Abstract Methyl methacrylate (MMA) is the main pyrolysis product of the widely used polymer polymethyl methacrylate; therefore, a compact mechanism of MMA oxidation is of interest for CFD modeling of flame propagation over this polymer. A reduced mechanism of MMA combustion consisting of 263 elementary reactions involving 66 species was developed based on a detailed chemical-kinetic mechanism of MMA

Abstract A general model describing the combustion of mixed gases is proposed, which accounts for the chemical work and assumes a single chemical reaction. An energy equation is written for an arbitrary mixture of fuel/oxidizer/combustion product. The combustion of an H2/O2 mixture is considered on the basis of the model. Modeling is carried out for two options: with and without account for the dependence

Abstract Ignition and combustion of a homogeneous stoichiometric methane–air mixture under simultaneous local thermal and photochemical impacts, resulting in the formation of either O\(_{2}(a^{1}\Delta _{g})\) molecules or O atoms, are numerically simulated. A two-dimensional unsteady multicomponent approach with the use of the known detailed kinetic mechanism of methane oxidation, which takes into

Abstract A scanning electron microscopic study has shown that exposure of spheroplastics based on an organosilicon elastomer to a microsecond shock-wave pulse causes the formation of whisker structures up to 10 \(\mu\)m long. Whisker structures are formed on the surface of fractured microspheres. Their formation is facilitated by the metallization of the surface of glass spheres. The paper presents

Abstract A computational and experimental study of the passage of a gasless combustion wave through a wedge-shaped inert obstacle was performed. The stability of the transient combustion process to a change in the thermophysical and geometric parameters of the obstacle and the energy-kinetic parameters of chemically active layers was studied. By the region of stable transient combustion process is

Abstract The ignition of methane–air mixtures with additives of ClF5, ClF3, OF2, and H2O2 (additive content in the mixtures \(\le\)1%) is studied by numerical simulation. The ignition temperature of the mixtures is determined as a function of the initial pressure and additive content. It is shown that the introduction of the additives into the mixture leads to a significant decrease in the ignition

Abstract Natural fragmentation of steel cylinders with different charge sizes is investigated, and the correlation of different cylinders is proposed. The Mott fragment distribution has some obvious shortcomings, including the difficulty of accurately determining the number of fragments. Besides, there is no unified and convenient method to describe the fragmentation behavior of shells with different

Abstract The dependence of the diameter of a porous carbon particle on stationary temperature at various gas mixture pressures is analyzed. The cases of particle self-ignition in a heated nitrogen–oxygen mixture and forced ignition in a cold nitrogen–oxygen mixture that lead to quasi-stationary combustion, followed by spontaneous extinction, are considered. It is shown that the combustion temperature

Abstract A method of obtaining detonation nanodiamonds from tetryl by means of blasting the latter in a water shell with the explosive/water mass ratio of 1/(10–14) is developed. The proposed method ensures the yield of the target product in the amount of 6–7 wt.% of the initial mass of the reagent with the content of nanodiamonds in the resultant batch mixture equal to 57\(\,\pm\,\)6 wt.%. It is demonstrated

Abstract Effect of K2CO3 and KCl additives on the process of high-temperature oxidation and ignition of conglomerates of powdered boron and aluminum particles and on the critical conditions for the ignition of particle–gas mixtures of these metals is studied experimentally. It is revealed that the mixtures of boron and aluminum particles covered (encapsulated) with salts ignite at temperatures lower

Abstract Two approaches to describing an expanding spherical flame are compared. Processing of a large amount of experimental data shows that the approach using as a small parameter a parameter proportional to the strain rate gives a lower accuracy approximation than the approach using as a small parameter the ratio of the flame thickness to the radius of curvature.

