Super-Hydrophobic Effect in Single Phase Fluids

2012 ◽  
Author(s):  
Jerzy M. Floryan ◽  
A. Mohammadi
Keyword(s):  
Short Wavelength ◽  
Single Phase ◽  
Solid Wall ◽  
Hydrophobic Effect ◽  
Gas Bubbles ◽  
Smooth Wall ◽  
Flow Topology ◽  
Pressure Drag ◽  
Transverse Grooves ◽  
Two Phases

Super-hydrophobic effect involves capture of gas bubbles in pores of a solid wall, which separates liquid from the solid, resulting in the reduction of the shear drag experienced by the liquid. This effect occurs in the presence of two phases. A similar effect might be produced by creating separation bubbles made of the same fluid through proper shaping of the surface. Use of transverse grooves with a sufficiently short wavelength creates the required flow topology. The shear drag decreases by up to 50% compared with the smooth wall but the interaction pressure drag increases, resulting in only minor reduction in the overall drag. Proper shaping of the grooves may reduce the interaction pressure drag.

Effect of Ferrite Volume Fraction on Mechanical Properties of X80 Pipeline Steel

2014 ◽  
Vol 989-994 ◽  
pp. 212-215
Author(s):  
J. Liu ◽  
G. Zhu ◽  
W. Mao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Work Hardening ◽  
Single Phase ◽  
Volume Fraction ◽  
Pipeline Steel ◽  
X80 Pipeline Steel ◽  
Hardening Behavior ◽  
Two Phases ◽  
Better Than

The effect of volume fraction of ferrite on the mechanical properties including strength, plasticity and wok hardening was systematically investigated in X80 pipeline steel in order to improve the plasticity. The microstructures with different volume fraction of ferrite and bainite were obtained by heat-treatment processing and the mechanical properties were tested. The work hardening behavior was analyzed by C-J method. The results show that the small amount of ferrite could effectively improve the plasticity. The work hardening ability and the ratio of yield/tensile strength with two phases of ferrite/bainite would be obviously better than that with single phase of bainite. The improvement of plasticity could be attributed to the ferrite in which more plastic deformation was afforded.

Study of the equilibrium free surface of a capillary liquid in a toroidal vessel

2021 ◽  
Author(s):  
Y. Zhaokai ◽  
A.N. Temnov
Keyword(s):  
Free Surface ◽  
Liquid Fuel ◽  
Solid Wall ◽  
Intermolecular Forces ◽  
Bond Number ◽  
Space Technology ◽  
Stationary Potential ◽  
Microgravity Conditions ◽  
Two Phases ◽  
Capillary Liquid

The paper considers an axisymmetric problem of determining the forms of equilibrium of liquid in spacecraft toroidal tanks under conditions close to weightlessness. In the absence of significant mass gravitational forces, the behavior of liquid fuel in tanks begins to be determined by surface tension forces, which are intermolecular forces at the interface of two phases. Relying on the principle of stationary potential, we obtained the conditions of equilibrium of the closed system "liquid - gas - solid wall" under microgravity conditions. The study introduces a system of differential equations that determines the form of equilibrium of a liquid in toroidal tanks, the Young — Dupre equation, the condition for the contact of a free surface with a solid wall, and the condition for the conservation of the volume of the liquid. Furthermore, we quantified the influence of various parameters, such as the contact angle α_0, the Bond number B_0, the ratio of the radii of the circles δ=R_0⁄r_0 and the relative filling volume of liquids V_0, on the form of the equilibrium of the capillary liquid. The study of the forms of equilibrium of liquid fuel makes it possible to develop recommendations for the design of intake devices for fuel tanks in rocket and space technology. Findings of research show that the obtained equilibrium surface is also the unperturbed boundary of the region occupied by liquid fuel, which gives necessary information for further investigation of the spacecraft dynamics.

scholarly journals Growth and Characterization of BxGa1−xN on 6H-SiC (0001) by Movpe

