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2017 year, number 4
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H. Abdollahi1, S. Shahraki1, and M. Motahari-Nezhad2
1University of Zabol, Zabol, Iran
2Iran University of Science and Technology, Tehran, Iran
E-mail: saeid.shahraki@uoz.ac.ir
Keywords: contact heat transfer, thermal contact conductance, experimental setup, numerical solution
Pages: 499–512
Abstract >>
In this paper, a
complete literature review for thermal contact between fixed and periodic
contacting surfaces and also thermal contact between exhaust valve and its seat
in internal combustion engines is presented. Furthermore, the effects of some parameters
such as contact pressure, contact frequency, the contacting surfaces topography
and roughness, curvature radius of surfaces, loading–unloading cycles, gas gap
conductance and properties, interface interstitial material properties,
surfaces coatings and surfaces temperature on thermal contact conductance are
investigated according to the papers presented in this field. The reviewed
papers and studies included theoretical/analytical/experimental and numerical
studies on thermal contact conductance. In studying the thermal contact between
exhaust valve and its seat, most of the experimental studies include two axial
rods as the exhaust valve, and seat and the one ends of both rods are
considered at constant and different temperatures. In the experimental methods,
the temperatures of multi-points on rods are measured in different conditions,
and thermal contact conductance is estimated using them.
DOI: 10.1134/S0869864317040011
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A.B. Kaplun and A.B.
Meshalkin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
E-mail: kaplun@itp.nsc.ru
Keywords: fundamental equation, compressibility factor, temperature, pressure, density, enthalpy, heat capacity, sound velocity
Pages: 513–522
Abstract >>
A new fundamental
low-parametric equation of state in the form of reduced Helmholtz function for
describing thermodynamic properties of normal substances was obtained using the
methods and approaches developed earlier by the authors. It allows us to
describe the thermal properties of gas, liquid, and fluid in the range from the
density in ideal-gas state to the density at a triple point (except the
critical region) with sufficiently high accuracy close to the ac-curacy of
experiment. The caloric properties and sound velocity of argon, nitrogen, and
carbon dioxide are calculated without involving any caloric data, except the
ideal gas enthalpy. The obtained values of isochoric heat capacity, sound
velocity, and other thermodynamic properties are in good agreement with
experimental (reliable tabular) data.
DOI: 10.1134/S0869864317040023
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Yu.B. Zudin
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National Research Centre “Kurchatov Institute”, Moscow, Russia
E-mail: yzudin@gmail.com">yzudin@gmail.com";s:4:"TYPE";s:4:"html";}
Keywords: semi-empirical model, intense evaporation, linear kinetic theory, extrapolation drops for parameters, vapor parameters, gas-dynamic region
Pages: 523–536
Abstract >>
A semi-empirical model based on
the linear kinetic theory was developed for intense evaporation. The
extrapolated drops for pressure and temperature at the condensed phase surface
were calculated through summing of linear and squared terms. The analytical
dependencies were obtained for gas parameters in gas-dynamic zone as functions
of Mach number, condensation coefficient, and the number of degrees of freedom
for molecules of ideal gas. The calculations from semi-empirical model are in
agreement with results from known analytical and numerical studies.
DOI: 10.1134/S0869864317040035
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B.P. Avksentyuk1 and V.V. Ovchinnikov2
1Vinnytsa Institute of Trade and Economics of Kyiv National University of Trade and Economics, Vinnitsa, Ukraine
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
E-mail: avks@itp.nsc.ru
Keywords: boiling, subcooling, evaporation front, heat transfer crisis
Pages: 537–544
Abstract >>
Results of experimental
studies on dynamics of explosive boiling and third heat transfer crisis under
the conditions of liquid subcooling are presented for the vertical
arrangement of the heat-transfer surface. Acetone was used in experiments at
the pressure in the working volume from 20 to 46 kPa and subcooling from 0 to
20 K. The studied processes were recorded. Data on the velocity of
evaporation front propagation at liquid subcooling were obtained. These data
are compared with the results of calculations according to the models available
in the literature. The effect of liquid subcooling on the regions of regime
parameters corresponding to explosive boiling and third heat transfer crisis is
studied.
DOI: 10.1134/S0869864317040047
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V.L. Okulov1, 2, I.V. Naumov1, M.A. Tsoy1, and R.F. Mikkelsen2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Denmark Technical University, Lyngby, Denmark
E-mail: vaok@dtu.dk
Keywords: wind farm, rotor wake, interaction between turbines and wakes, power loss of wind turbines
Pages: 545–551
Abstract >>
The efficiency of a pair
of wind turbines is experimentally investigated for the case when the model of
the second rotor is coaxially located in the wake of the first one. This
configuration implies the maximum level of losses in wind farms, as in the
rotor wakes, the deceleration of the freestream is maximum. As a result of
strain gauge measurements, the dependences of dimensionless power
characteristics of both rotors on the distances between them were determined
for different modes at different tip speed ratios. The obtained results are of interest
for further development of aerodynamics of wind turbines, for optimizing the
work of existing wind farms and reducing their power losses due to interactions
with wakes of other wind turbines during design and calculation.
