Note: This page contains sample records for the topic plunging liquid jet from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Measurements of air entrainment by vertical plunging liquid jets  

Microsoft Academic Search

This paper addresses the issue of the air-entrainment process by a vertical plunging liquid jet. A non-dimensional physical\\u000a analysis, inspired by the literature on the stability of free jets submitted to an aerodynamic interaction, was developed\\u000a and yielded two correlation equations for the laminar and the turbulent plunging jets. These correlation equations allow the\\u000a volumetric flow rate of the air

M. El Hammoumi; J. L. Achard; L. Davoust

2002-01-01

2

Measurements of air entrainment by vertical plunging liquid jets  

NASA Astrophysics Data System (ADS)

This paper addresses the issue of the air-entrainment process by a vertical plunging liquid jet. A non-dimensional physical analysis, inspired by the literature on the stability of free jets submitted to an aerodynamic interaction, was developed and yielded two correlation equations for the laminar and the turbulent plunging jets. These correlation equations allow the volumetric flow rate of the air carryunder represented by the Weber number of entrainment Wen to be predicted. The plunging jets under consideration issued from circular tubes long enough to achieve a fully developed flow at the outlet. A sensitive technique based on a rising soap meniscus was developed to measure directly the volumetric flow rate of the air carryunder. Our data are compared with other experimental data available in the literature; they also stand as a possible database for future theoretical modelling.

El Hammoumi, M.; Achard, J. L.; Davoust, L.

3

Flow characteristics of gas–liquid two phase plunging jet absorber–gas holdup and bubble penetration depth  

Microsoft Academic Search

A gas-liquid two phase plunging jet is formed through a gas sucking type multi-jet ejector nozzle. In this study, the effects\\u000a of various conditions in the multi-jet ejector nozzle, the column diameter, and the liquid jet length on penetration depth\\u000a of air bubblesl\\u000a \\u000a B\\u000a and gas holdup hG in a gas-liquid two phase plunging jet absorber were studied experimentally. Consequently,

Mitsuharu Ide; Hiroki Uchiyama; Toshifumi Ishikura

1999-01-01

4

Air entrainment by a plunging liquid jet on a liquid pool  

NASA Astrophysics Data System (ADS)

When a liquid jet impinges on liquid pool, with a velocity higher than a critical velocity, a thin air film is entrained by the jet. The thickness ha of the air film, and thus the air mass entrained by the jet, is a function of its radius a and velocity U. This function, for the realistic small values of the capillary number ? = ?a U/? << 1 (based on the air viscosity ?a and surface tension ?) turns out to be of the form h_a/a = F(a/a_c, ?), where a_c=? ?/?l g is the capillary length (based on the acceleration of gravity and liquid density ?_l). An analysis similar to the analysis of Levish and Landau, for the entrainment of liquid by a plate moving out of a liquid pool, shows that the dependence of h_a/a on ? is of the form h_a/a = ?^2/3f(a/a_c), where f is of order unity for a/ac << 1 and f ? a_c/a for large values of a_c/a

Liñan, Amable; Lasheras, Juan C.

1999-11-01

5

Distinguishing features of shallow angle plunging jets  

NASA Astrophysics Data System (ADS)

Numerical simulations employing an algebraic volume-of-fluid methodology are used to study the air entrainment characteristics of a water jet plunging into a quiescent water pool at angles ranging from ? = 10° to ? = 90° measured from the horizontal. Our previous study of shallow angled jets [S. S. Deshpande, M. F. Trujillo, X. Wu, and G. L. Chahine, ``Computational and experimental characterization of a liquid jet plunging into a quiescent pool at shallow inclination,'' Int. J. Heat Fluid Flow 34, 1-14 (2012)] revealed the existence of a clearly discernible frequency of ingestion of large air cavities. This is in contrast with chaotic entrainment of small air pockets reported in the literature in case of steeper or vertically plunging jets. In the present work, the differences are addressed by first quantifying the cavity size and entrained air volumes for different impingement angles. The results support the expected trend - reduction in cavity size (D43) as ? is increased. Time histories of cavity volumes in the vicinity of the impingement region confirm the visual observations pertaining to a near-periodic ingestion of large air volumes for shallow jets (10°, 12°), and also show that such cavities are not formed for steep or vertical jets. Each large cavity (defined as Dc/Dj >~ 3) exists in close association with a stagnation point flow. A local mass and momentum balance shows that the high stagnation pressure causes a radial redirection of the jet, resulting in a flow that resembles the initial impact of a jet on the pool. In fact, for these large cavities, their speed matches closely Uimpact/2, which coincides with initial cavity propagation for sufficiently high Froude numbers. Furthermore, it is shown that the approximate periodicity of air entrainment scales linearly with Froude number. This finding is confirmed by a number of simulations at ? = 12°. Qualitatively, for steeper jets, such large stagnation pressure region does not exist, and the deflection of the entire incoming jet is non-existent. In fact, for ? = 25°, 45°, 90°, the jet penetrates the pool nearly undisturbed and consequently large cavities are not formed.

Deshpande, Suraj S.; Trujillo, Mario F.

2013-08-01

6

Modeling air entrainment in plunging jet using 3DYNAFS  

Microsoft Academic Search

As the liquid jet plunges into a free surface, significant air is entrained into the water and forms air pockets. These air pockets eventually break up into small bubbles, which travel downstream to form a bubbly wake. To better understand the underlying flow physics involved in the bubble entrainment, in the linked videos, air entrainment due to a water jet

Chao-Tsung Hsiao; Jingsen Ma; Xiongjun Wu; Georges L. Chahine

2011-01-01

7

Air entrainment by a viscous jet plunging into a bath.  

PubMed

A liquid jet plunging into a container of liquid often entrains a thin film of air with it, producing bubbles. This bubble production is detrimental to many industrial processes, such as filling a container with a molten glass or polymer, or in coating processes. Conversely, in making a foam, one uses this effect; hence it is important to control the rate of bubble production. Here, we measure the amount of air entrained by a viscous jet over a wide range of parameters and explain the phenomenon theoretically. Simple scaling arguments are shown to predict entrainment rates over 4 orders of magnitude in the dimensionless jet speed. PMID:15697900

Lorenceau, Elise; Quéré, David; Eggers, Jens

2004-12-13

8

Air Entrainment by a Viscous Jet Plunging into a Bath  

NASA Astrophysics Data System (ADS)

A liquid jet plunging into a container of liquid often entrains a thin film of air with it, producing bubbles. This bubble production is detrimental to many industrial processes, such as filling a container with a molten glass or polymer, or in coating processes. Conversely, in making a foam, one uses this effect; hence it is important to control the rate of bubble production. Here, we measure the amount of air entrained by a viscous jet over a wide range of parameters and explain the phenomenon theoretically. Simple scaling arguments are shown to predict entrainment rates over 4 orders of magnitude in the dimensionless jet speed.

Lorenceau, Élise; Quéré, David; Eggers, Jens

2004-12-01

9

Air Entrainment by a Translating Plunging Jet  

NASA Astrophysics Data System (ADS)

Experiments have been performed to determine the inception boundary for air entrainment by a vertical laminar plunging jet as it is translated above the surface of a quiescent pool. Parameters for the experiment include the translation velocity of the jet, the normal impact velocity of the jet, and the jet impact diameter. For stationary non-entraining jets with diameters ranging from .3 cm to 1.2 cm and impact velocities of 71 to 368 cm/s, the critical translational velocity for entrainment is found to vary in the range from 30 to 50 cm/s. Imaging analysis of the process shows that the air is entrained from an instability which develops in the low-speed recirculation zone immediately downstream of the jet impact site, and initially occurs through the formation of minute intermittent bubbles. At larger translational velocities, larger bubbles are entrained intermittently until a state of continual vigorous air entrainment is reached. Initial tests indicate that the intermittent, small-bubble entainment boundary follows a Froude scaling based on the translation velocity of jet, and is largely independent of the jet normal impact velocity.

Kiger, Ken

1999-11-01

10

Experiments with plunging cylinder liquid piston Stirling engines  

Microsoft Academic Search

Plunging cylinder liquid piston Stirling engines with flow restrictive seals were tested at atmospheric mean pressure and low temperatures. Two method of fluid level control within the plunging cylinders were investigated, and a higher temperature hot oil engine was operated. An engine was built with 5.75 in internal diameter cylinders with 22 in strokes, to be run in either a

Peter Tailer

1989-01-01

11

Incipient air entrainment in a translating axisymmetric plunging laminar jet  

NASA Astrophysics Data System (ADS)

Air entrainment due to a translating axisymmetric laminar water jet plunging into an otherwise quiescent pool of water was studied experimentally. The jet impact diameter, Dj, and velocity, Vj, ranged from 0.33 to 1.21 cm and 104 to 365 cm/s, respectively. For all of these jet flow conditions, the water surface around the jet impact site of the stationary jet is smooth and no air is entrained. When the jet is moving horizontally with velocity Vt, a depression of the free surface forms directly downstream of the jet. In any set of experiments with constant Vj and Dj, as Vt is increased, the depth and streamwise length of this depression increases and a cusp forms at the bottom of its upstream edge. Air entrainment first occurs in the form of discrete small bubbles with diameters of about 0.05 cm that are injected from the cusp when the Froude number (Fr=Vt/gDj, where g is the acceleration of gravity) exceeds a critical value of about 1.4 for Vj/Vt>5. At higher values of Vt, a separate mode of entrainment occurs where large pockets of air are injected from the cusp into the flow in the form of intermittent bursts. At still higher values of Vt, the high-entrainment-rate condition occurs continuously. High-speed flow visualization movies of the entrainment process show that in all entrainment regimes, the bubbles enter the water when vortices from the jet shear layer pass over the leading-edge cusp of the depression and that these bubbles are initially trapped within the vortices. The boundaries between the three entrainment regimes are determined and presented on a plot of Froude number versus velocity ratio (Vj/Vt).

Chirichella, D.; Gomez Ledesma, R.; Kiger, K. T.; Duncan, J. H.

2002-02-01

12

Plunging cylinder liquid piston Stirling engine  

SciTech Connect

A Stirling engine is described comprising, in combination, cylinders having tops and open lower ends, tanks containing hot and cold fluid, with a means plunging the cylinders out of phase into the hot and cold fluid. There is at least one connecting tube providing a passage between the upper portions of the cylinders. A working gas provided in the upper portion of the cylinders and the connecting tube.

Tailer, P.L.; West, J.H.

1987-06-30

13

Onset of air entrainment in laminar plunging jets  

NASA Astrophysics Data System (ADS)

A cylindrical jet impacting perpendicularly on a free surface is known to entrain air above a critical velocity. The question of the determination of the onset of air entainment has received a large attention, and various correlations are proposed in the litterature (see the review by Bin, Chem. Eng. Sc.- 1993). For jets free of any surface roughness, extensive data have been correlated by Lin and Donnelly (A.I.Ch.E. J. - 1965) leading to a widely accepted onset criteria of the form We = 10 Re^0.74 where the Weber and Reynolds numbers are defined on the jet characteristics at impact. However, this correlation fails for viscosities below 25cSt or Re above 1200. In addition, it cannot be extended to planar liquid sheets. Here, we revisit the question of the onset of air entrainment, and in particular the effect of the liquid properties such as viscosity and surface tension. Experiments have been conducted for viscous liquids and over a wide range of jet diameters. We propose a model which accounts both for the depression induced by the entrained flow field and for the viscous stresses at the interface generated by the acceleration of the liquid along the free surface. The onset of air entrainment expresses as a critical capillary number Ca versus the Morton number Mo =?^3 g ?^4 / ?^3 (one has Mo = (Ca/Rec)^2, where Rec is the Reynolds number based on the capillary length) and the ratio a/R of the capillary length to the jet radius. In the limit of large (respectivelly small) Morton numbers, Ca behaves as Mo^1/6 (respectivelly Mo^1/4) in agreement with the experiments. The dependency of Ca versus a/R will also be discussed.

Cartellier, A.; Lasheras, J. C.

1999-11-01

14

Field manual for plunging water jet use in oil spill cleanup. Final report Sep 82Jul 83  

Microsoft Academic Search

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 planning personnel on the principles of plunging water jet operation, rapid fabrication of the equipment (from readily available

1984-01-01

15

Air Entrainment Mechanism by a Translating Axisymmetric Plunging Jet  

NASA Astrophysics Data System (ADS)

Air entrainment induced by an axisymmetric, vertical, horizontally translating water jet as it impinges onto the free surface of a quiescent pool was studied experimentally using high-speed imaging techniques. A cavity is observed to form immediately downstream of the jet impact point and air is entrained from the cusp formed at the bottom of the leading edge of the cavity. Observations with the jet marked by small particles revealed the presence of vortices on the shear layer formed around the submerged jet. These vortices induce undulations on the upstream edge of the air cavity and seem to play an important role in the air entrainment mechanism. In particular, the entrainment occurs when the air cavity cusp reaches a critical depth where the vortices are strong enough to tear bubbles from the water/air interface.

Gomez-Ledesma, R.; Chirihella, D.; Duncan, J.; Kiger, K.

2000-11-01

16

The hydraulic bump: The surface signature of a plunging jet  

NASA Astrophysics Data System (ADS)

When a falling jet of fluid strikes a horizontal fluid layer, a hydraulic jump arises downstream of the point of impact, provided a critical flow rate is exceeded. We here examine a phenomenon that arises below this jump threshold, a circular deflection of relatively small amplitude on the free surface that we call the hydraulic bump. The form of the circular bump can be simply understood in terms of the underlying vortex structure and its height simply deduced with Bernoulli arguments. As the incoming flux increases, a breaking of axial symmetry leads to polygonal hydraulic bumps. The relation between this polygonal instability and that arising in the hydraulic jump is discussed. The coexistence of hydraulic jumps and bumps can give rise to striking nested structures with polygonal jumps bound within polygonal bumps. The absence of a pronounced surface signature on the hydraulic bump indicates the dominant influence of the subsurface vorticity on its instability.

Labousse, M.; Bush, J. W. M.

2013-09-01

17

The role of surface disturbances in the entrainment of bubbles by a liquid jet  

Microsoft Academic Search

In this paper, air entrainment by a liquid jet is studied. The size of bubbles entrained by jets plunging into a liquid can be consistently decreased to the 50 100 [mu]m range, and their number increased in a highly controllable fashion, by surrounding a mm-size jet by a hollow cap with a slightly larger inner diameter. When the right amount

Hasan N. Oguz

1998-01-01

18

Depth of penetration of bubbles entrained by a plunging water jet  

Microsoft Academic Search

A model is proposed to predict the depth of penetration of the air bubbles entrained by a round water jet impacting into a flat, liquid pool. This depth is shown to be determined only by the initial jet momentum and by the non-monotonic nature of the bubble terminal velocities as a function of their size. The model is shown to

Christophe Clanet; Juan C. Lasheras

1997-01-01

19

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

20

Cryopreservation of human ovarian tissue by direct plunging into liquid nitrogen  

Microsoft Academic Search

Aim: To establish a prospective direction for further development of the protocol for cryopreservation of ovarian tissue by direct plunging into liquid nitrogen. Materials and methods: Human ovarian biopsies from 20 patients (cut in ?0.5mm3 pieces) were exposed to: 40% ethylene glycol+0.35M sucrose+5% egg yolk; 40% ethylene glycol+18% Ficoll-70+0.35M sucrose; 20% ethylene glycol+20% dimethyl sulphoxide. Cryopreservation of pieces was accomplished

E Isachenko; V Isachenko; G Rahimi; F Nawroth

2003-01-01

21

Bouncing of a Jet off a Newtonian Liquid Surface  

NASA Astrophysics Data System (ADS)

A viscous liquid stream plunging toward a horizontally moving bath of the same liquid can bounce off the surface without mixing with the bath's fluid. A thin layer of air separates the jet and the bath. The non-coalescing jet ramps off an indentation that it makes in the bath's surface. The jet then moves in a roughly parabolic flight until it hits the translating surface again, where it may bounce a second time. Similar rebounding phenomena, such as the Kaye effect, have been observed in non-Newtonian fluids. However, we report the first observations of a bouncing Newtonian liquid jet. We observe the bouncing jet for many different liquids, including silicone oil. The bouncing jet is stable for a large range of parameters, including the oil's viscosity (50 to 520 mPa s), the jet's radius (0.05 to 0.12 cm), the jet's velocity at impact (40 to 170 cm/s, corresponding to nozzle heights 1.7 to 14 cm), and the bath's horizontal velocity (1 to 35 cm/s). The bouncing jet involves an interplay of viscous, inertial, surface, and gravitational forces. By initiating the jet in different ways, up to four stable configurations have been observed for the same experimental conditions. A video entry into the Gallery of Fluid Motion features this research.

Thrasher, Matthew; Jung, Sunghwan; Swinney, Harry L.

2006-11-01

22

Plunging ranula.  

PubMed

Plunging ranulas are rare cystic masses in the neck that are mucous retention pseudocysts from an obstructed sublingual gland. They "plunge" by extending inferiorly beyond the free edge of the mylohyoid muscle, or through a dehiscence of the muscle itself, to enter the submandibular space. Imaging demonstrates a simple cystic lesion in the characteristic location and can be used to delineate relevant surgical anatomy. Surgical excision of the collection and the involved sublingual gland is performed for definitive treatment. We present a case of plunging ranula in a 44 year old female who presented with a painless, slowly enlarged neck mass. Plunging ranulas should be considered in the differential diagnosis of cystic neck masses, specifically when seen extending over, or through, the mylohyoid muscle. PMID:22470797

Kalra, Vivek; Mirza, Khurram; Malhotra, Ajay

2011-06-01

23

Transient gas jets into liquids  

NASA Astrophysics Data System (ADS)

An experimental investigation of the development of high velocity, impulsively initiated gas jets into liquid was conducted in an effort to understand some of the physical processes that occur for a jet of very light fluid into a dense ambient atmosphere. Four gases, refrigerants 12 and 22, nitrogen, and helium were injected into water at nozzle exit Mach numbers from 1.0 to 2.2.The study showed that a gas jet into water develops in at least three stages: startup, transition, and global steady state. The startup is characterized by bubble growth; the growth rate is well predicted by classical bubble-growth theory. Jet transition is marked by axially directed flow, which penetrates through the startup bubble and which forms a cylindrical protrusion along the axis of symmetry. A combination of strong recirculating flow and liquid entrainment causes the startup bubble to deflate and to lift off and move downstream. In the steady state, instantaneous photographs show small-scale fluctuations of the jet boundary, but time-averaged photographs show the expected conical spreading of the steady jet; the measured spreading angles range from 18-25 degrees.However, the most significant finding of this study is that under some conditions, the gas jet into liquid never reaches the global steady state. Instead, the jet boundary exhibits chugging: large nonlinear oscillations which lead to irregular collapses of the gas column followed by explosive outward bursts of gas. The unsteadiness observed is much more violent than the familiar fluctuations typical of constant-density jets. The length scale of the motion is generally on the order of several jet diameters; the time scale is on the order of the period for bubble collapse.It was found that the amplitude and frequency of chugging are strongly dependent on the ratio of the liquid density to the gas density, the jet Mach number, and the operating pressure ratio. The conditions under which unsteadiness occurs were determined experimentally. In particular, a quantitative measure of jet susceptibility to unsteadiness has been established. Steady jets can be achieved in two ways: by being discharged from deLaval nozzles (increasing the exit Mach number) or by being overpressured.The unsteady behavior is modeled as the collapse of a bubble in liquid; comparisons of collapse times show good agreement. A mechanism for the unsteadiness is discussed. It is proposed that the chugging is the response of the jet boundary to a pressure difference between the jet and surrounding liquid, which arises as the result of the rapid expansion of a light fluid into a dense ambient atmosphere. The flow is shown to be similar to the discharge of a gas from a nozzle into a channel of larger cross section. An upper limit to the pressure difference is determined based on estimates of the minimum base pressure for such channel flows; a lower limit is established for the collapse time. All experimental values are within the bounds. The derived values indicate that the pressure differences between the jet and liquid may be more than 90 percent of the ambient pressure.

Lin, Jane Ming-Chin

24

Cavitation bubble behavior inside a liquid jet  

Microsoft Academic Search

The growth and collapse of laser-induced vapor cavities inside axisymmetric free-falling liquid water jets have been studied. Bubbles of different size are generated at various distances from the jet axis and the effects on the jet interface are recorded by means of ultrafast cinematography. The configuration is characterized by two dimensionless parameters: the bubble to jet diameter ratio delta and

Etienne Robert; Jacques Lettry; Mohamed Farhat; Peter A. Monkewitz; François Avellan

2007-01-01

25

Cavitation bubble behavior inside a liquid jet  

NASA Astrophysics Data System (ADS)

The growth and collapse of laser-induced vapor cavities inside axisymmetric free-falling liquid water jets have been studied. Bubbles of different size are generated at various distances from the jet axis and the effects on the jet interface are recorded by means of ultrafast cinematography. The configuration is characterized by two dimensionless parameters: the bubble to jet diameter ratio ? and the eccentricity coefficient ? defined as the radius of bubble generation divided by the jet radius. For high ? and V, microjets and droplets are ejected from the liquid jet at speeds exceeding 100 m/s. The observed jet fragmentation shows similarities with experiments conducted on a liquid mercury jet hit by a pulsed proton beam, a candidate configuration for future accelerator based facilities.

Robert, Etienne; Lettry, Jacques; Farhat, Mohamed; Monkewitz, Peter A.; Avellan, François

2007-06-01

26

The role of surface disturbances in the entrainment of bubbles by a liquid jet  

NASA Astrophysics Data System (ADS)

In this paper, air entrainment by a liquid jet is studied. The size of bubbles entrained by jets plunging into a liquid can be consistently decreased to the 50 100 [mu]m range, and their number increased in a highly controllable fashion, by surrounding a mm-size jet by a hollow cap with a slightly larger inner diameter. When the right amount of air is supplied to the cap, small air bubbles detach from a steady annular cavity that forms around the jet and are entrained into the liquid. The fluid mechanical principles underlying this interesting and useful effect are investigated experimentally and theoretically in this paper. It is shown that a key aspect of the process is the jet surface roughness, which is studied quantitatively and explained in terms of the boundary layer instability inside the nozzle. The maximum bubble size is found to be nearly equal to one quarter of the wavelength of the jet surface disturbances, consistent with a breakup process of relatively large air pockets around the jet, as suggested by close-up pictures. The average bubble size downstream of the cap increases proportionally to the air to water flow ratio. Boundary integral simulations of the air pocket formation are carried out. The results are found to be useful in explaining important characteristics of the experiment such as the threshold for entrainment and cavity size.

Oguz, Hasan N.

1998-10-01

27

Air entrainment by a liquid jet  

NASA Astrophysics Data System (ADS)

We describe experimental work on air entrainment by a liquid jet impacting a bath of the same viscous liquid. We show that the entrainment velocity is shifted due to the widening out of the jet before its impact. The apparent entrainment threshold is determined quantitatively. The thickness of the entrained air film is measured and described by a Landau and Levich model. We also study the impact of a fibre coated with oil on a bath of the same oil. This modified setup allows a simpler analysis of the results and is a good experimental support to the jet problem.

Reyssat, Etienne; Quere, David

2007-11-01

28

Liquid transverse jets in compressible crossflows  

NASA Astrophysics Data System (ADS)

A numerical/analytical model is described which predicts the behavior of the non-reacting and the reacting liquid jet in a compressible flow (both supersonic and subsonic). The compressible flowfield about the elliptical jet cross-section is solved at various locations along the jet trajectory by analytical means for M infinity less than or equal to 0.3 and numerical means for M infinity greater than 0.3. External and internal boundary layers along the jet cross-section is calculated and used to determine the jet trajectory by a balance between aerodynamic drag and centripetal forces resulting from jet deflection. The mass loss due to boundary layer shedding and due to evaporation are calculated and incorporated into the trajectory calculation and comparison with experimental observations is made. For supersonic crossflows, the bow shock shape is predicted as well. The presence of a diffusion flame for M infinity less than or equal to 0.3 is also studied, and its effect on mass loss from the fuel jet and on the trajectory shape is explored.

Nguyen, Trinh The

29

Calculation of pulsating liquid free jets  

NASA Astrophysics Data System (ADS)

A liquid free jet with strong velocity modulation is treated theoretically. The special shape of the jet is described by a simple analytical model based on kinematic effects. The interaction between different flow particles which start consecutively from the nozzle exit is neglected. This solution shows singular points and triple valued regions. In practice, these are regions where strong interaction of flow particles of different velocities can no longer be neglected. In the theoretical model, these regions are contracted to single points where a velocity jump occurs in the jet, and a secondary flow starts in lateral direction. The variation of the velocity in the jet causes the longitudinal velocity of different flow elements to be different. This is the reason for a bell like shape being formed.

Grabitz, Georg

1990-07-01

30

Vitrification of pure liquid water by high pressure jet freezing  

Microsoft Academic Search

The vitrification of pure liquid water by projecting a thin jet of liquid water at high speed into a liquid cryomedium is reported. The influence of the experimental parameters on the cooling rate and the devitrification of the jet-frozen vitrified material have been investigated. A structural difference between vitrified liquid water and amorphous solid water prepared from the vapour phase

Erwin Mayer; Peter Brüggeller

1982-01-01

31

Compound liquid jets at low Reynolds numbers  

Microsoft Academic Search

Asymptotic methods based on the slenderness ratio are used to obtain the leading-order equations which govern the fluid dynamics of axisymmetric, isothermal, Newtonian, compound liquid jets such as those employed in the manufacture of textile fibres, composite fibres and optical fibres, at low Reynolds numbers. It is shown that the leading-order equations are one-dimensional, and analytical solutions are obtained for

J. I Ramos

2002-01-01

32

Size limits the formation of liquid jets during bubble bursting  

PubMed Central

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 number of such bubbles in sea water. Here we show that jet formation is inhibited by bubble size; a jet is not formed during bursting for bubbles smaller than a critical size. Using ultrafast X-ray and optical imaging methods, we build a phase diagram for jetting and the absence of jetting. Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. The coalescence mechanism for bubble bursting may be useful in preventing jet formation in industry and improving climate models concerning aerosol production.

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

2011-01-01

33

Recurrent plunging ranula  

PubMed Central

We report two cases of plunging ranula, which had recurred after marsupialization. Both were successfully treated by removal of the ipsilateral sublingual gland. A brief review of the literature regarding the treatment options is presented.

Arunachalam, Pavai; Priyadharshini, Nithya

2010-01-01

34

Dropsize correlation for cryogenic liquid-jet atomization  

NASA Astrophysics Data System (ADS)

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.

1990-07-01

35

Dropsize Correlation for Cryogenic Liquid-Jet Atomization.  

National Technical Information Service (NTIS)

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. Nit...

R. D. Ingebo

1990-01-01

36

A hybrid model for simulating velocity field of a river with complex geometry plunged by multiple jets 1 1 Project supported by the Trans-century Training Programme Foundation for the Talents by the State Ministry of Education of China and the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China  

Microsoft Academic Search

A hybrid model that combines both physical and numerical models was employed to simulate the velocity field in a river area in complex geometry with multiple plunging jets. The simulation was based on experiments concerning energy dissipation and scour prevention at the Xiluodu Hydropower Station on the Yangtze River. The calculated results indicate that the complex geometry of the river

Lian-xia LI; Hua-sheng LIAO; Tian-xiang LI

2006-01-01

37

Analysis of interaction phenomena between liquid jets and materials [preprint  

SciTech Connect

The interaction phenomena of high-velocity liquid jets impinging on a material surface have been investigated theoretically and experimentally to understand the physics of material removal by jet-machining processes. Experiments were performed to delineate conditions under which liquid jet impacts will cause mass removal and to determine optimum jet-cutting conditions. Theoretical analyses have also been carried out to study the effects of multiple jet-droplet impacts on a target surface as a material deformation mechanism. The calculated target response and spallation behavior following droplet impacts and their physical implications are also discussed.

Kang, S-W.; Reitter, T.; Carlson, G.

1995-04-01

38

GAS-LIQUID MASS TRANSFER IN JET BUBBLE COLUMN  

Microsoft Academic Search

The jet bubble column consists of a conical entrance section which expands to a cylindrical column. Gas and liquid are co-currently introduced at the bottom of the column by a small diameter inlet pipe which acts like an ejector. The kinetic energy of the gas and liquid jet together with the conical geometry at the lower section of the column

JOSE A. SALAZAR; KEITH D. WISECARVER; Y. T. SHAH; BRUNO SOLARI

1993-01-01

39

Gas-Liquid Jets under Reduced Gravity Conditions.  

National Technical Information Service (NTIS)

Experimental drafts for the investigation of the behavior of gas-liquid jets under microgravity conditions and a conception of a facility to use inside the capsule of the drop tower Bremen are presented. Gas-liquid jets are very important subjects of flui...

O. Pamperin H. J. Rath

1992-01-01

40

The relaxation of liquid jet after isochoric heating  

Microsoft Academic Search

During isochoric heating by fast neutrons, a high pressure is instantaneously built up inside the falling liquid jets in a HYLIFE inertial confinement fusion reactor. The jets may break up as a consequence of negative pressure occurring during the flow transient in the period of depressurization. One important reason of the breakup, is the vaporization of the liquid inside the

Xiang M. Chen; V. E. Schrock

1989-01-01

41

Bouncing jet: A Newtonian liquid rebounding off a free surface  

NASA Astrophysics Data System (ADS)

We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g., the Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing phenomenon exhibits hysteresis and multiple steady states.

Thrasher, Matthew; Jung, Sunghwan; Pang, Yee Kwong; Chuu, Chih-Piao; Swinney, Harry L.

2007-11-01

42

Absolute to convective instability transition in charged liquid jets  

NASA Astrophysics Data System (ADS)

We show that the presence of electric charge at the interface of a capillary liquid jet plays a secondary role concerning the onset of an absolute or a convective instability in common operational conditions for cone-jet electrosprays, compared to other factors such as the convective velocity, jet diameter, surface tension ?, density ?, or viscosity ?. Thus, in most situations, the critical convective velocity (or its related dimensionless number, the critical Weber number Wecr) at the threshold between the dripping and the jetting regimes depends mainly on the viscosity of the fluid, scaled as a Reynolds number Re, and not so importantly on the electric forces at the interface of the jet. Accordingly, for any liquid, the classical curve of Leib and Goldstein [Phys. Fluids 29, 952 (1986)] for Wecr versus Re is accurate enough to explore the parametrical conditions where a steady cone-jet mode is to be expected, linked to the convectively unstable nature of the issued jet. However, at the limit of low Reynolds numbers, the stability behavior becomes strongly sensitive to the electrical conductivity of the liquid. Thus, a parametrical region where a charged capillary jet becomes strongly stabilized by the viscous damping against the destabilizing surface electrical forces is described in detail in this work. The ``unconditional jetting'' limit previously described for a capillary jet surrounded by a coflowing liquid [A. M. Gan~án-Calvo, Phys. Rev. E 78, 026304 (2008)] is here recovered in the absence of a coflowing fluid when ``frozen'' surface charges are present.

López-Herrera, José M.; Gañán-Calvo, Alfonso M.; Herrada, Miguel A.

2010-06-01

43

Turbulent noncondensing and condensing gas jets in liquids  

NASA Astrophysics Data System (ADS)

Gas injection into liquids is a fundamental multiphase flow which has several direct applications, e.g., stored chemical energy propulsion systems (SCEPS), direct-contact condensers, gas dissolution systems, reservoir destratification systems and nuclear-reactor pressure suppression systems. Stability of these flow is enhanced when an underexpanded jet is used; therefore, the interaction of supersonic wave structures with liquids in turbulent flow is also an issue. The objective of this phase of the study was to develop test apparatus relating to underexpanded air jets in air and turbulent subsonic gas jets in liquids. The air-jet-in-air apparatus was assembled and flow visualization tests were completed using continuous and spark Schlieren photography. Test apparatus for gas injection in liquids was assembled. Tests were also undertaken to study injector stability. Test results showed that jet instability for subsonic (adapted) flow could be controlled by placing a screen across the jet exit and controlling gas release at the surface or the bath (which can cause undesirable pressure fluctuations in the bath). For stable jets, the liquid/gas interface is continous near the jet exit and its position is influenced by the degree of underexpansion. A bubble cloud was observed near the interface, and it is also probable that a drop cloud in present as well. Analysis of this flow for subsonic jet exit conditions was implemented using the locally homogeneous flow approximation of multiphase flow.

Sun, T. Y.; Chuech, S. G.; Parthasarathy, R. N.; Faeth, G. M.

1985-08-01

44

Jet pinch-off in liquid-liquid systems with surface tension  

NASA Astrophysics Data System (ADS)

The breakup of an axisymmetric jet into drops in immiscible liquid-liquid systems is investigated numerically with a diffuse-interface method. The simulations are compared to the results of recent experiments. Pinchoff of a liquid/liquid jet has a wide variety of applications ranging from ink-jet printers to the flow of oil in lubricated pipeline. The diffuse-interface method smoothly deals with topological transitions such as breakup and reconnection.

Kim, Jun-Seok; Lowengrub, John; Longmire, Ellen

2002-11-01

45

Plunging ranula: a case report.  

PubMed

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. PMID:21991487

Gupta, Ambika; Karjodkar, F R

2010-09-08

46

Analysis of interaction phenomena between liquid jets and materials  

SciTech Connect

The interaction phenomena of high-velocity liquid jets impinging on a material surface have been investigated theoretically and experimentally to gain an understanding of the physical mechanisms involved in material removal by fluidjet machining processes. Experiments were performed to determine conditions under which the liquid jet impacting a solid material will cause material removal and also to delineate possible physical mechanisms of mass removal at optimum jet-cutting conditions. We have also carried out numerical simulations of jet-induced surface pressure rises and of the material deformation and spallation behavior due to multiple droplet impacts. Results obtained from the experiments and theoretical calculations and their physical implications are also discussed.

Kang, Sang-Wook; Reitter, T.; Carlson, G.

1995-02-01

47

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

Microsoft Academic Search

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

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

2011-01-01

48

ELECTROHYDRODYNAMIC ATOMIZATION IN THE CONE–JET MODE PHYSICAL MODELING OF THE LIQUID CONE AND JET  

Microsoft Academic Search

A physical model has been developed which is able to calculate the shape of the liquid cone and jet, the electric fields in and outside the cone, and the surface charge density at the liquid surface. The model also estimates the liquid velocity at the cone surface. The results of this cone-shape model fit well with experimental values with respect

R. P. A. Hartman; D. J. Brunner; D. M. A. Camelot; J. C. M. Marijnissen; B. Scarlett

1999-01-01

49

Secondary Breakup of Aerated Liquid Jets in Subsonic Crossflow (Postprint).  

National Technical Information Service (NTIS)

An experimental investigation of the secondary breakup of an aerated liquid jet in subsonic crossflow is described. The present test conditions were similar to those encountered in fuel injection in ramjet engines. Previous studies of spray structures of ...

