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Thermophysics and Aeromechanics

2016 year, number 3

Gas dynamics of a supersonic radial jet. Part II

V.F. Kosarev, S.V. Klinkov, and V.N. Zaikovskii
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: radial supersonic jet, cold gas spraying, pressure profile
Pages: 311318

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 46 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

Numerical simulation of the side pylon effect on the aerodynamic characteristics of models at their wind tunnel tests

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
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 = 2.55. 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

Conventional measuring probes in the wall layer of turbulent subsonic ducted flows

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
Keywords: hot wire, pressure probe correction, pipe and channel flows
Pages: 329342

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

Numerical study of shock wave interaction in steady flows of a viscous heat-conducting gas with a low ratio of specific heats

G.V. Shoev1,2 and  M.S. Ivanov1
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: three-shock configuration with a negative reflection angle, nonuniqueness of the numerical solution of the NavierStokes equations, transition between regular and Mach reflection, dual solution domain, viscous effects, interaction of shock waves with an expansion fan
Pages: 343354

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

Features of the dynamics of postdetonation waves

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
Keywords: postdetonation wave, bubbly liquid, bubbles with explosive gas
Pages: 355367

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

Investigating hydrodynamic characteristics and peculiarities of the coolant flow behind a spacer grid of a fuel rod assembly of the floating nuclear power unit

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
Keywords: core, fuel rod assembly (FA), spacer grid, flow friction coefficient, hydrodynamics of coolant
Pages: 369378

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

Modeling the flow of liquid-metal coolant in the T-shaped mixer

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
Keywords: liquid-metal coolant, non-isothermal mixing, experiment, temperature profiles
Pages: 379382

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

Numerical study of unsteady MHD oblique stagnation point flow and heat transfer due to an oscillating stream

T. Javed, A. Ghaffari, and  H. Ahmad
International Islamic University, Islamabad, Pakistan
Keywords: MHD, oblique stagnation point, heat transfer, numerical solution
Pages: 383391

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

Numerical analysis of thermogravitational turbulent convection in a closed rec-tangular region with radiation source of energy

G.V. Kuznetsov and A.E. Nee
Tomsk National Research Polytechnic University, Tomsk, Russia
Keywords: conjugate heat transfer, numerical modeling, natural convection, turbulence, Baldwin-Lomax model, gaseous infrared radiator
Pages: 393401

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

Unsteady boundary layer flow of a nanofluid over a stretching sheet with variable fluid properties in the presence of thermal radiation

Mitiku Daba and P. Devaraj
Anna University, Chennai, India
Keywords: unsteady boundary layer, nanofluid, Brownian motion, Keller-box method, stretching sheet, thermophoresis, thermal radiation
Pages: 403413

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

Experimental investigation of heat transfer in a rivulet on the inclined foil

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
Keywords: liquid rivulet, local heating, contact wetting line
Pages: 415420

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

Linear kinetic analysis of evaporation and condensation

Yu.B. Zudin
National Research Centre Kurchatov Institute, Moscow, Russia
Keywords: mixing model, kinetic problems, evaporation, condensation, linear approximation, pressure and temperature jumps, abnormal and normal regimes of condensation
Pages: 421433

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

Entropy production in the flow over a swirling stretchable cylinder

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
Keywords: swirling flow, stretching cylinder, entropy generation, heat transfer
Pages: 435444

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

Phase composition, microstructure, and thermophysical and dielectric properties of multiferroic Bi1-xDyxFeO3

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
Keywords: multiferroics, rare-earth elements, bismuth ferrite, ceramics, structure, microstructure, dielectric and physical properties
Pages: 445450

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 = 0.050.20). 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

Non-equilibrium carbothermic reduction of magnesium at the treatment of agglomerated particles magnesium oxide carbon in the plasma jet

.P. Solonenko1, .V. Smirnov1, .. Chesnokov1, V.. Poluboyarov2, and .. Zhdanok2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia
Keywords: agglomerated particle, magnesium oxide, carbon, carbothermic reduction, magnesium, plasma treatment
Pages: 451459

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

Control of the process of cooling of ceramic products with allowance for the constraints on thermal stresses

N.D. Morozkin1 and V.I. Tkachev2
1Bashkir State University, Ufa, Russia
2Birsk Department of the Bashkir State University, Birsk, Russia
Keywords: temperature field, thermal stresses, finite element method, temperature control
Pages: 461466

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

Experimental investigation of convective heat exchange in chamber furnaces at heat treatment of cylindrical solids

A.B. Biryukov and P.A. Gnitiev
Donetsk National Technical University, Donetsk, Ukraine
Keywords: low-temperature heating, double-sided airflow, air-cooling, heat transfer coefficient
Pages: 467472

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