bluuebunny/crossref_metadata_2025 huggingface dataset:
About boundary conditions for kinetic equations in metal
Authors: Karimov F , Lam T N , Yushkanov A A
Published: November 2021

Boundary conditions for kinetic equations describing the dynamics of electrons in the metal were analyzed. The boundary condition of the Fuchs and the boundary condition of Soffer were considered. The Andreev conditions for almost tangential moving electrons were taken into account. It is shown that the Soffer boundary condition does not satisfy this condition. The boundary condition was proposed that satisfies the Andreev condition. It is shown that this boundary condition passes in the limiting case into the mirror–diffuse Fuchs boundary condition.
Longitudinal Plasmons in a Thin Flat Conductive Film
Authors: Zotov A A , Zverev N V
Published: November 2021

The longitudinal plasmons in the plasma of conductivity electrons between the surfaces of a thin flat conductive film are investigated. It is shown that these plasmons lead to a resonant behaviour of the optical power coefficient of E-wave interaction with this film. The conditions for appearance of these plasmon resonances are found, and peculiarities of the dependence of the resonant frequencies on the film characteristics are revealed.
Relaxation type Kinetic equation for electrons in polycrystalline metal
Authors: Lam T N , Karimov F , Yushkanov A A
Published: November 2021

The kinetic equation for electrons in a polycrystalline metal is considered. A kinetic equation is written that describes in a unified manner the scattering of conduction electrons both by impurities or phonons and by grain boundaries. This kinetic equation takes into account the scattering of electrons at the boundaries of crystallites of a polycrystalline metal An expression is obtained for the bulk conductivity in the general case. Let us analyze the effect of electron scattering at grain boundaries on its electrical properties.
MATLAB Modelling electron energy spectrum in one-dimensional quantum well with infinitely high walls for GaAs solid solution
Authors: Kozhanova E R , Tkachenko I M
Published: November 2021

The paper presents calculations of electron states in semiconductor nanostructures AlxGa1–x As (x=0) and simulates the energy spectrum of the electron in a one-dimensional quantum well with infinitely high walls of a given width (from 10 to 30 atomic monolayers) using MATLAB application. The data is visualized using a wavelet transform with different wavelet functions.
Dependence of the integral characteristics of a nematic light modulator on the physical parameters of a liquid crystal
Authors: Simonenko G V
Published: November 2021

In the present work, the effect of physical constants of an LC material on the integral characteristics of a modulator operating in a waveguide mode in an LC structure with a twist angle of 270 and antisymmetric boundary conditions in the working cell was studied using the method of computer simulation. It is shown that, under antisymmetric boundary conditions, the small value of the total response time of the LC modulator is due to the absence of a “backflow” in the LC cell and the role of only half of the LC working gap thickness in the dynamics of switching between two states in such a device. In addition, it was found that in order to simultaneously achieve high contrast ratios and a short total response time of the device, it is necessary to choose an LC material with a high value of its dielectric anisotropy. In this case, there is an optimal set of elasticity constants for the LC material, which simultaneously realizes a high contrast ratio and a short total response time of the modulator.
Mathematical Modeling of Survivability Function for Thermoelectric Module
Authors: Sattar Sh , Osipkov A , Belyaev V V
Published: November 2021

Developing an optimized reliability model for thermoelectric module at the stress where the probability of module to functions without abruptive failure is a challenging aspect. One of the major reasons is the mismatch of thermal expansion coefficient, which has severe effects on segmented moduli compared to unsegmented moduli. The likelihood of a thermoelectric module to survive at certain level of thermo-mechanical stresses varies by varying number of component (layers) in thermoelectric leg. On another hand, selection of an adequate distribution model to predict reliability and sustainability of the thermoelectric module requires development of new optimized stress-strength-based model. In this paper the predictive reliability model for high temperature segmented module is derived from parametric Lognormal mean residual life and nonparametric Lognormal-kernel survival function to measure probability of module to survive at certain thermo-mechanical stress. A comprehensive comparative discussion has been done to illustrate the maximum likelihood based on Bayesian nonparametric lognormal-Kernel inference method regarding to Monte Carlo simulation, Weibull’s distribution, and Lognormal mean residual life for various shapes for the survival function. It has been demonstrated that nonparametric lognormal-kernel survival function has high ratio of probability to predict the survival of module at higher discrete thermo-mechanical stress data.
Optical rotation dispersion of cholesteric-nematic mixture
Authors: Vasilchikova E N , Dmitrieva A D , Kondakova A V , Kurilov A D , Usachev V V , Muravsky A A , Chausov D N
Published: November 2021

The dispersion of the specific rotation constant of a cholesteric-nematic mixture of 5CB and Ch17 at a low concentration was studied by optical spectroscopy. The dispersion of the anisotropy of the refractive index as a function of the wavelength is studied, and the helical pitch of the cholesteric-nematic mixture is calculated.
Special features of short-duration processes in condensed media
Authors: Khantuleva Tatyana A. , Kats Victor M.
Published: November 2021