B. Miller C. Carter K. Lin K. A. Sallam M. Bingabr

2008-01-01

50

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

51

Jet penetration and liquid splash in submerged gas injection  

Microsoft Academic Search

Jet penetration, bubble dispersion, and liquid splash were studied in the nitrogen-water system. Among the effects evaluated were those due to lance design, nozzle dimensions, gas driving pressure, and liquid density. In side-nozzle injection, penetration is found to increase with jet force number, N, given by the product of the gas driving pressure and the nozzle diameter. In top-submerged injection,

Basil U. N. Igwe; S. Ramachandran; J. C. Fulton

1973-01-01

52

Jet penetration and liquid splash in submerged gas injection  

Microsoft Academic Search

Jet penetration, bubble dispersion, and liquid splash were studied in the nitrogen-water system. Among the effects evaluated\\u000a were those due to lance design, nozzle dimensions, gas driving pressure, and liquid density. In side-nozzle injection, penetration\\u000a is found to increase with jet force number,N, given by the product of the gas driving pressure and the nozzle diameter. In top-submerged injection, horizontal

Basil U. N. Igwe; S. Ramachandran; J. C. Fulton

1973-01-01

53

Liquid flow focused by a gas: Jetting, dripping, and recirculation  

NASA Astrophysics Data System (ADS)

The liquid cone-jet mode can be produced upon stimulation by a coflowing gas sheath. Most applications deal with the jet breakup, leading to either of two droplet generation regimes: Jetting and dripping. The cone-jet flow pattern is explored by direct axisymmetric volume of fluid (VOF) numerical simulation; its evolution is studied as the liquid flow rate is increased around the jetting-dripping transition. As observed in other focused flows such as electrospraying cones upon steady thread emission, the flow displays a strong recirculating pattern within the conical meniscus; it is shown to play a role on the stability of the system, being a precursor to the onset of dripping. Close to the minimum liquid flow rate for steady jetting, the recirculation cell penetrates into the feed tube. Both the jet diameter and the size of the cell are accurately estimated by a simple theoretical model. In addition, the transition from jetting to dripping is numerically analyzed in detail in some illustrative cases, and compared, to good agreement, with a set of experiments.

Herrada, Miguel A.; Gañán-Calvo, Alfonso M.; Ojeda-Monge, Antonio; Bluth, Benjamin; Riesco-Chueca, Pascual

2008-09-01

54

Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas  

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 in 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 exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper presents the first obtained experimental results concerning the liquid gallium jet-plasma interaction. A stable jet has been obtained, which was not noticeably affected by the magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the power deposited on the jet has been evaluated at different radial locations and the surface temperature increase estimated.

Gomes, R. B.; Fernandes, H.; Silva, C.; Sarakovskis, A.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I.

2008-04-01

55

Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas  

SciTech Connect

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in 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 exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the interaction of a free flying, fully formed liquid gallium jet with the plasma. The interacting, 2.3 mm diameter, jet is generated by hydrostatic pressure and has a 2.5 m/s flow velocity. The liquid metal injector has been build to allow the positioning of the jet inside the tokamak chamber, within a 13 mm range. This paper presents the first obtained experimental results concerning the liquid gallium jet-plasma interaction. A stable jet has been obtained, which was not noticeably affected by the magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the power deposited on the jet has been evaluated at different radial locations and the surface temperature increase estimated.

Gomes, R. B.; Fernandes, H.; Silva, C.; Pereira, T.; Figueiredo, J.; Carvalho, B.; Soares, A.; Duarte, P.; Varandas, C. [Associacao EURATOM/IST, Centro de Fusao Nuclear, Av. Rovisco Pais, 1049-001 Lisboa, Porugal (Portugal); Sarakovskis, A.; Lielausis, O.; Klyukin, A.; Platacis, E.; Tale, I. [Association EURATOM/University of Latvia, Institute of Solid State Physics, 8 Kengaraga Str., LV-1063 Riga (Latvia)

2008-04-07

56

Microscopic high-speed liquid-metal jets in vacuum  

NASA Astrophysics Data System (ADS)

The operation of microscopic high-speed liquid-metal jets in vacuum has been investigated. We show that such jets may be produced with good stability and collimation at higher speeds than previously demonstrated, provided that the nozzle design is appropriate and that cavitation-induced instabilities are avoided. The experiments with a medium-speed tin jet ( u ˜ 60 m/s, Re=1.8×104, Z=2.9×10-3) showed that it operated without any signs of instabilities, whereas the stability of high-speed tin jets ( d=30 ?m, u=500 m/s, Re=5.6×104, Z=4.7×10-3) has been investigated via dynamic similarity using a water jet. Such a 500-m/s tin jet is required as the anode for high-brightness operation of a novel electron-impact X-ray source.

Otendal, M.; Hemberg, O.; Tuohimaa, T. T.; Hertz, H. M.

2005-11-01

57

Bubbly Jet Impingement in Different Liquids  

Microsoft Academic Search

The impingement of bubbly jets in distilled water and ethanol has been experimentally studied on ground. An experimental apparatus\\u000a for the study of jet impingement on ground and in microgravity has been designed. The opposed-jet configuration with changeable\\u000a orientation is used in order to study which is the better disposition to achieve an efficient mixing process. The impact angle\\u000a between

Francesc Suñol; Ricard González-Cinca

2011-01-01

58

Modeling of turbulence effect on liquid jet atomization  

Microsoft Academic Search

Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. Such turbulent flow phenomena are encountered in most practical applications of common liquid spray devices. Most existing atomization models do not account for the turbulence effects. Only limited attempts have been made to model the subject effects

Huu Phuoc Trinh

2004-01-01

59

Xenon liquid-jet laser plasma source for EUV lithography  

NASA Astrophysics Data System (ADS)

We describe a laser-plasma source based on a cryogenic xenon liquid-jet target suitable for extreme ultraviolet (EUV) projection lithography. Recent improvements in the stability of the xenon jet allows efficient laser-plasma operation several millimeters away from the nozzle orifice. We present the first preliminary laser-to-EUV conversion efficiencies, although under non-optimized conditions, for the source.

Hansson, Bjoern A.; Berglund, Magnus; Hemberg, Oscar; Hertz, Hans M.

2000-07-01

60

Mechanism of air entrainment by a disturbed liquid jet  

NASA Astrophysics Data System (ADS)

It was shown in recent work that the crests of surface disturbances on a falling jet are a powerful agent for air entrainment at the free surface of a liquid pool. The paper explores the opposite case in which the jet is disturbed so as to form an axisymmetric trough, rather than a crest. It is found that no air is entrained in this case. The paper concludes with some considerations on the validity of a recently proposed model for air entrainment.

Ohl, C. D.; Og~Uz, H. N.; Prosperetti, A.

2000-07-01

61

Nozzle-geometry effects in liquid jet impingement heat transfer  

Microsoft Academic Search

Experiments were conducted to determine the effect of nozzle geometry (diameter and aspect ratio) on the local heat transfer coefficients from a small heat source to a normally impinging, axisymmetric, submerged and confined liquid jet of FC-77. A single jet with nozzle diameters in the range of 0.79–6.35 mm and up to seven different nozzle aspect ratios in the range

Suresh V. Garimella; Boris Nenaydykh

1996-01-01

62

Liquid jet impact studies with ordinary and cavijets  

Microsoft Academic Search

Experiments were conducted to study the influence of test duration and stand-off distance on erosion due to liquid jet impact, along with a comparative test of an ordinary jet and a cavijet. Nozzles of 4, 5, 6 and 8.35 mm diameters were used in the velocity range of 13.7 to 30.5 m\\/sec. Aluminium specimens were used in the studies. A

K. S. Janakiram; B. C. Syamala Rao; S. R. Sasikanth

1975-01-01

63

Gas holdup and entrainment characteristics in a modified downflow bubble column with Newtonian and non-Newtonian liquid  

Microsoft Academic Search

Gas entrainment and holdup characteristics have been studied in a downflow bubble column with both Newtonian and non-Newtonian liquid. Aqueous CMC solutions at different concentration were used as a non-Newtonian and water as Newtonian liquid. In the present system, use of plunging liquid jet and ejector were synchronized to obtain significant entrainment and dispersion of gas into liquid. The effects

Ajay Mandal; Gautam Kundu; Dibyendu Mukherjee

2003-01-01

64

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

65

Upward and downward annular liquid jets: Conservation properties, singularities, and numerical errors  

Microsoft Academic Search

A one-dimensional hydraulic model for inviscid incompressible axisymmetric anular liquid jets is derived by assuming that the presure is uniform throughout the jet and that the velocity components are uniform on each cross-section. This model can be derived from that of Boussinesq if the slope of the annular jet is small. Both models indicate that the liquid jet's acceleration and

J. I. Ramos

1996-01-01

66

Shock wave excited liquid micro-jets  

NASA Astrophysics Data System (ADS)

The meniscus of the gas-water interface in a thin hydrophilic capillary of 1mm and less has some similarities to a ``shaped charge'' used to penetrated armored vehicles. In this presentation we show high-speed recordings of the interface dynamics after the reflection from a shock wave: the interface flattens and shapes into a microscopic needle-like jet, which accelerates to velocities of 100m/s and more. Further the dependencies of the pressure amplitude, capillary diameter, and interface curvature on the jet velocity are presented.

Ohl, Claus-Dieter; Martens, Daan; Zijlstra, Aaldert; Versluis, Michel; Lohse, Detlef; de Jong, Nico

2006-11-01

67

Measurement of liquid jet instability induced by surface tension variations  

SciTech Connect

Liquid jet instability was first formally analyzed by Rayleigh over 100 years ago and has since been the subject of a number of investigations. The experimental study reported here took advantage of the fact that the surface tension of water is temperature-dependent and employed a small, fast-responding heater in the orifice of a nozzle to modulate the surface tension along a jet of water issuing into air. This excitation technique produced a regular instability whose growth rates were then measured with a laser measurement technique. Measured growth rates of this thermally excited jet were found to substantially agree with Rayleigh's linear stability theory and with growth rates measured in the same facility from acoustically excited jets. 14 refs.

Faidley, R.W.; Panton, R.L. (Texas Univ., Austin (USA))

1990-07-01

68

Study of liquid jet instability by confocal microscopy.  

PubMed

The instability of a liquid microjet was used to measure the dynamic surface tension of liquids at the surface ages of ?1 ms using confocal microscopy. The reflected light from a laser beam at normal incidence to the jet surface is linear in the displacement of the surface near the confocal position, leading to a radial resolution of 4 nm and a dynamic range of 4 ?m in the surface position, thus permitting the measurement of amplitude of oscillation at the very early stage of jet instability. For larger oscillations outside the linear region of the confocal response, the swell and neck position of the jet can be located separately and the amplitude of oscillation determined with an accuracy of 0.2 ?m. The growth rate of periodically perturbed water and ethanol?water mixture jets with a 100-?m diameter nozzle and mean velocity of 5.7 m s(-1) has been measured. The dynamic surface tension was determined from the growth rate of the instability with a linear, axisymmetric, constant property model. Synchronisation of the confocal imaging system with the perturbation applied to the jet permitted a detailed study of the temporal evolution of the neck into a ligament and eventually into a satellite drop. PMID:22852668

Yang, Lisong; Adamson, Leanne J; Bain, Colin D

2012-07-01

69

Effect of disturbances on air entrainment by impinging liquid jets  

NASA Astrophysics Data System (ADS)

When a steady stream of liquid enters a larger body of still liquid, air may be entrained in the neighborhood of the impingment point. In spite of its commonplace occurrence and engineering importance, this process is not fully understood, although there is little doubt that disturbances on the jet surface (due, e.g., to turbulence) strongly affect air entrainment. This mechanism is probed by using a single well-characterized and reproducible disturbance. The experiment was carried out in a constant-level laboratory tank. A surface disturbance is created on the jet issuing from a nozzles suspended above the water surface by rapidly injecting additional water through four holes in the nozzle. The ensuing disturbance in the receiving water is recorded with a CCD and a high-speed camera. Computer processing of the images permits the extraction of quantitative information that can be used to predict air entrainment from rough jets. In a second experiment a transparent horizontal plate is inserted a few millimeters below the liquid surface so as to produce a circular hydraulic jump. In this case the jet disturbance travels outward toward the jump and entrains air when it hits it. The support of the Office of Naval Research is gratefully acknowledged.

Zhu, Yonggang; Oguz, Hasan N.; Prosperetti, Andrea

1997-11-01

70

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

Microsoft Academic Search

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,

Anu Ranjan Osta

2010-01-01

71

Aqueous molecular clusters isolated as liquid fragments by adiabatic expansion of liquid jets  

Microsoft Academic Search

A new approach to solution chemistry and cluster physics has been developed by combining molecular beam mass-spectrometry with liquid jet expansion method. Many features characteristic of molecular association in aqueous solution were observed in the cluster mass spectra and some of them showed good agreement with reported values of enthalpy changes and entropy changes for molecular association-dissociation equilibria in liquid

N. Nishi

1990-01-01

72

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation  

Microsoft Academic Search

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained

Chin-Shun Lin; Chinshun

1989-01-01

73

Vapor condensation at the free surface of an axisymmetric liquid mixed by a laminar jet  

Microsoft Academic Search

This paper presents numerical solutions of jet-induced mixing in a partially full cryogenic tank. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is

Chin-Shun Lin

1991-01-01

74

The liquid micro-jet from laser induced cavitation bubbles.  

NASA Astrophysics Data System (ADS)

A vaporous cavitation bubble grows spherically in an infinite medium to a maximum radius, collapses in a spherical manner to a minimum volume, and then may rebound one or more times or disintegrate. When the bubble collapses above a solid boundary, the asymmetry of the surrounding flow field will cause the upper bubble surface to cave in, resulting in a fast liquid jet that penetrates its lower surface and continues towards the solid boundary. This fast jet formation is one perceived mechanism for cavitation damage in hydro-machinery. If a hole is intentionally drilled in the solid boundary underneath the collapsing bubble, the fast micro-jet can continue its path and be cultivated for a variety of applications such as micro surgery of soft tissue. In this study, cavitation bubbles are generated by focusing the pulsed IR beam from an Nd-YAG laser above a solid surface. The forming liquid micro-jet is investigated in the cases of blank and drilled solid boundaries.

Abboud, Jack; Oweis, Ghanem

2007-11-01

75

Integrated liquid jet waveguide for fluorescence spectroscopy on chip  

NASA Astrophysics Data System (ADS)

An optofluidic jet waveguide for on chip fluorescence analysis is presented. The waveguide consists of an high speed water jet produced by means of a micro-channel coupled with a multimode optical fiber collecting the fluorescence opportunely excited. The liquid jet acts, at the same time, as the solution to analyse and as an optical waveguide. This configuration allows a strong reduction of the scattering and fluorescence of non analyte substances enabling a very low limit of detection (LOD). The integrated device is fabricated by PMMA micro-machining allowing a self-alignment between the liquid jet waveguide and the optical fiber used to deliver the fluorescence to the detector. The performance of the system has been tested on Cy5 water solutions and LOD of 2.56 nM has been obtained. A proof-of-concept of filter-free measurements has been performed demonstrating that fluorescence measurements can be performed also by using a photodiode with an LOD of 6.11 nM.

Persichetti, Gianluca; Testa, Genni; Bernini, Romeo

2013-03-01

76

Plunge Pools in Submarine Canyons  

NASA Astrophysics Data System (ADS)

Many submarine canyon systems include well-defined intra-canyon depressions. Often, these depressions are found at the base of scarps along the canyon thalweg, with morphologic characteristics similar to subarial plunge pools formed at waterfalls. One plausible mechanism for the origin of these features is scouring during submarine debris flows. Other processes which can plausibly contribute to the formation of re-entrants and depressions in submarine canyons include erosion by spring sapping, slumping, collapse following gas expulsion or subsurface dissolution, and channel damming by mass wasting of canyon walls. We have examined multibeam bathymetry surveys of a number of submarine canyons, and identified more than fifteen apparent plunge pools within submarine canyon systems offshore of Australia, Hawaii, and North America. These features range in scale from 2 km long, 6 km across, and 300 m deep (the largest plunge pool in Perth Canyon, offshore Australia) down to as small as 10 m deep and 150 m across (the smallest plunge pool identified offshore Kohala, Hawaii). Although these features vary considerably in scale, they share common characteristics. Each basin is located at the base of a headwall scarp within the canyon, and is bounded on the down-canyon side by a sill. Measurements of the characteristic dimensions of the plunge pools show that the basin depth (defined relative to the down-canyon sill) increases with the headwall scarp height,. However, the across and down canyon basin widths do not strongly correlate with the scarp height, and seem to be more closely related to the width of the overall canyon channel. The Monterey Bay Aquarium Research Institute investigated three apparent plunge pools using ROV Tiburon during a spring 2001 expedition to the Hawaiian Islands. These basins are located in submarine canyons on the north side of Molokai and the Kohala coast of Hawaii. Our ROV observations support the hypothesis that these intra-canyon depressions are formed through scouring during submarine debris flows. In all cases the down-canyon depression sills are dams composed of debris piles, with angular rubble exposed on the depression side and sand covering the down-canyon side. The Molokai plunge pool is draped with mud and silt, suggesting no recent activity. However, the Kohala plunge pools show clear signs of recent scour and no sediment cover. The headwalls above the plunge pools expose layered volcanoclastic and lava flow units, with more resistant layers frequently forming vertical or overhanging walls. We interpret these canyons as being largely formed through retrogressive (headward) erosion and slope failure. Periodic rockfalls and debris flows following undercutting of the headwalls scours the depressions, builds the pool dams, and both lengthens and deepens the canyons. Modern bathymetric surveys indicate that plunge pools occur in many, but not most submarine canyons. Our ROV observations suggest that stratigraphic variability is a key prerequisite for plunge pool formation. Headwall scarps can persist within active canyons when the existence of more and less resistive layers allows for differential erosion. In turn, plunge pools form when headwall scarps are persistent features.

Caress, D. W.; Greene, H. G.; Paull, C. K.

2002-12-01

77

Liquid-tin-jet laser-plasma extreme ultraviolet generation  

NASA Astrophysics Data System (ADS)

We demonstrate the applicability of liquid-metal jets in vacuum as regenerative targets for laser-plasma generation of extreme ultraviolet (EUV) and soft x-ray radiation. This extends the operation of liquid-jet laser-plasma sources to high-temperature, high-Z, high-density, low-vapor-pressure materials with new spectral signatures. The system is demonstrated using tin (Sn) as the target due to its strong emission around ?~13 nm, which makes the material suitable for EUV lithography. We show a conversion efficiency of 2.5% into (2%BW×2?×sr) and report quantitative measurements of the ionic/atomic as well as particulate debris emission.

Jansson, P. A. C.; Hansson, B. A. M.; Hemberg, O.; Otendal, M.; Holmberg, A.; de Groot, J.; Hertz, H. M.

2004-03-01

78

Breakup characteristics of a liquid jet in subsonic crossflow  

NASA Astrophysics Data System (ADS)

This thesis describes an experimental investigation of the breakup processes involved in the formation of a spray created by a liquid jet injected into a gaseous crossflow. This work is motivated by the utilization of this method to inject fuel in combustors and afterburners of airplane engines. This study aims to develop a better understanding of the spray breakup processes and to provide better experimental inputs to improve the fidelity of numerical models. A review of the literature in this field identified the fundamental physical processes involved in the breakup of the spray and the dependence of spray properties on operating conditions. The time taken for the liquid column to break up into ligaments and droplets, the primary breakup time and the effect of injector geometry on the spray formation processes and spray properties as the key research areas in which research done so far has been inadequate. Determination of the location where the liquid column broke up was made difficult by the presence of a large number of droplets surrounding it. This study utilizes the liquid jet light guiding technique that enables accurate measurements of this location for a wide range of operating conditions. Prior to this study, the primary breakup time was thought to be a function the density ratio of the liquid and the gas, the diameter of the orifice and the air velocity. This study found that the time to breakup of the liquid column depends on the Reynolds number of the liquid jet. This suggests that the breakup of a turbulent liquid jet is influenced by both the aerodynamic breakup processes and the turbulent breakup processes. Observations of the phenomenon of the liquid jet splitting up into two or more jets were made at some operating conditions with the aid of the new visualization technique. Finally, this thesis investigates the effect of injector geometry on spray characteristics. One injector was a round edged orifice with a length to diameter ratio of 1 and a discharge coefficient of 0.95 at the operating conditions of interest. The other injector was a sharp edged orifice with a length to diameter ratio of 10 and a discharge coefficient of 0.74 at the operating conditions of interest. It was shown that the sharp edged orifice was likely to develop cavitation bubbles beyond a flow Reynolds number of 8,000. It was found that a sharp transition in the injector can lead to the liquid column disintegrating sooner. The classical Rayleigh Taylor instabilities that are usually seen with a smooth transition in the injector were not seen in the presence of a sharp transition. The droplets produced with such an injector are larger in size and the spray penetrated deeper into the crossflow.

Gopala, Yogish

79

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

80

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

81

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

NASA Astrophysics Data System (ADS)

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.

1986-07-01

82

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

Microsoft Academic Search

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

James M. Kendall

1986-01-01

83

Effect of air, liquid and injector geometry variables upon the performance of a plain-jet airblast atomizer  

Microsoft Academic Search

Plain air jet air blast atomizer design is undertaken, on the basis of an examination of the breakup characteristics of a discrete liquid jet that is injected into a high velocity cross-flowing airstream, where the variables considered are airstream velocity, liquid jet velocity, injection orifice diameter, liquid viscosity, and liquid surface tension. Tests were conducted in normal atmospheric pressure and

G. A. Hussein; A. K. Jasuja; R. S. Fletcher

1983-01-01

84

Effect of bubbles on the turbulence near the exit of a liquid jet  

Microsoft Academic Search

The objective of this paper is to examine the effect of bubbles on the turbulence levels of a water jet. Simultaneous measurements of the axial and radial velocity components were taken in a bubbly jet with a Laser Doppler Velocimeter (LDV) and then compared to the velocities of a single phase jet at the same liquid flow rate. Mean bubble

S. Kumar; D. N. Nikitopoulos; E. E. Michaelides

1989-01-01

85

Diffusion Bonded EDM Electrode with Micro Holes for Jetting Dielectric Liquid  

Microsoft Academic Search

This paper describes improvement of machining characteristics of electrical discharge machining of deep slots using a tool electrode which has micro holes for jetting dielectric liquid over the working surface. The tool electrode was made by the diffusion bonding of two copper plates, over an interface on which micro grooves for jetting the dielectric fluid were formed using electrolyte jet

T. Shibayama; M. Kunieda

2006-01-01

86

Impulsive plunging wave breaking downstream of a bump in a shallow water flume—Part I: Experimental observations  

NASA Astrophysics Data System (ADS)

The plunging wave-breaking process for impulsive flow over a bump in a shallow water flume is described, which is relevant to ship hydrodynamics albeit for an idealized geometry since it includes the effects of wave-body interactions and the wave breaking direction is opposite to the mean flow. This paper consists of two parts, which deal with experimental measurements and numerical simulations, respectively. In Part I, ensemble-averaged measurements are conducted, including the overall flume flow, 2-D particle image velocimetry (PIV) center-plane velocities, turbulence inside the breaking wave, and bottom pressures under the breaking wave. A series of individual plunging wave-breaking tests were conducted, which all followed a similar time line consisting of startup, steep wave formation, plunging wave breaking, and chaotic wave breaking swept downstream time phases. The plunging wave breaking process consists of four repeated plunging events each with three [jet impact (plunge), oblique splash and vertical jet] sub-events, which were identified first using a complementary computational fluid dynamics (CFD) study. Video images with red dye display the plunging wave breaking events and sub-events. The wave profile at maximum height, first plunge, bump and wave breaking vortex and entrapped air tube trajectories, entrapped air tube diameters, kinetic, potential, and total energy are analyzed. Similarities and differences are discussed with the previous deep water or sloping beach experimental and computational studies. The numerical simulations using the exact experimental initial and boundary conditions are presented in Part II of this paper.

Kang, Donghoon; Ghosh, Surajeet; Reins, George; Koo, Bonguk; Wang, Zhaoyuan; Stern, Frederick

2012-07-01

87

Analysis of interaction phenomena between liquid jets and materials. Revision 1  

SciTech Connect

The interaction phenomena of high-velocity liquid jets impinging on a material surface have been investigated theoretically and experimentally to understand the physics of material removal by jet-machining processes. Experiments were performed to delineate conditions under which liquid jet impacts will cause mass removal, and to determine optimum jet-cutting conditions. Theoretical analyses have also been carried out to study the effects of multiple jet-droplet impacts on a target surface as a material deformation mechanism. The calculated target response and spallation behavior following droplet impacts and their physical implications are also discussed.

Kang, S.W.; Reitter, T.; Carlson, G.

1995-04-01

88

The Bouncing Jet: A Newtonian Liquid Rebounding off a Free Surface  

NASA Astrophysics Data System (ADS)

We find that a liquid jet can bounce off a bath of the same liquid if the bath is moving horizontally with respect to the jet. Previous observations of jets rebounding off a bath (e.g. Kaye effect) have been reported only for non-Newtonian fluids, while we observe bouncing jets in a variety of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable for a range of viscosity, jet flow rate and velocity, and bath velocity. The bouncing jet phenomenon can be observed in many household fluids using only minimal equipment, making it accessible as a classroom demonstration and a science project.

Thrasher, Matthew; Jung, Sunghwan; Pang, Yee Kwong; Chuu, Chih-Piao; Swinney, Harry L.

2007-10-01

89

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

90

Dynamics and breakup of zigzag-like jets of polymeric liquids  

Microsoft Academic Search

Zigzag-like forms of the capillary jet breakdown are detected. The zigzag-like structures observed develop when a water jet\\u000a with polymeric additives flows out from a transverse oscillating capillary. The factor responsible for the unusual behavior\\u000a of the jet is the elasticity of the polymeric liquid. An analysis of the jet shape made it possible to find the elastic stress\\u000a distribution

A. V. Bazilevskii; A. N. Rozhkov

2006-01-01

91

An experimental study of the influence of jet surface roughness on air entrainment at a liquid surface  

Microsoft Academic Search

Bubble production by a small liquid jet at a free surface is studied experimentally. It is well known that the air entrainment is closely related to the jet surface roughness. A special coaxial nozzle in which a liquid jet enters a free surface is used to precisely measure the air entrainment rate as a function of the jet speed. Several

Hasan N. Oguz

1996-01-01

92

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

93

Transverse liquid fuel jet breakup, burning, and ignition. M. S. Thesis  

Microsoft Academic Search

An analytical 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. 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, were used

Hsishang

1990-01-01

94

An investigation of DBD underwater jet plasma properties and its interaction with liquid and solid substrates  

Microsoft Academic Search

Underwater plasma discharges hold great potential for water treatment and chemical processing in liquid systems in general. Such discharges however typically involve small interelectrode spacings or rely on surface diffusion from the gas phase into the liquid. Both situations limit their applicability to high throughput, in-volume water treatment applications. The DBD plasma jet currently under investigation generates a plasma jet

J. E. Foster; M. Gupta; L. Gallagher; B. Weatherford

2010-01-01

95

Experimental study and modeling of nucleate boiling during free planar liquid jet impingement  

Microsoft Academic Search

Determination of boiling heat transfer rate during liquid jet impingement cooling (LJIC) depends on the intensity of bubble generation that is dependent on many flow and surface conditions such as jet velocity, liquid temperature, and surface superheat. Many empirical correlations have been developed previously to determine the total wall heat flux under various LJIC flow velocity, subcooling and surface superheat.

Ahmed M. T Omar

2010-01-01

96

Shock attenuation in two-phase (gas-liquid) jets for inertial fusion applications  

Microsoft Academic Search

Z-Pinch IFE (Inertial Fusion Energy) reactor designs will likely utilize high yield targets (˜ 3 GJ) at low repetition rates (˜ 0.1 Hz). Appropriately arranged thick liquid jets can adequately protect the cavity walls from the target X-rays, ions, and neutrons. However, the shock waves and mechanical loadings produced by rapid heating and evaporation of incompressible liquid jets may be

Celine C. Lascar

2007-01-01

97

Hydrodynamic performance of an annular liquid jet: Production of spherical shells  

Microsoft Academic Search

An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Axisymmetric oscillations arise spontaneously, and grow with such rapidity along the axial dimension that a pinch-off of the liquid and an encapsulation of the core gas occurs within as few as four jet diameters. The shells which result thereby may be described as

J. M. Kendall

1982-01-01

98

Penetration and mixing of bubbling liquid jets from multiple injectors normal to a supersonic air stream  

Microsoft Academic Search

Liquid and bubbling jets are injected from multiple injectors normal to a M = 2.4 airflow and the flow patterns are observed photographically. The penetration and width of the jet plumes are measured utilizing nanoshadowgraphs and front-lighted pictures, respectively. These experiments are conducted at constant supply pressure and constant liquid mass flow rate conditions.

Takakage Arai; Joseph A. Schetz

1992-01-01

99

Numerical Studies of the Effects of Jet-Induced Mixing on Liquid-Vapor Interface Condensation.  

National Technical Information Service (NTIS)

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow r...

C. Lin

1989-01-01

100

Effects of Corona Discharge on the Formation of Electrically-Extracted Liquid Jets  

Microsoft Academic Search

Liquid jets can be extracted from drops when a strong electric field provokes surface instability. The influence of corona discharge from liquid surfaces in air on the dynamic process of jet formation is studied experimentally. A drop of distilled water or KCl aqueous solution is situated at a high voltage metal needle tip and its motion is photographed, with the

Seiji Kuroda; Toshio Horiuchi

1984-01-01

101

Production of jet fuel from coal-derived liquids  

SciTech Connect

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 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. Conceptual designs have been completed and a case for profitable production of JP-8 has been selected for experimental testing and preliminary design in the later phases of the contract. Samples of JP-4, JP-8, and JP-8X aviation turbine fuels have been manufactured from the Great Plains tar oil. Larger samples of JP-8 are nearly completed. Specification of a design basis for profitable production of JP-8 is under way. 5 figs., 4 tabs.

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

1988-01-01

102

Production of jet fuel from coal-derived liquids  

SciTech Connect

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 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. Conceptual designs have been completed and a case for profitable production of JP-8 has been selected for experimental testing and preliminary design. Samples of JP-4, JP-8, and JP-8X aviation turbine fuels have been manufactured from the Great Plains tar oil. Larger samples of JP-8 have also been produced and shipped to the US Air Force for further testing. Lummus-Crest Inc. is now completing a preliminary process design for the profitable production of JP-8 and has made recommendations for a production run to produce larger quantities of JP-8. 2 figs., 3 tabs.

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

1989-01-01

103

Liquid-metal-jet anode x-ray source  

NASA Astrophysics Data System (ADS)

We introduce a novel electron-impact x-ray source based on a high-speed liquid-metal-jet anode. Basic thermal power load calculations indicate that this new anode concept potentially could increase the achievable brightness in compact electron-impact x-ray sources by more than a factor 100 compared to current state-of-the-art rotating-anode or micro-focus sources. A first, successful, low-power proof-of-principle experiment is described and the feasibility of scaling to high-brightness and high-power operation is discussed. Some possible applications that would benefit from such an increase in brightness are also briefly described.

Hemberg, Oscar E.; Otendal, Mikael; Hertz, Hans M.

2004-01-01

104

Liquid-jet laser plasma extreme ultraviolet sources: from droplets to filaments  

NASA Astrophysics Data System (ADS)

The laser plasma is one of the major contenders as a high-power source for future high-volume-manufacturing extreme ultraviolet lithography systems. Such laser-plasma sources require a target system that allows high-repetition-rate operation with low debris and manageable thermal load at the required high laser power. In this paper, we review the development of the liquid-jet target laser plasmas, from droplets to filaments, with special emphasis on its applicability for high-power extreme ultraviolet generation. We focus on two target systems, the liquid-xenon-jet and the liquid-tin-jet.

Hansson, Björn A. M.; Hertz, Hans M.

2004-12-01

105

Effect of bubbles on the turbulence near the exit of a liquid jet  

NASA Astrophysics Data System (ADS)

The objective of this paper is to examine the effect of bubbles on the turbulence levels of a water jet. Simultaneous measurements of the axial and radial velocity components were taken in a bubbly jet with a Laser Doppler Velocimeter (LDV) and then compared to the velocities of a single phase jet at the same liquid flow rate. Mean bubble diameters ranged from 0.6 to 2 mm and the void fractions were up to about 20%. The liquid Reynolds numbers were from 5,000 to 10,000 approximately. The measurements extended to from an axial distance of 4 12 cm. It was observed that bubbles did not affect significantly the average velocity profiles in the jet. However bubbles increased the turbulence intensities in the core of the jet near the jet exit. The increase in turbulence intensities was more pronounced at lower Reynolds numbers and at higher void fractions.

Kumar, S.; Nikitopoulos, D. N.; Michaelides, E. E.

1989-07-01

106

Nanoscale, electrified liquid jets for high resolution printing of charge.  

SciTech Connect

Nearly all research in micro- and nanofabrication focuses on the formation of solid structures of materials that perform some mechanical, electrical, optical, or related function. Fabricating patterns of charges, by contrast, is a much less well explored area that is of separate and growing interesting because the associated electric fields can be exploited to control the behavior of nanoscale electronic and mechanical devices, guide the assembly of nanomaterials, or modulate the properties of biological systems. This paper describes a versatile technique that uses fine, electrified liquid jets formed by electrohydrodynamics at micro- and nanoscale nozzles to print complex patterns of both positive and negative charges, with resolution that can extend into the submicrometer and nanometer regime. The reported results establish the basic aspects of this process and demonstrate the capabilities through printed patterns with diverse geometries and charge configurations in a variety of liquid inks, including suspensions of nanoparticles and nanowires. The use of printed charge to control the properties of silicon nanomembrane transistors provides an application example.

Park, J.-U.; Lee, S.; Unarunotai, S.; Sun, Y.; Dunham, S.; Song, T.; Ferreira, P. M.; Alleyene, A. G.; Paik, U.; Rogers, J. A.; Univ. of Illinois; Hanyang Univ.

2010-02-01

107

Liquid and gas-phase distributions in a jet with phase change  

Microsoft Academic Search

A two-phase flow high-velocity jet with phase change was studied numerically. The jet is assumed to be created by the two-phase critical flow discharge through a pipe of variable length and attached to a vessel containing the saturated liquid at different stagnation pressures. The jet flow is assumed to be axisymmetric and the modeling of the two-phase flow was accomplished

Flavio Dobran

1988-01-01

108

Shock attenuation in two-phase (gas-liquid) jets for inertial fusion applications  

NASA Astrophysics Data System (ADS)

Z-Pinch IFE (Inertial Fusion Energy) reactor designs will likely utilize high yield targets (˜ 3 GJ) at low repetition rates (˜ 0.1 Hz). Appropriately arranged thick liquid jets can adequately protect the cavity walls from the target X-rays, ions, and neutrons. However, the shock waves and mechanical loadings produced by rapid heating and evaporation of incompressible liquid jets may be challenging to accommodate within a small reactor cavity. This investigation examines the possibility of using two-phase compressible (liquid/gas) jets to protect the cavity walls in high yield IFE systems, thereby mitigating the mechanical consequences of rapid energy deposition within the jets. Two-phase, free, vertical jets with different cross sections (planar, circular, and annular) were examined over wide ranges of liquid velocities and void fractions. The void fraction and bubble size distributions within the jets were measured; correlations to predict variations of the slip ratio and the Sauter mean diameter were developed. An exploding wire system was used to generate a shock wave at the center of the annular jets. Attenuation of the shock by the surrounding single- or two-phase medium was measured. The results show that stable coherent jets can be established and steadily maintained over a wide range of inlet void fractions and liquid velocities, and that significant attenuation in shock strength can be attained with relatively modest void fractions (˜ 1%); the compressible two-phase jets effectively convert and dissipate mechanical energy into thermal energy within the gas bubbles. The experimental characteristics of single- and two-phase jets were compared against predictions of a state-of-art CFD code (FLUENTRTM ). The data obtained in this investigation will allow reactor system designers to predict the behavior of single- and two-phase jets and quantify their effectiveness in mitigating the consequences of shock waves on the cavity walls in high yield IFE systems.

