Volume 95, №1

THERMODYNAMIC ANALYSIS OF ZONE MELTING

A thermodynamic description is given of the irreversible process of zone melting of a mixture of solids, and equations of its thermodynamic balances in matter, energy, and entropy are written. The dependence of the productivity of zone melting of the mixture on the energy used has been obtained, and it is shown that the productivity of this process is bounded from above. Estimation of the maximum productivity of zone melting of the mixture depending on the external parameters of the process has been made.  
Author:  A. M. Tsirlin, I. A. Sukin, I. N. Grigorevskii and I. O. Starodumov
Keywords:  zone melting, entropy, thermodynamics, thermodynamic balance, optimization
Page:  1

INVESTIGATION OF ELASTOPLASTIC PROPERTIES OF TUNGSTEN CARBIDE-BASED ALLOY STRIKERS IN INTERACTION WITH A STEEL TARGET BY THE COMPUTATIONAL-EXPERIMENTAL METHOD

A mathematical model has been constructed for the behavior of a tungsten carbide alloy on the basis of TC8 (tungsten carbide, 92%; cobalt, 8%) and WNFC (W–Ni–Fe–Co), or TNIC (tungsten, nickel, iron, and cobalt), in conditions of shock-wave loading. A scheme has been suggested for the process of mass loss and self-sharpening of the striker in dynamic interaction with the target. The computational-experimental method has been used to investigate the capacity of cylindrical strikers made of this composite to penetrate into a steel target at an impact velocity of 1260 m/s with account for the dependence of yield stress on the intensity of plastic deformation considering both the stage of strengthening and the stage of its structural softening in the process of deformation.  
Author:  S. A. Afanas′eva, N. N. Belov, V. V. Burkin, UDC 531.3 A. S. Diachkovskii, A. N. Ishchenko, Ya. D. Lipatnikova, K. S. Rogaev, A. Yu. Sammel′, A. B. Skosyrskii, Yu. V. Solov′eva, V. A. Starenchenko, E. Yu. Stepanov, A. V. Chupashev, A. A. Yugov, and N. T. Yugov
Keywords:  tungsten-carbide alloys, composite materials, striker (impactor), barrier, experiment, mathematical modeling
Page:  105

DEVELOPMENT OF CONDITIONS FOR ENTRY OF TWO STRIKERS INTO WATER AND ACHIEVING PARALLEL MOTION IN IT BY THEM

This article presents the results of external ballistic investigations of motion in the air of supercavitating strikers cannon-launched in a group, and a gas-dynamical picture of fl ow past two strikers in the chamber of an aerodynamic installation. Mathematical simulation of the process of fl ow past two strikers has been carried out, and their aerodynamic coeffi cients have been calculated. The conditions for cannon-launching of a group of supercavitating strikers have been determined that provide for their motion along the aerodynamic portion of the route and their subsequent entry into water with an angle between the longitudinal axes of strikers, at which their motion is stable.  
Author:  V. V. Burkin, A. S. Diachkovskii, A. N. Ishchenko, N. P. Skibina, V. V. Faraponov, and A. V. Chupashev
Keywords:  external ballistics, aerodynamics, mathematical simulation, gas dynamics, group throwing, supercavitation, striker
Page:  113

NUMERICAL INVESTIGATION OF THE WAVE FLOWS OF LIQUID FILMS INTERACTING WITH A GAS FLOW

The nonlinear partial diff erential equation, defi ning the state of the free surface of a viscous liquid layer (fi lm) interacting with a backward gas fl ow, is presented. The evolution of the periodic disturbances of this fi lm, resulting in the establishment of a regular regime of its fl ow, was numerically investigated. For a water fi lm falling vertically down under the conditions of its interaction with a reverse gas fl ow, the shapes of the waves on the gas–liquid contact surface were constructed and the wave characteristics of a regular regime of fl ow of the water fi lm (the frequency of the waves and their increment and phase velocity) and the time of establishment of this regime were calculated  
Author:  L. A. Prokudinaa and E. A. Salamatov
Keywords:  liquid fi lm, shear stress, nonlinear waves
Page:  123

