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Combustion, Explosion and Shock Waves

2017 year, number 4

New Directions in the Area of Modern Energetic Polymers: an Overview

D. M. Badgujar1, M. B. Talawar2, V.E. Zarko3, P. P. Mahulikar1
1North Maharashtra University, Jalgaon, 425001, India
2High Energy Materials Research Laboratory, Pune, 411021, India
3Voevodsky Institute of Chemical Kinetics and Combustion, Novosibirsk 630090, Russia
Keywords: энергетические полимеры, термопластичные эластомеры, энергетические связующие, взрывчатые вещества с полимерным связующим (PBX), энергетические пластификаторы, карборановые полимеры, энергетические полифосфазены, energetic polymers, thermoplastic elastomers, energetic binders, plastic bonded explosives (PBX), energetic plasticizers, carborane polymers, energetic polyphosphazenes

Abstract >>
Energetic polymers containing nitro, nitrato, and azido groups release high energy during combustion and thereby increase the performance of the systems. A number of energetic polymers have been found suitable for use as binders in high-performance propellant and explosive formulations. This review describes the synthetic aspects and applications of various modern energetic polymers for explosive formulations and propellants.

Experimental and Numerical Investigation of the Chemical Reaction Kinetics in Syngas H2/CO Flame at a Pressure of 1-10 atm

D. A. Knyaz'kov1,2, T. A. Bolshova1, A. M. Dmitriev1,3, A. G. Shmakov1,3, O. P. Korobeinichev1
1Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Far Eastern Federal University, Vladivostok, 690950 Russia
3Novosibirsk State University, Novosibirsk 630090 Russia
Keywords: синтез-газ, молекулярно-пучковая масс-спектрометрия, пламя предварительно перемешанной смеси, численное моделирование, высокое давление, syngas, molecular beam mass spectrometry, premixed flame, numerical simulation, high pressure

Abstract >>
The structure of a premixed flame of syngas (H2/CO/O2/Ar = 0.0667/0.0667/0.0667/0.8) of stoichiometric composition stabilized on a flat burner at a pressure of 5 atm was studied experimentally and by numerical simulation. The chemical-kinetic mechanisms for the oxidation of a H2/CO mixture proposed in the literature. Good agreement was found between the results of the experiment and simulation. Calculations of the flame structure of the same composition at a pressure of 1 and 10 atm were performed to establish the effect of the pressure on the chemical reaction kinetics in the syngas flame. The results were explained by kinetic analysis of the mechanisms.

Numerical and Experimental Study of Ignition of a Two-Phase Fuel Composition (Air + Ethanol) in a Resonance Gas-Dynamic System

K. Yu. Aref'ev1,2, A. V. Voronetskii2, M. A. Il'chenko1, S. A. Suchkov2
1Baranov Central Institute of Aviation Motors, Moscow, 111116 Russia
2Bauman Moscow State Technical University, Moscow, 105005 Russia
Keywords: двухфазное течение, газодинамическое воспламенение, дробление капель, испарение капель, резонансная газодинамическая система, two-phase flow, gas-dynamic ignition, droplet fragmentation, droplet evaporation, resonance gas-dynamic system

Abstract >>
A mathematical model, laboratory setup description, and results of a numerical-experimental study of specific features of an unsteady two-phase flow of the air-ethanol fuel composition in the duct of a resonance gas-dynamic system (RGS) are presented. The basic specific features of ignition of the fuel mixture in the resonance cavity are detected. The conditions of ignition are determined, and the ignition delay time of the fuel composition in the RGS is estimated. The data obtained in this study can be used for modeling physical and chemical processes and for choosing liquid fuel injection modes satisfying the conditions of ignition of two-phase fuel mixtures in the RGS.

