Volume 96, №4
USE OF ENTROPY-BALANCE EQUATIONS FOR ESTIMATING THE LIMITING CAPACITY OF THERMODIFFUSION CYCLES
The problem on the limiting capacity of the thermodiff usion cycles of separating a mixture was investigated using
the methodology of the fi nite-time thermodynamics. Expressions for the maximum effi ciency of such a cycle and its
limiting capacity, depending on the composition of the mixture separated, its temperature, and the heat fl ow used in
the cycle, have been derived. The boundary of the realizability range of the regime parameters of a thermodiff usion
cycle of separating a mixture was constructed and parametrized in the cycle effi ciency–heat consumption plan
Author:
A. A. Mazikov, I. A. Sukin, A. M. Tsirlin
Keywords:
thermodiff usion cycles, limiting capacity, thermodynamic-balance equations, maximum effi ciency, irreversibility factors
Page:
849
THERMODYNAMIC-PERFECTION CHARACTERISTICS OF HEAT-EXCHANGE SYSTEMS
Mathematical models of stationary heat-exchange systems, diff ering in the organization of the fl uid dynamics of the
fl ows in them, are presented. Expressions for the thermodynamic perfection characteristics of the heat exchange in
such a system (the heat load on the system, the entropy production in it, and its heat-transfer coeffi cient) and relations
between them, depending on the fl uid dynamics of the fl ows in the system, their organization, and the kinetics of heat
transfer in the system, have been derived. It is shown that the kinetics of heat exchange in a heat-exchange system
infl uences only the heat transfer in it.
Author:
A. M. Tsirlin, A. A. Mazikov
Keywords:
fl ows, irreversible heat exchange, thermodynamic perfection, fl uid dynamics, kinetics of heat exchange
Page:
858
OBTAINING HIGHLY CONCENTRATED MOLYBDENUM ISOTOPES ACCORDING TO A MULTISTAGE SCHEME IN A CASCADE OF GAS CENTRIFUGES
Consideration has been given to the distinctive features of multistep concentration of all the molybdenum isotopes
in a cascade with a varying type of stages as far as the number of gas centrifuges is concerned. A computational
experiment on separation of molybdenum hexafl uoride was conducted. A procedure of calculation from the cuts of
partial fl ows of the stages was used which takes account of the dependence of the separation factors of gas centrifuges
on their feed fl ow and the fl ow-division coeffi cient. It has been shown that the high effi ciency of separation processes
is attained with a large number of stages and gas centrifuges and small feed fl ows of the cascade
Author:
V. A. Palkin
Keywords:
separation of isotopes, isotopes of molybdenum, separation cascade, gas centrifuge, separation factor
Page:
870
ON CALCULATION OF THE COST OF ENRICHED PRODUCT OF SEPARATING PRODUCTION
The problem of calculating the cost of enriched products in cascades with several external feed and selection fl ows
is considered, with the schemes of the latter being not reduced to a set of cascades with one feed. The calculation is
based on the accepted condition that the total power of cascade separation was completely distributed between the
isotopic values of the external selection fl ows. It is shown that for such cascades the calculation methods successfully
used for single-fed cascades do not make it possible to fulfi l this condition and correctly determine the cost of
commercial products. A form of the potential is proposed that makes it possible to meet this requirement and calculate
the cost of all enriched products
Author:
A. I. Izrailevicha, V. A. Palkin
Keywords:
separation of isotopes, separation cascade, commodity fl ows, isotope value, separation potential
Page:
877
SQUARED-OFF CASCADES OPTIMIZATION TO SEPARATE STABLE ISOTOPES UP TO HIGH-ENRICHED USING INTELLIGENT PSO, WOA, AND DA ALGORITHMS
This paper suggests the optimized squared-off cascades (SOCs) with a certain number of gas centrifuges (GCs) to
separate stable isotopes, such as the lightest and heaviest isotopes of molybdenum (100Mo and 92Mo) up to 99.9%
richness, using the particle swarm optimization (PSO), the whale optimization algorithm (WOA), and the dragonfl y
algorithm (DA). To do this, the SOC-PSO, SOC-WOA, and SOC-DA codes are developed to optimize the parameters
of SOCs. Then the performances of these codes in optimizing SOCs for separating each of 92Mo and 100Mo isotopes
are compared based on the recovery factor, the feed intake, and the amount of production with the use of 120 gas
centrifuges. The recovery coeffi cients of SOCs for 92Mo and 100Mo isotopes obtained by the SOC-PSO code are 82
and 80%, respectively. Finally, the performances of the PSO, WOA, and DA algorithms in optimizing SOCs for each
of light and heavy isotopes are compared, and a higher effi ciency of the PSO algorithm is revealed
Author:
F. Ardestani, J. Safdari, M. H. Mallah
Keywords:
squared-off cascade (SOC), gas centrifuge (GC), multicomponent separation, particle swarm optimization (PSO), whale optimization algorithm (WOA), dragonfl y algorithm (DA).
