Volume 96, №5

UNIQUENESS AND STABILITY OF SOLVING THE INVERSE PROBLEM OF THERMOELASTICITY. PART 2. REGULARIZATION
Based on the analysis of direct variational methods used in the Hilbert space — the regularization method and the iterative regularization method — an iterative variational method was developed for regularization of the mathematically incorrect solution of nonlinear inverse thermoelasticity problems described by partial diff erential equations. Using the quadratic functional of the regularization method, an integral equation of the fi rst kind is obtained, which connects the norms of increments of the direct and inverse thermoelasticity problems. The solution of the inverse problem is linearized by calculating the norms in the Hilbert space of square-integrable functions. The integral equation is regularized by reducing it to the Euler equation. The discretization of the boundary-value problem, described by the Euler equation, is performed, and the resulting system of linear algebraic equations is solved. A computational experiment was carried out for the simultaneous identifi cation of two nonlinear temperature functions that confi rms the effi ciency of the method and shows that in the iterative selection of a quasi-solution for simultaneous determination of several functions, one experimental mode can be used.
Author:  A. G. Vikulov
Keywords:  thermoelasticity, inverse problems, regularization, variational method, fi nite-diff erence method
Page:  1117

NUMERICAL SOLUTION OF THE INVERSE PROBLEM OF HEATING OF A SOLID BODY BY LASER RADIATION
A study has been made of the process of heating of an inhomogeneous solid body by laser radiation, that is described by a one-dimensional parabolic equation with a volume heat source. The inverse problem of determining the law of variation in the density of laser-radiation power with the depth of the solid body has been posed. The temperature distribution through the body′s depth at a certain fi xed instant of time was used as the supplementary condition. A discrete analog of the posed problem has been constructed with fi nite-diff erence approximations. To solve the obtained diff erence problem, a special representation was proposed which allows splitting this problem into two mutually independent diff erence problems. As a result, an explicit formula has been obtained from which the law of variation in the density of laser-radiation power with the depth of the solid body is restored
Author:  Kh. M. Gamzaev
Keywords:  solid body, laser radiation, volume heat source, radiation-power density, diff erence problem, inverse problem
Page:  1128

HEAT TRANSFER DURING HEAT TREATMENT AND DRYING OF MATERIALS IN ANALYTICAL CALCULATIONS OF NONSTATIONARY HEAT CONDUCTION
The results of using numerical solutions of the equations of nonstationary heat conduction in calculating the temperature of heat-insulating materials in the processes of their heat treatment and drying are presented. An approximation of nonlinear transport coeffi cients by linear coeffi cients is considered using the method of linearization and iteration. A simplifi cation of the equation of unsteady heat conduction is proposed using the method of piecewisestep approximation of transfer coeffi cients, taking into account the continuous change in the temperature of the material over minimal time intervals
Author:  A. I. Ol′shanskii, A. N. Golubev
Keywords:  moisture content, temperature, drying, wet body, Biot number, heat emission coeffi cient
Page:  1134

INFLUENCE OF SPECIAL-PURPOSE AGENTS ADDED TO WATER ON THE LOCALIZATION AND SUPPRESSION OF THE COMBUSTION OF MATERIALS WITH IT
The heat transfer in the process of passage of droplets of fi re-extinguishing compounds through the high-temperature pyrolysis zone of combustible materials was investigated experimentally by optical diagnostics methods with the use of a program-apparatus complex for recording the sizes of droplets. The numerical and volume concentrations of droplets of fi re-extinguishing compounds based on water in a fi nely dispersed aerosol generated in three regimes were determined. The conditions of cessation of the fl ame combustion and thermal decomposition of a typical combustible material subjected to the action of water, a 5% foamer emulsion, a 10% bischofi te solution, and a 20% FR-Les-01 solution were recorded. The sizes of the droplets of the indicated fi re-extinguishing compounds and their fl ow rates necessary and suffi cient for the suppression of the fl ame combustion and thermal decomposition of typical forest combustible materials were determined.
Author:  G. V. Kuznetsov, N. P. Kopylov, A. O. Zhdanova, K. O. Ponomarev, A. S. Sviridenko
Keywords:  fi re extinguishing, evaporation, endothermal process, droplet, combustible materials, special-purpose additives, surface tension
Page:  1142

