Fire tornadoes are an example of environmental disaster, which causes an enormous damage to the environment and leads to destruction and human fatalities. Fire whirls is a rare but potentially catastrophic form of fire, which dramatically increases the danger of occurring natural and man-made fires and their consequences. They occur in large forest fires, massive fires in cities and major accidents at flammable objects of petrochemical, timber industry, etc. providing full physical modeling of fire whirls is complicated by high risks, costs and complexity of controlling boundary conditions, so the major part of information is obtained through small-scale experiments. The review describes experimental facilities for generating different types of stationary and non-stationary fire vortices and studying their characteristics. We presented and analyzed the results of experiments on the burning rate and the main parameters of fire whirls (height, velocity, temperature).We estimated critical velocity of crosswinds, which yields to generation of the most intensive fire vortices. The features and conditions for the generation of fire whirls during the fires in closed spaces were considered.

The study of the structure was based on a series of distribution by the steps of the thickness. Measurements were carried out in forest shelter belts of the southern part of Central Siberia. Plots were laid on the territory of the Republic of Khakassia (Ust- Abakan, Bay, Shirinsky, Shushensky districts), Krasnoyarsk territory (Minusinsk district) and the Republic of Tuva (Kyzylskiy district). Approximation of distribution rows by diameter has been implemented by two functions: normal distribution and Weibull distribution. With respect to protective forest belts for most forest stands, structure by diameter is more adequately approximated by normal distribution, indicating the symmetry rows. But at this, function of Weibull is characterized by high correlation of its ratios with parameters of plantations, in particular with average diameter and normalized variability. Based on the study of the structure of the plantings in diameter, the optimal agro-technical indicators for the cultivation of plantations presented a variety of wood species, were revealed. It is recommended to divide rows into two groups, before forecasting the series. The first category reflects the influence of the internal (growth) processes: growth, mortality, movement of trees on the steps. These rows can be predicted taking into account the average diameter of tree stand and theoretical density (square of nutrition of individual tree). The second group of rows was formed under the influence of external factors (supplement, renewal, felling, and forest fires).These rows are forecasted using the average diameter and standard deviation of trees. For the prediction of the structure of the stands of Siberian larch, silver birch, Siberian elm and black poplar, model based on the Weibull function, were obtained.

The ingestion in aircraft engines is one of the actual problems related to the flight safety. One of possible reasons of ingestion in the gas-air flow duct of compressor is a formation of vortex core under an air intake on a runway surface during engine working on a stop. Calculations of the solid particles’ motion in wall-free concentrated vortexes, being the analogues of vortex core have been made in this paper. The numerical results have allowed to find peculiarities of behavior for particles with different inertia (different density and sizes) in vortexes of various intensity. Based on calculations and available experimental data a dimensionless criterion had been supposed, which determines the particles’ behavior in concentrated vortex structures. Estimations for maximal time of dynamic relaxation for particles involved in the air intake by vortex cores of different intensities have been made with use of this criterion. The knowledge of particles’ dynamics in the vortex cores formed near the air intake of aircraft engines is necessary to develop the methods to protect them from possible ingestion from the runway to ensure the flight safety.

The results of experimental study of wall-free non-stationary fire vortices are presented. The generation of vortical structures occurred by the burning of pellets of urotropine (hexamethylenetetramine) located on the underlying surface (sheet of aluminum). Unlike most previous research experiments the mechanical twisting devices and the shear air stream to get fire vortex structures were not used. It was assumed that the generation of fire whirls occurred due to the instability of the combustion process. Experimental data on the conditions of fire whirls generation (number of pellets, generation start time and thermal power) and their integral parameters (life time, height and diameter) have been received.