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1

Free jet expansion and gas entrainment characteristics of a plunging liquid jet  

Microsoft Academic Search

The change in effective jet diameter is measured as a function of free jet length for vertical liquid jets passing through air. The data are incorporated into a model to predict the rate of gas entrainment for a liquid jet plunging into a confined column of liquid. In the model it was assumed that the total gas entrainment rate included

C. D. Rielly

1996-01-01

2

Plunging jet characteristics of plunging breakers  

Microsoft Academic Search

With plunging breaking waves, air bubble entrainment is caused by the top of the wave forming a plunging jet and entraining air when it impacts the water in front of the wave. The potential for air bubble entrainment is related directly to the plunging jet impact characteristics. New experiments were performed in a two-dimensional wave flume. The breaking process was

Hubert Chanson; Lee Jaw-Fang

1997-01-01

3

Study of Air Entrainment by a Horizontal Plunging Liquid Jet  

Microsoft Academic Search

The process of air entrainment following the impact of an initially horizontal circular water jet on a pool of water has been studied computationally and experimentally. It has been found that the entrainment of air cavities in the near field region is periodic, not continuous as reported in earlier studies. The simulations are based on a Volume-of-Fluid methodology with interfacial

Mario Trujillo; Suraj Deshpande; Xiongjun Wu; Georges Chahine

2009-01-01

4

Simultaneous removal of carbonaceous and nitrogenous pollutants by a plunging liquid jet bioreactor with crossflow filtration operated under intermittent aeration  

Microsoft Academic Search

Simultaneous removal of total organic carbon (TOC) and nitrogen (T-N) by a plunging liquid jet bioreactor was investigated for small-scale treatment of domestic wastewater. The bioreactor was operated under suspended growth and attached growth conditions and intermittent aeration to carry out both nitrification and denitrification processes in one vessel. In the suspended growth system, TOC removal efficiency was about 90%

Kazuaki Yamagiwa; Yuichi Oohira; Akira Ohkawa

1995-01-01

5

An Experimental Study of Individual Air Bubble Entrainment at a Planar Plunging Jet  

Microsoft Academic Search

t the impact of a plunging liquid jet with a receiving pool, air bubbles may be entrained if the impact velocity exceeds a critical velocity. New experiments were performed in a two-dimensional plunging jet. Theow conditions near the inception of air entrainment were investigated. Two mechanisms of air entrainment were visualized at low jet velocities: by elongated air cavity and

P. D. Cummings; H. Chanson

1999-01-01

6

Xanthan production in a plunging jet reactor  

Microsoft Academic Search

A plunging jet reactor (0.04–0.08 m3) was used for the production of the exopolysaccharide xanthan with Xanthomonas campestris. The microorganism was not affected by the pump shear force. Similar specific growth rates and xanthan space-time yields to those in other reactor types were achieved at much lower specific power input. The better oxygen sorption efficiency in the jet reactor overcompensated

Ahmed Zaidi; Purnendu Ghosh; Adrian Schumpe; Wolf-Dieter Deckwer

1991-01-01

7

Physical modelling and similitude of air bubble entrainment at vertical circular plunging jets  

Microsoft Academic Search

When a plunging jet impinges into a pool of liquid, air bubble entrainment takes place if the inflow velocity exceeds a threshold velocity. This study investigates air entrainment and bubble dispersion in the developing flow region of vertical circular plunging jets. Three scale models were used and detailed air–water measurements (void fraction, bubble count rate, bubble sizes) were performed systematically

H. Chanson; S. Aoki; A. Hoque

2004-01-01

8

Laminar Plunging Jets - Interfacial Rupture and Inception of Entrainment  

NASA Astrophysics Data System (ADS)

Interfacial rupture and entrainment are commonly observed, e.g., air bubbles within a container being filled with water from a faucet. The example involves a liquid jet (density, rho, and viscosity, ?) plunging into a receiving pool of liquid. Below a critical liquid-jet velocity, the interface develops a cusp-like shape within the receiving pool. The cusp becomes sharper with increasing liquid-jet velocity, and at a critical velocity ( Vc), the interface between the liquid and the surrounding fluid (density, rho0, and viscosity, ?0) ruptures. Interfacial tension (sigma) can no longer preserve the integrity of the interface between the two immiscible fluids, and the plunging jet drags/entrains surrounding fluid into the receiving pool. Subsequently, the entrained fluid breaks up into bubbles within the receiving pool. The focus of this dissertation is the numerical prediction of the critical entrainment inception velocities for laminar plunging jets using the Volume-Of-Fluid (VOF) method, a Computational Fluid Dynamics (CFD) method to simulate multi-fluid flows. Canonical to bottle-filling operations in the industry is the plunging-jet configuration -- the liquid jet issues from a nozzle and plunges into a container filled with liquid. Simulations of this configuration require capturing flow phenomena over a large range of length scales (4 orders of magnitude). Results show severe under-prediction of critical entrainment velocities when the maximum resolution is insufficient to capture the sharpening, and eventual rupture, of the interfacial cusp. Higher resolutions resulted in computational meshes with prohibitively large number of cells, and a drastic reduction in time-step values. Experimental results in the literature suggest at least a 100-fold increase in the smallest length scale when the entrained fluid is a liquid instead of air. This narrows the range of length scales in the problem. We exploit the experimental correlation between critical capillary number, Cac = ??Vc/sigma and viscosity ratio, ?0/? in postulating an alternate approach involving scaling of the pertinent physics by using liquids as entrained fluids. The scaling approach is tested using a rotating cylinder placed at the interface between two fluids. A mesh-independence study using successively finer meshes predicted critical entrainment velocity values within about 1% of each other. Numerical predictions compared well with experimental data, with less than 1% difference in the case where exact experimental data was available, and a maximum of 6% difference for cases where experimental data was extrapolated to make the comparison. These results lend credibility to our approach. The effect of densities of the two fluids manifests as buoyancy force at the interfacial cusp. Remarkably, contrary to a priori notions, our simulation results showed that as Deltarho increased, the effect of buoyancy decreased relative to other forces at the interfacial cusp. Finally, we proposed an empirical correlation between Cac and ? 0/? which allows extrapolation of critical entrainment conditions between the rotating-cylinder configuration (with liquids being entrained) to the plunging-jet configuration (with air being entrained). The primary contribution of this research is the physics-based scaling approach utilized to overcome the simulation challenges posed by the physics of interface rupture and entrainment.

Kishore, Aravind

9

Modeling air entrainment in plunging jet using 3DYNAFS  

E-print Network

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 plunging onto a pool of stationary water was numerically studied by using the 3DYNAFS software suit. The flow field is simulated by directly solving the Navier-Stokes equations through the viscous module, 3DYNAFS-VIS, using a level set method for capturing the free surface. The breakup of entrained air pockets and the resulting bubbly flow were modeled by coupling 3DYNAFS-VIS with a Lagrangian multi-bubble tracking model, 3DYNAFS-DSM (Hsiao & Chahine, 2003), which emits bubbles into the liquid according to local liquid/gas interface flow conditions based on the sub-grid air entrainment modeling proposed by Ma et al. (2011), and tracks all bubbles in t...

Hsiao, Chao-Tsung; Wu, Xiongjun; Chahine, Georges L

2011-01-01

10

Depth of penetration of bubbles entrained by a plunging water jet Christophe Clanet and Juan C. Lasheras  

E-print Network

Depth of penetration of bubbles entrained by a plunging water jet Christophe Clanet and Juan C a wide range of jet diameters, velocities, and plunging angles. © 1997 American Institute of Physics. S surface; e.g., a jet plunging into a pool, a breaking wave plunging in the ocean, a droplet impinging

Clanet, Christophe

11

Air entrainment by a plunging jet under intermittent vortex conditions  

E-print Network

This fluid dynamic video entry to the 2011 APS-DFD Gallery of Fluid Motion details the transient evolution of the free surface surrounding the impact region of a low-viscosity laminar liquid jet as it enters a quiescent pool. The close-up images depict the destabilization and breakup of the annular air gap and the subsequent entrainment of bubbles into the bulk liquid.

Kim, Kevin Jin; Li, Kevin; Kiger, Ken T

2011-01-01

12

The hydraulic bump: The surface signature of a plunging jet M. Labousse and J. W. M. Bush  

E-print Network

The hydraulic bump: The surface signature of a plunging jet M. Labousse and J. W. M. Bush Citation://pof.aip.org/authors #12;PHYSICS OF FLUIDS 25, 094104 (2013) The hydraulic bump: The surface signature of a plunging jet M a falling jet of fluid strikes a horizontal fluid layer, a hydraulic jump arises downstream of the point

13

FIELD MANUAL FOR PLUNGING WATER JET USE IN OIL SPILL CLEANUP  

EPA Science Inventory

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

14

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

NASA Astrophysics Data System (ADS)

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

Deshpande, Suraj S.; Trujillo, Mario F.

2011-11-01

15

Air entrapment and air bubble dispersion at two-dimensional plunging water jets  

Microsoft Academic Search

Air–water bubbly flows are encountered in numerous engineering applications. One type of air–water shear flow, the developing flow region of a plunging jet, is discussed in the light of new experimental evidence. Distributions of air concentration and mean air–water velocity, and bubble chord length distributions are presented for inflow velocities ranging from 2 to 8m\\/s. The results indicate that the

T. Brattberg; H. Chanson

1998-01-01

16

The hydraulic bump: The surface signature of a plunging jet  

E-print Network

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, Matthieu

2014-01-01

17

Enhancing liquid jet erosion  

Microsoft Academic Search

Process and apparatus for enhancing the erosive intensity of a high velocity liquid jet when the jet is impacted against a surface for cutting, cleaning, drilling or otherwise acting on the surface. A preferred method comprises the steps of forming a high velocity liquid jet, oscillating the velocity of the jet at a preferred Strouhal number, and impinging the pulsed

Johnson V. E. Jr

1984-01-01

18

On the seawater temperature dependence of the sea spray aerosol generated by a continuous plunging jet  

NASA Astrophysics Data System (ADS)

Breaking waves on the ocean surface produce bubbles which, upon bursting, deliver seawater constituents into the atmosphere as sea spray aerosol particles. One way of investigating this process in the laboratory is to generate a bubble plume by a continuous plunging jet. We performed a series of laboratory experiments to elucidate the role of seawater temperature on aerosol production from artificial seawater free from organic contamination using a plunging jet. The seawater temperature was varied from -1.3°C to 30.1°C, while the volume of air entrained by the jet, surface bubble size distributions, and size distribution of the aerosol particles produced was monitored. We observed that the volume of air entrained decreased as the seawater temperature was increased. The number of surface bubbles with film radius smaller than 2 mm decreased nonlinearly with seawater temperature. This decrease was coincident with a substantial reduction in particle production. The number concentrations of particles with dry diameter less than ˜1 ?m decreased substantially as the seawater temperature was increased from -1.3°C to ˜9°C. With further increase in seawater temperature (up to 30°C), a small increase in the number concentration of larger particles (dry diameter >˜0.3 ?m) was observed. Based on these observations, we infer that as seawater temperature increases, the process of bubble fragmentation changes, resulting in decreased air entrainment by the plunging jet, as well as the number of bubbles with film radius smaller than 2 mm. This again results in decreased particle production with increasing seawater temperature.

Salter, M. E.; Nilsson, E. D.; Butcher, A.; Bilde, M.

2014-07-01

19

The mechanics of liquid jets  

Microsoft Academic Search

Conservation laws for a liquid are considered along with aspects of jet instability, jet geometry, drop size upon jet breakup, the driven jet, and the sol-gel process and other applications of liquid jets. Macroscopic conservation equations for a liquid are examined and stability analyses of cylindrical liquid jets are conducted, taking into account an inviscid and a viscous free cylindrical

J. N. Anno

1977-01-01

20

Journal of Fluid Mechanics Plunging cavities  

E-print Network

is generated on the liquid jet. The first image of the sequence presents the arrival of the bulge University Press 2011 doi:10.1017/jfm.2011.168 1 #12;Journal of Fluid Mechanics Focus luids on F 0 10 cm JetJournal of Fluid Mechanics Focus luids on F Plunging cavities C. CLANET LadHyX, UMR7646 du CNRS

Boyer, Edmond

21

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

22

Pressure fluctuations on plunge pool floors  

Microsoft Academic Search

The paper describes the pressure fluctuation field on a plunge pool floor subjected to jet impingement. The data for both mean and fluctuating components is presented for a range of velocities, plunge length, plunge pool depths, types of outlet devices, and jet diameters. The data for circular jets are compared in detail with other data available for wide rectangular nappes

D. A. Ervine; H. T. Falvey; W. Withers

1997-01-01

23

Temporal analysis of power law liquid jets  

Microsoft Academic Search

In this paper we investigate the breakup mechanisms of power law liquid jets. The viscosity of the liquid is represented the Carreau–Yasuda model, and the surface tension of the liquid jet has a variation (gradient) along the jet axial direction. The surface tension gradient may be introduced by the thermal disturbance of the jet surface as it comes of out

Zhanjun Gao; Kam Ng

2010-01-01

24

Mechanisms of the breakup of liquid jets  

Microsoft Academic Search

A general theory of the onset of breakup of liquid jets in an ambient gas is given. The theory is based on the linear stability analysis of a viscous liquid jet with respect to spatially growing disturbances. The three independent parameters in the theory are the Reynolds number R, the Weber number We, and the gas-to-liquid density ratio Q. The

S. P. Lin; Z. W. Lian

1990-01-01

25

On the instability of liquid jet and liquid curtain  

Microsoft Academic Search

The spatial instability of liquid jets and liquid curtains is investigated by using linear theory. For the case of a viscous liquid jet into an inviscid ambient gas, a unified theory is developed. It is found that the existing theories, including Rayleigh, Keller, Taylor, and Chandrasekhar's modes, are only special cases of the unified theory. Thus, this new theory would

Zhi Wen Lian

1990-01-01

26

Liquid-jet impact on liquid and solid surfaces  

Microsoft Academic Search

Experiments were conducted to investigate the mechanisms of the liquid-jet impact on liquid and solid surfaces associated with cavitation damage and rain erosion. In this work, a liquid jet of 3 mm diameter, generated using a single impact jet apparatus, was impacted at ca. 600 m s?1 on the surface of water and polymethyl-methacrylate (PMMA) placed 15 mm below the

T. Obara; N. K. Bourne; J. E. Field

1995-01-01

27

Whipping Instabilities in Electrified Liquid Jets  

Microsoft Academic Search

A liquid jet may develop different types of instabilities, like the so-called\\u000aRayleigh-Plateau instability, which breaks the jet into droplets. However,\\u000aanother type of instabilities may appear when we electrify a liquid jet and\\u000ainduce some charge at his surface. Among them, the most common is the so-called\\u000aWhipping Instability, which is characterized by violent and fast lashes of the

Alvaro G. Marin; Guillaume Riboux; Ignacio G. Loscertales; Antonio Barrero

2008-01-01

28

Velocity Discontinuity Instability of a Liquid Jet  

Microsoft Academic Search

The instability of a high-speed liquid jet with a velocity which has a transient rise followed by a linear decay with time is studied experimentally and theoretically. The jet is produced experimentally by subjecting a liquid reservoir to a shock-wave pressure. Using a shadowgraph technique, in an interval of thirty microseconds four successive quarter-microsecond exposures were taken using jets of

B. Dunne; B. Cassen

1956-01-01

29

Liquid jet pumped by rising gas bubbles  

NASA Technical Reports Server (NTRS)

A two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. Bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature.

Hussain, N. A.; Siegel, R.

1975-01-01

30

Laminar Instability of Cylindrical Liquid Jets  

Microsoft Academic Search

Interfacial instability of slightly miscible, laminar, cylindrical liquid jets in another fluid is examined. A general explicit dispersion equation is derived using an integro-differential approach. Under appropriate conditions, the resultant equation reduces to the dispersion relationships of Rayleigh, Weber, and Bogy, and matches Tomotika's equation for both limiting and non-limiting cases. The influence of jet and ambient fluid properties, mass

Ho. Teng

1994-01-01

31

Capillary Instability of Free Liquid Jets  

Microsoft Academic Search

\\u000a This chapter deals with capillary instability of straight free liquid jets moving in air. It begins with linear stability\\u000a theory for small perturbations of Newtonian liquid jets and discusses the unstable modes, characteristic growth rates, temporal\\u000a and spatial instabilities and their underlying physical mechanisms. The linear theory also provides an estimate of the main\\u000a droplet size emerging from capillary breakup.

N. Ashgriz; A. L. Yarin

32

The liquid fuel jet in subsonic crossflow  

NASA Technical Reports Server (NTRS)

An analytical/numerical model is described which predicts the behavior of nonreacting and reacting liquid jets injected transversely into subsonic cross flow. The compressible flowfield about the elliptical jet cross section is solved at various locations along the jet trajectory by analytical means for free-stream local Mach number perpendicular to jet cross section smaller than 0.3 and by numerical means for free-stream local Mach number perpendicular to jet cross section in the range 0.3-1.0. External and internal boundary layers along the jet cross section are solved by integral and numerical methods, and the mass losses due to boundary layer shedding, evaporation, and combustion are calculated and incorporated into the trajectory calculation. Comparison of predicted trajectories is made with limited experimental observations.

Nguyen, T. T.; Karagozian, A. R.

1990-01-01

33

Controlling Cold Plasma Jets Interacting with Liquids  

NASA Astrophysics Data System (ADS)

Plasmas interacting with liquids are of great interest for environmental, chemical, and biomedical applications. In this work we present optical diagnostics on atmospheric pressure plasma jets interacting with liquids. Combining the diagnostic results with numerical simulations yields an understanding of fundamental processes such as air species diffusion into the jet effluents. Especially for plasma treatment of physiological liquids in ambient air, atmospheric species play a key role. To achieve a desired reactive component output, the generation processes from these ambient air species are controlled. Plasma jets are characterized by laser induced fluorescence spectroscopy, by absorption and emission spectroscopy, and by flow simulations. With the gained knowledge we are able to tailor the reactive component composition and to influence plasma jet-liquid interaction. We show that reactive species generation within plasma treated liquid can be tuned and apply the findings to biological cells to investigate the effect of reactive oxygen and nitrogen species (RONS). The plasma treated liquids are investigated regarding their pH value, OH radicals, nitrate and nitrite, and H2O2 content. From the tailored plasma treatment a significant insight into the relevant processes in plasma acidification of liquids has been gained.

Reuter, Stephan; Hammer, Malte; Winter, Joern; Masur, Kai; von Woedtke, Thomas; Weltmann, Klaus-Dieter

2012-10-01

34

Liquid Jet Instability and Atomization in a Coaxial Gas Stream  

Microsoft Academic Search

An overview of the near and far-field breakup and atomization of a liquid jet by a high speed annular gas jet is presented. The various regimes of liquid jet breakup are discussed in the parameter space of the liquid Reynolds number, the aerodynamic Weber number, and the ratio of the momentum fluxes between the gas and the liquid streams. Recent

J. C. Lasheras; E. J. Hopfinger

2000-01-01

35

Self-Destabilizing Mechanism of Circular Liquid Jet  

Microsoft Academic Search

Disintegration mechanism through a liquid-phase feedback loop is explored for a circular liquid jet issued into an otherwise quiescent gas. An asymptotic analysis of capillary waves radiating from the liquid jet tip is used to derive analytical expression for the feed back loop for the regular axisymmetric liquid jet disintegration occurring at a large distance from the nozzle exit for

Akira Umemura

2007-01-01

36

Interaction between Supersonic Disintegrating Liquid Jets and Their Shock Waves  

Microsoft Academic Search

We used ultrafast x radiography and developed a novel multiphase numerical simulation to reveal the origin and the unique dynamics of the liquid-jet-generated shock waves and their interactions with the jets. Liquid-jet-generated shock waves are transiently correlated to the structural evolution of the disintegrating jets. The multiphase simulation revealed that the aerodynamic interaction between the liquid jet and the shock

Kyoung-Su Im; Seong-Kyun Cheong; X. Liu; Wang Jin; M.-C. Lai; Mark W. Tate; Alper Ercan; Matthew J. Renzi; Daniel R. Schuette; Sol M. Gruner

2009-01-01

37

Propagation of gas jet in liquid  

Microsoft Academic Search

A comprehensive experimental study was made of discharge of a gas jet from an orifice and its evolution in a liquid medium. Nitrogen, air, helium, chlorine, carbon dioxide, hydrogen chloride, ammonia, and water vapor superheated to 200 to 250 C were discharged vertically up, vertically down, or laterally into water at 18 to 100 C as well as into aqueous

V. A. Surin; V. N. Yevchenko; V. M. Rubin

1984-01-01

38

Study of Liquid Jet Impingement on Screens.  

National Technical Information Service (NTIS)

A model is presented for an unconfined flow, such as a free jet, impinging on a screen which incorporates the influence of liquid deflection by the screen. The boundary layer blockage coefficient is introduced. This coefficient depends on the screen weave...

F. T. Dodge, R. E. Ricker

1976-01-01

39

Liquid jet propeller integrated with reservoir, channel, and cover  

Microsoft Academic Search

This paper describes a liquid jet propeller (based on a focused ultrasonic beam) that is integrated with a reservoir, microchannel, and cover. The integration allows continuous supply of a liquid thin film (through surface tension) to the jet propeller, and we have obtained continuous propulsion of an atomized liquid jet.

Joyita Dutta; Hongyu Yu; Chuang-Yuan Lee; Eun Sok Kim

2007-01-01

40

On the mechanics of high speed liquid jets  

Microsoft Academic Search

Attention is given to the mechanics of high-speed liquid jets in terms of emergence and flight mechanics of a jet flying at speeds which are supersonic relative to the sound speed of the liquid. The question is treated experimentally via an Imacon image converter camera, and theoretically via similarity arguments and the Chaplygin transformation to evaluate liquid overcompression during jet

J. E. Field; M. B. Lesser

1977-01-01

41

Stability of a liquid jet into incompressible gases and liquids: Part 2. Effects of the irrotational  

E-print Network

Stability of a liquid jet into incompressible gases and liquids: Part 2. Effects of an irrotational, viscous pressure on the stability of a liquid jet into gases and liquids. The analysis extends stress in the normal stress balance at the interface. The liquid jet is always unsta- ble; at high Weber

Joseph, Daniel D.

42

Velocity-modulation atomization of liquid jets  

NASA Technical Reports Server (NTRS)

A novel atomizer based on high-amplitude velocity atomization has been developed. Presently, the most common methods of atomization can use only the Rayleigh instability of a liquid cylinder and the Kelvin-Helmholtz instability of a liquid sheet. Our atomizer is capable of atomizing liquid jets by the excitation and destabilization of many other higher-order modes of surface deformation. The potential benefits of this sprayer are more uniform fuel air mixtures, faster fuel-air mixing, extended flow ranges for commercial nozzles, and the reduction of nozzle plugging by producing small drops from large nozzles.

Dressler, John L.

1994-01-01

43

The Mechanics and Stability of Liquid Jets and Films  

Microsoft Academic Search

The underlying objective of this thesis is to study the process of coating by jet atomization, whose mechanism is divided into the mechanics and stability of liquid jets and the dynamics of thin films. The first step in the analysis of the mechanics of liquid jets is to examine the two-dimensional formation of non-Newtonian liquid jets. Steady-state, free-surface profiles and

Kevin Richard John Ellwood

1991-01-01

44

Plunge pools and paleoprecipitation  

Microsoft Academic Search

Sedimentary sequences in the form of ridges or terraces surrounding plunge pools at the base of waterfalls can provide records of past discharge and as a consequence an indirect measure of rainfall variations over many thousands of years. Waves generated by the waterfall deposit sands and pebbles as a beach at the perimeter of the plunge pool. As climatic conditions

Jonathan Nott; David Price

1994-01-01

45

Response of annular liquid jets to mass loading  

Microsoft Academic Search

An adaptive, block-bidiagonal finite difference method is used to study the response of annular liquid jets to the injection of mass into the volume enclosed by the annular jet. It is shown that the annular jet's response is characterized by damped oscillations in both the convergence length and the pressure of the gases enclosed by the jet, and that these

J. I. Ramos; Juan Falgueras

1991-01-01

46

Drop and Spray Formation from a Liquid Jet  

Microsoft Academic Search

A liquid jet emanating from a nozzle into an ambient gas is inherently unstable. It may break up into drops of diameters comparable to the jet diameter or into droplets of diameters several orders of magnitude smaller. The sizes of the drops formed from a liquid jet without external control are in general not uniform. The sizes as well as

S. P. Lin; R. D. Reitz

1998-01-01

47

DROP AND SPRAY FORMATION FROM A LIQUID JET  

Microsoft Academic Search

A liquid jet emanating from a nozzle into an ambient gas is inherently unstable. It may break up into drops of diameters comparable to the jet diameter or into droplets of diameters several orders of magnitude smaller. The sizes of the drops formed from a liquid jet without external control are in general not uniform. The sizes as well as

S. P. Lin; R. D. Reitz

1998-01-01

48

Bag breakup of nonturbulent liquid jets in crossflow  

Microsoft Academic Search

An experimental investigation of the bag breakup of round nonturbulent liquid jets in gaseous crossflow at room temperature and pressure is described. Pulsed photography, pulsed shadowgraphy, and high-speed imaging were used to observe the column and surface waves along the liquid jet and the formation and breakup of bags. Measurements included: wavelengths of column and surface waves, jet velocities, the

C.-L. Ng; R. Sankarakrishnan; K. A. Sallam

2008-01-01

49

Stability of a liquid jet into incompressible gases and liquids T. Funada a  

E-print Network

Stability of a liquid jet into incompressible gases and liquids T. Funada a , D.D. Joseph b,*, S July 2004 Abstract We carry out an analysis of the stability of a liquid jet into a gas or another that for all values of the relevant parameters, there are wavenumbers for which the liquid jet is temporally

Joseph, Daniel D.

50

Experiments with large diameter gravity driven impacting liquid jets  

Microsoft Academic Search

The phenomenon of a liquid jet released under gravity and falling through or impacting onto another liquid before colliding\\u000a with an obstructing solid surface has been studied experimentally under isothermal conditions. Usually the jet diameter was\\u000a sufficiently large to ensure jet coherency until collision. Direct flow visualization was used to study jets released into\\u000a water pools with no air head

G. J. Storr; M. Behnia

1999-01-01

51

Analysis of interaction phenomena between liquid jets and materials [preprint  

Microsoft Academic Search

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

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

1995-01-01

52

Dropsize correlation for cryogenic liquid-jet atomization  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1990-01-01

53

Dropsize correlation for cryogenic liquid-jet atomization  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1991-01-01

54

Shear flow control of gas jets in liquids  

Microsoft Academic Search

Passive control of shear flow is used to control the rate of mixing and stability of submerged gaseous jets in liquids. The object is to evaluate the effectiveness of recently developed shear flow control techniques for application to gaseous jets injected into liquids and ultimately to apply these techniques to gaseous oxidants injected into liquid metal fuels. These control techniques

T. R. Ogdn; L. A. Parnell; E. W. Hendricks; W. M. Schieber

1992-01-01

55

Shear flow control of gas jets in liquids  

Microsoft Academic Search

Passive control of shear flow is used to control the rate of mixing and stability of submerged gaseous jets in liquids. The object is to evaluate the effectiveness of recently developed shear flow control techniques for application to gaseous jets injected into liquids and ultimately to apply these techniques to gaseous oxidants injected into liquid metal fuels. These control techniques

T. G. Ogden; L. A. Parnell; E. W. Hendricks; W. M. Schieber

1993-01-01

56

Absolute and convective instability of a relaxational plane liquid jet  

Microsoft Academic Search

The stability of a plane relaxational liquid jet has been studied theoretically and experimentally through linear stability analysis and flow visualizations. The relaxational liquid jet is obtained by the outflow of a liquid from a plane channel with an upstream fully developed Poiseuille flow into an ambient stagnant gas. Linear spatial stability calculations show that there are five convectively unstable

L. Daniel Söderberg

2003-01-01

57

jet-compressible-gas-july25.tex 1 Liquid jet in a high Mach number air stream  

E-print Network

jet-compressible-gas-july25.tex 1 Liquid jet in a high Mach number air stream T.Funada, D, Minneapolis, MN 55455, USA Abstract The instability of circular liquid jet immersed in a coflowing high growth rate for n = 1 modes exceeds n = 0 when the viscosity of the liquid jet is large. The effects

Joseph, Daniel D.

