Volume 95, №5


MODELING THE MOTION OF PARTICLES IN THE POTENTIAL FORCE FIELD WITH ALLOWANCE FOR THE RANDOM VELOCITY FLUCTUATIONS OF A MEDIUM

A study is made of the chaotic motion of particles in the potential force fi led under the infl uence of colored noise. Two fundamentally different approaches are used. In the first case, within the framework of the Eulerian approach, a closed equation is derived for the disribution density function of the random coordinate of a particle in the potential field. A conservative nonstationary equation for the probability density function in the bimodal potential is proposed. The second, i.e., the Lagrangian approach, is based on direct numerical modeling of a system of stochastic ordinary diff erential equations describing the displacement of a particle and the random velocity filed of a medium. Through the averaging of an ensemble of chaotic particle paths, the dynamics of change in the empirical probability density function in the bimodal potential is modeled. The results of modeling the dynamics of the probability density function obtained by two diff erent methods are in satisfactory agreement.
 
Author:  I. V. Derevich, A. K. Klochkov
Keywords:  probability density function, stochastic ordinary diff erential equation, conservative diff erence scheme, colored noise, bimodal potential
Page:  1089

THERMODYNAMIC ANALYSIS OF REGENERATIVE HEAT-TRANSFER PROCESSES

The process of heat transfer in a regenerative heat exchanger was investigated and the optimum values of its parameters (the durations of the heat-transfer half-cycles, the minimum surface of contact of the flows with the packing, and the duration of the total heat-transfer cycle in the heat exchanger) were obtained. The entropy production in this process was determined. The region of admissible regime parameters of a regenerative heat exchanger was constructed.  
Author:  A. M. Tsirlin, A. A. Mazikov
Keywords:  regenerative heat exchanger, half-cycles, heat transfer coeffi cient, entropy production, optimization
Page:  1101

DISTRIBUTION OF TEMPERATURE AND ELECTRIC FIELD INTENSITY IN A CYLINDRICAL LAYER OF POLYMER DIELECTRIC

A nonlinear one-dimensional problem has been formulated for steady heat conduction at a constant difference of electric potentials on the inner and outer surfaces of a cylindrical layer of polymer dielectric with a temperature dependent thermal conductivity coefficient and specific electrical resistivity. A fixed temperature value on the inner surface of this layer is assumed, and a total thermal resistance between its outer surface and the surrounding environment is assigned. The problem formulation is transformed to integral relations making it possible to calculate distributions of temperature and electric field intensity through the layer thickness. An example is provided of a quantitative analysis of these distributions for a cross-linked polyethylene layer. The results of such analysis make it possible to identify possible areas of application of polymer dielectrics in various electric devices, including those used as electrical insulation of high-voltage direct-current cables and to establish conditions of a thermal breakdown of a dielectric layer  
Author:  V. S. Zarubin, G. N. Kuvyrkin, I. Yu. Savel′eva
Keywords:  nonlinear heat conduction problem, polymer dielectric, electrical insulation of high-voltage cables, integral relations
Page:  1108

CONVECTIVE HEAT TRANSFER IN THE PRE-NOZZLE VOLUME OF A SOLID ROCKET MOTOR WITH A RECESSED NOZZLE

Consideration is given to the matters of mathematical simulation of heat transfer processes in the pre-nozzle volume of a solid rocket motor with a charge with a star-shaped cross section and a recessed vectorable nozzle. Mathematical simulation methods are used to solve a quasistationary spatial conjugate heat transfer problem. A comparison of the numerical simulation results with the existing experimental data has shown the correctness of the proposed models, schemes, and algorithms. Investigations have been made into the topological features of the structure of a viscous compressible heat-conducting gas near the input surface of a recessed nozzle and into their effects of convective heat transfer in the pre-nozzle volume of a solid rocket motor. For the considered configuration of a solid rocket motor, criterion equations have been proposed for estimating the dimensionless heat transfer coeffi cient in the recessed nozzle region. The conducted verifi cation of the obtained dependences using the existing experimental data confirms the correctness of the proposed criterion equations. It has been established and shown that the use of the well-known extended empirical Eckert and Kraussold dependences does not allow a correct estimate of the value of heat fluxes in the vicinity of the impermeable surfaces of the engine combustion chamber. Based on the calculation results, criterion equations have been proposed for calculating the Nusselt number in special points on the input surface of the end face of the charge.  
Author:  B. Ya. Benderskii, A. A. Chernova
Keywords:  solid rocket motor, pre-nozzle volume, recessed nozzle, star-shaped charge, mathematical simulation, criterion equations, Nusselt number
Page:  1118

