HEAT AND MASS TRANSFER IN POROUS AND DISPERSIVE MEDIA MODELING OF THE PROCESS OF HEAT AND MASS TRANSFER OF TRANSPIRATION-COOLING SYSTEMS IN THE PRESENCE OF PERIODIC PERTURBATIONS
A. N. Golovanov and A. S. Yakimov UDC 536.46:536.245.022
Consideration has been given to the interaction between transpiration-cooling systems and a high-enthalpy
pulsating gas flow. The possibility of controlling the process of heat and mass exchange in a thermal protective
material has been investigated.
Keywords: thermal protective material, pulsating gas flow, heat and mass exchange.
ON THE EVALUATION OF THE TIME OF PERIODICAL DISSOLUTION OF A DISPERSED MATERIAL IN A ROTOR-PULSE DEVICE
A. V. Fedorov,a A. V. Shul’gin,a M. S. Vasilishin,b
D. B. Ivanova,b O. S. Ivanov,b and A. G. Karpovb
UDC 532.695
Results are presented of experimental and numerical investigations of the kinetics of periodical dissolution of
benzoic and salicylic acids in water using the rotor-pulse device. It is found that the process obeys the firstorder
kinetics. A determining influence of the rotation frequency of the device rotor and the size of the radial
gap between the rotor and the stator on the dissolution time is shown. Favorable agreement between the experimental
and calculated time dependences for the concentration of the dissolved substance are obtained.
Keywords: rotor-pulse device, dissolution, kinetics.
EVAPORATION OF A PICOLITER DROPLET ON A WETTED SUBSTRATE AT REDUCED PRESSURE
V. I. Saverchenko, S. P. Fisenko,
and Yu. A. Khodyko
UDC 536.423:66.048.5
The results of theoretical and experimental investigation of the evaporation of picoliter water droplets on a
substrate at reduced pressure (20–80 Torr) have been given. The substrate temperature varied in the range
25–40oC. The calculations have been carried out in a free-molecular approximation. It has been shown that
the evaporation time sharply decreases if the average droplet height is less than 10 μm and is a few milliseconds
for a 5-μm-high droplet. It has been experimentally and theoretically shown that for droplets higher
than 10 μm, the evaporation time is a few seconds in the investigated pressure range.
Keywords: diameter of the base, average height, evaporation time, surface temperature of the droplet, substrate
temperature, time reversal.
MODELING THE HYDRODYNAMICS AND THE PROCESS OF AVERAGING A HIGHLY CONCENTRATED GRANULATED MEDIUM IN POWDER TECHNOLOGY APPARATUSES
A. V. Shvab, M. S. Martsenko,
and Yu. N. Ryzhikh
UDC 532.135+678.053.3
Investigation of the hydrodynamics and of the process of averaging a highly concentrated granulated loose
medium in a vertical rectangular channel with a sudden contraction has been carried out on the basis of the
model of a viscous nonlinear fluid. The characteristic features of the model of motion of such a medium consists
in taking the slipping of particles on solid surfaces into account by introducing an independent empirical
coefficient. The validity of numerical results was checked by comparing with the well-known experimental
data. Based on the hydrodynamics obtained, the modeling of the process of averaging a granulated medium
is presented, the intensity of which was analyzed depending on the regime parameters of flow.
Keywords: non-Newtonian fluid, velocity, concentration, granulated medium, slip conditions, averaging of a
mixture, inhomogeneity factor.
HEAT EXCHANGE IN GRANULAR-BED TUBES
Yu. S. Teplitskii and M. V. Vinogradova UDC 532.546
The results of investigations of the wall and total coefficients of heat exchange of a granular bed with the
tube wall is analyzed. The generalized dependences for calculation of these parameters, which have been
checked in a wide range of experimental conditions, are obtained. The limiting values of the coefficient of
wall heat exchange at small Reynolds numbers are established from the experiments of N. V. Antonishin and
associates on nonstationary heat exchange in an unblown granular bed. The influence of the longitudinal
thermal conductivity of the bed on the calculated values of the wall heat-exchange coefficient is shown.
Keywords: quiescent granular bed, wall heat exchange, total heat exchange.