58

Surface wave transition before breakup on a laminar liquid jet  

Microsoft Academic Search

Problems of liquid jet breakup are very fundamental in the fluid-dynamics and application fields of atomization. Instability theories of the surface wave were usually used to describe the breakup phenomena. In these theories, it was assumed that the surface wave was a regular sinusoidal wave. However, irregular surface waves were frequently observed even though a liquid jet was laminar. In

M Arai; K Amagai

1999-01-01

59

Analysis of interaction phenomena between liquid jets and materials  

Microsoft Academic Search

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

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

1995-01-01

60

Self-Destabilizing Mechanism of Circular Liquid Jet  

Microsoft Academic Search

When an issued liquid jet breaks up into droplets at a short distance from the nozzle exit, its surface deforms significantly over its whole length. The one-dimensional model developed in the first report is refined so as to describe the deformation of the liquid jet tip and it is applied to analyze strong interactions between the capillary deformation of the

Akira Umemura

2007-01-01

61

Atomization characteristics on the surface of a round liquid jet  

Microsoft Academic Search

Fundamental mechanisms of liquid jet breakup are identified and quantified. The quality of the atomization of liquids is an important parameter of many technological processes and is, e.g. for fuels and propellants critical in defining engine performance. This investigation takes a look at the jet behavior for a single injector element to determine the influence of the injection conditions on

R. Branam

2004-01-01

62

Experimental and theoretical stability investigations of plane liquid jets  

Microsoft Academic Search

The present investigation has been undertaken in order to better understand the development of free, plane liquid jets. Both the development of the basic laminar flow as well as its stability have been investigated theoretically and experimentally.The velocity field and free surface location of a liquid jet emanating from a plane channel was calculated numerically and the velocity and surface

L. D. Söderberg; P. H. Alfredsson

1998-01-01

63

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

64

Integrated numerical prediction of atomization process of liquid hydrogen jet  

NASA Astrophysics Data System (ADS)

The 3-D structure of the liquid atomization behavior of an LH jet flow through a pinhole nozzle is numerically investigated and visualized by a new type of integrated simulation technique. The present computational fluid dynamics (CFD) analysis focuses on the thermodynamic effect on the consecutive breakup of a cryogenic liquid column, the formation of a liquid film, and the generation of droplets in the outlet section of the pinhole nozzle. Utilizing the governing equations for a high-speed turbulent cryogenic jet flow through a pinhole nozzle based on the thermal nonequilibrium LES-VOF model in conjunction with the CSF model, an integrated parallel computation is performed to clarify the detailed atomization process of a high-speed LH2 jet flow through a pinhole nozzle and to acquire data, which is difficult to confirm by experiment, such as atomization length, liquid core shape, droplet-size distribution, spray angle, droplet velocity profiles, and thermal field surrounding the atomizing jet flow. According to the present computation, the cryogenic atomization rate and the LH2 droplets-gas two-phase flow characteristics are found to be controlled by the turbulence perturbation upstream of the pinhole nozzle, hydrodynamic instabilities at the gas-liquid interface and shear stress between the liquid core and the periphery of the LH2 jet. Furthermore, calculation of the effect of cryogenic atomization on the jet thermal field shows that such atomization extensively enhances the thermal diffusion surrounding the LH2 jet flow.

Ishimoto, Jun; Ohira, Katsuhide; Okabayashi, Kazuki; Chitose, Keiko

2008-05-01

65

Interaction between supersonic disintegrating liquid jets and their shock waves.  

PubMed

We used ultrafast x radiography and developed a novel multiphase numerical simulation to reveal the origin and the unique dynamics of the liquid-jet-generated shock waves and their interactions with the jets. Liquid-jet-generated shock waves are transiently correlated to the structural evolution of the disintegrating jets. The multiphase simulation revealed that the aerodynamic interaction between the liquid jet and the shock waves results in an intriguing ambient gas distribution in the vicinity of the shock front, as validated by the ultrafast x-radiography measurements. The excellent agreement between the data and the simulation suggests the combined experimental and computational approach should find broader applications in predicting and understanding dynamics of highly transient multiphase flows. PMID:19257675

Im, Kyoung-Su; Cheong, Seong-Kyun; Liu, X; Wang, Jin; Lai, Ming-Chia; Tate, Mark W; Ercan, Alper; Renzi, Matthew J; Schuette, Daniel R; Gruner, Sol M

2009-02-20

66

Interaction between Supersonic Disintegrating Liquid Jets and Their Shock Waves  

SciTech Connect

We used ultrafast x radiography and developed a novel multiphase numerical simulation to reveal the origin and the unique dynamics of the liquid-jet-generated shock waves and their interactions with the jets. Liquid-jet-generated shock waves are transiently correlated to the structural evolution of the disintegrating jets. The multiphase simulation revealed that the aerodynamic interaction between the liquid jet and the shock waves results in an intriguing ambient gas distribution in the vicinity of the shock front, as validated by the ultrafast x-radiography measurements. The excellent agreement between the data and the simulation suggests the combined experimental and computational approach should find broader applications in predicting and understanding dynamics of highly transient multiphase flows.

Im, Kyoung-Su; Cheong, Seong-Kyun; Liu, X.; Wang Jin; Lai, M.-C.; Tate, Mark W.; Ercan, Alper; Renzi, Matthew J.; Schuette, Daniel R.; Gruner, Sol M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Wayne State University, Detroit, Michigan 48202 (United States); Cornell University, Ithaca, New York 14853 (United States)

2009-02-20

67

Spray jet penetration and distribution of modulated liquid jets in subsonic cross-flows  

Microsoft Academic Search

Modulated liquid jets injected into subsonic cross-flows are empirically studied by using a mechanical liquid jet modulation\\u000a apparatus. Experimental investigations were conducted using water over a range of cross-flow velocities from 5 m\\/s to 143\\u000a m\\/s and with modulated liquid jet frequencies from 35.7 Hz to 166.2 Hz and so on. PDPA(phase Doppler particle anemometry)\\u000a was employed to measure droplet

In Chul Lee; Young Su Kang; Hee Jang Moon; Seok Pil Jang; Jin Kon Kim; Jaye Koo

2010-01-01

68

The pressure relaxation of liquid jets after isochoric heating  

Microsoft Academic Search

During isochoric heating by fast neutron irradiation, a high pressure is almost instantaneously built up inside the falling liquid jets in a HYLIFE (ICF) reactor. It has been suggested that the jets will breakup as a consequence of negative pressure occurring during the relaxation. This is important to both the subsequent condensation process and the chamber wall design. In this

X. M. Chen; V. E. Schrock

1990-01-01

69

Characterization of primary atomization mechanism of straight liquid jets  

Microsoft Academic Search

Detailed numerical simulations of straight liquid jets have been carried out to elucidate the mechanism of liquid primary atomization. The impact of liquid against the gas forms the umbrella-shaped front where initial atomization occurs subsequently. At later time, surface instability also develops on the liquid core surface, leading to ligament\\/droplet formation from the core. As the ligament\\/droplet formation mechanism has

Junji Shinjo; Akira Umemura

2010-01-01

70

Absolute and Convective Instability of a Liquid Jet  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

71

Liquid flow focused by a gas: jetting, dripping, and recirculation.  

PubMed

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. PMID:18851159

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

2008-09-01

72

Characteristics of liquid jet atomization across a high-speed airstream. III - Breakup process of liquid jet and internal structure of spray  

Microsoft Academic Search

To elucidate deformation and breakup processes of a liquid jet across an airstream, tomograms of the liquid jet were taken by means of the laser light sheet method. In this method, fluorescent dye, Eosine-Y, was contained in the injected water, and the liquid jet was illuminated by the Nd:YAG laser light sheet. There are two types of atomization mechanisms. In

Tetsuya Oda; Hiroyuki Hiroyasu; Keiya Nishida

1993-01-01

73

Cavitating Jet Method and System for Oxygenation of Liquids  

NASA Technical Reports Server (NTRS)

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

Chahine, Georges L.

2012-01-01

74

Self-Destabilizing Mechanism of Circular Liquid Jet  

Microsoft Academic Search

Capillary waves are radiated upstream from the liquid jet tip which contracts under the action of surface tension force from its upstream portion. The possible processes which change the upstream propagating capillary waves to unstable waves moving downstream with the liquid flow are explored on the basis of the one-dimensional governing equations which are derived to describe the temporal surface

Akira Umemura

2007-01-01

75

Interface Dynamics in a Plunge Tank  

Microsoft Academic Search

A fine thread plunging vertically into a bath filled with glycerin creates a cusp-like free surface profile. For Stokes flows of this type the Reynolds numbers are typically O(0.1). Photo-micrographic recordings of the meniscus distortion in the vicinity of the contact line reveal that air can be engulfed into the liquid from the interface. The air entrapment is due to

Peter Simpkins; Valerie Kuck

1998-01-01

76

Numerical modeling of the interaction of liquid drops and jets with shock waves and gas jets  

Microsoft Academic Search

The motion of a liquid drop (jet) and of the ambient gas is described, in the general case, by Navier-Stokes equations. An approximate solution to the interaction of a plane shock wave with a single liquid drop is presented. Based on the analysis, the general system of Navier-Stokes equations is reduced to two groups of equations, Euler equations for gas

V. S. Surov

1993-01-01

77

Instability of Electrically Driven Polymer Liquid Jets  

Microsoft Academic Search

Polymer nanofibers can be generated by a electrospinning process. The process involves electrically charged jet of polymer\\u000a solutions evolving from a droplet. The jet stretches in vertical direction due to the difference between charged particle\\u000a and constant current located at the collector, while the Coulomb and viscoelastic forces start to contribute to radial and\\u000a azimuthal (torsional) stretching. In this paper,

Minhyung Lee; Seung Baik Kang; Joo Hyuk Park

2006-01-01

78

Impinging jet separators for liquid metal magnetohydrodynamic power cycles  

NASA Technical Reports Server (NTRS)

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

Bogdanoff, D. W.

1973-01-01

79

Atomization of a Small Diameter Liquid Jet by a High-Speed Gas Stream  

Microsoft Academic Search

The breakup and atomization of a liquid jet by a high-speed gas stream is a multi-parameter problem. A generic case, of interest for practical applications, is that where the gas stream is coaxial with the liquid jet and the gas to liquid nozzle area ratio is of order one. Here we consider the situation where a small diameter liquid jet

C. M. Varga; E. J. Hopfinger; J. C. Lasheras

2001-01-01

80

The relaxation of liquid jet after isochoric heating  

SciTech Connect

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 jets. Therefore, the temperature and the pressure distribution within the jets during the relaxation are of great interest. The relaxation process begins as the rarefaction wave propagates inward from the jet's surface. A simplified model is constricted. According to this simplified model, the jump-off velocity amounts to an infinite outward acceleration. This situation is stable in the Taylor sense. Until the liquid fractures, the outer surface is then in a state of deceleration. This situation is Taylor unstable. The authors calculate an initial critical wavelength of 8.2 {times} 10{sup {minus}5} m. Upon fracturing, the outer surface of the annulus experiences a high acceleration, while its inner surface is decelerating and both these surfaces are Taylor stable. The present calculation provides useful insight into the possible fracture and fragmentation mode of HYLIFE jets. Compressible fluid theory will be required to obtain more accurate prediction of the flow and pressure fields. 3 refs., 1 fig.

Chen, Xiang M.; Schrock, V.E. (Univ. of California, Berkeley (USA))

1989-01-01

81

Transverse liquid fuel jet breakup, burning, and ignition  

SciTech Connect

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

Li, H.

1990-01-01

82

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

83

Modeling of Turbulence Effect on Liquid Jet Atomization  

NASA Technical Reports Server (NTRS)

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

Trinh, H. P.

2007-01-01

84

Numerical modeling for primary atomization of liquid jets  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

85

Combined aerodynamic and electrostatic atomization of dielectric liquid jets  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

86

On transit time instability in liquid jets  

NASA Technical Reports Server (NTRS)

A basic transit time instability in flows with disturbances of speed is found. It was shown that the mass distribution is established by and large by the described transit time effects. These transit time effects may also be involved for gas jets.

Grabitz, G.; Meier, G.

1982-01-01

87

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

Microsoft Academic Search

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

Yonggang Zhu; Andrea Prosperetti

2000-01-01

88

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

89

Transient liquid jet breakup model and comparison with phase doppler measurements  

Microsoft Academic Search

A new liquid jet breakup model is developed based on the transient breakup mechanism and incorporated into the KIVA-II code.\\u000a Liquid column is considered as a chain of balls. Rayleigh-Taylor instability and Kelvin-Helmholtz instability was applied\\u000a to the liquid jet column. Liquid jet column is continuously surveyed to apply breakup mechanisms. Once liquid droplets are\\u000a separated from the main liquid

Sang Ku Chang; Ja Ye Koo; Hong Chul Chung

1995-01-01

90

Initial breakup of a small-diameter liquid jet by a high-speed gas stream  

Microsoft Academic Search

The situation of a small-diameter liquid jet exposed to a large-diameter high-speed gas jet (gas-to-liquid nozzle area ratio of order 100 to 1000) is investigated experimentally. Flow visualization and particle-sizing techniques are employed to examine the initial jet breakup process and primary liquid atomization. Observations of the initial breakup of the liquid jet in the near-nozzle region, combined with droplet-size

C. M. Varga; J. C. Lasheras; E. J. Hopfinger

2003-01-01

91

Non-axisymmetric breakup of a liquid jet during atomization  

SciTech Connect

The existing aerodynamic theory is not capable of predicting the phenomenon of nonaxisymmetric breakup of a liquid jet, which has long been observed in experiments. A dispersion equation which accounts for the growth of asymmetric waves is derived in this paper. It is demonstrated that there exists a critical Weber number, below which the growth of the nonaxisymmetric disturbance becomes dominant. The present theory indicates the domination of sinuous wave and the possible formation of curling flat sheet from an axisymmetric jet. According to the present analysis, for a highspeed jet, it is the drops, instead of rings as predicted by the theory based on the axisymmetric assumption, that breakaway from the jet surface. 30 refs.

Yang, H.Q. (CFD Research Corp., Huntsville, AL (USA))

1991-01-01

92

On the mechanism of spray formation from liquid jets  

Microsoft Academic Search

A fundamental physical mechanism whereby sprays are formed from liquid jets is formulated. It is shown that a combination of axial disturbances cannot produce the necessary conditions for nonaxial evolution of drops. These conditions are satisfied by a nonaxial sequence of superimposed disturbances, propagating one on top of the other. The resulting model is used to describe the evolution of

S. Sadik; Y. Zimmels

2003-01-01

93

Stability of a liquid jet discharging into a stagnant atmosphere  

Microsoft Academic Search

The atomization of a liquid jet discharging into a stagnant air atmosphere is a familiar, natural phenomenon that, nevertheless, is not completely well understood yet. In order to deepen our understanding of the physics governing the process, we have carried out a local linear spatial stability analysis of a basic solution, which is computed self-consistently from the Navier-Stokes equations in

Miguel Pérez-Saborid; José M. Gordillo

2003-01-01

94

Modeling the disintegration of modulated liquid jets using volume-of-fluid (VOF) methodology  

Microsoft Academic Search

In this study, we present the numerical investigations on the effect of finite velocity modulations imposed on an otherwise unperturbed cylindrical liquid jet issuing into stagnant gas. Sinusoidal velocity fluctuations of finite frequency and amplitude are imposed at the liquid jet inlet and the resulting liquid jet surface deformation is captured using a volume of fluid (VOF) methodology, utilizing compressive

Vedanth Srinivasan; Abraham J. Salazar; Kozo Saito

2011-01-01

95

Primary atomization of liquid jets issuing from rocket engine coaxial injectors  

Microsoft Academic Search

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid-propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their optical opacity. This work focuses on a characteristic of the primary

Roger D. Woodward

1993-01-01

96

An Electrically Driven Impinging Liquid Jet for Direct Cooling of Heated Surfaces  

Microsoft Academic Search

An electrically driven impinging liquid jet concept is being proposed and numerically investigated for direct cooling of heated surfaces. The liquid jet flow is generated with the aid of uniquely designed electrodes immersed in a liquid bath and positioned nearby a heated surface. The jet flow is generated based on the electric conduction phenomenon. This numerical study reveals that high

Miad Yazdani; Jamal Seyed-Yagoobi

2010-01-01

97

Behavior of cylindrical liquid jets evolving in a transverse acoustic field  

Microsoft Academic Search

This paper presents a theoretical and an experimental investigation of low-velocity cylindrical liquid jets submitted to transverse planar acoustic waves. For this purpose, the behavior of a liquid jet traversing the section of a Kundt tube was examined. Experiments reported that the liquid jet could be either deviated from its trajectory or deformed as a succession of lobes oriented in

Jean-Baptiste Carpentier; Françoise Baillot; Jean-Bernard Blaisot; Christophe Dumouchel

2009-01-01

98

Mechanism of air entrainment by a disturbed liquid jet C. D. Ohl,a)  

E-print Network

Mechanism of air entrainment by a disturbed liquid jet C. D. Ohl,a) H. N. Og~uz, and A disturbances on a falling jet are a powerful agent for air entrainment at the free surface of a liquid pool of Physics. S1070-6631 00 02507-1 I. INTRODUCTION Consider a liquid jet falling into a pool of an otherwise

Ohl, Claus-Dieter

99

Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup  

NASA Technical Reports Server (NTRS)

Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. For certain flow regimes, it has been observed that the liquid jet surface is highly turbulent. This turbulence characteristic plays a key role on the breakup of the liquid jet near to the injector exit. Other experiments also showed that the breakup length of the liquid core is sharply shortened as the liquid jet is changed from the laminar to the turbulent flow conditions. In the numerical and physical modeling arena, most of commonly used atomization models do not include the turbulence effect. Limited attempts have been made in modeling the turbulence phenomena on the liquid jet disintegration. The subject correlation and models treat the turbulence either as an only source or a primary driver in the breakup process. This study aims to model the turbulence effect in the atomization process of a cylindrical liquid jet. In the course of this study, two widely used models, Reitz's primary atomization (blob) and Taylor-Analogy-Break (TAB) secondary droplet breakup by O Rourke et al. are examined. Additional terms are derived and implemented appropriately into these two models to account for the turbulence effect on the atomization process. Since this enhancement effort is based on a framework of the two existing atomization models, it is appropriate to denote the two present models as T-blob and T-TAB for the primary and secondary atomization predictions, respectively. In the primary breakup model, the level of the turbulence effect on the liquid breakup depends on the characteristic time scales and the initial flow conditions. This treatment offers a balance of contributions of individual physical phenomena on the liquid breakup process. For the secondary breakup, an addition turbulence force acted on parent drops is modeled and integrated into the TAB governing equation. The drop size formed from this breakup regime is estimated based on the energy balance before and after the breakup occurrence. The turbulence energy is also considered in this process.

Trinh, Huu; Chen, C. P.

2004-01-01

100

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

101

Study of liquid jet instability by confocal microscopy  

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

102

Simulation of liquid-jet overflow in droplet deposition processes  

SciTech Connect

Porosity formation in spray deposition processes is investigated. The emphasis is on one possible mechanism of micro-pore formation during droplet spreading and solidification: liquid-jet overflow. To this end, the Navier-Stokes equations are solved numerically using finite differences and the free surface is tracked using the Volume of Fluid (VOF) method. A previously developed multi-directional solidification algorithm is adapted and implemented in the Navier-Stokes solver to perform numerical simulations of liquid-metal droplet impact, spreading, and solidification. The results obtained allow a detailed description of the liquid-jet overflow mechanism and of the resulting solidified disk morphology. The influence of the Weber and Reynolds numbers, the solidification constant, and the contact angle are investigated.

Delplanque, J.P.; Rangel, R.H. [Univ. of California, Irvine, CA (United States)] [Univ. of California, Irvine, CA (United States)

1999-05-28

103

The effects of mass transfer, adsorption and relative motion on the break up of liquid jets in liquids  

NASA Astrophysics Data System (ADS)

The hydrodynamic stability of laminar liquid jets issuing into immiscible liquids in the presence of mass transfer an solute adsorption was investigated theoretically using linear hydrodynamic stability theory and experimentally with jets of hexamethyldisiloxane injected into water with acetone transfer between the phases and adsorption of sodium tetradecyl sulfate. The theory predicts and the experiments investigate the effects of mass transfer and solute adsorption on jet length, drop size, asymmetric disturbance amplitude and wavelength, and conditions leading to jet atomization. In addition, the theory predicts and the experiments investigate the conditions in which interfacial turbulence is present in liquid-liquid jets.

Coyle, R. W.

104

Analytical and experimental studies of impinging liquid jets  

NASA Technical Reports Server (NTRS)

Impinging injectors are a common type of injector used in liquid propellant rocket engines and are typically used in engines where both propellants are injected as a liquid, e.g., engines using LOX/hydrocarbon and storable propellant combinations. The present research program is focused on providing the requisite fundamental understanding associated with impinging jet injectors for the development of an advanced a priori combustion stability design analysis capability. To date, a systematic study of the atomization characteristics of impinging liquid jets under cold-flow conditions have been completed. Effects of orifice diameter, impingement angle, pre-impingement length, orifice length-to-diameter ratio, fabrication procedure, jet flow condition and jet velocity under steady and oscillating, and atmospheric- and high-pressure environments have been investigated. Results of these experimental studies have been compared to current models of sheet breakup and drop formation. In addition, the research findings have been scrutinized to provide a fundamental explanation for a proven empirical correlation used in the design of stable impinging injector-based rocket engines.

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

1994-01-01

105

The use of liquid jets to simulate angled drop impact  

NASA Astrophysics Data System (ADS)

The liquid jet impact technique has been used extensively for the quantitative study of rain impact. Most of this work has been for normal impact. Although some angled impact studies have been pursued using jets, these have been purely of a qualitative nature. This paper develops the theory of angled drop impact. This allows the establishment of a method of correlating between angled drop and jet impact and obtaining ``equivalent drop'' curves for jet impact. The correlation is also applied to normal impact. For normal impact it is shown that the previously published equivalent drop curves need to be modified especially at low velocities. The results for both normal and angled impact are discussed with reference to the details of the jet profile, and it is shown that angled jets may be considered as having an average equivalent drop size. The theory of angled impact also explains the shape of damage marks produced by impact and why the amount of damage decreases so rapidly with increasing angle.

Hand, R. J.; Field, J. E.; Townsend, D.

1991-12-01

106

Electric field induced sheeting and breakup of dielectric liquid jets  

NASA Astrophysics Data System (ADS)

We report experimental observations of the controlled deformation of a dielectric liquid jet subjected to a local high-voltage electrostatic field in the direction normal to the jet. The jet deforms to the shape of an elliptic cylinder upon application of a normal electrostatic field. As the applied electric field strength is increased, the elliptic cylindrical jet deforms permanently into a flat sheet, and eventually breaks-up into droplets. We interpret this observation—the stretch of the jet is in the normal direction to the applied electric field—qualitatively using the Taylor-Melcher leaky dielectric theory, and develop a simple scaling model that predicts the critical electric field strength for the jet-to-sheet transition. Our model shows a good agreement with experimental results, and has a form that is consistent with the classical drop deformation criterion in the Taylor-Melcher theory. Finally, we statistically analyze the resultant droplets from sheet breakup, and find that increasing the applied electric field strength improves droplet uniformity and reduces droplet size.

Khoshnevis, Ahmad; Tsai, Scott S. H.; Esmaeilzadeh, Esmaeil

2014-01-01

107

Analysis of liquid reservoir effect induced by pulsed laser liquid jet.  

PubMed

A pulsed-laser-induced liquid jet (LILJ) is a new device used in neurosurgery to simultaneously crush, incise, and aspirate tissues and tumors, preserving blood vessels and nerves. In addition, a feature of a pulsed LILJ is its ability to excavate tissue at constant depth while a liquid jet is being repeatedly focused at the same point. To clarify the mechanisms of constant depth of excavation, we employed a gelatin phantom and extracted brain tissue using a high-speed camera, and we then confirmed that the liquid-reservoir-induced LILJ played an important role in enabling the safe usage of an LILJ. PMID:24109838

Arafune, T; Kato, T; Kobayashi, E; Washio, T; Nakagawa, A; Ogawa, Y; Tominaga, T

2013-01-01

108

Dynamics of a liquid jet atomized by gaseous crossflow  

NASA Astrophysics Data System (ADS)

When captured by high-speed, high-resolution videos, the dynamics of a liquid jet subject to a crossflowing air stream with no external forcing appears to be composed by slow column bending motions and fast traveling surface waves. Sequences of consecutive near field line-of-sight images of the jet acquired for gas Weber numbers between 10 and 300 and momentum flux ratios between 10 and 100 are analyzed with the method of snapshots to decouple this complex liquid interface motion into few fundamental dynamic modes. The exposure time of each snapshot ``freezes'' the flow, thus providing a sharp liquid interface, while the acquisition rate is comparable to the characteristic time of moderate Weber number surface waves. Spectral decomposition analysis reveals broad-band oscillations that can be linked to the amplification of column waves near the point of column break-up. As the Weber number increases at constant momentum flux ratio, the broad band peak shifts toward higher frequencies until the aliasing limit is reached. As the liquid jet velocity increases, and the column becomes turbulent, a cascade of finer temporal and spatial structures are found with increasing pixel brightness variation intensity that affect similarly small scales of the downstream spray.

Marco, Arienti; Hagen, Gregory; Corn, May; Soteriou, Marios

2008-11-01

109

Parametric Investigation of Liquid Jets in Low Gravity  

NASA Technical Reports Server (NTRS)

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

Chato, David J.

2005-01-01

110

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

111

Liquid Engine Jet Atomization Workshop report  

NASA Technical Reports Server (NTRS)

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

Gross, Klaus W.

1987-01-01

112

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

E-print Network

LETTERS Ultrafast X-ray study of dense-liquid-jet flow dynamics using structure High-speed liquid jets and sprays are complex multiphase flow phenomena with many important industrial understanding of the breakup and atomization mechanism of the fuel jet. It has long been known that the breakup

Loss, Daniel

113

Simulation of liquid-jet overflow in droplet deposition processes  

Microsoft Academic Search

Porosity formation in spray deposition processes is investigated. The emphasis is on one possible mechanism of micro-pore formation during droplet spreading and solidification: liquid-jet overflow. To this end, the Navier–Stokes equations are solved numerically using finite differences and the free surface is tracked using the Volume of Fluid (VOF) method. A previously developed multi-directional solidification algorithm is adapted and implemented

J.-P. Delplanque; R. H. Rangel

1999-01-01

114

Unsteady air bubble entrainment and detrainment at a plunging breaker: dominant time scales and similarity of water level variations  

Microsoft Academic Search

At plunging breakers, air bubbles are entrained at the impingement of the water jet, formed at the top of the wave, with the water free surface in front. During the present study, air bubble entrainment at a pseudo-plunging breaker was investigated at near full-scale and further experimental work studied the bubble detrainment process. Experimental observations included the generation and propagation

Hubert Chanson; Shin-ichi Aoki; Mamoru Maruyama

2002-01-01

115

Liquid jets injected into non-uniform crossflow  

NASA Astrophysics Data System (ADS)

An experimental study has been conducted with liquid jets injected transversely into a crossflow to study the effect of non-uniformities in the crossflow velocity distribution to the jet behavior. Two different non-uniform crossflows were created during this work, a shear-laden crossflow and a swirling crossflow. The shear-laden crossflow was generated by merging two independent, co-directional, parallel airstreams creating a shear mixing layer at the interface between them. The crossflow exhibited a quasi-linear velocity gradient across the height of the test chamber. By varying the velocities of the two airstreams, the sense and the slope of the crossflow velocity gradient could be changed. Particle Image Velocimetry (PIV) studies were conducted to characterize the crossflow. The parameter, UR, is defined as the ratio of the velocities of the two streams and governs the velocity gradient. A positive velocity gradient was observed for UR > 1 and a negative velocity gradient for UR < 1. PIV and Phase Doppler Particle Anemometry (PDPA) studies were conducted to study the penetration and atomization of 0.5 mm diameter water jets injected into this crossflow. The crossflow velocity gradient was observed to have a significant effect on jet penetration as well as the post breakup spray. For high UR (> 1), jet penetration increased and the Sauter Mean Diameter (SMD) distribution became more uniform. For low UR (< 1), low penetration, higher droplet velocities and better atomization were observed. The second crossflow tested was a swirling flow generated using in-house designed axial swirlers. Three swirlers were used, with vane exit angles of 30°, 45° and 60°. Laser Doppler Velocimetry (LDV) was used to study the crossflow velocities. The axial (Ux) and the tangential (Utheta) components of the crossflow velocity were observed to decrease with increasing radial distance away from the centerbody. The flow angle of the crossflow was smaller than the vane exit angle, with the difference increasing with the vane exit angle. Water jets were injected from a 0.5 mm diameter orifice located on a cylindrical centerbody. Multi-plane PIV measurements were conducted to study the penetration and droplet velocity distribution of the jets. The jets were observed to follow a path close to the helical trajectory of the crossflow with a flow angle slightly less than the crossflow. This deficit in flow angle is attributed to the centrifugal acceleration experienced by the jet. Mie-Scattering images obtained from PIV were used to recreate the jet plume and to obtain the jet trajectory for penetration analysis. In cylindrical coordinate system, the jet penetration can be described in terms of radial and "circumferential" penetration, where circumferential penetration relates to the difference in the circumferential displacement of the jet and the crossflow over the same streamwise displacement. Radial penetration increased with q while circumferential penetration increased with swirl angle. PIV results from cross-sectional and streamwise planes were combined to generate three-dimensional droplet velocity distribution throughout the jet plume. The three-dimensional velocity distribution yielded further insight into the evolution of the jet plume.

