Combustion on heterogeneous media - A critical phenomenon

We report a series of experiments on combustion spreading on different heterogeneous media. The propagation of the flame front on the random lattice is studied under quiescent conditions and in the presence of wind. The criticality of the transition spreading/non-spreading of the combustion has been experimentally brought out without and with wind. Percolation concepts explain the values of the experimental thresholds under conditions where no wind is present. In the case of wind-driven flame fronts, the results appear to be covered by directed percolation.