bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of eigenmodes in a swirling jet and flame: 3D PIV and PLIF study
Authors: Abdurakipov S , Lobasov A , Chikishev L , Dulin V 
Published: December 2019

Abstract
The existence of spiral structures was directly confirmed experimentally on the basis of 3D Particle Image Velocimetry (PIV) and planar laser-induced fluorescence (PLIF) measurements both in a strongly swirling non-reacting jet and in a fuel-lean premixed methane-air flame. Flows were characterized by the presence of vortex breakdown and precession of the vortex core. The differences in magnitude and spatial distribution of flow eigenmodes with distance from the nozzle are analyzed by using Proper Orthogonal Decomposition (POD) based on Spatial Fourier Transform over azimuthal coordinate. The analysis of flow eigenmodes reveal that for a high-swirl isothermal jet, the vortex core co-existed with the pair of counter-rotating helical vortices, which were located in outer shear layer and inside the recirculation zone. This double-vortex helical structure was also detected in a swirling flame, but its magnitude was suppressed compared with isothermal flow. It was determined that the change in the shape of the chemical reaction area was associated with two types of large-scale coherent structures: nearly axisymmetric mode m = 0 of the flame front deformation, presumably due to the effect of buoyancy forces on the combustion products, and the quasi-solid rotation of the asymmetric global mode |m| = 1 in the form of double-vortex structure due to precession of the swirling flow. It was shown that the energy of the axisymmetric mode m = 0 in a reacting jet increased downstream by almost 10 %, unlike other modes, whose energy was only diminished.
Numerical simulation of liquid hydrocarbon fuel burning in a direct-flow evaporation burner in a jet of superheated steam
Authors: Dekterev Ar A , Minakov A V , Anufriev I S 
Published: December 2019

Abstract
In this work, the process of diesel fuel combustion in a laboratory sample of an original evaporation-type burner with superheated steam supply to the reaction zone was investigated by numerical simulation. Fuel burning in such a burner occurs in a steam jet flowing through the nozzle. In the framework of research, a mathematical model was developed, the influence of various models of turbulence, approaches to simulation of combustion, and response schemes were investigated.
Numerical simulation of transient mixing and ignition processes in a supersonic combustor chamber
Authors: Zakharova Yu V , Fedorova N N , Goldfeld M A , Vankova O S 
Published: December 2019

Abstract
The paper presents the results of a numerical and experimental study of the processes of mixing and combustion in a model combustion chamber under conditions of multi-jet injection of hydrogen into supersonic (M = 4) external flow. Numerical simulation is performed for the conditions of experiments conducted in a high-enthalpy short-duration facility IT-302M. Joint analysis of experimental and calculated data allows us to obtain new data on the structure of the flow and describe the process of ignition and flame propagation through the channel of the combustion chamber under the conditions of unsteady (falling) input conditions.
Combustion of round hydrogen microjet in a cocurrent air flow
Authors: Kozlov V V , Grek G R , Katasonov M M , Litvinenko M V , Litvinenko Yu A , Tambovtsev A S , Shmakov A G 
Published: December 2019

Abstract
Experimental data on combustion of a round hydrogen microjet in a cocurrent coaxial air jet are presented. As is found, the combustion of microjet is dominated by the generation of “bottleneck-flame region” that is in agreement with our previous observations on the diffusion combustion of subsonic hydrogen microjets. Transformation of the spherical “bottleneck-flame region” to a cylindrical one is observed. At supersonic combustion of the round hydrogen microjet, supersonic cells are generated both in the microjet and in the cocurrent coaxial air flow. A feature of the combustion process is the flame lift-off from the nozzle exit.
Numerical simulation of premixed methane/air and synthesis gas/air flames for turbulence swirling jet
Authors: Lobasov A S , Dekterev Ar A , Minakov A V 
Published: December 2019

