Volume 94, №6
INFLUENCE OF ALUMINUM ADMIXTURES ON THE COMBUSTION REGIME OF NANOSTRUCTURED SILICON WITH A SOLID-PHASE OXIDANT
Consideration has been given to the infl uence of additives of aluminum nanoparticles to mixtures of nanostructured
silicon with a solid-phase oxidant on the characteristics of their high-velocity (detonation) combustion.
The thermodynamic characteristics of combustion of the systems "aluminum–silicon–oxygen" and "aluminum–
silicon–ammonium perchlorate," and also the Chapman–Jouguet velocity and the thermodynamic characteristics
of solid-phase mixtures of nanostructured silicon with ammonium perchlorate and aluminum nanoparticles with
a varying content of aluminum oxide have been calculated in a wide range of compositions. It has been established
that for mole fractions of aluminum of less than 0.33 in the solid-fuel mixture, the system has high-velocitycombustion characteristics inherent in silicon-enriched mixtures. It has been shown that detonation combustion of
aluminum–silicon–sodium perchlorate mixtures in this region of concentrations of aluminum occurs with
a signifi cant velocity defect (of 40–50%) with respect to the Chapman–Jouguet detonation velocity
Author:
P. N. Krivosheyev, V. N. Mironov, O. G. Penyazkov, and S. I. Futko
Keywords:
detonation combustion, nanostructured silicon, solid-phase oxidant, gas suspension of particles, aluminum nanoparticles, ammonium and sodium perchlorates, composite fuel, Chapman–Jouguet detonation, mathematical modeling
Page:
1375
SIMULATION OF THE SUPPRESSION OF THE GAS-FREE COMBUSTION OF A CONICAL SAMPLE WITH HEAT REMOVAL
A numerical investigation of the propagation of a combustion wave in a conical sample of a compound in the process of its self-propagating high-temperature synthesis with heat removal from the outer boundaries of the sample has been performed on the basis of the model of the nonstationary gas-free combustion of such a compound in the twodimensional axisymmetric approximation with regard for the heterogeneity of the structure of the compound and the
dependence of the diffusion of the reagents in it on its temperature. The heat removal from the surface of the conical
sample of the compound, critical for the suppression of its combustion, and the dependence of the thickness of the
compound layer burnt out incompletely on the rate of heat removal from the compound and the geometric sizes of
its sample were determined
Author:
A. Yu. Krainov
Keywords:
self-propagating high-temperature synthesis, reaction cells, wave, extinction, mathematical simulation
Page:
1387
INTERACTION OF TYPICAL FIRE-EXTINGUISHING LIQUIDS WITH THE FOREST FUEL COMBUSTION FRONT
The paper presents the results obtained in experimental studies of the processes of localizing the combustion of typical
forest fuel materials (needles, foliage, and their mixtures with twigs) using a control line (fi rebreak) of a wetted layer
of such materials formed before the fronts of their thermal decomposition and combustion. Water, bischofi te solution,
OS–5 solution, bentonite suspension and a foaming agent emulsion were used as fi re-extinguishing agents. Relative
mass and volume concentrations of water impurities were selected in accordance with ranges that are typical of
modern fi re-extinguishing systems. The possibility is shown for localizing the combustion of the said materials by
reducing their temperature through heat accumulation by water, which has a high heat capacity and undergoes
endothermic phase transformations, and blocking the access for the oxidizer and pyrolysis products to the fl ame
combustion zone by forming a buffer zone from relatively cold water vapors and reducing the concentration of the
products of materials' thermal decomposition as a result of the fi re-extinguishing agent spreading on their surface
and pores. The conditions are determined for guaranteed localization of the burning of a forest area by supplying
its control line with a liquid composition in the form of a massive water drop, a jet and aerosol. It is shown that the
supply of an aerosol cloud to the control line is the most effi cient method in terms of minimal liquid consumption and
guaranteed combustion localization
Author:
G. V. Kuznetsov, K. O. Ponomarev, A. V. Zakharevich, and P. A. Strizhak
Keywords:
forest fuel materials, pyrolysis, combustion, control line, fi re-extinguishing agent, emulsion, solution, suspension
Page:
1395
VIBRATING COMBUSTION AS A PROMISING WAY OF REDUCING HARMFUL EMISSIONS INTO THE ATMOSPHERE
The change in the fl ame temperature depending on the modes of combustion of solid biofuel has been investigated.
