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Thermophysics and Aeromechanics

2018 year, number 6

1.
Experimental study of the influence of small angles of attack and cone nose bluntness on the stabilization of hypersonic boundary layer with passive porous coating

S.O. Morozov1, S.V. Lukashevich1, V.G. Soudakov2, A.N. Shiplyuk1
1Khristianovich Institute of Theoretical and Applied Mechanics SB RASNovosibirsk, Russia
2Zhukovsky Central Aerohydrodynamic InstituteZhukovsky, Russia
E-mail: morozov@itam.nsc.ru
Keywords: hypersonic boundary layer, passive porous coating, boundary-layer stability, laminar-turbulent transition, second-mode disturbances.
Pages: 793800

Abstract >>

The present work was devoted to an experimental study of small angles of attack and cone nose bluntness on the efficiency of stabilization of high-frequency disturbances in hypersonic boundary layer with a passive porous coating. The experiments were carried out on a cone with an apex half-angle 7 and nose bluntness radii R = 0.03, 0.5 and 1 mm installed under angles of attack a = 01 at the freestream Mach number M¥ = 5.8. High-frequency pressure fluctuations on the sides of the cone with the solid and porous surfaces were measured. It is shown that at all angles of attack and cone bluntness, the passive porous coating permits an efficient suppression of disturbances in hypersonic boundary layer both on the windward and leeward sides of the cone.

																								



2.
Investigation of the impulse action of a membrane on the straight wing boundary layer

M.M. Katasonov1, A.M. Pavlenko1, V.V. Kozlov1,2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
E-mail: mikhail@itam.nsc.ru
Keywords: boundary layer, separation, laminar-turbulent transition, longitudinal localized struc-ture, wave packet
Pages: 801807

Abstract >>

The hot-wire anemometry technique is used to study the development of controlled disturbances in a straight wing boundary layer. Three-dimensional surface oscillations with large amplitude generate two types of disturbances: the localized longitudinal structures and wave packets. In downstream direction, the intensity of localized longitudinal structures decreases. The wave packets manifest themselves near the fronts of longitudinal localized structure in the flow region with adverse pressure gradient. In the separation flow area, an intensive growth of the wave packets amplitude is observed. The spatial development of the wave packets coincides with the development of three-dimensional Tollmien-Schlichting wave under similar conditions.

																								



3.
The motion of vortices in a two-dimensional bounded region

P.I. Geshev1,2, A.I. Chernykh1,3
1Novosibirsk State University, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
3Institute of Automation and Electrometry SB RAS, Novosibirsk, Russia
E-mail: geshev@itp.nsc.ru
Keywords: ideal fluid, point vortex, Hamiltonian, exact integration, stochastic trajectories
Pages: 809822

Abstract >>

The Hamiltonian equations of the motion of a system of N ideal point vortices in a simply connected two-dimensional region have been obtained by the methods of the theory of functions of a complex variable. It is shown that the motion of two vortices in a circle is integrated exactly; the periods of this motion have been determined. The motion of two vortices in a region bounded by a lemniscate has been investigated by the method of secant planes in the phase space. The stochastic trajectories have been revealed here, which have continuous power spectra. The supposed reason for stochasticity is the walk of the phase point over a homoclinic structure.

																								



4.
Experimental determination of the helium permeability coefficient of hollow mi-crospherical membranes

V.N. Zinovyev, I.V. Kazanin, V.A. Lebiga, A.Yu. Pak, N.G. Tsibulsky, A.S. Veresh-chagin, V.M. Fomin
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
E-mail: zinoviev@itam.nsc.ru, kazaniniv@gmail.com
Keywords: helium, microspheres, helium permeability, gas separation, natural gas, membrane-sorption method
Pages: 823831

Abstract >>

The paper is devoted to the study of the permeability of hollow microspherical membranes to helium with a narrow fraction of MS-V-1L microspheres taken as an example. In the course of the study, a special experimental facility for obtaining the sorption curves of various gases at given pressures and temperatures was created. A procedure for carrying out experiments and processing experimental data with the aim of evaluating the coefficient of helium permeability for the investigated type of hollow membranes was approbated. For the selected narrow fraction of MS-V-1L microspheres with diameters in the range from 35 to 50 mm, the helium permeability coefficient of the particle-wall material in the temperature range from 20 to 110 C and the activation energy of the helium sorption process by the microspheres were determined.

