Volume 96, №1


MATHEMATICAL MODELING OF FILTRATIONAL SOIL FAILURE IN THE COURSE OF KARST-SUFFOSION PROCESSES

A mathematical model has been developed for filtrational soil failure (suffosion) in the course of karst-suff osion processes. A study has been made of the relationship of filtration processes in soluble fractured rocks and the soils overlying them. An investigation has been conducted into the effects of filtration inhomogeneity of rocks on the specific features of the course of the suffosion processes.  
Author:  V. M. Konyukhov, M. G. Khramchenkov, A. N. Chekalina
Keywords:  fi ltration, suff osion, porosity, karst-suff osion process
Page:  1

ON THE RELATION BETWEEN THE RELATIVE DISPOSITION OF INJECTOR DEVICES AND THE DISPERSIVITY OF THE GENERATED AEROSOL

The results of experimental studies of the dispersivity of an aerosol obtained using two injector devices arranged differently mutually are presented. The dependences of the numerical and volume concentrations of droplets in the aerosol formed in the course of variation of the relative angle of attack of jets on the size of droplets are presented. The limiting initial distances between droplets in the aerosol, at which the sizes of the droplets practically do not change during their free fall, are determined. Based on the research results, recommendations were formulated to ensure predictable distributions of the droplets of liquid in a gaseous medium at different distances from the fire zone.  
Author:  G. V. Kuznetsov, A. O. Zhdanova, I. S. Voitkov, P. P. Tkachenko
Keywords:  aerosol, dispersivity, droplets, injector device, jets
Page:  8

MATHEMATICAL SIMULATION OF THE FORMATION OF THE SECONDARY FRAGMENTS OF LIQUID DROPLETS AS A RESULT OF THEIR COLLISION

A mathematical simulation of the formation of the secondary liquid droplets as a result of the collision of their primary droplets has been performed by the VOF method. The influence of diff erent factors on the conditions of fragmentation of liquid droplets and on their integral characteristics was investigated. The ratios between the surface areas of liquid droplets after and before their collision were calculated. It was established that the ratio between the surface areas of the liquid droplets of equal sizes is smaller than that of the liquid droplets having different sizes and that the centered collision of liquid droplets is most efficient. The critical Weber number of liquid droplets, an increase in which does not cause signifi cant changes in the characteristics of their secondary droplets, was determined.  
Author:  D. V. Antonov, R. M. Fedorenko, P. A. Strizhak
Keywords:  liquid droplets, collisions, secondary fragments, size distribution, free surface, mathematical simulation
Page:  17

HYDRODYNAMIC MODEL AND KINETICS OF DISPERSION OF A SOLID DISPERSE PHASE IN THE PROCESS OF MIXING IN A VISCOUS LIQUID MEDIUM

A hydrodynamic model of the dispersion of the solid particles of pigments in a liquid in an apparatus with a highspeed stirrer (a dissolver) designed for the production of
finely dispersed and readily dispersible pigments, which can be used as a preliminary stage of the dispersion of pigments in a liquid in which their concentration is high, is proposed. The kinetics of dispersion of solid particles in the process of their mixing in a liquid was investigated. It is shown that the time and rate of dispersion of solid particles in a liquid are dependent on the hydrodynamic and technological parameters of the process. Methods of increasing the output of dissolvers are proposed  
Author:  D. V. Elizarov, V. V. Elizarov
Keywords:  mixing, dissipation, dispersion, kinetics, solid particles, shear stress, viscous suspension
Page:  29

ABSOLUTE PERMEABILITY TENSORS OF DIGITAL MODELS OF POROUS MEDIA UNDER VARIOUS BOUNDARY CONDITIONS AND DRIVING FORCES

For the first time, a systematic investigation has been made into the infl uence of external boundary conditions and driving forces of liquid flows in anisotropic porous media on their absolute permeability tensor. The investigations have been perfumed on the basis of numerical simulation of a one-phase flow of an incompressible fluid in a porous space using lattice Boltzmann equations. Consideration has been given to cases when anisotropic porous media have permeability tensors with zero and nonzero nondiagonal components. It has been shown that in the case when a porous medium has a permeability with zero nondiagonal components, and external boundary conditions do not exert a substantial influence on the coefficient of medium permeability measured in the presence of a pressure difference or a bulk force in it. In testing anisotropic porous media having a permeability tensor with nonzero nondiagonal components, the external boundary conditions influenced significantly the filtration characteristics of a medium. It has been established that periodic boundary conditions significantly reduce the sensitivity of filtration characteristics of an anisotropic medium to the type of a driving force compared to nonpermeable external boundary conditions. Anisotropic medium permeability tensors measured at the applied pressure difference are nonsymmetrical in both types of external boundary conditions. It has been found that the permeability tensors of such a medium are symmetrical only under periodic external conditions and in the presence of a driving bulk force.  
Author:  T. R. Zakirov, M. G. Khramchenkov
Keywords:  permeability tensor, anisotropy, mathematical modeling, boundary conditions
Page:  39

