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1

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

2

Distinguishing features of shallow angle plunging jets  

NASA Astrophysics Data System (ADS)

Numerical simulations employing an algebraic volume-of-fluid methodology are used to study the air entrainment characteristics of a water jet plunging into a quiescent water pool at angles ranging from ? = 10° to ? = 90° measured from the horizontal. Our previous study of shallow angled jets [S. S. Deshpande, M. F. Trujillo, X. Wu, and G. L. Chahine, "Computational and experimental characterization of a liquid jet plunging into a quiescent pool at shallow inclination," Int. J. Heat Fluid Flow 34, 1-14 (2012)], 10.1016/j.ijheatfluidflow.2012.01.011 revealed the existence of a clearly discernible frequency of ingestion of large air cavities. This is in contrast with chaotic entrainment of small air pockets reported in the literature in case of steeper or vertically plunging jets. In the present work, the differences are addressed by first quantifying the cavity size and entrained air volumes for different impingement angles. The results support the expected trend - reduction in cavity size (D43) as ? is increased. Time histories of cavity volumes in the vicinity of the impingement region confirm the visual observations pertaining to a near-periodic ingestion of large air volumes for shallow jets (10°, 12°), and also show that such cavities are not formed for steep or vertical jets. Each large cavity (defined as Dc/Dj ? 3) exists in close association with a stagnation point flow. A local mass and momentum balance shows that the high stagnation pressure causes a radial redirection of the jet, resulting in a flow that resembles the initial impact of a jet on the pool. In fact, for these large cavities, their speed matches closely Uimpact/2, which coincides with initial cavity propagation for sufficiently high Froude numbers. Furthermore, it is shown that the approximate periodicity of air entrainment scales linearly with Froude number. This finding is confirmed by a number of simulations at ? = 12°. Qualitatively, for steeper jets, such large stagnation pressure region does not exist, and the deflection of the entire incoming jet is non-existent. In fact, for ? = 25°, 45°, 90°, the jet penetrates the pool nearly undisturbed and consequently large cavities are not formed.

Deshpande, Suraj S.; Trujillo, Mario F.

2013-08-01

3

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

4

Bubble Entrainment and Dispersion in Plunging Jet Flows: Freshwater vs. Seawater  

Microsoft Academic Search

CHANSON, H.; AOKI, S., and HOQUE, A., 2006. Bubble entrainment and dispersion in plunging jet flows: freshwater vs. seawater. Journal of Coastal Research, 22(3), 664-677. West Palm Beach (Florida), ISSN 0749-0208. Air entrainment and bubble dispersion were studied systematically at vertical circular plunging jets in freshwater, saltwater, and seawater. Although the inception conditions for air entrainment are identical for all

H. Chanson; S. Aoki; A. Hoque

2006-01-01

5

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

6

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...

7

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

8

Determination of heat transfer coefficients in plastic French straws plunged in liquid nitrogen.  

PubMed

The knowledge of the thermodynamic process during the cooling of reproductive biological systems is important to assess and optimize the cryopreservation procedures. The time-temperature curve of a sample immersed in liquid nitrogen enables the calculation of cooling rates and helps to determine whether it is vitrified or undergoes phase change transition. When dealing with cryogenic liquids, the temperature difference between the solid and the sample is high enough to cause boiling of the liquid, and the sample can undergo different regimes such as film and/or nucleate pool boiling. In the present work, the surface heat transfer coefficients (h) for plastic French straws plunged in liquid nitrogen were determined using the measurement of time-temperature curves. When straws filled with ice were used the cooling curve showed an abrupt slope change which was attributed to the transition of film into nucleate pool boiling regime. The h value that fitted each stage of the cooling process was calculated using a numerical finite element program that solves the heat transfer partial differential equation under transient conditions. In the cooling process corresponding to film boiling regime, the h that best fitted experimental results was h=148.12±5.4W/m(2)K and for nucleate-boiling h=1355±51W/m(2)K. These values were further validated by predicting the time-temperature curve for French straws filled with a biological fluid system (bovine semen-extender) which undergoes freezing. Good agreement was obtained between the experimental and predicted temperature profiles, further confirming the accuracy of the h values previously determined for the ice-filled straw. These coefficients were corroborated using literature correlations. The determination of the boiling regimes that govern the cooling process when plunging straws in liquid nitrogen constitutes an important issue when trying to optimize cryopreservation procedures. Furthermore, this information can lead to improvements in the design of cooling devices in the cryobiology field. PMID:25445573

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

2014-12-01

9

Atomization of a liquid jet  

Microsoft Academic Search

The jet atomization process has various applications, including liquid fuel injection in internal combustion engines, spray coatings of protective materials on surfaces, and sprays of pesticides. Here, the stability of a liquid jet issued into an ambient gas is investigated with respect to spatially growing disturbances. The results are used to explain the existence of the intact length, the formation

S. P. Lin; D. J. Kang

1987-01-01

10

Submerged liquid jet impingement cooling  

Microsoft Academic Search

In this paper, submerged liquid jet array impingement is proposed as a solution for the thermal management of the high performance electronics. Experiments were done using a submerged jet array of 285 nozzles of 0.5 mm diameter spaced 5.5 mm apart, machined on a 5 mm thick nozzle plate, with an impingement height of 3 mm. The temperature difference between

Z. Y. Wang; T. N. Wong; F. Duan; K. C. Toh; K. F. Choo; S. P. Tan; C. V. Loh; S. C. Yeo

2011-01-01

11

Atomization of a liquid jet  

NASA Astrophysics Data System (ADS)

The jet atomization process has various applications, including liquid fuel injection in internal combustion engines, spray coatings of protective materials on surfaces, and sprays of pesticides. Here, the stability of a liquid jet issued into an ambient gas is investigated with respect to spatially growing disturbances. The results are used to explain the existence of the intact length, the formation of the spray angle, and some aspects of the mechanism of atomization.

Lin, S. P.; Kang, D. J.

1987-07-01

12

Whipping of electrified liquid jets.  

PubMed

We apply an electric field to a moderately conducting liquid surrounded by another coflowing liquid, all inside a glass-based microfluidic device, to study nonaxisymmetric instabilities. We find that the bending of the electrified jet results in a steady-state, helicoidal structure with a constant opening angle. Remarkably, the characteristic phase speed of the helicoidal wave only depends on the charge carried by the jet in the helicoidal region and its stability critically depends on the properties of the coflowing liquid. In fact, the steady-state helical structure becomes chaotic when the longest characteristic time is that of the inner liquid rather than that of the outer coflowing liquid. We also perform a numerical analysis to show that the natural preference of the jet is to adopt the conical helix structure observed experimentally. PMID:25201984

Guerrero, Josefa; Rivero, Javier; Gundabala, Venkata R; Perez-Saborid, Miguel; Fernandez-Nieves, Alberto

2014-09-23

13

Disintegration of a Liquid Jet  

NASA Technical Reports Server (NTRS)

This report presents an experimental determination of the process of disintegration and atomization in its simplest form, and the influence of the physical properties of the liquid to be atomized on the disintegration of the jet. Particular attention was paid to the investigation of the process of atomization.

Haenlein, A

1932-01-01

14

Dynamics of liquid films and thin jets  

Microsoft Academic Search

The theory of liquid films and thin jets as one- and two-dimensional continuums is examined. The equations of motion have led to solutions for the characteristic speeds of wave propagation for the parameters characterizing the shape. The formal analogy with a compressible fluid indicates the possibility of shock wave generation in films and jets and the formal analogy to the

Michail Zak

1979-01-01

15

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

E-print Network

, where g is the acceleration due to gravity, is the liquid density and is the surface tension of water through a regulator and a flowmeter. All nozzles consisted of stainless steel needles with length was measured experimen- tally applying an edge finding filter to the average image resulting from 125 video

Clanet, Christophe

16

Mechanism of atomization of a liquid jet  

NASA Astrophysics Data System (ADS)

Models for the break-up of atomizing jets are examined analytically and compared with experimental data. Among the atomization models are dynamic interaction between the liquid and the gas leading to unstable wave growth on the liquid jet surface, liquid turbulence within the nozzle, a radial velocity component in turbulent pipe flow disrupting the jet at the nozzle exit, etc. Two spray chambers, one with a 19 cm i.d. for air and nitrogen and one with a 3.5 cm i.d. for xenon and helium flow, contained up to 40 cu cm of a test liquid under constant pressures. The liquids were driven by a piston through 0.34-0.39 mm exits, while monitoring by high speed photography and strobed flash photographs was performed. None of the previous models were found adequate for describing the observed atomized flows. Cavitation was found to be critical but not a sufficient factor for the onset of atomization.

Reitz, R. D.; Bracco, F. V.

1982-10-01

17

Capillary instability of elliptic liquid jets  

NASA Astrophysics Data System (ADS)

Instability of a liquid jet issuing from an elliptic nozzle in Rayleigh mode is investigated and its behavior is compared with a circular jet. Mathematical solution of viscous free-surface flow for asymmetric geometry is complicated if 3-D analytical solutions are to be obtained. Hence, one-dimensional Cosserat (directed curve) equations are used which can be assumed as a low order form of Navier-Stokes equations for slender jets. Linear solution is performed using perturbation method. Temporal dispersion equation is derived to find the most unstable wavelength responsible for the jet breakup. The obtained results for a circular jet (i.e., an ellipse with an aspect ratio of one) are compared with the classical results of Rayleigh and Weber for inviscid and viscous cases, respectively. It is shown that in the Rayleigh regime, which is the subject of this research, symmetric perturbations are unstable while asymmetric perturbations are stable. Consequently, spatial analysis is performed and the variation of growth rate under the effect of perturbation frequencies for various jet velocities is demonstrated. Results reveal that in comparison with a circular jet, the elliptic jet is more unstable. Furthermore, among liquid jets with elliptical cross sections, those with larger ellipticities have a larger instability growth rate.

Amini, Ghobad; Dolatabadi, Ali

2011-08-01

18

High-Speed Microscale Liquid Jets  

NASA Astrophysics Data System (ADS)

Microscale, high-speed evaporating liquid jets that are injected into a quiescent gaseous medium having variable ambient pressure are investigated using a shadowgraph technique. The jets are formed by micromachined, O(10 microns) silicon nozzles from a small-scale pressurized reservoir. The jet flow is visualized using a pulsed ND:Yag laser and imaged on a 12 bit CCD camera where the field of view measures 200 microns on the side. Velocity distributions are assessed from features of the shadowgraph images using standard correlation techniques. The effects of ambient pressure and evaporation on the near field evolution of the jet are investigated over a range of jet speeds with particular emphasis on column breakup and the formation of droplets.

Berg, John; Glezer, Ari

2004-11-01

19

Vorticity Evolution through Pinch off in Liquid/Liquid Jets  

NASA Astrophysics Data System (ADS)

The pinch-off process was examined in glycerin/water jets flowing into a nearly immiscible ambient of Dow Corning 200 fluid. The Reynolds number, Froude number, and Weber numbers based on the jet exit conditions were 34, 0.17, and 0.24 respectively, and the ratio of outer to inner viscosity was 5.7. The jet was forced to yield repeatable drop formation at the forcing frequency. Index matching and particle image velocimetry were employed to obtain full two-dimensional velocity and vorticity fields on both sides of the liquid/liquid interface. The evolving vorticity field reveals enhanced local vorticity as the pinch-off process begins. This rotation is associated with jet fluid rushing into the drop forming downstream. The enhanced vorticity decreases as the jet end necks down into a conical shape and the drop detaches. After pinch-off, the recoil of the jet end causes a ring of ‘inverted’ vorticity to develop. The inverted ring persists downstream of the jet end through approximately half of the drop formation cycle.

Gefroh, D. L.; Longmire, E. K.; Lowengrub, J. S.

1998-11-01

20

Plunging Ranula: A Case Report  

PubMed Central

Plunging ranulas, also known as deep, diving, cervical or deep plunging ranula, usually appear in conjunction with oral ranula. Rarely, these ranulas may arise independent of oral swelling. A rare case of plunging ranula without oral swelling is discussed along with review of literature. PMID:21991487

Gupta, Ambika; Karjodkar, F. R.

2011-01-01

21

Size limits the formation of liquid jets during bubble bursting  

PubMed Central

A bubble reaching an air–liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R?100??m. However, few studies have been devoted to small bubbles (R<100??m) despite the entrainment of a large number of such bubbles in sea water. Here we show that jet formation is inhibited by bubble size; a jet is not formed during bursting for bubbles smaller than a critical size. Using ultrafast X-ray and optical imaging methods, we build a phase diagram for jetting and the absence of jetting. Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. The coalescence mechanism for bubble bursting may be useful in preventing jet formation in industry and improving climate models concerning aerosol production. PMID:21694715

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

2011-01-01

22

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

23

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

24

Penetration of the free surface by liquid jets in microgravity  

Microsoft Academic Search

This thesis presents a new computational model of the interaction between surface tension and jets emerging from the bulk liquid in microgravity. The model is compared to established models of liquid in liquid jet flow and then tested against drop tower test data. Results are found to be comparable in accuracy to prior work but able to study a much

David Joseph Chato

2004-01-01

25

Effects of cavitation in a nozzle on liquid jet atomization  

Microsoft Academic Search

Cavitation in two-dimensional (2D) nozzles and liquid jet in the vicinity of the nozzle exit were visualized using high-speed cameras to investigate the effects of cavitation on liquid jet under various conditions of cavitation and Reynolds numbers ? and Re. Liquid velocity in the nozzle was measured using a laser Doppler velocimetry to examine the effects of cavitation on the

Akira Sou; Shigeo Hosokawa; Akio Tomiyama

2007-01-01

26

Investigation on the submerged liquid jet arrays impingement cooling  

Microsoft Academic Search

The influence of jet arrays on heat transfer was experimentally and numerically studied. Four different arrays were tested using deionized water as the working liquid. The jets diameters ranged from 0.5 mm to 2.0 mm and the Reynolds number varied from 3500 to 12,000. Spacing of 3.5 mm between adjacent jets and 100 jets were used for the 0.5 mm diameter jet arrays while

Peng Tie; Qing Li; Yimin Xuan

2011-01-01

27

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

28

Nozzle geometry effects in liquid jet array impingement  

Microsoft Academic Search

The use of impinging liquid jets in electronics thermal management is attracting some consideration due to their very high heat transfer coefficients, hot spot targeting capabilities and moderate hydraulic power requirements. In this investigation an experimental study of the cooling capabilities of impinging water jet arrays is presented. Of particular interest here is the influence that the inlet and outlet

Brian P. Whelan; Anthony J. Robinson

2009-01-01

29

Time-resolved proper orthogonal decomposition of liquid jet dynamics  

Microsoft Academic Search

New insight into the mechanism of liquid jet in crossflow atomization is provided by an analysis technique based on proper orthogonal decomposition and spectral analysis. Data are provided in the form of high-speed videos of the jet near field from experiments over a broad range of injection conditions. For each condition, proper orthogonal modes (POMs) are generated and ordered by

Marco Arienti; Marios C. Soteriou

2009-01-01

30

Breakup of liquid jets from non-circular orifices  

NASA Astrophysics Data System (ADS)

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

Sharma, Priyesh; Fang, Tiegang

2014-02-01

31

Steady cone-jet electrosprays in liquid insulator baths.  

PubMed

This study shows that conducting liquids can be electrosprayed in steady cone-jet mode inside liquid insulator baths. Experimental results show that the current emitted from the meniscus fits well the scaling laws given in the literature for electrosprays in air at atmospheric pressure or vacuum. The technique may be of interest in obtaining fine liquid-liquid emulsions of uniformly sized droplets in the nanometric range. PMID:14985028

Barrero, A; López-Herrera, J M; Boucard, A; Loscertales, I G; Márquez, M

2004-04-01

32

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

33

Underexpanded noncondensing turbulent gas jets in liquids  

NASA Astrophysics Data System (ADS)

The structure of turbulent noncondensing round and plane air jets submerged in still water were investigated experimentally. Both adapted and underexpanded jets were considered, the latter with underexpansion ratios up to 8:1. Measurements included flow visualization, using flash photography and shadowgraphs as well as high-speed motion-picture photography; mean void fraction distributions, using gamma-ray absorption; entrainment rates, using laser-Doppler aneomometry; and mean static pressures, using static-pressure probes. Present measurements and the earlier results of Bell et al. (1972), Tross (1974) and Carreau et al. (1985) were used to evaluate analysis of the process. The analysis was based on the locally-homogeneous-flow approximation (relative velocities between the phases neglected) and the effective-adapted-jet approximation for underexpanded jets.

Loth, E.; Faeth, G. M.

1988-08-01

34

Noncondensing round turbulent gas jets in liquids  

NASA Astrophysics Data System (ADS)

The structure and mixing properties of noncondensing round turbulent air jets in still water was investigated experimentally, considering both subsonic and sonic underexpanded (with underexpanded ratios up to 8:1) jet exit conditions. Measurements included flow visualization, using flash and high-speed motion-picture photography; mean void fraction distributions, using deconvoluted gamma-ray absorption measurements; mean entrainment velocities, using laser-Doppler anemometry; and mean static pressures along the axis, using a static pressure probe. Analysis was also undertaken to help interpret the measurements, based on the locally-homogeneous-flow approximation (relative velocity differences between the phases neglected) and an effective-adapted-jet approximation for treating the mixing properties of the underexpanded jets.

Loth, E.; Faeth, G. M.

1987-10-01

35

Experimental investigation of charged liquid jet efflux from a capillary  

NASA Astrophysics Data System (ADS)

The shapes and electrical characteristics of charged liquid (water, ethanol, glycerol, castor oil) jets emitted from a metal capillary have been experimentally studied depending on the applied high voltage. A map of efflux regimes in the flow velocity-applied voltage coordinates is constructed for water. The effects of medium viscosity, surface tension, and charge relaxation time on the laws of jet efflux are analyzed.

Zhakin, A. I.; Belov, P. A.; Kuz'ko, A. E.

2013-03-01

36

Nozzle-geometry effects in liquid jet impingement heat transfer  

Microsoft Academic Search

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

Suresh V. Garimella; Boris Nenaydykh

1996-01-01

37

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

38

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

39

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

40

Shear flow control of gas jets in liquids  

NASA Astrophysics Data System (ADS)

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 have been initially tested in nonreacting gas/liquid systems. A large increase in the degree of mixing and jet stability occurs when non-axisymmetric nozzles are used as injectors relative to injection by axisymmetric Fanno tube type nozzles. Jet volume spreading rate is increased by a factor of 4. A characteristic instability (the 'reverse shock' or reverse flow effect) occurring in such two-phase systems is greatly reduced by passive control of the shear flow. A simple passive technique of controlling entrainment is described which is effective in eliminating the reverse flow effect. The relevance of these control techniques to liquid metal combustion is discussed.

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

1993-03-01

41

Shear flow control of gas jets in liquids  

NASA Astrophysics Data System (ADS)

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 have been initially tested in nonreacting gas/liquid systems. A large increase in degree of mixing and jet stability occurs when nonaxisymmetric nozzles are used as injectors relative to injection by axisymmetric Fanno tube type nozzles. Jet volume spreading rate is increased by a factor of 4. A characteristic instability (the 'reverse shock' or 'reverse flow' effect) occurring in such two-phase systems is greatly reduced by passive control of the shear flow. A simple passive technique of controlling entrainment is described which is effective in eliminating the reverse flow effect. The relevance of these control techniques to liquid metal combustion is discussed.

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

1992-07-01

42

Large bubble rupture sparks fast liquid jet.  

PubMed

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

Séon, Thomas; Antkowiak, Arnaud

2012-07-01

43

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

44

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

E-print Network

DYNAMICS OF LIQUID METAL JETS PENETRATING A STRONG MAGNETIC FIELD IN HIGH-POWER COLLIDERS A. Liquid metal jets (pulsed or continuous) are proposed as potential target candidates. Such a proposal poses two critical problems: penetration of a free liquid jet inside the required strong inhomogeneous

Harilal, S. S.

45

Converging swirling liquid jets from pressure swirl atomizers: Effect of inner air pressure  

NASA Astrophysics Data System (ADS)

Converging swirling liquid jets from pressure swirl atomizers injected into atmospheric air are studied experimentally using still and cine photographic techniques in the context of liquid-liquid coaxial swirl atomizers used in liquid rocket engines. The jet exhibits several interesting flow features in contrast to the nonswirling liquid jets (annular liquid jets) studied in the literature. The swirl motion creates multiple converging sections in the jet, which gradually collapse one after the other due to the liquid sheet breakup with increasing Weber number (We). This is clearly related to the air inside the converging jet which exhibits a peculiar variation of the pressure difference across the liquid sheet, ?P, with We. The variation shows a decreasing trend of ?P with We in an overall sense, but exhibits local maxima and minima at specific flow conditions. The number of maxima or minima observed in the curve depends on the number of converging sections seen in the jet at the lowest We. An interesting feature of this variation is that it delineates the regions of prominent jet flow features like the oscillating jet region, nonoscillating jet region, number of converging sections, and so on. Numerical predictions of the jet characteristics are obtained by modifying an existing nonswirling liquid jet model by including the swirling motion. The comparison between the experimental and numerical measurements shows that the pressure difference across the liquid sheet is important for the jet behavior and cannot be neglected in any theoretical analysis.

Sivakumar, D.; Raghunandan, B. N.

2002-12-01

46

Shock wave excited liquid micro-jets  

Microsoft Academic Search

The meniscus of the gas-water interface in a thin hydrophilic capillary of 1mm and less has some similarities to a ``shaped charge'' used to penetrated armored vehicles. In this presentation we show high-speed recordings of the interface dynamics after the reflection from a shock wave: the interface flattens and shapes into a microscopic needle-like jet, which accelerates to velocities of

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

2006-01-01

47

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.

48

Modeling of turbulence effect on liquid jet atomization  

NASA Astrophysics Data System (ADS)

Recent experimental investigations and physical modeling studies have indicated that turbulence behaviors within a liquid jet have considerable effects on the atomization process. Such turbulent flow phenomena are encountered in most practical applications of common liquid spray devices. Most existing atomization models do not account for the turbulence effects. Only limited attempts have been made to model the subject effects on the liquid jet disintegration; however, they treat the turbulence either as an only source or a primary driver in the breakup process. This doctoral research aims to model the effects of turbulence, occurring inside a cylindrical liquid jet, to its atomization process. The modeling effort enhances the predictions of the liquid jet breakup in more physically realistic operating conditions. In the course of this study, the two widely used atomization models, the Kelvin-Helmholtz (KH) instability of Reitz and the Taylor-Analogy-Breakup (TAB) of O'Rourke et al., portraying the primary liquid jet disintegration and the secondary droplet breakup respectively, are examined. Additional terms are formulated and implemented appropriately into these two models to account for the turbulence effect on the atomization process. In the primary breakup model, the turbulence inside the liquid jet is characterized by the turbulence scales and the initial turbulence quantities when incorporating into the Reitz model. Meanwhile, an additional turbulence effect acting on the parent drops is modeled and integrated into the TAB governing equation for the secondary breakup regime. The proposed extension of atomization models is assessed with a computer code written for simple flow situations. The 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 the ones without the turbulence. In contrast, the secondary droplet breakup with the inside liquid turbulence consideration produces smaller drops as compared to the case without the turbulence. Overall, the results are consistent with experimental observations from other researchers. Finally, the present models are also programmed into an existing computational fluid dynamic (CFD) code, and simulations for several experimental flow conditions are performed. The computational results suggest that the existing KH and TAB models tend to under-predict the product drop size and the spray angle. On the other hand, the proposed models provide the predictions, which agree reasonably well with available measured data. In summary, this research effort contributes to the improvement of the prediction in the liquid jet atomization processes. The additional terms, representing the turbulence effects on the jet breakup, can be incorporated easily into the two well-known atomization models. Suggested numerical schemes for solving the proposed models also are presented in this study. Therefore, the proposed enhancements can be implemented conveniently into existing CFD codes.

Trinh, Huu Phuoc

49

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

50

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

51

Droplet collisions after liquid jet breakup in microgravity conditions  

NASA Astrophysics Data System (ADS)

The droplet dynamics and collisions after a liquid jet breakup have been experimentally studied in low gravity conditions. An experimental setup was designed in order to be used at the I.N.T.A. Drop Tower, which allows for 2.1 seconds of microgravity. The dynamics of distilled water jets injected into a rectangular tank was recorded by means of a high-speed video camera. Observations of the droplet trajectories showed a conical shape of the liquid jet caused by droplet collisions just after detachment from the liquid jet. The detached droplets initially follow straight paths at constant velocity in the direction of injection. Deviation of these trajectories is a consequence of the collision between two droplets with an impact parameter slightly different from zero. The collision between two droplets can give rise to coalescence or bouncing between droplets depending on the droplet velocity difference and impact parameter. At low values of the relative velocity, the collision leads to coalescence between droplets, while at higher values the collision results in bouncing between droplets.

Suñol, F.; González-Cinca, R.

2011-12-01

52

The Plunge Phase of Friction Stir Welding  

NASA Technical Reports Server (NTRS)

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

Nunes, Arthur; McClure, John; Avila, Ricardo

2005-01-01

53

Restraint of Liquid Jets by Surface Tension in Microgravity Modeled  

NASA Technical Reports Server (NTRS)

Tension in Microgravity Modeled Microgravity poses many challenges to the designer of spacecraft tanks. Chief among these are the lack of phase separation and the need to supply vapor-free liquid or liquidfree vapor to the spacecraft processes that require fluid. One of the principal problems of phase separation is the creation of liquid jets. A jet can be created by liquid filling, settling of the fluid to one end of the tank, or even closing a valve to stop the liquid flow. Anyone who has seen a fountain knows that jets occur in normal gravity also. However, in normal gravity, the gravity controls and restricts the jet flow. In microgravity, with gravity largely absent, jets must be contained by surface tension forces. Recent NASA experiments in microgravity (Tank Pressure Control Experiment, TPCE, and Vented Tank Pressure Experiment, VTRE) resulted in a wealth of data about jet behavior in microgravity. VTRE was surprising in that, although it contained a complex geometry of baffles and vanes, the limit on liquid inflow was the emergence of a liquid jet from the top of the vane structure. Clearly understanding the restraint of liquid jets by surface tension is key to managing fluids in low gravity. To model this phenomenon, we need a numerical method that can track the fluid motion and the surface tension forces. The fluid motion is modeled with the Navier-Stokes equation formulated for low-speed incompressible flows. The quantities of velocity and pressure are placed on a staggered grid, with velocity being tracked at cell faces and pressure at cell centers. The free surface is tracked via the introduction of a color function that tracks liquid as 1/2 and gas as -1/2. A phase model developed by Jacqmin is used. This model converts the discrete surface tension force into a barrier function that peaks at the free surface and decays rapidly. Previous attempts at this formulation have been criticized for smearing the interface. However, by sharpening the phase function, double gridding the fluid function, and using a higher order solution for the fluid function, interface smearing is avoided. These equations can be rewritten as two coupled Poisson equations that also include the velocity. The method of solution is as follows: first, the phase equations are solved from this solution, a velocity field is generated, then a successive overrelaxation scheme is used to solve for a pressure field consistent with the velocity solution. After the code was implemented in axisymmetric form and verified by several test cases, the drop tower runs of Aydelott were modeled. The model handed the free-surface deformation quite nicely, even to the point of modeling geyser growth in the regime where the free surface was no longer restrained. A representative run is shown.

Chato, David J.

2001-01-01

54

Absolute and convective instability of a liquid jet  

NASA Astrophysics Data System (ADS)

Experiments on the absolute and convective instability of a liquid jet in microgravity were conducted at the NASA Lewis Research Center 2.2 second Drop Tower. A total of ten drop tests were performed with glycerin, and nineteen drop tests were performed with Dow Corning 200 series 1000 cSt silicone oil. An absolutely unstable liquid jet was photographed for the first time. Convective instability was characterized by disturbances that grew spatially in amplitude while being convected downstream, while absolute instability was characterized by disturbances that grew rapidly in both space and time, as predicted by the theory. The transitional Reynolds and Weber numbers were also identified and compared with the theoretical prediction.

