bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat transfer in a tube with sudden expansion and additional miniturbulator
Authors: Terekhov V I , Bogatko T V 
Published: December 2020

Abstract
The process of interaction of two separated flows of various scales in a tube with a sudden expansion is investigated. It has been determined that an additional turbulizing element in the form of a small diaphragm leads to dramatic changes in the structure of the recirculation zone in the channel behind a step, shift in the flow attachment point, and, accordingly, redistribution of heat and mass transfer coefficients. The approach of a mini-turbulizer to the separation point increases the size of recirculation zone and heat transfer intensity. An increase in the height of a mini-turbulizer affects similarly the characteristics of a separated flow.
Promising dimple technologies of vortex heat and mass transfer enhancement in energy and microelectronics
Authors: Isaev S A , Popov I A , Mikheev N I , Guvernyuk S V , Nikushchenko D V , Sudakov A G 
Published: December 2020

Abstract
Turbulent separated air flow and heat transfer at the starting hydrodynamic length of the longitudinal section of the dimpled narrow channel (1 in height, 4 in width, and 84 in length) with inclined one-row oval-trench dimples (OTD) are calculated. Packages of 20 and 31 dimples are compared. Each dimple has a length of 4.5, a width of 1, a depth of 0.2, an edge rounding radius of 0.2, and an inclination angle of 45°. Re=6000 and is determined in terms of the flow velocity at the channel entrance. The effect of abnormal separated flow intensification and heat transfer enhancement in OTDs due to the dimple density is confirmed. (fx/fxpl)min=−4 and (Nu/Nupl)max=7.2. Relative heat transfer grows by a factor of 1.9 and relative hydraulic losses – by a factor of 1.6.
The flow of Giesekus fluid around a cylinder between two parallel plates
Authors: Kadyirov A I , Karaeva J V , Zaripov R R , Vachagina E K 
Published: December 2020

Abstract
This paper presents the numerical results of the flow of the viscoelastic Giesekus fluid around a cylinder between two plates. An aqueous solution of polyacrylamide (PAA) is taken as the working fluid. A method for determining the nonlinear parameter of the Giesekus model to approximate the viscosity curve is proposed. The developed method is tested on the approximation of experimental data presented in the literature. The parameters of the four-mode Giesekus model for describing the rheological properties of an aqueous solution of polyacrylamide with concentrations from 2,500 to 10,000 ppm are determined based on a set of experimental data.
Application of machine learning methods for investigating the heat transfer enhancement performance in a circular tube with artificial roughness
Authors: Koroleva A P , Kuzmenkov N V , Frantcuzov M S 
Published: December 2020

Abstract
This paper presents a hybrid approach for investigation of heat transfer enhancement performance using computational fluid dynamics and artificial neural network. More than 5,000 CFD simulations are carried out for turbulent flow in pipes provided with artificial roughness of transverse rectangular ribs to analyze heat transfer, pressure drop, and thermal hydraulic performance. The rib height and pitch are widely varied along with the flow Reynolds number, working fluid, and material of roughness elements. To accurately predict major parameters (Nusselt number, friction factor, and thermal hydraulic performance) a deep neural network is developed, trained, and tested by current CFD data. The ANN allowed finding optimal rib roughness parameters for the current problem and opened perspectives of industrial application due to low computational cost and prediction error of less than 1.5%.
Numerical investigation of heat transfer and friction factor characteristics for staggered double drop-shaped tubes bundle in cross-flow
Authors: Deeb R , Sidenkov D V 
Published: December 2020

Abstract
A numerical study has been conducted to clarify the flow and heat transfer characteristics of a cross-flow heat exchanger with drop-shaped tubes at zero angle of attack. A mathematical and numerical model in software package Ansys for numerical evaluation of heat transfer and flow field of a bundle of drop-shaped tubes, with taking into account the strain caused by different pressures inside and outside the tubes has been developed. The result of the numerical simulation indicates the superior thermal and hydrodynamics performance of the drop-shaped tube bundles over the circular tubes.
Implementation of heat pump systems for minimizing heat losses with ventilating steam supply
Authors: Vendland L.E , Gavrilova Yu.A. , Pugachuk A.S. 
Published: December 2020

