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Thermophysics and Aeromechanics

2009 year, number 4

The state and prospects of coal and nuclear power generation in Russia (review)

V.V. Salomatov
Keywords: energy carrier, coal power engineering, nuclear power engineering, electricity, "roadmap"
Pages: 531-544

Abstract >>
Data on the modern state and development trends for coal and nuclear power engineering in Russia up to 2030 are generalized. It is emphasized that from the viewpoint of strategy, coal and uranium fuel will be the main energy carriers. The forecast of energy consumption is made; the "roadmap" of new power-generating units of heat and nuclear power plants on the territory of Russia is presented.

Investigation of coal fired combined-cycle cogeneration plants for power, heat, syngas, and hydrogen

V.E. Nakoryakov, G.V. Nozdrenko, A.G. Kuzmin
Keywords: combined cycle plant, coal gasifier, syngas, hydrogen
Pages: 545-551

Abstract >>
The methodology for determination of technical and economic efficiency of coal fired combined-cycle cogeneration plant (CCCP) with low-pressure steam-gas generator and continuous flow gasifier at combined production of power, heat, syngas, and hydrogen is considered. The results of investigation are presented. Such CCCP have higher technical and economic efficiency than the pulverized coal cogeneration plant modified by gas-turbine.

Development and application of a diffusion-inertia model for simulating gas-dispersed turbulent flows

N.I. Drobyshevsky, L.I. Zaichik, R.V. Mukin, V.F. Strizhov, A.S. Filippov
Keywords: turbulent gas-dispersed flow, aerosol particles, modeling, deposition
Pages: 553-572

Abstract >>
The development and application of a diffusion-inertia model are shown for computing the propagation and deposition of aerosol particles in turbulent flows. Comparison with experimental and numerical results points to the fact that the developed model adequately describes all the typical peculiarities of the process of the sedimentation of aerosol particles in straight and curved pipes.

An experimental study of the forerunners of boundary-layer localized disturbances at an enhanced turbulence level

V.N. Gorev, M.M. Katasonov, V.V. Kozlov, P.A. Motyrev
Keywords: laminar-turbulent transition, high free-stream turbulence, forerunners, longitudinal structures
Pages: 573-581

Abstract >>
Turbulence production processes in boundary layer at a high level of free-stream turbulence have been studied. The tests were carried out in the MT-324 subsonic wind tunnel of ITAM, SB RAS, on models of straight and 45° swept wings at Reynolds numbers Rec1 = 97000 and Rec2 = 137000, and also at low (Tu = 0.18 % U) and high (Tu = 0.79 and 2.31 % U) levels of free-stream turbulence. The longitudinal localized disturbances developing in the boundary layer under the action of free-stream turbulence were artificially modeled using local air suction through a slot on the model surface. Wave packets, or forerunners, produced in the boundary layer, in the region preceding the abrupt local change of flow velocity near the localized-disturbance fronts, were examined. The high level of free-stream turbulence was found to accelerate the downstream evolution of the wave packets and their transformation into turbulent spots.

On the vertical large eddy breakup device capability to decrease the turbulent drag

A.V. Boiko, V.I. Kornilov
Keywords: decrease in turbulent friction, vertical elements, incompressible turbulent boundary layer, flat plate
Pages: 583-596

Abstract >>
The possibility of decreasing the turbulent friction with the use of streamwise-aligned vertical large eddy breakup devices installed normal to the surface of a flat plate in an incompressible equilibrium turbulent boundary layer with a nominally gradientless flow past this plate is studied experimentally. The Reynolds number based on the boundary-layer momentum thickness is 1099 in the cross section where these vertical devices are mounted. It is shown that elements of this geometry are effective tools for modification of the turbulent boundary layer from the viewpoint of both the gain in friction drag and the suppression of turbulent fluctuations of velocity and, hence, can be considered as one of the most important factors of controlling the structure of the near-wall turbulence in the flow past a flat surface.