Lascar, Celine C.

109

Dynamic behavior of reacting gas jets submerged in liquids  

Microsoft Academic Search

A photographic study of a hydrogen chloride gas jet reacting in an aqueous solution of ammonia was conducted. The high-speed motion pictures taken revealed that the behavior of the reacting gas jet was highly dynamic and complex. The gaseous jet penetration (plume) was not stationary, but underwent a change in shape and size with time, which appeared to be periodic

D. H. Cho; D. R. Armstrong; L. Bova

1987-01-01

110

Coaxial atomization of a round liquid jet in a high speed gas stream: A phenomenological study  

Microsoft Academic Search

Coaxial injectors have proven to be advantageous for the injection, atomization and mixing of propellants in cryogenic H2\\/O2 rocket engines. Thereby, a round liquid oxygen jet is atomized by a fast, coaxial gaseous hydrogen jet. This article summarizes phenomenological studies of coaxial spray generation under a broad variation of influencing parameters including injector design, inflow, and fluid conditions. The experimental

W. O. H. Mayer

1994-01-01

111

A molecular beam study of the evaporation of water from a liquid jet  

Microsoft Academic Search

A method to maintain a clean surface of a liquid in a high vacuum is described. Using a very thin and fast liquid jet it is not only possible to prevent freezing of the liquid but also to reduce the number of collisions between evaporating molecules to negligibly small values. Thus many of the standard, vacuum dependent, particle probing techniques

M. Faubel; S. Schlemmer; J. P. Toennies

1988-01-01

112

Novel Laser-Based Technique for Measurements of Primary Atomization Characteristics of Liquid Jets.  

National Technical Information Service (NTIS)

The purpose of the research documented herein is to provide guidelines for the application of a novel optical technique, developed uniquely at Imperial College, London, UK, for measurements of primary atomization characteristics of liquid jets in differen...

Y. Hardalupas

2012-01-01

113

High heat-flux accelerator targets: Cooling with liquid metal jet impingement  

Microsoft Academic Search

In order to evaluate the performance of jet impingement for high heat-flux cooling, experimental cooling loops based on water and liquid metal jet impingement were designed and constructed. The current liquid metal system, based on an eutectic alloy of gallium and indium (GaIn) with a melting point of 15.7°C, employs an annular inductive electromagnetic pump. The experiments showed that it

I. Silverman; A. L. Yarin; S. N. Reznik; A. Arenshtam; D. Kijet; A. Nagler

2006-01-01

114

Impulsive plunging wave breaking downstream of a bump in a shallow water flume—Part II: Numerical simulations  

NASA Astrophysics Data System (ADS)

Part II of this two-part paper presents the simulation results of the plunging wave-breaking generated by impulsive flow over a submerged bump fixed in a shallow water flume using the exact experimental initial and boundary conditions provided in Part I of this study. The overall plunging wave breaking process is described with major wave breaking events identified: jet plunge, oblique splash and vertical jet. These major events repeat up to four times before entering the chaotic breaking phase. The plunging wave breaking process of the simulations shows a similar time line as the experiments consisting of startup, steep wave formation, plunging wave, and chaotic wave breaking swept downstream time phases. Wave breaking profile, air entrainment, velocity, vorticity, flume bottom pressure, and energy are analyzed and compared with the experimental results. The simulations qualitatively predict all four time phases, all four plunging events and their sub-events. The wave profile and location at the maximum height is very close to the experiment results. The flume flow and velocity demonstrate the same flow trend as the experiments but with reduced velocity magnitudes. The simulations show similar bottom pressure to the experiments but with large oscillations, and the post-breaking water elevations are larger as compared to the experimental results.

Koo, Bonguk; Wang, Zhaoyuan; Yang, Jianming; Stern, Frederick

2012-07-01

115

Supersonic liquid fuel jets injected into quiescent air  

Microsoft Academic Search

Supersonic fuel jets may have applications in diesel engine and scramjet technology. Their properties require a fundamental examination as their mixing characteristics are likely to be affected by the leading edge shock wave. Such jets have been created experimentally in the laboratory but require further CFD studies to examine details that are obscure in the experiments. This paper reports on

S. Zakrzewski; B. E. Milton; K. Pianthong; M. Behnia

2004-01-01

116

Asymptotic analysis of compound liquid jets at low Reynolds numbers  

Microsoft Academic Search

Asymptotic methods based on the slenderness ratio are used to obtain the leading-order equations which govern the fluid dynamics of both hollow and solid, compound jets such as those employed in the manufacture of textile fibers, composite fibers and optical fibers. These fibers consist of an inner material which may be a round jet or an annular one and which,

J. I. Ramos

1999-01-01

117

GAS JET IMPINGING ON LIQUID SURFACE: CAVITY SHAPE MODELLING AND VIDEO-BASED ESTIMATION  

Microsoft Academic Search

A water model is studied to simulate physical phenomena in the LD steel converter. The depression in the liquid, due to the impinging gas jet, is measured by means of a video camera. Image processing tools together with a nonlinear mathematical model based on the physics of the liquid-gas system, are used to describe the cavity profile. The properties of

Magnus Evestedt; Alexander Medvedev

2005-01-01

118

Capillary nozzles for liquid-jet laser-plasma x-ray sources  

NASA Astrophysics Data System (ADS)

We describe a method to fabricate tapered glass nozzles suitable for liquid-jet-target generation in laser-plasma soft x-ray and extreme ultraviolet sources. In the method, a tapered nozzle is formed as an integral part of a flexible capillary glass tubing. The method makes use of inert materials, extending the possible choice of target liquids compared to current nozzles. It also provides flexibility as regards nozzle diameter and pressure, thereby allowing optimization of the target size and extending the range of applicability for the liquid-jet-target laser plasmas.

de Groot, J.; Johansson, G. A.; Hertz, H. M.

2003-08-01

119

On the mechanism of air entrainment by liquid jets at a free surface  

NASA Astrophysics Data System (ADS)

The process by which a liquid jet falling into a liquid pool entrains air is studied experimentally and theoretically. It is shown that, provided the nozzle from which the jet issues is properly contoured, an undisturbed jet does not entrap air even at relatively high Reynolds numbers. When surface disturbances are generated on the jet by a rapid increase of the liquid flow rate, on the other hand, large air cavities are formed. Their collapse under the action of gravity causes the entrapment of bubbles in the liquid. This sequence of events is recorded with a CCD and a high-speed camera. A boundary-integral method is used to simulate the process numerically with results in good agreement with the observations. An unexpected finding is that the role of the jet is not simply that of conveying the disturbance to the pool surface. Rather, both the observed energy budget and the simulations imply the presence of a mechanism by which part of the jet energy is used in creating the cavity. A hypothesis on the nature of this mechanism is presented.

Zhu, Yonggang; O[Gbreve]Uz, Hasan N.; Prosperetti, Andrea

2000-02-01

120

Mixing characteristics of pulsed air-assist liquid jet into an internal subsonic cross-flow  

NASA Astrophysics Data System (ADS)

Penetration depth, spray dispersion angle, droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing engine. These processes will enhance air/fuel mixing inside the combustor. Experimental results from the pulsed air-assist liquid jet injected into a cross-flow are investigated. And experiments were conducted to a range of cross-flow velocities from 42˜136 m/s. Air is injected with 0˜300kPa, with air-assist pulsation frequency of 0˜20Hz. Pulsation frequency was modulated by solenoid valve. Phase Doppler Particle Analyzer(PDPA) was utilized to quantitatively measuring droplet characteristics. High-speed CCD camera was used to obtain injected spray structure. Pulsed air-assist liquid jet will offer rapid mixing and good liquid jet penetration. Air-assist makes a very fine droplet which generated mist-like spray. Pulsed air-assist liquid jet will introduce additional supplementary turbulent mixing and control of penetration depth into a cross-flow field. The results show that pulsation frequency has an effect on penetration, transverse velocities and droplet sizes. The experimental data generated in these studies are used for a development of active control strategies to optimize the liquid jet penetration in subsonic cross-flow conditions and predict combustion low frequency instability.

Lee, Inchul; Kang, Youngsu; Koo, Jaye

2010-04-01

121

Liquid-metal-jet anode electron-impact x-ray source  

NASA Astrophysics Data System (ADS)

We demonstrate an anode concept, based on a liquid-metal jet, for improved brightness in compact electron-impact x-ray sources. The source is demonstrated in a proof-of-principle experiment where a 50 keV, ~100 W electron beam is focused on a 75 ?m liquid-solder jet. The generated x-ray flux and brightness is quantitatively measured in the 7-50 keV spectral region and found to agree with theory. Compared to rotating-anode sources, whose brightness is limited by intrinsic thermal properties, the liquid-jet anode could potentially be scaled to achieve a brightness >100× higher than current state-of-the-art sources. Applications such as mammography, angiography, and diffraction would benefit from such a compact high-brightness source.

Hemberg, O.; Otendal, M.; Hertz, H. M.

2003-08-01

122

Improved liquid jet laser-plasma source for X-ray microscopy  

NASA Astrophysics Data System (ADS)

We increase the x-ray flux from a liquid-jet laser-plasma x-ray source by optimizing the target geometry. A new nozzle fabrication method allows us to produce stable microscopic liquid jets with a wide range of diameters. The improved x-ray flux is demonstrated by optimizing the diameter of an ethanol liquid-jet for our 3 ns, square=532 nm Nd: YAG laser and measuring the flux at the square=3.37 nm C VI emission line. Preliminary data suggest that the x-ray flux can be increased by more than a factor of 4 compared to previous experiments. The goal is to significantly reduce the exposure time of our laser-plasma-based compact x-ray microscope by improving the source.

de Groot, J.; Johansson, G. A.; Hemberg, O.; Hertz, H. M.

2003-03-01

123

High-intensity electron beam for liquid-metal-jet anode hard x-ray generation  

NASA Astrophysics Data System (ADS)

We report on our progress towards the experimental realization of a liquid-metal-jet-anode x-ray source with high brightness. We have previously shown that this electron-impact source has potential for very high x-ray brightness by combining small-spot high-flux operation of the electron beam with high-speed operation of the regenerative liquid-metal-jet anode. In the present paper we review the system and describe theoretical calculations for improving the 50 kV, 600 W electron-beam focussing to ~30 ?m spot size. With such a system the power density on the liquid-metal-jet would be ~400 kW/mm2, i.e., more than an order of magnitude higher than the power density on a state-of-the-art rotating anode.

Tuohimaa, Tomi; Otendal, Mikael; Hertz, Hans M.

2005-08-01

124

Confined jet impingement of liquid nitrogen onto different heat transfer surfaces  

NASA Astrophysics Data System (ADS)

Jet impingement of liquid nitrogen owns many applications in the cryogenic cooling aspects, such as, cooling of high-power chips in the electronic devices and cryoprobes in the cryosurgery. In the present study, we systematically investigated the confined jet impingement of liquid nitrogen from a tube of about 2.0 mm in diameter onto the heat transfer surfaces of about 5.0 mm in basement diameter with different heat transfer surface geometries and conditions, i.e., flat surface, hemispherical surface and flat surface with a needle. The effects of many influential factors, such as, the geometry of the heat transfer surface, jet velocity, distance between the nozzle exit and heat transfer surface, heat transfer surface condition, and some other, on the heat transfer were investigated. The heat transfer correlations were also proposed by using the experimental data, and it was found that the heat transfer mechanism of liquid impingement in the confined space was dominated by the convective evaporation rather than the nucleate boiling in the present case. The critical heat flux (CHF) of the confined jet impingement was measured and the visualization of the corresponding flow patterns of the confined jet impingement of liquid nitrogen was also conducted simultaneously to understand the heat transfer phenomena.

Zhang, P.; Xu, G. H.; Fu, X.; Li, C. R.

2011-06-01

125

Numerical investigation on the primary breakup of an inelastic non-Newtonian liquid jet with inflow turbulence  

NASA Astrophysics Data System (ADS)

Direct Numerical Simulations of the primary breakup of an inelastic non-Newtonian liquid jet with inflow turbulence are presented in this paper. The jet's structure, surface behavior, non-Newtonian characteristics as well as its specific breakup mechanism are investigated and discussed. The shear thinning viscosity of the liquid phase plays an important role during jet injection resulting in circumferential rotation of interfacial waves. Streamwise contra-rotating vortex pairs as well as triple vortex structures are observed in the liquid phase. The local Ohnesorge number, which has a branch-structure distribution in the liquid phase before disintegration, is found to be 30% smaller in regions near the nozzle exit and in the shear layer than in the jet tip, suggesting a clear non-Newtonian influence. A cavity breakup mechanism for this type of non-Newtonian jet is identified and explained, giving a new perspective for jet disintegration analysis.

Zhu, Chengxiang; Ertl, Moritz; Weigand, Bernhard

2013-08-01

126

X-ray grating interferometry with a liquid-metal-jet source  

NASA Astrophysics Data System (ADS)

A liquid-metal-jet X-ray tube is used in an X-ray phase-contrast microscope based on a Talbot type grating interferometer. With a focal spot size in the range of a few microns and a photon flux of ~1012 photons/s×sr, the brightness of such a source is approximately one order of magnitude higher than for a conventional microfocus source. For comparison, a standard microfocus source was used with the same grating interferometer, showing significantly increased visibility for the liquid-metal-jet arrangement. Together with the increased flux, this results in improved signal-to-noise ratio.

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

2013-08-01

127

Hydrodynamic performance of an annular liquid jet: Production of spherical shells  

NASA Astrophysics Data System (ADS)

An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Axisymmetric oscillations arise spontaneously, and grow with such rapidity along the axial dimension that a pinch-off of the liquid and an encapsulation of the core gas occurs within as few as four jet diameters. The shells which result thereby may be described as thick-wall bubbles, for which van der Waals forces are unimportant. A description is given of the fluid dynamic processes by which the shells are formed, and of means for preserving and promoting the geometrical of the product. The forming of metallic shells is mentioned.

Kendall, J. M.

1982-03-01

128

The self limiting effect of hydrogen cluster in gas jet under liquid nitrogen temperature  

SciTech Connect

The generation of hydrogen clusters in gas jet is tested using the Rayleigh scattering method under liquid nitrogen temperature of 79 K. The self limiting effect of hydrogen cluster is studied and it is found that the cluster formation is greatly affected by the number of expanded molecules. The well designed liquid nitrogen cold trap ensured that the hydrogen cluster would keep maximum size for maximum 15 ms during one gas jet. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 5 to 48 bar with the power value of 4.1.

Han Jifeng; Yang Chaowen; Miao Jingwei; Fu Pengtao; Luo Xiaobing; Shi Miangong [Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China)

2010-09-15

129

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

130

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

131

Interaction of a liquid flow around a micropillar with a gas jet  

NASA Astrophysics Data System (ADS)

An experimental study was conducted to investigate two-phase flow characteristics resulting from gas jet injection into a 225 ?m high by 1500 ?m wide microchannel. The jet was injected from a 25 ?m wide slit on the downstream side of a 150 ?m diameter pillar. The liquid Reynolds number (Re = ?UD/?) based on pillar diameter ranged from 100 to 700, and the average gas momentum coefficient (?jetUjetAjet/?mainUmainAref), defined as the ratio of gas momentum to liquid momentum, ranged from 1.6 × 10-5 to 3.368 × 10-1. Flow visualization, micro particle image velocimetry (?PIV), and micro particle tracing velocimetry (?PTV) were used to elucidate the two-phase flow patterns, liquid velocity field, and bubble dynamics. Two modes of gas jets were observed in which bubbles either formed and detached at the pillar or formed an attached ligament that sheared bubbles from its trailing edge. The modes were determined to be primarily Reynolds number dependent. Both modes were observed to positively affect turbulent kinetic energy in the microchannel. The momentum coefficient of the gas jet had the most significant effect at low Reynolds numbers, when bubble formation took place at the pillar.

Elcock, D.; Jung, J.; Kuo, C.-J.; Amitay, M.; Peles, Y.

2011-12-01

132

Gravitational radiation from plunging orbits: Perturbative study  

SciTech Connect

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 [California Institute of Technology, MC 130-33, Pasadena, California 91125 (United States)

2008-12-15

133

An experimental study of the influence of jet surface roughness on air entrainment at a liquid surface.  

NASA Astrophysics Data System (ADS)

Bubble production by a small liquid jet at a free surface is studied experimentally. It is well known that the air entrainment is closely related to the jet surface roughness. A special coaxial nozzle in which a liquid jet enters a free surface is used to precisely measure the air entrainment rate as a function of the jet speed. Several types of nozzles of diameters ranging from 1.6 mm to 2.4 mm are employed. The profiles of the jets are measured from digitized photographs. The jet surface roughness is deduced as a function of the distance from the nozzle exit. This is necessary because the local roughness at the impact point dictates the entrainment process. A relationship between the jet surface roughness and the air entrainment rate is established. Numerical simulations of an idealized bubble formation event are carried out and seem to support the experimental findings. Work supported by NSF Grant CTS9318724.

Oguz, Hasan N.

1996-11-01

134

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

135

A 24 keV liquid-metal-jet x-ray source for biomedical applications  

NASA Astrophysics Data System (ADS)

We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30-70 W electron beam is magnetically focused onto the jet, producing a circular 7-13 ?m full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In K? line is 3 × 109 photons/(s × mm2 × mrad2 × 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

Larsson, D. H.; Takman, P. A. C.; Lundström, U.; Burvall, A.; Hertz, H. M.

2011-12-01

136

A 24 keV liquid-metal-jet x-ray source for biomedical applications  

SciTech Connect

We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30-70 W electron beam is magnetically focused onto the jet, producing a circular 7-13 {mu}m full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In K{sub {alpha}} line is 3 x 10{sup 9} photons/(s x mm{sup 2}x mrad{sup 2}x 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

Larsson, D. H.; Takman, P. A. C.; Lundstroem, U.; Burvall, A.; Hertz, H. M. [Biomedical and X-Ray Physics, Department of Applied Physics, Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden)

2011-12-15

137

Direct numerical simulation of ignition in turbulent n-heptane liquid-fuel spray jets  

Microsoft Academic Search

Direct numerical simulation was used for fundamental studies of the ignition of turbulent n-heptane liquid-fuel spray jets. A chemistry mechanism with 33 species and 64 reactions was adopted to describe the chemical reactions. The Eulerian method is employed to solve the carrier-gas flow field and the Lagrangian method is used to track the liquid-fuel droplets. Two-way coupling interaction is considered

Y. Wang; C. J. Rutland

2007-01-01

138

Role of surfactant in the breakup of liquid jets in food processing operations  

Microsoft Academic Search

The spontaneous break up into drops of a liquid jet is a fluid-dynamical process that impacts many important food and agricultural applications from spray drying of liquid foods and atomization of fertilizers and pesticides, to emerging applications such as protein micro-arraying and micro- and nano-encapsulation of flavors and nutrients. While the desired drop sizes differ widely among these applications, the

Sirichai Songsermpong

2006-01-01

139

Structure–property relationships in liquid jet erosion of tungsten carbide hardmetals  

Microsoft Academic Search

The National Physical Laboratory has recently commissioned a liquid jet erosion rig capable of infinitely variable impingement velocities and slurry erodent volume fractions. Initial work using the new tribometer is being focussed on hardmetals based on tungsten carbide, either with a cobalt binder or cobalt\\/nickel binder. Investigations have been conducted into correlating wear behaviour with conventional parameters used for characterising

A. J. Gant; M. G. Gee

2009-01-01

140

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

141

GAS INDUCTION AND HOLD-UP CHARACTERISTICS OF LIQUID JET LOOP REACTORS  

Microsoft Academic Search

Gas induction and hold-up characteristics of liquid jet loop reactors (LJLR) have been studied. From the results of these investigations with various diffuser geometries the effect of various parts of the diffuser on the rate of induction, QG, and the gas hold-up, EG, have been discerned. Two different diffuser designs yield highest EG and QG, respectively. The use of draft

S. R. BHUTADA; V. G. PANGARKAR

1987-01-01

142

An atmospheric-pressure microplasma jet source for the optical emission spectroscopic analysis of liquid sample  

Microsoft Academic Search

A miniaturized atmospheric-pressure thermal plasma jet source has been developed as a sensitive detector of a portable liquid analysis system that can fulfil various requirements of `on-site' analysis. The plasma source design required for achieving higher power transfer efficiency to the plasma has been studied mainly so that it can be operated with a commercially available compact VHF transmitter. The

Takanori Ichiki; Toru Koidesawa; Yasuhiro Horiike

2003-01-01

143

Conjugate problem of aerodynamic extrusion of jets of heated viscous liquid  

Microsoft Academic Search

Aerodynamic extrusion of jets of viscous liquids is of practical value for the production of synthetic filaments consisting of polymer melts with the help of high-velocity gas flows. The problem of fiber formation is a conjugate problem, in which the mutual effect of the fiber formed and the surrounding medium must be taken into account. This problem was first formulated

V. I. Eliseev; L. A. Fleer

1988-01-01

144

Atomization patterns produced by the oblique collision of two Newtonian liquid jets  

NASA Astrophysics Data System (ADS)

This paper reports a detailed experimental investigation of the formation, destabilization, and atomization of the liquid sheets created by the oblique impact of two laminar jets of a Newtonian liquid. Glycerol-water mixtures with viscosities between 4 and 30 mPa s were used to investigate the effects of viscosity and jet velocity. The jets were ejected from parallel cylindrical nozzles with an internal diameter of 0.85 mm. Collision of the jets resulted in various regimes of behavior which depend on the jet velocities and the liquid properties. We focus on the regime where the impinging jets form a liquid sheet which then breaks up into a regular succession of ligaments and droplets, a so-called ``fishbone'' pattern. We use short-duration, single-flash illumination combined with high-resolution digital photography to study the evolution of the sheet, its shape, and the form, size, and spacing of resulting ligaments and drops. Unexpectedly, we found fishbone regimes corresponding to lower Reynolds and Weber numbers than had been previously reported; furthermore our apparently symmetric fishbone structures were definitely associated with asymmetric, rather than symmetric, impacting jet conditions. The fishbone structure was found to be significantly affected by any asymmetry in either the free lengths of the two jets or their alignment. The fishbone angle, defined as the angle between the lines through the first pairs of droplets on each side of the fishbone structure, is introduced to describe the effects of differences in jet length, alignment, or fluid properties on the degree of development of the fishbone pattern. We discuss how changes in the various parameters influence the form of the fishbone pattern and the origin and mechanism of the periodic atomization of the sheet. In particular we find that the dependence of the drop spacing on viscosities is consistent with the Rayleigh-Plateau instability on the rim provided the variation of the rim width is properly included, as this dominates the Ohnesorge number dependence of the breakup.

Jung, Sungjune; Hoath, Stephen D.; Martin, Graham D.; Hutchings, Ian M.

2010-04-01

145

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

SciTech Connect

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 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. [Associacao EURATOM/IST, Centro de FuSao Nuclear, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I. [Association EURATOM/University of Latvia, Institute of Physics, 32 Miera Str., Salaspils, LV-2169 (Latvia)

2006-12-04

146

An atmospheric-pressure microplasma jet source for the optical emission spectroscopic analysis of liquid sample  

NASA Astrophysics Data System (ADS)

A miniaturized atmospheric-pressure thermal plasma jet source has been developed as a sensitive detector of a portable liquid analysis system that can fulfil various requirements of `on-site' analysis. The plasma source design required for achieving higher power transfer efficiency to the plasma has been studied mainly so that it can be operated with a commercially available compact VHF transmitter. The developed plasma device is a planar-type inductively coupled plasma (ICP) source that consists of a ceramic chip with engraved discharge tube and a planar metallic antenna with serpentine structures. Effects of chip materials and antenna designs on plasma characteristics are discussed based on the result of optical diagnostics of fine argon plasma jets produced with various prototype sources. Since the load impedance of the plasma jet is so small, it is necessary to contrive ways to lower the antenna impedance to attain higher power transfer efficiency. An atmospheric-pressure thermal plasma jet with a density of approximately 1×1015 cm-3 was successfully produced using a compact VHF transmitter at the 144 MHz VHF power of 50 W. The electronic excitation temperature of Ar was found to be 4000-4500 K. Moreover, the method of injection of the liquid sample into microplasma jets has also been investigated and preliminary results of the application to the analysis of tiny amounts of aqueous solution have been demonstrated.

Ichiki, Takanori; Koidesawa, Toru; Horiike, Yasuhiro

2003-11-01

147

Predicting Impact Velocities of Developed Jets  

Microsoft Academic Search

Dam overtopping often results in the erosion of foundation and abutment materials. To quantify erosion potential, the jet impact velocity at the plunge pool interface must be estimated. Regións of the overtopping jet trajectory through free-fall are termed undeveloped (compact) and developed (individual particles). A physical model was constructed to simulate the developed region of a free-falling jet and to

Todd M. Lewis; Steven R. Abt; F. Rodney J. Wittler; George W. Annandale

1999-01-01

148

Study on bubble sizes in a down-flow liquid jet gas pump  

NASA Astrophysics Data System (ADS)

In this paper the liquid jet gas pump as an important gas-liquid contactor is investigated on bubble sizes. Its internal mixed effect is influenced by gas holdup, bubble size distribution and interfacial area. To improve the mixed effect, experiment investigations have been carried out in a modified down-flow liquid jet gas pump with special emphasis on gas distribution. The mixing tube and diffuser are made of transparent Perspex for visual observation. Bubble diameters in the diffuser have been measured by photographic and capillary method at different operating conditions. Under the same Reynolds number of orifice, about 80% of the bubble diameters range from 0.6 mm to 1.3 mm, which has no obvious effect on the gas-liquid flow rate ratio. The average bubble diameter increases by the decrease of Orifice Reynolds number at the same gas-liquid flow rate ratio (lower gas-liquid rate ratio), the maximal bubble size can reach 3 mm. With the decrease of gas-liquid flow rate ratio, gas gathers together in the wall and the stream appears non uniform, the sampling test shows that the bubble diameters have a small diminution. It is found experimentally that the bubble diameters are strongly dependent on Orifice Reynolds number and the bubble distribution is affected by gas-liquid flow rate ratio

Wu, Y. L.; Xiang, Q. J.; Li, H.; Chen, S. X.

2012-11-01

149

Time-resolved dynamics of laser-induced micro-jets from thin liquid films  

Microsoft Academic Search

Laser-induced forward transfer (LIFT) is a high-resolution direct-write technique, which can print a wide range of liquid\\u000a materials without a nozzle. In this process, a pulsed laser initiates the expulsion of a high-velocity micro-jet of fluid\\u000a from a thin donor film. LIFT involves a novel regime for impulsively driven free-surface jetting in that viscous forces developed\\u000a in the thin film

Matthew S. Brown; Nicholas T. Kattamis; Craig B. Arnold

2011-01-01

150

X-ray and EUV laser-plasma sources based on cryogenic liquid-jet target  

NASA Astrophysics Data System (ADS)

We describe new high-brightness laser-plasma sources for x- ray and extreme UV (EUV) radiation. By utilizing a microscopic liquid-jet or liquid-droplet target the harmful emission of debris is significantly reduced or completely eliminated. The spectrum can be spectrally tailored by choosing a suitable liquid. In this paper we summarize our work on this type of source and include some recent developments on cryogenic liquified gases such as nitrogen and xenon. We believe that this new source is a suitable choice for EUV lithography as well as for proximity x-ray lithography.

Rymell, Lars; Berglund, Magnus; Hansson, Bjorn A.; Hertz, Hans M.

1999-06-01

151

Giant plunging ranula: a case report  

PubMed Central

A ranula is a bluish, transparent, and thin-walled swelling in the floor of the mouth. They originate from the extravasation and subsequent accumulation of saliva from the sublingual gland. Ranulas are usually limited to the sublingual space but they sometimes extend to the submandibular space and parapharyngeal space, which is defined as a plunging ranula. A 21-year-old woman presented with a complaint of a large swelling in the left submandibular region. On contrast-enhanced CT images, it dissected across the midline, and extended to the parapharyngeal space posteriorly and to the submandibular space inferiorly. Several septa and a fluid-fluid level within the lesion were also demonstrated. We diagnosed this lesion as a ranula rather than cystic hygroma due to the location of its center and its sublingual tail sign. As plunging ranula and cystic hygroma are managed with different surgical approaches, it is important to differentiate them radiologically.

Kim, Seong-Ha; An, Chang-Hyeon; Park, Jin-Woo; Yi, Won-Jin

2013-01-01

152

Ultrafast X-ray study of dense-liquid-jet flow dynamics using structure-tracking velocimetry  

Microsoft Academic Search

High-speed liquid jets and sprays are complex multiphase flow phenomena with many important industrial applications. Great efforts have been devoted to understand their dynamics since the pioneering work of Rayleigh on low-speed jets. Attempts to use conventional laser optical techniques to provide information about the internal structure of high-speed jets have been unsuccessful owing to the multiple scattering by droplets

Yujie Wang; Xin Liu; Kyoung-Su Im; Wah-Keat Lee; Jin Wang; David L. S. Hung; James R. Winkelman; Kamel Fezzaa; Visteon Corp

2008-01-01

153

Theoretical analysis of specimen cooling rate during impact freezing and liquid-jet freezing of freeze-etch specimens.  

PubMed Central

We have carried out a theoretical analysis of specimen cooling rate under ideal conditions during impact freezing and liquid-jet freezing. The analysis shows that use of liquid helium instead of liquid nitrogen as cooling medium during impact freezing results in an increase in a specimen cooling rate of no more than 30-40%. We have further shown that when both impact freezing and liquid-jet freezing are conducted at liquid nitrogen temperature, the two methods give approximately the same specimen cooling rate under ideal conditions except for a thin outer layer of the specimen. In this region impact freezing yields the highest cooling rate.

Kopstad, G; Elgsaeter, A

1982-01-01

154

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

NASA Astrophysics Data System (ADS)

We demonstrate stable operation of a nonmetallic anode in an electron-impact x-ray source. A high-brightness electron beam is focused on a ~70 m/s speed, ~10 ?m diameter methanol jet producing stable x-ray emission with peak spectral brightness at ~5.4×105 photons/(s×?m2×sr×0.1%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.; Fernández-Varea, J. M.; Hertz, H. M.; Vogt, U.

2008-06-01

155

Direct numerical simulation of ignition in turbulent n-heptane liquid-fuel spray jets  

SciTech Connect

Direct numerical simulation was used for fundamental studies of the ignition of turbulent n-heptane liquid-fuel spray jets. A chemistry mechanism with 33 species and 64 reactions was adopted to describe the chemical reactions. The Eulerian method is employed to solve the carrier-gas flow field and the Lagrangian method is used to track the liquid-fuel droplets. Two-way coupling interaction is considered through the exchange of mass, momentum, and energy between the carrier-gas fluid and the liquid-fuel spray. The initial carrier-gas temperature was 1500 K. Six cases were simulated with different droplet radii (from 10 to 30 {mu}m) and two initial velocities (100 and 150 m/s). From the simulations, it was found that evaporative cooling and turbulence mixing play important roles in the ignition of liquid-fuel spray jets. Ignition first occurs at the edges of the jets where the fuel mixture is lean, and the scalar dissipation rate and the vorticity magnitude are very low. For smaller droplets, ignition occurs later than for larger droplets due to increased evaporative cooling. Higher initial droplet velocity enhances turbulence mixing and evaporative cooling. For smaller droplets, higher initial droplet velocity causes the ignition to occur earlier, whereas for larger droplets, higher initial droplet velocity delays the ignition time. (author)

Wang, Y.; Rutland, C.J. [Department of Mechanical Engineering, University of Wisconsin-Madison, WI 53706 (United States)

2007-06-15

156

Plunge Pools in Hawaiian Submarine Canyons  

NASA Astrophysics Data System (ADS)

Many submarine canyon systems include well-defined intra-canyon depressions. Often, these depressions are found at the base of scarps along the canyon thalweg, with morphologic characteristics similar to subarial plunge pools formed at waterfalls. One plausible mechanism for the origin of these features is scouring during submarine debris flows. Other processes which can plausibly contribute to the formation of re-entrants and depressions in submarine canyons include erosion by spring sapping, slumping, collapse following gas expulsion or subsurface dissolution, and channel damming by mass wasting of canyon walls. The Monterey Bay Aquarium Research Institution conducted ROV dives around the Hawaiian Islands during a spring 2001 expedition of the R/V Western Flyer and ROV Tiburon. Three ROV dives investigated submarine canyons on the north (windward) sides of Molokai and Hawaii that exhibit well-developed intra-canyon depressions. These depressions ranged from 10 m deep and 150 m across to 90 m deep and 750 m across. The headwall scarps ranged from 20 m to 350 m. ROV video observations combined with rock and sediment sampling allowed us to characterize the depressions' detailed morphology, relate the morphology to the underlying geology, and view the genesis of these features in the context of the origin and evolution of the canyon systems as a whole. Our observations support the hypothesis that these intra-canyon depressions, or plunge pools, are formed through scouring during submarine debris flows. In all cases the down-canyon depression sills are dams composed of debris piles, with angular rubble exposed on the depression side and sand covering the down-canyon side. The Molokai plunge pool is draped with mud and silt, suggesting no recent activity. However, the Kohala plunge pools show clear signs of recent scour and no sediment cover. The headwalls above the plunge pools expose layered volcanoclastic and lava flow units, with more resistant layers frequently forming vertical or overhanging walls. We interpret these canyons as being largely formed through retrogressive (headward) erosion and slope failure. Periodic rockfalls and debris flows following undercutting of the headwalls scours the depressions, builds the pool dams, and both lengthens and deepens the canyons. >http://www.mbari.org/education/cruises/Hawaii/

Caress, D. W.; Greene, H. G.; Greene, H. G.; Paull, C. K.; Ussler, W.; Clague, D.; Moore, J. G.; Maher, N. H.

2001-12-01

157

Vapor condensation at the free surface of an axisymmetric liquid mixed by a laminar jet  

NASA Astrophysics Data System (ADS)

This paper presents numerical solutions of jet-induced mixing in a partially full cryogenic tank. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to slove the nondimensional form of steady-state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of previously stated parameters on the condensation Nusselt and Stanton numbers that characterize the steady-state interface condensation process are investigated. Detailed analysis is performed to gain a better understanding of the fundamentals of fluid mixing and interface condensation.

Lin, Chin-Shun

1991-01-01

158

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation  

NASA Astrophysics Data System (ADS)

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear-free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to solve the nondimensional form of steady state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of above stated parameters on the condensation Nusselt and Stanton numbers which characterize the steady-state interface condensation process are investigated. Detailed analysis to gain a better understanding of the fundamentals of fluid mixing and interface condensation is performed.

Lin, Chin-Shun

1989-04-01

159

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation  

NASA Astrophysics Data System (ADS)

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear-free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to solve the nondimensional form of steady state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of above stated parameters on the condensation Nusselt and Stanton numbers which characterize the steady-state interface condensation process are investigated. Detailed analysis to gain a better understanding of the fundamentals of fluid mixing and interface condensation is performed.

Lin, Chin-Shun

1989-06-01

160

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

NASA Astrophysics Data System (ADS)

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 found to be four times lower on average compared to measurements at static surfaces. Data acquisition rates in jet experiments are also generally higher than for static liquids due to reduced problems with splashing effects. The use of LIBS in jets has also been investigated for quantitative analysis of used lubricants. A number of contaminants have been measured in a set of used engine oils and the results compared to analysis via ICP-AES, where a good correlation is obtained.