HEAT TRANSFER IN A CYLINDRICAL CRUCIBLE WITH LIQUID METAL IN ITS ALTERNATE EXPOSURE TO TRAVELING AND ROTATING MAGNETIC FIELDS

A description is given of experimental investigations of the process of heat transfer in a cylindrical container with liquid gallium in its alternate exposure to traveling and rotating magnetic fields. In the experiment, we created the process of two-directional electromagnetic MHD-stirring of liquid metal similar to the process of stirring in the hot top of the crystallizer of a continuous casting machine for round ingots from aluminum and its alloys. To control the front of directed crystallization of the ingot, the flow must be symmetrical with respect to the longitudinal axis. In the experiment, we implemented an alternate exposure to traveling and rotating magnetic fields ensuring such symmetry of the flow being generated. Heat was transferred from the heater on the alloy surface to the thermostated bottom of the container. In the experiments, thermal measurements were used to investigate heat transfer in the container in the direction of its vertical axis, and also estimates were made of the time of stirring the introduced impurity at various regimes of MHD-stirring of liquid metal. It has been found that the heat transfer eff ect is best ensured by poloidal flow, but the creation of additional azimuth flow signifi cantly decreases this eff ect. It has been found that in alternate exposure of liquid metal to traveling and rotating magnetic fields, the heat transfer effect occurs in a way similar to traveling and rotating magnetic fields acting on the metal simultaneously and continuously.  
Author:  S. Yu. Khripchenko
Keywords:  semicontinuous cylindrical ingots, two-directional MHD-stirring, experiment, heat transfer, stirring time, alternate regime
Page:  1126

MATHEMATICAL SIMULATION OF HEAT TRANSFER THROUGH THE MULTILAYER FILLER STRUCTURES OF BUILDINGS

The nonstationary heat transfer through the multilayer filler structures of a building in which the temperature of the air is unknown was investigated using the heat conduction equation with the asymmetric third-kind boundary conditions. For determining the change in the temperature inside a building, necessary for selecting the materials of its filler structures, the Cauchy problem was considered and solved by numerical methods. On the basis of computer simulation of the heat transfer through diff erent multilayer filler structures of buildings, the regimes of heat transfer through such a structure were investigated for the cases where the temperature of the outdoor air changes by the linear and sinusoidal laws.  
Author:  F. G. Akhmadiev, R. F. Gizzyatov
Keywords:  mathematical simulation, nonstationary heat transfer, fi ller structures, numerical methods, computer simulation
Page:  1134

BOILING ON A SUBSTRATE. CRITICAL SIZE OF THE BUBBLE

The free energy of formation of a vapor bubble in a conical cavity of a substrate is calculated. An approximate formula is obtained for the characteristic length of the critical bubble. It has been established that the length of such a bubble depends on the angle of wetting and is inversely proportional to the overheating of the liquid. For freon R495, the calculated dependences of the free energy of the critical bubble on the cone apex angle and the wetting angle are given. It is shown that in the case of the same heating in a fairly wide range of these angles, the free energy of bubble formation is much less than in a homogeneous liquid.  
Author:  S. P. Fisenko
Keywords:  contact angle, free energy, freon, conical cavity, overheating
Page:  1145

THEORETICAL FOUNDATIONS OF INTERNAL ENERGY SAVING DURING RECTIFICATION

Consideration has been given to internal energy saving during rectification, which takes account of the multiple condensation of the steam on column plates. The mechanism of heat and mass transfer between the liquid and the steam has been analyzed. An expression has been given for quantitative assessment of the internal energy saving during rectification. It has been substantiated theoretically that for the scheme of separation of ternary mixtures with the release of a high-boiling component in the first column, there is a region of original compositions, for which heat expenditures turn out to be the lowest. An expression has been given that describes the boundary of optimality domains of different separation schemes. Calculation of the expenditures of heat, performed with the Aspen Plus package for the two schemes of rectification of ternary mixtures has confirmed the theoretical substantiation of the presence of optimality domains for each. Using the notion of internal energy saving, the advantage of one or another scheme of separation of a ternary mixture has been explained.  
Author:  M. K. Zakharov
Keywords:  rectifi cation, binary mixtures, ternary mixtures, refl ux ratio, minimum steam fl ow, internal energy saving during rectifi cation
Page:  1149

