bluuebunny/crossref_metadata_2025 huggingface dataset:
ASI Space Science Data Center participation to high-school outreach program
Authors: Zinzi Angelo , Pittori Carlotta , Tagliamonte Rosa , Nichelli Elisa
Published: December 2020

Since 2017 the Italian Space Agency (ASI) participates to so-called ‘Alternanza Scuola-Lavoro’ (i.e. ‘school-work synergy’) outreach projects promoted by the Italian government, and the ASI Space Science Data Center (SSDC) actively contributes to them, with the primary aim of bringing students closer to space-related activities before choosing their university studies.

The SSDC outreach programme is split into two parts: one theoretical, in which relevant topic are presented and explained, and one practical, consisting of hands-on activities aimed to replicate scientific analysis of real space data. The impact of the programme on students’ attitude is then evaluated by means of questionnaires specifically designed to gather information on the students’ educational background, the level of engagement triggered by the proposed activities, their relevance to school-based activities, and the perceived ease of understanding of the covered topics.

As reported in this paper, the analysis of the answers clearly shows that students greatly appreciated this outreach project, supporting its possible expansion and development, even articulated in a more complex pedagogical plan, as already done for one school in a pilot case. Therefore, we plan to expand these activities in the next future both by including new topics (e.g. cosmology, stellar physics), and by proposing new more articulated teaching pathways inclusive of on-site activities in the classroom.
Studies on the near-surface trapping of deuterium in implantation experiments
Authors: Maya P.N. , Mukherjee S. , Sharma P. , Karki V. , Singh M. , Satyaprasad A. , Kumar R. , Vala S. , Abhangi M. , Kannan S. , Pujari P.K. , Raole P.M. , Deshpande S.P.
Published: December 2020

Surface-shifted deuterium profiles are re-examined in deuterium-ion irradiation experiments by using a combined experimental and modelling approach. Recrystallized tungsten foil samples were irradiated with energetic deuterium ions and the defect and deuterium depth profiles were studied using positron annihilation spectroscopy and secondary ion mass spectroscopy. We report direct experimental evidence of trapping of deuterium at the vacancies created by the deuterium ions themselves during the implantation by using positron annihilation studies. The deuterium profile is simulated using a Monte-Carlo diffusion model by taking into account the defect-aided diffusion of deuterium due to the local strain field created by the vacancies. The simulations also elucidate the role of the anisotropy in the diffusion and trapping of deuterium in ion-implantation experiments in metals.
Effect of the channel divergence ratio on heat transfer in a turbulent flow around the rib-step system
Authors: Barsukov A V , Terekhov V V , Terekhov V I
Published: December 2020

The article presents the result of the numerical simulation of the turbulent flow for a rib-step system by the RANS method at the Reynolds number, calculated by the step height and average flow rate velocity, Re = 5000. The data obtained in these studies showed the influence of divergence ratio on heat transfer in a flat channel with a transverse rib acting as a vortex generator. It is shown that with an increase in the divergence ratio, the length of the recirculation zone increases, while the position of the heat transfer maximum varies slightly.
Thermal imaging of laminar-turbulent transition on experimental model of swept wing. Creating database of experimental data
Authors: Borodulin V I , Ivanov A V , Mischenko D A
Published: December 2020

The paper is devoted to the problem of creation of experimental database obtained due to systematic extended series of experiments aimed at registering the laminar-turbulent transition in boundary layers on a swept wing model. The experiments were carried out in a low-turbulence wind tunnel in boundary layers developed on ‘suction’ and ‘pressure’ sides of experimental model of an airfoil in a broad range of problem parameters (angle of attack, free-stream velocity, free-stream turbulence etc.). The main feature of performed experiments is using of a new panoramic experimental technique based on application of sensitive infrared camera. Digital postprocessing of obtained thermograms that gave a possibility to detect the position of transition occurred due to amplification of cross-flow instability modes, TS-waves or both of them. The article includes description of the approaches used and the first preliminary results.
Large-eddy simulation of a swirling flow in a model combustion chamber
Authors: Hrebtov M Yu , Palkin E V , Mullyadzhanov R I
Published: December 2020

Large-eddy simulations of the swirling annular jet flow are performed in a model of a combustion chamber at two different flow regimes with and without the central jet at Re = 5000. The mesh convergence study provides well-described time-averaged statistics even for a coarse mesh, while small-scale features are only resolved after a proper refinement. The central jet is shown to significantly modify the recirculation bubble and partially suppress the precessing vortex core.
Numerical investigation of the effect of coherent structures on adiabatic film cooling effectiveness of a flat plate
Authors: Kozyulin N N , Hrebtov M Yu
Published: December 2020

We present a numerical simulation of the flat plate film cooling setup with an elliptical nozzle with a 35° inclination angle. The baseline simulation mimics an experimental setup from [1]. We introduce a modification to the nozzle channel shape by including a backward step with a fixed width, while keeping the nozzle outlet shape fixed. The modification leads to an appearance of a recirculation zone inside the nozzle, which eventually becomes unstable developing a periodic vortex street formation. This change in the flow behaviour improves overall effectiveness of the film cooling by reducing the vertical component and promoting the lateral component of the turbulent diffusion.
Investigation of the influence of the surface material of a streamlined round cylinder on the parameters of the near wake using PIV and POD methods
Authors: Lebedev A S , Dobroselsky K G , Lobasov A S
Published: December 2020

