Volume 89, №1
MECHANOCHEMICAL TREATMENT, STRUCTURAL PECULIARITIES, PROPERTIES, AND REACTIVITY OF SHS SYSTEMS BASED ON NATURAL MATERIALS. 4. PRODUCTION OF SHS CERAMICS BASED ON MECHANOACTIVATED MATERIALS
The present paper considers the influence of mechanochemical treatment of minerals (quartz SiO2, calcite CaCO3, and wollastonite CaSiO3) used as components of the charge mixture for SH synthesis of ceramics with a high level of strength and thermal properties. A positive effect of using various modifi ers in mechanochemical treatment of minerals activating the combustion process has been established. Suitable selection of modifiers provides an increase in the strength of synthesized SHS composites due to the formation in the synthesis products of wollastonite, helenite, anorthite, and aluminum nitride, and the decrease in the heat conductivity is due to the formation of an ultraporous structure of specimens. It has been shown that by varying the composition of the charge from the used natural minerals and the conditions of their mechanochemical treatment with modifi ers, as well as the sizes of the synthesized specimen in the SHS regime, an object with high strength and thermal properties can be obtained.
Author:
Z. A. Mansurov, N. N. Mofa, B. S. Sadykov, Zh. Zh. Sabaev, and A. E. Bakkara
SIMULATION OF THE TWO-DIMENSIONAL GASDYNAMIC, TEMPERATURE, AND CONCENTRATION FIELDS IN AN INJECTION REACTOR OF CHEMICAL VAPOR DEPOSITION FOR SYNTHESIS OF CARBON NANOTUBE ARRAYS
The two-dimensional axisymmetric gasdynamic, concentration, and heat fields arising in an injection reactor of chemical vapor deposition in the process of synthesis of arrays of carbon nanotubes in it from hydrocarbons and organometallic compounds were numerically simulated for the purpose of investigating the features of these fields. It was established that, even in the case of laminar flow of a gas mixture over the surface of a substrate positioned in this reactor, in it there arise vortices introducing a signifi cant heterogeneity into the gas flow. The influence of changes in the gasdynamic and temperature fields in the indicated reactor on the characteristics of an array of carbon nanotubes grown on the surface of the substrate was analyzed. Parametric calculations of the dependences of the velocity of the gas flow, the gas temperature, and the concentration of reagents in the reactor on the hydrocarbon flow rate, the temperature of the process, and the length of the injection needle have been performed. These calculations have shown that the regimes of heating and mixing of reagents in an injection reactor of chemical vapor deposition correspond to those of an ideal-mixing reactor. The results obtained can be used for determining the conditions necessary for the growth of homogeneous arrays of carbon nanotubes with a high rate on the surface of a substrate in a reactor of chemical vapor deposition.
Author:
S. I. Futko, A. D. Chornyi, B. G. Shulitskii, and V. A. Labunov
ON THE TRANSFORMATION OF THE HYDRODYNAMIC STATE OF A GRANULAR BED IN THE COURSE OF NONISOTHERMAL FILTRATION
The process of heating a granular bed by filtering air under conditions of the transition of a fixed bed into a bubbling one has been investigated. A dimensionless relation for calculating the time of heating has been obtained.
Author:
E. A. Pitsukha, Yu. S. Teplitskii, V. A. Borodulya, and A. R. Roslik
Keywords:
fixed aerated bed, minimum fluidization velocity, transition to a fl uidized state, time of heating, nonisothermal filtration
Page:
1
CONVECTIVE-DIFFUSION MODEL OF TRANSFER OF A SEDIMENTING LOW-CONCENTRATION POLYDISPERSE SUSPENSION OF STOKESIAN PARTICLES IN A PLANE CHANNEL. PART I
The authors have developed a convective-diffusion model of sedimentation of solid Stokesian particles from a dispersed phase moving in an ideal-mixing regime in a plane channel as the initial boundary-value problem for the particle size function, whose solution was obtained in analytical form. The mixing coefficient has been found from the hydrodynamic analogy with turbulent viscosity, and the kinetic coeffi cients of settling on "wetted" surfaces have been determined on condition that the particles near the walls lose the convective velocity component but preserve the Brownian and Stokesian components. The obtained calculation results are consistent with the universally accepted ideas of separation of the solid phase of suspensions from flows on the settling surface.