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

2005-08-01

161

Status of the liquid-metal-jet-anode electron-impact x-ray source  

NASA Astrophysics Data System (ADS)

We have demonstrated a new electron-impact hard-x-ray source based on a liquid-metal-jet anode in a proof-of-principle experiment. Initial calculations show that this new anode concept potentially allows a >100x increase in source brightness compared to today's compact hard-x-ray sources. In this paper we report on the scale up of the system to medium electron-beam power resulting in a brightness comparable to current state-of-the-art sources. The upgraded system combines a ~20-?m diameter liquid-tin jet operating at ~60 m/s with a 50 kV, 600 W electron beam focused to ~150 ?m FWHM. We describe the properties of the current system, experimental results, as well as a brief discussion of key issues for future high-power scaling.

Otendal, Mikael; Tuohimaa, Tomi; Hemberg, Oscar E.; Hertz, Hans M.

2004-11-01

162

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

NASA Astrophysics Data System (ADS)

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A ~30 W, 50 kV electron gun is focused onto the ~20 m/s, 30 ?m diameter liquid-gallium-jet anode to produce an ~10 ?m full width at half maximum x-ray spot. The peak spectral brightness is >2×1010 photons/(s mm2 mrad2×0.1% 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.

2008-01-01

163

Sub-cooled and flashing liquid jets and droplet dispersion I. Overview and model implementation\\/validation  

Microsoft Academic Search

Many accidents involve two-phase releases of hazardous chemicals into the atmosphere. This paper describes the results of a third phase of a Joint Industry Project (JIP) on liquid jets and two-phase droplet dispersion. The aim of the project is to increase the understanding of the behaviour of sub-cooled non-flashing and superheated flashing liquid jets, and to improve the prediction of

Henk W. M. Witlox; Mike Harper; Adeyemi Oke; Philip J. Bowen; Peter Kay

2010-01-01

164

FLASHING LIQUID JETS AND TWO-PHASE DROPLET DISPERSION  

Microsoft Academic Search

Loss of containment often results in flashing releases of hazardous chemicals into the atmosphere. Rainout of these chemicals reduces airborne concentrations, but can also lead to extended cloud duration because of re-evaporation of the rained-out liquid. Therefore for hazard assessment one must use models which accurately predict both the amount of rainout and its rate of re-evaporation. However, the findings

Henk Witlox; Mike Harper; Phil Bowen; Vincent Cleary

165

Flashing liquid jets and two-phase droplet dispersion  

Microsoft Academic Search

Loss of containment often results in flashing releases of hazardous chemicals into the atmosphere. Rainout of these chemicals reduces airborne concentrations, but can also lead to extended cloud duration because of re-evaporation of the rained-out liquid. Therefore, for hazard assessment one must use models which accurately predict both the amount of rainout and its rate of re-evaporation. However, the findings

Henk Witlox; Mike Harper; Phil Bowen; Vincent Cleary

2007-01-01

166

Flashing liquid jets and two-phase droplet dispersion  

Microsoft Academic Search

The large-scale release of a liquid contained at upstream conditions above its local atmospheric boiling point is a scenario often given consideration in process industry risk analysis. Current-hazard quantification software often employs simplistic equilibrium two-phase approaches.Scaled water experiments have been carried out measuring droplet velocity and droplet size distributions for a range of exit orifice aspect ratios (L\\/d) and conditions

Vincent Cleary; Phil Bowen; Henk Witlox

2007-01-01

167

Status of the liquid-xenon-jet laser-plasma source for EUV lithography  

NASA Astrophysics Data System (ADS)

The liquid-xenon-jet laser-plasma source is one of the extreme-ultraviolet (EUV) source technologies under development for EUV lithography. This paper presents some recent improvements of the technology, including the ability to operate a stable plasma at a distance of 50 mm from the nozzle, the first positive mirror-lifetime results, and improved laser-to-EUV conversion efficiency of 0.75 percent at lambda equals 13.45 nm.

Hansson, Bjoern A.; Rymell, Lars; Berglund, Magnus; Hemberg, Oscar E.; Janin, Emmanuelle; Thoresen, Jalmar; Mosesson, Sofia; Wallin, Johan; Hertz, Hans M.

2002-07-01

168

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

Microsoft Academic Search

The fluid mechanics of the deposition of micron liquid (olive oil) droplets on a glass wall in an impinging turbulent air\\u000a jet is studied experimentally. The spatial patterns of droplets deposited on a wall are measured by using luminescent oil\\u000a visualization technique, and the statistical data of deposited droplets are obtained through microscopic imagery. Two distinct\\u000a rings of droplets deposited

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

2010-01-01

169

Transient Conjugate Heat Transfer During Free Liquid Jet Impingement on a Rotating Solid Disk  

Microsoft Academic Search

This article presents the transient conjugate heat transfer characterization of a free liquid jet impinging on a rotating solid disk of finite thickness and radius. Calculations were done for a range of Reynolds number (500–1400), Ekman number (6.62 × 10–?), disk thicknesses to nozzle diameter ratio (0.17–1.67), and solid to fluid thermal conductivity ratio (36.91–697.56) using water as the coolant. It was

Muhammad M. Rahman; Jorge C. Lallave

2009-01-01

170

A Comprehensive Study of Conjugate Heat Transfer During Free Liquid Jet Impingement on a Rotating Disk  

Microsoft Academic Search

The aim of this computational study is to characterize convective heat transfer for a free liquid jet impinging on a rotating and uniformly heated solid disk of finite thickness and radius. Calculations are done for a number of disk materials and working fluids covering a range of Reynolds number (445–1,800), Ekman number (2.21 × 10–2.65 × 10), nozzle-to-target spacing (? = 0.55–5.0), disk thicknesses-to-nozzle diameter ratio

Muhammad M. Rahman; Jorge C. Lallave

2007-01-01

171

Air entrainment by contact lines of a solid plate plunged into a viscous fluid.  

PubMed

The entrainment of air by advancing contact lines is studied by plunging a solid plate into a very viscous liquid. Above a threshold velocity, we observe the formation of an extended air film, typically 10 microns thick, which subsequently decays into air bubbles. Exploring a large range of viscous liquids, we find an unexpectedly weak dependence of entrainment speed on liquid viscosity, pointing towards a crucial role of the flow inside the air film. This induces a striking asymmetry between wetting and dewetting: while the breakup of the air film strongly resembles the dewetting of a liquid film, the wetting speeds are larger by orders of magnitude. PMID:23003149

Marchand, Antonin; Chan, Tak Shing; Snoeijer, Jacco H; Andreotti, Bruno

2012-05-18

172

Air Entrainment by Contact Lines of a Solid Plate Plunged into a Viscous Fluid  

NASA Astrophysics Data System (ADS)

The entrainment of air by advancing contact lines is studied by plunging a solid plate into a very viscous liquid. Above a threshold velocity, we observe the formation of an extended air film, typically 10 microns thick, which subsequently decays into air bubbles. Exploring a large range of viscous liquids, we find an unexpectedly weak dependence of entrainment speed on liquid viscosity, pointing towards a crucial role of the flow inside the air film. This induces a striking asymmetry between wetting and dewetting: while the breakup of the air film strongly resembles the dewetting of a liquid film, the wetting speeds are larger by orders of magnitude.

Marchand, Antonin; Chan, Tak Shing; Snoeijer, Jacco H.; Andreotti, Bruno

2012-05-01

173

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

NASA Astrophysics Data System (ADS)

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 its line-of-sight nature, which can create overlapped objects/interfaces on the X-ray images.

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

2011-09-01

174

Joint statistics between velocity and reactive scalar in a turbulent liquid jet with a chemical reaction  

NASA Astrophysics Data System (ADS)

Joint statistics between the velocity and the concentration of reactive species are experimentally investigated in a planar liquid jet with a second-order chemical reaction A + B ? R. Reactant species A and B are premixed in a jet flow and a main flow, respectively. An optical fibre probe based on light absorption spectrometry is used to measure the instantaneous concentrations of reactive species. The stream-wise velocity and the concentrations of reactive species are simultaneously measured by combining the optical fibre probe with I-type hot-film anemometry, and we investigate the influence of the chemical reaction on correlation coefficients, joint probability density functions and cospectra of u and ?i, where u is the stream-wise velocity fluctuation and ?i is the concentration fluctuation of species i. The results show that the absolute value of the correlation coefficient between u and ?B becomes small owing to the chemical reaction, whereas that between u and ?A becomes large on the jet centreline. It is also shown that the influence of the chemical reaction on the cospectrum of u and ?i in the upstream region and near the jet centreline is different from that in the downstream region and the outer edge of the flow.

Watanabe, Tomoaki; Sakai, Yasuhiko; Nagata, Kouji; Terashima, Osamu

2013-07-01

175

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

176

Small-animal tomography with a liquid-metal-jet x-ray source  

NASA Astrophysics Data System (ADS)

X-ray tomography of small animals is an important tool for medical research. For high-resolution x-ray imaging of few-cm-thick samples such as, e.g., mice, high-brightness x-ray sources with energies in the few-10-keV range are required. In this paper we perform the first small-animal imaging and tomography experiments using liquid-metal-jet-anode x-ray sources. This type of source shows promise to increase the brightness of microfocus x-ray systems, but present sources are typically optimized for an energy of 9 keV. Here we describe the details of a high-brightness 24-keV electron-impact laboratory microfocus x-ray source based on continuous operation of a heated liquid-In/Ga-jet anode. The source normally operates with 40 W of electron-beam power focused onto the metal jet, producing a 7×7 ?m2 FWHM x-ray spot. The peak spectral brightness is 4 × 109 photons / ( s × mm2 × mrad2 × 0.1%BW) at the 24.2 keV In K? line. We use the new In/Ga source and an existing Ga/In/Sn source for high-resolution imaging and tomography of mice.

Larsson, D. H.; Lundström, U.; Westermark, U.; Takman, P. A. C.; Burvall, A.; Arsenian Henriksson, M.; Hertz, H. M.

2012-02-01

177

Target optimization of a water-window liquid-jet laser-plasma source  

NASA Astrophysics Data System (ADS)

We optimize the water-window x-ray flux and debris deposition for a liquid-jet laser plasma source by varying both the target diameter and the jet material. For two target liquids, methanol and ethanol, measurements of the ?=3.37 nm C VI x-ray flux and the debris deposition rates are presented as function of the jet diameter. It is shown that the effective carbon debris deposition is more than 1 order of magnitude smaller for methanol, while the x-ray flux is reduced only ~40%. The reduction in carbon debris deposition may be explained by reactive ion etching by oxygen from the plasma. Thus, the methanol water-window source may be operated at a 5-10× higher flux without increasing the debris deposition. The optimization potentially allows a reduction of the exposure time of compact soft x-ray microscopy or other water-window applications based on such sources without increasing damage to sensitive x-ray optics.

de Groot, J.; Hemberg, O.; Holmberg, A.; Hertz, H. M.

2003-09-01

178

Energy dissipation mechanisms in wave breaking processes: Spilling and highly aerated plunging breaking events  

NASA Astrophysics Data System (ADS)

The breaking of free surface waves is investigated numerically via a Navier-Stokes model for the two-fluids flow of air and water. Third order Stokes waves in a periodic domain are simulated. The fundamental wavelength is 27 cm, whereas the initial steepness varies from low values, leading to regular wave trains, up to artificially steep wave trains yielding plunging breaking events. Attention is focused on the early stage of the breaking, when most of the energy is dissipated. The energy content in air, the fraction associated to surface tension effects, the viscous dissipation in water, and the work done against the pressure field are analyzed in order to distinguish the different contributions to the dissipation. Vorticity fields and dissipation contours are also presented. In the spilling case, the extra energy content with respect to the steepest nonbreaking case focusses into the breaking region and is gradually dissipated. Once the extra energy has been dissipated, the resulting wave matches the steepest nonbreaking solution. In the plunging case, an important role is played by the air entrainment. A fraction between 10 to 35% of the energy dissipated by the breaking is spent in entraining the air cavity, and most of it is dissipated by viscous effects when the cavity collapses. The phenomenon is clearly highlighted by sequences of vorticity and dissipation contours. The circulation and the area of the cavity generated by the plunging of the jet are provided, and parametric dependencies are proposed.

Iafrati, A.

2011-07-01

179

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

NASA Astrophysics Data System (ADS)

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 (?=2.48 nm and ?=2.88 nm) is 1.0×1012 photons/(pulse×sr×line). The source diameter is ~20 ?m (full width at half maximum) and the spatial stability is better than +/-2 ?m. Within an area with uniformity of 20%, the average source brightness is 4×108 photons/(pulse×sr×?m2×line), 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.

2005-04-01

180

Effect of Liquid Viscosity on a Liquid Jet Produced by the Collapse of a Laser-Induced Bubble near a Rigid Boundary  

NASA Astrophysics Data System (ADS)

The collapse of a laser-induced cavitation bubble near a rigid boundary and its dependence on liquid (kinematic) viscosity are investigated experimentally by fiber-coupling optical beam deflection (OBD). Cavitation bubble tests are performed using a mixture of glycerin and water of various concentrations, and the viscosity ranges from 1.004× 10-6 to 51.30× 10-6 m2/s. Combining the detection principles of this detector with a widely used laser ablation model, actual liquid-jet impact forces are presented for the mentioned viscosity range. In addition, based on the model of a collapsing bubble, some characteristic parameters, such as bubble lifetime, the maximum bubble radius, and liquid-jet impact pressure, are also obtained as a function of liquid viscosity. The main conclusion is that the liquid jet is a dominant factor in cavitation damage and can be modified by liquid viscosity. A high viscosity reduces the liquid-jet impact force and cavitation erosion markedly. The mechanism of the liquid viscosity effect on cavitation erosion has also been discussed.

Liu, Xiu-mei; He, Jie; Lu, Jian; Ni, Xiao-wu

2009-01-01

181

Oral and plunging ranulas: What is the most effective treatment?  

Microsoft Academic Search

Objectives\\/Hypothesis: Preferred treatment of oral\\/plunging ranulas remains controversial. We pres- ent our experience with ranulas at the University of North Carolina (UNC) and review the literature. Methods: Retrospective review. From 1990 to 2007, 16 oral ranulas and 10 plunging ranulas were treated at UNC. Combining the UNC series with the literature identified 864 cases for review. An online survey was

Mihir R. Patel; Allison M. Deal; William W. Shockley

2009-01-01

182

Laboratory study of plunging wave impacts on vertical cylinders  

Microsoft Academic Search

The characteristics of pressures associated with plunging wave impacts on a vertical cylinder are presented. Despite a high variability in the peak pressures, spatial distributions of the impact pressure time histories, both in the vertical direction and around the seaward front of the cylindrical surface, are found to vary systematically for a range of cylinder locations in the wave plunging

Eng-Soon Chan; Hin-Fatt Cheong; Boon-Cheng Tan

1995-01-01

183

On the ignition of turbulent liquid fuel spray jets using direct numerical simulation  

NASA Astrophysics Data System (ADS)

Direct numerical simulation is used to simulate the ignition of the two-dimensional liquid fuel spray jets. The carrier fluid is solved using a compressible code with a fourth-order explicit Runge-Kutta scheme. The Lagrangian method is used to track the liquid fuel spray droplets. A chemistry mechanism for n-heptane fuel with 33 species and 65 reactions is adopted to describe the chemical reactions. The objective is to investigate the effect of mixing and evaporation cooling on the ignition and combustion processes. Some important parameters such as temperature, equivalence rate, heat release rate and the scalar dissipation rate are examined. From some samples of the results, we found that ignition first occurs at the edge of the liquid spray jet where the equivalence ratio is about 0.5 and the scalar dissipation rate is less 1.0 (1/s). In addition, for two initial spray droplet radiuses of 10 and 20 macron, the 20 macron case ignites earlier since the evaporation cooling is less than in the 10 macron case.

Wang, Yunliang

2005-11-01

184

Studies of interface deformations in single- and multi-layered liquid baths due to an impinging gas jet  

NASA Astrophysics Data System (ADS)

An impinging gas jet on a molten bath having a slag layer on top is encountered in various metal processing operations. The impinging region was studied using a physical model consisting of an air jet and water bath. Kerosene and corn oil were used as the second layer to investigate the role of the slag layer properties on interface shape and bath circulation. The interface shapes were measured both photographically and by using a surface-tracking resistance probe. The limiting condition at which the jet breaks through the kerosene or corn oil layer and reaches the water layer was determined experimentally. A phenomenological model for the prediction of penetration depth is developed for both short and long jet heights for liquid baths with and without a second liquid layer on top.

Qian, F.; Mutharasan, R.; Farouk, B.

1996-12-01

185

Low-pressure flashing mechanisms in iso-octane liquid jets  

NASA Astrophysics Data System (ADS)

This paper examines a flashing liquid regime that takes place at very high ratios of injection to discharge pressures in flow restrictions. Typically, the flashing phenomenon has been observed in laboratory experiments where a liquid flows through a short nozzle into a low-pressure chamber at a pressure value considerably lower than the liquid saturation pressure at the injection temperature. By using two visualization techniques, the schlieren and the back-lighting methods, it was possible to identify some compressible phenomena associated with the liquid flashing process from the nozzle exit section. The schlieren method was used to capture the image of a shock-wave structure surrounding a liquid core from which the phase change takes place, and the optical technique allowed us to observe the central liquid core itself. The work corroborates previous physical descriptions of flashing liquid jets to explain an observed choking behaviour as well as the presence of shock waves. According to the present analysis, flashing takes place on the surface of the liquid core through an evaporation wave process, which results from a sudden liquid evaporation in a discontinuous process. Downstream of the evaporation discontinuity, the two-phase flow reaches very high velocities, up to the local sonic speed that typically occurs at high expansion conditions, as inferred from experiments and the physical model. That sonic state is also a point of maximum mass flow rate and it is known as the Chapman Jouguet condition. The freshly sonic two-phase flow expands freely to increasing supersonic velocities and eventually terminates the expansion process through a shock-wave structure. This paper presents experimental results at several test conditions with iso-octane.

Vieira, M. M.; Simões-Moreira, J. R.

186

Investigation of laser-induced breakdown spectroscopy of a liquid jet  

SciTech Connect

We investigate the feasibility of laser-induced breakdown spectroscopy for determination of heavy metal Pb in a Pb(NO3)2 aqueous solution by using a simple homemade vertical jet device and nanosecond laser pulses. Key experimental parameters that affect the analytical performance, such as delay of the time of observation, laser pulse energy, and liquid flow rate are optimized for the best limit of detection (LOD). The LOD was determined using Pb I emission at 405.781 nm, and after optimization, the 3{sigma} LOD was found to be at the level of 60 ppm.

Feng Yuan; Yang Jiajun; Fan Jianmei; Yao Guanxin; Ji Xuehan; Zhang Xianyi; Zheng Xianfeng; Cui Zhifeng

2010-05-01

187

Flow visualization of Taylor-mode breakup of a viscous liquid jet  

NASA Astrophysics Data System (ADS)

We recently reported a new spray technique called ultrasound-modulated two-fluid (UMTF) atomization and the pertinent ``resonant liquid capillary wave (RLCW) theory'' based on linear models of Taylor-mode breakup of capillary waves. In this article, flow visualizations of liquid jets near the nozzle tip are presented to verify the central assumption of the RLCW theory that the resonant liquid capillary wave in UMTF atomization is initiated by the ultrasound at the nozzle tip. Specifically, a bright band beneath the nozzle tip was seen in ultrasonic and UMTF atomization separately, but not in two-fluid atomization. The bright band can be attributed to scattering of laser light sheet by the capillary waves generated by the ultrasound on the intact liquid jet. As the capillary wave travels downstream in the direction of airflow, it is amplified by the air blowing around it and eventually collapsed into drops. Therefore, the jet breakup time can be determined by dividing the measured band length with the capillary wave velocity. The breakup times thus determined for water and glycerol/water jets are twice the values predicted by the modified Taylor's model with a sheltering parameter, and are one order of magnitude shorter than those in conventional two-fluid atomization. Furthermore, the images of the spray in the proximity of the nozzle tip obtained by 30 ns laser pulses are consistent with the drop sizes obtained 2.3-6 cm downstream from the nozzle tip by 13 s time average of continuous laser light. Also reported in this article is the good agreement between the measured viscosity effects on the drop-size and size distribution in UMTF atomization and those on the relative amplitude growth rates of capillary waves at different wavelengths predicted by Taylor's model as a result of its inclusion of higher order terms other than the first in viscosity. These new findings have led to the conclusion that UMTF atomization occurs via Taylor-mode breakup of capillary waves; secondary atomization and drop coalescence are negligible. Further, UMTF atomization offers a means to control the drop-size and size distribution of two-fluid atomization for uniform drop formation.

Tsai, Shirley C.; Luu, Patrick; Tam, Patrick; Roski, Gerald; Tsai, Chen S.

1999-06-01

188

Vapor condensation on liquid surface due to laminar jet-induced mixing: The effects of system parameters  

NASA Astrophysics Data System (ADS)

The effects of system parameters on the interface condensation rate in a laminar jet induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a slightly subcooled jet discharged from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The jet velocity is selected to be low enough such that the free surface is approximately flat. The effect of vapor superheat is assumed to be negligible. Therefore, the interface condensation rate can be determined from the resulting temperature field in the liquid region alone. The nondimensional form of the steady state conservation equations are solved by a finite difference method for various system parameters including liquid height to tank diameter ratio, tank to jet diameter ratio, liquid inflow to outflow area ratio, and a heat leak parameter which characterizes the uniform wall heat flux. Detailed analyses based on the numerical solutions are performed and simplified equations are suggested for the prediction of condensation rate.

Lin, Chin-Shun; Hasan, Mohammad M.

1989-01-01

189

Vapor condensation on liquid surface due to laminar jet-induced mixing - The effects of system parameters  

NASA Astrophysics Data System (ADS)

The effects of system parameters on the interface condensation rate in a laminar jet induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a slightly subcooled jet discharged from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The jet velocity is selected to be low enough such that the free surface is approximately flat. The effect of vapor superheat is assumed to be negligible. Therefore, the interface condensation rate can be determined from the resulting temperature field in the liquid region alone. The nondimensional form of the steady state conservation equations are solved by a finite difference method for various system parameters including liquid height to tank diameter ratio, tank to jet diameter ratio, liquid inflow to outflow area ratio, and a heat leak parameter which characterizes the uniform wall heat flux. Detailed analyses based on the numerical solutions are performed and simplified equations are suggested for the prediction of condensation rate.

Lin, Chin-Shun; Hasan, Mohammad M.

1990-01-01

190

Efficiency and pressure recovery in hydraulic jet pumping of two-phase gas/liquid mixtures  

SciTech Connect

Hydraulic jet pumping of gas/liquid mixtures was studied experimentally, and a mathematical model is proposed to extend the standard single-phase model for predicting efficiency and pressure recovery to suction fluids with gas/liquid ratios up to 2.200 scf/STB. The experimental program comprises 616 low-pressure tests in a plastic model pump designed for flow visualization and measurement of pressure profile along the throat and diffuser, and 373 high-pressure tests on a stock pump. For the high-pressure tests, power fluid was supplied at 200 to 3,000 psi and at 200 to 860 B/D; air was supplied from 0 to 185 Mscf/D. Discharge pressures ranged from 800 to 2,000 psi.

Jlao, B.; Blals, R.N.; Schmidt, Z. (Tulsa Univ., OK (USA))

1990-11-01

191

Debris characteristics and mitigation of a laser plasma tin-contained liquid jet/droplet targets  

NASA Astrophysics Data System (ADS)

We realized a laser-plasma EUV target, which satisfied the high EUV CE and the debris suppression simultaneously by using low-concentration liquid jet/droplet targets containing tin oxides and chlorides. Plasma regulation by double pulse irradiation improved the EUV CE. In terms of the debris emissions, we reduced the amount of the deposited tin oxide by applying in situ heat and high-energy photons onto a witness plate. These active debris suppression resulted in the decrease of the deposition rate and deoxidation of the debris, respectively. The use of tin chloride liquid target also realized a well-balanced debris behavior, where deposited debris was cleaned by chlorine atoms or ions, resulting in an approximately zero deposition rate.

Kaku, Masanori; Touge, Shunsuke; Katto, Masahito; Kubodera, Shoichi

2009-03-01

192

Characteristics of free-surface wave on high-speed liquid lithium jet for IFMIF  

NASA Astrophysics Data System (ADS)

The characteristics of the surface waves on a high-speed liquid lithium wall jet were examined in a Li circulation loop at Osaka University for the International Fusion Materials Irradiation Facility (IFMIF). Surface fluctuations were measured by a contact-type liquid level sensor at 175 mm downstream from the nozzle exit, which corresponds to the deuteron beam's axis in the IFMIF, and observed with a high-speed video (HSV) camera. Both the observation and measurement results indicated that the surface fluctuations were composed of various scale turbulent fluctuations. The measurement results especially showed good agreement with the log-normal distribution which is one of the turbulent intermittency theories. The dominant wavelength was found to be shorter with increase in the flow velocity, and reached approximately 4 mm at the velocity of 15 m/s, which gave close agreement with the visually observed wavelength.

Kanemura, Takuji; Yoshihashi-Suzuki, Sachiko; Kondo, Hiroo; Sugiura, Hirokazu; Yamaoka, Nobuo; Ida, Mizuho; Nakamura, Hiroo; Matsushita, Izuru; Muroga, Takeo; Horiike, Hiroshi

2011-10-01

193

Characterization of a liquid-xenon-jet laser-plasma extreme-ultraviolet source  

NASA Astrophysics Data System (ADS)

A liquid-xenon-jet laser-plasma source for extreme-ultraviolet (EUV) and soft-x-ray generation has been characterized. Being a source candidate for EUV lithography (EUVL), we especially focus on parameters important for the integration of the source in EUVL systems. The deep-ultraviolet (DUV) out-of-band radiation (?=120-400 nm) was quantified, to within a factor of two, using a flying-circus tool together with a transmission-grating spectrograph resulting in a total DUV conversion efficiency (CE) of ~0.33%/2?sr. The size and the shape of the xenon plasma was investigated using an in-band-only EUV microscope, based on a spherical Mo/Si multilayer mirror and a charge-coupled device detector. Scalability of the source size from 20-270 ?m full width at half maximum was shown. The maximum repetition-rate sustainable by the liquid-xenon-jet target was simulated by a double-pulse experiment indicating feasibility of >17 kHz operation. The xenon-ion energy distribution from the plasma was determined in a time-of-flight experiment with a Faraday-cup detector showing the presence of multi-kilo-electron-volt ions. Sputtering of silicon witness plates exposed to the plasma was observed, while a xenon background of >1 mbar was shown to eliminate the sputtering. It is concluded that the source has potential to meet the requirements of future EUVL systems.

Hansson, B. A. M.; Hemberg, O.; Hertz, H. M.; Berglund, M.; Choi, H.-J.; Jacobsson, B.; Janin, E.; Mosesson, S.; Rymell, L.; Thoresen, J.; Wilner, M.

2004-06-01

194

Measurements of Local Fluid Velocities in an Axisymmetric, Free Liquid Jet Impinging on a Flat Plate  

NASA Astrophysics Data System (ADS)

This study characterized the mean and fluctuating parts of the radial component of the local velocity throughout the impingement region and radially spreading liquid layer of an impinging liquid jet striking a smooth flat plate. Velocities were measured with an LDV in the impingement region and in the radial-flow layer. In the impingement region, mean velocities were found to vary linearly with the radial coordinate. For jets formed from a fully developed pipe flow, the dimensionless radial velocity gradient was independent of nozzle diameter and Reynolds number, and varied linearly with distance from the impingement plate. Although the flow field near the stagnation point differed from the flow field of a laminar, infinite stagnation flow, it was shown that this made little difference in the boundary layer solution. Free surface velocity measurements on the radial-flow layer collapsed around a band when plotted in dimensionless coordinates. Radial velocity profiles across the layer were measured and found to differ from previous analytic expressions for the velocity profile close to the stagnation region. Corresponding measurements of the impingement region velocity and heat transfer were made for matched experimental configurations in order to assess the effects of turbulence and velocity gradient on the heat transfer. It was found that the velocity gradient was more important than the radial turbulent fluctuations for the heat transfer.

Stevens, James W.

195

Hydraulic Jet Flow of an Ideal Liquid and Gas-Liquid Mixtures.  

National Technical Information Service (NTIS)

The report contains articles on the performance of a reaction engine with an ejector shroud, the numerical solution to the problem of cooling a hot gas bubble in liquid, and the theory of gas-hydraulic propulsion engines.

G. V. Logvinovich V. M. Ivchenko I. M. Chernyi

1972-01-01

196

Ultrasound-modulated twin-fluid atomization of a liquid jet.  

PubMed

A resonant liquid capillary wave theory which extends Taylor's dispersion relation to include the sheltering effect of liquid surface inclination caused by air flow is presented. The resulting dispersion curves are compared to new experimental results of how drop-size and size distributions vary with surface tension and air velocity in both airblast and ultrasound-modulated twin-fluid atomization of liquids with a constant kinematic viscosity of 2 cSt. Good agreements between the theoretical predictions of relative growth rates of the capillary waves and the experimental results of drop-size and size distributions led to the conclusion that Taylor-mode breakup of capillary waves plays a very important role in twin-fluid (airblast) atomization of a liquid jet. Thus, the ultrasound-modulated twin-fluid atomization not only verifies the capillary wave mechanism but also provides a means for controlling the drop-size and size distributions in twin-fluid atomization, which has a variety of applications in fuel combustion, spray drying, and spray coating. PMID:18238407

Tsai, S C; Luu, P; Childs, P; Tsai, C S

1999-01-01

197

A novel method of drug delivery for fibrinolysis with Ho:YAG laser-induced liquid jet.  

PubMed

Two of the problems inherent in the treatment of cerebral emboli are the narrow therapeutic time window and the severe side effects of fibrinolytic drugs. Thus, it is necessary to develop a new method of removing a cerebral thrombus more rapidly and with smaller quantities of fibrinolytics. The behaviour of a bubble formed by holmium (Ho):YAG laser irradiation in a capillary tube filled with pure water was observed at various stand-off distances (L; distance between the end of optical fibre and the capillary exit). Subsequently, a liquid-jet generator was created by insertion of an optical fibre (core diameter: 0.6 mm) into a catheter (6 Fr) filled with pure water, and a pulsed Ho:YAG laser (pulse duration time=350 micros, laser energy=230 mJ/pulse) was used to irradiate the optical fibre. The maximum penetration depth, into a gelatin artificial thrombus, of a liquid jet generated with this device was measured for various stand-off distances. Additionally, the phenomenon and the pressure around the catheter exit were captured via shadowgraph and PVDF needle hydrophone, respectively. The laser-induced bubble in the capillary tube grew rapidly in the direction of propagation and generated a liquid jet. The maximum penetration depth of this liquid jet into an artificial thrombus increased in proportion to L and reached a maximum value (9 mm) when L was around 13 mm. A shock wave whose overpressure at a point 4 mm away from the catheter exit exceeded 12 MPa was captured by shadowgraph. It was concluded that Ho:YAG laser irradiation within a water-filled catheter caused liquid jet formation, which could penetrate straight into an artificial thrombus. Hence, this jet is expected to promote fibrinolysis by means of injecting fibrinolytics deeply into the thrombus. After resolving some problems, this system will be applied to an endovascular therapy for cerebral embolisms in the near future. PMID:12181631

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

2002-01-01

198

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

199

Surgery for plunging ranula: the lesson not yet learned?  

Microsoft Academic Search

Our objective is to review our experience with treatment of plunging ranula and examine the efficacy of transoral excision\\u000a of sublingual gland as the principal treatment. This study comprises a case series with chart review. A secondary otolaryngology\\u000a service was used as the setting. Retrospective analysis of patient records was performed for a series of 95 consecutive cases\\u000a of plunging

Sumit Samant; Randall P. Morton; Zahoor Ahmad

200

Plunging ranula of the submandibular area.  

PubMed

The term "ranula" is used to describe a diffuse swelling in the floor of the mouth caused by either a mucous extravasation or, less commonly, a mucous retention cyst derived from the major sublingual or submandibular salivary glands. The most common presentation of ranula is a painless, slow-growing, soft, and movable mass located in the floor of the mouth. Ranula may be simple or plunging. Simple ranula often present as masses in the floor of the mouth, limited to the mucous membranes. Diving ranulas extend through the facial plans, usually posterior to the mylohyoid muscle into the neck, and present as cervical masses. Thyroglossal duct cyst, branchial cleft cyst, cystic hygroma, submandibular sialadenitis, intramuscular hemangioma, cystic or neoplastic thyroid disease might be included in differential diagnosis. A variety of surgical procedures have been quoted in the literature ranging from marsupialization, excision of the ranula, sclerotherapy, and excision of the sublingual gland. The recurrence rate varies according to the procedure performed. PMID:23372589

Sheikhi, Mahnaz; Jalalian, Faranak; Rashidipoor, Roghayeh; Mosavat, Farzaneh

2011-12-01

201

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

NASA Astrophysics Data System (ADS)

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 ?m in diameter and the electron-beam power density is up to ~210 kW/mm2, 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.

2007-01-01

202

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

203

Numerical Simulation and Experimental Study of Liquid-Solid Two-Phase Flow in Nozzle of DIA Jet  

NASA Astrophysics Data System (ADS)

The velocity of abrasive particles at the nozzle exit of Direct Injection Abrasive (DIA) Jet is a key factor affecting cutting capacity of jet. The powerful Computational Fluid Dynamics (CFD) analysis software Fluent is applied to numerical simulation of liquid-solid two-phase flow in the hard alloy nozzle of different cylindrical section length under a certain conditions. The optimum ratio of diameter to length is obtained when the particle velocities are the largest at the nozzle exit. The rule of velocity distribution of liquid-solid two-phase flow of the optimum nozzle is analyzed. The numerical control cutting machine tool of DIA Jet is adopted to finish cutting experiments on different variety of materials. The analytic results of experiments verify the results of numerical simulation.

Hu, Guihua; Zhu, Wenhua; Yu, Tao; Yuan, Jin

204

A Sub-model of a Reacting Gas-Liquid Jet as a Tool for Better Simulation of Liquid Fuel Combustion in Fluidized Bed  

Microsoft Academic Search

1. Abstract The paper presents and discusses a sub-model of a horizontal, reacting jet flare downstream from a nozzle discharging liquid fuel into a fluidized bed combustor. It is a further achievement towards a more thorough description of fundamental mechanisms governing the liquid fuel combustion in bubbling fluidized bed combustors (FBC) that operate in a temperature range (i.e., 650-800°C) lower

L. Ferrante; M. Miccio

205

Characterisation and aerosolisation of mannitol particles produced via confined liquid impinging jets.  