In this paper, the influence of the surface material of a streamlined cylinder on the characteristics of large-scale velocity pulsations is experimentally investigated using the methods of studying the flow structure, namely PIV (Particle Image Velocimetry) and POD (Proper Orthogonal Decomposition). A comparison of the parameters of the near wake in the range of Reynolds numbers of 70 000 – 180 000 is presented for cylinders made of vacuum rubber (hydrophilic material) and fluoroplast (hydrophobic material) of the same diameter. Using the PIV method, instantaneous and averaged velocity fields are obtained. The size of the separation zone is determined based on the average velocity fields. The spatial shape and kinetic energy of the observed large-scale ripples in the wake region are analyzed using the POD statistical method. In the studied range, the transition to the critical flow mode for the fluoroplast cylinder is recorded. For the case of flow around a rubber cylinder, the character of pulsations in the wake zone remains unchanged throughout the studied range.
Numerical and Physical Simulation of Heat Transfer Enhancement Using Vortex Generators
Authors: Mironov A A , Isaev S A , Popov I A , Skrypnik A N , Dushin N S , Mikheev N I
Published: December 2020

Vortex generation and flow disruption in fluid ducts by means of surface modification is a widely used passive heat transfer augmentation technique. The present paper contains the results of numerical and experimental studies of the flow fields and heat transfer enhancement in the ducts with oval-trench and oval-arc shaped dimples applied to the heat transfer surface. The results of the numerical study of the flow over the dimpled surface with periodic boundaries are verified by experimental visualization of the flow and temperature fields. The influence of characteristic geometrical parameters of the dimples on the heat transfer, friction factor, and flow structure in heat-exchange ducts has been obtained. Preliminary results on the artificial neural networks application on heat transfer and friction factor assessment for the flow over dimpled surfaces are presented.
Investigation of the influence of the three-dimensional roughness element on the flow over trapezoidal flying wing
Authors: Pavlenko A M , Kaprilevskaya V S , Kozlov V V
Published: December 2020

The paper is devoted to the investigation of the flow and effects taken place when three-dimensional roughness element is placed on the leading edge of the trapezoidal flying wing. The experimental study was carried out in the working park of the subsonic wind tunnel. Low Reynolds numbers allowed running experiments at in-flight-like conditions. Pictures of the flow structure were obtained by liquid crystal thermography. It was found that longitudinal disturbances on the leading edge and behind three-dimensional roughness element form differently. Inner configuration of the longitudinal structure was shown by hot-wire measurements.
Symmetry breaking in annular jets with different blockage ratio
Authors: Ryzhenkov V O , Mullyadzhanov R I
Published: December 2020

We perform direct numerical simulations of the annular laminar jet flows for two inner-to-outer diameter (blockage) ratios br = d / D = 0.5, 0.9 in the range of the Reynolds number based on the bulk velocity inside the nozzle and its outer diameter Re = 200 – 400. In spite of the axisymmetric formulation, asymmetric states are observed for moderate and high Re. A gradual increase of the Reynolds number allow building a regime map. The symmetry-asymmetry transition Reynolds number decreases with the increase of br, while the steady-unsteady transition Reynolds numbers are close for both br. The degree of asymmetry increases with the increase of Re, leading to a shift of the global stagnation point from the axis of symmetry.
Experimental study of a turbulent structure in coplanar channels
Authors: Terekhov V I , Zolotukhin A V , Chohar I A
Published: December 2020

The experimental results of a three-dimensional turbulent flow structure inside the cells of flat coplanar channels with mutually intersecting edges on opposite walls are presented. In the experiments, a two-component laser Doppler speed meter is used, which allows measuring the averaged and pulsating velocity components. It is shown that a flow structure varies depending on a place of measurements inside a coplanar channels cell.
Evolution of mass flow and total temperature pulsations in flat-plate and swept-wing boundary layers at Mach 2 and 2.5
Authors: Yatskikh A A , Kosinov A D , Semionov N V , Ermolaev Y G , Panina A V , Kocharin V L , Afanasev L V
Published: December 2020

The experimental data on the development of natural disturbances during the laminar-turbulent transition in the boundary layers of a flat plate and a swept wing with a supersonic leading edge at Mach 2 and 2.5 are analyzed. Data are obtained using a hot-wire anemometer in the automatic scanning mode for overheating of the probe. The levels of pulsations of mass flow and disturbances of total temperature are determined using the modified diagrammatic method of Kovasznay taking into account the coefficient of correlation. It was found that at all stages of the laminar-turbulent transition of the flow in the boundary layer, the ratio of the levels of pulsations of the total temperature and pulsations of the mass flow and the correlation coefficient remain almost constant.
IR diagnostics of a flame of a new burner when burning liquid hydrocarbons in a steam jet
Authors: Anufriev I S , Kopyev E. P. , Loboda E. L. , Agafontsev M. V. , Mukhina M. A. , Sadkin I. S.
Published: December 2020

