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Combustion, Explosion and Shock Waves

2019 year, number 2

Investigation of the Chain Reaction of Hydrogen Oxidation by Sulfur Dioxide

A. A. Mantashyan, E. M. Makaryan, L. S. Arakelyan
Institute of Chemical Physics, National Academy of Sciences of Armenia, 374014 Erevan, Armenia
Keywords: сера, диоксид серы, цепная реакция, окисление водорода, sulfur, sulfur dioxide, chain reaction, hydrogen oxidation

Abstract >>
A non-catalytic reaction of hydrogen interaction with sulfur dioxide is studied. It is found that this reaction in fact is a chain reaction of hydrogen oxidation by sulfur dioxide resulting in the formation of elementary sulfur. A mechanism of this reaction is proposed. The reaction is studied under static conditions in the temperature interval from 350 to 500oC at a pressure of the reactingmixture with a stoichiometric composition equal to 300 torr. The numerical kinetic analysis of the mechanism is consistent with experimental data.

Reduced Kinetic Models for Methane Flame Simulations

I. Lytras, P. Koutmos, E. Dogkas
University of Patras, Patras, 26504, Greece
Keywords: сокращенная химия горения, окисление метана, ламинарные пламена, механизмы химических реакций, reduced combustion chemistry, methane oxidation, laminar flames, chemical reaction schemes

Abstract >>
The present paper describes the development of two reduced kinetic schemes suitable for multidimensional turbulent flame simulations in high-temperature oxidation of methane. Formal reduction of the USC Mech II C1-C4 detailed kinetic model by using the directed relations graph mechanism results in a 31-species derivative scheme for lean to near-stoichiometric conditions. To deduce a still shorter, simpler, and less stiff kinetic model, further species elimination is based on combined sensitivity and chemical time scale information to arrive at a 22-species scheme. The kinetic rates of lumped reactions are here expressed as simple Arrhenius rates, avoiding nonlinear algebraic combinations of excluded elementary steps or species. The accuracy is maintained by tuning pre-exponential constants in the global Arrhenius rate expressions and computing a range of target data. A more compact, quasi-global 14-species scheme is subsequently formulated by modeling fuel decomposition to a methyl radical pool, followed by CH3 oxidation with O and OH toward CH2 and CO, and retaining a full CO/H2/O2 subset. The C2-chain with recombination of CH3 into C2H6 and production of C2H2 is also represented in both schemes. Equilibrium 0D and 1D propagating premixed flames and axisymmetric co-flowing lifted laminar jet flames are computed through an iterative validation process. Accompanying computations with the USC Mech II mechanism, as well as available experimental results, are exploited for optimization. The comparisons demonstrate that the derived schemes ensure satisfactory agreement with data over the investigated parameter space.

Thermochemical and Energy Characteristics of DAzFF and AzNTF

D. B. Lempert1, A. I. Kazakov1, V. S. Sannikov2, A. V. Nabatova1, D. V. Dashko2, A. I. Stepanov2
1Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, 142432 Russia
2Tekhnolog Special Design and Technological Bureau, St. Petersburg, 193076 Russia
Keywords: 3,4-бис(4-азидофуразан-3-ил)фуроксан, 4-азидо-4''-нитро-3,3':4','3'-терфуразан, теплота сгорания, энтальпия образования, смесевое твердое ракетное топливо, удельный импульс, 3,4-bis (4-azidofurazan-3-yl) furoxan, 4-azido-4'-nitro-3,3':4','3'-terfurazan, heat of combustion, enthalpy of formation, composite solid propellant, specific impulse

Abstract >>
The heat of combustion and standard the formation enthalpy of 3,4-bis (4-azidofurazan-3-yl) furoxan (DAzFF) and 4-azido-4'$-nitro-3,3':4','3'-terfurazan (AzNTF) were experimentally determined. Thermodynamic analysis was performed to investigate the efficiency of these compounds as potential components of metal-free composite solid propellants based on an active binder with the possibility of introducing an additional small additive oxidant with a high oxygen content, such as ammonium perchlorate.