MATHEMATICAL MODELING OF FLOWS FROM CANALS
E ′. N. Bereslavskii UDC 532.546
In the hydrodynamic formulation, two-dimensional steady filtration in homogeneous isotropic ground from canals
through a soil layer to the underlying highly permeable pressure water-bearing stratum is considered in
the presence of the ground capillarity and evaporation from the free surface. To study filtration, a combined
multiparametric boundary-value problem of the theory of analytical functions is formulated, which is solved
using the P. Ya. Polubarinova-Kochina method and procedures of conformal mapping of regions of a special
kind that are characteristic of the problems of subsurface hydromechanics. On the basis of this model an algorithm
of calculating the capillary water spreading and the filtration discharge is developed for the situations
where in water filtration from canals provision is made for the ground capillarity, evaporation from
the free-surface of groundwater, and the additional pressure from the side of water of the underlying wellpermeable
bed. With the aid of the obtained accurate analytical relations and numerical calculations a hydrodynamic
analysis is made of the structure and character of specific features of the modeled process as well
as of the effect of all physical parameters of the scheme on the filtration characteristics.
Keywords: filtration, groundwater, ground capillarity, evaporation, pressure, complex velocity.
CHARACTERIZATION OF THE INFLUENCE OF CARBON NANOMATERIALS ON THE MECHANICAL BEHAVIOR OF CEMENT STONE
J. Eberhardsteiner,a S. Zhdanok,b B. Khroustalev,c
E. Batsianouski,c S. Leonovich,c and P. Samtsoub
UDC 621.762; 691.002(032)
The influence of adding carbon nanomaterials to a cement stone on the mechanical properties of the latter
has been studied. Two test methods have been used: nanoindentation and ultrasonic testing. The obtained results
were compared with those of other authors.
Keywords: carbon nanomaterials, cement paste, nanoindentation, ultrasonic test.
HEAT AND MASS EXCHANGE IN THE PERIOD OF DECREASING DRYING RATE BY THE
REGULAR-MODE METHOD
A. I. Ol’shanskii and V. I. Ol’shanskii UDC 66.047.37
Consideration is given to the method of calculation of the kinetics of drying of moist materials by the G. M.
Kondratiev method of a regular mode.
Keywords: heating rate, Biot number, Kondratiev number, Rehbinder number, Nusselt number, fundamental drying-
kinetics equation.
ACTION OF HIGHLY CONCENTRATED ENERGY FLUXES ON MATERIALS NUMERICAL MODELING OF THERMOMECHANICAL PROCESSES IN ABSORPTION OF LASER RADIATION IN SPATIALLY INHOMOGENEOUS MEDIA
O. G. Romanov,a G. I. Zheltov,b
and G. S. Romanovc
UDC 535.21;534
A numerical model making it possible to consider, with exhaustive completeness, processes that occur in the
absorbing spatially inhomogeneous liquid medium on exposure to pulsed laser radiation has been presented.
Numerical experiments have shown the efficiency of the presented procedure of calculation in a wide range of
pulse durations (from micro- to femtosecond ones) and for typical energy parameters of laser systems.
Keywords: optoacoustic effect, numerical methods, pulsed laser radiation.
START OF CONDENSATION IN EROSIONAL JETS OF METALS SUBJECTED TO HIGHLY INTENSE SUBMICROSECOND LASER ACTION
V. K. Goncharov, K. V. Kozadaev,
and D. V. Shchegrikovich
UDC 621.373.826.004.14
Using the technique of laser probing, the time dependences of the transparency factor, integral glow, and of
the scattered component of probing radiation for erosional laser jets of metals exposed to intense submicrosecond
laser pulses have been determined. Based on the results of laser probing, a conclusion on the condensation
nature of the process of formation of a liquid-droplet phase of the target-material under the given
conditions of laser action has been drawn.
Keywords: laser erosion of metals, submicrosecond pulses of optical radiation, condensed phase of the target
material.
NONREFLECTIVE PASSAGE OF ELECTROMAGNETIC RADIATION ON ITS INCIDENCE AT AN ANGLE ON THE ABSORBING LAYER OF A DIELECTRIC
R. M. Kasimov and S. R. Kasimova UDC 621.365
The conditions of nonreflective passage of an electromagnetic wave on its incidence at an angle on a plane
layer of an absorbing dielectric applied to an infinitely thick nonabsorbing backing have been found. Their
dependences on the coating layer thickness, angle of wave incidence, and on the dielectric properties of the
backing and coating materials are investigated.
