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Modeling of the processes of the occurrence and spread of forest groundfire with the estimation of the level of flame front heat load

UDC 614.841.41:[614.841.42:630]
Authors Lasuta Gennadiy Fedorovich, PhD in Agricultural Sciences
Goman Pavel Nikolaevich, PhD in Technical Sciences, Associate Professor
Abstract Purpose. The article is devoted to the study of the processes of occurrence and spread of forest ground fires in order to predict the level of heat load from the flame front and improve forest fire prevention measures. The object of the study is a forest ground fire. The subject of the study are the patterns of occurrence and spread of forest ground fire.
Methods. A combination of experimental and analytical methods for investigating the processes of the emergence and spread of forest ground fires was used, the analysis of the obtained results was carried out and compared with the data of a full-scale experiment.
Findings. Experimental data on flame temperature at burning of ground fuel combustible material were obtained, as well as the estimates of the heat load levels realized under conditions of forest ground fire during the formation of large-scale cylindrical flame fronts, which are important for the theory of forest fires. It has been established that the temperature of the flame of a developed fire during the burning of ground cover of coniferous plantations containing moss, lichen, needles, foliage, bark, small branches reaches 1070 K, which is lower than the burning temperature of wood. It was revealed that under conditions of low intensity ground fire a flame front up to 1 m high is formed, unable to ignite ground cover, located behind standard fire barriers in the form of a 1.4 m wide mineralized strip. It was established that at high intensive forest fires with the flame front formation of a cylindrical shape with a height of up to 10 m and the diameter of up to 20 m, the level of heat exposure near the flame front can reach 26 kW/m2.
Application field of research. The results can be used by emergency bodies and units to predict the conditions of occurrence and spread of forest fires.
Conclusions. As a result of the research the regularities of the occurrence and spread of ground fires in natural ecosystems of the temperate climate zone were established. An analytical solution has been obtained that makes it possible to predict the level of heat load from a cylindrical flame front, often realized in conditions of ground forest fires. The methods of full-scale and laboratory modeling revealed patterns of heating of combustible forest material when exposed to thermal radiation from the flame front.
Keywords forest ground fire, forest combustible material, flame front, heat radiation, burning
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