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Sample records for additional pressure drop

  1. Pressure Drop

    NASA Technical Reports Server (NTRS)

    Lawson, Mike

    2010-01-01

    Mike Lawson briefly discussed pressure drop for aerospace applications and presented short stories about adventures experienced while working at NASA and General Dynamics, including exposure to technologies like the Crew and Equipment Translation Aid (CETA) cart and the SWME.

  2. Gas Pressure-Drop Experiment

    ERIC Educational Resources Information Center

    Luyben, William L.; Tuzla, Kemal

    2010-01-01

    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  3. Pressure Drop in Radiator Air Tubes

    NASA Technical Reports Server (NTRS)

    Parsons, S R

    1921-01-01

    This report describes a method for measuring the drop in static pressure of air flowing through a radiator and shows (1) a reason for the discrepancy noted by various observers between head resistance and drop in pressure; (2) a difference in degree of contraction of the jet in entering a circular cell and a square cell; (3) the ratio of internal frictional resistance to total head resistance for two representative types; (4) the effect of smoothness of surface on pressure gradient; and (5) the effects of supplying heat to the radiator on pressure gradient. The fact that the pressure gradients are found to be approximately proportional to the square of the rate of flow of air appears to indicate turbulent flow, even in the short tubes of the radiator. It was found that the drop in the static pressure in the air stream through a cellular radiator and the pressure gradient in the air tubes are practically proportional to the square of the air flow in a given air density; that the difference between the head resistance per unit area and the fall of static pressure through the air tubes in radiators is apparent rather than real; and that radiators of different types differ widely in the amount of contraction of the jet at entrance. The frictional resistance was found to vary considerably, and in one case to be two-thirds of the head resistance in the type using circular cells and one-half of the head resistance of the radiator type using square cells of approximately the same dimensions.

  4. Predicting Pressure Drop In Porous Materials

    NASA Technical Reports Server (NTRS)

    Lawing, Pierce L.

    1990-01-01

    Theory developed to predict drop in pressure based on drag of individual fibers. Simple correlation method for data also developed. Helps in predicting flow characteristics of many strain-isolation pad (SIP) glow geometries in Shuttle Orbiter tile system. Also helps in predicting venting characteristics of tile assemblies during ascent and leakage of hot gas under tiles during descent. Useful in study of mechanics of flows through fibrous and porous media, and procedures applicable to purged fiberglass insulation, dialysis filters, and other fibrous and porous media.

  5. Routines for Computing Pressure Drops in Venturis

    NASA Technical Reports Server (NTRS)

    de Quay, Laurence

    2004-01-01

    A set of computer-program routines has been developed for calculating pressure drops and recoveries of flows through standard venturis, nozzle venturis, and orifices. Relative to prior methods used for such calculations, the method implemented by these routines offers greater accuracy because it involves fewer simplifying assumptions and is more generally applicable to wide ranges of flow conditions. These routines are based on conservation of momentum and energy equations for real nonideal fluids, the properties of which are calculated by curve-fitting subroutines based on empirical properties data. These routines are capable of representing cavitating, choked, non-cavitating, and unchoked flow conditions for liquids, gases, and supercritical fluids. For a computation of flow through a given venturi, nozzle venturi, or orifice, the routines determine which flow condition occurs: First, they calculate a throat pressure under the assumption that the flow is unchoked or non-cavitating, then they calculate the throat pressure under the assumption that the flow is choked or cavitating. The assumption that yields the higher throat pressure is selected as the correct one.

  6. Method for reducing pressure drop through filters, and filter exhibiting reduced pressure drop

    SciTech Connect

    Sappok, Alexander; Wong, Victor

    2014-11-18

    Methods for generating and applying coatings to filters with porous material in order to reduce large pressure drop increases as material accumulates in a filter, as well as the filter exhibiting reduced and/or more uniform pressure drop. The filter can be a diesel particulate trap for removing particulate matter such as soot from the exhaust of a diesel engine. Porous material such as ash is loaded on the surface of the substrate or filter walls, such as by coating, depositing, distributing or layering the porous material along the channel walls of the filter in an amount effective for minimizing or preventing depth filtration during use of the filter. Efficient filtration at acceptable flow rates is achieved.

  7. Preliminary Analysis of Liquid Metal MHD Pressure Drop in the Blanket for the FDS

    NASA Astrophysics Data System (ADS)

    Wang, Hong-yan; Wu, Yi-can; He, Xiao-xong

    2002-10-01

    Preliminary analysis and calculation of liquid metal Li17Pb83 magnetohydrodynamic (MHD) pressure drop in the blanket for the FDS have been presented to evaluate the significance of MHD effects on the thermal-hydraulic design of the blanket. To decrease the liquid metal MHD pressure drop, Al2O3 is applied as an electronically insulated coating onto the inner surface of the ducts. The requirement for the insulated coating to reduce the additional leakage pressure drop caused by coating imperfections has been analyzed. Finally, the total liquid metal MHD pressure drop and magnetic pump power in the FDS blanket have been given.

  8. Effect of humidity on the filter pressure drop

    SciTech Connect

    Vendel, J.; Letourneau, P.

    1995-02-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

  9. Pressure drop in tubing in aircraft instrument installations

    NASA Technical Reports Server (NTRS)

    Wildhack, W A

    1937-01-01

    The theoretical basis of calculation of pressure drop in tubing is reviewed briefly. The effect of pressure drop in connecting tubing upon the operation and indication of aircraft instruments is discussed. Approximate equations are developed, and charts and tables based upon them are presented for use in designing installations of altimeters, air-speed indicators, rate-of-climb indicators, and air-driven gyroscopic instruments.

  10. Determination of pressure drop coefficient by CFD simulation

    NASA Astrophysics Data System (ADS)

    Skočilasová, Blanka; Skočilas, Jan

    2014-08-01

    The article deals with method applied to the verification of the turbulence models. The turbulence models were used in the simulation of the Newtonian fluid turbulent flow in the circular tube. The principle of the method is in the comparison of the pressure drop obtained by the simulation and the analytic solution. The parameters of the fluid flow were varied with the specified Reynolds number range. The pressure drop of inserted element in the pipe is evaluated.

  11. The effect of pressure drop on respirator faceseal leakage.

    PubMed

    Janssen, Larry; Weber, Robert

    2005-07-01

    Users of particulate air-purifying respirators are typically told to change their filters when breathing resistance becomes uncomfortable. It has been proposed that a noticeable increase in breathing resistance (pressure drop) may increase airflow through respirator faceseal leaks. This logic has been extended to suggest that respirator user exposure to contaminants may increase because of this theoretical increase in air leakage. Procedures similar to those of previous investigators were used to study this issue. Repeated faceseal leak rate measurements were made at -5.6 through -20.1 mm water pressure drops across the faceseal. Subjects were divided into two groups, representing acceptable fit or unacceptable fit, based on leak rate criteria prescribed by the Occupational Safety and Health Administration (OSHA). Subjects with acceptable fit did not experience an increase in faceseal leak rate with increased pressure drop. Leak rates for subjects with unacceptable fit were highly variable and did not show an association with pressure drop. Results of this study do not support the concept of increased faceseal leakage with increased pressure drop. The evidence does not suggest increased risk of contaminant exposure through the face seal as pressure drop increases. PMID:16020096

  12. Low pressure drop airborne molecular contaminant filtration using open-channel networks

    NASA Astrophysics Data System (ADS)

    Dallas, Andrew J.; Ding, Lefei; Joriman, Jon; Zastera, Dustin; Seguin, Kevin; Empson, James

    2006-03-01

    Airborne molecular contamination (AMC) continues to play a very decisive role in the performance of many microelectronic devices and manufacturing processes. Currently, the state of the filtration industry is such that optimum filter life and removal efficiency for AMC is offered by granular filter beds. However, the attributes that make packed beds of adsorbents extremely efficient also impart issues related to elevated filter weight and pressure drop. Most of the low pressure drop AMC filters currently offered tend to be quiet costly and contaminant nonspecific. Many of these low pressure drop filters are simply pleated combinations of various adsorptive and reactive media. On the other hand, low pressure drop filters, such as those designed as open-channel networks (OCNs), can still offer good filter life and removal efficiency, with the additional benefits of significant reductions in overall filter weight and pressure drop. Equally important for many applications, the OCN filters can reconstruct the airflow so as to enhance the operation of a tool or process. For tool mount assemblies and full fan unit filters this can result in reduced fan and blower speeds, which subsequently can provide reduced vibration and energy costs. Additionally, these low pressure drop designs can provide a cost effective way of effectively removing AMC in full fab (or HVAC) filtration applications without significantly affecting air-handling requirements. Herein, we will present a new generation of low pressure drop OCN filters designed for AMC removal in a wide range of applications.

  13. System for Manipulating Drops and Bubbles Using Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    1999-01-01

    The manipulation and control of drops of liquid and gas bubbles is achieved using high intensity acoustics in the form of and/or acoustic radiation pressure and acoustic streaming. generated by a controlled wave emission from a transducer. Acoustic radiation pressure is used to deploy or dispense drops into a liquid or a gas or bubbles into a liquid at zero or near zero velocity from the discharge end of a needle such as a syringe needle. Acoustic streaming is useful in manipulating the drop or bubble during or after deployment. Deployment and discharge is achieved by focusing the acoustic radiation pressure on the discharge end of the needle, and passing the acoustic waves through the fluid in the needle. through the needle will itself, or coaxially through the fluid medium surrounding the needle. Alternatively, the acoustic waves can be counter-deployed by focusing on the discharge end of the needle from a transducer axially aligned with the needle, but at a position opposite the needle, to prevent premature deployment of the drop or bubble. The acoustic radiation pressure can also be used for detecting the presence or absence of a drop or a bubble at the tip of a needle or for sensing various physical characteristics of the drop or bubble such as size or density.

  14. Reducing cyclone pressure drop with evasés

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cyclones are widely used to separate particles from gas flows and as air emissions control devices. Their cost of operation is proportional to the fan energy required to overcome their pressure drop. Evasés or exit diffusers potentially could reduce exit pressure losses without affecting collection...

  15. Microseismicity Induced by Fluid Pressure Drop (Laboratory Study)

    NASA Astrophysics Data System (ADS)

    Turuntaev, Sergey; Zenchenko, Evgeny; Melchaeva, Olga

    2013-04-01

    Pore pressure change in saturated porous rocks may result in its fracturing (Maury et Fourmaintraux, 1993) and corresponding microseismic event occurrences. Microseismicity due to fluid injection is considered in numerous papers (Maxwell, 2010, Shapiro et al., 2005). Another type of the porous medium fracturing is related with rapid pore pressure drop at some boundary. The mechanism of such fracturing was considered by (Khristianovich, 1985) as a model of sudden coal blowing and by (Alidibirov, Panov, 1998) as a model of volcano eruptions. If the porous saturated medium has a boundary where it directly contacted with fluid under the high pressure (in a hydraulic fracture or in a borehole), and the pressure at that boundary is dropped, the conditions for tensile cracks can be achieved at some distance from the boundary. In the paper, the results of experimental study of saturated porous sample fracturing due to pore pressure rapid drop are discussed. The samples (82 mm high, ∅60 mm) were made of quartz sand, which was cemented by "liquid glass" glue with mass fraction 1%. The sample (porosity 35%, uniaxial unconfined compression strength 2.5 MPa) was placed in a mould and saturated by oil. The upper end of the sample contacted with the mould upper lid, the lower end contacted with fluid. The fluid pressure was increased to 10 MPa and then discharged through the bottom nipple. The pressure increases/drops were repeated 30-50 times. Pore pressure and acoustic emission (AE) were registered by transducers mounted into upper and bottom lids of the mould. It was found, that AE sources (corresponded to microfracturing) were spreading from the open end to the closed end of the sample, and that maximal number of AE events was registered at some distance from the opened end. The number of AE pulses increased with every next pressure drop, meanwhile the number of pulses with high amplitudes diminished. It was found that AE maximal rate corresponded to the fluid pressure

  16. Controlling Vapor Pressure In Hanging-Drop Crystallization

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C.; Smith, Robbie

    1988-01-01

    Rate of evaporation adjusted to produce larger crystals. Device helps to control vapor pressure of water and other solvents in vicinity of hanging drop of solution containing dissolved enzyme protein. Well of porous frit (sintered glass) holds solution in proximity to drop of solution containing protein or enzyme. Vapor from solution in frit controls evaporation of solvent from drop to control precipitation of protein or enzyme. With device, rate of nucleation limited to decrease number and increase size (and perhaps quality) of crystals - large crystals of higher quality needed for x-ray diffraction studies of macromolecules.

  17. Tetrasulfide extreme pressure lubricant additives

    SciTech Connect

    Gast, L.E.; Kenney, H.E.; Schwab, A.W.

    1980-08-19

    A novel class of compounds has been prepared comprising the tetrasulfides of /sup 18/C hydrocarbons, /sup 18/C fatty acids, and /sup 18/C fatty and alkyl and triglyceride esters. These tetrasulfides are useful as extreme pressure lubricant additives and show potential as replacements for sulfurized sperm whale oil.

  18. Experimental Investigation of Oscillatory Flow Pressure and Pressure Drop Through Complex Geometries

    NASA Technical Reports Server (NTRS)

    Ibrahim, Mounir B.; Wang, Meng; Gedeon, David

    2005-01-01

    A series of experiments have been performed to investigate the oscillatory flow pressure and pressure drop through complex geometries. These experiments were conducted at the CSU-SLRE facility which is a horizontally opposed, two-piston, single-acting engine with a split crankshaft driving mechanism. Flow through a rectangular duct, with no insert (obstruction), was studied first. Then four different inserts were examined: Abrupt, Manifold, Diverging Short and Diverging Long. The inserts were mounted in the center of the rectangular duct to represent different type of geometries that could be encountered in Stirling machines. The pressure and pressure drop of the oscillating flow was studied for: 1) different inserts, 2) different phase angle between the two pistons of the engine (zero, 90 lead, 180, and 90 lag), and 3) for different piston frequencies (5, 10, 15, and 20 Hz). It was found that the pressure drop of the oscillatory flow increases with increasing Reynolds number. The pressure drop was shown to be mainly due to the gas inertia for the case of oscillatory flow through a rectangular duct with no insert. On the other hand, for the cases with different inserts into the rectangular duct, the pressure drop has three sources: inertia, friction, and local losses. The friction pressure drop is only a small fraction of the total pressure drop. It was also shown that the dimensionless pressure drop decreases with increasing kinetic Reynolds number.

  19. PRESSURE DROP EVALUATION OF THE HYDROGEN CIRCULATION SYSTEM FOR JSNS

    SciTech Connect

    Tatsumoto, H.; Aso, T.; Ohtsu, K.; Kato, T.; Futakawa, M.

    2010-04-09

    In J-PARC, an intense spallation neutron source (JSNS) driven by a proton beam of 1 MW has selected supercritical hydrogen with a temperature of around 20 K and the pressure of 1.5 MPa as a moderator material. A hydrogen-circulation system, which consists of two pumps, an ortho-para hydrogen converter, a heater, an accumulator and a helium-hydrogen heat exchanger, has been designed to provide supercritical hydrogen to the moderators and remove the nuclear heating there. A hydrogen-circulation system is cooled through the heat exchanger by a helium refrigerator with the refrigeration power of 6.45 kW at 15.5 K. It is important for the cooling design of the hydrogen-circulation system to understand the pressure drops through the equipments. In this work, the pressure drop through each component was analyzed by using a CFD code, STAR-CD. The correlation of the pressure drops through the components that can describe the analytical results within 14% differences has been derived. It is confirmed that the pressure drop in the hydrogen circulation system would be estimated to be 37 kPa for the circulation flow rate of 160 g/s by using the correlations derived here, and is sufficiently lower than the allowable pump head of 100 kPa.

  20. Pressure Drop Evaluation of the Hydrogen Circulation System for Jsns

    NASA Astrophysics Data System (ADS)

    Tatsumoto, H.; Aso, T.; Ohtsu, K.; Kato, T.; Futakawa, M.

    2010-04-01

    In J-PARC, an intense spallation neutron source (JSNS) driven by a proton beam of 1 MW has selected supercritical hydrogen with a temperature of around 20 K and the pressure of 1.5 MPa as a moderator material. A hydrogen-circulation system, which consists of two pumps, an ortho-para hydrogen converter, a heater, an accumulator and a helium-hydrogen heat exchanger, has been designed to provide supercritical hydrogen to the moderators and remove the nuclear heating there. A hydrogen-circulation system is cooled through the heat exchanger by a helium refrigerator with the refrigeration power of 6.45 kW at 15.5 K. It is important for the cooling design of the hydrogen-circulation system to understand the pressure drops through the equipments. In this work, the pressure drop through each component was analyzed by using a CFD code, STAR-CD. The correlation of the pressure drops through the components that can describe the analytical results within 14% differences has been derived. It is confirmed that the pressure drop in the hydrogen circulation system would be estimated to be 37 kPa for the circulation flow rate of 160 g/s by using the correlations derived here, and is sufficiently lower than the allowable pump head of 100 kPa.

  1. PRESSURE DROP REDUCTION BY ELECTRICAL ENHANCEMENT OF FABRIC FILTRATION

    EPA Science Inventory

    The paper discusses economic studies of electrostatic augmentation of fabric filtration (ESFF) that indicate that the reduced rate of pressure drop rise can lead to lower capital and operating costs. (ESFF has been evaluated in the laboratory and at various pilot scales over the ...

  2. Validation of an All-Pressure Fluid Drop Model: Heptane Fluid Drops in Nitrogen

    NASA Technical Reports Server (NTRS)

    Harstad, K.; Bellan, J.; Bulzan, Daniel L. (Technical Monitor)

    2000-01-01

    Despite the fact that supercritical fluids occur both in nature and in industrial situations, the fundamentals of their behavior is poorly understood because supercritical fluids combine the characteristics of both liquids and gases, and therefore their behavior is not intuitive. There are several specific reasons for the lack of understanding: First, data from (mostly optical) measurements can be very misleading because regions of high density thus observed are frequently identified with liquids. A common misconception is that if in an experiment one can optically identify "drops" and "ligaments", the observed fluid must be in a liquid state. This inference is incorrect because in fact optical measurements detect any large change (i.e. gradients) in density. Thus, the density ratio may be well below Omicron(10(exp 3)) that characterizes its liquid/gas value, but the measurement will still identify a change in the index of refraction providing that the change is sudden (steep gradients). As shown by simulations of supercritical fluids, under certain conditions the density gradients may remain large during the supercritical binary fluids mixing, thus making them optically identifiable. Therefore, there is no inconsistency between the optical observation of high density regions and the fluids being in a supercritical state. A second misconception is that because a fluid has a liquid-like density, it is appropriate to model it as a liquid. However, such fluids may have liquid-like densities while their transport properties differ from those of a liquid. Considering that the critical pressure of most fuel hydrocarbons used in Diesel and gas turbine engines is in the range of 1.5 - 3 MPa, and the fact that the maximum pressure attained in these engines is about 6 Mps, it is clear that the fuel in the combustion chamber will experience both subcritical and supercritical conditions. Studies of drop behavior over a wide range of pressures were performed in the past

  3. Experimental investigation of ice slurry flow pressure drop in horizontal tubes

    SciTech Connect

    Grozdek, Marino; Khodabandeh, Rahmatollah; Lundqvist, Per

    2009-01-15

    Pressure drop behaviour of ice slurry based on ethanol-water mixture in circular horizontal tubes has been experimentally investigated. The secondary fluid was prepared by mixing ethyl alcohol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 C). The pressure drop tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 30% depending on test conditions. Results from flow tests reveal much higher pressure drop for higher ice concentrations and higher velocities in comparison to the single phase flow. However for ice concentrations of 15% and higher, certain velocity exists at which ice slurry pressure drop is same or even lower than for single phase flow. It seems that higher ice concentration delay flow pattern transition moment (from laminar to turbulent) toward higher velocities. In addition experimental results for pressure drop were compared to the analytical results, based on Poiseulle and Buckingham-Reiner models for laminar flow, Blasius, Darby and Melson, Dodge and Metzner, Steffe and Tomita for turbulent region and general correlation of Kitanovski which is valid for both flow regimes. For laminar flow and low buoyancy numbers Buckingham-Reiner method gives good agreement with experimental results while for turbulent flow best fit is provided with Dodge-Metzner and Tomita methods. Furthermore, for transport purposes it has been shown that ice mass fraction of 20% offers best ratio of ice slurry transport capability and required pumping power. (author)

  4. Low pressure drop filtration of airborne molecular organic contaminants using open-channel networks

    NASA Astrophysics Data System (ADS)

    Dallas, Andrew J.; Joriman, Jon; Ding, Lefei; Weineck, Gerald; Seguin, Kevin

    2007-03-01

    Airborne molecular contamination (AMC) continues to play a very decisive role in the performance of many microelectronic devices and manufacturing processes. Besides airborne acids and bases, airborne organic contaminants such as 1-methyl-2-pyrrolidinone (NMP), hexamethyldisiloxane (HMDSO), trimethylsilanol (TMS), perfluoroalkylamines and condensables are of primary concern in these applications. Currently, the state of the filtration industry is such that optimum filter life and removal efficiency for organics is offered by granular carbon filter beds. However, the attributes that make packed beds of activated carbon extremely efficient also impart issues related to elevated filter weight and pressure drop. Most of the lower pressure drop AMC filters currently offered are quite expensive and are simply pleated combinations of various adsorptive and reactive media. On the other hand, low pressure drop filters, such as those designed as open-channel networks (OCN's), offer good filter life and removal efficiency with the additional benefits of significant reductions in overall filter weight and pressure drop. Equally important for many applications, the OCN filters can reconstruct the airflow so as to enhance the operation of a tool or process. For tool mount assemblies and fan filter units (FFUs) this can result in reduced fan and blower speeds, which subsequently can provide reduced vibration and energy costs. Additionally, these low pressure drop designs can provide a cost effective way of effectively removing AMC in full fab (or HVAC) filtration applications without significantly affecting air-handling requirements. Herein, we will present a new generation of low pressure drop OCN filters designed for the removal of airborne organics in a wide range of applications.

  5. Air Flow and Pressure Drop Measurements Across Porous Oxides

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus air flow is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected flow decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of air flow versus processing parameters and the resulting porosity size and distribution.

  6. Numerical Analysis including Pressure Drop in Oscillating Water Column Device

    NASA Astrophysics Data System (ADS)

    das Neves Gomes, Mateus; Domingues dos Santos, Elizaldo; Isoldi, Liércio André; Rocha, Luiz Alberto Oliveira

    2015-06-01

    The wave energy conversion into electricity has been increasingly studied in the last years. There are several proposed converters. Among them, the oscillatingwater column (OWC) device has been widespread evaluated in literature. In this context, the main goal of this work was to perform a comparison between two kinds of physical constraints in the chimney of the OWC device, aiming to represent numerically the pressure drop imposed by the turbine on the air flow inside the OWC. To do so, the conservation equations of mass,momentumand one equation for the transport of volumetric fraction were solved with the finite volume method (FVM). To tackle thewater-air interaction, the multiphase model volume of fluid (VOF)was used. Initially, an asymmetric constraint inserted in chimney duct was reproduced and investigated. Subsequently, a second strategywas proposed,where a symmetric physical constraint with an elliptical shapewas analyzed. Itwas thus possible to establish a strategy to reproduce the pressure drop in OWC devices caused by the presence of the turbine, as well as to generate its characteristic curve.

  7. Pressure drop and heat transfer in inverted film boiling hydrogen

    NASA Astrophysics Data System (ADS)

    Pasch, James

    Two-phase boiling hydrogen pressure drop and heat transfer is studied in the context of high velocity upflow in a constant, high heat flux, steady state, internal pipe flow environment. These data were generated by NASA in the early and mid 1960s in support of the manned space flight programs. Measurements taken were local pressure, temperature, and voltage drop. System measurements included mass flow rate, and test section inlet and discharge pressure and temperature. This effort establishes the nature of the flow as inverted film boiling, which has been studied to some degree. In this structure, the wall temperatures are too hot to allow liquid to remain at the surface. Therefore, a vapor film is established at the wall throughout the flow. The approach of this analysis is to reverse-engineer the data to determine mass quality, void fraction, and velocity slip. This is accomplished by applying a one-dimensional, five-equation model, with pressure gradient being the one combined equation for the liquid and vapor phases. Other major assumptions are that all of the vapor is at the mean film temperature, and the liquid core experiences no sensible heating. The resulting velocity slips are correlated for high and low pressure conditions, with the cutoff established at 600 kPa. Good agreement is achieved between the pressures predicted using the slip correlations and the measured pressures. Results are in general significantly better than those from the homogeneous equilibrium model. Various established heat transfer coefficient models are also applied to these data. It is shown that pre-critical heat flux models fail absolutely to predict the heat transfer coefficient. It is further shown that film boiling models that focus on buoyancy fail as well. While all forced convection film boiling models are within a reasonable range of the data, recommendations for appropriate models are made. The range of pipe inlet conditions are 188 kPa to 1265 kPa, mass fluxes from 327

  8. Blood Pressure Drop Prediction by using HRV Measurements in Orthostatic Hypotension.

    PubMed

    Sannino, Giovanna; Melillo, Paolo; Stranges, Saverio; De Pietro, Giuseppe; Pecchia, Leandro

    2015-11-01

    Orthostatic Hypotension is defined as a reduction of systolic and diastolic blood pressure within 3 minutes of standing, and may cause dizziness and loss of balance. Orthostatic Hypotension has been considered an important risk factor for falls since 1960. This paper presents a model to predict the systolic blood pressure drop due to orthostatic hypotension, relying on heart rate variability measurements extracted from 5 minute ECGs recorded before standing. This model was developed and validated with the leave-one-out cross-validation technique involving 10 healthy subjects, and finally tested with an additional 5 healthy subjects, whose data were not used during the training and cross-validation process. The results show that the model predicts correctly the systolic blood pressure drop in 80 % of all experiments, with an error rate below the measurement error of a sphygmomanometer digital device. PMID:26345451

  9. Pressure drop of He II flow through a porous media

    NASA Technical Reports Server (NTRS)

    Maddocks, J. R.; Van Sciver, S. W.

    1990-01-01

    The paper reports on measurements of He II pressure drop across two porous SiO2 ceramic filter materials. These materials vary only in porosity, having values of 0.94 and 0.96. The average fiber diameter in both cases is approximately 5 microns. The experiment consists of a glass tube containing a piece of this sponge in one end. The tube is rapidly displaced downward in a bath of helium and the liquid levels are allowed to equilibrate over time producing variable velocities up to 10 cm/sec. The results are compared with those previously obtained using fine mesh screens. Good qualitative agreement is observed for turbulent flow; however, the behavior in the laminar flow regime is not fully understood.

  10. Decrease in Corneal Damage due to Benzalkonium Chloride by the Addition of Mannitol into Timolol Maleate Eye Drops.

    PubMed

    Nagai, Noriaki; Yoshioka, Chiaki; Tanino, Tadatoshi; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

    2015-01-01

    We investigated the protective effects of mannitol on corneal damage caused by benzalkonium chloride (BAC), which is used as a preservative in commercially available timolol maleate eye drops, using rat debrided corneal epithelium and a human cornea epithelial cell line (HCE-T). Corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera; eye drops were instilled into rat eyes five times a day after corneal epithelial abrasion. The viability of HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the eye drops were determined using rabbits. The corneal wound healing rate and rate constant (kH), as well as cell viability, were higher following treatment with 0.005% BAC solution containing 0.5% mannitol than in the case BAC solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without mannitol. In addition, the kH for rat eyes instilled with commercially available timolol maleate eye drops containing 0.5% mannitol was significantly higher than that for eyes instilled with timolol maleate eye drops without mannitol, and the addition of mannitol did not affect the corneal penetration or IOP reducing effect of the timolol maleate eye drops. A preservative system comprising BAC and mannitol may provide effective therapy for glaucoma patients requiring long-term treatment with anti-glaucoma agents. PMID:26136174

  11. Decrease in corneal damage due to benzalkonium chloride by the addition of sericin into timolol maleate eye drops.

    PubMed

    Nagai, Noriaki; Ito, Yoshimasa; Okamoto, Norio; Shimomura, Yoshikazu

    2013-01-01

    We investigated the protective effects of sericin on corneal damage due to benzalkonium chloride (BAC) used as a preservative in commercially available timolol maleate eye drops using rat debrided corneal epithelium and a human cornea epithelial cell line (HCE-T). Corneal wounds were monitored using a fundus camera TRC-50X equipped with a digital camera; eye drops were instilled into the rat eyes five times a day after corneal epithelial abrasion. The viability of HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the eye drops were determined using rabbits. The corneal wound healing rate and rate constants (kH) as well as cell viability were higher following treatment with 0.005% BAC solution containing 0.1% sericin than in the case of treatment with BAC solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without sericin. In addition, the kH for rat eyes instilled with commercially available timolol maleate eye drops containing 0.1% sericin was significantly higher than that of eyes instilled with timolol maleate eye drops without sericin, and the addition of sericin did not affect the corneal penetration or IOP reducing effect of commercially available timolol maleate eye drops. A preservative system comprising BAC and sericin may provide effective therapy for glaucoma patients requiring long-term anti-glaucoma agents. PMID:23470443

  12. Pressure drop and thrust predictions for transonic micronozzle flows

    NASA Astrophysics Data System (ADS)

    Gomez, J.; Groll, R.

    2016-02-01

    In this paper, the expansion of xenon, argon, krypton, and neon gases through a Laval nozzle is studied experimentally and numerically. The pressurized gases are accelerated through the nozzle into a vacuum chamber in an attempt to simulate the operating conditions of a cold-gas thruster for attitude control of a micro-satellite. The gases are evaluated at several mass flow rates ranging between 0.178 mg/s and 3.568 mg/s. The Re numbers are low (8-256) and the estimated values of Kn number lie between 0.33 and 0.02 (transition and slip-flow regime). Direct Simulation Monte Carlo (DSMC) and continuum-based simulations with a no-slip boundary condition are performed. The DSMC and the experimental results show good agreement in the range Kn > 0.1, while the Navier-Stokes results describe the experimental data more accurately for Kn < 0.05. Comparison between the experimental and Navier-Stokes results shows high deviations at the lower mass flow rates and higher Kn numbers. A relation describing the deviation of the pressure drop through the nozzle as a function of Kn is obtained. For gases with small collision cross sections, the experimental pressure results deviate more strongly from the no-slip assumption. From the analysis of the developed function, it is possible to correct the pressure results for the studied gases, both in the slip-flow and transition regimes, with four gas-independent accommodation coefficients. The thrust delivered by the cold-gas thruster and the specific impulse is determined based on the numerical results. Furthermore, an increase of the thickness of the viscous boundary layer through the diffuser of the micronozzle is observed. This results in a shock-less decrease of the Mach number and the flow velocity, which penalizes thrust efficiency. The negative effect of the viscous boundary layer on thrust efficiency can be lowered through higher values of Re and a reduction of the diffuser length.

  13. a Comprehensive Model for Capillary Pressure Difference across a Drop/bubble Flowing Through a Constricted Capillary

    NASA Astrophysics Data System (ADS)

    Liang, Mingchao; Wei, Junhong; Han, Hongmei; Fu, Chengguo; Liu, Jianjun

    2015-09-01

    The capillary pressure is one of the crucial parameters in many science and engineering applications such as composite materials, interface science, chemical engineering, oil exploration, etc. The drop/bubble formation and its mechanisms that affect the permeability of porous media have steadily attracted much attention in the past. When a drop/bubble moves from a larger capillary to a smaller one, it is often obstructed by an additional pressure difference caused by the capillary force. In this paper, a comprehensive model is derived for the capillary pressure difference when a drop/bubble flows through a constricted capillary, i.e. a geometrically constricted passage with an abrupt change in radius. The proposed model is expressed as a function of the smaller capillary radius, pore-throat ratio, contact angle, surface tension and length of the drop/bubble in the smaller capillary. The model predictions are compared with the available experimental data, and good agreement is found between them.

  14. Resonances, radiation pressure and optical scattering phenomena of drops and bubbles

    NASA Technical Reports Server (NTRS)

    Marston, P. L.; Goosby, S. G.; Langley, D. S.; Loporto-Arione, S. E.

    1982-01-01

    Acoustic levitation and the response of fluid spheres to spherical harmonic projections of the radiation pressure are described. Simplified discussions of the projections are given. A relationship between the tangential radiation stress and the Konstantinov effect is introduced and fundamental streaming patterns for drops are predicted. Experiments on the forced shape oscillation of drops are described and photographs of drop fission are displayed. Photographs of critical angle and glory scattering by bubbles and rainbow scattering by drops are displayed.

  15. The effect of pressure on annular flow pressure drop in a small pipe

    SciTech Connect

    de Bertodano, M.A.L.; Beus, S.G.; Shi, Jian-Feng

    1996-09-01

    New experimental data was obtained for pressure drop and entrainment for annular up-flow in a vertical pipe. The 9.5 mm. pipe has an L/D ratio of 440 to insure fully developed annular flow. The pressure ranged from 140 kPa to 660 kPa. Therefore the density ratio was varied by a factor of four approximately. This allows the investigation of the effect of pressure on the interfacial shear models. Gas superficial velocities between 25 and 126 m/s were tested. This extends the range of previous data to higher gas velocities. The data were compared with well known models for interfacial shear that represent the state of the art. Good results were obtained when the model by Asali, Hanratty and Andreussi was modified for the effect of pressure. Furthermore an equivalent model was obtained based on the mixing length theory for rough pipes. It correlates the equivalent roughness to the film thickness.

  16. Pressure drop control using multiple orifice system in compressible pipe flows

    NASA Astrophysics Data System (ADS)

    Kim, Heuydong; Setoguchi, Toshiaki; Matsuo, Shigeru; Raghunathan, S. R.

    2001-10-01

    In order to investigate the effectiveness of an orifice system in producing pressure drops and the effect of compressibility on the pressure drop, computations using the mass-averaged implicit Navier-Stokes equations were applied to the axisymmetric pipe flows with the operating pressure ratio from 1.5 to 20.0. The standard k- ɛ turbulence model was employed to close the governing equations. Numerical calculations were carried out for some combinations of the multiple orifice configurations. The present CFD data showed that the orifice systems, which have been applied to incompressible flow regime to date, could not be used for the high operating pressure ratio flows. The orifice interval did not strongly affect the total pressure drop, but the orifice area ratio more than 2.5 led to relatively high pressure drops. The total pressure drop rapidly increased in the range of the operating pressure ratio from 1.5 to 4.0, but it nearly did not increase when the operating pressure ratio was over 4.0. In the compressible pipe flows through double and triple orifice systems, the total pressure drop was largely due to shock losses.

  17. Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature

    NASA Technical Reports Server (NTRS)

    Jentung, Ku; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.

  18. Water management of proton exchange membrane fuel cell based on control of hydrogen pressure drop

    NASA Astrophysics Data System (ADS)

    Song, Mancun; Pei, Pucheng; Zha, Hongshan; Xu, Huachi

    2014-12-01

    Flooding experiments in various conditions are developed and the hydrogen pressure drop is investigated on a two-piece PEM fuel cell in this study. A two-level characteristic of hydrogen pressure drop is observed and analyzed in combination with water droplet accumulation in channels. Based on the characteristic, the flooding process can be divided into four continuous periods, which are the proper period, the humid period, the transitional period and the flooding period. The voltage shows the segmented tendency during these periods. Experimental results show that current and temperature have little influence on the growth rate of the two levels, while the effects of pressure and hydrogen stoichiometry are remarkable. The growth rate can be calculated through the channel dimensions and matches the experimental results well. Hydrogen purge is not a fundamental method to solve flooding. The end of the humid period should be the boundary before flooding. The moist section can be obtained in the beginning part of the humid period. In this section PEM fuel cell is neither flooding nor dehydration by adjusting the cell temperature, which is verified by two additional experiments. This water management is convenient and swift for PEM fuel cell applications and the fault diagnosis.

  19. LHe Flow Regime/Pressure Drop for D0 Solenoid at Steady State Conditions

    SciTech Connect

    Rucinski, R.; /Fermilab

    1993-03-03

    This paper describes in a note taking format what was learned from several sources on two phase liquid helium flow regimes and pressure drops as applied to the D-Zero solenoid upgrade project. Calculations to estimate the steady state conditions for the D-Zero solenoid at 5, 10 and 15 g/s are also presented. For the lower flow rates a stratified type regime can be expected with a pressure drop less than 0.5 psi. For the higher flow rate a more homogeneous flow regime can be expected with a pressure drop between 0.4 to 1.5 psi.

  20. Laboratory manual for static pressure drop experiments in LMFBR wire wrapped rod bundles

    SciTech Connect

    Burns, K.J.; Todreas, N.E.

    1980-07-01

    Purpose of this experiment is to determine both interior and edge subchannel axial pressure drops for a range of Reynolds numbers. The subchannel static pressure drop is used to calculate subchannel and bundle average friction factors, which can be used to verify existing friction factor correlations. The correlations for subchannel friction factors are used as input to computer codes which solve the coupled energy, continuity, and momentum equations, and are also used to develop flow split correlations which are needed as input to codes which solve only the energy equation. The bundle average friction factor is used to calculate the overall bundle pressure drop, which determines the required pumping power.

  1. Compressibility Effects on Heat Transfer and Pressure Drop in Smooth Cylindrical Tubes

    NASA Technical Reports Server (NTRS)

    Nielsen, Jack N

    1944-01-01

    An analysis is made to simplify pressure-drop calculations for nonadiabatic and adiabatic friction flow of air in smooth cylindrical tubes when the density changes due to heat transfer and pressure drop are appreciable. Solutions of the equation of motion are obtained by the use of Reynolds' analogy between heat transfer and skin friction. Charts of the solutions are presented for making pressure-drop calculations. A technique of using the charts to determine the position of a normal shock in a tube is described.

  2. Influence of Biofuel Additions on the Ignition Delay of Single Diesel Fuel Drops

    NASA Astrophysics Data System (ADS)

    Kopeika, A. K.; Golovko, V. V.; Zolotko, A. N.; Raslavičius, L.; Lubarskii, V. M.

    2015-07-01

    The behavior of single drops of two- and three-component mineral diesel fuel blends with ethanol and rapeseed oil methyl ester in a heated atmosphere has been investigated. With the use of the known quasi-stationary approach, the influence of the thermal properties of fuel blend components and their composition on the ignition delay time of the drop has been investigated. It has been established that under inert heating conditions of the drop, additions of low-boiling ethanol to diesel fuel should shorten the duration of the preignition period, and additions of rapeseed oil methyl ester should, on the contrary, prolong it. Analysis of the obtained data has made it possible to determine the optimal composition of the fuel blend for the most economical operation of the diesel. The prognostic estimates made are confirmed by laboratory experiments and bench tests of fuel blends.

  3. Heat transfer and pressure drop for air flow through enhanced passages

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  4. Heat transfer and pressure drop for air flow through enhanced passages. Final report

    SciTech Connect

    Obot, N.T.; Esen, E.B.

    1992-06-01

    An extensive experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for laminar, transitional and turbulent flow of air through a smooth passage and twenty-three enhanced passages. The internal surfaces of all enhanced passages had spirally shaped geometries; these included fluted, finned/ribbed and indented surfaces. The Reynolds number (Re) was varied between 400 and 50000. The effect of heat transfer (wall cooling or fluid heating) on pressure drop is most significant within the transition region; the recorded pressure drop with heat transfer is much higher than that without heat transfer. The magnitude of this effect depends markedly on the average surface temperature and, to a lesser extent, on the geometric characteristics of the enhanced surfaces. When the pressure drop data are reduced as values of the Fanning friction factor(f), the results are about the same with and without heat transfer for turbulent flow, with moderate differences in the laminar and transition regions.

  5. Cyclone optimization based on a new empirical model for pressure drop

    SciTech Connect

    Ramachandran, G.; Leith, D. ); Dirgo, J. ); Feldman, H. )

    1991-01-01

    An empirical model for predicting pressure drop across a cyclone, developed by Dirgo is presented. The model was developed through a statistical analysis of pressure drop data for 98 cyclone designs. The model is shown to perform better than the pressure drop models of Shepherd and Lapple, Alexander, First, Stairmand, and Barth. This model is used with the efficiency model of Iozia and Leith to develop an optimization curve which predicts the minimum pressure drop and the dimension ratios of the optimized cyclone for a given aerodynamic cut diameter, d{sub 50}. The effect of variation in cyclone height, cyclone diameter, and flow on the optimization is determined. The optimization results are used to develop a design procedure for optimized cyclones.

  6. Pressure-drops control strategy in a fixed-bed reactor.

    PubMed

    Thalasso, F; Razo-Flores, E; Ancia, R; Naveau, H P; Nyns, E J

    2001-01-29

    This paper presents a strategy to control pressure-drops (head loss) in a biofilter designed according to the "Mist-Foam" concept. This concept is based on the mixing of the gaseous substrate and a liquid nutrient solution with an atomization nozzle to generate a mist passing subsequently through a synthetic polyurethane foam. In this type of bioreactor, the microbial growth reduces progressively the empty bed volume of the biofilter and causes an increase in the pressure-drops. This phenomenon can result in a complete clogging of the biofilter. The strategy of pressure-drops control presented here consists of successive interruption of the liquid flow, automatically controlled, resulting in a drying effect of the biomass. Tested during a 160 days experiment, this system has permitted to reduce and stabilize the pressure-drops in a biofilter in which the carrier exhibited a high likelihood of clogging. PMID:11118687

  7. Effects of pressure drop and superficial velocity on the bubbling fluidized bed incinerator.

    PubMed

    Wang, Feng-Jehng; Chen, Suming; Lei, Perng-Kwei; Wu, Chung-Hsing

    2007-12-01

    Since performance and operational conditions, such as superficial velocity, pressure drop, particles viodage, and terminal velocity, are difficult to measure on an incinerator, this study used computational fluid dynamics (CFD) to determine numerical solutions. The effects of pressure drop and superficial velocity on a bubbling fluidized bed incinerator (BFBI) were evaluated. Analytical results indicated that simulation models were able to effectively predict the relationship between superficial velocity and pressure drop over bed height in the BFBI. Second, the models in BFBI were simplified to simulate scale-up beds without excessive computation time. Moreover, simulation and experimental results showed that minimum fluidization velocity of the BFBI must be controlled in at 0.188-3.684 m/s and pressure drop was mainly caused by bed particles. PMID:18074287

  8. 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.

  9. Liquid-metal, pin-fin pressure drop by correlation in cross flow

    SciTech Connect

    Wang, Z.; Kuzay, T.M.; Assoufid, L. )

    1995-02-01

    The pin-fin configuration is widely used in high-heat-flux applications. Recently, the pin-fin design with liquid-metal coolant was also applied to synchrotron-radiation beamline devices. This article investigates the pressure drop in a pin-post crystal with liquid gallium as the coolant. Because the pin-post configuration is a relatively new concept, information in the literature on pin-post mirrors or crystals is rare, and information on the pressure drop in pin-post mirrors with liquid metal as the coolant is even rarer. Because the cross flow in cylinder-array geometry is very similar to that of the pin post, the pressure drop correlation data for the cross flow of fluid with various fluid characteristics or properties through a tube bank are studied so that the results can be scaled to the pin-fin geometry with liquid metal as the coolant. The emphasis of this article is on the influence of two variables on the pressure drop: viscosity and density of fluid. The difference and correlation of the pressure drop between long and short posts and the predication of the pressure drop of liquid metal in the pin-post mirror and comparison with an existing experiment are addressed.

  10. Effect of bed pressure drop on performance of a CFB boiler

    SciTech Connect

    Hairui Yang; Hai Zhang; Shi Yang; Guangxi Yue; Jun Su; Zhiping Fu

    2009-05-15

    The effect of bed pressure drop and bed inventory on the performances of a circulating fluidized bed (CFB) boiler was studied. By using the state specification design theory, the fluidization state of the gas-solids flow in the furnace of conventional CFB boilers was reconstructed to operate at a much lower bed pressure drop by reducing bed inventory and control bed quality. Through theoretical analysis, it was suggested that there would exist a theoretical optimal value of bed pressure drop, around which the boiler operation can achieve the maximal combustion efficiency and with significant reduction of the wear of the heating surface and fan energy consumption. The analysis was validated by field tests carried out in a 75 t/h CFB boiler. At full boiler load, when bed pressure drop was reduced from 7.3 to 3.2 kPa, the height of the dense zone in the lower furnace decreased, but the solid suspension density profile in the upper furnace and solid flow rate were barely influenced. Consequently, the average heat transfer coefficient in the furnace was kept nearly the same and the furnace temperature increment was less than 17{sup o}C. It was also found that the carbon content in the fly ash decreased first with decreasing bed pressure drop and then increased with further increasing bed pressure drop. The turning point with minimal carbon content was referred to as the point with optimal bed pressure drop. For this boiler, at the optimum point the bed pressure was around 5.7 kPa with the overall excess air ratio of 1.06. When the boiler was operated around this optimal point, not only the combustion efficiency was improved, but also fan energy consumption and wear of heating surface were reduced. 23 refs., 6 figs., 4 tabs.

  11. Experimental microbubble generation by sudden pressure drop and fluidics

    NASA Astrophysics Data System (ADS)

    Franco Gutierrez, Fernando; Figueroa Espinoza, Bernardo; Aguilar Corona, Alicia; Vargas Correa, Jesus; Solorio Diaz, Gildardo

    2014-11-01

    Mass and heat transfer, as well as chemical species in bubbly flow are of importance in environmental and industrial applications. Microbubbles are well suited to these applications due to the large interface contact area and residence time. The objective of this investigation is to build devices to produce microbubbles using two methods: pressure differences and fluidics. Some characteristics, advantages and drawbacks of both methods are briefly discussed, as well as the characterization of the bubbly suspensions in terms of parameters such as the pressure jump and bubble equivalent diameter distribution. The authors acknowledge the support of Consejo Nacional de Ciencia y Tecnología.

  12. Novel cyclone empirical pressure drop and emissions with heterogeneous particulate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New cyclone designs equally effective at controlling emissions that have smaller pressure losses would reduce both the financial and the environmental cost of procuring electricity. Tests were conducted with novel and industry standard 30.5 cm diameter cyclones at inlet velocities from 8 to 18 m s-...

  13. Novel cyclone pressure drop and emissions with heterogeneous particulate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New cyclone designs equally effective at controlling emissions that have smaller pressure losses would reduce both the financial and the environmental cost of procuring electricity. Tests were conducted with novel and industry standard 30.5 cm diameter cyclones at inlet velocities from 8 to 18 m s-...

  14. Pressure drop characteristics of cryogenic mixed refrigerant at macro and micro channel heat exchangers

    NASA Astrophysics Data System (ADS)

    Baek, Seungwhan; Jeong, Sangkwon; Hwang, Gyuwan

    2012-12-01

    Mixed Refrigerant-Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. The temperature glide effect is one of the major features of using mixed refrigerants since a recuperative heat exchanger in a MR-JT refrigerator is utilized for mostly two-phase flow. Although a pressure drop estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in MR-JT refrigerator heat exchanger designs, it has been rarely discussed so far. In this paper, macro heat exchangers and micro heat exchangers are compared in order to investigate the pressure drop characteristics in the experimental MR-JT refrigerator operation. The tube in tube heat exchanger (TTHE) is a well-known macro-channel heat exchanger in MR-JT refrigeration. Printed Circuit Heat Exchangers (PCHEs) have been developed as a compact heat exchanger with micro size channels. Several two-phase pressure drop correlations are examined to discuss the experimental pressure measurement results. The result of this paper shows that cryogenic mixed refrigerant pressure drop can be estimated with conventional two-phase pressure drop correlations if an appropriate flow pattern is identified.

  15. Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

    SciTech Connect

    Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

    2014-01-29

    A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models.

  16. Pressure Drop and Heat Transfer Characteristics of Boiling Nitrogen in Square Pipe flow

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Nakayama, Tadashi; Takahashi, Koichi; Kobayashi, Hiroaki; Taguchi, Hideyuki; Aoki, Itsuo

    Pressure drop and forced convection heat transfer were studied in the boiling nitrogen flow in a horizontal square pipe with a side of 12 mm at inlet pressure between 0.1 and0.15 MPa with a mass flux between 70 and 2000 kg/m2-s and with a heat flux of 5, 10 and 20 kW/m2. Accordingly, the flow and heat transfer mechanisms specific to square pipe were elucidated, and the applicability to cryogenic fluids of pressure drop and heat transfer models originally proposed for room temperature fluids was clarified.

  17. Active control of static pressure drop caused by hydraulic servo-actuator engage

    SciTech Connect

    Janlovic, J.

    1994-12-31

    Pressure drop caused by propagation of expansion waves in the source pipeline of fast high cyclic hydraulic actuator produces possible anomalies in its function. To prevent pressure drop it is possible to minimize wave effects by active control of actuator servo-valve throttle leakage. In the paper is presented synthesis of possible discrete active control of hydraulic actuator and its servo-valve for prevention expansion wave pressure drop. Control synthesis is based on static pressure increasing with decreasing of fluid flow velocity, which can be realized by lower throttle leakage. Some of the effects of assumed control are shown on corresponding diagrams of control valve throttle motion, piston displacement and its corresponding linear velocity.

  18. Negative pressures and spallation in water drops subjected to nanosecond shock waves

    DOE PAGESBeta

    Stan, Claudiu A.; Willmott, Philip R.; Stone, Howard A.; Koglin, Jason E.; Liang, Mengning; Aquila, Andrew L.; Robinson, Joseph S.; Gumerlock, Karl L.; Blaj, Gabriel; Sierra, Raymond G.; et al

    2016-05-16

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below –100 MPamore » were reached in the drops. As a result, we model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.« less

  19. Effect of flameholder pressure drop on emissions and performance of premixed-prevaporized combustors

    NASA Technical Reports Server (NTRS)

    Duerr, R. A.; Lyons, V. J.

    1983-01-01

    Parametric tests were conducted to determine the effects of flameholder pressure drop on the emissions and performance of lean premixed-prevaporized combustors. A conical flameholder mounted in a diverging duct was tested with two values of flameholder blockage. Emissions of nitrogen oxides, carbon monoxide, carbon dioxide, and unburned hydrocarbons were measured for combustor entrance conditions of 600 to 800 K air temperature, 0.3 MPa to 0.5 MPa pressure, and 20 m/sec to 35 m/sec reference velocity. Jet A fuel was injected at flow rates corresponding to an equivalence ratio range from 0.8 down to the lean stability limit. Emission results for the high-blockage flameholder were a substantial improvement over the low-blockage emission results. A correlation of combustion efficiency with flameholder pressure drop was developed for pressure drops less than 9 percent.

  20. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves.

    PubMed

    Stan, Claudiu A; Willmott, Philip R; Stone, Howard A; Koglin, Jason E; Liang, Mengning; Aquila, Andrew L; Robinson, Joseph S; Gumerlock, Karl L; Blaj, Gabriel; Sierra, Raymond G; Boutet, Sébastien; Guillet, Serge A H; Curtis, Robin H; Vetter, Sharon L; Loos, Henrik; Turner, James L; Decker, Franz-Josef

    2016-06-01

    Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below -100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures. PMID:27182751

  1. Nucleate boiling pressure drop in an annulus: Book 5

    SciTech Connect

    Not Available

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux. This document consists solely of the plato file index from 11/87 to 11/90.

  2. A Validated All-Pressure Fluid Drop Model and Lewis Number Effects for a Binary Mixture

    NASA Technical Reports Server (NTRS)

    Harstad, K.; Bellan, J.

    1999-01-01

    The differences between subcritical liquid drop and supercritical fluid drop behavior are discussed. Under subcritical, evaporative high emission rate conditions, a film layer is present in the inner part of the drop surface which contributes to the unique determination of the boundary conditions; it is this film layer which contributes to the solution's convective-diffusive character. In contrast, under supercritical condition as the boundary conditions contain a degree of arbitrariness due to the absence of a surface, and the solution has then a purely diffusive character. Results from simulations of a free fluid drop under no-gravity conditions are compared to microgravity experimental data from suspended, large drop experiments at high, low and intermediary temperatures and in a range of pressures encompassing the sub-and supercritical regime. Despite the difference between the conditions of the simulations and experiments (suspension vs. free floating), the time rate of variation of the drop diameter square is remarkably well predicted in the linear curve regime. The drop diameter is determined in the simulations from the location of the maximum density gradient, and agrees well with the data. It is also shown that the classical calculation of the Lewis number gives qualitatively erroneous results at supercritical conditions, but that an effective Lewis number previously defined gives qualitatively correct estimates of the length scales for heat and mass transfer at all pressures.

  3. Nucleate boiling pressure drop in an annulus: Book 2

    SciTech Connect

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux.

  4. Experimental study of the effect of drag reducing agent on pressure drop and thermal efficiency of an air cooler

    NASA Astrophysics Data System (ADS)

    Peyghambarzadeh, S. M.; Hashemabadi, S. H.; Saffarian, H.; Shekari, F.

    2016-01-01

    Effect of polymeric drag reduction agents (DRAs) on pressure drop and heat transfer was studied. Aqueous solutions of carboxy methyl cellulose were used inside an air-finned heat exchanger. Despite the previous studies which indicated the importance of drag reduction just in turbulent flow, results of this study in laminar flow indicated that the addition of DRA increases drag reduction, and decreases the overall heat transfer coefficient.

  5. Effect of superficial velocity on vaporization pressure drop with propane in horizontal circular tube

    NASA Astrophysics Data System (ADS)

    Novianto, S.; Pamitran, A. S.; Nasruddin, Alhamid, M. I.

    2016-06-01

    Due to its friendly effect on the environment, natural refrigerants could be the best alternative refrigerant to replace conventional refrigerants. The present study was devoted to the effect of superficial velocity on vaporization pressure drop with propane in a horizontal circular tube with an inner diameter of 7.6 mm. The experiments were conditioned with 4 to 10 °C for saturation temperature, 9 to 20 kW/m2 for heat flux, and 250 to 380 kg/m2s for mass flux. It is shown here that increased heat flux may result in increasing vapor superficial velocity, and then increasing pressure drop. The present experimental results were evaluated with some existing correlations of pressure drop. The best prediction was evaluated by Lockhart-Martinelli (1949) with MARD 25.7%. In order to observe the experimental flow pattern, the present results were also mapped on the Wang flow pattern map.

  6. Heat Transfer and Pressure Drop in Concentric Annular Flows of Binary Inert Gas Mixtures

    NASA Technical Reports Server (NTRS)

    Reid, R. S.; Martin, J. J.; Yocum, D. J.; Stewart, E. T.

    2007-01-01

    Studies of heat transfer and pressure drop of binary inert gas mixtures flowing through smooth concentric circular annuli, tubes with fully developed velocity profiles, and constant heating rate are described. There is a general lack of agreement among the constant property heat transfer correlations for such mixtures. No inert gas mixture data exist for annular channels. The intent of this study was to develop highly accurate and benchmarked pressure drop and heat transfer correlations that can be used to size heat exchangers and cores for direct gas Brayton nuclear power plants. The inside surface of the annular channel is heated while the outer surface of the channel is insulated. Annulus ratios range 0.5 < r* < 0.83. These smooth tube data may serve as a reference to the heat transfer and pressure drop performance in annuli, tubes, and channels having helixes or spacer ribs, or other surfaces.

  7. Analysis of MHD Pressure Drop in the Packed Pebble Bed-Based Blanket for the Fds

    NASA Astrophysics Data System (ADS)

    Wang, Hongyan; Wu, Yican; He, Xiaoxiong

    2003-06-01

    The Fusion-Driven Sub-critical System as a multifunctional hybrid reactor has been investigated in ASIPP. The liquid metal LiPb flow through a packed pebble bed-based blanket is considered to be one of the blanket candidates. In this contribution, the MHD pressure drop of liquid metal flow through the packed pebble bed has been calculated and analyzed under various conditions including (a) the size of the packed pebbles; (b) the ratio of occupied room by the packed pebbles to that of liquid metal; and (c) whether the pebbles surface is insulated or not Furthermore, asymptotic techniques to analyze large Hartmann parameter flow and interaction parameter flow are employed and an analytical model has been developed for the calculations of MHD pressure drop of liquid metal flow in a packed pebble bed. The appropriate method for calculating the MHD effects on the pressure drop through the packed pebble bed-based blanket for the FDS has been presented.

  8. Pressure drop measurements on supercritical helium cooled cable in conduit conductors

    NASA Astrophysics Data System (ADS)

    Daugherty, M. A.; Huang, Y.; Vansciver, S. W.

    1988-08-01

    Forced flow cable-in-conduit conductors with large cooled surface areas provide excellent stability margins at the price of high frictional losses and large pumping power requirements. For extensive projects such as the International Thermonuclear Experimental Reactor design cooperation, it is essential to know the pressure drops to be expected from different conductor geometries and operating conditions. To measure these pressure drops a flow loop was constructed to circulate supercritical helium through different conductors. The loop is surrounded by a 5 K radiation shield to allow for stable operation at the required temperatures. A coil heat exchanger immersed in a helium bath is used to remove the heat generated by the pump. Pressure drops are measured across 1 meter lengths of the conductors for various mass flow rates. Friction factor versus Reynolds number plots are used to correlate the data.

  9. Measurements of pressure drop and heat transfer in turbulent pipe flows of particulate slurries

    NASA Astrophysics Data System (ADS)

    Liu, K. V.; Choi, U. S.; Kasza, K. E.

    1988-05-01

    Argonne National Laboratory (ANL), under sponsorhip of DOE, Office of Buildings and Community Systems, has been conducting a comprehensive, long-range program to develop high-performance advanced energy transmission fluids for use in district heating and cooling (DHC) systems. The current study focuses on the development of phase-change slurries as advanced energy transmission fluids. The objectives are: (1) to establish proof-of-concept of enhanced heat transfer by a slurry, with and without phase change, relative to heat transfer in a pure carrier liquid; (2) to investigate the effect of particle volumetric loading, size, and flow rate on the slurry pressure drip and heat transfer behavior with and without friction-reducing additives; and (3) to generate pressure drop and heat transfer data needed for the development and design of improved DHC systems. Two types of phase-change materials were used in the experiments: ice slush for cooling, and cross-linked, high- density polyethylene (X-HDPE) particles with diameters of 1/8 and 1/20 in. (3.2 and 1.3 mm) for heating. The friction-reducing additive used in the tests was Separan AP-272 at 65 wppm. This report describes the test facility, discusses the experimental procedures, and presents significant experimental results on flow and heat transfer characteristics of the non-melting slurry flows.

  10. An improved correlation of the pressure drop in stenotic vessels using Lorentz's reciprocal theorem

    NASA Astrophysics Data System (ADS)

    Ji, Chang-Jin; Sugiyama, Kazuyasu; Noda, Shigeho; He, Ying; Himeno, Ryutaro

    2015-02-01

    A mathematical model of the human cardiovascular system in conjunction with an accurate lumped model for a stenosis can provide better insights into the pressure wave propagation at pathological conditions. In this study, a theoretical relation between pressure drop and flow rate based on Lorentz's reciprocal theorem is derived, which offers an identity to describe the relevance of the geometry and the convective momentum transport to the drag force. A voxel-based simulator V-FLOW VOF3D, where the vessel geometry is expressed by using volume of fluid (VOF) functions, is employed to find the flow distribution in an idealized stenosis vessel and the identity was validated numerically. It is revealed from the correlation that the pressure drop of NS flow in a stenosis vessel can be decomposed into a linear term caused by Stokes flow with the same boundary conditions, and two nonlinear terms. Furthermore, the linear term for the pressure drop of Stokes flow can be summarized as a correlation by using a modified equation of lubrication theory, which gives favorable results compared to the numerical ones. The contribution of the nonlinear terms to the pressure drop was analyzed numerically, and it is found that geometric shape and momentum transport are the primary factors for the enhancement of drag force. This work paves a way to simulate the blood flow and pressure propagation under different stenosis conditions by using 1D mathematical model.