PubMed

Mannitol particles, produced by spray drying (SD), have been used commercially (Aridol) in bronchial provocation test. In this study, we propose an alternative method to produce inhalable mannitol powders. The elongated mannitol particles (number median length 4.0microm, and axial ratio of 3.5) were prepared using a confined liquid impinging jets (CLIJs) followed by jet milling (JM). Spray dried and jet milled raw mannitol particles were compared in an attempt to assess the performance of the particles produced by the new method. Aerosol performance of the three different powders (CLIJ, SD, and JM) was relatively poor (fine particle fraction or FPF(loaded) below 15%) when dispersed by the Rotahaler. Dispersion through the Aeroliser led to better aerosol performance of the CLIJ mannitol (FPF(loaded) 20.3%), which is worse than the JM (FPF(loaded) 30.3%) and SD mannitol particles (FPF(loaded) 45.7%) at 60 L/min, but comparable (FPF(loaded) 40.0%) with those of the JM (FPF(loaded) 40.7%) and SD (FPF(loaded) 45.5%) powders at 100L/min. Hence, the optimum use of these elongated mannitol particles can be achieved at increased air flow with a more efficient inhaler. In addition to crystallinity, morphology, and particle size distribution, the surface energies of these powders were measured to explain the differences in aerosol performance. A major advantage of using the CLIJ method is that it can be scaled up with a good yield as the precipitate can be largely collected and recovered on a filter, compared with spray drying which has a low collection efficiency for fine particles below 2microm. PMID:18848874

Tang, P; Chan, H-K; Chiou, H; Ogawa, K; Jones, M D; Adi, H; Buckton, G; Prud'homme, R K; Raper, J A

2008-09-21

206

Sub-cooled and flashing liquid jets and droplet dispersion II. Scaled experiments and derivation of droplet size correlations  

Microsoft Academic Search

This paper describes the results of the first stage of Phase III of a Joint Industry Project (JIP) on liquid jets and two-phase droplet dispersion. This stage included scaled experiments for water, gasoline, and cyclohexane for a range of superheats and nozzles with different aspect ratios. Additional experiments for butane and propane were conducted as a validation exercise and are

Peter J. Kay; Phillip J. Bowen; Henk W. M. Witlox

2010-01-01

207

Heat, Mass, and Momentum Transfer Between a High Velocity Liquid Jet and a Concentric Gas Stream in an Axisymmetric Channel.  

National Technical Information Service (NTIS)

The study began with an effort to determine whether the liquid stream entering the mixing section of an ejector-like device remained intact in a jet or atomized. The conclusions were that for the range of variables of interest the probability was that the...

J. H. Leigh S. W. Gouse

1965-01-01

208

Structure of turbulent round bubbling jet generated by premixed gas and liquid injection  

Microsoft Academic Search

An air water mixture was injected into a cylindrical water bath through a single-hole bottom nozzle to generate a vertical turbulent bubbling jet. A parameter called jet volume fraction, defined as the ratio of the air flow rate to the total flow rate of air and water, was introduced to specify the bubbling jet. The jet volume fraction was raised

M. Iguchi; K. Okita; T. Nakatani; N. Kasai

1997-01-01

209

High Fidelity Simulation of Liquid Jet in Cross-flow Using High Performance Computing  

NASA Astrophysics Data System (ADS)

High fidelity, first principles simulation of atomization of a liquid jet by a fast cross-flowing gas can help reveal the controlling physics of this complicated two-phase flow of engineering interest. The turn-around execution time of such a simulation is prohibitively long using typically available computational resources today (i.e. parallel systems with ˜O(100) CPUs). This is due to multiscale nature of the problem which requires the use of fine grids and time steps. In this work we present results from such a simulation performed on a state of the art massively parallel system available at Oakridge Leadership Computing Facility (OLCF). Scalability of the computational algorithm to ˜2000 CPUs is demonstrated on grids of up to 200 million nodes. As a result, a simulation at intermediate Weber number becomes possible on this system. Results are in agreement with detailed experiment measurements of liquid column trajectory, breakup location, surface wavelength, onset of surface stripping as well as droplet size and velocity after primary breakup. Moreover, this uniform grid simulation is used as a base case for further code enhancement by evaluating the feasibility of employing Adaptive Mesh Refinement (AMR) near the liquid-gas interface as a means of mitigating computational cost.

Soteriou, Marios; Li, Xiaoyi

2011-11-01

210

Improved Emission Uniformity from a Liquid-Jet Laser-Plasma Extreme-Ultraviolet Source  

NASA Astrophysics Data System (ADS)

Many modern compact soft-x-ray and extreme-ultraviolet (EUV) imaging systems operate with small fields of view and therefore benefit from the use of small high-brightness sources. Such systems include water-window microscopes and EUV lithography tools. We show that the photon losses in such systems can be minimized while uniformity of object-plane illumination is maintained by controlled scanning of the source. The improved collection efficiency is demonstrated both theoretically and experimentally for a scanned laser-plasma source compared with static sources. A prospective aerial image microscope and a liquid-xenon-jet laser-plasma source are offered as examples of modern imaging tools that may benefit from such scanning of the source.

Hansson, Björn A. M.; Mosesson, Sofia; Hertz, Hans M.

2004-10-01

211

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

NASA Astrophysics Data System (ADS)

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 ~6.5 ?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.

2007-08-01

212

The instability of nonlinear surface waves in an electrified liquid jet  

NASA Astrophysics Data System (ADS)

We investigate the weakly nonlinear stability of surface waves of a liquid jet. In this work, the liquids are uniformly streaming through two porous media and the gravitational effects are neglected. The system is acted upon by a uniform tangential electric field, that is parallel to the jet axis. The equations of motion are linearly treated and solved in the light of nonlinear boundary conditions. Therefore, the boundary-value problem leads to a nonlinear characteristic second-order differential equation. This characterized equation has a complex nature. The nonlinearity is kept up to the third degree. It is used to judge the behavior of the surface evolution. According to the linear stability theory, we derive the dispersion relation that accounts for the growth waves. The stability criterion is discussed analytically and a stability picture is identified for a chosen sample system. Several special cases are recovered upon appropriate data choices. In order to derive the Ginsburg-Landau equation for the general case, in the nonlinear approach, we used the method of multiple timescales with the aid of the Taylor expansion. This equation describes the competition between nonlinearity and the linear dispersion relation. As a special case for non-porous media where there is no streaming, we obtained the well-known nonlinear Schrödinger equation as it has been derived by others. The stability criteria are expressed theoretically in terms of various parameters of the problem. Stability diagrams are obtained for a set of physical parameters. We found new instability regions in the parameter space. These regions are due to the nonlinear effects.

Moatimid, Galal M.

2009-06-01

213

Modeling and simulation of fragmentation of suddenly heated liquid metal jets.  

SciTech Connect

Thermoelastic response of liquid metal targets exposed to high-volumetric-energy deposition in times shorter than the target hydrodynamic response time (i.e., sound travel time) is of interest to several research areas, including first walls of fusion reactors (especially inertially confined fusion reactors), targets for high-power accelerators such as the Spallation Neutron Source, muon collider targets, etc. Under conditions that exist in these reactors, accelerators, etc., the deposited energy is considered instant in time from the hydrodynamic point of view. Because thermal heat conduction requires a longer than instant response time for energy redistribution, only hydrodynamic phenomena should be taken into account when modeling and simulating the fragmentation of suddenly heated liquid metal jets. Sudden energy deposition causes an instant rise in temperature that leads to a corresponding rise in the thermal pressure that causes excitation of sound waves, i.e., shock waves and rarefaction waves. During this excitation of sound waves, pressure oscillates with magnitude {+-} {Delta}P that corresponds to an initial thermal pressure of tens of katm. Liquids are frequently observed to withstand significant negative pressures (hydrostatic tensile stresses). Yet, a liquid subjected to a negative pressure is metastable. The formation and behavior of cavities (empty voids) under negative pressures was previously studied. Theoretically, the obtained fracture (failure) pressure of mercury is in good agreement with experimental results. Cavitation, or spontaneous formation of cavities, in stressed liquid metal targets is of interest to engineers and physicists who operate high-power targets in fusion reactors, nuclear accelerators, and particle colliders. The problems of liquid target oscillation in the presence of large magnitudes of negative pressure, and the mechanism of fragmentation and its consequences are considered in this analysis. It is shown that a cavity coming into existence will initiate a shock wave that is actually a relaxation shock wave initiated when the stretched medium reverts to normal density from the low-density state. The nature of this relaxation wave is similar to that of the detonation wave. It is also shown that a cavity born at the high-negative-pressure stage expands permanently and does not disappear. This permanent expansion and failure to disappear is a major difference between the cavity dynamics in stretched media and the dynamics observed in the usual cavitation processes that occur when vapor bubbles collapse during a phase of increased pressure, and is the result of ''unloading'' or ''discharging'' of the medium by the relaxation shock wave initiated by the appearance of the cavity. Detailed calculations of cavity dynamics are presented for both spherical and cylindrical liquid metal target systems.

Hassanein, A.; Konkashbaev, I.

2001-06-26

214

Cryogenic liquid-jet target for debris-free laser-plasma soft x-ray generation  

NASA Astrophysics Data System (ADS)

A new target system based on a continuous cryogenic liquid jet for debris-free laser-plasma soft x-ray generation is described. The system is experimentally evaluated with liquid nitrogen as target material. With this target the photon flux is 4.5×1011 photons/(sr×pulse) from the ?=2.88 nm N VI line. Brightness and stability are also investigated for this table-top soft x-ray microscope source. The possibility to utilize other cryogenic liquids such as neon, argon, and xenon and, thus, making the system interesting for short-wavelength lithography applications, is also discussed.

Berglund, M.; Rymell, L.; Hertz, H. M.; Wilhein, T.

1998-06-01

215

Probing orbital symmetry in solution: polarization-dependent resonant inelastic soft x-ray scattering on liquid micro-jet  

NASA Astrophysics Data System (ADS)

Polarization-dependent resonant inelastic x-ray scattering is demonstrated here for liquid acetonitrile, acetone and dimethyl sulfoxide, using the liquid micro-jet technique. Selective excitation to an unoccupied orbital with a specific symmetry at the K-edge x-ray absorption of liquid samples determines the polarization-dependent emission of the occupied states. Considering the well-defined unoccupied molecular orbital configuration and utilizing the results of ab initio molecular orbital calculations, the polarization-dependent anisotropy in resonant inelastic soft x-ray scattering is discussed in a membrane-free configuration.

Dierker, B.; Suljoti, E.; Atak, K.; Lange, K. M.; Engel, N.; Golnak, R.; Dantz, M.; Hodeck, K.; Khan, M.; Kosugi, N.; Aziz, E. F.

2013-09-01

216

Nanoscale, electrified liquid jets for high-resolution printing of charge.  

PubMed

Nearly all research in micro- and nanofabrication focuses on the formation of solid structures of materials that perform some mechanical, electrical, optical, or related function. Fabricating patterns of charges, by contrast, is a much less well explored area that is of separate and growing interesting because the associated electric fields can be exploited to control the behavior of nanoscale electronic and mechanical devices, guide the assembly of nanomaterials, or modulate the properties of biological systems. This paper describes a versatile technique that uses fine, electrified liquid jets formed by electrohydrodynamics at micro- and nanoscale nozzles to print complex patterns of both positive and negative charges, with resolution that can extend into the submicrometer and nanometer regime. The reported results establish the basic aspects of this process and demonstrate the capabilities through printed patterns with diverse geometries and charge configurations in a variety of liquid inks, including suspensions of nanoparticles and nanowires. The use of printed charge to control the properties of silicon nanomembrane transistors provides an application example. PMID:20067277

Park, Jang-Ung; Lee, Sangkyu; Unarunotai, Sakulsuk; Sun, Yugang; Dunham, Simon; Song, Taeseup; Ferreira, Placid M; Alleyene, Andrew G; Paik, Ungyu; Rogers, John A

2010-02-10

217

Jet fuels potential of liquid by-products from the Great Plains Gasification Project  

SciTech Connect

Three liquid by-products from the Great Plains Gasification Project--tar oil, crude phenols, and naphtha--were evaluated as potential sources of military jet fuels. Each was used as a feedstock for catalytic hydrogenation experiments to characterize its hydrogenation behavior and to determine the properties of intermediate products at various levels of process severity. Shell 424 Ni--Mo catalyst was employed in all experiments. Tar oil experiments were conducted at 2000 psig, with liquid hourly space velocities (LHSV) of 1.00, 0.50, or 0.33, hydrogen feed ratios from 6000 standard cubic feet per barrel (scfb) to 16,000 scfb, and at temperatures from 650{degree}F (343{degree}C) to 750{degree}F (399{degree}C). Phenols experiments were conducted at 2000 psig, LHSV of 0.50 or 1.00, with a hydrogen feed ratio of 6000 scfb and at temperatures ranging from 550{degree}F (289{degree}C) to 650{degree}F (343{degree}C). Naphtha experiments were conducted at 500 psig, with LHSV of 1.00, a hydrogen feed ratio of 1500 scfb, and temperatures of 300{degree}F (149{degree}C) to 500{degree}F (260{degree}C). Five products were collected, three of which were sufficiently saturated to serve as sources for preparation of test fuel samples. 3 refs., 19 tabs.

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

1988-01-01

218

Surgery for plunging ranula: the lesson not yet learned?  

PubMed

Our objective is to review our experience with treatment of plunging ranula and examine the efficacy of transoral excision of sublingual gland as the principal treatment. This study comprises a case series with chart review. A secondary otolaryngology service was used as the setting. Retrospective analysis of patient records was performed for a series of 95 consecutive cases of plunging ranula, which presented to our department between January 2001 and February 2010. Clinical presentation, investigations, diagnosis, treatment, complications and outcome were recorded. Literature search was performed using MEDLINE and OLD MEDLINE. 81 cases of plunging ranula were treated surgically by transoral excision of sublingual gland and evacuation of ranula contents. Mean operating time was 75.3 min. Twelve patients had undergone previous surgery elsewhere. One patient in our series had a recurrence, needing excision of sublingual gland remnant. Two patients had trauma to submandibular duct requiring excision of submandibular gland. Other complications were minor and transient. Review of literature revealed many diverse methods of treating ranula, with varying results. Our series makes a substantial contribution to the number of plunging ranulas reported in the world, and supports the use of transoral sublingual gland excision as first-line treatment of plunging ranula. PMID:21328001

Samant, Sumit; Morton, Randall P; Ahmad, Zahoor

2011-02-16

219

The influence of dilution hole geometry on jet mixing  

NASA Astrophysics Data System (ADS)

The measurements conducted on the present fully annular test facility, downstream of a row of heated dilution jets injected into a confined crossflow, at a momentum flux ratio of 4, gave attention to the consistency of mixing between the jets. When heated air was supplied, the exit velocity profile across each plunged hole was significantly altered and led to the distortion of the ensuing jet's temperature distribution. Tests conducted under the same conditions with modified plunged dilution holes exhibited a significant improvement in the circumferential regularity of the temperature pattern.

Carrotte, J. F.; Stevens, S. J.

1990-01-01

220

Multi-fluid Dynamics for Supersonic Jet-and-Crossflows and Liquid Plug Rupture  

NASA Astrophysics Data System (ADS)

Multi-fluid dynamics simulations require appropriate numerical treatments based on the main flow characteristics, such as flow speed, turbulence, thermodynamic state, and time and length scales. In this thesis, two distinct problems are investigated: supersonic jet and crossflow interactions; and liquid plug propagation and rupture in an airway. Gaseous non-reactive ethylene jet and air crossflow simulation represents essential physics for fuel injection in SCRAMJET engines. The regime is highly unsteady, involving shocks, turbulent mixing, and large-scale vortical structures. An eddy-viscosity-based multi-scale turbulence model is proposed to resolve turbulent structures consistent with grid resolution and turbulence length scales. Predictions of the time-averaged fuel concentration from the multi-scale model is improved over Reynolds-averaged Navier-Stokes models originally derived from stationary flow. The response to the multi-scale model alone is, however, limited, in cases where the vortical structures are small and scattered thus requiring prohibitively expensive grids in order to resolve the flow field accurately. Statistical information related to turbulent fluctuations is utilized to estimate an effective turbulent Schmidt number, which is shown to be highly varying in space. Accordingly, an adaptive turbulent Schmidt number approach is proposed, by allowing the resolved field to adaptively influence the value of turbulent Schmidt number in the multi-scale turbulence model. The proposed model estimates a time-averaged turbulent Schmidt number adapted to the computed flowfield, instead of the constant value common to the eddy-viscosity-based Navier-Stokes models. This approach is assessed using a grid-refinement study for the normal injection case, and tested with 30 degree injection, showing improved results over the constant turbulent Schmidt model both in mean and variance of fuel concentration predictions. For the incompressible liquid plug propagation and rupture study, numerical simulations are conducted using an Eulerian-Lagrangian approach with a continuous-interface method. A reconstruction scheme is developed to allow topological changes during plug rupture by altering the connectivity information of the interface mesh. Rupture time is shown to be delayed as the initial precursor film thickness increases. During the plug rupture process, a sudden increase of mechanical stresses on the tube wall is recorded, which can cause tissue damage.

Hassan, Ezeldin A.

221

Effect of nozzle configuration on transport in the stagnation zone of axisymmetric, impinging free-surface liquid jets: Part 1turbulent flow structure  

Microsoft Academic Search

This study characterized the mean and fluctuating parts of the radial component of the local velocity in the stagnation region of an impinging, free-surface liquid jet striking a smooth flat plate. Four different nozzle exit conditions were studied, including fully developed pipe flow, a contoured nozzle, and turbulence-damped and undamped sharp-edged orifices. Liquid jet Reynolds numbers in the range 30,000

J. Stevens; Y. Pan; B. W. Webb

1992-01-01

222

Thermal management of a 3D chip stack using a liquid interface to a synthetic jet cooled spreader  

Microsoft Academic Search

The present investigation focuses on the design of a unique liquid interface thermal management solution for a 3D chip stack that is embedded within a cavity, in a heat spreader cooled by an array of synthetic jet actuators. The heat sink module was previously reported by the authors, who achieved an overall heat transfer coefficient of ~70 W\\/m2.K. The radial

Krishna Kota; Pablo Hidalgo; Yogendra Joshi; Ari Glezer

2009-01-01

223

Plunging ranula as a complication of intraoral removal of a submandibular sialolith  

Microsoft Academic Search

Mucous cysts in the submandibular region – so-called 'plunging' ranula – are relatively uncommon. We report a case of a plunging ranula that complicated excision of an intraductal sialolith of the submandibular gland.

S. Iida; M. Kogo; G. Tominaga; T. Matsuya

2001-01-01

224

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

PubMed

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 1 ms after irradiation. A shock wave induced by ignition of silver azide pellet was interacted with it at 500mus 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. PMID:20663374

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

2002-01-10

225

Characterization and Scaling of Vortex Shedding from a Plunging Plate  

NASA Astrophysics Data System (ADS)

Leading-edge and trailing-edge vortices (LEV and TEV) are investigated for a plunging flat plate airfoil at a chord Reynolds number of 10,000 while varying plunge amplitude and Strouhal number. Digital Particle Image Velocimetry is used to examine the strength and dynamics of shed vortices. Vortex strength, timing, pinch-off and trajectory are examined. By tracking the development of both the LEV and TEV in phase-locked measurements throughout the cycle and extracting the respective vortex circulation, the dimensionless circulation of both the LEV and TEV at each phase in the cycle could be determined. Guided by theoretical considerations for vorticity generation and aerodynamic theory, we will discuss the role of kinematic parameters on vortex shedding and the applicability of a scaling factor for the circulation of the shed vortex structures. Whereas a scaling parameter based on plate kinematics effectively collapses the circulation values of the shed leading-edge vortices with variation in Strouhal number, plunge amplitude, and angle of attack, it is found that the strength of the trailing-edge structures vary little with variation in plunge amplitude and angle of attack.

Eslam Panah, Azar; Buchholz, James

2011-11-01

226

The physical behavior of a gas jet injected horizontally into liquid metal  

Microsoft Academic Search

The gas fraction and bubble frequency distributions in a submerged air jet, injected horizontally into mercury, have been\\u000a measured under isothermal, nonreactive conditions for nozzle diameters of 0.325 and 0.476 cm and jet Froude numbers ranging\\u000a from 20.5 to 288. The measurements reveal that the jets expand extremely rapidly upon discharge from the nozzle with an initial\\u000a expansion angle of

G. N. Oryall; J. K. Brimacombe

1976-01-01

227

The physical behavior of a gas jet injected horizontally into liquid metal  

Microsoft Academic Search

The gas fraction and bubble frequency distributions in a submerged air jet, injected horizontally into mercury, have been measured under isothermal, nonreactive conditions for nozzle diameters of 0.325 and 0.476 cm and jet Froude numbers ranging from 20.5 to 288. The measurements reveal that the jets expand extremely rapidly upon discharge from the nozzle with an initial expansion angle of

G. N. Oryall; J. K. Brimacombe

1976-01-01

228

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

229

Inertance measurements by jet pulses in ventilated small lungs after perfluorochemical liquid (PFC) applications  

Microsoft Academic Search

Perfluorochemical liquid (PFC) liquids or aerosols are used for assisted ventilation, drug delivery, lung cancer hyperthermia and pulmonary imaging. The aim of this study was to investigate the effect of PFC liquid on the inertance (I) of the respiratory system in newborn piglets using partial liquid ventilation (PLV) with different volumes of liquid. End-inspiratory (Iin) and end-expiratory (Iex) inertance were

Gerd Schmalisch; Hans Proquitté; Mario Schmidt; Mario Rüdiger; Roland R. Wauer

2005-01-01

230

Mechanisms of bacterial inactivation in the liquid phase induced by a remote RF cold atmospheric pressure plasma jet  

NASA Astrophysics Data System (ADS)

A radio-frequency atmospheric pressure argon plasma jet is used for the inactivation of bacteria (Pseudomonas aeruginosa) in solutions. The source is characterized by measurements of power dissipation, gas temperature, absolute UV irradiance as well as mass spectrometry measurements of emitted ions. The plasma-induced liquid chemistry is studied by performing liquid ion chromatography and hydrogen peroxide concentration measurements on treated distilled water samples. Additionally, a quantitative estimation of an extensive liquid chemistry induced by the plasma is made by solution kinetics calculations. The role of the different active components of the plasma is evaluated based on either measurements, as mentioned above, or estimations based on published data of measurements of those components. For the experimental conditions being considered in this work, it is shown that the bactericidal effect can be solely ascribed to plasma-induced liquid chemistry, leading to the production of stable and transient chemical species. It is shown that HNO2, ONOO- and H2O2 are present in the liquid phase in similar quantities to concentrations which are reported in the literature to cause bacterial inactivation. The importance of plasma-induced chemistry at the gas-liquid interface is illustrated and discussed in detail.

van Gils, C. A. J.; Hofmann, S.; Boekema, B. K. H. L.; Brandenburg, R.; Bruggeman, P. J.

2013-05-01

231

Condensation enhancement on a pool surface caused by a submerged liquid jet  

SciTech Connect

One advanced nuclear reactor design has a residual heat removal (RHR) pipe connected to the bottom of a steam generator outlet plenum. The water in the plenum can become thermally stratified during postulated loss of coolant accidents. Cold water injected through the RHR pipe has the potential effect of increasing the steam condensation on the pool surface due to the stirring action of the jet. The amount of increase depends on a number of factors, including the jet velocity and the pool height above the jet injection point. Prediction of steam condensation rates, before and after the jet breaks the pool surface, is the topic of this paper. Data and correlations exist for pre surface breakthrough and a method has been developed for post breakthrough. The models have been incorporated into the reactor safety analysis computer software known as RELAP5. Comparisons of predictions against data are presented.

Shumway, R.W.

1997-05-01

232

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

233

Experimental study of atomization patterns produced by the oblique collision of two viscoelastic liquid jets  

Microsoft Academic Search

Experimental observations and analysis are presented for the formation and atomization of the fluid sheet created by obliquely colliding jets of viscoelastic fluids. Solutions of mono-disperse polystyrene (PS) in diethylphthalate and of poly-disperse polyethylene oxide (PEO) in glycerol\\/water mixtures were used to investigate the effects of fluid elasticity on the break-up patterns generated by the impact of two jets ejected

Sungjune Jung; Stephen D. Hoath; Graham D. Martin; Ian M. Hutchings

2011-01-01

234

Similarity between the Primary and Secondary Air-Assisted Liquid Jet Breakup Mechanisms  

Microsoft Academic Search

We report an ultrafast synchrotron x-ray phase-contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. There exist great similarities between the primary (jet) and the secondary (drop) breakup, and in the primary breakup on different length scales. A transition from a ligament- to a membrane-mediated breakup is identified around an effective Weber number We'˜13. This

Yujie Wang; Kyoung-Su Im; Kamel Fezzaa

2008-01-01

235

Effect of spanwise flexibility on aerodynamics of a plunging wing  

NASA Astrophysics Data System (ADS)

The effect of spanwise flexibility on the aerodynamic performance of a plunging wing is investigated numerically. To solve the fluid-structure interaction problem, a computational aeroelasticity framework has been developed based on an implicit coupling procedure between a pressure-based Navier-Stokes finite volume solver and a quasi-3D finite element solver capable of handling geometrically nonlinear composite beam-like and plate-like dynamic deformations. Three different variations in the spanwise flexibility of a NACA0012 cross-sectional rectangular wing of aspect ratio 3 are considered at chord Reynolds number of 3x10^4, reduced frequency (based on semi-chord) of 1.82, for prescribed pure plunge actuation at the leading edge. The computed results in terms of time histories of thrust coefficient, wing shape deformation, and flow structures are compared to experimental data. Spanwise flexibility of the plunging wing affects the amplitude and phase lag of the wing tip displacement, and hence the instantaneous angle-of-attack and associated flow structures. Together, they can substantially modify the aerodynamic force.

Aono, Hikaru; Chimakurthi, Satish Kumar; Liu, Hao; Cesnik, Carlos E. S.; Shyy, Wei

2008-11-01

236

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 1986-December 1987  

SciTech Connect

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 at about 900 BPD, is essentially a mixture of phenols, cresols, dihydric phenols, and naphthols, with an oxygen content averaging over 13 wt %. The naphtha is a low-boiling mixture extracted from syngas at about 725 BPD. Chief components are benzene, alkylbenzenes, sulfur compounds, and highly variable amounts of methanol, acetone, and methylethylketone. Based on these typical by-product characteristics, preliminary assessments were that the tar oil was the most-promising jet-fuel source, that crude phenols was a questionable source because of this high oxygen content, and that naphtha was a poor source because of its low-boiling range.

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

1988-05-01

237

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

NASA Astrophysics Data System (ADS)

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 ?m diameter jet resulting in water-window oxygen line emission at 525 eV/2.36 nm with a brightness of 3.0×109 ph/(s×?m2×sr×line). 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.; Lundström, U.; Vogt, U.; Hertz, H. M.

2010-02-01

238

Similarity between the Primary and Secondary Air-Assisted Liquid Jet Breakup Mechanisms  

NASA Astrophysics Data System (ADS)

We report an ultrafast synchrotron x-ray phase-contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. There exist great similarities between the primary (jet) and the secondary (drop) breakup, and in the primary breakup on different length scales. A transition from a ligament- to a membrane-mediated breakup is identified around an effective Weber number We'˜13. This observation reveals the critical role an effective Weber number plays in determining the atomization process and strongly supports the cascade breakup model.

Wang, Yujie; Im, Kyoung-Su; Fezzaa, Kamel

2008-04-01

239

Similarity between the primary and secondary air-assisted liquid jet breakup mechanisms.  

PubMed

We report an ultrafast synchrotron x-ray phase-contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. There exist great similarities between the primary (jet) and the secondary (drop) breakup, and in the primary breakup on different length scales. A transition from a ligament- to a membrane-mediated breakup is identified around an effective Weber number We' approximately 13. This observation reveals the critical role an effective Weber number plays in determining the atomization process and strongly supports the cascade breakup model. PMID:18518113

Wang, Yujie; Im, Kyoung-Su; Fezzaa, Kamel

2008-04-18

240

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

241

Temperature distribution in the reactive jet of water vapor and liquid sodium - contribution to wastage modelling  

Microsoft Academic Search

The possibility of water vapor leaks across the wall of one or more of the heat exchanger tubes in the steam generator constitutes one of the important problems of safety of the Fast Breeder Reactors cooled by sodium. The jet thus formed can, in fact, destroy the neighbouring tubes. The hydrodynamic, chemical and thermal factors play an important role in

F. Roger; J.-L. Carreau; L. Gbahoue; P. Hobbes; K. Y. Park

1984-01-01

242

Modelling of the atomization of a plain liquid fuel jet in crossflow at gas turbine conditions  

Microsoft Academic Search

The penetration and atomization of a plain jet of kerosene fuel in air crossflow were modelled and compared with the experiment at test conditions relevant to lean premixed prevaporized combustion in gas turbines.Tests were conducted at an air velocity of 100 and 75 m\\/s and an air pressure of 6 and 9 bar at ambient temperature. The fuel nozzle diameter

Michael Rachner; Julian Becker; Christoph Hassa; Thomas Doerr

2002-01-01

243

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

244

Low-pressure flashing mechanisms in iso-octane liquid jets  

Microsoft Academic Search

This paper examines a flashing liquid regime that takes place at very high ratios of injection to discharge pressures in flow restrictions. Typically, the flashing phenomenon has been observed in laboratory experiments where a liquid flows through a short nozzle into a low-pressure chamber at a pressure value considerably lower than the liquid saturation pressure at the injection temperature. By

M. M. Vieira; J. R. Simões-Moreira

2007-01-01

245

Unequal mass binary black hole plunges and gravitational recoil  

Microsoft Academic Search

We present results from fully nonlinear simulations of unequal mass binary black holes plunging from close separations well inside the innermost stable circular orbit with mass ratios q ? M1\\/M2 = {1, 0.85, 0.78, 0.55, 0.32}, or equivalently, with reduced mass parameters eta ? M1M2\\/(M1 + M2)2 = {0.25, 0.248, 0.246, 0.229, 0.183}. For each case, the initial binary orbital

Frank Herrmann; Ian Hinder; Deirdre Shoemaker; Pablo Laguna

2007-01-01

246

Analysis of a free surface film from a controlled liquid impinging jet over a rotating disk including conjugate effects, with and without evaporation  

Microsoft Academic Search

A detailed analysis of the liquid film characteristics and the accompanying heat transfer of a free surface controlled liquid impinging jet onto a rotating disk are presented. The computations were run on a two-dimensional axi-symmetric Eulerian mesh while the free surface was calculated with the volume of fluid method. Flow rates between 3 and 15lpm with rotational speeds between 50

Jeremy Rice; Amir Faghri; Baki Cetegen

2005-01-01

247

The theoretical simulation of the effect of solid–liquid contact angle on the critical heat flux of saturated water jet boiling on stagnation zone  

Microsoft Academic Search

A theoretical simulation was carried out for predicting the critical heat flux (CHF) of convective boiling for a round saturated water jet impingement on the stagnation zone of a hot surface. The study was focused on the effect of the solid–liquid contact angle on the CHF. A theoretical model based on the Long wave instability was applied to calculate the

Yu-hao Qiu; Zhen-hua Liu

2010-01-01

248

Flow and forces of flexible wings under a plunging motion  

NASA Astrophysics Data System (ADS)

The effects of flexibility on the flow fields and production of aerodynamic forces of Zimmerman planform wings with different stiffness are investigated. The wings are subjected to a symmetric sinusoidal plunging motion under forward flight conditions. Particle Image Velocimetry (PIV) is used to measure the flow at different spanwise locations and Laser Doppler Vibrometry (LDV) is utilized to obtain deformation characteristics from the wings. The results from the PIV and LDV analysis are phase averaged discrete points throughout the plunging cycle, resulting in three component flow field data coupled with wing twist obtained from the LDV, thus allowing for a better understanding of the fluid-structure interactions. The forces are then calculated through a momentum balance technique to better understand the effects of different stiffness. The Q criterion is used to identify and analyze the vortical structures that form around the wing. Results show the strongest leading edge vortex formation between 70 and 80 percent span. The effect of the deformation on the production and evolution of the vortical structures will be related to the generation of aerodynamic forces.

Campos, Diego; Ukeiley, Lawrence

2011-11-01

249

Atomization of Non-Newtonian Liquids by a High Momentum Coaxial Gas Jet. Stability Analysis, Modelling and Experimental Validation  

NASA Astrophysics Data System (ADS)

The atomization of a liquid jet by a co-flowing, high-speed gas has been studied for non-Newtonian polymer solutions. In this study, the R-T model originally developed by Varga et al. (2003) is extended to viscous and non-Newtonian fluids by applying the general dispersion relation developed by Joseph et al. (2002). When viscous effects are negligible the maximum amplification wavenumber is k?=?a ?l/(3?). On the contrary, when viscous effects are dominant, the wavenumber for maximum amplification can be approximated by k?=?[3]a ?l^2/?l^2. If the effects of surface tension and viscosity are assumed to be additive, the resulting R-T instability wavelength can be estimated as ?RT= 2 ?(?3 ?/ (a ?l) + C2?[3]?l^2/(a ?l^2)). The model obtained from the theoretical analysis has been validated from droplet diameter measurements of the atomization of six different liquids under a wide range of experimental conditions. The diameter and axial velocity of the liquid droplets was measured by Phase Doppler Particle Analyzer.

Aliseda, Alberto; Hopfinger, Emil; Kremer, Douglas M.; Berchielli, Alfred; Connolly, Emilia K.; Lasheras, Juan C.

2007-11-01

250

Topographic error analysis of a gear plunge shaving cutter finished by a cone grinding wheel  

Microsoft Academic Search

Gear shaving is one of the most efficient and economical ways to finish gears roughed by hobbing or shaping. The theoretical pitch surface of a gear plunge?shaving cutter is a hyperboloid with hollow tooth form. The tooth profile of a plunge shaving cutter is usually ground by a cone grinding wheel. In this paper, we propose a mathematical model to

2006-01-01

251

The Penetration Behavior of an Annular Gas-Solid Jet Impinging on a Liquid Bath: Comparison with a Conventional Circular Jet  

NASA Astrophysics Data System (ADS)

The top-blow injection technique of a gas-solid mixture through a circular lance is used in the Mitsubishi Continuous Smelting Process. One of the inherent problems associated with this injection is the severe erosion of the hearth refractory below the lances. A new configuration of the lance to form an annular gas-solid jet rather than a circular jet was designed in the laboratory scale. With this new configuration, solid particles leave the lance at a much lower velocity than the gas, and the penetration behavior of the jet is significantly different than with the circular lance in which the solid particles leave the lance at the same high velocity as the gas. The results of cold model tests using an air-sand jet issuing from a circular lance and an annular lance into a water bath showed that the penetration of the annular jet is much less sensitive to the variations in particle feed rate as well as gas velocity than that of the circular jet. Correlation equations for the penetration depth for both circular and annular jets show agreement among the experimentally obtained values.

Park, Sung Sil; Dyussekenov, Nurzhan; Sohn, H. Y.

2010-02-01

252

Research on the HYLIFE liquid-first-wall concept for future laser-fusion reactors: Liquid jet impact experiments  

Microsoft Academic Search

Transient and steady state drag of a single bar and of some selected arrays of bars were evaluated and the momentum removed from impacting liquid slugs determined. In order to achieve this aim, use was made of both the published literature and experimental data obtained from a small-scale experimental apparatus. The implications of two possible scaling laws for use in

M. A. Hoffman; A. R. Raffray

1982-01-01

253

EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Dynamics of formation of the liquid-drop phase of laser erosion jets near the surfaces of metal targets  

NASA Astrophysics Data System (ADS)

An investigation was made of laser erosion jets formed at 0.1-1.5 mm above the surfaces of Pb, Co, Ni, Sn, and Zn targets. A neodymium laser emitting rectangular pulses of 400 ?s duration and of energy up to 400 J was used. The diameters, as well as the number density and volume fraction of the metal particles present in the jet, were measured. An analysis of the results showed that the metal liquid drops broke up near the surface and experienced additional evaporation because of their motion opposite to the laser beam.