CRITERIA FOR THE STABILITY OF DISPLACEMENT PROCESSES DURING THE PRODUCTION OF HYDROCARBONS

Consideration has been given to the stability of the process of displacement of oil by water in piston-like and multiphase approximation with account for gravitational forces. By analogy with a gravitation-free regime, a critical parameter determining a stable displacement process has been introduced. This parameter is characterized by the relation of mobilities of fluids separated by a displacement front. However, it has been shown that in case of accounting for gravitational forces, this parameter cannot provide a sufficient condition for the formation of an unstable process, since gravitational forces can have a stabilizing or destabilizing effect on the stability of displacement. Therefore, a second critical number accounting for the above-mentioned effect has been introduced. To identify the critical numbers for a two-phase model, it is necessary to solve a Buckley–Leverett problem, for which purpose use was made of the Weldge graphical technique in this investigation, which made it possible to calculate water saturation on the displacement front after whose determination the calculation and analysis of the critical numbers were conducted. The calculation was conducted on model values of input parameters. It has been shown that the stabilization of the displacement front with gravitational forces is possible at rather low flow velocities.  
Author:  Ya. A. Kryazhev, V. A. Kryazhev, A. P. Shevelyov, A. Ya. Gil′manov
Keywords:  piston-like displacement model, two-phase displacement model, Buckley–Leverett′s problem, displacement front stability, exposure to gravitational forces, rheology, mechanics of multiphase systems
Page:  1156

SIMULATION OF HEAT TRANSFER IN THE PROCESS OF OIL DISPLACEMENT BY THE HOT WATER IN A CONJUGATE STRATUM–WELL SYSTEM

A model of the pumping of a hot liquid into an oil-bearing stratum with a well has been constructed, and the boundary-value problem on the nonstationary heat transfer in the conjugate stratum–well system was solved. The heat losses in the bore of the well and the temperature field of the water pumped into the stratum were determined. It is shown that heat propagates within a small region in the stratum. Numerical calculations were performed using the analytical expressions obtained for practically important values of the parameters of the stratum–well system  
Author:  É. M. Abbasov, G. R. Agaeva, T. S. Kengerli, A. O. Darishova
Keywords:  temperature, heat transfer, liquid, fi ltration, Laplace transform, convective heat transfer
Page:  1164

INFLUENCE OF CONVECTIVE PROCESSES ON TECHNOLOGICAL PARAMETERS OF CYCLIC STEAM STIMULATION OF OIL RESERVOIRS

The focus of the article is simulating the technology of cyclic steam stimulation of producers for heavy-oil fields and analyzing the influence of convective processes on basic technological parameters. With the model taking account of gravitational segregation and convective heat fluxes of the steam, technological indices of the process have been determined, including the time of steam injection and the time of steam-thermal condensation. The process of cyclic steam stimulation is described by the integral model which is based on heat balance. The rotation of the coordinate system makes it possible to consider quasi-one-dimensional solutions. A comparison of model and field data on the Sho-Vel-Tum field was made, which has shown a satisfactory agreement. In the course of numerical experiment, it has been shown that the expectation time for the full condensation of the steam, which leads to the well shutdown, is unjustifi ably overstated at this field. It has been shown that account taken of convective flows of the steam enables one to raise the accuracy of prediction of steam-injection intervals. Long-term preservation of the effect of cyclic steam stimulation has been established for cumulative additional oil recovery as applied to the Sho-Vel-Tum field.  
Author:  Ya. A. Gil'manov, A. R. Arazov, A. P. Shevelyov
Keywords:  engineering problems of high-viscosity-oil recovery, producer, cyclic steam stimulation, heat balance, cumulative oil recovery, steam injection time, steam-thermal condensation
Page:  1172

