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Sample records for absorption liquid flow

  1. Optical Absorption in Liquid Semiconductors

    NASA Astrophysics Data System (ADS)

    Bell, Florian Gene

    An infrared absorption cell has been developed which is suitable for high temperature liquids which have absorptions in the range .1-10('3) cm('-1). The cell is constructed by clamping a gasket between two flat optical windows. This unique design allows the use of any optical windows chemically compatible with the liquid. The long -wavelength limit of the measurements is therefore limited only by the choice of the optical windows. The thickness of the cell can easily be set during assembly, and can be varied from 50 (mu)m to .5 cm. Measurements of the optical absorption edge were performed on the liquid alloy Se(,1-x)Tl(,x) for x = 0, .001, .002, .003, .005, .007, and .009, from the melting point up to 475(DEGREES)C. The absorption was found to be exponential in the photon energy over the experimental range from 0.3 eV to 1.2 eV. The absorption increased linearly with concentration according to the empirical relation (alpha)(,T)(h(nu)) = (alpha)(,1) + (alpha)(,2)x, and the absorption (alpha)(,1) was interpreted as the absorption in the absence of T1. (alpha)(,1) also agreed with the measured absorption in 100% Se at corresponding temperatures and energies. The excess absorption defined by (DELTA)(alpha) = (alpha)(,T)(h(nu))-(alpha)(,1) was interpreted as the absorption associated with Tl and was found to be thermally activated with an activation energy E(,t) = 0.5 eV. The exponential edge is explained as absorption on atoms immersed in strong electric fields surrounding ions. The strong fields give rise to an absorption tail similar to the Franz-Keldysh effect. A simple calculation is performed which is based on the Dow-Redfield theory of absorption in an electric field with excitonic effects included. The excess absorption at low photon energies is proportional to the square of the concentration of ions, which are proposed to exist in the liquid according to the relation C(,i) (PROPORTIONAL) x(' 1/2)(.)e('-E)t('/kT), which is the origin of the thermal activation

  2. Visible absorption spectrum of liquid ethylene

    PubMed Central

    Nelson, Edward T.; Patel, C. Kumar N.

    1981-01-01

    The visible absorption spectrum of liquid ethylene at ≈ 108 K from 5500 Å to 7200 Å was measured by using a pulsed tunable dye laser, immersed-transducer, gated-detection opto-acoustic spectroscopy technique. The absorption features show the strongest band with an absorption coefficient of ≈2 × 10-2 cm-1 and the weakest band with an absorption coefficient of ≈1 × 10-4 cm-1. Proposed assignments of the observed absorption peaks involve combinations of overtones of local and normal modes of vibration of ethylene. PMID:16592978

  3. Polymer-supported ionic liquid solid phase extraction for trace inorganic and organic mercury determination in water samples by flow injection-cold vapor atomic absorption spectrometry.

    PubMed

    Escudero, Leticia B; Olsina, Roberto A; Wuilloud, Rodolfo G

    2013-11-15

    A simple and green technique named polymer-supported ionic liquid solid phase extraction (PSIL-SPE) was developed for mercury (Hg) species determination. Inorganic Hg (InHg) species was complexed with chloride ions followed by its introduction into a flow injection on-line system to quantitatively retain the anionic chlorocomplex (HgCl4(2-)) in a column packed with CYPHOS(®) IL 101-impregnated resin. The trapped InHg was then reduced with stannous chloride (SnCl2) and eluted with the same flow of reducing agent followed by cold vapor atomic absorption spectrometry (CV-AAS) detection. Organic mercury species (OrgHg) did not interact with the impregnated resin and were not retained into the column. Total concentration of OrgHg was evaluated by difference between total Hg and InHg concentration. A 95% extraction efficiency was achieved for InHg when the procedure was developed under optimal experimental conditions. The limit of detection obtained for preconcentration of 40 mL of sample was 2.4 ng L(-1) InHg. The relative standard deviation (RSD) was 2.7% (at 1 µg L(-1) InHg and n=10) calculated from the peak height of absorbance signals (Gaussian-shape and reproducible peaks). This work reports the first polymer-supported IL solid phase extraction approach implemented in a flow injection on-line system for determination of Hg species in mineral, tap and river water samples. PMID:24148384

  4. Liquid/Gas Flow Mixers

    NASA Technical Reports Server (NTRS)

    Fabris, Gracio

    1994-01-01

    Improved devices mix gases and liquids into bubbly or foamy flows. Generates flowing, homogeneous foams or homogeneous dispersions of small, noncoalescing bubbles entrained in flowing liquids. Mixers useful in liquid-metal magnetohydrodynamic electric-power generator, froth flotation in mining industry, wastewater treatment, aerobic digestion, and stripping hydrocarbon contaminants from ground water.

  5. Liquid for absorption of solar heat

    SciTech Connect

    Nakamura, T.; Iwamoto, Y.; Kadotani, K.; Marui, T.

    1984-11-13

    A liquid for the absorption of solar heat, useful as an heat-absorbing medium in water heaters and heat collectors comprises: a dispersing medium selected from the group consisting of propylene glycol, mixture of propylene glycol with water, mixture of propylene glycol with water and glycerin, and mixture of glycerin with water, a dispersant selected from the group consisting of polyvinylpyrrolidone, caramel, and mixture of polyvinylpyrrolidone with caramel, and a powdered activated carbon as a black coloring material.

  6. Liquid-absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, S.

    1990-12-11

    A system is described for detecting trace concentrations of an analyte in air and includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container in which is disposed a wettable material extending substantially the entire length of the container. One end of the wettable material is continuously wetted with an analyte-sorbing liquid, which flows to the other end of the container. Sample air is flowed through the container in contact with the wetted material for trapping and preconcentrating the traces of analyte in the sorbing liquid, which is then collected at the other end of the container and discharged to the detector. The wetted material may be a wick comprising a bundle of fibers, one end of which is immersed in a reservoir of the analyte-sorbing liquid, or may be a liner disposed on the inner surface of the container, with the sorbing liquid being centrifugally dispersed onto the liner at one end thereof. The container is preferably vertically oriented so that gravity effects the liquid flow. 4 figs.

  7. Liquid-absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, Solomon

    1990-01-01

    A system for detecting trace concentrations of an analyte in air and includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container in which is disposed a wettable material extending substantially the entire length of the container. One end of the wettable material is continuously wetted with an analyte-sorbing liquid, which flows to the other end of the container. Sample air is flowed through the container in contact with the wetted material for trapping and preconcentrating the traces of analyte in the sorbing liquid, which is then collected at the other end of the container and discharged to the detector. The wetted material may be a wick comprising a bundle of fibers, one end of which is immersed in a reservoir of the analyte-sorbing liquid, or may be a liner disposed on the inner surface of the container, with the sorbing liquid being centrifugally dispersed onto the liner at one end thereof. The container is preferably vertically oriented so that gravity effects the liquid flow.

  8. High throughput liquid absorption preconcentrator sampling instrument

    DOEpatents

    Zaromb, Solomon; Bozen, Ralph M.

    1992-01-01

    A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis.

  9. A flow-through reaction cell for in situ X-ray diffraction and absorption studies of heterogeneous powder-liquid reactions and phase transformations.

    PubMed

    Ferrer, Pilar; da Silva, Iván; Rubio-Zuazo, Juan; Alfonso, Belén F; Trobajo, Camino; Khainakov, Sergei; Garcia, Jose R; Garcia-Granda, Santiago; Castro, Germán R

    2012-01-01

    A portable powder-liquid high-corrosion-resistant reaction cell has been designed to follow in situ reactions by X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) techniques. The cell has been conceived to be mounted on the experimental stations for diffraction and absorption of the Spanish CRG SpLine-BM25 beamline at the European Synchrotron Radiation Facility. Powder reactants and/or products are kept at a fixed position in a vertical geometry in the X-ray pathway by a porous membrane, under forced liquid reflux circulation. Owing to the short pathway of the X-ray beam through the cell, XRD and XAS measurements can be carried out in transmission configuration/mode. In the case of the diffraction technique, data can be collected with either a point detector or a two-dimensional CCD detector, depending on specific experimental requirements in terms of space or time resolution. Crystallization processes, heterogeneous catalytic processes and several varieties of experiments can be followed by these techniques with this cell. Two experiments were carried out to demonstrate the cell feasibility: the phase transformations of layered titanium phosphates in boiling aqueous solutions of phosphoric acid, and the reaction of copper carbonate and L-isoleucine amino acid powders in boiling aqueous solution. In this last case the shrinking of the solid reactants and the formation of Cu(isoleucine)(2) is observed. The crystallization processes and several phase transitions have been observed during the experiments, as well as an unexpected reaction pathway. PMID:22186649

  10. Microwave peak absorption frequency of liquid

    NASA Astrophysics Data System (ADS)

    Han, Guangze; Chen, Mingdong

    2008-09-01

    Microwave-assisted extraction is a new effective method which has practical applications in many fields. Microwave heating is one of its physical mechanisms, and it also has the characteristic of selectivity. When the applied microwave frequency equals a certain absorption frequency of the material (or specific component), the material will intensively absorb microwave energy. This is also known as resonant absorption, and the frequency is called the peak absorption frequency which depends on the physical structure of the material. In this work, dynamic hydrogen bond energy was included in molecular activation energy; with the liquid cell model, the expression of interaction energy between dipolar molecules was derived. The rotational relaxation time was gotten from the Eyring viscosity formula. Then based on the relationship between dielectric dissipation coefficient and relaxation time, the expression of microwave peak absorption frequency as a function of the material physical structure, rotational inertia and electrical dipole moment of molecules was established. These theoretical formulas were applied to water and benzene, and the calculated results agree fairly well with the experimental data. This work can not only deepen the study of the interaction between microwave and material, but also provide a possible guide for the experiment of microwave-assisted extraction.

  11. High-intensity laser heating in liquids: Multiphoton absorption

    SciTech Connect

    Longtin, J.P.; Tien, C.L.

    1995-12-31

    At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in absorption and heating several orders of magnitude greater than classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for strong, controlled energy deposition in liquids without bulk plasma formation, shock waves, liquid ejection, etc., which is of interest for many laser-liquid applications, including laser desorption of liquid films, laser particle removal, and laser water removal from microdevices. This work develops a microscopically based model of the heating during multiphoton absorption in liquids. The dependence on pulse duration, intensity, wavelength, repetition rate, and liquid properties is discussed. Pure water exposed to 266 nm laser radiation is investigated, and a novel heating mechanism for water is proposed that uses multiple-wavelength laser pulses.

  12. Laser absorption phenomena in flowing gas devices

    NASA Technical Reports Server (NTRS)

    Chapman, P. K.; Otis, J. H.

    1976-01-01

    A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

  13. Effect of surface texture and liquid property on the liquid film flow on an inclined wall

    NASA Astrophysics Data System (ADS)

    Kato, M.; Iso, Y.; Huang, J.; Matsuno, S.

    2013-10-01

    Liquid film flow used for separation processes such as absorption is required to increase thegas-liquid interfacial area in order to improve the separation performance. Furthermore, the low liquid loading in absorption processes is effective for the economic performance. Liquid film with low liquid loading, however, breaks up to rivulet flow, as well as reduces its interfacial area between gas and liquid. The present study focuses on detailed descriptions of the transition phenomena betweenfilm flow andrivulet flow by varying not only liquid flow rate but also liquid properties, as well as how such phenomena are affected by wall surface texture treatments. Results obtained by Computational Fluid Dynamics (CFD) with the Volume of Fluid (VOF) model are validated by lab-scale experiments. The results of CFD show that a wavy surface is effective to prevent the liquid film break-up. Correlation equations for the wetted area ratio are derived as functions of the dimensionless parameters Weber number, Reynolds number, Froude number and the liquid contact angle.

  14. Liquid Flow in Biofilm Systems

    PubMed Central

    Stoodley, Paul; deBeer, Dirk; Lewandowski, Zbigniew

    1994-01-01

    A model biofilm consisting of Pseudomonas aeruginosa, Pseudomonas fluorescens, and Klebsiella pneumoniae was developed to study the relationships between structural heterogeneity and hydrodynamics. Local fluid velocity in the biofilm system was measured by a noninvasive method of particle image velocimetry, using confocal scanning laser microscopy. Velocity profiles were measured in conduit and porous medium reactors in the presence and absence of biofilm. Liquid flow was observed within biofilm channels; simultaneous imaging of the biofilm allowed the liquid velocity to be related to the physical structure of the biofilm. Images PMID:16349345

  15. Liquid cooled counter flow turbine bucket

    DOEpatents

    Dakin, James T.

    1982-09-21

    Means and a method are provided whereby liquid coolant flows radially outward through coolant passages in a liquid cooled turbine bucket under the influence of centrifugal force while in contact with countercurrently flowing coolant vapor such that liquid is entrained in the flow of vapor resulting in an increase in the wetted cooling area of the individual passages.

  16. Quantitative imaging of airway liquid absorption in cystic fibrosis.

    PubMed

    Locke, Landon W; Myerburg, Michael M; Markovetz, Matthew R; Parker, Robert S; Weber, Lawrence; Czachowski, Michael R; Harding, Thomas J; Brown, Stefanie L; Nero, Joseph A; Pilewski, Joseph M; Corcoran, Timothy E

    2014-09-01

    New measures are needed to rapidly assess emerging treatments for cystic fibrosis (CF) lung disease. Using an imaging approach, we evaluated the absorptive clearance of the radiolabeled small molecule probe diethylene triamine penta-acetic acid (DTPA) as an in vivo indicator of changes in airway liquid absorption. DTPA absorption and mucociliary clearance rates were measured in 21 patients with CF (12 adults and nine children) and nine adult controls using nuclear imaging. The effect of hypertonic saline on DTPA absorption was also studied. In addition, in vitro studies were conducted to identify the determinants of transepithelial DTPA absorption. CF patients had significantly increased rates of DTPA absorption compared with control subjects but had similar mucociliary clearance rates. Treatment with hypertonic saline resulted in a decrease in DTPA absorption and an increase in mucociliary clearance in 11 out of 11 adult CF patients compared with treatment with isotonic saline. In vitro studies revealed that ∼ 50% of DTPA absorption can be attributed to transepithelial fluid transport. Apically applied mucus impedes liquid and DTPA absorption. However, mucus effects become negligible in the presence of an osmotic stimulus. Functional imaging of DTPA absorption provides a quantifiable marker of immediate response to treatments that promote airway surface liquid hydration. PMID:24743971

  17. Absorption and emission in defective cholesteric liquid crystal cells

    NASA Astrophysics Data System (ADS)

    Gevorgyan, A. H.; Harutyunyan, M. Z.; Matinyan, G. K.; Oganesyan, K. B.; Rostovtsev, Yu V.; Kurizki, G.; Scully, M. O.

    2016-04-01

    We investigated peculiarities of absorption, emission and photonic density of states of a cholesteric liquid crystal with an isotropic defect layer inside. The influence of the defect layer position on absorption and emission in the system was studied. It was shown that for non-diffracting circularly polarized incident light absorption/emission is maximum if the defect is in the centre of the system; and for diffracting circularly polarized incident light absorption/emission is maximum if the defect is shifted from the centre of the system to its left border from where light is incident. We also investigated influence of the defect layer thickness and those parameters which characterize loss and gain on absorption and emission. The influence of anisotropic absorption in the cholesteric liquid crystal layer on photonic density states was investigated, too.

  18. Liquid Bismuth Propellant Flow Sensor

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Stanojev, B. J.; Korman, V.

    2007-01-01

    Quantifying the propellant mass flow rate in liquid bismuth-fed electric propulsion systems has two challenging facets. First, the flow sensors must be capable of providing a resolvable measurement at propellant mass flow rates on the order of 10 mg/see with and uncertainty of less that 5%. The second challenge has to do with the fact that the materials from which the flow sensors are fabricated must be capable of resisting any of the corrosive effects associated with the high-temperature propellant. The measurement itself is necessary in order to properly assess the performance (thrust efficiency, Isp) of thruster systems in the laboratory environment. The hotspot sensor[I] has been designed to provide the bismuth propellant mass flow rate measurement. In the hotspot sensor, a pulse of thermal energy (derived from a current pulse and associated joule heating) is applied near the inlet of the sensor. The flow is "tagged" with a thermal feature that is convected downstream by the flowing liquid metal. Downstream, a temperature measurement is performed to detect a "ripple" in the local temperature associated with the passing "hotspot" in the propellant. By measuring the time between the upstream generation and downstream detection of the thermal feature, the flow speed can be calculated using a "time of flight" analysis. In addition, the system can be calibrated by measuring the accumulated mass exiting the system as a-function of time and correlating this with the time it takes the hotspot to convect through the sensor. The primary advantage of this technique is that it doesn't depend on an absolute measurement of temperature but, instead, relies on the observation of thermal features. This makes the technique insensitive to other externally generated thermal fluctuations. In this paper, we describe experiments performed using the hotspot flow sensor aimed at quantifying the resolution of the sensor technology. Propellant is expelled onto an electronic scale to

  19. Liquid metal Flow Meter - Final Report

    SciTech Connect

    Andersen, C.; Hoogendoom, S.; Hudson, B.; Prince, J.; Teichert, K.; Wood, J.; Chase, K.

    2007-01-30

    Measuring the flow of liquid metal presents serious challenges. Current commercially-available flow meters use ultrasonic, electromagnetic, and other technologies to measure flow, but are inadequate for liquid metal flow measurement because of the high temperatures required by most liquid metals. As a result of the reactivity and high temperatures of most liquid metals, corrosion and leakage become very serious safety concerns. The purpose of this project is to develop a flow meter for Lockheed Martin that measures the flow rate of molten metal in a conduit.

  20. Terahertz absorption spectra and potential energy distribution of liquid crystals.

    PubMed

    Chen, Zezhang; Jiang, Yurong; Jiang, Lulu; Ma, Heng

    2016-01-15

    In this work, the terahertz (THz) absorption spectra of a set of nematic liquid crystals were studied using the density functional theories (DFT). An accurate assignment of the vibrational modes corresponding to absorption frequencies were performed using potential energy distribution (PED) in a frequency range of 0-3 THz. The impacts of different core structures on THz absorption spectra were discussed. The results indicate that scope of application must be considered in the LC-based THz device designing. This proposed work may give a useful suggestion on the design of novel liquid crystal material in THz wave. PMID:26476072

  1. Tuning the Carbon Dioxide Absorption in Amino Acid Ionic Liquids.

    PubMed

    Firaha, Dzmitry S; Kirchner, Barbara

    2016-07-01

    One of the possible solutions to prevent global climate change is the reduction of CO2 emissions, which is highly desired for the sustainable development of our society. In this work, the chemical absorption of carbon dioxide in amino acid ionic liquids was studied through first-principles methods. The use of readily accessible and biodegradable amino acids as building blocks for ionic liquids makes them highly promising replacements for the widely applied hazardous aqueous solutions of amines. A detailed insight into the reaction mechanism of the CO2 absorption was obtained through state-of-the-art theoretical methods. This allowed us to determine the reason for the specific CO2 capacities found experimentally. Moreover, we have also conducted a theoretical design of ionic liquids to provide valuable insights into the precise tuning of the energetic and kinetic parameters of the CO2 absorption. PMID:27214652

  2. Flow pattern and mass transfer characteristics of valve tray in absorption process

    NASA Astrophysics Data System (ADS)

    Nurkhamidah, Siti; Altway, Ali; Wulansari, Ayu Savitri; Khanifah, Evi Fitriyah

    2015-12-01

    The flow pattern characteristics of valve tray in absorption process which is expressed in pressure drop and the number of equivalent tank in series (N) has an important role to know the efficiency and performance of a process. This study has been done in the absorption column by using water and air as liquid and gas phase, respectively. To observe pressure drop and flow pattern in the column, flow rate of liquid and air has been variated. Flow pattern has been determined by using pulse method and using NaCl as tracer. The experiment results show that the column pressure drop is mainly influenced by the liquid height on the tray. When the water flow rate is high, liquid height on the tray is higher so that the column pressure drops increases. Flow pattern characteristic of fluid on valve tray is affected by water and air flowrates. For high water flow rate, the residence time distribution (RTD) curve is sharper and the number of N is greater and the flow pattern tends to a plug flow. However, the number of N decreases when the air flowrate increases. The liquid-side mass transfer coefficient (kLa') is shown by the following empirical relationship kLa' = 2,607QL0,202Qv0,456.

  3. Advances in gas-liquid flows 1990

    SciTech Connect

    Kim, J.M. . Nuclear Reactor Lab.); Rohatgi, U.S. ); Hashemi, A. )

    1990-01-01

    Gas-liquid two-phase flows commonly occur in nature and industrial applications. Rain, clouds, geysers, and waterfalls are examples of natural gas-liquid flow phenomena, whereas industrial applications can be found in nuclear reactors, steam generators, boilers, condensers, evaporators, fuel atomization, heat pipes, electronic equipment cooling, petroleum engineering, chemical process engineering, and many others. The household-variety phenomena such as garden sprinklers, shower, whirlpool bath, dripping faucet, boiling tea pot, and bubbling beer provide daily experience of gas-liquid flows. The papers presented in this volume reflect the variety and richness of gas-liquid two-phase flow and the increasing role it plays in modern technology. This volume contains papers dealing with some recent development in gas-liquid flow science and technology, covering basic gas-liquid flows, measurements and instrumentation, cavitation and flashing flows, countercurrent flow and flooding, flow in various components and geometries liquid metals and thermocapillary effects, heat transfer, nonlinear phenomena, instability, and other special and general topics related to gas-liquid flows.

  4. Characterization of hydrophobic nanoporous particle liquids for energy absorption

    NASA Astrophysics Data System (ADS)

    Hsu, Yi; Liu, Yingtao

    2016-04-01

    Recently, the development of hydrophobic nanoporous technologies has drawn increased attention, especially for the applications of energy absorption and impact protection. Although significant amount of research has been conducted to synthesis and characterize materials to protect structures from impact damage, the tradition methods focused on converting kinetic energy to other forms, such as heat and cell buckling. Due to their high energy absorption efficiency, hydrophobic nanoporous particle liquids (NPLs) are one of the most attractive impact mitigation materials. During impact, such particles directly trap liquid molecules inside the non-wetting surface of nanopores in the particles. The captured impact energy is simply stored temporarily and isolated from the original energy transmission path. In this paper we will investigate the energy absorption efficiency of combinations of silica nanoporous particles and with multiple liquids. Inorganic particles, such as nanoporous silica, are characterized using scanning electron microscopy. Small molecule promoters, such as methanol and ethanol, are introduced to the prepared NPLs. Their effects on the energy absorption efficiency are studied in this paper. NPLs are prepared by dispersing the studied materials in deionized water. Energy absorption efficiency of these liquids are experimentally characterized using an Instron mechanical testing frame and in-house develop stainless steel hydraulic cylinder system.

  5. Absorption and Oxidation of Nitrogen Oxide in Ionic Liquids.

    PubMed

    Kunov-Kruse, Andreas J; Thomassen, Peter L; Riisager, Anders; Mossin, Susanne; Fehrmann, Rasmus

    2016-08-01

    A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water. The nitric acid is absorbed in the ionic liquid up to approximately one mole HNO3 per mole of the ionic liquid due to the formation of hydrogen bonds. The nitric acid can be desorbed by heating, thereby regenerating the ionic liquid with excellent reproducibility. Here, time-resolved in-situ spectroscopic investigations of the reaction and products are presented. The procedure reveals a new vision for removing the pollutant NO by absorption into a non-volatile liquid and converting it into a useful bulk chemical, that is, HNO3 . PMID:27384885

  6. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, Robert F.

    1987-01-01

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs.

  7. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, R.F.

    1987-11-24

    A chemical absorptive separation of air in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent flow, reduced energy demand and reduced capital costs. 4 figs.

  8. Liquid-Flow Controller Responds To Pressure

    NASA Technical Reports Server (NTRS)

    Cox, George B., Jr.

    1990-01-01

    Mechanism controls flow of liquid in fuel-spraying head in combustion chamber responds nonlinearly to pressure of liquid. Shell of spraybar expands or contracts laterally as its internal pressure rises or falls, forcing collar down or up on entry tube. Area of window formed by slots in collar and entry tube thus increases or decreases. Drop in pressure through variable-area orifice increases much more with flow through orifice than does corresponding drop in pressure with flow through fixed-area orifice. In practical terms, lower pump pressure needed with variable orifice for given flow of liquid. Principle of operation applicable to spraying heads for other fluids.

  9. Modeling of Liquid Film along Absorber Cylinders in an Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Yamanaka, Tomofumi; Nagamoto, Wataru; Sugiyama, Takahide

    A two-dimensional liquid film model of LiBr solution falling along absorber cylinders has been studied to obtain boundary conditions for computing vapor flow in the absorber-evaporator of an absorption chiller. The model was established based on the assumptions that LiBr concentration and temperature profiles in the liquid film obey the third order polynomial expressions. It was indicated that mass flux and absorbed heat on the liquid surface can be calculated with simple numerical computations on the present analytical model. The overall heat transfer coefficient and total absorbed mass per second calculated with the present liquid film model was compared with experimental data for validation. The results calculated with the present model showed good agreement with the experimental data. Then, it was concluded the present model was useful enough for determining surface conditions on the LiBr liquid film around absorber cylinders.

  10. Electromagnetic flow rate meter. [for liquid metals

    NASA Technical Reports Server (NTRS)

    Banks, B. A. (Inventor)

    1974-01-01

    A liquid metal, whose flow rate is to be determined, is directed through a chamber made of electrically-insulating material on which there is impressed a magnetic field perpendicular to the direction of flow of the liquid metal. The magnetic field is made to increase in strength in a downstream direction of the flow of liquid metal. At least a pair of electrodes are disposed in the chamber traversely and perpendicular to the direction of flow and an ammeter is connected between the electrodes. Electrodes may be disposed in the top or the bottom of the chamber and each may be segmented. Oppositely disposed electrodes may be used with at least one dividing wall extending from each electrode to cause reversal of the direction of flow of the liquid metal. The magnetic field may be provided by electromagnets or permanent magnets such as shaded pole permanent magnets.

  11. Development of an Ionic-Liquid Absorption Heat Pump

    SciTech Connect

    Holcomb, Don

    2011-03-29

    Solar Fueled Products (SFP) is developing an innovative ionic-liquid absorption heat pump (ILAHP). The development of an ILAHP is extremely significant, as it could result in annual savings of more than 190 billion kW h of electrical energy and $19 billion. This absorption cooler uses about 75 percent less electricity than conventional cooling and heating units. The ILAHP also has significant environmental sustainability benefits, due to reduced CO2 emissions. Phase I established the feasibility and showed the economic viability of an ILAHP with these key accomplishments: • Used the breakthrough capabilities provided by ionic liquids which overcome the key difficulties of the common absorption coolers. • Showed that the theoretical thermodynamic performance of an ILAHP is similar to existing absorption-cooling systems. • Established that the half-effect absorption cycle reduces the peak generator temperature, improving collector efficiency and reducing collector area. • Component testing demonstrated that the most critical components, absorber and generator, operate well with conventional heat exchangers. • Showed the economic viability of an ILAHP. The significant energy savings, sustainability benefits, and economic viability are compelling reasons to continue the ILAHP development.

  12. Molecular absorption cryogenic cooler for liquid hydrogen propulsion systems

    NASA Technical Reports Server (NTRS)

    Klein, G. A.; Jones, J. A.

    1982-01-01

    A light weight, long life molecular absorption cryogenic cooler (MACC) system is described which can use low temperature waste heat to provide cooling for liquid hydrogen propellant tanks for interplanetary spacecraft. Detailed tradeoff studies were made to evaluate the refrigeration system component interactions in order to minimize the mass of the spacecraft cooler system. Based on this analysis a refrigerator system mass of 31 kg is required to provide the .48 watts of cooling required by a 2.3 meter diameter liquid hydrogen tank.

  13. Simultaneous heat and mass transfer in absorption of gases in laminar liquid films

    SciTech Connect

    Grossman, G

    1982-09-01

    A theoretical analysis of the combined heat and mass transfer process taking place in the absorption of a gas or vapor into a laminar liquid film is described. This type of process, which occurs in many gas-liquid systems, often releases only a small amount of heat, making the process almost isothermal. In some cases, however, the heat of absorption is significant and temperature variations cannot be ignored. One example, from which the present study originated, is in absorption heat pumps where mass transfer is produced specifically to generate a temperature change. The model analyzed describes a liquid film that flows over an inclined plane and has its free surface in contact with stagnant vapor. The absorption process at the surface creates nonuniform temperature and concentration profiles in the film, which develop until equilibrium between the liquid and vapor is achieved. The energy and diffusion equations are solved simultaneously to give the temperature and concentration variations at the interface and the wall. Two cases of interest are considered: constant-temperature and adiabatic walls. The Nusselt and Sherwood numbers are expressed in terms of the operating parameters, from which heat and mass transfer coefficients can be determined. The Nusselt and Sherwood numbers are found to depend on the Peclet and Lewis numbers as well as on the equilibrium characteristics of the working materials.

  14. Convection flows driven by laser heating of a liquid layer

    NASA Astrophysics Data System (ADS)

    Rivière, David; Selva, Bertrand; Chraibi, Hamza; Delabre, Ulysse; Delville, Jean-Pierre

    2016-02-01

    When a fluid is heated by the absorption of a continuous laser wave, the fluid density decreases in the heated area. This induces a pressure gradient that generates internal motion of the fluid. Due to mass conservation, convection eddies emerge in the sample. To investigate these laser-driven bulk flows at the microscopic scale, we built a setup to perform temperature measurements with a fluorescent-sensitive dye on the one hand, and measured the flow pattern at different beam powers, using a particle image velocimetry technique on the other hand. Temperature measurements were also used in numerical simulations in order to compare predictions to the experimental velocity profiles. The combination of our numerical and experimental approaches allows a detailed description of the convection flows induced by the absorption of light, which reveals a transition between a thin and a thick liquid layer regime. This supports the basis of optothermal approaches for microfluidic applications.

  15. High-throughput liquid-absorption preconcentrator sampling methods

    DOEpatents

    Zaromb, S.

    1994-07-12

    A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis. 12 figs.

  16. High-throughput liquid-absorption preconcentrator sampling methods

    DOEpatents

    Zaromb, Solomon

    1994-01-01

    A system for detecting trace concentrations of an analyte in air includes a preconcentrator for the analyte and an analyte detector. The preconcentrator includes an elongated tubular container comprising a wettable material. The wettable material is continuously wetted with an analyte-sorbing liquid which flows from one part of the container to a lower end. Sampled air flows through the container in contact with the wetted material with a swirling motion which results in efficient transfer of analyte vapors or aerosol particles to the sorbing liquid and preconcentration of traces of analyte in the liquid. The preconcentrated traces of analyte may be either detected within the container or removed therefrom for injection into a separate detection means or for subsequent analysis.

  17. A comparative flow visualization study of thermocapillary flow in drops in liquid-liquid systems

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rashidnia, N.

    1991-01-01

    Experiments are performed to visualize thermocapillary flow in drops in an immiscible host liquid. The host liquid used is silicone oil. Drops of three different liquids are used, viz, vegetable oil, water-methanol mixture anad pure methanol. Clear evidence of thermocapillary flow is seen in vegetable oil drops. For a mixture of water and methanol (approximately 50-50 by weight), natural convection is seen to dominate the flow outside the drop. Pure methanol drops exhibit thermocapillary flow, but dissolve in silicone oil. A small amount of water added to pure methanol significantly reduces the dissolution. Flow oscillations occur in this system for both isothermal and non-isothermal conditions.

  18. Geometry of thin liquid sheet flows

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Calfo, Frederick D.; Mcconley, Marc W.; Mcmaster, Matthew S.; Afjeh, Abdollah A.

    1994-01-01

    Incompresible, thin sheet flows have been of research interest for many years. Those studies were mainly concerned with the stability of the flow in a surrounding gas. Squire was the first to carry out a linear, invicid stability analysis of sheet flow in air and compare the results with experiment. Dombrowski and Fraser did an experimental study of the disintegration of sheet flows using several viscous liquids. They also detected the formulation of holes in their sheet flows. Hagerty and Shea carried out an inviscid stability analysis and calculated growth rates with experimental values. They compared their calculated growth rates with experimental values. Taylor studied extensively the stability of thin liquid sheets both theoretically and experimentally. He showed that thin sheets in a vacuum are stable. Brown experimentally investigated thin liquid sheet flows as a method of application of thin films. Clark and Dumbrowski carried out second-order stability analysis for invicid sheet flows. Lin introduced viscosity into the linear stability analysis of thin sheet flows in a vacuum. Mansour and Chigier conducted an experimental study of the breakup of a sheet flow surrounded by high-speed air. Lin et al. did a linear stability analysis that included viscosity and a surrounding gas. Rangel and Sirignano carried out both a linear and nonlinear invisid stability analysis that applies for any density ratio between the sheet liquid and the surrounding gas. Now there is renewed interest in sheet flows because of their possible application as low mass radiating surfaces. The objective of this study is to investigate the fluid dynamics of sheet flows that are of interest for a space radiator system. Analytical expressions that govern the sheet geometry are compared with experimental results. Since a space radiator will operate in a vacuum, the analysis does not include any drag force on the sheet flow.

  19. X-ray absorption spectroscopy of liquid surface

    NASA Astrophysics Data System (ADS)

    Watanabe, Iwao; Tanida, Hajime; Kawauchi, Sigehiro; Harada, Makoto; Nomura, Masaharu

    1997-09-01

    An apparatus has been constructed for x-ray absorption spectroscopy of elements at air/aqueous solution interface. Its surface sensitivity is gained from glancing incidence of synchrotron radiation under total reflection condition. The absorption is detected by total conversion He ion-yield method. This apparatus was operated at the beam line 7C of Photon Factory, where the incident photon beam comes from a sagittal focus double-crystal monochromator via a 70-cm-long bent mirror. The mirror focuses the beam vertically and changes the beam direction downward by 1 mrad to irradiate solution surface. The essential requirement of this technique, ripple-free liquid surface at accurate position, was attained by introducing a trough on a floating boat, continuous surface level monitoring, and an automatic Z-stage control. The x-ray absorption edge jump demonstrated that surface concentration of bromide ion follows the Langmuir type adsorption for tetraalkylammonuim bromide solution. By comparing the jump values for surface-active and -inactive bromide salt solutions, the detecting depth of the present technique was determined to be 8.8 nm. An extended x-ray absorption fine structure analysis of bromide ion segregated to the surface by stearyltrimethylammonium cation indicated that its solvation structure is different from that of bulk.

  20. Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

    DOEpatents

    Yeung, E.S.; Woodruff, S.D.

    1984-06-19

    A refractive index and absorption detector are disclosed for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded. 10 figs.

  1. Refractive index and absorption detector for liquid chromatography based on Fabry-Perot interferometry

    DOEpatents

    Yeung, Edward S.; Woodruff, Steven D.

    1984-06-19

    A refractive index and absorption detector for liquid chromatography. It is based in part on a Fabry-Perot interferometer and is used for the improved detection of refractive index and absorption. It includes a Fabry-Perot interferometer having a normally fixed first partially reflecting mirror and a movable second partially reflecting mirror. A chromatographic flow-cell is positioned between the mirrors along the optical axis of a monochromatic laser beam passing through the interferometer. A means for deriving information about the interference fringes coming out of the interferometer is used with a mini-computer to compute the refractive index of the specimen injected into the flow cell. The minicomputer continuously scans the interferometer for continuous refractive index readings and outputs the continuous results of the scans on a chart recorder. The absorption of the specimen can concurrently be scanned by including a second optical path for an excitation laser which will not interfere with the first laser, but will affect the specimen so that absorption properties can be detected. By first scanning for the refractive index of the specimen, and then immediately adding the excitation laser and subsequently scanning for the refractive index again, the absorption of the specimen can be computed and recorded.

  2. [The Diagnostics of Detonation Flow External Field Based on Multispectral Absorption Spectroscopy Technology].

    PubMed

    Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng

    2016-03-01

    Compared with traditional sampling-based sensing method, absorption spectroscopy technology is well suitable for detonation flow diagnostics, since it can provide with us fast response, nonintrusive, sensitive solution for situ measurements of multiple flow-field parameters. The temperature and concentration test results are the average values along the laser path with traditional absorption spectroscopy technology, while the boundary of detonation flow external field is unknown and it changes all the time during the detonation engine works, traditional absorption spectroscopy technology is no longer suitable for detonation diagnostics. The trend of line strength with temperature varies with different absorption lines. By increasing the number of absorption lines in the test path, more information of the non-uniform flow field can be obtained. In this paper, based on multispectral absorption technology, the reconstructed model of detonation flow external field distribution was established according to the simulation results of space-time conservation element and solution element method, and a diagnostic method of detonation flow external field was given. The model deviation and calculation error of the least squares method adopted were studied by simulation, and the maximum concentration and temperature calculation error was 20.1% and 3.2%, respectively. Four absorption lines of H2O were chosen and detonation flow was scanned at the same time. The detonation external flow testing system was set up for the valveless gas-liquid continuous pulse detonation engine with the diameter of 80 mm. Through scanning H2O absorption lines with a high frequency of 10 kHz, the on-line detection of detonation external flow was realized by direct absorption method combined with time-division multiplexing technology, and the reconstruction of dynamic temperature distribution was realized as well for the first time, both verifying the feasibility of the test method. The test results

  3. Liquid hydrogen flow problems in Kiwi reactors

    SciTech Connect

    Thurston, R.S.

    1992-09-01

    The Kiwi series of reactors were the first ones tested in the US Rover Program in the development of nuclear rocket engines for space propulsion. The early experiments with liquid hydrogen showed that parallel flow systems were prone to uneven flow distributions and violent fluctuations in pressure and flow that were capable of destroying a reactor core. Kiwi flow distribution problems were solved by using multiple feed lines into the nozzle cooling system and carefully balancing impedance among them. The violent pressure and flow fluctuations were eliminated after their cause was identified as resonance phenomena driven by the response to flow disturbances of heat transfer through a superheated hydrogen layer. Smooth flow operations were assured by rapidly bringing operating pressures beyond several times the critical pressure of hydrogen. After this initial rough start, solid core nuclear rocket engines successfully passed milestones of achievements during the remainder of the Rover program.

  4. Flow behavior in liquid molding

    NASA Technical Reports Server (NTRS)

    Hunston, D.; Phelan, F.; Parnas, R.

    1992-01-01

    The liquid molding (LM) process for manufacturing polymer composites with structural properties has the potential to significantly lower fabrication costs and increase production rates. LM includes both resin transfer molding and structural reaction injection molding. To achieve this potential, however, the underlying science base must be improved to facilitate effective process optimization and implementation of on-line process control. The National Institute of Standards and Technology (NIST) has a major program in LM that includes materials characterization, process simulation models, on-line process monitoring and control, and the fabrication of test specimens. The results of this program are applied to real parts through cooperative projects with industry. The key feature in the effort is a comprehensive and integrated approach to the processing science aspects of LM. This paper briefly outlines the NIST program and uses several examples to illustrate the work.

  5. Two-phase flow characteristics of liquid oxygen flow in low pressure liquid rocket engine

    NASA Astrophysics Data System (ADS)

    Cho, Namkyung; Kim, Seunghan; Kim, Youngmog; Jeong, Sangkwon; Jung, Jeheon

    2004-06-01

    In most cryogenic liquid rocket engines, liquid oxygen manifold and injector are not thermally insulated from room temperature environment for the purpose of reducing system complexity and weight. This feature of cryogenic liquid supply system results in the situation that liquid oxygen flow is vaporized especially in the vicinity of the manifold and the injector wall. The transient two-phase flow tendency is severe for low combustion pressure rocket engine without using turbo-pump. This paper focuses on the two-phase flow phenomena of liquid oxygen in low combustion pressure rocket engine. The KSR-III (Korea Sounding Rocket) engine test data is thoroughly analyzed to estimate the vapor fraction of liquid oxygen flow near the engine manifold and the injector. During the cold flow and the combustion tests of the KSR-III Engine, the static and dynamic pressures are measured at the engine inlet, the liquid oxygen manifold and the combustion chamber. The manifold outer wall and the inner wall temperatures are also measured. In this paper, we present the experimental investigation on the vapor generation, the vapor mass fraction, and the boiling characteristics of the liquid oxygen flow in the engine manifold and injector.

  6. Compartmentalized Droplets for Continuous Flow Liquid-Liquid Interface Catalysis.

    PubMed

    Zhang, Ming; Wei, Lijuan; Chen, Huan; Du, Zhiping; Binks, Bernard P; Yang, Hengquan

    2016-08-17

    To address the limitations of batch organic-aqueous biphasic catalysis, we develop a conceptually novel method termed Flow Pickering Emulsion, or FPE, to process biphasic reactions in a continuous flow fashion. This method involves the compartmentalization of bulk water into micron-sized droplets based on a water-in-oil Pickering emulsion, which are packed into a column reactor. The compartmentalized water droplets can confine water-soluble catalysts, thus "immobilizing" the catalyst in the column reactor, while the interstices between the droplets allow the organic (oil) phase to flow. Key fundamental principles underpinning this method such as the oil phase flow behavior, the stability of compartmentalized droplets and the confinement capability of these droplets toward water-soluble catalysts are experimentally and theoretically investigated. As a proof of this concept, case studies including a sulfuric acid-catalyzed addition reaction, a heteropolyacid-catalyzed ring opening reaction and an enzyme-catalyzed chiral reaction demonstrate the generality and versatility of the FPE method. Impressively, in addition to the excellent durability, the developed FPE reactions exhibit up to 10-fold reaction efficiency enhancement in comparison to the existing batch reactions, indicating a unique flow interface catalysis effect. This study opens up a new avenue to allow conventional biphasic catalysis reactions to access more sustainable and efficient flow chemistry using an innovative liquid-liquid interface protocol. PMID:27429173

  7. Gas-Liquid Flow in Pipelines

    SciTech Connect

    Thomas J. Hanratty

    2005-02-25

    A research program was carried out at the University of Illinois in which develops a scientific approach to gas-liquid flows that explains their macroscopic behavior in terms of small scale interactions. For simplicity, fully-developed flows in horizontal and near-horizontal pipes. The difficulty in dealing with these flows is that the phases can assume a variety of configurations. The specific goal was to develop a scientific understanding of transitions from one flow regime to another and a quantitative understanding of how the phases distribute for a give regime. These basic understandings are used to predict macroscopic quantities of interest, such as frictional pressure drop, liquid hold-up, entrainment in annular flow and frequency of slugging in slug flows. A number of scientific issues are addressed. Examples are the rate of atomization of a liquid film, the rate of deposition of drops, the behavior of particles in a turbulent field, the generation and growth of interfacial waves. The use of drag-reducing polymers that change macroscopic behavior by changing small scale interactions was explored.

  8. A study of thin liquid sheet flows

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Calfo, Frederick D.; Mcconley, Marc W.; Mcmaster, Matthew S.; Afjeh, Abdollah A.

    1993-01-01

    This study was a theoretical and experimental investigation of thin liquid sheet flows in vacuum. A sheet flow created by a narrow slit of width, W, coalesces to a point at a distance, L, as a result of surface tension forces acting at the sheet edges. As the flow coalesces, the fluid accumulates in the sheet edges. The observed triangular shape of the sheet agrees with the calculated triangular result. Experimental results for L/W as a function of Weber number, We, agree with the calculated result, L/W = the sq. root of 8We. The edge cross sectional shape is found to oscillate from elliptic to 'cigar' like to 'peanut' like and then back to elliptic in the flow direction. A theoretical one-dimensional model was developed that yielded only elliptic solutions for the edge cross section. At the points where the elliptic shapes occur, there is agreement between theory and experiment.

  9. Absorption measurements in liquid core waveguides using cavity ring-down spectroscopy.

    PubMed

    Bescherer, Klaus; Barnes, Jack A; Loock, Hans-Peter

    2013-05-01

    Short liquid core waveguides (LCWs) were included into a fiber-loop cavity ring-down absorption spectrometer to reduce the detection limit over, both, single pass absorption in a LCW and cavity-enhanced absorption using a conventional fiber-loop cavity. LCWs of 5 and 10 cm length were interfaced with a pressure-flow system and a multimode fiber-loop cavity using concave fiber lenses with matching numerical apertures and diameters. Two red dyes, Allura Red AC and Congo Red, were detected with a 532 nm pulsed laser at a 5 nM limit of detection in a detection volume of less than 1 μL, corresponding to a minimal detectable absorbance of less than 4 × 10(-4) cm(-1) and a minimal detectable change in absorption cross section, σ(min) = V(det) × ε × C(LOD), of about 14 μm(2) (Allura Red AC) and 37 μm(2) (Congo Red). PMID:23480430

  10. Ionic Liquid Development for Absorption Heat Pump Applications

    SciTech Connect

    MAERZKE, Katie; MOZURKEWICH, George; Abdelaziz, Omar; Gluesenkamp, Kyle R; Schneider, William F; Morrison, Doug; Maginn, Prof. Edward

    2014-01-01

    Ionic liquids (ILs) are a unique class of solvents with many potential applications, including absorption heating/cooling. Due to the large number of possible combinations of cations and anions, it is possible to tune the IL to obtain the required properties for the application of interest. Many ILs are very hydrophilic, while even the most hydrophobic ILs often absorb significant amounts of water. The presence of water in an IL can have a large effect on the system properties. For instance, a small amount of dissolved water often leads to a dramatic reduction in the viscosity of the mixture. Dissolved water also affects the ionic conductivity of ILs and alters the solvation power of ILs for both polar and non-polar solutes. Knowledge of the phase diagram of these IL/water mixtures therefore is essential when designing absorption heating systems. Measuring isotherms often requires time consuming and/or expensive experiments, and does not necessarily lead to a deeper understanding of the molecular level interactions responsible for water-IL interactions. In contrast, molecular simulations are relatively inexpensive to perform, allowing one to screen potential ILs for a given application. Simulation also provides a detailed picture of how water and a given IL interact, thereby providing insight into ways of designing an IL to have a desired water solubility. Toward this end, atomistic-level Monte Carlo (MC) simulations have been performed to predict isotherms for a variety of IL/water mixtures. The simulations predict that exchanging some of the IL cations with a small metal cation can lead to an increase in the hydrophilicity of the IL, which impacts the capacity of the fluid and the enthalpy of mixing. Molecular dynamics simulations, which unlike Monte Carlo simulations capture timedependent properties, were also carried out to estimate the relative viscosities of the solutions.

  11. Two-phase Flow Patterns in High Temperature Generator of Absorption Chiller / Heater

    NASA Astrophysics Data System (ADS)

    Furukawa, Masahiro; Kanuma, Hitoshi; Sekoguchi, Kotohiko; Takeishi, Masayuki

    There is a lack of information about vapor-liquid two-phase flow patterns determined using void signals in high temperature generator of absorption chiller/heater. Sensing void fraction has been hampered because lithium bromide aqueous solution of strong alkalinity is employed as working fluid at high temperature and high level of vacuum. New void sensor applicable to such difficult conditions was developed. The void Fractions at 48 locations in a high temperature generator were measured simultaneously in both cooling and heating operations. Analysis of void signals detected reveals that the most violent boiling occurs at the upper part of rear plate of combustion chamber and the first line of vertical tubes located in the flue. The flow patterns are strongly affected by the system pressure difference between the cooling and heating operations: there appear bubbly, slug and froth flows in the cooling operation, but only bubbly flow in the heating operation.

  12. Turbulent diamagnetism in flowing liquid sodium.

    PubMed

    Spence, E J; Nornberg, M D; Jacobson, C M; Parada, C A; Taylor, N Z; Kendrick, R D; Forest, C B

    2007-04-20

    The nature of Ohm's law is examined in a turbulent flow of liquid sodium. A magnetic field is applied to the flowing sodium, and the resulting magnetic field is measured. The mean velocity field of the sodium is also measured in an identical-scale water model of the experiment. These two fields are used to determine the terms in Ohm's law, indicating the presence of currents driven by a turbulent electromotive force. These currents result in a diamagnetic effect, generating magnetic field in opposition to the dominant fields of the experiment. The magnitude of the fluctuation-driven magnetic field is comparable to that of the field induced by the sodium's mean flow. PMID:17501423

  13. An automatic countercurrent liquid-liquid micro-extraction system coupled with atomic absorption spectrometry for metal determination.

    PubMed

    Mitani, Constantina; Anthemidis, Aristidis N

    2015-02-01

    A novel and versatile automatic sequential injection countercurrent liquid-liquid microextraction (SI-CC-LLME) system coupled with atomic absorption spectrometry (FAAS) is presented for metal determination. The extraction procedure was based on the countercurrent flow of aqueous and organic phases which takes place into a newly designed lab made microextraction chamber. A noteworthy feature of the extraction chamber is that it can be utilized for organic solvents heavier or lighter than water. The proposed method was successfully demonstrated for on-line lead determination and applied in environmental water samples using an amount of 120 μL of chloroform as extractant and ammonium diethyldithiophosphate as chelating reagent. The effect of the major experimental parameters including the volume of extractant, as well as the flow rate of aqueous and organic phases were studied and optimized. Under the optimum conditions for 6 mL sample consumption an enhancement factor of 130 was obtained. The detection limit was 1.5 μg L(-1) and the precision of the method, expressed as relative standard deviation (RSD) was 2.7% at 40.0 μg L(-1) Pb(II) concentration level. The proposed method was evaluated by analyzing certified reference materials and spiked environmental water samples. PMID:25435230

  14. Generation of volatile copper species after in situ ionic liquid formation dispersive liquid-liquid microextraction prior to atomic absorption spectrometric detection.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka; Matusiewicz, Henryk

    2014-11-01

    The new procedure using in situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with generation of volatile species prior to electrothermal atomic absorption spectrometry (ET AAS) for the determination of copper in soil samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination. Under optimal conditions, the extraction in 10 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) (as the extraction solvent) was conducted. The ionic liquid served as two-task reagent: the efficient extractant and enhancement substance for generation step. The chemical generation of volatile species was performed by reduction of acidified copper solution (HCl 0.8 mol L(-1)) with NaBH4 (1.5%). Some essential parameters of the chemical generation such as NaBH4 and HCl concentrations, the kind and concentration of ionic liquid, carrier gas (Ar) flow rate, reaction and trapping time as well as pyrolysis and atomization temperatures were studied. For photogeneration the effect of the parameters such as the kind and concentration of low molecular weight organic acids and ionic liquid, carrier gas (Ar) flow rate, UV irradiation and ultrasonication time on the analytical signals were studied. The detection limit was found as 1.8 ng mL(-1) and the relative standard deviation (RSD) for seven replicate measurements of 100 µg mL(-1) in sample solution was 7%. The accuracy of the proposed method was evaluated by analysis of the certified reference materials. The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the soil and sediment samples. PMID:25127592

  15. Absorption Filter Based Optical Diagnostics in High Speed Flows

    NASA Technical Reports Server (NTRS)

    Samimy, Mo; Elliott, Gregory; Arnette, Stephen

    1996-01-01

    Two major regimes where laser light scattered by molecules or particles in a flow contains significant information about the flow are Mie scattering and Rayleigh scattering. Mie scattering is used to obtain only velocity information, while Rayleigh scattering can be used to measure both the velocity and the thermodynamic properties of the flow. Now, recently introduced (1990, 1991) absorption filter based diagnostic techniques have started a new era in flow visualization, simultaneous velocity and thermodynamic measurements, and planar velocity measurements. Using a filtered planar velocimetry (FPV) technique, we have modified the optically thick iodine filter profile of Miles, et al., and used it in the pressure-broaden regime which accommodates measurements in a wide range of velocity applications. Measuring velocity and thermodynamic properties simultaneously, using absorption filtered based Rayleigh scattering, involves not only the measurement of the Doppler shift, but also the spectral profile of the Rayleigh scattering signal. Using multiple observation angles, simultaneous measurement of one component velocity and thermodynamic properties in a supersonic jet were measured. Presently, the technique is being extended for simultaneous measurements of all three components of velocity and thermodynamic properties.

  16. Origin of Surface-Driven Passive Liquid Flows.

    PubMed

    Yd, Sumith; Maroo, Shalabh C

    2016-08-30

    Passive liquid flow occurs in nature in the transport of water up tall trees and is desired for high-heat flux removal in thermal management devices. Typically, liquid-vapor surface tension is used to generate passive flows (e.g., capillary and Marangoni flows). In this work, we perform a fundamental molecular study on passive liquid flow driven by the solid-liquid surface tension force. Such surface tension values are first estimated by placing a liquid film over the surface and simulating various surface temperatures, followed by which simulations are performed by differential heating of the liquid film over the surface. Very strong passive liquid flows are obtained that lead to steady-state, continuous, and high-heat flux removal close to the maximum theoretical limit, as predicted by the kinetic theory of evaporation. Nondimensional empirical relations are developed for surface tension gradient, flow velocity, and evaporation rate. PMID:27483012

  17. Stability of Thin Liquid Sheet Flows

    NASA Technical Reports Server (NTRS)

    McConley, Marc W.; Chubb, Donald L.; McMaster, Matthew S.; Afjeh, Abdollah A.

    1997-01-01

    A two-dimensional, linear stability analysis of a thin nonplanar liquid sheet flow in vacuum is carried out. A sheet flow created by a narrow slit of W and tau attains a nonplanar cross section as a consequence of cylinders forming on the sheet edge under the influence of surface tension forces. The region where these edge cylinders join the sheet is one of high curvature, and this is found to be the location where instability is most likely to occur. The sheet flow is found to be unstable, but with low growth rates for symmetric wave disturbances and high growth rates for antisymmetric disturbances. By combining the symmetric and antisymmetric disturbance modes, a wide range of stability characteristics is obtained. The product of unstable growth rate and flow time is proportional to the width-to-thickness ratio of the sift generating the sheet Three-dimensional effects can alter these results, particularly when the sheet length-to-width ratio is not much greater than unity.

  18. Flow Induced Electrification of Liquid Insulated Systems.

    NASA Astrophysics Data System (ADS)

    Washabaugh, Andrew Patrick

    1995-01-01

    The transport or motion of semi-insulating liquids has led to flow induced static electrification and catastrophic failures in several industries. While techniques for reducing the hazard have been developed, the roles of seemingly important parameters are poorly understood. The objective of this thesis was to measure and understand the fundamental parameters of the flow electrification process that, together with the laws of electroquasistatics and physicochemical hydrodynamics, can be used to predict the performance of complex flow systems, with particular attention to transformer applications. A rotating cylindrical electrode apparatus, which provided cylindrical Couette flow, was used to simulate flow electrification in an electric power transformer. The apparatus had Shell Diala A transformer oil filling the annulus between coaxial cylindrical stainless steel electrodes that were either bare metal, or covered by a thin copper sheet and/or EHV-Weidmann HiVal pressboard insulation. Extensive experiments characterized the time transient and steady state behavior of the electrification through measurements of the volume charge density, the terminal voltage, and the terminal current as the system was driven out of equilibrium by changes in the flow rate (inner cylinder rotation rates of 100-1400 rpm, Reynolds numbers of 5 times 10^3-5 times 10^5), temperature (15-70 ^circ), insulation moisture content (0.5-20 ppm in the oil), applied voltage (0-2 kV DC), and concentration of the non-ionizable anti-static additive 1,2,3 benzotriazole (BTA, 0-60 ppm). Generally, the electrification increased with flow rate and temperature but the BTA appeared to cause competing effects: it decreased the volume charge density on the liquid side of the interface (by a factor of 4), which reduces the electrification, but also decreased the oil conductivity (by a factor of 10), which enhances the electrification. A critical oil BTA concentration of 5 -8 ppm minimized the electrification

  19. Flow of liquids in surface grooves

    SciTech Connect

    Rye, R.R.; Yost, F.G.; Mann, J.A. Jr.

    1996-01-24

    We have obtained detailed capillary kinetic data for flow of a series of alcohols with various surface tension to viscosity ratios, {gamma}/{mu}, spreading in open V-shaped grooves cut in Cu with three different groove angles. Two theoretical models which assume Poiseuille flow and static advancing contact angles were tested against the experimental data. One is a detailed hydrodynamic model with the basic driving force resulting from the pressure drop across a curved interface. The second depends on the total interfacial energy change, independent of the shape of the liquid interface. Both agree with the experimental data. Both predict numerical values in general agreement with experiment and with each other. In the threshold region where the transition occurs between filled and empty regions of the groove, the liquid height decreases linearly with distance, within experimental limitations, and forms an angle which roughly scales as the contact angle for a significant fraction of the threshold region. On the basis of the present detailed experimental data for both kinetics and threshold profile, the differences between experiment and theory and between the theoretical models are insufficient to allow a clear choice between the models. 20 refs., 11 figs., 3 tabs.

  20. IHT: Tools for Computing Insolation Absorption by Particle Laden Flows

    SciTech Connect

    Grout, R. W.

    2013-10-01

    This report describes IHT, a toolkit for computing radiative heat exchange between particles. Well suited for insolation absorption computations, it is also has potential applications in combustion (sooting flames), biomass gasification processes and similar processes. The algorithm is based on the 'Photon Monte Carlo' approach and implemented in a library that can be interfaced with a variety of computational fluid dynamics codes to analyze radiative heat transfer in particle-laden flows. The emphasis in this report is on the data structures and organization of IHT for developers seeking to use the IHT toolkit to add Photon Monte Carlo capabilities to their own codes.

  1. Characteristics of Liquid Flow Induced by Atmospheric Pressure DC Glow Discharge with Liquid Electrode

    NASA Astrophysics Data System (ADS)

    Tochikubo, Fumiyoshi; Aoki, Takuya; Shirai, Naoki; Uchida, Satoshi

    2015-09-01

    In the application of atmospheric-pressure discharges in contact with liquid, primary reactions are initiated between radicals and liquid molecules at plasma-liquid interface. Since the diffusion in the liquid is very slow, some convective flow is necessary to exchange the chemicals at the plasma-liquid interface for the efficient reactions. In our previous work, we found the appearance of specific downward flow in the liquid just below the dc glow discharge in contact with liquid. This downflow will be effective for exchanging the chemicals at plasma-liquid interface. In this work, we investigated the characteristics of liquid flow induced by atmospheric-pressure dc glow discharge with liquid electrode in detail; the influence of voltage polarity, current amplitude, liquid conductivity, the electrode arrangement, and so on. The spatiotemporal development of liquid flow was visualized by schlieren method, and the temperature distribution was measured using temperature-sensitive liquid crystal particles dispersed in the liquid. The liquid-flow characteristics was reproduced by a fluid simulation considering a downward driving force at liquid surface from plasma. The candidate of the driving force will be the momentum transfer of charged species at the liquid surface. This work is partly supported by JSPS KAKENHI Grant Number 15H03584.

  2. Fluid flow from a low to a higher density liquid

    NASA Astrophysics Data System (ADS)

    Weinberg, F.

    1984-12-01

    The penetration of liquid from a low density brine solution into a higher density solution below it has been measured as a function of vertical flow velocity and the density difference of the two solutions. The flow velocity was produced by a horizontal disc rotating in the low density liquid. The results show the penetration distance and penetration rate are dependent on flow velocity and in particular are very sensitive to small changes in the density difference between the two liquids. The observations are considered in relation to liquid penetration into dendritic arrays, and fluid flow in the pool of ingots and continuously cast steel billets, during solidification.

  3. Drop impact on flowing liquid films: asymmetric splashing

    NASA Astrophysics Data System (ADS)

    Ismail, Renad; Che, Zhizhao; Rotkovitz, Lauren; Adebayo, Idris; Matar, Omar

    2015-11-01

    The splashing of droplets on flowing liquid films is studied experimentally using high-speed photography. The flowing liquid films are generated on an inclined substrate. The flow rate of the liquid film, the inclination angle, and the droplet speed are controlled and their effects on the splashing process studied. Due to the flow in the liquid film and the oblique impact direction, the splashing process is asymmetric. The propagation of the asymmetric crown and the generation of secondary droplets on the rim of the crown are analysed through image processing. The results show that the flow in the liquid films significantly affects the propagation of the liquid crown and the generation of secondary droplets. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  4. Dataset used to improve liquid water absorption models in the microwave

    SciTech Connect

    Turner, David

    2015-12-14

    Two datasets, one a compilation of laboratory data and one a compilation from three field sites, are provided here. These datasets provide measurements of the real and imaginary refractive indices and absorption as a function of cloud temperature. These datasets were used in the development of the new liquid water absorption model that was published in Turner et al. 2015.

  5. Stability of erythrocyte suspensions layered on stationary and flowing liquids

    NASA Technical Reports Server (NTRS)

    Omenyi, S. N.; Rhodes, P. H.; Snyder, R. S.

    1982-01-01

    The apparent stability of erythrocyte suspensions layered on stationary and flowing Ficoll solutions was studied considering the effects of particle concentration, type and size, and the different flow rates of the particle suspensions and chamber liquid. The data from the flowing system were empirically fitted and, when extrapolated to zero chamber liquid flow rate, gave values comparable to the data from the stationary system, thus confirming the validity of the data and our approach to obtain that data.

  6. Heat Transfer Characteristics of Liquid-Gas Taylor Flows incorporating Microencapsulated Phase Change Materials

    NASA Astrophysics Data System (ADS)

    Howard, J. A.; Walsh, P. A.