Page:
882
FORMATION OF OXIDES UPON THERMAL DEBINDING AND THEIR ROLE IN OBTAINING REACTION-BONDED SILICON CARBIDE
A study has been made of the formation of silicon oxides on the surface of silicon carbide upon thermal removal of
a paraffi n binder from a powder silicon-carbide casting in an air atmosphere at a temperature of 600–900o
C. An
optimum temperature of 630o
C of the process was determined which allows obtaining the SiC base with maximum
porosity and a mechanical bending strength of 0.5 MPa. It has been shown that surface oxides are reduced by solid
carbon in the process of manufacture of the composite C–SiC at the stage of pyrolysis in vacuum at 1600o
C and
exert no infl uence on the following process of liquid-phase C–SiC siliconizing when reaction-bonded silicon-carbide
ceramics is obtained. The amount of solid carbon expended on reducing the oxides makes up an appreciable part
of the carbon introduced into the pores of the SiC base when C–SiC is prepared for siliconizing and must be taken
account of as a correction in calculations of the composition of the intermediate and fi nal materials of the ceramics
Author:
P. S. Grinchuk, M. V. Kiyashko, M. O. Stepkin, A. V. Akulich, D. V. Solovei, S. M. Danilova-Tret′yak
Keywords:
silicon carbide, reaction-bonded ceramics, porosity, pyrolysis, oxidation, reduction
Page:
897
COMBUSTION OF KEROSENE IN A SUPERSONIC FLOW AT MACH NUMBER M = 1.7 UNDER THE ACTION OF GAS-DYNAMICAL PULSES
The combustion of kerosene in a model combustion chamber at the fl ow Mach number M = 1.7 and a stagnation
temperature of 1400 K is studied numerically. To ignite the fuel supplied through an axial injector and sustain its
combustion, a pulsed periodic gas-dynamical eff ect is applied. The Reynolds-averaged Navier–Stokes equations
are solved, which are closed by the k–ε turbulence model. Fuel combustion is reproduced using a single reaction.
Calculations are carried out for various channel lengths. The gas-dynamical structure of fl ow during unsteady
combustion of kerosene has been studied. The possibility of formation of a transonic fl ow regime has been investigated.
The power of gas-dynamical eff ect is determined.
