Acoustic Properties of Solid-Liquid Mixtures and the Limits of Ultrasound Diagnostics—I: Experiments (Data Bank Contribution)

1993 ◽  
Vol 115 (4) ◽  
pp. 665-675 ◽  
Author(s):  
C. M. Atkinson ◽  
H. K. Kyto¨maa
Keyword(s):  
Spatial Resolution ◽  
Liquid Mixtures ◽  
Acoustic Properties ◽  
Present System ◽  
Linear Superposition ◽  
Two Phase ◽  
Ultrasound Diagnostics ◽  
Wide Range ◽  
Silica Beads ◽  
Solid Liquid

Ultrasound as a technique for interrogating two-phase mixtures has the advantages of being nonintrusive, it has a very high frequency response, and is able to penetrate typically opaque highly concentrated mixtures. There exists, however, an inherent compromise in the choice of the frequency of the ultrasound between maximizing spatial resolution and ensuring adequate beam penetration. To this end, the propagation of ultrasound in solid-liquid mixtures has been investigated experimentally for a range of frequencies and concentrations of the dispersed phase. The measured attenuation has been shown to depend roughly linearly on frequency for 0.1<kr<0.75 (where the wavenumber k = 2π/λ, and λ and r are the wavelength and particle radius, respectively), and quadratically for kr > 0.75. As a function of solids concentration, the attenuation displays a maximum at a solids fraction of about 30 percent for the present system of silica beads in water. This robust and reproducible result contradicts models of attenuation that rely on linear superposition of single particle effects. The intensity field produced by a circular disk transducer in a two phase medium at kr~1 shows excellent agreement with the Rayleigh integral with a modified wavenumber and attenuation parameter, and it allows for the prediction of the transducer beam geometry in two phase mixtures for a wide range of frequencies and solids fractions. The limitations of ultrasonic wave propagation as a nonintrusive diagnostic technique, in terms of spatial resolution, have been discussed. Acknowledging these limitations, an ultrasonic instrument for determining the velocity of moving particles at or near maximum packing was built. Preliminary results from this prototypical ultrasonic Doppler velocimeter show good agreement with observations of the settling velocity of silica beads at high concentrations.

Optimization Simulation on Blade Number of Grit Chambers with Rotational Flow

2013 ◽  
Vol 368-370 ◽  
pp. 1894-1897
Author(s):  
Rui Rui Sun ◽  
Xiao Ling Wang ◽  
Jia Min Tu ◽  
Xue Fei Ao
Keyword(s):  
Removal Efficiency ◽  
Collision Term ◽  
Rotational Flow ◽  
Particle Removal ◽  
Complex Flow ◽  
Two Phase ◽  
Wide Range ◽  
Optimization Simulation ◽  
High Turbidity ◽  
Solid Liquid

The grit chambers with rotational flow find wide range of application for the treatment of sandstone wastewater in hydropower stations. Aiming at the high-turbidity solid-liquid two-phase problem of a complex flow pattern, an Eulerian-Eulerian two-phase model was built, which can describe the collision term between particles in sandstone wastewater. By using CFD technology, the velocity distribution of flow at the blade position was analyzed and the different effects caused by blade numbers to the particle removal efficiency were discussed. The results show that the removal efficiency of grit chamber with rotational flow increased gradually at first and then decreased slightly. Then the number of blade is four, the optimum removal efficiency can be reached, which provided theoretical and referential basis for engineering design and operation.

