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1

Numerical simulations of air entrainment in a plunging jet of liquid  

NASA Astrophysics Data System (ADS)

Air entrainment upon impact of a jet of liquid is a phenomenon present in wide variety of applications. We performed a series of two-dimensional simulations consisting in three different conditions of jet impingement and compared the results to experimental data. This study was first dedicated to the establishment of the numerical configuration and the setting of the injection parameters of the jet. We studied the dynamics of air entrainment by the jets impacting on the surface of the water in a tank, from the creation of the aerated cavities to the motion of the bubble plumes resulting from their deterioration of the cavities. The results concerned time-dependent and transient phenomena. To validate the simulations, we made several comparisons with experimental data, considering three angles of jet impact. Finally, we compared two numerical models for the free-surface description, using the most prevalent method in the literature and an original free-surface tracking method recently developed in our numerical tool. We showed that the formation of air cavities was similar for each condition and each numerical model, in agreement with the experimental results. Moreover, it was observed that the air entrainment had a different behavior depending on the conditions of jet impact.

Brouilliot, Denis; Lubin, Pierre

2013-11-01

2

On the Jet Impact in a Plunging Breaker  

NASA Astrophysics Data System (ADS)

Plunging breaking ship bow waves were simulated experimentally using a 2D+T wave maker in a tank that is 14.8 m long, 1.15 m wide and 2.1 m deep (water depth of 1.83 m). In the 2D+T simulation, the sequence of shapes of the flexible surface (wave board) of the wave maker reproduces the time varying intersection of one side of the ship hull with a vertical plane oriented normal to the ship's track as the ship moves in calm water at constant speed. For equivalent full-scale ship speeds greater than about 20 knots, a large plunging breaker is formed. An LIF system that employs a high-speed digital movie camera taking pictures at 256 frames per second was used to measure the temporal history of the profile of the plunging jet. In each image, the top surface of the jet is easily extracted as the intersection of the light sheet with the water surface. The bottom surface of the jet is also seen in the images, but since it is seen by looking through the jet, its profile must be obtained by using an inverse refraction method. The characteristics of the jet including the velocity and acceleration of the jet tip and the distribution of jet thickness are presented. It is interesting to note that the jet tip trajectory is ballistic, but that the vertical acceleration ranges from about 0.6 to 0.8 times the acceleration of gravity.

Shakeri, M.; Tavakolinejad, M.; Maxeiner, E. A.; Duncan, J. H.

2007-11-01

3

Plunging water jets for oil spill containment and recovery  

SciTech Connect

A compact coherent jet of water is directed downward into a body of water to create surface currents flowing outward from the jet that carry along floating substances, such as an oil slick. Relative horizontal movement between the jet and the body of water creates a bow wave that diverges downstream to push floating substances laterally of the jet as respects the direction of the relative movement. A line of such jets is used to divert an oil slick. Laterally-spaced jets in front of an oil skimmer are used to funnel an oil slick into the skimmer entrance.

Johnson, M.G.

1984-01-10

4

FIELD MANUAL FOR PLUNGING WATER JET USE IN OIL SPILL CLEANUP  

EPA Science Inventory

The use of plunging water jets can often make possible the control (and, as a consequence, the cleanup) of spilled oil and other floating pollutants in currents too swift for conventional equipment. This short, illustrated manual provides practical information for field and plann...

5

The Nearfield of a Shallow Angle Plunging Jet - Periodicity of Air Cavity Formation  

NASA Astrophysics Data System (ADS)

The plunging of a water jet into a quiescent water pool is investigated computationally, using the Volume-of-Fluid methodology in the framework of the open source utilities of OpenFOAM. For the shallow angle plunges (?< ˜20^o), our computations and previous experiments at Dynaflow Inc. revealed a distinct periodicity in the formation of large air cavities in the nearfield. In this work, we analyze the periodicity and present a closed form expression to describe it. Our analysis, based on potential flow treatment, regards the cavity as a Rankine body [Oguz et al., JFM 1995] and its motion as that of a standing wave. For the jets considered (Fr˜O(10), Re˜O(10^5), We˜O(10^3) and ?<˜20^o.), the frequency of cavity formation was found to be related to the jet diameter and gravity, independent of viscous and surface tension effects. Our analysis, which is valid only for shallow plunges, is in excellent agreement with this observation. For steeper jets, we demonstrate that this periodicity vanishes and small air cavities are chaotically drawn into the pool.

Deshpande, Suraj S.; Trujillo, Mario F.

2011-11-01

6

On the Geometrical Characteristics of Jets Produced in Plunging Breaking Bow Waves  

NASA Astrophysics Data System (ADS)

Simulated breaking bow waves were generated using a 2D+T wave maker in a tank that is 14.8 m long, 1.15 m wide and 2.1 m deep (water depth of 1.83 m). In the 2D+T simulation, the sequence of shapes of the flexible surface (wave board) of the wave maker reproduce the time varying intersection of one side of the ship hull with a vertical plane oriented normal to the ship’s track as the ship moves in calm water at constant speed. The profile histories of the breaking bow waves created by the wave maker were measured with an LIF system that employs a high-speed digital movie camera recording at 250 frames per second. The optics and camera are mounted on an instrument carriage that is set to move with the top portion of the wave board. For equivalent full scale ship speeds greater than about 20 knots, a large plunging breaker is formed. In this talk, measurements of the geometrical characteristics and motion of the plunging jet of the breaker are presented. The impact of the jet with the smooth surface of the forward face of the wave creates a large splash ahead of the impact point. The relationship between the jet characteristics and the geometrical characteristics of the splash zone are discussed.

Shakeri, M.; Tavakolinejad, M.; Mayer, M.; Kang, P.; Duncan, J. H.

2006-11-01

7

Jets of incipient liquids  

NASA Astrophysics Data System (ADS)

Jets of incipient water escaping into the atmosphere through a short channel are photographed. In some experiments. complete disintegration of the jet is observed. The relationship of this phenomenon with intense volume incipience is considered. The role of the Coanda effect upon complete opening of the jet is revealed. Measurement results of the recoil force R of the jets of incipient liquids are presented. Cases of negative thrust caused by the Coanda effect are noted. Generalization of experimental data is proposed.

Reshetnikov, A. V.; Mazheiko, N. A.; Skripov, V. P.

2000-05-01

8

A CFD analysis of the air entrainment rate due to a plunging steel jet combining mathematical models for dispersed and separated multiphase flows  

Microsoft Academic Search

The plunging jet in tapping of steel from converters or electric arc furnaces entrains gas into the steel bath contained in a ladle. Gas entrainment rate and the effect of the gas on the flow pattern in the ladle are studied by means of Computational Fluid Dynamics CFD. The work focuses on the mathematical modeling. Two numerical methods, one for

Harald Laux; Stein Tore Johansen

9

Acoustic resonances in the bubble plume formed by a plunging water jet  

Microsoft Academic Search

Experiments were performed to investigate the near-field sound from an axisym- metric conical bubble plume formed by a continuous vertical freshwater jet as it penetrates the surface of a pool of fresh water. The volume fluxes of the air and water entering the pool were carefully controlled and monitored during the experi- ments and a hydrophone detected the acoustic pressure

R. Hahn; J. B uckingham; M. J. Buckingham

2003-01-01

10

[Plunging ranula].  

PubMed

The plunging ranula is a relatively uncommon phenomenon which represents a mucus escape reaction occurring from disruption of the sublingual salivary gland. We present a retrospective study over a 10 years period on patients suffering of plunging ranula treated in Oral and Maxillo-Facial Clinic, resumed by a clinical example. These 7 patients with plunging ranula are related to all the patients operated for ranula in the same period of time in our clinic and were analyzed on age, sex, imaging exploration technique, treatment, and outcome. We found this kind of lesion both in children and young adults, between 10 to 40 years, more frequent on male (1.33/1). Two patients presented only the cervical form of ranula instead of the other five patients (both oral and cervical ranula). Only two of them received IRM examination. All of them received surgical treatment, the approach being cervical; it was removed both the cyst and the sublingual salivary gland. The surveying period, except the last case, was 1 year and includes no recurrences. We consider, besides esthetic loss that the cervical approach of plunging ranula seems to be the optimal access both on lesion and sublingual gland. PMID:16004240

Popescu, Eugenia; Gog?lniceanu, D; D?nil?, V; Popa, Cristina; Cârdei, Oana; Daniil, C; Lupa?cu, Otilia; Laba, Elisabeta

2004-01-01

11

Turbulent Diffusion in Liquid Jets.  

National Technical Information Service (NTIS)

The report summarizes research whose objective was to establish an effective method of tracking contaminants in a liquid jet. The ultimate objective was to determine the diffusion due to turbulence of contaminant particles of different sizes and specific ...

S. C. Chuang C. H. Tinsley V. W. Goldschmidt

1969-01-01

12

Cryopreservation of human ovarian tissue by direct plunging into liquid nitrogen: negative effect of disaccharides in vitrification solution.  

PubMed

Given that it has been possible to successfully cryopreserve human ovarian tissue by direct plunging into liquid nitrogen, this study was designed to establish the future direction to be taken in this line of research. Bovine oviductal epithelial fragments (as a tissue model) and large biopsy fragments (approximately 2.0 cubic mm) of human ovarian tissue were used for cryopreservation. Two protocols were tested: with permeable cryoprotectants (dimethyl sulphoxide, propylene glycol, glycerol) + egg yolk + sucrose or trehalose + a synthetic blocker of ice nucleation, Supercool X-1000; and using only permeable cryoprotectants (glycerol and ethylene glycol) + egg yolk + Supercool X-1000. The cryopreserved tissue specimens were subsequently thawed and the cryoprotectants removed by dilution in graded sucrose solutions. Both the dynamic growth and hormonal activity of the ovarian tissue pieces, vitrified using only permeable cryoprotectants, were greater than after vitrification in a mixture of permeable cryoprotectants and sucrose. Unlike the case for other reproductive tissue (spermatozoa, oocytes, embryos), these findings suggest that the cryopreservation of ovarian tissue by direct plunging into liquid nitrogen must be achieved by vitrification using only permeable cryoprotectants and agents that prevention ice formation. PMID:12447493

Isachenko, V; Isachenko, E; Rahimi, G; Krivokharchenko, A; Alabart, J L; Nawroth, F

2002-01-01

13

Liquid-sheet jets for terahertz spectroscopy.  

PubMed

We investigated liquid-sheet jets with controllable thickness for application to terahertz (THz) spectroscopy. Slit-type and colliding-jet nozzles were used to generate optically flat liquid jets. The thickness of the liquid sheet was determined precisely by spectral interference and THz time-domain-spectroscopy methods. By adjusting the collision angle of the colliding-jet nozzle, we could control the thickness of the liquid sheet from 50 to 120 ?m. PMID:24977512

Kondoh, Masato; Tsubouchi, Masaaki

2014-06-16

14

Atomization characteristics of impinging liquid jets  

NASA Technical Reports Server (NTRS)

A systematic study is presented of the atomization of impinging liquid jets investigating the effects of jet conditions (laminar versus turbulent), orifice diameter, impingement angle and jet velocity. Results are compared to current theories in terms of sheet breakup length, sheet shape and drop size. Experiments contrasting laminar and turbulent jet conditions clearly show that the jet conditions have a dramatic effect on the atomization process.

Ryan, H. M.; Anderson, W. E.; Pal, S.; Santoro, R. J.

1993-01-01

15

The Working Liquid of a Liquid-Jet Vacuum Pump.  

National Technical Information Service (NTIS)

The article describes the application of alloys with low elasticity of vapor, for example Wood's alloy, containing 62.5% gallium, 16% tin, and 21.5% indium as the working liquid for a liquid-jet vacuum pump.

E. N. Martinson K. N. Myznikov V. A. Romanenko

1967-01-01

16

Liquid Crystal Mapping of Jet Crossflow Interactions.  

National Technical Information Service (NTIS)

The use of liquid crystal thermography is discussed as a technique for visualizing the disturbance field created on a surface from which a jet is injected into a crossing flow. The study is part of an ongoing investigation of the performance of jet steeri...

M. D. Johnson

1981-01-01

17

Liquid crystal mapping of jet crossflow interactions  

Microsoft Academic Search

The use of liquid crystal thermography is discussed as a technique for visualizing the disturbance field created on a surface from which a jet is injected into a crossing flow. The study is part of an ongoing investigation of the performance of jet steering systems such as ship bow thrusters. An experimental apparatus was designed and built to provide a

M. D. Johnson

1981-01-01

18

Study of liquid jet impingement on screens  

NASA Technical Reports Server (NTRS)

A model is presented for an unconfined flow, such as a free jet, impinging on a screen which incorporates the influence of liquid deflection by the screen. The boundary layer blockage coefficient is introduced. This coefficient depends on the screen weave geometry and the jet impingement angle, and essentially accounts for the increase in fluid particle trajectory length through the screen resulting from the flow deflection. Comparisons were made with previous experimental studies to determine empirical values of the blockage coefficient. It is concluded that the new model reliably predicts the bulk flow and penetration characteristics of an impinging liquid jet interacting with a screen.

Dodge, F. T.; Ricker, R. E.

1976-01-01

19

Liquid jet waveguide for Raman spectroscopy  

NASA Astrophysics Data System (ADS)

An optofluidic jet waveguide for Raman spectroscopy is reported. In this device a micro-channel is used to produce a high speed liquid stream acting at the same time, as the solution to analyse and as an optical waveguide. The liquid waveguide, exploiting total internal reflection, is able to effectively collect the Raman signal produced by the chemical compound under analysis opportunely excited by means of a laser source. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the Raman signal towards the detection system. The waveguiding nature of a liquid jet enables high Raman signal collection and the device configuration allows strong reduction of the background as no confining walls are used to contain the solution to analyse. The performances of the system have been successfully tested on isopropyl alcohol in water solutions showing a detection limit for this chemical compound of 0.8+/-0.1%.

Persichetti, Gianluca; Testa, Genni; Bernini, Romeo

2014-03-01

20

Millisecond mixing of liquids using a novel jet nozzle  

Microsoft Academic Search

A millisecond mixing process for liquids was implemented using a new mixer design, i.e., a jet nozzle connected with a trumpet-shaped module. The jet nozzle can facilitate two or three liquid channels, performing an initial impingement mixing of liquid sheets in the thickness at millimeters. Then, the joint liquids sheet out of the jet nozzle was stretched thinner and thinner

Yinyu Hu; Zhe Liu; Jichu Yang; Yong Jin; Yi Cheng

2009-01-01

21

Electrospinning: Distribution of charges in liquid jets  

NASA Astrophysics Data System (ADS)

An analysis of the radial distribution of charges in liquid jets is presented. Two cases where considered: (1) when the charges are uniformly distributed through the jet cross-section but are allowed to concentrate at the jet surface with time; (2) when the charges reach a steady state where the Coulomb repulsion and Brownian mixing are counterbalanced keeping the charges inside the jet. Using the first model, we showed that the charge adsorption in nonpolar fluids occurs much faster than that in polar fluids. This provides the basis for the consideration of the second model applicable for polar liquids. We examined this case and found that a steady state does exist, but the concentration of charges is limited from above by a critical concentration inversely proportional to the square of the jet radius. It was shown that above this critical concentration, the charges should accumulate at the jet surface producing an infinitely large surface charge. Using this analysis, we suggest the classification of different regimes of electrospinning when the jets are mostly carrying the volume or surface charges.

Kornev, Konstantin G.

2011-12-01

22

Liquid crystal mapping of jet crossflow interactions  

NASA Astrophysics Data System (ADS)

The use of liquid crystal thermography is discussed as a technique for visualizing the disturbance field created on a surface from which a jet is injected into a crossing flow. The study is part of an ongoing investigation of the performance of jet steering systems such as ship bow thrusters. An experimental apparatus was designed and built to provide a heated surface coated with liquid crystals. For a range of jet-to-crossflow velocity ratios, the temperature field on the flat plate was visually represented. The technique allowed continual visual observation of the cooling effects of the jet as jet velocity increased. It also showed the cooling pattern similarities that exist at the same velocity ratios for different crossflow velocities. Strong visual similarities were shown to exist between the temperature distribution on the flat plate as depicted by the liquid crystals and the theoretical surface velocity field around a jet modelled as a symmetrical foil near the point of injection and a vortex sheet in the plumes.

Johnson, M. D.

1981-12-01

23

Plunging Ranula: A Case Report  

PubMed Central

Plunging ranulas, also known as deep, diving, cervical or deep plunging ranula, usually appear in conjunction with oral ranula. Rarely, these ranulas may arise independent of oral swelling. A rare case of plunging ranula without oral swelling is discussed along with review of literature.

Gupta, Ambika; Karjodkar, F. R.

2011-01-01

24

Liquid Ink Jet Printing with MOD Inks for Hybrid Microcircuits  

Microsoft Academic Search

Application of the computer-controlled impulse ink jet with liquid metallo-organic decomposition (MOD) inks is demonstrated to be feasible in printing hybrid microcircuits. The advantages of ink jet printing over conventional screen printing are discussed. The hardware and software of the ink jet printing system have been developed. The MOD ink system suitable for the ink jet has been studied. Printing

K. F. TENG; R. Vest

1987-01-01

25

Size limits the formation of liquid jets during bubble bursting  

Microsoft Academic Search

A bubble reaching an air–liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R?100 ?m. However, few studies have been devoted to small bubbles (R<100 ?m) despite the entrainment of a large

Ji San Lee; Su Ji Park; Kamel Fezzaa; Wah-Keat Lee; Byung Mook Weon; Jung Ho Je

2011-01-01

26

Dropsize correlation for cryogenic liquid-jet atomization  

NASA Technical Reports Server (NTRS)

Momentum transfer from high velocity nitrogen gas flow to liquid-nitrogen jets was investigated. A correlation of aerodynamic and liquid-surface forces with characteristic drop diameter was obtained for cryogenic liquid-jet breakup in Mach 1 gas flow. Nitrogen gas mass-flux was varied by using three differently sized two-fluid fuel atomizers with different nozzle diameters.

Ingebo, Robert D.

1990-01-01

27

Dropsize correlation for cryogenic liquid-jet atomization  

NASA Technical Reports Server (NTRS)

Momentum transfer from high velocity nitrogen gas flow to liquid-nitrogen jets was investigated. A correlation of aerodynamic and liquid-surface forces with characteristic drop diameter was obtained for cryogenic liquid-jet breakup in Mach 1 gas flow. Nitrogen gas mass-flux was varied by using three differently sized two-fluid fuel atomizers with different nozzle diameters.

Ingebo, Robert D.

1991-01-01

28

Linear stability of co-flowing liquid gas jets  

Microsoft Academic Search

A temporal, inviscid, linear stability analysis of a liquid jet and the co-flowing gas stream surrounding the jet has been performed. The basic liquid and gas velocity profiles have been computed self-consistently by solving numerically the appropriate set of coupled Navier Stokes equations reduced using the slenderness approximation. The analysis in the case of a uniform liquid velocity profile recovers

J. M. Gordillo; M. Pérez-Saborid; A. M. Gañán-Calvo

2001-01-01

29

Hydrodynamic Instabilities in Round Liquid Jets in Gaseous Crossflow  

NASA Astrophysics Data System (ADS)

Water jets in the presence of uniform perpendicular air crossflow were investigated theoretically and experimentally using high speed imaging for gaseous Weber numbers (We) below 30, small liquid jet Ohnesorge numbers, and large liquid and gaseous Reynolds numbers. Previously, a bag instability has been reported for We between 4 and 30. Jets first deform into curved sheets due to aerodynamic drag, followed by the formation of partial bubbles (bags) along the jet streamwise direction that expand and ultimately burst. Single bags were present at each streamwise position along the liquid jets in prior experiments featuring liquid jet nozzle diameters less than the capillary length of water. We have found that at larger nozzle diameters it is possible to observe multiple bags at the same streamwise jet position because single bags of such large sizes would be unstable. Theoretical predictions for individual bag expansion diameter over time agree with experimental measurements.

Scharfman, Barry; Techet, Alexandra; Bush, John

2011-11-01

30

Atomization of a liquid jet in a crossflow  

NASA Astrophysics Data System (ADS)

This presentation is on the recent development on the atomization process during the injection of a liquid jet into a high velocity gaseous cross flow. The results of experimental correlations on jet trajectory are reviewed. In addition, theoretical models for the simulation of the atomization process in jet in cross flow are discussed.

Ashgriz, Nasser

2012-06-01

31

Production of jet fuels from coal derived liquids  

Microsoft Academic Search

Amoco and Lummus Crest have developed seven cases for upgrading by-product liquids from the Great Plains Coal Gasification Plant to jet fuels, and in several of the cases, saleable chemicals in addition to jet fuels. The analysis shows that the various grades of jet fuel can be produced from the Great Plains tar oil, but not economically. However, the phenolic

B. A. Fleming; J. D. Fox; M. W. Furlong; J. G. Masin; L. P. Sault; D. F. Tatterson; L. L. Fornoff; M. A. Link; E. Stahlnecker; K. Torster

1988-01-01

32

Generation of hypersonic liquid fuel jets accompanying self-combustion  

Microsoft Academic Search

.   Aerodynamic behavior of pulsed hypersonic light oil jets injected at 2 km\\/s and 3 km\\/s is presented. Auto-ignition and combustion\\u000a of the fuel during the injection process were visualized. The combustion around the disintegrating jet was enhanced by liquid\\u000a atomization created by the very high injection pressure as well as the interfacial instability of the hypersonic jet. The\\u000a jets

Hong-Hui Shi; Kazuyoshi Takayama

1999-01-01

33

Size limits the formation of liquid jets during bubble bursting  

Microsoft Academic Search

A bubble reaching an air-liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R>>100mum. However, few studies have been devoted to small bubbles (R<100mum) despite the entrainment of a large number of

Ji San Lee; Byung Mook Weon; Su Ji Park; Jung Ho Je; Kamel Fezzaa; Wah-Keat Lee

2011-01-01

34

Jet interaction in liquid-liquid coaxial injectors  

SciTech Connect

Interaction between two conical sheets of liquid formed by a coaxial swirl injector has been studied using water in the annular orifice and potassium permanganate solution in the inner orifice. Experiments using photographic techniques have been conducted to study the influence of the inner jet on outer conical sheet spray characteristics such as spray cone angle and break-up length. The core spray has a strong influence on the outer sheet when the pressure drop in the latter is low. This is attributed to the pressure variations caused by ejector effects. This paper also discusses the merging and separation behavior of the liquid sheets which exhibits hysteresis effect while injector pressure drop is varied.

Sivakumar, D.; Raghunandan, B.N. [Indian Inst. of Science, Bangalore (India). Dept. of Aerospace Engineering

1996-06-01

35

Liquid jet pumps for two-phase flows  

Microsoft Academic Search

Isothermal compression of a bubbly secondary fluid in a mixing-throat and diffuser is described by a one-dimensional flow model of a liquid-jet pump. Friction-loss coefficients used in the four equations may be determined experimentally, or taken from the literature. The model reduces to the liquid-jet gas compressor case if the secondary liquid is zero. Conversely, a zero secondary-gas flow reduces

R. G. Cunningham

1995-01-01

36

Satellite formation and merging in liquid jet breakup  

Microsoft Academic Search

An experimental investigation of the breakup of a liquid jet using high-speed motion pictures has revealed many different breakup mechanims. The influence of disturbance amplitude and frequency on the breakup mechanism for a Weber number range of 25 to 160 is considered. The jet breakup is grouped into several distinct regions, depending on the disturbance wavelength (lambda), and the undisturbed

P. Vassallo; N. Ashgriz

1991-01-01

37

The instability of a liquid jet in a compressible airstream  

NASA Astrophysics Data System (ADS)

The instability of a liquid jet in a coflowing compressible airstream has been studied, motivated by the experimentally observed surface wave phenomenon and breakup of a liquid jet injected transversely into a compressible gas flow. The linear stability analysis of a two-dimensional plane liquid jet in a compressible airstream is formulated first to correlate the instability characteristics with the compressibility of the airstream. The small-amplitude disturbances superimposed on the mean flow inside and outside the jet are governed by Laplace's equation and the convective wave equation, respectively, along with suitable boundary conditions at the interfaces. The conditions for a valid linearization of the convective wave equation are obtained. It is established that the transient motion of the gas can dominate so that the nonlinear term due to accumulation of disturbances in the basic flow can be negligible even as the Mach number approaches unity. The dispersion relation has been developed and studied for both temporally and spatially growing modes. A physical understanding of how compressibility affects the growth rate has been made clear by applying a 1D compressible continuity equation at the interface region and studying the convection and accumulation of vorticity. Furthermore, the kinetic energy of the disturbed liquid jet is examined to see how surface tension and airstream pressure transfer energy between the liquid jet and the compressible airstream. A similar linear study using a circular liquid jet model is then formulated in order to further investigate the behavior of the axisymmetric and non-axisymmetric unstable modes. The empirically obtained sonic point criterion for predicting jet breakup has been partially explained by studying both the maximum growth rates and the transition from convective instability to absolute instability near M approx. 1 as obtained through these linear instability analyses. Furthermore, numerical simulations of the interfacial instability of a 2D plane liquid jet and of an axisymmetrical circular liquid jet in a compressible airstream are performed to investigate the nonlinear aspects of these problems. A high resolution scheme which has second order accuracy in space and time is coupled with a Lagrangian marker particle algorithm to visualize the large scale motion of the interfaces in compressible flow. A numerical algorithm based on an approximate equation of state of a compressible liquid is developed to allow this two-fluid system to be governed by the nonlinear Euler equations in conservative form. The initial growth of small disturbances given by the simulations agrees well with the instability characteristics of the jet flow established by the linear theory. The process of the jet disruption in compressible flow involves the formation of spikes and the stretching and detachment of the liquid main center core.

Li, Hsi-Shang

1992-09-01

38

Breakup of liquid jets from non-circular orifices  

NASA Astrophysics Data System (ADS)

The purpose of this investigation is to study the effect of the orifice geometry on liquid breakup. In order to develop a better understanding of the liquid jet breakup, investigations were carried out in two steps—study of low-pressure liquid jet breakup and high-pressure fuel atomization. This paper presents the experimental investigations conducted to study the flow behavior of low-pressure water jets emanating from orifices with non-circular geometries, including rectangular, square, and triangular shapes and draws a comparison with the flow behavior of circular jets. The orifices had approximately same cross-sectional areas and were machined by electro-discharge machining process in stainless steel discs. The liquid jets were discharged in the vertical direction in atmospheric air at room temperature and pressure conditions. The analysis was carried out for gage pressures varying from 0 to 1,000 psi (absolute pressures from 0.10 to 6.99 MPa). The flow behavior was analyzed using high-speed visualization techniques. To draw a comparison between flow behavior from circular and non-circular orifices, jet breakup length and width were measured. The flow characteristics were analyzed from different directions, including looking at the flow from the straight edges of the orifices as well as their sharp corners. The non-circular geometric jets demonstrated enhanced instability as compared to the circular jets. This has been attributed to the axis-switching phenomenon exhibited by them. As a result, the non-circular jets yielded shorter breakup lengths as compared to the circular jets. In order to demonstrate the presence of axis-switching phenomenon in square and triangular jets, the jet widths were plotted along the axial direction. This technique clearly demonstrated the axis switching occurring in square and triangular jets, which was not clearly visible unlike the case of rectangular jets. To conclude, non-circular geometry induces greater instabilities in the liquid jets, thereby leading to faster disintegration. Thus, non-circular orifice geometries can provide a cheaper solution of improving liquid breakup and thus may enhance fuel atomization as compared to the precise manufacturing techniques of drilling smaller orifices or using costly elevated fuel injection pressure systems.

Sharma, Priyesh; Fang, Tiegang

2014-02-01

39

Splattering during turbulent liquid jet impingement on solid targets  

SciTech Connect

In turbulent liquid jet impingement, a spray of droplets often breaks off of the liquid layer formed on the target. This splattering of liquid alters the efficiencies of jet impingement heat transfer processes and chemical containment safety devices, and leads to problems of aerosol formation in jet impingement cleaning processes. In this paper, the authors present a more complete study of splattering and improved correlations that extend and supersede the previous reports on this topic. The authors report experimental results on the amount of splattering for jets of water, isopropanol-water solutions, and soap-water mixtures. Jets were produced by straight tube nozzles of diameter 0.8--5.8 mm, with fully developed turbulent pipe-flow upstream of the nozzle exist. These experiments cover Weber numbers between 130--31,000, Reynolds numbers between 2,700--98,000, and nozzle-to-target separations of 0.2 [<=]l/d[<=]125. Splattering of up to 75 percent of the incoming jet liquid is observed. The results show that only the Weber number and l/d affect the fraction of jet liquid splattered. The presence of surfactants does not alter the splattering. A new correlation for the onset condition for splattering is given. In addition, the authors establish the range of applicability of the model of Lienhard et al. and the authors provide a more accurate set of coefficients for their correlation.

Bhunia, S.K.; Lienhard, J.H. V (Massachusetts Inst. of Technology, Cambridge, MA (United States). Dept. of Mechanical Engineering)

1994-06-01

40

Absolute and Convective Instability of a Liquid Jet  

NASA Technical Reports Server (NTRS)

The existence of absolute instability in a liquid jet has been predicted for some time. The disturbance grows in time and propagates both upstream and downstream in an absolutely unstable liquid jet. The image of absolute instability is captured in the NASA 2.2 sec drop tower and reported here. The transition from convective to absolute instability is observed experimentally. The experimental results are compared with the theoretical predictions on the transition Weber number as functions of the Reynolds number. The role of interfacial shear relative to all other relevant forces which cause the onset of jet breakup is explained.

Lin, S. P.; Hudman, M.; Chen, J. N.

1999-01-01

41

Cavitating Jet Method and System for Oxygenation of Liquids  

NASA Technical Reports Server (NTRS)

Reclamation and re-use of water is critical for space-based life support systems. A number of functions must be performed by any such system including removal of various contaminants and oxygenation. For long-duration space missions, this must be done with a compact, reliable system that requires little or no use of expendables and minimal power. DynaJets cavitating jets can oxidize selected organic compounds with much greater energy efficiency than ultrasonic devices typically used in sonochemistry. The focus of this work was to develop cavitating jets to simultaneously accomplish the functions of oxygenation and removal of contaminants of importance to space-structured water reclamation systems. The innovation is a method to increase the concentration of dissolved oxygen or other gasses in a liquid. It utilizes a particular form of novel cavitating jet operating at low to moderate pressures to achieve a high-efficiency means of transporting and mixing the gas into the liquid. When such a jet is utilized to simultaneously oxygenate the liquid and to oxidize organic compounds within the liquid, such as those in waste water, the rates of contaminant removal are increased. The invention is directed toward an increase in the dissolved gas content of a liquid, in general, and the dissolved oxygen content of a liquid in particular.

Chahine, Georges L.

2012-01-01

42

Spraying modes in coaxial jet electrospray with outer driving liquid  

NASA Astrophysics Data System (ADS)

Coaxial jet electrospray is a technique to generate microencapsules, which uses electric forces to create a coaxial microjet from two immiscible liquids. Compound droplets with narrow size distribution are produced after the jet breaks up. In this paper, the spraying modes are investigated experimentally with proper flow rates of the inner and outer liquids. Ethanol/glycerol/tween mixture (outer liquid) and cooking oil (inner liquid) are fed into the gap between outer and inner capillaries and the inner capillary, respectively. The spraying modes presented in our experiments are ``dripping mode,'' ``dripping mode in spindle,'' ``cone-jet mode,'' ``pulse mode in cone,'' and ``multijets mode'' sequentially, as the applied voltage increases. The region of stable cone-jet mode extends with decrease of the outer liquid flow rate and increase of the inner one. It is found that the spray phenomena are mainly determined by properties of the outer liquid, which is viscous and electric conductive enough. A rudimentary physical model is developed, in which both the viscosity and liquid interface tension are taken into account.

Chen, Xiaopeng; Jia, Laibing; Yin, Xiezhen; Cheng, Jiusheng; Lu, Jian

2005-03-01

43

Impinging jet separators for liquid metal magnetohydrodynamic power cycles  

NASA Technical Reports Server (NTRS)

In many liquid metal MHD power, cycles, it is necessary to separate the phases of a high-speed liquid-gas flow. The usual method is to impinge the jet at a glancing angle against a solid surface. These surface separators achieve good separation of the two phases at a cost of a large velocity loss due to friction at the separator surface. This report deals with attempts to greatly reduce the friction loss by impinging two jets against each other. In the crude impinging jet separators tested to date, friction losses were greatly reduced, but the separation of the two phases was found to be much poorer than that achievable with surface separators. Analyses are presented which show many lines of attack (mainly changes in separator geometry) which should yield much better separation for impinging jet separators).

Bogdanoff, D. W.

1973-01-01

44

Some Numerical Research of Supersonic Gaseous Jet Injected Into Liquid  

NASA Astrophysics Data System (ADS)

The article kept the laval nozzle outer radium (D) and nozzle expansion ratio as a constant. Three different underwater gas jets multiphase unsteady flows were simulated using the volume of fluid (VOF) method. It adopted standard ?--? turbulence mode and SIMPLE algorithm to solve the two-phase flow of supersonic gaseous jet injected into liquid. We got the flow structure and the main parameters of the flow field and compared and analyzed the key parameters of three different flow field.

Sun, L. H.; Hu, J.; Yu, Y.

2011-09-01

45

Transverse liquid fuel jet breakup, burning, and ignition  

SciTech Connect

An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Li, H.

1990-01-01

46

Transverse liquid fuel jet breakup, burning, and ignition  

SciTech Connect

An analytical/numerical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion first proposed by Schetz, et al. (1980). Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, have been used for sonic point calculations. An auxiliary criterion based on surface tension stability is used as a separate means of determining the breakup location. For the reacting liquid jet problem, a diffusion flame supported by a one-step chemical reaction within the gaseous boundary layer is solved along the ellipse surface in subsonic crossflow. Typical flame structures and concentration profiles have been calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integrated reaction rate along the jet cross-section is used to predict ignition position, which is found to be situated near the stagnation point. While a multi-step reaction is needed to represent the ignition process more accurately, the present calculation does yield reasonable predictions concerning ignition along a curved surface.

Li, H.

1990-12-31

47

Modeling of Turbulence Effect on Liquid Jet Atomization  

NASA Technical Reports Server (NTRS)

Recent studies indicate that turbulence behaviors within a liquid jet have considerable effect on the atomization process. Such turbulent flow phenomena are encountered in most practical applications of common liquid spray devices. This research aims to model the effects of turbulence occurring inside a cylindrical liquid jet to its atomization process. The two widely used atomization models Kelvin-Helmholtz (KH) instability of Reitz and the Taylor analogy breakup (TAB) of O'Rourke and Amsden portraying primary liquid jet disintegration and secondary droplet breakup, respectively, are examined. Additional terms are formulated and appropriately implemented into these two models to account for the turbulence effect. Results for the flow conditions examined in this study indicate that the turbulence terms are significant in comparison with other terms in the models. In the primary breakup regime, the turbulent liquid jet tends to break up into large drops while its intact core is slightly shorter than those without turbulence. In contrast, the secondary droplet breakup with the inside liquid turbulence consideration produces smaller drops. Computational results indicate that the proposed models provide predictions that agree reasonably well with available measured data.

Trinh, H. P.

2007-01-01

48

Numerical modeling for primary atomization of liquid jets  

NASA Technical Reports Server (NTRS)

In the proposed numerical model for primary atomization, surface-wave dispersion equations are solved in conjunction with the jet-embedding technique of solving mean flow equations of a liquid jet. Linear and approximate nonlinear models have been considered. In each case, the dispersion equation is solved over the whole wavelength spectrum to predict drop sizes, frequency, and liquid-mass breakup rates without using any empirical constants. The present model has been applied to several low-speed and high-speed jets. For the high-speed case (the LOX/H2 coaxial injector of the Space Shuttle Main Engine Preburner), predicted drop sizes and liquid breakup rates are in good agreement with the results of the CICM code, which have been calibrated against measured data.

Przekwas, A. J.; Chuech, S. G.; Singhal, A. K.

1989-01-01

49

Large bubble rupture sparks fast liquid jet.  

PubMed

This Letter presents the novel experimental observation of long and narrow jets shooting out in disconnecting large elongated bubbles. We investigate this phenomenon by carrying out experiments with various viscosities, surface tensions, densities and nozzle radii. We propose a universal scaling law for the jet velocity, which unexpectedly involves the bubble height to the power 3/2. This anomalous exponent suggests an energy focusing phenomenon. We demonstrate experimentally that this focusing is purely gravity driven and independent of the pinch-off singularity. PMID:23031107

Séon, Thomas; Antkowiak, Arnaud

2012-07-01

50

Combined aerodynamic and electrostatic atomization of dielectric liquid jets  

NASA Astrophysics Data System (ADS)

The electrical and atomization performance of a plane-plane charge injection atomizer using a dielectric liquid, and operating at pump pressures ranging from 15 to 35 bar corresponding to injection velocities of up to 50 m/s, is explored via low current electrical measurements, spray imaging and phase Doppler anemometry. The work is aimed at understanding the contribution of electrostatic charging relevant to typical higher pressure fuel injection systems such as those employed in the aeronautical, automotive and marine sectors. Results show that mean-specific charge increases with injection velocity significantly. The effect of electrostatic charge is advantageous at the 15-35 bar range, and an arithmetic mean diameter D 10 as low as 0.2 d is achievable in the spray core and lower still in the periphery where d is the orifice diameter. Using the data available from this higher pressure system and from previous high Reynolds number systems (Shrimpton and Yule Exp Fluids 26:460-469, 1999), the promotion of primary atomization has been analysed by examining the effect that charge has on liquid jet surface and liquid jet bulk instability. The results suggest that for the low charge density Q v ~ 2 C/m3 cases under consideration here, a significant increase in primary atomization is observed due to a combination of electrical and aerodynamic forces acting on the jet surface, attributed to the significantly higher jet Weber number ( We j) when compared to low injection pressure cases. Analysis of Sauter mean diameter results shows that for jets with elevated specific charge density of the order Q v ~ 6 C/m3, the jet creates droplets that a conventional turbulent jet would, but with a significantly lower power requirement. This suggests that `turbulent' primary atomization, the turbulence being induced by electrical forces, may be achieved under injection pressures that would produce laminar jets.

Kourmatzis, Agissilaos; Ergene, Egemen L.; Shrimpton, John S.; Kyritsis, Dimitrios C.; Mashayek, Farzad; Huo, Ming

2012-07-01

51

Production of jet fuels from coal-derived liquids  

Microsoft Academic Search

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were compared to similar fuel samples produced from petroleum. Large quantities of oxygen compounds were found in the coal-derived liquids and were removed

Knudson

1990-01-01

52

Flow of liquid jets through closely woven screens  

NASA Technical Reports Server (NTRS)

Previously developed analytical models relate pressure drop across a fine-mesh screen to throughflow velocity for duct systems. These models are shown to be unreliable for an unconfined flow, such as a free jet, impinging on a screen. A new model is developed for these kinds of systems, incorporating the important influence of liquid deflection by the screen. A new parameter, the boundary-layer blockage coefficient, is introduced. This coefficient, which depends on the screen weave geometry and the jet impingement angle, accounts for the increase in fluid path length through the screen resulting from the flow deflection. Comparisons are made with previous experimental studies to determine empirical values of the blockage coefficient. It is concluded that the new model reliably predicts the bulk flow and penetration characteristics of an impinging liquid jet interacting with a screen.

Dodge, F. T.; Ricker, R. E.

1978-01-01

53

Flow of liquid jets through closely woven screens  

NASA Technical Reports Server (NTRS)

Previously developed analytical models relate pressure drop across a fine-mesh screen to throughflow velocity for duct systems. These models are shown to be unreliable for an unconfined flow, such as a free jet, impinging on a screen. A new model is developed for these kinds of systems, incorporating the important influence of liquid deflection by the screen. A new parameter, the boundary layer blockage coefficient, is introduced. This coefficient, which depends on the screen weave geometry and the jet impingement angle, accounts for the increase in fluid path length through the screen resulting from the flow deflection. Comparisons are made with previous experimental studies to determine empirical values of the blockage coefficient. It is concluded that the new model reliably predicts the bulk flow and penetration characteristics of an impinging liquid jet interacting with a screen.

Dodge, F. T.; Ricker, R. E.

1978-01-01

54

On the numerical solution of liquid film and jet flows  

Microsoft Academic Search

The analysis of many fluid flows of practical interest such as liquid films and jets are complicated by the presence of free surface boundaries. Exact solutions are scare and increasingly, numerical methods are being applied to predict local flow properties and hydrodynamic structure. Like the unknown pressure and velocities, the shape and the position of the boundary must be determined

Jose Rafael Pacheco

1999-01-01

55

Observations of breakup processes of liquid jets using real-time X-ray radiography  

NASA Technical Reports Server (NTRS)

To unravel the liquid-jet breakup process in the nondilute region, a newly developed system of real-time X-ray radiography, an advanced digital image processor, and a high-speed video camera were used. Based upon recorded X-ray images, the inner structure of a liquid jet during breakup was observed. The jet divergence angle, jet breakup length, and fraction distributions along the axial and transverse directions of the liquid jets were determined in the near-injector region. Both wall- and free-jet tests were conducted to study the effect of wall friction on the jet breakup process.

Char, J. M.; Kuo, K. K.; Hsieh, K. C.

1988-01-01

56

Temporal instability of swirling gas jets injected in liquids  

NASA Astrophysics Data System (ADS)

A temporal linear stability analysis of an inviscid incompressible swirling gas jet injected into a co-flowing liquid was conducted. The ratio of the tangential velocity to the axial velocity (swirl number) played a significant role in the destabilization of the gas jet. Even at small gas Weber numbers, the presence of swirl caused the higher order azimuthal modes to become unstable; the growth rates, and the dominant and limiting wave numbers of the higher order modes were greater than those of the varicose and sinuous modes. The differences in growth rates, limiting and dominant wave numbers of the various azimuthal modes became significant at large gas Weber numbers. An increase in liquid viscosity resulted in a reduction in the growth rates and the dominant wave numbers. The liquid co-flow velocity controlled the phase velocity of the unstable modes.

Parthasarathy, R. N.; Subramaniam, K.

2001-10-01

57

METHOD OF LIQUID-LIQUID EXTRACTION OF BLOOD SURROGATES FOR ASSESSING HUMAN EXPOSURE TO JET FUEL  

EPA Science Inventory

A baseline method of liquid?liquid extraction for assessing human exposure to JP-8 jet fuel was established by extracting several representative compounds ranging from very volatile to semi-volatile organic compounds, including benzene, toluene, nonane, decane, undecane, tridec...

58

Parametric Investigation of Liquid Jets in Low Gravity  

NASA Technical Reports Server (NTRS)

An axisymmetric phase field model is developed and used to model surface tension forces on liquid jets in microgravity. The previous work in this area is reviewed and a baseline drop tower experiment selected for model comparison. This paper uses the model to parametrically investigate the influence of key parameters on the geysers formed by jets in microgravity. Investigation of the contact angle showed the expected trend of increasing contact angle increasing geyser height. Investigation of the tank radius showed some interesting effects and demonstrated the zone of free surface deformation is quite large. Variation of the surface tension with a laminar jet showed clearly the evolution of free surface shape with Weber number. It predicted a breakthrough Weber number of 1.

Chato, David J.

2005-01-01

59

Jet-noise reduction through liquid-base foam injection.  

NASA Technical Reports Server (NTRS)

An experimental investigation has been made of the sound-absorbing properties of liquid-base foams and of their ability to reduce jet noise. Protein, detergent, and polymer foaming agents were used in water solutions. A method of foam generation was developed to permit systematic variation of the foam density. The investigation included measurements of sound-absorption coefficents for both plane normal incidence waves and diffuse sound fields. The intrinsic acoustic properties of foam, e.g., the characteristic impedance and the propagation constant, were also determined. The sound emitted by a 1-in.-diam cold nitrogen jet was measured for subsonic (300 m/sec) and supersonic (422 m/sec) jets, with and without foam injection. Noise reductions up to 10 PNdB were measured.

Manson, L.; Burge, H. L.

1971-01-01

60

Liquid Engine Jet Atomization Workshop report  

NASA Technical Reports Server (NTRS)

The workshop was oriented to disclose information and unsettled problems to understand the fundamental physical mechanism of the droplet formation process. Based on presentation and discussion of results, recommendations were made which should lead to associated future activities. To accomplish this task, existing observations and experiments, contributing to the basic knowledge, providing data for analytical concept verification, and forming a basis for empirical correlations were solicited. Advanced analytical modeling methods or results from specific studies were requested as well as the experience and advice from injector designers. All effort is directed to advance current analytical techniques, simulating the flow behavior downstream of the injection elements in a liquid rocket combustion chamber. Such a tool can be used to optimize injector designs with respect to short length weight savings, wall material protection, or large heat energy transport to a regenerative cooling fluid, while simultaneously achieving the maximum specific impulse in performance. The liquid atomization process also forms a sound basis for combustion instability analysis.

Gross, Klaus W.

1987-01-01

61

The Plunge Phase of Friction Stir Welding  

NASA Technical Reports Server (NTRS)

Torque and plunge force during the initial plunge phase in Friction Stir Welding were measured for a 0.5 inch diameter pin entering a 2219 aluminum alloy plate. Weld structures were preserved for metallographic observation by making emergency stops at various plunge depths. The plunging pin tool is seen to be surrounded by a very fine grained layer of recrystallized metal extending substantially below the bottom of the pin, implying a shear interface in the metal below and not at the tool-metal interface. Torque and plunge force during the initial plunge phase in Friction Stir Welding are calculated from a straight forward model based on a concept to plastic flow in the vicinity of the plunging tool compatible with structural observations. The concept: a disk of weld metal seized to and rotating with the bottom of the pin is squeezed out laterally by the plunge force and extruded upwards in a hollow cylinder around the tool. As the shear surface separating rotating disk from stationary weld metal engulfs fresh metal, the fresh metal is subjected to severe shear deformation, which results in its recrystallization. Encouraging agreement between computations and measured torque and plunge force is obtained.