ANALYTICAL INVESTIGATIONS OF THE SPECIFIC FEATURES OF FILTRATION PROCESSES IN FORMATIONS AT A LOW SATURATION OF THE DISPLACED PHASE

An analysis of the properties of solutions of the Buckley–Leverett equations describing the process of flooding productive strata has been performed. It has been shown that, apart from the widely known result consisting in the formation of a saturation jump on the front edge of the region of formation fluid displacement, a significant role, in terms of practical use, belongs to the dynamics of formation fluid displacement in the vicinity of the back edge of the displacement region, playing a major part at the late stage of deposits′ development when the saturation of the phase displaced from the formation tends to zero. It has been established that in the case of oil being a wetting phase, i.e. in developing hydrophobic oil reservoirs and also at the late stage of reservoirs′ development with a mixed type of wettability, within the framework of the Buckley–Leverett theory, the back edge of the displacement region remains immobile, in practice, and the maximum level of completeness in oil displacement from the formation does not occur. It has been shown that accounting for the action of capillary forces in modeling filtration processes ensures the mobility of the back edge of the displacement region and, accordingly, complete oil displacement from the formation.  
Author:  A. M. Svalov
Keywords:  Buckley–Leverett equations, displacement region, capillary forces, convective components
Page:  50

STRUCTURIZATION AND EFFECTIVE VISCOSITY OF A NON-NEWTONIAN OIL

An analysis of the behavior of non-Newtonian oils in the process of formation and destruction of their structure with the participation of resinous-asphaltenic materials has been performed. The conditions of formation of coagulation structures and the possibilities of their destruction were determined. A general rheological equation defining the possible behavior of non-Newtonian oils in different cases has been derived, and its effectiveness was substantiated with the use of available experimental data. The dependences of the effective viscosity of non-Newtonian oils on the rate of their shear and the content of resinous-asphaltenic materials in them were constructed. It was established that the asphaltenes, resins, and paraffins, contained in an oil, substantially infl uence its rheological properties and, consequently, the movement of the oil and its transportation  
Author:  G. I. Kelbaliev, D. B. Tagiev, S. R. Rasulov, M. R. Manafov
Keywords:  asphaltenes, resins, structurization, eff ective viscosity, non-Newtonian liquids, rheology, shift
Page:  55

BOILING-UP OF A JET OF SUPERHEATED WATER IN OUTFLOWING THROUGH CHANNELS OF DIFFERENT DIAMETERS

An experimental study has been made of the dynamics of boiling-up of a jet of superheated water in outfl owing through short cylindrical channels of diameters 0.33 and 0.63 mm. The change in the shape of the flashing jet at different degrees of superheating has been tracked. It has been established that upon the transition from the stationary process of outfl ow to a nonstationary one, the opening of the jet is not full. Stepwise changes in the angle of opening of the jet in explosive-boiling up transition at the temperature Ts = 470 K were found. From the experimental data, the author determined the change in the opening angle of the jet of superheated water as a function of the degree of its superheating  
Author:  K. A. Busov
Keywords:  full opening, superheated liquid, explosive boiling-up, cylindrical channel, homogenous nucleation
Page:  64

CONSTRUCTION OF A MATHEMATICAL MODEL OF THE FLOW CHARACTERISTICS OF A MULTIPHASE PIPELINE WITH REGARD FOR THE PHASE TRANSITIONS IN IT

A simulation of the flow of a gas–liquid medium in a multiphase pipeline has been performed for the purpose of diagnostics of its flow characteristics. It was established that, in the case of flow of a gas–liquid medium with phase transitions in such a pipeline, its flow characteristics can be unstable, and this instability manifests itself as a local decrease in the pressure loss in the pipeline  
Author:  F. B. Ismaiylova, G. G. Ismaiylov, É. Kh. Iskenderov, Kh. T. Dzhakhangirova
Keywords:  multiphase pipeline, phase transition, fl ow characteristics, instability
Page:  73