SORPTION–DESORPTION OF WATER VAPOR BY LINEAR AMORPHOUS POLYMERS

The laws governing sorption–desorption of water vapor by microporous sorbents based on linear amorphous polymers (polystyrene, polyvinyl chloride, and polymethyl methacrylate) have been studied. A mathematical model of sorption–desorption hysteresis is presented. Based on the proposed model, it is shown that the sorption– desorption process is aff ected by the presence of free active centers of the polymer, which interact with water molecules.  
Author:  V. M. Gud′, V. V. Zhukovskii, N. A. Zhukovskaya
Keywords:  water vapor, sorption, desorption, microporous sorbents, linear amorphous polymer, polystyrene, polyvinyl chloride, polymethyl methacrylate
Page:  1180

DEVELOPMENT OF SELECTION METHODS FOR THE PRIMARY AND SECONDARY CAPILLARY STRUCTURES OF LOOP HEAT PIPES

Possible configurations of loop heat pipe evaporators have been analyzed, and the current state of experimental and theoretical studies on the choice of their capillary structures with a real pore size distribution function has been presented. On this basis, a methodology for selecting capillary structures for the primary and secondary loop heat pipe wicks with various operational parameters has been proposed. The operating conditions of loop heat pipes and the method of analytical calculation of the temperature fi eld for a model with pseudoconvection in capillary structures have been formulated. The calculated and experimental data have been compared.  
Author:  V. Kiseev, O. Sazhin
Keywords:  loop heat pipe, evaporator, capillary structure, capillary pump
Page:  1187

PLASMA-CHEMICAL SYNTHESIS OF NANODIAMONDS ON THE SURFACE OF A MICROARC DISCHARGE CATHODE

The results of plasma-chemical synthesis of nanodiamonds from carbon nanostructures in a microarc discharge are presented. The electrodes used in the experiments were a molybdenum cathode and a copper anode coated with carbon nanostructures, such as carbon nanotubes, fullerene soot, and graphene. The formation of carbon nanostructures on the surface of the copper electrode was carried out in an electric arc embedded in a liquid hydrocarbon. At the next stage, these carbon nanostructures served as a source of atomic carbon from the surface of the anode of the microarc discharge. It was found that carbon nanotubes, graphene, and nanodiamonds are synthesized on the cathode surface. A signifi cant infl uence on their formation is exerted by both the surrounding gaseous medium, and the electrophysical parameters of the arc discharge (current and electric fi eld intensity distribution). Two types of nanodiamonds of size 50–100 nm and 5–10 nm have been synthesized, with large nanodiamonds being located separately and small ones as a necklace. The time of formation of microdiamonds is several tens of seconds, which diff ers by orders of magnitude from those obtained by traditional methods of their production.  
Author:  B. A. Timerkaev, R. K. Gevorgyan, A. A. Zalyalieva, D. B. Timerkaeva
Keywords:  nanodiamonds, artifi cial diamonds, plasma chemistry, electric arc, heavy hydrocarbon material, black oil, submerged arc discharge
Page:  1201

TOWARDS THE UNDERSTANDING OF THE MELTING HEAT TRANSFER IN A Cu–WATER NANOFLUID FLOW

The infl uence of the melting heat on the hydromagnetic convective Cu–H2O nanofl uid fl ow over a stretching plate was investigated. The eff ects of viscous dissipation and Joule heating, involved in the energy equation, were considered. The primary equations were reduced to the ordinary diff erential equations with the use of suitable similarity transforms. The reduced equations were solved using the shooting technique by the fourth-order Runge– Kutta scheme. A detailed investigation is exemplifi ed by diagrams and tables for various values of opposite factors. The results of calculations were compared with the corresponding literature data obtained for specifi c situations.  
Author:  K. Das
Keywords:  computational mathematics, nanofl uid, melting heat transfer, magnetic field.
Page:  1207