Author:
A. V. Ryazhskikh, A. A. Boger, M. I. Slyusarev, and V. I. Ryazhskikh
Keywords:
polydisperse suspension, convective-diffusion model, distribution function, sedimentation
Page:
10
EXPERIMENTAL STUDY OF THE EFFECTS OF COLLISION OF WATER DROPLETS IN A FLOW OF HIGH-TEMPERATURE GASES
Using high-speed video recording and cross-correlation "tracer" visualization, the authors have investigated the regularities of the processes of collision of water droplets (characteristic parameters: radii 0.025–0.25 mm, velocities of motion 0.5–12 m/s, and relative concentration 0.001–0.0012 m3 of liquid droplets in 1 m3 of the gas) in their motion in a flow of high-temperature (about 1100 K) gases. The characteristic effects of collision of two droplets, at which combined droplets are formed (coagulation occurs) and conditions for spreading or fragmentation of the latter are implemented, have been singled out. The values of the Weber and Reynolds numbers for droplets before and after the collisions have been established. The infl uences of the velocities of motion, the dimensions, and the angles of intersection of mechanical trajectories of droplets on the effects of collisions have been determined.
Author:
D. V. Antonov, R. S. Volkov, G. V. Kuznetsov, and P. A. Strizhak
Keywords:
droplets of a liquid, droplet flow, collision, fragmentation, spreading, high-temperature gases, high-speed video recording
Page:
100
EFFECT OF SURFACE PHENOMENA ON EVAPORATION AND CONDENSATION OF WATER SYSTEMS
Experimental results for the dynamic surface tension, surface electrization, and for the rate of evaporation (condensation) of water systems are presented.
Author:
N. N. Kochurova, O. P. Korotkikh, N. G. Abdulin, E. R. Airapetova, R. R. Karaev, and G. Petzold
Keywords:
dynamic surface tension, temperature inversion, electrization, condensation coeffi cient
Page:
112
MIXED CONVECTIVE FLOW OF AN ELASTICO-VISCOUS FLUID PAST A VERTICAL PLATE IN THE PRESENCE OF THERMAL RADIATION AND CHEMICAL REACTION WITH AN INDUCED MAGNETIC FIELD
The purpose of the study is to investigate the steady, two-dimensional, hydromagnetic, mixed convection heat and mass transfer of a conducting, optically thin, incompressible, elastico-viscous fluid (characterized by the Walters' B' model) past a permeable, stationary, vertical, infi nite plate in the presence of thermal radiation and chemical reaction with account for an induced magnetic field. The governing equations of the flow are solved by the series method, and expressions for the velocity field, induced magnetic field, temperature field, and the skin friction are obtained.
Author:
Utpal Jyoti Das
Keywords:
elastico-viscous fluid, vertical plate, mixed convection, thermal radiation, chemical reaction, induced magnetic field
Page:
117
MATHEMATICAL MODELING OF THE HEAT TRANSFER AND CHEMICAL REACTION OF A SWIRLING FLOW OF A DISSOCIATIVE GAS
The authors give the results of investigations into the heat transfer of a swirling flow reacting to absorb the heat of the gas in a cylindrical channel. The performed analysis shows that the heat transfer grows with the flow swirl near the tube inlet and decreases downstream. To intensify the heat transfer it is necessary to organize the flow so that the region with the dominance of centrifugal forces occupies a major portion of the channel.
