bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical modelling of melt droplet interaction with water
Authors: Yakush S E , Sivakov N S , Melikhov V I , Melikhov O I 
Published: November 2021

Abstract
A collapse of the vapour film separating a hot melt droplet from the surrounding water due to sudden ambient pressure rise is considered. The pressure peak causes a direct contact between water and melt, leading to significant disturbances of the melt droplet surface. Results of numerical simulations performed by the VOF method are presented. Parametric analysis of the interaction process is performed for a molten tin droplet with initial temperature of 950 K, immersed in subcooled water having the temperature of 353 K. The interaction is initiated by sudden rise of the ambient pressure to as much as 8 MPa, imitating the arrival of a thermal detonation wave, with its gradual decrease towards the initial pressure of 0.1 MPa. Simulations reveal the collapse of the vapour film, impingement of water on the droplet surface, and subsequent expansion of vapour due to rapid water evaporation. Significant disturbances of the melt droplet surface are obtained, and implications for the steam explosion problem are discussed.
Prospects for using two-phase micro-size systems for high heat flux removal
Authors: Kuznetsov V V , Shamirzaev A S , Mordovskoy A S 
Published: November 2021

Abstract
Heat transfer in active systems for high heat removal based on the micro-channels and hybrid micro-channel/micro-jet is considered. The application of these systems allows significantly increasing the critical heat flux for a dense arrangement of the heat stressed equipment. The characteristics of heat transfer and critical heat flux during subcooled flow boiling of water in the micro-channel heat sink and during micro-jet impingement in narrow channel are obtained. The experiments are performed for the horizontal segmented microchannels with a cross section of 340×2000 μm2 made on the top of copper target and for impingement micro-jet cooling of the copper target in the gap of 1000 μm. It has been found that, compared with impingement micro-jet cooling in similar condition, the micro-channel cooling is more effective for high heat flux removal although it creates the considerably high wall temperature.
Evaporation of aqueous solution of ethanol into an accelerated laminar boundary layer of air
Authors: Makarov M S , Makarova S N 
Published: November 2021

Abstract
The results of numerical studies of heat and mass transfer during adiabatic evaporation of an aqueous solution of ethanol into an accelerated steam-air laminar boundary layer on a flat wetted plate are presented. The flow acceleration is realized due to the inclination of the upper channel wall, which ensures the constancy of the Kays acceleration parameter. The dependences of the evaporation intensity of the components of solutions of various compositions are obtained for the acceleration parameter 0 and 10-6 for the flow temperature from 20 to 50 °C. A significant effect of the accelerating pressure gradient on the evaporation intensity and its weak effect on the equilibrium wall temperature are shown.
Numerical modelling of agglomeration process in a granular bed containing melting particles
Authors: Donskoy I G 
Published: November 2021

Abstract
The paper considers a numerical model of a flow in a porous medium containing particles of a melting component (polymer). For this, an implicit numerical method of splitting in directions is used. Calculations are carried out for two heating methods (through the side wall, or by the input gas). The simulation results qualitatively reproduce some of the experimentally observed features of the thermal decomposition of polymer-containing mixtures. The results obtained are of interest in the study of low-grade fuels processing, often accompanied by agglomeration, as well as in the development of methods by which agglomeration can be prevented.
The influence of friction on gas parameters in the minimum section of nozzles
Authors: Okhotin V S , Dzhuraeva E V 
Published: November 2021

Abstract
Processes of gas flow in nozzles, accompanied by the release of frictional heat, are presented in the form of polytropic processes. The polytropic process index n determines the degree of irreversibility of the gas flow process caused by the release of frictional heating. Relations are obtained to calculate the flow rate and thermodynamic properties of gas in the minimum section of the Laval nozzle and in the outlet section of the convergent nozzle at a pressure behind the nozzle less than the critical pressure. The gas calculated parameters (pressure, temperature, specific volume, velocity, cross-sectional area) in the minimum cross-section differ from the recommended values in the reference literature [1]. In particular, the gas pressure in the minimum cross section turns out to be higher than the critical pressure recommended in [1].
An evaporation flux of pure vapor in the method of lattice Boltzmann equations
Authors: Kupershtokh A L 
Published: November 2021