The problem of the short-duration processes is considered on the base of the nonlocal theory of non-equilibrium transport, taking into account inertial effects. The system temporal evolution out of equilibrium connected to the dynamic structure transition described by the Speed-Gradient principle (SG-principle or SGP) developed in control theory and cybernetic physics. In the manuscript, we show that retardation of the system response to the short-duration loading due to inertial effects influences on the system evolution and can change its direction. The response to the shock loading of condensed matter is compared to quasi-stationary loading in a wide range of conditions. The short duration loading can lead the system into the structure unstable state and even give rise to self-organization of turbulent structures in the medium. The use of SGP for the modelling of such processes opens new possibilities to control them.
The formation of super-long nano-chains during evaporation of metals with a help of intensive impacts
Authors: Klassen N V , Provotorov P V
Published: November 2021

Extended nanostructures, in particular, chains of nanoparticles, are of great interest for microelectronics, biomedicine, and energy. But until now, it was possible to obtain such structures with the lengths not more than a few millimeters. We have developed several techniques based on laser and electric evaporation of metals, which provide the formation of nanochains with the lengths up to 60 cm. A significant factor in the formation of such structures is the constructive participation of turbulent vortices, which create the necessary compression and subsequent agglomeration of the vapors of metals and oxides subjected to the intensive electrical or laser impacts. Research and production of the nano-structures with large surfaces and lengths provide promising opportunities for the direct converters of solar energy and ionizing radiation to electricity, development of new optoelectronic and microelectronic devices as well as highly sensitive biosensors.
Giant spin-valve effect in Al/Y3Fe5O12 heterostructures
Authors: Skryabina O V , Uspenskaya L S
Published: November 2021

Superconducting phase transition in the aluminium stripes fabricated on yttrium-iron garnet and on oxidized silicon substrates is studied. Reduction of critical temperature, widening of superconducting transition depending upon the mutual current and magnetization orientations as well as on current strength are observed in aluminium on garnet comparing with aluminium on silicon. The proximity and triplet proximity effects, Andreev reflection, exchange interaction, spin-orbit coupling and self YIG magnetic field impacts on the observed effects are discussed. We show that only accounting for the spin-orbit coupling and self-magnetic field of YIG is allowed to explain the observed phenomenon of asymmetric change in the transition under the variation of the current and magnetization alignment. Based on the obtained results, we suggest a new geometry of spin-valve with hundreds percent variation of the resistance controlled by the current.
The concept of biaxial surface potential and polymer aligning layers in electro-optical cells based on helical nanostructures of ferroelectric liquid crystal
Authors: Tkachenko T P , Zhukov A A , Pozhidaev E P
Published: November 2021

The paper considers the possibility of controlling the alignment quality of helical nanostructures of ferroelectric liquid crystals (FLCs) within the concept of biaxial surface potential due to variation the FLCs helical pitch p0
and polymer aligning layers structures.
Influence of the temperature field in the energy-saving carbon-graphite thermal unit on configuration of the solidification front under different conditions of growing fluoride single crystals by the HDS method
Authors: Yusim V A , Sarkisov S E , Kloss Y Y , Yusim F A , Ivanova L V
Published: November 2021

Mathematical modeling of the influence of the temperature field created by the ECU on the position and on configuration of the solidification front under different conditions of growing single crystals of fluorides by the HDS method has been carried out. Data were obtained for different growing conditions for single crystals of fluorides and their effect on configuration of the solidification front in various modifications of the ECU of the first and second types. From a comparison of mathematical calculations, a conclusion was made about the most suitable conditions for the synthesis of these single crystals.
Advanced processes for low-temperature formation of functional metal oxide based thin films
Authors: Abduev A , Akhmedov A , Asvarov A , Kanevsky V , Muslimov A , Belyaev V , Generalov D , Nikolaeva D , Tirado J , Frah M A A
Published: November 2021

The analysis the discharge processes in magnetron plasma, target sputtering processes, as well as nucleation and formation of oxide thin films during dc magnetron sputtering is carried out. Particular attention is paid to the phenomenon of instabilities of the current-voltage characteristics of magnetron plasma during the sputtering of oxide targets, the processes of structural transformations of the surface of metal oxide targets under ion bombardment impact, and the mechanisms of low-temperature magnetron deposition of metal oxide thin films. Based on the results of the analysis performed the optimal routes for improving technologies for the low-temperature formation of transparent conductive oxide thin films have been discussed.
Synthesis of ZnS:Cu,Br radioluminescent phosphors using the electron-beam treatment and studying their characteristics
Authors: Bakhmetyev V V , Zelenina E V , Shvindin M A
Published: November 2021