																								



5.
Effect of droplet evaporation on the flow structure and heat and mass transfer in a confined swirling gas-droplet flow downstream of a tube sudden expansion

M.A. Pakhomov and V.I. Terekhov
Kutateladze Institute of Thermophysics SB RAS,
Novosibirsk, Russia
E-mails: pakhomov@ngs.ru, terekhov@itp.nsc.ru
Keywords: gas-droplet flow, separation, swirl, evaporation, numerical simulation, turbulence, model of Reynolds stress transport
Pages: 833843

Abstract >>

The effect of flow swirl parameter and thermophysical properties of the droplet of water, ethanol, and acetone on the structure of turbulent flow and heat transfer in a gas-droplet flow was studied numerically. To describe the dynamics and heat and mass transfer of the two-phase flow, the Eulerian approach was used. The growth of the volume fraction of small particles on the tube axis is typical of a swirling flow because of their accumulation in the zone of reverse flows due to the turbophoresis force. It is shown that the addition of droplets leads to a significant increase in heat transfer (more than 2.5 times) at mass concentration of droplets ML1 = 0.1 in comparison with a single-phase swirling flow. Intensification of heat transfer with the use of ethanol droplets is higher than that for water droplets (approximately 1020 %) and acetone (up to 65 %). When using the droplets of ethanol and acetone, the region of two-phase flow existence reduces, and the degree of suppression of carrier phase turbulence decreases. This is due to a more rapid evaporation of droplets of volatile liquids.

																								



6.
Thermoviscous fluid flow modes in a plane nonisothermal layer

Y.M. Kulikov, E.E. Son
Joint Institute for High Temperatures RAS, Moscow, Russia
E-mail: kulikov-yurii@yandex.ru; son.eduard@gmail.com
Keywords: thermoviscosity, inflection point, random noise, mixing, correlation filter, correction for divergence, turbulence
Pages: 845864

Abstract >>
This paper deals with 3D flow of thermoviscous fluid in the low compressibility approximation within a cubic-shaped domain enclosed between two flat plates with different temperatures. For two other directions, the problem statement assigns periodic boundary conditions, while the steady pressure drop is sustained for the head flow direction. Such formulation allows to trace the evolution of initial disturbances imposed on the main flow depending on perturbation properties. In this case, we consider a degenerate one-dimensional divergence-free noise  that is modified by a special correlation filter. When the divergent noise is generated, the solenoid nature of random velocity field must be restored. The simulation demonstrates that random disturbance field development leads to two different scenarios: for the first low-amplitude case, the velocity profile loses initial inflection point and its flowrate increases by 1.5-1.6 times, but for the second one, the flow turbulization occurs destroying the flow core and decreasing the flowrate. In both outcomes, the transition to a steady flow mode in terms of  either stationary velocity fields or statistical averages takes place for a long interval: up to  dimensionless time units. The analysis of simulated flow is based on integral kinetic energy curves and enstrophy and also via spatial averaging of the obtained data arrays. 
																								



7.
Movement of liquid rivulet in a microchannel with a co-current gas flow

Yu.O. Kabova1, V.V. Kuznetsov2,3, O.A. Kabov1,3
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
3Novosibirsk State University, Novosibirsk, Russia
E-mail: kabov@itp.nsc.ru
Keywords: two-phase flows, rivulets, microchannels, numerical studies
Pages: 865874

Abstract >>

The joint steady-state motion of a rivulet of incompressible liquid and a gas flow in a microchannel was studied taking into account the action of gravity forces, tangential stress at the gas-liquid interface, and Van der Waals forces. The values of contact angle are calculated for various values of liquid and gas flow rates. It is shown that for a constant liquid flow rate, an increase in gas velocity leads to a decrease in the height of rivulet, and the surface of rivulet becomes flatter. A significant deforming effect of rivulet on the velocity distribution in gas is found.

