Sample records for plunging liquid jet

  1. Study of Air Entrainment by a Horizontal Plunging Liquid Jet

    Microsoft Academic Search

    Mario Trujillo; Suraj Deshpande; Xiongjun Wu; Georges Chahine

    2009-01-01

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

  2. Laminar Plunging Jets - Interfacial Rupture and Inception of Entrainment

    NASA Astrophysics Data System (ADS)

    Kishore, Aravind

    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.

  3. Plunging cylinder liquid piston Stirling engine

    SciTech Connect

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

    1987-06-30

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

  4. 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

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

    Microsoft Academic Search

    1984-01-01

    The use of plunging water jets can often make possible the control (and, as a consequence, the cleanup) of spilled oil and other floating pollutants in currents too swift for conventional equipment. This short, illustrated manual provides practical information for field and planning personnel on the principles of plunging water jet operation, rapid fabrication of the equipment (from readily available

  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. The hydraulic bump: The surface signature of a plunging jet

    E-print Network

    Labousse, M.

    When a falling jet of fluid strikes a horizontal fluid layer, a hydraulic jump arises downstream of the point of impact, provided a critical flow rate is exceeded. We here examine a phenomenon that arises below this jump ...

  8. The hydraulic bump: The surface signature of a plunging jet

    E-print Network

    Labousse, Matthieu

    2014-01-01

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

  9. The hydraulic bump: The surface signature of a plunging jet

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  10. Physics of liquid jets

    NASA Astrophysics Data System (ADS)

    Eggers, Jens; Villermaux, Emmanuel

    2008-03-01

    Jets, i.e. collimated streams of matter, occur from the microscale up to the large-scale structure of the universe. Our focus will be mostly on surface tension effects, which result from the cohesive properties of liquids. Paradoxically, cohesive forces promote the breakup of jets, widely encountered in nature, technology and basic science, for example in nuclear fission, DNA sampling, medical diagnostics, sprays, agricultural irrigation and jet engine technology. Liquid jets thus serve as a paradigm for free-surface motion, hydrodynamic instability and singularity formation leading to drop breakup. In addition to their practical usefulness, jets are an ideal probe for liquid properties, such as surface tension, viscosity or non-Newtonian rheology. They also arise from the last but one topology change of liquid masses bursting into sprays. Jet dynamics are sensitive to the turbulent or thermal excitation of the fluid, as well as to the surrounding gas or fluid medium. The aim of this review is to provide a unified description of the fundamental and the technological aspects of these subjects.

  11. Submerged liquid jet impingement cooling

    Microsoft Academic Search

    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

    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

  12. Whipping of electrified liquid jets

    PubMed Central

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

    2014-01-01

    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

  13. Whipping of electrified liquid jets.

    PubMed

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

    2014-09-23

    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

  14. Disintegration of a Liquid Jet

    NASA Technical Reports Server (NTRS)

    Haenlein, A

    1932-01-01

    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.

  15. The break-up of liquid jets

    Microsoft Academic Search

    A C Merrington; E G Richardson

    1947-01-01

    The mean drop size produced when a jet of liquid issuing from a nozzle into the atmosphere, breaks up, has been investigated and experiments have been carried out both with fixed nozzles and with moving nozzles (attached to an aircraft) discharging backwards. A relation expressing drop size in terms of viscosity and the relative velocity between the jet and the

  16. Liquid jet pumped by rising gas bubbles

    NASA Technical Reports Server (NTRS)

    Hussain, N. A.; Siegel, R.

    1975-01-01

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

  17. Liquid jet waveguide for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Persichetti, Gianluca; Testa, Genni; Bernini, Romeo

    2014-03-01

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

  18. Microcantilever Measurements in Microscale Liquid Jets

    NASA Astrophysics Data System (ADS)

    King, W.; Lee, J.; Berg, J.; Glezer, A.

    2004-11-01

    Thrust and heat flux in are measured in micron-scale [O(10 microns)] evaporating liquid jets by direct impingement on microfabricated atomic force microscope (AFM) microcantilever sensors. The sensors are mounted on a three-axis micropositioner and can be traversed within the near field of the jet which is simultaneously visualized using a high-magnification shadowgraph technique. The single-crystal silicon cantilevers are of two types: the first type having integrated heater/thermometer elements and the second type having integrated strain-sensing piezoresistve elements. The heater/thermometer cantilevers are calibrated in a cryostat, and can measure temperatures as low as 200K. The strain-sensing cantilevers have a measured spring constant near 1.5 N/m, and deflect up to 60 microns during jet impingement. In addition to characterization of the liquid and gaseous regimes of the jets, forced evaporation is induced by raising the heating power of the sensing element.

  19. Flapping instability of a liquid jet

    NASA Astrophysics Data System (ADS)

    Matas, Jean-Philippe; Cartellier, Alain

    2013-01-01

    We study the flapping instability observed when a liquid jet is incompletely atomized by a fast parallel gas stream: the remaining liquid jet is destabilized over a scale large compared with its radius, and breaks into liquid fragments. We characterize the symmetry of this instability and its frequency. The intact liquid length is measured as a function of gas and liquid velocity, and turns out to be longer than the one predicted by Raynal (1997) for a planar mixing layer. The frequency of the instability is measured with a spectral method, and is in agreement with the frequency observed for the planar shear instability, though slightly smaller. The planar, and not helical, symmetry of the instability makes it akin to a flapping instability, observed when a planar liquid sheet is atomized by two planar gas streams. We next measure drop sizes when the flapping instability is present, with a method based on image processing. Measured size distributions are in agreement with distributions observed in a mixing layer geometry for low gas velocities (long tail distribution). The mean drop diameter depends weakly on liquid velocity, and decreases as d10˜Ug0.9. On the contrary, Sauter diameter depends strongly on liquid velocity.

  20. Dropsize correlation for cryogenic liquid-jet atomization

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1990-01-01

    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.

  1. Effects of cavitation in a nozzle on liquid jet atomization

    Microsoft Academic Search

    Akira Sou; Shigeo Hosokawa; Akio Tomiyama

    2007-01-01

    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

  2. Investigation on the submerged liquid jet arrays impingement cooling

    Microsoft Academic Search

    Peng Tie; Qing Li; Yimin Xuan

    2011-01-01

    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

  3. Splattering during turbulent liquid jet impingement on solid targets

    SciTech Connect

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

    1994-06-01

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

  4. Breakup of liquid jets from non-circular orifices

    NASA Astrophysics Data System (ADS)

    Sharma, Priyesh; Fang, Tiegang

    2014-02-01

    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.

  5. Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas

    SciTech Connect

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

    2008-04-07

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

  6. Absolute and Convective Instability of a Liquid Jet

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  7. The Effect of Orifice Eccentricity on Instability of Liquid Jets

    NASA Astrophysics Data System (ADS)

    Amini, Ghobad; Dolatabadi, Ali

    2011-11-01

    The hydrodynamic instability of inviscid jets issuing from elliptic orifices is studied. A linear stability analysis is presented for liquid jets that includes the effect of the surrounding gas and an explicit dispersion equation is derived for waves on an infinite uniform jet column. Elliptic configuration has two extreme cases; round jet when ratio of minor to major axis is unity and plane sheet when this ratio approaches zero. Dispersion equation of elliptic jet is approximated for large and small aspect ratios considering asymptotic of the dispersion equation. In case of aspect ratio equal to one, the dispersion equation is analogous to one of the circular jets derived by Yang [1]. In case of aspect ratio approaches zero, the behavior of waves is qualitatively similar to that of long waves on a two dimensional liquid jets and the varicose and sinuous modes are predicted [2]. The growth rate of initial disturbances for various azimuthal modes has been presented in a wide range of disturbances. [4pt] [1]. Yang, H. Q. 1992 Asymmetric instability of a liquid jet. Phys. Fluids 4, 681-689. [0pt] [2]. Hagerty, W. W., Shea, J. F. 1955 A study of the stability of plane fluid sheets. J. Appl. Mech. 22, 509-514.

  8. Contraction of an inviscid swirling liquid jet: Comparison with results for a rotating granular jet.

    NASA Astrophysics Data System (ADS)

    Weidman, P. D.; Kubitschek, J. P.

    2007-11-01

    In honor of the tercentenary of Leonhard Euler, we report a new solution of the Euler equations for the shape of an inviscid rotating liquid jet emanating from a tube of inner radius R0 aligned with gravity. Jet contraction is dependent on the exit swirl parameter ?0 = R0 ?0/U0 where ?0 and U0 are the uniform rotation rate and axial velocity of the liquid at the exit. The results reveal that rotation reduces the rate of jet contraction. In the limit ?0-> 0 one recovers the contraction profile for a non-rotating jet and the limit ?0->? gives a jet of constant radius. In contrast, experiments and a kinematic model for a rotating non-cohesive granular jet show that it expands rather than contracts when a certain small angular velocity is exceeded. The blossoming profiles are parabolic in nature. The model predicts a jet of uniform radius for ?0-> 0 and a jet with an initially horizontal trajectory in the limit ?0->?.

  9. Transverse liquid fuel jet breakup, burning, and ignition

    SciTech Connect

    Li, H.

    1990-01-01

    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.

  10. Combined aerodynamic and electrostatic atomization of dielectric liquid jets

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  11. Shock wave excited liquid micro-jets

    NASA Astrophysics Data System (ADS)

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

    2006-11-01

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

  12. On transit time instability in liquid jets

    NASA Technical Reports Server (NTRS)

    Grabitz, G.; Meier, G.

    1982-01-01

    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.

  13. Flow of liquid jets through closely woven screens

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  14. Flow of liquid jets through closely woven screens

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  15. Turned trochoidal disturbance on a liquid jet surface

    NASA Astrophysics Data System (ADS)

    Sadik, Shalom; Kirzhner, Felix; Kramarenko, Denis

    2014-07-01

    This paper shows that a turned trochoidal function disturbance may lead to peripheral drops production. The resulting model is used to describe that a turned trochoidal disturbance leads to peripheral drops production on the liquid jet surface without the necessity for superimposed disturbances. The trochoid is a non-unique parametric function. Only non-unique parametric functions disturbances may lead to peripheral drops production. The trochoidal function disturbance is decomposed to Fourier series. Every Fourier element receives an amplification factor in accordance to the Rayleigh inviscid jet model. Peripheral drops are received on the jet surface. The paper shows that all trochoidal disturbance functions, prolate cycloid, cycloid and curtate cycloid have a capability of peripheral drops producing. A limited capability of peripheral drops production is introduced for the trochoidal curtate cycloid. Produced drops size are reduced for increasing the jet velocity and wave number. Smaller drops are also received by transition from the prolate cycloid to curtate cycloid disturbance.

  16. Convective heat transfer by impingement of circular liquid jets

    NASA Astrophysics Data System (ADS)

    Liu, X.; Lienhard, J. H. V.; Lombara, J. S.

    1991-08-01

    The impingement of circular, liquid jets provides a convenient method of cooling surfaces. Here, jet impingement cooling of uniformly heated surfaces is investigated analytically and experimentally for stable, unsubmerged, uniform velocity laminar jets in the absence of phase change. Analytical and numerical predictions are developed for a laminar radial film flow. Experiments using undisturbed laminar jets were performed to determine local Nusselt numbers from the stagnation point to radii of up to 40 diameters. Turbulent transition in the film flow is observed experimentally at a certain radius. Beyond this transition radius, a separate turbulent analysis is constructed. Integral method results are compared to numberical results, and Prandtl number effects are investigated. The predictions are found to agree well with the measurements for both laminar and turbulent flow. Predictive formulas are recommended for the entire range of radii.

  17. Shock wave excited liquid micro-jets

    Microsoft Academic Search

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

    2006-01-01

    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

  18. Plunge Pools in Submarine Canyons

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

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

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

    EPA Science Inventory

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

  20. Droplet collisions after liquid jet breakup in microgravity conditions

    NASA Astrophysics Data System (ADS)

    Suñol, F.; González-Cinca, R.

    2011-12-01

    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.

  1. Experimental Measurements of Rayleigh Mode Liquid Jet Breakup at Microgravity

    NASA Astrophysics Data System (ADS)

    Hudman, Michael; Lin, S. P.; Connery, Brian

    1998-11-01

    Rayleigh mode breakup of a silicone oil jet in the absence of gravity was studied experimentally at the NASA Lewis Research Center's 2.2 second drop tower. The experiment consists of an apparatus to create, measure and photograph a liquid jet in the confined space of a standard drop frame (91 x 40 x 81 cm). Reynolds and Weber numbers of around 50 were achieved. Measurements of growth rates at normal gravity and microgravity were made from photographs and the growth rates are compared to the theory of Lin and Chen.

  2. Electric field induced sheeting and breakup of dielectric liquid jets

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  3. Parametric Investigation of Liquid Jets in Low Gravity

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2005-01-01

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

  4. Jet-noise reduction through liquid-base foam injection.

    NASA Technical Reports Server (NTRS)

    Manson, L.; Burge, H. L.

    1971-01-01

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

  5. Restraint of Liquid Jets by Surface Tension in Microgravity Modeled

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2001-01-01

    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.

  6. Breakup characteristics of a liquid jet in subsonic crossflow

    NASA Astrophysics Data System (ADS)

    Gopala, Yogish

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

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

    NASA Astrophysics Data System (ADS)

    Oda, Tetsuya; Hiroyasu, Hiroyuki; Nishida, Keiya

    1993-04-01

    To elucidate deformation and breakup processes of a liquid jet across an airstream, tomograms of the liquid jet were taken by means of the laser light sheet method. In this method, fluorescent dye, Eosine-Y, was contained in the injected water, and the liquid jet was illuminated by the Nd:YAG laser light sheet. There are two types of atomization mechanisms. In the first mechanism, a horizontal section of the liquid column is distorted into a bow shape, and there exists a cavity without drops behind the liquid column. Small drops are produced at both tips of the bow. The continuous length and the width of the liquid column were measured from the tomograms. In the second mechanism, in which velocities of both the airstream and the injecting liquid are low, the liquid column is distorted in a snakelike shape and drops are produced near the tip of the liquid column.

  8. Breakup of Laminar Jet into Drops in Immiscible Liquid-Liquid Systems with Mass Transfer

    Microsoft Academic Search

    S. Homma; G. Tryggvason; J. Koga; S. Matsumoto

    1998-01-01

    The breakup of an axisymmetric jet into drops in immiscible liquid-liquid systems with mass transfer is investigated numerically. It is assumed that the solute concentration only affects the interfacial tension, so that the density and the viscosity of both phases are not influenced by the mass transfer. The axisymmetric Navier-Stokes equations, with a convection\\/diffusion equation for a single solute are

  9. Spray measurements of aerothermodynamic effect on disintegrating liquid jets

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1991-01-01

    An experimental investigation was made to determine the effect of atomizing gas mass flux and temperature on liquid jet breakup in sonic velocity gas flow. Characteristic drop size data were obtained by using the following atomizing gases: nitrogen, argon, and helium to breakup water jets in high velocity gas flow. A scattered light scanning instrument developed at Lewis Research Center was used to measure Sauter mean diameter (SMD). The three gases gave a molecular weight range of 4 to 40 and atomizing gas mass flux and temperature were varied from 6 to 50 g/sq cm and 275-400 K, respectively. The ratio of liquid jet diameter to SMD, D(sub 0)/D(sub 32), was correlated with aerodynamic and liquid-surface force ratios, i.e., the product of the Weber and Reynolds number, We Re, the gas to liquid density ratio, rho(sub g)/rho(sub 1) g and also the molecular scale dimensionless group, rho(sub 1)(Vm exp 3)/ mu(sub 1) g, to give the following expression: D(sub 0)/D(sub 32) = 0.90 x 10(exp -8) x (We Re rho sub g/rho sub 1)exp 0.44 x (rho sub 1 Vm exp 3/mu sub 1 g)exp 0.67 where We Re = ((rho sub g)exp 2(D sub 0)exp 2(V sub C)exp3))/ mu sub 1 sigma, mu sub 1 is liquid viscosity, sigma is surface tension, V sub C is the acoustic gas velocity, V sub m is the RMS velocity of gas molecules, and g is the acceleration of gas molecules due to gravity. Good agreement was obtained with atomization theory for liquid-jet breakup in the regime of aerodynamic stripping. Also, due to its low molecular weight and high acoustic velocity, helium was considerably more effective than nitrogen or argon in producing small-droplet sprays with values of D(sub 32) on the order of 5 microns.

  10. Production of jet fuel from coal-derived liquids

    SciTech Connect

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

    1987-01-01

    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.

  11. Cone-jet electrospray in a dielectric liquid atmosphere

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

    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.

  12. Nanoscale Liquid Jets Shape New Line of Business

    NASA Technical Reports Server (NTRS)

    2003-01-01

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

  13. Modeling of Turbulence Effects on Liquid Jet Atomization and Breakup

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  14. Fabrication of MEMS using liquid jet dispensing technique

    NASA Astrophysics Data System (ADS)

    Sarkisov, Sergey S.; Darwish, Abdalla M.; Abdeldayem, Hossin A.; Adamovsky, Grigory; Kulishov, Mykola B.; Banks, Curtis E.; Wang, JaChing

    1999-03-01

    We describe a simple yet efficient technique of delineation of various polymer MEMS structures using computer driven liquid jet dispenser. A syringe-type dispenser with a replaceable needle is filled with a polymer solution and mounted on a vertical translation stage. The substrate is mounted on two-coordinate horizontal translation stage. Additional vertical translation arm is connected to the plunger of the syringe. Vertical translation provides positioning of the needle at a certain height over the substrate. Delineation is accomplished when the syringe plunger, being pushed down by the vertical translation arm, dispenses the liquid on the substrate at a programmable flow rate simultaneously with horizontal motion of the substrate with respect to the needle. Horizontal motion is done along a programmable trajectory at a programmable sped. Comparing to conventional methods, the proposed device consumes three order of magnitude less amount of material for the fabrication of similar MEMS structures. In addition, we describe a supplement to the liquid delineation system in the form of a microscope objective head connected to a noncoherent UV source with a multimode optical fiber. The head can serve as a tool for UV curing of the polymer material deposited with the jet dispenser as well as a separate UV writing tool. In conclusion, we describe the calculation technique for the distribution of the electric field in electrically or optically controlled ferroelectric polymer MEMS fabricated by the proposed technique.

  15. Acoustic excitation of liquid fuel droplets and coaxial jets

    NASA Astrophysics Data System (ADS)

    Rodriguez, Juan Ignacio

    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.

  16. The Plunge Phase of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur; McClure, John; Avila, Ricardo

    2005-01-01

    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.

  17. Numerical Simulation of Liquid Jet Atomization Including Turbulence Effects

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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.

  18. The Liquid Argon Jet Trigger of the H1 Experiment at HERA

    E-print Network

    Bob Olivier

    2008-11-01

    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.

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

    Microsoft Academic Search

    Ahmed M. T Omar

    2010-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1974-01-01

    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.

  1. THE ELECTROHYDRODYNAMICS OF THE CHARGED LIQUID JET ISSUING FROM AN ELECTRIFIED TAYLOR CONE. UNIVERSAL SCALING LAWS

    Microsoft Academic Search

    Alfonso M. Gañán-Calvo

    1999-01-01

    A hybrid experimental–numerical approach to study the dynamics of capillary electrified jets, which uses a quasi-one-dimensional model and the experimentally measured shape of an actual liquid thread (Gañán-Calvo (1997) J. Fluid Mech. 335, 165–188) has been employed in this work to analyze the electrohydrodynamics of the liquid micro-jets issuing from Taylor cones. Different liquids have been used in this study,

  2. Instability of a charged non-Newtonian liquid jet

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

  3. Experimental and theoretical studies of vertical annular liquid jets

    Microsoft Academic Search

    J. I. Ramos

    1990-01-01

    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

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

    PubMed

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

    2014-05-21

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

  5. Red Giant Plunging Through Space

    NASA Technical Reports Server (NTRS)

    2006-01-01

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

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

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

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

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

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

    E-print Network

    Lee, Heejin, 1976-

    2004-01-01

    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, ...

  7. CAP-220-MUON-98R Behavior of Conducting Solid or Liquid Jet

    E-print Network

    McDonald, Kirk

    BNL 65611 CAP-220-MUON-98R June 1998 Behavior of Conducting Solid or Liquid Jet Moving in Magnetic the conductor is a cylindrical rod or rectangular bar of length l and density . The electrical resistivity as it enters the field and tends radially to disperse a conducting jet as it exits. However, unless arcing

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

    Microsoft Academic Search

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

    2006-01-01

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

  9. Liquid jet response to internal modulated ultrasonic radiation pressure and stimulated drop production.

    PubMed

    Lonzaga, Joel B; Osterhoudt, Curtis F; Thiessen, David B; Marston, Philip L

    2007-06-01

    Experimental evidence shows that a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate within the jet when the acoustic frequency is near to or above the cutoff frequency. Modulated radiation pressure is used to stimulate large amplitude deformations and the breakup of the jet into drops. The jet response to the modulated internal ultrasonic radiation pressure was monitored along the jet using (a) an optical extinction method and (b) images captured by a video camera. The jet profile oscillates at the frequency of the radiation pressure modulation and where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P.L. Marston and R.E. Apfel, J. Acoust. Soc. Am. 67, 27-37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Though aspects of the perturbation growth can be approximated from Rayleigh's analysis of the capillary instability, some detailed features of the observed jet response to modulated ultrasound are unexplained neglecting the effects of gravity. PMID:17552684

  10. Cryogenic liquid-jet breakup in two-fluid atomizers

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1991-01-01

    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.

  11. On the numerical solution of liquid film and jet flows

    NASA Astrophysics Data System (ADS)

    Pacheco, Jose Rafael

    1999-09-01

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

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

    SciTech Connect

    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

    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.

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

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1973-01-01

    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.