ZnS:Cu radioluminescent phosphors find their applications in medicine nondestructive testing, safety control and can be used as a part of the solid-state radioluminescent light sources (SRLS). This devices are very promising technology due to their independence longevity and safety compared to the gas-filled RLS. Because of the fact that tritium (the most popular radioisotope for RLS) has a very short range in substances, the improving the operating performances of radiophosphors is a crucial task for SRLS. In our study we used the electron-beam treatment to increase the brightness of radioluminescence of ZnS:Cu phosphors. It was found that bombardment of the phosphors initial charge with electrons of 900 kEv energy improves the brightness of radioluminescence by 15 – 20%. Double modifying of the initial charge and ready phosphor cause the 80% increase of brightness. The effect of electron-beam treatment on the phase content and the surface properties was studied at varying the content of activator (Cu) in the range of 0 – 0.6 % mass. As a result the model describing structure of the acid-base sites on the ZnS:Cu phosphor surface was suggested.
Formulation of the modern indicator devices modelling problem
Authors: Buzaeva E A , Evsevichev D A , Maksimova O V
Published: November 2021

This work is dedicated to study of the structural characteristics and parameters in advanced electroluminescent structures. The important problems in this area are the high complexity and the slowness of the design calculation processes. The problem can be solved by developing a mathematical model of the system based on equivalent circuits. First step in developing a mathematical model is formulation.
Improving the performance of the air-cooling unit in the cooling system of a radar
Authors: Borisov Yu A , Volkov-Muzilev V V , Kalashnikov D A , Khalife H S
Published: November 2021

The article discusses the issues of reducing the size of the cooling unit of the antenna of a radar station by improving the gas-dynamic processes occurring in the air-cooling unit. The results of the experimental studies of the gas flow in a plate-fin heat exchanger, being blown by one axial fan are presented. The feasibility of changing the number of axial fans for organizing a more uniform flow around the heat-exchange surfaces has been determined by calculation and theoretical methods. The calculation results are confirmed by experimental studies of the air flow in the segment of the heat exchanger, which is provided by a smaller fan.
Modeling the working media flow in shut-off valves with displacement of the regulating body perpendicular to the flow axis
Authors: Soloveva V V , Pugachuk A S , Chernyschev A V
Published: November 2021

The mathematical model of the working fluid movement in the flow section of the wedge type two-disc parallel gate valve is developed. The simulation of the fluid flow through the valve cavity is carried out, as a result the flow parameters are obtained in a wide range of Reynolds numbers at the entrance to the calculated area. The dependence of the hydraulic resistance as a function of the Reynolds number for liquid and gas flow is calculated. The various positions of the shut-off body in the flow part of the valve are considered and the area of reduced pressures in which the effect of cavitation may occur during fluid flow is estimated.
Application of the video correlation method to measure the velocity on the surface of a liquid metal
Authors: Teplyakov I O , Vinogradov D A , Klementyeva I B , Ivochkin Yu P
Published: November 2021

In this work, the applicability of the video correlation method proposed by the authors for measuring the velocity on the surface of a liquid metal in an electrovortex flow in a hemisphere is investigated. The method is based on calculating the cross-correlation of the brightness signals of two closely spaced points in the video. It is shown that the method allows quite simply determining the velocity of the liquid metal.
Eddy generation and variability of the marginal ice zone in the Fram Strait according to satellite radar measurements
Authors: Petrenko L A , Kozlov I E
Published: November 2021

Based on analysis of spaceborne synthetic aperture data (SAR), acquired in summer of 2007 over Fram Strait and around Svalbard, we investigate spatial and temporal variability of the ice edge and generation of eddies in the marginal ice zone. During the season, the ice-water boundary nonuniformly moves along its entire length with the overall width of the ice edge displacement ranging from 30 to 220 km. The ice edge movement is often accompanied by generation of eddies and filaments peaking in August. Analysis of the data serves to find out over 2000 distinct MIZ eddies with a clear dominance of cyclones (78%). In July the detected eddies are predominantly formed along the ice edge, in August most of them are generated inside the MIZ, while in September their numbers along the ice edge and within the MIZ are similar. Larger eddies (10-20 km in diameter) are found over deep Fram Strait and the Greenland Sea shelf, while smaller eddies (~5 km) are observed in coastal regions around Svalbard.
Application of the time-frequency technique for analysis of velocity fluctuations in the wake of a teardrop profile in the presence of a localized flow inhomogeneity
Authors: Mironov D S , Lebiga V A , Zinoviev V N , Pak A Yu
Published: November 2021

Experimental simulation of the inhomogeneity of the incident flow localized in time and space on a bluff tear-drop airfoil is carried out. It is shown that in the region outside the aerodynamic wake of the tear-drop airfoil, the presence of inhomogeneity leads to an increase in the amplitudes of velocity fluctuations in a wide frequency range. In the region inside the wake, the presence of inhomogeneity leads to the suppression of velocity fluctuations at the frequency of vortex shedding by a factor of 2–3 in amplitude. The intensification of fluctuations at frequencies above the main one was also noted, and there was no effect on fluctuations at lower frequencies.
Reflection of sound pulses from an inhomogeneous bubble medium
Authors: Ogorodnikov I A
Published: November 2021