    2014-07-01

    This paper presents an investigation on the heat transfer characteristics associated with liquid-gas Taylor flows in mini channels incorporating microencapsulated phase change materials (MPCM). Taylor flows have been shown to result in heat transfer enhancements due to the fluid recirculation experienced within liquid slugs which is attributable to the alternating liquid slug and gas bubble flow structure. Microencapsulated phase change materials (MPCM) also offer significant potential with increased thermal capacity due to the latent heat required to cause phase change. The primary aim of this work was to examine the overall heat transfer potential associated with combining these two novel liquid cooling technologies. By investigating the local heat transfer characteristics, the augmentation/degradation over single phase liquid cooling was quantified while examining the effects of dimensionless variables, including Reynolds number, liquid slug length and gas void fraction. An experimental test facility was developed which had a heated test section and allowed MPCM-air Taylor flows to be subjected to a constant heat flux boundary condition. Infrared thermography was used to record high resolution experimental wall temperature measurements and determine local heat transfer coefficients from the thermal entrance point. 30.2% mass particle concentration of the MPCM suspension fluid was examined as it provided the maximum latent heat for absorption. Results demonstrate a significant reduction in experimental wall temperatures associated with MPCM-air Taylor flows when compared with the Graetz solution for conventional single phase coolants. Total enhancement in the thermally developed region is observed to be a combination of the individual contributions due to recirculation within the liquid slugs and also absorption of latent heat. Overall, the study highlights the potential heat transfer enhancements that are attainable within heat exchange devices employing MPCM

  7. Synthesis of electroactive ionic liquids for flow battery applications

    SciTech Connect

    Anderson, Travis Mark; Ingersoll, David; Staiger, Chad; Pratt, Harry

    2015-09-01

    The present disclosure is directed to synthesizing metal ionic liquids with transition metal coordination cations, where such metal ionic liquids can be used in a flow battery. A cation of a metal ionic liquid includes a transition metal and a ligand coordinated to the transition metal.

  8. Slip flow of diverse liquids on robust superomniphobic surfaces.

    PubMed

    Wu, Yang; Cai, Meirong; Li, Zhenquan; Song, Xinwang; Wang, Hongyan; Pei, Xiaowei; Zhou, Feng

    2014-01-15

    Water slips exist over superhydrophobic solid surfaces, but the slip flow of diverse liquids on a single surface has not been deliberately studied to date. Here, we report the slip flow behavior of a variety of liquids with different surface tensions and viscosities on a robust omniphobic surface. This surface displayed a dramatic slippage effect and thus a high drag reduction efficiency of approximately 10-20% for all liquids, depending on both liquid viscosity and surface energy. The observed liquid slip was attributed to the surface dual micro/nanostructure and the low-surface-energy coating. PMID:24231078

  9. Analysis of gas absorption to a thin liquid film in the presence of a zero-order chemical reaction

    NASA Technical Reports Server (NTRS)

    Rajagopalan, S.; Rahman, M. M.

    1995-01-01

    The paper presents a detailed theoretical analysis of the process of gas absorption to a thin liquid film adjacent to a horizontal rotating disk. The film is formed by the impingement of a controlled liquid jet at the center of the disk and subsequent radial spreading of liquid along the disk. The chemical reaction between the gas and the liquid film can be expressed as a zero-order homogeneous reaction. The process was modeled by establishing equations for the conservation of mass, momentum, and species concentration and solving them analytically. A scaling analysis was used to determine dominant transport processes. Appropriate boundary conditions were used to solve these equations to develop expressions for the local concentration of gas across the thickness of the film and distributions of film height, bulk concentration, and Sherwood number along the radius of the disk. The partial differential equation for species concentration was solved using the separation of variables technique along with the Duhamel's theorem and the final analytical solution was expressed using confluent hypergeometric functions. Tables for eigenvalues and eigenfunctions are presented for a number of reaction rate constants. A parametric study was performed using Reynolds number, Ekman number, and dimensionless reaction rate as parameters. At all radial locations, Sherwood number increased with Reynolds number (flow rate) as well as Ekman number (rate of rotation). The enhancement of mass transfer due to chemical reaction was found to be small when compared to the case of no reaction (pure absorption), but the enhancement factor was very significant when compared to pure absorption in a stagnant liquid film. The zero-order reaction processes considered in the present investigation included the absorption of oxygen in aqueous alkaline solutions of sodiumdithionite and rhodium complex catalyzed carbonylation of methanol. Present analytical results were compared to previous theoretical

  10. Supported absorption of CO2 by tetrabutylphosphonium amino acid ionic liquids.

    PubMed

    Zhang, Jianmin; Zhang, Suojiang; Dong, Kun; Zhang, Yanqiang; Shen, Youqing; Lv, Xingmei

    2006-05-15

    A new type of "task specific ionic liquid", tetrabutylphosphonium amino acid [P(C4)4][AA], was synthesized by the reaction of tetrabutylphosphonium hydroxide [P(C4)4][OH] with amino acids, including glycine, L-alanine, L-beta-alanine, L-serine, and L-lysine. The liquids produced were characterized by NMR, IR spectroscopies, and elemental analysis, and their thermal decomposition temperature, glass transition temperature, electrical conductivity, density, and viscosity were recorded in detail. The [P(C4)4][AA] supported on porous silica gel effected fast and reversible CO2 absorption when compared with bubbling CO2 into the bulk of the ionic liquid. No changes in absorption capacity and kinetics were found after four cycles of absorption/desorption. The CO2 absorption capacity at equilibrium was 50 mol % of the ionic liquids. In the presence of water (1 wt %), the ionic liquids could absorb equimolar amounts of CO2. The CO2 absorption mechanisms of the ionic liquids with and without water were different. PMID:16528787

  11. Capillary-Driven Flow in Liquid Filaments Connecting Orthogonal Channels

    NASA Technical Reports Server (NTRS)

    Allen, Jeffrey S.

    2005-01-01

    Capillary phenomena plays an important role in the management of product water in PEM fuel cells because of the length scales associated with the porous layers and the gas flow channels. The distribution of liquid water within the network of gas flow channels can be dramatically altered by capillary flow. We experimentally demonstrate the rapid movement of significant volumes of liquid via capillarity through thin liquid films which connect orthogonal channels. The microfluidic experiments discussed provide a good benchmark against which the proper modeling of capillarity by computational models may be tested. The effect of surface wettability, as expressed through the contact angle, on capillary flow will also be discussed.

  12. Ab initio calculation of the electronic absorption spectrum of liquid water

    NASA Astrophysics Data System (ADS)

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-01

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  13. Ab initio calculation of the electronic absorption spectrum of liquid water

    SciTech Connect

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-28

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  14. Two-phase liquid-liquid flows generated by impinging liquid jets

    NASA Astrophysics Data System (ADS)

    Tsaoulidis, Dimitrios; Li, Qi; Angeli, Panagiota

    2015-11-01

    Two-phase flows in intensified small-scale systems find increasing applications in (bio)chemical analysis and synthesis, fuel cells, polymerisation, and separation processes (solvent extraction). Current nuclear spent fuel reprocessing separation technologies have been developed many decades ago and have not taken account recent advances on process intensification which can drive down plant size and economics. In this work, intensified impinging jets will be developed to create dispersions by bringing the two liquid phases into contact through opposing small channels. A systematic set of experiments has been undertaken, to investigate the hydrodynamic characteristics, to develop predictive models, and enable comparisons with other contactors. Drop size distribution and mixing intensity will be investigated for liquid-liquid mixtures as a function of various parameters using high speed imaging and conductivity probes.

  15. Liquid jet pumps for two-phase flows

    SciTech Connect

    Cunningham, R.G.

    1995-06-01

    Isothermal compression of a bubbly secondary fluid in a mixing-throat and diffuser is described by a one-dimensional flow model of a liquid-jet pump. Friction-loss coefficients used in the four equations may be determined experimentally, or taken from the literature. The model reduces to the liquid-jet gas compressor case if the secondary liquid is zero. Conversely, a zero secondary-gas flow reduces the liquid-jet gas and liquid (LJGL) model to that of the familiar liquid-jet liquid pump. A ``jet loss`` occurs in liquid-jet pumps if the nozzle tip is withdrawn from the entrance plane of the throat, and jet loss is included in the efficiency equations. Comparisons are made with published test data for liquid-jet liquid pumps and for liquid-jet gas compressors. The LJGL model is used to explore jet pump responses to two-phase secondary flows, nozzle-to-throat area ratio, and primary-jet velocity. The results are shown in terms of performance curves versus flow ratios. Predicted peak efficiencies are approximately 50 percent. Under sever operating conditions, LJGL pump performance curves exhibit maximum-flow ratios or cut-offs. Cut-offs occurs when two-phase secondary-flow steams attain sonic values at the entry of the mixing throat. A dimensionless number correlates flow-ratio cut-offs with pump geometry and operating conditions. Throat-entry choking of the secondary flow can be predicted, hence avoided, in designing jet pumps to hand two-phase fluids.

  16. Twin-peaks absorption spectra of excess electron in ionic liquids

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Kondoh, Takafumi; Yoshida, Yoichi; Takahashi, Kenji

    2014-07-01

    The solvated electron in room temperature ionic liquids (RTILs) has been the subject of several investigations and several reports exist on its nature and absorption spectrum. These studies concluded that the solvated electron exhibits an absorption spectrum peaking in the 1000-1400 nm region; a second absorption band peaking in the UV region has been assigned to the hole or dication radicals simultaneously formed in the system. Here we report on the fate of the excess electron in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, P14+/NTf2- using nanosecond pulse radiolysis. Scavenging experiments allowed us to record and disentangle the complex spectrum measured in P14+/NTf2-. We identified a bi-component absorption spectrum, due to the solvated electron, the absorption maxima located at 1080 nm and around 300 nm, as predicted by previous ab-initio molecular dynamics simulations for the dry excess electron. We also measured the spectra using different ionic liquids and confirmed the same feature of two absorption peaks. The present results have important implications for the characterization of solvated electrons in ionic liquids and better understanding of their structure and reactivity.

  17. Liquid water absorption and scattering effects in DOAS retrievals over oceans

    NASA Astrophysics Data System (ADS)

    Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

    2014-12-01

    Spectral effects of liquid water are present in absorption (differential optical absorption spectroscopy - DOAS) measurements above the ocean and, if insufficiently removed, may interfere with trace gas absorptions, leading to wrong results. Currently available literature cross sections of liquid water absorption are provided in coarser resolution than DOAS applications require, and vibrational Raman scattering (VRS) is mostly not considered, or is compensated for using simulated pseudo cross sections from radiative transfer modeling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS (Multi-AXis differential optical absorption spectroscopy) measurements of light penetrating very clear natural waters were performed, achieving average underwater light paths of up to 50 m. From these measurements, the retrieval of a correction spectrum (H2Ocorr) is presented, compensating simultaneously for insufficiencies in the liquid water absorption cross section and broad-banded VRS structures. Small-banded structures caused by VRS were found to be very efficiently compensated for by the intensity offset correction included in the DOAS fit. No interference between the H2Ocorr spectrum and phytoplankton absorption was found. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality, and performed better than using a liquid water cross section in combination with a simulated VRS spectrum. The decrease in the residual root mean square (rms) of the DOAS fit depends on the measurement's contamination with liquid water structures, and ranges from ≈ 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ocorr spectrum was found to prevent misfits of NO2 slant columns, especially for very low NO2 scenarios, and thus increases the reliability of the fit. In test fits on OMI satellite

  18. Liquid film flow in a fracture between two porous blocks

    SciTech Connect

    Dindoruk, B.; Firoozabadi, A. )

    1994-12-01

    Liquid film flow in a fracture between two porous bodies is mainly driven by pressure. The pressure drop across such a small distance could be significant. The flow of a liquid film is governed by the pressure drop across the fracture space, and therefore, understanding of liquid film flow in a single liquid bridge along a solid wall between two porous bodies is needed. The shape of the liquid bridge between the porous blocks is an unknown. The first step is to determine the shape of the free surface. Due to the nature of the problem, a boundary integral technique is found to provide the solution to the whole problem. Solutions are reported for a range of capillary numbers observed in cracked porous media. Pressure drop is correlated using a dimensionless capillary number group. Using analogy from the Darcy flow in porous media, a correlation for the equivalent Darcy permeability is developed.

  19. Simulation on Vapor Flow in the Absorber/Evaporator of an Absorption Chiller

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Nagamoto, Wataru; Sugiyama, Takahide

    Two-dimensional numerical computation methodology for vapor flow in the absorber/ evaporator in an absorption chiller has been suggested and the effect of pitch ratio of cylinders in the absorber/evaporator has been discussed. Pseudo-diffusion effects of surfactants added to lithium bromide solution flowing along cylinders in the absorber were considered into liquid film model suggested in the previous study. From the results, the present model was found to agree well with experimental data in a rather wide range of the pressure in the present system. The present model effectively reduces the computational load for vapor flow in the absorber/evaporator including 176 cylinders. Near the top and bottom walls of the absorber/evaporator, the high velocity regions were observed and the recirculating regions were also found to be formed just inside of the high velocity regions. This high velocity region is intensified with pitch-to-diameter ratio decrease because the vapor flow penetrating from the back side of the absorber increases for the pressure drop increase of front side of the absorber.

  20. Gas/liquid flow measurement using coriolis-based flow meters

    SciTech Connect

    Liu, K.T.; Nguyen, T.V.

    1991-07-09

    This patent describes a method of determining total mass flow rate and phase distribution of individual components in a flowing gas/liquid stream. It comprises flowing at least a first gas/liquid stream through a Coriolis-based flow meter, the first gas/liquid stream having a first known total mass flow rate and component phase distribution; obtaining a first apparent total mass flow rate output and a first apparent density output from the Coriolis- based mass flow meter; correlating the first known total mass flow rate and phase distribution with the first apparent mass flow rate output and the first apparent density output obtained from the Coriolis-based mass flow meter to determine a set of correlation equations; flowing a second gas/liquid stream through the Coriolis-based mass flow meter; obtaining a second apparent mass flow rate output and a second apparent density output from the Coriolis-based mass flow meter; calculating a total mass flow rate and a component phase distribution of the second gas/liquid stream based on the correlation equations and the second apparent mass flow rate output and the second apparent density output.

  1. highly selective amino acid salt solutions as absorption liquid for CO(2) capture in gas-liquid membrane contactors.

    PubMed

    Simons, Katja; Nijmeijer, Kitty; Mengers, Harro; Brilman, Wim; Wessling, Matthias

    2010-08-23

    The strong anthropogenic increase in the emission of CO(2) and the related environmental impact force the developments towards sustainability and carbon capture and storage (CCS). In the present work, we combine the high product yields and selectivities of CO(2) absorption processes with the advantages of membrane technology in a membrane contactor for the separation of CO(2) from CH(4) using amino acid salt solutions as competitive absorption liquid to alkanol amine solutions. Amino acids, such as sarcosine, have the same functionality as alkanol amines (e.g., monoethanolamine=MEA), but in contrast, they exhibit a better oxidative stability and resistance to degradation. In addition, they can be made nonvolatile by adding a salt functionality, which significantly reduces the liquid loss due to evaporation at elevated temperatures in the desorber. Membrane contactor experiments using CO(2)/CH(4) feed mixtures to evaluate the overall process performance, including a full absorption/desorption cycle show that even without a temperature difference between absorber and desorber, a CO(2)/CH(4) selectivity of over 70 can be easily achieved with the sarcosine salt solution as absorption liquid. This selectivity reaches values of 120 at a temperature difference between absorber and desorber of 35 degrees C, compared to a value of only 60 for MEA under the same conditions. Although CO(2) permeance values are somewhat lower than the values obtained for MEA, the results clearly show the potential of amino acid salt solutions as competitive absorption liquids for the energy efficient removal of CO(2). In addition, due to the low absorption of CH(4) in sarcosine compared to MEA, the loss of CH(4) is reduced and significantly higher CH(4) product yields can be obtained. PMID:20623726

  2. Enhanced light absorption in graphene via a liquid-crystalline optical diode

    NASA Astrophysics Data System (ADS)

    Pantazi, Aikaterini Iria; Yannopapas, Vassilios

    2016-09-01

    We demonstrate theoretically that light absorption in graphene can be boosted via a light-trapping mechanism based on a liquid-crystalline optical diode. The optical diode consists of twisted-nematic and nematic liquid-crystalline slabs. In particular, we show that, using a proper optical-diode setup, the absorption in a single graphene layer can be enhanced by a factor of four. By varying the pitch of the twisted-nematic liquid-crystalline slabs comprising the diode, one can tune the operating spectral region of the diode and thus enhance the absorption of graphene within a desired spectral window. Our calculations are based on Berreman's 4×4 method which treats anisotropic, isotropic and/ or inhomogeneous layered systems on equal footing.

  3. Phase-locked measurements of gas-liquid horizontal flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Matar, Omar; Markides, Christos

    2014-11-01

    A flow of gas and liquid in a horizontal pipe can be described in terms of various flow regimes, e.g. wavy stratified, annular or slug flow. These flow regimes appear at characteristic gas and liquid Reynolds numbers and feature unique wave phenomena. Wavy stratified flow is populated by low amplitude waves whereas annular flow contains high amplitude and long lived waves, so called disturbance waves, that play a key role in a liquid entrainment into the gas phase (droplets). In a slug flow regime, liquid-continuous regions travel at high speeds through a pipe separated by regions of stratified flow. We use a refractive index matched dynamic shadowgraphy technique using a high-speed camera mounted on a moving robotic linear rail to track the formation and development of features characteristic for the aforementioned flow regimes. We show that the wave dynamics become progressively more complex with increasing liquid and gas Reynolds numbers. Based on the shadowgraphy measurements we present, over a range of conditions: (i) phenomenological observations of the formation, and (ii) statistical data on the downstream velocity distribution of different classes of waves. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  4. CFD Analysis for Flow of Liquids in Coils

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, Tarun Kanti; Das, Sudip Kumar

    2016-04-01

    The effects of liquid flow rate, coil diameter, pseudo plasticity of the liquids on the frictional pressure drop for the flow through helical coils have been reported through experimental investigation. Numerical modeling is carried using Fluent 6.3 software to find its applicability in the flow system. The Computational Fluid Dynamics (CFD) simulations are carried out using laminar non-Newtonian pseudo plastic power law model for laminar flow and k-ɛ model for turbulent flow for water. Water and dilute solution of Sodium Carboxy Methyl Cellulose (SCMC) as a non-Newtonian pseudo plastic fluid used for the study. Both hexahedral and tetrahedral grids are used for this simulation. The CFD results show the very good agreement with the experimental values. The comparison of the non-Newtonian liquid flow and water are also reported.

  5. The use of infrared absorption to determine density of liquid hydrogen.

    NASA Technical Reports Server (NTRS)

    Unland, H. D.; Timmerhaus, K. D.; Kropschot, R. H.

    1972-01-01

    Experimental evaluation of the use of infrared absorption for determining the density of liquid hydrogen, and discussion of the feasibility of an airborne densitometer based on this concept. The results indicate that infrared absorption of liquid hydrogen is highly sensitive to the density of hydrogen, and, under the operating limitations of the equipment and experimental techniques used, the determined values proved to be repeatable to an accuracy of 2.7%. The desiderata and limitations of an in-flight density-determining device are outlined, and some of the feasibility problems are defined.

  6. Nonlinear absorption in ionic liquids with transition metallic atoms in the anion

    NASA Astrophysics Data System (ADS)

    Nóvoa-López, José A.; López Lago, Elena; Seijas, Julio A.; Pilar Vázquez-Tato, M.; Troncoso, Jacobo; de la Fuente, Raúl; Salgueiro, José R.; Michinel, Humberto

    2016-02-01

    Nonlinear absorption has been investigated by open aperture Z-scan in ionic liquids obtained by combination of 1-butyl-3-methyl-imidazolium cations with anions containing a transition metal (Co, Zn, Cu or Ni) and thiocyanate groups. The laser source was a Ti:Sapphire oscillator (80-fs pulses, λ = 810 nm, repetition rate of 80.75 MHz). All liquids present quite low heat capacities that favor the development of strong thermal effects. Thermal effects and nonlinear absorption make them potential materials for optical limiting purposes.

  7. Sewage sludge dewatering using flowing liquid metals

    DOEpatents

    Carlson, Larry W.

    1986-01-01

    A method and apparatus for reducing the moisture content of a moist sewage sludge having a moisture content of about 50% to 80% and formed of small cellular micro-organism bodies having internally confined water is provided. A hot liquid metal is circulated in a circulation loop and the moist sewage sludge is injected in the circulation loop under conditions of temperature and pressure such that the confined water vaporizes and ruptures the cellular bodies. The vapor produced, the dried sludge, and the liquid metal are then separated. Preferably, the moist sewage sludge is injected into the hot liquid metal adjacent the upstream side of a venturi which serves to thoroughly mix the hot liquid metal and the moist sewage sludge. The venturi and the drying zone after the venturi are preferably vertically oriented. The dried sewage sludge recovered is available as a fuel and is preferably used for heating the hot liquid metal.

  8. A model for absorption of solar radiation by mineral dust within liquid cloud drops

    NASA Astrophysics Data System (ADS)

    Zhang, Qing; Thompson, Jonathan E.

    2015-10-01

    Models of light scattering and absorption that consider the effect of insoluble inclusions present within liquid cloud droplets may assume the inclusion occupies random locations within the droplet. In certain cases, external forces can lead to certain orientations or alignments that are strongly preferred. Within this modeling study, we consider one such case in which an insoluble mineral dust inclusion (ρ=2.6 g/cm3) is placed within a liquid water drop (ρ=1.0 g/cm3). Such an instance mimics mineral dust aerosols being incorporated within cloud drops in Earth's atmosphere. Model results suggest super-micron mineral dust settles to the bottom of cloud droplets. However, Brownian motion largely randomizes the position of sub-micron mineral dust within the droplet. The inherent organization of the particles that result has important consequences for light absorption by mineral dust when present within a cloud drop. Modeled results suggest light absorption efficiency may be enhanced by as much as 4-6 fold for an isolated droplet experiencing direct solar illumination at solar zenith angles of <20°. For such an isolated droplet, the absorption efficiency enhancement falls rapidly with increasing solar zenith angle indicating a strong angle of incidence dependence. We also consider the more common case of droplets that contain dust inclusions deep within optically dense clouds. Absorption efficiency enhancements for these locales follow a dramatically different pattern compared to the optically isolated droplet due to the presence of diffuse rather than direct solar irradiation. In such cases, light absorption efficiency is decreased through including super-micron dust within water droplets. The study has important implications for modeling the absorption of sunlight by mineral dust aerosol within liquid water clouds. The angle of incidence dependence also reveals that experimental measurement of light absorption for cases in which particle alignment occurs may not

  9. Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

    USGS Publications Warehouse

    Messman, J.D.; Rains, T.C.

    1981-01-01

    A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

  10. Thaw flow control for liquid heat transport systems

    DOEpatents

    Kirpich, Aaron S.

    1989-01-01

    In a liquid metal heat transport system including a source of thaw heat for use in a space reactor power system, the thaw flow throttle or control comprises a fluid passage having forward and reverse flow sections and a partition having a plurality of bleed holes therein to enable fluid flow between the forward and reverse sections. The flow throttle is positioned in the system relatively far from the source of thaw heat.

  11. Large Flow Birefringence of Nematogenic Bent-Core Liquid Crystals

    SciTech Connect

    Bailey, C.; Fodor-Csorba, K; Verduzco, R; Gleeson, J; Sprunt, S; Jakli, A

    2009-01-01

    We have found that bent-core liquid crystalline materials show exceptionally large intrinsic flow birefringence in their isotropic liquid phase. This effect is more than 100 times larger than typical values measured for low molecular weight liquid crystals. The specific flow birefringence (i.e., normalized by the flow viscosity) is an order of magnitude larger than in both side-chain polymeric as well as low molecular weight liquid crystals. We propose that this large enhancement for bent-core compounds may be attributed to nanoscale smecticlike clusters that persist above the nematic-isotropic transition temperature, and shear align under shear flow; however, this mechanism has not yet been definitively confirmed.

  12. Confinement and flow of microscopic defects in layered liquids

    NASA Astrophysics Data System (ADS)

    Shojaei-Zadeh, Shahab

    The term layered liquid applies to a broad range of materials containing anisotropic molecules that arrange themselves in parallel stacks. Examples are concentrated surfactant solutions, block copolymers, bio-membranes, liquid crystalline polymers, and liquid crystals. Due to the solid-like nature of these materials, microscopic defects form when their parallel layer structure is disturbed by external forces, surface interactions, or geometrical confinement. Unlike in solid crystals, defects formed here can flow and we show that the presence of defects changes the flow characteristics of these materials. In this work, we first introduce three different methods for using surface treatments to control the size and ordering of a particular class of defects known as focal conics: within closed PDMS microchannels, on PDMS surfaces covered with nanoscale cracks, and within ordered microcavities formed in PDMS films. We then examine the flow behavior of these defects in microchannels, using both surface tension differences and pressure gradients to drive the flow. A microfluidic network is designed and developed to enable more precise control over the pressure driven flow. Driving flow within this microfluidic network enables simultaneous visualization of the defect texture evolution and measurement of the pressure gradient-flow rate relationship. Our measurements show that the flow properties of layered liquids under confinement are different from their bulk, possibly due to the interaction of defects with each other and with the flow itself.

  13. In-situ bioconjugation in stationary media and in liquid flow by femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Sajti, Csaba László; Petersen, Svea; Menéndez-Manjón, Ana; Barcikowski, Stephan

    2010-11-01

    In-situ functionalization of gold nanoparticles with fluorophore-tagged oligonucleotides is studied by comparing femtosecond laser ablation in stationary liquid and in biomolecule flow. Femtosecond laser pulses induce significant degradation to sensitive biomolecules when ablating gold in a stationary solution of oligonucleotides. Contrary, in-situ conjugation of nanoparticles in biomolecule flow considerably reduces the degree of degradation studied by gel electrophoresis and UV-Vis spectrometry. Ablating gold with 100 μJ femtosecond laser pulses DNA sequence does not degrade, while the degree of fluorophore tag degradation was 84% in stationary solution compared to 5% for 1 mL/min liquid flow. It is concluded that femtosecond laser-induced degradation of biomolecules is triggered by absorption of nanoparticle conjugates suspended in the colloid and not by ablation of the target. Quenching of nanoparticle size appears from 0.5 μM biomolecule concentration for 0.3 μg/s nanoparticle productivity indicating the successful surface functionalization. Finally, increasing the liquid flow rate from stationary to 450 mL/min enhances nanoparticle productivity from 0.2 μg/s to 1.5 μg/s, as increasing liquid flow allows removal of light absorbing nanoparticles from the ablation zone, avoiding attenuation of subsequent laser photons.

  14. Liquid water absorption and scattering effects in DOAS retrievals over oceans

    NASA Astrophysics Data System (ADS)

    Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

    2014-05-01

    It is well-known that spectral effects of liquid water are present in absorption (DOAS) measurements above the ocean and insufficiently removed liquid water structures may interfere with trace gas absorptions leading to wrong (sometimes even non-physical) results. Currently available literature cross-sections of liquid water absorption are provided in coarser resolution than hyperspectral DOAS applications require and Vibrational Raman Scattering (VRS) is mostly unconsidered or compensated for using simulated pseudo cross-sections from radiative transfer modelling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS measurements were performed into very clear natural waters achieving underwater light paths of up to 50 m. From these measurements, the retrieval of a residual (H2Ores) spectrum is presented compensating simultaneously for insufficiencies of the liquid water absorption cross-section and broad-banded VRS structures. Small-banded (Ring) structures caused by VRS were found to be very efficiently compensated for by the intensity offset (straylight) correction included in the DOAS fit. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality. This was not achieved using a liquid water cross-section in combination with a simulated VRS spectrum. Typical values of improvement depend on the measurement's contamination with liquid water structures and range from ≈ 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ores spectrum was found to prevent misfits of NO2 slant columns especially for very low NO2 scenarios and thus increase the reliability of the fit. In test fits on OMI satellite data, the H2Ores spectrum was found selectively above ocean surfaces where it leads to fit quality improvements of up to 6-18%.

  15. Investigation the flushing flow of liquid methane in Laval nozzle

    NASA Astrophysics Data System (ADS)

    Snigerev, B. A.; Tukmakov, A. L.; Tonkonog, V. G.

    2016-06-01

    Turbulent flushing flow of methane in Laval nozzles are investigated. To describe the motion of vapor-liquid mixture are used Favre averaged over the set of equations including the equations conservation of mass, momentum, and energy for a homogeneous mixture consisting from liquid and vapour phases. Numerical flow simulation based on cavitation approach using an additional transport equation for the volume fraction of the liquid phase. The study of the expiry of boiling methane at different degrees of underheating and the back pressures in the Laval nozzle are performed.

  16. Numerical investigation of droplet motion in rotating viscous liquid flow

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Tkachenko, A. S.; Usanina, A. S.

    2013-05-01

    The results of numerical investigation of the motion of a single droplet in a twisted flow of immiscible viscous liquid are presented. The motion trajectories of a droplet depending on its size, angular velocity of liquid rotation, and the physical parameters of the liquid and droplet have been determined. The values of the Reynolds, Bond, and Weber numbers along the droplet trajectory have been calculated. The effect of the Coriolis forces on the trajectory, velocity, and acceleration of the droplet in flow have been analyzed. The effect of the acceleration components of the droplet on the parameters of its motion is estimated. The numerical results are compared with experimental data.

  17. Supersonic Air Flow due to Solid-Liquid Impact

    NASA Astrophysics Data System (ADS)

    Gekle, Stephan; Peters, Ivo R.; Gordillo, José Manuel; van der Meer, Devaraj; Lohse, Detlef

    2010-01-01

    A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1m/s, this air jet attains supersonic speeds already when the cavity is slightly larger than 1 mm in diameter. The structure of the air flow closely resembles that of compressible flow through a nozzle—with the key difference that here the “nozzle” is a liquid cavity shrinking rapidly in time.

  18. Measurement of the Absorption and Scattering Properties of Turbid Liquid Foods Using Hyperspectral Imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reports on the development of a hyperspectral imaging technique for rapid determination of the absorption and scattering properties of turbid liquid foods over the visible and near-infrared region of 530-900 nm. A hyperspectral imaging system in line scanning mode was first tested and val...

  19. Effect of a falling gas-liquid absorption film temperature on entropy generation

    NASA Astrophysics Data System (ADS)

    Chermiti, Imen; Hidouri, Nejib; Brahim, Ammar Ben

    2013-08-01

    In this paper, an analytical study about the effect of a falling gas-liquid absorption film temperature on entropy generation is carried out. Entropy generation formulations due to viscous effects and mass transfer are derived. Results in terms of viscous, mass transfer and total irreversibilities are graphically presented and discussed.

  20. Efficiency of Absorption of Solar Radiation By Liquids Containing Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Astafyeva, L. G.; Pustovalov, V. K.

    2016-05-01

    We present the results of a comparative analysis of the optical properties of metallic nanoparticles that allows us to select their parameters for effective applications. The optical properties of several metallic (Ni, Ti, Pt, Zn, Mo, and Pd) monodisperse nanoparticles of radii 25 nm, 50 nm, and 75 nm were theoretically studied and analyzed in the spectral range 200-2500 nm. We studied the influence of the nanoparticle parameters (type of metal, radius and concentration of the nanoparticles, etc.) and the surrounding liquid (water) on the optical absorption cross section, scattering cross section, and extinction cross section for absorption, scattering, and extinction of radiation by the nanoparticles. We have established that titanium, nickel, and to a lesser extent molybdenum nanoparticles of radii ~75 nm can be used for efficient absorption and extinction of solar radiation by heterogeneous liquids.

  1. Multiphase flow of miscible liquids: jets and drops

    NASA Astrophysics Data System (ADS)

    Walker, Travis W.; Logia, Alison N.; Fuller, Gerald G.

    2015-05-01

    Drops and jets of liquids that are miscible with the surrounding bulk liquid are present in many processes from cleaning surfaces with the aid of liquid soaps to the creation of biocompatible implants for drug delivery. Although the interactions of immiscible drops and jets show similarities to miscible systems, the small, transient interfacial tension associated with miscible systems create distinct outcomes such as intricate droplet shapes and breakup resistant jets. Experiments have been conducted to understand several basic multiphase flow problems involving miscible liquids. Using high-speed imaging of the morphological evolution of the flows, we have been able to show that these processes are controlled by interfacial tensions. Further multiphase flows include investigating miscible jets, which allow the creation of fibers from inelastic materials that are otherwise difficult to process due to capillary breakup. This work shows that stabilization from the diminishing interfacial tensions of the miscible jets allows various elongated morphologies to be formed.

  2. Drop coalescence and liquid flow in a single Plateau border.

    PubMed

    Cohen, Alexandre; Fraysse, Nathalie; Raufaste, Christophe

    2015-05-01

    We report a comprehensive study of the flow of liquid triggered by injecting a droplet into a liquid foam microchannel, also called a Plateau border. This drop-injected experiment reveals an intricate dynamics for the liquid redistribution, with two contrasting regimes observed, ruled either by inertia or viscosity. We devoted a previous study [A. Cohen et al., Phys. Rev. Lett. 112, 218303 (2014)] to the inertial imbibition regime, unexpected at such small length scales. Here we report other features of interest of the drop-injected experiment, related to the coalescence of the droplet with the liquid microchannel, to both the inertial and viscous regimes, and to the occurrence of liquid flow through the soap films as well as effects of the interfacial rheology. The transition between the two regimes is investigated and qualitatively accounted for. The relevance of our results to liquid foam drainage is tackled by considering the flow of liquid at the nodes of the network of interconnected microchannels. Extensions of our study to liquid foams are discussed. PMID:26066250

  3. Drop coalescence and liquid flow in a single Plateau border

    NASA Astrophysics Data System (ADS)

    Cohen, Alexandre; Fraysse, Nathalie; Raufaste, Christophe

    2015-05-01

    We report a comprehensive study of the flow of liquid triggered by injecting a droplet into a liquid foam microchannel, also called a Plateau border. This drop-injected experiment reveals an intricate dynamics for the liquid redistribution, with two contrasting regimes observed, ruled either by inertia or viscosity. We devoted a previous study [A. Cohen et al., Phys. Rev. Lett. 112, 218303 (2014), 10.1103/PhysRevLett.112.218303] to the inertial imbibition regime, unexpected at such small length scales. Here we report other features of interest of the drop-injected experiment, related to the coalescence of the droplet with the liquid microchannel, to both the inertial and viscous regimes, and to the occurrence of liquid flow through the soap films as well as effects of the interfacial rheology. The transition between the two regimes is investigated and qualitatively accounted for. The relevance of our results to liquid foam drainage is tackled by considering the flow of liquid at the nodes of the network of interconnected microchannels. Extensions of our study to liquid foams are discussed.

  4. Contactless Inductive Bubble Detection in a Liquid Metal Flow.

    PubMed

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-01

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

  5. Contactless Inductive Bubble Detection in a Liquid Metal Flow

    PubMed Central

    Gundrum, Thomas; Büttner, Philipp; Dekdouk, Bachir; Peyton, Anthony; Wondrak, Thomas; Galindo, Vladimir; Eckert, Sven

    2016-01-01

    The detection of bubbles in liquid metals is important for many technical applications. The opaqueness and the high temperature of liquid metals set high demands on the measurement system. The high electrical conductivity of the liquid metal can be exploited for contactless methods based on electromagnetic induction. We will present a measurement system which consists of one excitation coil and a pickup coil system on the opposite sides of the pipe. With this sensor we were able to detect bubbles in a sodium flow inside a stainless steel pipe and bubbles in a column filled with a liquid Gallium alloy. PMID:26751444

  6. Emittance Measurements for a Thin Liquid Sheet Flow

    NASA Technical Reports Server (NTRS)

    Englehart, Amy N.; McConley, Marc W.; Chubb, Donald L.

    1996-01-01

    The Liquid Sheet Radiator (LSR) is an external flow radiator that uses a triangular-shaped flowing liquid sheet as the radiating surface. It has potentially much lower mass than solid wall radiators such as pumped loop and heat pipe radiators, along with being nearly immune to micrometeoroid penetration. The LSR has an added advantage of simplicity. Surface tension causes a thin (100-300 microns) liquid sheet to coalesce to a point, causing the sheet flow to have a triangular shape. Such a triangular sheet is desirable since it allows for simple collection of the flow at a single point. A major problem for all external flow radiators is the requirement that the working fluid be of very low (approx. 10(sup -8) torr) vapor pressure to keep evaporative losses low. As a result, working fluids are limited to certain oils (such as used in diffusion pumps) for low temperatures (300-400 K) and liquid metals for higher temperatures. Previous research on the LSR has been directed at understanding the fluid mechanics of thin sheet flows and assessing the stability of such flows, especially with regard to the formation of holes in the sheet. Taylor studied extensively the stability of thin liquid sheets both theoretically and experimentally. He showed that thin sheets in a vacuum are stable. The latest research has been directed at determining the emittance of thin sheet flows. The emittance was calculated from spectral transmittance data for the Dow Corning 705 silicone oil. By experimentally setting up a sheet flow, the emittance was also determined as a function of measurable quantities, most importantly, the temperature drop between the top of the sheet and the temperature at the coalescence point of the sheet. Temperature fluctuations upstream of the liquid sheet were a potential problem in the analysis and were investigated.

  7. Localized modes in optics of photonic liquid crystals with local anisotropy of absorption

    NASA Astrophysics Data System (ADS)

    Belyakov, V. A.; Semenov, S. V.

    2016-05-01

    The localized optical modes in spiral photonic liquid crystals are theoretically studied for the certainty at the example of chiral liquid crystals (CLCs) for the case of CLC with an anisotropic local absorption. The model adopted here (absence of dielectric interfaces in the structures under investigation) makes it possible to get rid of mixing of polarizations on the surfaces of the CLC layer and of the defect structure and to reduce the corresponding equations to only the equations for light with polarization diffracting in the CLC. The dispersion equations determining connection of the edge mode (EM) and defect mode (DM) frequencies with the CLC layer parameters (anisotropy of local absorption, CLC order parameter) and other parameters of the DMS are obtained. Analytic expressions for the transmission and reflection coefficients of CLC layer and DMS for the case of CLC with an anisotropic local absorption are presented and analyzed. It is shown that the CLC layers with locally anisotropic absorption reduce the EM and DM lifetimes (and increase the lasing threshold) in the way different from the case of CLC with an isotropic local absorption. Due to the Borrmann effect revealing of which is different at the opposite stop-band edges in the case of CLC layers with an anisotropic local absorption the EM life-times for the EM frequencies at the opposite stop-bands edges may be significantly different. The options of experimental observations of the theoretically revealed phenomena are briefly discussed.

  8. Effect of bile diversion on satiety and fat absorption from liquid and solid dietary sources

    SciTech Connect

    Doty, J.E.; Gu, Y.G.; Meyer, J.H.

    1988-12-01

    In previous studies, liquid fat has been used to determine the effect of bile diversion on fat absorption. Since protein digests, in addition to bile salts, are capable of solubilizing lipids, we hypothesized that fat incorporated in the protein-rich matrix of solid food would be less sensitive to bile diversion than fat ingested as an oil or liquid. Using (3H)glycerol triether as a nonabsorbable fat recovery marker, we determined how much (14C)triolein was absorbed from solid (chicken liver) and liquid (margarine) dietary sources. After a standard liquid/solid meal with either the chicken liver or margarine labeled, midintestinal chyme was collected for 6 hr, extracted, and counted for 14C and 3H activity. Zero, eighty, or one hundred percent of endogenous bile was diverted. Fat absorption from both chicken liver and margarine was nearly complete by midintestine with 0% diversion and was little affected by diversion of 80% of bile. Complete biliary diversion significantly decreased fat absorption from margarine (87.9 +/- 4.4 to 37.2 +/- 9.2%, P less than 0.05) but reduced (14C)triolein absorption from chicken liver less consistently and insignificantly (78.8 +/- 6.9 to 43.9 +/- 10.6%). These data indicate that fat absorption is not solely dependent on bile and support the hypothesis that fat ingested in a cellular matrix is less dependent on bile than liquid fat. Using these same animals but with the midintestinal cannulas plugged to expose the distal intestine to unabsorbed luminal nutrients, we also demonstrated that bile diversion of an initial meal reduced food consumption at a meal offered 3 hr later.

  9. Flow patterns in free liquid film caused by thermocapillary effect

    NASA Astrophysics Data System (ADS)

    Ueno, Ichiro; Fei, Linhao; Kowata, Yosuke; Kaneko, Toshihiro; Pettit, Donald

    2015-11-01

    The basic flow patterns realized in a thin free liquid film driven by the thermocapillary effect are focused. Spetial attention is paied to the effect of the volume ratio of the liquid film to the hole sustaining the film on the flow patterns. We prepare a thin liquid film of less than 0 . 5 mm in thickness in order to stably realize the film under normal gravity. Liquid has in general negative temperature coefficient of it surface tension; that is, the fluid is driven to the colder to hotter regions by the non-uniform surface-tension distribution. In the case of thin free liquid film, however, it is found that a unique flow pattern is induced. One of the present authors, DRP, carried out a series of experiments under microgravity condition in the International Space Station (ISS) in 2003. He prepared a ring made of metal, and formed a thin film of water inside the ring. Once he added a non-uniform temperature distribution to the film by placing a heated iron at one end of the ring, a net flow toward the heated iron was realized. In order to understand flow patterns, we focus on the flow structures of the thermocapillary convection in a cross section normal to the end walls as well as the surface temperature distributions.

  10. A study of vapor-liquid flow in porous media

    SciTech Connect

    Satik, Cengiz; Yortsos, Yanis C.

    1994-01-20

    We study the heat transfer-driven liquid-to-vapor phase change in single-component systems in porous media by using pore network models and flow visualization experiments. Experiments using glass micromodels were conducted. The flow visualization allowed us to define the rules for the numerical pore network model. A numerical pore network model is developed for vapor-liquid displacement where fluid flow, heat transfer and capillarity are included at the pore level. We examine the growth process at two different boundary conditions.

  11. Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings

    NASA Technical Reports Server (NTRS)

    Andres, Luis San

    1993-01-01

    A thermohydrodynamic analysis is presented and a computer code developed for prediction of the static and dynamic force response of hydrostatic journal bearings (HJB's), annular seals or damper bearing seals, and fixed arc pad bearings for cryogenic liquid applications. The study includes the most important flow characteristics found in cryogenic fluid film bearings such as flow turbulence, fluid inertia, liquid compressibility and thermal effects. The analysis and computational model devised allow the determination of the flow field in cryogenic fluid film bearings along with the dynamic force coefficients for rotor-bearing stability analysis.

  12. Liquid phase oxidation chemistry in continuous-flow microreactors.

    PubMed

    Gemoets, Hannes P L; Su, Yuanhai; Shang, Minjing; Hessel, Volker; Luque, Rafael; Noël, Timothy

    2016-01-01

    Continuous-flow liquid phase oxidation chemistry in microreactors receives a lot of attention as the reactor provides enhanced heat and mass transfer characteristics, safe use of hazardous oxidants, high interfacial areas, and scale-up potential. In this review, an up-to-date overview of both technological and chemical aspects of liquid phase oxidation chemistry in continuous-flow microreactors is given. A description of mass and heat transfer phenomena is provided and fundamental principles are deduced which can be used to make a judicious choice for a suitable reactor. In addition, the safety aspects of continuous-flow technology are discussed. Next, oxidation chemistry in flow is discussed, including the use of oxygen, hydrogen peroxide, ozone and other oxidants in flow. Finally, the scale-up potential for continuous-flow reactors is described. PMID:26203551

  13. Flow induced charging of liquids in reduced gravity

    SciTech Connect

    Pettit, D.R.

    1996-02-01

    Microgravity experiments on free fluid surfaces of large length scale could be subject to experimental artifact from flow induced charging. Under conditions favorable for flow induced charging, flowing liquids develop a static electrical charge which manifests itself as a force whose magnitude approaches that of surface tension force. Favorable conditions are: a non-conducting liquid, a small diameter non-conducting flow passage, a large flow volume, and a small separation distance between the fluid and another object. We present a method for calculating the magnitude of flow induced charging and scaling arguments so that potential problems can be determined and dealt with at the experimental design phase. A dimensionless ratio of charge force to surface tension force we call the Hula Number should be less than 0.5 to prevent artifact or unwanted fluid motion.

  14. Liquid rocket engine axial-flow turbopumps

    NASA Technical Reports Server (NTRS)

    Scheer, D. D.; Huppert, M. C.; Viteri, F.; Farquhar, J.; Keller, R. B., Jr. (Editor)

    1978-01-01

    The axial pump is considered in terms of the total turbopump assembly. Stage hydrodynamic design, pump rotor assembly, pump materials for liquid hydrogen applications, and safety factors as utilized in state of the art pumps are among the topics discussed. Axial pump applications are included.

  15. Retention/Diffusivity Studies in Free-Surface Flowing Liquid Lithium

    SciTech Connect

    R.A. Stubbers; G.H. Miley; M. Nieto; W. Olczak; D.N. Ruzic; A. Hassanein

    2004-12-14

    FLIRE was designed to measure the hydrogen and helium retention and diffusivity in a flowing stream of liquid lithium, and it has accomplished these goals. Retention coefficients for helium in the flowing liquid stream were 0.1-2% for flow speeds of 44 cm/s and implantation energies between 500 and 2000 eV. The energy dependence of retention is linear for the energy range considered, as expected, and the dependence of retention on flow velocity fits the expected square-root of flow speed dependence. Estimates of the helium diffusion coefficient in the flowing lithium stream were {approx} 4 x 10{sup -7} cm{sup 2}/s, and are independent of implantation energy. This value is much lower than expected, which could be due to several factors, such as mixing, bubble formation or surface film formation. In the case of hydrogen, long term retention and release mechanisms are of greatest importance, since this relates to tritium inventory in flowing lithium PFCs for fusion applications. The amount of hydride formation was measured for flowing lithium exposed to neutral deuterium gas. Thermal desorption spectroscopy (TDS) measurements indicate that the hydride concentration was between 0.1 and 0.2% over a wide range of pressures (6.5 x 10{sup -5} to 1 Torr). This result implies that the deuterium absorption rate is limited by the surface dissociation rate, since deuterium (hydrogen/tritium) is absorbed in its atomic form, not its molecular form.

  16. Effect of liquid products of semicoking on the absorption properties of arsenic-soda liquor

    SciTech Connect

    Tikhonov, V.S.; Anipko, S.N.; Buryak, V.I.; Fomin, B.M.

    1984-01-01

    The process gas obtained in the gasification of semicoke contains organic substances which, entering the arsenic-soda liquor in the process of removal of the sulfur from the gas, impairs its absorption properties. Thus, it is necessary to pretreat the gas to remove organic impurities, one of the methods being absorption. The absorbents may be organic liquids dissolving the gas impurities and having no effect on the absorption properties of the arsenic-soda liquor. The constant nature of the concentration of sulfide sulfur in the absorption liquor permits one to assume that the substances in semicoking middle oil still bottoms improve its redistribution in the hydroxythioarsenic salts with the formation of arsenates which react very slowly with the hydrogen sulfide, and thio-arsenates which do not react at all. A decrease in the sulfur content of the arsenic-soda solution was experienced.

  17. New Insights into CO2 Absorption Mechanisms with Amino-Acid Ionic Liquids.

    PubMed

    Yang, Qiwei; Wang, Zhiping; Bao, Zongbi; Zhang, Zhiguo; Yang, Yiwen; Ren, Qilong; Xing, Huabin; Dai, Sheng

    2016-04-21

    The last decade saw an explosion of interest in using amine-functionalized materials for CO2 capture and conversion, and it is of great importance to elucidate the relationship between the molecular structure of amine-functionalized materials and their CO2 capacity. In this work, based on a new quantitative analysis method for the CO2 absorption mechanism of amino-acid ionic liquids (ILs) and quantum chemical calculations, we show that the small difference in the local structure of amine groups in ILs could lead to much different CO2 absorption mechanisms, which provides an opportunity for achieving higher CO2 capacity by structure design. This work revealed that the actual CO2 absorption mechanism by amino-acid ILs goes beyond the apparent CO2 /amine stoichiometry; a rigid ring structure around the amine group in ILs creates a unique electrostatic environment that inhibits the deprotonation of carbamic acid and enables actually equimolar CO2 /amine absorption. PMID:27061812

  18. Instability due to interfacial tension in parallel liquid-liquid flow

    NASA Astrophysics Data System (ADS)

    Rodriguez, Oscar M. H.

    2016-06-01

    The frequent occurrence of multiphase flows in pipes has motivated a great research interest over the last decades. The particular case of liquid-liquid flow is commonly encountered in the petroleum industry, where a number of applications involve oil-water flow such as crude oil production in directional wells. However, it has not received the same attention when compared to gas-liquid flow. In addition, most of the available information has to do with flow in pipes. When it comes to flows in annular ducts the data are scanty. A general transition criterion has been recently proposed in order to obtain the stratified and core-annular flow-pattern transition boundaries in viscous oil-water flow. The proposed criterion was based on an one-dimensional two-fluid model of liquid-liquid two-phase flow. A stability analysis was carried out and interfacial tension is considered. A new destabilizing term arises, which is a function of the cross-section curvature of the interface. It is well accepted that interfacial tension favors the stable condition. However, the analysis of the new interfacial-tension term shows that it can actually destabilize the basic flow pattern, playing an important role in regions of extreme volumetric fractions. Such an interesting effect seems to be more pronounced in flows of viscous fluids and in annular-duct flow. The effect of interfacial tension is explored and the advantages of using a more complete model are discussed and illustrated through comparisons with experimental data from the literature. The evaluation of the effects of fluid viscosity and interfacial tension allows the correction and enhancement of transition models based essentially on data of pipe flow of low viscosity fluids.

  19. DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS

    SciTech Connect

    X. Wang; X. Sun; H. Zhao

    2011-09-01

    In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in

  20. Dual-plane ultrasound flow measurements in liquid metals

    NASA Astrophysics Data System (ADS)

    Büttner, Lars; Nauber, Richard; Burger, Markus; Räbiger, Dirk; Franke, Sven; Eckert, Sven; Czarske, Jürgen

    2013-05-01

    An ultrasound measurement system for dual-plane, two-component flow velocity measurements especially in opaque liquids is presented. Present-day techniques for measuring local flow structures in opaque liquids disclose considerable drawbacks concerning line-wise measurement of single ultrasound probes. For studying time-varying flow patterns, conventional ultrasound techniques are either limited by time-consuming mechanical traversing or by the sequential operation of single probes. The measurement system presented within this paper employs four transducer arrays with a total of 100 single elements which allows for flow mapping without mechanical traversing. A high frame rate of several 10 Hz has been achieved due to an efficient parallelization scheme using time-division multiplexing realized by a microcontroller-based electronic switching matrix. The functionality and capability of the measurement system are demonstrated on a liquid metal flow at room temperature inside a cube driven by a rotating magnetic field (RMF). For the first time, the primary and the secondary flow have been studied in detail and simultaneously using a configuration with two crossed measurement planes. The experimental data confirm predictions made by numeric simulation. After a sudden switching on of the RMF, inertial oscillations of the secondary flow were observed by means of a time-resolved measurement with a frame rate of 3.4 Hz. The experiments demonstrate that the presented measurement system is able to investigate complex and transient flow structures in opaque liquids. Due to its ability to study the temporal evolution of local flow structures, the measurement system could provide considerable progress for fluid dynamics research, in particular for applications in the food industry or liquid metal technologies.

  1. Confirmation of uncontrolled flow dynamics in clinical simulated multi-infusion setups using absorption spectral photometry

    NASA Astrophysics Data System (ADS)

    Timmerman, Anna M.; Riphagen, Brechtje; Klaessens, John H.; Verdaasdonk, Rudolf M.

    2010-02-01

    Multi-infusion systems are used frequently at intensive care units to administer several liquid therapeutic agents to patients simultaneously. By passively combining the separate infusion lines in one central line, the number of punctures needed to access the patient's body, is reduced. So far, the mutual influence between the different infusion lines is unknown. Although the flow properties of single infusion systems have been investigated extensively, only a few research groups have investigated the flow properties of multi-infusion systems. We showed in a previous study that applying multi-infusion can lead to fluctuations in syringe pump infusions, resulting in uncontrolled and inaccurate drug administration. This study presents a performance analysis of multi-infusion systems as used in the Neonatology Intensive Care Unit. The dynamics between multiple infusion lines in multi-infusion systems were investigated by simulation experiments of clinical conditions. A newly developed real-time spectral-photometric method was used for the quantitative determination of concentration and outflow volume using a deconvolution method of absorption spectra of mixed fluids. The effects for common clinical interventions were studied in detail. Results showed mutual influence between the different infusion lines following these interventions. This mutual influence led to significant volume fluctuations up to 50%. These deviations could result in clinically dangerous situations. A complete analysis of the multiinfusion system characteristics is recommended in further research to estimate both the presence and severity of potential risks in clinical use.

  2. UV-Vis Reflection-Absorption Spectroscopy at air-liquid interfaces.

    PubMed

    Rubia-Payá, Carlos; de Miguel, Gustavo; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

    2015-11-01

    UV-Visible Reflection-Absorption Spectroscopy (UVRAS) technique is reviewed with a general perspective on fundamental and applications. UVRAS is formally identical to IR Reflection-Absorption Spectroscopy (IRRAS), and therefore, the methodology developed for this IR technique can be applied in the UV-visible region. UVRAS can be applied to air-solid, air-liquid or liquid-liquid interfaces. This review focuses on the use of UVRAS for studying Langmuir monolayers. We introduce the theoretical framework for a successful understanding of the UVRAS data, and we illustrate the usage of this data treatment to a previous study from our group comprising an amphiphilic porphyrin. For ultrathin films with a thickness of few nm, UVRAS produces positive or negative bands when p-polarized radiation is used, depending on the incidence angle and the orientation of dipole absorption. UVRAS technique provides highly valuable information on tilt of chromophores at the air-liquid interface, and moreover allows the determination of optical parameters. We propose UVRAS as a powerful technique to investigate the in situ optical properties of Langmuir monolayers. PMID:26385430

  3. Physical Absorption Of CO2 in Protic and Aprotic Ionic Liquids: An Interaction Perspective.

    PubMed

    Izgorodina, Ekaterina I; Hodgson, Jennifer L; Weis, Derick C; Pas, Steven J; MacFarlane, Douglas R

    2015-09-01

    The physical absorption of CO2 by protic and aprotic ionic liquids such as 1-ethyl-3-methyl-imidazolium tetrafluoroborate was examined at the molecular level using symmetry adapted perturbation theory (SAPT) and density functional techniques through comparison of interaction energies of noncovalently bound complexes between the CO2 molecule and a series of ionic liquid ions and ion pairs. These energies were contrasted with those for complexes with model amines such as methylamine, dimethylamine, and trimethylamine. Detailed analysis of the five fundamental forces that are responsible for stabilization of the complexes is discussed. It was confirmed that the nature of the anion had a greater effect upon the physical interaction energy in non functionalized ionic liquids, with dispersion forces playing an important role in CO2 solubility. Hydrogen bonding with protic cations was shown to impart additional stability to the noncovalently bound CO2···IL complex through inductive forces. Two solvation models, the conductor-like polarizable continuum model (CPCM) and the universal solvation model (SMD), were used to estimate the impact of solvent effects on the CO2 binding. Both solvent models reduced interaction energies for all types of ions. These interaction energies appeared to favor imidazolium cations and carboxylic and sulfonic groups as well as bulky groups (e.g., NTf2) in anions for the physical absorption of CO2. The structure-reactivity relationships determined in this study may help in the optimization of the physical absorption process by means of ionic liquids. PMID:26267781

  4. Gas-Liquid Flows and Phase Separation

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    2004-01-01

    Common issues for space system designers include:Ability to Verify Performance in Normal Gravity prior to Deployment; System Stability; Phase Accumulation & Shedding; Phase Separation; Flow Distribution through Tees & Manifolds Boiling Crisis; Heat Transfer Coefficient; and Pressure Drop.The report concludes:Guidance similar to "A design that operates in a single phase is less complex than a design that has two-phase flow" is not always true considering the amount of effort spent on pressurizing, subcooling and phase separators to ensure single phase operation. While there is still much to learn about two-phase flow in reduced gravity, we have a good start. Focus now needs to be directed more towards system level problems .

  5. Counter current "emulsion flow" extractor for continuous liquid-liquid extraction from suspended solutions.

    PubMed

    Yanase, Nobuyuki; Naganawa, Hirochika; Nagano, Tetsushi; Noro, Junji

    2011-01-01

    A single current "emulsion flow" liquid-liquid extraction apparatus has a head with a number of holes from which micrometer-sized droplets of an aqueous phase spout into an organic phase to mix the two liquid phases. For practical use, however, a fatal problem can occur when particulate components in the aqueous phase plug the holes. In the present study, we have succeeded in solving the problem by applying a counter current-type emulsion flow extractor where micrometer-sized droplets of the organic phase are generated. PMID:21415518

  6. Experimental Analysis of the Effects of Vapor Flow Characteristics on Falling Film Absorption Rate in NH3-H2O Systems

    NASA Astrophysics Data System (ADS)

    Kang, Yong Tae; Fujita, Yasushi; Akisawa, Atsushi; Kashiwagi, Takao

    In this paper, experimental analysis was performed for ammonia-water falling film absorption process in a plate heat exchanger with enhanced surfaces such as offset strip fin. This paper examined the effect of vapor flow characteristics, inlet subcooling of the liquid flow and inlet concentration difference on heat and mass transfer performance. The inlet liquid concentration was kept constant at 0% while the inlet vapor concentration was varied from70. 36 to 77.31% It was found that before absorption started there was rectification process at the top of the test section by the inlet subcooling effect. Water desorption phenomenon was found near the bottom of test section. The lower inlet liquid temperature, the higher Nusselt and Sherwood numbers were obtained. NusseIt and Sherwood correlations were developed as functions of vapor Reynolds number ReV, inlet subcooling and inlet concentration difference with ±10% and ±5% error bands, respectively.

  7. Mass flow measurement of liquid cryogens using the triboelectric effect

    NASA Technical Reports Server (NTRS)

    Dechene, Ronald L.

    1986-01-01

    A cross correlator technique using triboelectric technology has been shown to be a feasible method to measure liquid flow rate for liquid nitrogen and JP4 jet fuel. This technology, invented and pioneered by Auburn International, Inc., is also expected to be suitable for use with all other insulating liquids and cryogens. The technology described is particularly well suited for cryogenic use, since the sensor is non-contacting and non-intrusive, and therefore, causes no additional pressure drop within the flow stream. Further development of the in-line sensor is required to produce a prototypical version for the test purposes under SSME fuel flow conditions. However, with the knowledge gained from this feasibility study, it is very likely that an acceptable sensor design for a full test bed evaluation could be produced.

  8. Design and synthesis of liquid crystals with controlled absorption properties in the midwave infrared region

    NASA Astrophysics Data System (ADS)

    Tripathi, Suvagata

    The infrared region of electromagnetic radiation is attractive for communication applications as the scattering is lower compared to that in the visible spectrum. Infrared lasers are widely used in bar-code scanners, laser rangefinders and topology mapping applications. Typically, the direction of a laser beam is altered by mechanically moving a mirror or a lens. But this process can impose severe limitations on critical performance parameters (longevity, precision, response time etc.) of the device. Thus, electro-optic control of the direction of the beam is highly desired. Commercial liquid crystals (LCs) are less than ideal for this purpose because they almost invariably have several absorption bands in the infrared region. For example, several absorption bands exist in the mid-infrared region (3-5 mum) due to common structure features found in LCs such as CH, CH 2, CH3 and CN. In the off-resonance regions, the baseline absorption coefficient can take very high value (up to alpha ~10/cm). This absorption loss becomes especially significant if the optical path is long. As the molecular vibration frequency (o) depends upon the spring constant (kappa) and the effective mass (m) of a diatomic group by the equation = √(kappa/m), replacement of hydrogen atoms in a molecule with heavier atoms can shift the absorptions to the far infrared region, thus making the midwave infrared region more transparent. Another strategy has been to develop high birefringence LCs so that lower liquid crystal cell gap can be used, thus minimizing the absorption loss due to the LC layer. But most of these materials have problems with UV stability. In the scope of this thesis, several strategies are investigated to mitigate the absorption loss in the midwave infrared region. The ultimate goal of this thesis is to develop LCs that will have both high birefringence and low absorption properties in the midwave-infrared region. Another goal of the thesis is to develop materials for

  9. About the statistical description of gas-liquid flows

    SciTech Connect

    Sanz, D.; Guido-Lavalle, G.; Carrica, P.

    1995-09-01

    Elements of the probabilistic geometry are used to derive the bubble coalescence term of the statistical description of gas liquid flows. It is shown that the Boltzmann`s hypothesis, that leads to the kinetic theory of dilute gases, is not appropriate for this kind of flows. The resulting integro-differential transport equation is numerically integrated to study the flow development in slender bubble columns. The solution remarkably predicts the transition from bubbly to slug flow pattern. Moreover, a bubbly bimodal size distribution is predicted, which has already been observed experimentally.

