Volume 91, №3
MATHEMATICAL MODELING OF NONSTATIONARY SEPARATION PROCESSES IN A CASCADE OF GAS CENTRIFUGES FOR SEPARATION OF TUNGSTEN ISOTOPES
We have developed and program-realized a mathematical model of nonstationary separation processes proceeding in cascades of gas centrifuges for separation of multicomponent isotope mixtures. With the help of this model we have calculated the parameters of nonstationary separation processes proceeding in the cascades of gas centrifuges for tungsten isotope separation. It has been shown that the model adequately describes the nonstationary processes in the cascade and is suitable for calculating their parameters during separation of multicomponent isotope mixtures.
Author: A. A. Orlov, A. A. Ushakov, V. P. Sovach, and R. V. Malyugin
Keywords: gas centrifuge, multicomponent isotope mixture, cascade, separation, modeling, isotope, nonstationary process.
INVESTIGATION OF THE FORMATION MECHANISM AND THE MAGNITUDE OF SYSTEMATIC ERROR OF THERMOCOUPLE MEASUREMENTS IN HIGH-TEMPERATURE HEAT SHIELD AEROSPACE MATERIALS
The main factors infl uencing the systematic error of contact temperature sensors in a nonstationary thermal experiment have been determined, and its formation mechanisms have been analyzed. By comparison of the experimental data and the results of simulation, it has been established that, in highly porous heat-resistant materials, errors in thermocouple readings are determined by two differently directed mechanisms — advanced heating of the thermocouple by the radiant heat fl ux and the decrease in the conductive heat fl ux due to the additional heat resistance in the region of its contact with the sample. These mechanisms provide correction of the error and difference between the radiant and conductive heat fl uxes. From the results of the analysis, certain features of the error formation process at various distances from the heated surface of the sample have been established and quantitative relations for error magnitudes have been obtained.
Author: O. M. Alifanov, V. V. Cherepanov, and A. V. Morzhukhina
Keywords: highly porous materials, thermal fi eld, nonstationary experiment, mathematical modeling, error formation mechanism, comparative analysis, approximation
INFLUENCE OF THE METHOD OF ATTACHING SURFACE THERMOCOUPLES ON THE ERROR OF TEMPERATURE DETERMINATION IN TESTING CERAMIC MATERIALS ON RADIATIVE HEATING INSTALLATIONS
A procedural error of measuring the temperature on the ceramic material surface in testings carried out on radiative heating installations has been estimated. Different methods of attaching contact temperature sensors are investigated. Using mathematical simulation accounting for the thermophysical properties of all materials, good qualitative and quantitative agreement between calculated and experimental values of temperature has been obtained in the temperature sensor–sample system. Recommendations for reducing the error of measuring the frontal surface of samples in carrying out thermal tests on a radiative heating stand are given.
Author: S. A. Anuchin, A. V. Lanin, P. V. Prosuntsov, M. N. Kordo, M. O. Zabezhailov, and M. Yu. Rusina
Keywords: procedural error of temperature measurement, thermal testing, radiative heating, quartz ceramics
MECHANICAL MATERIAL TESTS BY THE NANOINDENTATION METHOD AT VARIOUS INDENTER AND SPECIMEN TEMPERATURES
Theoretical and experimental studies have been made of the nonisothermal contact interaction of an unsharpened conical indenter and an elastic material with an inhomogeneous surface layer. A relevant contact problem of thermoelasticity with arbitrarily changed thermomechanical characteristics in the depth of the surface layer has been formulated. To solve the boundary-value problem, the apparatus of integral Hankel transforms is used. With the use of the asymptotic method, a numerical-analytical approximated solution of the problem has been constructed, the values of the corresponding heat fl ux and of the half-space surface displacement have been determined, and the values of contact stresses beneath the die have been found. The developed model is used to estimate the value of indenter displacement caused by the thermoelastic deformation of the specimen. The results of the experiment on nonisothermal indentation of the prepared specimen of steel 40Kh on a Nanotest 600 facility are presented. The application of nanoindentation for investigations of mechanical properties of materials at high temperatures is discussed.