The effect of changes in the volume concentration of bubbles in the boundary zone of the bubble medium on the nature of reflection and radiation of the excited bubble medium is studied. The spectral characteristics of the radiation of a bubble medium are obtained at the initial stage of transition radiation and at large times when the radiation is stationary. It is shown that in the initial phase the emission spectrum is broadband and is located in the absorption band of the bubble medium, and at large times the emission spectrum is located outside this band.
Unsteady cavities near the hydrofoil with a small aspect ratio
Authors: Skripkin S G , Tsoy M A , Kravtsova A Y
Published: November 2021

Using digital processing of high-speed visualization data on a cavitation flow near NACA hydrofoil with critically low aspect ratio, the frequencies of the formation and separation of cavities in the flow are identified. It is shown that in the case of development of cloud cavitation the main dimensionless frequency varies within 0.4, which corresponds to the type of internal instability. The Strouhal number corresponds to the frequency of attached cavity occurrence and varies in range from 0.6 to 0.8. The Strouhal numbers calculated in third mode exceed 1. This mode corresponds to the forming of very small cavities near the leading edge of hydrofoil.
Collision of water drops with a thin cylinder
Authors: Fedyushkin A I , Rozhkov A N , Rudenko A O
Published: November 2021

The collision of water drops with a thin cylinder is studied. The droplet flight trajectory and the cylinder axis are mutually perpendicular. In the experiments, the drop diameter is 3 mm, and the diameter of horizontal stainless-steel cylinders is 0.4 and 0.8 mm. The drops are formed by a liquid slowly pumped through a vertical stainless-steel capillary with an outer diameter of 0.8 mm, from which droplets are periodically separated under the action of gravity. The droplet velocity before collision is defined by the distance between the capillary cut and the target (cylinder); in experiments, this distance is approximately 5, 10, and 20 mm. The drop velocities before the impact are estimated in the range of 0.2–0.5 m/s. The collision process is monitored by high-speed video recording methods with a frame rate of 240 and 960 Hz. The test liquids are water. Experiments and numerical simulation show that, depending on the drop impact height (droplets velocity) different scenarios of a drop collision with a thin cylinder are possible: a short-term recoil of a drop from an obstacle, a drop flowing around a cylindrical obstacle while maintaining the continuity of the drop, the breakup of a drop into two secondary drops, one of which can continue flight and the other one is captured by the cylinder, or both secondary droplets continue to fly, and the drop can be also captured by the cylinder, until the impact of the next drop(s) forces the accumulated drop to detach from the cylinder. Numerical modeling satisfactorily reproduces the phenomena observed in the experiment.
Measurements of pitch-off diameter of gas bubbles in liquid metal
Authors: Lobanov P D , Pribaturin N A , Svetonosov A I
Published: November 2021

To determine the separation diameter of bubbles in a liquid metal melt, an original technique based on the conductivity method is proposed. A thin electrode is installed in the center of the outflow channel, and the separation of bubbles is determined by closing and opening the electrical circuit. In this way, the separation frequency of the bubbles and their volume can be determined. Additional studies are carried out on a transparent liquid (water). It is shown that the presence of an electrode has little effect on the process of bubble detachment. The processing data of high-speed video filming and the proposed method in a transparent liquid coincide with high accuracy. Measurements of the frequency of bubble detachment in melts of the Rose and lead alloy are carried out. The results obtained are used to tune two-phase flow models when simulating fast neutron reactors with heavy liquid metal coolants.
Influence of channel to heater width ratio on flow boiling critical heat flux in mini- and microchannels
Authors: Zaitsev D V , Belosludtsev V V
Published: November 2021

Flow boiling experiments were conducted in mini- and microchannel with different ratio of heater width to a channel width. Decrease in critical heat flux is observed in transition from wide channel to channel with width equal to a heater width. Particularities of boiling phenomena in these conditions were observed by means of high-speed visualization, which provided an explanation to heat flux reduction.
Modeling of thermodynamic processes using the properties of matter presented in the form of spreadsheets
Authors: Ramazanov E R , Kosoy A A
Published: November 2021

New thermodynamic cycles are developed in which the working fluid used cannot be considered as an ideal gas. This applies to oxy-fuel combustion cycles. In these cycles, oxygen is separated from the air prior to combustion. The combustion chamber is supplied with fuel and pure oxygen. The required temperature at the outlet of the combustion chamber is achieved by supplying some other substances from which it is easy to separate the CO2 formed during the combustion of the fuel. Commonly, CO2, or H2O, or their mixture is used as such substances. Thus, there are no exotic substances in the composition of the working fluid, but such a range of parameters is chosen for such cycles that the working fluid at certain points of the cycle can be both gaseous and liquid, or in a supercritical state. To model thermodynamic processes in such cycles, it is unacceptable to use the polytropic equation of ideal gases. A technique for integrating differential equations describing the state of the working fluid is proposed. This technique is based on the presentation of the thermodynamic properties of pure substances that make up the working fluid in the form of spreadsheets. The proposed technique is implemented in a software-computing module.
Boiling of He-II on a cylindrical heater inside a porous shell with constant operation condition
Authors: Korolyov P V , Yachevsky I A , Volodin I V
Published: November 2021

