Представлены результаты дистанционного зондирования дымового шлейфа над модельным очагом природного пожара с использованием специализированного лидара, принцип работы которого основан на эффекте увеличения обратного рассеяния, регистрирующего оптическую турбулентность. Расстояние до очага горения составляло 1600 м, площадь модельного пожара варьировалась: 1, 9 и 25 м2. Установлено, что во время горения лидар фиксировал повышение эхосигнала в основном приемном канале, регистрирующем аэрозольное рассеяние и турбулентную компоненту, относительно эхосигнала в дополнительном приемном канале, регистрирующем только аэрозоль. Ширина дымового шлейфа не превышала 20 м, повышение основного эхосигнала наблюдалось сразу за шлейфом в интервале расстояний от 0 до 600 м. В данном эксперименте шлейф теплого дыма действовал как фазовый экран, который изменял когерентную структуру лазерного пучка. После завершения интенсивного горения температура внутри шлейфа быстро понижалась и лидар фиксировал только содержание аэрозоля. Появление аэрозольной и турбулентной составляющей в эхосигнале, отражающих повышение концентрации аэрозоля и интенсивности турбулентности, однозначно указывает на очаг горения. Проведено сравнение лидарной оценки значений структурной характеристики показателя преломления Cn2на высоте 10 м над очагом горения с данными ультразвуковой метеостанции АМК-03 на высоте 3 м и результатами моделирования низового природного пожара, опубликованными ранее. Применение турбулентного лидара является перспективным способом обнаружения малых очагов горения, в том числе бездымного или с низким выбросом конденсированных продуктов горения. This paper presents the results of an experiment on remote sensing of a smoke plume over a model fire with the use of a specialized lidar based on the backscatter enhancement effect and detecting optical turbulence. Burning was 1.600 m away, and the area of the model fire varied from 1, 9 and 25 m2. It was found that during combustion, the lidar recorded an increase in the echo signal in the main receiving channel, which registers aerosol scattering and the turbulent component, relative to an echo signal in the additional receiving channel, which registers only the aerosol. The width of the smoke plume did not exceed 20 m, an increase in the main echo signal was observed immediately after the plume in the distance range up to 300 m. In this experiment, a plume of warm smoke acted as a phase screen that changed the coherent structure of the laser beam. After the completion of intensive combustion, the temperature inside the plume rapidly decreased and the lidar recorded only the aerosol content. The appearance of two signs in the echo signal – an increase in the aerosol concentration and turbulence intensity – clearly indicates a source of burning. The lidar estimation of the values of the structural characteristic of the refractive index Cn2at an altitude of 10 m above the combustion focus was compared with the data of the ultrasonic meteorological station AMK-03 at an altitude of 3 m and results of simulation of a grass-roots fire published earlier.

В докладе представлено описание экспериментальной установки и результаты экспериментальных исследований тушения модельного очага горения растительных горючих материалов (РГМ) с применением ударных волн и последующим охлаждением РГМ водой. Показана эффективность комбинированного тушения очага горения по сравнению с тушением распыленной водой, заключающаяся в снижении почти в 2 раза расхода воды для гарантированного тушения. Определен критерий гарантированного тушения очага горения по максимальной температуре поверхности РГМ. The report presents a description of the experimental setup and the results of experimental studies on extinguishing the model combustion center of plant combustible materials (PCM) using shock waves followed by cooling the PCM with water. The effectiveness of the combined extinguishing of the combustion center compared to the spraying of water is shown, which consists in reducing the water consumption for guaranteed extinguishing by almost 2 times. A criterion for guaranteed extinguishing of the combustion center is determined based on the maximum surface temperature of the PCM.

В докладе представлены результаты эксперимента дистанционного зондирования дымового шлейфа и конвективной колонки над модельным очагом природного пожара с использованием специализированного лидара, работающего на эффекте увеличения обратного рассеяния и регистрирующего оптическую турбулентность. Установлено, что во время горения лидар фиксировал повышение эхосигнала в основном приемном канале, регистрирующем аэрозольное рассеяние и турбулентную компоненту, относительно эхосигнала в дополнительном приемном канале, регистрирующем только плотность аэрозоля. Проведено сравнение лидарной оценки значений структурной характеристики показателя преломления Cn на высоте 10 м над очагом горения с данными ультразвуковой метеостанции АМК-03 на высоте 3 м и данными моделирования низового природного пожара, опубликованными ранее. The report presents the results of an experiment on remote sensing of the smoke plume and the convective column above a model natural fire source using a specialized lidar that operates on the principle of enhanced backscattering and records optical turbulence. It was found that during combustion, the lidar recorded an increase in echo signal in the main receiving channel, which registers aerosol scattering and the turbulent component, relative to the echo signal in the additional receiving channel, which only records aerosol density. A comparison of lidar estimates of the structural characteristic of the refractive index Cn at an altitude of 10 m above the fire source with data from the ultrasonic meteorological station AMK-03 at an altitude of 3 m and previously published modeling data for surface natural fires was carried out.