Abstract
This paper reports on the investigation of combustion features of turbulent swirling methane/air and synthesis gas/air flames via using modern CFD-approaches. For methane/air mixture the equivalence ratio Φ was 0.7 which is near to the lean blow off limit. Two regimes with 1:1 and 1:2 ratios of hydrogen and carbon monoxide in the fuel mixture have been considered for synthesis gas combustion. For validation of numerical models, the reliable experimental data has been used. It is found that LES approach demonstrates good agreement with the experimental data. Comparison between methane/air and synthesis gas/air flames demonstrates that in the latter case the size of recirculation zone and the flame temperature are decreasing. But, addition of carbon monoxide in synthesis gas/air mixture leads to flame temperature rise.
Gradient ceramic structures formation from an impact jet of vapors of organometallic compounds flowing onto the hot barrier
Authors: Lukashov V , Abdrakhmanov R , Vasilieva I , Igumenov I 
Published: December 2019

Abstract
Chemical vapor deposition of coatings (MO CVD) using volatile organometallic compounds is considered. The results of the analysis of coating parameters by X-ray diffraction methods, microscopic visualization and differential dissolution confirm the possibility of controlling the composition and structure of the coatings by varying the parameters of the deposition process. The obtained data laid the foundations for the physicochemical process of forming thermal coatings with given functional characteristics.
Regimes of filtrational gas combustion in a cylindrical annular burner with radiation heat transfer
Authors: Palesskiy F S , Minaev S S 
Published: December 2019

Abstract
A problem of premixed filtrational gas combustion in a cylindrical annular burner has been solved in the frame of one-dimensional diffusion-thermal model taking into account internal radiative heat transfer in porous burner and radiative heat flux emitted by internal layers of porous material. Two different stationary combustion regimes are detected under the same values of gas flow rate. It was shown that stationary flame radius depends on the initial ignition conditions. Solid and gas temperature characteristics depending on flame radius and gas flow rate are studied. Estimation of the burner radiation efficiency is carried out. Significant difference between temperature characteristics of gas and solid phases and burner radiation efficiency for different combustion regimes are shown.
On combustion regimes of syngas-air and methane-air lean flames for swirl-stabilized burners
Authors: Tolstoguzov R V , Sharaborin D K 
Published: December 2019

Abstract
This work presents result of visualisation of the characteristic combustion regimes of methane-air and syngas-air swirl-stabilized flames for an unconfined premixed burner (Re = 5000) and non-premixed combustion chamber (Re = 30000). Equivalence ratios were selected to have nearly equal values of the laminar flame propagation speed for the methane/air and syngas/air flames. Visualization for the premixed combustion for the model swirl burner revealed a similar shape of the flames for all mixtures. In contrast, during combustion of methane and syngas in the combustion chamber in the case of combustion in the combustion chamber, these differences in parameters cause completely visually diverse combustion modes.
Three-dimensional simulation of gas injection into an open fluid-filled pipe region
Authors: Alekseev M V , Vozhakov I S , Lezhnin S I , Pribaturin N A 
Published: December 2019

Abstract
Three-dimensional simulation of air injection into a liquid (water, liquid lead) at large pressure drops in a three-dimensional formulation has been carried out. A significant difference in the formation of the air volume form at injection of water and liquid lead is shown. The instability of the interfacial surface in the form of annular waves and axial cavity on the upper surface of the slug has been revealed in three-dimensional calculation. For the three-dimensional case the gas-dynamic structure of the compression jumps and the Mach disk is found to be more pronounced for the supersonic underexpanded jet inside the slug.
Influence of flow conditions on compression surfaces of hypersonic inlet on characteristics of boundary layer bleed
Authors: Goldfeld M A 
Published: December 2019

Abstract
The paper presents the results of analytical and experimental study of the bleed coefficient at flight Mach numbers from 3 to 7. For the calculation, a calculation model with a fixed exit in the supercritical bleed mode was used, which allows varying the bleed air mass depending on flow conditions and parameter of the bleed system. The measurement of the bleed flow coefficients were performed for three bleed configurations in a wind tunnel at local Mach numbers in front of the bleed area from 2.5 to 5.96. The model had a long forebody, so that before the bleed area there was a thick boundary layer. As a result, new experimental data on bleed coefficient and its general dependence on the Mach number of up to 6 and the bleed angles of 90° and 45° were obtained. It is revealed that at an increase in the local Mach number, the tendency towards a decrease in the bleed coefficient is observed, and this tendency becomes more intensive with a decrease in the bleed channel inclination. These data were used to evaluate known analytical calculation method to determine the characteristics of bleed systems at hypersonic flow velocity.
Effect of conjugate heat transfer on the side and horizontal walls on the structure of convective flow in the Rayleigh-Benard convection mode
Authors: Danilov N I , Mitin K A , Berdnikov V S 
Published: December 2019