Simulation of Combustion of Solid High-Energy Materials with Account for Erosive Effects

K. O. Sabdenov, M. Erzada
North Kazakhstan State University named after M. Kozybayev, 150000 Petropavl, Kazakhstan
Keywords: поверхность газификации, внутренняя турбулентность, коэффициент эрозии, эффект Вилюнова-Дворяшина, gasification surface, internal turbulence, erosion factor, Vilynov-Dvoryashin

Abstract >>
A negative erosive effect arises in the simulation of combustion due to a generated turbulent motion in the gasification zone of a solid energy material. A thermal energy in the gasification zone comprises the heat of chemical sources in it and the heat coming up to the gasification surface from the flame zone in a gaseous phase. Some of this energy returns to the gaseous phase in the form of the mechanical energy of turbulent motion, and this turbulence cools down the gasification zone. This model is used to explain the weakening of the negative erosive effect, observed in the experiments, with increasing pressure and decreasing initial temperature.

Combustion in the Cu(NO3)2-Al(NO3)3-H2O-PVA: System: Synthesis of CuO/Al2O3

V. D. Zhuravlev, K. V. Nefedova, Sh. M. Khaliullin, I. V. Baklanova, L. Yu. Buldakova
Institute of Solid State Chemistry, Ural Branch, Russian Academy of Sciences, Ekaterinburg, 620990 Russia
Keywords: горение, синтез сжиганием растворов, нанокомпозиты, CuO/AlO, профили температуры, содержание углерода, combustion, solution burning synthesis, nanocomposites, CuO/Al2O3, temperature profiles, carbon content

Abstract >>
This paper presents the results of study of combustion processes in the Cu(NO3)2-Al(NO3)3-H2O - PVA system, the composition and characteristics of the phases formed, the influence of heat treatment conditions on phase formation and particle size of the powders. It is shown that the combustion of organic-inorganic mixtures can be used to obtain CuO/Al2O3 catalysts or precursors of CuO/Al2O3catalysts and copper-matrix composites for electrical contacts.

Dependence of the Burning Rates of Ribbons of Ti + xB Mixtures on Boron Concentration

S. G. Vadchenko
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, 142432 Russia
Keywords: скорость, пределы и механизм горения смесей титана с бором, burning rate, limits and mechanism of combustion of titanium-boron mixtures

Abstract >>
The burning rate and limits of ribbons rolled from mixtures of titanium with boron were determined as a function of the concentration of boron. The combustion of single ribbons near the lower limit is unsteady and has a two-zone structure across the width of the ribbons, due to the difference in burning and cooling rates between the edges of the ribbons and its middle. With increasing boron concentration in the mixture, the combustion becomes steady-state and the front becomes more even. Maximum burning rate of the ribbons is achieved at a boron concentration of 21-25% in the mixture.

Influencing Factors of High-Pressure Discharge Nanothermite Composites Based on Al/Bi2O3

Y.-J. Wang1, L. Guo1, Z.-S. Jiang2
1Beijing Institute of Technology, Beijing 100081, China
2Jiangnan Industry Group Co. Ltd, Xiangtan 411207, Hunan, China
Keywords: Al/BiO, нанотермит, факторы влияния, энергетические характеристики, nanothermite, influencing factor, pressure discharge property

Abstract >>
To optimize the reactant synthesis and improve the pressure property of Al/Bi2O3, the influencing factors in the dynamic pressure discharge of nanothermite reactions are investigated, including the oxide type, Bi2O3 particle size, and fuel-to-oxidant mole ratio. All samples are prepared by the ultrasonic mixing method. The synthesized Al/Bi2O3 composites are characterized by X-ray diffraction analysis and scanning electron microscopy. By using a closed bomb, the pressure discharge characteristics, including the peak pressure, ignition delay time, and pressurization rate, are obtained. Among the as-prepared nanothermites Al/CuO, Al/Fe2O3, and Al/Bi2O3, the latter shows the best pressure discharge performance. For the Al (100 nm)/Bi2O3 (47 nm) composite with an optimal stoichiometric ratio, the maximum peak pressure, the pressurization rate, and the shortest ignition delay time are 4559 kPa, 11.398 GPa/s, and 27.20 ms respectively. The results indicate that the nano-Bi2O3 particle size also produces a significant effect on the pressure output.