HEAT TRANSPORT PERFORMANCE OF NANOPARTICLES IN GASES: CASE STUDY OF Al2O3 NANOAEROSOL

The concept of nanofluids has already shown that the heat transfer potential of traditional working fluids could be improved by dispersing various nanosized particles in them. Up to now, liquids are used as the base materials and dispersed nanoparticles are solid. In the present paper, we study solid nanoparticles dispersed in a gaseous medium (nanoaerosol), and the behavior of heat transfer of nanoparticles mixed with a gas fl ow is analyzed. Nanoparticles of Al2O3 mixed with an air stream are considered inside a tube subjected to a constant heat flux of 696.534 kW/m2 . The timescale analysis of heat transfer in a nanoparticle–gas mixture is carried out. The effect of the particle volume fraction and the Reynolds number Re on the convective aerosol heat transfer coeffi cient and the Nusselt number is analyzed. The timescale study shows that conduction is dominant in a nanoaerosol. The maximum 59% and 55.27% enhancements in the convective aerosol heat transfer coefficient and the Nusselt number, respectively, are obtained with increasing the particle volume fraction in the range 0.002–0.01 and Re in the range 8000–20,000. These characteristics are compared with the values based on different correlations, and the results are shown to fall in the acceptable region. Moreover, particle inclusion and the rise in Re yield the maximum enhancement in the flow exit temperature equal to 1.72%. Finally, nanoaerosol-based coolants are recommended as the future of gas-based cooling systems.  
Author:  V. Khadanga, S. Mukherjee, P. C. Mishra, S. Chakrabarty
Keywords:  nanoaerosol, nanoparticles, heat transfer, convective aerosol heat transfer coeffi cient, heat transfer performance
Page:  1214

DETERMINATION OF LIMIT VELOCITIES OF SUPERCAVITATING MOTION OF STRIKERS FROM VARIOUS MATERIALS IN WATER

Experimental-theoretical investigations have been conducted into underwater supercavitating motion of cone strikers from various materials in a broad range of velocities. An estimate of the range of strikers′ velocities has been performed for the implementation of their nondestructive entry into water and motion in it in a supercavitating regime. A possibility of an accurate hit by supercavitating strikers on underwater barriers in a supersonic range of motion velocities has been shown.  
Author:  A. N. Ishchenko, V. V. Burkin, A. S. D′yachkovskii, A. Yu. Sammel′, A. V. Chupashev
Keywords:  cavity, supercavitation, high-velocity motion, striker, supersonic motion regime, experimental setup, underwater barrier
Page:  1222

SIMULATION OF THE AERODYNAMICS OF A SWIRLING TURBULENT FLOW AND OF THE PROCESS OF CLASSIFICATION OF PARTICLES IN A VORTEX CHAMBER

A numerical study of the aerodynamics of a swirling turbulent fl ow and of the classifi cation of particles in the vortex chamber of a pneumatic combined apparatus has been performed. The obtained results indicate the possibility of achieving a uniform distribution of the radial fl ow velocity along the height of the chamber in the particle separation zone in it by changing the shape of the rotor blades of the apparatus, which is a prerequisite for its effi cient operation. The trajectories of motion of single particles in the vortex chamber are determined. A signifi cant eff ect of turbulent fl ow pulsations on the effi ciency of particle separation in it has been established. The reliability of the obtained results is confi rmed by test studies and by their comparison with experimental data.  
Author:  R. R. Turubaev, A. V. Shvab
Keywords:  numerical simulation, turbulence, pressure, aerodynamics, vortex, swirling fl ow, stream function, Wilcox model.
Page:  1230

CALCULATION OF THE ACOUSTIC CHARACTERISTICS OF THE FLOW OF A COMPRESSIBLE VISCOUS GAS OVER A CIRCULAR CYLINDER

The generation of noise by the fl ow of a compressible viscous gas over a circular cylinder as a result of the formation of vortices in it and the separation of them from the surface of the cylinder was considered. The sound fi eld of this fl ow was calculated using the method of simulation of large vortices, and its acoustic characteristics were determined using the method of acoustic analogy based on the solution of the Ffowcs Williams–Hawkings equation. On the basis of the direct numerical simulation data on the indicated fl ow, its regimes at diff erent Reynolds numbers were investigated. The results of calculation of the acoustic characteristics of this fl ow within the framework of the two- and three-dimensional approaches to the solution of the Ffowcs Williams–Hawkings equation were compared. A good agreement has been obtained between the calculated gasdynamic and acoustic characteristics of a gas fl ow over a circular cylinder and the corresponding experimental and calculation data available in the literature.  
Author:  K. N. Volkov, V. N. Emel′yanov, A. G. Karpenko, P. S. Chernyshov
Keywords:  aeroacoustics, computational gas dynamics, cylinder, noise, fl ow separation, vortex, directional diagram
Page:  1239

