Volume 90, № 1

APPLICABILITY OF SEPARATION POTENTIALS TO DETERMINING THE PARAMETERS OF CASCADE EFFICIENCY IN ENRICHMENT OF TERNARY MIXTURES

The separation potentials suggested by various researchers for separating multicomponent isotopic mixtures are considered. An estimation of their applicability to determining the parameters of the efficiency of enrichment of a ternary mixture in a cascade with an optimum scheme of connection of stages made up of elements with three takeoffs is carried out. The separation potential most precisely characterizing the separative power and other effi ciency parameters of stages and cascade schemes has been selected based on the results of the estimation made.
Author:  V. A. Palkin and I. S. Igoshin
Keywords:  separation theory, enriching cascades, separating elements, separation potential, multicomponent mixture
Page:  1

TEMPERATURE FIELD OF TURBULENT FLOW IN A WELL WITH ACCOUNT FOR THE DEPENDENCE OF THERMAL CONDUCTIVITY COEFFICIENT ON TEMPERATURE

A method of solving the problem on nonstationary heat transfer of turbulent fl ow with variable coeffi cients and nonlinearity caused by the dependence of the thermal conductivity of oil on temperature is considered. The method consists of the joint application of the asymptotic methods of small and formal parameters. Based on the analysis of experimental data on the dependence of the thermal conductivity coeffi cient on temperature, it is shown that this dependence can be presented by a linear function in the form of the Taylor series containing the small parameter. The expansion of the problem in the small parameter leads to a linear problem in zero approximation that can be solved by using the asymptotic method of formal parameter. To determine the fi rst coeffi cient of the expansion in the small parameter, a unique procedure of uncoupling has been developed. Analytical dependences of temperature in a well and in the surrounding rocks on time and spatial coordinates have been found that account for the orthotropy of the thermophysical properties of the media.
Author:  A. I. Filippov, A. B. Shabarov, and O. V. Akhmetova
Keywords:  heat transfer, temperature field, turbulent fl ow, asymptotic method, variable coefficients
Page:  9

ON THE INFLUENCE OF PARTICLE ENTRAINMENT FROM AN INHOMOGENEOUS FLUIDIZED BED ON THE HYDRODYNAMICS OF THE VORTEX OVER-BED ZONE

Experimental investigation of the radial distributions of tangential air velocity and total pressure in the vortex overbed zone of a fl uidized bed of diameter 0.393 m has been carried out. The infl uence of the entrainment of particles from the bed in the exhaust trails of gas bubbles on the maximum values of tangential velocity and total pressure has been established.
Author:  E. A. Pitsukha and Yu. S. Teplitskii
Keywords:  fluidized bed, vortex zone, gas bubble, exhaust trail of a bubble, particle entrainment, tangential velocity of air, total pressure
Page:  19

SIMULATION OF THE ACTION OF A SHOCK WAVE ON TITANIUM ALLOY

The laws and mechanism of fracture of coarse-grain and ultrafi ne-grain titanium under shock-wave loading has been investigated. For the shock wave generator a "SINUS-7" accelerator emitting a nanosecond relativistic highcurrent electron beam was used. To test the high-velocity impact at velocities of the order of 2500 m/s, a ballistic installation of caliber 23 mm was used. The mathematical simulation of the high-velocity interaction was carried out with account for the fracture, the phase transitions, and the dependence of the strength characteristics of materials on the internal energy within the framework of continuum mechanics. For both granular structures the general laws and features of the fracture have been established.
Author:  S. A. Afanas'eva, N. N. Belov, V. V. Burkin, UDC 538.91:539.3 E. F. Dudarev, A. N. Ishchenko, K. S. Rogaev, A. N. Tabachenko, M. V. Khabibullin, and N. T. Yugov
Keywords:  shock-wave loading, mathematical and experimental simulation, titanium, ultrafi ne-grain and coarsegrain structures
Page:  24

MOISTURE SORPTION ISOTHERMS AND PROPERTIES OF SORBED WATER OF NEEM (Azadirichta indica A. Juss) KERNELS