  11. Nucleate boiling pressure drop in an annulus: Book 8

    SciTech Connect

    Not Available

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of tables of temperature measurements.

  12. Nucleate boiling pressure drop in an annulus: Book 4

    SciTech Connect

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  13. Fundamental study of transpiration cooling. [pressure drop and heat transfer data from porous metals

    NASA Technical Reports Server (NTRS)

    Koh, J. C. Y.; Dutton, J. L.; Benson, B. A.

    1973-01-01

    Isothermal and non-isothermal pressure drop data and heat transfer data generated on porous 304L stainless steel wire forms, sintered spherical stainless steel powder, and sintered spherical OFHC copper powder are reported and correlated. Pressure drop data was collected over a temperature range from 500 R to 2000 R and heat transfer data collected over a heat flux range from 5 to 15 BTU/in2/sec. It was found that flow data could be correlated independently of transpirant temperature and type (i.e., H2, N2). It was also found that no simple relation between heat transfer coefficient and specimen porosity was obtainable.

  14. A steady state pressure drop model for screen channel liquid acquisition devices

    NASA Astrophysics Data System (ADS)

    Hartwig, J. W.; Darr, S. R.; McQuillen, J. B.; Rame, E.; Chato, D. J.

    2014-11-01

    This paper presents the derivation of a simplified one dimensional (1D) steady state pressure drop model for flow through a porous liquid acquisition device (LAD) inside a cryogenic propellant tank. Experimental data is also presented from cryogenic LAD tests in liquid hydrogen (LH2) and liquid oxygen (LOX) to compare against the simplified model and to validate the model at cryogenic temperatures. The purpose of the experiments was to identify the various pressure drop contributions in the analytical model which govern LAD channel behavior during dynamic, steady state outflow. LH2 pipe flow of LAD screen samples measured the second order flow-through-screen (FTS) pressure drop, horizontal LOX LAD outflow tests determined the relative magnitude of the third order frictional and dynamic losses within the channel, while LH2 inverted vertical outflow tests determined the magnitude of the first order hydrostatic pressure loss and validity of the full 1D model. When compared to room temperature predictions, the FTS pressure drop is shown to be temperature dependent, with a significant increase in flow resistance at LH2 temperatures. Model predictions of frictional and dynamic losses down the channel compare qualitatively with LOX LADs data. Meanwhile, the 1D model predicted breakdown points track the trends in the LH2 inverted outflow experimental results, with discrepancies being due to a non-uniform injection velocity across the LAD screen not accounted for in the model.

  15. Testing of a 4 K to 2 K heat exchanger with an intermediate pressure drop

    SciTech Connect

    Knudsen, Peter N.; Ganni, Venkatarao

    2015-12-01

    Most large sub-atmospheric helium refrigeration systems incorporate a heat exchanger at the load, or in the distribution system, to counter-flow the sub-atmospheric return with the super-critical or liquid supply. A significant process improvement is theoretically obtainable by handling the exergy loss across the Joule-Thompson throttling valve supplying the flow to the load in a simple but different manner. As briefly outlined in previous publications, the exergy loss can be minimized by allowing the supply flow pressure to decrease to a sub-atmospheric pressure concurrent with heat exchange flow from the load. One practical implementation is to sub-divide the supply flow pressure drop between two heat exchanger sections, incorporating an intermediate pressure drop. Such a test is being performed at Jefferson Lab's Cryogenic Test Facility (CTF). This paper will briefly discuss the theory, practical implementation and test results and analysis obtained to date.

  16. Model calibration for pressure drop in a pulse-jet cleaned fabric filter

    NASA Astrophysics Data System (ADS)

    Koehler, John L.; David, Leith

    A model based on Darcy's law allows prediction of pressure drop in a pulse-jet cleaned fabric filter. The model considers the effects of filtration velocity, dust areal density added during one filtration cycle, and pulse pressure. Data used to calibrate the model were collected in experiments with three fabric surface treatments and three dusts conducted at three filtration velocities, for a total of 27 different experimental conditions. The fabric used was polyester felt with untreated, singed, or PTFE-laminated surface. The dusts used were granite, limestone and fly ash. Filtration velocities were 50,75 and 100 mm s -1. Dust areal density added during one filtration cycle was constant, as was pulse pressure. Under these conditions, fabric surface treatment alone largely determined the values for two of the three constants in the model; the third constant depends on pressure drop characteristics of the venturi at the top of each filter bag.

  17. Review of Singular Cooling Inlet and Linear Pressure Drop for ITER Coils Cable in Conduit Conductor

    NASA Astrophysics Data System (ADS)

    Nicollet, S.; Bessette, D.; Cloez, H.; Decool, P.; Lacroix, B.; Lebailly, C. A.; Serries, J. P.

    2006-04-01

    New tests and measurements performed (Othello Facility, EFDA Task) on TF mock up cooling inlet and different central spirals (characteristics: hydraulic outer diameter and perforation ratio) are presented, as well as the new model of singular and linear friction factor. The ITER Coils CICC hydraulic length pressure drop is determined in operating conditions (m=8 g/s, P=0.6 MPa and T=5 K): the important result is an increase in linear pressure drop for the TF (290 Pa/m) and CS (430 Pa/m), in comparison with prototype model coils TFMC (100 Pa/m) and CSMC (180 Pa/m). The main reason is the reduction of the central spiral diameter and associated increase of friction factor and bundle to total mass flow ratio α (from 1/3 up to 2/3 typically). The ratio of singular cooling inlet to CICC linear pressure drop is estimated: TF mock up ratio (3 m) is lower than previous CS mock up tested (12 m), due to design changes. The cryogenic power necessary to compensate the CICC pressure drop is calculated for the 4 primary loop circuits: typically 2.3 kW at 5 K for TF winding system represents 40% of the whole average TF winding magnet heat loads during operation.

  18. An experimental study of heat transfer and pressure drop characteristics of divergent wavy minichannels using nanofluids

    NASA Astrophysics Data System (ADS)

    Dominic, A.; Sarangan, J.; Suresh, S.; Devahdhanush, V. S.

    2016-07-01

    An experimental investigation was conducted to study the heat transfer and pressure drop characteristics of an array of wavy divergent minichannels and the results were compared with wavy minichannels with constant cross-section. The experiment was conducted in hydro dynamically developed and thermally developing laminar and transient regimes. The minichannel heat sink array consisted of 15 rectangular channels machined on a 30 × 30 mm2 and 11 mm thick Aluminium substrate. Each minichannel was of 0.9 mm width, 1.8 mm pitch and the depth was varied from 1.3 mm at entrance to 3.3 mm at exit for the divergent channels. DI water and 0.5 and 0.8 % concentrations of Al2O3/water nanofluid were used as working fluids. The Reynolds number was varied from 700 to 3300 and the heat flux was maintained at 45 kW/m2. The heat transfer and pressure drop of these minichannels were analyzed based on the experimental results obtained. It was observed that the heat transfer performance of divergent wavy minichannels was 9 % higher and the pressure drop was 30-38 % lesser than that of the wavy minichannels with constant cross-section, in the laminar regime. Hence, divergent channel flows can be considered one of the better ways to reduce pressure drop. The performance factor of divergent wavy minichannels was 115-126 % for water and 110-113 % for nanofluids.

  19. Determining Seed Cotton Mass Flow Rate by Pressure Drop Across a Blowbox: Gin Testing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate measurement of the mass flow rate of seed cotton is needed for control and monitoring purposes in gins. A system was developed that accurately predicted mass flow rate based on the static pressure drop measured across the blowbox and the air velocity and temperature entering the blowbox. Ho...

  20. Effects of Fin Shape on Condensation Heat Transfer and Pressure Drop inside Herringbone Micro Fin Tubes

    NASA Astrophysics Data System (ADS)

    Miyara, Akio; Otsubo, Yusuke; Ohtsuka, Satoshi

    Experiments of in-tube condensation of R410A have been carried out for as mooth tube, a h elical micro fin tube and five types of herringbone micro fin tubes. In the herringbone micro fin tube, the micro fins work to remove liquid at fin-diverging parts and collect liquid at fin-converging parts. In the high mass velocity region, heat transfer coefficient of all the herringbone tubes is about 2-4 times higher than that of the helical micro fin tube. In the low mass velocity region, however, the heat transfer coefficients of the herringbone micro fin tubes are equal to or smaller than those of the helical micro fin tube. Up to the fin height of 0.18 mm, the heat transfer coefficient is higher for higher fin, whereas that of ah igher fin tube is saturated. The pressure drop increases with increasing fin height. The helix angle strongly affects the heat transfer and pressure drop. Higher helix angle causes higher heat transfer coefficient and higher pressure drop. In the case of the herringbone tube which has shorter fin and/or smaller helix angle, pressure drops are equal to or lower than that of the helical micro fin tube, whereas those of other tubes are higher.

  1. Prediction of pressure drop in fluid tuned mounts using analytical and computational techniques

    NASA Technical Reports Server (NTRS)

    Lasher, William C.; Khalilollahi, Amir; Mischler, John; Uhric, Tom

    1993-01-01

    A simplified model for predicting pressure drop in fluid tuned isolator mounts was developed. The model is based on an exact solution to the Navier-Stokes equations and was made more general through the use of empirical coefficients. The values of these coefficients were determined by numerical simulation of the flow using the commercial computational fluid dynamics (CFD) package FIDAP.

  2. New Results in Two-Phase Pressure Drop Calculations at Reduced Gravity Conditions

    NASA Astrophysics Data System (ADS)

    Braisted, Jon; Kurwitz, Cable; Best, Frederick

    2004-02-01

    The mass, power, and volume energy savings of two-phase systems for future spacecraft creates many advantages over current single-phase systems. Current models of two-phase phenomena such as pressure drop, void fraction, and flow regime prediction are still not well defined for space applications. Commercially available two-phase modeling software has been developed for a large range of acceleration fields including reduced-gravity conditions. Recently, a two-phase experiment has been flown to expand the two-phase database. A model of the experiment was created in the software to determine how well the software could predict the pressure drop observed in the experiment. Of the simulations conducted, the computer model shows good agreement of the pressure drop in the experiment to within 30%. However, the software does begin to over-predict pressure drop in certain regions of a flow regime map indicating that some models used in the software package for reduced-gravity modeling need improvement.

  3. Pressure Drop and Heat Transfer of Water Flowing Shell-Side of Multitube Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Ohashi, Yukio; Hashizume, Kenichi

    Experimental studies on heat transfer augmentation in water-flowing shell sides of counter flow multitube exchangers are presented. Various kinds of augmented tube bundles have been examined to obtain the characteristics of pressure drop and heat transfer. Data for a smooth tube bundle were a little different from those for the tube side. The pressure drop in the shell side depended on Re-0.4 and deviated from the tube side pressure drop to within +30%, while the shell side heat transfer coefficient depended on Re0.8 but about 35%. larger than that of the tube side. Furthermore the augmented tube bundles have been evaluated and compared using 21 evaluation criteria. Enhanced tube bundles, low-finned tube bundles and those with twisted tapes inserted had especially good performances. The ratios of increase in heat transfer were larger than those in pressure drop. In case of low-finned tube bundles, there seem to exist an optimum fin-pitch and an optimum relation between the fin-pitch and the pitch of twisted tapes inserted.

  4. Pressure drop and pumping power for fluid flow through round tubes

    NASA Technical Reports Server (NTRS)

    Jelinek, D.

    1973-01-01

    Program, written for Hewlett-Packard 9100A electronic desk computer provides convenient and immediate solution to problem of calculating pressure drop and fluid pumping power for flow through round tubes. Program was designed specifically for steady-state analysis and assumes laminar flow.

  5. Pressure drop of slush nitrogen flow in converging-diverging pipes and corrugated pipes

    NASA Astrophysics Data System (ADS)

    Ohira, Katsuhide; Okuyama, Jun; Nakagomi, Kei; Takahashi, Koichi

    2012-12-01

    Cryogenic slush fluids such as slush hydrogen and slush nitrogen are solid-liquid, two-phase fluids. As a functional thermal fluid, there are high expectations for use of slush fluids in various applications such as fuels for spacecraft engines, clean-energy fuels to improve the efficiency of transportation and storage, and as refrigerants for high-temperature superconducting equipment. Experimental flow tests were performed using slush nitrogen to elucidate pressure-drop characteristics of converging-diverging (C-D) pipes and corrugated pipes. In experimental results regarding pressure drop in two different types of C-D Pipes, i.e., a long-throated pipe and a short-throated pipe, each having an inner diameter of 15 mm, pressure drop for slush nitrogen in the long-throated pipe at a flow velocity of over 1.3 m/s increased by a maximum of 50-60% as compared to that for liquid nitrogen, while the increase was about 4 times as compared to slush nitrogen in the short-throated pipe. At a flow velocity of over 1.5 m/s in the short-throated pipe, pressure drop reduction became apparent, and it was confirmed that the decrease in pressure drop compared to liquid nitrogen was a maximum of 40-50%. In the case of two different types of corrugated pipes with an inner diameter of either 12 mm or 15 mm, a pressure-drop reduction was confirmed at a flow velocity of over 2 m/s, and reached a maximum value of 37% at 30 wt.% compared to liquid nitrogen. The greater the solid fractions, the smaller the pipe friction factor became, and the pipe friction factor at the same solid fraction showed a constant value regardless of the Reynolds number. From the observation of the solid particles' behavior using a high-speed video camera and the PIV method, the pressure-drop reduction mechanisms for both C-D and corrugated pipes were demonstrated.

  6. KC-135 zero-gravity two phase flow pressure drop: Experiments and modeling

    NASA Astrophysics Data System (ADS)

    Lambert, Anne; Reinarts, Thomas R.; Best, Frederick R.; Hill, Wayne S.

    1991-01-01

    Two-phase flow, thermal management systems are currently being considered as an alternative to conventional, single phase systems for future space missions because of their potential to reduce overall system mass, size, and pumping power requirements. Knowledge of flow regime transitions, heat transfer characteristics, and pressure drop correlations is necessary to design and develop two-phase systems. This work is concerned with microgravity, two-phase flow pressure drop experiments. The data are those of a recent experiment (Hill and Best 1990) funded by the U.S. Air Force and conducted by Foster-Miller in conjunction with Texas A&M University. A boiling and condensing experiment was built in which R-12 was used as the working fluid. A Foster-Miller two phase pump was used to circulate a freon mixture and allow separate measurements of the vapor and liquid flow streams. The experimental package was flown five times aboard the NASA KC-135 aircraft which simulates 0-``g'' conditions by its parabolic flight trajectory. Test conditions included stratified and annual flow regimes in 1-``g'' which became bubbly, slug or annular flow regimes in 0-``g''. A portion of the current work outlines a methodology to analyze data for two-phase, 0-g experimental studies. A technique for correcting the raw pressure drop data collected from the test package is given. The Corrected pressure drop measurements are compared with predictive model. The corrected pressure drop measurements show no statistically significant difference between the 1-``g'' and 0-``g'' tests for mass flow rates between 0.00653 and 0.0544 kg/s in an 8 mm ID tube. An annular flow model gave the best overall predictions of pressure drop. The homogeneous, and Beattle and Whalley (1982) models showed good agreement with the pressure drops measured for the slug and bubbly/slug flow conditions. The two-phase multiplier deduced from the data appeared to follow the Martinelli-Nelson trend but at lower values than for

  7. In vivo validation of the in silico predicted pressure drop across an arteriovenous fistula.

    PubMed

    Browne, Leonard D; Griffin, Philip; Bashar, Khalid; Walsh, Stewart R; Kavanagh, Eamon G; Walsh, Michael T

    2015-06-01

    The creation of an arteriovenous fistula offers a unique example of vascular remodelling and adaption. Yet, the specific factors which elicit remodelling events which determine successful maturation or failure have not been unambiguously determined. Computational fluid dynamic (CFD) simulations are increasingly been employed to investigate the interaction between local hemodynamics and remodelling and can potentially be used to assist in clinical risk assessment of maturation or failure. However, these simulations are inextricably linked to their prescribed boundary conditions and are reliant on in vivo measurements of flow and pressure to ensure their validity. The study compares in vivo measurements of the pressure distribution across arteriovenous fistulae against a representative numerical model. The results of the study indicate relative agreement (error ≈ 8-10%) between the in vivo and CFD prediction of the mean pressure drop across the AVFs. The large pressure drop across the AVFs coincided with a palpable thrill (perivascular vibration) in vivo and fluctuations were observed in the numerical pressure drop signal due to flow instabilities arising at the anastomosis. This study provides a benchmark of the pressure distribution within an AVF and validates that CFD solutions are capable of replicating the abnormal physiological flow conditions induced by fistula creation. PMID:25753016

  8. Analyses of MHD Pressure Drop in a Curved Bend for Different Liquid Metals

    NASA Astrophysics Data System (ADS)

    Arshad, Kameel; Rafique, Muhammad; Majid, Asad

    In this research we have analyzed liquid-metal flow in a curved bend in the presence of a magnetic field, which acts in two transverse directions. The magnetic field along the x-axis varied as B0(R + x)-1, while the magnetic field in y-direction is kept constant. The duct has conducting vanadium walls and liquid metal (lithium, sodium and potassium) have been used as a coolant. Magneto hydrodynamic (MHD) equations in three dimensions have been developed in the modified toroidal coordinate system. Then these coupled set of equations are solved by using finite difference techniques and an extended SIMPLER algorithm approach and an estimation of MHD pressure drop has been made for three different liquid metals, namely lithium, sodium and potassium. The results for a curved bend indicate an immense axial MHD pressure drop. The axial MHD pressure drop for three liquid metals, increases for an increase in both kinds of magnetic fields. It has been found that the MHD pressure drop is maximum in the case of sodium and minimum in the case of lithium In this paper a detailed comparative analysis has been carried out to find a suitable fluid for the cooling of high heat flux components of a fusion reactor, which is compatible with liquid metal lithium blanket and can also remove the 5 MW m-2 heat flux falling on the limiter or diverter plate. We finally concluded that from MHD pressure drop point of view that liquid lithium is the best choice for cooling of high heat flux components of a fusion reactor

  9. Heat transfer and pressure drop measurements in an air/molten salt direct-contact heat exchanger

    SciTech Connect

    Bohn, M.S.

    1988-11-01

    This paper presents a comparison of experimental data with a recently published model of heat exchange in irrigated packed beds. Heat transfer and pressure drop were measured in a 150 mm (ID) column with a 610-mm bed of metal Pall rings. Molten nitrate salt and preheated air were the working fluids with a salt inlet temperature of approximately 440{degree}C and air inlet temperatures of approximately 230{degree}C. A comparison between the experimental data and the heat transfer model is made on the basis of heat transfer from the salt. For the range of air and salt flow rates tested, 0.3 to 1.2 kg/m{sup 2} s air flow and 6 to 18 kg/m{sup 2} s salt flow, the data agree with the model within 22% standard deviation. In addition, a model for the column pressure drop was validated, agreeing with the experimental data within 18% standard deviation over the range of column pressure drop from 40 to 1250 Pa/m. 25 refs., 7 figs., 2 tabs.

  10. Intercooler cooling-air weight flow and pressure drop for minimum drag loss

    NASA Technical Reports Server (NTRS)

    Reuter, J George; Valerino, Michael F

    1944-01-01

    An analysis has been made of the drag losses in airplane flight of cross-flow plate and tubular intercoolers to determine the cooling-air weight flow and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-air cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling air in flowing through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling air pressure drop and weight flow ratio are tabulated. Curves are presented to illustrate the results of the analysis.

  11. The oceanic response of the Turkish Straits System to an extreme drop in atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Book, Jeffrey W.; Jarosz, Ewa; Chiggiato, Jacopo; Beşiktepe, Åükrü

    2014-06-01

    Moorings across all four entry/exit sections of the Dardanelles Strait and the Bosphorus Strait simultaneously measured the response of the Turkish Straits System to the passage of a severe cyclonic storm that included an atmospheric pressure drop of more than 30 mbar in less than 48 h. The bottom pressure response at the Aegean Sea side of the Dardanelles Strait was consistent with an inverted barometer response, but the response at the other sections did not follow an inverted barometer, leading to a large bottom pressure gradient through the Turkish Straits System. Upper-layer flow toward the Aegean Sea was reversed by the storm and flow toward the Black Sea was greatly enhanced. Bottom pressure across the Sea of Marmara peaked 6 h after the passage of the storm's minimum pressure. The response on the Dardanelles side was a combination of sea elevation and pycnocline depth rise, and the response on the Bosphorus side was an even greater sea elevation rise and a drop in pycnocline depth. The peak in bottom pressure in the Sea of Marmara was followed by another reverse in the flow through the Dardanelles Strait as flow was then directed away from the Sea of Marmara in both straits. A simple conceptual model without wind is able to explain fluctuations in bottom pressure in the Sea of Marmara to a 0.89-0.96 level of correlation. This stresses the importance of atmospheric pressure dynamics in driving the mass flux of the Turkish Strait System for extreme storms.

  12. Pressure drop and temperature rise in He II flow in round tubes, Venturi flowmeters and valves

    NASA Technical Reports Server (NTRS)

    Walstrom, P. L.; Maddocks, J. R.

    1988-01-01

    Pressure drops in highly turbulent He II flow were measured in round tubes, valves, and Venturi flowmeters. Results are in good agreement with single-phase flow correlations for classical fluids. The temperature rise in flow in a round tube was measured, and found to agree well with predictions for isenthalpic expansion. Cavitation was observed in the venturis under conditions of low back pressure and high flow rate. Metastable superheating of the helium at the venturi throat was observed before the helium made a transition to saturation pressure.

  13. Pressure drop and heat transfer characteristics of boiling water in sub-hundred micron channel

    SciTech Connect

    Bhide, R.R.; Singh, S.G.; Sridharan, Arunkumar; Duttagupta, S.P.; Agrawal, Amit

    2009-09-15

    The current work focuses on the pressure drop, heat transfer and stability in two phase flow in microchannels with hydraulic diameter of less than one hundred microns. Experiments were conducted in smooth microchannels of hydraulic diameter of 45, 65 {mu}m, and a rough microchannel of hydraulic diameter of 70 {mu}m, with deionised water as the working fluid. The local saturation pressure and temperature vary substantially over the length of the channel. In order to correctly predict the local saturation temperature and subsequently the heat transfer characteristics, numerical techniques have been used in conjunction with the conventional two phase pressure drop models. The Lockhart-Martinelli (liquid-laminar, vapour-laminar) model is found to predict the two phase pressure drop data within 20%. The instability in two phase flow is quantified; it is found that microchannels of smaller hydraulic diameter have lesser instabilities as compared to their larger counterparts. The experiments also suggest that surface characteristics strongly affect flow stability in the two phase flow regime. The effect of hydraulic diameter and surface characteristics on the flow characteristics and stability in two phase flow is seldom reported, and is of considerable practical relevance. (author)

  14. An experimental investigation of pressure drop of aqueous foam in laminar tube flow

    SciTech Connect

    Blackwell, B.F.; Sobolik, K.B.

    1987-04-01

    This report is the first of two detailing pressure-drop and heat-transfer measurements made at the Foam Flow Heat Transfer Loop. The work was motivated by a desire to extend the application of aqueous foam from petroleum drilling to geothermal drilling. Pressure-drop measurements are detailed in this report; a forthcoming report (SAND85-1922) will describe the heat-transfer measurements. The pressure change across a 2.4-m (8-ft) length of the 2.588-cm (1.019-in.) ID test section was measured for liquid volume fractions between 0.05 and 0.35 and average velocities between 0.12 and 0.80 m/s (0.4 and 2.6 ft/s). The resulting pressure-drop/flow-rate data were correlated to a theoretical model for a Bingham plastic. Simple expressions for the dynamic viscosity and the yield stress as a function of liquid volume fraction were estimated.

  15. Swirls and splashes: pressure dependence of the airflow created by drop impact

    NASA Astrophysics Data System (ADS)

    Bischofberger, Irmgard; Mauser, Kelly W.; Ray, Bahni; Lee, Taehun; Nagel, Sidney R.; JFI; Department of Physics, University of Chicago, Chicago, IL 6063 Collaboration; Department of Mechanical Engineering, CCNY, NY 10031 Collaboration

    2013-11-01

    A drop impacting a solid surface with sufficient velocity will splash and emit many small droplets. However, removing the ambient air suppresses splashing completely. The transition between splashing and non-splashing occurs gradually: decreasing the air pressure systematically delays and eventually fully inhibits the occurrence of a splash. The mechanism by which the surrounding gas affects the drop dynamics remains unknown. We use modified Schlieren optics combined with high-speed video imaging to visualize the airflow created by the rapid spreading of the drop after it hits the substrate. We observe the generation of a vortex ring that is initially bound to the outer edge of the spreading liquid and subsequently detaches from the liquid to form a beautiful toroidal vortex sheet that expands and curls up into a roll. We have studied the dynamics of this vortex as a function of gas pressure and find that the sheet gets progressively smaller as the air pressure is decreased. This suggests a weakening of the vortex strength at low pressure. We acknowledge support from NSF MRSEC and PREM grants.

  16. Gas-liquid pressure drop in vertical internally wavy 90 bend

    SciTech Connect

    Benbella, Shannak; Al-Shannag, Mohammad; Al-Anber, Zaid A.

    2009-01-15

    Experiments of air water two-phase flow pressure drop in vertical internally wavy 90 bend have been carried out. The tested bends are flexible and made of stainless steel with inner diameter of 50 mm and various curvature radiuses of 200, 300, 400 and 500 mm. The experiments were performed under the following conditions of two-phase parameters; mass flux from 350 to 750 kg/m{sup 2} s. Gas quality from 1% to 50% and system pressure from 4 to 7.5 bar. The results demonstrate that the effect of the above-mentioned parameters is very significant at high ranges of mass flow quality. Due to the increasing of two-phase flow resistance, energy dissipations, friction losses and interaction of the two-phases in the vertical internally wavy 90 bend the total pressure drops are perceptible about 2-5 times grater than that in smooth bends. Based on the mass and energy balance as well as the presented experimental results, new empirical correlation has been developed to calculate the two-phase pressure drop and hence the two-phase friction factor of the tested bends. The correlation includes the relevant primary parameter, fit the data well, and is sufficiency accurate for engineering purposes. (author)

  17. Estimation of inspiratory pressure drop in neonatal and pediatric endotracheal tubes.

    PubMed

    Jarreau, P H; Louis, B; Dassieu, G; Desfrere, L; Blanchard, P W; Moriette, G; Isabey, D; Harf, A

    1999-07-01

    Endotracheal tubes (ETTs) constitute a resistive extra load for intubated patients. The ETT pressure drop (DeltaP(ETT)) is usually described by empirical equations that are specific to one ETT only. Our laboratory previously showed that, in adult ETTs, DeltaP(ETT) is given by the Blasius formula (F. Lofaso, B. Louis, L. Brochard, A. Harf, and D. Isabey. Am. Rev. Respir. Dis. 146: 974-979, 1992). Here, we also propose a general formulation for neonatal and pediatric ETTs on the basis of adimensional analysis of the pressure-flow relationship. Pressure and flow were directly measured in seven ETTs (internal diameter: 2.5-7.0 mm). The measured pressure drop was compared with the predicted drop given by general laws for a curved tube. In neonatal ETTs (2.5-3.5 mm) the flow regime is laminar. The DeltaP(ETT) can be estimated by the Ito formula, which replaces Poiseuille's law for curved tubes. For pediatric ETTs (4.0-7.0 mm), DeltaP(ETT) depends on the following flow regime: for laminar flow, it must be calculated by the Ito formula, and for turbulent flow, by the Blasius formula. Both formulas allow for ETT geometry and gas properties. PMID:10409556

  18. Effects of phosphoric acid sprayed into an incinerator furnace on the flue gas pressure drop at fabric filters.

    PubMed

    Takahashi, Shigetoshi; Hwang, In-Hee; Matsuto, Toshihiko

    2016-06-01

    Fabric filters are widely used to remove dust from flue gas generated by waste incineration. However, a pressure drop occurs at the filters, caused by growth of a dust layer on the filter fabric despite regular cleaning by pulsed-jet air. The pressure drop at the fabric filters leads to energy consumption at induced draft fan to keep the incinerator on negative pressure, so that its proper control is important to operate incineration facility efficiently. The pressure drop at fabric filters decreased whenever phosphoric acid wastewater (PAW) was sprayed into an incinerator for treating industrial waste. Operational data obtained from the incineration facility were analyzed to determine the short- and long-term effects of PAW spraying on the pressure drop. For the short-term effect, it was confirmed that the pressure drop at the fabric filters always decreased to 0.3-1.2kPa within about 5h after spraying PAW. This effect was expected to be obtained by about one third of present PAW spraying amount. However, from the long-term perspective, the pressure drop showed an increase in the periods of PAW spraying compared with periods for which PAW spraying was not performed. The pressure drop increase was particularly noticeable after the initial PAW spraying, regardless of the age and type of fabric filters used. These results suggest that present PAW spraying causes a temporary pressure drop reduction, leading to short-term energy consumption savings; however, it also causes an increase of the pressure drop over the long-term, degrading the overall operating conditions. Thus, appropriate PAW spraying conditions are needed to make effective use of PAW to reduce the pressure drop at fabric filters from a short- and long-term point of view. PMID:27040089

  19. Microfluidic analysis of pressure drop and flow behavior in hypertensive micro vessels.

    PubMed

    Hu, Ruiqing; Li, Fen; Lv, Jiaqi; He, Ying; Lu, Detang; Yamada, Takashi; Ono, Naoki

    2015-01-01

    The retinal arterial network is the only source of the highly nutrient-consumptive retina, thus any insult on the arteries can impair the retinal oxygen and nutrient supply and affect its normal function. The aim of this work is to study the influences of vascular structure variation on the flow and pressure characteristics via microfluidic devices. Two sets of micro-channel were designed to mimic the stenosed microvessels and dichotomous branching structure in the retinal arteries. Three working fluids including red blood cell (RBC) suspension were employed to investigate the pressure drop in the stenosed channel. The flow behaviors of RBC suspensions inside the micro channels were observed using high speed camera system. Pressure drop of different working fluids and RBC velocity profiles in the stenosed channel were obtained. Moreover, hematocrit levels of RBC suspensions inside the bifurcated channels were analyzed from the sequential images of RBC flow. The results of the flow in the stenosed channel show that RBCs drift from the center of the channels, and RBC velocity is influenced not only by the inlet flow rate but also the interaction between RBCs. The measured pressure drops in the stenosed channel increase notably with the increase of fluid viscosity. Furthermore, the dimensionless pressure drop due to the stenosis decreases with Reynolds number. On the other hand, the results of flow through the bifurcated channels show that as the ratio of the daughter-branch width to the mother-channel width increases, the ratio of hematocrit in two connected branches (Ht/Hd) decreases, which is in favorable agreement with the available analysis results. PMID:26004808

  20. Analysis of single phase flow pressure drop and heat transfer in a horizontal rifled tube

    NASA Astrophysics Data System (ADS)

    Lam, Soo Poey; Wahab, Abas Abdul; Ariffin, Saparudin; Kiow, Lee Woon

    2012-06-01

    Analysis by using Fluent® has been carried out to investigate the pressure drop and heat transfer of single phase flow (Reynolds number ranging from 2.0×104 - 1.4×105) in a 2 meter long of rifled tube and smooth tube which are heated at the outer wall at constant temperature. The rifled tube or also known as spiral internally ribbed tube which is used in this investigation has an outside diameter 45.0 mm and inside equivalent diameter of 33.1 mm while the smooth tube has an outside diameter 45.0 mm and inside diameter 34.1 mm. The working fluid that is used in this investigation is water. In this analysis, realizable k-epsilon model has been chosen to solve the fully developed turbulence flow in both the tubes. The result from simulation shows that the pressure drop in rifled tube is about 1.69-2.0 times higher than in the smooth tube while the heat transfer coefficient of water in the rifle tube is 0.97-1.27 times than in the smooth tube. The high pressure drop and heat transfer coefficient in rifled tube comparing to smooth tube is due to the helical rib in the rifled tube which not only acted as rough surface, but also causes swirling effect near the wall which enhance heat transfer. The present study has proved that although the rifled tube produces high pressure drop but it is good in heat transfer enhancement through the ratio of heat flux to the pumping power. Correlations have been proposed for the single phase friction factor and Nusselt number of the rifled tube.

  1. 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.

  2. Equivalent particle diameter and length scale for pressure drop in porous metals

    SciTech Connect

    Dukhan, Nihad; Patel, Pragnesh

    2008-04-15

    The internal architecture of metal foam is significantly different from that of traditional porous media. This provides a set of challenges for understanding the fluid flow in this relatively new class of materials. This paper proposes that despite the geometrical differences between metal foam and traditional porous media, the Ergun correlation is a good fit for the linear pressure drop as a function of the Darcian velocity, provided that an appropriate equivalent particle diameter is used. The paper investigates an appropriate particle diameter considering the physics of energy dissipation, i.e. the viscous shear and the form drag. The above approach is supported by wind tunnel steady-state unidirectional pressure drop measurements for airflow through several isotropic open-cell aluminum foam samples having different porosities and pore densities. For each foam sample, the equivalent particle diameter correlated well with the surface area per unit volume of the foam. This was also very well valid for previous porous metal pressure drop data in the open literature. (author)

  3. Prediction of Frictional Pressure Drop During Water Permeation Through Packed Beds of Granular Particulates

    SciTech Connect

    KING, WILLIAM D.; ALEMAN, SEBASTIAN E.; HAMM, L. LARRY; PETTIS, MYRA A.

    2005-10-25

    A methodology has been developed based on the Kozeny-Carman equation to predict frictional pressure drops during water permeation of packed columns containing essentially noncompressible, but highly irregular particles. The resulting model accurately predicts pressure drop as a function of liquid flow rate and resin particle size for this system. A total of five particle sieve cuts across the range -20 to +70 mesh were utilized for testing using deionized water as the mobile phase. The Rosin-Rammler equation was used to fit the raw particle size data (wet sieve analysis) for the as-received resin sample and generate a continuous cumulative distribution function based on weight percent passing through the sieve. Probability distribution functions were calculated from the cumulative distribution for each particle sieve cut tested. Nine particle diameter definitions (i.e., number mean, volume mean, etc.) were then selected from the distribution function for each sample to represent the average spherically-equivalent particle diameter as input to the Kozeny-Carman equation. Nonlinear least squares optimization of the normalized pressure drop residuals were performed by parameter estimation of particle shape factor and bed porosity for all samples simultaneously using a given average particle diameter definition. Good fits to the full experimental data set were obtained when utilizing the number mean and the number median diameters. However, the shape factor and porosity values of 0.88 and 0.40, respectively, obtained from fitting the data using the number mean diameter were more consistent with experimental observations.

  4. Effects of sudden expansion and contraction flow on pressure drops in the Stirling engine regenerator

    SciTech Connect

    Hamaguchi, K.; Yamashita, I.; Hirata, K.

    1998-07-01

    The flow losses in the regenerators greatly influence the performance of the Stirling engine. The losses mainly depend on fluid friction through the regenerator matrix, but are also generated in sudden expansion and contraction flow at the regenerator ends. The latter losses can't be neglected in the case of small area ratio (entrance area/cross-sectional area in regenerator). The pressure drops in regenerators are usually estimated assuming a uniform velocity distribution of working gas in the matrices. The estimation results, however, are generally smaller than practical data. The cross-sectional flow areas of the heater and cooler of typical Stirling engines are smaller than the cross- sectional area of the regenerator. The effects of the small flow passage on the velocity distribution of working fluid in the matrix, that is, a flow transition from tubes or channels to a regenerator matrix, can be often confirmed by the discolored matrix. Especially, the lack of a uniform distribution of velocity in the matrix causes increased flow loss and decreased thermal performance. So, it is necessary to understand the quantitative effects of the sudden change in flow area at the regenerator ends on the velocity distribution and pressure drop. In this paper, using matrices made of stacks of wire screens, the effects of the entrance and exit areas and the length of the regenerator on pressure drops are examined by an unidirectional steady flow apparatus. The experimental data are arranged in an empirical equation. The lack of a uniformity of velocity distribution is visualized using smoke-wire methods. The empirical equation presented is applied to the estimation of pressure loss in an actual engine regenerator. The applicability of the equation is examined by comparison of estimated value with engine data in pressure loss.

  5. Theoretical analysis of pressure-drop type instabilities in an upflow boiling system with an exit restriction

    NASA Astrophysics Data System (ADS)

    Cao, L.; Kakaç, S.; Liu, H. T.; Sarma, P. K.

    In this work, two-phase flow pressure-drop type instabilities in an upflow boiling system are studied theoretically. Dynamic simulations of the pressure-drop type instabilities require the knowledge of the steady state characteristics of the system in terms of the pressure drop versus the mass flow rate. In a boiling system with an exit restriction at the outlet of the boiling channel, the pressure drop through the system concentrates at the exit restriction. Therefore, the correlation of the pressure drop of the two-phase mixture flowing through the exit restriction (i.e. a sharp-edged orifice) is essential in the calculation of the total pressure drop of the system. A model for the exit restriction is developed and compared with the experimental results covering a wide range of vapor quality with different heat inputs and inlet subcoolings. The drift-flux model is adopted to predict the steady state characteristics of the boiling system. The dynamic oscillations of the quasi-static pressure-drop type instabilities in the boiling system are simulated and good predictions of the system stability boundary and oscillatory characteristics are obtained when compared with the experimental results.

  6. Determination of the cathode and anode voltage drops in high power low-pressure amalgam lamps

    SciTech Connect

    Vasilyak, L. M.; Vasiliev, A. I. Kostyuchenko, S. V.; Sokolov, D. V.; Startsev, A. Yu.; Kudryavtsev, N. N.

    2011-12-15

    For the first time, cathode and anode drops of powerful low-pressure amalgam lamps were measured. The lamp discharge current is 3.2 A, discharge current frequency is 43 kHz, linear electric power is 2.4 W/cm. The method of determination of a cathode drop is based on the change of a lamp operating voltage at variation of the electrode filament current at constant discharge current. The total (cathode plus anode) drop of voltage was measured by other, independent ways. The maximum cathode fall is 10.8 V; the anode fall corresponding to the maximal cathode fall is 2.4 V. It is shown that in powerful low pressure amalgam lamps the anode fall makes a considerable contribution (in certain cases, the basic one) to heating of electrodes. Therefore, the anode fall cannot be neglected, at design an electrode and ballast of amalgam lamps with operating discharge current frequency of tens of kHz.

  7. Hereditary Neuropathy with Liability to Pressure Palsy: A Recurrent and Bilateral Foot Drop Case Report

    PubMed Central

    Flor-de-Lima, Filipa; Taipa, Ricardo; Melo-Pires, Manuel; Rodrigues, Maria Lurdes

    2013-01-01

    Hereditary neuropathy with liability to pressure palsy is characterized by acute, painless, recurrent mononeuropathies secondary to minor trauma or compression. A 16-year-old boy had the first episode of right foot drop after minor motorcycle accident. Electromyography revealed conduction block and slowing velocity conduction of the right deep peroneal nerve at the fibular head. After motor rehabilitation, he fully recovered. Six months later he had the second episode of foot drop in the opposite site after prolonged squatting position. Electromyography revealed sensorimotor polyneuropathy of left peroneal, sural, posterior tibial, and deep peroneal nerves and also of ulnar, radial, and median nerves of both upper limbs. Histological examination revealed sensory nerve demyelination and focal thickenings of myelin fibers. The diagnosis of hereditary neuropathy with liability to pressure palsy was confirmed by PMP22 deletion of chromosome 17p11.2. He started motor rehabilitation and avoidance of stressing factors with progressive recovery. After one-year followup, he was completely asymptomatic. Recurrent bilateral foot drop history, “sausage-like” swellings of myelin in histological examination, and the results of electromyography led the authors to consider the diagnosis despite negative family history. The authors highlight this rare disease in pediatric population and the importance of high index of clinical suspicion for its diagnosis. PMID:24251057

  8. Development of a new pressure dependent threshold superheated drop detector for neutrons

    NASA Astrophysics Data System (ADS)

    Rezaeian, Peiman; Raisali, Gholamreza; Akhavan, Azam; Ghods, Hossein; Hajizadeh, Bardia

    2015-03-01

    In this paper, a set of superheated drop detectors operated at different pressures is developed and fabricated by adding an appropriate amount of Freon-12 liquid on the free surface of the detector. The fabricated detectors have been used for determination of the threshold pressure for 2.89 MeV neutrons of a neutron generator in order to estimate the thermodynamic efficiency. Finally, knowing the thermodynamic efficiency of the detector and in a similar manner, the threshold pressure for 241Am-Be neutrons is determined and accordingly, the maximum neutron energy of the source spectrum is estimated. The maximum neutron energy of the 241Am-Be is estimated as 10.97±2.11 MeV. The agreement between this measured maximum energy and the reported value of the 241Am-Be neutron source shows that the method developed to apply pressure on the superheated drop detectors can be used to control the energy threshold of these detectors.

  9. Extraction of essential oils from Algerian myrtle leaves using instant controlled pressure drop technology.

    PubMed

    Berka-Zougali, Baya; Hassani, Aicha; Besombes, Colette; Allaf, Karim

    2010-10-01

    In the present work, the new extraction process of Détente Instantanée Contrôlée DIC (French, for instant controlled pressure drop) was studied, developed, quantitatively and qualitatively compared to the conventional hydrodistillation method for the extraction of essential oils from Algerian myrtle leaves. DIC was used as a thermomechanical treatment, DIC subjecting the product to a high-pressure saturated steam. The DIC cycle ends with an abrupt pressure drop towards vacuum, and this instantly leads to an autovaporization of myrtle volatile compounds. An immediate condensation in the vacuum tank produced a micro-emulsion of water and essential oils. Thus, an ultra-rapid cooling of residual leaves occurred, precluding any thermal degradation. An experimental protocol was designed with 3 independent variables: saturated steam pressure between 0.1 and 0.6 MPa, resulting in a temperature between 100 and 160°C, a total thermal processing time between 19 and 221 s, and between 2 and 6 DIC cycles. The essential oils yield was defined as the main dependent variable. This direct extraction gave high yields and high quality essential oil, as revealed by composition and antioxidant activity (results not shown). After this treatment, the myrtle leaves were recovered and hydrodistilled in order to quantify the essential oil content in residual DIC-treated samples. Scanning electron microscope (SEM) showed some modification of the structure with a slight destruction of cell walls after DIC treatment. PMID:20813373

  10. The influence of the equivalent hydraulic diameter on the pressure drop prediction of annular test section

    NASA Astrophysics Data System (ADS)

    Al-Kayiem, A. H. H.; Ibrahim, M. A.

    2015-12-01

    The flow behaviour and the pressure drop throughout an annular flow test section was investigated in order to evaluate and justify the reliability of experimental flow loop for wax deposition studies. The specific objective of the present paper is to assess and highlight the influence of the equivalent diameter method on the analysis of the hydrodynamic behaviour of the flow and the pressure drop throughout the annular test section. The test section has annular shape of 3 m length with three flow passages, namely; outer thermal control jacket, oil annular flow and inner pipe flow of a coolant. The oil annular flow has internal and external diameters of 0.0422 m and 0.0801 m, respectively. Oil was re-circulated in the annular passage while a cold water-glycol mixture was re-circulated in the inner pipe counter currently to the oil flow. The experiments were carried out at oil Reynolds number range of 2000 to 17000, covering laminar, transition and turbulent flow regimes. Four different methods of equivalent diameter of the annulus have been considered in this hydraulic analysis. The correction factor model for frictional pressure drop was also considered in the investigations. All methods addressed the high deviation of the prediction from the experimental data, which justified the need of a suitable pressure prediction correlation for the annular test section. The conventional hydraulic diameter method is a convenient substitute for characterizing physical dimension of a non-circular duct, and it leads to fairly good correlation between turbulent fluid flow and heat transfer characteristic of annular ducts.

  11. Evaluation of the models available for the prediction of pressure drop in venturi scrubbers.

    PubMed

    Gonçalves, J A; Alonso, D F; Costa, M A; Azzopardi, B J; Coury, J R

    2001-01-29

    The major running cost derived from the operation of venturi scrubbers is pressure drop. In the present study, the predictions of different models are compared to experimental data from venturi scrubbers of different sizes (throat diameter from 1.9 to 16cm), geometries, operating variables and liquid injection arrangements. As a result, it is concluded that most of the models must be used with caution. Much attention must be paid to the validity of the assumptions employed in the mathematical models. The equations proposed by Calvert [Scrubbing, Air Pollution, 3rd Edition, Vol. IV, Academic Press, New York, 1982], Yung et al. [JAPCA 27 (1977) 348] or Hesketh [Atomization and cloud behaviour in wet scrubbers, in: Proceedings of the US-USSR Symposium Control Fine Particulate Emissions 1974, San Francisco, 15-18 January 1974] produce good results only in very specific situations. The model proposed by Boll [Ind. Eng. Chem. Fundam. 12 (1973) 40] is simple, easy to compute and agrees reasonably well with the experimental data. Unfortunately, it cannot predict the effect of different liquid injection arrangements. The model by Azzopardi and coworkers [Filtr. Sep. 21 (1984) 196; Trans. IchemE. 69B (1991) 237; Chem Eng. J. 67 (1997) 9] was the only one to give good predictions for all the range of variables studied. On the other hand, this model is not simple and requires from the engineer an additional effort in terms of computation. In order to apply this model to the rectangular geometry, the concept of hydraulic equivalent diameter was used. PMID:11118688

  12. Numerical investigation of cavitation flow inside spool valve with large pressure drop

    NASA Astrophysics Data System (ADS)

    Deng, Jian; Pan, Dingyi; Xie, Fangfang; Shao, Xueming

    2015-12-01

    Spool valves play an important role in fluid power system. Cavitation phenomena happen frequently inside the spool valves, which cause structure damages, noise and lower down hydrodynamic performance. A numerical tools incorporating the cavitation model, are developed to predict the flow structure and cavitation pattern in the spool valve. Two major flow states in the spool valve chamber, i.e. flow-in and flow-out, are studies. The pressure distributions along the spool wall are first investigated, and the results agree well with the experimental data. For the flow-in cases, the local pressure at the throttling area drops much deeper than the pressure in flow-out cases. Meanwhile, the bubbles are more stable in flow-in cases than those in flow-out cases, which are ruptured and shed into the downstream.

  13. Impact of organic nutrient load on biomass accumulation, feed channel pressure drop increase and permeate flux decline in membrane systems.

    PubMed

    Bucs, Sz S; Valladares Linares, R; van Loosdrecht, M C M; Kruithof, J C; Vrouwenvelder, J S

    2014-12-15

    The influence of organic nutrient load on biomass accumulation (biofouling) and pressure drop development in membrane filtration systems was investigated. Nutrient load is the product of nutrient concentration and linear flow velocity. Biofouling - excessive growth of microbial biomass in membrane systems - hampers membrane performance. The influence of biodegradable organic nutrient load on biofouling was investigated at varying (i) crossflow velocity, (ii) nutrient concentration, (iii) shear, and (iv) feed spacer thickness. Experimental studies were performed with membrane fouling simulators (MFSs) containing a reverse osmosis (RO) membrane and a 31 mil thick feed spacer, commonly applied in practice in RO and nanofiltration (NF) spiral-wound membrane modules. Numerical modeling studies were done with identical feed spacer geometry differing in thickness (28, 31 and 34 mil). Additionally, experiments were done applying a forward osmosis (FO) membrane with varying spacer thickness (28, 31 and 34 mil), addressing the permeate flux decline and biofilm development. Assessed were the development of feed channel pressure drop (MFS studies), permeate flux (FO studies) and accumulated biomass amount measured by adenosine triphosphate (ATP) and total organic carbon (TOC). Our studies showed that the organic nutrient load determined the accumulated amount of biomass. The same amount of accumulated biomass was found at constant nutrient load irrespective of linear flow velocity, shear, and/or feed spacer thickness. The impact of the same amount of accumulated biomass on feed channel pressure drop and permeate flux was influenced by membrane process design and operational conditions. Reducing the nutrient load by pretreatment slowed-down the biofilm formation. The impact of accumulated biomass on membrane performance was reduced by applying a lower crossflow velocity and/or a thicker and/or a modified geometry feed spacer. The results indicate that cleanings can be delayed

  14. Predicting Equations for Evaporation Pressure Drop Inside Horizontal Smooth and Grooved Tubes

    NASA Astrophysics Data System (ADS)

    Kubota, Atsushi; Uchida, Mari; Shikazono, Naoki

    A new prediction method for evaporation pressure drop inside horizontal smooth and grooved tubes is proposed. These tubes had an outer diameter of 7mm, and the working fluids were R407C (HFC-32/HFC-125/HFC-134a, 23/25/52 mass%) and R410A (HFC-32/HFC-125, 50/50 mass%). The previous and present experimental data were correlated by Lockhart-Martinelli method, where Colburn and Carnavos equations were utilized for predicting single phase pressure drop of smooth and grooved tubes, respectively. Different numerical constants were adopted for smooth and grooved tubes to calculate the L-M pressure parameter φ L.Inorder to express the gravitational effect, a damping function for φ L was introduced. The proposed damping function was expressed as a function of Froude number for both smooth and grooved tubes. It is confirmed that 95% of the predicted results are within the accuracy of ±30% for both smooth and grooved tubes.

  15. Biobased extreme pressure additives: Structure-property considerations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extreme pressure additives are widely used in lubricant formulations for engine oils, hydraulic fluids, gear oils, metalworking fluids, and many others. Extreme pressure additives contain selected elements such as sulfur, phosphorus, and halogens in their structures. These elements, under extreme tr...

  16. Condensation pressure drop of R22, R134a and R410A in a single circular microtube

    NASA Astrophysics Data System (ADS)

    Son, Chang-Hyo; Oh, Hoo-Kyu

    2012-08-01

    The condensation pressure drop characteristics for pure refrigerants R22, R134a, and a binary refrigerant mixture R410A without lubricating oil in a single circular microtube were investigated experimentally. The test section consists of 1,220 mm length with horizontal copper tube of 3.38 mm outer diameter and 1.77 mm inner diameter. The experiments were conducted at refrigerant mass flux of 450-1,050 kg/m2s, and saturation temperature of 40°C. The main experimental results showed that the condensation pressure drop of R134a is higher than that of R22 and R410A for the same mass flux. The experimental data were compared against 14 two-phase pressure drop correlations. A new pressure drop model that is based on a superposition model for refrigerants condensing in the single circular tube is presented.

  17. The impact of mass flow and masking on the pressure drop of air filter in heavy-duty diesel engine

    NASA Astrophysics Data System (ADS)

    Hoseeinzadeh, Sepideh; Gorji-Bandpy, Mofid

    2012-04-01

    This paper presents a computational fluid dynamics (CFD) calculation approach to predict and evaluate the impact of the mass-flow inlet on the pressure drop of turbocharger`s air filtfer in heavy-duty diesel engine. The numerical computations were carried out using a commercial CFD program whereas the inlet area of the air filter consisted of several holes connected to a channel. After entering through the channel, the air passes among the holes and enters the air filter. The effect of masking holes and hydraulic diameter is studied and investigated on pressure drop. The results indicate that pressure drop increase with decreasing of hydraulic diameter and masking of the holes has considerable affect on the pressure drop.

  18. Analysis of MHD Pressure Drop in Liquid LiPb Flow in Chinese ITER DFLL-TBM with Insulating Coating

    NASA Astrophysics Data System (ADS)

    Chen, Hongli; Zhou, Tao; Wang, Hongyan

    2008-08-01

    Magnetohydrodynamic (MHD) pressure drop in the Chinese Dual Functional Liquid Lithium-lead Test Blanket Module (DFLL-TBM) proposed for ITER is discussed in this paper. Electrical insulation between the coolant channel surfaces and the liquid metal is required to reduce the MHD pressure drop to a manageable level. Insulation can be provided by a thin insulating coating, such as Al2O3, which can also serve as a tritium barrier layer, at the channel surfaces in contact with LiPb. The coating's effectiveness for reducing the MHD pressure drop is analysed through three-dimensional numerical simulation. A MHD-based commercial computational fluid dynamic (CFD) software FLUENT is used to simulate the LiPb flow. The effect on the MHD pressure drop due to cracks or faults in the coating layer is also considered. The insulating performance requirement for the coating material in DFLL-TBM design is proposed according to the analysis.

  19. Pressure drop considerations of a lithium cooled fusion breeder tokamak reactor blanket

    SciTech Connect

    Wong, C.P.C.

    1983-12-06

    Liquid lithium was selected as one of the coolants for the 1983 fusion breeder blanket used on the magnetically confined tokamak fusion reactor, and as a result, the thermal-hydraulic calculations were dominated by magnetohydrodynamic (MHD) considerations. The applicable sets of MHD equations for the engineering thermal-hydraulic design were reviewed and compared. Special attention was given to the MHD calculations for the fertile material zone, a packed bed of composite beryllium and thorium balls, since this region can dominate the thermal-hydraulic behavior of this blanket module. To keep the pressure drops acceptable, fertile fuel balls were omitted in the inboard blanket.

  20. Dysfunctional vestibular system causes a blood pressure drop in astronauts returning from space

    PubMed Central

    Hallgren, Emma; Migeotte, Pierre-François; Kornilova, Ludmila; Delière, Quentin; Fransen, Erik; Glukhikh, Dmitrii; Moore, Steven T.; Clément, Gilles; Diedrich, André; MacDougall, Hamish; Wuyts, Floris L.

    2015-01-01

    It is a challenge for the human body to maintain stable blood pressure while standing. The body’s failure to do so can lead to dizziness or even fainting. For decades it has been postulated that the vestibular organ can prevent a drop in pressure during a position change – supposedly mediated by reflexes to the cardiovascular system. We show – for the first time – a significant correlation between decreased functionality of the vestibular otolith system and a decrease in the mean arterial pressure when a person stands up. Until now, no experiments on Earth could selectively suppress both otolith systems; astronauts returning from space are a unique group of subjects in this regard. Their otolith systems are being temporarily disturbed and at the same time they often suffer from blood pressure instability. In our study, we observed the functioning of both the otolith and the cardiovascular system of the astronauts before and after spaceflight. Our finding indicates that an intact otolith system plays an important role in preventing blood pressure instability during orthostatic challenges. Our finding not only has important implications for human space exploration; they may also improve the treatment of unstable blood pressure here on Earth. PMID:26671177

  1. Dysfunctional vestibular system causes a blood pressure drop in astronauts returning from space.

    PubMed

    Hallgren, Emma; Migeotte, Pierre-François; Kornilova, Ludmila; Delière, Quentin; Fransen, Erik; Glukhikh, Dmitrii; Moore, Steven T; Clément, Gilles; Diedrich, André; MacDougall, Hamish; Wuyts, Floris L

    2015-01-01

    It is a challenge for the human body to maintain stable blood pressure while standing. The body's failure to do so can lead to dizziness or even fainting. For decades it has been postulated that the vestibular organ can prevent a drop in pressure during a position change--supposedly mediated by reflexes to the cardiovascular system. We show--for the first time--a significant correlation between decreased functionality of the vestibular otolith system and a decrease in the mean arterial pressure when a person stands up. Until now, no experiments on Earth could selectively suppress both otolith systems; astronauts returning from space are a unique group of subjects in this regard. Their otolith systems are being temporarily disturbed and at the same time they often suffer from blood pressure instability. In our study, we observed the functioning of both the otolith and the cardiovascular system of the astronauts before and after spaceflight. Our finding indicates that an intact otolith system plays an important role in preventing blood pressure instability during orthostatic challenges. Our finding not only has important implications for human space exploration; they may also improve the treatment of unstable blood pressure here on Earth. PMID:26671177

  2. Clinical outcomes of combined flow-pressure drop measurements using newly developed diagnostic endpoint: Pressure drop coefficient in patients with coronary artery dysfunction

    PubMed Central

    Effat, Mohamed A; Peelukhana, Srikara Viswanath; Banerjee, Rupak K

    2016-01-01

    AIM: To combine pressure and flow parameter, pressure drop coefficient (CDP) will result in better clinical outcomes in comparison to the fractional flow reserve (FFR) group. METHODS: To test this hypothesis, a comparison was made between the FFR < 0.75 and CDP > 27.9 groups in this study, for the major adverse cardiac events [major adverse cardiac events (MACE): Primary outcome] and patients’ quality of life (secondary outcome). Further, a comparison was also made between the survival curves for the FFR < 0.75 and CDP > 27.9 groups. Two-tailed χ2 test proportions were performed for the comparison of primary and secondary outcomes. Kaplan-Meier survival analysis was performed to compare the survival curves of FFR < 0.75 and CDP > 27.9 groups (MedcalcV10.2, Mariakerke, Belgium). Results were considered statistically significant for P < 0.05. RESULTS: The primary outcomes (%MACE) in the FFR < 0.75 group (20%, 4 out of 20) was not statistically different (P = 0.24) from the %MACE occurring in CDP > 27.9 group (8.57%, 2 out of 35). Noteworthy is the reduction in the %MACE in the CDP > 27.9 group, in comparison to the FFR < 0.75 group. Further, the secondary outcomes were not statistically significant between the FFR < 0.75 and CDP > 27.9 groups. Survival analysis results suggest that the survival time for the CDP > 27.9 group (n = 35) is significantly higher (P = 0.048) in comparison to the survival time for the FFR < 0.75 group (n = 20). The results remained similar for a FFR = 0.80 cut-off. CONCLUSION: Based on the above, CDP could prove to be a better diagnostic end-point for clinical revascularization decision-making in the cardiac catheterization laboratories. PMID:27022460

  3. Effects of slitted fins on the heat transfer and pressure drop characteristics of a compact heat exchanger

    SciTech Connect

    Kim, C.H.; Yun, J.Y.

    1996-12-31

    A compact heat exchanger which consists of air-cooled aluminum fins and copper tubes circulating refrigerant has been used in a cooling system for a long time. There are two key parameters to be seriously considered for a design of the heat exchanger and its performance improvement. These are the heat transfer rate and pressure drop coefficient which varies with the change of the tube size, its arrangement and the fin configuration. In here, a numerical study was carried to understand the effect of the fin configuration on the heat transfer and pressure drop of the heat exchanger. The diameter and the arrangement of tubes were fixed but three different types of the fin configuration were used to see its effect on the heat transfer capacity and the static pressure drop. The calculation results were compared with that of a flat plate fin. From the comparison, it was found that the slitted fins have higher pressure drop; however, they have higher heat transfer rate. It means that the simpler of the fin configuration, the lower pressure drop and heat transfer coefficients are obtained. It is mainly due to the discretisation of the thermal boundary layer on the fin surface to maximize the heat transfer to air. The slitted sides of fins act like obstacles in the airflow path. From the experimental result, it was found that the same trend in the variation of the heat transfer rate and the pressure drop with the change of the fin configuration was obtained.

  4. Prediction of two-phase pressure drop in heat exchanger for mixed refrigerant Joule-Thomson cryocooler

    NASA Astrophysics Data System (ADS)

    Ardhapurkar, P. M.; Atrey, M. D.