1999 ◽  
Vol 4 (S1) ◽  
pp. 429-434 ◽  
Author(s):  
C. H. Wei ◽  
Z. Y. Xie ◽  
J. H. Edgar ◽  
K. C. Zeng ◽  
J. Y. Lin ◽  
...  
Keyword(s):  
Single Phase ◽  
Band Edge Emission ◽  
Reactant Ratio ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Edge Emission ◽  
X Ray ◽  
Two Phases

Boron was incorporated into GaN in order to determine its limits of solubility, its ability of reducing the lattice constant mismatch with 6H-SiC, as well as its effects on the structural and optical properties of GaN epilayers. BxGa1−xN films were deposited on 6H-SiC (0001) substrates at 950 °C by low pressure MOVPE using diborane, trimethylgallium, and ammonia as precursors. A single phase alloy with x=0.015 was successfully produced at a gas reactant B/Ga ratio of 0.005. Phase separation into pure GaN and BxGa1−xN alloy with x=0.30 was deposited for a B/Ga reactant ratio of 0.01. This is the highest B fraction of the wurtzite structure alloy ever reported. For B/Ga ratio ≥ 0.02, no BxGa1−xN was formed, and the solid solution contained two phases: wurtzite GaN and BN based on the results of Auger and x-ray diffraction. The band edge emission of BxGa1−xN varied from 3.451 eV for x=0 with FWHM of 39.2 meV to 3.465 eV for x=0.015 with FWHM of 35.1 meV. The narrower FWHM indicated that the quality of GaN epilayer was improved with small amount of boron incorporation.

An STATCOM-based Hybrid Shunt Compensation Scheme Capable of Damping Subsynchronous Resonance

2017 ◽  
Vol 6 (3) ◽  
pp. 150
Author(s):  
F. Reyhaneh Mehdizadeh ◽  
Daryoush Nazarpour
Keyword(s):  
Single Phase ◽  
Simulation Analysis ◽  
Static Synchronous Compensator ◽  
Control Loops ◽  
Subsynchronous Resonance ◽  
Three Phase ◽  
Two Phases ◽  
Shunt Compensation ◽  
Shunt Capacitor ◽  
Potential Use

The paper presents the potential use of supplemental control of a new economical phase imbalanced shunt compensation concept for damping sub synchronous resonance (SSR) oscillations. In this scheme, the shunt capacitive compensation in one phase is created by using a Single-Phase Static Synchronous Compensator (STATCOM) in parallel with a fixed capacitor (Cc), and the other two phases are compensated by fixed shunt capacitor (C). The proposed arrangement would, certainly, be economically attractive when compared with a full three-phase STATCOM which have been used/proposed for power swings and SSR damping. SSR mitigation is achieved by introducing a supplemental signal into the control loops of single phase STATCOM. The validity and effectiveness of the proposed structure and supplemental control are demonstrated on a modified version of the IEEE second benchmark model for computer simulation of sub synchronous resonance by means of time domain simulation analysis using the Matlab program.

The rapid distortion of two-way coupled particle-laden turbulence

2019 ◽  
Vol 877 ◽  
pp. 82-104 ◽  
Author(s):  
M. Houssem Kasbaoui ◽  
Donald L. Koch ◽  
Olivier Desjardins
Keyword(s):  
Single Phase ◽  
Density Fluctuations ◽  
Gravitational Potential Energy ◽  
Inertial Particles ◽  
Mass Loading ◽  
Number Density ◽  
Turbulence Statistics ◽  
Preferential Sampling ◽  
Gravitational Loading ◽  
Two Phases

