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Combustion, Explosion and Shock Waves

2019 year, number 1

Problems of Closing Models that Describe Detonation of Gas Suspensions of Ultrafine Aluminum Particles (Review)

A. V. Fedorov, T. A. Khmel
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: детонация, газовзвесь, алюминий, микрочастица, наночастица, математическое моделирование, detonation, gas suspension, aluminum, microparticle, nanoparticle, mathematical modeling

Abstract >>
Various publications dealing with physicomathematical modeling of detonation processes in gas suspensions of fine, submicron, and nano-sized aluminum particles within the framework of mechanics of continuous and heterogeneous media are reviewed. Important issues of the description of thermal dynamics, transport properties, and ignition mechanisms are discussed. Specific features of combustion regimes of micro- and nano-sized particles are considered. Closing relations for a semi-empirical model of detonation of suspensions of aluminum nanoparticles in oxygen are presented.

Observation of Free Induction Signals of Radicals Excited by Terahertz Free-Electron Laser Pulses

E. N. Chesnokov1, L. N. Krasnoperov2, V. V. Kubarev3, P. V. Koshlyakov1
1Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Technological University of New Jersey, NJ 07102, Newark, U.S
3Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: радикал ОН, свободная индукция, терагерцовое излучение, OH radical, free induction, terahertz radiation

Abstract >>
The first experimental observation of optical free induction signals of free radicals is reported. The signals were observed on the line of the rotational transition of the OH radical in the terahertz region. OH radicals were generated in the chemical reaction of excited oxygen atoms with water molecules. Radicals were excited by free-electron laser radiation pulses. Free induction radiation was detected in real time using ultra fast terahertz radiation detectors. The possibility of using optical free induction signals of radicals as a new method for detection of free radicals in combustion processes is discussed.

Thermochemical and Energy Characteristics Di-, Tri-, and Tetraazide-Substituted Azines as Gas-Forming Components of Solid Propellants for Ramjet Engines

D. B. Lempert, S. V. Chapyshev, A. I. Kazakov, N. A. Plishkin, A. V. Shikhovtsev, L. S. Yanovskii
Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: азиды, тетразины, триазины, пиримидины, пиридины, энергетические материалы, теплота сгорания, энтальпия образования, твердое ракетное топливо, azides, tetrazines, triazines, pyrimidines, pyridines, energetic materials, heat of combustion, enthalpy of formation, solid rocket propellant

Abstract >>
A number of di-, tri-, and tetraazido-substituted azines as potential energetic dispersing components of solid rocket propellants for ramjet engines have been studied. The enthalpy of combustion and the enthalpy of formation of several azides (2,4,6-triazidopyrimidine, 2,4,6-triazidopyridine, 3,4,5-triazidopyridine-2,6-dicarbonitrile and 3,4,5,6-tetraazidopyridine-2-carbonitrile) were experimentally determined. Eleven azides studied were compared with MX in terms of the enthalpy of combustion in oxygen to CO2 and water (in the case of the presence of hydrogen in the component), as well as in terms of the temperature of the products of adiabatic conversion of the studied components due to the high enthalpy of formation in the absence of an external oxidizer and the amount of gases released in this process. It has been found that the enthalpy of combustion of all the investigated azides burned in air is significantly higher than that of HMX, and in seven of the azides studied, the combustion temperature was significantly higher. As regards the gas release volume (24-31 mol/kg), the azides are inferior to HMX (41.9 mol/kg). Based on the combination of properties, the investigated azides can be considered as promising dispersing components of solid propellants for ramjet engines.

Energetic Potential of Some Hypothetical Derivatives of Tetrazole as Components of Composite Rocket Fuel

I. Yu. Gudkov, V. P. Kosilko, D. B. Lempert
Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: производные тетразола, ракетное топливо, удельный импульс, окислитель, связующее, tetrazole derivatives, rocket propellant, specific impulse, oxidizer, binder

Abstract >>
Thermochemical calculations have been used to study the energetic potential of compositions based on a number of hypothetical tetrazole derivatives with a very high mass content of nitrogen (73-75%). Quantitative dependences of the energy parameters of composite solid rocket fuels on the nature of a high-enthalpy polynitrous oxidizer and the presence of a metal in the composition have been established.