    2015-12-01

    The overall efficiency of a mixed refrigerant Joule-Thomson (MR J-T) cryocooler is governed by the performance of the recuperative heat exchanger. In the heat exchanger, the hot stream of the mixed refrigerant undergoes condensation at high pressure while the cold stream gets evaporated at low pressure. The pressure drop in the low pressure stream is crucial since it directly influences the achievable refrigeration temperature. However, experimental and theoretical studies related to two-phase pressure drop in mixtures at cryogenic temperatures, are limited. Therefore, the design of an efficient MR J-T cryocooler is a challenging task due to the lack of predictive tools. In the present work, the existing empirical correlations, which are commonly used for the prediction of pressure drop in the case of pure refrigerants, evaporating at near ambient conditions, are assessed for the mixed refrigerants. Experiments are carried out to measure the overall pressure drop in the evaporating cold stream of the tube-in-tube helically coiled heat exchanger. The predicted frictional pressure drop in the heat exchanger is compared with the experimental data. The suggested empirical correlations can be used to predict the hydraulic performance of the heat exchanger.

  5. 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.

  6. Hereditary neuropathy with liability to pressure palsy presenting with hand drop in a young child.

    PubMed

    Sobreira, Inês; Sousa, Cátia; Raposo, Ana; Soares, M Rita; Soudo, Ana; Dias, Ana Isabel

    2012-01-01

    Hereditary neuropathy with liability to pressure palsy (HNPP) results from the deletion of the PMP22 gene in chromosome 17p11.2. Clinically, it presents with painless pressure palsies, typically in the 2nd and 3rd decades of life, being a rare entity in childhood. We present the case study of a six-year-old male child who presented with left hand drop that he kept for over four weeks. Electrophysiological studies suggested HNPP and genetic studies confirmed it. With this paper, we pretend to create awareness to this entity as a diagnosis to be considered in a child with painless monoparesis and to emphasize the importance of electrophysiological studies in the diagnosis. PMID:22953141

  7. Hereditary Neuropathy with Liability to Pressure Palsy Presenting with Hand Drop in a Young Child

    PubMed Central

    Sobreira, Inês; Sousa, Cátia; Raposo, Ana; Soares, M. Rita; Soudo, Ana; Dias, Ana Isabel

    2012-01-01

    Hereditary neuropathy with liability to pressure palsy (HNPP) results from the deletion of the PMP22 gene in chromosome 17p11.2. Clinically, it presents with painless pressure palsies, typically in the 2nd and 3rd decades of life, being a rare entity in childhood. We present the case study of a six-year-old male child who presented with left hand drop that he kept for over four weeks. Electrophysiological studies suggested HNPP and genetic studies confirmed it. With this paper, we pretend to create awareness to this entity as a diagnosis to be considered in a child with painless monoparesis and to emphasize the importance of electrophysiological studies in the diagnosis. PMID:22953141

  8. Pressure Drop in Tortuosity/Kinking of the Internal Carotid Artery: Simulation and Clinical Investigation

    PubMed Central

    Wang, Lijun; Zhao, Feng; Wang, Daming; Hu, Shen; Liu, Jiachun; Zhou, Zhilun; Lu, Jun; Qi, Peng; Song, Shiying

    2016-01-01

    Background. Whether carotid tortuosity/kinking of the internal carotid artery leads to cerebral ischemia remains unclear. There is very little research about the hemodynamic variation induced by carotid tortuosity/kinking in the literature. The objective of this study was to research the blood pressure changes induced by carotid tortuosity/kinking. Methods. We first created a geometric model of carotid tortuosity/kinking. Based on hemodynamic boundary conditions, the hemodynamics of carotid tortuosity and kinking were studied via a finite element simulation. Then, an in vitro system was built to validate the numerical simulation results. The mean arterial pressure changes before and after carotid kinking were measured using pressure sensors in 12 patients with carotid kinking. Results. Numerical simulation revealed that the pressure drops increased with increases in the kinking angles. Clinical tests and in vitro experiments confirmed the numerical simulation results. Conclusions. Carotid kinking leads to blood pressure reduction. In certain conditions, kinking may affect the cerebral blood supply and be associated with cerebral ischemia. PMID:27195283

  9. Heat transfer and pressure drop characteristic of zinc-water nanofluid

    NASA Astrophysics Data System (ADS)

    Sonage, B. K.; Mohanan, P.

    2015-04-01

    Development of alternative working fluids with enhanced thermal properties is very much needed to replace conventional fluids. Colloidal solution of some base fluid with solid nanoparticles dispersed in it, which is called as nanofluid, is emerging as a promising alternative heat transfer fluid. Zinc, being ecofriendly material, is selected as dispersed phase in water to develop zinc-water (Zn-H2O) nanofluid. Zn-H2O nanofluid is synthesized by single step method and characterized. Thermophysical properties are estimated by available theoretical models. Estimated properties proved that nanofluid is having enhanced thermophysical properties compared to the base fluid due to which nanofluid can become potential working fluid for heat exchanging devices. Synthesized nanofluid is circulated through heat transfer loop to assess its performance in turbulent flow regime and at constant wall temperature condition. Heat transfer coefficient and pressure drop are estimated from experimental results and both are considered as performance evaluation criteria for heat transfer performance assessment. 83 % increase in Nusselt number with 9 % increase in pressure drop is observed for the nanofluid compared to water.

  10. Pressure Drop Correlations of Single-Phase and Two-Phase Flow in Rolling Tubes

    SciTech Connect

    Xia-xin Cao; Chang-qi Yan; Pu-zhen Gao; Zhong-ning Sun

    2006-07-01

    A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than {+-} 25%. (authors)

  11. Heat transfer and pressure drop in an annular channel with downflow

    SciTech Connect

    Dolan, F.X.; Crowley, C.J.; Qureshi, Z.H.

    1992-06-01

    The onset of a flow instability (OFI) determines the minimum flow rate for cooling in the flow channels of a nuclear fuel assembly. A test facility was constructed with full-scale models (length and diameter) of annular flow channels incorporating many instruments to measure heat transfer and pressure drop with downflow in the annulus. Tests were performed both with and without axial centering ribs at prototypical values of pressure, flow rate and uniform wall heat flux. The axial ribs have the effect of subdividing the annulus into quadrants, so the problem becomes one of parallel channel flow, unlike previous experiments in tubes (upflow and downflow). Other tests were performed to determine the effects if any of asymmetric and non-uniform circumferential wall heating, operating pressure level and dissolved gas concentration. Data from the tests are compared with models for channel heat transfer and pressure drop profiles in several regimes of wall heating from single-phase forced convection through partially and fully developed nucleate boiling. Minimum stable flow rates were experimentally determined as a function of wall heat flux and heat distribution and compared with the model for the transition to fully developed boiling which is a key criterion in determining the OFI condition in the channel. The heat transfer results in the channel without ribs are in excellent agreement with predictions from a computer model of the flow in the annulus and with empirical correlations developed from similar tests. The test results with centering ribs show that geometrical variations between the channels can lead to differences in subchannel behavior which can make the effect of the ribs and the geometry an important factor when assessing the power level at which the fuel assembly (and the reactor) can be operated to prevent overheating in the event of a loss-of-coolant-accident (LOCA).

  12. Heat transfer and pressure drop in an annular channel with downflow

    SciTech Connect

    Dolan, F.X.; Crowley, C.J. ); Qureshi, Z.H. )

    1992-01-01

    The onset of a flow instability (OFI) determines the minimum flow rate for cooling in the flow channels of a nuclear fuel assembly. A test facility was constructed with full-scale models (length and diameter) of annular flow channels incorporating many instruments to measure heat transfer and pressure drop with downflow in the annulus. Tests were performed both with and without axial centering ribs at prototypical values of pressure, flow rate and uniform wall heat flux. The axial ribs have the effect of subdividing the annulus into quadrants, so the problem becomes one of parallel channel flow, unlike previous experiments in tubes (upflow and downflow). Other tests were performed to determine the effects if any of asymmetric and non-uniform circumferential wall heating, operating pressure level and dissolved gas concentration. Data from the tests are compared with models for channel heat transfer and pressure drop profiles in several regimes of wall heating from single-phase forced convection through partially and fully developed nucleate boiling. Minimum stable flow rates were experimentally determined as a function of wall heat flux and heat distribution and compared with the model for the transition to fully developed boiling which is a key criterion in determining the OFI condition in the channel. The heat transfer results in the channel without ribs are in excellent agreement with predictions from a computer model of the flow in the annulus and with empirical correlations developed from similar tests. The test results with centering ribs show that geometrical variations between the channels can lead to differences in subchannel behavior which can make the effect of the ribs and the geometry an important factor when assessing the power level at which the fuel assembly (and the reactor) can be operated to prevent overheating in the event of a loss-of-coolant-accident (LOCA).

  13. Heat transfer and pressure drop in an annular channel with downflow

    NASA Astrophysics Data System (ADS)

    Dolan, F. X.; Crowley, C. J.; Qureshi, Z. H.

    The onset of a flow instability (OFI) determines the minimum flow rate for cooling in the flow channels of a nuclear fuel assembly. A test facility was constructed with full-scale models (length and diameter) of annular flow channels incorporating many instruments to measure heat transfer and pressure drop with downflow in the annulus. Tests were performed both with and without axial centering ribs at prototypical values of pressure, flow rate and uniform wall heat flux. The axial ribs have the effect of subdividing the annulus into quadrants, so the problem becomes one of parallel channel flow, unlike previous experiments in tubes (upflow and downflow). Other tests were performed to determine the effects if any of asymmetric and non-uniform circumferential wall heating, operating pressure level and dissolved gas concentration. Data from the tests are compared with models for channel heat transfer and pressure drop profiles in several regimes of wall heating from single-phase forced convection through partially and fully developed nucleate boiling. Minimum stable flow rates were experimentally determined as a function of wall heat flux and heat distribution and compared with the model for the transition to fully developed boiling which is a key criterion in determining the OFI condition in the channel. The heat transfer results in the channel without ribs are in excellent agreement with predictions from a computer model of the flow in the annulus and with empirical correlations developed from similar tests. The test results with centering ribs show that geometrical variations between the channels can lead to differences in subchannel behavior which can make the effect of the ribs and the geometry an important factor when assessing the power level at which the fuel assembly (and the reactor) can be operated to prevent overheating in the event of a loss-of-coolant-accident (LOCA).

  14. Transient integral boundary layer method to calculate the translesional pressure drop and the fractional flow reserve in myocardial bridges

    PubMed Central

    Bernhard, Stefan; Möhlenkamp, Stefan; Tilgner, Andreas

    2006-01-01

    during re-opening of the vessel in diastole. We have further calculated the wall shear stress (WSS) distributions in addition to the location and length of the flow reversal zones in dependence on the severity of the disease. Conclusion The described boundary layer method can be used to simulate frictional forces and wall shear stresses in the entrance region of vessels. Earlier models are supplemented by the viscous effects in a quasi three-dimensional vessel geometry with a prescribed wall motion. The results indicate that the translesional pressure drop and the mean FFR compares favourably to clinical findings in the literature. We have further shown that the mean FFR under the assumption of Hagen-Poiseuille flow is overestimated in developing flow conditions. PMID:16790065

  15. Workplace field testing of the pressure drop of particulate respirators using welding fumes.

    PubMed

    Cho, Hyun-Woo; Yoon, Chung-Sik

    2012-10-01

    In a previous study, we concluded that respirator testing with a sodium chloride aerosol gave a conservative estimate of filter penetration for welding fume aerosols. A rapid increase in the pressure drop (PD) of some respirators was observed as fumes accumulated on the filters. The present study evaluated particulate respirator PD based on workplace field tests. A field PD tester was designed and validated using the TSI 8130 Automatic Filter Tester, designed in compliance with National Institute for Occupational and Safety and Health regulation 42 CFR part 84. Three models (two replaceable dual-type filters and one replaceable single-type filter) were evaluated against CO(2) gas arc welding on mild steel in confined booths in the workplace. Field tests were performed under four airborne concentrations (27.5, 15.4, 7.9, and 2.1 mg m(-3)). The mass concentration was measured by the gravimetric method, and number concentration was monitored using P-Trak (Model 8525, TSI, USA). Additionally, photos and scanning electron microscopy-energy dispersive X-ray spectroscopy were used to visualize and analyze the composition of welding fumes trapped in the filters. The field PD tester showed no significant difference compared with the TSI tester. There was no significant difference in the initial PD between laboratory and field results. The PD increased as a function of fume load on the respirator filters for all tested models. The increasing PD trend differed by models, and PD increased rapidly at high concentrations because greater amount of fumes accumulated on the filters in a given time. The increase in PD as a function of fume load on the filters showed a similar pattern as fume load varied for a particular model, but different patterns were observed for different models. Images and elemental analyses of fumes trapped on the respirator filters showed that most welding fumes were trapped within the first layer, outer web cover, and second layer, in order, while no fumes

  16. Characterization of surface roughness effects on pressure drop in single-phase flow in minichannels

    NASA Astrophysics Data System (ADS)

    Kandlikar, Satish G.; Schmitt, Derek; Carrano, Andres L.; Taylor, James B.

    2005-10-01

    Roughness features on the walls of a channel wall affect the pressure drop of a fluid flowing through that channel. This roughness effect can be described by (i) flow area constriction and (ii) increase in the wall shear stress. Replotting the Moody's friction factor chart with the constricted flow diameter results in a simplified plot and yields a single asymptotic value of friction factor for relative roughness values of ɛ /D>0.03 in the fully developed turbulent region. After reviewing the literature, three new roughness parameters are proposed (maximum profile peak height Rp, mean spacing of profile irregularities RSm, and floor distance to mean line Fp). Three additional parameters are presented to consider the localized hydraulic diameter variation (maximum, minimum, and average) in future work. The roughness ɛ is then defined as Rp+Fp. This definition yields the same value of roughness as obtained from the sand-grain roughness [H. Darcy, Recherches Experimentales Relatives au Mouvement de L'Eau dans les Tuyaux (Mallet-Bachelier, Paris, France, 1857); J. T. Fanning, A Practical Treatise on Hydraulic and Water Supply Engineering (Van Nostrand, New York, 1877, revised ed. 1886); J. Nikuradse, "Laws of flow in rough pipes" ["Stromungsgesetze in Rauen Rohren," VDI-Forschungsheft 361 (1933)]; Beilage zu "Forschung auf dem Gebiete des Ingenieurwesens," Ausgabe B Band 4, English translation NACA Tech. Mem. 1292 (1937)]. Specific experiments are conducted using parallel sawtooth ridge elements, placed normal to the flow direction, in aligned and offset configurations in a 10.03mm wide rectangular channel with variable gap (resulting hydraulic diameters of 325μm-1819μm with Reynolds numbers ranging from 200 to 7200 for air and 200 to 5700 for water). The use of constricted flow diameter extends the applicability of the laminar friction factor equations to relative roughness values (sawtooth height) up to 14%. In the turbulent region, the aligned and offset

  17. Base Oil-Extreme Pressure Additive Synergy in Lubricants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extreme pressure (EP) additives are those containing reactive elements such as sulfur, phosphorus, and chlorine. In lubrication processes that occur under extremely severe conditions (e.g., high pressure and/or slow speed), these elements undergo chemical reactions generating new materials (tribofi...

  18. An improved method for simultaneous determination of frictional pressure drop and vapor volume fraction in vertical flow boiling

    NASA Technical Reports Server (NTRS)

    Klausner, J. F.; Chao, B. T.; Soo, S. L.

    1990-01-01

    The two-phase frictional pressure drop and vapor volume fraction in the vertical boiling and adiabatic flow of the refrigerant, R11, have been simultaneously measured by a liquid balancing column and differential magnetic reluctance pressure transducers. An account is given of the experimental apparatus and procedure, data acquisition and analysis, and error estimation employed. All values of two-phase multipliers evaluated on the basis of the measured frictional pressure drop data in vertical upflow fall in the range bounded by the predictions of the Chisholm correlation and the homogeneous model.

  19. Pressure Drop Characteristics in Tight-Lattice Bundles for Reduced-Moderation Water Reactors

    NASA Astrophysics Data System (ADS)

    Tamai, Hidesada; Kureta, Masatoshi; Yoshida, Hiroyuki; Akimoto, Hajime

    The reduced-moderation water reactor (RMWR) consists of several distinctive structures; a triangular tight-lattice configuration and a double-flat core. In order to design the RMWR core from the point of view of thermal-hydraulics, an evaluation method on pressure drop characteristics in the rod bundles at the tight-lattice configuration is required. In this study, calculated results by the Martinelli-Nelson's and Hancox's correlations were compared with experimental results in 4×5 rod bundles and seven-rod bundles. Consequently, the friction loss in two-phase flows becomes smaller at the tight-lattice configuration with the hydraulic diameter less than about 3mm. This reason is due to the difference of the configuration between the multi-rod bundle and the circular tube and due to the effect of the small hydraulic diameter on the two-phase multiplier.

  20. Pressure drop and heat transfer for spirally fluted tubes including validation of the role of transition

    SciTech Connect

    Obot, N.T.; Esen, E.B.; Snell, K.H. . Fluid Mechanics, Heat and Mass Transfer Lab.); Rabas, T.J. )

    1991-01-01

    An experimental investigation was carried out to determine the pressure drop and heat transfer characteristics for spirally fluted tubes in laminar, transitional and turbulent flow of air. It is established that, in the laminar, transitional and turbulent regimes, the friction factor for the spirally fluted tube is generally higher than that for a smooth tube. The values for the critical Reynolds number at the onset of transition to turbulent flow are lower, while the corresponding critical friction factors are higher, than those for a smooth tube. Consistent with the expected effect of transition on heat transfer, the experimentally determined Nusselt numbers are generally higher than the smooth tube values. The results indicate that there is a definite connection between transition and the heat transfer enhancement. 10 refs., 11 figs.

  1. Pressure drop and heat transfer characteristics of circular and oblong low aspect ratio pin fins

    NASA Astrophysics Data System (ADS)

    Arora, S. C.; Messeh, W. A.

    1985-09-01

    The pressure drop and heat transfer characteristics of circular and oblong pin fins of height-to-diameter ratio of unity used to augment internal cooling of gas turbine airfoils are presented. Data were obtained for an array of 10 rows of staggered pin fins in a 25:1 aspect ratio channel, with both pins and channel endwalls forming the heat transfer surface. Results show that the array average friction factor increases with increasing blockage caused by different arrangement of pin fin geometries in the channel. The local heat transfer coefficient increases up to the 3rd row of pin fins and decreases thereafter. Oblong pin fins with gamma=90 deg (major axis parallel to the direction of flow) result in higher heat transfer rates and lower friction factor than the circular pin fins. For other orientations, oblong pin fins do not offer any advantage over circular pin fins for Re or = 20,000 (typical of small gas turbine engines).

  2. Preliminary investigation of labyrinth packing pressure drops at onset of swirl-induced rotor instability

    NASA Technical Reports Server (NTRS)

    Miller, E. H.; Vohr, J. H.

    1984-01-01

    Backward and forward subsynchronous instability was observed in a flexible model test rotor under the influence of swirl flow in a straight-through labyrinth packing. The packing pressure drop at the onset of instability was then measured for a range of operating speeds, clearances and inlet swirl conditions. The trend in these measurements for forward swirl and forward instability is generally consistent with the short packing rotor force formulations of Benchert and Wachter. Diverging clearances were also destabilizing and had a forward orbit with forward swirl and a backward orbit with reverse swirl. A larger, stiff rotor model system is now being assembled which will permit testing steam turbine-type straight-through and hi-lo labyrinth packings. With calibrated and adjustable bearings in this new apparatus, direct measure of the net destabilizing force generated by the packings can be made.

  3. Some flow characteristics of conventional and tapered high pressure drop simulated seals

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.

    1979-01-01

    The leak rates through shaft seals with large pressure drops were simulated using gaseous hydrogen, or nitrogen flowing through an annulus with a nonrotating centerbody. The flows were choked. For concentric or eccentric position of the rotor and parallel or convergent tapered flow passages, data and analysis revealed that mass flux or leak rate can be determined from a relation whose normalizing parameters depend on the thermodynamic critical constants of the working fluid and an average flow area expressed in terms of the inlet and exit cross-sectional areas. Using these normalized relations, the flow data for parallel and three convergent tapered shaft seal configurations are in good agreement. Generalization to any simple gas or gas mixture is implied and demonstrated.

  4. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Downward in a Small Diameter Tube

    NASA Astrophysics Data System (ADS)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    Experiments were performed on boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically downward in a copper smooth tube of 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and quality from 0.1 to over 1 at evaporation temperature of 10°C. Pressure drops were measured and flow patterns were observed at mass fluxes from 30 to 200 kg/(m2•s) and quality from 0.1 to 0.9. The characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified by comparing the measurements with the data for the vertically upward flow previously obtained.

  5. Modeling and experimental validation on pressure drop in a reverse-flow cyclone separator at high inlet solid loading

    NASA Astrophysics Data System (ADS)

    Wu, Xuezhi; Liu, Jie; Xu, Xiang; Xiao, Yunhan

    2011-08-01

    High inlet solid loading is one of the most important features of cyclone separators in high density circulating fluidized beds (CFB). In this work, the effect of high solid loading on pressure drop in a reverse-flow cyclone was experimentally studied. The particles used were sand and γ-Al2O3. An extended range of inlet solid loadings ( M), up to 30 kg of solids/ kg of air was tested at different inlet air velocities ( V in=16˜24 m/s), well beyond the solid loading range reported before. The experiments showed that, in the tested range of solid loadings, the cyclone pressure drop decreased dramatically with increasing solid loading when M<7.5 kg/kg and then almost remained constant. A new semi-empirical model for predicting cyclone pressure drop was also developed. The calculated and experimental results showed good agreement for particle free flow and particle laden flow.

  6. Experimental study on the flow patterns and the two-phase pressure drops in a horizontal impacting T-Junction

    NASA Astrophysics Data System (ADS)

    Bertani, C.; Malandrone, M.; Panella, B.

    2014-04-01

    The present paper analyzes the experimental results concerning the flow patterns and pressure drops in two-phase flow through a horizontal impacting T-junction, whose outlet pipes are aligned and perpendicular to the inlet pipe. The test section consists of plexiglass pipes with inner diameter of 10 mm. A mixture of water and air at ambient temperature and pressures up to 2.4 bar flows through the T-junction, with different splitting of flow rates in the two outlet branches; superficial velocities of air and water in the inlet pipe have been varied up to a maximum of 35 m/s and 3.5 m/s respectively. The flow patterns occurring in the inlet and branch pipes are compared with the predictions of the Baker and Taitel - Dukler maps. The pressure drops along the branches have been measured relatively to different splitting of the flow rate through the two branches and the pressure loss coefficients in the junction have been evaluated. Friction pressure drops have allowed us to evaluate two-phase friction multipliers, which have then been compared to the predictions of Lockhart-Martinelli, and Friedel correlations. Local pressure drops have been extrapolated at the junction centre and analyzed; the two-phase multiplier has been evaluated and compared with the predictions of Chisholm correlation; the value of the empirical coefficient that minimizes the discrepancy has also been evaluated.

  7. Decomposition of pilocarpine eye drops assessed by a highly efficient high pressure liquid chromatographic method.

    PubMed

    Kuks, P F; Weekers, L E; Goldhoorn, P B

    1990-10-19

    A rapid high-resolution high pressure liquid chromatographic method was developed for assaying pilocarpine. Pilocarpine in ophthalmic solutions decomposes fairly rapidly to give isopilocarpine, pilocarpic acid and isopilocarpic acid. The quality of an ophthalmic solution can be assessed by assaying these decomposition products. Existing high pressure liquid chromatographic methods suffer from long analysis times and poor resolution. The new method uses as the mobile phase 6 ml/l of triethylamine in water (pH 2.3, adjusted with 85% phosphoric acid) at a flow of 1.5 ml/min and as the stationary phase a C18-silica 125 x 4.6 mm column. 2-Amino-1-phenyl-1,3-propanediol is used as an internal standard. Complete separation was obtained within 8 min. Pilocarpine eye drops were stored under different conditions and then analysed for decomposition products. During heat treatment, decomposition to isopilocarpine predominated over decomposition to pilocarpic or isopilocarpic acid. However, when stored at room temperature or in a refrigerator, formation of pilocarpic acid clearly prevailed. Thus, from assessment of decomposition products, the cause of decomposition can be established. PMID:2255589

  8. High-Pressure Transport Properties Of Fluids: Theory And Data From Levitated Drops At Combustion-Relevant Temperatures

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Harstad, Kenneth; Ohsaka, Kenichi

    2003-01-01

    Although the high pressure multicomponent fluid conservation equations have already been derived and approximately validated for binary mixtures by this PI, the validation of the multicomponent theory is hampered by the lack of existing mixing rules for property calculations. Classical gas dynamics theory can provide property mixing-rules at low pressures exclusively. While thermal conductivity and viscosity high-pressure mixing rules have been documented in the literature, there is no such equivalent for the diffusion coefficients and the thermal diffusion factors. The primary goal of this investigation is to extend the low pressure mixing rule theory to high pressures and validate the new theory with experimental data from levitated single drops. The two properties that will be addressed are the diffusion coefficients and the thermal diffusion factors. To validate/determine the property calculations, ground-based experiments from levitated drops are being conducted.

  9. Numerical simulation of flow and the effect of baffle arrangement on pressure drop and temperature pattern in a circular combustor

    NASA Astrophysics Data System (ADS)

    Ghorashi, Bahman; Taruvai, Sastry

    A numerical simulation study was conducted to determine the effect of baffle arrangement on pressure drop in an experimental reverse-flow circular combustor with several mini-combustion zones (MCZ). The fluent computer code developed by Creare Inc., was used for this study. Three parameters which appeared to significantly affect the pressure drop were varied, and pressure drop for each case was numerically determined. The portion of the combustor volume that was investigated had two baffles on the upper face and two baffles on the lower face. Heated air at 1000 F with an inlet air velocity of 100 ft/sec and 1 atmosphere pressure was introduced into the combustor. Fuel (pentane) at 80 F was introduced via nozzles which were placed between the baffles. The following changes were then made in the baffle arrangement and the effects on the pressure drop and temperature distribution were evaluated for each of the following cases: (1) the positions of the baffles on the upper and lower face were changed; (2) the dimensions of the baffles were varied; (3) the shapes of the baffles were altered. The effects of the above mentioned design alterations are summarized.

  10. Study of Critical Heat Flux and Two-Phase Pressure Drop Under Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Abdollahian, Davood; Quintal, Joseph; Barez, Fred; Zahm, Jennifer; Lohr, Victor

    1996-01-01

    The design of the two-phase flow systems which are anticipated to be utilized in future spacecraft thermal management systems requires a knowledge of two-phase flow and heat transfer phenomena in reduced gravities. This program was funded by NASA headquarters in response to NRA-91-OSSA-17 and was managed by Lewis Research Center. The main objective of this program was to design and construct a two-phase test loop, and perform a series of normal gravity and aircraft trajectory experiments to study the effect of gravity on the Critical Heat Flux (CHF) and onset of instability. The test loop was packaged on two aircraft racks and was also instrumented to generate data for two-phase pressure drop. The normal gravity tests were performed with vertical up and downflow configurations to bound the effect of gravity on the test parameters. One set of aircraft trajectory tests was performed aboard the NASA DC-9 aircraft. These tests were mainly intended to evaluate the test loop and its operational performance under actual reduced gravity conditions, and to produce preliminary data for the test parameters. The test results were used to demonstrate the applicability of the normal gravity models for prediction of the two-phase friction pressure drop. It was shown that the two-phase friction multipliers for vertical upflow and reduced gravity conditions can be successfully predicted by the appropriate normal gravity models. Limited critical heat flux data showed that the measured CHF under reduced gravities are of the same order of magnitude as the test results with vertical upflow configuration. A simplified correlation was only successful in predicting the measured CHF for low flow rates. Instability tests with vertical upflow showed that flow becomes unstable and critical heat flux occurs at smaller powers when a parallel flow path exists. However, downflow tests and a single reduced gravity instability experiment indicated that the system actually became more stable with a

  11. Two-phase heat transfer and pressure drop of LNG during saturated flow boiling in a horizontal tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-12-01

    Two-phase heat transfer and pressure drop of LNG (liquefied natural gas) have been measured in a horizontal smooth tube with an inner diameter of 8 mm. The experiments were conducted at inlet pressures from 0.3 to 0.7 MPa with a heat flux of 8-36 kW m-2, and mass flux of 49.2-201.8 kg m-2 s-1. The effect of vapor quality, inlet pressure, heat flux and mass flux on the heat transfer characteristic are discussed. The comparisons of the experimental data with the predicted value by existing correlations are analyzed. Zou et al. (2010) correlation shows the best accuracy with 24.1% RMS deviation among them. Moreover four frictional pressure drop methods are also chosen to compare with the experimental database.

  12. Study on heat transfer and pressure drop characteristics of internal heat exchangers in CO2 system under cooling condition

    NASA Astrophysics Data System (ADS)

    Kim, Dae Hoon; Lee, Jae-Heon; Choi, Jun Young; Kwon, Young Chul

    2009-12-01

    In order to study the heat transfer and pressure drop on four types of internal heat exchangers (IHXs) of a CO2 system, the experiment and numerical analysis were performed under a cooling condition. The configuration of the IHXs was a coaxial type and a micro-channel type. Two loops on the gas cooler part and the evaporator part were made, for experiment. And the section-by-section method and Hardy-Cross method were used for the numerical analysis. The capacity and pressure drop of the IHX are larger at the micro-channel type than at the coaxial type. When increasing the mass flow rate and the IHX length the capacity and pressure drop increase. The pressure drop of the evaporator loop is much larger than that of the gas cooler loop. The performance of the IHX was affected with operating condition of the gas-cooler and evaporator. The deviations between the experimental result and the numerical result are about ±20% for the micro-channel type and ±10% for the coaxial type. Thus, the new CO2 heat transfer correlation should be developed to precisely predict a CO2 heat transfer.

  13. Boiling Heat Transfer and Pressure Drop of a Refrigerant Flowing Vertically Upward in a Small Diameter Tube

    NASA Astrophysics Data System (ADS)

    Miyata, Kazushi; Mori, Hideo; Ohishi, Katsumi; Tanaka, Hirokazu

    In the present study, experiments were performed to examine characteristics of flow boiling heat transfer and pressure drop of a refrigerant R410A flowing vertically upward in a copper smooth tube with 1.0 mm inside diameter for the development of a high-performance heat exchanger using small diameter tubes for air conditioning systems. Local heat transfer coefficients were measured in a range of mass fluxes from 30 to 200 kg/(m2•s), heat fluxes from 1 to 16 kW/m2 and qualities from 0.1 to over 1 at evaporation temperature of 10°C, and pressure drops were also measured at mass fluxes of 100 and 200 kg/(m2•s) and qualities from 0.1 to 0.9. Three types of flow pattern were observed in the tube: A slug, a slug-annular and an annular flow. Based on the measurements, the characteristics of frictional pressure drop, heat transfer coefficient and dryout qualities were clarified. The measured pressure drop and heat transfer coefficient were compared with correlations.

  14. Comparative study of heat transfer and pressure drop during flow boiling and flow condensation in minichannels

    NASA Astrophysics Data System (ADS)

    Mikielewicz, Dariusz; Andrzejczyk, Rafał; Jakubowska, Blanka; Mikielewicz, Jarosław

    2014-09-01

    In the paper a method developed earlier by authors is applied to calculations of pressure drop and heat transfer coefficient for flow boiling and also flow condensation for some recent data collected from literature for such fluids as R404a, R600a, R290, R32,R134a, R1234yf and other. The modification of interface shear stresses between flow boiling and flow condensation in annular flow structure are considered through incorporation of the so called blowing parameter. The shear stress between vapor phase and liquid phase is generally a function of nonisothermal effects. The mechanism of modification of shear stresses at the vapor-liquid interface has been presented in detail. In case of annular flow it contributes to thickening and thinning of the liquid film, which corresponds to condensation and boiling respectively. There is also a different influence of heat flux on the modification of shear stress in the bubbly flow structure, where it affects bubble nucleation. In that case the effect of applied heat flux is considered. As a result a modified form of the two-phase flow multiplier is obtained, in which the nonadiabatic effect is clearly pronounced.

  15. Measurement of heat transfer and pressure drop in rectangular channels with turbulence promoters

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Park, J. S.; Ibrahim, M. Y.

    1986-01-01

    Periodic rib turbulators were used in advanced turbine cooling designs to enhance the internal heat transfer. The objective of the present project was to investigate the combined effects of the rib angle of attack and the channel aspect ratio on the local heat transfer and pressure drop in rectangular channels with two opposite ribbed walls for Reynolds number varied from 10,000 to 60,000. The channel aspect ratio (W/H) was varied from 1 to 2 to 4. The rib angle of attack (alpha) was varied from 90 to 60 to 45 to 30 degree. The highly detailed heat transfer coefficient distribution on both the smooth side and the ribbed side walls from the channel sharp entrance to the downstream region were measured. The results showed that, in the square channel, the heat transfer for the slant ribs (alpha = 30 -45 deg) was about 30% higher that of the transverse ribs (alpha = 90 deg) for a constant pumping power. However, in the rectangular channels (W/H = 2 and 4, ribs on W side), the heat transfer at alpha = 30 -45 deg was only about 5% higher than 90 deg. The average heat transfer and friction correlations were developed to account for rib spacing, rib angle, and channel aspect ratio over the range of roughness Reynolds number.

  16. Heat transfer and pressure drop in blade cooling channels with turbulence promoters

    NASA Technical Reports Server (NTRS)

    Han, J. C.; Park, J. S.; Lei, C. K.

    1984-01-01

    Repeated rib roughness elements have been used in advanced turbine cooling designs to enhance the internal heat transfer. Often the ribs are perpendicular to the main flow direction so that they have an angle-of-attack of 90 deg. The objective of the project was to investigate the effect of rib angle-of-attack on the pressure drop and the average heat transfer coefficients in a square duct with two opposite rib-roughned walls for Reynolds number varied from 8000 to 80,000. The rib height-to-equivalent diameter ratio (e/D) was kept at a constant value of 0.063, the rib pitch-to-height ratio (P/e) was varied from 10 to 20, and the rib angle-of-attack (alpha) was varied from 90 deg to 60 deg to 45 deg to 30 deg respectively. Two types of entrance conditions were examined, namely, long duct and sudden contraction. The heat transfer coefficient distribution on the smooth side wall and the rough side wall at the entrance and the fully developed regions were measured. Thermal performance comparison indicated that the pumping power requirement for the rib with an oblique angle to the flow (alpha = 45 deg to 30 deg) was about 20 to 50 percent lower than the rib with a 90 deg angle to the flow for a given heat transfer duty.

  17. Impact of instantaneous controlled pressure drop on microstructural modification of green tea and its infusion quality.

    PubMed

    Wang, Yuefei; Xu, Ping; Feng, Liyun; Yang, Xianqiang; Qian, Lisheng

    2014-01-01

    Instantaneous controlled pressure drop (DIC) was applied to obtain a suitable cell disruption extent as a technology in green tea processing. Microstructural observations showed that DIC increased cell disruption in an even manner as reflected from loosened palisade, distorted cells, widened space between cells, disrupted and rearranged cellular membrane in tea leaves. Color difference determination supported that DIC could facilitate the release and transport of cell contents. DIC sample showed a rise in redness, over 2.5 times greater than the control after spreading naturally for 24 h. Chemical determination revealed a better infusion behavior of tea polyphenols and amino acids in green tea manufactured by DIC method both at high and low temperature. The increase in tea polyphenols content in liquor for the first brew from twisted and needle tea was about 35% and that from flat tea was about 15% in DIC method over the traditional processing. These results suggest that DIC process can be applied in green tea processing for both a traditional product and a new kind of tea capable of making with cold water. PMID:24426047

  18. Antimicrobial nanoparticle-coated electrostatic air filter with high filtration efficiency and low pressure drop.

    PubMed

    Sim, Kyoung Mi; Park, Hyun-Seol; Bae, Gwi-Nam; Jung, Jae Hee

    2015-11-15

    In this study, we demonstrated an antimicrobial nanoparticle-coated electrostatic (ES) air filter. Antimicrobial natural-product Sophora flavescens nanoparticles were produced using an aerosol process, and were continuously deposited onto the surface of air filter media. For the electrostatic activation of the filter medium, a corona discharge electrification system was used before and after antimicrobial treatment of the filter. In the antimicrobial treatment process, the deposition efficiency of S. flavescens nanoparticles on the ES filter was ~12% higher than that on the pristine (Non-ES) filter. In the evaluation of filtration performance using test particles (a nanosized KCl aerosol and submicron-sized Staphylococcus epidermidis bioaerosol), the ES filter showed better filtration efficiency than the Non-ES filter. However, antimicrobial treatment with S. flavescens nanoparticles affected the filtration efficiency of the filter differently depending on the size of the test particles. While the filtration efficiency of the KCl nanoparticles was reduced on the ES filter after the antimicrobial treatment, the filtration efficiency was improved after the recharging process. In summary, we prepared an antimicrobial ES air filter with >99% antimicrobial activity, ~92.5% filtration efficiency (for a 300-nm KCl aerosol), and a ~0.8 mmAq pressure drop (at 13 cm/s). This study provides valuable information for the development of a hybrid air purification system that can serve various functions and be used in an indoor environment. PMID:26172593

  19. Summary report for ITER Task-T19: MHD pressure drop and heat transfer study for liquid metal systems

    NASA Astrophysics Data System (ADS)

    Reed, Claude B.; Hua, Thanh Q.; Natesan, Ken; Kirillov, Igor R.; Vitkovski, Ivan V.; Anisimov, Aleksandr M.

    1995-03-01

    A key feasibility issue for the ITER Vanadium/Lithium breeding blanket is the question of insulator coatings. Design calculations show that an electrically insulating layer is necessary to maintain an acceptably low MHD pressure drop. To begin experimental investigations of the MHD performance of candidate insulator materials and the technology for putting them in place, a new test section was prepared. Aluminum oxide was chosen as the first candidate insulating material because it may be used in combination with NaK in the ITER vacuum vessel and/or the divertor. Details on the methods used to produce the aluminum oxide layer as well as the microstructures of the coating and the aluminide sublayer are presented and discussed. The overall MHD pressure drop, local MHD pressure gradient, local transverse MHD pressure difference, and surface voltage distributions in both the circumferential and the axial directions are reported and discussed. The positive results obtained here for high-temperature NaK have two beneficial implications for ITER. First, since NaK may be used in the vacuum vessel and/or the divertor, these results support the design approach of using electrically insulating coatings to substantially reduce MHD pressure drop. Secondly, while Al2O3/SS is not the same coating/base material combination which would be used in the advanced blanket, this work nonetheless shows that it is possible to produce a viable insulating coating which is stable in contact with a high temperature alkali metal coolant.

  20. The effect of passive mixing on pressure drop and oxygen mass fraction using opposing channel flow field design in a Proton Exchange Membrane Fuel Cell

    NASA Astrophysics Data System (ADS)

    Singh, Anant Bir

    This study investigates a flow field with opposing channel design. Previous studies on flow field designs have been focused on improving fuel utilization which often leads to increased pressure drop. This increased pressure drop is typical because standard designs employ either a single flow channel to clear blockages or dead end condition to force the flow through the gas diffusion layer. The disadvantage with these designs is the increased resistance to the flow which requires higher pressure, which becomes a parasitic loss that lowers the system efficiency. For this study the focus was to reduce the pressure drop by providing a less resistive path to the flow. To achieve a less resistive path, the inlet channel was split into two opposing channels. These channels are then recombined only to be split again for the next leg. Therefore, the split channel design should reduce the pressure drop which reduces the parasitic load and ultimately contributes to higher system efficiency. In addition the recombining of the streams at each leg should induce mixing. Having opposing channels should also increase cross flow under the lands to reduce mass transfer loses. The cathode side of the fuel cell is especially sensitive to the mass transport losses since air (oxygen mixed with nitrogen) is used for supplying oxygen unlike the anode side which uses pure hydrogen. To test the hypothesis of having benefits from an opposing channel design, both an experimental and analytical approach was taken. For the experiment, a serpentine flow field and opposing channel flow field plates were compared over several flow rates with compressed air. To test the hypothesis of increased mass transfer, the two flow fields were modeled using a CFD software package, COMSOL. It was found that the opposing channel configuration for high flow rate with multiple entry and exit conditions exhibited significant improvement over the single serpentine channel. Pressure drop was ⅓ less than the

  1. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

    NASA Astrophysics Data System (ADS)

    Elazhary, Amr Mohamed; Soliman, Hassan M.

    2012-10-01

    An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

  2. An empirical investigation on thermal characteristics and pressure drop of Ag-oil nanofluid in concentric annular tube

    NASA Astrophysics Data System (ADS)

    Abbasian Arani, A. A.; Aberoumand, H.; Aberoumand, S.; Jafari Moghaddam, A.; Dastanian, M.

    2016-08-01

    In this work an experimental study on Silver-oil nanofluid was carried out in order to present the laminar convective heat transfer coefficient and friction factor in a concentric annulus with constant heat flux boundary condition. Silver-oil nanofluid prepared by Electrical Explosion of Wire technique with no nanoparticles agglomeration during nanofluid preparation process and experiments. The average sizes of particles were 20 nm. Nanofluids with various particle Volume fractions of 0.011, 0.044 and 0.171 vol% were employed. The nanofluid flowing between the tubes is heated by an electrical heating coil wrapped around it. The effects of different parameters such as flow Reynolds number, tube diameter ratio and nanofluid particle concentration on heat transfer coefficient are studied. Results show that, heat transfer coefficient increased by using nanofluid instead of pure oil. Maximum enhancement of heat transfer coefficient occurs in 0.171 vol%. In addition the results showed that, there are slight increases in pressure drop of nanofluid by increasing the nanoparticle concentration of nanofluid in compared to pure oil.

  3. A study of pressure drop in a Capillary tube-viscometer for a two-phase flow

    SciTech Connect

    Ohene, F.; Livingston, C.; Matthews, C.; Rhone, Y.

    1995-09-01

    The analysis of pipeline transportation of highly concentrated suspensions such as coal-water slurries, can exhibit several flow characteristics depending on the concentration and the physical parameters of the dispersed phase. Experiments were conducted for coal-water slurries flows in a series of horizontal capillary tubes of diameters 0.8, 1.5 and 3.0 mm and 100 mm in length, in order to investigate the effect of concentration, pressure drop, and the transitional Reynolds number from laminar to turbulent flow in a homogeneous slurry. The solid concentration was varied from 15% to 63% in 0.1% xanthum gum solution. Pressure drop and the volume flow measurement were made using HVA-6 Capillary viscometer. The Reynolds numbers obtained were found to be dependent on the slurry concentration and the viscosity of the slurry mixture, but independent of the capillary diameter.

  4. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  5. Smooth- and enhanced-tube heat transfer and pressure drop : Part II. The role of transition to turbulent flow.

    SciTech Connect

    Obot, N. T.; Das, L.; Rabas, T. J.

    2000-11-14

    The objectives of this presentation are two-fold: first, to demonstrate the connection between the attainable coefficients and transition to turbulent flow by using the transition-based corresponding states method to generalize results obtained with smooth tubes and enhanced tubes, and second, to provide guidelines on the calculation of heat transfer coefficients from pressure-drop data and vice versa by using the transition concept or the functional law of corresponding states.

  6. On axial temperature gradients due to large pressure drops in dense fluid chromatography.

    PubMed

    Colgate, Sam O; Berger, Terry A

    2015-03-13

    The effect of energy degradation (Degradation is the creation of net entropy resulting from irreversibility.) accompanying pressure drops across chromatographic columns is examined with regard to explaining axial temperature gradients in both high performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The observed effects of warming and cooling can be explained equally well in the language of thermodynamics or fluid dynamics. The necessary equivalence of these treatments is reviewed here to show the legitimacy of using whichever one supports the simpler determination of features of interest. The determination of temperature profiles in columns by direct application of the laws of thermodynamics is somewhat simpler than applying them indirectly by solving the Navier-Stokes (NS) equations. Both disciplines show that the preferred strategy for minimizing the reduction in peak quality caused by temperature gradients is to operate columns as nearly adiabatically as possible (i.e. as Joule-Thomson expansions). This useful fact, however, is not widely familiar or appreciated in the chromatography community due to some misunderstanding of the meaning of certain terms and expressions used in these disciplines. In fluid dynamics, the terms "resistive heating" or "frictional heating" have been widely used as synonyms for the dissipation function, Φ, in the NS energy equation. These terms have been widely used by chromatographers as well, but often misinterpreted as due to friction between the mobile phase and the column packing, when in fact Φ describes the increase in entropy of the system (dissipation, ∫TdSuniv>0) due to the irreversible decompression of the mobile phase. Two distinctly different contributions to the irreversibility are identified; (1) ΔSext, viscous dissipation of work done by the external surroundings driving the flow (the pump) contributing to its warming, and (2) ΔSint, entropy change accompanying decompression of

  7. Pressure drop of two-phase plug flow in round mini-channels: Influence of surface wettability

    SciTech Connect

    Lee, Chi Young; Lee, Sang Yong

    2008-09-15

    In the present experimental study, the pressure drop of two-phase plug flows in round mini-channels was investigated for three different tube materials, i.e., glass, polyurethane and Teflon, respectively, with their inner diameters ranging from 1.62 to 2.16 mm. Air and water were used as the test fluids. In the wet-plug flow regime (wet wall condition at the gas portions), the pressure drop was reasonably predicted by the homogeneous flow model or by the correlations of Mishima and Hibiki [K. Mishima, T. Hibiki, Some characteristics of air-water two-phase flow in small diameter vertical tubes, Int. J. Multiphase Flow 22 (1996) 703-712] and Chisholm [D. Chisholm, A theoretical basis for the Lockhart-Martinelli correlation for two-phase flow, Int. J. Heat Mass Transfer 10 (1967) 1767-1778]. On the other hand, in the dry-plug flow regime (dry wall condition at the gas portions), the role of the moving contact lines turned out to be significant. To take into account the effect of the moving contact lines, a modified Lockhart-Martinelli type correlation was proposed, which fitted the measured pressure-drop data within the mean deviation of 6%. (author)

  8. Pressure drop of two-phase dry-plug flow in round mini-channels: Effect of moving contact line

    SciTech Connect

    Lee, Chi Young; Lee, Sang Yong

    2010-01-15

    In the present experimental study, the pressure drop of the two-phase dry-plug flow (dry wall condition at the gas portions) in round mini-channels was investigated. The air-water mixtures were flowed through the round mini-channels made of polyurethane and Teflon, respectively, with their inner diameters ranging from 1.62 to 2.16 mm. In the dry-plug flow regime, the pressure drop measured became larger either by increasing the liquid superficial velocity or by decreasing the gas superficial velocity due to the increase of the number of the moving contact lines in the test section. In such a case, the role of the moving contact lines turned out to be significant. Therefore, a pressure drop model of dry-plug flow was proposed through modification of the dynamic contact angle analysis taking account of the energy dissipation by the moving contact lines, which represents the experimental data within the mean deviation of 4%. (author)

  9. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  10. Quadratic formula for determining the drop size in pressure-atomized sprays with and without swirl

    NASA Astrophysics Data System (ADS)

    Lee, T.-W.; An, Keju

    2016-06-01

    We use a theoretical framework based on the integral form of the conservation equations, along with a heuristic model of the viscous dissipation, to find a closed-form solution to the liquid atomization problem. The energy balance for the spray renders to a quadratic formula for the drop size as a function, primarily of the liquid velocity. The Sauter mean diameter found using the quadratic formula shows good agreements and physical trends, when compared with experimental observations. This approach is shown to be applicable toward specifying initial drop size in computational fluid dynamics of spray flows.

  11. Shape oscillations of acoustically levitated drops in water: Early research with Bob Apfel on modulated radiation pressure

    NASA Astrophysics Data System (ADS)

    Marston, Philip L.

    2001-05-01

    In 1976, research in collaboration with Bob Apfel demonstrated that low-frequency shape oscillations of hydrocarbon drops levitated in water could be driven using modulated radiation pressure. While that response to modulated ultrasound was subsequently extended to a range of systems, the emphasis here is to recall the initial stages of development in Bob Apfel's laboratory leading to some publications [P. L. Marston and R. E. Apfel, J. Colloid Interface Sci. 68, 280-286 (1979); J. Acoust. Soc. Am. 67, 27-37 (1980)]. The levitation technology used at that time was such that it was helpful to develop a sensitive method for detecting weak oscillations using the interference pattern in laser light scattered by levitated drops. The initial experiments to verify this scattering method used shape oscillations induced by modulated electric fields within the acoustic levitator. Light scattering was subsequently used to detect shape oscillations induced by amplitude modulating a carrier having a high frequency (around 680 kHz) at a resonance of the transducer. Methods were also developed for quantitative measurements of the drop's response and with improved acoustic coupling drop fission was observed. The connection with research currently supported by NASA will also be noted.

  12. Impact of biofilm accumulation on transmembrane and feed channel pressure drop: effects of crossflow velocity, feed spacer and biodegradable nutrient.

    PubMed

    Dreszer, C; Flemming, H-C; Zwijnenburg, A; Kruithof, J C; Vrouwenvelder, J S

    2014-03-01

    Biofilm formation causes performance loss in spiral-wound membrane systems. In this study a microfiltration membrane was used in experiments to simulate fouling in spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules without the influence of concentration polarization. The resistance of a microfiltration membrane is much lower than the intrinsic biofilm resistance, enabling the detection of biofilm accumulation in an early stage. The impact of biofilm accumulation on the transmembrane (biofilm) resistance and feed channel pressure drop as a function of the crossflow velocity (0.05 and 0.20 m s(-1)) and feed spacer presence was studied in transparent membrane biofouling monitors operated at a permeate flux of 20 L m(-2) h(-1). As biodegradable nutrient, acetate was dosed to the feed water (1.0 and 0.25 mg L(-1) carbon) to enhance biofilm accumulation in the monitors. The studies showed that biofilm formation caused an increased transmembrane resistance and feed channel pressure drop. The effect was strongest at the highest crossflow velocity (0.2 m s(-1)) and in the presence of a feed spacer. Simulating conditions as currently applied in nanofiltration and reverse osmosis installations (crossflow velocity 0.2 m s(-1) and standard feed spacer) showed that the impact of biofilm formation on performance, in terms of transmembrane and feed channel pressure drop, was strong. This emphasized the importance of hydrodynamics and feed spacer design. Biomass accumulation was related to the nutrient load (nutrient concentration and linear flow velocity). Reducing the nutrient concentration of the feed water enabled the application of higher crossflow velocities. Pretreatment to remove biodegradable nutrient and removal of biomass from the membrane elements played an important part to prevent or restrict biofouling. PMID:24374131

  13. Heat transfer, pressure drop, and mass flow rate in pin fin channels with long and short trailing edge ejection holes

    NASA Astrophysics Data System (ADS)

    Lau, S. C.; Han, J. C.; Batten, T.

    1988-06-01

    The turbulent heat transfer and friction characteristics in the pin fin channels with small trailing edge ejection holes found in internally-cooled turbine airfoils have been experimentally investigated. It is found that the overall heat transfer increases when the length of the trailing edge ejection holes is increased and when the trailing edge ejection holes are configured such that much of the cooling air is forced to flow further downstream in the radial flow direction prior to exiting. The increase in the overall heat transfer is shown to be accompanied by an increase in the overall pressure drop.

  14. Constant-Pressure Combustion Charts Including Effects of Diluent Addition

    NASA Technical Reports Server (NTRS)

    Turner, L Richard; Bogart, Donald

    1949-01-01

    Charts are presented for the calculation of (a) the final temperatures and the temperature changes involved in constant-pressure combustion processes of air and in products of combustion of air and hydrocarbon fuels, and (b) the quantity of hydrocarbon fuels required in order to attain a specified combustion temperature when water, alcohol, water-alcohol mixtures, liquid ammonia, liquid carbon dioxide, liquid nitrogen, liquid oxygen, or their mixtures are added to air as diluents or refrigerants. The ideal combustion process and combustion with incomplete heat release from the primary fuel and from combustible diluents are considered. The effect of preheating the mixture of air and diluents and the effect of an initial water-vapor content in the combustion air on the required fuel quantity are also included. The charts are applicable only to processes in which the final mixture is leaner than stoichiometric and at temperatures where dissociation is unimportant. A chart is also included to permit the calculation of the stoichiometric ratio of hydrocarbon fuel to air with diluent addition. The use of the charts is illustrated by numerical examples.

  15. PRESSURE DROP OF FILTERING FACEPIECE RESPIRATORS: HOW LOW SHOULD WE GO?

    PubMed Central

    Kim, Jung-Hyun; Roberge, Raymond J.; Powell, Jeffrey B.; Shaffer, Ronald E.; Ylitalo, Caroline M.; Sebastian, John M.

    2015-01-01

    Objectives This study was undertaken to determine the mean peak filter resistance to airflow (Rfilter) encountered by subjects while wearing prototype filtering facepiece respirators (PRs) with low Rfilter during nasal and oral breathing at sedentary and low-moderate work rates. Material and Methods In-line pressure transducer measurements of mean Rfilter across PRs with nominal Rfilter of 29.4 Pa, 58.8 Pa and 88.2 Pa (measured at 85 l/min constant airflow) were obtained during nasal and oral breathing at sedentary and low-moderate work rates for 10 subjects. Results The mean Rfilter for the 29.4 PR was significantly lower than the other 2 PRs (p < 0.000), but there were no significant differences in mean Rfilter between the PRs with 58.8 and 88.2 Pa filter resistance (p > 0.05). The mean Rfilter was greater for oral versus nasal breathing and for exercise compared to sedentary activity (p < 0.001). Conclusions Mean oral and nasal Rfilter for all 3 PRs was at, or below, the minimal threshold level for detection of inspiratory resistance (the 58.8–74.5 Pa/1×s−1), which may account for the previously-reported lack of significant subjective or physiological differences when wearing PRs with these low Rfilter. Lowering filtering facepiece respirator Rfilter below 88.2 Pa (measured at 85 l/min constant airflow) may not result in additional subjective or physiological benefit to the wearer. PMID:26159949

  16. Tribological performance of ashless antiwear additives under extreme pressure conditions

    NASA Astrophysics Data System (ADS)

    Kim, Bohoon

    Zinc diakyl dithiophosphate (ZDDP) has been used in engine oil for several decades as an antiwear additive. However, ZDDP is the primary source of P, S and Zn in the exhaust, which results in frequent maintenance or replacement of exhaust gas treatment systems. The use of ashless additives is more desirable because of recent environmental regulations. The main goal of this research was to develop a fundamental understanding of how ashless compounds protect the tribological surface in comparison to ZDDP. X-ray absorption near edge structure spectroscopy (XANES) has been performed on tribo and thermal films in order to investigate the chemical properties of films generated from ashless antiwear additives like chemical structure as well as chemical composition. In order to achieve this objective, three approaches were used. First, the relationships between ashless thiophosphates and wear properties under extreme pressure were examined. Ashless antiwear additives properly form their tribofilms on the sliding steel surface, reacting with iron (Fe) which is originated from the substrate. The tribofilms consist of iron phosphates, iron sulfides, and iron sulfates that have lower reduced modulus and hardness compared to tribofilms from ZDDP. However, they are still sufficiently stiff to prevent asperity contact and provide antiwear behavior. In addition, the thickness of protective tribofilms formed with ashless thiophosphates was found to be thicker than the ones formed when ZDDP was used under identical tribological conditions. Secondly, in order to understand the mechanism of tribofilm generation of metal free additives, a fundamental understanding of thermal decomposition of ashless antiwear chemistries and their influence on thermal film formation was derived. The decomposed P- and S- containing products of ZDDP reacted with the metal surface and their own metal cations forming thermal films. In case of metal free dithiophosphates, sulfur species initially formed on

  17. In vitro comparison of Günther Tulip and Celect filters: testing filtering efficiency and pressure drop.

    PubMed

    Nicolas, M; Malvé, M; Peña, E; Martínez, M A; Leask, R

    2015-02-01

    In this study, the trapping ability of the Günther Tulip and Celect inferior vena cava filters was evaluated. Thrombus capture rates of the filters were tested in vitro in horizontal position with thrombus diameters of 3 and 6mm and tube diameter of 19mm. The filters were tested in centered and tilted positions. Sets of 30 clots were injected into the model and the same process was repeated 20 times for each different condition simulated. Pressure drop experienced along the system was also measured and the percentage of clots captured was recorded. The Günther Tulip filter showed superiority in all cases, trapping almost 100% of 6mm clots both in an eccentric and tilted position and trapping 81.7% of the 3mm clots in a centered position and 69.3% in a maximum tilted position. The efficiency of all filters tested decreased as the size of the embolus decreased and as the filter was tilted. The injection of 6 clots raised the pressure drop to 4.1mmHg, which is a reasonable value that does not cause the obstruction of blood flow through the system. PMID:25553669

  18. Bed mixing and leachate recycling strategies to overcome pressure drop buildup in the biofiltration of hydrogen sulfide.

    PubMed

    Roshani, Babak; Torkian, Ayoob; Aslani, Hasan; Dehghanzadeh, Reza

    2012-04-01

    The effects of leachate recycling and bed mixing on the removal rate of H(2)S from waste gas stream were investigated. The experimental setup consisted of an epoxy-coated three-section biofilter with an ID of 8 cm and effective bed height of 120 cm. Bed material consisted of municipal solid waste compost and PVC bits with an overall porosity of 54% and dry bulk density of 0.456 g cm(-3). Leachate recycling had a positive effect of increasing elimination capacity (EC) up to 21 g S m(-3) bed h(-1) at recycling rates of 75 ml d(-1), but in the bed mixing period EC declined to 8 g S m(-3) bed h(-1). Pressure drop had a range of zero to 18 mm H(2)O m(-1) in the course of leachate recycling. Accumulation of sulfur reduced removal efficiency and increased pressure drop up to 110 mm H(2)O m(-1) filter during the bed mixing stage. PMID:22300638

  19. A simple expression for pressure drops of water and other low molecular liquids in the flow through micro-orifices

    NASA Astrophysics Data System (ADS)

    Hasegawa, Tomiichi; Ushida, Akiomi; Narumi, Takatsune

    2015-12-01

    Flows are generally divided into two types: shear flows and shear-free elongational (extensional) flows. Both are necessary for a thorough understanding of the flow properties of a fluid. Shear flows are easy to achieve in practice, for example, through Poiseuille or Couette flows. Shear-free elongational flows are experimentally hard to achieve, resulting in an incomplete understanding of the flow properties of fluids in micro-devices. Nevertheless, flows through micro-orifices are useful for probing the properties of elongational flows at high elongational rates; although these flows exhibit shear and elongation, the elongation is dominant and the shear is negligible in the central region of the flows. We previously reported an anomalous reduction in pressure drops in the flows of water, a 50/50 mixture of glycerol and water, and silicone oils through micro-orifices. In the present paper, we rearrange the data presented in the previous paper and reveal a simple relationship where the pressure drop is proportional to the velocity through the micro-orifices, independent of the orifice diameter and the viscosity of the liquids tested. We explain our observations by introducing a "fluid element" model, in which fluid elements are formed on entering the orifice. The model is based on the idea that low molecular liquids, including water, generate strong elongational stress, similar to a polymer solution, in the flow through micro-orifices.

  20. Evaluation of static pressure drops and PM10 and TSP emissions for modified 1D-3D cyclones

    SciTech Connect

    Holt, G.A.; Baker, R.V.; Hughs, S.E.

    1999-12-01

    Five modifications of a standard 1D3D cyclone were tested and compared against the standard 1D3D design in the areas of particulate emissions and static pressure drop across the cyclone. The modifications to the 1D3D design included a 2D2D inlet, a 2D2D air outlet, a D/3 trash exit, an expansion chamber with a D/3 trash exit, and a tapered air outlet duct. The 1D3D modifications that exhibited a significant improvement in reducing both PM10 and total suspended particulate (TSP) emissions were the designs with the 2D2D inlet and air exhaust combined with either the conical D/3 tail cone or the expansion chamber. In reference to the standard 1D3D cyclone, the average reduction in PM10 emissions was 24 to 29% with a 29 to 35% reduction observed in TSP emissions. The modifications with the tapered air outlets did not show any significant improvements in controlling PM10 emissions. However, the modification with the tapered air outlet/expansion chamber combination exhibited statistical significance in reducing TSP emissions by 18% compared to the 1D3D cyclone. All modifications tested exhibited lower static pressure drops than the standard 1D3D.

