a:2:{s:4:"TEXT";s:195:"A.V. Lavrenchuk1,2, E.V. Sklyarov3,4, A.E. Izokh1,2, A.B. Kotov5, E.B. Sal’nikova5, V.S. Fedorovsky6, A.M. Mazukabzov3";s:4:"TYPE";s:4:"html";} 1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia 2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia 3Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia 4Far Eastern Federal University, ul. Sukhanova 8, Vladivostok, 690950, Russia 5Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034, Russia 6Geological Institute, Russian Academy of Sciences, Pyzhevskii per. 7, Moscow, 109017, Russia
Keywords: Mafic magmatism, isotopic age, plume-lithosphere interaction, magma source, western Baikal region
We provide new geochemical and isotope-geochronological evidence for gabbro intrusions of the Krestovsky zone in the Olkhon composite terrane. The intrusions belong to the Birkhin (~500 Ma) and Ust’-Krestovsky (~470 Ma) complexes, which underwent several pulses of magmatism. Rock structures and textures record magma crystallization in tectonically turbulent conditions. The compositions of gabbro are similar to those of subduction-related basalts, but the Ust’-Krestovsky gabbro is richer in incompatible elements than the Birkhin rocks. A similar composition trend of gabbro is observed in other areas of the Central Asian Orogenic Belt (CAOB): southeastern Tuva, Gornaya Shoria, and western Mongolia. We suggest a model of regular composition changes in parental magmas during the interaction of a mantle plume with suprasubductional lithospheric mantle.
a:2:{s:4:"TEXT";s:183:"A.E. Vernikovskaya1,2, V.A. Vernikovsky1,2, N.Yu. Matushkin1,2, P.I. Kadil’nikov1,2, I.V. Romanova1,2, A.N. Larionov3";s:4:"TYPE";s:4:"html";} 1A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia 2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia 3A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Adakites, gabbro-anorthosites, Nb-enriched metabasites, U-Th-Pb, Sm-Nd, and Rb-Sr isotope data, late Neoproterozoic, active and transform continental margin, Siberian craton, Yenisei Ridge
Based on new geostructural, mineralogical, geochemical, and isotope (Sm-Nd, Rb-Sr, and U-Th-Pb) data for igneous intrusions and metamorphic rocks of the Zimoveinyi massif, an adakite-gabbroid association has been identified for the first time in the Yenisei Ridge (southwestern framing of the Siberian craton). This study demonstrates that the adakites (quartz diorites, tonalites, and plagiogranites) and associated gabbro-anorthosites of this massif formed in the interval 576-546 Ma (U-Th-Pb zircon SHRIMP-II analysis) at the final Neoproterozoic evolution stage of the active continental margin of the Siberian craton. Our results point to a genetic relationship between the adakites and the host Nb-enriched metabasites of the Zimoveinyi massif. The studied late Neoproterozoic adakites might have formed from both crustal and mantle-crustal sources in the setting of transform strike-slip of lithospheric plates during a halt in subduction, similarly to Cenozoic igneous complexes of the transform margin in the eastern framing of Eurasia.
A.A. Sorokin1, R.O. Ovchinnikov1, N.M. Kudryashov2, A.B. Kotov3, V.P. Kovach3 1Institute of Geology and Nature Management, Far Eastern Branch of the Russian Academy of Sciences, per. Relochnyi 1, Blagoveshchensk, 675000, Russia 2Geological Institute of the Kola Scientific Center, Russian Academy of Sciences, ul. Fersmana 14, Apatity, Murmansk Region, 184200, Russia 3Institute of the Precambrian Geology and Geochronology, Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034, Russia
Keywords: Central Asian Fold Belt, Neoproterozoic, granites, Rodinia
U-Pb geochronological studies have shown at least two stages of Neoproterozoic magmatism, 940-933 and 804-789 Ma, throughout the geologic evolution of the Bureya continental massif in the east of the Central Asian Fold Belt. The first stage (940-933 Ma) was marked by the formation of the protoliths of metagabbroids and amphibole-biotite gneiss-granites of the Bureya River basin. The geochemical features of these rocks suggest that they formed, most probably, in an island-arc setting on the continental basement or on an active continental margin. The second stage (804-789 Ma) of magmatism was manifested as the formation of biotite leucogranites and hastingsite-lepidomelane granites (A-type granites) in the Chepkan River basin. The latter rocks are similar in geochemical features to within-plate granitoids. The established stages of magmatism are the most ancient for the continental massifs in the east of the Central Asian Fold Belt. It is not ruled out that these magmatism stages were related to the stages of formation and breakup of the Rodinia supercontinent.