  10. Comparison of Glucosamine Absorption After Administration of Oral Liquid, Chewable, and Tablet Formulations to Dogs.

    PubMed

    Maxwell, Lara K; Regier, Penny; Achanta, Satyanarayana

    2016-01-01

    Glucosamine (GS) is commonly administered as a nutritional supplement to support joint function. Although many supplements are available, the effect of formulation on oral absorption in dogs is unknown. The purpose of this study was to determine the relative bioavailability of GS for liquid, chewable, and tablet formulations containing GS sulfate or hydrochloride and chondroitin sulfate. In a randomized cross-over design, supplements were administered daily for 8 days with a 1 wk washout period between treatments. Liquid or Tablet A was administered to four dogs, whereas Liquid or Tablet B was administered to four additional dogs. When nutraceutical exposure was normalized to the administered dose of GS free base, similar relative bioavailabilities were determined for all three formulations. However, the dose-normalized maximum plasma GS concentration was higher for the liquid supplement (5.5 ± 0.5 μg/mL) than for the two tablets (3.1 ± 0.6 and 2.1 ± 0.6 μg/mL, P < 0.001). Similarly, the time at which maximal plasma GS concentrations occurred was shorter for the liquid formulation (0.7 ± 0.5 hr) than for the two tablets (4.2 ± 0.6 and 5.0 ± 0.6 hr, P < 0.001). These data show that the formulation of joint supplements affects the oral absorption of GS in dogs. PMID:26808433

  11. Steering liquid metal flow in microchannels using low voltages.

    PubMed

    Tang, Shi-Yang; Lin, Yiliang; Joshipura, Ishan D; Khoshmanesh, Khashayar; Dickey, Michael D

    2015-10-01

    Liquid metals based on gallium, such as eutectic gallium indium (EGaIn) and Galinstan, have been integrated as static components in microfluidic systems for a wide range of applications including soft electrodes, pumps, and stretchable electronics. However, there is also a possibility to continuously pump liquid metal into microchannels to create shape reconfigurable metallic structures. Enabling this concept necessitates a simple method to control dynamically the path the metal takes through branched microchannels with multiple outlets. This paper demonstrates a novel method for controlling the directional flow of EGaIn liquid metal in complex microfluidic networks by simply applying a low voltage to the metal. According to the polarity of the voltage applied between the inlet and an outlet, two distinct mechanisms can occur. The voltage can lower the interfacial tension of the metal via electrocapillarity to facilitate the flow of the metal towards outlets containing counter electrodes. Alternatively, the voltage can drive surface oxidation of the metal to form a mechanical impediment that redirects the movement of the metal towards alternative pathways. Thus, the method can be employed like a 'valve' to direct the pathway chosen by the metal without mechanical moving parts. The paper elucidates the operating mechanisms of this valving system and demonstrates proof-of-concept control over the flow of liquid metal towards single or multiple directions simultaneously. This method provides a simple route to direct the flow of liquid metal for applications in microfluidics, optics, electronics, and microelectromechanical systems. PMID:26279150

  12. Impact of a single drop on a flowing liquid film.

    PubMed

    Gao, Xuan; Li, Ri

    2015-11-01

    The impact of a single liquid drop on a flowing liquid film is experimentally and theoretically studied. The drop impact produces a crownlike rising liquid sheet, which radially expands. Small droplets can be formed from the crown sheet, resulting in splash. The present study results in three major contributions. (1) A theoretical model is developed to predict the expansion of the crown base. The model with an introduced energy loss factor is shown to be in satisfactory agreement with our experimental observations of drop impact on both stationary and flowing films. The energy loss factor is correlated to the properties of the film and drop. (2) Analysis is conducted to derive an equation for evaluating the stretching rate of the rising crown sheet, which is the local gradient of the rising velocity at the top edge of the crown sheet. It shows that the highest stretching rate appears where the drop spreading flow is right opposite to the film flow, which helps explain why the same location is most probable for splash to take place. (3) A parameter as a function of modified Weber and Reynolds numbers is defined to predict splash and nonsplash of drop impact on flowing films. The two nondimensional numbers evaluate the competition of the two flows (drop and film) against viscosity and surface tension effects. A threshold value of the parameter is found for the occurrence of splash impact on flowing films. PMID:26651777

  13. Viscoelastic Flows in Simple Liquids Generated by Vibrating Nanostructures

    NASA Astrophysics Data System (ADS)

    Sader, John; Pelton, Matthew; Chakraborty, Debadi; Malachosky, Edward; Guyot-Sionnest, Philippe

    2014-11-01

    Newtonian fluid mechanics, in which the shear stress is proportional to the strain rate, is synonymous with the flow of simple liquids like water. We report the measurement and theoretical verification of non-Newtonian, viscoelastic flow phenomena produced by the high-frequency (>20 GHz) vibration of gold nanoparticles immersed in water-glycerol mixtures. The observed viscoelasticity is not due to molecular confinement, but is a bulk continuum effect arising from the short time scale of vibration. This represents the first direct mechanical measurement of the intrinsic viscoelastic properties of simple bulk liquids, and opens a new paradigm for understanding extremely high frequency fluid mechanics, nanoscale sensing technologies, and biophysical processes.

  14. Electromagnetically Sustained Liquid Metal Flow for Feedback Stabilization Studies

    NASA Astrophysics Data System (ADS)

    Mirhoseini, Seyyed Mohammad; Volpe, Francesco

    2015-11-01

    Liquid metal walls in fusion reactors, whether nearly static or rapidly flowing, will be subject to instabilities that will make them locally bulge, thus entering in contact with the plasma, or deplete, hence exposing the underlying solid substrate. To prevent this, research has begun at Columbia University to create liquid metal flows and demonstrate their stabilization by electromagnetic forces, adjusted in feedback with thickness measurements. Here we present initial results regarding the sustainment of a flow of Galinstan (a gallium, indium, tin alloy) by a special pump consisting of a ferromagnetic rotor, with permanent magnets mounted on it. The magnetic field is partly ``frozen'' in the liquid metal surrounding the rotor. Therefore, as the field rotates, the liquid metal rotates as well, although with a slip factor. This solution was preferred to conventional pumps, which would enter in electrical contact with the metal flow. The pump, 3D-printed at Columbia, allows to adjust the flow-velocity from few mm/s to several cm/s.

  15. Confinement effects on liquid-flow characteristics in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yasuoka, Haruka; Takahama, Ryo; Kaneda, Masayuki; Suga, Kazuhiko

    2015-12-01

    Liquid flow dynamics through the armchair (6 ,6 )-(160 ,160 ) carbon nanotubes (CNTs) is elucidated by molecular dynamics simulations. The liquid is modeled by nonpolar argon atoms to understand the fundamental flow physics. The velocity profiles and slip lengths are discussed considering the radial distributions of the fluid density by the presently proposed finite difference-based velocity fitting method. It is found that as the CNT diameter D increases, the slip length and the flow rate enhancement show three-step transitional profiles in the region of D ≤2.3 nm. The slip length and the flow rate stepwise increase at the first transition while they drop at the second and third transitions. The first transition corresponds to the structural change from the single-file chain to single-ring structures of the molecule cluster. The second and third transitions take place when the ring structure starts to develop another inner layer.

  16. Vortex shedding flowmeters for liquids at high flow velocities

    NASA Technical Reports Server (NTRS)

    Siegwarth, J. D.

    1985-01-01

    A number of vortex shedding flowmeter designs for flow measurements in liquid oxygen ducts on the space shuttle main engines have been tested in a high head water flow test facility. The results have shown that a vortex shedding element or vane spanning the duct can give a linear response to an average flow velocity of 46 m/s (150 ft/s) in a 1 1/2 inch nominal (41 mm actual) diameter duct while a vane partially spanning the duct can give a linear response to velocities exceeding 55 m/s (180 ft/s). The maximum pressure drops across the flow sensing elements extrapolate to less than 0.7 MPa (100 psi) at 56 m/s (184 ft/s) for liquid oxygen. The test results indicate that the vanes probably cannot be scaled up with pipe size, at least not linearly.

  17. Thermal dispersion in vertical gas-liquid flows with foaming and non-foaming liquids

    SciTech Connect

    Pino, L.R.Z.; Saez, A.E.

    1995-05-01

    Heat transfer experiments have been performed in gas-liquid upwards flow in a vertical column with non-foaming (water) and foaming (kerosene) liquids. The main purpose of the experiments has been to characterized the degree of thermal mixing in the system. For the range of conditions employed, the nonfoaming liquid exhibits complete mixing a low liquid superficial velocities. An increased in liquid velocity leads to incomplete mixing. In the latter case, the thermal dispersion coefficient at low gas superficial velocities is larger than what correlations in the literature predict. For the foaming liquid, when foaming and bubbling regions coexist in the bubble column, each region behaves as a completely-mixed subsystem.

  18. Two-phase stopped-flow measurement of the protonation of tetraphenylporphyrin at the liquid-liquid interface.

    PubMed

    Nagatani, H; Watarai, H

    1996-04-01

    The formation rate of the protonated form of tetraphenylporphyrin (TPP) in a dispersed two-phase system composed of dodecane and aqueous trichloroacetic acid (TCA) was studied by means of a stopped-flow method. The protonation reaction took place at the liquid-liquid interface, and the diprotonated TPP (H(2)TPP(2+)) formed was adsorbed there. In order to determine the rate-determining process, changes in absorbance at the absorption maximum wavelengths of TPP and H(2)TPP(2+) were analyzed. The obtained rate constant for the decrease of TPP in the organic phase, 21 ± 2 s(-1), was in agreement with that for the increase of diprotonated TPP at the interface, 20 ± 3 s(-1). The observed rate constants did not show any dependence on concentrations of both TPP and the acid. The experimental results suggested the rate-determining step to be the molecular diffusion process of TPP in the stagnant layer in the organic phase side at the liquid-liquid interface, and the thickness of the stagnant layer was estimated as 1.4 × 10(-4) cm. PMID:21619156

  19. Liquid rocket engine centrifugal flow turbopumps. [design criteria

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Design criteria and recommended practices are discussed for the following configurations selected from the design sequence of a liquid rocket engine centrifugal flow turbopump: (1) pump performance including speed, efficiency, and flow range; (2) impeller; (3) housing; and (4) thrust balance system. Hydrodynamic, structural, and mechanical problems are addressed for the achievement of required pump performance within the constraints imposed by the engine/turbopump system. Materials and fabrication specifications are also discussed.

  20. The use of liquid crystals for surface flow visualization

    NASA Technical Reports Server (NTRS)

    Smith, Stephen C.

    1990-01-01

    The use of shear-sensitive liquid crystals has become an established technique for diagnostic flow visualization. This technique has been demonstrated to illustrate laminar boundary-layer transition, laminar bubbles, shocks, and separation in flight and wind-tunnel environments. Typical results demonstrate the range of flow features which can be illustrated and some of the challenges and pitfalls which must be addressed. A few remaining issues are discussed which should be resolved to develop this technique to full maturity.

  1. The temperature measurement research for high-speed flow based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Di, Yue; Jin, Yi; Jiang, Hong-liang; Zhai, Chao

    2013-09-01

    Due to the particularity of the high-speed flow, in order to accurately obtain its' temperature, the measurement system should has some characteristics of not interfereing with the flow, non-contact measurement and high time resolution. The traditional measurement method cannot meet the above requirements, however the measurement method based on tunable diode laser absorption spectroscopy (TDLAS) technology can meet the requirements for high-speed flow temperature measurement. When the near-infared light of a specific frequency is through the media to be measured, it will be absorbed by the water vapor molecules and then the transmission light intensity is detected by the detector. The temperature of the water vapor which is also the high-speed flow temperature, can be accurately obtained by the Beer-Lambert law. This paper focused on the research of absorption spectrum method for high speed flow temperature measurement with the scope of 250K-500K. Firstly, spectral line selection method for low temperature measurement of high-speed flow is discussed. Selected absorption lines should be isolated and have a high peak absorption within the range of 250-500K, at the same time the interference of the other lines should be avoided, so that a high measurement accuracy can be obtained. According to the near-infrared absorption spectra characteristics of water vapor, four absorption lines at the near 1395 nm and 1409 nm are selected. Secondly, a system for the temperature measurement of the water vapor in the high-speed flow is established. Room temperature are measured through two methods, direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) ,the results show that this system can realize on-line measurement of the temperature and the measurement error is about 3%. Finally, the system will be used for temperature measurement of the high-speed flow in the shock tunnel, its feasibility of measurement is analyzed.

  2. Estimation of Liquid Wall and Interfacial Shear Stress in Horizontal Stratified Gas-liquid Pipe Flow

    NASA Astrophysics Data System (ADS)

    Liu, Yiping; Zhang, Hua; Wang, Jing

    2007-06-01

    A modified two-phase shear stress calculation method for pipe flow problems is explored. A force balance has been set up on the control volume of liquid phase to determine the interfacial friction factor by employing both the measured pressure gradient and liquid height. The gradient of height of liquid layer has been taken into account, which is suitable for the case where the interface may be smooth, rippled or wavy. The correlation of model indicates that the careful estimation for liquid-wall shear stress is necessary, and the assumption of a stationary liquid element is not applicable for the case of higher gas flow rates. The interfacial friction factor evaluated indirectly from experimental liquid height and pressure loss measurements, which are obtained in 50mm ID pipeline for air and water in cocurrent stratified flow, is used to achieve its correlation with the combination of characteristic parameters. The evaluation of new correlation has been conducted by the comparison of the predicted pressure drop with the experimental data. The performance of correlation depends on the form of the gas-liquid interface.

  3. Two parametric flow measurement in gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Chen, C.; Xu, Y.; Zhao, Z.

    The importance and current development of two parametric measurement during two-phase flow are briefly reviewed in this paper. Gas-liquid two-phase two parametric metering experiments were conducted by using an oval gear meter and a sharp edged orifice mounted in series in a horizontal pipe. Compressed air and water were used as gas and liquid phases respectively. The correlations, which can be used to predict the total flow rate and volumetric quality of two-phase flow or volumetric flow rate of each phase, have also been proposed in this paper. Comparison of the calculated values of flow rate of each phase from the correlations with the test data showed that the root mean square fractional deviation for gas flow rate is 2.9 percent and for liquid flow rate 4.4 percent. The method proposed in this paper can be used to measure the gas and liquid flow rate in two-phase flow region without having to separate the phases.

  4. Thermocapillary flows in two-fluids liquid bridges

    NASA Astrophysics Data System (ADS)

    Viviani, A.; Golia, C.

    2003-12-01

    In this paper we consider the flow and interfaces deformation in non-isothermal two-liquids bridges, i.e. in liquid bridges held between two parallel planar disks, posed at different temperature, which are composed by two coaxial immiscible liquid columns, an inner column of liquid ( a) forming an axisymmetric interface with an outer annular column of liquid ( b) bounded by a free surface from the external still gas. The motion in the two bulk phases arises due to surface gradients of the interface tensions, induced by the imposed temperature difference, both at the liquid-liquid interface and at the external free surface; for the interface tensions it is assumed a linear dependence on the temperature. Under the hypothesis of Reynolds, Peclet and capillary numbers very small, the field equations are expanded in a series of successive linear approximations; the zeroth-order approximation is the Stokes problem, that is analytically solved via separation of variables in terms of infinite series of modified first-order Bessel functions of first and second kind and Papkovitch-Fadle bi-orthogonal eigenfunctions. To improve convergence of the series, Cesaro sums are used. The solution is given for the zeroth order temperature, velocity and pressure fields and for the first-order deviation of the interfaces from the hydrostatic shape. Streamlines, velocity profiles and interface shapes are presented and discussed in terms of Marangoni numbers, viscosity ratio of the two bulk phases and aspect ratios of the two liquid columns.

  5. Thermohydrodynamic Analysis of Cryogenic Liquid Turbulent Flow Fluid Film Bearings

    NASA Technical Reports Server (NTRS)

    SanAndres, Luis

    1996-01-01

    Computational programs developed for the thermal analysis of tilting and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings are described. The motion of a cryogenic liquid on the thin film annular region of a fluid film bearing is described by a set of mass and momentum conservation, and energy transport equations for the turbulent bulk-flow velocities and pressure, and accompanied by thermophysical state equations for evaluation of the fluid material properties. Zeroth-order equations describe the fluid flow field for a journal static equilibrium position, while first-order (linear) equations govern the fluid flow for small amplitude-journal center translational motions. Solution to the zeroth-order flow field equations provides the bearing flow rate, load capacity, drag torque and temperature rise. Solution to the first-order equations determines the rotordynamic force coefficients due to journal radial motions.

  6. Asymmetric energy flow in liquid alkylbenzenes: A computational study

    SciTech Connect

    Leitner, David M.; Pandey, Hari Datt

    2015-10-14

    Ultrafast IR-Raman experiments on substituted benzenes [B. C. Pein et al., J. Phys. Chem. B 117, 10898–10904 (2013)] reveal that energy can flow more efficiently in one direction along a molecule than in others. We carry out a computational study of energy flow in the three alkyl benzenes, toluene, isopropylbenzene, and t-butylbenzene, studied in these experiments, and find an asymmetry in the flow of vibrational energy between the two chemical groups of the molecule due to quantum mechanical vibrational relaxation bottlenecks, which give rise to a preferred direction of energy flow. We compare energy flow computed for all modes of the three alkylbenzenes over the relaxation time into the liquid with energy flow through the subset of modes monitored in the time-resolved Raman experiments and find qualitatively similar results when using the subset compared to all the modes.

  7. Dynamic Modeling Strategy for Flow Regime Transition in Gas-Liquid Two-Phase Flows

    SciTech Connect

    Xia Wang; Xiaodong Sun; Benjamin Doup; Haihua Zhao

    2012-12-01

    In modeling gas-liquid two-phase flows, the concept of flow regimes has been widely used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are flow regime dependent. Current nuclear reactor safety analysis codes, such as RELAP5, classify flow regimes using flow regime maps or transition criteria that were developed for steady-state, fully-developed flows. As twophase flows are dynamic in nature, it is important to model the flow regime transitions dynamically to more accurately predict the two-phase flows. The present work aims to develop a dynamic modeling strategy to determine flow regimes in gas-liquid two-phase flows through introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation of the interfacial area, fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation, and the destruction of the interfacial area, fluid particle coalescence and condensation. For flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shapes, namely group-1 and group-2 bubbles. A preliminary approach to dynamically identify the flow regimes is discussed, in which discriminator s are based on the predicted information, such as the void fraction and interfacial area concentration. The flow regime predicted with this method shows good agreement with the experimental observations.

  8. Effect of liquid viscosity on wave behavior in gas-liquid two-phase flow

    SciTech Connect

    Kondo, Yoshiyuki; Mori, Koji; Yagishita, Takuya; Nakabo, Akinobu

    1999-07-01

    Measurements of time-spatial distributions of liquid holdups for the vertical upward gas-liquid two-phase flow were carried out by using the supermultiple cross-sectional mean liquid holdup probes (S-CHOP) and the semi-supermultiple point-electrode probes (SS-PEP) in the wide range of superficial gas and liquid velocity, j{sub g} and j{sub {ell}}, and the liquid kinematic viscosities were {nu}{sub {ell}} = 1 x 10{sup {minus}6}, 10 x 10{sup {minus}6} and 20 x 10{sup {minus}6} m{sup 1}/s. The time-spatial maps of wave behavior and the interfacial profiles were presented. Close inspection of these results reveals that there also exist huge waves and disturbance waves in the higher liquid viscosity conditions. To clarify the characteristics of these waves, the wave-vein analysis and the cluster analysis by K-mean algorithm were applied. These methods distinguished huge wave and disturbance wave objectively. The appearance regions of liquid slug, huge wave, and disturbance wave for each liquid viscosity condition were presented and the effects of liquid viscosity on them were discussed. Furthermore, velocity, width and height of these waves were determined, and the effects of liquid viscosity on them were clarified.

  9. How do entangled polymeric liquids flow?

    NASA Astrophysics Data System (ADS)

    Sundar Ravindranath, Sham; Wang, Shi-Qing

    2009-03-01

    This work focused on investigating fundamental questions in polymer dynamics such as how entangled polymeric liquids respond to fast external deformation. By developing an effective particle tracking velocimetric (PTV) method, along with conventional rheometric measurements, new insights can be gained into the phenomenology of entangled polymers in presence of startup shear, step strain and large amplitude oscillatory shear (LAOS). During startup shear of well entangled systems, the shear field becomes inhomogeneous after the stress overshoot for a range of applied shear rates beyond the Newtonian region [1]. The emergence of shear banding after stress overshoot helped us to identify the stress overshoot as indicating yielding, whose characteristics obey some scaling laws. In step shear, contrary to the conventional perception that entangled polymers would undergo quiescent relaxation, the PTV observations reveal macroscopic motions after shear cessation [2]. The recoil-like macroscopic motions appears to reflect an elastic breakdown of the entanglement network due to sufficient build-up of retractive forces. LAOS experiments also demonstrate that entangled polymers cannot sustain a high magnitude of fast deformation without undergoing cohesive failure [3]. [1] Macromolecules 2008, 41, 2663 [2] Macromolecules 2007, 40, 8031 [3] J. Rheol. 2008, 52, 341.

  10. Measurements of liquid film thickness, concentration, and temperature of aqueous urea solution by NIR absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Pan, R.; Jeffries, J. B.; Dreier, T.; Schulz, C.

    2016-01-01

    A multi-wavelength near-infrared (NIR) diode laser absorption sensor has been developed and demonstrated for real-time monitoring of the thickness, solute concentration, and temperature of thin films of urea-water solutions. The sensor monitors the transmittance of three near-infrared diode lasers through the thin liquid film. Film thickness, urea mass fraction, and liquid temperature were determined from measured transmittance ratios of suitable combinations of lasers. Available laser wavelengths were selected depending on the variation of the NIR absorption spectrum of the solution with temperature and solute concentration. The spectral database was measured by a Fourier transform infrared spectrometer in the range 5500-8000 cm-1 for urea solutions between 5 and 40 wt% and temperatures between 298 and 338 K. A prototype sensor was constructed, and the sensor concept was first validated with measurements using a calibration cell providing liquid layers of variable thickness (200-1500 µm), urea mass fraction (5-40 wt%) and temperature (298-318 K). Temporal variations of film thickness and urea concentration were captured during the constant-temperature evaporation of a liquid film deposited on an optically polished heated quartz flat.

  11. Free surface and flow problem for a viscous liquid

    SciTech Connect

    Zaytsev, M. L. Akkerman, V. B.

    2011-10-15

    An exact closed system of equations is proposed for describing the shape of the free surface of a viscous steady-state liquid in the 2D case in terms of the surface itself. A method that lowers the dimensionality in the Navier-Stokes equation is demonstrated, and its application in problems of steady-state flow past solids is considered.

  12. Pump-Flow-Probe X-Ray Absorption Spectroscopy as a Tool for Studying Intermediate States of Photocatalytic Systems

    PubMed Central

    Smolentsev, Grigory; Guda, Alexander; Zhang, XIaoyi; Haldrup, Kristoffer; Andreiadis, Eugen; Chavarot-Kerlidou, Murielle; Canton, Sophie E.; Nachtegaal, Maarten; Artero, Vincent; Sundstrom, Villy

    2014-01-01

    A new setup for pump-flow-probe X-ray absorption spectroscopy has been implemented at the SuperXAS beamline of the Swiss Light Source. It allows recording X-ray absorption spectra with a time resolution of tens of microseconds and high detection efficiency for samples with sub-mM concentrations. A continuous wave laser is used for the photoexcitation, with the distance between laser and X-ray beams and velocity of liquid flow determining the time delay, while the focusing of both beams and the flow speed define the time resolution. This method is compared with the alternative measurement technique that utilizes a 1 kHz repetition rate laser and multiple X-ray probe pulses. Such an experiment was performed at beamline 11ID-D of the Advanced Photon Source. Advantages, limitations and potential for improvement of the pump-flow-probe setup are discussed by analyzing the photon statistics. Both methods, with Co K-edge probing were applied to the investigation of a cobaloxime-based photo-catalytic reaction. The interplay between optimizing for efficient photoexcitation and time resolution as well as the effect of sample degradation for these two setups are discussed. PMID:24443663

  13. Revisiting the total ion yield x-ray absorption spectra of liquid water microjets

    SciTech Connect

    Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

    2008-02-16

    Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical.

  14. CFD simulation on the turbulent mixing flow performance of the liquid-liquid ejector

    NASA Astrophysics Data System (ADS)

    An, W. Z.; Bie, H. Y.; Liu, C. C.; Hao, Z. R.

    2016-05-01

    In order to study the flow performance of the liquid-liquid ejector, 3D ejector simulation models were established to investigate the influences of suction angle, suction number and working condition on the ejector performance. The simulation results showed that when the suction angle was 60°, the total pressure was in equilibrium state. The double suction ejector would induced more vortexes in the suction chamber than that of the single suction ejector, and the turbulent intensity of the fluid inside the ejector was bigger, however, it also caused much more loss in energy. When the working pressure was lower than 0.6 MPa, the liquid entrainment ratio increased rapidly. Once the working pressure reached 0.6 MPa, the liquid entrainment ratio basically remained unchanged. The mass flow rate of the suction medium increased with the increasing of suction pressure, and the differential pressure between the suction pressure and the working pressure at the nozzle also increased simultaneously.

  15. Basic study on hot-wire flow meter in forced flow of liquid hydrogen

    NASA Astrophysics Data System (ADS)

    Oura, Y.; Shirai, Y.; Shiotsu, M.; Murakami, K.; Tatsumoto, H.; Naruo, Y.; Nonaka, S.; Kobayashi, H.; Inatani, Y.; Narita, N.

    2014-01-01

    Liquid hydrogen (LH2) is a key issue in a carbon-free energy infrastructure at the energy storage and transportation stage. The typical features of LH2 are low viscosity, large latent heat and small density, compared with other general liquids. It is necessary to measure a mass flow of liquid hydrogen with a simple and compact method, especially in a two phase separate flow condition. We have proposed applying a hot-wire type flow meter, which is usually used a for gas flow meter, to LH2 flow due to the quite low viscosity and density. A test model of a compact LH2 hot-wire flow meter to measure local flow velocities near and around an inside perimeter of a horizontal tube by resistance thermometry was designed and made. The model flow meter consists of two thin heater wires made of manganin fixed in a 10 mm-diameter and 40 mm-length tube flow path made of GFRP. Each rigid heater wire was set twisted by 90 degrees from the inlet to the outlet along the inner wall. In other words, the wires were aslant with regard to the LH2 stream line. The heated wire was cooled by flowing LH2, and the flow velocity was obtained by means of the difference of the cooling characteristic in response to the flow velocity. In this report, we show results on the basic experiments with the model LH2 hot-wire flow meter. First, the heat transfer characteristics of the two heater wires for several LH2 flow velocities were measured. Second, the heating current was controlled to keep the wire temperature constant for various flow velocities. The relations between the flow velocity and the heating current were measured. The feasibility of the proposed model was confirmed.

  16. Liquid-Crystal Coats Help Make Flows Visible

    NASA Technical Reports Server (NTRS)

    Holmes, Bruce J.; Obara, Clifford J.

    1991-01-01

    Visible indication of transition of boundary layer from laminar to turbulent flow plays important role in aerodynamic tests in wind tunnels and in flight. In newly developed method, liquid-crystal coats used to make visible such features of boundary-layer flows as transitions, separations, and locations of shocks. Changes of color rapid and reversible. For flight applications, provides capability for making transitions visible throughout almost entire altitude and speed ranges of subsonic aircraft. Also applicable to visible indication of supersonic flows and suitable for general use in high- and low-speed wind-tunnel and water-tunnel testing.

  17. Numerical and experimental analysis of a thin liquid film on a rotating disk related to development of a spacecraft absorption cooling system

    NASA Technical Reports Server (NTRS)

    Faghri, Amir; Swanson, Theodore D.

    1989-01-01

    The numerical and experimental analysis of a thin liquid film on a rotating and a stationary disk related to the development of an absorber unit for a high capacity spacecraft absorption cooling system, is described. The creation of artificial gravity by the use of a centrifugal field was focused upon in this report. Areas covered include: (1) One-dimensional computation of thin liquid film flows; (2) Experimental measurement of film height and visualization of flow; (3) Two-dimensional computation of the free surface flow of a thin liquid film using a pressure optimization method; (4) Computation of heat transfer in two-dimensional thin film flow; (5) Development of a new computational methodology for the free surface flows using a permeable wall; (6) Analysis of fluid flow and heat transfer in a thin film in the presence and absence of gravity; and (7) Comparison of theoretical prediction and experimental data. The basic phenomena related to fluid flow and heat transfer on rotating systems reported here can also be applied to other areas of space systems.

  18. Fluid flow effects in evaporation from liquid-vapor meniscus

    SciTech Connect

    Khrustalev, D.; Faghri, A.

    1996-12-31

    A mathematical model of the evaporating liquid-vapor meniscus in a capillary slot has been developed. The model includes two-dimensional steady-state momentum conservation and energy equations for both the vapor and liquid phases, and incorporates the existing simplified one-dimensional model of the evaporating microfilm. The numerical results, obtained for water, demonstrate the importance of accounting for the fluid flow in calculating the effective evaporative heat transfer coefficient and the superheat of the vapor over the liquid-vapor meniscus due to the heat transfer from the heated wall. With higher heat fluxes, a recirculation zone appears in the vapor near the heated wall due to the extensive evaporation in the thin-film region of the liquid-vapor meniscus.

  19. Signals features extraction in liquid-gas flow measurements using gamma densitometry. Part 1: time domain

    NASA Astrophysics Data System (ADS)

    Hanus, Robert; Zych, Marcin; Petryka, Leszek; Jaszczur, Marek; Hanus, Paweł

    2016-03-01

    The paper presents an application of the gamma-absorption method to study a gas-liquid two-phase flow in a horizontal pipeline. In the tests on laboratory installation two 241Am radioactive sources and scintillation probes with NaI(Tl) crystals have been used. The experimental set-up allows recording of stochastic signals, which describe instantaneous content of the stream in the particular cross-section of the flow mixture. The analyses of these signals by statistical methods allow to determine the mean velocity of the gas phase. Meanwhile, the selected features of signals provided by the absorption set, can be applied to recognition of the structure of the flow. In this work such three structures of air-water flow as: plug, bubble, and transitional plug - bubble one were considered. The recorded raw signals were analyzed in time domain and several features were extracted. It was found that following features of signals as the mean, standard deviation, root mean square (RMS), variance and 4th moment are most useful to recognize the structure of the flow.

  20. Use of laminar flow and unstirred layer models to predict intestinal absorption in the rat.

    PubMed Central

    Levitt, M D; Kneip, J M; Levitt, D G

    1988-01-01

    Carbon monoxide (CO) and [14C]warfarin were used to measure the preepithelial diffusion resistance resulting from poor luminal stirring (RL) in the constantly perfused rat jejunum at varying degrees of distension (0.05, 0.1, and 0.2 ml/cm). RL was much greater than epithelial cell resistance, indicating that poor stirring was the limiting factor in absorption and that an appropriate model of stirring should accurately predict absorption. A laminar flow model accurately predicted the absorption rate of both probes at all levels of gut distension, as well as the absorption of glucose when RL was the rate-limiting factor in absorption. In contrast, an unstirred layer model would not have predicted that gut distension would have little influence on absorption, and would have underestimated [14C]warfarin absorption relative to CO. We concluded that in the perfused rat jejunum, laminar flow accurately models luminal stirring and an unstirred layer should be considered to be a unit of resistance in laminar flow, rather than a model of luminal stirring. PMID:3366899

  1. Flow Visualization of Liquid Hydrogen Line Chilldown Tests

    NASA Technical Reports Server (NTRS)

    Rame, Enrique; Hartwig, Jason W.; McQuillen John B.

    2014-01-01

    We present experimental measurements of wall and fluid temperature during chill-down tests of a warm cryogenic line with liquid hydrogen. Synchronized video and fluid temperature measurements are used to interpret stream temperature profiles versus time. When cold liquid hydrogen starts to flow into the warm line, a sequence of flow regimes, spanning from all-vapor at the outset to bubbly with continuum liquid at the end can be observed at a location far downstream of the cold inlet. In this paper we propose interpretations to the observed flow regimes and fluid temperature histories for two chilldown methods, viz. trickle (i.e. continuous) flow and pulse flow. Calculations of heat flux from the wall to the fluid versus wall temperature indicate the presence of the transition/nucleate boiling regimes only. The present tests, run at typical Reynolds numbers of approx O(10 (exp 5)), are in sharp contrast to similar tests conducted at lower Reynolds numbers where a well-defined film boiling region is observed.

  2. Liquid plug flow in a vertical two-dimensional channel

    NASA Astrophysics Data System (ADS)

    Bull, Joseph; Halpern, David; Grotberg, James

    2001-11-01

    Gravity and pressure driven liquid plug flow in a two-dimensional vertical channel is investigated as a model of instilled liquid transport in the lungs. There are a number of clinical situations in which liquids are instilled into the lungs. Of particular interest is liquid ventilation where perfluorocarbon liquids are delivered to the lung and subsequently used for ventilation in place of gas. Additionally the perfuorocarbon can be used as a carrier for drugs or genetic material. Some other examples of liquid instillation into the lungs include surfactant replacement therapy, lung lavage, and cardio-pulmonary resuscitation. The desired distribution of liquid depends on the application. Our model is developed using the Stokes equation subject to interfacial and wall boundary conditions, and is solved using the boundary element method. We obtain steady-state and time-dependent solutions. As the plug propagates along the thin-film-lined channel, it takes up liquid from the leading film and deposit liquid in the trailing film. The trailing film thickness, interface shapes and plug speed are determined as functions of the parameters of the problem, Bond number, driving pressure, and leading film thickness and initial plug length for the time-dependent problem. These results are important clinically since the trailing film thickness determines when the plug ruptures affecting the ultimate liquid distribution, and thicker films can result in airway closure. This research was supported by NIH grants HL41126, HL64373, and HL54224-04S1. J.L. Bull is a Parker B. Francis Fellow in Pulmonary Research.

  3. IHT: Tools for Computing Insolation Absorption by Particle Laden Flows

    2013-09-17

    INT is a toolkit for computing radiative heat exchange between particles. The algorithm is based on the the 'Photon Monte Carlo" approach described by Wang and Modest and implemented as a library that can be interfaced with a variety of CFD codes to analyze radiative heat transfer in particle laden flows.

  4. Topological transitions in unidirectional flow of nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Cummings, Linda; Anderson, Thomas; Mema, Ensela; Kondic, Lou

    2015-11-01

    Recent experiments by Sengupta et al. (Phys. Rev. Lett. 2013) revealed interesting transitions that can occur in flow of nematic liquid crystal under carefully controlled conditions within a long microfluidic channel of rectangular cross-section, with homeotropic anchoring at the walls. At low flow rates the director field of the nematic adopts a configuration that is dominated by the surface anchoring, being nearly parallel to the channel height direction over most of the cross-section; but at high flow rates there is a transition to a flow-dominated state, where the director configuration at the channel centerline is aligned with the flow (perpendicular to the channel height direction). We analyze simple channel-flow solutions to the Leslie-Ericksen model for nematics. We demonstrate that two solutions exist, at all flow rates, but that there is a transition between the elastic free energies of these solutions: the anchoring-dominated solution has the lowest energy at low flow rates, and the flow-dominated solution has lowest energy at high flow rates. NSF DMS 1211713.

  5. Ultrasound Doppler Velocimetry Measurements in Turbulent Liquid Metal Channel Flow

    NASA Astrophysics Data System (ADS)

    Rivero, Michel; Jian, Dandan; Karcher, Christian; Cuevas, Sergio

    2010-11-01

    Control of molten metal flow using magnetic fields is important in industrial applications. The Electromagnetic Flow Control Channel (EFCO) is an experimental test facility, located at Ilmenau University of Technology, for the development of such kind of control systems. The working fluid is the low-melting liquid metal alloy GaInSn in eutectic composition. In this channel, flow control is realized by combining and coupling the non-contact flow driving technology of electromagnetic pumps based on rotating permanent magnets and the non-contact flow rate measurement technology termed Lorentz Force Velocimetry (LFV). The flow rate is adjusted by controlling the rotation rate of the permanent magnet system. Physically, LFV is based on measuring the force acting on a magnet system. This force is induced by the melt flow passing through the static magnetic field generated by the system and is proportional to the flow. To calibrate such flow meters, we apply UDV technique to measure and analyse both turbulent hydrodynamic and MHD flow profiles in EFCO at various Reynolds numbers.

  6. Absorption spectra and photolysis of methyl peroxide in liquid and frozen water.

    PubMed

    Epstein, Scott A; Shemesh, Dorit; Tran, Van T; Nizkorodov, Sergey A; Gerber, R Benny

    2012-06-21

    Methyl peroxide (CH(3)OOH) is commonly found in atmospheric waters and ices in significant concentrations. It is the simplest organic peroxide and an important precursor to hydroxyl radical. Many studies have examined the photochemical behavior of gaseous CH(3)OOH; however, the photochemistry of liquid and frozen water solutions is poorly understood. We present a series of experiments and theoretical calculations designed to elucidate the photochemical behavior of CH(3)OOH dissolved in liquid water and ice over a range of temperatures. The molar extinction coefficients of aqueous CH(3)OOH are different from the gas phase, and they do not change upon freezing. Between -12 and 43 °C, the quantum yield of CH(3)OOH photolysis is described by the following equation: Φ(T) = exp((-2175 ± 448)1/T) + 7.66 ± 1.56). We use on-the-fly ab initio molecular dynamics simulations to model structures and absorption spectra of a bare CH(3)OOH molecule and a CH(3)OOH molecule immersed inside 20 water molecules at 50, 200, and 220 K. The simulations predict large sensitivity in the absorption spectrum of CH(3)OOH to temperature, with the spectrum narrowing and shifting to the blue under cryogenic conditions because of constrained dihedral motion around the O-O bond. The shift in the absorption spectrum is not observed in the experiment when the CH(3)OOH solution is frozen suggesting that CH(3)OOH remains in a liquid layer between the ice grains. Using the extinction coefficients and photolysis quantum yields obtained in this work, we show that under conditions with low temperatures, in the presence of clouds with a high liquid-water content and large solar zenith angles, the loss of CH(3)OOH by aqueous photolysis is responsible for up to 20% of the total loss of CH(3)OOH due to photolysis. Gas phase photolysis of CH(3)OOH dominates under all other conditions. PMID:22217262

  7. Numerical modeling of liquid-liquid bi-propellant droplet/gas reacting flows

    NASA Astrophysics Data System (ADS)

    Tang, Yupai L.; Schuman, M. D.

    1992-01-01

    A liquid-liquid bipropellant capability for numerically simulating droplets and gas two-phase flows for impinging type rocket injectors was developed through modification of the KIVA-II computer program. This added feature of liquid-liquid bipropellant sprays makes it possible to analyze the impinging type injectors through prescribed drop size and velocity distributions near the point of impingement. Two sample cases for LOX/liquid propane were run at mixture ratios of 3.06 and 2.72 respectively for a 3.4-inch diameter rocket engine with a contraction ratio of four and an expansion ratio of two. The predicted performance as well as the chamber heat transfer were found to be in reasonable agreement with the experimental data.

  8. Effect of water on the carbon dioxide absorption by 1-alkyl-3-methylimidazolium acetate ionic liquids.

    PubMed

    Stevanovic, Stéphane; Podgoršek, Ajda; Pádua, Agilio A H; Costa Gomes, Margarida F

    2012-12-13

    The absorption of carbon dioxide by the pure ionic liquids 1-ethyl-3-methylimidazolium acetate ([C(1)C(2)Im][OAc]) and 1-butyl-3-methylimidazolium acetate ([C(1)C(4)Im][OAc]) was studied experimentally from 303 to 343 K. As expected, the mole fraction of absorbed carbon dioxide is high (0.16 at 303 K and 5.5 kPa and 0.19 at 303 and 9.6 KPa for [C(1)C(2)Im][OAc] and [C(1)C(4)Im][OAc], respectively), does not obey Henry's law, and is compatible with the chemisorption of the gas by the liquid. Evidence of a chemical reaction between the gas and the liquid was found both by NMR and by molecular simulation. In the presence of water, the properties of the liquid absorber significantly change, especially the viscosity that decreases by as much as 25% (to 78 mPa s) and 30% (to 262 mPa s) in the presence of 0.2 mol fraction of water for [C(1)C(2)Im][OAc] and [C(1)C(2)Im][OAc] at 303 K, respectively. The absorption of carbon dioxide decreases when the water concentration increases: a decrease of 83% in CO(2) absorption is found for [C(1)C(4)Im][OAc] with 0.6 mol fraction of water at 303 K. It is proved in this work, by combining experimental data with molecular simulation, that the presence of water not only renders the chemical reaction between the gas and the ionic liquid less favorable but also lowers the (physical) solubility of the gas as it competes by the same solvation sites of the ionic liquid. The lowering of the viscosity of the liquid absorbent largely compensates these apparent drawbacks and the mixtures of [C(1)C(2)Im][OAc] and [C(1)C(2)Im][OAc] with water seem promising to be used for carbon dioxide capture. PMID:23145571

  9. Parallel magnetic resonance imaging of gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Mueller, Christoph; Penn, Alexander; Pruessmann, Klaas P.

    2015-03-01

    Gas-liquids flows are commonly encountered in nature and industry. Experimental measurements of gas-liquid flows are challenging since such systems can be visually opaque and highly dynamic. Here we report the implementation of advanced magnetic resonance imaging (MRI) strategies allowing us to probe the dynamics (voidage and velocity measurements) of gas-liquid flows with ultra-fast acquisition speeds. Specifically, parallel MRI which exploits the spatial encoding capabilities of multiple receiver coils was implemented. To this end a tailored, 16 channels MR receive array was constructed and employed in the MR acquisition. A magnetic susceptibility matched gas-liquid system was set-up and used to probe the motion, splitting and coalescence of bubbles. The temporal and spatial resolution of our acquired data was 5 ms and 3.5 mm x 3.5 mm, respectively. The total field of view was 200 mm x 200 mm. We will conclude with an outlook of further possible advances in MRI that have the potential to reduce substantially the acquisition time, providing flexible gains in temporal and spatial resolution.

  10. Analysis of Developing Gas/liquid Two-Phase Flows

    SciTech Connect

    Elena A. Tselishcheva; Michael Z. Podowski; Steven P. Antal; Donna Post Guillen; Matthias Beyer; Dirk Lucas

    2010-06-01

    The goal of this work is to develop a mechanistically based CFD model that can be used to simulate process equipment operating in the churn-turbulent regime. The simulations were performed using a state-of-the-art computational multiphase fluid dynamics code, NPHASE–CMFD [Antal et al,2000]. A complete four-field model, including the continuous liquid field and three dispersed gas fields representing bubbles of different sizes, was first carefully tested for numerical convergence and accuracy, and then used to reproduce the experimental results from the TOPFLOW test facility at Forschungszentrum Dresden-Rossendorf e.V. Institute of Safety Research [Prasser et al,2007]. Good progress has been made in simulating the churn-turbulent flows and comparison the NPHASE-CMFD simulations with TOPFLOW experimental data. The main objective of the paper is to demonstrate capability to predict the evolution of adiabatic churn-turbulent gas/liquid flows. The proposed modelling concept uses transport equations for the continuous liquid field and for dispersed bubble fields [Tselishcheva et al, 2009]. Along with closure laws based on interaction between bubbles and continuous liquid, the effect of height on air density has been included in the model. The figure below presents the developing flow results of the study, namely total void fraction at different axial locations along the TOPFLOW facility test section. The complete model description, as well as results of simulations and validation will be presented in the full paper.

  11. Solidlike coherent vibronic dynamics in a room temperature liquid: Resonant Raman and absorption spectroscopy of liquid bromine

    NASA Astrophysics Data System (ADS)

    Branigan, Edward T.; van Staveren, Marie N.; Apkarian, V. Ara

    2010-01-01

    UV-visible absorption and resonance Raman (RR) spectra of liquid bromine are presented and rigorously interpreted. The RR spectra, which show an anharmonic vibrational progression of up to 30 overtones, define the ground state potential in the range 2.05 Åliquid phase, indicating an attractive cage-molecule interaction. The excited state potentials (A', B, and C) are extracted from the absorption spectrum. The spectrum is first inverted under assumption of the classical reflection approximation, then corrected by forward simulations through quantum time correlations. The extrapolated B and C potentials are used to simulate RR spectra. Their validity is cross-checked by the interference pattern of the polarized spectra due to two-channel RR scattering. The discrepancy between calculated and observed intensities can be entirely assigned to vibrational dephasing, which is observed to follow the exponential energy gap law—dephasing rates perfectly trace the Birge-Sponer plot of the vibrational progression—suggesting that vibrational dissipation controls the decay of coherence. Despite strong intermolecular electronic interactions and vibrational energy gaps of ˜kT, vibrational coherences are long lived: Coherence times range from ≥25 to ≥2.4 ps between v =1 and v =25. Remarkably, the RR line shapes are skewed toward the red, indicating upchirp in frequencies that develop over a period of 400 fs. Evidently, the molecular vibrations adiabatically follow the solvent cage, which is impulsively driven into expansion during the ˜20 fs evolution on the electronically excited state. Liquid bromine retains coherence in ordered sluggish local cages with quadrupolar interactions—dynamics akin to molecules isolated in structured cryogenic rare gas solids.

  12. Liquid-liquid extraction based on a new flow pattern: Two-fluid Taylor-Couette flow

    NASA Astrophysics Data System (ADS)

    Baier, Gretchen

    The exploitation of flow instabilities that can occur in rotating flows is investigated as a new approach to liquid extraction. Two immiscible liquids are radially stratified by centrifugal force in the annulus between corotating coaxial cylinders. The inner cylinder is rotated above a critical speed to form Taylor vortices in one or both of the fluids. This flow pattern produces a relatively small amount interfacial surface area that is of highly active for interphase mass transfer. Continuous processing is also possible with the addition of countercurrent axial flow. The present study includes: (1)A review of aqueous- aqueous and reversed micelle extraction techniques, the commercially available centrifugal extractors, and one fluid Taylor-Couette flow and its variations. (2)A theoretical analysis to predict the onset of the two- fluid Taylor-Couette instability in the presence of countercurrent axial flow. (3)Theoretical predictions for interphase mass transfer using penetration theory and computational fluid dynamics. (4)The demonstration of two-fluid Taylor-Couette flow with countercurrent axial flow in the laboratory, including: (1) fluid mechanics studies to determine the onset of vortices, and (2) mass transfer studies to characterize intraphase and interphase mass transfer. The agreement between the experiments and theory is good for both the fluid mechanics and the mass transfer. Furthermore, the extraction performance is quite promising with the mass transfer coefficient approximately proportional to the vortex strength. Even higher extraction efficiencies should be obtainable with even larger relative rotation rates or cylinder modification to promote vortex formation. Besides two-fluid Taylor-Couette flow, other instabilities can also occur. With low viscosity fluids at low rotation rates, the ``barber pole'' pattern is observed experimentally and is believed to be a lingering gravitational effect. At high countercurrent axial flowrates, the linear

  13. Automated continuous monitoring of inorganic and total mercury in wastewater and other waters by flow-injection analysis and cold-vapour atomic absorption spectrometry

    PubMed Central

    Birnie, S. E.

    1988-01-01

    An automated continuous monitoring system for the determination of inorganic and total mercury by flow-injection analysis followed by cold-vapour atomic absorption spectrometry is described. The method uses a typical flow-injection manifold where digestion and reduction of the injected sample takes place. Mercury is removed by aeration from the flowing stream in a specially designed air-liquid separator and swept into a silica cell for absorption measurement at a wavelength of 253.7 nm. A calibration curve up to 10 μg Hg ml-1 using three different path length cells is obtained with a detection limit of 0.02 μg Hg ml-1. The sampling rate of an injection every 3 min produces 20 results per hour from a flowing stream. PMID:18925201

  14. Asymptotic and numerical analysis of electrohydrodynamic flows of dielectric liquid.

    PubMed

    Suh, Y K; Baek, K H; Cho, D S

    2013-08-01

    We perform an asymptotic analysis of electrohydrodynamic (EHD) flow of nonpolar liquid subjected to an external, nonuniform electric field. The domain of interest covers the bulk as well as the thin dissociation layers (DSLs) near the electrodes. Outer (i.e., bulk) equations for the ion transport in hierarchical order of perturbation parameters can be expressed in linear form, whereas the inner (i.e., DSL) equations take a nonlinear form. We derive a simple formula in terms of various parameters which can be used to estimate the relative importance of the DSL-driven flow compared with the bulk-driven flow. EHD flow over a pair of cylindrical electrodes is then solved asymptotically and numerically. It is found that in large geometric scale and high ion concentration the EHD flow is dominated by the bulk-charge-induced flow. As the scale and concentration are decreased, the DSL-driven slip velocity increases and the resultant flow tends to dominate the domain and finally leads to flow reversal. We also conduct a flow-visualization experiment to verify the analysis and attain good agreement between the two results with parameter tuning. We finally show, based on the comparison of experimental and numerical solutions, that the rate of free-ion generation (dissociation) should be less than the one predicted from the existing formula. PMID:24032920

  15. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, Charles C.; Taylor, Larry T.

    1986-01-01

    A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  16. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    DOEpatents

    Johnson, C.C.; Taylor, L.T.

    1985-01-04

    A zero dead volume (ZDV) microbore high performance liquid chromatography (..mu.. HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a ..mu.. HPLC column end fitting to minimize the transfer volume of the effluents exiting the ..mu.. HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF/sub 2/), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  17. Determination of maduramicin by liquid chromatography with atomic absorption spectrometric detection.

    PubMed

    Johnson, N A

    1989-01-01

    A liquid chromatograph was interfaced to an atomic absorption spectrometer for the detection and quantitation of maduramicin in feed matrixes at the 1-8 ppm level. Ionophores in general form strong 1:1 products with various metal cations, yielding complexes that are insoluble in water but very soluble in organic solvents. Maduramicin, a carboxylic, polyalcohol, polyether antibiotic, is labeled with the sodium cation and analyzed by atomic absorption spectroscopy (AAS). The lower limit of detection is approximately 100-200 ng maduramicin sodium salt. Feeds containing 1-8 ppm maduramicin are extracted with acetone, the extract is passed through an alumina column, the column is eluted with acetonitrile-water (90 + 10), and the eluate is analyzed for maduramicin by liquid chromatography-AAS after concentration and conversion of maduramicin to the sodium salt. Recoveries of maduramicin averaged 89.5%. Liquid chromatography with AAS detection has been shown to be a sensitive and highly specific technique for the determination of ionophores in general and maduramicin in particular. PMID:2708270

  18. Study of interfacial behavior in cocurrent gas-liquid flows

    SciTech Connect

    McCready, M.J.

    1990-01-01

    We have examined the mechanism of formation of solitary waves on gas-liquid flows and found, that these form from existing periodic waves which have sufficiently large ({approximately}1.5 to 2 depending upon fluid properties) amplitude to liquid layer-thickness ratios. The exact process for the wave shape change is not understood but it does not seem to be related to the wave steepness (amplitude/wavelength) or to separation of gas flow over the waves. The observed confinement of solitary waves to low liquid Reynolds numbers results because the necessary large precursor waves do not form if the wave speed dispersion is too large or if the wavelength of the dominant waves is too short, as occurs for higher Re{sub L}. Measurements of interface tracings and calculations of power spectra and bispectra as a function of flow distance for conditions close to neutral stability reveal that the initially, linearly unstable mode is stabilized by formation of overtones which are linearly stable and can dissipate energy. As a result, a stable wave field can occur. Mode equations, which include quadratic nonlinearities, can model this process to the extent of producing some degree of quantitative predictions for the amplitudes of the wave modes. However, a complete picture of the wave field must include sidebands as well because these are observed for some flow conditions. 34 refs., 12 figs., 2 tabs.

  19. Transition of Thermocapillary Flow in Low Prandtl Number Liquid Bridge

    NASA Astrophysics Data System (ADS)

    Sasaki, Hiroei; Matsumoto, Satoshi; Yoda, Erika; Imaishi, Nobuyuki; Yoda, Shinichi

    2005-11-01

    An experimental study of thermocapillary convection in the half-zone liquid bridge of low Prandtl number fluid was performed to observe the transition behavior from steady to oscillatory flows. In thermocapillary convection, one of the still open problems is the observation of onset of oscillatory flow in low Prandtl number fluids. Numerical simulations predicted that there would be two transition points which were a first and second critical Marangoni number (Mac1 and Mac2). However, an experimental verification has not been performed previously because of its difficulties. A molten tin was used as test fluid and a liquid bridge configuration was employed. The temperature distribution at the interface between the liquid bridge and the cold disk was measured by using several fine thermocouples. It could be experimentally detected that the axisymmetric steady flow changes to three-dimensional steady one with increasing the temperature difference. At higher temperature difference, onset of oscillatory flow was also observed. Experimental results concerning the critical Marangoni numbers agreed very well with numerical simulation.

  20. Optical Feedback Interferometry for Velocity Measurement of Parallel Liquid-Liquid Flows in a Microchannel.

    PubMed

    Ramírez-Miquet, Evelio E; Perchoux, Julien; Loubière, Karine; Tronche, Clément; Prat, Laurent; Sotolongo-Costa, Oscar

    2016-01-01

    Optical feedback interferometry (OFI) is a compact sensing technique with recent implementation for flow measurements in microchannels. We propose implementing OFI for the analysis at the microscale of multiphase flows starting with the case of parallel flows of two immiscible fluids. The velocity profiles in each phase were measured and the interface location estimated for several operating conditions. To the authors knowledge, this sensing technique is applied here for the first time to multiphase flows. Theoretical profiles issued from a model based on the Couette viscous flow approximation reproduce fairly well the experimental results. The sensing system and the analysis presented here provide a new tool for studying more complex interactions between immiscible fluids (such as liquid droplets flowing in a microchannel). PMID:27527178

  1. Intestinal absorption of dietary fat from a liquid diet perfused in rats at a submaximum level

    SciTech Connect

    Simko, V.; Kelley, R.E.

    1988-02-01

    The small intestine of rats was perfused in vivo for 2 h with a nutritionally complete liquid diet (68% calories from fat as corn oil). As the perfusion increased from 106 mg/2 h, the intestinal disappearance of the /sup 14/C-triolein marker remained proportional to the load up to 2359 mg fat/2 h. Despite a decrease in absorption from 70 to 17%, this represents a very large fat intake. Fat absorption improved when medium-chain triglycerides or octanoic acid replaced corn oil (both p less than 0.01). Linoleic acid was absorbed from the diet less than corn oil (p less than 0.01). Dry ox bile reduced fat absorption (p less than 0.05); lipase and an antacid had no effect. Corn oil perfused alone was absorbed better than from the diet (p less than 0.01). Data with /sup 14/C-triolein was confirmed by dry-weight disappearance of the diet and by net intestinal water balance. Usual feeding underutilizes a large reserve for fat absorption. This reserve should be considered in therapeutic nutrition.

  2. Determining CDOM Absorption Spectra in Diverse Aquatic Environments Using a Multiple Pathlength, Liquid Core Waveguide System

    NASA Technical Reports Server (NTRS)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2001-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, aCDOM, and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values and showed a linear response across all four pathlengths. Values of aCDOM measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of aCDOM for MPLCW measurements was 0.002 - 231.5 m-1. At low CDOM concentrations spectrophotometric aCDOM were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples.

  3. Two-dimensional ultrasound Doppler velocimeter for flow mapping of unsteady liquid metal flows.

    PubMed

    Franke, S; Lieske, H; Fischer, A; Büttner, L; Czarske, J; Räbiger, D; Eckert, S

    2013-03-01

    We present a novel pulsed-wave ultrasound Doppler system for fluid flow investigations being able to determine two-dimensional vector fields of flow velocities. Electromagnetically-driven liquid metal flows appear as an attractive application field for such a measurement system. Two linear ultrasound transducer arrays each equipped with 25 transducer elements are used to measure the flow field in a square plane of 67×67 mm(2). The application of advanced processing methods as a multi-beam operation, an interlaced echo signal acquisition and a segmental array technique enable high data acquisition rates and concurrently a high spatial resolution, which have not been obtained so far for flow measurements in liquid metals. The extended pulsing strategy and essential operation principles such as the multiplexing electronic concept will be presented within this paper. The capabilities of the measuring system make it suitable for investigations of non-transparent, turbulent flows. Here, we present measurements of liquid metal flows driven by a rotating magnetic field for demonstration purposes. The measuring setup realized here reveals details of the swirling fluid motion in a horizontal section of a cube. Frame acquisition rates up to 30 fps were achieved for a complete two-dimensional flow mapping. PMID:23186828

  4. Mechanism of magnetic liquid flowing in the magnetic liquid seal gap of reciprocating shaft

    NASA Astrophysics Data System (ADS)

    Li, Decai; Xu, Haiping; He, Xinzhi; Lan, Huiqing

    2005-03-01

    In order to solve the problems that exist in the magnetic liquid seal of reciprocating shaft, we have set up an experimental facility, which composes a camera, microscope, step-by-step motor, pin roller screw, reciprocating motion shaft, pole pieces, permanent magnet and the magnetic liquid in the seal gap. Through the optical technology and image process of the experimental facility, we have studied the magnetic liquid flow in the seal gap when the reciprocating shaft moves with different velocities and strokes. This study specially concentrates on: (1) the regular pattern of such flow; (2) the loss quantity of magnetic liquid caused by the reciprocating motion shaft; (3) the failure reasons of this magnetic liquid seal; and (4) the design of a new structure for the magnetic liquid seal of reciprocating shaft. The application indicates that the new structure is very effective in some occasions. The new structure was accepted as the state patent in 2001 and authenticated as the achievement in the scientific research in 2002.

  5. Low-gravity sensing of liquid/vapor interface and transient liquid flow

    NASA Astrophysics Data System (ADS)

    Jacobson, Saul A.; Korba, James M.; Lynnworth, Lawrence C.; Nguyen, Toan H.; Orton, George F.

    1987-03-01

    The work reported here deals mainly with tests on internally vaned cylindrical shell acrylic containers capped by hemispherical acrylic or aluminum end domes. Three different ultrasonic sensor techniques and one nucleonic technique presently are evaluated as possible solutions to the low-gravity liquid gauging problem. The ultrasonic techniques are as follows: use of a torsional wave sensor in which transit time is proportional to the integral of wetted distance x liquid density; integration of the flow rate output signal of a fast-response ultrasonic flowmeter; and use of multiplexed externally mounted 'point-sensor' transducers that sense transit times to liquid-gas interfaces. Using two commercial flowmeters and a thickness gauge modified for this particular project, bench tests were conducted at 1 g on liquids such as water, freon, and solvent 140, including both steady flow and pulsating flow with 40, 80, and 120 ms flow pulses. Subsequently, flight tests were conducted in the NASA KC-135 aircraft in which nearly 0-g conditions are obtainable for up to about 5 s in each of a number of repetitive parabolic flight trajectories. In some of these brief low-gravity flight tests freon was replaced with a higher-viscosity fuel to reduce sloshing and thereby obtain settled surfaces more quickly.

  6. Nonlinear flow behaviors of nematic liquid crystals in complex geometries

    NASA Astrophysics Data System (ADS)

    Araki, Takeaki

    2013-02-01

    We study nematic liquid crystals flowing in a regular-shaped porous medium by means of lattice Boltzmann simulations. With strong anchoring, the director field cannot align uniformly and topological defects are stably formed with a large number of possible configurations. In a quiescent state, each configuration is arrested since the energy barriers between possible configurations are higher than the thermal energy. If the flow speed is slow enough, the defect pattern is not changed from the initial quiescent configuration. Above a critical flow speed, the defect pattern transforms to a new stable configuration. In a regular-shaped porous matrix, there remain regularly aligned disclination loops. This regular pattern is maintained even after the flow is stopped.

  7. Standard Flow Liquid Chromatography for Shotgun Proteomics in Bioenergy Research

    PubMed Central

    González Fernández-Niño, Susana M.; Smith-Moritz, A. Michelle; Chan, Leanne Jade G.; Adams, Paul D.; Heazlewood, Joshua L.; Petzold, Christopher J.

    2015-01-01

    Over the past 10 years, the bioenergy field has realized significant achievements that have encouraged many follow on efforts centered on biosynthetic production of fuel-like compounds. Key to the success of these efforts has been transformational developments in feedstock characterization and metabolic engineering of biofuel-producing microbes. Lagging far behind these advancements are analytical methods to characterize and quantify systems of interest to the bioenergy field. In particular, the utilization of proteomics, while valuable for identifying novel enzymes and diagnosing problems associated with biofuel-producing microbes, is limited by a lack of robustness and limited throughput. Nano-flow liquid chromatography coupled to high-mass accuracy, high-resolution mass spectrometers has become the dominant approach for the analysis of complex proteomic samples, yet such assays still require dedicated experts for data acquisition, analysis, and instrument upkeep. The recent adoption of standard flow chromatography (ca. 0.5 mL/min) for targeted proteomics has highlighted the robust nature and increased throughput of this approach for sample analysis. Consequently, we assessed the applicability of standard flow liquid chromatography for shotgun proteomics using samples from Escherichia coli and Arabidopsis thaliana, organisms commonly used as model systems for lignocellulosic biofuels research. Employing 120 min gradients with standard flow chromatography, we were able to routinely identify nearly 800 proteins from E. coli samples; while for samples from Arabidopsis, over 1,000 proteins could be reliably identified. An examination of identified peptides indicated that the method was suitable for reproducible applications in shotgun proteomics. Standard flow liquid chromatography for shotgun proteomics provides a robust approach for the analysis of complex samples. To the best of our knowledge, this study represents the first attempt to validate the standard

  8. Sound Absorption of a 2DOF Resonant Liner with Negative Bias Flow

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Cataldi, P.; Gaeta, R. J., Jr.

    2000-01-01

    This report describes an experimental study conducted to determine the effect of negative bias flow on the sound absorption of a two degree-of-freedom liner. The backwall for the liner was designed to act as a double-Helmholtz resonator so as to act as a hard wall at all frequencies except at its resonant frequencies. The effect of bias flow is investigated for a buried septum porosity of 2% and 19.5% for bias flow orifice Mach numbers up to 0.311. The bias flow appears to modify the resistance and reactance of the backwall alone at lower frequencies up to about 2 kHz, with marginal effects at higher frequencies. Absorption coefficients close to unity are achieved for a frequency range of 500 - 4000 Hz for the overall liner for a septum porosity of 2% and orifice Mach number of 0.128. Insertion loss tests performed in a flow duct facility for grazing flow Mach numbers up to 0.2 and septum Mach numbers up to 0.15 showed that negative bias flow can increase insertion loss by as much as 10 dB at frequencies in the range of 500 D 1400 Hz compared to no grazing flow. The effectiveness of the negative bias flow is diminished as the grazing flow velocity is increased.

  9. Real-time precision concentration measurement for flowing liquid solutions

    NASA Astrophysics Data System (ADS)

    Krishna, V.; Fan, C. H.; Longtin, J. P.

    2000-10-01

    The precise, real-time measurement of liquid concentration is important in fundamental research, chemical analysis, mixing processes, and manufacturing, e.g., in the food and semiconductor industries. This work presents a laser-based, noninvasive technique to measure concentration changes of flowing liquids in real time. The essential components in the system include a 5 mW laser diode coupled to a single-mode optical fiber, a triangular optical cell, and a high-resolution beam position sensor. The instrument provides a large range of concentration measurement, typically 0%-100% for binary liquid mixtures, while providing a resolution on the order of 0.05% concentration or better. The experimental configuration is small, reliable, and inexpensive. Results are presented for NaCl and MgCl2 aqueous solutions with concentrations ranging from 0% to 25%, with very good agreement found between measured and true concentrations.