INFLUENCE OF INJECTION OF THE THERMAL SHIELD DECOMPOSITION PRODUCTS ON THE FLOW COEFFICIENT OF A RECESSED NOZZLE DEPENDING ON THE INLET SECTION SHAPE

The infl uence of injection of the products of ablation of a heat-shielding coating of a recessed nozzle with the inlet section of radial and ellipsoidal shape on the fl ow coeffi cient of a solid propellant rocket engine has been estimated. The studies were carried out by the modern methods of computational fl uid dynamics in a quasistationary formulation. The boundaries of the change in the fl ow coeffi cient depending on the intensity of injection of decomposition products into the main fl ow are determined in accordance with the change in the heat fl ux to the surface of the heat-shielding coating. The infl uence of the shape of the inlet section, its geometric parameters, and of the temperature of decomposition products on the fl ow coeffi cient is shown.  
Author:  A. N. Kirillova, A. N. Sabirzyanov
Keywords:  solid-propellant rocket engine, recessed nozzle, heat fl ux, injection of ablation products, fl ow coeffi cient, computational fl uid dynamics
Page:  1248

NUMERICAL ANALYSIS OF GAS-DYNAMICAL AND MECHANICAL OXIDATION PROTECTION AGAINST OF THE HEAT-AFFECTED ZONE DURING COAXIAL LASER CLADDING

Results of investigations into the dynamics of inert-gas jets formed by a triple coaxial nozzle in the region of interaction of laser radiation with the treated material in laser cladding have been presented. An analysis has been made of the mechanisms of admixing of the oxygen from the surrounding air medium to the jet of protective inert gas above the heat-aff ected zone (HAZ) on a part′s surface. It has been shown by calculation that the mass fraction of the oxygen above the HAZ is very high, which may result in the oxidation of the metal surface. Schemes of use of a protective screen, insulating mechanically the inert-gas jets and the region of their interaction with the treated part from the environment have been proposed. Results of numerical investigations into the character of gasdynamic fl ows for the proposed schemes of mechanical protection have been presented. When the protective screen is installed, the oxygen concentration near the treated surface of the product decreases by several orders of magnitude, which prevents the oxidation of the metal in the HAZ because of the action of laser radiation in wide limits of variation in the regime parameters of cladding. Distinctive features and the quality of oxidation protection of mechanical surfaces in laser processing of plane and cylindrical long-dimensional products have been discussed.  
Author:  D. V. Bedenko, O. B. Kovalev
Keywords:  numerical modeling, gas dynamics, mixture of gases, oxidation protection, turbulence, laser cladding, coaxial nozzle
Page:  1259

TECHNIQUE OF TRANSFERRING FLUID MASS AND VOLUME UNITS IN A FLOW AND OF MASS AND VOLUMETRIC FLOW RATES OF FLUID BY MEANS OF INDIRECT MEASUREMENTS

Theoretical foundations of the technique of transferring fl uid mass and volume units in a fl ow, as well as of mass and volumetric fl ow rates of fl uid by means of indirect measurements are considered. The equation of the mass rate of fl ow (of mass) of the fl uid has been modifi ed with regard to fl uctuations in the fl uid fl ow rate and transient processes in operation of a fl ow switch with the use of the continuity equation and of the methods of mathematical statistics. The main sources of uncertainty of verifying installations with weighing devices are revealed. The results obtained on approbation of the technique of transferring fl uid mass and volume units in a fl ow, as well as of mass and volumetric fl ow rates of fl uid by means of indirect measurements on verifying installations with weighing devices in a wide range of geometric and operating parameters are presented. The expanded uncertainty of measurements by verifying installations with weighing devices in the case of transferring fl uid mass and volume units in a fl ow, as well as of mass and volumetric fl uid fl ow rates by the method of indirect measurements is compared with the uncertainty of measurements by the comparison method with the use of the comparison standard.  
Author:  A. V. Shchelchkov, R. A. Korneev, V. A. Fafurinc
Keywords:  continuity equation, velocity profi le, nozzle cut, fl uid fl ow rate, turbulent pulsations, uncertainty budget, indirect measurement method, comparison standard
Page:  1271

