Volume 95, №4
METHOD FOR CONTROL OF THE VORTEX FLOW INTENSITY BY CHANGING THE BOTTOM POSITION IN A DC ARC FURNACE WITH A BOTTOM ELECTRODE
This paper describes methods and approaches for numerical simulation of liquid metal fl ows in a direct current
(DC) arc furnace with a bottom electrode. The model for numerical simulation takes into account an actual bottomelectrode arc furnace and is based on magnetohydrodynamic equations. The distributions of the Lorentz force,
temperature, and the vortex fl ow velocity are presented. The method to control and reduce the vortex fl ow intensity in
a liquid metal volume by changing the furnace bottom position is worked up. The results of the numerical simulation
show a possibility to reduce a negative infl uence of the vortex fl ow of a liquid metal up to 50%.
Author:
O. V. Kazak
Keywords:
DC arc furnace, electrovortex fl ow, convection, numerical simulation, bottom electrode
Page:
1002
WATER–STEAM ELECTRIC-ARC PLASMATRON
A structure of a linear-circuit d.c. electric-arc plasmatron with gas-vortex arc stabilization has been developed. Air or
steam can be used as a plasma-forming gas. The operation of the plasmatron requires no any other protective gases.
The plasmatron′s power is controlled within the limits of 30–60 kW. To ensure stable operation of the plasmatron, a
steam-generator structure has been developed that implements the idea of steam generation through the throttling
of water superheated under high pressure. This structure makes it possible to quite accurately control the steam fl ow
rate and temperature.
Author:
G. V. Dolgolenko , N. M. Kurbanov , A. S. Olenovich , V. S. Skavysh , I. V. Khvedchin , V. V. Savchin
Keywords:
plasmatron, water-steam plasma, tubular steam generator
Page:
1011
INVESTIGATION OF THERMOPHYSICAL PROPERTIES OF GRADIENT MATERIALS BY THE METHOD OF INVERSE PROBLEMS
Methods have been proposed for computational-experimental determination of thermophysical characteristics
of gradient materials whose functional properties change systematically as a function of spatial coordinates. An
algorithm has been proposed for calculating thermophysical characteristics of gradient materials, whose properties
change in one direction. Experimental investigations have been conducted into specimens of Cerablanket fi brous
industrial material made up of layers of various density
Author:
O. M. Alifanov , S. A. Budnik , A. V. Nenarokomov , A. V. Netelev , A. S. Okhapkin , V. A. Chumakov
Keywords:
gradient materials, thermophysical characteristics, iterative regularization method, thermovacuum stand
Page:
1015
INVESTIGATION OF HEAT TRANSFER OF BULK AND THIN-FILM PbInTe SAMPLES BY THE METHOD OF DYNAMIC GRATINGS
Measurements of the thermal diff usivity of thin and bulk indium-doped lead telluride have been taken using a modifi ed method of dynamic gratings. Thermal gratings were recorded by a 20 ns pulsed laser radiation at a wave length of 532 nm. Dynamic gratings were recorded by a 635 nm continuous laser radiation. The analysis of the diff raction signal kinetics made it possible to determine the life-time of thermal gratings recorded in the investigated samples. It is shown that the use of an additional homodyne fi eld coherent with respect to the diff raction signal fi eld makes it possible to enhance and fi lter off the selected information component. Based on registered kinetic dependences of the diff racted signal intensity, the thermal diff usivity of bulk and thin fi lm indium-doped lead telluride samples was determined. It has been established that for a micron-thick fi lm, the thermal diff usivity is ten percent lower than for a bulk sample. An investigation has been made into the dependence of the heat transfer in the said samples on their temperature and it has been shown that the rise in the samples′ temperature in the range from 40 to 95oC results in
a 20-percent decrease of their thermal diff usivity
Author:
E. V. Ivakin , A. L. Tolstik , D. V. Gorbach , A. A. Stankevich
Keywords:
thermoelectric material, lead telluride, heat transfer, thermal conductivity, thermal diff usivity, phase selection, thermal response
Page:
1026
NONISOTHERMAL CHANNEL FLOW OF A NON-NEWTONIAN FLUID UNDER THE CONDITIONS OF CHEMICAL TRANSFORMATIONS