Vihinen, I.; Lin, S. P.; Chen, J. N.

1996-11-01

55

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

E-print Network

. The paper explores the opposite case in which the jet is disturbed so as to form an axisymmetric troughMechanism 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

Ohl, Claus-Dieter

56

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.

57

Effect of gas mass flux on cryogenic liquid jet breakup  

NASA Technical Reports Server (NTRS)

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

Ingebo, R. D.

1992-01-01

58

Newtonian liquid jet impaction on a high-speed moving surface  

Microsoft Academic Search

In the railroad industry a friction modifying agent may be applied to the rail or wheel in the form of a liquid jet. In this mode of application the interaction between the high-speed liquid jet and a fast moving surface is important. Seven different Newtonian liquids with widely varying shear viscosities were tested to isolate the effect of viscosity from

B. Keshavarz; S. I. Green; M. H. Davy; D. T. Eadie

59

Production of jet fuel from coal-derived liquids  

SciTech Connect

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

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

1987-01-01

60

Cone-jet electrospray in a dielectric liquid atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

61

Liquid jet generated by thermocavitation bubbles within a droplet  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

62

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

63

Acoustic excitation of liquid fuel droplets and coaxial jets  

NASA Astrophysics Data System (ADS)

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

Rodriguez, Juan Ignacio

64

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

65

Atmospheric pressure plasma jets interacting with liquid covered tissue: touching and not-touching the liquid  

NASA Astrophysics Data System (ADS)

In the use of atmospheric pressure plasma jets in biological applications, the plasma-produced charged and neutral species in the plume of the jet often interact with a thin layer of liquid covering the tissue being treated. The plasma-produced reactivity must then penetrate through the liquid layer to reach the tissue. In this computational investigation, a plasma jet created by a single discharge pulse at three different voltages was directed onto a 200?µm water layer covering tissue followed by a 10?s afterglow. The magnitude of the voltage and its pulse length determined if the ionization wave producing the plasma plume reached the surface of the liquid. When the ionization wave touches the surface, significantly more charged species were created in the water layer with H3O+aq, O3?aq, and O2?aq being the dominant terminal species. More aqueous OHaq, H2O2aq, and O3aq were also formed when the plasma plume touches the surface. The single pulse examined here corresponds to a low repetition rate plasma jet where reactive species would be blown out of the volume between pulses and there is not recirculation of flow or turbulence. For these conditions, NxOy species do not accumulate in the volume. As a result, aqueous nitrites, nitrates, and peroxynitrite, and the HNO3aq and HOONOaq, which trace their origin to solvated NxOy, have low densities.

Norberg, Seth A.; Tian, Wei; Johnsen, Eric; Kushner, Mark J.

2014-11-01

66

Numerical Simulation of Liquid Jet Atomization Including Turbulence Effects  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

67

The Liquid Argon Jet Trigger of the H1 Experiment at HERA  

E-print Network

The Liquid Argon Jet Trigger, installed in the H1 experiment at HERA, implements in 800 ns a real-time cluster algorithm by finding local energy maxima, summing their immediate neighbors, sorting the resulting "jets" by energy, and applying topological conditions. It operated since the year 2006 and drastically reduced the thresholds for triggering on electrons and jets.

Bob Olivier

2008-11-01

68

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

69

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

Microsoft Academic Search

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)

Manfred Faubel; Björn Steiner; J. Peter Toennies

1997-01-01

70

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

71

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

NASA Astrophysics Data System (ADS)

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

Ghods, Sina

72

Effect of gravity on capillary instability of liquid jets.  

PubMed

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

Amini, Ghobad; Ihme, Matthias; Dolatabadi, Ali

2013-05-01

73

Experimental and theoretical studies of vertical annular liquid jets  

Microsoft Academic Search

Theoretical studies are described of vertical annular jets, the conditions are determined under which vertical jets form an enclosed volume which can be used as a chemical reactor, the influence is assessed of the nozzle gap width, nozzle geometry, pressure difference across the annular jet, and Froude, Weber and Reynolds numbers on the annular jet's covergence length, and the mass

J. I. Ramos

1990-01-01

74

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

SciTech Connect

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

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

2010-02-01

75

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.

76

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

77

Steady laminar flow of liquid-liquid jets at high Reynolds numbers*  

NASA Astrophysics Data System (ADS)

The axisymmetric steady-state laminar flow of a Newtonian liquid jet injected vertically into another immiscible Newtonian liquid is investigated for various Reynolds numbers. The steady-state solution was calculated by solving the axisymmetric transient equations of motion and continuity using a numerical scheme based on the volume of fluid (VOF) method combined with the new continuum surface force (CSF) algorithm. The analysis takes into account pressure, viscous, inertial, gravitational, and surface tension forces. Comparison with previous experimental measurements, performed on a xylene/water system, under conditions where all of these forces are important, shows good agreement over the entire range of conditions studied. Comparisons of the present numerical method with the numerical results of previous boundary-layer methods help establish their range of validity.

Richards, John R.; Beris, Antony N.; Lenhoff, Abraham M.

1993-07-01

78

Hybrid Liquid Immersion and Synthetic Jet Heat Sink for Cooling 3-D Stacked Electronics  

Microsoft Academic Search

This paper focuses on the design and parametric numerical study of a hybrid heat sink combining a liquid thermal interface with an array of synthetic jet actuators for 3-D chip stack cooling. The air-side heat sink exploits enhanced localized heat transfer achieved via a central array of synthetic jet actuators. The key focus of this paper is the numerical simulation

Krishna Kota; Pablo Hidalgo; Yogendra Joshi; Ari Glezer

2012-01-01

79

Jet formation upon ultrafast laser induced breakdown in the vicinity of liquid-gas interface  

NASA Astrophysics Data System (ADS)

We have studied the phenomenon of breakdown in liquids under the action of ultrashort (160 fs) laser pulses focused in the vicinity of a flat or curved liquid-gas interface. It is established that a slightly divergent jet containing micron-sized bubbles is formed in the liquid, which originates from the laser-induced breakdown zone and propagates inward the liquid along the normal drawn to the interface from the point of laser beam focusing. The jet length depends on the distance from this focal point to the interface, as well as on the energy, and the repetition rate of laser pulses and can reach several centimeters.

Oshemkov, S. V.; Dvorkin, L. P.; Dmitriev, V. Yu.

2008-05-01

80

Jet formation upon ultrafast laser induced breakdown in the vicinity of liquid-gas interface  

Microsoft Academic Search

We have studied the phenomenon of breakdown in liquids under the action of ultrashort (160 fs) laser pulses focused in the vicinity of a flat or curved liquid-gas interface. It is established that a slightly divergent jet containing micron-sized bubbles is formed in the liquid, which originates from the laser-induced breakdown zone and propagates inward the liquid along the normal

S. V. Oshemkov; L. P. Dvorkin; V. Yu. Dmitriev

2008-01-01

81

Jet formation upon ultrafast laser induced breakdown in the vicinity of liquid-gas interface  

Microsoft Academic Search

We have studied the phenomenon of breakdown in liquids under the action of ultrashort (160 fs) laser pulses focused in the\\u000a vicinity of a flat or curved liquid-gas interface. It is established that a slightly divergent jet containing micron-sized\\u000a bubbles is formed in the liquid, which originates from the laser-induced breakdown zone and propagates inward the liquid along\\u000a the normal

S. V. Oshemkov; L. P. Dvorkin; V. Yu. Dmitriev

2008-01-01

82

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

83

Primary atomization of liquid jets issuing from rocket engine coaxial injectors  

NASA Astrophysics Data System (ADS)

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid-propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their optical opacity. This work focuses on a characteristic of the primary breakup process of round liquid jets, namely the length of the intact liquid core. The specific application considered is that of shear-coaxial type rocket engine injectors. Real-time x-ray radiography, capable of imaging through the dense two-phase region surrounding the liquid core, has been used to make the measurements. Nitrogen and helium were employed as the fuel simulants while an x-ray absorbing potassium iodide aqueous solution was used as the liquid oxygen (LOX) simulant. The intact-liquid-core length data have been obtained and interpreted to illustrate the effects of chamber pressure (gas density), injected-gas and liquid velocities, and cavitation. The results clearly show that the effect of cavitation must be considered at low chamber pressures since it can be the dominant breakup mechanism. A correlation of intact core length in terms of gas-to-liquid density ratio, liquid jet Reynolds number, and Weber number is suggested. The gas-to-liquid density ratio appears to be the key parameter for aerodynamic shear breakup in this study. A small number of hot-fire, LOX/hydrogen tests were also conducted to attempt intact-LOX-core measurements under realistic conditions in a single-coaxial-element rocket engine. The tests were not successful in terms of measuring the intact core, but instantaneous imaging of LOX jets suggests that LOX jet breakup is qualitatively similar to that of cold-flow, propellant-simulant jets. The liquid oxygen jets survived in the hot-fire environment much longer than expected, and LOX was even visualized exiting the chamber nozzle under some conditions. This may be an effect of the single element configuration.

Woodward, Roger D.

1993-01-01

84

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

85

Analysis of heat transfer for a normally impinging liquid-metal slot jet  

NASA Technical Reports Server (NTRS)

A two-dimensional liquid-metal slot jet that is impinging normally against a uniformly heated flat plate is analyzed. The distributions of wall temperature and heat-transfer coefficient are obtained as functions of position along the plate. The liquid-metal assumptions are made that the jet is inviscid and that molecular condition is dominating heat diffusion. The solution is obtained by mapping the jet flow region into a potential plane where it occupies a strip of uniform width. The energy equation is transformed into potential coordinates, and an exact solution obtained in the strip region. Conformal mapping is then used to transform the solution into the physical plane.

Siegel, R.

1973-01-01

86

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

87

Analytical description of the breakup of liquid jets in air  

NASA Technical Reports Server (NTRS)

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

Papageorgiou, Demetrios T.

1993-01-01

88

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

89

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

90

Detailed Numerical Simulation of Liquid Jet in Cross Flow Atomization with High Density Ratios  

NASA Astrophysics Data System (ADS)

Atomization of a liquid fluid jet by a high speed cross-flowing gas has many applications such as gas turbines and augmentors. The mechanisms by which the liquid jet initially breaks up, however, are not well understood. Detailed numerical simulation can offer a better understanding of the underlying physical mechanisms that lead to the initial breakup of the injected liquid jet. In this work, we present detailed numerical simulation results of turbulent liquid jets injected into turbulent gaseous cross flows at varying momentum flux ratios and crossflow Weber numbers. We employ a finite volume, balanced force fractional step flow solver to solve the Navier-Stokes equations coupled to a Refined Level Set Grid method to follow the phase interface. To ensure discrete consistency between the solution of the conservative momentum equation and the level set based continuity equation, we employ a novel Rescaled Conservative Momentum Method. We analyze the impact of the previously-mentioned characteristic numbers on jet penetration, atomization mechanism, liquid mass flux distribution, and resulting drop size distribution and compare our numerical results to those obtained experimentally by Brown & McDonell (2006).

Ghods, Sina; Herrmann, Marcus

2011-11-01

91

Droplet formation from the breakup of micron-sized liquid jets  

NASA Astrophysics Data System (ADS)

Droplet formation from the breakup of a liquid jet emerging from a micron-sized circular nozzle is investigated with ultra high-speed imaging at 1 million frames per second and within a lubrication approximation model [Eggers and Dupont, Phys. Rev. Lett. 262, 1994, 205-221]. The capillary time ?c= ??r^3 / ? is extremely small -- of the order of 1?s. In the analyzed low Reynolds number regime the jet breakup is driven by surface tension forces only. Rayleigh breakup is not influenced by the surrounding air. The high- speed imaging results and those from the model calculation perfectly agree for various liquid viscosities and jet velocities, confirming a universal scaling law also for diminutive Rayleigh jets.

van Hoeve, Wim; van der Bos, Arjan; Versluis, Michel; Snoeijer, Jacco; Brenner, Michael P.; Lohse, Detlef

2009-11-01

92

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

93

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

94

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

95

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

96

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

NASA Technical Reports Server (NTRS)

An analytical study of the breakup, burning, and ignition of liquid fuels injected transversely into a hot air stream is conducted. The non-reacting liquid jet breakup location is determined by the local sonic point criterion. Two models, one employing analysis of an elliptical jet cross-section and the other employing a two-dimensional blunt body to represent the transverse jet, were used 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 cross flow. Typical flame structures and concentration profiles were calculated for various locations along the jet cross-section as a function of upstream Mach numbers. The integration 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, Hsi-Shang

1990-01-01

97

Flowing liquid sample jet for resonance Raman and ultrafast optical spectroscopy  

NASA Astrophysics Data System (ADS)

A wire-guided, gravity-driven jet apparatus is described that produces optically stable thin films of liquids flowing at rates suitable for high repetition rate spectroscopy. Unlike conventional free-flowing jets, the design works well for low viscosity solvents including water and aqueous solutions of proteins. The construction of the wire guide, jet nozzle, and flow system is described. A stable water film whose thickness can be varied from 6 to 100 ?m is demonstrated that has been employed in resonance Raman and femtosecond transient absorption experiments.

Tauber, Michael J.; Mathies, Richard A.; Chen, Xiyi; Bradforth, Stephen E.

2003-11-01

98

Confined jet impingement of liquid nitrogen onto different heat transfer surfaces  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

99

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

100

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

101

Axisymmetric confined turbulent jet directed towards the liquid surface from below  

NASA Technical Reports Server (NTRS)

A numerical simulation is presented of an axisymmetric turbulent jet discharging axially from below into a cylindrical tank and directed towards the liquid vapor interface. The liquid vapor interface is assumed to be flat and shear free. The k-epsilon turbulence model is used to calculate the eddy viscosity. The turbulence intensity distribution and the length scale associated with the k-epsilon model are calculated as functions of jet flow rates and systems parameters. Numerical results are compared with appropriate experimental data. The problems associated with the free surface boundary conditions for the turbulent quantities are discussed.

Hasan, Mohammad M.; Lin, Chin-Shun

1988-01-01

102

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

2001-11-18

103

Visualization of laser-induced liquid micro-jet disintegration by means of high-speed video stroboscopy  

Microsoft Academic Search

In the present paper we describe a novel approach to monitor and to investigate laser induced liquid water jet disintegration in air and in vacuum. The features of liquid beam disintegration in vacuum are of importance for pulsed laser induced liquid beam desorption mass spectrometry and micro-calorimetry. Due to the small liquid beam diameter of 12-15 µm, its high speed

Boleslaw Stasicki; Ales Charvat; Manfred Faubel; Bernd Abel

2005-01-01

104

The Plunge Phase of Friction Stir Welding  

NASA Technical Reports Server (NTRS)

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

McClure, John C.

2005-01-01

105

Instability of elliptic liquid jets: Temporal linear stability theory and experimental analysis  

NASA Astrophysics Data System (ADS)

The instability dynamics of inviscid liquid jets issuing from elliptical orifices is studied, and effects of the surrounding gas and the liquid surface tension on the stability behavior are investigated. A dispersion relation for the zeroth azimuthal (axisymmetric) instability mode is derived. Consistency of the analysis is confirmed by demonstrating that these equations reduce to the well-known dispersion equations for the limiting cases of round and planar jets. It is shown that the effect of the ellipticity is to increase the growth rate over a large range of wavenumbers in comparison to those of a circular jet. For higher Weber numbers, at which capillary forces have a stabilizing effect, the growth rate decreases with increasing ellipticity. Similar to circular and planar jets, increasing the density ratio between gas and liquid increases the growth of disturbances significantly. These theoretical investigations are complemented by experiments to validate the local linear stability results. Comparisons of predicted growth rates with measurements over a range of jet ellipticities confirm that the theoretical model provides a quantitatively accurate description of the instability dynamics in the Rayleigh and first wind-induced regimes.

Amini, Ghobad; Lv, Yu; Dolatabadi, Ali; Ihme, Matthias

2014-11-01

106

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

107

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

108

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

109

Numerical investigation of liquid jet Proposition: Combined internship / master thesis 2014-2015  

E-print Network

Numerical investigation of liquid jet breakup Proposition: Combined internship / master thesis 2014-2015 be described either by an Euler or by a Lagrange formulation. The aim of this internship/master thesis Interested in an internship ­ master thesis at Umicore? For any further information please contact Marcus

Wolper, Pierre

110

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

SciTech Connect

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

Gomes, R. B.; Fernandes, H.; Silva, C.; Borba, D.; Carvalho, B.; Varandas, C. [Associacao EURATOM/IST, Centro de FuSao Nuclear, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Lielausis, O.; Klyukin, A.; Platacis, E.; Mikelsons, A.; Platnieks, I. [Association EURATOM/University of Latvia, Institute of Physics, 32 Miera Str., Salaspils, LV-2169 (Latvia)

2006-12-04

111

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

112

Deformation and breakup of round drops and nonturbulent liquid jets in uniform crossflows  

NASA Astrophysics Data System (ADS)

The deformation and breakup properties of liquid drops and round liquid jets in uniform crossflows were studied computationally, motivated by applications to the behavior of sprays in crossflows found in a variety of power and propulsion systems. The objective of the present investigation was to extend the parameter range of past deformation and breakup studies, by means of numerical computations, to conditions more representative of practical high-pressure spray combustion processes. The time-dependent, incompressible and two-dimensional Navier-Stokes equations were solved on a uniform, staggered grid using the projection method of Chorin (1968) and the Level Set method of Sussman et al. (1994). Numerical simulations of the effect of crossflows on the deformation and breakup of drops and round liquid jets were carried out for the following range of parameters to study the independent effects of four dimensionless variables that fully describe the problem: Weber numbers of 0.1--2,000,000, Ohnesorge numbers of 0.001--100, Reynolds numbers of 12.5--200 and liquid/gas density ratios of 2--infinity (the last by Richardson extrapolation). The present results were in good agreement with existing measurements of deformation and breakup properties of both liquid drops and round liquid jets at large liquid/gas density ratios and with wake and drag properties of spheres and cylinders in crossflows. Similar to past experimental observations, remarkable similarities were observed between the breakup properties of round liquid jets and liquid drops. The liquid/gas density ratio was found to have a relatively small effect on deformation and breakup. Effects of Reynolds number variations were also small for conditions where the drag coefficient is relatively independent of the Reynolds number. As the Stokes flow regime is approached, however, the Weber number (We) required for breakup increases significantly due to increased drag coefficients. At large Ohnesorge number (Oh) conditions, where liquid viscous forces dominate surface tension forces, breakup is best defined in terms of a critical ratio of drag forces to liquid viscous forces, We 1/2/Oh, and plotting We1/2 /Oh vs. 1/Oh yielded breakup regime boundaries that were relatively constant for large Oh and largely independent of other parameters of the flow.

Aalburg, Christian

2002-09-01

113

Traction Drive Inverter Cooling with Submerged Liquid Jet Impingement on Microfinned Enhanced Surfaces (Presentation)  

SciTech Connect

Jet impingement is one means to improve thermal management for power electronics in electric-drive traction vehicles. Jet impingement on microfin-enhanced surfaces further augments heat transfer and thermal performance. A channel flow heat exchanger from a commercial inverter was characterized as a baseline system for comparison with two new prototype designs using liquid jet impingement on plain and microfinned enhanced surfaces. The submerged jets can target areas with the highest heat flux to provide local cooling, such as areas under insulated-gate bipolar transistors and diode devices. Low power experiments, where four diodes were powered, dissipated 105 W of heat and were used to validate computational fluid dynamics modeling of the baseline and prototype designs. Experiments and modeling used typical automotive flow rates using water-ethylene glycol as a coolant (50%-50% by volume). The computational fluid dynamics model was used to predict full inverter power heat dissipation. The channel flow and jet impingement configurations were tested at full inverter power of 40 to 100 kW (output power) on a dynamometer, translating to an approximate heat dissipation of 1 to 2 kW. With jet impingement, the cold plate material is not critical for the thermal pathway. A high-temperature plastic was used that could eventually be injection molded or formed, with the jets formed from a basic aluminum plate with orifices acting as nozzles. Long-term reliability of the jet nozzles and impingement on enhanced surfaces was examined. For jet impingement on microfinned surfaces, thermal performance increased 17%. Along with a weight reduction of approximately 3 kg, the specific power (kW/kg) increased by 36%, with an increase in power density (kW/L) of 12% compared with the baseline channel flow configuration.

Waye, S.; Narumanchi, S.; Moreno, G.

2014-09-01

114

Influence of Turbulence on the Restraint of Liquid Jets by Surface Tension in Microgravity Investigated  

NASA Technical Reports Server (NTRS)

Microgravity poses many challenges to the designer of spacecraft tanks. Chief among these are the lack of phase separation and the need to supply vapor-free liquid or liquidfree vapor to the spacecraft processes that require fluid. One of the principal problems of phase separation is the creation of liquid jets. A jet can be created by liquid filling, settling of the fluid to one end of the tank, or even closing a valve to stop the liquid flow. Anyone who has seen a fountain knows that jets occur in normal gravity also. However, in normal gravity, the gravity controls and restricts the jet flow. In microgravity, with gravity largely absent, surface tension forces must contain jets. To model this phenomenon, a numerical method that tracks the fluid motion and the surface tension forces is required. Jacqmin has developed a phase model that converts the discrete surface tension force into a barrier function that peaks at the free surface and decays rapidly away. Previous attempts at this formulation were criticized for smearing the interface. This can be overcome by sharpening the phase function, double gridding the fluid function, and using a higher order solution for the fluid function. The solution of this equation can be rewritten as two coupled Poisson equations that also include the velocity. After the code was implemented in axisymmetric form and verified by several test cases at the NASA Glenn Research Center, the drop tower runs of Aydelott were modeled. Work last year with a laminar model was found to overpredict Aydelott's results, except at the lowest Reynolds number conditions of 400. This year, a simple turbulence model was implemented by adding a turbulent viscosity based on the mixing-length hypothesis and empirical measurements of previous works. Predictions made after this change was implemented have been much closer to experimentally observed flow patterns and geyser heights. Two model runs is shown. The first, without any turbulence correction, breaks through the free surface and strikes the far end of the tank. In the second, the turbulence spreads the jet momentum over more of the free surface, enabling the surface tension forces to turn the jet back into the bulk liquid. The model geyser height with the second model is 1.1 cm. This is quite close to the 1.5-cm geyser height measured by Aydelott.

Chato, David J.

2002-01-01

115

Journal of Fluid Mechanics Plunging cavities  

E-print Network

interesting links with other transient cavities. Key words: bubble dynamics, free-surface flows, jets, wave breaking 1. Introduction Water waves break in a wide range of conditions (Battjes 1988; Banner & Peregrine from Zhu, Oguz & Prosperetti (2000), a vertical cylindrical water jet of diameter Dj = 5.4 mm

Boyer, Edmond

116

Vehicle-scale investigation of a fluorine jet-pump liquid hydrogen tank pressurization system  

NASA Technical Reports Server (NTRS)

A comprehensive analytical and experimental program was performed to evaluate the performance of a fluorine-hydrogen jet-pump injector for main tank injection (MTI) pressurization of a liquid hydrogen (LH2) tank. The injector performance during pressurization and LH2 expulsion was determined by a series of seven tests of a full-scale injector and MTI pressure control system in a 28.3 cu m (1000 cu ft) flight-weight LH2 tank. Although the injector did not effectively jet-pump LH2 continuously, it showed improved pressurization performance compared to straight-pipe injectors tested under the same conditions in a previous program. The MTI computer code was modified to allow performance prediction for the jet-pump injector.

Cady, E. C.; Kendle, D. W.

1972-01-01

117

Effect of Liquid Droplets on Turbulence Structure in a Round Gaseous Jet  

NASA Technical Reports Server (NTRS)

A second-order model which predicts the modulation of turbulence in jets laden with uniform size solid particles or liquid droplets is discussed. The approach followed is to start from the separate momentum and continuity equations of each phase and derive two new conservation equations. The first is for the carrier fluid's kinetic energy of turbulence and the second for the dissipation rate of that energy. Closure of the set of transport equations is achieved by modeling the turbulence correlations up to a third order. The coefficients (or constants) appearing in the modeled equations are then evaluated by comparing the predictions with LDA-measurements obtained recently in a turbulent jet laden with 200 microns solid particles. This set of constants is then used to predict the same jet flow but laden with 50 microns solid particles. The agreement with the measurement in this case is very good.

Elghobashi, S. E.; Mostafa, A. M.

1983-01-01

118

Dynamics of Pinch-Off in Immiscible Liquid/Liquid Jets  

NASA Astrophysics Data System (ADS)

The behavior of glycerine/water jets flowing into a nearly immiscible ambient of Dow Corning 200 fluid is investigated using laser induced fluorescence flow visualization and particle image velocimetry. Clear images are obtained by matching the index of refraction in the glycerine/water solution with the index of refraction in the surrounding Dow Corning fluid. Jet Reynolds numbers are on the order of 100. The pinch-off of the jet column into droplets can be made repeatable by periodic forcing, and several pinch-off modes are examined. These modes are produced by varying the forcing frequency and amplitude, fluid viscosity ratio, and jet Reynolds number. The details of the pinch-off, including local variations in concentration near the transition location and the associated velocity fields will be discussed. The experimental results will be compared with numerical simulations that allow limited chemical mixing across the finite-thickness interface.

Longmire, E. K.; Webster, D. R.; Lowengrub, J. S.

1997-11-01

119

Performance Improvement of a Power Conversion Module by Liquid MicroJet Impingement Cooling  

Microsoft Academic Search

Liquid micro-jet array impingement cooling of a power conversion module with 12 power switching devices (six insulated gate bipolar transistors and six diodes) is investigated. The 1200-V\\/150-A module converts dc input power to variable frequency, variable voltage three-phase ac output to drive a 50HP three-phase induction motor. The silicon devices are attached to a packaging layer [direct bonded copper (DBC)],

Avijit Bhunia; Sriram Chandrasekaran; Chung-Lung Chen

2007-01-01

120

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

121

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

122

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

123

Jet pinch-off and drop formation in immiscible liquid-liquid systems  

NASA Astrophysics Data System (ADS)

The behavior of glycerin-water jets flowing into immiscible ambients of Dow Corning 200 fluid was investigated using laser induced fluorescence (LIF). Undistorted images were obtained by matching the index of refraction of the fluids. A sinusoidal perturbation was superposed on the flow to phase lock the drop formation. The forcing frequency dramatically affected the size, spacing, and number of drops that formed within a forcing cycle and the angle between drops and the jet interface just before pinch-off. Two fluid combinations were studied with similar density ratios, but viscosity ratios differing by a factor of 20. The viscosity ratio affected the jet stability as well as pinch-off angles and drop size.

Webster, D. R.; Longmire, E. K.

124

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

125

Direct numerical simulation of the near-field dynamics of annular gas-liquid two-phase jets  

NASA Astrophysics Data System (ADS)

Direct numerical simulation has been used to examine the near-field dynamics of annular gas-liquid two-phase jets. Based on an Eulerian approach with mixed fluid treatment, combined with an adapted volume of fluid method and a continuum surface force model, a mathematical formulation for the flow system is presented. The swirl introduced at the jet nozzle exit is based on analytical inflow conditions. Highly accurate numerical methods have been utilized for the solution of the compressible, unsteady, Navier-Stokes equations. Two computational cases of gas-liquid two-phase jets including swirling and nonswirling cases have been performed to investigate the effects of swirl on the flow field. In both cases the flow is more vortical at the downstream locations. The swirling motion enhances both the flow instability resulting in a larger liquid spatial dispersion and the mixing resulting in a more homogeneous flow field with more evenly distributed vorticity at the downstream locations. In the annular nonswirling case, a geometrical recirculation zone adjacent to the jet nozzle exit was observed. It was identified that the swirling motion is responsible for the development of a central recirculation zone, and the geometrical recirculation zone can be overwhelmed by the central recirculation zone leading to the presence of the central recirculation region only in the swirling gas-liquid case. Results from a swirling gas jet simulation were also included to examine the effect of the liquid sheet on the flow physics. The swirling gas jet developed a central recirculation region, but it did not develop a precessing vortex core as the swirling gas-liquid two-phase jet. The results indicate that a precessing vortex core can exist at relatively low swirl numbers in the gas-liquid two-phase flow. It was established that the liquid greatly affects the precession and the swirl number alone is an insufficient criterion for the development of a precessing vortex core.