In the present work, we performed IR diagnostics in the external flame of a new burner using the example of waste engine oil being sprayed by a high-speed jet of superheated steam. The experiments were carried out in a wide range of operating parameters (steam flow rate and temperature and fuel flow rate). In measurements, we used a FLIR thermal imaging camera of the special JADE J530SB series and platinum-rhodium-platinum-rhodium thermocouple of type B. Instantaneous and average temperature fields are obtained. The influence of device operation parameters on the temperature in the external flame of the burner is established. The maximum temperature reaches 1240°C. With increasing mass concentration of steam, a decrease in temperature is observed. This is due to dilution of a combustible mixture and a decrease in its heat capacity. A decrease in the flame temperature in the presence of steam may indicate a decrease in formation of thermal nitrogen oxides.
Thermal decomposition of polyethylene agglomerates in a porous medium
Authors: Donskoy I G , Svishchev D A , Kozlov A N , Penzik M V
Published: December 2020

Fixed-bed combustion of compositions with polymeric materials (for example, municipal solid waste) is often difficult due to the agglomeration phenomenon: when heated, the waste particles swell and emit a significant amount of viscous products, resulting in formation of clumps of particles that have low air permeability. Using experimental and theoretical models, some features of the formation and decomposition of agglomerates are investigated. Samples of the agglomerates were prepared in a laboratory batch unit by heating a mixture of polyethylene granules and clay particles. Using a mathematical model, numerical calculations of the heating regimes were performed under the conditions of an experimental unit. A change in the shape of the agglomerate at different points in time is considered.
Changes in thermal conductivity of wood during its thermochemical conversion
Authors: Donskoy I G , Svishchev D A , Shamanskiy V A
Published: December 2020

Plant biomass is a fuel with better environmental characteristics than fossil fuels. The paper considers the effect of wood fuel conversion on its thermophysical properties. The measurements made allow us to establish a relationship between the degree of conversion and the coefficient of thermal conductivity. Thermal conductivity increases linearly with increasing density of samples and decreases as the pyrolysis proceeds, which is associated with a change in the porous structure and chemical composition of the material. The data obtained are used in a mathematical model of the pyrolysis of a wood particle. The influence of the anisotropy of the thermal conductivity coefficient on the characteristic drying and pyrolysis times is estimated.
Influence of the relative momentum flux ratio on the mixing of hydrogen jets in an M=4 crossflow
Authors: Fedorova N N , Goldfeld M A , Valger S A
Published: December 2020

The paper presents the results of numerical simulation of the 3D flows in a plane channel with the abrupt expansion. Sonic hydrogen jets are supplied from two circle orifices located opposite each other on the channel walls before the backward-facing step. The numerical simulations are carried out under the conditions of experiments performed at the hot-shot wind tunnel IT-302M ITAM SB RAS for the following flow parameters: Mach number at the entrance of the channel M = 3.84, the total temperature T0 = 1715 K, and the total pressure P0 = 6.5 MPa. Calculations were performed with a change in the jet supply pressure from 0.4 to 3.6 MPa, which ensures the variation in the jet-to-crossflow momentum flux ratio in the range of J = 0.7 ÷ 6. Mathematical modeling was performed in ANSYS Fluent based on the Reynolds-Averaged Navier-Stokes equations supplemented by the k-ω SST turbulence model. A comparison of the calculated and experimental data on the flow structure, as well as the static pressure distributions on the walls, indicates a satisfactory agreement. The calculated results made it possible to obtain a clearer understanding of the 3D flow structure in the channel and reveal the influence of the injection pressure on the level of mixing.
Heterogeneous and platinum-initiated homogeneous combustion of nitrogen-containing heterocyclic compounds in the argon and water vapor media at elevated pressure
Authors: Fedyaeva O N , Artamonov D O , Vostrikov A A
Published: December 2020

The paper presents the results on the oxidation of pyrrole and pyridine in the argon and water vapor media at high pressure and uniform heating of the tubular stainless steel reactor to 823 K. Experiments were carried out with lean and stoichiometric mixtures (fuel equivalence ratio φ = 0.78–1.01) at their dilution level x
D = 36–65% mol. Based on the time dependences of the reaction mixture temperature, it is revealed that oxidation proceeds via the mechanisms of homogeneous and heterogeneous reactions. It was found that the oxidation rate of pyrrole depends on the amount of corrosion products accumulated on the reactor wall. It is shown that a Pt-Rh/Pt thermocouple inserted into the center of the reaction volume intensifies pyridine oxidation in the near-surface region. The difference in the oxidation mechanisms of pyrrole and pyridine is explained by the structure of their molecules.
Superstructures in a diffusion torch
Authors: Lemanov V V , Lukashov V V , Sharov K A
Published: December 2020

