A. A. Vasil'ev1,2, V. A. Vasiliev1 1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: multi-fuel systems, initiation, critical energy, fuel-lean and fuel-rich systems, explosion hazard, ecology, carbon footprint reduction, engines operating on gaseous fuel species
Data on the parameters of combustion and detonation of single-fuel systems methane-oxygen (air) and hydrogen-oxygen (air), as well as double-fuel systems methane-hydrogen-oxygen (air) with variation of the ratio between the initial species are presented. The influence of combustible system preheating on the parameters of detonation and combustion products is analyzed for fuel-lean, stoichiometric, and fuel-rich mixtures. It is found that preheating has a strong effect in fuel-lean combustible systems, which is manifested as reduction of the critical energy of initiation by several orders of magnitude.
The effect of different obstacle positions on the explosion flame dynamics of hydrogen-air mixtures with concentration gradients is investigated by numerical simulations. The numerical simulations predict explosion characteristic parameters matching correctly with the experimental results. The calculation results show that the influence of the obstacle position on the explosion flame of an inhomogeneous mixture is more significant compared to that of a homogeneous mixture. The analysis of the flame morphology and flow field reveals that, as the obstacle position increases, the premixed flame undergoes more complex deformation after passing through the obstacle and generates eddies near the obstacle under the action of vortices. By comparing the flame front position and peak overpressure after the explosion, it is found that, as the obstacle position increases, the concentration gradient has a stronger inhibitory effect on flame propagation. The influence of the concentration gradient on the peak overpressure is more pronounced when the obstacle is 200 mm from the ignition point. This research can provide theoretical guidance for industrial explosion protection and safety management.
N. V. Nevmerzhitskii, A. N. Razin, V. V. Zmushko, E. D. Senkovskii, E. A. Sotskov, K. V. Anisiforov, E. V. Levkina
RFNC, All-Russian Research Institute of Experimental Physics, Sarov, Russia
Keywords: air-water interface, shock wave, instability, turbulent mixing
This paper presents experimental and calculated results of studying the development of turbulent mixing at the air--water interface after the passage of an oblique shock wave. The shock-wave Mach number in the experiments varied in the range 2-2.3. The angle of inclination of the shock wave front to the interface was 0,15 °C, and 30 °C. When the shock wave was incident on the water surface, Kelvin-Helmholtz instability developed, which over time led to turbulent mixing of the substances in contact. In the experiments, the flow field structure was recorded by high-speed video cameras. It was found experimentally that with increasing angle of incidence of the shock wave on the interface, turbulent mixing increased and the droplet size of the dispersed liquid decreased due to more intense droplet fragmentation. Numerical modeling of the experiments using a two-dimensional technique shows that the technique satisfactorily predicts the dynamics of the turbulent mixing zone in the vicinity of the interface.
A. O. Sivakova1, P. A. Lazarev1, O. D. Boyarchenko1, A. E. Sychev1, G. A. Sychev2 1Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia 2Joint Institute for High Temperatures (JIHT), Russian Academy of Sciences, Moscow, Russia
Keywords: self-propagating high-temperature synthesis, combustion, Al-Mn-Si, microstructure, intermetallic alloy, solid solution
This paper is devoted to the preparation of Al-Mn-Si-based compounds with different Si contents (0, 5, 10, and 15 at.%) using self-propagating high-temperature synthesis (SHS). This method is used for the first time to obtain the Al9Mn3Si γ-phase with a hexagonal crystal lattice (P63/mmc space group) as part of a synthesized alloy with a content of 15 at.% of Si in the initial mixture. The X-ray diffraction analysis of the synthesized alloys from mixtures with a silicon content of 5-10 at.% also shows the presence of γ2-Al8Mn5 (trigonal, R3m space group) and MnSi (cubic, Pm-3m space group) phases. The phase formation of intermediate compounds at silicon content in a mixture below 15 at. % may be associated with combustion temperature, which is insufficient for complete interaction of the system components. Synthesized alloys are characterized by a porous structure with pore size up to 20 μm and a grain size in the pore space of 10-90 μm.
O. G. Glotov1,2, N. S. Belousova1,2, G. S. Surodin1 1Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: aluminum agglomerate, diameter, combustion in air, combustion time, oxide combustion residue of parent agglomerate particle, diameter and mass of oxide residue
A method for obtaining burning aluminum agglomerate particles with a diameter of 215-840 μm is described, and their combustion in free fall in air at atmospheric pressure has been studied. The combustion time as a function of particle diameter was determined by processing video recordings of the combustion process. The morphological and granulometric characteristics of condensed products (large residues of combustion of agglomerates) - final oxide particles were investigated. The ratios of the diameters and masses of the oxide residue and initial agglomerate particles were determined. An empirical formula for estimating the density of the final oxide particles is proposed.
