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Thermophysics and Aeromechanics

2010 year, number 3

Energy characteristics of Darrieus rotor (review)

D.N. Gorelov
Keywords: Darrieus rotor, ideal wind turbine, experimental studies of Darrieus rotor
Pages: 314-321

Abstract >>
Presented below is the review of the results of experimental studies of energy characteristics of Darrieus rotor with vertical rotation axis. Influence of main geometry parameters of the rotor on its energy characteristics has been analyzed. It is shown that Darrieus rotor may have the higher level of energy characteristics than the best propeller wind turbines.

Modelling of turbulent boundary layers on the body of revolution in the presence of large eddy breakup devices

V.I. Kornilov, E.A. Shkvar
Keywords: computation, algebraic-differential model, turbulent boundary layer, body of revolution, eddy breakup devices, experiment
Pages: 323-334

Abstract >>
A novel approach was proposed to developing a combined algebraic-differential model of turbulent viscosity, which was then used to modify the traditional method for calculating turbulent boundary layers on bodies of revolution immersed in an incompressible flow. Ample experimental data were invoked to test the developed model through prediction of features inherent in turbulent boundary layers on the body of revolution in the presence of Large Eddy BreakUp (LEBU) devices installed in the vicinity of the streamlined surface. Within the developed approach, we showed it possible to calculate the evolution of local governing characteristics of turbulent flow in a broad range of LEBU parameters.

Structure of the channel flow behind a surface-mounted rib under conditions of laminar-turbulent transition

O.A. Dushina, V.M. Molochnikov, A.A. Paereliy, N.I. Mikheev, V.V. Lemanov
Keywords: laminar-turbulent transition, heat transfer augmentation, large-scale vortical structures, PIV measurements, flow structure
Pages: 335-345

Abstract >>
The PIV technique was used to measure the instantaneous vector fields of flow velocity and vorticity behind a thin cross-flow rib installed in a channel with laminar, transient, or turbulent flow. The data were treated statistically to determine the fields of mean longitudinal flow velocity and the correlations of pulsating velocity components 〈uv′〉 and 〈uu′〉. Some features of the flow structure developing under conditions of laminar-turbulent transition behind the rib have been revealed.

Gas flow in domain with cubic package of spheres

A.M. Lipanov, A.N. Semakin
Keywords: viscous gas, system of fluid mechanics equations, cubic package of spheres
Pages: 346-351

Abstract >>
Viscous gas flow in the domain with a cubic package of spheres is considered. The problem formulation and the solution method are briefly presented. The integral parameters are presented, and the flow character is identified.

Regular waves on vertical falling rivulets at different wetting contact angles

S.V. Alekseenko, A.V. Bobylev, V.V. Guzanov, D.M. Markovich, S.M. Kharlamov
Keywords: rivulet, contact wetting angle, regular waves, laser-induced fluorescence
Pages: 352-364

Abstract >>
Results of experimental investigation of regular wave conditions for straight rivulets falling down a vertical plane are presented. Field measurements of the local thickness of rivulets were carried out with the help of laser-induced fluorescence. Data on the wave structure of rivulets is shown in a wide range of frequencies of regular waves for different Reynolds numbers of the flow and contact wetting angles. It was observed for all studied wave conditions that transverse width of rivulets and wetting angles are insensitive to the phase of propagating waves. Moreover, it was found that the wave structure of rivulets differs significantly for the cases of low and high values of the contact angle.

Heat transfer in falling laminar-wavy liquid films

S.P. Aktershev
Keywords: falling liquid film, waves, heat transfer
Pages: 365-375

Abstract >>
Heat transfer in the laminar-wavy film of liquid falling over the heated plate is studied numerically. To describe the wavy film flow the integral model is applied. Calculation results demonstrate the effect of physical properties of liquid and wavy flow parameters on heat transfer intensification by stationary running waves.

Modelling of pressure pulse evolution at the contact of cold liquid with saturated vapor

S.I. Lezhnin, A.L. Sorokin
Keywords: saturated vapor, intensive condensation, rarefaction wave
Pages: 376-379

Abstract >>
The process of rarefaction wave propagation in saturated vapor at sudden contact with cold liquid is studied.

Modelling of decomposition of a single gas hydrate particle in water behind the shock wave front

S.D. Sleptsov, V.E. Dontsov
Keywords: phase transition, shock wave, gas hydrate, methane
Pages: 380-385

Abstract >>
The mathematical model of decomposition of a spherical gas hydrate particle in water behind a 1D wave of the stepped profile (rarefaction wave) is suggested. Contribution of the outer and inner heat flux in a particle to the process of hydrate decomposition is studied. The effect of the gas hydrate particle size, pressure and temperature jumps in liquid on gas hydrate decomposition is investigated.

Crystallization dynamics of metallic droplet modified with nanoinoculators at its impact with substrate

A.N. Cherepanov, V.N. Popov, O.P. Solonenko
Keywords: plasma spraying, droplet impact with substrate, crystallization kinetics, supercooling
Pages: 386-393

Abstract >>
A physical and mathematical model is developed, and numerical studies are carried out to investigate the processes of non-equilibrium crystallization of a metallic liquid droplet modified with refractory solid nano-inclusions at its impingement on a solid substrate. The conditions are considered, which are typical of thermal spraying of metal coatings, including the plasma spraying. An analysis of the splat formation depending on the concentration of refractory nanoparticles within the metallic droplet volume, their size and substrate temperature is given. The characteristics of splats computed using the non-equilibrium and equilibrium models of crystallization are compared under the same remaining conditions. The conditions of applicability of models are discussed.