Author:
V. P. Zamuraev, A. P. Kalinina
Keywords:
combustion of kerosene, supersonic fl ow, throttling jet, transonic regime
Page:
906
DISTINCTIVE FEATURES OF PROPAGATION OF THE FLAME OF A COAL–METHANE–AIR MIXTURE IN A CYLINDRICAL CHANNEL
A two-dimensional axisymmetric model of combustion of a coal–methane–air mixture has been constructed with
the approaches of the dynamics of two-phase reactive media. Numerical investigation into the regularities of
propagation of the combustion front in a cylindrical channel has been performed. The infl uence of the radius and
mass concentration of coal-dust particles on the velocity of propagation of the fl ame was shown. The acceleration of
the fl ame on reaching the channel′s lateral walls by the combustion front was demonstrated. The diff erence in fl ame
velocities was shown in the cases of open and closed right ends of the channel
Author:
K. M. Moiseeva, A. Yu. Krainov
Keywords:
gas suspension of coal dust, methane–air mixture, burning rate, numerical modeling
Page:
913
POSSIBILITIES OF AMPLIFYING THE ELECTROMAGNETIC FIELD AT THE POLES OF THE MICROWAVE DISCHARGE INITIATOR TO FORM DISCHARGES WITH A DEVELOPED STREAMER STRUCTURE
Various electrodynamic models of a combustion chamber are discussed, in which an initiated subcritical streamer
discharge is used to ignite the combustible mixture. To localize the discharge in the working chamber, initiators
based in half-wave electromagnetic vibrators with resonant properties are used. Based on numerical calculations,
the dependences of the structure of the electric fi elds forming the discharge on the geometric parameters of the
discharge initiator were obtained, and the issues of matching the dimensions of the chamber with the radiation
generator were considered. The ways of increasing the resulting electromagnetic fi eld in the region of the vibrator
for the formation of a discharge with a bulk structure are determined
Author:
P. V. Bulat, K. N. Volkov,a I. I. Esakov, P. B. Lavrov, A. A. Ravaev
Keywords:
microwave radiation, streamer discharge, electrodynamic model, plasma burning
Page:
922
INVESTIGATION INTO DISTINCTIVE FEATURES OF COMBUSTION OF HIGH-DENSITY PROPELLANTS UNDER THE CONDITIONS OF A MANOMETRIC BOMB
The combustion of a model high-density propellant (MHP) under the conditions of a closed volume has been
investigated. A description is given of the main components and mechanisms of the manometric bomb being
used. Procedures are described for determining the laws of propellant combustion in a manometric experiment,
and a comparison is made of computational-experimental data. The distinctive features of the formation of an
MHP combustion surface in various containers have been identifi ed and described. The dependences of the layer
combustion velocity of two model high-density propellants on pressure have been determined
Author:
K. S. Rogaev, A. N. Ishchenko, A. S. D′yachkovskii, N. M. Samorokova, E. Yu. Stepanov, A. V. Chupashev
Keywords:
manometric bomb, combustion law, model high-density propellant, paste propellant
Page:
928
NUMERICAL INVESTIGATION INTO THE PROPAGATION OF DETONATION WAVES IN INHOMOGENEOUS GAS SUSPENSIONS OF A MONOFUEL IN ABRUPTLY EXPANDING TUBES
The author has given results of a numerical investigation into the propagation of detonation waves in abruptly
expanding tubes that are fully or partially fi lled with the gas suspension of a monofuel. The infl uence of the parameters
of gas suspensions and a pipeline, and also transverse spatial nonuniformities of the concentration distribution of
particles in the tubes have been studied. It has been established that the critical value of height of a transverse spatial
nonuniformity decreases monotonically as the relative mass content of the suspension grows. Dependences of the
critical diameter of particles on their relative mass content have been given.
Author:
U. A. Nazarov
Keywords:
combustion, detonation, shock wave, detonation wave, combustion front of a particle, combustion front of a monofuel, pipeline, mass content of particles
Page:
939
SIMULATION OF THE SYNTHESIS OF COMPOSITE PARTICLES OF THE CORE–SHELL TYPE BASED ON CO-OXIDATION OF TITANIUM AND SILICON TETRACHLORIDES IN A PLASMACHEMICAL REACTOR UNDER CONDITIONS OF AGGLOMERATION OF BOTH COMPONENTS
Simulation of one-stage synthesis of composite nanoparticles of titanium dioxide and silicon dioxide in the working
zone of a plasmachemical reactor by the chloride method based on the joint oxidation of titanium and silicon
tetrachlorides was carried out. The developed synthesis model takes into account the possibility of aggregation not
only of titanium dioxide particles that form the cores of composite particles, but also of silicon dioxide particles
that do not participate in the formation of the shell. Comparison of the results of calculations by diff erent models is
carried out: the size of the cores, the thickness of the shell, and the number of particles of various types.
