V.V. Marusin1,2 1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: Vendian, Cambrian, General Stratigraphic Scale of Russia, International Chronostratigraphic Chart, small shelly fossils, trace fossils, chemostratigraphy, Siberian Platform
Nemakit-Daldynian Stage was originally introduced as a regional stage, embracing the lowermost Cambrian strata with the oldest small shelly fossils, for the Anabar uplift sections in the 1960s. In subsequent years, it became widespread in the works of Soviet researchers as the terminal stage of the Upper Vendian series. Almost at the same time, the concept of the Manykaian stage appeared, which is close in its volume and geological meaning to the Nemakit-Daldynian Stage. Although this unit plays a crucial role for our understanding of the chronology of biotic turnovers at the Vendian-Cambrian transition, its status, age, and correlation with the Manykaian stage and units of the International Chronostratigraphic Chart (ICC) remain unclear. This study reveals the development of concepts regarding the stratigraphic volume and rank of the Nemakit-Daldynian Stage. The integrated biostratigraphic, stable isotope and geochronological data shows this unit belongs to the Upper Vendian series and spans the interval from the first appearance of unequivocal anabaritids (~539 Ma) to the first appearance of the Tommotian small shelly fossils (~530 Ma). In this interpretation, the Nemakit-Daldynian Stage corresponds to the Fortunian stage of the Cambrian System in the ICC. The base of this unit is coeval to the base of the Rovno regional stage of Baltica.
N.K. Lebedeva
Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Dinoflagellate cysts, Campanian, biogeography, paleogeography, correlation
Results of an analysis of the geographical distribution and taxonomic diversity of dinoflagellate cysts in the Campanian age of the Northern Hemisphere are presented. Three types of dinocyst assemblages are established on the basis of the qualitative and quantitative assessment of their generic composition. Some stratigraphically important genera and species, previously having narrower habitats, have been widely distributed due to transgressive events, expansion of interbasin connections, and the presence of multidirectional meridional currents. This study reveals the possibility of comparing the North Siberian dinocyst assemblages with those from the stratotypes containing the orthostratigraphic faunal groups of the West European and North American Campanian deposits through the ecotone sections of the Subpolar Cis-Urals and the south of Western Siberia.
V.B. Bazarova1, M.A. Klimin2, M.S. Lyashchevskaya1, E.N. Zakharchenko2, T.R. Makarova1 1Pacific Geographical Institute, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, Russia 2Institute of Water and Environmental Problems, Far Eastern Branch of the Russian Academy of Sciences, Khabarovsk, Russia
Keywords: Peat deposits, botanical composition, diatoms, spores and pollen, photosynthetic pigments, peat ash content, humidity index, radiocarbon dating, Far East of Russia
A continuous record of paleogeographic events of the Holocene has been reconstructed based on biostratigraphic study and radiocarbon dating of the coastal peat bog in Nerpichy Bay, the Sea of Okhotsk. Development of zonal landscapes since the end of the late Pleistocene began from shrub forest-tundra to birch elfin forest with the first appearance of broadleaved trees in the early Holocene (about 10 cal ka BP), dominance of dark coniferous taiga with maximum participation of broadleaved trees in the middle Holocene, their further decrease in the late Holocene and almost complete disappearance at present. On the coast peat began to accumulate when temperature increased, about 10.2 cal ka BP. A rapid change of the swampy larch forest, after large-scale fires, to a community dominated by true mosses, and then to subshrub-grass-sphagnum phytocenoses was a peculiar feature of the bog ecosystem evolution. Further successions occurred with a gradual replacement of eutrophic-mesotrophic sphagnum mosses by oligotrophic Sphagnum fuscum ; for the latter the highest rates of peat accumulation were noted to be at 7.2-6.1 cal ka BP. At that time the average annual temperature was approximately 2 °C higher than the present, and the long-term average annual precipitation was approximately 40 mm higher than at present. The most pronounced cooling periods in the Holocene occurred at 10.6-10.2, 9.2-8.9, 8.3-8.0, 5.2-4.8, 4.3-4.0, 3.5-3.3, 2.8-2.5, 1.5-1.0 and 0.6-0.4 cal ka BP. The cooling events identified in the southwestern coast of the Sea of Okhotsk are consistent with the sequence of cold events of the Holocene both in the region and in the Northern Hemisphere.
S.V. Borzenko, I.A. Komogortseva
Institute of Natural Resources, Ecology and Cryology, Siberian Branch of the Russian Academy of Sciences, Chita, Russia
Keywords: Lakes, sulfates, sulfate reduction, evaporation, water-rock interaction
We analyzed the mineral and chemical compositions of water and bottom sediments of lakes as well as the isotopic compositions of carbon and oxygen in dissolved and precipitated carbonates and of elemental, sulfate, and hydrogen sulfide sulfur. It has been established that the groundwater and surface waters feeding saline sulfate lakes belong to the sulfate-hydrocarbonate or hydrocarbonate-sulfate types with pH < 9 The research shows predominantly soda and sulfate lakes in the study region. It has been revealed that the sulfate coefficient of the water in such lakes exceeds 1 and that it decreases with increasing salinity as a result of the precipitation of thenardite and sulfate reduction. Changes in the hydrochemical types of lakes lead to changes in the mineral composition of their bottom sediments. During low-water periods, autochthonous sedimentation prevails, and the portions of dolomite and clay minerals increase: in sulfate lakes, kaolinite and hydromica accumulate; in soda lakes, montmorillonite is additionally prominent. Concurrently, heavy oxygen isotope accumulates in carbonates. Further increase in water salinity is accompanied by the precipitation of gaylussite, trona, and anhydrite and by the ware transition from soda to sulfate types. The formation of thenardite changes the lake water from the sulfate to the chloride type. During the period of lake desalinization, allochthonous sedimentogenesis prevails, leading to the accumulation of clastic material in lacustrine sediments, primarily plagioclases and feldspars; in addition, carbonates with an isotopically lighter composition of oxygen accumulate.