A decrease in the fl ame temperature, as well as an increase in the heat fl ux density on origination of vibrating
combustion has been revealed. The article presents the results of investigation of the emission of radioactive 137Cs
with fl ue gases at different modes of combustion of solid biofuels contaminated by radionuclides in a wide temperature
range. In the case of vibrating combustion, a decrease in the emission of radioactive 137Cs with fl ue gases is noted. A
theoretical model of the development of sonic perturbations of the combustion wave and of the infl uence of the latter
on heat transfer characteristics has been developed. The results of the studies allow one to develop recommendations
on combustion of a solid biofuel with better ecological characteristics of emissions into the atmosphere and with
improved heat-transfer parameters, which improves the effi ciency of furnace facilities operating on solid biofuel in
heat generators. An empirical-theoretical dependence has been obtained for calculating heat transfer in the Rijke
tube during vibrating combustion. A model of calculation of the perturbation amplitude for instabilities in "vessel–
tube"-type facilities is proposed.
Author:
O. G. Stonik, V. D. Geshele, S. A. Kovalev
Keywords:
vibrating combustion, fl ame temperature, acoustic radiation, harmful ejections, radionuclides
Page:
1400
RESEARCH OF OPERATION OF EQUIPMENT FOR ULTRASONIC PURIFICATION OF EXHAUST GASES OF INTERNAL COMBUSTION ENGINES
This paper is devoted to analytical and experimental modeling of the method of ultrasonic purifi cation of recycled
exhaust gases of internal combustion engines. The scheme of the experimental stand and the procedure for conducting
the experiment are given. The data on determination of the coagulation coeffi cient are presented.
Author:
A. Kadyrov, I. Pak, A. Ganyukov, M. Imanov, and K. Balabekova
Keywords:
ultrasonic purifi cation, coagulation, ultrasonic oscillations, internal combustion engine
Page:
1407
WAVE DYNAMICS OF A VAPOR–DROPLET MIXTURE IN AN ACOUSTICAL RESONATOR
Regimes of longitudinal vibrations of a mixture, consisting of a vapor and a fi ne droplet fraction, in a plane channel
were defi ned with regard for the evaporation of droplets and the condensation of vapor. The regime with complete
evaporation of the droplets and the regime in which the vapor condensates in the process of vibrations of the mixture
with increase in the average density of the dispersed phase were considered. The movement of the carrying medium
was defi ned by the system of equations of motion of a compressible viscous heat-conducting gas with regard for
the exchange of the mass, momentum, and energy between the vapor and the dispersed phase in the mixture, and
the dispersed phase was defi ned by the system of gasdynamic equations with regard for the exchange of the mass,
momentum, and energy between it and the carrying medium. The system of equations defi ning the vapor–droplet
mixture was written in generalized curvilinear coordinates and was solved by the explicit MacCormack method with
splitting of the spatial operator in directions by the scheme of nonlinear correction in each time step.
Author:
A. L. Tukmakov
Keywords:
vapor–droplet mixture, carrying medium, Navier–Stokes equations, explicit MacCormack scheme, equilibrium phase transition, evaporation, condensation
Page:
1415
INVESTIGATION OF RADIATIVE-CONDUCTIVE HEAT TRANSFER BY NONCONTACT MEASUREMENTS. IDENTIFICATION OF MATHEMATICAL MODELS OF HEAT TRANSFER FOR NONTRANSPARENT MATERIALS
Combined theoretical-experimental investigations of the processes of heat transfer in materials of complex structure
are conducted for the case where it is impossible to measure the state of the system at internal points. The problem of
simultaneous determination of the thermal conductivity of a nontransparent material and of the coeffi cient of its heat
exchange with the external medium and with the heat fl ux absorbed by the material has been solved.
Author:
A. V. Nenarokomov and D. S. Semenov
Keywords:
heat transfer model, hyperthermia, biological tissues, inverse heat exchange problem
Page:
1425
MATHEMATICAL MODEL OF INTERRELATED HEAT AND MASS TRANSFER WITH ACCOUNT FOR THE TWO-PHASE LAG
A system of differential equations of interrelated heat and mass transfer under the conditions of nonlocal
equilibrium has been obtained that accounts for the velocities and accelerations of driving forces (of the gradients
of corresponding values and of heat and mass fl uxes caused by them) in the course of the joint occurrence of
nonisothermal diffusion and heat conduction. The system of equations includes second order derivatives with respect
to time and mixed derivatives in the product with corresponding relaxation coeffi cients of interacting fl ows and of
their driving forces (double lag). An analysis of the numerical solution of the resulting system has shown that
the boundary values for the temperature and concentration cannot be adopted instantly, since the process of
determining them takes some time, during which they increase from zero to the values assigned by the boundary
conditions of the boundary-value problem. From comparison of the solutions with and without account for double
lag, it follows that their maximum difference is observed over the initial segment of time, in the course of which
the establishment of boundary conditions and concentrations occurs. Consequently, the solutions of the classical
equations of interrelated heat and mass transfer obtained without taking into account relaxation phenomena within
the range of the time of establishment of boundary conditions cannot be used because of the inadequate description
by them of the real physical processes.