Keywords: cancellation of electromagnetic waves, incidence of a wave at an angle.
NONREFLECTIVE ABSORPTION OF AN ELECTROMAGNETIC WAVE IN ITS INCIDENCE ON THE TWO-LAYER SYSTEM "MAGNETIC–METAL" AT AN ANGLE
R. M. Kasimov and S. R. Kasimova UDC 621.365
The conditions of nonreflective absorption of an electromagnetic wave in its incidence, at an angle, on a
plane layer of absorbing magnetic applied to a metal substrate are found. The dependences of these conditions
on the angle of incidence of the wave, the thickness of the layer, and the magnetic properties of the
coating material are investigated. The possibility of separating a prescribed polarization component of the incident
radiation with the use of the phenomenon of nonreflective wave absorption in the magnetic–metal system
is considered.
Keywords: absorption of an electromagnetic wave, incidence of the wave at an angle.
PENETRATION OF ELECTROMAGNETIC WAVES THROUGH COMPOSITE SCREENS CONTAINING IDEALLY CONDUCTING HELICES
V. T. Erofeenko, V. I. Demidchik,
S. V. Malyi, and R. V. Kornev
UDC 517.958:537.8
A complex procedure of numerical analytical modeling of the interaction of elecromagnetic fields with the
plane layer of a composite material containing conducting helices has been presented. The procedure involves
determination of the effective electromagnetic parameters of composite materials containing stochastically distributed
thin-wire elements with the use of Pocklington’s equation. As a result the medium with helical inclusions
has been replaced by the equivalent homogeneous chiral medium characterized by the effective
parameters. The coefficients of reflection and transmission of waves by a screen have numerically been investigated.
Keywords: Maxwell equation, electromagnetic fields, diffraction problem, screen, helical inclusions, composite,
chiral medium.
HYDRODYNAMICS IN TECHNOLOGICAL PROCESSES HYDRODYNAMIC MECHANISMS OF THE INFLUENCE OF INJECTION ON THE CLASSIFICATION CHARACTERISTICS OF A HYDROCYCLONE
L. L. Min’kov,a A. V. Krokhina,b
and J. Dueckc
UDC 532.542.4:575.5, 519.63
The hydromechanics in a hydrocyclone with an injector is investigated on the basis of the performed experiments
and mathematical modeling. Special emphasis is placed on elucidation of the mechanisms of action of
injection on the restructuring of hydrodynamic fields and finally on the mechanisms of classification of particles
in the hydrocyclone.
Keywords: hydrocyclone, injector, radial and tangential injections, split-parameter, numerical modeling, experiment,
turbulent diffusion, separation grain, separation function.
TOWARD THE THEORY OF CONVECTION IN A ROTATING STRATIFIED MEDIUM
OVER A THERMALLY INHOMOGENEOUS HORIZONTAL SURFACE
L. Kh. Ingel’ and M. V. Belyaeva UDC 532.517.013.4+551.558
Stationary convection in a rotating medium uniformly heated from above and nonuniformly cooled from below
has been studied analytically in the linear approximation. As distinct from a number of previous works, the
case of the presence of both a stable background stratification and of intense rotation around a vertical axis
has been analyzed. One of the interesting properties of the solution found is that despite the stable stratification
the perturbations of temperature, pressure, and of the vertical velocity over the thermal inhomogeneities
of the horizontal surface, in the case of strong rotation, penetrate deep into the medium (up to heights of the
order of the horizontal scales of the inhomogeneities mentioned.) The ascending motions over the "warm spot"
transfer relatively cold volumes of the medium upwards, so that beginning from a certain level a vast "cold"
region can be formed and the related positive deviation of pressure (of the weight of the medium column).
This leads to the formation of the anticyclonic vortex perturbation.
Keywords: convection, horizontal thermal inhomogeneities, rotating stratified media, linear approximation, analytical
solutions.