The processes of hydrodynamics and heat transfer during the fl ow of a non-Newtonian polymeric medium in a plane
channel have been investigated with boundary conditions of the fi rst kind. Consideration was given to a steady-state
nonisothermal process with low values of the Reynolds number and high values of the Péclet number, which made
it possible to neglect gravity and inertial forces, and also longitudinal thermal conductivity. The Ellis model with a
viscosity dependent on temperature, pressure, and the degree of chemical transformation was used as the rheological
model. A high-viscosity medium was investigated. Therefore, it is the dissipative term that was taken account of
in the energy equation. With the above rheological model, an expression in explicit form was obtained from the
equation of motion of such a medium for the velocity profi le of its fl ow. It has been established that the dependence
of the viscosity of a medium on its temperature, pressure, and the degree of transformation has an appreciable eff ect
on the distribution of the temperature of the medium and the velocity of its fl ow along the channel′s length. Taking
account of the temperature dependence of the viscosity of the medium leads to a decline in the role of dissipation in
the process of its warmup. The dependence of the medium′s viscosity on pressure, conversely, considerably enhances
the dissipative eff ect, which appreciably accelerates the course of a chemical reaction.
Author:
A. V. Baranov
Keywords:
non-Newtonian fl uid, heat transfer, nonisothermal fl ow, dissipation
Page:
1031
OUTFLOW OF A BOILING LIQUID FROM A TUBULAR CHANNEL UNDER THE ACTION OF A HYDRAULIC FRICTION FORCE
The emptying of a tubular channel as a result of the outfl ow of a boiling liquid from its one end subjected to a sudden
seal failure was investigated. The case where the liquid outfl ows from the channel in the sluggish regime in which
the lag eff orts are insignifi cant and, consequently, the rate of emptying of the channel is mainly determined by the
hydraulic losses and the eff ects of adiabatic expansion of the boiling liquid was considered. It is shown that the
system of equations defi ning the outfl ow of the liquid from the channel in the two limiting cases where the hydraulic
friction force acting on the liquid fl ow in the channel changes linearly with change in the fl ow velocity and where this
force changes by the square law can be reduced to one nonlinear equation. Self-similar solutions of the problem on
the sudden loss of the sealing at one end of the channel have been constructed.
Author:
F. R. Khuzina , A. A. Rusinov , M. S. Salieva , V. A. Krasil′nikov , A. R. Nabiullin
Keywords:
boiling liquid, self-similar solutions, hydraulic friction.
Page:
1037
PARALLEL IMPLEMENTATION OF THE HYBRID LATTICE BOLTZMANN METHOD ON GRAPHICS ACCELERATORS
An analysis has been conducted for the computational performance of a hybrid mathematical model for investigating the laws of thermogravitational fl ows. Hydrodynamic processes were calculated using mesoscopic lattice Boltzmann equations, and thermodynamic processes were described on the basis of a fi nite-diff erence solution of a macroscopic energy equation. It has been established that scheme D3Q19 and D3Q27-based hybrid mesomacroscopic models reproduce identical fi elds of thermohydrodynamic characteristics. In this case, the velocity of calculating nineteenand twenty seven-velocity topologies diff ers insignifi cantly at a grid density lower than 2013
. Subsequently, the
superiority of model D3Q19 over model D3Q27 in terms of computational performance.
Author:
A. É. Nee
Keywords:
hybrid lattice Boltzmann method, graphics accelerator, fi nite-diff erence method, natural convection.
Page:
1044
TOWARD THE TEMPERATURE DEPENDENCE OF THE YOUNG MODULUS OF MAGNETIC MATERIALS
Using the example of a ferromagnetic dielectric, an algorithm is proposed for calculating the Young modulus of
elastically deformable solid bodies on the basis of the Holstein–Primakov transformations and the theory of spin
waves. Due to the method of averaging over the ground state of a magnetic, a general expression is obtained for the
temperature dependence of the Young modulus in a wide temperature range.
