Heat transfer in a horizontal coiled pipe in a transient regime and at a near-critical pressure of a fluid

It has been established that in the region of pressures close to a critical one, heat transfer in a transient regime of motion of a single-phase flow in a horizontal coil pipe changes nonuniformly over the cross section of the perimeter. The main factors here are the influence of inertia forces and of free convection. Equations to calculate the heat-transfer coefficient are suggested. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 892–896, September–October, 2008.     

Experimental study of flow structure and heat transfer under a jet flow past a spherical-cavity obstacle

The results of an experimental study of the aerodynamic characteristics and heat transfer under a jet flow past a spherical-cavity obstacle are presented. It has been revealed that in a spherical cavity the flow becomes nonstationary and is characterized by low-frequency oscillations of local values of the heat flow density. The heat transfer intensity in a hollow is lower than on a flat obstacle, and in the region of depression this decrease is practically completely compensated by an increase in the heat-transfer surface area. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 29–37, July–August, 2006.     

Analytical methods of investigation of the thermal state of a region with a moving boundary under the conditions of nonstationary heat transfer to the external medium

An analytical method of solution of combined problems of nonstationary heat conduction for a region with a boundary moving according to a known law and with a time-variable coefficient of heat transfer is developed. The idea of splitting the kernel of the obtained generalization of a singular integral Fourier transform with respect to a space variable provides a basis for the method. Theoretical results are used in mathematical simulation of heat transfer processes in the region with a moving boundary under the conditions of nonstationary heat transfer to the external medium. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 125–130, January–February, 2000.     

Unsteady wave flows of a gas suspension with account for phase changes

A system of equations of unsteady motion of a gas suspension with account for heat and mass transfer is presented. As a result of the computational experiment, the effect of the gas vibrations at the channel inlet on the motion of the gas suspension and the rate of heat and mass transfer is studied. Specifically, it is shown that, in the considered parametric region, the gas vibrations enhance the interphase heat and mass transfer. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 3, pp. 487–492, May–June, 2000.     

Simulation of the supersonic turbulent flow around a cylinder with coaxial disks

The turbulent axisymmetric flow around a stepped body — a cylinder with coaxial front and rear disks — has been calculated with the aid of a VP2/3 package based on multiblock computational technologies and the generalized procedure of pressure correction. The computational model has been tested with the example of a supersonic flow around a sphere. The numerical forecasts made with the use of Spalart–Allmares shear stress transfer and eddy viscosity transfer models have been compared with the data of the aeroballistic experiment, wind tunnel tests, and the results of the calculation of the flow around the disk–cylinder arrangement by a simplified zonal model in a wide range of variation of the incident flow Mach number (from 1.5 to 4). We have obtained a good agreement between the calculated transverse flow density distributions in the front stalling zone and those determined from the interferograms for the wave-drag-rational disk–cylinder arrangement. The influence of the rear disk on the drag of the disk–cylinder–disk arrangement has been estimated.     

A class of integral transformations for the generalized equation of nonstationary heat conduction

Integral transformations for finding analytical solutions of the boundary-value problems of nonstationary heat conduction for the generalized equation of transfer in an infinite region bounded on the inside by a plane, cylindrical, or spherical surface have been constructed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 123–130, January–February, 2008.     

Mathematical simulation of conjugate heat exchange in heating furnaces with a moving bottom

A mathematical model of conjugate heat exchange in heating furnaces with a moving bottom (ring furnaces and walking-beam furnaces) has been developed. The model allows one to determine the heating of steel blanks in these furnaces with account for all mechanisms of heat transfer in the high-temperature working region of a furnace, in its lining, and in the steel blanks. On the basis of this model, a more economical regime of operation, as compared to the existing ones, has been calculated for a walking-beam furnace and comparative analysis of the operating characteristics of a ring furnace and a walking-beam furnace has been performed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 3–11, May–June, 2006.     

Use of equations for transfer of particle pulsation characteristics for calculating two-phase flows in the stabilized section of a tube

A stationary isothermal system of equations defining the behavior of a two-phase rising flow in the region of steady motion of a gas suspension in an axially symmetric channel has been developed. The equation of motion of the carrying medium is closed using a one-parameter model of turbulence, and the equation of momentum transfer in the dispersed phase is closed with the use of the equations for the second, third, and fourth moments of the pulsation velocities of the particles. The main mechanisms of two-phase turbulent flows were numerically investigated. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 99–109, July–August, 2007.     

Conjugate heat transfer in a closed domain with a locally lumped heat-release source

Free convective heat transfer in a solution domain quite accurately modeling the cross section of the object of heat consumption has been investigated numerically. Typical velocity and temperature fields have been presented. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 56–63, January–February, 2006.     

Electric-field strength in a cascade argon arc

An experimental investigation of the electric-field strength along the length of a cascade argon at a pressure lower than atmospheric pressure has been performed. The influence of different processes on the formation of the voltage-current and E-I characteristics of the arc was considered. It is shown that the processes of heat transfer are of primary importance; however, in the region of mixing of the cathode jet with the heated gas the Reynolds number has a marked influence. The generalized characteristics of the voltage across the arc, of the near-electrode voltage drop, and of the electric field strength averaged over the length are presented. Deceased Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 5, pp. 973–978, September–October, 2000.     