Abstract Composite propellants are tested using the quench particle collection bomb (QPCB) for the pressure ranging from 2 to 8 MPa to estimate the particle size distribution of aluminum agglomerates from quenched combustion residues emerged out from the burning surface. The major ingredients included in the propellants are ammonium perchlorate (AP), aluminum (Al), hydroxyl-terminated polybutadiene

Abstract In this paper, confined explosions of HMX-based aluminized explosives in a spherical chamber are studied. The effects of aluminum particles on the afterburning reaction and explosive performance are obtained by changing the size of the particles and the gas environment. The results show that the concentration of oxygen in air is not sufficient to support complete combustion of aluminum particles

Abstract A composite material based on the Ni–Al–C system is synthesized by the method of an electrothermal explosion at a pressure of 96 MPa. During the electrothermal explosion in a reactive powder medium (Ni + Al + C), a Ni- and Al-based melt is formed, in which carbon dissolves. In the process of crystallization of the final product, carbon, due to its low solubility in NiAl, is located on the

Abstract Combustion of mechanically activated mixtures in 2Co–Ti–Al and Co–2Ti–Al is investigated, and alloys based on them are obtained by self-propagating high-temperature synthesis (SHS). Microstructural, X-ray, and differential-thermal studies are performed. A Heusler phase Co2TiAl-based alloy is obtained for the first time by means of mechanical activation. Conditions for the mechanical activation

Abstract A CCDS2000 detonator for acetylene, ethylene, propylene, and a multicomponent methylacetylene–allene fraction (MAF) fuel is used to perform experiments on measuring the detonation velocity and recording a detonation front cell in a tube 26 mm in diameter and 2 m in length. The experiments are carried out at atmospheric pressure in stoichiometric mixtures diluted by nitrogen to air concentrations

Abstract Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is extensively employed in military weapons as the main constituent of HMX-based polymer-bonded explosives (PBXs). It is known that the safety of PBXs is closely related to their microstructures. Discontinuities in PBXs, such as micron-sized pores, air bubbles, and interfaces between the explosive crystal and polymer bonds, may transform

Abstract Influence of coal micronization on air-blown conversion of pulverized coal fuel is under study. On the basis of these experiments, computational fluid dynamics methods are used to perform simulation determining the conditions of the process under study. Conversion of coarse coal in a medium of combustion products of fine coal with the following parameters: a flow rate ratio of primary and

Abstract A model of nonstationary homogeneous nucleation of boron oxide vapor in chemically reacting gas mixtures is developed. The model is used to perform a numerical study of homogeneous nucleation of boron oxide vapor in Laval nozzles with different geometric configurations. Typical sizes of boron oxide condensation nuclei and their concentrations are determined. The potential barrier of nucleation

Abstract RDX containing a small amount of single-walled carbon nanotubes is obtained by the method of co-precipitation out of a solution. The detonation of this composition is studied by an electromagnetic method of mass velocity measurement and by a high-resolution electroconductivity method. A clearly expressed chemical spike is observed. Preliminary indications of reaction acceleration in the presence

Abstract This paper presents the method and results of an experimental study of the ignition characteristics of samples of high-energy materials by multimode laser radiation. A uniform distribution of the radiation flux density over the end surface of a cylindrical sample is obtained by its rotation around the axis of symmetry with a given angular velocity of rotation. The effect of convective heat

Abstract An experimental method for determining the critical pressure perturbations leading to acoustic instability in combustion chambers of liquid-propellant rocket engines has been developed and used to estimate the stability of the working process. The method involves statistical processing of recorded noise pressure pulsations near the natural resonant frequency range for all normal modes of acoustic

Abstract Difference in the molar masses of a combustible gas and its combustion products has a strong effect on a flame temperature and a burning rate. Instead of a molar mass difference, one may consider a heat capacity difference at a constant pressure. There are two heat sources in a combustion zone. One of them is chemical, and the other one is similar to heat release (heat absorption) during a

Abstract The effect of SO2 on the oxidative conversion of hydrogen and methane in a wide range of temperatures of 400–1500°C at a pressure of the reacting mixture of 1 atm was studied by numerical kinetic analysis. The analysis showed that sulfur dioxide could have both accelerating and retarding effects on the oxidative conversion of hydrogen and methane, which is due to the participation of SO2 and