  1. Heat transfer and pressure drop of supercritical carbon dioxide flowing in several printed circuit heat exchanger channel patterns

    SciTech Connect

    Carlson, M.; Kruizenga, A.; Anderson, M.; Corradini, M.

    2012-07-01

    Closed-loop Brayton cycles using supercritical carbon dioxide (SCO{sub 2}) show potential for use in high-temperature power generation applications including High Temperature Gas Reactors (HTGR) and Sodium-Cooled Fast Reactors (SFR). Compared to Rankine cycles SCO{sub 2} Brayton cycles offer similar or improved efficiency and the potential for decreased capital costs due to a reduction in equipment size and complexity. Compact printed-circuit heat exchangers (PCHE) are being considered as part of several SCO{sub 2} Brayton designs to further reduce equipment size with increased energy density. Several designs plan to use a gas cooler operating near the pseudo-critical point of carbon dioxide to benefit from large variations in thermophysical properties, but further work is needed to validate correlations for heat transfer and pressure-drop characteristics of SCO{sub 2} flows in candidate PCHE channel designs for a variety of operating conditions. This paper presents work on experimental measurements of the heat transfer and pressure drop behavior of miniature channels using carbon dioxide at supercritical pressure. Results from several plate geometries tested in horizontal cooling-mode flow are presented, including a straight semi-circular channel, zigzag channel with a bend angle of 80 degrees, and a channel with a staggered array of extruded airfoil pillars modeled after a NACA 0020 airfoil with an 8.1 mm chord length facing into the flow. Heat transfer coefficients and bulk temperatures are calculated from measured local wall temperatures and local heat fluxes. The experimental results are compared to several methods for estimating the friction factor and Nusselt number of cooling-mode flows at supercritical pressures in millimeter-scale channels. (authors)

  2. ADDITIONAL STRESS AND FRACTURE MECHANICS ANALYSES OF PRESSURIZED WATER REACTOR PRESSURE VESSEL NOZZLES

    SciTech Connect

    Walter, Matthew; Yin, Shengjun; Stevens, Gary; Sommerville, Daniel; Palm, Nathan; Heinecke, Carol

    2012-01-01

    In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperature (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives: To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle). To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated. To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles. These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, Fracture Toughness Requirements, and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP

  3. Condensation heat transfer and pressure drop of R-134a saturated vapour inside a brazed compact plate fin heat exchanger with serrated fin

    NASA Astrophysics Data System (ADS)

    Ramana Murthy, K. V.; Ranganayakulu, C.; Ashok Babu, T. P.

    2016-05-01

    This paper presents the experimental heat transfer coefficient and pressure drop measured during R-134a saturated vapour condensation inside a small brazed compact plate fin heat exchanger with serrated fin surface. The effects of saturation temperature (pressure), refrigerant mass flux, refrigerant heat flux, effect of fin surface characteristics and fluid properties are investigated. The average condensation heat transfer coefficients and frictional pressure drops were determined experimentally for refrigerant R-134a at five different saturated temperatures (34, 38, 40, 42 and 44 °C). A transition point between gravity controlled and forced convection condensation has been found for a refrigerant mass flux around 22 kg/m2s. In the forced convection condensation region, the heat transfer coefficients show a three times increase and 1.5 times increase in frictional pressure drop for a doubling of the refrigerant mass flux. The heat transfer coefficients show weak sensitivity to saturation temperature (Pressure) and great sensitivity to refrigerant mass flux and fluid properties. The frictional pressure drop shows a linear dependence on the kinetic energy per unit volume of the refrigerant flow. Correlations are provided for the measured heat transfer coefficients and frictional pressure drops.

  4. Pressure drop testing of corrugated stainless steel pliable gas tubing (PLT)

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bharadwaj

    An experimental program was initiated to determine the Darcy friction factor in straight corrugated stainless steel pliable gas tubing (PLT). Pressure loss tests were conducted on PLT per I.S. EN 15266:2007. A power law least-squares curve fit was used to relate pressure loss per unit length as a function of volume flow rate. The calculated coefficient of determination values for the straight PLT exceeded 0.90 indicating suitable correlation. Darcy friction factors were calculated from test data for each case and plotted on a Moody diagram as a function of Reynolds number based on the minimum PLT cross section. For Reynolds numbers less than 2300 the pressure loss data for PLT yielded an inverse relationship between the Darcy friction factor and the Reynolds number, with a proportionality coefficient of 49. The measurement uncertainty estimates for straight sections was performed with a 95% confidence level. Straight PLT flow rates for air and representative fuel gases that would yield a pressure loss Deltap = 1 mbar were calculated as a function of PLT length and diameter. Fitting pressure loss tests were performed for elbows, tees, and bullhead tees. The loss coefficients were evaluated and tabulated. The calculated coefficient of determination values for the fittings was found to be low. The measurement uncertainty was calculated using the root sum square error method and was found to be very high because of the low flow rates considered in this experiment.

  5. Fluctuation emergence of bubbles under a rapid drop of pressure in a liquid

    NASA Astrophysics Data System (ADS)

    Pavlov, P. A.; Vinogradov, V. E.

    2015-07-01

    Explosive cavitation at the front of a negative-pressure pulse has been studied. Conditions for the emergence of bubbles by the mechanism of homogeneous fluctuation nucleation were identified. Those conditions feature a high rate of the phase transformation, with the vapor formation process being concentrated in time at the instant of attainment of a certain pressure. Under such conditions, the liquid cavitation strength is maximal, and its value can be predicted by the homogeneous nucleation theory. For implementing the regime with high nucleation frequency, a method based on passing a negative-pressure pulse across a region with locally heated liquid was employed. The cavitation kinetics was examined by monitoring the perturbation of the heat flow from a miniature heater. The experimental data were generalized using the theory of explosive vapor formation in shock boiling mode. A method for calculating the cavitation in the regime of the fluctuation emergence of bubbles was approbated.

  6. Earthquake dynamics. Mapping pressurized volcanic fluids from induced crustal seismic velocity drops.

    PubMed

    Brenguier, F; Campillo, M; Takeda, T; Aoki, Y; Shapiro, N M; Briand, X; Emoto, K; Miyake, H

    2014-07-01

    Volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth. Here, we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations. We used records of seismic noise from the Japanese Hi-net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude (M(w)) 9.0 Tohoku-Oki earthquake. We interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves. We suggest, therefore, that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems. PMID:24994652

  7. Pressure Drop and Heat Transfer Characteristics of The Fluid Flow through an Array of Interrupted, Parallel-Plate Heat Transfer Surfaces

    NASA Astrophysics Data System (ADS)

    Mochizuki, Sadanari; Yagi, Yoshinao

    A scale-up modeling technique was used to examine the effect of the geometrical properties of interrupted surfaces on the heat transfer and pressure drop performance of compact heat exchangers having off-set-strip and slotted fins. The test cores, each consisting of a number of machined copper finns, were tested in a subsonic wind tunnel. The heat transfer and the pressure drop for each test core was measured for various fin lengths (in flow direction) and slot distances. Flow visualization and local turbulence intensity and pressure measurements within each test core were also performed to gain insight into the mechanisms of heat transfer augmentation in compact heat exchangers with interrupted surfaces. The effect of the geometrical properties of the fins as well as the Reynolds number on the heat transfer rate and the pressure drop were determined and those results were interpreted in terms of observed flow structure. Basic heat transfer and pressure drop data are presented in terms of Colburn j-factors and Fanning friction factors plotted versus Reynolds number. An empirical correlation for heat transfer and pressure drop characteristics for off-set-strip fins are presented.

  8. Pressure Drop Across Woven Screens Under Uniform and Nonuniform Flow Conditions. [flow characteristics of water through Dutch twill and square weave fabrics

    NASA Technical Reports Server (NTRS)

    Ludewig, M.; Omori, S.; Rao, G. L.

    1974-01-01

    Tests were conducted to determine the experimental pressure drop and velocity data for water flowing through woven screens. The types of materials used are dutch twill and square weave fabrics. Pressure drop measures were made at four locations in a rectangular channel. The data are presented as change in pressure compared with the average entry velocity and the numerical relationship is determined by dividing the volumetric flow rate by the screen area open to flow. The equations of continuity and momentum are presented. A computer program listing an extension of a theoretical model and data from that computer program are included.

  9. Numerical simulation of blood flow and pressure drop in the pulmonary arterial and venous circulation.

    PubMed

    Qureshi, M Umar; Vaughan, Gareth D A; Sainsbury, Christopher; Johnson, Martin; Peskin, Charles S; Olufsen, Mette S; Hill, N A

    2014-10-01

    A novel multiscale mathematical and computational model of the pulmonary circulation is presented and used to analyse both arterial and venous pressure and flow. This work is a major advance over previous studies by Olufsen et al. (Ann Biomed Eng 28:1281-1299, 2012) which only considered the arterial circulation. For the first three generations of vessels within the pulmonary circulation, geometry is specified from patient-specific measurements obtained using magnetic resonance imaging (MRI). Blood flow and pressure in the larger arteries and veins are predicted using a nonlinear, cross-sectional-area-averaged system of equations for a Newtonian fluid in an elastic tube. Inflow into the main pulmonary artery is obtained from MRI measurements, while pressure entering the left atrium from the main pulmonary vein is kept constant at the normal mean value of 2 mmHg. Each terminal vessel in the network of 'large' arteries is connected to its corresponding terminal vein via a network of vessels representing the vascular bed of smaller arteries and veins. We develop and implement an algorithm to calculate the admittance of each vascular bed, using bifurcating structured trees and recursion. The structured-tree models take into account the geometry and material properties of the 'smaller' arteries and veins of radii ≥ 50 μm. We study the effects on flow and pressure associated with three classes of pulmonary hypertension expressed via stiffening of larger and smaller vessels, and vascular rarefaction. The results of simulating these pathological conditions are in agreement with clinical observations, showing that the model has potential for assisting with diagnosis and treatment for circulatory diseases within the lung. PMID:24610385

  10. Short term Heart Rate Variability to predict blood pressure drops due to standing: a pilot study

    PubMed Central

    2015-01-01

    Background Standing from a bed or chair may cause a significant lowering of blood pressure (ΔBP), which may have severe consequences such as, for example, falls in older subjects. The goal of this study was to develop a mathematical model to predict the ΔBP due to standing in healthy subjects, based on their Heart Rate Variability, recorded in the 5 minutes before standing. Methods Heart Rate Variability was extracted from an electrocardiogram, recorded from 10 healthy subjects during the 5 minutes before standing. The blood pressure value was measured before and after rising. A mathematical model aiming to predict ΔBP based on Heart Rate Variability measurements was developed using a robust multi-linear regression and was validated with the leave-one-subject-out cross-validation technique. Results The model predicted correctly the ΔBP in 80% of experiments, with an error below the measurement error of sphygmomanometer digital devices (±4.5 mmHg), a false negative rate of 7.5% and a false positive rate of 10%. The magnitude of the ΔBP was associated with a depressed and less chaotic Heart Rate Variability pattern. Conclusions The present study showes that blood pressure lowering due to standing can be predicted by monitoring the Heart Rate Variability in the 5 minutes before standing. PMID:26391336

  11. Flow rate/pressure drop data gathered from testing a sample of the Space Shuttle Strain Isolation Pad (SIP): Effects of ambient pressure combined with tension and compression conditions

    NASA Technical Reports Server (NTRS)

    Springfield, R. D.; Lawing, P. L.

    1983-01-01

    Tests were conducted on a sample of strain isolation pad (SIP) typical of that used in the shuttle orbiter thermal protection system to determine the characteristics of SIP internal flow. Data obtained were pressure drop as a function of flow rate for a range of ambient pressures representing various points along the Shuttle trajectory and for stretched and compressed conditions of the SIP. Flow was in the direction of the weave parallel to most of the fibers. The data are plotted in several standard engineering formats in order to be of maximum utility to the user. In addition to providing support to the Space Shuttle Program, these data are a source of experimental information on flow through fiberous (rather than the more usual sand bed type) porous media.

  12. Advanced turbine systems program conceptual design and product development: Task 8.1, Low-pressure drop recuperator

    SciTech Connect

    1995-09-01

    Purpose of the ATS program is to develop a new baseline for industrial gas turbine systems for the 21st century. A recuperated gas turbine cycle was selected; the eventual engine that result will utilize Solar`s Primary Surface Recuperator (PSR) technology. Besides higher thermal efficiency, other goals included lower emission, cost of power, and improved RAMD (reliability, availability, maintainability). Performance data have been obtained for the candidate heat transfer surface, and on a scaled rig. Pretest predictions of air-side and gas-side pressure drop were in very good agreement with tests results; predicted effectiveness also agreed well with experiment. A flattened tube test to determine changes of the PSR heat transfer surface profile after exposure is underway.

  13. Condensation inside tubes: Computer program for pressure drop in straight tubes (horizontal and vertical with downflow)

    NASA Astrophysics Data System (ADS)

    1993-12-01

    ESDU 93014 introduces a Fortran program that implements the calculation procedures of ESDU 90024 and 91023 respectively for vertical and horizontal cases. Those documents should be consulted for details of the empirical correlation used. Since vapor density is an important variable in the calculation and is usually available as a function of saturation temperature, the relationship between pressure and saturation temperature is required at points along the tube, although a constant value of vapor density may be used if the user wishes. The program provides options to use an Antoine or Wagner equation, or to provide a set of values of saturation pressure and temperature; for the vapor density the options are to use the ideal gas law, to provide a set of values of saturation temperature and density or to use a specific correlation equation (log density as a fraction of critical as a five term polynomial function of reciprocal reduced temperature minus one). For a wide range of pure compounds the ESDU Physical Data, Chemical Engineering Sub-series provides values of the constants in the correlation equations for saturation temperature and vapor density. The program (ESDUpac A9314) is provided on disc (uncompiled) in the software volume, and also compiled within ESDUview, a user-friendly shell running under MS DOS that prompts on screen for the input data. A worked example illustrates the use of the program and the formats of the input data and the output.

  14. Gas-Non-Newtonian liquid flow through helical coils—pressure drop and CFD analysis

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, T. K.; Biswas, A. B.; Das, S. K.

    2010-10-01

    The problem of determining the pressure losses in helical coil is important in design and analysis of the fluid machinery. It is well known that when a fluid flows through a curved pipe, the flow pattern becomes more complex than that of a straight pipe because of the generation of secondary flows due to the interaction between centrifugal and viscous forces. To understand the interaction between the two-phase gas- non-Newtonian liquid flow through helical coil tube, hydrodynamic modeling is being performed with a commercial computational fluid dynamics (CFD) code—FLUENT 6.3. The modeling has attempted to describe the results of flow visualization experiments performed in transparent helical coil tube. Both phases are first treated separately as homogeneous. Coupling is achieved through pressure and interphase exchange coefficients. Multiphase model Eulerian-Eulerian, viscous non-Newtonian laminar power law model is used to describe the interaction between the phases. The CFD modeling is compared with the experimental data.

  15. On the accuracy of CFD-based pressure drop predictions for right-angle ducts

    NASA Astrophysics Data System (ADS)

    Brankovic, Andreja

    1993-07-01

    The predictive capability of computational fluid dynamics (CFD) codes for turbulent flow through curved ducts is of significant importance to the design and performance analysis of modern rocket engine flowpaths. Code calibration and validation studies for this class of flow are desireable to estimate the performance margin and operating range of components designed using Navier-Stokes methods. Parametric experimental studies such as that of Weske (NACA ARR W-39) provided a wealth of performance data for the design of single- and compound elbow configurations with various cross-sections, curvature and aspect ratios at varying Reynolds numbers. In that work, the majority of data is presented in the form of loss coefficients, characterizing pressure losses due to duct curvature, and including losses due to wall friction. Using measured friction coefficients, losses of equivalent straight lengths of duct are subtracted, resulting in performance curves useful for design computations. These data are currently used in a CFD-based parametric study covering a broad range of operating conditions. Of particular interest for the accuracy of CFD predictions are the effects on pressure loss due to inlet boundary layer thickness (dependent on upstream development length), and the wall treatment for the turbulence equations (conventional wall functions vs. wall integration using a two-layer model). The experimental data are reassessed in the form of an error analysis, and are compared with CFD predictions for 18 computational cases. Grid-independence, grid spacing, and convergence requirements of the cases are discussed. Conclusions regarding the relative importance of the parametric variables will be presented.

  16. Condensation heat transfer and pressure drop of R-410A in a 7.0 mm O.D. microfin tube at low mass fluxes

    NASA Astrophysics Data System (ADS)

    Kim, Nae-Hyun

    2016-03-01

    R-410A condensation heat transfer and pressure drop data are provided for a 7.0 mm O.D. microfin tube at low mass fluxes (50-250 kg/m2 s). The heat transfer coefficient of the microfin tube shows a minimum behavior with the mass flux. At a low mass flux, where flow pattern is stratified, condensation induced by surface tension by microfins overwhelms condensation induced by shear, and the heat transfer coefficient decreases as mass flux increases. At a high mass flux, where flow pattern is annular, condensation induced by shear governs the heat transfer, and the heat transfer coefficient increases as mass flux increases. The pressure drop of the microfin tube is larger than that of the smooth tube at the annular flow regime. On the contrary, the pressure drop of the smooth tube is larger than that of the microfin tube at the stratified flow regime.

  17. Heat transfer and pressure drop performance of a finned-tube heat exchanger proposed for use in the NASA Lewis Altitude Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Vanfossen, G. J.

    1985-01-01

    A segment of the heat exchanger proposed for use in the NASA Lewis Altitude Wind Tunnel (AWT) facility has been tested under dry and icing conditions. The heat exchanger has the largest pressure drop of any component in the AWT loop. It is therefore critical that its performance be known at all conditions before the final design of the AWT is complete. The heat exchanger segment is tested in the NASA Lewis Icing Research Tunnel (IRT) in order to provide an icing cloud environment similar to what will be encountered in the AWT. Dry heat transfer and pressure drop data are obtained and compared to correlations available in the literature. The effects of icing sprays on heat transfer and pressure drop are also investigated.

  18. Characteristics of pebble packing and evaluation of sweep gas pressure drop into the in-pile mock-up on fusion blanket

    NASA Astrophysics Data System (ADS)

    Ishitsuka, Etsuo; Nakamichi, Masaru; Kawamura, Hiroshi; Sagawa, Hisashi; Kanzawa, Toru; Suzuki, Tatsushi; Saito, Minoru

    1994-09-01

    The characteristics of pebble packing and the sweep gas pressure drop have been investigated for the design of the in-pile mock-up in Japan Materials Testing Reactor, and the results obtained are the following. The packing fraction of single diameter pebbles is kept at constant, i.e., about 63%, under the condition that the ratio of tube inside diameter to pebble diameter is above 10. The pebble distribution in the bed is not homogeneous, i.e., the mixture of close packing and loose packing zones both in the middle of bed and near wall. The packing fraction is about 77% for two-size pebble packing consisting of Ø1 and 5 mm pebbles. The measured pressure drops agree with those predicted by the Kozeny-Carman equation within the range of (+25)-(-60)%. The pressure drop is not affected by moisture concentration (< 100 ppm) and does not change for tests lasting as long as 300 hours.

  19. Steam-explosion pretreatment of wood: Effect of chip size, acid, moisture content and pressure drop.

    PubMed

    Brownell, H H; Yu, E K; Saddler, J N

    1986-06-01

    Material balances for pentosan, lignin, and hexosan, during steam-explosion pretreatment of aspenwood, showed almost quantitative recovery of cellulose in the water-insoluble fraction. Dilute acid impregnation resulted in more selective hydrolysis of pentosan relative to undesirable pyrolysis, and gave a more accessible substrate for enzymatic hydrolysis. Thermocouple probes, located inside simulated aspenwood chips heated in 240 degrees C-saturated steam, showed rapid heating of air-dry wood, whereas green or impregnated wood heated slowly. Small chips, 3.2 mm in the fiber direction, whether green or airdry gave approximately equal rates of pentosan destruction and solubilization, and similar yields of glucose and of total reducing sugars on enzymatic hydrolysis with Trichoderma harzianum. Partial pyrolysis, destroying one third of the pentosan of aspenwood at atmospheric pressure by dry steam at 276 degrees C, gave little increase in yield of reducing sugars on enzymatic hydrolysis. Treatment with saturated steam at 240 degrees C gave essentially the same yields of glucose and of total reducing sugars, and the same yields of butanediol and ethanol on fermentation with Klebsiella pneumoniae, whether or not 80% of the steam was bled off before explosion and even if the chips remained intact, showing that explosion was unnecessary. PMID:18555395

  20. Steam-explosion pretreatment of wood: effect of chip size, acid, moisture content and pressure drop

    SciTech Connect

    Brownell, H.H.; Yu, E.K.C.; Saddler, J.N.

    1986-06-01

    Material balances for pentosan, lignin, and hexosan, during steam-explosion pretreatment of aspenwood, showed almost quantitative recovery of cellulose in the water-insoluble fraction. Dilute acid impregnation resulted in more selective hydrolysis of pentosan relative to undesirable pyrolysis, and gave a more accessible substrate for enzymatic hydrolysis. Thermocouple probes, located inside simulated aspenwood chips heated in 240 degrees C-saturated steam, showed rapid heating of air-dry wood, whereas green or impregnated wood heated slowly. Small chips, 3.2 mm in the fiber direction, whether green or air dry gave approximately equal rates of pentosan destruction and solubilization, and similar yields of glucose and of total reducing sugars on enzmatic hydrolysis with Trichoderma harzianum. Partial pyrolysis, destroying one-third of the pentosan of aspenwood at atmospheric pressure by dry steam at 276 degrees C, gave little increase in yield of reducing sugars on enzymatic hydrolysis. Treatment with saturated steam at 240 degrees C gave essentially the same yields of butanediol and ethanol on fermentation with Klebsiella pneumoniae, whether or not 80% of the steam was bled off before explosion and even if the chips remained intact, showing that explosion was unnecessary. 17 references.

  1. Effect of filtration velocity and filtration pressure drop on the bag-cleaning performance of a pulse-jet baghouse

    SciTech Connect

    Tsai, C.J.; Tsai, M.L.; Lu, H.C.

    2000-01-01

    In this study the filtration velocity and filtration pressure drop at the beginning of bag cleaning were used as experimental parameters to evaluate the bag-cleaning performance of a pulse-jet baghouse. The effective residual pressure loss was used to indicate the cleaning performance after bag cleaning. Two different test dusts, fly ash and limestone, were used. The critical cleaning indices under different operation conditions for bag cleaning were also investigated. A critical average pulse overpressure was found to exist beyond which bag-cleaning performance did not improve much. It was found the filter's final filtration resistance is an important parameter to decide whether a Venturi is necessary for a good bag-cleaning performance or not. Use of a Venturi was found to increase the average pulse overpressure for a system with a filter's final resistance coefficient greater than about 500 Pa{center{underscore}dot}s/cm. However, no Venturi is recommended when the filter's final resistance coefficient is smaller than 500 Pa{center{underscore}dot}s/cm.

  2. Vanadium and niobium additions in pressure vessel steels

    SciTech Connect

    Xu, Peiyuan.

    1992-01-01

    A statistically designed series of vanadium and niobium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in multipass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the niobium additions were in the range 0.004 to 0.06 Wt.%. GMAW processes with welding heat inputs of 3kJ/mm and 5kJ/mm and post-weld heat treatments (PWHT) at additions of microalloy elements V and Nb on multipass HAZ toughness in the as-welded and PWHT conditions was confirmed. the 50 Joule transition temperature (TT50J) for HAZs in all weld conditions correlated with maximum HAZ hardness. Increases in HAZ hardness and TT50J caused by PWHT were observed. Hence PWHT is not recommended for V/Nb microalloyed HLSA steels. The randomly distributed precipitation of V and Nb carbides (V,Nb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5-15nm, is the predominant alloy carbide precipitate morphology in these steels. Banded morphology of (V,Nb)C precipitation is rarely observed in the HAZ. The volume fraction of (V,Nb)C precipitates increases as increasing V and/or Nb contents in the experimental heats. The volume fraction of precipitates also increases with increasing the PWHT time. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality location to a higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel. An analytical study shows that the influences of additions of microalloy elements V and Nb on yield stress, [sigma][sub y8], and fracture stress, [sigma][sub f], eventuate in the increase of transition temperature in these materials.

  3. Vanadium and columbium additions in pressure vessel steels

    SciTech Connect

    Xu, P.; Somers, B.R.; Pense, A.W.

    1994-09-01

    A statistically designed series of vanadium and columbium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in post weld heat treated (PWHT) multi-pass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the columbium additions were in the range 0.004 to 0.06 Wt.% GMAW processes with welding heat inputs of 3kJ/mm and 5kJ/mm and post-weld heat treatments at 620 C for 2 10 hours were employed. A degradation of the HAZ toughness with additions of microalloy elements V and Cb in the as-welded and PWHT conditions was revealed. The 50 Joule (37 ft-lb) transition temperature (TT50J) for HAZs in all weld conditions correlated with maximum HAZ hardness. Increases in HAZ hardness and TT50J caused by PWHT were observed. Hence PWHT in some situations may not beneficial for V/Cb microalloyed HLSA steels. The randomly distributed precipitation of V and Cb carbides (V, Cb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5--15 nm, is the predominant alloy carbide precipitate morphology in these steels. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality, mid-specimen location to an off center higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel.

  4. Define and Quantify the Physics of Air Flow, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters

    SciTech Connect

    Moore, Murray E.

    2015-02-23

    Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different flow rates, temperatures and altitudes. Experimental testing will measure HEPA filter flow rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate Air) filters to purify air flow for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear Air and Gas Treatment) does not adequately describe air flow measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric air flow in ACFM (actual cubic feet per minute)compared to mass flow measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different air flow rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of flow rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different flow rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small air samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program. This is

  5. Condensation pressure drop of HFC-134a and R-404A in a smooth and micro-fin U-tube

    SciTech Connect

    Patil, Pradeep A.; Sapali, S.N.

    2011-01-15

    The frictional pressure drop during condensation of HFC-134a and R-404A in a smooth (8.56 mm ID) and micro-fin U-tubes (8.96 mm ID) are experimentally investigated. Different from previous studies, the present experiments are performed for various condensing temperatures. The test runs are done at average saturated condensing temperatures ranging from 35 C to 60 C. The mass fluxes are between 90 and 800 kg/m{sup 2}s. The experimental results indicate that the average frictional pressure drop increases with mass flux but decreases with increasing condensing temperature for both smooth and micro-fin-tubes. The average frictional pressure drops of HFC-134a and R-404A for the micro-fin-tubes were 1-1.7 and 1-2.1 times larger than that in smooth tube respectively. New correlations based on the data gathered during the experimentation for predicting frictional pressure drop are proposed for wide range of operating conditions. (author)

  6. The effect of twisted-tape width on heat transfer and pressure drop for fully developed laminar flow

    SciTech Connect

    Chakroun, W.M.; Al-Fahed, S.F.

    1996-07-01

    A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wavelengths, each with five different widths, have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 to 15 percent for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but has a more pronounced effect on heat transfer at the higher range of Reynolds number. It is recommended to use loose-fit tapes for low Reynolds number flows instead of tight-fit in the design of heat exchangers because they are easier to install and remove for cleaning purposes.

  7. Two-phase flow pressure drop and heat transfer during condensation in microchannels with uniform and converging cross-sections

    NASA Astrophysics Data System (ADS)

    Kuo, Ching Yi; Pan, Chin

    2010-09-01

    This study experimentally investigates steam condensation in rectangular microchannels with uniform and converging cross-sections and a mean hydraulic diameter of 135 µm. The steam flow in the microchannels was cooled by water cross-flowing along its bottom surface, which is different from other methods reported in the literature. The flow patterns, two-phase flow pressure drop and condensation heat transfer coefficient are determined. The microchannels with the uniform cross-section design have a higher heat transfer coefficient than those with the converging cross-section under condensation in the mist/annular flow regimes, although the latter work best for draining two-phase fluids composed of uncondensed steam and liquid water, which is consistent with the result of our previous study. From the experimental results, dimensionless correlations of condensation heat transfer for the mist and annular flow regions and a two-phase frictional multiplier are developed for the microchannels with both types of cross-section designs. The experimental data agree well with the obtained correlations, with the maximum mean absolute errors of 6.4% for the two-phase frictional multiplier and 6.0% for the condensation heat transfer.

  8. Foot Drop

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Foot Drop Information Page Table of Contents (click to ... research is being done? Clinical Trials What is Foot Drop? Foot drop describes the inability to raise ...

  9. Heat transfer and pressure drop correlations of microchannel heat exchangers with S-shaped and zigzag fins for carbon dioxide cycles

    SciTech Connect

    Ngo, Tri Lam; Kato, Yasuyoshi; Nikitin, Konstantin; Ishizuka, Takao

    2007-11-15

    A new microchannel heat exchanger (MCHE) with S-shaped fins was developed using the three-dimensional computational fluid dynamics (3D CFD) FLUENT code. The MCHE provided 6-7 times lower pressure drop while maintaining heat-transfer performance that was almost equivalent to that of a conventional MCHE with zigzag fins. This study was done to confirm the simulation results of thermal-hydraulic performance using a supercritical carbon dioxide loop, and to propose empirical correlations of Nusselt numbers and pressure-drop factors for a new MCHE with S-shaped fins and a conventional one with zigzag fins. This study is also intended to confirm the independence of Pr obtained in the previous study by widely varying Pr from 0.75 to 2.2. Experimental results show that the pressure-drop factor of the MCHEs with S-shaped fins is 4-5 times less than that of MCHE with zigzag fins, although Nu is 24-34% less, depending on the Re within its range. The Nusselt number correlations are expressed, respectively as Nu{sub S-shaped} {sub fins} = 0.1740 Re{sup 0.593}Pr{sup 0.430} and Nu{sub zigzag} {sub fins} = 0.1696 Re{sup 0.629}Pr{sup 0.317} for the MCHE with S-shaped and zigzag fins, and their pressure-drop factors are given as f{sub S-shaped} {sub fins} = 0.4545 Re{sup -0.340} and f{sub zigzag} {sub fins} = 0.1924 Re{sup -0.091}. The Nu correlation of the MCHE with S-shaped fins reproduces the experimental data of overall heat transfer coefficients with a standard deviation (1 sigma) of {+-}2.3%, although it is {+-}3.0% for the MCHE with zigzag fins. The calculated pressure drops obtained from pressure-drop factor correlations agree with the experimental data within a standard deviation of {+-}16.6% and {+-}13.5% for the MCHEs with S-shaped and zigzag fins, respectively. (author)

  10. Measurement and modelling of forced convective heat transfer coefficient and pressure drop of Al2O3- and SiO2-water nanofluids

    NASA Astrophysics Data System (ADS)

    Julia, J. E.; Hernández, L.; Martínez-Cuenca, R.; Hibiki, T.; Mondragón, R.; Segarra, C.; Jarque, J. C.

    2012-11-01

    Forced convective heat transfer coefficient and pressure drop of SiO2- and Al2O3-water nanofluids were characterized. The experimental facility was composed of thermal-hydraulic loop with a tank with an immersed heater, a centrifugal pump, a bypass with a globe valve, an electromagnetic flow-meter, a 18 kW in-line pre-heater, a test section with band heaters, a differential pressure transducer and a heat exchanger. The test section consists of a 1000 mm long aluminium pipe with an inner diameter of 31.2 mm. Eighteen band heaters were placed all along the test section in order to provide a uniform heat flux. Heat transfer coefficient was calculated measuring fluid temperature using immersed thermocouples (Pt100) placed at both ends of the test section and surface thermocouples in 10 axial locations along the test section (Pt1000). The measurements have been performed for different nanoparticles (Al2O3 and SiO2 with primary size of 11 nm and 12 nm, respectively), volume concentrations (1% v., 5% v.), and flow rates (3 103Re<105). Maximum heat transfer coefficient enhancement (300%) and pressure drop penalty (1000%) is obtained with 5% v. SiO2 nanofluid. Existing correlations can predict, at least in a first approximation, the heat transfer coefficient and pressure drop of nanofluids if thermal conductivity, viscosity and specific heat were properly modelled.

  11. Drop Coalescence during Emulsion Formation in a High-Pressure Homogenizer for Tetradecane-in-Water Emulsion Stabilized by Sodium Dodecyl Sulfate.

    PubMed

    Narsimhan, Ganesan; Goel, Parul

    2001-06-15

    The present study investigates the effects of homogenizer pressure, surfactant concentration, ionic strength, and dispersed phase fraction on the coalescence rate of tetradecane-in-water emulsions during their formation in a high-pressure homogenizer. Experiments were conducted in a recirculating system consisting of a Rannie laboratory-scale single-stage homogenizer and a stirred vessel for tetradecane-in-water emulsions stabilized by sodium dodecyl sulfate (SDS). The initial evolution of the number concentration of droplets in the stirred tank was measured when subjected to a negative stepchange in the homogenizer pressure. The average drop coalescence rate constant in the homogenizer was inferred by fitting the experimental evolution of the number concentration of drops to a simple model accounting for the coalescence in the homogenizer under the assumption of a quasi steady state in the homogenizer. The residence time of the emulsion in the homogenizer was evaluated from the analysis of radial turbulent flow between disks. The step down homogenizer pressure was varied in the range 20.7-48.3 MPa, the drop size in the range 174-209 nm, the dispersed phase fraction in the range 5%-15%, SDS concentration in the range 0.0033-0.25 wt%, and ionic strength in the range 0.01-0.1 M. The coalescence rate constants were found to be in the range from 3.34x10(-17) to 2.43x10(-16) m(3) s(-1). The coalescence rate constant was found to be higher for higher homogenizer pressures, smaller drop sizes, lower dispersed phase fractions, and lower SDS concentrations and was insensitive to variations in ionic strength. Copyright 2001 Academic Press. PMID:11374938

  12. Turbulent Kinetic Energy Measurement Using Phase Contrast MRI for Estimating the Post-Stenotic Pressure Drop: In Vitro Validation and Clinical Application

    PubMed Central

    Ha, Hojin; Kim, Guk Bae; Kweon, Jihoon; Huh, Hyung Kyu; Lee, Sang Joon; Koo, Hyun Jung; Kang, Joon-Won; Lim, Tae-Hwan; Kim, Dae-Hee; Kim, Young-Hak

    2016-01-01

    Background Although the measurement of turbulence kinetic energy (TKE) by using magnetic resonance imaging (MRI) has been introduced as an alternative index for quantifying energy loss through the cardiac valve, experimental verification and clinical application of this parameter are still required. Objectives The goal of this study is to verify MRI measurements of TKE by using a phantom stenosis with particle image velocimetry (PIV) as the reference standard. In addition, the feasibility of measuring TKE with MRI is explored. Methods MRI measurements of TKE through a phantom stenosis was performed by using clinical 3T MRI scanner. The MRI measurements were verified experimentally by using PIV as the reference standard. In vivo application of MRI-driven TKE was explored in seven patients with aortic valve disease and one healthy volunteer. Transvalvular gradients measured by MRI and echocardiography were compared. Results MRI and PIV measurements of TKE are consistent for turbulent flow (0.666 < R2 < 0.738) with a mean difference of −11.13 J/m3 (SD = 4.34 J/m3). Results of MRI and PIV measurements differ by 2.76 ± 0.82 cm/s (velocity) and −11.13 ± 4.34 J/m3 (TKE) for turbulent flow (Re > 400). The turbulence pressure drop correlates strongly with total TKE (R2 = 0.986). However, in vivo measurements of TKE are not consistent with the transvalvular pressure gradient estimated by echocardiography. Conclusions These results suggest that TKE measurement via MRI may provide a potential benefit as an energy-loss index to characterize blood flow through the aortic valve. However, further clinical studies are necessary to reach definitive conclusions regarding this technique. PMID:26978529

  13. Characterisation of heat transfer and pressure drop in condensation processes within mini-channel tubes with last generation of refrigerant fluids

    NASA Astrophysics Data System (ADS)

    Lopez Belchi, D. Alejandro

    Heat exchanger developments are driven by energetic efficiency increase and emissionreduction. To reach the standards new system are required based on mini-channels. Mini-channels can be described as tubes with one or more ports extruded in aluminiumwith hydraulic diameter are in the range of 0.2 to 3 mm. Its use in refrigeration systemsfor some years ago is a reality thanks to the human ability to made micro-scale systems.Some heat exchanger enterprises have some models developed specially for their use inautomotive sector, cooling sector, and industrial refrigeration without having a deepknowledge of how these reduced geometries affect the most important parameters suchas pressure drop and the heat transfer coefficient. To respond to this objective, an exhaustive literature review of the last two decades hasbeen performed to determinate the state of the research. Between all the publications,several models have been selected to check the predicting capacities of them becausemost of them were developed for single port mini-channel tubes. Experimentalmeasurements of heat transfer coefficient and frictional pressure drop were recorded inan experimental installation built on purpose at the Technical University of Cartagena.Multiple variables are recorded in this installation in order to calculate local heattransfer coefficient in two-phase condensing flow within mini-channels. Both pressure drop and heat transfer coefficient experimental measurements arecompared to the previously mentioned models. Most of them capture the trend correctlybut others fail predicting experimental data. These differences can be explained by theexperimental parameters considered during the models development. In some cases themodels found in the literature were developed specific conditions, consequently theirpredicting capacities are restricted. As main contributions, this thesis provides new modelling tools for mini-channelscondensing pressure drop and heat transfer coefficient

  14. A critical review of forced convection heat transfer and pressure drop of Al2O3, TiO2 and CuO nanofluids

    NASA Astrophysics Data System (ADS)

    Khurana, Deepak; Choudhary, Rajesh; Subudhi, Sudhakar

    2016-04-01

    Nanofluid is the colloidal suspension of nanosized solid particles like metals or metal oxides in some conventional fluids like water and ethylene glycol. Due to its unique characteristics of enhanced heat transfer compared to conventional fluid, it has attracted the attention of research community. The forced convection heat transfer of nanofluid is investigated by numerous researchers. This paper critically reviews the papers published on experimental studies of forced convection heat transfer and pressure drop of Al2O3, TiO2 and CuO based nanofluids dispersed in water, ethylene glycol and water-ethylene glycol mixture. Most of the researchers have shown a little rise in pressure drop with the use of nanofluids in plain tube. Literature has reported that the pumping power is appreciably high, only at very high particle concentration i.e. more than 5 %. As nanofluids are able to enhance the heat transfer at low particle concentrations so most of the researchers have used less than 3 % volume concentration in their studies. Almost no disagreement is observed on pressure drop results of different researchers. But there is not a common agreement in magnitude and mechanism of heat transfer enhancement. Few studies have shown an anomalous enhancement in heat transfer even at low particle concentration. On the contrary, some researchers have shown little heat transfer enhancement at the same particle concentration. A large variation (2-3 times) in Nusselt number was observed for few studies under similar conditions.

  15. Carbon dioxide and R410A flow boiling heat transfer, pressure drop, and flow pattern in horizontal tubes at low temperatures

    NASA Astrophysics Data System (ADS)

    Park, Chang Yong

    Carbon dioxide (CO2) has been seriously considered as an alternate refrigerant for HCFC and HFC fluids, due to the increasing interest of environmentally safe refrigerants in air-conditioning and refrigeration systems. In this study, CO2 flow boiling heat transfer coefficients and pressure drop are measured in macro-scale (6.1 and 3.5 mm) tubes at evaporation temperatures of -15 and -30°C. The measured results show that the nucleate boiling is a main heat transfer mechanism in the 6.1 mm tube and the contribution of convective boiling becomes greater with the decrease of tube diameters and the increase of mass fluxes. The surface roughness of the 6.1 and 3.5 mm tube are presented by SEM and AFM images and surface profiles, and it is shown that the rougher surface of the 6.1 mm tube can affect the flow boiling heat transfer. The CO2 heat transfer coefficients and pressure drop are measured in a mini-scale (0.89 mm) multi-ported tube at the evaporation temperature of -30°C. Also, R410A and R22 flow boiling heat transfer coefficients and pressure drop in a macro-scale (6.1 mm) tube were measured, and they are compared with CO2. This comparison presents that the CO2 flow boiling heat transfer coefficients are higher than R410A and R22 at low vapor qualities, and CO2 pressure drop is significantly lower than R410A and R22. This advantageous characteristic for CO2 could be explained by properties such as surface tension, reduced pressure, and the density ratio of liquid to vapor. The prediction of heat transfer coefficients and pressure drop was performed by general correlations and the calculation results are compared with measured values. Two-phase flow patterns were visualized for CO2 and R410A in the 6 and 3 mm glass tubes, and they are compared with the Weisman et al. and the Wojtan et al. flow pattern maps. The flow pattern maps can determine the flow patterns relatively well, except the transition from intermittent to annular flow.

  16. Additional flow quality measurements in the Langley Research Center 8-Foot Transonic Pressure Tunnel

    NASA Technical Reports Server (NTRS)

    Brooks, J. D.; Stainback, P. C.; Brooks, C. W., Jr.

    1980-01-01

    Additional tests were conducted to further define the disturbance characteristics of the Langley 8-Foot Transonic Pressure Tunnel. Measurements were made in the settling chamber with hot wire probes and in the test section with pressure transducers when various methods were used to choke the flow. In addition to presenting rms values measured at various locations and tunnel condition, autocorrelations and cross correlation data are also presented.

  17. Effect of airstream velocity on mean drop diameters of water sprays produced by pressure and air atomizing nozzles. [for combustion studies

    NASA Technical Reports Server (NTRS)

    Ingebo, R. D.

    1977-01-01

    A scanning radiometer was used to determine the effect of airstream velocity on the mean drop diameter of water sprays produced by pressure atomizing and air atomizing fuel nozzles used in previous combustion studies. Increasing airstream velocity from 23 to 53.4 meters per second reduced the Sauter mean diameter by approximately 50 percent with both types of fuel nozzles. The use of a sonic cup attached to the tip of an air assist nozzle reduced the Sauter mean diameter by approximately 40 percent. Test conditions included airstream velocities of 23 to 53.4 meters per second at 293 K and atmospheric pressure.

  18. 49 CFR 173.301b - Additional general requirements for shipment of UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... REGULATIONS SHIPPERS-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.301b Additional general requirements for shipment of UN pressure receptacles. (a) General. The... 49 Transportation 2 2013-10-01 2013-10-01 false Additional general requirements for shipment of...

  19. 49 CFR 173.301b - Additional general requirements for shipment of UN pressure receptacles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... REGULATIONS SHIPPERS-GENERAL REQUIREMENTS FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging § 173.301b Additional general requirements for shipment of UN pressure receptacles. (a) General. The... 49 Transportation 2 2010-10-01 2010-10-01 false Additional general requirements for shipment of...

  20. Micro-explosion of compound drops

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Kuei; Lin, Ta-Hui

    2014-08-01

    Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NOx reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NOx. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive

  1. High-pressure high-temperature synthesis of magnesium diboride with different additions

    NASA Astrophysics Data System (ADS)

    Prikhna, Tatiana; Gawalek, Wolfgang; Savchuk, Yaroslav; Sergienko, Nina; Moshchil, Viktor; Dub, Sergey; Sverdun, Vladimir; Kovalev, Leo; Penkin, Vladimir; Zeisberger, Matthias; Wendt, Michael; Fuchs, Gunter; Habisreuther, Tobias; Litzkendorf, Doris; Nagorny, Peter; Melnikov, Vladimir

    2007-09-01

    An increase of the critical current density in high-pressure synthesized (at 2 GPa, 800-900 °C) MgB2 was observed when some amount (2-10%) of powdered Ta, Ti or Zr was added to the initial mixture of Mg and B. As a result of high-pressure synthesis, the metallic additives transformed into hydrides, so the absorbed impurity hydrogen coming most likely from the materials of a high-pressure cell surrounded the synthesized samples. Blocks of high-pressure synthesized MgB2 (with Ti additions) were for the first time used in an SC electromotor that demonstrated the efficiency similar to that of MT-YBCO bulk (at the same working temperature 15-20 K).

  2. Effect of magnetic field on the forced convection heat transfer and pressure drop of a magnetic nanofluid in a miniature heat sink

    NASA Astrophysics Data System (ADS)

    Ashjaee, Mehdi; Goharkhah, Mohammad; Khadem, Leila Azizi; Ahmadi, Reza

    2014-12-01

    The effect of an external magnetic field on the forced convection heat transfer and pressure drop of water based Fe3O4 nanofluid (ferrofluid) in a miniature heat sink is studied experimentally. The heat sink with the dimensions of 40 mm (L) × 40 mm (W) × 10 mm (H) consists of an array of five circular channels with diameter and length of 4 and 40 mm, respectively. It is heated from the bottom surface with a constant heat flux while the other surfaces are insulated. The heat sink is also influenced by an external magnetic field generated by an electromagnet. The local convective coefficients are measured at various flow rates (200 < Re < 900), magnetic field intensities (B < 1,400 G), and particle volume fractions (φ = 0.5, 1, 2 and 3 %). Results show that using ferrofluid results in a maximum of 14 % improvement in heat transfer compared to the pure water, in the absence of magnetic field. This value grows up to 38 % when a magnetic field with the strength of 1,200 G is applied to the ferrofluid. On the other hand, it is observed that the significant heat transfer enhancement due to the magnetic field is always accompanied by a pressure drop penalty. The optimum operating condition is obtained based on the maximum heat transfer enhancement per pressure loss.

  3. Experimental sizing and assessment of two-phase pressure drop correlations for a capillary tube with transcritical and subcritical carbon dioxide flow

    NASA Astrophysics Data System (ADS)

    Trinchieri, R.; Boccardi, G.; Calabrese, N.; Celata, G. P.; Zummo, G.

    2014-04-01

    In the last years, CO2 was proposed as an alternative refrigerant for different refrigeration applications (automotive air conditioning, heat pumps, refrigerant plants, etc.) In the case of low power refrigeration applications, as a household refrigerator, the use of too expensive components is not economically sustainable; therefore, even if the use of CO2 as the refrigerant is desired, it is preferable to use conventional components as much as possible. For these reasons, the capillary tube is frequently proposed as expansion system. Then, it is necessary to characterize the capillary in terms of knowledge of the evolving mass flow rate and the associate pressure drop under all possible operative conditions. For this aim, an experimental campaign has been carried out on the ENEA test loop "CADORE" to measure the performance of three capillary tubes having same inner diameter (0.55 mm) but different lengths (4, 6 and 8 meters). The test range of inlet pressure is between about 60 and 110 bar, whereas external temperatures are between about 20 to 42 °C. The two-phase pressure drop through the capillary tube is detected and experimental values are compared with the predictions obtained with the more widely used correlations available in the literature. Correlations have been tested over a wide range of variation of inlet flow conditions, as a function of different inlet parameters.

  4. Experimental study on heat transfer and pressure drop characteristics of four types of plate fin-and-tube heat exchanger surfaces

    NASA Astrophysics Data System (ADS)

    Kang, H. J.; Li, W.; Li, H. Z.; Xin, R. C.; Tao, W. Q.

    1994-03-01

    In this paper, air side heat transfer and pressure drop characteristics of twelve three-row plate fin-and-tube heat exchanger cores of four types of fin configurations have been experimentally investigated. The heat transfer and friction factor correlations for the twelve cores are provided in a wide range of Reynolds number. It is found that in the range of Reynolds number tested, the Nusselt number of the slotted fin surface is the largest and that of the plain plate fin is the lowest while the Nusselt numbers of two types of wavy fins are somewhere in between.

  5. Study on measurement of the coal powder concentration in pneumatic pipes of a boiler with relationship between air velocity and pressure drop

    SciTech Connect

    Pan, W.; Shen, F.; Lin, W.; Chen, L.; Zhang, D.; Wang, Q.; Ke, J.; Quan, W.

    1999-07-01

    According to the theoretical relationship between air velocity and pressure drop in different solid-air mass flow in vertical pipes with the condition of upward air-solid flowing, the experimental research on measuring the coal powder concentration is directed against the pneumatic pipes of a boiler's combustion system in the energy industry. Through analyzing the experimental results, a mathematical model for measuring the coal powder concentration in pneumatic pipes is obtained. Then, the error analysis is done, and the method of on-line measurement and its function are provided.

  6. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  7. Drop dynamics

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.

    1981-01-01

    The drop dynamics module is a Spacelab-compatible acoustic positioning and control system for conducting drop dynamics experiments in space. It consists basically of a chamber, a drop injector system, an acoustic positioning system, and a data collection system. The principal means of collecting data is by a cinegraphic camera. The drop is positioned in the center of the chamber by forces created by standing acoustic waves generated in the nearly cubical chamber (about 12 cm on a side). The drop can be spun or oscillated up to fission by varying the phse and amplitude of the acoustic waves. The system is designed to perform its experiments unattended, except for start-up and shutdown events and other unique events that require the attention of the Spacelab payload specialist.

  8. Noninvasive estimation of transmitral pressure drop across the normal mitral valve in humans: importance of convective and inertial forces during left ventricular filling

    NASA Technical Reports Server (NTRS)

    Firstenberg, M. S.; Vandervoort, P. M.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

    2000-01-01

    OBJECTIVES: We hypothesized that color M-mode (CMM) images could be used to solve the Euler equation, yielding regional pressure gradients along the scanline, which could then be integrated to yield the unsteady Bernoulli equation and estimate noninvasively both the convective and inertial components of the transmitral pressure difference. BACKGROUND: Pulsed and continuous wave Doppler velocity measurements are routinely used clinically to assess severity of stenotic and regurgitant valves. However, only the convective component of the pressure gradient is measured, thereby neglecting the contribution of inertial forces, which may be significant, particularly for nonstenotic valves. Color M-mode provides a spatiotemporal representation of flow across the mitral valve. METHODS: In eight patients undergoing coronary artery bypass grafting, high-fidelity left atrial and ventricular pressure measurements were obtained synchronously with transmitral CMM digital recordings. The instantaneous diastolic transmitral pressure difference was computed from the M-mode spatiotemporal velocity distribution using the unsteady flow form of the Bernoulli equation and was compared to the catheter measurements. RESULTS: From 56 beats in 16 hemodynamic stages, inclusion of the inertial term ([deltapI]max = 1.78+/-1.30 mm Hg) in the noninvasive pressure difference calculation significantly increased the temporal correlation with catheter-based measurement (r = 0.35+/-0.24 vs. 0.81+/-0.15, p< 0.0001). It also allowed an accurate approximation of the peak pressure difference ([deltapc+I]max = 0.95 [delta(p)cathh]max + 0.24, r = 0.96, p<0.001, error = 0.08+/-0.54 mm Hg). CONCLUSIONS: Inertial forces are significant components of the maximal pressure drop across the normal mitral valve. These can be accurately estimated noninvasively using CMM recordings of transmitral flow, which should improve the understanding of diastolic filling and function of the heart.

  9. Experimental investigation of two-phase flow pressure drop transients in polymer electrolyte membrane fuel cell reactant channels and their impact on the cell performance

    NASA Astrophysics Data System (ADS)

    Banerjee, Rupak; Kandlikar, Satish G.

    2014-12-01

    Fuel cells experience transients, which constitute a significant part of the drive cycle. Fuel cell response during these transients depends on the rates of reaction kinetics as well as mass transport delays. In the current work, an in situ setup is used to investigate the effect of changing load and temperature conditions on the two-phase flow in the fuel cell. Pressure drop and voltage response from the cell are used to characterize the two-phase flow and performance of the cell. The effect of changing load is simulated by changing the current by 20 A cm-2 (0.4 A cm-2) over a time period of 300 s, while the effect of changing cell temperature is studied by increasing/decreasing the cell temperature by 40 °C over 900 s. The results show that several minutes are required after a transient event for the two-phase flow to return to a new steady state condition. Transient effects are more prominent at the lower temperature of 40 °C, at which condition there is more liquid water present in the channels. Overshoot behavior, commonly seen in current and voltage response from fuel cells, has been observed for two-phase pressure drop during transient load changes.

  10. Two-Phase Frictional Pressure Drop Multipliers for SUVA R-134a Flowing in a Rectangular Duct

    SciTech Connect

    P Vassallo; K Keller

    2004-12-13

    The adiabatic two-phase frictional multipliers for SUVA, R-134a flowing in a rectangular duct (with D{sub H} = 4.8 mm) have been measured for 3 nominal system pressures (0.9 MPa, 1.38 MPa and 2.41 MPa) and 3 nominal mass fluxes (510, 1020 and 2040 kg/m{sup 2}/s). The data is compared with several classical correlations to assess their predictive capabilities. The Lockhart-Martinelli model gives reasonable results at the lowest pressure and mass flux, near the operating range of most refrigeration systems, but gives increasingly poor comparisons as the pressure and mass flux is increased. The Chisholm B-coefficient model is found to best predict the data over the entire range of test conditions; however, there is significant disagreement at the highest pressure tested (with the model over predicting the data upwards of 100% for some cases). The data shows an increased tendency toward homogeneous flow as the pressure and flow rate are increased, and in fact the homogeneous model best predicts the bulk of the data at the highest pressure tested.

  11. Methods of Measuring Vapor Pressures of Lubricants With Their Additives Using TGA and/or Microbalances

    NASA Technical Reports Server (NTRS)

    Scialdone, John J.; Miller, Michael K.; Montoya, Alex F.

    1996-01-01

    The life of a space system may be critically dependent on the lubrication of some of its moving parts. The vapor pressure, the quantity of the available lubricant, the temperature and the exhaust venting conductance passage are important considerations in the selection and application of a lubricant. In addition, the oil additives employed to provide certain properties of low friction, surface tension, antioxidant and load bearing characteristics, are also very important and need to be known with regard to their amounts and vapor pressures. This paper reports on the measurements and analyses carried out to obtain those parameters for two often employed lubricants, the Apiezon(TM)-C and the Krytox(TM) AB. The measurements were made employing an electronic microbalance and a thermogravimetric analyzer (TGA) modified to operate in a vacuum. The results have been compared to other data on these oils when available. The identification of the mass fractions of the additives in the oil and their vapor pressures as a function of the temperature were carried out. These may be used to estimate the lubricant life given its quantity and the system vent exhaust conductance. It was found that the Apiezon(TM)-C has three main components with different rates of evaporation while the Krytox(TM) did not indicate any measurable additive.

  12. High Pressure, Transport Properties of Fluids: Theory and Data from Levitated Fluid-Drops at Combustion-Relevant Temperatures

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Ohaska, K.

    2001-01-01

    The objective of this investigation is to derive a set of consistent mixing rules for calculating diffusivities and thermal diffusion factors over a thermodynamic regime encompassing the subcritical and supercritical ranges. These should serve for modeling purposes, and therefore for accurate simulations of high pressure phenomena such as fluid disintegration, turbulent flows and sprays. A particular consequence of this work will be the determination of effective Lewis numbers for supercritical conditions, thus enabling the examination of the relative importance of heat and mass transfer at supercritical pressures.

  13. Clinical evaluation of clobetasone butyrate eye drops in the treatment of anterior uveitis and its effects on intraocular pressure.

    PubMed Central

    Eilon, L A; Walker, S R

    1981-01-01

    Clobetasone butyrate has been formulated as a new steroid preparation of use in ophthalmology and has been compared with prednisolone phosphate and betamethasone phosphate in the treatment of anterior uveitis. The results from 4 double-blind, between-patient studies have shown that all 3 treatments are effective in reducing the signs and symptoms of this intraocular disease. 87% of those patients receiving clobetasone butyrate had a good or satisfactory response, but no differences in therapeutic efficacy were observed between these 3 steroid treatments. Clobetasone butyrate had little effect on intraocular pressure when compared with dexamethasone or hydrocortisone, both of which cause a significant rise in intraocular pressure. PMID:7028089

  14. Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

    NASA Technical Reports Server (NTRS)

    Einstein, Thomas H.

    1961-01-01

    Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

  15. Fabrication and characterization of Si3N4 ceramics without additives by high pressure hot pressing

    NASA Technical Reports Server (NTRS)

    Shimada, M.; Tanaka, A.; Yamada, T.; Koizumi, M.

    1984-01-01

    High pressure hot-pressing of Si3N4 without additives was performed using various kinds of Si3N4 powder as starting materials, and the relation between densification and alpha-beta phase transformation was studied. The temperature dependences of Vickers microhardness and fracture toughness were also examined. Densification of Si3N4 was divided into three stages, and it was found that densification and phase transformation of Si3N4 under pressure were closely associated. The results of the temperature dependence of Vickers microhardness indicated that the high-temperature hardness was strongly influenced not only by the density and microstructure of sintered body but also by the purity of starting powder. The fracture toughness values of Si3N4 bodies without additives were 3.29-4.39 MN/m to the 3/2 power and independent of temperature up to 1400 C.

  16. EVAPORATION: a new vapour pressure estimation methodfor organic molecules including non-additivity and intramolecular interactions

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Ceulemans, K.; Müller, J.-F.

    2011-09-01

    We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects), a method to predict (subcooled) liquid pure compound vapour pressure p0 of organic molecules that requires only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T) is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: aldehydes, ketones, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA).

  17. Modeling the shear rate and pressure drop in a hydrodynamic cavitation reactor with experimental validation based on KI decomposition studies.

    PubMed

    Badve, Mandar P; Alpar, Tibor; Pandit, Aniruddha B; Gogate, Parag R; Csoka, Levente

    2015-01-01

    A mathematical model describing the shear rate and pressure variation in a complex flow field created in a hydrodynamic cavitation reactor (stator and rotor assembly) has been depicted in the present study. The design of the reactor is such that the rotor is provided with surface indentations and cavitational events are expected to occur on the surface of the rotor as well as within the indentations. The flow characteristics of the fluid have been investigated on the basis of high accuracy compact difference schemes and Navier-Stokes method. The evolution of streamlining structures during rotation, pressure field and shear rate of a Newtonian fluid flow have been numerically established. The simulation results suggest that the characteristics of shear rate and pressure area are quite different based on the magnitude of the rotation velocity of the rotor. It was observed that area of the high shear zone at the indentation leading edge shrinks with an increase in the rotational speed of the rotor, although the magnitude of the shear rate increases linearly. It is therefore concluded that higher rotational speeds of the rotor, tends to stabilize the flow, which in turn results into less cavitational activity compared to that observed around 2200-2500RPM. Experiments were carried out with initial concentration of KI as 2000ppm. Maximum of 50ppm of iodine liberation was observed at 2200RPM. Experimental as well as simulation results indicate that the maximum cavitational activity can be seen when rotation speed is around 2200-2500RPM. PMID:24924259

  18. A Numerical Procedure for Flow Distribution and Pressure Drops for U and Z Type Configurations Plate Heat Exchangers with Variable Coefficients

    NASA Astrophysics Data System (ADS)

    López, R.; Lecuona, A.; Ventas, R.; Vereda, C.

    2012-11-01

    In Plate Heat Exchangers it is important to determine the flow distribution and pressure drops, because they affect directly the performance of a heat exchanger [1]. This work proposes an incompressible, one-dimensional, steady state, discrete model allowing for variable overall momentum coefficients to determine these magnitudes. The model consists on a modified version of the Bajura and Jones [2] model for dividing and combining flow manifolds. The numerical procedure is based on the finite differences approximation approach proposed by Datta and Majumdar [3]. A linear overall momentum coefficient distribution is used in the dividing manifold, but the model is not limited to linear distributions. Comparisons are made with experimental, numerical and analytical data, yielding good results.