NUMERICAL SIMULATION OF THE IGNITION OF A FUEL MIXTURE BY A DISTRIBUTED SUBCRITICAL STREAMER DISCHARGE AND ITS BURNING IN A CHANNEL
A numerical simulation of the ignition of a fuel (propane–air) mixture in a combustion chamber by a subcritical streamer discharge, initiated at the wall of the working channel of this chamber in the electric fi eld with a strength lower than the breakdown one, on the basis of the gas dynamics equation defi ning the propagation of the combustion products in such a channel, the equation for the chemical kinetics of burning of a gas mixture in it, and the relation defi ning the formation and development of a streamer discharge in this mixture has been performed for diff erent values of the initial pressure in the channel, the excess of the propane in the gas mixture, and the number of streamerdischarge initiators in the channel. The results of the numerical calculations were compared with the available results of the corresponding physical experiment and experiment on the ignition of an analogous gas mixture by a multipoint spark discharge.
Author:  P. V. Bulat, K. N. Volkov, L. P. Grachev, I. I. Esakov, P. B. Lavrov, N. V. Prodan, P. S. Chernyshov
Keywords:  numerical simulation, plasma combustion, ignition, microwave discharge, streamer discharge, gas dynamics
Page:  1152

CHARACTERISTIC FEATURES OF THE HYDRODYNAMICS AND COMBUSTION OF FINE FUEL PARTICLES IN THE VORTEX ZONE OF A CYCLONE-GRATE-FIRED CHAMBER
Modeling has been performed for the motion of burning fuel particles in the vortex zone of a cyclone-grate-fi red furnace. It is shown that particles with a diameter that is larger than the hovering diameter, as a rule, have no time to burn in the swirled gas fl ow and burn down in the grate-fi red zone.
Author:  Yu. S. Teplitskii, E. A. Pitsukha, A. R. Roslik
Keywords:  combustion, vortex zone, cyclone-grate-fi red furnace, hovering diameter, fuel particle
Page:  1162

PHYSICAL MECHANISMS OF VIBRATING COMBUSTION OF SOLID BIOFUEL
The results of the study of vibrating combustion of solid biofuel are presented. It has been established that on transition to vibrating combustion, the fl ame temperature decreases, and the heat fl ux density on the combustion chamber wall increases. In this case, the combustion process is accompanied by intense acoustic radiation. A theoretical model of vibrating combustion of solid biofuel is proposed.
Author:  V. D. Geshele, I. P. Raskatov
Keywords:  vibrating combustion, solid biofuel, thermoacoustic self-excited oscillations fl ame, heat fl ux
Page:  1172

INFLUENCE OF THE RHEOLOGICAL PROPERTIES OF A POLYMER MELT ON THE HYDRODYNAMIC CHARACTERISTICS OF ITS VORTEX FLOW IN A CONVERGENT CHANNEL
The infl uence of the temperature of the fl ow of a polymer melt in a plane, convergent slot channel on the size of the vortex-fl ow region at the inlet of its slot part was considered. The fi elds of velocities, stresses, and pressure of the fl ow of a polymer melt in such a channel were constructed with the use of the modifi ed Vinogradov–Pokrovskii model generalized with regard for the nonmonotonic dependence of the viscosity gradient of this melt on its tension. The dependences of the initial viscosity of the polymer melt and the sizes of its vortex fl ow region in the channel on the temperature in it and the dependence of the sizes of the vortex zone of the polymer-melt fl ow on its rate were determined
Author:  G. O. Rudakov, G. V. Pyshnograi, D. É. Vaitsel′, Yu. A. Pavlyuk
Keywords:  rheology, viscosity, temperature, polymer melt, equation of state, two-dimensional vortex fl ow
Page:  1178

