The paper deals with the experimental study of the process of subcooled liquid boiling up on a transparent microheater with pulsed heat release. Dependences of the maximum bubble diameter, rates of their growth and times of boiling incipience on the heat flux density and liquid subcooling in the ranges of 11–32 MW/m2 and 50–75 K, respectively, were obtained. The nucleation temperature was calculated

The paper presents a study in stability of ceramics of hafnium carbide-nitride subjected to impact of a nitrogen plasma jet in air atmosphere. The best thermal resistance was demonstrated for ceramics with N/C ≈ 0.698, which is determined by the maximum of surface temperature and minimum mass loss in the series of HfC-HfN solid solutions.

The conclusions about the nature of bed fluidization and the rate of polyfractional material entrainment in the cylindrical vortex chamber with the air supply through the lower and upper end swirlers were drawn, based on the visual observation of the fluidized bed, the determination of entrainment of the bed dispersed material by weighing the material after a given time of vortex chamber operation

On the basis of the analysis of a large array of experimental data on average heat transfer and hydraulic resistance, calculations of the dynamic velocity on the wall in deep rows of in-line and staggered tube bundles transversely streamlined by the turbulent flow of the coolant are performed. In addition, energy consumption is calculated based on experimental data on the hydraulic resistance of rod

The work is devoted to the study of a vortex system formed in a flow past a streamwise-aligned external dihedral corner due to the drop of pressure between the corner faces. A detailed comparison of experimental and calculated data on the visualization of the flow and on the distribution of pressure over the model surface obtained at Mach number M∞ = 2.27 in the range of angles of attack α = 0–20°

The effects of the groove size on the dynamical and thermal behavior in a round jet impinging on an axisymmetric corrugated surface are investigated numerically. The geometry is similar to that considered in the experimental study Sagot et al. (2010, Inter J. Therm. Sci., 49, 1026–1030). Three side lengths of the square groove cross section are tested, 1/8, 1/4, and 3/8 of the jet diameter. A comparison

The energy security of Russia is at threat due to recent trends of dependency of national power industry on imported technologies, equipment, spare parts, and materials. The next challenge is a tendency of more strict environmental standards and restrictions for power generation equipment. The paper considers one option to meet these challenges — using technologies based on compressorless combined

In the present study, a numerical investigation was conducted to enhance the film cooling efficiency by using anti-vortex designs. Four configurations are considered in this paper, which are the configuration with the streamwise cylindrical injection, the case with an upstream Barchan dune shape ramp (BDSR), the case with sister holes and the configuration that combine the Barchan dune shape with sister

Mathematical modeling is offered for describing the effect of variable incidence between the body axis and the high enthalpy air flow on conjugated heat and mass transfer in a heat shield material at the thermochemical decomposition of the shield. Results of numerical simulation were obtained for spatial supersonic flow near a body with pitch variations. The effect of body oscillation with the rates

The influence of a local change in surface temperature of a contoured nozzle corresponding to the Mach number M = 6 on the boundary layer stability and laminar-turbulent transition is numerically studied. The profiles of the laminar boundary layer are obtained by solving the Navier-Stokes equations with the use of the Ansys Fluid software system. N-factors of the growth rates of the Goertler vortices

The results of an experimental study of a bubble diameters variation with a distance from the gas injection point in an upward bubbly flow in an inclined flat channel are presented. The measurements were carried out for a superficial liquid velocity of 0.51 m/s (Re = 12400) and various volumetric gas flow rate ratios. It is shown that at low values of volumetric gas flow rate ratio (β < 2 %), there

In this paper, a numerical study is performed to investigate the influence of adding glycol or alcohol to water on the thermal protection of a channel wall from hot air by evaporating this binary liquid film. The coupled governing equations in both phases with the boundary and interfacial conditions are solved using a finite difference numerical scheme. The effectiveness of adding a fraction of glycol

Controlled disturbances are inserted into the wind tunnel flow, and probing measurements of the fields of the amplitudes of pressure and phase velocity oscillations of these disturbances are performed. Based on the relations for inviscid interaction of long-wave vortex, entropy, and acoustic disturbances with the shock wave on a wedge and numerical simulations, the coefficients of conversion of various

The article presents the results of studies of the coolant flow in fuel assemblies behind the intensifier grids of FA-Square reactors of the PWR type. The aim of this work is to evaluate the effectiveness of using various designs of the intensifier grid for the flow mixing. To achieve this goal, a number of experimental studies are carried out on an aerodynamic stand with scale models of fragments

Using the laser flash method and the drop method, the thermal conductivity and the enthalpy increment of the eutectic K-Pb alloy (with a Pb content of 90.7 at.%) were measured in the temperature range from the liquidus point up to 1077–1175 K. The specific heat capacity and thermal diffusivity of the alloy were calculated. Approximation equations for the studied properties were obtained, and a table