Chemical Reactor Network Application to Predict the Emission of Nitrogen Oxides in an Industrial Combustion Chamber

T. H. Nguyen
Nong Lam University of Ho Chi Minh City, Viet Nam Ward 6, Linh Trung, Thu Duc, Ho Chi Minh City, Viet Nam
Keywords: промышленная камера сгорания, сжиженный природный газ, зонная модель, оксиды азота, industrial combustion chamber, LPG, chemical reactor network, nitrogen oxides

Abstract >>
A new chemical reactor network model is developed to predict the emission of nitrogen oxides in an industrial combustion chamber operating on liquefied petroleum gas. The boundary conditions and operating parameters used for this model are typical operating conditions of an industrial combustion chamber. The global mechanism is developed by GRI-MECH 3.0 in the UW code. The model predictions are compared with experimental data. The chemical reactor network model provides an accurate estimation of nitrogen oxide emission.

Simulation of the Solid-Phase Reaction Distribution in the Case of Conjugate Heat Exchange

K. A. Aligozhina1,2, A. G. Knyazeva1,2,3
1Tomsk Polytechnic University, Tomsk, 634050 Russia
2Institute of Strength Physics and Materials Science, Siberian Branch, Russian Academy of Sciences, Tomsk, 634021 Russia
3Tomsk State University, Tomsk, 634050 Russia
Keywords: твердофазная реакция, сопряженный теплообмен, режимы превращения, распределение температуры, solid-phase reaction, conjugate heat exchange, transformation regimes, temperature distribution

Abstract >>
This paper describes the model of the propagation of solid-phase exothermic reaction in a layer between inert materials with various thermal and physical properties. The model is implemented numerically. The relationships between the ignition time and the model parameters, as well as the behavior of some energy characteristics under various conditions in time (heat reserve in the heated layer and excess of enthalpy). The influence of the thermal and physical properties of inert materials on the temperature distribution in the sample in stationary and nonstationary regimes is demonstrated.

Estimating the Self-Diffusion Coefficients and Mutual Diffusion of Binary Mixtures on the Basis of Modified Van der Waals Model

A. B. Medvedev1,2,3
1RFNC, All-Russian Research Institute of Experimental Physics, Sarov, 607188 Russia
2Sarov Institute of Physics and Technology, Sarov, 607186 Russia
3National Research Nuclear University, Moscow, 115409 Russia
Keywords: жидкость, газ, бинарная смесь, коэффициент диффузии, давление, температура, плотность, концентрация, уравнение состояния Ван-дер-Ваальса, liquid, gas, binary mixture, diffusion coefficient, pressure, temperature, density, concentration, Van der Waals state equation

Abstract >>
On the basis of the previously proposed model, the values of the self-diffusion coefficient of He, Ne, Ar, Kr, Xe, H2, D2, N2, O2, CO2, NH3, and CH4 The previously proposed model is used to determine the values of the coefficient self-diffusion He, Ne, Ar, Kr, Xe, H2, D2, N2, O2, CO2, NH3, and CH4 in the liquid and dense gaseous states, which were compared with the experimental data obtained at a pressure ≈200 MPa and a temperature ≈500 K. The calculations are carried out with the use of the state equation of these substances in the form of a modified Van der Waals model. The self-diffusion model was generalized for the case of mutual diffusion in binary mixtures, which is based on the modified model of the Van der Waals state equation for mixtures. The model coefficient of mutual diffusion for a great number of binary mixtures of the above-mentioned individual substances is determined, and the results are compared with the known data. Without special calibration for the experiment, the model correctly predicts the relationship of the self-diffusion and mutual diffusion coefficients (with their change by several orders of magnitude in the case where the density changes from gaseous to liquid) with both pressure and temperature. For most substances considered in the paper, the maximum deviations of calculations from the experiment do not exceed 30-50%.