This paper presents new efforts undertaken in the study of boiling in superfluid helium on the surface of a cylindrical heater located along the axis in a cylindrical cavity inside a porous shell. New experimental results are obtained with maintaining constant temperature of the helium-II and helium vapor pressure. The modernization of the experimental setup and vacuum system carried out to obtain a series of longer experiments with maintaining a stationary state are described. The basic experimental configurations are specified. Visualization of helium-II film boiling in constant operation condition is represented.
Experimental study of evaporation of droplets of water ethanol solution at high relative air humidity
Authors: Sterlyagov A N , Nizovtsev M I , Letushko V N
Published: November 2021

A change in the temperature of suspended droplets of a water solution of ethanol, evaporating at high relative humidity, is experimentally investigated using high-speed microphotography and infrared thermography. The data obtained for ethyl alcohol droplets show a significant dependence of the surface temperature of evaporating droplets on relative humidity of the ambient air. It should be noted that at high relative humidity, a significantly smaller decrease in the temperature of droplet surface than at low humidity was observed during evaporation. This relates to the processes of moisture absorption and condensation on the surface of an evaporating droplet of ethyl alcohol at high air humidity, accompanied by the release of heat.
Effect of boron on HEM radiant ignition characteristics
Authors: Korotkikh A G , Sorokin I V
Published: November 2021

The paper presents the ignition characteristics of high-energy materials (HEMs) containing ammonium perchlorate, butadiene rubber, and a mixture of Al/B nanopowders with different component ratios. Bimetallic systems based on aluminum with boron increase the reactivity and intensify the ignition of boron particles, which helps to decrease the critical ignition conditions of HEMs during heating. It is shown that the use of systems based on aluminum-boron reduces the delay time (by 17–52 %) and the ignition temperature of propellants in comparison with a HEM containing aluminum powder, and increases the activation energy of HEM during radiant heating.
Numerical determination of the combustion rate of a gas suspension of coal dust in a propane-air mixture
Authors: Moiseeva K M , Krainov A Yu , Kantarbaeva A
Published: November 2021

The results of the numerical solution of the problem of the combustion rate of a coal-propane-air mixture are presented. The physical and mathematical formulation of the problem is based on the approaches of the dynamics of multiphase reacting media. The method for solving the problem is based on the algorithm for the decay of an arbitrary discontinuity. The dependences of the visible and normal combustion rate of the coal-propane-air mixture on the radius and the volumetric content of propane in the gas are obtained.
Numerical study of continuously rotating detonation in two-fuel gaseous mixture
Authors: Trotsyuk A V
Published: November 2021

Numerical simulation of continuously rotating detonations of stoichiometric two-fuel mixture with air has been carried out for the cylindrical annular detonation chamber (DC) of the rocket-type engine. The syngas (1-α)СO+αH2, a binary mixture of hydrogen H2 and carbon monoxide CO, is taken. We studied the global flow structure in DC, and the detailed structure of the transverse wave (TW) front in the continuous rotating regime. Integral characteristics of the detonation process − the distribution of average values of static and total pressure along the length of the DC, and the value of specific impulse have been obtained. The region of existence of stable continuous detonation regime in coordinates of the stagnation pressure - temperature in injection manifold (receiver) and the geometric limit of stable TW have been determined.
Estimating the applicability of kinetic schemes in hydrogen combustion simulation in combustion chambers of aircraft engines
Authors: Sokolova E I , Studennikov E S , Chelebyan O G
Published: November 2021

This paper presents the results of numerical simulation of hydrogen combustion in a supersonic flow of an oxidizing medium in a model combustion chamber using various models of chemical kinetics. The best scheme, which most accurately describes the combustion processes, is revealed. Comparison of the calculated distribution of molar fractions with experimental data is carried out, and relative deviations for the piloted mode of operation of the chamber are obtained.
Development of a mathematical model of diesel-generator units with a valve-inductor generator
Authors: Zhigarev V A , Minakov A V , Guzei D V , Pryazhnikov M I , Panteleev V I
Published: November 2021

The paper presents a comprehensive mathematical model of a diesel-generator units with a valve-inductor generator. The calculated data obtained using this model allows optimizing the operation of fuel injectors and adjust the injection characteristics. The electromagnetic part of the model allows taking into account the power losses and efficiency of the generator, calculating the phase windings and their connection schemes, methods for setting the voltage or current of any shape that feeds the windings of the valve-inductor generator, as well as the characteristics of the rotor, stator, and winding materials to obtain the most effective operation parameters of the engine in various operating modes as part of the generator unit.
Validation of a laminar-turbulent transition prediction technique for a swept-wing boundary-layer flow
Authors: Boiko A V , Borodulin V I , Ivanov A V , Kirilovskiy S V , Mischenko D A , Poplavskaya T V
Published: November 2021