Author: L. I. Krenev, S. S. Volkov, E. V. Sadyrin, T. I. Zubar, and S. A. Chizhik
Keywords: nanoindentation, heating, nonisothermal contact, contact problem, mathematical modeling
INTENSIFICATION OF HEAT EXCHANGE IN THE REGENERATIVE COOLING SYSTEM OF A LIQUID-PROPELLANT ROCKET ENGINE
This paper considers various methods of intensifi cation of the heat exchange in the regenerative cooling system of a liquid-propellant rocket engine. Experimental data on hydraulic resistance and heat transfer coeffi cients in different cooling tracts are presented. A natural hydraulic experiment has been performed on the chamber of the liquid-propellant rocket engine, which confi rmed the calculations. The effi ciency of porous tracts with interchannel transpiration of the coolant and the effi ciency of tracts with coplanar channels have been shown.
Author: F. V. Pelevin, N. I. Avraamov, N. Ya. Ir′yanov S. A. Orlin, V. V. Lozovetskii, and A. V. Ponomarev
Keywords: fi nned cooling tracts, artifi cial roughness, coplanar channels, porous mesh metal, hydraulic resistance, one-dimensional and two-dimensional intermesh fi ltration of coolant, anisotropy, heat exchange effi ciency
SOLUTION OF AN INVERSE STEFAN PROBLEM IN ANALYZING THE FREEZING OF GROUNDWATER IN A ROCK MASS
A one-dimensional inverse Stefan problem is formulated in cylindrical coordinates. The problem is of interest in the analysis of freezing a mass of rock and forming an iced rock barrier around a single freezing column in building shafts as well as solving the problem of controlling the process of thawing. Additional conditions in the formulation of the inverse problem are the data of experimental measurements of temperatures in thermal boreholes located at a certain given distance from a freezing column and the magnitudes of temperatures and of the cold-carrier fl ow rate in freezing columns. An analytical expression is presented for the functional that determines the measure of proximity of the obtained solution to the exact one. A numerical method has been developed for solving the posed inverse problem by minimizing the functional.
Author: L. Yu. Levin, M. A. Semin, and A. V. Zaitsev
Keywords: iced rock barrier, coeffi cient inverse Stefan problem, minimization of functional, freezing column, controlling-thermal borehole, mass of rock, phase transition, building of shafts.
VORTEX INTENSIFICATION OF THE HEAT EXCHANGE IN THE LAMINAR FLOWS OF AIR AND M-20 OIL AROUND CIRCULAR AND ELLIPTICAL CYLINDERS
A comparative analysis of the laminar fl ows of air and M-20 oil around a circular cylinder and an elliptical cylinder with a ratio between its semiaxes of 0.3:0.5, located at right angles to an incident fl ow, at Re = 60 has been performed. The thermal and hydrothermal effi ciencies of the vortex intensifi cation of the heat exchange in these fl ows in the case of moderate heating of the cylinders were estimated.
Author: S. A. Isaev, Yu. V. Zhukova, I. A. Popov, and A. G. Sudakov
Keywords: laminar fl ow, vortex heat exchange, circular elliptical cylinders, air, oil
INFLUENCE OF THE PRESEPARATION FLOW STRUCTURE ON THE CHARACTERISTICS OF THE SEPARATION REGION BEHIND A BACKWARD-FACING STEP
This paper presents the results of investigations of the infl uence of the separated fl ow structure behind a rib located before the edge of the backward-facing step on the parameters of the separation region behind it. Numerical investigations were carried out by the method of large eddy similution in a plane air channel. The velocity of the developed turbulent fl ow at the inlet to the channel was assumed to be 25 m/s with a level of initial turbulence for three velocity components of 5%. The Reynolds number calculated by the initial velocity and the step height was 15,500. It has been shown that the creation of a preseparation region causes the two-dimensional fl ow to transform into a three-dimensional one before the edge of the back-facing step with the formation of nonuniform verticity along its length. This restructuring of the fl ow leads to an increase in the inhomogeneity of velocity parameters in the separated mixing layer. The fl ow expansion behind the step increased and was accompanied by local separation on the upper wall of the channel. The two separation regions caused a rapid growth of pulsations throughout the channel behind the step.
