|
|
2016 year, number 3
V.F. Kosarev, S.V. Klinkov, and V.N. Zaikovskii
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia E-mail: vkos@itam.nsc.ru
Keywords: radial supersonic jet, cold gas spraying, pressure profile
Pages: 311–318
Abstract >>
The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demon-strated that at the deposition distances lower than 4–6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross sec-tion. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of ls0 ~ 16 gauges
DOI: 10.1134/S086986431603001X
|
V.F. Volkov1, I.I. Mazhul1,2, and V.I. Zvegintsev1
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
E-mail: mazhul@itam.nsc.ru
Keywords: supersonic velocities, wind tunnel, suspension of the model on side pylon, numerical simulation, aerodynamic characteristics
Pages: 319-328
Abstract >>
The possible influence of fastening the models on a side pylon at their tests in wind tunnels on their aerodynamics at supersonic flow speeds has been considered. The physical problem of the pylon and the model interference has been investigated, and the estimates of the pylon influence on integral aerodynamic characteristics have been obtained. The numerical computations of the flow have been done using the averaged Navier-Stokes equations and the SST k-ω turbulence
model in the range of freestream Mach numbers М = 2.5–5. As the investigation
object the “classical” body of revolution of large aspect ratio is considered,
which has a cruciform forward fins and six-blade tail stabilizers.
DOI: 10.1134/S0869864316030021
|
E.-S. Zanoun1,2, E. Onguner3, and C. Egbers3
1American University in Cairo, New Cairo, Egypt
2Benha University, Benha, Egypt
3Brandenburg University of Technology, Cottbus-Senftenberg, Germany
E-mail: elsayed.zanoun@bhit.bu.edu.eg
Keywords: hot wire, pressure probe correction, pipe and channel flows
Pages: 329–342
Abstract >>
This piece of work is concerned with the application of two conventional measuring probes, pressure probe and hot wire, in the wall layer of subsonic ducted, pipe and channel, flows for velocity measurements. Careful measurements have been carried out and analysed accordingly for Reynolds number range of 2.8x105≤Rem≤4.5x105 and 4x104≤Rem≤2.3x105 for the pipe and the channel, respectively. Pressure probes of outer diameters (d0+= d0xur /ν) 20-120 wall units and hot wire, having wire length (l+= l uτ /ν) of 50-250 for the current Reynolds range, have been utilized to carry out the present measurements. When the pressure probe was applied in the wall layer, the wall proximity and the shear gradient played major roles of its incorrect velocity readings, however, this effect was far from being influencing the hot-wire velocity measured in the overlap region. When the pressure probe results compared to those obtained by the hot wire, the pressure probe's data showed hump in the normalized mean velocity profiles around the wall distances y+≤300 and y+≤150 for the pipe and the channel, respectively. Available corrections are adopted and applied to the pressure probe data measured, yielding results that are comparable to those of the hot wire and this was also demonstrated by comparing the present results corrected to the so-called the logarithmic velocity profile.
DOI: 10.1134/S0869864316030033
|
a:2:{s:4:"TEXT";s:64:"G.V. Shoev1,2 and M.S. Ivanov1†";s:4:"TYPE";s:4:"html";}
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
E-mail: shoev@itam.nsc.ru
Keywords: three-shock configuration with a negative reflection angle, nonuniqueness of the numerical solution of the Navier–Stokes equations, transition between regular and Mach reflection, dual solution domain, viscous effects, interaction of shock waves with an expansion fan
Pages: 343–354
Abstract >>
Specific
features of shock wave interaction in a viscous heat-conducting gas with a low
ratio of specific heats are numerically studied. The case of the Mach reflection of shock waves with a negative
angle of the reflected wave with respect to the free-stream velocity vector is
considered, and the influence of viscosity on the flow structure is analyzed.
Various issues of nonuniqueness of the shock wave configuration for different
Reynolds numbers are discussed. Depending on the initial conditions and
Reynolds numbers, two different shock wave configurations may exist: regular
configuration interacting with an expansion fan and Mach configuration. In the dual
solution domain, a possibility of the transition from regular to the Mach
reflection of shock waves is considered.
