NUMERICAL INVESTIGATION OF WATER FILM EVAPORATION ON THE SURFACE OFF FOREST FUEL

The results of numerical studies of heat transfer processes at the evaporation of liquid film on a surface of typical forest fuel (FF) are presented. Values of the desired thickness of the liquid film at different sizes of the heated surface layer of the typical FF (birch leaves, pine and spruce needles) for suppression of the thermal decomposition reaction (end of burning) are shown. It is established that at the thickness of the surface layer FF is not more than 0.06 m in the process of suppressing the thermal decomposition reaction evaporates the water layer with a thickness Le less than 1 mm. This result shows that the “cooling” of the nearsurface FF layer quite substantially smaller liquid film thickness as compared with the actually emerging in extinguishing fires. The characteristic times of suppression of the thermal decomposition reaction (end of burning) of typical FF disease when exposed to water films with minimum dimensions. It is established that at the thickness of the near-surface FF layer less than 0.06 m need time not more than 1.5 minutes. Approximation expression showing redundancy water supply into the combustion zone “local dropping”, in which the surface of FF can form a liquid film thickness significantly greater than the required set (minimum) value Le are formulated.