This paper concerns with the problems of cooling down of various high-voltage electric power devices of the megawatt range.When flowing around the current-carrying and other elements of these devices a formation of non-stationary vortices can take place.Therefore, a detection and visualization of vortex structures appearing at the coolant flowing through channels with the complicated geometry is an important task.The generation of whirlwind structures (non-stationary vortices) was performed above this substrate surface (aluminum alloy sheet) by the unstable air stratification obtained by heating it up from below.We have used the mcm sized particles of magnesia deposited on the substrate surface to visualize the generated free non-stationary vortices.The frame-by-frame view of recordings obtained by the direct video-registration at various thermal modes allowed performing of the qualitative analysis of the spatio-temporal structure of non-stationary vortices and obtaining a lot of their important integral parameters (visible height, diameter, lifetime, quantity of vortices, base motion velocity, etc.).There had been considered physical basements of processing of flow patterns obtained by the PIV method with the use of the measurer of fields of velocities POLIS (Russian "ПОЛИС", the instrument is developed by the S.S. Kutateladze Institute for Thermophysics of the Siberian Branch of RAS, Novosibirsk) in order to recover the fields of instantaneous velocities of vortex structures.The results of the visualization of free non-stationary vortices obtained by the direct video filming and vector fields of instantaneous velocities, obtained by the PIV (Particle image velocimetry) method, have been presented.The developed technique of visualization and diagnosis of free non-stationary vortices can be used for development of the state-of-the-art cooling systems of high-power electric devices.

This paper is aimed to demonstrate an opportunity of the generation of nonstationary wall-free fire whirls under laboratory conditions without using mechanical swirling devices and to estimate their integral parameters. A simple experimental facility, making possible the generation of concentrated fire vortex structures by means of combustion of solid fuel (urotropine) arranged symmetrically on a metallic underlying surface, is described. With the use of photography, some novel data on the probability of generation of fire whirls depending on the experimental mode have been obtained.

It is demonstrated that free concentrated fire whirls can be physically modeled if the outer circulation is absent. Vortex structures were generated when hexamethylenetetramine pellets, located axially on a substrate (aluminum sheet) burned. The first data on specific features of fire whirl formation and some integral parameters (the lifetime, height, and diameter) were obtained using video shooting.

An experimental plant for the display of fire vortices is developed. An analysis of the nonstationary flame obtained as a result of burning of solid fuel is carried out. Nonstationary fire vortex structures are identified by means of an infrared thermograph. An algorithm for establishing a fire vortex from a thermogram and determining its geometric and temperature characteristics is proposed.

The possibility of the principle of physical simulation of free concentrated fire vortices without using a forced twist is demonstrated. Vortex structures were generated during combustion of urotropine (hexamethylenetetramine) pellets placed on the underlying surface (aluminum sheet). The first data on the features of the occurrence of fire vortices were obtained by photographs. Estimates of some integral parameters of the generated fire vortex structures (lifetime, height, and diameter) are carried out.

Разработана экспериментальная установка для визуализации огненных вихрей. Проведен анализ нестационарного пламени, получаемого в результате сжигания твердого горючего. С помощью инфракрасного термографа идентифицированы нестационарные огненные вихревые структуры. Предложен алгоритм фиксации огненного вихря по термограмме и определения его геометрических и температурных характеристик.The experimental installation for visualization of wall-free fire vortices has been developed. The analysis of the non-stationary fire generated by burning of solid fuel has been carried out. An identification of the non-stationary fire vortex structures occurrence by means of infrared thermograph was done. An algorithm of the fire vortex fixation by thermogram and its geometry/temperature parameters determination has been suggested.

Продемонстрирована принципиальная возможность физического моделирования свободных концентрированных огненных вихрей без использования принудительной закрутки. Генерация вихревых структур происходила при горении таблеток уротропина (гексаметилентетрамина), располагаемых на подстилающей поверхности (лист алюминия). С использованием фотосъемки получены первые данные, касающиеся особенностей процесса возникновения огненных вихрей. Проведены оценки некоторых интегральных параметров генерируемых огненных вихревых структур (время жизни, высота, диаметр).

The principal possibility of tornadoes physical modeling in vitro without use of mechanical twisting devices has been shown. The results of experiments on studying related to opportunities of whirlwinds control are given. The offered and approved method of impact on whirlwinds (tornado), consisting in an arrangement of obstacles in the form of vertical grids in a way of vortex structures distribution, has been described. The method efficiency is verified in vitro by studying of specified obstacles influence on dynamics of the free non-stationary whirlwinds having structure, similar to real tornadoes. The main physical mechanisms related to impact on tornadoes of the offered passive and active method have been briefly considered.

The possibility in principle of physical simulation of concentrated fire vortices in laboratory conditions without using mechanical swirling devices is shown.