Abstract
Rayleigh-Benard convection in rectangular cavities with different relative size with walls of finite thermal conductivity is studied numerically in a two-dimensional conjugate formulation. The influence of relative cavity sizes on the spatial shape and evolution of convective flows with increasing Rayleigh numbers is investigated. Velocity and temperature fields in the liquid, temperature fields, temperature gradients and heat fluxes in solid walls are calculated. The effect of conjugate heat transfer with walls of finite thermal conductivity on the spatial shape and local characteristics of convective heat transfer is studied.
Temperature distribution in a cylindrical container with crude oil after ultrasonic treatment
Authors: Kadyirov A I , Karaeva J V , Makarushkin D V 
Published: December 2019

Abstract
The distribution of oil temperature in a cylindrical container is researched experimentally after ultrasonic treatment with frequency 22 kHz. Samples of crude oil were considered as a working fluid with effective viscosity 3-4 Pa*s and 0.029-0.03 Pa*s. The capacity of the ultrasonic device varied from 80 to 160 W. Temperature gradient is obtained over the height of the container for more viscous oil.
Hydraulic and gas-dynamic models of a steam-water mixture flow in a granular bed
Authors: Tairov E A , Khan P V 
Published: December 2019

Abstract
The paper presents a comparative analysis of the hydraulic and gas-dynamic models of a steam-water mixture flow through a granular bed. The analysis is carried out using experimental data obtained at an inlet pressure of 0.6 - 15.5 MPa, flow quality of 0.002 - 0.3, and mass velocity through a cross-section of a packed bed from 44.5 to 410 kg/(m2s). In the hydraulic model, with a view to improving the accuracy, the algebraic calculation of an average pressure is replaced with numerical integration over the bed height. In the gas-dynamic model, which allows analytical integration, refined constitutive relations are proposed. An analysis of the obtained results indicates that the gas-dynamic model provides a good description of experimental data, whereas the hydraulic model leads to a considerable error in calculation in the case of large relative pressure drops.
Model of reduced kinetics for describing heterogeneous detonation in gas particle mixtures with non-uniform concentration distribution
Authors: Khmel T A , Tolkacheva S I 
Published: December 2019

Abstract
A simple model of reduced kinetics is proposed to describe the detonation combustion of gas particle suspensions with a non-uniform concentration distribution. The model is verified on the basis of empirical data on the dependence of the detonation velocity on the particle loading. The model constants for the substoichiometric and superstoichiometric suspensions of aluminum particles in oxygen are determined. The formation of suboxides and incomplete combustion of aluminum are taken into account integrally. Examples of numerical simulation of the Chapman-Jouguet detonation propagation in mixtures with longitudinal concentration gradients and cellular detonation in lean and superstoichiometric mixtures of aluminum and oxygen are presented.
A small-mode model for spatial regimes on a freely falling liquid film
Authors: Tsvelodub O Yu 
Published: December 2019

Abstract
Spatial wave modes of a viscous liquid film freely flowing down a vertical wall are considered. In the case of small Reynolds numbers the problem is reduced to considering solutions of a nonlinear equation for the film thickness deviation from the undisturbed level. It was used to obtain a model system of equations, describing spatially periodic solutions with wave numbers lying in the vicinity of special resonance points and symmetric in the transverse coordinate. Several solutions for this system are provided.
Contact angle dynamics for evaporating droplet on contrast nano-structured surface
Authors: Bochkareva E M , Lei M K , Miskiv N B , Starinsky S V , Terekhov V V 
Published: December 2019