Siamas, George A.; Jiang, Xi; Wrobel, Luiz C.

2009-04-01

126

Self-assembling array of magnetoelectrostatic jets from the surface of a superparamagnetic ionic liquid.  

PubMed

Electrospray is a versatile technology used, for example, to ionize biomolecules for mass spectrometry, create nanofibers and nanowires, and propel spacecraft in orbit. Traditionally, electrospray is achieved via microfabricated capillary needle electrodes that are used to create the fluid jets. Here we report on multiple parallel jetting instabilities realized through the application of simultaneous electric and magnetic fields to the surface of a superparamagnetic electrically conducting ionic liquid with no needle electrodes. The ionic liquid ferrofluid is synthesized by suspending magnetic nanoparticles in a room-temperature molten salt carrier liquid. Two ILFFs are reported: one based on ethylammonium nitrate (EAN) and the other based on EMIM-NTf2. The ILFFs display an electrical conductivity of 0.63 S/m and a relative magnetic permeability as high as 10. When coincident electric and magnetic fields are applied to these liquids, the result is a self-assembling array of emitters that are composed entirely of the colloidal fluid. An analysis of the magnetic surface stress induced on the ILFF shows that the electric field required for transition to spray can be reduced by as much as 4.5 × 10(7) V/m compared to purely electrostatic spray. Ferrofluid mode studies in nonuniform magnetic fields show that it is feasible to realize arrays with up to 16 emitters/mm(2). PMID:25372842

King, Lyon B; Meyer, Edmond; Hopkins, Mark A; Hawkett, Brian S; Jain, Nirmesh

2014-12-01

127

Sun-plunging Comets and Cometary Flares  

NASA Astrophysics Data System (ADS)

During 2011, NASA's Solar Dynamics Observatory (SDO) made the first ever direct observations of sun-grazing comet destruction in the inner solar atmosphere. On July 6, the nucleus material of Comet C/2011 N3 (SOHO) (perihelion distance q~1.14R_sun) was observed to vaporize, decelerate and radiate, with total nucleus destruction over a path length ~ R_sun through the lower corona (density n ~ 10^8/cm^3). On Dec. 16, the much more massive Comet C/2011 W3 (Lovejoy), with similar q~1.17 R_sun), was seen vaporizing until it vanished behind the solar limb then re-emerging in a much diminished state. A range of current work on these data is being presented by others in this AGU session. These two 'sun-skimming' comets had q in the low corona. There, mass loss is dominated by insolation-driven sublimation, so the physics of their destruction is largely similar to those with q>> R_sun. However, Brown et al. (Astron. Astrophys. 535, A71, 2011) showed that mass loss and destruction is completely different for 'sun-plunging' comets with qn*= 2.5x10^11/cm^3, increasing exponentially with depth on scale height H~100-500 km). Consequently sun-plunger mass loss and destruction is dominated by ablation and by ram-pressure-driven explosion. The very large cometary kinetic energy (2x10^27 erg x (M/10^12) for mass M g) and its highly localized deposition in time (<10 s) and space (<6000 km ~ 10") should produce signatures somewhat like solar magnetic flares. Such 'cometary flare' events should offer wholly new ways to probe properties both of comets (e.g. element abundances) and of the low solar atmosphere (e.g magnetic fields). Super-flares produced by very large sun-plungers could have serious terrestrial consequences. We will present and discuss results of our current work on sun-plunging comets and explosive cometary flares, including - - Likely rate of occurrence of detectable cometary flares, in terms of the statistical distribution of relevant cometary masses M and of orbital q values. - Comparison of Brown et al's analytic estimates of their properties with those from numerical simulations, developed by modifying Carlson et al's (Icarus 121,228, 1997) Shoemaker-Levy-9 Jupiter impact model. The much higher comet-sun impact velocity compared to that for SL-9-Jupiter requires the addition of various effects, including solar, thermal, and radiative ablation, to hydrodynamic radial expansion of the impactor ,and subsequent fragmentation. The solar atmosphere's much higher temperature and ionization and lower density than Jupiter's also modify the "airburst" conditions. - Predictive estimates of the observational signatures of such explosions and their practical observability.

Brown, J. C.; Carlson, R. W.

2012-12-01

128

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

129

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.

130

Experimental investigation and model improvement on the atomization performance of single-hole Y-jet nozzle with high liquid flow rate  

Microsoft Academic Search

Y-jet nozzle, as an efficient multi-hole internal-mixing twin-fluid atomizer, has been widely used for liquid fuel spray in many industrial processes. However, single-hole Y-jet nozzle with high liquid flow rate is indispensable in some confined situations due to a small spray cone angle. In this paper, the atomization performance of single-hole Y-jet nozzles with high liquid mass flow rates ranging

Yuegui Zhou; Mingchuan Zhang; Juan Yu; Xian Zhu; Jun Peng

2010-01-01

131

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

132

Numerical analysis of the temporal and spatial instabilities on an annular liquid jet  

NASA Astrophysics Data System (ADS)

A numerical study of the temporal and spatial instabilities appearing on the interface of an annular liquid jet emerging from an orifice and flowing into a high pressure gas medium has been performed using Direct Numerical Simulation. The purpose of this study is to gain a better insight into the dominant mechanisms in the atomization of annular liquid jets during the start-up portion of the injection. The effects on the growth rate and wavelength of the emerging Kelvin-Helmholtz and Rayleigh-Taylor instabilities of various flow parameters have been investigated: the Reynolds and Weber numbers; fluids properties like gas-to-liquid density and viscosity ratios; and geometrical parameters involved in the problem such as thickness-to-diameter ratio of the liquid sheet. The Reynolds numbers used in this study are in the range from 3,000 to 30,000, and the Weber numbers are in the range of 6,000 up to 150,000. The convergence rate and length of the liquid jet has been also computed and compared for different cases. A characteristic convergence time has been proposed based on the obtained results. Use has been made of an unsteady axisymmetric code with a finite-volume solver of the Navier-Stokes equations for liquid streams and adjacent gas and a level-set method for the liquid/gas interface tracking. Two significant velocity reversals were detected on the axis of symmetry for all flow Reynolds numbers; the one closer to the nozzle exit being attributed to the recirculation zone, and the one farther downstream corresponding to the annular jet collapse on the centerline. The effects of different flow parameters on the location of these velocity reversals are studied. The results indicate that the convergence length and time increase significantly with the gas density and liquid viscosity and decrease with the liquid sheet thickness, while the effects of the gas viscosity and the surface tension are not so considerable. The range of unstable Kelvin-Helmholtz and Rayleigh-Taylor wavelengths have been also studied. The statistical data obtained from the numerical results show that, the average normalized wavelength of the KH instabilities decreases with the Reynolds and Weber numbers and the sheet thickness, and increases with the gas-to-liquid density ratio, and is independent of the viscosity ratio. The wavelength of the KH instabilities were observed to increase in time, except for the very thin liquid sheet, where the average KH wavelength oscillates between two values, indicating occurrence of different sheet breakup cycles. The sheet breakup times and lengths were reported up to the second sheet breakup, and it is shown that the later sheet breakups happen closer to the nozzle exit plane. The RT wavelengths tend to decrease during the start-up period of injection.

Zandian, Arash

133

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

134

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

135

Interfacial and velocity characteristics of pinch-off modes in liquid/liquid jet systems  

NASA Astrophysics Data System (ADS)

Forced jets of water/glycerin mixture flowing into silicone oil were investigated. An index-matching technique was employed, and the flow was examined by laser-induced fluorescence and PIV. Experiments were performed at several Reynolds and Strouhal numbers (Re 50-80, St 2-3) while holding viscosity ratio (mi/mo = 1.6) and Ohnesorge number (Oh = 0.013) constant. The upstream and downstream interface angles as well as velocity fields surrounding the pinch off location were measured for several distinct modes; e.g. a primary drop separating from the jet, a primary drop splitting in two, and a satellite drop separating from the jet. At the smallest observable scales ( 15 microns), the angles varied with the pinch-off mode. The angles in the splitting drop mode appeared to converge toward values predicted by similarity theory, but angles in the other modes did not. The differences in behavior will be discussed in terms of the local velocity and vorticity fields surrounding each mode. Detailed measurements include centerline velocity and local strain and rotation rate through each pinch-off event. *supported by DOE (DE-FG02-98ER14869)

Milosevic, Ilija; Longmire, Ellen

2003-11-01

136

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

138

Gas-phase flowrate effect on disintegrating cryogenic liquid-jets  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.

1990-01-01

139

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

140

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

141

Influence of operating variables on liquid circulation in a 10.5-m(3) jet loop bioreactor.  

PubMed

A 10.5-m(3) concentric tube jet loop reactor was used to study the influence of the working liquid volume, mean superficial air velocity, operating pressure, downcomer aeration, liquid jet velocity, and two ratios of draft tube/reactor diameter (D(t)/D) on liquid circulation time (T(c)). The experiments were carried out in a water-air system with the use of the acid pulse method. Results showed that circulation time was independent of the working liquid volume over a certain minimum liquid level, whereas downcomer aeration and D(t)/D ratio appeared as amenable parameters to achieve a high degree of control over liquid circulation and mixing efficiency, and to optimize the overall reactor performance. Increasing the operating pressure caused a reduction of the liquid circulation rate. However, ionger residence times of the air bubbles and the higher mass transfer driving force that result at higher pressures improve oxygen utilization. The relationship between T(c) and air load was independent of the operating pressure, provided the correlation is given as a function of the mean superficial air velocity. Neither liquid circulation nor gas holdup were significantly affected by liquid jet velocity. (c) 1995 John Wiley & Sons, Inc. PMID:18623331

García-Salas, S; Flores-Cotera, L B

1995-06-01

142

Ultraviolet vision and foraging in dip and plunge diving birds  

PubMed Central

Many fishes are sensitive to ultraviolet (UV) light and display UV markings during courtship. As UV scatters more than longer wavelengths of light, these signals are only effective at short distances, reducing the risk of detection by swimming predators. Such underwater scattering will be insignificant for dip and plunge diving birds, which prey on fishes just below the water surface. One could therefore expect to find adaptations in the eyes of dip and plunge diving birds that tune colour reception to UV signals. We used a molecular method to survey the colour vision tuning of five families of dip or plunge divers and compared the results with those from sister taxa of other foraging methods. We found evidence of extended UV vision only in gulls (Laridae). Based on available evidence, it is more probable that this trait is associated with their terrestrial foraging habits rather than piscivory. PMID:17148194

Håstad, Olle; Ernstdotter, Emma; Ödeen, Anders

2005-01-01

143

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

144

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

PubMed

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

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

1999-01-01

145

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

NASA Astrophysics Data System (ADS)

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.

Das, Siddhartha; Kumar, Aloke

2014-11-01

146

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

147

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 diss...

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

2013-01-01

148

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

EPA Science Inventory

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

149

Plunging method for Nd : YAG laser cladding with wire feeding  

Microsoft Academic Search

The effects of wire feeding direction and position, cladding time, and cladding speed on the quality of cladding layer for laser cladding with wire feeding are studied. Experiment results indicate that the wire feeding direction and position are important for wire laser cladding. By adopting the correct wire feeding direction and position, the wire can be plunged into the melt

Jae-Do Kim; Yun Peng

2000-01-01

150

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

NASA Astrophysics Data System (ADS)

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 taken at 1 and 100 bar pressures.

Krehl, P.; Warken, D.

1991-04-01

151

Numerical Investigation of Multiple-Impinging Slot Jets in the Gas-Jet Wiping of Liquid Zinc Coatings  

Microsoft Academic Search

A turbulent impinging slot jet is a device which is used in various industrial applications such as glass tempering, heating of complex surfaces, cooling of turbine blades, cooling of electronic devices and in the continuous hot-dip galvanizing line, which is the focus of this study. An impinging slot jet is used to control the zinc film thickness on the sheet

Parsa Tamadonfar

2010-01-01

152

Scattered-light scanner measurements of cryogenic liquid-jet breakup  

NASA Technical Reports Server (NTRS)

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

Ingebo, Robert D.; Buchele, Donald R.

1990-01-01

153

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

NASA Astrophysics Data System (ADS)

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

Soteriou, Marios; Li, Xiaoyi

2011-11-01

154

Terminal Liquid Mass Fractions and Terminal Mean Droplet Sizes in He Free-Jet Expansions  

SciTech Connect

The terminal liquid mass fraction in He free-jet expansions is deduced from time-of-flight measurements using conservation of energy. Both the present results and results from prior measurements are correlated using a scaling parameter which was used previously for correlating droplet size as a function of source conditions. Deduced values of the mass fraction range from 0.047 to 0.42. The terminal mean droplet size is determined using a novel technique based on a size-dependent attenuation of the beam droplets when impacted by electrons. The determined sizes are in agreement with sizes obtained previously by crossing the droplet beam with an atomic beam, confirming the suitability of the present technique, which is relatively simple in comparison with crossing the droplet beam with an atomic beam. Measured values of the terminal velocity of the droplets are compared with values calculated for a model in which real-fluid properties are used for the enthalpy in the source but conversion of heat of condensation into energy of directed motion is neglected. The deviations from perfect-gas behavior in free-jet expansions are shown to be due to real-fluid properties and condensation.

Knuth, E. L. [Chemical and Biomolecular Engineering Department, University of California at Los Angeles, Los Angeles, CA 90095 (United States); Kornilov, O. [Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States); Toennies, J. P. [Max-Planck-Institut fuer Dynamik und Selbstorganisation, Bunsenstrasse 10, 37073 Goettingen (Germany)

2011-05-20

155

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

156

High-power liquid-lithium jet target for neutron production  

SciTech Connect

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 {sup 7}Li(p,n){sup 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{sup 3}) with fast transport. The target was designed based on a thermal model, accompanied by a detailed calculation of the {sup 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{sup 2} and volume power density of ?2 MW/cm{sup 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.

Halfon, S.; Feinberg, G. [Soreq NRC, Yavne 81800 (Israel) [Soreq NRC, Yavne 81800 (Israel); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Arenshtam, A.; Kijel, D.; Berkovits, D.; Eliyahu, I.; Hazenshprung, N.; Mardor, I.; Nagler, A.; Shimel, G.; Silverman, I. [Soreq NRC, Yavne 81800 (Israel)] [Soreq NRC, Yavne 81800 (Israel); Paul, M.; Friedman, M.; Tessler, M. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)] [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel)

2013-12-15

157

A ballistic compressor-based experiment for the visualization of liquid propellant jet combustion above 100 MPa  

NASA Astrophysics Data System (ADS)

This paper describes the components and operation of an experimental setup for the visualization of liquid propellant (LP) jet combustion at pressures above 100 MPa. The apparatus consists of an in-line ballistic compressor and LP injector. The ballistic compressor, based on a modified 76 mm gun, provides high-pressure (ca. 55 MPa) clear hot gas for the jet ignition. A piston (projectile) is fired toward a test chamber beyond the barrel's end, and its rebound is arrested in a transition section that seals the test chamber to the barrel. The LP jet is injected once the piston is restrained, and combustion of the jet further elevates the pressure. At a preset pressure, a disc in the piston ruptures and the combustion gas vents sonically into the barrel. If a monopropellant is used, the jet injection-combustion process then resembles liquid rocket combustion but at very high pressures (ca. 140 MPa). This paper discusses the ballistics of the compression and compares experimental results to those predicted by a numerical model of the apparatus. Experimentally, a pressure of 70 MPa was achieved upon a 12.5 volumetric compression factor by firing a 10 kg piston into 1.04 MPa argon using a charge of 75 g of small-grain M1 propellant.

Birk, A.; Kooker, D. E.

158

Structured electrosprays: A new technique to generate coaxial jets of immiscible liquids with diameters in the micro and nano-metric range  

Microsoft Academic Search

Structured Taylor cones where an electrified meniscus surrounds another one can be obtained if two immiscible liquids (or poorly miscible) are injected at appropriate flow rates through two concentric electrified needles (1). A liquid filament issues from the vertex of each of the two menisci in such a way that a jet with two co-flowing immiscible liquids is emitted from

Ignacio G. Loscertales; Antonio Barrero; Raul Cortijo; Ismael Guerrero

2001-01-01

159

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.

160

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.

161

Nonlinear viscous liquid jets from a rotating orifice E.I. PARAU2, S.P DECENT1, M.J.H. SIMMONS3, D.C.Y. WONG3,  

E-print Network

Nonlinear viscous liquid jets from a rotating orifice E.I. PARAU2, S.P DECENT1, M.J.H. SIMMONS3, D@uea.ac.uk,decentsp@for.mat.bham.ac.uk Abstract. A liquid jet follows a curved trajectory when the orifice from which the jet emerges is rotating

Parau, Emilian I.

162

Assessment of disintegration of rapidly disintegrating tablets by a visiometric liquid jet-mediated disintegration apparatus.  

PubMed

The aim of this study was to develop a responsive disintegration test apparatus that is particularly suitable for rapidly disintegrating tablets (RDTs). The designed RDT disintegration apparatus consisted of disintegration compartment, stereomicroscope and high speed video camera. Computational fluid dynamics (CFD) was used to simulate 3 different designs of the compartment and to predict velocity and pressure patterns inside the compartment. The CFD preprocessor established the compartment models and the CFD solver determined the numerical solutions of the governing equations that described disintegration medium flow. Simulation was validated by good agreement between CFD and experimental results. Based on the results, the most suitable disintegration compartment was selected. Six types of commercial RDTs were used and disintegration times of these tablets were determined using the designed RDT disintegration apparatus and the USP disintegration apparatus. The results obtained using the designed apparatus correlated well to those obtained by the USP apparatus. Thus, the applied CFD approach had the potential to predict the fluid hydrodynamics for the design of optimal disintegration apparatus. The designed visiometric liquid jet-mediated disintegration apparatus for RDT provided efficient and precise determination of very short disintegration times of rapidly disintegrating dosage forms. PMID:22985772

Desai, Parind M; Liew, Celine V; Heng, Paul W S

2013-02-14

163

Image analysis of jet structure on electrospinning from free liquid surface  

SciTech Connect

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

Kula, Jiri, E-mail: jiri.kula@tul.cz; Linka, Ales, E-mail: ales.linka@tul.cz; Tunak, Maros, E-mail: maros.tunak@tul.cz [Department of Textile Evaluation, Faculty of Textile Engineering, Technical University of Liberec, Studentska 2, 461 17 Liberec (Czech Republic); Lukas, David, E-mail: david.lukas@tul.cz [Department of Nonwoven and Nanofibrous Materials, Faculty of Textile Engineering, Technical University of Liberec, Studentska 2, 461 17 Liberec (Czech Republic); Centre for Nanomaterials Advanced Technologies and Innovation, Technical University of Liberec, Studentska 2, 461 17 Liberec (Czech Republic)

2014-06-16

164

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

165

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

Microsoft Academic Search

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

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

2005-01-01

166

Bouncing jet: A Newtonian liquid rebounding off a free surface Matthew Thrasher,* Sunghwan Jung,  

E-print Network

of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from the bath, and the relative motion replenishes the film of air. Jets with one or two bounces are stable processing, such as pouring and mold casting. They also are critical in the design of bearings 7 , gas

Weeks, Eric R.

167

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

Microsoft Academic Search

There have been different approaches in studying the interaction between plasma and liquid, such as sustained plasmas in contact with liquids and pulsed electric discharge in liquids. Recently, we have discovered that stable plasma can be sustained within a gas cavity maintained inside liquid media. A prototype device with key dimensions in sub-millimeter range were operated successfully in de-ionized water

Weidong Zhu; Jose Lopez; Kurt Becker

2008-01-01

168

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

169

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

170

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

171

A study of liquid boric oxide particle growth rates in a gas stream from a simulated jet engine combustor  

NASA Technical Reports Server (NTRS)

It was experimentally determined that the liquid boric oxide particles leaving a jet engine combustor, burning a boron-containing fuel, will have diameters of 1.0 x 10(exp -5) to 2.0 x 10(exp -5) centimeter. For this size range the particle heat-transfer and drag coefficients are essentially infinite. The results may be applied to any boron-containing fuel. Equations are developed that enable the calculation of the particle size-time history. A study of boric oxide deposition mechanisms is included, and suggestions for decreading deposition rates given.

Setze, Paul C

1957-01-01

172

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

SciTech Connect

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

Shumway, R.W.

1997-05-01

173

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

174

Advanced Liquid Cooling for a Traction Drive Inverter Using Jet Impingement and Microfinned Enhanced Surfaces: Preprint  

SciTech Connect

Jet impingement on plain and micro-finned enhanced surfaces was compared to a traditional channel flow configuration. The jets provide localized cooling to areas heated by the insulated-gate bipolar transistor and diode devices. Enhanced microfinned surfaces increase surface area and thermal performance. Using lighter materials and designing the fluid path to manage pressure losses increases overall performance while reducing weight, volume, and cost. Powering four diodes in the center power module of the inverter and computational fluid dynamics (CFD) modeling was used to characterize the baseline as well as jet-impingement-based heat exchangers. CFD modeling showed the thermal performance improvements should hold for a fully powered inverter. Increased thermal performance was observed for the jet-impingement configurations when tested at full inverter power (40 to 100 kW output power) on a dynamometer. The reliability of the jets and enhanced surfaces over time was also investigated. Experimentally, the junction-to- coolant thermal resistance was reduced by up to 12.5% for jet impingement on enhanced surfaces s compared to the baseline channel flow configuration. Base plate-to-coolant (convective) resistance was reduced by up to 37.0% for the jet-based configuration compared to the baseline, suggesting that while improvements to the cooling side reduce overall resistance, reducing the passive stack resistance may contribute to lowering overall junction-to-coolant resistance. Full inverter power testing showed reduced thermal resistance from the middle of the module baseplate to coolant of up to 16.5%. Between the improvement in thermal performance and pumping power, the coefficient of performance improved by up to 13% for the jet-based configuration.

Waye, S. K.; Narumanchi, S.; Mihalic, M.; Moreno, G.; Bennion, K.; Jeffers, J.

2014-08-01

175

Characteristics of impact-driven high-speed liquid jets in water  

NASA Astrophysics Data System (ADS)

This paper describes a preliminary investigation of the characteristics of high-speed water jets injected into water from an orifice. The high-speed jets were generated by the impact of a projectile launched by a horizontal single-stage powder gun and submerged in a water test chamber. The ensuing impact-driven high-speed water jets in the water were visualized by the shadowgraph technique, and the images were recorded by a high-speed digital video camera. The processes following such jet injection into water, the jet-induced shock waves, shock wave propagation, the bubble behavior, bubble collapse-induced rebound shock waves and bubble cloud re-generation were observed. Peak over-pressures of about 24 and 35 GPa measured by a Polyvinylidence difluoride (PVDF) piezoelectric film pressure sensor were generated by the jet impingement and the bubble impingement, respectively. The peak over-pressure was found to decrease exponentially as the stand-off distance between the PVDF pressure sensor and the nozzle exit increases.

Matthujak, A.; Kasamnimitporn, C.; Sittiwong, W.; Pianthong, K.; Takayama, K.; Milton, B. E.

2013-03-01

176

Visualization of laser-induced liquid micro-jet disintegration by means of high-speed video stroboscopy  

NASA Astrophysics Data System (ADS)

In the present paper we describe a novel approach to monitor and to investigate laser induced liquid water jet disintegration in air and in vacuum. The features of liquid beam disintegration in vacuum are of importance for pulsed laser induced liquid beam desorption mass spectrometry and micro-calorimetry. Due to the small liquid beam diameter of 12-15 ?m, its high speed of 50-100 m/s, and a total event duration of a less than a few microseconds only, the microscopic visualization of the jet disintegration was a challenging task. Good quality video sequences have been recorded with a high-speed video stroboscope system running in the back illumination mode. The light pulses were synchronized carefully with the shutter circuit of the stroboscope camera and the IR-laser pulses. With a continuously changing time delay between the desorption laser pulses and the shutter opening a slow-motion effect has been achieved. The delay was changed in steps of 25 ns which corresponds to an equivalent framing speed of about 40,000,000 fps. With a high-brightness light emitting diode (LED) as a light source an exposure time of about 200 ns an effective time resolution of several hundred nanoseconds could be achieved. Using a pulsed Nd:YAG laser instead, the exposure time and time resolution could be reduced down to about 10 ns and 25 ns, respectively. Due to the well known speckle problem when using coherent light sources for illumination we have finally used a Nd:YAG laser excited dye solution of Rhodamine 6G (10-3 M) in methanol solution in a quartz cuvette placed in front of the liquid beam keeping the short exposure time of about 10 ns. In this nearly speckle free visualization mode the real-time slow-motion imaging of the jet disintegration and the study of the desorption process has been made possible with a time resolution of 25 ns (currently limited by the phase shifter steps) and an exposure time of ~10 ns only. It has been found that the laser induced desorption is so fast that the measurement in the gas phase represents a "snapshot" of the situation (structure, complexation, interaction) in solution. The new desorption technique enables very promising studies of the function, structure and interaction of biopolymers in their natural environment.

Stasicki, Boleslaw; Charvat, Ales; Faubel, Manfred; Abel, Bernd

2005-03-01

177

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

SciTech Connect

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

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

2012-07-11

178

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

179

Liquid Fuel Emulsion Jet-in-Crossflow Penetration and Dispersion Under High Pressure Conditions  

NASA Astrophysics Data System (ADS)

The current work focuses on the jet-in-crossflow penetration and dispersion behavior of water-in-oil emulsions in a high pressure environment. Both fuel injection strategies of using a water-in-oil emulsion and a jet-in-crossflow have demonstrated unique benefits in improving gas turbine performance from an emissions and efficiency standpoint. A jet-in-crossflow is very practical for use in gas turbine engines, rocket propulsion, and aircraft engines since it utilizes already available crossflow air to atomize fuel. Injecting water into a combustion chamber in the form of a water-in-oil emulsion allows for pollutant emissions reduction while reducing efficiency loses that may result from using a separate water or steam injection circuit. Dispersion effects on oil droplets are expected, therefore investigating the distribution of both oil and water droplets in the crossflow is an objective in this work. Understanding the synchronization and injection behavior of the two strategies is of key interest due to their combined benefits. A water-to-oil ratio and an ambient pressure parameter are developed for emulsion jet-in-crossflow trajectories. To this end, a total of 24 emulsion jet-in-crossflow tests were performed with varying ambient pressures of 2-8 atm and momentum flux ratios of 50, 85, and 120. Sobel edge filtering was applied to each averaged image obtained from a high speed video of each test case. Averaged and filtered images were used to resolve top and bottom edges of the trajectory in addition to the overall peak intensity up to 40 mm downstream of the injection point. An optimized correlation was established and found to differ from literature based correlations obtained under atmospheric pressure conditions. Overall it was found that additional parameters were not necessary for the top edge and peak intensity correlations, but a need for a unique emulsion bottom edge and width trajectory correlation was recognized. In addition to investigating emulsion jet-in-crossflow trajectory correlations, a unique Dual Planar Laser Induced Fluorescence (Dual-PLIF) method was applied for the first time on emulsions at elevated pressure conditions. From the Dual-PLIF results, qualitative observations provided insight into the unique dispersion of oil and water concentrations within a cross-sectional plane down stream of the jet-in-crossflow injection.

