Effect of eddy formation on gas mixture homogeneity near a substrate in a vertical reactor for CdHgTe deposition

This paper presents simulation results obtained for an unsteady-state flow of a multicomponent gas mixture in a flow-type vertical reactor using a three-dimensional mathematical model that takes into account the convective mass and heat transport, compressibility, viscosity, and thermal conductivity of the components and gas flow turbulization. We identify the gas dynamic mechanism behind eddy formation in the reactor and examine the influence of the viscosity, density, and speed of the flow components on eddy formation and the homogeneity of the gas mixture over the substrate.     

Two-Fluid Hydrodynamic Model of Bubble Flow

A computational model of unsteady-state two-fluid flow is proposed on the basis of a set of momentum and continuity equations, which corresponds to one-dimensional flow of a gas–liquid mixture with barotropic components. The model takes into account the Zuber–Findlay relation [1] and includes solutions to the Cauchy problem that are close to the solutions to the drift model. The associated-mass effect on solutions to the characteristic equation corresponding to this model is investigated. It is shown that the associated-mass effect has a pronounced impact on the acoustic characteristics of the set of equations.     

Simulation of unsteady-state hydrodynamics under conditions of turbulent flow in pipes

Modern approaches to simulation of turbulent flows are used to analyze the effect of nonstationarity of the flow rate on the parameters of turbulence. The flow rate variation in the case of homogeneous turbulence with constant shear of velocity is treated. The dynamics of the second moments of velocity fluctuations at constant flow rate are investigated. Calculations of unsteady-state pipe flow are performed within the two-parameter model of turbulence. Qualitative comparison is made of the theoretical and experimental results.__________Translated from Teplofizika Vysokikh Temperatur, Vol. 43, No. 2, 2005, pp. 231–248.Original Russian Text Copyright © 2005 by I. V. Derevich.     

Numerical simulation of the spatial structure of a moving arc discharge

Results are given of the calculation of the structure of an arc discharge moving on parallel electrodes in air under the effect of a transverse magnetic field (0.086 T) at a current strength of 320 A. The numerical simulation is performed within an unsteady-state three-dimensional mathematical model of radiation magnetogasdynamics. The calculations reveal that fluctuations of values of physical parameters and of spatial shape of arc arise in the arc, which are caused by the gas flow past the discharge column and by unsteady-state processes in the electrode regions. Comparison is made with the available experimental data.     

Modeling of vortex structures on the lateral surface of a cylinder in a longitudinal flow

The problem of generation of vortex structures by ejection of a jet through an annular slot on a cylindrical surface in a longitudinal flow is considered. Results of modeling of large-scale vortices and their effect on local characteristics of the wall boundary layer are presented. The modeling is based on numerical integration of the Navier-Stokes equations in an axisymmetric formulation. An unsteady-state flow with separation and entrainment of vortices by the main stream is obtained. The decrease in the friction drag achievable in devices of this kind is estimated.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 5, pp. 527–533, May, 1994.     

Determination of unsteady-state temperature fields in multilayered orthotopic plates

A new hypothesis on temperature distribution with respect to the thickness of a multilayered plate is proposed. An analytical solution of the unsteady-state heat conduction problem is obtained for rectangular multilayered orthotropic plates.Kiev Motor-Car and Road Institute, Ukraine. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 4, pp. 486–491, October, 1992.     

Self-similar solutions in the problem of diffusion of a vortex in a temperature field

The author considers self-similar solutions of a system of, nonlinear equations describing unsteady-state diffusion of a vortex with a heat source inside it with power dependences of the viscosity and the thermal conductivity on the temperature being included in the solution. Functions having a reasonable physical interpretation are singled out from the set of possible solutions.All-Russian Research Institute of Transport Machine Building St. Petersburg, Russia., Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 219–227. September–October, 1994.     

Theory of gaslifts

On the basis of a simplified model, a new method is proposed for the analysis of unsteady-state gaslifts, and instabilities of steady-state gaslift processes are demonstrated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 4, pp. 561–569, October, 1987.     