DOI: 10.1134/S0869864316030045
|
I.K. Gimaltdinov1, R.R. Arslanbekova2, and T.M. Levina1
1Ufa State Petroleum Technical University, Ufa, Russia
2Sterlitamak branch of the Bashkiria State University, Sterlitamak, Russia
E-mails: iljas_g@mail.ru, regina_arslanbekova@mail.ru
Keywords: postdetonation wave, bubbly liquid, bubbles with explosive gas
Pages: 355–367
Abstract >>
We
present the results of numerical investigations of the parameters of postdetonation
waves forming at a passage from the zone occupied with
a bubbly liquid formed by the detonation wave to a zone filled with a liquid
without bubbles. The dependence of the pressure amplitude of detonation waves
and postdetonation waves on the gas volumetric content of bubbles has been
studied. A possibility of the detonation
transfer through the layer of a bubble-free liquid separating the regions of
the bubbly liquid has been shown, the map of possible situations at the detonation
transfer through the layer of this liquid has been presented.
DOI: 10.1134/S0869864316030057
|
S.M. Dmitriev, D.V. Doronkov, M.A. Legchanov, A.N. Pronin, D.N. Solncev, V.D. Sorokin, and A.E. Hrobostov
Nizhny Novgorod State Technical University named after R.E. Alekseev, Nizhny Novgorod, Russia E-mail: nevid000@mail.ru
Keywords: core, fuel rod assembly (FA), spacer grid, flow friction coefficient, hydrodynamics of coolant
Pages: 369–378
Abstract >>
The results of
experimental investigations of local hydrodynamics of a coolant flow in fuel
rod assembly (FA) of KLT-40C
reactor behind a plate spacer grid have been presented. The investigations were
carried out on an aero-dynamic rig using the gas-phase diffusive tracer test.
An analysis of spatial distribution of absolute flow velocity projections and
distribution of tracer concentration allowed specifying a coolant flow pattern
behind the plate spacer grid of the FA. On the basis of obtained experimental
data the recommendations were provided to specify procedures for determining
the coolant flow rates for the programs of cell-wise calculation of a core zone
of KLT-40C
reactor. Investigation results were accepted for the practical use in JSC “OKBM
Afrikantov” to assess heat engineering reliability
of cores of KLT-40C
reactor and were included in a database for verification of CFD programs
(CFD-codes).
DOI: 10.1134/S0869864316030069
|
O.N. Kashinsky1, P.D. Lobanov1, A.S. Kurdyumov1, and N.A. Pribaturin1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Nuclear Safety Institute RAS, Moscow, Russia
E-mail: lobanov@itp.nsc.ru
Keywords: liquid-metal coolant, non-isothermal mixing, experiment, temperature profiles
Pages: 379–382
Abstract >>
The results of
experimental studies on the structure of the temperature field in the tube
cross section at the flow of liquid-metal coolant in a T-shaped mixer are
presented. Experiments were carried out using the Rose alloy as the working
fluid. To determine temperature distribution on the test section wall, infrared
thermography was used; to determine temperature distribution in the channel
cross section, a mobile thermocouple was used. Considerable temperature
maldistribution in the mixing zone of liquid flows with different temperatures
on the tube wall and in the coolant melt is shown.
DOI: 10.1134/S0869864316030070
|
T. Javed, A. Ghaffari, and H. Ahmad
International Islamic University, Islamabad, Pakistan
E-mail: abuzar.iiui@gmail.com
Keywords: MHD, oblique stagnation point, heat transfer, numerical solution
Pages: 383–391
Abstract >>
The unsteady stagnation point flow impinging obliquely on a flat plate
in presence of a uniform applied magnetic field due to an oscillating stream has been studied.
The governing partial differential equations are transformed into dimensionless
form and the stream function is expressed in terms of Hiemenz and tangential
components. The dimensionless partial differential equations are solved
numerically by using well-known implicit finite difference scheme named as
Keller-box method. The obtained results are compared with those available in
the literature. It is observed that the results are in excellent agreement with
the previous studies. The effects of pertinent parameters involved in the problem
namely magnetic parameter, Prandtl number and impinging angle on flow and heat
transfer characteristics are illustrated through graphs. It is observed that
the influence of magnetic field strength increases the fluid velocity and by
the increase of obliqueness parameter, the skin friction increases.