Author:
O. V. Matvienko and A. M. Bubenchikov
Keywords:
swirling fl ows, heat transfer, chemical reaction, computational hydrodynamics
Page:
127
SIMULATION OF THE PROCESS OF ODORIZING A NATURAL GAS
A model of odorizing a natural gas is built on the basis of the system of motion of viscous, compressible, heatconducting, two-component medium with account for the odorant diffusion. Calculations of convective and diffusional mixing, in a channel, of a gaseous methane main flow interacting with its side jets containing an odorizing gas has been performed. The regimes of flow at different gas velocities in the main and side channels are considered, and the process of the equalization of the odorant concentration by convective and diffusional mechanisms are considered.
Author:
A. L. Tukmakov, B. R. Mubarakshin, and V. G. Tonkonog
Keywords:
odorization; odorant; natural gas; viscous, compressible, heat-conducting two-component medium; convective and diffusional mixing
Page:
135
EVAPORATION OF WATER DROPLETS IN A HIGH-TEMPERATURE GASEOUS MEDIUM
A numerical solution of the problem of heat and mass transfer in evaporation of a droplet of water moving in a stream of high-temperature (up to 1200 K) gases is done on the basis of a system of nonlinear nonstationary partial differential equations describing conductive and radiative heat transfer in the droplet, as well as composite heat transfer at the ″liquid–gas″ interface. The values of the water evaporation rate have been determined. It is shown that the dependence of the evaporation rate on the droplet surface temperature has a nonlinear character. Characteristic relationships between the convective and radiative heat fluxes on the droplet surface (the radiative flux substantially exceeds the convective one; on decrease in the difference between the gas and droplet surface temperatures the difference between the radiative and convective heat fluxes decreases), the lifetimes (total evaporation) of droplets, as well as of the temperature and concentration of steam and gases in the vicinity of droplets have been determined. The calculated characteristics of the water droplet evaporation under conditions of high temperatures of the gas medium differ considerably from those obtained within the framework of the "diffusional" model of evaporation. A comparison of the results of numerical simulation with the experimental data obtained with the use of high-velocity panoramic optical methods of visualization by ″tracing particles″ is carried out.
Author:
O. V. Vysokomornaya, G. V. Kuznetsov, and P. A. Strizhak
Keywords:
heat and mass transfer, evaporation, droplet, water, gaseous medium, high temperatures
Page:
141
CALCULATION OF THE MELTING PROCESS OF A QUARTZ PARTICLE UNDER LOW-TEMPERATURE PLASMA CONDITIONS
The melting process of a quartz particle under low-temperature plasma conditions has been considered. The melting stages of the quartz particle in an experimental electroplasma plant have been modelled mathematically, and the value of the limiting melting radius of particles has been established.
Author:
V. A. Vlasov, O. G. Volokitin, G. G. Volokitin, UDC 631.365 N. K. Skripnikova, and V. V. Shekhovtsov
Keywords:
low-temperature plasma, electroplasma plant, quartz particle, high-silica melt, mathematical model, heat transfer
Page:
152
USE OF ORIENTED SPRAY NOZZLES TO SET THE VAPOR–AIR FLOW IN ROTARY MOTION IN THE SUPERSPRAY SPACE OF THE EVAPORATIVE CHIMNEY-TYPE TOWER
The present paper considers the problem of upgrading the thermal efficiency of chimney-type evaporative cooling towers due to the rotary motion of the vapor–air flow in the superspray space. To set the vapor–air flow in rotary motion, we propose to use the momentum of the sprayed water. It has been shown that the existing parameters of spray nozzles permit setting up to 30% of the water flow momentum in translatory motion, which is enough for changing considerably the aerodynamics of the vapor–air fl ow in the superspray space and improving the operation of the cooling tower. The optimal angle of axial inclination of the spray cone has been estimated. Recommendations are given and problems have been posed for engineering realization of the proposed technologies in a chimney-type cooling tower
Author:
K. V. Dobrego, V. F. Davydenko, and I. A. Koznacheev
Keywords:
spray cooling tower, optimization of heat transfer, droplet flow
Page:
157
NUMERICAL SIMULATION OF HEAT AND MASS TRANSFER IN AN EJECTION APPARATUS
The results of numerical simulation of heat and mass transfer in an ejection apparatus during condensation of vapor–gas mixture components on cold brine droplets are presented. The local parameters of working flows were determined by solving a system of differential heat transfer equations with account for the hydrodynamic pattern. Calculations were carried out on the assumption that the liquid spray is directed horizontally. The Stefan formula has been derived with reference to a spherical coordinate system. The results of calculation of heat and mass transfer rates with and without regard for steam condensation jointly with hydrocarbon vapors are compared and analyzed. Estimation of the effect exerted by the apparatus and drip pan walls on the general process of heat and mass transfer was carried out. The results of simulation made it possible to quantitatively estimate the infl uence of the adopted thickness of the diffusional boundary layer on the vapor–air mixture cooling effect.