В докладе представлены результаты экспериментальных исследований модельных очагов пожаров на локальные характеристики атмосферы. Эксперименты проводились в полунатурных условиях на Базовом экспериментальном комплексе ИОА СО РАН. Зарегистрировано, что вследствие распространения модельного пожара происходит формирование индуцированной атмосферной турбулентности, проявляющееся в изменении структурной характеристики флуктуаций показателя преломления, изменении локальных метеопараметров, выброс в атмосферу газообразных и конденсированных продуктов горения. Показано, что на расстоянии до 500 м от очага горения наибольшая концентрация конденсированных продуктов горения регистрируется на высоте 10-20 м. Установлено, что в результате горения в окрестности эксперимента преобладают фракции аэрозолей с диаметром частиц менее 0.65 мкм. The report presents the results of experimental studies of model fires on the local characteristics of the atmosphere. The experiments were carried out in semi-natural conditions at the Basic Experimental Complex of the IOA SB RAS. It has been recorded that due to the spread of a model fire, induced atmospheric turbulence is formed, manifested in a change in the structural characteristics of fluctuations in the refractive index, changes in local meteorological parameters, and the release of gaseous and condensed combustion products into the atmosphere. Gorenje It has been shown that at a distance of up to 500 m from the gorenje gorenje, the highest concentration of condensed combustion products is recorded at an altitude of 10-20 m. It was found that as a result of gorenje, aerosol fractions with a particle diameter of less than 0.65 microns predominate in the vicinity of the experiment.

This paper presents the results of an experiment on remote sensing of a smoke plume over a model fire with the use of a specialized lidar for detecting optical turbulence, which is based on the backscatter enhancement effect. Burning was 1600 m away, and the area of the model fire varied from 1, 9, and 25 m2. During combustion, a lidar echo signal in the main receiving channel, which records aerosol scattering and the turbulent component, increased relative to an echo signal in the additional receiving channel, which records only the aerosol. The width of the smoke plume did not exceed 20 m; an increase in the main echo signal was observed immediately after the plume at distances of up to 600 m. In this experiment, a plume of warm smoke acted as a phase screen which changed the coherent structure of a laser beam. After the completion of intensive combustion, the temperature inside the plume rapidly decreased and the lidar recorded only the aerosol content. Appearance of two indicators in an echo signal, an increase in the aerosol concentration and strengthening of turbulence, clearly points out to a burning source. The lidar estimate of the structure characteristic of the refractive index C_n^2 at an altitude of 10 m above the combustion focus was compared with data of AMK-03 ultrasonic meteorological station at an altitude of 3 m and results of simulation of a grass-roots fire published earlier.

В работе представлены результаты исследований турбулентности в пламени и в окрестности очага горения при модельных степных и верховых пожарах, проведенных в период 2019-2023 гг. на БЭК ИОА СО РАН. Получены спектры изменения температуры воздуха и масштабы индуцированной атмосферной турбулентности в окрестности фронта модельного пожара. Показано, что в результате интенсивного тепловыделения в окрестности очага горения происходит локальное изменение метеопараметров и параметров атмосферы, отражающих протекание турбулентных процессов. The paper presents the results of studies on turbulence in the flame and in the vicinity of the combustion center during model steppe and crown fires conducted from 2019 to 2023 at the BAC of the Institute of Atmospheric Optics SB RAS. The spectra of air temperature changes and the scales of induced atmospheric turbulence in the vicinity of the model fire front have been obtained. It has been demonstrated that as a result of intense heat release around the fire source, there is a local change in meteorological parameters and atmospheric characteristics that reflect the course of turbulent processes.

В работе проведено экспериментальное исследование влияния внешних пульсаций давления малой интенсивности на факел пламени метана. В качестве метода исследования процессов, протекающих в факеле пламени, использовалась ИК-диагностика. Исходя из анализа поля температуры были получены соответствующие спектры изменения температуры в пламени для различных режимов внешнего воздействия. Было получено, что на соответствующих спектрах присутствуют, помимо основной частоты, которая соответствует частоте внешнего воздействия, в спектре присутствуют две гармоники, амплитуда которых уменьшается с ростом частоты. In this work, experimental research on the influence of external low-intensity pressure oscillations on a methane flame torch is conducted. Infrared diagnostics were used as the method to study the processes occurring in the flame torch. Based on the temperature field analysis, corresponding temperature change spectra in the flame for various external impact modes were obtained. It was found that in the corresponding spectra, in addition to the main frequency corresponding to the frequency of the external influence, there are two harmonics present, whose amplitudes decrease with increasing frequency.