Abstract
In this work, a series of experiments was carried out to study the evaporation rate of sessile and suspended droplets. The basic geometric characteristics of an evaporating drop from a biphilic surface are investigated. Evaporation dynamics data have been obtained, showing that evaporation from an inverted substrate is faster than evaporation of a sessile drop.
Features of heat transfer during the evaporation of a drop of nanofluid
Authors: Bochkareva E M , Miskiv N B , Nazarov A D 
Published: December 2019

Abstract
In the present work, experimental studies of factors affecting heat and mass transfer during the evaporation of droplets of nanofluids with SiO2 nanoparticles (base liquid - water) were carried out in a wide range of mass concentrations and initial environmental parameters (temperature and flow rate). According to the results of the study, it was found that the effect of nanoparticles under forced convection depends on the initial environmental conditions.
Vacuum freezing of clay porous material
Authors: Fedoseev A V , Salnikov M V , Demin N A , Sukhinin G I , Yarygin I V , Prikhodko V G , Novopashin S A 
Published: December 2019

Abstract
The results of experimental measurements of a temperature distribution in a clay layer of finite thickness for a vacuum drying process are demonstrated. The results of the experiment were compared with the results of the numerical model. An incomplete correspondence between two approaches was obtained. The effect of width of the clay layer on the course of the vacuum drying process is shown.
The effect of evaporation on a horizontal liquid film rupture
Authors: Kochkin D Y 
Published: December 2019

Abstract
This work is devoted to the experimental study of the rupture of a horizontal liquid layer placed on a stainless steel substrate non-uniformly heated from bellow. The goal of this work is to study the dynamics of film deformation and to determine the effect of evaporation and film thickness on the rupture. The film thickness and the deformation profiles were measured using the confocal Micro-Epsilon system with a positioning system. Liquid film initial thickness varied from 300 to 850 μm.
The experimental investigation of the evaporation rate of nanofluids based on different fluids
Authors: Lobasov A S , Minakov A V 
Published: December 2019

Abstract
The evaporation of the nanofluids based on Al2O3 nanoparticles and different fluids was experimentally investigated. The distilled water and isopropyl alcohol were used as base fluids. The average diameter of Al2O3 particles was 100 nm. The investigations of fluids evaporation rates were carried out using the Simultaneous Thermal Analyzer STA 449 C Jupiter (NETZSCH). The investigation of the evaporation rate dependence on the carrier media was carried out. It was found that the average relative evaporation rate of fluids increased, and the time of complete evaporation accordingly decreased with an increase in the volume concentration of nanoparticles. In addition, the absolute value of the evaporation rate was found to significantly depend on the type of base fluid. However, the relative value of the evaporation rate for different base fluids remains approximately the same.
Experimental studies of non-stationary thermo-hydraulic processes at freon R113 boiling
Authors: Milman O O , Ananyev P A , Korlyakova M O , Miloserdov V O 
Published: December 2019

Abstract
An experimental unit has been created to study the processes of boiling and condensation in a closed loop. Experimental studies of non-stationary thermo-hydraulic processes at freon R 113 boiling have been carried out inside tubes of low pressure natural circulation systems. Key factors have been identified affecting auto-oscillations characteristics: filling level of the loop, pressure, heat flux density, geometric characteristics of the evaporating elements. Four characteristic modes of operation of such units have been found out. Thermo-hydraulic auto-oscillations at high thermal loads have been studied. Process parameters and conditions under which there is no thermo-hydraulic instability have been determined. The phenomenon of thermo-hydraulic resonance has been detected. The influence of the heating method on the instability characteristics has been revealed.
Experimental study of condensation of dielectric liquid in microchannel heat exchanger
Authors: Shamirzaev A S , Kuznetsov V V 
Published: December 2019

Abstract
This study presents the results of an experimental investigation of the heat transfer under condensation of perfluorohexane inside the horizontal multi-microchannel system. The copper heat exchanger contains 21 rectangular microchannels with 335x930 μm cross-section. The heat from the condensing flow is rejected to a flow of water by Peltier modules. Experiments are performed in a range of mass fluxes from 90 to 200 kg/m2s and vapor qualities from 1 to 0. Obtained data set on heat transfer is compared with theoretical predictions.
Gradient heat flux measurement in study of unsteady water film boiling at the surface of the sphere
Authors: Sapozhnikov S Z , Mityakov V Yu , Subbotina V V 
Published: December 2019