Author:
S. M. Aul'chenkoa, E. V. Kartaeva
Keywords:
titanium dioxide, silicon dioxide, composite particle, plasmachemical reactor, single-speed multicomponent medium, homogeneous and heterogeneous reactions, coagulation
Page:
947
NUMERICAL MODEL OF PRESSURE AND VELOCITY FIELDS IN AXISYMMETRIC FILTRATION IN AN IMPERFECTLY PENETRATED STRATUM
A mathematical model of pressure and velocity fi elds resulting from the infl ow of hydrocarbons to a well of fi nite
radius from partially penetrated reservoir beds has been presented. It is assumed that two-dimensional fl ow initiated
by an assigned depression in an imperfectly penetrated stratum is axisymmetric. A mathematical formulation of
the problem in cylindrical geometry on the pressure fi eld in an isolated isotropic homogeneous stratum whose
boundaries do not coincide with the boundary points of a perforation interval has been given. A fi nite-diff erence
model has been described on whose basis a program was made up for calculation of pressure and velocity fi elds in
the stratum and computational experiments were consducted which allowed identifying new regularities of fl ow of
practical importance that arise in actual oil and gas reservoirs.
Space–time dependences of the pressure fi eld in an oil and gas stratum and of the radial components and modulus
of fi ltration velocity of hydrocarbons have been shown, which illustrate the distinctive features of two-dimensional
fl ow with imperfect penetration of the stratum and basic diff erences from the well-studied case of plane radial onedimensional fl ow to the well of fi nite radius. Based on an analysis of the contour lines, new physical regularities of
the fl ow have been identifi ed that are associated with incomplete perforation of the thickness of the reservoir bed. By
the numerical experiments, it has been established that in axisymmetric fl ow in the stratum, vertical fl ows inevitably
arise which vanish at exit from the stratum into the well. It has been confi rmed that in homogeneous incompletely
penetrated reservoirs, intralayer crossfl ows arise in the near wellbore zone, and the radial component of fi ltration
velocity in two-dimensional axisymmetric fl ow in the imperfectly homogeneous isotropic stratum depends on the
vertical coordinate. This means that the infl ow to the well is not uniformly distributed over the stratum thickness,
and the modulus of the horizontal velocity component in all the curves peaks on the boundaries of the perforation
interval. In the case of two-dimensional fl ow at the center of the perforation interval equally distant from the upper
and lower boundaries of the oil and gas stratum, a minimum specifi c infl ow is observed.
Author:
A. I. Filippov, O. V. Akhmetova, M. R. Gubaidullin
Keywords:
fi ltration, imperfect penetration, piezoconductivity equation, two-dimensional fl ow, fi nite-diff erence program, pressure fi eld, velocity field
Page:
955
DETERMINATION OF THE RELAXATION COEFFICIENT DURING FILTRATION OF A HOMOGENEOUS LIQUID IN FRACTURED-POROUS MEDIA
An inverse problem of determining the relaxation coeffi cient in a simplifi ed model of relaxation fi ltration of a
homogenous fl uid in fractured-porous media is posed and numerically solved. To solve the problem, various methods
of identifi cation were used, in particular, the fi rst-order method, the modifi ed fi rst-order method, and the secondorder method. It has been established that this coeffi cient at various zero approximations with unperturbed initial
data is restored in almost four to six iterations. At a more remote initial approximation from the equilibrium point,
the iterative procedure converges to the shifted values of the unknown parameter. To obtain an unbiased estimate of
the desired parameter, a modifi ed fi rst-order method was used.