Nunes, Arthur; McClure, John; Avila, Ricardo

2005-01-01

62

Jet impingement and primary atomization of non-Newtonian liquids  

NASA Astrophysics Data System (ADS)

The effect of liquid rheology on the flowfield resulting from non-Newtonian impinging jets was investigated experimentally and analytically. Experimental data were acquired using a unique experimental apparatus developed to examine the jet impingement of non-Newtonian liquids. The analytical modeling was aimed at determining which physical mechanisms transform non-Newtonian impinging jets into a sheet with waves on its surface, how those waves influence sheet fragmentation and subsequent ligament formation, and how those ligaments break up to form drops (primary atomization). Prior to impinging jet measurements, the rheological properties of 0.5 wt.-% CMC-7HF, 1.4 wt.-% CMC-7MF, 0.8 wt.-% CMC-7MF, 0.06 wt.-% CMC-7MF 75 wt.-% glycerin, 1 wt.-% Kappa carrageenan, and 1 wt.-% Agar were determined through the use of rotational and capillary rheometers. Two approaches were used to experimentally measure solid-like gel propellant simulant static surface tension. All liquids exhibited pseudoplastic rheological behavior. At various atomizer geometric and flow parameters sheet instability wavelength, sheet breakup length, ligament diameter, and drop sizes were measured from high-speed video images. Results showed that viscosity dependence on shear rate is not the sole factor that determines atomization likelihood. Instead, a key role is played by the interaction of the gelling agent with the solvent at the molecular level. For instance, despite high jet exit velocities and varying atomizer geometric parameters HPC gel propellant simulants did not atomize. The molecular nature of HPC results in physical entanglement of polymer chains when gelled, which resists liquid breakup and subsequent spray formation. However, atomization was achieved with Agar, which absorbs the water and forms a network around it rather than bonding to it. The measured liquid sheet instability wavelength, sheet breakup length, ligament diameter, and drop sizes were compared to predictions from a linear stability theory model, which employed the Bird-Carreau pseudoplastic rheology model and semi-empirical theories of sheet breakup length taken from the literature. Analytical results accurately predicted experiment data for all investigated formulations, with the exception of 1 wt.-% Agar. This is attributed to Agar's slightly different chemical molecular structure and its effect on resultant atomization. Overall, the linear stability theory developed here shows an improvement over previous linear stability theories which consistently over-predicted results.

Mallory, Jennifer A.

63

Effect of gas mass flux on cryogenic liquid jet breakup  

NASA Technical Reports Server (NTRS)

A scattered-light scanning instrument developed at NASA Lewis Research Center was used to measure the characteristic drop size of clouds of liquid nitrogen droplets. The instrument was calibrated with suspensions of monosized polystyrene spheres. In this investigation of the mechanism of liquid nitrogen jet disintegration in a high-velocity gas flow, the Sauter mean diameter, D32, was found to vary inversely with the nitrogen gas mass flux raised to the power 1.33. Values of D32 varied from 5 to 25 microns and the mass flux exponent of 1.33 agrees well with theory for liquid jet breakup in high-velocity gas flows. The loss of very small droplets due to the high vaporization rate of liquid nitrogen was avoided by sampling the spray very close to the atomizer, i.e., 1.3 cm downstream of the nozzle orifice. The presence of high velocity and thermal gradients in the gas phase also made sampling of the particles difficult. As a result, it was necessary to correct the measurements for background noise produced by both highly turbulent gas flows and thermally induced density gradients in the gas phase.

Ingebo, R. D.

1992-01-01

64

Spray Characterization of Gas-to-Liquid Synthetic Jet Fuels  

NASA Astrophysics Data System (ADS)

In the recent years, development of alternative jet fuels is gaining importance owing to the demand for cleaner combustion. In addition to having energy density that matches those of conventional fuels, alternate jet fuels need to possess vital qualities such as rapid atomization and vaporization, quick re-ignition at high altitude, less emission, and poses ease of handling. The fuel preparatory steps (atomization and vaporization) and mixing in a combustion chamber play a crucial role on the subsequent combustion and emission characteristics. Gas-to-Liquid (GTL) synthetic jet fuel obtained from Fischer-Tropsch synthesis has grabbed the global attention due to its cleaner combustion characteristics as a result of the absence of aromatics and sulphur. As a part of an on-going joint effort between Texas A&M at Qatar (TAMUQ), Rolls-Royce (UK), and German Aerospace Laboratory (DLR), a spray characterization experimental facility is set up at TAMUQ to study the spray characteristics of GTL fuel and highlights the influence of change in fuel composition on the spray characteristics. In this work, spray characteristics such as droplet size, velocity, and distribution of different GTL fuel blends is investigated and compared with the spray characteristics of conventional JetA1 fuel.

Kannaiyan, Kumaran; Sadr, Reza

2011-11-01

65

Production of jet fuel from coal-derived liquids  

SciTech Connect

Amoco and Lummus Crest are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Analytical characterizations of these three by-products indicate the range of products that can be manufactured from each, and potential problems which could be encountered during refining. These characterizations, along with limited experimental data and Amoco's proprietary process models, were used to design conceptual processing schemes for maximizing the production of Grades JP-4, JP-8, and high density (JP-8X) jet fuels from the by-product liquids. In addition to the maximum jet fuel schemes, conceptual designs have also been formulated for maximizing profits from refining of the Great Plains by-products. Conceptual processing schemes for profitable production of JP-4, JP-8, and JP-8X have been developed, as has a maximum profit'' case. All four of these additional cases have now been transferred to Lummus for design and integration studies. Development of these schemes required the use of linear programming technology. This technology includes not only conventional refining processes which have been adapted for use with coal-derived liquids (e.g. hydrotreating, hydrocracking), but also processes which may be uniquely suited to the Great Plains by-products such as cresylic acid extraction, hydordealkylation, and needle coking. 6 figs., 3 tabs.

Furlong, M.W.; Fox, J.D.; Masin, J.G.; Soderberg, D.J.

1987-01-01

66

Cone-jet electrospray in a dielectric liquid atmosphere  

NASA Astrophysics Data System (ADS)

Dispersion of liquids in a gas atmosphere or vacuum by applying an intense electric field is a well-known phenomenon. In fact, when the electric field on a liquid surface reaches a threshold value, the surface becomes unstable and forms a conical meniscus from whose vertex charge and mass are emitted. The conical meniscus attached to the end of a capillary needle and the emitted jet are steady for an appropriate range of values of both the applied electric field and the flow rate injected through the needle. Semi-conducting liquids can also be steadily dispersed into a dielectric liquid atmosphere in the cone jet mode. In this work, we report some experimental results of the electrospraying of water, ethylene-glycol, and glycerol in both heptane and hexane. The technique may be of interest for the production of fine emulsions, coating of particles containing drugs or any other substance, etc. The experimental setup for the spraying does not differ substantially from those used in standard electrosprays in gas atmosphere or vacuum. Measurements of the current emitted from the cone and the size of the particles as well as their standard deviation in size have been obtained as a function of the injected flow rate and the applied voltage. A Sympatec system has been used for measurements of the droplet size and the dispersion of the hydrosol. The influence of the liquids properties, such as electrical conductivity, permittivity ratio, and surface tension of the couple of liquids, on the scaling laws has been also investigated. Results agree well with the scaling laws for electrosprays in air.

Barrero, Antonio; López-Herrera, José M.; Boucard, Arnaud; Loscertales, Ignacio G.; Márquez, Manuel

2002-11-01

67

Jetting dripping transition of a liquid jet in a lower viscosity co-flowing immiscible liquid: the minimum flow rate in flow focusing  

Microsoft Academic Search

We study the jetting dripping (J D) transition of a flow-focused viscous liquid jet surrounded by a co-flowing immiscible, lower viscosity liquid. A theoretical model describing wave propagation in open cylindrical flows has been adapted to our problem and further expanded to incorporate spatio-temporal stability considerations (global modes). The J D transition sets the minimum liquid flow rate issuing as

Alfonso M. Gañán-Calvo; Pascualriesco-Chueca

2006-01-01

68

Sub-picosecond ballistic imaging of a liquid jet  

NASA Astrophysics Data System (ADS)

A diesel jet visualisation based on an ultra-short light pulse and a time-resolved detection is proposed. An optical gate, consisting of a beta barium borate crystal, allows to separate ballistic, refractive and scattered light. An imaging pulse passes through the studied medium, while a gating pulse is used to open the gate. With this configuration, a spatial resolution of 10 ?m and a temporal resolution of 270 fs are obtained. The gate duration is compatible with the typical dimensions of a liquid jet generated by a commercial automotive fuel injector. Preliminary results show that spatio-temporal diagrams of transmitted light through a spray may be acquired, showing clearly the separation between ballistic, refracted and scattered light.

Idlahcen, Saïd; Rozé, Claude; Méès, Loïc; Girasole, Thierry; Blaisot, Jean-Bernard

2012-02-01

69

Nanoscale Liquid Jets Shape New Line of Business  

NASA Technical Reports Server (NTRS)

Just as a pistol shrimp stuns its prey by quickly closing its oversized claw to shoot out a shock-inducing, high-velocity jet of water, NanoMatrix, Inc., is sending shockwaves throughout the nanotechnology world with a revolutionary, small-scale fabrication process that uses powerful liquid jets to cut and shape objects. Emanuel Barros, a former project engineer at NASA s Ames Research Center, set out to form the Santa Cruz, California-based NanoMatrix firm and materialize the micro/nano cutting process partially inspired by the water-spewing crustacean. Early on in his 6-year NASA career, Barros led the development of re-flown flight hardware for an award-winning Spacelab project called NeuroLab. This project, the sixteenth and final Spacelab mission, focused on a series of experiments to determine the effects of microgravity on the development of the mammalian nervous system.

2003-01-01

70

Experiments on annular liquid jet instability and on the formation of liquid shells  

NASA Technical Reports Server (NTRS)

An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Experiments are described in which such a flow is generated by an annular nozzle operated at fairly specific conditions. It is shown that periodic, axisymmetric oscillations arise spontaneously within the cylindrical sheet emerging from the nozzle and grow with such rapidity along the axial dimension that a sealing-off and encapsulation of the core gas occurs within a few jet diameters. This is closely followed by a pinchoff of the liquid between adjacent bubbles. The liquid shells set free thereby assume spherically symmetric form under capillary forces, and each contains a precisely uniform measure of gas and of liquid on account of the extremely high frequency-stability of the process. Description is given of the fluid dynamic processes by which the shells are formed, and mention is made of exploiting the instability for the production of rigid shells for technological applications.

Kendall, J. M.

1986-01-01

71

Calculation of the hydrodynamic parameters of a low-pressure jet liquid distributor  

Microsoft Academic Search

The low-pressure jet liquid separator in packed heat-mass-exchange equipment must ensure sufficient, uniform, and maximally\\u000a stable flow of liquid through the openings in the distributor plate with the jet energy required for overcoming the forces\\u000a of the surface tension of the liquid in conversion of jet flow to film flow over the surfaces of the packing. The pressure\\u000a of the

R. A. Perlov; A. V. Sokolovskii

1999-01-01

72

Acoustic excitation of liquid fuel droplets and coaxial jets  

NASA Astrophysics Data System (ADS)

This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase of the acoustic field generated within the chamber on the dark core length and the inner jet spreading angles is presented and the stability of coaxial flows in the current flow regime is discussed with respect to evidence for convective and absolute jet instabilities under different operating conditions.

Rodriguez, Juan Ignacio

73

Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup  

NASA Technical Reports Server (NTRS)

Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. This study aims to model the turbulence effect in the atomization process of a cylindrical liquid jet. Two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O Rourke et al, are further extended to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, an additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. The drop size formed from this breakup regime is estimated based on the energy balance before and after the breakup occurrence. This paper describes theoretical development of the current models, called "T-blob" and "T-TAB", for primary and secondary breakup respectivety. Several assessment studies are also presented in this paper.

Trinh, Huu P.; Chen, C. P.

2005-01-01

74

Liquid jet generated by thermocavitation bubbles within a droplet  

NASA Astrophysics Data System (ADS)

High-speed video imaging was used to study the dynamic behavior of cavitation bubbles induced by a continuous wave (CW) laser into highly absorbing droplets water containing copper nitrate (CuNO4). The droplet lays horizontally on a glass surface and the laser beam (?=975 nm) propagates vertically from underneath, across the glass and into the droplet. This beam is focused ?=400 ?m above the glass-liquid interface in order to produce the largest bubble as possible (Rmax ~ 1mm). In our experiment the thermocavitation bubbles are always in contact with the substrate, taking a hemispherical shape, regardless of where the laser focal point is, as opposed to the other methods that involved nano and picosecond laser pulses, where bubbles may nucleate and grow within the bulk of the fluid. We focus on the liquid jet which emerges out the droplet at velocities of about 3 m/s, due to the acoustic pressure wave (APW) emitted immediately after the bubble collapse, and after it breaks up into a secondary droplet or droplets depending of the droplet's volume, showing an alternative way of droplet generator that is simplest, light and cheaper. The dynamics of cavitation bubbles in confined geometries (drops) offers a rich hydrodynamic and the liquid jet generated after the bubble collapse could be used like acoustic waveguide, as was showed by Nicolas Bertin et. al.

Padilla-Martinez, J. P.; Banks, Darren; Ramirez-San-Juan, J. C.; Aguilar, G.; Ramos-Garcia, R.

2013-03-01

75

ELECTROHYDRODYNAMICS OF ELECTRIFIED LIQUID MENISCUS AND EMITTED JETS—NONEQUILIBRIUM SURFACE PHENOMENA  

Microsoft Academic Search

The present work deals with the cone-jet mode of electrospray atomization of liquids at sufficiently low flow rates. In this case, the meniscus shape almost coincides with Taylor’s cone and the emitted jet is extremely thin. Its diameter is many orders of magnitude smaller than meniscus dimensions, while the jet length is usually comparable with them. These features of the

Leonid T. Cherney

1999-01-01

76

Boiling hysteresis of impinging circular submerged jets with highly wetting liquids  

Microsoft Academic Search

An experimental study was carried out to characterize the boiling hysteresis of impinging circular submerged jets with highly wetting liquids. The effects of noncondensable gases and surface aging on boiling curves were considered. The present study focused on the effects of jet parameters (jet exit velocity, radial distance from the stagnation point and nozzle diameter) and fluid subcooling on incipient

D. W. Zhou; C. F. Ma; J. Yu

2004-01-01

77

Numerical Simulation of Liquid Jet Atomization Including Turbulence Effects  

NASA Technical Reports Server (NTRS)

This paper describes numerical implementation of a newly developed hybrid model, T-blob/T-TAB, into an existing computational fluid dynamics (CFD) program for primary and secondary breakup simulation of liquid jet atomization. This model extend two widely used models, the Kelvin-Helmholtz (KH) instability of Reitz (blob model) and the Taylor-Analogy-Breakup (TAB) secondary droplet breakup by O'Rourke and Amsden to include turbulence effects. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic scales and the initial flow conditions. For the secondary breakup, an additional turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. Several assessment studies are presented and the results indicate that the existing KH and TAB models tend to under-predict the product drop size and spray angle, while the current model provides superior results when compared with the measured data.

Trinh, Huu P.; Chen, C. P.; Balasubramanyam, M. S.

2005-01-01

78

Production of jet fuels from coal-derived liquids  

SciTech Connect

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were compared to similar fuel samples produced from petroleum. Large quantities of oxygen compounds were found in the coal-derived liquids and were removed in the refining process. Trace quantities of organo-oxygenate compounds were suspected to be present in the refined fuels. Compounds were identified and quantified as part of an effort to determine the effect of these compounds in fuel instability. Results of the analysis showed trace levels of phenols, naphthols, benzofurans, hexanol, and hydrogenated naphthols were present in levels below 100 ppM. 9 figs., 3 tabs.

Knudson, C.L.

1990-06-01

79

Red Giant Plunging Through Space  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Poster Version

This image from NASA's Spitzer Space Telescope (left panel) shows the 'bow shock' of a dying star named R Hydrae, or R Hya, in the constellation Hydra.

Bow shocks are formed where the stellar wind from a star are pushed into a bow shape (illustration, right panel) as the star plunges through the gas and dust between stars. Our own Sun has a bow shock, but prior to this image one had never been observed around this particular class of red giant star.

R Hya moves through space at approximately 50 kilometers per second. As it does so, it discharges dust and gas into space. Because the star is relatively cool, that ejecta quickly assumes a solid state and collides with the interstellar medium. The resulting dusty nebula is invisible to the naked eye but can be detected using an infrared telescope. This bow shock is 16,295 astronomical units from the star to the apex and 6,188 astronomical units thick (an astronomical unit is the distance between the sun and Earth). The mass of the bow shock is about 400 times the mass of the Earth.

The false-color Spitzer image shows infrared emissions at 70 microns. Brighter colors represent greater intensities of infrared light at that wavelength. The location of the star itself is drawn onto the picture in the black 'unobserved' region in the center.

2006-01-01

80

Effect of nozzle length-to-diameter ratio on atomization of turbulent liquid jets  

NASA Astrophysics Data System (ADS)

Breakup of liquid jets is of considerable interest motivated by its applicability in combustion and propulsion systems (CI and SI engines), and agricultural fertilizer/pesticide sprays, among others. Almost all of the practical liquid injectors introduce some degree of turbulence in the liquid jet leaving the injector passage and an intriguing question is the relative importance of the liquid turbulence, cavitation, and the aerodynamic forces in the breakup processes of fuel injectors. A better design of liquid fuel injector would reduce pollutants and increase the efficiency of liquid fuel combustion processes. An experimental study to investigate the effect of nozzle length to diameter ratio on the surface properties of turbulent liquid jets in gaseous crossflow and still air was carried out. Straight cavitation-free nozzles with length/diameter ratios of 10, 20 and 40 were used to generate turbulent liquid jets in gaseous crossflow. The present study was limited to small Ohnesorge number liquid jets (Oh < 0.01) injected in crossflow within the shear breakup regime (WeG > 110). The diagnostics consisted of pulsed shadowgraphy, pulsed digital holographic microscopy and x-ray diagnostics. The x-ray tests were conducted at the Advanced Photon Source (APS) facility of Argonne National Laboratory. The test matrix was designed to maintain the same aerodynamic forces in order to isolate the effects of jet turbulence on the breakup process. The measurements included liquid jet surface properties, breakup location of the liquid column as a whole, the breakup regime transitions, bubble size inside the jet and seeding particle displacement inside the jet structures. The results include the jet surface characteristics, the liquid column breakup lengths, bubble growth, and phenomenological analysis to explain the observed results. It is observed that for a jet breakup in crossflow the injector passage length does play a role in determining the breakup length as well as influence the characteristics of the jet upwind surface. The present results for jet breakup in still air also show that the ligament distribution follows an arrangement along the jet surface and bubble formation associated with the jet breakup as well. The x-ray diagnostic allowed the surface and internal topography of fuel jets to be visualized and the breakup mechanism in the dense-spray near-injector region to be revealed.

Osta, Anu Ranjan

81

Photoionization of Sodium Salt Solutions in a Liquid Jet  

SciTech Connect

A liquid microjet was employed to examine the gas/liquid interface of aqueous sodium halide (Na+X-, X=Cl, Br, I) salt solutions. Laser excitation at 193 nm produced and removed cations of the form H+(H2O)n and Na+(H2O)m from liquid jet surfaces containing either NaCl, NaBr or NaI. The protonated water cluster yield varied inversely with increasing salt concentration, while the solvated sodium ion cluster yield varied by anion type. The distribution of H+(H2O)n at low salt concentration is identical to that observed from low-energy electron irradiated amorphous ice and the production of these clusters can be accounted for using a localized ionization/Coulomb expulsion model. Production of Na+(H2O)m is not accounted for by this model but requires ionization of solvation shell waters and a contact ion/Coulomb expulsion mechanism. The reduced yields of Na+(H2O)m from high concentration (10-2 and 10-1 M) NaBr and NaI solutions indicate a propensity for Br- and I- at the solution surfaces and interfaces. This is supported by the observation of multiphoton induced production and desorption of Br+ and I+ from the 10-2 and 10-1 M solution surfaces.

Grieves, G. A.; Petrik, Nikolay G.; Herring-Captain, J.; Olanrewaju, B.; Aleksandrov, A.; Tonkyn, Russell G.; Barlow, Stephan E.; Kimmel, Gregory A.; Orlando, Thomas M.

2008-06-05

82

Effect of gravity on capillary instability of liquid jets.  

PubMed

The effect of gravity on the onset and growth rate of capillary instabilities in viscous liquid jets is studied. To this end, a spatial linear stability analysis of Cosserat's equations is performed using a multiscale expansion technique. A dispersion relation and expressions for the perturbation amplitude are derived to evaluate the growth rate of the most unstable axisymmetric disturbance mode. Modeling results are compared with classical results in the limit of zero Bond number, confirming the validity of this approach. Expressions for the critical Weber number, demarcating the transition between convective and absolute instability are derived as functions of capillary and Bond numbers. Parametric investigations for a range of relevant operating conditions (characterized by capillary, Weber, and Bond numbers) are performed to examine the jet breakup and the perturbation growth rate. In addition to the physical insight that is obtained from this investigation, the results that are presented in this work could also be of relevance as test cases for the algorithmic development and the verification of high-fidelity multiphase simulation codes. PMID:23767630

Amini, Ghobad; Ihme, Matthias; Dolatabadi, Ali

2013-05-01

83

Detailed Numerical Simulation of Liquid Jet In Crossflow Atomization with High Density Ratios  

NASA Astrophysics Data System (ADS)

The atomization of a liquid jet by a high speed cross-flowing gas has many applications such as gas turbines and augmentors. The mechanisms by which the liquid jet initially breaks up, however, are not well understood. Experimental studies suggest the dependence of spray properties on operating conditions and nozzle geom- etry. Detailed numerical simulations can offer better understanding of the underlying physical mechanisms that lead to the breakup of the injected liquid jet. In this work, detailed numerical simulation results of turbulent liquid jets injected into turbulent gaseous cross flows for different density ratios is presented. A finite volume, balanced force fractional step flow solver to solve the Navier-Stokes equations is employed and coupled to a Refined Level Set Grid method to follow the phase interface. To enable the simulation of atomization of high density ratio fluids, we ensure discrete consistency between the solution of the conservative momentum equation and the level set based continuity equation by employing the Consistent Rescaled Momentum Transport (CRMT) method. The impact of different inflow jet boundary conditions on different jet properties including jet penetration is analyzed and results are compared to those obtained experimentally by Brown & McDonell(2006). In addition, instability analysis is performed to find the most dominant insta- bility mechanism that causes the liquid jet to breakup. Linear instability analysis is achieved using linear theories for Rayleigh-Taylor and Kelvin- Helmholtz instabilities and non-linear analysis is performed using our flow solver with different inflow jet boundary conditions.

Ghods, Sina

84

Normal Impingement of a Circular Liquid Jet onto a Screen in a Weightless Environment  

NASA Technical Reports Server (NTRS)

The normal impingement of a circular liquid jet onto a fine-mesh screen in a weightless environment was investigated. Equations were developed to predict the velocity of the emerging jet on the downstream side of the screen as a function of screen and liquid parameters and of the velocity of the impinging jet. Additionally, the stability of the emerging jet was found to be Weber number dependent. In general, excepting at high velocities, the screen behaved much as a baffle, deflecting the major portion of the impinging flow.

Symons, E. P.

1976-01-01

85

Measurement of intact-core length of atomizing liquid jets by image deconvolution  

NASA Astrophysics Data System (ADS)

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their high liquid load fractions and hence their optical opacity. Focus was on a characteristic of the primary breakup process of round liquid jets, namely the length of the intact-liquid core. The specific application considered is that of shear-coaxial-type rocket engine injectors in which liquid oxygen is injected through the center post while high velocity gaseous hydrogen is injected through a concentric annulus, providing a shear force to the liquid jet surface. Real-time x ray radiography, capable of imaging through the dense two-phase region surrounding the liquid core, is used to make the measurements. The intact-liquid-core length data were obtained and interpreted using two conceptually different methods to illustrate the effects of chamber pressure, gas-to-liquid momentum ratio, and cavitation.

Woodward, Roger; Burch, Robert; Kuo, Kenneth; Cheung, Fan-Bill

1993-11-01

86

Microfluidic liquid jet system with compatibility for atmospheric and high-vacuum conditions.  

PubMed

We present microfluidic chip based devices that produce liquid jets with micrometer diameters while operating at very low flow rates. The chip production is based on established soft-lithographical techniques employing a three-layer design protocol. This allows the exact, controlled and reproducible design of critical parts such as nozzles and the production of nozzle arrays. The microfluidic chips reproducibly generate liquid jets exiting at perfect right angles with diameters between 20 ?m and 2 ?m, and under special circumstances, even down to 0.9 ?m. Jet diameter, jet length, and the domain of the jetting/dripping instability can be predicted and controlled based on the theory for liquid jets in the plate-orifice configuration described by Gañán-Calvo et al. Additionally, conditions under which the device produces highly reproducible monodisperse droplets at exact and predictable rates can be achieved. The devices operate under atmospheric and under vacuum conditions making them highly relevant for a wide range of applications, for example, for free-electron lasers. Further, the straightforward integration of additional features such as a jet-in-jet is demonstrated. This device design has the potential to integrate more features based on established microfluidic components and may become a standard device for small liquid jet production. PMID:24671443

Trebbin, Martin; Krüger, Kilian; DePonte, Daniel; Roth, Stephan V; Chapman, Henry N; Förster, Stephan

2014-05-21

87

Production of jet fuels from coal derived liquids  

Microsoft Academic Search

Amoco Oil Company has conducted bench- and pilot plant-scale experiments to produce jet fuels from the tar oil from the Great Plains Coal Gasification Plant in Beulah, North Dakota. Experiments show that the hydroprocessing conditions recommended in Task 1 are not severe enough to saturate the aromatics in the tar oil to meet jet fuel specifications. Alternatives were investigated. Jet

M. Furlong; J. Fox; J. Masin

1989-01-01

88

Production of Jet Fuels from Coal-Derived Liquids. Volume 15. Thermal Stability of Coal-Derived Jet Fuels.  

National Technical Information Service (NTIS)

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were com...

C. Song H. H. Schobert J. Perison R. M. Copenhaver S. Eser

1990-01-01

89

Production of Jet Fuels from Coal-Derived Liquids. Volume 14. Oxygenates Content of Coal-Derived Jet Fuels.  

National Technical Information Service (NTIS)

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were com...

C. L. Knudson

1990-01-01

90

Convective Heat Transfer from a Thick Hemispherical Plate during Free Liquid Jet Impingement  

Microsoft Academic Search

Convective heat transfer during free liquid jet impingement on a hemispherical solid plate of finite thickness has been examined. The model included the entire fluid region (impinging jet and flow spreading out over the hemispherical surface) and solid plate as a conjugate problem. Solution was done for both isothermal and constant heat flux boundary conditions at the inner surface of

Muhammad M. Rahman; Jorge C. Lallave; Cesar F. Hernandez

2008-01-01

91

Gravitational radiation from plunging orbits: Perturbative study  

NASA Astrophysics Data System (ADS)

Numerical relativity has recently yielded a plethora of results about kicks from spinning mergers which has, in turn, vastly increased our knowledge about the spin interactions of black hole systems. In this work we use black hole perturbation theory to calculate accurately the gravitational waves emanating from the end of the plunging stage of an extreme mass ratio merger in order to further understand this phenomenon. This study focuses primarily on spin induced effects with emphasis on the maximally spinning limit and the identification of possible causes of generic behavior. We find that gravitational waves emitted during the plunging phase exhibit damped oscillatory behavior, corresponding to a coherent excitation of quasinormal modes by the test particle. This feature is universal in the sense that the frequencies and damping time do not depend on the orbital parameters of the plunging particle. Furthermore, the observed frequencies are distinct from those associated with the usual free quasinormal ringing. Our calculation suggests that a maximum in radiated energy and momentum occurs at spin parameters equal to a/M=0.86 and a/M=0.81, respectively, for the plunge stage of a polar orbit. The dependence of linear momentum emission on the angle at which a polar orbit impacts the horizon is quantified. One of the advantages of the perturbation approach adopted here is that insight into the actual mechanism of radiation emission and its relationship to black hole ringing is obtained by carefully identifying the dominant terms in the expansions used.

Mino, Yasushi; Brink, Jeandrew

2008-12-01

92

On the numerical solution of liquid film and jet flows  

NASA Astrophysics Data System (ADS)

The analysis of many fluid flows of practical interest such as liquid films and jets are complicated by the presence of free surface boundaries. Exact solutions are scare and increasingly, numerical methods are being applied to predict local flow properties and hydrodynamic structure. Like the unknown pressure and velocities, the shape and the position of the boundary must be determined as part of the solution. This information is needed for the design of cooling schemes in high-temperature applications, to optimize heat treatment of metals, and to improve material production processes. The objective of this research is to develop an accurate and efficient numerical method that can be applied to the simulation of free surface flow problems, i.e. horizontal jets, impinging jets and films with and without rotation. The governing equations are written in terms of primitive variables and solved by the non-staggered grid fractional step method when hydraulic jumps are absent in the flow. The physical domain is transformed to a rectangle for two-dimensional problems or a parallelepiped for three- dimensional problems by means of a numerical mapping technique. The pressure Poisson equation is formulated in the same manner as on a staggered grid and solved with a SOR method. The location of the phase boundary is accomplished by applying both, the normal-stress condition or the kinematic boundary condition depending on the physical force that regulates the behavior of the flow. The method was applied to solve plane Newtonian jet flows. The numerical predictions are in good agreement with the results based on the finite and spectral element methods as well as the finite difference streamfunction vorticity formulation. The boundary conditions at the free surface are more accurately satisfied when compared with available data. In the presence of hydraulic jumps, the problem is modeled using the shallow-water approximation and the governing equations are solved using shock capturing schemes. The governing equations were discretized using both the l and flux vector splitting methods. The finite difference technique incorporates a numerical mapping so that the flow regime is transformed to a regular domain for numerical integration. These methods were applied for the simulation of a thin film flowing radially outward on a stationary disk. In this formulation, a first-order forward difference approximation for the time derivative was used. The results showed the location of the hydraulic jump could be predicted. Among the advantages of the non-staggered grid fractional step method are: the accuracy is second order in space and time, it can handle three-dimensional problems in complex geometries such as flows that turn 90°, it is possible to perform large eddy simulations and to implement turbulent models, and because of local orthogonality at the surface, melting problems can be studied with this method. The flux vector splitting technique can be used to analyze thin films with singularities present in the flow field.

Pacheco, Jose Rafael

1999-09-01

93

Attenuation and penetration of pulsed supersonic liquid jets---An experimental study  

Microsoft Academic Search

Pulsed supersonic liquid (water and diesel fuel) jets in the range of 1500 m\\/s to 1800 m\\/s have been produced and examined. A two stage light gas gun was used as a launcher to obtain the pulsed impact (velocity of 700m\\/s). In this paper, experimental results on the attenuation and the penetration distance of the liquid jets is presented. It

K. Pianthong; K. Takayama; B. E. Milton; M. Behnia

2005-01-01

94

Newly described hydrodynamic breakup modes of liquid-gas co-flowing jets  

Microsoft Academic Search

An inviscid, linear stability analysis of a liquid jet and the co-flowing gas stream surrounding the jet has been performed. The basic liquid and gas velocity profiles have been self-consistently obtained from the boundary layer type incompressible N-S equations. The analysis recovers the classical Rayleigh and Weber non-viscous results as limiting cases for well developed and very thin boundary layers

Jose M. Gordillo; Miguel Perez-Saborid; Alfonso M. Ganan-Calvo

2000-01-01

95

A Two-Phase LES Compressible Model for Plasma-Liquid Jet Interaction  

Microsoft Academic Search

\\u000a The numerical simulation of the interaction between a plasma flow and a liquid jet is important for understanding and predicting\\u000a the physical parameters involved in plasma spraying processes. This work proposes an original model for dealing with three-dimensional\\u000a and unsteady turbulent interactions between a plasma flow and a liquid water jet. A compressible model, based on augmented\\u000a Lagrangian, Large Eddy

Céline Caruyer; Stéphane Vincent; Erick Meillot; Jean-Paul Caltagirone

96

Wave packet analysis and break-up length calculations for an accelerating planar liquid jet  

NASA Astrophysics Data System (ADS)

This paper examines the process of transition to turbulence within an accelerating planar liquid jet. By calculating the propagation and spatial evolution of disturbance wave packets generated at a nozzle where the jet emerges, we are able to estimate break-up lengths and break-up times for different magnitudes of acceleration and different liquid to air density ratios. This study uses a basic jet velocity profile that has shear layers in both air and the liquid either side of the fluid interface. The shear layers are constructed as functions of velocity which behave in line with our CFD simulations of injecting diesel jets. The non-dimensional velocity of the jet along the jet centre-line axis is assumed to take the form V (t) = tanh(at), where the parameter a determines the magnitude of the acceleration. We compare the fully unsteady results obtained by solving the unsteady Rayleigh equation to those of a quasi-steady jet to determine when the unsteady effects are significant and whether the jet can be regarded as quasi-steady in typical operating conditions for diesel engines. For a heavy fluid injecting into a lighter fluid (density ratio ?air/?jet = q < 1), it is found that unsteady effects are mainly significant at early injection times where the jet velocity profile is changing fastest. When the shear layers in the jet thin with time, the unsteady effects cause the growth rate of the wave packet to be smaller than the corresponding quasi-steady jet, whereas for thickening shear layers the unsteady growth rate is larger than that of the quasi-steady jet. For large accelerations (large a), the unsteady effect remains at later times but its effect on the growth rate of the wave packet decreases as the time after injection increases. As the rate of acceleration is reduced, the range of velocity values for which the jet can be considered as quasi-steady increases until eventually the whole jet can be considered quasi-steady. For a homogeneous jet (q = 1), the range of values of a for which the jet can be considered completely quasi-steady increases to larger values of a. Finally, we investigate approximating the wave packet break-up length calculations with a method that follows the most unstable disturbance wave as the jet accelerates. This approach is similar to that used in CFD simulations as it greatly reduces computational time. We investigate whether or not this is a good approximation for the parameter values typically used in diesel engines.

Turner, M. R.; Healey, J. J.; Sazhin, S. S.; Piazzesi, R.

2012-02-01

97

Cryogenic liquid-jet breakup in two-fluid atomizers  

NASA Technical Reports Server (NTRS)

A two-fluid atomizer was used to study the breakup of liquid-nitrogen jets in nitrogen, argon, and helium atomizing gas flows. A scattered-light scanner particle sizing instrument previously developed at NASA Lewis Research Center was further developed and used to determine characteristic drop diameters for the cryogenic sprays. In the breakup regime of aerodynamic-stripping, i.e., sonic-velocity conditions, the following correlation of the reciprocal Sauter mean diameter, D(sub 32)exp -1, with the atomizing-gas flowrate, W(g), was obtained: D(sub 32)exp -1 = k(sub c)(W(g)exp 1.33), where k(sub c) is a proportionality constant evaluated for each atomizing gas. Values of k(sub c) = 120, 220, and 1100 were obtained for argon, nitrogen, and helium gasflows, respectively. The reciprocal Sauter mean diameter and gas flowrate have the units of 1/cm and g/sec, respectively. In the regime of capillary-wave breakup, or subsonic conditions, it was found that D(sub 32)exp -1 = k(g)(W(g)exp 0.75), where k = 270, 390, and 880 for argon, nitrogen, and helium gasflows, respectively.

Ingebo, Robert D.

1991-01-01

98

Attenuation and penetration of pulsed supersonic liquid jets—An experimental study  

NASA Astrophysics Data System (ADS)

Pulsed supersonic liquid (water and diesel fuel) jets in the range of 1500 m/s to 1800 m/s have been produced and examined. A two stage light gas gun was used as a launcher to obtain the pulsed impact (velocity of 700m/s). In this paper, experimental results on the attenuation and the penetration distance of the liquid jets is presented. It was found that the attenuation is relatively high in the first 300 ?s of the jet flight. The penetration distance is around 300-500 mm, this depending on the initial velocity, the nozzle geometry and the properties of liquid. The experimental results agree well with the estimation using conventional diesel spray formula. The shadowgraph image shows bow shock wave structures with multiple pulses which tend to enhance atomization and combustion. However, further examination of their atomization related to the jet attenuation and penetration distance is needed.

Pianthong, K.; Takayama, K.; Milton, B. E.; Behnia, M.

99

Deformation, wave phenomena, and breakup outcomes of round nonturbulent liquid jets in uniform gaseous crossflow  

NASA Astrophysics Data System (ADS)

Scope and method of study. An experimental and computational research is performed to study the deformation and breakup of round nonturbulent liquid jets in uniform gaseous crossflow. Pulsed photography and shadow graphy in conjunction with high-speed imaging were used to study the wave phenomena and the droplets properties/transport dynamics of a nonturbulent liquid jet injected into a uniform crossflow within the bag breakup regime. The computational study extended the previous two-dimensional study by adding the third dimension, allowing the wave properties to be modeled. The computational simulation employed the Volume of Fluid (VOF) formulation of FLUENT, and was run on a 3-processors parallel Linux cluster and P4 desktops. The validated, time-accurate, CFD simulation analyzes the surface properties of the liquid jets within the column, bag, and shear breakup regimes by considering the effects of surface tension, liquid viscosity, and crossflow Weber number at large liquid/gas density ratios (>500) and small Ohnesorge numbers (<0.1). Findings and conclusions. Present experimental results show that the column waves along the liquid jet are attributed to Rayleigh-Taylor instabilities and the nodes layout per bag affected the breakup mechanisms of the bags. Three distinctive sizes of droplets were produced in the bag breakup regime. The size of bag-droplets normalized by the nozzle exit diameter was constant. The different trajectories for bag- and node-droplets suggested that separation of bag- and node-droplets is possible. The computational results included jet deformations, jet cross-sectional area, jet velocity, wake velocity defect, wake width, and wavelengths of column and surface waves. Present computational results yielded a similarity solution for the inner wake region. In bag breakup, the lower pressure along the sides of the jet pulled the liquid away from both the upwind and downwind surfaces of the liquid cross-section. In shear breakup, the flattened upwind surface pushed the liquid towards the two sides of the jet. In bag breakup, the flow field inside the liquid jet consisted of a counter-rotating vortex pair that was not observed in column and shear breakup. Finally, phenomenological analyses were effective to understand the conditions for breakup regime transitions.

Ng, Chee-Loon

100

Production of Jet Fuels from Coal-Derived Liquids. Volume 13. Evaluation of Storage and Thermal Stability of Jet Fuels Derived from Coal Liquids.  

National Technical Information Service (NTIS)

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory of WPAFB, OH, began an investigation of the potential of the production of jet fuel from the liquid by-products streams produced by the gasification of lignite at the Great Plains Gasif...

G. P. Sturm R. D. Grigsby J. W. Goetzinger J. B. Green R. P. Anderson

1990-01-01

101

Analytical description of the breakup of liquid jets in air  

NASA Technical Reports Server (NTRS)

A viscous or inviscid cylindrical jet with surface tension in a vacuum tends to pinch due to the mechanism of capillary instability. Similarity solutions are constructed which describe this phenomenon as a critical time is encountered, for two physically distinct cases: inviscid jets governed by the Euler equations and highly viscous jets governed by the Stokes equations. In both cases the only assumption imposed is that at the time of pinching the jet shape has a radial length scale which is smaller than the axial length scale. For the inviscid case, we show that our solution corresponds exactly to one member of the one-parameter family of solutions obtained from slender jet theories and the shape of the jet is locally concave at breakup. For highly viscous jets our theory predicts local shapes which are monotonic increasing or decreasing indicating the formation of a mother drop connected to the jet by a thin fluid tube. This qualitative behavior is in complete agreement with both direct numerical simulations and experimental observations.

Papageorgiou, Demetrios T.

1993-01-01

102

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Task 1 of the work, in which processes to produce each of the three jet

M. W. Furlong; J. D. Fox; J. G. Masin; D. J. Soderberg

1988-01-01

103

Production of jet fuels from coal-derived liquids  

Microsoft Academic Search

A preliminary design for the production of JP-8 jet fuel and other salable products from the Great Plains by-products is given. The design incorporates experimental results from Tasks 2 and 3 with the scoping design from Task 1. The experimental results demonstrated the need for more severe hydrotreating conditions to convert the tar oil to jet fuel than was estimated

M. Furlong; J. Fox; J. Masin; E. Stahlnecker; G. Schreiber; R. Klein

1989-01-01

104

Quantitative determination of wear metals in engine oils using laser-induced breakdown spectroscopy: A comparison between liquid jets and static liquids  

Microsoft Academic Search

A comparison of laser-induced breakdown spectroscopy (LIBS) sensitivity in laminar liquid jets and at the surface of a static liquid has been performed. Limits of detection (LODs) have been estimated for Na, Mg, Al, Ca, Ti, V, Cr, Mn, Ni, Fe, Cu, Zn, Mo, Ag, Cd, and Ba under similar conditions using both experimental arrangements. LODs in liquid jets are

Pavel Yaroshchyk; Richard J. S. Morrison; Doug Body; Bruce L. Chadwick

2005-01-01

105

Excitation of electrohydrodynamic surface waves on a conducting liquid jet employing AC field  

Microsoft Academic Search

A method of exciting waves on the surface of a conducting liquid jet by means of time varying electric field is presented. The prime objective of employing such a technique is to produce, electrostatically, a monodisperse spray of highly conducting liquid, in a controlled manner. This method relies on the use of an AC field in a certain frequency range

Z. Huneiti; W. Machowski; W. Balachandran

1996-01-01

106

A hydrodynamic model for subcooled liquid jet impingement at the Leidenfrost condition  

Microsoft Academic Search

Stable film boiling occurs in the stagnation region of an impinging subcooled liquid jet during quenching of very hot steel plates. During film boiling the liquid is separated from the surface of the plate by a continuous vapor layer. The minimum surface temperature required to support film boiling is referred to as the Leidenfrost temperature. The present work is devoted

Nitin Karwa; Tatiana Gambaryan-Roisman; Peter Stephan; Cam Tropea

2011-01-01

107

Electrohydrodynamic inter-electrode flow and liquid jet characteristics in charge injection atomizers  

NASA Astrophysics Data System (ADS)

The governing equations of electrohydrodynamics pertinent to forced and free electroconvection have been examined in the context of an array of charge injection atomization systems for dielectric electrically insulating liquids. The underlying physics defining their operation has been described further by linking the internal charge injection process inside the atomizer with resulting charged liquid jet characteristics outside it. A new nondimensional number termed the electric jet Reynolds number Re E,j is required to describe charge injection systems universally. The electric jet Reynolds number Re E,j varies linearly with the inter-electrode gap electric Reynolds number Re E, and the inter-electrode gap Reynolds number Re E varies linearly with the conventional liquid jet Reynolds number Re j. These variations yield two new seemingly universal constants relevant in the description of two-phase charge injection systems. The first constant being which physically represents the ratio of jet to inter-electrode gap electric field multipled by a nondimensional geometric factor while it may also be physically seen as a forced flow charge injection strength term, analogous to the `C' term described in single-phase free electroconvection. The second constant being which physically represents the ratio of inter-electrode gap ionic drift velocity, to the liquid jet velocity, multipled by a nondimensional geometric factor. These scalings have been found to be valid for charge injection systems regardless of fuel, voltage pulsation, electrode shape, orifice diameter, and inter-electrode gap length.

Kourmatzis, A.; Shrimpton, J. S.

2014-03-01

108

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Conceptual processing schemes for maximizing the production of Grades JP-4, JP-8, and high-density (JP-8X) jet

M. W. Furlong; J. D. Fox; J. G. Masin; D. J. Soderberg

1990-01-01

109

Unsteady penetration of a target by a liquid jet  

PubMed Central

It is widely acknowledged that ceramic armor experiences an unsteady penetration response: an impacting projectile may erode on the surface of a ceramic target without substantial penetration for a significant amount of time and then suddenly start to penetrate the target. Although known for more than four decades, this phenomenon, commonly referred to as dwell, remains largely unexplained. Here, we use scaled analog experiments with a low-speed water jet and a soft, translucent target material to investigate dwell. The transient target response, in terms of depth of penetration and impact force, is captured using a high-speed camera in combination with a piezoelectric force sensor. We observe the phenomenon of dwell using a soft (noncracking) target material. The results show that the penetration rate increases when the flow of the impacting water jet is reversed due to the deformation of the jet–target interface––this reversal is also associated with an increase in the force exerted by the jet on the target. Creep penetration experiments with a constant indentation force did not show an increase in the penetration rate, confirming that flow reversal is the cause of the unsteady penetration rate. Our results suggest that dwell can occur in a ductile noncracking target due to flow reversal. This phenomenon of flow reversal is rather widespread and present in a wide range of impact situations, including water-jet cutting, needleless injection, and deposit removal via a fluid jet.

Uth, Tobias; Deshpande, Vikram S.

2013-01-01

110

Unsteady penetration of a target by a liquid jet.  

PubMed

It is widely acknowledged that ceramic armor experiences an unsteady penetration response: an impacting projectile may erode on the surface of a ceramic target without substantial penetration for a significant amount of time and then suddenly start to penetrate the target. Although known for more than four decades, this phenomenon, commonly referred to as dwell, remains largely unexplained. Here, we use scaled analog experiments with a low-speed water jet and a soft, translucent target material to investigate dwell. The transient target response, in terms of depth of penetration and impact force, is captured using a high-speed camera in combination with a piezoelectric force sensor. We observe the phenomenon of dwell using a soft (noncracking) target material. The results show that the penetration rate increases when the flow of the impacting water jet is reversed due to the deformation of the jet-target interface--this reversal is also associated with an increase in the force exerted by the jet on the target. Creep penetration experiments with a constant indentation force did not show an increase in the penetration rate, confirming that flow reversal is the cause of the unsteady penetration rate. Our results suggest that dwell can occur in a ductile noncracking target due to flow reversal. This phenomenon of flow reversal is rather widespread and present in a wide range of impact situations, including water-jet cutting, needleless injection, and deposit removal via a fluid jet. PMID:24277818

Uth, Tobias; Deshpande, Vikram S

2013-12-10

111

Hydrocarbon group type determination in jet fuels by high performance liquid chromatography  

NASA Technical Reports Server (NTRS)

Thirty-two jet and diesel fuel samples of varying chemical composition and physical properties were prepared from oil shale and coal syncrudes. Hydrocarbon types in these samples were determined by a fluorescent indicator adsorption analysis, and the results from three laboratories are presented and compared. Two methods of rapid high performance liquid chromatography were used to analyze some of the samples, and these results are also presented and compared. Two samples of petroleum-based Jet A fuel are similarly analyzed.

Antoine, A. C.

1977-01-01

112

Liquid jet impingement normal to a disk in zero gravity. Ph.D. Thesis - Toledo Univ.  

NASA Technical Reports Server (NTRS)

An experimental and analytical investigation was conducted to determine the free surface shapes of circular liquid jets impinging normal to sharp-edged disks under both normal and zero gravity conditions. An order of magnitude analysis was conducted indicating regions where viscous forces were not significant when computing free surface shapes. The demarcation between the viscous and inviscid region was found to depend upon the flow Reynolds number and the ratio between the jet and disk radius.

Labus, T. L.