SIMULATION OF THE SUPERSONIC TURBULENT FLOW AROUND A CYLINDER WITH COAXIAL DISKS
S. A. Isaev,a Yu. M. Lipnitskii,b A. N. Mikhalev,c
A. V. Panasenko,b and A. E. Usachovd
UDC 532.517:4
The turbulent axisymmetric flow around a stepped body — a cylinder with coaxial front and rear disks — has
been calculated with the aid of a VP2/3 package based on multiblock computational technologies and the
generalized procedure of pressure correction. The computational model has been tested with the example of a
supersonic flow around a sphere. The numerical forecasts made with the use of Spalart–Allmares shear stress
transfer and eddy viscosity transfer models have been compared with the data of the aeroballistic experiment,
wind tunnel tests, and the results of the calculation of the flow around the disk–cylinder arrangement by a
simplified zonal model in a wide range of variation of the incident flow Mach number (from 1.5 to 4). We
have obtained a good agreement between the calculated transverse flow density distributions in the front stalling
zone and those determined from the interferograms for the wave-drag-rational disk–cylinder arrangement.
The influence of the rear disk on the drag of the disk–cylinder–disk arrangement has been estimated.
Keywords: decrease in the motive drag, stepped bodies, supersonic flow, turbulence, shock wave, calculation,
multiblock computational technologies, Menter model, Spalart–Allmaras model, aeroballistic experiment, wind
tunnel tests.
TOWARD THE CALCULATION OF FLOWS OF A ONE-VELOCITY MULTICOMPONENT
MIXTURE BY THE MODIFIED S. K. GODUNOV METHOD
V. S. Surov UDC 532.529.5
Different variants of the Godunov method that describe the flow of a one-velocity multicomponent mixture for
nondivergent systems are compared. In calculation of the Riemann problems, an approximate method of computations
based on the characteristic relations was employed.
Keywords: one-velocity multicomponent medium, hyperbolic systems of nondivergent form, approximate Riemann’s
solver, numerical simulation.
THERMAL PRODUCT ESTIMATION METHOD FOR AERODYNAMICS EXPERIMENTS
H. A. Mohammed, H. Salleh,
and M. Z. Yusoff
UDC 536.2
This paper presents an experimental technique to estimate the appropriate thermal product values of rugged
and fast response temperature probes (TPs) for hypersonic aerodynamic experiments. Two types of scratches
were used, mainly abrasive papers with different grit sizes and scalpel blades with different thicknesses, to
form the probe junction. The effect of the scratch technique on the probe’s thermal product is investigated.
The probes are tested and calibrated in the test section and in the end wall of shock tube facility. It is observed
that the thermal product of a particular TP depends on the Mach number, junction scratch technique,
and junction location, as well as on the enthalpy conditions. It is noted that, depending on the scratch technique,
some of the TPs do not require individual calibration; however, calibration for others is likely to be
needed.
Keywords: Experimental technique; thermal product; temperature probe; hypersonic aerodynamics flow; shock
tube.
CONTROL OF THE PROFILE OF THE IMPURITY DISTRIBUTION IN EPITAXIAL LAYERS GROWN FROM A SOLUTION-MELT WITH REGULATED VOLUME AND COMPOSITION
A. V. Karimov, D. M. Yodgorova,
and O. A. Abdulkhaev
UDC 621.382:621.315.592
The possibilities of obtaining linear and nonlinear profiles of the impurity distribution by liquid epitaxy are
studied. Analytical expressions are obtained for the profile of the impurity distribution in epitaxial layers
grown from solutions-melts with a constant volume and with a varying volume, where a variation in the volume
of the basic solution-melt and in the amount of the doping impurity in it is achieved by mixing, to it, an
additional saturated solution through the capillary opening. It is shown that in this case the profile of the impurity
distribution is determined by the velocity of feed of the additional solution-melt. Comparisons of experimental
data with calculated results are presented.
Keywords: liquid epitaxy, profile of impurity distributions, distribution coefficient, solution-melt, capillary opening,
mixing.
FLOW OF A MICROPOLAR FLUID OVER A CURVED STRETCHING SURFACE
M. Sajid,a N. Ali,b Z. Abbas,b
and T. Javedb
UDC 536.25
The paper is devoted to the numerical solution of the problem of flow of a micropolar fluid over a curved
stretching surface. A similarity transformation is applied to reduce a system of partial differential equations
to a system of ordinary differential equations. The numerical solution of these coupled equations is carried
out by the shooting method using the Runge–Kutta algorithm. The physical quantities of interest, like the fluid
velocity, microrotation velocity, and pressure, are obtained and discussed as functions of the nondimensional
curvature radius. It is evident from the results that the pressure inside the boundary layer cannot be neglected
for a curved stretching sheet, as distinct from a flat stretching sheet.