  14. AIR DENSITY EFFECT ON THE ATOMIZATION OF LIQUID JETS IN CROSSFLOW

    Microsoft Academic Search

    A. BELLOFIORE; A. CAVALIERE; R. RAGUCCI

    2007-01-01

    An experimental study of liquid injection in a transverse airflow at high pressure and temperature was performed. Collected shadowgraphs were processed by image statistical analysis tools. The breakdown point location was correlated to liquid-to-gas momentum ratio, gas Reynolds number and aerodynamic Weber number. The substantial uniformity of behavior of the normalized jet trajectories allowed providing an empirical correlation validated in

  15. Cavitation induced by high speed impact of a solid surface on a liquid jet

    NASA Astrophysics Data System (ADS)

    Farhat, Mohamed; Tinguely, Marc; Rouvinez, Mathieu

    2009-11-01

    A solid surface may suffer from severe erosion if it impacts a liquid jet at high speed. The physics behind the erosion process remains unclear. In the present study, we have investigated the impact of a gun bullet on a laminar water jet with the help of a high speed camera. The bullet has a flat front and 11 mm diameter, which is half of jet diameter. The impact speed was varied between 200 and 500 ms-1. Immediately after the impact, a systematic shock wave and high speed jetting were observed. As the compression waves reflect on the jet boundary, a spectacular number of vapour cavities are generated within the jet. Depending on the bullet velocity, these cavities may grow and collapse violently on the bullet surface with a risk of cavitation erosion. We strongly believe that this transient cavitation is the main cause of erosion observed in many industrial applications such as Pelton turbines.

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

    PubMed

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

    2007-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1975-01-01

    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.

  18. Analytical description of the breakup of liquid jets in air

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1993-01-01

    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.

  19. Unsteadiness of the Circulation Pattern in a Confined Liquid Jet

    Microsoft Academic Search

    S. K. A. Naib

    1966-01-01

    WHEN a turbulent jet flows through an enveloping fluid, the interface breaks up into vortices. The development of such vortices for the flow of a confined jet issuing from a sluice-way and diffusing into water downstream has previously been described1. The vortices grow as they flow downstream, and eventually extend throughout the entire height of the circulation zone. The mixing

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

    NASA Astrophysics Data System (ADS)

    Kourmatzis, A.; Shrimpton, J. S.

    2014-03-01

    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.

  1. Two-cell circulation in a liquid meniscus driven by a swirling gas jet

    NASA Astrophysics Data System (ADS)

    Herrada, Miguel A.; Shtern, Vladimir N.; López-Herrera, José María

    2011-01-01

    A liquid issuing from a capillary needle adopts a cone-jet structure if the liquid is further driven by a coflowing gas jet. In the present work, flow patterns appearing in this cone-jet structure are studied by the volume-of-fluid numerical method. Axisymmetric motions of the liquid and gas, both treated as viscous incompressible fluids, are simulated. As the gas/liquid mass ratio increases, the meridional circulation develops in the meniscus region of the liquid flow. As the ratio exceeds a threshold, the flow becomes time periodic and droplet generating. Swirl, added in the gas jet, affects the liquid flow in two ways. First, the threshold value increases with swirl. Second, the circulation region transforms from the bubble-like into ring-like pattern and then becomes two-cellular. As swirl further increases, the cells separate, one cell disappears, and a new cell emerges being attached to the needle wall. The predicted metamorphoses of the flow topology might be important for atomization of a liquid fuel.

  2. Experimental Investigation of Jet-Induced Mixing of a Large Liquid Hydrogen Storage Tank

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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 to generate an upward directed axial jet flow normal to the liquid-vapor interface. Mixing tests were initiated after achieving thermally stratified conditions in the tank either by the introduction of hydrogen gas into the tank or by self-pressurization due to ambient heat leak through the tank wall. The subcooled liquid jet directed towards the liquid-vapor interface by the mixer induced vapor condensation and caused a reduction in tank pressure. Tests were conducted at two jet submergence depths for jet Reynolds numbers from 80,000 to 495,000 and Richardson numbers from 0.014 to 0.52. Results show that the rate of tank pressure change is controlled by the competing effects of subcooled jet flow and the free convection boundary layer flow due to external tank wall heating. It is shown that existing correlations for mixing time and vapor condensation rate based on small scale tanks may not be applicable to large scale liquid hydrogen systems.

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

    NASA Astrophysics Data System (ADS)

    Strom, K. B.; Bhattacharya, J.

    2012-12-01

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

  4. X-ray diagnostics of a plasma-jet-liquid interaction in electrothermal guns

    Microsoft Academic Search

    A. Arensburg; S. Wald; S. Goldsmith

    1993-01-01

    The penetration of a plasma jet into liquid water was observed at successive time intervals by means of x-ray shadowgraphy. The plasma jet was generated by producing in a polyethylene capillary tube a high-current pulsed discharge. The tube inner diameter and length were 0.64 and 22 cm, respectively. A pulse-forming network delivered 121–182 kJ of electrical energy in 500 ?s.

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

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.

    1977-01-01

    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.

  6. Unsteady penetration of a target by a liquid jet.

    PubMed

    Uth, Tobias; Deshpande, Vikram S

    2013-12-10

    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

  7. Unsteady penetration of a target by a liquid jet

    PubMed Central

    Uth, Tobias; Deshpande, Vikram S.

    2013-01-01

    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

  8. Pursuit plunging by northern gannets (Sula bassana) \\

    Microsoft Academic Search

    Stefan Garthe; Silvano Benvenuti; William A. Montevecchi

    2000-01-01

    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-West Atlantic. We documented, for the ¢ rst time to the authors' knowledge, gannets

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

    NASA Astrophysics Data System (ADS)

    Mayer, W. O. H.

    1994-05-01

    Coaxial injectors have proven to be advantageous for the injection, atomization and mixing of propellants in cryogenic H2/O2 rocket engines. Thereby, a round liquid oxygen jet is atomized by a fast, coaxial gaseous hydrogen jet. This article summarizes phenomenological studies of coaxial spray generation under a broad variation of influencing parameters including injector design, inflow, and fluid conditions. The experimental investigations, performed using spark light photography and high speed cinematography in a shadow graph setup as main diagnostic means, illuminate the most important processes leading to atomization. These are identified as turbulence in the liquid jet, surface instability, surface wave growth and droplet detachment. Numerical simulations including free surface flow phenomena are a further diagnostic tool to elucidate some atomization particulars. The results of the study are of general importance in the field of liquid atomization.

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

    NASA Technical Reports Server (NTRS)

    Lin, S. P.

    2001-01-01

    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.

  11. Liquid-jet O2(1Delta) generator for chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Zagidullin, Marsel V.

    1995-03-01

    Results of experimental and theoretical study of the liquid jet O2(1(Delta) ) generator in P.N. Lebedev Institute Samara Branch are presented. This study includes hydrodynamic and gasdynamic effects, heat and mass transfer, droplet generation and separation. The dependence of O2(1(Delta) ) and Cl2 yields on geometrical and physical parameters of generator are presented. High O2(1(Delta) ) yield and operation of small scale subsonic chemical oxygen-iodine laser up to 100 torr of active gas pressure in jet liquid generator have been achieved. Counterflowing jet liquid O2(1(Delta) ) generator is a very perspective for high power supersonic oxygen-iodine laser without water vapor trap and droplet separator.

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

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1988-01-01

    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.

  13. Confined jet impingement of liquid nitrogen onto different heat transfer surfaces

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  14. Plunging Wave Breaking: EFD and CFD Surajeet Ghosh, George Reins, Bonguk Koo, Zhaoyuan Wang, Jianming Yang, Fred Stern

    E-print Network

    Yang, Jianming

    descriptions of the wave breaking process; energy losses; 2D and 3D vortex and turbulent structures; wave breaking process and major events: max wave height, first plunge, oblique splash-up, vertical jet, air impact; air entrainment; surf zone modeling; and multi-scale turbulence model. Tables 1 and 2 summarize

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

  16. Surface instability and primary atomization characteristics of straight liquid jet sprays

    Microsoft Academic Search

    J. Shinjo; A. Umemura

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2006-03-01

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

  18. Nanoscale, Electrified Liquid Jets for High-Resolution Printing of Charge

    E-print Network

    Rogers, John A.

    Nanoscale, Electrified Liquid Jets for High-Resolution Printing of Charge Jang-Ung Park,,,| Sangkyu by electrohydrodynamics at micro- and nanoscale nozzles to print complex patterns of both positive and negative charges the basic aspects of this process and demonstrate the capabilities through printed patterns with diverse

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

    E-print Network

    Wolper, Pierre

    is to simulate a liquid jet breakup process using openFoam, a state-of-the-art open source CFD code. Detailed that are implemented in openFoam). Set-up of a CFD model in openFoam to simulate either the fuel injection of an ISA

  20. Plunging ranula in young HIV patient.

    PubMed

    Hershkin, Adam T; Miller, Edward J

    2007-11-01

    The case of a 15-year-old African-American male with congenital HIV on highly active antiretroviral therapy (HAART) therapy with a plunging ranula who was treated with surgical removal of the offending sublingual gland and suffered no complications. This case may serve as an example that young HIV patients with this pathologic condition should be expected to have a similar course as a non-HIV patient. PMID:18265770

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

    SciTech Connect

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  3. Plunge Pools in Hawaiian Submarine Canyons

    NASA Astrophysics Data System (ADS)

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

    2001-12-01

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

  4. A focused liquid jet formed by a water hammer in a test tube

    E-print Network

    Kiyama, Akihito; Ando, Keita; Kameda, Masaharu

    2015-01-01

    We investigate motion of a gas-liquid interface in a test tube induced by a large acceleration via impulsive force. We conduct simple experiments in which the tube partially filled with a liquid falls under gravity and impacts a rigid floor. A curved gas-liquid interface inside the tube reverses and eventually forms an elongated jet (i.e. the so-called a focused jet). In our experiments, there arises either vibration of the interface or increment in the velocity of a liquid jet accompanied by the onset of cavitation in the liquid column. These phenomena cannot be explained by considering pressure impulse in a classical potential flow analysis, which does not account for finite speeds of sound as well as phase change. Here we model such water-hammer events as a result of one-dimensional pressure wave propagation and its interaction with boundaries through acoustic impedance mismatching. The method of characteristics is applied to describe pressure wave interactions and the subsequent cavitation. The proposed m...

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  6. Application of molecular simulations: Insight into liquid bridging and jetting phenomena

    E-print Network

    I. Nezbeda; J. Jirsák; F. Mou?ka; W. R. Smith

    2015-04-03

    Molecular dynamics simulations have been performed on pure liquid water, aqueous solutions of sodium chloride, and polymer solutions exposed to a strong external electric field with the goal to gain molecular insight into the structural response to the field. Several simulation methodologies have been used to elucidate the molecular mechanisms of the processes leading to the formation of liquid bridges and jets (in the production of nanofibers). It is shown that in the established nanoscale structures, the molecules form a chain with their dipole moments oriented parallel to the applied field throughout the entire sample volume. The presence of ions may disturb this structure leading to its ultimate disintegration into droplets; the concentration dependence of the threshold field required to stabilize a liquid column has been determined. Conformational changes of the polymer in the jetting process have also been observed.

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

    SciTech Connect

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

    2014-09-01

    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.

  8. Transferring jet engine diagnostic and control technology to liquid propellant rocket engines

    SciTech Connect

    Alcock, J.F.; Hagar, S.K.

    1989-01-01

    This paper presents the methodology for developing a diagnostic and control system for a current, operational jet engine. A description is given of each development stage, the system components and the technologies which could be transferred to liquid propellant rocket engines. Finally, the operational impact is described in terms of cost and maintenance based on actual jet engine experience. Efforts are continuing to develop new diagnostic techniques under IR D for application on the advanced technical fighter. Already improved techniques and application methods are becoming available. This technology is being evaluated and may also be transferred to rocket engine diagnostic and control system development.

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

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2002-01-01

    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.

  10. Ultrasound-controlled Taylor-mode breakup of liquid jets

    Microsoft Academic Search

    S. C. Tsai; P. Luu; A. Teshome; P. Childs; C. S. Tsair

    1997-01-01

    We present a resonant liquid capillary wave theory which extends Taylor's dispersion relation to include the effect of surface inclination caused by air flow. Also reported are new experimental results on effects of surface tension and air velocity on drop-size distributions in comparison to the theoretical predictions. Good agreements between the theoretical predictions and the experimental results led to the

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    A comparison of laser-induced breakdown spectroscopy (LIBS) sensitivity in laminar liquid jets and at the surface of a static liquid has been performed. Limits of detection (LODs) have been estimated for Na, Mg, Al, Ca, Ti, V, Cr, Mn, Ni, Fe, Cu, Zn, Mo, Ag, Cd, and Ba under similar conditions using both experimental arrangements. LODs in liquid jets are found to be four times lower on average compared to measurements at static surfaces. Data acquisition rates in jet experiments are also generally higher than for static liquids due to reduced problems with splashing effects. The use of LIBS in jets has also been investigated for quantitative analysis of used lubricants. A number of contaminants have been measured in a set of used engine oils and the results compared to analysis via ICP-AES, where a good correlation is obtained.

  13. Liquid jet impingement normal to a disk in zero gravity

    NASA Technical Reports Server (NTRS)

    Labus, T. L.; Dewitt, K. J.

    1978-01-01

    An experimental and analytical investigation was conducted to determine the free surface shapes of circular jets impinging normal to sharp-edged disks in zero gravity. Experiments conducted in a zero gravity drop tower yielded three distinct flow patterns which were classified in terms of the relative effects of surface tension and inertial forces. An order of magnitude analysis was conducted indicating regions where viscous forces were not significant when computing free surface shapes. The free surface analysis was simplified by transforming the governing potential flow equations and boundary conditions into the inverse plane. The resulting nonlinear equations were solved numerically and comparisons were made with the experimental data for the inertia dominated regime.

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    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.

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

    E-print Network

    Rothrock, Ray Alan

    1978-01-01

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

  16. Journal of Biomechanics 39 (2006) 25932602 The penetration of a soft solid by a liquid jet, with application

    E-print Network

    Fleck, Norman A.

    August 2005 Abstract Liquid jet injections have been performed on human skin in vivo and silicone rubber demonstrated that a sharp-tipped punch penetrates human skin and silicone rubber by the formation of a planar jet penetrates human skin and silicone rubber by the same mode I planar cracking mechanism

  17. Investigation on cone jetting regimes of liquid droplets subjected to pyroelectric fields induced by laser blasts

    NASA Astrophysics Data System (ADS)

    Gennari, Oriella; Battista, Luigi; Silva, Benjamin; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Coppola, Sara; Orlando, Pierangelo; Aprin, Laurent; Slangen, Pierre; Ferraro, Pietro

    2015-02-01

    Electrical conductivity and viscosity play a major role in the tip jetting behaviour of liquids subjected to electrohydrodynamic (EHD) forces, thus influencing significantly the printing performance. Recently, we developed a nozzle- and electrode-free pyro-EHD system as a versatile alternative to conventional EHD configurations and we demonstrated different applications, including inkjet printing and three-dimensional lithography. However, only dielectric fluids have been used in all of those applications. Here, we present an experimental characterization of the pyro-EHD jetting regimes, induced by laser blasts, of sessile drops in case of dielectric and conductive liquids in order to extend the applicability of the system to a wider variety of fields including biochemistry and biotechnology where conductive aqueous solutions are typically used.

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

    NASA Technical Reports Server (NTRS)

    Lin, Chin-Shun

    1989-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

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

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

    Microsoft Academic Search

    Avijit Bhunia; Sriram Chandrasekaran; Chung-Lung Chen

    2007-01-01

    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)],

  1. The Plunge Phase of Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    McClure, John C.

    2005-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1987-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.

    1987-01-01

    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.

  4. Flowing liquid-sheet jet for cavity ring-down absorption measurements.

    PubMed

    Alexander, A J

    2006-08-01

    The use of a flowing liquid-sheet jet in cavity ring-down absorption measurements is described. A mechanical gear pump was used to pump solvent at low pressure through a circular orifice. The resulting cylindrical jet of solvent was fired at a flat surface. A flat sheet of liquid was formed in a small portion of the resulting spray, which was sufficiently stable to be positioned at the Brewster angle in a linear ring-down cavity setup operated with a pulsed laser. The path length through a sheet-jet of ethylene glycol was measured to be 23.2 +/- 0.6 mum. Malachite Green dye was used as an analyte to demonstrate a linear dynamic range of 12.6 dB (73.9 nM to 1.34 microM). The limit of detection for the system was determined to be alpha LOD = 0.0162 cm(-1), or 71 nM (at epsilon = 9.975 x 10(4) M(-1) cm(-1), 628 nm, 3 sigma). The technique is shown to have promise for analytical and spectroscopic measurements, for example, in studies of gas-liquid interfaces. PMID:16878901

  5. Divertor target with liquid metal jet impinging upon a solid surface

    SciTech Connect

    Evtushenko, I.A.; Kirillov, I.R.; Krivchenkov, Y.M. [D.V. Efremov Scientific Research Inst. of Electrophysical Apparatus, St. Petersburg (Russian Federation)] [and others

    1994-12-31

    Free surface liquid metal flows (film and jet-droplet flows) have been investigated recently as divertor targets. They are claimed to be capable of accumulating heat fluxes up to 100 MW/m{sup 2} under reasonable liquid metal velocities. To avoid their main drawback associated with possible plasma contamination, another concept was proposed where liquid metal jet impinges upon inner surface of solid tile, facing the plasma, and flows as a thin film. The distinction from channel type flow lies in the fact that in this case the target cooling system is not hermetical and replacement of tiles can be easily achieved. The following analysis was made to prove the feasibility of this concept: thermomechanical calculations, MHD tests of mock-ups, and construction materials wettability tests. Thermomechanical analysis was made for carbon-based armor tiles cooled by LM jets from rear side. Two LM coolants (Ga and LiPb) having different initial temperatures (50{degrees}C and 280{degrees}C correspondingly) were considered at flow velocities from 0.5 to 3.0 m/s. It was shown that allowable surface temperature of the tile (<1200{degrees}C) may be kept at reasonable flow velocities and significant (>5 mm) tile thickness.

  6. Study on Breakup Length of Liquid Jet by Liquid-Gas Coaxial Injector —Evaluation of Atomization Characteristics of Rocket Engine Injectors—

    NASA Astrophysics Data System (ADS)

    Yatsuyanagi, Nobuyuki

    Based on the experimental observations using a liquid-gas coaxial injector with fairly dense liquid injection, an empirical calculation model of the breakup length of a liquid jet was derived. It is based on the one-dimensional momentum conservation equation for two-phase flow, as well as on the critical Eötvös number, which was derived experimentally by the author in a previous study. This model was applied to evaluate the local stripping rate of the liquid mass at the interaction surface between a liquid and a gas, and was applied to calculate the size of the formed droplets. Comparisons of the mean droplet size, distribution histogram of the size, and breakup length of the liquid jet were made with experimental data. This calculation model was also applied to evaluate the characteristics of the rocket injectors chosen as candidates for the LE-5, the liquid oxygen/hydrogen engine of the second stage of the Japanese H-1 launcher.

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

    NASA Astrophysics Data System (ADS)

    Wagener, Philipp; Barcikowski, Stephan

    2010-11-01

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

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

    PubMed

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

    2014-12-01

    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

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    James, Mark D.

    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.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed

    Portaro, Rocco; Ng, Hoi Dick

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Antoine, A. C.

    1977-01-01

    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.

  14. Journal of Fluid Mechanics Plunging cavities

    E-print Network

    Boyer, Edmond

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  16. Experimental Investigation of Jet Impingement Heat Transfer Using Thermochromic Liquid Crystals

    NASA Technical Reports Server (NTRS)

    Dempsey, Brian Paul

    1997-01-01

    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.

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

    PubMed

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

    2014-09-01

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

  18. Flow patterns and cleaning behaviour of stationary horizontal liquid jets impinging on angled walls

    E-print Network

    Wang, Tao; Davidson, John F.; Wilson, D. Ian

    2014-09-30

    region, which is beyond the scope of the momentum balances employed here. Numerical simulations of the free surfaces based on volume of fluid approaches, such as those described by Gunjal et al. (2005), offer promise in this area but even... , KR and Davidson, JF (2012) Surface flow and drainage films created by horizontal impinging liquid jets, Chem. Eng. Sci., 68, 449–460. 16 Nomenclature Roman c group of parameters, Eqn. [3] kg2 m-4 s-1 dN nozzle diameter m g...

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

  20. Periodically plunging foil near a free surface

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    PubMed Central

    Das, Siddhartha; Kumar, Aloke

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Das, Siddhartha; Kumar, Aloke

    2014-11-01

    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.

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

    E-print Network

    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

    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...

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

    PubMed

    Das, Siddhartha; Kumar, Aloke

    2014-01-01

    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

  6. 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...

  7. On the absence of asymmetric wakes for periodically plunging finite wings

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    It has previously been shown that, at high Strouhal numbers, oscillating airfoils can produce deflected jets that can create very high lift-coefficients for otherwise symmetric scenarios. These deflected jets form through pairing of the trailing-edge vortices to create asymmetric vortex couples that self-propel at an angle to the freestream, resulting in an asymmetric flow field and non-zero lift. In this paper results are presented that indicate these high-lift deflected jets cannot form for finite wings. Instead of the straight vortex tubes that pair and convect at an angle to the freestream observed for effectively infinite wings, finite wings exhibit vortex tubes that break into two branches near the tip forming double helix structures. One branch connects with the last vortex; one branch connects with the next vortex. This creates a long "daisy chain" of interconnected trailing edge vortices forming a long series of vortex loops. These symmetric flow fields are shown to persist for finite wings even to Strouhal numbers more than twice those required to produce asymmetric wakes on plunging airfoils. Two contributing reasons are discussed for why deflected jets are not observed. First the tip vortex creates three-dimensionality that discourages vortex coupling. Second, the symmetry of the circulation of the interconnected vortex loops, which has been confirmed by the experiments, is a natural consequence of the vortex topology. Therefore, the asymmetry in trailing edge vortex strength previously observed as characteristic of deflected jets cannot be supported for finite wings.

  8. Liquid crystal alignment on aC:H films by an argon plasma jet at atmospheric pressure

    Microsoft Academic Search

    H. K. Wei; C. S. Kou; K. Y. Wu; J. Hwang

    2008-01-01

    A novel liquid crystal alignment method has been successfully developed. The alignment layer was made of a hydrogenated amorphous carbon film (a-C:H). At atmospheric pressure, the surface of the film was treated by a low temperature argon plasma jet. Experimental results showed that uniform alignment of the liquid crystal (ZLI-2293) has been achieved with a pretilt angle of 2.32° in

  9. Scattered-light scanner measurements of cryogenic liquid-jet breakup

    NASA Technical Reports Server (NTRS)

    Ingebo, Robert D.; Buchele, Donald R.