1976-01-01

113

High-velocity liquid jet injection into tokamak plasmas for disruption mitigation  

SciTech Connect

Proposed is a new concept for disruption mitigation and fast shutdown in tokamaks: the injection of hydrogen or helium liquid jets. Liquid jets can rapidly cool the plasma to reduce divertor heat loads and large halo current forces while simultaneously raising the density sufficiently to prevent runaway electron generation. Massive [approximately]40- to 100-fold density increases equivalent to [approximately]50 g of deuterium are necessary for this purpose in the International Thermonuclear Experimental Reactor (ITER). It is shown that only two or three simultaneously injected high-velocity (800 to 1200 m/s) jets can easily deliver this amount of fuel within a period of [approximately]20 ms and thus avoid runaway electron buildup during the 50- to 500-ms current quench phase. Optimum jet parameters, such as radius, velocity, driving pressure, and injection time, predicted from a jet ablation/penetration model, lead to an innovative pulsed injector design concept. The design concept is also based on a thermodynamic process path that allows the lowest possible temperature at the nozzle orifice, given the constraint of a high, [approximately]700-atm driving pressure. By having a cold jet exit the nozzle orifice, the potential problem of rapid boiling (flashover) during jet propagation across vacuum space between the nozzle orifice and the tokamak plasma can be overcome. A one-dimensional fluid-dynamic calculation, including finite compressibility, shows that a specially designed liquid Laval nozzle is needed for liquid helium injection because the jet velocity is supersonic (Mach number [approximately]4). This injector concept is being considered for a proposed disruption mitigation experiment on DIII-D.

Parks, P.B.; Rosenbluth, M.N.; Putvinski, S.V.; Evans, T.E. (General Atomics, San Diego, CA (United States))

1999-05-01

114

Effect of mass-velocity on liquid jet atomization in Mach 1 gasflow  

NASA Technical Reports Server (NTRS)

Interacting two-phase flow in four differently sized pneumatic two-fluid atomizers was investigated to determine the effect of gas mass-velocity on the Sauter mean diameter of sprays produced by small diameter liquid jets breaking up in high velocity gas flow. Tests were conducted primarily in the acceleration-wave regime for liquid jet atomization, where it was found that the loss of droplets due to vaporization had a marked effect on drop size measurements. A scattered-light scanner, developed at NASA Lewis Research Center, was used to measure the Sauter mean diameter, D sub 32, which was correlated with nitrogen gas mass-velocity to give the following expression: D (sup -1)(sub 32) = 11.7(rho (sub n) V (sub n)) (sup 1.33). The exponent 1.33 for the gas mass-velocity is identical to that predicted by atomization theory for liquid jet breakup in the acceleration-wave regime.

Ingebo, Robert D.

1988-01-01

115

Absolute And Convective Instability and Splitting of a Liquid Jet at Microgravity  

NASA Technical Reports Server (NTRS)

The objective is to establish a definitive role of the capillary, viscous, and inertial forces at a liquid-gas interface in the absence of gravity by using the fluid dynamics problem of the stability of a liquid jet as a vehicle. The objective is achieved by reexamining known theories and new theories that can be verified completely only in microgravity. The experiments performed in the microgravity facility at NASA Glenn Research Center enable the verification of the theory with experimental data. Of particular interest are (1) to capture for the first time the image of absolute instability, (2) to elucidate the fundamental difference in the physical mechanism of the drop and spray formation from a liquid jet, and (3) to find the origin of the newly discovered phenomenon of jet splitting on earth and in space.

Lin, S. P.

2001-01-01

116

Investigation of pure- and aerated-liquid jets using ultra-fast X-ray phase contrast imaging  

Microsoft Academic Search

Pure- and aerated-liquid jets were observed using the ultra-fast X-ray phase contrast imaging technique. Highly convoluted wrinkle structures were seen on the column surface of a turbulent pure-liquid jet, gas bubbles were discovered inside droplets and ligaments of aerated-liquid sprays, and apparently homogenous two-phase mixtures were observed inside the aerated-liquid injector. The major limitation of this X-ray technique lies in

Kuo-Cheng Lin; Christopher Rajnicek; Jonathan McCall; Campbell Carter; Kamel Fezzaa

2011-01-01

117

Laser cutting of silicon with the liquid jet guided laser using a chlorine-containing jet media  

NASA Astrophysics Data System (ADS)

In this paper results for liquid media are presented, which are used the first time as liquid jet for cutting of silicon with laser chemical processing (LCP). The liquids contain a perfluoro-carbon compound as solvent and elemental chlorine as etching agent for silicon. Experiments were performed to investigate its influence on groove form and maximum achieved groove depth. It is shown that with the addition of low-concentration chlorine, the groove depth can already be significantly increased. The groove shape could be changed from a V-profile to a U-profile. Furthermore, an about four times greater groove depth was achieved by applying a saturated chlorine solution compared to groove depths without using chlorine. Finally, a theory is given and discussed to describe the phenomena observed.

Hopman, Sybille; Mayer, Kuno; Fell, Andreas; Mesec, Matthias; Granek, Filip

2011-03-01

118

Air Ingestion by a Buckled Viscous Jet of Silicone Oil Impacting the Free Surface of the Same Liquid  

NASA Astrophysics Data System (ADS)

As frequently observed in common life, a jet of a viscous liquid impacting on a horizontal surface does not remain straight but instead buckles and folds periodically. We report experiments with planar (ribbonlike) jets of silicone oil impacting the free surface of the same liquid and describe the way in which jet folds incorporate air. It is shown that air ingestion proceeds through different modes, each of them acting as a source of monodisperse bubbles and featuring a threshold in jet height. These sources result from the breakup of remarkable cuspidal structures, produced by the recession of air domains within liquid folds.

Pouligny, B.; Chassande-Mottin, M.

2008-04-01

119

Air ingestion by a buckled viscous jet of silicone oil impacting the free surface of the same liquid.  

PubMed

As frequently observed in common life, a jet of a viscous liquid impacting on a horizontal surface does not remain straight but instead buckles and folds periodically. We report experiments with planar (ribbonlike) jets of silicone oil impacting the free surface of the same liquid and describe the way in which jet folds incorporate air. It is shown that air ingestion proceeds through different modes, each of them acting as a source of monodisperse bubbles and featuring a threshold in jet height. These sources result from the breakup of remarkable cuspidal structures, produced by the recession of air domains within liquid folds. PMID:18518112

Pouligny, B; Chassande-Mottin, M

2008-04-18

120

The effect of chemical reaction on liquid round free jet  

Microsoft Academic Search

In the fluid engineering field, chemical reaction frequently occur. Sodium-water chain reaction in the sodium cooled nuclear reactor can make an explosion that causes the accident during the operation of nuclear reactor. Therefore, it is very important to investigate the characteristic of this chemically reacting type of jet to achieve the reliable design of industrial reactor. Although a number of

Seong Dae Hong; Okamoto Koji; Madarame Haruki

2002-01-01

121

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus Crest are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Analytical characterizations of these three by-products indicate the range of products that can be manufactured from each, and potential problems which could be encountered during

M. W. Furlong; J. D. Fox; J. G. Masin; D. J. Soderberg

1987-01-01

122

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Analytical characterizations of these three by-products indicate the range of products that can be manufactured

M. W. Furlong; J. D. Fox; J. G. Masin

1988-01-01

123

The Plunge Phase of Friction Stir Welding  

NASA Technical Reports Server (NTRS)

The many advantages of Friction Stir Welding have led to a relatively rapid acceptance in the often conservative welding community. Because the process is so different from traditional fusion welding, with which most investigators are most familiar, there remain many aspects of FSW for which there is no clear consensus. For example, the well known onion rings seen in transverse sections have been variously interpreted as grain size variations, variation in density of second phase particles and parts of the carousel of material rotating with the pin that have been shed from the carousel. Using Orientation Imaging Microscopy, Schneider has recently noted that the onion rings have a different orientation (and hence etch differently) than the surrounding material, and this orientation is consistent with slip plane orientations at the edge of the carousel. Likewise, the forces and torque exerted by the FSW tool on the work piece largely remain unaccounted for. Although these forces are routinely measured by investigators with commercial instrumented welders, they are rarely reported or even qualitatively analyzed. This paper will introduce a model based on a carousel or disk of material that rotates with the tool to estimate the torque and plunge force required to plunge a tool into the work piece. A stationary tool is modeled rather than the moving tool because effects such as thermal transients and metallurgical changes in the sample (primarily aging in aluminum) can be more easily accounted for. It is believed, however, that with some modifications the model should be applicable to a moving tool also.

McClure, John C.

2005-01-01

124

Flow of a two-dimensional liquid metal jet in a strong magnetic field.  

SciTech Connect

Two-dimensional, steady flow of a liquid metal slender jet pouring from a nozzle in the presence of a transverse, nonuniform magnetic field is studied. The surface tension has been neglected, while gravity is shown to be not important. The main aim of the study is to evaluate the importance of the inertial effects. It has been shown that for gradually varying fields characteristic for the divertor region of a tokamak, inertial effects are negligible for N > 10, where N is the interaction parameter. Thus the inertialess flow model is expected to give good results even for relatively low magnetic fields and high jet velocity. Simple relations for the jet thickness and velocity have been derived. The results show that the jet becomes thicker if the field increases along the flow and thinner if it decreases.

Reed, C.B.; Molokov, S.

2002-02-22

125

Application of underwater shock wave and laser-induced liquid jet to neurosurgery  

NASA Astrophysics Data System (ADS)

Paper deals with applications of underwater shock waves to medicine. A historical development of underwater shock wave generation by using pulsed Ho:YAG laser beam irradiation in water is briefly described and an overview is given regarding potential applications of shock waves to neuro-surgery. The laser beam irradiation in a liquid-filled catheter produces water vapor bubble and shock waves intermittently produces micro-liquid jets in a controlled fashion from the exit of the catheter. Correlations between shock dynamics and bubble dynamics are emphasized. To optimize the jet motion, results of basic parametric studies are briefly presented. The liquid jet discharged from the catheter exit has an impulse high enough to clearly exhibit effectiveness for various medical purposes. In liquid jets we observed reasonably strong shock waves and hence invented a compact shock generator aiming to apply to microsurgery. We applied it to a rat's bone window and developed an effective method of brain protection against shock loading. The insertion of Gore-Tex® sheet is found to attenuate shock waves drastically even for very short stand off distance and its physical mechanism is clarified. The laser-induced liquid jet (LILJ) is successfully applied to soft tissue dissection. Animal experiments were performed and results of histological observations are presented in details. Results of animal experiments revealed that LILJ can sharply dissect soft tissue with a minimum amount of liquid consumption, while blood vessels larger than 0.2 mm in diameter are preserved. Shock waves and LILJ have a potential to be indispensable tools in neuro-surgery.

Tominaga, T.; Nakagawa, A.; Hirano, T.; Sato, J.; Kato, K.; Hosseini, S. H. R.; Takayama, K.

2006-03-01

126

A linear spatial stability analysis of liquid-gas rotating co-flowing jet  

Microsoft Academic Search

We present a linear spatial stability analysis of a liquid-gas rotating co-flowing jet. The parallel mean velocity is computed as a function of the radial coordinate by solving the coupled liquid-gas Navier-Stokes equations in a cylindrical coordinate system. A multi-domain Chebyshev spectral collocation method is applied to the perturbed Navier-Stokes equations (linearized about the mean parallel flow). Both axisymmetric and

Yaohong Wang; Mark Sussman; M. Y. Hussaini

2009-01-01

127

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus-Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Analytical characterizations of these three by-products indicate the range of products that can be manufactured from

M. W. Furlong; J. D. Fox; J. G. Masin

1989-01-01

128

Production of jet fuel from coal-derived liquids  

Microsoft Academic Search

Amoco and Lummus-Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet fuels and other salable products. Analytical characterizations of these three by-products indicate the range of products that can be manufactured from

M. W. Furlong; J. D. Fox; J. G. Masin

1988-01-01

129

A Particle-Tracking-Velocimetry (PTV) Investigation of Liquid Injection in a DC Plasma Jet  

NASA Astrophysics Data System (ADS)

The present article describes experimental results of liquid injection in a thermal plasma jet by particle-tracking velocimetry (PTV). This technique delivers an in-situ real-time analysis of the liquid breakup and measures the velocities and the trajectories of the particles. The observations were done within the 10 mm surrounding the injection location where the plasma brightness is considerable. First, a validation of the proposed investigation method was carried out in a slower plasma jet. Subsequently, PTV measurements within faster plasma jets, resulting in a set of trajectories, were compared with trajectories achieved through optical diagnostics based on a simple shadow-graph technique proposed by Damiani et al. [Injection d'un liquide au sein d'un jet plasma thermique: optimisation de la trajectoire des particules, Proceedings of Congrès Francophone de Techniques Laser, CFTL 2010, Vandoeuvre lès nancy, France, 2010 (in French)]. These trajectories indicated that a higher plasma flow rate was required to spray all droplet sizes in the axis of the flow, thereby enabling an optimal spraying (then coating) application for producing nanostructured thin layers. This study showed that the liquid injection parameters are of main importance to obtain optimal injection and plasma parameters to achieve the required coating properties.

Damiani, David; Tarlet, Dominique; Meillot, Erick

2014-02-01

130

Self-organization of jets in electrospinning from free liquid surface: A generalized approach  

Microsoft Academic Search

Electrospinning has enabled creation of excellent materials for a great number of applications. Previously, it was based on less productive capillary spinners. The present study is based on recent efforts to elevate electrospinning technology to an industrial level by simultaneously provoking innumerable polymeric jets from a sufficiently large liquid surface to increase productivity. Particularly, it deals with electrospinning from free

David Lukas; Arindam Sarkar; Pavel Pokorny

2008-01-01

131

A new technology for revascularization of cerebral embolism using liquid jet impact  

NASA Astrophysics Data System (ADS)

Revascularization time is the dominant factor in the treatment of acute cerebral embolism. In this paper we describe a rapid revascularization therapy using liquid jets generated by the interaction of gas bubbles with shock waves, which impact on the thrombi. The interaction of a shock wave with a gas bubble attached to an artificial thrombus which was inserted into a tube model of a cerebral artery was investigated. The shock wave was generated by detonating a microexplosive pellet. The overpressure of the shock wave was (n = 7) and (n = 3). The initial air bubble radii were varied from 0.87 mm to 2.18 mm. The subsequent collapse of the bubble was photographed using a high-speed framing camera, and the liquid jet penetrating into the artificial thrombus was visualized using x-ray photography. The penetration depth of the liquid jet increased with increasing bubble size. There was an optimal separation distance between the bubble and the shock wave source to obtain the maximum penetration depth. Liquid jets have the potential to penetrate through thrombi in as little as a few microseconds, and with very efficient ablation.

Kodama, Tetsuya; Takayama, Kazuyoshi; Uenohara, Hiroshi

1997-12-01

132

Acoustic excitation of liquid fuel droplets and coaxial jets  

Microsoft Academic Search

This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the

Juan Ignacio Rodriguez

2009-01-01

133

Experimental investigation of inclined liquid water jet flow onto vertically located superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

In this study, the behaviour of an inclined water jet, which is impinged onto hydrophobic and superhydrophobic surfaces, has been investigated experimentally. Water jet was impinged with different inclination angles (15°-45°) onto five different hydrophobic surfaces made of rough polymer, which were held vertically. The water contact angles on these surfaces were measured as 102°, 112°, 123°, 145° and 167° showing that the last surface was superhydrophobic. Two different nozzles with 1.75 and 4 mm in diameters were used to create the water jet. Water jet velocity was within the range of 0.5-5 m/s, thus the Weber number varied from 5 to 650 and Reynolds number from 500 to 8,000 during the experiments. Hydrophobic surfaces reflected the liquid jet depending on the surface contact angle, jet inclination angle and the Weber number. The variation of the reflection angle with the Weber number showed a maximum value for a constant jet angle. The maximum value of the reflection angle was nearly equal to half of the jet angle. It was determined that the viscous drag decreases as the contact angle of the hydrophobic surface increases. The drag force on the wall is reduced dramatically with superhydrophobic surfaces. The amount of reduction of the average shear stress on the wall was about 40%, when the contact angle of the surface was increased from 145° to 167°. The area of the spreading water layer decreased as the contact angle of the surface increased and as the jet inclination angle, Weber number and Reynolds number decreased.

Kibar, Ali; Karabay, Hasan; Yi?it, K. Süleyman; Ucar, Ikrime O.; Erbil, H. Y?ld?r?m

2010-11-01

134

Jets.  

PubMed

This is a discussion of concentrated large-scale flows in planetary atmospheres and oceans, argued from the viewpoint of basic geophysical fluid dynamics. We give several elementary examples in which these flows form jets on rotating spheres. Jet formation occurs under a variety of circumstances: when flows driven by external stress have a rigid boundary which can balance the Coriolis force, and at which further concentration can be caused by the beta effect; when there are singular lines like the line of vanishing windstress or windstress-curl, or the Equator; when compact sources of momentum, heat or mass radiate jet-like beta plumes along latitude circles; when random external stirring of the fluid becomes organized by the beta effect into jets; when internal instability of the mass field generates zonal flow which then is concentrated into jets; when bottom topographic obstacles radiate jets, and when frontogenesis leads to shallow jet formation. Essential to the process of jet formation in stratified fluids is the baroclinic life cycle described in geostrophic turbulence studies; there, conversion from potential to kinetic energy generates eddy motions, and these convert to quasibarotropic motions which then radiate and induce jet-like large-scale circulation. Ideas of potential vorticity stirring by eddies generalize the notion of Rossby-wave radiation, showing how jets embedded in an ambient potential vorticity gradient (typically due to the spherical geometry of the rotating planet) gain eastward momentum while promoting broader, weaker westward circulation. Homogenization of potential vorticity is an important limit point, which many geophysical circulations achieve. This well-mixed state is found in subdomains of the terrestrial midlatitude oceans, the high-latitude circumpolar ocean, and episodically in the middle atmosphere. Homogenization expels potential vorticity gradients vertically to the top and bottom of the fluid, and sideways to the edges of flow domains or gyres; in both these ways is jet formation enhanced. PMID:12780108

Rhines, Peter B.

1994-06-01

135

First Results of the Testing of the Liquid Gallium Jet Limiter Concept for ISTTOK  

NASA Astrophysics Data System (ADS)

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium jet is generated by hydrostatic pressure and injected in a radial position close to a moveable stainless steel limiter. Both the jet and the limiter positions are variable allowing for a controlled exposure of the liquid Gallium to the edge plasma. The main components of the Gallium loop are a MHD pump, the liquid metal injector and a filtering system. The MHD pump is of the induction type, based on rotating permanent magnets. The injector is build from a ¼'' stainless steel pipe ended by a shaping nozzle. A setup has been developed to introduce oxide-free Gallium inside the loop's main supply tank. Raw liquid metal is placed inside a chamber heated and degassed under high vacuum while clean Gallium is extracted from the main body of the liquefied metal. Prior to installation on the tokamak, the experimental rig has been implemented using a Pyrex tube as test chamber to investigate the stability of the Gallium jet and its break-up length for several nozzle sizes. Results are presented in this paper. This rig was also useful to assess the behavior of the overall implemented apparatus.

Gomes, R. B.; Fernandes, H.; Silva, C.; Borba, D.; Carvalho, B.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I.

2006-12-01

136

Hydraulic Characteristics of a Plunge Zone in Whiskeytown Reservoir, California  

Microsoft Academic Search

1. Abstract This paper presents field tests that were conducted to determine the hydraulic characteristics of a plunge zone. The field tests were carried out in Whiskeytown Reservoir which is part of the US Bureau of Reclamation's (Reclamation) Central Valley Project in northern California. Plunging inflows occur when cold water diverted from an upstream reservoir is discharged through a powerplant

Tracy Vermeyen; Helmut Knoblauch

137

Production of jet fuels from coal-derived liquids  

SciTech Connect

A preliminary design for the production of JP-8 jet fuel and other salable products from the Great Plains by-products is given. The design incorporates experimental results from Tasks 2 and 3 with the scoping design from Task 1. The experimental results demonstrated the need for more severe hydrotreating conditions to convert the tar oil to jet fuel than was estimated in Task 1. As a result, capital costs for the revised design are significantly higher and the plant is less profitable than estimated in the Task 1 work. The increase in capital costs is offset somewhat by a higher phenol value in the current market. Refined estimates for the cost of an aromatics recovery unit preclude its economical construction in the new estimate, consequently the revised product slate includes no BTX. Recommendations are given for a 10,000 barrel production run. No commercial domestic facility exists which can provide suitable expanded-bed hydrotreating facilities for a production run of this size. However, an alternative approach using hot filtration and dilute fixed-bed hydrocracking followed by product fractionation and extinctive hydrotreating of the heavy products is recommended. Commercial domestic facilities which might reasonably accommodate this scheme are listed. 6 refs., 8 figs., 11 tabs.

Furlong, M.; Fox, J.; Masin, J. (Amoco Oil Co., Naperville, IL (USA). Research and Development Dept.); Stahlnecker, E.; Schreiber, G.; Klein, R. (Lummus Crest, Inc., Bloomfield, NJ (USA))

1989-12-01

138

Liquid Fuel Jet Injection into a Simulated Subsonic 'Dump' Combustor.  

National Technical Information Service (NTIS)

Basic experimental studies of the injection of liquid fuel into a two dimensional flowfield designed to represent a sudden-expansion 'dump' combustor were performed under cold-flow conditions. Test conditions were as follows: 0.6 entrance Mach number, 25 ...

J. C. Ogg J. A. Schetz

1979-01-01

139

Liquid jet breakup and atomization in rocket chambers under dense spray conditions  

NASA Technical Reports Server (NTRS)

Two advanced diagnostic techniques were established and employed in this project. The first technique involves the use of a real-time x ray radiography system along with a high-speed CCD Xybion camera and an advanced digital image processor to investigate the breakup processes of the liquid core. The focus of this part of the project is to determine the inner structure of the liquid jet and via thin sheets of laser light, with the scatters light being photographed by a Xybion electronic camera synchronized to the laser pulse. This technique, which is capable of recording the breakup event occurring within 25 nano-seconds, enables us to freeze the motions of the jet and liquid droplets. The focus of this part of the project is to determine the outer structure of the liquid jet and to discover the configuration of the surface waves, the spray pattern, and the droplet size distribution in the non-dilute region. Results obtained by these two advanced diagnostic techniques will provide the much needed database for model development and accurate prediction of engine performance. The present work also represents a breakthrough in the area of advanced diagnostics of dense sprays.

Kuo, Kenneth K.; Cheung, Fan-Bill; Woodward, Roger D.; Garner, Kenneth N.

1991-01-01

140

A microfocus x-ray source based on a nonmetal liquid-jet anode  

SciTech Connect

We demonstrate stable operation of a nonmetallic anode in an electron-impact x-ray source. A high-brightness electron beam is focused on a {approx}70 m/s speed, {approx}10 {mu}m diameter methanol jet producing stable x-ray emission with peak spectral brightness at {approx}5.4x10{sup 5} photons/(sx{mu}m{sup 2}xsrx0.1%BW). The jet is fully evaporated in the interaction point. The shape of a simulated spectrum using Monte Carlo methods shows good agreement with experimental data, and the theoretical brightness values give an upper limit for the achievable x-ray emission from jets with very high velocities. Using this anode concept, all compounds and elements found in liquid form are potentially usable for x-ray generation.

Tuohimaa, T.; Ewald, J.; Schlie, M.; Hertz, H. M.; Vogt, U. [Biomedical and X-ray Physics, Department of Applied Physics, KTH Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden); Fernandez-Varea, J. M. [Facultat de Fisica (ECM), Universitat de Barcelona, Diagonal 647, ES-08028 Barcelona (Spain)

2008-06-09

141

A 9 keV electron-impact liquid-gallium-jet x-ray source  

SciTech Connect

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A {approx}30 W, 50 kV electron gun is focused onto the {approx}20 m/s, 30 {mu}m diameter liquid-gallium-jet anode to produce an {approx}10 {mu}m full width at half maximum x-ray spot. The peak spectral brightness is >2x10{sup 10} photons/(s mm{sup 2} mrad{sup 2}x0.1% BW). Calculation and experiments show potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

Otendal, M.; Tuohimaa, T.; Vogt, U.; Hertz, H. M. [Biomedical and X-Ray Physics, Department of Applied Physics, Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden)

2008-01-15

142

The production of lithium oxide microspheres from the disintegration of a liquid jet  

Microsoft Academic Search

Microspheres of lithium hydroxide (LiOH) were produced from in-flight solidification of droplets formed by the disintegration of an acoustically driven, mechanically vibrated cylindrical liquid jet of molten LiOH. The molten material at 470 to 480°C was fed through a 25-gauge (0.0267-cm bore diameter) nozzle, interiorly electroplated with silver, under â¼27.6-kPa (4-psig) pressure, and at a mechanical vibration frequency of 10

M. R. Al-Ubaidi; J. N. Anno

1989-01-01

143

Periodically plunging foil near a free surface  

NASA Astrophysics Data System (ADS)

Experiments were performed to investigate the effects of amplitude and depth on the drag reduction of a NACA 0012 airfoil plunging near a free surface for a range of frequencies. Beyond the effect of the free surface, at low Strouhal numbers based on amplitude, Sr A, the drag reduction follows a parabolic trend with greater effect for greater amplitude, similar to the Garrick predictions. At Sr A ? 0.08, larger amplitudes break from this trend due to leading-edge vortex formation. As a result, smaller amplitudes become preferable for Sr A > 0.12. In addition, for the first time, vortex lock-in is documented experimentally. The effect of depth is twofold; firstly with decreasing depth, there is a general departure from the Garrick trends. Secondly, a reduction in thrust is observed around a constant unsteady parameter of ? = U ? 2 ?f/ g ? 0.25; around this value significant free-surface waves form that detract from thrust creation. For depths greater than two chord lengths, there is negligible free-surface effect.

Cleaver, D. J.; Calderon, D. E.; Wang, Z.; Gursul, I.

2013-03-01

144

Agreement between experimental and theoretical effects of nitrogen gas flowrate on liquid jet atomization  

NASA Technical Reports Server (NTRS)

Two-phase flows were investigated by using high velocity nitrogen gas streams to atomize small-diameter liquid jets. Tests were conducted primarily in the acceleration-wave regime for liquid jet atomization, where it was found that the loss of droplets due to vaporization had a marked effect on drop size measurements. In addition, four identically designed two-fluid atomizers were fabricated and tested for similarity of spray profiles. A scattered-light scanner was used to measure a characteristic drop diameter, which was correlated with nitrogen gas flowrate. The exponent of 1.33 for nitrogen gas flowrate is identical to that predicted by atomization theory for liquid jet breakup in the acceleration-wave regime. This is higher than the value of 1.2 which was previously obtained at a sampling distance of 4.4 cm downstream of the atomizer. The difference is attributed to the fact that drop-size measurements obtained at a 2.2 cm sampling distance are less effected by vaporization and dispersion of small droplets and therefore should give better agreement with atomization theory. Profiles of characteristic drop diameters were also obtained by making at least five line-of-sight measurements across the spray at several horizontal positions above and below the center line of the spray.

Ingebo, Robert D.

1987-01-01

145

Agreement between experimental and theoretical effects of nitrogen gas flowrate on liquid jet atomization  

NASA Technical Reports Server (NTRS)

Two-phase flows were investigated by using high velocity nitrogen gas streams to atomize small-diameter liquid jets. Tests were conducted primarily in the acceleration-wave regime for liquid jet atomization, where it was found that the loss of droplets due to vaporization had a marked effect on drop-size measurements. In addition, four identically designed two-fluid atomizers were fabricated and tested for similarity of spray profiles. A scattered-light scanner was used to measure a characteristic drop diameter, which was correlated with nitrogen gas flowrate. The exponent of 1.33 for nitrogen gas flowrate is identical to that predicted by atomization theory for liquid jet breakup in the acceleration-wave regime. This is higher than the value of 1.2 which was previously obtained at a smapling distance of 4.4 cm downstream of the atomizer. The difference is attributed to the fact that drop-size measurements obtained at a 2.2 cm sampling distance are less affected by vaporization and dispersion of small droplets and therefore should give better agreement with atomization theory. Profiles of characteristic drop diameters were also obtained by making at least five line-of-sight measurements across the spray at several horizontal positions above and below the center line of the spray.

Ingebo, Robert D.

1987-01-01

146

An optimization scheme for the measurement of liquid jet parameters with rainbow refractometry based on Debye theory  

NASA Astrophysics Data System (ADS)

Rainbow refractometry can be used to measure the radius and refractive index of a liquid jet. However, most existing algorithms are based on Airy theory or empirical formula from the angular spectrum of the rainbow. To apply the Airy formula, some characteristic information relevant to the radius and refractive index should be properly extracted from the rainbow. This is challenging for the liquid jet radius changing in a wide range because the rainbow structure, especially the ripple structure, is affected by the noise and the cone effect of a practical liquid jet. In this paper, a novel optimization scheme for the measurement of liquid jet parameters based on Debye theory (p=2) is proposed. First, an objective function is designed to quantify the deviation between the simulated rainbow with Debye theory (p=2) and the rainbow captured by a CCD camera. The liquid jet parameters are then determined by optimizing the objective function value. Experiments and numerical simulations are performed to evaluate the effectiveness of the scheme. Results indicate that the relative error of the radius is less than 12% and the absolute error of the refractive index is better than 1.1×10-3 when the real radius of the liquid jet is 25 ?m. The measurement accuracy increases with the radius.

Song, Feihu; Xu, Chuanlong; Wang, Shimin; Yan, Yong

2013-09-01

147

Transverse injection of a particle-laden liquid jet in supersonic flow: A three-phase flow  

NASA Technical Reports Server (NTRS)

The results of a two part study of the behavior of particle laden liquid jets injected into air are presented. Water was used as the liquid carrier and either 1-37 or 13-44 microns diam. spherical glass beads with a specific gravity of 2.8-3.0 as the particles. The observations were mainly photographic. The breakup of jets injected into still air was investigated as a function of particle loading, and the results were compared to the pure liquid jet case. The jets were found to be more stable with particles present. The length to breakup was increased, and the formation of satellite droplets was suppressed. The penetration and breakup of transverse jets in a Mach 3.0 air stream was studied. The general breakup mechanism of wave formation was found to be the same as for the all liquid case. Significant separation of the phases was observed, and the penetration of the liquid phase was reduced compared to all liquid cases at the same value of the jet to free stream momentum flux ratio.

Schetz, J. A.; Ogg, J. C.

1980-01-01

148

Investigation on the generation process of impact-driven high-speed liquid jets using a CFD technique  

NASA Astrophysics Data System (ADS)

High-speed liquid jets have been applied to many fields of engineering, science and medicine. It is therefore of benefit to all these areas to investigate their characteristics by modern and inexpensive methods using a computational fluid dynamics (CFD) technique. Previously, high-speed liquid jets have been studied experimentally using a momentum exchange method, called the "impact driven method (IDM)", by which the impact of a high-velocity projectile on the liquid package contained in the nozzle cavity produced the jet. The shock pulse reflections in the cavity caused by the impact then drove a multiple pulsed jet from the nozzle exit. In this study, a two-fluid simulation consisting of liquid and air can be successfully calculated by using a two-phase flow mixture model and a moving mesh for the projectile motion. The CFD results show good agreement to the results of previous experimental studies, both quantitatively and qualitatively. For the first time, the wave propagation within the liquid in the nozzle has been captured and analyzed, thereby demonstrating the dynamic characteristics of multiple pulsed high-speed liquid jets initiated by the IDM. This provides a breakthrough in the simulation of the supersonic injection of a liquid into air by using a well-known and user-friendly CFD software. It is useful fundamental knowledge for future studies of high-speed injection with applications in all its related fields.

Seehanam, W.; Pianthong, K.; Sittiwong, W.; Milton, B. E.; Takayama, K.

2012-09-01

149

Thorough small-angle X-ray scattering analysis of the instability of liquid micro-jets in air.  

PubMed

Liquid jets are of interest, both for their industrial relevance and for scientific applications (more important, in particular for X-rays, after the advent of free-electron lasers that require liquid jets as sample carrier). Instability mechanisms have been described theoretically and by numerical simulation, but confirmed by few experimental techniques. In fact, these are mainly based on cameras, which is limited by the imaging resolution, and on light scattering, which is hindered by absorption, reflection, Mie scattering and multiple scattering due to complex air/liquid interfaces during jet break-up. In this communication it is demonstrated that synchrotron small-angle X-ray scattering (SAXS) can give quantitative information on liquid jet dynamics at the nanoscale, by detecting time-dependent morphology and break-up length. Jets ejected from circular tubes of different diameters (100-450?µm) and speeds (0.7-21?m?s(-1)) have been explored to cover the Rayleigh and first wind-induced regimes. Various solvents (water, ethanol, 2-propanol) and their mixtures have been examined. The determination of the liquid jet behaviour becomes essential, as it provides background data in subsequent studies of chemical and biological reactions using SAXS or X-ray diffraction based on synchrotron radiation and free-electron lasers. PMID:24365936

Marmiroli, Benedetta; Cacho-Nerin, Fernando; Sartori, Barbara; Pérez, Javier; Amenitsch, Heinz

2014-01-01

150

Time-resolved simulations and experiments of liquid jet break-up  

NASA Astrophysics Data System (ADS)

High-speed, high-resolution experimental visualization of the break-up of a liquid jet by a gaseous cross-flow has recently become possible due to advances in video camera technology. These visualizations can now be contrasted to high fidelity CFD simulations which are also just becoming possible due to continuing growth of computational capabilities. Such a contrast is expected to go beyond traditional comparisons of time-averaged quantities and focuses on dynamics. For example, comparisons of the characteristic break-up frequency and of the spatial instantaneous features of the jet may serve as validation of the computational model and to yield insight into the physics of the dynamic interplay between the disturbances induced by the injection device and Kelvin-Helmholtz / Rayleigh-Taylor instabilities at the interface. A state-of-the-art second-order coupled Level Set and Volume Of Fluid method (CLSVOF) that can capture liquid-gas interface dynamics is used for the study. High-speed videos of non-turbulent liquid injection in laminar crossflow are used to validate the time- and grid-converged capability of the code to capture upwind wave structures caused by the centrifugal acceleration of the deflected liquid. The extension to increasing air crossflow is also discussed with focus on the column break-up mechanism.

Arienti, Marco; Soteriou, Marios; Sussman, Mark

2008-11-01

151

Laser fragmentation of organic microparticles into colloidal nanoparticles in a free liquid jet  

NASA Astrophysics Data System (ADS)

We present a novel approach for laser fragmentation of melamine cyanurate microcrystals suspended in liquid into colloidal nanoparticles. Laser fragmentation is done by irradiating a liquid jet of melamine cyanurate suspended in water with intense picosecond pulses. The free liquid jet is generated by a nozzle with small diameter and provides a thin liquid filament ( d fil<1 mm) perpendicular to the focused laser beam. This geometry allows tight focusing resulting in high intensities without the danger of damaging an optical element like windows necessary in conventional flow cells or cuvettes. It reduces losses of excitation light by avoiding scattering or absorption in front of the focus. We stabilized the nanoparticles electrosterically in-situ with neutral and polyelectrolytic polymers preventing agglomeration and precipitation. The threshold for sufficient stabilization of laser-fragmented nanoparticles ( d hydrodyn?200 nm) is reached at a mass fraction of 0.25 wt% dextrin as a neutral polymer and 0.01 wt% polyacrylic acid as a polyelectrolytic polymer. Hydrodynamic size and zeta-potential of the nanoparticles can be controlled by mass fraction of the stabilization agent.

Wagener, Philipp; Barcikowski, Stephan

2010-11-01

152

Production of jet fuels from coal-derived liquids. Volume 15. Thermal stability of coal-derived jet fuels. Final report, September 1988December 1989  

Microsoft Academic Search

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were compared to similar fuel samples produced from petroleum. Large quantities of oxygen compounds were found in the coal derived liquids and were

S. Eser; C. Song; R. M. Copenhaver; J. Perison; H. H. Schobert

1990-01-01

153

Production of jet fuels from coal-derived liquids. Volume 14. Oxygenates content of coal-derived jet fuels. Interim report, 26 November 1986-31 July 1989  

Microsoft Academic Search

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were compared to similar fuel samples produced from petroleum. Large quantities of oxygen compounds were found in the coal-derived liquids and were removed

Knudson

1990-01-01

154

Two-Dimensional Optical Measurement of Waves on Liquid Lithium Jet Simulating IFMIF Target Flow  

SciTech Connect

Waves on a liquid-lithium jet flow, simulating a proposed high-energy beam target design, have been measured using an optical technique based on specular reflection of a single laser beam on the jet surface. The stream-wise and spanwise fluctuations of the local free-surface slope were least-square fitted with a sinusoidal curve to makeup the signals lost due to the constriction in the optical arrangement. The waveform was estimated with an assumption that wave phase speed can be calculated using the dispersion relation for linear capillary-gravity waves. The direction of propagation on the jet surface was also evaluated so that the wave amplitudes, calculated by integral of slope angle signal, agree consistently in stream-wise and spanwise direction. These measurements and analyses show that the waves at the measurement location for a jet velocity of 1.2 m/s can best be represented by oblique waves with an inclination of 1.23 rad, a wavelength of 3.8 mm and a wave amplitude of about 0.05 mm. (authors)

Kazuhiro Itoh; Hiroyuki Koterazawa [University of Hyogo, 1-3-3, Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo (Japan); Taro Itoh; Yutaka Kukita [Nagoya University, Furo-cho, Chikusa-ku, Nagoya-shi, Aichi, 464-8603 (Japan); Hiroo Kondo; Nobuo Yamaoka; Hiroshi Horiike [Osaka University, 1-8 Yamadaoka, Suita, Osaka 565-0871 (Japan); Mizuho Ida; Hideo Nakamura; Hiroo Nakamura [Japan Atomic Energy Agency (Japan); Takeo Muroga [National Institute for Fusion Science, 322-6, Oroshi-cho, Toki, GIFU, 509-5292 (Japan)

2006-07-01

155

Interaction of DC Microhollow Cathode Discharge Plasma Micro Jet with Liquid Media  

NASA Astrophysics Data System (ADS)

There have been different approaches in studying the interaction between plasma and liquid, such as sustained plasmas in contact with liquids and pulsed electric discharge in liquids. Recently, we have discovered that stable plasma can be sustained within a gas cavity maintained inside liquid media. A prototype device with key dimensions in sub-millimeter range were operated successfully in de-ionized water and turbo molecular pump oil with ambient air, pure nitrogen or pure oxygen used as the operating gas. Hydrogen Peroxide production in de-ionized water with ambient air as the working gas is estimated to be about 80 mg/L after 15 minutes plasma jet-water interaction while energy consumption is only about 8-10 W. With the radicals readily generated and directly introduced into the liquid media, it could lead to applications such as in-liquid bio-waste treatment, bio-rich liquid modification, in-situ monitoring/sensing, and filtration of by-products from VOC treatment by plasma.

Zhu, Weidong; Lopez, Jose; Becker, Kurt

2008-10-01

156

Production of jet fuels from coal-derived liquids. Volume 14, Oxygenates content of coal-derived jet fuels: Interim report, November 26, 1986-July 31, 1989.  

National Technical Information Service (NTIS)

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Results were com...

C. L. Knudson

1990-01-01

157

Liquid and gelled sprays for mixing hypergolic propellants using an impinging jet injection system  

NASA Astrophysics Data System (ADS)

The characteristics of sprays produced by liquid rocket injectors are important in understanding rocket engine ignition and performance. The includes, but is not limited to, drop size distribution, spray density, drop velocity, oscillations in the spray, uniformity of mixing between propellants, and the spatial distribution of drops. Hypergolic ignition and the associated ignition delay times are also important features in rocket engines, providing high reliability and simplicity of the ignition event. The ignition delay time is closely related to the level and speed of mixing between a hypergolic fuel and oxidizer, which makes the injection method and conditions crucial in determining the ignition performance. Although mixing and ignition of liquid hypergolic propellants has been studied for many years, the processes for injection, mixing, and ignition of gelled hypergolic propellants are less understood. Gelled propellants are currently under investigation for use in rocket injectors to combine the advantages of solid and liquid propellants, although not without their own difficulties. A review of hypergolic ignition has been conducted for selected propellants, and methods for achieving ignition have been established. This research is focused on ignition using the liquid drop-on-drop method, as well as the doublet impinging jet injector. The events leading up to ignition, known as pre-ignition stage are discussed. An understanding of desirable ignition and combustion performance requires a study of the effects of injection, temperature, and ambient pressure conditions. A review of unlike-doublet impinging jet injection mixing has also been conducted. This includes mixing factors in reactive and non-reactive sprays. Important mixing factors include jet momentum, jet diameter and length, impingement angle, mass distribution, and injector configuration. An impinging jet injection system is presented using an electro-mechanically driven piston for injecting liquid and gelled hypergolic propellants. A calibration of the system is done with water in preparation for hypergolic injection, and characteristics of individual water and gelled JP-8 jets are studied at velocities in the range of 3 ft/s to 61 ft/s. The piston response is also analyzed to characterize the startup and steady state liquid jet velocities using orifices of 0.02" in diameter. Using this injection system, water and gelled JP-8 sprays are formed and compared across injection velocities of 30 ft/s to 121 ft/s. The comparison includes sheet shape and disintegration, total number of drops, drop size distributions, drop eccentricity, most populated drop bin size, and mean drop sizes. A test matrix for investigating the effects of mixing on ignition of MMH and IRFNA through different injection conditions are presented. First, water and IRFNA are injected to create a spray in the combustion chamber in order to verify effectiveness of test procedures and the test hardware. Next, injection of the hypergolic propellants MMH and IRFNA are done in accordance to the test matrix, although ignition was not observed as expected. These injections are followed by simple drop-on-drop tests to investigate propellant quality and ignition delay. Drop tests are performed with propellants IRFNA/MMH, and again with H2O2/Block 0 as possible propellant replacements for the proposed test plan.

James, Mark D.

158

Experimental study of the hydrodynamic and heat transfer of free liquid jet impinging a flat circular heated disk  

Microsoft Academic Search

This study concerns the hydrodynamic and the thermal characteristics of the free liquid jet impinged a heated disk. The thin liquid layer depth is measured along the axial and the radial directions using the laser induced fluorescence and image processing. The experimental results are compared to the laminar and turbulent theories of Watson [E.J. Watson, The radial spread of a

J. B. Baonga; H. Louahlia-Gualous; M. Imbert

2006-01-01

159

Hydrocarbon group type determination in jet fuels by high performance liquid chromatography  

NASA Technical Reports Server (NTRS)

Results are given for the analysis of some jet and diesel fuel samples which were prepared from oil shale and coal syncrudes. Thirty-two samples of varying chemical composition and physical properties were obtained. Hydrocarbon types in these samples were determined by fluorescent indicator adsorption (FIA) analysis, and the results from three laboratories are presented and compared. Recently, rapid high performance liquid chromatography (HPLC) methods have been proposed for hydrocarbon group type analysis, with some suggestion for their use as a replacement of the FIA technique. Two of these methods were used to analyze some of the samples, and these results are also presented and compared. Two samples of petroleum-based Jet A fuel are similarly analyzed.

Antoine, A. C.

1977-01-01

160

Experimental analysis of the performance of an air-powered needle-free liquid jet injector.  

PubMed

An experimental study was performed using a custom-built air-powered needle-free injector to investigate the various injector parameters governing the dynamics of jet injection. A parametric study using five different nozzle sizes at driver pressure ranging from 4 to 8 bar was carried out. The fluid stagnation pressure of the liquid jet was determined using a Honeywell force sensor. Performance plots as a function of various parameters were constructed. It was determined that as the driver pressure increased both the peak and average stagnation pressure increased almost linearly within the operating range considered. Varying the injection nozzle diameter, whilst keeping the driver pressure constant did not have any significant impact on the peak or average stagnation pressure. The chamber length was also varied and no significant influence was found on peak or average stagnation pressure. PMID:24110483

Portaro, Rocco; Ng, Hoi Dick

2013-01-01

161

Liquid helium inertial jet for comparative study of classical and quantum turbulence  

SciTech Connect

We present a new cryogenic wind tunnel facility developed to study the high Reynolds number developed classical or quantum turbulence in liquid {sup 4}He. A stable inertial round jet flow with a Reynolds number of 4 x 10{sup 6} can be sustained in both He I and He II down to a minimum temperature of 1.7 K. The circuit can be pressurized up to 3.5 x 10{sup 5} Pa. The system has been designed to exploit the self-similar properties of the jet far field in order to adapt to the spatial resolution of the existing probes. Multiple and complementary sensors can be simultaneously installed to obtain spatial and time resolved measurements. The technical difficulties and design details are described and the system performance is presented.

Duri, D. [UJF-Grenoble 1, Grenoble-INP, CNRS, LEGI UMR 5519, Grenoble F-38041 (France); SBT, UMR-E 9004 CEA/UJF-Grenoble 1, INAC, Grenoble F-38054 (France); Baudet, C.; Virone, J. [UJF-Grenoble 1, Grenoble-INP, CNRS, LEGI UMR 5519, Grenoble F-38041 (France); Charvin, P.; Rousset, B.; Poncet, J.-M.; Diribarne, P. [SBT, UMR-E 9004 CEA/UJF-Grenoble 1, INAC, Grenoble F-38054 (France)

2011-11-15

162

Experimental Investigation of Jet Impingement Heat Transfer Using Thermochromic Liquid Crystals  

NASA Technical Reports Server (NTRS)

Jet impingement cooling of a hypersonic airfoil leading edge is experimentally investigated using thermochromic liquid crystals (TLCS) to measure surface temperature. The experiment uses computer data acquisition with digital imaging of the TLCs to determine heat transfer coefficients during a transient experiment. The data reduction relies on analysis of a coupled transient conduction - convection heat transfer problem that characterizes the experiment. The recovery temperature of the jet is accounted for by running two experiments with different heating rates, thereby generating a second equation that is used to solve for the recovery temperature. The resulting solution requires a complicated numerical iteration that is handled by a computer. Because the computational data reduction method is complex, special attention is paid to error assessment. The error analysis considers random and systematic errors generated by the instrumentation along with errors generated by the approximate nature of the numerical methods. Results of the error analysis show that the experimentally determined heat transfer coefficients are accurate to within 15%. The error analysis also shows that the recovery temperature data may be in error by more than 50%. The results show that the recovery temperature data is only reliable when the recovery temperature of the jet is greater than 5 C, i.e. the jet velocity is in excess of 100 m/s. Parameters that were investigated include nozzle width, distance from the nozzle exit to the airfoil surface, and jet velocity. Heat transfer data is presented in graphical and tabular forms. An engineering analysis of hypersonic airfoil leading edge cooling is performed using the results from these experiments. Several suggestions for the improvement of the experimental technique are discussed.

