Volume 98, №1
NUMERICAL INVESTIGATION OF THE DOWNWARD MERCURY FLOW INSTABILITY IN A NONUNIFORMLY HEATED ROUND TUBE UNDER A TRANSVERSE MAGNETIC FIELD
A numerical study of the downward mercury fl ow in a nonuniformly heated round tube under the infl uence of a transverse magnetic fi eld was carried out using the LES method. The problem was solved in a wall-conjugate formulation with modeling a contamination layer (contact electrical resistance) on the inner surface of the tube wall. The calculations were carried out at the following values of the Reynolds, Prandtl, Grashof, and Hartmann numbers: Re = 104 , Pr = 0.024, Gr = 6·107
, 12·107
, Ha = 0–1000. It is shown that the electrical conductivity of the
contamination layer has a signifi cant eff ect on the stability of the fl ow and the occurrence of abnormally high lowfrequency pulsations in the temperature of the liquid and tube wall.
Author:
M. V. Makarov, G. G. Yankov, V. I. Artemov
Keywords:
LES, conjugate formulation, round tube, mercury, downward fl ow, nonuniform heating around the perimeter, transverse magnetic fi eld, abnormally high temperature pulsations
Page:
1
NUMERICAL SIMULATION OF CONJUGATE HEAT EXCHANGE DURING COOLING OF A HIGH-TEMPERATURE METAL CYLINDER BY A GAS–LIQUID FLOW
The paper presents the results of numerical simulation of heat exchange during cooling of a heated metal cylinder by
a laminar gas–liquid fl ow in a vertical annular channel. The results were obtained based on a mathematical model of
conjugate heat exchange between a gas–liquid fl ow and a metal cylinder in a two-dimensional nonstationary formulation that takes into account the axisymmetry of the ascending fl ow of the cooling medium relative to the longitudinal
axis of the cylinder. The control volume method was used to solve the system of diff erential equations. The fl ow fi eld
parameters were calculated using the SIMPLE algorithm. The Gauss–Seidel method with lower relaxation was used
for the iterative solution of systems of linear algebraic equations. The heat exchange parameters were obtained for
cooling a high-temperature metal cylinder by a gas–liquid fl ow taking into account vaporization. The dynamics of
changes in the structural-phase transformations of the cylinder material depending on the cooling rate is analyzed.
Author:
S. S. Makarov, A. M. Lipanov, A. I. Karpov, M. Yu. Alies
Keywords:
gas–liquid medium, high-temperature metal cylinder, vaporization, conjugate heat exchange, numerical simulation
Page:
18
MATHEMATICAL MODELING OF CRYSTALLIZATION KINETICS OF BULK METALLIC GLASS IN SELECTIVE LASER MELTING
Bulk metallic glasses (BMGs) are promising materials. However, to form an amorphous structure, they require liquid
quenching, which does not allow the production of large bulk products with an amorphous structure. Selective laser
melting (SLM) is an additive technology in which powders are treated layer after layer to form a component according
to a three-dimensional model. In SLM, the cooling rate exceeds the critical cooling rate for BMG, which indicates
a possibility for using SLM for BMG. The purpose of this work is to determine the parameters of crystallization
kinetics in SLM by theoretical analysis of a particular example of the process with subsequent assessment of the
applicability of selected parameters to other samples. A comparison of calculations with an experiment has shown a
broad range of applicability of the obtained parameters.
Author:
M. A. Gridnev, R. S. Khmyrov, A. V. Gusarov
Keywords:
additive technologies, selective laser melting, laser impact, amorphous alloys, bulk metallic glass, crystallization kinetics, heat transfer, mathematical modeling
Page:
26
CALCULATION OF THE TEMPERATURE STATE OF FUEL ELEMENTS IN A COOLING POND OF POWER BLOCK No. 4 OF BELOYARSK NUCLEAR POWER PLANT IN BEYOND-THE-DESIGN ACCIDENT
The temperature state of the spent nuclear fuel (SNF) of the BN-800 reactor was studied under conditions of a
beyond-the-design accident associated with a sudden complete draining of the spent nuclear fuel cooling ponds.
The calculations were performed taking into account natural turbulent convection and thermal radiation for various
values of residual heat release of the spent nuclear fuel. Two accident scenarios were considered with forced
ventilation to the spent nuclear fuel cooling pond and with natural ventilation of the spent nuclear fuel cooling pond,
i.e., under conditions of a complete deenergizing of the spent nuclear fuel storage facility.