Abstract
The regularities of the evaporation flux of pure vapor in the method of lattice Boltzmann equations (LBE) are investigated. The simulations show that the mass flux during the evaporation of a flat surface is proportional to the difference in the densities of the saturated vapor at the surface temperature and surrounding vapor, which is in good agreement with the Hertz–Knudsen law. A simple method is proposed for setting the vapor flow at the flat boundary of the computational domain for the LBE method.
Numerical simulation of the process of gas outflow into an open pipe with an obstacle filled with a liquid (water, lead)
Authors: Vozhakov I S , Lezhnin S I 
Published: November 2021

Abstract
Submerged gas jets find a wide variety of industrial applications, and their behavior is characterized by the ratio of inertia to buoyancy and can vary from the emergence of individual bubbles to stable jets. A numerical study of the high-speed outflow of gas under a pressure of 18 MPa into a cavity with an obstacle filled with a liquid under a pressure of 2 MPa is carried out. The simulation is performed using the VOF method in conjunction with the k-ε turbulence model. The calculations are realized for three distances between the outflow hole and the obstacle: 100, 200, and 300 mm. Principal scenarios of gas jet evolution and characteristic expiration times are obtained.
On the simultaneous growth of multiple hydraulic fractures emanating from an inclined well
Authors: Valov A V 
Published: November 2021

Abstract
The primary focus of this paper is to investigate the interaction between simultaneously propagating multiple fractures, initiated from an inclined well. In particular, the aim is to better understand the influence of the well inclination angle on the stress shadow between the fractures and on the overall resulting geometry of individual cracks. To simplify the analysis, the paper assumes the limit of large perforation friction, which leads to a uniform flux distribution between the fractures. The mathematical model for multiple hydraulic fractures is constructed by coupling together the respective models for individual fractures, each representing a single planar fracture model. In this approach, the fracture induced stress or stress shadow from a previous time step is used as an input for a given single hydraulic fracture to propagate independently. Further, to reduce computational burden, the effects associated with tangential stresses and displacements are neglected, whereby the stress interaction between the fractures is solely described by the normal opening and the normal stress component. Numerical results are presented for the storage viscosity dominated regime, whereby the effects of toughness and leak-off are negligible. An interesting behaviour is observed, demonstrating that the well inclination angle plays a significant role on the overall fracture symmetry. For zero inclination, all the fractures are nearly symmetrical and identical. However, once well inclination is introduced, this breaks the symmetry, making a profound effect on the final result.
Evolution of artificial disturbances in a shear layer at M=1.43
Authors: Vishnyakov O I , Polivanov P A , Sidorenko A A 
Published: November 2021

Abstract
The evolution of artificial disturbances in a laminar boundary layer on a flat plate model in the presence of an incident shock wave is considered. The flow is supersonic with the freestream Mach number M = 1.43. The study is carried out by hot-wire anemometry. A dielectric barrier discharge is used to generate disturbances. Data on the distribution in space of the average and non-stationary components of the mass flow are obtained. Disturbances created by the discharge and their evolution along the separation zone are recorded.
Preparation of human biological fluid for studies by Laser Doppler Spectroscopy
Authors: Chubov A S , Glavny V G , Dvoynishnikov S V , Krotov S V , Meledin V G 
Published: November 2021

Abstract
The paper presents a method for preparing the human biological fluid by the example of urine specimen for studies by Laser Doppler Spectroscopy. The time and storage conditions of the specimen acceptable for correct research are determined. The optimal parameters for measuring and calculating dimensions - temperature, viscosity, refractive index – are identified. The need to filter samples before testing is noted. The centrifugation parameters are determined.
Calibration platform controller of the laser Doppler anemometer
Authors: Glavnyi V G , Rakhmanov V V , Dvoynishnikov S V , Krotov S V , Meledin V G 
Published: November 2021