Abstract
This article proposes the use of an aircraft compressor for a heat pump installation to potentially increase the thermal efficiency of a combined heat and power (CHP) plant by 5-6%, and save heat in the winter period of a cogeneration turbine. The principle of operation of such a heat pump installation, the scheme of the modernized turbine and the economic justification of the modernization of the steam turbine are presented in this paper. This allowed the confirmation of the feasibility of using a heat pump installation for utilizing the energy of the ventilating steam supply. The quick payback of the project was chosen as a decisive factor in achieving high economic efficiency of the heat pump installation.
Investigation of structured 2D arrays of microdroplets levitating above the surface of hot liquid
Authors: Zaitsev D V , Shatekova A I 
Published: December 2020

Abstract
This work presents new experimental data on the evolution of two-dimensional (2D) ordered arrays of microdroplets levitating over a heated liquid surface. It was found that the average distance between the centers of the droplets in the array increases with the droplet diameter, being practically independent of the number of droplets in the array and substrate temperature. Dimensionless correlation ratios for the distance between the droplets were obtained, which can be used to verify the theoretical models under development.
The effect of the heating rate on the rupture dynamics of the horizontal layer of silicone oil
Authors: Kochkin D Y , Zaitsev D V , Kabov O A 
Published: December 2020

Abstract
The experimental study of the rupture of a horizontal layer of silicone oil non-uniformly heated from below was conducted. The rupture occurred through the formation of a residual film on the heater. Residual film thickness was measured using a confocal sensor. It was found that with increasing heating rate, the thickness of the residual film increases.
The inversion temperature during evaporation of water solutions of ethanol and acetone into a turbulent boundary layer
Authors: Makarov M S , Makarova S N 
Published: December 2020

Abstract
The results of studies of heat and mass transfer during adiabatic evaporation of binary liquids of water/ethanol and water/acetone into a turbulent boundary layer of a vapor-air mixture from a flat wetted plate are presented. The dependences are obtained for the evaporation intensity of solutions of various compositions on the temperature of the air flow or the equilibrium superheated steam into which the liquids evaporate. The inversion temperature values for liquids with different concentration of the volatile component are determined. The effect of flow turbulence on the evaporation rate and inversion temperature is analyzed.
Thermodynamics of single crystals of lithium tungstate with low molybdenum content: heat capacities, enthalpies and lat-tice energies
Authors: Matskevich N I , Stankus S V , Chernov A A , Shlegel V N , Semerikova A N , Samoshkin D A , Zaitsev V P 
Published: December 2020

Abstract
The thermodynamic properties (enthalpy, heat capacity) of lithium tungstate single crystals with low molybdenum content were measured by reaction and differential scanning calorimetry. An equation for lattice energies in Li2WO4-Li2MoO4 system on compositions was established. No anomalies connected with phase transitions for lithium tungstate doped with 15% molybdenum were found up to 960 K. An equation to describe heat capacity was proposed.
The formation of a closed vapor film during boiling of helium II on a cylindrical heater inside the porous structure
Authors: Korolyov P V , Yachevsky I A , Puzina Yu Yu , Kryukov A P 
Published: December 2020

Abstract
The results of experimental studies superfluid helium (He-II) film boiling are presented. Experimental studies of the He-II boiling on the surfaces of the cylindrical heaters in a bulk of He-II and under constrained conditions are described. Visualization of helium-II film boiling was first performed when observed from the end of a cylindrical heater. The scheme of the experimental facility, work cell and heater are given. The data in the form of files with visualization obtained from the experiments allow us to determine the outlines and the characteristic sizes of the films formed during boiling for different initial conditions.
Study on the brewing industry waste combustion
Authors: Larionov K B , Slyusarskiy K V , Tsibulskiy S A , Kaltaev A J , Gubin V E 
Published: December 2020