For each of the investigated emergency scenarios, stationary temperature fi elds were obtained in the
cooling pond compartment, spent nuclear fuel cans, and spent fuel assemblies, and a conclusion was made
about whether the specifi ed maximum permissible fuel element cladding temperature of 800o
C was reached or not.
Recommendations are given on possible methods for intensifying the cooling of spent fuel assemblies in conditions
of a beyond the design accident.
Author:
E. V. Sadikova, A. A. Pletnev, V. G. Sidorov
Keywords:
spent nuclear fuel, cooling pond, beyond-the-design accident, numerical simulation, heat and mass exchange
Page:
38
EXPERIMENTAL STUDY OF THE INFLUENCE OF FOULING ON THE HEAT TRANSFER OF A SINGLE-ROW HEAT-EXCHANGE BUNDLE OF ROUND-FINNED TUBES UNDER THE CONDITIONS OF ENHANCED FREE CONVECTION
Experimental studies and generalization of the data on heat transfer of a single-row bundle of bimetal tubes with spiral knurled aluminum fi ns and uniform annular interfi n pollution in the regime of free convection to vertical air fl ows created by an exhaust shaft of height H = 0.52–2.24 m with an adjustable fl ow area fh = 0.0087–0.1185 m2
have been presented. The bundle was made of six tubes with a fi nned-surface factor φ = 21.0 and intertube pitch S1 = 64 mm. From the measurement data, the average reduced coeffi cients of heat transfer of the bundle have been calculated; they were values of 1.26 to 5.84 W/(m2 · o C) at the Reynolds numbers of (20–163)∙103
.
It has been found that pollution may lead to a substantial reduction in the transfer (up to 41%). The optimum
area of the outlet hole of the exhaust shaft increases as the exhaust-shaft height grows, but decreases with pollution
of the bundle.
Author:
G. S. Marshalova, A. B. Sukhotskii, D. V. Ostrovskaya, E. S. Danil′chik
Keywords:
air-cooled apparatus, pollution, enhanced free convection, exhaust shaft
Page:
46
ASSESSMENT OF THE BEHAVIOR OF FIRE-PROOF COATINGS IN THE TEMPERATURE FIELD FROM –162 TO +1300o C FORMED DURING ACCIDENTS INVOLVING LIQUEFIED NATURAL GAS
At present, in the Russian Federation, there is no unifi ed standard method of testing protective coatings for cryo- and fi re-resistance that would refl ect the specifi city of accidents involving liquefi ed natural gas (LNG). In the existing methods of testing for cryoresistance, use is made of harder conditions than in LNG action on an object with an applied protective coating, and fi re tests are carried out at a lower temperature than the temperature of combustion of LNG vapors under real conditions. A thermophysical calculation has been performed for a number of protective coatings applied on a steel plate under the action of the temperatures of –176 and 1100o
C in conditions of a
cryochamber and a furnace with respect to the criterion of the time of reaching brittleness and yield points.
Author:
P. S. Kopylov, S. N. Kopylov, I. P. Eltyshev, A. V. Pekhotikov
Keywords:
methane, liquefi ed natural gas, cryoprotection, fi re-resistance, heat and mass transfer
Page:
54
TWO-PHASE DEVICES FOR THERMAL REGULATION OF HEAT LOADED COMPONENTS OF ELECTRIC TRANSPORT
Ensuring optimum thermal regimes of operation of engines, electronics, accumulator batteries, and other electric
transport equipment is a problem of current importance. Granted the diversity of cooling systems of heat-releasing
objects, the use of heat pipes and thermosyphons is one optimum area. Heat pipes and thermosyphons are noiseless
in operation and do not require energy expenditures, which is very important for cordless electric transport. They
can receive heat from the object being cooled, remove it beyond the boundaries of the volume fi lled with equipment
and then transfer it to the cooling liquid or air. Using heat exchangers on heat pipes, it is possible not only to optimize heat regimes of the operation of an electric engine, batteries, power electronic equipment, but also to ensure
the work of onboard climate control systems.
Author:
L. L. Vasiliev, A. S. Zhuravlev, L. P. Grakovich, M. I. Rabetskii, and L. A. Dragun
Keywords:
electric vehicle, electric transport, thermal regulation, heat pipe, thermosyphon
Page:
62
SURROGATE MODELING TO OPTIMIZE THE WORKING PROCESS IN THE TURBINE STAGE
Based on the URANS approach, a numerical model has been developed for controlling temperature separation on
the working turbine blades of an aircraft engine and the effi ciency of its stage by adjusting the circumferential position of injectors at the combustion chamber outlet and adding a swirl of gas fl ow inside them. It has been shown
that in the absence of fl ow swirl in the interblade channel, adjusting the location of the heat spot relative to the
inlet to this channel exerts diff erently directed eff ects on the turbine effi ciency and temperature separation in it.