V.A. Poturay1, V.N. Kompanichenko1, A.A. Redin2 1Institute for Complex Analysis of Regional Problems, Far Eastern Branch of the Russian Academy of Sciences, Birobidzhan, Russia 2Hydrogeological Survey of AO Kurort Belokurikha, Belokurikha, Russia
Keywords: Organic matter, thermal waters, genesis, bacterial activity, hydrocarbons
The present study is aimed at the determination of organic compounds in thermal waters of the Belokurikha deposit (Altai Territory), which is important both for balneology and for regional ecology. The TOC concentration ranges from 0.42 to 0.55 mg/L. Using capillary gas chromatography-mass spectrometry and solid phase extraction, 69 organic compounds were identified, which form 16 homologous series. Normal and isoalkanes (25%), carboxylic acids and their esters (24%), and aromatic hydrocarbons (14%) are predominant in the thermal waters. The molecular-weight distribution of normal hydrocarbons (the odd/even ratio is 1.3-1.5, ACL = 16.6-17.5) and the presence of characteristic compounds indicate that the organic matter in the studied waters is of autochthonous, predominantly bacterial origin. Some of the identified components suggest a low degree of technogenic pollution of the waters (phthalates and compounds containing a tert-butyl group and chlorine). Oxygen-bearing compounds might exert a therapeutic effect on the human body. Comparison of the studied thermal waters with Far Eastern hot springs showed both a great similarity in the distribution of organic compounds and a difference because of the contribution of plant detritus to the formation of the organic component of Far Eastern thermal waters.
E.I. Korytkin1,2, G.M. Mitrofanov1,3,4 1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia 2OOO SakhalinNIPI Nefti i Gaza, Yuzhno-Sakhalinsk, Russia 3Novosibirsk State University, Novosibirsk, Russia 4Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: 3D seismic exploration, classification, Bayesian classifier, prior probabilities, seismic facies extraction
The article considers the issues of determining the characteristics of target horizons using methods capable of learning on large volumes of heterogeneous data and high prediction accuracy. The methods are used to solve problems of seismic facies analysis at oil and gas fields, the main purpose of which is to reconstruct the sedimentatry rocks and predict lithofacies in the study area. The object of the study was one of the fields in the Volga-Ural region. An improved Bayesian classifier was used as a tool. It was used to determine promising distribution zones of the productive B2 formation reservoir of the Bobrikovian deposits of the Lower Carboniferous and to assess the hydrocarbon production potential. During the research, the effectiveness of the application of machine learning methods and the proposed improvements was analyzed.
I.P. Shcherbakov, A.E. Chmel
Ioffe Physics-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia
Keywords: Granite, combined load, dynamic fracturing, acoustic emission, trigger effect
Uniaxially compressed granite samples were subjected to pointed impact damage directed orthogonally to the compression. Generation of the impact-induced acoustic emission (AE) was recorded by a wide-band piezoelectric transducer made of high-sensitivity PZT ceramics. The AE time series were analyzed in the frequency ranges of 80-200 kHz (conventionally low-frequency range) and 300-500 kHz (high-frequency range). Energy distributions in AE time scans recorded in the lower frequency range follow the power law, which is characteristic of the cumulative process of microcrack formation, whereas distributions recorded in the high-frequency range are described by an exponential (Poisson-like) function characteristic of random, non-interacting AE-events. Concentration of microcracks in the low-frequency range was characterized by the Gutenberg-Richter b -value. At continuous impact energy, the b -value increased progressively with increasing uniaxial compression applied to the samples from zero to the highest subcritical value, which suggests lowered contribution of larger cracks. As the compression load approached (but without reaching) the ultimate strength, the impact-induced subthreshold macrofracture of the granite sample (trigger effect) occurred.
The paper describes the problem of distortion of stacking velocities estimated from CDP gathers caused by statics applied for compensation of the effect of near-surface (NSS) velocity anomalies. An analytical solution of the problem of stacking velocities correction for statics applied for NSS and deep velocity anomalies is presented. The results of numerical modeling demonstrate the high performance of the proposed solution. A comparative assessment of the accuracy of structural imaging with the proposed methodology and the option without velocity correction and other algorithms for solving the problem is provided.
Maxwell's equations and equations of two-velocity saturated porous
mediums hydrodynamics are combined under condition of absence of local
thermodynamic equilibrium. Equations describing relaxation of dielectric
polarization vector are inferred. The law of dielectric permittivity dispersion
in presence of two interacting relaxation processes is established.