Abstract
The combustion of the waste from the brewing industry was investigated. Using the elemental analyzer and standard techniques, the elemental composition and technical characteristics of the studied sample were determined. The ignition and combustion of samples were carried out in a combustion chamber at heating medium temperatures (Tg) withinthe range of 500-700 °C. Gas-phase combustion products were analyzed using an in-line gas analyzer. The minimum ignition temperature of the sample was 337 °C. With an increase in the temperature Tg, a significant decrease in the ignition delay time of the sample was observed (by 9.7 times). The combustion process was accompanied by the formation of an intense flame near the sample surface. It was also found that, with increasing temperature of heating medium, the concentration of CO emission decreased with an inverse increase in the extremum value of CO2 emission.
Numerical investigation of the operating process in an annular detonation chamber of low diameter
Authors: Sidorov R S 
Published: December 2020

Abstract
Burning in unsteady rotating detonation waves is one of the ways of operating process organization in future aircrafts engines. However, a minimum combustion chamber diameter in which the unsteady rotating detonation process can be actualized is a significant limitation of such engines. A possibility of hydrogen-air mixture burning in an annular chamber with a diameter of 78 mm is shown in this paper using methods of three-dimensional computational fluid dynamics. The geometry of the chamber and the modes of its operation were selected, and the influence of the total pressure of air at the inlet was studied. At the pressure of 32 bar, the mass flux in the critical section of the aerodynamic nozzle was 7349.2 kg/(s·m2). It is shown that in a rotating reference frame in which the detonation wave is at rest, streamlines come to the wavefront almost at right angles. This fact allows making simple estimates of the fresh mixture parameters in front of the wave. Comparison with the detonation parameters in a premixed hydrogen-air mixture in the tube showed that the velocity of the detonation wave in the chamber is 0.65-0.74 of the Chapman-Jouguet detonation velocity, and its height is approximately equal to the characteristic size of the cellular structure of the detonation.
The structure of the Black Sea mesoscale eddies from the numerical modeling with various spatial resolution
Authors: Puzina O S , Mizyuk A I 
Published: December 2020

Abstract
The paper is based on the numerical modeling results and investigates the dynamics of the Batumi vertical structure of anti-cyclonic eddy. In the autumn-winter period, the Batumi Eddy intensifies; in the spring-summer period, the eddy weakens. In the calculation with a higher resolution, the eddy dynamics is more pronounced in comparison with the calculation with a low spatial resolution. The vertical structure of the Batumi Eddy was determined for temperature fields, current velocity and salinity.
Phase triangulation method for measuring 3D geometry of complex profile objects under dynamic noise
Authors: Dvoynishnikov S V , Rakhmanov V V , Meledin V G , Sadbakov O Yu 
Published: December 2020

Abstract
The paper proposes a method of phase triangulation for measuring the three-dimensional geometry of complex objects under conditions of dynamic noise. The method is based on statistical analysis of experimental data, adaptive filtering and use of a controlled source of structured exposure. Theoretical and experimental estimates of the error by the proposed method are presented in the paper. The method allows a reduction in the measurement error of the three-dimensional surface geometry of complex objects using phase triangulation methods.
Approbation of the Laser Doppler Anemometer under Kinematic Flow Parameters Diagnostics during Spray Formation in a Laboratory Wind-Wave Interaction Modelling
Authors: Kabardin I K , Meledin V G , Dvoinishnikov S V , Troitskaya Yu I , Kandaurov A A , Sergeev D A 
Published: December 2020

Abstract
The sea spray, a typical feature of the marine atmospheric boundary layer, is one of the most uncertain factors among those controlling hurricanes and severe storms. To investigate how extremely strong winds tear off spray from wave crests, to classify such events, and to quantify the efficiency of the disclosed mechanisms, the high-speed wind-wave flume was constructed. For development of understanding of spray formation under hurricane wind condition the information about velocity distribution is required. The flow kinematics inside the wind-wave was studied using a laser Doppler anemometer (LDA) with an adaptive temporal selection of the velocity vector (LAD-08).
Heat capacity of liquid Cs80Bi20 alloy with a partly ionic character of interatomic interaction
Authors: Khairulin A R , Savchenko I V , Stankus S V 
Published: December 2020

