Volume 98, №4
THERMODYNAMIC OPTIMIZATION OF HEAT-TRANSFER STRUCTURES
The authors have obtained parameters of prototype heat-transfer structures, that correspond to the minimum entro-
py production (dissipation) at prescribed heat load and heat-transfer coefficient. The latter is related to the contact
surface, which is in turn correlated with the cost of the heat-exchange system. Dissipation, at prescribed heat load
and heat-transfer coefficient, is bounded below, and the heat load corresponding to this bound is the highest possi-
ble for this heat-transfer coefficient. Account has been taken of the influence of the hydrodynamics of flows and of
the change in their phase state
Author:
A. M. Tsirlin, R. S. Gevorkyan
Keywords:
multiflow heat transfer, heat load, energy dissipation, thermal conductivity, optimum heat-exchange system, entropy, condensation and evaporation of flows
Page:
861
CALCULATION OF A CASCADE OF ONE OR SEVERAL TYPES OF STAGES BY THE NUMBER OF GAS CENTRIFUGES FOR MULTICOMPONENT SEPARATION
A method has been proposed for calculating a cascade with one or several types of stages according to the number
of gas centrifuges, variable separation factors of the stages, and prescribed concentrations of the target isotope
in outgoing flows. The method ensures determining the effective parameters of the cascade of gas centrifuges in
a prescribed configuration based on the calculated feed flows of the stages, that vary in individual portions of
the cascade. A computational experiment has been conducted on separation of germanium tetrafluoride. With the
example of concentrating 70 Ge, the characteristic features of cascades have been shown
Author:
V. A. Palkin
Keywords:
separation of isotopes, cascade, gas centrifuge, germanium isotopes
Page:
869
GENERALIZED APPROACH TO CALCULATING THE PARAMETERS OF A QUASI-IDEAL CASCADE WITH A PRESCRIBED NUMBER OF STAGES AND PRESCRIBED CONCENTRATIONS OF THE TARGET COMPONENT IN OUTGOING FLOWS
A generalized model of a quasi-ideal cascade with different values of the mass number of the reference component
for different portions of the cascade has been proposed. A procedure has been developed to find such a set of pa-
rameters of the cascade at which one can ensure obtaining prescribed concentrations of the target components in
its outgoing flows at prescribed integral numbers of stages in each of its sections.
A possibility has been shown to optimize this cascade for prescribed concentrations of the target com-
ponent in outgoing flows through the exhaustion of different combinations of lengths of cascade sections with
prescribed concentrations of the target component in its outgoing flows. The developed approach to optimizing a
sectioned quasi-ideal cascade makes it possible to reduce the number of variables when the optimum parameters
ensuring prescribed concentrations of the target component in the outgoing flows are assessed.
Author:
A. Yu. Smirnov, G. A. Sulaberidze, T. É. Azizov
Keywords:
separation of isotopes, quasi-ideal cascade, multicomponent mixture
Page:
877
ON THE EQUIVALENCE OF THE SOLUTIONS OF NONLINEAR PROBLEMS BY THE HE VARIATIONAL ITERATION METHOD AND THE TEMIMI–ANSARI METHOD: TRANSFER PHENOMENA
Approximate solutions of a number of nonlinear problems (heat-transfer, reaction diffusion, thin-film boiling) have
been obtained using the Temimi–Ansari method and the He variational iteration method. The solutions of such
problems by the indicated methods were found to be identical, and, in the case of small iterations, they did not
provide a useful approximation either in the sense of convergent series or in the sense of asymptotic ones. It was
shown that the obtaining of the indicated solutions with the use of a large number of iterations is practically
impossible because of the extreme cumbersomeness of the computational procedure. Nevertheless, the Temimi–
Ansari method offers an important advantage over the He method in that it does not involve the search for an
optimum Lagrange multiplier and, at the same time, provides a simple iteration scheme of obtaining a system of
recursion linear equations solved fairly easily.