CONTRIBUTION TO THE SEARCH FOR THE OPTIMUM CONDITIONS FOR REDUCING WATER LOSS IN THE COOLING TOWER

A mathematical formulation of the problem of finding the optimal size of water droplets and their initial velocity with restrictions on the cooled water temperature and water losses in the form of steam is given. In the case of free convection, such an optimization problem also becomes a boundary-value eigenvalue problem with a continuous spectrum, where the eigenvalue is the air flow at the cooling tower inlet. To free convection there corresponds the minimum flow value. The solutions are obtained for the initial temperature of the cooled water (70o C) sprayed in the tower with 1.8 kg·m–2 ·s –1. Attention is drawn to the difficulty of assessing the loss of water in the form of microscopic droplets.  
Author:  K. O. Sabdenov, M. Erzada, B. A. Zhakishev
Keywords:  cooling tower, optimal sizes of water droplets, droplet and stream entrainment, mathematical simulation
Page:  79

INVESTIGATING GAS HYDRATE IGNITION AT VARIOUS HEATING SCHEMES

Physical and mathematical models have been developed for ignition of gas hydrates in domination of different heat transfer schemes. A numerical investigation has been made into interrelated processes of heat transfer under the conditions of chemical reaction and exothermal and endothermal phase transformations at the stage of initiating gas hydrates′ combustion. The model has been put through practical evaluation in comparing theoretical results of investigations with experimental data. We have established dependences of the main characteristic of the process, viz., ignition delay time as a function of ambient temperature in variation of the emissivity and heat transfer coeffi cients. We have identifi ed the limit values of the main parameters of an energy source, at which the conditions for ignition occur steadily. The varied parameters (the emissivity and heat transfer coefficients and the heating temperature) cover the technological conditions for a group of applications in power engineering.  
Author:  O. S. Gaidukova, S. Ya. Misyura, P. A. Strizhak
Keywords:  gas hydrates, heating schemes, ignition, ignition delay time, prediction (prognostic) model
Page:  91

MODELING THE PROCESS OF COMBUSTION OF METHANE HYDRATE WITH ALLOWANCE FOR NONEQUILIBRIUM DECOMPOSITION

The authors have proposed a mathematical model of the process of combustion of methane hydrate in an enclosed volume with allowance for the kinetics of its decomposition (nonequilibrium decomposition). Based on numerical solution by the method of large particles, distributions of basic parameters of the system have been constructed. A comparison has been made of the distinctive features of hydrate combustion for the cases of equilibrium decomposition of the gas hydrate and of nonequilibrium decomposition with allowance for the kinetics. It has been shown that within the framework of the model with nonequilibrium decomposition, the intensity of combustion at the beginning of the process is much higher compared to the results of calculating based on the model with equilibrium decomposition. The authors have constructed and analyzed the dependences of the temperature of the flame, the maximum pressure of a gas mixture, and the law of motion of the phase-transition front for the two models of hydrate decomposition.  
Author:  I. M. Bayanov, I. K. Gimaltdinov, and M. V. Stolpovskii
Keywords:  combustion, hydrate, kinetics, nonequilibrium decomposition
Page:  104

MIGRATION ACTIVITY OF HEAVY METALS DURING PYROLYSIS OF DRIED SEWAGE SLUDGE IN A FIXED-BED REACTOR

The results of a study of the pyrolysis of dried sewage sludge taken from a fi xed-bed reactor of urban wastewater treatment plants are presented. The obtained experimental data made it possible to estimate the migration activity of heavy metals entering into the composition of the sewage sludge. Measurements were carried out for vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), strontium (Sr), lead (Pb), rubidium (Rb), barium (Ba), zirconium (Zr), and arsenic (As). It is shown that the emission of heavy metals upon release of volatile substances during pyrolysis is characteristic for almost all of the studied elements, among which As, Rb, Co, and Ba are the elements having the highest migration activity.  
Author:  G. Ya. Gerasimov, V. V. Khaskhachikh, G. A. Sychev, V. M. Zaichenko
Keywords:  sewage sludge, pyrolysis, fi xed-bed reactor, heavy metals, migration activity.
Page:  112