Tambe, Samir

116

Jet impingement and primary atomization of non-Newtonian liquids  

NASA Astrophysics Data System (ADS)

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

Mallory, Jennifer A.

117

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

Microsoft Academic Search

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

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

1995-01-01

118

Atomization patterns of liquid sheets formed by two impinging jets  

NASA Astrophysics Data System (ADS)

High fidelity numerical simulations have been performed to study the atomization patterns and breakup characteristics of liquid sheets formed by two impinging jets. A fully three-dimensional Volume-of-Fluid method with adaptive mesh refinement (AMR) based on octree-mesh is used to simulate the primary atomization. The start of the art visualization techniques with volume rending were also used to highlight the breakup characteristics. The oblique collision of two cylindrical laminar jets leads to the liquid owing outward from the impact point, creating a thin sheet which lies in a plane perpendicular to the plane containing the two jets and disintegrates into ligaments or droplets. The breakup of the sheet is dominant by the viscosity and surface tension effects (Reynolds and Webber number). The periodic waves from the point of impingement were apparent on the surface of the sheet. The circumferentially space drops were shed from the periphery of the sheet, as well as the ligaments were fragmented from the leading edge of the sheet and then broke into droplets following the Rayleigh mechanism. The impact waves caused early breakdown of the sheet downstream of the impingement point, whereas waves amplified by aerodynamic stresses controlled the breakdown of the rest of the sheet and the ligaments.

Ma, Dong-Jun; Chen, Xiao-Dong; Yang, Vigor

2010-11-01

119

Nonlinear breakup of a coaxial liquid jet in a swirling gas stream  

Microsoft Academic Search

Nonlinear asymmetric breakup of a liquid jet exposed to a swirling gas stream is investigated by a perturbation expansion technique with the initial amplitude of the disturbance as the perturbation parameter. The effects of gas-to-liquid axial velocity ratio and gas swirl number on the liquid jet instability and breakup length have been studied. The breakup length predictions show good agreement

Ashraf A. Ibrahim; Milind A. Jog

2006-01-01

120

Dynamics of the Shock Waves Generated by High-Speed Liquid Jets  

Microsoft Academic Search

Ultra fast x-radiography and a multiphase numerical simulation were used to reveal complete dynamical characteristics of the shock waves generated by supersonic liquid jets. Unlike the conventional shock waves by a rigid body compression, this shock waves generated by highly transient liquid jets are characterized by an immediately expansion after short compression caused by the liquid deformation due to aerodynamic

Kyoung-Su Im; Seong-Kyun Cheong; Jin Wang; Ming-Chia Lai

2007-01-01

121

Analysis Of Plunging Phenomena In Water Reservoirs  

Microsoft Academic Search

Two analyses of plunging phenomena in reservoirs are presented, one based upon a simple energy conserving flow and the other upon a gradually varied two-layer system. The various types of interfacial profiles are described and the depth at the plunge point is determined. The predicted plunge depth agrees reasonably well with the laboratory measurements of SINGH and SHAH (1971).

S. B. Savage; J. Brimberg

1975-01-01

122

Nanoscale Liquid Jets Shape New Line of Business  

NASA Technical Reports Server (NTRS)

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

2003-01-01

123

A numerical study on the breakup process of laminar liquid jets into a gas  

Microsoft Academic Search

Surface phenomena of liquid jets into still air are numerically investigated. The liquid and air are treated as a single continuum with dynamically evolving interfaces captured by the level-set method. The jets considered are laminar: the jet exit Reynolds number ranges from 480 to 2300, with the Weber number of 3.1-28 000. The liquid\\/air density ratios are about 103. In

Yu Pan; Kazuhiko Suga

2006-01-01

124

The fluid motion physics: The interaction mechanics of a free liquid jet with a body and with the other free liquid jet  

E-print Network

Solution of a problem on the interaction mechanics of a free liquid jet with a flat plate, body and with other jet has been achieved by means of a graphic-analytical method, developed by author of the given article. This method has allowed physically adequately and visually to describe the flow field near the streamlined surface and to give expressions for quantitative evaluation of the jet pressure profile onto this surface. This method is equally correct for both a flat jet and a jet with a round cross-section. Analysis of the flow field has allowed to detect a jet component, induced by the body fore part in the unrestricted fluid stream and determining the body form drag. Besides that, it has been ascertained that a friction also induces the jet component in the potential boundary layer. It has been introduced a new notion of the stream total head vector, determining an origin of the possible jet flow in the stream.

Arsenjev, S L

2008-01-01

125

Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

126

Capillary instability of axisymmetric, active liquid crystal jets.  

PubMed

We study linear stability of an infinitely long, axisymmetric, cylindrical active liquid crystal (ALC) jet in a passive isotropic fluid matrix using a polar active liquid crystal (ALC) model. We identify three possible unstable modes (or mechanisms) as the result of the interaction between the flow and the active (or self-propelled) molecular motion. The first unstable mode is related to the polarity vector instability when coupled to the flow field in the presence of the molecular activity. It can be traced back to the inherent polarity vector instability in a bulk active liquid crystal flow. However, it can be grossly amplified in the ALC jet to encompass up to infinitely many unstable growth rates when the long range distortional elastic interaction is weak in certain parameter regimes; it can also be suppressed in other parameter regimes completely. The second unstable mode is related to the classical capillary or Rayleigh instability, which exists in a finite wave interval [0, k(cutoff)]. The new feature for this instability lies in the dependence of the cutoff wave number (k(cutoff)) on the activity of the active matter system. For ALC jets with sufficiently strong contractile activity, the instability can be completely suppressed though. The third unstable mode is due to the active viscous stress. This unstable mode can emerge in the intermediate wave number regime at a sufficiently strong active viscosity and even expand all the way to the zero wave number limit when the Rayleigh unstable mode is absent. It can also be suppressed in the regime of weak active viscous stress. At any given values of the model parameters, the three types of instabilities can show up either individually or in a certain combination, or be completely suppressed altogether. In this paper, we discuss the positive growth rates associated with the instabilities, windows of instability and their dependence on model parameters through extensive numerical computations aided by asymptotic analyses. PMID:25074458

Yang, Xiaogang; Wang, Qi

2014-09-21

127

Stability of a Liquid Jet into Incompressible Gases and Liquids: Part 2. Eects of the irrotational viscous pressure  

Microsoft Academic Search

In this paper we investigate the eects of an irrotational, viscous pressure on the stability of a liquid jet into gases and liquids. The analysis extends our earlier work (part 1) in which the stability of the viscous jet was studied assuming that the motion and pressure are irrotational and the viscosity enters through the jump in the viscous normal

T. Funada; M. Saitoh; J. Wangy; D. D. Josephyz

128

A study of liquid jets formed by bubble collapse under shock waves in elastic and Newtonian liquids 1 Dedicated to the memory of Professor Gianni Astarita 1  

Microsoft Academic Search

This paper describes a study of the formation of liquid jets in elastic and Newtonian liquids. The technique used to study this phenomenon involves a shock wave, emanating from the collapse of a cavitation bubble, which causes a gas bubble underneath the free surface of a liquid column to collapse, thereby producing a liquid jet. A comparison of the jets

P. R Williams; P. M Williams; S. W. J Brown

1998-01-01

129

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

130

The fluid motion physics: The interaction mechanics of a free liquid jet with a body and with the other free liquid jet  

Microsoft Academic Search

Solution of a problem on the interaction mechanics of a free liquid jet with a flat plate, body and with other jet has been achieved by means of a graphic-analytical method, developed by author of the given article. This method has allowed physically adequately and visually to describe the flow field near the streamlined surface and to give expressions for

S. L. Arsenjev

2008-01-01

131

Interface Dynamics in a Plunge Tank  

NASA Astrophysics Data System (ADS)

A fine thread plunging vertically into a bath filled with glycerin creates a cusp-like free surface profile. For Stokes flows of this type the Reynolds numbers are typically O(0.1). Photo-micrographic recordings of the meniscus distortion in the vicinity of the contact line reveal that air can be engulfed into the liquid from the interface. The air entrapment is due to tip-streaming from an extended filament that originates at the apex of the cusp. This behavior occurs when the capillary number, Ca, exceeds a critical value. Bubbles recirculating in the bath tend to coagulate and gravitate toward the moving thread. Eventually the larger bubbles generated in this way can themselves become sufficiently distorted by the shear that smaller ones are once again created by tip-streaming. Measurements of the surface distortion as a function of Ca and the bubble size distribution will be discussed.

Simpkins, Peter; Kuck, Valerie

1998-11-01

132

Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection  

E-print Network

Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline ion inertial fusion reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive protection A. Konkachbaev 1, N.B. Morley, M.A. Abdou Mechanical and Aerospace Engineering Department, UCLA 43

Abdou, Mohamed

133

The Impact of Density Ratio on the Primary Atomization of a Turbulent Liquid Jet in Crossflow  

Microsoft Academic Search

Atomizing liquids by injecting them into crossflows is a common approach to generate fuel sprays in gas turbines and augmentors. Although correlations derived from experimental data exist for the jet penetration, predicting the drop size distribution resulting from the primary breakup of the liquid jet is a more challenging task. Furthermore, most correlations are derived from experimental data performed at

Marcus Herrmann

2009-01-01

134

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

Microsoft Academic Search

Scope and method of study. An experimental and computational research is performed to study the deformation and breakup of round nonturbulent liquid jets in uniform gaseous crossflow. Pulsed photography and shadow graphy in conjunction with high-speed imaging were used to study the wave phenomena and the droplets properties\\/transport dynamics of a nonturbulent liquid jet injected into a uniform crossflow within

Chee-Loon Ng

2006-01-01

135

Instability of a liquid jet emerging from a droplet upon collision with a solid surface  

E-print Network

Instability of a liquid jet emerging from a droplet upon collision with a solid surface H.-Y. Kim perturbation theory is developed to investigate the interface instabilities of a radially-expanding, liquid jet,a) Z. C. Feng,b) and J.-H. Chun Department of Mechanical Engineering, Massachusetts Institute

Kim, Ho-Young

136

Microcutting of living tissue slices and stem cell colonies by using mechanical tool and liquid jet  

Microsoft Academic Search

There is a growing need for methods to cut living tissues in vitro and cell cultures in microscale in biological and medical research. This paper presents two different microrobotic methods for cutting: mechanical microdissection using a sharp needle and liquid jet cutting utilizing a pressured liquid jet. Test devices for both the methods were built and the experiments were conducted

Juha Hirvonen; Pekka Ronkanen; Timo Ylikomi; M. Blauer; R. Suuronen; H. Skottman; P. Kallio

2008-01-01

137

The effect of air swirl profile on the instability of a viscous liquid jet  

Microsoft Academic Search

A temporal linear stability analysis has been carried out to predict the instability of a viscous liquid jet surrounded by a swirling air stream with three-dimensional disturbances. The effects of flow conditions and fluid properties on the instability of the liquid jet are investigated via a parametric study by varying axial Weber number axial velocity ratio of the gas to

Y. Liao; S. M. Jeng; M. A. Jog; M. A. Benjamin

2000-01-01

138

Detailed Numerical Simulations of the Primary Atomization of a Turbulent Liquid Jet in Crossflow  

Microsoft Academic Search

Atomizing liquids by injecting them into crossflows is a common approach to generate fuel sprays in gas turbines and augmentors. While correlations derived from experimental data exist for the jet penetration, predicting the drop size distribution resulting from the primary breakup of the liquid jet is a more challenging task. This is in part due to the fact that often,

Marcus Herrmann

2008-01-01

139

Analysis of strong acoustic excitation on the breakup and dispersion of a liquid jet  

Microsoft Academic Search

The effect of strong acoustic waves on the breakup and dispersion of cylindrical liquid jets is considered with regard to combustion instabilities of liquid injection burners. An experimental study showed that a strong acoustic excitation modifies jet stability at low injection velocities (by reduction of the breakup length). This phenomenon, which exhibits saturation and threshold effects, is especially sensitive to

Bernard Labegorre

1993-01-01

140

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

141

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

142

Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline protection  

E-print Network

Effect of initial turbulence intensity and velocity profile on liquid jets for IFE beamline reactors utilize banks of liquid jets and vortex flow tubes to protect sensitive beam line components from protection A. Konkachbaev, N.B. Morley and M. A. Abdou Mechanical and Aerospace Engineering Department, UCLA

California at Los Angeles, University of

143

Isothermal mass transfer in annular liquid jets with Sievert’ solubility law  

Microsoft Academic Search

Summary A study of isothermal gas absorption by underpressurized, axisymmetric, thin, inviscid, incompressible, annular liquid jets which form enclosed volumes, where hazardous wastes may be burned, is presented. The study considers the nonlinear dynamical coupling between the fluid dynamics of, and the gases enclosed by, the annular liquid jet. It assumes equilibrium conditions at the interfaces, and employs Sievert’ solubility

J. I. Ramos

1995-01-01

144

Isothermal mass transfer in annular liquid jets with Sievert's solubility law  

Microsoft Academic Search

A study of isothermal gas absorption by underpressurized, axisymmetric, thin, inviscid, incompressible, annular liquid jets which form enclosed volumes, where hazardous wastes may be burned, is presented. The study considers the nonlinear dynamical coupling between the fluid dynamics of, and the gases enclosed by, the annular liquid jet. It assumes equilibrium conditions at the interfaces, and employs Sievert's solubility law

J. I. Ramos

1995-01-01

145

An experimental investigation on the interaction of hydraulic jumps formed by two normal impinging circular liquid jets  

Microsoft Academic Search

The flow field due to two normal impinging liquid jets is different from the flow field associated with a single normal impinging liquid jet, and even from the flow field around two normal impinging compressible fluid jets. Depending on the spacing between the two jets and their relative strengths, different kinds of hydraulic jump interactions are possible, resulting in a

R. P. Kate; P. K. Das; Suman Chakraborty

2007-01-01

146

Liquid flow-focused by a gas: jetting, dripping and recirculation  

E-print Network

Flow-focused liquid jetting by gas is explored by (a) experiment and (b) direct axisymmetric VOF numerical simulation. The cone-jet flow pattern is seen to evolve as we modify the liquid flow-rate around the jetting-dripping transition. As observed in other focused flows like 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 incipient 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, showing remarkable agreement with experiments.

Herrada, Miguel A; Ojeda-Monge, Antonio; Bluth, Benjamin; Riesco-Chueca, Pascual

2008-01-01

147

Analysis of impingement heat transfer for two parallel liquid-metal slot jets  

NASA Technical Reports Server (NTRS)

An analytical method is developed for determining heat transfer by impinging liquid-metal slot jets. The method involves mapping the jet flow region, which is bounded by free streamlines, into a potential plane where it becomes a uniform flow in a channel of constant width. The energy equation is transformed into potential plane coordinates and is solved in the channel flow region. Conformal mapping is then used to transform the solution back into the physical plane and obtain the desired heat-transfer characteristics. The analysis given here determines the heat-transfer characteristics for two parallel liquid-metal slot jets impinging normally against a uniformly heated flat plate. The liquid-metal assumptions are made that the jets are inviscid and that molecular conduction is dominating heat diffusion. Wall temperature distributions along the heated plate are obtained as a function of spacing between the jets and the jet Peclet number.

Siegel, R.

1974-01-01

148

Termination of Plasma Discharge by High-Z Liquid Impurity Jet Injection in a Tokamak Reactor  

SciTech Connect

A feasibility study is presented of fast tokamak plasma terminations by means of high-Z impurity liquid jet injections in order to reduce the technological requirements of such terminations. The calculation was carried out by combining models described for the jet ablation and the current termination and taking into account the ionization of the jet material exposed to generated runaway electrons. The liquid jet was assumed to fragment and thus to deposit more massive impurity ions in the plasma. Although argon or krypton jet injection generates the runaway electron current, it decays in several hundred milliseconds with ionization of the residual jet material. These high-Z impurity jet injections would also be applicable for terminating or reducing the runaway electron current tails generated by major plasma disruptions.

Itoh, Yasuyuki [Toshiba Corporation (Japan); Murakami, Yoshiki [Toshiba Corporation (Japan); Nishio, Satoshi [Japan Atomic Energy Research Institute (Japan)

2001-09-15

149

Instability of a charged non-Newtonian liquid jet.  

PubMed

A three-dimensional instability analysis of an electrified non-Newtonian liquid jet is performed in this paper so as to understand the competition between viscoelastic stresses, electric force, and surface tension. The analysis employs the leaky-dielectric model to account for the charge transport process and the Oldroyd-B model to take the viscoelastic effect into account. Results show that the viscoelastic stresses play a stabilizing role while electrification destabilizes the disturbances with shorter wavelength and higher azimuthal wave numbers. However, the viscoelastic stabilizing effect is not so significant on the sinuous mode (with azimuthal wave number m = 1) compared with the other modes, which thus promotes sinuous disturbances. This result is consistent with the presence of bending motion in most experimental observations. PMID:22400657

Ruo, An-Cheng; Chen, Kuan-Hung; Chang, Min-Hsing; Chen, Falin

2012-01-01

150

Distinctive Flow Properties of Liquid-Jet Generated by EHD Pump and Conical Nozzle  

Microsoft Academic Search

The electrohydrodynamical (EHD) liquid-jets induced by the mechanism in which is referred to as pure conduction pumping were investigated in isothermal weakly conducting liquids, HFC43-10 and HCFC123. The properties of liquid-jet (flow velocity, pumping pressure and flow pattern) were examined by using a grounded electrode with four different types against a pseudo-doughnut electrode under an applied dc voltage. These electrode

Ryoichi Hanaoka; Hiroyuki Nakamichi; Shinzo Takata; Tadashi Fukami

2004-01-01

151

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

NASA Technical Reports Server (NTRS)

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

Symons, E. P.

1976-01-01

152

Atomization of liquids in a Pease-Anthony Venturi scrubber. Part I. Jet dynamics.  

PubMed

Jet dynamics, in particular jet penetration, is an important design parameter affecting the collection efficiency of Venturi scrubbers. A mathematical description of the trajectory, break-up and penetration of liquid jets initially transversal to a subsonic gas stream is presented. Experimental data obtained from a laboratory scale Venturi scrubber, operated with liquid injected into the throat through a single orifice, jet velocities between 6.07 and 15.9 m/s, and throat gas velocities between 58.3 and 74.9 m/s, is presented and used to validate the model. PMID:12573843

Gonçalves, J A S; Costa, M A M; Henrique, P R; Coury, J R

2003-02-28

153

Direct Numerical Simulations of Plunging Airfoils Yves Allaneau  

E-print Network

Direct Numerical Simulations of Plunging Airfoils Yves Allaneau and Antony Jameson Stanford plunging airfoils using a low dissipation finite volume scheme that preserves kinetic energy. The kinetic Reynolds numbers plunging airfoils. Results are discussed and compared with experimental data. Nomenclature

Jameson, Antony

154

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

PubMed

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

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

2014-05-21

155

Experimental investigation of liquid jet injection into Mach 6 hypersonic crossflow  

NASA Astrophysics Data System (ADS)

The injection of a liquid jet into a crossing Mach 6 air flow is investigated. Experiments were conducted on a sharp leading edge flat plate with flush mounted injectors. Water jets were introduced through different nozzle shapes at relevant jet-to-air momentum-flux ratios. Sufficient temporal resolution to capture small scale effects was obtained by high-speed recording, while directional illumination allowed variation in field of view. Shock pattern and flow topology were visualized by Schlieren-technique. Correlations are proposed on relating water jet penetration height and lateral extension with the injection ratio and orifice diameter for circular injector jets. Penetration height and lateral extension are compared for different injector shapes at relevant jet-to-air momentum-flux ratios showing that penetration height and lateral extension decrease and increase, respectively, with injector’s aspect ratio. Probability density function analysis has shown that the mixing of the jet with the crossflow is completed at a distance of x/ d j ~ 40, independent of the momentum-flux ratio. Mean velocity profiles related with the liquid jet have been extracted by means of an ensemble correlation PIV algorithm. Finally, frequency analyses of the jet breakup and fluctuating shock pattern are performed using a Fast Fourier algorithm and characteristic Strouhal numbers of St = 0.18 for the liquid jet breakup and of St = 0.011 for the separation shock fluctuation are obtained.

Beloki Perurena, J.; Asma, C. O.; Theunissen, R.; Chazot, O.

2009-03-01

156

An experimental investigation into liquid jetting modes and break-up mechanisms conducted in a new reduced gravity facility  

Microsoft Academic Search

Liquid jets, important to many industrial applications including various drop-on-demand processes, are experimentally produced\\u000a in reduced gravity conditions and analysed to determine the mode the liquid jet is operating in. Three physically different\\u000a modes of liquid jetting are observed along with their associated break up mechanisms and discussed. Additionally, a) the theoretical\\u000a transition between jetting and the onset of chaotic

Barnaby P. Osborne; Theodore A. Steinberg

2006-01-01

157

Experimental investigations of steady and dynamic behavior of transverse liquid jets  

Microsoft Academic Search

The injection of a liquid jet into a crossflow of air provides a means of higher penetration and rapidly mixing liquid fuel and air for combustion applications. The structure of the spray, formed is investigated. To attain this goal, the problem is divided into the following tasks which involve: (1) characterize the penetration, breakup, atomization, mixing, and breakup of liquid

Omar M. Elshamy

2007-01-01

158

Experimental study of acoustic-hydraulic interactions on a liquid jet  

Microsoft Academic Search

Acoustic effects on the hydraulics of injection streams may be a significant feedback mechanism for combustion oscillations in liquid propellant combustion systems. In this study, the surface waves on a liquid jet were studied using a laser technique. The natural frequency of the waves was measured as a function of the liquid velocity for two orifice sizes. An intense transverse

James A. Chalmers; Frederick H. Reardon

1991-01-01

159

The fluid motion physics: The interaction mechanics of a free liquid jet with a body and with the other free liquid jet  

Microsoft Academic Search

Solution of a problem on the interaction mechanics of a free liquid jet with\\u000aa flat plate, body and with other jet has been achieved by means of a\\u000agraphic-analytical method, developed by author of the given article. This\\u000amethod has allowed physically adequately and visually to describe the flow\\u000afield near the streamlined surface and to give expressions for

S. L. Arsenjev

2008-01-01

160

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.

161

The relative efficiency of cryogens used for plunge-cooling biological specimens.  

PubMed

Coolants used for freezing biological specimens were tested for cooling performance in the continuous plunge mode. Results from bare thermocouples showed that ethane cooled faster than propane or a propane:pentane mixture, even when warmed to 25 K above its freezing point. Propane coolants were more efficient than Freon 22 and the slowest cooling occurred in boiling liquid nitrogen. Hydrated gelatin specimens showed similar results with ethane cooling about 33% faster than propane. Epoxy resin specimens cooled faster than hydrated gelatin specimens of similar size. Hydrated and resin specimens cooled over increasing distances as plunge velocity increased. A bare thermocouple, however, cooled over a constant distance when plunged above a critical velocity. This phenomenon may reflect vapour formation and its suppression at high plunge velocities. The rate of cooling in hydrated specimens is shown to have an absolute limit and cannot be modelled by bare thermocouples or resin specimens. PMID:3553603

Ryan, K P; Purse, D H; Robinson, S G; Wood, J W

1987-01-01

162

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

Microsoft Academic Search

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

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

2008-01-01

163

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

164

Transverse Wave Motion on a Thin Capillary Jet of a Viscous Liquid  

Microsoft Academic Search

An analysis for the transverse wave patterns observed on jets of viscous Newtonian liquids upon ejection from sinusoidally, transversely vibrating capillary nozzles into air is presented. Propagation is controlled by fluid density and surface tension, and is affected by viscosity. The analysis is a linearized one, which ignores internal motion of the jet fluid, but accounts satisfactorily for viscous dissipation.

S. Middleman; J. Gavis

1965-01-01

165

Investigation on mechanism of critical cavitating flow in liquid jet pumps under operating limits  

Microsoft Academic Search

The critical cavitating flow in liquid jet pumps under operating limits is investigated in this paper. Measurements on the axial pressure distribution along the wall of jet pumps indicate that two-phase critical flow occurs in the throat pipe under operating limits. The entrained flow rate and the distribution of the wall pressure upstream lowest pressure section does not change when

X. Long; H. Yao; J. Zhao

2009-01-01

166

Experimental study of the atomization process for viscous liquids by meniscus perturbation and micro air jet  

E-print Network

An experimental study was performed to understand the atomization process in the specialized printing method which consists of the high frequency oscillating motion of a needle and a micro air jet. Highly viscous liquids, ...

Lee, Heejin, 1976-

2004-01-01

167

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

E-print Network

The fluid mechanics of the deposition of micron liquid (olive oil) droplets on a glass wall in an impinging turbulent air jet is studied experimentally. The spatial patterns of droplets deposited on a wall are measured by ...

Liu, Tianshu

168

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

Microsoft Academic Search

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

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

169

Modeling of liquid ceramic precursor droplets in a high velocity oxy-fuel flame jet  

Microsoft Academic Search

Production of coatings by high velocity oxy-fuel (HVOF) flame jet processing of liquid precursor droplets can be an attractive alternative method to plasma processing. This article concerns modeling of the thermophysical processes in liquid ceramic precursor droplets injected into an HVOF flame jet. The model consists of several sub-models that include aerodynamic droplet break-up, heat and mass transfer within individual

Saptarshi Basu; Baki M. Cetegen

2008-01-01

170

Atomization of a small-diameter liquid jet by a high-speed gas stream  

Microsoft Academic Search

The situation of a small-diameter liquid jet exposed to a large-diameter high-speed gas jet is investigated experimentally. Flow visualization and particle-sizing techniques are employed to examine both the initial breakup process and subsequent secondary atomization of the liquid. It is shown that nearly all of the breakup takes place in the near-field and that the bulk of the atomization is

Christopher Michael Varga

2002-01-01

171

Numerical simulation of the disintegration of forced liquid jets using volume-of-fluid method  

Microsoft Academic Search

The present numerical study investigates the effect of finite sinusoidal velocity modulations imposed on an otherwise unperturbed cylindrical liquid jet issuing into stagnant gas using Volume-of-Fluid (VOF) methodology. Variation of the simulation parameters, comprising of the mean liquid jet velocity, modulation amplitude and frequency grouped together using a set of non-dimensional parameters, leads to the formation of a wide gamut

Vedanth Srinivasan; Abraham J. Salazar; Kozo Saito

2010-01-01

172

Cryogenic liquid-jet breakup in two-fluid atomizers  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1991-01-01

173

On the spatial stability of a liquid jet in the presence of vapor cavities  

SciTech Connect

A dispersion equation describing the effect of temperature differences on the stability of three-dimensional cylindrical liquid jets in the presence of vapor cavities is presented by the use of linear stability analysis. The mathematical model and its solving method are verified by comparing them with the data in the literature, and then the effect of temperature differences between jet and surrounding gas on the spatial stability of liquid jet is investigated. Some conclusions can be drawn from the results of this investigation: (1) the temperature difference destabilizes the liquid jet when the jet liquid is cooler than the surrounding gas, (2) the smallest atomized droplet without taking into account the effect of temperature differences is significantly larger than that when the effect of temperature differences is taken into account, (3) the effect of temperature differences on the stability of liquid jet has little relationship with azimuthal wave modes, (4) cavitation destabilizes the liquid jet when the value of the bubble volume fraction is not greater than 0.1 (0 ? ? ? 0.1), and the temperature difference can weaken this effect of cavitation on the stability of liquid jet, and (5) cavitation is responsible for generating smaller droplets, the effect of cavitation on the critical wave number with and without taking into account the effect of temperature differences is quite different, and temperature difference is likely to fully restrain the effect of cavitation on the critical wave number; however, cavitation is again responsible for generating smaller droplets despite the effect of temperature differences when the bubble volume fraction ? = 0.1. These findings may explain some observations of practical atomizer performance.