  19. Heat transfer and pressure drop in a compact pin-fin heat exchanger with pin orientation at 18 deg to the flow direction

    NASA Technical Reports Server (NTRS)

    Olson, D. A.

    1991-01-01

    The heat transfer and pressure drop characteristics of a novel, compact heat exchanger in helium gas were measured at 3.5 MPa and Reynolds numbers of 450 to 12,000. The pin-fin specimen consisted of pins, 0.51 mm high and spaced 2.03 mm on centers, spanning a channel through which the helium flows; the angle of the row of pins to the flow direction was 18 deg. The specimen was radiatively heated on the top side at heat fluxes up to 74 W/sq cm and insulated on the back side. Correlations were developed for the friction factor and Nusselt number. The Nusselt number compares favorably to those of past studies of staggered pin-fins, when the measured temperatures are extrapolated to the temperature of the wall-fluid interface.

  20. Parallelization of Catalytic Packed-Bed Microchannels with Pressure-Drop Microstructures for Gas-Liquid Multiphase Reactions

    NASA Astrophysics Data System (ADS)

    Murakami, Sunao; Ohtaki, Kenichiro; Matsumoto, Sohei; Inoue, Tomoya

    2012-06-01

    High-throughput and stable treatments are required to achieve the practical production of chemicals with microreactors. However, the flow maldistribution to the paralleled microchannels has been a critical problem in achieving the productive use of multichannel microreactors for multiphase flow conditions. In this study, we newly designed and fabricated a glass four-channel catalytic packed-bed microreactor for the scale-up of gas-liquid multiphase chemical reactions. We embedded microstructures generating high pressure losses at the upstream side of each packed bed, and experimentally confirmed the efficacy of the microstructures in decreasing the maldistribution of the gas-liquid flow to the parallel microchannels.

  1. Overall heat transfer coefficient and pressure drop in a typical tubular exchanger employing alumina nano-fluid as the tube side hot fluid

    NASA Astrophysics Data System (ADS)

    Kabeel, A. E.; Abdelgaied, Mohamed

    2015-08-01

    Nano-fluids are used to improve the heat transfer rates in heat exchangers, especially; the shell-and-tube heat exchanger that is considered one of the most important types of heat exchangers. In the present study, an experimental loop is constructed to study the thermal characteristics of the shell-and-tube heat exchanger; at different concentrations of Al2O3 nonmetallic particles (0.0, 2, 4, and 6 %). This material concentrations is by volume concentrations in pure water as a base fluid. The effects of nano-fluid concentrations on the performance of shell and tube heat exchanger have been conducted based on the overall heat transfer coefficient, the friction factor, the pressure drop in tube side, and the entropy generation rate. The experimental results show that; the highest heat transfer coefficient is obtained at a nano-fluid concentration of 4 % of the shell side. In shell side the maximum percentage increase in the overall heat transfer coefficient has reached 29.8 % for a nano-fluid concentration of 4 %, relative to the case of the base fluid (water) at the same tube side Reynolds number. However; in the tube side the maximum relative increase in pressure drop has recorded the values of 12, 28 and 48 % for a nano-material concentration of 2, 4 and 6 %, respectively, relative to the case without nano-fluid, at an approximate value of 56,000 for Reynolds number. The entropy generation reduces with increasing the nonmetallic particle volume fraction of the same flow rates. For increase the nonmetallic particle volume fraction from 0.0 to 6 % the rate of entropy generation decrease by 10 %.

  2. Overall heat transfer coefficient and pressure drop in a typical tubular exchanger employing alumina nano-fluid as the tube side hot fluid

    NASA Astrophysics Data System (ADS)

    Kabeel, A. E.; Abdelgaied, Mohamed

    2016-08-01

    Nano-fluids are used to improve the heat transfer rates in heat exchangers, especially; the shell-and-tube heat exchanger that is considered one of the most important types of heat exchangers. In the present study, an experimental loop is constructed to study the thermal characteristics of the shell-and-tube heat exchanger; at different concentrations of Al2O3 nonmetallic particles (0.0, 2, 4, and 6 %). This material concentrations is by volume concentrations in pure water as a base fluid. The effects of nano-fluid concentrations on the performance of shell and tube heat exchanger have been conducted based on the overall heat transfer coefficient, the friction factor, the pressure drop in tube side, and the entropy generation rate. The experimental results show that; the highest heat transfer coefficient is obtained at a nano-fluid concentration of 4 % of the shell side. In shell side the maximum percentage increase in the overall heat transfer coefficient has reached 29.8 % for a nano-fluid concentration of 4 %, relative to the case of the base fluid (water) at the same tube side Reynolds number. However; in the tube side the maximum relative increase in pressure drop has recorded the values of 12, 28 and 48 % for a nano-material concentration of 2, 4 and 6 %, respectively, relative to the case without nano-fluid, at an approximate value of 56,000 for Reynolds number. The entropy generation reduces with increasing the nonmetallic particle volume fraction of the same flow rates. For increase the nonmetallic particle volume fraction from 0.0 to 6 % the rate of entropy generation decrease by 10 %.

  3. Effects of extreme pressure additive chemistry on rolling element bearing surface durability

    SciTech Connect

    Evans, Ryan D.; Nixon, H. P.; Darragh, Craig V.; Howe, Jane Y; Coffey, Dorothy W

    2007-01-01

    Lubricant additives have been known to affect rolling element bearing surface durability for many years. Tapered roller bearings were used in fatigue testing of lubricants formulated with gear oil type additive systems. These systems have sulfur- and phosphoruscontaining compounds used for gear protection as well as bearing lubrication. Several variations of a commercially available base additive formulation were tested having modified sulfur components. The variations represent a range of ''active'' extreme pressure (EP) chemistries. The bearing fatigue test results were compared with respect to EP formulation and test conditions. Inner ring near-surface material in selected test bearings was evaluated on two scales: the micrometer scale using optical metallography and the nanometer scale using transmission electron microscopy (TEM). Focused-ion beam (FIB) techniques were used for TEM specimen preparation. Imaging and chemical analysis of the bearing samples revealed near-surface material and tribofilm characteristics. These results are discussed with respect to the relative fatigue lives.

  4. An additional uncertainty of the throughput generated by the constant pressure gas flowmeter

    NASA Astrophysics Data System (ADS)

    Peksa, L.; Gronych, T.; Řepa, P.; Wild, J.; Tesař, J.; Pražák, D.; Krajíček, Z.; Vičar, M.

    2008-03-01

    The lower range limit of constant pressure gas flowmeters is about 10-8 Pa×m3/s. Detrimental gas throughputs caused by leaks and gassing from surfaces prevent from its decrease. Even if the flowmeter is entirely vacuum tight the throughput caused by the outgassing from surfaces can be sufficiently reduced only by pumping at elevated temperature. It can be performed with the flowmeters using directly driven bellows or diaphragm bellows in the volume displacers. Despite it, the lower range limit can hardly be decreased more than several ten times with up to now known designs. An additional uncertainty caused by the difference in pressure at the initial and final instant of measurement will increase at generating small throughputs to the extent that it will kill the measurement.

  5. Pressure drop and heat transfer in turbulent non-Newtonian pipe flow of advanced energy transmission fluids

    NASA Astrophysics Data System (ADS)

    Choi, U. S.; Liu, K. V.; Kasza, K. E.

    1988-03-01

    Argonne National Laboratory (ANL), under sponsorship of the U.S. Department of Energy, is making significant progress on the development of advanced energy transmission fluids for thermal systems, in particular district heating and cooling systems. ANL has identified two concepts for developing advanced energy transmission fluids. Tests have been conducted at ANL to prove these concepts. This paper presents experimental results and discusses the degradation behavior of linear polymer additives and the flow and heat transfer characteristics of non-melting slurry flows. The experimental data obtained in this study provide support for the use of friction reducing additives and slurries in thermal system applications.

  6. Liquid drops impacting superamphiphobic coatings.

    PubMed

    Deng, Xu; Schellenberger, Frank; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen

    2013-06-25

    The dynamics of liquid drops impacting superamphiphobic coatings is studied by high-speed video microscopy. Superamphiphobic coatings repel water and oils. The coating consists of a fractal-like hydrophobized silica network. Mixtures of ethanol-water and glycerin-water are chosen to investigate the influence of interfacial tension and viscosity on spreading and retraction dynamics. Drop spreading is dominated by inertia. At low impact velocity, the drops completely rebound. However, the contact time increases with impact velocity, whereas the restitution coefficient decreases. We suggest that the drop temporarily impales the superamphiphobic coating, although the drop completely rebounds. From an estimate of the pressure, it can be concluded that impalement is dominated by depinning rather than sagging. With increasing velocity, the drops partially pin, and an increasing amount of liquid remains on the coating. A time-resolved study of the retraction dynamics reveals two well-separated phases: a fast inertia-dominated phase followed by a slow decrease of the contact diameter of the drop. The crossover occurs when the diameter of the retracting drop matches the diameter of the drop before impact. We suggest that the depth of impalement increases with impact velocity, where impalement is confined to the initial impact zone of the drop. If the drop partially pins on the coating, the depth of impalement exceeds a depth, preventing the whole drop from being removed during the retraction phase. PMID:23697383

  7. Fabrication of highly dense SiN4 ceramics without additives by high pressure sintering

    NASA Technical Reports Server (NTRS)

    Takatori, K.; Shimade, M.; Koizumi, M.

    1984-01-01

    Silicon nitride (Si3N4) is one of candidate materials for the engineering ceramics which is used at high temperatures. The mechanical strengths of hot pressed or sintered Si2N4 ceramics containing some amount of additives, however, are deteriorated at elevated temperatures. To improve the high temperature strength of Si3N4 ceramics, an attempt to consolidate Si3N4 without additives was made by high pressure sintering technique. Scanning electron micrographs of fracture surfaces of the sintered bodies showed the bodies had finely grained and fully self-bonded sintered bodies were 310N sq m at room temperature and 174N/sq m at 1200 C.

  8. Automated single cell sorting and deposition in submicroliter drops

    NASA Astrophysics Data System (ADS)

    Salánki, Rita; Gerecsei, Tamás; Orgovan, Norbert; Sándor, Noémi; Péter, Beatrix; Bajtay, Zsuzsa; Erdei, Anna; Horvath, Robert; Szabó, Bálint

    2014-08-01

    Automated manipulation and sorting of single cells are challenging, when intact cells are needed for further investigations, e.g., RNA or DNA sequencing. We applied a computer controlled micropipette on a microscope admitting 80 PCR (Polymerase Chain Reaction) tubes to be filled with single cells in a cycle. Due to the Laplace pressure, fluid starts to flow out from the micropipette only above a critical pressure preventing the precise control of drop volume in the submicroliter range. We found an anomalous pressure additive to the Laplace pressure that we attribute to the evaporation of the drop. We have overcome the problem of the critical dropping pressure with sequentially operated fast fluidic valves timed with a millisecond precision. Minimum drop volume was 0.4-0.7 μl with a sorting speed of 15-20 s per cell. After picking NE-4C neuroectodermal mouse stem cells and human primary monocytes from a standard plastic Petri dish we could gently deposit single cells inside tiny drops. 94 ± 3% and 54 ± 7% of the deposited drops contained single cells for NE-4C and monocytes, respectively. 7.5 ± 4% of the drops contained multiple cells in case of monocytes. Remaining drops were empty. Number of cells deposited in a drop could be documented by imaging the Petri dish before and after sorting. We tuned the adhesion force of cells to make the manipulation successful without the application of microstructures for trapping cells on the surface. We propose that our straightforward and flexible setup opens an avenue for single cell isolation, critically needed for the rapidly growing field of single cell biology.

  9. Pressure drop, heat transfer, critical heat flux, and flow stability of two-phase flow boiling of water and ethylene glycol/water mixtures - final report for project "Efficent cooling in engines with nucleate boiling."

    SciTech Connect

    Yu, W.; France, D. M.; Routbort, J. L.

    2011-01-19

    Because of its order-of-magnitude higher heat transfer rates, there is interest in using controllable two-phase nucleate boiling instead of conventional single-phase forced convection in vehicular cooling systems to remove ever increasing heat loads and to eliminate potential hot spots in engines. However, the fundamental understanding of flow boiling mechanisms of a 50/50 ethylene glycol/water mixture under engineering application conditions is still limited. In addition, it is impractical to precisely maintain the volume concentration ratio of the ethylene glycol/water mixture coolant at 50/50. Therefore, any investigation into engine coolant characteristics should include a range of volume concentration ratios around the nominal 50/50 mark. In this study, the forced convective boiling heat transfer of distilled water and ethylene glycol/water mixtures with volume concentration ratios of 40/60, 50/50, and 60/40 in a 2.98-mm-inner-diameter circular tube has been investigated in both the horizontal flow and the vertical flow. The two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux of the test fluids were determined experimentally over a range of the mass flux, the vapor mass quality, and the inlet subcooling through a new boiling data reduction procedure that allowed the analytical calculation of the fluid boiling temperatures along the experimental test section by applying the ideal mixture assumption and the equilibrium assumption along with Raoult's law. Based on the experimental data, predictive methods for the two-phase pressure drop, the forced convective boiling heat transfer coefficient, and the critical heat flux under engine application conditions were developed. The results summarized in this final project report provide the necessary information for designing and implementing nucleate-boiling vehicular cooling systems.

  10. Technology of eye drops containing aloe (Aloe arborescens Mill.--Liliaceae) and eye drops containing both aloe and neomycin sulphate.

    PubMed

    Kodym, A; Marcinkowski, A; Kukuła, H

    2003-01-01

    Eye drops made of aloe are a sterile, aqueous extract of fresh leaves of Aloe arborescens Mill., containing necessary additives and neomycin sulphate. The aim of the studies was to establish the technology of eye drops containing biologically active aloe substances and those containing both chemical constituents of aloe and neomycin sulphate. Within the studies, the formulary content and the way of preparing eye drops were determined, criteria were defined and methods of qualitative assessment of drops were proposed. On the basis of the proposed analytical methods, the physicochemical and microbiological stability of the eye drops stored at a temperature of 20-25 degrees C was studied. As the criteria of qualitative assessment of the eye drops, the following analyses were considered: sterility, appearance of the eye drops (clarity), pH, osmotic pressure, density, viscosity, TLC analysis, content of aloenin and aloin, studies of anti-microbial activity of neomycin in the drops, and preservative efficiency of thiomersal in the eye drops. The studies showed that the additives such as: sodium chloride, benzalkonium chloride, chlorhexidine diacetate and digluconate, phenylmercuric borate and Nipagins M and P could not be used to prepare the eye drops because they were involved in pharmaceutical interactions with chemical constituents of aloe in the eye drops. The eye drops containing: aqueous extract of fresh leaves of aloe, boric acid, thiomersal, sodium pyrosulphite, disodium EDTA, beta-phenylethyl alcohol and neomycin sulphate, both freshly prepared and after two years of storage, met the requirements of the Polish Pharmacopoeia (PPh V) mentioned in the monograph Guttae ophthalmicae. They were sterile, clear, their osmotic pressure approximated the osmotic pressure of lacrimal fluid and they were characterized by appropriate pH. Aloenin in the drops was much more stable than aloin. Neomycin after two years of storage retained almost 98% of its starting antimicrobial

  11. Inviscid Partial Coalescence from Bubbles to Drops

    NASA Astrophysics Data System (ADS)

    Zhang, F. H.; Taborek, P.; Burton, J.; Khoo, B. C.; Lim, K. M.; Thoroddsen, S. T.

    2010-11-01

    Coalescence of bubbles (drops) not only coarse the bubble (drop) sizes, but sometimes produces satellite bubbles (droplets), known as partial coalescence. To explore links between the drop and bubble cases, we experimentally study the partial coalescence of pressurized xenon gas bubbles in nano de-ionized water using high-speed video imaging. The size of these satellites relative to their mother bubbles is found to increase with the density ratio of the gas to the liquid. Moreover, sub-satellite bubbles are sometimes observed, whose size is also found to increase with the density ratio, while keeps about one quarter of the primary satellite. The time duration from start of the coalescence to formation of the satellites, scaled by the capillary time, increases with the density ratio too. In addition, as the size ratio of the father bubble to the mother bubble increases moderately, their coalescence proceeds faster and the sub-satellite is prone to form and relatively larger.

  12. A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: measurement principle and static calibration.

    PubMed

    Saccomandi, Paola; Schena, Emiliano; Silvestri, Sergio

    2011-02-01

    An optoelectronic target-type volumetric air flow-rate transducer for bidirectional measurements is presented. The sensor is composed of a T-shaped target and two nominally identical LED-photodiode couples which are operated in differential mode. The sensitive surfaces of the photodiodes are differentially shadowed by the deflection of the target, which in turn depends on the gas flow-rate. The principle of operation is described in mathematical terms and the design parameters have been optimized in order to obtain the highest sensitivity along with minimal pressure drop and reduced dimensions. The sensor is placed in a 20 mm diameter hose and was tested with air flow-rate in the typical temperature range of mechanical ventilation between 20 and 40 °C. The theoretical model was validated through experiments carried out in the volumetric flow range from -7.0 to +7.0 l min(-1). The nonlinear behavior allows sensitivities equal to 0.6 V l(-1) min for flow rates ranging from -2.0 to +2.0 l min(-1), equal to 2.0 V l(-1) min for flow rates ranging from -3.0 to -2.0 l min(-1) and from +2.0 to +3.0 l min(-1), up to 5.7 V l(-1) min at higher flow rates ranging from -7.0 to -3.0 l min(-1) and from +3.0 to +7.0 l min(-1). The linear range extends from 3.0 to 7.0 l min(-1) with constant sensitivity equal to 5.7 V l(-1) min. The sensor is able to detect a flow-rate equal to 1.0 l min(-1) with a sensitivity of about 400 mV l(-1) min. The differential nature of the output minimizes the influence of the LEDs' power supply variations and allows to obtain a repeatability in the order of 3% of full scale output. The small pressure drop produced by the sensor placed in-line the fluid stream, of about 2.4 Pa at 7 l min(-1), corresponds to a negligible fluid dynamic resistance lower than 0.34 Pa l(-1) min. PMID:21361616

  13. A novel target-type low pressure drop bidirectional optoelectronic air flow sensor for infant artificial ventilation: Measurement principle and static calibration

    NASA Astrophysics Data System (ADS)

    Saccomandi, Paola; Schena, Emiliano; Silvestri, Sergio

    2011-02-01

    An optoelectronic target-type volumetric air flow-rate transducer for bidirectional measurements is presented. The sensor is composed of a T-shaped target and two nominally identical LED-photodiode couples which are operated in differential mode. The sensitive surfaces of the photodiodes are differentially shadowed by the deflection of the target, which in turn depends on the gas flow-rate. The principle of operation is described in mathematical terms and the design parameters have been optimized in order to obtain the highest sensitivity along with minimal pressure drop and reduced dimensions. The sensor is placed in a 20 mm diameter hose and was tested with air flow-rate in the typical temperature range of mechanical ventilation between 20 and 40 °C. The theoretical model was validated through experiments carried out in the volumetric flow range from -7.0 to +7.0 l min-1. The nonlinear behavior allows sensitivities equal to 0.6 V l-1 min for flow rates ranging from -2.0 to +2.0 l min-1, equal to 2.0 V l-1 min for flow rates ranging from -3.0 to -2.0 l min-1 and from +2.0 to +3.0 l min-1, up to 5.7 V l-1 min at higher flow rates ranging from -7.0 to -3.0 l min-1 and from +3.0 to +7.0 l min-1. The linear range extends from 3.0 to 7.0 l min-1 with constant sensitivity equal to 5.7 V l-1 min. The sensor is able to detect a flow-rate equal to 1.0 l min-1 with a sensitivity of about 400 mV l-1 min. The differential nature of the output minimizes the influence of the LEDs' power supply variations and allows to obtain a repeatability in the order of 3% of full scale output. The small pressure drop produced by the sensor placed in-line the fluid stream, of about 2.4 Pa at 7 l min-1, corresponds to a negligible fluid dynamic resistance lower than 0.34 Pa l-1 min.

  14. Validated heat-transfer and pressure-drop prediction methods based on the discrete-element method: Phase 2, two-dimensional rib roughness

    SciTech Connect

    James, C.A.; Hodge, B.K.; Taylor, R.P.

    1993-05-01

    Surface roughness is a commonly used approach for enhancing the rate of heat transfer of surfaces, such as in heat-exchanger tubes. Because the improved thermal performance of roughened surfaces is at the expense of increased flow resistance (increased pressure drop or friction factor), accurate prediction techniques for determining the friction factors and Nusselt numbers for roughened surfaces are required if such features are to be considered as design options. This report presents the results of the second phase of a research program sponsored by Argonne National Laboratory to validate models for the prediction of friction factors and Nusselt numbers for fully developed turbulent flow in enhanced heat-exchanger tubes. The first phase was concerned with validating a roughness model for turbulent flow in tubes internally roughened with three-dimensional distributed roughness elements, such as sandgrains, spheres, hemispheres, and cones. The second phase is concerned with devising and validating methods for the prediction of friction factors and Nusselt numbers for turbulent flow in tubes internally roughened with repeated, two-dimensional ribs aligned perpendicular to the flow. The ribs are spaced sufficiently far apart that the leeward-side separated flow reattaches to the wall before again separating in order to negotiate the next rib. This heat-transfer enhancement mechanism is called the separation and reattachment mechanism, after Rabas (1989). This work is limited to rectangular rib shapes.

  15. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus minus} 6 MPa and a fracture toughness of 3.3 {plus minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  16. Influence of oxygen partial pressure and silver additions on microstructure and related properties of YBCO superconductors

    SciTech Connect

    Singh, J.P.; Joo, J.; Guttschow, R.; Poeppel, R.B.

    1992-02-01

    Microstructure has a great influence on the mechanical and superconducting properties of YBCO. Mechanical properties of YBCO can be improved by both modifying the monolithic microstructure and developing composites of YBCO with silver (Ag). When monolithic YBCO was sintered to high densities ({approx} 91%) at a relatively low temperature ({approx} 910{degrees}C) by controlling oxygen partial pressure during sintering, the result was a small-grain microstructure (average grain size {approx} 5 {mu}m) and hence a high strength of 191 {plus_minus} 7 MPa. Addition of Ag as a second phase further improved the strength of YBCO. Composites of YBCO with 10 to 15 vol % Ag has a strength of 225 {plus_minus} 6 MPa and a fracture toughness of 3.3 {plus_minus} 0.2 MPa{radical}m. These improvements are believed to be due to compressive stresses in the YBCO matrix as a result of thermal mismatch between the YBCO and Ag phases. Furthermore, the Ag particles may provide increased resistance to crack propagation by pinning the crack. On the other hand, addition of Ag as a dopant to substitute for Cu sites in YBCO has a profound but nonmonotonic effect on grain microstructure and the resulting critical current density.

  17. Glaucoma Surgery Calculator: Limited Additive Effect of Phacoemulsification on Intraocular Pressure in Ab Interno Trabeculectomy

    PubMed Central

    Schuman, Joel S.; Brown, Eric N.

    2016-01-01

    Purpose To compare intraocular pressure (IOP) reduction and to develop a predictive surgery calculator based on the results between trabectome-mediated ab interno trabeculectomy in pseudophakic patients versus phacoemulsification combined with trabectome-mediated ab interno trabeculectomy in phakic patients. Methods This observational surgical cohort study analyzed pseudophakic patients who received trabectome-mediated ab interno trabeculectomy (AIT) or phacoemulsification combined with AIT (phaco-AIT). Follow up for less than 12 months or neovascular glaucoma led to exclusion. Missing data was imputed by generating 5 similar but non-identical datasets. Groups were matched using Coarsened Exact Matching based on age, gender, type of glaucoma, race, preoperative number of glaucoma medications and baseline intraocular pressure (IOP). Linear regression was used to examine the outcome measures consisting of IOP and medications. Results Of 949 cases, 587 were included consisting of 235 AIT and 352 phaco-AIT. Baseline IOP between groups was statistically significant (p≤0.01) in linear regression models and was minimized after Coarsened Exact Matching. An increment of 1 mmHg in baseline IOP was associated with a 0.73±0.03 mmHg IOP reduction. Phaco-AIT had an IOP reduction that was only 0.73±0.32 mmHg greater than that of AIT. The resulting calculator to determine IOP reduction consisted of the formula -13.54+0.73 × (phacoemulsification yes:1, no:0) + 0.73 × (baseline IOP) + 0.59 × (secondary open angle glaucoma yes:1, no:0) + 0.03 × (age) + 0.09 × (medications). Conclusions This predictive calculator for minimally invasive glaucoma surgery can assist clinical decision making. Only a small additional IOP reduction was observed when phacoemulsification was added to AIT. Patients with a higher baseline IOP had a greater IOP reduction. PMID:27077914

  18. Drop Testing Representative Multi-Canister Overpacks

    SciTech Connect

    Snow, Spencer D.; Morton, Dana K.

    2015-06-01

    The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

  19. Additive Pressures of Elevated Sea Surface Temperatures and Herbicides on Symbiont-Bearing Foraminifera

    PubMed Central

    van Dam, Joost W.; Negri, Andrew P.; Mueller, Jochen F.; Altenburger, Rolf; Uthicke, Sven

    2012-01-01

    Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII) inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte) of benthic foraminifera in hospite. Diuron was shown to evoke a direct effect on photosynthetic efficiency (reduced effective PSII quantum yield ΔF/F′m), while elevated temperatures (>30°C, only 2°C above current average summer temperatures) were observed to impact photosynthesis more indirectly by causing reductions in maximum PSII quantum yield (Fv/Fm), interpreted as photodamage. Additionally, elevated temperatures were shown to cause bleaching through loss of chlorophyll a in foraminifera hosting either diatoms or dinoflagellates. A significant linear correlation was found between reduced Fv/Fm and loss of chlorophyll a. In most cases, symbionts within foraminifera proved more sensitive to thermal stress in the presence of diuron (≥1 µg L−1). The mixture toxicity model of Independent Action (IA) described the combined effects of temperature and diuron on the photosystem of species hosting diatoms or dinoflagellates convincingly and in agreement with probabilistic statistics, so a response additive joint action can be assumed. We thus demonstrate that improving water quality can improve resilience of symbiotic phototrophs to projected increases in ocean temperatures. As IA described the observed combined effects from elevated temperature and diuron stress it may therefore be employed for prediction of untested mixtures and for assessing the efficacy of management measures. PMID:22439012

  20. How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters.

    PubMed

    Leins, Martina; Gaiser, Sandra; Schulz, Andreas; Walker, Matthias; Schumacher, Uwe; Hirth, Thomas

    2015-01-01

    This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators - a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes. PMID:25938699

  1. Thermal behavior of water confined in micro porous of clay mineral at additional pressure.

    NASA Astrophysics Data System (ADS)

    Ito, Y.; Takemura, T.; Fujimori, H.; Nagoe, A.; Sugimoto, T.

    2014-12-01

    Water is the most familiar substance. However water has specific properties that has a crystal structure of a dozen and density of that is maximum at 277.15 K. Therefore it understands various natural phenomena to study physical properties of water. Oodo et al study physical properties of water confined in silica gel [1]. They indicate that melting point of water confined in silica gel decrease with decreasing pore size of silica gel. Also in case that pore size is less than 2 nm, water confined in silica gel is unfreezing water at low temperature. It is considered that effect of pore size prevent crystal growth of water. Therefore we are interested in water confined in clay minerals. Clay minerals have a number of water conditions. Also it is thought that water confined in clay minerals show different physical behavior to exist the domain where change with various effect. Therefore we studied a thermal properties and phase behavior of absorption water in clay minerals. In addition, we analyzed the changes in the thermal behavior of absorption water due to the effect of earth pressure that was an environmental factor in the ground. [1] Oodo & Fujimori, J. Non-Cryst. Solids, 357 (2011) 683.

  2. Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

    PubMed

    Schaper, J Niklas; Pfeuffer, Kevin P; Shelley, Jacob T; Bings, Nicolas H; Hieftje, Gary M

    2012-11-01

    One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 μg/mL, without sample pretreatment, were obtained. PMID:23025277

  3. Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid micro-volume samples

    PubMed Central

    Schaper, J. Niklas; Pfeuffer, Kevin P.; Shelley, Jacob T.; Bings, Nicolas H.

    2012-01-01

    One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed “drop-on-demand” (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (~17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 µg/mL, without sample pretreatment, were obtained. PMID:23025277

  4. 49 CFR 173.301b - Additional general requirements for shipment of UN pressure receptacles.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... match those of the valve outlets. (f) Hydrogen bearing gases. A steel UN pressure receptacle bearing an... of causing hydrogen embrittlement. (g) Composite cylinders in underwater use. A composite...

  5. 49 CFR 173.301b - Additional general requirements for shipment of UN pressure receptacles.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... match those of the valve outlets. (f) Hydrogen bearing gases. A steel UN pressure receptacle bearing an... of causing hydrogen embrittlement. (g) Composite cylinders in underwater use. A composite...

  6. Choking under Pressure: When an Additional Positive Stereotype Affects Performance for Domain Identified Male Mathematics Students

    ERIC Educational Resources Information Center

    Rosenthal, Harriet E. S.; Crisp, Richard J.

    2007-01-01

    This research aimed to establish if the presentation of two positive stereotypes would result in choking under pressure for identified male mathematics students. Seventy-five 16 year old men, who had just commenced their AS-level study, were either made aware of their gender group membership (single positive stereotype), their school group…

  7. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS...

  8. Exploding Water Drops

    NASA Astrophysics Data System (ADS)

    Reich, Gary

    2016-01-01

    Water has the unusual property that it expands on freezing, so that ice has a specific gravity of 0.92 compared to 1.0 for liquid water. The most familiar demonstration of this property is ice cubes floating in a glass of water. A more dramatic demonstration is the ice bomb shown in Fig. 1. Here a cast iron flask is filled with water and tightly stoppered. The flask is then cooled, either by leaving it outdoors in winter or by immersing it in a cryogenic fluid, until the water freezes. As the water freezes and expands, the pressure inside the flask increases dramatically, eventually becoming sufficient to fracture the metal walls of the enclosure. A related, but much less familiar, phenomenon is the explosive fracturing of small water drops upon freezing. That water drops can fracture in this way has been known for many years, and the phenomenon has been described in detail in the atmospheric sciences literature, where it is seen as relevant to the freezing of raindrops as they fall through cold air. Carefully controlled experiments have been done documenting how the character and frequency of fracture is affected by such variables as drop size, rate of cooling, chemistry of dissolved gases, etc. Here I describe instead a simple demonstration of fracture suitable for video analysis and appropriate for study at the introductory physics level. Readers may also be interested in other characteristics of freezing and fragmenting water drops, for example, charge separation upon fracture and the appearance of spikes and bulges on the surface.

  9. Clinoenstatite in alpe arami peridotite: additional evidence of very high pressure

    PubMed

    Bozhilov; Green; Dobrzhinetskaya

    1999-04-01

    Observations by transmission electron microscopy show that lamellae of clinoenstatite are present in diopside grains of the Alpe Arami garnet lherzolite of the Swiss Alps. The simplest interpretation of the orientation, crystallography, and microstructures of the lamellae and the phase relationships in this system is that the lamellae originally exsolved as the high-pressure C-centered form of clinoenstatite. These results imply that the rocks were exhumed from a minimum depth of 250 kilometers before or during continental collision. PMID:10102809

  10. Dilating Eye Drops

    MedlinePlus

    ... Frequently Asked Questions Español Condiciones Chinese Conditions Dilating Eye Drops En Español Read in Chinese What are dilating eye drops? Dilating eye drops contain medication to enlarge ( ...

  11. Hanging drop crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  12. Evaluation of the EHL Film Thickness and Extreme Pressure Additives on Gear Surface Fatigue Life

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis P.; Shimski, John

    1994-01-01

    Surface pitting fatigue life tests were conducted with seven lubricants, using AISI 9310 spur gears. The test lubricants can be classified as synthetic polyol-esters with various viscosities and additive packages. The lubricant with a viscosity that provided a specific film thickness greater than one and with an additive package produced gear surface fatigue lives that were 8.6 times that for lubricants with a viscosity that provided specific film thickness less than one. Lubricants with the same viscosity and similar additive packages gave equivalent gear surface fatigue lives.

  13. Effect of lubricant extreme pressure additives on rolling element fatigue life

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1973-01-01

    The effects of surface active additives on rolling-element fatigue life were investigated with the five-ball fatigue tester at conditions where classical subsurface initiated rolling-element fatigue is the sole mode of failure. Test balls of AISI 52100, AISI M-50, and AISI 1018 were run with an acid-treated white oil containing either 2.5 percent sulfurized terpene, 1 percent didodecyl phosphite, or 5 percent chlorinated wax. In general, it was found that the influence of surface active additives was detrimental to rolling-element fatigue life. The chlorinated-wax additive significantly reduced fatigue life by a factor of 7. The base oil with the 2.5 percent sulfurized-terpene additive can reduce fatigue life by as much as 50 percent. No statistical change in fatigue life occurred with the base oil having the 1 percent didodecyl-phosphite additive. The additives used with the base oil did not change the ranking of the bearing steels where rolling-element fatigue life was of subsurface origin.

  14. Central hemodynamics in risk assessment strategies: additive value over and above brachial blood pressure.

    PubMed

    Yannoutsos, Alexandra; Rinaldi, Elisa R; Zhang, Yi; Protogerou, Athanassios D; Safar, Michel E; Blacher, Jacques

    2015-01-01

    Although the clinical relevance of brachial blood pressure (BP) measurement for cardiovascular (CV) risk stratification is nowadays widely accepted, this approach can nevertheless present several limitations. Pulse pressure (PP) amplification accounts for the notable increase in PP from central to peripheral arterial sites. Target organs are more greatly exposed to central hemodynamic changes than peripheral organs. The pathophysiological significance of local BP pulsatility, which has a role in the pathogenesis of target organ damage in both the macro- and the microcirculation, may therefore not be accurately captured by brachial BP as traditionally evaluated with cuff measurements. The predictive value of central systolic BP and PP over brachial BP for major clinical outcomes has been demonstrated in the general population, in elderly adults and in patients at high CV risk, irrespective of the invasive or non-invasive methods used to assess central BP. Aortic stiffness, timing and intensity of wave reflections, and cardiac performance appear as major factors influencing central PP. Great emphasis has been placed on the role of aortic stiffness, disturbed arterial wave reflections and their intercorrelation in the pathophysiological mechanisms of CV diseases as well as on their capacity to predict target organ damage and clinical events. Comorbidities and age-related changes, together with gender-related specificities of arterial and cardiac parameters, are known to affect the predictive ability of central hemodynamics on individual CV risk. PMID:25341861

  15. Effect of lubricant extreme-pressure additives on surface fatigue life of AISI 9310 spur gears

    NASA Technical Reports Server (NTRS)

    Scibbe, H. W.; Townsend, D. P.; Aron, P. R.

    1984-01-01

    Surface fatigue tests were conducted with AISI 9310 spur gears using a formulated synthetic tetraester oil (conforming to MIL-L-23699 specifications) as the lubricant containing either sulfur or phosphorus as the EP additive. Four groups of gears were tested. One group of gears tested without an additive in the lubricant acted as the reference oil. In the other three groups either a 0.1 wt % sulfur or phosphorus additive was added to the tetraester oil to enhance gear surface fatigue life. Test conditions included a gear temperature of 334 K (160 F), a maximum Hertz stress of 1.71 GPa (248 000 psi), and a speed of 10,000 rpm. The gears tested with a 0.1 wt % phosphorus additive showed pitting fatigue life 2.6 times the life of gears tested with the reference tetraester based oil. Although fatigue lives of two groups of gears tested with the sulfur additive in the oil showed improvement over the control group gear life, the results, unlike those obtained with the phosphorus oil, were not considered to be statistically significant.

  16. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet.

    PubMed

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T H; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  17. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-10-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

  18. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    PubMed Central

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  19. Effects of reduced pressure and additives on streamers in white oil in long point-plane gap

    NASA Astrophysics Data System (ADS)

    Dung, N. V.; Høidalen, H. K.; Linhjell, D.; Lundgaard, L. E.; Unge, M.

    2013-06-01

    Recent experiments show that modern dielectric liquids behave differently from traditional mineral oil, particularly with respect to breakdown voltages for lightning impulse. This paper describes an experimental investigation addressing underlying reasons for this. The influences of reduced pressure and additives on streamers in white oil were investigated under both positive and negative polarities using an 8 cm long point-plane gap. Reduced pressure significantly accelerates streamers, thus increasing stopping length and reducing both breakdown and acceleration voltages. With increasing applied voltage, different typical propagation modes of streamers were recorded for both polarities. A low ionization potential additive strongly affects positive streamers. It significantly changes streamer velocity and reduces the breakdown voltage but increases the acceleration voltage where breakdown streamer velocity increases drastically. Adding an electron scavenger influences streamers of both polarities, but it mainly increases the velocity of negative streamers and results in a reduction of both the breakdown and the acceleration voltages. The propagation mechanisms of streamers are also discussed.

  20. EVAPORATION: a new vapor pressure estimation method for organic molecules including non-additivity and intramolecular interactions

    NASA Astrophysics Data System (ADS)

    Compernolle, S.; Ceulemans, K.; Müller, J.-F.

    2011-04-01

    We present EVAPORATION (Estimation of VApour Pressure of ORganics, Accounting for Temperature, Intramolecular, and Non-additivity effects), a method to predict vapour pressure p0 of organic molecules needing only molecular structure as input. The method is applicable to zero-, mono- and polyfunctional molecules. A simple formula to describe log10p0(T) is employed, that takes into account both a wide temperature dependence and the non-additivity of functional groups. In order to match the recent data on functionalised diacids an empirical modification to the method was introduced. Contributions due to carbon skeleton, functional groups, and intramolecular interaction between groups are included. Molecules typically originating from oxidation of biogenic molecules are within the scope of this method: carbonyls, alcohols, ethers, esters, nitrates, acids, peroxides, hydroperoxides, peroxy acyl nitrates and peracids. Therefore the method is especially suited to describe compounds forming secondary organic aerosol (SOA).

  1. Static Magnetowetting of Ferrofluid Drops.

    PubMed

    Rigoni, Carlo; Pierno, Matteo; Mistura, Giampaolo; Talbot, Delphine; Massart, René; Bacri, Jean-Claude; Abou-Hassan, Ali

    2016-08-01

    We report results of a comprehensive study of the wetting properties of sessile drops of ferrofluid water solutions at various concentrations deposited on flat substrates and subjected to the action of permanent magnets of different sizes and strengths. The amplitude and the gradient of the magnetic field experienced by the ferrofluid are changed by varying the magnets and their distance to the surface. Magnetic forces up to 100 times the gravitational one and magnetic gradients up to 1 T/cm are achieved. A rich phenomenology is observed, ranging from flattened drops caused by the magnetic attraction to drops extended normally to the substrate because of the normal traction of the magnetic field. We find that the former effect can be conveniently described in terms of an effective Bond number that compares the effective drop attraction with the capillary force, whereas the drop's vertical elongation is effectively expressed by a dimensionless number S, which compares the pressure jump at the ferrofluid interface because of the magnetization with the capillary pressure. PMID:27385506

  2. Drop tests of the Three Mile Island knockout canister

    SciTech Connect

    Box, W.D.; Aaron, W.S.; Shappert, L.B.; Childress, P.C.; Quinn, G.J.; Smith, J.V.

    1986-09-01

    A type of Three Mile Island Unit 2 (TMI-2) defueling canister, called a ''knockout'' canister, was subjected to a series of drop tests at the Oak Ridge National Laboratory's Drop Test Facility. These tests were designed to confirm the structural integrity of internal fixed neutron poisons in support of a request for NRC licensing of this type of canister for the shipment of TMI-2 reactor fuel debris to the Idaho National Engineering Laboratory (INEL) for the Core Examination R and D Program. Work conducted at the Oak Ridge National Laboratory included (1) precise physical measurements of the internal poison rod configuration before assembly, (2) canister assembly and welding, (3) nondestructive examination (an initial hydrostatic pressure test and an x-ray profile of the internals before and after each drop test), (4) addition of a simulated fuel load, (5) instrumentation of the canister for each drop test, (6) fabrication of a cask simulation vessel with a developed and tested foam impact limiter, (7) use of refrigeration facilities to cool the canister to well below freezing prior to three of the drops, (8) recording the drop test with still, high-speed, and normal-speed photography, (9) recording the accelerometer measurements during impact, (10) disassembly and post-test examination with precise physical measurements, and (11) preparation of the final report.

  3. Equilibrium shapes of acoustically levitated drops

    NASA Astrophysics Data System (ADS)

    Trinh, E. H.; Hsu, C.-J.

    1986-05-01

    The quantitative determination of the shape of liquid drops levitated in an ultrasonic standing wave has provided experimental data on the radiation pressure-induced deformations of freely suspended liquids. Within the limits of small deviations from the spherical shape and small drop diameter relative to the acoustic wavelength, an existing approximate theory yields a good agreement with experimental evidence. The data were obtained for millimeter and submillimeter drops levitated in air under 1 g, where g is the sea level gravitational acceleration.

  4. Alternate drop pulse polarography

    USGS Publications Warehouse

    Christie, J.H.; Jackson, L.L.; Osteryoung, R.A.

    1976-01-01

    The new technique of alternate drop pulse polarography is presented. An experimental evaluation of alternate drop pulse polarography shows complete compensation of the capacitative background due to drop expansion. The capillary response phenomenon was studied in the absence of faradaic reaction and the capillary response current was found to depend on the pulse width to the -0.72 power. Increased signal-to-noise ratios were obtained using alternate drop pulse polarography at shorter drop times.

  5. Comparison of Predicted and Experimental Heat-Transfer and Pressure-Drop Results for an Air-Cooled Plug Nozzle and Supporting Struts

    NASA Technical Reports Server (NTRS)

    Graber, E. J., Jr.; Clark, J. S.

    1972-01-01

    A calculational procedure is presented to analyze the heat-transfer and fluid-flow characteristics of a convectively air -cooled plug-nozzle operating on an afterburning turbojet engine. Anderson's method was used to predict hot-gas static pressures in the supersonic stream with fully expanded flow (high nozzle-pressure ratios); the results were excellent. For low nozzle-pressure ratios, the flow was assumed to expand one-dimensionally and isentropically to the plug back pressure. Wall temperatures predicted using this latter pressure distribution agreed well with the wall temperatures predicted using the measured hot-gas pressures (maximum deviation was about 30 K (54 deg R)). Either an in tegral boundary-layer technique or a simple pipe-flow equation may be used to calculate convective heat transfer from the hot gas to the wall. The simple pipeflow equation results in the prediction of slightly higher wall temperatures than does the integral technique. Experimental wall temperatures were generally in good agreement with the two predicted wall temperature distributions. Excellent agreement was noted b etween measured and predicted coolant static-pressure distributions. The plug-coolant temperature rise was generally overpredicted by about 22.2 K (40 deg R); possible explanations are offered. Although an an alysis of the struts, which support the plug, was purposely kept simple, reasonable results were obtained. Potential flow over an ellipse was used to calculate hot-gas static pressure; the results were satisfactory.

  6. Injector Element which Maintains a Constant Mean Spray Angle and Optimum Pressure Drop During Throttling by Varying the Geometry of Tangential Inlets

    NASA Technical Reports Server (NTRS)

    Trinh, Huu P. (Inventor); Myers, William Neill (Inventor)

    2014-01-01

    A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The tangential inlet area for each throttleable stage is calculated. The correlation between the tangential inlet areas and delta pressure values is used to calculate the spring displacement and variable inlet geometry. An injector designed using the method includes a plurality of geometrically calculated tangential inlets in an injection tube; an injection tube cap with a plurality of inlet slots slidably engages the injection tube. A pressure differential across the injector element causes the cap to slide along the injection tube and variably align the inlet slots with the tangential inlets.

  7. Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

    2008-01-01

    Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

  8. Electrohydrodynamics of a viscous drop with inertia.

    PubMed

    Nganguia, H; Young, Y-N; Layton, A T; Lai, M-C; Hu, W-F

    2016-05-01

    Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number Ca_{E}. Below the critical Ca_{E}, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed Ca_{E}, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical Ca_{E}, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations. PMID:27300985

  9. Electrohydrodynamics of a viscous drop with inertia

    NASA Astrophysics Data System (ADS)

    Nganguia, H.; Young, Y.-N.; Layton, A. T.; Lai, M.-C.; Hu, W.-F.

    2016-05-01

    Most of the existing numerical and theoretical investigations on the electrohydrodynamics of a viscous drop have focused on the creeping Stokes flow regime, where nonlinear inertia effects are neglected. In this work we study the inertia effects on the electrodeformation of a viscous drop under a DC electric field using a novel second-order immersed interface method. The inertia effects are quantified by the Ohnesorge number Oh, and the electric field is characterized by an electric capillary number CaE. Below the critical CaE, small to moderate electric field strength gives rise to steady equilibrium drop shapes. We found that, at a fixed CaE, inertia effects induce larger deformation for an oblate drop than a prolate drop, consistent with previous results in the literature. Moreover, our simulations results indicate that inertia effects on the equilibrium drop deformation are dictated by the direction of normal electric stress on the drop interface: Larger drop deformation is found when the normal electric stress points outward, and smaller drop deformation is found otherwise. To our knowledge, such inertia effects on the equilibrium drop deformation has not been reported in the literature. Above the critical CaE, no steady equilibrium drop deformation can be found, and often the drop breaks up into a number of daughter droplets. In particular, our Navier-Stokes simulations show that, for the parameters we use, (1) daughter droplets are larger in the presence of inertia, (2) the drop deformation evolves more rapidly compared to creeping flow, and (3) complex distribution of electric stresses for drops with inertia effects. Our results suggest that normal electric pressure may be a useful tool in predicting drop pinch-off in oblate deformations.

  10. Deformation and secondary breakup of drops

    NASA Astrophysics Data System (ADS)

    Hsiang, L.-P.; Faeth, G. M.

    1993-01-01

    Drop properties during and after secondary breakup in the bag, multimode and shear breakup regimes were observed for shock wave initiated disturbances in air at normal temperature and pressure. Test liquids included water, n-heptane, ethyl alcohol and glycerol mixtures to yield Weber numbers of 15-600. Ohnesorge numbers of 0.0025-0.039, liquid/gas density ratios of 579-985 and Reynolds numbers of 1060-15080. Measurements included pulsed shadowgraphy and double-pulsed holography to find drop sizes and velocities after breakup. Drop size distributions after breakup satisfied Simmons' universal root normal distribution in all three breakup regimes, after removing the core (or drop-forming) drop from the drop population for shear breakup. The size and velocity of the core drop after shear breakup then was correlated successfully based on the observation that the end of drop stripping corresponded to a constant Eotvos number. The relative velocities of the drop liquid were significantly reduced during secondary breakup, due both to large drag coefficients during the drop deformation stage and reduced relaxation times of smaller drops. These effects were correlated successfully based on a simplified phenomenological theory.

  11. Longitudinal Slit Procedure in Addition to Negative Pressure Wound Therapy for a Refractory Wound With Exposed Achilles Tendon

    PubMed Central

    Ohata, Erika; Mishima, Yoshito; Matsuo, Kiyoshi

    2015-01-01

    Objective: This case report reviews features of negative pressure wound therapy, particularly for the exposed Achilles tendon, and describes an additional effective procedure. Methods: An 87-year-old man presented with a soft-tissue defect measuring 3×5 cm with the exposed Achilles tendon as a sequela of deep burn. The condition of his affected leg was ischemic because of arteriosclerosis. We used negative pressure wound therapy and made 2 longitudinal slits penetrating the tendon to induce blood flow from the ventral side to the dorsal surface. Results: By this combination therapy, the surface of the exposed Achilles tendon was completely epithelialized and the tendon was spared without disuse syndrome. Conclusions: The authors conclude that this combination therapy is useful for covering the widely exposed tendon in aged patients. PMID:25848445

  12. Nonlinear oscillations of inviscid free drops

    NASA Technical Reports Server (NTRS)

    Patzek, T. W.; Benner, R. E., Jr.; Basaran, O. A.; Scriven, L. E.

    1991-01-01

    The present analysis of free liquid drops' inviscid oscillations proceeds through solution of Bernoulli's equation to obtain the free surface shape and of Laplace's equation for the velocity potential field. Results thus obtained encompass drop-shape sequences, pressure distributions, particle paths, and the temporal evolution of kinetic and surface energies; accuracy is verified by the near-constant drop volume and total energy, as well as the diminutiveness of mass and momentum fluxes across drop surfaces. Further insight into the nature of oscillations is provided by Fourier power spectrum analyses of mode interactions and frequency shifts.

  13. Instabilities of volatile films and drops

    NASA Astrophysics Data System (ADS)

    Murisic, Nebojsa

    2008-12-01

    We report on instabilities during spreading of volatile liquids, with emphasis on the novel instability observed when isopropyl alcohol (IPA) is deposited on a monocrystalline silicon (Si) wafer. This instability is characterized by emission of drops ahead of the expanding front, with each drop followed by smaller, satellite droplets, forming the structures which we nickname "octopi" due to their appearance. A less volatile liquid, or a substrate of larger heat conductivity, suppress this instability. In addition, we examine the spreading of drops of water (DIW)-IPA mixtures on both Si wafers and plain glass slides, and describe the variety of contact line instabilities which appear. We find that the decrease of IPA concentration in mixtures leads to transition from "octopi" to mushroom-like instabilities. Through manipulation of our experimental set up, we also find that the mechanism responsible for these instabilities appears to be mostly insensitive to both the external application of convection to the gas phase, and the doping of the gas phase with vapor in order to create the saturated environment. In order to better understand the "octopi" instability, we develop a theoretical model for evaporation of a pure liquid drop on a thermally conductive solid substrate. This model includes all relevant physical effects, including evaporation, thermal conductivity in both liquid and solid, (thermocapillary) Marangoni effect, vapor recoil, disjoining pressure, and gravity. The crucial ingredient in this problem is the evaporation model, since it influences both the motion of the drop contact line, and the temperature profiles along the liquid-solid and liquid-gas interfaces. We consider two evaporation models: the equilibrium "lens" model and the non-equilibrium one-sided (NEOS) model. Along with the assumption of equilibrium at the liquid-gas interface, the "lens" model also assumes that evaporation proceeds in a (vapor) diffusion-limited regime, therefore bringing

  14. Attracting Water Drops

    NASA Video Gallery

    Astronauts Cady Coleman and Ron Garan perform the Attracting Water Drops experiment from Chabad Hebrew Academy in San Diego, Calif. This research determines if a free-floating water drop can be att...

  15. Dilating Eye Drops

    MedlinePlus

    ... Conditions Most Common Searches Adult Strabismus Amblyopia Cataract Conjunctivitis Corneal Abrasions Dilating Eye Drops Lazy eye (defined) ... Loading... Most Common Searches Adult Strabismus Amblyopia Cataract Conjunctivitis Corneal Abrasions Dilating Eye Drops Lazy eye (defined) ...

  16. Ternary drop collisions

    NASA Astrophysics Data System (ADS)

    Hinterbichler, Hannes; Planchette, Carole; Brenn, Günter

    2015-10-01

    It has been recently proposed to use drop collisions for producing advanced particles or well-defined capsules, or to perform chemical reactions where the merged drops constitute a micro-reactor. For all these promising applications, it is essential to determine whether the merged drops remain stable after the collision, forming a single entity, or if they break up. This topic, widely investigated for binary drop collisions of miscible and immiscible liquid, is quite unexplored for ternary drop collisions. The current study aims to close this gap by experimentally investigating collisions between three equal-sized drops of the same liquid arranged centri-symmetrically. Three drop generators are simultaneously operated to obtain controlled ternary drop collisions. The collision outcomes are observed via photographs and compared to those of binary collisions. Similar to binary collisions, a regime map is built, showing coalescence and bouncing as well as reflexive and stretching separation. Significant differences are observed in the transitions between these regimes.

  17. Design and analysis of a piezoelectric material based touch screen with additional pressure and its acceleration measurement functions

    NASA Astrophysics Data System (ADS)

    Chu, Xiang-Cheng; Liu, Jia-Yi; Gao, Ren-Long; Chang, Jie; Li, Long-Tu

    2013-12-01

    Touch screens are becoming more and more prevalent in everyday environments due to their convenience and humanized operation. In this paper, a piezoelectric material based touch screen is developed and investigated. Piezoelectric ceramics arrayed under the touch panel at the edges or corners are used as tactile sensors to measure the touch positioning point similarly to conventional touch screens. However, additional touch pressure and its acceleration performance can also be obtained to obtain a higher-level human-machine interface. The piezoelectric ceramics can also be added to a traditional touch screen structure, or they can be used independently to construct a novel touch screen with a high light transmittance approach to a transparent glass. The piezoelectric ceramics were processed from PZT piezoelectric ceramic powder into a round or rectangular shape. According to the varied touch position and physical press strength of a finger, or even a gloved hand or fingernail, the piezoelectric tactile sensors will have different output voltage responses. By calculating the ratio of different piezoelectric tactile sensors’ responses and summing up all piezoelectric tactile sensors’ output voltages, the touch point position, touch pressure and touch force acceleration can be detected. A prototype of such a touch screen is manufactured and its position accuracy, touch pressure and response speed are measured in detail. The experimental results show that the prototype has many advantages such as high light transmittance, low energy cost and high durability.

  18. The role of the anchoring conditions in the electro rheological behavior of a nematic constrained by two coaxial cylinders and submitted by a pressure drop

    NASA Astrophysics Data System (ADS)

    Martínez Sánchez, Daniel; Reyes Cervantes, Juan Adrián

    We study a nematic liquid crystal (LC) filling the region between two coaxial cylinders subjected to the simultaneous action of both a pressure gradient applied parallel to the axis of the cylinders and a radial low frequency electric field. For the LC 4'-n-pentyl-4-cyanobiphenyl (5CB), we consider soft anchoring boundary conditions to obtain the configuration of the director and the velocity profile and the pressure gradient for nonslip boundary conditions. Finally, we calculate the effective viscosity, the first normal stress difference, and the dragging forces on the cylinders.

  19. Modulation of the interbilayer hydration pressure by the addition of dipoles at the hydrocarbon/water interface.

    PubMed Central

    Simon, S A; McIntosh, T J; Magid, A D; Needham, D

    1992-01-01

    The effects of the cholesterol analog 5 alpha-cholestan-3 beta-ol-6-one (6-ketocholestanol) on bilayer structure, bilayer cohesive properties, and interbilayer repulsive pressures have been studied by a combination of x-ray diffraction, pipette aspiration, and dipole potential experiments. It is found that 6-ketocholestanol, which has a similar structure to cholesterol except with a keto moiety at the 6 position of the B ring, has quite different effects than cholesterol on bilayer organization and cohesive properties. Unlike cholesterol, 6-ketocholestanol does not appreciably modify the thickness of liquid-crystalline egg phosphatidylcholine (EPC) bilayers, and causes a much smaller increase in bilayer compressibility modulus than does cholesterol. These data imply that 6-ketocholestanol has both its hydroxyl and keto moieties situated near the water-hydrocarbon interface, thus making its orientation in the bilayer different from cholesterol's. The addition of equimolar 6-ketocholestanol into EPC bilayers increases the magnitude, but not the decay length, of the exponentially decaying repulsive hydration pressure between adjacent bilayers. Incorporation of equimolar 6-ketocholestanol into EPC monolayers increases the dipole potential by approximately 300 mV. These data are consistent with our previous observation that the magnitude of the hydration pressure is proportional to the square of the dipole potential. These results mean that 6-ketocholestanol, despite its location in the bilayer hydrocarbon region, approximately 10 A from the physical edge of the bilayer, modifies the organization of interlamellar water. We argue that the incorporation of 6-ketocholestanol into EPC bilayers increases the hydration pressure, at least in part, by increasing the electric field strength in the polar head group region. PMID:1504249

  20. Green technology effect of injection pressure, timing and compression ratio in constant pressure heat addition cycle by an eco-friendly material.

    PubMed

    Karthikayan, S; Sankaranarayanan, G; Karthikeyan, R

    2015-11-01

    Present energy strategies focus on environmental issues, especially environmental pollution prevention and control by eco-friendly green technologies. This includes, increase in the energy supplies, encouraging cleaner and more efficient energy management, addressing air pollution, greenhouse effect, global warming, and climate change. Biofuels provide the panorama of new fiscal opportunities for people in rural area for meeting their need and also the demand of the local market. Biofuels concern protection of the environment and job creation. Renewable energy sources are self-reliance resources, have the potential in energy management with less emissions of air pollutants. Biofuels are expected to reduce dependability on imported crude oil with connected economic susceptibility, reduce greenhouse gases, other pollutants and invigorate the economy by increasing demand and prices for agricultural products. The use of neat paradise tree oil and induction of eco-friendly material Hydrogen through inlet manifold in a constant pressure heat addition cycle engine (diesel engine) with optimized engine operating parameters such as injection timing, injection pressure and compression ratio. The results shows the heat utilization efficiency for neat vegetable oil is 29% and neat oil with 15% Hydrogen as 33%. The exhaust gas temperature (EGT) for 15% of H2 share as 450°C at full load and the heat release of 80J/deg. crank angle for 15% Hydrogen energy share. PMID:26025643

  1. The cryogenic bonding evaluation at the metallic-composite interface of a composite overwrapped pressure vessel with additional impact investigation

    NASA Astrophysics Data System (ADS)

    Clark, Eric A.

    A bonding evaluation that investigated the cryogenic tensile strength of several different adhesives/resins was performed. The test materials consisted of 606 aluminum test pieces adhered to a wet-wound graphite laminate in order to simulate the bond created at the liner-composite interface of an aluminum-lined composite overwrapped pressure vessel. It was found that for cryogenic applications, a flexible, low modulus resin system must be used. Additionally, the samples prepared with a thin layer of cured resin -- or prebond -- performed significantly better than those without. It was found that it is critical that the prebond surface must have sufficient surface roughness prior to the bonding application. Also, the aluminum test pieces that were prepared using a surface etchant slightly outperformed those that were prepared with a grit blast surface finish and performed significantly better than those that had been scored using sand paper to achieve the desired surface finish. An additional impact investigation studied the post impact tensile strength of composite rings in a cryogenic environment. The composite rings were filament wound with several combinations of graphite and aramid fibers and were prepared with different resin systems. The rings were subjected to varying levels of Charpy impact damage and then pulled to failure in tension. It was found that the addition of elastic aramid fibers with the carbon fibers mitigates the overall impact damage and drastically improves the post-impact strength of the structure in a cryogenic environment.

  2. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    PubMed Central

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  3. Investigating the effect of additional gases in an atmospheric-pressure helium plasma jet using ambient mass spectrometry

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Furuta, Hiroshi; Hatta, Akimitsu; Bradley, James W.

    2015-01-01

    Using ambient mass spectrometry, positive and negative ions created in an atmospheric-pressure plasma jet have been detected for a variation of different traces gases (Ar, N2, and O2) added to the flow, downstream of the main helium discharge plasma. We find that such additions can change the chemistry in the outflow plasma plume. For instance, small amounts of O2 increases the formation of positive ion clusters, e.g., water clusters H+(H2O)n (with n up to 5) through hydration reactions, but decreases the intensity of heavy negative ions detected. With the addition of Ar and N2 we see a marked decrease in the intensity of negative ions in the plume but with increased Ar+ and nitrous oxide ions (e.g., N2O+) for the two cases respectively. From broadband optical emission measurements of the glowing plasma we see that the relative emission intensity of OH radical were changed with addition of the four different gases but the emission spectra were not changed. A calculation of rotational temperature of OH radicals, indicates that the gas temperatures is about 290 K for the four different gas mixture cases.

  4. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives.