INFLUENCE OF DISTRIBUTED BLOWING-IN ON A TURBULENT BOUNDARY LAYER ON A BODY OF REVOLUTION

A computational-experimental analysis of the eff ectiveness of stationary distribution of air blowing-in through a perforated surface on the properties of a turbulent boundary layer being formed on an elongated axisymmetric body of revolution under the conditions of incompressible fl ow past it at the Reynolds number ReL = 4.39·106 has been made. The blowing-in coeffi cient Cb varied over the range 0–0.01397. The Reynolds number Re** based on the momentum thickness δ** upstream of the perforated section was equal to 5603. It is shown that with increase in the longitudinal coordinate up to a distance of 600 δ** from the region of blowing-in, a steady decrease in the local friction is observed whose maximum value attains 100% directly in the region of blowing at a maximum intensity of the latter. Under the indicated conditions, the total aerodynamic drag of the body of revolution can be reduced by no less than 8.7%.  
Author:  V. I. Kornilov, E. A. Shkvar, and A. N. Popkov
Keywords:  turbulent boundary layer, body of revolution, blowing-in, perforated surface, friction
Page:  132

EFFECT OF OPENING PRESSURE AND AREA BLOCKAGE DUE TO OBSTACLES ON VENTED NATURAL GAS EXPLOSION

The computational fl uid dynamics (CFD) software FLACS is used to study the distribution of the explosion overpressure and temperature at various values of the vent opening pressure and obstacle area blockage in a typical room. The results show that obstacles cause an indoor explosion fl ame, severely deforming and destroying the shape of an external combustion fl ame. The indoor peak overpressure and peak temperature positively aff ect the opening pressure and obstacle area blockage. These two factors have the synergistic eff ect on the overpressure of the indoor gas explosion and high-temperature hazards, which exacerbates the disaster; however, in the presence of obstacles, the eff ect of the opening pressure on the explosion overpressure and temperature disasters is not clearly evident. Thus, indoor obstacles have a two-sided eff ect on the secondary external explosion and the propagation of indoor fl ame during a vented explosion.  
Author:  L. Pang, M. Jin, and K. Yang
Keywords:  gas explosion, vented explosion, obstacles, opening pressure
Page:  142

ANALYTICAL SOLUTION FOR THE PROPAGATION OF SHOCK WAVES IN A ROTATING MEDIUM: POWER SERIES SOLUTION

In this study an approximate analytical solution is obtained for the propagation of a cylindrical shock wave in a rotating perfect gas. The fl ow variable distributions in the fl ow fi eld behind the shock waves are discussed. The azimuthal fl uid velocity is assumed to vary according to the power law with the distance from the line of symmetry in an undisturbed medium, and the initial density is taken to be constant. The shock wave is assumed to be strong for small ratio (C/V)2 , where C is the sound speed in an undisturbed fl uid and V is the shock wave velocity. Approximate analytical solutions of the considered problem are obtained by expressing the fl ow variables as power series in (C/V)2 . The closed form solutions are constructed for the fi rst order. A comparison is made between the solutions obtained for rotating and nonrotating media. It is shown that the shock strength decreases due to rotation, whereas it increases with the adiabatic gas exponent.   
Author:  G. Nath
Keywords:  rotating medium, shock wave, power series method, perfect gas, similarity solution
Page:  152

INFLUENCE OF POLYMER SUPERPLASTICIZERS ON VARIOUS TYPES OF CARBON NANOMATERIALS

The article presents the results of a study of various types of carbon nanomaterials introduced into polymer superplasticizers and tests of the obtained additives in concrete. It has been established experimentally that during the growth of crystals they partially penetrate into each other and form a spatial network that pierces the entire cement stone and connects it into a single whole, due to which the compressive strength of concrete increases up to 30%. Moreover, the introduction of a plasticizer makes it possible to achieve a high water-reducing eff ect (30% and more) and leads to the appearance of a plasticizing eff ect at low and superlow water–cement ratios  
Author:  S. A. Zhdanok, E. N. Polonina, and S. N. Leonovich
Keywords:  carbon nanomaterials, plasticizer, dispersion, additive, strength
Page:  163

ON THE EFFICIENCY OF UTILIZATION OF HYDROGEN AND SYNGAS IN A SPARK-IGNITION ENGINE

The work is devoted to an experimental and design-theoretical analysis of combustion regimes of depleted compositions of gas mixtures based on hydrogen and syngas in the combustion chamber of a spark-ignition internal combustion engine. The analysis made points to the energy advantages of use of syngas compared to hydrogen. Here, on the one hand, it has been shown that the indicated effi ciency is weakly dependent on the excess-hydrogen coeffi cient, which allows the conclusion on the expediency of utilization of depleted compositions as more environmentally safe ones. On the other, the existence of a certain concentration limit has been demonstrated below which a signifi cant underburning of a fuel–air mixture, including that determined by the dynamics of the combustion front in the combustion chamber of the internal combustion engine, is observed.  
Author:  A. E. Smygalina, A. D. Kiverin, V. M. Zaichenko, and A. I. Tsyplakov
Keywords:  hydrogen, syngas, spark-ignition engine, numerical modeling, experiment, underburning
Page:  168