N. A. Kochetov
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: combustion, mechanical activation, SHS, titanium diboride, titanium carbide
The effects of the content of Ti + 2B and Ti + C mixtures and mechanical activation (MA) on the burning rate, the yield of the mixture after MA, and the morphology and phase composition of combustion products of the (Ti + 2B) + (Ti + C) composition has been investigated. During Mechanical activation of the Ti + 2B mixture for 5 min leads to mechanochemical synthesis of TiB2 product. Mechanochemical synthesis does not occur when adding Ti + C powder to the activated Ti + 2B mixture. Increasing the content of Ti + C in the (Ti + 2B) + (Ti + C) mixture leads to deterioration of the compressibility of samples after MA. The burning rate of the initial (Ti + 2B) + Ti + C) mixtures decreases with increasing content of Ti + C. Samples of the combustion products of the initial mixtures retain integrity after the synthesis. Mechanical activation doubles the burning rate of samples from the Ti + C mixture. The burning rate of the activated Ti + 2B) + (Ti + C) mixture increases with increasing content of Ti + C, and samples of the products are dispersed during combustion. For a mixture of equal mass fractions of the initial Ti + 2B powder and the activated Ti +C powder, the dependence of the burning rate of the mixture on the content of Ti + C in it has a minimum; if the investigated composition is dominated by the Ti + 2B mixture, the product samples retain integrity.
S. G. Vadchenko, Yu. S. Vergunova, A. S. Rogachev, I. D. Kovalev, D. Yu. Kovalev
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: high-entropy alloys and carbides, thermal explosion, high-energy mechanical treatment
The influence of the method and duration of mixing of the refractory metals Ta, Mo (Ti), Nb, V, and W with carbon (soot) on the formation of high-entropy carbides in the thermal explosion mode was investigated. The ignition temperature of the mixtures and the composition of the resulting products were determined depending on the method of preparing mixtures of metals with soot. Among the investigated methods of obtaining TaTiNbVWC5 and TaNbVMoWC5 high-entropy carbides, the multistep method of mixture preparation has been shown to be the most efficient. In the first step, a high-entropy solid solution of metals is prepared by high-energy mechanical treatment, after which soot is added to it and additional high-energy mechanical treatment is carried out. Thermal explosion of this mixture results in high-entropy carbides.
D. A. Tropin
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: hybrid detonation, boron particles, hydrogen-air mixture, detailed kinetics, PSU model of boron combustion, numerical simulation
The structure of hybrid detonation waves in gas suspensions of boron particles in hydrogen-air mixtures of different compositions is calculated using the detailed kinetics of hydrogen combustion and the PSU-model of boron particle combustion. The effect of particle diameter and concentration on detonation wave velocity in a stoichiometric hydrogen-air mixture is revealed. It is shown that particles with a diameter of less than 5 μm enhance detonation waves in stoichiometric and rich mixtures, and those with a diameter of more than 10 μm only weaken detonation. The effect of the gas mixture composition on detonation processes is studied. It is revealed that, as the amount of oxidizer in the mixture decreases, the maximum detonation velocity decreases and shifts toward lower volume concentrations of particles.
E. A. Chudakov1, S. A. Finyushin2, A. E. Safronov2, A. M. Tarasov2, L. V. Chernov1, D. N. Zamotaev2, V. V. Barabin2, V. N. Knyazev2, E. N. Bogdanov2 1Nizhny Novgorod State Technical University, Nizhny Novgorod, Russia 2All-Russian Scientific Research Institute of Experimental Physics (VNIIEF), Sarov, Russia
Keywords: laser heterodyne interferometer, barrel loaders, shock-wave compression
Data are presented on the adaptation of photonic doppler velocimetry (PDV) for gas-dynamic studies using barrel loaders. Measuring channels are time-matched via direct measurements of relative time corrections of PDV with an accuracy of up to 0.1 ns using the correlation analysis of the transit time of femtosecond pulses with different repetition periods through the measured fiber lines. The angle of impact of the projectile with the sample studied is determined using a linear regression method, which allows for the most complete use of the entire volume of experimental data and statistical determination of confidence intervals of the estimates obtained. Reliable recording of elastic wave parameters is carried out using a method of active-passive diagnostics of the PDV, which allows one to completely eliminate the interfering reference line and, accordingly, to increase the time and velocity resolution of the PDV.
