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Thermophysics and Aeromechanics

2016 year, number 5

Effect of the surface roughness of blunt cone forebody on the position of laminar-turbulent transition

D.A. Bountin, Yu.V. Gromyko, A.A. Maslov, P.A. Polivanov, and A.A. Sidorenko
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: hypersonic boundary layer, laminar-turbulent transition, surface roughness
Pages: 629638

Abstract >>
In the present paper, data on the effect of the surface roughness of blunt cone forebody on the position of laminar-turbulent transition are reported. The study was carried out under freestream Mach 5.95. It was found that the roughness position plays a substantial role in the transition process. Critical Reynolds numbers at which the laminar-turbulent transition occurs on the nose-tip of the model were identified. For the first time, hysteresis in transition position was observed.

DOI: 10.1134/S0869864316050012

Flow control of the semicircular airfoil with a vortex cell at slot suction of air and its blowout into the near wake

S.A. Isaev, P.A. Baranov, M.Yu. Smurov, A.G. Sudakov, and A.V. Shebelev
St.-Petersburg State University of Civil Aviation, St. Petersburg, Russia
Keywords: vortex cell, semicircular airfoil, suction, fan, multi-block computer technologies, modified MSST
Pages: 639643

Abstract >>
In the vicinity of a semicircular airfoil with slot suction of air provided with a 0.2-diameter (chord) vortex cell installed on the backside of the wing, at low speeds and zero angle of attack the pattern of the unsteady separated airflow undergoes substantial changes, those changes being accompanied with the displacement of flow separation point toward the trailing edge. The slot suction of air and its blowout into the near wake in such an airfoil is organized using a discharge channel with a fan; from this channel, the air jet is discharged into atmosphere tangentially to the airfoil base, with the pressure drop in the fan being equal to twice the pressure head. Under such conditions, the integral force characteristics of the wing show dramatic changes: the lift force, initially being ultra-low negative, becomes positive, and the drag decreases two-fold. The static pressure decreases by two or three times on the upper arch of the profile, and it increases by two times on the lower part of the airfoil, the level of pressure pulsations decreasing by more than ten times.

DOI: 10.1134/S0869864316050024

Investigation of annular supersonic inlets with isentropic compression

V.M. Galkin1, V.I. Zvegintsev2, and D.A. Vnuchkov2
1Tomsk Polytechnic University, Tomsk, Russia
2Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: nozzle, the method of characteristics, axisymmetric supersonic flow, ideal gas, reversed flow, the inlet start, viscous flow
Pages: 645655

Abstract >>
A technique for designing the supersonic annular inlets with isentropic deceleration surfaces is considered. The contour of an isentropic supersonic nozzle constructed by the method of characteristics for an inviscid gas flow with given uniform parameters at the inlet and at the outlet is used as the basic configuration of the inlet. The reversed flow of a viscous gas is computed with the aid of numerical techniques in the contour under consideration and the real operational characteristics of the obtained inlet of a fixed geometry are determined in the range of the conditions of its application. In the process of computations, the minimum cross-sectional sizes are selected, which ensure the inlet start without a detached bow shock at the entrance.

DOI: 10.1134/S0869864316050036

Experimental investigation of wake evolution behind a couple of flat discs in a hydrochannel

I.V. Naumov1, I.V. Litvinov1, R.F. Mikkelsen2, and V.L. Okulov1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Technical University of Denmark, Lyngby, Denmark
Keywords: wake behind a bluff body, level of turbulence of the incident flow, pair of discs, velocity deficit, Particle Image Velocimetry (PIV)
Pages: 657666