Abstract Dependence of the combustion of a Ti + C granular charge on a granule size is experimentally studied. It is revealed that the burning rate of a granular mixture of all fractions used in the work is higher than the burning rate of a bulk-density powder mixture. It is shown that, with a decrease in the granule size, the burning rate of the charge in the absence of gas decreases due to an increase

Abstract This paper presents the results of a study of the dynamic compression of plastic-bonded PETN using the split Hopkinson pressure bar (SHPB) technique. The test procedure and some aspects of this technique are described. The advantages of the SHPB technique over drop-weight tests of explosives are briefly discussed. In the experiments, the strain rates were 7500–12 000 s-1. Force–strain and

Abstract Pipe sticking is one of technical challenges in the drilling industry that has a major impact on the drilling efficiency and well costs. In order to eliminate deep water stuck pipe hazards, a new type of the jet cutter cartridge is designed. The main structure of the cartridge is a linear shaped charge including hydrogen-based emulsion explosives and copper tubes. During the detonation process

Abstract New data on parameters of combustion and detonation of two-fuel mixtures of methane and hydrogen with oxygen and air are presented. The data are obtained with variations of both the ration between CH4 and H2 and also the ratio between the fuel components and oxidizer. Results for the critical energy of detonation initiation, characteristic size of detonation cells, detonation velocity, and

Abstract Combustion of vapors of a flammable liquid whose temperature is below the flash point is under study. In this case, the flame propagates along the surface of the liquid due to being heated by combustion products. The velocities of an oxidizer moving towards the flame, which propagates at velocities comparable to the laminar burning rate of premixed hydrocarbon flames, are measured. The measurements

Abstract A new characteristic of detonating explosives is proposed—the deceleration curve of the von Neumann spike. An example of plotting such a curve on the basis of experimental data obtained at the All-Russian Scientific Research Institute of Technical Physics for detonating plastic-bobded TATB is given.

Abstract Large explosion-proof chambers are manufactured using cylindrical shells made of sheet metal by rolling and welding with addition of longitudinal and circumferential seams. In this case, one should make a choice of steel with increased strength or ductility. In this regard, this work presents the results of a study of the reaction of such 09G2S and 10KhSND steel shells to dynamic loading.

Abstract The structure and phase composition of a material obtained via SHS in the combustion of a 87% Ti + 13% B powder mixture with the addition of Si3N4 is under study. The phase formation mechanism in this system is discussed. It is established that the material contains 64% of the TiB phase with an orthorhombic structure and 36% of the solid boron solution in titanium (\(\alpha\)-Ti[B]). The boron

Abstract Data on the most important combustion and detonation parameters, such as wave velocities, pressures and temperatures of products, specific energy release of mixtures are presented for saturated hydrocarbons C\(_{n}\)H\(_{2n + 2 }\) [from methane (\(n\) = 1) to eicosane (\(n\) = 20)] and unsaturated hydrocarbons C\(_{n}\)H\(_{2n}\)[from ethylene (\(n\) = 2) to eicosene (\(n\) = 20)], also methanol

Abstract The heat of combustion and the enthalpy of formation of 7,7′-bis(terfurazan[3,4-b:3,4′-d:3″,4″-f]azepine (I) and 1,1′-dioxide-7,7′-bis(terfurazan[3,4-b:3,4′-d:3″,4″-f] azepine (II), were experimentally determined. Product I was studied by X-ray diffraction analysis, and its crystallographic characteristics were determined. The efficiency of using compounds I and II as components of solid composite

Abstract Based on advanced numerical simulation technologies, such as the birth and death of element technique, large displacement technique, and fluid-solid coupling mechanism, and combined with the strain rate effect of concrete and steel materials, a complicated finite element model of a TNT–air–slab system is set up using the nonlinear explicit dynamic finite element analysis software LS-DYNA.