Author:
A. V. Eremin, I. V. Kudinov, V. A. Kudinov, and E. V. Stefanyuk
Keywords:
interrelated heat and mass transfer, relaxation, driving forces, fl ows, double lag, Onsager reciprocal relations, numerical solution, boundary conditions, heat and mass fl uxes
Page:
1432
DISTINCTIVE FEATURES OF HEAT TRANSFER DURING THE COOLING OF THE WORKING SECTION BY A DISPERSED FLOW
The authors have presented results of experimental investigation into the possibility of using dispersed twocomponent fl ows of the coolant to remove heat from the structural elements of thermonuclear facilities and reactors
with a high energy density. Based on the array of experimental data, a criterial equation has been obtained for
the heat transfer from the high-temperature surface to the dispersed two-component coolant. The existence of two
heat-transfer regimes depending on the temperature of the cooled structural element has been established and the
promising nature of this method of recuperation of the energy of structures interacting with high-temperature plasma
has been confi rmed.
Author:
S. V. Mirnov, A. N. Varava, A. V. Vertkov, A. V. Dedov, A. V. Zakharenkov, I. E. Lyublinskii, A. T. Komov, and Yu. V. Smorchkova
Keywords:
diverter, plasma, one-sided heating, dispersed fl ow, cooling, heat transfer, heat-transfer coeffi cient, experimental investigation.
Page:
1438
MOVEMENT OF A MELT AND ELASTIC-STRESSED STATE OF ITS OXIDE FILM IN THE PROCESS OF INDUCTION MELTING
The interdependent movement of a liquid metal and its surface oxide fi lm, found in the state of elastic stress, in the
process of induction melting of the metal in a cylindrical crucible was investigated by the method of direct numerical
simulation. The structures of the liquid fl ows in such a metal, determined for different regimes of its induction
melting, are presented, and an analysis of the state of the surface of the metal melted in these regimes is given. The
equation for the balance of the volume forces in the fi lm covering the whole surface of a molten metal as well as the
equations for the displacements and deformations of this fi lm under certain conditions have been derived. The elastic
properties of an oxide fi lm on the surface of a liquid metal were estimated on the basis of the experimental data on its
induction melting. The interrelation between the liquid fl ow near the surface of a melt and the volume forces in the
fi lm on its surface, the mechanical stress of this fi lm, and its deformations was demonstrated for typical technological
regimes of melting of metals. A computational experiment has shown that the model of the stressed state of a fi lm
on the surface of a melt, developed, is correct and can be used for the defi nition of the elastic stresses in such fi lms.
The infl uence of the diffusion parameter of the magnetic fi eld in a melt and its Hartmann number on the elastic
deformations of the fi lm on the surface of the melt was determined and the relation between these deformations and
the structure of the liquid fl ow at the surface of the melt was investigated.
Author:
I. L. Nikulin, V. A. Demin, and A. V. Perminov
Keywords:
induction melting, molten metal, variable magnetic fi eld, diffusion, heat convection, Lorentz force, oxide fi lm, mechanical stress, elasticity
Page:
1444
SPACE-TIME REGION OF PROPAGATION OF HEAT FLUX THROUGH A LUBRICATED CONTACT WITH ACCOUNT FOR THE HEAT-SHIELDING EFFECT OF OIL FILMS
The investigations deal with the study of the heat-shielding effect of thin oil fi lms during the passage of heat fl ux
through them, the conditions for its occurrence, and the space-time region of propagation through heterogeneous
media with account for the reduced thermophysical characteristics. The paper presents theoretical calculations
and experimental investigations conducted on a special self-engineered device. Consideration has been given to
the infl uence of the oil fi lm thickness, the amplitude and time of the heat pulse on the velocity of its propagation
simultaneously through a lubricated contact and an unlubricated one. The results of observations over the pattern
of heat fl ux propagation has made it possible to draw a conclusion that the heat fl ux released, for example, as a
result of friction on a microscopic contact is characterized by high density and propagates with a signifi cant velocity
predominantly in the direction with the least thermal resistance determined by the thermophysical characteristics
and the temperature potential of the material. Considering that the processes occur at the microscopic level, such
materials include thin boundary fi lms (oil. oxide, spray-applied and other fi lms) with a thickness comparable with
the height of microroughnesses.