																								



8.
Self-oscillatory regime of boiling of a highly subcooled liquid in a flow-passage annular duct

S.P. Aktershev1, A.A. Levin2, I.V. Mesentsev1, and N.N. Mesentseva1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Melentiev Institute of Power Engineering Systems SB RAS, Irkutsk, Russia
E-mail: sergey-aktershev@mail.ru
Keywords: boiling, subcooled liquid, evaporation, condensation, pressure pulsations, self-oscillations
Pages: 875887

Abstract >>

The results of an experimental and theoretical investigation of highly subcooled ethanol in an annular flow-passage duct under the conditions of pulsed heat generation in the wall cooled by liquid flow are presented. The formation of a vapor film on the heater wall and long-lasting pressure oscillations of high amplitude in the duct (the self-oscillatory regime) have been observed in experiments. A mathematical model of the ethanol boiling up has been developed to take into account the evaporation of the overheated liquid near the heater wall and the vapor condensation in the flow of a subcooled liquid. The proposed model describes both the decaying oscillations of the vapor layer and the development of the self-oscillatory regime, which predicts well the amplitude and frequency of nonlinear oscillations. Numerical computations have shown that the self-oscillatory regime is realized due to evaporation of a periodically renewed microlayer on the heater wall. Computational results agree well with experimental data.

																								



9.
The influence of the temperature dependence of thermal conductivity and emissiv-ity on the temperature field in a photoacoustic cell with two-layer samples

T.Kh. Salikhov, Yu.P. Khodjaev
SRI of Tajik National University, Dushanbe, Republic of Tajikistan E-mail: tsalikhov@mail.ru
Keywords: temperature field, photoacoustics, two-layer systems
Pages: 889896

Abstract >>
Based on the system of nonlinear equations of thermal conductivity for stationary temperatures of the gas layer, substrate, the first and the second layers of samples with a volumetric optical absorption coefficient, the features of the formation of a stationary temperature field in the photoacoustic cell have been investigated. Analytical expressions for the temperature field of the gas layer, two layers of the sample and the substrate, as well as a system of interrelated nonlinear algebraic equations for the steady-state temperature of the irradiated and rear surfaces of the first layer and the boundary between the second layer and the substrate have been obtained. The numerical solution of the system of nonlinear algebraic equations shows that with the increase of the absorption coefficient of the corresponding layer and the gradual transition from the condition (is the  layer thickness) to the condition, heating increases significantly, and the dependences of the characteristic temperatures on the intensity of the incident beam become nonlinear. It is shown that the sign of the thermal coefficient of the temperature dependence of emissivity significantly affects the dependences of the temperature increment of the surfaces of all layers on the intensity of the incident beam.
																								



10.
The influence of pulsed 2-laser radiation on the transport of powder during la-ser cladding of metal

D.V. Sergachev1, O.B. Kovalev1, G.N. Grachev2, A.L. Smirnov2, P.A. Pinaev2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Institute of Laser Physics SB RAS, Novosibirsk, Russia
E-mail: yosergach@gmail.com
Keywords: two-phase flow, pulsed laser radiation, evaporation, vapor recoil pressure, reactive acceleration, optical diagnostics
Pages: 897908

Abstract >>
The problem of measurement of the in-flight velocity and temperature of particles in the light field of a pulsed-periodic laser was solved using contactless detection methods. The solution of the problem is based on using a spectrometer and a complex of laser and optical means. The diagnostic technique combines two independent methods for measuring the in-flight particle velocity: a passive one, based on the registration of the natural radiation emitted by the heated particles in the gas flow, and an active one, using the effect due to laser-beam scattering. Histograms of the statistical distributions of particle velocities for two operating modes of a coaxial nozzle were presented. There is no laser radiation in the first mode. There is pulsed laser radiation in the second mode. In the experiments, various powders (Al2O3, Mo, Ni, Al) with particle size distributions typical of laser deposition technology and various working gases (air, nitrogen, argon) were used. 2-laser works in pulse-periodic mode with a mean power up to 2 kW. Pulsed power reaches several ten/hundred kilowatts. It is shown that in the field of laser radiation, powder particles acquire additional acceleration due to the evaporation and the appearance of a reactive force due to the recoil pressure of the vapors emitted from the irradiated part of the particle surface. It is shown that laser radiation can significantly affect the velocity and temperature of powder particles being transported by a gas jet. At the maximum carrier-gas velocity of up to 30 m/s, the velocities of single particles due to the laser-induced acceleration can reach the values of the order of 120 m/s.
																								



