Combustion, Explosion, and Shock Waves
Combustion, Explosion, and Shock Waves is a peer-reviewed journal that presents cutting-edge studies in the physics and chemistry of combustion and detonation processes, structural and chemical transformation of matter in shock and detonation waves, and related phenomena. Each issue contains valuable information on the initiation of detonation in condensed and gaseous phases, environmental consequences of combustion and explosion, engine and power unit combustion, production of new materials by shock and detonation waves, explosion welding, explosive compaction of powders, dynamic responses of materials and constructions, and hypervelocity impact. Combustion, Explosion, and Shock Waves is no longer solely a translation journal. It publishes manuscripts originally submitted in English and translated works. The sources of content are indicated at the article level. The peer review policy of the journal is independent of the manuscript source, ensuring a fair and unbiased evaluation process for all submissions. As part of its aim to become an international publication, the journal welcomes submissions in English from all countries.
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The journal follows the Springer Nature Peer Review Policy, Process and Guidance, Springer Nature Journal Editors' Code of Conduct, and COPE's Ethical Guidelines for Peer-reviewers.
Approximately 10% of the manuscripts are rejected without review based on formal criteria as they do not comply with the submission guidelines. Each manuscript is assigned to at least one peer reviewer. The journal follows a single-blind reviewing procedure. The period from submission to the first decision is up to 3 months. The approximate rejection rate is 15%. The final decision on the acceptance of a manuscript for publication is made by the meeting of the Editorial Board.
If Editors, including the Editor-in-Chief, publish in the journal, they do not participate in the decision-making process for manuscripts where they are listed as co-authors.
Special issues published in the journal follow the same procedures as all other issues. If not stated otherwise, special issues are prepared by the members of the editorial board without guest editors.
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Vol 55, No 6 (2019)
- Year: 2019
- Articles: 18
- URL: https://journals.rcsi.science/0010-5082/issue/view/9167
Article
Flame Propagation and Acoustics
Abstract
An intense effect of acoustic waves on the structure and shape of the burner flame was discovered by Rayleigh. The present paper deals with acoustic waves in the case of flame propagation in a tube. The flame emits acoustic waves generating the flow in the tube. Being actually a wave beam, the flow bounded by the walls experiences friction and also diffraction divergence, resulting in the emergence of secondary waves, i.e., waves of flow disturbances. They induce the formation of a cellular structure of the flame; at high velocities, the flame becomes turbulent. All these processes play important roles in the deflagration-to-detonation transition in tubes. Emission of acoustic waves by the flame is also responsible for the formation of spherical detonation. Spin and pulsed detonation can be interpreted on the same basis.
633-643
Thermochemical and Energy Characteristics of 1,4-Diethynylbenzene
Abstract
The standard enthalpy of formation of 1,4-diethynylbenzene experimentally to be 500.6 ± 6.7 kJ/mol. Calculations show that 1,4-diethynylbenzene has a relatively high adiabatic combustion temperature (about 1970 K at a pressure of 5 atm) and very high heat of combustion in oxygen (42 MJ/kg); therefore, 1,4-diethynylbenzene can be used as the basis to develop an effective dispersing agent of solid fuel that provides an adiabatic combustion temperature of up to 2500 K at a heat of combustion far exceeding the values provided by HMX and the other azides of N-heterocycles previously proposed for this purpose.
644-647
Transition of the Combustion Wave of a Heterogeneous System through a Shaped Obstacle
Abstract
The transition of the combustion wave of a titanium powder layer in air through an inert shaped obstacle has been experimentally studied. It has been shown that an inhomogeneous wave-like structure of the combustion front can form due to the limited supply of gaseous reagents and the thermal instability of combustion of the titanium powder layer. Conditions of the optimal transient combustion mode in the presence of gaseous impurities affecting gas exchange in the reaction zone and the stability of the front in the layered system are obtained. It is shown that there exists a phenomenological criterion for assessing the nature of the transient combustion mode of titanium powder depending on the shape of the inert obstacle and the combustion front.
648-653
Ignition of a Filtration Gas Combustion Wave by a Heated Region of a Porous Medium
Abstract
The ignition of a filtration gas combustion wave by a heated region of an inert porous medium is studied by numerical simulation. The mechanism of formation of the combustion wave is described. Dependences of the time of wave formation on the velocity of the gas mixture, the temperature of the heated region of the porous medium, and its length were obtained. The existence of ignition limits of the filtration combustion wave was found.
654-660
Combustion Hotspots of Energetic Condensed Systems
Abstract
The conditions of occurrence, nature, size, and shape of combustion hotspots of energetic condensed systems and the spatial dynamics of the hotspot combustion wave are discussed. A model for the propagation of hotspot combustion waves in condensed systems is briefly described based on the cellular automata method. A possible explanation for the occurrence of unsteady effects in the combustion of solid rocket propellants is proposed.