VIBRATORY COMBUSTION, PROBLEMS AND INVESTIGATION METHODS

Literature data have been reviewed and their analysis has been made. With account taken of the analysis of the modern status of research, a procedure of experimental investigation of the combustion of solid fuels has been developed. The diagnostic system made it possible to measure the rate of burnup of the fuel and the amplitude and frequency of pulsations of the gas pressure in a Rijke tube. A theoretical model of vortex vibrations of the fl ame during vibratory combustion has been developed.  
Author:  O. G. Stonik, V. D. Geshele, S. A. Kovalev, I. P. Raskatov, A. A. Kozlova
Keywords:  vibratory combustion, self-oscillation, acoustic radiation, combustion intensity, frequency, solid fuel
Page:  1282

NUMERICAL MODELING OF HIGH-ENTHALPY TWO-PHASE FLOW IN A CHANNEL WITH TRANSVERSE INJECTION OF A REACTIVE LIQUID

The authors have performed numerical modeling and have analyzed, from the results of calculation, distinctive features of two-phase flow in a channel of constant cross section upon traverse injection of a reactive liquid through spray injectors. A model hydrocarbon fuel with thermophysical properties similar to TS-1 kerosene has been considered as the reactive liquid. The characteristics of spraying and evaporation of liquid droplets in a highenthalpy subsonic air flow have been obtained by mathematical modeling, and an analysis has been made of the quality of mixing and the intensity of combustion of a two-phase mixture. Also, the regularities of the influence of the number of injectors and the pressure diff erence in them and of the mass flow rate of the reactive liquid on the intensity of processes occurring in the channel have been obtained.  
Author:  K. Yu. Aref′ev, A. V. Voronetskii, A. N. Prokhorov, S. A. Suchkov, L. A. Filimonov, M. A. Abramov
Keywords:  mathematical modeling, injection of a liquid, evaporation of droplets, channel of constant cross section
Page:  1290

MODELING OF THE THERMOCHEMICAL CONVERSION OF PLANT BIOMASS

Based on experimental studies of the thermochemical conversion of plant biomass in the form of wood waste, flax awn, straw, sunfl ower husks, and fallen leaves, a model was developed for calculating the yield and composition of decomposition products. A pilot plant for thermochemical conversion is described, and experimental data on the yield and composition of the products of thermal decomposition of plant biomass are obtained, a comparison of which with the results of calculations showed their good agreement.  
Author:  G. I. Zhuravskii, V. V. Savchin
Keywords:  thermochemical conversion, plant biomass, decomposition products, modeling, pilot plant
Page:  1298

CHLORINE DISTRIBUTION IN PYROLYSIS OF CHLORINE-CONTAINING MEDICAL WASTE

Results are presented of an investigation into the pyrolysis of components of a model mixture of medical waste of standard composition and of the entire mixture in a fixed-bed reactor using the methods of thermogravimetric analysis. Data on the regular patterns of chlorine redistribution between the pyrolysis products are presented. It is shown that in pyrolysis of a medical waste mixture whose composition includes chlorine-containing components, chlorine is partially released into the gaseous phase in the form of HCl and partially retained by semicoke. In this case, the degree of chlorine retention by semicoke depends on the ash content of the starting material and the composition of its mineral part  
Author:  G. I. Dvoskin, V. F. Kornil′eva, V. V. Khaskhachikh, G. Ya. Gerasimov
Keywords:  medical waste, pyrolysis, fi xed-bed reactor, thermogravimetric analysis, chlorine-containing components
Page:  1305

EXPERIMENTAL AND THEORETICAL STUDY OF THE GASIFICATION OF A LOW-CALORIE SOLID FUEL IN THE REGIME OF SUPERADIABATIC FILTRATION COMBUSTION