Lü, Ming; Ning, Zhi, E-mail: zhining@bjtu.edu.cn; Lu, Mei; Yan, Kai; Fu, Juan; Sun, Chunhua [College of Mechanical and Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)] [College of Mechanical and Electrical Engineering, Beijing Jiaotong University, Beijing 100044 (China)

2013-11-15

174

Analysis of liquid-metal-jet impingement cooling in a corner region and for a row of jets  

NASA Technical Reports Server (NTRS)

A conformal mapping method was used to analyze liquid-metal-jet impingement heat transfer. The jet flow region and energy equation are transformed to correspond to uniform flow in a parallel plate channel with nonuniform heat addition along a portion of one wall. The exact solution for the wall-temperature distribution was obtained in the transformed channel, and the results are mapped back into the physical plane. Two geometries are analyzed. One is for a single slot jet directed either into an interior corner formed by two flat plates, or over the external sides of the corner; the flat plates are uniformly heated, and the corner can have various included angles. The heat-transfer coefficient at the stagnation point at the apex of the plates is obtained as a function of the corner angle, and temperature distributions are calculated along the heated walls. The second geometry is an infinite row of uniformly spaced parallel slot jets impinging normally against a uniformly heated plate. The heat-transfer behavior is obtained as a function of the spacing between the jets. Results are given for several jet Peclet numbers from 5 to 50.

Siegel, R.

1975-01-01

175

Free-Surface Shear Layer Instabilities on a High-Speed Liquid Jet  

SciTech Connect

The instabilities of the shear layer beneath the free surface of high-speed liquid jets are investigated. Such instabilities will generate waves on liquid-metal jet targets, affecting adversely the target performance. The most unstable wave number and the spatial growth rate of perturbation are predicted with linear stability theories and are shown to agree fairly well with experimental data for water jets. The effects of fluid surface tension and streamline curvature on the instabilities are analyzed to evaluate the applicability of water data to liquid-metal curved jets. It is shown that the surface tension effects are negligible when the Weber number based on the shear layer thickness is greater than six, and also the streamline curvature effects are negligible when the radius of curvature is more than 30 times greater than the shear layer thickness.

Itoh, Kazuhiro [Nagoya University (Japan); Tsuji, Yoshiyuki [Nagoya University (Japan); Nakamura, Hideo [Japan Atomic Energy Research Institute (Japan); Kukita, Yutaka [Nagoya University (Japan)

2000-01-15

176

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

NASA Astrophysics Data System (ADS)

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

Ng, Chee-Loon

177

Hydraulic jumps with corners due to obliquely inclined circular liquid jets.  

PubMed

We have discovered that hydraulic jumps corresponding to obliquely inclined circular liquid jets, under certain conditions of impingement, confer a series of interesting flow patterns (including jumps with corners). These patterns are markedly different from the regular elliptical (or oblate) shaped jump profiles that are commonly observed with higher angles of jet inclination. These patterns are attributed to the changes in the spreading flow profile due to "jet-jump interaction" at relatively lower jet inclination angles. The irregular shaped jump profiles, close to the critical angle of jet inclination, are mathematically characterized by introducing the concept of an equivalent jump radius. These theoretical predictions match excellently with the experimental findings. A phenomenological explanation is also provided by drawing analogies from shock-wave interactions in compressible fluid mechanics and from twin-jet interaction mechanisms. PMID:17677167

Kate, R P; Das, P K; Chakraborty, Suman

2007-05-01

178

Red Giant Plunging Through Space  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2006-01-01

179

Asymmetric impact of a jet with an ideal noncompressible liquid  

Microsoft Academic Search

The problem of impact of a jet belongs among classical problems. The question of asymmetric impact of a jet is of special importance in view of the development of new methods for treating metals by means of explosive energy and, in the first instance, welding by explosion [1, 2].

Yu. A. Trishin

1986-01-01

180

Numerical simulation of a liquid jet in a cross-flow using Refined Level Set Grid method  

Microsoft Academic Search

Numerical simulations are conducted to investigate the breakup mechanism of a liquid jet injected into a turbulent cross-flow using an unstructured grid LES solver. A Refined Level Set Grid (RLSG) method coupled to a Lagrangian spray model is used to capture the whole breakup process of the liquid jet. In the near field of liquid injection where the primary breakup

Dokyun Kim; Marcus Herrmann

2005-01-01

181

Comparisons between experiment and numerical simulation using a free surface technique of free-falling liquid jets  

Microsoft Academic Search

Gravity driven jets of liquid have been studied experimentally as part of investigations into the mechanisms important to breakup of liquid jets when they impact onto a liquid pool, fall through the pool and collide with the pool base. In this paper, computer simulations of the experiments using the volume of fluid (VOF) numerical technique are reported. Very good results

G. J. Storr; M. Behnia

2000-01-01

182

Interaction between Supersonic Disintegrating Liquid Jets and Their Shock Waves Kyoung-Su Im,* Seong-Kyun Cheong, X. Liu, and Jin Wang  

E-print Network

Interaction between Supersonic Disintegrating Liquid Jets and Their Shock Waves Kyoung-Su Im-generated shock waves and their interactions with the jets. Liquid-jet-generated shock waves are transiently that the aerodynamic interaction between the liquid jet and the shock waves results in an intriguing ambient gas

Gruner, Sol M.

183

Surface tension reduction of liquid by applied electric field using vibrating jet method  

Microsoft Academic Search

It has been discussed in previous papers that the surface tension of some liquids decreases during voltage application, and that this could be the main mechanism for dispersion of the liquid. However, no experimental results have been reported except for a few papers. In the present study, the vibrating jet method was employed because this is a method to measure

Masayuki Sato; Naoya Kudo; N. Saito

1998-01-01

184

Surface tension reduction of liquid by applied electric field using vibrating jet method  

Microsoft Academic Search

It has been discussed in previous papers that the surface tension of some liquids decreases during voltage application, and that this could be the main mechanism for dispersion of the liquid. However, no experimental results have been reported except for a few papers. In the present study, the vibrating jet method was employed because this is the only method available

M. Sato; N. Kudo; M. Saito

1996-01-01

185

Liquid jets, accelerated thrombolysis: a study for revascularization of cerebral embolism.  

PubMed

A prior study has reported that a rapid recanalization therapy of cerebral embolism, using liquid jet impacts generated by the interaction of gas bubbles with shock waves, can potentially penetrate through thrombi in as little as a few microseconds with very efficient ablation (Kodama et al. 1997). The present study was undertaken to examine the liquid jet impact effect on fibrinolysis in a tube model of an internal carotid artery. First, the conditions for generating the maximum penetration depth of liquid jets in the tube were investigated. Gelatin was used to mimic thrombi. The shock wave was generated by detonating a silver azide pellet weighing about a few micrograms located in a balloon catheter. The collapse of the inserted gas bubbles and the subsequent liquid jet formation were recorded with high-speed photography. Second, thrombi were formed using fresh human blood from healthy volunteers. The fibrinolysis induced by the liquid jet impact with urokinase was explored. This was conducted under selected conditions based on the experiment using the gelatin. Fibrinolysis was calculated as the percentage of the weight loss of the thrombus. Fibrinolysis with urokinase alone and with a single liquid jet impact with urokinase was 1.9 +/- 3.7% (n = 16) and 20.0 +/- 9.0% (n = 35), respectively, for an incubation time of 60 min. Statistical differences were obtained between all groups (ANOVA). These results suggest that liquid jet impact thrombolysis has the potential to be a rapid and effective therapeutic modality in recanalization therapy for patients with cerebral embolism and other clinical conditions of intra-arterial thrombosis. PMID:10461727

Kodama, T; Tatsuno, M; Sugimoto, S; Uenohara, H; Yoshimoto, T; Takayama, K

1999-07-01

186

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

NASA Astrophysics Data System (ADS)

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

Kourmatzis, A.; Shrimpton, J. S.

2014-03-01

187

Experimental investigation on structures and velocity of liquid jets in a supersonic crossflow  

NASA Astrophysics Data System (ADS)

Particle image velocimetry was applied in the study focusing on the structure and velocity of water jets injected into a Ma = 2.1 crossflow. The instantaneous structures of the jet, including surface waves in the near-injector region and vortices in the far-field, were visualized clearly. Spray velocity increases rapidly to 66% of the mainstream velocity in the region of x/d < 15, owing to the strong gas-liquid interaction near the orifice. By contrast, the velocity grows slowly in the far-field region, where the liquid inside the spray is accelerated mainly by the continuous driven force provided by the mainstream with the gas-liquid shear. The injection and atomization of liquid jet in a supersonic crossflow serves as a foundation of scramjet combustion process, by affecting the combustion efficiency and some other performances. With various forces acting on the liquid jet (Mashayek et al. [AIAA J. 46, 2674-2686 (2008)] and Wang et al. [AIAA J. 50, 1360-1366 (2012)]), the atomization process involves very complex flow physics. These physical processes include strong vortical structures, small-scale wave formation, stripping of small droplets from the jet surface, formations of ligaments, and droplets with a wide range of sizes.

Wang, Zhen-guo; Wu, Liyin; Li, Qinglian; Li, Chun

2014-09-01

188

Unsteady penetration of a target by a liquid jet.  

PubMed

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

Uth, Tobias; Deshpande, Vikram S

2013-12-10

189

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

NASA Technical Reports Server (NTRS)

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

Antoine, A. C.

1977-01-01

190

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

NASA Technical Reports Server (NTRS)

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

Labus, T. L.

1976-01-01

191

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

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1988-01-01

192

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

NASA Technical Reports Server (NTRS)

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

Lin, S. P.

2001-01-01

193

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

NASA Technical Reports Server (NTRS)

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.

1982-01-01

194

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

Microsoft Academic Search

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 mum diameter liquid-gallium-jet anode to produce an ~10 mum 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

M. Otendal; T. Tuohimaa; U. Vogt; H. M. Hertz

2008-01-01

195

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

SciTech Connect

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 ?10{sup 12} 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.; Rutishauser, S.; Stampanoni, M. [Paul Scherrer Institute, Villigen PSI (Switzerland) [Paul Scherrer Institute, Villigen PSI (Switzerland); Institute for Biomedical Engineering, Swiss Federal Institute of Technology, Zurich (Switzerland); Zhou, T.; Lundström, U.; Burvall, A.; Hertz, H. M. [Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Albanova, SE-10691 Stockholm (Sweden)] [Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Albanova, SE-10691 Stockholm (Sweden); David, C. [Paul Scherrer Institute, Villigen PSI (Switzerland)] [Paul Scherrer Institute, Villigen PSI (Switzerland)

2013-08-26

196

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

197

Plunge location of sediment driven hyperpycnal river discharges considering bottom friction, lateral entrainment, and particle settling  

NASA Astrophysics Data System (ADS)

River discharges with very high sediment loads have the potential to develop into plunging hyperpycnal flows that transition from a river jet to a turbidity current at some location basinward of the river mouth due to the density difference between the turbid river and the receiving water body. However, even if the bulk density of the turbid river is greater than that of the receiving lake or ocean, some distance is needed for the forward inertia of the river to dissipate so that the downward gravitational pull can cause the system to collapse into a subaqueous turbidity current. This collapsing at the plunge point has been found to occur when the densimetric Froude number decreases to a value between 0.3 < Frd < 0.7 (Fang and Stefan 2000, Parker and Toniolo 2007, Dai and Garcia 2010, Lamb et al. 2010). In 2D channel flow analysis at the plunge point, this has led to the concept of a two-fold criterion for plunging. The first is simply for the need of high enough suspended sediment concentration to overcome the density difference between the river fluid and the fluid of the receiving water. The second is the need for sufficiently deep water to reduce the densimetric Froude below the critical value for plunging, which leads to dependence of plunging on the receiving water basin topography (Lamb et al. 2010). In this analysis, we expand on past work by solving a system of ODE river jet equations to account for bottom friction, lateral entrainment of ambient fluid, and particle settling between the river mouth and the plunge location. Typical entrainment and bottom friction coefficients are used and the model is tested against the laboratory density current data of Fang and Stefan (1991). A suite of conditions is solved with variable river discharge velocity, aspect ratio, suspended sediment concentration, and particle size; a range of salinity values and bottom slopes are used for the receiving water body. The plunge location is then expressed as a function of the boundary conditions at the river mouth and those of the receiving water. The relationships can be used for modern systems, but can also help to put reasonable bounds on paleo-hydraulic setting. References Dai, A. & Garcia, M. H. (2010). Energy Dissipative Plunging Flows. Journal of Hydraulic Engineering, 136(8), 519-523. Fang, X. & Stefan, H. G. (1991). Integral Jet Model for Flow from an Open Channel into a Shallow Lake or Reservoir. St. Anthony Falls Hydraulic Laboratory. Fang, X. & Stefan, H. G. (2000). Dependence of dilution of a plunging discharge over a sloping bottom on inflow conditions and bottom friction. Journal of Hydraulic Research, 38(1), 15-25. Lamb, M. P., McElroy, B., Kopriva, B., Shaw, J., & Mohrig, D. (2010). Linking river-flood dynamics to hyperpycnal-plume deposits: Experiments, theory, and geological implications. Geological Society of America Bulletin, 122(9/10), 1389-1400. Parker, G. & Toniolo, H. (2007). Note on the Analysis of Plunging of Density Flows. Journal of Hydraulic Engineering, 133(6), 690-694.

Strom, K. B.; Bhattacharya, J.

2012-12-01

198

The Impact of a Deep-Water Plunging Breaker  

E-print Network

The impact of a plunging breaking wave (wavelength approximately 1.3m) on a rigidly mounted rigid cube structure (dimension 0.31m) that is partially submerged is explored through experiments and numerical calculations. The experiments are carried out in a wave tank and the breaker is generated with a mechanical wave maker using a dispersive focusing technique. The water-surface profile upstream of the front face of the cube and in its vertical centerplane is measured using a cinematic laser-induced fluorescence technique. The three-dimensional flow in the wave tank is simulated directly using the Numerical Flow Analysis (NFA) code. The experiments and the calculations are used to explore the details of the wave-impact process and, in particular, the formation of the high-speed vertical jet that is found on the front face of the cube under some impact conditions.

Ikeda, Christine; Brucker, Kyle A; Drazen, David A; Dommermuth, Douglas G; Fu, Thomas; Fullerton, Anne M; Duncan, James H

2014-01-01

199

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

200

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

201

Surface instability and primary atomization characteristics of straight liquid jet sprays  

Microsoft Academic Search

Using the detailed numerical simulation data of primary atomization, the liquid surface instability development that leads to atomization is characterized. The numerical results are compared with a theoretical analysis of liquid–gas layer for a parameter range close to high-speed Diesel jet fuel injection. For intermittent and short-duration Diesel injection, the aerodynamic surface interaction and transient head formation play an important

J. Shinjo; A. Umemura

2011-01-01

202

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

SciTech Connect

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 and interfaces, and the high density of the jet near the nozzle exit. Focused-X-ray-beam absorption measurements could provide only average quantitative density distributions using repeated imaging. Here, we report a novel approach on the basis of ultrafast synchrotron-X-ray full-field phase-contrast imaging. As illustrated in our case study, this technique reveals, for the first time, instantaneous velocity and internal structure of optically dense sprays with a combined unprecedented spatial and time resolution. This technique has tremendous potential for the study of transient phenomenon dynamics.

Wang, Y.; Im, K.; Lee, W.; Wang, J.; Fezzaa, K.; Hung, D.; Winkelman, J.; X-Ray Science Division; Mayo Clinic; Visteon Corp.

2008-04-01

203

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

204

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

PubMed

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 × 10(9) photons?(s × mm(2) × mrad(2) × 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. PMID:22225218

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

2011-12-01

205

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

206

Mathematical modeling of plunging reservoir flows  

Microsoft Academic Search

Flow into and through a reservoir with a sloping bottom is modeled in two dimensions. The inflow is denser than the reservoir water and plunges below the surface to form a density current. The unsteady momentum and continuity equations are formulated in cylindrical coordinates. The standard k-? turbulence model is used with an extension to include production or destruction of

Gerard J. Farrell; Heinz G. Stefan

1988-01-01

207

Recurrent plunging ranula treated with OK432  

Microsoft Academic Search

A 36-year-old man was admitted who had a 2-month history of swelling of the right submandibular area and the right side of the mouth floor. He had undergone operations for right plunging ranula with a lesion on the floor of the mouth twice 7 years ago. Under fluoroscopic guidance, the contents of the cyst were aspirated as much as possible

Jeong-Su Woo; Soon Hwang; Heung-Man Lee

2003-01-01

208

Gravitational Radiation from Plunging Orbits - Perturbative Study -  

E-print Network

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 quasi-normal 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 quasi-normal 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.

Yasushi Mino; Jeandrew Brink

2008-09-16

209

Micromachined jets for liquid impingement cooling of VLSI chips  

Microsoft Academic Search

Two-phase microjet impingement cooling is a potential solution for removing heat from high-power VLSI chips. Arrays of microjets promise to achieve more uniform chip temperatures and very high heat transfer coefficients. This paper presents the design and fabrication of single-jets and multijet arrays with circular orifice diameters ranging from 40 to 76 ?m, as well as integrated heater and temperature

Evelyn N. Wang; Lian Zhang; Linan Jiang; Jae-Mo Koo; James G. Maveety; Eduardo A. Sanchez; Kenneth E. Goodson; Thomas W. Kenny

2004-01-01

210

A two-phase model for subcooled and superheated liquid jets  

SciTech Connect

This paper describes a two-phase jet model for predicting the liquid rainout (capture) and composition of subcooled and superheated HF/additive pressurized liquid releases. The parent droplets of the release mixture constitute the fist phase. The second phase can in general be a vapor-liquid fog. The drops are not in equilibrium with the fog phase with which they exchange mass and energy. The fog at any location is assumed to be in local equilibrium. Correlations are developed for predicting the initial drop size for hydrodynamic breakup of jets. Applications are discussed in this paper for HF/additive mixtures. The fog phase calculations account for HF oligomerization and HF-water complex formation in the vapor phase and equilibrium between the liquid and vapor in the fog. The model incorporates jet trajectory calculations and hence can predict the amount of liquid rained out (liquid capture) and the capture distance. The HF captures predicted by the model for various release conditions are in agreement with small and large scale release experiments.

Muralidhar, R.; Jersey, G.R.; Krambeck, F.J. [Mobil Research and Development Corp., Paulsboro, NJ (United States); Sundaresan, S. [Princeton Univ., NJ (United States). Dept. of Chemical Engineering

1995-12-31

211

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

212

Dynamic Behavior in the Angular Distribution of Emission from a Micrometer-Sized Asymmetric Liquid Jet  

Microsoft Academic Search

The dynamic behavior in the angular distribution of emission was measured from an asymmetrically distorted liquid jet which was induced by laterally flowing gas. We observed that the intensity pattern was restricted to around phi˜90°,above 2% of the distortion parameter eta. The fine structure of the intensity pattern was also restricted to phi˜90°, which is evidence of the directional emission

Hee-Jong Moon; Sang-Bum Lee; Kwang-Hoon Ko; Guang-Hoon Kim; Jai-Hyung Lee; Joon-Sung Chang; Jonghoon Yi; Jongmin Lee

1998-01-01

213

Deformation of a liquid surface due to an impinging gas jet: A conformal mapping approach  

E-print Network

Deformation of a liquid surface due to an impinging gas jet: A conformal mapping approach Andong He the method of conformal mapping. The strength of our method lies in its general application to analytically to convert it to steel known as the basic oxygen conversion process1 . In the arc welding process, a high

214

Studies of transverse liquid fuel jets in high-speed air streams  

Microsoft Academic Search

This report is in two parts describing two related studies of liquid fuel jet injection. The first study was concerned with the flowfield in the immediate vicinity of the injection port for the case of a hot, supersonic main air stream. Water, kerosene, and carbon disulphide were studied as the injectants. The second study dealt with the details of penetration

J. A. Schetz; W. McVey; A. Padhye; F. Munteanu

1976-01-01

215

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

Microsoft Academic Search

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

David Lukas; Arindam Sarkar; Pavel Pokorny

2008-01-01

216

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

PubMed

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 3.0 +/- 0.6 MPa (n = 7) and 12.7 +/- 0.4 MPa (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. PMID:9434293

Kodama, T; Takayama, K; Uenohara, H

1997-12-01

217

Detailed Numerical Simulations of the Primary Atomization of a Turbulent Liquid Jet  

Microsoft Academic Search

The atomization process of turbulent liquid jets is as of this day not well understood. Detailed numerical simulations can help study the fundamental mechanisms in regions, where experimental access and analysis is virtually impossible. However, simulating atomization accurately is a huge numerical challenge since time and length scales vary over several orders of magnitude, the phase interface is a material

Marcus Herrmann

2007-01-01

218

Instabilities of charged liquid jet of polymer solution and electrospinning of Nanofibers  

Microsoft Academic Search

An experimental study of the mechanism of beads formation during electro-spinning of nanofibers is presented. Liquid jets of a polymer solution (Poly Ethylene Oxide (PEO)) were electrospun and the resulting PEO nanofibers were deposited on a grounded substrate. The collected nanofibers exhibited bead-like structures depending on: the polymer concentration in the electro spun solution, the applied voltage, the injection pressure

Khaled Sallam; Anu Osta; Abdel-Rahman El-Leathy

2007-01-01

219

Electrohydrodynamic instability of a charged liquid jet in the presence of an axial magnetic field  

Microsoft Academic Search

Electrified liquid jets subjected to electrical destabilizing mechanisms often deform asymmetrically, creating an uncontrollable random motion that prevents the formation of uniform drops or organized microstructures. Employing a magnetic field is a potentially effective method of inhibiting the onset of unstable motion. This paper develops a theoretical model to investigate the effect of an axial magnetic field on the instability

An-Cheng Ruo; Min-Hsing Chang; Falin Chen

2010-01-01

220

Self-destabilizing mechanism of a laminar inviscid liquid jet issuing from a circular nozzle  

Microsoft Academic Search

A laminar inviscid liquid (typically water) jet issuing from a circular nozzle into otherwise quiescent air disintegrates into droplets periodically at a distance from the nozzle. The Plateau-Rayleigh instability theory and others cannot determine this breakup length because they do not have any logic that determines the initial amplitude of the unstable wave responsible for the breakup. In this paper,

Akira Umemura

2011-01-01

221

The penetration of a soft solid by a liquid jet, with application to the administration of a needle-free injection  

Microsoft Academic Search

Liquid jet injections have been performed on human skin in vivo and silicone rubber using Intraject needle-free injectors. The discharge characteristics of the liquid jet were measured using a custom-built test instrument. The experiments reveal that a high- speed liquid jet penetrates a soft solid by the formation and opening of a planar crack. The fluid stagnation pressure required for

Oliver A. Shergold; Norman A. Fleck; Toby S. King

222

Liquid jet impingement cooling with diamond substrates for extremely high heat flux applications  

SciTech Connect

The combination of impinging jets and diamond substrates may provide an effective solution to a class of extremely high heat flux problems in which very localized heat loads must be removed. Some potential applications include the cooling of high-heat-load components in synchrotron x-ray, fusion, and semiconductor laser systems. Impinging liquid jets are a very effective vehicle for removing high heat fluxes. The liquid supply arrangement is relatively simple, and low thermal resistances can be routinely achieved. A jet`s cooling ability is a strong function of the size of the cooled area relative to the jet diameter. For relatively large area targets, the critical heat fluxes can approach 20 W/mm{sup 2}. In this situation, burnout usually originates at the outer edge of the cooled region as increasing heat flux inhibits the liquid supply. Limitations from liquid supply are minimized when heating is restricted to the jet stagnation zone. The high stagnation pressure and high velocity gradients appear to suppress critical flux phenomena, and fluxes of up to 400 W/mm{sup 2} have been reached without evidence of burnout. Instead, the restrictions on heat flux are closely related to properties of the cooled target. Target properties become an issue owing to the large temperatures and large temperature gradients that accompany heat fluxes over 100 W/mm{sup 2}. These conditions necessitate a target with both high thermal conductivity to prevent excessive temperatures and good mechanical properties to prevent mechanical failures. Recent developments in synthetic diamond technology present a possible solution to some of the solid-side constraints on heat flux. Polycrystalline diamond foils can now be produced by chemical vapor deposition in reasonable quantity and at reasonable cost. Synthetic single crystal diamonds as large as 1 cm{sup 2} are also available.

Lienhard, J.H. V [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Mechanical Engineering; Khounsary, A.M. [Argonne National Lab., IL (United States)

1993-09-01

223

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

224

Aerodynamic effects in the break-up of liquid jets: on the first wind-induced break-up regime  

Microsoft Academic Search

We present both numerical and analytical results from a spatial stability analysis of the coupled gas liquid hydrodynamic equations governing the first wind-induced (FWI) liquid-jet break-up regime. Our study shows that an accurate evaluation of the growth rate of instabilities developing in a liquid jet discharging into a still gaseous atmosphere requires gas viscosity to be included in the stability

J. M. Gordillo; M. Pérez-Saborid

2005-01-01

225

Subgrid analysis of liquid jet atomization J. Chesnel a,  

E-print Network

, is simulated thanks to the coupling of both level-set and VOF formulations. To avoid the apparition Liquid/gas interface curvature µ Local dynamic viscosity ls Level-set function vof Volume Of Fluid (VOF

Paris-Sud XI, Université de

226

Breakup characteristics of power-law liquid sheets formed by two impinging jets  

NASA Astrophysics Data System (ADS)

The breakup characteristics of the shear-thinning power-law liquid sheets formed by two impinging jets have been investigated with the shadowgraph technique. This paper focuses on the effects of spray parameters (jet velocity), physical parameters (viscosity) and geometry parameters (impinging angle and nozzle cross-sectional shape) on the breakup behaviors of liquid sheets. The breakup mode, sheet length and expansion angle of the sheet are extracted from the spray images obtained by a high speed camera. Impinging angle and Weber number play the similar roles in promoting the breakup of liquid sheets. With the increase of jet velocity, five different breakup modes are observed and the expansion angle increases consistently after the closed-rim mode while the sheet length first increases and then decreases. But there exists a concave consisting of a fierce drop and a second rising process on the sheet length curve for the fluid with smaller viscosity. Different nozzle cross-sectional shapes emphasize significant effects on the sheet length and expansion angle of liquid sheets. At a fixed Weber number, the liquid sheet with greater viscosity has a greater sheet length and a smaller expansion angle due to the damping effect of viscosity.

Bai, Fuqiang; Diao, Hai; Zhang, Mengzheng; Chang, Qing; Wang, Endong; Du, Qing

2014-10-01

227

Heat transfer from a liquid bath due to an impinging gas jet: A numerical study  

SciTech Connect

An impinging gasjet on a liquid surface is found in many industrial processes such as electric arc furnace steel-making and welding. Fundamental understanding of the interaction of a gas or plasmajet impinging on a liquid pool can provide important insights into process behavior resulting in improved efficiency. A numerical model is developed for solving both the impinging gas jet and the liquid pool temperature and flow fields along with the deformed interface shape for the above processing operation. Using curvilinear coordinates, the Navier-Stokes equations of each phase are solved separately and then coupled via continuity of static pressure, shear stress, temperature and heat flux at the interface.

Qian, F.; Farouk, B.; Mutharasan, R. [Drexel Univ., Philadelphia, PA (United States)

1995-12-31

228

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

E-print Network

we report an ultrafast synchrotron x-ray phase contrast imaging study of the primary breakup mechanism of a coaxial air-assisted water jet. We demonstrate that there exist great similarities in the phenomenology of primary breakup with that of the secondary breakup. Especially, a membrane-mediated breakup mechanism dominates the breakup process for a wide range of air speeds. This finding reveals the intrinsic connections of these two breakup regimes and has deep implications on the unified theoretical approach in treating the breakup mechanism of high speed liquid jet.

Wang, Y J; Fezzaa, K

2007-01-01

229

Boiling-up of liquid nitrogen jet in water  

NASA Astrophysics Data System (ADS)

The hydrodynamic processes occurring at injection of cryogenic liquid into water pool were studied experimentally. Processes accompanying the phase transitions were registered. Data testify the developing pressure burst with an amplitude sufficient for possible formation of gas hydrates when methane is injected as a cryogenic fluid.

Nakoryakov, V. E.; Tsoi, A. N.; Mezentsev, I. V.; Meleshkin, A. V.

2014-06-01

230

Thermo-capillary convection in a flowing liquid jet  

Microsoft Academic Search

In a liquid column thermocapillary convection arises under the action of an axial temperature gradient. The influence of a constant axial velocity of the column and its rotation about the longitudinal axis has been investigated. The effect of changing aspect ratio, Prandtl number and thermal expansion coefficient has also been determined. They exhibit a drastic motion of the vortex rings

Helmut F. Bauer; Werner Eidel

1997-01-01

231

Self-Destabilizing Mechanism of Circular Liquid Jet  

Microsoft Academic Search

Concluding this series of theoretical studies, a persistent self-excitation mechanism of most unstable capillary wave at the nozzle exit is proposed on the basis of the one-dimensional model developed in the first report. It is found that, once an unstable wave travels down from the nozzle exit, the most unstable Rayleigh wave is repeatedly developed for the newly issued liquid

Akira Umemura

2008-01-01

232

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

233

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

SciTech Connect

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

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

2008-06-09

234

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

NASA Technical Reports Server (NTRS)

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

235

Experimental investigation of the thermal-hydraulics of gas jet expansion In a two-dimensional liquid pool  

E-print Network

Gas jet blowdown in a two-dimensional liquid pool has been experimentally investigated. Two sets of experiments were performed: a set of hydrodynamic experiments, where a non-condensible gas is injected into a subcooled ...