The paper presents the experimental results for isothermal flows (CO2, propane) and diffusion flames (C3H8 or H2 mixed with CO2). Optical method of PIV (Particle Image Velocimetry) and flow visualization are used. The paper considers the features of the effect of vortex superstructures on an attached diffusion plume. When superstructures interact with the flame front, the question of choosing the determining scales becomes ambiguous. Apparently, the features of the perturbation interaction can depend on the acoustic characteristics of the flows and, accordingly, on the nature of the density distribution in the plume.
Three-dimensional modeling of gas injection into a closed liquid-filled tube region
Authors: Alekseev M V , Vozhakov V S , Lezhnin S I , Pribaturin N A
Published: December 2020

Three-dimensional modeling of air injection into a closed pipe region filled with liquid (water, liquid lead) is carried out at high pressure drops. It is shown that in the three-dimensional calculation, the instability of the interphase surface in the form of ring waves of deformation on the upper surface of the projectile is significantly manifested. When air is injected into water, the difference in the configuration of the interphase surface obtained in axisymmetric (two-dimensional) and three-dimensional calculations is insignificant. When injected into a liquid with a substantially higher density (liquid lead), this difference is especially pronounced in the compression phase of the gas projectile.
Reflection of a shock wave from a finely dispersed medium of low concentrations
Authors: Bashirova K I , Mikhaylenko C I
Published: December 2020

A model of a shock tube is prepared to study the behaviour of a shock wave in a layer of light elastic granular particles. Computational experiments are made using the OpenFOAM package. The prepared model allows carrying out simulations for pressure between 105 and 104 Pa and concentration of particles of 20%. Results are obtained on pressures in different time moments, depending on different densities of granular particles. An increase of the density of the granular particles is shown to decrease the blurring of the boundary between the media. It is also noted that a decrease in the density leads to double pressure peaks.
Modeling bubble distribution and heat transfer in polydispersed gas-liquid flow in a backward-facing step
Authors: Bogatko T V , Pakhomov M A
Published: December 2020

The numerical results on the flow, bubble distributions and heat transfer in a bubbly polydispersed flow in a horizontal duct with a backward-facing step are presented. The numerical model uses the Eulerian approach taking into account the back effects of bubbles on the mean and turbulent characteristics of the carrier fluid phase. The model takes into account the interphase momentum transfer, bubble break-up and coalescence processes. The set of 2D RANS equations is used for modeling two-phase bubbly flows. Turbulence of the carrier fluid phase is predicted using the second moment closure. The method of δ-function approximation is employed for simulation of gas bubble break-up and coalescence. The effect of the gas volumetric flow rate ratios on the flow structure and heat transfer in the two-phase flow is numerically studied. An increase in the gas volumetric flow rate ratios leads to a significant increase in the wall friction coefficient (almost 1.5 times in comparison with the single-phase flow regime). The addition of air bubbles results in a significant increase in the heat transfer rate (up to 50%).
Research of heat and mass transfer parameters at drying poly (ethylene terephthalate) granules
Authors: Geller Yu A , Antanenkova I S , Shatskikh Yu V
Published: December 2020

In this article, drying characteristics were studied for polyethylene terephthalate (PET) granules. For data analysis, a modified quasistationary method was used. The values of the reduced time and the hydrodynamic intensity index were obtained for the generalized drying curve of the entire drying process in the temperature range from 120 to 185°C. The duration of the first drying period of PET granules was determined for all experiments.
Application of the PTV with the use of a light-field camera to study three-dimensional wave regimes of liquid film flow
Authors: Kvon A Z , Bobylev A V , Guzanov V V , Kharlamov S M
Published: December 2020

We present the results of studying the influence of surfactants on three-dimensional waves, in particular, on the flow structures in the wave. Volumetric fluid velocity measurements in waves, as well as the determination of their shape, were carried out using a light field camera. An aqueous solution of the nonionic surfactant Triton-X was used as a working fluid. The presence of surfactant leads to a significant change in the structure of the transverse flow regions under the main hump of the wave. Besides, capillary precursor and backflow in it are suppressed.
Reflection of sound pulses from the boundary of the bubble medium
Authors: Ogorodnikov I A
Published: December 2020

The reflection of sound and radiation of a bubble medium under excitation by a short sound wave are studied for different values of the volume concentration of bubbles. It is shown that at the beginning of the interaction of the wave with the medium, reflection occurs as from a structureless soft boundary, which at the end of the interaction is replaced by radiation from an excited medium. The dependences of the reflection coefficient are obtained and the spectral characteristics of the radiation of the bubble medium are determined at the initial stage of the process and at large times when the radiation is steady-state. It is shown that the emission spectrum of the layer is continuous with a maximum in the frequency range of volume pulsations of free bubbles.
Jump of azimuthal velocity in a creeping two-fluid swirling flow
Authors: Sharifullin B R , Naumov I V , Kravtsova A Yu , Shtern V N
Published: December 2020

This work reveals a jump of azimuthal velocity at the interface that can be important for vortex bioreactors. The rotating lid controls the flow of two fluids in a vertical cylindrical container, the other walls of which are stationary. Near the lid, a centrifugal force pushes the upper fluid toward the sidewall, thereby developing its centrifugal meridional circulation. This motion drives the bulk counter-circulation in the lower fluid at a slow rotation. The use of sunflower oil for the upper fluid, alcohol-glycerine solutions for the lower fluid and the assembly of averaged PIV images allow measuring velocity and visualizing pattern even in a creeping motion. This advanced experimental method helps to detect velocity jumps occurring at the interface.
Computational study of cutting transport by drilling fluids in directional wells
Authors: Zhigarev V A , Pryazhnikov M I , Matveev A V , Mikhienkova E I , Guzei D V
Published: December 2020