Author:
S. O. Gladkov , É. M. Kartashov
Keywords:
Young modulus, compressibility factor, temperature, shear modulus magnons, equilibrium distribution function, exchange interaction
Page:
1051
DEVELOPMENT OF AN INNOVATIVE METHOD FOR INCREASING OIL RECOVERY OF CLAY LAYERS
Consideration has been given to intensifying the process of oil production using a new innovative method of enhancing oil recovery of mudded-off formations in Azerbaijan whose purpose is a reduction and sometimes full prevention
of the phenomenon of swelling of clay fractions contained in the composition of oil reservoirs in the process of
implementing local fl ooding. In laboratory investigations, electrochemically treated water, catholyte, was used as a
displacing fl uid. It was established that the curves constructed for formation waters treated with alkaline solution
(i.e., chemically) and catholyte (i.e., electrochemically) are similar, which confi rms yet another time that they create
an identical alkaline medium. In both cases, due to the rise in the pH value, we observed a signifi cant drop in the
interfacial tension on the "water–oil" contact line. However, the tension occurring on the contact boundary of the
considered "activated water–oil" pair decreases faster with respect to the interfacial tension formed between oil and
chemically treated water. The analysis of the dynamics of the increase in the recovery factor in the reservoir model
after exposure to chemically and electrochemically treated water has shown that when the reservoir is exposed to
catholyte, this indicator rises much faster.
A study has been made of the infl uence of the reservoir model of electrochemically treated water on oil
permeability. As a result of a more favorable dispergation of activated water into oil as an emulsifi er, an indirect
confi rmation of the appearance of an emulsion in reservoir conditions was obtained. The existence of this fact massively increases the likehood of an emulsion appearing in reservoir conditions and enhances the range of emulsions
emerging as a slug in the process of displacing reservoir fl uids. Thus, the injection of the proposed electrochemically
activated fl uid into the formation with a view to maintaining formation pressure and reducing the swelling factors of
formation rocks is real and expedient.
Author:
N. M. Safarov
Keywords:
intensifi cation of production, reagent-free method, electrochemical activation of water, potential determining ions, clay minerals, swelling, increasing the oil recovery factor, possibility of emulsion occurrence in a formation
Page:
1056
KARMAN–POHLHAUSEN METHOD: CRITICAL ANALYSIS AND NEW SOLUTIONS FOR THE BOUNDARY LAYER ON A PLANE PLATE
A generalized critical analysis of the main known polynomial solutions obtained for the velocity profi le of the fl uid
fl ow in the laminar boundary layer on a plane plate with the use of the integral Karman–Pohlhausen method has been
performed. The main reasons for the low accuracy of these solutions were revealed and ways of its increasing were
determined. Effi cient schemes of calculating the parameters of the indicated boundary layer with minimum errors,
in particular, a new trinomial polynomial, defi ning the velocity profi le of the fl uid fl ow in this layer, are proposed.
A new solution of the problem on the boundary layer fl ow over a plane plate in the form of the fourth-degree
(Sutton) polynomial gives an almost exact value of the friction stress of this fl ow with small errors in determining its
displacement thickness (0.12%) and shape parameter (0.12%), and an analogous solution in the form of the seventhdegree (Mughal) polynomial provides a very high accuracy of approximation of the friction stress of the indicated
fl ow with an almost zero error at negligible small errors in calculating its displacement thickness (0.04%) and shape
parameter (0.03%) of this layer.
Author:
V. A. Kot
Keywords:
Karman–Pohlhausen method, boundary layer, Blasius equation, fl uid fl ow, plane plate, polynomial solutions, integral methods
Page:
1063
MEMBRANE-AREA DISTRIBUTION AND ORDER OF SEPARATION OF MULTICOMPONENT MIXTURES IN BAROMEMBRANE SYSTEMS
The problem on separation of a multicomponent mixture in a baromembrane system was considered. An optimum
contact-area distribution at each stage of the separation process was found. The lowest power consumption
corresponding to this distribution was estimated for the case were individual components or fractions of a mixture
are separated sequentially and for the case where the mixture is divided at the fi rst separation stage into the fl ows
consisting of several components or fractions. The irreversible power consumptions in the separation processes
realized by the indicated methods were compared.
