scholarly journals The study of the velocity of dispersed particles at different angles of division of a two-phase flow

2019 ◽  
pp. 78-86
Author(s):  
S.A. Shevchenko ◽  
A.F. Shevchenko ◽  
A.P. Tolstopyat ◽  
L.A. Fleyer ◽  
V.I Yeliseyev
Keyword(s):  
Cast Iron ◽  
Flow Separation ◽  
The Other ◽  
Spherical Particles ◽  
Single Particles ◽  
Two Phase ◽  
Injection Process ◽  
Dispersed Particles ◽  
Outflow Velocity ◽  
Air Stream

The aim of this work is to assess the influence of a t-shaped divider (α = 180°) on the speed of movement of spherical particles along the path of a two-nozzle lance in the air stream. Also, comparison with the results of flow separation experiments at smaller angles. The performed studies showed that in the t-shaped divider the reagent particles have a complex trajectory of motion. Part of the particles has an outflow velocity corresponding to other types of divider (7 – 14 m/sec), and the other equilibrium part of the particles is slowed down and has an outflow speed 4 – 5 times lower (1 – 3 m/sec). This is reflected by the bimodal nature of the distribution of the results. In this regard, the transition from single particles to a denser flow (in the case of an increase in the reagent supply intensity) will lead to instability of the injection process, to pulsations and even blocking of the lance. This under conditions of flow into the melt will lead to blockage of the nozzle. This is confirmed by individual attempts to inject granular magnesium through a t-shaped lance in cast iron desulfurization plants. In this case, magnesium was introduced with overestimated flow rates of the transporting gas and an intensity of no more than 5–6 kg/min, which is 5 times less than through a y-shaped two-nozzle lance. In addition, the injection was carried out through one nozzle, since the other in the first seconds of the release of magnesium was clogged. The process proceeded violently and was accompanied by splashes of cast iron from the ladle. It is established that, in comparison with the flow separation angles ( = 30, 60, 90), the t-shaped divider ( = 180) reduces the speed of magnesium and polystyrene particles to a greater extent (by 20 – 50%). In addition, the physical characteristics of the interacting materials, the shape of the particles, the flow rate of the transporting gas, and the length of the nozzle after the divider significantly affect the speed of movement of a solid particle along the path of a two-nozzle lance.

Morphology and Mechanical Properties of Injectable Ceramic Microspheres

2008 ◽  
Vol 396-398 ◽  
pp. 691-694 ◽  
Author(s):  
S.M. Oliveira ◽  
C.C. Barrias ◽  
C.C. Ribeiro ◽  
I.F. Almeida ◽  
M.F. Bahia ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Morphological Structure ◽  
Optical Microscope ◽  
Spherical Particles ◽  
Sintering Process ◽  
Ionotropic Gelation ◽  
Texture Analyzer ◽  
Injection Process ◽  
Air Stream ◽  
Sintering Conditions

The aim of this study was to analyze the effect of starting powder granulometry and sintering conditions on the morphological structure and mechanical properties of injectable hydroxyapaptite (HAp) microspheres. The mechanical properties of the microspheres were evaluated, to investigate if their integrity could be maintained during the injection process. To obtain microspheres, HAp powders were dispersed in a sodium alginate solution and spherical particles were prepared by droplet extrusion under a co-axial air stream, coupled with ionotropic gelation in the presence of Ca2+. This was followed by a sintering process at various temperatures and times. The morphology of microspheres was observed under SEM, diameter measurements were performed in an optical microscope and the compression strength was evaluated using a texture analyzer. Finally, microspheres prepared using lower granulometry HAp powders and sintered at 1200 °C for 1 hour presented the best properties and were selected as the most suitable for the envisaged application.

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

A Ternary, Two-Phase, Mathematical Model of Oil Recovery With Surfactant Systems

1984 ◽  
Vol 24 (06) ◽  
pp. 606-616 ◽  
Author(s):  
Charles P. Thomas ◽  
Paul D. Fleming ◽  
William K. Winter
Keyword(s):  
Mathematical Model ◽  
Oil Recovery ◽  
Arbitrary Number ◽  
The Other ◽  
Phase System ◽  
Chemical Flooding ◽  
Two Phase ◽  
Oil Displacement ◽  
Surfactant Systems ◽  
And Diffusion