Dempsey, Brian Paul

1997-01-01

163

Gas-phase flowrate effect on disintegrating cryogenic liquid-jets  

NASA Technical Reports Server (NTRS)

Two phase liquid and gaseous nitrogen flow in a pneumatic two fluid atomizer was investigated. Characteristic dropsize for cryogenic sprays were measured with a scattered light scanning instrument developed at NASA-Lewis. Tests were conducted primarily in the aerodynamic stripping regime of liquid jet atomization. At a sampling distance of bar-x =1.3 cm, the Sauter mean, D(sub 32), and volume median, D(sub v.5), drop diameters were measured and correlated with nitrogen gas flowrate, W(sub n), to give the following expressions: D sub 32 to the -1=210W(sub n) to the -1.33 and D(sub v.5) to the -1=150 W(sub n to the -1.33, where reciprocal diameters and gas flowrate are in cm (-1) and g/sec, respectively. The exponent 1.33 for nitrogen gas flowrate, W(sub n), is the same as that predicted by atomization theory for liquid-jet breakup in high velocity gasflow. When the spray was sampled at axial distances of bar-x=2.5 and 4.5 cm downstream of the atomizer, the exponent decreased to 1.2 and 0.9, respectively. This was attributed to the loss of small droplets due to their rapid vaporization.

Ingebo, Robert D.

1990-01-01

164

Gas-phase flowrate effect on disintegrating cryogenic liquid-jets  

NASA Technical Reports Server (NTRS)

Two phase liquid and gaseous nitrogen flow in a pneumatic two fluid atomizer was investigated. Characteristic dropsize for cryogenic sprays were measured with a scattered light scanning instrument developed at NASA-Lewis. Tests were conducted primarily in the aerodynamic stripping regime of liquid jet atomization. At a sampling distance of bar-x=1.3 cm, the Sauter mean, D(sub 32), and volume median, D(sub v.5), drop diameters were measured and correlated with nitrogen gas flowrate, W(sub n), to give the following expressions: D sub 32 to the -1=210W(sub n) to the -1.33 and D(sub v.5) to the -1=150 W(sub n to the -1.33, where reciprocal diameters and gas flowrate are in cm (-1) and g/sec, respectively. The exponent 1.33 for nitrogrn gas flowrate, W(sub n), is the same as that predicted by atomization theory for liquid-jet breakup in high velocity gasflow. When the spray was sampled at axial distances of bar-x=2.5 and 4.5 cm downstream of the atomizer, the exponent decreased to 1.2 and 0.9, respectively. This was attributed to the loss of small droplets due to their rapid vaporization.

Ingebo, Robert D.

1989-01-01

165

Organic-vapor-liquid-solid deposition with an impinging gas jet  

NASA Astrophysics Data System (ADS)

A method for rapid, mass-efficient deposition of highly crystalline organic films under near ambient conditions of pressure and temperature is reported based on delivery of an organic precursor via an impinging gas jet to a substrate coated by a thin liquid solvent layer. Films of the organic semiconductor tetracene were deposited by sublimation into a flow of argon carrier gas directed at an indium-tin-oxide/glass substrate coated by a thin layer of bis(2-ethylhexyl)sebecate, and growth was followed in situ with optical microscopy. A fluid dynamics model is applied to account for the gas phase transport and aggregation, and the results compared to experiment. The combination of gas jet delivery with an organic-vapor-liquid-solid growth mechanism leads to larger crystals and lower nucleation densities than on bare surfaces, with markedly different nucleation and growth kinetics. An explanation based on enhanced solution-phase diffusivity and a larger critical nucleus size in the liquid layer is proposed to account for the differences.

Shaw, Daniel W.; Bufkin, Kevin; Baronov, Alexandr A.; Johnson, Brad L.; Patrick, David L.

2012-04-01

166

Temporal instability of coflowing liquid-gas jets under an electric field  

NASA Astrophysics Data System (ADS)

Temporal instability of an electrified liquid jet in the core of a high-speed gas stream is studied to better understand the electro-flow focusing (EFF) technique. Two types of physical models with and without viscosities of fluids are considered. One utilizes uniform basic flow and an axial electric field, while the other one considers both the axial and radial electric fields and employs appropriate velocity profiles based on the pipe flow for inner liquid and the error function for outer gas stream. Both models demonstrate that the axisymmetric instability and the helical instability are two most unstable modes in the EFF problem. The significance of free charge initially imposed on the interface is highlighted and the effects of surface tension and liquid viscosity on the jet instability are also studied. It is shown that the increase of free charge density can definitely promote both the axisymmetric and helical instabilities and the transition between them arises for sufficiently large free charge densities when the axial electric field intensity increases. Finally, the EFF experiments are carried out to compare with theoretical predictions in the temporal instability analysis and a good agreement between them is achieved.

Li, Guangbin; Luo, Xisheng; Si, Ting; Xu, Ronald X.

2014-05-01

167

Cooling of a multichip electronic module by means of confined two-dimensional jets of dielectric liquid  

Microsoft Academic Search

Experiments were performed to investigate single-phase heat transfer from a smooth 12.7 x 12.7-sq-mm simulated chip to a two-dimensional jet of dielectric FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confinement channel height, and impingement velocity have been examined. Channel height had a negligible

D. C. Wadsworth; I. Mudawar

1990-01-01

168

The production of lithium oxide microspheres from the disintegration of a liquid jet  

SciTech Connect

Microspheres of lithium hydroxide (LiOH) were produced from in-flight solidification of droplets formed by the disintegration of an acoustically driven, mechanically vibrated cylindrical liquid jet of molten LiOH. The molten material at 470 to 480{degrees}C was fed through a 25-gauge (0.0267-cm bore diameter) nozzle, interiorly electroplated with silver, under {approximately}27.6-kPa (4-psig) pressure, and at a mechanical vibration frequency of 10 Hz. The resulting jet issued into a 5.5-cm-diam vertical glass drop tube entraining a 94.5 cm{sup 3}/s (12 ft{sup 3}/h) argon gas stream at 75{degrees}C. The 100-cm-long drop tube was sufficient to allow the droplets of molten LiOH resulting from jet disintegration to solidify in-flight without catastrophic thermal shock, being then collected a solid microspheres. These LiOH microspheres were then vacuum processed to lithium oxide (Li{sub 2}O). Preliminary experiments resulted in microspheres with diameters varying from 120 to 185 {mu}m, but with evidence of impurity contamination occurring during the initial stages of the process.

Al-Ubaidi, M.R. (Univ. of Cincinnati, OMI College of Applied Sciences, Cincinnati, OH (US)); Anno, J.N. (Univ. of Cincinnati, College of Engineering, Cincinnati, OH (US))

1989-12-01

169

Liquid phase products and solid deposit formation from thermally stressed model jet fuels  

NASA Technical Reports Server (NTRS)

The relationship between solid deposit formation and liquid degradation product concentration was studied for the high temperature (400 C) stressing of three hydrocarbon model fuels. A Jet Fuel Thermal Oxidation Tester was used to simulate actual engine fuel system conditions. The effects of fuel type, dissolved oxygen concentration, and hot surface contact time (reaction time) were studied. Effects of reaction time and removal of dissolved oxygen on deposit formation were found to be different for n-dodecane and for 2-ethylnaphthalene. When ten percent tetralin is added to n-dodecane to give a simpler model of an actual jet fuel, the tetralin inhibits both the deposit formation and the degradation of n-dodecane. For 2-ethylnaphthalene primary product analyses indicate a possible self-inhibition at long reaction times of the secondary reactions which form the deposit precursors. The mechanism of the primary breakdown of these fuels is suggested and the primary products which participate in these precursor-forming reactions are identified. Some implications of the results to the thermal degradation of real jet fuels are given.

Kim, W. S.; Bittker, D. A.

1984-01-01

170

Movement of liquid beryllium during melt events in JET with ITER-like wall  

NASA Astrophysics Data System (ADS)

The ITER-like wall recently installed in JET comprises solid beryllium limiters and a combination of bulk tungsten and tungsten-coated carbon fibre composite divertor tiles without active cooling. During a beryllium power handling qualification experiment performed in limiter configuration with 5 MW neutral beam injection input power, accidental beryllium melt events, melt layer motion and splashing were observed locally on a few beryllium limiters in the plasma contact areas. The Lorentz force is responsible for the observed melt layer movement. To move liquid beryllium against the gravity force, the current flowing from the plasma perpendicularly to the limiter surface must be higher than 6 kA m?2. The thermo-emission current at the melting point of beryllium is much lower. The upward motion of the liquid beryllium against gravity can be due to a combination of the Lorentz force from the secondary electron emission and plasma pressure force.

Sergienko, G.; Arnoux, G.; Devaux, S.; Matthews, G. F.; Nunes, I.; Riccardo, V.; Sirinelli, A.; Huber, A.; Brezinsek, S.; Coenen, J. W.; Mertens, Ph; Philipps, V.; Samm, U.; EFDA contributors, JET

2014-04-01

171

Exhaust emissions from a premixing, prevaporizing flame tube using liquid jet A fuel  

NASA Technical Reports Server (NTRS)

Emissions of nitrogen oxides, carbon monoxide, and unburned hydrocarbons were measured in a burner where liquid Jet A fuel was sprayed into the heated air stream and vaporized upstream of a perforated plate flameholder. The burner was tested at inlet air temperatures at 640, 800, and 833 K, an inlet pressure of 5.6 X 100,000 N/m squared, a reference velocity of 25 m/sec, and equivalence ratios from lean blowout to 0.7. Nitrogen oxide levels of below 1.0 g NO2/kg fuel were obtained at combustion efficiencies greater than 99 percent. The measured emission levels for the liquid fuel agreed well with previously reported premixed gaseous propane data and agreed with well stirred reactor predictions. Autoignition of the premixed fuel air mixture was a problem at inlet temperatures above 650 K with 104 msec premixing time.

Marek, C. J.; Papathakos, L. C.

1976-01-01

172

Numerical study of impact of evaporation on liquid jet in cross-flow  

NASA Astrophysics Data System (ADS)

Atomization of a liquid fuel jet by a high speed cross-flowing gas plays a critical role in many propulsion devices. High fidelity simulation offers the potential of a better understanding and enhancement of this atomization process. In this work, a computationally efficient hybrid Eulerian-Lagrangian approach is coupled with a droplet evaporation model and is used to probe the impact of evaporation on the spray development. The Coupled Level Set and Volume of Fluid (CLSVOF) method is used to directly calculate the breakup and coalescence of the liquid-gas interface. Adaptive Mesh Refinement (AMR) is adopted to achieve high resolution at the interface. Small fuel droplets in dilute regions are removed from the Eulerian description, transformed into Lagrangian particles and tracked by a discrete phase transport model. The coupling of the spray evaporation to the gas phase is examined with respect to jet blockage, spray penetration, and overall far-field spray dispersion. The calculation is validated with flow rate, spray size distribution and velocity data acquired in a spray rig at high-Weber, high-Reynolds number injection conditions. The effect of evaporation on spray distribution is also discussed.

Soteriou, Marios; Li, Xiaoyi; Arienti, Marco

2010-11-01

173

Heat Transfer Characteristics of Turbulent Impinging Jet in Impingement Angle and Curved Surface Configuration using Transient Liquid Crystal Method  

NASA Astrophysics Data System (ADS)

The transient method of measuring heat transfer coefficients that uses liquid crystals, since its beginnings in the early 1980s, has become one of the best ways of determining surface distributions of heat transfer coefficient. In this paper, experimental results are presented of local surface heat transfer coefficients in a turbulent jet, impinging onto a curved surface which has the convex and concave surfaces. The preheated wall transient method is applied with liquid crystals. Different Reynolds numbers, distances between impingement jet and collision surface, and inclined angles are considered. This paper reports the correlation at the stagnation point heat transfer coefficients of Reynolds number, distances, and impingement inclined angles with Nusselt numbers.

Lee, Changhee; Lim, Kyungbin

174

Simulating the dynamics of three-dimensional plunging flows  

Microsoft Academic Search

This present research addressed the fundamental hydromechanics of plunging flows, i.e., the processes governing mixing of a fluid in motion with a water body at rest, when the fluid bodies are of differing density. It has been demonstrated that there is a need to treat these processes in a three-dimensional context, when the real system being studied is of irregular

Xiaochun Wang

2000-01-01

175

Production of jet fuels from coal-derived liquids. Volume 3. Jet fuels potential of liquid by-products from the Great Plains Gasification Project. Interim report, September 1986December 1987  

Microsoft Academic Search

Three liquid by-products from the Great Plains Gasification Project, tar oil crude phenols, and naptha, were evaluated as potential sources of military jet fuels. Tar oil, produced at about 3200 barrels per day (BPD), is a highly aromatic lignite-pyrolysis liquid with a typical density of 1.01 and boiling range of about 220-975 F (104-524). Crude phenols, extracted from process water

E. B. Smith; F. D. Guffey; L. G. Nickerson

1988-01-01

176

Production of jet fuels from coal-derived liquids. Volume 6. Preliminary analysis of upgrading alternatives for the Great Plains liquid by-production streams. Interim report, March 1987February 1988  

Microsoft Academic Search

Amoco and Lummus Crest have developed seven cases for upgrading by-product liquids from the Great Plains Coal Gasification plant to jet fuels, and in several of the cases, saleable chemicals in addition to jet fuels. The analysis shows that the various grades of jet fuel can be produced from the Great Plains tar oil, but not economically. However the phenolic

B. A. Fleming; J. D. Fox; M. W. Furlong; J. G. Masin; L. P. Sault

1988-01-01

177

Production of jet fuels from coal-derived liquids. Volume 13. Evaluation of storage and thermal stability of jet fuels derived from coal liquids. Interim report, August 1988December 1989  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory of WPAFB, OH, began an investigation of the potential of the production of jet fuel from the liquid by-products streams produced by the gasification of lignite at the Great Plains Gasification Plant (GPGP) in Beulah, North Dakota. Funding was provided to the Department of Energy, Pittsburgh Energy Technology Center,

G. P. Sturm; R. D. Grigsby; J. W. Goetzinger; J. B. Green; R. P. Anderson

1990-01-01

178

OPTIMIZED DETERMINATION OF TRACE JET FUEL VOLATILE ORGANIC COMPOUNDS IN HUMAN BLOOD USING IN-FIELD LIQUID-LIQUID EXTRACTION WITH SUBSEQUENT LABORATORY GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS AND ON-COLUMN LARGE VOLUME INJECTION  

EPA Science Inventory

A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing te...

179

Cooling of a multichip electronic module by means of confined two-dimensional jets of dielectric liquid  

SciTech Connect

Experiments were performed to investigate single-phase heat transfer froma smooth 12.7 {times} 12.7 mm{sup 2} simulated chip to a two-dimensional jet of dielectric Fluorinert FC-72 liquid issuing from a thin rectangular slot into a channel confined between the chip surface and nozzle plate. The effects of jet width, confined channel height, and impingement velocity have been examined. Channel height had a negligible effect ont eh theat transfer performance of the jet for the conditions of the present study. A correlation for the convective heat transfer coefficient is presented as a function of jet, width, heat length, flow velocity, and fluid properties. A self-contained multichip cooling module consisting of a 3 {times} 3 array of heat sources confirmed the uniformity and predictability of cooling for each of the nine chips, and proved the cooling module is well suited for packaging large arrays of high-power density chips.

Wadsworth, D.C.; Mudawar, I. (Purdue Univ., West Layfayette, IN (USA))

1990-11-01

180

Experimental and numerical investigation of the plunge stage in friction stir welding  

Microsoft Academic Search

A better understanding of the plunge phase is critical with the growing role of friction stir spot welding and also in understanding tool wear in case of friction stir welding (FSW) of high strength alloys. This paper investigates the plunge stage using experimental and numerical modeling. Plunge experiments were performed on aluminum 2024 alloy with simultaneous measurement of temperature and

S. Mandal; J. Rice; A. A. Elmustafa

2008-01-01

181

Stability and debris in high-brightness liquid-metal-jet-anode microfocus x-ray sources  

SciTech Connect

We investigate the x-ray spot stability and the debris emission in liquid-metal-jet anode electron-impact x-ray sources operating in the 10-100 W microfocus regime. The x-ray spot size is 15-23 {mu}m in diameter and the electron-beam power density is up to {approx}210 kW/mm{sup 2}, an order of magnitude higher than for conventional microfocus sources. In the power range of the investigation the source is stable in terms of spot size and position. The debris emission rate increases exponentially with the applied electron-beam power but may be reduced by combining larger and faster target jets with smaller e-beam foci and by mitigation schemes. It is concluded that the investigated factors will not limit the performance and function of liquid-metal-jet-anode electron-impact microfocus sources when operating in this high-brightness regime.

Otendal, M.; Tuohimaa, T.; Hertz, H. M. [Biomedical and X-ray Physics, Department of Applied Physics, Royal Institute of Technology/Albanova, SE-106 91 Stockholm (Sweden)

2007-01-15

182

Scattered-light scanner measurements of cryogenic liquid-jet breakup  

NASA Technical Reports Server (NTRS)

The effect of highly turbulent Mach 1 gas flow and high thermal gradients on drop size measurements was investigated with a scattered light scanner. The instrument, developed at NASA-Lewis, was used to measure characteristic drop diameters or cyrogenic liquid sprays. By correcting for gas turbulence and thermal gradient affects, it was possible to obtain good reproducible data with the scattered light scanner. Tests were conducted primarily in the aerodynamic-stripping regime of liquid atomization and it was found that the loss of small droplets due to vaporization and dispersion had a marketed effect on drop size measurements. The nitrogen gas flow rate exponent of 1.33 is the same as that predicted by atomization theory for liquid jet breakup in high velocity gas flow. However, when the sprays were sampled farther downstream of the atomizer, at axial distances of 2.5 and 4.5 cm, the exponent for W sub n decreased 1.2 and 0.9, respectively. This was attributed to the loss of small droplets due to vaporization when values of downstream axial distances exceeded 1.3 cm.

Ingebo, Robert D.; Buchele, Donald R.

1990-01-01

183

Liquid-nitrogen-jet laser-plasma source for compact soft x-ray microscopy  

SciTech Connect

We describe a liquid-nitrogen-jet laser-plasma source with sufficient brightness, uniformity, stability, and reliability to be suitable for compact water-window soft x-ray transmission microscopy. A cooled capillary nozzle arrangement allows long-term operation and avoids previously reported jet instabilities. The source is quantitatively characterized by calibrated slit-grating spectroscopy and zone-plate imaging. The absolute photon number in the major spectral lines ({lambda}=2.48 nm and {lambda}=2.88 nm) is 1.0x10{sup 12} photons/(pulsexsrxline). The source diameter is {approx}20 {mu}m (full width at half maximum) and the spatial stability is better than {+-}2 {mu}m. Within an area with uniformity of 20%, the average source brightness is 4x10{sup 8} photons/(pulsexsrx{mu}m{sup 2}xline), which allows operation of a compact soft x-ray transmission microscope with exposure times of a few minutes.

Jansson, P.A.C.; Vogt, U.; Hertz, H.M. [Biomedical and X-Ray Physics, Royal Institute of Technology/Albanova, SE-106 91 Stockholm (Sweden)

2005-04-01

184

Liquid jet impingement normal to a disk in zero gravity. Ph.D. Thesis Toledo Univ.  

NASA Technical Reports Server (NTRS)

The free surface shapes of circular liquid jets impinging normal to sharp-edged disks in zero gravity are determined. Zero gravity drop tower experiments yielded three distinct flow patterns that were classified in terms of the relative effects of surface tension and inertial forces. An order of magnitude analysis was conducted that indicated regions where viscous forces were not significant in the computation of free surface shapes. The free surface analysis was simplified by transforming the governing potential flow equations and boundary conditions into the inverse plane, where the stream function and velocity potential became the coordinates. The resulting nonlinear equations were solved by standard finite difference methods, and comparisons were made with the experimental data for the inertia dominated regime.

Labus, T. L.

1977-01-01

185

Deposition of micron liquid droplets on wall in impinging turbulent air jet  

NASA Astrophysics Data System (ADS)

The fluid mechanics of the deposition of micron liquid (olive oil) droplets on a glass wall in an impinging turbulent air jet is studied experimentally. The spatial patterns of droplets deposited on a wall are measured by using luminescent oil visualization technique, and the statistical data of deposited droplets are obtained through microscopic imagery. Two distinct rings of droplets deposited on a wall are found, and the mechanisms of the formation of the inner and outer rings are investigated based on global diagnostics of velocity and skin friction fields. In particular, the intriguing effects of turbulence, including large-scale coherent vortices and small-scale random turbulence, on micron droplet deposition on a wall and coalescence in the air are explored.

Liu, Tianshu; Nink, Jacob; Merati, Parviz; Tian, Tian; Li, Yong; Shieh, Tom

2010-06-01

186

Phase-contrast x-ray imaging with a liquid-metal-jet-anode microfocus source  

SciTech Connect

Phase-contrast methods increase contrast, detail, and selectivity in x-ray imaging. Present compact x-ray sources do not provide the necessary spatial coherence with sufficient power to allow the laboratory-scale high-resolution phase-contrast imaging with adequate exposure times. In this letter, the authors demonstrate phase-contrast imaging with few-micron detail employing a compact {approx}6.5 {mu}m spot liquid-metal-jet-anode high-brightness microfocus source. The 40 W source is operated at more than ten times higher electron-beam power density than present microfocus sources and is shown to provide sufficient spatial coherence as well as scalability to high power, thereby enabling the application of phase-contrast x-ray imaging with short exposure times in clinics and laboratories.

Tuohimaa, T.; Otendal, M.; Hertz, H. M. [Biomedical and X-Ray Physics, Department of Applied Physics, KTH Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden)

2007-08-13

187

EROSIVE WEAR OF DUCTILE METALS BY A PARTICLE-LADEN HIGH-VELOCITY LIQUID-JET  

SciTech Connect

A liquid-solid particle jet impingement flow apparatus is described and experimental measurements are reported for the accelerated erosion of copper, aluminum and mild steel sheet metal by coal suspensions in kerosene and alumina and silicon carbide suspensions in water. Slurry velocities of up to 130 ft/sec (40 m/sec) and impingement angles ranging from 15 degrees to 90 degrees were investigated. The maximum particle concentration used was 40% by weight. For high velocity the results of this study show two erosion maxima arising at impingement angles of 90 degrees and 40 degrees respectively~ whereas in corresponding gas-solid particle investigations maximum erosion occurs at approximately 20 degrees. In the study both particle concentration and composition were varied. A polynomial regression technique was used to calculate empirical and semi-theoretical correlation constants.

Li, Simon Ka-Keung; Humphrey, Joseph A.C.; Levy, Alan

1980-12-01

188

Atomization and Dispersion of a Liquid Jet Injected Into a Crossflow of Air  

NASA Technical Reports Server (NTRS)

In recent years, environmental regulations have become more stringent, requiring lower emissions of mainly nitrogen oxides (NOx), as well as carbon monoxide (CO) and unburned hydrocarbons (UHC). These regulations have forced the gas turbine industry to examine non-conventional combustion strategies, such as the lean burn approach. The reasoning behind operating under lean conditions is to maintain the temperature of combustion near and below temperatures required for the formation of thermal nitric oxide (NO). To be successful, however, the lean processes require careful preparation of the fuel/air mixture to preclude formation of either locally rich reaction zones, which may give rise to NO formation, or locally lean reaction zones, which may give rise to inefficient fuel processing. As a result fuel preparation is crucial to the development and success of new aeroengine combustor technologies. A key element of the fuel preparation process is the fuel nozzle. As nozzle technologies have developed, airblast atomization has been adopted for both industrial and aircraft gas turbine applications. However, the majority of the work to date has focused on prefilming nozzles, which despite their complexity and high cost have become an industry standard for conventional combustion strategies. It is likely that the new strategies required to meet future emissions goals will utilize novel fuel injector approaches, such as radial injection. This thesis proposes and demonstrates an experiment to examine, on a mechanistic level (i.e., the physics of the action), the processes associated with the atomization, evaporation, and dispersion of a liquid jet introduced, from a radial, plain-jet airblast injector, into a crossflow of air. This understanding requires the knowledge not only of what factors influence atomization, but also the underlying mechanism associated with liquid breakup and dispersion. The experimental data acquired identify conditions and geometries for improved performance of radial airblast injectors.

Seay, J. E.; Samuelson, G. S.

1996-01-01

189

Void fraction measurements beneath plunging and spilling breaking waves  

Microsoft Academic Search

The temporal and spatial variations of the void fraction fields beneath deepwater breaking waves were investigated in the laboratory. There were a total of 13 measurement positions along the plunging wave; the peak void fractions measured varied from 0.024 to 0.96 and the time-averaged void fractions varied from 0.012 to 0.37. For the spilling wave, there were four measurement positions,

G. Rojas; M. R. Loewen

2010-01-01

190

A Water Model Study of Impinging Gas Jets on Liquid Surfaces  

NASA Astrophysics Data System (ADS)

Water modeling experiments were designed to observe the deformation of a liquid surface by impinging the gas jet. Video images were taken and processed in a systematic way. The important surface cavity parameters, such as depth, width, and their frequency of oscillation, were obtained. The relation between surface depression depth and the supplied gas momentum were consistent with previous findings and were extended to higher flow rates. The surface instability and the onset of splashing were observed and interpreted with the Blowing number. The wave behaviors were described qualitatively with a combination of photographic evidence and power spectral density analysis to extract the characteristic wave numbers for each gas flow rate. The analysis of the time series of the surface variables showed a connection to the attenuation of turbulence gas pressure fluctuation and the surface deformation by the gas impingement. Bath velocities were measured with a particle image velocimetry (PIV) technique. To quantify the transfer of kinetic energy from the gas to the liquid, an energy transfer index was defined and calculated with the PIV data. The index was insensitive to gas flow rate but increased with cavity width. The momentum transfer across the interface was also analyzed, and a similar cavity width dependence was found. A correlation between the cavity shape and momentum transfer was proposed.

Hwang, Ho Yong; Irons, Gordon A.

2012-04-01

191

The Properties of Flowing Sheets Formed by Impingement of Liquid Jets on Curved Surfaces  

NASA Technical Reports Server (NTRS)

An applied research program was conducted to determine the properties of flat sheets of propellants formed by directing jets of liquid tangentially against concave, cylindrical deflector surfaces. The dimensions and spatial orientation of the resultant sheets were found to depend only on the orifice diameter and deflector geometry for three propellant simulants of widely-varying physical properties, over the range of injection velocities encountered in liquid rocket engines. Correlating equations, suitable for use in injector design, are presented for free-sheet width and spreading angle. Distribution of mass and velocity across the free-flowing sheets is also reported. Conditions were discovered under which true sheets do not form, or at best malformed or pulsating sheets result. An envelope of geometrical constraints for deflector design is tentatively defined in order to avoid these undesirable operating regions. The results of the present cold-flow tests are compared with firing test data for impinging-sheet injectors and combustion performance is related to single sheet behavior.

Riebling, Robert W.; Powell, Walter B.

1966-01-01

192

The generation of singular liquid jets in the axisymmetric bubble pinch-off at high Reynolds numbers  

NASA Astrophysics Data System (ADS)

In this presentation we review the symmetric and asymmetric type of bubble pinch-off local geometries described in PRL, 95, 194501, and provide with the different scalings for the minimum radius, R0, as the singularity is approached. Moreover, in the case of gas inertia is not relevant in the description of the latest stages of bubble breakup (symmetric pinch-off), local bubble shape is given by F(z,t)/R0(t)=1-[1/(6,og(R0))],z/R0)^2. However, we also discuss that the asymptotic solutions for the symmetric case are only reached for times so close to pinch off that they might be difficult to find and, therefore, bubble pinch-off strongly depends on initial conditions. Regarding the asymmetric type of breakup, we provide new experimental evidence that support that, close to pinch-off, gas and liquid inertia are balanced. We will show that the velocity of the singular liquid jets formed within air and helium bubbles generated from a needle immersed in a coaxial co-flow strongly depends on gas density. More precisely, the ratio of the liquid jet velocity formed using air (ua) to the liquid jet velocity formed using helium (uh) is given, for the same operating conditions, by ua/uh˜,?air/?helium)^1/n, with 2

Gordillo, J. M.; Sevilla, A.; Rodriguez-Rodriguez, J.; Martinez-Bazan, C.; Perez-Saborid, M.

2006-11-01

193

A review of research related to the development of liquid jet fluidics  

Microsoft Academic Search

The approaches of the control logic for electronic and fluid systems are considered along with the nature of jets and jet deflection, questions of air fluidics, hydraulic fluidics, the teapot effect, free jet fluidics, and fluidic reliability. Applications of fluidic techniques are also discussed, giving attention to a fluid oscillator operating with air as a temperature sensor. Another application is

H. R. Martin; S. B. Friedman

1974-01-01

194

Quantitative Determination of Compound Classes in Jet Turbine Fuels by High Performance Liquid Chromatography/Differential Refractive Index Detection. Part 2.  

National Technical Information Service (NTIS)

Recent investigations demonstrated the usefulness of high performance liquid chromatography/differential refractive index detection (HPLC/DRI) as a method for quantitating compound classes present in jet fuels. The method is fast, precise and accurate whe...

C. W. Sink D. R. Hardy R. N. Hazlett

1984-01-01

195

Investigation of a Nonlinear Outcoupling Feature Observed in Optically-Pumped Cylindrical Liquid Jets Supporting Stimulated Raman Scattering  

Microsoft Academic Search

Two processes associated with the generation of stimulated Raman scattering (SRS) in optically-pumped cylindrical liquid jets are investigated. First, the mechanism of frequency selectivity occurring in a micro-cavity with a continuum of resonant frequencies is discussed. It appears that the restrictions placed on the continuous parameter beta, which describes the z dependence of the normal modes of the micro-cylinder, results

Thomas Eric Ruekgauer

1995-01-01

196

Liquid jet breakup characterization with application to melt-water mixing  

SciTech Connect

Severe accidents in light-water reactors could lead to the flow of molten core material from the initial core region of the reactor vessel to the lower plenum. Steam explosions have been predicted to occur as a result of the contact of the melt with water available in the plenum. It is presently judged by many workers, that the magnitude of the energy released during such an in-vessel explosion would be insufficient to lead to failure of the containment building (SERG, 1985). A major contributing factor in this judgment is that the mass of melt which would participate in the interaction would be limited by the quantity of melt delivered to the lower plenum to the time of the explosion and by the limited breakup of the molten pour stream as it flows through the plenum prior to the explosion. Limited pour stream breakup would lead to limited melt-water mixing and, in addition, to the existence of ''large-scale'' melt masses which may lead to very inefficient thermal-to-mechanical energy conversion. The objective of this paper is to assess the available literature relevant to liquid jet breakup and to assess its implications with respect to the behavior of molten corium pour streams as they would flow from the core region through the lower plenum. Uncertainties in application of the available literature are discussed. 7 refs., 2 figs.

Ginsberg, T.

1986-01-01

197

Formation of a Liquid Jet by Interaction between a Laser-induced Bubble and a Shock Wave  

PubMed Central

Summary There are some problems such as a narrow therapeutic time window and severe side effects of fibrinolytics in the therapy of cerebral embolisms. Therefore, it is necessary to develop a new method to remove a cerebral thrombus more rapidly with fewer fibrinolytics. A Q-switch pulsed holmium (Ho): YAG laser with 86 mJ/pulse, pulse duration of 200ns and wavelength of 2.1 mm was used. The laser beam was transmitted through a 0.6 mm diameter quartz optical fiber. Experiments were conducted in a stainless steel container equipped with observation windows .The test chamber was filled with distilled water at 283K. At first, the formation of laser-induced bubbles in a 4 mm diameter glass tube was observed. The bubble gradually expanded and reached a maximum size at about lms after irradiation. A shock wave induced by ignition of silver azide pellet was interacted with it at 500µs before Ho:YAG laser irradiation, which resulted in forming a liquid jet. This liquid jet penetrated into an artificial thrombus made of gelatin, and its maximum penetration depth was 4.2 mm, which was nearly twice deeper than the laser irradiation only (2.2 mm). Combination of this liquid jet and fibrinolytics will realize more rapid recanalization with fewer drugs.

Hirano, T.; Komatsu, M.; Ezura, M.; Uenohara, H.; Takahashi, A.; Takayama, K.; Yoshimoto, T.

2001-01-01

198

Plunging congenital epidermoid cyst of the oral cavity.  

PubMed

Epidermoid cysts are rare lesions in the oral cavity. They usually present early in life and are confined to one anatomical area. Simple excision is all that is needed. However, they may present late in life and be large in size, making their excision a real challenge. We present a case of congenital epidermoid cyst of the sublingual space that presented late, at the age of 17 years, after it plunged into the submental area. The presentation of the patient and the surgical approach are discussed. PMID:12709808

Bitar, MohamedJ A M F A; Kumar, Shimareet

2003-04-01

199

Simulating the dynamics of three-dimensional plunging flows  

NASA Astrophysics Data System (ADS)

This present research addressed the fundamental hydromechanics of plunging flows, i.e., the processes governing mixing of a fluid in motion with a water body at rest, when the fluid bodies are of differing density. It has been demonstrated that there is a need to treat these processes in a three-dimensional context, when the real system being studied is of irregular geometry as in nature and is inherently unsteady, as when flows are regulated upstream of the mixing zone. A three-dimensional hydrodynamic numerical model was used to explore ranges of the governing variables in space and time, utilizing first the cases of hypothetical rectangular channels and then the case of Whiskeytown Reservoir to illustrate quantitatively the effects of operation and environmental conditions on system behavior. The effects of unsteadiness of inflow boundary conditions on plunging flow dynamics were investigated through a series of simulations conducted for various cases of boundary inflow in a hypothetical straight rectangular channel. The results indicated that changes in both rates and temporal patterns of inflow shaped the dynamics of plunging flows. The effects of secondary currents were examined by conducting simulations in a hypothetical rectangular channel with a simple bend. The simulations demonstrated that the bend induced strong secondary currents that, in turn, enhanced transverse and vertical transport of momentum and mass in the locale of the bend, resulting in changes in flow directions, perturbations in gradients of vertical velocities and temperatures, and plunge depth. It was found from the present study that the model, RMA10, is a useful tool for assessing the relative merits of alternative physical situations and operational scenarios in Whiskeytown Reservoir. Simulations conducted for three alternative inflow scenarios indicated that combinations of complex geometry and unsteady inflow, especially with abrupt changes in inflow rate, intensified mixing between warm upper and lower cold water layers in the upper reach of the reservoir. Comparisons between field observations and model simulations confirmed the capability of the model to correctly represent the real world behavior as observed in the reservoir. The calibrated model is available for use by project operators to assist in achieving desired temperature control for protection of salmon fisheries below the project.

Wang, Xiaochun

200

Image analysis of jet structure on electrospinning from free liquid surface  

NASA Astrophysics Data System (ADS)

The work analyses intra-jet distances during electrospinning from a free surface of water based poly(vinyl alcohol) solution confined by two thin metallic plates employed as a spinning electrode. A unique computer vision system and digital image processing were designed in order to track position of every polymer jet. Here, we show that jet position data are in good compliance with theoretically predicted intra-jet distances by linear stability analysis. Jet density is a critical parameter of electrospinning technology, since it determines the process efficiency and homogeneity of produced nanofibrous layer. Achievements made in this research could be used as essential approach to study jetting from two-dimensional spinning electrodes, or as fundamentals for further development of control system related to Nanospider™ technology.

Kula, Jiri; Linka, Ales; Tunak, Maros; Lukas, David

2014-06-01

201

Maximum heat flux in relation to quenching of a high temperature surface with liquid jet impingement  

Microsoft Academic Search

Experimental investigation has been conducted for quenching of hot cylindrical blocks made of copper, brass and steel with initial block temperature 250–400°C by a subcooled water jet of diameter of 2mm. The subcooling was from 5 to 80K and the jet velocity was from 3 to 15m\\/s. After impingement, the jet stagnates for a certain period of time in a

Aloke Kumar Mozumder; Masanori Monde; Peter Lloyd Woodfield

2006-01-01

202

Simulation of a Plunging Airfoil with a Flexible Tail  

NASA Astrophysics Data System (ADS)

The fluid motion of an airfoil with a flexible tail is simulated using an unsteady panel method with diffusive wake modeling. The fluid simulation is coupled with a CSD solver to simulate the deflection of the flexible tail due to both inertial and aerodynamic forces. The modal equations were used to calculate the structural deformation under an aerodynamic load. Computations with varying stiffness coefficient and reduced frequencies were performed to produce a performance map of a plunging airfoil with a flexible tail. The results showed a range of reduced frequencies and tail stiffness that increased the thrust produced by the plunging motion by as much as 45% when compared with the same airfoil that has a rigid tail. The propulsive efficiency with a flexible tail increased slightly as well. The upper limit of the thrust enhancement is bounded by the first natural frequency of the flexible tail. A stiffer tail is shown to be most beneficial, but the minimum reduced frequency where thrust is improved increases with increasing stiffness. Spectral analysis of the unsteady forces and wake velocities showed that the increase in thrust can be directly attributed to the effect the flexible tail has on the wake vorticies.

Lai, Alan; Liu, Feng

2010-11-01

203

On the current emitted by Taylor cone-jets of electrolytes in vacuo: Implications for liquid metal ion sources  

NASA Astrophysics Data System (ADS)

Approximate scaling laws for the charge and size of the drops ejected from the apex of Taylor cones run in the cone-jet mode (electrospray) are now available for highly conducting electrolytes (10-4 S/mliquid flow rate curves I(Q) characteristic of a given liquid are investigated both in vacuum and in atmospheric pressure air. Although the sprays of drops differ profoundly in both cases, the two corresponding I(Q) curves are nearly identical for relatively involatile liquids such as tributyl phosphate. A discussion on the possible relation between the behavior of Taylor cones of electrolytes of organic liquids and liquid metal ion sources (K~106 S/m) is attempted, yielding insights on the role of space charge. However, the electrical conductivity variable which dominates the behavior of liquid cones of electrolytes appears to be irrelevant in liquid metals.

Gamero-Castaño, M.; Aguirre-de-Carcer, I.; de Juan, L.; Fernández de La Mora, J.

1998-03-01

204

Modeling Single-Phase and Boiling Liquid Jet Impingement Cooling in Power Electronics.  

National Technical Information Service (NTIS)

Jet impingement has been an attractive cooling option in a number of industries over the past few decades. Over the past 15 years, jet impingement has been explored as a cooling option in microelectronics. Recently, interest has been expressed by the auto...

S. V. Narumanchi V. Hassani D. Bharathan

2005-01-01

205

Fluid dynamics and convective heat transfer in impinging jets through implementation of a high resolution liquid crystal technique  

NASA Astrophysics Data System (ADS)

A combined convective heat transfer and fluid dynamics investigation in a turbulent round jet impinging on a flat surface is presented. The experimental study uses a high resolution liquid crystal technique for the determination of the convective heat transfer coefficients on the impingement plate. The heat transfer experiments are performed using a transient heat transfer method. The mean flow and the character of turbulent flow in the free jet is presented through five hole probe and hot wire measurements, respectively. The flow field character of the region near the impingement plate plays an important role in the amount of convective heat transfer. Detailed surveys obtained from five hole probe and hot wire measurements are provided. An extensive validation of the liquid crystal based heat transfer method against a conventional technique is also presented. After a complete documentation of the mean and turbulent flow field, the convective heat transfer coefficient distributions on the impingement plate are presented. The near wall of the impingement plate and the free jet region is treated separately. The current heat transfer distributions are compared to other studies available from the literature. The present paper contains complete sets of information on the three dimensional mean flow, turbulent velocity fluctuations, and convective heat transfer to the plate. The experiments also prove that the present nonintrusive heat transfer method is highly effective in obtaining high resolution heat transfer maps with a heat transfer coefficient uncertainty of 5.7 percent.

Kim, K.; Wiedner, B.; Camci, C.

206

Fluid dynamics and convective heat transfer in impinging jets through implementation of a high resolution liquid crystal technique  

NASA Technical Reports Server (NTRS)

A combined convective heat transfer and fluid dynamics investigation in a turbulent round jet impinging on a flat surface is presented. The experimental study uses a high resolution liquid crystal technique for the determination of the convective heat transfer coefficients on the impingement plate. The heat transfer experiments are performed using a transient heat transfer method. The mean flow and the character of turbulent flow in the free jet is presented through five hole probe and hot wire measurements, respectively. The flow field character of the region near the impingement plate plays an important role in the amount of convective heat transfer. Detailed surveys obtained from five hole probe and hot wire measurements are provided. An extensive validation of the liquid crystal based heat transfer method against a conventional technique is also presented. After a complete documentation of the mean and turbulent flow field, the convective heat transfer coefficient distributions on the impingement plate are presented. The near wall of the impingement plate and the free jet region is treated separately. The current heat transfer distributions are compared to other studies available from the literature. The present paper contains complete sets of information on the three dimensional mean flow, turbulent velocity fluctuations, and convective heat transfer to the plate. The experiments also prove that the present nonintrusive heat transfer method is highly effective in obtaining high resolution heat transfer maps with a heat transfer coefficient uncertainty of 5.7 percent.

Kim, K.; Wiedner, B.; Camci, C.

1993-01-01

207

Electronic absorption spectroscopy of PAHs in supersonic jets and ultracold liquid helium droplets  

NASA Astrophysics Data System (ADS)

Neutral and cationic polycyclic aromatic hydrocarbons (PAHs) are discussed as possible carriers of the diffuse interstellar bands (DIBs), still unassigned astrophysical absorption features observed in the spectra of reddened stars (Salama et al. 1999). Despite the importance of this class of molecules for astrophysics and nanophysics (PAHs can be regarded as nanoscale fragments of a sheet of graphite), the spectroscopic characterization of PAHs under well-defined conditions (low temperature and collision-free environment) has remained a challenge. Recently we have set up a cavity ring-down spectrometer combined with a pulsed supersonic jet expansion to study neutral and cationic PAHs under astrophysical conditions. PAHs studied so far include the neutral molecules anthracene (Staicu et al. 2004) and pyrene (Rouillé et al. 2004) as well as the cationic species naphthalene+ and anthracene+ (Sukhorukov et al. 2004). Employing another molecular beam apparatus, the same molecules (except of the cationic species) were also studied in liquid helium droplets (Krasnokutski et al. 2005, Rouillé et al. 2004). This novel technique combines several advantages of conventional matrix spectroscopy with those of gas phase spectroscopy. Notable advantages are the possibility to study molecules with low vapor pressure and to use a mass spectrometer facilitating spectral assignments. The most recent studies were devoted to phenanthrene and the more complicated (2,3)-benzofluorene. These molecules were investigated in the gas phase by cavity ring-down spectroscopy and in liquid helium droplets using depletion spectroscopy. For benzofluorene the present studies constitute the first reported measurements both in the gas phase and in helium droplets. The origin of the S1 ? S0 gas phase transition could be located at 29 894.3 cm-1, and a series of vibronic bands was recorded below 31 500 cm-1. In contrast to previously studied PAHs, the shift induced by the helium droplets was very small (blue shift between 4.5 and 4.9 cm-1 for all vibronic bands). With this new gas phase data, a value of 247 cm-1 is derived for the red shift experienced by the molecule in an argon matrix (Banisaukas et al. 2004). For the molecules studied up to now, no coincidence between experimental and interstellar band positions was found.

Huisken, Friedrich; Staicu, Angela; Krasnokutski, Serge; Henning, Thomas

208

GRB 110328A/SWIFT J164449.3+573451: THE TIDAL OBLITERATION OF A DEEPLY PLUNGING STAR?  

SciTech Connect

We examine the tidal disruption event (TDE) scenario to explain Sw 1644+57, a powerful and persistent X-ray source which suddenly became active as GRB 110328A. The precise localization at the center of a z = 0.35 galaxy argues for activity of the central engine as the underlying cause. We look at the suggestion by Bloom et al. of the possibility of a TDE. We argue that Sw 1644+57 cannot be explained by the traditional TDE model in which the periastron distance is close to the tidal disruption radius-three independent lines of argument indicate the orbit must be deeply plunging or else the powerful jet we are observing could not be produced. These arguments stem from (1) comparing the early X-ray light curve to the expected theoretical fallback rate, (2) looking at the time of transition to disk-dominated decay, and (3) considering the TDE rate. Due to the extreme excess in the tidal force above that which would be required minimally to disrupt the star in a deeply plunging orbit at periastron, we suggest this scenario might be referred to more descriptively as a tidal obliteration event (TOE) rather than a TDE.

Cannizzo, J. K. [CRESST and Astroparticle Physics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Troja, E. [Astroparticle Physics Laboratory NASA/GSFC, Greenbelt, MD 20771 (United States); Lodato, G., E-mail: John.K.Cannizzo@nasa.gov [Dipartimento di Fisica, Universita degli Studi di Milano, Milano 20133 (Italy)

2011-11-20

209

Visco Jet Joule-Thomson Device Characterization Tests in Liquid Methane  

NASA Technical Reports Server (NTRS)

Joule-Thomson (J-T) devices have been identified as critical components for Thermodynamic Vent Systems (TVS) planned for future space exploration missions. Lee Visco Jets (The Lee Company) (Ref. 4) are one type of J-T device that may be used for LCH4 propellant systems. Visco Jets have been previously tested and characterized in LN2 and LH2 (Refs. 6 and 7), but have not been characterized in LOX or LCH4. Previous Visco Jet tests with LH2 resulted in clogging of the Visco Jet orifice under certain conditions. It has been postulated that this clogging was due to the presence of neon impurities in the LH2 that solidified in the orifices. Visco Jets therefore require testing in LCH4 to verify that they will not clog under normal operating conditions. This report describes a series of tests that were performed at the NASA Glenn Research Center to determine if Visco Jets would clog under normal operating conditions with LCH4 propellant. Test results from this program indicate that no decrease in flow rate was observed for the Visco Jets tested, and that current equation used for predicting flow rate appears to under-predict actual flow at high Lohm ratings.

Jurns, John M.

2009-01-01

210

Flow structure and performance of a flexible plunging airfoil  

NASA Astrophysics Data System (ADS)

An investigation was performed with the intent of characterizing the effect of flexibility on a plunging airfoil, over a parameter space applicable to birds and flapping MAVs. The kinematics of the motion was determined using of a high speed camera, and the deformations and strains involved in the motion were examined. The vortex dynamics associated with the plunging motion were mapped out using particle image velocimetry (PIV), and categorized according to the behavior of the leading edge vortex (LEV). The development and shedding process of the LEVs was also studied, along with their flow trajectories. Results of the flexible airfoils were compared to similar cases performed with a rigid airfoil, so as to determine the effects caused by flexibility. Aerodynamic loads of the airfoils were also measured using a force sensor, and the recorded thrust, lift and power coefficients were analyzed for dependencies, as was the overall propulsive efficiency. Thrust and power coefficients were found to scale with the Strouhal number defined by the trialing edge amplitude, causing the data of the flexible airfoils to collapse down to a single curve. The lift coefficient was likewise found to scale with trailing edge Strouhal number; however, its data tended to collapse down to a linear relationship. On the other hand, the wake classification and the propulsive efficiency were more successfully scaled by the reduced frequency of the motion. The circulation of the LEV was determined in each case and the resulting data was scaled using a parameter developed for this specific study, which provided significant collapse of the data throughout the entire parameter space tested.

