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

This work deals with the experimental study of transient flow regimes occurring in the laboratory model of a hydraulic turbine draft tube at a change in the control parameters of setup. The transition from the partial load regime, when a precessing vortex core is formed, to the best efficiency point without a core is considered. To set accurately the speed of runner rotation and the flow rate of the

The problem is considered on a periodical of time motion of a viscous liquid bordering on a solid body and a gas. The liquid is affected by oscillatory influences which have no predominant direction in space. The new hydromechanical effect is revealed which consists in that the free parts of the hydro-mechanical system — liquid layers — perform unidirectional stationary rotational motion with the background

The heat transfer from a single sphere suspended in a cylindrical channel with finely dispersed air-water (aerosol) flow is experimentally studied. Under stationary heating conditions, the values of the heat-transfer coefficients are obtained as dependent on the Reynolds number and the water mist rate. A physical model of heat transfer from the sphere surface with water mist-air flow is proposed, which

A method of direct numerical simulation and a method of solving the boundary-layer equations were applied to parameters of a supersonic boundary layer for a flow past a flat plate (Mach number M = 2) for the case of a plate coated with a sublimation material. The sublimating material is naphthalene (C10 H8). Comparison of results from these two approaches — numerical simulation and solution of a boundary

Stability of the laminar boundary layer on the surface of a hypersonic nozzle for the Mach number M = 6 of the Transit-M wind tunnel is calculated. The laminar boundary-layer profiles are obtained by solving the Navier-Stokes equations numerically within the framework of the Ansys Fluent software. N-factors of the Goertler vortices and of the first and second Mack modes are obtained in the approximation

The effect of mechanically activated coal grinding on the time of their ignition in a vertical tubular reactor is studied experimentally and numerically. The experiments showed that coal, ground by an activator mill (disintegrator mill), ignites faster due to the effect of mechanical activation. According to numerical calculation of the processes of ignition and combustion of mechanically activated

The paper analyzes the complex topology of swirling flows generated in the cylinder by its rotating end face. Using the flow visualization for different parameters of swirl of the upper end of the cylinder, the general laws of the evolution of the region with a counter flow (bubble-like vortex decay) are shown regardless of the contact of the studied vortex flow with various liquids or gas at the free

This work investigates the turbulent flow in a channel roughened by seven ribs of rectangular cross section disposed transversely. The flow configurations of identical ribs from the first one generate a large eddy spreading along the top of the two first ribs, trapping the flow of the first cavity. The widening of the first rib may solve this problem. Therefore, this flow configuration might be required

In the framework of the thermal energy scheme, the growth of a vapor bubble in a uniformly superheated liquid is simulated numerically. The results of numerical calculations are in good agreement with the solution of [3] in a wide range of Jacob numbers. The account for the interfacial surface permeability at high values of Stefan number shows a good match with the results of numerical calculations

The laser-pulse method was used to measure the thermal diffusivity of La98.8Fe1.2 alloy in the temperature range of 293–1623 K of the solid and liquid states, including the regions of phase transformations. The measurement uncertainties of the heat transfer coefficients were ± (3–6) %. Approximating equations and tables of reference data on thermal conductivity and thermal diffusivity of La98.8Fe1

The study is about developing a gasdynamic model of motion of multispeed continua for the case of nozzles with complex geometry. These nozzles imitate the shape of a two-stage confiisor-shaped dust cleaner. The paper studied the influence of force interaction between the gas phase and solid phase in the flow duct of the nozzle; this effect was studied for a wide range of input flow parameters. A special

Results on flight dynamics of an axisymmetric vehicle with a control action in the form of gas jet ejection are reported. The differences in the flight trajectories with and without allowance for the pressure redistribution over the vehicle surface due to transverse gas jet ejection are considered and analyzed. Targeted software is developed on the basis of the equations of motion of a material point

The paper offers a numerical simulation of the heat state for a two-layer semitransparent medium that imitates a hypothetical snow cover upon an opaque semi-infinite substrate; the layers of cover have different absorption and scattering coefficients. Computations were performed for key parameters typical of winter season. It was shown that, depending on the optical thickness of every layer and proportions

This review is devoted to the analysis of the history and current trends in the development of the velocimetry method based on particle images for an aerodynamic experiment. The authors consider the basics of the method, various implementations, former and current status of equipment. Special attention is paid to the methods of data processing and evaluation of various physical values in the flow from

Deformations of a compliant coating in a turbulent flow, measured previously and calculated in this work, are compared. The calculated spectral density of coating deformations at low frequencies (25–250 Hz) turned out to be almost two orders of magnitude higher than the measured one, and the rms value of the measured deformation was seven times lower than the calculated one. The transitional regime

