The study investigates the transition process from a ground fire to a crown fire. The studies were carried out in seminatural conditions on the territory of the Base Experimental Complex (BEC) of the IAO SB RAS. Previously, reconstruction of the forest canopy was carried out. The emergence of a crown fire occurred due to the transition of a ground fire to the bottom layers and further to the crowns of trees. Non-contact diagnostic methods (IR thermography) were predominantly used to measure combustion front parameters.
The article presents the results of a series of mesoscale experiments to study wildfires and their impact on the atmosphere. A change in meteorological parameters, a significant increase in fluctuations of the refractive index, speed of sound and temperature in the vicinity of the experiment, which are a reflection of the occurrence of turbulent processes in the atmosphere, were established, experimental data were obtained on changes in the concentration of methane and carbon dioxide as a result of a fire, and data were obtained on the mechanism of occurrence of crown fire.
A study of the conditions of ignition of a layer of wood as a result of exposure to burning particles formed during a fire has been carried out. Research results show that the ignition process is influenced by the wind speed, the size and number of particles falling on the underlying surface.
The paper presents results of an experimental study of the propagation characteristics of grassland fire front, its effect on meteorological parameters and the emission of gaseous combustion products. As a result of the study, it was found that the seat of fire of a small-scale combustion lead to an increase in air temperature by 2-3 degrees and a decrease in relative humidity by 5%. The highest pulsations amplitude of the wind velocity vertical component of 12 m/s was recorded using a weather station installed at a relatively low height. These pulsations are due to the strong inhomogeneous of the upward flow of combustion products.
The paper represents the experimental study of combustion over the surface of a vertically-mounted oriented strand board panel under different environmental conditions. An infrared camera was used to obtain the sequences of thermograms characterizing the heat flow pattern on the surface of the sample during vertical combustion and determine the velocity of the combustion wave under laboratory and field conditions. In addition, the change in the angle of the combustion front was estimated depending on time.
The paper presents the experimental study results on the effect of heat flux emitted by a standard source on the charring and ignition characteristics of pine wood. Using a new method of setting the experiment with the recording of IR image, the charring rate and depth of the wood as a result of heat exposure from a standard source. The influence of several fire retardants on the charring rate and depth of samples is analysed. The use of noncontact IR diagnostics allows one to analyse the charring rate of pine wood depending on the intensity of heat flux and to draw up the temperature field.
The paper describes the study of the ignition of wood samples treated with a flame retardant in the presence of different ignition sources (firebrands, pine needle litter) under the laboratory conditions, and to obtain data on fire resistance of wood samples exposed to heat. The charring depth of the wood samples was determined depending on the type of wood, as well as on the type of the fire retardant used. The experimental results show that fire retardants significantly increase the protective properties of wood exposed to firebrands.
The development of devices for localization and extinguishing of wildland fires based on knowledge of the flame structure, including the drying zone, heating, pyrolysis, mixing with oxygen in the air, using relatively small energy disturbances (shock waves), which minimizes the damage caused to the environment have been represented. Using of the considered technical solutions leading to increase the effectiveness and efficiency of activities to combat wildland fires has been shown.
This paper provides the results of the laboratory studies the interaction of smoldering firebrands (pine bark and branches) with fuel bed that is a litter of pine needles. The wind speed and the density of fuel bed were varied during the experiments. The results have shown that the increase in the wind speed leads to the increase in the probability of the fuel bed ignition by firebrands of the same size, and the increase in the density of fuel bed leads to the decrease in the probability of that. The probability of ignition of fuel bed by the branches, all other things being equal, is found to be higher compared to the bark firebrands due to the combustion heat.
The paper describes the use of IR thermography methods in the investigation of peat fires. The temperature distribution on the peat surface was obtained using a local source of ignition in the form of a glowing spiral located under the sample in the laboratory conditions. These data can be used to determine the horizontal propagation of the peat fire front.
The impact of spot fire on wood different-shaped samples (flat and cylindered sample) is studied under laboratory conditions. Using thermal imagery and a thermocouple method, the temperature is determined on the surface of the test samples after the impact of the fire front; the possibility of wood ignition is analyzed for the chosen parameters of the experiment.
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