A neem tree growing abundantly in India as well as in some regions of Asia and Africa gives fruits whose kernels have about 40–50% oil. This oil has high therapeutic and cosmetic qualities and is recently projected to be an important raw material for the production of biodiesel. Its seed is harvested at high moisture contents, which leads to high post-harvest losses. In the paper, the sorption isotherms are determined by the static gravimetric method at 40, 50, and 60^o C to establish a database useful in defi ning drying and storage conditions of neem kernels. Five different equations are validated for modeling the sorption isotherms of neem kernels. The properties of sorbed water, such as the monolayer moisture content, surface area of adsorbent, number of adsorbed monolayers, and the percent of bound water are also defi ned. The critical moisture content necessary for the safe storage of dried neem kernels is shown to range from 5 to 10% dry basis, which can be obtained at a relative humidity less than 65%. The isosteric heats of sorption at 5% moisture content are 7.40 and 22.5 kJ/kg for the adsorption and desorption processes, respectively. This work is the fi rst, to the best of our knowledge, to give the important parameters necessary for drying and storage of neem kernels, a potential raw material for the production of oil to be used in pharmaceutics, cosmetics, and biodiesel manufacturing.
Author:  M. C. Ngono Mbarga, D. Bup Nde, A. Mohagir, C. Kapseu, and G. Elambo Nkeng
Keywords:  sorption isotherm, modeling, neem, critical moisture content
Page:  35

DETERMINATION OF THE PRESSURE FIELD IN A RESERVOIR-DEFORMED BED EXPOSED TO VIBROWAVES

On the basis of theoretical investigations, the authors have determined the pressure fi eld in a deformable bed exposed to vibrowaves. A study has been made of the propagation of various forms of elastic waves in a deformable bed. An analytical expression has been obtained for the bottom-hole pressure with account of the deformation of the bed′s reservoir. It has been shown that the degree of attenuation of elastic waves in beds with deformable reservoirs increases strongly compared to undeformable ones.
Author:  É. M. Abbasov and N. A. Agaeva
Keywords:  filtration, deformation, Kirchhoff transformations, vibrowave action, differential equation, Bessel function, deformable reservoir, elastic waves
Page:  43

COMPUTER SIMULATION AND OPTIMIZATION OF THE PROCESS OF THAWING OF GROUNDS USING MICROWAVE ENERGY

In this article, consideration is given to a mathematical model and a numerical method to calculate and optimize the process of high-speed thawing of grounds using microwave energy. Relevant examples of calculations and an analysis of results are presented.
Author:  S. A. Nekrasov and V. S. Volkov
Keywords:  thawing, ground, microwave energy, simulation, optimization
Page:  50

MODELING OF THE DYNAMICS OF BURNING A GRANULE OF CARBONATE MINERAL

Thermophysical processes occurring during the thermal decarbonization of natural carbonate minerals (limestones, magnesites) have been investigated. A new model of the working process of burning a single spherical carbonate granule in the form of a system of ordinary differential equations has been proposed. This system makes it possible to generalize, in a natural manner, the model to the multidimensional and nonstationary cases where a moving mass of loose material is described. A comparison of the numerical calculations of the decarbonization dynamics and the measurement results obtained under totally controlled laboratory conditions has proved the high accuracy of the proposed model
Author:  A. V. Savin, A. A. Moiseev, and P. G. Smirnov
Keywords:  carbonate material, thermal decarbonization, Arrhenius kinetics, activation energy
Page:  59

ON THE INFLUENCE OF BOUNDARY CONDITIONS IN MODELING HEAT TRANSFER IN SOIL

A procedure to determine the thermal diffusivity of soils, which is based on the heat-transfer equation, has been developed. Experimental investigations were carried out to establish the influence of boundary conditions on the soil surface on the solution of inverse problems of modeling of heat transfer in soil. On the basis of these data, the author has calculated thermal diffusivity in soils with the proposed methods developed for the case with one and two harmonics and a comparison of these methods has been made; the calculated characteristics and experimental results have also been compared.
Author:  F. D. Mikailsoy
Keywords:  transfer of heat, soil, modeling, boundary conditions, thermal conductivity of soil, thermal diffusivity
Page:  67