Author: V. L. Zhdanov, D. A. Ivanov, Ya. I. Smul′skii, and V. I. Terekhov
Keywords: plane channel, backward-facing step, rib, turbulent separation, separation structure
ON THE THEORY OF SLOPE FLOWS
Paradoxical properties of the classical Prandtl solution for fl ows occurring in a semibounded liquid (gaseous) medium above an infi nite homogeneously cooled/heated inclined plane are analyzed. In particular, the maximum velocity of steady-state slope fl ow is independent, according to this solution, of the angle of inclination. Consequently, there is no passage to the limit to the case of zero angle where the cooling/heating is unlikely to give rise to homogeneous horizontal fl ows. It is shown that no paradoxes arise if we do not consider buoyancy sources of infi nite spatial scale, which act infi nitely long. It follows from the results that, in particular, the solution of the problem for a semibounded medium above a homogeneously cooled surface in the gravity fi eld is unstable to small deviations of this surface from horizontal.
Author: L. Kh. Ingel′
Keywords: slow fl ows, analytical solutions, Prandtl model, asymptotics at small angles of inclination, thermal inhomogeneities
SIMPLIFIED ALGORITHM FOR NUMERICAL SOLUTION OF LIQUID FLOW EQUATIONS
An algorithm is suggested for numerical solution of differential equations for velocity and pressure on a staggered grid. The algorithm ensures unconditional convergence of iterations for a correction to pressure and without it.
Author: V. A. Kuznetsov
Keywords: mathematical model, incompressible liquid, velocity, pressure, correction to pressure, computational algorithm
FEATURES OF HIGH-VELOCITY PENETRATION AND MOTION OF SUPERCAVITATING KINETIC STRIKERS IN WATER
Consideration is given to conditions ensuring stable high-velocity motion of supercavitating kinetic strikers in water. To investigate the stressed-strained state and a possible destruction of solid bodies during the motion in water and in interaction with underwater barriers of various types, the authors carry out mathematical modeling based on a unifi ed methodological approach of the continuum mechanics. The range of the velocities under study is 500–1590 m/s. Results of the group start of supercavitating strikers are given
Author: V. V. Burkin, R. N. Akinshin, S. A. Afanas′eva, I. L. Borisenkov, A. N. Ishchenko, M. V. Khabibullin, A. V. Chupashev, and N. T. Yugov
Keywords: water, supercavitating kinetic strikers, barrier, high-velocity penetration, stability of motion, experimental mathematical modeling
ON THE THEORY OF ACOUSTIC SOUNDING OF TUBULAR CHANNELS CONTAINING DEPRESSURIZATION PORTIONS
A study is made of the evolution of pressure perturbations that propagate in a tubular channel fi lled with liquid or gas and having a damaged portion in the form of fairly large slots when their hydraulic resistance is minor. For this purpose, the authors have adopted a mathematical model taking account of viscous friction and of the transfer of heat in a thin layer of the liquid (or the gas) near the wall. Based on this model, dispersion relations have been obtained for the processes of propagation and refl ection of harmonic waves from the damaged portion. An analysis has been made of the dependences of the phase velocity, the attenuation factor, and also the coeffi cients of refl ection and transmission on the circular frequency, the physical properties of the liquid or the gas, and also the size of damage. The authors have presented results illustrating the dynamics of pulsed signals as a function of the distance to the damaged portion from the inlet cross section of the channel, the damage scale, and of the form of the medium (liquid or a gas) in the channel.
Author: V. Sh. Shagapov, É. V. Galiakbarova, and Z. R. Khakimov
Keywords: harmonic wave, phase velocity, attenuation factor, thermal dissipation, pressure pulse, acoustic impedance, transmission and refl ection coeffi cients
THREE-PARAMETER MODEL OF TURBULENCE FOR HIGH-VELOCITY FLOWS
A formulation of a modernized version of the three-parameter model of turbulence developed earlier by the present authors for calculating high-velocity fl ows is presented in the paper. The modernized model of turbulence allows one to calculate both free and near-wall fl ows. The distinctive features of the model are the application of a separate equation for velocity fl uctuations directed normally to streamlines, as well as of special functions of the gradient Mach number to account for compressibility. The model described was verifi ed on a number of test problems. The results obtained agree well with experimental data.