Abstract
The new method of study heat transfer is the gradient heat flux measurement. It allows measuring the heat flux per unit area for unsteady film boiling at the spherical surface. For the first time distribution over the surface of heat flux per unit area and heat transfer coefficient were derived. The time dependences for the local heat flux per unit area and heat transfer coefficient were obtained in different angles of the spherical surface. The spherical surface was made of titanium VT 22 with a diameter of 20 mm. High-speed shooting supplemented the experimental curves with a frequency of 1 kHz. The error of heat flux per unit area measurement was not exceeding 12%.
The influence of Prandtl numbers of melts and crucible materials on the features of crystal growth by the Bridgman method
Authors: Berdnikov V S , Kislitsyn S A , Mitin K A 
Published: December 2019

Abstract
The processes of crystallization of silicon and heptadecan in flat-bottomed cylindrical crucibles in conjugate convective heat transfer regime were studied numerically by the finite element method. Crystallization of silicon was investigated in a graphite crucible. Crystallization of heptadecane was investigated in a Plexiglas crucible. The possibility of existence of two convective vortices over a solidification front during the crystallization of silicon and heptadecane has been discovered. Crystallization of heptadecane was studied at two rates of lowering the crucible into the cold zone. Lowering of the crucible was simulated by moving the breakpoint in the temperature distribution on the outer side of the crucible walls. The breakpoint was the boundary of transition from the wall area heated to the initial temperature to the area with a given temperature gradient. Adaptive grids on triangles tracking the position of the crystallization front at each time step were used. The software package of developed by the authors was used.
On the possibility to improve heat transfer of a sphere by natural convection and water mist
Authors: Abed A H , Klimova V. A. , Shcheklein S E , Pakhaluev V M 
Published: December 2019

Abstract
This paper aims to evaluate the effects of water mist on steady natural convection heat transfer from a sphere. Experimental investigations were performed for the Nusselt number (Nu) under a range of water mist concentration in both cases, sphere located in an open volume space with constant surrounding temperature and inside a cylindrical channel with sphere-to-channel diameter ratio (d/D=0.73). The results obtained from the related experimental work indicated that the heat transfer rate was enhanced over that for the single-phase air flow as a result of water mist evaporation on the heated surfaces. Compared to air cooling over a range of heat flux investigated, the percentage enhancement in the overall thermal factor was about 40%, 95.4%, 129.4%, and 156.8% respectively for all water mist concentration. In addition, an empirical correlation was also formulated to estimate the real benefits of using the water mist of the enhanced sphere.
Heat transfer in PCM based closed radiator heated from a source of variable power
Authors: Bondareva N S , Sheremet M A 
Published: December 2019

Abstract
In the present study, the numerical problem of heat and mass transfer in a closed copper radiator filled with n-octadecane heated from an energy source with an unsteady volumetric heat generation was considered. Governing equations in dimensionless nonprimitive variables “stream function – vorticity – temperature” describing conductive and convective heat and mass transfer processes taking into account the melting phenomenon were given. The evolution of temperature fields and the integral heat exchange coefficient at different heat release regimes was considered.
Experimental study of two-stage combustion of anthracite mining waste
Authors: Butakov E , Burdukov A 
Published: December 2019

Abstract
Here we consider the task of studying the flame burning of low-grade coals and their significantly ballasted waste with a low volatile yield and reactivity. It is shown that when reducing the quality of coal fuel, it is advisable to use two-step combustion methods with preliminary mechanochemical activation, which allows start-up of the boiler from a cold state without application of auxiliary fuels. The methods of mechanochemical activation have proven to be effective technologies for start-up of the boiler and maintaining the combustion of coals of different quality and technical composition. The developed technologies allow approaching the full-scale experimental-industrial implementation at thermal power plants. The two-stage system allows significant reduction in the cost of preparing micro-ground coal and number of start-up of the burners, since fuel from a standard boiler mill is supplied to the second stage with a different ratios, depending on the reaction properties of the fuel, i.e. it is possible to increase the power of a of start-up of the burner several times as compared with single-stage combustion.