The laminar-turbulent transition in the boundary layer of a 45° swept wing model installed at zero attack angle in the test section of a subsonic wind-tunnel was detected with the help of an infrared camera. The camera recorded sequences of frames, the evolution of the preheated model surface temperature acquired and used for differentiating between the laminar and turbulent regions. The transition onset was evaluated at both sides of the model. Corresponding main flow computations in the virtual wind tunnel test section were performed at the same flow conditions with ANSYS Fluent. The computed main-flow velocity profiles along inviscid streamlines were used for analysis of hydrodynamic stability of the boundary layer with respect to Tollmien-Schlichting waves and stationary cross-flow vortices to obtain N-factor distributions along the model chord. A comparison of the experimental and the computed transition onsets was performed.
Hydrodynamic simulation of laser-induced shock waves using the Turbulence Problem Solver software package
Authors: Shepelev V V , Fortova S V
Published: November 2021

The problem of irradiation of a semi-infinite bulk metal target by a single laser pulse, being important for many lase technology applications, is considered. The model for simulating the propagation and attenuation of shock waves, occurring when metals are irradiated with single laser pulse, is presented. The paper describes the computational algorithm based on the model and features of its implementation in C++ in a software package Turbulence Problem Solver (TPS) for modeling a wide class of problems described by hyperbolic equations. The problem is modeled using different approaches and the results are compared. The object-oriented polymorphic architecture of the software complex accelerates and facilitates the process of model development and calibration, allowing for flexible configuration and combination of elements of numerical models: Riemann solvers, various types of and reconstructions, and equations of state of matter.
Estimation of the turbulent Schmidt number in a model gas turbine combustor
Authors: Savitskii A G , Sharaborin D K , Lobasov A S , Dulin V M
Published: November 2021

This article presents the estimation of turbulent Schmidt number in a model gas turbine combustor. Different gases are used as the model fuel while maintaining the mass flow rate. The simplest closure models for Reynolds stress and turbulent flux are considered. The anisotropy of turbulent viscosity is demonstrated.
Measuring the diameter of a cylinder with automatic calibration
Authors: Dvoynishnikov S V , Bakakin G V , Meledin V G , Rahmanov V V , Sadbakov O Yu
Published: November 2021

The work aims at developing a method for measuring the diameter of cylindrical objects, eliminating the need for calibration and verification of the measurement system during operation. The system for measuring the diameter of cylindrical objects contains a photodetector and a light source located on opposite sides of the measured object to implement the shadow method. The proposed method is based on the measurement of two reference cylinders located in the measuring area for automatic calibration of the system at each measurement. It is shown that the proposed method provides stable reliable measurements with an error of less than 2 μm for the diameter of the measured cylindrical objects of up to 10 mm.
A software and hardware system for synchronous control of the optical system for visual control of dynamic objects
Authors: Semenov D O , Dvoynishnikov S V , Kulikov D V , Meledin V G , Chybov A S
Published: November 2021

This work deals with the development of the software for the system of synchronous control of the optical system of visual control over dynamic objects and the creation of algorithms for resolving conflicts of simultaneous illumination by several light sources. The software for the microcontroller for the system hardware is created as part of the work. An application for remote configuration of the device is developed. Algorithms for time-separation of signals for switching on lighting are implemented.
Developing the software and hardware complex to diagnose the ascent of gas bubbles in a liquid metal by the Doppler anemometry method
Authors: Strelnik A S , Dvoinishnikov S V , Meledin V G , Rahmanov V V , Bakakin G V , Kabardin I K , Kabardin A K
Published: November 2021

The complex method of ultrasonic diagnostics of two-phase flows in a liquid metal medium is developed. It allows measuring the dynamic and structural characteristics of the floating inhomogeneity. A software and hardware complex that implements the proposed method is developed and tested for ultrasonic diagnostics of two-phase flows in water and liquid metal medium.
The effect of model material properties on thermal imaging measurements
Authors: Kutepova A I , Polivanov P A , Sidorenko A A
Published: November 2021

The temperature distributions arising on the surface of the solid model are investigated. A flow with a shock wave and laminar boundary layer interaction is considered as the main flow. Calculations of the conjugate problem are performed based on RANS approach. The investigated cases correspond to homogeneous material of the solid model and the model consisting of two materials with different thermal conductivity. In this study, the model designs are found to obtain a temperature distribution suitable for thermal imaging measurements. In addition, in the calculations, the effect of forced heating of the model wall on the temperature distribution is investigated.
Correlation analysis for the research of local characteristics of a turbulent flow
Authors: Sardov P A , Belyaev I A , Listratov Ya I , Razuvanov N G
Published: November 2021

The paper describes the temperature-correlation velocimetry technique applied to the flow of water or liquid metal. The method allows simultaneous measurement of temperature signals and local values of a longitudinal velocity component in the flow. This approach is a simple and reliable method for measuring velocity in flows of optically impermeable fluids. At the same flow conditions, different coolants have different spatial-temporal characteristics that are processed using a temperature-correlation technique. This work is devoted to the development of an algorithm for formulating a set of practical recommendations for the use of this technique to measure velocity and to determine a metrological characteristic in various conditions. For calibration, water and mercury are used as model liquids. The data obtained are presented in the form of fields of temperature and intensity of temperature fluctuations. Autocorrelation and cross-correlation functions are compared for two investigated liquids under the same conditions.
Convection in an evaporating drop of aqueous solution at a high concentration of microscopic particles
Authors: Misyura S Y , Bilsky A V , Gobyzov O A , Ryabov M N , Morozov V S
Published: November 2021

