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Combustion, Explosion and Shock Waves

2002 year, number 2

1.
Inhibition of Methane–Oxygen Flames by Organophosphorus Compounds

O. P. Korobeinichev, V. M. Shvartsberg, T. A. Bol'shova, A. G. Shmakov, D. A. Knyaz'kov
Institute of Chemical Kinetics and Combustion, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090; korobein@ns.kinetics.nsc.ru
Pages: 127-133

Abstract >>
For CH4/O2 flames doped with trimethyl phosphate (TMP), the flame structure is examined and the velocity of flame propagation is determined with the aim of studying the mechanism of inhibition of flames doped with organophosphorus compounds. The structure of a methane–oxygen flame doped with TMP stabilized on a flat burner at a pressure of 1 atm was studied. The dependence of flame propagation velocity on the concentration of TMP is measured using a Mache–Hebra burner to determine the effectiveness of a number of TMP as a flame inhibitor. The mechanism of destruction of TMP in flames was used to model the flame structure and calculate the velocities of propagation of a methane–air flame as functions of the initial concentration of TMP. Calculation and experimental results are compared.



2.
Numerical Simulation of Thermochemical Conversion of a High-Ash Coal in a Low-Temperature Fluidized Bed under Pressure

V. P. Patskov
Scientific–Technological Center of Coal Power Technologies, National Academy of Sciences and the Ministry of Fuel and Energy of Ukraine, Kiev 04070, Ukraine; CETC@i.kiev.ua
Pages: 134-142

Abstract >>
The paper considers a mathematical model, an algorithm, and a program for calculating nonstationary processes of air gasification of a high-ash coal under pressure in a pilot-scale circulating fluidized bed gasifier reactor. The effect of operation parameters on the course of the process is analyzed. It is shown that "hot spots" (short-duration local heatings) can form at various points of the bed, at which maximum temperature can be close or even exceed the fluid slagging point. Possible mechanisms of formation of "hot spots" are analyzed.



3.
Unsteady Combustion Regimes of Gasless Systems with a Low-Melting Inert Component

V. G. Prokof'ev and V. K. Smolyakov
Department of Structural Macrokinetics, Tomsk Center of Science, Siberian Division, Russian Academy of Sciences, Tomsk 634050; maks@fisman.tomsk.su
Pages: 143-147



4.
Formation of the Macroscopic Structure of the Product of SHS under Compaction

V. K. Smolyakov and O. V. Lapshin
Department of Structural Macrokinetics, Tomsk Scientific Center, Siberian Division, Russian Academy of Sciences, Tomsk 634055; maks@fisman.tomsk.su.
Pages: 148-156

Abstract >>
A mathematical model is constructed for compaction of a reacting heterogeneous mixture under continuous loading. A two-component mixture containing a low-melting component is considered. Compaction of the stoichiometric mixtures is analyzed in detail. Formulas for the dynamics of structural transformations and macroscopic characteristics of the product are obtained. It is established that there are different regimes of the process, depending on synthesis conditions, physicochemical parameters of the mixture, and the load.



5.
Combustion of Mixtures of Commercial Aluminum Powders and Ultrafine Aluminum Powders and Aluminum Oxide in Air

E. M. Popenko, A. P. Il'in,* A. M. Gromov,** S. K. Kondratyuk,** V. A. Surgin, and A. A. Gromov*
Biisk Technological Institute, Altai State Technical University, Biisk 659305;
*High-Voltage Institute, Tomsk Polytechnical University, Tomsk 634050; yellow@mail2000.ru;
**Federal Scientific and Production Center "Altai," Biisk 659322
Pages: 157-162

Abstract >>
The paper studies the combustion of mixtures of commercial aluminum powders (ASD-1 and ASD-4) and ultrafine powders of Al and γ-Al2O3 in air. It is shown that the combustion of coarsely dispersed commercial powders is accompanied by binding of air nitrogen with formation of AlN and AlON. The combustion of mixtures proceeds in two stages with the possible formation of intermediate gaseous and liquid products. The processes of sintering and incomplete combustion play an important role in the combustion of mixtures of commercial powders and ultrafine powders of aluminum.