APPROXIMATION OF AN ARBITRARY FUNCTION BY A PIECEWISE CONSTANT FUNCTION AND NUMBER OF THEORETICAL SEPARATION STAGES IN A RECTIFICATION TOWER
The problem on the minimum number of constancy portions of the scalar step function approximating an arbitrary bounded function was solved. Expressions for calculating the number of theoretical separation stages in conventional and optimum rectifi cation towers have been obtained. The relationship between the number of separation stages in a rectifi cation tower and the parameters of the product fl ows, in particular, the relative volatility of the components of a mixture separated in it, was determined.
Author:  A. M. Tsirlin, A. I. Balunov, A. M. Vasil′ev
Keywords:  approximation, stages and binary rectifi cations, rectifi cation stage, rectifi cation tower, ideal operating line
Page:  1187

KINETICS OF POLYCONDENSATION IN A SPRAY OF AQUEOUS AND AQUEOUS-ALCOHOLIC SOLUTIONS OF LACTIC ACID
An advantage of spray technologies in polycondensation processes is the effi cient removal of low-molecular-weight products and heat. These advantages are based on dimensional eff ects which may lead a substantial shift of chemical equilibrium in reversible reactions. In this work, within the framework of formal chemical kinetics, the authors have modeled the dependence of the polycondensation rate on the droplet size, the composition of the reactive mixture, and the gas medium. This dependence was reproduced experimentally using the polycondensation of lactic acid as an example. Based on the results of microscopic observation of the behavior of an ensemble of sessile droplets of aqueous and aqueous-alcoholic solutions of lactic acid, the authors have constructed kinetic curves of contraction of droplets of varying size. The contraction is a result of the set of interrelated external and intradiff usion and intrakinetic processes and phase transformations whose limiting stage is the polymerization rate. The described regularities are thermodynamic in nature and must be manifested in polymerization and polycondensation with the participation of volatile monomers and solvents
Author:  V. B. Fedoseev, E. N. Fedoseeva
Keywords:  kinetics, polylactide, polycondensation, dimensional eff ect, spray, phase transitions
Page:  1196

RESULTS OF AN EXPERIMENTAL INVESTIGATION INTO THE USE OF LOW-TEMPERATURE HEAT PIPES FOR ACCUMULATION OF WINTER COLD
Refrigeration technologies are most important components in the production, transportation, and storage of milk and dairy products. The goal of this investigation is to determine the possibility of accumulating natural cold with the help of a low-temperature heat pipe and to conduct an experiment on the possibility of using this method in milk cooling systems. The use of ice formed and accumulated in milk cooling equipment using heat pipes does not require additional external energy; on the contrary, it saves it, reduces operational costs, decreases the amount of the cooling agent to be used, and provides a possibility to stop using cold producing machines. Experiments have shown that ice can form on the evaporator surface when 15% of a heat pipe′s volume is fi lled with a cooling agent. On the surfaces of copper heat pipes with an evaporator with a length of 1 m and a diameter of 22 mm fi lled with R404A or R134A refrigerants, at a temperature of the ambient air from –9 to –24^o C, there was formed an ice cylinder with a mass of 3–4 kg and a diameter of 100–120 mm. We present the results of experimental investigations and a description of a device for accumulating winter cold by ice formation with the help of low-temperature heat pipes and cooling milk with ice water
Author:  Kh. Undram and Sh. Enkh-Amgalan
Keywords:  cold accumulator, heat exchanger, ice freezing heat, milk cooler, heat pipe
Page:  1205

DIFFUSION AND DEPOSITION OF NANOPARTICLES IN AN NONISOTHERMAL CONTINUOUS-FLOW REACTOR
By way of mathematical and numerical simulation of an nonisothermic fl ow of a gas with nanoparticles in a tubular continuous-fl ow reactor with an nonuniform temperature fi eld, the infl uence of the diff usion (Brownian diff usion and thermodiff usion) of nanoparticles in this fl ow and their diff usion deposition on the walls of the reactor on the parameters of the gas-suspension fl ow in it was investigated. The problem on the two-dimensional fl ow of a nanogas suspension with a nonuniform transverse velocity profi le in such a reactor was solved. The longitudinal and transverse distributions of the concentration of nanoparticles in this suspension and its temperature in the reactor were obtained by the numerical fi nite diff erence method. The infl uence of the initial concentration of nanoparticles in the gas fl ow at the inlet cross section of the reactor and the Knudsen number of the nanoparticles (their sizes in fact) on the distributions of the characteristics of the disperse-mixture fl ow in the reactor was determined
Author:  T. R. Amanbaev
Keywords:  reactor, nanoparticles, Brownian diff usion, thermodiff usion, deposition, Knudsen number
Page:  1215