In this study, we address the modification of sheared turbulence by dispersed inertial particles. The preferential sampling of the straining regions of the flow by inertial particles in turbulence leads to an inhomogeneous distribution of particles. The strong gravitational loading exerted by the highly concentrated regions results in anisotropic alteration of turbulence at small scales in the direction of gravity. These effects are investigated in a rapid distortion theory (RDT) extended for two-way coupled particle-laden flows. To make the analysis tractable, we assume that particles have small but non-zero inertia. In the classical results for single-phase flows, the RDT assumption of fast shearing compared to the turbulence time scales leads to the distortion and shear-induced production of turbulence. In particle-laden turbulence, the coupling between the two phases under rapid shearing induces number density fluctuations that convert gravitational potential energy to turbulent kinetic energy and modulate the turbulence spectrum in a manner that increases with mass loading. Turbulence statistics obtained from RDT are compared with Euler–Lagrange simulations of homogeneously sheared particle-laden turbulence.

Growth and Characterization of BxGal-xN on 6H-SiC (0001) by MOVPE

1998 ◽  
Vol 537 ◽  
Author(s):  
C. H. Wei ◽  
Z. Y. Xie ◽  
J. H. Edgar ◽  
K. C. Zeng ◽  
J. Y. Lin ◽  
...  
Keyword(s):  
Single Phase ◽  
Band Edge Emission ◽  
Reactant Ratio ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Edge Emission ◽  
X Ray ◽  
Two Phases

AbstractBoron was incorporated into GaN in order to determine its limits of solubility, its ability of reducing the lattice constant mismatch with 6H-SiC, as well as its effects on the structural and optical properties of GaN epilayers. BxGal-xN films were deposited on 6H-SiC (0001) substrates at 950 °C by low pressure MOVPE using diborane, trimethylgallium, and ammonia as precursors. A single phase alloy with x=0.015 was successfully produced at a gas reactant B/Ga ratio of 0.005. Phase separation into pure GaN and BxGal-xN alloy with x=0.30 was deposited for a B/Ga reactant ratio of 0.01. This is the highest B fraction of the wurtzite structure alloy ever reported. For B/Ga ratio ≥ 0.02, no BxGal-xN was formed, and the solid solution contained two phases: wurtzite GaN and BN based on the results of Auger and x-ray diffraction. The band edge emission of BxGal-xN varied from 3.451 eV for x=0 with FWHM of 39.2 meV to 3.465 eV for x=0.015 with FWHM of 35.1 meV. The narrower FWHM indicated that the quality of GaN epilayer was improved with small amount of boron incorporation.

SYNTHESIS, CHARACTERIZATION, AND SELF-CONTROLLED ORTHORHOMBIC TO TETRAGONAL POLYMORPHIC TRANSFORMATION IN BaTiO3 NANOPARTICLES

2007 ◽  
Vol 21 (25) ◽  
pp. 1697-1714
Author(s):  
S. RAM ◽  
A. JANA ◽  
T. K. KUNDU
Keyword(s):  
Composite Structure ◽  
Single Phase ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Volume ◽  
Proposed Model ◽  
Diffraction Peaks ◽  
Two Phases ◽  
O Phase

The phase formation and thermal-induced phase transformation are studied in BaTiO 3 nanoparticles. 2 h of heating a polymer precursor at 550°C in air formed a single phase BaTiO 3 of 15 nm average crystallite size D. The X-ray diffraction peaks are analyzed assuming a P nma orthorhombic (o) crystal structure of lattice parameters a = 0.6435 nm , b = 0.5306 nm , and c = 0.8854 nm . The lattice volume V = 0.3023 nm 3, with z = 4 formula units, yields a density ρ = 5.124 g/cm 3. This is a new polymorph in comparison to well-known P m3m tetragonal (t) structure, V = 0.0644 nm 3 or ρ = 6.016 g/cm 3 (z = 1). An o ↦ t transformation appears on heating at temperature as high as 650°C in air. A proposed model explains the transformation above a certain D value in terms of the Gibbs free energy. Unless heating above 750°C, the two phases coexist in a composite structure (D≤27 nm ), with as much residual o-phase trace as ~28 vol%. As a function of temperature both the phases decrease in the V values up to 0.2975 and 0.0643 nm3 at 750°C respectively (0.0650 nm3 at 650°C). This is an important parameter for designing useful ferroelectric and other properties in a hybrid composite structure.