NUMERICAL MODELING OF HEAT AND MASS TRANSFER PROCESSES IN THE TRANSFER OF SPENT NUCLEAR FUEL FROM "WET" TO "DRY" CASK STORAGE

The paper describes in brief the heat and mass transfer processes in the transfer of spent nuclear fuel of the RBMK100 reactor from "wet" to "dry" cask storage. The algorithms are described and the results are presented of the "through" calculation of the heat and mass transfer processes in ampoules and in a metal–concrete cask at various stages of spent nuclear fuel management.
Author:  Yu. E. Karyakin, A. A. Pletnev, and E. D. Fedorovich
Keywords:  nuclear power plant, spent nuclear fuel, metal–concrete cask, vacuum drying, long-term storage of casks, computational modeling
Page:  80

EXPERIMENTAL INVESTIGATIONS OF HEAT TRANSFER THROUGH MULTIPLE GLASS UNITS WITH ACCOUNT FOR THE ACTION OF EXTERIOR FACTORS

A technique of processing test data with account for the continuous action of climatic factors on heat transfer of glass-reinforced plastics is suggested.
Author:  B. I. Basok, A. I. Nakorchevskii, S. M. Goncharuk, and L. N. Kuzhel′
Keywords:  climatic factors, multiple glass unit, heat flux, heat transfer
Page:  88

SYSTEM FOR COOLING OF ELECTRONIC COMPONENTS

Results of computational and experimental investigations of heat pipes having a predetermined thermal resistance and a system based on these pipes for air cooling of electronic components and diode assemblies of lasers are presented. An effi cient compact cooling system comprising heat pipes with an evaporator having a capillary coating of a caked copper powder and a condenser having a developed outer fi nning, has been deviced. This system makes it possible to remove, to the ambient air, a heat flow of power more than 300 W at a temperature of 40–50^oC.
Author:  L. L. Vasil′ev Jr., L. P. Grakovich, L. A. Dragun, UDC 536.24 A. S. Zhuravlev, V. A. Olekhnovich, and M. I. Rabetskii
Keywords:  heat pipe, evaporator, condenser, cooling, electronic components
Page:  95

TEMPERATURE OF HEATING AND COOLING OF MASSIVE, THIN, AND WEDGE-SHAPED PLATES FROM HARD-TO-MACHINE STEELS DURING THEIR GRINDING

Grinding of fl at parts occurs by solid abrasive particles due to the physicomechanical process of deformation and to the action of a process liquid at high temperatures in a zone small in volume and diffi cult for observation. The rate of heating and cooling depends on the change in the intensity of the heat fl ux and in the velocity and time of action of the heat source. A study has been made of the regularities of the infl uence of each of these parameters on the depth and character of structural transformations during the grinding of fl at parts from hard-to-machine steels. A procedure to calculate temperature in grinding massive, thin, and wedge-shaped parts has been developed with account taken of the geometric and thermophysical parameters of the tool and the treated part, and also of cutting regimes. The procedure can be used as a constituent part in developing a system for automatic design of the technological process of grinding of flat surfaces. A relationship between the temperature in the grinding zone and the regimes of treatment has been established which makes it possible to control the quality of the surface layer of massive, thin, and wedge-shaped plates from hard-to-machine steels. The rational boundaries of shift of cutting regimes have been determined.
Author:  V. B. Dement′ev, T. N. Ivanova, and A. M. Dolginov
Keywords:  flat parts, hard-to-machine steels, temperature, plate thickness, strip source.
Page:  102

NUMERICAL SIMULATION OF A THERMAL-PROTECTION ELEMENT OF A PROMISING REUSABLE CAPSULE-TYPE LANDER

An indestructible multilayer thermal-barrier coating is proposed for a promising reusable capsule-type lander. This coating is based on a porous carbon-ceramic material. The thermal state of the coating proposed was simulated mathematically for different types of its reinforcement and different values of the porosity and the heat-conductivity coeffi cient of the carbon-ceramic material. Results of a numerical simulation of the temperature state of an element of the multilayer thermal-barrier coating are presented. On the basis of these data, the thickness and the weight effi ciency of the coating were estimated.
Author:  P. V. Prosuntsov, A. V. Shulyakovskii, and N. Yu. Taraskin
Keywords:  reusable capsule-type lander, thermal protection, carbon-ceramic composite material
Page:  110