    1990-01-01

    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.

  10. Scattered-light scanner measurements of cryogenic liquid-jet breakup

    NASA Astrophysics Data System (ADS)

    Ingebo, Robert D.; Buchele, Donald R.

    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.

  11. Laminar jets of Bingham-plastic liquids K. R. J. Ellwood,a) G. C. Georgiou, T. C. Papanastasiou, and

    E-print Network

    Georgiou, Georgios

    Laminar jets of Bingham-plastic liquids K. R. J. Ellwood,a) G. C. Georgiou, T. C. Papanastasiou the yield stress. These materials are often called Bingham plastics, after Bingham,' who first described paint in this way in 1919, and were first analyzed by Oldroyd,2 Reiner,3 and Prager.4 Paint, slurries

  12. Modeling the Restraint of Liquid Jets by Surface Tension in Microgravity

    NASA Technical Reports Server (NTRS)

    Chato, David J.; Jacqmim, David A.

    2001-01-01

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

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

    SciTech Connect

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

    1980-12-01

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

  14. Detailed simulation of atomizing liquid jets using a Spectrally Refined Interface (SRI) approach

    NASA Astrophysics Data System (ADS)

    Pitsch, Heinz; Desjardins, Olivier

    2008-11-01

    Simulating primary atomization remains an outstanding challenge due to the presence of turbulence, small scale liquid structures, and singular surface tension forces. A new approach is presented that employs sub-cell quadrature nodes to provide a high order polynomial reconstruction of a level set function. This Spectrally Refined Interface (SRI) description is coupled to semi-Lagrangian transport to alleviate the small time step requirements usually associated with local refinement, and is combined with the Ghost Fluid Method (GFM) to accurately and robustly handle the discontinuous material properties in the two phases, as well as surface tension forces. This technique is validated over a range of test cases and is shown to provide a very accurate description of the interface even at the limit of numerical resolution. Highly detailed simulations of atomizing two-phase jets are conducted, and the physical processes occurring during atomization are discussed.

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

    SciTech Connect

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

    2007-08-13

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

  16. Effect of liquid droplets on turbulence in a round gaseous jet

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    The main objective of this investigation is to develop a two-equation turbulence model for dilute vaporizing sprays or in general for dispersed two-phase flows including the effects of phase changes. The model that accounts for the interaction between the two phases is based on rigorously derived equations for turbulence kinetic energy (K) and its dissipation rate epsilon of the carrier phase using the momentum equation of that phase. Closure is achieved by modeling the turbulent correlations, up to third order, in the equations of the mean motion, concentration of the vapor in the carrier phase, and the kinetic energy of turbulence and its dissipation rate for the carrier phase. The governing equations are presented in both the exact and the modeled formes. The governing equations are solved numerically using a finite-difference procedure to test the presented model for the flow of a turbulent axisymmetric gaseous jet laden with either evaporating liquid droplets or solid particles. The predictions include the distribution of the mean velocity, volume fractions of the different phases, concentration of the evaporated material in the carrier phase, turbulence intensity and shear stress of the carrier phase, droplet diameter distribution, and the jet spreading rate. The predictions are in good agreement with the experimental data.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    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.

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

    SciTech Connect

    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

    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.

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

    E-print Network

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

    2013-11-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  1. Anaesthetic management in a case of huge plunging ranula

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Olanrewaju, Babajide O.

    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

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

    NASA Astrophysics Data System (ADS)

    Hassan, Ezeldin A.

    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.

  4. Underlying principle of efficient propulsion in flexible plunging foils

    NASA Astrophysics Data System (ADS)

    Zhu, Xiao-Jue; He, Guo-Wei; Zhang, Xing

    2014-12-01

    Passive flexibility was found to enhance propulsive efficiency in swimming animals. In this study, we numerically investigate the roles of structural resonance and hydrodynamic wake resonance in optimizing efficiency of a flexible plunging foil. The results indicates that (1) optimal efficiency is not necessarily achieved when the driving frequency matches the structural eigenfrequency; (2) optimal efficiency always occurs when the driving frequency matches the wake resonant frequency of the time averaged velocity profile. Thus, the underlying principle of efficient propulsion in flexible plunging foil is the hydrodynamic wake resonance, rather than the structural resonance. In addition, we also found that whether the efficiency can be optimized at the structural resonant point depends on the strength of the leading edge vortex relative to that of the trailing edge vortex. The result of this work provides new insights into the role of passive flexibility in flapping-based propulsion.

  5. Image analysis of jet structure on electrospinning from free liquid surface

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  6. Image analysis of jet structure on electrospinning from free liquid surface

    SciTech Connect

    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

    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.

  7. Stability and contraction of a rectangular liquid metal jet in a vacuum environment

    Microsoft Academic Search

    A. I Konkachbaev; N. B Morley; K Gulec; T Sketchley

    2000-01-01

    Hydrodynamic similarity criteria and experimental data are reported here from experiments underway at UCLA that simulate the slab jets of the HYLIFE-II inertial fusion reactor. The current experimental setup produces a 2×20 mm slab jet, and reaches a maximum Reynolds number 5×104, corresponding to a jet velocity of 12 m\\/s. A high-speed camera is used to obtain and analyze data.

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

    SciTech Connect

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

    2005-12-01

    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.

  9. Transitions in the vortex wake behind the plunging profile

    NASA Astrophysics Data System (ADS)

    Koz?owski, Tomasz; Kudela, Henryk

    2014-12-01

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

  10. Effect of spanwise flexibility on aerodynamics of a plunging wing

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  11. 2D laser diagnostics of liquid methanol for investigation of atomization and vaporization dynamics in a burning spray jet

    SciTech Connect

    Bazile, R.; Stepowski, D. [Univ. of Rouen, Mont Saint Aignan (France)

    1994-12-31

    Single-shot planar imaging of Raman scattering of liquid methanol, as well as laser-induced fluorescence of dissolved dye, has been used to investigate atomization and vaporization dynamics in the early stages of a burning spray jet. Within the limited dynamic range of the camera, these linear techniques provide signal levels that are locally proportional to the mass of liquid intercepted by the laser sheet, whereas the techniques based on elastic interactions with the spray could not provide quantifiable data in this region of large size dispersion. High-speed 2D maps of the condensed mass held of the initial jet display the dynamic behavior of the structures induced by different regimes of air-blast atomization. The technique has enabled them to obtain planar instantaneous pictures of the liquid phase velocity field in the early development of the burning spray. When a droplet vaporizes, the signal level on its (blue) Raman image scales as its actual volume d{sup 3}, whereas the signal level on its (red) dye fluorescence image scales as its initial volume d{sub 0}{sup 3}, since the mass of dissolved dye does not vaporize. The comparison of the simultaneous images provides useful information on the vaporization dynamics in the burning spray. The data have been obtained in terms of evaporation constant from size reduction of single droplets or in terms of vaporized mass fraction of injected fuel from integrated measurements.

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

    SciTech Connect

    Shumway, R.W.

    1997-05-01

    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.

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

    SciTech Connect

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

    2014-08-01

    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.

  14. Optimal Control of Cylindrical Plunge Grinding Using Dynamic Programming

    NASA Astrophysics Data System (ADS)

    Choi, Jeongju

    An optimal grinding control scheme for cylindrical plunge grinding is proposed in this paper. The proposed grinding control scheme provides the optimal dressing and grinding parameters for batch production. The proposed control scheme consists of a G.A. (Genetic Algorithm) and dynamic programming. The optimized grinding parameters, in accordance with the state variable per cycle, are determined by the G.A. and dynamic programming is applied to ascertain the optimal grinding and dressing parameters for the overall batch. To evaluate the performance of the proposed scheme, off-line simulations based on the experimental data are conducted.

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

    SciTech Connect

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

    2011-11-20

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

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

    SciTech Connect

    Mansour, A.; Chigier, N.

    1993-12-01

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

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

    Microsoft Academic Search

    Shirley C. Tsai; Patrick Luu; P. Childs; Chen S. Tsai

    1999-01-01

    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

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

    E-print Network

    Weeks, Eric R.

    of Newtonian fluids, including mineral oil poured by hand. A thin layer of air separates the bouncing jet from on the surface prior to coalescing 4 , float without ever coalesc- ing 5 , or break into droplets 6 . We report be seen to sit on the water surface momentarily. During this time of noncoalescence, a thin layer of air

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

    Microsoft Academic Search

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

    1984-01-01

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

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

    E-print Network

    to convert it to steel known as the basic oxygen conversion process1 . In the arc welding process, a high applications, such as in the steel industry, where a supersonic jet of oxygen impinges on molten iron the stability and efficiency by limiting the welding speed.2 While entrainment is a viscous effect, the normal

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

    NASA Astrophysics Data System (ADS)

    Gomez, Guillermo Andres

    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.

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

    NASA Astrophysics Data System (ADS)

    Bazile, R.; Stepowski, D.

    1995-11-01

    Planar LIF of acetone has been performed in the near development field of a burning spray jet. The main difficulty of such investigations comes from the large range of signal levels provided by the vapor and the size dispersed spray, which cannot be covered by the camera dynamics. The key point of the present work lies in a strong compression of the fluorescence signal dynamics as the UV laser radiation is strongly absorbed by the liquid phase. Preliminary experiments were made in homogeneous vapor and with calibrated drops to quantify the acetone fluorescence signals. Analysis of the histograms of signal level in the spray shows that a cut-off signal level can be used to reject the contribution of the liquid phase. The single shot fluorescence profiles have been processed to restore the fields of fluctuating and mean concentration of acetone vapor in the spray. The liquid concentration field was obtained by extracting the individual drops data from the single shot fluorescence images with a reduced gain of the camera. A statistical correction accounting for the discrete extinctions of the laser by the drops has been used. Analysis of the results shows the influence of the input atomization parameters on the structures of the condensed and vaporized concentration fields.

  3. Volume163,number 43 CHEMICAL PHYSICS LETTERS I7 November 1989 STUDIES OF MOLECULAR PROPERTIES AT THE SURFACE OF A LIQUID JET

    E-print Network

    Eisenthal, Kenneth B.

    Volume163,number 43 CHEMICAL PHYSICS LETTERS I7 November 1989 STUDIES OF MOLECULAR PROPERTIES of a flowing jet. Measurements of the SH signal strength and the polarization of the SH light at various- ecules at the liquid interface that exit the glass nozzle is determined by the nitrophenol interactions

  4. Categorization of flow structures around a pitching and plunging airfoil

    NASA Astrophysics Data System (ADS)

    Fenercioglu, Idil; Cetiner, Oksan

    2012-05-01

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

  5. Mixing and chemical reaction at high Schmidt number near turbulent/nonturbulent interface in planar liquid jet

    NASA Astrophysics Data System (ADS)

    Watanabe, T.; Naito, T.; Sakai, Y.; Nagata, K.; Ito, Y.

    2015-03-01

    This study investigates the mixing of reactive species at a high Schmidt number (Sc ? 600) near the turbulent/nonturbulent (T/NT) interface in a planar liquid jet with a chemical reaction A + B ? R. Reactants A and B are supplied from the jet and ambient flows, respectively. An I-type hot-film probe and optical fiber probe are used for the simultaneous measurements of the streamwise velocity, mixture fraction, and concentrations of all reactive species and for detecting the T/NT interface. Statistics conditioned on the time elapsed after interface detection are analyzed. The conditional mean mixture fraction and concentrations change sharply near the interface. The widths of these changes are independent of the chemical species. The conditional statistics reveal the dependence of the chemical reaction on the interface orientation. The segregation intensity near the interface shows that the mixing state of the two reactants also depends on the interface orientation. However, the large reaction rate near the interface is related to the large concentration of reactant A rather than the mixing state, because reactant A supplied from the jet tends to be deficient near the interface. Near the interface where the reaction rate is large, the concentration of the chemical product is also large. The difference in the product concentration between the different interface orientations is larger for the infinitely fast reaction (as investigated by using the equilibrium limit) than the finite Damköhler number case, and the dependence of the chemical reaction on the interface orientation is expected to be significant for a fast chemical reaction.

  6. Flow structure and performance of a flexible plunging airfoil

    NASA Astrophysics Data System (ADS)

    Akkala, James Marcus

    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.

  7. Experimental application of pulsed Ho:YAG laser-induced liquid jet for neuroendoscopic hematoma removal

    NASA Astrophysics Data System (ADS)

    Ohki, T.; Nakagawa, A.; Sato, J.; Jokura, H.; Hirano, T.; Sato, Y.; Uenohara, H.; Sun, M.; Tominaga, T.; Takayama, K.

    To develop the novvel device for neuroendoscopic hematoma removal, we describe the Ho:YAG laser-induced liquiud jet system for hematoma fragmentation and liquefaction. Two types of nozzle were used (nozzle 1: internal diameter: 200 ?m, nozzle 2: internal diameter: 1000 ?, each length: 5mm) and the pressure profiles of LILJ ejected from those nozzles were measured. And also the effectiveness of present system was evaluated by calculating liquefaction rate (measured as the percentage of the weight loss of the treated artificial hematoma) in vitro experiments.

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

    E-print Network

    Flores Cervantes, Javier Homero, 1977-

    2004-01-01

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

  9. Augmentation of Critical Heat Flux of High Velocity Liquid Jet Flow utilizing Flat-Narrow Rectangular Channel

    NASA Astrophysics Data System (ADS)

    Sakurai, Hisashi; Koizumi, Yasuo; Ohtake, Hiroyasu

    Sub-cooled flow boiling heat transfer experiments were performed for narrow-flat flow passages of 2 mm wide and 0.2 mm high. A heat transfer surface of 2 mm × 2 mm was placed at the just downstream of the flow channel outlet. A fast wall plane-jet was formed on the heat transfer surface and space for vapor generated on the heat transfer surface to leave freely form the plane jet was provided The experiments covered the flow rate from 5 m?s through 20 m?s and the inlet sub-cooling from 30 K through 70 K. Critical heat fluxes were greatly augmented about twice compared with those in the previous experiments where the heat transfer surface was located at the outlet end of the same flow channel as that in the present experiments. This has indicated that the present idea of the flow system is effective to enhance the critical heat flux. When the flow velocity was slower than 10 m?s, a large secondary bubble that was formed as a result of coalescence of many primary bubbles on the heat transfer surface covered the heat transfer surface. The large-coalesced bubble triggered the occurrence of the critical heat flux. When the flow velocity became faster than 10 m?s, the heat transfer surface was covered with many tiny-primary bubbles even at the critical heat flux condition. The critical heat fluxes in the present experiments were much larger than predictions of correlations. The triggering mechanism of the critical heat flux condition was proposed based on the observation mentioned above. It has two parts; for low flow velocity and for high flow velocity. The boundary is 10 m?s. In both cases, disappearance of a liquid film under the bubble due to evaporation is related to the appearance of the critical heat flux condition. The predicted critical heat fluxes were larger than that measured, however, qualitatively agreed well.

  10. Transition from inspiral to plunge for eccentric equatorial Kerr orbits

    E-print Network

    R. O'Shaughnessy

    2002-11-07

    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.

  11. Interactive graphics system for locating plunge electrodes in cardiac MRI images

    NASA Astrophysics Data System (ADS)

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

    1991-05-01

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

  12. The Rayleigh-Plateau instability and jet formation during the extrusion of liquid metal from craters in a vacuum arc cathode spot

    NASA Astrophysics Data System (ADS)

    Mesyats, G. A.; Zubarev, N. M.

    2015-01-01

    We consider the displacement of molten metal from a crater being formed on the cathode during the operation of a vacuum arc under the pressure of the cathode plasma and formulate a criterion for the formation of a thin ridge of expelled liquid metal (a sheet-like jet) at the crater edge. When the ridge height is substantially greater than its thickness, conditions arise for the development of the Rayleigh-Plateau capillary instability, which breaks the axial symmetry of the problem. Estimates are presented, which suggest that this instability is responsible for the breakup of the liquid ridge into jets, which play an important role in the self-sustained operation of a discharge.

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

    Microsoft Academic Search

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

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

  14. 5-20 keV laser-induced x-ray generation at 1 kHz from a liquid-jet target

    Microsoft Academic Search

    R. J. Tompkins; I. P. Mercer; M. Fettweis; C. J. Barnett; D. R. Klug; Lord G. Porter; I. Clark; S. Jackson; P. Matousek; A. W. Parker; M. Towrie

    1998-01-01

    We report ultrashort pulse, 1 kHz repetition rate x-ray generation in the 5-20 keV spectral region, induced by the interaction of laser radiation with copper nitrate solution and ethylene glycol liquid-jet targets. The characteristics of the copper nitrate source are relevant for application to time-resolved x-ray diffraction studies as well as for spectroscopic x-ray absorption studies. The x-ray sources were

  15. Effect of exhaust gas recirculation on emissions from a flame-tube combustor using Liquid Jet A fuel

    NASA Technical Reports Server (NTRS)

    Marek, C. J.; Tacina, R. R.

    1976-01-01

    The effects of uncooled exhaust gas recirculation as an inert diluent on emissions of oxides of nitrogen (NO + NO2) and on combustion efficiency were investigated. Ratios of recirculated combustion products to inlet airflow were varied from 10 to 80 percent by using an inlet air ejector nozzle. Liquid Jet A fuel was used. The flame-tube combustor was 10.2 cm in diameter. It was operated with and without a flameholder present. The combustor pressure was maintained constant at 0.5 MPa. The equivalence ratio was varied from 0.3 to 1.0. The inlet air temperature was varied from 590 to 800 K, and the reference velocity from 10 to 30 m/sec. Increasing the percent recirculation from 10 to 25 had the following effects: (1) the peak NOx emission was decreased by 37 percent, from 8 to 5 g NO2/kg fuel, at an inlet air temperature of 590 K and a reference velocity of 15 m/sec; (2) the combustion efficiency was increased, particularly at the higher equivalence ratios; and (3) for a high combustion efficiency of greater than 99.5 percent, the range of operation of the combustor was nearly doubled in terms of equivalence ratio. Increasing the recirculation from 25 to 50 percent did not change the emissions significantly.

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

    SciTech Connect

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

    2013-02-15

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

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

    PubMed

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

    2014-06-01

    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

  18. Hydro-physical processes at the plunge point: an analysis using satellite and in situ data

    NASA Astrophysics Data System (ADS)

    Assireu, A. T.; Alcântara, E.; Novo, E. M. L. M.; Roland, F.; Pacheco, F. S.; Stech, J. L.; Lorenzzetti, J. A.

    2011-12-01

    The plunge point is the main mixing point between river and epilimnetic reservoir water. Plunge point monitoring is essential for understanding the behavior of density currents and their implications for reservoir. The use of satellite imagery products from different sensors (Landsat TM band 6 thermal signatures and visible channels) for the characterization of the river-reservoir transition zone is presented in this study. It is demonstrated the feasibility of using Landsat TM band imagery to discern the subsurface river plumes and the plunge point. The spatial variability of the plunge point evident in the hydrologic data illustrates the advantages of synoptic satellite measurements over in situ point measurements alone to detect the river-reservoir transition zone. During the dry season, when the river-reservoir water temperature differences vanish and the river circulation is characterized by interflow-overflow, the river water inserts into the upper layers of the reservoir, affecting water quality. The results indicate a good agreement between hydrologic and satellite data and that the joint use of thermal and visible channel data for the operational monitoring of a plunge point is feasible. The deduced information about the density current from this study could potentially be assimilated into numerical models and hence be of significant interest for environmental and climatological research.

  19. 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)

    Tan, Benjamin

    1995-01-01

    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.

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

    SciTech Connect

    Stevens, J.; Pan, Y.; Webb, B.W. (Brigham Young Univ., Provo, UT (United States))

    1992-11-01

    This study characterized the mean and fluctuating parts of the radial component of the local velocity in the stagnation region of an impinging, free-surface liquid jet striking a smooth flat plate. Four different nozzle exit conditions were studied, including fully developed pipe flow, a contoured nozzle, and turbulence-damped and undamped sharp-edged orifices. Liquid jet Reynolds numbers in the range 30,000 to 55,000 were investigated. Velocities were measured using laser-Doppler velocimetry. Mean velocities were found to vary nearly linearly with radial location, with the slope of the line being a function of distance from the impingement plate. Dimensionless mean velocity gradients, of relevance to the heat transfer, were found to be a strong function of nozzle type, but roughly independent of jet Reynolds number for a given nozzle type. Turbulence levels were also found to be strongly influenced by the nozzle exit-condition. Local heat transfer data corresponding to the flow structure measurements presented here are reported in Part 2 of this study. 22 refs., 9 figs.

  1. Effect of nozzle configuration on transport in the stagnation zone of axisymmetric, impinging free-surface liquid jets: Part 2-local heat transfer

    SciTech Connect

    Pan, Y.; Stevens, J.; Webb, B.W. (Brigham Young Univ., Provo, UT (United States))

    1992-11-01

    This is the second of a two-part study on the flow structure and heat transfer characteristics of turbulent, free-surface liquid jets. Part 2 deals with the effect of selected nozzle configurations on the local heat transfer in the stagnation zone. Infrared techniques have been used to characterize the local heat transfer for the four nozzle configurations whose mean and turbulent flow structure was detailed in Part 1. The results show that for identical jet Reynolds numbers, significant differences exist in the magnitudes of the local Nusselt number for the nozzle types studied. Differences of approximately 40 percent were observed. Local heat transfer results reveal that for already turbulent jets, the mean radial velocity gradient appears to be more influential in determining the heat transfer than incremental changes in the level of turbulence (as measured by the radial component of the fluctuations). An empirical correlation of the experimental data supports this conclusion, and reveals that the stagnation Nusselt number is affected independently by the jet Reynolds number and the dimensionless mean radial velocity gradient. 21 refs., 6 figs.

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

    NASA Technical Reports Server (NTRS)

    Carta, F. O.