Akkala, James Marcus

211

Comparison of two turbulence models in simulating an axisymmetric jet evolving into a tank  

NASA Astrophysics Data System (ADS)

Experiments and computational fluid dynamics (CFD) simulations have been carried out to investigate a turbulent water jet plunging into a tank filled with the same liquid. To avoid air bubble entrainment which may be caused by surface instabilities, the free falling length of the jet is set to zero. For both impinging region and recirculation zone, measurements are made using Particle Image Velocimetry (PIV). Instantaneous- and time-averaged velocity fields are obtained. Numerical data is obtained on the basis of both ? - epsilon and SSG (Speziale, Sarkar and Gatski) of Reynolds Stresses Turbulent Model (RSM) in three dimensional frame and compared to experimental results via the axial velocity and turbulent kinetic energy. For axial distances lower than 5cm from the jet impact point, the axial velocity matches well the measurements, using both models. A progressive difference is found near the jet for higher axial distances from the jet impact point. Nevertheless, the turbulence kinetic energy agrees very well with the measurements when applying the SSG-RSM model for the lower part of the tank, whereas it is underestimated in the upper region. Inversely, the ? - epsilon model shows better results in the upper part of the water tank and underestimates results for the lower part of the water tank. From the overall results, it can be concluded that, for single phase flow, the ? - epsilon model describes well the average axial velocity, whereas the turbulence kinetic energy is better represented by the SSG-RSM model.

Zidouni Kendil, F.; Danciu, D.-V.; Lucas, D.; Bousbia Salah, A.; Mataoui, A.

2011-12-01

212

From jet to drops via jets  

Microsoft Academic Search

We investigate the dynamics of the impact of two liquid jets at an angle, paying a particular attention to the atomization process. The drops mean diameter and velocity produced by the break up of the resultant jet for different impacting jets diameters and velocities is documented. We show that the impact conserves the momentum flux and we characterize this continuous

N. Bremond; C. Clanet; E. Villermaux

2002-01-01

213

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Kinetics of particles of the liquid-drop phase of erosion jets in crossed laser beams  

NASA Astrophysics Data System (ADS)

The kinetics of the liquid-drop phase of a lead erosion jet in crossed laser beams was studied. Neodymium laser radiation was used in the primary interaction and for additional evaporation. The diameter, and the number and volume concentration of particles in an erosion jet, were measured. It was possible to alter greatly the parameters of the condensed phase in crossed beams at low energies of the evaporating laser radiation. The results obtained should be useful in the generation of two-phase jets with controlled parameters and of a sterile drop-free erosion plasma.

Goncharov, V. K.; Puzyrev, M. V.

1997-04-01

214

Deposit formation in liquid fuels. I - Effect of coal-derived Lewis bases on storage stability of Jet A turbine fuel  

NASA Technical Reports Server (NTRS)

The development of reasonably precise techniques for the measurement of storage stability of jet aviation fuel is described. Lewis bases, extracted by ligand-exchange from a coal-derived liquid, are shown to adversely affect storage stability (as determined by an accelerated storage test) when added to Jet A turbine fuel. JFTOT results suggesting slight decreases in thermal stability of fuel 'spiked' (i.e., contaminated with a measured quantity of reagent) with extract are reported. Addition to Jet A turbine fuel of individual heterocyclic nitrogen compounds is shown to produce comparable decreases in storage stability.

Dahlin, K. E.; Daniel, S. R.; Worstell, J. H.

1981-01-01

215

Generation of capillary instabilities by external disturbances in a liquid jet. Ph.D. Thesis - State Univ. of N.Y.  

NASA Technical Reports Server (NTRS)

The receptivity problem in a circular liquid jet is considered. A time harmonic axial pressure gradient is imposed on the steady, parallel flow of a jet of liquid emerging from a circular duct. Using a technique developed in plasma physics a casual solution to the forced problem is obtained over certain ranges of Weber number for a number of mean velocity profiles. This solution contains a term which grows exponentially in the downstream direction and can be identified with a capillary instability wave. Hence, it is found that the externally imposed disturbances can indeed trigger instability waves in a liquid jet. The amplitude of the instability wave generated relative to the amplitude of the forcing is computed numerically for a number of cases.

Leib, S. J.

1985-01-01

216

High-brightness water-window electron-impact liquid-jet microfocus source  

SciTech Connect

We demonstrate stable high-brightness operation of an electron-impact water-jet-anode soft x-ray source. A 30 kV, 7.8 W electron beam is focused onto a 20 mum diameter jet resulting in water-window oxygen line emission at 525 eV/2.36 nm with a brightness of 3.0x10{sup 9} ph/(sxmum{sup 2}xsrxline). Monte Carlo-based modeling shows good quantitative agreement with the experiments. The source has potential to increase the x-ray power and brightness by another 1-2 orders of magnitude and fluid-dynamical jet instabilities is determined to be the most important limiting factor. The source properties make it an attractive alternative for table-top x-ray microscopy.

Skoglund, P.; Lundstroem, U.; Vogt, U.; Hertz, H. M. [Department of Applied Physics, Biomedical and X-Ray Physics, Royal Institute of Technology, SE-10691 Stockholm (Sweden)

2010-02-22

217

Femtosecond laser-plasma interaction with prepulse-generated liquid metal micro-jets  

SciTech Connect

Ultra-short laser pulse interaction with a micro-structured surface of a melted metal is a promising source of hard X-ray radiation. Micro-structuring is achieved by a weak prepulse which produces narrow high density micro-jets. Interaction of the main laser pulse with such jets is shown to be a 100 times more efficient X-ray source than ordinary metal targets. This paper presents the results of optical and x-ray studies of laser-plasma interaction physics under such conditions supported by numerical simulations of fast electron generation.

Uryupina, D. S.; Ivanov, K. A.; Brantov, A. V.; Savel'ev, A. B.; Bychenkov, V. Yu.; Volkov, R. V.; Tikhonchuk, V. T. [Faculty of Physics and International Laser Center of M.V. Lomonosov Moscow State University, 119991, Moscow, Leninskie Gory (Russian Federation); P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow (Russian Federation); P. N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow (Russian Federation); CELIA, University of Bordeaux - CNRS - CEA, 33405 Talence (France)

2012-07-11

218

The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Third quarterly technical report, July 1, 1993--September 30, 1993  

SciTech Connect

Laminar and turbulent columns of liquids issuing from capillary tubes were studied in order to determine the effects of turbulence on the stability of liquid jets and to establish the influence of liquid turbulence on droplet size distributions after breakup. Two capillary tubes were chosen with diameters D{sub 1}=3.0mm and D{sub 2}=1.2mm; jet Reynolds numbers were 1000--30000, and 400--7200. For water injection into stagnant air, stability curve is bounded by a laminar portion, where a jet radius and {delta}{sub o} initial disturbance amplitude, and a fully developed turbulent portion characterized by high initial disturbance amplitude (ln(a/{delta}{sub o,T}) {approximately} 4.85). In the transition region, ln(a/{delta}{sub o}) is not single valued; it decreases with increasing Reynolds number. In absence of aerodynamic effects, turbulent jets are as stable as laminar jets. For this breakup mode turbulence propagates initial disturbances with amplitudes orders of magnitude larger than laminar jets ({delta}{sub o,T}=28{times}10{sup 6} {delta}{sub o,L}). Growth rates of initial disturbances are same for both laminar and turbulent columns with theoretical Weber values. Droplet size distribution is bi-modal; the number ratio of large (> D/2), to small (< D/2) droplets is 3 and independent of Reynolds number. For laminar flow optimum wavelength ({lambda}{sub opt}) corresponding to fastest growing disturbance is equal to 4.45D, exactly the theoretical Weber value. For turbulent flow conditions, the turbulent column segments. Typically, segments with lengths of one to several wavelengths, detach from the liquid jet. The long ligaments contract under the action of surface tension, resulting in droplet sizes larger than predicted by Rayleigh and Weber. For turbulent flow conditions, {lambda}{sub opt} = 9.2D, about 2 times the optimum Weber wavelength.

Mansour, A.; Chigier, N.

1993-12-01

219

Simulation of the influence of different liquids for ink jets under the aspect of color printing  

Microsoft Academic Search

In this paper an improved three-dimensional model of a bubble-jet printhead is presented. It is based on the governing physical phenomena of the bubble growth and its subsequent collapse. It contains the complete heat conduction through the different layers and a realistic geometry of the firing chamber and the nozzle. Furthermore, the temperature dependence of various thermodynamic parameters such as

Joachim Patzer; Eberhard P. Hofer; Gerhard Beurer

1994-01-01

220

Investigation of a Nonlinear Outcoupling Feature Observed in Optically-Pumped Cylindrical Liquid Jets Supporting Stimulated Raman Scattering.  

NASA Astrophysics Data System (ADS)

Two processes associated with the generation of stimulated Raman scattering (SRS) in optically-pumped cylindrical liquid jets are investigated. First, the mechanism of frequency selectivity occurring in a micro-cavity with a continuum of resonant frequencies is discussed. It appears that the restrictions placed on the continuous parameter beta, which describes the z dependence of the normal modes of the micro-cylinder, results in a discrete emission spectrum for the stimulated processes (e.g., dye-lasing and SRS) occurring in the dielectric micro-cylinder. A simple model, based on geometric optics, describing the gain and leakage loss for a semi-infinite dielectric slab containing a (semi-infinite) gain region is used to illuminate the role which the parameter beta plays in the generation of stimulated processes in the dielectric micro-cylinder. The results of the model, along with various experimental results, indicate that beta = 0 is the preferred condition for the stimulated processes. Second, it appears as if SRS occurring in the optically-pumped cylindrical liquid jets is responsible for the generation of a newly-observed outcoupling (scattering) feature. This geometrically well-defined feature takes the form of a thin ring, lying in the rm e_{r}-rm e_ {phi} plane, with a spatial extent along the cylinder axis direction of <=q 5 mum. The ring feature is found to be a threshold process, as it is observed to outcouple resident SRS light only above a well-defined optical pump intensity. Finally, it is observed that the ring feature can take on a periodic (in phi) character for particular liquids (ethanol and water) and over a range of optical pump intensities. An explanation for the mechanism responsible for the generation of the ring feature based on plasma generation resulting from self-focusing of the SRS fields is offered.

Ruekgauer, Thomas Eric

1995-01-01

221

Production of jet fuels from coal-derived liquids. Volume 7. GPGP jet-fuels production program. Evaluation of technical uncertainties for producing jet fuels from liquid by-products of the Great Plains gasification plant. Interim report, 2 October 1987-30 September 1988  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio, began an investigation of the potential of jet-fuel production from the liquid by-product streams produced by the gasification of lignite at the Great Plains Gasification Plant (GPGP) in Beulah, North Dakota. Funding was provided by the Department of Energy (DOE) Pittsburgh Energy Technology

M. D. Fraser; R. J. Rossi; E. I. Wan

1989-01-01

222

Innovative Technology Summary Report: Blade Plunging Cutter. Deactivation and Decommissioning Focus Area.  

National Technical Information Service (NTIS)

The Los Alamos Integrating Contractor Team demonstrated a Blade Plunging Cutter as an innovative metal cutting technology under the Large-Scale Demonstration and Deployment Project (LSDDP). The particular model tested was the BPC-4, developed by the Mega-...

2001-01-01

223

Studies on the mixing of liquid jets and pre-atomized sprays in confined swirling air flows for lean direct injection combustion  

NASA Astrophysics Data System (ADS)

A lean direct injection (LDI) combustion concept was introduced recently to obtain both low NOsbx emissions and high performance for advanced aircraft gas turbine engines. It was reported that pollutant emissions, especially NOsbx, in a lean combustion mode depend significantly on the degree of mixing (mixedness) of supplied air and liquid fuel droplets. From a viewpoint of environmental protection, therefore, uniform mixing of fuel and air in a very short period of time, i.e., well-stirred mixing, is crucially important in the LDI combustion mode. In the present study, as the first stage toward understanding the combustion phenomena in a lean direct injection (LDI) mode, the hydrodynamic behavior of liquid jets and pre-atomized sprays in confined swirling air flows is investigated. Laser-based flow visualization and image analysis techniques are applied to analyze the instantaneous motion of the mixing process of the jets and pre-atomized sprays. Statistical analysis system (SAS) software is utilized to analyze the experimental data, and correlate experimental parameters. Statistical parameters, such as centrality, degree of spread, and total area ratio of particles, are defined in this study, and used to quantify the mixedness (degree of mixing) of liquid particles in confined geometry. Two empirical equations are obtained to predict jet intact lengths and spray angles, respectively, in confined swirling air flows. It is found that initial jet characteristics, such as intact length and spray angle, determine the mixing of the liquid particles resulting from the jet. It is verified that image analysis is feasible in quantitative determination of the mixedness of liquid particles. Even though substantial improvements in liquid fuel injector systems are required before they can be considered adequate for LDI combustion at high pressure and high temperature, the results and ideas obtained from the present study will help engineers find better mixing methods for LDI combustors.

Huh, Jun-Young

224

Production of jet fuels from coal-derived liquids. Vol 16. Analysis of phenolic species in coal-derived aviation fuels. Interim report, September 1988July 1989  

Microsoft Academic Search

Samples of jet fuel (JP-4, JP-8, JP-8X) produced from the liquid by-products of the gasification of lignite coal from the Great Plains Gasification Plant were analyzed to determine the quantity and type of organo-oxygen compounds present. Large quantities of oxygen compounds were found in the coal derived liquids and were removed in the refining process. Trace quantities of organo-oxygenate compounds

F. D. Guffey; D. E. Hunter

1990-01-01

225

Three-dimensional Large Eddy Simulation of air entrainment under plunging breaking waves  

Microsoft Academic Search

The scope of this work is to present and discuss the results obtained from simulating three-dimensional plunging breaking waves by solving the Navier-Stokes equations, in air and water, coupled with a dynamic subgrid scale turbulence model (Large Eddy Simulation, LES). An original numerical tool is used for the complete description of the plunging breaking processes including overturning, splash-up and the

Pierre Lubin; Stéphane Vincent; Stéphane Abadie; Jean-Paul Caltagirone

2006-01-01

226

An Experimental Investigation of Liquid Jet Impingement and Single-Phase Spray Cooling Using Polyalphaolefin  

Microsoft Academic Search

Experiments on triangular and rectangular array jet impingement and single-phase spray cooling have been performed to determine the effect of both cooling techniques on heat transfer coefficient (h) and the coolant mass flux required for a given cooling load. Experiments were performed with circular orifices and nozzles for different H\\/D values from 1.5 to 26 and Reynolds number range of

A. K. Sleiti; J. S. Kapat

2006-01-01

227

Liquid mixing enhanced by pulse width modulation in a Y-shaped jet configuration  

NASA Astrophysics Data System (ADS)

In this paper, mixing between two fluid streams, which are injected into a planar mixing channel via a Y-shaped confluence section at the same volume flow rate, is studied experimentally. The injection of the two fluid streams is controlled by two separate solenoid valves, which are operated with a phase difference of 180°, using pulse width modulation. The experiments are conducted using water at a mean Reynolds number between 83 and 250, a range of pulsation frequencies and two duty cycles (25 and 50%). Both particle-image velocimetry and planar laser-induced fluorescence technique are used to visualize the flow patterns and to quantify the mixing degree in the mixing channel. This experiment shows that the pulsation of each jet produces vortical structures, which promotes mixing via vortex entrainment and vortex breakup, and at the same time the mixing is also greatly enhanced by sequential segmentation produced by a 180° out-of-phase pulsation of the two jets. This mixing enhancement method is effective at a Reynolds number greater than 125 with a mixing degree of 0.9 being achieved. For the Reynolds numbers studied in the present experiments, an optimal frequency exists, which corresponds to a Strouhal number in the range of 0.5-2. Furthermore, at a given mean Reynolds number a lower duty cycle is found to produce a better mixing due to the resultant higher instantaneous Reynolds number in the jet flow. It is also found that pulsation of only one jet can produce a similar mixing effect.

Xia, Qingfeng; Zhong, Shan

2013-04-01

228

Numerical heat transfer during partially-confined, confined, and free liquid jet impingement with rotation and chemical mechanical planarization process modeling  

Microsoft Academic Search

This work presents the use of numerical modeling for the analysis of transient and steady state liquid jet impingement for cooling application of electronics, and energy dissipation during a CMP process under the influence of a series of parameters that controls the transport phenomena mechanism. Seven thorough studies were done to explore how the flow structure and conjugated heat transfer

Jorge C. Lallave Cortes

2009-01-01

229

Production of jet fuels from coal-derived liquids. volume 8. heteroatom removal by catalytic processing. Interim report, 1 January30 August 1988  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio, began an investigation of the potential of the production of jet fuel from the liquid by-products streams produced by the gasification of lignite at the Great Plains Gasification Plant in Beulah, North Dakota. Funding was provided to the Department of Energy (DOE), Pittsburgh

J. R. Rindt; M. D. Hetland; C. L. Knudson; W. G. Willson

1989-01-01

230

Interactive graphics system for locating plunge electrodes in cardiac MRI images  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms of ventricular fibrillation and defibrillation requires analysis of epicardial and endocardial potentials throughout the heart. Plunge electrodes permit recording of cardiac potentials at epicardial and endocardial sites, and allow determination of electrical gradients. They also enable us to determine the arrhythmia recurrence sites following failed defibrillation; these sites may be epicardial or endocardial. Therefore, it is necessary to relate the position of the plunge electrodes to the cardiac geometry. We have developed an interactive, computer graphics based system that allows us to locate plunge electrodes on digitized MRI slices of a heart. The system, which can work with any type of image, allows us to identify the epicardial and endocardial points of each plunge electrode on the different MRI slices. Up to 128 different plunge electrodes may be identified to the system. Normalized 3-D coordinates for each epicardial and endocardial electrode point are computed and stored in data files on the computer. Geometry information obtained from this system permits a more thorough understanding of the electrical signals recorded by the plunge electrodes. This information can be used in the study of cardiac excitation and arrhythmias and could help in the development of a more effective lead system for ventricular defibrillation.

Laxer, Cary; Johnson, G. A.; Kavanagh, Katherine M.; Simpson, Edward V.; Ideker, Raymond E.; Smith, William M.

1991-05-01

231

From jet to drops via jets  

NASA Astrophysics Data System (ADS)

We investigate the dynamics of the impact of two liquid jets at an angle, paying a particular attention to the atomization process. The drops mean diameter and velocity produced by the break up of the resultant jet for different impacting jets diameters and velocities is documented. We show that the impact conserves the momentum flux and we characterize this continuous inelastic shock of coalescing fluid by the associated energy loss. We further suggest that this mechanism might be relevant to liquid atomization as it represents an elementary process of liquid sheets atomization. This is, for instance, the case for a plane liquid sheet and also for the radially expanding sheet resulting from the impact of a jet perpendicular to a solid rod. In this second configuration, the sheet is circular and exhibits cusps, or indentations at its periphery. Most of the drops are formed at the focal point of the cusps, a situation very similar to the jets impact configuration.

Bremond, N.; Clanet, C.; Villermaux, E.

2002-11-01

232

Production of jet fuels from coal-derived liquids. Volume 4. GPGP jet-fuels production program-feed analyses compilation and review. Interim report, October 1987January 1988  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio, began an investigation of the potential of jet-fuel production from the liquid by-product streams produced by the gasification of lignite at the Great Plains Gasification Plant (GPGP) in Beulah, North Dakota. Funding was provided to the Department of Energy (DOE) Pittsburgh Energy Technology

Rossi

1988-01-01

233

Production of jet fuels from coal-derived liquids. Volume 10. Jet fuels production by-products, utility, and sulfur-emissions control integration study. Interim report, 1 May 1988-1 April 1989  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio, began an investigation of the potential of jet-fuel production from the liquid by-product streams produced by the gasification of lignite at the Great Plains Gasification Plant (GPGP) in Beulah, North Dakota. Funding has been provided by the Department of Energy (DOE) Pittsburgh Energy

Rossi

1989-01-01

234

Production of jet fuels from coal-derived liquids. Volume 1. Market assessment for liquid by-products from the Great Plains Gasification Plant. Interim report, 20 January30 April 1987  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio commenced an investigation of the potential of production of jet fuel from the liquid by-product streams produced by the gasification of lignite at the Great Plains Gasification Plant in Buelah, North Dakota. Funding was provided to the Department of Energy (DOE) Pittsburgh Energy

Sinor

1987-01-01

235

Production of jet fuels from coal-derived liquids. Volume 2. Characterization of liquid by-products from the Great Plains Gasification Plant. Interim report, 26 November 1986-1 February 1988  

Microsoft Academic Search

The Great Plains Gasification Plant (GPGP) represents the first commercial Syn-Fuels Plant in the United States. The GPGP produces three by-product hydrocarbon liquid streams (rectisol naphtha, crude phenol and tar oil) which are utilized as plant fuel. The purpose of this work was to characterize these streams in order to more fully understand what would be necessary to produce jet

Knudson

1988-01-01

236

Quantitative analysis of the dripping and jetting regimes in co-flowing capillary jets  

Microsoft Academic Search

We study a liquid jet that breaks up into drops in an external co-flowing liquid inside a confining microfluidic geometry. The jet breakup can occur right after the nozzle in a phenomenon named dripping or through the generation of a liquid jet that breaks up a long distance from the nozzle, which is called jetting. Traditionally, these two regimes have

María Luisa Cordero; François Gallaire; Charles N. Baroud

2011-01-01

237

Liquid and gelled sprays for mixing hypergolic propellants using an impinging jet injection system  

Microsoft Academic Search

The characteristics of sprays produced by liquid rocket injectors are important in understanding rocket engine ignition and performance. The includes, but is not limited to, drop size distribution, spray density, drop velocity, oscillations in the spray, uniformity of mixing between propellants, and the spatial distribution of drops. Hypergolic ignition and the associated ignition delay times are also important features in

Mark D. James

2010-01-01

238

Supersonic gasdispersional jets and jet noise  

NASA Technical Reports Server (NTRS)

This paper examines the potential for controlling jet noise radiation using methods developed for modifying jet infra-red thermal radiation. The control of jet noise may be possible by properly adding different solid and liquid particles into the jet flow and by using special nozzle shapes to change the jet exhaust flow structure. The numerical methods used to achieve these objectives are outlined in this paper. A combined Lagrangian-Eulerian approach is used to numerically simulate a Jet flow with particle addition. The unsteady behavior of jet impingement is examined. The techniques for grid and boundary condition definition are discussed as related to the accuracy of the calculations. Preliminary comparisons to experimental data are presented.

Gilinsky, M. M.; Seiner, J. M.; Jansen, B. J.; Bhat, T. R. S.

1993-01-01

239

Application of underwater shock wave and laser-induced liquid jet to neurosurgery  

Microsoft Academic Search

Paper deals with applications of underwater shock waves to medicine. A historical development of underwater shock wave generation\\u000a by using pulsed Ho:YAG laser beam irradiation in water is briefly described and an overview is given regarding potential applications\\u000a of shock waves to neuro-surgery. The laser beam irradiation in a liquid-filled catheter produces water vapor bubble and shock\\u000a waves intermittently produces

T. Tominaga; A. Nakagawa; T. Hirano; J. Sato; K. Kato; S. H. R. Hosseini; K. Takayama

2006-01-01

240

Mathematical Modeling And Design Optimization Of Plunge Shaving Cutter For Gears With Tooth Modifications  

NASA Astrophysics Data System (ADS)

Gears are the most important components in transmission systems. Modifications of gear teeth can accommodate errors and deformations encountered in the manufacture, assembly, and operation of gear pairs. For plunge shaving gears with tooth modifications, the design criteria of cutter clearance manufactured by protuberance hob cutter is investigated. With this novel design, the cutter has better strength and stiffness to keep the shaved gear profile stable. With the analytical descriptions of crowned gear and hence plunge shaving cutter have been constructed so that the grinding wheel can be optimized to minimized the topographic error. Efficiency is greatly improved by avoiding the traditional trial and error method.

Chang, Shinn-Liang; Liu, Jia-Hung

2009-10-01

241

Investigation of jet breakup and droplet size distribution of liquid CO2 and water systems—implications for CO2 hydrate formation for ocean carbon sequestration  

Microsoft Academic Search

An experimental investigation has been conducted into the effect of fluid velocity and orifice size on the breakup patterns of liquid CO2 in water, as well as those for water in CO2. Under high-pressure and low-temperature conditions, the jet breakup patterns follow distinct Rayleigh, transitional, and spray modes. Droplet size distribution was determined in the different modes, with the spray

DAVID RIESTENBERG; ELIZABETH CHIU; MONSURU GBORIGI; LIYUAN LIANG; OLIVIA R. WEST; COSTAS TSOURIS

242

The plunging ranula: diagnostic difficulties and a less invasive approach to treatment.  

PubMed

Plunging ranulas arise when a simple ranula extends beyond the floor of the mouth into the neck. Diagnosis is difficult even with modern imaging techniques as they mimic other neck lesions, and traditional treatment involves enucleation of the cyst from the neck. Despite this invasive surgery they tend to recur. We describe a less invasive approach to treatment and review the diagnostic pitfalls. From 2002 to 2011, eight patients presented with a plunging ranula. They were split into two groups: those for whom an incorrect diagnosis was made and those where a less invasive treatment approach was employed. Three patients were misdiagnosed with cervical lymphangioma and had inappropriately invasive surgery. Five patients with established plunging ranulas were treated using an intraoral approach alone, eliminating the need for a cervical incision. Misdiagnosis of a plunging ranula leads to extensive and unnecessary surgery. We propose an algorithm to simplify investigation that employs a low threshold for fine-needle aspiration cytology. The cases presented indicate that these lesions can be managed by a less invasive procedure than currently practised. PMID:23726274

O'Connor, R; McGurk, M

2013-11-01

243

High-speed and high-accuracy plunge cutting for vertical walls  

Microsoft Academic Search

In metal cutting, a vertical wall is generally cut by end milling. The wall machined by an end mill, however, has low accuracy owing to the bending of the end mill by cutting forces, especially in the case of a deep wall. Plunge cutting carried out using a shoulder-type milling cutter is widely used for cutting vertical walls because of

Shunsuke Wakaoka; Yasuo Yamane; Katsuhiko Sekiya; Norihiko Narutaki

2002-01-01

244

Development of liquid-lithium film jet-flow for the target of (7)Li(p,n)(7)Be reactions for BNCT.  

PubMed

A feasibility study on liquid lithium target in the form of a flowing film was performed to evaluate its potential use as a neutron generation target of (7)Li(p,n)(7)Be reaction in BNCT. The target is a windowless-type flowing film on a concave wall. Its configuration was adapted for a proton beam which is 30mm in diameter and with energy and current of up to 3MeV and 20mA, respectively. The flowing film of liquid lithium was 0.6mm in thickness, 50mm in width and 50mm in length. The shapes of the nozzle and concave back wall, which create a stable flowing film jet, were decided based on water experiments. A lithium hydrodynamic experiment was performed to observe the stability of liquid lithium flow behavior. The flowing film of liquid lithium was found to be feasible at temperatures below the liquid lithium boiling saturation of 342°C at the surface pressure of 1×10(-3)Pa. Using a proto-type liquid lithium-circulating loop for BNCT, the stability of the film flow was confirmed for velocities up to 30m/s at 220°C and 250°C in vacuum at a pressure lower than 10(-3) Pa. It is expected that for practical use, a flowing liquid lithium target of a windowless type can solve the problem of radiation damage and target cooling. PMID:24412425

Kobayashi, Tooru; Miura, Kuniaki; Hayashizaki, Noriyosu; Aritomi, Masanori

2014-06-01

245

Development of gullies on the landscape: A model of headcut retreat resulting from plunge pool erosion  

NASA Astrophysics Data System (ADS)

Head advance due to plunge pool erosion is a common process in gullies incising resistant soils. A model of headcut retreat resulting from plunge pool erosion is developed and implemented in the channel-hillslope integrated landscape development (CHILD) model, an existing three-dimensional landscape evolution modeling framework. The model estimates horizontal headcut retreat as a function of discharge, height of the headcut, upstream slope, and relevant land surface and soil properties for soil erosion. We analyze the sensitivity of headcut retreat to flow discharge, upstream slope and surface roughness, and headcut height. CHILD simulations indicate that headcut retreat is most significant in zones with either gentle slopes or large headcut heights. Model parameters have contrasting effects on the retreat rates depending on the size and depth of the pool beneath the headcut and upstream flow hydraulics, making the process difficult to predict as a function of topographic thresholds and simple geomorphic transport laws.

Flores-Cervantes, Javier H.; Istanbulluoglu, Erkan; Bras, Rafael L.

2006-03-01

246

Fault-related folding during extension: Plunging basement-cored folds in the Basin and Range  

NASA Astrophysics Data System (ADS)

Folds are able to form in highly extended areas where stratified cover rocks respond to basement fault offsets. The response of cover rocks to basement faulting can be studied especially well in plunging structures that expose large structural relief. The southern Basin and Range province contains plunging folds kilometres in amplitude at the corners of domino-like tilt blocks of basement rocks, where initially steep transverse and normal faults propagated upward toward the layered cover rocks. Exposed tilted cross sections, as much as 8 km thick, display transitions from faulted basement to folded cover that validate laboratory models of forced folds. The folded cover masks a deeper extensional style of brittle segmentation and uniform steep tilting.

Howard, Keith A.; John, Barbara E.

1997-03-01

247

Pool-Type Fishways: Two Different Morpho-Ecological Cyprinid Species Facing Plunging and Streaming Flows  

PubMed Central

Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a need to determine optimum dimensioning values and hydraulic parameters. The aim of this work is to study the behaviour and performance of two species with different ecological characteristics (Iberian barbel Luciobarbus bocagei–bottom oriented, and Iberian chub Squalius pyrenaicus–water column) in a full-scale experimental pool-type fishway that offers two different flow regimes–plunging and streaming. Results showed that both species passed through the surface notch more readily during streaming flow than during plunging flow. The surface oriented species used the surface notch more readily in streaming flow, and both species were more successful in moving upstream in streaming flow than in plunging flow. Streaming flow enhances upstream movement of both species, and seems the most suitable for fishways in river systems where a wide range of fish morpho-ecological traits are found.

Branco, Paulo; Santos, Jose M.; Katopodis, Christos; Pinheiro, Antonio; Ferreira, Maria T.

2013-01-01

248

The method of assessment of the grinding wheel cutting ability in the plunge grinding  

NASA Astrophysics Data System (ADS)

This article presents the method of comparative assessment of the grinding wheel cutting ability in the plunge grinding kinematics. A new method has been developed to facilitate multicriterial assessment of the working conditions of the abrasive grains and the bond bridges, as well as the wear mechanisms of the GWAS, which occur during the grinding process, with simultaneous limitation of the workshop tests range. The work hereby describes the methodology of assessment of the grinding wheel cutting ability in a short grinding test that lasts for 3 seconds, for example, with a specially shaped grinding wheel, in plunge grinding. The grinding wheel macrogeometry modification applied in the developed method consists in forming a cone or a few zones of various diameters on its surface in the dressing cut. It presents an exemplary application of two variants of the method in the internal cylindrical plunge grinding, in 100Cr6 steel. Grinding wheels with microcrystalline corundum grains and ceramic bond underwent assessment. Analysis of the registered machining results showed greater efficacy of the method of cutting using a grinding wheel with zones of various diameters. The method allows for comparative tests upon different grinding wheels, with various grinding parameters and different machined materials.

Nadolny, Krzysztof

2012-09-01

249

Laboratory observations of flow and sediment transport induced by plunging regular waves  

NASA Astrophysics Data System (ADS)

Two parallel experiments involving the evolution and runup induced by plunging regular waves near the shoreline of a sloping bed are considered: (1) a rigid-bed experiment, allowing direct (hot film) measurements of bed shear stresses and (2) a sediment-bed experiment, allowing for the measurement of pore-water pressures as well as observation of sediment suspension and bed morphological changes. Both experiments utilize the same initial bed profile and wave forcing. The experiments show that the mean bed shear stresses experienced onshore of incipient breaking are amplified by nearly a factor of 2 relative to prebreaking conditions, whereas their corresponding turbulent fluctuations are amplified even more strongly, by a factor of 5-6. The plunging processes lead to a series of vortices, whose formation may be explained as the result of shear layer instability. Measurements show that these vortices can significantly enhance peaks in the offshore-directed bed shear stresses. Moreover, near-bed pore pressure measurements indicate that these vortices cause large upward-directed pressure gradients, which in turn produce a corresponding series of suspended sediment plumes shoreward of the initial breaking event. These findings are related to the induced morphological changes over both short and long time scales. The present results are also compared and contrasted with previous experiments utilizing a similar methodology, but involving plunging solitary waves.

Sumer, B. Mutlu; Guner, H. Anil Ari; Hansen, Nilas Mandrup; Fuhrman, David R.; Fredsøe, Jørgen

2013-11-01

250

Surf-generated noise signatures: A comparison of plunging and spilling breakers  

NASA Astrophysics Data System (ADS)

Range-time-frequency distributions of surf-generated noise were measured within the surf zone during the SandyDuck'97 experiment at Duck, NC. A 24-phone, 138-m, bottom-mounted, linear array located along a line perpendicular to the shore at a depth of 1 to 3 m recorded the surf-generated noise. Concurrent video measurements of the location, size, and time-evolution of the individual breaking waves directly above the array were made from a nearby 43-m tower. Source level spectra are obtained by using a modified fast field program to account for water column and geoacoustic propagation from the distributed source region to an individual hydrophone. The length, location, and orientation of the leading edge of breakers are tracked in time from rectified video images. It is observed that the source levels from spilling breakers are lower (approx5-10 dB) than those produced by plunging breakers that occurred during the same time period. Plunging breakers generated time-frequency signatures with a sharp onset while spilling breakers' signatures had a gradual low-frequency precursor. Range-time signatures of plunging breakers indicate a burst of acoustic energy while spilling breakers' signatures depict sound being generated over a longer time period with the source region moving with the breaking surface wave.

Means, Steven L.; Heitmeyer, Richard M.

2002-08-01

251

Simultaneous analysis of dopamine and homovanillic acid by high-performance liquid chromatography with wall-jet/thin-layer electrochemical detection.  

PubMed

Wall-jet/thin-layer amperometric electrochemical detection (ECD) coupled with high-performance liquid chromatography (HPLC) was used here for the simultaneous analysis of dopamine (DA) and homovanillic acid (HVA) at a glassy carbon electrode. Compared with the conventional thin-layer mode and wall-jet mode, the presented wall-jet/thin-layer ECD has the advantages of enhanced capture of electroactive DA and HVA on the working electrode to give enhanced responses and more convenient washing/refreshment of the working electrode surface. Under optimized conditions, the HPLC-ECD calibration curves show good linearity from 0.01 to 100 ?M for DA and HVA, and the limits of detection (LODs) obtained were 1.1 nM for DA and 0.7 nM for HVA which are lower than those obtained with an UV-vis detector and a commercial electrochemical detector. The method was tested on human urine with satisfactory results. The balance of response-signal, signal-background and noise level for our HPLC-ECD system is also discussed. In addition, a demethylation electrooxidation mechanism for HVA is suggested through potentiostatic bulk electrolysis, electrospray ionization-mass spectrometry, fluorescent spectrophotometry and cyclic voltammetry studies. PMID:24116372

Zhou, Yaping; Yan, Hongling; Xie, Qingji; Huang, Siyu; Liu, Jiali; Li, Zou; Ma, Ming; Yao, Shouzhuo

2013-12-01

252

Comparison of propagation- and grating-based x-ray phase-contrast imaging techniques with a liquid-metal-jet source  

NASA Astrophysics Data System (ADS)

X-ray phase-contrast imaging has been developed as an alternative to conventional absorption imaging, partly for its dose advantage over absorption imaging at high resolution. Grating-based imaging (GBI) and propagation-based imaging (PBI) are two phase-contrast techniques used with polychromatic laboratory sources. We compare the two methods by experiments and simulations with respect to required dose. A simulation method based on the projection approximation is designed and verified with experiments. A comparison based on simulations of the doses required for detection of an object with respect to its diameter is presented, showing that for monochromatic radiation, there is a dose advantage for PBI for small features but an advantage for GBI at larger features. However, GBI suffers more from the introduction of polychromatic radiation, in this case so much that PBI gives lower dose for all investigated feature sizes. Furthermore, we present and compare experimental images of biomedical samples. While those support the dose advantage of PBI, they also highlight the GBI advantage of quantitative reconstruction of multimaterial samples. For all experiments a liquid-metal-jet source was used. Liquid-metal-jet sources are a promising option for laboratory-based phase-contrast imaging due to the relatively high brightness and small spot size.

Zhou, T.; Lundström, U.; Thüring, Thomas; Rutishauser, S.; Larsson, D. H.; Stampanoni, M.; David, C.; Hertz, H. M.; Burvall, A.

2014-03-01

253

Production of jet fuels from coal-derived liquids. Volume 2. Characterization of liquid by-products from the Great Plains Gasification Plant. Interim report, 26 November 1986-1 February 1988  

SciTech Connect

The Great Plains Gasification Plant (GPGP) represents the first commercial Syn-Fuels Plant in the United States. The GPGP produces three by-product hydrocarbon liquid streams (rectisol naphtha, crude phenol and tar oil) which are utilized as plant fuel. The purpose of this work was to characterize these streams in order to more fully understand what would be necessary to produce jet fuel or other more valuable products from these streams. The rectisol naphtha is mostly benzene-toluene-xylene (BTX) material. In the raw form it has a strong odor that can be reduced by sweetening and contains very volatile components including acetone and pentadienes.

Knudson, C.L.

1988-05-01

254

Twin Jet  

NASA Technical Reports Server (NTRS)

Many subsonic and supersonic vehicles in the current fleet have multiple engines mounted near one another. Some future vehicle concepts may use innovative propulsion systems such as distributed propulsion which will result in multiple jets mounted in close proximity. Engine configurations with multiple jets have the ability to exploit jet-by-jet shielding which may significantly reduce noise. Jet-by-jet shielding is the ability of one jet to shield noise that is emitted by another jet. The sensitivity of jet-by-jet shielding to jet spacing and simulated flight stream Mach number are not well understood. The current experiment investigates the impact of jet spacing, jet operating condition, and flight stream Mach number on the noise radiated from subsonic and supersonic twin jets.

Henderson, Brenda; Bozak, Rick

2010-01-01

255

Measurements of vaporized and liquid fuel concentration fields in a burning spray jet of acetone using planar laser induced fluorescence  

Microsoft Academic Search

Planar LIF of acetone has been performed in the near development field of a burning spray jet. The main difficulty of such investigations comes from the large range of signal levels provided by the vapor and the size dispersed spray, which cannot be covered by the camera dynamics. The key point of the present work lies in a strong compression

R. Bazile; D. Stepowski

1995-01-01

256

Production of jet fuel from coal-derived liquids. Quarterly technical progress report No. 25, October 1-December 31, 1988.  

National Technical Information Service (NTIS)

Amoco and Lummus-Crest, under a contract with the United States Department of Energy, are evaluating the process options and economics for upgrading the naphtha, crude phenols, and tar oil by-products from the Great Plains Coal Gasification Plant to jet f...

M. W. Furlong J. D. Fox J. G. Masin

1988-01-01

257

Numerical heat transfer during partially-confined, confined, and free liquid jet impingement with rotation and chemical mechanical planarization process modeling  

NASA Astrophysics Data System (ADS)

This work presents the use of numerical modeling for the analysis of transient and steady state liquid jet impingement for cooling application of electronics, and energy dissipation during a CMP process under the influence of a series of parameters that controls the transport phenomena mechanism. Seven thorough studies were done to explore how the flow structure and conjugated heat transfer in both the solid and fluid regions was affected by adding a secondary rotational flow during the jet impingement process. Axis-symmetrical numerical models of round jets with a spinning or static nozzle were developed using the following configurations: confined, partially-confined, and free liquid jet impingement on a rotating or stationary uniformly heated disk of finite thickness and radius. Calculations were done for various materials, namely copper, silver, Constantan, and silicon with a solid to fluid thermal conductivity ratio covering a range of 36.91.2222, at different laminar Reynolds numbers ranging from 220 to 2,000, under a broad rotational rate range of 0 to 1,000 RPM (Ekman number=infinity--3.31x10--5), nozzle-to-plate spacing (beta=0.25.5.0), dimensionless disk thicknesses (b/dn=0.167.1.67), confinement ratio (rp/rd=0.2.0.75), and Prandtl number (1.29.124.44) using NH3, H2O, FC.77 and MIL.7808 as working fluids. An engineering correlation relating the average Nusselt number with the above parameters was developed for the prediction of system performance. The simulation results compared reasonably well with previous experimental studies. The second major contribution of this research was the development of a three dimensional CMP model that shows the temperature distributions profile as an index of energy dissipation at the wafer and pad surfaces, and slurry interface. A finite element analysis was done with FIDAP 8.7.4 package under the influence of physical parameters, such as slurry flow rates (0.5.1.42 cc/s), polishing pressures (17.24.41.37 kPa), pad spinning rates (100.250 RPM), carrier spinning rates (15.75 RPM), and slurry film thicknesses (40.200 mum). Results in this study provide further insight of how the above parameters influence the thermal aspects of pad and wafer temperature and heat transfer coefficients distributions across the control volume under study. Numerical results support the interpretation of the experimental data.

Lallave Cortes, Jorge C.

258

Jet Substructure  

NASA Astrophysics Data System (ADS)

Jet physics is a rich and rapidly evolving field, with many applications to physics in and beyond the Standard Model. These notes, based on lectures delivered at the June 2012 Theoretical Advanced Study Institute, provide an introduction to jets at the Large Hadron Collider. Topics covered include sequential jet algorithms, jet shapes, jet grooming, and boosted Higgs and top tagging.

Shelton, J.

2013-08-01

259

Plunge Video  

NSDL National Science Digital Library

Seven short animations present a tour under the Pacific Ocean based on real data about the sea floor's peaks and valleys. Visitors submerge near Hawaii, continue as if in a submarine to Japan, and finally dive to the ocean's deepest point in the Marianas Trench, between Japan and New Guinea. The tour is based on bathymetric, topographic, and astronomical data provided by the University of Hawaii and various federal agencies.

Feldman, Gene

260

Numerical simulation of a plunging flexible hydrofoil and its experimental validation  

NASA Astrophysics Data System (ADS)

A monolithic approach for simulation of flexible flapping wings in fully-coupled motion has recently been developed. The methodology is based on a uniform description of fluid and structure in Eulerian framework. Immersed boundary technique is used to represent solid stress, solid-fluid interface, and active flapping motion in an overall Cartesian coordinate. In the current presentation, the focus is to apply the method on a simple two-dimensional problem of plunging flexible hydrofoil and then compare to the experimental results for validation. The three-dimensional results and experimental validations will also be discussed.

Yang, Tao; Martin-Alarcon, Leonardo; Wei, Mingjun; Shu, Fangjun

2011-11-01

261

Free swimming of an elastic plate plunging at low Reynolds number  

NASA Astrophysics Data System (ADS)

We use three-dimensional computer simulations to examine the free swimming of an elastic plate plunging sinusoidally in a viscous fluid with a Reynolds number of 250. We find that the free swimming velocity is maximized when the swimmer is driven near the first natural frequency leading to larger swimmer deformations, and that the free swimming velocity is nearly linearly related to the trailing edge displacement. The maximum swimmer performance is found at a non-resonance frequency. The maximum performance takes place when the swimmer exhibits a deformation pattern in which the transverse displacement of the swimmer's center of mass is minimized, which in turn reduces viscous losses.

Yeh, Peter Derek; Alexeev, Alexander

2014-05-01

262

Finite element analysis and computer graphics visualization of flow around pitching and plunging airfoils  

NASA Technical Reports Server (NTRS)

A general computational method for analyzing unsteady flow around pitching and plunging airfoils was developed. The finite element method was applied in developing an efficient numerical procedure for the solution of equations describing the flow around airfoils. The numerical results were employed in conjunction with computer graphics techniques to produce visualization of the flow. The investigation involved mathematical model studies of flow in two phases: (1) analysis of a potential flow formulation and (2) analysis of an incompressible, unsteady, viscous flow from Navier-Stokes equations.

Bratanow, T.; Ecer, A.

1973-01-01

263

Jet shielding of jet noise  

NASA Technical Reports Server (NTRS)

An experimental and theoretical study was conducted to develop a validated first principle analysis for predicting the jet noise reduction achieved by shielding one jet exhaust flow with a second, closely spaced, identical jet flow. A generalized fuel jet noise analytical model was formulated in which the acoustic radiation from a source jet propagates through the velocity and temperature discontinuity of the adjacent shielding jet. Input variables to the prediction procedure include jet Mach number, spacing, temperature, diameter, and source frequency. Refraction, diffraction, and reflection effects, which control the dual jet directivity pattern, are incorporated in the theory. The analysis calculates the difference in sound pressure level between the dual jet configuration and the radiation field based on superimposing two independent jet noise directivity patterns. Jet shielding was found experimentally to reduce noise levels in the common plane of the dual jet system relative to the noise generated by two independent jets.

Simonich, J. C.; Amiet, R. K.; Schlinker, R. H.