Author: A. M. Molchanov, L. V. Bykov, and D. S. Yanyshev
Keywords: turbulence, high-velocity fl ows, mathematical simulation, compressibility
PREDICTION OF HEAT TRANSFER DEVELOPMENT IN A SMOOTH TUBE
The heat transfer characteristics in a smooth tube are studied. Based on the available experimental data, a new correlation is proposed to predict the heat transfer coeffi cients inside tubes of different lengths. The predicted results show that for a range of L/D from 26.31 to 58.14, the heat transfer coeffi cient may be reduced by 20.56% and increased by 13.31% at the beginning and at the end of this range, respectively. The results obtained from the proposed correlation are compared with other analytical and experimental data, and satisfactory agreement is found.
Author: D. Sahel,a H. Ameur,b R. Benzeguir,a and Y. Kamlaa
Keywords: heat transfer characteristics, smooth tube, analytical correlation, channel length.
INFLUENCE OF THE DRAG COEFFICIENT OF PARTICLES ON THEIR DISTRIBUTION IN A TWO-DIMENSIONAL ACOUSTIC RESONATOR
A numerical study is made of the plane problem on the drift of a group of particles in the rectangular-resonator′s standing wave induced by harmonic oscillations of the left boundary at the fi rst resonant frequency. The infl uence of the drag coeffi cient of particles on the dynamics and distribution of the particles in the resonator has been investigated. At certain drag coeffi cients, regions of acoustic capture of particles have been found. In these regions, the inherent particle drift is counterbalanced by the transfer by acoustic streaming. It has been shown that the particles share a common tendency to drift to resonator walls, where the gas velocity is minimum.
Author: D. A. Gubaidullin, P. P Osipov, and R. R. Nasyrov
Keywords: acoustic streamings, particle drift, acoustic traps.
MIXING OF BOTTOM AND TANGENTIAL AIR IN A CYCLONE-FLUIDIZED BED CHAMBER
An experimental investigation of the characteristic features of mixing of the bottom- and tangentially blown air at different temperatures in a cyclone-fl uidized bed chamber with varying operational and geometric parameters has been carried out. Their infl uence on the temperature fi elds in the chamber has been established. Optimal values of the pinch diameter, bottom-blown fraction of air, and of the air fl ow rate that yield the most uniform temperature distribution in the chamber volume are determined.
Author: E. A. Pitsukha, Yu. S. Teplitskii, and É. K. Buchilko
Keywords: cyclone-bed chamber, fl uidized bed, bottom air blowing, tangential air blowing, mixing, temperature, diffusion, mass transfer
HEAT AND MASS TRANSFER IN CONVECTIVE WOOD-DRYING PLANTS
Geometric and physicomathematical models of the problem of convective drying of lumber in a chamber drier have been presented. Its solution with the ANSYS Fluent program has been given. The process of heat and mass transfer in the indicated plant in the process of drying of wood in it has been described. The developed calculation procedure can be used to determine optimum regimes for the drying of wood.
Author: V. A. Sychevskii
Keywords: wood, lumber, woodworking, convective drying plant, heat and mass transfer, geometric and physicomathematical modeling, numerical calculation, computational experiment
SEPARATION OF NONSPHERICAL PARTICLES IN A HYDROCYCLONE
On the basis of hydrodynamic equations, the structure of the fl ow of a suspension in a hydrocyclone and the separation of isothermal nonspherical particles in it were investigated numerically. A mathematical model is proposed for calculating the separation parameters of the indicated particles and their concentration fi eld. It is shown that the most marked dependence of the separation parameters of suspension particles on their shape is characteristic of the particles whose sizes fall within the range 10 < dp < 50 μm and that the separation of such particles should be conducted taking into account the possible deviation of their shape from the spherical one.
Author: O. V. Matvienko, and A.O. Andropov
Keywords: hydrocyclone, separation, multiphase turbulent fl ows, computational hydrodynamics
EVAPORATING MENISCUS AT THE BOUNDARY BETWEEN THREE PHASES
A method is proposed for approximate solution of the problem on the hydrodynamics of the evaporating meniscus of a thin liquid fi lm on a heating surface. This method is based on reduction of the initial differential equation for the hydrodynamics of the meniscus. The interaction of the intermolecular, capillary, and viscous forces and the molecular-kinetic effects at the boundary between the meniscus and the adsorbed thin liquid fi lm were analyzed. The analytical solution obtained allows one to determine the geometrical parameters of such a meniscus and the heat fl ow through it.