Abstract The combustion, explosion, and detonation in hybrid systems containing gas mixtures of CH4/air, CH4/O2, and O2/coal particles up to 200\(\mu\)m in size with a volume-averaged density of up to 700 g/m3 were studied on a vertical shock tube. X-ray diffraction patterns of the initial coal powder and coal samples subjected to high-temperature waves were analyzed. Data were obtained on the structure

Abstract In studies of the structure of the reaction zone in detonation waves of high explosives, it is common to measure the mechanical characteristics of the flow—the histories of particle velocity, pressure or density. Experience has shown that in such profiles, it is difficult to identify the chemical reaction zone. These distributions, as a rule, are distorted when the flow interacts with measuring

Abstract Regimes of continuous spin detonation and continuous multifront detonation of a gas–droplet mixture of gaseous hydrogen and liquid oxygen in a plane–radial combustor (internal diameter of 100 mm and external diameter of 300 or 200 mm) with exhaustion toward the periphery are obtained for the first time. The detonation front height of the gas–droplet mixture is greater than that of the gas

Abstract In this paper, the so-called REDIM–DTF sub-grid scale combustion model is proposed to improve the well-known dynamically thickened flame (DTF) combustion model by combining the DTF modeling strategy with the reaction-diffusion manifold (REDIM) chemistry table, which is generated from a detailed reaction mechanism. The new model is then used to calculate two lean premixed swirling flames in

Abstract HMX can be detonated by an exploding bridgewire (EBW) or a slapper. Direct HMX detonation by an electrical arc has not been demonstrated. This paper shows that the shock from a 99% worst-case lightning current (200 kA and 500 ns rise time) can detonate standard-density HMX at elevated temperatures (i.e., HMX in the most sensitive \(\delta\)-phase at a temperature above 177°C) and that the

Abstract The detonation of mixtures of highly dispersed PETN with sodium bicarbonate with a mass fraction of the latter up to 90% is investigated using radio interferometric method and electron-optical method NANOGATE-22 along with a method using a polyvinylidene fluoride pressure sensor. The experimental results obtained indicate the possibility of the existence of various detonation regimes in mixtures

Abstract A flake aluminum powder (f-Al) is prepared by a bi-directional rotation mill method using a spherical aluminum powder (s-Al) as a raw material. Then, these two kinds of aluminum powders are used to prepare ammonium perchlorate-based composite modified double-base (AP-based CMDB) propellants. The properties of two kinds of AP-based CMDB propellants, such as the thermal decomposition performance

Abstract This study experimentally confirms the intensification of kerosene combustion in the case where a mixture simulating steam reformation products in a model combustion chamber with a supersonic velocity of the flow at the inlet. It is shown that the used mixture has a higher chemical activity than ethylene. The use of steam reformation products of hydrocarbon or synthetic propellants in schemes

Abstract This paper introduces a simple and new correlation between the impact sensitivity and activation energy for pyrotechnic compositions where both the fuel and oxidizer are inorganic in nature. The database consists of various drop height (impact sensitivity) and activation energy values obtained from in-house experimentation and various literature studies. This paper also proposes a method to

Abstract The dispersion of oxidized Al nanoparticles into clusters by rapid heating in a shock wave has been studied. Cluster distribution characteristics were calculated as a function of the parameters of the initial nanoparticle distributions and the nature of the interaction of deformation waves with the nanoparticle shell and core. The studies were carried out using the author’s proposed resonance

Abstract Operation of shaped charges with copper hemispherical liners of degressive (decreasing from top to bottom) thickness is experimentally studied. The velocity of the head of generated shaped-charge jets is determined along with how deep they penetrate a type-setting target made of steel disks and the sizes of holes made in the disks. The experimental data on an increase in the velocity and a

Abstract The effect of friction on the critical temperature of ignition is considered by establishing the friction ignition model based on the principle of the heterogeneous reaction of Semenov. The effects of the oxygen concentration, flow velocity, friction force, and contact area on the critical temperatures of two fireproof titanium alloys (TB12 and TF550) are studied. The results show that the

Abstract Several aluminum-based explosives are prepared and their underwater explosion performances, including the specific bubble energy and specific shock wave energy, are measured in underwater explosion experiments. The formulation characteristics of the explosives involve the aluminum/oxygen (Al/O) ratio, aluminum particle size, and the total content of all solid components, including ammonium