Gomez, Guillermo Andres

180

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

Microsoft Academic Search

The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently

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

2006-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

182

Impingement heat transfer and recovery effect with submerged jets of large Prandtl number liquid—II. Initially laminar confined slot jets  

Microsoft Academic Search

Local measurements were made to determine recovery factors and heat transfer coefficients resulting from the impingement of transformer oil jets issuing from tiny slot nozzles of 0.091, 0.146, and 0.234 mm in width. This study focused on initially laminar jets in the range of jet Reynolds number between 55 and 415, and fluid Prandtl number between 200 and 270. Lateral

T. Gomi; Y. ZHUANG; S. C. LEE

1997-01-01

183

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

Microsoft Academic Search

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

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

1994-01-01

184

Dynamic response to acoustic perturbation of an atomizing coaxial jet in a liquid rocket engine  

Microsoft Academic Search

A study of the acoustic perturbations on the atomization of a coaxial gas\\/liquid rocket engine injector is being carried out. A pair of compression drivers are used to excite a transverse acoustic field at strengths of up to 155.6 dB in an experimental rocket combustion chamber. Ethanol and oxygen enriched air are used as fuel and oxidizer. Chamber pressure is

A. Ghafourian; R. McGuffin; S. Mahalingam; J. W. Daily

1993-01-01

185

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

186

Generation of thrust and lift with airfoils in plunging and pitching motion  

NASA Astrophysics Data System (ADS)

We present fully resolved Direct Numerical Simulations of 2D flow over a moving airfoil, using an in-house code that solves the Navier-Stokes equations of the incompressible flow with an Immersed Boundary Method. A combination of sinusoidal plunging and pitching motions is imposed to the airfoil. Starting from a thrust producing case (Reynolds number, Re = 1000, reduced frequency, k = 1.41, plunging amplitude h0/c = 1, pitching amplitude ?0 = 30°, phase shift phi = 90°), we increase the mean pitching angle (in order to produce lift) and vary the phase shift between pitching and plunging (to optimize the direction and magnitude of the net force on the airfoil). These cases are discussed in terms of their lift coefficient, thrust coefficient and propulsive efficiency.

Moriche, M.; Flores, O.; García-Villalba, M.

2015-01-01

187

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

188

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

NASA Astrophysics Data System (ADS)

This paper considers the analysis of transient heating of a hemispherical solid plate of finite thickness during impingement 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. Calculations were done for Reynolds number ( Re) ranging from 500 to 1,500 and dimensionless plate thicknesses to nozzle diameter ratio ( b/ d n) from 0.083 to 1.5. Results are presented for local and average Nusselt number using water as the coolant and various solid materials such as silicon, constantan, and copper. It was detected that increasing the Reynolds number decreases the time for the plate to achieve the steady-state condition. Also, a higher Reynolds number increases the Nusselt number. Hemispherical plate materials with higher thermal conductivity maintain lower temperature non-uniformity at the solid-fluid interface. Increasing the plate thickness decreases the maximum temperature in the solid and increases the time to reach the steady-state condition.

Rahman, Muhammad M.; Hernandez, Cesar F.

2011-01-01

189

Feasibility study of total reflection X-ray fluorescence analysis using a liquid metal jet X-ray tube  

NASA Astrophysics Data System (ADS)

Total reflection X-ray spectroscopy (TXRF) is a powerful analytical technique for qualitative and quantitative analysis of trace and ultratrace elements in a sample with lower limits of detection (LLDs) of pg/g to ng/g in concentration and absolute high fg levels are attainable. Several X-ray sources, from low power (few W), 18 kW rotating anodes to synchrotron radiation, are in use for the excitation and lead accordingly to their photon flux delivered on the sample the detection limits specified. Not only the power, but also the brilliance and focal shape are of importance for TXRF. A microfocus of 50-100 ?m spot size or the line focus of diffraction tubes is best suited. Excillum developed a new approach in the design of a source: the liquid metal jet anode. In this paper the results achieved with this source are described. A versatile TXRF spectrometer with vacuum chamber designed at Atominstitut was used for the experiments. A multilayer monochromator selecting the intensive Ga-K? radiation was taken and the beam was collimated by 50 ?m slits. Excellent results regarding geometric beam stability, high fluorescence intensities and low background were achieved leading to detection limits in the high fg range for Ni. A 100 mm2 silicon drift detector (SDD) collimated to 80 mm2 was used to collect the fluorescence radiation. The results from measurements on single element samples are presented.

Maderitsch, A.; Smolek, S.; Wobrauschek, P.; Streli, C.; Takman, P.

2014-09-01

190

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

191

Ejectors and jet pumps: Computer program for design and performance for liquid flow  

NASA Astrophysics Data System (ADS)

ESDU 93022 introduces a Fortran program (ESDUpac A9322) for ejectors in which the primary and secondary flows are of non-reacting miscible liquids. Inlet conditions for both primary and secondary flows can be either constant pressure or provided by a pump. In the latter case it is assumed that the head can be expressed as a quadratic in pump speed and flow rate. Two procedures are provided: a Design Procedure and Performance Prediction. For the first the input is a selection of entry and required exit pressures and flow rates, together with estimates of loss coefficients in the primary and secondary nozzles, mixing duct and diffuser. The program will optimize the ejector, calculating the primary nozzle, secondary inlet and ejector exit dimensions. For the second case, the ejector dimensions are input together with the loss factors again and a range of entry flow conditions and the program will calculate flow conditions throughout the ejector and at exit. The equations on which the program is based are fully specified, the input format required is set out in clear tables, and two worked examples illustrate the use of both procedures. The program is provided on disc (uncompiled) in the software volume, and compiled within ESDUview, a user-friendly shell running under MS-DOS that prompts on screen for input data.

1993-12-01

192

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

193

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

194

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, José M.; Katopodis, Christos; Pinheiro, António; Ferreira, Maria T.

2013-01-01

195

Elemental Water Impact Test: Phase 3 Plunge Depth of a 36-Inch Aluminum Tank Head  

NASA Technical Reports Server (NTRS)

Spacecraft are being designed based on LS-DYNA water landing simulations. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 3 featured a composite tank head that was tested at a range of heights to verify the ability to predict structural failure of composites. To support planning for Phase 3, a test series was conducted with an aluminum tank head dropped from heights of 2, 6, 10, and 12 feet to verify that the test article would not impact the bottom of the test pool. This report focuses on the comparisons of the measured plunge depths to LS-DYNA predictions. The results for the tank head model demonstrated the following. 1. LS-DYNA provides accurate predictions for peak accelerations. 2. LS-DYNA consistently under-predicts plunge depth. An allowance of at least 20% should be added to the LS-DYNA predictions. 3. The LS-DYNA predictions for plunge depth are relatively insensitive to the fluid-structure coupling stiffness.

Vassilakos, Gregory J.

2014-01-01

196

Pool-type fishways: two different morpho-ecological cyprinid species facing plunging and streaming flows.  

PubMed

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, José M; Katopodis, Christos; Pinheiro, António; Ferreira, Maria T

2013-01-01

197

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

NASA Astrophysics Data System (ADS)

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

Means, Steven L.; Heitmeyer, Richard M.

2002-08-01

198

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.

199

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.

Gene Feldman

200

Numerical simulation of a plunging flexible hydrofoil and its experimental validation  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

201

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

202

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

203

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

204

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

205

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

206

Jets from Imploding Bubbles  

Microsoft Academic Search

BOWDEN has suggested that micro-Munro jets may play a part in the initiation of non-homogeneous explosive systems1. In addition, he and Brunton have shown that such jets can be formed by impacting a vessel containing a liquid with a hemispheric cavity located on its surface2. In an investigation of possible mechanisms for the initiation and propagation of low-velocity detonations in

Richard W. Watson; Frank C. Gibson

1964-01-01

207

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

208

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

PubMed Central

Australasian gannets (Morus serrator), like many other seabird species, locate pelagic prey from the air and perform rapid plunge dives for their capture. Prey are captured underwater either in the momentum (M) phase of the dive while descending through the water column, or the wing flapping (WF) phase while moving, using the wings for propulsion. Detection of prey from the air is clearly visually guided, but it remains unknown whether plunge diving birds also use vision in the underwater phase of the dive. Here we address the question of whether gannets are capable of visually accommodating in the transition from aerial to aquatic vision, and analyse underwater video footage for evidence that gannets use vision in the aquatic phases of hunting. Photokeratometry and infrared video photorefraction revealed that, immediately upon submergence of the head, gannet eyes accommodate and overcome the loss of greater than 45 D (dioptres) of corneal refractive power which occurs in the transition between air and water. Analyses of underwater video showed the highest prey capture rates during WF phase when gannets actively pursue individual fish, a behaviour that very likely involves visual guidance, following the transition after the plunge dive's M phase. This is to our knowledge the first demonstration of the capacity for visual accommodation underwater in a plunge diving bird while capturing submerged prey detected from the air. PMID:22874749

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

2012-01-01

209

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

210

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

211

Numerical investigation of the vertical plunging force of a spherical intruder into a prefluidized granular bed  

NASA Astrophysics Data System (ADS)

The plunging of a large intruder sphere into a prefluidized granular bed with various constant velocities and various sphere diameters is investigated using a state-of-the-art hybrid discrete particle and immersed boundary method, in which both the gas-induced drag force and the contact force exerted on the intruder can be investigated separately. We investigate low velocities, where velocity dependent effects first begin to appear. The results show a concave-to-convex dependence of the plunging force as a function of intruder depth. In the concave region the force fits to a power law with an exponent around 1.3, which is in good agreement with existing experimental observations. Our simulation results further show that the force exerted on the frontal hemisphere of the intruder is dominant. At larger intruder velocities, friction with the granular medium causes a velocity-dependent drag force. As long as the granular particles have not yet closed the gap behind the intruder, this drag force is independent of the actual intruder depth. In this regime, the drag force experienced by intruders of different diameter moving at different velocities all fall onto a single master curve if plotted against the Reynolds number, using a single value for the effective viscosity of the granular medium. This master curve corresponds well to the Schiller-Naumann correlation for the drag force between a sphere and a Newtonian fluid. After the gap behind the intruder has closed, the drag force increases not only with velocity but also with depth. We attribute this to the effect of increasing hydrostatic particle pressure in the granular medium, leading to an increase in effective viscosity.

Xu, Y.; Padding, J. T.; Kuipers, J. A. M.

2014-12-01

212

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

213

Modeling flow and residence time distribution in an industrial-scale reactor with a plunging jet inlet and optional agitation  

Microsoft Academic Search

The quantified residence time distribution (RTD) provides a numerical characterization of mixing in a reactor, thus allowing the process engineer to better understand mixing performance of the reactor. Many reactors are mixing-limited and\\/or mass-transfer limited and micro-mixing can be the critical element in contrast to RTD which addresses the macro-mixing. This paper discusses computational and experimental studies to investigate flow

Hua Bai; Amber Stephenson; Jorge Jimenez; Dennis Jewell; Paul Gillis

2008-01-01

214

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

E-print Network

We study a liquid jet that breaks up into drops in an external co-flowing liquid inside a confining microfluidic geometry. The jet breakup can occur right after the nozzle in a phenomenon named dripping or through the generation of a liquid jet that breaks up a long distance from the nozzle, which is called jetting. Traditionally, these two regimes have been considered to reflect the existence of two kinds of spatiotemporal instabilities of a fluid jet, the dripping regime corresponding to an absolutely unstable jet and the jetting regime to a convectively unstable jet. Here, we present quantitative measurements of the dripping and jetting regimes, both in an unforced and a forced state, and compare these measurements with recent theoretical studies of spatiotemporal instability of a confined liquid jet in a co-flowing liquid. In the unforced state, the frequency of oscillation and breakup of the liquid jet is measured and compared to the theoretical predictions. The dominant frequency of the jet oscillations...

Cordero, María Luisa; Baroud, Charles N

2010-01-01

215

Membrane damage and active but nonculturable state in liquid cultures of Escherichia coli treated with an atmospheric pressure plasma jet.  

PubMed

Electrical discharge plasmas can efficiently inactivate various microorganisms. Inactivation mechanisms caused by plasma, however, are not fully understood because of the complexity of both the plasma and biological systems. We investigated plasma-induced inactivation of Escherichia coli in water and mechanisms by which plasma affects bacterial cell membrane integrity. Atmospheric pressure argon plasma jet generated at ambient air in direct contact with bacterial suspension was used as a plasma source. We determined significantly lower counts of E. coli after treatment by plasma when they were assayed using a conventional cultivation technique than using a fluorescence-based LIVE/DEAD staining method, which indicated that bacteria may have entered the viable-but-nonculturable state (VBNC). We did not achieve resuscitation of these non-culturable cells, however, we detected their metabolic activity through the analysis of cellular mRNA, which suggests that cells may have been rather in the active-but-nonculturable state (ABNC). We hypothesize that peroxidation of cell membrane lipids by the reactive species produced by plasma was an important pathway of bacterial inactivation. Amount of malondialdehyde and membrane permeability of E. coli to propidium iodide increased with increasing bacterial inactivation by plasma. Membrane damage was also demonstrated by detection of free DNA in plasma-treated water. PMID:25212700

Dolezalova, Eva; Lukes, Petr

2014-08-29

216

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

217

Determination of guanine and adenine by high-performance liquid chromatography with a self-fabricated wall-jet/thin-layer electrochemical detector at a glassy carbon electrode.  

PubMed

A sensitive wall-jet/thin-layer amperometric electrochemical detector (ECD) coupled to high-performance liquid chromatography (HPLC) was developed for simultaneous determination of guanine (G) and adenine (A). The analytes were detected at a glassy carbon electrode (GCE) and the HPLC-ECD calibration curves showed good linearity (R(2)>0.997) under optimized conditions. Limits of detection for G and A are 0.6nM and 1.4nM (S/N=3), respectively, which are lower than those obtained with an UV-vis detector and a commercial electrochemical detector. We have successfully applied this HPLC-ECD to assess the contents of G and A in hydrochloric acid-digested calf thymus double-stranded DNA. In addition, we compared in detail the analysis of G and A by cyclic voltammetry (CV) and by the HPLC-ECD system on both bare GCE and electroreduced graphene oxide (ERGO) modified GCE. We found that the adsorption of G and A on the electrode surfaces can vary their anodic CV peaks and the competitive adsorption of G and A on the limited sites of the electrode surfaces can cause crosstalk effects on their anodic CV peak signals, but the HPLC-ECD system is insensitive to such electrode-adsorption and can give more reliable analytical results. PMID:25618679

Zhou, Yaping; Yan, Hongling; Xie, Qingji; Yao, Shouzhuo

2015-03-01

218

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

NASA Technical Reports Server (NTRS)

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

Bennett, Robert M.

2000-01-01

219

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

SciTech Connect

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

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

2008-09-15

220

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

SciTech Connect

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

Weggel, R.J.

1998-06-01

221

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

222

Is there a clinical benefit with a smooth compensator design compared with a plunged compensator design for passive scattered protons?  

PubMed

In proton therapy, passive scattered proton plans use compensators to conform the dose to the distal surface of the planning volume. These devices are custom made from acrylic or wax for each treatment field using either a plunge-drilled or smooth-milled compensator design. The purpose of this study was to investigate if there is a clinical benefit of generating passive scattered proton radiation treatment plans with the smooth compensator design. We generated 4 plans with different techniques using the smooth compensators. We chose 5 sites and 5 patients for each site for the range of dosimetric effects to show adequate sample. The plans were compared and evaluated using multicriteria (MCA) plan quality metrics for plan assessment and comparison using the Quality Reports [EMR] technology by Canis Lupus LLC. The average absolute difference for dosimetric metrics from the plunged-depth plan ranged from -4.7 to +3.0 and the average absolute performance results ranged from -6.6% to +3%. The manually edited smooth compensator plan yielded the best dosimetric metric, +3.0, and performance, + 3.0% compared to the plunged-depth plan. It was also superior to the other smooth compensator plans. Our results indicate that there are multiple approaches to achieve plans with smooth compensators similar to the plunged-depth plans. The smooth compensators with manual compensator edits yielded equal or better target coverage and normal tissue (NT) doses compared with the other smooth compensator techniques. Further studies are under investigation to evaluate the robustness of the smooth compensator design. PMID:25263491

Tabibian, Art A; Powers, Adam; Dolormente, Keith; Oommen, Sneha; Tiwari, Akhil; Palmer, Matt; Zhu, Xiaorong R; Li, Heng; Sahoo, Narayan; Wisdom, Paul; Velasco, Kyle; Erhart, Kevin; Stanley, Henry; Nguyen, Bao-Ngoc T

2015-01-01

223

Experimental investigation on the behavior of a microdroplet jet  

Microsoft Academic Search

This paper deals with the generation, measurement and control of micro liquid droplet jet in water. In connection with the development of a lipid membrane biosensor device for underground water pollution, a method of working liquid transportation by micro droplet jet has been proposed. The generation and the behavior of micro droplet jet have been investigated by the method of

Masaru Ishizuka; Shinji Nakagawa; Yoshio Ishimori; Koichiro Kawano

2004-01-01

224

Figure 2: The mercury jet target geometry. The proton beam and mercury jet cross at z=-37.5 cm.  

E-print Network

Figure 2: The mercury jet target geometry. The proton beam and mercury jet cross at z=-37.5 cm. Figure 3: The layout of multiple proton beam entry directions relative to mercury jet at z=-75 cm. A PION of a free liquid mercury jet with an intense proton beam. We study the variation of meson production

McDonald, Kirk

225

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

NASA Astrophysics Data System (ADS)

We study a liquid jet that breaks up into drops in an external co-flowing liquid inside a confining microfluidic geometry. The jet breakup can occur right after the nozzle in a phenomenon named dripping or through the generation of a liquid jet that breaks up a long distance from the nozzle, which is called jetting. Traditionally, these two regimes have been considered to reflect the existence of two kinds of spatiotemporal instabilities of a fluid jet, the dripping regime corresponding to an absolutely unstable jet and the jetting regime to a convectively unstable jet. Here, we present quantitative measurements of the dripping and jetting regimes, both in an unforced and a forced state, and compare these measurements with recent theoretical studies of spatiotemporal instability of a confined liquid jet in a co-flowing liquid. In the unforced state, the frequency of oscillation and breakup of the liquid jet is measured and compared to the theoretical predictions. The dominant frequency of the jet oscillations as a function of the inner flow rate agrees qualitatively with the theoretical predictions in the jetting regime but not in the dripping regime. In the forced state, achieved with periodic laser heating, the dripping regime is found to be insensitive to the perturbation and the frequency of drop formation remains unaltered. The jetting regime, on the contrary, amplifies the externally imposed frequency, which translates into the formation of drops at the frequency imposed by the external forcing. In conclusion, the dripping and jetting regimes are found to exhibit the main features of absolutely and convectively unstable flows, respectively, but the frequency selection in the dripping regime is not ruled by the absolute frequency predicted by the stability analysis.

Cordero, María Luisa; Gallaire, François; Baroud, Charles N.

2011-09-01

226

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

227

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

228

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

229

Unsteady Aerodynamic Testing Using the Dynamic Plunge Pitch and Roll Model Mount  

NASA Technical Reports Server (NTRS)

A final report on the DyPPiR tests that were run are presented. Essentially it consists of two parts, a description of the data reduction techniques and the results. The data reduction techniques include three methods that were considered: 1) signal processing of wind on - wind off data; 2) using wind on data in conjunction with accelerometer measurements; and 3) using a dynamic model of the sting to predict the sting oscillations and determining the aerodynamic inputs using an optimization process. After trying all three, we ended up using method 1, mainly because of its simplicity and our confidence in its accuracy. The results section consists of time history plots of the input variables (angle of attack, roll angle, and/or plunge position) and the corresponding time histories of the output variables, C(sub L), C(sub D), C(sub m), C(sub l), C(sub m), C(sub n). Also included are some phase plots of one or more of the output variable vs. an input variable. Typically of interest are pitch moment coefficient vs. angle of attack for an oscillatory motion where the hysteresis loops can be observed. These plots are useful to determine the "more interesting" cases. Samples of the data as it appears on the disk are presented at the end of the report. The last maneuver, a rolling pull up, is indicative of the unique capabilities of the DyPPiR, allowing combinations of motions to be exercised at the same time.

Lutze, Frederick H.; Fan, Yigang

1999-01-01

230

Mathematical modeling and experimental investigations of oxygen-methane fuel combustion at coaxial-jet supply into the combustion chamber of liquid-propellant rocket engine  

Microsoft Academic Search

The numerical results are presented for the case of coaxial-jet supply at the different ratio of mass component velocities\\u000a at the combustion chamber inlet with the constant and variable relationship of oxygen-methane components. The experimental\\u000a investigations of coaxial-jet mixing elements as part of the model setup chamber operating on corrosive producer gas and gaseous\\u000a methane were carried out. A qualitative

V. R. Rubinskii; S. P. Khrisanfov; V. Yu. Klimov; A. V. Kretinin

2010-01-01

231

Destruction regimes of Sun-skimming and Sun-plunging comets  

NASA Astrophysics Data System (ADS)

We establish and model destruction regimes for close sun-grazers, i.e. comets of small enough perihelia (q ? a few R_?) and large enough mass (M_o ? 10^{13} g) to reach the inner solar corona or below. These can be divided into sun-skimming and sun-plunging according to whether their M_o,q values confine them to atmospheric densities n ? 10^{14}cm^{-3} where mass loss is dominated by insolative sublimation, or let them reach n? 10^{14}cm^{-3} where hydrodynamic interactions with the dense chromosphere take over (bow-shock-heated ablative mass loss, ram pressure pancaking and deceleration). Being rare, no sun-plungers have yet been detected but they are of potentially great interest. Recent years have seen the first direct monitoring of three sun-skimmers in the low corona by SDO at EUV wavelengths. Both sun-plungers and sun-skimmers offer novel diagnostics of both cometary and solar conditions. We show that, due to their much higher speeds than planetary impacts, sun-plungers are likely dominated by pancaking and ablative mass-loss, rather than deceleration, even for quite inefficient bow-shock heat transfer, but we obtain solutions for ablation- and deceleration-dominated, and for intermediate, cases. All involve rapid local deposition of nucleus kinetic energy and momentum within a few 100 km near the photosphere. This occurs at atmospheric density n_{peak}(cm^{-3})?3×10^{16}(X?_{-2}^3M_{15})^{1/2} for incident mass M_o=10^{15}M_{15} g, incident angle ? = cos^{-1}(10^{-2}?_{-2}) to the vertical, and parameter X ranges from 0.001 up to 1. Break-up into Y fragments reduces n_{peak} by a factor ? Y^{-1/3}. This deposition will drive hot rising 'airburst' plumes and internal helioseismic waves similar to magnetic flare effects. In the normal ablation-dominated case (small X) the hot airburst will exhibit essentially cometary abundances (metallicity Gt; solar). Though sun-skimmer nuclei are vaporized by 5800 K (? 0.6 eV/photon) photospheric sunlight, their dissociation, ionization and heating up to EUV temperatures (10-100 eV) have to involve chromospheric EUV (10 eV/photon), 2 MK coronal thermal conduction (200 eV/electron) and conversion of nucleus kinetic energy (2 keV/nucleon). Coronal heat flux may be important in small sun-skimmers with tenuous comae and tails but kinetic energy conversion must dominate in large ones like Lovejoy 2011.

Brown, J.; Carlson, R.; Toner, M.

2014-07-01

232

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

PubMed

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

Frederick, Jennifer

2010-09-01

233

AN INVESTIGATION OF THE REACTION BETWEEN HOT MOLYBDENUM AND LIQUID OXYGEN. Final Report  

Microsoft Academic Search

Cylindrical molybodenum samples 0.05 in. diameter by 5 in. long, 0.10 ; in. diameter by 5 in. long, 0.375 in. diameter by 4 in. long, and 1.75 in. ; diameter by 3 in. long were heated in inert atmospheres to various temperatures ; up to 2290 deg F and plunged into liquid oxygen. All samples heated to ; temperatures below

T. C. Goodale; B. Ragent; A. Samuels; N. R. Wallace

1958-01-01

234

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

235

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

236

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

237

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

238

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

2012-08-17

239

Stellar jets  

E-print Network

With a goal of understanding the conditions under which jets might be produced in novae and related objects, I consider the conditions under which jets are produced from other classes of accreting compact objects. I give an overview of accretion disk spectral states, including a discussion of in which states these jets are seen. I highlight the differences between neutron stars and black holes, which may help give us insights about when and how the presence of a solid surface may help or inhibit jet production.

Thomas J. Maccarone

2008-05-23

240

Liquid atomization in supersonic flows  

NASA Astrophysics Data System (ADS)

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

Missoum, Azzedine

241

Synthetic jets  

Microsoft Academic Search

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

Ari Glezer; Michael Amitay

2002-01-01

242

Fluid Mechanics of Liquid-Liquid Systems.  

NASA Astrophysics Data System (ADS)

The detailed hydrodynamics of selected liquid -liquid flow systems are investigated to provide a firm foundation for the rational design of separation processes. The implementation of this objective centers on the development of a robust code to simulate liquid-liquid flows. We have applied this code to the realistic simulation of aspects of the complex fluid mechanical behavior, and developed quantitative insight into the underlying processes involved. The Volume of Fluid (VOF) method is combined with the Continuous Surface Force (CSF) algorithm to provide a numerically stable code capable of solving high Reynolds numbers free surface flows. One of the developments during the testing was an efficient method for solving the Young-Laplace equation describing the shape of the meniscus in a vertical cylinder for a constrained liquid volume. The steady-state region near the nozzle for the laminar flow of a Newtonian liquid jet injected vertically into another immiscible Newtonian liquid is investigated for various Reynolds numbers by solving the axisymmetric transient equations of motion and continuity. The analysis takes into account pressure, viscous, inertial, gravitational, and surface tension forces, and comparison with previous experimental measurements shows good agreement. Comparisons of the present numerical method with the numerical results of previous boundary-layer methods help establish their range of validity. A new approximate equation for the shape of the interface of the steady jet, based on an overall momentum balance, is also developed. The full transient from liquid-liquid jet startup to breakup into drops is also simulated numerically. In comparison with experiment, the results of the present numerical method show a greater sensitivity of the jet length to the Reynolds number than the best predictions of previous linear stability analyses. The formation of drops is investigated at low to high Reynolds numbers before and after jet formation. The numerical simulations are satisfactorily compared with n-heptane/water experiments and previous simplified analyses based on drop formation before and after jetting. Although the program and numerical techniques developed in this dissertation have been used mainly to solve problems involving liquid-liquid jets and drops, many features of more complex and general liquid-liquid contacting systems are explored in the process.

Richards, John Reed

243

Electrohydrodynamic cone-jet bridges: Stability diagram and operating modes  

E-print Network

a nozzle and a liquid pool that were closely separated. There was a stability island for the cone-jet]. For the conventional cone-jet, voltage (V) and flow rate (Q) are the main external control variables, and the Ve boundaries. 2. Experimental setup We adopted a nozzle-to-pool configuration to study the cone-jet bridge (Fig

Chen, Chuan-Hua

244

Effect of the injection-nozzle geometry on the interaction between a gas–liquid jet and a gas–solid fluidized bed  

Microsoft Academic Search

In industrial fluid cokers, bitumen is first mixed with steam in a premixer, and then fed to the atomization nozzle. The objective of this work was to evaluate the impact of both the premixer and the nozzle geometrical configuration on the quality of the liquid–solid contact resulting from injections of liquid into a gas–solid fluidized bed. To assess the quality

Federica Portoghese; Lorenzo Ferrante; Franco Berruti; Cedric Briens; Edward Chan

2010-01-01

245

Bouncing Jets  

NASA Astrophysics Data System (ADS)

Contrary to common intuition, free jets of fluid can ``bounce'' off each other on collision in mid-air, through the effect of a lubricating air film that separates the jets. We have developed a simple experimental setup to stably demonstrate and study the non-coalescence of jets on collision. We present the results of an experimental investigation of oblique collision between two silicone oil jets, supported by a simple analytical explanation. Our focus is on elucidating the role of various physical forces at play such as viscous stresses, capillary force and inertia. A parametric study conducted by varying the nozzle diameter, jet velocity, angle of inclination and fluid viscosity reveals the scaling laws for the quantities involved such as contact time. We observed a transition from bouncing to coalescence with an increase in jet velocity and inclination angle. We propose that a balance between the contact time of jets and the time required for drainage of the trapped air film can provide a criterion for transition from non-coalescence to coalescence.