Author:
M. M. Kologrivov and V. P. Buzovskii
Keywords:
contact heat exchanger, heat and mass transfer, condensation, diffusion, ejection apparatus, vapor–gas mixture, brine droplets
Page:
167
MATHEMATICAL MODELING OF THE THERMAL STATE OF AN ISOTHERMAL ELEMENT WITH ACCOUNT OF THE RADIANT HEAT TRANSFER BETWEEN PARTS OF A SPACECRAFT
A methodological approach to determination of the thermal state at a point on the surface of an isothermal element of a small spacecraft has been developed. A mathematical model of heat transfer between surfaces of intricate geometric confi guration has been described. In this model, account was taken of the external fi eld of radiant fluxes and of the differentiated mutual infl uence of the surfaces. An algorithm for calculation of the distribution of the density of the radiation absorbed by surface elements of the object under study has been proposed. The temperature field on the lateral surface of the spacecraft exposed to sunlight and on its shady side has been calculated. By determining the thermal state of magnetic controls of the orientation system as an example, the authors have assessed the contribution of the radiation coming from the solar-cell panels and from the spacecraft surface.
Author:
O. M. Alifanov, A. V. Paleshkin, V. V. Terent′ev, and S. O. Firsyuk
Keywords:
heat transfer by radiation, heat balance, isothermal surface elements, absorptivity, emissivity factor, spacecraft
Page:
179
PROBLEM OF BRIEF INTERACTION OF LIQUID AND AMORPHOUS BODIES
The author has proposed a model of brief interaction of liquid and amorphous bodies with boundary conditions of the third kind in the amorphous body without a convective mass flux. Consideration has been given to the thermophysical aspect of formation of the temperature sensation of a biomedical object (BMO) on contact with the liquid body with a different temperature. The procedure of short measurements in the stage of irregular thermal regime (pulse method) was applied to investigation of thermal activity of various anatomical sections of the BMO skin as a function of its temperature. It has been shown experimentally that thermal activity grows with temperature and is within 640–1800 J/(m2·K·s0.5). The total relative error of the method of thermal-activity measurements amounted to ~5%. It has been proposed that analytical calculation of the surface temperature of the BMO on contact be modeled as a combination of the temperatures in liquid and solid media by using the criterion of moisture-content percentage in the BMO.
Author:
D. S. Simankov
Keywords:
irregular thermal regime, short measurements, thermal activity, liquid, biomedical object, thermal injury
Page:
186
CONVECTIVE-DIFFUSION MODEL OF TRANSFER OF A SEDIMENTING LOW-CONCENTRATION POLYDISPERSE SUSPENSION OF STOKESIAN PARTICLES IN A PLANE CHANNEL. PART II
With the analytical expression for the local particle size distribution function in the case of flow of a low-concentration polydisperse suspension whose dispersed phase moves in a turbulent regime simulated by the ideal-displacement model, the authors have quantitatively assessed the regularities of formation of the fields of mass concentration in the flow over the cross section and along the length of the channel, and also of thicknesses of sediments on the upper and lower "wetted" surfaces and their particle size distribution as functions of the intensity of mixing and the particle size distribution of the suspension.