Author:
A. M. Tsirlin , L. G. Gagarina
Keywords:
baromembrane system, multicomponent mixture, irreversibility, entropy production, chemical potentials, separation order
Page:
847
DYNAMICS OF STONELEY WAVES AT THE "WATER–WATER-SATURATED OR GAS HYDRATE-SATURATED SAND" INTERFACE
The process of propagation of the Stoneley wave at the "water–water saturated or gas hydrate-saturated sand" interface is considered. To describe the process, the equations of continuity, state of the liquid, of momenta, wave equations, equations for the displacement of particles and components of stress tensors are used. As a result of fi nding analytical solutions in the form of a harmonic traveling wave for pressure, displacements, potentials for the vectors of longitudinal and transverse waves, a dispersion equation was obtained for determining the Stoneley wave velocity.
The values of Stoneley wave velocity are obtained for diff erent saturations of sand with water and gas hydrate.
The dependence of the depth of penetration of a sound wave, of longitudinal and transverse waves into a liquid and
a solid medium on frequency is determined. The idea of determining the thickness of the hydrate-bearing layer by the
degeneration of the Stoneley wave with an increase in the duration of the latter is proposed.
Author:
V. Sh. Shagapov , G. R. Rafikova , G. R. Karimova
Keywords:
longitudinal waves, transverse waves, Stoneley wave, sand, gas hydrate, water saturation, hydrate saturation
Page:
853
MODELING AND INVESTIGATION OF NONSTATIONARY PRESSURE AND TEMPERATURE FIELDS IN A DEFORMABLE FORMATION DURING THE FILTRATION OF A GAS–CONDENSATE MIXTURE
A procedure and an algorithm have been proposed that allow modeling the problem of identifi cation of parameters
of a deformable formation during the fi ltration of a gas–condensate mixture in a gas regime with account taken of
the change in the temperature fi eld. In fi nding the parameters involved in the permeability and porosity functions, the
author takes minimization of the functional of the quadratic error of calculated and actual pressures at the wellbore
as the optimization criterion
Author:
B. Kh. Feizullaev
Keywords:
modeling, fi ltration, identifi cation, pressure, porosity, permeability, saturation, gas–condensate mixture
Page:
860
SPATIAL-TEMPORAL DISTRIBUTIONS OF THE PRESSURE IN A BED WITH A WELL IN DIFFERENT REGIMES OF PRODUCTION OF A FLUID FROM THE WELL
The problem on the nonstationary pressure fi eld formed in a fi lter bed with a well in the regimes of start of a pump
used in the production of a fl uid from the well, continuous work of the pump with a variable productive rate, and
subsequent stop of the pump was solved with regard for the mass balance of the fl uid fl owing from the bed into the
well, the fl uid produced from the well, and the fl uid used to change the fl uid level in the annulus of the well. Results
of computational experiments on determination of the spatial-temporal pressure distributions in the bed and in the
well in diff erent regimes of production of the fl uid from the well are discussed. The main factors determining the
spatial-temporal distributions of the pressure in the bed after the pumping of the fl uid from the well begins and
after it is terminated were found. The infl uence of the collector characteristics of the bed, the viscosity of the fl uid
saturating it, and the rate of pumping of the fl uid from the well on the formation of pressure fi elds in the bed and in
the well, the duration of the periods of relaxation and stabilization of the pressure fi eld in the bed, and the dynamics
of its transformation into the steady state at diff erent stages of production of the fl uid from the well was determined.
Author:
A. I. Filippov , O. V. Akhmetova , A. A. Koval′skii , M. A. Zelenova , N. A. Unchshikov
Keywords:
fi ltration, productive rate, well, pump, exact solution, Laplace–Carson integral transform, computational experiment
Page:
867
SIMULATION OF GAS MOTION IN A RESERVOIR–PIPELINE SYSTEM
A model has been constructed for the process of unsteady-state gas motion in a reservoir–pipeline system. A
boundary-problem of unsteady-state gas motion in a reservoir–pipeline system has been solved with account for the
law of pressure change at the pipeline outlet. Pressures have been determined at the well mouth and well bottom.
