Volume 94, №5
SYNTHESIS OF JET SYSTEMS FOR COOLING OF COMPUTING DEVICES
The structure of systems for the jet cooling of computing devices with a heat transfer of Newtonian kinetics was
analyzed, and an algorithm was proposed for the synthesis of such systems by the criterion of minimum of their
overall heat transfer coeffi cient. It is shown that the optimum order of contact interaction of a cooling agent with
computing devices cooled in a system is independent of the power of each of the devices, and is dependent only on
their temperature. Relations have been derived for calculating the overall heat transfer coeffi cient of a system for the
cooling of computing devices and the heat transfer coeffi cients of each of them
Author:
I. A. Sukin, A. M. Tsirlin, and A. A. Demidov
Keywords:
cooling jet system, heat transfer coeffi cient, optimum structure
Page:
1093
CONTROLLING THE POWER OF THE INTERNAL HEAT SOURCES OF SPACE VEHICLES
This article briefl y considers the basic principles of the modern digital systems of controlling space vehicles and the
methods of their provision in solving the thermal control problems. For the generalized model of heat exchange with
lumped parameters, the problem of nonterminal control of the heat power of internal sources has been formulated
and solved by the variational-iterative method. The developed procedure has been verifi ed using the simplest model
of heat transfer in a nonhermetic space vehicle
Author:
A. G. Vikulov and A. V. Morzhukhina
Keywords:
automatic control, heat exchange, inverse problems, regularization, variational method
Page:
1101
METHODOLOGY OF SOLVING INVERSE HEAT CONDUCTION AND THERMOELASTICITY PROBLEMS FOR IDENTIFICATION OF THERMAL PROCESSES
An approach to solving the inverse problem of thermoelasticity that employs A. N. Tikhonov′s regularization
principle and the method of infl uence functions has been suggested. The use of A. N. Tikhonov′s regularization with
an effi cient algorithm of the search for the regularization parameter makes it possible to obtain a stable solution of
the inverse problem of thermoelasticity. The unknown functions of displacement and temperature are approximated
by the Schoenberg splines, whereas the unknown coeffi cients of these functions are calculated by solving the system
of linear algebraic equations. This system results from the necessary condition of the functional minimum based on
the principle of least squares of the deviation of the calculated stress from the stress obtained experimentally. To
regularize the solutions of the inverse heat conduction problems, this functional also employs a stabilizing functional
with the regularization parameter as a multiplicative multiplier. The search for the regularization parameter is
effected with the aid of an algorithm analogous to the algorithm of the search for the root of a nonlinear equation,
whereas the use of the infl uence functions makes it possible to represent temperature stresses and temperature as a
function of one and the same sought vector. This article presents numerical results on temperature identifi cation by
thermal stresses measured with an error characterized by a random quantity distributed by the normal law
Author:
Yu. M. Matsevityi, E. A. Strel′nikova, V. O. Povgorodnii, N. A. Safonov, V. V. Ganchin
Keywords:
inverse problem, thermal stress, infl uence function, spline, identifi cation, regularization, functional
Page:
1110
VARIATIONAL METHODS OF SOLVING PROBLEMS ON CONTROL OF THE INTENSITY OF A TEMPERATURE FIELD
The possibility of effective application of variational methods to the solution of problems on optimum control of
decrease in the intensity of the temperature perturbations of the surroundings of devices, attained with the use
of heterogeneous laminated composition coatings, was investigated. In the process of investigating the conditions
of optimum control of the intensity of a temperature fi eld with the use of a heterogeneous laminated composition
construction, qualitative relations between the parameters of such a construction, which allows one to estimate its
effi ciency and potentials, have been obtained
Author:
E. L. Guseva, V. N. Bakulin
Keywords:
variational methods, optimum control, Pontryagin maximum principle, heterogeneous laminated heatresistant construction, constructive analysis, temperature action, optimization criterion, global minimum of a functional
Page:
1117
CONDITIONS AND CHARACTERISTICS OF THE PROCESSES OF HEAT TRANSFER IN JUNCTIONS OF THERMOELECTRIC TRANSDUCERS
Models of heat transfer in sensing elements of thermoelectric transducers have been given, which describe the
heating of such a transducer in the process of its operation with account taken of the structure of the transducer, the
auxiliary reinforcement, and temperature-measurement conditions. Necessary durations of warmup of the sensing
elements of thermoelectric transducers, which characterize their thermal inertia, have been determined depending
on the rate of their heating and the conditions of contact with the working medium with account of the infl uence of
incomplete thermal contact, the presence of a protection sleeve, the structure of a sensing element, and the property
of materials used to fi ll the sleeve on the integral characteristics of the process of measuring. The presented results
may be used for tuning temperature monitoring and control systems and correcting the conditions of installation of
thermoelectric transducers, and also for predictive calculations of the measurement error under specifi ed conditions.
