Nonstationary flow of solutions of flexible-chain polymers in a porous medium

Aqueous solutions of polyethylene oxide have been studied under the conditions of nonstationary longitudinal flow. The investigations have confirmed the deviations from Darcy’s law according to the mechanism the basis for which is provided by the concepts of a strong strain action of the hydrodynamic field on coiled macromolecules. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 5, pp. 123–127, September–October, 2005.     

Determination of the molecular characteristics of polyolefins with the use of the Toms effect

The interrelation between the physicochemical properties of macromolecules and the hydrodynamic parameters of a turbulent flow of diluted polymer solutions in a cylindrical channel has been analytically determined. The possibility of estimating of the molecular characteristics of high-molecular polymers with the use of the turborheometric method has been considered. The antiturbulence efficiency of polyhexane used in energy-conserving technologies of pipeline transport of hydrocarbon materials has been analyzed on the basis of comparison of the molecular masses of polymers determined by different methods. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 1, pp. 162-166, January–February, 2006.     

Determination of the optimum conditions for synthesis of a diene rubber based on a neodymium-containing catalytic system with definite branching characteristics

A mathematical simulation of the concurrent processes of heat exchange and chemical transformation in the synthesis of a diene rubber based on a neodymium-containing catalytic system (CDNR) in a cascade of continuous reactors has been carried out. A model is proposed for investigating the branching of the CDNR. The problem of optimization of the polymerization of a butadiene rubber based on a neodymium-containing catalyst was solved for the case of an increasing number of reactors in a cascade. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 2, pp. 153–160, March–April, 2007.     

Development of Certain Aspects of the A. V. Luikov Heat- and Mass-Transfer Theory

It has been proposed that A. V. Luikov's system of heat- and mass-transfer equations be supplemented with balance differential equations of change in the temperature and degree of saturation of a medium with its motion in the material for an a priori unknown character of their change. The approach to determination of the relative coefficient of thermal diffusion, the criterion of phase transition, and the value of the Fo number for the beginning of the stage of a regular regime of a one- and two-dimensional plate and to evaluation of the notion of the “soft” and “hard” processes of drying has been refined. The method of allowance for the multidimensionality of a body has been developed. The practical absence of the influence of moisture exchange on heat exchange in drying has been proved. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 4, pp. 102–107, July–August, 2005.     

Thermally thin system for investigating surface diffusion flames

A thermally thin layered system representing a liquid fuel on a metal substrate was investigated. The characteristic parameters of such a system are the thickness of the fuel layer and the thickness of the substrate, equal to 3–12 and 10–100 μm respectively. Hydrocarbons were used as a fuel. It has been established that in this system a number of stationary and nonstationary combustion regimes with conductive and convective mechanisms of chemical-reaction transfer and non-one-dimensional combustion waves with an unusual structure and an "excess of energy" can take place.     

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.     

Liquid chromatography of macromolecules at the point of exclusion–adsorption transition

Liquid chromatography of macromolecules at the point of exclusion–adsorption transition (LC PEAT) is based on a controlled balance between entropic (exclusion) and enthalpic (adsorption) effects within LC system that results in the loss of separation according to the molar mass. Consequently, polymer species exhibiting the same adsorptivity but different sizes are eluted in one single retention volume that roughly corresponds to the total volume of liquid within column. At the same time, other kinds of polymer chains with different adsorptivities are eluted according to either exclusion or adsorption mechanism. This may allow discrimination and independent characterization of chemically different species such as functionalized macromolecules, block- and graft- copolymers and polymer blends. Differences in the physical structure of macromolecules, for example in their stereoregularity represent an alternative separation parameter. Four approaches to the exclusion–adsorption transition in liquid chromatography of macromolecules were so far proposed, viz. liquid chromatography at the critical adsorption point (LC CAP), liquid chromatography at the theta exclusion-adsorption conditions (LC TEA), liquid chromatography under limiting conditions of adsorption (LC LCA) and liquid chromatography under limiting conditions of desorption (LC LCD). The principles of LC CAP, LC TEA, LC LCA and LC LCD and their applicability are elucidated and the advantages and problems of particular methods are discussed in the present review. Received: 9 October 2000 / Reviewed and accepted: 10 October 2000     

Chain model of generation of heat in a solid dispersion of subdomain ferroparticles on exposure to a variable field

The release of heat in a system of small ferromagnetic particles with magnetic hysteresis on exposure to a variable linearly polarized field has been studied. A chain model of the noncoherent process of magnetization reversal has been proposed; compared to the theory of absolute single-domainality, the model made it possible to bring computational results closer to experimental data. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 131–136, January–February, 2008.     