Abstract Regimes of continuous detonation of CH4/H2–air mixtures with mass fractions of H2 in the fuel equal to 0–1/5 are obtained in an annular combustor 503 mm in diameter with variation of the combustor geometry. The influence of the combustor geometry on the velocity and number of transverse detonation waves, pressure in the combustor, and specific impulse is considered. It is found that three-fold

Abstract Insensitive munitions are munitions that are chemically stable enough to withstand thermal, mechanical, or electrical stimuli during storage and transportation, and can still explode as intended to defeat their targets. Extensive programmes have evolved worldwide for the development and introduction of insensitive munitions (IMs). The use of insensitive energetic materials significantly improves

Abstract Experimental studies of the structure of detonation waves in mixtures of tetranitromethane with methanol and nitrobenzene have been performed. Particle velocity profiles at the arrival of detonation waves at the interface with a water window were measured by a laser interferometer. It has been shown that the flow pattern in the reaction zone changes sharply at a concentration of diluents in

Abstract This paper presents the results of an experimental study of the influence of the strength of the thin-walled case of a PETN charge on the performance of small-sized pulsating explosive devices for various applications.

Abstract An improved reactive flow model with thermodynamic consistency is proposed to deal with the detonation hydrodynamics of solid explosives. Based on the assumption that the chemical mixture composed of solid-phase reactants and gas-phase products can arrive at mechanical equilibrium, but cannot arrive at thermal equilibrium, the solid-phase reactants and gas-phase products may possess one pressure

Abstract This study describes the effect of preliminary mechanical activation and SiO2 quartz content on combustion rate, maximum combustion temperature, sample elongation during combustion, compressibility of mixtures, composite particle size, phase composition, and the structural features of combustion products in a Ni–Al–SiO2 system. In Ni–Al–SiO2 initial mixtures, not subjected to mechanical activation

Abstract Formulas based on conservation laws are proposed for evaluating the conditions for combustion and detonation waves using dust or water clouds. The formulas allow the determination of the minimum concentration of dust or atomized water droplets in a cloud and the minimum length of the cloud. Specific data on the conditions for quenching methane–air mixtures typical of coal mines are given.

Abstract The flame propagation behavior and the effect of particle agglomeration are examined by changing the size of PMMA particles in laboratory-scale experiments. PMMA particles having a very narrow size distribution are used. We show that the minimum explosible concentration increases as the particle size decreases. On the other hand, the flame propagation velocity also increases as the particle

Abstract The standard enthalpies of formation of 1,1-bis(methoxy-NNO-azoxy)-3-nitro-3-azabutane and 1,1,8,8-tetrakis (methoxy-NNO-azoxy)-3,6-dinitro-3,6-diazaoctane were experimentally determined to be 87.7 \(\pm\) 3.9 and 283.8 \(\pm\) 6.2 kJ/mol, respectively. Calculations have shown that solid composite propellants containing these two compounds as gasifying components in metal-free compositions

Abstract Thanks to its mesoscopic kinetic nature, the discrete Boltzmann method has a capability of investigating unsteady detonation with essential hydrodynamic and thermodynamic nonequilibrium effects. In this work, an efficient and precise reactive discrete Boltzmann method is employed to investigate the impact of the amplitude and wave length of the initial perturbation, as well as of the chemical

Abstract Transient dynamics of formation and extinction of methane- and ethylene-fueled flames above the flat porous burner in an oxidizing atmosphere is numerically investigated. The simulated scenarios replicate the experimental conditions of the BRE (Flamenco) project of the ACME program focusing on combustion research in microgravity. The 3D unsteady model includes the multi-step and multi-component

Abstract Mathematical modeling of combustion of micron-sized and nanometer boron particles in air with allowance for changes in the heat and mass transfer mechanism and a decreasing particle size is carried out. The Knudsen number is taken as an indicator of a transition from one state to another: a continuous medium assumption is valid for describing the heat and mass transfer mechanisms in the case