Rothrock, Ray Alan

1978-01-01

236

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

237

Capillary and acceleration wave breakup of liquid jets in axial-flow airstreams  

NASA Technical Reports Server (NTRS)

Empirical correlations of reciprocal mean drop diameter with airstream momentum were derived from capillary and acceleration wave breakup of liquid jets atomized by cross stream injection into axial flow airstreams. A scanning radiometer was used to obtain data over an airstream momentum range of 3.7 to 25.7 g/sq cm sec. Transition from capillary to acceleration wave breakup was obtained at a critical Weber-Reynolds number of 1,000,000.

Ingebo, R. D.

1981-01-01

238

Domain-adaptive finite difference methods for collapsing annular liquid jets  

Microsoft Academic Search

A domain-adaptive technique which maps a time-dependent, curvilinear geometry into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets. A method of lines is used to solve the one-dimensional fluid dynamics equations written in weak conservation-law form, and upwind differences are employed to evaluate the axial convective fluxes. The

J. I. Ramos

1993-01-01

239

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

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1987-01-01

240

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

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1987-01-01

241

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

242

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

243

Plunge waveforms from inspiralling binary black holes  

E-print Network

We study the coalescence of non-spinning binary black holes from near the innermost stable circular orbit down to the final single rotating black hole. We use a technique that combines the full numerical approach to solve Einstein equations, applied in the truly non-linear regime, and linearized perturbation theory around the final distorted single black hole at later times. We compute the plunge waveforms which present a non negligible signal lasting for $t\\sim 100M$ showing early non-linear ringing, and we obtain estimates for the total gravitational energy and angular momentum radiated.

J. Baker; B. Bruegmann; M. Campanelli; C. O. Lousto; R. Takahashi

2001-02-09

244

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

PubMed

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

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

2014-01-01

245

Topological Singularities and Transitions in Two Dimensional Liquid-Liquid Jets with Surface Tension  

Microsoft Academic Search

In previous work, it was found that for small enough surface tensions, an interface that separates two immiscible, inviscid, density-matched fluids in a two dimensional shear flow, rolls up into a spiral whose innermost turns self-intersect at a finite time. This topological or pinching singularity occurs through the formation of an intense localized jet, produced by the surface tension, that

John Lowengrub; Michael Shelley

1996-01-01

246

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

SciTech Connect

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

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

2006-07-01

247

High Resolution Spectroscopy and Dynamics: from Jet Cooled Radicals to Gas-Liquid Interfaces  

NASA Astrophysics Data System (ADS)

This talk will attempt to reflect recent work in our group involving two quite different but complementary applications of high resolution molecular spectroscopy for detailed study of intramolecular as well as intermolecular dynamics in small molecules. The first is based on direct infrared absorption spectroscopy in a 100 KHz slit supersonic discharge, which provides a remarkably versatile and yet highly sensitive probe for study of important chemical transients such as open shell combustion species and molecular ions under jet cooled (10-20K), sub-Doppler conditions. For this talk will focus on gas phase spectroscopic results for a series of unsaturated hydrocarbon radical species (ethynyl, vinyl, and phenyl) reputed to be critical intermediates in soot formation. Secondly, we will discuss recent applications of high resolution IR and velocity map imaging spectroscopy toward quantum state resolved collision dynamics of jet cooled molecules from gas-room temperature ionic liquid (RTIL) and gas-self assembled monolayer (SAM) interfaces. Time permitting, we will also present new results on hyperthermal scattering of jet cooled NO radical from liquid Ga, which offer a novel window into non-adiabatic energy transfer and electron-hole pair dynamics at the gas-molten metal interface.

Sharp-Williams, E.; Roberts, M. A.; Roscioli, J. R.; Gisler, A. W.; Ziemkiewicz, M.; Nesbitt, D. J.; Dong, F.; Perkins, B. G., Jr.

2010-06-01

248

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

249

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

NASA Astrophysics Data System (ADS)

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

James, Mark D.

250

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

Microsoft Academic Search

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

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

2006-01-01

251

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

NASA Technical Reports Server (NTRS)

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

Antoine, A. C.

1977-01-01

252

Direct simulation for the instability and breakup of laminar liquid jets  

NASA Technical Reports Server (NTRS)

A direct numerical simulation method is described for predicting the deformation of laminar liquid jets. In the present nonlinear direct simulation, the convective term, which has been discarded in past linear analyses by Rayleigh and others, is included in the hydrodynamic equations. It is shown that only by maintaining full complexity of the nonlinear surface tension term accurate drop formation can be predicted. The continuity and momentum equations in the transient form are integrated on an adaptive grid, conforming the jet and surface wave shape. The equations, which are parabolic in time and elliptic in space, are solved by a TVD scheme with characteristic flux splitting. The results of the present work are discussed and compared with available measurements and other analyses. The comparison shows that among the predictions, the current 1-D direct simulation results agree best with the experimental data. Furthermore, the computer time requirements are much (an order of magnitude) smaller than those of previously reported multidimensional analyses.

Chuech, S. G.; Przekwas, A. J.; Yang, H. Q.; Gross, K. W.

1990-01-01

253

Liquid-metal-jet x-ray tube technology and tomography applications  

NASA Astrophysics Data System (ADS)

The power and brightness of electron-impact micro-focus X-ray sources have long been limited by thermal damage in the anode. Here we describe a novel X-ray microfocus source based on a new anode concept, the liquid-metal-jet anode (MetalJet). The regenerative nature of this anode allows for significantly higher e-beam power density than on conventional anodes, resulting in this source generating significantly higher brightness than other X-ray tubes in the microfocus regime (~5-50 ?m). We describe the fundamental properties of the technology and will review the current status specifically in terms of spot size, stability, lifetime, flux, acceleration voltage and brightness.

Espes, Emil; Andersson, Tommy; Björnsson, Fredrik; Gratorp, Christina; Hansson, Björn A. M.; Hemberg, Oscar; Johansson, Göran; Kronstedt, Johan; Otendal, Mikael; Tuohimaa, Tomi; Takman, Per

2014-09-01

254

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

PubMed

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

Portaro, Rocco; Ng, Hoi Dick

2013-01-01

255

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

SciTech Connect

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

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

2011-11-15

256

The penetration of a soft solid by a liquid jet, with application to the administration of a needle-free injection  

Microsoft Academic Search

Liquid jet injections have been performed on human skin in vivo and silicone rubber using Intraject needle-free injectors. The discharge characteristics of the liquid jet were measured using a custom-built test instrument. The experiments reveal that a high-speed liquid jet penetrates a soft solid by the formation and opening of a planar crack. The fluid stagnation pressure required for skin

Oliver A. Shergold; Norman A. Fleck; Toby S. King

2006-01-01

257

Effect of surface tension on a liquid-jet produced by the collapse of a laser-induced bubble against a rigid boundary  

Microsoft Academic Search

The effect of surface tension on the behavior of a liquid-jet is investigated experimentally by means of a fiber-coupled optical beam deflection (OBD) technique. It is found that a target under water is impacted in turn by a laser-plasma ablation force and by a high-speed liquid-jet impulse induced by bubble collapse in the vicinity of a rigid boundary. The liquid-jet

Xiu Mei Liu; Jie He; Jian Lu; Xiao Wu Ni

2009-01-01

258

Photoelectron spectroscopy of liquid water, some alcohols, and pure nonane in free micro jets  

NASA Astrophysics Data System (ADS)

The recently developed technique of accessing volatile liquids in a high vacuum environment by using a very thin liquid jet is implemented to carry out the first measurements of photoelectron spectra of pure liquid water, methanol, ethanol, 1-propanol, 1-butanol, and benzyl alcohol as well as of liquid n-nonane. The apparatus, which consists of a commercial hemispherical (10 cm mean radius) electron analyzer and a hollow cathode discharge He I light source is described in detail and the problems of the sampling of the photoelectrons in such an environment are discussed. For water and most of the alcohols up to six different electronic bands could be resolved. The spectra of 1-butanol and n-nonane show two weakly discernable peaks from which the threshold ionization potential could be determined. A deconvolution of the photoelectron spectra is used to extract ionization potentials of individual molecular bands of molecules near the surface of the liquid and shifts of the order of 1 eV compared to the gas phase are observed. A molecular orientation for water molecules at the surface of liquid water is inferred from a comparison of the relative band strengths with the gas phase. Similar effects are also observed for some of the alcohols. The results are discussed in terms of a simple "Born-solvation" model.

Faubel, Manfred; Steiner, Björn; Toennies, J. Peter

1997-06-01

259

Trapping of magnetic flux by the plunge region of a black hole accretion disk  

E-print Network

The existence of the radius of marginal stability means that accretion flows around black holes invariably undergo a transition from a MHD turbulent disk-like flow to an inward plunging flow. We argue that the plunging inflow can greatly enhance the trapping of large scale magnetic field on the black hole, and therefore may increase the importance of the Blandford-Znajek (BZ) effect relative to previous estimates that ignore the plunge region. We support this hypothesis by constructing and analyzing a toy-model of the dragging and trapping of a large scale field by a black hole disk, revealing a strong dependence of this effect on the effective magnetic Prandtl number of the MHD turbulent disk. Furthermore, we show that the enhancement of the BZ effect depends on the geometric thickness of the accretion disk. This may be, at least in part, the physical underpinnings of the empirical relation between the inferred geometric thickness of a black hole disk and the presence of a radio jet.

Christopher S. Reynolds; David Garofalo; Mitchell C. Begelman

2006-07-17

260

Experimental Investigation of Jet Impingement Heat Transfer Using Thermochromic Liquid Crystals  

NASA Technical Reports Server (NTRS)

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

Dempsey, Brian Paul

1997-01-01

261

Airfoil Thickness Effects on the Thrust Generation of Plunging Airfoils  

E-print Network

Airfoil Thickness Effects on the Thrust Generation of Plunging Airfoils Meilin Yu, Z. J. Wang to investigate the effects of airfoil thickness on the thrust generation of plunging airfoils and to assess the contributions of pressure and viscous forces in flapping propulsion. A series of NACA symmetric airfoils

Hu, Hui

262

Optimization of Unstalled Pitching and Plunging Motion of an Airfoil  

E-print Network

Optimization of Unstalled Pitching and Plunging Motion of an Airfoil Shuchi Yang , Shijun Luo 119260 The motion parameters of a sinusoidally pitching and plunging NACA 0012 airfoil in a uniform on the understanding and prediction of the flapping airfoil aerodynamics. It is still not clearly known how

Liu, Feng

263

The plunge reaction of the backswimmer Notonecta glauca  

Microsoft Academic Search

A reaction that causes flying backswimmers to dive into the water is described. This ‘plunge reaction’ consists of the following sequence of movements: the animal briefly (typically for 60 ms) raises the body axis head-up, then tilts downward while spreading out the rowing legs and closing the wings. The backswimmers also exhibit the plunge reaction in the laboratory when they

Rudolf Schwind

1984-01-01

264

Gas-phase flowrate effect on disintegrating cryogenic liquid-jets  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1989-01-01

265

An experimental study of the liquid film on a vertical wire under the action of an impinging annular jet  

Microsoft Academic Search

The liquid film remaining on a wire withdrawn from a liquid bath and forced through an annular jet is experimentally investigated\\u000a on a dedicated facility. An optical laser-based technique recently introduced to study liquid-film instabilities on small-radius\\u000a cylinders allows the measurement of the mean final thickness and wave characteristics. Experimental results are compared to\\u000a analytical predictions obtained with a simple

Simone Zuccher

2009-01-01

266

Free Liquid Jet Impingement from a Slot Nozzle to a Curved Plate  

Microsoft Academic Search

This article explores the heat transfer characteristics of a free liquid jet discharging from a slot nozzle and impinging vertically on a curved cylindrical shaped plate of finite thickness. Computations were done for Re = 500–1800, ? = 0.75–3, Ri\\/dn = 4.16–16.66, b\\/dn = 0.08–1.5, and dn = 0.3–2.4 mm. Results are presented for dimensionless solid–fluid interface temperature, dimensionless maximum temperature in the solid, and local and average Nusselt numbers. The

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

2010-01-01

267

Experimental and Monte Carlo simulated spectra of a liquid-metal-jet x-ray source.  

PubMed

A prototype x-ray system based on a liquid-metal-jet anode was evaluated within the framework of the LABSYNC project. The generated spectrum was measured using a CZT-based spectrometer and was compared with spectra simulated by three Monte Carlo codes: MCNPX, PENELOPE and EGS5. Notable differences in the simulated spectra were found. These are mainly attributable to differences in the models adopted for the electron-impact ionization cross section. The simulation that more closely reproduces the experimentally measured spectrum was provided by PENELOPE. PMID:24973466

Marziani, M; Gambaccini, M; Di Domenico, G; Taibi, A; Cardarelli, P

2014-09-01

268

Modelling the interactions between a thermal plasma flow and a continuous liquid jet in a suspension spraying process  

NASA Astrophysics Data System (ADS)

This paper describes an investigation of the suspension plasma spraying process by modelling on small scales. The interactions between a continuous jet of pure water and an Ar/H2 plasma jet were simulated using only NAVIER STOKES and heat equations. The behaviour of such fluids in interaction was analysed during the penetration of the liquid into the gas flow. The film of the interactions shows a complex breakup with a significant variation in WEBER number.

Meillot, E.; Vincent, S.; Caruyer, C.; Damiani, D.; Caltagirone, J. P.

2013-06-01

269

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

270

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

271

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

272

Formation and post-formation dynamics of bacterial biofilm streamers as highly viscous liquid jets  

PubMed Central

It has been recently reported that in presence of low Reynolds number (Re ? 1) transport, preformed bacterial biofilms, several hours after their formation, may degenerate in form of filamentous structures, known as streamers. In this work, we explain that such streamers form as the highly viscous liquid states of the intrinsically viscoelastic biofilms. Such “viscous liquid” state can be hypothesized by noting that the time of appearance of the streamers is substantially larger than the viscoelastic relaxation time scale of the biofilms, and this appearance is explained by the inability of a viscous liquid to withstand external shear. Further, by identifying the post formation dynamics of the streamers as that of a viscous liquid jet in a surrounding flow field, we can interpret several unexplained issues associated with the post-formation dynamics of streamers, such as the clogging of the flow passage or the exponential time growth of streamer dimensions. Overall our manuscript provides a biophysical basis for understanding the evolution of biofilm streamers in creeping flows. PMID:25410423

Das, Siddhartha; Kumar, Aloke

2014-01-01

273

Formation and post-formation dynamics of bacterial biofilm streamers as highly viscous liquid jets.  

PubMed

It has been recently reported that in presence of low Reynolds number (Re ? 1) transport, preformed bacterial biofilms, several hours after their formation, may degenerate in form of filamentous structures, known as streamers. In this work, we explain that such streamers form as the highly viscous liquid states of the intrinsically viscoelastic biofilms. Such "viscous liquid" state can be hypothesized by noting that the time of appearance of the streamers is substantially larger than the viscoelastic relaxation time scale of the biofilms, and this appearance is explained by the inability of a viscous liquid to withstand external shear. Further, by identifying the post formation dynamics of the streamers as that of a viscous liquid jet in a surrounding flow field, we can interpret several unexplained issues associated with the post-formation dynamics of streamers, such as the clogging of the flow passage or the exponential time growth of streamer dimensions. Overall our manuscript provides a biophysical basis for understanding the evolution of biofilm streamers in creeping flows. PMID:25410423

Das, Siddhartha; Kumar, Aloke

2014-01-01

274

Interaction of a liquid flow around a micropillar with a gas jet D. Elcock, J. Jung, C.-J. Kuo, M. Amitay, and Y. Pelesa)  

E-print Network

Interaction of a liquid flow around a micropillar with a gas jet D. Elcock, J. Jung, C.-J. Kuo, M. The jet was injected from a 25 lm wide slit on the downstream side of a 150 lm diameter pillar. The liquid. Amitay, and Y. Pelesa) Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer

Peles, Yoav

275

Flash soft radiography - Its adaptation to the study of breakup mechanisms of liquid jets into high-density gas  

Microsoft Academic Search

Liquid-jet development, structure, propagation and disintegration radiographic characterizations require thicker X-ray windows as test chamber pressures increase; these windows absorb soft X-rays and diminish image contrast. Attention is presently given to a high-intensity flash soft X-ray generator with 120 nsec pulse duration at FWHM. The levels of imaging performance thus achievable are illustrated by various flash radiographs of liquid-injection phenomena

P. Krehl; D. Warken

1991-01-01

276

Periodically plunging foil near a free surface  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

277

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

278

Cleaning of soft-solid soil layers on vertical and horizontal surfaces by stationary coherent impinging liquid jets  

E-print Network

and polymethylmethacrylate (Perspex) substrates; (ii) Xanthan gum on stainless steel; and (iii) petroleum jelly on glass. The liquid stream nozzle sizes, mass and volumetric flow rates and mean jet velocities investigated were: PVA, 2 mm, 17-50 g s^-1 (0.06-0.139 m^3 h^-1...

Wilson, D. I.; Atkinson, P.; Köhler, H.; Mauermann, M.; Stoye, H.; Suddaby, K.; Wang, T.; Davidson, J. F.; Majschak, J. -P.

2014-02-03

279

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

NASA Technical Reports Server (NTRS)

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

Labus, T. L.

1977-01-01

280

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

281

Study of the application of fine high-pressure liquid jets for cutting slits in rocks  

Microsoft Academic Search

Conclusions  \\u000a \\u000a \\u000a \\u000a 1. \\u000a \\u000a Fine high-pressure liquid jets at a pressure of 200 MPa or more provide slit cutting in all rocks with different compositions,\\u000a mechanical properties, structure, and they may be used in creating slits in the rock mass, i.e., initiators for directed hydraulic\\u000a breaking.\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a Over the outer surface of the slit and in the same plane as the high-pressure

O. I. Grebennik; L. V. Zvorygin

1989-01-01

282

Modeling the Restraint of Liquid Jets by Surface Tension in Microgravity  

NASA Technical Reports Server (NTRS)

An axisymmetric phase field model is developed and used to model surface tension forces on liquid jets in microgravity. The previous work in this area is reviewed and a baseline drop tower experiment selected 'for model comparison. A mathematical model is developed which includes a free surface. a symmetric centerline and wall boundaries with given contact angles. The model is solved numerically with a compact fourth order stencil on a equally spaced axisymmetric grid. After grid convergence studies, a grid is selected and all drop tower tests modeled. Agreement was assessed by comparing predicted and measured free surface rise. Trend wise agreement is good but agreement in magnitude is only fair. Suspected sources of disagreement are suspected to be lack of a turbulence model and the existence of slosh baffles in the experiment which were not included in the model.

Chato, David J.; Jacqmim, David A.

2001-01-01

283

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

284

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

285

High-power liquid-lithium jet target for neutron production  

E-print Network

A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the 7Li(p,n)7Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy (BNCT). The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm3) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the 7Li(p,n) neutron yield, energy distribution and angular distribution. Liquid lithium is circulated through the target loop at ~200oC and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of > 4 kW/cm2 and volume power density of ~ 2 MW/cm3 at a lithium flow of ~4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91- 2.5 MeV, 1-2 mA) at SARAF.

S. Halfon; A. Arenshtam; D. Kijel; M. Paul; D. Berkovits; I. Eliyahu; G. Feinberg; M. Friedman; N. Hazenshprung; I. Mardor; A. Nagler; G. Shimel; M. Tessler; I. Silverman

2013-11-13

286

High-power liquid-lithium jet target for neutron production  

NASA Astrophysics Data System (ADS)

A compact liquid-lithium target (LiLiT) was built and tested with a high-power electron gun at the Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the 7Li(p,n)7Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy. The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm3) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the 7Li(p,n) neutron yield, energy distribution, and angular distribution. Liquid lithium is circulated through the target loop at ˜200 °C and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of >4 kW/cm2 and volume power density of ˜2 MW/cm3 at a lithium flow of ˜4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91-2.5 MeV, 1-2 mA) at SARAF.

Halfon, S.; Arenshtam, A.; Kijel, D.; Paul, M.; Berkovits, D.; Eliyahu, I.; Feinberg, G.; Friedman, M.; Hazenshprung, N.; Mardor, I.; Nagler, A.; Shimel, G.; Tessler, M.; Silverman, I.

2013-12-01

287

High-power liquid-lithium jet target for neutron production.  

PubMed

A compact liquid-lithium target (LiLiT) was built and tested with a high-power electron gun at the Soreq Nuclear Research Center. The lithium target, to be bombarded by the high-intensity proton beam of the Soreq Applied Research Accelerator Facility (SARAF), will constitute an intense source of neutrons produced by the (7)Li(p,n)(7)Be reaction for nuclear astrophysics research and as a pilot setup for accelerator-based Boron Neutron Capture Therapy. The liquid-lithium jet target acts both as neutron-producing target and beam dump by removing the beam thermal power (>5 kW, >1 MW/cm(3)) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the (7)Li(p,n) neutron yield, energy distribution, and angular distribution. Liquid lithium is circulated through the target loop at ~200 °C and generates a stable 1.5 mm-thick film flowing at a velocity up to 7 m/s onto a concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power areal densities of >4 kW/cm(2) and volume power density of ~2 MW/cm(3) at a lithium flow of ~4 m/s while maintaining stable temperature and vacuum conditions. The LiLiT setup is presently in online commissioning stage for high-intensity proton beam irradiation (1.91-2.5 MeV, 1-2 mA) at SARAF. PMID:24387433

Halfon, S; Arenshtam, A; Kijel, D; Paul, M; Berkovits, D; Eliyahu, I; Feinberg, G; Friedman, M; Hazenshprung, N; Mardor, I; Nagler, A; Shimel, G; Tessler, M; Silverman, I

2013-12-01

288

Impingement heat transfer and recovery effect with submerged jets of large Prandtl number liquid—I. Unconfined circular jets  

Microsoft Academic Search

Experimental study was performed to characterize recovery factor and heat transfer coefficient on vertical heaters impinged by submerged circular transformer oil jets issued from both pipe and orifice nozzles. Radial distributions of local recovery factor were determined at various Reynolds numbers and nozzle-to-plate spacings, and compared with numerical result. Local Nusselt number at stagnation point was found to be proportional

T. Gomi; Q. ZHENG; S. C. LEE

1997-01-01

289

Detailed simulation of primary atomization mechanisms in Diesel jet sprays (isolated identification of liquid jet tip effects)  

Microsoft Academic Search

In this study, the atomization characteristics of Diesel jet front tip have been investigated to elucidate the physical mechanisms by detailed numerical simulation. The computations are carried out with the finest grid resolutions ever that can resolve the final droplet generation by surface tension. The numerical methods are based on level-set interface tracking. The methods were validated by test cases

J. Shinjo; A. Umemura

2011-01-01

290

Non-thermal processes on ice and liquid micro-jet surfaces  

NASA Astrophysics Data System (ADS)

The primary focus of this research is to investigate non-thermal processes occurring on ice surfaces and the photo-ejection of ions from liquid surfaces. Processes at the air-water/ice interface are known to play a very important role in the release of reactive halogen species with atmospheric aerosols serving as catalysts. The ability to make different types of ice with various morphologies, hence, different adsorption and surface properties in vacuum, provide a useful way to probe the catalytic effect of ice in atmospheric reactions. Also, the use of the liquid jet technique provides the rare opportunity to probe liquid samples at the interface; hitherto impossible to investigate with traditional surface science techniques. In Chapter 2, the effect of ice morphology on the release of reactive halogen species from photodissociation of adsorbed organic halides on ice will be presented. Quantum state resolved measurements of neutral atomic iodine from the photon irradiation of submonolayer coverages of methyl iodide adsorbed on low temperature water ice were conducted. Temperature programmed desorption (TPD) studies of methyl iodide adsorbed on ice were performed to provide information on the effect of ice morphology on the adsorption of submonolayer methyl iodide. The interaction and autoionization of HCl on low-temperature (80{140 K) water ice surfaces has been studied using low-energy (5-250 eV) electron-stimulated desorption (ESD) and temperature programmed desorption (TPD). A detailed ESD study of the interactions of low concentrations of HCl with low-temperature porous amorphous solid water (PASW), amorphous solid water (ASW) and crystalline ice (CI) surfaces will be presented in Chapter 3. The ESD cation yields from HCl adsorbed on ice, as well as the coverage dependence, kinetic energy distributions and TPD measurements were all monitored. Probing liquid surface using traditional surface science technique is usually difficult because of the problem of keeping the liquid surface clean and the distortion of information by the interference of equilibrium dense vapor above the liquid. By using the liquid jet technique the ejection of ions from surface of micron sized liquid can be adequately probed with a linear time-of-flight mass spectrometer. The photoionization of pure water and aqueous solutions of NaOH, NaCl and HCl is presented in Chapter 4. The aim of this investigation was to provide a fundamental understanding of the structure of water/vacuum interfaces. In Chapter 5, the ejection of ions from salt solutions containing divalent cations is also presented. The goal of the experiment was to figure out the solvation structure and reaction dynamics of divalent metal ions, M2+ on the surface of aqueous solution. A lot of work has been done in the gas phase either by a pickup-type cluster source or by collision induced dissociation of ejected ions from electrospray. For the first time the direct monitoring of ions ejected from liquid into gas phase is explored. Possible ejection mechanisms for the ejection of cations are discussed extensively in both Chapters 4 and 5. The results presented in this thesis is a combination of experiments performed at the Georgia Institute of Technology and the Pacific Northwest National Laboratory (PNNL) which includes experiments on ice and micro-jet respectively. The results in Chapters 2 and 3 have been submitted to the Journal of Chemical Physics and the Journal of Physical Chemistry respectively. It is important to note that the data presented in Chapter 3 was originally taken by Dr Janine Herring-Captain as part of her thesis work. It is also presented in this thesis due to effort in analyzing the data and preparation of the submitted manuscript. Chapter 4 and 5 represents papers which will also be submitted for publication in the open scientific literature. All the work leading to the results presented in these two chapters were done during my visit to PNNL and I would like to acknowledge that the instrumentation and data acquisition were done in collaboration with Nikolai Pet

Olanrewaju, Babajide O.

291

INTERNATIONAL SYMPOSIUM ON FLOW VISUALIZATION (1998) VISUALIZATION OF LIQUID METAL, ARC, AND JET  

E-print Network

and constricted through a nozzle, forms a superheated, ionized plasma jet. With temperatures up to 20,000 K, this plasma jet can vaporize most materials. It slices handily through steel plate, ejecting a molten stream of iron and ferrous oxides. The plasma jet thus provides both the thermal energy to melt the metal

Settles, Gary S.

292

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.

293

Influence of the Development History of Nozzle Wall Boundary Layer upon Wave Generation on a Liquid Jet Free Surface  

NASA Astrophysics Data System (ADS)

The relation between the development of the wall boundary layer in a convergent nozzle and free surface waves on the emanated liquid jet has been investigated experimentally. In the convergent nozzle, which forms a water jet along a flat back wall, the velocity profiles of the wall boundary layer were measured using a laser Doppler velocimeter with jet average velocities of U0 = 5, 10 and 15 m/s. The property of free-surface waves and the intermittency factor of free surface fluctuations were also determined by photography and an optical measurement technique, using laser beam refraction on the jet surface. For the lowest velocity case U0 = 5 m/s, the mean velocity profiles of the boundary layer under the pressure gradient in the convergent nozzle indicated an inverse transition from turbulent to laminar boundary layer, so-called relaminarization. On the other hand, for the higher velocity case U0 ? 10 m/s, the relaminarization in the convergent section became incomplete. For these cases, the turbulent intensity near the wall increased significantly and the nozzle-exit boundary layer was restored quickly to a turbulent profile for a short parallel section immediately upstream of the nozzle exit plane. The increase in the velocity fluctuation near the wall promotes wave generation downstream of the nozzle exit plane. Therefore, the intermittence of the wave packet almost disappeared and the jet free surface was covered with continuous capillary waves when the turbulent boundary layer was separated from the nozzle exit.

Itoh, Kazuhiro; Kumamaru, Hiroshige

294

Transition from inspiral to plunge in binary black hole coalescences  

E-print Network

Combining recent techniques giving non-perturbative re-summed estimates of the damping and conservative parts of the two-body dynamics, we describe the transition between the adiabatic phase and the plunge, in coalescing binary black holes with comparable masses moving on quasi-circular orbits. We give initial dynamical data for numerical relativity investigations, with a fraction of an orbit left, and provide, for data analysis purposes, an estimate of the gravitational wave-form emitted throughout the inspiral, plunge and coalescence phases.