Analytical solution of the problem on thermal slip of second order for molecular gases

Results obtained using exact analytical methods in the problem on thermal slip of second order for molecular gases with allowance for the rotational degrees of freedom of molecules have been presented. Numerical calculations of the thermal-slip coefficient for a number of molecular gases have been carried out. The dependence of the velocity of thermal slip of second order of a molecular gas on the Prandtl number has been shown. The found value of the coefficient of thermal slip of second order theoretically confirms the existence of negative (in the direction of the temperature gradient) thermophoresis for molecular gases. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 190–194, May–June, 2006.     

Influence of granulated blast furnace slag on the reaction,structure and properties of fly ash based geopolymer

Ground granulated blast furnace slag (GBFS) has been used to alter the geopolymerisation behaviour of fly ash. The influence of varying amount of GBFS (5–50%) on the reaction kinetics has been studied using isothermal conduction calorimetry. It was observed that the reaction at 27 °C is dominated by the GBFS activation, whereas the reaction at 60 °C is due to combined interaction of fly ash and GBFS. The reaction product of geopolymerisation has been characterised using X-ray diffraction and scanning electron microscopy–X-ray microanalysis. Alumino–silicate–hydrate (A–S–H) and calcium–silicate–hydrate (C–S–H) gels with varying Si/Al and Ca/Si ratio are found to be the main reaction products. Coexistence of A–S–H and C–S–H gel further indicates the interaction of fly ash and GBFS during geopolymerisation. Attempt has been made to relate the microstructure with the properties of the geopolymers.     

Modeling of the sorption deformation of glassy polymer sorbents in interaction with gases in a high-pressure region

Based on the phenomenological-thermodynamics method, a model of sorption deformation of a glassy polymer sorbent — polycarbonate — in interaction with carbon dioxide in a high-pressure region has been proposed. The possibility of describing sorption equilibrium for this system has been analyzed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 175–179, September–October, 2006.     

Thermal and force loads on the vehicle surface in high-velocity motion in the earth’s atmosphere

Consideration has been given to a number of aspects of mathematical modeling of a high-velocity flight in the earth’s atmosphere in a wide range of variation of the determining parameters. Super-and hypersonic gas flow past flying vehicles has been investigated based on computer-aided calculations with allowance for its actual properties. Data on the distribution of gasdynamic parameters in the flow field, including thermal and force loads on the surface, have been obtained and analyzed. The issues of applying today’s information technologies to archiving scientific knowledge obtained in electronic databases of a specialized Internet center and their dissemination via the Global Network have been discussed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 2, pp. 338–344, March–April, 2008.     

Modeling of the process of drying of a dispersed material by a superheated steam in a pneumatic-transport system

Mathematical modeling of the cyclic drying of a dispersed material moving in the ascending and descending flows of a superheated steam has been performed. The dependence of the moisture content of particles on the operating parameters of a pneumatic-transport system has been established. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 4, pp. 147–155, July–August, 2007.     

Testing of numerical methods,convective schemes,algorithms for approximation of flows,and grid structures by the example of a supersonic flow in a step-shaped channel with the use of the CFX and fluent packages

An unsteady supersonic flow of a nonviscous gas with a Mach number M = 3 in a step-shaped channel has been calculated. The accuracy of the forecasts made has been analyzed on the basis of the Roe dissipation model and the advective upwind splitting method with the use of convective schemes of the second and third orders of accuracy and algorithms for approximation of flows. Triangular and polyhedral grids have been tested. The mechanism of formation of an artificial physical instability on grid structures with a local-gradient adaptation has been considered. It is shown that the existence of a singular point — a right corner — in the computational region causes a large phase change in the evolution of the flow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 2, pp. 326–330, March–April, 2009.     