W. Xiao1, X.-X. Wu1, P. Liu1, T. Jiang1, K.-S. Huang1, X.-L. Bi1, B.-L. Wang2 1Chongqing Hongyu Precision Industrial Group Co., Ltd, Chongqing, China 2Nanjing University of Science and Technology, Nanjing, China
Keywords: thermobaric explosive, afterburning reaction, near-ground explosion, Mach triple point, fireball temperature, oxidizer
In this paper, the effect of oxidizers on the near-ground explosion performance of HMX-based thermobaric explosives (charges' mass of 500 g) are studied by means of experiments and numerical calculations. The trajectory of the Mach triple point motion shows that its height dramatically increases above the incidence angle of 70 °C. The Mach stem exceeds the height of the explosion centre at a distance greater than 3.6 m. The experimental results show that the temperature distribution on the fireball surface is asymmetrical, and the temperature of the upper fireball is higher than that of the lower fireball. The peak temperature of the thermobaric explosive is higher than 2400 K, and the fireball temperature is above 400 K for nearly 1000 ms. The oxidizers, i.e., potassium perchlorate and Fe2O3 slightly enhance the overpressure of the incident wave and significantly prolong the barotropic duration. In addition, potassium perchlorate can quickly participate in the afterburning reaction, while polytetrafluoroethylene is less efficient. The energy released by the thermite reaction of Fe2O3 contributes to the maintenance of temperature, especially the late fireball temperature.
E. N. Bogdanov, A. A. Stanovov, E. A. Chudakov, V. N. Knyazev, R. A. Voronkov, L. I. Kanunova, T. A. Govorunova, V. I. Burenin, A. O. Yagovkin, L. K. Antonyuk
All-Russian Scientific Research Institute of Experimental Physics (VNIIEF)
Keywords: equation of state, explosive, explosion products, modeling, heterodyne interferometer
A method for studying the propelling effect of explosion products of condensed explosives is proposed and substantiated by calculations. This effect allows for a wide range of states on the isentrope of explosion products: from pressures and densities in the range of the Chapman-Jouguet state to a pressure of ≈0.1 GPa and a density of ≈0.2 g/cm3. This method is applied to perform experimental studies of the propelling effect of TG 25/75 explosion products, in which information on the movement of thin aluminum liners is recorded by a PDV multichannel heterodyne-interferometer.
Y. B. Li1, J. X. Wang1, L. Liu2, R. M. Chen2, J. L. Wang2, K. Tang1, H. F. Wang1 1National Key Laboratory of Transient Physics, Nanjing University of Science and Technology, Nanjing, China 2China North Vehicle Research Institute, Beijing, China
Keywords: EFP, shell structural parameters, soft recovery, numerical simulation, experimental study
To study the effect of the height and thickness of a steel shell on the velocity of an explosively formed projectile (EFP), an EFP forming test is carried out, the EFP velocity is tested, and the EFP is soft recovered. The results show that the influence of the shell on the EFP velocity is mainly concentrated in the upper part of the liner. If the shell height is 0.5 times the charge height, the EFP velocity can reach more than 90% of its velocity in a situation where the shell height is equal to the charge height. By removing the lower half shell of the EFP warhead, the overall mass of the warhead can be effectively reduced without significantly affecting the EFP velocity.
P. Kumar1, S. Kumar Ghosh1, S. Saravanan2, J. Deb Barma1, R. K. Bhogendro Meitei1 1Department of Mechanical Engineering, National Institute of Technology, Agartala, India 2Department of Mechanical Engineering, Annamalai University, Annamalai Nagar, India
Keywords: explosive welding, dissimilar-alloy composite, microstructure, mechanical properties, corrosion
The present study is focused on joining Al 5052 (aluminium alloy) and AZ31B (magnesium alloy) with and without silicon carbide particles (SiC(p)) through explosive welding. The scanning electron microscopy image of the weld interface reveals the formation of a molten zone and pores in the AZ31B and Al 5052 weld (without SiC(p) particles), whereas they are absent if SiC(p) is introduced between the alloys. The X-ray diffraction analysis reveals Al12Mg17 and AlMg intermetallic compounds in the conventional weld (without SiC(p)), whereas no intermetallic compounds are detected in the silicon carbide reinforced weld. The maximum microhardness is witnessed close to the interface due to significant plastic strains of colliding plates. The shear (124.5 MPa) and tensile (201 MPa) strengths of the silicon carbide reinforced weld are higher than those of the conventional weld without SiC(p) particles (104~MPa and 135~MPa, respectively). Concerning the corrosion behavior, after 120 days of immersion of samples in the marine broth solution, the weight reduction is negligible (0.01692 g/cm2).
J.-Y. Yi1, R.-J. Hao1, H.-J. Chen2, S.-M. Guan1, S.-Q. Che3 1College of Electromechanical Engineering, North University of China, Taiyuan, China 2Chongqing Hongyu Precision Industry Group Co, Ltd, Chongqing, China 3Jinxi Industries Group Corporation Ltd, Taiyuan China
Keywords: impact velocity, impact angle, destruction mode, fixed steel target.