MULTICRITERIA ANALYSIS TO SUBSTANTIATE THE PROMISING NATURE OF USING WASTE AS COMPONENTS OF FUELS

Consideration has been given to the use of municipal and industrial waste as components of a high-moisture suspension fuel. An analysis has been made of the efficiency of such fuel as far as its technical and economic, energy, and environmental indices are concerned with the MCDM multifactor-analysis methods. It has been established that suspensions without impurities and suspensions with a 10% content of cardboard are the most efficient. It has been shown that the fi nal index of efficiency of such suspensions exceeds the effi ciency of coal by 90% in some cases. Directions for raising the effi ciency of suspension fuels whose basic components are industrial waste and municipal solid waste have been determined.  
Author:  G. V. Kuznetsov, G. S. Nyashina, K. Yu. Vershinina, D. S. Romanov, P. A. Strizhak
Keywords:  carbon waste, municipal waste, suspensions, combustion, effi ciency, MCDM multifactor analysis
Page:  120

DETERMINATION OF THE DISTANCE BETWEEN THE DROPLETS OF FIRE-EXTINGUISHING AGENTS IN AN AEROSOL CLOUD AT WHICH THEY DO NOT COLLIDE

Results of experimental investigations of the integral characteristics of the collisions of droplets of fire-extinguishing agents, having a surface tension of 0.0011–0.0014 Pa·s and a viscosity of 0.07269–0.08241 N/m, in an aerosol cloud with a droplet concentration γ d = 0–7.142 L/m3 are presented. The dependence of the number of collisions of such droplets in an aerosol cloud on their Weber number and linear interaction parameter was demonstrated. It was established that the frequency of realization of each of the regime of collisions of extinguishant droplets in an aerosol cloud (rebound, scattering, coagulation, and fragmentation) depends on the sizes of the droplets and their concentration in the cloud. The distances between the extinguishant droplets in an aerosol cloud, at which they do not collide, were determined with regard for the initial sizes of the droplets, the velocities of their movement, and the temperature to which they are heated (T = 20 and 600oC). A general approximate expression has been constructed for estimating the distance between the droplets of diff erent fi re-extinguishing agents in an aerosol cloud, at which these droplets do not collide and, consequently, do not cause signifi cant changes in the dispersivity of the cloud.  
Author:  I. S. Voitkov, A. O. Zhdanova, S. S. Kropotova, G. V. Kuznetsov, P. P. Tkachenko
Keywords:  fi re-extinguishing agents, aerosol, droplets, collisions
Page:  130

CHARACTERISTICS OF A TYPICAL INDOOR SEAT OF FIRE

The paper presents the results of experimental investigations of the main characteristics of a typical indoor seat of fire at the stages of initiating the ignition of combustible materials and in the process of their burning. Wood material, wood fiberboard, linoleum, and plastic panels have been used as combustible materials. We registered the characteristics of the seat of fire, viz., the temperature in the zone of burning of combustible materials, the times of termination of their flame combustion, and thermal decomposition, the concentrations of gaseous products of pyrolysis and combustion of these materials. The possibility of indentifying the material dominating in the seat of fire has been substantiated. Reliable identifi cation of such material makes it possible to optimize the process of suppressing the seat of fire.  
Author:  A. O. Zhdanova, N. P. Kopylov, S. S. Kropotova, G. V. Kuznetsov
Keywords:  seat of fi re, indoor space, combustible materials
Page:  143

INVESTIGATION OF THE MELTING OF SILICATE MATERIALS AS A RESULT OF EXPOSURE TO LOW-TEMPERATURE PLASMA

The paper presents a mathematical model and the results of calculating the process of melting of silicate materials as a result of their exposure to low-temperature plasma. In the case of a low temperature of the gaseous region exceeding insignifi cantly the silicate melting temperature, the phase transition is preceded by a quite long induction period characterized by the material′s heating from the initial temperature to the melting temperature. After the completion of this stage, a melting process begins accompanied by a shift of the interphase boundary deeper into the material. With increase in the initial gas temperature the duration of the induction period decreases. It has been established that the velocity of the melting front propagation is determined by the initial temperature of the gas phase and the thermophysical characteristics of the material but is weakly dependent on the fill layer thickness.  
Author:  O. V. Matvienko, O. G. Volokitin, V. V. Shekhovtsov
Keywords:  silicate materials, heat transfer, melting, Stefan problem, mathematical modeling
Page:  150