Abstract >>
The decay of a far wake and its turbulent fluctuations behind two thin discs of the same diameter D, oriented normal to the incident flow, have been studied using the Particle Image Velocimetry (PIV). The experimental study was carried out in a water flume (Re ≈ 2⋅105) with varying distances between the discs (Lx = 48D) and their axes shift relative to each other (0, 0.5D and 1D). It is found that the velocity deficit behind two discs depends weakly on Lx, and at L > 40D, it becomes indistinguishable from the level of turbulent fluctuations of the incident flow. It is found that the decay of the average velocity deficit and its turbulent fluctuations in a wake of a tandem of discs can be described by the same analytical dependence with exponent -2/3 as for the wake decay of a single disc. However, at the same distance downstream, the value of deficit behind two discs is substantially higher than the corresponding value behind a single disc. Velocity fluctuations in a far wake behind a pair of discs depend weakly on longitudinal dimension Lx, but at the same time, in contrast to the velocity deficit, their level does not differ significantly from the level of fluctuations behind a single disc.

DOI: 10.1134/S0869864316050048

Numerical modeling of the swirling turbulent wake decay past a self-propelled body

A.G. Demenkov1,2 and G.G. Chernykh3,4,5
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
3Institute of Computational Technologies SB RAS, Novosibirsk, Russia
4Novosibirsk State University, Novosibirsk, Russia
5Siberian State University of Telecommunications and Information Sciences, Novosibirsk, Russia
Keywords: swirling turbulent wake past a self-propelled body, mathematical modeling, self-similar degeneration, shearless flow
Pages: 667675

Abstract >>
Numerical analysis of the swirling turbulent wake degeneration past a self-propelled body has been carried out. It has been shown that starting from the distances of the order of 100 diameters from the body, the flow becomes prac-tically shearless. A simplified mathematical model of the far swirling wake past a self-propelled body has been constructed.

DOI: 10.1134/S086986431605005X

Turbulent circulation above the surface heat source in a stably stratified environment

A.F. Kurbatskii1 and L.I. Kurbatskaya2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Institute of Computational Mathematics and Mathematical Geophysics SB RAS, Novosibirsk, Russia
Keywords: turbulence, planetary boundary layer, urban heat island, large-scale circulation, numerical modeling
Pages: 677692

Abstract >>
The results of the numerical modeling of turbulent structure of the penetrating convection above the urban heat island with a small aspect ratio in a stably stratified medium at rest are presented. The gradient diffusion representations for turbulent momentum and heat fluxes are used, which depend on three parameters - the turbulence kinetic energy, the velocity of its spectral expenditure, and the dispersion of temperature fluctuations. These parameters are found from the closed differential equations of balance in the RANS approach of turbulence description. The distri-butions of averaged velocity and temperature fields as well as turbulent characteristics agree well with measurement data.

DOI: 10.1134/S0869864316050061

Simulation of turbulent non-isothermal polydisperse bubbly flow behind a sudden tube expansion

M.A. Pakhomov and V.I. Terekhov
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: bubble separated flow, turbulence, heat transfer enhancement, simulation
Pages: 693699

Abstract >>
The results of numerical simulation of the structure of non-isothermal polydisperse bubbly turbulent flow and heat transfer behind a sudden tube expansion are presented. The study was carried out at a change in the initial dia-meter of the air bubbles within dm1 = 15 mm and their volumetric void fraction β = 010 %. Small bubbles are available in almost the entire cross section of the tube, while the large bubbles pass mainly through the flow core. An increase in the size of dispersed phase causes the growth of turbulence in the liquid phase due to flow turbulization, when there is a separated flow of liquid past the large bubbles. Adding the air bubbles causes a significant reduction in the length of the separation zone and heat transfer enhancement, and these effects increase with increasing bubble size and their gas volumetric flow rate ratio.