Author:
A. V. Ryazhskikh, A. A. Boger, M. I. Slyusarev and V. I. Ryazhskikh
Keywords:
polydisperse suspension, mass concentration, local sediment thickness, particle size distribution function
Page:
19
METHOD OF WEIGHTED TEMPERATURE FUNCTION
A method of weighted temperature function is proposed for approximate solution of boundary-value problems of nonstationary heat conduction on the basis of identical-equality systems for the indicated function. This method was investigated in solving symmetric problems formulated in the general form with the first-, second-, and third-kind boundary conditions. The data obtained point to the high efficiency and convergence of the method of weighted temperature function.
Author:
V. A. Kot
Keywords:
heat-conduction equation, approximate method, integral identical equality, boundary function, temperature profile.
Page:
192
MATHEMATICAL MODELING OF THE HEAT TRANSFER AND CONDITIONS OF IGNITION OF A TURBULENT FLOW OF A REACTIVE GAS
Results of investigations into the heat transfer and conditions of ignition of a turbulent flow of a chemically reactive gas have been presented. Approximation formulas have been obtained for determining the critical conditions of ignition of the turbulent fl ow, the length of the prefl ame zone, and the criterion of heat transfer in subcritical and supercritical reaction regimes.
Author:
O. V. Matvienko
Keywords:
turbulent flows, heat transfer, chemical reaction, ignition, computational hydrodynamics
Page:
212
COMPUTATIONAL MODELING OF THE WORKING PROCESS IN THE COMBUSTION CHAMBER FOR CASING-HEAD GAS RECOVERY
The present paper considers problems of computational modeling of the working process in multizone combustion chambers (CC) forming a part of gas-turbine power plants for recovering casing-head and other process gases. To investigate the turbulent flow and combustion, we use the LES method with a Smagorinskii subnet model. Various schemes of feeding components into combustion and dilution zones are considered. A comparison is made between the calculated and experimental data on the temperature in the combustion zone.
Author:
N. L. Bachev, O. A. Betinskaya, and R. V. Bul′bovich
Keywords:
combustion chamber, conservation equations, turbulent combustion model, boundary conditions, discrete analog, excess air factor
Page:
221
TRANSPORT PROPERTIES OF A RAREFIED CH4–N2 GAS MIXTURE
The area of application of the rarefi ed neutral methane–nitrogen gas mixture is considered. Experimental data on the transport properties of this mixture and its components were analyzed and generalized on the basis of molecular-kinetic theory relations with the use of the potentials of pair uniform and cross interactions of CH4 and N2 molecules. The parameters of three spherical symmetric three-parameter m-6 Lennard-Jones interaction potentials with a repulsive branch of varying rigidity were determined with the use of the nonlinear weight method of least squares. Tables of reference data on the viscosity of the indicated mixture and the coefficients of interdiffusion of its components were calculated for the concentration range 0–1 at temperatures 100–1150 K. Estimates of the confidential errors in determining the properties of this mixture have been made with the use of the error matrix of parameters of the indicated potentials. The results of calculations were compared with the corresponding reference data obtained earlier for the CH4–N2 gas mixture.
Author:
L. R. Fokin and A. N. Kalashnikov
Keywords:
gas mixture, interdiffusion coefficient, molecular-kinetic theory, collision integral, interaction potential, confidence error
Page:
249
PERMEABILITY OF HOLLOW MICROSPHERICAL MEMBRANES TO HELIUM
This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption–desorption dependences of the studied sorbents have been obtained, from which the parameters of their specifi c permeability to helium are calculated. It has been established that the physicochemical modifi cation of the original particles exerts a great infl uence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.