Formation of Grain Structure in Ni3Al Intermetallic Compound Synthesized by Thermal Explosion

V. E. Ovcharenko1,2, E. N. Boyangin1, K. O. Akimov3, K. V. Ivanov1
1Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634055 Russia
2Tomsk Polytechnic University, Tomsk 634050 Russia
3Tomsk State University, Tomsk, 634050 Russia
Keywords: тепловой взрыв, высокотемпературный синтез под давлением, интерметаллическое соединение NiAl, зеренная структура, прочность, пластичность, thermal explosion, high-temperature synthesis under pressure, intermetallic compound Ni3Al, grain structure, strength, plasticity

Abstract >>
We have studied the effect of preload and the delay in application of pressure to the product of high-temperature synthesis under conditions of thermal explosion of a powder mixture of stoichiometric composition on the grain size in the synthesized Ni3Al compound, on the nature of its fracture, strength, and ductility.

Effect of the Kinetic Scheme of Pyrolysis on Prognostic Estimates of Characteristics of Ignition of Wood Particles

G. V. Kuznetsov, S. V. Syrodoy
Tomsk Polytechnic University, Tomsk 634034 Russia
Keywords: частица древесины, воспламенение, пиролиз, кокс, летучие, кинетическая модель, время задержки зажигания, wood particle, ignition, pyrolysis, coke, volatile, kinetic model, ignition delay

Abstract >>
The effect of the kinetic model of the thermal decomposition of wood on the results of prognostic modeling of the ignition of wood particles was analyzed. The results of mathematical modeling were verified by experimental studies of the ignition of wood particles in a high-temperature environment. Comparative analysis of the delays of ignition obtained theoretically and experimentally showed their good agreement. The prognostic potential of three substantially different kinetic models of wood pyrolysis was analyzed. It was established that the model of one-step pyrolysis with the formation of gaseous reaction products provides a good description of the thermal decomposition during thermal preparation (deviation from the times obtained using the three-stage pyrolysis model does not exceed 5%) in the whole range of heating conditions. Numerical simulation results show that consideration of thermal decomposition reactions of the second and third levels with the formation of intermediate pyrolysis products (liquid and solid) does not have a significant influence on the characteristics and conditions of ignition of wood particles in a high-temperature gas environment.

Experimental Investigation on the Ignition and Combustion Characteristics of a Single Magnesium Particle in Air

Y.-Ch. Feng, Zh.-X. Xia, L.-Y. Huang, L.-K. Ma, D.-L. Yang
National University of Defense Technology, Changsha, 410073 China
Keywords: частица магния, горение частицы магния, температура зажигания, пламя, область тепловыделения, воздух, single magnesium particle, magnesium particle combustion, ignition temperature, flame, heat release region, air

Abstract >>
In this study, millimeter-sized magnesium particles are ignited using a CO2 laser. The flame structure, particle temperature, heat release region, and spectral information of the burning magnesium particle are determined. The experimental results show that the developing process of the particle temperature can be divided into five stages: gradually rising stage, steady stage, sharply rising stage, high-temperature stage, and descent stage. Through a series of ignition experiments, the ignition temperature of a magnesium particle ≈3 mm in air is estimated to be 900-940 K. During steady combustion, the maximum diameters of the flame and of the heat release region are found to be greater than the particle diameter approximately by a factor of 1.9 and 3-3.5, respectively. The experimental results also suggest that the combustion of magnesium in air should be controlled by vapor diffusion from the particle surface.