    1979-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

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

    PubMed

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

    2013-09-01

    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

  5. Atomization by jet impact

    Microsoft Academic Search

    N. Bremond; E. Villermaux

    2006-01-01

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

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

    E-print Network

    GEOLOGY, December 2009 1067 ABSTRACT Hyperpycnal flows are turbid river plumes that can plunge to form turbidity currents where they enter a water body of lesser den- sity. Because these flows provide-dimensional flow model and found that turbid river flow must move through a back- water zone, depth-limited plume

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

    E-print Network

    Hogg, Andrew

    Occurrence and origin of submarine plunge pools at the base of the US continental slope Simon E to reduced bed shear stress downstream of hydraulic jumps in submarine sediment-laden density flows £ows; continental slope; morphology; hydraulic jump 1. Introduction Submarine sediment-laden density

  8. Too Fast, Too Furious: A Galaxy's Fatal Plunge

    NASA Astrophysics Data System (ADS)

    2004-01-01

    Trailing 200,000-light-year-long streamers of seething gas, a galaxy that was once like our Milky Way is being shredded as it plunges at 4.5 million miles per hour through the heart of a distant cluster of galaxies. In this unusually violent collision with ambient cluster gas, the galaxy is stripped down to its skeletal spiral arms as it is eviscerated of fresh hydrogen for making new stars. The galaxy's untimely demise is offering new clues to solving the mystery of what happens to spiral galaxies in a violent universe. Views of the early universe show that spiral galaxies were once much more abundant in rich clusters of galaxies. But they seem to have been vanishing over cosmic time. Where have these "missing bodies" gone? Astronomers are using a wide range of telescopes and analysis techniques to conduct a "CSI" or Crime Scene Investigator-style look at what is happening to this galaxy inside its cluster's rough neighborhood. "It's a clear case of galaxy assault and battery," says William Keel of the University of Alabama. "This is the first time we have a full suite of results from such disparate techniques showing the crime being committed, and the modus operandi." Keel and colleagues are laying out the "forensic evidence" of the galaxy's late life, in a series of presentations today in Atlanta, Ga., at the 203rd meeting of the American Astronomical Society. Astronomers have assembled the evidence by combining a variety of diagnostic observations from telescopes analyzing the galaxy's appearance in X-ray, optical, and radio light. Parallel observations at different wavelengths trace how stars, gas, and dust are being tossed around and torn from the fragile galaxy, called C153. Though such "distressed" galaxies have been seen before, this one's demise is unusually swift and violent. The galaxy belongs to a cluster of galaxies that slammed into another cluster about 100 million years ago. This galaxy took the brunt of the beating as it fell along a trajectory straight through the dense core of the colliding cluster. "This helps explain the weird X-ray and radio emissions we see," says Keel. "The galaxy is a laboratory for studying how gas can be stripped away when it flies through the hot cluster gas, shutting down star birth and transforming the galaxy." The first suggestion of galactic mayhem in this cluster came in 1994 when the Very Large Array radio telescope near Socorro, N.M., detected an unusual number of radio galaxies in the cluster, called Abell 2125. Radio sources trace both star formation and the feeding of central black holes in galaxy clusters. The radio observations also showed that C153 stood out from the other galaxies as an exceptionally powerful radio source. Keel's team began an extensive program of further observations to uncover details about the galaxies. "This was designed to see what the connection could possibly be between events on the 10-million-light-year scale of the cluster merger and what happens deep inside individual galaxies," says Keel. X-ray observations from the ROSAT satellite (an acronym for the Roentgen Satellite) demonstrated that the cluster contains vast amounts of 36-million-degree Fahrenheit (20-million-degree Kelvin) gas that envelops the galaxies. The gas is concentrated into two main lumps rather than smoothly distributed across the cluster, as is more commonly the case. This bolstered the suspicion that two galaxy clusters are actually colliding. In the mid-to-late 1990s astronomers turned the Mayall 4-meter telescope and the WIYN 3.5-meter telescope at the Kitt Peak National Observatory on the cluster to analyze the starlight via spectroscopy. They found many star-forming systems and even active galactic black holes fueled by the collision. The disintegrating galaxy C153 stood out dramatically when the KPNO telescopes were used to photomap the cluster in color. Astronomers then trained NASA's Hubble Space Telescope (HST) onto C153 and resolved a bizarre shape. They found that th

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

    SciTech Connect

    CONNER, J.M.

    2003-07-01

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

  10. 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)

    Lallave Cortes, Jorge C.

    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.

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

    Microsoft Academic Search

    R. Bazile; D. Stepowski

    1995-01-01

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

  12. Experimental investigation on transfer characteristics of temperature fluctuation from liquid sodium to wall in parallel triple-jet

    Microsoft Academic Search

    Nobuyuki Kimura; Hiroyuki Miyakoshi; Hideki Kamide

    2007-01-01

    A quantitative evaluation on thermal striping, in which temperature fluctuation due to convective mixing causes thermal fatigue in structural components, is of importance for integrity of nuclear reactors and also general plants. Sodium cooled fast reactor had also several incidents of coolant leakage due to the high cycle thermal fatigue. A sodium experiment of parallel triple-jet configuration was performed to

  13. Force prediction and stability analysis of plunge milling of systems with rigid and flexible workpiece

    Microsoft Academic Search

    Ahmed Damir; Eu-Gene Ng; Mohamed Elbestawi

    2011-01-01

    Time domain simulation model is developed to study the dynamics of plunge milling process for system with rigid and flexible\\u000a workpiece. The model predicts the cutting forces, system vibration as a function of workpiece and tool dynamics, tool setting\\u000a errors, and tool kinematics and geometry. A horizontal approach is used to compute the chip area to consider the contribution\\u000a of

  14. Thermal Tolerance Limits of Diamondback Moth in Ramping and Plunging Assays

    PubMed Central

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Means, Steven L.; Heitmeyer, Richard M.

    2002-08-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Vassilakos, Gregory J.

    2014-01-01

    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.

  17. IR and UV spectroscopy of vapor-phase jet-cooled ionic liquid [emim]+ [Tf2N]-: ion pair structure and photodissociation dynamics.

    PubMed

    Cooper, Russell; Zolot, Alexander M; Boatz, Jerry A; Sporleder, David P; Stearns, Jaime A

    2013-11-27

    Small gas-phase clusters (ion pairs) of the ionic liquid [emim](+)[Tf2N](-) have been generated in a supersonic expansion. Clusters are investigated via UV photofragmentation and time-of-flight mass spectrometry. Spectra between 42,000 and 45,000 cm(-1) reveal dynamical branching between direct dissociation of the ion pair to the cation and anion and to radical species. The IR spectrum between 2800 and 3200 cm(-1) was measured by action spectroscopy. Multiple conformations of the ion pair are found to be present in the molecular beam, leading to broad spectral features, further complicated by hydrogen bonding and Fermi resonances. The measured and theoretical spectra compare well, and the jet-cooled ion pair structures present in the molecular beam are strongly hydrogen bonded "stacked" conformers. PMID:24175625

  18. Experimental study of gravity-driven dense suspension jets

    Microsoft Academic Search

    Maxime Nicolas; Technopole de Chateau-Gombert

    2002-01-01

    This article presents experimental results from a study of a jet of dense suspension falling under gravity in a quiescent liquid bath of miscible liquid. The initial jet velocity v0 scales with the square of the initial jet diameter. Four different flow behaviors are observed. The jet remains cylindrical and stable when viscous forces are dominant. A capillary-like instability with

  19. Jet Streams

    NSDL National Science Digital Library

    COMET

    2012-11-13

    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.

  20. The role of jet inlet geometry in impinging jet heat transfer, modeling and experiments

    Microsoft Academic Search

    M. F. Koseoglu; S. Baskaya

    2010-01-01

    Effects of jet inlet geometry and aspect ratio on local and average heat transfer characteristics of totally nine confined impinging jets have been investigated experimentally using thermochromic liquid crystals and numerically by using a 3-D low Reynolds number k–? model. Experimental study by using liquid crystals for temperature measurement was conducted for three different jet exit geometries (circular, elliptic, rectangular).

  1. 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)

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

    2005-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    McGowan, Gregory Z.

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

  3. Viscoelasticity breaks the symmetry of impacting jets.

    PubMed

    Lhuissier, H; Néel, B; Limat, L

    2014-11-01

    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

  4. Viscoelasticity Breaks the Symmetry of Impacting Jets

    NASA Astrophysics Data System (ADS)

    Lhuissier, H.; Néel, B.; Limat, L.

    2014-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

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

    NASA Technical Reports Server (NTRS)

    Bratanow, T.; Ecer, A.

    1973-01-01

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

  7. Higher-Order Spectral Analysis of a Nonlinear Pitch and Plunge Apparatus

    NASA Technical Reports Server (NTRS)

    Silva, Walter A.; Strganac, Thomas W.; Hajj, Muhammad R.

    2005-01-01

    Simulated aeroelastic responses of a nonlinear pitch and plunge apparatus are analyzed using various statistical signal processing techniques including higher-order spectral methods. A MATLAB version of the Nonlinear Aeroelastic Testbed Apparatus (NATA) at the Texas A&M University is used to generate various aeroelastic response data including limit cycle oscillations (LCO). Traditional and higher-order spectral (HOS) methods are applied to the simulated aeroelastic responses. Higher-order spectral methods are used to identify critical signatures that indicate the transition from linear to nonlinear (LCO) aeroelastic behavior.

  8. Plunge Video

    NSDL National Science Digital Library

    Gene Feldman

    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.

  9. Jet shielding of jet noise

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  10. Jet pump assisted artery

    NASA Technical Reports Server (NTRS)

    1975-01-01

    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.

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

    SciTech Connect

    Hoffman, M.A.

    1982-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

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

    PubMed

    Dolezalova, Eva; Lukes, Petr

    2015-06-01

    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

  14. Optimization of anaerobic co-digestion of olive mill wastewater and liquid poultry manure in batch condition and semi-continuous jet-loop reactor.

    PubMed

    Khoufi, Sonia; Louhichi, Assawer; Sayadi, Sami

    2015-04-01

    Anaerobic co-digestion of olive mill wastewater (OMW) with liquid poultry manure (LPM) was investigated in a jet-loop reactor (JLR) as a new approach for upgrading the efficiency of bioprocess. Optimum proportion of LPM was evaluated by determining biochemical methane potential. Methane yields were compared by applying one way ANOVA method followed by post hoc Tukey's test with a 0.05 significance level. Results demonstrated that the addition of LPM at proportion of 10% and 30% (v/v) improved methane yield of OMW digestion but differences between these mixtures and raw OMW are not significant. JLR results confirmed that the proportion 30% LPM gives the optimum condition for excellent stability of digester. Methane production was significantly high until an organic loading rate of 9.5gCOD/Lreactor/day. Overall; this study indicates the technical feasibility and effectiveness of using JLR as one-stage anaerobic system for the co-digestion of OMW and LPM. PMID:25682225

  15. Jet observables without jet algorithms

    NASA Astrophysics Data System (ADS)

    Bertolini, Daniele; Chan, Tucker; Thaler, Jesse

    2014-04-01

    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 like a jet clustering algorithm, they incorporate a jet radius parameter and a transverse momentum cut. Three of the ubiquitous jet-based observables — jet multiplicity, summed scalar transverse momentum, and missing transverse momentum — have event shape counterparts that are closely correlated with their jet-based cousins. Due to their "local" computational structure, these jet-like event shapes could potentially be used for trigger-level event selection at the LHC. Intriguingly, the jet multiplicity event shape typically takes on non-integer values, highlighting the inherent ambiguity in defining jets. By inverting jet multiplicity, we show how to characterize the transverse momentum of the n-th hardest jet without actually finding the constituents of that jet. Since many physics applications do require knowledge about the jet constituents, we also build a hybrid event shape that incorporates (local) jet clustering information. As a straightforward application of our general technique, we derive an event-shape version of jet trimming, allowing event-wide jet grooming without explicit jet identification. Finally, we briefly mention possible applications of our method for jet substructure studies.

  16. Absolute instability of a viscous hollow jet

    Microsoft Academic Search

    Alfonso M. Gañán-Calvo

    2007-01-01

    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.

  17. Vortex diode jet

    DOEpatents

    Houck, Edward D. (Idaho Falls, ID)

    1994-01-01

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

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

    PubMed

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

    2012-10-22

    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

  19. Experimental study of pitching and plunging airfoils at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Baik, Yeon Sik; Bernal, Luis P.

    2012-12-01

    Measurements of the unsteady flow structure and force time history of pitching and plunging SD7003 and flat plate airfoils at low Reynolds numbers are presented. The airfoils were pitched and plunged in the effective angle of attack range of 2.4°-13.6° (shallow-stall kinematics) and -6° to 22° (deep-stall kinematics). The shallow-stall kinematics results for the SD7003 airfoil show attached flow and laminar-to-turbulent transition at low effective angle of attack during the down stroke motion, while the flat plate model exhibits leading edge separation. Strong Re-number effects were found for the SD7003 airfoil which produced approximately 25 % increase in the peak lift coefficient at Re = 10,000 compared to higher Re flows. The flat plate airfoil showed reduced Re effects due to leading edge separation at the sharper leading edge, and the measured peak lift coefficient was higher than that predicted by unsteady potential flow theory. The deep-stall kinematics resulted in leading edge separation that led to formation of a large leading edge vortex (LEV) and a small trailing edge vortex (TEV) for both airfoils. The measured peak lift coefficient was significantly higher (~50 %) than that for the shallow-stall kinematics. The effect of airfoil shape on lift force was greater than the Re effect. Turbulence statistics were measured as a function of phase using ensemble averages. The results show anisotropic turbulence for the LEV and isotropic turbulence for the TEV. Comparison of unsteady potential flow theory with the experimental data showed better agreement by using the quasi-steady approximation, or setting C( k) = 1 in Theodorsen theory, for leading edge-separated flows.

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

    PubMed

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

    2014-12-01

    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. PMID:25615081

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    Microsoft Academic Search

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

    2008-01-01

    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

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

    E-print Network

    McDonald, Kirk

    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

  4. 2003 Francois Frankiel Award: Experimental study of gravity-driven dense suspension jets

    Microsoft Academic Search

    Maxime Nicolas

    2003-01-01

    We present experimental results about a jet of dense suspension falling under gravity in a quiescent liquid bath of miscible liquid. The initial jet velocity v0 scales with the square of the initial jet diameter. Four different flow behaviors are observed. The jet remains cylindrical and stable when viscous forces are dominant. A capillary-like instability with formation of blobs occurs

  5. Mechanical probing of liquid foam aging

    E-print Network

    Isabelle Cantat; Olivier Pitois

    2006-09-19

    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.

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

    NASA Technical Reports Server (NTRS)

    Bennett, Robert M.

    2000-01-01

    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.

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

    SciTech Connect

    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

    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

  8. Axial jet mixing of ethanol in cylindrical containers during weightlessness

    NASA Technical Reports Server (NTRS)

    Aydelott, J. C.

    1979-01-01

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

  9. Axial jet mixing of ethanol in spherical containers during weightlessness

    NASA Technical Reports Server (NTRS)

    Audelott, J. C.

    1976-01-01

    An experimental program was conducted to examine the liquid flow patterns that result from the axial jet mixing of ethanol in 10-centimeter-diameter spherical containers in weightlessness. Complete liquid circulation flow patterns were easily established in containers that were less than half full of liquid, while for higher liquid fill conditions, vapor was drawn into the inlet of the simulated mixer unit. Increasing the liquid-jet or lowering the position at which the liquid jet entered the container caused increasing turbulence and bubble formation.

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

    PubMed

    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

    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

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

    Microsoft Academic Search

    David Rival; Dirk Schönweitz; Cameron Tropea

    2011-01-01

    The force evolution and associated vortex dynamics on a nominal two-dimensional tandem pitching and plunging configuration inspired by hovering dragonfly-like flight have been investigated experimentally using time-resolved particle image velocimetry. The aerodynamic forces acting on the flat plates have been determined using a classic control-volume approach, i.e. a momentum balance. It was found that only the tandem phasing of psi

  12. Liquid sampling system

    DOEpatents

    Larson, L.L.

    1984-09-17

    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.

  13. Liquid sampling system

    DOEpatents

    Larson, Loren L. (Idaho Falls, ID)

    1987-01-01

    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.

  14. Jet impact on a soap film

    E-print Network

    Kirstetter, Geoffroy; Celestini, Franck

    2012-01-01

    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.

  15. Jet impact on a soap film

    E-print Network

    Geoffroy Kirstetter; Christophe Raufaste; Franck Celestini

    2012-08-17

    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.

  16. Jet impact on a soap film

    NASA Astrophysics Data System (ADS)

    Kirstetter, Geoffroy; Raufaste, Christophe; Celestini, Franck

    2012-09-01

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

  17. Water Jetting

    NASA Technical Reports Server (NTRS)

    1985-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Lutze, Frederick H.; Fan, Yigang

    1999-01-01

    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.

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

    E-print Network

    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

    (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.

  20. A novel needleless liquid jet injection methodology for improving direct cardiac gene delivery: An optimization of parameters, AAV mediated therapy and investigation of host responses in ischemic heart failure

    NASA Astrophysics Data System (ADS)

    Fargnoli, Anthony Samuel

    Heart disease remains the leading cause of mortality and morbidity worldwide, with 22 million new patients diagnosed annually. Essentially, all present therapies have significant cost burden to the healthcare system, yet fail to increase survival rates. One key employed strategy is the genetic reprogramming of cells to increase contractility via gene therapy, which has advanced to Phase IIb Clinical Trials for advanced heart failure patients. It has been argued that the most significant barrier preventing FDA approval are resolving problems with safe, efficient myocardial delivery, whereby direct injection in the infarct and remote tissue areas is not clinically feasible. Here, we aim to: (1) Improve direct cardiac gene delivery through the development of a novel liquid jet device approach (2) Compare the new method against traditional IM injection with two different vector constructions and evaluate outcome (3) Evaluate the host response resulting from both modes of direct cardiac injection, then advance a drug/gene combination with controlled release nanoparticle formulations.

  1. Compound class quantitation of JP-5 jet fuels by high performance liquid chromatography\\/differential refractive index detection. Memorandum report June 1982June 1983

    Microsoft Academic Search

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

    1984-01-01

    Fuel composition effects are known to significantly affect jet turbine engine performance. Currently, one important composition parameter, total aromatics (% v\\/v), is actually defined in all JP-4 and JP-5 military fuel specifications governing procurement. This report outlines an improved method for defining not only total aromatics but also the two sub-classes, mono-cyclic and di-cyclic aromatics, that make up the total

  2. 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)

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

    2008-10-01

    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.

  3. Laser-induced break-up of water jet waveguide

    Microsoft Academic Search

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

    2004-01-01

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

  4. [Jet leg].

    PubMed

    Christiansen, A L; Madsbad, S

    2001-01-01

    The aim of the paper is to give a review of jet-lag (Time Zone Change Syndrome) with regard to aetiology, symptomatology and pathophysiology. Furthermore we give recommendations on treatment of jet-lag. The literature has focused intensely on the potential benefit of phototherapy and/or use of melatonin as treatment modalities for jet-lag. Both phototherapy and melatonin have the capability to accelerate reentrainment of the circadian rhythm after flights across multiple time zones, thereby reducing jet-lag. We stress the importance of correct timing of phototherapy and use of melatonin and suggest that the traveller adapts to the "social" rhythm at the flight destination as well. PMID:11379239

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  6. Experimental study on flow kinematics and impact pressure in liquid sloshing

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

  7. Emerging Jets

    E-print Network

    Pedro Schwaller; Daniel Stolarski; Andreas Weiler

    2015-02-24

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilities for discovery at LHCb are also discussed.

  8. Emerging Jets

    E-print Network

    Schwaller, Pedro; Weiler, Andreas

    2015-01-01

    In this work, we propose a novel search strategy for new physics at the LHC that utilizes calorimeter jets that (i) are composed dominantly of displaced tracks and (ii) have many different vertices within the jet cone. Such emerging jet signatures are smoking guns for models with a composite dark sector where a parton shower in the dark sector is followed by displaced decays of dark pions back to SM jets. No current LHC searches are sensitive to this type of phenomenology. We perform a detailed simulation for a benchmark signal with two regular and two emerging jets, and present and implement strategies to suppress QCD backgrounds by up to six orders of magnitude. At the 14 TeV LHC, this signature can be probed with mediator masses as large as 1.5 TeV for a range of dark pion lifetimes, and the reach is increased further at the high-luminosity LHC. The emerging jet search is also sensitive to a broad class of long-lived phenomena, and we show this for a supersymmetric model with R-parity violation. Possibilit...

  9. Absolute instability of a viscous hollow jet

    NASA Astrophysics Data System (ADS)

    Gañán-Calvo, Alfonso M.

    2007-02-01

    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.

  10. Absolute instability of a viscous hollow jet.

    PubMed

    Gañán-Calvo, Alfonso M

    2007-02-01

    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

  11. Jet formation from impulsive cavity collapse

    Microsoft Academic Search

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

    2006-01-01

    A cavity at a free liquid\\/gas interface collapsing due to an impulsive body force forms an intense concentrated jet. This is the paradigm for bubbles bursting at a liquid surface, the collapse of cavitation bubbles near a rigid boundary, collapsing voids following an impact, shaped charges, gravity waves colliding a dam, high amplitude Faraday waves, to quote a few examples

  12. Production of cell-enclosing hollow-core agarose microcapsules via jetting in water-immiscible liquid paraffin and formation of embryoid body-like spherical tissues from mouse ES cells enclosed within these microcapsules.

    PubMed

    Sakai, Shinji; Hashimoto, Ichiro; Kawakami, Koei

    2008-01-01

    We developed agarose microcapsules with a single hollow core templated by alginate microparticles using a jet-technique. We extruded an agarose aqueous solution containing suspended alginate microparticles into a coflowing stream of liquid paraffin and controlled the diameter of the agarose microparticles by changing the flow rate of the liquid paraffin. Subsequent degradation of the inner alginate microparticles using alginate lyase resulted in the hollow-core structure. We successfully obtained agarose microcapsules with 20-50 microm of agarose gel layer thickness and hollow cores ranging in diameter from ca. 50 to 450 microm. Using alginate microparticles of ca. 150 microm in diameter and enclosing feline kidney cells, we were able to create cell-enclosing agarose microcapsules with a hollow core of ca. 150 microm in diameter. The cells in these microcapsules grew much faster than those in alginate microparticles. In addition, we enclosed mouse embryonic stem cells in agarose microcapsules. The embryonic stem cells began to self-aggregate in the core just after encapsulation, and subsequently grew and formed embryoid body-like spherical tissues in the hollow core of the microcapsules. These results show that our novel microcapsule production technique and the resultant microcapsules have potential for tissue engineering, cell therapy and biopharmaceutical applications. PMID:17705234

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

    SciTech Connect

    Mansour, A.; Chigier, N.