Author: Yu. B. Zudin, D. S. Urtenov, and Yu. N. Éikhorn
Keywords: hydrodynamics, evaporating meniscus, liquid fi lm, molecular-kinetic effects, analytical solution, geometric parameter
INFLUENCE OF A LOCAL TEMPERATURE CHANGE OF A METAL MELT ON ITS ELECTROVORTEX MOTION IN A BOUNDED VOLUME
The infl uence of a local change in the temperature of a metal melt in a bounded volume of a dc arc furnace with a bottom electrode on the structure of its convective and electrovortex fl ows has been modeled numerically with account taken of the crystallization of the metal. The motion of the metal melt was described by magnetic-hydrodynamics equations for a nonisothermal liquid. The strategy of solution of the indicated problem within the framework of standard packages of applied programs has been developed. It has been shown that the local temperature change of the metal melt changes substantially the structure of its convective and electrovortex fl ows in the immediate vicinity of a point of the furnace with a lower-than-average temperature and exerts a minor infl uence on the vortex motion of the melt as a whole throughout the furnace′s volume.
Author: O. V. Kazak
Keywords: numerical modeling, vortex and convective fl ows, metal melt, Lorentz force, dc arc furnace
ICE FORMATION IN THE FORM OF ICICLES AND UTILIZATION OF HEAT OF CRYSTALLIZATION FOR AIR HEATING
This paper presents the results of investigations of ice formation in the form of icicles on horizontal wire and tubular attachments of various diameters. We have obtained the dependence of the relative mass of built-up ice on the duration of the process of its build-up at a constant fl ow rate of water and the dependences of the mass of built-up ice on the diameter of the tube and the material from which it is made. It has been shown that the application of tubes from low-wettability polymer materials promotes intensifi cation of the process of ice formation. A pilot air-heater is presented, which can be used for the needs of ventilation of a building of area 400 m2 or in systems with thermal pumps, and its operation under real conditions in regimes with natural and forced convection has been demonstrated.
Author: I. I. Pukhovoi and A. M. Postolenko
Keywords: crystallization heat, ice build-up, thermal pump, air heating
EXTINGUISHING A GROUND FOREST FIRE BY SPRAYING WATER OVER ITS EDGE
An experimental investigation of the physiochemical processes occurring in the localization of a ground forest fi re by spraying of water over its edge has been performed. Several schemes of formation of a barrage, comprising a moistened forest combustible material and an aerosol curtain, for such a fi re are presented. It is proposed to spray water in the region upstream of the combustion front, in the region of the combustion front, and simultaneously in these regions. The conditions of extinguishing of a model ground forest fi re by spraying of water over its edge were determined depending on the velocity of movement of the combustion front, the density of spraying of the fi re hotbed, the dispersivity of the water used for the spraying, and the width of the fi re barrage. The times of termination of the movement of the front of fl ame combustion of a forest combustible material, complete burn-out of this material, and cessation of its thermal decompositions in the case of formation of a fi re barrage around it were estimated. The parameters of the spraying of water over the edge of a ground forest fi re, providing its localization and suppression, were determined.