Effect of small total pulse on development of a wake behind the self-propelled bodies

B.G. Novikov
Keywords: hydrodynamic wakes, co-current flows, self-similarity, modeling, stereometry, approximation, propellers, turbulence
Pages: 597-623

Abstract >>
Experimental studies on the wakes behind the self-propelled bodies of revolution have been analysed, and results of stereometric studies on the co-current flows behind autonomous streamlined and bluff bodies of revolution are presented for the times of their development corresponding to the coordinate system of a distant wake of 2400 and 1200 body diameters, correspondingly. Possible modelling of axisymmetric co-currents by the flows generated by a string at its pulse motion along the axis is examined. It is shown that supposed solutions based on the model of interferential development of wakes behind the self-propelled bodies of revolution can approximate both the known results of experimental studies of wakes behind the self-propelled bodies of revolution and the flows generated by corresponding pulse transportation of a string.

Laser flash method for measurement of liquid metals heat transfer coefficients

S.V. Stankus, I.V. Savchenko
Keywords: laser flash technique, mercury, measurement technique, thermal diffusivity, thermal conductivity
Pages: 625-632

Abstract >>
New laser flash technique for the measurement of heat transfer coefficients of liquid metals is presented. The thermal diffusivity of the liquid mercury has been studied experimentally over the room temperature range. The thermal conductivity coefficient has been calculated with the use of the reference data on density and heat capacity. Analysis of systematic errors of the measurements has shown that the data error is about 3%. Comparison of the obtained results with data available in publications has proved their reliability.

Experimental determination of superheated liquids boiling-up expectancy time probabilities distribution

E.V. Lipnyagov, S.A. Perminov, G.V. Ermakov, B.M. Smolyak
Keywords: superheated (metastable) liquid, boiling-up expectancy time, non-exponential density of probability distribution, non-stationary nucleation
Pages: 633-640

Abstract >>
Results of statistical measurement of n-pentane and n-hexane boiling-up expectancy time near the boundary of attainable superheating are presented. Experiments were carried out in glass capillaries with various volumes of superheated liquid. Several samples with the volume from 100 to 200 measurements of life time for preset metastable state have been obtained (p, T = const). Their histograms contain small empty initial section, maximum and long "tail" in the area of large times. Non-monotonous dependence of probability distribution density on time proves non-stationary character of the random process resulting in the production of supercritical embryo. Two simple approximations of non-stationary nucleation flow well describing experimental data have been considered. For exponential distribution, the probabilities of experimentally found peculiarities of boiling-up expectancy time distribution density have been evaluated; they prove incompatibility of this distribution with the experimental one.

Numerical simulation of radiative-convective heat transfer at streamlining of the semitransparent film of melt

N.A. Rubtsov, V. A. Sinitsyn
Keywords: radiation, turbulence, boundary layer, film, scattering
Pages: 641-648

Abstract >>
Nonstationary radiative-convective heat transfer was simulated at turbulent streamlining of a semitransparent film of melt on a flat plate by the gas mixture and solid particles. The moving film is subjected to intensive radiation heating by an external source radiating within a limited spectral range. The temperature and velocity fields are calculated in the boundary layer and in the film. Calculation results allow determination of the effect of source temperature and film initial heating on dynamics of temperature and velocity fields of the medium in the boundary layer-film system.

Direct conversion of solid hydrocarbons in a molten carbonate fuel cell

M.R. Predtechensky, YU.D. Varlamov, S.N. Ul'yankin, YU.D. Dubov
Keywords: fuel cell, molten carbonate, electrochemical oxidation, solid hydrocarbons
Pages: 649-660

Abstract >>
Electrical characteristics of a molten carbonate fuel cell allowing direct electrochemical oxidation of dispersed hydrocarbons have been examined. As the fuel, graphite, anthracite, and cannel coal samples were used. Data illustrating the effect of electrolyte temperature, fuel type and dispersion, and also reactant gas mixture composition on the performance characteristics of the fuel cell, were obtained. Correlation between the specific characteristics of the fuel cell and the hydrogen content of fuel material was established. The maximum current-density values were achieved with hydrogen-rich cannel coal. For dispersed fuel samples, inter-particle contact losses were found to have influence on the cell-generated voltage. The maximum cell open-circuit voltage was reached with stoichiometric oxygen-carbon dioxide mixture blown into the cathode. Yet, the largest current-density values were obtained when carbon dioxide lean mixtures were used. Even at zero carbon dioxide concentration the range of cathode polarizations was less than that observed with stoichiometric mixture. The processes proceeding in the cathode and anode packs of the fuel cell are believed to be inter-related processes. In a model fuel cell fueled with dispersed coal, current densities up to 140 mA/cm2 and specific powers up to 70 mW/cm2 were achieved.

