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Thermophysics and Aeromechanics

2012 year, number 6

A numerical and experimental study of the high-enthalpy high-speed cavity flow

M.A. Goldfeld1,2, Yu.V. Zakharova1,2, and N.N. Fedorova2
1Khristianovich Institute of Theoretical and Applied Mechanics SB RAS, Novosibirsk, Russia
2Novosibirsk State University of Architecture and Civil Engineering, Novosibirsk, Russia
Keywords: high-speed, high-enthalpy flows; apparatus channels; cavity; turbulence; experiment; mathematical modeling
Pages: 673-687

Abstract >>
Results of an experimental and numerical study of supersonic turbulent high-enthalpy flow in a channel with cavity are reported. On the basis of wind-tunnel tests performed in the IT-302M short duration wind tunnel, data on the flow structure and on the distribution of static pressure along the model walls were obtained. These data were subsequently used to verify the numerical algorithm. In the calculations, a parametric study of the effects of Mach number, cavity configuration, and temperature factor on flow quantities was performed. It was numerically shown that variation of the above parameters leads to a transition of the flow regimes in the vicinity of the cavity.

Experimental study of temperature field evolution in the channel with corrugated wall at a jump-like change in the heat flux

B.V. Perepelitsa
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: temperature, nonstationary heat transfer, turbulence, wall, ribs, flow, heat exchanger
Pages: 689-696

Abstract >>
Results of experimental investigation of nonstationary temperature field in the flow and on the surface of the channel with corrugated wall are presented at a jump-like change of heat release in time. The changes were performed at the air flow in a rectangular channel, whose one heated wall was made as a plate with triangular corrugation oriented at 45º relative to the main flow direction. The microthermocouples with the thickness of below 10 microns were used to perform these changes. Investigations revealed typical regularities of temperature evolution in the flow and along the perimeter of the heated rib. Experimental data on time-temperature dependence are approximated well by the exponential function.

MHD free convection flow over an isothermal vertical cone with temperature dependent viscosity

E. Thandapani1, A.R. Ragavan2, and G. Palani2
1University of Madras, Tamil Nadu, India
2Dr. Ambedkar Govt. Arts College, Tamil Nadu, India
Keywords: apex, magnetohydrodynamics, MHD, finite difference, Nusselt number, vertical cone, variable viscosity
Pages: 697-710

Abstract >>
Free convection flow over an isothermal vertical cone immersed in a fluid with variable viscosity and MHD is studied in this paper. Using appropriate variables, the basic equations are transformed into the non- dimensional boundary-layer equations. These equations are then solved numerically using a very efficient implicit finite-difference method known as Crankl—Nicolson scheme. Detailed results for the velocity, temperature, skin friction, and heat transfer rates for a selection of parameter sets consisting of the viscosity parameter, magnetic field parameter, and Prandtl number are discussed. In order to validate our numerical results, the present results are compared with the available work in the literature and are found to be in an excellent agreement.

Mathematical simulation of liquid film flows with “dry” spots

L.I. Maltsev and D.S. Zavarzin
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: falling liquid film, film disruption, dry spot, simulation
Pages: 711-718

Abstract >>
Mathematical simulation of isothermal film flow for a viscous ponderous capillary liquid with dry spots on a solid substrate was performed. The algorithm was developed for calculation of the shape of a ridge (around the dry spot): this algorithm takes into account gravity forces, surface tension, friction, and inertia effects. Simulation results performed by original method were compared with experiment and previous method that takes into account only gravity and capillary forces. It was demonstrated that both methods produce similar results at low Reynolds numbers. However, at Reynolds higher than one these two methods give different results.

Electric arc plasmatorch for steam heating

A.S. Anshakov1,2, S.I. Radko2, E.K. Urbakh1, A.E. Urbakh1, and V.A. Faleev1
1Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: plasmatorch, steam, tubular electrode, electric field strength, energy curves
Pages: 761-763

Abstract >>
A construction arrangement of electric arc plasmatorch with copper tubular electrodes for steam plasma generation was developed and tested. Experimental data on energy curves of this plasmatorch with nominal power of 100 kW are presented.