COMPARATIVE INVESTIGATION OF THE EFFICIENCY OF ABSORPTION OF SOLAR ENERGY BY CARBON COMPOSITE MATERIALS

This paper presents the results of research on the effi ciency of absorption of solar energy by various carbon materials (soot, carbonized apricot pits and rice husks, and carbon nanotubes in the form of a ″forest″), as well as by composites based on them with inclusions of metal oxide nanoparticles. An analysis of the effi ciency of absorption of solar energy by various carbon materials has demonstrated the advantage of the carbon material from carbonized apricot pits. The results of the comparative investigation of the absorptivity of apricot pits with that of the coating of a production prototype of solar collector are presented.
Author:  N. G. Prikhod′ko, G. T. Smagulova, N. B. Rakhymzhan, S. Kim, B. T. Lesbaev, M. Nazhipkyzy, and Z. A. Mansurov
Keywords:  arbon composite material, soot, carbon nanotubes, carbonized apricot pits, carbonized rice husks, metal oxides, electrospinning, solar collector, effi ciency of absorption of solar energy
Page:  117

DETERMINATION OF THE KINETIC OXIDATION CONSTANTS OF CARBON MATERIALS ON THE BASIS OF ANALYSIS OF EXPERIMENTS ON THEIR ABLATION

A new approach to the determination of the ablation properties of a heat-shield carbon material on the basis of analysis of the results of an experimental investigation of its ablation in the jet of an electric-arc plant in the nonstationary regime has been formulated. Original data on the kinetic constants of oxidation of carbon by atomic oxygen have been obtained.
Author:  V. V. Gorskii, M. G. Koval′skii, and A. A. Olenicheva
Keywords:  ablation of carbon, oxidation, sublimation, nitriding, optimization
Page:  126

ON THE MECHANISM OF INTERACTION OF TWO WATER DROPLETS MOVING SUCCESSIVELY AT A SMALL DISTANCE FROM EACH OTHER IN A HIGH-TEMPERATURE GAS MEDIUM

An experimental study has been made of the macroscopic regularities of travel of two water droplets with initial diameters of 1 to 3 mm with a velocity to 3 m/s through a high-temperature (~1100 K) gas counterfl ow propagating with a velocity no higher than 1.5 m/s. Consideration has been given to successive motion of the two droplets in the gas medium with variation of the initial distance between them in the range 5–30 mm. The hypothesis that the rate of evaporation of the second droplet in the gas counterfl ow is much lower than that of the fi rst droplet has been substantiated experimentally. The physical model of the processes of approach of the droplets and their subsequent coagulation has been formulated
Author:  R. S. Volkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords:  high-temperature gases, water, droplet, group of droplets, evaporation, coagulation
Page:  134

MATHEMATICAL SIMULATION OF THE CRYSTALLIZATION PROCESS IN A CONTINUOUS LINEAR CRYSTALLIZER

A mathematical model of the crystallization of uranium in a continuous linear crystallizer, designed for the crystallization separation of desired products in the processing of an irradiated nuclear fuel, is proposed. This model defi nes the dynamics of growth/dissolution of uranyl nitrate hexahydrate crystals in a nitric acid solution of uranyl nitrate. Results of a numerical simulation of the indicated process, pointing to the existence of stationary conditions in the working space of the crystallizer, are presented. On the basis of these results, the characteristic time of establishment of the stationary regime at different parameters of the process was estimated. The mathematical model proposed was validated on the basis of a comparison of the results of calculations carried out within its framework with experimental data
Author:  S. N. Veselov, V. I. Volk, V. A. Kashcheev,a UDC 621.039.54+19.677 T. V. Podymova, and E. A. Posenitskiy
Keywords:  processing of an irradiated nuclear fuel, crystallization of solution, linear crystallizer, mathematical simulation
Page:  140