The direct shadow photography method was applied for study of the size distribution of droplets produced in liquid fuel atomization by a high-speed jet of superheated steam. This approach for fuel spraying allows eliminating the clogging of fuel lines and atomizers used for combustion of substandard liquid hydrocarbons. The setup has a long-focus microscope lens with optical magnification 7:1; this

The motion of a helical vortex and the movement of the fluid particles along its axis are analyzed. The same form of the helical axis of the vortex and the trajectory of the particles sometimes leads to a false assumption of equality of these two different motions. The correct identification of both motions, however, is essential when considering the helical vortices in the wakes of rotors, or the

Formation of a temperature field and melting rate of ice vertically located on an opaque substrate and scattering radiation at radiant heating were studied numerically. To solve the part of the problem concerning radiative heat transfer, we used a modified method of mean fluxes, which takes into account volumetric absorption and scattering of radiation in the medium, as well as the selective nature

The paper presents an analytical solution for helical vortices with a Gaussian vorticity distribution in the core, which is confirmed by experimental and numerical simulations. This result is obtained by extending the Dyson method to the Biot–Savart law. Previously, analytical solutions were found and studied only for vortices with constant vorticity distribution in the core (a Rankine-type vortex

The paper presents a study for conditions for hydrogen self-ignition and flame spreading in a supersonic combustion chamber at the Mach number for the inlet flow equal to 4. The experimental model is a rectangular channel with a flame stabilizer performed as a backward-facing step. The fuel was injected before the step at the top and bottom walls through 8 round orifices which were oriented at angles

Turbulent flow of thermoviscous liquid is studied in a three-dimensional region with periodicity in two directions. Flow characteristics are described in the terms of equation for turbulent kinetic energy: this allows to differentiate contributions from different components related to generation, transport, and dissipation of turbulent kinetic energy. Those terms can be calculated from averaging the

Numerical studies of the aerodynamic characteristics of the “Federation” reentry vehicle are performed by the direct simulation Monte Carlo method for an altitude of 90 km. Quantitative effects of a number of physical and chemical models of this method on the aerodynamic performance of the vehicle are demonstrated.

Hydrophobic and highly hydrophobic zirconia coatings are obtained by air-plasma spraying of powder and suspension materials. The proposed method and the developed equipment make it possible to obtain nanostructured surfaces with water-repellent properties. The high hydrophobicity of the coating is achieved by creating a hierarchical texture of its surface obtained by the combined method of plasma spraying

The present study is aimed at the development of a laser Doppler anemometer (LDA) for investigating high-velocity multiphase flows. Based on the analysis of the Doppler anemometry methods, requirements to modern LDAs for solving the above-mentioned problems are formulated, and the ways of their implementation with allowance for the present status of laser engineering and spectroscopy are outlined.

Results of a numerical study of the flow structure in the rectangular duct of a model air inlet with the interaction of the shock wave generated by the inlet cowl with the turbulent boundary layer on the inner duct surfaces are reported. A configuration involving a convergent entrance section and a constant-cross-section throat was analyzed. The numerical simulation of the three-dimensional flow with

Unsteady thermal gravitational-capillary convection in a rectangular cavity with sudden heating of one of the vertical walls by electric current was experimentally investigated. The development in time of the spatial form of ethyl alcohol flows with the Prandtl number Pr = 16 at 20°C was studied. The development of the hydrodynamic boundary layer on the heated wall and the flow along the free surface

The paper presents the results of numerical simulation for the process of production of hollow microspheres during heating and melting of porous particles of silica (the precursor) by a flow of low-temperature plasma. This model takes into account the partial capturing of gas in the particle and offers the laws of evolution for the hollow microsphere diameter and the wall thickness for different precursors

The results of numerical simulation of the flow structure and heat transfer in a vertical polydispersed bubbly flow are presented. The mathematical model is based on the Euler approach taking into account the effect of bubbles on the mean characteristics and turbulence of the carrier phase. The polydispersed distribution of bubbles size in a two-phase flow is modeled by the method of delta approximation

The paper presents the results of computer simulation of film cooling behind two rows of trenches on an adiabatic flat plate with coolant supply through inclined round holes in the trench. The calculations were carried out in the wide range of injection parameter from 0.4 to 2.2 using the commercial computer package ANSYS CFX 14 and the SST turbulence model. It was found that for the injection parameter

In the present paper, results of a study of the impact of high-energy effects on the surface morphology and on the formation of the internal structure in PMS-1 copper particles are reported. It is shown that the mechanical milling of the copper powder in a planetary mill leads to the formation of powder agglomerates with a layered structure consisting of numerous deformed ultrafine particles. It is