Wadhwa, Navish; Vlachos, Pavlos; Jung, Sunghwan

2011-11-01

246

Dynamics of impinging nanoscale jets  

NASA Astrophysics Data System (ADS)

We use molecular dynamics simulations to describe the collision of two opposed liquid argon nanojets and examine the subsequent stagnation flow. The streamwise and transverse velocity profiles in the proximity of stagnation point are in agreement with macroscale continuum relations u? = ?x?, v? = - ?y? for impinging laminar streams. Jet exit velocities are highest for non-wetting surfaces and decrease as solid-liquid interactions are enhanced. The work done to produce the nanojet dissipates at jet exits, increasing the local temperature. The fluid temperature is lowered through cooling as jets exit through the nonperiodic boundaries. In comparison, water nanojets have higher exit velocities with relatively lower pressure drops across the reservoir and cavity.

Balasubramanian, Ganesh; Puri, Ishwar K.; Ragab, Saad A.

2010-05-01

247

Experimental study on flow kinematics and impact pressure in liquid sloshing  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2008-10-01

249

Business Jet  

NASA Technical Reports Server (NTRS)

The Citation Jet, developed by Cessna Aircraft Company, Wichita, KS, is the first business jet to employ Langley Research Center's natural laminar flow (NLF) technology. NLF reduces drag and therefore saves fuel by using only the shape of the wing to keep the airflow smooth, or laminar. This reduces friction between the air and wing, and therefore, reduces drag. NASA's Central Industrial Applications Center, Rural Enterprises, Inc., Durant, OK, its Kansas affiliate, and Wichita State University assisted in the technology transfer.

1991-01-01

250

Absolute instability of a viscous hollow jet.  

PubMed

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

Gañán-Calvo, Alfonso M

2007-02-01

251

Absolute instability of a viscous hollow jet  

NASA Astrophysics Data System (ADS)

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

Gañán-Calvo, Alfonso M.

2007-02-01

252

Jet observables without jet algorithms  

E-print Network

We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but ...

Bertolini, Daniele

253

Marangoni flows induced by atmospheric-pressure plasma jets  

NASA Astrophysics Data System (ADS)

We studied the interaction of atmospheric-pressure plasma jets of Ar or air with liquid films of an aliphatic hydrocarbon on moving solid substrates. The hydrodynamic jet-liquid interaction induces a track of lower film thickness. The chemical plasma-surface interaction oxidizes the liquid, leading to a local increase of the surface tension and a self-organized redistribution of the liquid film. We developed a numerical model that qualitatively reproduces the formation, instability and coarsening of the flow patterns observed in the experiments. Monitoring the liquid flow has potential as an in-situ, spatially and temporally resolved, diagnostic tool for the plasma-liquid surface interaction.

Berendsen, C. W. J.; van Veldhuizen, E. M.; Kroesen, G. M. W.; Darhuber, A. A.

2015-01-01

254

Investigation of compound jet electrospray: Particle encapsulation  

NASA Astrophysics Data System (ADS)

Experiments were performed to investigate the effect of surface tension on the particle encapsulation formation in the compound jet electrospray process. The outer liquid used in this study were olive oil and mineral oil; and inner liquids were ethanol, tri-butyl phosphate, ethylene glycol, and triethylene glycol. It was found that the core-shell structured droplets are formed only when the ratio of charge relaxation lengths of the inner and outer jets [i.e., rO*/rI*, where r *=(Q??0/K)1/3, in which ? is the dielectric constant of liquid] is less than 500, and the ratio of inertial breakup lengths of the inner and outer jets [i.e., RO*/RI*, where R *=(?Q2/?)1/3, in which ? and ? are the density and surface tension of liquid, respectively] is less than 0.015. In this work we further studied the effect of inner and outer liquid flow rates on the size of compound droplets using an Aerosizer (TSI model 3220). The parameters affecting the droplet size distribution were obtained. We also observed that the spray current emitted through the compound jet was merely a linear function of the inner jet flow rate. This observation implies that olive oil and mineral oil, as the outer liquids, serve as an electrically insulated layer during the spray process.

Mei, Fan; Chen, Da-Ren

2007-10-01

255

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

256

Experimental study of elliptical jet from sub to supercritical conditions  

SciTech Connect

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 N{sub 2} 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, E-mail: aravind7@iist.ac.in [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)] [Department of Aerospace Engineering, Indian Institute of Space Science and Technology, Trivandrum, Kerala 695547 (India)

2014-04-15

257

Synthetic Jets  

NASA Technical Reports Server (NTRS)

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

Milanovic, Ivana M.

2003-01-01

258

Helium jet dispersion to atmosphere  

NASA Technical Reports Server (NTRS)

On the event of loss of vacuum guard of superinsulated helium dewar, high rate of heat transfer into the tank occurs. The rapid boiling of liquid helium causes the burst disk to rupture at four atmospheres and consequently the helium passes to the atmosphere through vent lines. The gaseous helium forms a vertical buoyant jet as it exits the vent line into a stagnant environment. Characterization of the gaseous jet is achieved by detailed analysis of the axial and radial dependence of the flow parameters.

Khan, Hasna J.

1986-01-01

259

Numerical Simulations of Bouncing Jets  

E-print Network

Bouncing jets are fascinating phenomenons occurring under certain conditions when a jet impinges on a free surface. This effect is observed when the fluid is Newtonian and the jet falls in a bath undergoing a solid motion. It occurs also for non-Newtonian fluids when the jets falls in a vessel at rest containing the same fluid. We investigate numerically the impact of the experimental setting and the rheological properties of the fluid on the onset of the bouncing phenomenon. Our investigations show that the occurrence of a thin lubricating layer of air separating the jet and the rest of the liquid is a key factor for the bouncing of the jet to happen. The numerical technique that is used consists of a projection method for the Navier-Stokes system coupled with a level set formulation for the representation of the interface. The space approximation is done with adaptive finite elements. Adaptive refinement is shown to be very important to capture the thin layer of air that is responsible for the bouncing.

Bonito, Andrea; Lee, Sanghyun

2015-01-01

260

A determination of the external forces required to move the benchmark active controls testing model in pure plunge and pure pitch  

NASA Technical Reports Server (NTRS)

In view of the strong need for a well-documented set of experimental data which is suitable for the validation and/or calibration of modern Computational Fluid Dynamics codes, the Benchmark Models Program was initiated by the Structural Dynamics Division of the NASA Langley Research Center. One of the models in the program, the Benchmark Active Controls Testing Model, consists of a rigid wing of rectangular planform with a NACA 0012 profile and three control surfaces (a trailing-edge control surface, a lower-surface spoiler, and an upper-surface spoiler). The model is affixed to a flexible mount system which allows only plunging and/or pitching motion. An approximate analytical determination of the forces required to move this model, with its control surfaces fixed, in pure plunge and pure pitch at a number of test conditions is included. This provides a good indication of the type of actuator system required to generate the aerodynamic data resulting from pure plunging and pure pitching motion, in which much interest was expressed. The analysis makes use of previously obtained numerical results.

Dcruz, Jonathan

1993-01-01

261

Zero gravity liquid mixer  

NASA Technical Reports Server (NTRS)

An apparatus for mixing liquids under conditions of zero gravity is disclosed. The apparatus is comprised of a closed reservoir for the liquids, with a means for maintaining a positive pressure on the liquids in the reservoir. A valved liquid supply line is connected to the reservoir for supplying the reservoir with the liquids to be mixed in the reservoir. The portion of the reservoir containing the liquids to be mixed is in communication with a pump which alternately causes a portion of the liquids to flow out of the pump and into the reservoir to mix the liquids. The fluids in the reservoir are in communication through a conduit with the pump which alternately causes a portion of the fluids to flow out of the pump and into the sphere. The conduit connecting the pump and sphere may contain a nozzle or other jet-forming structure such as a venturi for further mixing the fluids.

Booth, F. W.; Bruce, R. A. (inventors)

1973-01-01

262

Haar LBP Gabor Jet boosting Gabor Jet  

E-print Network

Boosting 1 boosting Haar LBP Gabor Jet boosting LBP Haar Gabor Jet boosting TP391. Further more, three kinds of local feature, Haar like feature, LBP histogram and Gabor jet are extracted, Haar like feature is more efficient for discriminating young and middle aged people, and Gabor Jet fits

Ai, Haizhou

263

Jet Shapes and Jet Algorithms in SCET  

E-print Network

Jet shapes are weighted sums over the four-momenta of the constituents of a jet and reveal details of its internal structure, potentially allowing discrimination of its partonic origin. In this work we make predictions for quark and gluon jet shape distributions in N-jet final states in e+e- collisions, defined with a cone or recombination algorithm, where we measure some jet shape observable on a subset of these jets. Using the framework of Soft-Collinear Effective Theory, we prove a factorization theorem for jet shape distributions and demonstrate the consistent renormalization-group running of the functions in the factorization theorem for any number of measured and unmeasured jets, any number of quark and gluon jets, and any angular size R of the jets, as long as R is much smaller than the angular separation between jets. We calculate the jet and soft functions for angularity jet shapes \\tau_a to one-loop order (O(alpha_s)) and resum a subset of the large logarithms of \\tau_a needed for next-to-leading logarithmic (NLL) accuracy for both cone and kT-type jets. We compare our predictions for the resummed \\tau_a distribution of a quark or a gluon jet produced in a 3-jet final state in e+e- annihilation to the output of a Monte Carlo event generator and find that the dependence on a and R is very similar.

Stephen D. Ellis; Andrew Hornig; Christopher Lee; Christopher K. Vermilion; Jonathan R. Walsh

2010-11-15

264

Turbulent Jets?  

NASA Astrophysics Data System (ADS)

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

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

2003-10-01

265

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

266

Electrohydrodynamic (EHD) stimulation of jet breakup  

NASA Technical Reports Server (NTRS)

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

Crowley, J. M.

1982-01-01

267

Breakup of diminutive Rayleigh jets  

NASA Astrophysics Data System (ADS)

Discharging a liquid from a nozzle at sufficient large velocity leads to a continuous jet that due to capillary forces breaks up into droplets. Here we investigate the formation of microdroplets from the breakup of micron-sized jets with ultra high-speed imaging. The diminutive size of the jet implies a fast breakup time scale ?c=??r3/? of the order of 100 ns, and requires imaging at 14×106 frames/s. We directly compare these experiments with a numerical lubrication approximation model that incorporates inertia, surface tension, and viscosity [J. Eggers and T. F. Dupont, J. Fluid Mech. 262, 205 (1994); X. D. Shi, M. P. Brenner, and S. R. Nagel, Science 265, 219 (1994)]. The lubrication model allows to efficiently explore the parameter space to investigate the effect of jet velocity and liquid viscosity on the formation of satellite droplets. In the phase diagram, we identify regions where the formation of satellite droplets is suppressed. We compare the shape of the droplet at pinch-off between the lubrication approximation model and a boundary-integral calculation, showing deviations at the final moment of the pinch-off. In spite of this discrepancy, the results on pinch-off times and droplet and satellite droplet velocity obtained from the lubrication approximation agree with the high-speed imaging results.

van Hoeve, Wim; Gekle, Stephan; Snoeijer, Jacco H.; Versluis, Michel; Brenner, Michael P.; Lohse, Detlef

2010-12-01

268

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

269

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

270

Marine Jet  

NASA Technical Reports Server (NTRS)

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

1978-01-01

271

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

272

Spatiotemporal instability of a confined capillary jet.  

PubMed

Recent experimental studies on the instability of capillary jets have revealed the suitability of a linear spatiotemporal instability analysis to ascertain the parametrical conditions for specific flow regimes such as steady jetting or dripping. In this work, an extensive analytical, numerical, and experimental description of confined capillary jets is provided, leading to an integrated picture both in terms of data and interpretation. We propose an extended, accurate analytic model in the low Reynolds number limit, and introduce a numerical scheme to predict the system response when the liquid inertia is not negligible. Theoretical predictions show remarkable accuracy when compared with the extensive experimental mapping. PMID:18999531

Herrada, M A; Gañán-Calvo, A M; Guillot, P

2008-10-01

273

Water jet rebounds on hydrophobic surfaces : a first step to jet micro-fluidics  

E-print Network

When a water jet impinges upon a solid surface it produces a so called hydraulic jump that everyone can observe in the sink of its kitchen. It is characterized by a thin liquid sheet bounded by a circular rise of the surface due to capillary and gravitational forces. In this phenomenon, the impact induces a geometrical transition, from the cylindrical one of the jet to the bi-dimensional one of the film. A true jet rebound on a solid surface, for which the cylindrical geometry is preserved, has never been yet observed. Here we experimentally demonstrate that a water jet can impact a solid surface without being destabilized. Depending on the incident angle of the impinging jet, its velocity and the degree of hydrophobicity of the substrate, the jet can i) bounce on the surface with a fixed reflected angle, ii) land on it and give rise to a supported jet or iii) be destabilized, emitting drops. Capillary forces are predominant at the sub-millimetric jet scale considered in this work, along with the hydrophobic nature of the substrate. The results presented in this letter raise the fundamental problem of knowing why such capillary hydraulic jump gives rise to this unexpected jet rebound phenomenon. This study furthermore offers new and promising possibilities to handle little quantity of water through "jet micro-fluidics"

Franck Celestini; R. Kofman; Xavier Noblin; Mathieu Pellegrin

2010-09-28

274

Coaxial atomizer liquid intact lengths  

NASA Technical Reports Server (NTRS)

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

Eroglu, Hasan; Chigier, Norman; Farago, Zoltan

1991-01-01

275

A new ejector refrigeration system with an additional jet pump  

Microsoft Academic Search

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

Jianlin Yu; Hua Chen; Yunfeng Ren; Yanzhong Li

2006-01-01

276

Jet energy scale determination in the D0 experiment  

NASA Astrophysics Data System (ADS)

The calibration of jet energy measured in the D0 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 ?+jet, Z+jet and dijet events, with jet transverse momentum pT>6 GeV and pseudorapidity range |?|<3.6. The corrections are measured separately for data and simulation, achieving a precision of 1.4-1.8% for jets in the central part of the calorimeter and up to 3.5% for the jets with pseudorapidity |?|=3.0. Specific corrections are extracted to enhance the description of jet 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.

Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Borysova, M.; Brandt, A.; Brandt, O.; Brock, R.; Bross, A.; Brown, D.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duperrin, A.; Dutt, S.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, V. N.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garbincius, P. H.; Garcia-Bellido, A.; García-González, J. A.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Golovanov, G.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Holzbauer, J. L.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jeong, M. S.; Jesik, R.; Jiang, P.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kajfasz, E.; Karmanov, D.; Katsanos, I.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kur?a, T.; Kuzmin, V. A.; Lammers, S.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magaña-Villalba, R.; Makovec, N.; Malik, S.; Malyshev, V. L.; Mansour, J.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Mulhearn, M.; Nagy, E.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nguyen, H. T.; Nunnemann, T.; Orduna, J.; Osman, N.; Osta, J.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M.-A.; Podstavkov, V. M.; Popov, A. V.; Prewitt, M.; Price, D.; Prokopenko, N.; Ochando, C.; Qian, J.; Quadt, A.; Quinn, B.; Raja, R.; Ratoff, P. N.; Razumov, I.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Sánchez-Hernández, A.; Sanders, M. P.; Santos, A. S.; Savage, G.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strauss, M.; Suter, L.; Svoisky, P.; Titov, M.; Tokmenin, V. V.; Tsai, Y.-T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Williams, M. R. J.; Wilson, G. W.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yang, S.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yin, H.; Yip, K.

2014-11-01

277

From Jet Counting to Jet Vetoes  

E-print Network

The properties of multi-jet events impact many LHC analysis. The exclusive number of jets at hadron colliders can be described in terms of two simple patterns: staircase scaling and Poisson scaling. In photon plus jets production we can interpolate between the two patterns using simple kinematic cuts. The associated theoretical errors are well under control. Understanding such exclusive jet multiplicities significantly impacts Higgs searches and searches for supersymmetry at the LHC.

Peter Schichtel; Christoph Englert; Erik Gerwick; Tilman Plehn; Steffen Schumann

2012-06-04

278

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

279

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.

280

Jet-like circulations occur in the `simple' geometries of gas planets and Earth's  

E-print Network

#12;Jet-like circulations occur in the `simple' geometries of gas planets and Earth's liquid The Jet Stream Conundrum Baldwin, Rhines, Huang & McIntyre, Nature 2007 #12;For Earth's oceans, density and jets Tracks of fast sea- surface drifters, Jakobsen 1994 #12;channels & atmospheres: PV stirring

281

Dielectric coating dynamics in electrified coaxial jets  

NASA Astrophysics Data System (ADS)

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

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

2006-11-01

282

Oscillatory system of the jet electromagnetic vibrator  

NASA Astrophysics Data System (ADS)

The article describes the system of nonlinear differential equations of the jet electromagnetic vibrator, designed to activate Newtonian and non-Newtonian fluids. The authors formulated the principles of designing electrical and hydro-mechanical components of the device based on the viscosity and density of the process liquid. The article describes experimental frequency characteristics of the system for liquids with the different rheological properties.

Bogdanov, E.; Rikkonen, S.; Nomokonova, Yu

2014-10-01

283

Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou  

E-print Network

Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou The paper presents an analytical model for the prediction of jet-by-jet diffraction. The source jet is modeled as a radiating cylinder on which one can sources that are becoming prominent in the simulation of jet noise. The scattering jet is modeled as an in

Papamoschou, Dimitri

284

Jet Reconstruction at RHIC  

E-print Network

Full jet reconstruction in heavy-ion collisions is expected to provide more sensitive measurements of jet quenching in hot QCD matter at RHIC. In this paper we review recent studies of jets utilizing modern jet reconstruction algorithms and their corresponding background subtraction techniques.

Sevil Salur; for the STAR Collaboration

2010-05-14

285

Jet Physics at CDF  

E-print Network

Recent results on jet physics at the Fermilab Tevatron $p\\bar p$ collider from the CDF Collaboration are presented. The main focus is put on results for the inclusive jet and dijet, $b\\bar b$ dijet, $W/Z+$jets and $W/Z+b$-jets production.

Kenichi Hatakeyama; for the CDF Collaboration

2007-12-12

286

Electrically Driven Jets  

Microsoft Academic Search

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

Geoffrey Taylor

1969-01-01

287

Supersonic gas jets  

NASA Astrophysics Data System (ADS)

The papers presented in this volume provide an overview of the current state of research in the gas dynamics of jet flows. In particular, attention is given to free supersonic jets and to the interaction of supersonic jets with one another and with obstacles under stationary and nonstationary flow conditions. Papers are presented on a method for calculating a weakly anisotropic supersonic turbulent jet in a subsonic slipstream; composite supersonic jets; the principal gas-dynamic characteristics of the processes occurring in gas-jet-driven shock-wave generators; and the construction of models for supersonic jet flows. For individual items see A84-16902 to A84-16918

Dulov, V. G.

288

CALCULATIONS FOR A MERCURY JET TARGET IN A SOLENOID MAGNET CAPTURE SYSTEM.  

SciTech Connect

A mercury jet is being considered as the production target for a muon storage ring facility to produce an intense neutrino beam. A 20 T solenoid magnet that captures pions for muon production surrounds the mercury target. As the liquid metal jet enters or exits the field eddy currents are induced. We calculate the effects that a liquid metal jet experiences in entering and exiting the magnetic field for the magnetic configuration considered in the Neutrino Factory Feasibility Study II.

GALLARDO, J.; KAHN, S.; PALMER, R.B.; THIEBERGER, P.; WEGGEL, R.J.; MCDONALD, K.

2001-06-18

289

The Giant Jet  

NASA Astrophysics Data System (ADS)

Thunderstorm clouds may discharge directly to the ionosphere in spectacular luminous jets - the longest electric discharges on our planet. The electric properties of jets, such as their polarity, conductivity, and currents, have been predicted by models, but are poorly characterized by measurements. Here we present an analysis of the first gigantic jet that with certainty has a positive polarity. The jet region in the mesosphere was illuminated by an unusual sprite discharge generated by a positive cloud-to-ground lightning flash shortly after the onset of the jet. The sprite appeared with elements in a ring at ~40 km distance around the jet, the elements pointing curving away from the jet. This suggests that the field close the jet partially cancels the field driving the sprite. From a simple model of the event we conclude that a substantial portion of the positive cloud potential must be carried to ~50 km altitude, which is also consistent with the observed channel expansion and the electromagnetic radiation associated with the jet. It is further shown that blue jets are likely to substantially modify the free electron content in the lower ionosphere because of increased electron attachment driven by the jet electric field. The model further makes clear the relationship between jets, gigantic jets, and sprites. This is the first time that sprites are used for sounding the properties of the mesosphere. The observations presented here will allow evaluation of theories for jet and gigantic jet generation and of their influence on the atmosphere-ionosphere system.

Neubert, T.; Chanrion, O.; Arnone, E.; Zanotti, F.; Cummer, S.; Li, J.; Füllekrug, M.; van der Velde, O.

2012-04-01

290

Project HyBuJET  

NASA Technical Reports Server (NTRS)

A conceptual Hypersonic Business Jet (HyBuJet) was examined. The main areas of concentration include: aerodynamics, propulsion, stability and control, mission profile, and atmospheric heating. In order to optimize for cruise conditions, a waverider configuration was chosen for the high lift drag ratio and low wave drag. The leading edge and lower surface of a waverider was mapped out from a known flow field and optimized for cruising at Mach 6 and at high altitudes. The shockwave generated by a waverider remains attached along the entire leading edge, allowing for a larger compression along the lower surface. Three turbofan ramjets were chosen as the propulsion of the aircraft due to the combination of good subsonic performance along with high speed propulsive capabilities. A combination of liquid silicon convective cooling for the leading edges with a highly radiative outer skin material was chosen to reduce the atmospheric heating to acceptable level.

Ramsay, Tom; Collet, Bill; Igar, Karyn; Kendall, Dewayne; Miklosovic, Dave; Reuss, Robyn; Ringer, Mark; Scheidt, Tony

1990-01-01

291

Jet fuels from synthetic crudes  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

292

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

293

Rapid leak detection with liquid crystals  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

294

High-speed jetting and spray formation from bubble collapse.  

PubMed

A method to create impacting jets at the micrometer length scale by means of a collapsing cavitation bubble is presented. A focused shock wave from a lithotripter leads to the nucleation of a cavitation bubble below a hole of 25 ?m diameter etched in a silicon plate. The plate is placed at an air-water interface. The expansion and collapse of the bubble leads to two separate jets--an initial slow jet of velocity ?10 m/s and a later faster jet of velocity ?50 m/s. The jets subsequently impact coaxially, resulting in a circular sheet of liquid in the plane perpendicular to their axis. The sheet is characterized by a ring of droplets at its rim and breaks up into a spray as the shock pressure is increased. The results demonstrate an approach to create a high-speed jet and fine spray on demand at the micrometer scale. PMID:22400617

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

2012-01-01

295

High-speed jetting and spray formation from bubble collapse  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

296

Dynamics of Liquid Nanojets Jens Eggers  

E-print Network

dynamics simulation of a jet of propane issuing from a nozzle 6 nm in diam was performed, which also payed of a liquid jet a few nanometers in diameter, based on a stochastic differential equation derived recently can be expected to be even larger than in confined geometries. Their importance is estimated

Eggers, Jens

297

High Pt Jet Physics  

E-print Network

In this contribution, a comprehensive review of the main aspects of high $\\pt$ jet physics in Run II at the Tevatron is presented. Recent measurements on inclusive jet production are discussed using different jet algorithms and covering a wide region of jet transverse momentum and jet rapidity. Several measurements, sensitive to a proper description of soft gluon radiation and the underlying event in hadron collisions, are shown. Finally, high $\\pt$ prompt photon measurements and studies on the production of electroweak bosons in association with jets in the final state are discussed.

M. Martinez

2006-10-13

298

Introduction to jets and jet finding Salvatore Aiola  

E-print Network

Introduction to jets and jet finding Salvatore Aiola Yale University July 3rd, 2014 #12;Outline factorization ¤ Jets as probes of the QGP ¤ Jet finding ¤ Experimental challenges of jets in HI ¤ Jets in ALICE) ¤ Anti-screening effect (opposite of QED!) ¤ Interaction strength grows with distance ¤ Confinement

299

Control of jet noise  

NASA Technical Reports Server (NTRS)

This reports describes experiments conducted at the High-Speed Jet Facility at the University of Southern California on supersonic jets. The goal of the study was to develop methods for controlling the noise emitted from supersonic jets by passive and/or active means. Work by Seiner et al (1991) indicates that eddy Mach wave radiation is the dominant noise source in a heated high speed jet. Eddy Mach radiation is caused by turbulent eddies traveling at supersonic speed in the shear layer of the jet. The convection velocity of the eddies decays with increasing distance from the nozzle exit due to the mixing of the jet stream with the ambient fluid. Once the convection speed reaches subsonic velocities, eddy Mach wave radiation ceases. To control noise, a rapid decay of the convection velocity is desired. This may be accomplished by enhanced mixing in the jet. In this study, small aspect ratio rectangular jet nozzles were tested. A flapping mode was noticed in the jets. By amplifying screech components of the jets and destabilizing the jet columns with a collar device, the flapping mode was excited. The result was a rapid decay of the jet velocity. A reduction in eddy Mach radiation in rectangular supersonic jets may be achieved with this device.

Schreck, Stefan

1993-01-01

300

A numerical model for coupling between atomization and spray dynamics in liquid rocket thrust chambers  

Microsoft Academic Search

This paper describes a novel method of coupling the atomization and spray combustion processes encountered in coaxial injection elements of liquid rocket engine thrust chambers. This method is based on the Jet-Embedding technique in which the liquid jet core equations and the gas phase equations are solved separately. The liquid and gas phase solutions, however, are coupled through the boundary

M. G. Giridharan; J. G. Lee; A. Krishnan; A. J. Przekwas; Klaus Gross

1992-01-01

301

Theory of Relativistic Jets  

NASA Astrophysics Data System (ADS)

Relativistic jets can be modeled as magnetohydrodynamic flows. We analyze the related equations and discuss the involved acceleration mechanisms, their relation to the collimation, to the jet confinement by its environment, and to possible rarefaction waves triggered by pressure imbalances.

Vlahakis, Nektarios

302

Radiation from relativistic jets  

Microsoft Academic Search

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the

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

2008-01-01

303

Jet physics in ALICE  

Microsoft Academic Search

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

Constantinos A. Loizides; Johann Wolfgang von Goethe

2005-01-01

304

Water jet rebounds on hydrophobic surfaces : a first step to jet micro-fluidics  

Microsoft Academic Search

When a water jet impinges upon a solid surface it produces a so called hydraulic jump that everyone can observe in the sink of its kitchen. It is characterized by a thin liquid sheet bounded by a circular rise of the surface due to capillary and gravitational forces. In this phenomenon, the impact induces a geometrical transition, from the cylindrical

Franck Celestini; R. Kofman; Xavier Noblin; Mathieu Pellegrin

2010-01-01

305

Multiple jet impingement flowfields  

NASA Technical Reports Server (NTRS)

Attention is given to the prediction of lift-system-induced aerodynamic effects in lift-jet VTOL aircraft, considering both analytical fluid-dynamics models and an empirical database. The methodology takes into account the effects of aircraft geometry and orientation as well as height above ground, lift-jet vector and splay directions, jet exit-flow conditions, and nozzle exit geometry.

Kotansky, D. R.

