Mathematical modeling of the aerodynamics and physicochemical processes in the freeboard zone of a circulating fluidized bed furnace. 3. Boundary conditions. Some numerical results

Boundary conditions are formulated for differential equations describing two-dimensional motion of gas and polydisperse coke and ash particles in a high-concentration flow [1, 2]. Specific features of the aerodynamics of the pneumatic transport zone in the freeboard zone was investigated numerically in a circulating fluidized bed reactor. The model constructed is verified by experimental data [3].Institute of Problems of Energy Conservation, Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 6, pp. 681–688, June, 1994.     

Mathematical modeling of aerodynamics and physicochemical processes in the freeboard zone of a circulating fluidized bed furnace. 1. Statement of the problem. Basic aerodynamic equations

The authors have obtained a set of equations describing two-dimensional motion of gas and polydisperse char and ash particles in a high-concentration two-phase ascending flow. Interphase interaction, turbulent and pseudoturbulent particle transfer, and effects of the channel walls and mass forces are taken into consideration.Institute of Problems of Energy Conservation, Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 521–526, November, 1993.     

Classification of highly dispersed powders in tray separators

We carried out a numerical simulation of the motion and classification of miron-sized particles in a tray separator with a nontraditional direction of tray concavity.Institute of the Problems of Energy Saving, Academy of Sciences of Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 6, pp. 949–953, November–December, 1996.     

Fractal and information characteristics of the stressed state of a massif and their effect on the process of fracture formation

A probability-information method for describing the stressed state of a massif is developed. An analysis of the interrelationship of massif fracturing, the shape of the tool, and the stressed state of the massif in loading is made, and the dependence between the information characteristics of these distributions is found.Institute of Superhard Materials, Academy of Sciences of the Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 73–77, July–August, 1994.     

Influence of anharmonic effects on the structural-mechanical and thermophysical properties of filled polymer systems

The force constants of anharmonicity, the total energy, and the force of interaction between structural elements of PVC systems are determined from the values of the quasielastic constants of filled polymer systems.Rovno Pedagogical Institute, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 44–50, January–February, 1995.     

Mathematical modeling of convective heat and mass transfer in the drying of solid particles in a bed

A closed system of equations is proposed for calculating convective heat and mass transfer in the drying of solid particles by a gaseous heat transfer agent in a moving bed. As an example, the operation of a belt-type dryer with crossed interaction of a drying agent and a bed of fruit cut into circular slices is considered. Results of a numerical solution of the problem are presented in figures.Institute of Engineering Thermophysics, Academy of Sciences of Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 48–53, July–August, 1994.     

Mathematical modeling of aerodynamics and physicochemical processes in the freeboard region of a circulating fluidized bed furnace. 2. Interaction of particles (pseudoturbulence)

Formulas are obtained for determining the energy generation and dissipation rates of random (turbulent and pseudoturbulent) motion of particles due their collisions and the effect of the aerodynamic drag force. The averaged force of interparticle interaction, pseudoturbulent transfer coefficients for the gas of particles, and other quantities are calculated which are necessary to complete the set of equations describing the aerodynamics of the pneumatic transport zone of a circulating fluidized bed reactor [1].Institute for Power Supply Problems, Kiev, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 2, pp. 159–167, February, 1994.     

Comparative investigation of the heat-transferring ability of heat pipes with lengthwise uniform and variable porous capillary structures

We performed a comprehensive experimental study of low-temperature heat pipes with capillary structures having uniform and variable characteristics over their length. A comparative analysis was made, on the basis of which we formulated an approach to the optimization of a porous capillary structure with lengthwise variable parameters.Institute of Materials Science, Academy of Sciences of the Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 86–92, July–August, 1994.     

Hydrodynamic activity of polymers in high-speed flows

The roles of longitudinal and transverse velocity gradients in the manifestation of distinctive features of polymer solution flows are analyzed.Makeevka Construction Engineering Institute, Donetsk Institute of Commerce, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 146–148, January–February, 1995.     

Operation of thermosyphons at small angles of inclination to the horizontal

Thermosyphons with internal coaxial inserts in the heating zone are investigated. Their operation at small angles of inclination to the horizontal is analyzed. The optimum design of the inserts that ensures operation of the thermosyphons at an angle of inclination of 5° is determined.Institute of Technical Thermophysics, Academy of Sciences of the Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 258–260, September–October, 1994.     

A theoretical and experimental study of the mobility of loose materials

The effect of external and internal parameters of loose materials on their mobility is investigated. A dimensionless equation describing the mobility of loose materials is obtained and confirmed by experimental data.M. V. Lomonosov Technological Institute of the Food Industry, Odessa, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 5–6, pp. 418–423, November–December, 1994.     