Using the laser flash method the thermal conductivity of the Rb-Bi liquid alloy with a bismuth content of 27 at. % was measured in the temperature range from the liquidus point to 1173 K. Approximation equations for thermal conductivity and thermal diffusivity have been obtained, and a table of reference data has been developed. An analysis of the measurement results confirms the existing assumption

The results of computational and experimental studies of the flow around a symmetric airfoil with a relative thickness of 12% in the free stream and in a low-velocity wind tunnel with a closed test section are presented. The experiments are performed for the Reynolds number Rec = 0.7·106−2·107 and angles of attack a = −12°÷12°. The problem is numerically solved in a 2D formulation by using the ANSYS

The paper presents results of experimental study for a flow on the windward side of a swept wing with disturbance generators installed on the surface. These generators are 3D roughness elements with the height comparable to the boundary layer thickness. The method of liquid crystal thermography was used for studying the impact of roughness elements with different heights on the boundary layer. There

A mathematical model of solidification of an iron-based binary alloy (Fe-C) modified with nanosize high-refractory particles is proposed. The processes of alloy heterogeneous nucleation on the surface of nanosize particles and those of alloy crystallization in a cylindrical mold are described. For liquidus temperature, a linear approximation of the concentration of dissolved carbon is adopted; the

In this study, laminar magneto-convection flow of a viscous fluid in an inclined enclosure is considered. The temperature gradient is applied on two opposing walls while the other two walls are maintained adiabatic. In order to solve the governing non-linear differential equations, an in-house developed code based on the finite volume method is utilized. The fluid of interest is molten sodium whose

A method for treating experimental data obtained on a setup with free oscillations over the pitching angle of the model and for determining the unsteady aerodynamic characteristics of the pitching moment coefficient is described. It is found that the pitching moment coefficient of a re-entry vehicle model at Mach numbers M = 2 and 2.25 and fixed angles of attack a depends non-linearly on the rate of

Heat transfer, local distributions of Nusselt number, flow structure, and friction characteristics of twisted square ducts are presented. Numerical analysis was carried out to investigate the influence of the twist ratio (TR = p/D = 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0) on the thermal-hydraulic performance of twisted square ducts under constant wall heat flux condition for Reynolds numbers based on

The paper presents the results of experimental study on melting simulator of the fuel coating pin cladding made of alloy Pb (44.5 %)-Bi (55.5 %) and the flow of the melt on the surface of the heated rod. Experiments were conducted for different parameters: heat release, initial temperature, linear size, and the cladding thickness. All experiments provided the video of the process of formation and relocation

In laser cladding, the interaction of laser radiation with the powder flow and the substrate plays a key role. Surface heating depends on the distribution of radiation on the surface of the material, which is determined by the interaction of radiation with the flow of the powder microparticles. Usually, in models for calculating laser beam attenuation, the interaction of radiation with microparticles

A model was developed for solids-liquid flow with any solids concentrations. The model includes the two-phase flow equations for the entire flow. It includes also the rheology law and the particle transfer equation with account for interphase slipping. The statistical model of turbulence accounts for the turbulence modulation by particles. The model was tested on a problem about a steady state flow

Initiation of operation of a ramjet engine with distributed fuel injection along the combustion chamber is studied numerically. A principally important issue is the presence of a compressed air jet producing a throttling effect and preliminary deceleration of the flow to transonic velocities. The Reynolds-averaged Navier-Stokes equations closed by the SST k-ω turbulence model are solved. Hydrogen is

The graph-analytical method (gray model) for estimating the true temperature of an opaque material from both above and below at the unknown character of emissivity dependence on the wavelength is presented. It is shown that if the diagram of spectral distribution of inverse radiance temperatures in the selected spectral range can be approximately represented by a line, convex downwards, then the obtained

The flow structure and thermal efficiency of a gas-droplet wall jet, injected through inclined holes into a transverse trench, is analyzed numerically. The predictions are carried out using three-dimensional RANS equations in the following ranges of two-phase flow parameters: initial droplet size d1 = 0–20 µm and their mass fraction ML1 = = 0–0.05. Gas turbulence is simulated using the model of Reynolds

The work is devoted to the study of temperature dependences of thermal conductivity (T = 300–770 K) of polycrystallic samples of solid solutions based on gadolinium and dysprosium sulfides of the compositions: γ-GdxDy1−xS1.49 (x = 0.1, 0.2, 0.3, 0.4). It has been found that the morphological features of samples, namely, the specific surface area of crystallites, which causes a change in the number

To simulate a cellular flame, rich (equivalent ratio Φ = 1.4) and lean (Φ = 0.9) propane-butane/air mixtures were used in a burner, which forms a stationary flame with a single cell. Experimental data on the temperature fields were obtained using the coherent anti-Stokes Raman scattering (CARS) method; the velocity components were measured using PIV (Particle Image Velocimetry) equipment. The terms