    PubMed

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-01-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application. PMID:26951794

  5. Layered Double Hydroxide Nanoplatelets with Excellent Tribological Properties under High Contact Pressure as Water-Based Lubricant Additives

    NASA Astrophysics Data System (ADS)

    Wang, Hongdong; Liu, Yuhong; Chen, Zhe; Wu, Bibo; Xu, Sailong; Luo, Jianbin

    2016-03-01

    High efficient and sustainable utilization of water-based lubricant is essential for saving energy. In this paper, a kind of layered double hydroxide (LDH) nanoplatelets is synthesized and well dispersed in water due to the surface modification with oleylamine. The excellent tribological properties of the oleylamine-modified Ni-Al LDH (NiAl-LDH/OAm) nanoplatelets as water-based lubricant additives are evaluated by the tribological tests in an aqueous environment. The modified LDH nanoplatelets are found to not only reduce the friction but also enhance the wear resistance, compared with the water-based cutting fluid and lubricants containing other particle additives. By adding 0.5 wt% LDH nanoplatelets, under 1.5 GPa initial contact pressure, the friction coefficient, scar diameter, depth and width of the wear track dramatically decrease by 83.1%, 43.2%, 88.5% and 59.5%, respectively. It is considered that the sufficiently small size and the excellent dispersion of NiAl-LDH/OAm nanoplatelets in water are the key factors, so as to make them enter the contact area, form a lubricating film and prevent direct collision of asperity peaks. Our investigations demonstrate that the LDH nanoplatelet as a water-based lubricant additive has a great potential value in industrial application.

  6. Comparison of the anti-inflammatory activity and effect on intraocular pressure of fluoromethalone, clobetasone butyrate and betamethasone phosphate eye drops.

    PubMed

    Kadom, A H; Forrester, J V; Williamson, T H

    1986-01-01

    The effect of fluoromethalone 0.1% suspension (FML), clobetasone butyrate 0.1% (Eumovate) and betamethasone phosphate 0.1% (Betnesol) in post-operative inflammation was studied in 60 eyes (50 patients) in a randomized trial. No significant differences were noted, although two patients required higher penetration steroids than FML or Eumovate. Betnesol seemed to have a greater tendency to cause raised intraocular pressure than FML. In this series, however, the authors are unable to comment on differences between Eumovate and Betnesol. PMID:3547254

  7. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... than the vapor pressure of the liquid at 65 °C. (3) For high pressure liquefied gases or gas mixtures... compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations... pressure receptacles. (a) General. Liquefied gases and gas mixtures must be offered for transportation...

  8. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... than the vapor pressure of the liquid at 65 °C. (3) For high pressure liquefied gases or gas mixtures... compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations... pressure receptacles. (a) General. Liquefied gases and gas mixtures must be offered for transportation...

  9. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... than the vapor pressure of the liquid at 65 °C. (3) For high pressure liquefied gases or gas mixtures... compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations... pressure receptacles. (a) General. Liquefied gases and gas mixtures must be offered for transportation...

  10. 49 CFR 173.304b - Additional requirements for shipment of liquefied compressed gases in UN pressure receptacles.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... than the vapor pressure of the liquid at 65 °C. (3) For high pressure liquefied gases or gas mixtures... compressed gases in UN pressure receptacles. 173.304b Section 173.304b Transportation Other Regulations... pressure receptacles. (a) General. Liquefied gases and gas mixtures must be offered for transportation...

  11. Sintered-reaction Bonded Silicon Nitride Densified by a Gas Pressure Sintering Process Effects of Rare Earth Oxide Sintering Additives

    SciTech Connect

    Lee, S. H.; Ko, J. W.; Park, Y. J.; Kim, H. D.; Lin, Hua-Tay; Becher, Paul F

    2012-01-01

    Reaction-bonded silicon nitrides containing rare-earth oxide sintering additives were densified by gas pressure sintering. The sintering behavior, microstructure and mechanical properties of the resultant specimens were analyzed. For that purpose, Lu2O3-SiO2 (US), La2O3-MgO (AM) and Y2O3-Al2O3 (YA) additive systems were selected. Among the tested compositions, densification of silicon nitride occurred at the lowest temperature when using the La2O3-MgO system. Since the Lu2O3-SiO2 system has the highest melting temperature, full densification could not be achieved after sintering at 1950oC. However, the system had a reasonably high bending strength of 527 MPa at 1200oC in air and a high fracture toughness of 9.2 MPa m1/2. The Y2O3-Al2O3 system had the highest room temperature bending strength of 1.2 GPa

  12. Drag on Sessile Drops

    NASA Astrophysics Data System (ADS)

    Milne, Andrew J. B.; Fleck, Brian; Nobes, David; Sen, Debjyoti; Amirfazli, Alidad; University of Alberta Mechanical Engineering Collaboration

    2013-11-01

    We present the first ever direct measurements of the coefficient of drag on sessile drops at Reynolds numbers from the creeping flow regime up to the point of incipient motion, made using a newly developed floating element differential drag sensor. Surfaces of different wettabilities (PMMA, Teflon, and a superhydrophobic surface (SHS)), wet by water, hexadecane, and various silicone oils, are used to study the effects of drop shape, and fluid properties on drag. The relation between drag coefficient and Reynolds number (scaled by drop height) varies slightly with liquid-solid system and drop volume with results suggesting the drop experiences increased drag compared to similar shaped solid bodies due to drop oscillation influencing the otherwise laminar flow. Drops adopting more spherical shapes are seen to experience the greatest force at any given airspeed. This indicates that the relative exposed areas of drops is an important consideration in terms of force, with implications for the shedding of drops in applications such as airfoil icing and fuel cell flooding. The measurement technique used in this work can be adapted to measure drag force on other deformable, lightly adhered objects such as dust, sand, snow, vesicles, foams, and biofilms. The authours acknowledge NSERC, Alberta Innovates Technology Futures, and the Killam Trusts.

  13. Surfactant and nonlinear drop dynamics in microgravity

    NASA Astrophysics Data System (ADS)

    Jankovsky, Joseph Charles

    2000-11-01

    Large amplitude drop dynamics in microgravity were conducted during the second United States Microgravity Laboratory mission carried onboard the Space Shuttle Columbia (20 October-5 November 1995). Centimeter- sized drops were statically deformed by acoustic radiation pressure and released to oscillate freely about a spherical equilibrium. Initial aspect ratios of up to 2.0 were achieved. Experiments using pure water and varying aqueous concentrations of Triton-X 100 and bovine serum albumin (BSA) were performed. The axisymmetric drop shape oscillations were fit using the degenerate spherical shape modes. The frequency and decay values of the fundamental quadrupole and fourth order shape mode were analyzed. Several large amplitude nonlinear oscillation dynamics were observed. Shape entrainment of the higher modes by the fundamental quadrupole mode occurred. Amplitude- dependent effects were observed. The nonlinear frequency shift, where the oscillation frequency is found to decrease with larger amplitudes, was largely unaffected by the presence of surfactants. The percentage of time spent in the prolate shape over one oscillation cycle was found to increase with oscillation amplitude. This prolate shape bias was also unaffected by the addition of surfactants. These amplitude-dependent effects indicate that the nonlinearities are a function of the bulk properties and not the surface properties. BSA was found to greatly enhance the surface viscoelastic properties by increasing the total damping of the oscillation, while Triton had only a small influence on damping. The surface concentration of BSA was found to be diffusion-controlled over the time of the experiments, while the Triton diffusion rate was very rapid. Using the experimental frequency and decay values, the suface viscoelastic properties of surface dilatational viscosity ( ks ) and surface shear viscosity ( ms ) were found for varying surfactant concentrations using the transcendental equation of Lu

  14. On the performance of low pressure die-cast Al-Cu based automotive alloys: Role of additives

    NASA Astrophysics Data System (ADS)

    Zaki, Gergis Adel

    The present study focuses on the effect of alloying elements, namely, strontium (Sr), titanium (Ti), zirconium (Zr), scandium (Sc) and silver(Ag) individually or in combination, on the performance of a newly developed Al-2%Cu based alloy. A total of thirteen alloy compositions were used in the study. Tensile test bar castings were prepared employing the low pressure die casting (LPDC) technique. The test bars were solution heat treated at 495°C for 8 hours, followed by quenching in warm water, and then subjected to different isochronal aging treatments using an aging time of 5 hours and aging temperatures of 155°C, 180°C, 200°C, 240°C and 300°C. Tensile testing of as-cast and heat-treated test bars was carried out at room temperature using a strain rate of 4 x 10-4s-1. Five test bars were used per alloy composition/condition. Hardness measurements were also carried out on these alloys using a Brinell hardness tester. The microstructures of selected samples were examined using optical microscopy and electron probe microanalysis (EPMA). The results showed that adding Ti in the amount of 0.15 wt% in the form of Al-5%Ti-1%B master alloy is sufficient to refine the grains in the cast structure in the presence of 200 ppm Sr (0.02 wt%). Addition of Zr and Sc did not contribute further to the grain refining effect. The main role of addition of these two elements appeared in the formation of complex compounds with Al and Ti. Their presence resulted in extending the aging temperature range before the onset of softening. Mathematical analysis of the hardness and tensile data was carried out using the Minitab statistical software program. It was determined that the alloy containing (0.5wt% Zr + 0.15wt% Ti) is the most effective in maximizing the alloy tensile strength over the range of aging temperatures, from 155°C to 300°C. Addition of Ag is beneficial at high aging temperatures, in the range of 240°C-300°C. However, it is less effective compared to the (Zr + Ti

  15. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  16. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen diflouride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  17. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  18. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen difluoride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  19. 49 CFR 173.302b - Additional requirements for shipment of non-liquefied (permanent) compressed gases in UN pressure...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... may the internal pressure at 65 °C (149 °F) exceed the test pressure. (c) Fluorine, compressed, UN 1045 and Oxygen diflouride, compressed, UN 2190. Fluorine, compressed and Oxygen difluoride,...

  20. Dynamics of rotating and oscillating drops

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Trinh, E. H.; Croonquist, A. P.; Elleman, D. D.

    1987-01-01

    The dynamics of rotation and oscillation is investigated of a freely suspended liquid drop under the influence of surface tension and positioned inside an experimental apparatus by acoustic forces in the low acceleration environment of Spacelab 3. After a drop was observed to be spherical and stably located at the center of the chamber, it was set into rotation or oscillation by acoustic torque or modulated radiation pressure force.

  1. Generalized Charts for Determination of Pressure Drop of a High-speed Compressible Fluid in Heat-exchanger Passages I : Air Heated in Smooth Passages of Constant Area with Constant Wall Temperature

    NASA Technical Reports Server (NTRS)

    Valerino, Michael F

    1948-01-01

    In the present paper an analysis is made of the compressible-flow variations occurring in heat-exchanger passages. The results of the analysis describe the flow and heating characteristics for which specific flow passages can be treated as segments of generalized flow systems. The graphical representation of the flow variations in the generalized flow systems can then be utilized as working charts to determine directly the pressure changes occurring in any specific flow passage. On the basis of these results, working charts are constructed to handle the case of air heated at constant wall temperature under turbulent-flow conditions. A method is given of incorporating the effect on the heat-exchanger flow process of high temperature differential between passage wall and fluid as based on recent NACA experimental data. Good agreement is obtained between the experimental and the chart pressure-drop values for passage-wall average temperatures as high as 1752 degrees R (experimental limit) and for flow Mach numbers ranging from 0.32 to 1.00 (choke) at the passage exit.

  2. Youth Crime Drop. Report.

    ERIC Educational Resources Information Center

    Butts, Jeffrey A.

    This report examines the recent drop in violent crime in the United States, discussing how much of the decrease seen between 1995-99 is attributable to juveniles (under age 18 years) and older youth (18-24 years). Analysis of current FBI arrest data indicates that not only did America's violent crime drop continue through 1999, but falling youth…

  3. Axisymmetric Liquid Hanging Drops

    ERIC Educational Resources Information Center

    Meister, Erich C.; Latychevskaia, Tatiana Yu

    2006-01-01

    The geometry of drops hanging on a circular capillary can be determined by numerically solving a dimensionless differential equation that is independent on any material properties, which enables one to follow the change of the height, surface area, and contact angle of drops hanging on a particular capillary. The results show that the application…

  4. Drop Tower Physics

    ERIC Educational Resources Information Center

    Dittrich, William A.

    2014-01-01

    The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

  5. Inhibition of Condensation Frosting by Arrays of Hygroscopic Antifreeze Drops.

    PubMed

    Sun, Xiaoda; Damle, Viraj G; Uppal, Aastha; Linder, Rubin; Chandrashekar, Sriram; Mohan, Ajay R; Rykaczewski, Konrad

    2015-12-29

    The formation of frost and ice can have negative impacts on travel and a variety of industrial processes and is typically addressed by dispensing antifreeze substances such as salts and glycols. Despite the popularity of this anti-icing approach, some of the intricate underlying physical mechanisms are just being unraveled. For example, recent studies have shown that in addition to suppressing ice formation within its own volume, an individual salt saturated water microdroplet forms a region of inhibited condensation and condensation frosting (RIC) in its surrounding area. This occurs because salt saturated water, like most antifreeze substances, is hygroscopic and has water vapor pressure at its surface lower than water saturation pressure at the substrate. Here, we demonstrate that for macroscopic drops of propylene glycol and salt saturated water, the absolute RIC size can remain essentially unchanged for several hours. Utilizing this observation, we demonstrate that frost formation can be completely inhibited in-between microscopic and macroscopic arrays of propylene glycol and salt saturated water drops with spacing (S) smaller than twice the radius of the RIC (δ). Furthermore, by characterizing condensation frosting dynamics around various hygroscopic drop arrays, we demonstrate that they can delay complete frosting over of the samples 1.6 to 10 times longer than films of the liquids with equivalent volume. The significant delay in onset of ice nucleation achieved by dispensing propylene glycol in drops rather than in films is likely due to uniform dilution of the drops driven by thermocapillary flow. This transport mode is absent in the films, leading to faster dilution, and with that facilitated homogeneous nucleation, near the liquid-air interface. PMID:26651017

  6. A dominant role of oxygen additive on cold atmospheric-pressure He + O{sub 2} plasmas

    SciTech Connect

    Yang, Aijun; Liu, Dingxin E-mail: xhw@mail.xjtu.edu.cn; Rong, Mingzhe; Wang, Xiaohua E-mail: xhw@mail.xjtu.edu.cn; Kong, Michael G.

    2014-08-15

    We present in this paper how oxygen additive impacts on the cold atmospheric-pressure helium plasmas by means of a one-dimensional fluid model. For the oxygen concentration [O{sub 2}] > ∼0.1%, the influence of oxygen on the electron characteristics and the power dissipation becomes important, e.g., the electron density, the electron temperature in sheath, the electron-coupling power, and the sheath width decreasing by 1.6 to 16 folds with a two-log increase in [O{sub 2}] from 0.1% to 10%. Also the discharge mode evolves from the γ mode to the α mode. The reactive oxygen species are found to peak in the narrow range of [O{sub 2}] = 0.4%–0.9% in the plasmas, similar to their power-coupling values. This applies to their wall fluxes except for those of O* and O{sub 2}{sup −}. These two species have very short lifetimes, thus only when generated in boundary layers within several micrometers next to the electrode can contribute to the fluxes. The dominant reactive oxygen species and the corresponding main reactions are schematically presented, and their relations are quantified for selected applications.

  7. Coarsened Exact Matching of Phaco-Trabectome to Trabectome in Phakic Patients: Lack of Additional Pressure Reduction from Phacoemulsification

    PubMed Central

    Parikh, Hardik A.; Bussel, Igor I.; Schuman, Joel S.; Brown, Eric N.; Loewen, Nils A.

    2016-01-01

    Purpose To compare intraocular pressure (IOP) after trabectome-mediated ab interno trabeculectomy surgery in phakic patients (T) and trabectome with same session phacoemulsification (PT) using Coarsened Exact Matching. Although phacoemulsification is associated with IOP reduction when performed on its own, it is not known how much it contributes in PT. Methods Subjects were divided into phakic T and PT. Exclusion criteria were follow-up for <12 months and additional glaucoma surgery. Demographics were compared by the Mann-Whitney U test and chi-squared test for continuous and categorical variables, respectively. Multiple imputation was utilized to avoid eliminating data with missing values. Groups were then matched using Coarsened Exact Matching based on age, race, type of glaucoma, baseline IOP, and number of preoperative glaucoma medications. Univariate linear regression was used to examine IOP reduction after surgery; those variables that were statistically significant were included in the final multivariate regression model. Results A total of 753 cases were included (T: 255, PT: 498). When all variables except for age were kept constant, there was an additional IOP reduction of 0.05±0.01 mmHg conferred for every yearly increment in age. Every 1 mmHg increase in baseline IOP correlated to an additional IOP reduction of 0.80±0.02 mmHg. Phacoemulsification was not found to be a statistically significant contributor to IOP when comparing T and PT (p≥0.05). T had a 21% IOP reduction to 15.9±3.5 mmHg (p<0.01) while PT had an 18% reduction to 15.5±3.6 mmHg (p<0.01). Number of medications decreased (p<0.01) in both groups from 2.4±1.2 to 1.9±1.3 and from 2.3±1.1 to 1.7±1.3, respectively. Conclusion Phacoemulsification does not make a significant contribution to postoperative IOP or number of medications when combined with trabectome surgery in phakic patients. PMID:26895293

  8. Drop Tower Physics

    NASA Astrophysics Data System (ADS)

    Dittrich, William A. Toby

    2014-10-01

    The drop towers of yesteryear were used to make lead shot for muskets, as described in The Physics Teacher1 in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at the drop tower in Bremen, Germany. Using these drop towers, one can briefly investigate various physical systems operating in this near zero-g environment. The resulting "Drop Tower Physics" is a new and exciting way to challenge students with a physical example that requires solid knowledge of many basic physics principles, and it forces them to practice the scientific method. The question is, "How would a simple toy, like a pendulum, behave when it is suddenly exposed to a zero-g environment?" The student must then postulate a particular behavior, test the hypothesis against physical principles, and if the hypothesis conforms to these chosen physical laws, the student can formulate a final conclusion. At that point having access to a drop tower is very convenient, in that the student can then experimentally test his or her conclusion. The purpose of this discussion is to explain the response of these physical systems ("toys") when the transition is made to a zero-g environment and to provide video demonstrations of this behavior to support in-class discussions of Drop Tower Physics.

  9. Drop impact of suspensions

    NASA Astrophysics Data System (ADS)

    Thoraval, M.-J.; Boyer, F.; Sandoval Nava, E.; Dijksman, J. F.; Lohse, D.; Snoeijer, J. H.

    2014-11-01

    Drop impact studies have a wide range of applications, many of which involve complex fluids. We study here the liquid drop impact of a silver nano-particles dispersion on a solid glass surface. This dispersion is used for inkjet printing of functional electronic materials. When the impact velocity increases, the drop classically splashes into smaller droplets. However, it surprisingly stops splashing above a critical impact velocity. We combine high-speed imaging experiments with different characterizations of the dispersion to understand this transition to non-splashing.

  10. Heat loss and drag of spherical drop tube samples

    NASA Technical Reports Server (NTRS)

    Wallace, D. B.

    1982-01-01

    Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.

  11. Drop Tower Workshop

    NASA Technical Reports Server (NTRS)

    Urban, David

    2013-01-01

    Ground based microgravity facilities are an important proving ground for space experiments, ground-based research and space hardware risk mitigation. An overview of existing platforms will be discussed with an emphasis on drop tower capabilities. The potential for extension to partial gravity conditions will be discussed. Input will be solicited from attendees for their potential to use drop towers in the future and the need for enhanced capabilities (e.g. partial gravity)

  12. Modeling of drop breakup in the bag breakup regime

    NASA Astrophysics Data System (ADS)

    Wang, C.; Chang, S.; Wu, H.; Xu, J.

    2014-04-01

    Several analytic models for predicting the drop deformation and breakup have been developed over the last three decades, but modeling drop breakup in the bag-type regime is less reported. In this Letter, a breakup model has been proposed to predict the drop deformation length and breakup time in the bag-type breakup regime in a more accurate manner. In the present model, the drop deformation which is approximately as the displacement of the centre of mass (c. m.) along the axis located at the centre of the drop, and the movement of c. m. is obtained by solving the pressure balance equation. The effects of the drop deformation on the drop external aerodynamic force are considered in this model. Drop breakup occurs when the deformation length reaches the maximum value and the maximum deformation length is a function of Weber number. The performance and applicability of the proposed breakup model are tested against the published experimental data.

  13. Hanging drop crystal growth apparatus and method

    NASA Technical Reports Server (NTRS)

    Carter, Daniel C. (Inventor); Smith, Robbie E. (Inventor)

    1989-01-01

    An apparatus (10) is constructed having a cylindrical enclosure (16) within which a disc-shaped wicking element (18) is positioned. A well or recess (22) is cut into an upper side (24) of this wicking element, and a glass cover plate or slip (28) having a protein drop disposed thereon is sealably positioned on the wicking element (18), with drop (12) being positioned over well or recess (22). A flow of control fluid is generated by a programmable gradient former (16), with this control fluid having a vapor pressure that is selectively variable. This flow of control fluid is coupled to the wicking element (18) where control fluid vapor diffusing from walls (26) of the recess (22) is exposed to the drop (12), forming a vapor pressure gradient between the drop (12) and the control fluid vapor. Initially, this gradient is adjusted to draw solvent from the drop (12) at a relatively high rate, and as the critical supersaturation point is approached (the point at which crystal nucleation occurs), the gradient is reduced to more slowly draw solvent from the drop (12). This allows discrete protein molecules more time to orient themselves into an ordered crystalline lattice, producing protein crystals which, when processed by X-ray crystallography, possess a high degree of resolution.

  14. Drop pressure optimization in oil well drilling

    NASA Astrophysics Data System (ADS)

    Mellak, Abderrahmane; Benyounes, Khaled; Djeridi, Adel

    2014-10-01

    In this research work, we are interested in minimizing losses, existing when drilling an oil well. This would essentially improve the load losses by acting on the rheological parameters of the hydraulic and drilling mud. For this, rheological tests were performed using a six-speed rotary viscometer (FANN 35). We used several rheological models to accurately describe the actual rheological behavior of drilling mud oil-based, according to the Pearson's coefficient and to the standard deviation. To model the problem, we established a system of equations that describe the essential to highlight purpose and various constraints that allow for achieving this goal. To solve the problem, we developed a computer program that solves the obtained equations in Visual Basic language system. Hydraulic and rheological calculation was made for in situ application. This allowed us to estimate the distribution of losses in the well.

  15. Rain Drop Charge Sensor

    NASA Astrophysics Data System (ADS)

    S, Sreekanth T.

    begin{center} Large Large Rain Drop Charge Sensor Sreekanth T S*, Suby Symon*, G. Mohan Kumar (1) , S. Murali Das (2) *Atmospheric Sciences Division, Centre for Earth Science Studies, Thiruvananthapuram 695011 (1) D-330, Swathi Nagar, West Fort, Thiruvananthapuram 695023 (2) Kavyam, Manacaud, Thiruvananthapuram 695009 begin{center} ABSTRACT To study the inter-relations with precipitation electricity and precipitation microphysical parameters a rain drop charge sensor was designed and developed at CESS Electronics & Instrumentation Laboratory. Simultaneous measurement of electric charge and fall speed of rain drops could be done using this charge sensor. A cylindrical metal tube (sensor tube) of 30 cm length is placed inside another thick metal cover opened at top and bottom for electromagnetic shielding. Mouth of the sensor tube is exposed and bottom part is covered with metal net in the shielding cover. The instrument is designed in such a way that rain drops can pass only through unhindered inside the sensor tube. When electrically charged rain drops pass through the sensor tube, it is charged to the same magnitude of drop charge but with opposite polarity. The sensor tube is electrically connected the inverted input of a current to voltage converter operational amplifier using op-amp AD549. Since the sensor is electrically connected to the virtual ground of the op-amp, the charge flows to the ground and the generated current is converted to amplified voltage. This output voltage is recorded using a high frequency (1kHz) voltage recorder. From the recorded pulse, charge magnitude, polarity and fall speed of rain drop are calculated. From the fall speed drop diameter also can be calculated. The prototype is now under test running at CESS campus. As the magnitude of charge in rain drops is an indication of accumulated charge in clouds in lightning, this instrument has potential application in the field of risk and disaster management. By knowing the charge

  16. Rotating drops of axion dark matter

    NASA Astrophysics Data System (ADS)

    Davidson, Sacha; Schwetz, Thomas

    2016-06-01

    We consider how QCD axions produced by the misalignment mechanism could form galactic dark matter halos. We recall that stationary, gravitationally stable axion field configurations have the size of an asteroid with masses of order 10-13M⊙ (because gradient pressure is insufficient to support a larger object). We call such field configurations "drops." We explore whether rotating drops could be larger, and find that their mass could increase by a factor ˜10 . This mass is comparable to the mass of miniclusters generated from misalignment axions in the scenario where the axion is born after inflation. We speculate that misalignment axions today are in the form of drops, contributing to dark matter like a distribution of asteroids (and not as a coherent oscillating background field). We consider some observational signatures of the drops, which seem consistent with a galactic halo made of axion dark matter.

  17. Mixing in colliding, ultrasonically levitated drops.

    PubMed

    Chainani, Edward T; Choi, Woo-Hyuck; Ngo, Khanh T; Scheeline, Alexander

    2014-02-18

    Lab-in-a-drop, using ultrasonic levitation, has been actively investigated for the last two decades. Benefits include lack of contact between solutions and an apparatus and a lack of sample cross-contamination. Understanding and controlling mixing in the levitated drop is necessary for using an acoustically levitated drop as a microreactor, particularly for studying kinetics. A pulsed electrostatic delivery system enables addition and mixing of a desired-volume droplet with the levitated drop. Measurement of mixing kinetics is obtained by high-speed video monitoring of a titration reaction. Drop heterogeneity is visualized as 370 nl of 0.25 M KOH (pH: 13.4) was added to 3.7 μL of 0.058 M HCl (pH: 1.24). Spontaneous mixing time is about 2 s. Following droplet impact, the mixed drop orbits the levitator axis at about 5 Hz during homogenization. The video's green channel (maximum response near 540 nm) shows the color change due to phenolphthalein absorption. While mixing is at least an order of magnitude faster in the levitated drop compared with three-dimensional diffusion, modulation of the acoustic waveform near the surface acoustic wave resonance frequency of the levitated drop does not substantially reduce mixing time. PMID:24460103

  18. Liquid metal drop ejection

    NASA Technical Reports Server (NTRS)

    Khuri-Yakub, B. T.

    1993-01-01

    The aim of this project was to demonstrate the possibility of ejecting liquid metals using drop on demand printing technology. The plan was to make transducers for operation in the 100 MHz frequency range and to use these transducers to demonstrate the ability to eject drops of liquid metals such as gallium. Two transducers were made by indium bonding piezoelectric lithium niobate to quartz buffer rods. The lithium niobate plates were thinned by mechanical polishing to a thickness of 37 microns for operation at 100 MHz. Hemispherical lenses were polished in the opposite ends of the buffer rods. The lenses, which focus the sound waves in the liquid metal, had an F-number equals 1. A mechanical housing was made to hold the transducers and to allow precise control over the liquid level above the lens. We started by demonstrating the ability to eject drops of water on demand. The drops of water had a diameter of 15 microns which corresponds to the wavelength of the sound wave in the water. A videotape of this ejection was made. We then used a mixture of Gallium and Indium (used to lower the melting temperature of the Gallium) to demonstrate the ejection of liquid metal drops. This proved to be difficult because of the oxide skin which forms on the surface of the liquid. In some instances, we were able to eject metal drops, however, this was not consistent and reproducible. An experiment was set up at NASA-Lewis to stabilize the process of drop on demand liquid metal ejection. The object was to place the transducer and liquid metal in a vacuum station so that no oxide would form on the surface. We were successful in demonstrating that liquid metals could be ejected on demand and that this technology could be used for making sheet metal in space.

  19. Primary acoustic signal structure during free falling drop collision with a water surface

    NASA Astrophysics Data System (ADS)

    Chashechkin, Yu. D.; Prokhorov, V. E.

    2016-04-01

    Consistent optical and acoustic techniques have been used to study the structure of hydrodynamic disturbances and acoustic signals generated as a free falling drop penetrates water. The relationship between the structures of hydrodynamic and acoustic perturbations arising as a result of a falling drop contacting with the water surface and subsequent immersion into water is traced. The primary acoustic signal is characterized, in addition to stably reproduced features (steep leading edge followed by long decay with local pressure maxima), by irregular high-frequency packets, which are studied for the first time. Reproducible experimental data are used to recognize constant and variable components of the primary acoustic signal.

  20. Numerical analysis of the effect of acetylene and benzene addition to low-pressure benzene-rich flat flames on polycyclic aromatic hydrocarbon formation

    SciTech Connect

    Kunioshi, Nilson; Komori, Seisaku; Fukutani, Seishiro

    2006-10-15

    A modification of the CHEMKIN II package has been proposed for modeling addition of an arbitrary species at an arbitrary temperature to an arbitrary distance from the burner along a flat flame. The modified program was applied to the problem of addition of acetylene or benzene to different positions of a 40-Torr, {phi}=2.4 benzene/O{sub 2}/40%-N{sub 2} premixed flame to reach final equivalence ratios of {phi}=2.5 and 2.681. The results obtained showed that acetylene addition to early positions of the flame led to significant increase in pyrene production rates, but pyrene concentrations were lower in the flames with acetylene addition in both the {phi}=2.5 and 2.681 cases. Addition of benzene to the flame did not alter pyrene production rates in either the {phi}=2.5 or 2.681 cases; however, for {phi}=2.5, pyrene concentrations increased with benzene addition, while for {phi}=2.681, pyrene contents decreased in comparison to the correspondent flames with no addition. Acetylene addition led to a significant increase in pyrene production rates, but the pyrene levels dropped due to increase in the flow velocity. Pyrene production rates were not sensitive to benzene addition, but pyrene contents increased with benzene addition when the flow velocity decreased. These results show that PAH concentration changes accompanying species addition to flames should be interpreted carefully, because an increase or decrease in the content of a PAH species does not necessarily reflect an effect on its formation rate or mechanism. (author)

  1. Drying drops of blood

    NASA Astrophysics Data System (ADS)

    Brutin, David; Sobac, Benjamin; Loquet, Boris; Sampol, José.

    2010-11-01

    The drying of a drop of human blood is fascinating by the complexity of the physical mechanisms that occur as well as the beauty of the phenomenon which has never been previously evidenced in the literature. The final stage of full blood evaporation reveals for a healthy person the same regular pattern with a good reproducibility. Other tests on anemia and hyperlipidemic persons were performed and presented different patterns. By means of digital camera, the influence of the motion of red blood cells (RBCs) which represent about 50% of the blood volume, is revealed as well as its consequences on the final stages of drying. The mechanisms which lead to the final pattern of dried blood drops are presented and explained on the basis of fluid and solid mechanics in conjunction with the principles of hematology. Our group is the first to evidence that the specific regular patterns characteristic of a healthy individual do not appear in a dried drop of blood from a person with blood disease. Blood is a complex colloidal suspension for which the flow motion is clearly non-Newtonian. When drops of blood evaporate, all the colloids are carried by the flow motion inside the drop and interact.

  2. Combined effects of high pressure processing and addition of soy sauce and olive oil on safety and quality characteristics of chicken breast meat.

    PubMed

    Kruk, Zbigniew A; Kim, Hyun Joo; Kim, Yun Ji; Rutley, David L; Jung, Samooel; Lee, Soo Kee; Jo, Cheorun

    2014-02-01

    This study was conducted to evaluate the combined effect of high pressure (HP) with the addition of soy sauce and/or olive oil on the quality and safety of chicken breast meats. Samples were cut into 100 g pieces and 10% (w/w) of soy sauce (SS), 10% (w/w) of olive oil (OO), and a mixture of both 5% of soy sauce and 5% olive oil (w/w) (SO) were pressurized into meat with high pressure at 300 or 600 MPa. Cooking loss was lower in OO samples than SS samples. With increased pressure to 600 MPa, the oleic acid content of OO samples increased. The total unsaturated fatty acids were the highest in SO and OO 600 MPa samples. Lipid oxidation was retarded by addition of olive oil combined with HP. The addition of olive oil and soy sauce followed by HP decreased the amount of volatile basic nitrogen during storage and reduced the population of pathogens. Sensory evaluation indicated that the addition of olive oil enhanced the overall acceptance and willingness to buy. In conclusion, the combination of HP with the addition of soy sauce and/or olive oil is an effective technology that can improve chemical, health, sensory qualities and safety of chicken breast. PMID:25049950

  3. Combined Effects of High Pressure Processing and Addition of Soy Sauce and Olive Oil on Safety and Quality Characteristics of Chicken Breast Meat

    PubMed Central

    Kruk, Zbigniew A.; Kim, Hyun Joo; Kim, Yun Ji; Rutley, David L.; Jung, Samooel; Lee, Soo Kee; Jo, Cheorun

    2014-01-01

    This study was conducted to evaluate the combined effect of high pressure (HP) with the addition of soy sauce and/or olive oil on the quality and safety of chicken breast meats. Samples were cut into 100 g pieces and 10% (w/w) of soy sauce (SS), 10% (w/w) of olive oil (OO), and a mixture of both 5% of soy sauce and 5% olive oil (w/w) (SO) were pressurized into meat with high pressure at 300 or 600 MPa. Cooking loss was lower in OO samples than SS samples. With increased pressure to 600 MPa, the oleic acid content of OO samples increased. The total unsaturated fatty acids were the highest in SO and OO 600 MPa samples. Lipid oxidation was retarded by addition of olive oil combined with HP. The addition of olive oil and soy sauce followed by HP decreased the amount of volatile basic nitrogen during storage and reduced the population of pathogens. Sensory evaluation indicated that the addition of olive oil enhanced the overall acceptance and willingness to buy. In conclusion, the combination of HP with the addition of soy sauce and/or olive oil is an effective technology that can improve chemical, health, sensory qualities and safety of chicken breast. PMID:25049950

  4. Planar microfluidic drop splitting and merging.

    PubMed

    Collignon, Sean; Friend, James; Yeo, Leslie

    2015-04-21

    Open droplet microfluidic platforms offer attractive alternatives to closed microchannel devices, including lower fabrication cost and complexity, significantly smaller sample and reagent volumes, reduced surface contact and adsorption, as well as drop scalability, reconfigurability, and individual addressability. For these platforms to be effective, however, they require efficient schemes for planar drop transport and manipulation. While there are many methods that have been reported for drop transport, it is far more difficult to carry out other drop operations such as dispensing, merging and splitting. In this work, we introduce a novel alternative to merge and, more crucially, split drops using laterally-offset modulated surface acoustic waves (SAWs). The energy delivery into the drop is divided into two components: a small modulation amplitude excitation to initiate weak rotational flow within the drop followed by a short burst in energy to induce it to stretch. Upon removal of the SAW energy, capillary forces at the center of the elongated drop cause the liquid in this capillary bridge region to drain towards both ends of the drop, resulting in its collapse and therefore the splitting of the drop. This however occurs only below a critical Ohnesorge number, which is a balance between the viscous forces that retard the drainage and the sufficiently large capillary forces that cause the liquid bridge to pinch. We show the possibility of reliably splitting drops into two equal sized droplets with an average deviation in their volumes of only around 4% and no greater than 10%, which is comparable to the 7% and below splitting deviation obtained with electrowetting drop splitting techniques. In addition, we also show that it is possible to split the drop asymmetrically to controllably and reliably produce droplets of different volumes. Such potential as well as the flexibility in tuning the device to operate on drops of different sizes without requiring electrode

  5. Airflows generated by an impacting drop.

    PubMed

    Bischofberger, Irmgard; Ray, Bahni; Morris, Jeffrey F; Lee, Taehun; Nagel, Sidney R

    2016-03-28

    A drop impacting a solid surface with sufficient velocity will splash and emit many small droplets. However, lowering the ambient air pressure suppresses splashing completely. This effect, robustly found for different liquid and substrate properties, raises the fundamental question of how air affects a spreading drop. In a combined experimental and numerical study we characterize the flow of air induced by the drop after it hits the substrate, using a modified Schlieren optics technique combined with high-speed video imaging and Lattice-Boltzmann simulations. Our experiments reveal the emergence of air structures on different length scales. On large scales, the airflow induced in the drop's wake leads to vortex structures due to interaction with the substrate. On smaller scales, we visualize a ring structure above the outer edge of the spreading liquid generated by the spreading of the drop. Our simulations reveal the interaction between the wake vorticity and the flows originating from the rapidly escaping air from below the impacting drop. We show that the vorticity is governed by a balance between inertial and viscous forces in the air, and is unrelated to the splashing threshold. PMID:26809314

  6. Drop rebound in clouds and precipitation

    NASA Technical Reports Server (NTRS)

    Ochs, H. T., III; Beard, K. V.

    1982-01-01

    The possibility of rebound for colliding cloud drops was measured by determining the collection efficiency. The collection efficiency for 17 size pairs of relatively uncharged drops in over 500 experimental runs was measured using two techniques. The collection efficiencies fall in a narrow range of 0.60 to 0.70 even though the collection drop was varied between 63 and 326 microns and the size ratio from 0.05 to 0.33. In addition the measured values of collection efficiencies (Epsilon) were below the computed values of collision efficiencies (E) for rigid spheres. Therefore it was concluded that rebound was occurring for these sizes since inferred coalescence (epsilon = Epsilon/E) efficiencies are about 0.6 yo 0.8. At a very small size ratio (r/R = p = 0.05, R = 326 microns) the coalescence efficiency inferred is in good agreement with the experimental findings for a supported collector drop. At somewhat large size ratios the inferred values of epsilon are well above results of supported drop experiments, but show a slight correspondence in collected drop size dependency to two models of drop rebound. At a large size ratio (p = 0.73, R = 275) the inferred coalescence efficiency is significantly different from all previous results.

  7. Polymer-additive extraction via pressurized fluids and organic solvents of variously cross-linked poly(methylmethacrylates).

    PubMed

    Nazem, N; Taylor, L T

    2002-04-01

    Variously cross-linked poly(methylmethacrylates) (PMMAs) are synthesized with three additives incorporated at theoretically 1000 microg of the additive per gram of prepared polymer. The additives are Irganox 1010, Irganox 1076, and Irgafos 168. The in-house" synthesized polyacrylates are then subjected to supercritical fluid extraction (SFE) to determine if additive recovery is a function of percent cross-linking. Although considerable work in this regard has been performed with non-cross-linked polyolefins, the literature is lacking regarding polyacrylates. Some additive degradation apparently occurs during the synthesis, as judged by the increased complexity of the extract high-performance liquid chromatographic trace and the low percent recoveries observed especially for the Irganoxes. For low polymer cross-linking (1%), it appears that both PMMA synthetic reproducibility and readily observed polymer swelling during SFE are serious issues that adversely affect additive percent recovery and precision of results. Higher percent cross-linking yields more consistent analytical data than low percent cross-linking, even though the amount of additive extracted in all PMMA samples (regardless of cross-linking percentage) is essentially the same whether the extraction is via SFE or liquid-solid extraction with methylene chloride. Results for comparably cross-linked poly(ethylmethacrylate) and poly(butylmethacrylate) are similar to PMMA. PMID:12004935

  8. Acoustic forcing of a liquid drop

    NASA Technical Reports Server (NTRS)

    Lyell, M. J.

    1992-01-01

    The development of systems such as acoustic levitation chambers will allow for the positioning and manipulation of material samples (drops) in a microgravity environment. This provides the capability for fundamental studies in droplet dynamics as well as containerless processing work. Such systems use acoustic radiation pressure forces to position or to further manipulate (e.g., oscillate) the sample. The primary objective was to determine the effect of a viscous acoustic field/tangential radiation pressure forcing on drop oscillations. To this end, the viscous acoustic field is determined. Modified (forced) hydrodynamic field equations which result from a consistent perturbation expansion scheme are solved. This is done in the separate cases of an unmodulated and a modulated acoustic field. The effect of the tangential radiation stress on the hydrodynamic field (drop oscillations) is found to manifest as a correction to the velocity field in a sublayer region near the drop/host interface. Moreover, the forcing due to the radiation pressure vector at the interface is modified by inclusion of tangential stresses.

  9. Jumps, somersaults, and symmetry breaking in Leidenfrost drops.

    PubMed

    Chen, Simeng; Bertola, Volfango

    2016-08-01

    When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (∼100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops. We also show that non-Newtonian effects play little role in the energy distribution during drop impact, while the main effect is due to the symmetry break observed during the retraction of low-viscosity drops. PMID:27627234

  10. Digitizing of drop table output

    SciTech Connect

    Muncy, K.

    1984-01-01

    The method for monitoring and analyzing the drop pulses from the MTS1212 drop table system has been upgraded from a labor intensive manual system to an automatic digital system. The pulse from each drop is recorded, analyzed and printed out. The data printed out includes all product information, the drop parameters calculated and a plot of the drop pulse. Some of the advantages of this system, besides the replacement of old and obsolete equipment, include the dropping of the repeatability check requirement, ease of operation, complete automatic documentation of each drop, no need to take Polaroid pictures of a drop nor is it necessary to have a drop film read by the film analysis group. Data comparisons between the old method and the new digital method have been very favorable.

  11. Drop tube technical tasks

    NASA Technical Reports Server (NTRS)

    Workman, G. L.

    1986-01-01

    Criteria, using fundamental thermochemical dynamics, were developed to assist a scientist using the Drop Tube Facility in designing a good experiment. The types of parameters involved in designing the experiments include the type of furnace, the type of atmosphere, and in general which materials are better behaved than others as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in the cooling curve during the drops. A beginning was to consider the effect of oxygen and other gases upon the amount of undercooling observed. The starting point of the thermochemistry was given by Ellingham and later transformed into what is known as the Richardson Chart. The effect of surface oxidations upon the nucleation phenomena can be observed in each specimen.

  12. Effect of alkaline addition on anaerobic sludge digestion with combined pretreatment of alkaline and high pressure homogenization.

    PubMed

    Fang, Wei; Zhang, Panyue; Zhang, Guangming; Jin, Shuguang; Li, Dongyi; Zhang, Meixia; Xu, Xiangzhe

    2014-09-01

    To improve anaerobic digestion efficiency, combination pretreatment of alkaline and high pressure homogenization was applied to pretreat sewage sludge. Effect of alkaline dosage on anaerobic sludge digestion was investigated in detail. SCOD of sludge supernatant significantly increased with the alkaline dosage increase after the combined pretreatment because of sludge disintegration. Organics were significantly degraded after the anaerobic digestion, and the maximal SCOD, TCOD and VS removal was 73.5%, 61.3% and 43.5%, respectively. Cumulative biogas production, methane content in biogas and biogas production rate obviously increased with the alkaline dosage increase. Considering both the biogas production and alkaline dosage, the optimal alkaline dosage was selected as 0.04 mol/L. Relationships between biogas production and sludge disintegration showed that the accumulative biogas was mainly enhanced by the sludge disintegration. The methane yield linearly increased with the DDCOD increase as Methane yield (ml/gVS)=4.66 DDCOD-9.69. PMID:24703958

  13. Glaucoma eye drops adverse skin reactions.

    PubMed

    Cantisani, Carmen; Ambrifi, Marina; Frascani, Federica; Fazia, Gilda; Paolino, Giovanni; Lisi, Roberto; Calvieri, Stefano

    2014-01-01

    The term "Glaucoma" is used to describe a number of diseases of the eye characterized by a particular form of optic nerve damage that is often associated with high intraocular pressure (IOP). The open-angle glaucoma is the most common form that is also referred to as chronic glaucoma. This is described as an optic neuropathy with multifactorial nature in which there is a loss of characteristics of the optic nerve fibers. Therapeutic options for the treatment of this disease are different, you can take advantage of eye drops, laser therapy and conventional surgery or more combined treatments. Medicated eye drops are the most common way to treat glaucoma. Although eye drops are widely used, adverse reactions are not frequently observed and described. In particular, the adverse skin reactions are not frequently described in the literature, but often seen in dermatologic clinic, we reported their skin reactions and possible alternative treatments described in literature and their patent applications. PMID:25487259

  14. Coalescing drops in microfluidic parking networks: A multifunctional platform for drop-based microfluidics

    PubMed Central

    Bithi, Swastika S.; Wang, William S.; Sun, Meng; Blawzdziewicz, Jerzy; Vanapalli, Siva A.

    2014-01-01

    Multiwell plate and pipette systems have revolutionized modern biological analysis; however, they have disadvantages because testing in the submicroliter range is challenging, and increasing the number of samples is expensive. We propose a new microfluidic methodology that delivers the functionality of multiwell plates and pipettes at the nanoliter scale by utilizing drop coalescence and confinement-guided breakup in microfluidic parking networks (MPNs). Highly monodisperse arrays of drops obtained using a hydrodynamic self-rectification process are parked at prescribed locations in the device, and our method allows subsequent drop manipulations such as fine-gradation dilutions, reactant addition, and fluid replacement while retaining microparticles contained in the sample. Our devices operate in a quasistatic regime where drop shapes are determined primarily by the channel geometry. Thus, the behavior of parked drops is insensitive to flow conditions. This insensitivity enables highly parallelized manipulation of drop arrays of different composition, without a need for fine-tuning the flow conditions and other system parameters. We also find that drop coalescence can be switched off above a critical capillary number, enabling individual addressability of drops in complex MPNs. The platform demonstrated here is a promising candidate for conducting multistep biological assays in a highly multiplexed manner, using thousands of submicroliter samples. PMID:25379078

  15. Coalescing drops in microfluidic parking networks: A multifunctional platform for drop-based microfluidics.

    PubMed

    Bithi, Swastika S; Wang, William S; Sun, Meng; Blawzdziewicz, Jerzy; Vanapalli, Siva A

    2014-05-01

    Multiwell plate and pipette systems have revolutionized modern biological analysis; however, they have disadvantages because testing in the submicroliter range is challenging, and increasing the number of samples is expensive. We propose a new microfluidic methodology that delivers the functionality of multiwell plates and pipettes at the nanoliter scale by utilizing drop coalescence and confinement-guided breakup in microfluidic parking networks (MPNs). Highly monodisperse arrays of drops obtained using a hydrodynamic self-rectification process are parked at prescribed locations in the device, and our method allows subsequent drop manipulations such as fine-gradation dilutions, reactant addition, and fluid replacement while retaining microparticles contained in the sample. Our devices operate in a quasistatic regime where drop shapes are determined primarily by the channel geometry. Thus, the behavior of parked drops is insensitive to flow conditions. This insensitivity enables highly parallelized manipulation of drop arrays of different composition, without a need for fine-tuning the flow conditions and other system parameters. We also find that drop coalescence can be switched off above a critical capillary number, enabling individual addressability of drops in complex MPNs. The platform demonstrated here is a promising candidate for conducting multistep biological assays in a highly multiplexed manner, using thousands of submicroliter samples. PMID:25379078

  16. Mechanisms of radical formation in beef and chicken meat during high pressure processing evaluated by electron spin resonance detection and the addition of antioxidants.

    PubMed

    Bolumar, Tomas; Andersen, Mogens L; Orlien, Vibeke

    2014-05-01

    The generation of radicals during high pressure (HP) processing of beef loin and chicken breast was studied by spin trapping and electron spin resonance detection. The pressurization resulted in a higher level of spin adducts in the beef loin than in the chicken breast. It was shown that radicals were formed in the sarcoplasmic and myofibrillar fractions as well as in the non-soluble protein fraction due to the HP treatment, indicating that other radicals than iron-derived radicals were formed, and most likely protein-derived radicals. The addition of iron as well as the natural antioxidants caffeic acid, rosemary extract, and ascorbic acid resulted in an increased formation of radicals during the HP treatment, whereas addition of ethylendiamintetraacetic acid (EDTA) reduced the radical formation. This suggests that iron-species (protein-bound or free) catalyses the formation of radicals when meat systems are submitted to HP. PMID:24360471

  17. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25507326

  18. Atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry of friction modifier additives analyzed directly from base oil solutions.

    PubMed

    Widder, Lukas; Brennerb, Josef; Huttera, Herbert

    2014-01-01

    To develop new products and to apply measures of quality control quick and simple accessibility of additive composition in automo- tive lubrication is important. The aim of this study was to investigate the possibility of analyzing organic friction modifier additives by means of atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry [AP-MALDI-MS] from lubricant solu- tions without the use of additional separation techniques. Analyses of selected friction modifier ethoxylated tallow amines and oleic acid amide were compared using two ionization methods, positive-ion electrospray ionization (ESI) and AP-MALDI, using a LTQ Orbitrap mass spectrometer. Pure additives were characterized from solvent solutions, as well as from synthetic and mineral base oil mixtures. Detected ions of pure additive samples consisted mainly of [M + H]+, but also alkaLi metal adducts [M + Na]+ and [M + K]+ could be seen. Characterizations of blends of both friction modifiers from the base oil mixtures were carried out as well and showed significant inten- sities for several additive peaks. Thus, this work shows a method to directly analyze friction modifier additives used in the automotive industry from an oil blend via the use of AP-MALDI without any further separation steps. The method presented will further simplify the acquisition of data on lubricant composition and additives. Furthermore, it allows the perspective of analyzing additive reaction products directly from formulated oil blends. PMID:25420342

  19. Electrochemistry in an acoustically levitated drop.

    PubMed

    Chainani, Edward T; Ngo, Khanh T; Scheeline, Alexander

    2013-02-19

    Levitated drops show potential as microreactors, especially when radicals are present as reactants or products. Solid/liquid interfaces are absent or minimized, avoiding adsorption and interfacial reaction of conventional microfluidics. We report amperometric detection in an acoustically levitated drop with simultaneous ballistic addition of reactant. A gold microelectrode sensor was fabricated with a lithographic process; active electrode area was defined by a photosensitive polyimide mask. The microdisk gold working electrode of radius 19 μm was characterized using ferrocenemethanol in aqueous buffer. Using cyclic voltammetry, the electrochemically active surface area was estimated by combining a recessed microdisk electrode model with the Randles-Sevcik equation. Computer-controlled ballistic introduction of reactant droplets into the levitated drop was developed. Chronoamperometric measurements of ferrocyanide added ballistically demonstrate electrochemical monitoring using the microfabricated electrode in a levitated drop. Although concentration increases with time due to drop evaporation, the extent of concentration is predictable with a linear evaporation model. Comparison of diffusion-limited currents in pendant and levitated drops show that convection arising from acoustic levitation causes an enhancement of diffusion-limited current on the order of 16%. PMID:23351154

  20. Leidenfrost Drop on a Step

    NASA Astrophysics Data System (ADS)

    Lagubeau, Guillaume; Le Merrer, Marie; Clanet, Christophe; Quere, David

    2008-11-01

    When deposited on a hot plate, a water droplet evaporates quickly. However, a vapor film appears under the drop above a critical temperature, called Leidenfrost temperature, which insulates the drop from its substrate. Linke & al (2006) reported a spontaneous movement of such a drop, when deposited on a ratchet. We study here the case of a flat substrate decorated with a single micrometric step. The drop is deposited on the lower part of the plate and pushed towards the step at small constant velocity. If the kinetic energy of the drop is sufficient, it can climb up the step. In that case, depending on the substrate temperature, the drop can either be decelerated or accelerated by the step. We try to understand the dynamics of these drops, especially the regime where they accelerate. Taking advantage of this phenomenon, we could then build a multiple-step setup, making it possible for a Leidenfrost drop to climb stairs.

  1. Drop foot corrective device

    NASA Technical Reports Server (NTRS)

    Deis, B. C. (Inventor)

    1986-01-01

    A light weight, economical device to alleviate a plurality of difficulties encountered in walking by a victim suffering from a drop foot condition is discussed. A legband girdles the leg below the knee and above the calf providing an anchor point for the upper end of a ligament having its lower end attached to a toe of a shoe or a toe on the foot. The ligament is of such length that the foot is supported thereby and retained in a normal position during walking.

  2. How to Use Ear Drops

    MedlinePlus

    How to Use Ear Drops(Having someone else give you the ear drops may make this procedure easier.) Wash your hands thoroughly with soap and ... facecloth and then dry your ear. Warm the drops to near body temperature by holding the container ...

  3. Synthetic metallic dialkydithiocarbamates as antiwear and extreme-pressure additives for lubricating oils: Role of metal on their effectiveness

    SciTech Connect

    Tuli, D.K.; Sarin, R.; Gupta, A.K.

    1995-04-01

    Dialkydithiocarbamates of five metals have been synthesized in pure form by following a simple general method. The alkyl chain in each of these compounds has been kept the same so as to observe the performance variations due to metal ions. The EP properties expressed as load wear index and weld load indicated the highest performance by Bi followed by Pb, Sb, Zn and Mo. The antiwear properties in terms of wear scar diameter, relative anti-wear effectiveness and mean average wear scar diameter show a performance order of Bi > Pb > Sb > Zn > Mo. The large ionic radius metals (Bi, Pb & Sb) had the best overall load-carrying performance and their effectiveness increased substantially when the additive concentration was more than 0.004 gm atom/Kg. The results suggest that Bi has good potential to replace toxic Pb and Sb from existing lubrication systems. 18 refs., 7 refs., 1 tab.

  4. Venturi nozzle effects on fuel drop size and nitrogen oxide emissions

    NASA Technical Reports Server (NTRS)

    Johnson, S. M.

    1982-01-01

    The effect of a venturi nozzle on the Sauter mean diameter of a water spray produced by a simplex pressure atomizing injector in a swirling airflow was determined. A Malvern particle and droplet size distribution analyzer, Type S.T. 1800, was used to measure D sub 32 of the water sprays. The water spray was studied at ambient temperature (293 K) and atmospheric pressure. The venturi reduced D sub 32 by an average of 30 percent when installed with a simplex injector and air swirler. The venturi primarily improved atomization of the injector spray by increasing relative air velocity. The small drop size enhanced vaporization and therefore decreased oxides of nitrogen in a combustor. The decrease in drop size provided by the addition of a venturi explains the results obtained in a previous small scale research combustor wherein NOx emission indices decreased as a result of this hardware modification.

  5. Low blood pressure

    MedlinePlus

    Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH ... Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause ...

  6. Low blood pressure

    MedlinePlus

    Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH ... Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause problems for ...

  7. Controlling charge on levitating drops.

    PubMed

    Hilger, Ryan T; Westphall, Michael S; Smith, Lloyd M

    2007-08-01

    Levitation technologies are used in containerless processing of materials, as microscale manipulators and reactors, and in the study of single drops and particles. Presented here is a method for controlling the amount and polarity of charge on a levitating drop. The method uses single-axis acoustic levitation to trap and levitate a single, initially neutral drop with a diameter between 400 microm and 2 mm. This drop is then charged in a controllable manner using discrete packets of charge in the form of charged drops produced by a piezoelectric drop-on-demand dispenser equipped with a charging electrode. The magnitude of the charge on the dispensed drops can be adjusted by varying the voltage applied to the charging electrode. The polarity of the charge on the added drops can be changed allowing removal of charge from the trapped drop (by neutralization) and polarity reversal. The maximum amount of added charge is limited by repulsion of like charges between the drops in the trap. This charging scheme can aid in micromanipulation and the study of charged drops and particles using levitation. PMID:17580951

  8. A perspective on the interfacial properties of nanoscopic liquid drops

    NASA Astrophysics Data System (ADS)

    Malijevský, Alexandr; Jackson, George

    2012-11-01

    The structural and interfacial properties of nanoscopic liquid drops are assessed by means of mechanical, thermodynamical, and statistical mechanical approaches that are discussed in detail, including original developments at both the macroscopic level and the microscopic level of density functional theory (DFT). With a novel analysis we show that a purely macroscopic (static) mechanical treatment can lead to a qualitatively reasonable description of the surface tension and the Tolman length of a liquid drop; the latter parameter, which characterizes the curvature dependence of the tension, is found to be negative and has a magnitude of about a half of the molecular dimension. A mechanical slant cannot, however, be considered satisfactory for small finite-size systems where fluctuation effects are significant. From the opposite perspective, a curvature expansion of the macroscopic thermodynamic properties (density and chemical potential) is then used to demonstrate that a purely thermodynamic approach of this type cannot in itself correctly account for the curvature correction of the surface tension of liquid drops. We emphasize that any approach, e.g., classical nucleation theory, which is based on a purely macroscopic viewpoint, does not lead to a reliable representation when the radius of the drop becomes microscopic. The description of the enhanced inhomogeneity exhibited by small drops (particularly in the dense interior) necessitates a treatment at the molecular level to account for finite-size and surface effects correctly. The so-called mechanical route, which corresponds to a molecular-level extension of the macroscopic theory of elasticity and is particularly popular in molecular dynamics simulation, also appears to be unreliable due to the inherent ambiguity in the definition of the microscopic pressure tensor, an observation which has been known for decades but is frequently ignored. The union of the theory of capillarity (developed in the nineteenth

  9. Drop deployment system for crystal growth apparatus

    NASA Technical Reports Server (NTRS)

    Rhodes, Percy (Inventor); Snyder, Robert S. (Inventor); Pusey, Marc L. (Inventor)

    1990-01-01

    A crystal growth apparatus is presented. It utilizes a vapor diffusion method for growing protein crystals, and particularly such an apparatus wherein a ball mixer is used to mix the fluids that form a drop within which crystals are grown. Particular novelty of this invention lies in utilizing a ball mixer to completely mix the precipitate and protein solutions prior to forming the drop. Additional novelty lies in details of construction of the vials, the fluid deployment system, and the fluid storage system of the preferred embodiment.

  10. The Role of Patients’ Age on Their Preferences for Choosing Additional Blood Pressure-Lowering Drugs: A Discrete Choice Experiment in Patients with Diabetes

    PubMed Central

    de Vries, Sieta T.; de Vries, Folgerdiena M.; Dekker, Thijs; Haaijer-Ruskamp, Flora M.; de Zeeuw, Dick; Ranchor, Adelita V.; Denig, Petra

    2015-01-01

    Objectives To assess whether patients’ willingness to add a blood pressure-lowering drug and the importance they attach to specific treatment characteristics differ among age groups in patients with type 2 diabetes. Materials and Methods Patients being prescribed at least an oral glucose-lowering and a blood pressure-lowering drug completed a questionnaire including a discrete choice experiment. This experiment contained choice sets with hypothetical blood pressure-lowering drugs and a no additional drug alternative, which differed in their characteristics (i.e. effects and intake moments). Differences in willingness to add a drug were compared between patients <75 years (non-aged) and ≥75 years (aged) using Pearson χ2-tests. Multinomial logit models were used to assess and compare the importance attached to the characteristics. Results Of the 161 patients who completed the questionnaire, 151 (72%) could be included in the analyses (mean age 68 years; 42% female). Aged patients were less willing to add a drug than non-aged patients (67% versus 84% respectively; P = 0.017). In both age groups, the effect on blood pressure was most important for choosing a drug, followed by the risk of adverse drug events and the risk of death. The effect on limitations due to stroke was only significant in the non-aged group. The effect on blood pressure was slightly more important in the non-aged than the aged group (P = 0.043). Conclusions Aged patients appear less willing to add a preventive drug than non-aged patients. The importance attached to various treatment characteristics does not seem to differ much among age groups. PMID:26445349

  11. Drop tube research

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1992-01-01

    This report covers the activities performed in the Drop Tube Study which The University of Alabama in Huntsville designed, fabricated and performed various low gravity experiments in materials processing from November 1, 1991 through October 30, 1992. During the performance of this contract the utilization of these ground-based containerless processing facilities has been instrumental in providing the opportunity to determine the feasibility of performing a number of solidification experiments in a simulated space environment, without the expense of a space-based experiment. A number of periodic reports have been given to the TCOR during the course of this contract hence this final report is meant only to summarize the many activities performed and not redundantly cover materials already submitted.