Analytical expressions have been obtained that make it possible to identify a change in the volume of gas production
per unit of time in simultaneous connection to and gas takeoff from a transition pipeline during the motion of gases
in a reservoir–pipeline system
Author:
É. M. Abbasov , N. A. Agaeva
Keywords:
gas fi ltration, pressure, Laplace transition, diff erential equation
Page:
878
FILTRATION WAVES
Equations and relations have been obtained for describing one-dimensional fi ltration waves in a homogeneous
isotropic porous medium in plane, radial, and spherical cases. To this end, use was made of the equation of motion
of a liquid phase with account taken of frictional forces, which in the case of stationary fi ltration with parallel
streamlines coincides with Darcy′s fi ltration law. The equations of motion and continuity reduced to an equation of
telegraphy permitted constructing relations for the wave number, the absorption coeffi cient, and the damping factor,
and also for the velocity of fi ltration waves. The developed theory of fi ltration-wave pressure fi elds refi nes the ideas
of propagation of fi ltration wave perturbations in a porous medium. It has been shown that the obtained expressions
for the wave fi eld in a wave approximation when the wave velocity tends to infi nity are consistent with the existing
solutions of the piezoconductivity equation
Author:
A. I. Filippov , O. V. Akhmetova
Keywords:
porous medium, fi ltration waves, damping factor, piezoconductivity coeffi cient.
Page:
889
MATHEMATICAL SIMULATION OF DISSOLUTION OF ROCKS IN THE COURSE OF KARSTING PROCESSES
A mathematical model of dissolution of rocks has been developed with regard for the specifi cs of the dissolution
processes in the porous space of rocks. The factors determined by this specifi city have been revealed. The infl uence
of the capacitive properties of rocks changing in the course of the dissolution process has been studied. An analytical
solution of the karst problem is constructed. An expression is obtained for the rate of the progress of the karsting
process.
Author:
M. G. Khramchenkov
Keywords:
karst, dissolution of rocks, karsting of rocks
Page:
896
PNEUMATIC SEPARATION OF FRACTIONS OF A POLYDISPERSE GAS SUSPENSION IN A LOW-VELOCITY FLOW
The authors have described a change in the spatial dispersity distribution of a powder gas suspension on a z-shaped
classifi er of particles. The process of separation of particles by size occurs under the gravity force and the aerodynamic resistance force and is described by the Eulerian model of a polydisperse gas suspension consisting of several
fractions of particles of varying radius and of air as the carrier medium. The dynamics of dispersed fractions is
described by systems of equations of the gasdynamic type with account of the interphase exchange of momentum
and energy with the carrier medium whose motion is described by a system of Navier–Stokes equations which
takes account of the exchange of momentum and energy with the dispersed fractions. The system of equations of
a polydisperse gas suspension is represented in generalized curvilinear coordinates and is solved by the explicit
predictor–corrector method with splitting of the spatial operator by directions and with the scheme of nonlinear
correction at each time step. Consideration has been given to the time and space characteristics of the process of
motion of the carrier medium and the dispersed fractions
Author:
A. L. Tukmakov , V. V. Khar'kov , A. A. Akhunov
Keywords:
polydisperse gas suspension, Navier–Stokes equations, explicit McCormack scheme, classifier of fractions
Page:
902
IDENTIFICATION OF REGIMES AND CONDITIONS FOR MOISTURE, REMOVAL FROM MATERIALS BY NONCONTACT EXPOSURE TO ULTRASONIC VIBRATIONS
The possibility of intensifying the drying of materials by noncontact ultrasonic action at a frequency of 22 kHz at
sound pressure levels up to 175 dB has been studied. A signifi cant increase in the rate of drying materials in the range
of sound pressure levels from 160 to 165 dB was revealed, which is due to the implementation of the mechanisms of
moisture removal from a dried material without a phase transition, i.e., due to the dispersion of free moisture from
the surface of the material by ultrasonic vibrations. In this case, the time of drying the material is reduced by more
than 40% compared with its drying by a conventional dryer, with an ultrasonic device consuming no more than 25%