Mathematical Modeling of Propagation of Explosion Waves and Their Effect on Various Objects

S. A. Valger1,2, N. N. Fedorova1,2, A. V. Fedorov1,2
1Novosibirsk State University of Architecture and Civil Engineering, Novosibirsk, 630008 Russia
2Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: взрыв, ударно-волновые воздействия, программные комплексы, ANSYS, AUTODYN, explosion, shock wave action, software packages

Abstract >>
Results of modeling propagation of a shock wave formed by an explosion of a spherical charge of a high explosive in a semi-infinite space bounded by a plane substrate are reported. Problems of the action of such a wave on objects rigidly fixed on the substrate (single prism and a set of prisms simulating an urban area) are considered. The computations are performed in a three-dimensional inviscid formulation with the use of the AUTODYN module of the commercial software package ANSYS. These numerical predictions are compared with experimental data on the static pressure in sensors mounted on the prism walls. A possibility of providing an adequate description of the unsteady flow pattern formed around the obstacles mounted on the substrate is demonstrated. Based on these numerical data, the intensity of the shock wave action on various objects is estimated.

Role of Particle Collisions in Shock Wave Interaction with a Dense Spherical Layer of a Gas Suspension

T. A. Khmel', A. V. Fedorov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: газовзвеси, ударные волны, диспергирование, столкновительная динамика, gas suspensions, shock waves, dispersion, collision dynamics

Abstract >>
The problem of interaction of an expanding spherical shock wave with a layer of particles is considered within the framework of the model of mechanics of continuous media with due allowance for granular pressure in the dense gas suspensions. The influence of particle collisions on the shock wave expansion process is analyzed. Generation of collision pressure and formation of shock wave structures in the gas suspension are found to be the governing factors of motion of the cloud of particles at the initial stage.

Detonation Combustion of Lignite with Titanium Dioxide and Water Additives in Air

F. A. Bykovskii1, E. F. Vedernikov1, Yu. A. Zholobov2
1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
2Novosibirsk State University, Novosibirsk, 630090 Russia
Keywords: непрерывная спиновая детонация, пульсирующая детонация, радиальная вихревая камера сгорания, бурый уголь, шлам, синтез-газ, continuous spin detonation, pulsed detonation, radial vortex combustor, lignite, slurry, syngas

Abstract >>
The influence of mineral additives (6.2-70% and water (15-54% to lignite on the possibility of its burning in an air flow in a continuous detonation regime in a radial vortex combustor 500 mm in diameter is studied. A syngas with a composition CO + 3H2 is used for transporting the coal mixture and for promoting the chemical reaction. It is shown that regimes of continuous spin detonation, conventional combustion, and pulsed combustion may occur depending on the amounts of the mineral (TiO2) added to coal, water, and syngas. The boundaries between the domains of existence of detonation and combustion are determined in the coordinates of the ratio of the syngas flow rate to the rate of consumption of the combustible portion of coal and the mineral component of coal and water. It is seen that the continuous spin detonation regime persists if the mineral additive fraction in the lignite mixture is up to 65% and the water fraction is smaller than 30%. It is also demonstrated that the syngas flow rate should be increased with increasing mineral additive fraction and increasing coal humidity in order to ensure burning of the combustible component of syngas.

Detonation Velocity of Mechanically Activated Mixtures of Ammonium Perchlorate and Aluminum

A. A. Shevchenko1,2,3, A. Yu. Dolgoborodov1,2,3, V. G. Kirilenko1, M. A. Brazhnikov1
1Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow, 119991 Russia
2Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 119991Russia
3MEPhI National Research Nuclear University, Moscow, 115409 Russia
Keywords: перхлорат аммония, алюминий, наноалюминий, механоактивация, псевдоидеальная детонация, ammonium perchlorate, aluminum, nanosized aluminum, mechanical activation, pseudo-ideal detonation

Abstract >>
The detonation properties of mechanically activated mixtures of ammonium perchlorate and aluminum were studied. The transition from combustion of low-density charges to detonation was investigated. Dependences of the detonation velocity of compacted charges with various types of aluminum on the activation time, the charge density and diameter were obtained. For compositions with nanosized aluminum, the detonation velocity was found to depend nonmonotonically on the reverse charge diameter, remaining almost unchanged in a certain range of charge diameters. It is shown that the joint use of mechanical activation and nanosized components of the composite explosive significantly increases the detonation capacity, reduces the critical diameter, and shifts the maximum on the detonation velocity vs. density curve to the highest charge densities.