SIMULATION OF GAS DETONATION PROPAGATION IN A MEDIUM HAVING VARIABLE CHEMICAL COMPOSITION

Within the framework of a quasi-one-dimensional approximation, a mathematical model of the propagation of a detonation wave in a tube fi lled with explosive gas mixture with spatially variable chemical composition has been formulated, and the respective problem has been solved numerically. The shift in the chemical equilibrium of detonation products as well as the friction and heat removal losses were taken into account. The proposed mathematical model allows one to describe steady-state (of Chapman–Jouguet) and over-compressed detonation regimes.
Author:  E. S. Prokhorov
Keywords:  detonation waves, concentration gradient of chemical substances, detonation products, degree of over-compression, simulation
Page:  151

HYDRODYNAMICS AND HEAT TRANSFER IN THE CASE OF COMBINED FLOW IN A ANNULAR CHANNEL OF SMALL CROSS SECTION

The present work is a continuation of experimental investigations conducted at the Moscow Power Engineering Institute (MPEI) on heat-transfer intensifi cation. Brief descriptions of the working section and structure of intensifi ers are given and their basic geometric parameters are enumerated. New systematized experimental data on the coeffi cients of hydraulic resistance and heat transfer in the regime of single-phase convection are given in an extended range of regime parameters and geometric characteristics of the intensifi ers. Considerable increase in the heat-transfer coeffi cient as a function of the geometric characteristics of the intensifi er has been established experimentally. The values of the relative fi n height, at which these are the maxima of heat transfer and hydraulic resistance, have been established. Calculated dependences for the coeffi cient of hydraulic resistance and heat transfer have been obtained.
Author:  A. T. Komov, A. N. Varava, A. V. Dedov, A. V. Zakharenkov, and É. A. Boltenko
Keywords:  annular channel, heat-transfer intensifi cation, interacting fl ows, twist step, single-phase convection, experimental data, coeffi cient of hydraulic resistance, heat-transfer coefficient.
Page:  160

FEATURES OF CAPILLARY BREAKUP OF A LIQUID JET AT OHNESORGE NUMBERS LARGER THAN UNITY

A theoretical study has been made of the forced capillary breakup of a jet of viscous liquid at a value of the Ohnesorge number larger than unity. The regions of breakup of the jet without the formation of satellites have been determined. The dependences of the dimensions of main and satellite droplets on the wave number have been obtained for different Ohnesorge numbers.
Author:  A. A. Safronov
Keywords:  forced capillary breakup, nonlinear waves.
Page:  167

UPRATING THE FRONTAL THRUST OF A SPHERICAL GAS-DYNAMICAL RESONATOR-PULSE AMPLIFIER

Calculations were carried out with application of current numerical methods and with the use of scientifi ctechnical developments of a gas-dynamical resonator-thrust amplifi er. The possibility of creating an exit device with a resonator for a small-size gas-turbine engine that in fl ight provides for thrust uprating by no less than 6% via gas mass attachment in the pulsating process is shown. In this way the size–mass characteristics of the exit device are preserved in the process.
Author:  V. I. Bogdanov and D. S. Khantalin
Keywords:  resonator-thrust amplifi er, gas-turbine engine (GTE), exit device, attached mass
Page:  176

ON IDENTIFICATION OF FLOW REGIMES IN A POLYSPHERICAL MEDIUM WITH THE USE OF VELOCITY DEPENDENCES FOR THE LOSSES OF HEAD

It is shown that the ″universal″ expressions usually obtainable for the coeffi cient of hydraulic resistance Δp of a bed of granulated (granular) medium and for the magnitude of this resistance in a wide range of Reynolds numbers do not allow one to identify fl ow regimes and critical (transitional) values of Re = [Re] of the changes of regimes. With the use of substantiated approaches to the generalization of data on Δp in a bed of spheres, ″piecewise-linear″ (in logarithmic coordinates) dependences of Δp on Re and the values of [Re] = 60–80 have been obtained. Expressions
are given for Δp that are valid for laminar (Δp ~ Re) and postlaminar (Δp ~ Re1.75) regimes of fl ow. The question as to the role of porosity of the medium in the form of an alternatively considered strong power function (Δp ~ 1/ω4.2) is discussed as the one deserving attention
Author:  D. A. Sandulyak, A. A. Sandulyak, V. A. Ershova, UDC 532.546; 532.685 A. V. Sandulyak, M. A. Kononov, and M. N. Polismakova
Keywords:  polyspherical medium (fi lling), porosity, speed of fi ltration, diameter of spheres, pressure drop, Reynolds number
Page:  181