DOI: 10.1134/S0869864316050073

Numerical investigation of the variable nozzle effect on the mixed flow turbine performance characteristics

B. Meziri1,2, M. Hamel2, O. Hireche1,2, and K. Hamidou2
1Ecole nationale polytechnique dOran, El MNaouer, Oran, Algerie
2Universite des Sciences et de la Technologie dOran, El MNaouer, Oran, Algerie
Keywords: variable nozzle, design, mixed flow, turbine, turbocharger
Pages: 701711

Abstract >>
There are various matching ways between turbocharger and engine, the variable nozzle turbine is the most significant method. The turbine design must be economic with high efficiency and large capacity over a wide range of operational conditions. These design intents are used in order to decrease thermal load and improve thermal efficiency of the engine. This paper presents an original design method of a variable nozzle vane for mixed flow turbines developed from previous experimental and numerical studies. The new device is evaluated with a numerical simulation over a wide range of rotational speeds, pressure ratios, and different vane angles. The compressible turbulent steady flow is solved using the ANSYS CFX software. The numerical results agree well with experimental data in the nozzleless configuration. In the variable nozzle case, the results show that the turbine performance characteristics are well accepted in different open positions and improved significantly in low speed regime and at low pressure ratio.

DOI: 10.1134/S0869864316050085

Application of local indentations for film cooling of gas turbine blade leading edge

V.Yu. Petelchyts1, A.A. Khalatov2,3, D.M. Pysmennyi1, and Yu.Y. Dashevskyy1
1Gas Turbine Research and Production Complex Zorya-Mashproekt, Mykolaiv, Ukraine
2Institute of Engineering Thermophysics, National Academy of Sciences of Ukraine, Kyiv, Ukraine
3National Technical University of Ukraine I. Sikorskiy Kyiv Polytechnic Institute, Kyiv, Ukraine
Keywords: film cooling, blowing parameter, leading edge, cooling system, semi-spherical dimple, trench
Pages: 713720

Abstract >>
The paper presents results of computer simulation of the film cooling on the turbine blade leading edge model where the air coolant is supplied through radial holes and row of cylindrical inclined holes placed inside hemi-spherical dimples or trench. The blowing factor was varied from 0.5 to 2.0. The model size and key initial parameters for simulation were taken as for a real blade of a high-pressure high-performance gas turbine. Simulation was performed using commercial software code ANSYS CFX. The simulation results were compared with reference variant (no dimples or trench) both for the leading edge area and for the flat plate downstream of the leading edge.

DOI: 10.1134/S0869864316050097

Numerical approach to new tangential slot effect on film cooling effectiveness over asymmetrical turbine blade

Z. Senouci and M. Benabed
University of Science and Technologies, Oran, Algeria
Keywords: film cooling, tangential slot, coverage ratio, SST turbulence model
Pages: 721734

Abstract >>
The focus of this numerical study is to conceive a new basic film cooling configuration in order to increase film cooling effectiveness, especially at the leading edge zone between the injection holes where cooling is mostly needed. The new configuration, resulting from the tangential slot configuration and especially adapted to the leading edge of an asymmetrical blade, is compared to the uniform slot configuration. Three alternatives geometries were proposed and numerically tested to find the configuration that provides the best film cooling effectiveness. The simulation is conducted at a fixed density ratio of 1.0 and a blowing ratio of 0.7. A new parameter, Rc, is defined to measure the rate of blade coverage by the film cooling. The outcomes of the numerical results indicate that the three proposed configurations allow better thermal protection because of their higher film cooling coverage. At suction side, the new configurations provide a better film cooling coverage than the baseline case. The minimal improvement is at approximately 34%, with a light superiority of case 1. At pressure side, the use of the tangential slot is especially interesting for the allowed minimum adiabatic effectiveness values between 0.3 and 0.5.

DOI: 10.1134/S0869864316050103

Experimental study of cold gas spraying through a mask. Part 1

S.V. Klinkov, V.F. Kosarev*, N.S. Ryashin, and V.S. Shikalov
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: cold gas spraying, mask, coating profile, masked zone width
Pages: 735740

Abstract >>
The paper presents experimental data for production of a coating using cold gas dynamic spraying with a mask with transverse size in the range 0.3-1 mm and placed at different distances from the substrate. The coated samples were produced, and coating profiles were measured in the vicinity of the masked zone. The tests with depositing of aluminum powder and copper powder demonstrated that the distinct profile of masked zone is obtained for placing the mask at a distance below critical (depending of spray conditions). The most accurate boundary of the masked zone takes place at a minimal distance (depends on the coating thickness). Depending on the spraying conditions, the increase in the mask-substrate distance may result either in monotonic decline of the masked zone width or a slight increase for a certain range. Experimental data are generalized by normalizing with the transverse size of the mask (under other equal conditions).