Author:
B. Kh. Khuzhayorova, É. Ch. Kholiyarov
Keywords:
relaxation coeffi cient, identifi cation method, inverse problem, homogenous liquid, relaxation fi ltration, fractured-porous medium
Page:
966
INVESTIGATION OF RADIATIVE-CONDUCTIVE HEAT TRANSFER BY NONCONTACT MEASUREMENTS. 2. APPROVAL OF THE COMPUTATIONAL-EXPERIMENTAL METHOD
An experimental installation for laser heating (ULN-1) has been developed to implement a technique for identifying
mathematical models of radiative-conductive heat transfer without using contact measurements. A substantiation of
the choice of the system components and of the procedure for its application is given. Approbation of the installation
and of the identifi cation technique was carried out on the example of determining the thermophysical characteristics
of a thin plate made of an opaque material.
Author:
A. V. Nenarokomov, S. A. Budnik, D. S. Semenov
Keywords:
heat transfer model, hyperthermia, biological tissues, inverse problem of heat exchange, experimental installation
Page:
980
CONVECTIVE DRYING OF FLAT FIBROUS MATERIALS
The kinetics of drying dense wool fabric in diff erent regimes has been studied experimentally. The massconducting (diff usion) properties of the fabric are determined depending on the content of moisture in it and its
temperature. For the convenience of engineering calculations, the obtained data on the mass conductivity of the
fabric are approximated by its dependences on moisture content and temperature. It has been established that
the kinetics of convective drying of a dense wool fabric is adequately described by A. V. Luikov′s model of heat
and moisture transfer subject to the dependence of the mass conductivity of the fabric on its moisture content and
the temperature of the drying agent. The proposed approach to the calculation of the kinetics of drying a dense
wool fabric, its moisture content, and its temperature can be used in the design of the processes of drying various
fabrics
Author:
M. K. Kosheleva, S. P. Rudobashta, O. R. Dornyak, M. K. Kosheleva,a S. P. Rudobashta,b O. R. Dornyak,
Keywords:
convective drying, kinetics, mass conduction, mathematical simulation, dense wool fabric
Page:
988
ON STRATIFIED FLOWS CAUSED BY SPATIAL INHOMOGENEITIES OF TRANSFER COEFFICIENTS
The previously unstudied mechanism of the emergence of stratifi ed fl ows caused by spatial inhomogeneities of
exchange coeffi cients is investigated analytically. In the calculations, a linear approximation is used with specifi ed
horizontally harmonic variations of the thermal conductivity coeffi cient of a relatively small amplitude. Explicit
analytical expressions are obtained for temperature perturbations of the environment and velocity of fl ows in it. The
possibility of intensifying such perturbations for some values of the medium parameters is shown.
Author:
L. Kh. Ingel
Keywords:
stratifi ed medium, spatially inhomogeneous exchange coeffi cients, buoyancy, diff usion, density flows
Page:
994
ASYMMETRY OF A FLOW WHICH IS DUE TO THE INTERACTION OF A COMPRESSION SHOCK WITH THE BOUNDARY LAYER ON A LONGITUDINALLY RIBBED SURFACE
Numerical investigations of the asymmetry of a fl uid fl ow in the channel of an air intake which is due to the interaction of a compression shock, generated by the shell ring of the air-intake channel, with the boundary layer on
the longitudinally ribbed lower surface of this channel have been performed on the basis of the Reynolds-averaged
Navier–Stokes equations and the SST k–ω model of turbulence. Data on the structure of the fl uid fl ow in such a
channel with a narrowing inlet part and a next part of constant cross section, the limiting fl ow lines on the longitudinally ribbed lower surface of the channel, and the profi les of the velocity of the fl ow and the total pressure in the
boundary layer in the channel have been obtained for the case where the Mach number of the fl uid fl ow incoming to
the channel is M = 4.
Author:
I. I. Mazhul′
Keywords:
numerical simulation, supersonic fl ow, rectangular channel, longitudinally ribbed surface.
Page:
999
DYNAMICS OF A PRESSURE WAVE IN A CYLINDRICAL CHANNEL WITH A RING BUBBLE ZONE
Results of investigations of the dynamics of a pressure wave in a cylindrical channel with a near-wall ring bubble
zones in a liquid are presented. The infl uence of the sizes of this zone, its dispersity, and the volumetric content of
bubbles in it on the amplitude of the pressure wave formed in the channel because of the action of the bubble zone
on the channel walls was determined.
