal geometry of flamelets

The fractal character of flamelets in premixed turbulent V-flames is evaluated through combined tomographic and time-series light scattering measurements. Fractal dusts and curves generated by the intersection of lines and planes with flamelets surfaces are observed. Algorithms for evaluating fractal character from the experimental data are described and discussed. The results, obtained for several different flame conditions, indicate that flamelets can be represented by fractal surfaces with a fractal dimension and inner and outer cutoffs to fractal behavior. The outer cutoff is several times larger than the integral scale in the reactant flow, while the inner cutoff is an order of magnitude larger than the Kolmogorov scale. The fractal dimension which is implied for the flametet surface from these measurements is approximately 2.1 which is well below the expected value of approximately 2.37. Several reasons for this difference are offered including low absolute turbulent intensity and low turbulence Reynolds number.