a:2:{s:4:"TEXT";s:54:"S.I. Shkol’nik1, V.A. Makrygina2";s:4:"TYPE";s:4:"html";} 1Institute of the Earth's Crust, Siberian Branch of the Russian Academy of Sciences, ul. Lermontova 128, Irkutsk, 664033, Russia 2Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, 664033, Irkutsk, Russia
Keywords: Kornilova and Shubutui Formations, major- and trace-element compositions, Sm-Nd isotope systematics, provenance, tectonic setting, Khamar-Daban terrane
Subsection: PETROLOGY, GEOCHEMISTRY, AND MINERALOGY
New data have been obtained on major- and trace-element compositions and Sm-Nd isotope systematics of clastic metasediments that belong to the Kornilova and Shubutui Formations in the Khamar-Daban terrane. The Kornilova Formation flysch derived from felsic mature crust, while the Shubutui Formation, with 4.5-7.5 wt.% MgO and higher Cr and Ni contents, had a mafic-ultramafic protolith of an island-arc setting. Isotope data indicate significant inputs of Precambrian crustal material (εNd( T ) = -10 to -6.2) to the protolith of the Kornilova rocks and of high amounts of synsedimentary juvenile material to the protolith of the Shubutui Formation (εNd( T ) = -2.9 to -1.5). Different model ages (1.7-2.0 and 1.3-1.4 Ga, respectively), compositions, and provenances of the Kornilova and Shubutui rocks, as well as a prolonged deposition gap (>100 Myr), evidence that the two formations were deposited in different basins and tectonic settings. The rock compositions and Nd isotope signatures suggest an island arc setting for the Shubutui deposition in the Dzhida terrane and a continental-margin setting for the deposition of the Kornilova Formation, which is the uppermost straton of the Khamar-Daban terrane.
a:2:{s:4:"TEXT";s:87:"O.L. Gas’kova1,2, V.D. Strakhovenko1,2, E.A. Ovdina1,2";s:4:"TYPE";s:4:"html";} 1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia 2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
Keywords: Saline lakes, bottom sediments, thermodynamic modeling, Kulunda steppe
Subsection: PETROLOGY, GEOCHEMISTRY, AND MINERALOGY
The diversity of the chemical composition of water in lakes, even those located at a few hundred meters from each other, has long attracted the attention of researchers. Detailed hydrochemical testing of two small soda lakes in the Kulunda steppe, located at 14 km from each other, provided answers to many questions. Although the lakes have pH > 9 and thus are assigned to the soda type, they differ in the composition of saline waters (HCO3-Cl-Na and Cl-SO4-Na-Mg) and bottom sediments. The indicator minerals in the sediments of the lake near Severka Village are pyrite, disordered Ca-smectites, and dolomite (the latter is strongly predominant, especially in the lower part of the sediment section). The minerals in the bottom sediments of the other lake are dominated by terrigenous quartz, feldspars, excess-Ca dolomite, and Mg-calcite, with the portion of carbonates increasing in the lower part of the section. Based on the reported facts, the assumption is made that the landscape position, the influence of groundwaters, and technogenic factors (land plowing) are the main reason for the differences between the two lake systems. The task is set to study biocoenoses and their effect on the diagenesis of bottom sediments.
V.I. Kosyakov1, E.F. Sinyakova2 1A.V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrent'eva 3, Novosibirsk, 630090, Russia 2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Cu-Fe-Ni-S system, phase equilibria, zoning, fractional crystallization, pentlandite
Subsection: PETROLOGY, GEOCHEMISTRY, AND MINERALOGY
For experimental modeling of the formation of pentlandite-bornite ore during fractional solidification of sulfide magma, we performed directional quasi-equilibrium crystallization of a melt containing (mol. %) 17.19 Cu, 19.05 Fe, 19.66 Ni, and 44.10 S, from which pentlandite and bornite can cocrystallize. Based on the results of measurement of the average composition of the solid phase, the distribution curves of the components in the ingot were constructed and the change in the melt composition during directional solidification was calculated. The obtained data show that the crystallized sample consists of six zones, each of which has characteristic phase and chemical compositions. In the Cu-Fe-Ni-S composition tetrahedron, the melt composition path is a broken spatial curve, each segment of which corresponds to a point showing the average composition of one of the zones. These points form a disordered set, indicating a complex fractionation process. Investigations of characteristic microstructures along the ingot, using data on its average chemical composition, made it possible to determine the probable set of primary phases crystallizing from the melt (bornite solid solution bnss, three types of pentlandite with different cation compositions: cfpn, npn, and cnpn, and quaternary solid solution tss) and to establish the sequence of separation of these phases and their associations from the melt in six zones: cfpn (zone I) / cfpn + bnss (zone II) / cfpn + bnss + npn (zone III) / tss + bnss (zone IV) / cnpn + bnss (zone V) / npn + bnss (zone VI). A scheme of phase reactions along the crystallization path has been compiled, and it has been shown that high-temperature pentlandite forms have a significant effect on the fractionation process. These results are consistent with previous data on the fractional crystallization of multicomponent sulfide melts and the theoretical features of this process. In previous studies, samples with a small number of zones were obtained. In this study we first obtained a sample containing six zones. The zoning observed in the sample belongs to the complex second type of low-sulfur zoning of orebodies. The same data confirm the possibility of different types of zoning within the major two types of zoning of copper-nickel orebodies.