Abstract
Enthalpy increment of CS80Bi20 liquid alloy in the temperature range of 857–1076 K was measured by mixing method on a massive calorimeter with an isothermal shell. The heat capacity of the melt was determined and it was found that for the studied temperature range it remains constant, and its absolute value exceeds significantly the calculation by the additivity rule. The estimated errors for enthalpy and heat capacity of the melt were 0.4 and 1%, respectively. An approximation equation was obtained for the dependence of the mass heat capacity of the solid alloys of the cesium-bismuth system at 298.15 K by the atomic concentration of bismuth.
Intensification of electrohydrodynamic flows using carbon nano-tubes
Authors: Korobeynikov S M , Ridel A V , Karpov D I , Prokopenko Ya G , Bychkov A L 
Published: December 2020

Abstract
Study of behaviour of floating up bubbles in the mixture of transformer oil with carbon nanotubes under the action of high electric field was carried out. The possibility of using carbon nanotubes to create hydrodynamic flows in a liquid dielectric at a very low concentration of nanotubes is shown. It is assumed that the mechanism of the formation of flows is the injection of charge from the surface of nanotubes.
Influence of wood biomass on physical and chemical transformations during its joint high-temperature pyrolysis with coals
Authors: Kuznetsov G V , Tolokolnikov A A , Cherednik I V , Yankovsky S A 
Published: December 2020

Abstract
The article deals with a comparative analysis of the influence of wood biomass on the pyrolysis processes of three grades of coal, namely, “lean” (T), “long-flame” (D), and “lignite” (3B). The composition of the ash residue of the main components of fuels and mixtures based on them was determined experimentally using X-Supreme 8000 element analysis device. Fuel mixture samples were used with a percentage of wood/coal equal to 0/100, 10/90, 25/75, 50/50 wt.%. The experiments were performed in an inert gas (argon) environment within the temperature range from 400 to 800 °C. It was established that during pyrolysis of two-component fuels based on three different coals (T, D, and 3B) in a mixture with dispersed wood biomass (sawmill waste), the effect of the growth of calcium and aluminum sulfates was achieved in the ash of the thermal decomposition products of such mixtures due to a complex of reactions between pyrolysis products of coals and wood where the concentration of the wood component in the mixture changed from 10 to 50%. The results of experimental studies allow substantiating the previously formulated hypothesis about the sequestering mechanism of sulfur oxides formed during the pyrolysis of coals, as a result of the interaction of water vapor with gaseous products of thermal decomposition of wood and solid products of pyrolysis of three coals of different grades.
Numerical analysis of the effects of intense energy flows on a cylindrical target in a magnetic field
Authors: Kuzenov V V , Dobrynina A O , Shumaev V V , Starostin A V 
Published: December 2020

Abstract
In this paper, a new version of the method for numerically solving the equations of radiation magneto-plasma dynamics is presented. The developed numerical technique was verified by solving a number of test (model) problems. The one-dimensional calculations of the plasma-dynamic parameters of a cylindrical target for the combined scheme of the effects of magnetic inertial fusion take into account a wide range of physical effects. A method is proposed for the transition from a tetrahedral to a hexagonal irregular computational grid. A variant of the elliptic “regularizer” of the grid is developed, which is based on the “mechanical analogy” and is based on the solution of linear equations of the theory of elasticity. The paper presents the initial results of the reconstruction and “regularization” of the computational grid, as well as the distribution of the “angular” criterion for assessing its quality.
Cost optimization for information security systems
Authors: Kryanev A V , Kudryashov N A , Sliva D E 
Published: December 2020

Abstract
Protecting information that is potentially accessible through external communication channels from external threats is one of the primary objectives of information security. Creating an information security system requires material investments, the cost of which increases along with the increasing degree of information protection. Therefore, the task of determining the level of investment in information security that provides the minimum total cost of the information protection system and losses from realized threats that remain after the implementation of the information protection system arises. In this paper, we present a scheme that allows us to solve the problem of optimizing the costs of an information security system, the implementation of which ensures a minimum of average total costs for the implementation of the information security system and losses due to the remaining threats realized after the establishment of information security system.
Strain localization in two-dimensional lattices
Authors: Porubov A.V. , Antonov I.D. , Sokolov A.A. , Müller W.H. 
Published: December 2020