Relationship between kinetic coefficients and complex dielectric permittivity
is shown, particularly relationship with hydrodynamic permeability of porous
medium. Method of determining hydrodynamic permeability of porous medium based
on its dielectric spectrum is established. Medium’s dielectric response to
external inductive effect is examined for boreholes in saturated porous media
The Angara-Kan block is an outcrop of the southwestern margin of the Siberian Craton, it is mostly composed of rocks of the Kan granulite complex and the Yenisey metavolcanic-metasedimentary complex. In this work we present the new data on composition, metamorphic condition and age of zircon and monazite of garnet-biotite schists of the Yenisey complex. Textural features, geochemical composition and wide range of zircon ages indicate formation of garnet-biotite schists during single-act metamorphism of terrigenous rocks. PT-conditions of metamorphism of garnet-biotite schists and garnet amphibolites are about P=7.2-8.2 kbar, T=700-730°C, they are similar to those of metavolanic rocks of the Yenisey complex. The age of metamorphic generation of zircons and monazites from garnet-biotite schists in the range of 720-730 million years correlates with the time of Neoproterozoic metamorphism of volcanic rocks of the Yenisei complex. The age spectra of Paleoproterozoic detrital zircons from garnet-biotite schists indicate two maxima: ca. 1.86 and ca. 1.78 Ga. The probable source of detrital zircons were granulites of the Kan complex, which underwent two stages of high-grade metamorphism at 1.89–1.85 and 1.8–1.77 Ga, respectively. The accumulation of terrigenous sediments was probably close in time to the formation of volcanics of the Yenisei complex at ⁓ 1.74 Ga. It is assumed that most sedimentary rocks of the Yenisei series were formed after the main orogenic events in the Angara-Kan block.
V.I. Malov1,2, V.D. Strakhovenko1,2, M.A. Gustaitis1,2, E.A. Ovdina1, G.I. Malov1 1V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk National Research State University, Novosibirsk,Russia
Keywords: Mercury; mercury flux; Hg; Altai; bottom sediments; lakes
This study presents the results of a comprehensive assessment of mercury content in bottom sediments of four high-altitude lakes on the Ukok Plateau (Altai, Russia): Zerlyukol-Nur, Krasnoye, Tyoply Klyuch, and Argamdzhi. The aim was to quantify mercury concentrations and evaluate its fluxes in sediments as indicators of global atmospheric pollution. Mercury levels range from 28 to 130 ng g⁻¹, with an average of 57.4 ± 21.4 ng g⁻¹, corresponding to background values for high-mountain lakes of the Northern Hemisphere. Elevated concentrations in the upper layers of three lakes reflect post-industrial contamination, whereas this trend is absent in Tyoply Klyuch, likely due to a thermal endogenous influence. Sedimentation rates of 0.18, 0.9 cm yr⁻¹ yield mercury fluxes of 3.9, 9.1 ng cm⁻² yr⁻¹, comparable to those reported for the southern Himalayas but lower than levels in industrially active regions. The findings indicate that the Ukok Plateau remains isolated from direct pollution sources and highlight its value as a background indicator area for evaluating transboundary mercury transport. This work fills a data gap on Hg distribution in remote high-mountain ecosystems and refines global mercury-cycling models.
The morphology, chemical composition, ore and placer mineral associations of gold placers of the Ursky ore cluster and the less studied Kasminsko-Chesnokovsky prospective area of northeastern Salair indicate numerous and diverse primary sources, and the presence of gold in intermediate collectors. The fineness of 970-1000‰ is mainly due to hypergene-transformed gold. Placers were formed mainly due to quartz, quartz-carbonate, quartz-(carbonate)-sulfide veins and stockworks of the gold stage of mineralization, including superimposed on barite-polymetallic, with fine and finely dispersed gold, mineralization of the Ursky ore cluster and on dikes of the main composition. One of the sources of gold is also metasomatites (carbonate-micaceous, quartzites, quartz-albite-epidote, with rutile), accompanying gold ore bodies, or not associated with them. Differences in the typomorphic properties of placer gold are due to different contributions of primary sources. In the placers of the upper part of the Ur River, the Zvonchikha River, this is probably predominantly gold mineralization superimposed on dikes of the main composition. The gold has a high fineness (>910‰), it contains copper impurity (up to 1-6 wt.%) and, in one case, inclusion of Pd telluride. Quartzites are also a possible source of Au (as at the Kopna deposit). In the lower part of the Ur river placer, the Au fineness and the amount of copper-bearing gold decrease, and the frequency of occurrence of gold with mercury impurity increases. Gold mineralization is probably superimposed on polymetallic or localized in the rocks of the pechorkinsky complex. Polymetallic gold-bearing mineralization is indicated by the presence of gold with a fineness below 820‰ (as at the Iyunsky deposit). The sources of gold in the placers of the Chesnokovka and Kurnichikha rivers, in addition to mineralization associated with basic dikes, are mineralization characterized by gold with a fineness of 820-910‰ (including very small and fine), usually containing mercury impurity. These may be quartz veins and metasomatites on terrigenous rocks of the Suenginsky formation, known in the area. Inclusions in gold of placers of the Kasminsko-Ursky ore district are represented by minerals of sulfide ores, metasomatites, weathering crusts. In the gold of the Kasminsko-Chesnokovsky area, in contrast to the gold of the Ursky ore cluster, no inclusions of copper minerals (chalcopyrite, bornite, covellite, tennantite), common in pyrite-polymetallic ores, were found. The typomorphic properties of gold of the Aprelsky deposit reflect the multiplicity of sources, among them there are quartz veins, metasomatites on rocks of the Pecherkinsky formation, possibly mineralization superimposed on polymetallic. The sources of gold of the Khristinovsky Yama placer are probably diverse and similar to those of the placers of the Ur and Zvonchikha rivers. The isoferroplatinum grain from the Khristinovsky Yama placer can be attributed to the vilyuisky type.