1986-01-01

306

Cosmic Radio Jets  

Microsoft Academic Search

Extragalactic radio sources, including quasars, are now typically understood as being produced by a pair of nearly symmetric, oppositely directed relativistic jets. While some these sources span megaparsecs, and are thus the largest physically connected structures in the universe, emitting regions identified as jets have now been found on all scales down to fractions of a parsec, and jets appear

Paul J. Wiita

2001-01-01

307

Jet Substructure Without Trees  

E-print Network

We present an alternative approach to identifying and characterizing jet substructure. An angular correlation function is introduced that can be used to extract angular and mass scales within a jet without reference to a clustering algorithm. This procedure gives rise to a number of useful jet observables. As an application, we construct a top quark tagging algorithm that is competitive with existing methods.

Martin Jankowiak; Andrew J. Larkoski

2011-06-30

308

Fluid jet electric discharge source  

SciTech Connect

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

Bender, Howard A. (Ripon, CA)

2006-04-25

309

Numerical study on the jet formation due to Rayleigh–Taylor instability  

NASA Astrophysics Data System (ADS)

The characteristic surface deformation quantities in the late-time stage of Rayleigh–Taylor (RT) instability were investigated numerically to link the present RT instability with the low-speed liquid jet theory, which was overlooked in previous studies. The velocity and width at the maximum-pressure location mirrored those associated with a vertical jet emanating downwards of an orifice injector under gravity. Thus, the results from laboratory low-speed jet emanation experiments were useful for predicting the disintegration behavior of a liquid jet formed by RT instability.

Li, Yikai; Umemura, Akira

2014-11-01

310

Jet substructure in ATLAS  

E-print Network

Measurements are presented of the jet invariant mass and substructure in proton-proton collisions at sqrt{s} = 7 TeV with the ATLAS detector using an integrated luminosity of 37 pb-1. These results exercise the tools for distinguishing the signatures of new boosted massive particles in the hadronic final state. Two "fat" jet algorithms are used, along with the filtering jet grooming technique that was pioneered in ATLAS. New jet substructure observables are compared for the first time to data at the LHC. Finally, a sample of candidate boosted top quark events collected in the 2010 data is analyzed in detail for the jet substructure properties of hadronic "top-jets" in the final state. These measurements demonstrate not only our excellent understanding of QCD in a new energy regime but open the path to using complex jet substructure observables in the search for new physics.

David W. Miller; for the ATLAS Collaboration

2011-10-05

311

Jet pump assisted arterial heat pipe  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

312

Cavitating vortex generation by a submerged jet  

SciTech Connect

The surface geometry of a cavitating vortex is determined in the limit of inviscid incompressible flow. The limit surface is an ovaloid of revolution with an axis ratio of 5: 3. It is shown that a cavitating vortex ring cannot develop if the cavitation number is lower than a certain critical value. Experiments conducted at various liquid pressures and several jet exit velocities confirm the existence of a critical cavitation number close to 3. At cavitation numbers higher than the critical one, the cavitating vortex ring does not develop. At substantially lower cavitation numbers (k {<=} 0.1), an elongated asymmetric cavitation bubble is generated, with an axial reentrant jet whose length can exceed the initial jet length by several times. This flow structure is called an asymmetric cavitating vortex, even though steady motion of this structure has not been observed.

Belyakov, G. V. [Russian Academy of Sciences, Institute for Dynamics of Geospheres (Russian Federation); Filippov, A. N. [Moscow State University of Food Production (Russian Federation)], E-mail: a.filippov@mgupp.ru

2006-05-15

313

Computer modeling of jet mixing in INEL waste tanks  

SciTech Connect

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

Meyer, P.A.

1994-01-01

314

Theory of laminar viscous jets  

NASA Astrophysics Data System (ADS)

Results of recent theoretical studies of laminar jet flows of a viscous incompressible fluid are reviewed. In particular, attention is given to plane, fan-shaped, axisymmetric, and swirling jet flows; jet flows behind bodies; and slipstream jet flows. The discussion also covers dissipation of mechanical energy in jet flows, jet flows with a zero excess momentum, and asymptotic series expansions in the theory of jet flows.

Martynenko, O. G.; Korovkin, V. N.; Sokovishin, Iu. A.

315

Refrigerated hydrogen gas jet for the Fermilab antiproton accumulator  

SciTech Connect

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

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

1995-07-01

316

Radiation Resistances of Dielectric Liquids  

NASA Technical Reports Server (NTRS)

Report presents data on effects of ionizing radiation on dielectric liquids for high-energy-density, pulsed-power capacitors. Based on Jet Propulsion Laboratory test results, search of NASA and Department of Energy computer files, survey of open literature, and contacts with manufacturers and suppliers. Covers 22 organic liquids, although detailed data found for only one compound, polydimethyl siloxane. Generic data on effects of radiation on compounds with similar chemical structures provided where data on specific compounds lacking.

Bouquet, Frank L.; Somoano, Robert B.

1987-01-01

317

Jet Substructure Without Trees  

SciTech Connect

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

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

2011-08-19

318

Interaction between jets during laser-induced forward transfer  

SciTech Connect

Simultaneous two-beam laser-induced forward transfer (LIFT) was carried out for various inter-beam separations, analyzing both the resulting printing outcomes and the corresponding liquid transfer dynamics. In a first experiment, droplets of an aqueous solution were printed onto a substrate at different inter-beam distances, which proved that a significant departure from the single-beam LIFT dynamics takes places at specific separations. In the second experiment, time-resolved imaging analysis revealed the existence of significant jet-jet interactions at those separations; such interactions proceed through a dynamics that results in remarkable jet deflection for which a possible onset mechanism is proposed.

Patrascioiu, A.; Florian, C.; Fernández-Pradas, J. M.; Morenza, J. L.; Serra, P., E-mail: pserra@ub.edu [Departament de Física Aplicada i Òptica, Universitat de Barcelona, Martí i Franquès 1, E-08028 Barcelona (Spain); Hennig, G. [DI Projekt AG, Flugplatz, CH-3368 Bleienbach (Switzerland); Delaporte, P. [Aix Marseille University, CNRS, LP3 UMR 7341, 163 Avenue de Luminy, 13288 Marseille (France)

2014-07-07

319

Interaction between jets during laser-induced forward transfer  

NASA Astrophysics Data System (ADS)

Simultaneous two-beam laser-induced forward transfer (LIFT) was carried out for various inter-beam separations, analyzing both the resulting printing outcomes and the corresponding liquid transfer dynamics. In a first experiment, droplets of an aqueous solution were printed onto a substrate at different inter-beam distances, which proved that a significant departure from the single-beam LIFT dynamics takes places at specific separations. In the second experiment, time-resolved imaging analysis revealed the existence of significant jet-jet interactions at those separations; such interactions proceed through a dynamics that results in remarkable jet deflection for which a possible onset mechanism is proposed.

Patrascioiu, A.; Florian, C.; Fernández-Pradas, J. M.; Morenza, J. L.; Hennig, G.; Delaporte, P.; Serra, P.

2014-07-01

320

Jet studies with STAR at RHIC: jet algorithms, jet shapes, jets in AA  

E-print Network

Hard scattered partons are predicted to be well calibrated probes of the hot and dense medium produced in heavy ion collisions. Interactions of these partons with the medium w ill result in modifications of internal jet structure in Au+Au events compared to that observed in the p+p/d+Au reference. Full jet reconstruction is a promising tool to measu re these effects without the significant biases present in measurements with high-$\\pT$ hadrons. One of the most significant challenges for jet reconstruction in the heavy ion environment comes from the correct characterization of the background fluctuations. The jet mome ntum irresolution due to background fluctuations has to be understood in order to recover the correct jet spectrum. Recent progress in jet reconstruction methodology is discu ssed, as well as recent measurements from p+p, d+Au and Au+Au collisions at $\\sqrt{s_\\mathrm{NN}}=200 \\gev$.

Jan Kapitan; for the STAR Collaboration

2011-11-08

321

What ignites optical jets?  

E-print Network

The properties of radio galaxies and quasars with and without optical or X-ray jets are compared. The majority of jets from which high-frequency emission has been detected so far (13 with optical emission, 11 with X-rays, 13 with both) are associated with the most powerful radio sources at any given redshift. It is found that optical/X-ray jet sources are more strongly beamed than the average population of extragalactic radio sources. This suggests that the detection or non-detection of optical emission from jets has so far been dominated by surface brightness selection effects, not by jet physics. It implies that optical jets are much more common than is currently appreciated.

S. Jester

2002-12-18

322

Cosmic Radio Jets  

Microsoft Academic Search

Extragalactic radio sources, including quasars, are now typically understood\\u000aas being produced by a pair of nearly symmetric, oppositely directed\\u000arelativistic jets. While some these sources span megaparsecs, and are thus the\\u000alargest physically connected structures in the universe, emitting regions\\u000aidentified as jets have now been found on all scales down to fractions of a\\u000aparsec, and jets appear

Paul J. Wiita

2001-01-01

323

Radiation from relativistic jets  

Microsoft Academic Search

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary mediu m show that particle acceleration occurs within the downstream jet. In the presence of relativistic j ets, instabilities such

K.-I. Nishikawa; Y. Mizunob; H. Sold; M. Medvedeve; B. Zhang; G. J. Fishmanh; R. Preecea

324

Baroclinic splitting of jets  

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

325

Jet physics in ALICE  

E-print Network

This work aims at the performance of the ALICE detector for the measurement of high-energy jets at mid-pseudo-rapidity in ultra-relativistic nucleus--nucleus collisions at LHC and their potential for the characterization of the partonic matter created in these collisions. In our approach, jets at high energy with E_{T}>50 GeV are reconstructed with a cone jet finder, as typically done for jet measurements in hadronic collisions. Within the ALICE framework we study its capabilities of measuring high-energy jets and quantify obtainable rates and the quality of reconstruction, both, in proton--proton and in lead--lead collisions at LHC conditions. In particular, we address whether modification of the jet fragmentation in the charged-particle sector can be detected within the high particle-multiplicity environment of the central lead--lead collisions. We comparatively treat these topics in view of an EMCAL proposed to complete the central ALICE tracking detectors. The main activities concerning the thesis are the following: a) Determination of the potential for exclusive jet measurements in ALICE. b) Determination of jet rates that can be acquired with the ALICE setup. c) Development of a parton-energy loss model. d) Simulation and study of the energy-loss effect on jet properties.

C. Loizides

2005-10-12

326

Supersonic air flow due to solid-liquid impact.  

PubMed

A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1 m/s, this air jet attains supersonic speeds already when the cavity is slightly larger than 1 mm in diameter. The structure of the air flow closely resembles that of compressible flow through a nozzle-with the key difference that here the "nozzle" is a liquid cavity shrinking rapidly in time. PMID:20366598

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

2010-01-15

327

Experimental study of underwater rock drilling using a pulsed Ho:YAG laser-induced jets  

Microsoft Academic Search

This paper is primarily an assessment of laser-induced water jets for boring rock surfaces. It also reports the result of\\u000a preliminary experiments of pulsed Ho:YAG laser-induced jets applied to drill a submerged rock specimen. The irradiation of\\u000a pulsed Ho:YAG laser beams at 3 Hz inside a thin metal tube produces intermittent water vapor bubbles which result in liquid\\u000a jet discharge from

K. Ohtani; D. Numata; K. Takayama; T. Kobayashi; K. Okatsu

2009-01-01

328

Shock Mitigation using Compressible Two-Phase Jets for Z-Pinch IFE Reactor Applications  

Microsoft Academic Search

Compressible liquid\\/gas jets offer the opportunity to limit and mitigate the mechanical consequences of rapid heating\\/evaporation of the protective jets in a high-yield, low repetition rate Inertial Fusion Energy (IFE) system such as the Z-Pinch IFE reactor. In this investigation, experiments have been conducted to quantify the extent by which a two-phase jet can attenuate a shock wave. The experiments

C. C. Lascar; D. L. Sadowski; S. I. Abdel-Khalik

2005-01-01

329

Flow field measurements in confined and submerged jet impingement  

SciTech Connect

The flow field of an axisymmetric, confined and submerged turbulent jet impinging normally on a flat plate was studied experimentally using laser-Doppler velocimetry. Single jets of a perfluorinated dielectric liquid (FC-77) were used in the experiments, with nozzle diameters of 3.18 and 6.35 mm, and nozzle-to-target plate spacings of up to 4 jet diameters. The experiments were conducted for turbulent jet Reynolds numbers in the range of 8,500 to 2,300. Velocity measurements just downstream of the nozzle exit show an increase in volume flow rate of 10--26% relative to the volume flow rate at the exit due to entrainment of the surrounding fluid. Very near the target plate, a maximum in the radial velocity is observed to occur at a radial distance from the stagnation point of 1 nozzle diameter. The location where transition to turbulence is observed in the wall jet is shown to move radially outward for increasing nozzle-to-target plate spacing, and lies between 2d and 2.5d for all cases. The flow field characteristics of the confined and submerged jets in the present study are contrasted to those reported in the literature for free-surface jets and submerged but unconfined jets.

Fitzgerald, J.A.; Garimella, S.V. [Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Mechanical Engineering

1996-12-31

330

Combustion Characteristics of Pressurized Swirling Spray Flame and Unsteady Two-Phase Exhaust Jet  

Microsoft Academic Search

The effects of flame enclosure and combustor pressure on the combustor flowfield and structure of turbulent spray flames have been investigated. The exhaust jet from the combustor was directed into water to simulate underwater propulsion applications. Two- phase interactions between the exhaust jet from the pressurized combustor and liquid water in an attached mixing chamber have been examined to address

Martin B. Linck; Ashwani K. Gupta; Guillaume Bourhis; Ken Yu

331

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

Microsoft Academic Search

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

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

2010-01-01

332

J_{E_T}: A Global Jet Finding Algorithm  

E-print Network

We introduce a new jet-finding algorithm for a hadron collider based on maximizing a J_{E_T} function for all possible combinations of particles in an event. This function prefers a larger value of the jet transverse energy and a smaller value of the jet mass. The jet shape is proved to be a circular cone in Cartesian coordinates with the geometric center shifted from the jet momentum toward the central region. The jet cone size shrinks for a more forward jet. We have implemented our J_{E_T} algorithm with a reasonable running time scaling as N n^3, where "N" is the total number of particles and "n" (much less than N) is the number of particles in a fiducial region. Many features of our J_{E_T} jets are similar to anti-k_t jets, including the reconstructed jet momentum and the "back-reaction" from soft contamination. Nevertheless, when the jet parameters in the two algorithms are matched using QCD jets, we find that the J_{E_T} algorithm has a larger efficiency than anti-k_t for identifying objects with hard splittings such as a W-jet.

Yang Bai; Zhenyu Han; Ran Lu

2014-11-13

333

The JET project  

Microsoft Academic Search

The Joint European Torus (JET) controlled thermonuclear Tokamak research facility is outlined. Basics of plasma confinement and Tokamak machine parameters are reviewed. The objectives of the JET program and international collaborative efforts in realizing it are discussed, along with some details on components (toroidal magnet, poloidal magnet system, vacuum chamber, mechanical support structures). Electrical power supply problems for the flywheel-alternator-rectifier

E. Bertolini

1976-01-01

334

Jet Tomography at RHIC  

E-print Network

The status of the use of hard probes in heavy ion collisions at RHIC is reviewed. The discovery of strong jet quenching at RHIC is a major success. However, in order to make full use of this new phenomenon for full jet emission tomography of the properties of the collision zone further development is needed, both experimentally and theoretically.

J. C. Dunlop

2007-07-10

335

Jet Lag in Athletes  

PubMed Central

Context: Prolonged transmeridian air travel can impart a physical and emotional burden on athletes in jet lag and travel fatigue. Jet lag may negatively affect the performance of athletes. Study Type: Descriptive review. Evidence Acquisition: A Medline search for articles relating to jet lag was performed (1990-present), as was a search relating to jet lag and athletes (1983-January, 2012). The results were reviewed for relevance. Eighty-nine sources were included in this descriptive review. Results: Behavioral strategies are recommended over pharmacological strategies when traveling with athletes; pharmacological aides may be used on an individual basis. Strategic sleeping, timed exposure to bright light, and the use of melatonin are encouraged. Conclusions: There is strong evidence that mood and cognition are adversely affected by jet lag. Some measures of individual and team performance are adversely affected as well. PMID:23016089

Lee, Aaron; Galvez, Juan Carlos

2012-01-01

336

Jet physics at CDF  

SciTech Connect

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

Melese, P.

1997-05-01

337

Description of Jet Breakup  

NASA Technical Reports Server (NTRS)

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

Papageorgiou, Demetrios T.

1996-01-01

338

Experimental and numerical investigations into the spontaneous triggering of jets in vapour explosions  

NASA Astrophysics Data System (ADS)

Investigations into the initial stages of vapour explosions, in particular the mechanisms which may initiate or ``trigger'' these events is reported. The central problems studied were the spontaneous triggering of liquid jets, and the underlying processes important to the behaviour of liquid jets failing onto and through other liquids before colliding with a solid surface. Experiments studying the behaviour of gravity driven liquid jets under isothermal and heat transfer conditions are reported. Detailed descriptions of the experimental design and apparatus, and an outline of the tests conducted to verify reliability of the equipment and repeatability of the experiments are given. It was shown in the isothermal jet experiments that air is entrained in quantities of similar volume to the jet when it impacts onto a pool of water. Entrained air affects gross jet behaviour in the pool such as penetration rate and radial spreading. Breakup of a dense jet liquid after collision with the pool base was influenced by the base material property. In the heat transfer jet experiments low melting point metals were released as jets into a pool of water. It was found that liquid water was entrained in the jet liquid, and could be extracted from the dried debris in measurable quantities after an experiment. The quantities of water measured and the nature of the recovered debris suggest that mixing of the molten metal and water may occur on a number of different length scales. Spontaneous triggers were observed in many experiments, and it was found that changing the base of the pool to a non-wetting surface had no discernible suppression effect on triggering. A numerical study was undertaken to investigate the benefits of using a free-surface algorithm to simulate liquid jet behaviour. The models developed using the Volume of Fluid technique gave very good comparisons with the isothermal jet experiments, but were not successful in simulating jets with heat transfer. A phenomenological model for triggering is presented based on the concepts of coolant constraint and melt coherence. Examples of triggering for different contact modes indicate that theoretical development of the model is warranted.

Storr, Greg John

339

J_{E_T}: A Global Jet Finding Algorithm  

E-print Network

We introduce a new jet-finding algorithm for a hadron collider based on maximizing a J_{E_T} function for all possible combinations of particles in an event. This function prefers a larger value of the jet transverse energy and a smaller value of the jet mass. The jet shape is proved to be a circular cone in Cartesian coordinates with the geometric center shifted from the jet momentum toward the central region. The jet cone size shrinks for a more forward jet. We have implemented our J_{E_T} algorithm with a reasonable running time scaling as N n^3, where "N" is the total number of particles and "n" (much less than N) is the number of particles in a fiducial region. Many features of our J_{E_T} jets are similar to anti-k_t jets, including the reconstructed jet momentum and the "back-reaction" from soft contamination. Nevertheless, when the jet parameters in the two algorithms are matched using QCD jets, we find that the J_{E_T} algorithm has a larger efficiency than anti-k_t for identifying objects with hard ...

Bai, Yang; Lu, Ran

2014-01-01

340

Optimized Parameters for a Mercury Jet Target  

SciTech Connect

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

Ding, X.; Kirk, H.

2010-12-01

341

Bubbling in unbounded coflowing liquids.  

PubMed

An investigation of the stability of low density and viscosity fluid jets and spouts in unbounded coflowing liquids is presented. A full parametrical analysis from low to high Weber and Reynolds numbers shows that the presence of any fluid of finite density and viscosity inside the hollow jet elicits a transition from an absolute to a convective instability at a finite value of the Weber number, for any value of the Reynolds number. Below that critical value of the Weber number, the absolute character of the instability leads to local breakup, and consequently to local bubbling. Experimental data support our model. PMID:16605912

Gañán-Calvo, Alfonso M; Herrada, Miguel A; Garstecki, Piotr

2006-03-31

342

Global stability of the focusing effect of fluid jet flows.  

PubMed

The global stability of the steady jetting mode of liquid jets focused by coaxial gas streams is analyzed both theoretically and experimentally. Numerical simulations allow one to identify the physical mechanisms responsible for instability in the low viscosity and very viscous regimes of the focused liquid. The characteristic flow rates for which global instability takes place are estimated by a simple scaling analysis. These flow rates do not depend on the pressure drop (energy) applied to the system to produce the microjet. Their dependencies on the liquid viscosity are opposite for the two extremes studied: the characteristic flow rate increases (decreases) with viscosity for very low (high) viscosity liquids. Experiments confirmed the validity of these conclusions. The minimum flow rates below which the liquid meniscus becomes unstable are practically independent of the applied pressure drop for sufficiently large values of this quantity. For all the liquids analyzed, there exists an optimum value of the capillary-to-orifice distance for which the minimum flow rate attains a limiting value. That limiting value represents the lowest flow rate attainable with a given experimental configuration in the steady jetting regime. A two-dimensional stability map with a high degree of validity is plotted on the plane defined by the Reynolds and capillary numbers based on the limiting flow rate. PMID:21517589

Montanero, J M; Rebollo-Muñoz, N; Herrada, M A; Gañán-Calvo, A M

2011-03-01

343

Jet impingement onto a cavity  

Microsoft Academic Search

Jet impingement onto surface finds wide application in industry. In laser processing an assisting gas jet is introduced either to shield the surface from oxidation reactions or initiating exothermic reaction to increase energy in the region irradiated by a laser beam. When an impinging gas jet is used for a shielding purpose, the gas jet enhances the convective cooling of

B. S. Yilbas; S. Z. Shuja; M. O. Budair

2002-01-01

344

Variable control of jet decay  

Microsoft Academic Search

The influence of blowing radially inward with a pair of control jets toward the centerline of and close to the exit from a circular main nozzle is investigated. Two regimes of control-jet influence exist, corresponding to conditions where the control jets are swept away in the turbulent mixing layer of the main jet or where they penetrate the central smooth-core

M. R. Davis

1982-01-01

345

A numerical model for coupling between atomization and spray dynamics in liquid rocket thrust chambers  

NASA Astrophysics Data System (ADS)

This paper describes a novel method of coupling the atomization and spray combustion processes encountered in coaxial injection elements of liquid rocket engine thrust chambers. This method is based on the Jet-Embedding technique in which the liquid jet core equations and the gas phase equations are solved separately. The liquid and gas phase solutions, however, are coupled through the boundary conditions at the interface between the phases. The computational grid for the gas phase calculations are adapted to the shape of the liquid jet core. The axial variation of droplet sizes are calculated using a stability analysis appropriate for the atomization regime of liquid jet breakup. The predictions of this method have been validated with experimental data on low speed water jets. Using this method, calculations are performed for the SSME fuel preburner single injector flow field. The results obtained are in good agreement with the predictions of the volume-of-fluid method.

Giridharan, M. G.; Lee, J. G.; Krishnan, A.; Przekwas, A. J.; Gross, Klaus

1992-07-01

346

Integrated coke, asphalt and jet fuel production process and apparatus  

DOEpatents

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

Shang, Jer Y. (McLean, VA)

1991-01-01

347

Large Eddy Simulation of jets laden with evaporating drops  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

348

The ways of mass transfer intensification in industrial jet scrubbers  

NASA Astrophysics Data System (ADS)

This paper is devoted to parametrical analysis of model, and is aimed at understanding its possibilities to find the most profitable conditions for the technical processes. These processes should consider the maximal extraction of gas and mechanical admixtures from the flow on the droplets of irrigating liquid and reduce the dimensions of hollow direct-flow jet scrubbers (DFJS) and Venturi scrubbers (VS).

Shilyaev, Michael; Khromova, Helen; Shirokova, Svetlana

2015-01-01

349

Influence of hole imperfection on jet cross flow interaction  

Microsoft Academic Search

The influence of a small hole geometry variation on the jet cross flow interaction is investigated experimentally using particle image velocimetry and liquid crystal thermography. The flow characteristics correspond to film cooling in gas turbines. A production imper- fection is represented with the small variation of the hole geometry. The experiments were conducted without and with the hole imper- fection

M. B. Jovanovic; H. C. de Lange; A. A. van Steenhoven

2006-01-01

350

Influence of hole imperfection on jet cross flow interaction  

Microsoft Academic Search

The influence of a small hole geometry variation on the jet cross flow interaction is investigated experimentally using particle image velocimetry and liquid crystal thermography. The flow characteristics correspond to film cooling in gas turbines. A production imperfection is represented with the small variation of the hole geometry. The experiments were conducted without and with the hole imperfection at three

M. B. Jovanovi?; H. C. de Lange; A. A. van Steenhoven

2006-01-01

351

Numerical simulation of turbulent jet primary breakup in Diesel engines  

E-print Network

Numerical simulation of turbulent jet primary breakup in Diesel engines Peng Zeng1 Marcus Herrmann and Aerospace Engineering Arizona State University "Micro-Macro Modelling and Simulation of Liquid-Vapour Flows" IRMA Strasbourg, 23.Jan.2008 #12;Introduction DNS of Primary Breakup in Diesel Injection Phase

Helluy, Philippe

352

Critical condition for the transformation from Taylor cone to cone-jet  

NASA Astrophysics Data System (ADS)

An energy method is proposed to investigate the critical transformation condition from a Taylor cone to a cone-jet. Based on the kinetic theorem, the system power allocation and the electrohydrodynamics stability are discussed. The numerical results indicate that the energy of the liquid cone tip experiences a maximum value during the transformation. With the proposed jetting energy, we give the critical transformation condition under which the derivative of jetting energy with respect to the surface area is greater than or equal to the energy required to form a unit of new liquid surface.

Wei, Cheng; Gang, Tie-Qiang; Chen, Li-Jie; Zhao, Yang

2014-06-01

353

Counterflowing Jet Subsystem Design  

NASA Technical Reports Server (NTRS)

A counterflowing jet design (a spacecraft and trans-atmospheric subsystem) employs centrally located, supersonic cold gas jets on the face of the vehicle, ejecting into the oncoming free stream. Depending on the supersonic free-stream conditions and the ejected mass flow rate of the counterflowing jets, the bow shock of the vehicle is moved upstream, further away from the vehicle. This results in an increasing shock standoff distance of the bow shock with a progressively weaker shock. At a critical jet mass flow rate, the bow shock becomes so weak that it is transformed into a series of compression waves spread out in a much wider region, thus significantly modifying the flow that wets the outer surfaces, with an attendant reduction in wave and skin friction drag and aerothermal loads.

Farr, Rebecca; Daso, Endwell; Pritchett, Victor; Wang, Ten-See

2010-01-01

354

Dilution jet mixing program  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

355

Jet Production at CDF  

SciTech Connect

The Run 2 at Tevatron will define a new level of precision for QCD studies in hadron collisions. Both collider experiments, CDF and D0, expect to collect up to 15 fb{sup -1} of data in this new run period. The increase in instantaneous luminosity, center-of-mass energy (from 1.8 TeV to 2 TeV) and the improved acceptance of the detectors will allow stringent tests of the Standard Model (SM) predictions in extended regions of jet transverse energy, E{sub T}{sup jet}, and jet pseudorapidity, {eta}{sup jet}. In the following, a review of some of the most important QCD results from Run 1 is presented, together with first preliminary Run 2 measurements (based on the very first data collected by the experiment) and future prospects as the integrated luminosity increases.

