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2018 year, number 1
V.L. Okulov
The Technical Unviersity of Denmark, Lyngby, Denmark Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia E-mail: vaok@dtu.dk
Keywords: rotor aerodynamics, vortex wake behind the rotor, wind power plant, interaction be-tween the rotor and the wake, power loss.
Abstract >>
The aim of the review is to assess the value of model experimental studies for the development of classical rotor aerodynamics as well as to describe the most significant recent results stimulated by intense development of wind power.
DOI: 10.1134/S0869864318010018
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D.V. Platonov1, 2, A.V. Maslennikova2, D.A. Dekterev1,  2, A.V. Minakov1,  2, and A.V. Abramov2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Siberian Federal University, Krasnoyarsk, Russia
E-mail: platonov-08@yandex.ru
Keywords: pressure pulsations, vortex precession, Francis hydroturbine, high-head hydroelectric power station
Abstract >>
In the present study, we
report on the results of an experimental study of pressure pulsations in the
flow duct of a medium-scale hydrodynamic bench with Francis turbine. In various
regimes, integral and pulsation characteristics of the turbine were measured.
With the help of high-speed filming, the structure of the flow behind the
turbine runner was analyzed, and the influence of this structure on the
intensity and frequency of pressure pulsations in the flow duct was
demonstrated.
DOI: 10.1134/S086986431801002X
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I.I. Mazhul1,2Â and Yu.P. Gounko1
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Â Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
E-mail: mazhul@itam.nsc.ru, gounko@itam.nsc.ru
Keywords: axisymmetric supersonic flow, frontal inlet of internal compression, expanding diffus-er, pseudo-shock, duct throttling
Abstract >>
The results of the numerical modeling of a flow with a pseudo-shock in an axisymmetric duct are presented. The duct included a frontal inlet with the initial funnel-shaped compression part and the cylindrical throat part as well as the subsequent expanding diffuser. To create a flow with a pseudo-shock, the duct was throttled with the use of the outlet converging insert. Numerical computations of the axisymmetric flow have been conducted on the basis of the solution of the Reynolds-averaged NavierStokes equations and with the use of the k-ω SST turbulence model. As a result of computations, such parameters of the flow were determined as the location of the beginning of the pseudo-shock, the length of its supersonic part, the velocity profiles in different cross sections of the pseudo-shock, the pressure distribution on the duct wall, the total pressure recovery factor, and others. The behavior of these parameters at the freestream Mach number Ì = 6 was analyzed versus the diffuser opening angle and different degree of the inlet duct throttling.
DOI: 10.1134/S0869864318010031
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B.F.
Boyarshinov
Kutateladze Institute of Thermophysics SB RAS,
Novosibirsk, Russia
E-mail: boyar@itp.nsc.ru
Keywords: flame blow-off, mixed convection, combustion “on the ceiling”, PIV method, Rayleigh-Taylor instability, mushroom-like structures
Abstract >>
Experimental data on the
flow structure and mass transfer near the boundaries of the region existence of
the laminar and turbulent boundary layers with combustion are considered.
These data include the results of investigation on reacting flow stability at
mixed convection, mass transfer during ethanol evaporation “on the floor” and
“on the ceiling”, when the flame surface curves to form the large-scale
cellular structures. It is shown with the help of the PIV equipment that
when Rayleigh–Taylor instability manifests, the mushroom-like structures are
formed, where the motion from the flame front to the wall and back alternates.
The cellular flame exists in a narrow range of velocities from 0.55 to 0.65
m/s, and mass transfer is three times higher than its level in the standard
laminar boundary layer.
DOI: 10.1134/S0869864318010043
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K.Yu. Arefyev1,2,3, A.N. Prokhorov1,2, and A.S. Saveliev1,4
1Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
2Baranov Central Institute of Aviation Motors, Moscow, Russia
3Bauman Moscow State Technical University, Moscow, Russia
4Joint Institute for High Temperatures RAS, Moscow, Russia
E-mail: arefyev@ciam.ru, prokhorov@ciam.ru, fisteh@mail.ru
Keywords: high-speed flow, vortex wake, liquid injection, two-phase flow, droplet fractionation
Abstract >>
The study is devoted to the establishment of regularities in the process
of liquid-droplet breakup in the vortex wake behind pylon at high subsonic
airspeeds. The article describes the laboratory setup, the diagnostic tools, and the experimental procedure. Structure
of the unsteady gas flow behind pylon was examined, and the main
characteristics of the generated vortex wake were evaluated.
Experimental data concerning the variation of droplet diameters in the
gas-dynamic fractionation process versus the flow conditions and liquid
injection regimes were obtained. Typical distributions of droplet diameters and
velocities in the vortex wake behind pylon are reported. A comparison of
experimental data on the rate of the gas-dynamic fractionation process with
calculations made using previously developed evaluation procedures was
performed. The results of the study may prove useful when choosing the
configuration of systems for implementation of liquid injection into a
high-speed flow and, also, for validation of mathematical models intended for
calculation of parameters of two-phase flows.