Author:
D. A. Popov, A. M. Kadyrmetov, and A. S. Pustovalov
Keywords:
heat fl ux, boundary fi lms, heat-shielding effect, heat fl ux propagation
Page:
1456
IN-LIQUID PLASMA RECYCLING METHOD OF ZINC OXIDE NANOPARTICLES
Zinc nanoparticles applied in the production of zinc–air batteries provide the highest specifi c energy among
various metal–air combinations used in batteries in practice. Recent technical advances provide an opportunity
to successfully solve the problems experienced during the early development of batteries of this type. For example,
there is a major limitation in recharging cycles due to the massive formation of zinc oxide. In the present work, a
reduction process is proposed on the basis of the use of alcohol solvent by applying microwave in-liquid plasma.
The occurrence of reduction was confi rmed by calculating the chemical potential of ethanol and methanol as well as
spectra of plasma emission in the temperature range 1500–2000 K. Characterization of synthesized nanoparticles
was carried out by energy-dispersive X-ray spectrometry and transmission electron microscopy.
Author:
N. Amaliyah, I. Rahim, A. E. Eka Putra,a S. Mukasa, S. Nomura, and H. Toyota
Keywords:
zinc nanoparticles, in-liquid plasma, alcohol solvent, reduction, microwave plasma
Page:
1467
STRUCTURE OF THE DETACHED GAS–DROPLET FLOW AND HEAT TRANSFER IN AN AXISYMMETRIC CONFUSER
Results of a numerical investigation of the infl uence of a negative longitudinal pressure gradient, arising at an
abruptly enlarged cross section of a pipe with an axisymmetric confuser, on the structure of the turbulent gas–
droplet fl ow and the heat transfer in the confuser of the pipe are presented. It is shown that a favorable pressure
gradient in such a pipe signifi cantly infl uences the characteristics of the two-phase fl ow and the heat transfer in its
confuser. An increase in the convergence angle of the confuser in this pipe leads to a decrease in the turbulence of
the gas–droplet fl ow in it by more than four times compared to the turbulence of the gas–droplet fl ow downstream
of an abruptly enlarged cross section of an analogous pipe with no convergence (φ = 0o
). It was established that the
recirculation zone in the gas–droplet fl ow in the confuser is substantially smaller in length (by 30%) and the point
at which the heat transfer in it reaches a maximum is shifted somewhat downstream, as compared to those in the
gradient-free detached gas–droplet fl ow in the pipe with no convergence, and the coordinate of the maximum heat
transfer in the confuser is practically coincident with the coordinate of the attachment of the detached two-phase
fl ow in it.
Author:
M. A. Pakhomov and V. I. Terekhov
Keywords:
heat and mass transfer, confuser, fl ow separation, abrupt enlargement, numerical simulation
Page:
1473
SIMULATION OF NONSTATIONARY TURBULENT FLOWS IN DEVICES FOR REDUCING THE NOISE LEVEL OF HIGH-PRESSURE GAS MEDIA MOVING WITH A HIGH VELOCITY
Features of the simulation of the thermodynamic and gasdynamic processes occurring in devices for reducing the
noise level of a shot from a gun were considered. A simulation of large vortices in the nonstationary turbulent fl ow
of powder gases in a muzzle noise reduction device with a silencer representing a shaped channel with several
chambers, whose volumes decrease in the direction to the silencer outlet, has been performed. Results of qualitative
and quantitative investigations of the initiation, development, and damping of the shock waves in the fl ow of powder
gases, formed as a result of the fi ring of a shot made from a signal gun, are presented.
Author:
K. N. Volkov, V. N. Emel′yanov, D. É. L′vov, and P. S. Chernyshov
Keywords:
numerical simulation, turbulent fl ow, multichamber channel, shot, noise, silencer, shock wave.
Page:
1484
EXPERIMENTAL AND THEORETICAL INVESTIGATIONS OF THE SPECIFIC FEATURES OF HIGH-VELOCITY MOTION OF SUPERCAVITATING STRIKERS MADE OF VARIOUS MATERIALS IN WATER
Results are presented of an experimental-theoretical investigation of the motion in water of supercavitating strikers
made of steel and aluminum and tungsten (TNI, i.e., tungsten, nickel, and iron) alloys in a broad velocity range.
Estimates have been made of the ranges of velocities of entry into water in which the investigated supercavitating
strikers from various materials are not destroyed and preserve the original shape. Experimental and computational
data have been obtained on the value of deviation of the trajectories of two simultaneously starting from each other
supercavitating strikers at the initial stage of their group motion in water depending on the materials they are
made of
Author:
S. A. Afanas′eva, I. S. Bondarchuk, V. V. Burkin, A. S. D′yachkovskii, A. N. Ishchenko, K. S. Rogaev, A. Yu. Sammel′, A. D. Sidorov, E. Ya. Stepanov, and A. V. Chupashev
Keywords:
supercavitating striker, fabrication material, launching velocity, high-velocity entry into water, group motion in water
Page:
1494
PROPAGATION OF DETONATION WAVES IN A BUBBLE LIQUID WITH INHOMOGENEOUS DISTRIBUTION OF VOLUME CONTENT
The propagation of detonation waves in a plane rectangular channel fi lled with a bubble fl ammable liquid with
inhomogeneous distribution of the volume content of a gas phase is investigated. It is shown that the gas phase
inhomogeneity leads to the focusing of the pressure wave into the region of larger volume content and to the
subsequent initiation of bubble detonation. It is established that because of the gas phase inhomogeneity, a decrease
occurs in the amplitude of the initiating wave capable of initiating detonation.