Author:
V. A. Kot
Keywords:
nonlinear differential equations, nonlinear problems, approximate solution, iterative method, thermophysical problems, heat transfer, reaction diffusion, thin-film boiling
Page:
889
FEATURES OF THERMAL COOXIDATION OF COMPONENTS OF ALTERNATIVE LIQUID FUELS
Results of experimental studies of the characteristics of separate thermal oxidation and cooxidation of advanced
components of alternative liquid fuels have been presented with the example of brown coal, water, and waste motor
oil. The temperature range in the experiment was 25–1100 o C. The influence of the properties of the components
of the fuels on the characteristics of thermal cooxidation as part of the blend has been established. The use of the
addition of waste motor oil as part of the composite fuel allows reducing the burnout temperature by 18% compared
to coal, and also decreasing activation energy at the stages of volatile yield and thermal oxidation of solid carbon
residue by 43 and 52% respectively. Synergetic effects of thermal cooxidation of components of fuel blends have
been singled out. The value of the synergetic effect resulting from the cocombustion of components as part of the
composite fuel amounts to as much as 1.72 and 1.92% when the suspension fuels "60% coal and 40% water" and
"50% coal, 40% water, and 10% oil" are used
Author:
V. V. Dorokhov, D. S. Romanov, P. A. Strizhak
Keywords:
composite liquid fuel, brown coal, water, waste oil, thermal oxidation
Page:
914
DETAILED ANALYSIS OF THE ENERGY EFFICIENCY OF AN INCOMPLETE THERMODYNAMIC CYCLE WITH DETONATION COMBUSTION
A new approach is suggested to assessing the efficiency of a detonation jet engine, which is determined as a ratio of
the combustion products′ work in the process of their isentropic expansion to the heat of combustion. A comparison
is made of the energy efficiency in constant-volume combustion and in a detonation wave with a subsequent release
of detonation products into the surrounding environment. The calculation of the efficiency of detonation combustion
is performed on the basis of an exact solution of a self-similar problem of propagation of infinitely thin Chapman–
Jouguet detonation in a tube with an end wall. It is shown that the absolute advantage of Chapman–Jouguet
detonation which has been established for a full cycle is achieved due to transformation of the kinetic energy of
the detonation products into useful work and that in the case of an incomplete thermodynamic cycle, detonation
combustion turns out less efficient than constant-volume combustion. An analysis has been made of a detonation
cycle compared to Otto and Brayton cycles at a limited degree of pressure rise, maximum temperatures and indicated
efficiency and arbitrary independent energy parameters (amount of heat supplied during combustion). It has been
established that at the adopted limitations, the detonation cycle does not have an absolute advantage over the Otto
and Brayton cycles. The detonation cycle surpasses the said cycles in the values of the thermal efficiency, maximum
pressure and the criterion of irreversibility; in terms of the value of specific volume work (work-to-volume ratio)
the detonation cycle surpasses the Brayton cycle but is outperformed by the Otto cycle
Author:
Yu. V. Tunik, M. S. Assad
Keywords:
energy efficiency, detonation adiabat, Chapman–Jouguet detonation, Poisson adiabat, self-similar solution, constant-volume combustion, isentropic expansion, Otto and Brayton cycles, thermal efficiency
Page:
920
EFFECT OF ENGINE PERFORMANCE AND STATISTICAL ANALYSIS OF EMISSION POWERED BY CHICKEN FAT BLENDED BIODIESEL
Alternative waste oils are increasingly combined with diesel fuel and used as biodiesel in combustion engines to lower exhaust emissions. One such waste oil that can be combined with diesel to enhance emission profiles is chicken fat, a poultry industry’s byproduct. The performance of chicken fat–diesel blends and their effect on exhaust emissions in a diesel engine with a variable compression ratio (VCR) are examined in this study. The tested blends representing 5% to 30% chicken fat combined with diesel oil are CB5, CB10, CB15, CB20, CB25, and CB30. The experimental setup was first validated using a pure diesel, and then different chicken fat blends were assessed. Interestingly, NO x emissions were observed to increase with higher biodiesel concentrations. Specifically, the CB25 and CB30 blends emitted 2.5% and 2.98% NO x , respectively, compared to conventional diesel. The blend CB5 shown by 0.02% in CO 2 emissions, while CB30 demonstrated the hihgest emissions by 0.16%. The blend
CB10 was the best choice out of all the blends because it provided a balanced increase in emission reduction
with advantageous cost implications. The study shows that chicken fat biodiesel, especially the CB10 blend, is a
promising substitute fuel that can significantly lower exhaust emissions and support more environmentally friendly
energy sources
Author:
Mahammadsalman Warimani, Anfas Mukram Thattoth, Fharukh Ahmed G. M., c Sayed Ahmed Imran Bellary, d Ashish Shinde, e Zahir Hasan, f Noor Alam, Sonachalam Muthuswamy
Keywords:
alternate fuel, diesel oil, chicken fat, exhaust emission, brake power efficiency
Page:
936
SPACE–TIME EVOLUTION OF A RADIOACTIVE LABEL DURING THE INJECTION OF A TRACER INTO A WELL
The results of modeling the flow of an indicator radioactive liquid in a well with account for convective and diffu-
sive mass transfer, as well as the decay of the tracer substance, are presented. Based on the asymptotic method, an
analytical solution to the problem has been constructed for the case of arbitrary radial velocity distribution in the
borehole, computational experiments have been performed, and the results of analyzing the contribution by various
processes to the formation of concentration fields during the movement of the tracer tag in the process of liquid
injection have been provided.