SIMULATION OF COMPLEX HEAT TRANSFER DURING CYCLIC DEPOSITION OF A HIGH-TEMPERATURE AEROSOL ON A SUBSTRATE

The paper considers heat transfer during cyclic spraying of a high-temperature aerosol depositing in the form of a condensed phase on a flat plate of fi xed thickness. A cyclically moving boundary appears with an increasing mass of deposited material with the same thermophysical characteristics as the plate. The cycle is equal to the time of application of the aerosol within fractions of a second (heating) and to an order of magnitude longer convective-conductive and radiant cooling. To solve the formulated mathematical model analytically, the linearization of the radiant heat flux was carried out by expanding the temperature difference of the moving boundary in a series in powers without taking into account the radiation and taking it into account with keeping the linear terms and further analyzing the linearization error. Moreover, transformation of the spatial coordinate is applied, allowing one to transform a region with a moving boundary into a region with a fixed boundary. A new analytical solution of a rather complicated problem is obtained by the method of a finite cosine Fourier transform, having previously solved the problem for eigenvalues and eigenfunctions with boundary conditions of the third kind. The results on the thermal state of the entire system with a complex temperature profile on the outer moving boundary are obtained and analyzed.  
Author:  V. F. Formalev, R. A. Degtyarenko, B. A. Garibyan
Keywords:  moving boundary, complex heat transfer, convective-conductive and radiant types of heat transfer, complex relief of a boundary in time, linearization, coordinate transformation, fi nite cosine Fourier transform
Page:  160

THE METHOD OF INTEGRAL TRANSFORMATIONS FOR SOLVING BOUNDARY-VALUE PROBLEMS FOR THE HEAT CONDUCTION EQUATION IN LIMITED AREAS CONTAINING A MOVING BOUNDARY

A method of integral transformations for solving the boundary-value problems for the equation of heat conduction in limited regions containing a moving boundary of phase transition has been developed. New integral representations of the solutions of boundary-value problems for the heat conduction equation under different boundary conditions assigned on the outer fixed boundaries of a limited region are obtained. The analytical expressions obtained by the proposed method for solving the indicated boundary-value problems are convenient for calculating and studying the temperature fi elds, as well as the velocity of motion of the interface at large Fourier numbers  
Author:  V. V. Shevelev
Keywords:  integral transformation, phase transition, heat conduction, interface, limited region
Page:  168

MATHEMATICAL MODELING OF A THERMAL CONVERTER WITH A CYLINDRICAL HEAT PIPELINE AND A LUMPED HEAT SOURCE

Consideration has been given to the issues of a functional scheme and substantiation of the efficiency of thermal converters to monitor the moisture content of a flow of liquid materials. Furthermore, in the work, two basic types of physical models, i.e., with lumped and distributed heat sources, have been identified on the basis of a segment of a pipeline with radial orifices, in which there are cylindrical probes with heating and thermosensitive elements across the liquid-material flow.  
Author:  P. M. Matyakubova, P. R. Ismatullaev, N. I. Avezova, M. M. Mahmudjonov
Keywords:  physical model, fl ow, moisture content, liquid material, thermosensitive element, heating element, pipeline, heat transfer
Page:  178

OPTIMIZATION OF STEAM ASSISTED GRAVITY DRAINAGE IN VERIFIED INTEGRAL SIMULATOR

An integral model of the steam assisted gravity drainage of an oil field has been developed on the basis of the law of conservation of the masses of the phases and the law of conservation of their energy. A verifi cation of the results of calculations performed by this model has been performed, and it was established that they are in satisfactory agreement with the corresponding field data. It is shown that the final oil recovery factor for the Senlac oil field comprises 32% and that the optimization of the development system of the Fengcheng field increases its oil recovery factor by 7%.  
Author:  A. Ya. Gilmanov, K. M. Fedorov, A. P. Shevelev
Keywords:  high-viscosity oil, steam assisted gravity drainage, verifi cation, optimization, steam–oil ratio, oil recovery
Page:  188