Author:
Yu. K. Atroshenko, O. S. Yashutina
Keywords:
temperature measurement, thermoelectric transducer, error, inertia, heat transfer, mathematical modeling
Page:
1124
SENSITIVITY ANALYSIS OF THE FILM-COOLING EFFECTIVENESS OF AN UPSTREAM CRESCENT-SHAPED VORTEX GENERATOR TO GEOMETRIC PARAMETERS
This study numerically investigates the fl ow fi eld and cooling effectiveness of a cylindrical fl at-plate fi lm-cooling
hole with an upstream crescent-shaped vortex generator (CSVG) at the blowing ratio 0.5 and 1.5. With the aid of a
new antikidney-shaped vortex pair, this CSVG can markedly improve the cooling effectiveness in comparison to a
cylindrical hole. The effects of fi ve geometric parameters completely depicting the CSVG shape are investigated by
a four-level and fi ve-parameter Taguchi approach. It is shown that the ranking order of each geometric parameter is
improved at both blowing ratios. The preliminary recommended upstream CSVGs with higher area-averaged cooling
effectiveness are given for both used ratios
Author:
C. Zhang, L. C. Bai, P. F. Zhang
Keywords:
fi lm cooling, cylindrical hole, antikidney-shaped vortex pair, cooling effectiveness, Taguchi approach
Page:
1137
MATHEMATICAL DEFINITION OF THE TRANSITION BOUNDARIES BETWEEN COLLISION REGIMES OF DROPLETS
Experimental investigations have been performed in an effort to obtain a general approximate expression for the
defi nition of the transition boundaries between the four collision regimes of droplets (their rebound, dispersion,
coagulation, and fragmentation) depending on the key parameters of the interaction of the droplets (their Weber
number, the dimensionless linear collision parameter of the droplets, and the ratio between their sizes). Water was
used as a base liquid. An information background of values of the indicated parameters has been created for the
purpose of their use in the prediction of the critical Weber number of droplets experiencing transitions between the
four collision regimes
Author:
G. V. Kuznetsov, Ya. Solomatin, P. A. Strizhak, N. E. Shlegel
Keywords:
liquid droplets, collisions, regime maps, transition boundaries, general approximate expression
Page:
1147
ON THE THEORY OF ACOUSTIC SOUNDING OF HYDRAULIC-FRACTURING CRACKS PERPENDICULAR TO THE WELL
Consideration has been given to the possibility of investigating the reservoir properties of hydraulic-fracturing
cracks using an acoustic "television receiver," which represents a cylindrical probe with a length of several meters
and is equipped with a pulsed-signal generator and pressure transducers. It is assumed that the pulsed signal is
produced in the liquid in the gap between the probe casing and the open well wall. The evolution of the signal,
which is recorded by the pressure transducers in the form of the attenuation of its amplitude and the appearance of
refl ected pressure surges, permits assessing the state of the face zone, and also the presence and quality of hydraulicfracturing cracks. It is agreed that the cracks initiated by hydraulic fracturing are perpendicular to the well. The well
and the formation around it are fi lled with one and the same acoustically compressible liquid. A mathematical model
has been adopted according to which the wavelength of the acoustic signal is smaller than the length of the probe
but is larger than the size of the gap between the probe casing and the well. Furthermore, during the propagation of
the wave in the gap, the infl uence of viscosity is manifested in a thin boundary layer near gap walls. The width of the
hydraulic-fracturing crack is much smaller than the wavelength. Therefore, it is considered as a refl ecting surface.