APPROXIMATE METHOD FOR CALCULATING THE VELOCITY PROFILE OF A TWO-DIMENSIONAL STATIONARY TURBULENT LIQUID FLOW
A developed stationary two-dimensional turbulent fl ow of an incompressible fl uid in channels and pipes is studied. The entire fl ow was divided into three zones: a laminar zone near the boundaries of the channel (pipe) and a transition and turbulent ones that follow. The laminar zone and part of the transition zone were combined into one zone, for which a linear fl ow velocity profi le was assumed in the channel and a parabolic velocity profi le with corresponding additional functions in the pipe. For the zone consisting of a turbulent core and the rest of the transition zone, a logarithmic fl ow velocity profi le was taken. Comparison of the results of calculations with experimental data has been carried out, which has shown their acceptable agreement.
Author:  V. N. Utesinova, V. V. Markov
Keywords:  stationary turbulent fl ow, velocity profi le, approximate method
Page:  1227

SIMULATION OF THE DYNAMICS OF WETTING THE UNDERLYING SURFACE DURING AVIATION FIRE EXTINGUISHING
A mathematical model of wetting the underlying surface on discharge of a cooling agent into a fi re site from the spillway device of the aircraft is presented. The model includes the equations of motion of polydisperse droplets in the gravity fi eld, taking into account their fragmentation, evaporation, and wind force. The results of the conducted studies show that the length of the wetted strip is determined mainly by the length of the primary cloud and, to a lesser extent, by the initial droplet velocity and the distribution of wind velocity in the atmosphere.
Author:  O. V. Matvienko, V. A. Arkhipov, O. I. Daneiko, A. S. Usanina,a S. A. Basalaev, A. M. Bulavko
Keywords:  aircraft fi re suppression, liquid–drop cloud, gravitational sedimentation, high-temperature environment, fi re site, fragmentation and evaporation of droplets, mathematical simulation
Page:  1233

MATHEMATICAL MODELING OF BINARY COLLISIONS OF INHOMOGENEOUS PARTICLES OF LIQUIDS IN A GAS MEDIUM
The authors have presented results of mathematical modeling of collisions of inhomogeneous droplets of liquids (nonmixed two-fl uid droplets and emulsions) in a gas medium between each other. A study was made of the infl uence of a set of factors on the conditions and integral characteristics of disintegration: of the temperature of the external medium, the concentration of the steam, and the Weber number. The obtained results have shown a satisfactory correlation with experimental results. It has been established that the ratio of the areas of the evaporation surface after and before the interaction as a result of the collisions of inhomogeneous droplets corresponds to the range 0.8–2. It is the central collision of droplets that is the most effi cient. Critical values of the Weber number were established above which the ratio of the areas of evaporation surfaces of the droplets after and before the interaction S1/S0 remains constant, in practice
Author:  D. V. Antonov, R. M. Fedorenko,P. A. Strizhak
Keywords:  inhomogeneous droplet of a liquid, collisions, Volume of Fluid method, emulsions, nonmixed two-fl uid droplets, mathematical modeling
Page:  1246