Author:
I. K. Gimaltdinov, M. N. Galimzyanov, E. Yu. Kochanova
Keywords:
pressure wave, bubble cluster, focusing
Page:
1008
RANS AND LES COMPUTATIONS OF NATURAL CONVECTION IN A SQUARE CAVITY
Turbulent natural convection (Ra = 1.58·109
) in a confi ned 3D square cavity with two diff erentially heated side walls
are simulated numerically using the in-house EDF code (Code_Saturne) based on the unstructured fi nite volume
solver. The objective of the present work is to investigate the performance of the low-Reynolds-number models
known by their good suitability for the near-wall treatment. The low-Reynolds-number models, shear stress transport
(SST) k–model, –f model which is a developed version of the original –2 f model, and the LES (large-eddy
simulation) technique are used, and the results of their using are compared with the experimental benchmark data.
The numerical results show quantitative and qualitative agreements. In general, the SST k– model gives good
predictions for the temperature profi les, and the –f model is more accurate for the velocity profi le prediction. This
is mainly due to the good resolution of the turbulence properties in the near-wall region and to the ability to mimic
the physical fl ow features in this type of geometries.
Author:
M. Belharizi, A. Khorsi, Tayeb Yahiaoui, O. Ladjedel, L. Adjlout,c F. Zemani, O. Sikula
Keywords:
heat transfer, natural convection, diff erentially heated cavity, RANS, LES
Page:
1017
PHYSICAL PROPERTIES OF NANOCONCRETE
Studies have been carried out aimed at improving the corrosion resistance of concrete and its other characteristics
for operation in harsh environmental conditions. The infl uence of a complex additive containing multilayer carbon
nanotubes and hydrothermal SiO2 nanoparticles on the durability of concrete has been determined. Experiments
were carried out to study water tightness, frost resistance, water absorption, and power parameters of concrete
(stress intensity factors). It has been established that the introduction of nanoparticles into concrete improves the
microstructure of its cement matrix, which leads to a decrease in the penetration of chloride ions into concrete and
to an increase in its water permeability.
Author:
E. N. Polonina, S. N. Leonovich, S. A. Zhdanok, V. V. Potapov, T. N. Sedlyar
Keywords:
concrete, nanosilica, nanocarbon, permeability, frost resistance, corrosion
Page:
1028
ABOUT ONE MECHANISM OF CONTROLLING THE MOVEMENT OF MAGNETIC PARTICLES BY A MAGNETIC FIELD IN A NONUNIFORMLY HEATED LIQUID
A model of the transport of magnetic particles by a uniform magnetic fi eld in a nonuniformly heated nonmagnetic
liquid is proposed. The mechanism of transfer is based on taking into account the collective perturbation of the
distribution of temperature and of the magnetic fi eld strength by nonuniformly heated particles in the surrounding
liquid. The change in the magnetic permeability of particles with temperature is taken into account. The interaction
of particles leads to the appearance of a thermomagnetic force acting on particles in an external uniform magnetic
fi eld. The direction of movement of particles under the action of such a force depends on the mutual orientation of
the vectors of the magnetic fi eld strength and temperature gradient and can be either in the direction of an increasing
or a decreasing temperature. The speed and magnitude of particle displacement in these cases are diff erent, which
means the anisotropy of the thermomagnetophoresis coeffi cient. The results obtained agree with the experimental
data.