Study of several reactor construction designs in application to the process of oil pyrolysis in a plasma jet

The possibility of plasma jet pyrolysis of oil in a direct flow reactor and a reactor with a reverse flow design was confirmed experimentally. A comparison was made of the technological output of gaseous products for different system parameters for both construction variants.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 3, pp. 462–466, March, 1971.     

Numerical Simulation of Self-Excited Oscillation of a Turbulent Jet Flowing into a Rectangular Cavity

The example of a plane jet flow into a rectangular cavity (“dead end”) is used in comparing the capabilities of different approaches to numerical simulation of self-oscillatory turbulent flows characterized by global quasi-periodic oscillation of all flow parameters. The calculations are performed for two flow modes, of which the first one is statistically steady according to the available experimental data, and the second one is self-oscillatory. In both cases, three approaches are used to describe the turbulence, namely, the method of large eddy simulation (LES) in combination with the subgrid model of Smagorinsky, and steady and unsteady Reynolds averaged Navier-Stokes equations (SRANS and URANS) with two well-known differential models of turbulence. In the case of the first flow mode, all three approaches produce qualitatively similar and quantitatively close results. In the case of the second (self-oscillatory) mode, a steady-state solution of Reynolds equations may only be obtained in half the domain using the symmetry boundary conditions; within the framework of the other two approaches, the solutions turn out to be unsteady-state. In so doing, their characteristics calculated using the LES and URANS methods differ significantly from each other; in the case of URANS, they further depend on the model of turbulence employed. The best results as regards the accuracy of prediction of the amplitude-frequency characteristics of self-oscillation are produced by the use of the LES and three-dimensional URANS methods. A similar inference may be made with respect to the mean flow parameters. From this standpoint, the worst results are those obtained from calculations involving the use of the symmetry boundary conditions on the geometric symmetry plane of the flow.__________Translated from Teplofizika Vysokikh Temperatur, Vol. 43, No. 4, 2005, pp. 568–579.Original Russian Text Copyright © 2005 by D. M. Denisikhina, I. A. Bassina, D. A. Nikulin, and M. Kh. Strelets.     

Automated fault tree synthesis by semantic network modeling, rulebased development and recursive 3-value procedure

A concept of flow is introduced to represent any material, information, energy, activity, or phenomenon which can move or propagate along flow paths to cause events specific to the system to be analyzed. A graphical equipment library is given to represent typical types of ‘generation rate’ and ‘aperture’ controllers. The system is modeled by a semantic network with labeled arrows showing effect to cause (backward) relationships between flow and equipment nodes. A correspondence between the equipment library and the system components is established, and the semantic network is constructed by integrating network fragments in the library. Fixed and/or free boundary conditions can be specified explicitly for flow or equipment nodes. Forward-chaining event development rules locally trace the labeled arrows, while a 3-value procedure guides the FT generation by recursive rule applications. The rules are obtained from tables and equipment definitions. The 3-value logic is used to truncate FTs according to the boundary conditions. Different FTs are generated for different top events and boundary conditions, given a semantic network model. FT modules and their hierarchies can be identified by examining network theoretic properties of flow nodes. The proposed approach is demonstrated for a relay system, a hypothetical swimming pool reactor and a chemical reactor.     

Propagation of disturbances of pressure in a porous medium under conditions of filtration of a two-phase flow

The paper deals with the results of experimental investigation of unsteady-state processes in a channel with a porous medium under conditions of filtration of liquid-vapor flow and pressure disturbances initiated by injection of steam or noncondensing gases from an outside source. Singular features are studied of the propagation of pressure waves in a porous medium compared to dynamic processes occurring in an unfilled round pipe. The experimentally measured values of the propagation velocity of low-amplitude pressure waves in a channel with a pebble bed correspond to the calculated values of the equilibrium sound velocity of a liquid-vapor medium. It is for the first time that this result is obtained.Translated from Teplofizika Vysokikh Temperatur, Vol. 42, No. 6, 2004, pp. 947–953.Original Russian Text Copyright © 2004 by B. G. Pokusaev, E. G. Tairov, and M. Yu. Gritsenko.     