  10. Flow Straightener for a Rotating-Drum Liquid Separator

    NASA Technical Reports Server (NTRS)

    O'Coin, James R.; Converse, David G.; Rethke, Donald W.

    2004-01-01

    A flow straightener has been incorporated into a rotary liquid separator that originally comprised an inlet tube, a shroud plate, an impeller, an inner drum, an outer drum, a housing, a pitot tube, and a hollow shaft motor. As a consequence of the original geometry of the impeller, shroud, inner drum, and hollow shaft, swirl was created in the airflow inside the hollow shaft during operation. The swirl speed was large enough to cause a significant pressure drop. The flow straightener consists of vanes on the back side of the shroud plate. These vanes compartmentalize the inside of the inner drum in such a way as to break up the flow path and thereby stop the air from swirling; as a result, the air enters the hollow shaft with a predominantly axial velocity instead of a swirl. Tests of the rotary liquid separator at an airflow rate of 10 cu ft/min (0.0047 cu m/s) revealed that the dynamic pressure drop was 8 in. of water (approx.=2 kPa) in the absence of the flow straightener and was reduced to 1 in. of water (approx.=0.25 kPa) in the presence of the flow straightener.

  11. Orientational dynamics of nematic liquid crystals under shear flow

    NASA Astrophysics Data System (ADS)

    Rienäcker, G.; Hess, S.

    The orientational dynamics of low molecular weight and polymeric nematic liquid crystals in a flow field is investigated, based on a nonlinear relaxation equation for the second rank alignment tensor. Various approximations are discussed: Assuming uniaxial alignment with a constant order parameter, the results of the Ericksen-Leslie theory are recovered. The detailed analysis to be presented here for plane Couette flow concerns (i) uniaxial alignment with a variable degree of order and (ii) the tensorial analysis involving the three symmetry-adapted components of the five components of the alignment tensor. The transitions between tumbling, wagging and aligning behavior observed in polymeric liquid crystals and described by the Doi theory of rod-like nematic polymers are recovered. Consequences for the rheological behavior are indicated.

  12. Viscoelastic Flows in Simple Liquids Generated by Vibrating Nanostructures

    NASA Astrophysics Data System (ADS)

    Pelton, Matthew; Chakraborty, Debadi; Malachosky, Edward; Guyot-Sionnest, Philippe; Sader, John E.

    2013-12-01

    Newtonian fluid mechanics, in which the shear stress is proportional to the strain rate, is synonymous with the flow of simple liquids such as water. We report the measurement and theoretical verification of non-Newtonian, viscoelastic flow phenomena produced by the high-frequency (20 GHz) vibration of gold nanoparticles immersed in water-glycerol mixtures. The observed viscoelasticity is not due to molecular confinement, but is a bulk continuum effect arising from the short time scale of vibration. This represents the first direct mechanical measurement of the intrinsic viscoelastic properties of simple bulk liquids, and opens a new paradigm for understanding extremely high frequency fluid mechanics, nanoscale sensing technologies, and biophysical processes.

  13. Electron bubbles in liquid helium: Density functional calculations of infrared absorption spectra

    SciTech Connect

    Grau, Victor; Barranco, Manuel; Mayol, Ricardo; Pi, Marti

    2006-02-01

    Within density functional theory, we have calculated the energy of the transitions from the ground state to the first two excited states in the electron bubbles in liquid helium at pressures from zero to about the solidification pressure. For {sup 4}He at low temperatures, our results are in very good agreement with infrared absorption experiments. Above a temperature of {approx}2 K, we overestimate the energy of the 1s-1p transition. We attribute this to the break down of the Franck-Condon principle due to the presence of helium vapor inside the bubble. Our results indicate that the 1s-2p transition energies are sensitive not only to the size of the electron bubble, but also to its surface thickness. We also present results for the infrared transitions in the case of liquid {sup 3}He, for which we lack experimental data.

  14. Development of cellular absorptive tracers (CATs) for a quantitative characterization of microbial mass in flow systems.

    PubMed

    Choi, Jaeyoung; Saripalli, Prasad; Meldrum, Deirdre; Lee, Ju Young

    2007-12-01

    A new method was developed for a simple non-destructive characterization of bacterial mass in flow systems. Results of partition and transport experiments showed that adsorption of a CAT molecule into the cellular mass resulted in its retardation during flow, which was a good measure of the biomass quantity and distribution. Three dyes, acridine orange (AO), toluidine blue (TB), and safranin O (SO), were chosen as CATs to demonstrate their utility to quantitatively characterize the biomass, its location and morphology in flow system. The results clearly demonstrated the applicability of AO, TB, and SO as cellular absorptive tracers in columnar flow experiments. PMID:17329099

  15. Modeling of Liquid Flow in a Packed Bed in the Presence of Gas Flow

    NASA Astrophysics Data System (ADS)

    Singh, V.; Gupta, G. S.; Sarkar, S.

    2007-06-01

    Liquid metal and slag descend through a porous coke matrix in the lower part of an iron making blast furnace. The size of the raceway is an important factor in determining the gas penetration into the bed, which pushes the liquid toward the deadman region. This, in turn, affects the gas flow in the bed. The current study tries to explain theoretically the effect of cavity size hysteresis on gas-liquid distribution in a packed bed. The liquid flow has been modeled considering it to be discrete in nature. The turbulent nature of gas flow has been modeled using the k-ɛ model for turbulent flow. The model results have been verified on a structured package. It is observed that the liquid is pushed away further from the nozzle-side wall in the case of decreasing gas velocity than increasing gas velocity at the same inlet gas velocity. The implications of the current study to the dropping zone of a blast furnace have been discussed.

  16. Progress in Creating Stabilized Gas Layers in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Felde, David K; Riemer, Bernie; Abdou, Ashraf A; D'Urso, Brian R; West, David L

    2009-01-01

    The Spallation Neutron Source (SNS) facility in Oak Ridge, Tennessee uses a liquid mercury target that is bombarded with protons to produce a pulsed neutron beam for materials research and development. In order to mitigate expected cavitation damage erosion (CDE) of the containment vessel, a two-phase flow arrangement of the target has been proposed and was earlier proven to be effective in significantly reducing CDE in non-prototypical target bodies. This arrangement involves covering the beam "window", through which the high-energy proton beam passes, with a protective layer of gas. The difficulty lies in establishing a stable gas/liquid interface that is oriented vertically with the window and holds up to the strong buoyancy force and the turbulent mercury flow field. Three approaches to establishing the gas wall have been investigated in isothermal mercury/gas testing on a prototypical geometry and flow: (1) free gas layer approach, (2) porous wall approach, and (3) surface-modified approach. The latter two of these approaches show success in that a stabilized gas layer is produced. Both of these successful approaches capitalize on the high surface energy of liquid mercury by increasing the surface area of the solid wall, thus increasing gas hold up at the wall. In this paper, a summary of these experiments and findings is presented as well as a description of the path forward toward incorporating the stabilized gas layer approach into a feasible gas/mercury SNS target design.

  17. Method and apparatus for measuring coupled flow, transport, and reaction processes under liquid unsaturated flow conditions

    DOEpatents

    McGrail, Bernard P.; Martin, Paul F.; Lindenmeier, Clark W.

    1999-01-01

    The present invention is a method and apparatus for measuring coupled flow, transport and reaction processes under liquid unsaturated flow conditions. The method and apparatus of the present invention permit distinguishing individual precipitation events and their effect on dissolution behavior isolated to the specific event. The present invention is especially useful for dynamically measuring hydraulic parameters when a chemical reaction occurs between a particulate material and either liquid or gas (e.g. air) or both, causing precipitation that changes the pore structure of the test material.

  18. Annular Flow Liquid Film Dynamics in Pipes and Bod Bundle

    NASA Astrophysics Data System (ADS)

    Ju, Peng

    Average liquid film thickness is important for detailed mechanistic modeling of annular two-phase flow in engineering applications. The existing models and correlations either have large relative errors or narrow application range. Because of this, a new liquid film thickness model has been developed for vertical annular flow in pipes based on three databases. The model includes the pressure, liquid and gas velocities, diameter, and viscosity effects on liquid film thickness. Analysis indicates the film thickness to be a function of Weber numbers for both liquid and gas, and the viscosity number. The model is compared with film thickness data which considers a wide range of liquid and gas superficial velocities, system pressure, fluid properties, as well as several pipe diameters. The trend in the current and available film thickness models at various system conditions are analyzed, highlighting the improvement and widening applicability of the new model. The newly proposed film thickness model results in an average relative error of 14% considering the complete database. Interfacial friction factor in annular two-phase flow is essential both for detailed modeling of two-fluid model and the calculation of pressure gradient. Most of the existing correlations on interfacial friction factor are based on Wallis 1969's correlation, which considers the interfacial friction factor as a function of film thickness. In this research, a new correlation of interfacial friction factor that is based on the wave characteristics has been proposed. The wave characteristics is considered to be a function of a group of non-dimensional numbers. Since the effects of wave characteristics for ripples waves and disturbance waves on interfacial friction factors are different, the correlation is divided into two sub-correlations based on these two wave regimes. The new correlation has been compared with a wide range of data. From the data comparison, the new correlation shows significant

  19. Flow characteristics of a partially submerged liquid pickup. Final report

    SciTech Connect

    Bartz D.

    1984-02-17

    Biphase Energy Systems has been developing the technology for two-phase power production. The Biphase turbine is a state-of-the-art two-phase turbine with many potential advantages, including low cost, high efficiency, high torque, and simplicity: The potential exists for substantial performance improvements. This report concludes the third phase of a three-part program funded by the DOE to study energy transfer processes associated with two-phase turbine operation. Figure I-1 shows a schematic of the impulse version of the two-phase turbine. A liquid-gas mixture enters the turbine through the inlet two-phase nozzle. The first energy transfer process occurs here where the mixture expands through the nozzle, converting pressure and thermal energy into flow kinetic energy at the nozzle discharge. Phase I of the progeam determined experimentally the efficiency of the nozzle expansion process. The two-phase jets departing the nozzles impinge on the inner surface of a rotating separator. Here the flow exerts a torque on the separator, which may be used as a drag turbine to convert the flow's kinetic energy into mechanical shaft power. A measure of the momentum transfer from the nozzle exit jet to the rotary separator, defined as torque ratio, was determined. Alternatively, the liquid in the separator may be collected by a stationary diffuser. In this case the liquid kinetic energy is converted to pressure energy by means of momentum diffusion as the flow velocity decreases in a diverging section of diffuser. Phase III of the program examines the characteristics of these enegy conversion processes. In particular, mechanical energy losses associated with external drag, after body wake and spray, and the internal flow losses are predicted and measured.

  20. Development of Cellular Absorptive Tracers (CATs) for a Quantitative Characterization of Microbial Mass in Flow Systems

    SciTech Connect

    Saripalli, Prasad; Brown, Christopher F.; Lindberg, Michael J.

    2005-03-16

    We report on a new Cellular Absorptive Tracers (CATs) method, for a simple, non-destructive characterization of bacterial mass in flow systems. Results show that adsorption of a CAT molecule into the cellular mass results in its retardation during flow, which is a good, quantitative measure of the biomass quantity and distribution. No such methods are currently available for a quantitative characterization of cell mass.

  1. UV/VIS liquid-core optical fiber long lightpath absorption system for spectrophotometer

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Wu, Guanyan; Xu, Zheng; Liao, Yuanmin; He, Qushe; Wang, Jufang; Feng, Mingzhao

    1998-08-01

    A new type of UV/VIS liquid-core optical fiber long lightpath absorption system, which was designed as an accessory and spectrum range was extended to UV with minimum wavelength 220 micrometer to compatible with conventional UV/VIS spectrophotometer, was described with high assembling precision RSD 1.4% and absorption 1 to approximately 700 cm for choice. The coupling between source light radiation and liquid-core optical fiber was tested and optimum condition was obtained. The samples introduction was presented and UV transmission spectra of optical fiber was detected. The system was applied to detect elements Cd(II), Pd(II), F-1, Cr(VI), Cu(II), Fe(II), Ti(IV), Pt(II) and medicines Carbamazipine and Vitamin E by using of 105 cm long LCOF, and sensitivities were 42 to approximately 158 times as much as those by 1 cm conventional cell in length, detection limits (3(sigma) ) 0.14 to approximately 17 ng/ml, relative errors less than 11.2%, and recoveries 94 to approximately 102%.

  2. Calibration of scattering and absorption properties of a liquid diffusive medium at NIR wavelengths. CW method.

    PubMed

    Martelli, Fabrizio; Zaccanti, Giovanni

    2007-01-22

    In spite of many progresses achieved both with theories and with experiments in studying light propagation through diffusive media, a reliable method for accurate measurements of the optical properties of diffusive media at NIR wavelengths is, in our opinion, still missing. It is therefore difficult to create a diffusive medium with well known optical properties to be used as a reference. In this paper we describe a method to calibrate the reduced scattering coefficient, mu'(s) , of a liquid diffusive medium and the absorption coefficient, mu(a), of an absorbing medium with a standard error smaller than 2% both on mu'(s) and on mu(a). The method is based on multidistance measurements of fluence into an infinite medium illuminated by a CW source. The optical properties are retrieved with simple inversion procedures (linear fits) exploiting the knowledge of the absorption coefficient of the liquid into which the diffuser and the absorber are dispersed. In this study Intralipid diluted in water has been used as diffusive medium and Indian ink as absorber. For a full characterization of these media measurements of collimated transmittance have also been carried out, from which the asymmetry factor of the scattering function of Intralipid and the single scattering albedo of Indian ink have been determined. PMID:19532267

  3. Liquid Droplet Detachment and Entrainment in Microscale Flows

    NASA Astrophysics Data System (ADS)

    Hidrovo, Carlos

    2005-11-01

    In this talk we will present a first order study of liquid water detachment and entrainment into air flows in hydrophobic microchannels. Silicon based microstructures consisting of 23 mm long U-shaped channels of different geometry were used for this purpose. The structures are treated with a Molecular Vapor Deposition (MVD) process that renders them hydrophobic. Liquid water is injected through a side slot located 2/3 of the way downstream from the air channel inlet. The water entering the air channel beads up into slugs or droplets that grow in size at this injection location until they fill and flood the channel or are carried away by the air flow. The slugs/droplets dimensions at detachment are correlated against superficial gas velocity and proper dimensionless parameters are postulated and examined to compare hydrodynamic forces against surface tension. It is found that slug/droplet detachment is dominated by two main forces: pressure gradient drag, arising from confinement of a viscous flow in the channel, and inertial drag, arising from the stagnation of the air due to obstruction by the slugs/droplets. A detachment regime map is postulated based on the relative importance of these forces under different flow conditions.

  4. Impact of droplets on inclined flowing liquid films.

    PubMed

    Che, Zhizhao; Deygas, Amandine; Matar, Omar K

    2015-08-01

    The impact of droplets on an inclined falling liquid film is studied experimentally using high-speed imaging. The falling film is created on a flat substrate with controllable thicknesses and flow rates. Droplets with different sizes and speeds are used to study the impact process under various Ohnesorge and Weber numbers, and film Reynolds numbers. A number of phenomena associated with droplet impact are identified and analyzed, such as bouncing, partial coalescence, total coalescence, and splashing. The effects of droplet size, speed, as well the film flow rate are studied culminating in the generation of an impact regime map. The analysis of the lubrication force acted on the droplet via the gas layer shows that a higher flow rate in the liquid film produces a larger lubrication force, slows down the drainage process, and increases the probability of droplet bouncing. Our results demonstrate that the flowing film has a profound effect on the droplet impact process and associated phenomena, which are markedly more complex than those accompanying impact on initially quiescent films. PMID:26382528

  5. Dispersive Liquid-Liquid Microextraction of Bismuth in Various Samples and Determination by Flame Atomic Absorption Spectrometry.

    PubMed

    Daşbaşı, Teslima; Kartal, Şenol; Saçmacı, Şerife; Ülgen, Ahmet

    2016-01-01

    A dispersive liquid-liquid microextraction method for the determination of bismuth in various samples by flame atomic absorption spectrometry is described. In this method, crystal violet was used as counter positive ion for BiCl4 (-) complex ion, chloroform as extraction solvent, and ethanol as disperser solvent. The analytical parameters that may affect the extraction efficiency like acidity of sample, type and amount of extraction and disperser solvents, amount of ligand, and extraction time were studied in detail. The effect of interfering ions on the analyte recovery was also investigated. The calibration graph was linear in the range of 0.040-1.00 mg L(-1) with detection limit of 4.0 μg L(-1) (n = 13). The precision as relative standard deviation was 3% (n = 11, 0.20 mg L(-1)) and the enrichment factor was 74. The developed method was applied successfully for the determination of bismuth in various water, pharmaceutical, and cosmetic samples and the certified reference material (TMDA-64 lake water). PMID:26881186

  6. Dispersive Liquid-Liquid Microextraction of Bismuth in Various Samples and Determination by Flame Atomic Absorption Spectrometry

    PubMed Central

    Daşbaşı, Teslima; Kartal, Şenol; Saçmacı, Şerife; Ülgen, Ahmet

    2016-01-01

    A dispersive liquid-liquid microextraction method for the determination of bismuth in various samples by flame atomic absorption spectrometry is described. In this method, crystal violet was used as counter positive ion for BiCl4− complex ion, chloroform as extraction solvent, and ethanol as disperser solvent. The analytical parameters that may affect the extraction efficiency like acidity of sample, type and amount of extraction and disperser solvents, amount of ligand, and extraction time were studied in detail. The effect of interfering ions on the analyte recovery was also investigated. The calibration graph was linear in the range of 0.040–1.00 mg L−1 with detection limit of 4.0 μg L−1 (n = 13). The precision as relative standard deviation was 3% (n = 11, 0.20 mg L−1) and the enrichment factor was 74. The developed method was applied successfully for the determination of bismuth in various water, pharmaceutical, and cosmetic samples and the certified reference material (TMDA-64 lake water). PMID:26881186

  7. The Three-D Flow Structures of Gas and Liquid Generated by a Spreading Flame Over Liquid Fuel

    NASA Technical Reports Server (NTRS)

    Tashtoush, G.; Ito, A.; Konishi, T.; Narumi, A.; Saito, K.; Cremers, C. J.

    1999-01-01

    We developed a new experimental technique called: Combined laser sheet particle tracking (LSPT) and laser holographic interferometry (HI), which is capable of measuring the transient behavior of three dimensional structures of temperature and flow both in liquid and gas phases. We applied this technique to a pulsating flame spread over n-butanol. We found a twin vortex flow both on the liquid surface and deep in the liquid a few mm below the surface and a twin vortex flow in the gas phase. The first twin vortex flow at the liquid surface was observed previously by NASA Lewis researchers, while the last two observations are new. These observations revealed that the convective flow structure ahead of the flame leading edge is three dimensional in nature and the pulsating spread is controlled by the convective flow of both liquid and gas.

  8. High Average Power Laser Gain Medium With Low Optical Distortion Using A Transverse Flowing Liquid Host

    DOEpatents

    Comaskey, Brian J.; Ault, Earl R.; Kuklo, Thomas C.

    2005-07-05

    A high average power, low optical distortion laser gain media is based on a flowing liquid media. A diode laser pumping device with tailored irradiance excites the laser active atom, ion or molecule within the liquid media. A laser active component of the liquid media exhibits energy storage times longer than or comparable to the thermal optical response time of the liquid. A circulation system that provides a closed loop for mixing and circulating the lasing liquid into and out of the optical cavity includes a pump, a diffuser, and a heat exchanger. A liquid flow gain cell includes flow straighteners and flow channel compression.

  9. Ergot alkaloids reduce rumen epithelial blood flow and volatile fatty acid absorption

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ergot alkaloids have been shown to induce vasoconstriction of both peripheral and ruminal vessels. Constriction of ruminal vessels could lead to a reduction in epithelial blood flow thereby reducing nutrient absorption. The objectives of this experiment were to determine if steers receiving endophyt...

  10. A handy liquid metal based electroosmotic flow pump.

    PubMed

    Gao, Meng; Gui, Lin

    2014-06-01

    A room temperature liquid metal based electroosmotic flow (EOF) pump has been proposed in this work. This low-cost EOF pump is convenient for both fabrication and integration. It utilizes polydimethylsiloxane (PDMS) microchannels filled with the liquid-metal as non-contact pump electrodes. The electrode channels are fabricated symmetrically to both sides of the pumping channel, having no contact with the pumping channel. To test the pumping performance of the EOF pump, the mean flow velocities of the fluid (DI water) in the EOF pumps were experimentally measured by tracing the fluorescent microparticles in the flow. To provide guidance for designing a low voltage EOF pump, parametric studies on dimensions of the electrode and pumping channels were performed in this work. According to the experimental results, the pumping speed can reach 5.93 μm s(-1) at a driving voltage of only 1.6 V, when the gap between the electrode and the pumping channel is 20 μm. Injecting a room temperature liquid metal into microchannels can provide a simple, rapid, low-cost but accurately self-aligned way to fabricate microelectrodes for EOF pumps, which is a promising method to achieve the miniaturization and integration of the EOF pump in microfluidic systems. The non-contact liquid electrodes have no influence on the fluid in the pumping channel when pumping, reducing Joule heat generation and preventing gas bubble formation at the surface of electrodes. The pump has great potential to drive a wide range of fluids, such as drug reagents, cell suspensions and biological macromolecule solutions. PMID:24706096

  11. Measuring absorption coefficient of scattering liquids using a tube inside an integrating sphere.

    PubMed

    Villanueva, Yolanda; Veenstra, Colin; Steenbergen, Wiendelt

    2016-04-10

    A method for measuring the absorption coefficient μa of absorbing and scattering liquid samples is presented. The sample is injected into a small transparent tube mounted through an integrating sphere. Two models for determining the absorption coefficient using the relative optical output signal are described and validated using aqueous ink absorbers of 0.5 vol.% (0.3  mm-1a<1.55  mm-1) and 1.0 vol.% (1.0  mm-1a<4.0  mm-1) concentrations with 1 vol.% (μs'≈1.4  mm-1) and 10 vol.% (μs'≈14  mm-1) Intralipid dilutions. The low concentrations give μa and μs values, which are comparable with those of biological tissues. One model assumes a uniform light distribution within the sample, which is valid for low absorption. Another model considers light attenuation that obeys Lambert-Beer's law, which may be used for relatively high absorption. Measurements with low and high scattering samples are done for the wavelength range of 400-900 nm. Measured spectra of purely absorbing samples are within 15% agreement with measurements using standard transmission spectrophotometry. For 0.5 vol.% ink absorbers and at wavelengths below 700 nm, measured μa values are higher for samples with low scattering and lower for those with high scattering. At wavelengths above 700 nm, measured μa values do not vary significantly with amount of scattering. For 1.0 vol.% ink absorbers, measured spectra do not change with low scattering. These results indicate that the method can be used for measuring absorption spectra of scattering liquid samples with optical properties similar to biological absorbers, particularly at wavelengths above 700 nm, which is difficult to accomplish with standard transmission spectrophotometry. PMID:27139871

  12. Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

    PubMed

    Hoche, S; Hussein, M A; Becker, T

    2015-03-01

    The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. PMID:25465962

  13. Bubble Generation in a Flowing Liquid Medium and Resulting Two-Phase Flow in Microgravity

    NASA Technical Reports Server (NTRS)

    Pais, S. C.; Kamotani, Y.; Bhunia, A.; Ostrach, S.

    1999-01-01

    The present investigation reports a study of bubble generation under reduced gravity conditions, using both a co-flow and a cross-flow configuration. This study may be used in the conceptual design of a space-based thermal management system. Ensuing two-phase flow void fraction can be accurately monitored using a single nozzle gas injection system within a continuous liquid flow conduit, as utilized in the present investigation. Accurate monitoring of void fraction leads to precise control of heat and mass transfer coefficients related to a thermal management system; hence providing an efficient and highly effective means of removing heat aboard spacecraft or space stations. Our experiments are performed in parabolic flight aboard the modified DC-9 Reduced Gravity Research Aircraft at NASA Lewis Research Center, using an air-water system. For the purpose of bubble dispersion in a flowing liquid, we use both a co-flow and a cross-flow configuration. In the co-flow geometry, air is introduced through a nozzle in the same direction with the liquid flow. On the other hand, in the cross-flow configuration, air is injected perpendicular to the direction of water flow, via a nozzle protruding inside the two-phase flow conduit. Three different flow conduit (pipe) diameters are used, namely, 1.27 cm, 1.9 cm and 2.54 cm. Two different ratios of nozzle to pipe diameter (D(sub N))sup * are considered, namely (D(sub N))sup * = 0.1 and 0.2, while superficial liquid velocities are varied from 8 to 70 cm/s depending on flow conduit diameter. It is experimentally observed that by holding all other flow conditions and geometry constant, generated bubbles decrease in size with increase in superficial liquid velocity. Detached bubble diameter is shown to increase with air injection nozzle diameter. Likewise, generated bubbles grow in size with increasing pipe diameter. Along the same lines, it is shown that bubble frequency of formation increases and hence the time to detachment of a

  14. Intermittency of rheological regimes in uniform liquid-granular flows.

    PubMed

    Armanini, Aronne; Larcher, Michele; Fraccarollo, Luigi

    2009-05-01

    We present a detailed analysis of a free surface-saturated liquid-granular mixture flowing over a static loose bed of grains, where the coexistence of layers dominated by collisional and frictional interactions among particles was observed. Kinetic theory was applied to the flow described above and it proved suitable for describing a realistic behavior of the collisional layers, although it failed to interpret the regions of the flow domain dominated by the frictional contacts. The paper provides a conceptual scheme with which to overcome this problem by focusing on the mechanisms governing the transition from the frictional to the collisional regime. In particular we observed that in highly concentrated flows the transition layer exhibits a typical intermittency of the dominating rheological regime, switching alternately from the frictional to the collisional one. By filtering the velocity signal, we introduced an intermittency function that made it possible to extend the validity of the equations derived from dense gas analogy, typical of the collisional regimes, also in the intermittent phase of the flow. Owing to the small values of the Stokes number, in the application of the kinetic theory we accounted for the possible variation of the elastic restitution coefficient along the flow depth. PMID:19518448

  15. Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometric for selenium speciation in foods and beverages.

    PubMed

    Tuzen, Mustafa; Pekiner, Ozlem Zeynep

    2015-12-01

    A rapid and environmentally friendly ultrasound assisted ionic liquid dispersive liquid liquid microextraction (USA-IL-DLLME) was developed for the speciation of inorganic selenium in beverages and total selenium in food samples by using graphite furnace atomic absorption spectrometry. Some analytical parameters including pH, amount of complexing agent, extraction time, volume of ionic liquid, sample volume, etc. were optimized. Matrix effects were also investigated. Enhancement factor (EF) and limit of detection (LOD) for Se(IV) were found to be 150 and 12 ng L(-1), respectively. The relative standard deviation (RSD) was found 4.2%. The accuracy of the method was confirmed with analysis of LGC 6010 Hard drinking water and NIST SRM 1573a Tomato leaves standard reference materials. Optimized method was applied to ice tea, soda and mineral water for the speciation of Se(IV) and Se(VI) and some food samples including beer, cow's milk, red wine, mixed fruit juice, date, apple, orange, grapefruit, egg and honey for the determination of total selenium. PMID:26041239

  16. Sound Absorption of a 2DOF Resonant Liner with Negative Bias Flow

    NASA Technical Reports Server (NTRS)

    Ahuja, K. K.; Cataldi, P.; Gaeta, R. J., Jr.; Jones, Mike (Technical Monitor)

    2000-01-01

    This report describes an experimental study conducted to determine the effect of negative bias flow on the sound absorption of a two degree-of-freedom liner. The backwall for the liner was designed to act as a double-Helmholtz resonator so as to act as a hard wall at all frequencies except at its resonant frequencies. All normal incident impedance data presented herein was acquired in an impedance tube. The effect of bias flow is investigated for a buried septum porosity of 2% and 19.5% for bias flow orifice mach numbers up to 03 11. As a porous backwall is needed for the flow to pass through, the effect of bias flow on this backwall all had to be evaluated first. The bias flow appears to modify the resistance and reactance of the backwall alone at lower frequencies up to about 2 kHz, with marginal effects at higher frequencies. Absorption coefficients close to unity are achieved for a frequency range of 500-4000 Hz for the overall liner for a septum porosity of 2% and orifice mach number of 0.128. Insertion loss tests performed in a flow duct facility for grazing flow Mach numbers up to 0.2 and septum mach numbers up to 0.15 showed that negative bias flow can increase insertion loss by as much as 10 dB at frequencies in the range of 500 - 1400 Hz compared to no grazing flow. The effectiveness of the negative bias flow is diminished as the grazing flow velocity is increased.

  17. Gas and liquid measurements in air-water bubbly flows

    SciTech Connect

    Zhou, X.; Doup, B.; Sun, X.

    2012-07-01

    Local measurements of gas- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)

  18. Anisotropic light absorption, refractive indices, and orientational order parameter of unidirectionally aligned columnar liquid crystal films.

    PubMed

    Charlet, Emilie; Grelet, Eric

    2008-10-01

    The anisotropic optical properties of thermotropic columnar liquid crystals absorbing in the visible range are investigated for different discotic compounds unidirectionally oriented in open supported thin films. Two methods to monitor the alignment of columnar mesophases in thin films are reported, making possible to achieve either homeotropic anchoring (columns normal to the substrate) by a specific thermal annealing, or unidirectional planar orientation (columns parallel to the substrate) by using a rubbed Teflon coating. The columnar liquid crystal anchoring is found to depend on the nature of the compound, either parallel or perpendicular to the Teflon orientation. Based on this control of the mesophase alignment, the dichroic ratio and the orientational order parameter of oriented samples are measured, and a high order parameter of 0.9 is found in the case of parallel alignment. From the polarized absorption data of the columnar liquid crystal films, the light wavelength dependence of the birefringence and of the real and imaginary parts (refractive index and extinction coefficient, respectively) of the anisotropic optical indices are determined over the whole visible range. PMID:18999445

  19. Versatile plug flow catalytic cell for in situ transmission/fluorescence x-ray absorption fine structure measurements

    NASA Astrophysics Data System (ADS)

    Centomo, P.; Meneghini, C.; Zecca, M.

    2013-05-01

    A novel flow-through catalytic cell has been developed for in situ x-ray absorption spectroscopy (XAS) experiments on heterogeneous catalysts under working conditions and in the presence of a liquid and a gas phase. The apparatus allows to carry out XAS measurements in both the transmission and fluorescence modes, at moderate temperature (from RT to 50-80 °C) and low-medium gas pressure (up to 7-8 bars). The materials employed are compatible with several chemicals such as those involved in the direct synthesis of hydrogen peroxide (O2, H2, H2O2, methanol). The versatile design of the cell allows to fit it to different experimental setups in synchrotron radiation beamlines. It was used successfully for the first time to test nanostructured Pd catalysts during the direct synthesis of hydrogen peroxide (H2O2) in methanol solution from dihydrogen and dioxygen.

  20. [Effects of carrier liquid and flow rate on the separation in gravitational field-flow fractionation].

    PubMed

    Guo, Shuang; Zhu, Chenqi; Gao-Yang, Yaya; Qiu, Bailing; Wu, Di; Liang, Qihui; He, Jiayuan; Han, Nanyin

    2016-02-01

    Gravitational field-flow fractionation is the simplest field-flow fractionation technique in terms of principle and operation. The earth' s gravity is its external field. Different sized particles are injected into a thin channel and carried by carrier fluid. The different velocities of the carrier liquid in different places results in a size-based separation. A gravitational field-flow fractionation (GrFFF) instrument was designed and constructed. Two kinds of polystyrene (PS) particles with different sizes (20 µm and 6 µm) were chosen as model particles. In this work, the separation of the sample was achieved by changing the concentration of NaN3, the percentage of mixed surfactant in the carrier liquid and the flow rate of carrier liquid. Six levels were set for each factor. The effects of these three factors on the retention ratio (R) and plate height (H) of the PS particles were investigated. It was found that R increased and H decreased with increasing particle size. On the other hand, the R and H increased with increasing flow rate. The R and H also increased with increasing NaN3 concentration. The reason was that the electrostatic repulsive force between the particles and the glass channel wall increased. The force allowed the samples approach closer to the channel wall. The results showed that the resolution and retention time can be improved by adjusting the experimental conditions. These results can provide important values to the further applications of GrFFF technique. PMID:27382718

  1. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    NASA Astrophysics Data System (ADS)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  2. Dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometry: ultra trace determination of cadmium in water samples.

    PubMed

    Zeini Jahromi, Elham; Bidari, Araz; Assadi, Yaghoub; Milani Hosseini, Mohammad Reza; Jamali, Mohammad Reza

    2007-03-01

    Dispersive liquid-liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 microL methanol (disperser solvent) containing 34 microL carbon tetrachloride (extraction solvent) and 0.00010 g ammonium pyrrolidine dithiocarbamate (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with ammonium pyrrolidine dithiocarbamate, and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25+/-1 microL). Then a 20 microL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 125 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the rage of 2-20 ng L(-1) with detection limit of 0.6 ng L(-1). The relative standard deviation (R.S.D.s) for ten replicate measurements of 20 ng L(-1) of cadmium was 3.5%. The relative recoveries of cadmium in tap, sea and rivers water samples at spiking level of 5 and 10 ng L(-1) are 108, 95, 87 and 98%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on-line liquid-liquid extraction, single drop microextraction (SDME), on-line solid phase extraction (SPE) and co-precipitation based on bibliographic data. Therefore, DLLME

  3. Rapid determination of lead in water samples by dispersive liquid-liquid microextraction coupled with electrothermal atomic absorption spectrometry.

    PubMed

    Naseri, Mohammad Taghi; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub; Kiani, Armin

    2008-03-15

    The need for highly reliable methods for the determination of trace and ultratrace elements has been recognized in analytical chemistry and environmental science. A simple and powerful microextraction technique was used for the detection of the lead ultratrace amounts in water samples using the dispersive liquid-liquid microextraction (DLLME), followed by the electrothermal atomic absorption spectrometry (ET AAS). In this microextraction technique, a mixture of 0.50 mL acetone (disperser solvent), containing 35 microL carbon tetrachloride (extraction solvent) and 5 microL diethyldithiophosphoric acid (chelating agent), was rapidly injected by syringe into the 5.00 mL water sample, spiked with lead. In this process, the lead ions reacted with the chelating agent and were extracted into the fine droplets of CCl(4). After centrifugation (2 min at 5000 rpm), the fine CCl4 droplets were sedimented at the bottom of the conical test tube (25+/-1 microL). Then, 20 microL from the sedimented phase, containing the enriched analyte, was determined by ET AAS. The next step was the optimization of various experimental conditions, affecting DLLME, such as the type and the volume of the extraction solvent, the type and the volume of the disperser solvent, the extraction time, the salt effect, pH and the chelating agent amount. Moreover, the effect of the interfering ions on the analytes recovery was also investigated. Under the optimum conditions, the enrichment factor of 150 was obtained from only a 5.00 mL water sample. The calibration graph was linear in the range of 0.05-1 microg L(-1) with the detection limit of 0.02 microg L(-1). The relative standard deviation (R.S.D.) for seven replicate measurements of 0.50 microg L(-1) of lead was 2.5%. The relative lead recoveries in mineral, tap, well and sea water samples at the spiking level of 0.20 and 0.40 microg L(-1) varied from 93.5 to 105.0. The characteristics of the proposed method were compared with the cloud point

  4. Mechanical annealing in the flow of supercooled metallic liquid

    SciTech Connect

    Zhang, Meng; Dai, Lan Hong; Liu, Lin

    2014-08-07

    Flow induced structural evolution in a supercooled metallic liquid Vit106a (Zr{sub 58.5}Cu{sub 15.6}Al{sub 10.3}Ni{sub 12.8}Nb{sub 2.8}, at. %) was investigated via uni-axial compression combined with differential scanning calorimeter (DSC). Compression tests at strain rates covering the transition from Newtonian flow to non-Newtonian flow and at the same strain rate 2 × 10{sup −1} s{sup −1} to different strains were performed at the end of glass transition (T{sub g-end} = 703 K). The relaxation enthalpies measured by DSC indicate that the samples underwent non-Newtonian flow contain more free volume than the thermally annealed sample (703 K, 4 min), while the samples underwent Newtonian flow contain less, namely, the free volume of supercooled metallic liquids increases in non-Newtonian flow, while decreases in Newtonian flow. The oscillated variation of the relaxation enthalpies of the samples deformed at the same strain rate 2 × 10{sup −1} s{sup −1} to different strains confirms that the decrease of free volume was caused by flow stress, i.e., “mechanical annealing.” Micro-hardness tests were also performed to show a similar structural evolution tendency. Based on the obtained results, the stress-temperature scaling in the glass transition of metallic glasses are supported experimentally, as stress plays a role similar to temperature in the creation and annihilation of free volume. In addition, a widening perspective angle on the glass transition of metallic glasses by exploring the 3-dimensional stress-temperature-enthalpy phase diagram is presented. The implications of the observed mechanical annealing effect on the amorphous structure and the work-hardening mechanism of metallic glasses are elucidated based on atomic level stress model.

  5. Visualization of diffuser outlet flow using liquid crystal sheets

    SciTech Connect

    Kirkpatrick, A.T.

    1995-08-01

    This article describes a new imaging technique to determine air temperatures and flow fields from HVAC diffusers. The technique uses liquid crystal sheets to record the airflow and temperatures in color. The air temperature field is an important contributor to the thermal comfort in a room and is used to evaluate diffuser performance. Visualization of the temperature field allows one to see directly the flow field and how it is interacting with the room air. a particular application is to cold-air distribution systems that supply cooling and ventilation air to rooms at temperatures lower than in conventional systems. In these systems the cold-air supply is as low as 39 F (4 C), instead of the conventional value of 55 F (13 C). This new technique uses a temperature-sensitive liquid crystal sheet to create a visual measuring tool. The liquid crystals are layered on a plane sheet and produce two-dimensional color images of the air temperature field. Since air is invisible, some type of indicator placed in the air stream is required to determine the air temperature. At present, instruments such as thermocouples and thermistors determine the air temperature in rooms and measure the value at a single point. Information about the temperature and flow field in a room is obtained by moving the device, or using multiple sensors. This is a time-consuming process, and only yields information at the points of measurement. However, the temperature field is usually unsteady, due to variable air currents and cooling loads, so a movable device is not entirely suitable, and multiple instruments require multiple data acquisition channels. It would be more informative to visualize the entire airflow from the diffuser at any instant. This article deals with a temperature characterization method.

  6. Optimizing the flow in a liquid sodium dynamo experiment

    NASA Astrophysics Data System (ADS)

    Taylor, N. Zane

    The Madison Dynamo experiment drives a turbulent flow of liquid sodium in a sphere in order to observe a MHD dynamo instability: An exponentially growing magnetic field at the expense of kinetic energy. Initial runs of the experiment observed intermittent bursts of the predicted magnetic mode, but no self-excited field was observed. It was found that turbulent fluctuations were producing large-scale magnetic fields that were a significant fraction of the magnitude of the fields induced by the mean flow. These turbulent-induced fields were solely detrimental, opposing the generation of the magnetic field produced by the mean flow. Baffles and vanes were added to the experiment to optimize the helical pitch of the mean flow and to remove the large-scale detrimental fluctuations. The observed drop in required motor power and a drop in specific measured magnetic response modes gives direct confirmation that these large detrimental eddies have been removed. A probe was developed to characterize the turbulence in the MDE after the baffles were installed and it was determined that the remaining turbulent EMF was mostly acting as an enhanced dissipation to the induced magnetic field. After these modifications, the induced magnetic field produced by the flowing sodium interacting with a seed magnetic field now closely matches laminar predictions. However, no self-excited field has been observed. A velocity inversion technique has been developed that compares internal and external field measurements with a predictive model and determines what the effective mean flow is in the experiment. Results from this velocity inversion give another metric on how optimized the flow profile is and also provide the most robust method of determining how close the experiment is to achieving a dynamo.

  7. Instability of flow of liquid film over a heated surface

    SciTech Connect

    Sha, W.T.; Soo, S.L.

    1994-08-01

    Fundamental concepts and basic equations of a flowing thin liquid film cooling a heated surfaced by its vaporization and the effect of dry patches were treated. Stable film flow prior to the appearance of dry patches on the heated surface is maintained by a balance of various forces due to surface tension, shear stress, heat and mass transfer, and gravity. Film splitting at a critical film thickness produces dry patches due to perturbation by waves on a perfect surface, and often by surface imperfection and uneven heating. This work is primarily motivated by the design of next-generation nuclear reactors, which employ many novel passive heat-removal systems via natural circulation. These systems are design to prevent damage to the reactor core and containment without action by the reactor operators during or after a design basis accident such as a loss of coolant accident (LOCA) or a main steam-line break (MSLB) accident.

  8. Characterization of annular two-phase gas-liquid flows in microgravity

    NASA Technical Reports Server (NTRS)

    Bousman, W. Scott; Mcquillen, John B.

    1994-01-01

    A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

  9. Liquid-phase microextraction combined with graphite furnace atomic absorption spectrometry: A review.

    PubMed

    de la Calle, Inmaculada; Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2016-09-14

    An overview of the combination of liquid-phase microextraction (LPME) techniques with graphite furnace atomic absorption spectrometry (GFAAS) is reported herein. The high sensitivity of GFAAS is significantly enhanced by its association with a variety of miniaturized solvent extraction approaches. LPME-GFAAS thus represents a powerful combination for determination of metals, metalloids and organometallic compounds at (ultra)trace level. Different LPME modes used with GFAAS are briefly described, and the experimental parameters that show an impact in those microextraction processes are discussed. Special attention is paid to those parameters affecting GFAAS analysis. Main issues found when coupling LPME and GFAAS, as well as those strategies reported in the literature to solve them, are summarized. Relevant applications published on the topic so far are included. PMID:27566338

  10. Pinch off and reconnection in liquid/liquid flows: joint experimental and numerical studies

    SciTech Connect

    Ellen K. Longmire; John S. Lowengrub

    2005-09-26

    Liquid/liquid systems appear in applications involving transport, mixing, and separation of petroleum, chemical, and waste products. Breakup and coalescence transitions often determine flow regimes as well as reaction and separation rates. Because they occur over very small time and length scales compared with the larger scales that dominate the flow, they are difficult to quantify experimentally and simulate numerically. Thus far, no accurate models exist for engineers to predict these flows. Experiments and computations were performed so that accurate engineering models can be developed. Jet pinch off and drop coalescence were examined in mixtures of water/glycerin and silicone oil. Index matching, laser sheet illumination, and the PIV method were applied to obtain visualization and velocity field sequences through transitions. The computations used a novel, physically-based method that captures interface breakup and coalescence automatically without resorting to ad-hoc cut-and-connect methods. To achieve enhanced accuracy near transitions, new adaptive time and space meshes were developed. The computations were validated through direct comparison with the experiments. The detailed results should lead to improved understanding of transition behavior. This understanding is needed to develop engineering models of multiphase flows. Such predictive models will lead to extensive cost savings in device and process design.

  11. Determination of lead and cadmium using an ionic liquid and dispersive liquid-liquid microextraction followed by electrothermal atomic absorption spectrometry.

    PubMed

    López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

    2013-06-15

    A procedure for the determination of ultratrace levels of lead and cadmium using dispersive liquid-liquid microextraction followed by electrothermal atomic absorption spectrometry (ETAAS) has been developed. The ionic liquid, 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C8MIm][NTf2]), is formed in situ and used to extract the lead and cadmium complexes with ammonium pyrrolidinedithiocarbamate. The very fine droplets of ([C8MIm][NTf2]) allow effective dispersion without the need for organic solvents. After centrifugation, the concentrations of lead and cadmium in the sedimented phase can be determined by ETAAS. Using a 10 mL aqueous sample, the enrichment factor of the procedure was 280 and detection limits of 0.2 and 3 ng L(-1) were obtained for cadmium and lead, respectively. The relative standard deviations for 10 replicates at the 10 ng L(-1) cadmium and 0.2 μg L(-1) lead levels were 6.5 and 7.3%, respectively. The method was successfully applied to the analysis of waters as well as to lixiviates obtained from toys made of plastic materials. PMID:23618174

  12. Measurement of transient gas flow parameters by diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Bolshov, M. A.; Kuritsyn, Yu A.; Liger, V. V.; Mironenko, V. R.; Nadezhdinskii, A. I.; Ponurovskii, Ya Ya; Leonov, S. B.; Yarantsev, D. A.

    2015-04-01

    An absorption spectrometer based on diode lasers is developed for measuring two-dimension maps of temperature and water vapour concentration distributions in the combustion zones of two mixing supersonic flows of fuel and oxidiser in the single run regime. The method of measuring parameters of hot combustion zones is based on detection of transient spectra of water vapour absorption. The design of the spectrometer considerably reduces the influence of water vapour absorption along the path of a sensing laser beam outside the burning chamber. The optical scheme is developed, capable of matching measurement results in different runs of mixture burning. A new algorithm is suggested for obtaining information about the mixture temperature by constructing the correlation functions of the experimental spectrum with those simulated from databases. A two-dimensional map of temperature distribution in a test chamber is obtained for the first time under the conditions of plasma-induced combusion of the ethylene - air mixture.

  13. Antibiotic toxicity and absorption in zebrafish using liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Fan; Qin, Wei; Zhang, Jing-Pu; Hu, Chang-Qin

    2015-01-01

    Evaluation of drug toxicity is necessary for drug safety, but in vivo drug absorption is varied; therefore, a rapid, sensitive and reliable method for measuring drugs is needed. Zebrafish are acceptable drug toxicity screening models; we used these animals with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in a multiple reaction monitoring mode to quantify drug uptake in zebrafish to better estimate drug toxicity. Analytes were recovered from zebrafish homogenate by collecting supernatant. Measurements were confirmed for drugs in the range of 10-1,000 ng/mL. Four antibiotics with different polarities were tested to explore any correlation of drug polarity, absorption, and toxicity. Zebrafish at 3 days post-fertilization (dpf) absorbed more drug than those at 6 h post-fertilization (hpf), and different developmental periods appeared to be differentially sensitive to the same compound. By observing abnormal embryos and LD50 values, zebrafish embryos at 6 hpf were considered to be suitable for evaluating embryotoxicity. Also, larvae at 3 dpf were adapted to measure acute drug toxicity in adult mammals. Thus, we can exploit zebrafish to study drug toxicity and can reliably quantify drug uptake with LC-MS/MS. This approach will be helpful for future studies of toxicology in zebrafish. PMID:25938774

  14. Nonlinear Saturable Absorption of Liquid-Exfoliated Molybdenum/Tungsten Ditelluride Nanosheets.

    PubMed

    Mao, Dong; Du, Bobo; Yang, Dexing; Zhang, Shengli; Wang, Yadong; Zhang, Wending; She, Xiaoyang; Cheng, Huachao; Zeng, Haibo; Zhao, Jianlin

    2016-03-01

    Molybdenum disulfide (MoS2 ) and tungsten disulfide (WS2 ), two representative transition metal dichalcogenide materials, have captured tremendous interest for their unique electronic, optical, and chemical properties. Compared with MoS2 and WS2 , molybdenum ditelluride (MoTe2 ) and tungsten ditelluride (WTe2 ) possess similar lattice structures while having smaller bandgaps (less than 1 eV), which is particularly interesting for applications in the near-infrared wavelength regime. Here, few-layer MoTe2 /WTe2 nanosheets are fabricated by a liquid exfoliation method using sodium deoxycholate bile salt as surfactant, and the nonlinear optical properties of the nanosheets are investigated. The results demonstrate that MoTe2 /WTe2 nanosheets exhibit nonlinear saturable absorption property at 1.55 μm. Soliton mode-locking operations are realized separately in erbium-doped fiber lasers utilizing two types of MoTe2 /WTe2 -based saturable absorbers, one of which is prepared by depositing the nanosheets on side polished fibers, while the other is fabricated by mixing the nanosheets with polyvinyl alcohol and then evaporating them on substrates. Numerous applications may benefit from the nonlinear saturable absorption features of MoTe2 /WTe2 nanosheets, such as visible/near-infrared pulsed laser, materials processing, optical sensors, and modulators. PMID:26800122

  15. Antibiotic Toxicity and Absorption in Zebrafish Using Liquid Chromatography-Tandem Mass Spectrometry

    PubMed Central

    Zhang, Fan; Qin, Wei; Zhang, Jing-Pu; Hu, Chang-Qin

    2015-01-01

    Evaluation of drug toxicity is necessary for drug safety, but in vivo drug absorption is varied; therefore, a rapid, sensitive and reliable method for measuring drugs is needed. Zebrafish are acceptable drug toxicity screening models; we used these animals with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in a multiple reaction monitoring mode to quantify drug uptake in zebrafish to better estimate drug toxicity. Analytes were recovered from zebrafish homogenate by collecting supernatant. Measurements were confirmed for drugs in the range of 10–1,000 ng/mL. Four antibiotics with different polarities were tested to explore any correlation of drug polarity, absorption, and toxicity. Zebrafish at 3 days post-fertilization (dpf) absorbed more drug than those at 6 h post-fertilization (hpf), and different developmental periods appeared to be differentially sensitive to the same compound. By observing abnormal embryos and LD50 values, zebrafish embryos at 6 hpf were considered to be suitable for evaluating embryotoxicity. Also, larvae at 3 dpf were adapted to measure acute drug toxicity in adult mammals. Thus, we can exploit zebrafish to study drug toxicity and can reliably quantify drug uptake with LC-MS/MS. This approach will be helpful for future studies of toxicology in zebrafish. PMID:25938774

  16. Marangoni instability of a liquid film flow with viscous dissipation.

    PubMed

    Celli, Michele; Barletta, Antonio; Alves, Leonardo S de B

    2015-02-01

    A linear stability analysis of a thin liquid film flowing over a plate is performed. The plate is considered as impermeable and adiabatic. The upper surface of the film is assumed to be a free boundary with a non-negligible surface tension, characterized by a Robin thermal boundary condition. The thermoconvective instability is generated by the interplay between the heating due to viscous dissipation and the temperature-dependent surface tension at the free boundary. A basic parallel flow, arbitrarily oriented, is assumed and the basic temperature profile is determined analytically. In order to investigate the linear stability of the system, the normal mode method is employed. A system of ordinary differential equations defining an eigenvalue problem is thus obtained. The case of longitudinal rolls, where the base flow velocity is parallel to the axis rolls, is solved both analytically and numerically. Other possible inclinations of the base flow are investigated by means of a numerical procedure based on combining the Runge-Kutta and the shooting methods. PMID:25768596

  17. Marangoni instability of a liquid film flow with viscous dissipation

    NASA Astrophysics Data System (ADS)

    Celli, Michele; Barletta, Antonio; Alves, Leonardo S. de B.

    2015-02-01

    A linear stability analysis of a thin liquid film flowing over a plate is performed. The plate is considered as impermeable and adiabatic. The upper surface of the film is assumed to be a free boundary with a non-negligible surface tension, characterized by a Robin thermal boundary condition. The thermoconvective instability is generated by the interplay between the heating due to viscous dissipation and the temperature-dependent surface tension at the free boundary. A basic parallel flow, arbitrarily oriented, is assumed and the basic temperature profile is determined analytically. In order to investigate the linear stability of the system, the normal mode method is employed. A system of ordinary differential equations defining an eigenvalue problem is thus obtained. The case of longitudinal rolls, where the base flow velocity is parallel to the axis rolls, is solved both analytically and numerically. Other possible inclinations of the base flow are investigated by means of a numerical procedure based on combining the Runge-Kutta and the shooting methods.

  18. Flowing Foam: T1 events and solid-liquid transitions.

    NASA Astrophysics Data System (ADS)

    Dennin, Michael

    2005-11-01

    Flowing aqueous foam is found in many applications ranging from oil recovery, to fire fighting, to spreading shaving cream. Aqueous foam consists of gas bubbles with liquid walls. One of the striking features of foam is that despite being composed entirely of fluids, its mechanical properties are either those of a solid (elastic response) or fluid (viscous flow), depending on the nature of the applied stress and strains. We study the transition between these two regimes using a model foam system: bubble rafts. Bubble rafts are a single layer of bubbles floating on the air-water surface. This allows us to track the motion of all the bubbles during flow. In this talk, we will present two main results. First, we will discuss the observation of the coexistence between a solid-like and fluid-like state during flow. Second, we will discuss the role played by nonlinear, topological rearrangements, known as T1 events, in determining the mechanical response of the system.

  19. Scattered light and accuracy of the cross-section measurements of weak absorptions: Gas and liquid phase UV absorption cross sections of CH3CFCl2

    NASA Technical Reports Server (NTRS)

    Fahr, A.; Braun, W.; Kurylo, M. J.

    1993-01-01

    Ultraviolet absorption cross sections of CH3CFCl2(HCFC-141b) were determined in the gas phase (190-260 nm) and liquid phase (230-260 mm) at 298 K. The liquid phase absorption cross sections were then converted into accurate gas phase values using a previously described procedure. It has been demonstrated that scattered light from the shorter-wavelength region (as little as several parts per thousand) can seriously compromise the absorption cross-section measurement, particularly at longer wavelengths where cross sections are low, and can be a source of discrepancies in the cross sections of weakly absorbing halocarbons reported in the literature. A modeling procedure was developed to assess the effect of scattered light on the measured absorption cross section in our experiments, thereby permitting appropriate corrections to be made on the experimental values. Modeled and experimental results were found to be in good agreement. Experimental results from this study were compared with other available determinations and provide accurate input for calculating the atmospheric lifetime of HCFC-141b.

  20. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  1. Large Flow-Birefringence of Nematogenic Bent-Core Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Bailey, Christopher; Fodor-Csorba, Katalin; Verduzco, Rafael; Gleeson, James; Sprunt, Samuel; Jakli, Antal

    2009-03-01

    We have found that bent-core liquid crystalline materials show exceptionally large flow birefringence in their isotropic liquid phase. The flow birefringence is over two orders of magnitude larger than usual for low molecular weight liquid crystals. Comparing the flow birefringence per unit viscosity, the observed values are an order of magnitude larger than low molecular weight and side-chain polymeric calamitic liquid crystals. This large flow birefringence is attributed to the nanostructure of these materials that contain temporary smectic clusters of a few smectic layers, which exist even in their isotropic phase. These smectic clusters appear to shear align resulting in the observed flow birefringence behavior.

  2. On-line sequential injection dispersive liquid-liquid microextraction system for flame atomic absorption spectrometric determination of copper and lead in water samples.

    PubMed

    Anthemidis, Aristidis N; Ioannou, Kallirroy-Ioanna G

    2009-06-30

    A simple, sensitive and powerful on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system was developed as an alternative approach for on-line metal preconcentration and separation, using extraction solvent at microlitre volume. The potentials of this novel schema, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace copper and lead determination in water samples. The stream of methanol (disperser solvent) containing 2.0% (v/v) xylene (extraction solvent) and 0.3% (m/v) ammonium diethyldithiophosphate (chelating agent) was merged on-line with the stream of sample (aqueous phase), resulting a cloudy mixture, which was consisted of fine droplets of the extraction solvent dispersed entirely into the aqueous phase. By this continuous process, metal chelating complexes were formed and extracted into the fine droplets of the extraction solvent. The hydrophobic droplets of organic phase were retained into a microcolumn packed with PTFE-turnings. A portion of 300 microL isobutylmethylketone was used for quantitative elution of the analytes, which transported directly to the nebulizer of FAAS. All the critical parameters of the system such as type of extraction solvent, flow-rate of disperser and sample, extraction time as well as the chemical parameters were studied. Under the optimum conditions the enhancement factor for copper and lead was 560 and 265, respectively. For copper, the detection limit and the precision (R.S.D.) were 0.04 microg L(-1) and 2.1% at 2.0 microg L(-1) Cu(II), respectively, while for lead were 0.54 microg L(-1) and 1.9% at 30.0 microg L(-1) Pb(II), respectively. The developed method was evaluated by analyzing certified reference material and applied successfully to the analysis of environmental water samples. PMID:19376348

  3. Gravity-driven liquid flow over a flexible beam

    NASA Astrophysics Data System (ADS)

    Kim, Hyoungsoo; Howell, Peter; Popova, Marinela; Stone, Howard

    2015-11-01

    We study theoretically and experimentally the time dependence of a liquid spreading along a flexible beam. The flow is modeled using lubrication theory and the substrate is modeled as an (Euler-Bernoulli) elastic beam. We classify the model problem into two cases depending on the maximum beam deflection angle ϕmax from the horizontal, i.e. a small deflection (ϕmax < 30°) and large deflection (30° < ϕmax < 90°). For a small deflection case, we obtain asymptotic solutions for the liquid propagation speed for the early time and terminal time periods, which for the front position σ(t) show power-law behaviors σ(t) ~ t 4 / 5 and σ(t) ~ t4, respectively. The theoretical model also predicts the deflection angle of the beam at the propagating liquid front. We validate the results with experiments, which show good agreement with theory. Furthermore, for large beam deflections, we obtain experimental results demonstrating power-law behaviors, σ(t) ~ t and ϕ(t) ~ t2 for the early time period.

  4. Two-phase, gas-liquid flows in static mixers

    SciTech Connect

    Shah, N.F.; Kale, D.D. )

    1992-02-01

    This paper reports that static mixers are used for many gas-liquid two-phase operations. some of the typical applications are processing of natural gas to remove hydrogen sulfide or carbon dioxide, waste water treatment, dissolution of gases, hydrogenation, chlorination, and so on. They have experimentally studied the pressure drop for oxygen-water system in a bubble column packed with Sulzer-Koch-type mixing elements. They observed that the ratio of pressure drop through the packed bubble column to that through the unpacked one was slightly greater than one. The suitability of static mixers to mix fluids of very widely different viscosities has been demonstrated. Two-phase operations in polymer industry involve very viscous fluids. Due to the high viscosity of these fluids, the flow will be predominantly in laminar region for both fluids. There are no data on gas-liquid two-phase systems incorporating viscous Newtonian and non-Newtonian fluids where flows are predominantly in laminar region.

  5. Stabilising falling liquid film flows using feedback control

    NASA Astrophysics Data System (ADS)

    Thompson, Alice B.; Gomes, Susana N.; Pavliotis, Grigorios A.; Papageorgiou, Demetrios T.

    2016-01-01

    Falling liquid films become unstable due to inertial effects when the fluid layer is sufficiently thick or the slope sufficiently steep. This free surface flow of a single fluid layer has industrial applications including coating and heat transfer, which benefit from smooth and wavy interfaces, respectively. Here, we discuss how the dynamics of the system are altered by feedback controls based on observations of the interface height, and supplied to the system via the perpendicular injection and suction of fluid through the wall. In this study, we model the system using both Benney and weighted-residual models that account for the fluid injection through the wall. We find that feedback using injection and suction is a remarkably effective control mechanism: the controls can be used to drive the system towards arbitrary steady states and travelling waves, and the qualitative effects are independent of the details of the flow modelling. Furthermore, we show that the system can still be successfully controlled when the feedback is applied via a set of localised actuators and only a small number of system observations are available, and that this is possible using both static (where the controls are based on only the most recent set of observations) and dynamic (where the controls are based on an approximation of the system which evolves over time) control schemes. This study thus provides a solid theoretical foundation for future experimental realisations of the active feedback control of falling liquid films.

  6. Soft and broadband infrared metamaterial absorber based on gold nanorod/liquid crystal hybrid with tunable total absorption

    NASA Astrophysics Data System (ADS)

    Su, Zhaoxian; Yin, Jianbo; Zhao, Xiaopeng

    2015-11-01

    We design a soft infrared metamaterial absorber based on gold nanorods dispersed in liquid crystal (LC) placed on a gold film and theoretically investigate its total absorption character. Because the nanorods align with the LC molecule, the gold nanorods/LC hybrid exhibits different permittivity as a function of tilt angle of LC. At a certain tilt angle, the absorber shows an omnidirectional total absorption effect. By changing the tilt angle of LC by an external electric field, the total absorption character can be adjusted. The total absorption character also depends on the concentration, geometric dimension of nanorods, and defect of nanorod arrangement in LC. When the LC contains different size of gold nanorods, a broadband absorption can be easily realized. The characteristics including flexibility, omnidirectional, broadband and tunablility make the infrared metamaterial absorber possess potential use in smart metamaterial devices.

  7. Soft and broadband infrared metamaterial absorber based on gold nanorod/liquid crystal hybrid with tunable total absorption

    PubMed Central

    Su, Zhaoxian; Yin, Jianbo; Zhao, Xiaopeng

    2015-01-01

    We design a soft infrared metamaterial absorber based on gold nanorods dispersed in liquid crystal (LC) placed on a gold film and theoretically investigate its total absorption character. Because the nanorods align with the LC molecule, the gold nanorods/LC hybrid exhibits different permittivity as a function of tilt angle of LC. At a certain tilt angle, the absorber shows an omnidirectional total absorption effect. By changing the tilt angle of LC by an external electric field, the total absorption character can be adjusted. The total absorption character also depends on the concentration, geometric dimension of nanorods, and defect of nanorod arrangement in LC. When the LC contains different size of gold nanorods, a broadband absorption can be easily realized. The characteristics including flexibility, omnidirectional, broadband and tunablility make the infrared metamaterial absorber possess potential use in smart metamaterial devices. PMID:26576660

  8. Optofluidic single-cell absorption flow analyzer for point-of-care diagnosis of malaria.

    PubMed

    Banoth, Earu; Kasula, Vamshi Krishna; Jagannadh, Veerendra Kalyan; Gorthi, Sai Siva

    2016-06-01

    In this work, an optofluidic flow analyzer, which can be used to perform malaria diagnosis at the point-of-care is demonstrated. The presented technique is based on quantitative optical absorption measurements carried out on a single cell level for a given population of Human Red Blood Cells (RBCs). By measuring the optical absorption of each RBC, the decrease in the Hemoglobin (Hb) concentration in the cytoplasm of the cell due to the invasion of malarial parasite is detected. Cells are assessed on a single cell basis, as they pass through a microfluidic channel. The proposed technique has been implemented with inexpensive off-the-shelf components like laser diode, photo-detector and a micro-controller. The ability of the optofluidic flow analyzer to asses about 308,049 cells within 3 minutes has been demonstrated. The presented technique is capable of detecting very low parasitemia levels with high sensitivity. PMID:26192714

  9. High-throughput liquid-absorption air-sampling apparatus and methods

    SciTech Connect

    2000-07-11

    A portable high-throughput liquid-absorption air sampler [PHTLAAS] has an asymmetric air inlet through which air is drawn upward by a small and light-weight centrifugal fan driven by a direct current motor that can be powered by a battery. The air inlet is so configured as to impart both rotational and downward components of motion to the sampled air near said inlet. The PHTLAAS comprises a glass tube of relatively small size through which air passes at a high rate in a swirling, highly turbulent motion, which facilitates rapid transfer of vapors and particulates to a liquid film covering the inner walls of the tube. The pressure drop through the glass tube is < 10 cm of water, usually < 5 cm of water. The sampler's collection efficiency is usually > 20% for vapors or airborne particulates in the 2--3 microns range and > 50% for particles larger than 4 microns. In conjunction with various analyzers, the PHTLAAS can serve to monitor a variety of hazardous or illicit airborne substances, such as lead-containing particulates, tritiated water vapor, biological aerosols, or traces of concealed drugs or explosives.