1986-01-01

264

Analytical and computational investigations of airfoils undergoing high-frequency sinusoidal pitch and plunge motions at low Reynolds numbers  

NASA Astrophysics Data System (ADS)

Current interests in Micro Air Vehicle (MAV) technologies call for the development of aerodynamic-design tools that will aid in the design of more efficient platforms that will also have adequate stability and control for flight in gusty environments. Influenced largely by nature MAVs tend to be very small, have low flight speeds, and utilize flapping motions for propulsion. For these reasons the focus is, specifically, on high-frequency motions at low Reynolds numbers. Toward the goal of developing design tools, it is of interest to explore the use of elementary flow solutions for simple motions such as pitch and plunge oscillations to predict aerodynamic performance for more complex motions. In the early part of this research, a validation effort was undertaken. Computations from the current effort were compared with experiments conducted in a parallel, collaborative effort at the Air Force Research Laboratory (AFRL). A set of pure-pitch and pure-plunge sinusoidal oscillations of the SD7003 airfoil were examined. Phase-averaged measurements using particle image velocimetry in a water tunnel were compared with computations using two flow solvers: (i) an incompressible Navier-Stokes Immersed Boundary Method and (ii) an unsteady compressible Reynolds-Averaged Navier-Stokes (RANS) solver. The motions were at a reduced frequency of k = 3.93, and pitch-angle amplitudes were chosen such that a kinematic equivalence in amplitudes of effective angle of attack (from plunge) was obtained. Plunge cases showed good qualitative agreement between computation and experiment, but in the pitch cases, the wake vorticity in the experiment was substantially different from that predicted by both computations. Further, equivalence between the pure-pitch and pure-plunge motions was not attained through matching effective angle of attack. With the failure of pitch/plunge equivalence using equivalent amplitudes of effective angle of attack, the effort shifted to include pitch-rate and wake-effect terms through the use of analytical methods including quasi-steady thin-airfoil theory (QSTAT) and Theodorsen's theory. These theories were used to develop three analytical approaches for determining pitch motions equivalent to plunge motions. A study of variation in plunge height was then examined and followed by a study of the effect of rotation point using the RANS solver. For the range of plunge heights studied, it was observed that kinematic matching between plunge and pitch using QSTAT gave outstanding similarities in flow field, while the matching performed using Theodorsen's theory gave the best equivalence in lift coefficients for all cases. The variation of rotation point revealed that, for the given plunge height, with rotation point in front of the mid-chord location, all three schemes matched flow-field vorticity well, and with rotation point aft of the mid-chord no scheme matched vorticity fields. However, for all rotation points (except for the mid-chord location), CFD prediction of lift coefficients from the Theodorsen matching scheme matched the lift time histories closely to CFD predictions for pure-pitch. Combined pitch and plunge motions were then examined using kinematic parameters obtained from the three schemes. The results showed that QSTAT nearly cancels the vortices emanating from the trailing edge. Theodorsen's matching approach was successful in generating a lift that was close to constant over the entire cycle. Additionally this approach showed the presence of the reverse Karman vortex sheet through the wake. Combined pitch/plunge motions were then analyzed, computationally and experimentally, with a non-zero mean angle of attack. All computational results compared excellently with experiments, capturing vorticity production on the airfoil's surface and through the wake. Lift coefficient through a cycle was shown to tend toward a constant using Theodorsen's parameters, with the constant being dependent on the initial angle of attack. This result points to the possibility of designing an unsteady motion to match a given flig

McGowan, Gregory Z.

265

Lattice Boltzmann simulation of dynamics of plunge and pitch of 3D flexible wing  

NASA Astrophysics Data System (ADS)

The method of lattice Boltzmann (LB) simulation has been used to simulate fluid structures and motion of a flexible insect wing in a 3D space. In the method, a beam has been discretized into a chain of rigid segments. Each segment is connected through ball and socket joints at its ends. One segment may be bent and twisted with its neighboring segment. A constraint force is applied to each joint to ensure the solid structure moving as a whole flexible elastic body.We have demonstrated that the LB method is suitable for modeling of aerodynamics of insects flight at low Reynolds numbers. First, a simulation of plunging and pitching of a rigid wing is performed at Re=75 in a 2D space and the results of lift forces and flow structures are in excellent agreement with the previous results. Second, plunging and pitching of a flexible wing in span-wise direction is simulated at Re=136 in a 3D space. We found that when twisting elasticity is large enough the twisting angle could be controlled at a level of smaller than 0.2 degree. It is shown that as bending and twisting elasticity is large enough, the motion of flexible wing approaches that of a rigid membrane wing. The simulation results show that the optimization of flexibility in span-wise direction will benefit thrust and an intermediate level is favorable. The results are consistent with experimental finding.

Qi, Dewei; Shyy, Wei

2008-11-01

266

Energy Exchange during Plunge/Surge Motions of a 2D Wing  

NASA Astrophysics Data System (ADS)

The rate of energy transfer between an NACA-0006 wing and an unsteady flow is examined at pre-stall and post-stall conditions using numerical simulations and wind tunnel experiments. The plunge and surge motions simulate the fluctuating vertical (wz) and longitudinal (wx) velocity components of a wind gust. In a steady flow the wing loses energy to the flow through the drag power term, but in an unsteady flow the wing may gain energy from the fluctuating lift power and fluctuating drag power terms. The net energy transfer averaged over the period of oscillation depends on the phase angle between the plunge and surge motions. The largest increase of energy occurs when wx and wz are in-phase. When the fluctuations are large enough, then it is possible for the net energy gain to be positive. The numerical simulations conducted at Reynolds numbers near the critical value for vortex shedding show qualitative agreement with the experiments. The simulations highlight the role of vortex shedding in determining the optimal frequency and phase for energy extraction from the gust.

Kerstens, Wesley; Choi, Jeesoon; Colonius, Tim; Williams, David

2011-11-01

267

Jet pump assisted artery  

NASA Technical Reports Server (NTRS)

A procedure for priming an arterial heat pump is reported; the procedure also has a means for maintaining the pump in a primed state. This concept utilizes a capillary driven jet pump to create the necessary suction to fill the artery. Basically, the jet pump consists of a venturi or nozzle-diffuser type constriction in the vapor passage. The throat of this venturi is connected to the artery. Thus vapor, gas, liquid, or a combination of the above is pumped continuously out of the artery. As a result, the artery is always filled with liquid and an adequate supply of working fluid is provided to the evaporator of the heat pipe.

1975-01-01

268

Production of Jet Fuels from Coal-Derived Liquids. Volume 2. Characterization of Liquid By-Products from the Great Plains Gasification Plant.  

National Technical Information Service (NTIS)

The Great Plains Gasification Plant (GPGP) represents the first commercial Syn-Fuels Plant in the United States. The GPGP produces three by-product hydrocarbon liquid streams (rectisol naphtha, crude phenol and tar oil) which are utilized as plant fuel. T...

C. L. Knudson

1988-01-01

269

Evaluation of the sensitivity and response of IR thermography from a transparent heater under liquid jet impingement  

NASA Astrophysics Data System (ADS)

The feasibility of a visible/IR transparent heater and its suitability for IR thermography is experimentally examined. The most common transparent conductive coating, Indium Tin Oxide (ITO), is quite reflective and its optical properties depend on thickness and manufacturing process. Therefore, the optical properties of several thicknesses and types of ITO, coated on an IR window (BaF2), are examined. A highly transparent Cadmium Oxide (CdO) coating on a ZnS window, also examined, is found to be unusable. Transmissivity is found to increase with a decrease in coating thickness, and total emittance is relatively low. A thick ITO coating was examined for IR thermography in the challenging test case of submerged water jet impingement, where temperature differences were characteristically small and distributed. The measurements under steady state conditions were found to agree well with the literature, and the method was validated. Comparison of two IR cameras did not show the LWIR low-temperature advantage, up to the maximal acquisition rate examined, 1.3KHz. Rather the MWIR camera had a stronger signal to noise ratio, due to the higher emissivity of the heater in this range. The transient response of the transparent heater showed no time-delay, though the substrate dampens the thermal response significantly. Therefore, only qualitative transient measurements are shown for the case of pulsating free-surface jet impingement, showing that the motion of the hydraulic jump coincides with thermal measurements. From these results, recommendations are made for coating/window combination in IR thermography.

Haustein, H. D.; Rohlfs, W.; Al-Sibai, F.; Kneer, R.

2012-11-01

270

Coal liquefaction to increase jet fuel production  

NASA Technical Reports Server (NTRS)

Processing concept that increases supply of jet fuel has been developed as part of study on methods for converting coal to hydrogen, methane, and jet fuel. Concept takes advantage of high aromatic content of coal-derived liquids to make high-octane gasoline, instead of destroying aromatics to make jet fuel.

1979-01-01

271

Outflow from a laval nozzle with condensation of the vapor phase on a concomitant jet of cold liquid  

Microsoft Academic Search

The experiments were conducted on a steam-water test rig. The outflow is shown schematically in Fig. 1. The Laval nozzle 1 with central body 2 was similar in design to that described in [ 1 ]. The central body was a thermally insulated liquid nozzle. The mounts of the nozzles lay in plane 3. Beyond the nozzle mouths a cylindrical

S. I. Alad'ev; F. M. Krantov; S. V. Teplov

1980-01-01

272

An archival study of eyewitness memory of the Titanic's final plunge.  

PubMed

A handful of real-life studies demonstrate that most eyewitnesses accurately recall central details (i.e., the gist of what happened) from traumatic events. The authors evaluated the accuracy of archival eyewitness testimony from survivors of the Titanic disaster who witnessed the ship's final plunge. The results indicate that most eyewitness testimony (15 eyewitnesses of 20) is consistent with forensic evidence that demonstrates that the Titanic was breaking apart while it was still on the ocean's surface. Despite the methodological limitations of archival research, the authors provide evidence from a single-occurrence traumatic event (with a large-scale loss of life) that the majority of eyewitnesses accurately recall central details. PMID:12635858

Riniolo, Todd C; Koledin, Myriah; Drakulic, Gregory M; Payne, Robin A

2003-01-01

273

An experimental investigation of air entrainment through viscous liquids in a horizontally rotating cylinder  

NASA Astrophysics Data System (ADS)

Flow patterns produced inside a cylinder partly filled with a viscous liquid and rotated about its horizontal axis of symmetry have been discussed by many authors. We report here on a similar experiment where we have observed new flow patterns at filling fractions >= 50%. We will focus on the production of thin films of air triangular in shape but otherwise similar to those produced in a very different geometry by a viscous jet plunging into a bath, as elucidated by J. Eggers [Phys. Rev. Lett. 86, 19] and E. Lorenceau and D. Quere' [Phys. Rev. Lett. 93, 254501]. Two-dimensional drops of the viscous liquid move inside the thin film as a stable associated feature. As the angular velocity is lowered, the triangular area of the film becomes smaller and smaller until it squeezes the remaining drop into a cusp. Further decrease of the angular velocity causes the film to burst and squeeze the drop out into the surrounding liquid. One final observation unreported elsewhere is the formation of an inverted tear-drop bubble that remains stationary in the apparatus while the liquid rotates at significant speeds.

Carnevali, Antonino

2006-11-01

274

Experimental investigation of radar backscatter from plunging breakers using an ultrawideband radar and visible\\/infrared cameras  

Microsoft Academic Search

Interim results of a laboratory investigation of the low-grazing angle radar backscatter generated by plunging breakers are presented. A primary objective of this investigation is to experimentally verify a scattering mechanism through which the horizontally-polarized backscatter generated by the breaker can exceed that at vertical polarization, without involving multipath propagation between the front face of the wave and its crest.

Mark A. Sletten; Geoff B. Smith; Xinan Liu; James H. Duncan

2004-01-01

275

Vortex diode jet  

DOEpatents

A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

Houck, Edward D. (Idaho Falls, ID)

1994-01-01

276

Jet device for use in wells  

SciTech Connect

This apparatus is for jet cleaning wells having different-diameter casing strings. The apparatus includes an elongated member for running into the well, and a movable member having a jet body for forming a jet connected to the elongated member. The movable member moves out against the casing string responsive to application of jetting liquid between the movable member and the elongated member. 7 claims.

Hutchison, S.O.

1980-04-15

277

Production of jet fuels from coal-derived liquids. Volume 5. Recovery of benzene\\/benzene plus phenol from the Great Pplains Gasification Plant crude phenol stream. Interim report, September 1987February 1988  

Microsoft Academic Search

In September 1986, the Fuels Branch of the Aero Propulsion Laboratory at Wright-Patterson Air Force Base, Ohio, began an investigation of the potential for production of jet fuels from the liquid by-product streams produced by the gasification of lignite at the Great Plains Gasification Plant located in Buelah, North Dakota. Funding was provided to the U.S. Department of Energy (DOE)

1988-01-01

278

Normal stress measurement by means of a jet thrust apparatus  

Microsoft Academic Search

Summary Apparatus is described which enables the normal stress-shear rate behaviour of a viscoelastic liquid to be obtained from observations of the thrust of a jet of the liquid issuing from a capillary tube (or slot). Two types of apparatus are mentioned. In one type the jet thrust is obtained from the impact force on a boat which the jet

D. R. Oliver; W. C. MacSporran

1969-01-01

279

Test Cases for Flutter of the Benchmark Models Rectangular Wings on the Pitch and Plunge Apparatus  

NASA Technical Reports Server (NTRS)

The supercritical airfoil was chosen as a relatively modem airfoil for comparison. The BOO12 model was tested first. Three different types of flutter instability boundaries were encountered, a classical flutter boundary, a transonic stall flutter boundary at angle of attack, and a plunge instability near M = 0.9 and for zero angle of attack. This test was made in air and was Transonic Dynamics Tunnel (TDT) Test 468. The BSCW model (for Benchmark SuperCritical Wing) was tested next as TDT Test 470. It was tested using both with air and a heavy gas, R-12, as a test medium. The effect of a transition strip on flutter was evaluated in air. The B64AOlO model was subsequently tested as TDT Test 493. Some further analysis of the experimental data for the BOO12 wing is presented. Transonic calculations using the parameters for the BOO12 wing in a two-dimensional typical section flutter analysis are given. These data are supplemented with data from the Benchmark Active Controls Technology model (BACT) given and in the next chapter of this document. The BACT model was of the same planform and airfoil as the BOO12 model, but with spoilers and a trailing edge control. It was tested in the heavy gas R-12, and was instrumented mostly at the 60 per cent span. The flutter data obtained on PAPA and the static aerodynamic test cases from BACT serve as additional data for the BOO12 model. All three types of flutter are included in the BACT Test Cases. In this report several test cases are selected to illustrate trends for a variety of different conditions with emphasis on transonic flutter. Cases are selected for classical and stall flutter for the BSCW model, for classical and plunge for the B64AOlO model, and for classical flutter for the BOO12 model. Test Cases are also presented for BSCW for static angles of attack. Only the mean pressures and the real and imaginary parts of the first harmonic of the pressures are included in the data for the test cases, but digitized time histories have been archived. The data for the test cases are available as separate electronic files. An overview of the model and tests is given, the standard formulary for these data is listed, and some sample results are presented.

Bennett, Robert M.

2000-01-01

280

Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina  

NASA Astrophysics Data System (ADS)

Beneath much of the Andes, oceanic lithosphere descends eastward into the mantle at an angle of about 30° (ref. 1). A partially molten region is thought to form in a wedge between this descending slab and the overlying continental lithosphere as volatiles given off by the slab lower the melting temperature of mantle material. This wedge is the ultimate source for magma erupted at the active volcanoes that characterize the Andean margin. But between 28° and 33° S the subducted Nazca plate appears to be anomalously buoyant, as it levels out at about 100km depth and extends nearly horizontally under the continent. Above this `flat slab', volcanic activity in the main Andean Cordillera terminated about 9 million years ago as the flattening slab presumably squeezed out the mantle wedge. But it is unknown where slab volatiles go once this happens, and why the flat slab finally rolls over to descend steeply into the mantle 600km further eastward. Here we present results from a magnetotelluric profile in central Argentina, from which we infer enhanced electrical conductivity along the eastern side of the plunging slab, indicative of the presence of partial melt. This conductivity structure may imply that partial melting occurs to at least 250km and perhaps to more than 400km depth, or that melt is supplied from the 410km discontinuity, consistent with the transition-zone `water-filter' model of Bercovici and Karato.

Booker, John R.; Favetto, Alicia; Pomposiello, M. Cristina

2004-05-01

281

Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina.  

PubMed

Beneath much of the Andes, oceanic lithosphere descends eastward into the mantle at an angle of about 30 degrees (ref. 1). A partially molten region is thought to form in a wedge between this descending slab and the overlying continental lithosphere as volatiles given off by the slab lower the melting temperature of mantle material. This wedge is the ultimate source for magma erupted at the active volcanoes that characterize the Andean margin. But between 28 degrees and 33 degrees S the subducted Nazca plate appears to be anomalously buoyant, as it levels out at about 100 km depth and extends nearly horizontally under the continent. Above this 'flat slab', volcanic activity in the main Andean Cordillera terminated about 9 million years ago as the flattening slab presumably squeezed out the mantle wedge. But it is unknown where slab volatiles go once this happens, and why the flat slab finally rolls over to descend steeply into the mantle 600 km further eastward. Here we present results from a magnetotelluric profile in central Argentina, from which we infer enhanced electrical conductivity along the eastern side of the plunging slab, indicative of the presence of partial melt. This conductivity structure may imply that partial melting occurs to at least 250 km and perhaps to more than 400 km depth, or that melt is supplied from the 410 km discontinuity, consistent with the transition-zone 'water-filter' model of Bercovici and Karato. PMID:15164059

Booker, John R; Favetto, Alicia; Pomposiello, M Cristina

2004-05-27

282

Volumetric measurements and simulations of the vortex structures generated by low aspect ratio plunging wings  

NASA Astrophysics Data System (ADS)

Volumetric three-component velocimetry measurements have been performed on low aspect ratio wings undergoing a small amplitude pure plunging motion. This study focuses on the vortex flows generated by rectangular and elliptical wings set to a fixed geometric angle of attack of ? = 20°. An investigation into the effect of Strouhal number illustrates the highly three-dimensional nature of the leading edge vortex as well as its inherent ability to improve lift performance. Computational simulations show good agreement with experimental results, both demonstrating the complex interaction between leading, trailing, and tip vortices generated in each cycle. The leading edge vortex, in particular, may deform significantly throughout the cycle, in some cases developing strong spanwise undulations. These are at least both Strouhal number and planform dependent. One or two arch-type vortical structures may develop, depending on the aspect ratio and Strouhal number. At sufficiently high Strouhal numbers, a tip vortex ring may also develop, propelling itself away from the wing in the spanwise direction due to self-induced velocity.

Calderon, D. E.; Wang, Z.; Gursul, I.; Visbal, M. R.

2013-06-01

283

Experimental study of the boundary layer over an airfoil in plunging motion  

NASA Astrophysics Data System (ADS)

This is an experimental study on the boundary layer over an airfoil under steady and unsteady conditions. It specifically deals with the effect of plunging oscillation on the laminar/turbulent characteristics of the boundary layer. The wind tunnel measurements involved surfacemounted hot-film sensors and boundary-layer rake. The experiments were conducted at Reynolds numbers of 0.42×106 to 0.84 × 106 and the reduced frequency was varied from 0.01 to 0.11. The results of the quasi-wall-shear stress as well as the boundary layer velocity profiles provided important information about the state of the boundary layer over the suction surface of the airfoil in both static and dynamic cases. For the static tests, boundary layer transition occurred through a laminar separation bubble. By increasing the angle of attack, disturbances and the transition location moved toward the leading edge. For the dynamic tests, earlier transition occurred with increasing rather than decreasing effective angle of attack. The mean angle of attack and the oscillating parameters significantly affected the state of the boundary layer. By increasing the reduced frequency, the boundary layer transition was promoted to the upstroke portion of the equivalent angle of attack, but the quasi skin friction coefficient was decreased.

Marzabadi, F. Rasi; Soltani, M. R.

2012-04-01

284

The Development of Gullies on the Landscape: a Model of Headcut Retreat Resulting From Plunge Pool Erosion  

NASA Astrophysics Data System (ADS)

Head advance due to plunge-pool erosion is a common process in gullies incising resistant soils. A model of headcut retreat resulting from plunge-pool erosion is developed and implemented in CHILD, an existing 3D landscape evolution modeling framework. The model estimates horizontal headcut retreat as a function of discharge, height of the headcut, upstream slope and relevant land surface and soil properties for soil erosion. The physical model results compare well with the published data from flume experiments. We analyzed the sensitivity of headcut retreat to flow discharge, upstream slope and surface roughness, and headcut height. CHILD simulations indicate that headcut retreat is most significant in zones with either gentle slopes or large headcut heights. Model parameters have contrasting effects on the retreat rates depending on the size and depth of the pool beneath the headcut, and upstream flow hydraulics, making the process difficult to predict as a function of topographic thresholds and simple geomorphic transport laws.

Flores Cervantes, J. H.; Istanbulluoglu, E.; Bras, R.

2004-12-01

285

Production of jet fuels from coal-derived liquids. Volume 12. Preliminary process design and cost estimate and production-run recommendation. Final report, March-December 1989  

Microsoft Academic Search

A preliminary design for the production of JP-8 jet fuel and other salable products from the Great Plains by-products is given. The design incorporates experimental results from Tasks 2 and 3 with the scoping design from Task 1. The experimental results demonstrated the need for more severe hydrotreating conditions to convert the tar oil to jet fuel than was estimated

M. Furlong; J. Fox; J. Masin; E. Stahlnecker; G. Schreiber

1989-01-01

286

Quantitative analysis of the dripping and jetting regimes in co-flowing capillary jets  

Microsoft Academic Search

We study a liquid jet that breaks up into drops in an external co-flowing\\u000aliquid inside a confining microfluidic geometry. The jet breakup can occur\\u000aright after the nozzle in a phenomenon named dripping or through the generation\\u000aof a liquid jet that breaks up a long distance from the nozzle, which is called\\u000ajetting. Traditionally, these two regimes have

María Luisa Cordero; François Gallaire; Charles N. Baroud

2010-01-01

287

Gravitomagnetic jets  

SciTech Connect

We present a family of dynamic rotating cylindrically symmetric Ricci-flat gravitational fields whose geodesic motions have the structure of gravitomagnetic jets. These correspond to helical motions of free test particles up and down parallel to the axis of cylindrical symmetry and are reminiscent of the motion of test charges in a magnetic field. The speed of a test particle in a gravitomagnetic jet asymptotically approaches the speed of light. Moreover, numerical evidence suggests that jets are attractors. The possible implications of our results for the role of gravitomagnetism in the formation of astrophysical jets are briefly discussed.

Chicone, C.; Mashhoon, B. [Department of Mathematics and Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States); Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 (United States)

2011-03-15

288

Diffractive jets  

SciTech Connect

The properties of particle clusters produced in the processes of single and double diffraction dissociation of protons at high energies are reviewed. These clusters appear as jets close to the direction of the dissociating protons and are referred to as diffractive or forward jets. (GHT)

Goulianos, K.

1982-01-01

289

Jet impact on a soap film.  

PubMed

We experimentally investigate the impact of a liquid jet on a soap film. We observe that the jet never breaks the film and that two qualitatively different steady regimes may occur. The first one is a refractionlike behavior obtained at small incidence angles when the jet crosses the film and is deflected by the film-jet interaction. For larger incidence angles, the jet is absorbed by the film, giving rise to a new class of flows in which the jet undulates along the film with a characteristic wavelength. Besides its fundamental interest, this paper presents a different way to guide a micrometric flow of liquid in the inertial regime and to probe foam stability submitted to violent perturbations at the soap film scale. PMID:23031009

Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

2012-09-01

290

Vortex diode jet performance and theory  

SciTech Connect

Fluidics is the technology dealing with the use of a flowing liquid or gas in various devices for controls and fluid transfers. Existing fluidic technology transfers fluid at approximately the same rate as air lifts and jets. A vortex diode combined in parallel with a jet (vortex diode jet) produces significantly higher transfer rates` and retains the fluidic system advantages. This paper presents the proof of concept research and gives design parameters for the vortex diode jet. The goal of this research was to develop a vortex diode jet that would improve fluidic system transfer rates, and to develop and verify the,design equations. Proven design equations could then be used to design, and model vortex diode jet systems. This research has shown that vortex diode jets improve fluidic system transfer rate by up to 60 percent and can be modelled with the design equations.

Houck, E.D.

1993-12-01

291

Taking the Plunge: Next Steps in Engaged Learning: Project Kaleidoscope-Connecticut Conference of Independent Colleges Conference for Science Educators.  

PubMed

College and university science educators from across Connecticut gathered at Yale's West Campus in April 2010 for a Project Kaleidoscope (PKAL) program entitled "Taking the Plunge: Next Steps in Engaged Learning." Funded by the National Science Foundation (NSF) and co-sponsored by the Connecticut Conference of Independent Colleges (CCIC) and Yale's McDougal Graduate Teaching Center, the event was the latest in a PKAL series of one-day conferences aimed at equipping science, technology, engineering, and math (STEM) instructors with effective approaches to engaging students and training future scientists. PMID:20885897

Frederick, Jennifer

2010-09-01

292

Modeling droplet size distribution from impinging jets  

Microsoft Academic Search

A mathematical formulation developed for fan-spray nozzles is applied to the sheet formed by two impinging jets. The results obtained in a study concerning thickness distribution in a sheet formed by impinging jets are merged with those of an analysis of the aerodynamic instability and disintegration of viscous liquid sheets to allow a proper formulation in order to calculate the

H. S. Couto; D. Bastos-Netto

1991-01-01

293

Concentration Distributions during Pulse Jet Mixing  

Microsoft Academic Search

Obtaining real-time, in situ slurry concentration measurements during unsteady mixing can provide increased understanding into mixer performance. During recent tests an ultrasonic attenuation sensor was inserted into a mixing vessel to measure the slurry concentration during unsteady mixing in real time during pulse jet mixer operation. These pulse jet mixing tests to suspend noncohesive solids in Newtonian liquid were conducted

Judith A. Bamberger; Perry A. Meyer

2010-01-01

294

Analysis of non-linear aeroelastic response of a supersonic thick fin with plunging, pinching and flapping free-plays  

NASA Astrophysics Data System (ADS)

The flutter of a 3-D rigid fin with double-wedge section and free-play in flapping, plunging and pitching degrees-of-freedom operating in supersonic and hypersonic flight speed regimes have been considered. Aerodynamic model is obtained by local usage of the piston theory behind the shock and expansion analysis, and structural model is obtained based on Lagrange equation of motion. Such model presents fast, accurate algorithm for studying the aeroelastic behavior of the thick supersonic fin in time domain. Dynamic behavior of the fin is considered over large number of parameters that characterize the aeroelastic system. Results show that the free-play in the pitching, plunging and flapping degrees-of-freedom has significant effects on the oscillation exhibited by the aeroelastic system in the supersonic/hypersonic flight speed regimes. The simulations also show that the aeroelastic system behavior is greatly affected by some parameters, such as the Mach number, thickness, angle of attack, hinge position and sweep angle.

Firouz-Abadi, R. D.; Alavi, S. M.; Salarieh, H.

2013-07-01

295

Spray formation by like-doublet impinging jets in low speed cross-flows  

Microsoft Academic Search

Breakup and spray formation by impinging liquid jets introduced into a low-speed cross-flow are experimentally investigated.\\u000a Effects of the cross-flows on the macroscopic and microscopic spray parameters are optically measured in terms of jet Weber\\u000a number and liquid-to-gas momentum ratio. The liquid stream undergoes Rayleigh jet breakup at lower jet Weber numbers and bag\\/plume\\u000a breakup at higher momentum ratio through

S. S. Lee; W. H. Kim; W. S. Yoon

2009-01-01

296

Impact of a hydroabrasive jet on material: Hydroabrasive wear  

NASA Astrophysics Data System (ADS)

The wear of steel plates under the impact of a hydroabrasive jet was studied experimentally by varying the distance between the sample surface and the nozzle, the angle of impingement of the jet on the plate, and the abrasive concentrations in water and in the ambient medium (jet in air, submerged jet). The results are compared with available data on the structure of the jet and jet flow around an obstacle. It is shown that the addition of abrasive particles to the liquid can be used to study the liquid jet flow around an obstacle because the form of surface wear allows one to determine the region of impact of the jet core, the deceleration region, and the near-wall flow region before flow separation.

Shtertser, A. A.; Grinberg, B. E.

2013-05-01

297

Intrinsically Pulsating Electrohydrodynamic Cone-Jets  

NASA Astrophysics Data System (ADS)

When the flow rate of an electrohydrodynamic cone-jet is self-regulated, the jet typically pulsates intrinsically due to the imbalance between the liquid supplied to the cone and that discharged through the jet. We used high-speed microscopic imaging and oscilloscopic current measurements to characterize these intrinsic pulsations. The measured kHz-range pulsation frequency compares favorably to a model we developed drawing an analogy between pulsating cone-jet on a supported meniscus and that on an isolated charged drop. The scaling law is expected to be applicable to electrohydrodynamic drop formation and miniaturized electrospray systems.

Chiang, Menghan; Xu, Shenren; Chen, Chuan-Hua

2008-11-01

298

Gas-Jet Levitation Furnace  

NASA Technical Reports Server (NTRS)

Gas jet levitates solid and viscous liquid spheroids at high temperatures in new contactless processing system. System can be used to observe high temperature transformations (for example, crystallization without contact with another solid surface) or in containerless studies to eliminate contamination by crucible.

Ethridge, E. C.; Johnson, J. L.; Dunn, S. A.; Paquette, E. G.

1982-01-01

299

Synthetic Jets  

NASA Technical Reports Server (NTRS)

Current investigation of synthetic jets and synthetic jets in cross-flow examined the effects of orifice geometry and dimensions, momentum-flux ratio, cluster of orifices, pitch and yaw angles as well as streamwise development of the flow field. This comprehensive study provided much needed experimental information related to the various control strategies. The results of the current investigation on isolated and clustered synthetic jets with and without cross-flow will be further analyzed and documented in detail. Presentations at national conferences and publication of peer- reviewed journal articles are also expected. Projected publications will present both the mean and turbulent properties of the flow field, comparisons made with the data available in an open literature, as well as recommendations for the future work.

Milanovic, Ivana M.

2003-01-01

300

Inner Jet Spread Angles of Coaxial Jets from Subcritical to Supercritical Conditions with Preliminary Numerical Results.  

National Technical Information Service (NTIS)

A study is performed to analyze the behavior of the inner jet spread angles in a coaxial jet flow configuration similar to those used in liquid rocket engines. These angles are measured from back-lit images. Data is presented for sub-, near-, and supercri...

D. Talley H. Lyu I. A. Leyva J. I. Rodriguez J. J. Graham

2008-01-01

301

Gas Jets  

NASA Technical Reports Server (NTRS)

A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of the same independent variables as Molenbroek used, but it is found to be more suitable to consider other functions. The stream function and velocity potential corresponding to the problem are given in the form of series. The investigation on the convergence of these series in connection with certain properties of the functions entering them forms the subject of part II. In part III the problem of the outflow of a gas from an infinite vessel with plane walls is solved. In part IV the impact of a gas jet on a plate is considered and the limiting case where the jet expands to infinity changing into a gas flow is taken up in more detail. This also solved the equivalent problem of the resistance of a gaseous medium to the motion of a plate. Finally, in part V, an approximate method is presented that permits a simpler solution of the problem of jet flows in the case where the velocities of the gas (velocities of the particles in the gas) are not very large.

Chaplygin, S.

1944-01-01

302

Gas Jets.  

National Technical Information Service (NTIS)

A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of t...

S. Chaplygin

2003-01-01

303

U.S., non-U.S. outlays to rise in `98, but oil price plunge clouds spending outlook  

SciTech Connect

Capital spending by oil and gas companies in and outside the US will rise in 1998, but that forecast may be jeopardized by the continuing plunge in oil prices. For operations in the US, oil and gas company capital spending is expected to move up in 1998 for the fourth year in a row. If the money is spent, it will be the highest industry investment level since 1985. Strong oil and gas prices and increased volumes have boosted company cash flow and profits the last few years, fueling increased spending. However, the near-term outlook has now been clouded by economic turmoil in a number of Asian countries and the recent collapse of oil prices. The paper discusses oil and gas prices, US upstream spending, US non-exploration and production spending, capital spending in Canada, and spending outside US and Canada.

Beck, R.J.

1998-03-23

304

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed.

Larson, Loren L. (Idaho Falls, ID)

1987-01-01

305

Liquid sampling system  

DOEpatents

A conduit extends from a reservoir through a sampling station and back to the reservoir in a closed loop. A jet ejector in the conduit establishes suction for withdrawing liquid from the reservoir. The conduit has a self-healing septum therein upstream of the jet ejector for receiving one end of a double-ended cannula, the other end of which is received in a serum bottle for sample collection. Gas is introduced into the conduit at a gas bleed between the sample collection bottle and the reservoir. The jet ejector evacuates gas from the conduit and the bottle and aspirates a column of liquid from the reservoir at a high rate. When the withdrawn liquid reaches the jet ejector the rate of flow therethrough reduces substantially and the gas bleed increases the pressure in the conduit for driving liquid into the sample bottle, the gas bleed forming a column of gas behind the withdrawn liquid column and interrupting the withdrawal of liquid from the reservoir. In the case of hazardous and toxic liquids, the sample bottle and the jet ejector may be isolated from the reservoir and may be further isolated from a control station containing remote manipulation means for the sample bottle and control valves for the jet ejector and gas bleed. 5 figs.

Larson, L.L.

1984-09-17

306

Calibrated single-plunge bipolar electrode array for mapping myocardial vector fields in three dimensions during high-voltage transthoracic defibrillation  

Microsoft Academic Search

Mapping of the myocardial scalar electric potential during defibrillation is normally performed with unipolar electrodes connected to voltage dividers and a global potential reference. Unfortunately, vector potential gradients that are calculated from these data tend to exhibit a high sensitivity to measurement errors. This paper presents a calibrated single-plunge bipolar electrode array (EA) that avoids the error sensitivity of unipolar

O. Carlton Deale; Kwong T. Ng; Ellen J. Kim-Van Housen; Bruce B. Lerman

2001-01-01

307

Turbulent Jets?  

NASA Astrophysics Data System (ADS)

Over the last few years we have fielded numerous supersonic jet experiments on the NOVA and OMEGA lasers and Sandia's pulsed-power Z-machine in a collaboration between Los Alamos National Laboratory, the Atomic Weapons Establishment, Lawrence Livermore National Laboratory, and Sandia National Laboratory. These experiments are being conducted to help validate our radiation-hydrodynamic codes, especially the newly developing ASC codes. One of the outstanding questions is whether these types of jets should turn turbulent given their high Reynolds number. Recently we have modified our experiments to have more Kelvin-Helmholtz shear, run much later in time and therefore have a better chance of going turbulent. In order to diagnose these large (several mm) jets at very late times ( 1000 ns) we are developing point-projection imaging on both the OMEGA laser, the Sandia Z-Machine, and ultimately at NIF. Since these jets have similar Euler numbers to jets theorized to be produced in supernovae explosions, we are also collaborating with the astrophysics community to help in the validation of their new codes. This poster will present a review of the laser and pulsed-power experiments and a comparison of the data to simulations by the codes from the various laboratories. We will show results of simulations wherein these jets turn highly 3-dimensional and show characteristics of turbulence. With the new data, we hope to be able to validate the sub-grid-scale turbulent mix models (e. g. BHR) that are being incorporated into our codes.*This work is performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory Laboratory under Contract No. W-7405-ENG-36, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48, the Laboratory for Laser Energetics under Contract No. DE-FC03-92SF19460, Sandia National Laboratories under Contract No. DE-AC04-94AL85000, the Office of Naval Research, and the NASA Astrophysical Theory Grant.

Wilde, B. H.; Rosen, P. A.; Foster, J. M.; Perry, T. S.; Steinkamp, M. J.; Robey, H. F.; Khokhlov, A. M.; Gittings, M. L.; Coker, R. F.; Keiter, P. A.; Knauer, J. P.; Drake, R. P.; Remington, B. A.; Bennett, G. R.; Sinars, D. B.; Campbell, R. B.; Mehlhorn, T. A.

2003-10-01

308

Experimental study of elliptical jet from sub to supercritical conditions  

NASA Astrophysics Data System (ADS)

The jet mixing at supercritical conditions involves fluid dynamics as well as thermodynamic phenomena. All the jet mixing studies at critical conditions to the present date have focused only on axisymmetric jets. When the liquid jet is injected into supercritical environment, the thermodynamic transition could be well understood by considering one of the important fluid properties such as surface tension since it decides the existence of distinct boundary between the liquid and gaseous phase. It is well known that an elliptical liquid jet undergoes axis-switching phenomena under atmospheric conditions due to the presence of surface tension. The experimental investigations were carried out with low speed elliptical jet under supercritical condition. Investigation of the binary component system with fluoroketone jet and N2 gas as environment shows that the surface tension force dominates for a large downstream distance, indicating delayed thermodynamic transition. The increase in pressure to critical state at supercritical temperature is found to expedite the thermodynamic transition. The ligament like structures has been observed rather than droplets for supercritical pressures. However, for the single component system with fluoroketone jet and fluoroketone environment shows that the jet disintegrates into droplets as it is subjected to the chamber conditions even for the subcritical pressures and no axis switching phenomenon is observed. For a single component system, as the pressure is increased to critical state, the liquid jet exhibits gas-gas like mixing behavior and that too without exhibiting axis-switching behavior.

Muthukumaran, C. K.; Vaidyanathan, Aravind

2014-04-01

309

Behavior of a corium jet in high pressure melt ejection from a reactor pressure vessel.  

National Technical Information Service (NTIS)

This report provides results from analytical and experimental investigations on the behavior of a gas supersaturated molten jet expelled from a pressurized vessel. Aero-hydrodynamic stability of liquid jets in gas, stream degassing of molten metals and ga...

W. Frid

1987-01-01

310

Impinging jets atomization  

NASA Technical Reports Server (NTRS)

An analysis of the characteristics of the spray produced by an impinging-jet injector is presented. Predictions of the spray droplet size and distribution are obtained through studying the formation and disintegration of the liquid sheet formed by the impact of two cylindrical jets of the same diameter and momentum. Two breakup regimes of the sheet are considered depending on Weber number, with transition occurring at Weber numbers between 500 and 2000. In the lower Weber number regime, the breakup is due to Taylor cardioidal waves, while at Weber number higher than 2000, the sheet disintegration is by the growth of Kelvin-Helmholtz instability waves. Theoretical expressions to predict the sheet thickness and shape are derived for the low Weber number breakup regime. An existing mathematical analysis of Kelvin-Helmholtz instability of radially moving liquid sheets is adopted in the predictions of resultant drop sizes by sheet breakup at Weber numbers greater than 2000. Comparisons of present theoretical results with experimental measurements and empirical correlations reported in the literature reveal favorable agreement.

Ibrahim, E. A.; Przekwas, A. J.

1991-01-01

311

Marine Jet  

NASA Technical Reports Server (NTRS)

The marine turbine pump pictured is the Jacuzzi 12YJ, a jet propulsion system for pleasure or commercial boating. Its development was aided by a NASA computer program made available by the Computer Software Management and Information Center (COSMIC) at the University of Georgia. The manufacturer, Jacuzzi Brothers, Incorporated, Little Rock, Arkansas, used COSMIC'S Computer Program for Predicting Turbopump Inducer Loading, which enabled substantial savings in development time and money through reduction of repetitive testing.

1978-01-01

312

X-ray absorption spectrum for guanosine- 5'-monophosphate in water solution in the vicinity of the nitrogen K-edge observed in free liquid jet in vacuum  

NASA Astrophysics Data System (ADS)

A new spectroscopy for direct effect of radiation damage to nucleic acids such as DNA and RNA is underway using a liquid beam sample in vacuum combined with soft-X-ray synchrotron radiation. We show the X-ray absorption spectrum (XANES) of liquid phase water at X-ray photon energy in the vicinity of oxygen K-shell absorption edge obtained from total photoelectron yields ejected from a pure water beam. We confirm a "liquid sample in vacuum" for the present experiment by the measurements of the temperature dependence of the XANES spectrum for a liquid beam of pure water. Shown is the first measurement of the XANES spectrum for guanosine- 5'-monophosphate (GMP), which is one of the fundamental nucleotide unit for RNA, in water solution at X-ray photon energy in the vicinity of nitrogen K-shell absorption edge involved in the 'water-window' region, which corresponds to a selective excitation of guanine site.

Ukai, Masatoshi; Yokoya, Akinari; Fujii, Kentaro; Saitoh, Yuji

2008-10-01

313

Electrohydrodynamic (EHD) stimulation of jet breakup  

NASA Technical Reports Server (NTRS)

Electrohydrodynamic (EHD) excitation of liquid jets offers an alternative to piezoelectric excitation without the complex frequency response caused by piezoelectric and mechanical resonances. In an EHD exciter, an electrode near the nozzle applies an alternating Coulomb force to the jet surface, generating a disturbance which grows until a drop breaks off downstream. This interaction is modelled quite well by a linear, long wave model of the jet together with a cylindrical electric field. The breakup length, measured on a 33 micrometer jet, agrees quite well with that predicted by the theory, and increases with the square of the applied voltage, as expected. In addition, the frequency response is very smooth, with pronounced nulls occurring only at frequencies related to the time which the jet spends inside the exciter.

Crowley, J. M.

1982-01-01

314

Experimental study on flow kinematics and impact pressure in liquid sloshing  

NASA Astrophysics Data System (ADS)

This paper experimentally studied flow kinematics and impact pressure of a partially filled liquid sloshing flow produced by the periodic motion of a rectangular tank. The study focused on quantifying the flow velocities and impact pressures induced by the flow. Filled with water at a 30 % filling ratio, the tank oscillated at a resonant frequency and generated the violent sloshing flow. The flow propagated like breaking waves that plunged on both side walls and formed up-rushing jets that impacted on the top wall. Velocities of the multiphase flow were measured using the bubble image velocimetry technique. A total of 15 pressure sensors were mounted on the top wall and a side wall to measure the impact pressures. The local kinetic energy obtained by the measured local velocities was used to correlate with the corresponding pressures and determine the impact coefficient. In the sloshing flow, the flow direction was dominantly horizontal in the same direction of the tank motion before the wave crest broke and impinged on a side wall. At this stage, the maximum flow velocities reached 1.6 C with C being the wave phase speed. After the wave impingement, the uprising jet moved in the vertical direction with a maximum velocity reached 3.6 C before it impacted on the top wall. It was observed that the impact coefficients differed by almost one order of magnitude between the side wall impact and the top wall impact, mainly due to the large difference between the local velocities. A nearly constant impact coefficient was found for both side wall and top wall impacts if the impact pressures were directly correlated with the flow kinetic energy calculated using C instead of the local velocities.

Song, Youn Kyung; Chang, Kuang-An; Ryu, Yonguk; Kwon, Sun Hong

2013-09-01

315

Instabilities of a dense suspension jet  

NASA Astrophysics Data System (ADS)

We present experimental results on the behaviour of a dense suspension jet falling in a large volume of clear liquid. The jet is driven by gravity from a cylindrical reservoir full of a packed suspension. Different regimes are observed, depending on the Reynolds number of the jet, computed with the velocity of the suspension at the outlet of the reservoir. For viscous regimes, a striking feature is the formation of droplets of dense suspension which may be also unstable during their fall. For inertial regimes (large Reynolds number), dispersion of the particles occurs.

Nicolas, Maxime

2000-11-01

316

Spray formation processes of impinging jet injectors  

NASA Technical Reports Server (NTRS)

A study examining impinging liquid jets has been underway to determine physical mechanisms responsible for combustion instabilities in liquid bi-propellant rocket engines. Primary atomization has been identified as an important process. Measurements of atomization length, wave structure, and drop size and velocity distribution were made under various ambient conditions. Test parameters included geometric effects and flow effects. It was observed that pre-impingement jet conditions, specifically whether they were laminar or turbulent, had the major effect on primary atomization. Comparison of the measurements with results from a two dimensional linear aerodynamic stability model of a thinning, viscous sheet were made. Measured turbulent impinging jet characteristics were contrary to model predictions; the structure of waves generated near the point of jet impingement were dependent primarily on jet diameter and independent of jet velocity. It has been postulated that these impact waves are related to pressure and momentum fluctuations near the impingement region and control the eventual disintegration of the liquid sheet into ligaments. Examination of the temporal characteristics of primary atomization (ligament shedding frequency) strongly suggests that the periodic nature of primary atomization is a key process in combustion instability.

Anderson, W. E.; Ryan, H. M.; Pal, S.; Santoro, R. J.

1993-01-01

317

Numerical analysis of a plane problem concerning flow of a boiling liquid through Laval nozzles with subsequent expansion in a submerged jet  

Microsoft Academic Search

A solution is presented for the plane problem of flow of an evaporating liquid through Laval nozzles. In the subsonic and transonic parts of the Laval nozzle, the problem is solved using a finite difference scheme. The resulting parameter distributions for one of the cross sections of the supersonic flow are used as the initial data for solving a stationary

A. A. Makhmudov

1987-01-01

318

Growth of Convective and Absolute Instabilities in Co-flowing Jets  

Microsoft Academic Search

We have shown recently that the dripping-to-jetting transition in co-flowing liquids is controlled by two non-dimensional numbers: the capillary number (Caout) of the outer liquid and the Weber number of the inner liquid (Wein). When jetting is forced by Caout, the diameter of the jet narrows in the downstream direction and the drop size scaling is well predicted assuming that

Andrew Utada; Alberto Fernandez-Nieves; David Weitz

2007-01-01

319

Inclusive Jets in PHP  

NASA Astrophysics Data System (ADS)

Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, anti-k_T or SIScone jet algorithms. Cross sections are presented as functions of the jet pseudorapidity, eta(jet), and the jet transverse energy, E_T(jet). Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E_T(jet) and high eta(jet). The cross sections have the potential to improve the determination of the PDFs in future QCD fits. Values of alpha_s(M_Z) have been extracted from the measurements based on different jet algorithms. In addition, the energy-scale dependence of the strong coupling was determined.

Roloff, P.

320

Direct Liquid Cooling of High Flux Micro and Nano Electronic Components Boiling, evaporation, jet, and spray cooling, by suitable liquids such as fluorocarbons, might serve to control chip hot-spots and overheating  

Microsoft Academic Search

The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1k W\\/cm 2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical

Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

321

Simulations of dynamics of plunge and pitch of a three-dimensional flexible wing in a low Reynolds number flow  

NASA Astrophysics Data System (ADS)

The lattice Boltzmann flexible particle method (LBFPM) is used to simulate fluid-structure interaction and motion of a flexible wing in a three-dimensional space. In the method, a beam with rectangular cross section has been discretized into a chain of rigid segments. The segments are connected through ball and socket joints at their ends and may be bent and twisted. Deformation of flexible structure is treated with a linear elasticity model through bending and twisting. It is demonstrated that the flexible particle method (FPM) can approximate the nonlinear Euler-Bernoulli beam equation without resorting to a nonlinear elasticity model. Simulations of plunge and pitch of flexible wing at Reynolds number Re=136 are conducted in hovering condition by using the LBFPM. It is found that both lift and drag forces increase first, then decrease dramatically as the bending rigidity in spanwise direction decreases and that the lift and drag forces are sensitive to rigidity in a certain range. It is shown that the downwash flows induced by wing tip and trailing vortices in wake area are larger for a flexible wing than for a rigid wing, lead to a smaller effective angle of attack, and result in a larger lift force.

