Syncronous Visualization of Flow Patterns and Correlative Physical Parameters

1992 ◽  
pp. 333-337
Author(s):  
Wei Qing-ding ◽  
Wang Wen-bao ◽  
Li Chang-Lin ◽  
Du Xiang-dong
Keyword(s):  
Flow Patterns ◽  
Physical Parameters

Average Physical Parameters in an Air-Water Two-Phase Flow in a Small, Square-Sectioned Channel

1994 ◽  
Vol 116 (2) ◽  
pp. 247-254 ◽  
Author(s):  
J. K. Keska ◽  
R. D. Fernando
Keyword(s):  
Experimental Data ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Full Range ◽  
Flow Patterns ◽  
Physical Parameters ◽  
Phase Flow ◽  
Spatial Concentration ◽  
Two Phase ◽  
Concentration Measurements

This experimental study focuses on an adiabatic two-phase air-water flow generated in a small, horizontal, 6.35 mm square channel. Pressure and temperature were near standard conditions. Experimental data and correlations available in the literature, generally, do not consider the full range of concentration, small cross-sectional areas and direct physical parameters, such as concentration (void fraction) and/or phase velocities. Based on the direct measurement of in-situ spatial concentration (in a full range of concentrations, including gas and liquid phases only), and flow-pattern determination, the experimental data from the study are compared with data from the literature and with prediction by the generally accepted Lockhart-Martinelli’s and Chen’s models. Spatial concentration measurements were made with a computer-based system developed and built by the authors. Pressure drop over a length of the channel was also measured with pressure transducers. These measurements were made for a variety of flow conditions which encompassed bubble, slug, plug, and annular flow regimes. Flow patterns were established, and both mean and fluctuating components of the concentration measurements were used to objectively identify the flow patterns. These results, together with visual enhanced observation (stroboscope) supplemented with a high-speed CCD camera recording enhanced with dye injection, were used to obtain flow-pattern maps and compared with the literature. Spatial concentration is shown to be a key physical parameter in describing the state of the mixture in two-phase flow.

Choking Phenomena in a Lung-Like Model

1987 ◽  
Vol 109 (1) ◽  
pp. 1-9 ◽  
Author(s):  
David Elad ◽  
Roger D. Kamm ◽  
Ascher H. Shapiro
Keyword(s):  
Fluid Flow ◽  
Flow Patterns ◽  
Physical Parameters ◽  
Forced Expiration ◽  
Flow Limitation ◽  
Conducting System ◽  
Dimensional Model ◽  
One Dimensional

A simple, continuous, one-dimensional model for the geometry and structure of the bronchial airways is used for the analysis of fluid flow patterns which have been observed in forced expiration maneuvers. Various phenomena within the conducting system associated with flow limitation are investigated: (a) the conditions in which a “choke” (flow limitation) can occur in a compliant system; (b) theoretical flows that are physically impossible; (c) the possibility of having elastic jumps downstream of the choke point; (d) perturbations in the physical parameters of the conducting system.

Modeling of a Three-Dimensional Single-Phase Direct Methanol Fuel Cell

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Alireza Bayat ◽  
Nicholas Maus ◽  
Faramarz Gordaninejad
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Single Phase ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Full Scale ◽  
Scale Model ◽  
Physical Parameters ◽  
Direct Methanol ◽  
Methanol Fuel Cell

A three-dimensional, full-scale, single-phase finite element model has been developed for a liquid-fed direct methanol fuel cell (DMFC) with serpentine flow patterns. Equations for conservation of mass, momentum, and species are coupled with electrochemical kinetics in anode and cathode catalyst layers (CCLs). At the anode and cathode sides, only the liquid and the gas phases are considered, respectively. The significant benefit of a full-scale model is that the effect of physical parameters and distribution of the concentration of species can be realized in different channels for a desired section within the flow patterns. The model is used to study the effects of different operating parameters on fuel cell performance. Comparing numerical and experimental results demonstrate that the single-phase model slightly over-predicts the results for polarization plot. The modeling results also show that the porosity, temperature, and methanol concentration play a key role in affecting the DMFC polarization curve.