Performance analysis of air-lift pump design

2004 ◽  
Vol 218 (10) ◽  
pp. 1155-1161 ◽  
Author(s):  
G K Awari ◽  
P M Ardhapurkar ◽  
D G Wakde ◽  
L B Bhuyar
Keyword(s):  
Liquid Mixtures ◽  
Operating Conditions ◽  
Design Parameters ◽  
Established Method ◽  
Two Phase ◽  
Mathematical Functions ◽  
Pump Design ◽  
User Friendly ◽  
Solid Liquid ◽  
Air Lift

The air-lift pump is a well-established method for vertical transport of liquids and solid-liquid mixtures. The objectives of the present study are to evaluate the performance of a pump under predetermined operating conditions and to optimize the related parameters for the use of the pump for two-phase mixtures of air and water when a compressor is readily available. This paper is focused on the general mathematical functions applicable to air-lift pump installations. The effect of various design parameters on the performance of air-lift pump is presented. A user-friendly computer program is developed on the basis of the optimization of influencing variables. This program will be useful for the design and installation of an air-lift pump handling air-water mixtures. A comparative study of an air-lift pump with a centrifugal pump handling two-phase mixtures is also discussed in the paper.

scholarly journals Supersonic flow of two-phase gas- droplet flows in nozzles

2019 ◽  
Vol 21 (3) ◽  
pp. 86-98
Author(s):  
A. I. Sharapov ◽  
A. A. Chernykh ◽  
A. V. Peshkova
Keyword(s):  
Liquid Mixtures ◽  
Rocket Engines ◽  
Two Phase ◽  
Acoustic Effect ◽  
Practical Applications ◽  
Wide Range ◽  
Phase Medium ◽  
Integral Energy ◽  
Energy Equations ◽  
Droplet Flows

For practical applications, the description of processes occurring during the flow of two-phase gas-liquid mixtures requires a simple physical and mathematical model that describes the behavior of a two-phase medium in the entire range of phase concentrations changes and in a wide range of pressure changes. Problems of this kind arise in various branches of industry and technology. In the space industry, one often has to deal with the movement of various gases in rocket nozzles, consider the combustion, condensation of various vapors on the nozzle walls and their further impact on the velocity sublayer at the nozzle wall. The large acoustic effect arising from the engines affects the gas-liquid mixture in the nozzles of rocket engines. In the metal industry, metal cooling occurs with the help of nozzles in which the emulsion mixture is supplied under high overpressure. But this is only a short list of applied issues in which one has to deal with a problem of this type. The paper presents the results and directions of study of the problems of two-phase dispersed gas-droplet flows in the nozzles. The main methods of investigation of two- phase heterogeneous flows are described. The main characteristics of heterogeneous two-phase flows in the nozzles, which were confirmed by experimental results, are presented. The calculation of the air-droplet flow in the Laval nozzle is given. The technique, which is based on integral energy equations for two-phase dispersed flows, is described. The main problems and questions concerning the further description and studying of two-component flows are stated.

General Trend of Negative Transference Number in Li Salt/Ionic Liquid Mixtures

2019 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Ionic Liquid ◽  
Transference Number ◽  
Liquid Mixtures ◽  
Single Linkage ◽  
Self Diffusion ◽  
Wide Range ◽  
Single Linkage Cluster ◽  
Concentrated Solution ◽  
The One ◽  
Dynamics Simulations

We show that strong cation-anion interactions in a wide range of lithium-salt/ionic liquid mixtures result in a negative lithium transference number, using molecular dynamics simulations and rigorous concentrated solution theory. This behavior fundamentally deviates from the one obtained using self-diffusion coefficient analysis and agrees well with experimental electrophoretic NMR measurements, which accounts for ion correlations. We extend these findings to several ionic liquid compositions. We investigate the degree of spatial ionic coordination employing single-linkage cluster analysis, unveiling asymmetrical anion-cation clusters. Additionally, we formulate a way to compute the effective lithium charge that corresponds to and agrees well with electrophoretic measurements and show that lithium effectively carries a negative charge in a remarkably wide range of chemistries and concentrations. The generality of our observation has significant implications for the energy storage community, emphasizing the need to reconsider the potential of these systems as next generation battery electrolytes.<br>

Generalized Heterodyne Configurations for Photo-induced Force Microscopy

2019 ◽  
Author(s):  
Le Wang ◽  
Devon Jakob ◽  
Haomin Wang ◽  
Alexis Apostolos ◽  
Marcos M. Pires ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Repetition Rate ◽  
Modulation Frequency ◽  
High Harmonic ◽  
Chemical Imaging ◽  
Heterodyne Detection ◽  
Force Microscopy ◽  
Wide Range ◽  
The Difference ◽  
Afm Cantilever