Author:
V. N. Zinoviev, I. V. Kazanin, A. Yu. Pak, UDC 539.217.5 A. S. Vereshchagin, V. A. Lebiga, and V. M. Fomin
Keywords:
microspheres, cenospheres, membranes, permeability, helium, separation of gases, membrane-sorption method
Page:
25
OPTIMUM DESIGN OF STRUCTURALLY NONHOMOGENEOUS MATERIALS AND CONSTRUCTIONS WITH REQUIRED PROPERTIES
Based on mathematical modeling and computer simulation, the authors have investigated the problem of optimum design of composite materials and constructions with the required properties of plane and curvilinear symmetries in a variational statement. They have also performed a numerical analysis of their structure. Using the theory of continuation in parameter and structural analysis of differential equations describing the change in the properties of composite constructions, the authors have developed an effi cient procedure of nonlocal optimization of the structure of such constructions with the aim of imparting necessary properties to them.
Author:
E. L. Gusev and V. N. Bakulin
Keywords:
optimum design, nonhomogeneous structures, composite materials, variational statement, Pontryagin maximum principle
Page:
260
DEVELOPMENT AND USE OF A MODIFIED PULSE ELECTROSPINNING SETUP FOR PRODUCING SHORT FIBERS
A brief literature review is given of studies concerning the method of standard electrospinning, which is used for producing long nanofibers. Experimental setups — the first version and the new, modified pulse electrospinning setup — are described. The results of works on producing short fi bers using pulse electrospinning are reported in the present article. Data on short fi bers produced experimentally from such polymers as polymethyl methacrylate and cellulose acetate are presented.
Author:
Y. T. Aliyev, B. M. Dabynov, D. U. Bodykov, U. S. Musabekov, and Z. A. Mansurov
Keywords:
pulse electrospinning, short nanofibers, Taylor cone, cellulose acetate
Page:
265
EVOLUTION OF A TWO-LAYER OXIDE COATING ON THE STEEL SURFACE OF THE PRIMARY COOLANT CIRCUIT IN THE COURSE OF NUCLEAR POWER PLANT OPERATION
An analysis of the laws governing mass transfer in a uniform oxide coating on the surface of a circuit is presented. As a result of calculations, the distribution of the fluxes of magnetite and of the particles of corrosion product suspensions depositing on the surface of the throughput section, as well as the distribution of the fluxes of dissolved iron, emerging from steel, along the length of the hydraulic system of the primary coolant circuit of the BREST-type plant, have been refined. The laws governing the process of mass transfer in the BREST-type primary coolant circuit with account for the oxide coating thickness variable in time have been obtained. The distribution of the thicknesses of the magnetite and spinel layers on the steel surface along the length of the BREST-type circulation loop after 365 days from the start of operation in a nominal regime is shown.
Author:
V. V. Alekseev, E. A. Orlova, F. A. Kozlov, and E. V. Varsee
Keywords:
heat-transfer agent (coolant), mass transfer, admixture, oxygen, oxide, steel, lead
Page:
272
RHEOLOGICAL CONSEQUENCE OF THE BEHAVIOR OF THERMOVISCOELASTIC SUBSTANCES IN THE PRESENCE OF AN INSTANTANEOUS POINT HEAT SOURCE
A two-dimensional generalized thermoviscoelastic dynamic problem in the presence of a heat source is studied. The governing equations are expressed in the Laplace–Fourier transform domain and are solved with the use of the eigenvalue approach. The inversions are done numerically by the Bellman method and Gauss quadrature technique
Author:
Manoj K. Mondal and B. Mukhopadhyay
Keywords:
thermoviscoelasticity, rheological property, vector matrix differential equation, relaxation function
Page:
280
REGULAR THERMAL REGIME AND INFLUENCE OF HEAT AND MASS TRANSFER SIMILARITY CRITERIA ON THE PROCESS OF CONVECTIVE DRYING OF POROUS CERAMICS
The results of investigations of the drying kinetics of porous ceramics on the basis of the regular regime theory are presented. The influence of the main heat and mass transfer criteria on the drying process of porous ceramics has been considered. The main thermophysical characteristics of porous ceramics have been determined
Author:
A. I. Ol′shanskii
Keywords:
heating rate of a moist body, rate of decrease in the moisture content, mean integral temperature, heat and mass transfer similarity criteria
Page:
38
APPLICATION OF MICROWAVES FOR OBTAINING GROUND SOLID FUEL
This paper gives an analytical overview of theoretical and experimental data on the microwave grinding of coal. As a result of the work done, we have substantiated the urgency of microwave treatment (MWT) of coal for obtaining ground coal, which in turn has a positive effect on the operation effi ciency of TPPs. Moreover, we have considered the positive effects of microwave grinding as applied to coke.