The paper presents the computation results of the cutting transport in directional wells. Two samples of oil-based muds were prepared. The rheological parameters, incorporated in the computation model, were measured. The geometry of the real well was used for the computation. Three well slopes equal to 15, 45, 75 degrees were studied. The sludge velocity profiles in the annular channels were obtained. The average volumetric value of the particle slip velocity was obtained (the difference between the drilling fluid velocity and the sludge velocity).
Shape control of the crystal-melt interface in the Bridgman method
Authors: Kislitsyn S A , Berdnikov V S , Mitin K A
Published: December 2020

The processes of silicon crystallization in flat-bottomed cylindrical graphite crucibles in the modes of conjugate convective heat transfer with allowance for latent heat are numerically investigated. The influence of hydrodynamics and heat transfer on the local shape of the crystal-melt interface has been studied. The hydrodynamics of a silicon melt is investigated in the modes of thermogravitational and thermal gravitational-centrifugal convection. First, the effect of the velocity of lowering the crucible into the cold zone was studied. Then, at the set crucible lowering velocity, the influence of the crucible angular velocity was studied. The problems were solved in a nonstationary formulation by the finite element method.
Study of the effect of three-dimensional capillary-porous coatings with various microstructural parameters on heat transfer and critical heat flux at pool boiling of nitrogen
Authors: Kuznetsov D V , Pavlenko A N , Chernyavskiy A N , Radyuk A A
Published: December 2020

An experimental study of the effect of capillary-porous coatings obtained by directional plasma spraying on heat transfer and critical heat fluxes during pool boiling of nitrogen under conditions of stationary heat release on copper tubular heaters with a diameter of 16 mm was carried out. It is shown that for the coating with the highest porosity, the maximum increase in the critical heat flux is 1.8 times higher than that for a smooth heater. The maximum heat transfer coefficients were observed on TCP coatings in the region of low heat fluxes, which were up to 3.5 times higher than the heat transfer coefficients on a smooth heater. The effect of the thickness of the residual layer of microstructured capillary-porous coatings on heat transfer during nucleate boiling is shown. Based on the data of high-speed video recording, it was shown that the intensification of heat transfer during boiling on structured capillary-porous surfaces is not associated with an increase in the nucleation site density. Revealed pulsating nature of boiling in the region of high heat fluxes is characterized by the periodic formation and departure of vapor conglomerates along the surface of the heater.
Condensation growth of microdroplets levitating over a heated liquid film
Authors: Shatekova A I
Published: December 2020

This work is devoted to the study of such an interesting phenomenon as levitation of liquid microdroplets above the surface of a heated film. Levitating microdroplets of liquid are formed due to condensation of the upward flow of steam. The height of the drop levitation is comparable to their size. This paper presents new experimental data on the dependence of the droplet diameter on time. Microdroplets of liquid being in a two-dimensional array of microdroplets and levitating above the heated liquid film constantly grow due to condensation. The diameter of the droplets practically linearly increases with time. The obtained non-trivial results require further careful research.
Intensification of heat transfer in falling films on a bundle of horizontal tubes with microstructured surface
Authors: Volodin O A , Pecherkin N I , Pavlenko A N , Zubkov N N , Kataev A I , Mironova I B , Das M K
Published: December 2020

Experimental results on measuring heat transfer in falling films of R21 refrigerant on a bundle of horizontal tubes with structured surfaces are presented. The experiments were carried out in the range of Reynolds number of the saturated liquid film from 500 to 1500 at a pressure of 3 bar in the evaporator. To intensify heat transfer, copper tubes with an external surface treated by the method of deformational cutting (MDC) were used. Three types of structures were used: structure No. 1 with half-closed microcavities, structure No. 2 with a rhomboid shape, and structure No. 3 created on the basis of structure No. 2 with additional transverse ribbing. It was shown that the studied types of structures can significantly increase the heat transfer coefficient as compared to a smooth surface. The structure with half-closed microcavities was the most effective for heat transfer enhancement.
Mathematical model for predicting the formation of ferrous deposits during coal combustion
Authors: Chernetskiy M. Yu. , Butakov E. B.
Published: December 2020

For the first time, on the basis of a combined model of the principal component method and neural network modeling method, a unified method for evaluating coals for the formation of strong ferrous deposits is proposed, taking into account the ash composition, combustion conditions and the degree of grinding. The results of predicting the propensity to form ferrous deposits of Rfe have shown acceptable accuracy of determination. Expanding the experimental database on different types of coals will improve the accuracy of modeling and the widespread use of this technique in the energy sector.
Laboratory setup for microwave drying of brown moisture carbon
Authors: Karelin V A , Salomatov Vl V
Published: December 2020