Combustion of Spherical Titanium Aglomerates in Air. III. Movement of Agglomerates and the Effect of Airflow Velocity on Nanosized Combustion Products and Burning Time

O. G. Glotov, G. S. Surodin, A. M. Baklanov
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: частица титана, титановый агломерат, горение, скорость движения частицы, характерное время фрагментации, время горения, конденсированные продукты горения, наноразмерные оксидные частицы-сферулы, распределение по размерам, titanium particle, titanium agglomerate, combustion, particle velocity, characteristic time of fragmentation, burning time, condensed combustion products, nanosized oxide spherule particles, size distribution

Abstract >>
The combustion of monodisperse titanium particles with a characteristic size of 38 and 320 m moving in air has been studied. Pyrotechnic samples generating monodisperse particles were burned in a chamber with a nozzle to impart initial velocity to burning particles. Particles were accelerated by the combustion gas flow from the nozzle. The maximum path-averaged particle velocity relative to the ambient air reached 7.9 m/s. Combustion of moving particles was carried out in a quartz tube 2 m long. At the end of the combustion, combustion products - oxide aerosol - were sampled from the tube using a thermophoretic precipitator. The size distribution function of nanometer-sized spherule particles was determined by processing electron micrographs of samples. The velocity and burning time of the burning particles were determined by video recording at a velocity of 300 frame/s. It was found that increasing the speed of motion of agglomerate particles with a diameter of 320 m relative to the gas from 0.9 to 7.9 m/s leads to a decrease in the size of the spherules from 28 to 19 nm and to a decrease in the burning time from 0.45 to 0.26 s.

Efficiency of Combustion of Boron-Containing Particles of the Condensed Phase in Channels with Distributed Injection of Air

K. Yu. Aref'ev1,2, L. S. Yanovskii1,3
1Baranov Central Institute of Aviation Motors, Moscow, 111116 Russia
2Bauman Moscow State Technical University, Moscow, 105005 Russia
3Institute for Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: двухфазное течение, коэффициент полноты сгорания, математическое моделирование, распределенный подвод воздуха, канал постоянного сечения


Mathematical Modeling of Premixed Counterflow Combustion of a Submicron-Sized Aluminum Dust Cloud

H. Khalili1, S. A. Madani1, M. Mohammadi2, A. K. Poorfar1, M. Bidabadi1, P. Pendleton3
1Iran University of Science and Technology, Narmak, Tehran, 16846-13114 Iran
2Institute of Geophysics, Warsaw, 02093 Poland
3University of Adelaide, Adelaide, SA 5000 Australia
Keywords: термофорез, броуновское движение, частицы алюминиевой пудры, структура пламени, асимптотическое решение, thermophoresis effect, Brownian motion, aluminum dust particles, flame structure, asymptotic solution


Electrothermal Explosion of a Titanium - Soot Mixture under Quasistatic Compression. I. Thermal and Electric Parameters

V. A. Shcherbakov, A. V. Shcherbakov, S. A. Bostandzhiyan
Erzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: электротепловой взрыв, кинетика высокотемпературного взаимодействия, карбид титана, electrothermal explosion, high-temperature interaction kinetics, titanium carbide

Abstract >>
The study of an electrothermal explosion (ETE) of a titanium - soot mixture under quasistatic compression is described. Experimental dependences of thermal and electric parameters of the ETE on the power of electric heating are obtained. It is shown that the heating rate of a reacting mixture significantly affects the ignition temperature and maximum temperature of the ETE. It is determined that, at the stage of pre-explosion heating, the electric resistance of the mixture decreases by 90-95%, and the rate of the temperature rise during a thermal explosion is independent of the heating rate of the mixture. A technique for determining the ignition time and temperature, based on measuring the thermal and electric parameters of the ETE. Liquid-phase and solid-phase interactions in the titanium - soot mixture powders are discussed.

Electrothermal Explosion of a Titanium - Soot Mixture under Quasistatic Compression. II. KInetics and Mechanism of Interaction in a Titanium - Soot Mixture

V. A. Shcherbakov, A. V. Shcherbakov, S. A. Bostandzhiyan
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: электротепловой взрыв, высокотемпературная кинетика, карбид титана, electrothermal explosion, high-temperature kinetics, titanium carbide

Abstract >>
The experimental study of the high-temperature interaction kinetics of a titanium - soot mixture under quasistatic compression in an electrothermal explosion (ETE) is described. Dependences of the heating rate of a sample mixture on temperature are obtained, and the effective values of the energy of ignition activation and thermal explosion are calculated. The formation of the microstructure of intermediate and final interaction products is investigated. It is shown that the formation of a final product occurs according to a shell - core mechanism. The high rate of the solid-phase interaction of titanium and soot is explained by the formation of micropores and microcracks in the intermediate product, which ensure the high rate of surface diffusion of carbon.