Author:
S. I. Martynov
Keywords:
viscous fl uid, magnetic nanoparticles, magnetic fi eld, temperature gradient, interaction of particles, anisotropy of transport coeffi cient
Page:
1037
ANALYSIS OF THE CONCENTRATION POLARIZATION OF TECHNOLOGICAL SOLUTIONS IN THE PROCESS OF THEIR NANOFILTRATIONAL SEPARATION
A method of determining the nonstationary concentration polarization of a solution, fl owing in a plane channel, in the process of nanofi ltration of the solution fl ow is proposed. The concentration polarization of the aqueous solutions, containing 0.5 kg/m3 of ZnSO4 and SnSO4, in the process of their nanofi ltrational separation was analyzed. It was established that an increase in the transmembrane pressure in a separation apparatus in the range Pm = 0.5–2.0 MPa causes the coeffi cient of concentration polarization of the ZnSO4 and SnSO4 solutions in this apparatus to increase in the ranges θ = 1.340–1.436 and θ = 1.351–1.430, respectively. A calculation of the time of work of a membrane in a stationary regime and the volume of the permeate obtained in it has shown that, before a membrane is regenerated, the nanofi ltrational separation of ZnSO4 and SnSO4 from their solutions at a defi nite
pressure can be conducted for the times tm = 2070–2791 s and tm = 2893–2036 s, respectively. An increase in
the transmembrane pressure causes these times to decrease and the amounts of the permeates obtained for the
stationary-regime time to increase from 0.200 to 0.266 dm3
and from 0.202 to 0.262 dm3
, respectively.
Author:
S. I. Lazarev, K. V. Shestakov, S. I. Kotenev, N. N. Ignatov
Keywords:
nanofi ltration, membrane, separation, concentration polarization, heavy metal ions
Page:
1045
EQUATIONS OF STATE FOR CALCULATING THE PRESSURES OF SHOCK-WAVE COMPRESSION OF PENTAERYTHRITOL TETRANITRATE (PETN)
An approach is proposed making it possible to construct the shock adiabats of molecular crystals of nitro
compounds based on the data on their isothermal compression. For this purpose, an equation of state for a crystal of
pentaerythritol tetranitrate (PETN) was constructed. The employed comparative analysis of the experimental data
on the shock-wave compression of a simple PETN crystal with calculations carried out using the proposed approach
to converting the isothermal compression pressures to the shock adiabat and the constructed equation of state of the
PETN showed that the experimental and calculated pressure values are within the experimental error.
Author:
Yu. M. Kovalev, E. V. Pomykalov
Keywords:
equation of state, molecular crystal, isothermal compression, Helmholtz energy, Debye approximation, shock adiabat, Grüneisen coeffi cient
Page:
1052
WATER VAPOR ISOTHERM AS A FUNCTION OF THE ACCURACY OF DETERMINATION OF AN ADJUSTABLE PARAMETER
A calculation is presented for isotherms of an equation of water vapor state in the temperature range
T = 773–1473 K on the basis of a fractal state equation and the Fract EOS software module. Good agreement has
been obtained between the calculation results and experimental data
Author:
R. A. Magomedov, É. N. Akhmedov
Keywords:
equation of state, fractional-order integration-diff erentiation, Helmholtz potential, water vapor, isotherm, thermophysical properties
Page:
1060
NUMERICAL SOLUTION OF INVERSE PROBLEMS IN FILTRATION OF A VISCOPLASTIC FLUID
According to the data obtained in laboratory rheological studies, oils from some fi elds are the Bingham nonNewtonian fl uids. In this work, inverse problems are solved numerically to determine the fi ltration parameters of the
reservoir. The curves showing the change in pressure and temperature are used as the initial information. The results
of the interpretation of real curves obtained from a model with a limiting gradient and from a model with a piecewise
linear fi ltration law are compared.
Author:
M. Kh. Khairullin, E. R. Badertdinova, R. M. Khairullinb
Keywords:
Bingham non-Newtonian fl uid, limiting pressure gradient, vertical well, regularization, hydrodynamic studies, thermohydrodynamic studies, numerical simulation
Page:
1066
PERFORMANCE OF A TANK FILLED WITH DESUBLIMATED URANIUM HEXAFLUORIDE AS A FUNCTION OF THE CONFIGURATION OF CENTRAL OPENINGS IN ITS RIBS
Numerical simulation has been performed for an unsteady-state process of uranium hexafl uoride desublimation in a
vertical submersible tank with a volume of 6.0·10–2
m3
as a function of the confi guration of central openings in the
horizontal ribs set up in the tank. It has been established that the tank has a minimum fi lling time and a maximum
average performance equal to 4.8328 g/s at a diameter of the central opening of the 1st rib of 6.4·10–2 m and a
diameter of the central opening of 4.4·10–2 m in the ribs from the 2nd to the 13th.