To study the damage effect of cylindrical charges on steel plates at different impact velocities and angles, a numerical simulation study on the damage effect of cylindrical charges on a steel target plate is carried out at impact velocities of 0-800 m/s and impact angles of 0-90 °C without changing the vertical distance between the center of the cylindrical charge and target plate. It is demonstrated that four main damage modes of the steel plate exist in this case: plastic deformation, boundary tearing, tear at the center of the steel plate, and petal-shaped break. At a zero impact velocity, the damage pattern of the target plate is not affected by the impact angle, and it is plastic deformed. With an increase in the impact angle, the maximum deflection of the steel plate decreases first and then increases; with an increase in the impact velocity of the charge, at the impact velocities of 200 and 400m/s and the impact angles greater than 75oC, the damage mode of the steel plate is no longer plastic deformation, but boundary tear or central petal damage. With an increase in the impact velocity, the energy acting on the plate increases; hence, the energy density affecting the plate also increases. As a result, the breaking effect of the charge on the plate always increases with increasing impact velocity.
F. A. Bykovskii1, S. A. Zhdan1,2, E. F. Vedernikov1 1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: continuous spin detonation, ammonia, air, hydrogen, transverse detonation waves, annular combustor
Regimes of continuous spin detonation of carbonless ammonia-air mixtures in a flow-type annular cylindrical combustor 503 mm in diameter have been obtained for the first time.
V. P. Zamuraev, A. P. Kalinina
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: combustion, hydrogen, hydrocarbon fuel, high-velocity flow, throttling jet, transonic mode
The control of combustion by throttling jets in a two-section channel with high-velocity flow has been studied numerically. Pulses of the first throttling jet are used to produce intense transonic combustion of hydrocarbon fuel in the first section. Side fuel supply is applied after the switching-off of the first jet to maintain the combustion mode before the channel expansion. The completeness of fuel combustion in the second section is increased using a second throttling jet. The Reynolds-averaged Navier-Stokes equations closed by the eturbulence model are solved. Combustion was modeled by the overall reaction. A pulsating mode of hydrogen combustion in the second section when exposed to the cold throttling jet was established. The influence of this jet on the completeness of hydrogen combustion was studied.
A. V. Pinaev, P. A. Pinaev
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: vertical channel, combustion wave, methane, coal dust, dual-fuel heterogeneous mixture, lower flammability limit, flame spread, fire safety
We investigated the possibility of the existence of combustion waves in CH4/air mixtures with a methane content α = 5-8 vol.% and in CH4/air/coal dust mixtures in a closed vertical channel 6.75 m long and 0.07 m in diameter when ignited at the top. The experiments were carried out at an initial pressure of 0.1 MPa using dust with an average volume concentration of 100-530 g/m3 and a particle size 0-200 mm. It was found that combustion was not initiated in gas and gas/coal dust mixtures with α ≤5-5.5 vol.%. The results of the study indicate that the direction of gravity influences the ignition and combustion of the mixtures and that the energy contribution of coal particles is low compared to that of methane.
A. A. Vasil'ev1,2, V. A. Vasil'ev1 1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: explosion hazard, inhibition and suppression of unwanted explosion processes, inhibitors, promoters, initiation, critical energy, lean and rich fuel mixtures, ecology, carbon footprint reduction, gas fuel cell engines
This paper presents new data on the detonation parameters of lean, stoichiometric, and rich methane-oxygen (air) and hydrogen-oxygen (air) mixtures inhibited by nitrogen and carbon dioxide. By varying the ratio between the initial components, carbon dioxide was found to have a stronger inhibiting effect on the parameters of combustion and detonation products.
V. V. Pai1, Ya. L. Luk'yanov1, V. Yu. Ulianitsky1, D. K. Rybin1, I. S. Batraev1, S. V. Khaustov2, S. V. Kuz'min2 1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Volgograd State Technical University, Volgograd, Russia
Keywords: detonation spray, thermocouple, heat flow
An experimental study was performed to investigate thermal processes during gas detonation coating. Before impact on the target, particles of the sprayed material were accelerated to velocities of 300-500 m/s by the flow of detonation products of a gas mixture whose temperature reached 4200 °C. Due to intense heat transfer, the temperature of the particles increased. The highest quality coating was obtained at a heating temperature close to the melting point. Therefore, to estimate the heating temperature of the particles, we measured the heat fluxes from the detonation products of the gas mixture to their frontal and lateral surfaces using a method based on the Seebeck effect.