On the basis of this model, dispersion expressions have been obtained for the phase velocity and the attenuation
coeffi cient when the signal propagates in the gap, and also for the coeffi cient of refl ection and transmission by the
refl ecting surface. The problem is solved numerically by the method of fast Fourier transformation. An analysis has
been made of the infl uence of fi ltration characteristics of the cracks and the formation, and also the size of the gap
on the evolution of harmonic waves and pulsed signals in the gap between the probe casing and the well wall
Author:
V. Sh. Shagapov, É. V. Galiakbarovaa, Z. R. Khakimova
Keywords:
well, probe, crack, hydraulic fracturing of the formation, harmonic pressure waves
Page:
1160
DISTRIBUTION OF THE DENSITY OF HEAT SOURCES ORIGINATING IN AN OIL-SATURATED BED ON ABSORPTION OF HIGH-FREQUENCY ACOUSTIC AND ELECTROMAGNETIC WAVES
A method of heating an oil bed by means of the energy of electromagnetic and acoustic fi elds introduced into an
oil-saturated bed is investigated. Different variants are considered: electromagnetic heating alone, acoustic heating
alone, joint heating of the bed by both radiators located on the well within the power of the oil bed. As a result of the
dissipation of the energy of the waves, volumetric heat sources appear in the medium the magnitude of which can be
calculated by the Umov–Pointing theorem. The densities of the heat sources originating in the bed on propagation
of acoustic waves at different frequencies (6, 16, and 22 kHz, with the frequency of electromagnetic waves
13.56 MHz) are compared. This article uses an exact expression for calculating the volume density of heat sources
from acoustic waves, and simplifi ed formulas are given for the far-lying and close-lying radiation zones. The character
of distribution of the density of heat sources in the bed at different distances from the radiators is investigated.
Author:
G. R. Izmailovaa, L. A. Kovaleva
Keywords:
hardly extracted reserves, high-frequency electromagnetic fi eld, acoustic fi eld, volume heat sources, oil saturated bed, Hankel function
Page:
1170
ON PRESSURE WAVE IMPACT ON A SOLID WALL COVERED WITH A BUBBLE SCREEN OF FINITE DIMENSIONS
Investigation results are presented on the study of the impact of a "step"-type pressure wave on a solid wall covered
with a bubble screen of fi nite dimensions. Due to the fi niteness of the bubble screen dimensions, account is taken of
two-dimensional effects.
Author:
I. K. Gimaltdinov, A. A. Gimaltdinova, E. Yu. Kochanova
Keywords:
pressure wave, bubble screen, pressure amplitude, focusing, two-dimensionality
Page:
1178
CALCULATING THE THERMOHYDRAULIC EFFICIENCY OF POROUS STEAM-GENERATING CHANNELS IN THE TRANSITION REGION OF MOTION OF A FREON 12 HEAT-TRANSFER AGENT WITH BOUNDARY CONDITIONS OF THE FIRST KIND
The author has presented results of calculating the effi ciency of porous channels during the evaporation of a vapor–
liquid Freon fl ow in the transition region of motion of the heat-transfer agent and with boundary conditions of the
fi rst kind. For the sake of comparison, use was made of a smooth-wall tube as the reference surface. As a result of the
conducted investigations, it has been shown that with the Freon 12 heat-transfer agent, positive values of geometric
and energy coeffi cients of effi ciency can be obtained. The dependences of the effi ciency coeffi cients on the basic
operating-structural parameters of the model have been analyzed
Author:
A. P. Lukisha
Keywords:
thermohydraulic effi ciency, porous steam-generating channels, transition region of motion of the heattransfer agent, boundary conditions of the fi rst kind, Freon 12 heat-transfer agent
Page:
1185
EVAPORATIVE COOLING OF A SUBSTRATE BY A PULSE-PERIODIC SPRAY WITH FEMTOLITER DROPLETS
Dissipative energy fl uxes in evaporative cooling of a substrate by droplets carried in by an air fl ow have been measured.
It has been shown that the frequency of feeding the spray and the difference between its temperature and the temperature
of the substrate infl uence the effi ciency of its cooling. Spraying pulses with a relative duration of 0.5 and 0.25 have
been investigated. It has been found that the form of these pulses does not infl uence, in practice, the intensity of cooling
of the substrate at spray-feed frequencies higher than 3 Hz. It has been confi rmed that the thermal conductivity and
thickness of the substrate substantially infl uence the value of the energy fl ux dissipated by it.