Qi, Dewei; Liu, Yingming; Shyy, Wei; Aono, Hikaru

2010-09-01

322

Transition from bubbling to jetting in a coaxial air-water jet  

NASA Astrophysics Data System (ADS)

In this Brief Communication we study experimentally the flow regimes that appear in coaxial air-water jets discharging into a stagnant air atmosphere and we propose a simple explanation for their occurrence based on linear, local, spatiotemporal stability theory. In addition to the existence of a periodic bubbling regime for low enough values of the water-to-air velocity ratio, u=uw/ua, our experiments revealed the presence of a jetting regime for velocity ratios higher than a critical one, uc. In the bubbling regime, bubbles form periodically from the tip of an air ligament whose length increases with u. However, when u>uc a long, slender gas jet is observed inside the core of the liquid coflow. Since in the jetting regime the downstream variation of the flow field is slow, we performed a local, linear spatiotemporal stability analysis with uniform velocity profiles to model the flow field of the air-water jet. Similar to the transition from dripping to jetting in capillary liquid jets, the analysis shows that the change from the bubbling to the jetting regime can be understood in terms of the transition from an absolute to a convective instability.

Sevilla, A.; Gordillo, J. M.; Martínez-Bazán, C.

2005-01-01

323

Physics of coal liquid slurry atomization. Final report to Department of Energy - PETC.  

National Technical Information Service (NTIS)

The stability of turbulent columns of liquid injected into a quiescent environment was studied. Laser Doppler Anemometry measurements of the flow patterns and turbulence characteristics in free liquid jets were made. Turbulence decay along Newtonian jets ...

N. Chigier A. Mansour

1995-01-01

324

Liquid Impact Erosion Mechanisms in Transparent Materials.  

National Technical Information Service (NTIS)

A study has been made of damage mechanisms caused by liquid drop impact on various infrared transparent solids. Techniques are described for producing liquid jets which simulate the damage produced by impact with spherical drops. Fracture damage to specim...

J. E. Field S. van der Zwaag J. T. Hagan

1981-01-01

325

A new ejector refrigeration system with an additional jet pump  

Microsoft Academic Search

A new ejector refrigeration system (NERS) with an additional liquid–vapor jet pump was proposed. The jet pump was used to decrease the backpressure of the ejector, and then the entrainment ratio and the coefficient of performance (COP) of the new system could be increased. The theoretical analysis and simulation calculation was carried out for the new system. The comparison between

Jianlin Yu; Hua Chen; Yunfeng Ren; Yanzhong Li

2006-01-01

326

Prevention of tissue damage by water jet during cavitation  

Microsoft Academic Search

Cavitation bubbles accompany explosive vaporization of water following pulsed energy deposition in liquid media. Bubbles collapsing at the tip of a surgical endoprobe produce a powerful and damaging water jet propagating forward in the axial direction of the probe. We studied interaction of such jet with tissue using fast flash photography and modeled the flow dynamics using a two-dimensional Rayleigh-type

Daniel Palanker; Alexander Vankov; Jason Miller; Menahem Friedman; Moshe Strauss

2003-01-01

327

Visualization of heat transfer from arrays of impinging jets  

NASA Astrophysics Data System (ADS)

A visualization technique is used to measure the heat transfer coefficient distribution on a flat plate on which either a single jet or an array of jets impinges. Liquid crystals coated on a mylar sheet are used to locate isotherms on a heated surface. By adjusting the surface heat flux, contours of constant heat transfer coefficient are obtained.

Goldstein, R. J.; Timmers, J. F.

1982-12-01

328

Slender jets and thin sheets with surface tension  

Microsoft Academic Search

Simplified equations governing the potential flow and the shape of slender jets and thin sheets of liquid are derived, taking into account surface tension. Families of similarity solutions of these equations are introduced. For jets and for symmetrical sheets they satisfy ordinary differential equations. The properties of these similarity solutions are examined analytically and numerically. They can be used to

Ting Lu; Joseph B. Keller

1990-01-01

329

Constraints on JP-900 Jet Fuel Production Concepts.  

National Technical Information Service (NTIS)

Researchers at the Energy Institute of Pennsylvania State University (Penn State) are conducting research on producing jet fuel by coprocessing coal or coal-derived products with low-value liquid intermediates produced during petroleum refining. To date, ...

J. T. Bartis G. T. Flint

2007-01-01

330

[Development of a novel liquid injection system].  

PubMed

A liquid jet injector employs compressed gas or spring to produce a high-velocity stream to deliver liquid drug into human body through skin. There are many clinical jet injection products available, none of which is domestic. A new liquid jet injector is designed based on a comprehensive analysis of the current products. The injector consists of an ejector, trigger and a re-positioning mechanism. The jets characteristics of sample injector are tested, and the results show that the maximum exit pressure is above 15 MPa, a threshold value for penetrating into the skin. PMID:20352911

Chen, Kai; Lv, Yong-Gui

2009-11-01

331

Viscoelastic effects on the jetting-dripping transition in co-flowing capillary jets  

Microsoft Academic Search

Linear hydrodynamics stability analysis is used to determine the influence of elasticity on the jetting-dripping transition and on the temporal stability of non-axisymmetric modes in co-flowing capillary jets. The critical Weber number for which axisymmetric perturbations undergo a transition from convective to absolute instability is calculated from the spatio-temporal analysis of the dispersion relation for Oldroyd-B liquids, as a function

Jose M. Montanero; Alfonso M. Ganan-Calvo

2008-01-01

332

Viscoelastic effects on the jetting?dripping transition in co-flowing capillary jets  

Microsoft Academic Search

Linear hydrodynamics stability analysis is used to determine the influence of elasticity on the jetting-dripping transition and on the temporal stability of non-axisymmetric modes in co-flowing capillary jets. The critical Weber number for which axisymmetric perturbations undergo a transition from convective to absolute instability is calculated from the spatio-temporal analysis of the dispersion relation for Oldroyd-B liquids, as a function

J. M. Montanero

2008-01-01

333

HOT-SPOT REMEDIATION USING IN-SITU JETTING TECHNOLOGY  

Microsoft Academic Search

Jetting technology using high-pressure, low to high volume injection of liquids into the subsurface using a small-diameter wand or lance driven into the subsurface has been widely used for several decades. Jetting technology, at its most basic, uses tree root feeder systems to inject liquids into the ground. The Remediation Injection Process (RlP ®), an updated and more powerful, versatile

James A. Jacobs

334

General review of flashing jet studies.  

PubMed

The major concern on the management of superheated liquids, in industrial environments, is the large potential hazards involved in cases of any accidental release. There is a possibility that a violent phase change could take place inside the fluid released generating a flashing jet. This violent phase change might produce catastrophic consequences, such as explosions, fires or toxic exposure, in the installations and in the surroundings. The knowledge and understanding of the mechanisms involved in those releases become an important issue in the prevention of these consequences and the minimization of their impact. This work presents a comprehensive review of information about flashing processes. The review begins with a description of the single phase jet followed by a description of the two-phase flashing jet. The concepts and implications of the thermodynamic and mechanical effects on the behaviour of the jets are considered at the beginning of the review. Following the review is devoted to the classification of the different study approaches used to understand flashing processes in the past, highlighting various critical parameters on the behaviour and the hazard consequences of flashing jets. The review also contains an extensive compilation of experimental, theoretical and numerical data relating to these phenomena, which includes information on the distinct characteristics of the jet, since type of jet, velocity distribution, expansion angle and mass phase change all require individual estimation. PMID:19846254

Polanco, Geanette; Holdø, Arne Erik; Munday, George

2010-01-15

335

Jet fuels from synthetic crudes  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the technical problems in the conversion of a significant portion of a barrel of either a shale oil or a coal synthetic crude oil into a suitable aviation turbine fuel. Three syncrudes were used, one from shale and two from coal, chosen as representative of typical crudes from future commercial production. The material was used to produce jet fuels of varying specifications by distillation, hydrotreating, and hydrocracking. Attention is given to process requirements, hydrotreating process conditions, the methods used to analyze the final products, the conditions for shale oil processing, and the coal liquid processing conditions. The results of the investigation show that jet fuels of defined specifications can be made from oil shale and coal syncrudes using readily available commercial processes.

Antoine, A. C.; Gallagher, J. P.

1977-01-01

336

Pulse Jet Mixing Tests With Noncohesive Solids  

Microsoft Academic Search

This report summarizes results from pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid conducted during FY 2007 and 2008 to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant (WTP). Tests were conducted at three geometric scales using noncohesive simulants. The test data were used to independently develop mixing models that can

Perry A. Meyer; Judith A. Bamberger; Carl W. Enderlin; James A. Fort; Beric E. Wells; S. K. Sundaram; Paul A. Scott; Michael J. Minette; Gary L. Smith; Carolyn A. Burns; Margaret S. Greenwood; Gerald P. Morgen; Ellen BK Baer; Sandra F. Snyder; Michael White; Gregory F. Piepel; Brett G. Amidan; Alejandro Heredia-Langner; Sharon A. Bailey; John C. Bower; Kayte M. Denslow; David E. Eakin; Monte R. Elmore; Phillip A. Gauglitz; Anthony D. Guzman; Brian K. Hatchell; Derek F. Hopkins; David E. Hurley; Michael D. Johnson; Leslie J. Kirihara; Bruce D. Lawler; Jesse S. Loveland; O Dennis Mullen; Mikhail S. Pekour; Timothy J. Peters; Peter J. Robinson; Michael S. Russcher; Susan Sande; Christian Santoso; Steven V. Shoemaker; Steve M. Silva; Devin E. Smith; Yin-Fong Su; James J. Toth; John D. Wiberg; Xiao-Ying Yu; Nino Zuljevic

2009-01-01

337

30 CFR Jet - Surface Only  

Code of Federal Regulations, 2010 CFR

...false Surface Only Jet Rotary Jet Piercing Mineral Resources MINE SAFETY AND...NONMETAL MINES Drilling and Rotary Jet Piercing Drilling-Surface and Underground...46517, Sept. 12, 1991] Rotary Jet PiercingâSurface...

2010-07-01

338

Taking the Plunge.  

ERIC Educational Resources Information Center

Describes why lake hikes practiced at Girl Scout Camp Bonnie Brae (Massachusetts) are an ideal camp activity to teach aquatic ecology and engage the senses. Discusses program benefits: camper/counselor interaction, personal and group challenge, and conflict resolution. (NEC)

Hatch, Stanley

1987-01-01

339

Thermal visualization of heat-transfer characteristics for single impinging jet  

NASA Astrophysics Data System (ADS)

The local heat-transfer characteristics of an impingement-cooling jet are presently ascertained, for cases with and without crossflow, through the use of a combined metal heating-element and cholesteric liquid crystal system. The results obtained indicate that the impingement Nusselt numbers of double-peak values increase with rising jet Reynolds number. A moving cylindrical jet-source model is used to simulate and analyze the jet's impingement heat transfer.

Li, Liguo; Zhu, Yun; Zhang, Jingzhou; Yu, Wei

340

Jet Wave Hemodialyzer.  

National Technical Information Service (NTIS)

The results of a program to study jet wave hemodialysis, and in particular to determine mass transfer characteristics of the method, are presented. An experimental model of a rotating jet hemodialyzer was constructed and tested. The dialyzer included rota...

A. J. Sipin D. Snyder

1970-01-01

341

High-speed jetting and spray formation from bubble collapse  

NASA Astrophysics Data System (ADS)

A method to create impacting jets at the micrometer length scale by means of a collapsing cavitation bubble is presented. A focused shock wave from a lithotripter leads to the nucleation of a cavitation bubble below a hole of 25 ?m diameter etched in a silicon plate. The plate is placed at an air-water interface. The expansion and collapse of the bubble leads to two separate jets—an initial slow jet of velocity ˜10 m/s and a later faster jet of velocity ˜50 m/s. The jets subsequently impact coaxially, resulting in a circular sheet of liquid in the plane perpendicular to their axis. The sheet is characterized by a ring of droplets at its rim and breaks up into a spray as the shock pressure is increased. The results demonstrate an approach to create a high-speed jet and fine spray on demand at the micrometer scale.

Karri, Badarinath; Avila, Silvestre Roberto Gonzalez; Loke, Yee Chong; O'Shea, Sean J.; Klaseboer, Evert; Khoo, Boo Cheong; Ohl, Claus-Dieter

2012-01-01

342

Water jet symposium  

Microsoft Academic Search

A symposium is presented dealing with the theoretical and experimental aspects of high pressure water jet cutting technology and its application to mining and civil engineering, as well as for industrial use. The application of water jets is diversified. The mining industry is already using water jets for development and production drilling in uranium, and is working on applying borehole

F. D. Wang; L. Ozdemir; R. Miller

1982-01-01

343

Jet shapes at Hera  

SciTech Connect

The shape of jets produced in quasi-real photon-proton interactions and deep inelastic positron-proton scattering (DIS) at high Q{sup 2} (Q{sup 2}>100 GeV{sup 2}) has been measured with the ZEUS detector at HERA. Jets with transverse energies E{sub T}{sup jet}>14 GeV and pseudorapidities ({eta}{sup jet}) in the range -1<{eta}{sup jet}<2 are searched for using a cone algorithm in the ep-laboratory frame in the {eta}-{phi} plane with a cone radius of one unit. The jet shape broadens as {eta}{sup jet} increases and narrows as E{sub T}{sup jet} increases. Next-to-leading order QCD calculations for inclusive jet photoproduction provide predictions for the jet shapes at the parton level which are found to be consistent with the measurements. The measured jet shapes in neutral current DIS are compared to those in photon-proton collisions and are found to be narrower. The measured jet shapes in DIS are found to be narrower than those in pp-bar collisions, and are similar to those in e{sup +}e{sup -} interactions.

Martinez, Mario [Departamento de Fisica Teorica, Universidad Autonoma de Madrid, Ciudad Universitaria Cantoblanco, Madrid (Spain)

1997-04-20

344

Theoretical and experimental study on underwater jet characteristics from a submerged combustion system  

NASA Astrophysics Data System (ADS)

In this paper, an exhaust noise underwater is investigated experimentally and theoretically. The effects of high temperature and gas-water two-phase on underwater jet noise are analyzed. Results show that, higher exhaust gas temperatures generate louder jet noise underwater, including radiated noise from the tube orifice and bubble noise after detachment from orifice. But gas temperature has little effect on air-air jet noise. Another conclusion from experimental results is that injecting water into air-air jet system can effectively reduce jet noise but has less effect on air-water jet system. Turbulent dynamic noise, generated by air-air interaction, is the main noise source for air-air jet, but turbulent dynamic noise can be ignored in air-water jet considering gas-liquid density difference.And water droplet injected into air reduces the turbulent kinetic energy of the gas, therefor reduces the turbulent dynamic noise in air-air jet system.

Lu, R.; Qin, X. H.; Wu, D. Z.; Wang, H. W.

2013-12-01

345

Coaxial atomizer liquid intact lengths  

NASA Technical Reports Server (NTRS)

Average intact lengths of round liquid jets generated by airblast coaxial atomizer were measured from over 1500 photographs. The intact lengths were studied over a jet Reynolds number range of 18,000 and Weber number range of 260. Results are presented for two different nozzle geometries. The intact lengths were found to be strongly dependent on Re and We numbers. An empirical equation was derived as a function of these parameters. A comparison of the intact lengths for round jets and flat sheets shows that round jets generate shorter intact lengths.

Eroglu, Hasan; Chigier, Norman; Farago, Zoltan

1991-01-01

346

Jets at CDF  

SciTech Connect

Recent jet results in p{bar p} collisions at {radical}s = 1.96 TeV from the CDF experiment at the Tevatron are presented. The jet inclusive cross section is compared to next-to-leading order QCD prediction in different rapidity regions. The b-jet inclusive cross section is measured exploiting the long lifetime and large mass of B-hadrons. Jet shapes, W+jets and W/Z+photon cross sections are also measured and compared to expectations from QCD production.

Gallinaro, Michele; /Rockefeller U.

2006-08-01

347

Fluid jet electric discharge source  

DOEpatents

A fluid jet or filament source and a pair of coaxial high voltage electrodes, in combination, comprise an electrical discharge system to produce radiation and, in particular, EUV radiation. The fluid jet source is composed of at least two serially connected reservoirs, a first reservoir into which a fluid, that can be either a liquid or a gas, can be fed at some pressure higher than atmospheric and a second reservoir maintained at a lower pressure than the first. The fluid is allowed to expand through an aperture into a high vacuum region between a pair of coaxial electrodes. This second expansion produces a narrow well-directed fluid jet whose size is dependent on the size and configuration of the apertures and the pressure used in the reservoir. At some time during the flow of the fluid filament, a high voltage pulse is applied to the electrodes to excite the fluid to form a plasma which provides the desired radiation; the wavelength of the radiation being determined by the composition of the fluid.

Bender, Howard A. (Ripon, CA) [Ripon, CA

2006-04-25

348

LASER PLASMA AND LASER APPLICATIONS: Spatial and temporal distributions of liquid drops in an erosion jet formed as a result of interaction of laser radiation with a lead target  

NASA Astrophysics Data System (ADS)

A determination was made of the spatial and temporal distributions of the transmission, scattering, and absorption coefficients of ruby laser radiation used to probe an erosion jet created as a result of interaction of radiation from a free-running neodymium laser (output energy ~ 1 kJ and pulse duration ~ 1 ms) with a lead target. The experiments with a probe beam were supplemented by a spectroscopic study of the erosion jet. The probe results and the Love-Mie scattering theory were used to determine the spatial and temporal distribution of lead drops in an erosion jet formed as a result of volume vaporization.

Goncharov, V. K.; Karaban', V. I.; Kolesnik, A. V.; Radyuk, I. M.

1988-12-01

349

Jet Substructure Without Trees  

SciTech Connect

We present an alternative approach to identifying and characterizing jet substructure. An angular correlation function is introduced that can be used to extract angular and mass scales within a jet without reference to a clustering algorithm. This procedure gives rise to a number of useful jet observables. As an application, we construct a top quark tagging algorithm that is competitive with existing methods. In preparation for the LHC, the past several years have seen extensive work on various aspects of collider searches. With the excellent resolution of the ATLAS and CMS detectors as a catalyst, one area that has undergone significant development is jet substructure physics. The use of jet substructure techniques, which probe the fine-grained details of how energy is distributed in jets, has two broad goals. First, measuring more than just the bulk properties of jets allows for additional probes of QCD. For example, jet substructure measurements can be compared against precision perturbative QCD calculations or used to tune Monte Carlo event generators. Second, jet substructure allows for additional handles in event discrimination. These handles could play an important role at the LHC in discriminating between signal and background events in a wide variety of particle searches. For example, Monte Carlo studies indicate that jet substructure techniques allow for efficient reconstruction of boosted heavy objects such as the W{sup {+-}} and Z{sup 0} gauge bosons, the top quark, and the Higgs boson.

Jankowiak, Martin; Larkoski, Andrew J.; /SLAC /Stanford U., ITP

2011-08-19

350

Enhancement of single-phase heat transfer and critical heat flux from an ultra-high-flux simulated microelectronic heat source to a rectangular impinging jet of dielectric liquid  

Microsoft Academic Search

Jet impingement is encountered in numerous applications demanding high heating or cooling fluxes. Examples include annealing of metal sheets and cooling of turbine blades, x-ray medical devices, laser weapons, and fusion blankets. The attractive heat transfer attributes of jet impingement have also stimulated research efforts on cooling of high-heat-flux microelectronic devices. These devices are fast approaching heat fluxes in excess

D. C. Wadsworth; I. Mudawar

1992-01-01

351

Jet pump assisted arterial heat pipe  

NASA Technical Reports Server (NTRS)

This paper discusses the concept of an arterial heat pipe with a capillary driven jet pump. The jet pump generates a suction which pumps vapor and noncondensible gas from the artery. The suction also forces liquid into the artery and maintains it in a primed condition. A theoretical model was developed which predicts the existence of two stable ranges. Up to a certain tilt the artery will prime by itself once a heat load is applied to the heat pipe. At higher tilts, the jet pump can maintain the artery in a primed condition but self-priming is not possible. A prototype heat pipe was tested which self-primed up to a tilt of 1.9 cm, with a heat load of 500 watts. The heat pipe continued to prime reliably when operated as a VCHP, i.e., after a large amount of noncondensible gas was introduced.

Bienert, W. B.; Ducao, A. S.; Trimmer, D. S.

1978-01-01

352

Jet Propagation and Deceleration  

NASA Astrophysics Data System (ADS)

Extragalactic jets in active galactic nuclei (AGN) are divided into two morphological types, namely Fanaroff-Riley I (FRI) and Fanaroff-Riley II (FRII). The former show decollimated structure at the kiloparsec scales and are thought to be decelerated by entrainment within the first kiloparsecs of evolution inside the host galaxy. The entrainment and deceleration can be, at least partly, due to the interaction of jets with stellar winds and gas clouds that enter in the jet as they orbit around the galactic centre. In this contribution, I review recent simulations to study the dynamic effect of entrainment from stellar winds in jets and the direct interaction of jets with gas clouds and stellar winds. I also briefly describe the importance of these interactions as a possible scenario of high-energy emission from extragalactic jets.

Perucho, Manel

2014-03-01

353

Mathematical modeling of a gas jet impinging on a two phase bath  

NASA Astrophysics Data System (ADS)

In this work a three phase 3D mathematical model was developed using the Volume Of Fluid (VOF) algorithm, which is able to accurately describe the cavity geometry and size as well as the liquid flow patterns created when a gas jet impinges on a two phase liquid free surface. These phenomena are commonly found in steelmaking operations such as in the Electric Arc Furnace (EAF) and the Basic Oxygen Furnace (BOF) where oxygen jets impinge on a steel bath and they control heat, momentum and mass transfer. The cavity formed in the liquids by the impinging jet depends on a force balance at the free surface where the inertial force of the jet governs these phenomena. The inertial force of the jet and its angle play important roles, being the lowest angle the best choice to shear the bath and promote stronger circulation and better mixing in the liquids.

Delgado-Álvárez, J.; Ramírez-Argáez, Marco A.; González-Rivera, C.

2012-09-01

354

Refrigerated hydrogen gas jet for the Fermilab antiproton accumulator  

SciTech Connect

A hydrogen gas jet has been built for use at Fermilab for the study of charmonium spectroscopy in proton-antiproton annihilations. The hydrogen gas jet is part of an upgrade to a previous experiment which ran in the Fermilab 1990-1991 fixed target program utilizing a jet cooled to 80 K with liquid nitrogen. The jet delivers a defined stream of hydrogen gas which travels through a series of vacuum chambers and then intersects the circulating antiproton beam. The goal of the upgrade is to provide a hydrogen gas stream at least twice as dense as used for the earlier experiment to increase the interaction rate and allow an improved study of rare processes. This is achieved by cooling the stream to below 30 K using a Gifford-McMahon refrigerator. The jet apparatus is designed to allow motion in the plane perpendicular to the gas stream as well as angular positioning at the jet nozzle to provide a means of optimizing the interaction rate. Two skimmers located in the vacuum chambers are used to define the gas stream dimensions. The jet target vacuum chambers require constant pumping with turbomolecular pumps. The vacuum space around the jet is designed to have a large system pumping speed so that the chamber pressure can be maintained below an absolute pressure of 1 Pa. The jet will operate in the next fixed target run at Fermilab. Details of the design and test results are discussed.

Allspach, D.H.; Kendziora, C.L. [Fermi National Accelerator Lab., Batavia, IL (United States); Marinelli, M. [Univ. of Genoa (Italy). Dept. of Physics] [and others

1995-07-01

355

Hotspots, Jets and Environments  

NASA Astrophysics Data System (ADS)

I discuss the nature of `hotspots' and `jet knots' in the kpc-scale structures of powerful radio galaxies and their relationship to jet-environment interactions. I describe evidence for interaction between the jets of FRI sources and their local environments, and discuss its relationship to particle acceleration, but the main focus of the paper is the hotspots of FRIIs and on new observational evidence on the nature of the particle acceleration associated with them.

Hardcastle, M. J.

2008-06-01

356

Contact Angle Influence on Geysering Jets in Microgravity Investigated  

NASA Technical Reports Server (NTRS)

Microgravity poses many challenges to the designer of spacecraft tanks. Chief among these are the lack of phase separation and the need to supply vapor-free liquid or liquid-free vapor to the spacecraft processes that require fluid. One of the principal problems of phase separation is the creation of liquid jets. A jet can be created by liquid filling, settling of the fluid to one end of the tank, or even closing a valve to stop the liquid flow. Anyone who has seen a fountain knows that jets occur in normal gravity also. However, in normal gravity, the gravity controls and restricts the jet flow. In microgravity, with gravity largely absent, surface tension forces must be used to contain jets. To model this phenomenon, a numerical method that tracks the fluid motion and the surface tension forces is required. Jacqmin has developed a phase model that converts the discrete surface tension force into a barrier function that peaks at the free surface and decays rapidly away. Previous attempts at this formulation were criticized for smearing the interface. This can be overcome by sharpening the phase function, double gridding the fluid function, and using a higher-order solution for the fluid function. The solution of this equation can be rewritten as two coupled Poisson equations that also include the velocity.

Chato, David J.

2004-01-01

357

Properties of gluon jets  

SciTech Connect

The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed.

Sugano, K.

1986-09-01

358

Stability of Astrophysical Jets  

NASA Astrophysics Data System (ADS)

Compared to their terrestrial and laboratory counterparts, the astrophysical jets appear to be very stable - for example, the extragalactic jets cross the distances that are up to one billion times larger than their initial radius. Many years after their discovery and numerous theoretical and numerical studies, there is still no consensus as to what is behind this remarkable stability. We argue that this must be a very robust reason, not sensitive to the details of internal jet structure and composition, but rather reflecting their environment. In particular, the astrophysical jets propagate through "atmospheres" with rapidly declining pressure (and density), which results in their rapid sideways expansion - e.g. the radius of the M87 jet increases by the factor close to one million. Such a rapid expansion renders the causal connectivity across jets ineffective and can even suppress it altogether, resulting infree expansion of the jets. When the connectivity is lacking, the jets cannot develop coherent large scale displacements, which otherwise would threaten their integrity and survival. We present the results of new 3D numerical simulations of expanding magnetized relativistic jets, designed to test this idea.

Komissarov, Serguei

2014-08-01

359

Jetting instability mechanisms of particles from explosive dispersal  

NASA Astrophysics Data System (ADS)

The formation of post-detonation 'particle' jets is widely observed in many problems associated with explosive dispersal of granular materials and liquids. Jets have been shown to form very early, however the mechanism controlling the number of jetting instabilities remains unresolved despite a number of active theories. Recent experiments involving cylindrical charges with a range of central explosive masses for dispersal of dry solid particles and pure liquid are used to formulate macroscopic numerical models for jet formation and growth. The number of jets is strongly related to the dominant perturbation during the shock interaction timescale that controls the initial fracturing of the particle bed and liquid bulk. Perturbations may originate at the interfaces between explosive, shock-dispersed media, and outer edge of the charge due to Richtmyer-Meshkov instabilities. The inner boundary controls the number of major structures, while the outer boundary may introduce additional overlapping structures and microjets that are overtaken by the major structures. In practice, each interface may feature a thin casing material that breaks up, thereby influencing or possibly dominating the instabilities. Hydrocode simulation is used to examine the role of each interface in conjunction with casing effects on the perturbation leading to jet initiation. The subsequent formation of coherent jet structures requires dense multiphase flow of particles and droplets that interact though inelastic collision, agglomeration, and turbulent flow. Macroscopic multiphase flow simulation shows dense particle clustering and major jet structures overtaking smaller instabilities. Late-time dispersal is controlled by particle drag and evaporation of droplets. Numerical results for dispersal and jetting evolution are compared with experiments.

Ripley, R. C.; Zhang, F.

2014-05-01

360

Environmental monitoring for tritium at jet  

SciTech Connect

JET progressively established elements of an environmental monitoring programme well in advance of tritium operation in order to determine baseline levels. Prior to the first JET tritium experiment (PTE) in 1991, an extensive programme was in place and agreed with the regulatory authority. This consisted of tritium in air, rain, ground and river water, and crops on and off the JET site. Air is sampled continuously and averaged monthly. Other samples are taken quarterly or, at an appropriate point in the growing season. The discharges of tritium from the JET stacks are monitored by on-line instrumentation and silica gel-based samplers. The performance of these is described and improvements arising from the PTE experience are discussed. In particular the implications of tritiated methane on sampling and analysis are considered. The results of environmental monitoring are presented and comparisons made with predictions from discharges made during the PTE and subsequent operations. The implications of washout on the site liquid discharge authorization is considered. From a comparison of observed and predicted concentrations, routine releases of tritium from JET will have insignificant environmental impact. 8 refs., 11 figs., 2 tabs.

Bell, A.C.; Caldwell-Nichols, C.; Patel, B.; Serio, L. [JET Joint Undertaking, Abingdon (United Kingdom)

1995-10-01

361

Tritium retention in jet cryopanel samples  

SciTech Connect

The possibility that tritium might exchange with water trapped in aluminum anodize cryopanels in JET prompted a test program at the Tritium Systems Test Assembly, TSTA, Los Alamos, New Mexico. JET furnished two test pieces of cryopanel which were exposed to tritium at approximately liquid nitrogen temperature and 25 torr pressure for nearly two weeks. One specimen was removed and the retained tritium was measured. The second specimen was subjected to several increasing temperature vacuum bakeouts and the effectiveness of the bakeouts were inferred from the pressure history of the chamber. When the retained tritium in the second specimen was measured it was found that nearly 95% of the tritium, as measured in the first specimen, had been removed during the vacuum bakeouts. If the tritium retained in the cryopanel without bakeout were scaled to JET conditions according to a linear pressure time relationship, the tritium expected to become trapped in the JET cryopanels would be approximately 0.6 gram. Testing is currently underway at TSTA which will determine the tritium retention to be expected under more realistic JET operating conditions and which will assess the effectiveness of various bake or purge schemes in removing the trapped tritium. 2 refs., 2 figs.

Walthers, C.R.; Jenkins, E.M. (Los Alamos National Lab., NM (United States)); Mayaux, C.; Obert, W. (JET Joint Undertaking, Oxfordshire, England (GB))

1991-01-01

362

Concentration Distributions during Pulse Jet Mixing  

SciTech Connect

Obtaining real-time, in situ slurry concentration measurements during unsteady mixing can provide increased understanding into mixer performance. During recent tests an ultrasonic attenuation sensor was inserted into a mixing vessel to measure the slurry concentration during unsteady mixing in real time during pulse jet mixer operation. These pulse jet mixing tests to suspend noncohesive solids in Newtonian liquid were conducted at three geometric scales. To understand the solids suspension process and resulting solids distribution, the concentration of solids in the cloud was measured at various elevations and radial positions during the pulse jet mixer cycle. In the largest scale vessel, concentration profiles were measured at three radial locations: r = 0, 0.5 and 0.9 R where R is the vessel radius. These radial concentration data are being analyzed to provide a model for predicting concentration as a function of elevation. This paper describes pulse jet mixer operation, provides a description of the concentration probe, and presents transient concentration data obtained at three radial positions: in the vessel center (O R), midway between the center and the wall (0.5 R) and near the vessel wall (0.9 R) through out the pulse to provide insight into pulse jet mixer performance.

Bamberger, Judith A.; Meyer, Perry A.

2010-08-05

363

Experimental study on simulated molten jet-coolant interactions  

Microsoft Academic Search

Molten fuel-coolant interactions in a jet contact mode was studied with respect to the safety of liquid-metal-cooled fast breeder reactors (LMFBRs). From a series of molten Wood's metal (melting point 79 °C) jet-water interaction experiments, several distinct modes of interaction behaviors were observed for various combinations of initial temperature conditions of the two fluids. A semi-empirical model for a minimum

Sa. Kondo; K. Konishi; M. Isozaki; S. Imahori; A. Furutani; D. J. Brear

1995-01-01

364

Calibrated single-plunge bipolar electrode array for mapping myocardial vector fields in three dimensions during high-voltage transthoracic defibrillation.  

PubMed

Mapping of the myocardial scalar electric potential during defibrillation is normally performed with unipolar electrodes connected to voltage dividers and a global potential reference. Unfortunately, vector potential gradients that are calculated from these data tend to exhibit a high sensitivity to measurement errors. This paper presents a calibrated single-plunge bipolar electrode array (EA) that avoids the error sensitivity of unipolar electrodes. The EA is triaxial, uses a local potential reference, and simultaneously measures all three components of the myocardial electric field vector. An electrode spacing of approximately 500 microm allows the EA to be direct-coupled to high-input-impedance, isolated, differential amplifiers and eliminates the need for voltage dividers. Calibration is performed with an electrolytic tank in which an accurately measured, uniform electric field is produced. For each EA, unique calibration matrices are determined which transform potential difference readings from the EA to orthogonal components of the electric field vector. Elements of the matrices are evaluated by least squares multiple regression analysis of data recorded during rotation of the electric field. The design of the electrolytic tank and electrode holder allows the electric field vector to be rotated globally with respect to the electrode axes. The calibration technique corrects for both field perturbation by the plunge electrode body and deviations from orthogonality of the electrode axes. A unique feature of this technique is that it eliminates the need for mechanical measurement of the electrode spacing. During calibration, only angular settings and voltages are recorded. For this study, ten EAs were calibrated and their root-mean-square (rms) errors evaluated. The mean of the vector magnitude rms errors over the set of ten EAs was 0.40% and the standard deviation 0.07%. Calibrated EAs were also tested for multisite mapping in four dogs during high-voltage transthoracic shocks. PMID:11499527

Deale, O C; Ng, K T; Kim-Van Housen, E J; Lerman, B B

2001-08-01

365

Fake plunges are very eccentric real EMRIs in disguise. …they dominate the rates and are blissfully ignorant of angular momentum barriers  

NASA Astrophysics Data System (ADS)

The capture of a compact object in a galactic nucleus by a massive black hole (MBH) is the best way to map space and time around it. Compact objects such as stellar black holes on a capture orbit with a very high eccentricity have been wrongly assumed to be lost for the system after an intense burst of radiation, which has been described as a "direct plunge". We prove that these very eccentric capture orbits spend actually a similar number of cycles in a LISA-like detector as those with lower eccentricities if the central MBH is spinning. Although the rates are higher for high-eccentricity EMRIs, the spin also enhances the rates of lower-eccentricity EMRIs. This last kind have received more attention because of the fact that high-eccentricity EMRIs were thought to be direct plunges and thus negligible. On the other hand, recent work on stellar dynamics has demonstrated that there seems to be a complot in phase space acting on these lower-eccentricity captures, since their rates decrease significantly by the presence of a blockade in the rate at which orbital angular momenta change takes place. This so-called "Schwarzschild barrier" is a result of the impact of relativistic precession on to the stellar potential torques, and thus it affects the enhancement on lower-eccentricity EMRIs that one would expect from resonant relaxation. We confirm and quantify the existence of this barrier using a statitical sample of 2,500 direct-summation N-body simulations using both a post-Newtonian but also, and for the first time, a geodesic approximation for thse relativistic orbits. The existence of the barrier prevents "traditional EMRIs" from approaching the central MBH, but if the central MBH is spinning the rate will be anyway dominated by highly-eccentric extreme-mass ratio inspirals, which insolently ignore the presence of the barrier, because they are driven by two-body relaxation.

Amaro-Seoane, P.; Sopuerta, C. F.; Brem, P.

2012-12-01

366

Simple and Double Emulsions via Coaxial Jet Electrosprays  

NASA Astrophysics Data System (ADS)

We report for the first time the generation of electrified coaxial jets of micrometric diameter in liquid media. Scaling laws to predict the inner and outer diameter of the coaxial jet are given. We show some experiments illustrating the formation process of the coaxial jet, and demonstrate how this process can be used to yield either o/w (oil in water) or o/w/o (oil/water/oil) emulsions of micrometric size. Some interesting analogies with other hydrodynamic focusing processes are also pointed out.

Marín, Álvaro G.; Loscertales, Ignacio G.; Márquez, M.; Barrero, A.

2007-01-01

367

Jet Streak Circulations  

NSDL National Science Digital Library

This Webcast is based on a presentation given by Dr. James T. Moore of Saint Louis University at the 5th Annual MSC/COMET Winter Weather Workshop on 30 November 2004 in Boulder, Colorado. Dr. Moore reviews many aspects of jet streak dynamics including convergence/divergence, ageostrophic winds, propagation, and coupled jets.

Spangler, Tim

2005-04-25

368

JET ENGINE CERTIFICATION STANDARDS  

Microsoft Academic Search

The ability of modern jet engines to ingest birds and continue to operate is largely misunderstood or not contemplated at all in the aviation industry. Currently, there is not one jet engine operating in the world that is certified to ingest one large bird (goose, swan, stork, pelican, vulture, etc) and continue to operate. The effort to harmonize bird ingestion

Paul Eschenfelder

2000-01-01

369

Plasma heating in JET  

Microsoft Academic Search

Heating the JET plasma well above temperatures reached in the ohmic phase is the aim of the two additional heating systems planned for JET: ion cyclotron resonance heating (ICRF) and neutral beam injection (NBI). Operations with the latter started in February 1986, initially with hydrogen injection, up to a power level of 7 MW. ICRF power has been delivered to

A. Ainsworth; H. Altmann; R. J. Anderson; J. Arbez; D. Bartlett; W. Bailey; K. Behringer; E. Bertolini; P. Bertoldi; C. H. Best; V. Bhatnagar; R. J. Bickerton; G. Boissin; T. Bonicelli; S. Booth; A. Boschi; G. Bosia; M. Botman; H. Brelen; H. Brinkschulte; M. L. Browne; M. Brusati; T. Budd; M. Bures; P. Butcher; H. Buttgereit; D. Cacaut; C. Caldwell-Nichols; D. Campbell; J. Carwardine; G. Celentano; C. D. Challis; A. Cheetman; J. Christiansen; C. Christodoulopoulos; P. Chuilon; R. Claesen; J. P. Coad; M. Cooke; J. G. Cordey; W. Core; S. Corti; A. E. Costley; G. Cottrell; J. Dean; E. Deksnis; G. Deschamps; K. J. Dietz; J. Dobbing; S. E. Dorling; D. F. Duechs; G. Duesing; H. Duquenoy; L. de Kock; A. Edwards; W. Engelhardt; F. Erhorn; B. Eriksson; H. Falter; T. Hellsten; J. L. Hemmerich; R. Hemsworth; F. Hendriks; R. F. Herzog; L. Horton; J. How; M. Huart; A. Hubbard; M. Hugon; P. Jones; J. Kaeline; A. Kaellne; A. Kaye; B. E. Keen; M. Keilhacker; G. Kinahan; A. Konstantellos; P. Kupschus; P. Lallia; J. R. Last; N. Foden; C. Froger; K. Fullard; A. Galetsas; A. Gallacher; A. Gibson; R. D. Gill; A. Geode; A. Gondhalekar; N. A. Gottardi; C. Gowers; R. Granetz; B. Green; S. Gregoli; F. S. Griph; R. Haange; C. J. Hancock; P. Harbour; R. F. Herog; J. Kaellne; L. Lauro-Taroni; E. Lazzaro; R. C. Lobel; P. Lomas; M. Lorenzo-Gottardi; C. Lowry; G. Magyar; D. Maissonneir; M. Malacarne; V. Marchese; P. Massmann; P. McMullen; M. J. Mead; P. Meriguet; V. Merlo; S. Mills; P. Millward; A. Moissonnier; P. L. Mondini; P. Morgan; G. Murphy; M. F. Nave; L. Nickesson; P. Nielson; P. Noll; S. Nowak; W. Obert; B. Oliver; M. Olsson; J. O'Rourke; M. G. Pacco; J. Paillere; L. Pannacione; S. Papastergiou; D. Pasini; M. Pescatore; J. Planncoulaine; J. P. Poffe; R. Prentice; T. Raimondi; C. Raymond; P. H. Rebut; J. Removille; W. Riediker; R. Roberts; A. Rolfe; R. T. Ross; G. Sadler; J. Saffert; N. Salmon; A. Sand; A. Santagiustina; R. Saunders; M. Schmid; F. C. Schueller; K. Selin; R. Shaw; D. Sigournay; R. Simonini; P. Smeulders; L. Sonnerup; K. Sonnenberg; M. Stamp; C. A. Steed; D. Stork; P. E. Stott; T. E. Stringer; D. Summers; A. Tanga; A. Taroni; A. Terrington; A. Tesini; P. R. Thomas; E. Thompson; F. Tibone; R. Tivery; E. Usselmann; H. Van der Beken; M. Von Hellerman; J. E. Van Montfoort; T. Wade; C. Walker; B. A. Wallander; M. Walravens; K. Walter; M. L. Watkins; M. Watson; D. Webberley; J. Wesson; J. Wilks; T. Winkel; C. Woodward; M. Wykes; D. Young; L. Zennelili; J. Zwart; B. Beaumont; D. Gambier; D. Moreau; J. Ehrenberg; H. Jaeckel; S. Kissel; U. Kuephnapfel; R. Mueller; A. Staebler; A. Weller; J. H. Hamnen; M. Evrared; M. Gadeberg; K. Thomsen; P. Dupperrex; G. Tonetti; N. Lopez-Cardozo; B. Tubbing; J. Von Seggern; J. Tagle; F. Bombarda; G. Bracco; R. Giannella; R. Carolan; M. Cox; M. Forrest; D. Goodall; N. Hawkes; P. Haynes; J. Hugill; K. D. Lawson; G. McCracken; J. Partridge; N. Peacock; J. Snipes; T. Todd; H. Schamel; H. Summers; S. Tsuji; G. Tallents

1986-01-01

370

Multiple jet study  

NASA Technical Reports Server (NTRS)

Test data is presented which allows determination of jet penetration and mixing of multiple cold air jets into a ducted subsonic heated mainstream flow. Jet-to-mainstream momentum flux ratios ranged from 6 to 60. Temperature profile data is presented at various duct locations up to 24 orifice diameters downstream of the plane of jet injection. Except for two configurations, all geometries investigated had a single row of constant diameter orifices located transverse to the main flow direction. Orifice size and spacing between orifices were varied. Both of these were found to have a significant effect on jet penetration and mixing. The best mixing of the hot and cold streams was achieved with duct height.

Walker, R. E.; Kors, D. L.

1973-01-01

371

Description of Jet Breakup  

NASA Technical Reports Server (NTRS)

In this article we review recent results on the breakup of cylindrical jets of a Newtonian fluid. Capillary forces provide the main driving mechanism and our interest is in the description of the flow as the jet pinches to form drops. The approach is to describe such topological singularities by constructing local (in time and space) similarity solutions from the governing equations. This is described for breakup according to the Euler, Stokes or Navier-Stokes equations. It is found that slender jet theories can be applied when viscosity is present, but for inviscid jets the local shape of the jet at breakup is most likely of a non-slender geometry. Systems of one-dimensional models of the governing equations are solved numerically in order to illustrate these differences.

Papageorgiou, Demetrios T.

1996-01-01

372

Jet physics at CDF  

SciTech Connect

We present high E{sub T} jet measurements from CDF at the Fermilab Tevatron Collider. The incfilusive jet cross section at {radical}s = 1800 GeV with {approximately} 5 times more data is compared to the published CDF results, preliminary D0 results, and next-to-leading order QCD predictions. The {summation}E{sub T} cross section is also compared to QCD predictions and the dijet angular distribution is used to place a limit on quark compositeness. The inclusive jet cross section at {radical}s = 630 GeV is compared with that at 1800 GeV to test the QCD predictions for the scaling of jet cross sections with {radical}s. Finally, we present momentum distributions of charged particles in jets and compare them to Modified Leading Log Approximation predictions.

Melese, P.

1997-05-01

373

Jet Lag in Athletes  

PubMed Central

Context: Prolonged transmeridian air travel can impart a physical and emotional burden on athletes in jet lag and travel fatigue. Jet lag may negatively affect the performance of athletes. Study Type: Descriptive review. Evidence Acquisition: A Medline search for articles relating to jet lag was performed (1990-present), as was a search relating to jet lag and athletes (1983-January, 2012). The results were reviewed for relevance. Eighty-nine sources were included in this descriptive review. Results: Behavioral strategies are recommended over pharmacological strategies when traveling with athletes; pharmacological aides may be used on an individual basis. Strategic sleeping, timed exposure to bright light, and the use of melatonin are encouraged. Conclusions: There is strong evidence that mood and cognition are adversely affected by jet lag. Some measures of individual and team performance are adversely affected as well.

Lee, Aaron; Galvez, Juan Carlos

2012-01-01

374

Instability of rectangular jets  

NASA Technical Reports Server (NTRS)

The instability of rectangular jets is investigated using a vortex sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

Tam, Christopher K. W.; Thies, Andrew T.

1992-01-01

375

A liquid rate gyroscope using electro-conjugate fluid  

Microsoft Academic Search

We previously proposed a concept of a novel liquid rate gyroscope using electro-conjugate fluid (ECF) [11]. The ECF is a dielectric fluid which works here as a functional\\/smart fluid generating a powerful jet flow under a strong DC electric field. The ECF liquid rate gyroscope proposed uses the drift of the ECF jet due to Coriolis force when an angular

Shinichi Yokota; Tsunehiko Imamura; Kenjiro Takemura; Kazuya Edamura; Hideo Kumagai

2008-01-01

376

High sensitivity UV fluorescence spectroscopy based on an optofluidic jet waveguide.  

PubMed

A novel spectroscopic sensor based on an optofluidic liquid jet waveguide is presented. In this device, a liquid jet waveguide is generated with the solution under analysis. This stream, exploiting total internal reflection, acts as an optical waveguide confining the autofluorescence light produced by chemical or biological samples when opportunely excited. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the fluorescence towards the detection system. Experimental measurements have been performed using an UV excitation source on water solutions containing representative water pollutants as aromatic hydrocarbons or bacteria showing very low limit of detection. PMID:24104332

Persichetti, Gianluca; Gesta, Genni; Bernini, Romeo

2013-10-01

377

Optimal Jet Finder  

NASA Astrophysics Data System (ADS)

We describe a FORTRAN 77 implementation of the optimal jet definition for identification of jets in hadronic final states of particle collisions. We discuss details of the implementation, explain interface subroutines and provide a usage example. The source code is available from http://www.inr.ac.ru/~ftkachov/projects/jets/. Program summaryTitle of program: Optimal Jet Finder (OJF_014) Catalogue identifier: ADSB Program Summary URL:http://cpc.cs.qub.ac.uk/summaries/ADSB Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer: Any computer with the FORTRAN 77 compiler Tested with: g77/Linux on Intel, Alpha and Sparc; Sun f77/Solaris (thwgs.cern.ch); xlf/AIX (rsplus.cern.ch); MS Fortran PowerStation 4.0/Win98 Programming language used: FORTRAN 77 Memory required: ˜1 MB (or more, depending on the settings) Number of bytes in distributed program, including examples and test data: 251 463 Distribution format: tar gzip file Keywords: Hadronic jets, jet finding algorithms Nature of physical problem: Analysis of hadronic final states in high energy particle collision experiments often involves identification of hadronic jets. A large number of hadrons detected in the calorimeter is reduced to a few jets by means of a jet finding algorithm. The jets are used in further analysis which would be difficult or impossible when applied directly to the hadrons. Grigoriev et al. [ hep-ph/0301185] provide a brief introduction to the subject of jet finding algorithms and a general review of the physics of jets can be found in [Rep. Prog. Phys. 36 (1993) 1067]. Method of solution: The software we provide is an implementation of the so-called optimal jet definition ( OJD). The theory of OJD was developed by Tkachov [Phys. Rev. Lett. 73 (1994) 2405; 74 (1995) 2618; Int. J. Mod. Phys. A 12 (1997) 5411; 17 (2002) 2783]. The desired jet configuration is obtained as the one that minimizes ? R, a certain function of the input particles and jet configuration. Restrictions on the complexity of the program: The size of the largest data structure the program uses is (maximal number of particles in the input) × (maximal number of jets in the output) × 8 bytes. (For the standard settings <1 MB). Therefore, there is no memory restriction for any conceivable application for which the program was designed. Typical running time: The running time depends strongly on the physical process being analyzed and the parameters used. For the benchmark process we studied, e+e-? W+W-? 4 jets , with the average number of ˜80 particles in the input, the running time was <10 -2 s on a modest PC (per event with ntries=1). For a fixed number of jets the complexity of the algorithm grows linearly with the number of particles (cells) in the input, in contrast with other known jet finding algorithms for which this dependence is cubic. The reader is referred to Grigoriev et al. [ hep-ph/0301185] for a more detailed discussion of this issue.