D. A. Yagodnikov1, V. N. Zaitsev1, I. V. Lokhanov1, A. O. Novikov1, I. A. Larionov2, A. Yu. Gryaznov2, N. N. Potrakhov2 1Bauman Moscow State Technical University, Moscow, Russia 2Ulyanov (Lenin) St. Petersburg State Electrotechnical University (LETI), St. Petersburg, Russia
Keywords: solid rocket motor, interior ballistics, diagnostics, radiography
An X-ray radiography method for contactless diagnostics of solid rocket motors (SRM) is presented. An experimental study was performed to visualize intrachamber processes and determine the solid propellant burning rate in a model E-5-0 SRM using an X-ray system consisting of an X-ray source and a dynamic X-ray detector located at a given distance from the object of study. The possibility of contactless determination of the propellant burning rate based on an analysis of gray level changes near the burning surface was confirmed experimentally. Radiographic results are in satisfactory agreement with the results of other methods for determining the solid propellant burning rate.
S. Yu. Naryzhnyi, V. Yu. Dolmatov, A. S. Kozlov, V. V. Fomenko, G. V. Semashkin, V. A. Marchukov, S. V. Desyatov, M. D. Klimov
SKTB Tekhnolog, Saint Petersburg, Russia
Keywords: paste-like propellant, detonation nanodiamond, multiwalled carbon nanotube, soot, activated carbon, graphite, adamantane, graphene, burning rate, specific impulse
Effect of carbon additives on burning rate of model composite propellants is studied. Paste-like propellant compositions are used, which are an analog of composite solid fuel with an uncured binder. The role of nanocarbon additives is played by different substances: detonation nanodiamond (DND), which is sometimes heat-treated or crushed to a size of 4 nm, multilayer carbon nanotubes, soot, activated carbon, graphite, adamantane, and graphene. Among all the allotropic forms of carbon, the maximum increment of the burning rate (23%) is ensured by an additive of 2% DND with 2% plasticizer (by weight). At the same time, the combustion product temperature decreases by ≈200 °C, thereby reducing the probability of rocket engine burnout.
A. P. Ershov
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: detonation, explosion, carbon, coagulation
The growth of particles behind the detonation wave front in condensed explosives has been investigated based on physical estimates and experimental results obtained in recent years. The focus is on the large difference in particle size due to the presence or absence of hydrogen in the explosive composition.
I. A. Bedarev
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: multifront detonation, detonation initiation, numerical modeling, detonation initiation energy
A computational method has been developed to model the shock-wave mechanism of detonation wave initiation during the interaction of a fast flying body (FFB) with a combustible hydrogen-oxygen mixture diluted with 50% argon under normal conditions. The FFB velocities at Mach numbers M = 3-4 are considered, which are lower than the Chapman-Jouguet detonation velocity in the mixture under study at normal pressure and temperature. It is shown that the detonation wave is initiated at a FFB velocity exceeding M = 3.9. In this case, the shock-wave mechanism of detonation initiation occurs where a detonation wave is formed at the shock wave separated from the combustion wave by an induction zone. The modeling identified a new regime of reaction gas flow around the FFB. In the range of FFB velocities M = 3.4-3.85, a quasi-stationary mode of shock-initiated combustion occurs. The flow parameters required for direct initiation of multifront detonation of the FFB are consistent with analytical estimates of the initiation energy.
V. M. Mochalova1, A. V. Utkin1, V. A. Sosikov1, S. I. Torunov1, D. Yu. Rapota1,2, A. V. Savchenko1, M. Yu. Shakula1,3, V. V. Vilkov1,2, S. A. Koldunov1 1Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Russia 2Lomonosov Moscow State University, Moscow, Russia 3Moscow Institute of Physics and Technology, Dolgoprudny, Russia
Keywords: detonation, critical diameter, detonation instability, nitromethane, PMMA, VISAR, high-speed camera
Optical methods for recording fast processes are applied to study a flow behind a detonation wave front in a nitromethane/polymethyl methacrylate (NM/PMMA) mixture. It is shown that, an increase in the PMMA concentration leads to an increase in the critical detonation diameter, which, as in pure NM, is determined by the occurrence of reaction failure waves at the charge-shell boundary. A NANOGATE-22/16 high-speed eight-channel sixteen-frame electron-optical camera is used not only to properly study the spatial occurrence and propagation of reaction failure waves, but also to determine their characteristic size. It is shown that unstable flow at the edge of the charge in the NM/PMMA mixture can be stabilized by adding amines or glass microspheres.
V. B. Titova, N. A. Volodina, M. O. Shirshova, P. V. Zabusov
All-Russian Scientific Research Institute of Experimental Physics, Scientific Research Institute of Experimental Physics, Sarov, Russia
Keywords: detonation kinetics, heating element, distribution channels, numerical modeling
Based on model experiments, approaches to numerical modeling of detonation wave propagation in small-section channels filled with PETN-based explosive (pentaerythritol tetranitrate) are investigated with account for macroscopic detonation kinetics.