Thermocapillary Convection in a Gas-Free Combustion Wave

V. G. Prokofiev1,2, V. G. Smolyakov1,2
1Tomsk State University, Tomsk, 634050 Russia
2Tomsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Tomsk, 634021 Russia
Keywords: плавление реагента, термокапиллярная конвекция, кондуктивный и конвективный режимы горения, приближенный анализ, численное моделирование, melting reagent, thermocapillary convection, conductive and convective combustion regimes, approximate analysis, numerical simulation

Abstract >>
The effect of thermocapillary convection on heat transfer in a gas-free combustion wave with a melting reagent is studied analytically and numerically. Convection rate estimates are given. Equations for a burning rate in conductive and convective heat transfer are obtained. Numerical calculations confirm the conclusions of an analytical analysis. Calculated dependences of the burning rate on porosity and phase transition parameters are obtained. The development of instability of a combustion wave propagation in self-oscillating regimes, caused by the action of thermocapically convection, is revealed.

Effect of High-Energy Milling on Magnesiothermic Self-Propagating High-Temperature Synthesis in a Mixture of SiO2, C, and Mg Reactant Powders

T. Chanadee1,2, S. Singsarothai3
1Prince of Songkla University, Hat Yai, Songkhla, 90110, Thailand
2Center of Excellence in Materials Engineering, Hat Yai, Songkhla, 90110 Thailand
3Thaksin University, Papayom, Pattalung, 93210, Thailand
Keywords: магнийтермическое восстановление, самораспространяющийся высокотемпературный синтез, композит Si, SiC, высокоэнергетическая механическая обработка, magnesiothermic reduction, self-propagating high-temperature synthesis, Si-SiC composite, high-energy milling

Abstract >>
A mixture of SiO2, C, and Mg powders is mechanically milled in a planetary ball mill during different milling times of 60, 90, 120, and 150 min. The milled powders are then used in a self-propagating high-temperature synthesis (SHS) reaction to produce the Si-SiC composite. The thermal properties of the milled powders are determined by using differential scanning calorimetry and thermogravimetry. The chemical composition and microstructure of both as-synthesized products and as-leached powders are characterized by the x-ray diffraction analysis and scanning electron microscopy, respectively. The results show that an increase in the milling times of the mixture of the reactant powders has a significant effect on the thermal properties, diffusion processes, and SHS reaction mechanisms, as well as on the phase conversion and the final yield of the products.

Mathemathical Simulation of the Combustion of a Mechanically Activated 3Ni + Al Mixture

O. V. Lapshin, V. K. Smolyakov
Tomsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
Keywords: порошковая смесь, механическая активация, волна горения, powder mixture, mechanical activation, combustion wave

Abstract >>
A mathematical model of synthesis in a mechanically activated 3Ni-Al is constructed in a macroscopic approximation. Different combustion regimes as a function of duration of mechanical activation and the time of the isothermal exposure of the mechanical mixture are determined. Experimental data are used to calculate kinetic constants that characterize the transformation of the substance at the stage of mechanical treatment.

Detonation of Low-Density Explosives

A. P. Ershov, I. A. Rubtsov
Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: детонация, взрыв, модель ЗНД, взрывное горение, detonation, explosion, ZND model, explosive combustion

Abstract >>
Electromagnetic measurements of the particle velocity are performed in a situation when the detonation wave reaches the interface between a high explosive (HE) powder and a window made of an inert material (Plexiglas). PETN, RDX, and HMX with densities close to the natural bulk density are studied. As it is necessary to measure not only the averaged velocity profile, but also possible fluctuations at scales of the order of the HE grain size, a method of measurements by small sensors with the working arm length approximately 1 mm is developed and tested. In most experiments, profiles with clear chemical spikes are obtained; in some of the measured results, however, the chemical spike cannot be identified on the background of sharp signal oscillations, which may be considered as manifestation of the nonclassical mechanism of wave propagation (explosive combustion in Apin's classification). As compared with the previous study, the present results suggest parallel operation of the shock and convective mechanisms with domination of each mechanism at certain segments of the wave front.

On the Effect of Combustion Inhibitors on the Level of Non-Equilibrium Radiation during Ignition of Hydrogen Oxygen Mixtures behind a Shock Wave

A. V. Eremin1, M. R. Korshunova1,2, E. Yu. Mikheeva1,2
1Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia
2Bauman Moscow State Technical University, Moscow, 105005 Russia
Keywords: воспламенение водорода, ингибирование, взрывобезопасность, неравновесное излучение, hydrogen ignition, inhibition, explosion safety, non-equilibrium radiation

Abstract >>
The nonequilibrium radiation arising from the ignition of a 10 % stoichiometric hydrogen-oxygen mixture doped with combustion inhibitors and diluted with argon behind shock waves was studied. The addition of halogen-containing inhibitors led to increased UV radiation around the 220 and 411 nm wavelengths characteristic of the HO2 radical and H2O2 and H2O molecules, instead of the expected reduction in the super-equilibrium radiation of active radicals in the ignition zone. Therefore, the hypothesis about the inhibition mechanism due to extinguishing by the excited HO2* radical is not confirmed, and the effect of inhibiting additives is due to the binding of H and O atoms.