Author:
Vl. V. Salomatov, S. É. Pashchenko, S. O. Sladkov, and Vas. V. Salomatova
Page:
50
PULSE METHOD OF MASS TRANSFER INTENSIFICATION IN ELASTIC CHANNELS
The kinetics of internal mass transfer in the course of evaporation of liquids in elastic capillary systems in which the transverse dimensions of the pores can both decrease and increase on exposure to intense thermal effect is investigated. Structural transformations in a material arise as a result of its dehydration. It is assumed that the channel radius changes simultaneously over the entire length, synchronously with the interface motion. Three schemes are possible in principle: a uniform change during the process, a faster change in the initial stage, and, conversely, a faster change in the closing stage. The time-limited additional thermal effect during the period that makes the main contribution to the overall duration of the process is capable of substantially enhancing mass transfer with minimum energy consumption.
Author:
V. L. Malyshev
Keywords:
mass transfer, elastic channels, thermal effect
Page:
66
VERIFICATION OF THE SHEAR-STRESS TRANSFER MODEL AND ITS MODIFICATIONS IN THE CALCULATION OF A TURBULENT FLOW AROUND A SEMICIRCULAR AIRFOIL WITH A ZERO ANGLE OF ATTACK
A comparative analysis of different versions of the Menter shear-stress transfer model, including with correction for the curvature of streamlines, has been performed as applied to a periodic flow around a semicircular airfoil with a zero angle of attack at Re = 45,000. A comparison of the calculated aerodynamic coefficients Cx and Cy and the surface distribution of the pressure coefficient, averaged over the period of oscillations of the lift coefficient Cy, with the corresponding experimental data has shown that the Menter shear-stress transfer model modifi ed within the framework of the Rody–Leshtsiner–Isaev approach with the use of the inverse function of the Richardson number correcting the eddy viscosity of a fl ow with a semiempirical Isaev–Kharchenko–Usachov constant equal to 0.02 is preferred compared to the other versions of this model. The errors of the calculations performed with the use of the multiblock computational technologies based on intersecting structured meshes of different scales were analyzed. The interrelation between the evolution of the structure of the periodic flow around the semicircular airfoil and the distribution of its integral force characteristics in the period of Cy oscillations is discussed.
Author:
S. A. Isaev, P. A. Baranov, Yu. V. Zhukova, E. I. Kalinin, and J. J. Miaud
Keywords:
vortex aeromechanics, periodic process, semicircular airfoil, Menter model of shear-stress transfer
Page:
73
MODELING OF THE INTERACTION OF AN UNDERWATER SHOCK WAVE AND AN OBSTACLE IN THE PRESENCE OF A BUBBLE SCREEN
The author has described a modifi ed Godunov method intended to integrate hyperbolic equations of a generalized equilibrium model in divergent form. With the indicated method, the author has investigated the problem of interaction of an underwater shock wave and an obstacle in the presence of a bubble screen
Author:
V. S. Surov
Keywords:
one-velocity multicomponent mixture, hyperbolic system of equations, Godunov method, linearized Riemannian solver, mathematical modeling
Page:
90