Author:
V. I. Saverchenko, S. P. Fisenko
Keywords:
relative pulse duration, thermal conductivity of the substrate, substrate temperature, dissipative flux
Page:
1227
ACCOUNT FOR THE PROCESS OF UNDERGROUND CONDENSATION IN MODELING HEAT AND MOISTURE EXCHANGE IN FROZEN SOILS
A mathematical model of heat and moisture transfer with account for condensation and evaporation of underground
moisture during seasonal thawing of permafrost is considered. The motion of moisture can be described with the aid
of transfer equations in its moisture content-governing or potential forms in saturated and nonsaturated soils. Based
on experimental and full-scale data, verifi cation of the parameters of underground condensation and evaporation of
the pore moisture has been made. Numerical realization of the set nonlinear problem of heat and moisture transfer
is made by the fi nite-difference method with the use of the Newton method. The adequacy of the proposed model
of seasonal thawing of perennially frozen soils is shown. As a result of numerical experiment under the conditions
of Central Yakutia, it has been established that with account for the condensation of underground moisture the
overall moisture content of the soil increases. In the spring–summer period, an intense process of evaporation of
the underground moisture and lowering of the temperature are observed, while in the summer–autumn period, an
increase in the heat content of the soil is observed with increase in the quantity of condensate fallout. At the end of
the summer season, in September and at the beginning of October, the choking of the moist thawed layer occurs. The
proposed mathematical model with account for the process of underground condensation more adequately refl ects
the process of freezing of the zone of "choking." These results are indicative of the adequacy of the improved model
and of the possibilities of using it for predictions
Author:
P. P. Permyakov, A. F. Zhirkov, M. N. Zheleznyak
Keywords:
heat and moisture transfer model, permafrost, heat- and moisture transfer regime of soils, underground condensation, active layer
Page:
1232
IMPACT OF A 3D PLATE ON THE STRUCTURE OF A TURBULENT BOUNDARY LAYER
The authors have performed 3D numerical investigations into the velocity fi eld behind a 3D thin plate by the LES
method. The plate was located at a height of 0.002 m in a turbulent boundary layer formed in a water channel. The
chord length of the plate and its spanwise size were equal to 0.01 m and 0.024 m respectively. The Reynolds number
calculated from the half-width of the channel and the velocity on its axis was equal to 7500. It has been shown that
under the impact of the wake of the plate, the longitudinal velocity normalized to the stagnation velocity grew in the
logarithmic region at a distance to x/δ = 3.8, and pulsations of all the velocity components decreased in the buffer
region to the distance x/δ = 0.8. As the lower shear layer of the wake approached the surface, longitudinal pulsations
reached their minima at the wall at x/δ = 1.8, whereas vertical and transverse pulsations became higher than those
in an unperturbed boundary layer. The calculated characteristics of the velocity fi eld satisfactorily correlated with
the relevant characteristics obtained in experimental investigation with similar initial and boundary conditions. An
analysis of the velocity fi eld has revealed the mechanism of impact of the wake on the structural change of wall fl ow.
The involvement of the wall medium in the lower shear layer generated the outfl ow of the medium from the channel
wall, and the involvement in the upper shear layer formed the infl ow of a high-speed medium to the buffer region.
The medium′s outfl ow from the wall led to a reduction in the velocity gradient at the surface. Shear stresses decreased
at a distance of four thicknesses of the boundary layer, and their local reduction amounted to as much as ~30%.
Trailing vortices descending from the plate′s side edges created a nonuniform transverse-velocity distribution. This
nonuniformity caused the vorticity to form in the buffer region. The arising system of small-size vortices blocked the
feed of the high-speed medium to the wall, retarding the growth in the shear stresses on the surface in the interval
1.4 ≤ x/δ ≤ 2.6. The vortex system degenerated upon the stabilization of the transverse velocity and shear fl ow on the
surface was restored.
Author:
V. L. Zhdanov, D. A. Ivanov, I. G. Kukharchuk
Keywords:
turbulent boundary layer, velocity fi eld, shear stresses, vortex generator, LES, PIV
Page:
1242
INVESTIGATION OF THE STRUCTURE AND CHARACTERISTICS OF A NONSTATIONARY SUPERSONIC GAS JET PRODUCED BY A PULSE GENERATOR
The initiation of a shock wave in the gas space of a pulse generator, the exit of this wave from the generator
nozzle, and the formation of a nonstationary gas-jet fl ow downstream of the nozzle exit section were experimentally
investigated and numerically simulated as applied to the installations for the gas-pulse cleaning of heat transfer
surfaces. An experimental investigation of the structure of a nonstationary underexpanded supersonic gas jet
discharging from the generator nozzle into an immersed space and propagating along a side screen modeling a heat
transfer surface cleaned was performed on an air stand. The shock-wave and vortex structures of such a jet were
numerically investigated in detail by the method used for the simulation of large vortices.
