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Vol 55, No 4 (2019)

Article

Is It Possible to Determine Normal Burning Parameters from the Detonation Theory?

Vasil’ev A.A.

Abstract

Within the framework of the classical one-dimensional theory of detonation based on conservation laws, the lower branch of the adiabat of energy release of the combustible mixture as a geometric place of the points of the final state of the system admits a solution for combustion waves whose propagation velocity Dfl ranges from zero to the deflagration velocity: 0 ⩽ DflDdef. The normal burning wave propagation velocity Su is located in this interval (0 ⩽ SuDdef), but it is traditionally calculated with the use of the thermal theory of combustion rather than detonation theory. Various approaches to choosing the final state point on the lower branch of the energy release adiabat for normal burning are analyzed in the present paper. Estimates are provided both for the degree of correspondence of the predicted and experimental velocities of flame propagation and for the degree of correspondence of the qualitative behavior of these dependences on the basis parameters of the mixture. For most hydrocarbon fuels considered in the study, the best agreement with the experimental data on Su is provided by the formula defining the flame velocity Dfl as the mean geometric value between the diffusion velocity Sdiff and deflagration velocity Ddef.

Combustion, Explosion, and Shock Waves. 2019;55(4):373-383
pages 373-383 views

Modeling of an Irregular Cellular Structure of the Detonation Wave in a Two-Fuel Mixture

Trotsyuk A.V., Fomin P.A.

Abstract

A two-stage reduced model of chemical kinetics of detonation combustion of a mixture of two fuels, i.e., hydrogen and carbon oxide (syngas), with an oxidizer is proposed. Based on this model, a two-dimensional numerical simulation of the parameters of an irregular cellular structure of the detonation wave in the considered binary mixture of two fuels with an oxidizer is performed.

Combustion, Explosion, and Shock Waves. 2019;55(4):384-389
pages 384-389 views

Generation of Large-Scale High-Velocity Vortex Rings by Initiating an Explosive

Akhmetov D.G., Kotelnikova M.S., Nikulin V.V., Plastinin A.V., Chashnikov E.A., Kop’ev V.F., Zaitsev M.Y.

Abstract

By initiating explosive charges in a cylindrical tube with one end face being plugged, vortex rings with diameters of the order of 1 m and initial velocity of motion greater than 100 m/s are obtained. Such rings emit a clearly heard acoustic signal, which is of interest for studying generation of acoustic waves by vortices and scaling mechanisms of noise generation. Vortex rings are generated due to exhaustion of a high-velocity gas jet formed after shock wave propagation over the tube. The measured vortex velocities are found to be weakly dependent on the explosive mass, i.e., as the mass increases, the fraction of energy transformed to the vortex ring energy becomes smaller.

Combustion, Explosion, and Shock Waves. 2019;55(4):390-394
pages 390-394 views

Critical Conditions of Spark Ignition of a Bidisperse Aluminum Powder in Air

Moiseeva K.M., Krainov A.Y., Dement’ev A.A.

Abstract

This paper presents a physicomathematical model and the results of numerical solution of the spark ignition problem for a suspension of a bidisperse aluminum powder in air. The critical ignition conditions of the aluminum-air suspension were determined numerically as a function of the particle size and mass concentration and the content of large and small particles in the suspension. The study has shown the effect of the fine particle fraction in the bidisperse aluminum powder on the critical spark ignition conditions of the aluminum-air suspension with the subsequent establishment of a steady regime of combustion front propagation.

Combustion, Explosion, and Shock Waves. 2019;55(4):395-401
pages 395-401 views

New Nanocarbon High-Energy Materials

Mansurov Z.A., Atamanov M.K., Elemesova Z., Lesbaev B.T., Chikradze M.N.

Abstract

The differential thermal analysis is applied to study the influence of activated carbon with multilayer graphenes (three and more sheets) on the thermal decomposition of a substance based on hydroxylammonium nitrate and carboxyl methyl cellulose. It is demonstrated that addition of activated carbon with multilayer graphenes lead to an increase in the burning rate of hydroxylammonium nitrate up to four times. Addition of activated carbon at the stage of thermal decomposition leads to a decrease in temperature and time of the chemical reaction until complete decomposition of ammonium nitrate.