The article presents new data on the formation conditions of basalts and basaltic andesites of the Kharchinsky volcano (the Central Kamchatka Depression, CKD). It is shown that the liquidus association is represented by olivine (Fo91) and Cr-spinel, which crystallized in oxidized conditions NNO+0.4 – NNO+1.5 at temperatures of 1110 – 1210°C. Melt inclusion in olivine phenocrysts study gives opportunity to reconstruct the parental melts for basalts and basaltic andesites. These melts have Mg-high (Mg# ≈ 76), Al-low and Ca-low mafic compositions enriched in volatiles. Water content in melts could reach up to 5.5 wt.%. These melts have a peridotite source; also, pyroxenite component admixture could take place. Crystallization of melts could occur in several intermediate chambers (up to 1.5, at 5-7 and 11-13 kbar).
I. S. Gertsel1,2, A. A. Golyshev1,2 1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: VT6 alloy, boron carbide, Substrate preheating, microhardness, synchrotron radiation
The possibility of controlling the structural-phase composition of a VT6–
B4C titanium matrix composite during direct laser deposition was investigated. A
correlation was established between the laser processing parameters and the
resulting microstructure: changes in energy input led to changes in the
concentration of secondary phases (TiB, TiB2, TiC). Synchrotron radiation
diffraction was employed to obtain high-resolution diffraction patterns, which were
used to determine the qualitative phase composition of the fabricated titanium
matrix composites. It was demonstrated that using a high-energy set of processing
parameters results in a significant increase in microhardness, reaching up to 750
HV0.3.
Ch. A. Tsgoev1, D. I. Sakharov1, M. A. Bratenkov1, V. A. Travnikov1, A. V. Seredkin1,2, V. A. Kalinin1, D. V. Fomichev3,4,5, R. I. Mullyadzhanov1,2 1Novosibirsk National Research State University, Novosibirsk, Russia 2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia 3Novosibirsk National Research State University, Sirius Federal Territory, Krasnodar, Russia 4Sirius University, Moscow, Russia 5State Corporation Rosatom
Keywords: physics-informed neural networks, deep learning, Navier-Stokes equations
This paper presents several aspects of the application of physics-informed neural networks using the example of a two-dimensional steady-state problem of flow around an obstacle, modeled by the Navier-Stokes equations. The influence of the activation function, quantitative parameters of the training dataset, adaptive regularization, and adaptive meshing on the quality and accuracy of the solutions is investigated within a fixed neural network architecture. The interrelation between these factors and the modeling quality is analyzed to identify optimal conditions for improving the accuracy and stability of the solutions.
T. A. Ishmuratov1, A. Ya. Davletbaev1,2 1LLC "RN-BashNIPIneft", Ufa, Russia 2Ufa University of Science and Technology, Ufa, Russia
Keywords: sound velocity, annular space, bottomhole pressure, phase transitions, gas composition, oil and gas properties
A method is presented for estimating the average sound velocity in the annular space of a mechanized well, which is subsequently used to determine the gas-liquid interface (dynamic level). The proposed approach takes into account the distribution and variation of the gas composition, thermobaric conditions, and the presence of phase transitions. The key stage in solving the problem is determining the gas composition distribution from the wellhead to the gas-liquid interface. The approach is based on the laws of thermodynamics for equilibrium processes. The method has been tested on more than 100 wells across several oil fields in Western Siberia. The convergence of the analytical approach was verified by comparing its results with field experimental measurements of sound velocity obtained by echo sounding.
V. I. Borodulin, A. V. Ivanov, Yu. S. Kachanov, A. P. Roschektaev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: boundary layer of a swept wing, cylindrical turbulators, induced turbulence structure, jumps in integral parameters
The primary goal of this study is to investigate the mechanism of forced transition to turbulence in the laminar boundary layer of a swept wing, dominated by crossflow instability, using spanwise-periodic arrays of cylindrical turbulators. Measurements were carried out using hot-wire anemometry in a low-turbulence wind tunnel at ITAM SB RAS (Novosibirsk) at low subsonic freestream velocities on a model of a 25-degree swept wing. The Reynolds number based on cylinder height ranged from 565 to 3613. All major characteristics of the boundary layers were obtained, which are essential for constructing transfer functions for jumps in integral boundary layer parameters-important for numerical simulation of flows over swept wings with turbulators. The turbulence spectra were shown to be consistent with the Kolmogorov and Heisenberg laws. Empirical formulas by Falkner and Hama for the evolution of integral parameters in a three-dimensional boundary layer were verified and refined. This article represents Part 2 of the study.