Author:
K. N. Volkov, V. N. Emel′yanov, A. V. Efremov, A. I. Tsvetkov, P. S. Chernyshov
Keywords:
gas-pulse cleaning, pulse generator, shock wave, supersonic underexpanded jet, vortex-resolving simulation
Page:
1255
DEVELOPING PULSATING SMALL-AMPLITUDE LAMINAR FLOW IN A RECTANGULAR CHANNEL
The method of numerical simulation of the hydrodynamics of a developing steady-state pulsating small-amplitude
laminar fl ow of an incompressible Newtonian liquid in a rectangular microchannel is presented based on the
boundary-layer theory. The simulation was carried out for fl ow with Re = 100–2000. Distributions of the coeffi cients
of hydraulic resistance and of skin friction of fl ow along the channel length are obtained. Conclusions are drawn on
the length of the initial hydrodynamic segment and on the changes in the amplitude and phase of vibrations of the
hydraulic resistance and skin friction coeffi cients and of longitudinal velocity. The distribution of the shear stress, as
well as of its amplitude and phase over the channel perimeter, has been determined.
Author:
M. S. Purdin
Keywords:
hydrodynamics, pulsations, rectangular channel, developing laminar fl ow
Page:
1266
ANALYSIS OF THE LOADING CONDITIONS FOR A GUN-START OF A GROUP OF SUPERCAVITATING STRIKERS
Analysis has been made of the ballistic characteristics of the shots, and a powder grade has been indentifi ed for a
propellant powder charge ensuring the lowest level of force action on the projectile assembly including a group of
supercavitating strikers in a gun-start.
Author:
V. V. Burkin, A. S. D′yachkovskii, A. N. Ishchenko, V. Z. Kasimov, K. S. Rogaev, A. Yu. Sammel′, N. M. Samorokova, A. D. Sidorov, E. Yu. Stepanov
Keywords:
loading conditions, propellant powder charge, group launching, supercavitating striker, parametric studies, mathematical model
Page:
1278
DETONATION REGIME IN COMBUSTION OF HEPTANE AND JET A-1 PROPELLANT IN A LESS THAN 0.5-m-LONG SMALL-SIZE COMBUSTOR
This paper is devoted to investigating the dynamics of propagation of a combustion wave in a small-size pulse detonation
combustor with a length of less than 0.5 m operating on heptane and Jet A-1 propellant. A link has been established
between the combustion wave propagation velocity and the pulse detonation combustor thrust and the ratio of the
components of a fuel–air–oxygen mixture. The maximum wave velocity and detonation combustor thrust are achieved
irrespective of the type of fuel in mixtures of parastoichiometric composition, with the propellant being inferior to
heptane in terms of both combustion velocity (more than three times) and the developed thrust (almost two times).