A. K. Khe1,2, A. A. Cherevko1,2, A. P. Chupakhin1,2, A. L. Krivoshapkin3, K. Yu. Orlov3, V. A. Panarin4
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:333:"1Lavrent’ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk, Russia 2Novosibirsk State University, 630090 Novosibirsk, Russia 3Meshalkin National Medical Research Center, 630055 Novosibirsk, Russia 4Medical Center, 690920 Ayaks, Russia";}
Keywords: гемодинамика головного мозга, интраоперационный мониторинг, скорость и давление в сосудах головного мозга, удельная нагрузка, предельная эмболизация, brain hemodynamics, intraoperative monitoring, velocity and pressure in brain vessels, specific load, limiting embolization
This paper describes the results of intraoperational monitoring of hemodynamic parameters (velocity and pressure) in brain vessels, carried out within the framework of 50 neurosurgical operations using a Volcano ComboMap instrumental measuring system. It is established that the introduced parameter of specific load used during the neurosurgical operations is a significant parameter for the success of the operation.
V. V. Penenko, A. V. Penenko, E. A. Tsvetova
Institute of Computational Mathematics and Mathematical Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: математическое моделирование, модели гидродинамики и химии атмосферы, вариационный принцип, усвоение данных наблюдений, Новосибирская агломерация, mathematical modeling, model of hydrodynamics and chemistry of the atmospheric, variational principle, assimilation of observational data, Novosibirsk agglomeration
This paper presents a variational approach to the solution of direct and inverse problems based on the joint use of mathematical models and monitoring data for processes of geophysical hydrothermodynamics. This approach is used to solve problems related to environmental protection. A variational principle with weak restrictions is formulated to account for uncertainties and errors in models and data. Inclusion of uncertainties makes it possible to construct direct non-iterative algorithms for sequential assimilation of data obtained by various observational systems. Criteria and functions for controlling the quality of the natural environment are introduced into the modeling system to solve inverse problems of environmental safety. The problem with data assimilation for the Novosibirsk agglomeration is considered.
S. F. Garanin, A. M. Buiko, V. B. Yakubov
All-Russia Research Institute of Experimental Physics, Sarov, 607188 Russia
Keywords: имплозия лайнеров, z-пинч, неустойчивость Рэлея - Тейлора, аспектное отношение, численные решения двумерных задач магнитной гидродинамики, implosion of liners, z-pinch, Rayleigh-Taylor instability, aspect ratio, numerical solutions of two-dimensional problems of magnetic hydrodynamics
A review of publications on the Rayleigh-Taylor instability arising due to high-velocity implosion of liners is presented. Papers that describe experimental testing and numerical simulation of the development and suppression of this instability are also considered.
S. V. Meleshko1, A. G. Petrova2, V. V. Pukhnachev3,4 1Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand 2Altai State University, Barnaul, 656049 Russia 3Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 4Novosibirsk State University, Novosibirsk, 630090 Russia
Keywords: несжимаемая вязкоупругая среда Максвелла, объективная производная, характеристики, линейная модель, incompressible viscoelastic Maxwell medium, objective derivative, characteristics, linear model
Characteristics of a system of equations that describe three-dimensional motion of an incompressible viscoelastic Maxwell medium with the upper and lower convective derivatives and the rotational Jaumann derivative being used in the rheological relation are calculated. An initial-boundary-value problem is formulated for the system linearized in the vicinity of the quiescent state, and its unique solvability is established.
V. M. Kovenya, P. V. Babintsev
Institute of Computational Technologies, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: уравнения Эйлера и Навье - Стокса, конечно-объемные схемы, сверхзвуковые течения, отрывы, скачки уплотнения, Euler and Navier-Stokes equations, finite-dimensional schemes, supersonic flows, separations, shock waves
For the numerical simulation of aerodynamics problems, the Euler and Navier-Stokes equations written in integral form are used to construct an implicit finite-dimensional predictor-corrector scheme. At the predictor stage, the splitting of equations into physical processes and spatial directions is introduced, which makes it possible to reduce the solution of the original system to the solution of individual equations on fractional steps by the scalar sweep method and ensure the stability of the algorithm as a whole. The paper also describes the supersonic gas flows in a narrowing channel with regular and non-regular reflection of the compression shock from the symmetry plane and the numerical substantiation of the existence of pulsating flow with a supersonic flow past a cylinder with a needle.