11.

Experimental study of alkaline-surfactant-polymer compositions for ASP-flooding of cores from highly viscous oil reservoirs

U.K. Zhapbasbayev, S.E. Kudaibergenov, A.E. Mankhanova, and R.M. Sadykov
Kazakh National Research Technical University after K.I. Satpaev, Almaty, Kazakhstan
E-mail: uzak.zh@mail.ru
Keywords: highly viscous oil, alkaline-surfactant-polymer (ASP) flooding, Winsor type III emul-sion, phase behavior
Pages: 909916

Abstract >>
The paper presents experiments on using alkali-surfactant-polymer compositions (for ASP flooding) in tests on cores saturated with highly viscous oil. The phase behavior was evaluated for solutions with different concentrations of alkali (NaOH) and surfactant (SDS) after mixing with highly viscous oil samples; this defined the optimal agent compositions for producing Winsor type III emulsions. Experiments on core saturated with highly viscous oil demonstrated the pumping of ASP agent in the form of aquatic solutions surfactant/alkali and polymer after regular water flooding give the gain in the oil displacement in the range from 19 to 37 %.
																								



12.

Study of solid hydrocarbon gasification in spherical bedding under high-temperature gas flow

K.Yu. Arefyev1,2,3, K.V. Fedotova1,2, L.S. Yanovsky1,4, M.A. Ilchenko1, and K.T. Niazbaev1,2
1Baranov Central Institute of Aviation Motors, Moscow, Russia
2Bauman Moscow State Technical University, Moscow, Russia
3Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russia
4Institute of Problems of Physical Chemistry, Chernogolovka, Moscow Region, Russia
E-mail: fedkv_89@mail.ru
Keywords: solid hydrocarbons, simulation, two-chamber low-temperature gas generator, LTGG, sublimation, azines
Pages: 917928

Abstract >>
The paper presents a mathematical model and calculation results for the process of gasification of solid hydrocarbons (SHC) placed in form of spherical bedding inside channels with variable cross section and washed with high-temperature gas. Parametric study was performed for analysis of generator performance (mass flow rate and gasification products) as function of different parameters: temperature and composition of gas phase, thermophysical properties of SHC, sphere diameter in the bedding, and channels configuration. The method for estimating the SHC gasification process in a flow duct of low temperature gas generator (LTGG) without loss of spheres shape (due to melting) was developed. The method offers recommendations for obtaining the required level of mass flow rate and gas temperature at the generator exit. These data can be used for analysis of experimental results on SHC sublimation at the stage of preliminary designing of the LTGG.
																								



13.

Investigating the efficiency of a steam-turbine heating plant with a back-pressure steam turbine and waste-heat recovery

A.M. Kler, E.L. Stepanova, and A.S. Maksimov
Melentiev Energy Systems Institute SB RAS, Irkutsk, Russia E-mail: step@isem.irk.ru
Keywords: steam-turbine heating plant, mathematical modeling, optimization, efficiency of heat power equipment, steam turbine with back pressure, waste-heat recovery
Pages: 929938

Abstract >>
The article considers a promising steam-turbine heating plant, which includes a steam turbine with back pressure and a steam boiler operating on natural gas, with waste heat recovery. The mathematical model of steam-turbine heating plant has been developed to perform one design calculation in the nominal mode and several verification calculations in characteristic modes with different thermal loads. Optimization calculations of the unit were carried out for two regions with different climatic conditions and different fuel prices. The optimal design parameters of the equipment, the parameters of the working fluid and coolants at all points of the technological scheme, as well as fuel costs in each characteristic mode of operation have been found by the criterion of the minimum price of electricity. The considered steam-turbine heating plant provides a higher heat utilization coefficient of the fuel than the traditional heating plant.