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Thermophysics and Aeromechanics

2018 year, number 1

1.
The role of laboratory testing in the development of rotor aerodynamics (review)

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
																								



2.
Experimental study of pressure pulsations in the flow duct of a medium-size model hydroelectric generator with Francis turbine

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
																								



3.
Numerical simulation of the flow with a pseudo-shock in an axisymmetric expanding duct with a frontal inlet

I.I. Mazhul1,2 and Yu.P. Gounko1

1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS,  Novosibirsk, Russia

2Novosibirsk State Technical University, Novosibirsk, Russia

E-mail: mazhul@itam.nsc.rugounko@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 NavierStokes 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 = 6 was analyzed versus the diffuser opening angle and different degree of the inlet duct throttling.

DOI: 10.1134/S0869864318010031
																								



4.
Experimental investigation of the limits of ethanol combustion in the boundary layer behind an obstacle

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 RayleighTaylor 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
																								



5.
Study of the breakup of liquid droplets in the vortex wake behind pylon at high airspeeds

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
																								



6.
Investigation of contact line dynamics under a vapor bubble at boiling on the transparent heater

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
																								



7.
Model of a submerged jet accounting for two limiting schemes of hydrate formation

I.K. Gimaltdinov1 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
																								



8.
On injection of hydrate-forming gas into a gas-saturated snowy agglomerate while transition through the ice melting point

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
																								



9.
Heat transfer and phase transitions of water in multi-layer cryolithozone-surface systems

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
																								



10.
Study of evaporating the irradiated graphite in equilibrium low-temperature plasma

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
																								



11.
Annular convective-radiative fins with a step change in thickness, and temperature-dependent thermal conductivity and heat transfer coefficient

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 fins 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
																								



12.
Using spectral distribution of radiance temperature and relative emissivity for determination of the true temperature of opaque materials

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
																								



13.
Analytical assessment of optical coefficients of a semitransparent spherical particle

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.
																								



14.
Transonic region formation at the thermal and gas-dynamic action on a supersonic duct flow

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
																								



15.
60th Anniversary of Vladimir Kosarev

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