V. Yu. Lyapidevskii1,2, V. V. Novotryasov3,4, F. F. Khrapchenkov3, I. O. Yaroshchuk3
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:408:"1Lavrent’ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Novosibirsk State University, Novosibirsk, 630090 Russia 3V. I. Il’ichev Pacific Oceanological Institute, Far-Eastern Branch, Russian Academy of Sciences, Vladivostok, 690041 Russia 4Far Eastern Federal University, Vladivostok, 690041 Russia";}
Keywords: стратифицированные течения, уединенные волны, внутренний бор, трехслойная мелкая вода, шельфовая зона, stratified flows, solitary waves, internal boron, three-layer shallow water, shelf zone
This paper presents the observation results for the internal wave boron in the coastal region of the Sea of Japan with the use of vertical thermistor chains. The data obtained is interpreted by the mathematical models of shallow water in which the effect of nonlinearity and variance on the propagation of internal wave packages is taken into account. Within the framework of the theory of multilayer shallow water, the problem of transformation of a solitary wave into an internal boron is solved, and the possibility of recovery of a space-time picture of the flow during the passage of an internal boron in the section between adjacent experimental bottom stations is demonstrated.
N. I. Yavorskii1,2 1Novosibirsk State University, Novosibirsk, 630090 Russia 2Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: магнитогидродинамическое течение, вязкая несжимаемая жидкость, бифуркация вращения, класс Кармана, magnetohydrodynamic flow, viscous incompressible fluid, rotation bifurcation, Karman class
Magnetohydrodynamic (MHD) flow of a viscous electroconductive incompressible fluid between two stationary impermeable disks is considered. A homogeneous electric current density vector along the normal to the surface is specified on the upper disk, and the lower disk is non-conductive. The exact von Karman solution of the complete system of MHD equations is studied in which the axial velocity and the magnetic field depend only on the axial coordinate. The problem contains two dimensionless parameter: the electric current density on the upper plate Y and the Batchelor number (the magnetic Prandtl number). It is assumed that the external source producing the axial magnetic field is absent. The problem is solved for the Batchelor number in the range of 0-2. Fluid flow is produced by electric current. It is shown that for small values of Y , the fluid velocity vector of the has only axial and radial components. The rate of motion increases with increasing Y , and at a critical value of Y , there is a bifurcation of a new stable flow regime with fluid rotation, while the flow without rotation becomes unstable. A feature of the obtained new exact solution is the absence of an axial magnetic field necessary for the occurrence of an azimuthal component of the ponderomotive force, as is the case in the MHD dynamo. A new mechanism of the bifurcation of rotation in the MHD flow is found.
D. V. Khotyanovsky, A. N. Kudryavtsev
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: прямое численное моделирование, ламинарно-турбулентный переход, сверхзвуковой пограничный слой, распределенная шероховатость, direct numerical simulation, laminar-turbulent transition, supersonic boundary layer, distributed roughness
Direct numerical simulations of instability development and transition to turbulence in a supersonic boundary layer on a flat plate are performed. The computations are carried out for moderate supersonic (free-stream Mach number M = 2) and hypersonic (M = 6) velocities. The boundary layer development is simulated, which includes the stages of linear growth of disturbances, their nonlinear interaction, stochastization, and turbulent flow formation. A laminar-turbulent transition initiated by distributed roughness of the plate surface at the Mach number M=2 is considered.
E. S. Bolshakova1, V. K. Kedrinskii2 1Novosibirsk State University, Novosibirsk, 630090 Russia 2Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: ударная волна, кавитационный процесс, слой жидкости, разрыв, масштабный фактор, shock wave, cavitation process, liquid layer, discontinuity, scale factor
The problem of experimental modeling of discontinuity formation in a cavitating liquid layer under shock wave loading is considered. It is shown that the discontinuity takes the shape of a sphere segment and retains it up to the closure instant. The discontinuity surface becomes covered with a dynamically growing thin boundary layer consisting of bubbles, which transforms to a ring-shaped vortex bubble cluster at the instant of closure of the discontinuity emitting a secondary shock wave. Specific features of the structure of the cavitating flow discontinuity arising at loading intensities lower than 0.1 and 5 kJ are discussed.