    1993-12-31

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

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

    PubMed

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

    2010-01-01

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

  15. Experimental study of elliptical jet from sub to supercritical conditions

    SciTech Connect

    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

    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.

  16. Helium jet dispersion to atmosphere

    NASA Technical Reports Server (NTRS)

    Khan, Hasna J.

    1986-01-01

    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.

  17. Numerical Simulations of Bouncing Jets

    E-print Network

    Bonito, Andrea; Lee, Sanghyun

    2015-01-01

    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.

  18. Liquid surface breakup of nonturbulent and turbulent liquids

    Microsoft Academic Search

    Pei-Kuan Wu

    1992-01-01

    An experimental study of the primary breakup in the near-injector region of large diameter (3.6-9.5 mm) liquid jets in still gases is described. The experiments involve the injection of different test liquids at a variety of velocities into various gas environments, with slug flow and fully-developed turbulent pipe flow at the jet exit. Measurements included flash photography, pulsed shadowgraphy, and

  19. Influence of heat transfer on the aerodynamic performance of a plunging and pitching NACA0012 airfoil at low Reynolds numbers

    NASA Astrophysics Data System (ADS)

    Hinz, Denis F.; Alighanbari, Hekmat; Breitsamter, Christian

    2013-02-01

    The unsteady low Reynolds number aerodynamics phenomena around flapping wings are addressed in several investigations. Elsewhere, airfoils at higher Mach numbers and Reynolds numbers have been treated quite comprehensively in the literature. It is duly noted that the influence of heat transfer phenomena on the aerodynamic performance of flapping wings configurations is not well studied. The objective of the present study is to investigate the effect of heat transfer upon the aerodynamic performance of a pitching and plunging NACA0012 airfoil in the low Reynolds number flow regime with particular emphasis upon the airfoil's lift and drag coefficients. The compressible Navier-Stokes equations are solved using a finite volume method. To consider the variation of fluid properties with temperature, the values of dynamic viscosity and thermal diffusivity are evaluated with Sutherland's formula and the Eucken model, respectively. Instantaneous and mean lift and drag coefficients are calculated for several temperature differences between the airfoil surface and freestream within the range 0-100 K. Simulations are performed for a prescribed airfoil motion schedule and flow parameters. It is learnt that the aerodynamic performance in terms of the lift CL and drag CD behavior is strongly dependent upon the heat transfer rate from the airfoil to the flow field. In the plunging case, the mean value of CD tends to increase, whereas the amplitude of CL tends to decrease with increasing temperature difference. In the pitching case, on the other hand, the mean value and the amplitude of both CD and CL decrease. A spectral analysis of CD and CL in the pitching case shows that the amplitudes of both CD and CL decrease with increasing surface temperature, whereas the harmonic frequencies are not affected.

  20. Gas Jets

    NASA Technical Reports Server (NTRS)

    Chaplygin, S.

    1944-01-01

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

  1. Shock-Wave-Induced Jetting of Micron-Size Bubbles

    NASA Astrophysics Data System (ADS)

    Ohl, C. D.; Ikink, R.

    2003-05-01

    Free gas bubbles in water with radii between 7 and 55 ?m subjected to a shock wave exhibit a liquid jetting phenomenon with the jet pointing in the direction of the propagating shock wave. With increasing bubble radius, the length of the jet tip increases and a lower estimate of the averaged jet velocity increases linearly from 20 to 150 m/s. At a later stage, the jet breaks up and releases micron-size bubbles. In the course of shock wave permeabilization and transfection of biological cells, this observation suggests a microinjection mechanism when the cells are near bubbles exposed to a shock wave.

  2. AEA Fluidic Pulse Jet Mixer. Innovative Technology Summary Report

    SciTech Connect

    None

    1999-08-01

    AEA's Fluidic Pulse Jet Mixer was developed to mix and maintain the suspension of solids and to blend process liquids. The mixer can be used to combine a tank's available supernate with the sludge into a slurry that is suitable for pumping. The system uses jet nozzles in the tank coupled to a charge vessel. Then, a jet pump creates a partial vacuum in the charge vessel allowing it to be filled with waste. Next, air pressure is applied to the charge vessel, forcing sludge back into the tank and mixing it with the liquid waste. When the liquid waste contains 10% solids, a batch is pumped out of the tank.

  3. Electrohydrodynamic (EHD) stimulation of jet breakup

    NASA Technical Reports Server (NTRS)

    Crowley, J. M.

    1982-01-01

    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.

  4. Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  5. DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

    SciTech Connect

    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

    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.

  6. Marine Jet

    NASA Technical Reports Server (NTRS)

    1978-01-01

    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.

  7. Jets from compact objects

    E-print Network

    H. C. Spruit

    2000-03-03

    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.

  8. 2D Jet Simulation Updates Jan.23rd 2014

    E-print Network

    McDonald, Kirk

    /VOF/ghost fluid methods: Validation and application to 3D simulation of the primary breakup of a liquid jet) : Next: Turn to Unsteady Simulation #12;More Information 19 [2] PK Wu and G M Faeth, Onset and end

  9. Slender jets and thin sheets with surface tension

    Microsoft Academic Search

    Ting Lu; Joseph B. Keller

    1990-01-01

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

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

    PubMed

    Rival, David; Schönweitz, Dirk; Tropea, Cameron

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  12. 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)

    Dcruz, Jonathan

    1993-01-01

    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.

  13. Jet energy scale determination in the D0 experiment

    NASA Astrophysics Data System (ADS)

    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

    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.

  14. Inclusive Jets in PHP

    NASA Astrophysics Data System (ADS)

    Roloff, P.

    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.

  15. Jet radiation radius

    NASA Astrophysics Data System (ADS)

    Han, Zhenyu

    2014-10-01

    Jet radiation patterns are indispensable for the purpose of discriminating partons with different quantum numbers. However, they are also vulnerable to various contaminations from the underlying event, pileup, and radiation of adjacent jets. In order to maximize the discrimination power, it is essential to optimize the jet radius used when analyzing the radiation patterns. We introduce the concept of jet radiation radius, which quantifies how the jet radiation is distributed around the jet axis. We study the color and momentum dependence of the jet radiation radius and discuss two applications: quark-gluon discrimination and W -jet tagging. In both cases, smaller (sub)jet radii are preferred for jets with higher pT's, albeit due to different mechanisms: the running of the QCD coupling constant and the boost to a color-singlet system. A shrinking cone W -jet tagging algorithm is proposed to achieve better discrimination than previous methods.

  16. Oscillatory system of the jet electromagnetic vibrator

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  17. Jet inclusive cross sections

    SciTech Connect

    Del Duca, V.

    1992-11-01

    Minijet production in jet inclusive cross sections at hadron colliders, with large rapidity intervals between the tagged jets, is evaluated by using the BFKL pomeron. We describe the jet inclusive cross section for an arbitrary number of tagged jets, and show that it behaves like a system of coupled pomerons.

  18. Jet Physics at Tevatron

    SciTech Connect

    G. Latino

    2003-12-15

    An overview of Run I jet physics at the p{bar p} Fermilab Tevatron Collider with a particular emphasis on inclusive jet cross section measurements is given. The impact of these studies on PDFs constrain from global fits is underlined. Preliminary results on inclusive jet and di-jet mass cross section measurements in Run II are then summarized.

  19. Liquid Wall Chambers

    SciTech Connect

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

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

    SciTech Connect

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

    2001-06-18

    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.

  1. General review of flashing jet studies.

    PubMed

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

    2010-01-15

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

  2. Jet fuels from synthetic crudes

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

    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.

  3. Project HyBuJET

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    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.

  4. Mixing liquids in microseconds

    NASA Astrophysics Data System (ADS)

    Regenfuss, Peter; Clegg, Robert M.; Fulwyler, Mack. J.; Barrantes, Francisco J.; Jovin, Thomas M.

    1985-02-01

    An instrument is described in which two solutions can be homogeneously mixed within several microseconds. The liquids flow separately through two coaxial capillaries with conical tips and then simultaneously around a sphere (50-100 ? in diameter) which has been positioned close to the end of the outer tip. The liquids flow with velocities of ˜100 m/s through the small passages (˜5 ? wide) separating the sphere and the wall of the outer capillary and mix in the turbulent liquid flow behind the sphere. The mixed liquids are then ejected as a narrow liquid jet for observation. Design characteristics and construction techniques are presented along with a discussion of the properties of the turbulent flow field and estimates of the expected practically realizable mixing times. The experimentally determined speed of mixing indicates that we have nearly achieved the proposed lower limits of the mixing time.

  5. IFE THICK LIQUID WALL CHAMBER DYNAMICS: GOVERNING MECHANISMS AND MODELING AND

    E-print Network

    Raffray, A. René

    , and possible aerosol formation, as well as protective jet behavior. This paper focuses on these research topics, single and seg- mented annular curtains, and various combinations of rectangular and cylindrical liquid jets to make up the main

  6. Jet Boost Pumps For The Space Shuttle Main Engine

    NASA Technical Reports Server (NTRS)

    Meng, Sen Y.

    1991-01-01

    Brief report proposes use of jet boost pumps in conjunction with main pumps supplying liquid hydrogen and liquid oxygen to main engine of Space Shuttle. Main part of pump has no moving parts. Benefits include increased reliability, simplified ducts, and decreased weight.

  7. Hydrodynamic and hydromagnetic stability of a finite hollow jet

    Microsoft Academic Search

    Samia S. Elazab

    1990-01-01

    The hydrodynamic and hydromagnetic stability of a gas jet coaxial with a liquid cylinder (with solid cylindrical edge) acted upon the capillary, electromagnetic and inertia liquid forces is presented. A general eigenvalue relation is derived and verified, using the conservation energy principle. The analytical stability results are confirmed numerically and interpreted physically. The surface tension is destabilizing only in the

  8. Observation of Birefringence of an Electrospinning Jet in Flight

    NASA Astrophysics Data System (ADS)

    Liu, Kaiyi; Reneker, Darrell

    2013-03-01

    Solutions of polystyrene in N,N-dimethylformamide, polyacrylonitrile in N,N-dimethylformamide, and polyethylene oxide in water were electrospun. The charged liquid jets in flight were illuminated with polarized light converged on the jets by a Fresnel lens with a black background at the center, and were observed using a high speed camera, coaxial with the Fresnel lens, behind an analyzer which was crossed with a polarizer in front of the light source. The first several turns of coiled jet after the onset of electrical bending instability showed birefringence for all solutions, while no obvious birefringence was observed in the straight segments of the jets. This indicated that molecular chains in the coiled jet were aligned under elongation to a higher extent than those in the thicker straight jet.

  9. Risk factors of jet fuel combustion products.

    PubMed

    Tesseraux, Irene

    2004-04-01

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

  10. Subrelativistic Jet Heating Mechanisms

    NASA Astrophysics Data System (ADS)

    Bisnovatyi-Kogan, G. S.; Krivosheyev, Y. M.

    Different physical processes, influencing the X-ray jet's thermal balance are considered. We focus on the problem of possible fast jet cooling via radiative losses. Thus, the contributions of each process to the jet thermal balance are calculated. We investigate the influence of shock wave propagation on jet heating, and the mechanism of jet kinetic energy transformation into heat via Coulomb collisions of jet and corona protons. Quantitative estimates are made for the case of Galactic microquasar SS433 based on previous results of the authors. The only important heating mechanism for this source turned out to be Coulomb collisions.

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

    Microsoft Academic Search

    D. C. Wadsworth; I. Mudawar

    1992-01-01

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

  12. Control of jet noise

    NASA Technical Reports Server (NTRS)

    Schreck, Stefan

    1993-01-01

    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.

  13. The Middle School Plunge

    ERIC Educational Resources Information Center

    West, Martin; Schwerdt, Guido

    2012-01-01

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

  14. Vietnam plunges ahead

    SciTech Connect

    Burr, M.T.

    1995-07-01

    Vietnam is moving fast. Facing the need to double its installed power generation capacity by the year 2000, Vietnam is pursuing a range of development alternatives to add an estimated 3,000 MW of new power plants. As part of the country`s progress toward a market economy, Vietnam has relaxed its rules regarding investment in power plants. The country enacted a new electricity law early in 1995, paving the way for private participation in the power sector.

  15. Theory of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Vlahakis, Nektarios

    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.

  16. Jet physics in ALICE

    Microsoft Academic Search

    Constantinos A. Loizides; Johann Wolfgang von Goethe

    2005-01-01

    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

  17. Vapor-liquid contacting system

    SciTech Connect

    Butwell, K.F.; Sigmund, P.W.

    1981-10-27

    A vapor-liquid contacting tray is described wherein a perforated portion of the tray member forms an active surface area for vapor-liquid contact in the interior of the tray member. The active surface area portion of the tray member is circumscribed by an imperforate peripheral portion of the tray member with a width of from 0.05 to 0.35 times the radius of the tray. The disclosed tray provides upwardly directed laminar jetting of liquid over the tray perforation openings for high selectivity vapor-liquid contacting and has particular utility in the absorption of hydrogen sulfide from a gas mixture containing hydrogen sulfide and carbon dioxide.

  18. Prewhirl Jet Model

    NASA Technical Reports Server (NTRS)

    Meng, S. Y.; Jensen, M.; Jackson, E. D.

    1985-01-01

    Simple accurate model of centrifugal or rocket engine pumps provides information necessary to design inducer backflow deflector, backflow eliminator and prewhirl jet in jet mixing zones. Jet design based on this model shows improvement in inducer suction performance and reduced cavitation damage.

  19. Jet Substructure Without Trees

    E-print Network

    Martin Jankowiak; Andrew J. Larkoski

    2011-06-30

    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.

  20. Diffusion of pipe jets

    Microsoft Academic Search

    S. K. Al-Naib; R. Vasanthakumaran

    1993-01-01

    This paper presents fundamental research work on jet dissipation in pipes and closed chambers in order to study the details of flow pattern, velocity distribution, and energy reduction. The effects of chamber dimensions and jet heights are also investigated. Experiments were carried out with air and water jets being discharged into a pipe. The ratio of pipe to nozzle diameter

  1. Fluid jet electric discharge source

    DOEpatents

    Bender, Howard A. (Ripon, CA)

    2006-04-25

    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.

  2. Contact Angle Influence on Geysering Jets in Microgravity Investigated

    NASA Technical Reports Server (NTRS)

    Chato, David J.

    2004-01-01

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

  3. Manipulating Liquids with Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    1997-01-01

    At the NASA Lewis Research Center, high-intensity ultrasound is being used to create acoustic radiation pressure (ARP) on objects in liquids. It is also being used to create liquid currents or jets called acoustic streaming. NASA's interest in ARP includes remote-control agitation of liquid systems in space, such as in liquid space experiments and liquid propellant tanks. It can be used to eject or deploy droplets for droplet physics or droplet combustion experiments. It can also be used to manipulate bubbles, drops, and surfaces suspended in liquid experiments and propellant systems.

  4. Experimental study on drop formation in liquid–liquid fluidized bed

    Microsoft Academic Search

    Zhengbiao Peng; Zhulin Yuan; Xuan Wu; Jie Cai; Fengxian Fan; Li Tie; Geng Fan; Chen Pan; Kunfeng Liang

    2009-01-01

    Drop formation in liquid–liquid fluidized bed was investigated experimentally. The normal water was injected via a fine-capillary spray nozzle into the co-flowing No. 25 transformer oil with jet directed upwards in a vertical fluidized bed. Experiments under a wide variety of conditions were conducted to investigate the instability dynamics of the jet, the size and size distribution of the drops.

  5. Rocket engine versus jet engine comparison

    NASA Astrophysics Data System (ADS)

    Meisl, Claus J.

    1992-07-01

    Results of a comparative investigation are presented which analyzed the commonalities and differences of liquid propellant booster rocket engines and airbreathing engines for military, high performance aircraft. The investigation covered: (1) physical environment and design requirements, (2) production costs, (3) reliability parameters, (4) maintenance characteristics and (5) the relationship of ownership and life cycle costs. Results showed that in spite of the large differences in internal physical environment and design requirements, production costs of jet engines and gas generator cycle rocket engines are similar when compared at the same engine weight and production quantity. Reliabilities of the two different engine types are similar when compared on a per mission basis. The relationship between ownership and acquisition costs is almost identical. Maintenance and overhaul costs for jet engines are much lower than those for rocket engines, due to the much higher mission rates and the more benign internal environment of jet engines.

  6. Cavitating vortex generation by a submerged jet

    SciTech Connect

    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

    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.

  7. Jet pump assisted arterial heat pipe

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    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.

  8. Computer modeling of jet mixing in INEL waste tanks

    SciTech Connect

    Meyer, P.A.

    1994-01-01

    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.

  9. Liquid-Liquid Extraction Processes

    E-print Network

    Fair, J. R.; Humphrey, J. L.

    1983-01-01

    Liquid-liquid extraction is the separation of one or more components of a liquid solution by contact with a second immiscible liquid called the solvent. If the components in the original liquid solution distribute themselves differently between...

  10. Refrigerated hydrogen gas jet for the Fermilab antiproton accumulator

    SciTech Connect

    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

    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.

  11. Jet Substructure Without Trees

    SciTech Connect

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

    2011-08-19

    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.

  12. What ignites optical jets?

    E-print Network

    S. Jester

    2003-01-08

    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.

  13. Jet Propagation and Deceleration

    NASA Astrophysics Data System (ADS)

    Perucho, Manel

    2014-03-01

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

  14. Stability of Astrophysical Jets

    NASA Astrophysics Data System (ADS)

    Komissarov, Serguei

    2014-08-01

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

  15. Interpretation of extragalactic jets

    SciTech Connect

    Norman, M.L.

    1985-01-01

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

  16. The jet in crossflowa)

    NASA Astrophysics Data System (ADS)

    Karagozian, Ann R.

    2014-10-01

    The jet in crossflow, or transverse jet, is a flowfield that has relevance to a wide range of energy and propulsion systems. Over the years, our group's studies on this canonical flowfield have focused on the dynamics of the vorticity associated with equidensity and variable density jets in crossflow, including the stability characteristics of the jet's upstream shear layer, as a means of explaining jet response to altered types of excitation. The jet's upstream shear layer is demonstrated to exhibit convectively unstable behavior at high jet-to-crossflow momentum flux ratios, transitioning to absolutely unstable behavior at low momentum flux and/or density ratios, with attendant differences in shear layer vorticity evolution and rollup. These differences in stability characteristics are shown to have a significant effect on how one optimally employs external excitation to control jet penetration and spread, depending on the flow regime and specific engineering application. Yet recent unexpected observations on altered transverse jet structure under different flow conditions introduce a host of unanswered questions, primarily but not exclusively associated with the nature of molecular mixing, that make this canonical flowfield one that is of great interest for more extensive exploration.

  17. Baroclinic splitting of jets

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

    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.

  18. Cryo-electron tomography of plunge-frozen whole bacteria and vitreous sections to analyze the recently described bacterial cytoplasmic structure, the Stack.

    PubMed

    Delgado, Lidia; Martínez, Gema; López-Iglesias, Carmen; Mercadé, Elena

    2015-03-01

    Cryo-electron tomography (CET) of plunge-frozen whole bacteria and vitreous sections (CETOVIS) were used to revise and expand the structural knowledge of the "Stack", a recently described cytoplasmic structure in the Antarctic bacterium Pseudomonas deceptionensis M1(T). The advantages of both techniques can be complementarily combined to obtain more reliable insights into cells and their components with three-dimensional imaging at different resolutions. Cryo-electron microscopy (Cryo-EM) and CET of frozen-hydrated P. deceptionensis M1(T) cells confirmed that Stacks are found at different locations within the cell cytoplasm, in variable number, separately or grouped together, very close to the plasma membrane (PM) and oriented at different angles (from 35° to 90°) to the PM, thus establishing that they were not artifacts of the previous sample preparation methods. CET of plunge-frozen whole bacteria and vitreous sections verified that each Stack consisted of a pile of oval disc-like subunits, each disc being surrounded by a lipid bilayer membrane and separated from each other by a constant distance with a mean value of 5.2±1.3nm. FM4-64 staining and confocal microscopy corroborated the lipid nature of the membrane of the Stacked discs. Stacks did not appear to be invaginations of the PM because no continuity between both membranes was visible when whole bacteria were analyzed. We are still far from deciphering the function of these new structures, but a first experimental attempt links the Stacks with a given phase of the cell replication process. PMID:25617813

  19. Rectangular jets in a crossflow

    NASA Technical Reports Server (NTRS)

    Kavsaoglu, M. S.; Schetz, J. A.; Jakubowski, A. K.

    1989-01-01

    Rectangular jets injected from a flat plate into a crossflow at large angles have been studied. Results were obtained as surface pressure distributions, mean velocity vector plots, turbulence intensities, and Reynolds stresses in the jet plume. The length-to-width ratio of the jets was 4, and the jets were aligned streamwise as single and side-by-side dual jets. The jet injection angles were 90 and 60 deg. Surface pressure distribution results were obtained for jet-to-freestream velocity ratios of 2.2, 4, and 8. Mean flow and turbulence flowfield data were obtained for the side-by-side dual jets, mainly for the jet-to-freestream velocity ratio of 4. The jets featured strong negative pressure peaks near the front nozzle corners. The 60-deg jets produced lower magnitude negative pressures, which are distributed over a lesser area when compared to the 90-deg jets.

  20. Rectangular jets in a crossflow

    Microsoft Academic Search

    M. S. Kavsaoglu; J. A. Schetz; A. K. Jakubowski

    1989-01-01

    Rectangular jets injected from a flat plate into a crossflow at large angles have been studied. Results were obtained as surface pressure distributions, mean velocity vector plots, turbulence intensities, and Reynolds stresses in the jet plume. The length-to-width ratio of the jets was 4, and the jets were aligned streamwise as single and side-by-side dual jets. The jet injection angles

  1. Instabilities of jets of non-Newtonian fluids impacting a plate

    E-print Network

    Varagnat, Matthieu

    2008-01-01

    The problem of buckling and coiling of jets of viscous, Newtonian liquids impacting a plate has received a substantial level of attention over the past two decades, both from experimental and theoretical points of view. ...