Author:
I. K. Gimaltdinov, A. A. Gimaltdinova, and E. Yu. Kochanova
Keywords:
bubble liquid, waves, two-dimensionality, detonation failure, channel of complex shape
Page:
1504
CONTROL OVER CONVECTIVE AND RADIATIVE HEAT TRANSFER IN POROUS METAMATERIALS AND ON METASURFACES OBTAINED BY SELECTIVE LASER MELTINA
At present, an intense development occurs in investigations of metamaterials having unique properties that
depend on their micro- and nanogeometry. Additive technologies, especially in selective laser melting, open ample
opportunities for creating such metallic metamaterials. The presented investigation deals with processes of heat
transfer of metamaterials with gyroid-type microgeometry
Author:
A.S. Boreisho, G. T. Dzhgamadze, A. A. Moiseev,b A. V. Savin,a,b P. G. Smirnov, S. S. Smolentsev, and A. A. Filatov
Keywords:
selective laser melting, metamaterials, k–ω SST turbulence model, convective heat transfer, large eddy simulation (LES), Nusselt number, radiative heat transfer, emissive power
Page:
1511
MATHEMATICAL MODELING OF UNSATURATED FILTRATION IN SWELLING SOILS USING THE CAPILLARY-RISE PROBLEM AS AN EXAMPLE
A mathematical model of unsaturated fi ltration in swelling soils has been developed under the conditions of constancy
of the entire volume of the medium. On the basis of the developed model, a solution to the problem on capillary rise of
moisture in swelling soils has been obtained and characteristic features of the process have been established. A series
of experiments on capillary rise of moisture in swelling and unswelling soils has been conducted. A comparison of
solutions to the capillary-rise problem with experimental data has been made. Good agreement has been shown
between the experimental data and the solutions to corresponding boundary-value problems.
Author:
N. E. Galiullina, M. G. Khramchenkov, and R. M. Usmanova
Keywords:
moisture transport, soil, basic hydrophysical characteristics of soil, fi ltration, capillary rise.
Page:
1519
INFLUENCE OF POROUS STRUCTURE HETEROGENEITY ON THE DYNAMICS OF DEVELOPMENT OF INTERFACIAL CONTACTS IN TWO-PHASE FLOWS WITH VISCOUS AND CAPILLARY FINGERS
An investigation of the effect of capillary and viscous forces on the dynamics of the development of two types of
interfacial contacts "injected fl uid–ejected fl uid" and "injected fl uid–solid body" in the case of two-phase fl ows
in porous media with different heterogeneities of the pore structure is carried out. The connection between the
dynamics of development of interfaces, distribution of fl uids in the pore space of samples and the average size
of pore channels fi lled with the injected fl uid is being established. To simulate a two-phase fl ow the present work
resorts to the lattice Boltzmann equations together with the multirelaxation time collision operator, as well as the
color fi eld gradient model for describing the effects of interfacial interaction. The relationship between the capillary
and viscous forces is controlled by fl ow velocity and interfacial tension. Computational experiments are carried
out on artifi cial digital models of porous media with the use of the Monte Carlo algorithm. The heterogeneity of
porous structures is described numerically with the aid of the randomness coeffi cient calculated as the standard
deviation of local porosity measured in Voronoi′s cells. A linear law of the development of the specifi c length of
interfacial "fl uid–fl uid" and "fl uid–solid body" contacts has been established. The two-phase fl ow parameters and
the heterogeneity of the pore structure exert their effect only on the dynamics of the growth of the interface length. An
increase in the heterogeneity of the pore structure contributes to the growth of the mean size of pore channels fi lled
with injected fl uid. The randomness coeffi cient exerts an insignifi cant effect on the dynamics of the development of
the "fl uid–fl uid" contact and a negative effect on the dynamics of the development of the "fl uid–solid body" interface.
In transition from fl ow with viscous fi ngers to a regime with capillary fi ngers, a signifi cant decrease in the dynamics
of development of the "fl uid–fl uid" contact and an increase in the dynamics of the development of the "fl uid–solid
body" interface are observed.