Author: R. S. Volkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords: forest combustible material, hotbed of fi re, thermal decomposition, fl ame combustion, localization, water spraying, thermal decomposition
THERMODYNAMIC ANALYSIS OF PROSPECTS FOR USING ALUMINUMAND BORON-CONTAINING CLUSTERS IN COMBINED HIGH-ENERGY FUELS
The high enthalpies of combustion of atomic clusters Aln, Bn, and Cn (n = 1, 2, …, 7), AlnCm and BnCm (n = 1, …, 5 and m = 1, …, 5), AlnBm (n + m ≤ 7), and AlnHm and BnHm (n = 1, …, 4 and m ≤ 12) have been assessed. The specifi c energy release, the fi nal adiabatic temperature, and the effectiveness of the combustion products of fuel mixtures based on kerosene, dimethyl ether, and ethyl alcohol with small additions of such clusters have been determined under the assumption of attaining a thermodynamic equilibrium in their combustion products. An analysis has been made of the potentials of small aluminum- and boron-containing clusters for use in improving thermochemical properties of the fuels. It has been shown that adding such clusters to traditional fuels in the amount of 10% of the fuel mass can increase the specifi c energy release of the fuel by 2 MJ/kg, the effectiveness of combustion products of the fuel by 10%, and their fi nal temperature by 200 K
Author: B. I. Lukhovitskii and A. S. Sharipov
Keywords: atomic clusters, combined fuels, thermodynamic analysis, heat of combustion
INFLUENCE OF THE TYPE OF CATALYSTS ON THE FORMATION OF A SUPERHYDROPHOBIC CARBON NANOMATERIAL IN HYDROCARBON FLAMES
The authors present results of synthesis of superhydrophobic soot in fl ames of various hydrocarbons (methane, propane, butane, and polyethylene waste) using metallic catalysts of the gauze type from nichrome wire and of the honeycomb type from nickel plates, and also natural aluminosilicates. An analysis of hydrophobic characteristics of the obtained samples of soot has shown a substantial infl uence of the catalysts on its hydrophobic properties. The best samples of soot with a wetting angle larger than 160o were obtained during the combustion of gaseous hydrocarbons with the use of the honeycomb-type nickel catalyst. Soot samples obtained during the combustion of propane with a honeycomb-type nickel catalyst had a wetting angle within 160–165o , suggesting the presence of superhydrophobic properties in the soot. These samples were characterized by the large degree of graphitization (≈20%), which is due to the infl uence of metallic nickel on the structure of formed soot particles.
Author: G. T. Smagulova, M. Nazhipkyzy, B. T. Lesbaev, A. E. Bakkara, N. G. Prikhod′ko, and Z. A. Mansurov
Keywords: superhydrophobic soot, catalysts, hydrocarbons, synthesis.
INFLUENCE OF WALL CONDUCTIVITES ON A FULLY DEVELOPED MIXED-CONVECTION MAGNETOHYDRODYNAMIC NANOFLUID FLOW IN A VERTICAL CHANNEL
A fully developed mixed-convection nanofl uid fl ow in a vertical channel with variable thermal and electrical wall
conductivities in the presence of a uniform transverse magnetic fi eld is studied. The working fl uid is a homogeneous
mixture of a base fl uid (water) and metallic nanoparticles of three different kinds, namely, copper, alumina, and
titanium dioxide. The fl uid is also electrically conducting in the presence of an applied magnetic fi eld. The fl ow is
characterized by a moderate magnetic Reynolds number. An induced magnetic fi eld is present. The effects of the
pertinent parameters on the nanofl uid temperature, velocity, and induced magnetic fi eld strength, as well as on the
shear stress and heat transfer rate at the channel wall, are shown. In the case of a negative vertical temperature
gradient (heating from below), there exists a critical Rayleigh number at which the fl uid becomes unstable. This
number is also found as a function of the wall conductivities.
Author: S. Das, B. Tarafdar, R. N. Jana, and O. D. Makinde
Keywords: fully developed fl ow, mixed convection, nanofl uids, wall conductivity, channel
HEAT TRANSFER IN THE COURSE OF MAGNETORHEOLOGICAL POLISHING
An investigation of thermal processes in the course of magnetorheological polishing has been carried out. Physical and mathematical description of heat transfer from a treated surface to a polishing tool is given with consideration of the specifi cs of the rheological and thermophysical properties of the tool acquired by it in a magnetic fi eld in the zone of treatment. An analytical estimate of the thermal state of a magnetorheological abrasive tool and of a treated workpiece surface is given. The temperatures of the workpiece surface and of the magnetorheological abrasive tool in the zone of their contact interaction in an inhomogeneous magnetic fi eld are determined experimentally. The increase in the temperature of the treatment zone by ΔT = 6.6o C at an absolute maximum temperature of T = 299.6 K is recorded experimentally, with the measured temperature gradient comprising 0.073 K/s.