A. A. Kotomin, A. S. Kozlov, S. A. Dushenok, P. G. Bukovskii, D. V. Barmashova
SKTB Tekhnolog, Saint Petersburg, Russia
Keywords: explosives, detonation ability, critical detonation diameter, critical detonation thickness, cylindrical charge, flat charge, charge density, charge porosity, specific surface area of explosive
This paper describes the process of obtaining homogeneous mixtures of RDX, HMX, PETN, TNT, Fox-7, and benzotrifuroxane of various dispersions with polysiloxane (SKT) as an inert soft polymer. The specific surface area of crystalline explosives (HE) varies from 440 to 4750 cm2/g, and the explosive content in the mixtures ranges from 65 to 82% (wt.). Each binary mixture (explosives/polysiloxane) yields solid, practically nonporous, flat (round ones with a diameter of 40 mm and square ones with a size of 40 × 40 mm) charges of various thicknesses and elongated cylindrical (cord) charges of various diameters. Flat and cord charges are characterized by the same composition, dispersion, density, and defectiveness of explosive crystals. Critical thicknesses and critical diameters of detonation of all mixtures are determined experimentally with an accuracy of 0.05 mm. Test conditions: flat and cord charges without shells located on a metal base. It is revealed that the ratio of the critical diameter to the critical thickness of detonation is practically constant and equal to 1.83 ± 0.1. The previously obtained dependence of the critical detonation diameter of explosives and explosive mixtures on the change porosity is also taken into account. An equation for the correct recalculation of the experimental critical detonation thickness of pressed charges of crystalline explosives with real porosity into the critical detonation diameter of high-density charges is obtained. This equation is additionally confirmed by testing many individual explosives of different dispersion and known literature data conducted in this work.
V. I. Kolesov1, E. S. Manakhova1, A. S. Gubin2, M. N. Tereshchenko2, P. S. Chernavkin2 1Mendeleev University of Chemical Technology of Russia, Moscow, Russia 2Bakhirev Research Institute of Mechanical Engineering, Moscow, Russia
Keywords: tetramethylammonium perchlorate, heat of explosion, impact sensitivity, detonation ability
This paper presents thermodynamic calculations of characteristics of explosive mixtures based on tetramethylammonium perchlorate. Their sensitivity, explosion heat, and volume are determined. The composition of gaseous explosion products is analyzed. This paper also demonstrates the possibility of creating promising explosive mixtures with detonation ability and mechanical sensitivity in the TNT-RDX range, with an explosion heat of higher than 6 MJ/kg and a hydrogen content of gaseous explosion products of more than 50% by volume.
E. A. Butenko1, I. A. Kuznetsov2, A. E. Kurepin2, L. V. Malancheva2, A. I. Malkin3, D. A. Popov3, A. A. Ryazantseva2, N. I. Shishov1, V. B. Yashin2 1Soyuz Federal Center of Dual Technologies, Dzerzhinskii, Russia 2Bakhirev State Scientific Research Institute of Mechanical Engineering, Dzerzhinsk, Russia 3Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
Keywords: explosive composition, filler, composite mixture, compatibility, blast effect, propulsive capability, brisance
This paper presents the results of a study of explosive compositions with the replacement of the combustible filler-aluminum powder-by an aluminum- and boron-containing composite mixture prepared by mechanical activation. Thermodynamic calculations of the characteristics of fillers and explosive compositions were made using the TERRA software and the NIST database. The compatibility of fillers with active binders and the influence of fillers on the detonation characteristics, blast and propulsive effects, and brisance of model explosive compositions were studied.
S. N. Buravova
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: cylindrical cumulation, instability, localization, triple shock configuration, shock wave, localized shear bands, unloading wave
Response of materials to pulse loading by cylindrical specimens is determined via two interrelated processes: shock wave motion toward the sample axis and perturbation motion in the form of triple shock configurations along the shock wave front. The surface area of the perturbed shock wave front increases due to protrusions strengthened as a result of merging with shock-wave-generated smaller perturbations. Because the front area sharply increases as the shock wave approaches the axis, several large triple shock configurations are formed and the shock wave front is divided into separate sectors in which they oscillate. The collision of powerful shock structures ensures the shock wave front motion toward the axis by removing a portion of the compressed material from the collision zone forward ahead the shock wave front and the additional compaction of the shock-compressed material by longitudinal shock structures under the wave front. The cumulation process is completed when the height of the protrusions becomes equal to the distance from the shock wave front to the axis. The near-axis space is occupied by the front protrusions, and the resulting reflected shock wave slows down the oncoming flow.