A setup has been created to study the drying of wet coals by microwave radiation with a frequency of 2.45 GHz. Time dependences of humidity and surface temperature of brown coal samples from the Talovskoye deposit in Siberia are measured at an absorbed energy density of about 30 W g−1. The analysis of the data obtained is carried out and the mechanisms of possible processes that explain the observed patterns are considered.
Experimental study of heat transfer processes during the operation of WWER steam generator in emergency mode on a single-tube model
Authors: Shlepkin A S , Morozov A V , Sakhipgareev A R
Published: December 2020

The paper presents the results of experimental research of the heat transfer processes during the operation of a WWER steam generator in emergency condensation mode. The experiments are carried out at a research facility with a test section in the form of a single-tube model of a steam generator. The geometric characteristics of the tube and the main research parameters, such as temperature and pressure, are similar to the real steam generator. Several stages of research are planned: with pure water steam, with a fixed concentration of boiling boric acid and with a variable concentration of acid in the solution. The results of the first series of experiments performed on pure water steam are presented. As a result of research, the heat flux density is determined, and the values of the heat transfer coefficient during steam condensation in a single horizontal tube are calculated.
Equation of state of hard-sphere fluid in nanoporous media
Authors: Andryushchenko V A , Boyko E V
Published: December 2020

The present work is devoted to the study of fluid equations of state in nanoporous media. The modelling is carried out in the framework of the molecular dynamics method using the potential of hard spheres. The dependences of the compressibility factor on packing fraction are studied for various characteristic pore sizes, porosities, and types of grains packing of a porous medium. It is shown that for all cases considered, deviations of the obtained equations of state from the Carnahan-Starling equation of state are insignificant. These deviations may be due to the presence of restricted zones in a porous medium inaccessible to fluid molecules that is also discussed in the work.
Mechanism of formation of intermetallic coatings by the Cold Spray Technology
Authors: Kiselev S P , Kiselev V P , Maximovsky E A , Vidyuk T A , Ukhina A V , Shikalov V S
Published: December 2020

In the present paper, results of a study of a TinAlm intermetallic coating obtained on the surface of titanium (Ti) by the method of Cold Gas Spraying (CGS) and heating to a temperature above the melting point of aluminum (Al) are reported. It is shown that the structure of the resultant coating depends on the heating temperature. At temperature T = 930K the coating consists of a TiAl3 intermetallic layer. At temperature T = 1270K a layered coating is formed. In this coating, a TiAl3 intermetallic layer, adjacent to the Ti surface, is followed by a second intermetallic layer consisting of Ti3Al and Ti2Al sublayers. The microhardness of the Ti3Al/Ti2Al double-layer coating proves to be three times higher than that of Ti. A qualitative explanation to the mechanism of formation of the layered coating is proposed.
Experimental study of the thermocapillary rupture dynamics of water and ethanol layers
Authors: Kochkin D Y , Zaitsev D V , Mungalov A S , Kabov O A
Published: December 2020

Rupture dynamics of thin (500 μm) horizontal liquid films of water and ethanol was experimentally investigated during non-uniform heating from the side of smooth substrate. On the same substrate under similar heating conditions, the propagation rate of a dry spot in a horizontal water film was found to be several orders of magnitude higher than the rate of propagation of a dry spot in an ethanol layer.
Determining thickness and optical properties of a-SiOx thin films by PUMA and envelope method
Authors: Merkulova I E
Published: December 2020

The gas-jet electron beam plasma chemical vapor deposition method was used for silicon suboxide (a-SiOx) thin films synthesis. According to the EDS data, stoichiometric coefficient of the films varied from 0.5 to 1.63 with changes in the flow rate of 5%SiH4+95%Ar gas mixture (R) from 89 to 18 sccm. Spectral transmittance, containing interference maxima and minima, was obtained in the range from 300 to 1000 nm. The refractive index and the thickness of a-SiOx thin films obtained from transmission spectra by the envelope method and PUMA were in good agreement with each other. The refractive index of the thin films at 650 nm increased from 1.6 to 3.1 and the film thickness changed from 500 to 1200 nm with an increase of R. The thickness values discrepancy for sample synthesized with R=18 sccm may be explained as the difficulty of using PUMA for systems with close refractive index of the film and the substrate.
Experimental study of oil displacement from a porous medium using nanosuspension
Authors: Minakov A V , Zhigarev V A , Pryazhnikov M I , Guzei D V
Published: December 2020

The paper presents the results of an experimental study of oil displacement by distilled water and an aqueous suspension of aluminum oxide nanoparticles. The correlation of extracted oil volume on the flow rate of the displacing fluid is obtained, and the pressure drop during the pumping of the displacing fluid through the rock sample is measured. It has been revealed that the suspension of nanoparticles can significantly improve the extraction of oil from sandstone.
Gas-discharge plasma diagnostics by a continuous spectrum of optical radiation
Authors: Pinaev V A , Isupov M V
Published: December 2020