DOI: 10.1134/S0869864318010055
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A.S. Surtaev and V.S. Serdyukov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia
E-mail: surtaev@itp.nsc.ru
Keywords: boiling, microlayer, high-speed visualization, IR thermography, phase transitions
Abstract >>
The paper presents the results of an experimental study of dynamics of vapor bubble growth and departure at pool boiling, obtained with the use of high-speed video recording and IR thermography. The study was carried out at saturated water boiling under the atmospheric pressure in the range of heat fluxes of 30-150 kW/m2. To visualize the process and determine the
growth rates of the outer bubble diameter, microlayer region and dry spot area,
transparent thin film heater with the thickness of 1 μm deposited on sapphire substrate was used in the experiments, and video
recording was performed from the bottom side of the heating surface. To study
integral heat transfer as well as local non-stationary thermal characteristics,
high-speed infrared thermography with a frequency of up to 1000 FPS was used.
High-speed video recording showed that after formation of vapor bubble and
microlayer region, dry spot appears in a short time (up to 1 ms) under the
vapor bubble. Various stages of contact line boundary propagation were observed.
It was shown that at the initial stage before the development of small-scale
perturbations, the dry spot propagation rate is constant. It was also showed
that the bubble departure stage begins after complete evaporation of liquid
in the microlayer region.
DOI: 10.1134/S0869864318010067
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I.K. Gimaltdinov1Â and S.R. Kildibaeva2
1Ufa State Petroleum Technological University, Ufa,
Russia
2Sterlitamak Branch of the Bashkir State University, Sterlitamak, Russia
E-mail: iljas_g@mail.ru
Keywords: multiphase submerged jet, hydrate formation, leakage of hydrocarbons on the reservoir bed, petroleum ac-cumulation
Abstract >>
Submerged jets
propagating under stable hydrate conditions and flow environment are
considered. An integral Lagrangian control volume method is developed for
calculating the jet parameters: the trajectory, radius, temperature, density,
and volumetric content of jet components. The impact of two extreme schemes of
hydrate formation on the jet parameters is identified. The impact of the
initial value of the gas flow rate on the jet temperature is investigated.
DOI: 10.1134/S0869864318010079
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V.Sh. Shagapov1, 2 and A.S. Chiglintseva1,2,3
1Kazan Federal Research Center, Institute of Mechanics and Mechanical Engineering, Kazan, Russia
2Mavlyutov Institute of Mechanics, Ufa Scientific Center of RAS, Ufa, Russia
3Bashkir State University, Birsk Branch, Birsk, Russia
E-mail: changelina@rambler.ru
Keywords: gas injection, filtration, snowy aggregate, ice melting temperature, self-similar solu-tion, hydrate formation, volumetric zone, Leibenson linearization
Abstract >>
The paper considers the process of injection of hydrate-forming gas (methane) into a snowy agglomerate (initially saturated with methane). The self-similar problem statement demonstrates that if the warm gas (Te > 0 °C) is injected under a high pressure (pe > p*, where the critical values are found from the initial temperature T0, pressure p0, volumetric snow saturation S, and permeability of snow) into the filtration zone with phase transition,
this produces four characteristic zones: the nearest zone with all snow
transformed into hydrate, therefore, the aggregate filled only with gas and
hydrate, the two intermediate zones where gas, snow or water and hydrate are in
phase equilibrium state, and the distant zone filled only with gas and
snow. The obtained analytical and numerical solutions give an analysis
of the influence of key input parameters like initial state of the aggregate,
gas injection rate, and its temperature, on the structure and the length
of four filtration zones.
DOI: 10.1134/S0869864318010080
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I.L. Khabibullin, G.A. Nigametyanova, and F.F.
Nazmutdinov
Bashkir State University, Ufa, Russia
E-mail: habibi.bsu@mail.ru, gyzelua@mail.ru
Keywords: permafrost zone, permafrost, land cover, thermo-insulating layer, heat transfer, tem-perature distribution, soil freezing and thawing
Abstract >>
A
mathematical model for calculating the distribution of temperature and the
dynamics of the phase transformations of water in multilayer systems on
permafrost-zone surface is proposed. The model allows one to perform
calculations in the annual cycle, taking into account the distribution of
temperature on the surface in warm and cold seasons. A system involving four
layers, a snow or land cover, a top layer of soil, a layer of
thermal-insulation material, and a mineral soil, is analyzed. The
calculations by the model allow one to choose the optimal thickness and composition
of the layers which would ensure the stability of structures built on the
permafrost-zone surface.