FILM COOLING OF A CONVEX SURFACE WITH COOLANT SUPPLY THROUGH TWO ROWS OF TRANSVERSE TRENCHES
The results of computer simulation of the effi ciency of fi lm cooling on a convex cooled surface when supplying a coolant through inclined round holes in "shallow" trenches are presented. The calculations were performed using the commercial package ANSYS CFX in the range of change of the injection parameter from 0.55 to 1.93, with the SST model of turbulence being used in the calculations. On the convex surface, a symmetry of the adiabatic effi ciency of fi lm cooling with respect to the longitudinal axis is observed demonstrating the stability of the cooling air in the near-wall layer. At small injection parameters, a transverse nonuniformity is observed with maxima of the local cooling effi ciency behind the fi lm cooling holes, whereas with an increase in the injection parameter, the transverse unevenness is reduced behind both trenches. It is shown that for the confi guration under study, the effi ciency of fi lm cooling on a convex surface is approximately the same as on a fl at surface, which is due to the acceleration of the main fl ow and the positive pressure gradient along the channel height.
Author:  A. A. Khalatov, T. V. Donik, N. A. Panchenko
Keywords:  trench, two-row scheme, convex surface, fi lm cooling effi ciency, computer simulation
Page:  1257

DEVELOPMENT OF A SUPERCAVITATING STRIKER FOR A SMALL-SIZE BALLISTIC INSTALLATION
Results have been presented of intraballistic design work aimed at identifying the main characteristics of a small caliber laboratory launcher and the composition of the propellant charge for various striker masses. Technical solutions have been obtained for sabots of supercavitating strikers accelerated in a small size laboratory ballistic installation. The level of the pressure acting on the striker, as it enters the water directly from the barrel of the installation, has been determined. Travel path ranges have been calculated for supercavitating strikers accelerated in a small size laboratory ballistic installation
Author:  A. N. Ishchenko, V. V. Burkin, A. S. D′yachkovskii, A. V. Chupashev, K. S. Rogaev
Keywords:  supercavitation, striker, motion, water, ballistic design, laboratory ballistic installation
Page:  1265

ROLE OF IONS OF VARIOUS MULTIPLICITY IN A LASER-PLASMA SOURCE FOR DEPOSITION OF NANOCOATINGS
Consideration has been given to the physical processes occurring in a laser-plasma source for deposition of nanocoatings using ion fl ows. In this source, a net is placed between a certain laser target and a copper substrate. A negative potential is applied to the net towards the target, and after it, a fl ow of charged particles predominantly made up of ions is formed. By applying a positive potential to the net towards the substrate, it is possible to control the energy of the ions moving to the substrate. In the net–substrate interval, ion fl ows of various ionization multiplicity have been found. It has been shown that with the potential of the electric fi eld in the net–substrate interval of 100 V and over, the kinetic energy of ions is suffi cient for the occurrence of secondary emission of ions from the substrate surface. The results of experiments make it possible to determine two substrate surface treatment regimes. With signifi cant electric fi elds in the net–substrate interval, it is possible to clear the substrate surface using ion etching. At low electric fi eld values, it is possible to deposit the laser target material on the substrate surface
Author:  V. K. Goncharov, G. A. Gusakov, M. V. Puzyrev
Keywords:  laser plasma, ion fl ows, nanocoatings
Page:  1271

EFFECT OF HALL CURRENTS ON THE EMHD TWO-LAYERED PLASMA HEAT TRANSFER FLOW VIA A CHANNEL OF POROUS PLATES
The temperature distribution caused by a magnetohydrodynamic two-layered liquid fl ow of ionized gases through a channel bounded by porous insulating plates with Hall currents is investigated. The heat transfer equations for a twofl uid fl ow with suction are worked out using the isothermal boundary and interface conditions. Exact solutions for the temperature distributions and heat transfer rates are obtained. The temperature fi eld dependence on signifi cant parameters, namely, magnetic, Hall, and porous parameters, ratios of viscosities, heights, and thermal conductivities, is investigated. This theoretical review can be useful for applications in diverse fi elds, such as geophysical streams, aerospace science, specifi cally modeling MHD electrical generators, Hall current accelerators, thermonuclear (fusion) power reactors, heat exchangers, aerodynamic heating, etc
Author:  T. Linga Raju, M. Naga Valli
Keywords:  magnetic and electric fi elds, immiscible fl ow, plasma, Hall eff ect, heat transfer, insulating plates, porous plates
Page:  1278