It is shown that the main criterion determining the evolution of a rectangular label is convective-diffusive
processes whose contribution is determined by the Ma number. To account for the contribution of decay processes,
it is necessary to use an additional criterion, Fi. The contribution of radioactive decay leads to a decrease in am-
plitude values, and the shape of the label is determined by the values of the convective-diffusive number and time.
New patterns have been established for the formation of fields of radioactive elements during the movement
of the tag along the borehole. It is shown that the evolution of a "rectangular" radioactive tracer tag in the initial
state is accompanied by its lag relative to the injected liquid and the formation of a tail part where the maximum
concentration values are basically observed.
The developed mathematical model and software can be used to create a simulator which is used to
carry out the planning and interpretation of the results of tracer analysis in the diagnostics of the well′s technical
condition, casing faults, annular circulation, and tracer injection to determine the characteristics of formations.
Author:
A. I. Filippov, M. A. Zelenova, R. G. Gubaidullin
Keywords:
radioactive tracer, convective diffusion, asymptotic method, concentration field, well
Page:
946
MATHEMATICAL MODELING OF THE PROCESS OF INJECTING THERMOGEL-FORMING COMPOSITIONS INTO A STRATIFIED NONUNIFORM FORMATION
The article is devoted to modeling the process of injecting thermogel-forming compositions into a vertical injection
well that uncovers a stratified-nonuniform formation with an inhomogeneous temperature field. By integrating
thermal and hydrodynamic problems, analytical solutions are obtained that allow modeling the forming of a gel
barrier in the course of time. Using the mass conservation law, expressions are determined for the water flow rate
into each seam after treatment, and formulas are obtained for calculating changes in bottomhole pressure and
water content in the process of gel barrier formation.
It is shown that the steady-state distribution of the formed gel concentration is determined by two opposite
effects. On the one hand, the formation temperature increases with distance from the injection well, while, on the
other hand, the concentration of the thermogel-forming composition decreases, so that a maximum is observed in
the distribution of the concentration of the gel formed. Calculations of the dynamics of water content show that
the formation of a gel barrier in a highly permeable layer is accompanied by a redistribution of water flows and
a maximum decrease in water content in the product. The formation of a gel barrier in a low-permeability layer
is accompanied by a slight increase in water content, but largely determines the final effect of using thermogel-
forming compositions.
Author:
I. V. Vydysh, K. M. Fedorov, T. A. Kremleva
Keywords:
technology of leveling the intake profile, thermogel-forming compositions, gel formation on a change in temperature, stratified -onuniform formation, low-permeability gel barrier, redistribution of flows, reduction in water content
Page:
957
INJECTION OF SUPERHEATED STEAM INTO A GAS-HYDRATE STRATUM
By mathematical-modeling methods, the authors investigate the process of injection of superheated steam into a
gas-hydrate stratum. In constructing a mathematical model, it has been assumed that phase transitions (of conden-
sation of vapor and evaporation of water and of formation and decomposition of methane hydrate) occur in certain
finite volumes of a porous medium that are determined in the course of the solution of the problem with the phase
saturations, rather than on frontal surfaces. On the basis of numerical solutions, it has been shown that near the
boundary of injection of the steam, a complete decomposition of methane hydrate occurs on the frontal surface, in
practice. Here, near the boundary of extraction of the gas, the decomposition of methane hydrate occurs in the vol-
ume region, which is due to the reduction in the pressure. It has been shown that the increase in both the injection
pressure of the steam and its temperature has no substantial effect on the amount of methane hydrate decomposing
in the stratum. It has been established that the increase in the permeability of the stratum leads to a greater heating
of the stratum and a larger amount of the decomposed gas hydrate
Author:
M. K. Khasanov, S. L. Borodin, M. V. Stolpovskii
Keywords:
gas hydrate, decomposition of gas hydrate, porous medium, injection, steam, condensation, gas-hydrate stratum
Page:
967
INTERPRETATION OF THE RESULTS OF GAS-HYDRODYNAMIC STUDIES OF VERTICAL WELLS IN A FRACTURED-POROUS FORMATION
Mathematical modeling of real gas filtration to a vertical well in a fractured-porous formation has been performed.
The curves of change in time of the well bottom pressure and its time derivatives depending on the filtration
parameters of the formation have been analyzed. A method for interpreting the results of gas-hydrodynamic studies
of vertical wells penetrating fractured-porous formations has been proposed based on the theory of solving inverse
problems.
