Parameters, limits, attenuation, and suppression of detonation in mixtures of an explosive gas with chemically inert microparticles

Abstract

UDC 534.222Chapman-Jouguet parameters and the cell size of a detonation wave in mixtures of an explosive gas with chemically inert particles have been calculated. The algorithm of calculation of the minimum mass and characteristic dimension of a particle cloud ensuring successful suppression of detonation in the gas has been proposed. The calculation results are in good agreement with the available experimental data. The influence of the initial composition of the gas on the efficiency of suppression of the detonation wave has been analyzed. The issue of the dependence of the concentration limits of detonation on the mass fraction of particles has been investigated. It has been established that the increase in the concentration of the condensed phase leads to a narrowing of the existence domain of detonation and that the propagation of the detonation wave becomes impossible when the concentration of the particles is fairly high.Introduction. Injection of chemically inert particles is an efficient method of control of detonation processes in gaseous mixtures. The theory of propagation and suppression of a detonation wave (DW) in gases with chemically inert particles is far from completion. It is only the influence of the size, density, and concentration of the particles of the wave parameters that has theoretically been investigated until recently [1][2][3][4][5][6][7][8][9][10][11][12]. Theoretical modeling was mainly one-dimensional. Two-dimensional modeling of detonation in mixtures of a gas with particles has been carried out in [9,11,12]. According to the results of theoretical investigations, an increase in the concentration of the condensed phase and a decrease in the particle size and the density of the particle material improve the efficiency of suppression of the wave by chemically inert particles. These results correlate with available experimental data.At the same time, the minimum total mass of the condensed phase and the spatial length of a particle cloud, which cause wave suppression, have not been calculated, except for [13]. The influence of the mixture's thermodynamic parameters (in particular, heat capacity, temperature, and melting heat) has not been analyzed. The issue of the criterion of successful suppression of a DW in reactive gases with particles remained open, too.In [14], we proposed an algorithm for the calculation of the parameters of a Chapman-Jouguet wave in mixtures of a gas with chemically inert microparticles and the method of evaluation of the relative size of a detonation cell. By analogy with gaseous detonation, we proposed the criterion (based on a comparison of the channel diameter and the cell size) for the limit of multifront detonation in such heterogeneous media. We calculated the minimum mass of the particles and the characteristic dimension of the cloud that are necessary for suppressing detonation. We were the first to analyze the influence of the thermodynamic parameters of the particles on the process of detonation suppression. Calculations of the DW velocity as a f...

Inert nanoparticle suppression of gas explosion in the presence of obstacles

“…Besides Mg(OH) 2 , other particles have been brought into wide use as ame retardants. 21,31,34,37 In order to further explore the inuence of nanoparticle material on suppressing behaviors against methane-air explosion, three different particle materials, i.e. Al(OH) 3 , Mg(OH) 2 , and SiO 2 , were used respectively, in which the given particle density (100 g m À3 ) and the averaged size (30 nm) were considered.…”

“…[12][13][14][15][16][17][18][19][20] From the literature, it is known that, for xed particle density, more intense suppression is obtained for smaller particles. So far, due to the complicated process of explosion suppression, literature studies concerning the evaluation of explosion suppression using powders were essentially carried out on micro-sized particles, 21 and thus there is little information concerning nanoparticle suppression characteristics. Actually, nanoparticles have higher specic surface area and are easy to contact with and absorb free radicals near the combustion reaction region, which directly reduces the combustion reaction intensity and in turn depresses the explosion ame speed and pressure wave.…”

Mathematical modeling of the detonation wave and inert particles interaction at the macro and micro levels

“…It has also been established that the addition of inert particles to an explosive mixture contributes to the suppression of detonation [3][4][5][6][7][8][9][10][11][12]. The interaction between detonation waves and inert particles have been studied mainly in one dimension, resulting in estimates of the effect of volume fraction, particle diameter, and their thermophysical properties on the ability to attenuate and suppress detonation.…”