Author:
T. R. Zakirov and M. G. Khramchenkov
Keywords:
interfacial contacts, two-phase fl ows, porous media, heterogeneity, lattice Boltzmann equation
Page:
1526
COMPUTER DIAGNOSTICS OF THE PROCESS OF DOUBLE-ACTION PRESSING OF POWDER MATERIALS UNDER DRY-FRICTION CONDITIONS
Consideration is given to the process of double-action pressing of powder materials possessing plasticity and
compressibility. Account is taken of the infl uence of dry external friction between the material and the lateral walls
of the mold, which determines the strong linearity, of the problem in question. Based on computer animation with
specialized graphics software packages, the authors have gained clear ideas of the kineti of compaction of a material
and have identifi ed the qualitative features of stage development of the propagation of a compaction wave in the
material's volume due to the three-dimensional nonstationary character of the process of pressing. To calculate the
stressed-strained state of a powder material, use was made of a linear combination of the Fleck–Kuhn–McMeeking
and Gurson–Tvergaard–Needleman models, which makes it possible to take account of the wide range of variation
in the porosity of materials. Numerical solution of the problem was implemented by a fi nite-element analysis with
isoparametric elements. The increment in plastic strains at each step was determined from nonlinear plastic-fl ow
equations. The distributions of the equivalent stresses and of the value of volume plastic strains in the material have
been investigated, and the nonuniformity of the relative density over the height and along the radius of a billet at the
end of the period of pressing has also been shown. The obtained results are relevant for predicting optimum regimes
of the process of double-action pressing under dry-friction conditions.
Author:
S. V. Karpov, A. M. Stolin, and L. S. Stel'makh
Keywords:
powder material, double-action pressing, compacting, friction, modeling, Fleck–Kuhn–McMeeking model, Gurson–Tvergaard–Needleman model
Page:
1542
WETTING OF HYDROPHOBIC AND HYDROPHILIC COATINGS
A technology of formation of a superhydrophobic coating has been presented which is based on a combination of
mechanical punching and vapor deposition of carbon nanoparticles. Contact angles for hydrophobic coatings have
been measured. Transport properties of hydrophilic porous coatings from aluminum-oxide nanoparticles have been
investigated. A method to increase the height of rise of a liquid by forming microtrenches in the coating has been
proposed. The height of capillary rise for coatings with microtrenches has been measured.
Author:
Yu. A. Kuzma-Kichta, N. S. Ivanov, D. V. Chugunkov and A. V. Lavrikov
Keywords:
hydrophobicity, hydrophilicity, capillary rise, contact angle, wetting, transport of a liquid, condensation, evaporation.
Page:
1549
RESULTS OF CHEMICAL ACTIVATION OF BIOCHAR OBTAINED BY THE METHOD OF ACCELERATED HYDROTHERMAL CARBONIZATION OF SEWAGE SLUDGE
An investigation has been made into accelerated hydrothermal fl uidized carbonization of sewage sludge in a superheated steam medium. It is shown that an increase in the process temperature has no effect on its duration but has a signifi cant effect on the composition of noncondensable gases. Biochar activation has been investigated in potassium hydroxide at a temperature of 750o
C and the biochar–KOH ratios of 1:1.5, 1:2, and 1:3. It is shown that
the KOH concentration has no effect, in practice, on the sorption characteristics of the obtained product which is
more suitable for the use as a soil improver
Author:
N. S. Muratova, R. L. Is′emin, A. V. Melezhik, S. N. Kuz′min, A. V. Nebyvaev, A. V. Mikhalev, O. Yu. Milovanov, V. S. Kokh-Tatarenko, Yu. A. Teplitskii, É. K. Buchilko, E. A. Pitsukha, and A. Zh. Greben′kov
Keywords:
hydrothermal carbonization, fl uidized bed, superheated steam, waste water, chemical activation, adsorption
Page:
1557
PROPAGATION OF ACOUSTIC WAVES IN A WATER-SATURATED POROUS MEDIUM FORMED BY A GAS HYDRATE
The propagation of acoustic waves in a porous medium whose skeleton consists of a gas hydrate with pores fi lled
with water has been studied. A system of equations is written that describes the propagation of acoustic waves
in such a porous medium. A dispersion equation is obtained, on the basis of which the phase velocity of sound
and the decrement of attenuation of acoustic waves are analyzed. The coeffi cients of refl ection and passage at the
"liquid–porous medium" and "porous medium–liquid" interfaces have been derived and investigated. Based on the
dispersion equation and corresponding refl ection and passage coeffi cients, the propagation of the fi nite-duration
pulses in the porous medium is investigated. The possibility of estimating the thickness of the gas hydrate bed with
the aid of acoustic waves is shown.