Author:
M. N. Shamsiev, V. R. Gadil′shina, A. I. Abdullin, A. V. Nasybullin
Keywords:
fractured-porous formation, wells, pressure, real gas, gas-hydrodynamic studies, inverse problem
Page:
979
FILTRATION OF A GAS LEAVING AN UNDERGROUND STORAGE RESERVOIR
The process of gas outflow from an underground storage reservoir has been modeled. The conditions for the ex-
istence and the laws governing the shock wave motion have been elucidated. The results obtained (the time of
complete storage discharge, the maximum gas temperature behind the shock wave) have been generalized within
the framework of the similarity theory. It has been established that this temperature does not depend on the particle
size and is determined by the Hugoniot relations
Author:
Yu. S. Teplitskii, E. A. Pitsukha, A. R. Roslik
Keywords:
granular bed, filtration, underground reservoir, discharge time, resistance force, modeling, shock wave, compression wave, attenuation, similarity numbers, amplitude
Page:
988
MICROMECHANICS OF THE MODIFICATION OF PHYSICOCHEMICAL AND TECHNOLOGICAL PROPERTIES OF SWELLING CLAYS
Consideration has been given to a model of formation of the microstructure of swelling clays on the basis of ideas
about the action of disjoining pressure between the microparticles of clay minerals. Consideration has been given
to cases of the formation of stable and unstable packings of microparticles and the transition of a structure of one
type to a structure of another type. Data are presented on the use of the constructed model for control of the quality
of clay raw material in construction and oil-producing industries
Author:
M. G. Khramchenkov, F. A. Trofimova, R. É. Dolgopolov
Keywords:
montmorillonite, microstructure, micromechanics, swelling, exchange capacity, exchange power, clays, active surface, technological properties
Page:
996
INVESTIGATING DIMENSIONAL KINETIC EFFECTS ON THE BASIS OF MICROSCOPIC OBSERVATIONS OF THE EVOLUTION OF AN ENSEMBLE OF DROPLETS
The influence of geometric characteristics on the properties of a substance and the dynamics of physicochemical
processes is manifested in the form of dimensionless effects which turn out to be substantial in many natural
and technological processes. Investigating dimensional kinetic effects is complicated by the difficulty with
obtaining experimental data on the state of individual dispersed particles of nano-, pico-, and femtoliter volumes.
This problem is solved by the proposed procedure which is based on obtaining and analyzing a sequence of
microphotographs of a polydisperse ensemble of droplets. A result is the construction of kinetic curves describing
the behavior of a substance in variously sized droplets with comparable conditions. The analysis of the kinetic
curves allows obtaining quantitative characteristics necessary to reveal the dimensional dependence of the
physicochemical characteristics of the substance, to determine the kinetic parameters of chemical reactions, and
to construct mathematical models of the processes in disperse systems. Observations of the ensembles of droplets
have revealed a number of unusual kinetic effects ("non-Ostwald" behavior, oscillatory phase transformations
"gas–liquid–crystal," and the formation of satellite droplets)
Author:
V. B. Fedoseev, E. N. Fedoseeva
Keywords:
dimensional effects, modeling, physicochemical processes, an ensemble of particles, analysis of images, microscopy
Page:
1005
DYNAMIC MEMBRANE BASED ON SUSPENSION OF DIETARY FIBERS FOR MICROFILTRATION OF MILK WHEY
The formation of dynamic membranes from a finely ground suspension of citrus dietary fibers on the surface of a
tubular ceramic membrane (CM) was studied. A dynamic membrane can be used for microfiltration of milk whey to
prevent the buildup of protein deposits on the ceramic membrane and in its pores. The average size of suspension
particles was found to be 4.4
m and the particle size distribution was determined by using photon correlation
spectroscopy. The rheological characteristics of the suspension were determined, and it was shown that it is a
gel-like system with a dry matter concentration of 3–6%. Determining the dependence of normal flow on filtration
parameters, testing dynamic membranes under repeated pressure surges, and measuring membrane permeability
under significant tangential flow and countercurrent flow made it possible to establish a qualitative picture of
dynamic membrane formation and destruction. The layer of particles on the ceramic membrane is retained by two
types of contacts: contacts between particles trapped in the ceramic membrane pores with overlying particles and
lateral contacts. They are successively destroyed with increasing tangential flow velocity. A model of destruction
of the dynamic membrane by tangential flow and countercurrent flow is proposed, the calculations for which are
consistent with experimental data
Author:
S. A. Titov, S. V. Shakhov, D. S. Saiko, I. A. Glotova, A. S. Chervinskaya, N. N. Korysheva
Keywords:
membrane permeability, model, tubular membrane, dynamic membrane, pulse backpressure, protein deposits
Page:
1014
A CONJUGATE MODEL OF FILM CONDENSATION OF SATURATED VAPOR ON A FLAT NONUNIFORMLY HEATED SURFACE
In a numerical experiment, the process of condensate film formation on a horizontal heat-conducting plate is con-
sidered. The rate of condensate growth is investigated in the thin-film approximation. The proposed mathematical
model of condensation allows one to take into account the inhomogeneous heating of the underlying surface. The
model is intermediate between integral or quasi-one-dimensional models and models developed within the frame-
work of computational fluid dynamics with account for the condensate film flow and processes in the vapor cushion.