of the electric power of a conventional dryer required for drying a material weighing 0.25 kg. Further acceleration
of the process is not always advisable, since the reduction of the time of drying the material by 57.1% on exposure to
a sound pressure of 175 dB requires more than three times increase in energy consumption (82% of the total electric
power of the dryer) for creating ultrasonic vibrations
Author:
A. V. Shalunov , V. N. Khmelev , S. A. Terent′ev , V. A. Nesterov
Keywords:
drying, dehydration, ultrasound, sound pressure level, intensifi cation of drying, thermolabile materials
Page:
909
UNIQUENESS AND STABILITY OF A SOLUTION TO AN INVERSE THERMOELASTICITY PROBLEM. 1. FORMULATION OF THE PROBLEM
The problem of identifi cation of functions of a system of one-dimensional equations of heat conduction and elastic
waves has been considered. A condition for the uniqueness of a solution has been formulated. The instability of the
solution to an inverse problem and of the problem of smoothing has been shown with the example of employment
of the iterative-variational regularization method. A fi nite-diff erence scheme has been constructed for the equation
of elastic waves in the presence of the dependence of its functions on temperature. A computational experiment has
been conducted which confi rms the instability of the inverse problem. Conclusions have been drawn on the direction
of development of the regularization method for partial diff erential equations
Author:
A. G. Vikulov
Keywords:
thermoelasticity, inverse problems, regularization, variational method, fi nite-diff erence method
Page:
918
INFLUENCE OF THE PRESSURE AND COMPOSITION OF THE FUEL MIXTURE ON ITS IGNITION BY A SUBCRITICAL STREAMER DISCHARGE
Based on the data of a physical experiment, the possibility of increasing the effi ciency of combustion of fuel in power
plants with the use of a multipoint plasma ignition of a fuel mixture in a cylindrical combustion chamber of such
an installation by a subcritical streamer discharge initiated on the combustion chamber surface by a half-wave
resonator is discussed. The dependences of the fl ame front propagation time and the rate of pressure increase in
the combustion chamber on the initial pressure and composition of the fuel mixture characterized by the fuel excess
coeffi cient, were studied. Based on the results of measurements, the optimal fuel excess coeffi cient was determined,
which provides the highest pressure and the highest rate of pressure increase in the combustion chamber during
streamer ignition of fuel in it.
Author:
P. V. Bulat , K. N. Volkov , L. P. Grachev , I. I. Esakov , P. B. Lavrov
Keywords:
combustion, ignition, microwave discharge, streamer discharge, plasma, combustion chamber
Page:
931
ANALYSIS OF THE EFFICIENCY OF COMBINED BARRIER STRIPS FOR LOCALIZING THE BURNING OF NEEDLES AND LEAFAGE
The eff ectiveness of the use of combined barrier strips consisting of moistened forest combustible material for
extinguishing a forest fi re depending on the speed of air fl ow over it has been studied. To moisten the forest
combustible material, use was made of water, an emulsion from a foam generator, a bentonite suspension, a
bischofi te solution, and an OS-5 solution. Optimal combinations of the strips of needles and foliage, moistened
with the indicated liquids, with the minimum consumption of the latter, that exclude the increase in the combustion
site area have been established
Author:
A. O. Zhdanova , A. V. Zakharevich , G. V. Kuznetsov , K. O. Ponomarev
Keywords:
forest fi re, combustion site, localization of combustion, barrier strip, suspensions, emulsions, solutions
Page:
939
FRACTURE TOUGHNESS OF NANOFIBER-REINFORCED CONCRETE ON NORMAL SEPARATION AND IN-PLANE SHEAR
Tests were carried out on various nanoconcrete matrices and with diff erent dispersed reinforcement fabric: carbon
nanotubes, basalt fi ber (polymer, 3 types of steel, and their combinations). It has been established that the value of
the stress intensity factor KIIC in the case of normal separation increases most with steel fi ber (up to 400%). Polymer
fi ber exerted the least eff ect on crack resistance up to 40%. The infl uence of dispersed reinforcement on the stress
intensity factor in the case of normal separation depends on the type of concrete matrix, on the material of fi ber
fabric, and on the quantity of the latter.