This article presents the performed experimental studies on the effect of the concentration of microparticles on free convection in a water drop located on a heated smooth and textured wall surface. It is shown that at a high concentration of particles, their aggregation and deposition take place on the wall and on the free surface of droplet. As a result, the average convection velocity in the droplet decreases significantly. Suppression of convection is important to consider when simulating heat transfer and droplet evaporation. The results obtained are important for technologies that use colloidal solutions (drops, films).
Experimental study of the thermophysical properties for aluminum-magnesium alloy AMg3
Authors: Agazhanov A Sh , Samoshkin D A , Kozlovskii Yu M , Stankus S V
Published: November 2021

The thermal diffusivity (a), the thermal coefficient of linear expansion (α), the isobaric heat capacity (cp
) and the fusion enthalpy (ΔH) of aluminum-magnesium alloy AMg3 were investigated by laser flash method, dilatometric method and method of differential scanning calorimetry in the temperature range of 300–773…1000 K. The thermal conductivity (λ) has been calculated from the measurement results. The estimated errors of the obtained data were 2–5%, 3–5%, 2–3% and (1.5–2.0)⋅10-7 K-1 for a, λ, cp
and α, respectively. Approximation equations and a table of reference values for the temperature dependence of the studied properties have been obtained.
Optical pulses in carbon nanotubes with strong electron-electron interaction due to impurities
Authors: Konobeeva N N , Belonenko M B
Published: November 2021

In this paper, we investigate electromagnetic pulse propagation in a medium with impurity carbon nanotubes, which are associated with the acoustic subsystem. The electron spectrum for the carbon system is obtained from the model that takes into account Coulomb impurities. Based on the Maxwell's and the wave equations for the vector of the medium displacements, we obtain the effective equations for the vector potential of the electromagnetic field and the component of the displacement vector of the medium. The dependence of the pulse shape on the various system parameters is analyzed.
Density and speed of sound in refrigerant vapor R-125 (31 wt. %) + R-134A (69 wt. %)
Authors: Komarov S G , Stankus S V
Published: November 2021

Using a constant volume piezometer and ultrasonic interferometer methods, the density and speed of sound in gaseous mixture R-125 (31 wt. %) + R-134a (69 wt. %) were measured within the temperature range from 293 to 393 K and at pressure from 0.18…0.47 to 2.5 MPa. The errors in the measuring temperature, pressure, density and speed of sound were ±20 mK, ±4 kPa, ± (0.15–0.3) %, ± (0.1–0.2) %, respectively. It was shown that the speed of sound values increase with temperature and decrease with pressure. The obtained results were compared with the calculations using the REFPROP software.
Hydrodynamic approach to the processing of core sample tests considering microstructural changes
Authors: Kravchenko M N , Ivlev M I , Dieva N N
Published: November 2021

In this paper, authors propose a method to create a complete hydrodynamic model of the polymer displacement process. It is based on the processing of the laboratory tests with core samples, considering the polymer substance properties and microstructural changes occurring in the porous matrix during the adsorption of polymer particles. Based on the adaptation of the mathematical model to the results of tests with polyacrylamide Flopaam and polysaccharide Gum Arabic, calculations of the effectiveness of polymer flooding application on samples of terrigenous deposits are carried out.
Description of the liquid-vapor phase equilibrium line of pure substances within the bounds of scale theory based on the Clapeyron equation
Authors: Rykov S V , Kudryavtseva I V , Rykov V A , Ustyuzhanin E E
Published: November 2021

On the basis of the Clapeyron equation and the scale theory, expressions are developed for the “apparent” heat of vaporization r
* = r
* (T), vapor ρ- = ρ- (T) and liquid ρ+ = ρ+ (T) branches of the saturation line of individual substances for the range of state parameters from the triple point (pt,Tt,ρt
) to the critical (pc,Tc,ρc
). The peculiarity of the proposed approach to the description of the saturation line is that all exponents of the components of the equations ρ- = ρ- (T) and ρ+ = ρ+ (T) are universal up to the universality of the critical indices α, β and Δ. In this case, the order parameter ds
= (ρ+ − ρ-)/(2ρc) and the average diameter df
= (ρ+ + ρ-)/(2ρc) − 1 of the saturation line satisfy the saturation line model [2β,1−α], which follows from the modern theory of critical phenomena. The method is tested on the example of describing the phase equilibrium line of refrigerant R1233zd(E) in the range from Tt
= 195.15 K to Tc
= 439.57 K. It is found that in the temperature range [Tt,Tc
], the developed system of the mutually consistent equations ps
= ps
(T), r
* = r
* (T), ρ- = ρ- (T) and ρ+ = ρ+ (T) allows describing the data on the saturated vapor pressure ps
and densities ρ- and ρ+ on the saturation line within the experimental uncertainty of these data.
Simulating diffusion in the conditions of vapor-liquid phase transition by the molecular dynamics method
Authors: Kharlamov G V
Published: November 2021