Author:
M. S. Assad, O. G. Penyazkov, I. I. Chernukho, Khaled Alhussan
Keywords:
detonation, heptane, propellant, wave velocity, jet thrust, equivalence ratio
Page:
1285
NUMERICAL INVESTIGATION OF THE PROCESS OF PEAT GASIFICATION IN AN OXYGEN-ENRICHED VAPOR–AIR MIXTURE IN A FIXED BED UNDER A PRESSURE OF 1.5 MPa
A two-dimensional system of parabolic and hyperbolic equations has been constructed describing the aerodynamics, heat and mass transfer, and chemical reaction of a gas-dispersion medium in a fi xed bed. An investigation has been made into the effects of particle motion velocity and H2O content in a vapor–air mixture on the temperature and
concentration phase fi elds, unburned carbon loss, grate slagging, steadiness (stabilization) and stationarity of the
gasifi cation process, and the calorifi c value of synthetic gas. An original method has been proposed for the supply of
coal dust into the burners using generator (producer) gas as a working medium ejecting fi ne dust
Author:
B. B. Rokhman
Keywords:
fi xed bed, coal, thermal conductivity, heat transfer, steam–oxygen gasifi cation, conductive and radiative heat transfer, temperature, chemical reactions
Page:
1290
OBTAINING HYDROGEN FLUORIDE DURING THE INTERACTION OF URANIUM HEXAFLUIORIDE WITH HYDROGEN AND OXYGEN IN A COMBUSTION REGIME. EXPERIMENT
In the course of experiments on a pilot plant with a vertical cylindrical reactor of the "tunnel burner" type whose inside diameter is equal to 142 mm, it has been established that when UF6, H2, and O2 with a nearly 1:3:1 molar ratio respectively and a cold-mixture-fl ow Reynolds number of the order of 10,000 are fed to the reactor, a stable fl ame of diffusion combustion is formed. It is initiated by a self-igniting fl uorine-ammonia pair at a fl uorine fl ow rate of the order of 0.5% of the UF6 fl ow rate. The major uranium-bearing product of the fl ame process was a mixture of uranium oxides, mainly UO2 and U3O8, in which fl uorine covalent-bonded to uranium was present in the amount 0.1–3% mainly in the form of UF4 and UO2F2. The major fl uorine-containing product was hydrofl uoric acid with a
content of hydrogen fl uoride higher than 95%. From the data obtained, a technology can be developed for obtaining
anhydrous hydrogen fl uoride from depleted uranium hexafl uoride.
Author:
D. S. Pashkevich, Yu. I. Alekseev, D. A. Mukhortov, P. S. Kambur, V. B. Petrov, D. A. Bazhenov, A. R. Zimin, P. A. Smolkin, V. V. Kapustin
Keywords:
hydrogen fl uoride, depleted uranium hexafl uoride, uranium oxides, combustion
Page:
1304
MODELING THE SYNTHESIS OF BARIUM TITANATE MICRON PARTICLES IN AXISYMMETRIC DIRECT-FLOW AND THREE-ZONE REACTORS
A study is made of heat- and mass-transfer regime in a porous medium consisting of gas and solid reactants and
products of synthesis of micron particles during the motion of a combustion front in cylindrical channels with
account of thermal and mass dispersions. A model of a three-zone reactor is proposed, and a comparative analysis
is made of the infl uence of dispersion on the process of operation of fl ow and three-zone reactors. Modeling results
for different geometric parameters of the synthesis reactors are compared. A comparison is made of the results of
calculating the synthesis of barium titanate and calculating for the model without thermal dispersion. Advantages
of the three-zone reactor are noted
Author:
A. V. Markov
Keywords:
synthesis of oxides during the combustion of carbon, three-zone and direct-fl ow reactors, superheating phenomenon, two-temperature model, dispersion
Page:
1312
VISCOUS PROPERTIES OF PETROLEUM-CONTAINING WASTE WATERS FROM INDUSTRIAL ENTERPRISES
Investigations on estimating the rheological properties of waste water containing various quantities of petroleum
products have been conducted. The dependences of the density and dynamic viscosity of water–petroleum emulsions
on the content of petroleum products in them have been studied. Kerosene and motor oil have been selected as
petroleum products. To compare the results of calculations of the viscosity of water–petroleum emulsions with
corresponding experimental data, simulation of the properties of the indicated emulsions has been made with the use
of various correlations and of Einstein's and Safarov's equations
Author:
E. S. Dremicheva, A. G. Laptev
Keywords:
petroleum-containing waste waters, water–petroleum emulsions, density, dynamic viscosity
Page:
1326
REGULARITIES OF NONISOTHERMAL CRYSTALLIZATION IN THE FORMATION OF A PLANE VISCOELASTIC FILM
A study is made of the processes of heat transfer and nonisothermal crystallization during the formation of a plane
viscoelastic polymer fi lm with the upper-convected Maxwell model, in which the thermophysical properties, viscosity,
and relaxation time of the polymer depend on its temperature and the degree of crystallinity. The mathematical model
is supplemented with the equation of nonoisthermal-crystallization kinetics. The problem is solved by the fi nite
difference method
Author:
A. V. Baranov
Keywords:
viscoelastic liquid, heat transfer, plane polymer fi lm, crystallization
Page:
1331
MATHEMATICAL SIMULATION OF A HIGH-FREQUENCY LOW-PRESSURE DISCHARGE WITH GAS INJECTION IN NON-LOCAL APPROXIMATION: ELECTRO- AND PLASMADYNAMICS
The electro- and plasmadynamic parameters of a high-frequency discharge at a low pressure (13.3–200 Pa) with a
gas blowing-through are investigated in a nonlocal approximation. A discharge in a cylindrical discharge tube in a
medium of argon is considered. The fl ow at the beginning of the discharge tube occurs in the regime of a continuous
medium, whereas in the region of a plasma bunch and further downstream the fl ow regime changes to a freemolecular one. In this connection, a hybrid mathematical model is constructed that includes the Boltzmann equation
for a neutral gas and the balance equations of the concentration and energy of electrons in the continuous medium
approximation. The equations for the plasma particles are supplemented by the Maxwell equations transformed
into the equations of telegraphy in the high-frequency electric intensity. The results of calculations of the electric
intensity, concentration of electrons, and of electron temperature in the discharge tube are presented. It is shown
that account for the nonlocality is an essential factor in simulating the high-frequency inductive discharge with gas
injection ensuring effective transfer of charged particles from the fi eld of their generation to the working chamber.