As a result of the tests, the values of KIIC have been obtained for various dispersed-reinforced nanoconcretes,
diff ering in the compressive strengths of the nanoconcrete matrix and in polyreinforcement with dispersed fabric at
diff erent structural levels. It has been established that dispersed reinforcement has a signifi cant eff ect on increasing
the crack resistance of the material. Increasing the value of KIIC relative to nonreinforced nanoconcrete was from 74
to 150% with steel wire fi ber, from 29 to 129% with steel fi ber from sheet, from 14 to 131% with polymer fi ber, and
from 22 to 124% with polyreinforced material.
Author:
E. A. Sadovskaya , E. N. Polonina , S. N. Leonovich , S. A. Zhdanok , V. V. Potapov
Keywords:
fi brous concrete, fi brous nanoconcrete, fi ber, crack resistance, fracture toughness, normal separation, critical stress intensity factor
Page:
945
EVALUATION OF SEDIMENTATION STABILITY OF A COMPLEX NANOADDITIVE
The sedimentation stability of a complex additive containing small doses of SiO2 nanoparticles and multilayer carbon
nanotubes has been confi rmed experimentally. It has been revealed that the additive remains sedimentationally
stable after mechanical mixing and retains its properties for at least 3 months after preparation. Additional mixing
with tempering water at the stage of its introduction into a concrete mixture does not contradict the traditional
options for the introduction of chemical additives.
Author:
S. N. Kovshar , E. N. Polonina , S. A. Zhdanok , S. N. Leonovich
Keywords:
sedimentation stability, SiO2 nanoparticles, multiwall hydrocarbon nanotubes, cavitation, electrical conductivity, cement samples
Page:
953
ENTROPY GENERATION ANALYSIS OF Al2O3–WATER NANOFLUID FLOW PAST A PERMEABLE CONE UNDER THE EFFECT OF SUCTION/INJECTION AND VISCOUS OHMIC DISSIPATIONS
A hydromagnetic nanofl uid fl ow past a permeable cone with heat and mass transfer has been investigated. An
incompressible, steady, laminar fl ow was used to study the entropy generation. The main aim was to fi nd the physical
parameters responsible for the enhancement of the entropy generation. The presence of nanoparticles in a base
fl uid helps to improve the heat transfer characteristics. Based on the obtained results, we can predict the entropy
variation due to the variation in the fl ow parameters. The enhancement in the slip velocity and suction/injection
parameters is shown to enhance the system effi ciency. It was found that the enhancement of diff usion leads to
maximum irreversibility and minimum effi ciency. The MATLAB built in bvp4c solver technique was used to solve
transformed ordinary diff erential equations with convective boundary conditions.
Author:
D. Dey , M. Hazarika
Keywords:
entropy generation, nanofl uid fl ow, heat and mass transfer, bvp4c.
Page:
961
COMBINED EFFECT OF OBLIQUE RIBS AND A NANOFLUID ON THE THERMAL-HYDRAULIC PERFORMANCE OF A CORRUGATED CHANNEL: NUMERICAL STUDY
The thermal-hydraulic performance of a ribbed corrugated channel in which a hybrid nanofl uid fl ows was
numerically investigated in the wide range of change in the Reynolds number of the fl uid fl ow 5000–25,000 with
the use of the k–ε model of turbulence. Rectangular oblique ribs diff erent in geometry were considered, and a
CuO/MgO–water nanofl uid was used as a working fl uid. It was established that the corrugations and the oblique
ribs in such a channel aid in increasing the heat transfer in it, and the CuO/MgO particles in the base fl uid improve
its thermophysical properties and, hence, the thermal performance of the system.