6.
High-Temperature Oxidation of Metals with Allowance for Radiative Heat Transfer

V. V. Kalinchak, S. G. Orlovskaya, T. V. Gryzunova, and N. N. Kopyt
Mechnikov Odessa National University, Odessa 65026, Ukraine; kalin@dtp.odessa.ua
Pages: 163-168

Abstract >>
The influence of radiation on the characteristics of high-temperature and hysteresis oxidation regimes for a metal particle with an oxide film in a condensed state on its surface is studied. Conditions are defined under which radiative heat exchange with cold walls of the reactor decreases the burning temperature, critical temperatures, and oxide-film thickness, i.e., parameters characteristic of ignition and forced and spontaneous extinction of a metal particle.



7.
Mechanism and Microkinetics of Soot Formation upon Thermal Decomposition of Carbon and Fiberglass Plastics under One-Sided Radiant-Convective Heating

G. N. Isakov
Institute of Applied Mathematics and Mechanics, Tomsk State University, Tomsk 634050; isak@niipmm.tsu.tomsk.su
Pages: 169-175

Abstract >>
The paper reports experimental methods for studying soot formation upon thermal decomposition of carbon and fiberglass plastics in flows of high-temperature gas and flame. The mechanism of the process is analyzed and its microkinetic parameters are determined. The problem of unsteady heating of a semi-infinite body of semitransparent fiberglass plastic is formulated and solved numerically taking into account the process of soot formation under conditions of radiant-convective heat transfer. A comparison of calculation results with experimental data is given in dimensionless variables.



8.
Estimating the Electromotive Force in a Condensed-System Combustion Wave

V. F. Proskudin
Russian Federal Nuclear Center, Institute of Experimental Physics, Sarov 607190; Proskudin@dep19.vniief.ru
Pages: 176-181

Abstract >>
A method for recording values of the electromotive force (e.m.f.) in a combustion wave in conducting condensed systems is proposed. The method uses electrodes made of the solid combustion products of the condensed system studied. The e.m.f. in the combustion wave in the 3Zr + 2WO3 and Ti + C + 20% TiC systems were measured to be 70–80 and 24–27 mV, respectively (the e.m.f. for these systems has different polarity). It is shown that in the combustion wave of the Al + Ni system, the e.m.f. is close to zero (does not exceed 1–2 mV).



9.
Structure of the Burning Surface of Powder under Conditions of Blowing

S. V. Finyakov
Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow 117977
Pages: 182-193

Abstract >>
The surface structure (roughness) of ballistite powder burning under conditions of blowing past the surface is studied. The parameters varied in experiments are the caloricity of powders, the burning rate, the pressure, and the blowing velocity. Regular macroscopic roughness is found on all the specimens examined. A dependence of the roughness height on the blowing velocity and pressure is established. A formula for evaluation of the reduced height of the roughness is derived. Based on the analysis of experimental data, a hypothesis on the roughness-formation mechanism under conditions of blowing is proposed.



10.
Initiation of a Charge of a Gel-Like Reactive Substance by an Electric Explosion. Part 1. Thermal Processes

V. V. Burkin and R. S. Burkina*
Institute of Applied Mathematics and Mechanics, Tomsk State University, Tomsk 634050
*Tomsk State University, Tomsk 634050; roza@ftf.tsu.ru
Pages: 194-200

Abstract >>
Ignition of a reactive substance by a high-temperature discharge cavity is analyzed by an asymptotic method. The effect of heat transfer into the lateral surface of the charge and decrease in the intensity of the radiant flux from the cavity on the moment and critical conditions of ignition is studied. Calculation results are compared with available experimental data.



11.
Initiation of a Charge of a Gel-Like Reactive Substance by an Electric Explosion. Part 2. Hydrodynamic Processes

V. V. Burkin and R. S. Burkina*
Institute of Applied Mathematics and Mechanics, Tomsk State University, Tomsk 634050
*Tomsk State University, Tomsk 634050; roza@ftf.tsu.ru
Pages: 201-205

Abstract >>
The wave pattern produced by an electric explosion of flat foil embedded in a semi-infinite cylindrical charge of a gel-like substance is numerically studied. Hydrodynamic parameters are calculated for various initial positions of the foil and parameters of the electric explosion.