When the fl ow swirls in the heat spot, unidirectional improvement in the aerodynamic and thermal characteristics
of the turbine fl ow does not occur. In this case, the decrease of the turbine effi ciency (relative to the case of uniform
temperature fi elds and gas fl ow velocity) is in the range from 0.19 to 1.08%. A surrogate model based on the IOSO
software package is proposed, which is used to optimize the working process in the turbine stage of an aircraft engine
in a multicriteria formulation, which allows obtaining a specifi ed number of Pareto-optimal solutions for the turbine
effi ciency and temperature separation in it.
Author:
D. K. Popova, N. N. Kortikov
Keywords:
rotor–stator interaction, fl ow swirl, combustion chamber, temperature separation, clocking eff ect, turbine stage, IOSO technology, multicriteria optimization
Page:
73
CRYSTALLIZATION OF SMALL-SIZED PARTICLES
The problem of crystallization of a molten particle with an initial temperature equal to the melting point is investigated during convective heat exchange on the surface. The heat conduction equation is solved for a region with movable
interphase boundaries, the law of movement of which is not known in advance. For small-sized particles, analytical
expressions are obtained that describe the propagation of the crystallization front, and the crystallization time with
indication of applicability limits.
Author:
R. N. Rizakhanov
Keywords:
crystallization, crystallization front, interphase boundary, heat conduction equation, phase transition, convective heat exchange, temperature distribution, crystallization time
Page:
82
EXPERIMENTAL STUDY OF THERMAL CHARACTERISTICS OF THE COOLING TOWER SPRINKLER DRY BLOCK
In order to increase the energy effi ciency of the cooling tower and save water, a cooling tower sprinkler has been
developed consisting of a dry block — heat exchange tubes of the radiator and a wet block — contact elements in the
form of corrugated plates. A mathematical model is proposed for determining the thermal power of the cooling tower
dry block. Experimental studies of free-convective heat exchange of in-line bundles of copper tubes of the sprinkler
block 100 × 100 mm with a vertical air fl ow produced by a fan with an adjustable fl ow rate are presented. Data
on the eff ect of the average velocity of air passing through the sprinkler tube bundle on the change in the thermal
power of the cooling tower dry block are obtained. The experimental data are generalized by similarity equations for
calculating the average heat emission of bundles and their individual rows. It is proven that an increase in the mass
fl ow rate of liquid in the tubular radiator of the sprinkler dry block leads to a decrease in the total amount of heat removed in the cooling tower. It was found that an increase in the average air velocity in the sprinkler block leads to an
increase in the thermal power, as well as to a decrease in the proportion of heat exchange due to natural convection.
Author:
I. N. Madyshev, O. S. Dmitrieva
Keywords:
sprinkler, cooling tower, heat emission, tubular radiator, thermal power, Nusselt number
Page:
90
SOLUTION OF THE STEFAN PROBLEM FOR QUASI-STATIONARY FLUCTUATIONS OF AMBIENT TEMPERATURE
A solution to the Stefan problem for a one-dimensional layer of thermal phase-changing material insulation of the
walls of a room is proposed under the assumption that the temperature of the outer surface of the wall is equal
to the ambient temperature and its fl uctuations are harmonic and quasi-stationary. The indicated problem was
solved depending on the relative amplitude of fl uctuations of the ambient temperature Δϑ, the Biot number, which
characterizes heat emission from the room, and a set of physical properties of the thermal insulation material. An
analytical solution to the problem for relatively large amplitude of ambient temperature fl uctuations is observed — Δϑ ≥ 1. It is shown that in using a phase-change material with a phase transition temperature equal to the room
temperature, there are no fl uctuations of the temperature of the inner surface of the room wall, the temperature of
which is equal to the room temperature during the entire period of ambient temperature fl uctuations.
Author:
E. P. Valueva, E. A. Morozov
Keywords:
Stefan problem, phase-change materials, quasi-stationary regime
Page:
100
DETERMINATION OF STRESSES IN THE WALLS OF A SOLAR WATER HEATER CHANNEL DURING FREEZING OF WATER
The problem of modeling a fl at rectangular channel of a solar water heater fi lled with water during its freezing is
considered to estimate the stresses arising in the channel walls. A mathematical model of the deformation of the
wall of such a channel during partial freezing of water in it is developed. The theory of elastic cylindrical bending
of a two-layer plate is used for modeling. Calculation relationships are obtained for determining the stresses in the
channel walls depending on the thickness of the freezing ice. An example of calculating the stresses in the channel
walls during water freezing is given. Based on the calculation results, the stresses arising in the metal wall of the
solar water heater channel during water freezing are determined.