HYDRODYNAMICS OF A CYCLONE CHAMBER WITH A VARYING DIRECTION OF TANGENTIAL BLOWING
Experimental and numerical studies have been made of the hydrodynamics of isothermal fl ows in a small-scale cyclone chamber (D = 0.21 m) with two-stage diff erently directed injection of tangentially blown air (with a cocurrent and countercurrent swirl). It has been established that the character of vortex fl ow with a countercurrent swire diff ers signifi cantly from the structure of fl ow with a cocurrent swirl. The character of velocity and pressure distribution in the chamber′s volume has been revealed for the fl ows in question. Dimensionless dependences have been obtained for calculating the tangential velocity and pressure in the chamber. It has been shown that results of numerical modeling of vortex fl ows with the k–ω (SST) turbulence models for the concurrent and countercurrent air swirl are in satisfactory agreement with experimental data.
Author:  E. A. Pitsukha, Yu. S. Teplitskii, É. K. Buchilko
Keywords:  cyclone chamber, cocurrent swirl, countercurrent swirl, tangential velocity, longitudinal velocity, bottom blowing, total pressure, numerical modeling
Page:  1290

KINEMATICS AND DYNAMICS OF TRANSFORMATION OF ROTATIONAL MOTION OF PARTICLES IN A DISPERSE SYSTEM INTO MACROSCOPIC MOTION
An investigation has been made into the rotational motion of particles of a disperse system caused by hydrodynamic and magnetic forces and into its macroscopic manifestations. A method has been proposed for the rotation of such a system in a stationary fi eld for determining the main components of the dynamics and kinematics of transformation of particles′ rotation into their translational movement, i.e., the transfer of the angular momentum between individual particles and the disperse system on the whole. Factors have been established for an optimal impact on a disperse system by a magnetic fi eld and its rotation eff ects on the achievement of a goal: nondestructive control over the system′s structure or its modifi cation.
Author:  E. E. Bibik, V. D. Rodinova, E. V. Sivtsov, D. V. Grigoriev
Keywords:  rheology of disperse systems, magnetorheological eff ect, barium hexaferrite, viscosity
Page:  1304

INFLUENCE OF THE THERMOPHYSICAL PROPERTIES OF THE RESERVOIR AND FLUID ON THE TECHNOLOGICAL PARAMETERS OF THE CYCLIC STEAM STIMULATION
At present, hydrodynamic models do not allow simulation of local eff ects of thermal fi elds with suffi cient accuracy, and integral models do not take into account the steam mass fraction in the heat transfer fl uid. The purpose of this work is the analysis of the infl uence of thermophysical parameters of the reservoir and fl uid on the optimal times of stages of cyclic steam stimulation of the reservoir and of additional maximum cumulative oil recovery. For the fi rst time, an integral mode has been developed for cyclic steam stimulation, accounting for the steam mass fraction in the heat transfer fl uid and the equation of state for water. The model is based on the use of heat balance relationships for each type of cyclic steam stimulation. The steam temperature in the production interval, the initial reservoir temperature, and the heat fl ux are determined by the data from short-term dynamic temperature studies. The oil fl ow rate is determined by the Dupuis formula for a zone-heterogeneous reservoir. Optimal times for cyclic steam stimulation stages and the maximum cumulative oil recovery have been determined. It is shown that the optimal time of the heat transfer fl uid injection to the reservoir and the time of steam soak for the well increase with increase in the reservoir thickness, the heat transfer fl uid fl ow rate, and the steam mass fraction in it. Limits have been identifi ed to the applicability of cyclic steam stimulation in terms of the heat transfer fl uid fl ow rate.
Author:  A. Ya. Gil′manov, A. P. Shevelev, P. S. Lagunov, P. N. Gulyaev, A. S. Petukhov, P. A. Lyutoev
Keywords:  cyclic steam stimulation, heat balance, sensitivity analysis, steam injection rate, optimal time of the heat transfer fl uid injection, additional cumulative oil recovery, steam condensation
Page:  1311