Author: M. L. Levin and A. L. Khudolei
Keywords: magnetorheological polishing, thermal conductivity, heat release, temperature regime, treatment zone
ELECTRICAL AND MAGNETIC PROPERTIES OF A KEROSENE-BASED MAGNETIC FLUID SUBJECTED TO THE ACTION OF ELECTRIC AND MAGNETIC FIELDS
A complex investigation of the electrical and magnetic properties of the most abundant magnetic fl uids of the type of magnetite in kerosene with oleic acid as a stabilizer has been performed with the aim to establish the generality of the processes of magnetization and polarization of these fl uids. The permittivity and magnetic susceptibility of such fl uids, which are their most structurally-dependent parameters carrying information on the mechanism of magnetization and polarization of a fl uid, were determined.
Author: V. I. Zubko, Yu. I. Dikanskii, D. V. Zubko, S. A. Kunikin, and G. I. Sitsko
Keywords: kerosene-based magnetic fl uid, magnetization, magnetic susceptibility, magnetic and electrical properties
DETERMINATION OF THE THERMODYNAMIC PROPERTIES OF THE CYCLOHEXANE + n-OCTANE + n-HEXADECANE LIQUID MIXTURE BY THE ACOUSTIC METHOD
The propagation of sound in the ternary cyclohexane + n-octane + n-hexadecane mixture at temperatures of 298–433 K and pressures of 0.1–100.1 MPa was investigated experimentally. The maximum error in measuring the velocity of sound in this mixture was 0.1%. Experimental data on the velocity of sound in such a mixture were obtained for the fi rst time. On the basis of these data, the density, the isobaric expansion coeffi cient, the isobaric and isochoric heat capacities, and the isothermal compressibility of the indicated ternary mixture of three compositions at a temperature of 298–348 K and a pressure of 0.1–100 MPa and the deviation of the velocity of sound in it from the ideal one were determined. With the use of a number of semiempirical equations, the deviation of the velocity of sound in this mixture from the ideal one was estimated on the basis of the data on the velocity of sound in its pure components and in their binary compounds. A good agreement between the calculation and experimental data has been obtained. A table of the thermodynamic properties of the cyclohexane + n-octane + n-hexadecane mixture is presented
Author: T. S. Khasanshin, N. V. Golubeva, V. S. Samuilov, and A. P. Shchemelev
Keywords: cyclohexane, n-octane, n-dodecane, n-hexadecane, binary and ternary mixtures, velocity of sound, density, heat capacity, compressibility
DETERMINATION OF THE COEFFICIENT OF THERMAL AND MOISTURE CONDUCTIVITY OF WOOD BY THE TRANSIENT MOISTURE CURRENT METHOD
Consideration is given to the method of determining the coeffi cient of thermal and moisture conductivity of wood by measuring the transient moisture current in its cross grains. Results of experiments conducted with birchwood are in good agreement with analogous data obtained earlier
Author: M. A. Goreshnev, F. G. Sekisov, and O. V. Smerdov
Keywords: wood, thermal- and moisture-conductivity coeffi cient, transient moisture current method
INVESTIGATION OF THE MOLECULAR STRUCTURE OF THE "POLYACRYLAMIDE FLOCCULANT–H2O" SYSTEM FROM VISCOSIMETRY DATA
The dynamic viscosity of the system "polyacrylamide fl occulant–H2O" has been measured in the temperature interval 277–313 K. The dependence of the particle size on the ionic force of solutions has been investigated. The quantities characterizing the physicochemical properties of particles, such as the thickness of the diffusion layer and of the hydration sheath, have been determined. The interaction energy of particles of the high-molecular-weight compound in the solution has been studied. Results of purifi cation of model solutions of industrial wastewater have been given, which were obtained with the fractional-fl occulation technique. The characteristic of the investigation method in question has been presented, the basic classes of reactants have been described, and the mode of action of the substances has been substantiated.
Author: E. Yu. Shachneva and V. Ya. Khentov
Keywords: dynamic viscosity, fl occulant, ionic force of the solution, particle radius, diffusion-layer thickness, hydration-sheath thickness, molecular weight, interaction energy, fractional-fl occulation technique, purifi cation, wastewater