Abstract
Primary standards for the unit of air flow velocity often use a Laser Doppler Anemometer (LDA) as the primary measurement standard. A rotating disc with a fixed diameter is used to calibrate LDA. The paper proposes calibration platform based on the precision mechanics of HDD disk. A disk rotation controller has been developed for the platform. Deviations of the disk rotation speed do not exceed 0.01% RMS in the range of angular speeds of 600-4800 rpm.
Development of the method of laser Doppler spectroscopy of nanoparticles in liquids and implementation of the method in the LAD-079 spectrometer
Authors: Meledin V G , Dvoinishnikov S V , Kabardin I K , Chubov A S , Bakakin G V , Kabardin A K 
Published: November 2021

Abstract
In this work, a method for physicochemical and biological optical studies of the nanoparticles size distribution is developed. Its implementation in the LAD-079 spectrometer is described. The distinctive features of the LAD-079 spectrometer include the following. Multi-angle parallel measurements of static and dynamic light scattering, scattering angle from 0–180 degrees. Probing at three wavelengths with the ability to analyze the polarization activity of the sample (488 nm, 532 nm, 650 nm). Programmable precision thermostat with an error less than 0.1 °C in the range 0 ÷ +80°C with the possibility of building and software implementation of the experiment plan. Robust monobloc design of the spectrometer that does not require adjustments and a special optical table. The ability to measure the size of dispersed nanoparticles in low-transparent liquids.
Study of the influence of an external flow rate perturbation on the vortex structure and heat transfer in impinging jets
Authors: Tokarev M P , Nichik M Yu , Gobyzov O A , Abdurakipov S S , Dulin V M 
Published: November 2021

Abstract
The study of physical processes dominating in submerged turbulent jets impinging on a wall is an important task because this configuration is utilized in various applications. The efficiency of heat transfer in this configuration has been a subject of a long-term study. Active flow control technique and the optimization of the control signal can be applied to exploit inherent flow properties to further improve the heat transfer from the wall in impingent jets. In this paper, IR-thermography and time-resolved PIV measurements are used for the diagnostics of wall temperature fields and large-scale vortex dynamics under external flow rate forcing control. It is found that the low-frequency forcing (for the Strouhal number St = 0.6) increases integral temperature on the wall as compared to the unforced case and the high-frequency forcing (St = 0.9).
Comparative analysis of working fluids for efficient waste heat recovery
Authors: Lola D Ye , Chirkov A Yu , Borisov Yu A 
Published: November 2021

Abstract
The paper analyzes the implementation of plants with an organic Rankine cycle (ORC) on the example of the circuit of the regenerative gas turbine unit and exhaust gas recovery system of the compressor system of the gas-compressor unit. The theoretically achievable values of power generated by the ORC-installations are determined. A criterion is presented for comparing the working fluids according to the efficiency of use in ORC-installations. To evaluate the overall characteristics of the system, the parameters of heat exchangers for air and water cooling were determined. As a result, it is concluded that the use of ORC-installations allows to utilize up to 23% of the heat of exhaust gases (convert into useful work).
Research of polymers strength properties for 3D printing under normal conditions
Authors: Volkov-Muzylev V V , Vendland L E , Borisov Yu A , Demidov A N , Fominykh N K 
Published: November 2021

AbstractAn article is devoted to the study of the strength properties of interlayer adhesion and determination of Young's modulus by the ball instrumental indentation method for samples, made of various plastics using additive technology under normal conditions. This production method is chosen as the most appropriate for creating lightly stressed parts of complex geometry (up to 30 MPa) in the shortest possible time. One of the possible options for such products is full-size centrifugal wheels layouts of low power gas turbine units (up to 250 kW) for testing them in model conditions. It will ensure the work of the material in the elastic zone. The samples are considered, obtained by FDM method from various polymers such as: acrylonitrile butadiene styrene thermoplastic resin (ABS+), acrylonitrile butadiene styrene thermoplastic resin with addition of carbon fibers (ABS Carbon), nylon with addition of carbon fibers (Nylon Super Carbon), polyethylene terephthalate glycol (PETG) and a compound based on polylactide (PLA HP). Plastics, made by this method, have anisotropic properties. Therefore, in this work, the strength characteristics of the test samples interlayer adhesion under tension are determined.
Generalized model of Kapitza conductance across rough interfaces
Authors: Khvesyuk V I , Liu B , Barinov A A 
Published: November 2021