MECHANISMS OF MOLDING, PHASE FORMATION, AND STRUCTURING OF MATERIALS BASED IN TITANIUM BORIDES UNDER THE CONDITIONS OF COMBUSTION PROCESSES AND HIGH-TEMPERATURE SHEAR DEFORMATION

By the method of x-ray diff raction with a high time resolution, the authors have investigated the phase formation and structuring of titanium borides in the process of SHS with subsequent molding. The evolution of the structure of the material has been shown using the TiB–30 wt.% Ti composition as an example. It has been established that molding occurs due to the formation of an intermediate plastic matrix which serves two functions: the plasticizer and the reactant to form a strengthening phase. Calculations of the adiabatic combustion temperature and of the share of liquid titanium for TiB–Ti compositions with a content of free titanium of 5–80 wt.% have been carried out at temperatures of the original composition of 25–500o C. The processes of molding have been studied for TiB–Ti- and TiB2–Ti-based materials with a content of free titanium of 0–50 wt.% at temperatures of the original composition of 25–500o C  
Author:  P. M. Bazhin, A. S. Konstantinov, A. P. Chizhikov, A. D. Prokopets, M. S. Antipov, and A. M. Stolin
Keywords:  molding, SHS, combustion, high-temperature shear deformation, titanium boride, phase formation, structuring
Page:  177

NUMERICAL SIMULATION OF UNSTEADY GUNPOWDER COMBUSTION AT A RAPID RISE IN PRESSURE ON THE BASIS OF A CONJUGATE COMBUSTION MODEL

A physicomathematical model has been presented for solid propellant (gunpowder) combustion, in which account is taken of chemical reactions in the condensed and gaseous phases. Fourth-kind boundary conditions (conjugation conditions) were set on the combustion surface. The results of calculation of the N gunpowder combustion velocity at constant pressure agree well with the existing experimental data on the dependence of velocity on pressure. The results of numerical simulation of unsteady gunpowder combustion at a rapid rise in pressure have been presented. Quantitative data have been obtained on the deviation of the combustion velocity at a rapid rise in pressure from the steady values of the combustion velocity at constant pressure.  
Author:  A. Yu. Krainov and V. A. Poryazov
Keywords:  solid propellant (gunpowder), combustion velocity, rise in pressure, unsteady combustion, numerical simulation
Page:  184

ON THE TECHNOLOGY OF BIOWASTE PRECARBONIZATION IN A FLUIDIZED BED REACTOR

Within the framework of the model of ideal mixing of particles in a fl uidized bed, the conditions needed for carrying out the continuous process of precarbonization (torrefaction) of biowaste in a fl uidized bed reactor have been elucidated. The dependence of the degree of torrefaction on the average residence time of particles in the reactor and on the characteristic time of torrefaction has been established.  
Author:  Yu. S. Teplitskii, E. A. Pitsukha, and V. M. Zaichenko
Keywords:  torrefaction, fl uidized bed, biowaste, residence time, inert heat carrier
Page:  193

KINETICS OF DEHYDRATION OF VEGETABLE MATERIALS IN A DENSE BED WITH CYCLIC MICROWAVE-CONVECTIVE ENERGY SUPPLY

Certain results are presented of experimental investigation and numerical modeling of the kinetics and heat and moisture transfer in a blown dense bed of vegetable materials with convective and cyclic microwave-convective energy supply. The kinetic dependences of the dehydration of vegetable materials are analyzed and the possibility of reducing the duration of the process is shown with the example of raw-potato and celery-root particles. A comparison is made of the calculated and experimental kinetic dependences which points to their satisfactory agreement and to the adequacy of the model.  
Author:  P. V. Akulich and D. S. Slizhuk
Keywords:  heat and mass transfer in a dense bed, microwave-convective drying, drying of vegetable materials
Page:  198