<div>Infrared chemical microscopy through mechanical probing of light-matter interactions by atomic force microscopy (AFM) bypasses the diffraction limit. One increasingly popular technique is photo-induced force microscopy (PiFM), which utilizes the mechanical heterodyne signal detection between cantilever mechanical resonant oscillations and the photo induced force from light-matter interaction. So far, photo induced force microscopy has been operated in only one heterodyne configuration. In this article, we generalize heterodyne configurations of photoinduced force microscopy by introducing two new schemes: harmonic heterodyne detection and sequential heterodyne detection. In harmonic heterodyne detection, the laser repetition rate matches integer fractions of the difference between the two mechanical resonant modes of the AFM cantilever. The high harmonic of the beating from the photothermal expansion mixes with the AFM cantilever oscillation to provide PiFM signal. In sequential heterodyne detection, the combination of the repetition rate of laser pulses and polarization modulation frequency matches the difference between two AFM mechanical modes, leading to detectable PiFM signals. These two generalized heterodyne configurations for photo induced force microscopy deliver new avenues for chemical imaging and broadband spectroscopy at ~10 nm spatial resolution. They are suitable for a wide range of heterogeneous materials across various disciplines: from structured polymer film, polaritonic boron nitride materials, to isolated bacterial peptidoglycan cell walls. The generalized heterodyne configurations introduce flexibility for the implementation of PiFM and related tapping mode AFM-IR, and provide possibilities for additional modulation channel in PiFM for targeted signal extraction with nanoscale spatial resolution.</div>

Soil Chemical Pollution and Aggressive Pathologies

2018 ◽  
Vol 69 (8) ◽  
pp. 2278-2282
Author(s):  
Stelian Ioan Morariu ◽  
Letitia Doina Duceac ◽  
Alina Costina Luca ◽  
Florina Popescu ◽  
Liliana Pavel ◽  
...  
Keyword(s):  
Health Care Professionals ◽  
Scientific Progress ◽  
Volcanic Eruptions ◽  
Chemical Pollution ◽  
Optimal Parameters ◽  
Chemical Pollutants ◽  
Wide Range ◽  
Health Physician ◽  
Solid Liquid

Maintaining the soil in optimal parameters is vital for mankind, given its essential role in providing the alimentary base, as well as its extremely slow formation and regeneration (hundreds or thousands of years). The direct and indirect pollution of the soil and especially its chemical pollution represent a corollary of other types of pollution, given that it is produced by solid, liquid and gaseous residues. It may be involved in a wide range of diseases (respiratory, cardiovascular, digestive, renal, haematological, osteoarticular, neurological) of allergic, infectious, degenerative or neoplastic nature, from infancy to the old age. Although there are natural causes of soil pollution (e.g. volcanic eruptions), most pollutants come from human activities, which are the most incriminated in its pollution, degradation and erosion at an accelerated pace. The growing concern of all nations for the adoption of measures to limit the chemical pollution of the soil is partially found so far in viable and effective solutions intended to combat soil contamination and degradation and ensure its restoration. Chemical industrialization leads to technical and scientific progress, but at the same time it can develop related pathologies, which means that the role of the occupational health physician is essential in ensuring prophylaxis and the early detection of occupational diseases. Besides that, the role of the pediatrician is equally precious for the detection of specific diseases caused by chemical pollutants to children, because they will develop into adults with pathological stigma.The chemical pollution of the soil is a major challenge for ecologists, given that it is an important risk factor for many types of afflictions. It requires maximum attention from civil society, health care professionals and government institutions. The specialist in occupational medicine, as well as the pediatrician bear an essential responsibility in both, prevention and treatment.

Features of spatial shock-wave flows in vapor-gas-liquid mixtures

2014 ◽  
Vol 10 ◽  
pp. 27-31
Author(s):  
R.Kh. Bolotnova ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Waves ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Pressure Vessels ◽  
Water Mixture ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

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