P. A. Polivanov, Yu. V. Gromyko, A. A. Sidorenko, A. A. Maslov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: пограничный слой, гиперзвуковые скорости, ламинарно-турбулентный переход, шероховатость, энтропийный слой, boundary layer, hypersonic velocity, laminar-turbulent transition, roughness, entropy layer
The influence of a cylinder-shaped single roughness element on the laminar-turbulent transition in the presence of an entropy layer is experimentally studied. The experiments are performed on a blunted cone mode at the Mach number M=5. The roughness element is located on the blunted tip of the model. Information about the mean and fluctuating parameters of the boundary layer in the wake behind the roughness element is obtained by using hot-wire anemometry. It is shown that flow turbulization behind the roughness elements occurs at the local Reynolds number calculated on the basis of the roughness element height and equal to 400-500. It is found that the presence of the roughness element exerts a significant effect on the unsteady characteristics of the boundary layer if the roughness element height is smaller than the effective value.
E. A. Bondarev, I. I. Rozhin, K. K. Argunova
Institute of Oil and Gas Problems, Siberian Branch, Russian Academy of Sciences, Yakutsk, 677980 Russia
Keywords: сопряженные задачи теплообмена, добыча и транспортировка природного газа, гидраты природного газа, related heat transfer problems, natural gas production and transportation, natural gas hydrates
The existing algorithm for determining mass flow in gas production and transportation systems from output pressure measurements is extended to the case where the internal section of the tube changes with time and is also to be determined in the course of solving the general problem. It is proposed to use this algorithm to determine the presence of hydrates in such systems. An example of determining the presence of hydrates in a main gas pipeline section in permafrost is considered.
V. Sh. Shagapov1,2, Z. M. Nagaeva3 1Institute of Mechanics and Engineering, Kazan Scientific Center, Russian Academy of Sciences, Kazan 420111, Russia 2Mavlyutov Institute of Mechanics, Ufa Scientific Center, Russian Academy of Sciences, Ufa, 450054 Russia 3Ufa State Oil Technical University, Ufa 450062, Russia
Keywords: гидроразрыв пласта, трещина, волны давления, интегродифференциальное уравнение, дисперсионный анализ, fracturing, crack, pressure waves, integrodifferential equation, variance analysis
Pressure filtration waves in cracks in porous permeable medium are studied. The effect of the porosity and permeability of the formation and crack, the crack width, and the rheological properties of the saturating fluid on the dynamics of perturbations in the crack are studied. It is shown that in a porous permeable formation, a crack is a wave channel through which low-frequency pressure fluctuations in wells propagate. Accurate solutions are obtained which describe the evolution of pressure fields in a crack with an instantaneous pressure change in the well by a constant value. Based on these solutions, the corresponding dependences of the fluid flow on time and the pressure at the boundaries are determined.
S. V. Stankevich1,2, G. A. Shvetsov1,2, V. G. Butov3, S. V. Sinyaev3 1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Novosibirsk State Technical University, Novosibirsk, 630073 Russia 3Institute of Applied Mathematics and Mechanics, National Research Tomsk State University, Tomsk, 634050 Russia
Keywords: многорельсовый электромагнитный ускоритель, нагрев рельсов, численное моделирование, импульсный магнитогидродинамический генератор, multi-rail electromagnetic accelerator, heating of the rails, numerical simulation, pulsed magnetohydrodynamic generator
The operation of rapid-fire multi-rail electromagnetic launchers of solids in a burst mode is analyzed by numerical modeling in two-dimensional and three-dimensional nonstationary formulations. In the calculations, the launchers are powered from a Sakhalin pulsed magnetohydrodynamic generator. Launchers with three and five pairs of parallel rails connected in a series electrical circuit are considered. Bursts of different numbers of solids having different weight are modeled. It is established that the heating of rails is one of the main factors limiting the performance of launchers under such conditions is. It is shown, that the rate of heating of the rails is determined by the inhomogeneity of the current density distribution over the rail cross-section due to the nonstationary diffusion of the magnetic field into the rails. Calculations taking into account the nonstationary nature of the current density distribution in the rails of a multi-rail launcher have shown that a proper choice of the weight of the accelerated solids (up to 800 g), their number in the burst, and the material of the rails makes it possible to attain launching velocities of 1.8-2.5 km/s at moderate heating of the rails.
A. K. Rebrov, A. A. Emel'yanov, M. Yu. Plotnikov, I. B. Yudin
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: алмазные структуры, газоструйное осаждение, термическая активация, прямое статистическое моделирование, diamond structures, gas jet deposition, thermal activation, Direct Simulation Monte Carlo method
The flow of a hydrogen-methane mixture through heated coaxial cylindrical tungsten channels with a built-in tungsten wire is studied by the Direct Simulation Monte Carlo method. The purpose of the study is further development of the gas-phase method of deposition of diamond structures. The axial distributions of the concentrations of the components of the hydrogen-carbon mixture are calculated by means of solving a system of chemical kinetics equations. A series of experiments on deposition of diamond structures from various flows of the hydrogen-methane mixture is performed. The calculated results are compared with the experimental data. Based on these comparisons, it is concluded that numerical optimization of operation modes of gas-dynamic reactors can be used for deposition of diamond structures.