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

1995-03-01

254

Acoustic forcing to simulate the plunging motion of an airfoil  

NASA Astrophysics Data System (ADS)

An alternative to performing dynamic plunging measurements on an airfoil is presented, which is suitable for high reduced frequencies. Instead of physically displacing the airfoil, the flow is modulated by loudspeakers. The loudspeakers are tuned to the first transversal eigenfrequency of the wind tunnel, which results in a 2D acoustic field. The paper first describes the experimental investigation of the acoustic field without a main flow. Then results of acoustic field measurements are compared to a commercially available boundary-element method. The results of local pressure measurements on the airfoil are compared to predictions of a numerical solution of the Euler equations for in inviscid compressible flow. This solution includes the acoustic field. A strong point of the method is that the excitation amplitude can be varied easily.

Olsman, W. F. J.; Willems, J. F. H.; Hulshoff, S. J.; Hirschberg, A.; Trieling, R. R.

2010-08-01

255

Categorization of flow structures around a pitching and plunging airfoil  

NASA Astrophysics Data System (ADS)

Quantitative evaluation of time dependent flow structures around and in the near-wake of an oscillating airfoil is investigated using the Digital Particle Image Velocimetry (DPIV) technique to perform a detailed categorization of vortex formations in the reduced frequency range of 0.16?k?6.26 corresponding to Strouhal number range of 0.05?St?1.0. The SD7003 airfoil model known to be optimized for low Reynolds number flows undergoes a combined motion where the pitch leads the plunge motion by ?=?/2 in a steady current. Five flow structure categories are identified depending on the role of separated vortex structures from the leading and trailing edges. The occurrence of flow structure categories on different two-dimensional parameter spaces is obtained. It is also found that the categorizations are independent of the Reynolds number for the investigated range.

Fenercioglu, Idil; Cetiner, Oksan

2012-05-01

256

Dynamic behavior of reacting gas jets submerged in liquids: a photographic study. Annual report, May 1, 1985May 1, 1986  

Microsoft Academic Search

A photographic study of a hydrogen chloride gas jet reacting in an aqueous solution of ammonia was conducted. The high-speed motion pictures taken revealed that the behavior of the reacting gas jet was highly dynamic and complex. The gaseous jet penetration (''plume'') was not stationary, but underwent a change in shape and size with time, which appeared to be periodic

D. H. Cho; D. R. Armstrong; L. Bova

1986-01-01

257

Use of thermochromatic liquid crystals in the study of jet impingement cooling: sensitivity of transient heating methods  

Microsoft Academic Search

In the cooling of surfaces jet impingement arrays have been found to provide effective surface heat transfer. Considerable work has been done in identifying the optimal jet array geometry, including jet diameter, spacing and relative distance to the surface to be cooled. Most all of these studies rely on surface averaged heat transfer results. However, there are applications where the

Robin Owens; James A. Liburdy

1995-01-01

258

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

259

Experimental investigation of jet-induced mixing of a large liquid hydrogen storage tank  

Microsoft Academic Search

Experiments have been conducted to investigate the effect of fluid mixing on the depressurization of a large liquid hydrogen storage tank. The test tank is approximately ellipsoidal, having a volume of 4.89 m(exp 3) and an average wall heat flux of 4.2 W\\/m(exp 2) due to external heat input. A mixer unit was installed near the bottom of the tank

C. S. Lin; M. M. Hasan; N. T. Vandresar

1994-01-01

260

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

261

Pulsed laser-induced liquid jet for skull base tumor removal with vascular preservation through the transsphenoidal approach: a clinical investigation  

Microsoft Academic Search

Background  The transsphenoidal approach has recently been used to treat complex lesions beyond the sella turcica, but the difficulties\\u000a of dealing with small vessels, deep and narrow space, and working angle may limit the procedures. To overcome these problems,\\u000a we have developed a pulsed laser-induced liquid jet (LILJ) system to dissect tumor tissue with preservation of fine blood\\u000a vessels within deep

Yoshikazu Ogawa; Atsuhiro Nakagawa; Kazuyoshi Takayama; Teiji Tominaga

2011-01-01

262

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

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. 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.

Guffey, F.D.; Hunter, D.E.

1990-06-01

263

Turbulent flow simulation of liquid jet emanating from pressure-swirl atomizer  

NASA Astrophysics Data System (ADS)

The performances of three linear eddy viscosity models (LEVM) and one algebraic Reynolds stress model (ARSM) for the simulation of turbulent flow inside and outside pressure-swirl atomizer are evaluated by comparing the interface position with available experimental data and by comparing the turbulence intensity profiles at the atomizer exit. It is found that the turbulence models investigated exhibit zonal behaviors, i.e. none of the models investigated performs well throughout the entire flow field. The turbulence intensity has a significant influence on the global characteristics of the flow field. The turbulence models with better predictions of the turbulence intensity, such as Gatski-Speziale’s ARSM model, can yield better predictions of the global characteristics of the flow field, e.g. the reattachment lengths for the backward-facing step flow and the sudden expansion pipe flow, or the discharge coefficient, film thickness and the liquid sheet outer surface position for the atomizer flows. The standard k- ? model predicts stronger turbulence intensity as compared to the other models and therefore yields smaller film thickness and larger liquid sheet outer surface position. In average, the ARSM model gives both quantitatively and qualitatively better results as compared to the standard k- ? model and the low Reynolds number models.

Yeh, Chun-Lang

2008-01-01

264

The eye of the storm: light from the inner plunging region of black hole accretion discs  

NASA Astrophysics Data System (ADS)

It is generally thought that the light coming from the inner plunging region of black hole accretion discs contributes negligibly to the disc's overall spectrum, i.e. the plunging fluid is swallowed by the black hole before it has time to radiate. In the standard disc model used to fit X-ray observations of accretion discs, the plunging region is assumed to be perfectly dark. However, numerical simulations that include the full physics of the magnetized flow predict that a small fraction of the disc's total luminosity emanates from the plunging region. We investigate the observational consequences of this neglected inner light. We compute radiative-transfer-based disc spectra that correspond to 3D general relativistic magnetohydrodynamic simulated discs (which produce light inside their plunging regions). In the context of black hole spin estimation, we find that the neglected inner light only has a modest effect (this bias is less than typical observational systematic errors). For rapidly spinning black holes, we find that the combined emission from the plunging region produces a weak power-law tail at high energies. This indicates that infalling matter is the origin for some of the 'coronal' emission observed in the thermal dominant and steep power-law states of X-ray binaries.

Zhu, Yucong; Davis, Shane W.; Narayan, Ramesh; Kulkarni, Akshay K.; Penna, Robert F.; McClintock, Jeffrey E.

2012-08-01

265

Formation and transformation of a water bell resulting from impingement of a vertical liquid jet on a horizontal plate  

Microsoft Academic Search

The formation and transformation of a water bell resulting from the impingement of an axisymmetric water jet perpendicularly to a circular plate were investigated. The various bell shapes and their different behavior are described as a function of the diameters of the plate and nozzle, and the jet exhaust velocity. These shapes are observed when the distance between plate and

C. Goedeke

1976-01-01

266

Ignition and extinction of non-premixed flames of single-component liquid hydrocarbons, jet fuels, and their surrogates  

Microsoft Academic Search

In the present study, extinction strain rates and ignition temperatures of a wide range of jet fuels were experimentally determined in the counterflow configuration under non-premixed conditions. Similar measurements were also made for single-component hydrocarbon fuels and surrogate fuels, and were compared with those obtained for the jet fuels. The experiments were conducted at atmospheric pressure and elevated temperatures. Comparing

A. T. Holley; Y. Dong; M. G. Andac; F. N. Egolfopoulos; T. Edwards

2007-01-01

267

Distribution des températures à l'intérieur d'un jet de gaz chaud injecté dans un liquide  

Microsoft Academic Search

The distribution of temperatures in a high generating pressure impingement nitrogen jet submerged in an oil bath is determined by means of thermocouples. An analogy with homogeneous underexpanded jets is used to describe the nature of disturbances in the first portion of this flow. Further away, the radial distribution of the temperature excess can be assimilated to a Gaussian curve,

Francis Roger; Abdelaziz Benbarkat; Laurent Gbahoué; Jean-Louis Carreau

1998-01-01

268

Numerical study of a bubble plume generated by bubble entrainment from an impinging jet  

Microsoft Academic Search

The current paper presents the prediction results of a bubbly flow under plunging jet conditions using multiphase mono- and poly-dispersed approaches. The models consider interfacial momentum transfer terms arising from drag, lift, and turbulent dispersion force for the different bubble sizes. The turbulence is modeled by an extended k–? model which accounts for bubble induced turbulence. Furthermore in case of

Faiza Zidouni Kendil; Eckhard Krepper; Anis Bousbia Salah; Dirk Lucas; Amina Mataoui

2011-01-01

269

Experimental study of foam jets  

NASA Astrophysics Data System (ADS)

We investigate the flow of a foam injected through a cylindrical inlet into a quiescent liquid which is miscible with the foaming solution. Depending on a Reynolds number, combining inlet diameter, liquid viscosity, and flow rate, the jet disperses into a conical plume, takes a stable cylindrical straight shape whose radius swells with flow rate or disintegrates into blobs. We compare this behavior to that reported for other complex fluid jets and present a simple physical model for the straight jet regime.

Lespiat, Rémi; Höhler, Reinhard; Biance, Anne-Laure; Cohen-Addad, Sylvie

2010-03-01

270

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

2013-10-10

271

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

272

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

273

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

274

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

2013-05-29

275

Modeling of Flow about Pitching and Plunging Airfoil Using High-Order Schemes.  

National Technical Information Service (NTIS)

A high-order non-uniform compact finite-difference algorithm with numerical filtering and low storage Runga-Kutta scheme is developed to perform numerical simulations on orthogonal grids generated about plunging and pitching airfoils. The grids, which mov...

A. Povitsky H. Gopalan

2008-01-01

276

Updated Pumpable Liquid Volume Estimates and Jet Pump Durations for Interim Stabilization of Remaining Single Shell Tanks (SST)  

SciTech Connect

The document calculates the pumpable liquid remaining in the 11 unstabilized Consent Decree tanks, as well as updating the estimated pumpable liquid volume in the 29 Consent Decree tanks in June 1, 1998. Data is updated to April 1, 2003.

CONNER, J.M.

2003-07-01

277

Updated Pumpable Liquid Volume Estimates and Jet Pump Durations for Interim Stabilization of Remaining Single-Shell Tanks.  

National Technical Information Service (NTIS)

The document calculates the pumpable liquid remaining in the 11 unstabilized Consent Decree tanks, as well as updating the estimated pumpable liquid volume in the 29 Consent Decree tanks in June 1, 1998. Data in this document are updated to April 1, 2003.

J. M. Conner

2003-01-01

278

Modeling of wet jet in fluidized bed  

Microsoft Academic Search

A wet jet zone is established in many applications wherever feeding and dispersing a liquid, solution or slurry into fluidized bed by gases is needed. In the present study, a simple mathematical model has been developed to simulate the wet jet in fluidized bed. The different stages involved inside the jet zone have been estimated and analyzed.The evaporation stage of

F. Okasha; M. Miccio

2006-01-01

279

Needleless electrospinning: Electrically driven instability and multiple jetting from the free surface of a spherical liquid layer  

NASA Astrophysics Data System (ADS)

The following work deals with the electrically driven instability of a viscous leaky dielectric layer on a spherical surface subjected to an initially spherically symmetric electric field. It is shown that, at a certain critical voltage value, the layer becomes unstable since surface tension can no longer sustain the static equilibrium situation. As a result, radial protrusions are formed at the leaky dielectric surface, which can be beneficial in needleless electrospinning, where the formation of multiple jets originating from a single surface is desirable.

Miloh, T.; Spivak, B.; Yarin, A. L.

2009-12-01

280

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

281

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

282

The plunging-mode response of an idealized airplane to atmospheric turbulent gusts  

Microsoft Academic Search

For the plunging-mode motion of an idealized airplane with pitch neglected, the response statistics have been formulated subject to atmospheric turbulence prescribed by the so-called Dryden's energy spectrum. The stationary input-response relation yields the following conclusions. (1) Atmospheric turbulent gusts should be modeled by incorporating not only the intensity modulation but also the time-varying energy spectrum. (2) The response exceedance

J. Lee

1976-01-01

283

Effect of a Plunge Electrode During Field Stimulation of Cardiac Tissue  

NASA Astrophysics Data System (ADS)

The response of cardiac tissue to strong electric fields is determined by 3-D cable properties, bidomain anisotropy, nonlinearities, and, most importantly, heterogeneities. Langrill and Roth (IEEE Trans. BME. 48:1207 (2001)) numerically studied the effect of a plunge electrode and found alternating regions of hyperpolarization and depolarization around the electrode in response to field shock. We sought to experimentally verify their results by using field stimulation and optical imaging of di-4-ANEPPS stained rabbit right ventricles with an insulated needle serving as a plunge electrode/heterogeneity. The experimental and numerical results agree qualitatively. The key discrepancy is the larger spatial extent of the polarization in the experimental data. The combination of transmural fiber rotation and fluorescence averaging over depth may cause the spatial scale to be larger than was predicted numerically. Because adjacent regions of opposite polarization are potential sources of wave front generation, our results suggest that plunge electrodes or similar-sized heterogeneities may play a role in far-field stimulation.

Wikswo, J.; Woods, M.; Sidorov, V.; Langrill, D.; Roth, B.

2003-03-01

284

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

285

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

286

Vortex diode jet.  

National Technical Information Service (NTIS)

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 re...

E. D. Houck

1993-01-01

287

Electrowetting control of bouncing jets  

NASA Astrophysics Data System (ADS)

As recently studied, a sub-millimetric liquid jet can bounce on sufficiently hydrophobic surfaces [F.Celestini et al., Soft Matter 6(23), 5872-5876 (2010); A. Kibar et al., Exp. Fluids 49(5), 1135-1145 (2010)]. As the hydrophobicity is reduced, the reflection angle (?r) increases and the jet rebound deviates more and more from specular reflection. In the present study, we vary the wetting properties of the substrate using the electrowetting effect to induce a change in the reflection angle. A liquid jet is sent toward a metallic surface coated by an insulating, hydrophobic layer. Applying an ac voltage between the metallic nozzle and the electrode below the insulating layer, we can precisely control the reflection angle of the jet. The effects of the amplitude and the frequency of the applied voltage are analyzed. This study can find applications for the control of jet dynamics.

Noblin, Xavier; Celestini, Franck

2012-08-01

288

Combustion of liquid fuel in the counter-swirled jets of a gas turbine plant annular combustion chamber  

Microsoft Academic Search

Tests were carried out on an annular combustion chamber rig with a stabilizer of the type used in the GTN-25 gas turbine plant to determine the feasibility of burning a liquid fuel (diesel fuel, GOST 4749-73) in a combustion chamber of this type. Very high performance was obtained for a number of important characteristics of the microflame combustion process in

A. G. Tumanovskii; N. N. Semichastnyi; K. Iu. Sokolov

1986-01-01

289

Research on the HYLIFE liquid-first-wall concept for future laser-fusion reactors: liquid jet impact experiments. Final report No. 8  

Microsoft Academic Search

The goal of this initial scoping study was to evaluate the transient and steady state drag of a single bar and of some selected arrays of bars and to determine the momentum removed from impacting liquid slugs. In order to achieve this aim, use has been made of both the published literature and experimental data obtained from a small-scale experimental

Hoffman

1982-01-01

290

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

291

Étude de l'établissement d'un jet liquide laminaire émergeant d'une conduite cylindrique verticale semi-infinie et soumis à l'influence de la gravité  

Microsoft Academic Search

On étudie l'écoulement libre d'un jet liquide laminaire axisymétrique émergeant d'une conduite cylindrique verticale semi-infinie, à grands nombres de Reynolds et grands nombres de Froude. Dans de telles conditions, si l'on exclut le cas des tubes capillaires, le nombre de Weber de l'écoulement est suffisamment grand pour que les effets de tension superficielle s'avèrent négligeables, ainsi que le confirme cette

C. Philippe; P. Dumargue

1991-01-01

292

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.

293

Optimization of laser parameters for the maximum efficiency in the generation of water-window radiation using a liquid nitrogen jet  

SciTech Connect

A laser-produced plasma is a suitable compact x-ray source that can be of broad band or quasimonochromatic with a proper choice of material and filter. To address the maximum conversion efficiency for an efficient, quasimonochromatic source at 2.88 nm (N VI 1s{sup 2}-1s2p transition) using liquid nitrogen jet for soft x-ray microscopy, the radiation characteristics such as absolute intensity, spectra, and angular distribution have been investigated for different laser pulse durations (picosecond and femtosecond pulses) and laser energies The comparison of conversion efficiencies between picosecond [120 ps full width at half maximum (FWHM)] and femtosecond (40-500 fs FWHM) lasers indicates that the picosecond laser would provide better conversion efficiency, which is 1.6% at 2x10{sup 13} W/cm{sup 2}. The investigation shows that the laser intensity for the maximum conversion efficiency scales as I{sub m}{proportional_to}1/{tau}{sup {alpha}}, where {alpha}=0.9{+-}0.15. This empirical formula is useful to choose the laser parameters properly for a given pulse width.

Kim, B.; Ahn, B.; Lee, D.; Kim, J.; Kim, D. [Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Vacuum and Measurement Technology, Pohang 790-320 (Korea, Republic of); Department of Physics, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of)

2006-04-03

294

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

295

Astrophysical Jets  

ScienceCinema

Many astrophysical sources - especially those powered by release of gravitational energy - are associated with an outflow of material, generally taking place along the axis of symmetry of the system. In the most extreme cases, the outflow is accelerated to relativistic speeds; such a phenomenon is known as an astrophysical jet. When a relativistic jet points close to our line of sight, the observed radiation is strongly Doppler-boosted. Most spectacular cases of astrophysical jets are those produced by active galactic nuclei, where the measured spectrum - presumably dominated by the radiation from the jet - reaches up to the multi-GeV range. Our knowledge of these jets is limited: we don't fully understand how are they formed, collimated, and accelerated, and what is the process of conversion of the bulk energy of the jet into radiation. We anticipate that the increased sensitivity of GLAST will provide us with spectacular data yielding new insights as to their origin and structure.

296

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

297

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

298

Research on the HYLIFE liquid-first-wall concept for future laser-fusion reactors: liquid jet impact experiments. Final report No. 8  

SciTech Connect

The goal of this initial scoping study was to evaluate the transient and steady state drag of a single bar and of some selected arrays of bars and to determine the momentum removed from impacting liquid slugs. In order to achieve this aim, use has been made of both the published literature and experimental data obtained from a small-scale experimental apparatus. The implications of two possible scaling laws for use in designing the small-scale experiment are discussed. The use of near-universal curves to evaluate the momentum removed during the initial transient period is described. The small-scale apparatus used to obtain steady-state drag data is described. Finally, these results are applied to the HYLIFE fusion reactor.

Hoffman, M.A.

1982-08-01

299

Transition from inspiral to plunge in precessing binaries of spinning black holes  

SciTech Connect

We investigate the nonadiabatic dynamics of spinning black-hole binaries by using an analytical Hamiltonian completed with a radiation-reaction force, containing spin couplings, which matches the known rates of energy and angular-momentum losses on quasicircular orbits. We consider both a straightforward post-Newtonian-expanded Hamiltonian (including spin-dependent terms), and a version of the resummed post-Newtonian Hamiltonian defined by the effective one-body approach. We focus on the influence spin terms have on the dynamics and waveforms. We evaluate the energy and angular momentum released during the final stage of inspiral and plunge. For an equal-mass binary the energy released between 40 Hz and the frequency beyond which our analytical treatment becomes unreliable is found to be, when using the effective one-body dynamics, 0.6%M for antialigned maximally spinning black holes, 5%M for aligned maximally spinning black holes, and 1.8%M for nonspinning configurations. In confirmation of previous results, we find that, for all binaries considered, the dimensionless rotation parameter J/E{sup 2} is always smaller than unity at the end of the inspiral, so that a Kerr black hole can form right after the inspiral phase. By matching a quasinormal mode ring down to the last reliable stages of the plunge, we construct complete waveforms approximately describing the gravitational-wave signal emitted by the entire process of coalescence of precessing binaries of spinning black holes.

Buonanno, Alessandra; Chen, Yanbei; Damour, Thibault [AstroParticule et Cosmologie (APC), 11 place Marcelin Berthelot, 75005 Paris (France); Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Am Muehlenberg 1, D-14476 Golm bei Potsdam (Germany); Institut des Hautes Etudes Scientifiques, 91440 Bures-sur-Yvette (France)

2006-11-15

300

Sublingual-plunging ranula as a complication of supraomohyoid neck dissection.  

PubMed

Ranulas are rare cystic lesions resulting from damage or rupture of one or more of the ducts of the sublingual gland, that lead to mucus extravasation or dilatation of the gland's duct. Extravasation cysts are more common than retention cysts. We present a case of a 45-year-old male with a squamous cell carcinoma of the ventral surface of the tongue that was treated with excision of the oral lesion and bilateral supraomohyoid neck dissection without supplementary radiotherapy. A left myocutaneous platysma flap was raised for defect closure. Ten months postoperatively he presented complaining of swelling of the right submandibular region. The diagnosis, based on his medical anamnesis and the CT imaging, was a sublingual-plunging ranula. It is postulated that the ranula resulted from damage to the ducts of the sublingual gland during selective neck dissection. One year postoperatively there are no signs of recurrence either of the ranula or of the cancer. We suggest that sublingual gland excision and intraoral cyst marsupialization is a logical treatment for sublingual-plunging ranulas. PMID:22096692

Dietrich, Eva-Maria; Vasilios, Banikas; Maria, Lazaridou; Styliani, Papaemmanouil; Konstantinos, Antoniades

2011-03-03

301

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

302

Air entrainment upon liquid impact  

NASA Astrophysics Data System (ADS)

The impact of round and plane liquid jets on plane liquid surfaces is simulated numerically on the basis of a potential flow model. It is found that the mass of the jet is as important as its momentum in determining the flow. For sufficiently long jets and small Froude numbers air cavities are entrained. Entrainment is more unlikely in two dimensions than in three.

Prosperetti, A.; Oguz, H. N.

303

Transition from adiabatic inspiral to geodesic plunge for a compact object around a massive Kerr black hole: Generic orbits  

SciTech Connect

The inspiral of a stellar mass compact object falling into a massive Kerr black hole can be broken into three different regimes: An adiabatic inspiral phase, where the inspiral time scale is much larger than the orbital period; a late-time radial infall, which can be approximated as a plunging geodesic; and a regime where the body transitions from the inspiral to plunge. In earlier work, Ori and Thorne have outlined a method to compute the trajectory during this transition for a compact object in a circular, equatorial orbit. We generalize this technique to include inclination and eccentricity.

Sundararajan, Pranesh A. [Department of Physics and MIT Kavli Institute, MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

2008-06-15

304

Synthetic jets  

Microsoft Academic Search

The evolution of a synthetic (zero-net mass flux) jet and the flow mechanisms of its interaction with a cross flow are reviewed. An isolated synthetic jet is produced by the interactions of a train of vortices that are typically formed by alternating momentary ejection and suction of fluid across an orifice such that the net mass flux is zero. A

Ari Glezer; Michael Amitay

2002-01-01

305

Behavior of conducting solid or liquid jet moving in magnetic field: (1) paraxial; (2) transverse; (3) oblique  

SciTech Connect

When a conductor moves through a nonuniform magnetic field, eddy currents flow that interact with the field to decelerate the conductor and perhaps change its trajectory, orientation and, if a liquid, shape. A rod of radius a = 1 cm and the density and electrical conductivity of melted gallium ({gamma} = 6.1 g/cm{sup 3}, {rho} = 26 {micro}{Omega} cm) will decelerate 6.3 m/s in a 0.5 m ramp of paraxial field with a constant gradient g of 40 T/m ({Delta}B = 20 T). The deceleration is proportional to a{sup 2}g{Delta}B/{gamma}{rho}, independent of the velocity. The bar decelerates about twice as much in a 20 T, 0.5 m ramp of transverse field. A bar traveling at a shallow angle to such a field decelerates about 6.3 m/s. If the bar is 0.25 m long and moves at 20 m/s, it aligns with the field in {approximately}10 ms, during which time it advances {approximately}0.2 m.

Weggel, R.J.

1998-06-01

306

Vortex diode jet  

SciTech Connect

A fluid transfer system is described 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. 10 figures.

Houck, E.D.

1994-05-17

307

Jet impact on a soap film  

NASA Astrophysics Data System (ADS)

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.

Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

2012-09-01

308

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

2012-09-04

309

Measurement of physical characteristics of bubbles in gas-liquid plumes: Part II. Local properties of turbulent air-water plumes in vertically injected jets  

NASA Astrophysics Data System (ADS)

The structural development of air-water bubble plumes during upward injection into a ladle-shaped vessel has been measured under different conditions of air flow rate, orifice diameter, and bath depth. The measured radial profiles of gas fraction at different axial positions in the plume were found to exhibit good similarity, and the distribution of the phases in the plume was correlated to the modified Froude number. Different regions of flow behavior in the plume were identified by changes in bubble frequency, bubble velocity, and bubble pierced length which occur as bubbles rise in the plume. Measurement of bubble velocity indicates that close to the nozzle the motion of the gas phase is strongly affected by the injection velocity; at injection velocities below 41 m/s, the velocity of the bubbles along the centerline exhibits an increase with height, while above, the tendency reverses. High-speed film observations suggest that this effect is related to the nature of gas discharge, i.e., whether the gas discharge produces single bubbles or short jets. In this region of developing flow, measurement of bubble frequency and pierced length indicates that break-up of the discharging bubbles occurs until a nearly constant bubble-size distribution is established in a region of fully developed flow. In this largest zone of the plume the bubbles influence the flow only through buoyancy, and the spectra of bubble pierced length and diameter can be fitted to a log-normal distribution. Close to the bath surface, a third zone of bubble motion behavior is characterized by a faster decrease in bubble velocity as liquid flows radially outward from the plume.

Castillejos, A. H.; Brimacombe, J. K.

1987-12-01

310

A further proof of polarization vision of Notonecta glauca and a note on threshold intensity for eliciting the plunge reaction  

Microsoft Academic Search

Summary Polarized UV light from a platform on the ground can attract backswimmers and elicit plunge reactions. Threshold intensity is independent of the overall UV-intensity in the surrounding space. Unpolarized UV light attracts the animals only when the intensity is higher than that of the surroundings. These results show that polarized UV light can be discriminated from unpolarized UV light

R. Schwind

1985-01-01

311

Methane Sampling Technique and the Measurement of Plunge Pool Impact on Gas Transfer Rates at Low-Head Hydraulic Structures.  

National Technical Information Service (NTIS)

In situ dissolved methane gas was used as a tracer for estimating the gas transfer rates of flow over low-head hydraulic structures. The methane measurement provided a means to assess the effects of the plunging flow in the structure stilling basin. Simul...

D. E. Hibbs J. S. Gulliver J. P. McDonald

1995-01-01

312

Visual accommodation and active pursuit of prey underwater in a plunge-diving bird: the Australasian gannet  

PubMed Central

Australasian gannets (Morus serrator), like many other seabird species, locate pelagic prey from the air and perform rapid plunge dives for their capture. Prey are captured underwater either in the momentum (M) phase of the dive while descending through the water column, or the wing flapping (WF) phase while moving, using the wings for propulsion. Detection of prey from the air is clearly visually guided, but it remains unknown whether plunge diving birds also use vision in the underwater phase of the dive. Here we address the question of whether gannets are capable of visually accommodating in the transition from aerial to aquatic vision, and analyse underwater video footage for evidence that gannets use vision in the aquatic phases of hunting. Photokeratometry and infrared video photorefraction revealed that, immediately upon submergence of the head, gannet eyes accommodate and overcome the loss of greater than 45 D (dioptres) of corneal refractive power which occurs in the transition between air and water. Analyses of underwater video showed the highest prey capture rates during WF phase when gannets actively pursue individual fish, a behaviour that very likely involves visual guidance, following the transition after the plunge dive's M phase. This is to our knowledge the first demonstration of the capacity for visual accommodation underwater in a plunge diving bird while capturing submerged prey detected from the air.

Machovsky-Capuska, Gabriel E.; Howland, Howard C.; Raubenheimer, David; Vaughn-Hirshorn, Robin; Wursig, Bernd; Hauber, Mark E.; Katzir, Gadi

2012-01-01

313

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

314

Gas entrainment in an evaporating spray jet  

Microsoft Academic Search

Gas entrainment induced by a spray jet can be significantly affected by the spray evaporation rate. In this study, we have directly measured the air entrainment induced by a liquid nitrogen spray jet into an unbounded and stagnant room air. It is realized that the air entrainment is proportional to the axial gradient of oxygen mass flow in a pure

Muhammad Mushahid Rafique Qureshi; Chao Zhu

2006-01-01

315

CIRCULATION IN LARGE SCALE JET BUBBLE COLUMNS  

Microsoft Academic Search

A hydrodynamic study in a gas-liquid jet bubble column was undertaken in a column with a 122 cm diameter cylindrical section and a conical bottom section approximately 180cm in height. Due to the jetting action in the cone, the circulation patterns are different from those in cylindrical bubble columns. In order to examine this difference in flow pattern, circulation velocity

Y. T. SHAH; N. YANG; S. D. GHARAT; K. WISECARVER; B. SOLARI

1991-01-01

316

Twin Jet.  

National Technical Information Service (NTIS)

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 clos...

B. Henderson R. Bozak

2010-01-01

317

Steam reforming of liquid hydrocarbon fuels for micro-fuel cells. Pre-reforming of model jet fuels over supported metal catalysts  

Microsoft Academic Search

The present work deals with pre-reforming of logistic hydrocarbon fuel (jet fuel) as a part of an integrated approach to developing an on-board fuel reformer for use in a micro-solid-oxide fuel cell system. The purpose of doing pre-reforming is to ensure carbon-free reformulation of JP-8 jet fuel into hydrogen and carbon monoxide for use in a micro-solid-oxide fuel cell. Several

Jian Zheng; James Jon Strohm; Chunshan Song

2008-01-01

318

Oscillatory Flow of a Jet into a Blind Cavity  

Microsoft Academic Search

OBSERVATION of the flow pattern of a two-dimensional liquid jet directed into a blind cavity formed by solid surfaces indicates that the entire pattern may be treated as a fluidic oscillator circuit. The cavity was in a two-dimensional format, with an end wall transverse to the jet flow and side walls parallel to the jet extending back past the nozzle.

N. A. Molloy; P. L. Taylor

1969-01-01

319

A MODEL FOR THE REMOVAL OF WATER DROPLET AEROSOLS FROM A FLASHING JET IMPINGING ONTO A PLATE  

Microsoft Academic Search

In this paper, we present an approach to modelling the removal of water aerosol droplets from a flashing jet that is impinging onto a flat surface. The entire process, from the break to the impingement surface, is dealt with in several sequential regions: flashing, jet expansion, jet deflection and jet impingement. In the flashing region, the single-phase liquid jet is

Hsu-Wen Chiang

2000-01-01

320

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

321

The flow structure in the near field of jets and its effect on cavitation inception, and, Implementation of ferroelectric liquid crystal and birefringent crystal for image shifting in particle image velocimetry  

NASA Astrophysics Data System (ADS)

Cavitation experiments performed in the near field of a 50-mm diameter (D) jet at ReD = 5 × 105, showed inception in the form of inclined ``cylindrical'' bubbles at axial distances (x/D) less than 0.55, with indices of 2.5. On tripping the boundary layer, cavitation inception occurred at x/D ~ 2, as distorted ``spherical'' bubbles with inception indices of 1.7. To investigate these substantial differences, the near field of the jet was measured using Particle Image Velocimetry (PIV). Data on the primary flow, the strength distribution of the ``streamwise''vortices and the velocity profiles within the initial boundary layers were obtained. The untripped case showed a direct transition to three-dimensional flow in the near field (x/D < 0.7) even before rolling up to distinct vortex rings. Strong ``streamwise'' vortices with strengths up to 25% of the jet velocity times the characteristic wavelength were seen. Cavitation inception occurred in the core of these vortices. In contrast, in the tripped jet the vortex sheet rolled up to the familiar Kelvin- Helmholtz vortex rings with weak secondary vortices. Using the measured nuclei distribution, strengths and straining of the ``streamwise'' structures, the rates of cavitation events were estimated. The estimated results match very well with the measured cavitation rates. Also, the Reynolds stresses in the near field of the jet show similar trends and magnitudes to those of Browand & Latigo (1979) and Bell & Mehta (1990) for a plane shear layer. In the second part of this essay we discuss the implementation of electro-optical image shifting to resolve directional ambiguity in PIV measurements. The technique uses a ferroelectric liquid crystal (FLC) as an electro-optic half wave plate and a birefringent crystal (calcite) as the shifter. The system can be used with non-polarized light sources and fluorescent particles. The minimum shifting time is approximately 100?s. This compact electrooptical device usually is positioned in front of the camera lens, though it has also been mounted inside the lens body. This device extensively was used to acquire data in the near field of the jet, which is discussed in Chapter 2. Sample vector maps from a turbulent multidirectional flow are also included.

Gopalan, Shridhar

1999-10-01

322

Axial Jet Mixing of Ethanol in Spherical Containers During Weightlessness.  

National Technical Information Service (NTIS)

An experimental program was conducted to examine the liquid flow patterns that result from the axial jet mixing of ethanol in 10-centimeter-diameter spherical containers in weightlessness. Complete liquid circulation flow patterns were easily established ...

J. C. Audelott

1976-01-01

323

The Penetration Behavior of an Annular Gas-Solid Jet Impinging on a Liquid Bath: The Effects of the Density and Size of Solid Particles  

NASA Astrophysics Data System (ADS)

Top-blow injection of a gas-solid jet through a circular lance is used in the Mitsubishi Continuous Smelting Process. One problem associated with this injection is the severe erosion of the hearth refractory below the lances. A new configuration of the lance to form an annular gas-solid jet rather than the circular jet was designed in this laboratory. With this new configuration, the solid particles fed through the center tube leave the lance at a much lower velocity than the gas, and the penetration behavior of the jet is significantly different from that with a circular lance where the solid particles leave the lance at the same high velocity as the gas. In previous cold-model investigations in this laboratory, the effects of the gas velocity, particle feed rate, lance height of the annular lance, and the cross-sectional area of the gas jet were studied and compared with the circular lance. This study examined the effect of the density and size of the solid particles on the penetration behavior of the annular gas-solid jet, which yielded some unexpected results. The variation in the penetration depth with the density of the solid particles at the same mass feed rate was opposite for the circular lance and the annular lance. In the case of the circular lance, the penetration depth became shallower as the density of the solid particles increased; on the contrary, for the annular lance, the penetration depth became deeper with the increasing density of particles. However, at the same volumetric feed rate of the particles, the density effect was small for the circular lance, but for the annular lance, the jets with higher density particles penetrated more deeply. The variation in the penetration depth with the particle diameter was also different for the circular and the annular lances. With the circular lance, the penetration depth became deeper as the particle size decreased for all the feed rates, but with the annular lance, the effect of the particle size was small. The overall results including the previous work indicated that the penetration behavior of an annular jet is much less sensitive to the variations in operating variables than that of a circular jet. Correlation equations for the penetration depth that show good agreements with the measured values have been developed.

Chang, J. S.; Sohn, H. Y.