V. I. Zeldovich1, I.dag A. E. Kheifets1, I. V. Khomskaya1, D. N. Abdullina1, S. V. Balushkin2, A. Yu. Simonov2, G. V. Kulikov2 1Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia 2RFNC, Zababakhin All-Russian Research Institute of Technical Physics, Snezhinsk, Russia
Keywords: convergence of copper shells, shock-wave loading, high-speed deformation, instability of deformation front
The convergence of cylindrical copper shells subjected to explosion has been investigated. The shell surface was covered with an explosive layer. Explosion was initiated at eight points evenly spaced on a cylindrical surface. During the convergence, eight ejections were formed on the inner surface the shells; i.e., buckling of the smooth deformation front occurred. The formation of ejections is attributed to the occurrence of plastic (cumulative) jets during the interaction of adjacent shock and deformation waves. The structural mechanism of convergence of thick-walled copper shell consists of the formation, expansion, and closure of ejections. It has been found that the formation of ejections is preceded by another buckling mechanism of the deformation front-corrugation.
A. V. Babkin, A. S. Novoseltsev, S. V. Ladov
Bauman Moscow State Technical University, Moscow, Russia
Keywords: cumulation, shaped charge, liner, collapse, jet flow, dynamic deformation, surface perturbations, instability
This paper presents the results of a study of hydrodynamic instability during the collapse of shells, in particular, shaped charge liners. Initially, this instability was initiated by harmonic surface perturbations or perturbations of the load parameters. The instability manifested itself in the form of the development of these perturbations over time. The absence or limited growth of surface perturbations was considered as a manifestation of the stability of the liner deformation process. In this study, we take into account the results of both numerical simulation and available experimental data. Based on the results of the study, conclusions are formulated about the causes and possible forms of manifestation of instability during the deformation of collapsing metal liners, the governing parameters of this process, and its features and mechanism.
P. V. Zabusov, G. Ya. Karpenko, M. N. Kiryukhina, V. V. Kovaldov, A. V. Nefedov, K. N. Panov, E. V. Saprykina, M. O. Shirshova
All-Russian Scientific Research Institute of Experimental Physics, Scientific Research Institute of Experimental Physics, Institute of Experimental Gas Dynamics and Explosion Physics, Sarov, Russia
Keywords: boron carbide, ceramics, explosive experiment, X-ray, strength, failure, numerical modeling, 3D modeling
The present paper describes an X-ray experiment on explosive compression of spherical shells made of boron carbide and lead with single-point initiation of detonation on the surface of a spherical explosive layer. Experimental data are compared with numerical modeling results using the LEGAK technique. There is satisfactory agreement in the type of failure of boron carbide shells in the calculation and experiment.
S. A. Bordzilovsky, S. M. Karakhanov
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: silica, temperature, shock waves, emissivity, absorption coefficient, color temperature
The brightness and color temperatures of shock-heated fused silica were determined at thermal radiation wavelengths of ~390 to 630 nm using a four-channel pyrometer. The measurements were carried at shock compression pressures of 27.6-50.5 GPa. It is shown that the emission spectrum of shock-heated fused silica is a superposition of the thermal emission spectrum and the line spectrum. Baric dependences of the emissivity and absorption coefficient of shock-compressed fused silica were determined.
A. N. Starodubov1,2, V. I. Klishin1,2, A. N. Kadochigova1, A. V. Kaplun3 1Federal Research Center for Coal and Coal Chemistry, Siberian Branch, Russian Academy of Sciences, Kemerovo, Russia 2Gorbachev Kuzbass State Technical University, Kemerovo, Russia
Keywords: Numerical modeling, underground mining, top coal caving, arching, powered roof support, discrete element methods, arches, outlet hole
The process of rock arching in top coal caving with powered roof support systems is investigated. A direct proportional dependence between top coal flow duration and probability of static arching of rocks above an outlet hole, which prevents caving, is revealed. The new-developed method allows more accurate determination of the conditions and zones of rock arching in a model with one unit of powered roof support. When a number of powered roof support units operate in simultaneous top coal caving, the probability of arching may reduce greatly owing to the creation of a common zone of top coal flow.
M. A. Zhuravkov, M. A. Nikolaichik, I. N. Karpovich
Belarus State University, Minsk, Belarus
Keywords: Lateral oscillations, elevator hoist machine, ventilation shaft, finite volume method, mine shaft, numerical modeling, CFD
The authors focus on the numerical modeling of the dynamic behavior of elevator and counterweight with regard to airflow in a ventilation mine shaft. The finite element model of the test system is constructed. The modeling takes into account the rotation and displacements of the elevator and counterweight, as well as the elastic forces from the roller guide. The elevator and counterweight travels is studied at different stiffnesses of springs which ensure continuous contact in the roller guide-ail assembly system. The research findings are the pressure patterns in the mine shaft, the horizontal displacement field of the elevator hoist machine and the elastic forces in the roller guide springs of the elevator and counterweight.
