Детонационные процессы во фронте горения растительных горючих материалов

Abstract

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.