PERFORMANCES OF A CYLINDRICAL HEAT PIPE USING FERROFLUID AS THE WORKING LIQUID AT DIFFERENT INCLINATION ANGLES

In this research, the thermal performance of a cylindrical heat pipe filled with a ferrofl uid as the working liquid was tested at different inclination angles: 0, 60, and 90o . The ferrofl uid was synthesized from magnetite particles and water as the base fluid. The heat pipe was manufactured from a copper container, and copper fibers were used as the wick structure inside the heat pipe. The magnetite particles had an average diameter of 13 nm, as was yielded by the transmission electron microscopy (TEM). The zeta potential value (30.25 mV) and visual analysis showed that the ferrofl uid was stable for nine months and could be used as the working liquid in cylindrical heat pipes. The thermal conductivity and specifi c heat of the ferrofl uid were 0.605 W/(m·K) and 4090 J/(kg∙K), respectively. The performances of the heat pipe at diff erent inclination angles allowed the conclusion about a relatively stable thermal resistance and temperature distribution, particularly at a higher heat input of 15 W.  
Author:  N. S. Asri, A. P. Tetuko, M. Ridwan, A. Wicaksana, L. F. Nurdiyansah, E. A. Setiadi, A. M. S. Sebayang, P. Sebayang
Keywords:  magnetite particles, ferrofl uid, cylindrical heat pipe, inclination angle, thermal performance
Page:  197

DESIGN AND PRACTICAL APPLICATION OF THERMAL HUMIDITY CONVERTERS FOR LIQUID MATERIALS

The paper considers quality indicators and morphological tables of the main elements of thermal converters of the moisture content of liquid materials on the basis of which the optimal structure of these converters is selected from the quality indicators, namely, sensitivity, accuracy, reliability, and performance  
Author:  N. I. Avezova, P. M. Matyakubova, P. R. Ismatullaev, S. A. Kodirova
Keywords:  quality, sensitivity, accuracy, reliability, speed, structure, optimal structure, measuring range, heat conductor, heating element
Page:  206

INVESTIGATION OF THE STRUCTURE OF A CEMENT COMPOSITE MODIFIED BY HYDROTHERMAL SiO2 NANOPARTICLES AND MCNT NANOPARTICLES BY THE X-RAY PHASE ANALYSIS METHOD

The x-ray phase analysis method has been used to study the eff ects of small doses of hydrothermal SiO2 nanoparticles and nanoparticles of multiwalled carbon nanotubes (MCNTs) on the structure of a Portland cement composite separately and in a combination at the age from 4 h to 28 days. It has been established that clinker minerals and Portlandite components do not diff er signifi cantly in nanomodifi ed specimens compared to control specimens, which agrees with the thermogravimetrical data for the ages of 1 and 28 days. In the region of the angles 2θ = 5–12 degrees, structural diff erences were identifi ed for the CSH gel in the nanomodifi ed specimens: at the age of 1 day (24 h), there were CSH peaks (I) in the diff raction patterns of the modifi ed specimens with Basel distances of 12.44–12.54 Å between the layers. At the age of 28 days, relatively higher peaks of a tobermorite-like structure were identifi ed with a Basel distance reaching a maximum value of 14.54 Å in a specimen modifi ed by a combination of SiO2 and MCNT nanoparticles. The increase in the Basel distances corresponds to a reduction in the values of the Ca/Si ratio and an improvement in the ordering of the CSH-gel structure and agrees with the IR-spectroscopy data having shown the higher degree of polymerization of silicon–oxygen tetrahedrons in nanomodifi ed specimens.  
Author:  E. N. Polonina, V. V. Potapov, S. A. Zhdanok, S. N. Leonovich
Keywords:  cement composite, SiO2 nanoparticles, MCNTs, x-ray phase analysis, CSH-gel structure, Basel distances, Ca/Si ratio
Page:  215

CERTAIN EXACT SOLUTIONS TO THE PROBLEM OF LIQUID FLOW IN PRISMATIC TUBES

The problems of diff erent sections of physics and mechanics share a mathematical model that is based on the Poisson equation with a constant right-hand side and a zero (constant) value of the sought function on the contour of a two-dimensional region. A set of exact solutions to the formulated problem is presented in the "plane" region of certain form to describe the following problems: flow of a liquid in the channel at small Reynolds numbers; motion of an ideal liquid during the rotation of the contour bounding the region; torsion of a rod; deflection of the membrane at the zero displacement on the boundary of the region; heating of the rod. The possibility to construct approximate solutions for certain cross sections of the channel, etc. by using these exact solutions is noted. Examples are given.  
Author:  A. I. Moshinskii
Keywords:  velocity profi le, channel, dimensionality, opening of the wedge, cavern
Page:  224

SIMULATION OF LARGE VORTICES IN THE FLOW OF AN INCOMPRESSIBLE VISCOUS FLUID AROUND A SPHERE AT REYNOLDS NUMBERS FALLING WITHIN A LARGE RANGE