NONSIMILAR SOLUTION FOR SHOCK WAVES IN A ROTATIONAL AXISYMMETRIC PERFECT GAS WITH A MAGNETIC FIELD AND EXPONENTIALLY VARYING DENSITY

The propagation of a cylindrical shock wave in an ideal gas in the presence of a constant azimuthal magnetic field with consideration for the axisymmetric rotational effects is investigated. The ambient medium is assumed to have the radial, axial, and azimuthal velocity components. The fl uid velocities and density of the ambient medium are assumed to vary according to an exponential law. Nonsimilar solutions are obtained by taking into account the vorticity vector and its components. The dependences of the characteristics of the problem on the Alfven–Mach number and time are obtained. It is shown that the presence of a magnetic fi eld has a decaying effect on the shock wave. The pressure and density are shown to vanish at the inner surface (piston), and hence a vacuum forms at the line of symmetry.
Author:  G. Nath and A. K. Sinha
Keywords:  shock waves, mechanics of fl uids, magnetohydrodynamics, nonsimilar solution, interplanetary medium, star rotation
Page:  187

EXPERIMENTAL STUDY OF THE IGNITION OF SINGLE DROPS OF COAL SUSPENSIONS AND COAL PARTICLES IN THE OXIDIZER FLOW

An experimental study has been made of the process of ignition of single drops of water–coal and organic water– coal suspensions and coal particles heated by the oxidizer flow. The low-temperature (400–600^oC) regime of the initiation of combustion of commensurate (from 1 to 3 mm) drops of water–coal and organic water–coal suspensions and coal particles has been considered. With the use of a high-speed (up to 105 frames/s) video camera and Tema Automative software, the infl uence of the oxidizer temperature, the gas fl ow velocity, the size of suspension fuel drops, and the coal particle size on the conditions and integral characteristics of the induction period has been determined. The ignition delay times and the duration of the combustion process of the investigated fuel samples have been established. The features of the stages of stable low-temperature initiation of combustion have been determined.
Author:  K. Yu. Vershinina, D. O. Glushkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords:  coal, fuel suspension, convective heat exchange, ignition
Page:  198

INITIATION OF COMBUSTION OF A GEL-LIKE CONDENSED SUBSTANCE BY A LOCAL SOURCE OF LIMITED POWER

A physical and a mathematical model of the gas-phase ignition of a gel-like condensed substance, containing a combustible (hydrazine) and an oxidizer (liquefi ed oxygen) in its composition, at a cryogenic initial temperature have been developed. A numerical investigation of the integral characteristics of the interrelated physicochemical processes occurring in the initiation of combustion of such a substance by a typical energy source of limited heat content (an individual small-size particle heated to a high temperature) has been perfumed. The dependence of the delay time of ignition of the indicated substance on the heat content of a local heat source was determined. The minimum values of the main parameters of hot particles (their temperature and sizes), at which the ignition conditions are fulfi lled, were estimated. It is shown that the delay time of ignition of a gel-like condensed substance depends mainly on the initial temperature of an energy source. The characteristic features of the conditions and regimes of initiation of combustion of condensed substances found in different aggregate states (solid, liquid, gel-like) under conditions of their local heating by a heat source of limiting power were analyzed.
Author:  D. O. Glushkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords:  gel-like condensed substance, local energy source, heat and mass transfer, phase transition, mathematical simulation
Page:  206

EXPERIMENTAL STUDY OF THE INFLUENCE OF THE CONCENTRATION OF ORGANIC WATER-COAL FUEL COMPONENTS ON THE INTEGRAL IGNITION CHARACTERISTICS