Dielectric Relaxation in Energy Condensed systems on the Basis of a Polyesterrethane Elastomer. II. Temperature Dependence and Ignition

D. N. Sadovnichii1, Yu. M. Milyokhin1, S. A. Lopatkin2, T. S. Skripina2, S. A. Malinin1, I. N. Gross1
1The Federal Center for Dual-Use Technologies "Soyuz", Dzerzhinsky, 140090 Russia
2National Research Tomsk Polytechnic University, Tomsk, 634050 Russia
Keywords: энергетические конденсированные системы, воспламенение, тринитрат глицерина, перхлорат аммония, октоген, диэлектрическая релаксация, комплексная диэлектрическая проницаемость, тепловой пробой, energy condensed systems, ignition, glycerol trinitrate, ammonium perchlorate, HMX, dielectric relaxation, complex dielectric permeability, thermal breakdown

Abstract >>
This paper describes the effect of the composition of energy condensed systems, containing glycerol trinitrate, aluminum powder, ammonium perchlorate, and HMX, on their ignition in an electric field with a frequency of 50 Hz. Conditions under which energy condensed systems ignite in an alternating electric field with a frequency of 50 Hz are determined experimentally. Temperature changes of their dielectric characteristics in a frequency range from 20 Hz to 1 MHz are established. The possibilities of an electric breakdown and heating of the samples are theoretically estimated. It is revealed that electrical luminescence is observed in a polymer binder based on glycerol trinitrate and polyetherurethane.

Effect of Inert Microand Nanoparticles on the Parameters of Detonation Waves in Silane/Hydrogen-Air Mixtures

D. A. Tropin, A. V. Fedorov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: подавление детонации, композитные смеси силан/водород, детальная химическая кинетика, математическое моделирование, газовзвесь, наночастицы, detonation suppression, silane/hydrogen composite mixtures, detailed chemical kinetics, mathematical modeling, gas suspension, nanoparticles

Abstract >>
Physicomathematical modeling of interaction of detonation waves in silane/hydrogen composite mixtures with clouds of inert micro- and nanoparticles ranging from 10 nm to 100 μm is performed. The normalized detonation velocity is calculated as a function of the volume concentration of particles. It is found that the efficiency of detonation suppression increases only as the particle diameter decreases to 1 μm. The influence of the thermodynamic parameters of particles on the detonation suppression efficiency is identified. The concentration limits of detonation are determined. It is demonstrated that a certain equilibrium asymptotic level of the concentration limits of detonation is reached as the particle diameter decreases below 1 μm. An approximation of the concentration limits of detonation is obtained in the form of an analytical dependence of the limiting volume concentration of particles on their diameter and fuel concentration in a composite two-fuel mixture of silane, hydrogen, and air.

Laser Initiation of PETN with Inclusions of Aluminum Nanoparticles under Static Pressure

B. P. Aduev, D. R. Nurmukhametov, G. M. Belokurov, A. A. Zvekov, N. V. Nelyubina
Institute of Coal Chemistry and Material Science, Federal Research Center of Coal and Coal Chemistry, Siberian Branch, Russian Academy of Sciences, Kemerovo, 650000 Russia
Keywords: лазерное инициирование, тэн, взрыв, газодинамическая разгрузка, дислокации, наночастицы алюминия, оптоакустика, laser initiation, PETN, explosion, gas-dynamic unload, dislocation, aluminum nanoparticles, optoacoustics

Abstract >>
This paper describes the experimental measurement of thresholds of explosive decomposition of PETN with inclusions of aluminum nanoparticles (an average particle diameter of 100 nm) with a static pressure of 0-0.288 GPa applied to the samples under the action of the first harmonic of pulsed (14 ns) neodymium laser. Amplitudes of optoacoustic signals as a function of concentration of inclusions in the samples with a fixed density of laser initiation energy are measured. There is a significant decrease in the initiation threshold, which is due to the fact that a gas-dynamic load is blocked and the sample density increases.