I. K. Gimaltdinov, A. S. Rodionov, O. Yu. Valiakhmetova
Ufa State Petroleum Technological University, Ufa, Russia
Keywords: porous medium, bubbly liquid, waves, shock tube
The propagation of a wave with a step profile and a finite-duration impulse from a liquid into a porous medium saturated with either a bubbly or a “clean” liquid is studied. The effect of such waves on a solid wall with a saturated porous layer located in front of it is investigated. It is shown that the numerical results qualitatively agree well with known experimental data.
K. B. Sabitov, A. G. Khakimov
R. R. Mavlutov Institute of Mechanics, Ufa Federal Research Center, Russian Academy of Sciences, Ufa, Russia
Keywords: thin plate, liquid, gas, density, pressure, added mass, velocity potential, frequency spectrum, vibration mode shapes
The frequency spectrum and mode shapes of flexural vibrations of rectangular plates in contact with a liquid or gas are determined. An expression is derived for the distributed transverse load on a plate hinged along its contour. The plate surfaces are in contact with a medium characterized by varying density and pressure. The medium may be either compressible or incompressible. The effects of mean pressure, curvature of the mid-surface, and the added mass of the gaseous medium on the plate’s bending behavior are evaluated.
The deformation of an elastic body containing two thin anisotropic inclusions intersecting at a right angle is studied based on a mathematical model with unilateral boundary conditions. The inclusions intersect at an interior point of one of them, forming a T-shaped configuration within the elastic medium. One of the inclusions is debonded from the matrix, resulting in a crack. Boundary conditions on the crack surfaces are specified in the form of inequalities. To solve the problem numerically in the region with a cut, a domain decomposition method with the Uzawa algorithm is used. To determine the displacement functions of the semi-rigid inclusion, a method based on decomposing the space into a direct sum of subspaces is applied.
D. A. Pozharsky, E. D. Pozharskaya
Don State Technical University, Rostov-on-Don, Russia
Keywords: three-dimensional elastic wedge, periodic contact, integral equation, regularization
This paper investigates a three-dimensional normal contact problem involving an elastic wedge with one traction-free face and an infinite periodic straight-line system of rigid indenters arranged along the wedge edge (dihedral angle). The system of indenters induces infinite normal displacements on the wedge face (a special case being the half-space). To regularize the divergent kernel of the integral equation governing the contact pressures, an additional periodic system of normal forces is introduced outside the contact region. This system is aligned with the array of indenters and shares the same period. The forces in the regularizing array are equal in magnitude and directed opposite to those applied by the indenters. Two regularization cases are considered: one where the regularizing force chain is applied off the wedge edge (first case), and another where it acts directly on the edge (second case). To solve the regularized integral equation, the Galanov numerical method is employed, which simultaneously determines both the contact area and the contact pressure distribution.
A. L. Kazakov1,2, L. F. Spevak2 1Institute of System Dynamics and Control Theory, V. M. Matrosov Institute SB RAS, Irkutsk, Russia 2E. S. Gorkunov Institute of Machine Science, Ural Branch of RAS, Yekaterinburg, Russia
Keywords: nonlinear parabolic system, diffusion wave, existence theorem, exact solution, numerical method
Solutions of the diffusion wave type are constructed and analyzed for a system of two degenerate nonlinear parabolic equations. The problem of initiating a diffusion wave is considered for an arbitrary form of nonlinearity in the system and for arbitrary directions of motion of the zero fronts of the two target functions. A theorem is proved on the existence of four different analytical solutions depending on the propagation directions of the zero fronts. A new numerical method is proposed, which for the first time enables the solution of the problem for the case of oppositely directed motion of the two zero fronts. A new exact solution is explicitly constructed and used to verify the computational results. A numerical experiment is performed, demonstrating the convergence of the numerical method and its effectiveness across various problem parameters.
H. Hu1, C. Xiang1, Xi. Tian2, R. Piao1, S. Wang1 1College of Mechanical and Electrical Engineering, Anhui University of Science and Technology, Huainan, China 2School of Automotive Engineering, Anhui Vocational and Technical College, Hefei, China
Keywords: Mechanical Properties, Erosive wear performance, Blends, Epoxy resin, PAEK
In this paper, the modified polyaryletherketone (PAEK) was used as a toughening agent to prepare the PAEK/epoxy blends. Effect of PAEK on the erosive wear behaviors of blends was also investigated by the water jet technology. The surface morphologies of the wear scars were examined. With the increased of the PAEK content, the hardness and the impact toughness showed the phenomenon of first increased and then decreased. The erosive wear resistance of the epoxy resin blends was improved significantly, especially when PAEK content increases up to 35 phr. The erosion wear rate of the specimen shows 9.1% reduction than that of unmodified epoxy resin sample. The material removal occurred on the eroded surfaces of the epoxy blends due to the micro-ploughing, cracks, micro-cutting and plastic distortion. All these results suggested that the addition of PAEK could optimize the structural strength, indicating that the PAEK/epoxy blends are suitable for erosive environments.