Numerical Simulation of Thermofluid Characteristics of Two-Phase Slug Flow in Microchannels

2010 ◽  
Author(s):  
A. Mehdizadeh ◽  
S. A. Sherif ◽  
W. E. Lear
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Slug Flow ◽  
Single Phase ◽  
Solid Wall ◽  
Heat Transfer Characteristics ◽  
Two Phase

A fundamental study of heat transfer characteristics of two-phase slug flow in microchannels is carried out employing the Volume-of-Fluid (VOF) method. Despite of the fact that numerical simulations of two-phase flows in microchannels have been attempted by many investigators, most efforts seem to have failed in correctly capturing the flow physics, especially those pertaining to the slug flow regime characteristics. The presence of a thin liquid film in the order of 10 μm around the bubble is a contributing factor to the above difficulty. Typically, liquid films have a significant effect on the flow field and heat transfer characteristics. In the simulations reported in this paper, the film is successfully captured and a very high local convective heat transfer coefficient is observed in the film region. A strong coupling between the conductive heat transfer in the solid wall and the convective heat transfer in the flow field is observed and characterized. Results showed that unsteady heat transfer through the solid wall in the axial direction is comparable to that in the radial direction. Results also showed that a fully developed condition could be achieved fairly quickly compared to single-phase flows. The fully developed condition is defined based on the Peclet number (Pe) and a dimensionless length of the liquid slug. Local and time-averaged Nusselt numbers for slug flows are reported for the first time. It was found that significant improvements in the heat transfer coefficient could be achieved by short slugs where the Nu number was found to be 610% higher than in single-phase flows. The study revealed new findings related to slug flow heat transfer in microchannels with constant wall heat flux.

Processing, Structure, Texture and Microtexture in Titanium Alloys

2012 ◽  
Vol 710 ◽  
pp. 66-84 ◽  
Author(s):  
Dipankar Banerjee ◽  
Adam L. Pilchak ◽  
James C. Williams
Keyword(s):  
Titanium Alloys ◽  
Single Phase ◽  
Thermomechanical Processing ◽  
Strong Dependence ◽  
Two Phase ◽  
Β Phase ◽  
Phase Fields ◽  
Deformation And Heat Treatment ◽  
Two Phases ◽  
The Individual

We review the effect of processing on structure and texture in titanium alloys, focusing on the understanding of this relationship that has evolved over the last decade. Thermomechanical processing cycles for these alloys involve deformation and heat treatment in single phase β and two phase, α+β, phase fields, and involves a complex interplay between deformation and recrystallization textures of the individual phases, textures arising from the crystallographic relationship between the two phases, and the scale of microstructure evolution. We explore these interactions and trace the strong dependence of thermomechanical pathways on the final structure and texture.

Structure/property observations for Al–Ti–Cr intermetallic alloys

1994 ◽  
Vol 9 (2) ◽  
pp. 255-258 ◽  
Author(s):  
J.L. Klansky ◽  
J.P. Nic ◽  
D.E. Mikkola
Keyword(s):  
Mechanical Properties ◽  
Single Phase ◽  
Intermetallic Alloys ◽  
Structure Property ◽  
Multiphase Alloys ◽  
Microstructures And Mechanical Properties ◽  
Two Phases ◽  
The Individual

The microstructures and mechanical properties of single phase and multiphase alloys are reported for Al-rich intermetallic alloys containing up to 45 at. % Ti and as much as 68 at. % Cr. Among the individual phases formed in these alloys, TiAl and tau (Al67Cr8Ti25) had both the lowest hardnesses and the greatest resistance to cracking. Additionally, the presence of these two phases in multiphase alloys improved mechanical properties.

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