DOI: 10.1134/S0869864318010092
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E.V. Bespala1, I.Yu. Novoselov2, A.O. Pavlyuk1, and S.G. Kotlyarevskiy1
1Pilot and Demonstration Center for Decommissioning of Uranium-Graphite Nuclear Reactors, Seversk, Russia
2Tomsk Polytechnic University, Tomsk, Russia
E-mail: bespala_evgeny@mail.ru
Keywords: irradiated graphite, plasma, processing, decontamination
Abstract >>
The paper describes a problem of accumulation of irradiated graphite due to operation of uranium-graphite nuclear reactors. The main noncarbon contaminants that contribute to the overall activity of graphite elements are iso-topes 137Cs, 60Co, 90Sr, 36Cl, and 3H. A method was developed for processing of irradiated graphite ensuring the volumetric decontamination of samples. The calculation results are presented for equilibrium composition of plasma-chemical reactions in systems “irradiated graphite-argon” and “irradiated graphite-helium” for a wide range of temperatures. The paper describes a developed mathematical model for the process of purification of a porous graphite surface treated by equilibrium low-temperature plasma. The simulation results are presented for the rate of sublimation of radioactive contaminants as a function of plasma temperature and plasma flow velocity when different plasma-forming gases are used. The extraction coefficient for the contaminant 137Cs from the outer side of
graphite pores was calculated. The calculations demonstrated the advantages of
using a lighter plasma forming gas, i.e., helium.
DOI: 10.1134/S0869864318010109
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M.S.M. Barforoush and S. Saedodin
University of Semnan, Semnan, Iran
E-mail: ms.motaghedi@yahoo.com
Keywords: SRC annular fins, performance analysis, convective-radiative heat loss, analytical so-lution
Abstract >>
This article investigates the
thermal performance of convective-radiative annular fins with a step reduction
in local cross section (SRC). The thermal conductivity of the fin’s
material is assumed to be a linear function of temperature, and heat transfer
coefficient is assumed to be a power-law function of surface temperature. Moreover, non-zero convection and radiation sink temperatures are included in the
mathematical model of the energy equation. The well-known
differential transformation method (DTM) is used to derive the analytical
solution. An exact analytical solution for a special case is derived to prove
the validity of the obtained results from the DTM. The model provided here is a more realistic
representation of SRC annular fins in actual engineering practices. Effects of many parameters such as conduction-convection parameters,
conduction-radiation parameter and sink temperature, and also some parameters which deal with step fins such as
thickness parameter and dimensionless
parameter describing the position of
junction in the fin on the temperature
distribution of both thin and thick sections of the fin are investigated. It is
believed that the obtained results will facilitate the design and performance
evaluation of SRC annular fins.
DOI: 10.1134/S0869864318010110
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S.P. Rusin
Joint Institute for High Temperatures RAS,
Moscow, Russia
E-mail: sprusin@mail.ru
Keywords: true temperature, spectrum of thermal radiation, relative emissivity
Abstract >>
A method for determining
the thermodynamic (true) temperature of opaque materials by the registered
spectrum of thermal radiation under the conditions when we do not know
emissivity of a free-radiating body is presented. A special function,
which is a product of relative emissivity of tungsten by the radiation
wavelength, was used as the input data. The accuracy of results is analyzed. It
is shown that when using relative emissivity, the proposed algorithm can be
used both within the range of applicability of the Wien approximation and the
Planck formula.
DOI: 10.1134/S0869864318010122
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S.D. Sleptsov and N.A. Rubtsov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
E-mail: sleptsov@itp.nsc.ru
Keywords: spherical particle, leucosapphire, absorptance, transmittance, reflectance, absorption coefficient
Abstract >>
The optical properties
(absorptance, transmittance, and reflectance) of a spherical particle are
analyzed when its diameter is much larger than the wavelength of monochromatic
radiation. To do this, previously obtained solution of the integral equation of
monochromatic radiation is used. The agreement of calculations with
experimental data obtained for leucosapphire is shown.
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V.P. Zamuraev and A.P. Kalinina
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia
E-mail: Zamuraev@itam.nsc.ru, Kalinina@itam.nsc.ru
Keywords: supersonic flow, duct, near-wall energy sources, jet, Euler and Navier-Stokes equa-tions
Abstract >>
The
control simultaneous action of a jet and near-wall energy sources on the
shockwave structure of a superso-nic flow in the axisymmetric and planar ducts
is studied for the purpose of creating a transonic region. The regimes with an
extended transonic region are obtained.
DOI: 10.1134/S0869864318010146
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Editorial Board
Siberian Branch of the RAS, Novosibirsk, Russia
Abstract >>
February 11, 2018 is the
date of the 60th anniversary of a brilliant scientist in the field of
multiphase media physics and a specialist in cold gas spraying, Professor
Vladimir F. Kosarev.
DOI: 10.1134/S0869864318010158
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