The calculation results are validated using experimental data obtained in studying propane condensation on a
copper plate. Heat removal from the underlying surface in the experiment was carried out using Peltier elements.
The mass of the resulting condensate was chosen as a control parameter. With regard to condensation on a flat hor-
izontal surface, the use of the model allows one, in a number of cases, to increase the accuracy of determining the
condensate mass in comparison with an analytical calculation that does not take into account the inhomogeneity of
the temperature field in the underlying surface
Author:
A. A. Kuroedov, A. S. Vasyutichev, A. V. Ananiev, I. V. Laptev
Keywords:
film condensation, evaporative fuel supply system, spacecraft, propane.
Page:
1024
NUMERICAL STUDY OF LAMINAR-TURBULENT TRANSITION IN PROBLEMS OF CONVECTIVE-RADIATIVE HEAT TRANSFER
Numerical modeling of the process of combined heat transfer by natural convection and thermal surface radiation
was performed. The velocity vector components were calculated from the mesoscopic distribution function of
conditional particles within the framework of the lattice Boltzmann method. On the other hand, the calculation of
the thermodynamic characteristics of the thermogravitational flow was carried out by a finite-difference solution
of the macroscopic energy equation. The developed hybrid algorithm, simulating the direct numerical modeling
method, was tested on reference experimental data on turbulent natural convection in a closed rectangular cavity
that were obtained by other researchers. The range of variation of the Rayleigh number, conductive-radiative
parameter and wall emissivity was 4·10 4 ≤ Ra ≤ 10 9 , 55.84 ≤ N r ≤ 163.448 and 0 ≤ ε ≤ 1, respectively. In the course
of numerical modeling it was established that the process of convective-radiative heat transfer in a closed square
cavity with lateral heating/cooling becomes nonstationary at Ra ≥ 6·10 7 and N r ≥ 63.95. In this case, the evolution
trend of the average convective and effective Nusselt numbers acquires an oscillatory character with a constant
amplitude of oscillations in the range of 6·10 8 ≤ Ra ≤ 10 9 , 63.95 ≤ N r ≤ 75.89.
Author:
A. É. Nee
Keywords:
lattice Boltzmann method, finite difference method, natural convection, surface radiation
Page:
1034
SUBLIMABLE AND DEGRADABLE THERMAL PROTECTION MATERIALS IN AEROSPACE TECHNOLOGY
Theoretical models of the aerothermochemical interaction between the streamlined surface of a flying vehicle and
the dissociated air in the case of combustion and sublimation are presented. Methods and results of investigations
were generalized with the aim to obtain a solution on the basis of the similitude method for the case of combustion
and sublimation, e.g., of the graphite at an arbitrary cross section of a flying vehicle, around which air flows in the
laminar regime at large Reynolds numbers. For different heat-resistant coatings found under the hypersonic-flow
conditions varying within a wide range, calculations of the mass flow, the heat flow, and the friction drag coefficient,
whose results are related by the universal dependences expressed in terms of the stagnation enthalpy, the local
pressure, the velocity gradient, the pressure gradient parameter, and the surface temperature, are presented. The
thermophysical properties as well as the kinetic constants of thermoelastic materials at temperatures falling within
a wide range were investigated
Author:
N. I. Sidnyaev, L. S. Sklyarinskii
Keywords:
aero-thermochanics, thermal protection materials, simulation, sublimation, hypersound
Page:
1042
DESIGN CALCULATIONS OF ENCLOSING STRUCTURES AND THE HEAT POWER OF THE HEATING SYSTEM OF A BUILDING
The paper presents the results of thermotechnical calculations of outer multilayer enclosing structures and the
heat power of the heating system of a residential building, including calculations of temperature fields and partial
pressures of water vapor at various parameters of the structural layers and thermal insulation layers. Consideration
has been given to options and an assessment has been made of the effects of varying the parameters and different
locations of the thermal insulation in the outer multilayer enclosing structures on the changes of temperature fields
and partial pressures of water vapor in the cladding and also on the change of the heat power of the heating system
of spaces in the building for two climatological design areas. The calculations were performed under the below
methods using a specially designed computer software program.