Abstract
This paper is devoted to the theoretical prediction of the interfacial heat transfer in nanostructured materials. The main task of this work is the analysis of interaction of elastic waves with the rough interface between two different solids. The presence of toughness leads to a significant increase in the resistance to heat transfer in nanostructures. This fundamental problem is discussed in relation to the commonly used method of wave scattering at rough surface: the Kirchhoff tangent plane method. The method assumes that at the point of the rough surface profile, the surface is regarded as locally smooth, and the reflection and transmission of the incident wave can be described by the scattering at the tangent plane of this point. Based on the elastic wave theory, we use the frequency-dependent continuity conditions to calculate the energy transmission coefficient at the interface. And then its effective value at the rough interface is estimated by using the Kirchhoff method. By substituting this effective value into the formula of Kapitza conductance, we can calculate the Kapitza conductance at the rough interface and analyze the effect of roughness on the interfacial heat transfer.
Statistical model of phonon scattering on rough boundaries of nanostructures
Authors: Barinov A A , Khvesyuk V I 
Published: November 2021

Abstract
Because of the rapid development of semiconductor electronics and the tendency to size reduction of the elements of transistors, there is an urgent task of assessing the heat transfer regime, which determines the ability to maintain the required thermal regime. In this work, the heat transfer in micro- and nanostructures in silicon is considered, and a comprehensive analysis of factors determining the heat transfer regime is carried out. In particular, the effect of the interaction of phonons with the sample boundaries in the quasi-ballistic and ballistic heat transfer regimes, where these processes play a decisive role, is evaluated using statistical model of phonon scattering on rough boundaries of samples.
Method for constructing the fundamental equation of state that takes into account the peculiarities of the substance behaviour in a wide vicinity of the critical point
Authors: Rykov S V , Kudryavtseva I V 
Published: November 2021

Abstract
On the basis of the phenomenological theory of the critical point and the Benedek hypothesis, an expression for the Helmholtz free energy F with scale functions in the density-temperature variables has been developed. The proposed free energy equation has been tested on the example of constructing the fundamental equation of state of 2,3,3,3-tetrafluoropropene (R1234yf). By comparison with the known experimental data on the equilibrium properties of R1234yf – density and pressure on the phase equilibrium line, p-ρ-T-data in the single-phase region, the second and third virial coefficients, isochoric heat capacity, isobaric heat capacity and the sound velocity – the operating range of the equation of state of R1234yf has been established according to temperature from 220 K to 420 K and pressure up to 20 MPa.
Modeling of shock-wave loading of carbides as mixtures of components
Authors: Maevskii K K 
Published: November 2021

AbstractThe results of numerical experiments on the modeling of shock wave loading of solid and porous carbides with various stoichiometric compositions are presented. The model is based on the assumption that all the components of the mixture, including gas, have similar pressure, velocity and temperature. The model allows describing the behavior of porous materials and mixes in a wide range of porosity and pressures with precision of experiment. The behavior of complex materials such as carbides is considered as a mixture. The model accurately describes the behavior of the carbides with equal shares of the components of WC, TiC, TaC, NbC and the behavior of boron carbide B4C. Comparison for data of calculation and experimental data was held for carbides with different porosity.
Studying the effect of monochrome light on the photocatalytic activity of tungsten oxide
Authors: Derbasova N M , Gavrish V M , Oleynik A 
Published: November 2021