  10. High-throughput liquid-absorption air-sampling apparatus and methods

    DOEpatents

    Zaromb, Solomon

    2000-01-01

    A portable high-throughput liquid-absorption air sampler [PHTLAAS] has an asymmetric air inlet through which air is drawn upward by a small and light-weight centrifugal fan driven by a direct current motor that can be powered by a battery. The air inlet is so configured as to impart both rotational and downward components of motion to the sampled air near said inlet. The PHTLAAS comprises a glass tube of relatively small size through which air passes at a high rate in a swirling, highly turbulent motion, which facilitates rapid transfer of vapors and particulates to a liquid film covering the inner walls of the tube. The pressure drop through the glass tube is <10 cm of water, usually <5 cm of water. The sampler's collection efficiency is usually >20% for vapors or airborne particulates in the 2-3.mu. range and >50% for particles larger than 4.mu.. In conjunction with various analyzers, the PHTLAAS can serve to monitor a variety of hazardous or illicit airborne substances, such as lead-containing particulates, tritiated water vapor, biological aerosols, or traces of concealed drugs or explosives.

  11. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry for a sensitive determination of cadmium in water samples

    NASA Astrophysics Data System (ADS)

    Li, Shengqing; Cai, Shun; Hu, Wei; Chen, Hao; Liu, Hanlan

    2009-07-01

    A new method was developed for the determination of cadmium in water samples using ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-based USA-DLLME) followed by electrothermal atomic absorption spectrometry (ETAAS). The IL-based USA-DLLME procedure is free of volatile organic solvents, and there is no need for a dispersive solvent, in contrast to conventional DLLME. The ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6), was quickly disrupted by an ultrasonic probe for 1 min and dispersed in water samples like a cloud. At this stage, a hydrophobic cadmium-DDTC complex was formed and extracted into the fine droplets of HMIMPF 6. After centrifugation, the concentration of the enriched cadmium in the sedimented phase was determined by ETAAS. Some effective parameters of the complex formation and microextraction, such as the concentration of the chelating agent, the pH, the volume of the extraction solvent, the extraction time, and the salt effect, have been optimized. Under optimal conditions, a high extraction efficiency and selectivity were reached for the extraction of 1.0 ng of cadmium in 10.0 mL of water solution employing 73 µL of HMIMPF 6 as the extraction solvent. The enrichment factor of the method is 67. The detection limit was 7.4 ng L - 1 , and the characteristic mass ( m0, 0.0044 absorbance) of the proposed method was 0.02 pg for cadmium (Cd). The relative standard deviation (RSD) for 11 replicates of 50 ng L - 1 Cd was 3.3%. The method was applied to the analysis of tap, well, river, and lake water samples and the Environmental Water Reference Material GSBZ 50009-88 (200921). The recoveries of spiked samples were in the range of 87.2-106%.

  12. Optical absorption properties of electron bubbles and experiments on monitoring individual electron bubbles in liquid helium

    NASA Astrophysics Data System (ADS)

    Guo, Wei

    When a free electron is injected into liquid helium, it forms a microscopic bubble essentially free of helium atoms, which is referred to as an electron bubble. It represents a fine example of a quantum-mechanical particle confined in a potential well. In this dissertation, we describe our studies on bubble properties, especially the optical absorption properties of ground state electron bubbles and experiments on imaging individual electron bubbles in liquid helium. We studied the effect of zero-point and thermal fluctuations on the shape of ground state electron bubbles in liquid helium. The results are used to determine the line shape for the 1S to 1P optical transition. The calculated line shape is in very good agreement with the experimental measurements of Grimes and Adams. For 1S to 2P transition, the obtained transition line width agrees well with the measured data of Zipfel over a range of pressure up to 15 bars. Fluctuations in the bubble shape also make other "unallowed" transitions possible. The transition cross-sections from the 1S state to the 1D and 2D states are calculated with magnitude approximately two orders smaller than that of the 1S to 1P and 2P transitions. In our electron bubble imaging experiments, a planar ultrasonic transducer was used to generate strong sound wave pulse in liquid helium. The sound pulse passed through the liquid so as to produce a transient negative pressure over a large volume (˜ 1 cm3). An electron bubble that was passed by the sound pulse exploded for a fraction of a microsecond and grew to have a radius of around 10 microns. While the bubble had this large size it was illuminated with a flash lamp and its position was recorded. In this way, we can determine its position. Through the application of a series of sound pulses, we can then take images along the track of individual electrons. The motion of individual electron bubbles has been successfully monitored. Interesting bubble tracks that may relate to electrons

  13. Supersonic Mass Flux Measurements via Tunable Diode Laser Absorption and Non-Uniform Flow Modeling

    NASA Technical Reports Server (NTRS)

    Chang, Leyen S.; Strand, Christopher L.; Jeffries, Jay B.; Hanson, Ronald K.; Diskin, Glenn S.; Gaffney, Richard L.; Capriotti, Diego P.

    2011-01-01

    Measurements of mass flux are obtained in a vitiated supersonic ground test facility using a sensor based on line-of-sight (LOS) diode laser absorption of water vapor. Mass flux is determined from the product of measured velocity and density. The relative Doppler shift of an absorption transition for beams directed upstream and downstream in the flow is used to measure velocity. Temperature is determined from the ratio of absorption signals of two transitions (lambda(sub 1)=1349 nm and lambda(sub 2)=1341.5 nm) and is coupled with a facility pressure measurement to obtain density. The sensor exploits wavelength-modulation spectroscopy with second-harmonic detection (WMS-2f) for large signal-to-noise ratios and normalization with the 1f signal for rejection of non-absorption related transmission fluctuations. The sensor line-of-sight is translated both vertically and horizontally across the test section for spatially-resolved measurements. Time-resolved measurements of mass flux are used to assess the stability of flow conditions produced by the facility. Measurements of mass flux are within 1.5% of the value obtained using a facility predictive code. The distortion of the WMS lineshape caused by boundary layers along the laser line-of-sight is examined and the subsequent effect on the measured velocity is discussed. A method for correcting measured velocities for flow non-uniformities is introduced and application of this correction brings measured velocities within 4 m/s of the predicted value in a 1630 m/s flow.

  14. Numerical simulations of high Knudsen number gas flows and microchannel electrokinetic liquid flows

    NASA Astrophysics Data System (ADS)

    Yan, Fang

    Low pressure and microchannel gas flows are characterized by high Knudsen numbers. Liquid flows in microchannels are characterized by non-conventional driving potentials like electrokinetic forces. The main thrust of the dissertation is to investigate these two different kinds of flows in gases and liquids respectively. High Knudsen number (Kn) gas flows were characterized by 'rarified' or 'microscale' behavior. Because of significant non-continuum effect, traditional CFD techniques are often inaccurate for analyzing high Kn number gas flows. The direct simulation Monte Carlo (DSMC) method offers an alternative to traditional CFD which retains its validity in slip and transition flow regimes. To validate the DSMC code, comparisons of simulation results with theoretical analysis and experimental data are made. The DSMC method was first applied to compute low pressure, high Kn flow fields in partially heated two dimensional channels. The effects of varying pressure, inlet flow and gas transport properties (Kn, Reynolds number, Re and the Prandtl number, Pr respectively) on the wall heat transfer (Nusselt number, Nu) were examined. The DSMC method was employed to explore mixing gas flows in two dimensional microchannels. Mixing of two gas streams (H2 and O2) was considered within a microchannel. The effect of the inlet-outlet pressure difference, the pressure ratio of the incoming streams and the accommodation coefficient of the solid wall on mixing length were all examined. Parallelization of a three-dimensional DSMC code was implemented using OpenMP procedure on a shared memory multi-processor computer. The parallel code was used to simulate 3D high Kn number Couette flow and the flow characteristics are found to be very different from their continuum counterparts. A mathematical model describing electrokinetically driven mass transport phenomena in microfabricated chip devices will also be presented. The model accounts for the principal physical phenomena affecting

  15. Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics

    NASA Astrophysics Data System (ADS)

    Hart, Roger C.; Herring, G. C.; Balla, R. Jeffrey

    2007-06-01

    Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  16. Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

    2007-01-01

    Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

  17. Ionic Liquids: Breakthrough Absorption Technology for Post-Combustion CO{sub 2} Capture

    SciTech Connect

    Maginn, Edward

    2012-09-30

    This is the final report for DE-FC26-07NT43091 Ionic Liquids: Breakthrough Absorption Technology for Post-Combustion CO{sub 2} Capture. A detailed summary is provided of the ionic liquid (IL) discovery process, synthesis and testing results, process / systems modeling, lab-scale operational testing, corrosion testing and commercialization possibilities. The work resulted in the discovery of a new class of ionic liquids (ILs) that efficiently react with CO{sub 2} in a 1:1 stoichiometry with no water present and no increase in viscosity. The enthalpy of reaction was tuned to optimize process economics. The IL was found to have excellent corrosion behavior with and without CO{sub 2} present. In lab-scale tests, the IL was able to effectively remove CO{sub 2} from a simulated flue gas stream, although mass transfer was slower than with aqueous monoethanolamine (MEA) due to higher viscosities. The non-volatile nature of the solvent and its high thermal stability, however, make it an intriguing option. An independent systems analysis indicates that the economics of using the best IL discovered to date (NDIL0157), are at least comparable to and potentially slightly better than - the Fluor Econamine FG PlusTM process (DOE Case 12). Further work should be directed at improving mass transfer / lowering viscosity and developing commercial synthesis routes to make these ILs at scale in an inexpensive manner. Demonstration of the process at larger scales is also warranted, as is the exploration of other process configurations that leverage the anhydrous nature of the solvent and its extremely low volatility.

  18. Anomalous effect of flow rate on the electrochemical behavior at a liquid|liquid interface under microfluidic conditions.

    PubMed

    Kaluza, Dawid; Adamiak, Wojciech; Kalwarczyk, Tomasz; Sozanski, Krzysztof; Opallo, Marcin; Jönsson-Niedziolka, Martin

    2013-12-23

    We have investigated the oxidation of ferrocene at a flowing organic solvent|aqueous electrolyte|solid electrode junction in a microfluidic setup using cyclic voltammetry and fluorescent laser scanning confocal microscopy. At low flow rates the oxidation current decreases with increasing flow, contrary to the Levich equation, but at higher flow rates the current increases linearly with the cube root of the flow rate. This behavior is explained using a simple model postulating a smallest effective width of the three-phase junction, which after fitting to the data comes to be ca. 20 μm. The fluorescence microscopy reveals mixing of the two phases close to the PDMS cover, but the liquid|liquid junction is stable close to the glass support. This study shows the importance of the solid|liquid|liquid junctions for the behavior of multiphase systems under microfluidic conditions. PMID:24328179

  19. A new coupling of ionic liquid based-single drop microextraction with tungsten coil electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Wen, Xiaodong; Deng, Qingwen; Wang, Jiwei; Yang, Shengchun; Zhao, Xia

    2013-03-01

    In this work, an improved method of ionic liquid based-single drop microextraction (IL-SDME) preconcentration was firstly coupled with tungsten coil electrothermal atomic absorption spectrometry (W-coil ET-AAS) detection. The new coupling was developed and applied for the determination of ultra-trace cadmium. Experimental parameters influencing the performance of IL-SDME as well as instrumental conditions were studied systematically, including IL-drop volume, chelating agent concentration, pH, stirring rate and time, heating program of W-coil ET-AAS, flow rate of carrier gas. Under the optimal conditions, the limit of detection (LOD) for cadmium was 0.015 μg L-1 (sampling amount on W-coil was 10 μL). The sensitivity enhancement factor was 42, while the improvement factor of LOD was 33. The established method was applied to determine cadmium in standard reference materials of rice and real water samples successfully. The developed IL-SDME-W-coil ET-AAS coupling represents a simple, green and highly sensitive method for cadmium determination.

  20. A versatile liquid-core/liquid-twin-cladding waveguide micro flow cell fabricated by rapid prototyping

    NASA Astrophysics Data System (ADS)

    Rosenauer, M.; Vellekoop, M. J.

    2009-10-01

    In this paper we present the design and operation of a micro flow cell comprising a liquid-core/liquid-twin-cladding waveguide for on-chip fluorescence spectroscopy based on evanescent field illumination. The application of an inner (sample) and outer cladding stream minimizes the sample volume for optical measurements and ensures the analyte position in the evanescent field for excitation at the core/cladding interface. The fiber-chip-coupled laser light is guided by the fluidic waveguide providing a uniform excitation along the analysis channel. Fluorescence intensity measurements of different sample solutions were conducted to illustrate the operational quality. The fluidics device is fabricated by laser microstereolithography in 1.5 h.

  1. Light-Driven Transport of a Liquid Marble with and against Surface Flows.

    PubMed

    Kavokine, Nikita; Anyfantakis, Manos; Morel, Mathieu; Rudiuk, Sergii; Bickel, Thomas; Baigl, Damien

    2016-09-01

    Liquid marbles, that is, liquid drops coated by a hydrophobic powder, do not wet any solid or liquid substrate, making their transport and manipulation both highly desirable and challenging. Herein, we describe the light-driven transport of floating liquid marbles and emphasize a surprising motion behavior. Liquid marbles are deposited on a water solution containing photosensitive surfactants. Irradiation of the solution generates photoreversible Marangoni flows that transport the liquid marbles toward UV light and away from blue light when the thickness of the liquid substrate is large enough (Marangoni regime). Below a critical thickness, the liquid marbles move in the opposite direction to that of the surface flow at a speed increasing with decreasing liquid thickness (anti-Marangoni). We demonstrate that the anti-Marangoni motion is driven by the free surface deformation, which propels the non-wetting marble against the surface flow. We call this behavior "slide effect". PMID:27381297

  2. Diode laser absorption sensors for gas-dynamic and combustion flows

    NASA Technical Reports Server (NTRS)

    Allen, M. G.

    1998-01-01

    Recent advances in room-temperature, near-IR and visible diode laser sources for tele-communication, high-speed computer networks, and optical data storage applications are enabling a new generation of gas-dynamic and combustion-flow sensors based on laser absorption spectroscopy. In addition to conventional species concentration and density measurements, spectroscopic techniques for temperature, velocity, pressure and mass flux have been demonstrated in laboratory, industrial and technical flows. Combined with fibreoptic distribution networks and ultrasensitive detection strategies, compact and portable sensors are now appearing for a variety of applications. In many cases, the superior spectroscopic quality of the new laser sources compared with earlier cryogenic, mid-IR devices is allowing increased sensitivity of trace species measurements, high-precision spectroscopy of major gas constituents, and stable, autonomous measurement systems. The purpose of this article is to review recent progress in this field and suggest likely directions for future research and development. The various laser-source technologies are briefly reviewed as they relate to sensor applications. Basic theory for laser absorption measurements of gas-dynamic properties is reviewed and special detection strategies for the weak near-IR and visible absorption spectra are described. Typical sensor configurations are described and compared for various application scenarios, ranging from laboratory research to automated field and airborne packages. Recent applications of gas-dynamic sensors for air flows and fluxes of trace atmospheric species are presented. Applications of gas-dynamic and combustion sensors to research and development of high-speed flows aeropropulsion engines, and combustion emissions monitoring are presented in detail, along with emerging flow control systems based on these new sensors. Finally, technology in nonlinear frequency conversion, UV laser materials, room

  3. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera.

    PubMed

    Wan, Yuhang; Carlson, John A; Kesler, Benjamin A; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A; Lim, Sung Jun; Smith, Andrew M; Dallesasse, John M; Cunningham, Brian T

    2016-01-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid's absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070

  4. Velocity measurement of two-phase liquid-gas flow in a horizontal pipeline using gamma densitometry

    NASA Astrophysics Data System (ADS)

    Hanus, R.; Zych, M.; Petryka, L.

    2014-08-01

    This paper presents application of gamma-ray absorption method to liquid-gas flow investigation in a pipeline. In the described measurement two sealed 241Am radioactive sources and probes with NaI(Tl) scintillation crystals have been used. For the analysis of digital signals provided by detectors, a traditional cross-correlation function (CCF), and modified correlation methods based on the quotient of CCF and average magnitude difference function (AMDF), as well as the quotient of CCF, and average square difference function (ASDF) have been proposed. Exemplary results of the mean velocity determination of the gaseous phase transported by a liquid in the water-air mixture flow were demonstrated and the evaluation of its uncertainty have been presented.

  5. In situ metathesis ionic liquid formation dispersive liquid-liquid microextraction for copper determination in water samples by electrothermal atomic absorption spectrometry.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka

    2013-10-15

    In situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with electrothermal atomic absorption spectrometry (ET AAS) for determination of copper in water samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination by AAS. Some essential parameters of the microextraction and detection techniques such as the pH of sample solution, volume of components for in situ synthesis, matrix interferences and main parameters of graphite furnace atomizer have been studied. Under optimal conditions, high extraction efficiency for copper was achieved for the extraction of 0.7 µg L(-1) in 10.0 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) as the extraction solvent. The detection limit was found as 0.004 µg L(-1) with an enrichment factor of 200. The relative standard deviation (RSD) for seven replicate measurements of 0.7 µg L(-1) in sample solution was 4%. The accuracy of the proposed method was evaluated by analysis of the Certified Reference Materials: NIST SRM 2709 (San Joaquin Soil), NBS SRM 2704 (Buffalo River Sediment), NRCC DOLT-2 (Dogfish Liver) and NIST SRM 1643e (Trace Element in Water). The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the tap, lake and mineral water samples. PMID:24054576

  6. Rocket engine coaxial injector liquid/gas interface flow phenomena

    SciTech Connect

    Mayer, W.; Kruelle, G.

    1995-05-01

    Coaxial injectors are used for the injection and mixing of propellants H2/O2 in cryogenic rocket engines. The aim of the theoretical and experimental investigations presented here is to elucidate some of the physical processes in coaxial injector flow with respect to their significance for atomization and mixing. Experiments with the simulation fluids H2O and air were performed under ambient conditions and at elevated counter pressures up to 20 bar. This article reports on phenomenological studies of spray generation under a broad variation of parameters using nanolight photography and high-speed cinematography (up to 3 x 10(exp 4) frames/s). Detailed theoretical and experimental studies of the surface evolution of turbulent jets were performed. Proof was obtained of the impact of internal fluid jet motions on surface deformation. The m = 1 nonaxisymmetric instability of the liquid jet seems to be superimposed onto the small-scale atomization process. A model is presented that calculates droplet atomization quantities as frequency, droplet diameter, and liquid core shape. The overall procedure for implementing this model as a global spray model is also described and an example calculation is presented. 15 refs.

  7. Direct fired absorption machine flue gas recuperator

    DOEpatents

    Reimann, Robert C.; Root, Richard A.

    1985-01-01

    A recuperator which recovers heat from a gas, generally the combustion gas of a direct-fired generator of an absorption machine. The recuperator includes a housing with liquid flowing therethrough, the liquid being in direct contact with the combustion gas for increasing the effectiveness of the heat transfer between the gas and the liquid.

  8. Measurements of liquid-phase turbulence in gas-liquid two-phase flows using particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Zhou, Xinquan; Doup, Benjamin; Sun, Xiaodong

    2013-12-01

    Liquid-phase turbulence measurements were performed in an air-water two-phase flow loop with a circular test section of 50 mm inner diameter using a particle image velocimetry (PIV) system. An optical phase separation method--planar laser-induced fluorescence (PLIF) technique—which uses fluorescent particles and an optical filtration technique, was employed to separate the signals of the fluorescent seeding particles from those due to bubbles and other noises. An image pre-processing scheme was applied to the raw PIV images to remove the noise residuals that are not removed by the PLIF technique. In addition, four-sensor conductivity probes were adopted to measure the radial distribution of the void fraction. Two benchmark tests were performed: the first was a comparison of the PIV measurement results with those of similar flow conditions using thermal anemometry from previous studies; the second quantitatively compared the superficial liquid velocities calculated from the local liquid velocity and void fraction measurements with the global liquid flow rate measurements. The differences of the superficial liquid velocity obtained from the two measurements were bounded within ±7% for single-phase flows and two-phase bubbly flows with the area-average void fraction up to 18%. Furthermore, a preliminary uncertainty analysis was conducted to investigate the accuracy of the two-phase PIV measurements. The systematic uncertainties due to the circular pipe curvature effects, bubble surface reflection effects and other potential uncertainty sources of the PIV measurements were discussed. The purpose of this work is to facilitate the development of a measurement technique (PIV-PLIF) combined with image pre-processing for the liquid-phase turbulence in gas-liquid two-phase flows of relatively high void fractions. The high-resolution data set can be used to more thoroughly understand two-phase flow behavior, develop liquid-phase turbulence models, and assess high

  9. Molecular simulation and experimental study of CO2 absorption in ionic liquid reverse micelle.

    PubMed

    Shi, Wei; Hong, Lei; Damodaran, Krishnan; Nulwala, Hunaid B; Luebke, David R

    2014-12-01

    The structure and dynamics for CO2 absorption in ionic liquid reverse micelle (ILRM) were studied using molecular simulations. The ILRM consisted of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) ionic liquid (IL) as the micelle core, the benzylhexadecyldimethylammonium ([BHD](+)) chloride ([Cl](-)) was the cationic surfactant, and benzene was used as the continuous solvent phase in this study. The diffusivity values of this ILRM system were also experimentally determined. Simulations indicate that there is ion exchange between the IL anion ([BF4](-)) and the surfactant anion ([Cl](-)). It was also found that the [bmim][BF4] IL exhibits small local density at the interface region between the IL core and the [BHD](+) surfactant cation layer, which leads to a smaller density for the [bmim][BF4] IL inside the reverse micelle (RM) compared with the neat IL. These simulation findings are consistent with experimental results. Both our simulations and experimental results show that [bmim][BF4] inside the RM diffuses 5-26 times faster than the neat IL, which is partly due to the fast particle diffusion for the ILRM nanodroplet (IL and surfactant) as a whole in benzene solvent compared with neat [bmim][BF4] diffusion. Additionally, it was found that [bmim][BF4] IL solved in benzene diffuses 2 orders of magnitude faster than the neat IL. Lastly, simulations show that CO2 molecules are absorbed in four different regions of the ILRM system, that is, (I) in the IL inner core, (II) in the [BHD](+) surfactant cation layer, (III) at the interface between the [BHD](+) surfactant cation layer and benzene solvent, and (IV) in the benzene solvent. The CO2 solubility was found to decrease in the order II > III ∼ IV > I, while the CO2 diffusivity and permeability decrease in the following order: IV > III > II > I. PMID:25382316

  10. A Study of Liquid Metal Film Flow, Under Fusion Relevant Magnetic Fields

    SciTech Connect

    Narula, M.; Ying, A.; Abdou, M.A.

    2005-04-15

    The use of flowing liquid metal streams or 'liquid walls' as a plasma contact surface is a very attractive option and has received considerable attention over the past several years both in the plasma physics and fusion engineering programs. A key issue for the feasibility of flowing liquid metal plasma facing component (PFC) systems, lies in their magnetohydrodynamic (MHD) behavior. The spatially varying magnetic field environment, typical of a fusion device can lead to serious flow disrupting MHD forces that hinder the development of a smooth and controllable flow needed for PFC applications. The present study builds up on the ongoing research effort at UCLA, directed towards providing qualitative and quantitative data on liquid metal free surface flow behavior under fusion relevant magnetic fields, to aid in better understanding of flowing liquid metal PFC systems.

  11. Material Flows in an Active Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Decamp, Stephen; Redner, Gabriel; Baskaran, Aparna; Hagan, Michael; Dogic, Zvonimir

    Active matter systems are composed of energy consuming constituent components which drive far-from-equilibrium dynamics. As such, active materials exhibit energetic states which would be unfavorable in passive, equilibrium materials. We study one such material; an active nematic liquid crystal which exists in a dynamical steady state where +/-1/2 defects are continuously generated and annihilated at a constant rate. The active nematic is composed of micron-sized microtubule filaments which are highly concentrated into a quasi-2D film that resides on an oil-water interface. Kinesin motor proteins drive inter-filament sliding which results in net extensile motion of the microtubule film. Notably, we find a mesophase in which motile +1/2 defects, acquire system-spanning orientational order. Currently, we are tracking material flows generated by the active stresses in the system to measure length scales at which energy is dissipated, and to measure the relation between internally generated flows and bend in the nematic field.

  12. Feedback control of flow alignment in sheared liquid crystals.

    PubMed

    Strehober, David A; Schöll, Eckehard; Klapp, Sabine H L

    2013-12-01

    Based on a continuum theory, we investigate the manipulation of the nonequilibrium behavior of a sheared liquid crystal via closed-loop feedback control. Our goal is to stabilize a specific dynamical state, that is, the stationary "flow alignment," under conditions where the uncontrolled system displays oscillatory director dynamics with in-plane symmetry. To this end we employ time-delayed feedback control (TDFC), where the equation of motion for the ith component q(i)(t) of the order parameter tensor is supplemented by a control term involving the difference q(i)(t)-q(i)(t-τ). In this diagonal scheme, τ is the delay time. We demonstrate that the TDFC method successfully stabilizes flow alignment for suitable values of the control strength K and τ; these values are determined by solving an exact eigenvalue equation. Moreover, our results show that only small values of K are needed when the system is sheared from an isotropic equilibrium state, contrary to the case where the equilibrium state is nematic. PMID:24483470

  13. Feedback control of flow alignment in sheared liquid crystals

    NASA Astrophysics Data System (ADS)

    Strehober, David A.; Schöll, Eckehard; Klapp, Sabine H. L.

    2013-12-01

    Based on a continuum theory, we investigate the manipulation of the nonequilibrium behavior of a sheared liquid crystal via closed-loop feedback control. Our goal is to stabilize a specific dynamical state, that is, the stationary "flow alignment," under conditions where the uncontrolled system displays oscillatory director dynamics with in-plane symmetry. To this end we employ time-delayed feedback control (TDFC), where the equation of motion for the ith component qi(t) of the order parameter tensor is supplemented by a control term involving the difference qi(t)-qi(t-τ). In this diagonal scheme, τ is the delay time. We demonstrate that the TDFC method successfully stabilizes flow alignment for suitable values of the control strength K and τ; these values are determined by solving an exact eigenvalue equation. Moreover, our results show that only small values of K are needed when the system is sheared from an isotropic equilibrium state, contrary to the case where the equilibrium state is nematic.

  14. Mass flow of a volatile organic liquid mixture in soils

    SciTech Connect

    Gerstl, Z.; Galin, Ts.; Yaron, B.

    1994-05-01

    The flow of kerosene, a volatile organic liquid mixture (VOLM), was studied in loam and clay soils and in a medium sand. The kerosene residual capacity and conductivity were determined for all three media at different initial moisture contents and with kerosene of different compositions. The kerosene conductivity of the soil was found to be strongly influenced by the soil texture and initial moisture content as well as by the kerosene composition. The kerosene conductivity of the sand was two orders of magnitude greater than that of the soils and was unaffected by initial moisture contents as high as field capacity. The kerosene conductivity of the loam soil was similar in oven dry and air dry soils, but increased significantly in soils at 70% and fun field capacity due to the Yuster effect. In the clay soil the kerosene conductivity of the air dry sod was four times that of the oven dry sod and increased somewhat in the soil at 70% field capacity. No kerosene flow was observed in the oven dry soil at full field capacity. The differences in kerosene conductivity in these soils and the effect of moisture content were attributed to the different pore-sin distributions of the soil& Changes in the composition of the kerosene due to volatilization of the light fractions resulted in increased viscosity of the residual kerosene. This increased viscosity affected the fluid properties of kerosene, which resulted in decreased kerosene conductivity in the sand and the soils. 29 refs., 4 figs., 4 tabs.

  15. Simulations of a Liquid Hydrogen Inducer at Low-Flow Off-Design Flow Conditions

    NASA Technical Reports Server (NTRS)

    Hosangadi, A.; Ahuja, V.; Ungewitter, R. J.

    2005-01-01

    The ability to accurately model details of inlet back flow for inducers operating a t low-flow, off-design conditions is evaluated. A sub-scale version of a three-bladed liquid hydrogen inducer tested in water with detailed velocity and pressure measurements is used as a numerical test bed. Under low-flow, off-design conditions the length of the separation zone as well as the swirl velocity magnitude was under predicted with a standard k-E model. When the turbulent viscosity coefficient was reduced good comparison was obtained a t all the flow conditions examined with both the magnitude and shape of the profile matching well with the experimental data taken half a diameter upstream of the leading edge. The velocity profiles and incidence angles a t the leading edge itself were less sensitive to the back flow length predictions indicating that single-phase performance predictions may be well predicted even if the details of flow separation modeled are incorrect. However, for cavitating flow situations the prediction of the correct swirl in the back flow and the pressure depression in the core becomes critical since it leads to vapor formation. The simulations have been performed using the CRUNCH CFD(Registered Trademark) code that has a generalized multi-element unstructured framework and a n advanced multi-phase formulation for cryogenic fluids. The framework has been validated rigorously for predictions of temperature and pressure depression in cryogenic fluid cavities and has also been shown to predict the cavitation breakdown point for inducers a t design conditions.

  16. Concentration studies of collision-induced fundamental absorption of hydrogen dissolved in liquid neon.

    PubMed

    Herrebout, W A; van der Veken, B J; Kouzov, A P

    2012-08-28

    We report further and more detailed results of our recent investigation [W. A. Herrebout, B. J. van der Veken, and A. P. Kouzov, Phys. Rev. Lett. 101, 093001 (2008)] on the collision-induced fundamental absorption by hydrogen dissolved in liquid neon (T ≈ 25 K). The band shapes were studied in a wide range of concentrations (0.003-0.05 mole fractions) as well as for different ortho/para ratios and at much higher level of accuracy and resolution than before. Due to almost unhindered rotation of the hydrogen molecule and low temperature, an unprecedently rich frequency-domain picture produced by different terms of the interaction-induced polarization was observed. While some of them are conspicuous via fast intracell motion of a light guest (H(2)), others--induced by the electrostatic field of the guest--give rise to lines whose shapes are imprinted by fluctuations of the nearest surrounding. Strong motional narrowing observed on the guest-guest induced lines shows up in their Lorentzian shapes which are signatures of microscopic-scale diffusion. Near-Lorentzian peaks were also detected at the tops of the diffuse lines induced by isolated guests. Their formation may be associated with a long-living defect (vacancy) emerging in the vicinity of the polarization inductor. Altogether, our results give the first unambiguous spectroscopic evidence on the diffusional evolution of isolated binary interactions that emerge in dense chaotic media. PMID:22938252

  17. Measurement of the Spectral Absorption of Liquid Water in Melting Snow With an Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the Earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. In this paper we present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation. the air temperature did not drop below freezing the night of the May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  18. Measurement of the spectral absorption of liquid water in melting snow with an imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Dozier, Jeff

    1995-01-01

    Melting of the snowpack is a critical parameter that drives aspects of the hydrology in regions of the earth where snow accumulates seasonally. New techniques for measurement of snow melt over regional scales offer the potential to improve monitoring and modeling of snow-driven hydrological processes. We present the results of measuring the spectral absorption of liquid water in a melting snowpack with the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). AVIRIS data were acquired over Mammoth Mountain, in east central California on 21 May 1994 at 18:35 UTC. The air temperature at 2926 m on Mammoth Mountain at site A was measured at 15-minute intervals during the day preceding the AVIRIS data acquisition. At this elevation, the air temperature did not drop below freezing the night of May 20 and had risen to 6 degrees Celsius by the time of the overflight on May 21. These temperature conditions support the presence of melting snow at the surface as the AVIRIS data were acquired.

  19. A measurement of the absorption of liquid argon scintillation light by dissolved nitrogen at the part-per-million level

    NASA Astrophysics Data System (ADS)

    Jones, B. J. P.; Chiu, C. S.; Conrad, J. M.; Ignarra, C. M.; Katori, T.; Toups, M.

    2013-07-01

    We report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of (1.51±0.15) × 10-4 cm-1ppm-1, corresponding to an absorption cross section of (4.99±0.51) × 10-21 cm2molecule-1. We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a current-generation LArTPC, where a concentration of 2 parts per million of nitrogen is expected, the attenuation length due to nitrogen will be 30±3 meters.

  20. IR multiphoton absorption of SF6 in flow with Ar at moderate energy fluences

    NASA Astrophysics Data System (ADS)

    Makarov, G. N.; Ronander, E.; van Heerden, S. P.; Gouws, M.; van der Merwe, K.

    1997-10-01

    IR multiple photon absorption (MPA) of SF6 in flow with Ar (SF6: Ar=1:100) in conditions of a large vibrational/rotational temperature difference (TV𪒮 K, TR䏐 K) was studied at moderate energy fluences from ۂ.1 to 𪐬 mJ/cm2, which are of interest for isotope selective two-step dissociation of molecules. A 50 cm Laval-type slit nozzle for the flow cooling, and a TEA CO2-laser for excitation of molecules were used in the experiments. The laser energy fluence dependences of the SF6 MPA were studied for several CO2-laser lines which are in a good resonance with the linear absorption spectrum of the Ƚ vibration of SF6 at low temperature. The effect of the laser pulse duration (intensity) on MPA of flow cooled SF6 with Ar was also studied. The results are compared with those obtained in earlier studies.

  1. Modeling of two-layer liquid-gas flow with account for evaporation

    NASA Astrophysics Data System (ADS)

    Goncharova, O. N.; Rezanova, E. V.; Lyulin, Yu. V.; Kabov, O. A.

    2015-09-01

    Two-layer gas-liquid flows and evaporation intensity at the interface were studied. The influence of gas flow rate, longitudinal gradient of temperature, the Soret effect on the nature of flow and transfer processes was demonstrated. Experimental and theoretical results were compared; they show dependence of evaporation at the interface on gas flow rates.

  2. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera

    NASA Astrophysics Data System (ADS)

    Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.

    2016-07-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics.

  3. Compact characterization of liquid absorption and emission spectra using linear variable filters integrated with a CMOS imaging camera

    PubMed Central

    Wan, Yuhang; Carlson, John A.; Kesler, Benjamin A.; Peng, Wang; Su, Patrick; Al-Mulla, Saoud A.; Lim, Sung Jun; Smith, Andrew M.; Dallesasse, John M.; Cunningham, Brian T.

    2016-01-01

    A compact analysis platform for detecting liquid absorption and emission spectra using a set of optical linear variable filters atop a CMOS image sensor is presented. The working spectral range of the analysis platform can be extended without a reduction in spectral resolution by utilizing multiple linear variable filters with different wavelength ranges on the same CMOS sensor. With optical setup reconfiguration, its capability to measure both absorption and fluorescence emission is demonstrated. Quantitative detection of fluorescence emission down to 0.28 nM for quantum dot dispersions and 32 ng/mL for near-infrared dyes has been demonstrated on a single platform over a wide spectral range, as well as an absorption-based water quality test, showing the versatility of the system across liquid solutions for different emission and absorption bands. Comparison with a commercially available portable spectrometer and an optical spectrum analyzer shows our system has an improved signal-to-noise ratio and acceptable spectral resolution for discrimination of emission spectra, and characterization of colored liquid’s absorption characteristics generated by common biomolecular assays. This simple, compact, and versatile analysis platform demonstrates a path towards an integrated optical device that can be utilized for a wide variety of applications in point-of-use testing and point-of-care diagnostics. PMID:27389070

  4. Electric current induced flow of liquid metals: Mechanism and substrate-surface effects

    SciTech Connect

    Kumar, P.; Howarth, J.; Dutta, I.

    2014-01-28

    Long range, continuous flow of liquid metals occurs upon application of an electric current. Here, we report experimental results elucidating the mechanism of current-induced liquid metal flow, and its dependence on substrate surface condition. It is shown that the observed flow is diffusion-controlled, with the flow-rate depending linearly on applied current density, indicating that it is driven by electromigration. The effective charge number for liquid electromigration, Z*, of several pure metals, such as Al, Bi, Ga, Sn, and Pb, were deduced from the experimental results and were found to be close to the elemental valency. With the exception of liquid Pb, Z* for all liquid metals tested in this study were positive, indicating that: (i) electron wind contributes much less to Z* in liquid metals than in solids, and (ii) with a few exceptions, liquid metals generally flow in the direction of the electric current. On smooth substrates which are wetted well by the liquid metal, flow occurs in a thin, continuous stream. On rough surfaces which are poorly wetted, on the other hand, discrete beads of liquid form, with mass transport between adjacent beads occurring by surface diffusion on the substrate. A rationale for the role of substrate roughness in fostering this observed transition in flow mechanism is presented.

  5. Experiment and computational simulations of liquid-liquid flow displacement in microchannels

    NASA Astrophysics Data System (ADS)

    Lu, Yu; Simmons, Mark

    2015-11-01

    Microfluidics has great potential for tight process control in the generation of high value-added products and there is a requirement to understand how one fluid displaces another for either cleaning or control of the interfacial phenomena. Micro-Particle Image Velocimetry (μ-PIV) and shadowgraphy have been used to examine the injection of a fluid into a circular or semi-circular microchannel (with diameters of 200 μm and 205 μm respectively) which is pre-filled with another fluid. Both immiscible and miscible Newtonian fluid pairs with varying viscosity ratio have been used. Flow instabilities and regimes have been observed which can be characterised using dimensionless flow maps. Displacement efficiency, residual liquid film thickness on the wall, velocity fields and the effect of wall conditions such as wall wettability are also studied. The flow phenomena observed have been modelled using the finite volume ANSYS Fluent CFD package and compared with the experiments. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  6. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    NASA Technical Reports Server (NTRS)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  7. The absorption coefficient of the liquid N2 2.15-micron band and application to Triton

    NASA Technical Reports Server (NTRS)

    Grundy, William M.; Fink, Uwe

    1991-01-01

    The present measurements of the temperature dependence exhibited by the liquid N2 2.15-micron 2-0 collision-induced band's absorption coefficient and integrated absorption show the latter to be smaller than that of the N2 gas, and to decrease with decreasing temperature. Extrapolating this behavior to Triton's nominal surface temperature yields a new estimate of the N2-ice grain size on the Triton south polar cap; a mean N2 grain size of 0.7-3.0 cm is consistent with grain growth rate calculation results.

  8. Experimental Investigation on Liquid Metal Flow Distribution in Insulating Manifold under Uniform Magnetic Field

    NASA Astrophysics Data System (ADS)

    Miura, Masato; Ueki, Yoshitaka; Yokomine, Takehiko; Kunugi, Tomoaki

    2012-11-01

    Magnetohydrodynamics (MHD) problem which is caused by interaction between electrical conducting fluid flow and the magnetic field is one of the biggest problem in the liquid metal blanket of the fusion reactor. In the liquid metal blanket concept, it is necessary to distribute liquid metal flows uniformly in the manifold because imbalance of flow rates should affect the heat transfer performance directly, which leads to safety problem. While the manifold is insulated electrically as well as the flow duct, the 3D-MHD effect on the flowing liquid metal in the manifold is more apparent than that in straight duct. With reference to the flow distribution in this concept, the liquid metal flow in the electrical insulating manifold under the uniform transverse magnetic field is investigated experimentally. In this study, GaInSn is selected as working fluid. The experimental system includes the electrical magnet and the manifold test section which is made of acrylic resin for perfectly electrical insulation. The liquid metal flows in a non-symmetric 180°-turn with manifold, which consists of one upward channel and two downward channels. The flow rates in each channel are measured by electromagnetic flow meters for several combinations Reynolds number and Hartman number. The effects of magnetic field on the uniformity of flow distribution are cleared.

  9. Investigation of flow and microstructure in rheometric and processing flow conditions for liquid crystalline pitch

    NASA Astrophysics Data System (ADS)

    Kundu, Santanu

    The microstructure development within mesophase pitch-based carbon materials depends on the flow history that the pitch is subjected to. Therefore, a fundamental understanding of flow and its influence on the microstructure is required to obtain carbon materials with desired properties. The objective of this research was to investigate the flow and microstructural behavior of a synthetic mesophase pitch (AR-HP) in rheometric and processing flow conditions. In addition, simulation studies were performed to establish a frame work for modeling the flow behavior of this complex material in different flow situations. The steady-shear viscosities obtained from a cone-plate rheometer during increasing rate-sweep experiments exhibited shear-thinning (Region I) and plateau (Region II) responses. However, the slope of the shear-thinning region was only about -0.2, much lower than -0.5 observed in some pitches and liquid-crystalline polymers. This difference could arise from the different molecular constituents of pitches. At higher shear rates, as measured from capillary rheometers, the viscosity values remained almost constant. The transient shear stress responses, as measured from cone-plate rheometer, exhibited nonmonotonic behavior as a function of applied strain at all shear rates and temperatures tested. After rheological experiments, the samples were collected by developing a new experimental protocol for preservation of the sample for microstructural analysis. Microstructural observations obtained from three orthogonal sections, reported for the first time in the literature, indicate that the local maximum in shear stress was due to yielding of initial microstructure. The microstructure became flow oriented with further shearing, and the structure size decreased with increasing shear rates. In addition to high-strain experiments, dynamic experiments were also performed in the linear viscoelastic region where no significant deformation of fluid takes place. The

  10. Effect of surface condition on the flow in segmented gas-liquid microreactors

    NASA Astrophysics Data System (ADS)

    Pouya, Shahram; Koochesfahani, Manoochehr

    2010-11-01

    The mixing process within segmented gas-liquid microreactors is of significance importance in design and optimization of devices for high throughput material synthesis. In a typical slug flow regime the liquid slugs are connected through a thin liquid film that plays an important role in hydrodynamics of the microreactor flow. Among the parameters that can influence the thin film layer, and the overall flow, is the surface condition of microchannel walls. We present preliminary results of this influence in the segmented gas-liquid flow of Ethanol/Nitrogen within PDMS microreactors. The results are presented specifically for microreactors with different level of roughness on the channel walls. The range of stable slug flow regime and behavior of liquid film are studied as a function of surface roughness.

  11. Insulin absorption and subcutaneous blood flow in normal subjects during insulin-induced hypoglycemia

    SciTech Connect

    Fernqvist-Forbes, E.; Linde, B.; Gunnarsson, R.

    1988-09-01

    We studied the effects of insulin-induced hypoglycemia on the absorption of 10 U /sup 125/I-labeled soluble human insulin injected sc in the thigh in 10 normal subjects. The disappearance of /sup 125/I from the injection site was followed by external gamma-counting. Subcutaneous blood flow (ATBF) was measured concomitantly with the 133Xe washout technique. The plasma glucose nadir (mean, 2.0 +/- 0.1 (+/- SE) mmol/L) occurred at 33 +/- 3 min and resulted in maximal arterial plasma epinephrine concentrations of approximately 6 nmol/L. From 30 min before to 60 min after the glucose nadir the (/sup 125/I)insulin absorption rate was depressed compared to that during normoglycemia. The first order disappearance rate constants were reduced by approximately 50% (P less than 0.01) during the first 30-min interval after the glucose nadir. During the same period ATBF increased by 100% (P less than 0.05). The results suggest that in normal subjects the absorption of soluble insulin from a sc depot is depressed in connection with hypoglycemia, despite considerably elevated ATBF.

  12. Special Features in Application of Nuclear Magnetic Spectroscopy to Study Flows of Liquid Media

    NASA Astrophysics Data System (ADS)

    Davydov, V. V.; Dudkin, V. I.; Karseev, A. Yu.; Vologdin, V. A.

    2016-01-01

    We consider the special features involved in studying flows of liquid media using a nuclear magnetic resonance spectrometer. Taking these special features into account in the design of the NMR spectrometer lets us determine the relative concentrations of paramagnetic ions, and also lets us measure the longitudinal (T1 ) and transverse (T2 ) relaxation times within <0.5% in liquid flows. This lets us completely eliminate errors in determining the state of the flowing medium using the measured relaxation constants T1 and T2, which is especially important when working with medicinal suspensions and biological solutions. We present the results of experimental studies on flows of liquid media.

  13. Modeling the Interface Instability and Mixing Flow During the Process of Liquid Explosion Dissemination

    NASA Astrophysics Data System (ADS)

    Li, L.; Xu, S. L.; Ren, Y. J.; Liu, G. R.; Ren, X. B.; Xie, W. J.; Li, Y. C.; Wang, Z. L.

    The liquid flow during the process of liquid explosion dissemination is a typical complex high-speed unsteady motion with multi-scale in space and time. The motion of liquid flow may be partitioned to several stages. The first is initial liquid expansion by the action of shock wave and explosive gaseous products. The second is breakup of liquid annulus and turbulent mixing, which is called near-field flow. The third is two-phase mixing flow of gas and liquid drops, which is called far-field flow. To first stage, a compressible inviscid liquid model was used, while an elastic and plastic model was used to depict the expansion of solid shell. Numerical study in two dimensional has been made by using the Arbitrary Euler-Lagrange (ALE) methods. In near-field, the unstable flow of liquid annulus is dominated by many factors. (1) The shock action of gaseous expansive products. (2) The geometric structure of wave system in liquid. (3) The local bubble and cavitating flow in annulus, induce much of local unstable interface, tear up interfaces, and enhance the instability and breakup of liquid annulus. In this paper, some postulations are proposed that the cavitations in liquid annulus are induced by shock wave and the flow of liquid annulus is a two phase flow (liquid and a discrete bubble groups). Some experimental results will be presented that the breakup of interface and turbulent mixing is visualized qualitatively and measured quantitatively by using shadow photography method. The primary results are some flow patten of interfaces and some transient flow parameters by which the nonlinear character will be obtained, and provide an experiential support for modeling to unstable interface flow and turbulent mixing. The two-phase mixing flow between liquid drops and gas in far-field can be studied by numerical methods where the turbulent motion of gas phase is represented with k-ɛ model in Euler system, the motion of particle phase is represented with particle stochastic

  14. Multi-Molar Absorption of CO2 by the Activation of Carboxylate Groups in Amino Acid Ionic Liquids.

    PubMed

    Chen, Feng-Feng; Huang, Kuan; Zhou, Yan; Tian, Zi-Qi; Zhu, Xiang; Tao, Duan-Jian; Jiang, De-En; Dai, Sheng

    2016-06-13

    A new strategy for multi-molar absorption of CO2 is reported based on activating a carboxylate group in amino acid ionic liquids. It was illustrated that introducing an electron-withdrawing site to amino acid anions could reduce the negative inductive effect of the amino group while simultaneously activating the carboxylate group to interact with CO2 very efficiently. An extremely high absorption capacity of CO2 (up to 1.69 mol mol(-1) ) in aminopolycarboxylate-based amino acid ionic liquids was thus achieved. The evidence of spectroscopic investigations and quantum-chemical calculations confirmed the interactions between two kinds of sites in the anion and CO2 that resulted in superior CO2 capacities. PMID:27136274

  15. Equation of DNB Heat Flux for Upward Forced Flow of Cryogenic Liquids

    NASA Astrophysics Data System (ADS)

    Shiotsu, M.; Tatsumoto, H.; Shirai, Y.; Hata, K.; Naruo, Y.; Kobayashi, H.; Inatani, Y.; Kinoshita, K.

    Knowledge of departure from nucleate boiling (DNB) heat flux is important for design of superconducting systems cooled by cryogenic liquids. We have already presented the equation of DNB heat flux that can describe the experimental data of liquid hydrogen. To see the applicability of the equation to other cryogenic liquids, similar heat transfer tests in forced flow of liquid nitrogen are performed for wide ranges of conditions in this work. It was confirmed that the DNB heat flux equation derived by the authors can express not only the data for liquid hydrogen but also those for liquid nitrogen.

  16. Control of Flowing Liquid Films by Electrostatic Fields in Space

    NASA Technical Reports Server (NTRS)

    Griffing, E. M.; Bankoff, S. G.; Schluter, R. A.; Miksis, M. J.

    1999-01-01

    The interaction of a spacially varying electric field and a flowing thin liquid film is investigated experimentally for the design of a proposed light weight space radiator. Electrodes are utilized to create a negative pressure at the bottom of a fluid film and suppress leaks if a micrometeorite punctures the radiator surface. Experimental pressure profiles under a vertical falling film, which passes under a finite electrode, show that fields of sufficient strength can be used safely in such a device. Leak stopping experiments demonstrate that leaks can be stopped with an electric field in earth gravity. A new type of electrohydrodynamic instability causes waves in the fluid film to develop into 3D cones and touch the electrode at a critical voltage. Methods previously used to calculate critical voltages for non moving films are shown to be inappropriate for this situation. The instability determines a maximum field which may be utilized in design, so the possible dependence of critical voltage on electrode length, height above the film, and fluid Reynolds number is discussed.

  17. Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water

    SciTech Connect

    Nordlund, D

    2012-02-14

    We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

  18. Low-Dimensional Water on Ru(0001); Model System for X-ray Absorption Spectroscopy Studies of Liquid Water

    SciTech Connect

    Nordlund, D.; Ogasawara, H.; Andersson, K.J.; Tatarkhanov, M.; Salmeron, M.; Pettersson, L. G. M.; Nilsson, A.

    2009-05-11

    We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

  19. Experimental investigation of non-Newtonian/Newtonian liquid-liquid flow in microchannel

    NASA Astrophysics Data System (ADS)

    Roumpea, Eynagelia-Panagiota; Weheliye, Weheliye; Chinaud, Maxime; Angeli, Panagiota; Lyes Kahouadji Collaboration; Omar. K. Matar Collaboration

    2015-11-01

    Plug flow of an organic phase and an aqueous non-Newtonian solution was investigated experimentally in a quartz microchannel with I.D. 200 μm. The aqueous phase was a glycerol solution where 1000 and 2000 ppm of xanthan gum was added while the organic phase was silicon oil with 155 and 5 cSt viscosity. The two phases were brought together in a T-junction and their flowrates varied from 0.3 to 6 ml/hr. High speed imaging was used to study the characteristics of the plugs and the effect of the liquid properties on the flow patterns while a two-colour micro-PIV technique was used to investigate velocity profiles and circulation patterns within the plugs. The experimental results revealed that plug length was affected by both flowrate and viscosity. In all cases investigated, a film of the continuous phase always surrounded the plugs and its thickness was compared with existing literature models. Circulation patterns inside plugs were obtained by subtracting the plug velocity and found to be depended on the plug length and the amount of xanthan gum in the aqueous phase. Finally, the dimensionless circulation time was calculated and plotted as a function of the plug length. Department of Chemical Engineering South Kensington Campus Imperial College London SW7 2AZ.

  20. Centrifugal contactor with liquid mixing and flow control vanes and method of mixing liquids of different phases

    SciTech Connect

    Jubin, R.T.; Randolph, J.D.

    1991-06-18

    This patent describes a centrifugal contactor for solvent extraction systems. The centrifugal contactor is provided with an annular vertically oriented mixing chamber between the rotor housing and the rotor for mixing process liquids such as the aqueous and organic phases of the solvent extraction process used for nuclear fuel reprocessing. A set of stationary helically disposed vanes carried by the housing is in the lower region of the mixing chamber at a location below the process-liquid inlets for the purpose of urging the liquids in an upward direction toward the inlets and enhancing the mixing of the liquids and mass transfer between the liquids. The upper region of the mixing vessel above the inlets for the process liquids is also provided with a set helically disposed vanes carried by the housing for urging the process liquids in a downward direction when the liquid flow rates through the inlets are relatively high and the liquids contact the vane set in the upper region. The use of these opposing vane sets in the mixing zone maintains the liquid in the mixing zone at suitable levels.

  1. Observations of Gas-Liquid Flows Through Contractions in Microgravity

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    1996-01-01

    Tests were conducted for an air-water flow through two sudden contractions aboard the NASA DC-9 low gravity aircraft. Flow rate, residual accelerations, void fraction, film thickness, and pressure drop data were recorded and flow visualization at 250 images per second were recorded. Some preliminary results based on the flow visualization data are presented for bubbly, slug and annular flow.

  2. Large-Flow-Area Flow-Selective Liquid/Gas Separator

    NASA Technical Reports Server (NTRS)

    Vasquez, Arturo; Bradley, Karla F.

    2010-01-01

    This liquid/gas separator provides the basis for a first stage of a fuel cell product water/oxygen gas phase separator. It can separate liquid and gas in bulk in multiple gravity environments. The system separates fuel cell product water entrained with circulating oxygen gas from the outlet of a fuel cell stack before allowing the gas to return to the fuel cell stack inlet. Additional makeup oxygen gas is added either before or after the separator to account for the gas consumed in the fuel cell power plant. A large volume is provided upstream of porous material in the separator to allow for the collection of water that does not exit the separator with the outgoing oxygen gas. The water then can be removed as it continues to collect, so that the accumulation of water does not impede the separating action of the device. The system is designed with a series of tubes of the porous material configured into a shell-and-tube heat exchanger configuration. The two-phase fluid stream to be separated enters the shell-side portion of the device. Gas flows to the center passages of the tubes through the porous material and is then routed to a common volume at the end of the tubes by simple pressure difference from a pumping device. Gas flows through the porous material of the tubes with greater ease as a function of the ratio of the dynamic viscosity of the water and gas. By careful selection of the dimensions of the tubes (wall thickness, porosity, diameter, length of the tubes, number of the tubes, and tube-to-tube spacing in the shell volume) a suitable design can be made to match the magnitude of water and gas flow, developed pressures from the oxygen reactant pumping device, and required residual water inventory for the shellside volume.

  3. MHD Effect of Liquid Metal Film Flows as Plasma-Facing Components

    NASA Astrophysics Data System (ADS)

    Zhang, Xiujie; Xu, Zengyu; Pan, Chuanjie

    2008-12-01

    Stability of liquid metal film flow under gradient magnetic field is investigated. Three dimensional numerical simulations on magnetohydrodynamics (MHD) effect of free surface film flow were carried out, with emphasis on the film thickness variation and its surface stability. Three different MHD phenomena of film flow were observed in the experiment, namely, retardant, rivulet and flat film flow. From our experiment and numerical simulation it can be concluded that flat film flow is a good choice for plasma-facing components (PFCs)

  4. A visual study of radial inward choked flow of liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Simoneau, R. J.; Hsu, Y. Y.

    1973-01-01

    A visual study of the radial inward choked flow of liquid nitrogen was conducted. Data and high speed moving pictures were obtained. The study indicated the following: (1) steady radial inward choked flow seems equivalent to steady choked flow through axisymmetric nozzles, (2) transient choked flows through the radial gap are not uniform and the discharge pattern appears as nonuniform impinging jets, and (3) the critical mass flow rate data for the transient case appear different from those of the steady case.

  5. Versatile plug flow catalytic cell for in situ transmission/fluorescence x-ray absorption fine structure measurements

    SciTech Connect

    Centomo, P.; Zecca, M.; Meneghini, C.

    2013-05-15

    A novel flow-through catalytic cell has been developed for in situ x-ray absorption spectroscopy (XAS) experiments on heterogeneous catalysts under working conditions and in the presence of a liquid and a gas phase. The apparatus allows to carry out XAS measurements in both the transmission and fluorescence modes, at moderate temperature (from RT to 50-80 Degree-Sign C) and low-medium gas pressure (up to 7-8 bars). The materials employed are compatible with several chemicals such as those involved in the direct synthesis of hydrogen peroxide (O{sub 2}, H{sub 2}, H{sub 2}O{sub 2}, methanol). The versatile design of the cell allows to fit it to different experimental setups in synchrotron radiation beamlines. It was used successfully for the first time to test nanostructured Pd catalysts during the direct synthesis of hydrogen peroxide (H{sub 2}O{sub 2}) in methanol solution from dihydrogen and dioxygen.

  6. Investigation of the Extinguishing Features for Liquid Fuels and Organic Flammable Liquids Atomized by a Water Flow

    NASA Astrophysics Data System (ADS)

    Voytkov, Ivan V.; Zabelin, Maksim V.; Vysokomornaya, Olga V.

    2016-02-01

    The processes of heat and mass transfer were investigated experimentally while moving and evaporating the atomized water flow in high-temperature combustion products of typical liquid fuels and organic flammable liquids: gasoline, kerosene, acetone, crude oil, industrial alcohol. We determined typical periods of liquid extinguishing by an atomized water flow of various dispersability. Data of the discharge of extinguishing medium corresponding to various parameters of atomization and duration of using the atomization devices was presented. It is shown that Um≈3.5 m/s is a minimal outflow velocity of droplets during moving while passing the distance of 1m in the high-temperature gas medium to stop the combustion of organic liquids.

  7. Liquid methane gelled with methanol and water reduces rate of nitrogen absorption

    NASA Technical Reports Server (NTRS)

    Vanderwall, E. M.

    1972-01-01

    Dilution of gelant vapor with inert carrier gas accomplishes gelation. Mixture is injected through heated tube and orifice into liquid methane for immediate condensation within bulk of liquid. Direct dispersion of particles in liquid avoids condensation on walls of vessel and eliminates additional mixing.

  8. Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

    2001-01-01

    This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

  9. The Effects of Void Geometry and Contact Angle on the Absorption of Liquids into Porous Calcium Carbonate Structures.

    PubMed

    Ridgway, Cathy J.; Schoelkopf, Joachim; Matthews, G. Peter; Gane, Patrick A. C.; James, Philip W.

    2001-07-15

    The absorption (permeation) of alcohols into porous blocks of calcium carbonate has been studied experimentally and with a computer model. The experimental measurement was of change in apparent weight of a block with time after contact with liquid. The modeling used the previously developed 'Pore-Cor' model, based on unit cells of 1000 cubic pores connected by cylindrical throats. To gain some insight into absorption into voids of complex geometry, and to provide a representation of heterogeneities in surface interaction energy, the cylindrical throats were converted to double cones. Relative to cylinders, such geometries caused hold-ups of the percolation of nonwetting fluids with respect to increasing applied pressure, and a change in the rate of absorption of wetting fluids. Both the measured absorption of the alcohols and the simulated absorption of the alcohols and of water showed significant deviations from that predicted by an effective hydraulic radius approximation. The simulation demonstrated the development of a highly heterogeneous wetting front, and of preferred wetting pathways that were perturbed by inertial retardation. The findings are useful in the design of high-performance, low-waste pigments for paper coatings, and environmentally friendly printing inks, as well as in wider industrial, environmental, and geological contexts. Copyright 2001 Academic Press. PMID:11427007

  10. Flow and temperature field measurements of thermal convection in a small vertical gap using liquid crystals

    NASA Astrophysics Data System (ADS)

    Heiland, Hans Georg; Wozniak, Günter; Wozniak, Klaus

    2007-07-01

    Thermal convection in a small vertical gap is studied experimentally applying digital particle image velocimetry/thermometry. This optical method enables the simultaneous measurement of two-dimensional flow and temperature fields in a liquid. The principle is based on seeding the liquid flow medium with thermochromic liquid crystal particles. The temperature is measured by the crystal particles which change their reflected colour as function of temperature. The flow velocity is measured by using the same particles as flow tracers. The investigation shall contribute to the understanding of the fluid mechanical behaviour of biological liquids within micro reactor systems. However, the problem is also of fundamental interest as far as heat and mass transfer is concerned. Measured temperature and flow velocity fields are presented and discussed.

  11. Velocity Vector Field Visualization of Flow in Liquid Acquisition Device Channel

    NASA Technical Reports Server (NTRS)

    McQuillen, John B.; Chao, David F.; Hall, Nancy R.; Zhang, Nengli

    2012-01-01

    A capillary flow liquid acquisition device (LAD) for cryogenic propellants has been developed and tested in NASA Glenn Research Center to meet the requirements of transferring cryogenic liquid propellants from storage tanks to an engine in reduced gravity environments. The prototypical mesh screen channel LAD was fabricated with a mesh screen, covering a rectangular flow channel with a cylindrical outlet tube, and was tested with liquid oxygen (LOX). In order to better understand the performance in various gravity environments and orientations at different liquid submersion depths of the screen channel LAD, a series of computational fluid dynamics (CFD) simulations of LOX flow through the LAD screen channel was undertaken. The resulting velocity vector field visualization for the flow in the channel has been used to reveal the gravity effects on the flow in the screen channel.

  12. Cross-flow heat exchangers for anti-freezing of liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Chang, Ho-Myung; Gwak, Kyung Hyun; Yang, Hyung Suk; Hwang, Si-Dole

    2013-10-01

    Cross-flow heat exchangers are proposed and experimentally investigated as an anti-freezing scheme of liquid nitrogen. The possibility of freeze-out of liquid nitrogen is an important design issue in developing long superconducting cables, as the supply temperature of liquid nitrogen is close to its freezing temperature (63.3 K). Plate-fin heat exchangers are fabricated as typical counter-flow and newly proposed two-pass cross-flow in laboratory scale, and tested with cold helium gas at temperatures below 60 K. The experimental results show that the cross-flow heat exchanger is less vulnerable to the freeze-out condition, since the temperature distribution is basically two-dimensional. The cross-flow heat exchangers are effective in avoiding a complete clog-up of all passages and reducing the risk of freeze-out of liquid nitrogen.