Keywords: micropolar fluid, stretching sheet, curved sheet, numerical solution.
Introduction.
DISTRIBUTION OF DISPERSED DROPLETS IN FRAGMENTATION OF THE DROP IN A HIGH-VELOCITY GAS FLOW
A. G. Girin UDC 532.529.6
Within the framework of the model of quasicontinuous fragmentation of a drop, the approximate expression
for the size distribution function of stripped droplets has been found by the mechanism of gradient instability
in high-velocity flows. The intermediate and final distributions obtained for different values of the governing
parameters have been given. A comparison to results of calculations performed according to the overall
scheme demonstrates good agreement in a wide range of parametric values. Certain general features of the
dispersion kinetics have been described.
Keywords: dispersion, gradient instability, daughter droplets, distribution function.
STUDY OF FLOWS IN A CYCLONE CHAMBER
E. A. Pitsukha,a Yu. S. Teplitskii,b
and Yu. V. Zhukovab
UDC 532.529
Parameters of the vortex air flow in an isothermal model of the cyclone chamber are studied. The effect
of the air velocity in nozzles on the values and character of the distribution of pressure and tangential
and longitudinal velocities of air in the chamber is determined. Numerical modeling of the flow is performed,
and it is shown that numerical calculation by the k-w turbulence model is in agreement with experimental
data.
Keywords: cyclone chamber, isothermal model, vortex flow, nozzle, pneumatic probe, central region, peripheral
region.
HEAT AND MASS TRANSFER IN COMBUSTION PROCESSES IGNITION AND COMBUSTION FEATURES OF BIOFUELS
A. F. Ryzhkov, V. E. Silin,
T. F. Bogatova, and S. M. Nadir
UDC 621.039.542.3
This paper presents the results of experimental investigations of the ignition and combustion of plant biofuels
(wood particles, date stones) and products of their mechanical and thermal treatment (pellets, charcoal) at
temperatures typical of the burning process in nonforced furnaces and fixed-bed and fluidized-bed gas producers.
The influence of the furnace heat treatment of a fuel on its inflammation and combustion has been revealed.
The results have been compared with the known data on the burning of pellets, brown coals, and
anthracites and with the calculation by the classical diffusion-kinetic model.
Keywords: biomass, ignition, volatile, regime of combustion, pyrolysis, porosity, self-heating.
MATHEMATICAL MODELING OF THE HEAT TREATMENT AND COMBUSTION OF A COAL
PARTICLE. IV. IGNITION STAGE
Kh. Enkhjargala and V. V. Salomatovb UDC 621.311
The present paper is the continuation of the previous publications of the present authors in the Journal of Engineering
Physics under the general title in which three sequential stages of the thermal preparation of a
carbon particle for combustion are considered: heating, drying, and the yield of volatiles. The present paper
is devoted to a detailed investigation of the stage of ignition of a carbon particle under the conditions of external
radiative-convective supply that most adequately reflects the furnace medium. The characteristics of
thermal ignition of a carbon matrix were studied with the aid of the adiabatic method. Such parameters as
time and the heating temperature, the time of induction, the total time and the temperature of ignition of a
carbon particle, the scale temperature, etc. have been found. The degree of dependence of the time of ignition
on the initial temperature of the particle, the temperature of the external medium, heat transfer coefficient,
and other inlet data has been analyzed.
Keywords: carbon, ignition, mathematical model, heat release, chemical reaction, Arrhenius law.
MATHEMATICAL MODELING OF THE HEAT TREATMENT AND COMBUSTION OF A COAL
PARTICLE. V. BURN-UP STAGE
Kh. Enkhjargala and V. V. Salomatovb UDC 621.311
The present material is a sequel of the previous publications of the authors in this journal under a common
title in which by means of mathematical modeling the sequential stages of the process of combustion of coal
fuels have been obtained: heating, drying, escape of volatiles, and ignition. Mathematical models of the final
stage of combustion of an individual particle — the burn-up stage — have been formulated. On the basis of
the solution methods for nonlinear boundary-value problems developed by us, approximate-analytic formulas
for two characteristic regimes, burn-up simultaneously with the evaporation of the remaining moisture and
burn-up of the completely dried coke residue, have been obtained. The previous history of the physical and
chemical phenomena in the general burning pattern is taken into account. The influence of the ash shell on
the duration of combustion has been extimated. Comparison of calculations by the obtained dependences with
the results of other authors has been made. It showed an accuracy sufficient for engineering applications.