12.
Interaction of a Shock Wave with a Cloud of Aluminum Particles in a Channel

T. A. Khmel' and A. V. Fedorov*
Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090; khmel@itam.nsc.ru
*Novosibirsk State University of Architecture and Construction, Novosibirsk 630008; fedorov@ngasu.nsk.su;
*Institute of Theoretical and Applied Mechanics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090
Pages: 206-214

Abstract >>
Interaction of an incident shock wave (with a rectangular or triangular profile behind its front) with a finite-width semi-infinite cloud of aluminum particles located in a channel along the plane of symmetry is numerically simulated. Shock-wave interaction with the leading edge of the cloud results in the formation of a vortex that leads to cloud dispersion. Reflection of the curved shock wave from the plane of symmetry may be regular or may include the formation of the Mach stem. If the cloud is loaded by a rather strong shock wave, a detonation wave is formed in the cloud. In this case, the flow is periodic, which is caused by passing of transverse waves and their reflection from the walls.



13.
Passage of a Bubble-Detonation Wave into a Liquid

A. I. Sychev
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090
Pages: 215-218

Abstract >>
The passage of a detonation wave from a chemically active bubble media into a chemically inert medium (liquid) is studied experimentally. The structure of the transmitted wave and the wave reflected from the butt-end of a shock tube (post-detonation waves) is investigated, and the pressures of these waves for different liquids are measured. The evolution of the post-detonation waves is traced, their velocities are measured, and the attenuation constants of these waves are determined. The energy-dissipation mechanisms for post-detonation waves in liquids are analyzed qualitatively.



14.
Detonation Properties and Electrical Conductivity of Explosive-Metal Additive Mixtures

S. D. Gilev and A. M. Trubachev
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090; gilev@hydro.nsc.ru
Pages: 219-234

Abstract >>
Detonation properties of mixtures of condensed high explosives with metal additives are studied. A scheme of measurement of high electrical conductivity of detonation products (σ10 Ω-1



15.
Deceleration of Detonation Products of a TATB-Based High Explosive

Yu. A. Aminov, M. M. Gorshkov, V. T. Zaikin, G. V. Kovalenko, Yu. R. Nikitenko, G. N. Rykovanov
Russian Nuclear Physics Center, Institute of Technical Physics, Snezhinsk 456770; Yu.A.Aminov@vniitf.ru
Pages: 235-238

Abstract >>
Deceleration of detonation products of a TATB-based high explosive is studied by a modified target method. Experimental results obtained are compared with data for a high explosive with similar composition and calculation results.



16.
Evolution of the Microstructure of Dynamically Loaded Materials

M. P. Bondar'
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090; bond@hydro.nsc.ru
Pages: 239-247

Abstract >>
The paper deals with the evolution of the microstructure in materials after explosive loading by the method of a hollow thick-walled cylinder. The materials considered differ in the type of crystal lattice and initial state (grain size and initial defect density). The role of crystal structure in the formation of the microstructure of single crystals and coarse-grain copper specimens formed under explosive deformation is investigated. The microstructures formed are compared with the corresponding strains. It is shown that during high-rate deformation, fragmentation of the structural elements occurs at all scale levels. The fragmentation mechanism and the associated properties depend on the initial structure and state of the material. The special features of the microstructure evolution in materials revealed in this work are taken into account in producing new materials by dynamic and quasidynamic methods.



17.
Dynamic Anticumulative Protection. II

B. V. Voitsekhovskii, V. L. Istomin and V. A. Ryzhakov
Lavrent'ev Institute of Hydrodynamics, Siberian Division, Russian Academy of Sciences, Novosibirsk 630090
Pages: 248-251

Abstract >>
Various types of dynamic anticumulative protection and the effect of its parameters on jet penetration into a target were studied.