NUMERICAL MODELING OF GASIFICATION OF SOLID HYDRACARBON MATERIALS IN A HEATED-INERT-GAS FLOW

A procedure of mathematical modeling of the characteristics of gasifi cation of a low-melting hydrocarbon material in the fl ow of a heated inert gas has been proposed which is based on solving the problem of coupled heat transfer in the gas in the channel and in the region occupied by the solid hydrocarbon material. Dependences of the shape of the boundaries of the solid material on the temperature of a carrier gas and on time have been obtained. Calculation results are compared with experimental results  
Author:  S. M. Aul′chenko V. I. Zvegintsev and S. M. Frolov
Keywords:  hydrocarbon materials, fl ow, channel, destruction, coupled heat transfer
Page:  20

INFLUENCE OF THE CORROSION PROCESS ON THERMOTECHNICAL CHARACTERISTICS OF HEAT PIPES OF LOW-TEMPERATURE RANGE

Results of investigation into the infl uence of a corrosion process on thermotechnical characteristics of heat pipes of low-temperature range are given. The reasons for the change in the thermotechnical characteristics of heat pipes manufactured from copper with various heat-transfer agents during their long-term functioning are considered and analyzed. The obtained data are in satisfactory agreement with the presented models of the corrosion process.  
Author:  A. I. Rudenko, A. P. Nishchik, E. A. Otrokh, and A. M. Terekh
Keywords:  heat pipe, corrosion process, long-term testing, thermotechnical characteristics, service life
Page:  206

DECOMPOSITION OF METHANE GAS HYDRATE DURING CARBON DIOXIDE INJECTION INTO A NEGATIVE-TEMPERATURE BED

The article presents a mathematical model of the injection of gaseous carbon dioxide into a porous bed that contains methane and its gas hydrate at a negative (Celsius scale) temperature, accompanied by its decomposition into a gas and ice. It is shown that, depending on the injected gas parameters, the formation of the carbon dioxide hydrate can occur in four modes. The fi rst mode is characterized by decomposition of CH₄ hydrate into ice and methane and by formation of CO₂ hydrate from carbon dioxide and ice. The second mode involves the decomposition of CH₄ hydrate into ice and methane, the melting of ice, and the formation of CO₂ hydrate from carbon dioxide and melt water. Moreover, at high values of pressure and temperature of injection, the existence of a mode is possible when methane hydrate decomposes into water and gas, and the formation of carbon dioxide hydrate occurs from CO₂ and water. The mode with the replacement of methane in the hydrate by carbon dioxide is considered as the limiting case of the fi rst mode, when the region containing methane and ice degenerates into a frontal surface of infi nitesimal thickness. Self-similar solutions have been constructed, and critical conditions separating the four modes of the course of the process have been obtained.  
Author:  M. K. Khasanov and M. V. Stolpovskii
Keywords:  gas hydrate, fi ltration, porous medium, heat and mass transfer, phase transitions, methane, carbon dioxide, ice
Page:  213

MATHEMATICAL SIMULATION OF TEMPERATURE CONDITIONS OF HYDRATE FORMATION IN THE FIELD GAS COLLECTORS OF THE WESTERN PESTSOVAYA AREA OF THE URENGOI OIL AND GAS CONDENSATE FIELD

The article presents a mathematical model of temperature distribution for a gas fl ow in a pipeline with heat transfer through the wall. The model can be used in heat-exchanging apparatuses, in fi eld and main pipeline systems of natural gas transport and of gas-collecting header. In simulation, use is made of real production data directly from the Urengoi oil and gas condensate fi eld (OGCF). The simulation is carried out in a one-dimensional (hydraulic) approximation with account for the temperature distribution across the pipe (thermal boundary layer). The model includes two independent parameters that contain information on the heat-conducting properties of the gas and pipe walls with account for the thermal insulation of the pipeline. The resulting equation is recommended to be used for calculating heat losses by the gas-collecting header. The mathematical model developed by the authors can be used in the case where there is an insuffi cient amount of information, since it allows one to obtain some parameters directly by mathematical calculation and approximation. Note that the proposed mathematical model has shown suffi cient convergence with the well-known Shukhov formula for calculating the temperature distribution for a gas fl ow in a pipeline.  
Author:  I. Yu. Bykov, A. A. Paranuk, and A. V. Bunyakin
Keywords:  hydrates, hydraulic approximation, thermal boundary layer, diagnostics of gas hydrate formation, fi eld plumes, thermal insulation, convective heat transfer
Page:  223