In the present work, plasma diagnostics method based on the measurement and theoretical analysis of continuous emission spectrum of a gas discharge was discussed. Using the method, electron temperatures of a DC glow discharge and ferromagnetic enhanced inductive discharge were determined for inert gases in the gas pressure range of 20–200 Pa. Experimental results were compared with the results of numerical calculations for the ferromagnetic enhanced inductive discharge and DC glow discharge. A satisfactory agreement between the optically measured and numerically calculated values of electron temperature was shown.
Experimental study of heat transfer in two-phase flow regimes in rectangular microchannel
Authors: Ronshin Fedor , Dementyev Yuriy , Chinnov Evgeny
Published: December 2020

Existing cooling systems do not fulfil modern requirements for heat removal from high-heat dissipating sources in electronic and microelectronic equipment. When reducing the flat channel thickness, the ratio of the surface to the volume increases inversely to the minimal transverse size of the channel, resulting in high intensity of heat transfer in microsystems. Schlieren and infrared methods serve to determine the main characteristics of a two-phase flow. The characteristics of heat and mass transfer and regimes are studied at various values of the heat flux.
Distribution of ion velocity near an isolated dust particle
Authors: Salnikov M V , Sukhinin G I
Published: December 2020

In the current paper, a numerical model with self-consistent ion velocity distribution function calculated near an isolated dust particle is presented. This dust particle is under the influence of an external electrostatic field. As a result of calculation, ion velocity distribution function along an axis aligned with the external electrostatic field is obtained. The calculated data allows obtaining the set of parameters for which the approximation of the shifted Maxwell distribution function is applicable.
Graphene growth on the textured copper surface
Authors: Smovzh D V , Morozov V S , Kostogrud I A , Boyko E. V. E V
Published: December 2020

The effect of mechanical processing of copper foil on the single-layer graphene growth is studied. The deformation of the foil in the annealed and unannealed state is carried out by rolling between rollers with varying degrees of roughness. It is shown that the formed single-layer graphene coating on the foil deformed in the unannealed state has a larger number of defects, which is associated with the heterogeneity of the copper texture formed upon annealing. In the case of rolling the copper foil after the annealing stage, the quality of graphene coatings only slightly deteriorates in the deformed areas of foil.
Features of formation of a fluid flow flowing into a highly rarefied medium through a capillary
Authors: Yaskin A S , Zarvin A E , Kalyada V V , Dubrovin K A , Khudozhitkov V E
Published: December 2020

Experimental results of investigation of the form and structure of the flow of ethanol and propylene glycol into a highly rarefied medium (vacuum) through a capillary are presented. It is shown that when liquid flows vertically along gravity into a vacuum with a pressure of residual gases significantly less than the pressure of saturated vapors at the outlet temperature, the liquid jet, in contrast to the flow into a dense gas medium, is statistically unstable, subject to bending deformations and explosive spray.
Sound velocity in the vapor phase of the binary mixture R-125 (63.9 wt.%) – R-134a (36.1 wt.%)
Authors: Komarov S G , Stankus S V
Published: December 2020

Using an ultrasonic interferometer method, the sound velocity in gaseous mixture R-125 (63.9 wt. %) - R-134a (36.1 wt. %) was investigated in the temperature interval 303-393 K and pressure up to 0.95 MPa. The temperature measurement error was 20 mK, pressure 4 kPa, and sound velocity (0.2–0.3) %. It was shown that the sound velocity values increase with temperature and decrease with pressure. Comparison of our data with the calculations using the REFPROP software was performed.
Thermal expansion of vanadium in the temperature range of 98–2400 K
Authors: Kozlovskii Yu M , Stankus S V
Published: December 2020

The experimental results of a study of the thermal expansion of polycrystalline vanadium in the temperature range of 98–1723 K are presented. The correlation of the dilatometric data and γ-ray attenuation technique was established. The temperature dependence of thermal properties up to 2400 K was obtained and reference table of recommended values was calculated.
Heat capacity and phase transition of bismuth niobate doped by rare earth elements
Authors: Matskevich N I , Stankus S V , Samoshkin D A , Zaitsev V P , Tkachev E N
Published: December 2020

The heat capacity of bismuth niobate doped by rare earth elements (R = Er, Lu) was measured by differential scanning calorimetry. It was found that there were phase transitions for investigated compounds at temperatures > 500 K. The temperatures of beginning phase transitions increased with decreasing of rare earth elements radii, which correlated with an increase in lattice energies.
Equation of liquid, gas, and fluid state for methane
Authors: Meshalkin A B , Dutova O S
Published: December 2020

Using methods and approaches, previously developed by the authors, a new fundamental low-parametric equation of state for methane (in the form of the reduced Helmholtz function) has obtained to describe the thermodynamic properties. It allows describing the thermal properties of gas, liquid, and fluid at pressures of up to 20 MPa with sufficiently high accuracy close to the experimental one (with the exception of the critical region). The sound speed and caloric properties of methane have been calculated without involving any caloric data, with the exception of ideal gas enthalpy. The values of speed of sound, isochoric heat capacity, and other thermodynamic properties obtained by calculations are in good agreement with the experimental data.
Heat capacity of neodymium- and gadolinium-gallium garnets
Authors: Samoshkin D A , Stankus S V
Published: December 2020