Alessandra Buonanno; Thibault Damour

2000-01-07

295

Anaesthetic management in a case of huge plunging ranula  

PubMed Central

Plunging ranula is a rare form of mucous retention cyst arising from submandibular and sublingual salivary glands, which may occasionally become huge occupying the whole of the floor of the mouth and extending into the neck, thus, restricting the neck movement as well as disfiguring the normal airway anatomy. Without fiberoptic assistance, blind or retrograde nasal intubation remains valuable choices in this type of situation. Here, we present a case of successful management of airway by blind nasal intubation in a patient posted for excision of a huge plunging ranula.

Sheet, Jagabandhu; Mandal, Anamitra; Sengupta, Swapnadeep; Jana, Debaleena; Mukherji, Sudakshina; Swaika, Sarbari

2014-01-01

296

First results of Minimum Fisher Regularisation as unfolding method for JET NE213 liquid scintillator neutron spectrometry  

Microsoft Academic Search

At JET, the NE213 liquid scintillator is being validated as a diagnostic tool for spectral measurements of neutrons emitted from the plasma. Neutron spectra have to be unfolded from the measured pulse-height spectra, which is an ill-conditioned problem. Therefore, use of two independent unfolding methods allows for less ambiguity on the interpretation of the data. In parallel to the routine

Jan Mlynar; John M. Adams; Luciano Bertalot; Sean Conroy

2005-01-01

297

Transient conjugate heat transfer from a hemispherical plate during free liquid jet impingement on the convex surface  

Microsoft Academic Search

This paper considers the analysis of transient heating of a hemispherical solid plate of finite thickness during impingement\\u000a of a free liquid jet. A constant heat flux was imposed at the inner surface of the hemispherical plate at t = 0 and heat transfer was monitored for the entire duration of the transient until a steady state condition was reached.\\u000a Calculations were

Muhammad M. RahmanCesar; Cesar F. Hernandez

2011-01-01

298

Evaluation of liquid-metal jets as the conductor in a rep-rated, exploding-fuse opening switch  

Microsoft Academic Search

A repetitive, high-power opening switch technique for use in pulsed power applications using inductive energy storage is presented, along with data which demonstrate performance characteristics. This technique uses jets of a liquid conductor to replace the solid metal fuses in exploding-fuse opening-switch designs. High-power switching characteristics such as interrupt current, holdoff voltage, and resistance change are presented, along with information

William E. Ansley; M. Frank Rose

1996-01-01

299

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

300

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

301

Binary black holes coalescence: transition from adiabatic inspiral to plunge  

E-print Network

Using two recent techniques giving non-perturbative re-summed estimates of the damping and of the conservative part of the dynamics of two-body systems, we describe the transition between adiabatic inspiral and plunge in binary non-spinning black holes moving along quasi-circular orbits.

Alessandra Buonanno; Thibault Damour

2000-11-14

302

Gravity Waves from Extreme-Mass-Ratio Plunges into Kerr Black Holes  

E-print Network

Massive objects orbiting a near-extreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be related by a conformal map to a circular orbit. Conformal symmetry of the near-horizon region is then used to compute the gravitational radiation produced during the plunge phase.

Shahar Hadar; Achilleas P. Porfyriadis; Andrew Strominger

2014-03-12

303

Gravity Waves from Extreme-Mass-Ratio Plunges into Kerr Black Holes  

E-print Network

Massive objects orbiting a near-extreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be related by a conformal map to a circular orbit. Conformal symmetry of the near-horizon region is then used to compute the gravitational radiation produced during the plunge phase.

Hadar, Shahar; Strominger, Andrew

2014-01-01

304

GEOLOGY, December 2009 1067 Hyperpycnal flows are turbid river plumes that can plunge to  

E-print Network

GEOLOGY, December 2009 1067 ABSTRACT Hyperpycnal flows are turbid river plumes that can plunge, and plunging zone before becoming a turbidity current. These zones can extend tens of kilometers offshore also suggest that the criterion used to identify plunging hyperpycnal flows (a flow density in excess

305

BOULDER TILL FILLED PLUNGE POOLS FOUND AT THE WORLD TRADE CENTER SITE, NYC, NY  

E-print Network

BOULDER TILL FILLED PLUNGE POOLS FOUND AT THE WORLD TRADE CENTER SITE, NYC, NY MOSS, Cheryl, J that the SE corner of the site is underlain by 2 large plunge pools and scores of potholes formed by stream, resisted erosion, plunge pools, whirlpools, potholes, and "waterslides" were selectively carved 17m down

Merguerian, Charles

306

American Institute of Aeronautics and Astronautics Effects of Unequal Pitch and Plunge Airfoil Motion Frequency on  

E-print Network

American Institute of Aeronautics and Astronautics 1 Effects of Unequal Pitch and Plunge Airfoil-Patterson AFB, OH 45433 Departing from mainstream pitching/plunging airfoil literature, we consider scenarios where the frequencies of the plunge and the pitch are not equal. The motivation is, first, consideration

307

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

E-print Network

Three-dimensional Large Eddy Simulation of air entrainment under plunging breaking waves Pierre simulating three-dimensional plunging breaking waves by solving the Navier-Stokes equations, in air and water tool is used for the complete de- scription of the plunging breaking processes including overturning

Paris-Sud XI, Université de

308

High-order accurate simulations of unsteady flow past plunging and pitching airfoils Chunlei Liang a,  

E-print Network

High-order accurate simulations of unsteady flow past plunging and pitching airfoils Chunlei Liang: Spectral difference method Plunging Pitching Micro Air Vehicle a b s t r a c t This paper presents simulations of unsteady flow past plunging and pitching airfoils using a high-order spectral difference (SD

Jameson, Antony

309

Occurrence and origin of submarine plunge pools at the base of the US continental slope  

E-print Network

Occurrence and origin of submarine plunge pools at the base of the US continental slope Simon E are a series of discrete `plunge pools' with associated downslope topographic ramparts. We have used new bathymetric data to create our own data base (of over 150 examples) and systematically analyse plunge pool

Hogg, Andrew

310

Gravity waves from extreme-mass-ratio plunges into Kerr black holes  

NASA Astrophysics Data System (ADS)

Massive objects orbiting a near-extreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be related by a conformal map to a circular orbit. Conformal symmetry of the near-horizon region is then used to compute the gravitational radiation produced during the plunge phase.

Hadar, Shahar; Porfyriadis, Achilleas P.; Strominger, Andrew

2014-09-01

311

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

SciTech Connect

Jet impingement has been an attractive cooling option in a number of industries over the past few decades. Over the past 15 years, jet impingement has been explored as a cooling option in microelectronics. Recently, interest has been expressed by the automotive industry in exploring jet impingement for cooling power electronics components. This technical report explores, from a modeling perspective, both single-phase and boiling jet impingement cooling in power electronics, primarily from a heat transfer viewpoint. The discussion is from the viewpoint of the cooling of IGBTs (insulated-gate bipolar transistors), which are found in hybrid automobile inverters.

Narumanchi, S. V. J.; Hassani, V.; Bharathan, D.

2005-12-01

312

RANS MODELING OF GAS JET IMPINGING ONTO A DEFORMABLE LIQUID INTERFACE  

Microsoft Academic Search

??????? ???????? ???? ?????? ?????? ??? ????? ?? ?? ??? ????? ????? ???????? . ???? ??? ??? ?????? ??? ?? ???? ???? ??????? ????????? ???? ?????? ????? ???? ????? ?????? ?? ???? ??????? ???????? . The present paper introduces a numerical model for one of the most important fluid-fluid interaction problems in industrial engineering applications, mainly a gas jet impinging

A. Balabel

2007-01-01

313

tion of Liquid-Metal Jets as the Conductor in a ated, Exploding-Fuse Opening Switc  

E-print Network

Abstract-A repetitive, high-power opening switch technique for use in pulsed power applications using inductive energy storage is presented, along with data which demonstrate performance characteristics. This technique uses jets of a liquid conductor to replace the solid metal fuses in exploding-fuse opening-switch designs. High-power switching characteristics such as interrupt current, holdoff voltage, and resistance change are presented, along with information on how these characteristics change as jet length and circuit parameters are varied. A simulated load is used to demonstrate that exploding liquid-metal jets are feasible replacements for solid-fuse conductors in realistic applications. Likewise, the switching facility has been rep-rated in a two-pulse scenario to show its primary advantage over solid-fuse switches. The use of a highspeed camera to monitor the expansion of the mercury column upon vaporization is also described. Radial expansion velocities have been extracted from the images and are correlated with the electrical data. I.

William E. Ansley; M. Frank Rose

314

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

315

Bubble sweeping and jet flows during nucleate boiling of subcooled liquids  

Microsoft Academic Search

An experimental investigation was conducted to investigate nucleate boiling on a very fine heating wire. By using zoom routine and CCD camera system, the dynamical process of nucleate boiling was visually observed. Sweeping bubbles and several modes of jet flows were described and discussed. For some cases, big bubbles, small bubbles, sweeping bubbles and jet flows coexisted in boiling system,

H. Wang; X. F. Peng; B. X. Wang; D. J. Lee

2003-01-01

316

Role played by the interfacial shear in the instability mechanism of a viscous liquid jet surrounded by a viscous gas in a pipe  

Microsoft Academic Search

The role of interfacial shear in the onset of instability of a cylindrical viscous liquid jet in a viscous gas surrounded by a coaxial circular pipe is elucidated by use of an energy budget associated with the disturbance. It is shown that the shear force at the liquid gas interface retards the Rayleigh-mode instability which leads to the breakup of

S. P. Lin; J. N. Chen

1998-01-01

317

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

318

Visco Jet Joule-Thomson Device Characterization Tests in Liquid Methane  

NASA Technical Reports Server (NTRS)

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

Jurns, John M.

2009-01-01

319

Experimental Investigation of the Deposition of Liquid Droplets on the Walls of a Vertical Cylindrical Channel from Wall Gas-Droplet Jets  

Microsoft Academic Search

The results are given of an experimental investigation of the formation of liquid films from wall gas-droplet jets under quasi-isothermal conditions. The experiments are performed in the initial segment of a round cylindrical tube under conditions of varying cocurrent-flow parameter m = ?sws\\/?0w0 and concentration of liquid droplets. The instantaneous thickness of the liquid film is measured by a capacitive

V. I. Terekhov; A. F. Serov; K. A. Sharov; A. D. Nazarov

2003-01-01

320

Drop-size distribution for crosscurrent breakup of a liquid jet in a convective airstream  

E-print Network

Experimental investigations have been completed in the study of a simulated fuel injector system implementing an airblast atomization process called a jet in a crossflow as the primary means of fuel atomization. To complete these studies...

Lyn, Gregory Michael

2012-06-07

321

On-Line Optimization for Internal Plunge Grinding  

Microsoft Academic Search

An on-line optimization system was developed for cylindrical plunge grinding to minimize production time while ensuring part quality requirements. The system is capable of optimizing the grinding and dressing parameters in response to in-process and post-process measurements which characterize the process and update the process model. As compared with the previous system, the present one encompasses a more complete set

G. Xiao; S. Malkin

1996-01-01

322

Steeply plunging folds in the sealy range, southern Alps  

Microsoft Academic Search

Large steeply plunging folds are very clearly exposed in rugged country near Mt Cook, New Zealand. The axes of abundant minor folds are roughly parallel to those of the major folds. The strata consist of metagreywacke,belonging to the prehnite-pumpellyite mineralogical facies, and of associated quartzo-feldspathic schist, the latter concentrated within a belt some 4,000 ft wide bordered on both sides

A. R Lillie; B. M. Gunn

1964-01-01

323

External and internal flow fields of plunging breakers  

Microsoft Academic Search

This first stage of a laboratory study of the turbulent flow-field induced by wave-breaking involves the application of a flow-visualization technique from which external appearance and internal flow-structures of the surf zone have been examined. Plunging breakers were generated in a wave flume, whilst suitable light sources were deployed. To trace the water particle motion, fluorescent coatings in combination with

C. Lin; H. H. Hwung

1992-01-01

324

Transitions in the vortex wake behind the plunging profile  

NASA Astrophysics Data System (ADS)

In this study we investigate numerically the vortex wake formation behind the profile performing simple harmonic motion known in the literature as plunging. This research was inspired by the flapping motion which is appropriate for birds, insects and fishes. We assume the two dimensional model of flow. Depending on the parameters such as plunging amplitude, frequency and the Reynolds number, we demonstrate many different types of vortex street behind the profile. It is well known that the type of vortex wake determines the hydrodynamic forces acting on the profile. Dependences of the plunging amplitude, the Strouhal number and various topology vortices are established by constructing the phase transition diagram. The areas in the diagram related to the drag, thrust, and lift force generation are captured. We notice also the areas where the vorticity field is disordered. The disordered vorticity field does not allow maintenance of the periodic forces on the profile. An increase in the Reynolds number leads to the transition of the vortex wake behind the profile. The transition is caused by the phenomenon of boundary layer eruption. Further increase of the Reynolds number causes the vortex street related to the generation of the lift force to vanish.

Koz?owski, Tomasz; Kudela, Henryk

2014-12-01

325

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

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

326

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

SciTech Connect

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

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

2010-02-22

327

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

328

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

Microsoft Academic Search

We demonstrate stable high-brightness operation of an electron-impact water-jet-anode soft x-ray source. A 30 kV, 7.8 W electron beam is focused onto a 20 mum diameter jet resulting in water-window oxygen line emission at 525 eV\\/2.36 nm with a brightness of 3.0×109 ph\\/(s×mum2×sr×line). Monte Carlo-based modeling shows good quantitative agreement with the experiments. The source has potential to increase the

P. Skoglund; U. Lundstroem; U. Vogt; H. M. Hertz

2010-01-01

329

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

330

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

331

DYNAMICS OF LIQUID METAL JETS PENETRATING A STRONG MAGNETIC FIELD IN HIGH-POWER COLLIDERS  

E-print Network

for lithium and water jets [4]. 2 BEAM/TARGET SYSTEM The parameters of the proton beam and solenoid coil parameters consist of a proton energy Ep = 16 GeV, number of protons in one bunch Np 1015 , bunch beam power is determined by two conditions: first, V should be high enough to remove the energy deposited by the proton

Harilal, S. S.

332

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

NASA Astrophysics Data System (ADS)

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

Huh, Jun-Young

333

GRB 110328A/Swift J164449.3+573451: The Tidal Obliteration of a Deeply Plunging Star?  

NASA Astrophysics Data System (ADS)

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.; Troja, E.; Lodato, G.

2011-11-01

334

GRB 110328A/Swift J164449.3+573451: The Tidal Obliteration of a Deeply Plunging Star?  

E-print Network

We examine the tidal disruption event scenario to explain Sw 1644+57, a powerful and persistent X-ray source which suddenly became active as GRB 110328A. The precise localizations by HST and Chandra at the center of a z=0.354 galaxy argue for activity of the central engine as the underlying cause. We look at the suggestion by Bloom et al of the possibility of a tidal disruption event (TDE). We derive estimates for the accretion rate onto the expected massive black hole in the galactic center. 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 - the orbit must be deeply plunging or else the powerful jet we are observing could not be produced, and the Swift/BAT rate would be too high. For nominal parameters without deep plunging, the disk accretion of the stellar remnants could only produce a disk accreting at ~0.01 Eddington. In addition, the predicted event rate in BAT for normal TDEs would be ~30/yr, taking into a...

Cannizzo, J K; Lodato, G

2011-01-01

335

Cold blocking of the channel in a gas-liquid mixer by hot fuel jets  

Microsoft Academic Search

This article examines cold blocking in a circular channel with separate feeds for the oxidant and fuel and diffusion burning on the latter. Jets of T-1 kerosene at a temperature of +20°C were injected into a gas channel of a mixer with an internal diameter of 21 mm at angles of 60 and 90° and a distance of 28 mm

M. E. Rudyak

1983-01-01

336

Toward two-phase simulation of the primary breakup of a round liquid jet by a coaxial o w of gas  

Microsoft Academic Search

1. Motivation and objectives Two-phase o ws are very common in nature and technical processes such as ocean waves, tire splash, and combustion devices. Among them, the atomization of liquid jets or sheets by gas streams has received much attention due to its direct applicability to the design of combustion chambers. However, it is challenging to model such a phenomenon

D. Kim; O. Desjardins; M. Herrmann; P. Moin

337

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

Microsoft Academic Search

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

Jorge C. Lallave Cortes

2009-01-01

338

Theoretical model for high-power diamond laser optics using high-velocity liquid-metal jet impingement cooling  

NASA Astrophysics Data System (ADS)

In 1988 I presented a paper, `Fly's Eye Modular Optic,' in the Los Angeles Symposium that described an optic for high power laser systems that provided for a modular system of hexagonal components that were independently cooled using a high velocity jet pointed normal to the back surface of the optical faceplate. In this paper we look at the use of diamond optical materials in concert with high velocity jet impingement heat transfer of various liquid metal mediums. By using this combination of techniques and materials we can push the laser damage threshold of optical components to even higher levels of absorbed flux density. The thrust of this paper is to develop a theoretical model for use on optical elements subject to very high continuous flux density lasers and to evaluate the use of commercial diamond substrates with conventional optical thin films and conventional substrates with CVD diamond films. In order to assume the very high absorbed flux densities, it is necessary to have a heat transfer technique capable of maintaining the optical component at a stable temperature and below the damage threshold of the optical materials. For the more common materials, thermal shock and subsequent failure in bi-axial shear have proven to be one of the major constituents of the optical damage. In this paper we look at the thermal shock, vis-a-vis, the melting point of some of the materials.

Palmer, James R.

1993-02-01

339

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

NASA Astrophysics Data System (ADS)

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 counterswirled jets where all the air was supplied through the front unit of the chamber. However, the tests did not make it possible to solve some of the problems which arise when operating under full-scale conditions, such as the required high combustion efficiency under variable operating conditions of a gas turbine plant; elimination of soot formation at the walls of the stabilizer and the internal surfaces of the pipes supplying fuel to the atomizers; and a decrease in smoking under conditions of excess air factor.

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

1986-03-01

340

Unequal Mass Binary Black Hole Plunges and Gravitational Recoil  

E-print Network

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 = M_1/M_2 = {1,0.85,0.78,0.55,0.32}, or equivalently, with reduced mass parameters $\\eta=M_1M_2/(M_1+M_2)^2 = {0.25, 0.248, 0.246, 0.229, 0.183}$. For each case, the initial binary orbital parameters are chosen from the Cook-Baumgarte equal-mass ISCO configuration. We show waveforms of the dominant l=2,3 modes and compute estimates of energy and angular momentum radiated. For the plunges from the close separations considered, we measure kick velocities from gravitational radiation recoil in the range 25-82 km/s. Due to the initial close separations our kick velocity estimates should be understood as a lower bound. The close configurations considered are also likely to contain significant eccentricities influencing the recoil velocity.

F. Herrmann; I. Hinder; D. Shoemaker; P. Laguna

2006-01-06

341

The Eye of the Storm: Light from the Inner Plunging Region of Black Hole Accretion Discs  

E-print Network

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 this plunging region. In this work, 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 this neglected inner light only has a modest effect (this bias is less than typical observational systematic errors). For rapidly spi...

Zhu, Yucong; Narayan, Ramesh; Kulkarni, Akshay K; Penna, Robert F; McClintock, Jeffrey E

2012-01-01

342

Beating the jetting regime Beating the jetting regime  

E-print Network

guiding principles to break up liquid jets in cases where dripping is difficult to achieve. Keywords-uniform and different from the size of the inner tip2,3 . The mechanism of the dripping and jetting regimes are quiteBeating the jetting regime Beating the jetting regime Alban Sauret1, 2 and Ho Cheung Shum2 1

Paris-Sud XI, Université de

343

Experimental study of flow field around a plunging flexible hydrofoil  

NASA Astrophysics Data System (ADS)

Recent developments in micro air vehicles (MAVs) have led to the improvement of computational fluid dynamics (CFD) simulations capable of simulating flexible flapping wing phenomena. For validation of these simulations, an experimental methodology is applied to characterize the flow physics involved with an immersed flexible flapping hydrofoil. Using a one-degree of freedom crank-shaft system, a silicone hydrofoil was actuated to flap under various kinematic conditions. The hydrofoil was subject to active plunging and passive pitching motion in both water and aqueous glycerin solutions. Phase-locked particle image velocimetry (PIV) measurements were obtained around the flapping hydrofoil. These measurements, along with force measurements using a six-axis load cell, are used to compare the results with those of the numerical simulations. By comparing the hydrofoil deformation, vortex evolution and force generation, good agreements between CFD and experimental results were observed.

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

2011-11-01

344

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

345

Copyright 1998,AmericanInstitute of Aeronautics and Astronautics, Inc. Calculation of Plunging Breakers with A Fully-Implicit  

E-print Network

Copyright© 1998,AmericanInstitute of Aeronautics and Astronautics, Inc. Calculation of Plunging Abstract A new algorithm for simulating the plunging breaker is described. The approach is a fully solutions and the tank measurements for the plunging breaker generated by a piston-type wavemaker. Excellent

Jameson, Antony

346

Submitted to the Journal of Hydraulic Engineering, ASCE, January, 2006 NOTE ON THE ANALYSIS OF PLUNGING OF DENSITY FLOWS  

E-print Network

OF PLUNGING OF DENSITY FLOWS Gary Parker1 , Member, ASCE and Horacio Toniolo2 ABSTRACT This note is devoted to the correction of an error in a calculation contained in a classical published paper on the plunging of river, according to which not only the ratio of underflow thickness just after plunging to depth just before

Parker, Gary

347

Flow structure and performance of a flexible plunging airfoil  

NASA Astrophysics Data System (ADS)

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

Akkala, James Marcus

348

Bouncing of a jet off a Newtonian liquid surface Matthew Thrasher, Sunghwan Jung,  

E-print Network

by pouring mineral oil into a pan of mineral oil.1 1 M. Thrasher, S. Jung, Y. K. Pang, C.-P. Chuu, and H. L of silicone oil of flow rate Q and viscosity is falling from height H to a bath of the same liquid, which

Texas at Austin. University of

349

Very-near-field dynamics in the injection of two-dimensional gas jets and thin liquid sheets between two parallel high-speed gas streams  

NASA Astrophysics Data System (ADS)

A numerical investigation of the velocity, pressure and vorticity fields very near the injection of flat and thin two-dimensional gas jets or liquid sheets between two parallel high-speed gas coflows is performed. The motivation of this research is to uncover some basic physical mechanisms underlying twin-fluid atomization. Conservation equations and boundary and initial conditions are presented for both single-phase jets and two-phase liquid sheet/gas-stream systems. Both infinitely thin and thick solid walls are considered. Apart from the gas Strouhal and Reynolds numbers appearing in the dimensionless single-phase flow equations, the liquid Reynolds number, the momentum flux ratio, the gas/liquid velocity ratio and the Weber number enter the two-phase flow dimensionless formulation. The classical numerical techniques for single-phase jets are supplemented with the volume-of-fluid (VOF) method for interface tracking and the continuum surface force (CSF) method to include surface tension in two-phase flow systems. Ad hoc convection algorithms in combination with a developed version of the fractional-step scheme allows a significant reduction of the numerical diffusion, maintaining localized and sharp interfaces. The action of the surface tension is correctly found via the CSF with a smoothed scalar-field approximation.

López-Pagés, Enrique; Dopazo, César; Fueyo, Norberto

2004-09-01

350

Flashing liquid jets and two-phase droplet dispersion I. Experiments for derivation of droplet atomisation correlations.  

PubMed

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 representing low to high superheat. 2D Phase-Doppler Anemometry has been utilised to characterise droplet kinematics and spray quality. Droplet size correlations have been developed for non-flashing, the transition between non-flashing and flashing, and fully flashing jets. Using high-speed shadowography, transition between regimes is defined in terms of criteria identified in the external flow structure. An overview companion paper provides a wider overview of the problem and reports implementation of these correlations into consequence models and subsequent validation. The fluid utilised throughout is water, hence droplet correlations are developed in non-dimensional form to allow extrapolation to other fluids through similarity scaling, although verification of model performance for other fluids is required in future studies. Data is reduced via non-dimensionalisation in terms of the Weber number and Jakob number, essentially representing the fluid mechanics and thermodynamics of the system, respectively. A droplet-size distribution correlation has also been developed, conveniently presented as a volume undersize distribution based on the Rosin-Rammler distribution. Separate correlations are provided for sub-cooled mechanical break-up and fully flashing jets. This form of correlation facilitates rapid estimates of likely mass rainout quantities, as well as full distribution information for more rigorous two-phase thermodynamic modelling in the future. PMID:16956721

Cleary, Vincent; Bowen, Phil; Witlox, Henk

2007-04-11

351

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

352

Review of Modeling of Liquid Precursor Droplets and Particles Injected into Plasmas and High-Velocity Oxy-Fuel (HVOF) Flame Jets for Thermal Spray Deposition Applications  

Microsoft Academic Search

This article presents a review of the current state-of-the-art in modeling of liquid chemical precursor droplets and particles\\u000a injected into high-temperature jets in the form of DC-arc plasmas and high-velocity oxy-fuel flames to form coatings. Conventional\\u000a thermal spray processes have typically utilized powders that are melted and deposited as a coating on hardware surfaces. However,\\u000a production of coatings utilizing liquid

Baki M. Cetegen; Saptarshi Basu

2009-01-01

353

Cystic lymphangioma and plunging ranula treated by OK-432 therapy: a report of two cases.  

PubMed

Among head and neck angiotumors, cystic lymphangioma occurs in infancy in most cases and it is rare in adulthood. Plunging ranula is one of the diseases which need to be distinguished from lymphangioma, though operation is the first choice therapy for both of these. In the present study, we report on 2 cases in whom we conducted intralesional injection of OK-432 for cervical lymphangioma and ranula found in 20 and 35 year-old female patients. We obtained excellent improvement. First of all, we punctured the tumors and sucked out the liquid content as much as possible, and then used OK-432 in the same volumes to those drawn out. No swelling was observed in either patient after 1 month, and cysts disappeared in CT 4 and 12 months after injection, respectively; at present, the prognosis is satisfactory, without recurrence. The intralesional injection of OK-432 is considered an effective method, as the speed of complete disappearance by this therapy is high. Cosmetically it is superb, leaving no lesions in the skin of the injection site. PMID:8203228

Ikarashi, T; Inamura, K; Kimura, Y

1994-01-01

354

Headcut retreat resulting from plunge pool erosion in a 3D landscape evolution model  

E-print Network

Headcut retreat produced by plunge pools is represented using existing concepts about this type of erosion. The model estimates retreat rates, given flow, height of the headcut, upstream slope and Manning's roughness, and ...

Flores Cervantes, Javier Homero, 1977-

2004-01-01

355

Transition from inspiral to plunge for eccentric equatorial Kerr orbits  

E-print Network

Ori and Thorne have discussed the duration and observability (with LISA) of the transition from circular, equatorial inspiral to plunge for stellar-mass objects into supermassive ($10^{5}-10^{8}M_{\\odot}$) Kerr black holes. We extend their computation to eccentric Kerr equatorial orbits. Even with orbital parameters near-exactly determined, we find that there is no universal length for the transition; rather, the length of the transition depends sensitively -- essentially randomly -- on initial conditions. Still, Ori and Thorne's zero-eccentricity results are essentially an upper bound on the length of eccentric transitions involving similar bodies (e.g., $a$ fixed). Hence the implications for observations are no better: if the massive body is $M=10^{6}M_{\\odot}$, the captured body has mass $m$, and the process occurs at distance $d$ from LISA, then $S/N \\lesssim (m/10 M_{\\odot})(1\\text{Gpc}/d)\\times O(1)$, with the precise constant depending on the black hole spin. For low-mass bodies ($m \\lesssim 7 M_\\odot$) for which the event rate is at least vaguely understood, we expect little chance (probably [much] less than 10%, depending strongly on the astrophysical assumptions) of LISA detecting a transition event with $S/N>5$ during its run; however, even a small infusion of higher-mass bodies or a slight improvement in LISA's noise curve could potentially produce $S/N>5$ transition events during LISA's lifetime.