  2. FastJet user manual

    E-print Network

    Matteo Cacciari; Gavin P. Salam; Gregory Soyez

    2011-11-25

    FastJet is a C++ package that provides a broad range of jet finding and analysis tools. It includes efficient native implementations of all widely used 2-to-1 sequential recombination jet algorithms for pp and e+e- collisions, as well as access to 3rd party jet algorithms through a plugin mechanism, including all currently used cone algorithms. FastJet also provides means to facilitate the manipulation of jet substructure, including some common boosted heavy-object taggers, as well as tools for estimation of pileup and underlying-event noise levels, determination of jet areas and subtraction or suppression of noise in jets.

  3. Jet lag prevention

    MedlinePLUS

    Jet lag is a sleep disorder that occurs when the body's biological clock does not correspond to local ... Here are some tips to help prevent jet lag: Maintain a sensible ... in order to make yourself tired. Consider going to bed earlier ...

  4. JET ENGINE CERTIFICATION STANDARDS

    Microsoft Academic Search

    Paul Eschenfelder

    2000-01-01

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

  5. Jet Streak Circulations

    NSDL National Science Digital Library

    2014-09-14

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

  6. Jet Streams and Weather

    NSDL National Science Digital Library

    2005-01-01

    In this lesson, students learn about jet streams and explore the effects the polar-front jet stream has on weather conditions in North America. They begin by doing an interactive activity that highlights the atmospheric conditions and phenomena that create jet streams. They then look at a model that illustrates the relationships between latitude and variations in air temperature, wind speed, and altitude and begin to make generalizations about these relationships. In the second part of this lesson, they use the knowledge gained in the first part to interpret weather maps, helping them to make direct connections between the behavior of the polar-front jet stream and seasonal weather patterns in North America. As a final exercise, they will use real data to deepen their understanding of the relationships between pressure, altitude, and the wind speed of jet streams.

  7. Description of Jet Breakup

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.

    1996-01-01

    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.

  8. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  9. Multiple jet study

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  10. A HIGH-FIELD PULSED SOLENOID MAGNET FOR LIQUID METAL TARGET STUDIES

    E-print Network

    McDonald, Kirk

    this device at the Brookhaven AGS for proof-of-principle testing of a liquid-jet target system with pulses studies have been car- ried out for rotating-band targets, a tantalum/water target, and a liquid, the operation of rf cavities near high-power targets, and evaluation of target materials. Mercury Jet + Proton

  11. Near-field Structure of Dilute, Dispersed Bubbly Jets

    NASA Astrophysics Data System (ADS)

    Stanley, Kevin N.; Guerry, Stephanie; Nikitopoulos, Dimitris E.

    1999-11-01

    Results of experiments conducted in the developing region of a free, axisymmetric, isothermal, air-water, bubbly jet will be presented. Experiments have been conducted at three different values of jet-exit Reynolds number (6,000; 12,000; and 18,000) at various volumetric flow ratios within the range of 0.3-3.0%. Bubble-size and two components of bubble and liquid velocity have been measured non-intrusively using light-scattering and imaging techniques. Visualizations of the bubble motion have also been carried out. The measurements show that differences in bubble-size, size distribution, and phase distribution influence the mean flow evolution, the fluctuation intensity of the carrier liquid phase, bubble relative velocities, and the RMS velocity fluctuations of the bubbles in the jet development region. These observations have been correlated to the size, concentration, relative velocity and RMS velocity fluctuations of the bubbles. Bubble frequency profiles indicate that bubble migration both radially inwards and outwards occurs in the developing region of the jet. Bubble relative velocities are shown to deviate considerably from those predicted by steady- or quasisteady- state correlations. The measurements supplemented by visualization observations suggest that the unsteady interactions between bubbles and liquid phase large-scale structures strongly influence bubble motion, shape and phase distribution in the developing region of the jet.

  12. An Overview of the Fluid Dynamics Aspects of Liquid Protection

    E-print Network

    California at San Diego, University of

    chamber first walls from neutrons, X-rays and charged particles. Oscillating slabs Cylindrical jets Beam Source Term" · Used simple mass collection system to measure mass flux of liquid droplets ejected from Density (x / = 25) · Droplet mass flux values for jets produced by nozzles with optimized flow

  13. Thrust vector control by liquid injection for solid propellant rockets

    NASA Technical Reports Server (NTRS)

    Zeamer, R. J.

    1975-01-01

    In liquid injection thrust vector control, a rocket jet is deflected for steering purposed by injecting a liquid into the nozzle exit cone. The liquid is preferably both dense and reactive so that it adds mass and energy and generates shocks in the supersonic exhaust. This behavior increases thrust in the affected part of the jet producing not only a side force for steering but an addition to axial thrust. This paper presents a summary of current liquid injection thrust vector control technology, including procedures for design, development, analysis, testing and evaluation, together with supporting data and references.

  14. Potential of liquid hydrogen as a military aircraft fuel

    Microsoft Academic Search

    W. T. Mikolowsky; L. W. Noggle

    1976-01-01

    Comparison of synthetic jet-fuel (syn-jet) and liquid hydrogen fuel indicates that the former is the better alternative fuel for very large airplanes. Liquid hydrogen is less cost- and energy-effective and, until coal reserves are depleted, would not be a satisfactory aircraft fuel. These conclusions are based on strategic airlift mission analysis and station-keeping analysis, with comparisons made for relative cost

  15. Integrated coke, asphalt and jet fuel production process and apparatus

    DOEpatents

    Shang, Jer Y. (McLean, VA)

    1991-01-01

    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.

  16. Integrated coke, asphalt and jet fuel production process and apparatus

    SciTech Connect

    Shang, J.Y.

    1991-04-16

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

  17. Angular Scaling In Jets

    SciTech Connect

    Jankowiak, Martin; Larkoski, Andrew J.; /SLAC

    2012-02-17

    We introduce a jet shape observable defined for an ensemble of jets in terms of two-particle angular correlations and a resolution parameter R. This quantity is infrared and collinear safe and can be interpreted as a scaling exponent for the angular distribution of mass inside the jet. For small R it is close to the value 2 as a consequence of the approximately scale invariant QCD dynamics. For large R it is sensitive to non-perturbative effects. We describe the use of this correlation function for tests of QCD, for studying underlying event and pile-up effects, and for tuning Monte Carlo event generators.

  18. ATLAS Jet Energy Scale

    E-print Network

    D. Schouten; A. Tanasijczuk; M. Vetterli; for the ATLAS Collaboration

    2012-01-11

    Jets originating from the fragmentation of quarks and gluons are the most common, and complicated, final state objects produced at hadron colliders. A precise knowledge of their energy calibration is therefore of great importance at experiments at the Large Hadron Collider at CERN, while is very difficult to ascertain. We present in-situ techniques and results for the jet energy scale at ATLAS using recent collision data. ATLAS has demonstrated an understanding of the necessary jet energy corrections to within \\approx 4% in the central region of the calorimeter.

  19. Rapidity Gaps Between Jets

    E-print Network

    J. M. Butterworth; M. E. Hayes; M. H. Seymour; L. E. Sinclair

    1996-09-02

    An excess of events with a rapidity gap between jets, over what would be expected from non-diffractive processes, has been observed at HERA. A process based on a perturbative QCD calculation of colour singlet exchange has been added to HERWIG. With this addition, HERWIG is able to describe the number of events with a gap between jets over the number without a gap. This gap fraction is predicted to rise at large rapidity intervals between jets which would only be visible if the detector coverage were increased.

  20. Oscillating acoustic streaming jet

    NASA Astrophysics Data System (ADS)

    Moudjed, Brahim; Botton, Valéry; Henry, Daniel; Millet, Séverine; Garandet, Jean-Paul; Ben-Hadid, Hamda

    2014-11-01

    The present paper provides the first experimental investigation of an oscillating acoustic streaming jet. The observations are performed in the far field of a 2 MHz circular plane ultrasound transducer introduced in a rectangular cavity filled with water. Measurements are made by Particle Image Velocimetry (PIV) in horizontal and vertical planes near the end of the cavity. Oscillations of the jet appear in this zone, for a sufficiently high Reynolds number, as an intermittent phenomenon on an otherwise straight jet fluctuating in intensity. The observed perturbation pattern is similar to that of former theoretical studies. This intermittently oscillatory behavior is the first step to the transition to turbulence.

  1. Nonstationary macroparticle charging in an arc plasma jet

    Microsoft Academic Search

    Michael Keidar; Isak I. Beilis; R. L. Boxman; Samuel Goldsmith

    1995-01-01

    The charging of liquid metal macroparticles in the rarified part of a vacuum arc plasma jet is studied. The sheath in the vicinity of the macroparticle is collisionless and the problem with different Debye length to macroparticle radius ratios is analyzed. Maxwellian velocity distribution functions with different temperatures for the electrons and ions in an arbitrary ratio are allowed in

  2. Numerical simulation of turbulent jet primary breakup in Diesel engines

    E-print Network

    Helluy, Philippe

    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

  3. The ways of mass transfer intensification in industrial jet scrubbers

    NASA Astrophysics Data System (ADS)

    Shilyaev, Michael; Khromova, Helen; Shirokova, Svetlana

    2015-01-01

    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).

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  5. Nonaxisymmetric Poynting Jets

    E-print Network

    Gralla, Samuel E

    2015-01-01

    The relativistic plasma jets from a misaligned black hole-accretion disk system will not be axially symmetric. Here we analyze nonaxisymmetric, stationary, translation invariant jets in the force-free approximation where the field energy dominates the particle energy. We derive a stream equation for these configurations involving the flux function $\\psi$ for the transverse magnetic field, the linear velocity $v(\\psi)$ of field lines along the jet, and the longitudinal magnetic field $B_z(\\psi)$. The equations can be completely solved when $|v|=1$, and when $|v|E^2$. Finally, we write down specific solutions approximating numerical results for the nonaxisymmetric jet produced by a spinning black hole in an external, misaligned magnetic field.

  6. Modelling jet quenching

    NASA Astrophysics Data System (ADS)

    Renk, Thorsten

    2013-08-01

    High PT measurements of hard hadrons or jets at RHIC and LHC appear contradictory and in some cases counterintuitive, but upon closer investigation they represent a coherent picture of jet-medium interaction physics which can be established with systematic comparisons of models against a large body of data. This picture is consistent with a perturbative QCD mechanism and does not require exotic assumptions. This overview outlines how several key measurements each partially constrain shower-medium interaction physics and how from the sum of those the outlines of the mechanism of jet quenching can be deduced. Most current jet results from LHC can be naturally understood in this picture. A short summary of what can be established about the nature of parton-medium interaction with current data is given in the end.

  7. Jet Production at CDF

    SciTech Connect

    M. Martinez

    2003-01-15

    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.

  8. Cryogenically assisted abrasive jet micromachining of polymers

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

    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.

  9. Jet lag modification.

    PubMed

    Simmons, Emily; McGrane, Owen; Wedmore, Ian

    2015-01-01

    Athletes often are required to travel for sports participation, both for practice and competition. A number of those crossing multiple time zones will develop jet lag disorder with possible negative consequences on their performance. This review will discuss the etiology of jet lag disorder and the techniques that are available to shorten or minimize its effects. This includes both pharmacological and nonpharmacological approaches. PMID:25757008

  10. Rapidity Gaps Between Jets

    Microsoft Academic Search

    J. M. Butterworth; M. E. Hayes; M. H. Seymour; L. E. Sinclair

    1996-01-01

    An excess of events with a rapidity gap between jets, over what would be\\u000aexpected from non-diffractive processes, has been observed at HERA. A process\\u000abased on a perturbative QCD calculation of colour singlet exchange has been\\u000aadded to HERWIG. With this addition, HERWIG is able to describe the number of\\u000aevents with a gap between jets over the number

  11. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    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

    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.

  12. Electrokinetic Power Generation from Liquid Water Microjets

    SciTech Connect

    Duffin, Andrew M.; Saykally, Richard J.

    2008-02-15

    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%.

  13. Hydrodynamic and hydromagnetic stability of a finite hollow jet

    NASA Astrophysics Data System (ADS)

    Elazab, Samia S.

    1990-07-01

    The hydrodynamic and hydromagnetic stability of a gas jet coaxial with a liquid cylinder (with solid cylindrical edge) acted upon the capillary, electromagnetic and inertia liquid forces is presented. A general eigenvalue relation is derived and verified, using the conservation energy principle. The analytical stability results are confirmed numerically and interpreted physically. The surface tension is destabilizing only in the axisymmetric mode if the perturbed wavelength is longer than the circumference of the gas jet and stable to all other deformations. The thicker the thickness of the liquid layer the greater is the destabilizing influence of the surface tension. The magnetic field is stabilizing for all short and long wavelengths whatever is the intensity of the applied basic magnetic field. The capillary instability decreases with increasing intensity of the magnetic field. Above a certain value of the basic magnetic field the capillary instability is completely suppressed and stability arises.

  14. Quantitative acetone PLIF measurements of jet mixing with synthetic jet actuators

    NASA Astrophysics Data System (ADS)

    Ritchie, Brian D.

    Fuel-air mixing enhancement in axisymmetric jets using an array of synthetic jet actuators around the perimeter of the flows (primarily parallel to the flow axis) was investigated using planar laser-induced fluorescence of acetone. The synthetic jets are a promising new mixing control and enhancement technology with a wide range of capabilities. An image correction scheme that improved on current ones was applied to the images acquired to generate quantitative mixing measurements. Both a single jet and coaxial jets were tested, including different velocity ratios for the coaxial jets. The actuators run at a high frequency (˜1.2 kHz), and were tested with all of them on and in other geometric patterns. In addition, amplitude modulation was imposed at a lower frequency (10-100 Hz). The actuators generated small-scale structures in the outer (and inner, for the coaxial jets) mixing layers. These structures significantly enhanced the mixing in the near field (x/D < 1) of the jets, which would be useful for correcting an off-design condition in a combustor. The amplitude modulation generated large-scale structures that became apparent farther downstream (x/D > 1). The impulse at the start of the duty cycle was responsible for creating the structures. The large structures contained broad regions of uniformly mixed fluid, and also entrained fluid significantly. In addition, highly asymmetric forcing geometries displayed the power of the actuators to control the spatial distribution of jet fluid. This spatial control is important for the correction of hot spots in the pattern factor. In order to extend quantitative acetone PLIF to two-phase flows, the remaining unknown photophysical properties of acetone were identified. Tests showed that the technique could simultaneously capture acetone vapor and acetone droplets. A model of droplet fluorescence was developed, and applied to images acquired in a dilute spray. The sensitivity of the model to the value of the unknowns was evaluated, including a best and worst case. The results revealed that several liquid acetone photophysical properties must be measured for the further development of the technique, especially the phosphorescence yield. Quantitative two-phase acetone PLIF will provide a powerful new tool for studying spray flows.

  15. Explosive boiling of liquid nitrogen

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  16. B-jets and z + b-jets at CDF

    SciTech Connect

    Jeans, Daniel; /Rome U.

    2006-06-01

    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.

  17. The M87 Jet. "Rosetta Stone" of AGN Jets

    NASA Astrophysics Data System (ADS)

    Nakamura, Masanori; Asada, Keiichi

    2013-12-01

    We investigate the structure and dynamics of the M87 jet based on multi-frequency VLBI observations and MHD jet theories. Millimeter VLBI cores are considered as innermost jet emissions. The jet structure up to ~ 105 rs is described as a parabolic streamline, indicating the lateral expansion under a confinement by the stratified ISM. Thus, the jet collimation maintains in five orders of magnitude in the distance starting from the vicinity of the supermassive black hole (SMBH), less than 10 rs. We here examine the jet parabolic structure in order to identify the property of a bulk acceleration; observed sub-to-superluminal motions indicate an MHD acceleration from non-relativistic to relativistic regimes. We propose that the M87 jet consists of Poynting-flux dominated flows, powered by nonlinear torsional Alfvén waves. Future sub-mm VLBI observations play an important role in resolving the origin of the M87 jets.

  18. Aeroacoustic Experiments with Twin Jets

    NASA Technical Reports Server (NTRS)

    Bozak, Richard F.; Henderson, Brenda S.

    2012-01-01

    While the noise produced by a single jet is azimuthally symmetric, multiple jets produce azimuthally varying far-field noise. The ability of one jet to shield another reduces the noise radiated in the plane of the jets, while often increasing the noise radiated out of the plane containing the jets. The present study investigates the shielding potential of twin jet configurations over subsonic and over-expanded supersonic jet conditions with simulated forward flight. The experiments were conducted with 2 in. throat diameter nozzles at four jet spacings from 2.6d to 5.5d in center-to-center distance, where d is the nozzle throat diameter. The current study found a maximum of 3 dB reduction in overall sound pressure level relative to two incoherent jets in the peak jet noise direction in the plane containing the jets. However, an increase of 3 dB was found perpendicular to the plane containing the jets. In the sideline direction, shielding is observed for all jet spacings in this study.

  19. The Twin Jet Nebula

    NASA Technical Reports Server (NTRS)

    1997-01-01

    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.

  20. Instability of rectangular jets

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  1. Modified shielding jet model for twin-jet shielding analysis

    E-print Network

    Gilbride, Jennifer Frances

    1983-01-01

    of the incident sound waves. Equivalently, these three factors may be summarized in terms of the barrier effectiveness and defined in the following way. The function of a barrier is to provide a "shadow zone", or reduced noise region, on the side of the jet... contributes to increased shielding at the higher frequencies on the shadow side of the jet. 3). Temperature Effects The hot jet presents a significant temperature gradient between the shielding jet and the surrounding medium. There is also considerable...

  2. Relativistic AGN jets I. The delicate interplay between jet structure, cocoon morphology and jet-head propagation

    NASA Astrophysics Data System (ADS)

    Walg, S.; Achterberg, A.; Markoff, S.; Keppens, R.; Meliani, Z.

    2013-08-01

    Astrophysical jets reveal strong signs of radial structure. They suggest that the inner region of the jet, the jet spine, consists of a low-density, fast-moving gas, while the outer region of the jet consists of a more dense and slower moving gas, called the jet sheath. Moreover, if jets carry angular momentum, the resultant centrifugal forces lead to a radial stratification. Current observations are not able to fully resolve the radial structure, so little is known about its actual profile. We present three active galactic nuclei jet models in 2.5D of which two have been given a radial structure. The first model is a homogeneous jet, the only model that does not carry angular momentum; the second model is a spine-sheath jet with an isothermal equation of state; and the third jet model is a (piecewise) isochoric spine-sheath jet, with constant but different densities for jet spine and jet sheath. In this paper, we look at the effects of radial stratification on jet integrity, mixing between the different jet components and global morphology of the jet-head and surrounding cocoon. We consider steady jets that have been active for 23 Myr. All jets have developed the same number of strong internal shocks along their jet axis at the final time of simulation. These shocks arise when vortices are being shed by the jet-head. We find that all three jets maintain their stability all the way up to the jet-head. The isothermal jet maintains part of its structural integrity at the jet-head where the distinction between jet spine and jet sheath material can still be made. In this case, mixing between jet spine and jet sheath within the jet is fairly inefficient. The isochoric jet, on the other hand, loses its structural jet integrity fairly quickly after the jet is injected. At its jet-head, little structure is maintained and the central part of the jet predominantly consists of jet sheath material. In this case, jet spine and jet sheath material mix efficiently within the jet. We find that the propagation speed for all three models is less than expected from simple theoretical predictions. We propose this is due to an enlarged cross-section of the jet which impacts with the ambient medium. We show that in these models, the effective surface area is 16 times as large in the case of the homogeneous jet, 30 times as large in the case of the isochoric jet and can be up to 40 times as large in the case of the isothermal jet.

  3. An advection-diffusion model for the dispersion in quasi two-dimensional steady turbulent jets

    NASA Astrophysics Data System (ADS)

    Landel, Julien R.; Caulfield, C. P.; Woods, Andrew W.

    2011-11-01

    The study of turbulent jets in relatively enclosed geometries is relevant to many chemical engineering processes. Predicting the concentration of chemical reactants in time and space requires a good understanding of the jet dynamics. We have considered experimentally and theoretically the behaviour of liquid jets in a quasi-Hele-Shaw cell, where the jets are constrained in a narrow gap whose width is two orders of magnitude smaller than the length-scales of the other two flow dimensions. In this configuration, the dynamics shown by the jets is very rich. Detailed examinations of instantaneous structures of the flow reveal a high-speed sinuous core at the centre of the jet and large vortical structures on each side, which we analyse quantitatively using a variety of techniques (particle image velocimetry and dye experiments). These structures have a large impact on the mixing and dispersion properties of the jet. We propose a one-dimensional advection-diffusion model to account for the vertical dispersion in the jet. The diffusion coefficient assumed in the model is based on our understanding of the large-scale structures of these jets. The model is solved analytically using a similarity form in the case of a finite-volume release of tracers in the jet. The theoretical predictions and the experimental measurements show very good agreement.

  4. A Comparison between Plasma Synthetic Jets and Conventional Jets

    Microsoft Academic Search

    Arvind Santhanakrishnan; Jamey Jacob

    2007-01-01

    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

  5. Hypersonic jet control effectiveness

    NASA Astrophysics Data System (ADS)

    Kumar, D.; Stollery, J. L.; Smith, A. J.

    The present study aims to identify some of the parameters which determine the upstream extent and the lateral spreading of the separation front around an under-expanded transverse jet on a slender blunted cone. The tests were conducted in the Cranfield hypersonic facility at M? = 8.2, Re? /cm = 4.5 to 9.0 × 104 and at M? = 12.3, Re? /cm = 3.3 × 104. Air was used as the working gas for both the freestream and the jet. Schlieren pictures were used for the visualisation of the three-dimensional structures around the jet. Pressure, normal force and pitching moment measurements were conducted to quantitatively study the interaction region and its effects on the vehicle. An analytical algorithm has been developed to predict the shape of the separation front around the body.