Author:
V. L. Dmitriev, I. G. Khusainov, and I. K. Gimaltdinov
Keywords:
acoustic waves, porous medium, gas hydrate, dispersion relation, refl ection and passage coeffi cients, fast Fourier transform
Page:
1563
INFLUENCE OF THE HEAT OF PHASE TRANSITION ON THE ONSET OF FILTRATION CONVECTION IN MIXTURES OF LIQUIDS WITH LIMITED MUTUAL SOLUBILITY
Consideration is given to the problem on the convective stability of mechanical equilibrium of a mixture of liquids
with limited mutual solubility in a porous medium. It is assumed that in the initial state of mechanical equilibrium,
the mixture fi lls the horizontal porous layer and is separated into two phases: the upper lighter phase and the lower
heavy one. At the lower boundary of the layer, the higher temperature is maintained than that at the upper boundary.
A study is made of the infl uence of the heat of phase transition and the ratio of phase densities on conditions for the
onset of convection and on the structure of occurring fl ows.
Author:
M. M. Ramazanov and N. S. Bulgakova
Keywords:
heat of transition, fi ltration convection, mixtures of liquids with limited solubility
Page:
1571
SPECIFIC FEATURES OF COMBINED HYDROTHERMAL CARBONIZATION OF POULTRY LITTER AND SAWDUST
An experimental investigation has been conducted into combined hydrothermal fl uidized carbonization of poultry
litter and sawdust in a superheated steam medium. The effects of temperature on the duration of the process of
hydrothermal carbonization have been identifi ed, and the composition of the noncondensable gaseous products of
carbonization has been established
Author:
R. L. Is′emin, S. N. Kuz′min, A. V. Nebyvaev, N. S. Muratova, A. V. Mikhalev, O. Yu. Milovanov, V. S. Kokh-Tatarenko, Yu. A. Teplitskii, É. K. Buchilko, E. A. Pitsukha, A. Zh. Greben′kov, and F. Marias
Keywords:
hydrothermal carbonization, fl uidized bed, superheated steam, poultry litter, sawdust, noncondensable gases, biochar
Page:
1582
IDENTIFICATION OF THERMOPHYSICAL CHARACTERISTICS OF CHEMICALLY INTERACTING MATERIALS OF HEAT-PROTECTIVE COATINGS
The high-priority task of creating effi cient thermal protection of various-purpose objects from direct external hightemperature effects is studied. This article proposes a solution to the problem of identifying the thermophysical
properties of the materials, which decompose in the course of the chemical interaction and which are used in heatshielding structures. The admissible temperature conditions of a protected object are provided by a multicomponent
heat-shielding coating, the components of which, when the temperature threshold is reached, enter into a twostage endothermic reaction with absorption of excessive heat. The thermophysical characteristics of a heatprotective coating to be identifi ed are determined by the solution of the corresponding inverse thermal conductivity
problem formulated in a minimax variation form relative to the discrepancy between the results of thermophysical
experiment and of mathematical simulation. The parametrization of the identifi able equivalent heat capacity
narrows the domain of the search for solutions to a collection of piecewise continuous functions and reduces the
set original variational problem to the parametric problem of semi-infi nite optimization, whose solution, based
on rather general alternative properties of the optimal temperature residual, makes it possible to minimize this
residual in a uniform evaluation metric.
Author:
N. S. Al′debenev, S. Yu. Ganigin, D. A. Demoretskii, A. N. Diligenskaya, and M. Yu. Lifshits
Keywords:
heat shielding, thermophysical properties, boundary-value problem, identifi cation, heat-protective coating, inverse problem
Page:
1590
RADIATIVE-OPTICAL AND THERMOPHYSICAL CHARACTERISTICS OF FIBROUS SILICA-BASED HEAT INSULATION
Results of computational and experimental determination of spectral optical parameters, i.e., the indices of scattering and absorption, of two types of silica-based fi brous heat insulation have been given. Materials fabricated
from quartz and silica fi bers have been considered. The optical parameters in the range of wavelengths 1–4.7 μm
were determined by solution of the inverse problem from experimental data for the spectral coeffi cient of total
refl ection. The inverse problem was solved by minimization of the residual functional between the experimental
and calculated spectra of refl ection coeffi cients of the materials′ layers of several thicknesses. The spectra of the
total-refl ection coeffi cients were measured on a Fourier spectrometer with an integrating sphere in the range of
wavelengths 1–18 μm. To calculate the spectral refl ection coeffi cient, use was made of the invariant embedding
method. By the spectral optical parameters, the authors have assessed the radiative thermal conductivity in the
Rosseland approximation and the integral emissive power of material layers of different thicknesses in the range of
temperature 20–1100o
C. The calculated radiative thermal conductivity has been compared with the experimental
data on the effective thermal conductivity measured by the method of a quasi-stationary thermal regime.