DOI: 10.1134/S0869864316030082
|
G.V. Kuznetsov and A.E. Nee
Tomsk National Research Polytechnic University, Tomsk, Russia E-mail: nee_alexander@mail.ru
Keywords: conjugate heat transfer, numerical modeling, natural convection, turbulence, Baldwin-Lomax model, gaseous infrared radiator
Pages: 393–401
Abstract >>
The mathematical modeling
of the conjugate heat transfer in a closed rectangular region has been carried
out under the conditions of the radiation supply of energy. The temperature and stream function fields
obtained by the modeling illustrate a substantially unsteady nature of
the conjugate heat exchange process under study. An analysis of temperature distributions in typical cross sections of
the solution domain has shown a considerable inhomogeneity of the temperature field. It is found that an increase
in the Rayleigh number leads to substantial modifications of the temperature
and stream function fields. The influence of the distribution of radiation
fluxes over the internal interfaces on the temperature fields and the airflow
character is shown. The influence of the turbulization on the heat transfer intensity near the interfaces between media has
been estimated. Comparisons of the obtained numerical results with experimental
data have shown their good agreement
DOI: 10.1134/S0869864316030094
|
Mitiku Daba and P. Devaraj
Anna University, Chennai, India E-mail: mitbru2007@yahoo.com, devaraj@annauniv.edu
Keywords: unsteady boundary layer, nanofluid, Brownian motion, Keller-box method, stretching sheet, thermophoresis, thermal radiation
Pages: 403–413
Abstract >>
In this paper, we investigated numerically an unsteady boundary layer flow of a nanofluid over a stretching sheet in the presence of thermal radiation with variable fluid properties. Using a set of suitable similarity transformations, the governing partial differential equations are reduced into a set of nonlinear ordinary differential equations. System of the nonlinear ordinary differential equations are then solved by the Keller-box method. The physical parameters taken into consideration for the present study are: Prandtl number Pr, Lewis number Le, Brownian motion parameter Nb, thermophoresis parameter Nt, radiation parameter Nr, unsteady parameter M. In addition to these parameters, two more new
parameters namely variable thermophoretic diffusion coefficient parameter ε and
variable Brownian motion diffusion coefficient parameter β have been introduced
in the present study. Effects of these parameters on temperature, volume
fraction of the nanoparticles, surface heat and mass transfer rates are
presented graphically and discussed briefly. To validate our method, we have
compared the present results with some previously reported results in the literature.
The results are found to be in a very good agreement.
DOI: 10.1134/S0869864316030100
|
V.V. Cheverda1,3, I.V. Marchuk1,2, A.L. Karchevsky2,4, E.V. Orlik3, and O.A. Kabov1,3
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
3Tomsk Polytechnic University, Tomsk, Russia
4Sobolev Institute of Mathematics SB RAS, Novosibirsk, Russia
E-mail: slava.cheverda@gmail.com
Keywords: liquid rivulet, local heating, contact wetting line
Pages: 415–420
Abstract >>
Heat transfer at rivulet water flow over the constantan foil with the length of 80 mm, width of 35 mm, and thickness of 25 mm was studied experimentally. The foil surface temperature was measured by an IR-scanner. Distributions of heat flux density on the surface of the foil, where the liquid flowed, were obtained. To determine the heat flux density from the foil to liquid near the contact line, the Cauchy problem was solved for the stationary heat equation using the thermographic data. Calculation results showed that the maximal heat flux occurs in the area of the contact line and exceeds the average heat flux from the entire foil surface by several times. This is explained by the influx of heat from the periphery of foil to the rivulet due to the relatively high value of heat conductivity coefficient of the foil material and high evaporation rate in the region of the contact line.
DOI: 10.1134/S0869864316030112
|
Yu.B. Zudin
a:2:{s:4:"TEXT";s:93:"National Research Centre “Kurchatov Institute”, Moscow, Russia
E-mail: yzudin@gmail.com";s:4:"TYPE";s:4:"html";}
Keywords: mixing model, kinetic problems, evaporation, condensation, linear approximation, pressure and temperature jumps, abnormal and normal regimes of condensation
Pages: 421–433
Abstract >>
The mixing model was used for analysis of linear kinetic problems of phase tran-sition. The asymmetry of evaporation and condensation, which occurs for intensive processes, remains even for the case of linear approximation. The analytical solution for kinetic jumps of pressure and temperature at the condensed phase surface was obtained: it complies with the results of the classical linear theory. The key result of this study is analytical solution for dependency of pressure jump (condensation) on the temperature factor. This dependence has a minimum near the margin between the abnormal and normal regimes of condensation.