Author:
A. T. Teimurkhanov, G. N. Tovarnykh
Keywords:
solar water heater, fl at channel, water, ice, freezing, two-layer plate, bending, stress
Page:
109
EFFECT OF ROOM SIZE ON EXTERNAL EXPLOSION INDUCED BY VENTED NATURAL GAS EXPLOSION
The computational fl uid dynamics technology was used to study the infl uence of the equivalent length-to-diameter
(L/D) ratio of a room on the eff ects of natural gas explosions, and the distribution characteristics and scope of
infl uence of internal and external explosion overpressures and high temperatures were analyzed. The results
revealed that the internal maximum peak overpressure increased linearly with increase in the L/D ratio. As the L/D
ratio increased, the external explosion overpressure and safety distance of overpressure hazards fi rst increased and
then decreased, and the external explosion location gradually approached the vent. With increase in the L/D ratio,
the range of external combustible gas clouds expanded, whereas the range of high-temperature areas gradually
decreased. The range of external combustible gas clouds was negatively correlated with the range of the hightemperature areas. When the L/D ratio increased, the presence of large-scale obstacles reduced the growth rate of
the indoor and outdoor maximum peak overpressure, but increased the range of high-temperature areas.
Author:
Kai Yang, Hao Wu, Lei Pang, Pengfei Lv, Jing Shen
Keywords:
natural gas, vented explosion, room size, external explosion, hazard
Page:
115
COMPOSITE LIQUID FUELS: ENVIRONMENTAL, ENERGY, AND TECHNICAL-ECONOMIC ASPECTS
The results of experimental investigations into the main stages of the life cycle of composite liquid fuels are presented.
These fuels are synthesized with a view to solving a set of environmental, economic, energy, and technological
problems. The potential feedstock is formed from among industrial and municipal waste, plant components,
biomass, esters, fats, waste and industrial process waters. Considering their properties, composite liquid fuels can
be used in boiler, gas turbine, propulsion, and other installations. The results of multicriterial analysis of the main
environmental, energy, and technical-economic indicators of typical composite liquid fuels are presented. The most
promising compositions are identifi ed.
Author:
V. V. Dorokhov, D. S. Romanov,P. A. Strizhak
Keywords:
composite liquid fuels, additives, minimization of anthropogenic emissions, improvement of combustion effi ciency, waste thermal conversion
Page:
125
IGNITION OF HYDROGEN–AIR–WATER VAPOR LEAN MIXTURES BEHIND SHOCK WAVES
The ignition of lean mixtures of hydrogen with air and water vapor behind refl ected shock waves was studied experimentally in the temperature range 947–1552 K at a pressure of 1 atm. Numerical simulation of the concentration
profi les of the electron-excited OH*
radical using several widely employed detailed kinetic mechanisms is performed.
It is shown that the infl uence of water on the self-ignition of lean hydrogen–air mixtures at temperatures above
1050 K is insignifi cant. The discrepancy between the results of calculations and experimental data at temperatures
below 1050 K is explained by the presence of small impurities formed in catalytic reactions on the surface.
Author:
P. N. Krivosheyev, Yu. S. Kisel, A. V. Skilond′, K. P. Avsyukevich,a,b A. M. Tereza, O. G. Penyazkov
Keywords:
ignition delay, shock tube, shock wave, mixture of hydrogen with air and water vapor, detailed kinetic mechanism, chemical kinetics, numerical simulation
Page:
137
NUMERICAL STUDY OF THE INFLUENCE OF THE METHOD OF FEEDING OF REACTANTS TO THE REACTOR ON THE INTERACTION OF URANIUM HEXAFLUORIDE WITH METHANE AND OXYGEN IN A COMBUSTION REGIME
Results of numerical simulation of the infl uence of the method of feeding, by a coaxial injector, of reactants to a
reactor of the tunnel-burner type on the basic parameters of the process of interaction of uranium hexafl uoride with
methane and oxygen in the regime of diff usion turbulent combustion have been presented.