  6. Renewable jet fuel.

    PubMed

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

    2014-04-01

    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

  7. 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

  8. Neutron emission profiles and energy spectra measurements at JET

    NASA Astrophysics Data System (ADS)

    Giacomelli, L.; Conroy, S.; Belli, F.; Gorini, G.; Horton, L.; Joffrin, E.; Lerche, E.; Murari, A.; Popovichev, S.; Riva, M.; Syme, B.; JET EFDA Contributors

    2014-08-01

    The Joint European Toras (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or DT plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  9. Neutron emission profiles and energy spectra measurements at JET

    SciTech Connect

    Giacomelli, L. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB, United Kingdom and Department of Physics, Università degli Studi di Milano-Bicocca, Milano (Italy); Conroy, S. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB, United Kingdom and Department of Physics and Astronomy, Uppsala University, Uppsala (Sweden); Belli, F.; Riva, M. [Associazione EURATOM-ENEA sulla Fusione, Roma (Italy); Gorini, G. [Department of Physics, Università degli Studi di Milano-Bicocca, Milano, Italy and Istituto di Física del Plasma Piero Caldirola, Milan (Italy); Horton, L.; Joffrin, E.; Lerche, E.; Murari, A.; Popovichev, S.; Syme, B. [JET-EFDA, Culham Science Centre, Abingdon, 0X14 3DB (United Kingdom); Collaboration: JET EFDA Contributors

    2014-08-21

    The Joint European Toras (JET, Culham, UK) is the largest tokamak in the world. It is devoted to nuclear fusion experiments of magnetic confined Deuterium (D) or Deuterium-Tritium (DT) plasmas. JET has been upgraded over the years and recently it has also become a test facility of the components designed for ITER, the next step fusion machine under construction in Cadarache (France). JET makes use of many different diagnostics to measure the physical quantities of interest in plasma experiments. Concerning D or DT plasmas neutron production, various types of detectors are implemented to provide information upon the neutron total yield, emission profile and energy spectrum. The neutron emission profile emitted from the JET plasma poloidal section is reconstructed using the neutron camera (KN3). In 2010 KN3 was equipped with a new digital data acquisition system capable of high rate neutron measurements (<0.5 MCps). A similar instrument will be implemented on ITER and it is currently in its design phase. Various types of neutron spectrometers with different view lines are also operational on JET. One of them is a new compact spectrometer (KM12) based on organic liquid scintillating material which was installed in 2010 and implements a similar digital data acquisition system as for KN3. This article illustrates the measurement results of KN3 neutron emission profiles and KM 12 neutron energy spectra from the latest JET D experimental campaign C31.

  10. The JPL Direct Methanol Liquid-feed PEM Fuel Cell

    NASA Technical Reports Server (NTRS)

    Halpert, G.; Surampudi, S.

    1994-01-01

    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:...

  11. On magnetohydrodynamic solitons in jets

    NASA Technical Reports Server (NTRS)

    Roberts, B.

    1987-01-01

    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.

  12. Riding the Jet Stream

    NSDL National Science Digital Library

    2012-08-03

    Students watch or read a weather report, and draw the position of the jet stream on a map. This worksheet includes questions that help students learn the role of the jet stream in the generation of weather in the continental U.S. The resource is part of the teacher's guide accompanying the video, NASA Why Files: The Case of the Mysterious Red Light. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

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

    SciTech Connect

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

    1999-07-01

    Coal-based liquids have a great potential as precursors for advanced jet fuels that meet the more stringent thermal stability requirements for the future high-Mach jet aircraft. In current commercial planes, the fuel may be exposed to temperatures up to 300 C. However, as the flight speed will be increased to high Mach numbers, the fuel is expected to experience temperatures as high as 480 C (900 F) in the future, since the jet fuel also functions as the main coolant for the different electronic and mechanical parts of the aircraft. Even though the residence time at such elevated temperatures is expected to be fairly short (matter of minutes), the jet fuels presently used have shown to form solid deposits that can lead to catastrophic malfunction of the jet aircraft. The current jet fuels are petroleum-derived and consequently rich in linear alkanes, which are highly susceptible to pyrolytic cracking resulting in coking. The thermal stability of a jet fuel in the pyrolytic regime can be greatly enhanced by utilizing liquids rich in cyclo-alkanes. This is the case for hydro-treated coal-derived liquids, where the aromatic structures have been transformed over to their corresponding cyclo-alkanes. An additional problem with jet fuels is the presence of dissolved oxygen (from air), which reacts with the fuel during the autoxidative regime (150--250 C) before the fuel and its oxygenated reaction products enter the pyrolytic regime (400--500 C). Accordingly, this study compares the thermal stability of a linear alkane (tetradecane), a cyclo-alkane (decahydronaphthalene) and a coal-derived jet-fuel as they go through the autoxidative regime into the pyrolytic regime. Differences in chemical reactivity between the linear- and cyclo-alkane have been related to the stability of the coal-derived jet-fuel.

  14. Combined plasma/liquid cleaning of substrates

    DOEpatents

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

    2003-04-15

    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.

  15. Jet-images: computer vision inspired techniques for jet tagging

    NASA Astrophysics Data System (ADS)

    Cogan, Josh; Kagan, Michael; Strauss, Emanuel; Schwarztman, Ariel

    2015-02-01

    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 gluoninitiated 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.

  16. Jet-Images: Computer Vision Inspired Techniques for Jet Tagging

    E-print Network

    Josh Cogan; Michael Kagan; Emanuel Strauss; Ariel Schwarztman

    2015-01-08

    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.

  17. Particle jet formation during explosive dispersal of solid particles

    NASA Astrophysics Data System (ADS)

    Frost, David L.; Grégoire, Yann; Petel, Oren; Goroshin, Samuel; Zhang, Fan

    2012-09-01

    Previous experimental studies have shown that when a layer of solid particles is explosively dispersed, the particles often develop a non-uniform spatial distribution. The instabilities within the particle bed and at the particle layer interface likely form on the timescale of the shock propagation through the particles. The mesoscale perturbations are manifested at later times in experiments by the formation of coherent clusters of particles or jet-like particle structures, which are aerodynamically stable. A number of different mechanisms likely contribute to the jet formation including shock fracturing of the particle bed and particle-particle interactions in the early stages of the dense gas-particle flow. Aerodynamic wake effects at later times contribute to maintaining the stability of the jets. The experiments shown in this fluid dynamics video were carried out in either spherical or cylindrical geometry and illustrate the formation of particle jets during the explosive dispersal process. The number of jet-like structures that are generated during the dispersal of a dry powder bed is compared with the number formed during the dispersal of the same volume of water. The liquid dispersal generates a larger number of jets, but they fragment and dissipate sooner. When the particle bed is saturated with water and explosively dispersed, the number of particle jets formed is larger than both the dry powder and pure water charges. More extensive experiments that explore the effect of particle size, density and the mass ratio of explosive to particles on the susceptibility for jet formation are reported in Frost et al. (Proc. of 23rd ICDERS, Irvine, CA, 2011).

  18. Jet Screech Noise Computation

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Hultgren, Lennart S.

    2003-01-01

    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.

  19. Beating jet lag

    Microsoft Academic Search

    C J Milne; M H Fuard

    2007-01-01

    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.

  20. The physics of jets

    SciTech Connect

    Hofmann, W.

    1987-09-01

    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.

  1. 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 ...

  2. Instabilities of rotating jets

    E-print Network

    Zahniser, Russell, 1982-

    2004-01-01

    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 ...

  3. Control of jet engines

    Microsoft Academic Search

    H Austin Spang III; Harold Brown

    1999-01-01

    Feedback control has always been an essential part of jet engines because they operate at or near their mechanical or aerothermal limitations. In this paper, the basics of controlling an engine while satisfying numerous constraints will be reviewed. The emphasis will be on commercial engines though most of the material is also applicable to military engines. In the first part,

  4. The Jet Travel Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2007-01-01

    Airplane travelers are dismayed by the long lines and seemingly chaotic activities that precede boarding a full airplane. Surely, the one who can solve this problem is going to make many travelers happy. This article describes the Jet Travel Challenge, an activity that challenges students to create some alternatives to this now frustrating…

  5. 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.

  6. Upgrading jet turbine technology

    Microsoft Academic Search

    Valenti

    1995-01-01

    This article describes a joint government\\/industry program that is developing a new breed of turbine components, including bearings, blades, and seals, to double the propulsion capacity of both military and commercial jet engines. Although the tensions of the Cold War have receded with the demise of the Soviet Union, the US continually seeks to improve the operational readiness of its

  7. Rapidity-dependent jet vetoes

    NASA Astrophysics Data System (ADS)

    Gangal, Shireen; Stahlhofen, Maximilian; Tackmann, Frank J.

    2015-03-01

    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'+N L O order with the recent differential cross-section measurement by the ATLAS experiment in the H ?? ? channel, finding good agreement. We also propose that these jet-veto variables can be measured and tested against theory predictions in other Standard Model processes, such as Drell-Yan, diphoton, and weak diboson production.

  8. Jet propagation through energetic materials

    SciTech Connect

    Pincosy, P; Poulsen, P

    2004-01-08

    In applications where jets propagate through energetic materials, they have been observed to become sufficiently perturbed to reduce their ability to effectively penetrate subsequent material. Analytical calculations of the jet Bernoulli flow provides an estimate of the onset and extent of such perturbations. Although two-dimensional calculations show the back-flow interaction pressure pulses, the symmetry dictates that the flow remains axial. In three dimensions the same pressure impulses can be asymmetrical if the jet is asymmetrical. The 3D calculations thus show parts of the jet having a significant component of radial velocity. On the average the downstream effects of this radial flow can be estimated and calculated by a 2D code by applying a symmetrical radial component to the jet at the appropriate position as the jet propagates through the energetic material. We have calculated the 3D propagation of a radio graphed TOW2 jet with measured variations in straightness and diameter. The resultant three-dimensional perturbations on the jet result in radial flow, which eventually tears apart the coherent jet flow. This calculated jet is compared with jet radiographs after passage through the energetic material for various material thickness and plate thicknesses. We noted that confinement due to a bounding metal plate on the energetic material extends the pressure duration and extent of the perturbation.

  9. Rapidity-Dependent Jet Vetoes

    E-print Network

    Shireen Gangal; Maximilian Stahlhofen; Frank J. Tackmann

    2014-12-15

    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.

  10. A stochastic model for the formation of turbulent liquid sprays in free shear flow fields

    Microsoft Academic Search

    David Joseph Schmidt

    2002-01-01

    The formation and dispersion of turbulent liquid sprays in an axisymmetric jet was investigated numerically via a coupled, three-dimensional, joint Lagrangian-Eulerian stochastic method. The liquid spray is modeled as a series of continuously injected droplets into the turbulent flow which issues from an axisymmetric atomizer nozzle. Motions of nondeforming spherical liquid droplets and deforming ellipsoidal droplets are examined. Equations of

  11. Flow cytometer jet monitor system

    DOEpatents

    Van den Engh, Ger (Seattle, WA)

    1997-01-01

    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.

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

    SciTech Connect

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

    2014-01-01

    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.

  13. Transport, dispersion and mixing in quasi-two-dimensional steady jets

    NASA Astrophysics Data System (ADS)

    Landel, J. R.; Caulfield, C. P.; Woods, Andrew W.

    2010-11-01

    The study of turbulent jets in relatively enclosed geometries is relevant to many chemical engineering processes. Predicting the concentration of chemical reactants in time and space requires a good understanding of the jet dynamics. We consider experimentally and theoretically the behaviour of liquid jets in a quasi-Hele-Shaw cell, where the jets are constrained in a narrow gap whose width is two orders of magnitude smaller than the other two flow dimensions. Classical theoretical models for plane jets are in excellent agreement with time-averaged experimental results obtained using both dyed jets and PIV techniques. Detailed examination of instantaneous structures of the flow reveals a high-speed sinuous core at the centre of the jet and large vortical structures on each side, which we analyse quantitatively using a variety of techniques. These structures have a large impact on the mixing and dispersion properties of the jet. We use a virtual-particle-tracking technique to assess and understand this effect. Comparisons between the instantaneous and the time-averaged velocity field show the importance of the inherently time-dependent vortical structures in the mixing and stretching of the fluid, substantially modifying the mixing and (vertical) dispersion within the jet.

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

    SciTech Connect

    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

    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.

  15. Investigation of the gas-jet ejector in KamAZ trucks

    Microsoft Academic Search

    L. Y. Shkret; A. I. Berezea; A. N. Lobkov

    1984-01-01

    This article considers the possibility of using gas-jet vacuum pumps in tank trucks for transporting liquids (water) at drilling sites. The discharge system of the KamAZ trucks can be reliably sealed by an engine brake, an important prerequisite of reliable operation of a gas-jet ejector that is switched on when the tank is being filled. The ejector consists of a

  16. Applicability of the hydrodynamic approximation to current-carrying plasma jets during their radial expansion

    Microsoft Academic Search

    Evgeny Gidalevich; Raymond L. Boxman; Samuel Goldsmith

    2001-01-01

    Supersonic spherically symmetric vacuum-arc plasma jets are considered using a two-liquid model. The jet starts from a radial distance of 3×10-3 m from the cathode surface with a radial directed electric current of 50-1000 A. Joule heating of the electron component and heat transfer to the ion component were calculated. The spatial distribution of plasma density, velocity, and electron and

  17. Paper-based optofluidic SERS using ink-jet-printed substrates

    Microsoft Academic Search

    Wei W. Yu; Ian M. White

    2011-01-01

    We report the development of a novel, low-cost surface enhanced Raman spectroscopy (SERS) substrate that is fabricated by ink-jet-printing silver nanostructures into cellulose paper. Analysis of a liquid sample is performed by spotting a 1 microliter droplet onto the printed SERS substrate. The droplet is contained within a small area of the SERS substrate by ink-jet-printing hydrophobic barriers to define

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

    NASA Astrophysics Data System (ADS)

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

    1984-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  20. Simultaneous velocity and concentration field measurements of passive-scalar mixing in a confined rectangular jet

    Microsoft Academic Search

    Hua Feng; Michael G. Olsen; James C. Hill; Rodney O. Fox

    2007-01-01

    Simultaneous velocity and concentration fields in a confined liquid-phase rectangular jet with a Reynolds number based on\\u000a the hydraulic diameter of 50,000 (or 10,000 based on the velocity difference between streams and the jet exit dimension) and\\u000a a Schmidt number of 1,250 were obtained by means of a combined particle image velocimetry (PIV) and planar laser-induced fluorescence\\u000a (PLIF) system. Data

  1. Liquid injection plasma deposition method and apparatus

    DOEpatents

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

    1999-05-25

    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.

  2. Liquid injection plasma deposition method and apparatus

    DOEpatents

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

    1999-01-01

    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.

  3. High air volume to low liquid volume aerosol collector

    DOEpatents

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

    2003-01-01

    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.

  4. Fixing Time Of Ink-Jet Inks On Plain Paper

    NASA Astrophysics Data System (ADS)

    Ozaki, Mitsuo; Takada, Noboru; Kiyota, Kohei

    1989-07-01

    We investigated water-based ink-jet inks which fix quickly on plain paper. Ink-jet inks have liquid components which evaporate slowly to prevent the print head nozzles from clogging. The fixing time of these inks is too long for printing on plain paper. Inks cannot penetrate paper which contains a sizing agent, which increases the paper's resistance to liquids. The most widely used sizing agent is rosin. We attempted to shorten fixing time by including in the ink, a component for dissolving rosin. The glycols used in the ink are useful because they evaporate slowly. We determined the relationship between the solubility of the ink for sizing agents, rosin, and the time needed for fixing and penetration. The higher the solubility of a glycol for rosin, the faster the penetration of the ink containing it. Hexylene glycol dissolves rosin over 70 wt%, and ink containing over 15 wt% hexylene glycol penetrated plain paper within 5 seconds.

  5. Integrated coke, asphalt and jet fuel production process and apparatus

    SciTech Connect

    Shang, Jer Yu.

    1989-10-17

    A process and apparatus for the production of coke, asphalt and jet fuel from 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 some 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 these products from materials such as coal, oil shale and tar sands. 1 fig.

  6. Jet decorrelation and jet shapes at the Tevatron

    SciTech Connect

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

    1996-07-01

    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.

  7. Jet-Environment Interactions as Diagnostics of Jet Physics

    NASA Astrophysics Data System (ADS)

    Heinz, Sebastian

    2014-09-01

    In this chapter, we will explore the interaction of jets with their environments. Jets can transport a sizable fraction of accretion energy away from black holes and neutron stars. Because they are collimated, they can travel to distances far beyond the gravitational sphere of influence of the black hole. Yet, their interaction with the interstellar and intergalactic medium must eventually halt their advance and dissipate the energy they carry. The termination of the jet, and the inflation of large scale cavities of relativistic plasma offers one of the most powerful ways to constrain the physics of jets. In this chapter, we will review the inflation of radio lobes, the propagation of hot spots, the creation of shells and cavities, and the bending of jet by proper motion through their environment, both in the context of AGN jets and microquasars.

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

    PubMed Central

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

    2014-01-01

    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

  9. SparkJet Efficiency

    NASA Technical Reports Server (NTRS)

    Golbabaei-Asl, Mona; Knight, Doyle; Anderson, Kellie; Wilkinson, Stephen

    2013-01-01

    A novel method for determining the thermal efficiency of the SparkJet is proposed. A SparkJet is attached to the end of a pendulum. The motion of the pendulum subsequent to a single spark discharge is measured using a laser displacement sensor. The measured displacement vs time is compared with the predictions of a theoretical perfect gas model to estimate the fraction of the spark discharge energy which results in heating the gas (i.e., increasing the translational-rotational temperature). The results from multiple runs for different capacitances of c = 3, 5, 10, 20, and 40 micro-F show that the thermal efficiency decreases with higher capacitive discharges.

  10. Ghost-Jet

    Microsoft Academic Search

    Alexis B Sellas

    2011-01-01

    GHOST-JET is a collection of poems rooted in the lyrical tradition, often juxtaposing images of the natural world--the human body, insects, the Florida terrain--against images of surrealism--ethereal spirits, monsters, dreamscapes--in order to create metaphorical leaps of the imagination. In these poems there is the world as we know it and the world on the peripheral--zombies and babies turning into crocodiles,

  11. Alternative jet aircraft fuels

    NASA Technical Reports Server (NTRS)

    Grobman, J.

    1979-01-01

    Potential changes in jet aircraft fuel specifications due to shifts in supply and quality of refinery feedstocks are discussed with emphasis on the effects these changes would have on the performance and durability of aircraft engines and fuel systems. Combustion characteristics, fuel thermal stability, and fuel pumpability at low temperature are among the factors considered. Combustor and fuel system technology needs for broad specification fuels are reviewed including prevention of fuel system fouling and fuel system technology for fuels with higher freezing points.

  12. Displacement amplified synthetic jets

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  13. Plunging Plates Cause a Stir.

    ERIC Educational Resources Information Center

    Weisburd, Stefi

    1986-01-01

    Reviews current ideas and research findings related to the flow patterns of mantle rocks. Highlights the components of the two-layer convection and whole-mantle models of mantle flow. Proposes that mantle flow is the key to understanding how the earth has cooled and chemically evolved. (ML)

  14. Synthetic Jet Propulsion for Small Underwater Vehicles

    Microsoft Academic Search

    Annmarie Polsenberg Thomas; Michele Milano; Maxwell Grazier G'sell; Kathleen Fischer; Joel W. Burdick

    2005-01-01

    This paper proposes a new synthetic jet actuation concept for small, low speed, highly maneuverable AUVs. Synthetic jet thrusters, which produce jets of vortex rings, are inspired by the pulsatile jet propulsion of salps, jellyfish, and squid. To assess the potential utility of this scheme, we developed synthetic jet actuator prototypes, and verified their function via both force measurement and

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  16. Magnetic reconnection acceleration of astrophysical jets for different jet geometries

    NASA Astrophysics Data System (ADS)

    Chen, A.-Ming; Rui, Li-Ming

    2015-04-01

    The acceleration mechanisms of relativistic jets are of great importance for understanding various astrophysical phenomena such as gamma-ray bursts, active galactic nuclei and microquasars. One of the most popular scenarios is that the jets are initially Poynting-flux dominated and succumb to magnetohydrodynamic instability leading to magnetic reconnections. We suggest that the reconnection timescale and efficiency could strongly depend on the geometry of the jet, which determines the length scale on which the orientations of the field lines change. In contrast to a usually-assumed conical jet, the acceleration of a collimated jet can be found to be more rapid and efficient (i.e. a much more highly saturated Lorentz factor can be reached) while the jets with lateral expansion show the opposite behavior. The shape of the jet could be formed due to the lateral squeezing on the jet by the stellar envelope of a collapsing massive star or the interaction of the jet with stellar winds. Supported by the National Natural Science Foundation of China.

  17. Jet dynamics at Lone Star Geyser, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Karlstrom, L.; Rudolph, M. L.; Vandemeulebrouck, J.; Murphy, F.; Hurwitz, S.; Manga, M.; Sohn, R. A.; Johnston, M. J.

    2011-12-01

    Geysers provide a natural laboratory to study multiphase eruption processes and the geophysical signals that can be measured before, during, and after an eruption. As part of a field study at Lone Star Geyser, Yellowstone National Park in September, 2010, we recorded multiple consecutive eruptions with visible and infrared video and an audio microphone. These measurements, along with water discharge measurements in outflow streams, allow us to constrain eruptive liquid and steam volumes and calculate aspects of jet dynamics and energetics . We perform Particle Image velocimetry (PIV) analysis of high-speed visible video images to extract maximum jet velocity and height throughout an eruption. We find that the time and frequency domain structure of maximum velocity is similar to that of median jet temperature and amplitude of acoustic emissions. We correlate visible and infrared video to estimate the mass fraction of steam versus liquid throughout an eruption, and use this to calculate an energy budget for the geyser. The clear transition from liquid to steam dominated flow during eruption is mirrored in the frequency domain, likely reflecting a shift in the sound speed of the mixture and a transition towards choked conditions during eruptions. However unsteadiness in the flow implies that this condition is not always met.