A mathematical model of the ignition of wooden structures by “hot” particles is proposed. The spatial problem is considered in a three-dimensional formulation in Cartesian coordinates. It was found that the ignition of wood is determined by the processes of drying, pyrolysis of the dry reagent, and by the reactions of oxidation of carbon monoxide, methane, and hydrogen. The dependences of the wood ignition delay time on the initial temperature of the “heated” particles and their quantity were found. In some cases, a qualitative comparison of the calculation results with the known data was noted.

На базе большой аэрозольной камеры Института оптики атмосферы им. В.Е. Зуева СО РАН и установки «Генератор горящих и тлеющих частиц» было проведено исследование по оценке средней скорости в окрестности выходной части установки. В качестве измерительного оборудования использовалась (2d) лазерная доплеровская измерительная система для диагностики газожидкостных потоков ЛАД-05. Используя оригинальные методы и алгоритмы обработки данных, проанализирована характерная скорость воздушного потока в зоне генерации частиц, а также проведено качественное сравнение с данными по скорости частиц, полученными методом ИК-термографии. On the basis of a large aerosol chamber of the V.E. Zuev Institute of Atmospheric Optics SB RAS and the installation "Generator of burning and smoldering particles", a study was conducted to assess the average velocity in the vicinity of the output part of the installation. A (2d) laser Doppler measuring system for the diagnosis of LAD-05 gas-liquid flows was used as measuring equipment. Using original data processing methods and algorithms, the characteristic air flow velocity in the particle generation zone was analyzed, and a qualitative comparison was made with particle velocity data obtained by IR thermography.

A description of the experimental setup and the results of experimental studies of combined extinguishing of a model source of combustion of vegetative combustible materials (VCM) with the use of shock waves and subsequent cooling of VCM with water are given. The effectiveness of the combined fire extinguishing compared to the extinguishing with sprayed water has been shown. It has been established that a decrease in the surface temperature of VCM below 503 K should be considered as a criterion for guaranteed extinguishing of a combustion source.

— This paper presents the analysis and generalization of the results of studies of turbulence in flame and in the vicinity of a combustion source during model steppe and crown fires performed at the Basic Experimental Complex of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in the period from 2019 to 2022. The spectra of air temperature changes and the scales of induced atmospheric turbulence in the vicinity of the front of a model fire are obtained. The ranges of air temperature pulsation frequency corresponding to the inertial and dissipative sections of the energy spectrum are found for a steppe fire; dissipative processes start running at an altitude of 10 m at wavenumbers with log k > 1.58 and the corresponding pulsation frequency f > 3 Hz; no dissipative processes are observed at an altitude of 3 m. During a model crown fire, turbulent processes in the atmosphere correspond to the inertial part of the energy spectrum at an altitude of 10 m; dissipative processes hardly manifest themselves.

The paper presents the results of studies of diffusion combustion of gaseous methane in the presence of external pressure pulsations with low amplitude on the flame plume. The analysis of the temperature field and the stabilization time of the combustion mode has been carried out. It is established that the presence of pressure pulsations leads to characteristic changes in the temperature field, which are expressed by a growth of the temperature pulsation amplitude, corresponding to the frequency of external influences. A characteristic time for stabilizing the combustion regime from the moment when there is no external influence to their appearance is determined.

The interaction of a firebrand shower with some types of combustible building materials and wood structures was studied experimentally. The heat flux generated by firebrands was determined, and the temperature fields of the most heat-stressed sections of the structures were analyzed. The heating rate of samples was estimated based on infrared thermography data. Under the selected experimental conditions, the bench sample was found to be the most resistant to ignition. Estimation of the near-surface temperature of the bench element showed that after 15-min continuous exposure to firebrands, the temperature in the zone of maximum accumulation of firebrands did not exceed 130°C. The wood fence model was found to be most prone to ignition (ignition delay time more than 15

In this study, a theoretical formulation of the ignition and combustion of the wood layer by burning and smoldering firebrands has been considered. The effect of the firebrands’ length, distances between firebrands and their geometrical parameters on the heat exchange with the wood layer and the ignition process were analyzed. With a decrease in firebrand size, ignition of wood is possible with a decrease in the distance between the firebrands. With an increase in firebrand size at the same distance between them, the ignition regime becomes possible albeit with a longer delay time Δt. With a decrease in the distance between the firebrands, the ignition of wood is possible with an increase in Δt. As a result of mathematical modeling of the process, the following processes are noted: the heat stored in firebrands of small sizes is insufficient to initiate the ignition process; the temperature in the wood layer, due to conductive heat exchange, slightly increases at first, before beginning to decrease as a result of heat exchange with the surrounding air and the wood layer; intensive heat exchange with the environment of small size firebrands leads to the end of firebrand smoldering and its cooling; and, if the firebrand size reaches a critical value, then the pyrolysis process begins in the area adjacent to it.