Author:
T. A. Fedorova, D. S. Pashkevich, P. A. Popov, V. A. Talalov
Keywords:
uranium hexafl uoride, hydrogen fl uoride, uranium dioxide, numerical simulation, diff usion turbulent combustion
Page:
144
OBTAINING HYDROGEN FLUORIDE DURING THE INTERACTION OF DEPLETED URANIUM HEXAFLUORIDE WITH METHANE AND OXYGEN IN A COMBUSTION REGIME
Computational and experimental studies have been made of obtaining hydrogen fl uoride from uranium hexafl uoride during its interaction with methane and oxygen in a combustion regime. The calculations have shown that in a thermodynamically equilibrium mixture in the system of elements U–F–C–H–O in which the number of hydrogen atoms is larger than or equal to the number of fl uoride atoms, and the number of oxygen atoms is twice as large as the number of uranium atoms, the fl uoride-containing substance at a temperature higher than 1100 K is hydrogen fl uoride, and the basic uranium-containing substances are uranium oxides. Uranium fl uorides and uranium oxyfl uorides amount to about 3% of the mixture, and there are no carbon fl uorides and oxyfl uorides in it. A required temperature of the mixture may be attained during the interaction of uranium hexafl uoride with methane and oxygen in a combustion regime. It has been established experimentally that in a reactor of the tunnel-burner type of diameter 142 mm in the UF6–CH4–O2 mixture with a nearly 1.0:1.5:2.5 mole ratio of the substances, the fl ame is reliably formed using the self-igniting F2–NH3 pair and is stably burning at a rate of fl ow of uranium hexafl uoride of the order of units of grams a second. The basic uranium-containing product of the process of combustion is a mixture of uranium oxides UO2 and U3O8, in which covalent-bonded fl uorine is present in the amount of about 1% mainly in the form of UF4,
and the basic fl uorine-containing product is hydrofl uoric acid with a content of hydrogen fl uoride higher than 95%.
Author:
D. S. Pashkevich, A. R. Zimin, Yu. I. Alekseev, D. A. Mukhortov, P. S. Kambur, V. B. Petrov, D. A. Bazhenov,d,e V. V. Kapustin, P. A. Smolkin, T. A. Fedorova
Keywords:
depleted uranium hexafl uoride, hydrogen fl uoride, uranium dioxide, methane, combustion
Page:
153
MULTICRITERIA ANALYSIS OF THE CHARACTERISTICS OF BIOFUEL FABRICATED IN A NANOMEMBRANE REACTOR
Characteristics of biofuel produced via environmentally safe transesterifi cation and nanofi ltration in a nanomembrane
reactor are presented. A porous nanomembrane has been fabricated on the basis of polyvinylidenfl uoride and
vinylidenfl uoride–tetrafl uoroethylene copolymer. The operational characteristics of the obtained fuel have been
investigated using a stand based on a swirl burner reproducing the work of a small power diesel generator. The
results of investigating the properties of diesel fuel-based biofuel compositions and also the characteristics of their
spray, ignition, and combustion have made it possible to identify the optimum concentration of fatty acid methyl
ethers of rapeseed oil part as of such a composition
Author:
A. E. Ashikhmin, M. V. Piskunov, and P. A. Strizhak
Keywords:
liquid fuel, biodiesel, nanomembrane, transesterifi cation, spray, combustion, fl ue gases
Page:
162
INVESTIGATION OF THE HYDRODYNAMIC STRUCTURE OF A DETACHED TWO-PHASE BUBBLE FLOW AND THE HEAT EXCHANGE IN A RECTANGULAR CHANNEL WITH AN OBSTACLE
An experimental investigation of the hydrodynamic structure of a detached two-phase bubble fl ow and the heat exchange in a channel with an obstacle in the form of a rectangle, an isosceles trapezoid, or a rectangular trapezoid
has been performed. The experiments were carried out for the fl ow of a liquid and with a gas content β = 0–5% at
Reynolds numbers falling within the range 5000–12,500. The total hydrodynamic characteristics of this fl ow were
measured by the PIV/PLIF method. It is shown that the introduction of bubbles into a liquid fl ow in the indicated
channel shifts the points of its reattachment upstream, as compared to that of the one-phase fl ow, which is due to the
increase in the velocity gradient of the two-phase liquid fl ow in the near-wall region of the channel. For estimating
the heat exchange in the channel, the temperature of the outer wall of a heated stainless-steel plate mounted fl ush
with the channel wall, was measured with the use of an infrared imager. It was established that the combined eff ect
of the introduction of an obstacle into the channel and of bubbles into the liquid fl owing in it makes it possible to
intensify the heat exchange in the channel by 60%.