  13. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    NASA Astrophysics Data System (ADS)

    Hoffman, A. S.; Debefve, L. M.; Bendjeriou-Sedjerari, A.; Ouldchikh, S.; Bare, Simon R.; Basset, J.-M.; Gates, B. C.

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  14. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres.

    PubMed

    Hoffman, A S; Debefve, L M; Bendjeriou-Sedjerari, A; Ouldchikh, S; Bare, Simon R; Basset, J-M; Gates, B C

    2016-07-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities-to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions-to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported. PMID:27475549

  15. Measuring the rate of local evaporation from the liquid surface under the action of gas flow

    NASA Astrophysics Data System (ADS)

    Lyulin, Yu. V.; Feoktistov, D. V.; Afanas'ev, I. A.; Chachilo, E. S.; Kabov, O. A.; Kuznetsov, G. V.

    2015-07-01

    The dynamics of evaporation from the surface of a liquid layer under the action of a gas flow has been studied. Correlation dependences of the rate of liquid evaporation on the gas flow rate and temperature for the ethanol-air system have been obtained and compared to other published experimental data. It is established that, for the two-phase systems studied, the evaporation rate growth with increasing temperature exhibits an almost identical character independently of the thermal properties of particular liquids and gases. In contrast, the character of the evaporation rate growth with increasing gas flow velocity significantly depends on these properties.

  16. Effect of ambient pressure on liquid swirl injector flow dynamics

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Yang, Vigor

    2014-10-01

    In this paper, a combined theoretical and numerical analysis is performed to study the internal and external flowfields of a liquid swirl injector. The effect of ambient pressure on the injector dynamics is explored systematically over a range of 1-50 atm. An increase in the ambient pressure increases the liquid film thickness, but decreases the spreading angle. This phenomenon can be attributed to the modification of the velocity profiles within the liquid film near the gas-liquid interface due to the alteration of the gas-phase shear stresses with pressure. The friction force at the interface plays a minor role. The generation and existence of stationary waves in the injector nozzle is also considered. At a higher ambient pressure, the pressure drop across the liquid sheet downstream of the injector exit increases, thereby suppressing the spreading of the liquid sheet. This in turn increases the thickness of the liquid sheet, and subsequently increases the breakup length at higher pressure. A semi-empirical model is developed to relate the velocity and pressure distributions near the surface of the liquid sheet. Good agreement is achieved between the measured and predicted shape and spreading angle of the liquid sheet.

  17. An electrochemical flow-cell for permanent modification of graphite tube with palladium for mercury determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Moreno, Ruben G. M.; de Oliveira, Elisabeth; Pedrotti, Jairo J.; Oliveira, Pedro V.

    2002-04-01

    An electrochemical procedure for palladium deposition on the inner surface of pyrolytic graphite-coated tubes for permanent chemical modification and a cold vapor generation system for the pre-concentration and determination of mercury trace levels in rain, potable, and non-potable water and lake sediment by electrothermal atomic absorption spectrometry is proposed. A tubular electrochemical flow-cell was assembled on the original geometry of the graphite tube, which operated as the working electrode. A stainless steel tube, positioned downstream from the working electrode, was used as the auxiliary electrode. The applied potential was measured against a micro Ag/AgCl (sat) reference electrode inserted in the auxiliary electrode. Palladium solution in acetate buffer (100 mmol l -1, pH=4.8), flowing at 0.5 ml min -1 for 60 min was used to perform the electrodeposition. A homemade cold vapor generation system composed of a peristaltic pump, an injector-commutator, a flow meter and a disposable polyethylene gas-liquid separator flask (approx. 4.0 ml volume) were used. Volumes of 1.0 ml of reagent (2.0% w/v NaBH 4 in 0.10 mol l -1 of NaOH) and 1.0 ml of reference or sample solution in 0.25 mol l -1 of HNO 3 were carried to the gas-liquid separator using the peristaltic pump. The mercury vapor was carried out to the modified graphite tube by argon flow (200 ml min -1), and pre-concentrated for 120 s. The characteristic mass for 1.0 ml of reference solution was 26 pg (R.S.D.=0.12%, n=5). The detection limit obtained was 93 pg ( n=20, 3δ). The reliability of the entire procedure was confirmed by addition and recovery tests and cold vapor atomic absorption spectrometry.

  18. A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    McQuillen, J.

    2000-01-01

    The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and

  19. Theoretical study of the effect of liquid desiccant mass flow rate on the performance of a cross flow parallel-plate liquid desiccant-air dehumidifier

    NASA Astrophysics Data System (ADS)

    Mohammad, Abdulrahman Th.; Mat, Sohif Bin; Sulaiman, M. Y.; Sopian, K.; Al-abidi, Abduljalil A.

    2013-11-01

    A computer simulation using MATLAB is investigated to predict the distribution of air stream parameters (humidity ratio and temperature) as well as desiccant parameters (temperature and concentration) inside the parallel plate absorber. The present absorber consists of fourteen parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal and dehumidifier effectiveness). Performance comparisons between present cross-flow dehumidifier and another experimental cross-flow dehumidifier in the literature are carried out. The simulation is expected to help in optimizing of a cross flow dehumidifier.

  20. High average power laser using a transverse flowing liquid host

    DOEpatents

    Ault, Earl R.; Comaskey, Brian J.; Kuklo, Thomas C.

    2003-07-29

    A laser includes an optical cavity. A diode laser pumping device is located within the optical cavity. An aprotic lasing liquid containing neodymium rare earth ions fills the optical cavity. A circulation system that provides a closed loop for circulating the aprotic lasing liquid into and out of the optical cavity includes a pump and a heat exchanger.

  1. High throughput analysis of samples in flowing liquid

    DOEpatents

    Ambrose, W. Patrick; Grace, W. Kevin; Goodwin, Peter M.; Jett, James H.; Orden, Alan Van; Keller, Richard A.

    2001-01-01

    Apparatus and method enable imaging multiple fluorescent sample particles in a single flow channel. A flow channel defines a flow direction for samples in a flow stream and has a viewing plane perpendicular to the flow direction. A laser beam is formed as a ribbon having a width effective to cover the viewing plane. Imaging optics are arranged to view the viewing plane to form an image of the fluorescent sample particles in the flow stream, and a camera records the image formed by the imaging optics.

  2. Pumping of Dielectric Liquids Using Non-Uniform-Field Induced Electrohydrodynamic Flow

    NASA Astrophysics Data System (ADS)

    Ryu, Jae Chun; Kim, Wonkyoung; Kang, Kwan Hyoung

    2010-11-01

    Pumping of dielectric liquids or poorly conducting liquids is necessary in cooling of microelectronic devices, dispensing liquids in miniature systems for chemical and biological analysis, and micropumping of organic solvents for microreactor. Electrical pumping of liquids is more attractive than conventional mechanical pumping methods because of many advantages such as simple design, no mechanical parts, low acoustic noise, and lightweight. We present a new electrohydrodynamic (EHD) pumping method for dielectric liquids. The pumping method relies on the EHD flow generated by electric-field dependent electrical conductivity (Onsager effect). A polar additive plays an important role in enhancing the field-dependency of conductivity. When ac voltage is applied, a fast and regular flow was produced around electrodes. Flow speed is proportional to cube of electric-field strength and inversely to applied frequency. The experimental results showed good agreement with numerical analysis which is based on our model.

  3. Flowmeter for determining average rate of flow of liquid in a conduit

    DOEpatents

    Kennerly, John M.; Lindner, Gordon M.; Rowe, John C.

    1982-01-01

    This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

  4. Flowmeter for determining average rate of flow of liquid in a conduit

    DOEpatents

    Kennerly, J.M.; Lindner, G.M.; Rowe, J.C.

    1981-04-30

    This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

  5. Cortical shell-liquid core model for passive flow of liquid-like spherical cells into micropipets.

    PubMed Central

    Yeung, A; Evans, E

    1989-01-01

    Many nonadherent cells exist as spheres in suspension and when sucked into pipets, deform continuously like liquids within the fixed surface area limitation of a plasma membrane envelope. After release, these cells eventually recover their spherical form. Consequently, pipet aspiration test provides a useful method to assay the apparent viscosity of such cells. For this purpose, we have analyzed the inertialess flow of a liquid-like model cell into a tube at constant suction pressure. The cell is modeled as a uniform liquid core encapsulated by a distinct cortical shell. The method of analysis employs a variational approach that minimizes errors in boundary conditions defined by the equations of motion for the cortical shell where the trial functions are exact solutions for the flow field inside the liquid core. For the particular case of an anisotropic liquid cortex with persistent tension, we have determined universal predictions for flow rate scaled by the ratio of excess pressure (above the threshold established by the cortical tension) and core viscosity which is the reciprocal of the dynamic resistance to entry. The results depend on pipet to cell size ratio and a parameter that characterizes the ratio of viscous flow resistance in the cortex to that inside the cytoplasmic core. The rate of entry increases markedly as the pipet size approaches the outer segment diameter of the cell. Viscous dissipation in the cortex strongly influences the entry flow resistance for small tube sizes but has little effect for large tubes. This indicates that with sufficient experimental resolution, measurement of cell entry flow with different-size pipets could establish both the cortex to cell dissipation ratio as well as the apparent viscosity of the cytoplasmic core. Images FIGURE 1 PMID:2752083

  6. Drainage of the air film during drop impact on flowing liquid films

    NASA Astrophysics Data System (ADS)

    Che, Zhizhao; Matar, Omar

    2015-11-01

    Immediately upon the impact of a droplet on a liquid or a solid, a thin air cushion is formed by trapping air beneath the droplet. The drainage of the air film is critical in determining the eventual outcome of the impact. Here we propose a model to study the drainage of the gas film between a droplet and a flowing liquid film. The effects of a wide range of parameters influencing the drainage process are studied, such as the fluid viscosities, the surface tension, the velocity of the droplet, the velocity of the liquid film. The results show that the tangential movement of the liquid film can delay the drainage of the air film and promote the bouncing of droplets. This confirms our previous experimental results, which show that during the impact of droplets on flow liquid films, the probability of bouncing increases with the Reynolds number of the liquid film. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  7. On the Motion of an Annular Film in Microgravity Gas-Liquid Flow

    NASA Technical Reports Server (NTRS)

    McQuillen, John B.

    2002-01-01

    Three flow regimes have been identified for gas-liquid flow in a microgravity environment: Bubble, Slug, and Annular. For the slug and annular flow regimes, the behavior observed in vertical upflow in normal gravity is similar to microgravity flow with a thin, symmetrical annular film wetting the tube wall. However, the motion and behavior of this film is significantly different between the normal and low gravity cases. Specifically, the liquid film will slow and come to a stop during low frequency wave motion or slugging. In normal gravity vertical upflow, the film has been observed to slow, stop, and actually reverse direction until it meets the next slug or wave.

  8. Flow pattern changes influenced by variation of viscosities of a heterogeneous gas-liquid mixture flow in a vertical channel

    SciTech Connect

    Keska, Jerry K.; Hincapie, Juan; Jones, Richard

    2011-02-15

    In the steady-state flow of a heterogeneous mixture such as an air-liquid mixture, the velocity and void fraction are space- and time-dependent parameters. These parameters are the most fundamental in the analysis and description of a multiphase flow. The determination of flow patterns in an objective way is extremely critical, since this is directly related to sudden changes in spatial and temporal changes of the random like characteristic of concentration. Flow patterns can be described by concentration signals in time, amplitude, and frequency domains. Despite the vital importance and countless attempts to solve or incorporate the flow pattern phenomena into multiphase models, it has still been a very challenging topic in the scientific community since the 1940's and has not yet reached a satisfactory solution. This paper reports the experimental results of the impact of fluid viscosity on flow patterns for two-phase flow. Two-phase flow was created in laboratory equipment using air and liquid as phase medium. The liquid properties were changed by using variable concentrations of glycerol in water mixture which generated a wide-range of dynamic viscosities ranging from 1 to 1060 MPa s. The in situ spatial concentration vs. liquid viscosity and airflow velocity of two-phase flow in a vertical ID=50.8 mm pipe were measured using two concomitant computer-aided measurement systems. After acquiring data, the in situ special concentration signals were analyzed in time (spatial concentration and RMS of spatial concentration vs. time), amplitude (PDF and CPDF), and frequency (PSD and CPSD) domains that documented broad flow pattern changes caused by the fluid viscosity and air velocity changes. (author)

  9. Bubble Formation from Wall Orifice in Liquid Cross-Flow Under Low Gravity

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kamotani, Y.

    2000-01-01

    Two-phase flows present a wide variety of applications for spacecraft thermal control systems design. Bubble formation and detachment is an integral part of the two phase flow science. The objective of the present work is to experimentally investigate the effects of liquid cross-flow velocity, gas flow rate, and orifice diameter on bubble formation in a wall-bubble injection configuration. Data were taken mainly under reduced gravity conditions but some data were taken in normal gravity for comparison. The reduced gravity experiment was conducted aboard the NASA DC-9 Reduced Gravity Aircraft. The results show that the process of bubble formation and detachment depends on gravity, the orifice diameter, the gas flow rate, and the liquid cross-flow velocity. The data are analyzed based on a force balance, and two different detachment mechanisms are identified. When the gas momentum is large, the bubble detaches from the injection orifice as the gas momentum overcomes the attaching effects of liquid drag and inertia. The surface tension force is much reduced because a large part of the bubble pinning edge at the orifice is lost as the bubble axis is tilted by the liquid flow. When the gas momentum is small, the force balance in the liquid flow direction is important, and the bubble detaches when the bubble axis inclination exceeds a certain angle.

  10. Bubble formation during horizontal gas injection into downward-flowing liquid

    NASA Astrophysics Data System (ADS)

    Bai, Hua; Thomas, Brian G.

    2001-12-01

    Bubble formation during gas injection into turbulent downward-flowing water is studied using high-speed videos and mathematical models. The bubble size is determined during the initial stages of injection and is very important to turbulent multiphase flow in molten-metal processes. The effects of liquid velocity, gas-injection flow rate, injection hole diameter, and gas composition on the initial bubble-formation behavior have been investigated. Specifically, the bubble-shape evolution, contact angles, size, size range, and formation mode are measured. The bubble size is found to increase with increasing gas-injection flow rate and decreasing liquid velocity and is relatively independent of the gas injection hole size and gas composition. Bubble formation occurs in one of four different modes, depending on the liquid velocity and gas flow rate. Uniform-sized spherical bubbles form and detach from the gas injection hole in mode I for a low liquid speed and small gas flow rate. Modes III and IV occur for high-velocity liquid flows, where the injected gas elongates down along the wall and breaks up into uneven-sized bubbles. An analytical two-stage model is developed to predict the average bubble size, based on realistic force balances, and shows good agreement with measurements. Preliminary results of numerical simulations of bubble formation using a volume-of-fluid (VOF) model qualitatively match experimental observations, but more work is needed to reach a quantitative match. The analytical model is then used to estimate the size of the argon bubbles expected in liquid steel in tundish nozzles for conditions typical of continuous casting with a slide gate. The average argon bubble sizes generated in liquid steel are predicted to be larger than air bubbles in water for the same flow conditions. However, the differences lessen with increasing liquid velocity.

  11. Absorption Kinetics of Phage Lambda on Its Host Under Shear Flow

    NASA Astrophysics Data System (ADS)

    Yip, C. W.; Wu, X. L.

    2000-03-01

    Classical blender experiment by Hershey and Chase played a seminal role in illustrating the infectious process of bacteriophage to its host, and showed unequivocally that DNA is responsible for the transmission of heredity. Subsequent works by others have established that interaction between phage particles and bacterial cells is a diffusion-limited process in that, statistically speaking, each collision results in an irreversible infection. However, such a result is hard to reconcile with the fact that the infection appears to be independent of the density of phage receptors on the bacterial cell membrane. Thus, quantitative experiments showing how a phage finds its receptor and how long does it take would be valuable to this paradoxical view. Simple calculations based on Brownian motion of the phage particles show that the interaction time between the receptor and the phage is given by tau=b^2/(5D), where b is the length of the phage and D is its diffusion coefficient. Using a shear flow apparatus we study absorption kinetics of lambda phage on E. Coli (strain YMEL) under different flow conditions, and the results are compared with a simple diffusion model taking into account the hydrodynamic convection and the interaction time tau.

  12. Preparation of Few-Layer Bismuth Selenide by Liquid-Phase-Exfoliation and Its Optical Absorption Properties

    PubMed Central

    Sun, Liping; Lin, Zhiqin; Peng, Jian; Weng, Jian; Huang, Yizhong; Luo, Zhengqian

    2014-01-01

    Bismuth selenide (Bi2Se3), a new topological insulator, has attracted much attention in recent years owing to its relatively simple band structure and large bulk band gap. Compared to bulk, few-layer Bi2Se3 is recently considered as a highly promising material. Here, we use a liquid-phase exfoliation method to prepare few-layer Bi2Se3 in N-methyl-2-pyrrolidone or chitosan acetic solution. The resulted few-layer Bi2Se3 dispersion demonstrates an interesting absorption in the visible light region, which is different from bulk Bi2Se3 without any absorption in this region. The absorption spectrum of few-layer Bi2Se3 depends on its size and layer number. At the same time, the nonlinear and saturable absorption of few-layer Bi2Se3 thin film in near infrared is also characterized well and further exploited to generate laser pulses by a passive Q-switching technique. Stable Q-switched operation is achieved with a lower pump threshold of 9.3 mW at 974 nm, pulse energy of 39.8 nJ and a wide range of pulse-repetition-rate from 6.2 to 40.1 kHz. Therefore, the few-layer Bi2Se3 may excite a potential applications in laser photonics and optoelectronic devices. PMID:24762534

  13. Absorption ability and kinetics of a liquid electrolyte in PVDF-HFP copolymer containing or not SiO 2

    NASA Astrophysics Data System (ADS)

    Caillon-Caravanier, M.; Claude-Montigny, B.; Lemordant, D.; Bosser, G.

    Gel polymer electrolytes have been prepared from PVDF-HFP copolymer with various silica contents incorporating Gamma valerolactone (VL) or VL/EC (80/20 in mole) (EC: ethylene carbonate) solutions of lithium bis(trifluoromethane sulfone) imide (LiTFSI). The influence of temperature, salt content and silica addition on the kinetics of absorption and wettability of the copolymer has been investigated. An empirical model, taking into account gel swelling during the absorption allows us to relate, at constant temperature, the wetting time and the volumetric fraction of trapped electrolyte, which is a critical factor for ionic conductivity of the gel. Increasing the silica content in the dry copolymer increases the porosity and consequently the rate of absorption and thus the amount of incorporated liquid phase at saturation. To a lower extent, an increase in the temperature of absorption has the same effects. The prepared gels have good mechanicals properties and conductivities. As an example, a gel of composition: PVDF- HFP/ SiO2/ VL/ EC/ LiTFSI of molar percentages 36/6.7/42/10.5/4.8 exhibits a conductivity of 2.9 mS cm - 1 at 293 K.

  14. Recent developments of analysis for hydrodynamic flow of nematic liquid crystals

    PubMed Central

    Lin, Fanghua; Wang, Changyou

    2014-01-01

    The study of hydrodynamics of liquid crystals leads to many fascinating mathematical problems, which has prompted various interesting works recently. This article reviews the static Oseen–Frank theory and surveys some recent progress on the existence, regularity, uniqueness and large time asymptotic of the hydrodynamic flow of nematic liquid crystals. We will also propose a few interesting questions for future investigations. PMID:25332384

  15. One-step displacement dispersive liquid-liquid microextraction coupled with graphite furnace atomic absorption spectrometry for the selective determination of methylmercury in environmental samples.

    PubMed

    Liang, Pei; Kang, Caiyan; Mo, Yajun

    2016-03-01

    A novel method for the selective determination of methylmercury (MeHg) was developed by one-step displacement dispersive liquid-liquid microextraction (D-DLLME) coupled with graphite furnace atomic absorption spectrometry. In the proposed method, Cu(II) reacted with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which was used as the chelating agent instead of DDTC for the dispersive liquid-liquid microextraction (DLLME) of MeHg. Because the stability of MeHg-DDTC is higher than that of Cu-DDTC, MeHg can displace Cu from the Cu-DDTC complex and be preconcentrated in a single DLLME procedure. MeHg could be extracted into the extraction solvent phase at pH 6 while Hg(II) remained in the sample solution. Potential interference from co-existing metal ions with lower DDTC complex stability was largely eliminated without the need of any masking reagent. Under the optimal conditions, the limit of detection of this method was 13.6ngL(-1) (as Hg), and an enhancement factor of 81 was achieved with a sample volume of 5.0mL. The proposed method was successfully applied for the determination of trace MeHg in some environmental samples with satisfactory results. PMID:26717807

  16. Room temperature ionic liquids enhanced the speciation of Cr(VI) and Cr(III) by hollow fiber liquid phase microextraction combined with flame atomic absorption spectrometry.

    PubMed

    Zeng, Chujie; Lin, Yao; Zhou, Neng; Zheng, Jiaoting; Zhang, Wei

    2012-10-30

    A new method for the speciation of Cr(VI) and Cr(III) based on enhancement effect of room temperature ionic liquids (RTILs) for hollow fiber liquid phase microextraction (HF-LPME) combined with flame atomic absorption spectrometry (FAAS) was developed. Room temperature ionic liquids (RTILs) and diethyldithiocarbamate (DDTC) were used enhancement reagents and chelating reagent, respectively. The addition of room temperature ionic liquids led to 3.5 times improvement in the determination of Cr(VI). In this method, Cr(VI) reacts with DDTC yielding a hydrophobic complex, which is subsequently extracted into the lumen of hollow fiber, whereas Cr(III) is remained in aqueous solutions. The extraction organic phase was injected into FAAS for the determination of Cr(VI). Total Cr concentration was determined after oxidizing Cr(III) to Cr(VI) in the presence of KMnO(4) and using the extraction procedure mentioned above. Cr(III) was calculated by subtracting of Cr(VI) from the total Cr. Under optimized conditions, a detection limit of 0.7 ng mL(-1) and an enrichment factor of 175 were achieved. The relative standard deviation (RSD) was 4.9% for Cr(VI) (40 ng mL(-1), n=5). The proposed method was successfully applied to the speciation of chromium in natural water samples with satisfactory results. PMID:22981284

  17. Determining CDOM Absorption Spectra in Diverse Coastal Environments Using a Multiple Pathlength, Liquid Core Waveguide System. Measuring the Absorption of CDOM in the Field Using a Multiple Pathlength Liquid Waveguide System

    NASA Technical Reports Server (NTRS)

    Miller, Richard L.; Belz, Mathias; DelCastillo, Carlos; Trzaska, Rick

    2000-01-01

    We evaluated the accuracy, sensitivity and precision of a multiple pathlength, liquid core waveguide (MPLCW) system for measuring colored dissolved organic matter (CDOM) absorption in the UV-visible spectral range (370-700 nm). The MPLCW has four optical paths (2.0, 9.8, 49.3, and 204 cm) coupled to a single Teflon AF sample cell. Water samples were obtained from inland, coastal and ocean waters ranging in salinity from 0 to 36 PSU. Reference solutions for the MPLCW were made having a refractive index of the sample. CDOM absorption coefficients, a(sub CDOM), and the slope of the log-linearized absorption spectra, S, were compared with values obtained using a dual-beam spectrophotometer. Absorption of phenol red secondary standards measured by the MPLCW at 558 nm were highly correlated with spectrophotometer values (r > 0.99) and showed a linear response across all four pathlengths. Values of a(sub CDOM) measured using the MPLCW were virtually identical to spectrophotometer values over a wide range of concentrations. The dynamic range of a(sub CDOM) for MPLCW measurements was 0.002 - 231.5/m. At low CDOM concentrations (a(sub 370) < 0.1/m) spectrophotometric a(sub CDOM) were slightly greater than MPLCW values and showed larger fluctuations at longer wavelengths due to limitations in instrument precision. In contrast, MPLCW spectra followed an exponential to 600 nm for all samples. The maximum deviation in replicate MPLCW spectra was less than 0.001 absorbance units. The portability, sampling, and optical characteristics of a MPLCW system provide significant enhancements for routine CDOM absorption measurements in a broad range of natural waters.

  18. Steady flow and evaporation of a volatile liquid in a wedge

    NASA Astrophysics Data System (ADS)

    Markos, Mulugeta; Ajaev, Vladimir S.; Homsy, G. M.

    2006-09-01

    We develop a lubrication-type model of a liquid flow in a wedge in the limit of small capillary numbers and negligible gravity. Liquid flows under the action of capillary pressure gradients and thermocapillary stresses, and evaporates due to heating from the solid walls on which a constant axial temperature gradient is imposed. Steady vapor-liquid interface shapes are found for different wedge angles and material properties of the liquid. In the limit of weak evaporation (e.g., in the adiabatic region of a heat pipe) and negligible Marangoni number, the flow rate is the same in all cross sections and can be controlled by changing the wedge angle. We find the wedge angle that results in the maximum value of the flow rate for a given contact angle. For finite evaporation rates, both the flow rate and the amount of liquid in each cross section along the wedge decrease until the point of dry-out is reached. The location of the dry-out point is studied as a function of evaporation conditions. Somewhat counterintuitively, we find that the dry-out point shifts toward the region of higher temperature as evaporation intensity is increased. The effect of thermocapillary stresses on the vapor-liquid interface shape is also investigated in the limit of negligible evaporation. Since thermocapillarity generally opposes the capillary flow, it leads to shorter wetted lengths. The implications of the results for design and optimization of micro heat pipes are discussed.

  19. Electronic absorption spectra of imidazolium-based ionic liquids studied by far-ultraviolet spectroscopy and quantum chemical calculations.

    PubMed

    Tanabe, Ichiro; Kurawaki, Yuji; Morisawa, Yusuke; Ozaki, Yukihiro

    2016-08-10

    Electronic absorption spectra of imidazolium-based ionic liquids were studied by far- and deep-ultraviolet spectroscopy and quantum chemical calculations. The absorption spectra in the 145-300 nm region of imidazolium-based ionic liquids, [Cnmim](+)[BF4](-) (n = 2, 4, 8) and [C4mim](+)[PF6](-), were recorded using our original attenuated total reflectance (ATR) system spectrometer. The obtained spectra had two definitive peaks at ∼160 and ∼210 nm. Depending on the number of carbon atoms in the alkyl side chain, the peak wavelength around 160 nm changed, while that around 210 nm remained at almost the same wavelength. Quantum chemical calculation results based on the time-dependent density functional theory (TD-DFT) also showed the corresponding peak shifts. In contrast, there was almost no significant difference between [C4mim](+)[BF4](-) and [C4mim](+)[PF6](-), which corresponded with our calculations. Therefore, it can be concluded that the absorption spectra in the 145-300 nm region are mainly determined by the cations when fluorine-containing anions are adopted. In addition, upon addition of organic solvent (acetonitrile) to [C4mim](+)[BF4](-), small peak shifts to the longer wavelength were revealed for both peaks at ∼160 and ∼210 nm. The peak shift in the deep-ultraviolet region (≤200 nm) in the presence of the solvent, which indicates the change of electronic states of the ionic liquid, was experimentally observed for the first time by using the ATR spectrometer. PMID:27471106

  20. High sensitivity liquid phase measurements using broadband cavity enhanced absorption spectroscopy (BBCEAS) featuring a low cost webcam based prism spectrometer.

    PubMed

    Qu, Zhechao; Engstrom, Julia; Wong, Donald; Islam, Meez; Kaminski, Clemens F

    2013-11-01

    Cavity enhanced techniques enable high sensitivity absorption measurements in the liquid phase but are typically more complex, and much more expensive, to perform than conventional absorption methods. The latter attributes have so far prevented a wide spread use of these methods in the analytical sciences. In this study we demonstrate a novel BBCEAS instrument that is sensitive, yet simple and economical to set up and operate. We use a prism spectrometer with a low cost webcam as the detector in conjunction with an optical cavity consisting of two R = 0.99 dielectric mirrors and a white light LED source for illumination. High sensitivity liquid phase measurements were made on samples contained in 1 cm quartz cuvettes placed at normal incidence to the light beam in the optical cavity. The cavity enhancement factor (CEF) with water as the solvent was determined directly by phase shift cavity ring down spectroscopy (PS-CRDS) and also by calibration with Rhodamine 6G solutions. Both methods yielded closely matching CEF values of ~60. The minimum detectable change in absorption (αmin) was determined to be 6.5 × 10(-5) cm(-1) at 527 nm and was limited only by the 8 bit resolution of the particular webcam detector used, thus offering scope for further improvement. The instrument was used to make representative measurements on dye solutions and in the determination of nitrite concentrations in a variation of the widely used Griess Assay. Limits of detection (LOD) were ~850 pM for Rhodamine 6G and 3.7 nM for nitrite, respectively. The sensitivity of the instrument compares favourably with previous cavity based liquid phase studies whilst being achieved at a small fraction of the cost hitherto reported, thus opening the door to widespread use in the community. Further means of improving sensitivity are discussed in the paper. PMID:24049768

  1. Dispersiveness of Liquid Droplets Sprayed with Cocurrent Gas Flow

    NASA Astrophysics Data System (ADS)

    Arkhipov, Vladimir; Antonnikova, Alexandra; Basalayev, Sergey; Zharova, Irina; Orlov, Sergey

    2016-02-01

    Pneumohydraulic stand, equipped with a set of aerosol systems laser diagnostics devices, are presented. The results of experimental measurements of the aerosol liquid-drop size distribution in the ejection nozzle spray pattern are provided.

  2. Direct numerical simulation of interfacial wave generation in turbulent gas-liquid flows in horizontal channels

    NASA Astrophysics Data System (ADS)

    Campbell, Bryce; Hendrickson, Kelli; Liu, Yuming; Subramani, Hariprasad

    2014-11-01

    For gas-liquid flows through pipes and channels, a flow regime (referred to as slug flow) may occur when waves form at the interface of a stratified flow and grow until they bridge the pipe diameter trapping large elongated gas bubbles within the liquid. Slug formation is often accompanied by strong nonlinear wave-wave interactions, wave breaking, and gas entrainment. This work numerically investigates the fully nonlinear interfacial evolution of a two-phase density/viscosity stratified flow through a horizontal channel. A Navier-Stokes flow solver coupled with a conservative volume-of-fluid algorithm is use to carry out high resolution three-dimensional simulations of a turbulent gas flowing over laminar (or turbulent) liquid layers. The analysis of such flows over a range of gas and liquid Reynolds numbers permits the characterization of the interfacial stresses and turbulent flow statistics allowing for the development of physics-based models that approximate the coupled interfacial-turbulent interactions and supplement the heuristic models built into existing industrial slug simulators.

  3. Two-Dimensional Numerical Simulation of Boiling Two-Phase Flow of Liquid Nitrogen

    NASA Astrophysics Data System (ADS)

    Ishimoto, Jun; Oike, Mamoru; Kamijo, Kenjiro

    Two-dimensional characteristics of the boiling two-phase flow of liquid nitrogen in a duct flow are numerically investigated to contribute to the further development of new high-performance cryogenic engineering applications. First, the governing equations of the boiling two-phase flow of liquid nitrogen based on the unsteady drift-flux model are presented and several flow characteristics are numerically calculated taking account the effect of cryogenic flow states. Based on the numerical results, a two-dimensional structure of the boiling two-phase flow of liquid nitrogen is shown in detail, and it is found that the phase change of liquid nitrogen occurs in quite a short time interval compared with that of two-phase pressurized water at high temperature. Next, it is clarified that the distributions of pressure and the void fraction in a two-phase flow show a tendency different from those of fluids at room temperature because of the decrease in sound velocity due to large compressibility and the rapid phase change velocity in a cryogenic two-phase mixture flow. According to these numerical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained will contribute to advanced cryogenic industrial applications.

  4. Numerical investigation for the effect of the liquid film volume on thermocapillary flow direction in a thin circular liquid film

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Takagi, Y.; Okano, Y.; Dost, S.

    2013-08-01

    NASA Astronaut Dr. Pettit carried out a thermocapillary flow experiment onboard the International Space Station in 2003. In this experiment a thin water film containing milk powder was formed in a stainless-steel wire ring. Heating a section of the ring by a soldering iron induced in the water film a thermocapillary flow towards the heated section of the ring (outward flow: cold to hot). This flow was in the opposite direction of the usually observed thermocapillary flows (inward flow: hot to cold). To shed light on this interesting phenomenon observed in the space experiment, we have conducted a three-dimensional numerical simulation study. Simulation results showed that the film geometry of the water film is a key factor determining flow direction and flow strength. When the liquid film free surfaces are convex, i.e., the water film volume is larger than that when the free surfaces are flat, an outward flow develops in the film as observed in the space experiment. However, when the free surfaces are concave, the simulation predicts an inward flow.

  5. Automatic liquid crystal thermography for transient heat transfer measurements in hypersonic flow

    NASA Astrophysics Data System (ADS)

    Babinsky, H.; Edwards, J. A.

    1996-08-01

    A technique has been developed to measure surface heat transfer on windtunnel models in hypersonic flow based on the colour response of encapsulated thermochromic liquid crystals. The method supplies results of a superior spatial resolution at experimental uncertainties comparable to traditional methods. The approach is different from other liquid crystal applications in several key areas. It combines the calibration of the liquid crystal coating with the actual mesurement and therefore allows for an efficient experiment. The method is automated in most steps involved. Results are shown for the flow over an axisymmetric compression corner at Mach 5 and compared with surface thermocouple measurements.

  6. Liquid crystals under the spotlight: light based measurements of electrical and flow properties of liquid crystals

    NASA Astrophysics Data System (ADS)

    Bennett, Thomas P.; Proctor, Matthew B.; Kaczmarek, Malgosia; D'Alessandro, Giampaolo

    2015-09-01

    Optical light modulation in photorefractive liquid crystal cells depends strongly on the relative voltage drop across the photoconductive and liquid crystal layers. This quantity can be estimated using the Voltage Transfer Function, a generalization of the standard cross polarized intensity measurements. Another advantage of this new measurement technique is that we can use it to estimate dynamical parameters of the liquid crystal and of the device, either through simple black-box models or using a full Ericksen-Leslie theory. In this latter case we can obtain estimates of some of the viscosities of the liquid crystal.

  7. Deep ultraviolet Raman spectroscopy: A resonance-absorption trade-off illustrated by diluted liquid benzene

    NASA Astrophysics Data System (ADS)

    Chadwick, C. T.; Willitsford, A. H.; Philbrick, C. R.; Hallen, H. D.

    2015-12-01

    The magnitude of resonance Raman intensity, in terms of the real signal level measured on-resonance compared to the signal level measured off-resonance for the same sample, is investigated using a tunable laser source. Resonance Raman enhancements, occurring as the excitation energy is tuned through ultraviolet absorption lines, are used to examine the 1332 cm-1 vibrational mode of diamond and the 992 cm-1 ring-breathing mode of benzene. Competition between the wavelength dependent optical absorption and the magnitude of the resonance enhancement is studied using measured signal levels as a function of wavelength. Two system applications are identified where the resonance Raman significantly increases the real signal levels despite the presence of strong absorption: characterization of trace species in laser remote sensing and spectroscopy of the few molecules in the tiny working volumes of near-field optical microscopy.

  8. Operating experience using venturi flow meters at liquid helium temperature

    SciTech Connect

    Wu, K.C.

    1992-06-01

    Experiences using commercial venturi to measure single phase helium flow near 4 K (degree Kelvin) for cooling superconducting magnets have been presented. The mass flow rate was calculated from the differential pressure and the helium density evaluated from measured pressure and temperature. The venturi flow meter, with a full range of 290 g/s (0.29 Kg/s) at design conditions, has been found to be reliable and accurate. The flow measurements have been used, with great success, for evaluating the performance of a cold centrifugal compressor, the thermal acoustic heat load of a cryogenic system and the cooling of a superconducting magnet after quench.

  9. Operating experience using venturi flow meters at liquid helium temperature

    SciTech Connect

    Wu, K.C.

    1992-01-01

    Experiences using commercial venturi to measure single phase helium flow near 4 K (degree Kelvin) for cooling superconducting magnets have been presented. The mass flow rate was calculated from the differential pressure and the helium density evaluated from measured pressure and temperature. The venturi flow meter, with a full range of 290 g/s (0.29 Kg/s) at design conditions, has been found to be reliable and accurate. The flow measurements have been used, with great success, for evaluating the performance of a cold centrifugal compressor, the thermal acoustic heat load of a cryogenic system and the cooling of a superconducting magnet after quench.

  10. Characteristics of flow, mixing and chemical reaction of two liquids in a thin gap

    NASA Astrophysics Data System (ADS)

    Nagatsu, Yuichiro; Ueda, Toshihisa

    1999-11-01

    Characteristics of flow, mixing and chemical reaction of two liquids in a thin gap (less than 1mm) are examined experimentally. The flow in a thin gap is formed in a Hele-Shaw cell, consisting of two parallel closely spaced glass plates. A less viscous liquid is injected at a constant volumetric flow rate into the cell that is filled with a more viscous liquid. Experiments are done varying the viscosities of liquids, the concentrations of reactants, the injection flow rate and the gap of the cell respectively. The viscosities of viscous liquids are varied by weight concentrations of water and glycerin. As reactants, Ferric Nitrate(‡V)(Fe(NO3)) is used for the more viscous liquid and Potassium Thiocyanate(KSCN) for the less one. (Chemical reaction used in this study is as follows ; Fe3+(yellow)+KSCN(colorless)\\x81¨[FeSCN]2+(bloody red) ) Regions of reactants and product are identified by the difference of the colors of reactants and product. The images of the patterns of flow, mixing and chemical reaction photographed by a video camera are analyzed. The region of product changes remarkably as the gap of the cell is decreased. Additional experimental results will be presented at the meeting.

  11. Enhanced critical heat flux by capillary driven liquid flow on the well-designed surface

    NASA Astrophysics Data System (ADS)

    Kim, Dong Eok; Park, Su Cheong; Yu, Dong In; Kim, Moo Hwan; Ahn, Ho Seon

    2015-07-01

    Based on the unique design of the surface morphology, we investigated the effects of gravity and capillary pressure on Critical heat flux (CHF). The micro-structured surfaces for pool boiling tests were comprised with both the rectangular cavity and microchannel structures. The microcavity structures could intrinsically block the liquid flow by capillary pressure effect, and the capillary flow into the boiling surface was one-dimensionally induced only through the microchannel region. Thus, we could clearly establish the relationship between the CHF and capillary wicking flow. The driving potentials for the liquid inflow can be classified into the hydrostatic head by gravitational force, and the capillary pressure induced by the interactions of vapor bubbles, liquid film, and surface solid structures. Through the analysis of the experimental data and visualization of vapor bubble behaviors, we present that the liquid supplement to maintain the nucleate boiling regime in pool boiling condition is governed by the gravitational pressure head and capillary pressure effect.

  12. Method of driving liquid flow at or near the free surface using magnetic microparticles

    DOEpatents

    Snezhko, Oleksiy; Aronson, Igor; Kwok, Wai-Kwong; Belkin, Maxim V.

    2011-10-11

    The present invention provides a method of driving liquid flow at or near a free surface using self-assembled structures composed of magnetic particles subjected to an external AC magnetic field. A plurality of magnetic particles are supported at or near a free surface of liquid by surface tension or buoyancy force. An AC magnetic field traverses the free surface and dipole-dipole interaction between particles produces in self-assembled snake structures which oscillate at the frequency of the traverse AC magnetic field. The snake structures independently move across the free surface and may merge with other snake structures or break up and coalesce into additional snake structures experiencing independent movement across the liquid surface. During this process, the snake structures produce asymmetric flow vortices across substantially the entirety of the free surface, effectuating liquid flow across the free surface.

  13. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  14. Rapid flow fractionation of particles combining liquid and particulate dielectrophoresis

    NASA Technical Reports Server (NTRS)

    King, Michael R. (Inventor); Lomakin, Oleg (Inventor); Jones, Thomas B. (Inventor); Ahmed, Rajib (Inventor)

    2007-01-01

    Rapid, size-based, deposition of particles from liquid suspension is accomplished using a nonuniform electric field created by coplanar microelectrode strips patterned on an insulating substrate. The scheme uses the dielectrophoretic force both to distribute aqueous liquid containing particles and, simultaneously, to separate the particles. Size-based separation is found within nanoliter droplets formed along the structure after voltage removal. Bioparticles or macromolecules of similar size can also be separated based on subtle differences in dielectric property, by controlling the frequency of the AC current supplied to the electrodes.

  15. Miniature liquid flow sensor and feedback control of electroosmotic and pneumatic flows for a micro gas analysis system.

    PubMed

    Ohira, Shin-Ichi; Toda, Kei

    2006-01-01

    Accurate liquid flow control is important in most chemical analyses. In this work, the measurement of liquid flow in microliters per minute was performed, and feedback control of the flow rate was examined. The flow sensor was arranged on a channel made in a polydimethylsiloxane (PDMS) block. The center of the channel was cooled by a miniature Peltier device, and the change in temperature balance along the channel formed by the flow was measured by two temperature sensors. Using this flow sensor, feedback flow control was examined with two pumping methods. One was the electroosmotic flow method, made by applying a high voltage (HV) between the reagent and waste reservoirs; the other was the piezo valve method, in which a micro-valve-seat was fabricated in a PDMS cavity with a silicone diaphragm. The latter was adopted for a micro gas analysis system (microGAS) for measuring atmospheric H2S and SO2. The obtained baselines were stable, and better limits of detection were obtained. PMID:16429774

  16. Numerical simulation of cavitating flow of liquid helium in a pipe using multi-fluid model

    NASA Astrophysics Data System (ADS)

    Ishimoto, J.; Oike, M.; Kamijo, K.

    2002-05-01

    The two-dimensional characteristics of the cavitating flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the turbulent cavitating flow of liquid helium passing through the orifice is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic cavitating flow are predicted.

  17. The effects of bubbles on the structure of upward gas-liquid flow

    NASA Astrophysics Data System (ADS)

    Gubaidulin, D. A.; Snigerev, B. A.

    2016-01-01

    The paper presents the results of study of the local structure of turbulent gas-liquid flow in vertical pipe. A mathematical model based on the use of Eulerian description for both phases taking into account the action of different forces of interfacial interaction. Special attention is paid to the development of approaches for the simulation of polydispersed bubbly flows taking into account processes of coagulation and fragmentation. Comparison of simulation results with experimental data showed that the developed approach allows to obtain detailed information about the structures of turbulent gas-liquid flows, the distribution of bubbles by size.

  18. Flow-driven transition and associated velocity profiles in a nematic liquid-crystal cell.

    PubMed

    Jewell, S A; Cornford, S L; Yang, F; Cann, P S; Sambles, J R

    2009-10-01

    The alignment properties and distribution of flow speed during Poiseuille flow through a microchannel of a nematic liquid crystal in a cell with homeotropic surface alignment has been measured using a combination of conoscopy, fluorescence confocal polarizing microscopy, and time-lapse imaging. Two topologically distinct director profiles, with associated fluid velocity fields, are found to exist with the preferred state dictated by the volumetric flow rate of the liquid crystal. The results show excellent agreement with model data produced using the Ericksen-Leslie nematodynamics theory. PMID:19905324

  19. Convective heat and mass transfer during the evaporation of a liquid into a gas flow

    NASA Astrophysics Data System (ADS)

    Boiarshinov, B. F.; Volchkov, E. P.; Terekhov, V. I.

    1985-10-01

    Heat and mass transfer processes associated with liquid evaporation are analyzed for adiabatic and nonadiabatic conditions. Experimental data are then presented on heat and mass transfer during the evaporation of water and ethyl alcohol from a porous surface. It is shown that heat and mass transfer under conditions of evaporation can be described by using expressions for flow past a 'dry' wall. A diagram is presented for determining the magnitudes of additional heat sources in the case of nonadiabatic evaporation. Finally, the effect of various factors, such as temperature, flow humidity, and liquid type, on heat and mass transfer during evaporation is analyzed for laminar and turbulent flows.

  20. Pumping of dielectric liquids using non-uniform-field induced electrohydrodynamic flow

    NASA Astrophysics Data System (ADS)

    Kim, Wonkyoung; Chun Ryu, Jae; Kweon Suh, Yong; Hyoung Kang, Kwan

    2011-11-01

    We present a method of pumping dielectric (or non-polar) liquids. The pumping method relies on the electrohydrodynamic flow generated by field dependent electrical conductivity (Onsager effect). Adding a small amount of polar liquid increases the field-dependency of conductivity. Applying either dc or ac voltage produces a fast and regular flow around electrodes. Flow speed is proportional to cube of electric-field strength and inversely to applied frequency. The experimental results agreed well with numerical analysis based on our theoretical model.

  1. Performance analysis on solid-liquid mixed flow in a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Ning, C.; Wang, Y.

    2016-05-01

    In order to study the solid-liquid mixed flow hydraulic characteristics of centrifugal pump, the Pro/E software was used for three-dimensional modeling of centrifugal pump chamber. By using the computational fluid dynamics software CFX, the numerical simulation calculation of solid-liquid two-phase flow within whole flow passage of centrifugal pump was conducted. Aim at different particle diameters, the Reynolds-averaged N-S equations with the RNG k-Ɛ turbulence model and SIMPLEC algorithm were used to simulate the two-phase flow respectively on the condition of different volume fraction. The influence of internal flow characteristic on pump performance was analyzed. On the conditions of different particle diameter and different volume fraction, the turbulence kinetic energy and particle concentration are analyzed. It can be found that the erosion velocity ratio on the flow channel wall increases along with the increasing of the volume fraction

  2. Shear Flow Induced Transition from Liquid-Crystalline to Polymer Behavior in Side-Chain Liquid Crystal Polymers

    NASA Astrophysics Data System (ADS)

    Noirez, L.; Lapp, A.

    1997-01-01

    We determine the structure and conformation of side-chain liquid-crystalline polymers subjected to shear flow in the vicinity of the smectic phase by neutron scattering on the velocity gradient plane. Below the nematic-smectic transition we observe a typical liquid-crystal behavior; the smectic layers slide, leading to a main-chain elongation parallel to the velocity direction. In contrast, a shear applied above the transition induces a tilted main-chain conformation which is typical for polymer behavior.

  3. Determination of calcium, magnesium and strontium in soils by flow injection flame atomic absorption spectrometry.

    PubMed

    Arslan, Z; Tyson, J F

    1999-12-01

    Several procedures for the determination of Ca, Mg and Sr in soils have been compared on the basis of the accuracy of analysis of two NIST reference materials (Montana Soils SRM 2710 and SRM 2711). Samples were dissolved in a mixture of hydrofluoric and nitric acids in sealed vessels in a microwave oven and in teflon beakers on a hot plate. The digests obtained from both dissolution methods were evaporated to dryness in an attempt to remove silicon. Boric acid was added to prevent the precipitation of the lanthanum releasing agent (as lanthanum fluoride) and potassium was added as an ionization buffer. Determinations were made by flame atomic absorption spectrometry with both the nitrous oxide-acetylene flame and the air-acetylene flame, with calibration either by standard additions or against external standards matrix matched with respect to nitric acid, boric acid, lanthanum and potassium. The silicon remaining in the solution was also determined by external calibration. A single-line flow injection manifold was used to overcome any problems due to the presence of high dissolved solids. A volume of 300 mul was injected into a water carrier stream flowing at 8 ml min(-1). To determine Ca in the air-acetylene flame, it was necessary to remove silicon. Magnesium was determined in either flame without complete removal of the silicon, however, for the determination of Sr, it was necessary to remove the silicon and use the nitrous oxide-acetylene flame. The indicative value for Sr in SRM 2710 was too low: the value determined was 360+/-30 mug g(-1). PMID:18967785

  4. The effect of surfactant on stratified and stratifying gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Heiles, Baptiste; Zadrazil, Ivan; Matar, Omar

    2013-11-01

    We consider the dynamics of a stratified/stratifying gas-liquid flow in horizontal tubes. This flow regime is characterised by the thin liquid films that drain under gravity along the pipe interior, forming a pool at the bottom of the tube, and the formation of large-amplitude waves at the gas-liquid interface. This regime is also accompanied by the detachment of droplets from the interface and their entrainment into the gas phase. We carry out an experimental study involving axial- and radial-view photography of the flow, in the presence and absence of surfactant. We show that the effect of surfactant is to reduce significantly the average diameter of the entrained droplets, through a tip-streaming mechanism. We also highlight the influence of surfactant on the characteristics of the interfacial waves, and the pressure gradient that drives the flow. EPSRC Programme Grant EP/K003976/1.

  5. Time and flow-direction responses of shear-styress-sensitive liquid crystal coatings

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.; Muraqtore, J. J.; Heinick, James T.

    1994-01-01

    Time and flow-direction responses of shear-stress liquid crystal coatings were exploresd experimentally. For the time-response experiments, coatings were exposed to transient, compressible flows created during the startup and off-design operation of an injector-driven supersonic wind tunnel. Flow transients were visualized with a focusing schlieren system and recorded with a 100 frame/s color video camera.

  6. Reduced Gravity Gas and Liquid Flows: Simple Data for Complex Problems

    NASA Technical Reports Server (NTRS)

    McQuillen, John; Motil, Brian

    2001-01-01

    While there have been many studies for two-phase flow through straight cylindrical tubes, more recently, a new group of studies have emerged that examine two-phase flow through non-straight, non-cylindrical geometries, including expansions, contractions, tees, packed beds and cyclonic separation devices. Although these studies are still, relatively speaking, in their infancy, they have provided valuable information regarding the importance of the flow momentum, and the existence of liquid dryout due to sharp comers in microgravity.

  7. Note: Ultrasonic liquid flow meter for small pipes.

    PubMed

    Yu, Yang; Zong, Guanghua

    2012-02-01

    An ultrasonic flow meter for small pipes is presented. For metal pipe diameter smaller than 10 mm, clamp-on ultrasonic contrapropagation flow meters may encounter difficulties if cross talk or the short acoustic path contributes to large uncertainty in transit time measurement. Axial inline flow meters can avoid these problems, but they may introduce other problems if the transducer port is not properly positioned. Three types of pipe connecting tees are compared using the computational fluid dynamics (CFD) method. CFD shows the 45° tee has more uniform velocity distribution over the measuring section. A prototype flow meter using the 45° tee was designed and tested. The zero flow experiment shows the flow meter has a maximum of 0.002 m∕s shift over 24 h. The flow meter is calibrated by only 1 meter factor. After calibration, inaccuracy lower than 0.1% of reading was achieved in the laboratory, for a measuring range from 15 to 150 g∕s (0.29 to 2.99 m∕s; Re = 2688 to 26,876). PMID:22380141

  8. Note: Ultrasonic liquid flow meter for small pipes

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Zong, Guanghua

    2012-02-01

    An ultrasonic flow meter for small pipes is presented. For metal pipe diameter smaller than 10 mm, clamp-on ultrasonic contrapropagation flow meters may encounter difficulties if cross talk or the short acoustic path contributes to large uncertainty in transit time measurement. Axial inline flow meters can avoid these problems, but they may introduce other problems if the transducer port is not properly positioned. Three types of pipe connecting tees are compared using the computational fluid dynamics (CFD) method. CFD shows the 45° tee has more uniform velocity distribution over the measuring section. A prototype flow meter using the 45° tee was designed and tested. The zero flow experiment shows the flow meter has a maximum of 0.002 m/s shift over 24 h. The flow meter is calibrated by only 1 meter factor. After calibration, inaccuracy lower than 0.1% of reading was achieved in the laboratory, for a measuring range from 15 to 150 g/s (0.29 to 2.99 m/s; Re = 2688 to 26 876).

  9. Numerical modeling of gas-liquid flows in mini- and microchannels

    NASA Astrophysics Data System (ADS)

    Guzei, D. V.; Minakov, A. V.; Pryazhnikov, M. I.; Dekterev, A. A.

    2015-01-01

    The paper presents the results of testing a methodology for calculating two-phase flows in mini- and microchannels. The numerical methodology is based on the known fluid-in-cell method (VOF method) and the CSF procedure to account for surface tension forces. Solutions of several test problems of two-phase flow in microchannels, including the water-oil emulsion flow and gas-liquid flow in microchannels of the T-type and the stationary slug flow in a circular minichannel, were considered with the aid of this technique. Comparisons of numerical results with experimental data were carried out. A good agreement between the results was obtained.

  10. Transition from steady to periodic liquid-metal magnetohydrodynamic flow in a sliding electrical contact

    NASA Astrophysics Data System (ADS)

    Talmage, Gita; Walker, John S.; Brown, Samuel H.; Sondergaard, Neal A.

    1993-09-01

    In homopolar motors and generators, large dc electric currents pass through the sliding electrical contacts between rotating copper disks (rotors) and static copper surfaces shrouding the rotor tips (stators). A liquid metal in the small radial gap between the rotor tip and concentric stator surface can provide a low-resistance, low-drag electrical contact. Since there is a strong magnetic field in the region of the electrical contacts, there are large electromagnetic body forces on the liquid metal. The primary, azimuthal motion consists of simple Couette flow, plus an electromagnetically driven flow with large extremes of the azimuthal velocity near the rotor corners. The secondary flow involves the radial and axial velocity components, is driven by the centrifugal force associated with the primary flow, and is opposed by the electromagnetic body force, so that the circulation varies inversely as the square of the magnetic-field strength. Three flow regimes are identified as the angular velocity Ω of the rotor is increased. For small Ω, the primary flow is decoupled from the secondary flow. As Ω increases, the secondary flow begins to convect the azimuthal-velocity peaks radially outward, which in turn changes the centrifugal force driving the secondary flow. At some critical value of Ω, the flow becomes periodic through the coupling of the primary and secondary flows. The azimuthal-velocity peaks begin to move radially in and out with an accompanying oscillation in the secondary-flow strength.

  11. Microprocessor Based Temperature Control of Liquid Delivery with Flow Disturbances.

    ERIC Educational Resources Information Center

    Kaya, Azmi

    1982-01-01

    Discusses analytical design and experimental verification of a PID control value for a temperature controlled liquid delivery system, demonstrating that the analytical design techniques can be experimentally verified by using digital controls as a tool. Digital control instrumentation and implementation are also demonstrated and documented for…

  12. Liquid and liquid–gas flows at all speeds

    SciTech Connect

    LeMartelot, S.; Nkonga, B.; Saurel, R.

    2013-12-15

    All speed flows and in particular low Mach number flow algorithms are addressed for the numerical approximation of the Kapila et al. [1] multiphase flow model. This model is valid for fluid mixtures evolving in mechanical equilibrium but out of temperature equilibrium and is efficient for material interfaces computation separating miscible and non-miscible fluids. In this context, the interface is considered as a numerically diffused zone, captured as well as all present waves (shocks, expansion waves). The same flow model can be used to solve cavitating and boiling flows [2]. Many applications occurring with liquid–gas interfaces and cavitating flows involve a very wide range of Mach number, from 10{sup −3} to supersonic (and even hypersonic) conditions with respect to the mixture sound speed. It is thus important to address numerical methods free of restrictions regarding the Mach number. To do this, a preconditioned Riemann solver is built and embedded into the Godunov explicit scheme. It is shown that this method converges to exact solutions but needs too small time steps to be efficient. An implicit version is then derived, first in one dimension and second in the frame of 2D unstructured meshes. Two-phase flow preconditioning is then addressed in the frame of the Saurel et al. [3] algorithm. Modifications of the preconditioned Riemann solver are needed and detailed. Convergence of both single phase and two-phase numerical solutions are demonstrated with the help of single phase and two-phase steady nozzle flow solutions. Last, the method is illustrated by the computation of real cavitating flows in Venturi nozzles. Vapour pocket size and instability frequencies are reproduced by the model and method without using any adjustable parameter.

  13. Three-Dimensional Flow of an Oldroyd-B Fluid with Variable Thermal Conductivity and Heat Generation/Absorption

    PubMed Central

    Shehzad, Sabir Ali; Alsaedi, Ahmed; Hayat, Tasawar; Alhuthali, M. Shahab

    2013-01-01

    This paper looks at the series solutions of three dimensional boundary layer flow. An Oldroyd-B fluid with variable thermal conductivity is considered. The flow is induced due to stretching of a surface. Analysis has been carried out in the presence of heat generation/absorption. Homotopy analysis is implemented in developing the series solutions to the governing flow and energy equations. Graphs are presented and discussed for various parameters of interest. Comparison of present study with the existing limiting solution is shown and examined. PMID:24223780

  14. Determination of arsenic in a nickel alloy by flow injection hydride generation atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Hanna, C. P.; Tyson, J. F.; Offley, S. G.

    1992-08-01

    The development of a method for the direct determination of trace arsenic quantities in nickel alloy digests, by flow injection hydride generation atomic absorption spectrometry, is described. An optimization study of the manifold and chemical parameters produced system performance, in terms of tolerance of the nickel matrix and sensitivity, such that matrix removal and pre-reduction of As(V) to As (III) prior to arsine generation were eliminated. Full recovery of the As(V) signal from a solution containing 5 ng ml -1 in the presence of 60 μg ml -1 nickel was obtained. Validation of the method was achieved by analyzing a British Chemical Standard (BCS) Certified Reference Material (CRM) #346 IN nickel alloy containing arsenic at a concentration of 50 μg g -1. Following dissolution in nitric and hydrofluoric acids by a microwave assisted procedure, the only subsequent preparation required was dilution by the appropriate factor. Up to 60 injections h -1 may be made, with a detection limit of 0.5 ng ml -1 arsenic (250 pg absolute) as As(V) in a 500 μl sample. The peak height characteristic concentration is 0.46 ng ml -1, with a relative standard deviation of 3.5% for a 10 ng ml -1 As(V) standard ( n = 6).

  15. Heavy Metals Effect on Cyanobacteria Synechocystis aquatilis Study Using Absorption, Fluorescence, Flow Cytometry, and Photothermal Measurements

    NASA Astrophysics Data System (ADS)

    Dudkowiak, A.; Olejarz, B.; Łukasiewicz, J.; Banaszek, J.; Sikora, J.; Wiktorowicz, K.

    2011-04-01

    The toxic effect of six heavy metals on cyanobacteria Synechocystis aquatilis was studied by absorption, fluorescence, flow cytometry, and photothermal measurements. This study indicates that at the concentration used, the cyanobacteria are more sensitive to silver, copper, and mercury than to cadmium, lead, and zinc metals. Disregarding the decrease in the yields of the related radiative processes caused by photochemical processes and/or damage to phycobilisomes, no changes were detected in the efficiency of thermal deactivation processes within a few microseconds, which can indicate the lack of disturbances in the photosynthetic light reaction and the lack of damage to the photosystem caused by the heavy metal ions in the concentrations used. The results demonstrate that the relative values of fluorescence yield as well as promptly generated heat calculated for the metal-affected and unaffected (reference) bacteria are sensitive indicators of environmental pollution with heavy metal ions, whereas the complementary methods proposed could be used as a noninvasive and fast procedure for in vivo assessment of their toxicity.

  16. Fiber optic liquid mass flow sensor and method

    NASA Technical Reports Server (NTRS)

    Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)

    2010-01-01

    A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.

  17. Liquid flow and distribution in unsaturated porous media

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan

    2004-01-01

    Flow and transport in permeable or porous media and microchannels occurs in a variety of situations in micro- and reduced-gravity environments, many of them associated with environmental control and life support systems. While the role of gravity is limited, due to the typically small size scales associated permeable media, gravity, at the very least, affects the overall disposition of fluid in a macroscopic system. This presentation will discuss examples where the absence of gravity affects flow and phase distribution in selected examples of unsaturated flow and transport of heat and mass in porous media and microchannels that are pertinent to spacecraft systems.

  18. An ultrasonic flowmeter for measuring dynamic liquid flow

    NASA Technical Reports Server (NTRS)

    Carpini, T. D.; Monteith, J. H.

    1978-01-01

    A novel oscillating pipe system was developed to provide dynamic calibration wherein small sinusoidal signals with amplitudes of 0.5 to 10% of the steady-state flow were added to the steady-state flow by oscillating the flowmeter relative to the fixed pipes in the flow system. Excellent agreement was obtained between the dynamic velocities derived from an accelerometer mounted on the oscillating pipe system and those sensed by the flowmeter at frequencies of 7, 19, and 30 Hz. Also described were the signal processing techniques used to retrieve the small sinusoidal signals which were obscured by the fluid turbulence.

  19. Nanostructure of liquid crystalline matrix determines in vitro sustained release and in vivo oral absorption kinetics for hydrophilic model drugs.

    PubMed

    Lee, Kathy W Y; Nguyen, Tri-Hung; Hanley, Tracey; Boyd, Ben J

    2009-01-01

    Nanostructured lipid-based liquid crystalline systems have been proposed as sustained oral drug delivery systems, but the interplay between their intrinsic release rates, susceptibility to digestive processes, and the manner in which these effects impact on their application in vivo, are not well understood. In this study, two different bicontinuous cubic phases, prepared from glyceryl monooleate and phytantriol, and a reversed hexagonal phase formed by addition of a small amount of vitamin E to phytantriol (Q(II GMO), Q(II PHYT) and H(II PHYT+VitEA), respectively) were prepared. The release kinetics for a number of model hydrophilic drugs with increasing molecular weights (glucose, Allura Red and FITC-dextrans) was determined in in vitro release experiments. Diffusion-controlled release was observed in all cases as anticipated from previous studies with liquid crystalline systems, and it was discovered that the release rates of each drug decreased as the matrix was changed from Q(II GMO) to Q(II PHYT) to H(II PHYT+VitEA). Formulations containing (14)C-glucose, utilized as a rapidly absorbed marker of drug release, were then orally administered to rats to determine the relative in vivo absorption rates from the different formulations. The results showed a trend by which the rate of absorption of (14)C-glucose followed that observed in the corresponding in vitro release studies, providing the first indication that the nanostructure of these materials may provide the ability to tailor the absorption kinetics of hydrophilic drugs in vivo, and hence form the basis of a new drug delivery system. PMID:18790030

  20. Pressure drop in fully developed, duct flow of dispersed liquid-vapor mixture at zero gravity

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The dynamics of steady, fully developed dispersed liquid-vapor flow in a straight duct at 0-g is simulated by flowing water containing n-butyl benzoate droplets. Water and benzoate are immiscible and have identical density at room temperature. The theoretical basis of the simulation is given. Experiments showed that, for a fixed combined flow rate of water and benzoate, the frictional pressure drop is unaffected by large changes in the volume fraction of benzoate drops and their size distribution. Measured power spectra of the static wall pressure fluctuations induced by the turbulent water-benzoate flow also revealed that their dynamics is essentially unaltered by the presence of the droplets. These experimental findings, together with the theoretical analysis, led to the conclusion that the pressure drop in fully developed, dispersed liquid-vapor flow in straight ducts of constant cross section at 0-g is identical to that due to liquid flowing alone at the same total volumetric flow rate of the liquid-vapor mixture and, therefore, can be readily determined.