Author:
A. A. Kudinov, S. K. Ziganshina
Keywords:
buildings, enclosing structures, thermal insulation, thermotechnical calculation, resistance to heat transfer, temperature field, diffusion of water vapors, dew point, heating system, heat power
Page:
1054
INFLUENCE OF MAGNETIC FIELD ON HEAT EXCHANGE OF LIQUID IN A SPHERICAL LAYER AT LOW MAGNETIC REYNOLDS NUMBERS
The paper presents the results of mathematical modeling of convective heat exchange and magnetic hydrodynamics
of liquid in a spherical layer. The influence of boundary conditions for the azimuthal component of magnetic
induction on the heat exchange of an electrically conductive liquid, the structure of its flow, the field of magnetic
induction, and the distribution of local Nusselt numbers for the case of magnetic Reynolds numbers less than one
is investigated. The values of magnetic Reynolds numbers and the moments of time at which the intensity of heat
exchange on the inner and outer surfaces of the liquid layer becomes the same are determined
Author:
S. V. Soloviev
Keywords:
mathematical modeling, nonstationary convective heat exchange, magnetic hydrodynamics, spherical layer
Page:
1063
MODELING OF DISPERSED FLOWS IN A STEAM–AIR MEDIUM FOR WET COOLING TOWER ELEMENTS
The organization of thermoconvective flow in a wet cooling tower in working condition and without drop structure
is determined. The dependence of temperature gradient on the inner walls of the cooling tower on the maximum
flow velocity in its volume is considered. The results of modeling the operation of the cooling tower are presented
in the form of 3D models with display of volume concentrations of drops and vapor of moisture
Author:
A. G. Trifonov, A. S. Khod'ko
Keywords:
atomic electric power plant, cooling tower, mathematical and physical models, 3D model, convective flows, steam–air mixture, dispersed flows
Page:
1074
APPROXIMATE MODEL OF THE ABSORPTION OF MICROWAVE RADIATION BY THE PLASMA FORMED NEAR AN ANTENNA-INITIATOR FOR PROBLEMS ON ANALYSIS OF COMBUSTION
Simulation of the propagation of microwave radiation through a plasma region in the presence of an initiator of
a discharge has been performed. A region occupied by plasma and its conductivity were defined starting from the
criterion of the balance between the integral rates of the reactions in the plasma. For determining the distribution
of the strength of the electromagnetic field near an antenna-initiator with regard for the conducting region specified,
the Helmholtz equation was solved. By the determined distributions of the electric field strength in plasma, the
power of its Joule heating and the coefficients of the plasma-chemical reactions, averaged over the volume of the
plasma region, were calculated. The results obtained are of interest for simulating the gas dynamics of combustion
of fuel mixtures ignited by a microwave discharge
Author:
P. V. Bulat, M. E. Renev
Keywords:
plasma, microwave discharge, propane–air mixture, Joule heating, reaction coefficient, discharge initiator
Page:
1079
DYNAMICS OF CHARGES OF ELECTRON AND ION FLOWS IN A LASER PLASMA SOURCE FOR THE FORMATION OF NANOSTRUCTURES
Based on conducted experiments, causes have been found for distorting the shape of the ion flux pulse supplied
to the substrate in a laser plasma source for applying nanocoatings at low accelerating potentials; ways of their
elimination are suggested. The design capacity of a laser plasma source, which is ~40 nF, has been determined,
which is important for the conduct of subsequent experiments. It is shown that in eliminating the ion current pulse-
shape distortion, a more uniform ion flow is supplied to the substrate surface, which results in an increase of the
efficiency of the process of applying thin uniform nanocoatings.
Author:
V. K. Goncharov, M. V. Puzyrev
Keywords:
laser plasma, ion flows, nanostructures
Page:
1089
THEORETICAL ANALYSIS AND CASE STUDIES OF ONE-DIMENSIONAL ION EXTRACTION PROCESSES
The ion extraction process is one of the most important procedures in laser-induced isotope separation. In our
previous study, based on the analysis of sheath evolution and ion rarefaction wave propagation, a theoretical model
has been developed for describing the one-dimensional ion extraction process. In this paper, two case studies are
conducted by employing this analytical model. Firstly, barium plasma is selected, since previous experimental
studies are focused mainly on barium plasmas. A comparison between the analytical and experimental results is
made to validate this theoretical model. For a more practical scenario, uranium plasmas are considered, and a
systematic analysis of the impact of initial plasma parameters on the ion extraction characteristics is made. The
results provide a brief and clear physical description of the one-dimensional ion extraction process, and also
provide a guidance for improving the ion extraction efficiency in actual applications.