Local heat transfer on the entrance segment of a tube with a sharp inlet edge. 1. Nature and behavior of heat transfer intensity extrema

Experimental results on local heat transfer on the entrance segment of a round smooth tube with a sharp leading edge when Re _d =(13–110)·10³, X/d=0.1–13, which support the previously proposed model for separated flow, are examined. It is shown that under separated flow conditions the usual sequence of flow transitions in a boundary layer for mixed nonseparated flows and Re _d >10⁴ is still retained. Formulas are obtained for calculating local heat transfer coefficients on a segment where a laminar boundary layer occurs, including cross sections where these coefficients acquire extreme values.Kiev Polytechnic Institute, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 2, pp. 131–138, August, 1993.     

Dynamics of gas combustion in a spherical vessel

Equations are obtained to describe the dynamics of motion of a flame front and a gas in a spherical vessel. The possibility of a transition from combustion to thermal shock is demonstrated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 42, No. 5, pp. 750–757, May, 1982.     

Heat and mass transfer in a solidfying binary melt under mixed convection with account for turbulence

A generalized mathematical model has been developed for heat transfer and hydrodymanics with account for turbulence in the stages of pouring and subsequent formation of a steel ingot.Donetsk State University, Donetsk, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 202–208, September–October, 1994.     

Nonclassical heat conduction problem for crystal bodies with coatings heated by radiation with account for the curvature of the coating

Generalized conditions for heat transfer of thermosensitive crystal bodies with coatings are formulated that are necessary for determination of their Kirchhoff variables with account for the curvature of the coating.Deceased.Institute of Applied Problems of Mechanics and Mathematics, Academy of Sciences of Ukraine, Lvov, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 5, pp. 622–626, May, 1994.     

Taylor-Görtler laminar instability near a concave surface

On the basis of linear and nonlinear approximations, a more accurate value of the critical Görtler number is found and the effect of Taylor-Görtler vortices on surface friction in the transverse direction is determined.Institute of Technical Thermophysics, Academy of Sciences of the Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhrnal, Vol. 67, Nos. 1–2, pp. 3–9, July–August, 1994.     

Theory of cohesion and break of connections. Report 2. Unification and separation of motions. cohesion. Break of a connection

Operations of unification and separation of motions which are mutually reciprocal are considered. Cohesion is defined as a motion produced as a result of unification of two homeomorphous transformation which set contact between bodies. As a correspondence, coherence is everywhere determinate, surjective, functional, continuous, injective, and reciprocally discontinuous. Break of a connection is defined as a motion produced as a result of unification of two homeomorphous transformations which set the break of contact between bodies. As a correspondence, the break of a connection is everywhere determinate, surjective, injective, inversely continuous, nonfunctional, and discontinuous. In the case when homeomorphous transformations are identical mappings, cohesion and break of a connection coincide with operations of unification and separation of the bodies. The most simple motions (motion of particles) from which all remaining motions are formed [1–4] are determined by means of the operations of unification and separation of motions analogous to the determination of the simplest objects (particles).Translated from Problemy Prochnosti, No. 10, pp. 103–107, October, 1989.     

Interaction of Zr+Nb with carbon,nitrogen, and hydrogen in the combustion mode

Systematic investigations of combustion of heterogeneous systems based on zirconium, niobium, and nonmetals, viz., carbon, nitrogen, and hydrogen, are conducted. The combustion regularities of three-, four-, and five-component systems and the dependences of the combustion temperatures and rates and the chemical composition of the final products on the process parameters are studied. Changes in the gasless and filtration modes of combustion in multicomponent systems are revealed. The basic factor influencing the formation of single-phase multicomponent compounds are ascertained. Concentration triangles are constructed, which are pseudophase diagrams of the Zr–Nb–C system for combustion in argon, nitrogen hydrogen, and a nitrogen-hydrogen mixture that represent the evolution of the phase composition of the combustion products, depending on the reaction medium.Institute of Chemical Physics, Academy of Sciences of the Republic of Armenia, Erevan. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 389–393, October, 1993.     

Generalized percolation theory for the analysis of the structure and properties of porous and composite materials

Expressions are obtained for calculating percolation characteristics of heterogeneous systems with the use of refined auxiliary relations in the entire range of their porosity (concentration of a disperse phase).Institute of Engineering Thermophysics, Academy of Sciences of the Ukraine, Kiev. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 3, pp. 348–352, March, 1994.     

Highly efficient cryogenic thermal insulation for optical devices and pipelines

Experimental results are presented on the improved efficiency of shielding vacuum thermal insulation (SVTI) with gaskets fabricated from polyethyleneterephthalate (PET) film treated with antistatic substances (surface-active substances (SAS)) for reduction of electrostatic charges and contact heat transfer (by 30% or more).B. I. Berkin Physicotechnical Institute of Low Temperatures, Kharkov, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 51–54, January–February, 1995.