DOI: 10.1134/S0869864317040059
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D.V. Brezgin1, K.E. Aronson1, F. Mazzelli2, and A. Milazzo2
1Ural Federal University named after the First President of Russia B.N. Eltsin: Ural Power Engineering Institute, Ekaterinburg, Russia
2University of Florence, Florence, Italy
E-mail: k.e.aronson@urfu.ru
Keywords: supersonic ejector, entrainment ratio, CFD, wall log-law, sand-grain roughness
Pages: 553–561
Abstract >>
The
paper presents the numerical simulation results of the surface roughness influence
on gas-dynamic processes inside flow parts of
a supersonic ejector. These simulations are performed using two commercial CFD
solvers (Star-CCM+ and Fluent). The results are compared to each other and
verified by a full-scale experiment in terms of global flow parameters (the
entrainment ratio: the ratio between secondary to primary mass flow rate - ER
hereafter) and local flow parameters distribution (the static pressure distribution
along the mixing chamber and diffuser walls). A detailed comparative study of
the employed methods and approaches in both CFD packages is carried out in
order to estimate the roughness effect on the logarithmic law velocity
distribution inside the boundary layer. Influence of the surface roughness is
compared with the influence of the backpressure (static pressure at the ejector
outlet). It has been found out that
increasing either the ejector backpressure or the surface roughness height, the
shock position displaces upstream. Moreover, the numerical simulation results
of an ejector with rough walls in the both CFD solvers are well quantitatively
agreed with each other in terms of the mean ER and well qualitatively agree in
terms of the local flow parameters distribution. It is found out that in the
case of exceeding the “critical roughness height” for the given boundary
conditions and ejector’s geometry, the ejector switches to the “off-design”
mode and its performance decreases considerably.
DOI: 10.1134/S0869864317040060
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V.V. Shumskii and
M.I. Yaroslavtsev
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
E-mail: shumsky@itam.nsc.ru, yaroslav@itam.nsc.ru
Keywords: hot-shot wind tunnel, settling chamber, test gas, stabilization of parameters, pressure multiplier, controlled diaphragm, driver air
Pages: 563–568
Abstract >>
In the present paper, we
analyze emergency situations typical of short-duration wind tunnels with
electric-arc or combined test-gas heating in the presence of stabilization and
diaphragm-rupturing systems, which occur in the case of no discharge initiation
in the settling chamber, with the capacitor battery having remained charged during
the start of wind-tunnel systems. For avoiding such emergency situations, some
additional changes based on using feedback elements are introduced into the
wind-tunnel design: the piston of the fast-response valve is made hollow for
increasing the volume of the shutoff cavity and for making the release of
pressure from this cavity unnecessary; the high-pressure channel, which
connects the piston and the piston rod with the settling-chamber cavity, is
filled with a liquid and is closed from the side of the settling chamber with a
piston; the device for controlled diaphragm breakdown is provided with an
external electric circuit intended to control the diaphragm-rupturing process.
Those modifications allow subsequent functioning of the wind-tunnel systems
only in the presence of heat-supply-induced pressure growth in the settling
chamber of the wind tunnel.
DOI: 10.1134/S0869864317040072
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V.M. Molochnikov1,2, N.I. Mikheev1,2, A.N. Mikheev1, and A.A. Paereliy1
1Kazan Scientific Center RAS, Kazan, Russia
2Kazan National Research Technical University named after A.N.Tupolev, Kazan, Russia
E-mail: vmolochnikov@mail.ru
Keywords: heat transfer, cylinder in cross-flow, forced flow pulsations, dimensionless number, empirical correlation, correction factor
Pages: 569–575
Abstract >>
The paper presents
results on heat transfer from a cylinder in pulsating flow. The results are
local heat transfer distributions that match four different flow modes identified
previously by the authors. A new kind of dimensionless number was introduced
for pulsating flows: this is a ratio of flow acceleration during unsteady
movement to the centrifugal acceleration due to streamlines bending over the
cylinder. The experimental data were generalized as a dependency of the average
heat transfer on the new dimensionless criterion. The generalization offered a
correction factor to a traditional relation for heat transfer between a
cylinder and air flow past the cylinder; this correction takes into account the
effect of parameters of forced flow pulsations on the average heat transfer.