  1. Spatio-temporal evolution of interfacial instabilities in vertical gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Schmidt, Patrick; Valluri, Prashant; Ó Náraigh, Lennon; Lucquiaud, Mathieu

    2014-11-01

    Vertical gas-liquid flows are characteristic for process engineering and widely employed in various technical applications. However, the dynamic behaviour of the liquid interface in such flows is still not fully understood. We focus in our work on characterising the interfacial instability as well as associated interfacial waves in vertical laminar-laminar gas-liquid flows over a wide range of parameters covering different flow regimes, i.e. counter-current, zero-interface velocity (loading) and partial-to-full liquid flow reversal (flooding). High-resolution direct numerical simulations using the TPLS flow solver (http://sourceforge.net/projects/tpls/) reveal the existence of weakly nonlinear interfacial waves, which are in good agreement with Stuart-Landau theory. These waves travel down- or upstream, depending on the flow regime. Furthermore, spatio-temporal linear stability analysis indicates the occurrence of absolute instability within the investigated parameter range. DNS is used to analyse this feature in more detail whereby agreement with linear theory has been established.

  2. Two phase flow of liquids in a narrow gap: Phase interference and hysteresis

    NASA Astrophysics Data System (ADS)

    Raza, Salim; Hejazi, S. Hossein; Gates, Ian D.

    2016-07-01

    Co-current flow of two immiscible liquids, such as oil and water in a planar fracture, exhibits nonlinear structures which become important in many natural and engineering systems such as subsurface flows, multiphase flows in lubrication joints, and coating flows. In this context, co-current flow of oil and water with variable rates is experimentally studied in a Hele-Shaw cell, various flow regimes are classified, and relative permeabilities for the phases are analysed thoroughly. Similar to multiphase pipe flows, multiphase flow in planar gaps shows various flow regimes, each having different flow rate/pressure gradient behaviour. As well as recovering the known results in the immiscible displacements in Hele-Shaw cell where the fluid-fluid interface remains stable/unstable for favorable/adverse viscosity ratios, it is found that the co-current flow of two fluids with different viscosities results in three distinct flow regimes. Before breakthrough of non-wetting phase, i.e, water, a "linear displacement" flow regime initially establishes at very low water injection rates. This stable movement turns into a "fingering advancement" flow regime at high water flow rates and Saffman-Taylor instability develops normal to the direction of the flow. After the breakthrough, a "droplet formation" flow regime is identified where the droplets of wetting phase, oil, are trapped in the water phase. For subsurface flow applications, we quantify these regimes through relative permeability curves. It is reported that as the water flow rate increases, the relative permeabilities and flow channels become smooth and regular. This behaviour of relative permeability and saturations shows dominance of capillary forces at low flow rates and viscous forces at higher flow rates. Variable injection rates provide the interface structures for both drainage and imbibition process, where the wetting phase saturation decreases and increases respectively. It is shown that relative permeability

  3. Chromatographic sample collection from two-phase (gas+liquid) flows.

    PubMed

    Bruno, Thomas J; Windom, Bret C

    2011-12-01

    A particularly challenging sample presentation in analytical chemistry is a flowing stream that consists of both a gas and liquid phase, combined with the common situation in which a reliable analysis is needed for both phases, separately. In these cases, the vapor and liquid must be physically separated (without change to either), before the individual phases can be collected and analyzed. It is not possible to analyze two-phase flows otherwise. Although the two phases are at equilibrium, it is imperative that no liquid contaminate the vapor, and no vapor be entrained in the liquid at a given temperature and pressure. In this paper, we describe a simple on-line device that can individually separate and collect the vapor and liquid phases of a two-phase flow. The apparatus, which we call P(2)SC, uses an adaptation of the branch point separator, with vapor collection done downstream in a metal bellows. The liquid collection is done in a length of Teflon tube. The separated vapor and liquid phases are then easily transferred into any desired analytical instrument with a syringe, although any sample introduction method, such as a valve, could be used as well. We discuss the application of this device with a stream of thermally stressed rocket kerosene. PMID:22036084

  4. Cycle-Induced Flow and Transport in an Alveolus Partially Filled with Liquid

    NASA Astrophysics Data System (ADS)

    Wei, Hsien-Hung; Benintendi, Steven W.; Halpern, David; Grotberg, James B.

    2001-11-01

    The flow and transport in an alveolus are of fundamental importance to partial liquid ventilation, surfactant transport, pulmonary drug administration, and gene therapy. A simplified model is developed for alveolar liquid lining undergoing cyclic stretching which mimics breathing motions. A thin, viscous film coats an extensible slot with small aspect ratio and strained amplitude. We apply scaling analysis and asymptotic theory to describe the interface profile and surfactant distribution during the oscillation cycle for either insoluble or soluble surfactants. The flow consists of two distinct regimes: a near-parallel flow region and a non-parallel flow, end region near the slot pinned wall. Non-zero cycle-averaged flows are shown and their turning directions near the pinned wall depend on the parameters of the system. We also model the case when the liquid is partially filled in the alveolus and has a comparable thickness to the size of the alveolus. The surfactant-free case is first investigated. By assuming a spherical interface due to small capillary number, we solve the Stokes flow analytically in the toroidal coordinate system. For small liquid volume, the flow field is dominated by the normal velocity component while large liquid volume leads to vortex structures near the alveolar opening. The flow is zero cycle-averaged. However, when the interface is deformed away from a spherical shape or surfactants are present, a non-zero cycle-averaged flow is expected. The research is supported by grants NASA NAG3-2196, NIH HL41126 and HL64373.

  5. Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy

    SciTech Connect

    Gawelda, W.; Pham, V. T.; El Nahhas, A.; Kaiser, M.; Zaushitsyn, Y.; Bressler, C.; Chergui, M.; Johnson, S. L.; Grolimund, D.; Abela, R.; Hauser, A.

    2007-02-02

    We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy)3 at room temperature.

  6. Thermoelectric magnetohydrodynamic and thermocapillary driven flows of liquid conductors in magnetic fields

    NASA Astrophysics Data System (ADS)

    Jaworski, Michael Andrew

    The Solid/Liquid Lithium Divertor experiment (SLiDE) has been designed, constructed and operated in order to determine the behavior of these liquid conductors in a magnetic field with imposed thermal gradients. Liquid lithium is chosen for its applicability to fusion systems as well as recent demonstrations of its ability to passively redistribute incident heat fluxes on the order of 50[MW/m2]. The lithium is contained within a stainless steel tray that is actively cooled and contains a set of temperature diagnostics for analysis of the heat, flux coming from the tray. The system is magnetized by a set of external magnets and a linear electron beam is used to create heat fluxes similar to those found in fusion divertors. Surface velocity of the liquid lithium is measured with a digital camera. A theory explaining the balance between thermoelectric magnetohydrodynamics and thero-capillary driven, free-surface flows in containers of arbitrary type in a magnetized environment has been developed. A new dimensionless group depending on the thermoelectric power of the liquid/container pair, the physical properties of the liquid and solid and the flow geometry has been found that determines which mechanism, TC or TEMHD, is the dominant effect in any given system. Experiments show that TEMHD dominates the flow in SLiDE, consistent with the theory governing these flows. This is verified by series of qualitative experiments, as well as quantitative comparison with theoretical flow predictions. This constitutes the first direct observation of TEMHD driven flow yet reported in the literature. Application of the developed theory indicates liquid lithium fusion systems will operate in a TEMHD dominated regime. Technologies suggested by the exploitation of TEMHD pumping are also presented.

  7. Effect of unsaturation on the absorption of ethane and ethylene in imidazolium-based ionic liquids.

    PubMed

    Moura, Leila; Mishra, Manas; Bernales, Varinia; Fuentealba, Patricio; Padua, Agilio A H; Santini, Catherine C; Costa Gomes, Margarida F

    2013-06-20

    The influence of the presence of imidazolium side chain unsaturation on the solubility of ethane and ethylene was studied in three ionic liquids: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide-saturated alkyl side-chain in the cation; 1-methyl-3-(buten-3-yl)imidazolium bis(trifluorosulfonyl)imide-double bond in the side-chain of the cation; and 1-methyl-3-benzylimidazolium bis(trifluorosulfonyl)imide-benzyl group in the side-chain of the cation. The solubility of both gases decreases when the side-chain of the cations is functionalized with an unsaturated group. This can be explained by a less favorable enthalpy of solvation. The difference of solubility between ethane and ethylene can be explained from a balance of enthalpic and entropic factors: for the ionic liquid with the saturated alkyl side-chain and the benzyl-substituted side-chain, it is the favorable entropy of solvation that explains the larger ethylene solubility, whereas in the case of the saturated side-chain, it is the more favorable enthalpy of solvation. Molecular simulation allowed the identification of the mechanisms of solvation and the preferential solvation sites for each gas in the different ionic liquids. Simulations have shown that the entropy of solvation is more favorable when the presence of the gas weakens the cation-anion interactions or when the gas can be solvated near different sites of the ionic liquid. PMID:23713882

  8. In situ monitoring of atmospheric nitrous acid based on multi-pumping flow system and liquid waveguide capillary cell.

    PubMed

    Liu, Yuhan; Lu, Keding; Dong, Huabin; Li, Xin; Cheng, Peng; Zou, Qi; Wu, Yusheng; Liu, Xingang; Zhang, Yuanhang

    2016-05-01

    In the last four decades, various techniques including spectroscopic, wet chemical and mass spectrometric methods, have been developed and applied for the detection of ambient nitrous acid (HONO). We developed a HONO detection system based on long path photometry which consists of three independent modules i.e., sampling module, fluid propulsion module and detection module. In the propulsion module, solenoid pumps are applied. With solenoid pumps the pulsed flow can be computer controlled both in terms of pump stroke volume and pulse frequency, which enables the attainment of a very stable flow rate. In the detection module, a customized Liquid Waveguide Capillary Cell (LWCC) is used. The customized LWCC pre-sets the optical fiber in-coupling with the liquid wave guide, providing the option of fast startup and easy maintenance of the absorption photometry. In summer 2014, our system was deployed in a comprehensive campaign at a rural site in the North China Plain. More than one month of high quality HONO data spanning from the limit of detection to 5ppb were collected. Intercomparison of our system with another established system from Forschungszentrum Juelich is presented and discussed. In conclusion, our instrument achieved a detection limit of 10pptV within 2min and a measurement uncertainty of 7%, which is well suited for investigation of the HONO budget from urban to rural conditions in China. PMID:27155434

  9. Numerical simulation of cavitating flow of liquid helium in venturi channel

    NASA Astrophysics Data System (ADS)

    Ishimoto, Jun; Kamijo, Kenjiro

    2003-01-01

    The fundamental characteristics of the two-dimensional cavitating flow of liquid helium through a venturi channel near the lambda point are numerically investigated to realize the further development and high performance of new multi-phase superfluid cooling systems. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model with generalized curvilinear coordinates system are presented, and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the cavitating flow of liquid helium though venturi channel is shown in detail, and it is also found that the generation of superfluid counterflow against normal fluid flow based on the thermomechanical effect is conspicuous in the large gas phase volume fraction region where the liquid-to-gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase.

  10. Numerical Simulation of Cavitating Flow of Liquid Helium in a Vertical Converging-Diverging Nozzle

    NASA Astrophysics Data System (ADS)

    Ishimoto, J.; Kamijo, K.

    2004-06-01

    The basic characteristics of the two-dimensional cavitating flow of liquid helium through a vertical converging-diverging nozzle near the lambda point are numerically investigated to realize the further development and high performance of new multiphase He II cooling systems. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model with generalized curvilinear coordinates system are presented, and several multiphase flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the cavitating flow of liquid helium though a vertical converging-diverging nozzle is shown in detail, and it is also found that the generation of superfluid counterflow against normal fluid flow based on the thermomechanical effect is conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase.

  11. Numerical Analysis of Cavitating Flow of Liquid Helium inHorizontal Converging-Diverging Channel

    NASA Astrophysics Data System (ADS)

    Ishimoto, Jun; Kamijo, Kenjiro

    The basic characteristics of the two-dimensional cavitating flow of liquid helium through a horizontal converging-diverging channel near the lambda point are numerically investigated to realize the further development and high performance of new multiphase superfluid cooling systems. First, the governing equations of the cavitating flow of liquid helium based on the unsteady thermal nonequilibrium multifluid model with generalized curvilinear coordinates system are presented, and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the cavitating flow of liquid helium though horizontal converging-diverging channel is shown in detail, and it is also found that the generation of superfluid counterflow against normal fluid flow based on the thermo mechanical effect is conspicuous in the large gas phase volume fraction region where the liquid- to gas-phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase.

  12. Design and Fabrication of a MEMS Flow Sensor and Its Application in Precise Liquid Dispensing

    PubMed Central

    Liu, Yaxin; Chen, Liguo; Sun, Lining

    2009-01-01

    A high speed MEMS flow sensor to enhance the reliability and accuracy of a liquid dispensing system is proposed. Benefitting from the sensor information feedback, the system can self-adjust the open time of the solenoid valve to accurately dispense desired volumes of reagent without any pre-calibration. First, an integrated high-speed liquid flow sensor based on the measurement of the pressure difference across a flow channel is presented. Dimensions of the micro-flow channel and two pressure sensors have been appropriately designed to meet the static and dynamic requirements of the liquid dispensing system. Experiments results show that the full scale (FS) flow measurement ranges up to 80 μL/s, with a nonlinearity better than 0.51% FS. Secondly, a novel closed-loop control strategy is proposed to calculate the valve open time in each dispensing cycle, which makes the system immune to liquid viscosity, pressure fluctuation, and other sources of error. Finally, dispensing results show that the system can achieve better dispensing performance, and the coefficient of variance (CV) for liquid dispensing is below 3% at 1 μL and below 4% at 100 nL. PMID:22408517

  13. Investigation of liquid phase axial dispersion in Taylor bubble flow by radiotracer residence time distribution analysis

    NASA Astrophysics Data System (ADS)

    Chughtai, I. R.; Iqbal, W.; Din, G. U.; Mehdi, S.; Khan, I. H.; Inayat, M. H.; Jin, J. H.

    2013-05-01

    A gas-liquid Taylor bubble flow occurs in small diameter channels in which gas bubbles are separated by slugs of pure liquid. This type of flow regime is well suited for solid catalyzed gas-liquid reactors in which the reaction efficiency is a strong function of axial dispersion in the regions of pure liquid. This paper presents an experimental study of liquid phase axial dispersion in a Taylor bubble flow developed in a horizontal tube using high speed photography and radiotracer residence time distribution (RTD) analysis. A parametric dependence of axial dispersion on average volume fraction of gas phase was also investigated by varying the relative volumetric flow rates of the two phases. 137mBa produced from a 137Cs/137mBa radionuclide generator was used as radiotracer and measurements were made using the NaI(Tl) scintillation detectors. Validation of 137mBa in the form of barium chloride as aqueous phase radiotracer was also carried out. Axial Dispersion Model (ADM) was used to simulate the hydrodynamics of the system and the results of the experiment are presented. It was observed that the system is characterized by very high values of Peclet Number (Pe˜102) which reveals an approaching plug type flow. The experimental and model estimated values of mean residence times were observed in agreement with each other.

  14. Profiles of flow discharged from vertical rotating pipes: A contrast between inviscid liquid and granular jets

    NASA Astrophysics Data System (ADS)

    Weidman, P. D.; Kubitschek, J. P.; Medina, A.

    2008-11-01

    The stability of viscous rotating liquid columns and their application to rotating viscous liquid jets aligned under gravity is reviewed. Experiments on stable viscous fluid flow discharged from rotating vertical pipes exhibit very weak contraction. We present an elementary liquid jet analysis to understand this phenomenon. Indeed, our inviscid model of a slender rotating inviscid liquid jet shows that rotation suppresses contraction. Next we study the comparable problem for granular flow. Our model for noncohesive granular flow emanating from a vertical pipe rotating about its central axis, valid for sufficiently large rotation rate, shows that the granular profiles blossom rather than contract. The profiles of both the liquid and granular jets depend on the same dimensionless parameters—an exit Froude number Fr0 and an exit swirl parameter χ0. The limitations of both models are discussed. Experimental data for granular jet profiles compare well with the collision-free granular flow model in its range of applicability. A criterion for the rotation rate at which particles adjacent to the inner wall of the rotating pipe cease to flow is also given and compared to experiment.

  15. Physical understanding of gas-liquid annular flow and its transition to dispersed droplets

    NASA Astrophysics Data System (ADS)

    Kumar, Parmod; Das, Arup Kumar; Mitra, Sushanta K.

    2016-07-01

    Transformation from annular to droplet flow is investigated for co-current, upward gas-liquid flow through a cylindrical tube using grid based volume of fluid framework. Three transitional routes, namely, orificing, rolling, and undercutting are observed for flow transformation at different range of relative velocities between the fluids. Physics behind these three exclusive phenomena is described using circulation patterns of gaseous phase in the vicinity of a liquid film which subsequently sheds drop leading towards transition. Orifice amplitude is found to grow exponentially towards the core whereas it propagates in axial direction in a parabolic path. Efforts have been made to fit the sinusoidal profile of wave structure with the numerical interface contour at early stages of orificing. Domination of gas inertia over liquid flow has been studied in detail at the later stages to understand the asymmetric shape of orifice, leading towards lamella formation and droplet generation. Away from comparative velocities, circulations in the dominant phase dislodge the drop by forming either a ligament (rolling) or a bag (undercut) like protrusion in liquid. Study of velocity patterns in the plane of droplet dislodge reveals the underlying physics behind the disintegration and its dynamics at the later stages. Using numerical phase distributions, rejoining of dislodged droplet with liquid film as post-rolling consequences has been also proposed. A flow pattern map showing the transitional boundaries based on the physical mechanism is constructed for air-water combination.

  16. Theoretical interpretation of the vacuum ultraviolet reflectance of liquid helium and of the absorption spectra of helium microbubbles in aluminum

    NASA Astrophysics Data System (ADS)

    Lucas, A. A.; Vigneron, J. P.; Donnelly, S. E.; Rife, J. C.

    1983-09-01

    The position and width of the helium resonance line 11S0-->21P1 are calculated for a high-density helium fluid. The theory aims at understanding the reflectivity data of Surko et al. for the low-temperature liquid-vapor interface and the absorption data of Rife et al. for room-temperature, high-pressure helium bubbles in aluminum. The theoretical ingredients of the model are (i) the long-range dipole interaction of an excited 2P atom with the rest of the fluid and with the metal substrate; (ii) the short-range Pauli pseudorepulsion arising from orthogonalization of the 2p-electron wave function with the 1s ground-state orbital of neighboring atoms; (iii) a statistical treatment of the high-density fluid based either on the experimentally measured radial pair distribution function of low-T liquid He, or on the Percus-Yevick distribution function of hard spheres and the theoretical equation of state of Young et al. for the He fluid in the bubbles; (iv) the standard static line-broadening theory to calculate the effect of Pauli repulsion on the line shapes. The theory provides a reasonably accurate understanding of the observed spectra in both the liquid and high-density gas, and can serve as a sound basis for interpretation of vacuum ultraviolet spectra in other gas-metal combinations.

  17. Flow visualization and characterization of evaporating liquid drops

    NASA Technical Reports Server (NTRS)

    Chao, David F. (Inventor); Zhang, Nengli (Inventor)

    2004-01-01

    An optical system, consisting of drop-reflection image, reflection-refracted shadowgraphy and top-view photography, is used to measure the spreading and instant dynamic contact angle of a volatile-liquid drop on a non-transparent substrate. The drop-reflection image and the shadowgraphy is shown by projecting the images of a collimated laser beam partially reflected by the drop and partially passing through the drop onto a screen while the top view photograph is separately viewed by use of a camera video recorder and monitor. For a transparent liquid on a reflective solid surface, thermocapillary convection in the drop, induced by evaporation, can be viewed nonintrusively, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this technique clearly reveal that evaporation and thermocapillary convection greatly affect the spreading process and the characteristics of dynamic contact angle of the drop.

  18. Effects of heat generation or absorption on mixed convection flow over a stretching porous wedge with convective boundary condition

    NASA Astrophysics Data System (ADS)

    Ashraf, M.; Narahari, M.; Muthuvalu, Mohana Sundaram

    2014-10-01

    The series solution of the boundary layer flow over a permeable stretching wedge with convective boundary condition has been investigated in the presence of heat generation or absorption effects. The governing coupled non-linear partial differential equations are transformed to dimensionless system of coupled non-linear ordinary differential equations using the similarity variables and then solved by Homotopy Analysis Method (HAM). An analysis of the results shows that the velocity and temperature fields are significantly influenced by the velocity ratio parameter, wedge angle parameter, suction/injection parameter, heat generation/absorption parameter and convective heat transfer parameter.

  19. Pool boiling enhancement through bubble induced convective liquid flow in feeder microchannels

    NASA Astrophysics Data System (ADS)

    Jaikumar, A.; Kandlikar, S. G.

    2016-01-01

    Bubbles departing from the nucleation sites induce a liquid flow from the bulk to the heated surface during pool boiling. Alternating the nucleating regions with non-nucleating regions facilitates separate liquid-vapor pathways for departing vapor bubbles and returning liquid. We explored an additional enhancement through liquid feeder channels on the heater surface directing the returning liquid towards the nucleating region. The nucleating bubbles were confined to the nucleating region as the returning liquid flow induced strong convective currents over the non-nucleating regions. In the best performing configuration, the nucleating regions were 0.5 mm wide, separated by non-nucleating regions of width 2.125 mm, which corresponded to the bubble departure diameter. The non-nucleating regions contained 0.5 mm wide feeder channels directing liquid towards the nucleating region. High speed images indicated distinct vapor columns over the nucleating regions with liquid channeled through the feeder channels. At higher heat fluxes, the strong liquid currents established over the feeder channels suppressed any undesirable nucleation in them keeping the separated vapor-liquid pathways functional. This enhancement technique resulted in a critical heat flux of 394 W/cm2 at a wall superheat of 5.5 °C which translated to a heat transfer coefficient of 713 kW/m2 °C. The additional surface area and high heat transfer coefficient due to microchannel flow in feeder channels, and the unobstructed surface available for the bubbles to expand over the prime heat transfer surface area before departing were seen to be responsible for their superior performance.

  20. Bubble Generation in a Continuous Liquid Flow Under Reduced Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Pais, Salvatore Cezar

    1999-01-01

    The present work reports a study of bubble generation under reduced gravity conditions for both co-flow and cross-flow configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an air-water system. Three different flow tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of air injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric flow rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing air injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the flow configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence flow regime transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric flow rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly flow regime. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed

  1. Accelerated gas-liquid visible light photoredox catalysis with continuous-flow photochemical microreactors.

    PubMed

    Straathof, Natan J W; Su, Yuanhai; Hessel, Volker; Noël, Timothy

    2016-01-01

    In this protocol, we describe the construction and use of an operationally simple photochemical microreactor for gas-liquid photoredox catalysis using visible light. The general procedure includes details on how to set up the microreactor appropriately with inlets for gaseous reagents and organic starting materials, and it includes examples of how to use it to achieve continuous-flow preparation of disulfides or trifluoromethylated heterocycles and thiols. The reported photomicroreactors are modular, inexpensive and can be prepared rapidly from commercially available parts within 1 h even by nonspecialists. Interestingly, typical reaction times of gas-liquid visible light photocatalytic reactions performed in microflow are lower (in the minute range) than comparable reactions performed as a batch process (in the hour range). This can be attributed to the improved irradiation efficiency of the reaction mixture and the enhanced gas-liquid mass transfer in the segmented gas-liquid flow regime. PMID:26633128

  2. Liquid-Liquid Displacement Flows in a Hele-Shaw Cell including Viscoplastic Effects

    NASA Astrophysics Data System (ADS)

    de Souza Mendes, Paulo R.; Varges, Priscilla R.

    2008-07-01

    Viscous fingering in non-Newtonian fluids in a rectangular Hele-Shaw cell is investigated. This cell is filled with aqueous solutions of carbopol in two different concentrations. A Newtonian mineral oil is then injected into the cell and the displacement is observed. A digital camera is used to capture images of the interface between the fluids during the flow. Applications include displacement of heavy crude oil in reservoirs. The main parameters that govern this flow are the viscosity ratio, the rheological capillary number, and the (dimensionless) flow rate. The interface shape is given for two different values of flow rate and viscosity ratio.

  3. Velocity and flow rate measurement of liquid metal by contactless electromagnetic Lorentz force technique

    NASA Astrophysics Data System (ADS)

    Dubovikova, N.; Karcher, C.; Kolesnikov, Y.

    2016-07-01

    Providing flow analysis in case of aggressive and hot liquids is a complicated task, especially when liquid's composition and, hence, its physical properties, are unknown. Contactless techniques are the most promising methods for liquid metal flow rate control and some of these methods are based on electromagnetic induction of breaking force acting on an electrically conductive fluid which is moving through a magnetic field. One of the techniques is time-of-flight Lorentz force velocimetry (LFV). By using the method one can estimate volumetric flow rate without knowing of electrical conductivity, magnitude of magnetic field or characteristic dimension. The most important and crucial challenge within the technique is detection of small fluctuations of Lorentz force value. In this article we will focus on application and investigation of time-of-flight LFV.

  4. Self-Powered Triboelectric Micro Liquid/Gas Flow Sensor for Microfluidics.

    PubMed

    Chen, Jie; Guo, Hengyu; Zheng, Jiangeng; Huang, Yingzhou; Liu, Guanlin; Hu, Chenguo; Wang, Zhong Lin

    2016-08-23

    Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble via the capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor's detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system. PMID:27490518

  5. Surface study of metal-containing ionic liquids by means of photoemission and absorption spectroscopies

    NASA Astrophysics Data System (ADS)

    Caporali, Stefano; Pedio, Maddalena; Chiappe, Cinzia; Pomelli, Christian S.; Acres, Robert G.; Bardi, Ugo

    2016-06-01

    The vacuum/liquid interface of different ionic liquids obtained by dissolving bistriflimide salts of Ag, Al, Cu, Ni, and Zn in 1-butyl-3-methylimidazolium bistriflimide ([bmim][Tf2N]) was investigated under vacuum using AR-XPS and NEXAFS. The XPS spectra show chemical shifts of the nitrogen of the bistriflimide anion as a function of the metal type, indicating different strength of the coordination bonds. In silver bearing ILs, silver ions were found to be only weakly coordinated. On the contrary, Ni, Cu, Zn, and especially Al exhibit large chemical shifts attributable to strong interaction with the bistriflimide ions. The outermost surface was enriched with or depleted of metal ions as a function of the nature of the metals. Nickel and zinc tend to slightly concentrate at the surface while copper, silver, and especially aluminum are depleted at the surface. We also observed that the aliphatic alkyl chains of the cations tend to protrude outside the surface in all systems studied. However, the presence of metals generally increases the amount of bistriflimide at the vacuum/liquid interface.

  6. Magnetohydrodynamic generators using two-phase liquid-metal flows

    NASA Technical Reports Server (NTRS)

    Petrick, M.

    1969-01-01

    Two-phase flow generator cycle of a magnetohydrodynamic /MHD/ generator uses a working fluid which is compressible and treated as an expanding gas. The two-phase mixture passes from the heat source through the MHD generator, where the expansion process takes place and the electrical energy is extracted.

  7. Modelling of evaporation of a dispersed liquid component in a chemically active gas flow

    NASA Astrophysics Data System (ADS)

    Kryukov, V. G.; Naumov, V. I.; Kotov, V. Yu.

    1994-01-01

    A model has been developed to investigate evaporation of dispersed liquids in chemically active gas flow. Major efforts have been directed at the development of algorithms for implementing this model. The numerical experiments demonstrate that, in the boundary layer, significant changes in the composition and temperature of combustion products take place. This gives the opportunity to more correctly model energy release processes in combustion chambers of liquid-propellant rocket engines, gas-turbine engines, and other power devices.

  8. Handling of liquid holdup in Duyong two-phase flow pipeline system

    SciTech Connect

    Saad, M.R.; Singh, B. )

    1988-01-01

    This paper deals with the handling of liquids in the multi-phase flow pipeline system within Carigali's Duyong Offshore Gas Complex and the Onshore Gas Terminal, in Kerteh, Terongganu. The data and operations experience gathered necessitate changes to the operating procedures originally identified during the design phase. This is to ensure more efficient handling of liquid hold-up in the pipeline during low gas flowrates.

  9. Immersed boundary method for the MHD flows of liquid metals

    NASA Astrophysics Data System (ADS)

    Grigoriadis, D. G. E.; Kassinos, S. C.; Votyakov, E. V.

    2009-02-01

    Wall-bounded magnetohydrodynamic (MHD hereafter) flows are of great theoretical and practical interest. Even for laminar cases, MHD simulations are associated with very high computational cost due to the resolution requirements for the Hartmann and side layers developing in the presence of solid obstacles. In the presence of turbulence, these difficulties are further compounded. Thus, MHD simulations in complex geometries are currently a challenge. The immersed boundary (IB hereafter) method is a reliable numerical tool for efficient hydrodynamic field simulations in arbitrarily geometries, but it has not yet been extended for MHD simulations. The present study forms the first attempt to apply the IB methodology for the computation of both the hydrodynamic and MHD fields. A consistent numerical methodology is presented that is appropriate for efficient 3D MHD simulations in geometrically complicated domains using cartesian flow solvers. For that purpose, a projection scheme for the electric current density is presented, based on an electric potential correction algorithm. A suitable forcing scheme for electric density currents in the vicinity of non-conducting immersed surfaces is also proposed. The proposed methodology has been first extensively tested for Hartmann layers in fully-developed and developing channel and duct flows at Hartmann numbers Ha=500-2000. In order to demonstrate the potential of the method, the three-dimensional MHD flow around a circular cylinder at Reynolds number Re=200 is also presented. The effects of grid resolution and variable arrangement on the simulation accuracy and consistency were examined. When compared with existing numerical or analytic solutions, excellent agreement was found for all the cases considered. The proposed projection and forcing schemes for current densities were found capable of satisfying the charge conservation law in the presence of immersed non-conducting boundaries. Finally, we show how the proposed

  10. The Discrete Multi-Hybrid System for the Simulation of Solid-Liquid Flows

    PubMed Central

    Alexiadis, Alessio

    2015-01-01

    This study proposes a model based on the combination of Smoothed Particle Hydrodynamics, Coarse Grained Molecular Dynamics and the Discrete Element Method for the simulation of dispersed solid-liquid flows. The model can deal with a large variety of particle types (non-spherical, elastic, breakable, melting, solidifying, swelling), flow conditions (confined, free-surface, microscopic), and scales (from microns to meters). Various examples, ranging from biological fluids to lava flows, are simulated and discussed. In all cases, the model captures the most important features of the flow. PMID:25961561

  11. Suppressing turbulence and enhancing liquid suspension flow in pipelines with electrorheology

    NASA Astrophysics Data System (ADS)

    Tao, R.; Gu, G. Q.

    2015-01-01

    Flows through pipes, such as crude oil through pipelines, are the most common and important method of transportation of fluids. To enhance the flow output along the pipeline requires reducing viscosity and suppressing turbulence simultaneously and effectively. Unfortunately, no method is currently available to accomplish both goals simultaneously. Here we show that electrorheology provides an efficient solution. When a strong electric field is applied along the flow direction in a small section of pipeline, the field polarizes and aggregates the particles suspended inside the base liquid into short chains along the flow direction. Such aggregation breaks the rotational symmetry and makes the fluid viscosity anisotropic. In the directions perpendicular to the flow, the viscosity is substantially increased, effectively suppressing the turbulence. Along the flow direction, the viscosity is significantly reduced; thus the flow along the pipeline is enhanced. Recent field tests with a crude oil pipeline fully confirm the theoretical results.

  12. A visual study of radial inward choked flow of liquid nitrogen.

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Simoneau, R. J.; Hsu, Y. Y.

    1973-01-01

    Data and high speed movies were acquired on pressurized subcooled liquid nitrogen flowing radially inward through a 0.0076 cm gap. The stagnation pressure ranged from 0.7 to 4 MN/sq m. Steady radial inward choked flow appears equivalent to steady choked flow through axisymmetric nozzles. Transient choked flows through the radial gap are not uniform and the discharge pattern appears as nonuniform impinging jets. The critical mass flow rate data for the transient case appear different from those for the steady case. On the mass flow rate vs pressure map, the slope and separation of the isotherms appear to be less for transient than for steady radial choked flow.

  13. Computation of turbulent flow in a thin liquid layer of fluid involving a hydraulic jump

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.

    1991-01-01

    Numerically computed flow fields and free surface height distributions are presented for the flow of a thin layer of liquid adjacent to a solid horizontal surface that encounters a hydraulic jump. Two kinds of flow configurations are considered: two-dimensional plane flow and axisymmetric radial flow. The computations used a boundary-fitted moving grid method with a k-epsilon model for the closure of turbulence. The free surface height was determined by an optimization procedure which minimized the error in the pressure distribution on the free surface. It was also checked against an approximate procedure involving integration of the governing equations and use of the MacCormack predictor-corrector method. The computed film height also compared reasonably well with previous experiments. A region of recirculating flow was found to be present adjacent to the solid boundary near the location of the jump, which was caused by a rapid deceleration of the flow.

  14. Evaluation of a ferroelectric tunnel junction by ultraviolet-visible absorption using a removable liquid electrode.

    PubMed

    Lee, Hong-Sub; Kang, Kyung-Mun; Yeom, Geun Young; Park, Hyung-Ho

    2016-05-27

    Ferroelectric memristors offer a significant alternative to their redox-based analogs in resistive random access memory because a ferroelectric tunnel junction (FTJ) exhibits a memristive effect that induces resistive switching (RS) regardless of the operating current level. This RS results from a change in the ferroelectric polarization direction, allowing the FTJ to overcome the restriction encountered in redox-based memristors. Herein, the memristive effect of an FTJ was investigated by ultraviolet-visible (UV-Vis) absorption spectroscopy using a removable mercury (Hg) top electrode (TE), BaTiO3 (BTO) ferroelectric tunnel layer, La0.7Sr0.3MnO3 (LSMO) semiconductor bottom electrode, and wide-bandgap quartz (100) single-crystal substrate to determine the low-resistance state (LRS) and high-resistance state (HRS) of the FTJ. A BTO (110)/LSMO (110) polycrystal memristor involving a Hg TE showed a small memristive effect (switching ratio). This effect decreased with increasing read voltage because of a small potential barrier height. The LRS and HRS of the FTJ showed quasi-similar UV-Vis absorption spectra, consistent with the small energy difference between the valence-band maximum of BTO and Fermi level of LSMO near the interface between the LRS and HRS. This energy difference stemmed from the ferroelectric polarization and charge-screening effect of LSMO based on an electrostatic model of the FTJ. PMID:27087674

  15. Evaluation of a ferroelectric tunnel junction by ultraviolet–visible absorption using a removable liquid electrode

    NASA Astrophysics Data System (ADS)

    Lee, Hong-Sub; Kang, Kyung-Mun; Yeom, Geun Young; Park, Hyung-Ho

    2016-05-01

    Ferroelectric memristors offer a significant alternative to their redox-based analogs in resistive random access memory because a ferroelectric tunnel junction (FTJ) exhibits a memristive effect that induces resistive switching (RS) regardless of the operating current level. This RS results from a change in the ferroelectric polarization direction, allowing the FTJ to overcome the restriction encountered in redox-based memristors. Herein, the memristive effect of an FTJ was investigated by ultraviolet–visible (UV–Vis) absorption spectroscopy using a removable mercury (Hg) top electrode (TE), BaTiO3 (BTO) ferroelectric tunnel layer, La0.7Sr0.3MnO3 (LSMO) semiconductor bottom electrode, and wide-bandgap quartz (100) single-crystal substrate to determine the low-resistance state (LRS) and high-resistance state (HRS) of the FTJ. A BTO (110)/LSMO (110) polycrystal memristor involving a Hg TE showed a small memristive effect (switching ratio). This effect decreased with increasing read voltage because of a small potential barrier height. The LRS and HRS of the FTJ showed quasi-similar UV–Vis absorption spectra, consistent with the small energy difference between the valence-band maximum of BTO and Fermi level of LSMO near the interface between the LRS and HRS. This energy difference stemmed from the ferroelectric polarization and charge-screening effect of LSMO based on an electrostatic model of the FTJ.

  16. Magnetohydrodynamic flow in the liquid phase for a specific pool boiling scenario

    NASA Astrophysics Data System (ADS)

    Bühler, Leo

    2002-11-01

    In the EVOLVE concept for a nuclear fusion blanket a pool boiling scenario has been proposed where a number of permanent vertical vapour channels are formed in a horizontal layer of liquid lithium. Similar situations occur during laser beam welding where a relatively long vapour capillary is observed. The present analysis focuses on the flow of the electrically conducting liquid phase in the presence of a strong uniform horizontal magnetic field. The cross-section of vapour channels is circular if surface tension dominates magnetic forces. In the opposite case a stretching of the liquid vapour interface along magnetic field lines is observed and contours become possible where a major part of the interface is straight and aligned with the field. For strong magnetic fields the liquid flow exhibits several distinct subregions. Most of the liquid domain is occupied by inviscid cores. These are separated from each other by parallel layers that spread along the field lines which are tangential to the vapour channel. In one core, which is located between two parallel layers, the flow direction is preferentially oriented along magnetic field lines, while in the other cores the flow is perpendicular to the field.

  17. Effects of Erosion Angle on Erosion Properties of Fe-B Alloy in Flowing Liquid Zinc

    NASA Astrophysics Data System (ADS)

    Liu, Guangzhu; Xing, Jiandong; Ma, Shengqiang; He, Yaling; Fu, Hanguang; Gao, Yuan; Wang, Yong; Wang, Yiran

    2015-05-01

    The effect of erosion angle on erosion behavior of the as-cast Fe-B alloy in flowing liquid zinc was investigated. The results show that the erosion rate of Fe-B alloy decreases linearly with increasing erosion angle. The erosion resistance of Fe-B alloy is better than that of 316L stainless steel, which is attributed to the favorable barrier effect of net-like Fe2B that resists erosion by flowing liquid zinc. Meanwhile, the ductile matrix can provide support in preventing borides from spalling and borides cause barrier effect on flowing liquid zinc during liquid zinc erosion, which shows a synergistic erosion-corrosion behavior between the matrix and borides. Moreover, an increase in erosion angle can cause a decrease in the removal effect of the flowing liquid zinc scouring component on the erosion compounds. Therefore, the quantity of erosion compounds increases at the erosion interface, weakening the mass transfer process and decreasing the erosion rate of the Fe-B alloy.

  18. Modelling of liquid metal flow and oxide film defects in filling of aluminium alloy castings

    NASA Astrophysics Data System (ADS)

    Dai, X.; Jolly, M.; Yang, X.; Campbell, J.

    2012-07-01

    The liquid metal flow behaviours in different runner system designs have important effects on the mechanical strength of aluminium alloy castings. In this paper, a new model has been developed which is a two-dimensional program using a finite difference technique and the Marker and Cell (MAC) method to simulate the flow of liquid metal during filling a mould. In the program the Eulerian method has been used for the liquid metal flow, while the Oxide Film Entrainment Tracking Algorithm (OFET) method (a Lagrangian method) has been used to simulate the movement of the oxide film on the liquid metal surface or in the liquid metal flow. Several examples have been simulated and tested and the relevant results were obtained. These results were compared with measured bending strengths. It was found that the completed program was capable of simulating effectively the filling processes of different runner systems. The simulation results are consistent with the experiment. In addition, the program is capable of providing clearer images for predicting the distribution of the oxide film defects generated during filling a mould.

  19. Experiments on Heat Transfer in a Thin Liquid Film Flowing Over a Rotating Disk

    NASA Technical Reports Server (NTRS)

    Sankaran, Subramanian (Technical Monitor); Ozar, B.; Cetegen, B. M.; Faghri, A.

    2004-01-01

    An experimental study of heat transfer into a thin liquid film on a rotating heated disk is described. Deionized water was introduced at the center of a heated. horizontal disk with a constant film thickness and uniform radial velocity. Radial distribution of the disk surface temperatures was measured using a thermocouple/slip ring arrangement. Experiments were performed for a range of liquid flow rates between 3.01pm and 15.01pm. The angular speed of the disk was varied from 0 rpm to 500 rpm. The local heat transfer coefficient was determined based on the heat flux supplied to the disk and the temperature difference between the measured disk surface temperature and the liquid entrance temperature onto the disk. The local heat transfer coefficient was seen to increase with increasing flow rate as well as increasing angular velocity of the disk. Effect of rotation on heat transfer was largest for the lower liquid flow rates with the effect gradually decreasing with increasing liquid flow rates. Semi-empirical correlations are presented in this study for the local and average Nusselt numbers.

  20. Flow injection method for the rapid determination of chemical oxygen demand based on microwave digestion and chromium speciation in flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Cuesta, A.; Todoli, J. L.; Canals, A.

    1996-12-01

    The present paper describes a new flow injection method for the determination of Chemical Oxygen Demand (COD). This method consists of a first digestion step, where the sample is heated by microwave radiation, a second one where an anionic exchange resin retains the Cr(VI) that has not been reduced by the organic matter of the sample and a third one where Cr(VI), after being eluted, is determined by flame atomic absorption spectrometry. The microwave power applied, the sulphuric acid concentration, the liquid flow in the digestion step and the sample volume were the variables studied. The recovery and precision obtained with this method are similar to those obtained using a standard semi-micro method, whereas the throughput is much higher (up to 50 determinations per hour). As regards sensitivity, by changing the sample loop volume and the concentration of dichromate, one can analyze samples with Chemical Oxygen Demand values between 25 and 5000 mg/l. The limit of detection is about 7 mg/l COD. An interesting feature of the new method, which is not shared by most other flow injection methods of Chemical Oxygen Demand determination, is that there is no matrix effect in the determination step.

  1. Liquid fuel spray processes in high-pressure gas flow

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1986-01-01

    Atomization of single liquid jets injected downstream in high pressure and high velocity airflow was investigated to determine the effect of airstream pressure on mean drop size as measured with a scanning radiometer. For aerodynamic - wave breakup of liquid jets, the ratio of orifice diameter D sub o to measured mean drop diameter D sub m which is assumed equal to D sub 32 or Sauter mean diameter, was correlated with the product of the Weber and Reynolds numbers WeRe and the dimensionless group G1/square root of c, where G is the gravitational acceleration, 1 the mean free molecular path, and square root of C the root mean square velocity, as follows; D sub o/D sub 32 = 1.2 (WeRe) to the 0.4 (G1/square root of c) to the 0.15 for values of WeRe 1 million and an airstream pressure range of 0.10 to 2.10 MPa.

  2. Liquid fuel spray processes in high-pressure gas flow

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1985-01-01

    Atomization of single liquid jets injected downstream in high pressure and high velocity airflow was investigated to determine the effect of airstream pressure on mean drop size as measured with a scanning radiometer. For aerodynamic - wave breakup of liquid jets, the ratio of orifice diameter D sub o to measured mean drop diameter D sub m which is assumed equal to D sub 32 or Sauter mean diameter, was correlated with the product of the Weber and Reynolds numbers WeRe and the dimensionless group G1/square root of c, where G is the gravitational acceleration, 1 the mean free molecular path, and square root of C the root mean square velocity, as follows; D sub o/D sub 32 = 1.2 (WeRe) to the 0.4 (G1/square root of c) to the 0.15 for values of WeRe 1 million and an airstream pressure range of 0.10 to 2.10 MPa.

  3. Nematic Director Reorientation at Solid and Liquid Interfaces under Flow: SAXS Studies in a Microfluidic Device

    PubMed Central

    2015-01-01

    In this work we investigate the interplay between flow and boundary condition effects on the orientation field of a thermotropic nematic liquid crystal under flow and confinement in a microfluidic device. Two types of experiments were performed using synchrotron small-angle X-ray-scattering (SAXS). In the first, a nematic liquid crystal flows through a square-channel cross section at varying flow rates, while the nematic director orientation projected onto the velocity/velocity gradient plane is measured using a 2D detector. At moderate-to-high flow rates, the nematic director is predominantly aligned in the flow direction, but with a small tilt angle of ∼±11° in the velocity gradient direction. The director tilt angle is constant throughout most of the channel width but switches sign when crossing the center of the channel, in agreement with the Ericksen–Leslie–Parodi (ELP) theory. At low flow rates, boundary conditions begin to dominate, and a flow profile resembling the escaped radial director configuration is observed, where the director is seen to vary more smoothly from the edges (with homeotropic alignment) to the center of the channel. In the second experiment, hydrodynamic focusing is employed to confine the nematic phase into a sheet of liquid sandwiched between two layers of Triton X-100 aqueous solutions. The average nematic director orientation shifts to some extent from the flow direction toward the liquid boundaries, although it remains unclear if one tilt angle is dominant through most of the nematic sheet (with abrupt jumps near the boundaries) or if the tilt angle varies smoothly between two extreme values (∼90 and 0°). The technique presented here could be applied to perform high-throughput measurements for assessing the influence of different surfactants on the orientation of nematic phases and may lead to further improvements in areas such as boundary lubrication and clarifying the nature of defect structures in LC displays. PMID

  4. Nematic director reorientation at solid and liquid interfaces under flow: SAXS studies in a microfluidic device.

    PubMed

    Silva, Bruno F B; Zepeda-Rosales, Miguel; Venkateswaran, Neeraja; Fletcher, Bretton J; Carter, Lester G; Matsui, Tsutomu; Weiss, Thomas M; Han, Jun; Li, Youli; Olsson, Ulf; Safinya, Cyrus R

    2015-04-14

    In this work we investigate the interplay between flow and boundary condition effects on the orientation field of a thermotropic nematic liquid crystal under flow and confinement in a microfluidic device. Two types of experiments were performed using synchrotron small-angle X-ray-scattering (SAXS). In the first, a nematic liquid crystal flows through a square-channel cross section at varying flow rates, while the nematic director orientation projected onto the velocity/velocity gradient plane is measured using a 2D detector. At moderate-to-high flow rates, the nematic director is predominantly aligned in the flow direction, but with a small tilt angle of ∼±11° in the velocity gradient direction. The director tilt angle is constant throughout most of the channel width but switches sign when crossing the center of the channel, in agreement with the Ericksen-Leslie-Parodi (ELP) theory. At low flow rates, boundary conditions begin to dominate, and a flow profile resembling the escaped radial director configuration is observed, where the director is seen to vary more smoothly from the edges (with homeotropic alignment) to the center of the channel. In the second experiment, hydrodynamic focusing is employed to confine the nematic phase into a sheet of liquid sandwiched between two layers of Triton X-100 aqueous solutions. The average nematic director orientation shifts to some extent from the flow direction toward the liquid boundaries, although it remains unclear if one tilt angle is dominant through most of the nematic sheet (with abrupt jumps near the boundaries) or if the tilt angle varies smoothly between two extreme values (∼90 and 0°). The technique presented here could be applied to perform high-throughput measurements for assessing the influence of different surfactants on the orientation of nematic phases and may lead to further improvements in areas such as boundary lubrication and clarifying the nature of defect structures in LC displays. PMID

  5. Dispersive liquid-liquid microextraction for the determination of copper in cereals and vegetable food samples using flame atomic absorption spectrometry.

    PubMed

    Shrivas, Kamlesh; Jaiswal, Nitin Kumar

    2013-12-01

    Dispersive liquid-liquid microextraction (DLLME) is applied for the determination of copper in cereals and vegetable food samples using flame atomic absorption spectrometry (FAAS). The maximum extraction efficiency of copper was obtained after the optimisation of parameters such as extraction and dispersing solvents, pH, concentration of 2,9-dimethyl-1,10-phenanothroline (DPT), N-phenylbenzimidoyl thiourea (PBITU) and salt. The optimised methodology exhibited a good linearity in the range of 0.2-20 ng/mL copper with relative standard deviations percentage (RSD,%) from ±1.5% to 3.5%. The method is found to be simple and rapid for the analysis of copper in food samples with the limit of detection (LOD) and quantitation (LOQ) were 0.05 and 0.16 ng/mL, respectively. Good recoveries of copper were obtained in the range of 93.5-98.0% in food samples as well as in Certified Reference Material (99.1%). The application of the proposed method has been successfully tested for the determination of copper in cereals (maize, millet, rice, wheat, gram, lentils, kidney beans and green beans) and vegetable (potato, cauliflower, tomato, spinach, green beans, lettuce, egg plants and bitter gourd) food samples. PMID:23870956

  6. Ligandless dispersive liquid--liquid microextraction of iron in biological and foodstuff samples and its determination by Electrothermal atomic absorption spectrometry.

    PubMed

    Madadizadeh, Mohadeseh; Taher, Mohammad Ali; Ashkenani, Hamid

    2013-01-01

    A new, simple, and efficient method comprising ligandless dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry is reported for the preconcentration and determination of ultratrace amounts of Fe(III). Carbon tetrachloride and acetone were used as the extraction and disperser solvents, respectively. Some effective parameters of the microextraction such as choice of extraction and disperser solvents, their volume, extraction time and temperature, salt and surfactant effect, and pH were optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.02 to 0.46 microg/L of Fe(III), with LOD and LOQ of 5.2 and 17.4 ng/L, respectively. The RSD for seven replicated determinations of Fe(IIl) ion at 0.1 microg/L concentration level was 5.2%. Operational simplicity, rapidity, low cost, good repeatability, and low consumption of extraction solvent are the main advantages of the proposed method. The method was successfully applied to the determination of iron in biological, food, and certified reference samples. PMID:24645530

  7. Determination of Lead in Water Samples Using a New Vortex-Assisted, Surfactant-Enhanced Emulsification Liquid-Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry.

    PubMed

    Peng, Guilong; He, Qiang; Lu, Ying; Mmereki, Daniel; Pan, Weiliang; Tang, Xiaohui; Zhou, Guangming; Mao, Yufeng; Su, Xaioxuan

    2016-04-01

    A low toxic solvent-based vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (LT-VSLLME) combined with graphite furnace atomic absorption spectrometry was developed for the extraction and determination of lead (Pb) in water samples. In the LT-VSLLME method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Meanwhile, the addition of a surfactant, which acted as an emulsifier, could enhance the speed of the mass-transfer from aqueous samples to the extraction solvent. The influences of analytical parameters, including extraction solvent type and its volume, surfactant type and its volume, pH, concentration of chelating agent, salt effect and extraction time were investigated. Under the optimized conditions, a good relative standard deviation of 3.69% at 10 ng L(-1) was obtained. The calibration graph showed a linear pattern in the ranges of 5-30 ngL(-1), with a limit of detection of 0.76 ng L(-1). The linearity was obtained by five points in the concentration range of 5-30 ngL(-1). The enrichment factor was 320. The procedure was applied to wastewater and river water, and the accuracy was assessed through the analysis of the recovery experiments. PMID:26614355

  8. Speciation of very low amounts of arsenic and antimony in waters using dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Rivas, Ricardo E.; López-García, Ignacio; Hernández-Córdoba, Manuel

    2009-04-01

    A new procedure for the determination of inorganic arsenic (III,V) and antimony (III,V) in water samples by dispersive liquid-liquid micro extraction separation and electrothermal atomic absorption spectrometry (ETAAS) is presented. At pH 1, As(III) and Sb(III) are complexed with ammonium pyrrolidine dithiocarbamate and extracted into the fine droplets formed when mixing carbon tetrachloride (extraction solvent), methanol (disperser solvent) and the sample solution. After extraction, the phases are separated by centrifugation, and As(III) and Sb(III) are determined in the organic phase. As(V) and Sb(V) remain in the aqueous layer. Total inorganic As and Sb are determined after the reduction of the pentavalent forms with sodium thiosulphate. As(V) and Sb(V) are calculated by difference. The detection limits are 0.01 and 0.05 µg L - 1 for As(III) and Sb(III), respectively, with an enrichment factor of 115. The relative standard deviation is in the 2.9-4.5% range. The procedure has been applied to the speciation of inorganic As and Sb in bottled, tap and sea water samples with satisfactory results.

  9. Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

    PubMed

    Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

    2010-06-30

    A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. PMID:20685458

  10. A dispersive liquid--liquid microextraction methodology for copper (II) in environmental samples prior to determination using microsample injection flame atomic absorption spectrometry.

    PubMed

    Alothman, Zeid A; Habila, Mohamed; Yilmaz, Erkan; Soylak, Mustafa

    2013-01-01

    A simple, environmentally friendly, and efficient dispersive liquid-liquid microextraction method combined with microsample injection flame atomic absorption spectrometry was developed for the separation and preconcentration of Cu(II). 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was used to form a hydrophobic complex of Cu(II) ions in the aqueous phase before extraction. To extract the Cu(II)-5-Br-PADAP complex from the aqueous phase to the organic phase, 2.0 mL of acetone as a disperser solvent and 200 microL of chloroform as an extraction solvent were used. The influences of important analytical parameters, such as the pH, types and volumes of the extraction and disperser solvents, amount of chelating agent, sample volume, and matrix effects, on the microextraction procedure were evaluated and optimized. Using the optimal conditions, the LOD, LOQ, preconcentration factor, and RSD were determined to be 1.4 microg/L, 4.7 microg/L, 120, and 6.5%, respectively. The accuracy of the proposed method was investigated using standard addition/recovery tests. The analysis of certified reference materials produced satisfactory analytical results. The developed method was applied for the determination of Cu in real samples. PMID:24645524

  11. Feasibility of dispersive liquid-liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M. M.; Duarte, Fabio A.

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid-liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L- 1 for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L- 1 and from 1.38 to 3.74 mg L- 1, respectively.

  12. Ultrasound-assisted ion-pair dispersive liquid-liquid microextraction of trace amounts of lead in water samples prior to graphite furnace atomic absorption spectrometry determination.

    PubMed

    Afzali, Daryoush; Mohadesi, Ali Reza; Falahnejad, Masoumeh; Bahadori, Behnoosh

    2013-01-01

    A new ion-pair dispersive liquid-liquid microextraction method is described for separation and preconcentration of trace amounts of lead in different water samples. Graphite furnace atomic absorption spectrometry was used for determination of lead. The ion association complex between lead and iodide ions that forms is PbI4(-2)-tetradecyl-dimethylbenzylammonium, which is extracted into fine droplets of chlorobenzene. In order to reach the optimized experimental conditions, the influence of different parameters, such as concentration of KI, nature and volume of extraction solvents, pH effect, extraction time, and the period and speed of sonication and centrifugation, were optimized. The LOD was 0.08 ng/mL and the linear dynamic range was 0.20-8.0 ng/mL in initial solution with a correlation coefficient of 0.9985. Under the optimum conditions, the enrichment factor was 555.5. The proposed method was successfully applied for separation and determination of lead in sea, rain, river, and drinking water samples. PMID:23513972

  13. Flow Characteristics of a Liquid Crystal Mixture in a Circular Pipe Electrode

    NASA Astrophysics Data System (ADS)

    Tsukiji, Tetsuhiro; Koyabu, Eitaro

    A circular pipe electrode was developed to control the pressure and the flow rate of the ER(Electro-rheological) fluids by one of the authors. The shape of the electrode is a circular pipe and some parts of the inner surface of the pipe are the electrode. The diameter of the tube is 1mm and the four pairs of the electrode are used. In the present study a liquid crystal mixture is selected for a homogeneous ER fluid and the pressure drop of the circular pipe electrode is measured for the constant flow rates under application of the voltages. The voltages are added in the peripheral direction. The director which is the average direction of the molecular of the liquid crystal is perpendicular to the flow direction. On the other hands, numerical analysis of the electric fields and the flow in the circular pipe electrode is conducted and the relations between the flow rate and the pressure are obtained for various electric field intensities, which almost agree with experimental results. The emphasized point of the present flow analysis is assuming that the viscosity of a liquid crystal mixture distributes in the flow field. Furthermore the pulse-wave voltages are added to the electrodes to control the pressure drop using the pulse width modulation. It is found that the pressure can be controlled using the pulse width modulation in the some range of the parameters.

  14. MHD Flow Of Walters' Liquid B Over A Nonlinearly Stretching Sheet

    NASA Astrophysics Data System (ADS)

    Siddheshwar, P. G.; Mahabaleshwar, U. S.; Chan, A.

    2015-08-01

    The paper discusses the boundary layer flow of a weak electrically conducting viscoelastic Walters' liquid B over a nonlinearly stretching sheet subjected to an applied transverse magnetic field, when the liquid far away from the surface is at rest. The stretching is assumed to be a quadratic function of the coordinate along the direction of stretching. An analytical expression is obtained for the stream function and velocity components as a function of the viscoelastic parameter, the Chandrasekhar number and stretching related parameters. The results have possible technological applications in liquid based systems involving stretchable materials.

  15. A 3D CFD simulation of liquid flow in an ironmaking blast furnace

    NASA Astrophysics Data System (ADS)

    Shen, Yansong; Guo, Baoyu; Chew, Sheng; Austin, Peter; Yu, Aibing

    2013-07-01

    A three-dimensional CFX-based mathematical model is developed to describe the flow-heat transfer-chemical reactions behaviours of gas-solid-liquid phases in an ironmaking blast furnace (BF), where the raceway cavity is considered explicitly. The typical in-furnace phenomena of an operating blast furnace, in particular, the liquid flow in the lower part of a blast furnace is simulated in aspects of velocity and volume fraction. This model offers a cost-effective tool to understand and optimize blast furnace operation.

  16. Evaluation of the viscosities of a liquid crystal model system by shear flow simulation

    NASA Astrophysics Data System (ADS)

    Sarman, Sten; Laaksonen, Aatto

    2009-09-01

    The three Miesowicz viscosities of a liquid crystal model system consisting of the Gay-Berne fluid have been obtained by shear flow simulations. The viscosities along an isochore have been followed starting in the nematic phase at high temperatures across the nematic-smectic A phase transition down to low temperatures in the smectic A phase. The relative magnitudes of the viscosities as a function of the structure of the liquid crystal are discussed. The viscosities obtained by the shear flow simulations agree very well with those obtained by Green-Kubo relations in a previous work.

  17. Electrical impedance imaging in two-phase, gas-liquid flows: 1. Initial investigation

    NASA Technical Reports Server (NTRS)

    Lin, J. T.; Ovacik, L.; Jones, O. C.

    1991-01-01

    The determination of interfacial area density in two-phase, gas-liquid flows is one of the major elements impeding significant development of predictive tools based on the two-fluid model. Currently, these models require coupling of liquid and vapor at interfaces using constitutive equations which do not exist in any but the most rudimentary form. Work described herein represents the first step towards the development of Electrical Impedance Computed Tomography (EICT) for nonintrusive determination of interfacial structure and evolution in such flows.

  18. Ultrasensitive determination of cadmium in seawater by hollow fiber supported liquid membrane extraction coupled with graphite furnace atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Peng, Jin-feng; Liu, Rui; Liu, Jing-fu; He, Bin; Hu, Xia-lin; Jiang, Gui-bin

    2007-05-01

    A new procedure, based on hollow fiber supported liquid membrane preconcentration coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection, was developed for the determination of trace Cd in seawater samples. With 1-octanol that contained a mixture of dithizone (carrier) and oleic acid immobilized in the pores of the polypropylene hollow fiber as a liquid membrane, Cd was selectively extracted from water samples into 0.05 M HNO 3 that filled the lumen of the hollow fiber as a stripping solution. The main extraction related parameters were optimized, and the effects of salinity and some coexisting interferants were also evaluated. Under the optimum extraction conditions, an enrichment factor of 387 was obtained for a 100-mL sample solution. In combination with graphite furnace atomic absorption spectrometry, a very low detection limit (0.8 ng L - 1 ) and a relative standard deviation (2.5% at 50 ng L - 1 level) were achieved. Five seawater samples were analyzed by the proposed method without dilution, with detected Cd concentration in the range of 56.4-264.8 ng L - 1 and the relative spiked recoveries over 89%. For comparison, these samples were also analyzed by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS) method after a 10-fold dilution for matrix effect elimination. Statistical analysis with a one-way ANOVA shows no significant differences (at 0.05 level) between the results obtained by the proposed and ICP-MS methods. Additionally, analysis of certified reference materials (GBW (E) 080040) shows good agreement with the certified value. These results indicate that this present method is very sensitive and reliable, and can effectively eliminate complex matrix interferences in seawater samples.

  19. Gas, liquids flow rates hefty at Galveston Bay discovery

    SciTech Connect

    Petzet, G.A.

    1998-01-19

    Extended flow tests indicate a large Vicksburg (Oligocene) gas, condensate, and oil field is about to be developed in western Galveston Bay. Internal estimates indicates that ultimate recovery from the fault block in which the discovery well was drilled could exceed 1 tcf of gas equivalent of proved, possible, and probable reserves. The paper discusses the test program for this field and other prospects in the Galveston Bay area.

  20. Impact of Gas-liquid Two-phase Flow on Fluid Borne Noise

    NASA Astrophysics Data System (ADS)

    Taniwaki, Mitsuhiro; Shimomura, Nobuo

    In pipe lines such as those found in refrigeration cycle, a gas-liquid two-phase flow may occur because of a pressure change in the pipe. This flow causes noise. A vapor phase ratio in a fluid and the behavior of bubbles are related to the outbreak of noise. This experimental study investigated the fluid borne noise caused by gas-liquid two-phase flow passing through a contracted section in horizontal pipe. In the experiment, sound pressure was measured for two purposes: to see the influence of the air-water ratio on sound pressure and to see the change in sound pressure when a single bubble passed through a contracted section in horizontal pipe. The experiment showed that the fluid borne noise of gas-liquid two-phase flow grew louder than that of a liquid single-phase flow. As for the frequency distribution of the fluid borne noise, the sound pressure level was higher in the high frequency band. Furthermore, the fluid borne noise grew louder with increasing bubble diameter.