  12. Effects of the Dietary Addition of Amaranth (Amaranthus mantegazzianus) Protein Isolate on Antioxidant Status, Lipid Profiles and Blood Pressure of Rats.

    PubMed

    Lado, María B; Burini, Julieta; Rinaldi, Gustavo; Añón, María C; Tironi, Valeria A

    2015-12-01

    The effects of the dietary addition of 2.5% (w/w) Amaranthus mantegazzianus protein isolate (AI) on blood pressure, lipid profiles and antioxidative status of Wistar rats were evaluated. Six diets were used to feed animals during 28 days: (base (AIN93G), Chol (cholesterol 1%, w/w), CE (α-tocopherol 0.005%, w/w), CholE (cholesterol 1% (w/w) + α-tocopherol 0.005%, w/w), CAI (AI 2.5% w/w), CholAI (cholesterol 1% (w/w) + AI 2.5%, w/w). Lipid profiles of plasma and liver and faecal cholesterol content were analyzed. Antioxidant status was evaluated by the ferric reducing activity of plasma (FRAP), the 2-thiobarbituric acid (TBA) assay and superoxide dismutase (SOD) activity in plasma and liver. Blood pressure was measured in the tail artery of rats. CholA group presented a significant (α < 0.05) reduction (16%) in the plasma total cholesterol. In liver, the intake of cholesterol (Chol group) induced a significant increment in cholesterol and triglycerides (2.5 and 2.3 times, respectively), which could be decreased (18% and 47%, respectively) by the addition of AI (CholA group). This last group also showed an increased faecal cholesterol excretion (20%). Increment (50%) in FRAP values, diminution of TBA value in plasma and liver (70% and 38%, respectively) and diminution of SOD activity (20%) in plasma of CholA group suggest an antioxidant effect because of the intake of AI. In addition, CA and CholA groups presented a diminution (18%) of blood pressure after 28 days. PMID:26497504

  13. Do Bacterial Symbionts Govern Aphid's Dropping Behavior?

    PubMed

    Lavy, Omer; Sher, Noa; Malik, Assaf; Chiel, Elad

    2015-06-01

    Defensive symbiosis is amongst nature's most important interactions shaping the ecology and evolution of all partners involved. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbors one obligatory bacterial symbiont and up to seven different facultative symbionts, some of which are known to protect the aphid from pathogens, natural enemies, and other mortality factors. Pea aphids typically drop off the plant when a mammalian herbivore approaches it to avoid incidental predation. Here, we examined whether bacterial symbionts govern the pea aphid dropping behavior by comparing the bacterial fauna in dropping and nondropping aphids of two A. pisum populations, using two molecular techniques: high-throughput profiling of community structure using 16 S reads sequenced on the Illumina platform, and diagnostic polymerase chain reaction (PCR). We found that in addition to the obligatory symbiont, Buchnera aphidicola, the tested colonies of A. pisum harbored the facultative symbionts Serratia symbiotica, Regiella insecticola and Rickettsia, with no significant differences in infection proportions between dropping and nondropping aphids. While S. symbiotica was detected by both techniques, R. insecticola and Rickettsia could be detected only by diagnostic PCR. We therefore conclude that A. pisum's dropping behavior is not affected by its bacterial symbionts and is possibly affected by other factors. PMID:26313964

  14. First drop dissimilarity in drop-on-demand inkjet devices

    SciTech Connect

    Famili, Amin; Palkar, Saurabh A.; Baldy, William J. Jr.

    2011-01-15

    As inkjet printing technology is increasingly applied in a broader array of applications, careful characterization of its method of use is critical due to its inherent sensitivity. A common operational mode in inkjet technology known as drop-on-demand ejection is used as a way to deliver a controlled quantity of material to a precise location on a target. This method of operation allows ejection of individual or a sequence (burst) of drops based on a timed trigger event. This work presents an examination of sequences of drops as they are ejected, indicating a number of phenomena that must be considered when designing a drop-on-demand inkjet system. These phenomena appear to be driven by differences between the first ejected drop in a burst and those that follow it and result in a break-down of the linear relationship expected between driving amplitude and drop mass. This first drop, as quantified by high-speed videography and subsequent image analysis, can be different in morphology, trajectory, velocity, and volume from subsequent drops within a burst. These findings were confirmed orthogonally by both volume and mass measurement techniques which allowed quantitation down to single drops.

  15. Mixing in Sessile Drops Merging on a Surface

    NASA Astrophysics Data System (ADS)

    Anna, Shelley; Zhang, Ying; Oberdick, Samuel; Garoff, Stephen

    2011-11-01

    We investigate the mixing of two sessile drops that merge on a surface. The drops consist of low viscosity glycerol-water mixtures deposited on a silicone elastomer surface with contact angle near 90°. We observe the shape of the drops and the location of their intersection by placing a fluorescent dye in one drop and using a laser light sheet to image a plane perpendicular to the surface. The initial healing of the meniscus bridge between the merging drops, and the damping of capillary waves appearing on their surfaces occur on timescales comparable to the inertio-capillary relaxation time. However, the interface between the two fluids remains sharp, broadening diffusively over several minutes. The shape of the merged drops and the boundary between them also continues to evolve on a timescale of minutes. This later motion is controlled by gravity, capillary pressure, and viscous stresses. Images of the 3D drop shape indicate that small contact line motions are correlated to the slow relaxation. Although the two drops contain identical liquids except for the presence of the dye, the shape of the interface consistently evolves asymmetrically, assuming a characteristic crescent shape. We note that very tiny surface tension gradients can produce an asymmetric flow like the one observed here. We characterize the long timescale flow as a function of the drop sizes, and we use numerical simulations to aid in elucidating the essential physics.

  16. Identification of carbonates as additives in pressure-sensitive adhesive tape substrate with Fourier transform infrared spectroscopy (FTIR) and its application in three explosive cases.

    PubMed

    Lv, Jungang; Feng, Jimin; Zhang, Wen; Shi, Rongguang; Liu, Yong; Wang, Zhaohong; Zhao, Meng

    2013-01-01

    Pressure-sensitive tape is often used to bind explosive devices. It can become important trace evidence in many cases. Three types of calcium carbonate (heavy, light, and active CaCO(3)), which were widely used as additives in pressure-sensitive tape substrate, were analyzed with Fourier transform infrared spectroscopy (FTIR) in this study. A Spectrum GX 2000 system with a diamond anvil cell and a deuterated triglycine sulfate detector was employed for IR observation. Background was subtracted for every measurement, and triplicate tests were performed. Differences in positions of main peaks and the corresponding functional groups were investigated. Heavy CaCO(3) could be identified from the two absorptions near 873 and 855/cm, while light CaCO(3) only has one peak near 873/cm because of the low content of aragonite. Active CaCO(3) could be identified from the absorptions in the 2800-2900/cm region because of the existence of organic compounds. Tiny but indicative changes in the 878-853/cm region were found in the spectra of CaCO(3) with different content of aragonite and calcite. CaCO(3) in pressure-sensitive tape, which cannot be differentiated by scanning electron microscope/energy dispersive X-ray spectrometer and thermal analysis, can be easily identified using FTIR. The findings were successfully applied to three specific explosive cases and would be helpful in finding the possible source of explosive devices in future cases. PMID:22724657

  17. Large amplitude drop shape oscillations

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Wang, T. G.

    1982-01-01

    An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.

  18. The dropped big toe.

    PubMed

    Satku, K; Wee, J T; Kumar, V P; Ong, B; Pho, R W

    1992-03-01

    Surgical procedures for exposure of the upper third of the fibula have been known to cause weakness of the long extensor of the big toe post-operatively. The authors present three representative cases of surgically induced dropped big toe. From cadaveric dissection, an anatomic basis was found for this phenomenon. The tibialis anterior and extensor digitorum longus muscles have their origin at the proximal end of the leg and receive their first motor innervation from a branch that arises from the common peroneal or deep peroneal nerve at about the level of the neck of the fibula. However, the extensor hallucis longus muscle originates in the middle one-third of the leg and the nerves innervating this muscle run a long course in close proximity to the fibula for up to ten centimeters from a level below the neck of the fibula before entering the muscle. Surgical intervention in the proximal one-third of the fibula just distal to the origin of the first motor branch to the tibialis anterior and extensor digitorum longus muscles carries a risk of injury to the nerves innervating the extensor hallucis longus. PMID:1519891

  19. Simulations of Coulombic Fission of Charged Inviscid Drops

    NASA Astrophysics Data System (ADS)

    Burton, J. C.; Taborek, P.

    2011-04-01

    We present boundary-integral simulations of the evolution of critically charged droplets. For such droplets, small perturbations are unstable and eventually lead to the formation of a lemon-shaped drop with very sharp tips. For perfectly conducting drops, the tip forms a self-similar cone shape with a subtended angle identical to that of a Taylor cone, and quantities such as pressure and velocity diverge in time with power-law scaling. In contrast, when charge transport is described by a finite conductivity, we find that small progeny drops are formed at the tips, whose size decreases as the conductivity is increased. These small progeny drops are of nearly critical charge, and are precursors to the emission of a sustained flow of liquid from the tips as observed in experiments of isolated charged drops.

  20. Effect of neighboring perturbations on drop coalescence at an interface

    NASA Astrophysics Data System (ADS)

    Bordoloi, Ankur Deep; Longmire, Ellen K.

    2012-06-01

    Coalescence at a quiescent silicone oil/water glycerine interface was investigated for water/glycerine drops with Bond number ˜7 and Ohnesorge number = 0.01 using high-speed imaging and time-resolved tomographic particle image velocimetry. In addition to a single drop case, three perturbation cases were considered corresponding with a second drop, a solid particle wetted in oil, and a solid particle wetted in water/glycerine placed adjacent to the coalescing drop. Each perturbing object caused an initial tilting of the drop, influencing its rupture location and eventual collapse behavior. Once tilted, drops typically ruptured near their lowest vertical position which was located either toward or away from the perturbing object depending on the case. The initial retraction speed of the ruptured film was higher for drops initially tilted at significant angles, and the local variations in retraction speed correlated well with the expected variations in local film thickness. The drop fluid always collapsed away from the drop axis in the direction of the rupture location in all unperturbed or perturbed cases. In the case of a drop next to a particle wetted in water/glycerine, the collapsing fluid travelled away from the particle, and the downward propagating vortex ring which developed was similar to that resulting from an unperturbed drop rupture. By contrast, the drop fluid collapsed toward either a second drop or a particle wetted in oil. The resulting vortex rings were more asymmetric, and viscous interaction between the particle and collapsing fluid hindered the downward motion of the associated ring.

  1. Instrumented drop ball tester for percussion primers

    SciTech Connect

    Woods, C.M.; Robinson, M.A.; Merten, C.W.; Robbins, V.E. ); Begeal, D.R. )

    1991-01-01

    The drop ball tester has historically been used for determining the threshold characteristics of percussion primers. Typically, the data obtained from such a tester show a wide variation with significantly large standard deviations. This requires that the acceptance specifications for primers be fairly lax. To determine how much of the data scatter was due to the tester alone, a drop ball tester was instrumented with a force monitoring gage, velocity capabilities, deflection gages, and a pressure time output measuring system. This paper deals with the basic fundamental physics involved with the tester and presents results of improvements to the tester geometry. Threshold test results are presented, correlating all of the variables measured. 8 refs., 10 figs.

  2. A growing-drop technique for measuring dynamic interfacial tension

    SciTech Connect

    MacLeod, C.A.; Radke, C.J.

    1993-10-01

    A novel, growing-drop technique is described for measuring dynamic interfacial tension due to sorption of surface-active solutes. The proposed method relates the instantaneous pressure and size of expanding liquid drops to interfacial tension and is useful for measuring both liquid/gas and liquid/liquid tensions over a wide range of time scales, currently from 10 ms to several hours. Growing-drop measurements on surfactant-free water/air and water/octanol interfaces yield constant tensions equal to their known literature values. For surfactant-laden, liquid drops, the growing-drop technique captures the actual transient tension evolution of a single interface, rather than interval times as with the classic maximum-drop-pressure and drop.-volume tension measurements. Dynamic tensions measured for 0.25 mM aqueous 1-decanol solution/air and 0.02 kg/m{sup 3} aqueous Triton X-100 solution/dodecane interfaces show nonmonotonic behavior, indicating slow surfactant transport relative to the imposed rates of interfacial dilatation. The dynamic tension of a purified and fresh 6 mM aqueous sodium dodecyl sulfate (SDS) solution/air interface shows only a monotonic decrease, indicating rapid surfactant transport relative to the imposed rates of dilatation. ConverselY, an aged SDS solution, naturally containing trace dodecanol impurities, exhibits dynamic tensions which reflect a superposition of the rapidly equilibrating SDS and the slowly adsorbing dodecanol.

  3. Containerless protein crystal growth in rotating levitated drops

    NASA Astrophysics Data System (ADS)

    Chung, Sang K.; Trinh, Eugene H.

    1998-01-01

    A method for growing protein crystals in a containerless environment using an ultrasonic-electrostatic hybrid levitator is evaluated. In this approach, a single protein solution droplet bearing a surface charge is electrostatically levitated and acoustically rotated along a horizontal axis during the crystal nucleation and growth phases. Sample rotation is induced by ultrasonic streaming and radiation pressure applied in addition to the electrostatic levitation force. This unique approach is developed in order to create controlled crystal growth conditions which would reproduce some of the aspects of the low-gravity environment. We present the outcome of a development effort and feasibility study showing the successful growth of lysozyme and thaumatin crystals suspended within the bulk of quiescent liquid protein solutions inside rotating droplets also containing a very small concentration of agarose. Even though the crystals are not growing in a completely gelled medium and rotation is required for their long-term suspension, there are indications that a convectionless crystal growth environment has been obtained within the rotating drop, and that artificial flow can be introduced in a controlled manner by imposing drop shape oscillations.

  4. Theoretical Exploration of Barrel-Shaped Drops on Cactus Spines.

    PubMed

    Luo, Cheng

    2015-11-01

    To survive an arid environment, desert cacti are capable of harvesting water from fog by transporting condensed water drops using their spines. Cactus spines have a conical shape. In this work, on the basis of the difference of liquid pressure, a new theoretical model has been developed for a barrel-shaped liquid drop on a conical wire. This model is further simplified to interpret the effects of contact angles, conical angle, surface microgrooves, and gravity on the drop movement along a cactus spine. PMID:26473466

  5. Binary drop coalescence in liquids

    NASA Astrophysics Data System (ADS)

    Kim, Jungyong

    Experiments on binary drop collisions within an index-matched liquid were conducted for Weber numbers (We) of 1-50 and collision angles of 15-80° below the horizontal. Drop pairs of water/glycerin mixture were injected into silicone oil and, due to gravitational effects, traveled on downward trajectories before colliding. A dual-field high-speed PIV measurement system was employed to quantify drop trajectories and overall collision conditions while simultaneously examining detailed velocity fields near the collision interface. In the We range examined, for equal size drops, both rebounding and coalescing behavior occurred. The drops coalesced for We > 10 and rebounded for We < 10, and this boundary was found to be insensitive to collision angle. Coalescence was found to result from a combination of vortical flow within drops and strong drop deformation characteristic of higher We. Flow through the centers of opposing ring vortices, strengthened by drop deformation, enhanced drainage of the thin film in the impact region, leading to film rupture and coalescence. The collision angle affected the eventual location of film rupture, with the rupture location moving higher in the thin film region as the collision angle increased. The film rupture location correlated closely with the location of maximum downward velocity in the thin film. The time between collision and rupture increases with We until We = 30. For We > 30, the time decreases as We increases. Unequal size drop collisions with drop size ratios (Ds/D L) of 0.7 and 0.5 were also examined. Coalescence occurs above We* = 11 similar to equal size drops. As drop size ratio decreases, the intervening film deforms more. If the velocity ratio uL/u s < 1, the deformed interface becomes flat before coalescence. The rupture location varies due to the asymmetry of the drops. As collision offset increases (B > 0), the film rupture time is shortened and mixing of the fluid from both drops is enhanced after coalescence

  6. Magnetic control of Leidenfrost drops.

    PubMed

    Piroird, Keyvan; Clanet, Christophe; Quéré, David

    2012-05-01

    We show how a magnetic field can influence the motion of a paramagnetic drop made of liquid oxygen in a Leidenfrost state on solids at room temperature. It is demonstrated that the trajectory can be modified in both direction and velocity and that the results can be interpreted in terms of classical mechanics as long as the drop does not get too close to the magnet. We study the deviation and report that it can easily overcome 180∘ and even diverge under certain conditions, leading to situations where a drop gets captured. In the vicinity of the magnet, another type of trapping is observed, due to the deformation of the drop in this region, which leads to a strong energy dissipation. Conversely, drops can be accelerated by moving magnets (slingshot effect). PMID:23004866

  7. Observation of ice nucleation in acoustically levitated water drops

    NASA Astrophysics Data System (ADS)

    Lü, Y. J.; Xie, W. J.; Wei, B.

    2005-10-01

    The supercooling and nucleation of acoustically levitated water drops were investigated at two different sound pressure levels (SPL). These water drops were supercooled by 13to16K at the low SPL of 160.6dB, whereas their supercoolings varied from 5to11K at the high SPL of 164.4dB. The maximum supercooling obtained in the experiments is 32K. Statistical analyses based on the classical nucleation theory reveal that the occurrence of ice nucleation in water drops is mainly confined to the surface region under acoustic levitation conditions and the enlargement of drop surface area caused by the acoustic radiation pressure reduces water supercoolability remarkably. A comparison of the nucleation rates at the two SPLs indicates that the sound pressure can strengthen the surface-dominated nucleation of water drops. The acoustic stream around levitated water drops and the cavitation effect associated with ultrasonic field are the main factors that induce surface-dominated nucleation.

  8. Combination therapy of angiotensin II receptor blocker and calcium channel blocker exerts pleiotropic therapeutic effects in addition to blood pressure lowering: amlodipine and candesartan trial in Yokohama (ACTY).

    PubMed

    Maeda, Akinobu; Tamura, Kouichi; Kanaoka, Tomohiko; Ohsawa, Masato; Haku, Sona; Azushima, Kengo; Dejima, Toru; Wakui, Hiromichi; Yanagi, Mai; Okano, Yasuko; Fujikawa, Tetsuya; Toya, Yoshiyuki; Mizushima, Shunsaku; Tochikubo, Osamu; Umemura, Satoshi

    2012-01-01

    Recent guidelines recommend combination antihypertensive therapy to achieve the target blood pressure (BP) and to suppress target organ damage. This study aimed to examine the beneficial effects of combination therapy with candesartan and amlodipine on BP control and markers of target organ function in Japanese essential hypertensive patients (N = 20) who did not achieve the target BP level during the monotherapy period with either candesartan or amlodipine. After the monotherapy period, for patients already being treated with amlodipine, a once-daily 8 mg dose of candesartan was added on during the combination therapy period (angiotensin II receptor blocker [ARB] add-on group, N = 10), and a once-daily 5 mg dose of amlodipine was added on for those already being treated with candesartan (calcium channel blocker [CCB] add-on group, N = 10). Combination therapy with candesartan and amlodipine for 12 weeks significantly decreased clinic and home systolic blood pressure (SBP) and diastolic blood pressure (DBP). In addition, the combination therapy was able to significantly reduce urine albumin excretion without decrease in estimated glomerular filtration ratio and resulted in significant improvements in brachial-ankle pulse wave velocity, central SBP, and insulin sensitivity. Furthermore, the CCB add-on group showed a significantly greater decrease in clinic and home DBP than the ARB add-on group. The calcium channel blocker add-on group also exhibited better improvements in vascular functional parameters than the ARB add-on group. These results suggest that combination therapy with candesartan and amlodipine is an efficient therapeutic strategy for hypertension with pleiotropic benefits. PMID:22571446

  9. Axisymmetric model of drop spreading on a horizontal surface

    NASA Astrophysics Data System (ADS)

    Mistry, Aashutosh; Muralidhar, K.

    2015-09-01

    Spreading of an initially spherical liquid drop over a textured surface is analyzed by solving an integral form of the governing equations. The mathematical model extends Navier-Stokes equations by including surface tension at the gas-liquid boundary and a force distribution at the three phase contact line. While interfacial tension scales with drop curvature, the motion of the contact line depends on the departure of instantaneous contact angle from its equilibrium value. The numerical solution is obtained by discretizing the spreading drop into disk elements. The Bond number range considered is 0.01-1. Results obtained for sessile drops are in conformity with limiting cases reported in the literature [J. C. Bird et al., "Short-time dynamics of partial wetting," Phys. Rev. Lett. 100, 234501 (2008)]. They further reveal multiple time scales that are reported in experiments [K. G. Winkels et al., "Initial spreading of low-viscosity drops on partially wetting surfaces," Phys. Rev. E 85, 055301 (2012) and A. Eddi et al., "Short time dynamics of viscous drop spreading," Phys. Fluids 25, 013102 (2013)]. Spreading of water and glycerin drops over fully and partially wetting surfaces is studied in terms of excess pressure, wall shear stress, and the dimensions of the footprint. Contact line motion is seen to be correctly captured in the simulations. Water drops show oscillations during spreading while glycerin spreads uniformly over the surface.

  10. The origin of star-shaped oscillations of Leidenfrost drops

    NASA Astrophysics Data System (ADS)

    Ma, Xiaolei; Burton, Justin C.

    We experimentally investigate the oscillations of Leidenfrost drops of water, liquid nitrogen, ethanol, methanol, acetone and isopropyl alcohol. The drops levitate on a cushion of evaporated vapor over a hot, curved surface which keeps the drops stationary. We observe star-shaped modes along the periphery of the drop, with mode numbers n = 2 to 13. The number of observed modes is sensitive to the properties of the liquid. The pressure oscillation frequency in the vapor layer under the drop is approximately twice that of the drop frequency, which is consistent with a parametric forcing mechanism. However, the Rayleigh and thermal Marangoni numbers are of order 10,000, indicating that convection should play a dominating role as well. Surprisingly, we find that the wavelength and frequency of the oscillations only depend on the thickness of the liquid, which is twice the capillary length, and do not depend on the mode number, substrate temperature, or the substrate curvature. This robust behavior suggests that the wavelength for the oscillations is set by thermal convection inside the drop, and is less dependent on the flow in the vapor layer under the drop

  11. A new method for measuring the dynamic surface tension of complex-mixture liquid drops

    SciTech Connect

    Zhang, X.; Harris, M.T.; Basaran, O.A.

    1994-06-29

    A simple and accurate technique has been developed for measuring dynamic surface tension. The new technique is based on growing a drop at the end of a fine capillary into another immiscible fluid and can follow the changes in tension at a freshly formed interface during its entire period of evolution. When the relative importance of the surface tension force is large compared to gravitational and viscous forces, shapes of growing drops are sections of spheres and the difference in pressure between the interior and the exterior of the drop {triangle}p is related to the surface tension {sigma} and the radius of curvature R by the static Young-Laplace formula {triangle}p = 2{sigma}/R. In contrast to related work, the new technique can determine the surface tension of an interface with a surface age of a few to tens of milliseconds by measuring transient drop shapes and pressures in 1/6 to 1 millisecond. The capabilities of the new method are demonstrated by performing tension measurements on liquid systems that do not exhibit dynamic surface tension as well as ones that exhibit significant dynamic tension effects. Tension measurements made with surfactant-laden solutions show that variation of surface tension is nonmonotonic in time. In such systems, the dynamic behavior of surface tension is shown to depend upon both the rate of interfacial dilatation and that of surfactant transport. A maximum in the surface tension is attained when the lowering of the surfactant concentration on the drop interface due to its dilatation is balanced by the addition of fresh surfactant to the interface by convection and diffusion.

  12. Effect of high-pressure/temperature (HP/T) treatments of in-package food on additive migration from conventional and bio-sourced materials.

    PubMed

    Mauricio-Iglesias, M; Jansana, S; Peyron, S; Gontard, N; Guillard, V

    2010-01-01

    Migration was assessed during and after two high-pressure/temperature (HP/T) treatments intended for a pasteurization (800 MPa for 5 min, from 20 to 40 degrees C) and a sterilization treatment (800 MPa for 5 min, from 90 to 115 degrees C) and were compared with conventional pasteurization and sterilization, respectively. The specific migration of actual packaging additives used as antioxidants and ultraviolet light absorbers (Irganox 1076, Uvitex OB) was investigated in a number of food-packaging systems combining one synthetic common packaging (LLDPE) and a bio-sourced one (PLA) in contact with the four food-simulating liquids defined by European Commission regulations. After standard HP/T processing, migration kinetics was followed during the service life of the packaging material using Fourier transform infrared spectrometer (FTIR) spectroscopy. LLDPE withstood the high-pressure sterilization, whereas it melted during the conventional sterilization. No difference was observed on migration from LLDPE for both treatments. In the case of PLA, migration of Uvitex OB was very low or not detectable for all the cases studied. PMID:19809898

  13. Polymerized complex synthesis of a pure 93 K Y2Ba4Cu7O(15-d) superconductor without the need of high oxygen pressure and additive catalysts

    NASA Astrophysics Data System (ADS)

    Berastegui, Pedro; Kakihana, Masato; Yoshimura, Masahiro; Mazaki, Hiromasa; Yasuoka, Hiroshi; Johansson, Lars-Gunnar; Eriksson, Sten; Borjesson, Lars; Kall, Mikael

    1993-03-01

    High-purity ceramic material of the superconducting phase Y2Ba4Cu7O(14.82) (247) has been synthesized at 870 C by the polymerized complex method using neither high oxygen pressure nor additive catalysts. The method is based on the formation of a polymer-metal complex precursor which is prepared through polyesterification between metal citrate complexes and ethylene glycol. Apart from obviating high oxygen pressure, the present preparation technique offers easier fabrication of highly pure 247 material compared with other 'wet' chemical routes, since it eliminates many steps (centrifugation, filtration, aging, and pH control). XRD and Raman scattering analyses show that the material is single-phase without any indication of secondary phases. Zero-resistance has been achieved at 88.0 K with a transition width narrower than 4 K. Complex ac magnetic susceptibility measurements confirm the presence of a single bulk superconducting 247 phase with Tc (onset) = 93.0 K and Delta-Tc (10-90 percent) = 4.5 K.

  14. Simulations of Evaporating Multicomponent Fuel Drops

    NASA Technical Reports Server (NTRS)

    Bellan, Josette; Le Clercq, Patrick

    2005-01-01

    A paper presents additional information on the subject matter of Model of Mixing Layer With Multicomponent Evaporating Drops (NPO-30505), NASA Tech Briefs, Vol. 28, No. 3 (March 2004), page 55. To recapitulate: A mathematical model of a three-dimensional mixing layer laden with evaporating fuel drops composed of many chemical species has been derived. The model is used to perform direct numerical simulations in continuing studies directed toward understanding the behaviors of sprays of liquid petroleum fuels in furnaces, industrial combustors, and engines. The model includes governing equations formulated in an Eulerian and a Lagrangian reference frame for the gas and drops, respectively, and incorporates a concept of continuous thermodynamics, according to which the chemical composition of a fuel is described by use of a distribution function. In this investigation, the distribution function depends solely on the species molar weight. The present paper reiterates the description of the model and discusses further in-depth analysis of the previous results as well as results of additional numerical simulations assessing the effect of the mass loading. The paper reiterates the conclusions reported in the cited previous article, and states some new conclusions. Some new conclusions are: 1. The slower evaporation and the evaporation/ condensation process for multicomponent-fuel drops resulted in a reduced drop-size polydispersity compared to their single-component counterpart. 2. The inhomogeneity in the spatial distribution of the species in the layer increases with the initial mass loading. 3. As evaporation becomes faster, the assumed invariant form of the molecular- weight distribution during evaporation becomes inaccurate.

  15. Nonlinear Bubble Interactions in Acoustic Pressure Fields

    NASA Technical Reports Server (NTRS)

    Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi

    1996-01-01

    The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).

  16. Ground Motion Prediction Equations Empowered by Stress Drop Measurement

    NASA Astrophysics Data System (ADS)

    Miyake, H.; Oth, A.

    2015-12-01

    Significant variation of stress drop is a crucial issue for ground motion prediction equations and probabilistic seismic hazard assessment, since only a few ground motion prediction equations take into account stress drop. In addition to average and sigma studies of stress drop and ground motion prediction equations (e.g., Cotton et al., 2013; Baltay and Hanks, 2014), we explore 1-to-1 relationship for each earthquake between stress drop and between-event residual of a ground motion prediction equation. We used the stress drop dataset of Oth (2013) for Japanese crustal earthquakes ranging 0.1 to 100 MPa and K-NET/KiK-net ground motion dataset against for several ground motion prediction equations with volcanic front treatment. Between-event residuals for ground accelerations and velocities are generally coincident with stress drop, as investigated by seismic intensity measures of Oth et al. (2015). Moreover, we found faster attenuation of ground acceleration and velocities for large stress drop events for the similar fault distance range and focal depth. It may suggest an alternative parameterization of stress drop to control attenuation distance rate for ground motion prediction equations. We also investigate 1-to-1 relationship and sigma for regional/national-scale stress drop variation and current national-scale ground motion equations.

  17. Drop impact and rebound dynamics on an inclined superhydrophobic surface.

    PubMed

    Yeong, Yong Han; Burton, James; Loth, Eric; Bayer, Ilker S

    2014-10-14

    Due to its potential in water-repelling applications, the impact and rebound dynamics of a water drop impinging perpendicular to a horizontal superhydrophobic surface have undergone extensive study. However, drops tend to strike a surface at an angle in applications. In such cases, the physics governing the effects of oblique impact are not well studied or understood. Therefore, the objective of this study was to conduct an experiment to investigate the impact and rebound dynamics of a drop at various liquid viscosities, in an isothermal environment, and on a nanocomposite superhydrophobic surface at normal and oblique impact conditions (tilted at 15°, 30°, 45°, and 60°). This study considered drops falling from various heights to create normal impact Weber numbers ranging from 6 to 110. In addition, drop viscosity was varied by decreasing the temperature for water drops and by utilizing water-glycerol mixtures, which have similar surface tension to water but higher viscosities. Results revealed that oblique and normal drop impact behaved similarly (in terms of maximum drop spread as well as rebound dynamics) at low normal Weber numbers. However, at higher Weber numbers, normal and oblique impact results diverged in terms of maximum spread, which could be related to asymmetry and more complex outcomes. These asymmetry effects became more pronounced as the inclination angle increased, to the point where they dominated the drop impact and rebound characteristics when the surface was inclined at 60°. The drop rebound characteristics on inclined surfaces could be classified into eight different outcomes driven primarily by normal Weber number and drop Ohnesorge numbers. However, it was found that these outcomes were also a function of the receding contact angle, whereby reduced receding angles yielded tail-like structures. Nevertheless, the contact times of the drops with the coating were found to be generally independent of surface inclination. PMID:25216298

  18. Instant freezing of impacting wax drops

    NASA Astrophysics Data System (ADS)

    Ponomarenko, Alexandre; Virot, Emmanuel; Rubinstein, Shmuel

    2015-11-01

    We present the impact of hot liquid drops of wax on surfaces whose temperature is below the solidifying temperature of the drops. During the fall the drops remain mostly liquid, but upon impact, their temperature quickly decreases resulting in the solidification of the drop. Depending on the impact energy, drops size and the temperature difference between the drop and the surface this results in plethora of solid shapes: simple lenses, triangular drops, spherical caps and popped popcorn shapes.

  19. Electrokinetics of isolated electrified drops.

    PubMed

    Pillai, Rohit; Berry, Joseph D; Harvie, Dalton J E; Davidson, Malcolm R

    2016-04-14

    Using a recently developed multiphase electrokinetic model, we simulate the transient electrohydrodynamic response of a liquid drop containing ions, to both small and large values of electric field. The temporal evolution is found to be governed primarily by two dimensionless groups: (i) Ohnesorge number (Oh), a ratio of viscous to inertio-capillary effects, and (ii) inverse dimensionless Debye length (κ), a measure of the diffuse regions of charge that develop in the drop. The effects of dielectric polarization dominate at low Oh, while effects of separated charge gain importance with increase in Oh. For small values of electric field, the deformation behaviour of a drop is shown to be accurately described by a simple analytical expression. At large electric fields, the drops are unstable and eject progeny drops. Depending on Oh and κ this occurs via dripping or jetting; the regime transitions are shown by a Oh-κ phase map. In contrast to previous studies, we find universal scaling relations to predict size and charge of progeny drops. Our simulations suggest charge transport plays a significant role in drop dynamics for 0.1 ≤ Oh ≤ 10, a parameter range of interest in microscale flows. PMID:26954299

  20. Pool impacts of Leidenfrost drop

    NASA Astrophysics Data System (ADS)

    Darbois Texier, Baptiste; Maquet, Laurent; Dorbolo, Stephane; Dehandschoewercker, Eline; Pan, Zhao; Truscott, Tadd

    2015-11-01

    This work concerns the impact of a droplet made of a volatile liquid (typically HFE) on a pool of an other liquid (typically silicone oil) which temperature is above the boiling point of the drop. Depending on the properties of the two liquids and the impacting conditions, four different regimes are observed. For low impacting speeds, the droplet bounces on the surface of the bath and finally levitates above it in a Leidenfrost state. Such a regime occurs as soon as the pool temperature exceeds the boiling point of the drop. This observation means that there is no threshold in temperature for a Leidenfrost effect on a liquid surface contrary to the case of a solid substrate. For intermediate impacting velocities, the pinch-off of the surface of the pool entraps the drop in the liquid bulk. The entrapped drop is separated from the pool by a layer of its own vapour in a similar way of antibulles. For increasing impacting speeds, the vapour layer between the drop and the pool does not hold during the pinch-off event. The contact of the drop with the hot liquid provokes a sudden and intense evaporation. At very large impacting speeds, the drop rapidely contacts the pool, spreads and finally induces a hemi-spherical cavity. In the end, these four different regimes are summarized in a Froud-Weber diagram which boundaries are discussed.

  1. [Development of intranasal lactocin (oxytocin) drops technology].

    PubMed

    Klimas, Rimantas; Baranauskas, Algirdas; Gendrolis, Antanas

    2002-01-01

    Pure oxytocin substance was obtained from posterior part of cattle pituitary gland by high pressure liquid chromatography. Biological activity of the substance--450-500 IU/mg. Chromatographically pure Oxytocin substance was used in developing two different compositions of Lactocin intranasal drops (40 IU/ml). Stability evaluation was performed for 2 year period. The technical documentation was prepared on the basis of the research results. Lactocin is active preparation helping lactation and is indicated for lactostasis treatment and its prophylaxis after delivery. PMID:12474675

  2. Effects of Lower-Leg Kinesiology Taping on Balance Ability in Stroke Patients with Foot Drop

    PubMed Central

    Bae, Young-Hyeon; Kim, Hyeong Geun; Min, Kyung Sam; Lee, Suk Min

    2015-01-01

    Objective. The purpose of this study was to observe the effects of lower-leg kinesiology taping on balance ability in stroke patients with foot drop. Design. Randomized controlled trial study. Method. Thirty stroke patients with foot drop were randomly divided into two groups. The experimental group underwent kinesiology taping, and the control group underwent placebo taping. Balance ability was assessed before and after taping in both groups. Results. No difference was observed over time in the Berg Balance Scale score between the two groups, and a significant difference in the Berg Balance Scale score was observed only in the experimental group. Additionally, there were significant differences in the center of pressure area and limits of stability over time. Conclusion. Kinesiology taping temporarily improved static balance ability in stroke patients. However, its effect on dynamic balance was not verified. Therefore, further research on the influence of long-term kinesiology taping on dynamic balance and gait ability is suggested. PMID:26579200

  3. Pressure Profiles in a Loop Heat Pipe Under Gravity Influence

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2015-01-01

    During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

  4. Pressure Profiles in a Loop Heat Pipe under Gravity Influence

    NASA Technical Reports Server (NTRS)

    Ku, Jentung

    2015-01-01

    During the operation of a loop heat pipe (LHP), the viscous flow induces pressure drops in various elements of the loop. The total pressure drop is equal to the sum of pressure drops in vapor grooves, vapor line, condenser, liquid line and primary wick, and is sustained by menisci at liquid and vapor interfaces on the outer surface of the primary wick in the evaporator. The menisci will curve naturally so that the resulting capillary pressure matches the total pressure drop. In ground testing, an additional gravitational pressure head may be present and must be included in the total pressure drop when LHP components are placed in a non-planar configuration. Under gravity-neutral and anti-gravity conditions, the fluid circulation in the LHP is driven solely by the capillary force. With gravity assist, however, the flow circulation can be driven by the combination of capillary and gravitational forces, or by the gravitational force alone. For a gravity-assist LHP at a given elevation between the horizontal condenser and evaporator, there exists a threshold heat load below which the LHP operation is gravity driven and above which the LHP operation is capillary force and gravity co-driven. The gravitational pressure head can have profound effects on the LHP operation, and such effects depend on the elevation, evaporator heat load, and condenser sink temperature. This paper presents a theoretical study on LHP operations under gravity-neutral, anti-gravity, and gravity-assist modes using pressure diagrams to help understand the underlying physical processes. Effects of the condenser configuration on the gravitational pressure head and LHP operation are also discussed.

  5. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    PubMed Central

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-01-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning. PMID:27406904

  6. Influence of Metal Diboride and Dy2O3 Additions on Microstructure and Properties of MgB2 Fabricated at High Temperatures and under Pressure

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Sumption, M. D.; Collings, E. W.

    2016-07-01

    High temperatures and under pressure (HTP) processing has been used to study the effects of chemical doping in MgB2. ZrB2, TiB2 and NbB2 were selected as additives since, like MgB2, they have an AlB2-type structure and similar lattice parameters. Dy2O3 was selected as it has been reported to generate nanoscale, secondary intragrain phases in MgB2. While C is known to enter the B-sublattice readily, attempts to dope Zr and other elements onto the Mg site have been less successful due to slow bulk diffusion, low solubility in MgB2, or both. We have used high-temperature, solid-state sintering (1500 °C), as well as excursions through the peritectic temperature (up to 1700 °C), to investigate both of these limitations. Bulk MgB2 samples doped with MB2 (M = Zr, Ti and Nb) and Dy2O3 additions were synthesized and then characterized. Lattice distortion and high densities of crystal defects were observed in the MgB2 grains around nano-sized MB2 inclusions, this highly defected band contributed to a large increase in Bc2 but was not large enough to increase the irreversibility field. In contrast, distributed intragrain precipitates were formed by Dy2O3 additions which did not change the lattice parameters, Tc, Tc distribution or Bc2 of MgB2, but modified the flux pinning.

  7. Leidenfrost drops: Effect of gravity

    NASA Astrophysics Data System (ADS)

    Maquet, L.; Brandenbourger, M.; Sobac, B.; Biance, A.-L.; Colinet, P.; Dorbolo, S.

    2015-04-01

    A specific experimental set-up has been installed in a large centrifuge facility in order to study different aspects of Leidenfrost drops under high-gravity conditions (5, 10, 15 and 20 times the Earth gravity). In particular, the drop lifetime and more precisely the variations of drop diameter vs. time have shown to be in good agreement with previous experiments and scaling analysis (Biance A.-L. et al., Phys. Fluids, 15 (2003) 1632). Moreover, so-called chimneys are expectedly observed in the large puddles, the distance between two chimneys depending linearly on the capillary length. Finally, the Leidenfrost point, i.e. the temperature above which the Leidenfrost effect takes place, was unexpectedly found to increase slightly with gravity. A qualitative explanation based on a refined model (Sobac B. et al., Phys. Rev. E, 90 (2014) 053011) recognizing the non-trivial shape of the vapor film under the drop is proposed to explain this observation.

  8. Orion Capsule Mockup is Dropped

    NASA Video Gallery

    An Orion capsule mockup is dropped from a plane 25,000 feet above the Arizona desert to test its parachute design. Orion will return to Earth at speeds faster than previous human spacecraft, and wi...

  9. Analysis of the convective evaporation of nondilute clusters of drops

    NASA Technical Reports Server (NTRS)

    Bellan, J.; Harstad, K.

    1987-01-01

    The penetration distance of an outer flow into a drop cluster volume is the critical, evaporation mode-controlling parameter in the present model for nondilute drop clusters' convective evaporation. The model is found to perform well for such low penetration distances as those obtained for dense clusters in hot environments and low relative velocities between the outer gases and the cluster. For large penetration distances, however, the predictive power of the model deteriorates; in addition, the evaporation time is found to be a weak function of the initial relative velocity and a strong function of the initial drop temperature. The results generally show that the interior drop temperature was transient throughout the drop lifetime, although temperature nonuniformities persisted up to the first third of the total evaporation time at most.

  10. Capillary-inertial colloidal catapults upon drop coalescence

    NASA Astrophysics Data System (ADS)

    Chavez, Roger L.; Liu, Fangjie; Feng, James J.; Chen, Chuan-Hua

    2016-07-01

    Surface energy released upon drop coalescence is known to power the self-propelled jumping of liquid droplets on superhydrophobic solid surfaces, and the jumping droplets can additionally carry colloidal payloads toward self-cleaning. Here, we show that drop coalescence on a spherical particle leads to self-propelled launching of the particle from virtually any solid surface. The main prerequisite is an intermediate wettability of the particle, such that the momentum from the capillary-inertial drop coalescence process can be transferred to the particle. By momentum conservation, the launching velocity of the particle-drop complex is proportional to the capillary-inertial velocity based on the drop radius and to the fraction of the liquid mass in the total mass. The capillary-inertial catapult is not only an alternative mechanism for removing colloidal contaminants, but also a useful model system for studying ballistospore launching.

  11. Thermally driven oscillations and wave motion of a liquid drop

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Hendricks, R. C.; Schoessow, G. J.

    1977-01-01

    In the state of Leidenfrost boiling, liquid drops are observed to vibrate in a variety of modal patterns. Theories are presented which predict the frequency of oscillation and show that the observed modal patterns of drops correspond to the minimum energy oscillatory excitation state. High-speed photographic techniques were used to record these motions and substantiate the theories. An incipient temperature was also found for water drops in film boiling below which free oscillations do not exist. In addition to these oscillations, photographic sequences are presented which show that wave motion can exist along the circumference of the drop. Following the study of free oscillations, the system was mounted on a shaker table and the drop subjected to a range of forced frequencies and accelerations.

  12. Coalescence of Drops of a Power-law Fluid

    NASA Astrophysics Data System (ADS)

    Kamat, Pritish; Thete, Sumeet; Basaran, Osman

    2014-11-01

    Drop coalescence is crucial in a host of industrial, household, and natural processes that involve dispersions. Coalescence is a rate-controlling process in breaking emulsions and strongly influences drop-size-distributions in sprays. In a continuum approach, coalescence begins by the formation of a microscopic, non-slender bridge connecting the two drops. Indefinitely large axial curvature at the neck results in local lowering of pressure that drives fluid from the bulk of the drops toward the neck, thereby causing the bridge radius r (t) and height z (t) to increase in time t. The coalescence of Newtonian drops in air has heretofore been thoroughly studied. Here, we extend these earlier studies by analyzing the coalescence of drops of power-law fluids because many fluids encountered in real applications, including cosmetic creams, shampoos, grease, and paint, exhibit power-law (deformation-rate thinning) rheology. On account of the non-slender geometry of the liquid bridge connecting the two drops (z << r) , we analyze the resulting free surface flow problem by numerical simulation. Among other results, we present and discuss the nature of flows and scaling behaviors for r and z as functions of the initial viscosity and power-law index (0 < n <= 1) .

  13. Control of Drop Motion by Mechanical Vibrations

    NASA Astrophysics Data System (ADS)

    Bestehorn, Michael

    2014-11-01

    Since the first experimental observations of Michael Faraday in 1831 it is known that a vibrating liquid may show an instability of its flat free surface with respect to oscillating regular surface patterns. We study thin liquid films on a horizontal substrate in the long wave approximation. The films are parametrically excited by mechanical horizontal or inclined oscillations. Inertia effects are taken into account and the standard thin film formulation is extended by a second equation for the vertically averaged mass flux. The films can be additionally unstable by Van der Waals forces on a partially wetting substrate, leading to the formation of drops. These drops can be manipulated by the vibrations to move in a desired direction. Linear results based on a damped complex valued Mathieu equation as well as fully nonlinear results using a reduced model will be presented, for more details see.

  14. Electrostatic Liquid-Drop-Levitation System

    NASA Technical Reports Server (NTRS)

    Rhim, Won Kyu; Chung, San Kun; Hyson, Michael T.; Elleman, Daniel D.

    1988-01-01

    Electrostatic levitator has levitated drops of liquid up to 4 mm in diameter while maintaining spherical drop shapes. Stable levitation of spherical drops valuable in experiments involving super-cooling, solidification, and crystal growth.

  15. Static shape and instability of an acoustically levitated liquid drop

    NASA Astrophysics Data System (ADS)

    Lee, C. P.; Anilkumar, A. V.; Wang, T. G.

    1991-11-01

    There have been observations that an intense sound field can break up a liquid drop in levitation by flattening it drastically through radiation pressure. Using high-speed photography, it is observed that, for a low-viscosity liquid, at a high sound intensity, ripples appear on the central membrane of the drop. At a higher intensity, the membrane may atomize by emitting satellite drops from its unstable ripples. For a general viscosity, it might also buckle upward like an umbrella and shatter, or might simply expand horizontally like a sheet and shatter. Using a disklike model for the flattened drop, the phenomenon was studied and good qualitative agreement with the observations was found. It is believed that at low viscosity, the ripples are capillary waves generated by the parametric instability excited by the membrane vibration, which is driven by the sound pressure. Atomization occurs whenever the membrane becomes so thin that the vibration is sufficiently intense. For any viscosity, the vibration leads to a Bernoulli correction in the static pressure, which is destabilizing. Buckling occurs when an existent equilibrium is unstable to a radial oscillation of the membrane because of the Bernoulli effect. Besides, the radiation stress at the rim of the flattened drop, being a suction stress, is also destabilizing, leading to the horizontal expansion and the subsequent breakup.

  16. Bioinspired tilt-angle fabricated structure gradient fibers: micro-drops fast transport in a long-distance

    NASA Astrophysics Data System (ADS)

    Chen, Yuan; Wang, Lin; Xue, Yan; Jiang, Lei; Zheng, Yongmei

    2013-10-01

    Issues of surfaces, e.g., inspired from beetle's back, spider silk, cactus stem, etc., become the active area of research on designing novel materials in need of human beings to acquire fresh water resource from air. However, the design of materials on surface structure is little achieved on controlling of micro-scale drop transport in a long distance. Here, we report the ability of micro-drop transport in a long distance on a bioinspired Fibers with Gradient Spindle-knots (BFGS), which are fabricated by tilt angle dip-coating method. The micro-drop of ~0.25 μL transports in distance of ~5.00 mm, with velocity of 0.10-0.22 m s-1 on BFGS. It is attributed to the multi-level cooperation of the release energy of drop coalescence along the gradient spindle-knots, in addition to capillary adhesion force and continuous difference of Laplace pressure, accordingly, water drops are driven to move fast directionally in a long distance on BFGS.

  17. Bioinspired tilt-angle fabricated structure gradient fibers: micro-drops fast transport in a long-distance.

    PubMed

    Chen, Yuan; Wang, Lin; Xue, Yan; Jiang, Lei; Zheng, Yongmei

    2013-01-01

    Issues of surfaces, e.g., inspired from beetle's back, spider silk, cactus stem, etc., become the active area of research on designing novel materials in need of human beings to acquire fresh water resource from air. However, the design of materials on surface structure is little achieved on controlling of micro-scale drop transport in a long distance. Here, we report the ability of micro-drop transport in a long distance on a bioinspired Fibers with Gradient Spindle-knots (BFGS), which are fabricated by tilt angle dip-coating method. The micro-drop of ~0.25 μL transports in distance of ~5.00 mm, with velocity of 0.10-0.22 m s⁻¹ on BFGS. It is attributed to the multi-level cooperation of the release energy of drop coalescence along the gradient spindle-knots, in addition to capillary adhesion force and continuous difference of Laplace pressure, accordingly, water drops are driven to move fast directionally in a long distance on BFGS. PMID:24113433

  18. Nonlinear dynamics of drops and bubbles and chaotic phenomena

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene H.; Leal, L. G.; Feng, Z. C.; Holt, R. G.

    1994-01-01

    Nonlinear phenomena associated with the dynamics of free drops and bubbles are investigated analytically, numerically and experimentally. Although newly developed levitation and measurement techniques have been implemented, the full experimental validation of theoretical predictions has been hindered by interfering artifacts associated with levitation in the Earth gravitational field. The low gravity environment of orbital space flight has been shown to provide a more quiescent environment which can be utilized to better match the idealized theoretical conditions. The research effort described in this paper is a closely coupled collaboration between predictive and guiding theoretical activities and a unique experimental program involving the ultrasonic and electrostatic levitation of single droplets and bubbles. The goal is to develop and to validate methods based on nonlinear dynamics for the understanding of the large amplitude oscillatory response of single drops and bubbles to both isotropic and asymmetric pressure stimuli. The first specific area on interest has been the resonant coupling between volume and shape oscillatory modes isolated gas or vapor bubbles in a liquid host. The result of multiple time-scale asymptotic treatment, combined with domain perturbation and bifurcation methods, has been the prediction of resonant and near-resonant coupling between volume and shape modes leading to stable as well as chaotic oscillations. Experimental investigations of the large amplitude shape oscillation modes of centimeter-size single bubbles trapped in water at 1 G and under reduced hydrostatic pressure, have suggested the possibility of a low gravity experiment to study the direct coupling between these low frequency shape modes and the volume pulsation, sound-radiating mode. The second subject of interest has involved numerical modeling, using the boundary integral method, of the large amplitude shape oscillations of charged and uncharged drops in the presence

  19. Forced Oscillations of Supported Drops

    NASA Technical Reports Server (NTRS)

    Wilkes, Edward D.; Basaran, Osman A.

    1996-01-01

    Oscillations of supported liquid drops are the subject of wide scientific interest, with applications in areas as diverse as liquid-liquid extraction, synthesis of ceramic powders, growing of pure crystals in low gravity, and measurement of dynamic surface tension. In this research, axisymmetric forced oscillations of arbitrary amplitude of viscous liquid drops of fixed volume which are pendant from or sessile on a rod with a fixed or moving contact line and surrounded by an inviscid ambient gas are induced by moving the rod in the vertical direction sinusiodally in time. In this paper, a preliminary report is made on the computational analysis of the oscillations of supported drops that have 'clean' interfaces and whose contact lines remain fixed throughout their motions. The relative importance of forcing to damping can be increased by either increasing the amplitude of rod motion A or Reynolds number Re. It is shown that as the ratio of forcing to damping rises, for drops starting from an initial rest state a sharp increase in deformation can occur when they are forced to oscillate in the vicinity of their resonance frequencies, indicating the incipience of hysteresis. However, it is also shown that the existence of a second stable limit cycle and the occurrence of hysteresis can be observed if the drop is subjected to a so-called frequency sweep, where the forcing frequency is first increased and then decreased over a suitable range. Because the change in drop deformation response is abrupt in the vicinity of the forcing frequencies where hysteresis occurs, it should be possible to exploit the phenomenon to accurately measure the viscosity and surface tension of the drop liquid.

  20. Production of ultra-small ink jet drops using drop-on-demand (DOD) drop formation

    NASA Astrophysics Data System (ADS)

    Gao, Haijing; Xu, Qi; Harris, Michael; Basaran, Osman

    2009-11-01

    The formation of drops having radii that are smaller than the radii of the nozzle from which they are ejected is an active area of research in drop-on-demand (DOD) ink jet printing. In the last decade, Chen and Basaran (Phys Fluids, 2002; US patent, 2003) showed experimentally and computationally that several fold reduction in drop radius R (an order of magnitude reduction in drop volume V) is possible by judicious use of waveform modulation in which one or more intrinsic time scales such as capillary time, time for vorticity diffusion, and time for piezo actuation are varied. In this paper, we report the results of a computational study through which we have uncovered a novel method for achieving a factor of 5-10 reduction in R (about two to three orders of magnitude reduction in V). Scaling arguments are also developed which yield a simple expression for the size of the ultra-small drops formed as a function of the governing dimensionless groups. Formation of such small drops using DOD technology may prove especially attractive in applications involving direct printing of flexible electronics and solar cells.

  1. Review on drop towers and long drop tubes

    NASA Technical Reports Server (NTRS)

    Bayuzick, R. J.; Hofmeister, W. H.; Robinson, M. B.

    1987-01-01

    A drop tube is an enclosure in which a molten sample can be solidified while falling; three such large tubes are currently in existence, all at NASA research facilities, and are engaged in combustion and fluid physics-related experiments rather than in materials research. JPL possesses smaller tubes, one of which can be cryogenically cooled to produce glass and metal microshells. A new small drop tube will soon begin operating at NASA Lewis that is equipped with four high-speed two-color pyrometers spaced equidistantly along the column.

  2. Air induced breakup of drops.

    NASA Astrophysics Data System (ADS)

    Han, Jaehoon; Tryggvason, Gretar

    1997-11-01

    The deformation and breakup of drops subject to both sudden and gradual acceleration is examined by axisymmetric inviscid and full numerical simulations. In the full simulations, the Navier Stokes equations are solved for the fluid inside and outside of the drop by a Front Tracking/Finite Difference Method. In the limit of small density stratification, inviscid simulations show the formation of a toroidal drop for small surface tension and the formation of skirts as the surface tension is increased. The viscous computations show a similar transition plus a RbagS break up for a relatively high surface tension, but not high enough so that the drop reaches a steady state deformation. The RbagS break up mode appears when the drop slows down due to viscous dissipation after most of its fluid has accumulated in the rim, forming a torous connected by a thin film. A RbagS is formed when the rim starts to fall faster than the film. The various break up modes, as a function of the Ohnesorge and Weber (or Eotvos) numbers as well as property ratios is discussed. Supported by AFOSR.

  3. Isoelectric Focusing in a Drop

    PubMed Central

    Weiss, Noah G.; Hayes, Mark A.; Garcia, Antonio A.; Ansari, Rafat R.

    2010-01-01

    A novel approach to molecular separations is investigated using a technique termed droplet-based isoelectric focusing. Drops are manipulated discretely on a superhydrophobic surface, subjected to low voltages for isoelectric focusing, and split—resulting in a preparative separation. A universal indicator dye demonstrates the generation of stable, reversible pH gradients (3–10) in ampholyte buffers and these gradients lead to protein focusing within the drop length. Focusing was visually characterized, spectroscopically verified, and assessed quantitatively by non-invasive light scattering measurements. It was found to correlate with a quantitative model based on 1D steady state theory. This work illustrates that molecular separations can be deployed within a single open drop and the differential fractions can be separated into new discrete liquid elements. PMID:21117663

  4. Drop breakup and deformation in sudden onset strong flows

    NASA Astrophysics Data System (ADS)

    Marks, Charles Raphael

    This work characterizes the deformation and breakup of a single drop subjected to a sudden onset shear flow. The drop is immersed in a second fluid (the matrix) with which it is immiscible. A cylindrical couette device is used to create a flow field which, in the absence of the drop, would constitute a close approximation of simple shear flow. The magnitude of the imposed shear rate was greater than that which would be necessary to just break the drop. The experiments conducted were limited to matrix fluid viscosities above 7Pa˙ s and shear rates below 15/s, ensuring that the flows considered were inertialess. The matrix fluid was a corn syrup solution. The drop fluids were polybutadiene, paraffin oil and silicone oil, leading to a range of interfacial tensions. At the shear rates used in these experiments the fluids used Newtonian. Viscosity ratios (drop/matrix) ranging from 0.01 to 1 were considered. Two breakup mechanisms were observed to contribute to the dispersion of the original drop. In all cases elongative end pinching, defined by this study, caused the ends of a stretching drop to break off and form daughter drops. Breakup due to elongative end pinching was always the first breakup observed. The daughter drops formed by elongative end pinching were always the largest daughter drops formed. In cases when the experimental conditions were sufficiently stronger than the critical conditions (needed to just barely break up the drop), a second type of breakup, capillary wave breakup, was also observed. Measurement of the characteristic time scales and length scales were made of each type of breakup. The lengths (a) were found to scale as capillary numbers: Ca=a mg/s. The times (t) were found to scale as strains: s=t g. A qualitative explanation for the capillary number scaling is presented and quantitatively compared to predictions based on small deformation analysis. Additionally the daughter drop size distributions resulting from drop breakup is characterized

  5. Barriers Keep Drops Of Water Out Of Infrared Gas Sensors

    NASA Technical Reports Server (NTRS)

    Murray, Sean K.

    1996-01-01

    Infrared-sensor cells used for measuring partial pressures of CO(2) and other breathable gases modified to prevent entry of liquid water into sensory optical paths of cells. Hydrophobic membrane prevents drops of water entrained in flow from entering optical path from lamp to infrared detectors.

  6. Apparent contact angle of an evaporating drop

    NASA Astrophysics Data System (ADS)

    Morris, S. J. S.

    2012-11-01

    In experiments by Poulard et al. (2005), a sessile drop of perfectly wetting liquid evaporates from a non-heated substrate into an under-saturated mixture of vapour with an inert gas; evaporation is limited by vapour diffusion. The system exhibits an apparent contact angle θ that is a flow property. Under certain conditions, the apparent contact line was stationary relative to the substrate; we predict θ for this case. Observed values of θ are small, allowing lubrication analysis of the liquid film. The liquid and vapour flows are coupled through conditions holding at the phase interface; in particular, vapour partial pressure there is related to the local value of liquid pressure through the Kelvin condition. Because the droplet is shallow, the interfacial conditions can be transferred to the solid-liquid interface at y = 0 . We show that the dimensionless partial pressure p (x , y) and the film thickness h (x) are determined by solving ∇2 p = 0 for y > 0 subject to a matching condition at infinity, and the conditions - p = L hxx +h-3 and (h3px) x + 3py = 0 at y = 0 . The parameter L controls the ratio of Laplace to disjoining pressure. We analyse this b.v.p. for the experimentally-relevant case L --> 0 .

  7. 49 CFR 178.965 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.965 Section 178.965 Transportation... Packagings § 178.965 Drop test. (a) General. The drop test must be conducted for the qualification of all...) Special preparation for the drop test. Large Packagings must be filled in accordance with § 178.960....

  8. 49 CFR 178.1045 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.1045 Section 178.1045... Containers § 178.1045 Drop test. (a) General. The drop test must be conducted for the qualification of all... subpart. (b) Special preparation for the drop test. Flexible Bulk Containers must be filled to...

  9. 49 CFR 178.810 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.810 Section 178.810 Transportation... Drop test. (a) General. The drop test must be conducted for the qualification of all IBC design types... the drop test. (1) Metal, rigid plastic, and composite IBCs intended to contain solids must be...

  10. 49 CFR 178.603 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Drop test. 178.603 Section 178.603 Transportation... Packagings and Packages § 178.603 Drop test. (a) General. The drop test must be conducted for the... than flat drops, the center of gravity of the test packaging must be vertically over the point...

  11. Ultrasonic atomization of liquids in drop-chain acoustic fountains

    PubMed Central

    Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.; Bailey, Michael R.