DOI: 10.1134/S0869864316050115

Co-extraction of water vapor and helium from natural gas

V.N. Zinovyev, I.V. Kazanin, V.A. Lebiga, A.Yu. Pak, A.S. Vereshchagin, and V.M. Fomin
Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: composite sorbent, microspheres, permeability, helium, natural gas, drying, gas separation
Pages: 741746

Abstract >>
A study of the sorption properties of a composite sorbent prepared from pseudoboehmite and synthetic sodium-borosilicate glass microspheres was performed with the aim of using the sorbent in membrane-sorption processes of helium extraction from natural gas with its simultaneous drying. Experimentally, permeability of the composite sorbent under study with respect to helium and its impermeability to air and methane has been demonstrated. Under experimental conditions, the absolute moisture content of the gas mixture having passed through the sorbent has reduced from 21.1 to 0.013 g/m3. The rate of helium adsorption by the composite sorbent has increased nearly by two orders of magnitude in comparison with the initial microspheres. It was found that the degree of saturation of the sorbent with water vapor had almost no influence on the rate of helium adsorption. A possibility of optimal use of the composite sorbent by combining the process of natural-gas drying from water vapor and the process of helium extraction from natural gas is shown. This possibility permits shortening of the process sequence for natural gas pre-conditioning prior to helium extraction.

DOI: 10.1134/S0869864316050127

Selecting the optimum method of heat transfer intensification to improve efficiency of thermoelectric generator

A.I. Leontyev, D.O. Onishchenko, and G.A. Arutyunyan
Bauman Moscow State Technical University, Moscow, Russia
Keywords: thermoelectric generator, internal combustion engine, heat transfer intensification, energy of exhaust gases
Pages: 747754

Abstract >>
The relevance of applying the methods of energy recovery from exhaust gases is substantiated. The principle of operation of a thermoelectric generator is described, the variant of its design is proposed, and the efficiency of various design methods of heat exchange intensification is compared. Designs are compared with a baseline configuration without heat transfer intensifiers in terms of coefficients of gas dynamic resistance ξ/ξ0 and the ratio of dimensionless criteria Nu/Nu0. The results of comparative analysis have proved the applicability of the methods of heat exchange intensification in the design of thermoelectric generators of various vehicles.

DOI: 10.1134/S0869864316050139

Studying regimes of convective heat transfer in the production of high-temperature silicate melts

O.G. Volokitin1, M.A. Sheremet2, V.V. Shekhovtsov1, N.S. Bondareva2, and V.I. Kuzmin3
1Tomsk State University of Architecture and Construction, Tomsk, Russia
2Tomsk State University, Tomsk, Russia
3Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
Keywords: plasma technology, silicate melt, mathematical model, heat transfer, non-Newtonian medium
Pages: 755765

Abstract >>
The article presents the results of theoretical and experimental studies of the production of high-temperature silicate melts using the energy of low-temperature plasma in a conceptually new setup. A mathematical model of unsteady regimes of convective heat and mass transfer is developed and numerically implemented under the assumption of non-Newtonian nature of flow in the melting furnace with plasma-chemical synthesis of high-temperature silicate melts. Experiments on melting silicate containing materials were carried out using the energy of low-temperature plasma. The dependence of dynamic viscosity of various silicate materials (basalt, ash, waste of oil shale) was found experimentally.

DOI: 10.1134/S0869864316050140

Investigation of energy parameters of the plasma-resistive furnace

A.S. Anshakov1,2, A.I. Aliferov2, and P.V. Domarov1,2
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: plasma-resistive furnace, plasmatorch, mathematical model, man-made waste, plasma heating, resistance heating
Pages: 767772

Abstract >>
The electrical and thermal characteristics of plasma-resistive furnace in the drying zone at a recycling man-made waste were studied. The dependences of power output in the drying zone at different specific electrical resistances of the charge were derived. It is shown that introduction of additional resistance heating in the drying zone reduces the load on plasmatorch, increasing the lifetime of electrodes.