Grigoriev, D. Yu.; Jankowski, E.; Tkachov, F. V.

2003-09-01

378

On the electrospraying of conducting liquids in dielectric liquid baths  

NASA Astrophysics Data System (ADS)

Steady cone-jets of conducting liquids inside dielectris liquid baths are easily obtained. In particular water and glycerol have been electrosprayed in either heptane or vaseline oil. Experimental results show that the current emitted from the cone-jet depends on the flow rate and the liquid properties in the same way that it does in air. On the contrary, the effects of the bath inertia plays an important role to determine the size of droplets. Also the addition of small amounts of both water-soluble and lipid-soluble surfactants changes appreciably the spray characteristics. The influence of either lipid-soluble or water soluble surfactants at different concentrations on the droplet size of a water electrospray in oil or heptane has been experimentally obtained. In the case of glycerol, the high viscosity of the fluid gives rise to very long jets presenting kink instabilitiy far from the vertex cone. Much more stable jets are obtained by adding small amounts of lipid or water-soluble surfactants. In those cases, the electric field on the very long jet of glycerol is very small and a big droplet is formed at the end of the jet.

Gómez-Marín, Álvaro; Loscertales, Ignacio G.; Márquez, Manuel; Barrero, Antonio

2004-11-01

379

Rapid leak detection with liquid crystals  

NASA Technical Reports Server (NTRS)

Small leaks in vacuum lines are detected by applying liquid-crystal coating, warming suspected area, and observing color change due to differential cooling by leak jet. Technique is used on inside or outside walls of vacuum-jacketed lines.

Heisman, R. M.; Iceland, W. F.; Ruppe, E. P.

1978-01-01

380

Relativistic jets from supernovae  

NASA Astrophysics Data System (ADS)

Stars with masses greater than eight times the Sun's explode as supernovae when they fail to extract energy from nuclear fusion. Some of these supernova progenitors shed their outermost hydrogen envelope and acquire high rates of rotation at their cores before they explode. During a supernova collapse phase these stars form a dense disk of material around a degenerate core, which in turn powers energetic jets of material that propagate through the stellar atmosphere outwards. These jets soon acquire bulk speeds close to the speed of light. We perform a detailed analysis of numerical, hydrodynamic simulations of these jets to determine their stability to pressure waves that grow as Kelvin- Helmholtz modes from the interface between the jet and the stellar medium. We have discovered that the pressure profile of the star makes these jets unstable to such modes just before the jet breaks out compared to the region closest to the center. We have also discovered that only the most energetic jets predicted in this theory support such modes over the time it takes for the jet to reach the stellar surface. When we follow the jets in the numerical simulations as they break out, we calculate that they become relativistic winds that carry within them enhancements in their pressure and velocity, which can turn into internal shocks. These shocks could accelerate charged particles that cool through gamma ray emission and thus convert the kinetic energy of the wind into radiation that we can detect as a long gamma-ray burst. However, we have found that the fastest moving core of this wind is unlikely to produce substantial internal shocks. Shocks are most likely to happen at an angle from the center of a conical wind. We present a test of this model for such emission geometry and its corresponding rate for detected gamma ray bursts above a given gamma-ray flux.

Gomez, Enrique Alberto

381

The counter-jet formation in an air bubble induced by the impact of shock waves  

Microsoft Academic Search

The interaction of an air bubble (isolated in water or attached to a boundary) with shock waves induced by electric sparks is investigated by high-speed photography. The interaction is closely related to the counter-jet induced by the impact of shock waves. The formation of a counter-jet in an air bubble is related to the liquid jet formed in the same

Li-xin BAI; Wei-lin XU; Chao LI; Yan-dong GAO

2011-01-01

382

The shape function of a free-falling laminar jet: Making use of Bernoulli's equation  

NASA Astrophysics Data System (ADS)

The shape function of a laminar liquid jet issuing from a circular orifice and falling vertically in air under gravity is analyzed. The diameter of the jet is observed to decrease with the axial distance from the nozzle. The governing equation for variation of the jet radius with the axial coordinate is derived from a modified Bernoulli's law, including the interfacial energy density and viscous losses. The analytical solution found in terms of dimensionless group numbers agrees well with experimental data.

Massalha, Taha; Digilov, Rafael M.

2013-10-01

383

JET ohmic heating circuit  

SciTech Connect

This paper describes the JET Ohmic Heating Circuit - a switching network in the Poloidal System of the JET Machine - that connects the driving energy source to the JET Torus to induce and maintain the plasma current. The sequential operation, including the protective action, is described. The basic design aspects for all components are reviewed and the status of manufacture and procurement presented. The components will be installed in 1982 and the whole system will be commissioned under CODAS remote control to be ready by Spring 1983.

Helgesen, H.; Mondino, P.L.; Raymond, C.; Stella, A.

1981-01-01

384

Water jet symposium  

SciTech Connect

A symposium is presented dealing with the theoretical and experimental aspects of high pressure water jet cutting technology and its application to mining and civil engineering, as well as for industrial use. The application of water jets is diversified. The mining industry is already using water jets for development and production drilling in uranium, and is working on applying borehole mining to production of uranium and coal. Seven papers from this symposium have been abstracted and indexed individually for the US Department of Energy's Energy Data Base. (JMT)

Wang, F.D.; Ozdemir, L.; Miller, R. (eds.)

1982-01-01

385

Experimental Study on Thermal Interaction of Ethanol Jets in High Temperature Fluorinert  

NASA Astrophysics Data System (ADS)

As a fundamental study for the direct contact heat exchange which was employed for in-vessel heat exchange in the Pb-Bi-cooled direct contact boiling water small fast reactor (PBWFR) and for the steam generator tube rupture (SGTR) accident in lead alloy-cooled fast reactor (LFR), ethanol jet was injected into high temperature fluorinert (FC-3283) as a simulation experiment in order to investigate the jet boiling phenomena just after volatile water contacting with the high temperature continuous lead alloy liquid. Two series of tests (no-boiling and boiling) were initiated to evaluate the ethanol vapor volume which generated around the ethanol jet. From synchronized temperature measurement around ethanol jet, the overview of the boiling behavior showed that jet boiling occurred at bottom part of jet first and developed to the upper part within very narrow area around jet.

Sa, Rongyuan; Takahashi, Minoru

386

An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine  

Microsoft Academic Search

Coaxial jets are commonly used as injectors in propulsion and combustion devices due to both the simplicity of their geometry and the rapid mixing they provide. In liquid rocket engines it is common to use coaxial jets in the context of airblast atomization. However, interest exists in developing rocket engines using a full flow staged combustion cycle. In such a

Stephen Alexander Schumaker

2009-01-01

387

Numerical study on the design parameters of a jet ejector for absorption systems  

Microsoft Academic Search

The purpose of incorporating a jet ejector into an absorption system is to improve the preabsorption of the refrigerant coming from the evaporator by the weak solution, i.e., to improve the overall absorption process. The mixing process in the jet ejector is very intensive as a result of spray generation of the liquid phase and of extensive subcooling of the

A. Levy; M. Jelinek; I. Borde

2002-01-01

388

Comparison of Inconel 625 and Inconel 600 in resistance to cavitation erosion and jet impingement erosion  

Microsoft Academic Search

Liquid droplet erosion (LDE), which often occurs in bellows made of nickel-based alloys, threatens the security operation of the nuclear power plant. As the candidate materials of the bellows, Inconel 600 and Inconel 625 were both tested for resistance to cavitation erosion (CE) and jet impingement erosion (JIE) through vibratory cavitation equipment and a jet apparatus for erosion-corrosion. Cumulative mass

H. X. Hu; Y. G. Zheng; C. P. Qin

2010-01-01

389

Thermal stability of coal-derived jet fuels in the autoxidative and pyrolytic regimes  

Microsoft Academic Search

Coal-based liquids have a great potential as precursors for advanced jet fuels that meet the more stringent thermal stability requirements for the future high-Mach jet aircraft. In current commercial planes, the fuel may be exposed to temperatures up to 300 C. However, as the flight speed will be increased to high Mach numbers, the fuel is expected to experience temperatures

J. M. Andresen; J. J. Strohm; C. Song

1999-01-01

390

Dilution jet mixing program  

NASA Technical Reports Server (NTRS)

Parametric tests were conducted to quantify the mixing of opposed rows of jets (two-sided injection) in a confined cross flow. Results show that jet penetrations for two sided injections are less than that for single-sided injections, but the jet spreading rates are faster for a given momentum ratio and orifice plate. Flow area convergence generally enhances mixing. Mixing characteristics with asymmetric and symmetric convergence are similar. For constant momentum ratio, the optimum S/H(0) with in-line injections is one half the optimum value for single sided injections. For staggered injections, the optimum S/H(0) is twice the optimum value for single-sided injection. The correlations developed predicted the temperature distributions within first order accuracy and provide a useful tool for predicting jet trajectory and temperature profiles in the dilution zone with two-sided injections.

Srinivasan, R.; Coleman, E.; Johnson, K.

1984-01-01

391

Jet lag prevention  

MedlinePLUS

... your internal clock before you travel. While in flight: Don't sleep unless it matches the bedtime ... decrease jet lag. If you will be in flight during the bedtime of your destination, take some ...

392

Enhanced boiling heat transfer by a submerged vibration-induced jet  

NASA Astrophysics Data System (ADS)

A novel, vibration-induced turbulent jet has been developed to enhance the boiling heat transfer process from a horizontal surface. The turbulent jet was formed by oscillating an 18.2 mm diameter brass piezoelectric diaphragm so that its surface acceleration exceeded 3200 g. The resulting pressure oscillations in the liquid caused the time-periodic formation and collapse of cavitation bubbles that generated the turbulent jet. When the diaphragm was positioned approximately 5 to 10 mm away from a heated surface, the direct impingement of the turbulent jet would dislodge small vapor bubbles from the surface. To test the performance of this jet in a heat transfer process, a small-scale vibration-induced actuator that produced a submerged liquid jet directed at a thermal test die was constructed. Without the jet present, the test die dissipated 36.2 W/cm^2 at 115 ^rcC when submerged in dearated distilled water. With the jet diaphragm positioned approximately 9 mm from the thermal test die, the turbulent jet increased the heat flux to 119 W/cm^2 at the same die temperature, a 230% improvement. Future work will include characterizing the heat transfer capabilities of the turbulent jet when operating at pressures lower than atmospheric.

Tillery, Steven W.; Heffington, Samuel N.; Smith, Marc K.; Glezer, Ari

2003-11-01

393

Jets in hadronic reactions  

SciTech Connect

Recent experimental data on the properties of jets in hadronic reactions are reviewed and compared with theoretical expectations. Jets are clearly established as the dominant process for high E/sub T/ events in hadronic reactions. The cross section and the other properties of these events are in qualitative and even semiquantitative agreement with expectations based on perturbative QCD. However, we can not yet make precise tests of QCD, primarily because there are substantial uncertainties in the theoretical calculations. 45 references. (WHK)

Paige, F.E.

1983-01-01

394

Fundamental properties of light-emitting liquid crystal cells operated under alternating voltage  

NASA Astrophysics Data System (ADS)

We have investigated the fundamental operation characteristics of light-emitting liquid crystals with an emissive layer of fluorescent dye-doped nematic liquid crystal under the condition of applied AC voltage. The electric field dependent current and luminance properties for different frequencies are satisfactorily explained by an equivalent circuit analysis. We confirm that the luminance steeply plunges as the frequency increases. Such a great suppression is explained by accounting for the cut-off properties of the equivalent circuit and for the effect of ions drift mobility.

Honma, Michinori; Horiuchi, Takao; Nose, Toshiaki

2013-08-01

395

Radiation from Relativistic Jets  

NASA Technical Reports Server (NTRS)

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

2008-01-01

396

Relativistic Jets from Collapsars.  

PubMed

Using a collapsar progenitor model of MacFadyen & Woosley, we have simulated the propagation of an axisymmetric jet through a collapsing rotating massive star with the GENESIS multidimensional relativistic hydrodynamic code. The jet forms as a consequence of an assumed (constant or variable) energy deposition in the range of 1050-1051 ergs s-1 within a 30 degrees cone around the rotation axis. The jet flow is strongly beamed (approximately less than a few degrees), spatially inhomogeneous, and time dependent. The jet reaches the surface of the stellar progenitor (R*=2.98x1010 cm) intact. At breakout, the maximum Lorentz factor of the jet flow is 33. After breakout, the jet accelerates into the circumstellar medium, whose density is assumed to decrease exponentially and then become constant, rhoext=10-5 g cm-3. Outside the star, the flow begins to expand laterally also (v approximately c), but the beam remains very well collimated. At a distance of 2.54 R*, where the simulation ends, the Lorentz factor has increased to 44. PMID:10688767

Aloy; Müller; Ibáñez; Martí; MacFadyen

2000-03-10

397

Temporal instability analysis of inviscid compound jets falling under gravity  

NASA Astrophysics Data System (ADS)

Compound liquid jets can be used in a variety of industrial applications ranging from capsule production in pharmaceutics to enhance printing methods in ink-jet printing. An appreciation of how instability along compound jets can lead to breakup and droplet formation is thus critical in many fields in science and engineering. In this paper, we perform a theoretical analysis to examine the instability of an axisymmetric inviscid compound liquid jet which falls vertically under the influence of gravity. We use a long-wavelength, slender-jet asymptotic expansion to reduce the governing equations of the problem into a set of one-dimensional partial differential equations, which describe the evolution of the leading-order axial velocity of the jet as well as the radii of both the inner and the outer interfaces. We first determine the steady-state solutions of the one-dimensional model equations and then we perform a linear temporal instability analysis to obtain a dispersion relation, which gives us useful information about the maximum growth rate and the maximum wavenumber of the imposed wave-like disturbance. We use our results to estimate the location and qualitative nature of breakup and then compare our results with numerical simulations.

Mohsin, Muhammad; Uddin, Jamal; Decent, Stephen P.; Afzaal, Muhammad F.

2013-01-01

398

A unified approach to bubbling-jetting phenomena in powder injection into iron and steel  

Microsoft Academic Search

The injection of powder into liquids has been investigated by physical modeling and by multi-phase fluid dynamic modeling.\\u000a The transition from gas-particle jets which penetrate deeply into the liquid and a gas bubbling regime was found to depend\\u000a on the coupling between gas and particle phases in the conveying line; fine particles at high loading couple well and form\\u000a jets,

L. R. Farias; G. A. Irons

1985-01-01

399

Electric measurements of charged sprays emitted by cone-jets  

NASA Astrophysics Data System (ADS)

We use time-of-flight and energy analysis techniques to measure in a vacuum the charge, specific charge and stopping potential of primary and satellite droplets generated by electrosprays of tributyl phosphate solutions. This information, of interest in itself, is subsequently analysed to obtain the following relevant parameters of the jet emanating from the Taylor cone: the velocity of the fluid at the breakup point, the voltage difference between the liquid cone and jet breakup location, and the most probable wavelength for varicose breakup. A large fraction of the electrospray needle voltage is used to accelerate the jet. Indeed, for the solutions of lowest electrical conductivities studied here, the voltage difference between electrospray needle and jet breakup location becomes approximately 90% of the needle voltage. In addition, the pressure of the jet fluid at the breakup point is negligible compared to its specific kinetic energy. The specific charge distribution function of the main droplets produced in the varicose breakup is remarkably narrow. Hence, the limiting and commonly accepted case of varicose breakup at constant electric potential is not consistent with this experimental observation. On the other hand, a scenario in which the electric charge is bound to the jet surface seems to be a good approximation to simulate the effect of charge on capillary breakup. It is also found that the effect of viscosity on the formation of droplets is paramount in electrosprays of moderate and high electrical conductivity. We expect that these measurements will guide the analytical modelling of cone-jets.

Gamero-Castaño, Manuel; Hruby, Vladimir

2002-05-01

400

Film-free laser printing: Jetting dynamics analyzed through time-resolved imaging  

NASA Astrophysics Data System (ADS)

The film-free laser-based microprinting technique allows high-resolution printing of transparent liquids without the need for the preparation of the liquid in thin-film form. Its operating principle relies on the tight focusing of ultrashort laser pulses in the liquid free-surface proximity producing upon absorption a rapidly expanding cavitation bubble that generates the ejection of micrometric liquid jets. While the technique proves feasible for microprinting, a deeper understanding of the influence on the printing process of its most relevant technological parameters is required. Therefore, in this work we analyze through time-resolved imaging the laser pulse energy influence on the bubble-jet dynamics of a film-free liquid ejection event. We simultaneously image the evolution of both cavitation bubble and ejected liquid, showing that for all the analyzed energies the transfer mechanism is mediated by the formation of two liquid jets which originate during the successive expansion-collapse cycles that the cavitation bubble undertakes close to the liquid free-surface. We find that the evolution of both bubble and jets depends strongly on the energy. The different bubble geometries that appear are interpreted in terms of the counter-jet interaction with the bubble, which in its turn depends on the energy.

Patrascioiu, A.; Fernández-Pradas, J. M.; Morenza, J. L.; Serra, P.

2014-05-01

401

Integrated coke, asphalt and jet fuel production process and apparatus  

DOEpatents

A process and apparatus for the production of coke, asphalt and jet fuel m a feed of fossil fuels containing volatile carbon compounds therein is disclosed. The process includes the steps of pyrolyzing the feed in an entrained bed pyrolyzing means, separating the volatile pyrolysis products from the solid pyrolysis products removing at least one coke from the solid pyrolysis products, fractionating the volatile pyrolysis products to produce an overhead stream and a bottom stream which is useful as asphalt for road pavement, condensing the overhead stream to produce a condensed liquid fraction and a noncondensable, gaseous fraction, and removing water from the condensed liquid fraction to produce a jet fuel-containing product. The disclosed apparatus is useful for practicing the foregoing process. the process provides a useful method of mass producing and jet fuels from materials such as coal, oil shale and tar sands.

Shang, Jer Y. (McLean, VA)

1991-01-01

402

Kinetic disposition of an emulsifiable concentrate formulation of deltamethrin applied to sheep in a plunge-dip and its effect on lice.  

PubMed

An emulsifiable concentrate formulation of the synthetic pyrethroid insecticide deltamethrin was applied in a plunge dip, 3 weeks after shearing, to a group of 5 Merino sheep infested with sheep body lice, Bovicola ovis. Deltamethrin concentrations on the wool were measured at regular intervals between 1 and 98 days after treatment and were not significantly different (P > 0.05) between sites on the dorsal mid-line, upper or lower flank. Levels in the tip of the fleece were significantly greater than those in the base, indicating that there was little movement of deltamethrin down the staple as the wool grew. Most lice were killed after 20 h of exposure in vitro to wool samples collected between 1 and 28 days after treatment. However, many lice survived in samples containing a similar concentration of deltamethrin, but collected between 35 and 98 days after treatment. Numbers of lice surviving increased with the sampling time after treatment, suggesting that the bioavailability of the deltamethrin changed as the insecticide aged in the fleece. Some transfer of deltamethrin occurred from treated to untreated sheep. The levels of deltamethrin were higher in sheep placed in contact with the treated group at 14 days after treatment than in those which were in contact from 43 days after treatment. PMID:8719957

Johnson, P W; Darwish, A; Dixon, R; Steel, J W

1995-12-01

403

Cryogenically assisted abrasive jet micromachining of polymers  

NASA Astrophysics Data System (ADS)

The abrasive jet micromachining (AJM) of elastomers and polymers such as polydimethylsiloxane (PDMS), acrylonitrile butadiene styrene (ABS) and polytetrafluoroethylene (PTFE) for use in micro-fluidic devices was found to be very slow or impossible at room temperature. To enhance the material removal rate in such materials, a stream of liquid nitrogen (LN2) was injected into the abrasive jet, cooling the target to cryogenic temperatures. Erosion rate measurements on the three polymeric materials (PDMS, ABS and PTFE) with and without the use of LN2 were compared along with the profiles of micromachined channels and holes. It was found that the use of LN2 cooling caused brittle erosion in PDMS, allowing it to be micromachined successfully. An erosion rate increase was also observed in PTFE and ABS at high and intermediate impact angles. The use of LN2 also was found to reduce particle embedding.

Getu, H.; Spelt, J. K.; Papini, M.

2008-11-01

404

Nanofiber Assembly by Rotary Jet-Spinning  

PubMed Central

High voltage electrical fields and low production rate limit electrospinning, the electrical charging of polymer liquids, as a means of nanofiber fabrication. Here, we show a facile method of fabrication of aligned 3D nanofiber structures by utilizing high speed, rotating polymer solution jets to extrude fibers. Termed rotary jet-spinning, fiber morphology, diameter and web porosity can be controlled by varying nozzle geometry, rotation speed, and polymer solution properties. We demonstrate the utility of this technique for tissue engineering by building anisotropic arrays of biodegradable polymer fibers and seeding the constructs with neonatal rat ventricular cardiomyocytes. The myocytes used the aligned fibers to orient their contractile cytoskeleton and to self-organize into a beating, multicellular tissue that mimics the laminar, anisotropic architecture of the heart muscle. This technique may prove advantageous for building uniaxially-aligned nanofiber structures for polymers which are not amenable to fabrication by electrospinning.

Badrossamay, Mohammad Reza; McIlwee, Holly Alice; Goss, Josue A.; Parker, Kevin Kit

2010-01-01

405

A circulating system for a steam jet refrigeration system  

Microsoft Academic Search

This paper proposes a circulating system for a steam jet refrigeration system that does not require mechanical power. In this system, the liquid from the condenser is fed to the boiler by means of the boiler pressure and gravity force. This feeding system was tested separately. It was found that the heat input to the boiler was relatively similar to

Passakorn Srisastra; Satha Aphornratana

2005-01-01

406

Large Eddy Simulation of jets laden with evaporating drops  

NASA Technical Reports Server (NTRS)

LES of a circular jet laden with evaporating liquid drops are conducted to assess computational-drop modeling and three different SGS-flux models: the Scale Similarity model (SSC), using a constant coefficient calibrated on a temporal mixing layer DNS database, and dynamic-coefficient Gradient and Smagorinsky models.

Leboissetier, A.; Okong'o, N.; Bellan, J.

2004-01-01

407

Steam-Jet High-Vacuum Pump (Parostruynyi Vysokovakuumnyi Nasos).  

National Technical Information Service (NTIS)

Description of a vapor-jet high-vacuum pump using fused metals as the working liquids, these being the eutectic alloys of cadmium and tin (Cd--Sn) or zinc and tin (Zn--Sn) which has the distinguishing feature that for the purpose of returning the working ...

E. N. Martinson K. N. Myznikov V. A. Romanenko

1967-01-01

408

B-jets and z + b-jets at CDF  

SciTech Connect

The authors present CDF cross-section measurements for the inclusive production of b jets and the production of b jets in association with a Z{sup 0} boson. Both measurements are in reasonable agreement with NLO QCD predictions.

Jeans, Daniel; /Rome U.

2006-06-01

409

The M87 Jet. "Rosetta Stone" of AGN Jets  

NASA Astrophysics Data System (ADS)

We investigate the structure and dynamics of the M87 jet based on multi-frequency VLBI observations and MHD jet theories. Millimeter VLBI cores are considered as innermost jet emissions. The jet structure up to ~ 105 rs is described as a parabolic streamline, indicating the lateral expansion under a confinement by the stratified ISM. Thus, the jet collimation maintains in five orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 rs. We here examine the jet parabolic structure in order to identify the property of a bulk acceleration; observed sub-to-superluminal motions indicate an MHD acceleration from non-relativistic to relativistic regimes. We propose that the M87 jet consists of Poynting-flux dominated flows, powered by nonlinear torsional Alfvén waves. Future sub-mm VLBI observations play an important role in resolving the origin of the M87 jets.

Nakamura, Masanori; Asada, Keiichi

2013-12-01

410

Two-valued breakup length of a water jet issuing from a finite-length nozzle under normal gravity.  

PubMed

Laboratory experiments are conducted in which water is issued vertically downward from a finite-length nozzle at a constant speed using a piston. The results of these experiments indicate that the breakup length of the liquid jet is two-valued at Weber numbers greater than unity but less than a certain value, which depends on the nozzle length-to-radius ratio and the Bond number. In addition to a long breakup length, which is consistent with the conventional observation, another shorter breakup length is realized at the same jet issue speed. Each experimental run for a specific jet issue speed begins from the start of liquid issue so that each run is independent of the other runs. Transition between the two breakup lengths seldom occurs in each run. Which of the two breakup lengths occurs is determined at the start of liquid issue, when the capillary wave produced by the liquid jet tip contraction easily reaches the nozzle exit. Unlike the conventional belief, which is based on the Plateau-Rayleigh instability theory, this experimental evidence demonstrates that liquid jet disintegration occurs in a deterministic manner. The previously proposed self-destabilizing mechanism of a liquid jet in microgravity, in which the origin of the unstable wave responsible for the breakups is attributed to the formation of an upstream propagating capillary wave at every breakup, is extended to explore the physics underlying the observed liquid jet disintegration behaviors. PMID:22060494

Umemura, Akira; Kawanabe, Sho; Suzuki, Sousuke; Osaka, Jun

2011-09-01

411

The Twin Jet Nebula  

NASA Technical Reports Server (NTRS)

M2-9 is a striking example of a 'butterfly' or a bipolar planetary nebula. Another more revealing name might be the 'Twin Jet Nebula.' If the nebula is sliced across the star, each side of it appears much like a pair of exhausts from jet engines. Indeed, because of the nebula's shape and the measured velocity of the gas, in excess of 200 miles per second, astronomers believe that the description as a super-super-sonic jet exhaust is quite apt. This is much the same process that takes place in a jet engine: The burning and expanding gases are deflected by the engine walls through a nozzle to form long, collimated jets of hot air at high speeds. M2-9 is 2,100 light-years away in the constellation Ophiucus. The observation was taken Aug. 2, 1997 by the Hubble telescope's Wide Field and Planetary Camera 2. In this image, neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue.

1997-01-01

412

Jet propulsion without inertia  

NASA Astrophysics Data System (ADS)

A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e., jetting) surfaces are considered and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number, which corresponds to the potential flow created by a source dipole at the sphere center. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria.

Spagnolie, Saverio E.; Lauga, Eric

2010-08-01

413

Jet penetration in glass  

SciTech Connect

We describe a phenomenological model which accounts for the mechanical response of glass to intense impulsive loading. An important aspect of this response is the dilatancy accompanying fracture. We have also conducted a number of experiments with 38.1-mm diameter precision shaped charges to establish the performance against various targets and to allow evaluation of our model. At 3 charge diameters standoff, the data indicate that both virgin and damaged glass offer better (Bernoulli-scaled) resistance to penetration than either of 4340 steel, or 6061-T6 aluminum alloy. Time-resolved measurements indicate two distinct phases of jet penetration in glass: An initial hydrodynamic phase, and a second phase characterized by a slower penetration velocity. Our calculations show that at early time, a crater is formed around the jet and only the tip of the undisturbed jet interacts with the glass. At late time the glass has collapsed on the jet and degraded penetration continues via a disturbed and fragmented jet.

Moran, B.; Glenn, L.A.; Kusubov, A.

1991-05-01

414

Instability of rectangular jets  

NASA Technical Reports Server (NTRS)

The instability of rectangular jets is investigated using a vortex-sheet model. It is shown that such jets support four linearly independent families of instability waves. Within each family there are infinitely many modes. A way to classify these modes according to the characteristics of their mode shapes or eigenfunctions is proposed. It is demonstrated that the boundary element method can be used to calculate the dispersion relations and eigenfunctions of these instability wave modes. The method is robust and efficient. A parametric study of the instability wave characteristics has been carried out. A sample of the numerical results is reported here. It is found that the first and third modes of each instability wave family are corner modes. The pressure fluctuations associated with these instability waves are localized near the corners of the jet. The second mode, however, is a center mode with maximum fluctuations concentrated in the central portion of the jet flow. The center mode has the largest spatial growth rate. It is anticipated that as the instability waves propagate downstream the center mode would emerge as the dominant instability of the jet.

Tam, Christopher K. W.; Thies, Andrew T.

1993-01-01

415

Shaped Charge Jet Stability and Penetration Calculations.  

National Technical Information Service (NTIS)

This present study focuses on two important aspects of shaped charge mechanics, jet breakup and broken jet penetration. The jet breakup problem is studied from a stability approach. A one-dimensional stability theory for stretching plastic jets is present...

J. Carleone P. Chou R. D. Ciccarelli

1977-01-01

416

Aeroacoustic Experiments with Twin Jets  

NASA Technical Reports Server (NTRS)

While the noise produced by a single jet is azimuthally symmetric, multiple jets produce azimuthally varying far-field noise. The ability of one jet to shield another reduces the noise radiated in the plane of the jets, while often increasing the noise radiated out of the plane containing the jets. The present study investigates the shielding potential of twin jet configurations over subsonic and over-expanded supersonic jet conditions with simulated forward flight. The experiments were conducted with 2 in. throat diameter nozzles at four jet spacings from 2.6d to 5.5d in center-to-center distance, where d is the nozzle throat diameter. The current study found a maximum of 3 dB reduction in overall sound pressure level relative to two incoherent jets in the peak jet noise direction in the plane containing the jets. However, an increase of 3 dB was found perpendicular to the plane containing the jets. In the sideline direction, shielding is observed for all jet spacings in this study.

Bozak, Richard F.; Henderson, Brenda S.

2012-01-01

417

Kt -- jets and jet structure and fragmentation at the Tevatron  

SciTech Connect

Kt algorithms are now used by both D0 and CDF to study jets. A preliminary study of jet structure for data taken by D0 and CDF during run 1 (92-95) is presented. D0 has measured the jet mass as a function of jet p{sub T}. The CDF measurement of inclusive charged particle momentum distributions is in agreement with the Modified Leading Log Approximation (MLLA).

Beretvas, A.

1997-12-31

418

Water Jet Cutting Related to Jet & Rock Properties  

Microsoft Academic Search

A continuous water jet is used to cut slots in seven rock types in an experiment, which correlates jet and rock properties with jet performance. The jet, operating at pressures from 5,000 to 25,000 psi is traversed across the rock surface at speeds between 15 and 750 ft\\/min. The rock properties considered in the analysis are uniaxial compressive strength, Young's

David A. Summers

1972-01-01

419

Elliptic jets. I - Characteristics of unexcited and excited jets  

NASA Technical Reports Server (NTRS)

Experimental studies of incompressible elliptic jets of different aspect ratios and initial conditions are summarized along with the effects of excitations at selected frequencies and amplitudes. The experimental facilities and procedures are described and jet spread and decay are discussed. The instability of elliptic shear layers, the behavior of the jet column under controlled excitation, and the time-average measures of unexcited jets are addressed.

Hussain, Fazle; Husain, Hyder S.

1989-01-01

420

Critical condition for the transformation from Taylor cone to cone-jet  

NASA Astrophysics Data System (ADS)

An energy method is proposed to investigate the critical transformation condition from a Taylor cone to a cone-jet. Based on the kinetic theorem, the system power allocation and the electrohydrodynamics stability are discussed. The numerical results indicate that the energy of the liquid cone tip experiences a maximum value during the transformation. With the proposed jetting energy, we give the critical transformation condition under which the derivative of jetting energy with respect to the surface area is greater than or equal to the energy required to form a unit of new liquid surface.

Wei, Cheng; Gang, Tie-Qiang; Chen, Li-Jie; Zhao, Yang

2014-06-01

421

Microbicidal activities of low frequency atmospheric pressure plasma jets on oral pathogens.  

PubMed

Research using low frequency atmospheric pressure plasma jets (LF jet) is becoming increasingly more common. We carried out experiments to evaluate the sterilizing effects of this technology on oral pathogenic microorganisms (S.mutans, C.albicans and E. faecalis) and to determine its potential for clinical application. We performed the direct exposure test on a solid surface, indirect exposure test on a liquid phase, and ROS (reactive oxygen species) inhibitory test. The results showed the LF jet had microbicidal effects on oral pathogens, and that the ROS influenced this sterilization effect. The experiments of this study revealed that LF jet had a sterilizing effect on oral pathogenic microorganisms present in both the solid and liquid phases. The sterilizing mechanism was considered to be related to the effect of superoxide anion radicals. These results indicate that LF jets may represent a novel technology that can be applied to the field of clinical dentistry. PMID:21597211

Yamazaki, Hiromitsu; Ohshima, Tomoko; Tsubota, Yuji; Yamaguchi, Hiroyasu; Jayawardena, Jayanetti Asiri; Nishimura, Yasushi

2011-01-01

422

Renewable jet fuel.  

PubMed

Novel strategies for sustainable replacement of finite fossil fuels are intensely pursued in fundamental research, applied science and industry. In the case of jet fuels used in gas-turbine engine aircrafts, the production and use of synthetic bio-derived kerosenes are advancing rapidly. Microbial biotechnology could potentially also be used to complement the renewable production of jet fuel, as demonstrated by the production of bioethanol and biodiesel for piston engine vehicles. Engineered microbial biosynthesis of medium chain length alkanes, which constitute the major fraction of petroleum-based jet fuels, was recently demonstrated. Although efficiencies currently are far from that needed for commercial application, this discovery has spurred research towards future production platforms using both fermentative and direct photobiological routes. PMID:24679258

Kallio, Pauli; Pásztor, András; Akhtar, M Kalim; Jones, Patrik R

2014-04-01

423

Liquid filament instability due to stretch-induced phase separation in polymer solutions: Liquid filament instability.  

PubMed

The instability in a jet of a viscoelastic semidilute entangled polymer solution under high stretching is discussed. Initially the jet is stable due to solution elasticity stopping the fluctuation growth. The modeling shows that a jet stretching results in a radial gradient in the polymer distribution: the polymer is concentrated in the jet centre, whereas the solvent is remaining near the surface. This viscous liquid shell demonstrates Raleigh-type instability resulting in the formation of individual droplets on the oriented filament. All process stages were observed experimentally. PMID:24566664

Kulichikhin, V G; Malkin, Al Ya; Semakov, Al V; Skvortsov, I Yu; Arinstein, A

2014-02-01

424

Jet Shockwaves Produce Gamma Rays  

NASA Video Gallery

Theorists believe that GRB jets produce gamma rays by two processes involving shock waves. Shells of material within the jet move at different speeds and collide, generating internal shock waves th...

425

Optical Measurements of Jet Atomization.  

National Technical Information Service (NTIS)

Experimental techniques for the investigation of very rapid running transient processes of jet formation and jet atomization are described. By application of a conventional nozzle for diesel engines it was possible to observe in transmitted light the expa...

H. Wiegand K. Wanders

1982-01-01

426

Numerical simulation of operation processes in the combustion chamber and gas generator of oxygen-methane liquid rocket engine  

NASA Astrophysics Data System (ADS)

The results of numerical simulations of processes in gas generators and combustion chambers operating on oxygen and methane are presented. Specific features of mixing, evaporation, and combustion of propellants have been investigated. The degree of combustion completeness in chambers with three types of injectors - coaxial-jet gas-liquid, liquid-liquid monopropellant, and bipropellant impinging-jets injectors - has been estimated.

Kalmykov, G. P.; Larionov, A. A.; Sidlerov, D. A.; Yanchilin, L. A.

2009-09-01

427

Liquid Impact Erosion Mechanisms in Transparent Materials.  

National Technical Information Service (NTIS)

a study has been made of damage mechanisms caused by liquid drop impact on various infra-red transparent solids. Techniques are described for producing liquid jets which simulate the damage produced by impact with spherical drops. Advantages of this appro...

J. E. Field M. J. Matthewson S. Zwaag

1979-01-01

428

Experimental study of underwater rock drilling using a pulsed Ho:YAG laser-induced jets  

NASA Astrophysics Data System (ADS)

This paper is primarily an assessment of laser-induced water jets for boring rock surfaces. It also reports the result of preliminary experiments of pulsed Ho:YAG laser-induced jets applied to drill a submerged rock specimen. The irradiation of pulsed Ho:YAG laser beams at 3 Hz inside a thin metal tube produces intermittent water vapor bubbles which result in liquid jet discharge from the exit of the metal tube. The laser-induced water jets are visualized by shadowgraphs and images are recorded by a high-speed digital video camera. High stagnation pressures were eventually generated by the jet impingements. Simultaneously shock waves of about 22.7 MPa were generated at bubble collapse, which effectively cracked the surface of the rock specimens. Repeated exposures of these laser-induced jets against submerged rock specimens have a potential to practically bore holes on rock surfaces.

Ohtani, K.; Numata, D.; Takayama, K.; Kobayashi, T.; Okatsu, K.

2009-10-01

429

Visualization of coherent structures in turbulent subsonic jet using planar laser induced fluorescence of acetone  

NASA Astrophysics Data System (ADS)

In this paper, we present the molecular density distribution measurement in turbulent nitrogen jet (Re ? 3×103), using acetone as molecular tracer. The tracer was seeded in the nitrogen jet by purging through the liquid acetone at ambient temperature. Planar laser sheet of 266 nm wavelength from frequency quadrupled, Q-switched, Nd:YAG laser was used as an excitation source. Emitted fluorescence images of jet flow field were recorded on CMOS camera. The dependence of planar laser induced fluorescence (PLIF) intensity on acetone vapor density was used to convert PLIF image of nitrogen jet into the density image on pixel-by-pixel basis. Instantaneous quantitative density image of nitrogen jet, seeded with acetone, was obtained. The arrowhead-shaped coherent turbulent structures were observed in the present work. It was found that coherent structures were non-overlapping with separate boundaries. Breaking of coherent structures into turbulence was clearly observed above four times jet width.

Shelar, Vikas M.; Hegde, Gopalkrishna M.; Umesh, Govindarao; Jagadeesh, Gopalan; Reddy, K. P. J.

2013-06-01

430

Heavy quark fragmenting jet functions  

NASA Astrophysics Data System (ADS)

Heavy quark fragmenting jet functions describe the fragmentation of a parton into a jet containing a heavy quark, carrying a fraction of the jet momentum. They are two-scale objects, sensitive to the heavy quark mass, m Q , and to a jet resolution variable, ? N .We discuss how cross sections for heavy flavor production at high transverse momentum can be expressed in terms of heavy quark fragmenting jet functions, and how the properties of these functions can be used to achieve a simultaneous resummation of logarithms of the jet resolution variable, and logarithms of the quark mass. We calculate the heavy quark fragmenting jet function at , and the gluon and light quark fragmenting jet functions into a heavy quark, and at . We verify that, in the limit in which the jet invariant mass is much larger than m Q , the logarithmic dependence of the fragmenting jet functions on the quark mass is reproduced by the heavy quark fragmentation functions. The fragmenting jet functions can thus be written as convolutions of the fragmentation functions with the matching coefficients , which depend only on dynamics at the jet scale. We reproduce the known matching coefficients at , and we obtain the expressions of the coefficients and at . Our calculation provides all the perturbative ingredients for the simultaneous resummation of logarithms of m Q and ? N .

Bauer, Christian W.; Mereghetti, Emanuele

2014-04-01

431

Jet Noise Research at NASA  

NASA Technical Reports Server (NTRS)

A presentation outlining current jet noise work at NASA was given at the NAVAIR Noise Workshop. Jet noise tasks in the Supersonics project of the Fundamental Aeronautics program were highlighted. The presentation gave an overview of developing jet noise reduction technologies and noise prediction capabilities. Advanced flow and noise diagnostic tools were also presented.

Henderson, Brenda

2008-01-01

432

Air admixture to exhaust jets  

NASA Technical Reports Server (NTRS)

The problem of thrust increase by air admixture to exhaust jets of rockets, turbojet, ram- and pulse-jet engines is investigated theoretically. The optimum ratio of mixing chamber pressure to ambient pressure and speed range for thrust increase due to air admixture is determined for each type of jet engine.

Sanger, Eugen

1953-01-01

433

Multi-jets formation using laser forward transfer  

NASA Astrophysics Data System (ADS)

The dynamics of multi-jets formation in liquid films has been investigated using the laser-induced forward transfer (LIFT) technique. This technique allows the deposition of micrometer-sized droplets with a high spatial resolution from a donor substrate to a receiver substrate. The donor was a silver nanoparticles ink-coated substrate. The interaction of the laser pulse with the donor ink layer generates an expanding bubble in the liquid which propels a jet towards the receiver. Silver lines have already been printed by depositing overlapping droplets in a “low speed” process. In order to increase the throughput, it is necessary to decrease the time between the depositions of two droplets. By scanning the beam of a high repetition rate UV picosecond laser (343 nm; 30 ps; 500 kHz) with a galvanometric mirror, successive pulses are focused on the silver nanoparticles ink-coated donor substrate. The shape and dynamics of single jets and adjacent jets have been investigated by means of a time-resolved imaging technique. By varying the distance between the laser spots, different behaviours were observed and compared to the printed droplets. A spacing of 25 ?m between laser spots was found to generate both stable jets and well-controlled, reproducible droplets at high speed.

Biver, Emeric; Rapp, Ludovic; Alloncle, Anne-Patricia; Delaporte, Philippe

2014-05-01

434

Jet Screech Noise Computation  

NASA Technical Reports Server (NTRS)

The near-field screech-tone noise of a typical underexpanded circular jet issuing from a sonic nozzle is simulated numerically. The self-sustained feedback loop is automatically established in the simulation. The computed shock-cell structure, acoustic wave length, screech tone frequencies, and sound pressure levels in the near field are in good agreement with existing experimental results.

Loh, Ching Y.; Hultgren, Lennart S.

2003-01-01

435

Bolometric diagnostics in JET  

SciTech Connect

Radiation losses from the JET plasma are measured (temporally and spatially resolved) with three pin-hole cameras which observe one poloidal plasma cross section from underneath (one vertical camera with 14 bolometers) and from the side (two horizontal cameras with 10 bolometers each). In addition, eight collimated single bolometers monitor toroidal symmetry of plasma emissivity. An improved metal resistor bolometer capable of surviving at least 5000 D--T pulses in JET is composed of two identical foils (4-..mu..m-thick gold absorber, 7.5-..mu..m-thick Kapton substrate, and 0.1-..mu..m-thick gold resistor), mounted one behind another in one housing. The rear foil serves as a reference bolometer in a bridge circuit. With an integration time constant of 20 ms a detection limit of 70 ..mu..W/cm/sup 2/ was measured in JET. Examples of measuring results in JET are presented: strong poloidal asymmetries of the radiation density as precursor signals of a density limit disruption and the formation of a poloidally symmetric, cold plasma mantle before a disruption.

Mast, K.F.; Krause, H.; Behringer, K.; Bulliard, A.; Magyar, G.

1985-05-01

436

The turbulent exponential jet  

Microsoft Academic Search

A new, self-similar, turbulent jet flow is postulated in which the global vorticity (O mega) is a constant following any vortex. In contrast, conventional self-similar flows all exhibit Omega inversely proportional to the vortex age. In order for the newly postulated flow to exist, the nozzle exit speed must increase exponentially with time. It is shown that this circumstance may

Robert Breidenthal

1986-01-01

437

Control of jet engines  

Microsoft Academic Search

Feedback control has always been an essential part of jet engines because they operate at or near their mechanical or aerothermal limitations. In this paper, the basics of controlling an engine while satisfying numerous constraints will be reviewed. The emphasis will be on commercial engines though most of the material is also applicable to military engines. In the first part,

H Austin Spang III; Harold Brown

1999-01-01

438

Spectroscopy with Supersonic Jets.  

ERIC Educational Resources Information Center

Discusses a new technique that enables spectroscopists to study gas phase molecules at temperatures below 1 K, without traditional cryogenic apparatus. This technique uses supersonic jets as samples for gas molecular spectroscopy. Highlighted are points in the theory of supersonic flow which are important for applications in molecular…

Skinner, Anne R.; Chandler, Dean W.

1980-01-01

439

An advection-diffusion model for the dispersion in quasi two-dimensional steady turbulent jets  

NASA Astrophysics Data System (ADS)

The study of turbulent jets in relatively enclosed geometries is relevant to many chemical engineering processes. Predicting the concentration of chemical reactants in time and space requires a good understanding of the jet dynamics. We have considered experimentally and theoretically the behaviour of liquid jets in a quasi-Hele-Shaw cell, where the jets are constrained in a narrow gap whose width is two orders of magnitude smaller than the length-scales of the other two flow dimensions. In this configuration, the dynamics shown by the jets is very rich. Detailed examinations of instantaneous structures of the flow reveal a high-speed sinuous core at the centre of the jet and large vortical structures on each side, which we analyse quantitatively using a variety of techniques (particle image velocimetry and dye experiments). These structures have a large impact on the mixing and dispersion properties of the jet. We propose a one-dimensional advection-diffusion model to account for the vertical dispersion in the jet. The diffusion coefficient assumed in the model is based on our understanding of the large-scale structures of these jets. The model is solved analytically using a similarity form in the case of a finite-volume release of tracers in the jet. The theoretical predictions and the experimental measurements show very good agreement.

Landel, Julien R.; Caulfield, C. P.; Woods, Andrew W.

2011-11-01

440

Jet measurements at the LHC  

NASA Astrophysics Data System (ADS)

I will review the latest results from the heavy ion program on high-pT jet physics at the LHC. The high luminosity PbPb run at the LHC in 2012 has significantly extended the capability of studying high-pT rare processes produced in the heavy ion collisions. New results from ALICE, ATLAS and CMS experiments will be presented. This includes detailed precision measurements on dijet energy imbalance, jet shape and fragmentation pattern, jet nuclear modification factor, jet-track correlations, as well as path-length dependence of jet quenching.

Li, Wei

2012-10-01