R. O'Shaughnessy

2002-11-07

356

Trapping of magnetic flux by the plunge region of a black hole accretion disk  

Microsoft Academic Search

The existence of the radius of marginal stability means that accretion flows\\u000aaround black holes invariably undergo a transition from a MHD turbulent\\u000adisk-like flow to an inward plunging flow. We argue that the plunging inflow\\u000acan greatly enhance the trapping of large scale magnetic field on the black\\u000ahole, and therefore may increase the importance of the Blandford-Znajek (BZ)

Christopher S. Reynolds; David Garofalo; Mitchell C. Begelman

2006-01-01

357

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

Microsoft Academic Search

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

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

2006-01-01

358

Selecting a milling strategy with regard to the machine tool capabilities: application to plunge milling  

Microsoft Academic Search

The last generation of machining equipment has made innovative milling strategies, such as plunge milling tool-paths, to spread\\u000a in the industry. However, it is still difficult to evaluate whether the implementation of plunge milling will be beneficial\\u000a for a specific combination of machine tool and part to machine. The optimal parameterization is difficult to be found. Hence,\\u000a this paper gives

Matthieu Rauch; Jean-Yves Hascoet

359

First application of liquid-metal-jet sources for small-animal imaging: High-resolution CT and phase-contrast tumor demarcation  

SciTech Connect

Purpose: Small-animal studies require images with high spatial resolution and high contrast due to the small scale of the structures. X-ray imaging systems for small animals are often limited by the microfocus source. Here, the authors investigate the applicability of liquid-metal-jet x-ray sources for such high-resolution small-animal imaging, both in tomography based on absorption and in soft-tissue tumor imaging based on in-line phase contrast. Methods: The experimental arrangement consists of a liquid-metal-jet x-ray source, the small-animal object on a rotating stage, and an imaging detector. The source-to-object and object-to-detector distances are adjusted for the preferred contrast mechanism. Two different liquid-metal-jet sources are used, one circulating a Ga/In/Sn alloy and the other an In/Ga alloy for higher penetration through thick tissue. Both sources are operated at 40-50 W electron-beam power with {approx}7 {mu}m x-ray spots, providing high spatial resolution in absorption imaging and high spatial coherence for the phase-contrast imaging. Results: High-resolution absorption imaging is demonstrated on mice with CT, showing 50 {mu}m bone details in the reconstructed slices. High-resolution phase-contrast soft-tissue imaging shows clear demarcation of mm-sized tumors at much lower dose than is required in absorption. Conclusions: This is the first application of liquid-metal-jet x-ray sources for whole-body small-animal x-ray imaging. In absorption, the method allows high-resolution tomographic skeletal imaging with potential for significantly shorter exposure times due to the power scalability of liquid-metal-jet sources. In phase contrast, the authors use a simple in-line arrangement to show distinct tumor demarcation of few-mm-sized tumors. This is, to their knowledge, the first small-animal tumor visualization with a laboratory phase-contrast system.

Larsson, Daniel H.; Lundstroem, Ulf; Burvall, Anna; Hertz, Hans M. [Department of Applied Physics, KTH Royal Institute of Technology/Albanova, 10691 Stockholm (Sweden); Westermark, Ulrica K.; Arsenian Henriksson, Marie [Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, 17177 Stockholm (Sweden)

2013-02-15

360

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

PubMed

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

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

2014-06-01

361

Design and Testing of an Automated System using Thermochromatic Liquid Crystals to Determine Local Heat Transfer Coefficients for an Impinging Jet  

NASA Technical Reports Server (NTRS)

Using thermochromatic liquid crystal to measure surface temperature, an automated transient method with time-varying free-stream temperature is developed to determine local heat transfer coefficients. By allowing the free-stream temperature to vary with time, the need for complicated mechanical components to achieve a step temperature change is eliminated, and by using the thermochromatic liquid crystals as temperature indicators, the labor intensive task of installing many thermocouples is omitted. Bias associated with human perception of the transition of the thermochromatic liquid crystal is eliminated by using a high speed digital camera and a computer. The method is validated by comparisons with results obtained by the steady-state method for a circular Jet impinging on a flat plate. Several factors affecting the accuracy of the method are evaluated.

Tan, Benjamin

1995-01-01

362

Atomization by jet impact  

Microsoft Academic Search

The formation and fragmentation of liquid sheets resulting from the oblique collision of two identical cylindrical jets is investigated. The liquid expands radially from the impacting point forming a sheet in the form of a bay leaf bounded by a thicker rim. The sheet shape, rim size and liquid velocity field are quantified and represented analytically. External harmonic perturbations of

N. Bremond; E. Villermaux

2006-01-01

363

A comparison of the pitching and plunging response of an oscillating airfoil  

NASA Technical Reports Server (NTRS)

An oscillating SC1095 airfoil model was tested for its aerodynamic stability in a rigid body with a single degree of freedom pitch about its quarter chord, and also in a rigid body with single degree of freedom plunge. The ability of pitching data to model plunging motions was evaluated. A one to one correspondence was established between pairs of pitching and plunging motions according to the potential flow transformation formula alpha=ikh. The imposed variables of the experiment were mean incidence angle, amplitude of motion, free stream velocity, and oscillatory frequency. Results indicate that significant differences exist between the aerodynamic responses to the motions, particularly at high load conditions. At high load conditions, the normal force for equivalent pitch is significantly greater than that for true pitch at the geometric incidence angle.

Carta, F. O.

1979-01-01

364

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

PubMed

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

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

2013-12-01

365

CFD based investigation on the impact acceleration when a gannet impacts with water during plunge diving.  

PubMed

Plunge diving is the most commonly used feeding method of a gannet, which can make the gannet transit from air to water rapidly and successfully. A large impact acceleration can be generated due to the air-to-water transition. However, the impact acceleration experienced by the gannet during plunge diving has not been studied. In this paper, this issue is investigated by using the CFD method. The effect of the dropping height and the water-entry inclination angle on the impact acceleration is considered. The results reveal that the impact acceleration along the longitudinal body axis increases with either of the two parameters. The peak time decreases with the dropping height. A quadratic relation is found between the peak impact acceleration and the initial water-entry velocity. According to the computation, when the dropping height is 30 m (most of gannets plunge from about this height), the peak impact acceleration can reach about 23 times the gravitational acceleration, which will exert a considerable force on the gannet body. Furthermore, the pressure distribution of different water-entry inclination angles indicates that the large pressure asymmetry caused by a small oblique angle may lead to a large impact acceleration in the direction perpendicular to the longitudinal body axis and cause damage to the neck of the gannet, which partly explains the reason why a gannet performing a high plunge diving in nature enters water with a large oblique angle from the perspective of impact mechanics. The investigation on the plunge-diving behavior in this paper will inspire and promote the development of a biomimetic amphibious robot that transits from air to water with the plunge-diving mode. PMID:23851321

Wang, T M; Yang, X B; Liang, J H; Yao, G C; Zhao, W D

2013-09-01

366

Jet impact on a soap film Geoffroy Kirstetter, Christophe Raufaste,  

E-print Network

Nice, France (Dated: August 28, 2012) We experimentally investigate the impact of a liquid jet of the micro-jet or con- versely on its destabilization through the control of the liquid jet atomization separated by liquid soap films. Their stability under mechanical solicitations is a major issue: as liquid

Paris-Sud XI, Université de

367

Jet Streams  

NSDL National Science Digital Library

This module describes the general characteristics of upper-level jet streams (Polar Jet, Subtropical Jet, and Tropical Easterly Jet) and two major tropical low-level wind maxima (Somali Jet, African Easterly Jet). Included are discussions of their formation, maintenance, influence on synoptic weather, and role in the general circulation.

Comet

2012-11-13

368

Particle-assisted dynamic wetting in a suspension liquid jet impinged onto a moving solid at dierent flow rates  

Microsoft Academic Search

We provide evidence that the introduction of solid spheres assists the dynamic wetting in suspension jet flows. The onset velocities of air entrainment in the suspension were measured and compared with those in the filler-free fluids to directly access the particle-assisted dynamic wetting. The measured onset velocity increased with increasing the particle contents at Re <20 where the dynamic contact

Masato Yamamura; Atsushi Matsunaga; Yoshihide Mawatari; Kitaro Adachi; Hiroyuki Kage

369

Parameter dependence of vortex interactions on a two-dimensional plunging plate  

NASA Astrophysics Data System (ADS)

The structure and dynamics of the flow field created by a plunging flat-plate airfoil are investigated at a chord Reynolds number of 10,000 while varying plunge amplitude and Strouhal number. Digital particle image velocimetry measurements are used to characterize the shedding patterns and the interactions between the leading- and trailing-edge vortex structures (LEV and TEV), resulting in the development of a wake classification system based on the nature and timing of interactions between the leading- and trailing-edge vortices. The streamwise advancement of the LEV during a plunge cycle and its resulting interaction with the TEV is primarily dependent on reduced frequency; however, for Strouhal numbers above approximately 0.4, significant changes are observed in the formation of vortices shed from the leading and trailing edges, as well as the circulation of the leading-edge vortex. The functional form of the relationship between leading-edge vortex circulation and Strouhal number suggests that the Strouhal number dependence is more specifically a manifestation of the effective angle of attack. Comparison with low-Reynolds-number studies of plunging airfoil aerodynamics reveals a high degree of consistency and suggests applicability of the classification system beyond the range examined in the present work.

Eslam Panah, Azar; Buchholz, James H. J.

2014-03-01

370

Motion Kinematics vs. Angle of Attack Effects in High-Frequency Airfoil Pitch/Plunge  

E-print Network

Motion Kinematics vs. Angle of Attack Effects in High-Frequency Airfoil Pitch/Plunge Michael V. OL1 10,000 with a SD7003 airfoil spanning the test section, while computations were with a 2D immersed loads time history and evolution of vortex shedding, especially at the airfoil leading edge. This turns

371

Use of bubble image velocimetry for measurement of plunging wave impinging on structure and associated greenwater  

Microsoft Academic Search

The measurement of velocity fields of a plunging wave impacting on a structure in a two-dimensional wave tank was investigated experimentally. As the wave impinged and overtopped the structure, a large highly aerated region was created in front of the structure and on top of the structure. The broken wave in front of the structure and associated greenwater on top

Yonguk Ryu; Kuang-An Chang; Ho-Joon Lim

2005-01-01

372

Turbulence transport, vorticity dynamics, and solute mixing under plunging breaking waves in surf zone  

Microsoft Academic Search

Plunging breaking waves generate turbulence and vorticity, which are of great importance for the solute and sediment transport in surf zone. In this paper the complex breaking processes are simulated by using an accurate numerical model that solves the Reynolds equations for the mean flow and modified k-? equations for the turbulence field. A solute transport model is employed to

Pengzhi Lin; Philip L.-F. Liu

1998-01-01

373

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

NASA Astrophysics Data System (ADS)

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

Lallave Cortes, Jorge C.

374

Twin Jet  

NASA Technical Reports Server (NTRS)

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

Henderson, Brenda; Bozak, Rick

2010-01-01

375

Mass exchange in gas desorption from finely dispersed liquid particles in an a near-wall two-phase jet  

SciTech Connect

This work deals with the experimental investigation of the mass exchange between finely dispersed liquid particles and a gas flow. We investigate mass transfer in the desorption process of a slightly water-soluble carbonic acid gas from the liquid particle surface at wide variations of the rate parameters for both gas and liquid phase. These data may be further used in the analysis of heat and mass transfer processes in near-wall two-phase flows.

Lebedev, V.P.; Terekhov, V.I.; Shishkin, N.E. [Institute of Thermophysics, Novosibirsk (Russian Federation)

1995-11-01

376

Jets and rotary flows for single-phase liquid cooling: An overview of some recent experimental findings  

Microsoft Academic Search

Single-phase liquid cooling is increasingly being deployed to cool high power, high heat flux electronic components such as microprocessors. In a conventional liquid cooling loop, the primary heat exchanger represents a key design challenge as this is typically subject to stringent constraints on footprint area and profile. This paper presents some experimental findings for two classes of flows of relevance

R. Grimes; N. Jeffers; D. Kearney

2010-01-01

377

Particle-assisted dynamic wetting in a suspension liquid jet impinged onto a moving solid at different flow rates  

Microsoft Academic Search

We provide evidence that the introduction of solid spheres assists the dynamic wetting in suspension jet flows. The onset velocities of air entrainment in the suspension were measured and compared with those in the filler-free fluids to directly access the particle-assisted dynamic wetting. The measured onset velocity increased with increasing the particle contents at Re20 where the dynamic contact line

Masato Yamamura; Atsushi Matsunaga; Yoshihide Mawatari; Kitaro Adachi; Hiroyuki Kage

2006-01-01

378

Liquid Impact Simulator.  

National Technical Information Service (NTIS)

The liquid impact simulator is capable of shooting single jets of water of diameters varying from .020 inch to .100 inch at speeds up to 3000 feet per second. Minor adaptations of the apparatus could produce even higher velocity jets. These liquid jets ar...

M. P. Scher

1966-01-01

379

Deposit formation in liquid fuels. II - The effect of selected compounds on the storage stability of Jet A turbine fuel  

NASA Technical Reports Server (NTRS)

The influence of substituted pyridines, pyrroles, indoles, and quinolines on the storage stability of conventional Jet A turbine fuel is evaluated. Significant increases in the amount of deposit formed in accelerated storage tests are found upon addition of these compounds at levels as low as one ppm nitrogen. While the effect is correlated with basicity of the nitrogen compound within a given compound class, the correlation does not hold between classes (pyridines, quinolines, etc.). Steric hindrance at the nitrogen atom greatly inhibits deposit promotion. The characteristics, but not the elemental composition, of deposits vary with the identity of the added nitrogen compound and with deposition temperature.

Worstell, J. H.; Daniel, S. R.

1981-01-01

380

Viscoelasticity breaks the symmetry of impacting jets.  

PubMed

A jet of a Newtonian liquid impacting on a wall at right angle spreads as a thin liquid sheet which preserves the radial symmetry of the jet. We report that for a viscoelastic jet (solution of polyethylene glycol in water) this symmetry can break; close to the wall, the jet cross section becomes faceted and radial steady liquid films (wings) form, which connect the cross-section vertices to the sheet. The number of wings increases with increasing the viscoelastic relaxation time of the solution, but also with increasing jet velocity and decreasing distance from the jet nozzle to the wall. We propose a mechanism for this surprising destabilization of the jet shape, which develops perpendicularly to the direction expected for a buckling mechanism, and explain these dependencies. We also discuss the large-scale consequences of the jet destabilization on the sheet spreading and fragmentation, which show through the faceting of hydraulic jumps and of suspended (Savart) sheets. PMID:25415909

Lhuissier, H; Néel, B; Limat, L

2014-11-01

381

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

USGS Publications Warehouse

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, K.A.; John, B.E.

1997-01-01

382

Analysis of a Free Surface Film from a Controlled Liquid Impinging Jet over a Rotating Disk Including Conjugate Effects, with and without Evaporation  

NASA Technical Reports Server (NTRS)

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 15 1pm with rotational speeds between 50 and 200 rpm are analyzed. The effects of inlet temperature on the film thickness and heat transfer are characterized as well as evaporative effects. The conjugate heating effect is modeled, and was found to effect the heat transfer results the most at both the inner and outer edges of the heated surface. The heat transfer was enhanced with both increasing flow rate and increasing rotational speeds. When evaporative effects were modeled, the evaporation was found to increase the heat transfer at the lower flow rates the most because of a fully developed thermal field that was achieved. The evaporative effects did not significantly enhance the heat transfer at the higher flow rates.

Sankaran, Subramanian (Technical Monitor); Rice, Jeremy; Faghri, Amir; Cetegen, Baki M.

2005-01-01

383

Thermal Tolerance Limits of Diamondback Moth in Ramping and Plunging Assays  

PubMed Central

Thermal sensitivity is a crucial determinant of insect abundance and distribution. The way it is measured can have a critical influence on the conclusions made. Diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) is an important insect pest of cruciferous crops around the world and the thermal responses of polyphagous species are critical to understand the influences of a rapidly changing climate on their distribution and abundance. Experiments were carried out to the lethal temperature limits (ULT0 and LLT0: temperatures where there is no survival) as well as Upper and Lower Lethal Temperature (ULT25 and LLT25) (temperature where 25% DBM survived) of lab-reared adult DBM population to extreme temperatures attained by either two-way ramping (ramping temperatures from baseline to LT25 and ramping back again) or sudden plunging method. In this study the ULT0 for DBM was recorded as 42.6°C and LLT0 was recorded as ?16.5°C. DBM had an ULT25 of 41.8°C and LLT25 of ?15.2°C. The duration of exposure to extreme temperatures had significant impacts on survival of DBM, with extreme temperatures and/or longer durations contributing to higher lethality. Comparing the two-way ramping temperature treatment to that of direct plunging temperature treatment, our study clearly demonstrated that DBM was more tolerant to temperature in the two-way ramping assay than that of the plunging assay for cold temperatures, but at warmer temperatures survival exhibited no differences between ramping and plunging. These results suggest that DBM will not be put under physiological stress from a rapidly changing climate, rather access to host plants in marginal habitats has enabled them to expand their distribution. Two-way temperature ramping enhances survival of DBM at cold temperatures, and this needs to be examined across a range of taxa and life stages to determine if enhanced survival is widespread incorporating a ramping recovery method. PMID:24475303

Nguyen, Chi; Bahar, Md Habibullah; Baker, Greg; Andrew, Nigel R.

2014-01-01

384

The effect of plunge electrodes during electrical stimulation of cardiac tissue  

Microsoft Academic Search

The mechanism for far-field stimulation of cardiac tissue is not known, although many hypotheses have been suggested. This paper explores a new hypothesis: the insulated plunge electrodes used in experiments to map the extracellular potential may affect the transmembrane potential when an electric field is applied to cardiac tissue. The authors' calculation simulates a 10-mm-diameter sheet of passive tissue with

Deborah M. Langrill; Bradley J. Roth

2001-01-01

385

Thermal tolerance limits of diamondback moth in ramping and plunging assays.  

PubMed

Thermal sensitivity is a crucial determinant of insect abundance and distribution. The way it is measured can have a critical influence on the conclusions made. Diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) is an important insect pest of cruciferous crops around the world and the thermal responses of polyphagous species are critical to understand the influences of a rapidly changing climate on their distribution and abundance. Experiments were carried out to the lethal temperature limits (ULT? and LLT?: temperatures where there is no survival) as well as Upper and Lower Lethal Temperature (ULT?? and LLT??) (temperature where 25% DBM survived) of lab-reared adult DBM population to extreme temperatures attained by either two-way ramping (ramping temperatures from baseline to LT?? and ramping back again) or sudden plunging method. In this study the ULT0 for DBM was recorded as 42.6°C and LLT? was recorded as -16.5°C. DBM had an ULT?? of 41.8°C and LLT25 of -15.2°C. The duration of exposure to extreme temperatures had significant impacts on survival of DBM, with extreme temperatures and/or longer durations contributing to higher lethality. Comparing the two-way ramping temperature treatment to that of direct plunging temperature treatment, our study clearly demonstrated that DBM was more tolerant to temperature in the two-way ramping assay than that of the plunging assay for cold temperatures, but at warmer temperatures survival exhibited no differences between ramping and plunging. These results suggest that DBM will not be put under physiological stress from a rapidly changing climate, rather access to host plants in marginal habitats has enabled them to expand their distribution. Two-way temperature ramping enhances survival of DBM at cold temperatures, and this needs to be examined across a range of taxa and life stages to determine if enhanced survival is widespread incorporating a ramping recovery method. PMID:24475303

Nguyen, Chi; Bahar, Md Habibullah; Baker, Greg; Andrew, Nigel R

2014-01-01

386

Jet pump assisted artery  

NASA Technical Reports Server (NTRS)

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

1975-01-01

387

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

PubMed

Range-time-frequency distributions of surf-generated noise were measured within the surf zone during the SandyDuck'97 experiment at Duck, NC. A 24-phone, 138-m, bottom-mounted, linear array located along a line perpendicular to the shore at a depth of 1 to 3 m recorded the surf-generated noise. Concurrent video measurements of the location, size, and time-evolution of the individual breaking waves directly above the array were made from a nearby 43-m tower. Source level spectra are obtained by using a modified fast field program to account for water column and geoacoustic propagation from the distributed source region to an individual hydrophone. The length, location, and orientation of the leading edge of breakers are tracked in time from rectified video images. It is observed that the source levels from spilling breakers are lower (approximately 5-10 dB) than those produced by plunging breakers that occurred during the same time period. Plunging breakers generated time-frequency signatures with a sharp onset while spilling breakers' signatures had a gradual low-frequency precursor. Range-time signatures of plunging breakers indicate a burst of acoustic energy while spilling breakers' signatures depict sound being generated over a longer time period with the source region moving with the breaking surface wave. PMID:12186029

Means, Steven L; Heitmeyer, Richard M

2002-08-01

388

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

PubMed Central

Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a need to determine optimum dimensioning values and hydraulic parameters. The aim of this work is to study the behaviour and performance of two species with different ecological characteristics (Iberian barbel Luciobarbus bocagei–bottom oriented, and Iberian chub Squalius pyrenaicus–water column) in a full-scale experimental pool-type fishway that offers two different flow regimes–plunging and streaming. Results showed that both species passed through the surface notch more readily during streaming flow than during plunging flow. The surface oriented species used the surface notch more readily in streaming flow, and both species were more successful in moving upstream in streaming flow than in plunging flow. Streaming flow enhances upstream movement of both species, and seems the most suitable for fishways in river systems where a wide range of fish morpho-ecological traits are found. PMID:23741465

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

2013-01-01

389

Jet injection into polyacrylamide gels: investigation of jet injection mechanics.  

PubMed

Jet injectors employ high-velocity liquid jets that penetrate into human skin and deposit drugs in the dermal or subdermal region. Although jet injectors have been marketed for a number of years, relatively little is known about the interactions of high-speed jets with soft materials such as skin. Using polyacrylamide gels as a model system, the mechanics of jet penetration, including the dependence of jet penetration on mechanical properties, was studied. Jets employed in a typical commercial injector, (orifice diameter: 152 microm, velocity: 170-180 m/s) were used to inject fluid into polyacrylamide gels possessing Young's moduli in the range of 0.06-0.77 MPa and hardness values in the range of 4-70 H(OO). Motion analysis of jet entry into polyacrylamide gels revealed that jet penetration can be divided into three distinct events: erosion, stagnation, and dispersion. During the erosion phase, the jet removed the gel at the impact site and led to the formation of a distinct cylindrical hole. Cessation of erosion induced a period of jet stagnation ( approximately 600 micros) characterized by constant penetration depth. This stage was followed by dispersion of the liquid into the gel. The dispersion took place by crack propagation and was nearly symmetrical with the exception of injections into 10% acrylamide (Young's modulus of 0.06 MPa). The penetration depth of the jets as well as the rate of erosion decreased with increasing Young's modulus. The mechanics of jet penetration into polyacrylamide gels provides an important tool for understanding jet injection into skin. PMID:15212923

Schramm-Baxter, Joy; Katrencik, Jeffrey; Mitragotri, Samir

2004-08-01

390

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

Microsoft Academic Search

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

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

2009-01-01

391

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

392

Estimation of the velocity field induced by plunging breakers in the surf and swash zones  

NASA Astrophysics Data System (ADS)

This study presents an investigation into the spatial and temporal evolution of the velocity field induced by plunging waves using the bubble image velocimetry (BIV) technique. The BIV velocity estimates are validated with both direct single-point measurements and a well-validated VOF-type numerical model. Firstly, BIV-derived time series of horizontal velocities are compared with single-point measurements, showing good agreement at two cross-shore locations on the impermeable slope in the swash and surf zones. The comparison includes a discussion on the uncertainty associated with both data sets. In order to evaluate the transient two-dimensional description of the flow field, a high-resolution VOF-type numerical model based on the Reynolds-averaged Navier-Stokes equations is used. A reliable estimation of the numerically derived surf zone velocity is established. In the swash zone, however, an overprediction of the offshore flow is identified, which may be ascribed to the single-phase nature of the numerical description, suggesting the importance of the dynamics of the air/water mixture for accurate modelling of this breaker type. The non-intrusive BIV technique was shown to be a good complementary tool to the numerical model in the estimation of velocity field induced by plunging waves in the laboratory. It is shown that the BIV technique is more suitable when the nature of the velocity field under the presence of an aerated flow is sought. This is relevant for hydrodynamic studies of plunging breakers when, due to air entrainment, the use of other measurement techniques or single-phase formulations in numerical models may provide uncertain results.

Rivillas-Ospina, Germán; Pedrozo-Acuña, Adrián; Silva, Rodolfo; Torres-Freyermuth, Alec; Gutierrez, César

2012-01-01

393

Free swimming of an elastic plate plunging at low Reynolds number  

NASA Astrophysics Data System (ADS)

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

Yeh, Peter Derek; Alexeev, Alexander

2014-05-01

394

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

395

Small mass plunging into a Kerr black hole: Anatomy of the inspiral-merger-ringdown waveforms  

NASA Astrophysics Data System (ADS)

We numerically solve the Teukolsky equation in the time domain to obtain the gravitational-wave emission of a small mass inspiraling and plunging into the equatorial plane of a Kerr black hole. We account for the dissipation of orbital energy using the Teukolsky frequency-domain gravitational-wave fluxes for circular, equatorial orbits, down to the light-ring. We consider Kerr spins -0.99?q?0.99, and compute the inspiral-merger-ringdown (2,2), (2,1), (3,3), (3,2), (4,4), and (5,5) modes. We study the large-spin regime, and find a great simplicity in the merger waveforms, thanks to the extremely circular character of the plunging orbits. We also quantitatively examine the mixing of quasinormal modes during the ringdown, which induces complicated amplitude and frequency modulations in the waveforms. Finally, we explain how the study of small mass-ratio black-hole binaries helps extending effective-one-body models for comparable-mass, spinning black-hole binaries to any mass ratio and spin magnitude.

Taracchini, Andrea; Buonanno, Alessandra; Khanna, Gaurav; Hughes, Scott A.

2014-10-01

396

Small mass plunging into a Kerr black hole: Anatomy of the inspiral-merger-ringdown waveforms  

E-print Network

We numerically solve the Teukolsky equation in the time domain to obtain the gravitational-wave emission of a small mass inspiraling and plunging into the equatorial plane of a Kerr black hole. We account for the dissipation of orbital energy using the Teukolsky frequency-domain gravitational-wave fluxes for circular, equatorial orbits, down to the light-ring. We consider Kerr spins $-0.99 \\leq q \\leq 0.99$, and compute the inspiral-merger-ringdown (2,2), (2,1), (3,3), (3,2), (4,4), and (5,5) modes. We study the large-spin regime, and find a great simplicity in the merger waveforms, thanks to the extremely circular character of the plunging orbits. We also quantitatively examine the mixing of quasinormal modes during the ringdown, which induces complicated amplitude and frequency modulations in the waveforms. Finally, we explain how the study of small mass-ratio black-hole binaries helps extending effective-one-body models for comparable-mass, spinning black-hole binaries to any mass ratio and spin magnitude.

Taracchini, Andrea; Khanna, Gaurav; Hughes, Scott A

2014-01-01

397

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

E-print Network

We study the transition from inspiral to plunge in general relativity by computing gravitational waveforms of non-spinning, equal-mass black-hole binaries. We consider three sequences of simulations, starting with a quasi-circular 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. We find that the motion transitions from inspiral to plunge when the orbital angular momentum L=L_crit is about 0.8M^2. For L

U. Sperhake; E. Berti; V. Cardoso; J. A. Gonzalez; B. Bruegmann; M. Ansorg

2007-10-21

398

Small mass plunging into a Kerr black hole: Anatomy of the inspiral-merger-ringdown waveforms  

E-print Network

We numerically solve the Teukolsky equation in the time domain to obtain the gravitational-wave emission of a small mass inspiraling and plunging into the equatorial plane of a Kerr black hole. We account for the dissipation of orbital energy using the Teukolsky frequency-domain gravitational-wave fluxes for circular, equatorial orbits, down to the light-ring. We consider Kerr spins $-0.99 \\leq q \\leq 0.99$, and compute the inspiral-merger-ringdown (2,2), (2,1), (3,3), (3,2), (4,4), and (5,5) modes. We study the large-spin regime, and find a great simplicity in the merger waveforms, thanks to the extremely circular character of the plunging orbits. We also quantitatively examine the mixing of quasinormal modes during the ringdown, which induces complicated amplitude and frequency modulations in the waveforms. Finally, we explain how the study of small mass-ratio black-hole binaries helps extending effective-one-body models for comparable-mass, spinning black-hole binaries to any mass ratio and spin magnitude.

Andrea Taracchini; Alessandra Buonanno; Gaurav Khanna; Scott A. Hughes

2014-04-07

399

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

E-print Network

We investigate the non-adiabatic 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 quasi-circular 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 of spin terms onto 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 40Hz and the frequency beyond which our analytical treatment becomes unreliable is found to be, when using the more reliable Effective One-Body dynamics: 0.6% M for anti-aligned maximally spinning black holes, 5% M for aligned maximally spinning black hole, and 1.8% M for non-spinning configurations. In confirmation of previous results, we find that, for all binaries considered, the dimensionless rotation parameter J/E^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 quasi-normal mode ringdown 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.