Some Results of the Spectroscopic Study of Four Close Binary Systems of Early Spectral Types

1965 ◽  
Vol 5 ◽  
pp. 120-130
Author(s):  
T. S. Galkina
Keyword(s):  
Spectroscopic Study ◽  
Spectral Type ◽  
Spectroscopic Investigation ◽  
Binary Systems ◽  
Quantitative Information ◽  
Close Binary ◽  
Physical Parameters ◽  
Absorption And Emission ◽  
Close Binary Systems ◽  
Quantitative Estimates

It is necessary to have quantitative estimates of the intensity of lines (both absorption and emission) to obtain the physical parameters of the atmosphere of components.Some years ago at the Crimean observatory we began the spectroscopic investigation of close binary systems of the early spectral type with components WR, Of, O, B to try and obtain more quantitative information from the study of the spectra of the components.

A theory of contamination in electron microscopes by surface diffusion

1978 ◽  
Vol 36 (1) ◽  
pp. 116-117
Author(s):  
J.T. Fourie
Keyword(s):  
Electron Beam ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Physical Parameters ◽  
Carbon Compounds ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Primary Electrons ◽  
Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

Electron Microscopy in the Study of Natural Phytoplankton Assemblages

1985 ◽  
Vol 43 ◽  
pp. 620-623
Author(s):  
Linda Sicko-Goad
Keyword(s):  
Electron Microscopy ◽  
Aquatic Environment ◽  
Size Range ◽  
Physical Parameters ◽  
Specific Information ◽  
Phytoplankton Assemblages ◽  
Phytoplankton Productivity ◽  
Ecosystem Effects ◽  
Time Of Year ◽  
Species Specific

Although the use of electron microscopy and its varied methodologies is not usually associated with ecological studies, the types of species specific information that can be generated by these techniques are often quite useful in predicting long-term ecosystem effects. The utility of these techniques is especially apparent when one considers both the size range of particles found in the aquatic environment and the complexity of the phytoplankton assemblages.The size range and character of organisms found in the aquatic environment are dependent upon a variety of physical parameters that include sampling depth, location, and time of year. In the winter months, all the Laurentian Great Lakes are uniformly mixed and homothermous in the range of 1.1 to 1.7°C. During this time phytoplankton productivity is quite low.

A New Numerical Model for Electron-Probe Analysis at High Depth Resolution

1996 ◽  
Vol 54 ◽  
pp. 490-491
Author(s):  
P.-F. Staub ◽  
C. Bonnelle ◽  
F. Vergand ◽  
P. Jonnard
Keyword(s):  
Electron Probe ◽  
Surface Segregation ◽  
Depth Distribution ◽  
Computing Time ◽  
Depth Resolution ◽  
Physical Parameters ◽  
Electron Probe Analysis ◽  
Interface Phases ◽  
Excitation Conditions ◽  
High Depth

Characterizing dimensionally and chemically nanometric structures such as surface segregation or interface phases can be performed efficiently using electron probe (EP) techniques at very low excitation conditions, i.e. using small incident energies (0.5<E0<5 keV) and low incident overvoltages (1<U0<1.7). In such extreme conditions, classical analytical EP models are generally pushed to their validity limits in terms of accuracy and physical consistency, and Monte-Carlo simulations are not convenient solutions as routine tools, because of their cost in computing time. In this context, we have developed an intermediate procedure, called IntriX, in which the ionization depth distributions Φ(ρz) are numerically reconstructed by integration of basic macroscopic physical parameters describing the electron beam/matter interaction, all of them being available under pre-established analytical forms. IntriX’s procedure consists in dividing the ionization depth distribution into three separate contributions:

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