Modern problems of thermodynamics

I.I. Novikov
Baikov Institute of Metallurgy and Material Science RAS, Moscow, Russia
Keywords: power engineering, internal electrolysis, atomic energy, thermonuclear reactor, combined cycles, electronic and ionic chains
Pages: 765-767

Abstract >>
The role of energy and methods of its saving for the development of human society and life are analyzed. The importance of future use of space energy flows and energy of water and air oceans is emphasized. The authors consider the idea of the unit for production of electric energy and pure substances using sodium chloride which reserves are limitless on the planet. Looking retrospectively at the development of power engineering from the elementary fire to modern electric power station, we see that the used method of heat production, namely by direct interaction of fuel and oxidizer, is the simplest. However, it may be possible to combust coal, i.e., carbon in salt melt, for instance, sodium chloride that would be more rational and efficient. If the stated problems are solved positively, we would master all energy properties of the substance; and this is the main problem of thermodynamics being one of the sciences on energy.

Classical theory of homogeneous nucleation in superheated liquids and its experimental verification

G.V. Ermakov, E.V. Lipnyagov, and S.A. Perminov
Institute of Thermophysics UB RAS, Yekaterinburg, Russia
Keywords: metastable states at phase transitions of the first type, superheated liquids, classical theory of homogeneous stationary nucleation in superheated liquids, experimental methods for determination of inhomogeneity and nonstationarity of superheated liquids boiling-up, video filming of superheated liquids boiling-up
Pages: 769-780

Abstract >>
This work summarizes the cycle of investigations devoted to determination of the character of superheated liquid boiling-up in a glass capillary at the boundary of the attainable superheating. The brief history of studies is followed by a brief introduction into the theory of homogeneous nucleation. The result of the targeted experiments determining stationarity of a random process of a supercritical embryo generation is considered. From the experiments it may be concluded that the process is unsteady. Based on a large selection of life spans of superheated liquids, the authors have made parametric and nonparametric evaluations of the functions of distribution and dependence of boiling-up frequency on time. The comparison of the obtained results with exponential distribution shows significant differences that also prove the nonstationarity of the studied random process. Special experiments and calculations for evaluation of homogeneity of the superheated liquid boiling-up at the boundary of attainable superheating are considered. It is shown that in the experiments with glass capillary, the boiling-up occurs on the wall. As the most convincing evidence of heterogeneity of the superheated liquid boiling-up in a glass capillary the authors provide the results of high-speed video filming in a silylated and clean capillaries.

Description of SF6 behavior within the state range from the triple point to supercritical fluid

P.P. Bezverkhy1, V.G. Martynets1, E.V. Matizen1, A.B. Kaplun2, and A.B. Meshalkin2
1Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk, Russia
2Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: SF6, combined equation of state, critical point, heat capacity
Pages: 781-791

Abstract >>
Р-ρ data of SF6 were approximated by the combined equation of state within the ranges of reduced densities (0 < ρ /ρc < 2.5) and temperatures (225 < Т < 340 K). The equation of state, which has the form of explicit dependence of pressure Р on r and T, includes a new regular part for approximation of Р-ρ data in liquid an gaseous ranges of states beyond the critical region, nonparametrical scaling equation of state valid near the critical point of evaporation, and new crossover function for combination of these equations. The regular part of combined equation of state includes 8 simple terms of equation with eight adjustable parameters, three of which are determined by the conditions at the critical point. The total number of system-dependent constants is 14, including the critical values of Рρ, and Т. For the scaling part of state equation, the critical indices of 3D Ising model are used. At approximation of high-accuracy Р-ρ data of SF6 by the new combined equation their description with the pressure error below ± 0.35 % was obtained in the whole range of gas and liquid states. Heat capacity Cν was calculated on the critical isochore using constants of combined equation. Calculation results coincide with the known experimental data within their error limit. The behavior of Cν on isotherms was predicted in a wide range of densities, and these data were compared with predictions of other modern equations of state.