661-670
Combustion of Titanium Oxide Based Thermite Systems with a Complex Reducing Agent and an Energy Additive under the Influence of Overload
Abstract
The laws and mechanism of combustion of TiO2 based thermite systems with a complex reducing agent (Al and Ca) under the influence of overload are revealed. The thermite system includes a basic composition whose combustion products are target elements (Ti, Al, Nb, and Cr) and a high-energy additive (CaO2, Al, and Ca) for ensuring high-temperature combustion. With the introduction of an energy additive, the system acquires the ability to burn. With a sufficient content of this additive, the combustion products (TixAly and Al2O3 and CaO oxide solutions) can melt. As the fraction of Ca in the base mixture composition increases, the burning rate drops and the reduction completeness of the target oxides increases. With an optimal ratio of Ca and Al in the mixture, the yield of the target elements in the ingot is close to the calculated value.
671-677
Direct Conversion of Chemical Energy into Electrical Energy in the Combustion of a Thin Three-Layer Charge
Abstract
This paper presents a study of direct conversion of chemical energy into electrical energy during the combustion of a (80Zr + 20CuO)–(LiF + CaF2 + MgF2)–(15Zr + 85CuO) thin three-layer condensed energy system, which is a high-temperature galvanic cell. It is determined that this cell during combustion generates an electric signal with an amplitude of 1.6 V and a half-width of 15 s. Its formation mechanism is proposed. A time-resolving X-ray diffraction method is used to identify the phases formed.
678-685
Effect of Content and Mechanical Activation on the Combustion of a Ni–Al–C System
Abstract
Effect of carbon content in a Ni–Al–C system and preliminary mechanical activation on a burning rate, sample elongation, and mixture yield after mechanical activation, as well as on the structural features of combustion products is under study. Combustion in pressed samples from a mechanically preactivated Ni + Al mixture at room temperature could not be activated. The addition of carbon [2, 4, and 6% (by weight)] into the reacting Ni + Al mixture allows for combustion in Ni–Al–C based pressed samples. Preliminary mechanical activation of the reacting Ni + Al + xC mixture expands a carbon content limit in the mixture at which the combustion of pressed samples is possible. In addition, mechanical activation, as well as an increase in the carbon content in the Ni–Al–C system reduces the burning rate. The observed relationships are explain.
686-691
Electrothermal Explosion of a titanium-soot Mixture under Quasistatic Compression. III. The Effect of Quasistatic Compression Pressure
Abstract
The results of diagnostics of thermal conditions of an electric thermal explosion (ETE) of a mixture of titanium and soot powders under quasistatic compression are presented. The effect of quasistatic compression pressure on the thermal and electrical parameters of an ETE is studied. It is shown that nonuniform heating occurs at low pressure, while uniform heating occurs at high pressure. A criterion is proposed for determining the thermal regime of the ETE of a heterogeneous mixture, based on the ratio of the exothermic interaction times and the electric current variation during a thermal explosion. It is established that the dependence of the electric current variation rate on time has one peak when the sample is heated nonuniformly and two peaks when it is heated uniformly. An abnormally low effective flash point of the heterogeneous titanium-soot mixture is explained.
692-696
Using an Artificial Neural Network to Simulate the Complete Burnout of Mechanoactivated Coal
Abstract
An experimental study of the effect of pulverization on the thermal destruction of coal is carried out. Artificial neural networks are used to develop a model that allows predicting the degree of burnout of pulverized coals with high accuracy (an average relative error of 3% and a determination coefficient of 96%).
697-701
Thermodynamic Estimate of the Optimal Ratio of the Solid Propellant and Fuel in the Gas Generator of a High-Velocity Flying Vehicle
Abstract
A method for calculating the optimal ratio of the fuel and solid propellant in the gas generator of a high-velocity flying vehicle is proposed. A thermodynamic approach is used to describe the processes in the gas generator. The ratio of the solid propellant and fuel in the gas generator is determined by their physical and chemical properties. An increase in the density and heat of combustion of the solid propellant and in the fuel porosity leads to reduction of the volume fraction of the solid propellant in the gas generator. An increase in the density, specific heat, specific heat of sublimation, and temperature of sublimation of the fuel leads to an increase in the volume fraction of the solid propellant in the gas generator.