Author:
Yao-Ting Wang, Lan-Yue Luo, He-Ping Li, Dong-Jun Jiang, and Ming-Sheng Zhou
Keywords:
ion extraction process, analytical model, theoretical analysis
Page:
1099
PROPAGATION OF SHOCK WAVES IN WEAKLY CONDUCTING NONIDEAL GAS IN THE PRESENCE OF AZIMUTHAL AND AXIAL MAGNETIC INDUCTIONS
A similarity solution of the problem on a cylindrical shock wave in weakly conducting nonideal gas, acted upon by
axial and azimuthal magnetic inductions, has been obtained in the power-law shock path approximation with the
use of the Lie group invariance method. Since inadequate magnetic freezing is produced by a weakly conducting
medium, to obtain a similarity solution of the problem, it was assumed that the density of the ambient medium is
constant and the azimuthal and axial magnetic inductions in this medium are varying. The forms of the expressions
for the indicated inductions were determined. The Lie group invariance approach was applied to a system of partial
differential equations, with the result that a system of ordinary differential equations has been obtained, and it was
solved numerically. The influence of the parameters of a nonideal gas and the ratio between the specific heats on
the strength of a shock wave in the gas and on the flow was investigated. It is shown that the strength of a shock
wave increases with increase in the nonidealness parameter but the ratio between the specific heats has a decaying
effect on the shock wave
Author:
G. Nath, V. S. Kadam
Keywords:
A similarity solution of the problem on a cylindrical shock wave in weakly conducting nonideal gas, acted upon by axial and azimuthal magnetic inductions, has been obtained in the power-law shock path approximation with the use of the Lie group invariance method. Since inadequate magnetic freezing is produced by a weakly conducting medium, to obtain a similarity solution of the problem, it was assumed that the density of the ambient medium is constant and the azimuthal and axial magnetic inductions in this medium are varying. The forms of the expressions for the indicated inductions were determined. The Lie group invariance approach was applied to a system of partial differential equations, with the result that a system of ordinary differential equations has been obtained, and it was solved numerically. The influence of the parameters of a nonideal gas and the ratio between the specific heats on the strength of a shock wave in the gas and on the flow was investigated. It is shown that the strength of a shock wave increases with increase in the nonidealness parameter but the ratio between the specific heats has a decaying effect on the shock wave
Page:
1109
MATHEMATICAL MODEL OF HEAT AND MASS EXCHANGE AND OF AEROSOL SEPARATION IN AXIAL AND TWISTED DISPERSED-ANNULAR GAS AND LIQUID FLOWS
The paper presents systems of equations for a numerical and approximate mathematical model of combined
processes of heat and mass exchange during contact cooling of gases and heating of liquid, as well as turbulent
transfer and deposition of particles on a film in a vertical ascending dispersed-annular flow in a cylindrical
channel. The numerical model is based on a system of partial differential equations in a two-dimensional form with
boundary conditions of the fourth kind. The approximate model is constructed using a mathematical model of ideal
displacement of gas and liquid, where the main parameters are the coefficients of heat and mass emission and of
turbulent-inertial transfer of particles. Studying is carried out of transfer phenomena during contact condensation
cooling of liquids (using water), as well as of gas purification from the finely dispersed phase (aerosol separation).
The gas phase can be flue or process gas, and the aerosol particles can be small droplets and solid particles.
Examples of determining the thermal and separation efficiency of processes in axial and swirling flows of gas and
liquid are shown. The devices developed by the authors have been implemented at various enterprises
Author:
A. G. Laptev, E. A. Lapteva
Keywords:
heat and mass exchange, aerosol separation, mathematical model, efficiency of processes, gas cooling
Page:
1120
ON ONE HYPERBOLIC MODEL OF A ONE-VELOCITY HETEROGENEOUS MEDIUM
Consideration has been given to a model of a one-velocity multicomponent heterogeneous mixture, whose
differential equations are derived from the Nigmatulin multivelocity nonhyperbolic nonconservative model
with interfractional-interaction forces introduced additionally and ensuring equal accelerations for different-
density components of the mixture. The characteristic analysis has been made of the equations of an equilibrium
model and their hyperbolicity has been shown. In integrating the model′s equations, use was made of the
multidimensional nodal method of characteristics which is based on the splitting, along coordinate directions, of
the initial system of equations into a number of one-dimensional subsystems, each being solved using the inverse
method of characteristics. With this approach, the author has calculated the problem of interaction of a shock
wave propagating in unperturbed air and a layer of sulfur-fluoride gas located along the solid wall. The shock-
wave interaction pattern has been described in detail.