DOI: 10.1134/S0869864316050152

On laminar-turbulent transition in nanofluid flows

V.Ya. Rudyak1, A.V. Minakov1,2,3, D.V. Guzey1,2, V.A. Zhigarev2, and M.I. Pryazhnikov1,2
1Novosibirsk State University of Architecture and Civil Engineering, Novosibirsk, Russia
2Siberian Federal University, Novosibirsk, Russia
3Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: nanofluid, laminar-turbulent transition, nanoparticles, flow in pipe, hydrodynamic resistance, viscosity
Pages: 773776

Abstract >>
The paper presents experimental data on the laminar-turbulent transition in the nanofluid flow in the pipe. The transition in the flows of such fluids is shown to have lower Reynolds numbers than in the base fluid. The degree of the flow destabilization increases with an increase in concentration of nanoparticles and a decrease in their size. On the other hand, in the turbulent flow regime, the presence of particles in the flow leads to the suppression of small-scale turbulent fluctuations. The correlation of the measured viscosity coefficient of considered nanofluids is presented.

DOI: 10.1134/S0869864316050164

Calculating heat transfer in liquid films based on the method of weighted residuals

S.P. Aktershev and M.V. Bartashevich
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: liquid film, heat transfer, semi-analytical method
Pages: 777780

Abstract >>
The application of the weighted residuals method is considered for the calculation of heat transfer in flowing thin liquid films. As an example, the problem of the film moving under the action of the gas flow on the heated horizontal wall is solved. The solution demonstrates good agreement with the numerical one obtained by the finite-difference method.

DOI: 10.1134/S0869864316050176

Comparative analysis for performance of brown coal combustion in a vortex furnace with improved design

D.V. Krasinsky
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: vortex furnace for steam boiler, numerical modelling, coal combustion
Pages: 781784

Abstract >>
Comparative study of 3D numerical simulation of fluid flow and coal-firing processes was applied for flame combustion of Kansk-Achinsk brown coal in a vortex furnace of improved design with bottom injection of secondary air. The analysis of engineering performance of this furnace was carried out for several operational modes as a function of coal grinding fineness and coal input rate. The preferable operational regime for furnace was found.

DOI: 10.1134/S0869864316050188

70th Anniversary of Anatoly A. Maslov

Editorial Board
Siberian Branch of the RAS, Novosibirsk, Russia
Pages: 785786

Abstract >>
August 7, 2016 is the 70th Anniversary of Professor Anatoly A. Maslov, a noted scientist, specialist in viscous gas dynamics, and Doctor of physical and mathematical sciences.

DOI: 10.1134/S086986431605019X

50th Anniversary of Alexander N. Shiplyuk

Editorial Board
Siberian Branch of the RAS, Novosibirsk, Russia
Pages: 787788

Abstract >>
September 8, 2016 is the 50th Anniversary of Alexander N. Shiplyuk, a noted scientist, researcher in the field of high-velocity aerogasdynamics and experimental methods of studying gas flows, doctor of physical and mathematical sciences, corresponding member of the Russian Academy of Sciences.

DOI: 10.1134/S0869864316050206

In memory of Anatoly M. Kharitonov

Editorial Board
Siberian Branch of the RAS, Novosibirsk, Russia

Abstract >>
Professor Anatoly M. Kharitonov, an outstanding researcher in the domain of fluid mechanics, doctor of technical sciences, Honored scientist of the Russian Federation, winner of the Prize of the Council of Ministers of the USSR and of the Prize named after Professor N.E. Zhukovskii, and Deputy Editor-in-Chief of our journal, deceased on August 13, 2016.

DOI: 10.1134/S0869864316050218