  1. Research on Gas-liquid Flow Rate Optimization in Foam Drilling

    NASA Astrophysics Data System (ADS)

    Gao, B. K.; Sun, D. G.; Jia, Z. G.; Huang, Z. Q.

    2010-03-01

    With the advantages of less gas consumption, higher carrying rocks ability, lower leakage and higher penetration rate, foam drilling is widely used today in petroleum industry. In the process of foam underbalanced drilling, the mixture of gas, liquid and cuttings flows upwards through the annular, so it is a typical gas-liquid-solid multi-phase flow. In order to protect the reservoir and avoid borehole wall collapsing during foam drilling, it is crucial to ensure that the bottom hole pressure is lower than the formation pressure and higher than the formation collapse pressure, and in the mean time, foam drilling fluid in the whole wellbore should be in the best foam quality stage in order to have sufficient capacity to carry cuttings. In this paper, main relations between bottom hole pressure and gas-liquid injecting rate are analyzed with the underbalanced multiphase flow models. And in order to obtain precise flow pattern and flow pressure, the whole well bore is spatial meshed and iterative method is used. So, a convenient safety window expressed by gas-liquid injecting rate is obtained instead of that by bottom hole pressure. Finally, a foam drilling example from a block in Yemen is presented; the drilling results show that this method is reliable and practical.

  2. Liquid crystal coatings for surface shear stress visualization in hypersonic flows

    SciTech Connect

    Reda, D.C.; Aeschliman, D.P.

    1990-01-01

    Experiments were conducted to test the surface-shear-stress visualization capabilities of shear-stress-sensitive/temperature- insensitive liquid crystal compounds in hypersonic flow. Liquid crystal coatings were applied to the surface of a conical model, which was then exposed to a high-unit-Reynolds-number (2.3 {times} 10{sup 7}/m) Mach 5 flow. The coating was illuminated by white light, and its response to the various flow situations was monitored and recorded with standard video and high-speed movie cameras. Boundary layer transition to turbulence was clearly demarcated by the technique. The dynamic location of the transition front as a function of model angle of attack (for sharp and blunt cones, with and without boundary-layer trips) was recorded, and observations were found to be consistent with established (published) trends for hypersonic flows over conical bodies. Normal shock passage over the model during tunnel shutdown was recorded (at 400 frames/second), and the liquid crystal coating was observed to respond to this event in a time interval less than or equal to the time between sequential movie frame exposures ({le} 0.0025 seconds). The liquid crystal technique has thus been demonstrated as a viable diagnostic tool for use in transient/compressible flows. 18 refs., 3 figs.

  3. Study on solid-liquid two-phase unsteady flow characteristics with different flow rates in screw centrifugal pump

    NASA Astrophysics Data System (ADS)

    Li, R. N.; Y Wang, H.; Han, W.; Ma, W.; Shen, Z. J.

    2013-12-01

    The screw centrifugal pump is used as an object, and the unsteady numerical simulation of solid-liquid two-phase flow is carried out under different flow rate conditions in one circle by choosing the two-phase flow of sand and water as medium, using the software FLUENT based on the URANS equations, combining with sliding mesh method, and choosing the Mixture multiphase flow model and the SIMPLE algorithm. The results show that, with the flow rate increasing, the change trends for the pressure on volute outlet are almost constant, the fluctuation trends of the impeller axial force have a little change, the pressure and the axial force turn to decrease on the whole, the radial force gradually increases when the impeller maximum radius passes by half a cycle near the volute outlet, and the radial force gradually decreases when the maximum radius passes by the other half a cycle in a rotation cycle. The distributions of the solid particles are very uneven under a small flow rate condition on the face. The solid particles under a big flow rate condition are distributed more evenly than the ones under a small flow rate condition on the back. The theoretical basis and reference are provided for improving its working performance.

  4. Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

    NASA Astrophysics Data System (ADS)

    Masson, R.; Trenty, L.; Zhang, Y.

    2016-09-01

    This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov-Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the mass exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.

  5. A flow-through x-ray absorption spectroscopy cell for characterization of powder catalysts in the working state

    NASA Astrophysics Data System (ADS)

    Odzak, J. F.; Argo, A. M.; Lai, F. S.; Gates, B. C.; Pandya, K.; Feraria, L.

    2001-10-01

    We report the design and demonstration of an x-ray absorption spectroscopy (XAS) cell used for the characterization of solid (powder) catalysts in operation with gas-phase reactants. The use of powder samples removes complications arising from mass transfer limitations in pressed wafer samples, the typical form of catalyst used in other in situ XAS cells. The new cell allows collection of XAS data at temperatures ranging from about 230 to 470 K, gas flow rates ranging from about 10 to 500 ml min-1, and pressures ranging from about 1 to 3 atm. The cell is designed to function nearly as a plug flow reactor.

  6. Dual solutions of radiative MHD nanofluid flow over an exponentially stretching sheet with heat generation/absorption

    NASA Astrophysics Data System (ADS)

    Naramgari, Sandeep; Sulochana, C.

    2016-01-01

    In this study, we analyzed the heat and mass transfer in thermophoretic radiative hydromagnetic nanofluid flow over an exponentially stretching porous sheet embedded in porous medium with internal heat generation/absorption, viscous dissipation and suction/injection effects. The governing partial differential equations of the flow are converted into nonlinear coupled ordinary differential equations by using similarity transformation. Runge-Kutta-based shooting technique is employed to yield the numerical solutions for the model. The effect of non-dimensional parameters on velocity, temperature and concentration profiles are discussed and presented through graphs. The physical quantities of interest local skin friction coefficient, Nusselt and Sherwood numbers are calculated and presented through tables.

  7. Integrating sphere-based photoacoustic setup for simultaneous absorption coefficient and Grüneisen parameter measurements of biomedical liquids

    NASA Astrophysics Data System (ADS)

    Villanueva, Yolanda; Hondebrink, Erwin; Petersen, Wilma; Steenbergen, Wiendelt

    2015-03-01

    A method for simultaneously measuring the absorption coefficient μa and Grüneisen parameter Γ of biological absorbers in photoacoustics is designed and implemented using a coupled-integrating sphere system. A soft transparent tube with inner diameter of 0.58mm is used to mount the liquid absorbing sample horizontally through the cavity of two similar and adjacent integrating spheres. One sphere is used for measuring the sample's μa using a continuous halogen light source and a spectrometer fiber coupled to the input and output ports, respectively. The other sphere is used for simultaneous photoacoustic measurement of the sample's Γ using an incident pulsed light with wavelength of 750nm and a flat transducer with central frequency of 5MHz. Absolute optical energy and pressure measurements are not necessary. However, the derived equations for determining the sample's μa and Γ require calibration of the setup using aqueous ink dilutions. Initial measurements are done with biological samples relevant to biomedical imaging such as human whole blood, joint and cyst fluids. Absorption of joint and cyst fluids is enhanced using a contrast agent like aqueous indocyanine green dye solution. For blood sample, measured values of μa = 0.580 +/- 0.016 mm-1 and Γ = 0.166 +/- 0.006 are within the range of values reported in literature. Measurements with the absorbing joint and cyst fluid samples give Γ values close to 0.12, which is similar to that of water and plasma.

  8. Geometry of nematic liquid crystals under shearing flow

    NASA Astrophysics Data System (ADS)

    Simões, M.; Alves, F. S.; Palangana, A. J.

    2009-09-01

    In this work, an extended version of the Hess-Baalss conformal approach is used to propose a relation connecting the viscosity coefficients of the nematic liquid crystals. Starting from the well-known fact that, in its usual form, the conformal transformation leads to results which are not observed experimentally, it is shown that, when the director field of an ordered nematic phase under sheared motion is taken as a three-dimensional surface with torsion, the resulting theory describes the observed experimental data efficiently. Moreover, this model predicts that the five viscosity coefficients of the Leslie ah hoc model are not independent, but connected. A comparison of the deduced relationship with experimental data is performed and an excellent agreement is obtained.

  9. Pressure drop in fully developed, turbulent, liquid-vapor annular flows in zero gravity

    NASA Technical Reports Server (NTRS)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1992-01-01

    The prediction of frictional pressure drop in fully developed, turbulent, annular liquid-vapor flows in zero gravity using simulation experiments conducted on earth is described. The scheme extends the authors' earlier work on dispersed flows. The simulation experiments used two immiscible liquids of identical density, namely, water and n-butyl benzoate. Because of the lack of rigorous analytical models for turbulent, annular flows, the proposed scheme resorts to existing semiempirical correlations. Results based on two different correlations are presented and compared. Others may be used. It was shown that, for both dispersed and annular flow regimes, the predicted frictional pressure gradients in 0-g are lower than those in 1-g under otherwise identical conditions. The physical basis for this finding is given.

  10. High-accuracy measurement of low-water-content in liquid using NIR spectral absorption method

    NASA Astrophysics Data System (ADS)

    Peng, Bao-Jin; Wan, Xu; Jin, Hong-Zhen; Zhao, Yong; Mao, He-Fa

    2005-01-01

    Water content measurement technologies are very important for quality inspection of food, medicine products, chemical products and many other industry fields. In recent years, requests for accurate low-water-content measurement in liquid are more and more exigent, and great interests have been shown from the research and experimental work. With the development and advancement of modern production and control technologies, more accurate water content technology is needed. In this paper, a novel experimental setup based on near-infrared (NIR) spectral technology and fiber-optic sensor (OFS) is presented. It has a good measurement accuracy about -/+ 0.01%, which is better, to our knowledge, than most other methods published until now. It has a high measurement resolution of 0.001% in the measurement range from zero to 0.05% for water-in-alcohol measurement, and the water-in-oil measurement is carried out as well. In addition, the advantages of this method also include pollution-free to the measured liquid, fast measurement and so on.

  11. Two-colour micro-PIV and high speed shadowgraphy measurements for liquid-liquid plug flows

    NASA Astrophysics Data System (ADS)

    Chinaud, Maxime; Tsaoulidis, Dimitrios; Angeli, Panagiota Angeli; University College London Team; Memphis Collaboration

    2014-11-01

    Two-colour micro-Particle Image Velocimetry (micro-PIV) is a relatively new technique that provides velocity fields simultaneously in both phases of a two-phase flow system. In this work, a laser emitting at two different wavelengths was used to excite two different types of particles, each added in one of the liquid phases of a two-phase, oil-water, system. The two types of particles emitted signals at separate wavelengths that were captured simultaneously by two different cameras. Instantaneous velocity fields could thus be obtained in both phases at the same time. This technique was used to study liquid-liquid plug flows in microchannels. Both plug propagation in the main channel and plug formation in the T-shaped inlet junction have been investigated. During plug propagation analysis of the velocity fields reveals recirculation patterns inside the dispersed plug and the continuous slug. These will be related to dimensionless numbers. The results on plug formation will be discussed against current models on plug size. This work is undertaken as part of the UK Engineering and Physical Sciences Research Council Programme Grant MEMPHIS.

  12. Interfacial characteristics of stratified liquid-liquid flows using a conductance probe

    NASA Astrophysics Data System (ADS)

    Barral, A. H.; Angeli, P.

    2013-10-01

    In this paper, the characteristics of the interface in stratified oil-water flows and their changes during the transition to dual continuous flows were studied experimentally with a double-wire conductance probe. Experiments were carried out in an acrylic test section, 38 mm ID, using tap water and oil ( ρ = 830 kg m-3 and μ = 0.0055 kg m-1 s-1) as test fluids. The boundaries between stratified and dual continuous flow were identified from high-speed imaging. A double-wire conductance probe, consisting of two 0.5 mm wires set 2 mm apart along a vertical pipe diameter, was used to obtain time records of the interface height in stratified flow. The probe was located either close to the test section inlet or at 7 m downstream the inlet, where the flow was fully developed. Data were collected for a period of 4 min at 256 Hz sampling frequency. A rigorous methodology was followed to treat the probe data and to estimate average parameters such as interface height with known accuracy and confidence intervals. The analysis ensured repeatability of the results. The procedure allowed accurate estimations of the power spectra of the probe signal and revealed the characteristic frequencies of the interface in stratified flow. It was found that the transition from stratified to dual continuous flow delayed to higher mixture velocities at input oil-to-water flow rate ratios, r, close to 1. At 7 m from the inlet, where the flow is fully developed, the interface was found to be fluctuating with three-dimensional characteristics for all conditions studied, while the oil-to-water velocity ratios, calculated from interfacial heights, were close to 1. The power spectra of the probe data showed peaks at low frequencies (1-3 Hz) that were attributed to the pumps. A range of high frequency contributions (between 10 and 40 Hz) appeared as the mixture velocity increased, which reflect the fluctuating nature of the interface. The relative intensity of these contributions increased with

  13. Two-phase gas-liquid flow characteristics inside a plate heat exchanger

    SciTech Connect

    Nilpueng, Kitti; Wongwises, Somchai

    2010-11-15

    In the present study, the air-water two-phase flow characteristics including flow pattern and pressure drop inside a plate heat exchanger are experimentally investigated. A plate heat exchanger with single pass under the condition of counter flow is operated for the experiment. Three stainless steel commercial plates with a corrugated sinusoidal shape of unsymmetrical chevron angles of 55 and 10 are utilized for the pressure drop measurement. A transparent plate having the same configuration as the stainless steel plates is cast and used as a cover plate in order to observe the flow pattern inside the plate heat exchanger. The air-water mixture flow which is used as a cold stream is tested in vertical downward and upward flow. The results from the present experiment show that the annular-liquid bridge flow pattern appeared in both upward and downward flows. However, the bubbly flow pattern and the slug flow pattern are only found in upward flow and downward flow, respectively. The variation of the water and air velocity has a significant effect on the two-phase pressure drop. Based on the present data, a two-phase multiplier correlation is proposed for practical application. (author)

  14. Sintered plug flow modulation of a vapor-liquid phase separator for a helium II vessel

    NASA Technical Reports Server (NTRS)

    Frederking, T. H. K.; Chuang, C.; Kamioka, Y.; Lee, J. M.; Yuan, S. W. K.

    1984-01-01

    Presented is a system for modulation of a superfluid (helium II) flow in a vapor-liquid phase separator, for use in cryogenic storage tanks in future space missions. The system consists of a semicircular mechanically operated shutter, downstream of the separator plug, rotated at 0.1 rpm to control the operational surface area of the separator. The mass flow rate was varied from 10 to 22 mg/s. Pressure gradients across the plug are also discussed.

  15. Contactless flow measurement in liquid metal using electromagnetic time-of-flight method

    NASA Astrophysics Data System (ADS)

    Dubovikova, Nataliia; Resagk, Christian; Karcher, Christian; Kolesnikov, Yuri

    2016-05-01

    Measuring flow rates of liquid metal flows is of utmost importance in industrial applications such as metal casting, in order to ensure process efficiency and product quality. A non-contact method for flow rate control is described here. The method is known as time-of-flight Lorentz force velocimetry (LFV) and determines flow rate through measurement of Lorentz force that act on magnet systems that are placed close to the flow. In this method, a vortex generator is used to generate an eddy in the flow, with two magnet systems separated by a known distance placed downstream of the vortex generator. Each of the magnet systems has a force sensor attached to them which detects the passing of the eddy through its magnetic field as a significant perturbation in the force signal. The flow rate is estimated from the time span between the perturbations in the two force signals. In this paper, time-of-flight LFV technique is demonstrated experimentally for the case of liquid metal flow in a closed rectangular duct loop that is driven by an electromagnetic pump. A liquid metal alloy of gallium (Ga), indium (In) and tin (Sn)—GaInSn—is used as the working fluid. In contrast to prior works, for the first time, three-dimensional strain gauge force sensors were used for measuring Lorentz force to investigate the effect of flow disturbances in different directions for flow measurements by the time-of-flight LFV method. A prototype time-of-flight LFV flowmeter is developed, the operation of which in laboratory conditions is characterised by different experiments.

  16. Viscous Fingering Induced Flow Instability in Multidimensional Liquid Chromatography

    SciTech Connect

    Mayfield, Kirsty; Shalliker, R. Andrew; Catchpoole, Heather J.; Sweeney, Alan P.; Wong, Victor; Guiochon, Georges A

    2005-07-01

    Viscous fingering is a flow instability phenomenon that results in the destabilisation of the interface between two fluids of differing viscosities. The destabilised interface results in a complex mixing of the two fluids in a pattern that resembles fingers. The conditions that enhance this type of flow instability can be found in coupled chromatographic separation systems, even when the solvents used in each of the separation stages have seemingly similar chemical and physical properties (other than viscosity). For example, the viscosities of acetonitrile and methanol are sufficiently different that instability at the interface between these two solvents can be established and viscous fingering results. In coupled chromatographic systems, the volume of solvent transported from one separation dimension to the second often exceeds the injection volume by two or more orders of magnitude. As a consequence, viscous fingering may occur, when otherwise following the injection of normal analytical size injection plugs viscous fingering would not occur. The findings in this study illustrate the onset of viscous fingering in emulated coupled chromatographic systems and show the importance of correct solvent selection for optimum separation performance.

  17. The flow of a thin liquid film on a stationary and rotating disk. II - Theoretical prediction

    NASA Technical Reports Server (NTRS)

    Rahman, M. M.; Faghri, A.; Hankey, W. L.

    1990-01-01

    The existing theoretical models are improved and a systematic procedure to compute the free surface flow of a thin liquid film is suggested. The solutions for axisymmetric radial flow on a stationary horizontal disk and for the disk rotating around its axis are presented. The theoretical predictions are compared with the experimental data presented in Part I of this report. The analysis shows results for both supercritical and subcritical flows and the flow structure in the vicinity of a hydraulic jump which isolates these two flow types. The detailed flow structure in a hydraulic jump was computed and shown to contain regions of separation including a 'surface roller'. The effects of surface tension are found to be important near the outer edge of the disk where the fluid experiences a free fall. At other locations, the surface tension is negligible. For a rotating disk, the frictional resistance in the angular direction is found to be as important as that in the radial direction.

  18. Hollow fiber-based liquid-liquid-liquid microextraction followed by flow injection analysis using column-less HPLC for the determination of phenazopyridine in plasma and urine.

    PubMed

    Saraji, Mohammad; Bidgoli, Ali Akbar Hajialiakbari; Farajmand, Bahman

    2011-07-01

    Hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) followed by flow injection analysis and diode array detection (FIA-DAD) was applied as a simple and sensitive quantitative method for the determination of phenazopyridine in urine and plasma samples. Flow injection system included a conventional HPLC system (without a chromatographic column) and a diode array detector. The extraction of phenazopyridine was carried out using diphenyl ether as the organic phase for filling the pores of the hollow fiber wall, and 0.1 M H(2)SO(4) solution as acceptor phase in the lumen of the fiber. The factors affecting the HF-LLLME and flow injection analysis including type of organic solvent, pH of donor phase, extraction temperature, extraction time, stirring rate, and pH of mobile phase were investigated and the optimal extraction conditions were established. With the consumption of 5 mL of sample solution, the enrichment factor was about 230. The limit of detection was 0.5 μg/L with inter- and intra-day precision being (RSD%) 6.9 and 4.9, respectively. Excellent linearity was found between 5 and 200 μg/L. PMID:21681956

  19. Improvements to a Flow Sensor for Liquid Bismuth-Fed Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Bonds, Kevin; Polzin, Kurt A.

    2010-01-01

    Recently, there has been significant interest in using bismuth metal as a propellant in Hall Thrusters [1, 2]. Bismuth offers some considerable cost, weight, and space savings over the traditional propellant--xenon. Quantifying the performance of liquid metal-fed Hall thrusters requires a very precise measure of the low propellant flow rates [1, 2]. The low flow rates (10 mg/sec) and the temperature at which free flowing liquid bismuth exists (above 300 C) preclude the use of off-the-shelf flow sensing equipment [3]. Therefore a new type of sensor is required. The hotspot bismuth flow sensor, described in Refs. [1-5] is designed to perform a flow rate measurement by measuring the velocity at which a thermal feature moves through a flow chamber. The mass flow rate can be determined from the time of flight of the thermal peak, [4, 5]. Previous research and testing has been concerned mainly with the generation of the thermal peak and it's subsequent detection. In this paper, we present design improvements to the sensor concept; and the results of testing conducted to verify the functionality of these improvements. A ceramic material is required for the sensor body (see Fig. 1), which must allow for active heating of the bismuth flow channel to keep the propellant in a liquid state. The material must be compatible with bismuth and must be bonded to conductive elements to allow for conduction of current into the liquid metal and measurement of the temperature in the flow. The new sensor requires fabrication techniques that will allow for a very small diameter flow chamber, which is required to produce useful measurements. Testing of various materials has revealed several that are potentially compatible with liquid bismuth. Of primary concern in the fabrication and testing of a robust, working prototype, is the compatibility of the selected materials with one another. Specifically, the thermal expansion rates of the materials relative to the ceramic body cannot expand so

  20. Method for improving dissolution efficiency in gas-absorption and liquid extraction processes

    DOEpatents

    Kanak, Brant E.; Stephenson, Michael J.

    1981-01-01

    This invention is a method for improving dissolution efficiency in processes in which a feed fluid is introduced to a zone where it is contacted with a liquid solvent for preferentially removing a component of the feed and where part of the solvent so contacted undergoes transfer into the feed fluid to saturate the same. It has been found that such transfer significantly impairs dissolution efficiency. In accordance with the invention, an amount of the above-mentioned solvent is added to the feed fluid being introduced to the contact zone, the solvent being added in an amount sufficient to effect reduction or elimination of the above-mentioned transfer. Preferably, the solvent is added to the feed fluid in an amount saturating or supersaturating the feed fluid under the conditions prevailing in the contact zone.

  1. Acoustic wave absorption as a probe of dynamical geometrical response of fractional quantum Hall liquids

    NASA Astrophysics Data System (ADS)

    Yang, Kun

    2016-04-01

    We show that an acoustic crystalline wave gives rise to an effect similar to that of a gravitational wave to an electron gas. Applying this idea to a two-dimensional electron gas in the fractional quantum Hall regime, this allows for experimental study of its intra-Landau level dynamical response in the long-wavelength limit. To study such response we generalize Haldane's geometrical description of fractional quantum Hall states to situations where the external metric is time dependent. We show that such time-dependent metric (generated by acoustic wave) couples to collective modes of the system, including a quadrapolar mode at long wavelength, and magnetoroton at finite wavelength. Energies of these modes can be revealed in spectroscopic measurements, controlled by strain-induced Fermi velocity anisotropy. We argue that such geometrical probe provides a potentially highly useful alternative probe of quantum Hall liquids, in addition to the usual electromagnetic response.

  2. Method for improving dissolution efficiency in gas-absorption and liquid extraction processes. [Patent application

    DOEpatents

    Kanak, B.E.; Stephenson, M.J.

    1980-01-11

    A method is described for improving dissolution efficiency in processes in which a feed fluid is introduced to a zone where it is contacted with a liquid solvent for preferentially removing a component of the feed and where part of the solvent so contacted undergoes transfer into the feed fluid to saturate the same. It has been found that such transfer significantly impairs dissolution efficiency. In accordance with the invention, an amount of the above-mentioned solvent is added to the feed fluid being introduced to the contact zone, the solvent being added in an amount sufficient to effect reduction or elimination of the above-mentioned transfer. Preferably, the solvent is added to the feed fluid in an amount saturating or supersaturating the feed fluid under the conditions prevailing in the contact zone.

  3. Lattice Boltzmann simulation of asymmetric flow in nematic liquid crystals with finite anchoring

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Roberts, Tyler; Aranson, Igor S.; de Pablo, Juan J.

    2016-02-01

    Liquid crystals (LCs) display many of the flow characteristics of liquids but exhibit long range orientational order. In the nematic phase, the coupling of structure and flow leads to complex hydrodynamic effects that remain to be fully elucidated. Here, we consider the hydrodynamics of a nematic LC in a hybrid cell, where opposite walls have conflicting anchoring boundary conditions, and we employ a 3D lattice Boltzmann method to simulate the time-dependent flow patterns that can arise. Due to the symmetry breaking of the director field within the hybrid cell, we observe that at low to moderate shear rates, the volumetric flow rate under Couette and Poiseuille flows is different for opposite flow directions. At high shear rates, the director field may undergo a topological transition which leads to symmetric flows. By applying an oscillatory pressure gradient to the channel, a net volumetric flow rate is found to depend on the magnitude and frequency of the oscillation, as well as the anchoring strength. Taken together, our findings suggest several intriguing new applications for LCs in microfluidic devices.

  4. Lattice Boltzmann simulation of asymmetric flow in nematic liquid crystals with finite anchoring.

    PubMed

    Zhang, Rui; Roberts, Tyler; Aranson, Igor S; de Pablo, Juan J

    2016-02-28

    Liquid crystals (LCs) display many of the flow characteristics of liquids but exhibit long range orientational order. In the nematic phase, the coupling of structure and flow leads to complex hydrodynamic effects that remain to be fully elucidated. Here, we consider the hydrodynamics of a nematic LC in a hybrid cell, where opposite walls have conflicting anchoring boundary conditions, and we employ a 3D lattice Boltzmann method to simulate the time-dependent flow patterns that can arise. Due to the symmetry breaking of the director field within the hybrid cell, we observe that at low to moderate shear rates, the volumetric flow rate under Couette and Poiseuille flows is different for opposite flow directions. At high shear rates, the director field may undergo a topological transition which leads to symmetric flows. By applying an oscillatory pressure gradient to the channel, a net volumetric flow rate is found to depend on the magnitude and frequency of the oscillation, as well as the anchoring strength. Taken together, our findings suggest several intriguing new applications for LCs in microfluidic devices. PMID:26931724

  5. Modeling the liquid flow in up-flow anaerobic sludge blanket reactors

    SciTech Connect

    Bolle, W.L.; Van Breugel, J.; Van Eybergen, G.C.; Kossen, N.W.F.; Zoetemeyer, R.J.

    1986-11-01

    By means of stimulus-response experiments and Li+ tracer, models for the fluid flow in a 30-cubic m UASB reactor, used for the anaerobic treatment of wastewater, were tested. From the model with the best fit it could be derived that both the sludge bed and the sludge blanket can be described as perfectly mixed tank reactors with short-circuiting flows; the settler volume acts like a plug-flow region. Apart from the volumes of the different flow regions, two parameters are necessary and sufficient to describe the fluid flow in a well functioning UASB reactor, i.e., the short-circuiting flow over the sludge bed and the short-circuiting flow over the sludge blanket. The volumes could be measured accurately. The short-circuiting flow over the sludge bed is a linear function of the sludge bed height. When the optimal height of the sludge bed is defined as the height for which the short-ciruiting flows are as small as possible, a bed-height of 3.5-4 m is sufficient (for superficial gas velocities between 1 and 1.5 m/h). This is in contradiction to the results of other authors. The short-circuiting flows over the sludge bed and the sludge blanket were also influenced by the superficial gas velocity. 7 references.

  6. An investigation of the influence of acoustic waves on the liquid flow through a porous material

    NASA Astrophysics Data System (ADS)

    Poesio, Pietro; Ooms, Gijs; Barake, Sander; van der Bas, Fred

    2002-05-01

    An experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. Also, a temperature measurement of the flowing liquid inside the core was made. A high external pressure was applied in order to avoid cavitation. The acoustic waves were found to produce a significant effect on the pressure gradient at constant liquid flow rate through the core samples. During the application of acoustic waves the pressure gradient inside the core decreases. This effect turned out to be due to the decrease of the liquid viscosity caused by an increase in liquid temperature as a result of the acoustic energy dissipation inside the porous material. Also, a theoretical model has been developed to calculate the dissipation effect on the viscosity and on the pressure gradient. The model predictions are in reasonable agreement with the experimental data.

  7. An investigation of the influence of acoustic waves on the liquid flow through a porous material.

    PubMed

    Poesio, Pietro; Ooms, Gijs; Barake, Sander; van der Bas, Fred

    2002-05-01

    An experimental and theoretical investigation has been made of the influence of high-frequency acoustic waves on the flow of a liquid through a porous material. The experiments have been performed on Berea sandstone cores. Two acoustic horns were used with frequencies of 20 and 40 kHz, and with maximum power output of 2 and 0.7 kW, respectively. Also, a temperature measurement of the flowing liquid inside the core was made. A high external pressure was applied in order to avoid cavitation. The acoustic waves were found to produce a significant effect on the pressure gradient at constant liquid flow rate through the core samples. During the application of acoustic waves the pressure gradient inside the core decreases. This effect turned out to be due to the decrease of the liquid viscosity caused by an increase in liquid temperature as a result of the acoustic energy dissipation inside the porous material. Also, a theoretical model has been developed to calculate the dissipation effect on the viscosity and on the pressure gradient. The model predictions are in reasonable agreement with the experimental data. PMID:12051421

  8. Control of Flowing Liquid Films By Electrostatic Fields in Space

    NASA Technical Reports Server (NTRS)

    Bankoff, S. George; Miksis, Michael J.; Kim, Hyo

    1996-01-01

    A novel type of lightweight space radiator has been proposed which employs internal electrostatic fields to stop coolant leaks from punctures caused by micrometeorites or space debris. Extensive calculations have indicated the feasibility of leak stoppage without film destabilization for both stationary and rotating designs. Solutions of the evolution equation for a liquid-metal film on an inclined plate, using lubrication theory for low Reynolds numbers, Karman-Pohlhausen quadratic velocity profiles for higher Reynolds numbers, and a direct numerical solution are shown. For verification an earth-based falling-film experiment on a precisely-vertical wall with controllable vacuum on either side of a small puncture is proposed. The pressure difference required to start and to stop the leak, in the presence and absence of a strong electric field, will be measured and compared with calculations. Various parameters, such as field strength, film Reynolds number, contact angle, and hole diameter will be examined. A theoretical analysis will be made of the case where the electrode is close enough to the film surface that the electric field equation and the surface dynamics equations are coupled. Preflight design calculations will be made in order to transfer the modified equipment to a flight experiment.

  9. Combination of dispersive liquid-liquid microextraction with flame atomic absorption spectrometry using microsample introduction for determination of lead in water samples.

    PubMed

    Naseri, Mohammad Taghi; Hemmatkhah, Payam; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub

    2008-03-01

    The dispersive liquid-liquid microextraction (DLLME) was combined with the flame atomic absorption spectrometry (FAAS) for determination of lead in the water samples. Diethyldithiophosphoric acid (DDTP), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. A new FAAS sample introduction system was employed for the microvolume nebulization of the non-flammable chlorinated organic extracts. Injection of 20 microL volumes of the organic extract into an air-acetylene flame provided very sensitive spike-like and reproducible signals. Some effective parameters on the microextraction and the complex formation were selected and optimized. These parameters include extraction and disperser solvent type as well as their volume, extraction time, salt effect, pH and amount of the chelating agent. Under the optimized conditions, the enrichment factor of 450 was obtained from a sample volume of 25.0 mL. The enhancement factor, calculated as the ratio of the slopes of the calibration graphs with and without preconcentration, which was about 1000. The calibration graph was linear in the range of 1-70 microgL(-1) with a detection limit of 0.5 microgL(-1). The relative standard deviation (R.S.D.) for seven replicate measurements of 5.0 and 50 microgL(-1) of lead were 3.8 and 2.0%, respectively. The relative recoveries of lead in tap, well, river and seawater samples at the spiking level of 20 microgL(-1) ranged from 93.8 to 106.2%. The characteristics of the proposed method were compared with those of the liquid-liquid extraction (LLE), cloud point extraction (CPE), on-line and off-line solid-phase extraction (SPE) as well as co-precipitation, based on bibliographic data. Operation simplicity, rapidity, low cost, high enrichment factor, good repeatability, and low consumption of the extraction solvent at a microliter level are the main advantages of the proposed method. PMID:18267150

  10. Seismic scattering and absorption mapping of debris flows, feeding paths, and tectonic units at Mount St. Helens volcano

    NASA Astrophysics Data System (ADS)

    De Siena, Luca; Calvet, Marie; Watson, Keira J.; Jonkers, Art R. D.; Thomas, Christine

    2016-04-01

    Frequency-dependent peak-delay times and coda quality factors have been used jointly to separate seismic absorption from scattering quantitatively in Earth media at regional and lithospheric scale; to this end, we measure and map these two quantities at Mount St. Helens volcano. The results show that we can locate and characterise volcanic and geological structures using their unique contribution to seismic attenuation. At 3 Hz a single high-scattering and high-absorption anomaly outlines the debris flows that followed the 1980 explosive eruption, as deduced by comparison with remote sensing imagery. The flows overlay a NNW-SSE interface, separating rocks of significant varying properties down to 2-4 km, and coinciding with the Saint Helens Seismic Zone. High-scattering and high-absorption anomalies corresponding to known locations of magma emplacement follow this signature under the volcano, showing the important interconnections between its feeding systems and the regional tectonic boundaries. With frequency increasing from 6 to 18 Hz the NNW-SSE tectonic/feeding trends rotate around an axis centered on the volcano in the direction of the regional-scale magmatic arc (SW-NE). While the aseismic high-scattering region WSW of the volcano shows no evidence of high absorption, the regions of highest-scattering and absorption are consistently located at all frequencies under either the eastern or the south-eastern flank of the volcanic edifice. From the comparison with the available geological and geophysical information we infer that these anomalies mark both the location and the trend of the main feeding systems at depths greater than 4 km.

  11. Seismic scattering and absorption mapping of debris flows, feeding paths, and tectonic units at Mount St. Helens volcano

    NASA Astrophysics Data System (ADS)

    De Siena, L.; Calvet, M.; Watson, K. J.; Jonkers, A. R. T.; Thomas, C.

    2016-05-01

    Frequency-dependent peak-delay times and coda quality factors have been used jointly to separate seismic absorption from scattering quantitatively in Earth media at regional and continental scale; to this end, we measure and map these two quantities at Mount St. Helens volcano. The results show that we can locate and characterize volcanic and geological structures using their unique contribution to seismic attenuation. At 3 Hz a single high-scattering and high-absorption anomaly outlines the debris flows that followed the 1980 explosive eruption, as deduced by comparison with remote sensing imagery. The flows overlay a NNW-SSE interface, separating rocks of significant varying properties down to 2-4 km, and coinciding with the St. Helens Seismic Zone. High-scattering and high-absorption anomalies corresponding to known locations of magma emplacement follow this signature under the volcano, showing the important interconnections between its feeding systems and the regional tectonic boundaries. With frequency increasing from 6 to 18 Hz the NNW-SSE tectonic/feeding trends rotate around an axis centered on the volcano in the direction of the regional-scale magmatic arc (SW-NE). While the aseismic high-scattering region WSW of the volcano shows no evidence of high absorption, the regions of highest-scattering and absorption are consistently located at all frequencies under either the eastern or the south-eastern flank of the volcanic edifice. From the comparison with the available geological and geophysical information we infer that these anomalies mark both the location and the trend of the main feeding systems at depths greater than 4 km.

  12. Liquid-metal pin-fin pressure drop by correlation in cross flow

    SciTech Connect

    Wang, Zhibi; Kuzay, T.M.; Assoufid, L.

    1994-08-01

    The pin-fin configuration is widely used as a heat transfer enhancement method in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This paper investigates the pressure drop in a pin-post design beamline mirror with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in literature about pin-post mirrors or crystals is rare, and information about the pressure drop in pin-post mirrors with liquid metal as the coolant is even more sparse. Due to this the authors considered the cross flow in cylinder-array geometry, which is very similar to that of the pin-post, to examine the pressure drop correlation with liquid metals over pin fins. The cross flow of fluid with various fluid characteristics or properties through a tube bank was studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. Study lead to two major variables to influence the pressure drop: fluid properties, viscosity and density, and the relative length of the posts. Correlation of the pressure drop between long and short posts and the prediction of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed.

  13. Forced flow of a vapor-liquid stream in a horizontal pipe with film boiling

    NASA Astrophysics Data System (ADS)

    Kalinin, É. K.; Panevin, V. I.; Firsov, V. P.

    1986-05-01

    The stream structure and flow regime during film boiling of liquid nitrogen in a horizontal pipe are investigated. Data on heat transfer are obtained and a model is proposed for calculating the parameters of the two-phase stream along the channel length.

  14. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak.

    PubMed

    Ren, J; Zuo, G Z; Hu, J S; Sun, Z; Yang, Q X; Li, J G; Zakharov, L E; Xie, H; Chen, Z X

    2015-02-01

    A program involving the extensive and systematic use of lithium (Li) as a "first," or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak-both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST. PMID:25725839

  15. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Ren, J.; Zuo, G. Z.; Hu, J. S.; Sun, Z.; Yang, Q. X.; Li, J. G.; Xie, H.; Chen, Z. X.; Zakharov, L. E.

    2015-02-15

    A program involving the extensive and systematic use of lithium (Li) as a “first,” or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak—both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.

  16. Mathematical modelling of the liquid atomization process by cocurrent gas flow

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Boiko, V. M.; Goldin, V. D.; Maslov, E. A.; Orlov, S. E.; Poplavskiy, S. V.; Usanina, A. S.; Zharova, I. K.

    2016-04-01

    This paper focuses on the physical-mathematical model of liquid atomization in the spray pattern of an ejection nozzle. A flow field of a gas phase behind the nozzle section is computed using the Ansys Fluent package. Dynamics of molten metal droplets in the gas phase within a trajectory approach is calculated. Using the presented model, numerical calculation results are given.

  17. A flowing liquid lithium limiter for the Experimental Advanced Superconducting Tokamak

    NASA Astrophysics Data System (ADS)

    Ren, J.; Zuo, G. Z.; Hu, J. S.; Sun, Z.; Yang, Q. X.; Li, J. G.; Zakharov, L. E.; Xie, H.; Chen, Z. X.

    2015-02-01

    A program involving the extensive and systematic use of lithium (Li) as a "first," or plasma-facing, surface in Tokamak fusion research devices located at Institute of Plasma Physics, Chinese Academy of Sciences, was started in 2009. Many remarkable results have been obtained by the application of Li coatings in Experimental Advanced Superconducting Tokamak (EAST) and liquid Li limiters in the HT-7 Tokamak—both located at the institute. In furtherance of the lithium program, a flowing liquid lithium (FLiLi) limiter system has been designed and manufactured for EAST. The design of the FLiLi limiter is based on the concept of a thin flowing film which was previously tested in HT-7. Exploiting the capabilities of the existing material and plasma evaluation system on EAST, the limiter will be pre-wetted with Li and mechanically translated to the edge of EAST during plasma discharges. The limiter will employ a novel electro-magnetic pump which is designed to drive liquid Li flow from a collector at the bottom of limiter into a distributor at its top, and thus supply a continuously flowing liquid Li film to the wetted plasma-facing surface. This paper focuses on the major design elements of the FLiLi limiter. In addition, a simulation of incoming heat flux has shown that the distribution of heat flux on the limiter surface is acceptable for a future test of power extraction on EAST.

  18. Burnout and distribution of liquid between the flow core and wall films in narrow slot channels

    NASA Astrophysics Data System (ADS)

    Boltenko, E. A.; Shpakovskii, A. A.

    2010-03-01

    Previous works on studying distribution of liquid between the flow core and wall films in narrow slot channels are briefly reviewed. Interrelation between mass transfer processes and burnout is shown. A procedure for calculating burnout on convex and concave heat-transfer surfaces in narrow slot channels is presented.

  19. Removal of Salmonella enteritidis from unpasteurized liquid egg white using a cross flow microfiltration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Liquid egg white (LEW) is typically pasteurized to prevent common foodborne illnesses such as salmonellosis; however, heat pasteurization does not eliminate all pathogenic or spoilage microbes. In this study, a novel intervention technology based on cross-flow microfiltration (MF) was evaluated for ...

  20. LED-based UV absorption detector with low detection limits for capillary liquid chromatography.

    PubMed

    Sharma, Sonika; Tolley, H Dennis; Farnsworth, Paul B; Lee, Milton L

    2015-01-20

    A 260 nm deep UV LED-based absorption detector with low detection limits was developed and integrated with a small nanoflow pumping system. The detector is small in size (5.2 × 3.0 cm) and weighs only 85 g (without electronics). This detector was specifically designed and optimized for on-column detection to minimize extra-column band broadening. No optical reference was included due to the low drift in the signal. Two ball lenses, one of which was integrated with the LED, were used to increase light throughput through the capillary column. Stray light was minimized by the use of a band-pass filter and an adjustable slit. Signals down to the parts per billion level (nanomolar) were easily detected with a short-term noise level of 4.4 μAU, confirming a low limit of detection and low noise. The detection limit for adenosine-5'-monophosphate was 230 times lower than any previously reported values. Good linearities (3 orders of magnitude) were obtained using sodium anthraquinone-2-sulfonate, adenosine-5'-monophosphate, dl-tryptophan, and phenol. The LC system was demonstrated by performing isocratic separation of phenolic compounds using a monolithic capillary column (16.5 cm × 150 μm i.d.) synthesized from poly(ethylene glycol) diacrylate. PMID:25496031

  1. Drag reduction over liquid-infused surfaces in turbulent Taylor-Couette flow

    NASA Astrophysics Data System (ADS)

    van Buren, Tyler; Rosenberg, Brian; Smits, Alexander

    2015-11-01

    We present an experimental study on aqueous turbulent flow over a liquid-infused textured surface for the purpose of drag reduction. Taylor-Couette flow experiments are performed over a range of laminar to turbulent conditions (Re = 1500 to 7000), where the skin friction is compared to (i) a baseline case that consists of a textured surface with no impregnated fluid and (ii) an air-impregnated superhydrophic surface. We achieve drag reduction as high as 11% with superhydrophic surfaces and 4% with liquid infused surfaces. Of particular interest in this study is (1) the impact of surface texture shape and gap size on the resulting surface skin friction, (2) the importance of the viscosity ratios of the two fluids and its relationship to drag reduction, and (3) longevity of effectiveness when comparing liquid- to air-infused surfaces. This work was supported by the Office of Naval Research under MURI grant numbers: N000141210875, N000141210962, and N000141310458.

  2. Hydrodynamics of two-phase flow in gas-liquid cylindrical cyclone separators

    SciTech Connect

    Arpandi, I.; Joshi, A.R.; Shoham, O.

    1995-12-31

    This paper presents new experimental data and an improved mechanistic model for the Gas-Liquid Cylindrical Cyclone (GLCC) separator. The data were acquired utilizing a 3 inch ID laboratory-scale GLCC, and are presented along with a limited number of field data. The data include measurements of several parameters of the flow behavior and the operational envelope of the GLCC. The operational envelope defines the conditions for which there will be no liquid carry-over or gas carry-under. The developed model enables the prediction of the hydrodynamic flow behavior in the GLCC, including the operational envelope, equilibrium liquid level, vortex shape, velocity and holdup distributions and pressure drop across the GLCC. The predictions of the model are compared with the experimental data. These provide the state-of-the-art for the design of GLCC`s for the industry.

  3. Exploitation of pulsed flows for on-line dispersive liquid-liquid microextraction: Spectrophotometric determination of formaldehyde in milk.

    PubMed

    Nascimento, Carina F; Brasil, Marcos A S; Costa, Susana P F; Pinto, Paula C A G; Saraiva, Maria Lúcia M F S; Rocha, Fábio R P

    2015-11-01

    Formaldehyde is often added to foods as a preservative, but it is highly toxic to humans, having been identified as a carcinogenic substance. It has also been used for the adulteration of milk in order to diminish the bacteria count and increase the shelf life of the product. Herein, we present a green dispersive liquid-liquid microextraction procedure in a flow-batch system for the determination of formaldehyde in milk. Pulsed flows were exploited for the first time to improve the dispersion of the extractant in the aqueous phase. The Hantzsch reaction was used for the derivatization of formaldehyde and the product was extracted with the ionic liquid (IL) trihexyltetradecylphosphonium chloride with methanol as the disperser. The flow-batch chamber was made of stainless steel with the facility for resistive heating to speed up the derivatization reaction. Spectrophotometric measurements were directly carried out in the organic phase using an optical fiber spectrophotometer. The limit of detection and coefficient of variation were 100 μg L(-1) and 3.1% (n=10), respectively, with a linear response from 0.5 to 5.0 mg L(-1), described by the equation A=0.088+0.116CF (mg L(-1)) in which A is absorbance and CF is formaldehyde concentration in mg L(-1). The estimated recoveries of formaldehyde from spiked milk samples ranged from 91% to 106% and the slopes of the analytical curves obtained with reference solutions in water or milk were in agreement, thus indicating the absence of matrix effects. Accuracy was demonstrated by the agreement of the results with those achieved by the reference fluorimetric procedure at the 95% confidence level. The proposed procedure allows for 10 extractions per hour, with minimized reagent consumption (120 μL of IL and 3.5 μL acetylacetone) and generation of only 6.7 mL waste per determination, which contribute to the eco-friendliness of the procedure. PMID:26452946

  4. Interfacial-tension-force model for the wavy stratified liquid-liquid flow pattern transition: The usage of two different approaches

    NASA Astrophysics Data System (ADS)

    de Castro, Marcelo Souza; Rodriguez, Oscar Mauricio Hernandez

    2016-06-01

    The study of the hydrodynamic stability of flow patterns is important in the design of equipment and pipelines for multiphase flows. The maintenance of a particular flow pattern becomes important in many applications, e.g., stratified flow pattern in heavy oil production avoiding the formation of emulsions because of the separation of phases and annular flow pattern in heat exchangers which increases the heat transfer coefficient. Flow maps are drawn to orientate engineers which flow pattern is present in a pipeline, for example. The ways how these flow maps are drawn have changed from totally experimental work, to phenomenological models, and then to stability analysis theories. In this work an experimental liquid-liquid flow map, with water and viscous oil as work fluids, drawn via subjective approach with high speed camera was used to compare to approaches of the same theory: the interfacial-tension-force model. This theory was used to drawn the wavy stratified flow pattern transition boundary. This paper presents a comparison between the two approaches of the interfacial-tension-force model for transition boundaries of liquid-liquid flow patterns: (i) solving the wave equation for the wave speed and using average values for wave number and wave speed; and (ii) solving the same equation for the wave number and then using a correlation for the wave speed. The results show that the second approach presents better results.

  5. Potential transient liquid water flow features in fresh craters on Vesta

    NASA Astrophysics Data System (ADS)

    Scully, J. E.; Yin, A.; Russell, C. T.; Denevi, B. W.; Reddy, V.

    2012-12-01

    Observations made by the Dawn spacecraft reveal unexpected potential transient liquid water flow features (PTFs) in fresh craters on Vesta. The PTFs have features similar to the headward alcoves, channels and distal aprons of the Martian gullies and related features on Earth (e.g. Malin & Edgett 2000), and have been identified in multiple Vestan craters. All of the craters have relatively fresh rims, which suggests that they, and the PTFs, formed relatively recently in the history of Vesta's evolution. There is some correlation between craters that contain PTFs and craters that contain pitted terrain, which Denevi et al. (2012) propose formed as volatile-bearing material degassed after being heated by an impact. Cornelia crater contains good examples of PTFs and a geological map was made of Cornelia crater based on ~20 m/pixel resolution images. Cross-cutting relationships derived from the map make it is possible to discern a geological history: firstly, an early damp stage, during which the PTFs formed; secondly, a transitional damp to dry stage, during which the pitted terrain formed and thirdly, a dry stage. There is considerable morphological evidence that the formation of the PTFs in Cornelia was by flow of liquid water and not by dry granular flow, flow of impact melt or flow of liquid CO2. The channels are not as sinuous as those on the Earth and Mars, but the fact that the PTFs formed on the relatively high slopes of the crater walls and under conditions of Vesta's low gravity, means that the channels may not need to divert around obstacles. The PTFs in Cornelia crater tend to form in the dark material dominated areas of the crater, which Reddy et al. (2012) conclude has a composition similar to carbonaceous chondrite (CC) and think originates from the impactor that formed Vesta's Veneneia impact basin. Vesta's current surface temperatures and pressures make it an inhospitable environment for liquid water. But, energy from a high velocity impactor that

  6. Liquid metal magnetohydrodynamic flows in circular ducts at intermediate Hartmann numbers and interaction parameters

    NASA Astrophysics Data System (ADS)

    Molokov, S.; Reed, C. B.

    2003-12-01

    Magnetohydrodynamic flows in circular ducts in nonuniform magnetic fields are studied with reference to liquid metal blankets and divertors of fusion reactors. Flows in small and medium size reactors are characterized by moderate and low values of the Hartmann number (˜ 50-2000) and the interaction parameter (˜ 0.1-1000). The validity of the high-Hartmann number flow model for the intermediate range is discussed and the results of theoretical and experimental investigations are presented. Tables 2, Figs 5, Refs 8.

  7. Transport of Magnetic Field by a Turbulent Flow of Liquid Sodium

    SciTech Connect

    Volk, R.; Odier, Ph.; Pinton, J.-F.; Ravelet, F.; Monchaux, R.; Chiffaudel, A.; Daviaud, F.; Berhanu, M.; Fauve, S.; Mordant, N.; Petrelis, F.

    2006-08-18

    We study the effect of a turbulent flow of liquid sodium generated in the von Karman geometry, on the localized field of a magnet placed close to the frontier of the flow. We observe that the field can be transported by the flow on distances larger than its integral length scale. In the most turbulent configurations, the mean value of the field advected at large distance vanishes. However, the rms value of the fluctuations increases linearly with the magnetic Reynolds number. The advected field is strongly intermittent.

  8. Flow-assisted 2D polymorph selection: stabilizing metastable monolayers at the liquid-solid interface.

    PubMed

    Lee, Shern-Long; Yuan, Zhongyi; Chen, Long; Mali, Kunal S; Müllen, Klaus; De Feyter, Steven

    2014-05-28

    Controlling crystal polymorphism constitutes a formidable challenge in contemporary chemistry. Two-dimensional (2D) crystals often provide model systems to decipher the complications in 3D crystals. In this contribution, we explore a unique way of governing 2D polymorphism at the organic liquid-solid interface. We demonstrate that a directional solvent flow could be used to stabilize crystalline monolayers of a metastable polymorph. Furthermore, flow fields active within the applied flow generate millimeter-sized domains of either polymorph in a controlled and reproducible fashion. PMID:24867142

  9. Effects of gas flow on oxidation reaction in liquid induced by He/O{sub 2} plasma-jet irradiation

    SciTech Connect

    Nakajima, Atsushi; Uchida, Giichiro Takenaka, Kosuke; Setsuhara, Yuichi; Kawasaki, Toshiyuki; Koga, Kazunori; Sarinont, Thapanut; Amano, Takaaki; Shiratani, Masaharu

    2015-07-28

    We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.

  10. Effects of gas flow on oxidation reaction in liquid induced by He/O2 plasma-jet irradiation

    NASA Astrophysics Data System (ADS)

    Nakajima, Atsushi; Uchida, Giichiro; Kawasaki, Toshiyuki; Koga, Kazunori; Sarinont, Thapanut; Amano, Takaaki; Takenaka, Kosuke; Shiratani, Masaharu; Setsuhara, Yuichi

    2015-07-01

    We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much faster gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.

  11. Vortex-Shedding Meters For Liquid And Liquid/Gas Flows

    NASA Technical Reports Server (NTRS)

    Howard, Robert H.; Larson, William; Thinh, Ngo Dinh

    1993-01-01

    Flowmeters without moving parts developed as replacements for conventional turbine flowmeters. No maintenance required so meters installed permanently. In vortex-shedding flowmeter, piezoelectric or other suitable transducer probe senses changes of pressure caused by passage of vortices. Electronic circuitry processes pressure-change signals to extract vortex-passage frequency representing rate of flow.

  12. Liquid oil that flows in spaces of aqueous foam without defoaming.

    PubMed

    Sonoda, Junko; Sakai, Takaya; Inomata, Yukio

    2014-08-01

    A very interesting phenomenon has been observed in which foam formed from an aqueous fatty acid potassium salt solution spontaneously absorbs liquid oil immediately upon contact without defoaming. Although this phenomenon initially appeared to be based on capillary action, it was clarified that the liquid oil that flows in foam film did not wet the air/water interface. In this study, it is discussed why aqueous foam can spontaneously soak up liquid oil without defoaming using equilibrium surface tension, dynamic oil/water interfacial tension, and image analysis techniques. The penetration of oil was attributed both to the dynamic decrease in the surface tension at the oil/water interface and to Laplace pressure, depending on the curvature of the plateau border. Therefore, the foam does not absorb the oil, but the oil spontaneously penetrates the foam. This interesting behavior can be expected to be applied to aqueous detergents for liquid oil removal. PMID:25019527

  13. Immiscible liquid-liquid pressure-driven flow in capillary tubes: Experimental results and numerical comparison

    NASA Astrophysics Data System (ADS)

    Soares, Edson J.; Thompson, Roney L.; Niero, Debora C.

    2015-08-01

    The immiscible displacement of one viscous liquid by another in a capillary tube is experimentally and numerically analyzed in the low inertia regime with negligible buoyancy effects. The dimensionless numbers that govern the problem are the capillary number Ca and the viscosity ratio of the displaced to the displacing fluids Nμ. In general, there are two output quantities of interest. One is associated to the relation between the front velocity, Ub, and the mean velocity of the displaced fluid, U ¯ 2 . The other is the layer thickness of the displaced fluid that remains attached to the wall. We compute these quantities as mass fractions in order to make them able to be compared. In this connection, the efficiency mass fraction, me, is defined as the complement of the mass fraction of the displaced fluid that leaves the tube while the displacing fluid crosses its length. The geometric mass fraction, mg, is defined as the fraction of the volume of the layer that remains attached to the wall. Because in gas-liquid displacement, these two quantities coincide, it is not uncommon in the literature to use mg as a measure of the displacement efficiency for liquid-liquid displacements. However, as is shown in the present paper, these two quantities have opposite tendencies when we increase the viscosity of the displacing fluid, making this distinction a crucial aspect of the problem. Results from a Galerkin finite element approach are also presented in order to make a comparison. Experimental and numerical results show that while the displacement efficiency decreases, the geometrical fraction increases when the viscosity ratio decreases. This fact leads to different decisions depending on the quantity to be optimized. The quantitative agreement between the numerical and experimental results was not completely achieved, especially for intermediate values of Ca. The reasons for that are still under investigation. The experiments conducted were able to achieve a wide range

  14. The flow of a thin liquid film on a stationary and rotating disk. I - Experimental analysis and flow visualization

    NASA Technical Reports Server (NTRS)

    Thomas, S.; Faghri, A.; Hankey, W.

    1990-01-01

    The mean thickness of a thin liquid film of deionized water with a free surface on a stationary and rotating horizontal disk has been measured with a nonobtrusive capacitance technique. The measurements were taken when the rotational speed was 0-300 RPM and the flow rate was 7.0-15.0 LPM. A flow visualization study of the thin film was also performed to determine the characteristics of the waves on the free surface. When the disk was stationary, a circular hydraulic jump was present on the disk. Surface waves were found in the supercritical and subcritical regions at all flow rates studied. When the rotational speed of the disk is low, a standing wave at the edge of the disk was present. As the rotational speed increased, the surface waves changed from the wavy-laminar region to a region in which the waves ran nearly radially across the disk on top of a thin substrate of fluid.

  15. Non-Newtonian flow of an ultralow-melting chalcogenide liquid in strongly confined geometry

    SciTech Connect

    Wang, Siyuan; Jain, Chhavi; Wondraczek, Katrin; Kobelke, Jens; Wondraczek, Lothar; Troles, Johann; Caillaud, Celine; Schmidt, Markus A.

    2015-05-18

    The flow of high-viscosity liquids inside micrometer-size holes can be substantially different from the flow in the bulk, non-confined state of the same liquid. Such non-Newtonian behavior can be employed to generate structural anisotropy in the frozen-in liquid, i.e., in the glassy state. Here, we report on the observation of non-Newtonian flow of an ultralow melting chalcogenide glass inside a silica microcapillary, leading to a strong deviation of the shear viscosity from its value in the bulk material. In particular, we experimentally show that the viscosity is radius-dependent, which is a clear indication that the microscopic rearrangement of the glass network needs to be considered if the lateral confinement falls below a certain limit. The experiments have been conducted using pressure-assisted melt filling, which provides access to the rheological properties of high-viscosity melt flow under previously inaccessible experimental conditions. The resulting flow-induced structural anisotropy can pave the way towards integration of anisotropic glasses inside hybrid photonic waveguides.

  16. Visualizing mechanical stress and liquid flow during laser lithotripsy

    NASA Astrophysics Data System (ADS)

    Reinten, Ilja; Verdaasdonk, Rudolf; van der Veen, Albert; Klaessens, John

    2014-03-01

    The mechanism of action of the holmium laser lithotripsy is attributed to explosive expanding and imploding vapor bubbles in association with high-speed water jets creating high mechanical stress and cracking the stone surface. A good understanding of this mechanism will contribute to the improvement and the safety of clinical treatments. A new method has been developed to visualize the dynamics of mechanical effects and fluid flow induced by Holmium laser pulses around the fiber tip and the stone surface. The fiber tip was positioned near the surface of a stone on a slab of polyacrylamide gel submerged in water. The effects were captured with high speed imaging at 2000-10000 f/s. The dynamics of the pressure wave after the pulse could be visualized by observing the optical deformation of a fine line pattern in the background of the water container using digital subtraction software. This imaging technique provides a good understanding of the mechanical effects contributing to the effectiveness and safety of lithotripsy and can be used to study the optimal fiber shape and position towards the stone surface.

  17. Visual Measurements of Droplet Size in Gas Liquid Annular Flow

    SciTech Connect

    Fore, L.B.; Ibrahim, B.B.; Beus, S.G.

    2000-07-01

    Drop size distributions have been measured for nitrogen-water annular flow in a 9.67 mm hydraulic diameter duct, at system pressures of 3.4 and 17 atm and a temperature of 38 C. These new data extend the range of conditions represented by existing data in the open literature, primarily through an increase in system pressure. Since most existing correlations were developed from data obtained at lower pressures, it should be expected that the higher-pressure data presented in this paper would not necessarily follow those correlations. The correlation of Tatterson, et al. (1977) does not predict the new data very well, while the correlation of Kataoka, et al. (1983) only predicts those data taken at the lower pressure of 3.4 atm. However, the maximum drop size correlation of Kocamustafaogullari, et al. (1994) does predict the current data to a reasonable approximation. Similarly, their correlation for the Sauter mean diameter can predict the new data, provided the coefficient in the equation is adjusted.

  18. Short-range order in crystalline, amorphous, liquid, and supercooled germanium probed by x-ray-absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Filipponi, A.; di Cicco, A.

    1995-05-01

    A detailed experimental investigation of the short-range structural properties in condensed phases of germanium is presented. X-ray-absorption measurements at the Ge K edge have been collected in a wide temperature range for different samples. Polycrystalline c-Ge was measured at 77, 296, 450, 620, 782, 920, and 1110 K, close to the Ge melting-point temperature Tm=1210.4 K. Evaporated amorphous Ge was measured at 297 K. Eight independent measurements for liquid germanium have been collected from about 950 K in highly supercooled conditions up to about 1600 K. The spectra show a remarkable temperature trend. By comparison, previous diffraction measurements on l-Ge were limited to two narrow temperature regions only, either above Tm or around 1500 K, and no measurements in the supercooled liquid region existed. Data analysis has been performed with the GNXAS approach and account has been taken for the presence of double-excitation channels involving 3d and 3p electrons in addition to the 1s. The c-Ge structural results are found in excellent agreement with the known properties. The expansion of the average bond length R is in agreement with thermal expansion data. Mean-square vibrational amplitudes are in excellent agreement with both previous measurements and calculations in the harmonic approximation. The analysis of the signal in liquid Ge has been performed using a technique that allows to extract information on the radial distribution function g(r) directly comparable with molecular dynamics (MD) simulations or previous diffraction determinations. A regular trend is observed in the intensity of the first g(r) peak that decreases from 2.3 to 950 K to about 1.8 at 1610 K. At the same time a widening of the peak and a shift of the rising short distance edge is clearly detected. The data are in excellent agreement with diffraction measurements and recent ab initio MD results by Kresse and Hafner [Phys. Rev. B 49, 14 251 (1994)]. The general relevance of these

  19. Lagrangian approach to modeling unsteady gas-liquid flow in a well

    NASA Astrophysics Data System (ADS)

    Liapidevskii, V. Yu; Tikhonov, V.

    2016-06-01

    The purpose of this paper is to develop a numerical method of solving the problem of evolution of the finite gas volume that entered in a liquid flow at a set flow rate. The drift- flux model is used as gas-liquid mixture equations. The velocities of both phases, mixture and gas, are related by the Zuber-Findlay equation which coefficients depend on flow regime and gas void fraction. Lagrangian coordinates are used to simplify the initial equations. The numerical solution scheme is proposed. The numerical solution of the Riemann problem is verified by comparison with the exact self-similar solution. The model and numerical method efficiency is illustrated by examples of gas kick calculations in a vertical well.

  20. Numerical Simulation of MHD Effect in Liquid Metal Blankets with Flow Channel Insert

    NASA Astrophysics Data System (ADS)

    Mao, J.; Pan, H. C.

    2011-09-01

    The magnetohydrodynamic effect in liquid metal blankets with flow channel insert and pressure equalization slot for fusion liquid metal blanket is studied by numerical simulation based on two dimensional fully developed flow model. The code is verified by comparing analytical solution and numerical solution of Hunt Case II. The velocity field and MHD pressure drop varying with electric conductivity of the FCI is analyzed. The result shows that the average velocity in central area of the cross section decreases with the increase of the electric conductivity of FCI. While the average velocity in gap zone is reverse. Comparing with MHD duct flow without FCI, MHD pressure drop is reduced significantly when the FCI material is electrically insulating.