Author:
A. Yu. Shemakhin, V. S. Zheltukhin, E. Yu. Shemakhin
Keywords:
high-frequency inductive discharge, low pressure, mathematical model
Page:
1336
PLASMA CHEMICAL CONVERSION OF SPENT LUBRICATING MATERIALS
A thermodynamic analysis has been performed using a universal TERRA program. The analysis has made it possible
to identify the optimum parameters of the process of plasma chemical conversion of spent lubricants for various
gasifying agents (air and water vapor). Based on the calculations, a closed-cycle scheme has been proposed for their
integrated plasma chemical treatment, the scheme being a wasteless method of waste conversion. This method makes
it possible to simultaneously obtain synthesis gas suitable for the production of methanol and electricity and isolate
precious nonferrous and rare metals with minimal environment impact
Author:
V. E. Messerle, A. L. Mossé, G. Paskalov, Zh. Zh. Sitdikov, A. B. Ustimenko
Keywords:
plasma chemical processing (conversion), spent lubricants, synthesis gas, precious metals, ecologicaland-economic indicators
Page:
1344
GENERATION OF AN ELECTRON BEAM BY A FOREVACUUM PLASMA SOURCE WITH A SINGLE EMISSION CHANNEL IN THE PRESENCE OF MAGNETIC FIELD
Consideration has been given to the effects of a longitudinal magnetic fi eld in the discharge-emission system of
a forevacuum plasma electron source on the conditions of generating a focused electron beam with high specifi c
power. It has been shown that the creation of a magnetic fi eld with an induction of up to 0.4 mT ensures the possibility
of expanding the emission channel, and, accordingly, increasing the current and current density of the electron beam
while retaining the electric strength of the accelerating gap. As a result, the power density of the electron beam of the
forevacuum plasma electron source has been raised to the value q = 1.5·106
W/cm
2
.
Author:
I. Yu. Bakeev, A. A. Zenin, A. S. Klimov, E. M. Oks
Keywords:
electron beam, plasma electron source, emission channel, magnetic focusing, longitudinal magnetic fi eld, forevacuum pressure region
Page:
1357
MODELING THERMOPHYSICAL CHARACTERISTICS OF NICKEL-BASED SUPERALLOYS
Thermodynamic processes of phase separation having a substantial effect on the temperature characteristics of nickel superalloys have been modeled. Using an empirical approach, new ratios of the elements Kγ′ and Kγ have been obtained for the fi rst time, accounting for the mutual infl uence of the alloying elements on the temperature of multicomponent compositions of cast superalloys. It has been established that with increase in the ratio Kγ′ there
is a rise in critical temperatures and hence, in the thermal stability of the entire system. The calculated values of
critical temperatures for ZhS3LS-M and ZMI-3U alloys are in good agreement with experimental ones. Plots have
been constructed for the ratio Kγ as a function of the alloying system, and an investigation has been made into the
effects of alloying on the liquidus temperature of alloys. Alloying element content ratios are given, as are regression
models using which it is possible to predict the width of the temperature interval of crystallization and the optimal
temperature of homogenization for a specifi c alloy
Author:
A. A. Glotka, S. V. Haiduk, V. Yu. Ol′shanetskii
Keywords:
cast nickel superalloys, thermodynamic processes of phase separation, critical temperatures
Page:
1363
INFLUENCE OF THE TEMPERATURE AND CYCLIC DEFORMATIONS OF (BixSb1–x)2Te3 FILMS ON THEIR RESISTANCE
Results of investigations on the infl uence of the temperature and cyclic alternating mechanical deformations of (BixSb1–x)2Te3 fi lms on their resistance are presented. The mechanism of electrical conductivity of these fi lms is
analyzed.