Study on the plasma treatment of waste oil containing PCB

H.S. Park, V.P. Lukashov, S.P. Vashchenko, S.V. Morozov
Keywords: plasmatorch, plasma chemistry, polychlorinated biphenyls, ash after waste incineration, dioxins, ecology, chromatography-mass-spectrometry
Pages: 661-670

Abstract >>
The paper presents the results of treatment of transformer oil containing less than 2 ppm polychlorinated biphenyls (PCB) in a plant of high-temperature plasma melting of ash residues after the municipal waste incineration. The content of undecomposed PCBs, dioxins, and other hazardous waste in all secondary products of treatment (off gases; slag; secondary fly ash; process water used for slag granulation) was analyzed by different methods. Performed analytical investigations showed high ecological degree of PCB decomposition in the plant of plasma-thermal treatment of ashes after incinerators.

Numerical and analytic investigation of the work process in the combustor of low-thrust liquid-propellant engine

F. Ommi, K. Nekofar
Keywords: combustor of the liquid-propellant engine (LPE), injector, work process, low thrust
Pages: 671-677

Abstract >>
The processes of spraying by the gas-liquid injector head of the low-thrust liquid-propellant engine combustor are investigated on model components (air and water) using the noncontact diagnostics methods based on laser sources. New quantitative dependencies are obtained for the influence of various factors and parameters on the spraying characteristics.

Modelling of turbulent flows in transonic axial-flow compressor NASA Rotor 37 with local weak-equilibrium damping of eddy viscosity coefficient

A.N. Aksyonov, A.B. Shabarov
Keywords: turbulence, eddy viscosity damping, Reynolds-averaged Navier ? Stokes equations, transonic compressor
Pages: 679-685

Abstract >>
A local damping of eddy viscosity depending on the ratio of the production of turbulent energy to turbulence dissipation rate is proposed at the computation of flows in transonic axial compressors. The results of the numerical modeling of flows in compressor NASA Rotor 37 are presented, and the computed distributions of the increase in the total temperature and total pressure are compared with experimental data for different rotation frequencies. An increase in the accuracy of modelling was obtained in all considered regimes.

Investigation of the high-current arc in helium

A.S. An'shakov, E.K. Urbakh, S.P. Vashchenko, B.A. Pozdnyakov, A.E. Urbakh, V.A. Faleev, V.S. Cherednichenko
Keywords: arc discharge, plasmatorch, electrode erosion, arc current and voltage
Pages: 687-689

Abstract >>
The secondary and erosion characteristics of the electric-arc plasmatorch were studied experimentally. Formulas for arc voltage calculation depending on helium flow rate, diameter of the inner cavity of cylindrical copper anode, arc current, and distance from the nozzle to metal melt were derived.

The properties of carbon-carbonic condensate synthesized in the plasma arc

А.Е. Belikov, А.V. Zaikovsky, V.А. Mal'tsev, О.А. Nerushev, S.А. Novopashin, V.P. Pakharukova, P.V. Snytnikov, C.Z. Sakhapov, D.V. Smovzh
Keywords: arc discharge, anode spraying, carbonic material
Pages: 691-694

Abstract >>
Physical and chemical properties of carbon-carbonic condensate synthesized by the plasma-arc technology have been studied experimentally. X-ray phase analysis has been performed, the isotherms of physical adsorption and sorption ability of the synthesized material have been measured. It has been concluded that this material offers promise as a carrier of catalytic nanoparticles and effective sorbent.

New criterion for comparison of classical theory of nucleation in superheated liquids with experimental data

G.V. Ermakov, E.V. Lipnyagov, S.A. Perminov
Keywords: classical stationary theory of nucleation in the superheated liquids, homogeneous and heterogeneous boiling-up, average lifetime in superheating state, criterion for comparison of empirical lifetimes with the theory
Pages: 695-699

Abstract >>
We have obtained inequality where J is the frequency of homogeneous nucleation, V and are, respectively, volume and average lifetime of the superheated liquid, and is relative statistical error Inequality appears to be a consequence of nucleation homogeneity and stability used at its deduction and taken in the theory as initial and determinant assumption. Calculations with the use of experimental data for the boundaries of the attainable superheating show that inequality is not satisfied. Thus, experimental data can not be considered a proof of the theory fundamentals.