Author:
A. A. Orlov, R. V. Malyugin, I. A. Turbina
Keywords:
uranium hexafl uoride, desublimation, mathematical modeling, heat and mass transfer processes
Page:
1072
MODELING OF COOLING TOWER OPERATION WITH CONSIDERATION FOR THE CHEMICAL WORK IN THE STEAM–AIR MIXTURE
A model of motion of a two-phase continuous medium in a cooling tower is presented. The medium consists of
water particles and a steam/air mixture. The composition of the mixture changes, as a result of which chemical
work is performed, which was not taken into account in early models. Comparison with earlier results reveals a
strong infl uence of the chemical work on the results of modeling, with the general mathematical structure of the
model remaining unchanged — in the case of free convection, it is necessary to solve an eigenvalue boundary-value
problem with a continuous spectrum, where the eigenvalue is the air fl ow at the cooling tower inlet, and the minimum
fl ow value corresponds to free convection
Author:
K. O. Sabdenov, T. M. Zhakupov, M. Erzada
Keywords:
cooling tower, optimal sizes of water droplets, droplet and stream entrainment, chemical work, mathematical simulation
Page:
1081
FREE CONVECTION HEAT TRANSFER ON ANNULAR-FINNED TUBES AND BUNDLES THEREOF
The use of air-cooled heat exchangers in various industries has increasingly become wide-spread due to their
environmental friendliness and the absence of the need for cooling water. Air-cooled heat exchangers made of
annular-fi nned tubes are widely used in chemical, petrochemical, oil-refi ning, gas, and food industries, and also
at automobile CNG fi lling stations, in heat power and electric power engineering, refrigeration technology, and at
nuclear power plants.
The heat power of air-cooled heat exchangers is largely determined by the characteristics of the motion of
the fl ow of cooling air through it, which can be organized with consumption of electric power by means of a ventilator
or in an energy-saving regime, i.e., by free convection. Unfortunately, the region of ambient air temperatures, at
which it is possible to use air-cooled heat exchangers under the conditions of free convection, is limited. Low
intensity of heat transfer compared to forced convection is the main disadvantage of a free convective regime, which
is usually compensated by an increase in the heat-transfer area, namely, by fi nning the heat-transfer area. In the case
of equipping air-cooled heat exchangers with additional devices that make it possible to intensify free convection the
heating capacity of a heat exchanger can be signifi cantly increased.
The paper presents a review of experimental and numerical investigations of free convection heat transfer
on air-cooled annular-fi nned tubes and bundles thereof
Author:
G. S. Marshalova, A. B. Sukhotskii, V. B. Kuntysh
Keywords:
free convection, bimetal annular-fi nned tube, heat-transfer bundle, Nusselt number, Grashof number, Rayleigh number, air-cooled device
Page:
1089
DISTURBANCES IN A GENERALIZED THERMOELASTIC HALF-SPACE WITH VOIDS AND MICROTEMPERATURES DUE TO A MECHANICAL FORCE
The two-dimensional deformation of a generalized thermoelastic half-space with voids and microtemperatures under
the action of a mechanical force was investigated. The eff ect of the voids and microtemperatures in this half-space
on the displacements, the stresses, the temperature distribution, the change in the volume fraction fi eld, and the fi rst
heat fl ux momentum in it was determined on the basis of the normal-mode analysis with the use of the Lord–Shulman
and Green–Lindsay theories for an insulated boundary.
Author:
L. Rani
Keywords:
thermoelasticity, voids, normal mode, microtemperature
Page:
1103