Author:
V. S. Surov
Keywords:
hyperbolic model, one-velocity multicomponent mixture, multidimensional nodal method of characteristics
Page:
1130
INTERACTION OF METAL MELT WITH A QUASI-SOLID FILM ON ITS SURFACE IN AN ALTERNATING MAGNETIC FIELD WITH CHANGING AMPLITUDE
The paper presents a mathematical model describing heat and mass transfer in a metal melt and elastically stressed
states of a film on its surface in the presence of an alternating magnetic field. The stability of the oxide film on
the melt surface is investigated at different magnetic field strengths and frequencies. The loading and destruction
of thin films on the melt surface during its moving are considered. The mechanisms responsible for the primary
destruction of the original film and its fragments are revealed. The frequency range of the magnetic field is found
in which the film on the surface of the metal melt is strong enough to prevent intensification of the melt flow with an
increase in the magnetic field strength, which contributes to the integrity of the film itself.
Author:
induction melting, metal melt, oxide film, nonstationary flow, forced convection, Lorentz force, stress- strain state
Keywords:
I. L. Nikulin, V. A. Demin, S. A. Nikulina
Page:
1140
EXPERIMENTAL SUBSTANTIATION OF THE POSSIBILITY OF IMPROVEMENT OF THE OUT-OF-PLANE THERMOPHYSICAL PROPERTIES OF A HYBRID STRUCTURE OF A RADIATION HEAT EXCHANGER
The prospective program of the deployment of a manned lunar base has revealed the need for developing a new
elemental composition for a thermal control system (TCS). For a TCS radiation heat exchanger (RHE), to reduce
the mass and to improve the reliability of operation under the conditions of the lunar surface, it is suggested that an
RHE radiant duralumin panel with heat pipes be replaced with a high-conductivity radiant panel of hybrid structure
on the basis of pyrolytic graphite. A hybrid panel has a substantial anisotropy of thermophysical properties. The
thermal conductivity along the panel plane exceeds the cross-field thermal conductivity almost one hundred times.
To improve the out-of-plane thermophysical properties of a hybrid panel, it is suggested that the panel be pierced
with metal elements. The presented paper is devoted to determining the thermophysical properties of a graphite-
based anisotropic hybrid structure pierced with metal elements perpendicular to the plane. To determine the thermal
diffusivity and thermal conductivity of the samples, use was made of an unsteady laser flash method. Approximations
have been obtained for the temperature dependences of in-plane and out-of-plane thermal diffusivity and thermal
conductivity of a hybrid pyrolytic graphite structure for the temperature range of 256–372 K.
Author:
A. E. Belyavskii, N. S. Kudryavtseva
Keywords:
anisotropic hybrid structure, thermal conductivity, thermal diffusivity, laser flash method, radiation heat exchanger
Page:
1152
EFFECTS OF THE TEMPERATURE OF A HYBRID BIOMATERIAL NANOFLUID AND THE VOLUME FRACTION OF NANOPARTICLES ON ITS VISCOSITY
The nanoparticles of palm kernel, snail, and periwinkle shells have been synthesized for the first time for the
preparation of nanofluids, and the viscosity of the resultant nanofluids was measured. The experiments were conducted
at temperatures, varying from 30 to 70 o C, for different volume fractions of nanoparticles in the nanofluids. It was
established that the viscosity of the nanofluids of the indicated biomaterials, prepared on the basis of deionized
water and ethylene glycol (50:50), increases with increase in the volume fractions of nanoparticles in them, and it
exponentially decreases with increase in the temperature of the nanofluids.
Author:
B. U. Oreko, A. A. Okafor, C. O. Mgbemena
Keywords:
viscosity, nanofluids, biomaterials, nanoparticles, palm kernel, periwinkle, and snail shells, ethylene glycol, deionized water
Page:
1159
INFLUENCE OF SACCHARIN ON THE COMPOSITION, STRUCTURE, AND RATE OF ELECTROCHEMICAL DEPOSITION OF FILMS BASED ON Ni AND Fe
This paper is devoted to the study of the effect exerted by saccharin on the processes of electrochemical deposition
of nickel- and iron-based films. In this work, experiments were carried out using different electrolyte composi-
tions and current densities, analyzing their effect on the composition, structure and rate of film formation. The
results obtained allow a deeper understanding of the mechanisms of electrochemical deposition and optimization
of the process conditions to achieve the desired properties of Ni- and Fe-based films. This work has potential
application in areas where control of the composition and structure of surface coatings plays a key role, such as
electrocatalysis, microelectronics, magnetic protective coatings, electrochemical devices, and other technological
applications.
Author:
T. I. Rakovets, T. I. Zubar, M. I. Panasyuk, V. A. Fed′kin, O. D. Kanaf′ev, A. N. Kotel′nikova, A. V. Trukhanov, V. M. Fedosyuk
Keywords:
NiFe films, electrochemical deposition, saccharin, chemical composition, speed, microstructure
Page:
1166