M. Martinez

2003-01-15

356

Cryogenically assisted abrasive jet micromachining of polymers  

NASA Astrophysics Data System (ADS)

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

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

2008-11-01

357

Free compressible jet investigation  

NASA Astrophysics Data System (ADS)

The nozzle pressure ratio (NPR) effect on a supersonic turbulent jet was investigated. A dedicated convergent/divergent nozzle together with a flow feeding system was designed and manufactured. A nozzle Mach exit of M j = 1.5 was selected in order to obtain a convective Mach number of M c = 0.6. The flow was investigated for over-expanded, correctly expanded and under-expanded jet conditions. Mach number, total temperature and flow velocity measurements were carried out in order to characterise the jet behaviour. The inlet conditions of the jet flow were monitored in order to calculate the nozzle exit speed of sound and evaluate the mean Mach number distribution starting from the flow velocity data. A detailed analysis of the Mach results obtained by a static Pitot probe and by a particle image velocimetry measurement system was carried out. The mean flow velocity was investigated, and the axial Mach decay and the spreading rate were associated with the flow structures and with the compressibility effects. Aerodynamics of the different jet conditions was evaluated, and the shock cells structures were detected and discussed correlating the jet structure to the flow fluctuation and local turbulence. The longitudinal and radial distribution of the total temperature was investigated, and the temperature profiles were analysed and discussed. The total temperature behaviour was correlated to the turbulent phenomena and to the NPR jet conditions. Self-similarity condition was encountered and discussed for the over-expanded jet. Compressibility effects on the local turbulence, on the turbulent kinetic energy and on the Reynolds tensor were discussed.

De Gregorio, Fabrizio

2014-03-01

358

Cosmic Radio Jets  

E-print Network

Extragalactic radio sources, including quasars, are now typically understood as being produced by a pair of nearly symmetric, oppositely directed relativistic jets. While some these sources span megaparsecs, and are thus the largest physically connected structures in the universe, emitting regions identified as jets have now been found on all scales down to fractions of a parsec, and jets appear to be a common element of most (maybe all) types of active galactic nuclei (AGN). We first summarize key observations of different classes of cosmic radio jets, and describe how they may be connected. Theoretical models for the launching and propagation of extragalactic jets are briefly described. All of these models assume a magnetized plasma, which typically amounts to only a small fraction of the accreted gas, is ejected from the vicinity of a supermassive black hole. The extreme complexity of the relevant physics has demanded numerical simulations to examine non-linear effects on the stability of propagating jets, and some recent results from these efforts are summarized.

Paul J. Wiita

2001-03-01

359

Radiation from Relativistic Jets  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

360

With acknowledgement to many colleagues in the former JET Joint Undertaking and JET EFDA contributors  

E-print Network

E) Terminated by design Q = 0.2 ( ) (reactor type shot) Fusionpower(MW) JET (1997) JET (1997) JET! "#$ % & $ ! " ! #$% & ' With acknowledgement to many colleagues in the former JET Joint Undertaking and JET EFDA contributors #12;! "#$ % & $ ' ( ' % ) * + , ' + - + + # . + + / 01 ( ' + + . + + / 1

361

Electrokinetic Power Generation from Liquid Water Microjets  

SciTech Connect

Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We have recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. JPCC 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic energy to electrical power. Previous studies of electrokinetic power production have reported low efficiencies ({approx}3%), limited by back conduction of ions at the surface and in the bulk liquid. Liquid microjets eliminate energy dissipation due to back conduction and, measuring only at the jet target, yield conversion efficiencies exceeding 10%.

Duffin, Andrew M.; Saykally, Richard J.

2008-02-15

362

30 CFR 56.7801 - Jet drills.  

Code of Federal Regulations, 2013 CFR

...SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to pressurize the equipment...

2013-07-01

363

30 CFR 57.7801 - Jet drills.  

Code of Federal Regulations, 2012 CFR

...HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A system to pressurize the...

2012-07-01

364

30 CFR 57.7801 - Jet drills.  

Code of Federal Regulations, 2013 CFR

...HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A system to pressurize the...

2013-07-01

365

30 CFR 56.7801 - Jet drills.  

...SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to pressurize the equipment...

2014-07-01

366

30 CFR 56.7801 - Jet drills.  

Code of Federal Regulations, 2012 CFR

...SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to pressurize the equipment...

2012-07-01

367

30 CFR 57.7801 - Jet drills.  

...HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A system to pressurize the...

2014-07-01

368

30 CFR 57.7801 - Jet drills.  

Code of Federal Regulations, 2011 CFR

...HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A system to pressurize the...

2011-07-01

369

30 CFR 56.7801 - Jet drills.  

Code of Federal Regulations, 2011 CFR

...SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Drilling and Rotary Jet Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to pressurize the equipment...

2011-07-01

370

Multi-jets formation using laser forward transfer  

NASA Astrophysics Data System (ADS)

The dynamics of multi-jets formation in liquid films has been investigated using the laser-induced forward transfer (LIFT) technique. This technique allows the deposition of micrometer-sized droplets with a high spatial resolution from a donor substrate to a receiver substrate. The donor was a silver nanoparticles ink-coated substrate. The interaction of the laser pulse with the donor ink layer generates an expanding bubble in the liquid which propels a jet towards the receiver. Silver lines have already been printed by depositing overlapping droplets in a “low speed” process. In order to increase the throughput, it is necessary to decrease the time between the depositions of two droplets. By scanning the beam of a high repetition rate UV picosecond laser (343 nm; 30 ps; 500 kHz) with a galvanometric mirror, successive pulses are focused on the silver nanoparticles ink-coated donor substrate. The shape and dynamics of single jets and adjacent jets have been investigated by means of a time-resolved imaging technique. By varying the distance between the laser spots, different behaviours were observed and compared to the printed droplets. A spacing of 25 ?m between laser spots was found to generate both stable jets and well-controlled, reproducible droplets at high speed.

Biver, Emeric; Rapp, Ludovic; Alloncle, Anne-Patricia; Delaporte, Philippe

2014-05-01

371

B-jets and z + b-jets at CDF  

SciTech Connect

The authors present CDF cross-section measurements for the inclusive production of b jets and the production of b jets in association with a Z{sup 0} boson. Both measurements are in reasonable agreement with NLO QCD predictions.

Jeans, Daniel; /Rome U.

2006-06-01

372

Explosive boiling of liquid nitrogen  

NASA Astrophysics Data System (ADS)

The present paper deals with experimental investigation of processes that occur when injecting a cryogenic fluid into water. The optical recording of the process of injection of a jet of liquid nitrogen into water has revealed the structure and the stages of this process. The results obtained can be used when studying a new method for producing gas hydrates based on the shock-wave method.

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

2014-12-01

373

Jet propulsion without inertia  

NASA Astrophysics Data System (ADS)

A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e., jetting) surfaces are considered and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number, which corresponds to the potential flow created by a source dipole at the sphere center. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria.

Spagnolie, Saverio E.; Lauga, Eric

2010-08-01

374

Jet propulsion without inertia  

E-print Network

A body immersed in a highly viscous fluid can locomote by drawing in and expelling fluid through pores at its surface. We consider this mechanism of jet propulsion without inertia in the case of spheroidal bodies, and derive both the swimming velocity and the hydrodynamic efficiency. Elementary examples are presented, and exact axisymmetric solutions for spherical, prolate spheroidal, and oblate spheroidal body shapes are provided. In each case, entirely and partially porous (i.e. jetting) surfaces are considered, and the optimal jetting flow profiles at the surface for maximizing the hydrodynamic efficiency are determined computationally. The maximal efficiency which may be achieved by a sphere using such jet propulsion is 12.5%, a significant improvement upon traditional flagella-based means of locomotion at zero Reynolds number. Unlike other swimming mechanisms which rely on the presentation of a small cross section in the direction of motion, the efficiency of a jetting body at low Reynolds number increases as the body becomes more oblate, and limits to approximately 162% in the case of a flat plate swimming along its axis of symmetry. Our results are discussed in the light of slime extrusion mechanisms occurring in many cyanobacteria.

Saverio E. Spagnolie; Eric Lauga

2010-05-04

375

The Twin Jet Nebula  

NASA Technical Reports Server (NTRS)

M2-9 is a striking example of a 'butterfly' or a bipolar planetary nebula. Another more revealing name might be the 'Twin Jet Nebula.' If the nebula is sliced across the star, each side of it appears much like a pair of exhausts from jet engines. Indeed, because of the nebula's shape and the measured velocity of the gas, in excess of 200 miles per second, astronomers believe that the description as a super-super-sonic jet exhaust is quite apt. This is much the same process that takes place in a jet engine: The burning and expanding gases are deflected by the engine walls through a nozzle to form long, collimated jets of hot air at high speeds. M2-9 is 2,100 light-years away in the constellation Ophiucus. The observation was taken Aug. 2, 1997 by the Hubble telescope's Wide Field and Planetary Camera 2. In this image, neutral oxygen is shown in red, once-ionized nitrogen in green, and twice-ionized oxygen in blue.

1997-01-01

376

Gudrun's (NLO) list pp->WW jet  

E-print Network

Gudrun's (NLO) list 2->3 pp->WW jet pp->VVV pp->H + 2 jets 2->4 pp->4 jets pp->tT + 2jets p->tT bB pp->V+ 3 jets pp->VV + 2 jets pp->VVV + jet pp->WW bB From technology point-of-view start with massless cases such as + 2 jets then add progressively more difficult calculations (additional scales

Huston, Joey

377

Effect of nozzle geometry and semi-confinement on the potential core of a turbulent axisymmetric free jet  

Microsoft Academic Search

The effects of nozzle geometry and confinement on the potential core and subsequent axial development of a turbulent axisymmetric air jet at a Reynolds number of 22 500 have been studied. Four jet exit conditions, namely, flat and fully developed velocity profiles for unconfined and semi-confined cases were investigated. Mean velocity and turbulence profiles were measured using laser-Doppler anemometry. Liquid

S. Ashforth-Frost; K. Jambunathan

1996-01-01

378

Numerical simulations of magnetized jets  

NASA Technical Reports Server (NTRS)

The present axisymmetric numerical simulations of light hypersonic jets allow unmagnetized jets and jets carrying a dynamically important magnetic field to be contrasted. After decelerating a weakly magnetized jet through a series of weak, oblique shocks, a Mach disk and a strong annular shock are encountered near the outer edges of the contact discontinuity separating the shocked fluid from the shocked ambient gas. Upon passing the annular shock, the gas quickly expands and enters a backflowing cocoon surrounding the jet. The overall speed of advance of the jet is reduced; matter near the jet axis which passes through the terminal Mach disk accumulates in a plug, and gas is discharged into the cocoon by the intermittent shedding of vortices. When magnetic stresses dominate, however, the jet is rapidly decelerated via a Mach disk and strong annular shock.

Lind, Kevin R.; Payne, David G.; Meier, David L.; Blandford, Roger D.

1989-01-01

379

Jet Substructure by Accident  

E-print Network

We propose a new search strategy for high-multiplicity hadronic final states. When new particles are produced at threshold, the distribution of their decay products is approximately isotropic. If there are many partons in the final state, it is likely that several will be clustered into the same large-radius jet. The resulting jet exhibits substructure, even though the parent states are not boosted. This "accidental" substructure is a powerful discriminant against background because it is more pronounced for high-multiplicity signals than for QCD multijets. We demonstrate how to take advantage of accidental substructure to reduce backgrounds without relying on the presence of missing energy. As an example, we present the expected limits for several R-parity violating gluino decay topologies. This approach allows for the determination of QCD backgrounds using data-driven methods, which is crucial for the feasibility of any search that targets signatures with many jets and suppressed missing energy.

Cohen, Timothy; Lisanti, Mariangela; Lou, Hou Keong

2012-01-01

380

Renewable jet fuel.  

PubMed

Novel strategies for sustainable replacement of finite fossil fuels are intensely pursued in fundamental research, applied science and industry. In the case of jet fuels used in gas-turbine engine aircrafts, the production and use of synthetic bio-derived kerosenes are advancing rapidly. Microbial biotechnology could potentially also be used to complement the renewable production of jet fuel, as demonstrated by the production of bioethanol and biodiesel for piston engine vehicles. Engineered microbial biosynthesis of medium chain length alkanes, which constitute the major fraction of petroleum-based jet fuels, was recently demonstrated. Although efficiencies currently are far from that needed for commercial application, this discovery has spurred research towards future production platforms using both fermentative and direct photobiological routes. PMID:24679258

Kallio, Pauli; Pásztor, András; Akhtar, M Kalim; Jones, Patrik R

2014-04-01

381

Photographic copy of photograph, aerial view looking down at Jet ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photographic copy of photograph, aerial view looking down at Jet Propulsion Laboratory, Edwards Test Station complex in 1961, with north toward the top of the view. Dd test station has been added to Test Stand 'D,' liquid nitrogen storage facility E-63 has been built, as well as several adjuncts to Test Stand 'C' behind earth barriers, such as oxidizer facility at 4263/E-64 and hydrogen tank at 4264/E-65. (JPL negative no. 384-3003-A, 12 December 1961) - Jet Propulsion Laboratory Edwards Facility, Edwards Air Force Base, Boron, Kern County, CA

382

Study on the wiping gas jet in continuous galvanizing line  

NASA Astrophysics Data System (ADS)

In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

Kweon, Yong-Hun; Kim, Heuy-Dong

2011-09-01

383

On magnetohydrodynamic solitons in jets  

NASA Technical Reports Server (NTRS)

Nonlinear solitary wave propagation in a compressible magnetic beam model of an extragalactic radio jet is examined and shown to lead to solitons of the Benjamin-Ono type. A number of similarities between such magnetic beam models of jets and models of solar photospheric flux tubes are pointed out and exploited. A single soliton has the appearance of a symmetric bulge on the jet which propagates faster than the jet's flow.

Roberts, B.

1987-01-01

384

Vertical slender jets  

NASA Technical Reports Server (NTRS)

The shape of a vertical slender jet of fluid falling steadily under the force of gravity is studied. The problem is formulated as a nonlinear free boundary-value problem for the potential. Surface tension effects are neglected. The use of perturbation expansions results in a system of equations that can be solved by an efficient numerical procedure. Computations were made for jets issuing from orifices in various shapes including an ellipse, a rectangle, and an equilateral triangle. Computational results are presented illustrating the propagation of discontinuities and the formation of thin sheets of fluid.

Geer, J. F.; Strikwerda, J. C.

1980-01-01

385

Studies of turbulent round jets through experimentation, simulation, and modeling  

NASA Astrophysics Data System (ADS)

This thesis studies the physics of the turbulent round jet. In particular, it focuses on three different problems that have the turbulent round jet as their base flow. The first part of this thesis examines a compressible turbulent round jet at its sonic condition. We investigate the shearing effect such a jet has when impinging on a solid surface that is perpendicular to the flow direction. We report on experiments to evaluate the jet's ability to remove different types of explosive particles from a glass surface. Theoretical analysis revealed trends and enabled modeling to improve the predictability of particle removal for various jet conditions. The second part of thesis aims at developing a non-intrusive measurement technique for free-shear turbulent flows in nature. Most turbulent jet investigations in the literature, both in the laboratory and in the field, required specialized intrusive instrumentation and/or complex optical setups. There are many situations in naturally-occurring flows where the environment may prove too hostile or remote for existing instrumentation. We have developed a methodology for analyzing video of the exterior of a naturally-occurring flow and calculating the flow velocity. We found that the presence of viscosity gradients affects the velocity analysis. While these effects produce consistent, predictable changes, we became interested in the mechanism by which the viscosity gradients affect the mixing and development of the turbulent round jet. We conducted a stability analysis of the axisymmetric jet when a viscosity gradient is present. Finally, the third problem addressed in this thesis is the growth of liquid droplets by condensation in a turbulent round jet. A vapor-saturated turbulent jet issues into a cold, dry environment. The resulting mixing produces highly inhomogeneous regions of supersaturation, where droplets grow and evaporate. Non-linear interactions between the droplet growth rate and the supersaturation field make analysis computationally taxing. A Probability Density Function (PDF) model for the concentration of scalars, as well as for the droplet number in different size bins, is developed. The growth of droplets as they evolve along the jet, for different downstream and radial positions, compared favorably with experimental measurements in the literature. We utilized a graphical processing unit with the PDF method to more efficiently compute the statistics of the droplet diameter in the non-uniform supersaturation field.

Keedy, Ryan

386

The JPL Direct Methanol Liquid-feed PEM Fuel Cell  

NASA Technical Reports Server (NTRS)

Recently, there has been a breakthrough in fuel cell technology in the Energy Storage Systems Group at the Jet Propulsion Laboratory with the develpment of a direct methanol, liquid-feed, solid polymer electrolyte membrane (PEM) fuel cell... The methanol liquid-feed, solid polymer electrolyte (PEM) design has numerous system level advantages over the gas-feed design. These include:...

Halpert, G.; Surampudi, S.

1994-01-01

387

Numerical simulation of jet noise  

Microsoft Academic Search

In the present work, computational aeroacoustics and parallel computers are used to conduct a study of flow-induced noise from different jet nozzle geometries. The nozzle is included as part of the computational domain. This is important to predict jet noise from nozzles associated with military aircraft engines. The Detached Eddy Simulation (DES) approach is used to simulate both the jet

Umesh Paliath

2006-01-01

388

Jets at Birth and Death  

NASA Astrophysics Data System (ADS)

The collimation of jets by magnetic fields is shown to need external pressure which, due to the stabilised pinch effect, may be considerably less than the magnetic pressure at the core of the jet, but must then operate over a much larger area. This article concentrates on the extreme situation where magnetism dominates within the jet.

Lynden-Bell, D.

389

Jet Noise Research at NASA  

NASA Technical Reports Server (NTRS)

A presentation outlining current jet noise work at NASA was given to the Naval Research Advisory Committee. Jet noise tasks in the Supersonics project of the Fundamental Aeronautics program were highlighted. The presentation gave an overview of developing jet noise reduction technologies and noise prediction capabilities. Advanced flow and noise diagnostic tools were also presented.

Henderson, Brenda S.; Huff,Dennis

2009-01-01

390

Jet Noise Research at NASA  

NASA Technical Reports Server (NTRS)

A presentation outlining current jet noise work at NASA was given at the NAVAIR Noise Workshop. Jet noise tasks in the Supersonics project of the Fundamental Aeronautics program were highlighted. The presentation gave an overview of developing jet noise reduction technologies and noise prediction capabilities. Advanced flow and noise diagnostic tools were also presented.

Henderson, Brenda

2008-01-01

391

Jet Propulsion Laboratory Introduction 1  

E-print Network

JPL Annual Report 1989 Jet Propulsion Laboratory #12;#12;CONTENTS Introduction 1 Director's Message for the period January 1 through December 31, 1989. JET PROPULSION LABORATORY California Institute of Technology Pasadena, California #12;INTRODUCTION TheJet Propulsion Laboratory QPL) of the California Institute

Waliser, Duane E.

392

Inclusive Jet & DijetInclusive Jet & Dijet Production at HERAProduction at HERA  

E-print Network

Inclusive Jet & DijetInclusive Jet & Dijet Production at HERAProduction at HERA M axime.8 2-jets p 2-jets DIS Inclusive jets DIS Proton PDF S 2-jets pPhoton PDF ObservablesQCD param. #12;M. Gouzevitch (Ecole Polytechnique, France) HEP2007, Manchester, 20/07/2007 3 Jet reconstruction · Iterative

393

Elucidating Jet Energy Loss Using Jets: Prospects from ATLAS  

E-print Network

Jets at the LHC are expected to provide the testing ground for studying QCD energy loss. In this contribution, we briefly outline the strategy that will be used to measure jets in ATLAS and how we will go about studying energy loss. We describe the utility of measuring the jet $R_{AA}$, the fragmentation function, and heavy flavor jets. Utilizing the collision energy provided by the LHC and the nearly hermetic and highly segmented calorimeter, ATLAS is expected to make important contributions to the understanding of parton energy loss using fully reconstructed jets.

N. Grau; for the ATLAS Collaboration

2009-10-20

394

Combined plasma/liquid cleaning of substrates  

DOEpatents

Apparatus and method for cleaning substrates. A substrate is held and rotated by a chuck and an atmospheric pressure plasma jet places a plasma onto predetermined areas of the substrate. Subsequently liquid rinse is sprayed onto the predetermined areas. In one embodiment, a nozzle sprays a gas onto the predetermined areas to assist in drying the predetermined areas when needed.

Selwyn, Gary S. (Los Alamos, NM); Henins, Ivars (Los Alamos, NM)

2003-04-15

395

Jet-Images: Computer Vision Inspired Techniques for Jet Tagging  

E-print Network

We introduce a novel approach to jet tagging and classification through the use of techniques inspired by computer vision. Drawing parallels to the problem of facial recognition in images, we define a jet-image using calorimeter towers as the elements of the image and establish jet-image preprocessing methods. For the jet-image processing step, we develop a discriminant for classifying the jet-images derived using Fisher discriminant analysis. The effectiveness of the technique is shown within the context of identifying boosted hadronic W boson decays with respect to a background of quark- and gluon- initiated jets. Using Monte Carlo simulation, we demonstrate that the performance of this technique introduces additional discriminating power over other substructure approaches, and gives significant insight into the internal structure of jets.

Josh Cogan; Michael Kagan; Emanuel Strauss; Ariel Schwarztman

2015-01-08

396

Jet-Images: Computer Vision Inspired Techniques for Jet Tagging  

E-print Network

We introduce a novel approach to jet tagging and classification through the use of techniques inspired by computer vision. Drawing parallels to the problem of facial recognition in images, we define a jet-image using calorimeter towers as the elements of the image and establish jet-image preprocessing methods. For the jet-image processing step, we develop a discriminant for classifying the jet-images derived using Fisher discriminant analysis. The effectiveness of the technique is shown within the context of identifying boosted hadronic W boson decays with respect to a background of quark- and gluon- initiated jets. Using Monte Carlo simulation, we demonstrate that the performance of this technique introduces additional discriminating power over other substructure approaches, and gives significant insight into the internal structure of jets.

Cogan, Josh; Strauss, Emanuel; Schwarztman, Ariel

2014-01-01

397

Spectroscopy with Supersonic Jets.  

ERIC Educational Resources Information Center

Discusses a new technique that enables spectroscopists to study gas phase molecules at temperatures below 1 K, without traditional cryogenic apparatus. This technique uses supersonic jets as samples for gas molecular spectroscopy. Highlighted are points in the theory of supersonic flow which are important for applications in molecular…

Skinner, Anne R.; Chandler, Dean W.

1980-01-01

398

Jet lag prevention  

MedlinePLUS

... zones. Jet lag occurs when your body's biological clock is not set with the time zone you ... Your body follows a 24-hour internal clock called a circadian rhythm. It tells your body when to go to sleep and when to wake up. Cues from your environment, such ...

399

Particle Acceleration in Jets  

NASA Technical Reports Server (NTRS)

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma ray burst (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments.

Nishikawa, Ken-Ichi

2005-01-01

400

Jet pumping oil wells  

Microsoft Academic Search

Programs for two different types of hand-held computers are presented to aid in the selection and sizing of downhole equipment. The calculation sequence used by the programs is described and user instructions for running them are included. Using the theory of jet pumping, which was discussed last month, as a basis, this article describes the procedures and specific equations used

M. L. Petrie; E. E. Smart; P. M. Wilson

1983-01-01

401

Beating jet lag  

PubMed Central

Jet lag is often cited as a cause of poor sporting performance. We report on the case of a rugby league player who flew 20 000 km and 12 time zones, then repeated the feat a few days later, prior to playing with distinction in an important final match in an international series. PMID:17261550

Milne, C J; Fuard, M H

2007-01-01

402

The physics of jets  

SciTech Connect

Recent data on the fragmentation of quarks and gluons is discussed in the context of phenomenological models of parton fragmentation. Emphasis is placed on the experimental evidence for parton showers as compared to a fixed order QCD treatment, on new data on inclusive hadron production and on detailed studies of baryon production in jets.

Hofmann, W.

1987-09-01

403

Instabilities of rotating jets  

E-print Network

When a jet of water is in free fall, it rapidly breaks up into drops, since a cylinder of water is unstable. This and other problems involving the form of a volume of water bound by surface tension have yielded a wealth ...

Zahniser, Russell, 1982-

2004-01-01

404

Jet Screech Noise Computation  

NASA Technical Reports Server (NTRS)

The near-field screech-tone noise of a typical underexpanded circular jet issuing from a sonic nozzle is simulated numerically. The self-sustained feedback loop is automatically established in the simulation. The computed shock-cell structure, acoustic wave length, screech tone frequencies, and sound pressure levels in the near field are in good agreement with existing experimental results.

Loh, Ching Y.; Hultgren, Lennart S.

2003-01-01

405

Jet Propulsion Laboratory Homepage  

NSDL National Science Digital Library

The Jet Propulsion Laboratory's (JPL) homepage provides links to spacecraft and mission information, imagery, news articles, events, features, and public services. Users can access articles and imagery from the Mars Rover and Cassini missions, images from the Spitzer Space Telescope, and an El Nino/La Nina Watch.

406

Analytical model of jet shielding  

NASA Technical Reports Server (NTRS)

An analytical model of the shielding of a stationary point noise source by a cylindrical jet is developed. The directivity function is derived which estimates the normalized sound pressure level at a far field receiver. The shielding model is compared to experimental data for a point noise source impinging on an unheated air jet and on a simulated hot air jet. The model compares favorably to measured shielding at receiver locations away from the jet axis. The trend of the estimated shielding diverges from the measured data as the jet axis is approached. Refinement of the model is discussed.

Gerhold, C. H.

1982-01-01

407

Rapidity-Dependent Jet Vetoes  

E-print Network

Jet vetoes are a prominent part of the signal selection in various analyses at the LHC. We discuss jet vetoes for which the transverse momentum of a jet is weighted by a smooth function of the jet rapidity. With a suitable choice of the rapidity-weighting function, such jet-veto variables can be factorized and resummed allowing for precise theory predictions. They thus provide a complementary way to divide phase space into exclusive jet bins. In particular, they provide a natural and theoretically clean way to implement a tight veto on central jets with the veto constraint getting looser for jets at increasingly forward rapidities. We mainly focus our discussion on the 0-jet case in color-singlet processes, using Higgs production through gluon fusion as a concrete example. For one of our jet-veto variables we compare the resummed theory prediction at NLL'+NLO with the recent differential cross section measurement by the ATLAS experiment in the $H\\to\\gamma\\gamma$ channel, finding good agreement. We also propose that these jet-veto variables can be measured and tested against theory predictions in other SM processes, such as Drell-Yan, diphoton, and weak diboson production.

Shireen Gangal; Maximilian Stahlhofen; Frank J. Tackmann

2014-12-15

408

Flow cytometer jet monitor system  

DOEpatents

A direct jet monitor illuminates the jet of a flow cytometer in a monitor wavelength band which is substantially separate from the substance wavelength band. When a laser is used to cause fluorescence of the substance, it may be appropriate to use an infrared source to illuminate the jet and thus optically monitor the conditions within the jet through a CCD camera or the like. This optical monitoring may be provided to some type of controller or feedback system which automatically changes either the horizontal location of the jet, the point at which droplet separation occurs, or some other condition within the jet in order to maintain optimum conditions. The direct jet monitor may be operated simultaneously with the substance property sensing and analysis system so that continuous monitoring may be achieved without interfering with the substance data gathering and may be configured so as to allow the front of the analysis or free fall area to be unobstructed during processing.

Van den Engh, Ger (Seattle, WA)

1997-01-01

409

Fragmentation in Jets at NNLO  

E-print Network

Beam and jet functions in Soft-Collinear Effective Theory describe collinear initial- and final-state radiation (jets), and enter in factorization theorems for N-jet production, the Higgs pT spectrum, etc. We show that they may directly be calculated as phase-space integrals of QCD splitting functions. At NLO all computations are trivial, as we demonstrate explicitly for the beam function, the transverse-momentum-dependent beam function, the jet function and the fragmenting jet function. This approach also highlights the role of crossing symmetry in these calculations. At NNLO we reproduce the quark jet function and calculate the fragmenting quark jet function for the first time. Here we use two methods: a direct phase-space integration and a reduction to master integrals which are computed using differential equations.

Mathias Ritzmann; Wouter J. Waalewijn

2014-07-11

410

Real vs. simulated relativistic jets  

E-print Network

Intensive VLBI monitoring programs of jets in AGN are showing the existence of intricate emission patterns, such as upstream motions or slow moving and quasi-stationary componentes trailing superluminal features. Relativistic hydrodynamic and emission simulations of jets are in very good agreement with these observations, proving as a powerful tool for the understanding of the physical processes taking place in the jets of AGN, microquasars and GRBs. These simulations show that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or ambient medium. Both observations and simulations suggest that shock-in-jet models may be an overly simplistic idealization when interpreting the emission structure observed in actual jets.