Magnetophoretic Properties of a Volume-Ordered System of Rectangular Ferrocylinders

The magnetophoretic properties of a system of identical unidirectional rectangular ferromagnetic cylinders of infinite length have been considered. The influence of the geometric parameters of the system on the distribution of magnetophoretic potential and the characteristic time of isolation of dia- and paramagnetic particles has been studied. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 3, pp. 44–50, May–June, 2005.     

Gravity Effect on the Axisymmetric Drop Spreading

The flattening (spreading) of the axisymmetrical drop on a plane horizontal surface under action of gravity force at zero tangential force (no shear at the gas–liquid interface) is investigated analytically and numerically. We determine the exact profile of compressed drop assuming the condition of drop volume conservation. 2D time dependant numerical model, based on a finite difference method, has been developed to describe the hydrodynamics inside the drop. The energy and Navier–Stokes equations are solved within the drop’s analytical profile. Effects of surface tension and thermocapillarity are taken into account. The effect of gravity has been studied to define main features of the drop dynamics. In calculations vector of gravitational acceleration is oriented perpendicularly to the surface, the Bond number is changed in the range from Bo = 0 to Bo = 151.6. Our results show that the gravity has a significant effect on the drop spreading.     

Equipment for the Spectral Characterization of High-Temperature Particles

The spectral radiant characteristics of plume particles of a solid rocket engine are important in the design of the engine specific impulse, ablative material, and plume flame hiding. These parameters are measured from tests of the engine. Some equipment has been established to realize particle heating, uniform particle distribution, and measurements based on an FTIR spectral instrument. The equipment is based on SiC heating and is divided into a warm-up chamber and a measurement chamber to improve the particle temperature stability. A special design of uniform particle distribution combined with an acoustic levitation device is used to determine the particle falling speed. The spectral characteristics and the transmission rate of the particles have been measured by using the system including a standard blackbody, an assembled optical system, and an FTIR spectrometer. The measurements of particle concentration and temperature are given in detail. The instrument specifications are as follows: temperature range – 60–1500 °C; spectral range – 0.60–25 μm; and particle dimension range – 10–500 μm. Paper presented at the Seventh International Workshop on Subsecond Thermophysics, October 6–8, 2004, Orléans, France.     

Influence of arsenic, antimony and phosphorous on the microstructure and corrosion behavior of brasses

The effect of minor additions of As, Sb and P on phase distribution and corrosion behavior has been studied in brasses. The alloys investigated were 60Cu–39Zn–1Pb, 48.95Cu–45Zn–5Pb–1Sn–0.05As, 48.90Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb and 48.85Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb–0.05P. Immersion tests in 1% CuCl₂ solution indicated that the addition of As improved corrosion resistance while the combined addition of As + Sb and As + Sb + P was not beneficial. The hardness increased significantly with the addition of As, Sb and P. Microstructural observations indicated an increase in β phase fraction in the As, Sb and P containing alloys. X-ray diffraction studies confirmed the formation of intermetallic compounds in As, Sb and P containing alloys. Based on the microstructural observations, the intermetallic compounds appear to be primarily precipitated in the β phase with As + Sb and As + Sb + P additions. The lower corrosion resistance of the alloys 48.90Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb and 48.85Cu–45Zn–5Pb–1Sn–0.05As–0.05Sb–0.05P has been related to increase in β phase volume fraction and precipitation of intermetallic compounds in the β phase.     

Thermoactive coating as a means for controlled action on the temperature field of an infinite solid body with a spherical heating source

A mathematical model of the process of formation of a temperature field in an infinite isotropic solid body containing a spherical heating source with a thermally thin thermoactive coating of its surface has been proposed. The obtained analytical solution of the corresponding problem of nonstationary heat conduction has been used for substantiation of the possibility of acting on the temperature field of the system under study in a controlled manner. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 12–19, May–June, 2006.