GAS CONDENSATION COOLING AND LIQUID HEATING EFFICIENCY IN A TURBULENT BUBBLING LAYER ON A TRAY
A simplifi ed and a numerical mathematical models of gas cooling and water heating in a thin turbulent bubbling layer on a tray with cross-phase fl ow are presented. The thermal effi ciency of gas cooling is found using the ideal displacement model, and the temperature profi le in the liquid phase is found from the solution of a cell model or a two-dimensional diff erential equation of convective heat exchange with an interfacial heat source. Examples of calculating the effi ciency of water cooling of gas with diff erent humidity on sieve and valve trays are given. The results of calculations of the thermal effi ciency of gas cooling depending on the height of the gas–liquid layer, as well as on the gas velocity in the column are compared with known experimental data. Conclusions are drawn about the adequacy of the mathematical model and of the developed algorithm for calculating the heat and mass transfer characteristics of the bubbling layer. Comparative characteristics of the thermal effi ciency of sieve and valve trays are given depending on the gas velocity and diff erent heights of the liquid column. The infl uence of the variable mass of valves along the length of the tray on the increase in thermal effi ciency is shown. Conclusions are drawn on the most effi cient designs and modes of operation of bubbling trays.
Author:  A. G. Laptev, E. A. Lapteva
Keywords:  heat and mass transfer, gas cooling, bubbling, mathematical model
Page:  1320

HYDRODYNAMIC SIMULATION OF THE PROCESS OF OPERATION OF GAS-LIFT WELLS
A model of nonstationary fl ow of liquid and of a gas–liquid mixture in the reservoir–pipeline system is constructed and related equations are solved. Analytical expressions are obtained allowing one to determine the volume of the liquid fl owing through any cross sections of a pipe per unit time. Numerical calculations were made at various values of the system parameters
Author:  É. M. Abbasov, Sh. A. Kerimova, A. G. Melikov
Keywords:  diff erential equation, Laplace transform, liquid and gas motion, continuity equation, fi ltration
Page:  1329

EFFECTS OF THE HETEROGENEITY OF PRODUCING RESERVOIRS ON THE FORM OF PRESSURE DRAWDOWN CURVES IN HYDRODYNAMIC INVESTIGATIONS OF WELLS
Methods of mathematical modeling have been used to investigate the problem of pressure distribution in producing reservoirs during conducting hydrodynamic investigations of wells. Using the Laplace transform, an analytical formula has been obtained that generalizes a formula that is known in fi ltration theory and describes pressure drawdown curves for the case of producing reservoirs represented by interlayers with various fi ltration characteristics. The obtained formula includes two main terms of an asymptotic expansion at high values of time of the pressure function corresponding to the pressure drawdown curve measured in hydrodynamic investigations of wells. A method has been suggested for processing data from hydrodynamic investigations of wells in the presence of a straight-line boundary in the reservoirs, separating the permeable part of the producing reservoir and the impermeable rock. This situation may occur in a producing reservoir at a vertical rock displacement due to geological processes in the rock mass. The method is based on the use of logarithmic derivatives of the pressure function against time and allows a quantitative defi nition of the parameter relating the distance from the boundary to the reservoir piezoconductivity coeffi cient. A similar method can also be used for analyzing pressure drawndown curves in the case when the presence of an interface is due to the formation of a highly permeable part of the reservoir in the process of local fracturing in the rock. The obtained results can be used for analysis and interpretation of data from fi eld investigation of wells in heterogeneous reservoirs.
Author:  A. M. Svalov
Keywords:  producing reservoirs, hydrodynamic investigations of wells, rock heterogeneity, logarithmic derivatives
Page:  1344

IS THE THERMAL DIFFUSIVITY OF UNSATURATED SOILS A MONO-MAXIMUM FUNCTION OF THEIR MOISTURE CONTENT
The conductive heat transfer in the three-dimensional medium water–air–solid grain was investigated on the basis of the exact analytical solution of the problem on the steady harmonic 2D temperature fi eld in a composite having a doubly periodic chequered structure in the form of an isogonal tiling. An explicit expression for the diff usivity of the indicated composite depending on its volumetric moisture content has been constructed. It was established that the diff usivity of this composite reaches a physically meaningful maximum at a certain degree of its saturation with water. It is shown that the expression obtained is analogous to the solution of the classical Muscat problem on the fi ltration of oil in a doubly periodic array of production and injection wells.
Author:  A. R. Kacimov, Yu. V. Obnosov
Keywords:  porous medium, thermal diff usivity, eff ective thermal conductivity, steady heat conduction, singlemaximum function, solid fi bers, doubly periodic chequered structure, Maxwell refraction, composite four-sector square, upscaling, holomorphic functions, R-linear conjugation problem
Page:  1350