Combustion, Explosion, and Shock Waves. 2019;55(4):402-408
pages 402-408 views

X-ray Diffraction Investigation of the Evolution of Dust-Laden Jets from the Metal Surface

Vlasov A.N., Zhuravlev A.V., Pashentsev V.A., Smirnov V.N., Smirnov E.B., Stolbikov M.Y., Cheremazov V.E., Ten K.A., Pruuel E.R., Kashkarov A.O., Rubtsov I.A., Kremenko S.I.

Abstract

Comparative results of experiments aimed at studying the evolution of dust-laden jets induced by the presence of structural elements and grooves on the surface of loaded specimens are reported. The results are obtained with the use of pulsed X-ray diffraction radiography and synchrotron radiation. Information on dust density changes in synchrotron diagnostics is obtained by using multiframe filming. In the case of single-frame recording by means of pulsed X-ray diffraction radiography, a glancing detonation wave was used for studying the dust behavior instead of the normal wave.

Combustion, Explosion, and Shock Waves. 2019;55(4):409-417
pages 409-417 views

Equation of State of TATB Based on Static and Dynamic Experiments

Biryukova M.A., Petrov D.V., Garmashev A.Y., Muzyrya A.K., Kovalev Y.M., Smirnov E.B., Badretdinova L.K.

Abstract

An analytical model of the equation of state is developed based on theoretical ideas about the structure of TATB. ^The model is validated against experimental data obtained in static and dynamic experiments. The theoretically sound equation of state was used to match different experimental data in order to maximize the use of empirical information. It is expected that the use of the equation of state will increase the accuracy of the description of thermodynamic parameters of unreacted TATB in numerical simulations of shock-wave and detonation processes.

Combustion, Explosion, and Shock Waves. 2019;55(4):418-425
pages 418-425 views

Detonation Pressure of an Emulsion Explosive Sensitized by Polymer Microballoons

Yunoshev A.S., Bordzilovskii S.A., Voronin M.S., Karakhanov S.M., Makarov S.N., Plastinin A.V.

Abstract

The detonation pressure of an emulsion explosive sensitized by polymer microballoons was determined using two loading schemes: a detonation wave normally incident on the target and sliding detonation. The initial density of the explosive ranged from 0.2 to 1.2 g/cm3. The obtained pressures are in good agreement with the calculated values known from the literature and are compared with the detonation pressures of an emulsion explosive sensitized by glass microballoons. The reaction time and the isentropic exponent of the emulsion explosive were calculated.

Combustion, Explosion, and Shock Waves. 2019;55(4):426-433
pages 426-433 views

Instability of a Conical Liner during Shaped-Charge Jet Formation

Pai V.V., Titov V.M., Luk’yanov Y.L., Plastinin A.V.

Abstract

Instability of a conical liner during shaped-charge jet formation has been studied. To establish the metal flow pattern during shaped-charge jet formation, we fabricated three-layer copper-copper-Constantan liners consisting of a solid copper conical cone with a cone angle of 45°, a wall thickness 1.5 mm, and a cone pressed into it and rolled from a copper sheet 1.0 mm thick clad on the inside with Constantan 0.2 mm thick by explosive welding. Liner compression was carried out by an RDX charge 20 mm thick. The jet formation process was recorded by flash radiography, and the metal flow pattern was determined by micro sections of recovered slugs. Since the interface between the explosively welded metals is clearly distinguishable in the sections, the residual deformation in different sections of the slug shows the occurrence of liner instability during the compression, which manifested itself as folds oriented along the generatrix of the cone. At the same time, the general flow pattern described in terms of the theory of an ideal incompressible fluid is not disturbed, which follows from radiographs of the shaped-charge jet formation process.

Combustion, Explosion, and Shock Waves. 2019;55(4):434-438
pages 434-438 views

Effect of Mechanical Properties of Materials on Wave Formation in Explosive Welding

Zlobin B.S., Kiselev V.V., Shtertser A.A.