NEW METHODS OF CALCULATING THE PATTERNS OF OXYGEN MASS TRANSFER PROCESSES IN DYNAMIC WATER–AIR DISPERSE SYSTEMS

The paper presents the results of analysis of the main existing theories of oxygen mass transfer in dynamic water– air disperse systems. A theoretical model has been developed for the process of oxygen mass transfer, making it possible to account for the eff ect of deformation of air bubbles rising in turbulent regimes. A new calculation procedure has been proposed for the process of oxygen mass transfer developed on the basis of hydrodynamic characteristics of air bubble fl oating regimes. The use of obtained mathematical dependences will make it possible to take into account the eff ects of geometric parameters of air bubbles with a changed shape rising in turbulent regimes and, on this basis, to achieve higher accuracy of identifying technological characteristics of mass transfer processes.  
Author:  S. Yu. Andreev, M. I. Yakhkind, and K. V. Lebedinskii
Keywords:  air bubble, disperse system, oxygen mass transfer, fl oating regimes, diff usion coeffi cient, oxidizing capacity
Page:  230

TEMPERATURE OF THIN NATURAL LEATHER DURING ITS DRYING THROUGH PASTING ON A DRY SMOOTH SURFACE

An account is given of the results of solving the diff erential equation of unsteady-state heat conduction with constant thermophysical coeffi cients for calculating the temperature of natural leather in the process of its drying, when pasted on a plate. A method for simplifying the solution of a nonlinear equation by the method of piecewise-stepwise approximation of transfer coeffi cients is considered. The possibility is shown for using the solutions of the equations of unsteady-state heat conduction for low-intensity processes of drying fl at thin materials  
Author:  A. I. Ol'shanskii, S. V. Zhernosek, and A. M. Gusarov
Keywords:  moisture content, heat transfer coeffi cient, wet-bulb temperature, Biot number, thermal conductivity coeffi cient
Page:  240

INFLUENCE OF THE INLET-VALVE DIAMETER AND THE TEMPERATURE OF GASEOUS UF6 ON THE DYNAMICS OF FILLING OF TANKS WITH SMOOTH INTERIOR WALLS WITH DESUBLIMATED UF6

In the article, the authors have presented a software-implemented and verifi ed mathematical model of the process of desublimation of UF6 into vertical immersion tanks. Results of calculating the time of fi lling and the average performance of the tanks of volume 1.0, 2.0, 2.5, 3.0, and 4.0 m3 with smooth interior walls upon the change in the diameter of the inlet valve and in the temperature of gaseous UF6 in the collector have been given. It has been shown that the decrease in the gaseous-UF6 temperature from 40 to 10o C makes it possible to increase the tank′s average performance by 7.0–7.4%. The increase in the inlet-valve diameter from 5·10–3 to 65·10–3 m leads to an increase of 76.0–88.0% in the average performance of the tanks.  
Author:  A. A. Orlov, A. F. Tsimbalyuk, R. V. Malyugin, and A. A. Kotel′nikova
Keywords:  mathematical modeling, desublimation, uranium hexafl uoride, heat and mass transfer, gas dynamics
Page:  247

MATHEMATICAL MODEL AND THERMOHYDRAULIC CHARACTERISTICS OF PACKED SCRUBBERS OF CONDENSATION COOLING OF A GAS

The authors have solved scientifi c and technical problems of mathematical modeling and calculation of thermal effi ciency, and also of structural characteristics of packed scrubbers of condensation water cooling of a gas in a fi lm countercurrent regime. By simultaneous solution of the heat-balance equation and the expressions for thermal effi ciencies of a packed scrubber in the gas and liquid phases, a relation has been established between the thermal effi ciencies of condensation cooling of the gas and heating of the water. With an assigned temperature regime of cooling of the gas and its thermodynamic state, a required gas-phase thermal effi ciency is computed. To calculate the actual thermal effi ciency of a packed bed, use is made of a cellular model of the fl ow structure in the liquid and gas phases. An expression has been obtained for calculating the height of the packed bed from the assigned thermal effi ciency, structural characteristics of the packing, and fl ow rates of the gas and water. Agreement with the existing experimental data has been shown and a calculation algorithm has been given. Conclusions on the most effi cient packing structures have been drawn  
Author:  A. G. Laptev and E. A. Lapteva
Keywords:  thermal effi ciency, random and regular packings, fl ow structure, fi lm scrubbers
Page:  257