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE BEHAVIOR OF A VAPOR–LIQUID MIXTURE IN A VENTURI TUBE
A fl ashing fl ow occurs after a high-temperature liquid fl ows through a Venturi tube, forming a fl ashing region downstream of the throat and generating an adaptive back pressure which will aff ect a vapor fl ow in front of the throat. To reveal the phenomenon, the eff ect of the condensate fl ow rate on the steam fl ow rate in a Venturi tube is explored experimentally with consideration for the installation angle impact. The two-phase mixture approach is used to numerically explain the fl ashing fl ow behavior. The radial steam volume fraction is not equal in the fl ashing region, and the highest steam fraction appears near the wall. The maximum water discharge for various constructions is predicted numerically. The steam fl ow rate at the output can be maintained low if the condensate fl ow rate is near the expected value. Furthermore, fl ashing is signifi cantly more visible at smaller throat diameters, which results in a continuous increase in the radial steam volume fraction
Author:  Xinqi Han, Weifeng He, Shi-Rui Li
Keywords:  fl ashing fl ow, Venturi tube, multiphase fl ow, steam volume fraction, condensate fl ow rate
Page:  1361

IDENTIFICATION OF MATHEMATICAL MODELS OF HEAT TRANSFER OF HTSC COILS. 1. TECHNICAL TOOLS AND EXPERIMENTAL TECHNIQUE
This work is devoted to the development of a procedure for the calculation and experimental determination of the thermophysical characteristics of the stator coils of a generator operating using the phenomenon of high-temperature superconductivity. To realize the conditions close to operational ones, temperature regimes of cooling down the coil from 300 to 78 K with subsequent heating to 300 K were implemented during the experiment. The values of the thermophysical characteristics were calculated from the data of temperature measurements at the internal points of the samples. The paper presents a description of the experimental technique.
Author:  O. M. Alifanov, S. A. Budnik, A. G. Vikulov, A. V. Nenarokomov, D. M. Titov, A. V. Morzhukhina, V. V. Il'in
Keywords:  high-temperature superconductivity (HTSC) coils, inverse problems of heat transfer, iterative regularization method, cryogenic processes
Page:  1370

EXPERIMENTAL DETERMINATION OF THE THERMOPHYSICAL PROPERTIES OF A HYBRIDE STRUCTURE BASED ON GRAPHITE
To deploy a lunar habitable base, a new elemental composition of the system for providing a thermal regime is being developed. To reduce the mass and increase the reliability of the operation of a radiation heat exchanger of the system of providing thermal regime under the conditions of the lunar surface, it is proposed to replace the radiant duralumin panel of the radiation heat exchanger with heat pipes by a highly conductive radiant panel of hybrid structure based on pyrolytic graphite. This paper is devoted to determining the thermophysical properties of an anisotropic hybrid structure based on graphite. The thermal diff usivity and thermal conductivity of samples were determined by the laser fl ash method. Approximations of the dependences of the in-plane and out-of-plane thermal diff usivities and thermal conductivity of the hybrid structure from pyrolytic graphite on temperature for the temperature range 256–372 K have been obtained.
Author:  A. E. Belyavskii and N. S. Kudryavtseva
Keywords:  anisotropic hybrid structure, thermal conductivity, thermal diff usivity, laser fl ash method
Page:  1382

DETERMINING THE THERMODYNAMIC PROPERTIES OF WORKING SUBSTANCES IN A TWO-PHASE REGION
Using the refrigerant R134a as an example, the authors have given the procedure and results of calculation of a number of thermodynamic properties in a two-phase region of state
Author:  I. E. Agureev, M. Yu. Elagin, R. N. Khmelev
Keywords:  thermodynamic properties, two-phase region of state, refrigerant.
Page:  1388

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