R. S. Volkov1, G. V. Kuznetsov1, V. E. Nakoryakov2, P. A. Strizhak1 1National Research Tomsk Polytechnic University, Tomsk, 634050 Russia 2Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: капля воды, высокотемпературные газы, испарение, скорость испарения, water droplet, high-temperature gases, evaporation, evaporation rate
Evaporation rates of water droplets in high-temperature gases were experimentally determined using high-speed video recording cameras and low-inertia thermocouples (for heated air flow as an example). The experiments were carried out for droplets of initial size (radius) of 1-3 mm at an air temperature 500-1000 K. Dependences of the evaporation rate of water droplets on time and gas temperature for various initial droplet sizes were obtained.
S. P. Kiselev1,2, V. P. Kiselev1 1Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Novosibirsk State Technical University, Novosibirsk, 630092 Russia
Keywords: интерметаллид титан - алюминий, уравнение диффузии, метод молекулярной динамики, расплав алюминия, кристалл титана, Titanium-aluminum intermetallic compound, diffusion equation, molecular dynamics method, aluminum melt, titanium crystal
Titanium dissolution in the aluminum melt and synthesis of an intermetallic compound at constant temperature and pressure are numerically simulated by the molecular dynamics method. Owing to titanium dissolution, the TiAl3 intermetallic compound is formed near the interface between the titanium crystal and aluminum melt. Based on the theory of weak solutions, a mathematical model of titanium dissolution in the aluminum melt is constructed. Dependences of the diffusion coefficient, equilibrium concentration of titanium, and dissolution rate on temperature are obtained.
Yu. M. Volchkov1,2
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:195:"1Lavrent’ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Novosibirsk State University, Novosibirsk, 630090 Russia";}
Keywords: уравнения изгиба слоистых пластин, ортотропный материал, полиномы Лежандра, bending equations for laminated plates, orthotropic material, Legendre polynomial
This paper describes the modified bending equations of layered orthotropic plates in the first approximation. The approximation of the solution of the equation of the three-dimensional theory of elasticity by the Legendre polynomial segments is used to obtain differential equations of the elastic layer. For the approximation of equilibrium equations and boundary conditions of three-dimensional theory of elasticity, several approximations of each desired function (stresses and displacements). The stresses at the internal points of the plate are determined from the defining equations for the orthotropic material, averaged with respect to the plate thickness. The construction of the bending equations of laminated plates for each layer is carried out with the help of the elastic layer equations and the conjugation conditions on the boundaries between layers, which are conditions for the continuity of normal stresses and displacements. The numerical solution of the problem of bending of the rectangular laminated plate obtained with the help of modified equations is compared with an analytical solution. It is determined that the maximum error in determining the stresses does not exceed 3%.
E. I. Romenskii1,2, E. B. Lys3, V. A. Cheverda3, M. I. Epov3 1Sobolev Institute of Mathematics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Novosibirsk State University, Novosibirsk, 630090 Russia 3Trofimuk Institute of Oil and Gas Geology and Geophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: движение упругой среды, начальные напряжения, упругие волны, motion of an elastic medium, initial stresses, elastic waves
The constitutive equations of motion of an elastic medium with given initial stresses are formulated in the form of a hyperbolic system of differential equations of the first order. Equations describing the propagation of small perturbations in a prestressed isotropic medium with an arbitrary energy dependence of the elastic deformation in the strain tensor are derived, and equations for the quadratic dependence of elastic strain energy on the strain tensor are given.
K. G. Okhotkin1,2, A. Yu. Vlasov3, Yu. V. Zakharov3, B. D. Annin4 1Reshetnev Information Satellite Systems, Zheleznogorsk, 662972 Russia 2Krasnoyarsk Scientific Center, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036 Russia 3Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, 660014 Russia 4Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: гибкая пластина, геометрическая нелинейность, рефлектор антенны, композиционный материал, flexible plate, geometric nonlinearity, antenna reflector, composite material
This paper presents of an geometrically nonlinear analytical model of a flexible cylindrical frame (rim) of the transformable precision large-size reflector of space antennas made using polymer composite materials with form memory. A nonlinear boundary-value problem for the frame in a deformed (collapsed) state is formulated and exact analytic solutions in elliptic functions and integrals which describe the deformation modes of the rim. A geometrically nonlinear model us used to obtain exact analytical solutions which allow preliminary determination of the geometric dimensions and the optimal shape of the flexible frame and estimate the stored energy.