S. A. Kondrat’ev
Chinakal Institute of Mining, Siberia Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Flotation, surface active substances, collectability, selectivity, physisorption mechanism of collectors
The mission of frothers consists in formation of fine bubbles and a frother layer of the required structure to influence floatability of minerals. The collecting and selective properties of frothers are reviewed. Based on the physisorption mechanism of reagents, a hypothesis of the collecting action of frothers in flotation is put forward. Surfactants, while reducing the time of inductance, remove the kinetic constrain of the mineral particle-gas bubble assembly formation. Collectability of surfactants is governed by their surface activity relative to the gas-liquid interface and by the density of adsorption at a mineral which is to be extracted. It is shown that frothers are effective at the gas-liquid interface rather than at the solid-liquid interface, and are not the selective collectors therefore. The high surface and flotation activities of frothers lead to the nonselective recovery of minerals in concentrates. It is proved that frothers with the low surface activity show weaker collecting properties on target minerals and on barren rocks, and, for this reason, are more selective reagents.
The aim of the study was, firsty, to consider the possibilities of applying gravity pre-concentration in a heavy media of lead-copper-zinc ore of current production. As a result of applying this method, a number of advantages can be achieved already at the stage of ore grinding and classification, namely, decrease in specific consumption scale of norms per ton of processed ore, primarily as a result of energy saving in grinding, and decrease in consumption of flotation reagents. Secondly, within the framework of economically more significant and more interesting aspect, the question of using pre-concentration for off-balance ore was considered. The potential application of the pre-concentration process can enable increasing ore reserves while flotation capacity maintaining at the current level. According to the obtained results, the quality of the pre-concentrate remains at the level of the current run-of-mine ore, and the flotation plant keeps the same capacity as it is currently.
S. P. Ostapenko, A. S. Opalev
Mining Institute, Kola Science Center, Russian Academy of Sciences, Apatity, Russia
Keywords: Iron ore, magnetite, quartz, nanoparticles in dispersion, suspension, computer model, chain model, translational diffusion coefficient, viscosity, digital transformation
For the computerization of studies aimed at improvement of processing technology of iron ore, the methodological approach is proposed to the analysis of structure and mechanical properties in suspension of magnetite nanoparticle dispersion. The approach involves the simulation modeling of motion of nanoparticle aggregates in liquid and the calibration of the model parameters using the experimental data on the viscosity dependence on the temperature and shear velocity. The structure of an aggregate of magnetite particles is analyzed, and the length and composition of a particle chain formed as a result of magnetic dipole-dipole interaction are determined. In terms of magnetite and quartz suspension, it is shown that as a consequence of internal rotation, the chain aggregate tangling takes place concurrently with the increase in the suspension viscosity in the presence of the opposite-charged particles.
V. I. Bragin1,2, A. G. Mikhailov1 1Institute of Chemistry and Chemical Technology, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, Russia 2Siberian Federal University, Krasnoyarsk, Russia
Keywords: Mass transport, humates, gold, hypergenesis, fulvic acids, solution
Natural transport of gold is a stable and permanent process in the zones of hypergenesis in gold-bearing rock masses. Dissipation and concentration of gold depend on the geochemical barrier conditions of mass transport. One of the main agents in hypergenic transformation of a substance are natural humic compounds-steadfast participants in hypergenesis. The experimental selection of a geological prototype for the hydrochemical mass transport and concentration of gold is carried out for the conditions of the mantle. The pacing factors and probable mechanism of hypergenic concentration zone formation are presented with regard to the properties of fractions of humic substances.
The authors discuss the topical problems and specifics of operation of waterworks facilities in the mining industry in the Arctic zone of Russia. The integrated technical approach is developed for the real-time remote inspection and monitoring of waterworks facilities and natural areas of preferential protection nearby mining-influence zones using advanced space and digital technologies. The mining-induced risk prediction and control is implemented through the assistance of digital twins and risk charts, with ranking of objects by the level of the adverse effects using generalized spatial data obtained in construction of 3D geo-seepage model of rock mass, geomechanical modeling of deformation and permeation processes, as well as from decoding and analysis of satellite images of industrial pollution spots in territorial water and in lowest atmospheric layer. The outcomes of 3D geo-seepage modeling at waterworks facilities are described. The effectivity of remote assessment and control over waterworks facilities and water areas with the help of the Earth remote sensing is demonstrated. The research findings on the environmental impact of induced air pollution in a mining region are discussed.