Abstract

Experiments on the explosive welding of low-plasticity steels through thin plastic layers show that, aside from the geometric features of collision (thickness and angle of collision of plates and contact point velocity), the sizes of waves arising in the weld are also highly affected by the mechanical properties of welded materials (hardness, density, and sound velocity). It is determined that waves of different sizes can be formed under the same conditions, but their length lies in a certain range of values. On the basis of the experimental data obtained and with involvement of the Landau model, which describes the instability of a steady flow of viscous fluid, expressions for estimating the upper and lower wavelength limits are constructed with account for both geometric parameters of collision and mechanical properties of colliding metal plates.

Combustion, Explosion, and Shock Waves. 2019;55(4):439-446
pages 439-446 views

Structural Transformations in Aluminum Cylindrical Shells under Dynamic Loading

Koval’ A.V., Shirinkina I.G., Petrova A.N., Brodova I.G., Smirnov E.B., Shorokhov E.V.

Abstract

This paper describes the structural studies of hollow cylindrical shells made of D16 and Al-Mn aluminum alloys, loaded by sliding detonation. Explosive loading conditions for the complete convergence and closure of shells are established. Light optics scanning electron microscopy, and transmission electron microscopy are applied to study the structural and phase transformations in shells under shock wave loading. The relation of composition, structure, and mechanical characteristics of alloys with their behavior under the action of shock loading is shown. There are several scenarios of convergence of shells, depending on their composition and loading conditions—from complete and steady convergence to multiple spalling.

Combustion, Explosion, and Shock Waves. 2019;55(4):447-455
pages 447-455 views

Deformation Phenomena in the Collapse of Metallic Cylindrical Shells. Buckling

Zel’dovich V.I., Frolova N.Y., Kheifets A.E., Khomskaya I.V., Degtyarev A.A., Shorokhov E.V., Smirnov E.B., Dolgikh S.M., Koval’ A.V.

Abstract

The structural mechanisms of buckling and the deformation behavior of copper and steel cylindrical shells (pipes) during collapse under the action of an explosion are studied. The dependence of deformation behavior on the transverse dimensions of the shell and properties of the loaded material is described. It is established that the stability of radial collapse depends on absolute dimensions of the shell rather than relative dimensions, with the collapse of large-diameter shells occurring more stably. It is demonstrated that the collapse stability is violated due to the formation of a characteristic pattern of localized strain in the sample, consisting of homogeneous, orderly arranged structural elements whose dimension depends little on the material properties and experimental conditions. A criterion for stable radial collapse that relates the characteristic dimensions of the structural element of localized strain and the shell radius is proposed.

Combustion, Explosion, and Shock Waves. 2019;55(4):456-465
pages 456-465 views

Numerical Analysis of the Formation of Shaped-Charge Jets from Charges with Conical and Semi-Spherical Liners of Variable Thickness

Ladov S.V., Nikol’skaya Y.M., Fedorov S.V.

Abstract

Studies of shaped charges with hemispherical liners of degressive thickness (decreasing from the top to the base) were continued based on numerical simulation. The possibility of increasing not only the velocity but also the mass of the head elements of shaped-charge jets to the level provided by conical liners of progressive thickness were analyzed. For this purpose, liners of degressive thickness in the form of a truncated sphere and a semi-ellipsoid slightly elongated along the charge axis were additionally studied.

Combustion, Explosion, and Shock Waves. 2019;55(4):466-470
pages 466-470 views

Propulsion Performance and Blast Impulse of Explosive Charges in Near-Field Explosion

Petyukov A.V., Pyr’yev V.A.

Abstract

The results of numerical simulation of the blast impulse of explosive charges on structural elements are presented. The numerical method was validated against available experimental data describing the blast effect in near-field explosion. Additional experiments on explosive acceleration of steel disks were performed. The effect of blasting conditions (the presence or absence of air, additional reflective surfaces) on the blast impulse was studied.