DOI: 10.1134/S0869864317040084
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V.I. Terekhov1,2, A.L. Ekaid3, and K.F. Yassin2,4
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1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
3University of Technology, Baghdad, Iraq
4Northern Technical University, Kirkuk, Iraq
Е-mail: terekhov@itp.nsc.ru">terekhov@itp.nsc.ru";s:4:"TYPE";s:4:"html";}
Keywords: laminar free convection, heat transfer, flow separation
Pages: 577–581
Abstract >>
The results of numerical computations of a free laminar convection and heat transfer between two parallel isothermal plates in the presence of a single rib on the channel surface are presented. The investigations have been conducted for a channel with the aspect ratio AR = L/w = 10, where L is the channel height, and w is the distance between the plates. An infinitely thin adiabatic rib was located on one of the channel walls in the middle of its height. The relative rib height l/w was varied in the range 0¸0.8. The wall temperature was higher than the ambient temperature, and the Rayleigh number was varied in the range Ra = 102¸105. The main attention has been
paid to the study of the influence of the rib height and the Rayleigh number on
local and integral heat transfer and the Reynolds number in the channel (the
convective thrust). A fundamental difference in the heat transfer over the
channel height has been shown on the ribbed wall and on a smooth surface. The
computational results have been compared with the case of a symmetric distribution
of the ribs on the both walls with the integral height equal to a single rib.
DOI: 10.1134/S0869864317040096
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V.S. Teslenko, A.P. Drozhzhin, and
R.N. Medvedev
Lavrentiev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
E-mail: teslenko@hydro.nsc.ru
Keywords: pulse combustion of gas in water, force pulses, thrust, specific thrust, hydrojet propulsion
Pages: 583–591
Abstract >>
The paper presents the results of experimental study for hydrodynamic processes occurring during combustion of a stoichiometric mixture propane-oxygen in combustion chambers with different configurations and submerged into water. The pulses of force acting upon a thrust wall were measured for different geometries: cylindrical, conic, hemi-spherical, including the case of gas combustion near a flat thrust wall. After a single charge of stoichiometric mixture propane-oxygen is burnt near the thrust wall, the process of cyclic generation of force pulses develops. The first pulse is generated due to pressure growth during gas combustion, and the following pulses are the result of hydrodynamic pulsations of the gaseous cavity. Experiments demonstrated that efficient generation of thrust occurs if all bubble pulsations are used during combustion of a single gas combustion. In the series of experiments, the specific impulse on the thrust wall was in the range 104-105 s (105-106 m/s) with account for positive and negative components of impulse.
DOI: 10.1134/S0869864317040102
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D.O. Glushkov*,
G.V. Kuznetsov, and P.A. Strizhak
National Research Tomsk Polytechnic University, Tomsk, Russia
E-mail: dmitriyog@tpu.ru*
Keywords: grinded coal, hot particle, heat transfer, volatiles, diffusion, gas-phase ignition
Pages: 593–604
Abstract >>
Characteristics of
gas-phase ignition of grinded brown coal (brand 2B, Shive-Ovoos deposit in
Mongolia) layer by single and several metal particles heated to a high
temperature (above 1000 K) have been investigated numerically. The developed
mathematical model of the process takes into account the heating and thermal decomposition
of coal at the expense of the heat supplied from local heat sources, release of
volatiles, formation and heating of gas mixture and its ignition. The
conditions of the joint effect of several hot particles on the main
characteristic of the process – ignition delay
time are determined. The relation of the ignition zone position in the vicinity
of local heat sources and the intensity of combustible gas mixture warming has
been elucidated. It has been found that when the distance between neighboring
particles exceeds 1.5 hot particle size, an analysis of characteristics and
regularities of coal ignition by several local heat sources can be carried out within the framework of the model of
“single metal particle / grinded coal / air”. Besides, it has been shown with
the use of this model that the increase in the hot particle height leads, along
with the ignition delay time reduction, to a reduction of the source initial
temperatures required for solid fuel ignition. At an imperfect thermal
contact at the interface hot particle / grinded coal due to the natural porosity
of the solid fuel structure, the intensity of ignition reduces due to a less
significant effect of radiation in the area of pores on the heat transfer
conditions compared to heat transfer by conduction in the near-surface coal
layer without regard to its heterogeneous structure.