Heat and mass transfer in the destruction of thermal protective materials with a different content of a polymer binder in a high-enthalpy gas flow

With the aid of a complex experimental procedure, we consider the mechanism of thermal destruction of carbon-phenol thermal protective compositions with a different content of components in the interaction with a high-enthalpy gas flow. Thermophysical, thermokinetic, and structural properties of the thermal protective compositions are determined. The effect of the rate of heating on characteristics of the transfer coefficients, which is specified by a kinetic shift of the pyrolysis reactions to a high-temperature region, is ascertained. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 61–66, January–February, 2000.     

One-velocity model of a multicomponent heat-conducting medium

A model of a one-velocity heat-conducting heterogeneous medium with the Fourier relaxation law of heat transfer has been constructed. It is shown that the model’s equations are of hyperbolic type. The results of numerical experiments for a three-component mixture of ideal gases carried out with the use of the Courant–Isaacson–Rees scheme are presented.     

Investigation of regimes of thermogravitational convection of a fluid between coaxial semicylinders with a heat-conducting shell in the presence of a local energy source

A numerical analysis has been made of the thermodynamic regimes of natural convection of a Newtonian fluid satisfying the Boussinesq approximation in the gap between coaxial semicylinders with finitely-thick walls in the presence of the heat-release source under the conditions of convective heat exchange with the environment. A mathematical model has been formulated in the dimensionless variables current function–velocity vorticity vector–temperature in polar coordinates. Streamlines and velocity and temperature fields reflecting the influence of the Prandtl number Pr = 0.7 and 7.0, the nonstationarity factor 0 < τ ≤ 300, the dimensions of the energy source, and of the relative thermal conductivity on the flow regimes and heat transfer have been obtained.     

Two-dimensional convective diffusion of a radioactive impurity with allowance for sorption in a porous medium

A mathematical model of the two-dimensional convective diffusion of radionuclide transfer in a porous medium has been considered. A fundamental solution in the form of Green's function has been obtained for this model. The analytical expressions of the impurity-concentration distribution for stationary conditions and for a few kinds of boundary conditions have been given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 417–420, May–June, 2008.     

Statement of boundary and conjugation conditions for problems of heat transfer in granular beds on the basis of a two-temperature model

Physically justified boundary and conjugation conditions for problems of heat transfer in infiltrated granular beds have been formulated within the framework of the two-temperature model that takes into account the absence of interphase interaction at the boundaries. It is shown that the classical Danckwerts conditions are applicable to a gas. The problem of filtration cooling of a heat-generating granular bed over which there is an inert bed (pile-up) has been solved in a new statement. The dependence of the pressure drop in a granular bed on the mass flow rate of the gas is established. A formula to calculate the maximum temperature of particles is obtained. The region of applicability of the one-temperature model is determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 6, pp. 98–106, November–December, 2006.     

Conduction mechanism in doped polymethyl methacrylate (PMMA) films

The electrical transport behaviour of ferrocene mixed poly (methyl methacrylate) (PMMA) films (≈ 20 μm in thickness) deposited by the isothermal immersion technique has been studied in the temperature range of 333–373 K and field from (2·0–4·0)×10⁴ V/cm. It has been found that at higher fields and temperatures, the observed conduction behaviour could be consistently described by the Richardson-Schottky emission. The increase in current due to doping has been attributed to the formation of charge transfer complexes. The dopant molecules act as an additional trapping centre and provide a link between polymer molecules in amorphous region leading to the formation of charge transfer complex.     

Mass transfer in a jet device

The process of mass transfer in a jet device has been investigated by the evaporation of water. Methods of calculating the interface formed by gas bubbles and measuring the mass-transfer coefficient have been developed. The experimental and calculated mass-transfer coefficients have been compared. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 6, pp. 84–88, November–December, 2005.     

Comparative analysis of the integral and field methods of calculating the heat and mass transfer in a fire within a building

Integral and field models of calculating the heat and mass transfer in a fire within a building have been considered. The parameters of a model fire within a building, calculated by the methods proposed, were compared. The range of reliable use of the integral model has been determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 2, pp. 99–108, March–April, 2006.     

Nonstationary radiation-gasdynamic model of a laser-plasma accelerator

Based on the system of two-dimensional axisymmetrical continuity equations, Navier-Stokes and energy equations, and the equations of selective heat radiation transfer, a computational model is constructed and conditions of unsteady subsonic flows in a cylindrical channel of a power unit of the laser-plasma accelerator type are investigated. The governing parameters of the model are calculated, at which numerical solutions can be obtained to describe steady laminar gas flow in the neighborhood of the region of heat release, nonstationary oscillatory motions, and nonstationary vortex motion. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 1, pp. 174–179, January–February, 2000.