Author:
I. A. Evdokimenko, P. D. Lobanov, A. V. Chinak, K. A. Filippskii, E.-K. Si-Ahmed, C. Gentric, W. Blel, J. Legrand
Keywords:
two-phase fl ow, bubbles, detached fl ow, heat exchange, obstacle
Page:
173
MATHEMATICAL MODELING OF THE PROCESS OF CONVECTIVE DRYING OF COTTON FABRIC
The results of modeling convective drying of cotton fabric are presented. The mathematical model takes into
account various mechanisms of water transfer in a capillary-porous body and allows obtaining local values of
thermophysical and textural parameters of the material. It is shown that the results of numerical modeling are in
satisfactory agreement with experimental data
Author:
O. R. Dornyak, M. K. Kosheleva, and V. P. Meshalkin
Keywords:
drying, fabric, mathematical modeling, heat and mass transfer, multiphase systems
Page:
183
REVEALING THE CONDITIONS FOR THE FORMATION OF PRESSURE PEAKS IN THE PROBING PULSE
The possibility is shown of using pressure pulses rerefl ected from the surface of a porous medium in a shock tube
and from its upper end face as probing pulses for studying changes occurring in the medium under the infl uence of
a shock wave.
Author:
A. T. Akhmetov, I. K. Gimaltdinov, A. F. Mukhametzyanov
Keywords:
sand fi ll, pressure pulse, shock tube, probing pulse, pressure peak
Page:
190
SIMULATION EXPERIMENTS ON LMS-1D REGOLITH PARTICLES PRECIPITATION IN A GYROTRONIC DISCHARGE AND THEIR IMPACT ON SOLAR PANELS OF SPACE VEHICLES
A description is given of simulation experiments of the interaction of lunar dust with the surface of solar panels.
The experiments are based on the creation of a dust plasma cloud by exposure of a substance simulating lunar dust
to the radiation from a powerful pulse gyrotron. This approach has been tested using a lunar regolith simulant. An
analysis is presented of the results of precipitation of charged regolith particles on solar panels of various types and
variation in their effi ciency
Author:
A. S. Sokolov, V. D. Stepakhin, N. N. Skvortsova, V. D. Borzosekov, T. É. Gayanova, A. K. Kozak, N. T. Vagapova, I. V. Badurin, E. S. Loginov E. A. Obraztsova, L. V. Kolik, A. S. Kon′kova, E. M. Konchekov, N. G. Gusein-Zade
Keywords:
: low-temperature plasma, dust plasma, regolith, gyrotron, microwave discharge, solar batteries
Page:
197
INTERACTION OF THE PLASMA CHANNEL OF A SPARK DISCHARGE WITH A SUSPENDED WATER DROPLET
An analysis of the interaction of the plasma channel of a spark discharge with a distilled-water droplet, suspended on a thread, under the conditions of its heating to 40oC is presented. The process of evaporation of such a droplet
with the participation of a thermionic-emission source without and with a spark discharge was considered. With the
use of pyrometry instruments, the dynamics of change in the temperature of water droplets in the process of their
evaporation was investigated. A qualitative investigation of the kinetics of evaporation of a suspended distilledwater droplet under experimental conditions has been performed. For the visual representation of the process of
evaporation of a spherical water droplet, over which the plasma channel of a spark discharge in the form of a plasma
fi lament fl ows, the notion of the peach eff ect was introduced. It was established experimentally that, independently
of the temperature of a water droplet, a spark discharge increases the rate of its evaporation by 35% supposedly
due to the expansion of the spark channel because of the radial fl ying-off of gas (environmental) molecules and the
additional heating of the water droplet along the meridian line.
Author:
I. A. Shorstkii
Keywords:
spark discharge, water droplet, evaporation, spark channel, heat and mass transfer, shock wave
Page:
206
NUMERICAL SIMULATION OF THE NONLINEAR STAGE OF LAMINAR-TURBULENT TRANSITION IN A SUPERSONIC BOUNDARY LAYER IN THE PRESENCE OF ACOUSTIC DISTURBANCES
Consideration is given to the excitation and development of the fi rst mode of instability on a plate at the free-stream Mach number M = 3, a nearly adiabatic wall temperature, and the Reynolds number Re∞ = 2∙107 . Based on direct numerical simulation, the authors have obtained the values of receptivity coeffi cients and critical amplitudes of the longitudinal component of pulsations of the fl ow-velocity vector in a supersonic boundary layer on a fl at plate at angles of attack of 0 and 5o
.