DETERMINATION OF THE THERMAL DIFFUSIVITY OF TRANSPARENT MATERIALS BY A NEW THERMOGRAPHIC EXPRESS METHOD

The thermophysical characteristics of nonmetallic materials (in particular, thermal conductivity and thermal diff usivity) account for their heat-insulating properties, the quality of processing in various laser technologies, and also signifi cantly aff ect the optical strength of power optics materials. Determination of thermophysical characteristics by traditional methods requires laborious manufacturing of specimens of certain sizes and two-sided access to them, which prevents the use of nondestructive testing of large workpieces and fi nished products. The article describes a nondestructive thermographic method of measuring the thermal diff usivity of transparent and semitransparent materials, which does not require cutting out samples from the test object and two-sided access to it. To increase the coeffi cients of absorption and emission of visible and infrared radiation of the accessible surface, thin opaque coatings or targets with a diameter of several tenths of a millimeter were used. The method was tested on eight optically transparent polymeric, amorphous, and crystalline materials diff ering in composition, spectral characteristics of light absorption, surface condition and overlapping about 2 orders of magnitude in thermal diff usivity. The described procedure demonstrated a small random error (0.5% for polymethyl methacrylate, 1.1% for polycarbonate, 2.3% for fused quartz, 3.3% for monocryslalline NaCl) at a speed of about 10 s, which makes it possible to use it for rapid diagnostics of newly created heat-shielding materials and elements of power optics.  
Author:  Yu. I. Golovin, A. I. Tyurin, D. Yu. Golovin and A. A. Samodurov
Keywords:  thermal diff usivity, thermography, point stepwise laser heating, optically transparent materials
Page:  266

DEVELOPMENT OF THE METHOD OF NONDESTRUCTIVE CONTROL OF THE DIFFUSION COEFFICIENT IN MASSIVE PRODUCTS FROM POROUS MATERIALS

Consideration is given to the modernization of a pulse method of nondestructive control of the diff usion coeffi cient with the aim of improving the accuracy of its use to investigate massive products from porous materials. The method makes it unnecessary to precalibrate the used diff usant-concentration meter and ensures a rise in the accuracy of determining the sought diff usion coeffi cient due to the possibility to select measured parameters involved in a calculation expression on portions of the static characteristic of the sensor with high sensitivity and antijamming capability. Technical implementation of the method with a data-measuring system is considered.  
Author:  V. P. Belyaev, A. G. Divin, and P. S. Belyaev
Keywords:  nondestructive control, massive product, porous material, diff usion coeffi cient, data-measuring system
Page:  277

MODELING HEAT TRANSFER IN THE CORE OF A NUCLEAR POWER REACTOR IN THE PRESENCE OF PERTURBATIONS OF HYDRODYNAMIC AND ENERGY PARAMETERS

A nonstationary two-dimensional model of numerical calculation of heat transfer in the core of a WWER-1200 reactor has been developed on the basis of representation of the core as a porous body. Nonstationary regimes occurring in the presence of local growth in the heat release in the cage and resulting in the reorganization of the fl ow fi eld in the core have been modeled  
Author:  N. V. Pavlyukevich and A. I. Shnip
Keywords:  heat transfer, reactor core, porous body, perturbation of heat release
Page:  29

COMBINED METHOD OF SEPARATION OF VARIABLES. 4. NONSTATIONARY HEAT CONDUCTION IN SOLIDS WITH BOUNDARY CONDITIONS OF THE SECOND KIND

The combined method of separation of variables applied to the solution of the initial boundary-value problems on the nonstationary heat conduction in solids canonical in shape (plate, cylinder, sphere) with boundary conditions of the second kind is presented. New schemes of calculating the eigenvalues and eigenfunctions of such a problem and the coeffi cients of expansion of its initial condition in terms of eigenfunctions are proposed and substantiated. The simplicity and, at the same time, the high effi ciency of solving this problem by the method developed in a defi nite approximation are demonstrated  
Author:  V. A. Kot
Keywords:  heat conduction equation, method of separation of variables, eigenvalues eigenfunctions, boundaryvalue problem
Page:  37