A. Smahat1, A. Mankour1, E.H. Bensikaddour1, K. Bendine2 1Satellite development Center, Department of Mechanical research, Oran, Algeria 2Mechanics of Structures and Solids Laboratory, Sidi bel-Abbe`s, Algeria
Keywords: Functionally graded materials, Impact loading, Circular plates, deformation, low-velocity, thermal environment
This study delves into the impact of low-velocity loading and thermal effects on Functionally Graded Material (FGM) circular plates crucial in aeronautical and space engineering. Examining varied conditions, the focus lies on radial displacement and transverse deformations in hot, ambient, and cold environments. Notably, findings highlight an increased likelihood of damage in hotter scenarios, emphasizing the imperative need to design FGM plates with enhanced resistance against impact loads and thermal stresses in extreme conditions. These results bear crucial implications for aerospace applications, guiding the development of FGM plates that can effectively withstand challenges in diverse environments.
M.O.A. Ferreira1, Santos K.R. Dos1, R.V. Gelamo2, N.B. Leite2, C.A.R. Baptista3, H.C. Pinto1, J.A. Moreto1, T.J.P De Oliveira4 1Materials Engineering Department, São Carlos School of Engineering, University of São Paulo (USP), São Carlos, Brazil 2Federal University of Triângulo Mineiro (UFTM), Uberaba, Brazil 3Lorena School of Engineering, University of São Paulo (USP), Lorena, Brazil 4Federal University of Lavras, Department of Engineering, Lavras, Brazil
Keywords: Fatigue-corrosion synergy, Reactive sputtering technique, Aluminium alloy, Aircraft industry
This research investigates the influence of Nb2O5 coatings, produced by using reactive sputtering technique, on the surface of middle-tension specimens M(T), regarding fatigue crack growth curves (da/dN versus DK) under exposure to a 0.6 mol L-1 NaCl saline solution. Results demonstrated the corrosion process occurred in the vicinity of the crack tip, where stresses are elevated, and significant plastic deformation prevails, notably influenced by slip bands that induce micro-cracks, exposing fresh material layers to the corrosive surroundings. The Nb2O5 coatings enhanced the fatigue-corrosion resistance of the 2198-T851 aluminium alloy. This study marks an initial step towards more comprehensive investigations into the impact of Nb2O5 coating on improving the mechanical properties of the 2198-T851 aluminium alloy.
The experimental data on mass transfer during ethanol evaporation and combustion in the boundary layer on a horizontal surface are analyzed. The effects of a barrier (up to 15 mm high), external turbulence (up to 26%) and air velocity (up to 58 m/s), close to the flameout velocity in the boundary layer, are considered. The review is supplemented with experimental data for narrowing and expanding channels. The conclusion that the limits of mass transfer intensity during combustion are determined by the regularities for laminar and turbulent boundary layers on a smooth impermeable plate during evaporation without combustion is confirmed.
The paper considers spherical gas bubbles in liquid with radial oscillations induced by acoustic field. The account of development and application of the homobaric model is presented. Several publications on this topic have been discussed.
M.V. Kashkarova1, S.G. Skripkin1,2, M.A. Tsoi2, A.Yu. Kravtsova1,2 1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: high-speed imaging, CFD modeling, cavitation, periodic roughness, NACA 0012 hydrofoil, STAR CCM+
This work deals with the study of cavitation in a slit channel when flowing around NACA 0012 hydrofoils with smooth and periodic roughness on the surface. The research was aimed at the description of the dynamics of cavitation cavity development on smooth and rough hydrofoils and determination of differences between them. Computer modeling of cavitation flow in a slit channel formed behind an obstacle in the form of a wing was performed in the modern CFD package STAR CCM+. Visualization was obtained, computer modeling was carried out in a wide range of parameters, and a comparison with experimental data on the cavitating flow was made. The effect of periodic roughness on the features of occurrence and development of a cavitation cavity on the hydrofoil is described. The flow structure in roughness cells is shown. The obtained results can be used to control effectively the cavitation process in slit sections of various hydraulic engineering devices.
Results of numerical simulatgions of interaction of a supersonic boundary layer on a flat plate with an oblique shock wave generated by a thin wedge aligned at a right angle to the plate surface are reported. The problem is solved by means of combining a CFD code based on solving the Reynolds-averaged Navier-Stokes equations with the LOTRAN 3.0 software package based on the еN-method. Specific features of the flow structure with primary and secondary separation regions are identified. It is shown that the shock-induced pressure gradient leads to the develop-ment of Tollmien-Schlichting instability waves and crossflow instability.
V. M. Kulik
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: coating, compliance, steady state, transition period, viscoelastic properties
The paper describes the response of a viscoelastic layer glued onto a solid base to a non-stationary convective pressure wave. A complete equation of motion of coating material particles in the case of two-dimensional deformations is derived and it takes into account the viscosity of the medium. A system of equations for calculating the longitudinal and transverse dynamic compliance, determined by the ratio of the displacement components to the applied pressure, is obtained. The derived equations allow the description of not only stationary oscillations of the coating, but also the process of their stabilization. It is noted that, in addition to viscosity and Poisson ratio, stationary and dynamic compliances depend only on two parameters: the ratio of the disturbance wave velocity to the propagation velocity of shear oscillations in the coating and the ratio of the wavelength to the coating thickness. An example of calculating stationary compliance for a typical case of a silicone rubber coating is given. Attention is drawn to the need to take into account the transition period of the forced oscillation stabilization, since the coating cannot swing instantly due to inertia and viscosity. Known attempts to calculate this process have been analyzed.