Author:
I. V. Egorov, N. V. Palchekovskaya
Keywords:
laminar-turbulent transition, nonlinear stage, supersonic fl ow, direct numerical simulation
Page:
215
EXPERIMENTAL INVESTIGATIONS OF THE STABLE FORM OF THE VORTEX STRUCTURE OF A SWIRLING FLOW
Experimental investigations on detection of the physical mechanisms and factors, responsible for the structurally
similar forms of spiral-vortex motion of fl uid media, have been performed. A confi rmation of the theoretical
dependence, defi ning the relation between the geometric sizes of three-dimensional spiral-vortex formations and the
frequencies of vortex motion in them, has been obtained. By the example of an impact swirling fl ow, it is shown that
a determinate large-scale vortex structure of a fl uid medium is formed as a result of the crisis of the thermodynamic
stability of the medium, corresponding to the phenomenon of crisis of a swirling fl ow
Author:
O. V. Mitrofanova, I. G. Pozdeeva, N. A. Starovoitov
Keywords:
aerohydrodynamics, swirling fl ow, spiral-vortex structures, swirling-fl ow crisis, thermodynamic stability, structural similarity, experimental investigations, acoustic vibrations, resonance
Page:
219
INFLUENCE OF THE PRANDTL NUMBER ON HEAT TRANSFER INTENSIFICATION IN A DEVELOPED TURBULENT FLOW IN A CHANNEL WITH ONE FINNED WALL
The paper presents the results of numerical modeling of a developed, spatially periodic turbulent fl ow and heat exchange in a rectangular channel (W/H = 1.5), on a wall of which of width W square cross-section fi ns with a side e = 0.1H are located with a pitch P = H, inclined relative to the channel axis by 45o. The fl ows of incompressible
media are considered at Prandtl numbers equal to 0.01, 0.7 and 10, and Reynolds numbers in the range 104
–106
.
The mathematical model of the fl ow is based on the RANS method and the equations of k–ω SST turbulence model.
An analysis of heat emission intensifi cation and of increase in the hydraulic resistance compared to fl ow in a smooth
channel is performed. Dimensionless dependences for integral characteristics of heat emission are obtained.
Author:
A. M. Levchenya, S. A. Galaev, V. V. Ris
Keywords:
fi nned channel, turbulent mode, spatially periodic fl ow, developed heat exchange, Prandtl number, numerical modeling
Page:
230
FORMATION OF THE SECONDARY VORTICES IN AN ANNULAR CHANNEL WITH IMMOVABLE SURFACES IN THE CASE OF SWIRLING OF FLUID FLOW IN IT
The appearance of the secondary vortices in an annular channel, formed by two immovable coaxial cylinders, in the
case of initial swirling of a fl uid fl ow in it, was considered. The fl uid fl ow was swirled with the use of an axial-vane
swirler with 22 aerodynamic vanes equipped with an indexing mechanism regulating the angle of swirl of the fl uid
fl ow. The aerodynamic characteristics of this fl ow were measured by the method of Doppler laser anemometry. The
calculations were performed using a numerical model, based on the fi nite volume method, which was verifi ed with
the use of experimental data. The formation of the secondary vortices in a swirling fl ow in the indicated channel was
visualized, and the main parameters of these vortices were determined. Prospects for the use of the secondary fl ows
arising as a result of the swirling of a fl uid fl ow in an annular channel for the intensifi cation of heat exchange in it
are shown.
Author:
E. V. Pankratov
Keywords:
intensifi cation of heat exchange, annular channels, secondary fl ows, Couette–Taylor fl ow, swirling fl ow, experimental investigation, numerical simulation
Page:
240
THERMAL CONDUCTIVITY OF AN ELECTRORHEOLOGICAL FLUID UPON THE CHANGE IN EXTERNAL ELECTRIC AND TEMPERATURE FIELDS
A study has been made of the rheological behavior of electrorheological fl uids containing composite perovskite-like-structured oxides under the impact of a constant electric fi eld of strength 0–4 kV/mm and elevated temperatures (20–60o
C). The behavior of the thermal conductivity of electrorheological fl uids has been analyzed upon the change in the temperature in the range 20–40o
C, and in the electric fi eld, from 0 to 1.5 kV/mm. Methods
of scientifi c experiment, the method of an unbounded plane layer, and regression-analysis methods were employed.
Experimental results have been interpreted in diagrammatic representation and analytical form.