Alessandra Buonanno; Yanbei Chen; Thibault Damour

2005-08-16

400

Effect of flexibility of wing on aerodynamic performance in plunge motion  

NASA Astrophysics Data System (ADS)

The improvement of aerodynamic performance in plunge motion is investigated through a flexibility of chordwise and spanwise directions by applied a prescribed deformation on a airfoil at Reynolds number of 30000. The aerodynamic performance of flapping motion can be evaluated through a thrust force, a input power and a propulsive efficiency which is a ratio of propulsive power which generate from thrust force to input power. Unsteady viscous flows over NACA 0012 airfoils in plunge motions are computed by using a time-accurate preconditioned Navier-Stokes solver coupled with a volume grid deformation code. For spanwise or chordwise flexibility, there is a optimal phase angle for maximum thrust force and propulsive efficiency. Especially, a combination of spanwise and chordwise flexibility can improve aerodynamic performance higher than that of adding increment from each of flexibility. Compared with rigid motion, 10% deformation in chordwise and spanwise directions with zero phase angle can enhance the thrust force coefficient from 0.22 to 0.38 and 0.54 respectively, while thrust force coefficient is 0.8 by combination of spanwise and chordwise flexibility.

Le, Tuyen Quang; Ko, Jin Hwan; Park, Soo Hyung; Byun, Doyoung

2009-11-01

401

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

E-print Network

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 timescale 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.

Pranesh A. Sundararajan

2008-03-31

402

Stable Jets of Viscoelastic Fluids and Self-Assembled Cylindrical Capsules by Hydrodynamic Focusing  

E-print Network

, the aqueous phase forms jets that are 4-90 µm in diameter and several centimeters long. The liquid surfaces that hydrodynamic confinement can dramatically slow the break-up of liquid jets when the radius of the jetStable Jets of Viscoelastic Fluids and Self-Assembled Cylindrical Capsules by Hydrodynamic Focusing

Rothstein, Jonathan

403

36th AIAA Fluid Dynamics Conference and Exhibit, San Francisco, CA, Jun. 58, 2006 Trailing-Edge Flow about Unstalled Plunging Airfoil  

E-print Network

-Edge Flow about Unstalled Plunging Airfoil Computed by Euler Method Shuchi Yang , Shijun Luo , Feng Liu The flow around the trailing edge of a sinusoidally plunging NACA 0012 airfoil at zero mean angle of attack and moments of a flapping flat-plate airfoil for small perturbed inviscid and incompressible flow

Liu, Feng

404

Mean velocity and turbulence characteristics of water flow in the bubble dispersion region induced by plunging water jet  

Microsoft Academic Search

Water was injected vertically downward through a straight circular pipe onto a water bath contained in a cylindrical vessel. Three types of bubble dispersion patterns were observed with respect to the distance from the pipe exit to the undisturbed bath surface. When the distance was short, small bubbles were generated at the bath surface and they dispersed in the whole

M. Iguchi; K. Okita; F. Yamamoto

1998-01-01

405

Water Jetting  

NASA Technical Reports Server (NTRS)

Hi-Tech Inc., a company which manufactures water jetting equipment, needed a high pressure rotating swivel, but found that available hardware for the system was unsatisfactory. They were assisted by Marshall, which had developed water jetting technology to clean the Space Shuttles. The result was a completely automatic water jetting system which cuts rock and granite and removes concrete. Labor costs have been reduced; dust is suppressed and production has been increased.

1985-01-01

406

50 Ka Till-Filled Pleistocene Plunge Pools and Potholes Found Beneath the World Trade Center Site, New York, NY  

E-print Network

50 Ka Till-Filled Pleistocene Plunge Pools and Potholes Found Beneath the World Trade Center Site, explored the feature further, identifying additional till filled depressions (Moss and Merguerian, 2008 in greater detail and wood found buried in the till was 14 C dated. Figure 1 ­ World Trade Center site

Merguerian, Charles

407

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

PubMed

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. PMID:22874749

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

2012-10-22

408

An elastic mounting system for a wing providing continuously non-linear responses in pitch and plunge  

E-print Network

A device was built that provides smooth non-linear restoring forces and moments to the pitch and plunge of a wing in a wind tunnel. The device uses an innovative combination of cams and linear extension springs to produce the restoring forces which...

Barnett, Walter Joseph

2012-06-07

409

Characteristic length scales for vortex detachment on plunging profiles with varying leading-edge geometry  

NASA Astrophysics Data System (ADS)

Experiments on leading-edge vortex (LEV) growth and detachment from a plunging profile have been conducted in a free-surface water tunnel. Direct-force and velocity-field measurements have been performed at a Reynolds number of Re = 10,000, a reduced frequency of k = 0.25, and a Strouhal number of St = 0.16, for three varying leading-edge geometries. The leading-edge shape is shown to influence the shear layer feeding the LEV, and thus to some extent the development of the LEV and associated flow topology. This effect in turn influences the arrival time of the rear (LEV) stagnation point at the trailing edge, which, once breached, constitutes a detachment of the LEV. It is found that despite minor phase changes in LEV detachment through leading-edge shape, the position of the trailing edge (chord length) should be chosen as the characteristic length scale for the vortex separation process.

Rival, David E.; Kriegseis, Jochen; Schaub, Pascal; Widmann, Alexander; Tropea, Cameron

2014-01-01

410

Axial jet mixing of ethanol in cylindrical containers during weightlessness  

NASA Technical Reports Server (NTRS)

An experimental program was conducted to examine the liquid flow patterns that result from the axial jet mixing of ethanol in 10-centimeter-diameter cylindrical tanks in weightlessness. A convex hemispherically ended tank and two Centaur liquid-hydrogen-tank models were used for the study. Four distinct liquid flow patterns were observed to be a function of the tank geometry, the liquid-jet velocity, the volume of liquid in the tank, and the location of the tube from which the liquid jet exited.

Aydelott, J. C.

1979-01-01

411

Jet impact on a soap film  

E-print Network

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 refraction-like 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 flow in which the jet undulates along the film with a characteristic wavelength. Besides its fundamental interest, this study presents a new way to guide a micro-metric flow of liquid in the inertial regime and to probe foam stability submitted to violent perturbations at the soap film scale.

Geoffroy Kirstetter; Christophe Raufaste; Franck Celestini

2012-03-05

412

Jet impact on a soap film.  

PubMed

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

Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

2012-09-01

413

Vortex diode jet performance and theory  

SciTech Connect

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

Houck, E.D.

1993-12-01

414

Liquid Hydrogen  

Microsoft Academic Search

THE letter of W. Hampson, which appears in your issue of May 26, can only mean by implication to charge me with having utilised without acknowledgment an idea of his, conveyed through a third party, in my paper on the liquid hydrogen jet, published in 1895. Such a suggestion is absolutely without any foundation in fact. My results would have

J. Dewar

1898-01-01

415

Impact jetting by a solid sphere  

Microsoft Academic Search

We use a novel ultra-high-speed video camera to study the initial stage of the impact of a solid sphere onto a liquid surface, finding a high-speed horizontal jet which emerges immediately following the intial contact. For Re > 2 × 10(4) the jet emerges when the horizontal contact between the sphere and the liquid is only 12% of its diameter.

S. T. Thoroddsen; T. G. Etoh; K. Takehara; Y. Takano

2004-01-01

416

Mechanical probing of liquid foam aging  

E-print Network

We present experimental results on the Stokes experiment performed in a 3D dry liquid foam. The system is used as a rheometric tool : from the force exerted on a 1cm glass bead, plunged at controlled velocity in the foam in a quasi static regime, local foam properties are probed around the sphere. With this original and simple technique, we show the possibility of measuring the foam shear modulus, the gravity drainage rate and the evolution of the bubble size during coarsening.

Isabelle Cantat; Olivier Pitois

2006-09-19

417

An investigation into vortex growth and stabilization for two-dimensional plunging and flapping plates with varying sweep  

NASA Astrophysics Data System (ADS)

A simple analytical model for leading-edge vortex (LEV) growth is proposed and tested, based on the transport of vorticity-containing mass through the shear-layer. The two-dimensional case is validated using time-resolved Particle Image Velocimetry. As a precursor to developing a model for finite wings, the effect of varying spanwise flow on a nominally two-dimensional profile is investigated by imposing plunging and flapping motions on high aspect-ratio flat-plate profiles of sweep angles ?=+45°,-45° and 0°. By varying sweep angle, both coinciding and opposing gradients of spanwise vorticity stretching and convection were tested. It was shown that nominally two-dimensional spanwise flow has no effect on vortex strength and thus force history for plunging kinematics. However, force histories for flapping kinematics were dependent on sweep angle suggesting that spanwise flow regulates vortex strength when coupled with gradients in effective incidence.

Wong, Jaime G.; Kriegseis, Jochen; Rival, David E.

2013-11-01

418

Experimental investigation of the influence of the FSW plunge processing parameters on the maximum generated force and torque  

Microsoft Academic Search

The paper presents the results of an experimental investigation, done on the friction stir welding (FSW) plunging stage. Previous\\u000a research works showed that the axial force and torque generated during this stage were characteristic for a static qualification\\u000a of a FSW machine. Therefore, the investigation objectives are to better understand the relation between the processing parameters\\u000a and the forces and

Sandra Zimmer; Laurent Langlois; Julien Laye; Régis Bigot

2010-01-01

419

Distribution of Juvenile Bull Trout in a Thermal Gradient of a Plunge Pool in Granite Creek, Idaho  

Microsoft Academic Search

The distribution of juvenile bull trout Sal- velinus confluentus was observed on three nights (0000- 0200 hours) during July 24-28, 1992, in a large plunge pool in Granite Creek, a direct tributary to Lake Pend Orel lie in northern Idaho. The pool contained a strong side-to-side thermal gradient (8-15°C) created by the confluence of Granite Creek (water temperature 15°C) with

JOSEPH L. BONNEAU; DENNIS L. SCARNECCHIA

1996-01-01

420

THERMOELASTIC RESPONSE OF SUDDENLY HEATED LIQUID TARGETS IN HIGH-POWER COLLIDERS  

E-print Network

, are for a free liquid mercury jet heated by a 20- GeV proton beam, as described in work on the muon collider flow of the mercury jet was studied previously [4]. 2 LIQUID JET OSCILLATION A cylindrical jet. A liquid that is subjected to a strong negative pressure is known to be metastable. A main mechanism

Harilal, S. S.

421

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

422

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

423

Pursuit plunging by northern gannets (Sula bassana) feeding on capelin (Mallotus villosus).  

PubMed Central

Northern gannets (Sula bassana) are considered to obtain prey usually by rapid, vertical, shallow plunge dives. In order to test this contention and investigate underwater foraging behaviour, we attached two types of data-logging systems to 11 parental northern gannets at Funk Island in the North-Wiest Atlantic. We documented, for the first time to the authors' knowledge, gannets performing long, flat-bottomed, U-shaped dives that involved underwater wing propulsion as well as rapid, shallow, V-shaped dives. The median and maximum dive depths and durations were 4.6 and 22.0 m and 8 and 38 s, respectively. Short, shallow dives were usually V-shaped and dives deeper than 8 m and longer than 10 s were usually U-shaped, including a period at constant depth (varying between 4 and 28s with median 8s). Diving occurred throughout the daylight period and deepest dives were performed during late morning. On the basis of motion sensors in the loggers and food collections from telemetered birds, we concluded that extended, deep dives were directed at deep schools of capelin, a small pelagic fish, and we hypothesized that V-shaped dives were aimed at larger, pelagic fishes and squids. Furthermore, these V-shaped dives allowed the birds to surprise their pelagic prey and this may be critical because the maximum swimming speeds of the prey species may exceed the maximum dive speeds of the birds. PMID:12233767

Garthe, S; Benvenuti, S; Montevecchi, W A

2000-01-01

424

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

425

Dynamics of a jet in a coflowing soap film  

NASA Astrophysics Data System (ADS)

A liquid jet is introduced through a short tube in the plane of a vertically flowing soap film. The jet and the film have the same soap concentration and their speeds are independently adjustable. The wetting of the jet in the liquid film prevents the development of a Rayleigh instability. At low film speeds, the jet is straight. However, for every jet speed, there is a critical film speed, at which we observe a qualitative change in the dynamics: the jet assumes a sinuous form through an instability resembling that of a wake. This transition corresponds to either a global or a convective instability, depending on the jet speed. We document these transitions using high speed imaging and compare our results with existing theoretical analysis. At still higher film speeds, more complex behaviors, such as the separation of filaments from the main jet at wave crests, give rise to visually striking patterns. Our study captures some fundamental dynamics observed in coaxial injection.

Cone, Adam; Vandenberghe, Nicolas; Zhang, Jun

2004-11-01

426

Jet-induced skin puncture and its impact on needle-free jet injections: experimental studies and a predictive model.  

PubMed

Needle-free jet injections constitute an important method of drug delivery, especially for insulin and vaccines. This report addresses the mechanisms of interactions of liquid jets with skin. Liquid jets first puncture the skin to form a hole through which the fluid is deposited into skin. Experimental studies showed that the depth of the hole significantly affects drug delivery by jet injections. At a constant jet exit velocity and nozzle diameter, the hole depth increased with increasing jet volume up to an asymptotic value and decreased with increasing values of skin's uniaxial Young's modulus. A theoretical model was developed to predict the hole depth as a function of jet and skin properties. A simplified model was first verified with polyacrylamide gels, a soft material in which the fluid mechanics during hole formation is well understood. Prediction of the hole depth in the skin is a first step in quantitatively predicting drug delivery by jet injection. PMID:16002174

Baxter, Joy; Mitragotri, Samir

2005-09-01

427

Liquid sampling system  

DOEpatents

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

Larson, L.L.

1984-09-17

428

Liquid sampling system  

DOEpatents

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

Larson, Loren L. (Idaho Falls, ID)

1987-01-01

429

TEXTILE RESEARCH JOURNAL Effect of Nozzle Geometry on Hydroentangling Water Jets  

E-print Network

energy is lost and the jet disperses immediately. The breakup mechanism of nozzle water jets has been forces and initial disturbances) in the water jet, aerodynanic interaction effects, liquid turbu- lence] among others [4, 13, 18]. While no single mechanism alone can be held responsible for water-jet breakup

Tafreshi, Hooman Vahedi

430

Jet energy scale determination in the D0 experiment  

E-print Network

The calibration of jet energy measured in the \\DZero detector is presented, based on ppbar collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. Jet energies are measured using a sampling calorimeter composed of uranium and liquid argon as the passive and active media, respectively. This paper describes the energy calibration of jets performed with photon+jet, Z+jet and dijet{} events, with jet transverse momentum pT > 6 GeV and pseudorapidity range |eta| energy in simulation and in particular of the effects due to the flavor of the parton originating the jet, correcting biases up to 3%-4% in jets with low pT originating from gluons and up to 6%-8% in jets from b quarks.

D0 Collaboration

2013-12-24

431

Mixing at the external boundary of a submerged turbulent jet A. Eidelman,1,* T. Elperin,1,  

E-print Network

. It was found in 17 that mixing becomes more effective in a liquid jet for the larger Reynolds num- bers of Brownian molecular diffusion, and is the kinematic viscosity. For the liquid jets, Sc 102 , the improvedMixing at the external boundary of a submerged turbulent jet A. Eidelman,1,* T. Elperin,1, N

Elperin, Tov

432

Complex C: A Low-Metallicity, High-Velocity Cloud Plunging into the Milky Way  

NASA Astrophysics Data System (ADS)

We present evidence that high-velocity cloud (HVC) complex C is a low-metallicity gas cloud that is plunging toward the disk and beginning to interact with the ambient gas that surrounds the Milky Way. This evidence begins with a new high-resolution (7 km s-1 FWHM) echelle spectrum of 3C 351 obtained with the Space Telescope Imaging Spectrograph (STIS). 3C 351 lies behind the low-latitude edge of complex C, and the new spectrum provides accurate measurements of O I, Si II, Al II, Fe II, and Si III absorption lines at the velocity of complex C; N I, S II, Si IV, and C IV are not detected at 3 ? significance in complex C proper. However, Si IV and C IV as well as O I, Al II, Si II and Si III absorption lines are clearly present at somewhat higher velocities associated with a ``high-velocity ridge'' (HVR) of 21 cm emission. This high-velocity ridge has a similar morphology to and is roughly centered on complex C proper. The similarities of the absorption-line ratios in the HVR and complex C suggest that these structures are intimately related. In complex C proper we find [O/H]=-0.76+0.23-0.21. For other species the measured column densities indicate that ionization corrections are important. We use collisional and photoionization models to derive ionization corrections; in both models we find that the overall metallicity Z=0.1-0.3 Zsolar in complex C proper, but nitrogen must be underabundant. The iron abundance indicates that the complex C contains very little dust. The size and density implied by the ionization models indicate that the absorbing gas is not gravitationally confined. The gas could be pressure confined by an external medium, but alternatively we may be viewing the leading edge of the HVC, which is ablating and dissipating as it plunges into the Milky Way. O VI column densities observed with the Far Ultraviolet Spectroscopic Explorer (FUSE) toward nine QSOs/AGNs behind complex C support this conclusion: N(O VI) is highest near 3C 351, and the O VI/H I ratio increases substantially with decreasing latitude, suggesting that the lower latitude portion of the cloud is interacting more vigorously with the Galaxy. The other sight lines through complex C show some dispersion in metallicity, but, with the current uncertainties, the measurements are consistent with a constant metallicity throughout the HVC. However, all of the complex C sight lines require significant nitrogen underabundances. Finally, we compare the 3C 351 data with high-resolution STIS observations of the nearby QSO H1821+643 to search for evidence of outflowing Galactic fountain gas that could be mixing with complex C. We find that the intermediate-velocity gas detected toward 3C 351 and H1821+643 has a higher metallicity and may well be a fountain/chimney outflow from the Perseus spiral arm. However, the results for the higher velocity gas are inconclusive: the HVC detected toward H1821+643 near the velocity of complex C could have a similar metallicity to the 3C 351 gas or it could have a significantly higher Z, depending on the poorly constrained ionization correction. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Tripp, Todd M.; Wakker, Bart P.; Jenkins, Edward B.; Bowers, C. W.; Danks, A. C.; Green, R. F.; Heap, S. R.; Joseph, C. L.; Kaiser, M. E.; Linsky, J. L.; Woodgate, B. E.

2003-06-01

433

Complex C: A Low-Metallicity High-Velocity Cloud Plunging into the Milky Way  

E-print Network

(Abridged) We present a new high-resolution (7 km/s FWHM) echelle spectrum of 3C 351 obtained with STIS. 3C 351 lies behind the low-latitude edge of high-velocity cloud Complex C, and the new spectrum provides accurate measurements of O I, Si II, Al II, Fe II, and Si III absorption lines at the velocity of the HVC. We use collisional and photoionization models to derive ionization corrections; in both models we find that the overall metallicity Z = 0.1 - 0.3 Z_{solar} in Complex C, but nitrogen must be underabundant. The iron abundance indicates that Complex C contains very little dust. The absorbing gas probably is not gravitationally confined. The gas could be pressure-confined by an external medium, but alternatively we may be viewing the leading edge of the HVC, which is ablating and dissipating as it plunges into the Milky Way. O VI column densities observed with FUSE toward nine QSOs/AGNs behind Complex C support this conclusion: N(O VI) is highest near 3C 351, and the O VI/H I ratio increases substantially with decreasing latitude, suggesting that the lower-latitude portion of the cloud is interacting more vigorously with the Galaxy. The other sight lines through Complex C show some dispersion in metallicity, but with the current uncertainties, the measurements are consistent with a constant metallicity throughout the HVC. However, all of the Complex C sight lines require significant nitrogen underabundances. Finally, we compare the 3C 351 sight line to the sight line to the nearby QSO H1821+643 to search for evidence of outflowing Galactic fountain gas that could be mixing with Complex C. We find that the intermediate-velocity gas detected toward 3C 351 and H1821+643 has a higher metallicity and may well be a fountain/chimney outflow from the Perseus spiral arm.

T. M. Tripp; B. P. Wakker; E. B. Jenkins; C. W. Bowers; A. C. Danks; R. F. Green; S. R. Heap; C. L. Joseph; M. E. Kaiser; J. L. Linsky; B. E. Woodgate

2003-02-25

434

Laser ablation of liquid surface in air induced by laser irradiation through liquid medium  

Microsoft Academic Search

The pulse laser ablation of a liquid surface in air when induced by laser irradiation through a liquid medium has been experimentally\\u000a investigated. A supersonic liquid jet is observed at the liquid–air interface. The liquid surface layer is driven by a plasma\\u000a plume that is produced by laser ablation at the layer, resulting in a liquid jet. This phenomenon occurs only

Yuji Utsunomiya; Takashi Kajiwara; Takashi Nishiyama; Kunihito Nagayama; Shiro Kubota; Motonao Nakahara

2010-01-01

435

Experimental study of elliptical jet from sub to supercritical conditions  

NASA Astrophysics Data System (ADS)

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

Muthukumaran, C. K.; Vaidyanathan, Aravind

2014-04-01

436

Separation Of Liquid And Gas In Zero Gravity  

NASA Technical Reports Server (NTRS)

Pair of reports describe scheme for separating liquid from gas so liquid could be pumped. Designed to operate in absence of gravitation. Jet of liquid, gas, or liquid/gas mixture fed circumferentially into cylindrical tank filled with liquid/gas mixture. Jet starts liquid swirling. Swirling motion centrifugally separates liquid from gas. Liquid then pumped from tank at point approximately diametrically opposite point of injection of jet. Vortex phase separator replaces such devices as bladders and screens. Requires no components inside tank. Pumps for gas and liquid outside tank and easily accessible for maintenance and repairs.

Howard, Frank S.; Fraser, Wilson S.

1991-01-01

437

Impinging jets atomization  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

438

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS  

SciTech Connect

By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A., E-mail: ron.moore@nasa.go [Space Science Office, VP62, Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2010-09-01

439

Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets  

NASA Technical Reports Server (NTRS)

By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T 10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Moore, R. L.; Cirtain, J. W.; Sterling, A. C.; Falconer, D. A.

2010-01-01

440

Jets from compact objects  

E-print Network

Some topics in the theory of jets are reviewed. These include jet precession, unconfined jets, the origin of knots, the internal shock model as a unifying theme from protostellar jets to Gamma-ray bursts, relations between the Blandford-Znajek and MHD disk-wind models, and jet collimation in magnetic acceleration models.

H. C. Spruit

2000-03-03

441

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

442

The motion of a falling liquid filament Diane Hendersona)  

E-print Network

The motion of a falling liquid filament Diane Hendersona) William G. Pritchard Fluid Mechanics points. A nearby but different problem, on the stability of a uniform liquid jet, was studied long ago, because a uni- form liquid jet and a falling liquid filament are different. This can be seen in at least

Smolka, Linda B.

443

Shock-wave-induced jetting of micron-size bubbles.  

PubMed

Free gas bubbles in water with radii between 7 and 55 microm subjected to a shock wave exhibit a liquid jetting phenomenon with the jet pointing in the direction of the propagating shock wave. With increasing bubble radius, the length of the jet tip increases and a lower estimate of the averaged jet velocity increases linearly from 20 to 150 m/s. At a later stage, the jet breaks up and releases micron-size bubbles. In the course of shock wave permeabilization and transfection of biological cells, this observation suggests a microinjection mechanism when the cells are near bubbles exposed to a shock wave. PMID:12786557

Ohl, C D; Ikink, R

2003-05-30

444

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

445

Global Three-Dimensional Simulations of Black Hole Accretion Disks: X-ray Flares in the Plunging Region  

E-print Network

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. 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 the angular momentum. We found that in the innermost plunging region, non-axisymmetric 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 which subsequently are stretched and amplified due to differential rotation, current density increases inside the channel. Magnetic reconnection taking place in the current sheet produces slow mode shock waves which propagate away from the reconnection site. Magnetic energy release in the innermost plunging region can 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.

Mami Machida; Ryoji Matsumoto

2002-11-12

446

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

Microsoft Academic Search

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

Avram Bar-Cohen; Mehmet Arik; Michael Ohadi

447

Short communications Experiments in Fluids 27 (1999) 102--106 Springer-Verlag 1999 Visualization of high-speed gas jets and their airblast sprays  

E-print Network

of high-speed gas jets and their airblast sprays of cross-injected liquid K. D. Kihm, T. K. Kim, S. Y. Son. For the visualization of high-speed gas jets (with no liquid injected), Nd:YAG pulsed laser sheets imaged the clustered a jet with a higher Mach number than the former. It is conjectured that the injected liquid interactions

Kihm, IconKenneth David

448

Spray formation processes of impinging jet injectors  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

449

AEA Fluidic Pulse Jet Mixer. Innovative Technology Summary Report  

SciTech Connect

AEA's Fluidic Pulse Jet Mixer was developed to mix and maintain the suspension of solids and to blend process liquids. The mixer can be used to combine a tank's available supernate with the sludge into a slurry that is suitable for pumping. The system uses jet nozzles in the tank coupled to a charge vessel. Then, a jet pump creates a partial vacuum in the charge vessel allowing it to be filled with waste. Next, air pressure is applied to the charge vessel, forcing sludge back into the tank and mixing it with the liquid waste. When the liquid waste contains 10% solids, a batch is pumped out of the tank.

None

1999-08-01

450

ILASS Americas, 21th Annual Conference on Liquid Atomization and Spray Systems, Orlando, Florida, May18-2, 2008  

E-print Network

, May18-2, 2008 Influence of a Coaxial Gas Flow on a Flashing Liquid Jet: Implications for Flame Spray breakup of a liquid jet occurs when a pressurized subcooled or saturated liquid is released to a lower). Traditional op- eration of the spray burner requires atomization of a liquid precursor jet by a coaxial gas

Aguilar, Guillermo

451

Making black holes visible: accretion, radiation, and jets  

E-print Network

With the fundamental stress mechanism of accretion disks identified--correlated MHD turbulence driven by the magneto-rotational instability--it has become possible to make numerical simulations of accretion disk dynamics based on well-understood physics. A sampling of results from both Newtonian 3-d shearing box and general relativistic global disk MHD simulations is reported. Among other things, these simulations have shown that: contrary to long-held assumptions, stress is continuous through the marginally stable and plunging regions around black holes, so that rotating black holes can give substantial amounts of angular momentum electromagnetically to surrounding matter; the upper layers of accretion disks are primarily supported by magnetic pressure, potentially leading to interesting departures from local black-body emitted spectra; and initially local magnetic fields in accretion flows can, in some cases, spontaneously generate large-scale fields that connect rotating black holes to infinity and mediate strong relativistic jets.

J. H. Krolik

2007-09-10

452

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

453

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

454

Jet radiation radius  

NASA Astrophysics Data System (ADS)

Jet radiation patterns are indispensable for the purpose of discriminating partons with different quantum numbers. However, they are also vulnerable to various contaminations from the underlying event, pileup, and radiation of adjacent jets. In order to maximize the discrimination power, it is essential to optimize the jet radius used when analyzing the radiation patterns. We introduce the concept of jet radiation radius, which quantifies how the jet radiation is distributed around the jet axis. We study the color and momentum dependence of the jet radiation radius and discuss two applications: quark-gluon discrimination and W -jet tagging. In both cases, smaller (sub)jet radii are preferred for jets with higher pT's, albeit due to different mechanisms: the running of the QCD coupling constant and the boost to a color-singlet system. A shrinking cone W -jet tagging algorithm is proposed to achieve better discrimination than previous methods.

Han, Zhenyu

2014-10-01

455

Inclusive Jets in PHP  

E-print Network

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

Roloff, Philipp

2013-01-01

456

Inclusive Jets in PHP  

E-print Network

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

Philipp Roloff

2013-10-23

457

Inclusive Jets in PHP  

NASA Astrophysics Data System (ADS)

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

Roloff, P.

458

Jet Radiation Radius  

E-print Network

Jet radiation patterns are indispensable for the purpose of discriminating partons' with different quantum numbers. However, they are also vulnerable to various contaminations from the underlying event, pileup, and radiation of adjacent jets. In order to maximize the discrimination power, it is essential to optimize the jet radius used when analyzing the radiation patterns. We introduce the concept of jet radiation radius which quantifies how the jet radiation is distributed around the jet axes. We study the color and momentum dependence of the jet radiation radius, and discuss two applications: quark-gluon discrimination and $W$ jet tagging. In both cases, smaller (sub)jet radii are preferred for jets with higher PTs, albeit due to different mechanisms: the running of the QCD coupling constant and the boost to a color singlet system. A shrinking cone W jet tagging algorithm is proposed to achieve better discrimination than previous methods.

Zhenyu Han

2014-02-06

459

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

460

Deep penetration and liquid injection into adipose tissue Kerstyn Comley and Norman Fleck1  

E-print Network

) a needle or liquid jet penetrates the tissue to a desired depth (intradermal, subcutaneous, intramuscular). Subsequent delivery of the bulk of the liquid into the subcutaneous layer follows at a lower jet pressure tipped needle and a liquid jet penetrate a soft solid by the formation and opening of a planar crack

Fleck, Norman A.