2012-08-01

324

Laser-induced break-up of water jet waveguide  

Microsoft Academic Search

In this article, an optical method to control the break-up of high-speed liquid jets is proposed. The method consists of focusing the light of a pulsed laser source into the jet behaving as a waveguide. Experiments were performed with the help of a Q-switched frequency doubled Nd:Yag laser ( ?=532 nm). The jet diameter was 48 µm and jet velocities from 100

P. Couty; Á. Spiegel; N. Vágó; B. I. Ugurtas; P. Hoffmann

2004-01-01

325

Air Entrainment by an Inclined Jet  

NASA Astrophysics Data System (ADS)

A smooth inclined jet impinging on an otherwise undisturbed liquid surface does not entrain air even at Reynolds numbers as large as 10,000 or more. Air entrainment requires that the jet surface be subject to sufficiently large disturbances. In order to study the phenomenon experimentally an isolated disturbance is generated on a smooth inclined jet by rapidly increasing the flow rate. The bulge that forms in this way is convected by the jet and impacts the liquid surface forming a cavity. When this cavity closes, air is entrained and splashing is observed. An overview of the different dynamic phenomena leading to these processes is presented. Quantitative data on the dependence of the entrained air volume on the jet flow rate and inclination angle are given.

Ohl, Claus-Dieter; Oguz, Hasan; Prosperetti, Andrea

1999-11-01

326

Eccentric binary black-hole mergers: The transition from inspiral to plunge in general relativity  

SciTech Connect

We study the transition from inspiral to plunge in general relativity by computing gravitational waveforms of nonspinning, equal-mass black-hole binaries. We consider three sequences of simulations, starting with a quasicircular inspiral completing 1.5, 2.3 and 9.6 orbits, respectively, prior to coalescence of the holes. For each sequence, the binding energy of the system is kept constant and the orbital angular momentum is progressively reduced, producing orbits of increasing eccentricity and eventually a head-on collision. We analyze in detail the radiation of energy and angular momentum in gravitational waves, the contribution of different multipolar components and the final spin of the remnant, comparing numerical predictions with the post-Newtonian approximation and with extrapolations of point-particle results. We find that the motion transitions from inspiral to plunge when the orbital angular momentum L=L{sub crit}{approx_equal}0.8M{sup 2}. For L

Sperhake, Ulrich; Bruegmann, Bernd [Theoretisch Physikalisches Institut, Friedrich Schiller Universitaet, 07743 Jena (Germany); Berti, Emanuele [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); McDonnell Center for the Space Sciences, Department of Physics, Washington University, St. Louis, MR 63130 (United States); Cardoso, Vitor [Department of Physics and Astronomy, The University of Mississippi, University, Mississippi 38677-1848 (United States); Centro Multidisciplinar de Astrofisica-CENTRA, Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Gonzalez, Jose A. [Theoretisch Physikalisches Institut, Friedrich Schiller Universitaet, 07743 Jena (Germany); Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Edificio C-3, Ciudad Universitaria C. P. 58040 Morelia, Michoacan (Mexico); Ansorg, Marcus [Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, 14476 Golm (Germany)

2008-09-15

327

Investigation of compound jet electrospray: Particle encapsulation  

NASA Astrophysics Data System (ADS)

Experiments were performed to investigate the effect of surface tension on the particle encapsulation formation in the compound jet electrospray process. The outer liquid used in this study were olive oil and mineral oil; and inner liquids were ethanol, tri-butyl phosphate, ethylene glycol, and triethylene glycol. It was found that the core-shell structured droplets are formed only when the ratio of charge relaxation lengths of the inner and outer jets [i.e., rO*/rI*, where r*=(Q?V0/K)1/3, in which Q is the liquid feed flow rate, K is electrical conductivity, and V is the dielectric constant of liquid] is less than 500, and the ratio of inertial breakup lengths of the inner and outer jets [i.e., RO*/RI*, where R*=(?Q2/?)1/3, in which ? and ? are the density and surface tension of liquid, respectively] is less than 0.015. In this work we further studied the effect of inner and outer liquid flow rates on the size of compound droplets using an Aerosizer (TSI model 3220). The parameters affecting the droplet size distribution were obtained. We also observed that the spray current emitted through the compound jet was merely a linear function of the inner jet flow rate. This observation implies that olive oil and mineral oil, as the outer liquids, serve as an electrically insulated layer during the spray process.

Mei, Fan; Chen, Da-Ren

2007-10-01

328

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

329

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

330

Absolute instability of a viscous hollow jet.  

PubMed

An investigation of the spatiotemporal stability of hollow jets in unbounded coflowing liquids, using a general dispersion relation previously derived, shows them to be absolutely unstable for all physical values of the Reynolds and Weber numbers. The roots of the symmetry breakdown with respect to the liquid jet case, and the validity of asymptotic models are here studied in detail. Asymptotic analyses for low and high Reynolds numbers are provided, showing that old and well-established limiting dispersion relations [J. W. S. Rayleigh, The Theory of Sound (Dover, New York, 1945); S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability (Dover, New York, 1961)] should be used with caution. In the creeping flow limit, the analysis shows that, if the hollow jet is filled with any finite density and viscosity fluid, a steady jet could be made arbitrarily small (compatible with the continuum hypothesis) if the coflowing liquid moves faster than a critical velocity. PMID:17358457

Gañán-Calvo, Alfonso M

2007-02-06

331

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

332

Production of jet fuel from coal-derived liquids. Report No. 16: Quarterly technical progress report, second quarter FY 1988, January 1, 1988-March 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 D. J. Soderberg

1990-01-01

333

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

334

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

335

Impinging axisymmetric jet  

Microsoft Academic Search

The characteristics of an axisymmetric air jet with a fully developed pipe flow exit condition impinging vertically onto a flat plate was studied experimentally using hot wire anemometry and flow visualization. The jet to plate spacings ranged from one to five jet diameters and Reynold numbers (based on jet centerline velocity and jet diameter) varied from 40 to 23000. A

Savas Aydore

1991-01-01

336

Axial jet mixing of ethanol in spherical containers during weightlessness  

Microsoft Academic Search

An experimental program was conducted to examine the liquid flow patterns that result from the axial jet mixing of ethanol in 10-centimeter-diameter spherical containers in weightlessness. Complete liquid circulation flow patterns were easily established in containers that were less than half full of liquid, while for higher liquid fill conditions, vapor was drawn into the inlet of the simulated mixer

J. C. Audelott

1976-01-01

337

Meson Production Simulations for a Mercury Jet Target  

SciTech Connect

A study of target parameters for a high-power, liquid mercury jet target system for a neutrino factory or muon collider is presented. Using the MARS15 code, we simulate particle production initiated by incoming protons below the jet with kinetic energies between 2 and 100 GeV. For each proton beam energy, we maximize production by varying the geometric parameters of the target: the mercury jet radius, the incoming proton beam angle, and the crossing angle between the mercury jet and the proton beam. With an 8 GeV proton beam, we study the variation of meson production with the direction of the proton beam relative to the jet.

Ding, X.; Cline, D. [Department of Physics and Astronomy, University of California at Los Angeles, Los Angeles, California 90095 (United States); Kirk, H.; Berg, J. S. [Brookhaven National Laboratory, Upton, New York 11973 (United States)

2010-03-30

338

Liquid atomization in supersonic flows  

Microsoft Academic Search

An experimental investigation of the atomization of a round liquid jet by coaxial, costream injection into a supersonic, Mach 1.5 air flow is reported. Extensive flow visualization was conducted using schlieren\\/shadowgraph, flash photography, and short duration (ns) laser imaging. The finer details of the jet were revealed when viewed under high magnification with the help of a microscope. The liquid

Azzedine Missoum

1993-01-01

339

Electrohydrodynamic (EHD) stimulation of jet breakup  

NASA Astrophysics Data System (ADS)

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.

1982-03-01

340

Mass transfer in round turbulent water jets  

SciTech Connect

Based upon the results of earlier theoretical and experimental work, a technique was developed to measure liquid side mass transfer coefficients for round turbulent water jets of varying velocity, diameter and length. The results obtained with this technique exhibited considerable scatter which was demonstrated to be due to severe limitations of the experimental technique. A companion analytical study showed that, contrary to the fully developed assumption of previous investigators, mass transfer in turbulent jets is an entrance region problem, and indicated that a radical change in the experiment design was required to obtain useful information regarding the liquid side mass transfer coefficient. In addition, the analytical study suggests that, within the parameter range of interest, the mass transfer coefficient for a turbulent jet may be taken to be the same as for a laminar jet since the developing concentration boundary layer never penetrates deeply into the region where turbulent transport is significant.

Leininger, T.F.

1983-02-01

341

Liquid sampling system  

Microsoft Academic Search

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

L. L. Larson

1984-01-01

342

Liquid sampling system  

Microsoft Academic Search

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

Loren L

1987-01-01

343

Atomization of a High Speed Jet  

NASA Astrophysics Data System (ADS)

We present a numerical study of the jet breakup and spray formation in a diesel engine by the Front Tracking method. The mechanisms of jet breakup and spray formation of a high speed diesel jet injected through a circular nozzle are the key to design a fuel efficient, nonpolluting diesel engine. Many parameters such as the nuzzle shape, the velocity and the turbulence of the jet and the thermodynamic states of liquid and gas could be contributing causes for jet breakup. We conduct the simulations for the jet breakup within a 2D axis-symmetric geometry. Our goal is to model the spray at a micro-physical level, with the creation of individual droplets. The problem is multiscale. The droplets are a few microns in size. The nozzle is about 0.2 mm in diameter and 1 mm in length. In order to resolve various physical patterns such as vortex, shock waves, vacuum and track droplets and spray, the Burger-Colella adaptive mesh refinement technique is used. We model mixed vapor-liquid region through a heterogeneous model with dynamic vapor bubble insertion. On the liquid/vapor interface, a phase transition problem is solved numerically.

Xu, Zhiliang; Samulyak, Roman; Li, Xiaolin; Tzanos, Constantine

2005-11-01

344

Liquid atomization in supersonic flows  

NASA Astrophysics Data System (ADS)

An experimental investigation of the atomization of a round liquid jet by coaxial, costream injection into a supersonic, Mach 1.5 air flow is reported. Extensive flow visualization was conducted using schlieren/shadowgraph, flash photography, and short duration (ns) laser imaging. The finer details of the jet were revealed when viewed under high magnification with the help of a microscope. The liquid and air pressures were varied individually. Photographic evidence indicates the presence of three regions within the liquid jet: a primary region enclosed by the first shock cell where the primary breakup occurs, a secondary region in which the jet is totally broken because of its interaction with the supersonic wave structure, and a third, subsonic region further downstream. It was found that the breakup mechanism of liquid jets in supersonic airstreams is quite complex. The breakup seems to be initiated by the growth of the turbulent structure on the liquid surface and the subsequent detachment of the three-dimensional structure as fine droplets by the intense shear at the liquid-gas interface. This seems to confirm the boundary layer stripping mechanism. The liquid jet expands into a bubble like formation as it interacts with the first set of waves. Higher liquid injection pressures resulted in higher initial spray angles. The liquid jet displayed a geometry strongly dependent on the pressure distribution resulting from the wave structure present in the supersonic jet. Droplet size and velocity distributions were measured by the P/DPA (Phase/Doppler Particle Analyzer) system. The Sauter Mean Diameter (SMD) was measured at several axial and radial locations at various liquid and air pressures. The SMD shows a decrease with increase in both the air-to-liquid mass flow ratio and the Weber number. The drop size decreased towards the outer edges of the jet. The results lead one to conclude that the coaxial, coflowing configuration is very attractive for atomizing scramjet liquid fuels.

Missoum, Azzedine

345

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

346

Analysis of maximum pressure attainable by water jet impact  

SciTech Connect

The maximum pressure attainable in an impacting jet has been addressed by researchers for jet-cutting technology, notably in rock-drilling operations and the minimization of turbine-blade erosion. The authors have analyzed the maximum pressure attainable in a liquid jet when it impinges on a rigid surface. The CALE hydrodynamics code has been used for this purpose. The calculated maximum pressure for a given jet velocity is higher than the so-called water-hammer value, {rho}{sub 0}C{sub 0}V where the term {rho} denotes the liquid density, C the sound speed, V the flow velocity, and the subscript o the undisturbed (upstream) region in the jet. However, the calculated results agree well with experimental data and with a well-known generalized water hammer pressure expression for high (as well as low) jet velocities.

Reitter, T.A.; Kang, S.W.

1993-05-01

347

Analysis of maximum pressure attainable by water jet impact  

SciTech Connect

The maximum pressure attainable in an impacting jet has been addressed by researchers for jet-cutting technology, notably in rock-drilling operations and the minimization of turbine-blade erosion. The authors have analyzed the maximum pressure attainable in a liquid jet when it impinges on a rigid surface. The CALE hydrodynamics code has been used for this purpose. The calculated maximum pressure for a given jet velocity is higher than the so-called water-hammer value, [rho][sub 0]C[sub 0]V where the term [rho] denotes the liquid density, C the sound speed, V the flow velocity, and the subscript o the undisturbed (upstream) region in the jet. However, the calculated results agree well with experimental data and with a well-known generalized water hammer pressure expression for high (as well as low) jet velocities.

Reitter, T.A.; Kang, S.W.

1993-05-01

348

Focusing capillary jets close to the continuum limit  

NASA Astrophysics Data System (ADS)

The demand for techniques that can reliably deliver and control nanometre-scale volumes of liquid is a growing priority in biotechnology and medicine. Capillary jets are capable of supplying a steady stream of monodisperse liquid droplets. But because of the increasing forces and pressures needed to counteract surface tension for droplets of decreasing size, reaching the nanoscale with such an approach is difficult. One way of overcoming such limitations is to electrostatically focus a jet as it emerges from a capillary. Another, which we report here, is to focus such a jet by hydrodynamic means, a double flow-focusing arrangement that involves a manifold capillary that delivers a second immiscible fluid jet that envelopes and guides the jet from an inner capillary. Under the appropriate working conditions, this enables the generation of continuous steady capillary fluid jets down to submicrometre diameter-approaching the ultimate continuum limit, which is supported by a proposed theory.

Gañán-Calvo, Alfonso M.; González-Prieto, Román; Riesco-Chueca, Pascual; Herrada, Miguel A.; Flores-Mosquera, María

2007-10-01

349

Electrically Driven Jets  

Microsoft Academic Search

Fine jets of slightly conducting viscous fluids and thicker jets or drops of less viscous ones can be drawn from conducting tubes by electric forces. As the potential of the tube relative to a neighbouring plate rises, viscous fluids become nearly conical and fine jets come from the vertices. The potentials at which these jets or drops first appear was

Geoffrey Taylor

1969-01-01

350

Modeling of tangential synthetic jet actuators used for pitching control on an airfoil  

NASA Astrophysics Data System (ADS)

Pitching moment control in an airfoil can be achieved by trapping concentrations of vorticity close to the trailing edge. Experimental work has shown that synthetic jet actuators can be used to manipulate and control this trapped vorticity. Two different approaches are used to model the action of tangential-blowing synthetic jet actuators mounted near the trailing edge of the airfoil: a detailed model and Reynolds stress synthetic jet (RSSJ) model. The detailed model resolves the synthetic jet dynamics in time while the RSSJ model tries to capture the major effects of the synthetic jet by modeling the changes in the Reynolds stress induced by the actuator, based on experimental PIV data and numerical results from the detailed model. Both models along with the CFD computations in which they are embedded are validated against experimental data. The synthetic jet models have been developed to simulate closed loop flow control of the pitching and plunging of the airfoil, and to this end the RSSJ model is particularly useful since it reduces (by an order of magnitude) the cost of simulating the long-term evolution of the system under control.

Lopez, Omar; Moser, Robert

2008-11-01

351

Large temperature plunges recorded by data loggers at different depths on an Indian Ocean atoll: comparison with satellite data and relevance to coral refuges  

NASA Astrophysics Data System (ADS)

Seawater temperature was recorded at two-hourly intervals for two years (March 2006-March 2008) by six data loggers in Diego Garcia atoll, central Indian Ocean. Loggers were substrate mounted, in two transects of 5, 15 and 25 m depth on a seaward reef and in a lagoonal pass. During the season of mixed but predominantly northwest winds, regular plunges of temperature of 5-7°C occurred with a periodicity of 1-4 days. This partly coincided with the period of greatest annual warming. Temperature fluctuations increased with increasing depth. Temperature traces are compared with HadISST1 and AVHRR satellite-derived temperature data which do not capture the deeper water temperature plunges. Reasons for the regular temperature plunges appear to include both tidal cycles and unidentified, internal waves. This is important for issues of coral refuges, complicating use of satellite-derived temperature data for planning optimal coral reef conservation areas.

Sheppard, C.

2009-06-01

352

Inside the Jet Stream  

NSDL National Science Digital Library

The jet stream is a complex phenomenon involving the interplay between many variables. This resource provides a variety of materials, including Giving Rise to the Jet Stream, which is a simplified introduction that shows what generates the jet stream and why it flows from west to east. The site also contains a five-day view of the jet stream, which is a realistic depiction of how the jet stream flows; a page that provides some answers to frequently asked questions about the jet stream; and a glossary of terms used in the Giving Rise to the Jet Stream feature.

Groleau, Rick

353

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

354

Global Three-dimensional Magnetohydrodynamic Simulations of Black Hole Accretion Disks: X-Ray Flares in the Plunging Region  

NASA Astrophysics Data System (ADS)

We present the results of three-dimensional global resistive magnetohydrodynamic (MHD) simulations of black hole accretion flows. General relativistic effects are simulated by using the pseudo-Newtonian potential. The initial state is an equilibrium model of a torus threaded by weak toroidal magnetic fields. As the magnetorotational instability (MRI) grows in the torus, mass accretes to the black hole by losing angular momentum. We found that in the innermost plunging region, nonaxisymmetric accretion flow creates bisymmetric spiral magnetic fields and current sheets. Mass accretion along the spiral channel creates one-armed spiral density distribution. Since the accreting matter carries in magnetic fields that are subsequently stretched and amplified as a result of differential rotation, current density increases inside the channel. Magnetic reconnection taking place in the current sheet produces slow-mode shock waves that propagate away from the reconnection site. Magnetic energy release in the innermost plunging region could be the origin of X-ray shots observed in black hole candidates. Numerical simulations reproduced soft X-ray excess preceding the peak of the shots, X-ray hardening at the peak of the shot, and hard X-ray time lags.

Machida, Mami; Matsumoto, Ryoji

2003-03-01

355

Jet break-up in nano-suspensions during electrohydrodynamic atomization in the stable cone-jet mode.  

PubMed

This paper reports jet break-up phenomena, which occurs during the electrohydrodynamic atomization (EHDA) of nano-suspensions. We investigated three ethylene glycol-based near-monodisperse suspensions, containing 30 wt% of SiO2 particles sized at 20, 80 and 120 nm. These suspensions were subjected to electrohydrodynamic atomization in the stable cone-jet mode and the jet break-up in each is discussed and compared with those of liquids reported in the literature. PMID:16060154

Jayasinghe, S N; Edirisinghe, M J

2005-06-01

356

The effect of turbulence on the stability of liquid jets and the resulting droplet size distributions. Fourth quarterly technical report, October 1, 1993--December 31, 1993  

SciTech Connect

In this progress report the authors report on progress in making experimental measurements to describe the rheological properties of non-Newtonian fluids. Non-Newtonian liquids exhibit a non linear relationship between the shear stress and the shear rate. A typical time-dependent rheological phenomenon is thixotropy. Thixotropic fluids show a limited decrease in the shear viscosity of the fluid with time under a suddenly applied constant stress. Thixotropic fluids also show a hysteresis loop and a decaying stress on the shear stress-shear rate plot. Here the authors are using a power law model to describe the behavior of such non-Newtonian liquids.

Mansour, A.; Chigier, N.

1993-12-31

357

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

358

Mechanism of stable jet formation in electrohydrodynamic atomization  

Microsoft Academic Search

The mechanism involved in the disruption of a liquid into a spray of droplets when subjected to an intense electric field is poorly understood. At a critical potential the so-called Taylor cone develops, with a fine stable jet issuing from its tip. The first direct observation of jet formation have been made and the results, presented here, demonstrate the role

I. Hayati; A. I. Bailey; Th. F. Tadros

1986-01-01

359

A new flow focusing technique to produce very thin jets  

NASA Astrophysics Data System (ADS)

A new technique is proposed in this paper to produce jets, droplets, and emulsions with sizes ranging from tens of microns down to the submicrometer scale. Liquid is injected at a constant flow rate through a hypodermic needle to form a film over the needle's outer surface. This film flows toward the needle tip until a liquid ligament is steadily ejected. Both the film motion and the liquid ejection are driven by the viscous and pressure forces exerted by a coflowing fluid stream. If this stream is a high-speed gas current, the outcome is a capillary jet which breaks up into droplets due to the Rayleigh instability. Micrometer emulsions are also produced by this instability mechanism when the injected liquid is focused by a viscous liquid stream. The minimum flow rates reached with the proposed technique are two orders of magnitude lower than those of the standard flow focusing configuration. This sharp reduction of the minimum flow rate allows one to form steady jets with radii down to the submicrometer scale. The stability of this new configuration is analyzed experimentally for both gas–liquid and liquid–liquid systems. In most of the cases, the loss of stability must be attributed to the liquid source because the critical Weber (capillary) number for the gas–liquid (liquid–liquid) case was significantly greater than the value corresponding to the convective/absolute instability transition in the jet.

Acero, A. J.; Rebollo-Muñoz, N.; Montanero, J. M.; Gañán-Calvo, A. M.; Vega, E. J.

2013-06-01

360

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

Microsoft Academic Search

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,

Jun-Young Huh

1998-01-01

361

Noise Generation by Gas Jets in a Turbulent Wake.  

National Technical Information Service (NTIS)

Radiation noise is generated by the interaction of gas jets with turbulent liquid. Although this phenomenon has long been known, the mechanism of noise generation and its functional relationship to important parameters are not well understood. No experime...

J. J. Gavigan

1981-01-01

362

Steam-jet Chiller for Army Field Kitchens.  

National Technical Information Service (NTIS)

Report developed under Broad Agency Announcement. This report documents a two-year project aimed at developing steam-jet refrigeration technology that can be integrated with superheated-liquid injection cogeneration (SLIC) cycles in Army kitchens or with ...

D. Brownell

2009-01-01

363

Visualization of supersonic diesel fuel jets using a shadowgraph technique  

NASA Astrophysics Data System (ADS)

High-speed liquid jets have been widely used to cut or penetrate material. It has been recently conjectured that the characteristics of high-speed fuel jets may also be of benefit to engines requiring direct fuel injection into the combustion chamber. Important factors are combustion efficiency and emission control enhancement for better atomization. Fundamental studies of very high velocity liquid jets are therefore very important. The characteristics and behavior of supersonic liquid jets have been studied with the aid of a shadowgraph technique. The high-speed liquid jet (in the supersonic range) is generated by the use of a vertical, single stage powder gun. The performance of the launcher and its relation to the jet exit velocity, with a range of nozzle shapes, has been examined. This paper presents the visual evidence of supersonic diesel fuel jets (velocity around 2000 m/s) investigated by the shadowgraph method. An Argon jet has been used as a light source. With a rise time of 0.07 microseconds, light duration of 0.2 microseconds and the use of high speed Polaroid film, the shadowgraph method can effectively capture the hypersonic diesel fuel jet and its strong leading edge shock waves. This provides a clearer picture of each stage of the generation of hypersonic diesel fuel jets and makes the study of supersonic diesel fuel jet characteristics and the potential for auto-ignition possible. Also, in the experiment, a pressure relief section has been used to minimize the compressed air or blast wave ahead of the projectile. However, the benefit of using a pressure relief section in the design is not clearly known. To investigate this effect, additional experiments have been performed with the use of the shadowgraph method, showing the projectile leaving and traveling inside the nozzle at a velocity around 1100 m/s.

Pianthong, Kulachate; Behnia, Masud; Milton, Brian E.

2001-04-01

364

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

2009-09-04

365

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

366

The entrainment behavior of a turbulent axisymmetric jet in a viscous host fluid  

Microsoft Academic Search

Although turbulent jets have been studied extensively, one configuration that has not received much attention is the viscosity-stratified jet, wherein a turbulent jet of lower viscosity issues into a density-matched host liquid of higher viscosity. We present experimental data for scalar dispersion and two-dimensional velocity measurements in the axial plane of a turbulent axisymmetric jet with a Reynolds number (Re)

Sudhaker Chhabra; Thomas N. Shipman; Ajay K. Prasad

2005-01-01

367

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

368

Steam-water jet analysis. Final report  

Microsoft Academic Search

This report presents the results of a theoretical study on the effects of the steam-water jet emitted from a hypothetical rupture in the high-pressure piping pf a nuclear power plant. A set of calculations is presented, incorporating increasingly complex formulations for mass and momentum exchange between the liquid and vapor flow fields. Comparisons between theory and detailed experimental data are

B. A. Kashiwa; F. H. Harlow; R. B. Demuth; H. M. Ruppel

1984-01-01

369

General review of flashing jet studies  

Microsoft Academic Search

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

Geanette Polanco; Arne Erik Holdø; George Munday

2010-01-01

370

Jet Stability in the Lithium Fall Reactor.  

National Technical Information Service (NTIS)

A preliminary analysis has been made of the various hydrodynamic aspects involved in the stability of a liquid-lithium jet in a laser-fusion reactor, which comprises a part of LLL's laser fusion power-generation concept. Various physical factors that may ...

S. W. Kang

1978-01-01

371

Risk factors of jet fuel combustion products.  

PubMed

Air travel is increasing and airports are being newly built or enlarged. Concern is rising about the exposure to toxic combustion products in the population living in the vicinity of large airports. Jet fuels are well characterized regarding their physical and chemical properties. Health effects of fuel vapors and liquid fuel are described after occupational exposure and in animal studies. Rather less is known about combustion products of jet fuels and exposure to those. Aircraft emissions vary with the engine type, the engine load and the fuel. Among jet aircrafts there are differences between civil and military jet engines and their fuels. Combustion of jet fuel results in CO2, H2O, CO, C, NOx, particles and a great number of organic compounds. Among the emitted hydrocarbons (HCs), no compound (indicator) characteristic for jet engines could be detected so far. Jet engines do not seem to be a source of halogenated compounds or heavy metals. They contain, however, various toxicologically relevant compounds including carcinogenic substances. A comparison between organic compounds in the emissions of jet engines and diesel vehicle engines revealed no major differences in the composition. Risk factors of jet engine fuel exhaust can only be named in context of exposure data. Using available monitoring data, the possibilities and limitations for a risk assessment approach for the population living around large airports are presented. The analysis of such data shows that there is an impact on the air quality of the adjacent communities, but this impact does not result in levels higher than those in a typical urban environment. PMID:15093276

Tesseraux, Irene

2004-04-01

372

Experimental and Computational Simulation of Free Jet Characteristics Under Transverse Field Gradients  

SciTech Connect

In this paper, we present numerical and experimental studies of the behavior of a liquid metal jet in a constant and gradient magnetic field. The experiments were conducted in the Magnetic Torus Liquid Metal MHD flow test facility (MTOR). The experimental results have shown that free jets can be stabilized by the magnetic field. The Lorentz force significantly suppresses the motion of the liquid metal jet and delays the break-up position. Analysis based on linear theory has been applied to understand jet behavior under magnetic fields. In addition, numerical simulation based on B formulation has been performed and compared to the experimental results.

Luo, X.; Ying, A.; Abdou, M. [University of California at Los Angeles (United States)

2003-07-15

373

Dielectric coating dynamics in electrified coaxial jets  

NASA Astrophysics Data System (ADS)

Electrified coaxial jets generated from compound electrified menisci (compound electrosprays) have demonstrated their ability to produce particles with complex core-shell structure (I.G. Loscertales et al., Science, 295, 1695 (2002); JACS, 126, 5376 (2004)). Since at least one of the liquids forming the compound meniscus must be relatively conductive, two configurations are possible: the conducting liquid being in or out. In this work we shall consider the first configuration, whose applications range from simple protection of volatile liquids by non-volatile dielectric liquids to encapsulation by using dielectric polymer melts. Although the scaling law for the electric current transported by the electrified coaxial jets has been recently investigated (Lopez-Herrera et al.,JAS ,34, 535 (2003)), the dynamics of the coating layer is still not completely understood. The aim of this communication is to gain insight on the dependence of the coating thickness on the injected liquid flow rates, the viscosities of both liquids and surface tensions (liquid-liquid and liquid-air).

Marin, Alvaro G.; Loscertales, Ignacio G.; Barrero, Antonio

2006-11-01

374

[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

375

Jet physics in ALICE  

Microsoft Academic Search

This work aims at the performance of the ALICE detector for the measurement of high-energy jets at mid-pseudo-rapidity in ultra-relativistic nucleus--nucleus collisions at LHC and their potential for the characterization of the partonic matter created in these collisions. In our approach, jets at high energy with E_{T}>50 GeV are reconstructed with a cone jet finder, as typically done for jet

Constantinos A. Loizides; Johann Wolfgang von Goethe

2005-01-01

376

Jet Noise: Since 1952  

Microsoft Academic Search

:   Jet noise research was initiated by Sir James Lighthill in 1952. Since that time, the development of jet noise theory has\\u000a followed a very tortuous path. This is, perhaps, not surprising for the understanding of jet noise is inherently tied to the\\u000a understanding of turbulence in jet flows. Even now, our understanding of turbulence is still tenuous. In the

Christopher K. W. Tam

1998-01-01

377

Miniconference on astrophysical jets  

SciTech Connect

This miniconference brought together observers of astrophysical jets, analytic and numerical modelers of both astrophysical jets and spheromaks, and laboratory experimentalists. The purpose of the miniconference was to encourage interaction between these diverse groups and also expose the plasma physics community to the interesting plasma issues associated with astrophysical jets. The miniconference emphasized magnetically driven astrophysical jets and consisted of three half-day sessions. The order of presentation was approximately: observations and general properties, experiments, numerical models, and special topics.

Bellan, P.M. [Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States)

2005-05-15

378

High-speed jetting and spray formation from bubble collapse.  

PubMed

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. PMID:22400617

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

2012-01-17

379

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

380

Quasar Jet Acceleration  

Microsoft Academic Search

We observed radio jets in six lobe-dominated quasars (LDQs) from 1995 to 2008 using the NRAO VLBA at 8.4 and 15 GHz. These observations have tracked jet component positions and velocities over that time period. There is a correlation between apparent jet speed and projected core distance in these LDQs at greater than 99 per cent confidence levels (Hough 2008,

Nicholas Polito; David Hough

2009-01-01

381

Liquid metal fuel combustion mechanics  

Microsoft Academic Search

The modeling of the droplet formation at the gas\\/liquid boundary interface of a gaseous jet injected into a liquid metal bath and the turbulent mixing of the resultant two-phase (gas\\/liquid) mixture is presented as a preliminary to the analysis of the liquid metal fuel combustion problem. The model is used to predict velocity and liquid droplet fraction distributions across the

Tirumalesa Duvvuri

1990-01-01

382

Coaxial atomizer liquid intact lengths  

Microsoft Academic Search

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

Hasan Eroglu; Norman Chigier; Zoltan Farago

1991-01-01

383

Hydroacoustic pulsating jet generator  

NASA Astrophysics Data System (ADS)

A high pressure turbulent jet generator connected to a low pressure hydraulic tube is studied to investigate water hammer in tubes with fast flow variations, generating high pressure pulsating water jets. The pulsating jet generator consists of a tube, a hydraulic valve, a spring, and a water container. The jet is the effect of the combination of turbulent pipe flow with a valve for flow nozzle. The jet pressure depends on specific oscillation impedance and flow velocity variations. For inlet pressure of 0.5 to 2 bar the pressure rises to 40 bar. The described pulsating jet generator is more effective than the earlier model. A piezoelectric pressure controller is used to register pressure signals and high speed photos are made of the jet. Test results are consistent with theoretical calculation.

Unrau, A.; Meier, G. E. A.

1987-04-01

384

Theoretical prediction of the effect of heat transfer parameters on cooling rates of liquid-filled plastic straws used for cryopreservation of spermatozoa.  

PubMed

Heat transfer plays a key role in cryopreservation of liquid semen in plastic straws. The effect of several parameters on the cooling rate of a liquid-filled polypropylene straw when plunged into liquid nitrogen was investigated using a theoretical model. The geometry of the straw containing the liquid was assimilated as two concentric finite cylinders of different materials: the fluid and the straw; the unsteady-state heat conduction equation for concentric cylinders was numerically solved. Parameters studied include external (convection) heat transfer coefficient (h), the thermal properties of straw manufacturing material and wall thickness. It was concluded that the single most important parameter affecting the cooling rate of a liquid column contained in a straw is the external heat transfer coefficient in LN2. Consequently, in order to attain maximum cooling rates, conditions have to be designed to obtain the highest possible heat transfer coefficient when the plastic straw is plunged in liquid nitrogen. PMID:20687454

Sansinen, M; Santos, M V; Zaritzky, N; Baez, R; Chirife, J

385

The breakup of bubbles into jets during submerged gas injection  

Microsoft Academic Search

There has never been any fundamental explanation presented for the transition from the bubbling regime to the jetting regime when gas is injected into liquid at high velocity through submerged tuyeres. This is an important issue in metallurgical processes, since the flow regime is known to influence refining rates, refractory erosion, and the penetration of the liquid into the tuyere.

Y.-F. Zhao; G. A. Irons

1990-01-01

386

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

387

The analysis of the Flibe jets in HYLIFE-II  

SciTech Connect

In the HYLIFE-2 Inertial Confinement Fusion reactor, an array of Flibe (Li{sub 2}BeFe{sub 4}) jets is designed to protect the chamber from the fusion radiation. During the fusion pulse the Flibe jets sustain an instantaneous neutron and X-ray heating. The high energy neutrons from fusion can penetrate deep into the Flibe jets and the sudden increase in internal energy can induce a great pressure rise inside the jets. The subsequent relaxation of the jets is important for the reactor design, because the configuration of the jets will control the subsequent impact forces of vapor and liquid on the reactor chamber wall. The calculations for the lithium jets in the HYLIFE-1 reactor were done previously by using a compressible flow model with a soft sphere equation of state for lithium. A similar equation of state model for Flibe was recently developed. This model allows us to use the same compressible analysis code to calculate the pressure field in the Flibe jets and to estimate the upper bound of the Flibe tension limit. With these results we can analyze the mechanisms of jet relaxation and breakup. 4 refs., 1 fig.

Chen, Xiang M.; Schrock, V.E.; Peterson, P.F.

1991-08-16

388

Vortex interaction of tandem pitching and plunging plates: a two-dimensional model of hovering dragonfly-like flight.  

PubMed

The force evolution and associated vortex dynamics on a nominal two-dimensional tandem pitching and plunging configuration inspired by hovering dragonfly-like flight have been investigated experimentally using time-resolved particle image velocimetry. The aerodynamic forces acting on the flat plates have been determined using a classic control-volume approach, i.e. a momentum balance. It was found that only the tandem phasing of ? = 90° was capable of generating similar levels of thrust when compared to the single-plate reference case. For this tandem configuration, however, a much more constant thrust generation was developed over the cycle. Further examination showed that the force and vortex development on the fore-plate was unaffected by the tandem configuration and that nearly all variations in performance could be attributed to the vortex interaction on the hind-plate. By calculating the trajectory and strength of the hind-plate's trailing-edge vortex, the chain-like vortex interaction mechanism responsible for improved performance at ? = 90° could be identified. The underlying result from this study suggests that the dominant vortex interaction in dragonfly flight is two dimensional and that the spanwise flow generated by root-flapping kinematics is not entirely necessary for efficient propulsion but potentially due to evolutionary restrictions in nature. PMID:21335652

Rival, David; Schönweitz, Dirk; Tropea, Cameron

2011-02-21

389

Construction and validation of a plunge electrode array for three-dimensional determination of conductivity in the heart.  