Abstract
The paper presents studies of the photocatalytic activity of tungsten oxide nanopowder agglomerates under the action of monochrome light in the decomposition reactions of an organic pollutant (methylene blue). It is determined that the radiation of 470 nm (blue) provides the highest values of the rate constant of phototransformation of methylene blue
Developing methods for mathematical modeling of a two-phase dielectric-electrolyte microsystem
Authors: Gorbacheva E V , Kalaidin E N 
Published: November 2021

Abstract
In this paper, we propose a numerical solution to the problem of stability of a two-phase dielectric / electrolyte system under direct and alternating electric fields. The lower wall adjacent to the electrolyte is assumed to be a charged surface, while the upper one is electrically insulated. The charge on the lower surface is supposed to be stationary, and the surface charge on the free interface between liquids is assumed to be mobile. The model is described by a system of Nernst-Planck-Poisson-Stokes equations. The mathematical model is closed by the corresponding boundary conditions. The linear stability of the one-dimensional flow is investigated. At a constant electric field, and the presence of two types of instabilities is found: short-wave and long-wave.
Experimental study of the effect of adding nanoparticles on the rheological properties of oil-based drilling fluids
Authors: Mikhienkova E I , Minakov A V , Matveev A V , Lysakov S V 
Published: November 2021

Abstract
A systematic study of the effect of nanoparticles of various concentrations and sizes on the rheological properties of various oil-based drilling fluids with nanoparticle additives has been carried out. The concentration of nanoparticles in drilling emulsions varied from 0.25 to 2 wt%, and the average size of nanoparticles ranged from 18 to 100 nm. As a result of numerous laboratory experiments, formulations and technology for the preparation of stable oil-based drilling fluids with additives of nanoparticles have been developed. The effect of nanoparticles on the viscosity and rheological properties of these drilling fluids has been studied.
Heat and mass transfer in a metal hydride reactor: combining experiments and mathematical modelling
Authors: Dunikov D O , Borzenko V I , Blinov D V , Kazakov A N , Romanov I A , Leontiev A I 
Published: November 2021

Abstract
Heat transfer in porous metal hydride (MH) beds determines efficiency of MH devices. We present a COMSOL Multiphysics numerical model and experimental investigation of heat and mass transfer in a MH reactor filled with 4.69 kg of AB5 type alloy (Mm0.8La0.2Ni4.1Fe0.8Al0.1). To achieve an agreement between the model and experiments it is necessary to include a flow control device (inlet valve or flow regulator) into the model. We propose a simplified and easy-to-calculate boundary condition based on a porous domain with variable permeability at reactor inlet. The permeability of the domain is connected with hydrogen mass flow by a PID controller. Thus, boundary conditions for the inlet pressure and mass flow are coupled and heat transfer inside the reactor could be calculated without additional assumptions applied to heat and mass transfer in the MH bed.
Heat transfer under conditions of operation of a gas infrared emitter and an air exchange system
Authors: Borisov B V , Kuznetsov G V , Maksimov V I , Nagornova T A , Vyatkin A V 
Published: November 2021

Abstract
In this work, the processes of heat transfer in a premise heated by a gas infrared emitter (GIE) are studied on the basis of numerical solution of the heat and mass transfer equations in a two-dimensional formulation. Calculations are carried out taking into account the presence of supply and exhaust ventilation in the considered area. Ventilation is required during the operation of high-intensity type GIE. The analysis of the main heat and mass transfer parameters by radiant and convective flows is carried out.
The influence of wood processing waste on the technical and energy characteristics of the Maikuben coal-based mixed fuels
Authors: Kuznetsov G V , Cherednik I V , Galaktionova A A , Yankovsky S A 
Published: November 2021

Abstract
The manuscript presents the results of experimental studies of the energy and technical characteristics of mixed fuels based on lignite from the Maikuben basin of the Republic of Kazakhstan and wood processing waste, pine sawdust from the Tomsk LPC. The addition of wood biomass to coal is found to result in a significant reduction in the ash content of the mixed fuel (by 73.1 %) with a wood fraction equal to 50 % and a moderate reduction in calorific value (by 8.2 %) with the same concentration of biomass in the mixed fuel.