Abstract A mathematical model describing one-dimensional (1D), isothermal flow of a ternary, two-phase surfactant system in isotropic porous media is presented along with numerical solutions of special cases. These solutions exhibit oil recovery profiles similar to those observed in laboratory tests of oil displacement by surfactant systems in cores. The model includes the effects of surfactant transfer between aqueous and hydrocarbon phases and both reversible and irreversible surfactant adsorption by the porous medium. The effects of capillary pressure and diffusion are ignored, however. The model is based on relative permeability concepts and employs a family of relative permeability curves that incorporate the effects of surfactant concentration on interfacial tension (IFT), the viscosity of the phases, and the volumetric flow rate. A numerical procedure was developed that results in two finite difference equations that are accurate to second order in the timestep size and first order in the spacestep size and allows explicit calculation of phase saturations and surfactant concentrations as a function of space and time variables. Numerical dispersion (truncation error) present in the two equations tends to mimic the neglected present in the two equations tends to mimic the neglected effects of capillary pressure and diffusion. The effective diffusion constants associated with this effect are proportional to the spacestep size. proportional to the spacestep size. Introduction In a previous paper we presented a system of differential equations that can be used to model oil recovery by chemical flooding. The general system allows for an arbitrary number of components as well as an arbitrary number of phases in an isothermal system. For a binary, two-phase system, the equations reduced to those of the Buckley-Leverett theory under the usual assumptions of incompressibility and each phase containing only a single component, as well as in the more general case where both phases have significant concentrations of both components, but the phases are incompressible and the concentration in one phase is a very weak function of the pressure of the other phase at a given temperature. pressure of the other phase at a given temperature. For a ternary, two-phase system a set of three differential equations was obtained. These equations are applicable to chemical flooding with surfactant, polymer, etc. In this paper, we present a numerical solution to these equations paper, we present a numerical solution to these equations for I D flow in the absence of gravity. Our purpose is to develop a model that includes the physical phenomena influencing oil displacement by surfactant systems and bridges the gap between laboratory displacement tests and reservoir simulation. It also should be of value in defining experiments to elucidate the mechanisms involved in oil displacement by surfactant systems and ultimately reduce the number of experiments necessary to optimize a given surfactant system.

Resistive transition broadening in two-phase polycrystalline YBaCuO

1993 ◽  
Vol 8 (5) ◽  
pp. 957-961 ◽  
Author(s):  
J.C. Abele ◽  
R.L. Bristol ◽  
T.C. Nguyen ◽  
M.W. Ohmer ◽  
L.S. Wood
Keyword(s):  
Magnetic Fields ◽  
Computer Models ◽  
Structured Data ◽  
The Other ◽  
Critical Ratio ◽  
Resistive Transition ◽  
Two Phase ◽  
Two Phases

A model proposed by Tinkham1to explain the resistance versus temperature broadening found in highTcsuperconductors in applied magnetic fields is extended to “foot and knee”-structured data taken on polycrystalline YBa2Cu3O6+δ. The proposed extension involves a series combination of two types of superconductors. For this series combination to result, a critical ratio of the two types of superconductors must be met—a result common to both percolation and randomized cellular autonoma theory. This critical ratio is investigated via statistical computer models of a polycrystalline superconductor having two phases of crystallites—one with substantially lowerJcthan the other.

Study on Two-Phase Fuel Distributions in High-Speed Hot Transverse Air Stream

1986 ◽  
Vol 108 (3) ◽  
pp. 485-490
Author(s):  
Mao-lin Yang ◽  
Shan-jian Gu ◽  
Xiang-yi Li
Keyword(s):  
High Speed ◽  
Empirical Method ◽  
Mass Center ◽  
Two Phase ◽  
Fuel Distribution ◽  
Hot Air ◽  
Air Stream ◽  
Cold Stream ◽  
Fuel Evaporation ◽  
Semi Empirical

It was found that fuel distribution in a hot high-speed transverse air stream differed greatly from that in a cold stream. In a hot air stream there exist two-phase fuel distributions, and hence, two mass center lines extending downstream. Experimental results of fuel distributions are presented. By using the model of trajectory with diffusion and also considering the fuel evaporation, a semi-empirical method to predict two-phase fuel distributions has been developed.

The significance of the boundary between the Rhoscolyn and New Harbour formations on Holy Island, North Wales, to the deformation history of Anglesey

2012 ◽  
Vol 150 (3) ◽  
pp. 519-535 ◽  
Author(s):  
JACK E. TREAGUS ◽  
SUSAN H. TREAGUS ◽  
NIGEL H. WOODCOCK
Keyword(s):  
Lower Cambrian ◽  
Depositional Environment ◽  
High Strain ◽  
The Other ◽  
Deformation History ◽  
Two Phase ◽  
Phase Deformation ◽  
North Wales ◽  
History Of ◽  
Tectonic Features

AbstractThe boundary between the Rhoscolyn and New Harbour formations on Holy Island, Anglesey, has been described as a high strain zone or as a thrust. The boundary is here described at four localities, with reference to the contrasting sedimentary and deformational character of the two formations. At one of these localities, Borth Wen, sandstones and conglomerates at the top of the Rhoscolyn Formation are followed, without any break, by tuffs and then mudstones of the New Harbour Formation. It is concluded that there is clear evidence of depositional continuity across the boundary here, and that both formations subsequently shared a common two-phase deformation. The first (D1) was manifestly different in intensity and scale in the two formations, whereas the second (D2) produced very similar structures in both. The other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of Holy Island, leading us to identify two previously unrecognized major D1 folds in addition to the Rhoscolyn Anticline. At one of these localities (Holyhead), we confirm the presence of Skolithos just below the boundary, supporting radiometric evidence for a lower Cambrian or later age for the Rhoscolyn Formation. A turbidite interpretation for both the Rhoscolyn and New Harbour formations best fits the available evidence. A deep-water depositional environment is still compatible with the sporadic presence of Skolithos burrows, but less so with reported observations of hummocky and swaley cross-stratification lower down the South Stack Group.

scholarly journals HYDRODYNAMIC FEATURES OF SUSPENSIONS AND EMULSIONS FLOWS.