Combustion, Explosion, and Shock Waves. 2019;55(4):471-477
pages 471-477 views

Acceleration Abilities of Combined Explosive Charges Containing Dispersed Aluminum in a Thin Peripheral Layer

Davydov V.Y., Gubin A.S., Tereshchenko M.N., Bodnaryuk A.D.

Abstract

An X-ray pulse video recording method is used to study the acceleration ability of coaxial combined explosive charges containing dispersed aluminum in a thin peripheral layer as compared with charges containing a uniformly distributed aluminum additive and charges with no additives. The significant influence of the burnout of detonation products on the acceleration ability of explosive charges containing dispersed aluminum is confirmed. It is shown that aluminum in a composition with explosive charges burns out because of reacting both with detonation products and ambient air, including in a rarefied environment.

Combustion, Explosion, and Shock Waves. 2019;55(4):478-482
pages 478-482 views

Suspension Detonation Spraying of Ceramic Coatings

Shtertser A.A., Ul’yanitskii V.Y., Rybin D.K.

Abstract

Experiments on detonation spraying of ceramic coatings are for the first time carried out by feeding a powder as a part of a suspension into a barrel. Spraying of Al2O3, TiO2, and hydroxyapatite nanopowders shows that the new method for obtaining coatings (suspension detonation spraying) can be implemented on a CCDS2000 detonation device. Unlike conventional detonation spraying technologies using micron-sized powders, suspension spraying makes it possible to work with powders whose particle size is smaller than a micron and which serve as a basis for preparing a suspension injected into the detonation device barrel.

Combustion, Explosion, and Shock Waves. 2019;55(4):483-490
pages 483-490 views

Explosive Compaction of Chromium Carbide Powders with a Metallic Binder

Krokhalev A.V., Kharlamov V.O., Kuz’min S.V., Lysak V.I., Pai V.V.

Abstract

Fundamental features of explosive compacting of powder mixtures containing high-melting metal carbides and metallic binders are under consideration. The effect of acoustic rigidity of metallic binders on the residual porosity of samples after explosive treatment is revealed. It is shown that the degree of compacting of mixtures of carbide powders with metals under explosive compaction is determined by the possibility of arrival of shock waves in the metallic binder particles at their surfaces free of contacts with other particles and with a mass velocity acquired by the metallic binder at these surfaces due to unloading.

Combustion, Explosion, and Shock Waves. 2019;55(4):491-499
pages 491-499 views

Practical Issues of Safety in Coal Mines

Goffart T.V., Vasil’ev A.A.

Abstract

A number of modern scientific and practical problems in design of multifunctional safety systems for coal mines and requirements to such systems are discussed. The reasons and the dynamics of accidents in mines are analyzed; examples of approaches to preventing such accidents are given. Available and promising directions of the development of engineering tools and systems for ensuring miners’ safety are considered. The efficiency of using the scanning gas monitoring technology is demonstrated. Combining this technology with the automatic system of fire extinguishing allows the fire to be suppressed at the initial stage of ignition of the methane–air mixture.

Combustion, Explosion, and Shock Waves. 2019;55(4):500-506
pages 500-506 views

Laboratory Explosive System for Cylindrical Compression

Dudin S.V., Sosikov V.A., Torunov S.I.

Abstract

One method of studying materials or plasma under pressure pulse loading is axisymmetric compression using a convergent cylindrical detonation wave. Such waves are often generated by multipoint initiation and have a number of specific features that may affect the properties of the test objects. To solve specific problems, it is proposed to use a laboratory explosive system based on a converging cylindrical detonation wave with 12–48 initiation points. The TNT equivalent of the charge is less than 1 kg. The main method of research is visualization using a domestic high-speed Nanogeit camera with a nanosecond time resolution. The structure of the converging detonation wave is shown, and its velocity along the radius is determined. It is shown that for a charge of limited thickness, the curvature of the detonation wave front for various explosives depends only on the distance to the initiation point.

Combustion, Explosion, and Shock Waves. 2019;55(4):507-511
pages 507-511 views