Keywords: coal particle, diffusion and kinetic regimes of combustion, coke residue, ash shell.
ON DETERMINATION OF THE TOXITY INDEX IN STABILIZED LIQUID COMBUSTION IN A ROOM
S. V. Puzach and Dong Viet Mang UDC 614.841
An analysis is performed of thermal gasdynamic conditions for experiments to determine toxity of combustion
products with a fire in a room. Consideration is given to mathematical models of calculating heat and mass
transfer parameters in characteristic small- and large-scale rooms. Results of numerical experiments on determining
the density of carbon oxide formed in combustion of benzene and turbine oil in stabilized combustion
are presented. It is shown that the coefficient of heat loss is a necessary criterion of the equality of toxity indices
in a small-scale experimental setup and in an actual room.
Keywords: fire, toxic gases, toxity index, similarity, heat and mass transfer, coefficient of heat loss, integral
mathematical model, zone mathematical model.
DYNAMIC REGIME OF CONDENSED SUBSTANCE IGNITION UNDER BOUNDARY
CONDITIONS OF THE THIRD KIND
R. Sh. Gainutdinov UDC 536.46
The dynamic problem of ignition of a chemical condensed substance by a convective heat flux when the heat
transfer coefficient α is a power function of time has been solved analytically. The critical conditions of the
thermal ignition of a substance depending on the environmental medium temperature in application to the
specific case of variable heat transfer coefficient were investigated. An engineering method of calculation of
the basic parameters of the thermal ignition of a substance has been proposed.
Keywords: ignition, temperature field, temperature, heat conduction equation, boundary conditions, heat transfer
coefficient, ignition time, heat flux density, thermal conductivity, specific heat, density of a material.
HEAT CONDUCTION AND HEAT EXCHANGE IN TECHNOLOGICAL PROCESSES MODELING OF HEAT-CONDUCTION PROCESSES IN TUBE-SPATIALLY-REINFORCED HYBRID COMPOSITES WITH AN ARBITRARY ANISOTROPY OF THE MATERIALS OF THE COMPOSITION COMPONENTS
A. P. Yankovskii UDC 536.21
A model of heat conduction of a tube-spatially-reinforced medium with a binder dispersely strengthened by
hollow inclusions has been proposed. For the limiting case of degeneration of the tubes into solid fibers, a
comparison has been made of the calculated values of the effective thermal conductivities of unidirectionallyand
cross-reinforced composites to experimental data. Satisfactory agreement of the calculated and experimental
values of these quantities has been shown.
Keywords: heat conduction, composites, spatial reinforcement, hollow fibers, dispersed inclusions, Fourier law,
Stefan–Boltzmann law.
CONTROLLING THE TEMPERATURE REGIME OF THE SOIL MASS IN THE FOUNDATION
OF A BUILDING
A. V. Stepanov,a I. I. Rozhin,b
and F. E. Popenkoc
UDC 624.139:624.15
Using the methods of mathematical simulation, the problem of controlling the temperature of the permafrost
mass in the foundation of a building is investigated. The influence of the thermal insulation embedded in the
foundation, as well as of the lowering of the water table in grounds and of blowing along the day surface with
cold air on the formation of the temperature field and cold accumulation in the soil mass has been studied.
Keywords: foundation of a building, thawing and freezing of permafrost soils, computational experiment.
RADIATION METHODS IN NANOTECHNOLOGY
G. Ya. Gerasimov UDC 541.15
This paper considers the state of the art in the application of radiation technology for obtaining and investigating
new functional materials, devices, and systems of nanometer sizes where the key role is played by the
quantum properties of the substance. This concerns in the first place the production of ion-track membranes,
polymeric nanocomposites and nanogels, three-dimensional nanostructures, finely dispersed powders, semiconductor
nanometric structures, carbon nanostructures, microchips of the new generation based on graphene
transistors, etc.
Keywords: radiation, nanostructured materials, ion-track membranes, polymeric nanocomposites, finely dispersed
powders, carbon nanostructures, lithography, electron beam, ion beams.