PubMed

The heart's response to electrical shock, electrical propagation in sinus rhythm, and the spatiotemporal dynamics of ventricular fibrillation all depend critically on the electrical anisotropy of cardiac tissue. Analysis of the microstructure of the heart predicts that three unique intracellular electrical conductances can be defined at any point in the ventricular wall; however, to date, there has been no experimental confirmation of this concept. We report the design, fabrication, and validation of a novel plunge electrode array capable of addressing this issue. A new technique involving nylon coating of 24G hypodermic needles is performed to achieve nonconductive electrodes that can be combined to give moderate-density multisite intramural measurement of extracellular potential in the heart. Each needle houses 13 silver wires within a total diameter of 0.7 mm, and the combined electrode array gives 137 sites of recording. The ability of the electrode array to accurately assess conductances is validated by mapping the potential field induced by a point current source within baths of saline of varying concentration. A bidomain model of current injection in the heart is then used to test an approximate relationship between the monodomain conductivities measured by the array, and the full set of bidomain conductivities that describe cardiac tissue. PMID:18269998

Hooks, Darren A; Trew, Mark L

2008-02-01

390

Correlations of whitecap coverage and gas transfer velocity with microwave brightness temperature for plunging and spilling breaking waves  

SciTech Connect

Bubbles and bubble plumes generated by wind-induced breaking waves significantly enhance the gas exchange across the interface between the ocean and atmosphere under high-wind conditions. Whitcaps, or active spilling wave crests, are the sea-surface manifestation of the bubbles and bubble plumes in the subsurface mixed layer, and the fractional area of the sea surface covered by which has been proposed to correlate linearly with the air-sea gas transfer velocity. The presence of whitecaps substantially increases the microwave brightness temperature of the sea surface. It could be possible to estimate the whitecap coverage from the sea-surface microwave brightness temperature would also be very helpful in developing a remote-sensing model for predicting air-sea gas transfer velocities from microwave brightness temperatures. As a part of an air-water gas exchange experiment conducted in an outdoor surf pool, measurements were made that were designed to investigate the correlation between whitecap coverage and microwave brightness temperature. A mechanical wave maker was located at the deep end of the pool and the generated waves propagate and break towards the shallow end of the pool. Two wave patterns characteristic of plunging and spilling breaking waves at four wave heights from 0.3 m to 1.2 m were produced.

Wang, Qin; Monahan, E.C. [Connecticut Univ., Groton, CT (United States). Marine Sciences Inst.; Asher, W.E. [Battelle/Marine Sciences Lab., Sequim, WA (United States); Smith, P.M. [Naval Research Lab. Detachment, Stennis Space Center, MS (United States)

1995-07-01

391

Jet formation from impulsive cavity collapse  

NASA Astrophysics Data System (ADS)

A cavity at a free liquid/gas interface collapsing due to an impulsive body force forms an intense concentrated jet. This is the paradigm for bubbles bursting at a liquid surface, the collapse of cavitation bubbles near a rigid boundary, collapsing voids following an impact, shaped charges, gravity waves colliding a dam, high amplitude Faraday waves, to quote a few examples among many. We address this problem by considering the axial impact of a cylindrical tube falling by gravity and filled with a liquid wetting the tube wall. Following the impact on a rigid floor, the curvature of the spherical meniscus initially fixed by the tube radius reverses violently, prelude of the birth of a rapid ascending jet. We derive the initial velocity and pressure field around the cavity just after the impact from Euler equations. They are insensitive to liquid viscosity and surface tension, consistently with detailed PIV measurements from high speed movies of the phenomenon. The extension to a cavity no more confined by rigid walls, the dynamics of the resulting jet and its final fragmentation will be considered as well.

Antkowiak, Arnaud; Bremond, Nicolas; Le Dizés, Stéphane; Villermaux, Emmanuel

2006-11-01

392

Interpretation of extragalactic jets  

SciTech Connect

The nature of extragalatic radio jets is modeled. The basic hypothesis of these models is that extragalatic jets are outflows of matter which can be described within the framework of fluid dynamics and that the outflows are essentially continuous. The discussion is limited to the interpretation of large-scale (i.e., kiloparsec-scale) jets. The central problem is to infer the physical parameters of the jets from observed distributions of total and polarized intensity and angle of polarization as a function of frequency. 60 refs., 6 figs.

Norman, M.L.

1985-01-01

393

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

394

Baroclinic splitting of jets  

NASA Astrophysics Data System (ADS)

Whether the split of the Somali jet, sometimes seen on monthly mean streamline analyses, is a climatological or a dynamical feature has been the subject of long-standing debate. This paper explores the dynamical conditions leading to a split jet within the framework of a simple barotropic dynamic system. The initial conditions for the dynamical system, along with three other parameters the jet width, the zonal wavelength, and the latitude of the ?-plane, form a parameter space for the problem consisting of a range of solutions for the evolution of the jet. This paper identifies a region in the parameter space in which these solutions support a splitting of the jet. The width and wavelength of the Somali jet determined from observations are such that for most initial conditions the solutions reside near the boundary in parameter space between the split and non-split regions. It is therefore concluded that the splitting of the Somali jet can be a dynamical feature given the observed jet width and wavelength. Whether a split does or does not occur is determined by the parameters defining the initial zonal mean and perturbation flow in the jet, with the solution being highly sensitive to these initial conditions.

Thompson, A.; Stefanova, L.; Krishnamurti, T. N.

2008-08-01

395

30 CFR Jet - Surface Only  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Surface Only Jet Rotary Jet Piercing Mineral Resources MINE SAFETY AND HEALTH...STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Drilling-Surface and Underground §...

2010-07-01

396

Computer modeling of jet mixing in INEL waste tanks  

SciTech Connect

The objective of this study is to examine the feasibility of using submerged jet mixing pumps to mobilize and suspend settled sludge materials in INEL High Level Radioactive Waste Tanks. Scenarios include removing the heel (a shallow liquid and sludge layer remaining after tank emptying processes) and mobilizing and suspending solids in full or partially full tanks. The approach used was to (1) briefly review jet mixing theory, (2) review erosion literature in order to identify and estimate important sludge characterization parameters (3) perform computer modeling of submerged liquid mixing jets in INEL tank geometries, (4) develop analytical models from which pump operating conditions and mixing times can be estimated, and (5) analyze model results to determine overall feasibility of using jet mixing pumps and make design recommendations.

Meyer, P.A.

1994-01-01

397

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

398

Jet Simulation in a Diesel Engine  

NASA Astrophysics Data System (ADS)

We present a numerical study of the jet breakup and spray formation in a diesel engine by the Front Tracking method. The mechanisms of jet breakup and spray formation of a high speed diesel jet injected through a circular nozzle are the key to design a fuel efficient, nonpolluting diesel engine. We conduct the simulations for the jet breakup within a 2D axis-symmetric geometry. Our goal is to model the spray at a micro-physical level, with the creation of individual droplets. The problem is multiscale. The droplets are a few microns in size. The nozzle is about 0.2 mm in diameter and 1 mm in length. To resolve various physical patterns such as vortex, shock waves, vacuum and track droplets and spray, the Burger-Colella adaptive mesh refinement technique is used. To simulate the spray formation, we model mixed vapor-liquid region through a heterogeneous model with dynamic vapor bubble insertion. The formation of the cavitation is represented by the dynamic creation of vapor bubbles. On the liquid/vapor interface, a phase transition problem is solved numerically. The phase transition is governed by the compressible Euler equations with heat diffusion. Our solution is a new description for the Riemann problem associated with a phase transition in a fully compressible fluid.

Xu, Zhiliang

2005-03-01

399

Cold Water Jets on a Hot Si surface  

Microsoft Academic Search

We are using a femtosecond pump-probe apparatus to study heat transfer when a pulsed jet of liquid water impinges on a hot Pt-coated Si surface (Leidenfrost Effect). The light source in the experiment is a 100 mW Er:fiber laser operating at a wavelength of lambda=1550 nm; the total volume of the pulsed water jet is ˜0.9 mm^3. The temperature change

Ji Yong Park; Chang-Ki Min; David Cahill; Steve Granick

2010-01-01

400

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

401

Jet Blast Hazards.  

National Technical Information Service (NTIS)

The report encompasses a broad review of hazards directly related to inadvertent use of jet thrust power and its adverse effects on other aircraft, airport-ramp personnel, passengers and airport equipment. These jet-blast hazards are illustrated by a repr...

1972-01-01

402

Jet A Volatility Survey.  

National Technical Information Service (NTIS)

In response to the July 1996 TWA Flight 800 disaster, the Federal Aviation Administration (FAA) collected jet fuel samples from domestic and international flights to determine the actual flash point of jet fuel in service. This data was collected to help ...

S. Byrnes

2007-01-01

403

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

404

Aeroacoustics of hot jets  

Microsoft Academic Search

A systematic study has been undertaken to quantify the effect of jet temperature on the noise radiated by subsonic jets. Nozzles of different diameters were tested to uncover the effects of Reynolds number. All the tests were carried out at Boeing's Low Speed Aeroacoustic Facility, with simultaneous measurement of thrust and noise. It is concluded that the change in spectral

K. Viswanathan

2004-01-01

405

Jet Flap Diffuser Ejector.  

National Technical Information Service (NTIS)

The use of a jet flap diffuser for recovery of ejector jet kinetic energy has been investigated in a two-dimensional experiment, utilizing an ejector which employs a Coanda inlet for ninety degree rotation of the primary flow. Performance is compared to a...

G. L. Marlotte M. Alperin

1971-01-01

406

Analytical universal solution of electrified Taylor cone-jets.  

NASA Astrophysics Data System (ADS)

Asymptotic analytical solutions for electrified Taylor cone-jets in electrohydrodynamic atomization of liquids have been recently presented for the cases of (i) large emitted liquid flow rates compared to the minimum one for which a stable cone-jet exists (i.e., large Weber numbers, Ganan-Calvo 1997, Phys. Rev. Lett. 79, 217) and (ii) liquid flow rates very close to the minimum (i.e., small Weber numbers, Cherney 1999, J. Fluid Mech. 378, 167). Now, however, an important criticism on both first complete analytical extensions of Taylor solution presented in the literature is raised: both solutions are unstable or physically inexistent in the asymptotic limits they try to describe, even though both give good approximations to the actual total emitted electric current and jet size in the stable cone-jet parametrical window. In this work we show the way these previous solutions fail and present the first complete analytical solution of Taylor cone-jets for the whole parametrical window of cone-jet stability range, taking into account the role of both the Weber and Ohnesorge numbers in the limits of stability of the physical solution.

Ganan-Calvo, Alfonso M.

1999-11-01

407

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

408

Understanding jet scaling and jet vetos in Higgs searches.  

PubMed

Jet counting and jet vetos are crucial analysis tools for many LHC searches. We can understand their properties from the distribution of the exclusive number of jets. LHC processes tend to show either a distinct staircase scaling or a Poisson scaling, depending on kinematic cuts. We illustrate our approach in a detailed study of jets in weak boson fusion Higgs production. PMID:22400730

Gerwick, Erik; Plehn, Tilman; Schumann, Steffen

2012-01-18

409

The analysis of the Flibe jets in HYLIFE-II  

NASA Astrophysics Data System (ADS)

In the HYLIFE-2 Inertial Confinement Fusion reactor, an array of Flibe (Li2BeFe4) jets is designed to protect the chamber from the fusion radiation. During the fusion pulse the Flibe jets sustain instantaneous neutron and X-ray heating. The high energy neutrons from fusion can penetrate deep into the Flibe jets and the sudden increase in internal energy can induce a pressure rise inside the jets. The subsequent relaxation of the jets is important for the reactor design, because the configuration of the jets will control the subsequent impact forces of vapor and liquid on the reactor chamber wall. The calculations for the lithium jets in the HYLIFE-1 reactor were done previously by using a compressible flow model with a soft sphere equation of state for lithium. A similar equation of state model for Flibe was recently developed. This model allows us to use the same compressible analysis code to calculate the pressure field in the Flibe jets and to estimate the upper bound of the Flibe tension limit.

Chen, Xiang M.; Schrock, V. E.; Peterson, P. F.

1991-08-01

410

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

411

Laser-induced jet formation and droplet ejection from thin metal films  

NASA Astrophysics Data System (ADS)

An experimental study of femtosecond laser-induced jet formation and droplet ejection from thin metal films is presented. These processes are compared to liquid jet formation during laser-induced forward transfer of viscous liquids. As a result of this comparison, a mechanism explaining the main features of laser processing of thin metal films is proposed. According to this mechanism, laser-induced generation of a molten bump and its collapse are similar to the collapse of cavitation bubbles on a liquid-air interface. Material criteria required for realization of the jetting process are discussed and supported by experimental observations.

Kuznetsov, Arseniy I.; Unger, Claudia; Koch, Jürgen; Chichkov, Boris N.

2012-03-01

412

Modeling atomization of a round water jet by a high-speed annular air jet based on the self-similarity of droplet breakup  

Microsoft Academic Search

Based on the self-similarity of droplet breakup in the secondary atomization region, the atomization process of coaxial air-blast atomizer has been investigated. The relationship of Sauter mean diameter (SMD) with the effects of gas jet velocity, liquid jet velocity and diameter and liquid\\/gas mass flux ratio was obtained according to the breakup time and motion characteristic of droplet in air

De-Jun Jiang; Hai-Feng Liu; Wei-Feng Li; Jian-Liang Xu; Fu-Chen Wang; Xin Gong

413

Energy loss of swift protons in liquid water and ethanol  

NASA Astrophysics Data System (ADS)

Energy loss measurement has been performed for the first time for MeV energy hydrogen ions passing through a liquid jet target produced by our newly developed liquid-in-vacuum apparatus. Liquid jet targets of water and ethanol were ejected into vacuum through an aperture of 20 ?m in diameter. Preliminary experimental results of energy loss spectra are reported. It was found that the energy loss of swift protons in liquids are slightly different from the conventional stopping power data obtained from the SRIM code. However, this discrepancy is possibly attributable to our incorrect estimation of the liquid jet diameter.

Itoh, A.; Kaneda, M.; Satoh, S.; Ishii, K.; Tsuchida, H.

2006-04-01

414

Bubble-Jets in Gravitational Fields (APS DFD Video V060)  

Microsoft Academic Search

We show visualizations of the gravity-induced jets formed by spherical bubbles collapsing in liquids subjected to normal gravity, micro-gravity, and hyper-gravity. These observations demonstrate that gravity can have a significant effect on cavitation bubbles. An analysis of the gravity-induced jets uncovers a scaling law between the size of bubble-induced jets and the non-dimensional parameter grad(p)*R0\\/p, where R0 is the maximal

Danail Obreschkow; Marc Tinguely; Nicolas Dorsaz; Philippe Kobel; Aurele de Bosset; Mohamed Farhat

2011-01-01

415

Heat transfer characteristics of a slot jet impinging on a semi-circular convex surface  

Microsoft Academic Search

Surface heat transfer characteristics of a heated slot jet impinging on a semi-circular convex surface have been investigated by using the transient heating liquid crystal technique. Free jet velocity, turbulence and temperature characteristics have been determined by using a combination of an X-wire and a cold wire anemometry. The parametric effects of jet Reynolds number (ReW) ranging from 5600 to

T. L. Chan; C. W. Leung; K. Jambunathan; S. Ashforth-Frost; Y. Zhou; M. H. Liu

2002-01-01

416

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

417

Establishment of Analytical Model for Peak Temperature Within a Sodium-Water Reaction Jet, (I)  

Microsoft Academic Search

In order to establish an analytical model for the peak temperature within a sodium-water reaction jet, an analytical and theoretical investigation of an inert-hot-gas jet injected into a bath of cold liquid was performed as the first step. The laboratory study involved measurement of the centerline temperatures within hot N2-gas jets in water and in volatile refrigerant Suva-123. An integral

Michael EPSTEIN; Hans K. FAUSKE; Naoki YOSHIOKA; Masanori TASHIMO; Hiroshi SAKABA; Shoji KOTAKE

2005-01-01

418

Air entrainment through viscous liquid.  

NASA Astrophysics Data System (ADS)

We are interested in the impact of a jet of a viscous fluid in a bath of the same liquid. Depending on the speed of the jet, the liquid air interface adopts different shapes 1) at low velocity of the jet, the liquid air interface is not deformed and the base of the jet broadens, hence connecting the two media 2) at intermediate speed, there is an inverse meniscus located on the surface of the bath, and the jet is not deformed. 3) Above a threshold speed a thin sheet of air is dragged into the bath by the jet, in a trumpet-like form. In order to measure properly this speed, we use as experimental set up a rotating solid cylinder half-immersed in a bath. When this cylinder is put in rotation, the film of the viscous fluid dragged at one side of the roller (and at the same speed of the roller) encounters the bath of liquid at the other side with the speed of the roller. At this point, a cusp can be observed, below a threshold velocity Vc. Above this threshold, a film of the upper phase is entrained. We measure Vc and focus on its dependence on the viscosities of the two fluids. We show in particular that Vc depends on the logarithmic of the ratio between the two viscosities.

Lorenceau, Elise; Restagno, Frederic; Quere, David

2002-11-01

419

Liquid Sampling System.  

National Technical Information Service (NTIS)

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...

L. L. Larson

1984-01-01

420

Jet Physics at CDF  

SciTech Connect

Jets have been studied by the CDF Collaboration [1] as a means of searching for new particles and interactions, testing a variety of perturbative QCD predictions, and providing input for the global parton distribution function (PDF) fits. Unless otherwise indicated below, the jets were reconstructed using a cone algorithm [2] with cone radius R = 0.7 from data taken at the Fermilab Tevatron collider in Run 2, 2001-2003, with {radical}s = 1.96 TeV. Central jets, in the pseudorapidity range relative to fixed detector coordinates 0.1 < |{eta}| < 0.7, are used.

Sally Seidel

2004-06-28

421

Numerical simulation of electrospray in the cone-jet mode.  

PubMed

We present a robust and computationally efficient numerical scheme for simulating steady electrohydrodynamic atomization processes (electrospray). The main simplification assumed in this scheme is that all the free electrical charges are distributed over the interface. A comparison of the results with those calculated with a volume-of-fluid method showed that the numerical scheme presented here accurately describes the flow pattern within the entire liquid domain. Experiments were performed to partially validate the numerical predictions. The simulations reproduced accurately the experimental shape of the liquid cone jet, providing correct values of the emitted electric current even for configurations very close to the cone-jet stability limit. PMID:23005852

Herrada, M A; López-Herrera, J M; Gañán-Calvo, A M; Vega, E J; Montanero, J M; Popinet, S

2012-08-08

422

Optimized Parameters for a Mercury Jet Target  

SciTech Connect

A study of target parameters for a high-power, liquid mercury jet target system for a neutrino factory or muon collider is presented. Using the MARS code, we simulate particle production initiated by incoming protons with kinetic energies between 2 and 100 GeV. For each proton beam energy, we maximize production by varying the geometric parameters of the target: the mercury jet radius, the incoming proton beam angle, and the crossing angle between the mercury jet and the proton beam. The number of muons surviving through an ionization cooling channel is determined as a function of the proton beam energy. We optimize the mercury jet target parameters: the mercury jet radius, the incoming proton beam angle and the crossing angle between the mercury jet and the proton beam for each proton beam energy. The optimized target radius varies from about 0.4 cm to 0.6 cm as the proton beam energy increases. The optimized beam angle varies from 75 mrad to 120 mrad. The optimized crossing angle is near 20 mrad for energies above 5 GeV. These values differ from earlier choices of 67 mrad for the beam angle and 33 mrad for the crossing angle. These new choices for the beam parameters increase the meson production by about 20% compared to the earlier parameters. Our study demonstrates that the maximum meson production efficiency per unit proton beam power occurs when the proton kinetic energy is in the range of 5-15 GeV. Finally, the dependence on energy of the number of muons at the end of the cooling channel is nearly identical to the dependence on energy of the meson production 50 m from the target. This demonstrates that the target parameters can be optimized without the additional step of running the distribution through a code such as ICOOL that simulates the bunching, phase rotation, and cooling.

Ding, X.; Kirk, H.

2010-12-01

423

The Jets of Enceladus: Locations, Correlations with Thermal Hot Spots, and Jet Particle Vertical Velocities  

NASA Astrophysics Data System (ADS)

High resolution images of Enceladus and its south polar jets taken with the Cassini ISS cameras in the last year have provided an opportunity for detailed study of the jetting phenomenon and its relationship to features and thermal hot spots on the moon’s south polar terrain. We have identified ~ 30 individual jets in a series of images, ranging from 43 to 100 m per pixel, taken in November 2009. All jets are found to be erupting through `tiger stripe’ fractures that cross the south polar terrain. The most intense jetting activity generally corresponds to the hottest regions on the fractures. One of the brightest, most prominent jets observed in this image series vents from a region on the Damascus Sulcus fracture that was imaged at 16 m/pixel during Cassini’s August 13, 2010 flyby; it is also one of the hottest places found so far on the south polar region. Several jets were selected for dynamical modeling. These were jets whose source regions were on the limb as seen from Cassini, allowing extraction of brightness profiles down to a few hundred meters of the surface. We infer the velocity distribution of the particles as they leave the surface by modeling the integrated brightness vs. altitude. The particles are assumed to follow ballistic trajectories, and their contribution to the brightness in each thin layer is proportional to the time that they spend in the layer. We find slow jets, fast jets, and jets in between. After a rapid ~ 2-km-scale-height decrease near the surface, the most prominent jet (mentioned above) extends with constant integrated brightness to the edge of the image 25 km above the surface; some of the particles in this jet appear to have mean velocities that exceed the 235 m/sec escape speed from Enceladus. Further analysis of higher-altitude images from the November flyby is in progress to verify this result. The integrated brightness of slow jets falls off with a scale height of 5 km or less, implying mean vertical velocities of order 30 m/s or less, much less than either the escape speed or the thermal speed for a temperature of 273 K. From the collimation of the vapor in the jets, the Cassini UVIS team infers vertical velocities of 1000 m/s or more [Hansen et al. (2008) Nature 456, 477-479]. Schmidt et al. [(2008) Nature 451, 685-688] account for the slow particle speeds by invoking collisions with the walls of the vent. Ingersoll and Pankine [(2010) Icarus 206, 594-607] invoke short distances during which the gas velocity is high; the particles don’t have time reach escape speed. The third possibility is that the particles are so large that the gas cannot accelerate them to escape speed. This possibility is testable with Cassini ISS high-resolution images, which span phase angles up to 176 degrees and wavelengths from UV to near-IR. Our ultimate goal is to test models of how the jets form. The particles form either by condensing directly from vapor, by spallation from the icy walls of the vent, or by freezing of liquid water droplets. Images collected by Cassini thus far will help us choose among the possibilities.

Porco, C.; Ingersoll, A. P.; Dinino, D.; Helfenstein, P.; Roatsch, T.; Mitchell, C. J.; Ewald, S. P.

2010-12-01

424

Supersonic Air Flow due to Solid-Liquid Impact  

Microsoft Academic Search

A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1m\\/s, this air jet attains supersonic speeds already when the cavity is

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

2010-01-01

425

Supersonic Air Flow due to Solid-Liquid Impact  

Microsoft Academic Search

A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1??m\\/s, this air jet attains supersonic speeds already when the cavity is

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

2010-01-01

426

Dynamics and Breakup of Pulse Microjets of Polymeric Liquids  

Microsoft Academic Search

The possibilities of controlling the dynamics and breakup of pulsed low-viscosity liquid microjets by means of small amounts of polymeric additives are considered. Significant differences between the breakup of pulse jets of Newtonian and viscoelastic polymeric liquids are recorded by means of high-speed photography. In flight a standard Newtonian fluid jet fragments into many secondary droplets. Depending on the molecular

A. V. Bazilevskii; J. D. Meyer; A. N. Rozhkov

2005-01-01

427

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

428

Transient and steady-state measurement of boiling heat transfer from impinging jets  

Microsoft Academic Search

Free-surface liquid jets are frequently used in primary metals processing operations to control cooling rates, thereby influencing the metallurgical and mechanical properties of finished products. The hydrodynamics and heat transfer of jet impingement boiling from high temperature surfaces (exceeding the temperature corresponding to maximum heat flux) are still poorly understood and modeled. In an effort to address these deficiencies, this

David Eric Hall

1998-01-01

429

The spout of air jets upwardly injected into a water bath  

Microsoft Academic Search

The spout region of gas jets in liquids has received little attention, although it has both theoretical and practical significance. In this study, the spout of upwardly injected gas jets in water was characterized experimentally in terms of gas fraction, bubble frequency, and axial velocity distributions for ultimate incorporation into turbulent recirculating flow models. The measurements were made with a

V. Sahajwalla; A. H. Castillejos; J. K. Brimacombe

1990-01-01

430

Conceptual design, development and preliminary tests of a Compact Neutron Spectrometer for the JET experiment  

Microsoft Academic Search

The Compact Neutron Spectrometer (CNS) is a Joint European Torus (JET) Enhancement Project, devoted to measure the neutron emission spectra in different plasmas scenarios. The results obtained by CNS during next JET campaigns will contribute to the development of neutron spectrometers suitable for applications in the International Thermonuclear Experimental Reactor (ITER). The main components of the instrument are a liquid

Francesco Belli; Basilio Esposito; Luca Giacomelli; Andre Luecke; Daniele Marocco; Marco Riva; Helmut Schuhmacher; Brian Syme; Kai Tittelmeier; Andreas Zimbal

2009-01-01

431

Metal and polymer melt jet formation by the high-power laser ablation  

Microsoft Academic Search

The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming

Jack J. Yoh; Ardian B. Gojani

2010-01-01

432

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

433

The hydraulic analysis of cylindrical Flibe jets in a HYLIFE-2 ICF reactor  

Microsoft Academic Search

In HYLIFE, a conceptual design of inertial confinement fusion reactors, a liquid jet array is proposed to protect the reactor chamber from fusion radiation. During the pulse of fusion, the jets will sustain severe neutron and x-ray heating. Since the high energy neutrons can penetrate the material fairly well, they induce a nearly uniform and very large pressure rise within

X. M. Chen; V. E. Schrock; P. F. Peterson

1992-01-01

434

In situ x-ray diffraction measurements of the capillary fountain jet produced via ultrasonic atomization  

Microsoft Academic Search

In situ x-ray diffraction measurements were carried out for investigating the liquid structure in the ultrasonic fountain jet to consider the mechanism of the ``ultrasonic ethanol separation'' reported by Sato et al. [J. Chem. Phys. 114, 2382 (2001)]. For pure liquids (water and ethanol), it was found that the high frequency ultrasound does not affect the liquid structure microscopically. For

Yohko F. Yano; Junya Douguchi; Atsushi Kumagai; Takao Iijima; Yukinobu Tomida; Toshiaki Miyamoto; Kazuo Matsuura

2006-01-01

435

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

436

Coiling of viscous jets  

NASA Astrophysics Data System (ADS)

A stream of honey poured from a sufficient height forms a series of helical coils as it approaches a piece of toast. I have studied the dynamics of this instability using an asymptotic theory for a thin inertia-free viscous jet that deforms under the action of gravity and surface tension. The jet's shape is described by the radius of its cross-section and the curvature and torsion of its axis, as functions of arclength and time. Such a jet can experience four distinct modes of deformation: stretching/shortening; bending in the local osculating plane; bending out of the osculating plane; and twisting. The instantaneous response of the jet to applied loads is described by a twelfth-order system of coupled ordinary differential equations, comprising the equations of global (integrated) force and moment balance together with appropriate constitutive relations for the stress resultants and bending moments. The temporal evolution of the jet's radius and axial shape is described by additional kinematic equations of hyperbolic type. The equations are solved numerically using a relaxation method for the instantaneous response and a staggered leapfrog scheme for the time evolution. The critical feature of the dynamics is a bifurcation from a state of ``forced'' coiling in which buoyancy forces are negligible to one of ``free'' coiling in which those forces are dominant. I will present scaling laws for the coiling frequency in both regimes, as functions of the pouring height, the flow rate, the initial jet radius, and the fluid properties.

Ribe, Neil

2002-11-01

437

The elusive optical jets  

SciTech Connect

Imaging observations in the U band of eight radio galaxies are presented. No optical counter-part to the radio jets are found. For the three radio galaxies 3C 147, 3C 279, and 3C 433, it is shown that the radio to optical spectral index of the jet is significantly higher than the typical values found in the three best-known opticals jets (M87, 3C 273, and 3C 66B). It is concluded that the cutoff frequencies are lower than 10 to the 14th Hz in these cases. For the 3C 31 jet, data are consistent with the radio to optical spectral index being comparable to the typical values. This result is in contradiction with the detection of the optical jet in the B band by Butcher et al. (1980). Finally, the lower limit on the radio to optical spectral index obtained for the four other radio jets of the sample is still consistent with the typical values. 35 refs.

Fraix-Burnet, D.; Nieto, J.L.; Golombek, D.; Macchetto, F.; Lelievre, G. (Observatoire Midi-Pyrenees, Toulouse (France) Space Telescope Science Institute, Baltimore, MD (USA) Paris Observatoire (France))

1991-01-01

438

Numerical study on mixing of oscillating quasi-planar jets with low Reynolds number turbulent stress and heat flux equation models  

Microsoft Academic Search

A comparative investigation was conducted on the mechanistic numerical simulation of mixing of non-isothermal, quasi-planar jets incorporating low Reynolds number turbulent stress and heat flux equation models (LRSFM) and an experiment. A water test facility with three vertical jets, the unheated in between two heated jets, simulated convective mixing and temperature fluctuations expected at the outlet of a liquid metal

Motohiko Nishimura; Akira Tokuhiro; Nobuyuki Kimura; Hideki Kamide

2000-01-01

439

The Middle School Plunge  

ERIC Educational Resources Information Center

|Policymakers nationwide continue to wrestle with a basic question: At what grade level should students move to a new school? In the most common grade configuration in American school districts, public school students make two school transitions, entering a middle school in grade 6 or 7 and a high school in grade 9. This pattern reflects the…

West, Martin; Schwerdt, Guido

2012-01-01

440

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

441

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

442

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

443

Integrated coke, asphalt and jet fuel production process and apparatus  

SciTech Connect

This patent describes a process and apparatus for the production of coke, asphalt and jet fuel from a feed of fossil fuels containing volatile carbon compounds. 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, J.Y.

1991-04-16

444

The breakup of bubbles into jets during submerged gas injection  

Microsoft Academic Search

There has never been any fundamental explanation presented for the transition from the bubbling regime to the jetting regime\\u000a when gas is injected into liquid at high velocity through submerged tuyeres. This is an important issue in metallurgical processes,\\u000a since the flow regime is known to influence refining rates, refractory erosion, and the penetration of the liquid into the\\u000a tuyere.

Y.-F. Zhao; G. A. Irons

1990-01-01

445

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

446

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

447

Negatively buoyant starting jets  

NASA Astrophysics Data System (ADS)

The initial development of negatively buoyant jets has been investigated experimentally and numerically, focusing on the role played by gravity in the evolution of the leading vortex ring. Under the experimental conditions considered in this work, the densimetric Froude number, Fr=?jUj2/[(?0-?j)gD], which represents the ratio between the jet momentum and the buoyancy forces, emerges as the most relevant parameter characterizing the dynamics of the flow. Two different flow regimes have been observed depending on the Froude number: for sufficiently small Fr, the vortex ring generated initially is pushed radially away by gravity forces before it has time to detach from the shear layer originating at the orifice. On the other hand, when the Froude number is larger than a critical value, Fr>Frc~1, the vortex ring detaches from the injection orifice and propagates downstream into the stagnant ambient followed by a trailing jet until it eventually reaches a maximum penetration depth. In order to clarify the mechanisms leading to the transition between the two regimes, and to gain physical understanding of the formation dynamics of negatively buoyant starting jets, the total and the vortex circulation, as well as the trajectory of the vortex center, have been measured and compared to the case of neutrally buoyant jets. Finally, based on the experimental measurements and on the results of the numerical computations, a kinematic model that successfully describes the evolution of both total circulation and vortex trajectory is proposed.

Marugán-Cruz, C.; Rodríguez-Rodríguez, J.; Martínez-Bazán, C.

2009-11-01

448

Admissible Reynolds Numbers for Poiseuille Flow in Jet Viscometer Orifices  

Microsoft Academic Search

At low Reynolds numbers for which the flow through a jet viscometer orifice strictly obeys the Poiseuille equation, the effective hydrodynamic length L0 which may be calculated from the volume flow rate, the applied pressure difference, the radius of the orifice, and the density and low rate of shear viscosity of the liquid is much larger than the length L

R. Schnurmann; P. A. Davies

1975-01-01

449

Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.  

PubMed

Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw. PMID:22225685

Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

2012-01-05

450

Polymer-induced turbulence modifications in an impinging jet  

NASA Astrophysics Data System (ADS)

This effort explores the impact of dilute polymer solutions on the turbulence characteristics in a submerged liquid impinging-jet configuration. Turbulent impinging jets are commonly used in technological applications such as drying, scouring, cooling, or heating due to an enhancement in transport characteristics in the impingement region under certain nozzle-to-wall configurations. Previous efforts have identified significant turbulence modifications in the presence of dilute concentrations of polymer in both bounded and unbounded flows, though the former has received considerably more attention. To this end, particle-image velocimetry measurements were taken for an axisymmetric turbulent impinging jet with a nozzle-to-wall distance H/ D = 6.8 and nominal Reynolds number of 26,000. Measurements were performed for both plain water and dilute polymer solutions of polyethylene oxide at concentrations of 50 and 100 ppm. The mean and turbulence characteristics of these three flows are contrasted and it is observed that the two polymer solutions modify both the mean and turbulent characteristics of the jet in all three regions of interest (the free-jet, impingement, and wall-jet regions). Of interest, the 50 ppm case yielded a slight suppression of the turbulence in the free-jet region accompanied by a longer axial length of the potential core compared to the case of plain water. In contrast, the 100 ppm case exhibits clear enhancement of the turbulence in the free-jet region and a shortening of the potential core length. The effect of polymer was opposite in the impingement and wall-jet regions wherein the turbulence was slightly suppressed in the 100 ppm case in a manner consistent with the onset of the Toms effect in this wall-bounded region of the flow.

Mejia-Alvarez, R.; Christensen, K. T.

2012-05-01

451

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

2011-05-20

452

Results on inclusive jets and jet properties  

SciTech Connect

We report on a measurement of the inclusive jet cross section in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider corresponding to an integrated luminosity of 0.70 fb{sup -1}. Detailed studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented, and the cross section measurements are found to be in good agreement with next-to-leading order QCD calculations.

Voutilainen, Mikko Antero; /Nebraska U. /Helsinki Inst. of Phys. /DAPNIA, Saclay

2008-04-01

453

Air entrainment in spray jets  

NASA Astrophysics Data System (ADS)

The entrainment of air into spray jets has been considered. Measurements have been made of the air entrainment into spray jets and compared with the results of a simple model of air entrainment. Comparison of the results from free air jet experiments with that from sprays indicate that a free air jet is able to entrain as much as 50 times more fluid than its spray counterpart over a similar length.

MacGregor, S. A.

1991-09-01