The authors have presented results of experimental and theoretical studies on combustion and gasifi cation of mixtures of various kinds of solid fuel (wood pellets, wood chips) with the inert (spheres of alumina, crushed chamotte brick) in a vertical reactor operating on the principle of superadiabatic filtration combustion. Experimental data (temperature and the wave velocity) have been obtained for different concentrations of the fuel in the inert, kinds of fuel, and flow rates of the air. To determine the localization of a reaction zone and the thermal-wave velocity, use was made of the data of infrared-imaging measurements. A physicochemical model of filtration combustion of a solid fuel with an inert filler in a superradiative-wave regime has been created. Calculations of the thermodynamic characteristics of combustion and the equilibrium composition of combustion products have been done for a wide range of mixtures of wood and air. Calculated dependences of the temperature distributions and the velocity of the combustion front and the thermal wave have been obtained for different concentrations of the wood in the inert and flow rates of the air  
Author:  N. M. Gorbachev, S. I. Futko, A. V. Vlasov, M. I. Rusakevich, I. A. Koznacheev, N. I. Stetyukevich
Keywords:  biomass, wood, gasifi cation, pyrolysis, municipal solid waste, fi ltration combustion, superadiabatic eff ect, superadiabatic combustion wave, thermal wave, mathematical modeling
Page:  1312

METHODOLOGICAL RECOMMENDATIONS ON OBTAINING A TARGET FUNCTION AND SOLVING PROBLEMS OF OPTIMIZING METHODS AND DEVICES FOR MEASURING THERMOPHYSICAL PROPERTIES OF SUBSTANCES

In selecting optimal values of regime parameters of the methods and basic design dimensions of a device for measuring thermophysical properties of substances, it is necessary to correctly assign a target function (functional) used for formulating and solving problems of optimization. The results of this work determine a successful performance of work on solving problems of optimizing designed methods and devices for measuring thermophysical properties of substances and materials.  
Author:  S. V. Ponomarev, V. O. Bulanova
Keywords:  thermophysical properties of substances, target function, optimization problem, methods of mathematical metrology, theory of errors, mathematical physics
Page:  1322

OBTAINING HIGH-QUALITY OPTICAL SURFACES OF ELEMENTS BASED ON POLYCRYSTALLINE ZINC SELENIDE (CVD-ZnSe) THAT IS DOPED BY TRANSITION METALS IN THE PROCESS OF MECHANICAL, CHEMICAL MECHANICAL, AND MAGNETORHEOLOGICAL TREATMENT

The authors have developed procedures of mechanical, chemical mechanical, and magnetorheological polishing that allow obtaining surfaces of optical elements of high optical quality on the basis of high-purity polycrystalline zinc selenide doped by ions of transition metals (Cr2+:ZnSe).  
Author:  E. M. Gavrishchuk, S. A. Rodin, O. V. Timofeev, A. L. Khudolei,c G. R. Gorodkin, V. L. Kolpashchikovc
Keywords:  polycrystalline zinc selenide, high-quality treatment of surfaces of optical elements
Page:  1335

SMALL-SIZE PLANAR WWAN/LTE RANGE LOOP ANTENNA MANUFACTURED USING A NEW COMPOSITE MATERIAL FOR 5G-TECHNOLOGY APPLICATIONS

Consideration has been given to the possibility of ensuring a high level of broadband signal power in the tracts of a wireless device between the sending–receiving module and the antenna fabricated using various materials up to sounding in the most frequently used ranges, viz., 3G, 4G, and 5G. It is suggested that the required level of power transfer be achieved using composite materials with controlled microwave properties (dielectric and magnetic permeabilities) whose variations change the wave resistance and geometric dimensions of the microstrip line, which expands the opportunities for ensuring the required electromagnetic characteristics of a mobile device. In the course of investigation, an estimate was made of the possibility of using a mobile antenna fabricated using a composite material on the basis of fl uorinated ethylene–propylene in combination with strontium hexaferrite SrFe12O19 for advanced fi fth-generation systems without excluding the possibility of the antenna′s operation in systems of the second, third, and fourth generations. Advantages of using composite materials in implementing antenna devices in 5G technologies are shown.  
Author:  A. A. Sut′ko, T. I. Zubar′, D. I. Tishkevichb
Keywords:  hexaferrite, planar loop antenna, dielectric substratum, composite material, power transfer coeffi cient.
Page:  1340

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