To enlarge the power raw material base, the processes of stable initiation of combustion of drops of organic watercoal fuels have been investigated. For the main components, we used fi lter cakes (coal processing waste), anthracite, bituminous and brown coals of brands D and B2, water, and spent machine, turbine, and transformer oils. We have established the infl uence of concentrations of components on the minimum (limiting) ignition temperatures of organic water-coal fuels and the ignition delay times of drops of fuel components with initial sizes of 0.25–1.5 mm. Investigations were carried out for oxidizer temperatures of 600–1100 K and its velocities of 0.5–5 m/s characteristic of units, aggregates, and large and small power plants. We have determined the characteristic differences of organic water-coal fuel from water-coal fuel and the close laws of the investigated processes for these fuels
Author:  K. Yu. Vershinina, G. V. Kuznetsov, and P. A. Strizhak
Keywords:  water-coal and organic water-coal fuels, fuel suspension, drop, minimum ignition temperature, ignition delay time
Page:  217

EXPERIMENTAL INVESTIGATION OF THE DEEPENING OF THE COMBUSTION FRONT INTO PEAT LAYERS DIFFERENT IN BOTANICAL COMPOSITION

The deepening of the center of combustion into peat layers of different botanical compositions (pine-cotton grass and grass-sphagnum peats), typical for the Tomsk region, was investigated experimentally. Peats were ignited from a model ground forest fi re initiated by fi ring of a needle-litter layer. As a result of laboratory investigations, the change in the temperature in the bulk of peat samples with time was determined and analyzed, and the rates of their combustion in the horizontal and vertical directions were estimated. It was established that a fi re penetrates deep into a layer of grass-sphagnum peat, containing more than 70% of combustion conductors in its composition, more rapidly as compared to that of pine-cotton grass peat. The rates of combustion of grass-sphagnum peat in the vertical and horizontal directions are larger by 20 and 22%, respectively, than those of pine-cotton grass peat, which is evidently due to the botanical composition of grass-sphagnum peat and the random arrangement of components in its layers.
Author:  D. P. Kasymov
Keywords:  peat, ground forest fi re, center of combustion, needle litter, combustion conductors
Page:  227

FLUCTUATION–DISSIPATION MODEL OF THE OPTICAL INFORMATION TRANSMISSION SYSTEM

Corrosion tests were carried out and experimental data are presented on the characteristics of steam-phase oxidation of fuel-element jackets made from an É110G zirconium alloy and vacuum-melted molybdenum in a temperature range of up to 1400^o C at atmospheric pressure. The shut-down cooling characteristics on repeated fl ooding of model fuel assemblies of large-scale stands with fuel elements simulators having jackets made from various standard materials and those from a promising molybdenum one are compared. It is shown that interaction of steam with zirconium alloy is more intense than with molybdenum. At the present time the data on molybdenum are limited.  
Author:  S. S. Bazyuk, D. S. Kiselev, Yu. A. Kuzma-Kichta, A. A. Mokrushin, N. Ya. Parshin, E. B. Popov, D. M. Soldatkin, and I. I. Fedik
Keywords:  steam–molybdenum reaction, metallographic analysis, evaporation, repeated fl ooding, shut-down cooling
Page:  233

MEASUREMENT OF MICROWAVE PARAMETERS OF A SUPERCONDUCTING NIOBIUM CAVITY

This paper describes a method for direct measurement of the amplitude–frequency characteristics and the Q factor of empty superconducting niobium radio frequency Tesla-type cavities. An automated measuring complex that permits recording the superconductivity effect and measuring high Q values has been developed. Measurements have been made of the Q factors of the investigated objects (the fi rst domestic 1.3-GHz niobium cavities) at a level no lower than 0.1·10⁹ (with a maximum value of ~1.2·10¹⁰) and a level of relative losses lower than ~130 dB (with a minimum factor of ~139.7 dB) at liquid nitrogen temperature.
Author:  N. S. Azaryan, M. A. Baturitskii, Yu. A. Budagov, D. L. Demin, S. E. Dem′yanov, V. A. Karpovich, V. V. Kniga, R. M. Krivosheev, N. V. Lyubetskii, S. I. Maksimov, I. L. Pobol′, V. N. Rodionova, G. D. Shirkov, N. M. Shumeiko, and S. V. Yurevich
Keywords:  steam–molybdenum reaction, metallographic analysis, evaporation, repeated flooding, shut-down cooling
Page:  242

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