The Effect of Hydrodynamic Unsteadiness on the Flow Structure and on the Coefficients of Heat Transfer and Skin Friction under Conditions of Turbulent Pipe Flow of Heat-Transfer Agent

Critical analysis is made of the current status of investigations of heat transfer and skin friction under conditions of unsteady-state turbulent pipe flow. This analysis is based on the experimental data on the structure of turbulent flows and heat transfer. Comparison is made of experimental and theoretical results.     

The Bifurcation of Subsonic Gas Flow past a Localized Volume of Low-Temperature Plasma

The results are given of numerical investigation of the gasdynamic structure of heat-conducting subsonic flows past volumes of low-temperature plasma localized in space. Cases of intense heat release in atmospheric air are investigated, with the gas being heated to 10000–20000 K so that the local density differences reach tens and hundreds of times. Various modes of gas motion are revealed and investigated, such as steady-state laminar flow past the low-temperature plasma region with partial percolation and unsteady-state oscillating flow modes without and with formation of regions of return motion.     

Pulsational characteristics of the model of mass flow in a flow-through reactor

Liquid flow in a flow-through reactor and one-dimensional longitudinal turbulent mass transfer is considered. The turbulent mass flux is described by a second-order differential equation including the velocity and spatial scale of the turbulent pulsations. Conditions of pulsed tracer introduction in the reactor are considered, and the inverse problem for experimental determination of the pulsational characteristics is solved by the moment method.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 60, No. 1, pp. 73–76, January, 1991.     

Distinctive features of the model of the drift of phases used in computational dynamic reactor programs

We present relations of the overall model of drift for use in dynamic reactor programs. On the boundaries that separate the sets of conditions of a two-phase flow, a smooth transition is achieved between the drift velocity relations corresponding to different regimes. The relations suggested can be use for vertical channels of various geometries with ascending and descending motion of a coolant in a wide, range of flow velocities.Scientific-Research Technological Institute, Sosnovyi Bor. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 3–4, pp. 209–218, September–October, 1994.     

Ultrafiltration in a pipe filter with gelation

We investigate the process of unsteady-state ultrafiltration with gelation under laminar flow conditions in a pipe filter with nonideal selectivity of its membrane. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 71, No. 3, pp. 503–508, May–June, 1998.     

Error minimization in nonlinear variational unsteady-state heat conduction problems

The article considers a variational method of solving unsteady-state heat conduction problems.Belarussian State Polytechnical Academy, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 3, pp. 341–349, September, 1993.     

Strength characterization of MgO-partially stabilized zirconia

The flexural strength of MgO-partially stabilized zirconia was evaluated as a function of temperature (20–1300 °C in air environment), applied stress and time. The indentation-induced-flaw technique did not produce well-defined symmetrical cracks of controlled size, whose length (on the tensile surface) or depth (on the fracture face) can be measured unambiguously, and therefore it should not be used for measuring fracture toughness. The sudden decrease in fracture strength at moderately low temperatures (200–800 °C) is believed to be due to stability of the tetragonal phase and relative decrease in the extent of the stress-induced martensitic phase transformation of the tetragonal to monoclinic phase. Flexural stress rupture testing at 500–800 °C in air indicated the material's susceptibility to time-dependent failure, and outlines safe applied stress levels for a given temperature. Stress rupture testing at 1000 °C and above at low applied stress levels showed bending of specimens, indicating the onset of plasticity or viscous flow of the glassy phase and consequent degradation of material strength.     

Mathematical simulation of electromagnetic stirring of liquid steel in a DC arc furnace

Results are given of numerical simulation of electromagnetic stirring of metal melt in a dc arc furnace. The flow pattern and the transport of passive admixture in baths with one and two electrodes are studied. The mathematical model describes three-dimensional turbulent flow of electrically conducting liquid in the field of gravitational and electromagnetic forces. The parameters of turbulence are calculated in two approximations, namely, unsteady-state approximation by the large eddy simulation (LES) model and quasisteady-state approximation by the k-ε model.