Представлен анализ и обобщение результатов исследований турбулентности в пламени и в окрестности очага горения при модельных степных и верховых пожарах в экспериментах, проведенных в период с 2019 по 2022 г. на Базовом экспериментальном комплексе Института оптики атмосферы СО РАН. Получены спектры изменения температуры воздуха и масштабы индуцированной атмосферной турбулентности в окрестности фронта модельного пожара. Установлены диапазоны частот пульсации температуры воздуха, соответствующие инерционному и диссипативному участкам энергетического спектра, для модельного степного пожара. Показано, что диссипативные процессы начинают формироваться на высоте 10 м при волновых числах k таких, что lgk > 1,58 и соответствующей частоте пульсаций ƒ > 3 Гц; на высоте 3 м диссипативные процессы не наблюдаются. При модельном верховом пожаре на высоте 10 м турбулентные процессы в атмосфере соответствуют инерционному участку энергетического спектра, а диссипативные процессы практически не проявляются. This paper analyzes and generalizes the results of studies of turbulence in flame and in the vicinity of the combustion source during model steppe and crown fires in the period from 2019 to 2022 at the Base Experimental Complex of Institute of Atmospheric Optics SB RAS. The spectra of air temperature changes and the scales of induced atmospheric turbulence in the vicinity of the front of a model fire are obtained. For a steppe fire, the air temperature pulsation frequency ranges corresponding to the inertial and dissipative sections of the energy spectrum are found; dissipative processes begin to form at an altitude of 10 m at wave numbers with lgk > 1.58 and the corresponding pulsation frequency ƒ > 3 Hz; at an altitude of 3 m, dissipative processes are not observed. During a model crown fire, turbulent processes in the atmosphere correspond to the inertial part of the energy spectrum at an altitude of 10 m, and dissipative processes practically do not manifest themselves.

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.

This paper presents a short-term experimental results pressure surge effect on the pyrolysis plant combustible materials (PCM) zone. It was found that as a result of exposure there is the combustion flame mode interruption, causing a decrease in the PCM elements surface temperature involved in combustion, which during further forced cooling leads to a combustion complete cessation.

Представлены результаты экспериментального исследования воздействия ударной волны на пламя при горении растительных горючих материалов. Ударная волна формировалась с помощью ударной трубы с различными насадками и источником энергии от порохового заряда. Для регистрации воздействия ударной волны на зону пиролиза применялись методы высокоскоростной ИК термографии в узкополосном диапазоне длины волны 2,5–2,7 мкм. Установлено, что при применении расширяющихся насадков в результате воздействия ударной волны на зону пиролиза происходит детонация продуктов пиролиза, которая приводит к прекращению пламенного горения. Much attention is currently being paid worldwide to improvement of existing and developing new effective ways to fight effectively natural fires, which occur annually in different countries and on a variety of landscapes. Given the annual increase in the number of wildfires and the often catastrophic consequences from them, it can be stated that the existing methods of firefighting are not effective enough. The methods used to extinguish large fires are usually based on the discharge of water by aircraft and the involvement of a large amount of manual labor of firefighters. This work is devoted to the study of the issue of extinguishing a natural fire by the impact of a shock wave on the burning zone. At present, the question of the interaction of the compaction shockwave with the flame during the combustion of plant combustible materials remains practically unstudied. Existing works in the field of shock waves impact on the fire front are limited to estimates of disruption of combustion conductors and formation of mineralized band. Modern research tools and methods allow to record and visualize the rapid processes, including in the flame. In particular, modern methods of infrared thermography make it possible to study both the temperature field in the flame and the structure of flow in it. Based on the original methods and approaches for application of high-speed infrared thermography developed at Tomsk State University, this work presents the results of an experimental study of the shock wave effect on the flame during combustion of plant flammable materials. A shock tube with different nozzles and an energy source from a gunpowder charge were used to form the shock wave. The impact of the shock wave on the pyrolysis zone was recorded in the narrow band infrared wavelength range of 2.5–2.7 μm. It has been established that the impact of the shock wave on the pyrolysis zone, when expanding nozzles are used, results in the detonation of pyrolysis products, which leads to the cessation of flame combustion and subsequent decrease in the surface temperature of plant combustibles below the autoignition temperature. This effect leads to a break in the chain of transformation and energy release during combustion. The obtained result should be considered as a fundamental basis for the development of new effective means of extinguishing large natural fires based on the impact of a shock wave.