In the present article an experimental study of neodymium- and gadolinium-gallium garnets (NGG and GGG) heat capacity was carried out by the method of differential scanning calorimetry. The measurements were performed in the temperature interval from 300 to 975 K, and the estimated error of the received data was 2–3%. The fitting equations for specific heat temperature dependences have been received. The table of recommended values for investigated gallium garnets heat capacity has been developed for the use in various theoretical and applied problems.
Approaches to simulate destruction of a fuel rod with different fuel types
Authors: Usov E V , Gafiyatullin A R , Klimonov I A , Chuhno V I
Published: December 2020

Due to the revival of interest to the development of fast reactors cooled by liquid metals, the theoretical research for improving their safety is actual. A detailed calculation of all stages of an accident from the beginning to the end requires knowledge of the laws for modelling physical processes occurring in the reactor in case of emergency. The most serious are accidents with core destruction. Simulation of a severe accident in a nuclear reactor is the key element in safety analysis of nuclear power plants. Destruction of fuel rods is one of the most important processes during core degradation that should be calculated. For different types of fuels the mechanisms of the degradation are different too. For example, oxide and metallic fuels usually melt congruently at high temperature, but nitride fuel dissociates. The main objective of the proposed research is to develop models and numerical algorithms for calculation of the destruction of fuel rods with oxide, metallic and nitride fuels. The models of destruction and some calculation results are presented in the paper. The processes are investigated for the first phase of severe accidents, covering the period from the onset of fuel-rod melting to the melt escape from the core center.
Experimental studies of the evolution of non-stationary natural convective boundary layers at different heat flux densities on a vertical wall
Authors: Berdnikov V S , Grishkov V A , Mikhajlov A V
Published: December 2020

The evolution of convective flow in a layer of ethyl alcohol with a free surface after sudden heating of one of the vertical walls of a rectangular cavity is experimentally studied. The evolution of a non-stationary hydrodynamic boundary layer on a heated vertical wall in time is studied using digital video recording and computer processing of video films. The evolution of the flow along the free surface of the liquid layer is investigated. Using a thermal imager, the time evolution of the temperature field on a thin metal vertical wall after the flow of a heated liquid is investigated.
Laser line scanning of a shape of moving objects with various degree of transparency
Authors: Mel’nik A V , Seredkin A V , Tokarev M P , Gobyzov O A
Published: December 2020

Laser scanning methods for surface geometry reconstruction have become a common tool in many areas of application due to relative simplicity, high accuracy, and versatility. Nevertheless, scanning of glossy or translucent surfaces still poses a problem for these techniques. The present work aims at assessing the applicability of the laser line scanning method for evaluation of the height profile of a waste stream on a conveyor belt, taking into account that the waste stream may contain a large number of semi-transparent objects. In particular, preliminary results of height profile measurements with regard to the laser emission wavelength for polyethylene terephthalate (PET) bottles with various degrees of transparency, common in the municipal solid wastes, are reported in the paper.
Unsteady conjugate convective heat transfer in a vertical channel at a sudden heating of the bottom
Authors: Mitin K A , Mitina A V , Berdnikov V S
Published: December 2020

The processes of unsteady heat transfer in the mode of thermogravitational convection in a vertical channel with solid walls of finite thermal conductivity after a sudden heating from bottom was studied numerically by the finite element method in three-dimensional problem statement. The system of thermogravitational convection equations was solved in the Boussinesq approximation in the variables of vortex–vector potential of the velocity field and temperature. The calculations were performed with the Prandtl number of 10, the Grashof number of 5000, and the ratio of the thermal conductivity of solid walls to the thermal conductivity of the liquid equal to 6.29. Distributions of the unsteady temperature field into the liquid and solid walls, temperature gradient fields, and velocity fields in the liquid were obtained. The process of formation, loss of axial symmetry and subsequent development of the rising stream was shown.
Effect of thermal conductivity of thin walls limiting the inclined liquid layer on non-stationary conjugate natural convective heat exchange and temperature fields in thin walls
Authors: Mitin K A , Mitina A V , Berdnikov V S
Published: December 2020

Non-stationary conjugate convective heat transfer in a rectangular cavity at an angle of 45 degrees is studied numerically in the conjugate formulation. A liquid layer with a Prandtl number of 25.66 is located in a cavity with thin metal or low-heat walls. The outer surface of the lower wall is suddenly heated, and the outer surface of the upper wall is maintained at the original temperature. The system of equations of non-stationary thermogravitation convection is solved in the Boussinesq approximation in a dimensionless form. The time evolution of convective flows and temperature fields in the liquid and in the walls is studied. It is shown that the thermal conductivity of walls significantly affects the spatial shape of convective flows and the regularities of conjugated convective heat exchange.
Analysis of Mechanical Design Manufacture and Automation Characteristics, Advantages and Development Trends
Authors: Wei Li
Published: December 2020

Mechanical manufacturing design is an important direction in the field of automation in China which promotes the development of China’s productivity and economy. Based on this, this paper discusses the advantages and trends of automation in mechanical manufacturing so as to improve the efficiency of machinery manufacturing and promote economic development. Therefore, it is hoped that this paper can provide some references for related researchers.