N.P. Moshkin1, A.V. Fomina2, G.G. Chernykh3 1Lavrentév Institute of Hydrodynamics SB RAS, Novosibirsk, Russia 2Kemerovo State University Kuzbass Humanitarian Pedagogical Institute, Novokuznetsk, Russia 3Federal Research Center for Information and Computational Technologies, Novosibirsk, Russia
Keywords: turbulent mixing zone, turbulized homogeneous and stratified fluids, semi-empirical turbulence models, internal wave, numerical modeling
Using a numerical model that includes a system of averaged hydrodynamic equations in the Oberbeck-Boussinesq approximation, differential equations for the Reynolds stress transfer and dissipation rate, a numerical model of the evolution of a flat turbulent spot in a turbulent stratified medium (degenerate background turbulence) is constructed. The components of the mass flux vector and the variance of density fluctuations are found from algebraic presentations of the local equilibrium approximation. Numerical modeling of the evolution of the turbulent mixing zone and the internal waves generated by this zone in a turbulent linearly stratified medium is performed. The calculation results demonstrate a significant effect of background turbulence on the development of the turbulent spot and internal waves generated by the spot. A large-scale turbulent background leads to generation of internal waves of significantly lower amplitude.
O. Yu. Otmakhov, M. A. Pakhomov, N. P. Skibina, I. A. Chohar, V. I. Terekhov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: experiment, ejector, aerodynamics, Coanda effect, mixing chamber, distribution of static and dynamic pressures
The experimental results on the study of the flow structure and pressure distributions on the wall and along the axis of the Coanda ejector mixing chamber are presented. The experiments were carried out in the range of changes in the absolute value of the total pressure in the prechamber PK = 1.2 - 3.5 atm, which corresponded to both sub- and supercritical jet outflow regimes. The width of the annular gap through which the ejector flow was blown into the mixing chamber took the values h = 0.15, 0.25 and 0.5 mm. An increase in the vacuum on the wall in the initial part of the nozzle was observed with an increase in the total pressure. It was found that the static pressure distributions along the nozzle axis are characterized by the presence of a vacuum region almost along the entire length of the cylindrical channel. At subcritical jet outflows, recirculation zones can form in the vicinity of the channel axis near its inlet. A fundamentally different character of the velocity distribution and pulsation intensity in the cross-section of the mixing chamber is noted, depending on the outflow regimes.
M.A. Zasimova, N.G. Ivanov, V.V. Ris, E.D. Stepasheva
Peter the Great St. Petersburg Polytechnic University, St. Petersburg, Russia
Keywords: turbulent jet, rectangular cavity, self-oscillations, unsteady Reynolds-averaged Navier-Stokes equations
The paper presents the results of parametric numerical modeling of turbulent jet propagation from a slot into a confined space at a Reynolds number of 4×103. The data of 2D and 3D unsteady Reynolds-averaged Navier-Stokes calculations in the basic confined space configuration close to the experimental conditions of Mataoui et al. (2001) show that the Strouhal number values obtained in the 2D and 3D formulations differ approximately by 10%, but both results are within the uncertainty of the experimental data. The ranges of the open boundary area and the cavity height for which self-oscillation modes are realized are obtained. It is shown that self-oscillations disappear when the transverse size of the open end boundary becomes small and when the cavity height becomes close to its length.
Blocking of a subchannel is one possible scenario for accidents in an operating liquid metal fast breeding reactor. Herein, the understanding the flow behavior neat the locking sites is extremely important. This paper studies the effect of external impact from a sweeping jet on the flow structure in a slot channel behind the fluid lock. We demonstrated that the zone of influence of a sweeping jet on the flow pattern is limited. The spectral analysis method proved that the meandering frequency and frequency of vortex structures propagation in a slot channel corresponds to the Strouhal number equal 0.143. The research results in the case of zero external impact are in compliance with results from other authors.
A.G. Laptev1, A.A. Ahtmitshin2 1Kazan State Energy University, Kazan, Russia 2Engineering and Development Center Inzhehim, Kazan, Russia
Keywords: thermal effciency, mathematical model, experimental study, heat transfer enhancement, flow patterns
Experiments were conducted on lqiuid (water) heating by hot vapor in a plate heat exchanger. The coolant agent temperature and flow rates were meausred; the hat balance and heta tarnsfer equastions were applied for calculating the heat flux and heat tarnsferr coefficient asa function of heatwd water flow rate. The mathermatical models are developed for the heat number of tyrtansfer units and for liquid dispalcement in smooth channels. We developed a cellar model for coollant flow pattern while using the surface-type tarnsfer enhancers (wire inserts) and volumetric enhancers (chaotic packing). The calcuations and experimental data are in satisfactory agreement. Experimemntal and simulatiom methods demonstrated that the using of surafec-type enhancers in the problem of high-visocisty lqiuid heating (e.g., industoal oil) increaes the heat transfer coefficient by 2.75 - 6 times amnd the gain in thermal effiecny is about 2.4 - 3.2 times. The gains from using the volumetric-type enhancers are 15 - 20 times and 2 - 3 times, correspondingly, for heating with hot water. The dveloped mathematical model with accounting the flow patterns can be applied in designing or modernization of heat tarnsfer apparatuses in differnet industries.