E. N. Sher
Chinakala Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630091 Russia
Keywords: взрыв, скважинные заряды, шпуровые заряды, радиальные трещины, форма трещин, трехмерное моделирование, explosion, borehole charges, blasthole charges, radial crack, crack shape, three-dimensional modeling
Numerical schemes for determining the shape and dimensions of radial cracks formed during confined explosions of linear charges located in a monolithic rock massif at a great depth and near its surface. The influence of the charge length on the dimensions of radial cracks in a confined explosion is studied. The amount of undercharging of a borehole or blast charge for which the area radial cracks is maximal is determined.
B. D. Annin1, V. M. Fomin2, E. V. Karpov1, A. G. Malikov2, A. M. Orishich2 1Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia 2Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: лазерная сварка, алюминиевые сплавы, термообработка, пластическая деформация, прочность, микроструктура, фазовый состав, laser welding, aluminum alloys, thermal treatment, plastic strain, strength, microstructure, phase composition
Results of experimental investigations of welded joints of high-strength aluminum-lithium alloys of the Al-Cu-Li and Al-Mg-Li systems are reported. The welded joints are obtained by means of laser welding and are subjected to various types of processing for obtaining high-strength welded joints. A microstructural analysis is performed. The phase composition and mechanical properties of the welded joints before and after thermal treatment are studied. It is found that combined thermal treatment of the welded joint (annealing, quenching, and artificial aging) increases the joint strength, but appreciably decreases the alloy strength outside the region thermally affected by the welding process.
V. M. Fomin, A. A. Golyshev, V. F. Kosarev, A. G. Malikov, A. M. Orishich, N. S. Ryashin, A. A. Filippov, V. S. Shikalov
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: карбид бора, никель, покрытие, холодное газодинамическое напыление, лазерное воздействие, микроструктура, шероховатость, морфология, boron carbide, nickel, coating, cold gas-dynamic spraying, laser action, microstructure, roughness, morphology
A method is proposed for creating principally new functionally graded heterogeneous materials on the basis of B4C ceramic powders with different mass fractions in the initial mixture and plastic metallic additive of Ni by a combined method of cold gas-dynamic spraying with a subsequent layer-by-layer laser action. Mechanical properties of the resultant tracks are examined. It is shown that the track microhardness increases with increasing B4C concentration in the initial mixture. The track structure is found to depend on the size of ceramic particles in the interval from 3 to 75 μm. Reduction of the B4C particle size (approximately by a factor of 2-3) inside the track owing to fragmentation under the action of the laser beam is observed for the first time.
At full and over load operating points, some Francis turbines experience
strong self-excited pressure and power oscillations. These oscillations are occuring due to the hydrodynamic instability of the cavitating
fluid flow. In many cases, the amplitude of such pulsations may be reduced
substantially during the turbine operation by the air injection/admission below
the runner. Such an effect is investigated numerically in the present work. To
this end, the hybrid one-three-dimensional model of the flow of the mixture
“liquid-vapor” in the duct of a hydroelectric power station, which was proposed
previously by the present authors, is augmented by the second gaseous component
¾ the non-condensable air. The boundary conditions and the numerical
method for solving the equations of the model are described. To check the
accuracy of computing the interface “liquid-gas”, the numerical
method was applied at first for solving the dam break problem. The algorithm
was then used for modeling the flow in a hydraulic turbine with air injection
below the runner. It is shown that with increasing flow rate of the injected
air, the amplitude of pressure pulsations decreases. The mechanism of the flow
structure alteration in the draft tube cone has been elucidated, which leads to
flow stabilization at air injection.
An explicit algebraic
model of Reynolds stresses and the turbulent heat flux vector for the planetary
boundary layer in a neutrally stratified boundary layer of the atmosphere above
a homogeneous rough surface is tested. The version of the algebraic model
under consideration is constructed on the physical principles of the RANS (Reynolds-averaged Navier-Stokes)
approximation for describing stratified turbulence, it employs three forecasting equations, and a correct reproduction of the main characteristics of a neutral
atmospheric boundary layer ¾ the components of the mean wind velocity, the wind turn angle, and the turbulent statistics is shown. Test computations show that the proposed model may be used for
goal-oriented investigations of the atmospheric boundary layer.
In the present paper, we
report on the results of an experimental study of the process of gravity
sedimentation of a cloud of monodispersed solid spherical particles with
initial volume concentration C >
0.03, which was performed in a wide range of Reynolds numbers. An
analytical estimate of the settling regimes of spherical particle clouds is presented.
A new method for creating a spherical particle cloud with a high concentration
of particles is proposed. A qualitative picture of the settling process of
a highly concentrated particle cloud under gravity is revealed. A criterial
dependence for the drag coefficient of a sedimenting spherical particle cloud
as an entity is obtained.