Abstract
Two-dimensional localized strain wave solutions of the nonlinear equation for shear waves in two-dimensional lattices are studied. The corresponding equation does not possess an invariance in one of the spatial direction while its exact plane traveling wave solution does not reflect that. However, the numerical simulation of a two-dimensional localized wave reveals a non-symmetric evolution.
Numerical solution of two-dimensional (2D) nonlinear heat conductivity problem on moving grids
Authors: Shilnikov Kirill E. , Kochanov Mark B. 
Published: December 2020

AbstractFor the numerical solution of two-dimensional (2D) nonlinear heat conduction problem a transition to a moving coordinate system is used. A local speed of the latter is chosen in such a way that the considered process is close to stationary. Such coordinate system guarantees a concentration of grid nodes in a range of the solution features. This allows for a quality improvement of the obtained numerical solution with a small number of computational grid nodes. The developed numerical algorithm is tested on the heat wave propagation problem which has an exact solution.
Preparation of Mo-S-P electrocatalytic films by pulsed laser ablation of MoS2/P composite target for effective hydrogen production
Authors: Rubinkovskaya O V , Fominski D V , Romanov R I , Nevolin V N , Yu Fominski V 
Published: December 2020

Abstract
The results of structural and electrochemical studies of thin Mo-S-P films obtained by pulsed laser deposition at various conditions from a target made of mixture of MoS2 and P powders are presented. For variation of S/P ratio and modification structure of the catalytic films, the deposition of the laser plume was conducted in vacuum, in Ar and H2S gas. The highest electrocatalytic properties for activating the hydrogen evolution reaction in an acid solution were found for composite amorphous/nanocrystalline MoS6P/nc-Mo films. In the chemical stateof S 2p, the high binding energy dominated. The doping of the films with phosphorus increased the efficiency of the reaction compared with that of MoS
x
/nc-Mo films. The analysis of the synergistic effect of phosphorus on the performance of amorphous MoS
x
P
y
films in H2 evolution was carried out using the density functional theory.
Modeling of heat and hydrodynamic processes in the big uranium target “BURAN” under the action of high-energy ions
Authors: Efremov V. , Kiverin A. , Yakovenko I. , Baldina E. , Baldin A. , Bleko V. 
Published: December 2020

Abstract
This paper is devoted to the analysis of heat transfer, hydrodynamic and acoustic processes induced by high-energy particles irradiating the big uranium target “BURAN”. The generation of heat and acoustic waves by relativistic ion beams is studied numerically. Energy transfer between irradiated target and ambient atmosphere was analyzed with different models. The study provides a basis for development of the new acoustic method for analysis of ion beam energy deposition and its further redistribution in the bulk of a target.
The thermographic study of the surface discharge electrode systems with a fixed and moving dielectric barriers
Authors: Ivchenko A V 
Published: December 2020

Abstract
The paper presents the thermographic investigation results of temperature fields on electrode systems of surface discharges excited on a fixed and moving dielectric layers. It is shown that temperature in the electrode systems with stationary dielectric barrier is of 28-1350C while temperature of electrode systems with a movable dielectric layer doesn’t exceed 500C. The effect of near-wall gas flows on the surface temperature distribution of electrode systems is discussed.
Cumulative effect in foams and mechanism of detonation development
Authors: Kiverin A D , Yakovenko I S , Kichatov B V , Korshunov A M 
Published: December 2020

Abstract
The paper is devoted to the analysis of non-steady combustion and detonation in aqueous solutions foamed with the hydrogen-oxygen gaseous mixture. The processes of flame acceleration and transition to detonation are studied experimentally and numerically. Based on complex analysis, the effect of cumulative compression of the reactive gaseous mixture inside collapsing bubbles is proposed to be the mechanism of detonation formation and its further self- sustained propagation. Flame propagation through the foam leads to the compression waves generation. Under the action of compression waves, the gas bubble collapses, and states with high energy densities are achieved inside the bubble. As a result, the ignition inside the bubble takes place that represents a basic mechanism of detonation formation and propagation.