Author:
A. J. Hamad , R. K. Ajeel
Keywords:
heat transfer, oblique rib, ribbed corrugated channel, hybrid nanofl uid
Page:
970
ON PERTURBATIONS OF GEOSTROPHIC FLOW DETERMINED BY VOLUME SOURCES OF BUOYANCY AND MOMENTUM
Consideration has been given to a linear analytical model of perturbations of geostrophic fl ow of a stratifi ed rotating medium resulting from the action of stationary sources of momentum and/or buoyancy. The problem formulation appears more consistent than the ones considered in the literature. The model makes it possible to evaluate
explicitly the amplitudes of such perturbations as a function of the parameters of sources and characteristics of the
medium. One example of possible applications is the phenomena occurring during interventions of cold air into a
rather warm surface (strong temperature contrasts are, for example, frequent over the water surface in the polar
regions). In such cases, the air develops intense penetrating convection which, in rough approximation, acts on the
background fl ux as an intense volume heat source and horizontal momentum outlet (background fl ux deceleration
due to high eff ective viscosity).
Author:
L. Kh. Ingel′
Keywords:
stratifi ed rotating liquid, geostrophic fl ow, buoyancy sources, linear perturbations, analytical model, atmosphere
Page:
979
EFFECT OF THE SHAPE OF PULSES ON HEAT TRANSFER AT THE STAGNATION POINT OF A NONSTATIONARY AXISYMMETRIC IMPACT GAS–DROPLET JET
A numerical investigation was carried out to study the infl uence of the shape of pulses (rectangular, triangular,
and sinusoidal) on heat transfer at the stagnation point of an impact pulsed gas–droplet jet. It is shown that in a
nonstationary two-phase impact jet both an increase and suppression of heat transfer are possible in comparison
with stationary fl ow for all pulse shapes studied. In the region of small distances between the pipe cut and the barrier
(up to four pipe diameters) in the pulsed gas–droplet jet, the heat transfer at the stagnation point increases, while
at large distances (more than fi ve pipe diameters), the heat transfer rate decreases in the pulsed fl ow. This is typical
of all the pulse shapes studied in this work. An increase in the Reynolds number causes a decrease in heat transfer
intensifi cation, and the results of calculations for all types of signal shapes approach the stationary mode of a twophase impact jet
Author:
M. A. Pakhomov , V. I. Terekhov
Keywords:
impact nonstationary jet, droplets, shape of pulses, heat transfer, computational hydrodynamics.
Page:
985
EXPERIMENTAL INVESTIGATION INTO THE INFLUENCE OF THE INJECTION OF A GAS FROM THE SURFACE OF A SOLID SPHERE ON THE COEFFICIENT OF RESISTANCE
A novel procedure for determining the coeffi cient of resistance of a solid spherical particle during the injection of
a gas from its surface has been proposed in a wide range of Reynolds numbers. New experimental data have been
presented on the infl uence of the air injection from the surface of a solid sphere on the coeffi cient of resistance at
diff erent values of the velocity of the fl ow injected and fl owing past the particle in the range of Reynolds numbers
Re = 267–1333. A reduction of the coeffi cient of resistance of the solid spherical particle in gas injection from its
surface has been shown. An empirical dependence has been obtained of the coeffi cient of resistance of the particle
on the relation of the rate of injection of the gas and the velocity of the blowing air in a self-similar regime.
Author:
V. A. Arkhipov , S. A. Basalaev , S. N. Polenchuk , A. S. Usanina
Keywords:
solid sphere, injection of a gas from the particle surface, coeffi cient of resistance, intermediate regime, self-similar regime, experimental investigation
Page:
991
INTERACTION OF SUPERCAVITATING STRIKERS WITH UNDERWATER OBSTACLES
The interaction of supercavitating strikers with obstacles placed in water was investigated in a wide range of
intersection angles. Several options of the interaction of strikers with obstacles are considered, including through
puncturing, destruction of the striker, and ricochet. Estimation was made of the magnitude of the decrease in the
speed of strikers in the cases of through puncturing and ricochet.
Author:
A. N. Ishchenko , V. V. Burkin , A. S. D′yachkovskii , K. S. Rogaev , A. Yu. Sammel′ , A. D. Sidorov , E. Yu. Stepanov , A. V. Chupashev
Keywords:
supercavitating striker, underwater obstacle, intersection angle, through puncturing, drop in speed, destruction of the striker
Page:
997