A simulation of the large vortices, formed in the flow of an incompressible viscous fluid around a sphere at different Reynolds numbers, has been carried out. Dependences of the local and integral characteristics of such a flow on its initial parameters are presented. Results of the numerical calculations performed were compared with the corresponding experimental data and with the available correlation dependences for the drag and heat-transfer coeffi cients of a fluid flow around a sphere.  
Author:  K. N. Volkov, V. N. Emel'yanov, I. V. Teterina
Keywords:  computational fl uid dynamics, simulation, large vortices, sphere, drag, heat transfer
Page:  236

THE CHARACTERISTIC FEATURES OF GAS DYNAMICS AND HEAT TRANSFER OF STATIONARY AND PULSATING FLOWS IN THE INTAKE SYSTEM OF A PISTON ENGINE

Data on gas dynamics and heat transfer of stationary and pulsating flows along the length of the intake system of a piston engine are presented. The studies were carried out on full-scale models of a piston engine for different initial conditions. The infl uence of gas-dynamical nonstationarity on the thermal-mechanical characteristics of flows is shown experimentally. It has been established that the degree of turbulence of pulsating flows is an order of magnitude higher than in a stationary flow, and the intensity of heat emission, on the contrary, is 5–13% less. It is shown that the values of the degree of turbulence tend to decrease (up to 2 times) when air moves along the length of the intake system, and the change in the intensity of heat emission has a parabolic form, which is typical of both stationary and pulsating flows. The results obtained can be used for refi ning engineering methods of calculating the processes of gas exchange and developing the means of improving the intake systems of piston and composite engines  
Author:  L. V. Plotnikov
Keywords:  piston engine, intake system, gas fl ows, gas dynamics, turbulence degree, local heat emission, comparative analysis
Page:  246

NUMERICAL MODEL OF ULTRASONIC AGGLOMERATION OF SUBMICRON PARTICLES IN RESONANT GAS GAPS

Theoretical substantiation of the physical principle of increasing the efficiency of ultrasonic agglomeration of submicron particles is proposed, which is based on the creation of resonant conditions for forming vortex flows in gas gaps. The generated vortex flows lead to a local increase in the concentration of particles, which increases the frequency of collisions and, consequently, the efficiency of agglomeration. A numerical model of this process is proposed. The results of calculations carried out on the basis of the numerical model made it possible to ascertain that the efficiency of agglomeration when creating vibrations by a flexurally oscillating radiator (a collection of vortex flows is formed) is more than four times higher than in the case of creating vibrations using a piston radiator (one little-eff ective vortex flow is generated).  
Author:  V. N. Khmelyov, R. N. Golykh, V. A. Nesterov, A. V. Shalunov
Keywords:  ultrasound, gas cleaning, coagulation, agglomeration, acoustic fi eld, fractional effi ciency, resonant gap, vortex flow
Page:  255

INDIRECT, WITH RESPECT TO THE NONLINEARITY EQUATION, MEASUREMENT OF THE RADIATING CAPACITY AND TEMPERATURE OF OPAQUE MATERIALS

This work is aimed at improving metrological characteristics and expanding the areas of application of optical thermometry of opaque objects, including the method of two-color compensative pyrometry with an apriori averaged adjustment previously developed by the authors. A nonlinearity equation has been obtained that connects the nonlinearity coefficient of spectral distribution of directional emissivity on an average wavelength of the registered radiation with a value of spectral directional emissivity on one of boundary wavelengths via the measured brightness temperature on three wavelengths. It has been established that the number of numerical solutions of the equation at various qualitative and quantitative characteristics of spectral distributions is from 1 to 3. To determine a correct solution, analytical and algorithmic methods of its identification have been proposed. On the basis of the equation, linear, two-range, and parabolic methods of determining spectral directional emissivity have been developed. It has been established that the methodological errors of temperature measurements by the two-range method are 5–7 times lower than the errors of the linear method. For signifi cant nonlinearities, the parabolic method errors are 1.13–1.24 times lower than the linear method errors. In this case, for the two-range method, the combined errors for two-color compensative pyrometry are lower than the errors for spectral ratio pyrometry and for energy pyrometry 110 and 7 times respectively  
Author:  L. F. Zhukov, D. A. Petrenko
Keywords:  nonlinearity equation and coeffi cient, spectral distribution of directional emissivity, object temperature, brightness temperature, parabola
Page:  266

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