The density and the binary diffusion coefficients of silver-tin melts

R.A. Khairulin, S.V. Stankus, R.N. Abdullaev, YU.A. Plevachuk, K.YU. Shunyaev
Keywords: density, diffusion, melt, silver-tin system, gamma-method
Pages: 394-399

Abstract >>
Temperature dependences of the density of liquid silver-tin melts containing 61.6 and 96.5 wt. % Sn (59.3 and 96.15 at. % Sn) have been determined using gamma-ray attenuation technique over the temperature range from liquidus line to 950 K. The density changes during solid-liquid transition have been directly measured for the first time for eutectic alloy (96.5 wt. % Sn). The temperature and concentration dependences of the thermal properties for Ag-Sn system have been constructed. Kinetics of homogenization of the melts with mean composition of 61.6 wt. % Sn has been investigated in the temperature range from 770 to 950 K. The coefficients of binary diffusion have been derived from these experiments.

Electric-arc plasma-chemical reactors of separated, single-chamber, and combined types

B.I. Mikhailov
Keywords: electric-arc plasmatorch, plasma chemistry, plasma-chemical reactor, plasma-forming medium, classification, lifetime, power, thermal efficiency, reaction zone, powder fraction, refractory, scanning, V-shape arc, liquid-metal electrode, manufacturability,
Pages: 400-412

Abstract >>
A wide variety of electric-arc reactors are involved in different areas of science and technologies. Therefore, a demand arose for their systematization. Here we present the classification of most existing types of electric-arc reactors regarding the mutual positioning of plasma-generation and reaction zones. There are three types of reactors: separated, single-chamber, and combined type. Different engineering solutions in each type led to some scatter in the thermal efficiency, power range, lifetime, and other results. No consideration has been given to the reactors of single-chamber heating. They are very special and require individual researches.

Analysis of energy balance of the arc discharge limited by walls

E.N. Vasiliev
Keywords: arc discharge, heat exchange, radiation regime, channel model
Pages: 413-421

Abstract >>
The modeling of the formation of the equilibrium arc discharge structure in the axisymmetric formulation was carried out in a wide range of the values of current and radius. The boundary separating the radiation and heat-conducting regimes of discharge combustion was determined from computed data. The influence of energy mechanisms on the structure of the discharge was analysed, and a channel model was proposed for computing its parameters in the radiation regime.

Numerical simulation of laser welding of thin metallic plates taking into account convection in the welding pool

V.I. Isaev, V.P. Shapeev, A.N. Cherepanov
Keywords: mathematical modelling, numerical methods, Navier - Stokes equations, heat and mass transfer, laser welding of metals, Stefan problem
Pages: 422-435

Abstract >>
A new quasi-three-dimensional model of the laser welding of thin metal plates and a numerical algorithm of its implementation are proposed. Computations of thermophysical processes at a laser joining of titanium plates are carried out. It is shown that the new model adequately describes thermophysical and hydrodynamic processes occurring in the welding region.

Pulverized coal torch combustion in a furnace with plasma-coal system

V.E. Messerle, A.B. Ustimenko, A.S. Askarova, A.O. Nagibin
Keywords: combustion, pulverized coal, plasma, boiler furnace, three-dimensional simulation, model verification
Pages: 436-444

Abstract >>
Combustion of a pulverized coal torch has been numerically simulated on the basis of the equations of multicomponent turbulent two-phase flows. The results of three-dimensional simulation of conventional and plasma activated coal combustion in a furnace are presented. Computer code Cinar ICE was verified at coal combustion in the experimental furnace with thermal power of 3 MW that was equipped with plasma-fuel system. Operation of the furnace has been studied at the conventional combustion mode and with plasma activation of coal combustion. Influence of plasma activation of combustion on thermotechnical characteristics of the torch and decrease of carbon loss and nitrogen oxides concentration at the furnace outlet has been revealed.

75th Anniversary of Vladimir E. Nakoryakov

Editorial board
Pages: 445-446

Abstract >>
On June 26, 2010  Vladimir V. Nakoryakov  the prominent Russian scientist working in the area of thermophysics, the Full Member of the Russian Academy of Sciences  became 75 years of age.

75th Anniversary of Robert I. Nigmatullin

Editorial board
Pages: 447-448

Abstract >>
On June 17, 2010  Robert I. Nigmatulin  the prominent scientist specialized in mechanics and mathematics, the Full Member of the Russian Academy of Sciences  became seventy years of age.

60th Anniversary of Sergey V. Alekseenko

Editorial board
Pages: 449-450

Abstract >>
On May 30, 2010  the Corresponding Member of the Russian Academy of Sciences, the Director of the Institute of Thermophysics SB RAS  Sergey V. Alekseenko  was 60 years of age.

75th Anniversary of Anatoliy P. Burdukov

Editorial board
Pages: 451-452

Abstract >>
On June 26, 2008  Professor Anatoly P. Burdukov  the Laureate of the State Prize in Science and Engineering, the Honored Worker of Russian Science  was 75 years of age.