Author:
I. M. Kharlamova, E. V. Korobko, L. V. Markova
Keywords:
thermal conductivity, composite perovskite-like oxides, electrorheological fl uid, experiment, modeling
Page:
250
THERMAL RELAXATION AND HEAT CONDUCTION OF A SOLID BODY
An analysis has been made of modern models of heat transfer in a solid body on the basis of the results of measurements
of the thermal-conductivity coeffi cient of a neodymium magnet. An agreement between the electron-photon heattransfer model and the experimental data has been shown. The results of investigations into the thermal conductivity
of a neodymium magnet with a varying orientation of magnetic force lines with respect to the direction of the heat fl ux
and several values of magnetic induction have been given. Assumptions have been made of the infl uence of internalenergy carriers, i.e., free electrons and photons radiated by the orbital electrons of atoms at the lattice sites of a body,
on the phenomena of thermal relaxation and thermal damping in the process of heat transfer
Author:
Yu. A. Kirsanov
Keywords:
heat conduction, anisotropy, thermal relaxation, thermal damping, magnetic fi eld, free electrons, orbital electrons, photons
Page:
256
THERMOPHYSICAL CHARACTERIZATION OF COMPOSITE MATERIALS BASED ON MOROCCAN DATE PALM FIBERS WITH HOT WIRE AND HOT PLANE METHODS
Composite materials based on mortar reinforced with plant waste as a building material are attracting an increasing
interest due to their many advantages including their thermal insulation capacity. In this work, the thermophysical
characterization of mortar reinforced with Moroccan date palm fi bers (DPF) was done using the hot wire and hot
plane methods (FP2C) which measure the thermal conductivity and thermal eff usivity, respectively. The experimental
results show that the inclusion of this type of fi ber in the mortar increases the thermal insulation capacity (by
decreasing the thermal conductivity) and the capacity to absorb/release heat at its surface (by decreasing the
thermal eff usivity). Also, DPFs lighten the mortar by decreasing its bulk density by up to 33%, and they decrease
the volumetric thermal capacity by up to 51% and the thermal diff usivity by up to 44%. The results of the thermal
conductivity of these composites were compared with those obtained by the box method (Cell EI700) and were also
compared with those predicted by theoretical models available in the literature.
Author:
M. Boumhaout, L. Boukhattem, and H. Hamdi
Keywords:
building, composite, conductivity, eff usivity, methods, theoretical models
Page:
264
THERMOPHYSICAL CHARACTERIZATION OF COMPOSITE MATERIALS BASED ON MOROCCAN DATE PALM FIBERS WITH HOT WIRE AND HOT PLANE METHODS
Composite materials based on mortar reinforced with plant waste as a building material are attracting an increasing
interest due to their many advantages including their thermal insulation capacity. In this work, the thermophysical
characterization of mortar reinforced with Moroccan date palm fi bers (DPF) was done using the hot wire and hot
plane methods (FP2C) which measure the thermal conductivity and thermal eff usivity, respectively. The experimental
results show that the inclusion of this type of fi ber in the mortar increases the thermal insulation capacity (by
decreasing the thermal conductivity) and the capacity to absorb/release heat at its surface (by decreasing the
thermal eff usivity). Also, DPFs lighten the mortar by decreasing its bulk density by up to 33%, and they decrease
the volumetric thermal capacity by up to 51% and the thermal diff usivity by up to 44%. The results of the thermal
conductivity of these composites were compared with those obtained by the box method (Cell EI700) and were also
compared with those predicted by theoretical models available in the literature.
Author:
M. Boumhaout, L. Boukhattem, and H. Hamdia
Keywords:
building, composite, conductivity, eff usivity, methods, theoretical models
Page:
264
CONVECTIVE HEAT TRANSFER IN LARGE-SCALE NATURAL SYSTEMS
In the work, the authors have presented an overview of the state of the art of modeling of large-scale atmospheric fl ows
and results of the cycle of investigations in this area that were carried out at the Institute of Continuum Mechanics
of the Ural Branch of the Russian Academy of Sciences. Using the laboratory analog of a tropical cyclone as an
example, a number of issues concerning the development and stability of tropical cyclones have been considered. The
authors have presented a novel laboratory model of general circulation of the atmosphere and results of modeling of
the warming in the Arctic. It has been shown that the loss of ice may cause the average temperature in a polar region
and in the mid-latitude region to substantially change.
Author:
A. N. Sukhanovskii, A. Yu. Vasiliev, A. A. Gavrilov, A. V. Evgrafova, E. N. Popova
Keywords:
heat transfer, laboratory modeling, analog of a tropical cyclone, general circulation of the atmosphere, numerical modeling
Page:
274