Author:
Kh. S. Daliev, M. M. Ahmedov, M. K. Onarkulov
Keywords:
substrate, condensation, strain gauge, tensosensitivity, deformation, polycrystal, dislocations
Page:
1369
NANOINDENTATION METHOD FOR STUDYING THE STRUCTURE OF MODIFIED CEMENT STONE
Preliminary results for the cement specimens under study have been obtained by the nanoindentation method. It has been found that the elastic modulus increases in the specimens that contain a complex admixture with nanosize particles. Also, the effect is observed on adding an admixture containing only one type of nanoparticles (sol of nanosilica SiO2 or the MWCNT carbon material). Parameters of the nanoindentation method have been selected that ensure obtaining fi nal consistent results. These results are presented by the histograms of distribution of nanoindentation points by elastic moduli and hardness, and also by the distributions in these characteristics in the horizontal plane xy, which is perpendicular to the nanoindenter′s motion. The obtained results suggest that there is a change in the nanostructure of the C–S–H gel, which is compared with the increment in the strength, the Young moduli, and the shear on adding SiO2 nanoparticles and MWCNT nanoparticles.
Author:
E. N. Polonina, O. Lahayne, J. Eberhardsteiner, V. V. Potapov, S. A. Zhdanok, S. N. Leonovich
Keywords:
complex nanodisperse admixture, nanosilica gel, carbon nanomaterial, nanoindentation, cement specimens, hardness, elastic modulus, nanoindenter, histogram, phase, experimental studies
Page:
1194
RHEOLOGICAL PROPERTIES OF WATER- AND ETHYLENE-GLYCOL-BASED NANOFLUIDS WITH SINGLE-WALLED CARBON NANOTUBES
An experimental study has been made of the viscosity and rheology of water- and ethylene-glycol-based nanofl uids
with single-walled carbon nanotubes, and also of their dependence on temperature. The mass concentration of
the nanotubes ranged from 0.05 to 1%. Polyvinyl pyrrolidone and sodium dodecyl benzenesulfate were used as
dispersants. The dimensions of the single-walled nanotubes were determined by the method of dynamic light
scattering. Preliminary study of the viscosity and rheology of basic fl uids has shown that they are Newtonian fl uids.
However, all the studied fl uids turned out to be pseudoplastic non-Newtonian fl uids. It has been established that with
growth in the concentration of nanotubes in a fl uid, its index decreases, and the consistency parameter increases.
With increase in the temperature of a nanofl uid, its viscosity decreases. The change in the temperature of a nanofl uid
exerts an infl uence on its rheology: the consistency parameter of the nanofl uid increases, and its index decreases,
and this infl uence increases as the concentration of nanotubes in the nanofl uid grows. Ultrasonic treatment of the
nanofl uid leads to a partial degradation of dispersants in it and to an increase in its viscosity. Measures on restoring
the properties of long-stored nanofl uids have been discussed
Author:
V. Ya. Rudyak, D. S. Tret′yakov
Keywords:
nanofl uid, single-walled carbon nanotubes, viscosity, rheology, dispersants
Page:
1208
HEAT PIPES, NANOFLUIDS, AND NANOTECHNOLOGIES
A survey of the constructions of heat pipes and thermosiphons with nanofl uids, nanocoatings, and nanocomposites
based on metal oxides and carbon materials for volume absorption of solar energy and cooling of electronic
components is presented. Nanofl uids are considered as actual working media intended for application in transparent
heat miniexchangers, heat pipes, and thermosiphons for volume heating a nanofl uid by laser or solar radiation.
Nanocoatings of the evaporator walls of heat pipes are created for intensifying two-phase heat transfer in cooling
the devices of high-current electronics. Nanocomposites applied as heat pipe and thermosiphon casings possess
thermophysical and mechanical properties that in a number of cases are best than those from metals.
Author:
L. L. Vasiliev
Keywords:
nanofl uids, nanocoatings, nanocomposites, heat pipe, thermosiphon, evaporator, condenser, cooling system
Page:
1217