BENDING OF A VISCOUS JET EMANATING FROM A CAPILLARY

The bending of the jet of a viscous fl uid, outfl owing from a capillary, under the joint action of the inertial, viscous, and surface tension forces of the fl uid in it, was investigated. A linear model of the bending of such a jet is proposed. The dispersion relations have been obtained for the rate of increasing the disturbances of this jet. It is shown that the jet bends spontaneously. A qualitative analysis of the infl uence of the viscosity of a fl uid and the velocity of its outfl ow from a capillary on the angle of deviation of the fl uid jet formed from the capillary axis has been performed.  
Author:  A. A. Safronov, A. A. Koroteev, A. L. Grigor′ev and N. I. Filatov
Keywords:  viscous fl uid jet, jet bend, capillary hydrodynamics, stability loss, drip refrigerator-emitter
Page:  71

PSEUDOSOUND PRESSURE OSCILLATIONS CAUSED BY THE INTERACTION OF A FLUID FLOW WITH THE OBSTACLE IN THE FORM OF A CIRCULAR CYLINDER IN A PIPE

A simulation of the vibroacoustic processes proceeding in a long pipe with an obstacle in the form of a circular cylinder, in which a fl uid fl ows, has been performed with regard for the action of the vortices formed downstream of the cylinder on the dynamics of the system. On the basis of the computational procedure developed, the vibroacoustic characteristics of the system have been determined. The distributions of the gasdynamic parameters of the fl uid fl ow in the pipe and the vibroacoustic behavior of the system are discussed  
Author:  K. N. Volkov, V. N. Emel'yanov and A. G. Karpenko
Keywords:  vibroacoustics, numerical simulation, conjugate problem, pseudosound, pipe, cylinder
Page:  80

EXPERIMENTAL INVESTIGATION INTO THE EXERGY LOSS OF A GROUND HEAT PUMP AND ITS OPTIMIZATION BASED ON APPROXIMATION OF PIECEWISE LINEAR FUNCTIONS

The authors have presented experimental data on determining the thermodynamic parameters of a ground heat pump operating on Freon R407c on whose basis the exergy of the fl ow and the exergy loss in structural elements were calculated. A methodological approach to implementing the exergetic method of thermodynamic analysis has been developed on the basis of novel techniques of approximation of piecewise linear functions. An example of calculation of a ground heat pump operating on Freon R407c with account taken of the exergy of fl ows in it and their exergetic temperature, and also of the coeffi cient of performance COP of the pump has been given. The developed methodology can be used in designing novel types of low-temperature power plants: refrigerating machines, heat pumps, thermotransformers, and the organic Rankine cycle operating on new refrigerants, also on zeotropic and azeotropic mixtures  
Author:  K. V. Osintsev and S. V. Alyukov
Keywords:  heat pump, loss, mathematical model
Page:  9

MODELING THE DESTRUCTION OF AN ANISOTROPIC COMPOSITE BARRIER IN INTERACTION WITH SLENDER STRIKERS AT AN ANGLE

A numerical investigation has been made into the interaction of slender (5–20 calibers) steel cylinder strikers with orthotropic compost plates at velocities of up to 2000 m/s. The said interaction has been modeled in a threedimensional formulation within the framework of the phenomenological approach of continuum mechanics using the method of fi nite elements and the proprietary EFES software suite. We have identifi ed the eff ects of orientation of elastic and strength parameters of a composite and a striker angle of attack on the destruction of a plate and the behavior of the striker in the process of its penetration into the plate. It is shown that the existence of an attack angle of the striker in its interaction with the plate results in the loss of the striker stability and exerts a substantiated eff ect on the destruction of the barrier  
Author:  P. A. Radchenko, S. P. Batuev and A. V. Radchenko
Keywords:  impact, anisotropic material, destruction, modeling, angle of attack, interaction, striker, barrier
Page:  90

EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF PHYSICAL AND GEOMETRIC PARAMETERS OF ELONGATED STRIKERS ON PENETRATION OF BARRIERS

Experimental investigations have been conducted into the penetration of elongated strikers into massive steel barriers of low and high hardness in a broad range of variation in the initial impact conditions. It has been established that at an elongated striker′s velocity of impact against the barrier of 800–1200 m/s, its penetration into the barrier is complicated by the eff ects of barrier destruction asymmetry and loss of striker stability. The experiments have shown that in the investigated velocity range of the striker′s interaction with the barrier, the said eff ects have substantial infl uence on the striker′s penetration into the barrier  
Author:  V. M. Zakharov
Keywords:  elongated (slender) striker, barrier, impact, interaction velocity, depth of penetration
Page:  97

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