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

The impact of weak shock waves on the boundary-layer flow of a flat blunt plate installed along the stream was experimentally studied for different sweep angles of the leading edge of the plate at Mach number 2. The shock waves in the incoming flow in the form of an N-wave were generated by 150×7×0.13-mm two-dimensional roughness provided on the side wall of the T-325 wind tunnel. It was confirmed

The study is aimed at determining the position of the laminar-turbulent transition in subsonic and transonic two-dimensional boundary layers with the use of a novel software package LOTRAN 2.0 developed by the authors. The package is based on the eN-method and employs numerical data of numerical simulations of the laminar flow performed by standard gas-dynamic software systems based on the Reynolds-averaged

In the present paper, we report on the results of a study that was performed as part of the program for developing a method for calculating the flow and the mass-flow-rate coefficient in narrow cylindrical bleed channels under conditions of impingement of a thick boundary layer. For setting the boundary conditions at the inlet boundary of the computational domain, we used the pressure and temperature

On the basis of the Reynolds-averaged Navier-Stokes equations closed by the shear stress transport model with the consideration of streamline curvature, turbulent flow acceleration in the channel with inclined single-row oval-trench dimples, earlier found in the laminar regime, has been revealed. It is shown that the velocity in the flow core increases up to 1.4 times when dimples are densely packed

The flow structure in a high-speed gas jet released from the nozzle of a promising liquid-fuel spray-type burner is studied experimentally and theoretically. The velocity distribution in a single-phase gas flow is measured by means of particle image velocimetry (PIV) at various operating parameters. Using the one-dimensional isentropic flow approximation, the gas-dynamic parameters are estimated for

A thermodynamic description of the Ranque effect is given. Inclusion of expansion and compression into the energy exchange process provides a rational explanation to the effect observed. These works are performed by small portions of the gas in polytropic processes. Rotational motion of the gas and the presence of irreversibility in the expansion and compression processes are responsible for energy

The paper presents the results of an experimental study of energy production in the Couette-Taylor heat generator with independent rotation of cylinders: the system is applied to solving the problem of direct conversion of wind energy into thermal energy. The system consists of two nested multicylinder rotors. The regimes for two counter-rotating rotors are studied. The study is focused on the rotor

In this study, the effects of different thermo-chemical models on the macroscopic parameters of the flow behind a strong shock wave have been examined. The effect of the geometric average temperature proposed by Park and the effect of the electronic energy are also presented, and two CVD vibration-dissociation coupling models including those of Park and Kuznetsov are also examined and used for comparison

The results of numerical simulations of a jet discharging from a narrow slit at low Reynolds numbers Re are presented. A comparison with the data of laboratory experiments is performed, and it is shown that steady numerical solutions with increasing Re transform into unsteady solutions with self-excitation of sinusoidal instability. Lateral oscillations are superimposed at the inlet section, and their

The theoretically calculated dependence of the sizes of the main and satellite droplets on the dimensionless wave number of the perturbation of the surface of the Newtonian fluid jet is proved experimentally. It is also shown that an increase in the fluid viscosity significantly changes the dynamics of development of capillary waves in the jet and the mechanism of formation of satellite droplets.

Results of a pioneering experimental study of the cold spray method used for spraying aluminum traces onto the surface of a brittle erodible material (like brick) are reported. The spraying is performed using a sonic nozzle. Particle velocities near the axis of the two-phase jet are measured, and an approximating formula is derived to describe the dependence of the particle velocity on the stagnation

The preparation of a titanium composite powder containing high-melting TiN nanoparticles using an electric-arc plasma torch is studied. Using an Evo MA15 electron microscope (Carl Zeiss) and a DRON-4.0 diffractometer, both the surface morphology and the internal structure of powder particles are investigated, an X-ray phase analysis of these particles is performed, and a distribution map of the elements

The paper describes a theoretical study on the influence of filtration of a mixture of gaseous products of pyrolysis and water vapor on the dynamic of ignition of coal-water fuel particles under conditions of high temperature heating. The developed mathematical model offers simulation of the process of ignition of coal-water fuel droplets under conditions close to the furnace space (characterized by

Ice layer melting on a vertical substrate heated by a radiation source in the form of a halogen lamp is simulated numerically in a single-phase formulation of the Stefan problem. Ice is presented in the form of a clear, non-scattering, selectively absorbing material with two spectral bands of volume absorption. The computational model takes into account the selective nature of the radiation source

Various issues of increasing the thermodynamic efficiency of generation of produced energy carriers, such as water, hydrogen or compressed air are considered. The proposed technology, called multi-generation, is based on the creation of energy complexes consisting of generation facilities and consumers. The task of generation facilities is to manufacture, along with the traditional energy carriers