    2015-01-01

    When focused ultrasound waves of moderate intensity in liquid encounter an air interface, a chain of drops emerges from the liquid surface to form what is known as a drop-chain fountain. Atomization, or the emission of micro-droplets, occurs when the acoustic intensity exceeds a liquid-dependent threshold. While the cavitation-wave hypothesis, which states that atomization arises from a combination of capillary-wave instabilities and cavitation bubble oscillations, is currently the most accepted theory of atomization, more data on the roles of cavitation, capillary waves, and even heat deposition or boiling would be valuable. In this paper, we experimentally test whether bubbles are a significant mechanism of atomization in drop-chain fountains. High-speed photography was used to observe the formation and atomization of drop-chain fountains composed of water and other liquids. For a range of ultrasonic frequencies and liquid sound speeds, it was found that the drop diameters approximately equalled the ultrasonic wavelengths. When water was exchanged for other liquids, it was observed that the atomization threshold increased with shear viscosity. Upon heating water, it was found that the time to commence atomization decreased with increasing temperature. Finally, water was atomized in an overpressure chamber where it was found that atomization was significantly diminished when the static pressure was increased. These results indicate that bubbles, generated by either acoustic cavitation or boiling, contribute significantly to atomization in the drop-chain fountain. PMID:25977591

  12. Finite element analysis of axisymmetric oscillations of sessile liquid drops

    NASA Astrophysics Data System (ADS)

    Bixler, N. E.; Benner, R. E.

    Inviscid oscillations of sessile liquid drops are simulated by the Galerkin finite element method in conjunction with the time integrator proposed by Gresho, et al. Simulations are of drops in spherical containers which are subjected to imposed oscillations of specified frequency and amplitude. Five equations govern drop response: (1) Laplace's equation for velocity potential within the drop; (2) a kinematic condition at the free surface; (3) a Bernoulli equation augmented to include gravity and capillary pressure at the free surface; (4) a kinematic condition at the solid surface; and (5) either a condition for fixed contact line or fixed contact angle. Each of these equations is modified to account for an accelerating frame of reference which moves the container. Normalized drop volume, contact angle, and gravitational Bond number are dimensionless parameters which control drop response to an imposed oscillation. Given a set of fluid properties, such as those for mercury, gravitational Bond number is uniquely defined by the container radius. Resonant frequencies and mode interaction are detected by Fourier analysis of a transient signal, such as free surface position at the pole of a spherical coordinate system. Results, especially resonant frequencies, are found to depend strongly on contact line condition. Calculation of resonant frequencies by eigenanalysis with Stewart's method is also discussed.

  13. Getting the Drop on Sediment

    ERIC Educational Resources Information Center

    Galindez, Peter

    1977-01-01

    In this exercise, students examine Aristotle's weight hypothesis by testing variously shaped marble chips. These chips are weighed and dropped down a water tube. Average fall times and weights are recorded and graphed. Students are asked to apply this information to rock and soil deposition by streams. (MA)

  14. Size distribution of detached drops

    NASA Astrophysics Data System (ADS)

    Baluev, V. V.; Stepanov, V. M.

    1989-10-01

    The law governing the size distribution of detached gas-liquid streams of drops has been determined analytically, and a comparison is carried out against experimental data existing in the literature. The derived theoretical relationships offer an excellent description of existing experimental results.

  15. Viscous effects in drop impact

    NASA Astrophysics Data System (ADS)

    Zamora, Roberto; Schroll, Robert; Blanchette, Francois; Zhang, Wendy

    2006-11-01

    We investigate the onset of splash for a viscous drop impacting a solid surface. The simulation is based on the volume-of-fluid methods of Popinet and Zaleski [Int. J. Numer. Meth. Fluids 30, 775-793 (1999)] and tracks the interface evolution explicitly. The qualitative shape evolution and the quantitative spreading dynamics are examined and compared against available experimental results.

  16. Metal particle compaction during drop-substrate impact for inkjet printing and drop-casting processes

    NASA Astrophysics Data System (ADS)

    Clancy, I.; Amarandei, G.; Nash, C.; Glowacki, B. A.

    2016-02-01

    Direct coating methods using metal particles from aqueous solutions or solvent-based inks become central in the roll-to-roll fabrication processes as these methods can lead to continuous or pre-defined conductive layers on a large variety of substrates. For good electrical conductivity, the metal particles have to be brought into contact, and traditionally, additional sintering treatments are required. Such treatments can degrade the sensitive substrates as paper or polymer films. In this study, the possibility of obtaining conductive layers at room temperature is investigated for direct coating methods with an emphasis on drop-casting and inkjet printing. Thus, it is shown that electrical conductive layers can be achieved if the metal particles can compact during the drop-substrate impact interaction. It is theoretically shown that the compaction process is directly related to the particle and ink drop size, the initial fractional particle loading of the ink, solvent viscosity, and drop velocity. The theoretical predictions on compaction are experimentally validated, and the particle compaction's influence on changes in the electrical conductivity of the resulting layers is demonstrated.

  17. The Use of Ultrasonic Waves to Study and Stimulate the Coalescence of Oil Drops in Water.

    NASA Astrophysics Data System (ADS)

    Gardner, Edward Arthur

    The coalescence of oil drops in water are studied using acoustic levitation and stimulated with acoustic cavitation. The time required for two drops to coalesce, once they have been brought into proximity of one another, is one factor that affects emulsion stability. Unlike most earlier studies, which investigate the coalescence of a single drop with an initially planar interface, the use of acoustic radiation forces allows two drops to be brought into contact and allowed to coalesce. This acoustic technique has the advantage over other drop-drop coalescence systems in that the drops remain in contact until they coalesce without the use of solid supports to control them. Additionally, acoustic cavitation is observed to deposit sufficient energy in the oil-water interface to trigger the coalescence of a pair of 2 mm diameter drops. Some of the factors that affect spontaneous and stimulated coalescence are investigated.

  18. Improved Refractometer for Measuring Temperatures of Drops

    NASA Technical Reports Server (NTRS)

    Naqwi, Amir A.

    2004-01-01

    The Dual Rainbow refractometer is an enhanced version of the Rainbow refractometer, which is added to, and extends the capabilities of, a phase Doppler particle analyzer (PDPA). A PDPA utilizes pairs of laser beams to measure individual components of velocity and sizes of drops in a spray. The Rainbow-refractometer addition measures the temperatures of individual drops. The designs of prior versions of the Rainbow refractometer have required substantial modifications of PDPA transmitting optics, plus dedicated lasers as sources of illumination separate from, and in addition to, those needed for PDPA measurements. The enhancement embodied in the Dual Rainbow refractometer eliminates the need for a dedicated laser and confers other advantages as described below. A dedicated laser is no longer needed because the Dual Rainbow refractometer utilizes one of the pairs of laser beams already present in a PDPA. Hence, the design of the Dual Rainbow refractometer simplifies the task of upgrading PDPA hardware to enable measurement of temperature. Furthermore, in a PDPA/Dual Rainbow refractometer system, a single argon-ion laser with three main wavelengths can be used to measure the temperatures, sizes, and all three components of velocity (in contradistinction to only two components of velocity in a prior PDPA/Rainbow refractometer system). In order to enable the Dual Rainbow refractometer to utilize a pair of PDPA laser beams, it was necessary to (1) find a location for the refractometer receiver, such that the combined rainbow patterns of two laser beams amount to a pattern identical to that of a single beam, (2) adjust the polarization of the two beams to obtain the strongest rainbow pattern, and (3) find a location for the PDPA receiver to obtain a linear relationship between the measured phase shift and drop size.

  19. Drop dynamics in space and interference with acoustic field (M-15)

    NASA Technical Reports Server (NTRS)

    Yamanaka, Tatsuo

    1993-01-01

    The objective of the experiment is to study contactless positioning of liquid drops, excitation of capillary waves on the surface of acoustically levitated liquid drops, and deformation of liquid drops by means of acoustic radiation pressure. Contactless positioning technologies are very important in space materials processing because the melt is processed without contacting the wall of a crucible which can easily contaminate the melt specifically for high melting temperatures and chemically reactive materials. Among the contactless positioning technologies, an acoustic technology is especially important for materials unsusceptible to electromagnetic fields such as glasses and ceramics. The shape of a levitated liquid drop in the weightless condition is determined by its surface tension and the internal and external pressure distribution. If the surface temperature is constant and there exist neither internal nor external pressure perturbations, the levitated liquid drop forms a shape of perfect sphere. If temperature gradients on the surface and internal or external pressure perturbations exist, the liquid drop forms various modes of shapes with proper vibrations. A rotating liquid drop was specifically studied not only as a classical problem of theoretical mechanics to describe the shapes of the planets of the solar system, as well as their arrangement, but it is also more a contemporary problem of modern non-linear mechanics. In the experiment, we are expecting to observe various shapes of a liquid drop such as cocoon, tri-lobed, tetropod, multi-lobed, and doughnut.

  20. Self-assembly of nanoparticles in evaporating particle-laden emulsion drops

    NASA Astrophysics Data System (ADS)

    Pack, Min; Yang, Xin; Sun, Ying

    2014-11-01

    In this study, we demonstrate the scalable fabrication of nanostructures (e.g., nanomesh and nanoring arrays) via inkjet printing of oil-in-water emulsion drops containing nanoparticles in water. Nanoscale oil drops dispersed in water are used here as templates for assembly of nanoparticles on a substrate. The effect of oil vapor pressure on particle deposition morphologies is studied by using a variety of oils. For oil drops with a lower vapor pressure, non-uniform evaporation rate along the air-water interface drives dispersed oil drops to move and accumulate near the air/water/substrate contact line. These oil drops remain on the substrate while water is evaporating enabling nanoparticles to self-assemble into nanomeshes. While keeping the same oil concentration, oil drops with a higher vapor pressure completely evaporates near the contact line before water dries out, leading to nanoparticle deposition of coffee-ring structures. If nanoparticles are confined inside the dispersed oil drops, nanoring arrays are formed as the emulsion evaporates. The characteristics of the nanomeshes and nanorings are controlled by tuning the size and concentration of oil drops and nanoparticles, substrate wettability, surfactant concentration, and vapor pressure of oil.

  1. Horizontal Drop of 21- PWR Waste Package

    SciTech Connect

    A.K. Scheider

    2007-01-31

    The objective of this calculation is to determine the structural response of the waste package (WP) dropped horizontally from a specified height. The WP used for that purpose is the 21-Pressurized Water Reactor (PWR) WP. The scope of this document is limited to reporting the calculation results in-terms of stress intensities. This calculation is associated with the WP design and was performed by the Waste Package Design group in accordance with the ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 16). AP-3.12Q, ''Calculations'' (Ref. 1 1) is used to perform the calculation and develop the document. The sketches attached to this calculation provide the potential dimensions and materials for the 21-PWR WP design.

  2. Bubble and Drop Nonlinear Dynamics experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The Bubble and Drop Nonlinear Dynamics (BDND) experiment was designed to improve understanding of how the shape and behavior of bubbles respond to ultrasound pressure. By understanding this behavior, it may be possible to counteract complications bubbles cause during materials processing on the ground. This 12-second sequence came from video downlinked from STS-94, July 5 1997, MET:3/19:15 (approximate). The BDND guest investigator was Gary Leal of the University of California, Santa Barbara. The experiment was part of the space research investigations conducted during the Microgravity Science Laboratory-1R mission (STS-94, July 1-17 1997). Advanced fluid dynamics experiments will be a part of investigations plarned for the International Space Station. (189KB JPEG, 1293 x 1460 pixels; downlinked video, higher quality not available) The MPG from which this composite was made is available at http://mix.msfc.nasa.gov/ABSTRACTS/MSFC-0300163.html.

  3. Poster — Thur Eve — 49: Unexpected Output Drops: Pitted Blackholes in Tungsten

    SciTech Connect

    Hudson, A; Pierce, G

    2014-08-15

    During the daily measurement of radiation output of a 6 MV beam on a Varian Trilogy Linear Accelerator the output dropped below 2% and initiated a call to action by physics to determine the cause. Over the course of weeks the cause of the issue was diagnosed to be a defect in the target, resulting in a drop in output and an asymmetry of the beam. Steps were taken to return the machine to clinical service while parts were on order while ensuring the safety of patient treatment. The machine target was replaced and the machine continues to operate as expected. A drop in output is usually a rarity and a defect in the target is possibly more rare. This experience demonstrated the importance of routine QC measurement, recording and analyzing daily output and symmetry values. In addition, this event showcased the importance of a multi-disciplinary approach in a high-pressure situation to effectively troubleshoot unique events to ensure consistence, safety patient treatment.

  4. Pollutant particle scavenging by rain drops

    NASA Astrophysics Data System (ADS)

    Castro, J. J.; Cârsteanu, A. A.; García, C. A.

    2003-04-01

    Scavenging of air pollutants by rain drops has been studied from various angles of the phenomenon: spatial distribution of drops, size distribution of the larger drops, and scavenging properties of individual drops have been taken into account. The latter makes the object of the present work. In order to study the movement of pollutant particles in the neighborhood of a falling rain drop, a fixed drop is subjected in situ to a vertical air current containing pollutant particles of several microns in size, originating from a Diesel engine exhaust, which are essentially composed of soot. While the speed of the air current reproduces the terminal velocity of the respective rain drop, the trajectories of the particles around the drops are being followed by digital imagery, through an optical microscope. We present the adhesion statistics of boundary layer particles to the water drops, and the incorporation of these results into a multifractal rainfall field model.

  5. The Stability of Two Connected Pendant Drops

    NASA Technical Reports Server (NTRS)

    Slobozhanin, Lev A.; Alexander, J. Iwan

    2004-01-01

    The stability of an equilibrium system of two drops suspended from circular holes is examined. The drop surfaces are disconnected surfaces of a connected liquid body. For holes of equal radii and identical pendant drops axisymmetric perturbations are always the most dangerous. The stability region for two identical drops differs considerably from that for a single drop. Loss of stability leads to a transition from a critical system of identical drops to a stable system of axisymmetric non-identical. This system of non-identical drops reaches its own stability limit (to isochoric or non-isochoric paturbations). For non-identical drops, loss of stability results in dripping or streaming from the holes. Critical volumes for non-identical drops have been calculated as functions of the Bond number, B. For unequal hole radii, stability regions have been constructed for a set of hole radius, K. The dependence of critical volumes on K and B is analyzed.

  6. Drop impact on a fiber

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Gil; Kim, Wonjung

    2016-04-01

    We present the results of a combined experimental and theoretical investigation of drop impact on a thin fiber. Using high-speed videography, we analyze the dynamics of droplet collision with a fiber. Based on the systematic experiments, we identify three outcomes of collision: capturing, single drop falling, and splitting. The outcomes are presented in a regime map, where the regime boundaries are explained through a scale analysis of forces. We also measure the liquid retention on the fiber after the droplet impact. By considering a liquid film on the fiber, we develop a mechanical model that predicts the residual water mass. Our model reveals that the residual mass depends critically on the fiber thickness and less on the impact speed. Our study can be extended to predicting the remaining droplet, critical problems in air filtration, water collection, and fiber coating.

  7. Piezoelectric Water Drop Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Al Ahmad, Mahmoud

    2014-02-01

    Piezoelectric materials convert mechanical deformation directly into electrical charges, which can be harvested and used to drive micropower electronic devices. The low power consumption of such systems on the scale of microwatts leads to the possibility of using harvested vibrational energy due to its almost universal nature. Vibrational energy harvested using piezoelectric cantilevers provides sufficient output for small-scale power applications. This work reports on vibrational energy harvesting from free-falling droplets at the tip of lead zirconate titanate piezoelectric-based cantilevers. The harvester incorporates a multimorph clamped-free cantilever made of lead zirconate titanate piezoelectric thick films. During the impact, the droplet's kinetic energy is transferred to the form of mechanical stress, forcing the piezoelectric structure to vibrate and thereby producing charges. Experimental results show an instantaneous drop-power of 2.15 mW cm-3 g-1. The scenario of a medium intensity of falling water drops, i.e., 200 drops per second, yielded a power of 0.48 W cm-3 g-1 per second.

  8. Fragmentation of hot classical drops

    SciTech Connect

    Vicentini, A.; Jacucci, G.; Pandharipande, V.R.

    1985-05-01

    Time evolution of hot drops of matter containing approx.230 or approx.130 particles is studied by classical molecular dynamics. Initially, the drops have uniform density and a sharp surface. The chosen initial conditions include three values of density and a range of temperatures wide enough to study the phenomena of evaporation, fragmentation, and total vaporization in a unified fashion. The average density and temperature of central matter is measured periodically to obtain trajectories of the evolution in the rho,T plane. These trajectories indicate that the matter expands almost adiabatically until it reaches the region of adiabatic instabilities. Density inhomogeneities develop in this region, but the matter fragments only if the expansion continues to average densities of less than one-fourth the liquid density, otherwise it recondenses into a single blob. The recondensed matter and fragments have very crooked surfaces. If the temperature is high enough, the expanding matter does not enter the region of adiabatic instabilities and totally vaporizes. For initial densities of the order of equilibrium density, matter does not fragment or develop large inhomogeneities in the region enclosed by the isothermal and adiabatic spinodals. Thus it appears unlikely that fragmentation of small drops (nuclei) can be used to study the isothermal critical region of gas-liquid phase transition. A detailed tabulation of the energies and number of monomers, dimers, light, and heavy fragments emitted in each event is presented.

  9. Thermocapillary motion of deformable drops

    NASA Technical Reports Server (NTRS)

    Haj-Hariri, Hossein; Shi, Qingping; Borhan, Ali

    1994-01-01

    The thermocapillary motion of initially spherical drops/bubbles driven by a constant temperature gradient in an unbounded liquid medium is simulated numerically. Effects of convection of momentum and energy, as well as shape deformations, are addressed. The method used is based on interface tracking on a base cartesian grid, and uses a smeared color or indicator function for the determination of the surface topology. Quad-tree adaptive refinement of the cartesian grid is implemented to enhance the fidelity of the surface tracking. It is shown that convection of energy results in a slowing of the drop, as the isotherms get wrapped around the front of the drop. Shape deformation resulting from inertial effects affect the migration velocity. The physical results obtained are in agreement with the existing literature. Furthermore, remarks are made on the sensitivity of the calculated solutions to the smearing of the fluid properties. Analysis and simulations show that the migration velocity depends very strongly on the smearing of the interfacial force whereas it is rather insensitive to the smearing of other properties, hence the adaptive grid.

  10. How to freeze drop oscillations with powders

    NASA Astrophysics Data System (ADS)

    Marston, Jeremy; Zhu, Ying; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2012-11-01

    We present experiments that show when a water drop impacts onto a bed of fine, hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. For all drop impact speeds, the drop rebounds due to the hydrophobic nature of the powder. However, we observe that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a complete coverage of powder, thus creating a deformed liquid marble. This powder coating acts to freeze the drop oscillations during rebound.

  11. Universal Behavior of the Initial Stage of Drop Impact

    NASA Astrophysics Data System (ADS)

    Klaseboer, Evert; Manica, Rogerio; Chan, Derek Y. C.

    2014-11-01

    During the early stages of the impact of a drop on a solid surface, pressure builds up in the intervening thin lubricating air layer and deforms the drop. The extent of the characteristic deformation is determined by the competition between capillary, gravitational, and inertial forces that has been encapsulated in a simple analytic scaling law. For millimetric drops, variations of the observed deformation with impact velocity V exhibit a maximum defined by the Weber and Eötvös numbers: We =1 +Eo . The deformation scales as V1 /2 at the low-velocity capillary regime and as V-1 /2 at the high-velocity inertia regime, in excellent agreement with a variety of experimental systems.

  12. Dynamics of a liquid drop in porous medium saturated by another liquid under gravity

    NASA Astrophysics Data System (ADS)

    Ivantsov, A. O.; Lyubimova, T. P.

    2016-02-01

    The work deals with numerical simulations of settling or ascension process of a liquid drop in porous media saturated by another liquid. The calculations were carried out using the Darcy model by Level set method with adaptive mesh refinement algorithm that dynamically refines computational mesh near interface. It is shown that the drop is unstable and the finger instability develops at the forefront of moving drop for any ratio of the viscosities of liquids. Under modulated pressure gradient small-scale perturbations of interface are suppressed and in the case of modulation with large enough intensity drop becomes stable.

  13. Linear tension of two-dimensional drops on planar adsorbent faces

    NASA Astrophysics Data System (ADS)

    Tovbin, Yu. K.; Zaytseva, E. S.; Rabinovich, A. B.

    2016-06-01

    The size dependence of the linear tension of round two-dimensional equilibrium drops in the vapor phase on a homogeneous surface of an adsorbent is studied at the pressure of saturated two-dimensional vapor. The calculations are based on the lattice gas model in a quasi-chemical approximation with allowance for the correlation effects of the nearest interacting molecules. Methods for calculating linear tension using the equimolecular reference line are considered. Temperature dependences of the linear tension are studied for metastable and equilibrium drops. It is found that the differences between the thermodynamic properties of two types of drops are slight over a wide range of variation in drop radii.

  14. Design and implementation of an efficient acoustically levitated drop reactor for in stillo measurements.

    PubMed

    Field, Christopher R; Scheeline, Alexander

    2007-12-01

    We present the details necessary for building an efficient acoustic drop levitator with reduced electrical power consumption and greater drop stability compared to previous designs. The system is optimized so that the levitated drop may be used as a chemical reactor. By introducing a temperature, pressure, and relative humidity sensor for feedback control of a linear actuator for adjusting resonator length, we have built a completely automated system capable of continuous levitation for extended periods of time. The result is a system capable of portable operation and interfacing with a variety of detection instrumentation for in stillo (in drop) measurements. PMID:18163744

  15. Oil-Well Cement and C3S Hydration Under High Pressure as Seen by In Situ X-Ray Diffraction, Temperatures ;= 80 degrees C with No Additives

    SciTech Connect

    Jupe, Andrew C.; Wilkinson, Angus P.; Funkhouser, Garry P.

    2012-06-28

    The hydration kinetics of a white cement and batches of both Class G and H oil-well cements were examined between 0 and 60 MPa, at {le}80 C, using in situ synchrotron X-ray diffraction. This gives a continuous measure of the C{sub 3}S (Ca{sub 3}SiO{sub 5}), CH (Ca(OH){sub 2}), C{sub 4}AF (Ca{sub 2}FeAlO{sub 5}), ettringite, and other phases in the hydrating slurries. Slurries prepared from single-phase C{sub 3}S; synthetic C{sub 4}AF, and gypsum; and white cement, synthetic C{sub 4}AF and gypsum were also examined. An increasing pressure enhanced the rate of hydration for all slurries. Analysis of the data, using a kinetic model, provided rate constants that were used to obtain activation volumes for C{sub 3}S hydration. For all the cement and C{sub 3}S slurries studied, similar activation volumes were obtained (average {Delta}V{double_dagger}{sup -}-35 cm{sup 3}/mol), indicating that the presence of cement phases other than C{sub 3}S has a modest influence on the pressure dependence of C{sub 3}S hydration. An alternative analysis, using the time at which 90% of the initial C{sub 3}S remained, gave similar activation volumes. Pressure accelerated the formation of ettringite from synthetic C{sub 4}AF in the presence of gypsum. However, in slurries containing cement, the pressure dependence of C{sub 3}S hydration plays a major role in determining the pressure dependence of ettringite formation.

  16. Impact dynamics of oxidized liquid metal drops

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Brown, Eric; Jaeger, Heinrich M.

    2013-04-01

    With exposure to air, many liquid metals spontaneously generate an oxide layer on their surface. In oscillatory rheological tests, this skin is found to introduce a yield stress that typically dominates the elastic response but can be tuned by exposing the metal to hydrochloric acid solutions of different concentration. We systematically studied the normal impact of eutectic gallium-indium (eGaIn) drops under different oxidation conditions and show how this leads to two different dynamical regimes. At low impact velocity (or low Weber number), eGaIn droplets display strong recoil and rebound from the impacted surface when the oxide layer is removed. In addition, the degree of drop deformation or spreading during impact is controlled by the oxide skin. We show that the scaling law known from ordinary liquids for the maximum spreading radius as a function of impact velocity can still be applied to the case of oxidized eGaIn if an effective Weber number We is employed that uses an effective surface tension factoring in the yield stress. In contrast, no influence on spreading from different oxidations conditions is observed for high impact velocity. This suggests that the initial kinetic energy is mostly damped by bulk viscous dissipation. Results from both regimes can be collapsed in an impact phase diagram controlled by two variables, the maximum spreading factor Pm=R0/Rm, given by the ratio of initial to maximum drop radius, and the impact number K=We/Re4/5, which scales with the effective Weber number We as well as the Reynolds number Re. The data exhibit a transition from capillary to viscous behavior at a critical impact number Kc≈0.1.

  17. Trapped liquid drop in a microchannel: Multiple stable states

    NASA Astrophysics Data System (ADS)

    Wang, Zhengjia; Chang, Cheng-Chung; Hong, Siang-Jie; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2013-06-01

    A liquid drop trapped in a microchannel, in which both contact angle (wettability) and opening angle (geometry) can vary with position, is investigated based on the minimization of free energy. The calculus of variation yields the Young-Laplace equation and its further integration leads to the general force balance. The equilibrium position of the trapped drop is determined by the balance between the area-mean capillary force and the area-mean hydrostatic pressure difference. Trapped liquid drops in truncated cones and hyperboloids are studied to elucidate our theory. As the volume of the drop trapped in the hydrophilic cones is increased, four regimes separated by three critical volumes are identified. The drop is either trapped at the narrow end or away from the cone top. The solution at the cone top satisfies the force balance by adjusting the upper contact angle, which is experimentally observed and verified by Surface Evolver (SE) simulations. Multiple stable states can exist in a particular regime. The hyperboloid tube in which the opening angle varies with position is also considered. As the gravitational strength is increased in hydrophilic hyperboloid, four regimes separated by three critical gravitational strengths are identified. The drop is either trapped near the neck or below the neck. Unlike hydrophilic cones, the drop stays near the neck of the hyperboloid due to varying opening angles. Multiple stable states are also observed. For both cone and hyperboloid, hydrophobic cases are studied as well and all theoretical solutions of the force balance agree well with SE simulation outcomes.

  18. Vaporization response of evaporating drops with finite thermal conductivity

    NASA Technical Reports Server (NTRS)

    Agosta, V. D.; Hammer, S. S.

    1975-01-01

    A numerical computing procedure was developed for calculating vaporization histories of evaporating drops in a combustor in which travelling transverse oscillations occurred. The liquid drop was assumed to have a finite thermal conductivity. The system of equations was solved by using a finite difference method programmed for solution on a high speed digital computer. Oscillations in the ratio of vaporization of an array of repetitivity injected drops in the combustor were obtained from summation of individual drop histories. A nonlinear in-phase frequency response factor for the entire vaporization process to oscillations in pressure was evaluated. A nonlinear out-of-phase response factor, in-phase and out-of-phase harmonic response factors, and a Princeton type 'n' and 'tau' were determined. The resulting data was correlated and is presented in graphical format. Qualitative agreement with the open literature is obtained in the behavior of the in-phase response factor. Quantitatively the results of the present finite conductivity spray analysis do not correlate with the results of a single drop model.

  19. Flame propagation in heterogeneous mixtures of fuel drops and air

    NASA Technical Reports Server (NTRS)

    Myers, G. D.; Lefebvre, A. H.

    1984-01-01

    Photographic methods are used to measure flame speeds in flowing mixtures of fuel props and air at atmospheric pressure. The fuels employed include a conventional fuel oil plus various blends JP 7 with stocks containing single-ring and mullti-ring aromatics. The results for stoichiometric mixtures show that flame propagation cannot occur in mixtures containing mean drop sizes larger than 300 to 400 microns, depending on the fuel type. For smaller drop sizes, down to around 60 microns, flame speed is inversely proportional to drop size, indicating that evaporation rates are limiting to flame speed. Below around 60 microns, the curves of flame speed versus mean drop size flatten out, thereby demonstrating that for finely atomized sprays flame speeds are much less dependent on evaporation rates, and are governed primarily by mixing and/or chemical reaction rates. The fuels exhibiting the highest flame speeds are those containing multi-ring aromatics. This is attributed to the higher radiative heat flux emanating from their soot-bearing flames which enhances the rate of evaporation of the fuel drops approaching the flame front.

  20. Dynamics of drop formation in an electric field

    SciTech Connect

    Notz, P.K.; Basaran, O.A.

    1999-05-01

    The effect of an electric field on the formation of a drop of an inviscid, perfectly conducting liquid from a capillary which protrudes from the top plate of a parallel-plate capacitor into a surrounding dynamically inactive, insulating gas is studied computationally. This free boundary problem which is comprised of the surface Bernoulli equation for the transient drop shape and the Laplace equation for the velocity potential inside the drop and the electrostatic potential outside the drop is solved by a method of lines incorporating the finite element method for spatial discretization. The finite element algorithm employed relies on judicious use of remeshing and element addition to a two-region adaptive mesh to accommodate large domain deformations, and allows the computations to proceed until the thickness of the neck connecting an about to form drop to the rest of the liquid in the capillary is less than 0.1% of the capillary radius. The accuracy of the computations is demonstrated by showing that in the absence of an electric field predictions made with the new algorithm are in excellent agreement with boundary integral calculations and experimental measurements on water drops. Computational predictions of the primary drop volume and drop length at breakup are reported over a wide range of values of the ratios of electrical gravitational, and inertial forces to surface tension force. When the magnitude of the step change in field strength is small, the results of the new transient calculations accord well with those of an earlier stability analysis and thereby provide yet another testament to the accuracy of the new algorithm.

  1. Critical point wetting drop tower experiment

    NASA Technical Reports Server (NTRS)

    Kaukler, W. F.; Tcherneshoff, L. M.; Straits, S. R.

    1984-01-01

    Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.

  2. How to Use Eye Drops Properly

    MedlinePlus

    ... Tablets, Suppositories, and Creams How to Use Eye Drops Properly (Using a mirror or having someone else ... gently squeeze the dropper so that a single drop falls into the pocket made by the lower ...

  3. Static, Drop, and Flight Tests on Musselman Type Airwheels

    NASA Technical Reports Server (NTRS)

    Peck, William C; Beard, Albert P

    1932-01-01

    The purpose of this investigation was to obtain quantitative information on the shock-reducing and energy-dissipating qualities of a set of 30 by 13-6 Musselman type airwheels. The investigation consisted of static, drop, and flight tests. The static tests were made with inflation pressures of approximately 0, 5, 10, 15, 20, and 25 pounds per square inch and loadings up to 9,600 pounds. The drop tests were with the inflation pressures approximately 5, 10, 15, 20, and 25 pounds per square inch and loadings of 1,840, 2,440, 3,050, and 3,585 pounds. The flight tests were made with VE-7 airplane weighing 2,153 pounds, with the tires inflated to 5, 10, and 15 pounds per square inch. The landing gears used in conjunction with airwheels were practically rigid structures. The results of the tests showed that the walls of the tires carried a considerable portion of the load, each tire supporting a load of 600 pounds with a depression of approximately 6 inches. The shock-reducing qualities, under severe tests, and the energy dissipating characteristics of the tires, under all tests, were poor. The latter was evidenced by the rebound present in all landings made. In the severe drop tests, the free rebound reached as much as 60 per cent of the free drop. The results indicate that a shock-reducing and energy-dissipating mechanism should be used in conjunction with airwheels.

  4. Wettability and spontaneous penetration of a water drop into hydrophobic pores.

    PubMed

    Choi, Hyunho; Liang, Hong

    2016-09-01

    The penetration of a water drop into hydrophobic pores reflects its instability on a porous surface. To understand the mechanism of penetration and to predict the behavior of such a drop, an investigation was conducted through experimental study combined theoretical analysis. Water drops with volumes from 0.5 to 15μL were examined on Polydimethylsiloxane (PDMS) substrates containing pores of 800μm and less in diameter. Results showed a critical condition at which a drop starts to penetrate into a certain sized pore. The critical condition presents a parabolic relationship between the volume of a water drop and the size of a hydrophobic pore. This behavior was due to a net force resulting from Laplace pressure, and capillary pressure. This force was found to be affected by the porosity, wetting angle, and there after the critical condition. The finding of this research will be beneficial for future design of structured surfaces. PMID:27267040

  5. Stable Drop Formation and Deposition Control in Ink Jet Printing of Polyvinylidene Fluoride Solution

    NASA Astrophysics Data System (ADS)

    Thorne, Nathaniel; Yang, Xin; Sun, Ying; Complex Fluids and Multiphase Transport Lab-Drexel University Team

    2013-11-01

    Using inkjet printing as an additive fabrication method is an enabling technology for low-cost, high-throughput production of flexible electronics and photonics. Polymeric materials, such as Polyvinylidene fluoride (PVDF), are widely used as dielectric materials for microelectronics, batteries, among others. However, due to its large molecular weight and incompatibility with moisture in air, the stable drop formation of PVDF solution is quite challenging. In this study, we examine the effects of solute concentration, nozzle back pressure, ejection waveform, and ambient moisture on the formation of PVDF droplets. The deposition dynamics of inkjet-printed PVDF solutions are then examined as a function of the solvent concentration. Bi-solvents of different surface tensions and vapor pressures are used to induce Marangoni flows in order to suppress the coffee-ring effect. The deposition of a single droplet and the interactions between multiple drops are examined for a better control of the deposition uniformity. Printing of lines and patterns with reduced instability is also discussed.

  6. Drag and drop display & builder

    SciTech Connect

    Bolshakov, Timofei B.; Petrov, Andrey D.; /Fermilab

    2007-12-01

    The Drag and Drop (DnD) Display & Builder is a component-oriented system that allows users to create visual representations of data received from data acquisition systems. It is an upgrade of a Synoptic Display mechanism used at Fermilab since 2002. Components can be graphically arranged and logically interconnected in the web-startable Project Builder. Projects can be either lightweight AJAX- and SVG-based web pages, or they can be started as Java applications. The new version was initiated as a response to discussions between the LHC Controls Group and Fermilab.

  7. Drop Tower and Aircraft Capabilities

    NASA Technical Reports Server (NTRS)

    Urban, David L.

    2015-01-01

    This presentation is a brief introduction to existing capabilities in drop towers and low-gravity aircraft that will be presented as part of a Symposium: Microgravity Platforms Other Than the ISS, From Users to Suppliers which will be a half day program to bring together the international community of gravity-dependent scientists, program officials and technologists with the suppliers of low gravity platforms (current and future) to focus on the future requirements and use of platforms other than the International Space Station (ISS).

  8. Ab Initio Neutron Drops with Chiral Hamiltonians

    NASA Astrophysics Data System (ADS)

    Potter, Hugh; Maris, Pieter; Vary, James

    2015-04-01

    Ab initio calculations for neutron drops are of interest for insights into neutron-rich nuclei and neutron star matter, and for examining the neutron-only sector of nucleon-nucleon and 3-nucleon interactions. I present ab initio results calculated using the no-core shell model with 2- and 3-body chiral Hamiltonians for neutron drops up to 20 neutrons confined in a 10 MeV harmonic trap. I discuss ground state energies, internal energies, radii, and evidence for pairing. In addition, excitation energies can be used to investigate the spin-orbit splittings in the p-shell and sd -shell. Prior Green's Function Monte Carlo calculations using the Argonne v8' potential with added 3-nucleon forces serve as a comparison. Supported by DOE Grants DESC0008485 (SciDAC/NUCLEI), DE-FG02-87ER40371, and NSF Grant 0904782; computational resources provided by the Oak Ridge Leadership Computing Facility (DOE Office of Science Contract DE-AC05-00OR22725) under an INCITE award.

  9. 14 CFR 91.15 - Dropping objects.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Dropping objects. 91.15 Section 91.15... AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES General § 91.15 Dropping objects. No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in...

  10. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  11. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  12. 49 CFR 572.102 - Drop test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Drop test. 572.102 Section 572.102 Transportation..., DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES Free Motion Headform § 572.102 Drop test. (a) When the headform is dropped from a height of 14.8 inches in accordance with paragraph (b)...

  13. Electrohydrodynamics of a particle-covered drop

    NASA Astrophysics Data System (ADS)

    Ouriemi, Malika; Vlahovska, Petia

    2014-11-01

    We study the dynamics of a drop nearly-completely covered with a particle monolayer in a uniform DC electric field. The weakly conducting fluid system consists of a silicon oil drop suspended in castor oil. A broad range of particle sizes, conductivities, and shapes is explored. In weak electric fields, the presence of particles increases drop deformation compared to a particle-free drop and suppresses the electrohydrodynamic flow. Very good agreement is observed between the measured drop deformation and the small deformation theory derived for surfactant-laden drops (Nganguia et al., 2013). In stronger electric fields, where drops are expected to undergo Quincke rotation (Salipante and Vlahovska, 2010), the presence of the particles greatly decreases the threshold for rotation and the stationary tilted drop configuration observed for clean drop is replaced by a spinning drop with either a wobbling inclination or a very low inclination. These behaviors resemble the predicted response of rigid ellipsoids in uniform electric fields. At even stronger electric fields, the particles can form dynamic wings or the drop implodes. The similar behavior of particle-covered and surfactant-laden drops provides new insights into understanding stability of Pickering emulsions. Supported by NSF-CBET 1437545.

  14. Two touching spherical drops in a uniaxial compressional flow: The effect of interfacial slip

    NASA Astrophysics Data System (ADS)

    Goel, Sachin; Ramachandran, Arun

    2016-05-01

    This study presents a semi-analytical solution for the problem of two touching drops with slipping interfaces pushed against each other in a uniaxial compressional flow at low capillary and Reynolds numbers. The jump in the tangential velocity at the liquid-liquid interface is modeled using the Navier slip condition. Analytical solutions of the contact force, the drop-scale stresses, and the drop-scale pressure are provided as functions of the slip coefficient (" separators=" α ) , the viscosity ratio (" separators=" κ ) , and the drop size ratio (" separators=" k ) . Since unequal drop sizes are considered, two problems are solved in the tangent sphere co-ordinate system to determine the steady state position: a pair of touching drops with its contact point at the origin of an axisymmetric straining flow, and two touching drops placed in a uniform flow parallel to the axis of symmetry of the drops. A general observation is that the effect of slip is manifested most strongly for drops whose viscosity is much greater than the suspending fluid (" separators=" κ ≫ 1 ) . For highly viscous drops, the flow and stress fields transition from those corresponding to solid particles for ακ ≪ 1, to those for inviscid drops in the limit ακ ≫ 1. The analytical expressions provided here for the contact force and the stress distributions will serve to provide the restrictions that complete the definition of the lubrication flow problem in the thin film between the two colliding drops. While the contact force that drains fluid out of the thin film is relatively unaffected by slip, the tangential stress and pressure in the near-contact region are mitigated significantly for ακ ≫ 1. The latter is expected to assist coalescence at high capillary numbers.

  15. Small drops from large nozzles

    NASA Astrophysics Data System (ADS)

    Castrejon-Pita, Alfonso Arturo; Said Mohamed, Ahmed; Castrejon-Pita, Jose Rafael; Herrada, Miguel Angel

    2015-11-01

    We report experimental and numerical results of the generation of drops which are significantly smaller than the nozzle from which they are generated. The system consists of a cylindrical reservoir and two endplates. One plate is a thin metal sheet with a small orifice in its centre which acts as the nozzle. The other end consists of a piston which moves by the action of an elecromechanical actuator which in turn is driven by sine-shape pull-mode pulses. The meniscus (formed at the nozzle) is thus first overturned, forming a cavity. This cavity collapses and a thin and fast jet emerges from its centre. Under appropriate conditions the tip of this jet breaks up and produces a single diminutive drop. A good agreement between the experimental and numerical results was found. Also, a series of experiments were performed in order to study the effects that the pulse amplitude and width, together with variations in the liquid properties, have over the final size of the droplet. Based on these experiments, a predictive law for the droplet size has been derived. This work was funded by the Royal Society (University Research Fellowship and Research Grant), the John Fell Fund (Oxford University Press), the Ministry of Science and Education (DPI2013-46485 Spain), and the Junta de Andalucia (P08-TEP-31704128 Spain).

  16. The fate of electrospray drops

    NASA Astrophysics Data System (ADS)

    Basaran, Osman; Collins, Robert; Sambath, Krishnaraj; Harris, Michael

    2015-11-01

    Drops subjected to strong electric fields emit thin fluid jets from conical structures (Taylor cones) that form at their surfaces. Such behavior has practical, e.g. electrospray mass spectrometry, and fundamental, e.g. raindrops in thunderclouds, implications. Theoretical analysis of the temporal development of such EHD tip-streaming phenomena is challenging given the large disparity in length scales between the macroscopic drops and the microscopic jets. Furthermore, there exist conflicting theories and measurements on the size and charge of these small electrospray droplets. We use theory and simulation to show that conductivity can be tuned to yield three scaling regimes for droplet radius and charge, a finding missed by previous studies. The amount of charge Q that electrospray droplets carry determines whether they are coulombically stable and charged below the Rayleigh limit of stability R or are unstable and hence prone to further explosions once formed. Previous experiments reported droplet charge values ranging from 1/10th to in excess of R. Simulations unequivocally show that electrospray droplets are coulombically stable at the instant they are created and that there exists a universal scaling law for droplet charge, Q=0.44 R.

  17. Identification of main corticosteroids as illegal feed additives in milk replacers by liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry.

    PubMed

    Fiori, M; Pierdominici, E; Longo, F; Brambilla, G

    1998-05-22

    Corticosteroids were proposed as growth promoting agents to improve commercial quality of meat. We developed a liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry (LC-APCI-MS) method able to identify the presence in milk replacers, when given by mouth, of dexamethasone, betamethasone, flumethasone, triamcinolone, predinisotone, prednisolone, methylprednisolone, fludrocortisone and beclomethasone, at levels in the range of 20-100 ppb. C18 solid-phase extraction, LC-RP C8 column separation, data acquisition (positive ions) in the scan range m/z 200-550 allowed us to differentiate and identify compounds by protonated molecules, their methanolic adducts and fragmentation patterns. PMID:9646497

  18. A pneumatic power harvesting ankle-foot orthosis to prevent foot-drop

    PubMed Central

    Chin, Robin; Hsiao-Wecksler, Elizabeth T; Loth, Eric; Kogler, Géza; Manwaring, Scott D; Tyson, Serena N; Shorter, K Alex; Gilmer, Joel N

    2009-01-01

    Background A self-contained, self-controlled, pneumatic power harvesting ankle-foot orthosis (PhAFO) to manage foot-drop was developed and tested. Foot-drop is due to a disruption of the motor control pathway and may occur in numerous pathologies such as stroke, spinal cord injury, multiple sclerosis, and cerebral palsy. The objectives for the prototype PhAFO are to provide toe clearance during swing, permit free ankle motion during stance, and harvest the needed power with an underfoot bellow pump pressurized during the stance phase of walking. Methods The PhAFO was constructed from a two-part (tibia and foot) carbon composite structure with an articulating ankle joint. Ankle motion control was accomplished through a cam-follower locking mechanism actuated via a pneumatic circuit connected to the bellow pump and embedded in the foam sole. Biomechanical performance of the prototype orthosis was assessed during multiple trials of treadmill walking of an able-bodied control subject (n = 1). Motion capture and pressure measurements were used to investigate the effect of the PhAFO on lower limb joint behavior and the capacity of the bellow pump to repeatedly generate the required pneumatic pressure for toe clearance. Results Toe clearance during swing was successfully achieved during all trials; average clearance 44 ± 5 mm. Free ankle motion was observed during stance and plantarflexion was blocked during swing. In addition, the bellow component repeatedly generated an average of 169 kPa per step of pressure during ten minutes of walking. Conclusion This study demonstrated that fluid power could be harvested with a pneumatic circuit built into an AFO, and used to operate an actuated cam-lock mechanism that controls ankle-foot motion at specific periods of the gait cycle. PMID:19527526

  19. Capillary Thinning of Particle-laden Drops

    NASA Astrophysics Data System (ADS)

    Wagoner, Brayden; Thete, Sumeet; Jahns, Matt; Doshi, Pankaj; Basaran, Osman

    2015-11-01

    Drop formation is central in many applications such as ink-jet printing, microfluidic devices, and atomization. During drop formation, a thinning filament is created between the about-to-form drop and the fluid hanging from the nozzle. Therefore, the physics of capillary thinning of filaments is key to understanding drop formation and has been thoroughly studied for pure Newtonian fluids. The thinning dynamics is, however, altered completely when the fluid contains particles, the physics of which is not well understood. In this work, we explore the impact of solid particles on filament thinning and drop formation by using a combination of experiments and numerical simulations.

  20. Spatial Distribution of Large Cloud Drops

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Knyazikhin, Yuri; Larsen, Michael; Wiscombe, Warren

    2004-01-01

    The analysis of aircraft measurements of individual drop sizes in clouds suggests that for sufficiently small volumes the mean number of cloud drops with a given radius is proportional to volume powered by a drop-size dependent exponent. For abundant small drops present, the exponent is 1 as assumed in conventional approach. However, for rarer large drops, the exponents fall below unity. We show striking examples of the spatial distribution of large cloud drops using models that simulate the observed power laws. In contrast to currently used models that assume homogeneity and therefore a Poisson distribution of cloud drops, these models show strong drop clustering, the more so the larger the drops. The degree of clustering is determined by the observed exponents. The strong clustering of large drops arises naturally from the observed power-law statistics. This clustering has vital consequences for rain physics explaining how rain can form so fast and also helps explain why remotely sensed cloud drop size is generally biased.

  1. Drop short control of electrode gap

    DOEpatents

    Fisher, Robert W.; Maroone, James P.; Tipping, Donald W.; Zanner, Frank J.

    1986-01-01

    During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.

  2. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electricity is major cost for cotton gins, representing approximately 20% of the industry’s variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significant...

  3. Pneumatic Conveying of Seed Cotton: Minimum Velocity and Pressure Drop

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electricity is a major cost for cotton gins, representing approximately 20% of variable costs. Fans used for pneumatic conveying consume the majority of electricity at cotton gins. Development of control systems to reduce the air velocity used for conveying seed cotton could significantly decrease e...

  4. Modeling of Leaching Filter Pressure Drop and Fouling Behavior

    SciTech Connect

    Rector, David R.; Stewart, Mark L.

    2010-04-01

    A new simulation capability has been developed for modeling the flow and thermal performance of chemical processes that involve multiphase, chemically-complex flows. This capability is applied to the ultrafiltration process which will be used in conjunction with caustic and/or oxidative leaching to concentrate high level waste in the Waste Treatment and Immobilization Plant (WTP) at the US DOE Hanford site. The separation of supernatant from undissolved solids is an important aspect of these processes. The design and likely operational performance of the proposed ultrafiltration system for the WTP facility have been called into question by external reviewers. Lattice methods are used to model both the pore scale filtration mechanisms in the filter material and the filter device scale performance. Simulation results are compared with data from experiments.

  5. Low pressure drop, multi-slit virtual impactor

    DOEpatents

    Bergman, Werner

    2002-01-01

    Fluid flow is directed into a multiplicity of slit nozzles positioned so that the fluid flow is directed into a gap between the nozzles and (a) a number of receiving chambers and (b) a number of exhaust chambers. The nozzles and chambers are select so that the fluid flow will be separated into a first particle flow component with larger and a second particle flow component with the smaller particles.

  6. Low pressure drop wet scrubbers save energy and improve efficiency

    SciTech Connect

    Roeder, M.L.; Phillips, N.D. )

    1987-01-01

    The evolution of wet scrubber design has responded to the need for increased efficiency without the traditional penalty of increased horsepower. This is accomplished by liquid power (ejector venturi) or a combination of gas power and air power (air atomized scrubber). For existing installations, a retrofit payback of 1-1/2 years or less is achievable. For new installations requiring a wet scrubber, an immediate realization of savings is possible.

  7. Drop Impact on to Moving Liquid Pools

    NASA Astrophysics Data System (ADS)

    Muñoz-Sánchez, Beatriz Natividad; Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Hutchings, Ian M.

    2014-11-01

    The deposition of droplets on to moving liquid substrates is an omnipresent situation both in nature and industry. A diverse spectrum of phenomena emerges from this simple process. In this work we present a parametric experimental study that discerns the dynamics of the impact in terms of the physical properties of the fluid and the relative velocity between the impacting drop and the moving liquid pool. The behaviour ranges from smooth coalescence (characterized by little mixing) to violent splashing (generation of multiple satellite droplets and interfacial vorticity). In addition, transitional regimes such as bouncing and surfing are also found. We classify the system dynamics and show a parametric diagram for the conditions of each regime. This work was supported by the EPSRC (Grant EP/H018913/1), the Royal Society, Becas Santander Universidades and the International Relationships Office of the University of Extremadura.

  8. Rain drop size densities over land and over sea

    NASA Astrophysics Data System (ADS)

    Bumke, Karl

    2010-05-01

    precipitation rate in mmh-1.The precipitation rate dependent factor in the exponential is similar to that given by Marshall and Palmer (1948). The intercept parameter, in the original Marshall Palmer formulation not depending on the rain rate, is also of the same order. A number of recent publications have shown that drop size densities of convective and stratiform rain show significant differences, too. Several procedures have been developed in the past to decide, whether precipitation is of stratiform or convective character. Here two of them are used, temporal variability in rain rates and additional information by weather radar data for the South Western Baltic Sea. Main result is that differences in drop size densities depend on the integration time of measurements. For integration times of 1 minute no significant differences can be detected at an error rate of 5%, while integration times of 10 minutes yield to significant differences between drop size densities of prevailing stratiform and convective rain. References: Großklaus, M., K.Uhlig, and L.Hasse, 1998: An Optical Disdrometer for Use in High Wind Speeds, Journal of Atmospheric and Oceanic Technology Vol. 15(4). 1051-1059 Marshall, J.S. and W.M.K.Palmer, 1948: The distribution of rain drops with size, J. Meteor., 5, 165-166

  9. Free vibrations of a spherical drop constrained at an azimuth

    NASA Astrophysics Data System (ADS)

    Ramalingam, Santhosh; Ramkrishna, Doraiswami; Basaran, Osman A.

    2012-08-01

    Two droplets coupled through a liquid filled (a) hole in a plate or (b) tube is referred to as a double droplet system (DDS) or a capillary switch. Such capillary systems are gaining increasing attention due to their utility in applications. A particularly exciting application is one where a DDS is employed as a liquid lens, one flavor of which entails using a DDS as a variable focus lens by keeping it under sustained oscillations at its natural frequencies. The natural modes of oscillation of a DDS are determined analytically here in the limit in which the plate thickness (or tube length) is vanishingly small and when the effect of gravity is negligible compared to that of surface tension. In this limit, a DDS at rest reduces to two spherical caps that are pinned to and coupled along a common circular ring of contact of negligible thickness. Here, the caps are taken to be complementary pieces of a sphere so that the equilibrium state of the system is a sphere that is constrained by a ring of negligible thickness at an azimuthal angle with respect to the center of the sphere. Both the constrained drop and the fluid exterior to it are taken to be inviscid fluids undergoing irrotational flow. Similar to the linear oscillations of a free drop first studied by Rayleigh, the analytical formulation of the linear oscillations of the constrained drop results in a linear operator eigenvalue problem but with one additional boundary condition, i.e., that which accounts for zero shape perturbation along the circle of contact. Exploiting properties of linear operators, an implicit expression is obtained for the frequency of each mode of oscillation, a feat that appears not to have been accomplished to date in any problem involving oscillations of constrained drops. An extension of a method based on Green's functions that was developed to analyze the linear oscillations of a drop in contact with a spherical bowl [M. Strani and F. Sabetta, "Free-vibrations of a drop in partial

  10. Parametrically excited sectorial oscillation of liquid drops floating in ultrasound

    NASA Astrophysics Data System (ADS)

    Shen, C. L.; Xie, W. J.; Wei, B.

    2010-04-01

    We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters.

  11. Parametrically excited sectorial oscillation of liquid drops floating in ultrasound.

    PubMed

    Shen, C L; Xie, W J; Wei, B

    2010-04-01

    We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters. PMID:20481825

  12. Effective directional self-gathering of drops on spine of cactus with splayed capillary arrays.

    PubMed

    Liu, Chengcheng; Xue, Yan; Chen, Yuan; Zheng, Yongmei

    2015-01-01

    We report that the fast droplet transport without additional energy expenditure can be achieved on the spine of cactus (Gymnocalycium baldianum) with the assistance of its special surface structure: the cactus spine exhibits a cone-like structure covered with tilted scales. A single scale and the spine surface under it cooperatively construct a splayed capillary tube. The arrays of capillary tube formed by the overlapping scales build up the out layer of the spine. The serial drops would be driven by the asymmetric structure resulted from tilt-up scales-by-scales on the cone-shaped spine, and move directionally toward the bottom from top of spine, by means of the Laplace pressure in differences. In addition, after the past of the first droplet, thin liquid film of drop is trapped in the splayed capillary micro-tube on the surface of spine, which greatly reduces the friction of subsequential droplet transport in efficiency. This finding provides a new biological model which could be used to transport droplet spontaneously and directionally. Also this work offers a way to reduce the surface adhesion by constructing liquid film on the surface, which has great significance in prompting droplet transport efficiency. PMID:26639758

  13. Effective directional self-gathering of drops on spine of cactus with splayed capillary arrays

    NASA Astrophysics Data System (ADS)

    Liu, Chengcheng; Xue, Yan; Chen, Yuan; Zheng, Yongmei

    2015-12-01

    We report that the fast droplet transport without additional energy expenditure can be achieved on the spine of cactus (Gymnocalycium baldianum) with the assistance of its special surface structure: the cactus spine exhibits a cone-like structure covered with tilted scales. A single scale and the spine surface under it cooperatively construct a splayed capillary tube. The arrays of capillary tube formed by the overlapping scales build up the out layer of the spine. The serial drops would be driven by the asymmetric structure resulted from tilt-up scales-by-scales on the cone-shaped spine, and move directionally toward the bottom from top of spine, by means of the Laplace pressure in differences. In addition, after the past of the first droplet, thin liquid film of drop is trapped in the splayed capillary micro-tube on the surface of spine, which greatly reduces the friction of subsequential droplet transport in efficiency. This finding provides a new biological model which could be used to transport droplet spontaneously and directionally. Also this work offers a way to reduce the surface adhesion by constructing liquid film on the surface, which has great significance in prompting droplet transport efficiency.

  14. Effective directional self-gathering of drops on spine of cactus with splayed capillary arrays

    PubMed Central

    Liu, Chengcheng; Xue, Yan; Chen, Yuan; Zheng, Yongmei

    2015-01-01

    We report that the fast droplet transport without additional energy expenditure can be achieved on the spine of cactus (Gymnocalycium baldianum) with the assistance of its special surface structure: the cactus spine exhibits a cone-like structure covered with tilted scales. A single scale and the spine surface under it cooperatively construct a splayed capillary tube. The arrays of capillary tube formed by the overlapping scales build up the out layer of the spine. The serial drops would be driven by the asymmetric structure resulted from tilt-up scales-by-scales on the cone-shaped spine, and move directionally toward the bottom from top of spine, by means of the Laplace pressure in differences. In addition, after the past of the first droplet, thin liquid film of drop is trapped in the splayed capillary micro-tube on the surface of spine, which greatly reduces the friction of subsequential droplet transport in efficiency. This finding provides a new biological model which could be used to transport droplet spontaneously and directionally. Also this work offers a way to reduce the surface adhesion by constructing liquid film on the surface, which has great significance in prompting droplet transport efficiency. PMID:26639758

  15. Magnetically focused liquid drop radiator

    DOEpatents

    Botts, T.E.; Powell, J.R.; Lenard, R.

    1984-12-10

    A magnetically focused liquid drop radiator for application in rejecting energy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

  16. Magnetically focused liquid drop radiator

    DOEpatents

    Botts, Thomas E.; Powell, James R.; Lenard, Roger

    1986-01-01

    A magnetically focused liquid drop radiator for application in rejecting rgy from a spacecraft, characterized by a magnetizable liquid or slurry disposed in operative relationship within the liquid droplet generator and its fluid delivery system, in combination with magnetic means disposed in operative relationship around a liquid droplet collector of the LDR. The magnetic means are effective to focus streams of droplets directed from the generator toward the collector, thereby to assure that essentially all of the droplets are directed into the collector, even though some of the streams may be misdirected as they leave the generator. The magnetic focusing means is also effective to suppress splashing of liquid when the droplets impinge on the collector.

  17. Dynamics of Aqueous Foam Drops

    NASA Technical Reports Server (NTRS)

    Akhatov, Iskander; McDaniel, J. Gregory; Holt, R. Glynn

    2001-01-01

    We develop a model for the nonlinear oscillations of spherical drops composed of aqueous foam. Beginning with a simple mixture law, and utilizing a mass-conserving bubble-in-cell scheme, we obtain a Rayleigh-Plesset-like equation for the dynamics of bubbles in a foam mixture. The dispersion relation for sound waves in a bubbly liquid is then coupled with a normal modes expansion to derive expressions for the frequencies of eigenmodal oscillations. These eigenmodal (breathing plus higher-order shape modes) frequencies are elicited as a function of the void fraction of the foam. A Mathieu-like equation is obtained for the dynamics of the higher-order shape modes and their parametric coupling to the breathing mode. The proposed model is used to explain recently obtained experimental data.

  18. In situ studies of microbial inactivation during high pressure processing

    NASA Astrophysics Data System (ADS)

    Maldonado, Jose Antonio; Schaffner, Donald W.; Cuitiño, Alberto M.; Karwe, Mukund V.

    2016-01-01

    High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization.

  19. Spray impact on a smooth, unheated surface: drop impact cavity diameter vs time

    NASA Astrophysics Data System (ADS)

    Kuhlman, John; Taylor, Jonathan; Hillen, Nicholas; Sommers, Christopher; WVU Spray Cooling Laboratory Team

    2014-11-01

    A dense water spray impacting a smooth, unheated glass surface is studied. Average drop diameter is 90--60 microns; average axial velocity is 7.5--12 m/s for nozzle pressures of 1.4--4.2 bar gage, respectively, from PDPA data. Average spray Weber numbers are 70--130. Half the spray mass flux is due to larger drops with Weber numbers of 200--800, causing the splashed secondary drops and large impact cavities with longer lifetimes. Liquid film thickness is about 160 microns at all radii over the present range of nozzle pressures, with transient fluctuations of 30--40 microns. This thickness increases vs drop radial impact location, and decreases vs nozzle pressure. Drop impact cavity diameter from video images is 0.5 mm--1.5 mm, giving drop diameters of 100--300 microns, consistent with the PDPA data. Spray drop impact cavity growth vs time is fit approximately by (t) 0 . 2 as seen in the literature. These results will be used to improve correlations in an existing preliminary Monte Carlo model of the complex spray impact process. It is believed that the transient thin liquid films formed beneath the droplet impact cavities are an important source of heat transfer augmentation via transient conduction. Supported under NASA Cooperative Agreement NNX10AN0YA.

  20. Internal Flows in Free Drops (IFFD)

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Sadhal, Satwindar S.; Thomas, D. A.; Crouch, R. K.

    1998-01-01

    Within the framework of an Earth-based research task investigating the internal flows within freely levitated drops, a low-gravity technology development experiment has been designed and carried out within the NASA Glovebox facility during the STS-83 and STS-94 Shuttle flights (MSL-1 mission). The goal was narrowly defined as the assessment of the capabilities of a resonant single-axis ultrasonic levitator to stably position free drops in the Shuttle environment with a precision required for the detailed measurement of internal flows. The results of this entirely crew-operated investigation indicate that the approach is fundamentally sound, but also that the ultimate stability of the positioning is highly dependent on the residual acceleration characteristic of the Spacecraft, and to a certain extent, on the initial drop deployment of the drop. The principal results are: the measured dependence of the residual drop rotation and equilibrium drop shape on the ultrasonic power level, the experimental evaluation of the typical drop translational stability in a realistic low-gravity environment, and the semi-quantitative evaluation of background internal flows within quasi-isothermal drops. Based on these results, we conclude that the successful design of a full-scale Microgravity experiment is possible, and would allow accurate the measurement of thermocapillary flows within transparent drops. The need has been demonstrated, however, for the capability for accurately deploying the drop, for a quiescent environment, and for precise mechanical adjustments of the levitator.