DOI: 10.1134/S0869864316030124
|
S. Munawar1,2, N. Saleem3, and A. Mehmood4
1University of Dammam, Dammam, Saudi Arabia 2University of Management and Technology, Lahore, Pakistan 3Prince Mohammad Bin Fahd University, Alkhubar, Saudi Arabia 4International Islamic University Islamabad, Pakistan E-mail: sufian.munawar@hotmail.com
Keywords: swirling flow, stretching cylinder, entropy generation, heat transfer
Pages: 435–444
Abstract >>
In the present work, the entropy generation due to the heat transfer and fluid friction irreversibility is investigated numerically for a three-dimensional flow induced by rotat-ing and stretching motion of a cylinder. The isothermal boundary conditions are taken into account for the heat transfer analysis. The similarity transformations are utilized to convert the governing partial differential equations to ordinary differential eq-uations. Resulting nonlinear differential equations are solved using a numerical scheme. Expressions for the entropy generation number, the Nusselt number and the Bejan number are obtained and discussed through graphs for various physical parameters. An analysis has been made to compare the heat transfer irreversibility with fluid friction irreversibility using the expression of the Bejan number. It is found that the surface is a durable source of irreversibility and the curvature of cylinder is to enhance the fluid friction irreversibility.
DOI: 10.1134/S0869864316030136
|
S.V. Khasbulatov1, A.A. Pavelko1, L.A. Shilkina1, L.A. Reznichenko1, G.G. Gadjiev2, A.G. Bakmaev2, M.-R.M. Magomedov2, Z.M. Omarov2, and V.A. Aleshin1
1Research Institute of Physics, Southern Federal University, Rostov-on-Don, Russia 2Amirkhanov Institute of Physics, Dagestan Scientific Center RAS, Makhachkala, Russia E-mail: said_vahaevich@mail.ru
Keywords: multiferroics, rare-earth elements, bismuth ferrite, ceramics, structure, microstructure, dielectric and physical properties
Pages: 445–450
Abstract >>
An extensive study was performed to establish correlations between the crystal structure, the grain composition, and the dielectric and thermophysical properties of high-temperature multiferroics of the Bi1-x Dyx FeO3 type (x = 0.05–0.20). It is shown that a trade-off between the macroresponses in the materials is achieved at x = 0.10; this circumstance permits recommendation of the materials for practical use.
DOI: 10.1134/S0869864316030148
|
a:2:{s:4:"TEXT";s:140:"О.P. Solonenko1, А.V. Smirnov1, А.Е. Chesnokov1, V.А. Poluboyarov2, and А.А. Zhdanok2";s:4:"TYPE";s:4:"html";}
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia 2Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia E-mail: solo@itam.nsc.ru
Keywords: agglomerated particle, magnesium oxide, carbon, carbothermic reduction, magnesium, plasma treatment
Pages: 451–459
Abstract >>
Theoretical estimations are made in order to support the possibility of the non-equilibrium carbothermic reduction of magnesium after the plasma treatment of agglomerated particles-decamicron mechano-composites which consist of uniformly mixed reacting nano- and sub-micron insertions of magnesium oxide and soot with the preset stoichiometric composition. Experimental results are presented to confirm the practical attainability of the process.
DOI: 10.1134/S086986431603015X
|
N.D. Morozkin1 and V.I. Tkachev2
1Bashkir State University, Ufa, Russia 2Birsk Department of the Bashkir State University, Birsk, Russia E-mail: MorozkinND@mail.ru, tvi-vlad@mail.ru
Keywords: temperature field, thermal stresses, finite element method, temperature control
Pages: 461–466
Abstract >>
A three-dimensional problem on the control of furnace temperature during cooling of ceramic products of arbitrary shape with allowance for the constraints on thermal stresses is analyzed. An algorithm for calculating a temperature regime making it possible to avoid the occurrence of fracture and irreversible deformation in the products being cooled is proposed. With the example of cooling of a ceramic holder for a spiral wire, a computational experiment is performed. A temperature regime in which the cooling of the product accomplishes in a certain time without exceeding the admissible values of thermal stresses is identified.
DOI: 10.1134/S0869864316030161
|
A.B. Biryukov and P.A. Gnitiev
Donetsk National Technical University, Donetsk, Ukraine E-mail: paul.gnitiev@mail.ru
Keywords: low-temperature heating, double-sided airflow, air-cooling, heat transfer coefficient
Pages: 467–472
Abstract >>
In this paper, the process of convective heat exchange between the cooling air and the cylindrical solid is experimentally studied in a chamber furnace at double-sided cross-flow around the solid, and the corresponding criterial equation is obtained.
DOI: 10.1134/S0869864316030173
|
|