The molecular dynamics calculations of diffusion coefficients in binary Lennard-Jones systems have been carried out. The parameters of Lennard-Jones potentials correspond to argon and krypton atoms. The universal dependence of the reduced diffusion coefficient of krypton atoms on density for the homogeneous systems of low and middle densities is found. The deviations of the diffusion coefficients from the universal function are observed for the systems in the vapor – liquid phase transition region. The simulations have shown that almost all krypton atoms have situated inside the liquid phase of argon. Special numerical experiments have shown that the nanodroplets of argon are formed as a result of homogeneous nucleation and then the krypton atoms are captured by these droplets. This phenomenon decreases the diffusion coefficient of krypton atoms greatly.
Comparing the methods of copper substrate polishing for CVD graphene synthesis
Authors: Kostogrud I A , Boyko E V , Matochkin P E , Sorokin D V
Published: November 2021

This paper presents a comparison of chemical and plasma electrolyte polishing methods for preparing a copper substrate for graphene synthesis by chemical vapour deposition. It is shown that in order to achieve the most uniform morphology of the surface of the copper substrate, it is preferable to use the electrolyte-plasma polishing method. With its help, the proportion of multilayer regions in the graphene coating obtained as a result of CVD synthesis decreases. The obtained results may serve a recommendation for creating a graphene coating with specified parameters.
Thermal regime of the local working zone in the industrial premises under radiant heating conditions
Authors: Kuznetsov G V , Maksimov V I , Nagornova T A , Vyatkin A V
Published: November 2021

The results of experimental studies on recording temperatures and heat fluxes for the local working zone in industrial premises under radiant heating conditions and supply and exhaust ventilation operation are presented. The characteristics are measured on the surface of the horizontal remote panel directly under the radiator and along the wall with the ventilation inlet. Experimental results show that mixed convection caused by the operation of air exchange systems leads to mixing of air masses and more intensive cooling of the horizontal panel surface, as well as air, compared to the natural convection regime.
Criterion of drop fragmentation at a collision with a solid target (numerical simulation and experiment)
Authors: Fedyushkin A I , Rozhkov A N
Published: November 2021

This paper is devoted to the study of the deformation and fragmentation of liquid droplets when they collide with masks and filters used for protection against infected droplets. In this paper, the local collision of a drop with a mask or filter is modeled numerically and experimentally by the example of the drop impact on a small obstacle. Studies allow tracing the fragmentation of oral and bronchial fluids and their transformation into the number of tiny droplets that spread infection in the air.
A comparative analysis of schemes of indirect evaporation type apparatuses
Authors: Gorbachev M , Terekhov V
Published: November 2021

In this paper, a comparative analysis of schemes of heat and mass transfer devices of indirect evaporation type is carried out. These devices are a family of plane-parallel channels, in one of which the evaporation of water film takes place. Mathematical modeling of heat and mass transfer devices is based on solving a system of differential equations that represent the heat balance equations for each of the channels. Numerical studies are carried out in a wide range of input parameters: temperature t0 = 15÷50°C, relative air humidity ϕ0 = 20÷100%, and Reynolds number Re = 50÷1500. The assumed geometric dimensions of the channels are height H = 6 mm and length L 50H. The calculations are carried out at atmospheric pressure.
The influence of landscape and urban development on modeling of transport of pollutants in Krasnoyarsk city
Authors: Filimonov S A , Meshkova V D , Dekterev A A , Gavrilov A A , Litvintsev K Yu , Shebelev S V
Published: November 2021

The paper presents the numerical simulation of the distribution of pollutants in winter in the atmosphere of Krasnoyarsk city. The source of the pollution is the suburban areas of the city of Krasnoyarsk, in which coal stove heating prevails. A micro-scale mathematical model based on the solution of the system of non-stationary Reynolds equations is used for modeling. The influence of various factors, such as elements of terrain and urban development, on the distribution of pollutants is studied in the paper.
Compliance Current-dependent Dual-functional Unipolar and Threshold Resistive Switching in Silver Nanowires-egg Albumen Composites-based Device
Authors: Weng Z J , Zhao Z W , Jiang H L , Fang Y
Published: November 2021

The continued exploration of novel synthetic memristive materials with multifunctional properties is critical for future synapse-emulating circuits and electronic devices in the field of next-generation neuromorphic computing applications. In this work, the silver nanowires (AgNWs)-Egg albumen composites have been integrated as a resistive switching layer in the Ag/AgNWs-Egg albumen/Ag planar structure and exhibits both unipolar (memory) switching and threshold switching functions. The device in unipolar switching regime demonstrates an ON/OFF ratio above 105, a low resistance state of about 1.2 KΩ and a high resistance state of about 120 MΩ. Finally, a mechanism in combination with the conductive filament theory and a tunnelling conduction mechanism is proposed to explain the resistive switching behavior. The devices are prepared by simple and low-cost techniques, which make such devices appealing for future electronic applications.