A problem of controlled time-dependent reduction of wettability of rough metal surfaces obtained after laser ablation by means of periodic laser pulses is theoretically studied. The evolution of the contact angle of wetting of samples having a hierarchical surface structure after laser treatment is determined by their open-air storage, leading to spontaneous adsorption of an organic impurity. The theory of physical adsorption/desorption with a reversible quasi-chemical reaction in accordance with a linear mechanism supplemented with the Gibbs isotherm and the Young equation at the contact point of three phases is considered. The influence of the equilibrium constant and the fraction of the ad-sorbed impurity in ambient air on the rate of system transition to the equilibrium state is analyzed. The method used allows one to model the wettability transition mechanism and to calculate the time evolution of the contact angle of wetting in the case of adsorption of organic substances on the textured surface of the metal.
V.A. Babuk1, D.I. Kuklin1, S.Yu. Narizhny1, V.A. Sorokin2, L.S. Yanovkiy3 1Ustinov’s Baltic State Technical University VOENMEH, St-Petersburg, Russia 2Corporation “Machine Engineering Bureau “ISKRA”, Moscow, Russia 3Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry RAS
Keywords: agglomerate, condensed products, evolution, slag residues, validation
The simulation principles of slag formation process in the combustion chamber of power plants using high-energy materials such as solid and pasty propellants have been established. This process is determined by the processes of propellant burning, evolution of the multiphase flow inside a combustion chamber and the behavior of slag residues on structural elements. A sequence of using the characteristics of these processes to describe slag formation is shown. A new model for multiphase flow evolution is presented. This model is a key tool for describing the slag formation process. The features of this model are a detailed description of big-fraction solid particles transformation and considering the interaction of condensed and gaseous phases of the flow. The model is based on the combined Euler-Lagrange approach. To validate the model, an experimental study was conducted using a model engine based on aluminized paste propellant. The results of study bring a conclusion about the adequacy of simulation. The directions of further research are determined to solve the problem of simulation the processes under consideration of varying composition parameters and conditions within the combustion chamber.
V.E. Zhukov, N.N. Mezentseva
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: non-azeotropic mixture, alcohol-water mixture, internal intensifiers, heat transfer in the channel, pressure drop
It is known that passive heat transfer intensification in tubes is carried out by acting on the flow with inserted intensifiers or by changing the shape of the heat exchange surface. The presented work deals with the study of the in-tensification process using spherical turbulators located in a horizontal stainless steel channel. Experimental data were obtained on the heat transfer intensity and pressure drop during circulation of an alcohol-water mixture with a con-centration of 30% by weight at a pressure in the vessel of 0.03 - 0.04 MPa. The efficiency of spherical intensifiers and the pressure drop in the section with spherical intensifiers were compared with the efficiency of spiral intensifiers and the pressure drop in the section with spiral intensifiers at similar operating parameters. It was shown that the efficiency of spherical intensifiers is commensurate with the efficiency of spiral intensifiers at significantly lower pressure drops.
P.V. Zinin, P.A. Grishaev, K.M. Bulatov
Scientific-Technological Center of Unique Instrumentation of the Russian Academy of Sciences, Moscow,Russia
Keywords: remote temperature measuring, remote emissivity measuring, least squares method, polynomial model for emissivity, temperature measurement error, emissivity measurement error
The paper is devoted to non-contact measurements for temperature and emissivity. There are many parameters controlling emissivity: temperature, wavelength, surface condition, etc. There are cases for insufficiently detailed approximation for a body with emissivity depends on the wavelength as an issue of processing the remote measurements of emissivity. A hybrid method aimed to reducing thee multidimensional minimization to one-dimensional case for calculating the emissivity decomposition coefficients is presented. The grey body, linear and quadratic emissivity models are considered. An increasing number of solutions with increasing number coefficients of polynomial decomposition for emissivity is observed. The approach of choosing a proper solution is developed. The limitations on the model parameters numbers are presented: this is related to a growth of relative uncertainties in each parameter and with using the Akaike criterion.
S.V. Stankus, R.A. Khairulin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: intermetallics of lanthanides, density, thermal expansion, solid and liquid states, gamma method, prediction of properties
The density of CeAl2 and NdAl2 intermetallic compounds in the temperature range of 1550 - 1930 K in the so-lid and liquid states was measured using the method of transmitting samples with a narrow gamma-ray beam with an error of 0.5 - 0.8 %. Approximation dependences for the density of melts of the studied alloys were obtained, and changes in the density during melting and crystallization were determined. The density of melts of a number of other LnAl2 intermetallics of cerium subgroup of lanthanides was empirically estimated.