Author:
R. A. Mironov, V. O. Gaidenko, M. O. Zabezhailov, O. V. Tomchani, V. V. Cherepanov, and O. M. Alifanov
Keywords:
optical properties of fi brous heat insulation, partially transparent materials, inverse problems of radiation transfer, radiative-conductive heat transfer
Page:
1600
EFFECTS OF PROTONE IRRADIATION ON THE STRUCTURAL-PHASE STATE OF NANOSTRUCTURED TIZRSIN COATINGS AND THEIR MECHANICAL PROPERTIES
The method of reactive magnetron sputtering has been used to form nanostructured TiZrSiN coatings on various types of substrates (templates) in nitrogen-defi cit and stoichiometric concentration regimes. Methods of scanning electron microscopy and roentgenostructural (x-ray diffraction, XRD) phase (-shift) analysis have been used to identify the structural-phase state of the initial coatings, their thickness, and also morphology. Using the Oliver and Pharr nanoindentation techniques and also tribomechanical tests, the hardness, Young′s modulus, and the friction coeffi cient of coatings have been identifi ed. Irradiation of the investigated TiZrSiN coatings by H+ hydrogen ions with an energy of 500 keV in the fl uence range from 1·1016 to 1·1017 ion/cm2
has been conducted at an AN 2500
accelerator facility. It has been established that nanostructured TiZrSiN coatings applied in nitrogen-defi cit and
stoichiometry regimes are radiation-resistant and potentially promising for operation as protective coatings on the
airframes of small fl ight vehicles in the earth orbit and in the outer space conditions.
Author:
F. F. Komarov, S. V. Konstantinov, V. A. Zaikov, and V. V. Pil′ko
Keywords:
nanostructured TiZrSiN coatings, structural-phase state, tribomechanical properties, nanoindentation, radiation resistance
Page:
1609
STRUCTURE AND PROPERTIES OF POLYMER COMPOSITES BASED ON POLYTETRAFLUOROETHYLENE AND COBALT, TITANIUM, AND SILICON NANOPARTICLES
The results of studies of the structure and properties of composite materials based on polytetrafl uoroethylene and fi llers consisting of composites of ultrafi ne polytetrafl uoroethylene and titanium and silicon nanoparticles obtained by pyrolytic refi ning of a mixture of powders of polytetrafl uoroethylene and fl uorides (NH4)2SiF6 and (NH4)2TiF6,
as well as cobalt nanoparticles obtained by the method of thermal decomposition of cobalt nitrate on the surface
of polytetrafl uoroethylene microgranules, are presented. Investigations carried out by the x-ray structure analysis,
x-ray phase analysis, and IR spectroscopy methods have made it possible to fi nd the composition and structure
of nanoparticles containing Co, Ti, Si and their interaction with the polymer matrix. In addition, the dielectric
and thermophysical properties of the composites obtained were studied. Using the methods of differential scanning
calorimetry and plotting the isometric heating diagrams, the heat resistance and internal orientational stresses were
determined. The thermal conductivity data was obtained using an information and measuring system of nondestructive
control of the thermophysical properties of solid materials. Measurements of the permittivity of composites were
performed by the noncontact method in a fl at condenser, and the wear resistance was estimated in the mode of
abrasive wear. As a result of the studies carried out, the characteristic features of the properties of composites were
identifi ed depending on the type and concentration of inorganic fi ller and the technology of obtaining composites.
Some of the characteristics of the created composites (deformation heat resistance, thermal conductivity, and wear
resistance) exceed those of the starting polytetrafl uoroethylene.
Author:
G. S. Baronin, V. M. Buznik, S. V. Mishchenko, and D. O. Zavrazhin
Keywords:
nanocomposites based on fl uoropolymer; cobalt, titanium, and silicon nanoparticles; tribotechnical, thermophysical, and dielectric properties.
Page:
1619
MAGNETOTHERMOELASTIC WAVES IN A ROTATING ORTHOTROPIC MEDIUM WITH DIFFUSION
In this paper, the governing partial differential equations for a rotating orthotropic magnetothermoelastic medium
with diffusion are proposed on the basis of the Lord–Shulman theory of generalized thermoelasticity and the velocity
equation is obtained. The plane wave solution of this equation is indicative of the existence of four quasi-plane
waves, namely, quasi-longitudinal displacement (qLD), quasi-thermal (qT), quasi-mass diffusion (qMD), and quasitransverse displacement (qTD) waves. The real values of the wave speeds are calculated for a particular material,
and the effects of anisotropy, as well as of the diffusion, magnetic, and rotation parameters and the angle of incidence
on the speeds are shown graphically
Author:
A. K. Yadav
Keywords:
thermoelasticity, orthotropic medium, diffusion, rotation, magnetic fi eld, speed, plane waves.
Page:
1628