Numerous Experiment on Impact Compression of the Mixture of Graphite with Water

L. V. Shurshalov1, A. A. Charakhchtyan1, K. V. Khishchenko2
1Dorodnicyn Computing Centre, Russian Academy of Sciences, Moscow, 119333 Russia
2Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia
Keywords: искусственные алмазы, математическое моделирование, графитовые частицы, смесь графита с водой, artificial diamonds, mathematical modeling, graphite particles, mixture of graphite and water

Abstract >>
This paper describes the problem of the behavior of a mixture of small graphite particles with water in the conditions of shock-wave action at a pressure of 32 GPa and a temperature of up to 1200-1600 K. Graphite particles at these pressures and temperatures are capable of transforming into cubic diamonds or at least into their hexagonal form that is lonsdaleite. It is shown that, for sufficiently small graphite particles of the order of 1 m, their mixture with water for about 10  m can heat up to the above-mentioned temperatures and undergo phase transformation, remain in those conditions for about 50 ms, and then efficiently cool down during the next 50s to the temperatures below 300 K, while remaining in the diamond phase.

Formation of a Flow of High-Velocity Particles by Shaped Charges with a Liner Consisting of a Hemisphere and a Degressive-Thickness Cylinder

S. V. Fedorov1, S. V. Ladov1, Ya. M. Nikol'skaya1, V. D. Baskakov1, M. A. Baburin1, A. E. Kurepin2, A. A. Gorbunkov3, A. S. Pirozerskii4
1Bauman Moscow State Technical University, Moscow, 105005 Russia
2Bakhirev GosNIIMash, Dzerzhinsk, 606002 Russia
3Geodeziya Research Institute, Krasnoarmeisk 141292 Russia
4Bazalt, Moscow, 105058 Russia
Keywords: взрывное метание, кумулятивный заряд, комбинированная облицовка полусфера - цилиндр, дегрессивная толщина, высокоскоростной элемент, explosive throwing, shaped charge, combined liner consisting of a hemisphere and a degressive-thickness cylinder, high-velocity element

Abstract >>
X-ray diffraction of particle fluxes formed by shaped charges with a combined steel liner consisting of a hemisphere and a cylinder with a hemispherical part of degressive thickness (decreasing from top to bottom). It has been found experimentally that the transition from a constant to a degressive thickness of the hemispherical part increases the velocity of the head portion of the jet flow of the liner material formed during its compression, which is subsequently cut off during collapse of the cylindrical part. The maximum velocity of the particles obtained as a result of <cutoffs> in experiments was 8.6 km/s.

Penetration of Two-LayerTargets with an OuterCeramic Layer and Optimization of Their Structure

I. F. Kobylkin
Bauman Moscow State Technical University, Moscow, 105005 Russia
Keywords: пробивание, двухслойные преграды, керамика, органопластик, предельная скорость пробития, оптимизация, penetration, two-layered targets, ceramics, organoplastic, limiting penetration velocity, optimization

Abstract >>
Analytical formulas are obtained for calculating the limiting penetration velocity of two-layer cermet and ceramic-organoplastic targets that take into account the structural characteristics of the target and the physical and mechanical properties of the impactor and target materials. Using these formulas, the ballistic stability of targets were studied, and the possibility of optimizing their structure was shown. Received the results agree qualitatively with available experimental data. The optimal relative thickness of the ceramic layer which provides the maximum penetration velocity was determined in the range of the surface density of the target 30-50 kg/m2 for different substrate materials. It turned out that these velocity values depend weakly on the surface density of the target and are mainly determined by the properties of the substrate material.