2021 ◽  
Vol 2 (446) ◽  
pp. 99-104
Author(s):  
S.R. Rasulov ◽  
G.R. Mustafayeva
Keyword(s):  
Gas Flow ◽  
Fine Particles ◽  
Mutual Influence ◽  
Transport Coefficients ◽  
Spherical Particles ◽  
Scientific Article ◽  
Two Phase ◽  
Real Picture ◽  
Turbulent Gas Flow ◽  
Gas Pulsations

This scientific article is devoted to the problems associated with the flow of suspensions and emulsions and some simplifications of the real picture of the flow of a polydisperse medium are made. It is also stipulated that differential equations characterizing the motion of suspensions and emulsions should take into account the fundamental discontinuity of the medium and the physicochemical processes of heat and mass transfer occurring in it. Taking into account all these factors, a general equation for multiphase systems is proposed with certain simplifications that do not change. The behavior of particles in two-phase systems, their concentration, collision and coagulation are considered. As a result, it was concluded that there is a multifactorial interaction and mutual influence of both phases in a dispersed flow. A differential equation of motion of a single i-th spherical particle in suspension was proposed, and an equation describing the drag force of a solid spherical particles. Equations of conservation of mass and momentum are presented for one-dimensional laminar motion of two incompressible phases in a gravity field with the same pressure in the phases. Having studied the parameters of the flow of fine particles in a turbulent gas flow, some assumptions were made. It was found that the pulsating motion of particles, performed by them during one period of gas pulsations, can be represented as a change in the pulsating gas velocity in time. The parameter of entrainment of particles by a pulsating medium is an important characteristic in determining the transport coefficients in a turbulent flow. It is concluded that the presence of various kinds of particles in the liquid complicates the problem of solving hydromechanical problems in turbulent and laminar flow, and the assumptions given in the work facilitate the study of this problem.

scholarly journals Clusters Formed by Dumbbell-like One-Patch Particles Confined in Thin Systems

2021 ◽  
Author(s):  
Masahide Sato
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Particle Interaction ◽  
Three Dimensional ◽  
The Other ◽  
Spherical Particles ◽  
Dimensionless Distance ◽  
Large Island ◽  
Cluster Shape

Abstract Performing isothermal-isochoric Monte Carlo simulations, I examine the types of clusters that dumbbell-like one–patch particles form in thin space between two parallel walls, assuming that each particle is synthesized through the merging of two particles, one non-attracting and the other attracting for which, for example, the inter-particle interaction is approximated by the DLVO model. The shape of these dumbbell-like particles is controlled by the ratio of the diameters q of the two spherical particles and by the dimensionless distance l between them. Using a modified Kern–Frenkel potential, I examine the dependence of the cluster shape on l and q. Large island-like clusters are created when q < 1. With increasing q, the clusters become chain-like. When q increases further, elongated clusters and regular polygonal clusters are created. In hte simulations, the cluster shape becomes three-dimensional with increasing l because the thickness of the thin system increases proportionally to l.

Mechanical Properties of Diverse High-Temperature Compounds–Thermal Variation of Microhardness and Crack Formation

1988 ◽  
Vol 133 ◽  
Author(s):  
Robert L. Fleischer
Keyword(s):  
Elastic Moduli ◽  
Crack Formation ◽  
The Other ◽  
Terminal Phase ◽  
Thermal Variation ◽  
Two Phase ◽  
Thermally Activated ◽  
High Melting Temperature ◽  
Binary Compounds ◽  
Single Crystal Plasticity

ABSTRACTMicrohardness vs temperature and elastic moduli have been measured for a suite of intermetallic compounds that melt above 1400°C. Binary intermetallics were selected to represent a variety of crystal structures and yet have optimal combinations of high melting temperature (Tm) and low specific gravity. Some deliberately two-phase alloys were prepared in which one phase is a terminal-phase metal and the other an intermetallic compound.Binary compounds can be described by two patterns. In those where plasticity is difficult, hardness decreased slowly with temperature up to Tm/2, the decrease being no more than that normally shown by the elastic moduli. In those compounds where single crystal plasticity is known (or at least plausible), microhardness decreases more rapidly than do elastic moduli, presumably due to thermally activated slip.

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