702-707
Effects of Various Compositions of the Fuel—Air Mixture on the Pulse Detonation Engine Performance
Abstract
The objective of the present analysis is to investigate the effect of gaseous hydrocarbon fuels, such as Octane C8H18, Hexane C6H14, and Pentane C5H12 on the cyclic combustion process in an obstructed channel of the pulse detonation engine. Three-dimensional reactive Navier-Stokes equations are used to simulate the combustion mechanism of stoichiometric hydrocarbon fuels along with a one-step reaction model. The fuel is injected at atmospheric pressure and temperature and is ignited with pre-heated air. The investigation shows that initially a high-temperature combustion wave propagates with the local speed of sound; it creates turbulence after colliding with obstacles, resulting in an increase to supersonic flame speeds. Therefore, different values of the combustion flame propagation speed, combustion efficiency and impulse per unit area are obtained for these fuels. The detonation speed in the hexane-air mixture is about 5.8% lower than the detonation speed predicted by the NASA CEA400 code. However, it is observed that the octane fuel reduces the deflagration-to-detonation transition run-up distance as compared to other fuels.
708-717
Effect of the Density of PETN-Aluminum Composites on the Threshold of Laser Initiated Explosive Decomposition
Abstract
The results of studying the laser induced explosive decomposition thresholds of PETN-aluminum composites depending on the concentration of inclusions at various sample densities are presented. An increase in the density of the samples reduces the minimum critical energy density of explosive decomposition and the concentration of inclusions at which explosions are observed.
718-722
Study on Energy Output Characteristics of Explosives Containing B/Al in the Air Blast
Abstract
It is a key problem to design and prepare metallized explosives of high energy and low sensitivity. In order to study the effect of the content of the boron/aluminum (B/Al) compound powder on the energy output property of metallized explosives in the air blast, three HMX-based explosives containing B/Al were designed and prepared. Air blast tests of cylindrical samples are performed, accompanied by numerical simulations by the finite element program LS-DYNA. The results show that the shock wave overpressures of explosives containing B/Al are higher than those of explosives containing Al under the same conditions. The deviations between the values calculated by the empirical equation and the measured values are smaller than 3.5 kPa, and the deviations between the values obtained in numerical simulations and the measured values are smaller than 4.9 kPa. Although the Al powder can enter the reaction with detonation products and air easier, the burning time of the boron powder is longer and the released energy is larger. Moreover, as the content of the B/Al compound powder increases, the burning time becomes longer, and the aftereffect work ability and the damage effect become stronger.
723-731
Sound Velocity in Shock-Compressed Samples from a Mixture of Micro- and Nanodispersed Nickel and Aluminum Powders
Abstract
Sound velocity variation behind a shock wave front is measured in pressed samples of micro- and nanodispersed mixtures of nickel and aluminum powders at pressures of 10, 30, and 60 GPa in order to verify the possibility of a reaction with the formation of nickel aluminide in a submicrosecond time range. It is shown that, in a pressure range of up to 60 GPa, the sound velocity in the samples from a nanodispersed mixture is higher than in the samples from a mi-crodispersed mixture. Moreover, upon reaching 60 GPa, the sound velocities in both mixtures with account for errors are practically equalized, which is related to melting of the samples. Based on the data obtained, it is concluded that there is no noticeable progress of the Ni + Al reaction during less than 1 μs.
732-738
On the Penetration Capability of Shaped Charges with Conical and Hemispherical Liners
Abstract
This paper presents a computational comparison of the penetration capability of two shaped charges—with conical and hemispherical (degressive thickness) liners. It is shown that close values of the penetration capability of the charges are provided only in the ideal case of strictly axisymmetric motion of shaped-charge jets.
739-743
Effect of Explosion on the Mechanical Properties of 110G13L Steel
Abstract
Shock loading is an effective method of bulk hardening of materials. This study of the structure and mechanical properties of 110G13L steel before and after explosion loading showed that the mechanical characteristics reached maximum values at the surface of the explosively treated material: Vickers hardness HV =480, yield strength of 850 MPa, and tensile strength of 1240 MPa. The thickness of the hardened layer was ≈40 mm. For steel without shock loading, the above parameters had the following values: HV =240, yield strength of 355 MPa, and tensile strength of 840 MPa. Metallographic studies revealed that the number of slip lines in grains decreased with distance from the explosive loading surface.
744-749
Jet Penetration Effect of an Inward-Cutting Circular Shaped Charge with Different Number of Detonation Points
Abstract
The breach of a steel column target (Steel 45, 120 mm in diameter) by an inward-cutting circular shaped charge is considered. The jet penetration process is simulated by a 3D model run in the ANSYS/LS-DYNA program. The results are compared with actual tests, where photographs of the jet penetration process allowed observation of detonation forms, timing of the jets arising at the cross section of the detonation points, and detonation wave collision points. Different penetration effects are observed with 2-, 4-, or 8-point symmetrical synchronous initiation of detonation. With 2-point initiation, the circular-shaped charge can basically cut off the steel column target, but 4- and 8-point initiation is more effective. A greater number of detonation points provides more detonation wave collision points, higher jet velocity, earlier jet-target contact, greater penetration depth, and more rapid cutting of the target.
750-758