J. L. Gomez; J. M. Marti; I. Agudo; A. P. Marscher; S. G. Jorstad; M. A. Aloy

2005-01-03

411

A numerical model for atomization-spray coupling in liquid rocket thrust chambers  

NASA Technical Reports Server (NTRS)

The physical process of atomization is an important consideration in the stable operation of liquid rocket engines. Many spray combustion computational fluid dynamics (CFD) codes do not include an atomization sub-model but assume arbitrary drop size distributions, drop initial locations, and velocities. A method of coupling an atomization model with the spray model in a REFLEQS CFD code is presented. This method is based on a jet-embedding technique in which the equations governing the liquid jet core are solved separately using the surrounding gas phase conditions. The droplet initial conditions are calculated using a stability analysis appropriate for the atomization regime of liquid jet break-up.

Giridharan, M. G.; Krishnan, Anantha; Lee, J. J.; Przekwas, A. J.; Gross, K.

1992-01-01

412

Structure, alteration, and geochemistry of the Charlotte quartz vein stockwork, Mt Charlotte gold mine, Kalgoorlie, Australia: time constraints, down-plunge zonation, and fluid source  

NASA Astrophysics Data System (ADS)

The Kalgoorlie district in the Archean Yilgarn Craton, Western Australia, comprises two world-class gold deposits: Mt Charlotte (144 t Au produced to 2013) in the northwest and the Golden Mile (1,670 t Au) in the southeast. Both occur in a folded greenschist-facies gabbro sill adjacent to the Golden Mile Fault (D2) in propylitic alteration associated with porphyry dikes. At Mt Charlotte, a shear array of fault-fill veins within the Golden Mile Fault indicates sinistral strike-slip during Golden Mile-type pyrite-telluride mineralization. The pipe-shaped Charlotte quartz vein stockwork, mined in bulk more than 1 km down plunge, is separated in time by barren D3 thrusts from Golden Mile mineralization and alteration, and occurs between two dextral strike-slip faults (D4). Movement on these faults generated an organized network of extension and shear fractures opened during the subsequent infiltration of high-pressure H2S-rich fluid at 2,655 ± 13 Ma (U-Pb xenotime). Gold was deposited during wall rock sulphidation in overlapping vein selvages zoned from deep albite-pyrrhotite (3 g/t Au) to upper muscovite-pyrite assemblages (5 g/t Au bulk grade). Chlorite and fluid inclusion thermometry indicate that this kilometre-scale zonation is due to fluid cooling from 410-440 °C at the base to 350-360 °C at the top of the orebody, while the greenstone terrane remained at 250 °C ambient temperature and at 300 MPa lithostatic pressure. The opened fractures filled with barren quartz and scheelite during the retrograde stage (300 °C) of the hydrothermal event. During fracture sealing, fluid flux was periodically restricted at the lower D3 thrust. Cycles of high and low up-flow, represented by juvenile H2O-CO2 and evolved H2O-CO2-CH4 fluid, respectively, are recorded by the REE and Sr isotope compositions of scheelite oscillatory zones. The temperature gradient measured in the vein stockwork points to a hot (>600 °C) fluid source 2-4 km below the mine workings, and several kilometres above the base of the greenstone belt. Mass balance calculations involving bulk ore indicate enrichment of both felsic (K, Rb, Cs, Li, Ba, W) and mafic elements (Ca, Sr, Mg, Ni, V, Cr, Te), a source signature compatible with the local high-Mg porphyry suite but not with the meta-gabbro host rock. The initial 87Sr/86Sr ratios of the vein scheelites (0.7014-0.7016) are higher than the mantle ratio of the meta-gabbro (0.7009-0.7011) and overlap those of high-Mg monzodiorite intrusions (0.7016-0.7018) emplaced along the Golden Mile Fault at 2,662 ± 6 Ma to 2,658 ± 3 Ma.

Mueller, Andreas G.

2014-06-01

413

Orifice and impingement flow fields in confined jet impingement  

SciTech Connect

The flow fields in the orifice and the confinement region of a normally impinging, axisymmetric, confined and submerged liquid jet were computationally investigated. Numerical predictions were made for orifice diameters of 3.18 and 6.35 mm at several orifice-to-target plate spacings, with turbulent jet Reynolds number ranging from 8,500 to 23,000. The commercial finite-volume code FLUENT was used to solve the flow fields using a modified {kappa}-{epsilon} model based on renormalization group theory. The predicted characteristics of the separation region at the entrance of the orifice agree with experiments in the literature. The pressure drop across the orifice was predicted to within 5% of proposed empirical correlations based on published experimental data. The computed flow patterns in the confinement region of the impinging jet were in good qualitative agreement with flow visualizations; however, a secondary recirculation zone observed in experiments was not predicted by the models.

Morris, G.K.; Garimella, S.V. [Univ. of Wisconsin, Milwaukee, WI (United States). Dept. of Mechanical Engineering

1996-12-31

414

A Comparison between Plasma Synthetic Jets and Conventional Jets  

NASA Astrophysics Data System (ADS)

The flow field of a jet created by an actuator employing a surface dielectric barrier discharge (DBD) is investigated experimentally via PIV measurements, and a comparison of its fluid dynamic characteristics with mechanically driven continuous and synthetic jets is presented. The plasma synthetic jet actuator consists of two electrodes arranged asymmetrically separated by a dielectric material and under an input of high voltage, high frequency AC at ambient conditions of pressure and temperature, a region of DBD plasma is formed starting from the edges of the exposed electrode. In an initially quiescent medium, this plasma region is observed to induce and sustain entrainment of near wall fluid, the volume of which is ejected out from the base of the actuator in the form of a jet. The electrodes are shaped either in the form of annular arrays for rendering a circular jet, or linear arrays for rendering a rectangular jet. Unsteady pulsing of the PSJA at time scales decoupled to the AC input frequency results in a flow field dominated by counter rotating vortical structures similar to conventional synthetic jets. The jet outputs are found to be affected by a variety of system inputs, including the input electrical power, pulsing frequency, and actuator dimension. The effects of varying the above parameters on the self similarity behavior of plasma synthetic jets are examined and compared to mechanically driven jets.

Santhanakrishnan, Arvind; Jacob, Jamey

2007-11-01

415

SIMULATION AND MOCKUP OF SNS JET-FLOW TARGET WITH WALL JET FOR CAVITATION DAMAGE MITIGATION  

SciTech Connect

Pressure waves created in liquid mercury pulsed spallation targets at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory induce cavitation damage on the stainless steel target container. The cavitation damage is thought to limit the lifetime of the target for power levels at and above 1 MW. Severe through-wall cavitation damage on an internal wall near the beam entrance window has been observed in spent-targets. Surprisingly though, there is very little damage on the walls that bound an annular mercury channel that wraps around the front and outside of the target. The mercury flow through this channel is characterized by smooth, attached streamlines. One theory to explain this lack of damage is that the uni-directional flow biases the direction of the collapsing cavitation bubble, reducing the impact pressure and subsequent damage. The theory has been reinforced by in-beam separate effects data. For this reason, a second-generation SNS mercury target has been designed with an internal wall jet configuration intended to protect the concave wall where damage has been observed. The wall jet mimics the annular flow channel streamlines, but since the jet is bounded on only one side, the momentum is gradually diffused by the bulk flow interactions as it progresses around the cicular path of the target nose. Numerical simulations of the flow through this jet-flow target have been completed, and a water loop has been assembled with a transparent test target in order to visualize and measure the flow field. This paper presents the wall jet simulation results, as well as early experimental data from the test loop.

Wendel, Mark W [ORNL; Geoghegan, Patrick J [ORNL; Felde, David K [ORNL

2014-01-01

416

Dilution Jets in Accelerated Cross Flows. Degree awarded May 1981  

NASA Technical Reports Server (NTRS)

Results of flow visualization experiments and measurements of the temperature field produced by a single jet and a row of dilution jets issued into a reverse flow combustor are presented. The flow in such combustors is typified by transverse and longitudinal acceleration during the passage through its bending section. The flow visualization experiments were designed to examine the separate effects of longitudinal and transverse acceleration on the jet trajectory and spreading rate. A model describing a dense single jet in a lighter accelerating cross flow is developed. The model is based on integral conservation equations, including the pressure terms appropriate to accelerating flows. It uses a modified entrainment correlation obtained from previous experiments of a jet in a cross stream. The flow visualization results are compared with the model calculations in terms of trajectories and spreading rates. Each experiment is typified by a set of three parameters: momentum ratio, density ratio, and the densimetric Froude number. When injection velocities are large or densities are small, the Froude number becomes very large and hence, unimportant. Therefore, the Froude number is generally significant in describing liquid experiments but is unimportant for the gas experiments in the combustor. Agreement between test and calculated results is encouraging but tends to become poorer with increasing momentum ratio. The temperature measurements are presented primarily in the form of consecutive normalized temperature profiles. Some interpolated isothermal contours are also shown. The single jet trajectories are consistently found to be swept towards the inner wall of the bend, whether injection is from the outer or the inner wall. This behavior is explained by a drifting effect which consists of a transverse velocity component across the combustor due to the developing nature of the flow along it. Plots of lateral temperature distributions of the jet indicate that under longitudinal acceleration conditions the thermal spreading of the jet may be completely suppressed. Comparison between combustor experimental results and model calculations shows poor agreement due to the drifting effect which is not taken into consideration in the model calculations. The row of jets experiments are characterized by two additional parameters: spacing ratio and confinement parameter. The results are shown in the form of consecutive normalized temperature profiles. The confinement parameter appears to become increasingly important with decreasing spacing ratio, in particular when its effect is enhanced by the drifting phenomenon and associated pressure field. A tightly spaced row of jets injected from the inner wall, prior to the bend, is surprisingly kept attached to the inner wall in spite of the strong turning. A similar attachment for a jet injected from the outer wall is not observed.

Lipshitz, Abraham; Greber, Isaac; Riddlebaugh, Stephen M. (Technical Monitor)

1984-01-01

417

BIPOLAR JETS LAUNCHED FROM ACCRETION DISKS. II. THE FORMATION OF ASYMMETRIC JETS AND COUNTER JETS  

SciTech Connect

We investigate the jet launching from accretion disks, in particular the formation of intrinsically asymmetric jet/counter jet systems. We perform axisymmetric MHD simulations of the disk-jet structure on a bipolar computational domain covering both hemispheres. We apply various models such as asymmetric disks with (initially) different scale heights in each hemisphere, symmetric disks into which a local disturbance is injected, and jets launched into an asymmetric disk corona. We consider both a standard global magnetic diffusivity distribution and a novel local diffusivity model. Typical disk evolution first shows substantial disk warping and then results in asymmetric outflows with a 10%-30% mass flux difference. We find that the magnetic diffusivity profile is essential for establishing a long-term outflow asymmetry. We conclude that bipolar asymmetry in protostellar and extragalactic jets can indeed be generated intrinsically and maintained over a long time by disk asymmetries and the standard jet launching mechanism.

Fendt, Christian [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Sheikhnezami, Somayeh, E-mail: fendt@mpia.de, E-mail: nezami@mpia.de [Present address: Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad (Iran, Islamic Republic of)

2013-09-01

418

Liquid transport due to light scattering.  

PubMed

Using experiments and theory, we show that light scattering by inhomogeneities in the index of refraction of a fluid can drive a large-scale flow. The experiment uses a near-critical, phase-separated liquid, which experiences large fluctuations in its index of refraction. A laser beam traversing the liquid produces a interface deformation on the scale of the experimental setup and can cause a liquid jet to form. We demonstrate that the deformation is produced by a scattering-induced flow by obtaining good agreements between the measured deformations and those calculated assuming this mechanism. PMID:17501199

Schroll, Robert D; Wunenburger, Régis; Casner, Alexis; Zhang, Wendy W; Delville, Jean-Pierre

2007-03-30

419

Jet breakup and droplet formation in near-critical regime of carbon dioxide–dichloromethane system  

Microsoft Academic Search

The jet breakup and droplet formation mechanism of a liquid in the near-critical conditions of a solvent–antisolvent system is examined with high-speed visualization experiments and simulated using a front tracking\\/finite volume method. The size of droplets formed under varying system pressure at various jet breakup regimes is measured with a Global Sizing Velocimetry, using the shadow sizing method. A stainless

Lai Yeng Lee; Liang Kuang Lim; Jinsong Hua; Chi-Hwa Wang

2008-01-01

420

Computational modeling of jet induced mixing of cryogenic propellants in low-G  

NASA Technical Reports Server (NTRS)

The SOLA-ECLIPSE Code is being developed to enable computational prediction of jet induced mixing in cryogenic propellant tanks in a low-gravity environment. Velocity fields, predicted for scale model tanks, are presented which compare favorably with the available experimental data. A full scale liquid hydrogen tank for a typical Orbit Transfer Vehicle is analyzed with the conclusion that coupling an axial mixing jet with a thermodynamic vent system appears to be a viable concept for the control of tank pressure.

Hochstein, J. I.; Gerhart, P. M.; Aydelot, J. C.

1984-01-01

421

Quantitative Interferometry in the Severe Acoustic Environment of Resonant Supersonic Jets  

NASA Technical Reports Server (NTRS)

There is renewed interest in the study of supersonic jets due to advances in high speed jet propulsion, supersonic combustion, and jet noise suppression for the next generation supersonic commercial transport. Understanding fundamental fluid dynamic and acoustic processes for these applications requires quantitative velocity, density and temperature measurements. In this paper we present data demonstrating a new, robust interferometer that can provide accurate data even in the presence of intense acoustic fields. This novel interferometer, the Liquid Crystal Point Diffraction Interferometer (LCPDI), was developed earlier for space flight experiments and is applied here to the case of a supersonic shock-containing jet. The LCPDI is briefly described, then integrated line-of-sight density data from the LCPDI for two underexpanded free jets are presented. The experimental shock spacings agree well with theory.

Mercer, Carolyn R.; Raman, Ganesh

1998-01-01

422

Phenomenology of photon-jets  

NASA Astrophysics Data System (ADS)

One of the challenges of collider physics is to unambiguously associate detector-based objects with the corresponding elementary physics objects. A particular example is the association of calorimeter-based objects such as “jets,” identified with a standard (IR-safe) jet algorithm, with the underlying physics objects, which may be QCD-jets (arising from a scattered parton), electrons, photons or, as discussed here, photon-jets (a group of collinear photons). This separation is especially interesting in the context of Higgs search, where the signal includes events with two photons (in the Standard Model) as well as events with two photon-jets (in a variety of Beyond the Standard Model scenarios), while QCD provides ever-present background. Here we describe the implementation of techniques from the rapidly evolving area of jet substructure studies, not only to enhance the more familiar photon-QCD separation, but also to separately distinguish photon-jets, i.e., to separate usual jets into three categories: single photons, photon-jets and QCD-jets. The efficacy of these techniques for separation is illustrated through studies of simulated data.

Ellis, Stephen D.; Roy, Tuhin S.; Scholtz, Jakub

2013-01-01

423

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube. 8 figs.

Kong, P.C.; Watkins, A.D.

1999-05-25

424

Liquid injection plasma deposition method and apparatus  

DOEpatents

A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube.

Kong, Peter C. (Idaho Falls, ID); Watkins, Arthur D. (Idaho Falls, ID)

1999-01-01

425

Instability of low viscosity elliptic jets with varying aspect ratio  

NASA Astrophysics Data System (ADS)

In this work an analytical description of capillary instability of liquid elliptic jets with varying aspect ratio is presented. Linear stability analysis in the long wave approximation with negligible gravitational effects is employed. Elliptic cylindrical coordinate system is used and perturbation velocity potential substituted in the Laplace equation to yield Mathieu and Modified Mathieu differential equations. The dispersion relation for elliptical orifices of any aspect ratio is derived and validated for axisymmetric disturbances with m = 0, in the limit of aspect ratio, ?= 1, i.e. the case of a circular jet. As Mathieu functions and Modified Mathieu function solutions converge to Bessel's functions in this limit the Rayleigh-Plateau instability criterion is met. Also, stability of solutions corresponding to asymmetric disturbances for the kink mode, m = 1 and flute modes corresponding to m >=2 is discussed. Experimental data from earlier works is used to compare observations made for elliptical orifices with ?1. This novel approach aims at generalizing the results pertaining to cylindrical jets with circular cross section leading to better understanding of breakup in liquid jets of various geometries.

Kulkarni, Varun

2011-11-01

426

Behavior of Water Jet Accompanied with Air Suction  

NASA Astrophysics Data System (ADS)

In order to atomize a liquid, the authors have investigated the behavior of air-water jets. In a series of experiments, we have discovered a strange phenomenon that the water jet accompanied with air suction from the free surface has made a periodic radial splash of water drop. The purpose of the present paper is to clear out the origin of this phenomenon and the behavior of water jet accompanied with air suction. The behavior of water jet has been photographed by a digital camera aided with a flashlight and high-speed video camera. Those experiments enable us to find the origin of a periodic radial splash due to a formation of single air bubble at the flow separation region inside the nozzle and due to explosive expansion of the bubble after injected in the free space. In order to analyze the radial splash of water, we have conducted the equation of spherical liquid membrane. The numerical results obtained have been compared with the experimental results and good agreement has been obtained in radial expansion velocity.

Kawakami, Hironobu; Ishido, Tsutomu; Ihara, Akio

427

Jet decorrelation and jet shapes at the Tevatron  

SciTech Connect

We present results on measurements of jet shapes and jet azimuthal decorrelation from {bar p}P collisions at {radical}s = 1.8 TeV using data collected during the 1992-1993 run of the Fermilab Tevatron. Jets are seen to narrow both with increasing Awe {sub TTY} and increasing rapidity. While HERWIG, a puritan shower Monte Carlo, predicts slightly narrower jets, it describes the trend of the data well; NO CD described qualitative features of the data but is sensitive to both renormalization scale and jet definitions. Jet azimuthal decorrelation has been measured out to five units of pseudorapidity. While next-to-leading order CD and a leading-log approximation based on BFKL resummation fail to reproduce the effect, HERWIG describes the data well.

Heuring, T.C. [Florida State Univ., Tallahassee, FL (United States)

1996-07-01

428

Jet hadrochemistry as a characteristics of jet quenching  

E-print Network

Jets produced in nucleus-nucleus collisions at the LHC are expected to be strongly modified due to the interaction of the parton shower with the dense QCD matter. Here, we point out that jet quenching can leave signatures not only in the longitudinal and transverse jet energy and multiplicity distributions, but also in the hadrochemical composition of the jet fragments. In particular, we show that even in the absence of medium effects at or after hadronization, the medium-modification of the parton shower can result in significant changes in jet hadrochemistry. We discuss how jet hadrochemistry can be studied within the high-multiplicity environment of nucleus-nucleus collisions at the LHC.

Sebastian Sapeta; Urs Achim Wiedemann

2007-07-24

429

Particle-level pileup subtraction for jets and jet shapes  

E-print Network

We present an extension to the jet area-based pileup subtraction for both jet kinematics and jet shapes. A particle-level approach is explored whereby the jet constituents are corrected or removed using an extension of the methods currently being employed by the LHC experiments. Several jet shapes and nominal jet radii are used to assess the performance in simulated events with pileup levels equivalent to approximately 30 and 100 interactions per bunch crossing, which are characteristic of both the LHC Run I and Run II conditions. An improved performance in removing the pileup contributions is found when using the new subtraction method. The performance of the new procedure is also compared to other existing methods.

Peter Berta; Martin Spousta; David W. Miller; Rupert Leitner

2014-03-12

430

High air volume to low liquid volume aerosol collector  

DOEpatents

A high air volume to low liquid volume aerosol collector. A high volume flow of aerosol particles is drawn into an annular, centripetal slot in a collector which directs the aerosol flow into a small volume of liquid pool contained is a lower center section of the collector. The annular jet of air impinges into the liquid, imbedding initially airborne particles in the liquid. The liquid in the pool continuously circulates in the lower section of the collector by moving to the center line, then upwardly, and through assistance by a rotating deflector plate passes back into the liquid at the outer area adjacent the impinging air jet which passes upwardly through the liquid pool and through a hollow center of the collector, and is discharged via a side outlet opening. Any liquid droplets escaping with the effluent air are captured by a rotating mist eliminator and moved back toward the liquid pool. The collector includes a sensor assembly for determining, controlling, and maintaining the level of the liquid pool, and includes a lower centrally located valve assembly connected to a liquid reservoir and to an analyzer for analyzing the particles which are impinged into the liquid pool.

Masquelier, Donald A. (Tracy, CA); Milanovich, Fred P. (Lafayette, CA); Willeke, Klaus (Cincinnati, OH)

2003-01-01

431

Current jet fuel trends  

NASA Technical Reports Server (NTRS)

Data concerning the properties of commercial jet fuels during the period between 1974 and 1979 are discussed. During this period the average aromatics content of fuels increased from 16% to 17.5%. It is evident that the arrival of Alaska North Slope crude in 1977 had a significant impact upon the aromatics content of jet fuel supply at West Coast points with less effect upon the entire United States domestic market. This increase in aromatics has not been accompanied by a corresponding reduction in burning quality as measured by smoke point. There has been a reduction of .6 smoke point on the average. Looking at hydrogen content as a measure of burning quality, the all refinery average calculated hydrogen for 1978 was approximately 13.7%. The relationship between hydrogen content and aromatics content shows a slope of .043% reduction in hydrogen for 1% increase in aromatics.

Campbell, P. P.

1980-01-01

432

Double-focusing mixing jet for XFEL study of chemical kinetics.  

PubMed

Several liquid sample injection methods have been developed to satisfy the requirements for serial femtosecond X-ray nanocrystallography, which enables radiation-damage-free determination of molecular structure at room temperature. Time-resolved nanocrystallography would combine structure analysis with chemical kinetics by determining the structures of the transient states and chemical kinetic mechanisms simultaneously. A windowless liquid mixing jet device has been designed for this purpose. It achieves fast uniform mixing of substrates and enzymes in the jet within 250?µs, with an adjustable delay between mixing and probing by the X-ray free-electron laser beam of up to 1?s for each frame of a `movie'. The principle of the liquid mixing jet device is illustrated using numerical simulation, and experimental results are presented using a fluorescent dye. PMID:25343806

Wang, Dingjie; Weierstall, Uwe; Pollack, Lois; Spence, John

2014-11-01

433

The jet divertor coils  

SciTech Connect

This paper reports on the JET Tokamak which is to be modified to incorporate a divertor. A coil system in the vacuum vessel has been developed, which can produce a range of different divertor plasmas. The divertor coils are of conventional construction and are contained in this Inconel cases. They will be assembled in the vacuum vessel, welded into their cases and impregnated with epoxy resin.

Bertolini, E.; Celentano, G.; Last, J.R.; Tait, J.; Tesini, A. (JET Joint Undertaking, Abingdon, Oxon (GB)); Dal Mut, G.; D'Urzo, C.; Ghirlanda, L.; Laurenti, A.; Maragliano, A.; Veardo, A. (Ansaldo Componenti, Genova (IT))

1992-01-01

434

Displacement amplified synthetic jets  

NASA Astrophysics Data System (ADS)

Synthetic ynthetic jet actuators are attractive devices for active flow control because, in contrast to many other actuators, they do not require a pressurized air source. Instead, they cyclically ingest and expel air from the external flow that is being controlled. To accomplish this, a piston or diaphragm is used compress and expand the volume of the actuator cavity. Various approaches to compress and expand the volume of the cavity have been explored including: speaker drivers,1 mechanical pistons2 and piezoelectric diaphragms.

Griffin, Steve; Haar, Shawn M.; Whalen, Edward

2014-03-01

435

JET Forward Programme & Opportunities for Collaboration  

E-print Network

JET Forward Programme & Opportunities for Collaboration Lorne Horton JET Exploitation Manager Contract for the Opera.on of the JET Facili.es Co-Funded by Euratom #12;L.D. Horton 2 FESAC Strategic Planning Panel 8 July 2014 - What makes JET unique! - Plans for JET exploitation

436

Jet angular momentum and quantum chromodynamics  

Microsoft Academic Search

We discuss several observable properties of hadronic final states in electron-positron annihilation that bear on the angular momentum content of jets. In particular we calculate in perturbative quantum chromodynamics the jet oblateness and the jet axis angular distribution as a function of jet invariant mass. We also consider QCD information on the PT correlation in opposite jets.

L. Clavelli

1980-01-01

437

Hydraulic Pulsed Cavitating Jet-Assisted Drilling  

Microsoft Academic Search

How to improve drilling rate in deep wells has been a hot subject. Based on modulating pulse jet and cavitating jet, a new drilling tool is designed which couples advantages of both pulse jet and cavitating jet. When drilling fluid flows through the tool during the drilling process, fluid is modulated to pulse and cavitate. Thus, pulse cavitating jet is

G. Li; H. Shi; H. Liao; Z. Shen; J. Niu; Z. Huang; H. Luo

2009-01-01

438

V+jets production at the CMS  

E-print Network

Measurements of Vector Boson production in association with jets are presented, using p-p collision data at sqrt{s} = 7 TeV. The measurements presented include Z + jets azimuthal correlations, event shapes, vector boson + jets differential cross section measurements, hard double-parton scattering using W + jets events and electroweak Z + forward - backward jet production.

B. Bilin; for the CMS Collaboration

2014-10-22

439

Synthetic Jets in Cross-flow. Part 1; Round Jet  

NASA Technical Reports Server (NTRS)

Results of an experimental investigation on synthetic jets from round orifices with and without cross-flow are presented. Jet Reynolds number up to 46,000 with a fully turbulent approach boundary layer, and Stokes number up to 400. are covered. The threshold of stroke length for synthetic jet formation. in the absence of the cross-flow, is found to be Lo /D approximately 0.5. Above Lo /D is approximately 10, the profiles of normalized centerline mean velocity appear to become invariant. It is reasoned that the latter threshold may be related to the phenomenon of saturation of impulsively generated vortices. In the presence of the cross-flow, the penetration height of a synthetic jet is found to depend on the momentum- flux ratio . When this ratio is defined in terms of the maximum jet velocity and the cross-flow velocity. not only all data collapse but also the jet trajectory is predicted well by correlation equation available for steady jets-in-cross-flow. Distributions of mean velocity, streamwise vorticity as well as turbulence intensity for a synthetic jet in cross-flow are found to be similar to those of a steady jet-in-cross-flow. A pair of counter-rotating streamwise vortices, corresponding to the bound vortex pair of the steady case, is clearly observed. Mean velocity distribution exhibits a dome of low momentum fluid pulled up from the boundary layer, and the entire domain is characterized by high turbulence.

Zaman, K. B. M. Q.; Milanovic, Ivana M.

2003-01-01

440

Intrinsically asymmetric astrophysical jets  

NASA Technical Reports Server (NTRS)

Previous work on the origin of self-collimated electromagnetic jets is extended to the general case where there is no reflection symmetry of the magnetic field about the equatorial plane of the disk. The axisymmetric field structure inside the disk is obtained by solving for the magnetic flux function, and the toroidal magnetic field, from the generalized thin-disk induction equation, which is derived. The asymptotic (large-z) magnetic field structure outside the disk is obtained by solving the force-free Grad-Shafranov equation semianalytically. Jet solutions are found in which the power flow is carried mainly by the Poynting flux of the electromagnetic field and the angular momentum outflow from the disk is carried by the magnetic field. The ratio of jet luminosities (top/bottom) depends directly on the degree of asymmetry of the field and can easily be much greater than unity. It is argued that the degree of field asymmetry in the disk is determined by the asymmetry of the weak galactic field fed into the disk at large distances over long periods of time.

Wang, J. C. L.; Sulkanen, M. E.; Lovelace, R. V. E.

1992-01-01