Results of a film
cooling numerical simulation over a flat plate with coolant supply into
indentations of different shape are reported. The calculations were performed for the blowing-ratio changed from 0.5
to 2.0. For comparison, data for traditional film cooling scheme with one row
of discrete cylindrical inclined holes were used. At small value of blowing ratio (m = 0.5), the average film-cooling efficiency is roughly
identical for all indentations tested. With blowing ratio growth, the scheme
with a coolant supply into the transverse trench demonstrates the best results.
The conditions of
formation of a three-dimensional thermocapillary structure on the surface of a
liquid film flowing along a heater with the constant temperature were studied
numerically based on the derived system of equations. Formation of the
thermocapillary structure was modeled by periodic perturbations in the
transverse direction superimposed on the two-dimensional flow. It is shown in
calculations that transversal perturbations can develop into periodic rivulet
structures on the film surface if the Marangoni number exceeds some threshold
value. It is revealed that the rivulet structure develops when the period
belongs to a certain range, which is determined by the value of Marangoni
number. The results of calculations are in a good agreement with experimental
data.
An evaporation of
kerosene and water was investigated based on convective heat transfer in the
experimental setup simulating a typical volume of the fuel tank of the launch
vehicle. Basic criteria of similarity used in choosing the design parameters of
the setup, parameters of the coolant and model liquids, were numbers of
Reynolds, Prandtl, Biot, and Nusselt. The used coolants were gases, including
air and nitrogen; in addition, at the stage of preliminary experiments,
products of combustion of hydroxyl-terminated polybutadiene (HTPB) were
considered. Boundary conditions were taken for the liquid located on the plate
in the form of "drop" and at its uniform film spread in the experimental
model setup. On the basis of experimental investigations, the temperature
values were obtained for the system "gas-liquid-wall", and areas of
mass transfer surface and heat transfer coefficients of “gas-liquid” and “gas-
plate” were determined for coolants (air and nitrogen) and for liquids (water
and kerosene). The comparative analysis of the obtained results and the known
data was carried out. Proposals for experiments using coolants based on HTPB
combustion products have been formulated.
This study presents
dual-temperature two-phase model for liquid-vapor mixture with account for
evaporation and inter-phase heat transfer (taken in single-velocity
single-pressure approximation). Simulation was performed using the
shock-capturing method and moving Lagrangian grids. Analysis was performed for
simulated and experimental values of nucleation frequency (for refining the
initial number and radius of microbubbles) which affect the evaporation rate.
Validity of 2D and 1D simulation was examined through comparison with
experimental data. The peculiarities of the water-steam formation at the
initial stage of outflow through a thin nozzle were studied for different initial equilibrium states of water for the
conditions close to chosen experimental conditions.
Interdiffusion in
lithium-lead melts containing 10.0, 15.0, 18.1, 20.0, 25.1, 30.2, 38.2, 40.1,
43.1, 46.7, 50.2, 60.2, and 70.0 at. % Pb was investigated using gamma-ray
attenuation technique in the temperature range from 720 to 1030 K. It has
been found that the concentration dependence of the interdiffusion coefficient
has a maximum in the vicinity of 20 at. % Pb. This phenomenon is
shown to relate to a tendency of formation of short-range order in liquid
alloys of lithium-lead.
Numerical evaluation of
the laser-pulse modification of a metal layer with refractory nano-size
particles was done. The modes of the laser-pulse action promoting creation of
the flows for homogeneous distribution of modifying particles in the melt were
determined for various amounts of the surface-active admixture in the metal.
The paper describes
the developed method for analyzing technological schemes of thermal power
plants based on solving problems of auxiliary linear programming. This method
involves solving the linear programming problems to evaluate the effect of
supply and removal of heat or material flows of various sizes at different
points of the technological scheme of a thermal power plant (TPP). The method
effectiveness is demonstrated by the example of the coal-dust steam turbine
unit with nominal electrical output of 660 MW. As a result of its application,
the change of the technological scheme of the unit was found to provide
reduction in electricity cost by 0.3%.
Simulation
is presented for the case of water coolant outflow with initial supercritical
parameters after high pressure pipeline breaking. The nonequilibrium relaxation
model of phase transition was developed and validated. The model describes
both boiling and condensation processes.
The evaporating water droplets on a horizontal heated substrate were experimentally studied. The constantan foil 25 μm thick with a size of 42x35 mm2 was used as a substrate. The
experiments were carried out with a single droplet or with an ensemble of two
or three droplets on the foil. The temperature of the lower surface of foil
was measured by an IR scanner. To determine the heat flux density at
evaporation of liquid near the contact line, the Cauchy problem for the
heat conduction equation was solved using the thermographic data. The results
of calculations showed that the maximal heat flux density takes place in the
region of the contact line and exceeds the average heat flux density from the
entire surface of foil. This is explained by the heat inflow from the foil
periphery to the droplet due to relatively high value of the coefficient
of heat conductivity of the foil material and high evaporation intensity in the
contact line region.