A new method is described for measuring the average void fraction of a one-component two-phase flow moving in a channel with a fixed porous aggregate. The known method of cutting off the flow is used but, in contrast, the vapor phase in the cut-off volume is transferred to the condensed state, and the released space is filled with the measured amount of additional fluid. The result of verification

The enthalpy of the CsBi alloy in the temperature range of 432–1127 K of the solid and liquid states has been measured by the mixing method on a massive isoperibolic calorimeter. Approximation equations have been obtained, and the isobaric heat capacity and enthalpy changes on phase transitions have been determined. The estimated errors of the data on enthalpy and heat capacity of the melt are 0.75

The results of investigating the physical and chemical processes in the wall boundary layer on graphite specimens in a nitrogen flow are reported. The effect of the catalytic wall on the heat flux is considered. The emphasis is on analyzing the distribution of the chemical species concentrations across the boundary layer based on a detailed consideration of the mechanism of heterogeneous catalytic

A method for rapid determination of diffusion coefficients of polar solvents in anisotropic porous materials, making it possible to control the state of products prepared from such materials without destruction, is reported. For implementation of the proposed method, no preliminary calibration of the local solvent concentration in solid phase for the used converter and each new “porous material-solvent”

The paper presents a study of the slip velocity for almost spherical bubbles in a downward laminar tube flow. The local slip velocity is defined as a difference between the mean liquid velocity (measured with electrodiffusional method) and the mean bubble velocity (measured with a modified LDA tool with a small size of measurement volume). The law for slip velocity for downward flow is significantly

The paper presents a theoretical study for a supersonic boundary layer over a flat plate in a stream of air at Mach number M = 2 under the conditions of surface sublimation. The sublimation-prone material is naphthalene (C10H8). Calculations demonstrated that at a higher surface temperature the mass flowrate of naphthalene evaporation is increasing. This reduces the wall temperature in comparison with

The results of a parametric study of hydrodynamic stability in linear formulation of the Blasius boundary layer stability over two-layer compliant coatings are presented. In the calculations, experimental data for real silicon rubbers of several types on the elasticity modulus and the loss factor as functions of deformation frequency are used. Eight pairs of the coatings have been considered. The effect

This paper presents the results of numerical simulation of airflow with suspended particles through a human nasal cavity. The stationary and nonstationary problem statements were considered. Within the nonstationary case, two variants were studied: for the first variant, the breath cycle is taken with symmetric inhale/exhale, and for the second variant, we modelled a real asymmetric breath cycle. The

The flow modes of a vapor-drop mixture in a regasifier-heater of liquefied natural gas are numerically studied on the basis of the model that takes into account polydispersity, power, and thermal interaction of phases, processes of breakup, coalescence, evaporation of droplets, and condensation of steam. The dynamics of the carrier medium is described by the system of Navier-Stokes equations for a

The mathematical model of unsteady heat transfer in the thermionic thermal protection system during high-enthalpy heating is studied numerically. The effect of evaporation of electrons from the emitter surface on reduction of the temperature of the multilayered shell of the thermionic thermal protection system is demonstrated. The influence of some heat transfer agents in the composite shell on the

Here, we consider the empirical relationships presented earlier in the literature that describe the thermophysical properties of H2O + Al2O3 nanofluids, such as viscosity and heat conductivity coefficients. The main parameters affecting these properties of nanofluid are considered to be the volume fraction of particles ϕ, fluid temperature T, and particle size dp. The suitability of approximation formulas

Results of a physical experiment aimed at measuring the profile of relative excess pressure on a control surface in the near zone of the disturbed region of a schematized model of supersonic passenger aircraft (SPA) are reported. Tests in the test section of the T-313 wind tunnel, aimed at identification of the optimum mounting of SPA-model suspension and ensuring measurements of the full profile of

Results of a study of the air-plasma spraying of cavitation- and hydroabrasive-resistant coatings from powder materials are reported. A method of laboratory (bench) testing of coatings for resistance under pulsed impact loads is proposed. The bench is a laboratory impact tester that strikes an indenter brought in permanent contact with the sample. A measure of the damage inflicted to the surface hardened

The paper studies turbulent mixing in thermoviscous fluid flow in a 3D cubic domain which is extended periodically in two directions (X and Y). The flow turbulization develops under the impact of two-dimensional chaotic disturbances at mass average Reynolds number Re1 = 4704. The vortex field structure is discussed in terms of an isosurface of Q-criterion and local enstrophy ζ1. For the advanced stages

The dynamics of evaporation from the confined surface of a horizontal layer of liquid (ethanol) under the action of a gas (air) flow has been experimentally studied. The influence of the longitudinal dimension of the interface (0.01–0.03 m) on the specific mass rate of evaporation was studied. It was found that the specific mass evaporation rate decreases with an increase in the interface length due