The present work is devoted to the experimental study of a high-speed jet exhausting from a model dual-stream jet nozzle which was performed using non-contact (shadow visualization) and probing (Pitot pressure tube) methods for measuring gas-dynamic parameters. Azimuthal non-uniformity of the pressure distribution, whose magnitude in the external duct is much higher than that in the internal one, is

An experimental fluctuation analysis is usually conducted via thermal anemometry with hot-wires. However, in the vicinity of oscillating shock waves, this kind of sensor can be destroyed due to strong mechanical loads. On the basis of a sufficient modelling, a wedge-shaped hot-film can be suitable for a quantitative fluctuation analysis across a shock wave. Within this study, the modal analysis according

The study of the effect of close placing of two individual elements of roughness with the cylindrical shape on the nature of laminar-turbulent transition were performed. Experiments were performed for a blunt conical model with the radius 9 mm at Mach number M = 5. These double elements of roughness with different heights and divergence angles between elements were allocated at the blunted nose of

The article presents the results of direct numerical simulation of a turbulent vortex ring with a moderate Reynolds number, interacting with the field of external turbulent fluctuations. The ring is formed by buoyancy forces from a spherically-shaped volume of elevated temperature. We consider the interaction of the ring with the field of turbulent fluctuations (of temperature and velocity) located

An unstable laminar flow over a wavy region of a plate placed parallel to the oncoming air flow is studied. The results have been obtained by the hot-wire method in a low-turbulent wind tunnel at low subsonic velocities. Flow near a wall with transverse undulation, whose amplitude is sufficiently large and can contribute to the formation of local regions of boundary layer separation, is considered

The study presents the experimental results for inter-assembly interaction of coolant flows in the core of the VVER consisting of fuel assemblies TVSA-T and TVSA-T.mod.2. The coolant flowing in fuel assemblies (FA) was modeled on an aerodynamic stand. The studies were carried out on the model of the VVER core fragment and consisted in measuring the velocity vector modulus in the characteristic zones

The paper considers nonlinear waves generated on a surface of a horizontal liquid layer put into an assigned stress field at the gas-liquid interface. The nature of branching for wavy modes from the undisturbed flow was studied. To accomplish this, the solution of a model nonlinear equation written for the deviation of the layer thickness from the undisturbed layer is found. Analytical solutions were

The paper deals with the theoretical analysis of viscous liquid films flowing down along a single element of a structured packing with large ribs and microtexture in the form of a wavy two-dimensional surface or three-dimensional surface of the “undulating” type. The effect of inertia forces, surface tension, coarse corrugation, and fine texture geometry on the averaged characteristics of the film

Specific features of the phenomenon of vapor bubble collapse in hot tetradecane (with a temperature of 663 K) are considered for various values of pressures in the liquid in the range from 13 to 100 bar. At the beginning of the collapse, the vapor in the bubble is in the state of saturation with a pressure of 10.3 bar, and with the initial radius of the bubble to equal 500 µm. It is shown that, at

Acoustic streaming in a vibrating air-filled cylindrical cavity is numerically investigated. Adiabatic and isothermal boundary conditions are considered, as well as the case in which adiabatic and isothermal boundary conditions are set respectively at the ends of the cavity and on its lateral surface. The value of the cavity radius at which the axial component of acoustic streaming velocity attains

The developed mathematical model was applied for study of fluid dynamics in a rotational bioreactor for bone tissue engineering by in vitro technology. The research goal is finding an optimal mode for rotation ensuring proper cyclic loading from fluid upon the cell-seeded biomaterial. The basis for developing a mathematical model of a bioreactor was a design of rotational type biological reactor used

A heat storage using the latent heat of the solid-liquid phase change was experimentally investigated. To intensify heat exchange in its design, hyper-heat-conducting plates were used. During the experiments, the temperature values and the volume changes of the working substance (hexadecane) were measured. The analysis of the thermal balance and phase changes in the volume of the heat storage was carried

The paper presents the results of numerical studies of the influence of thermochemical activation of pulverized coal flows on the processes of heat and mass transfer occurring in the areas of real geometry (furnaces) with burning power fuel. The aerodynamic flow pattern, velocity, temperature, and concentration fields were obtained, the analysis of which allows the conclusion that plasma activation

Expressions describing the peculiarities of the temperature field formation in the photoacoustic cell, taking into account the temperature dependence of not only the thermophysical parameters of all layers and the absorptivity, but also of the optical absorption coefficient of the sample have been obtained. A system of nonlinear algebraic equations has been derived to determine the dependence of temperatures

The paper describes the design of an experimental setup for plasma gasification of organic waste with its discrete supply to the loading unit. The experimental results of determining the percentage composition of synthesis gas and its calorific value depending on time for gasification of wood sawdust and polyethylene granules are presented. The amount of methane in synthesis gas composition has been