DOI: 10.1134/S0869864317040114
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V.E. Messerle1,2 and A.B. Ustimenko3,4*
1Institute of Combustion Problems, Almaty, Kazakhstan
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3NTO Plasmotekhnika Ltd., Almaty, Kazakhstan
4Research Institute of Experimental and Theoretical Physics, Almaty, Kazakhstan
E-mail: ust@physics.kz*
Keywords: organic waste, plasma processing, fuel gas, kinetic modeling, calculation
Pages: 605–614
Abstract >>
Kinetic calculations
of the plasma processing/utilization process of organic waste in air and steam
ambient were carried out. It is shown that, during the time of waste residence
in the plasma reactor, 0.7 and 1.2 s, at the exit from the reactor there
forms a high-calorific fuel gas with a combustion heat of 3540 and
5070 kcal/kg, respectively. In this process, 1 kg of waste yields 1.16 kg of fuel gas at air
gasification of waste and 0.87
kg of pure synthesis gas at steam gasification. The energy efficiency of the waste gasification
process, defined by the ratio between the calorific value of the resultant fuel
gas and the initial calorific value of the waste amounts to 91 % in
air plasma and 98 % in steam plasma. A comparison between the results of
kinetic and thermodynamic calculations has revealed their good agreement.
DOI: 10.1134/S0869864317040126
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V.A. Faleev1, E.B. Butakov1, and S.I. Radko2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
E-mail: v.faleev2010@yandex.ru
Keywords: organic waste, gasification, heat content, gas composition, power inputs
Pages: 615–620
Abstract >>
Thermodynamic analysis of
plasma gasification of various renewable carbon-bearing materials was carried
out using various oxygen-containing oxidants (oxygen, air, water). The
possibility of obtaining calorific synthesis gas suitable for the needs of heat
power engineering was confirmed.
DOI: 10.1134/S0869864317040138
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A.Kh. Abduev1*, A.K. Akhmedov1, A.Sh. Asvarov1,2, K.Sh. Rabadanov2, R.M. Emirov3, S.P. Vashchenko4, I.P. Gulyaev4, V.I. Kuzmin4**, and D.V. Sergachev4
1Amirkhanov Institute of Physics, Dagestan Scientific Center RAS,
Makhachkala, Russia
2Dagestan Scientific Center RAS, Analytical Center for Collective Use,
Makhachkala, Russia
3Dagestan State University, Makhachkala, Russia
4Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
E-mail: a_abduev@mail.ru*; vikuzmin57@mail.ru**
Keywords: titanium oxide, rutile, plasma spraying, microstructure
Pages: 621–627
Abstract >>
Structure of ceramics obtained by the plasma spray deposition of spherical TiO2
powders has been investigated. An electron microscopy study of the surfaces and cross sections of particles in the initial powder and of the deposited ceramic coatings was performed. X-ray diffraction and Raman scattering data proved that the coatings were mainly structured as rutile. In addition, Raman and X-ray diffraction data have revealed an amorphous phase, an anatase phase, and non-stoichiometric phases Ti8O15, Ti10O19, Ti7O13, etc.
being present in the coatings. The observed suppression of (011) and (111) XRD peaks and an
increased intensity of (110) peak are indicative of a predominant orientation
of grains in the synthesized ceramics. Mechanisms of formation of the complex
coating structure are discussed.
DOI: 10.1134/S086986431704014X
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S.G.
Mironov, T.V. Poplavskaya, and S.V. Kirilovskiy
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia
E-mail: mironov@itam.nsc.ru
Keywords: supersonic flow around a body, gas-permeable cellular-porous materials, impact of temperature, numerical simulation
Pages: 629–632
Abstract >>
In the present paper, we report on experimental and simulated data on the impact of cellular-porous-material heating on the wave drag of a cylinder with a frontal gas-permeable porous insert streamlined by a supersonic flow (М∞ = 4.85, Re1∞ = 3.3×106
m-1). Weighing data obtained in the supersonic wind tunnel are
compared with data simulated using a discrete model of the cellular-porous
material. An increase of the wave drag with a growth of porous-insert
temperature and its decrease occurring upon decreasing the temperature are
demonstrated.
DOI: 10.1134/S0869864317040151
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P.A. Shchinnikov and N.V. Marasanov*
Novosibirsk State Technical University, Novosibirsk, Russia
E-mail: nikmarasanov@gmail.com*
Keywords: Rankine cycle, Otto cycle, efficiency, mini-TPP, energy flow
Pages: 633–636
Abstract >>
The
technology of electricity production by a mini-thermal power plant, operating
on combined cycles of Otto and Rankine, is considered. The main aspects of the
investigation methodology are outlined. It is shown that the design and layout
parameters of all the major energy elements of the developed technology allow
implementing it in a block and modular version; and the efficiency of
electricity supply for the proposed technology will be at least 50 %.
DOI: 10.1134/S0869864317040163
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Editorial Board
Siberian Branch of the RAS, Novosibirsk, Russia
Pages: 637– 638
Abstract >>
4 August, 2007 is the
70th Anniversary of the well known scientist, Doctor of the Physical and
Mathematical Sciences, Professor Amir A. Gubaidullin.
DOI: 10.1134/S0869864317040175
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