  18. Interfacial deformation and jetting of a magnetic fluid

    E-print Network

    Afkhami, Shahriar; Griffiths, Ian M

    2015-01-01

    An attractive technique for forming and collecting aggregates of magnetic material at a liquid--air interface by an applied magnetic field gradient was recently addressed theoretically and experimentally [Soft Matter, (9) 2013, 8600-8608]: when the magnetic field is weak, the deflection of the liquid--air interface has a steady shape, while for sufficiently strong fields, the interface destabilizes and forms a jet that extracts magnetic material. Motivated by this work, we develop a numerical model for the closely related problem of solving two-phase Navier--Stokes equations coupled with the static Maxwell equations. We computationally model the forces generated by a magnetic field gradient produced by a permanent magnet and so determine the interfacial deflection of a magnetic fluid (a pure ferrofluid system) and the transition into a jet. We analyze the shape of the liquid--air interface during the deformation stage and the critical magnet distance for which the static interface transitions into a jet. We d...

  19. W + jet production at CDF

    SciTech Connect

    Messina, Andrea; /INFN, Rome

    2006-10-01

    A measurement of W {yields} e{nu} + n-jet cross sections in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab in Run II (CDF II) is presented. The measurement is based on an integrated luminosity of 320 pb{sup -1}, and includes events with up to 4 or more jets. In each jet multiplicity sample the differential and cumulative cross sections with respect to the transverse energy of the i{sup th} jet are measured. For W+ {ge} 2 jets the differential cross section with respect to the 2-leading jets invariant mass m{sub j{sub 1}j{sub 2}} and angural separation {Delta} R{sub j{sub 1}j{sub 2}} is also reported. The data are compared to predictions from Monte Carlo simulations.

  20. Overview of JET results

    NASA Astrophysics Data System (ADS)

    Romanelli, F.; JET-EFDA Contributors; Kamendje, R.

    2009-10-01

    Since the last IAEA conference, the scientific programme of JET has focused on the qualification of the integrated operating scenarios for ITER and on physics issues essential for the consolidation of design choices and the efficient exploitation of ITER. Particular attention has been given to the characterization of the edge plasma, pedestal energy and edge localized modes (ELMs), and their impact on plasma facing components (PFCs). Various ELM mitigation techniques have been assessed for all ITER operating scenarios using active methods such as resonant magnetic field perturbation, rapid variation of the radial field and pellet pacing. In particular, the amplitude and frequency of type I ELMs have been actively controlled over a wide parameter range (q95 = 3-4.8, ?N <= 3.0) by adjusting the amplitude of the n = 1 external perturbation field induced by error field correction coils. The study of disruption induced heat loads on PFCs has taken advantage of a new wide-angle viewing infrared system and a fast bolometer to provide a detailed account of time, localization and form of the energy deposition. Specific ITER-relevant studies have used the unique JET capability of varying the toroidal field (TF) ripple from its normal low value ?BT = 0.08% up to ?BT = 1% to study the effect of TF ripple on high confinement-mode plasmas. The results suggest that ?BT < 0.5% is required on ITER to maintain adequate confinement to allow QDT = 10 at full field. Physics issues of direct relevance to ITER include heat and toroidal momentum transport, with experiments using power modulation to decouple power input and torque to achieve first experimental evidence of inward momentum pinch in JET and determine the threshold for ion temperature gradient driven modes. Within the longer term JET programme in support of ITER, activities aiming at the modification of the JET first wall and divertor and the upgrade of the neutral beam and plasma control systems are being conducted. The procurement of all components will be completed by 2009 with the shutdown for the installation of the beryllium wall and tungsten divertor extending from summer 2009 to summer 2010.

  1. Jet initiation of PBX 9502

    SciTech Connect

    McAfee, J.M.

    1987-07-01

    This report details the progress of an effort to determine the quantitative aspects of the initiation of PBX 9502 (95% TATB, 5% Kel-F 800) by copper jets. The particular jet used was that produced by the LAW warhead (66-mm diameter, 42/sup 0/ angle cone, copper-lined, conical shaped charge). Fifteen experiments, in various configurations, have been fired to define the essential parameters for quantitatively measuring the jet performance and initiation of bare PBX 9502. 7 refs., 8 figs.

  2. Heavy Quark Fragmenting Jet Functions

    E-print Network

    Christian W. Bauer; Emanuele Mereghetti

    2013-12-19

    Heavy quark fragmenting jet functions describe the fragmentation of a parton into a jet containing a heavy quark, carrying a fraction of the jet momentum. They are two-scale objects, sensitive to the heavy quark mass, $m_Q$, and to a jet resolution variable, $\\tau_N$. We discuss how cross sections for heavy flavor production at high transverse momentum can be expressed in terms of heavy quark fragmenting jet functions, and how the properties of these functions can be used to achieve a simultaneous resummation of logarithms of the jet resolution variable, and logarithms of the quark mass. We calculate the heavy quark fragmenting jet function $\\mathcal G_Q^Q$ at $\\mathcal O(\\alpha_s)$, and the gluon and light quark fragmenting jet functions into a heavy quark, $\\mathcal G_g^Q$ and $\\mathcal G_l^Q$, at $\\mathcal O(\\alpha_s^2)$. We verify that, in the limit in which the jet invariant mass is much larger than $m_Q$, the logarithmic dependence of the fragmenting jet functions on the quark mass is reproduced by the heavy quark fragmentation functions. The fragmenting jet functions can thus be written as convolutions of the fragmentation functions with the matching coefficients $\\mathcal J_{i j}$, which depend only on dynamics at the jet scale. We reproduce the known matching coefficients $\\mathcal J_{i j}$ at $\\mathcal O(\\alpha_s)$, and we obtain the expressions of the coefficients $\\mathcal J_{g Q}$ and $\\mathcal J_{l Q}$ at $\\mathcal O(\\alpha_s^2)$. Our calculation provides all the perturbative ingredients for the simultaneous resummation of logarithms of $m_Q$ and $\\tau_N$.

  3. Impeller for Water Jet Propulsion

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Marshall Space Flight Center engineers helped North American Marine Jet (NAMJ), Inc. improve the proposed design of a new impeller for jet propulsion system. With a three-dimensional computer model of the new marine jet engine blades, engineers were able to quickly create a solid ploycarbonate model of it. The rapid prototyping allowed the company to avoid many time-consuming and costly steps in creating the impeller.

  4. Field of Flow About a Jet and Effect of Jets on Stability of Jet-Propelled Airplanes

    NASA Technical Reports Server (NTRS)

    Ribner, Herbert S.

    1946-01-01

    A theoretical investigation was conducted on jet-induced flow deviation. Analysis is given of flow inclination induced outside cold and hot jets and jet deflection caused by angle of attack. Applications to computation of effects of jet on longitudinal stability and trim are explained. Effect of jet temperature on flow inclination was found small when thrust coefficient is used as criterion for similitude. The average jet-induced downwash over tail plane was obtained geometrically.

  5. Jet penetration of high explosive

    SciTech Connect

    Poulsen, P

    1999-08-11

    It is found that a transition between two flow patterns takes place in thick HE targets. In this case, the jet will initially propagate into the HE at the same rate as into an inert material of the same density. The part of the jet that has stagnated and is flowing nearly co-axially with the incoming jet (but at a much lower speed) is being forced toward the surface of the incoming jet by the pressure of the reaction products but has not as yet made contact. After it makes contact, both axial and perpendicular momentum transfer takes place between the two jet components. After this transition, a new steady state will develop for the propagating jet, with the unperturbed front of the jet propagating at a slower rate than previously. The perturbed front of the jet is still propagating at or near the original rate, having had relatively little axial momentum exchange. However, it has acquired radial momentum and is spreading out as it is propagating; it is therefore becoming less capable of penetrating downstream targets. It is the unperturbed part of the jet that is capable of penetrating downstream targets. A calculational method for predicting this case is presented in this report.

  6. Measurements of jets in ALICE

    NASA Astrophysics Data System (ADS)

    Nattrass, Christine; ALICE collaboration

    2015-03-01

    Partonic energy loss in the medium formed in heavy ion collisions results in significant modifications of jet spectra. Quantitative understanding of these modifications can constrain models for partonic energy loss in heavy ion collisions. The ALICE detector is capable of unique measurements of jets due to its low momentum tracking and particle identification capabilities. The ALICE Electromagnetic Calorimeter (EMCAL) is a key element for the measurement of fully reconstructed jets in ALICE due to its measurement of neutral particles and its triggering capabilities. Measurements of fully reconstructed jet spectra and the nuclear modification factor, RAA, in Pb-Pb collisions at = 2.76 TeV are presented.

  7. Photon + jets at D0

    E-print Network

    Lars Sonnenschein

    2009-06-15

    Photon plus jet production has been studied by the D0 experiment in Run II of the Fermilab Tevatron Collider at a centre of mass energy of sqrt{s}=1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavour jet cross sections and double parton interactions in photon plus three jet events are presented. They are based on integrated luminosities between 0.4 fb$^-1 and 1.0 fb^-1. The results are compared to perturbative QCD calculations in various approximations.

  8. Photon + jets at D0

    SciTech Connect

    Sonnenschein, Lars; /RWTH Aachen U.

    2009-06-01

    Photon plus jet production has been studied by the D0 experiment in Run II of the Fermilab Tevatron Collider at a centre of mass energy of {radical}s = 1.96 TeV. Measurements of the inclusive photon, inclusive photon plus jet, photon plus heavy flavour jet cross sections and double parton interactions in photon plus three jet events are presented. They are based on integrated luminosities between 0.4 fb{sup -1} and 1.0 fb{sup -1}. The results are compared to perturbative QCD calculations in various approximations.

  9. Jet Physics at the Tevatron

    SciTech Connect

    Bhatti, Anwar; Lincoln, Don

    2010-02-01

    Jets have been used to verify the theory of quantum chromodynamics (QCD), measure the structure of the proton and to search for the physics beyond the Standard Model. In this article, we review the current status of jet physics at the Tevatron, a {radical}s = 1.96 TeV p{bar p} collider at the Fermi National Accelerator Laboratory. We report on recent measurements of the inclusive jet production cross section and the results of searches for physics beyond the Standard Model using jets. Dijet production measurements are also reported.

  10. 21 CFR 880.5475 - Jet lavage.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Therapeutic Devices § 880.5475 Jet lavage. (a) Identification. A jet lavage is a device used to clean a wound by a pulsatile jet of sterile fluid. The device...tubing, such as an electric roller pump. (b) Classification....

  11. Quark fragmentation within an identified jet

    E-print Network

    Stewart, Iain

    We derive a factorization theorem that describes an energetic hadron h fragmenting from a jet produced by a parton i, where the jet invariant mass is measured. The analysis yields a “fragmenting jet function” Gih(s,z) that ...

  12. Jet–jet and hadron–jet correlations in hadro- and electroproduction

    Microsoft Academic Search

    P. Aurenche; Rahul Basu; M. Fontannaz

    2008-01-01

    We discuss, in the framework of perturbative QCD at next to leading order, two related observables which are usually considered\\u000a to provide tests of the BFKL dynamics: jet–jet correlations at Tevatron energies and forward particle–jet correlations at\\u000a HERA. In the first case we study the rapidity gap dependence of the azimuthal correlations and find slightly too strong correlations\\u000a at large

  13. Advanced thermally stable jet fuels development program annual report. Volume 2. Compositional factors affecting thermal degradation of jet fuels. Interim report, July 1989June 1990

    Microsoft Academic Search

    S. Eser; C. Song; H. Schobert; P. Hatcher; R. Copenhaver

    1990-01-01

    Model hydrocarbon compounds and jet fuels derived from both petroleum and coal liquids were thermally stressed in microautoclave reactors at temperatures of 350-500 degrees C. Regardless of starting material, alkylated benzenes, alkylated naphthalenes, biphenyls, and complex polycyclic aromatics are formed by this thermal stressing. The concentration of these intermediates depends on the starting material and the experimental conditions. The formation

  14. Spitting cobras: fluid jets in nature as models for technical applications

    NASA Astrophysics Data System (ADS)

    Balmert, Alexander; Hess, David; Brücker, Christoph; Bleckmann, Horst; Westhoff, Guido

    2011-04-01

    Spitting cobras defend themselves by ejecting rapid jets of venom through their fangs towards the face of an offender. To generate these jets, the venom delivery system of spitting cobras has some unique adaptations, such as prominent ridges on the surface of the venom channel. We examined the fluid acceleration mechanisms in three spitting cobra species of the genus Naja. To investigate the liquid-flow through the venom channel we built a three-dimensional 60:1 scale model. First we determined the three-dimensional structure of the channel by using microcomputer tomography. With help of the micro computer tomographical data we then created a negative form out of wax. Finally, silicon was casted around the wax form and the wax removed, resulting in a completely transparent model of the cobrás venom channel. The physical-chemical properties of the cobra venom were measured by micro rheometry and tensiometry. Thereafter, an artificial fluid with similar properties was generated. Particle image velocimetry (PIV) was performed to visualize the flow of the artificial liquid in the three-dimensional model. Our experiments show how the surface structure of the venom channel determines the liquid flow through the channel and ultimately the form of the liquid jet. Understanding the biological mechanisms of venom ejection helps to enhance industrial processes such as water jet cutting and cleaning as well as injection methods in technical and medical sectors, e.g. liquid microjet dissection in microsurgery.

  15. Market Liquidity and Funding Liquidity

    Microsoft Academic Search

    Markus K. Brunnermeier; Lasse Heje Pedersen

    2009-01-01

    We provide a model that links an asset's market liquidity (i.e., the ease with which it is traded) and traders' funding liquidity (i.e., the ease with which they can obtain funding). Traders provide market liquidity, and their ability to do so depends on their availability of funding. Conversely, traders' funding, i.e., their capital and margin requirements, depends on the assets'

  16. Effect of Stand-Off Distance on Impact Pressure of High Speed Water Jets

    NASA Astrophysics Data System (ADS)

    Sittiwong, Wuttichai; Seehanam, Wirapan; Pianthong, Kulachate; Matthujak, Anirut

    2010-06-01

    High speed liquid jets may be applied to jet cutting, drilling and cleaning. Recently, in the automotive industries, the spray injection pressure becomes higher and higher to enhance the fuel mixing for the improved combustion efficiency. However, the ultra high injection pressure may cause the damage to the nozzle and also the combustion chamber. In the medical application, the high speed liquid injection might be applied for the drug delivery through the skin where the needle is not required anymore. From the above mentioned application, the investigation on the impact pressure of the high speed liquid jet relative to the stand-off distant is significant. The high speed liquid jets are generated by the projectile impact driven method. The high speed projectile is launched by the horizontal single stage powder gun. The experimental study focuses on the stand-off between 1.5 cm to 6.0 cm, while the nozzle contains approximately 1.5cm3 of water in its cavity. The nozzle conical angles are 30° and 60° with the orifice diameter of 0.7 mm. The jet velocities are measured by laser beam interruptions method. The target material is the Polymethyl Methacrylate (PMMA) which the impact pressure is measured by using a piezoelectric Polyvinylidene Fluoride (PVDF) film. From the experiments, the maximum water jet velocity of 2290 m/s can be obtained from the 30° conical angle nozzle. The maximum impact pressures of nozzle conical angle of 30° and 60° are 3.4 GPa and 2.6 GPa respectively, at stand-off distance 3 cm. However, at the stand-off distance more than 3 cm, the impact pressure significantly decreases, because of aerodynamic drag, jets core break-up, and atomization of the water.

  17. Illinois Team Advances Resolution of E-Jet Printing Staff --Semiconductor International, 9/6/2007 2:40:00 PM

    E-print Network

    Rogers, John A.

    Illinois Team Advances Resolution of E-Jet Printing Staff -- Semiconductor International, 9 that they have improved e-jet printing, which is used to create large-area circuits, displays and photovoltaic printing processes can produce "functional devices that establish new resolution benchmarks for liquid

  18. A new approach to deep desulfurization of gasoline, diesel fuel and jet fuel by selective adsorption for ultra-clean fuels and for fuel cell applications

    Microsoft Academic Search

    Xiaoliang Ma; Lu Sun; Chunshan Song

    2002-01-01

    In order to further reduce the sulfur content in liquid hydrocarbon fuels (gasoline, diesel fuel and jet fuel) for producing ultra-clean transportation fuels and for fuel cell applications, we explored a new desulfurization process by selective adsorption for removing sulfur (SARS). An adsorbent was developed and used for adsorption desulfurization of diesel fuel, gasoline and jet fuel at room temperature.

  19. Mystery Liquids

    NSDL National Science Digital Library

    PBS

    2012-01-01

    In this math lesson, learners analyze the density of liquids in order to explore linear functions. Learners gather mass and volume data for two mystery liquids, oil and water, and then use the data to explore linear functions. Learners discuss the physical meaning of the slopes and y-intercepts of the various lines they create from scatterplots.

  20. Jam Jar Jet

    NSDL National Science Digital Library

    2014-10-14

    In this activity, learners create a "Jam Jar Jet" based on Francois Reynst's discovery of a pulsejet engine, which uses one opening for both air intake and exhaust. Learners will be amazed at the deep blue, noisy flame that grows and shrinks and "breathes" fire in the jar. Learners can add salt or boric acid crystals to change the color of the flames. Use this activity to explore combustion and/or aerospace engineering. This resource includes step by step instructions with helpful photographs, trouble-shooting tips, and resources. This is an advanced project that should only be undertaken with appropriate safety precautions. Follow all directions carefully.

  1. Hadron jets in perspective

    SciTech Connect

    Quigg, C.

    1982-11-01

    The subject of hadron jet studies, to judge by the work presented at this workshop, is a maturing field which is still gathering steam. The very detailed work being done in lepton-lepton and lepton-hadron collisions, the second-generation measurements being carried out at Fermilab, the CERN SPS, and the ISR, and the very high energy hard scatterings being observed at the CERN Collider all show enormous promise for increased understanding. Perhaps we shall yet reach that long-sought nirvana in which high-p/sub perpendicular/ collisions become truly simple.

  2. Lear jet telescope system

    NASA Technical Reports Server (NTRS)

    Erickson, E. F.; Goorvitch, D.; Dix, M. G.; Hitchman, M. J.

    1974-01-01

    The telescope system was designed as a multi-user facility for observations of celestial objects at infrared wavelengths, where ground-based observations are difficult or impossible due to the effects of telluric atmospheric absorption. The telescope is mounted in a Lear jet model 24B which typically permits 70 min. of observing per flight at altitudes in excess of 45,000 ft (13 km). Telescope system installation is discussed, along with appropriate setup and adjustment procedures. Operation of the guidance system is also explained, and checklists are provided which pertain to the recommended safe operating and in-flight trouble-shooting procedures for the equipment.

  3. Liquid pearls

    E-print Network

    Bremond, Nicolas; Bibette, Jérôme

    2010-01-01

    This fluid dynamics video reports how to form liquid core capsules having a thin hydrogel elastic membrane named liquid pearls. These fish-egg like structures are initially made of a millimetric liquid drop, aqueous or not, coated with an aqueous liquid film containing sodium alginate that gels once the double drop enters a calcium chloride bath. The creation of such pearls with micrometer thick membrane requires to suppress mixing until gelling takes place. Here, we show that superimposing a two dimensional surfactant precipitation at the interface confers a transient rigidity that can damp the shear induced instability at impact. Based on this, pearls containing almost any type of liquids can be created. The video focuses on the dynamics of the entry of the compound drop into the gelling bath.

  4. 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)

    Mueller, Andreas G.

    2015-02-01

    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.

  5. Jet Propulsion Laboratory Introduction 1

    E-print Network

    Waliser, Duane E.

    for the period January 1 through December 31, 1989. JET PROPULSION LABORATORY California Institute of TechnologyJPL Annual Report 1989 Jet Propulsion Laboratory #12;#12;CONTENTS Introduction 1 Director's Message 2 Flight Projects 5 Space and Earth Science 15 Advanced Technology 22 Telecommunications Systems 31

  6. LIFTED LAMINAR JET DIFFUSION FLAMES

    Microsoft Academic Search

    AMABLE LIÑÁN; EDUARDO FERNÁNDEZ-TARRAZO; MARCOS VERA; ANTONIO L. SÁNCHEZ

    2005-01-01

    This paper addresses the numerical description of lifted flames in axisymmetric laminar coflow jets. The analysis considers moderately large values of the Reynolds number, when the boundary-layer approximation can be used to describe the slender mixing region that extends between the jet exit and the flame, providing the profiles of velocity and mixture fraction that exist immediately upstream from the

  7. Mercury Jet Studies Tristan Davenne

    E-print Network

    McDonald, Kirk

    Mercury Jet Studies Tristan Davenne Rutherford Appleton Laboratory Joint UKNF, INO, UKIERI meeting mercury target and reported a radial velocity at surface of mercury jet due to proton beam is 36m/s #12;Numerical simulation of Sievers & Pugnat Result Click on image above to watch video of 2cm mercury target

  8. Magnetic Field Topology in Jets

    NASA Technical Reports Server (NTRS)

    Gardiner, T. A.; Frank, A.

    2000-01-01

    We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.

  9. OPENING ANGLES OF COLLAPSAR JETS

    SciTech Connect

    Mizuta, Akira; Ioka, Kunihito [Theory Center, Institute of Particle and Nuclear Studies, KEK, Tsukuba 305-0801 (Japan)

    2013-11-10

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by ?{sub j} ? 1/5?{sub 0} and infer the initial Lorentz factor of the jet at the central engine, ?{sub 0}, is a few for existing observations of ?{sub j}. The jet keeps the Lorentz factor low inside the star by converging cylindrically via collimation shocks under the cocoon pressure and accelerates at jet breakout before the free expansion to a hollow-cone structure. In this new picture, the GRB duration is determined by the sound crossing time of the cocoon, after which the opening angle widens, reducing the apparent luminosity. Some bursts violating the maximum opening angle ?{sub j,{sub max}} ? 1/5 ? 12° imply the existence of a baryon-rich sheath or a long-acting jet. We can explain the slopes in both Amati and Yonetoku spectral relations using an off-centered photosphere model, if we make only one assumption that the total jet luminosity is proportional to the initial Lorentz factor of the jet. We also numerically calibrate the pre-breakout model (Bromberg et al.) for later use.

  10. System identification of jet engines

    Microsoft Academic Search

    N. Sugiyama

    2000-01-01

    System identification plays an important role in advanced control systems for jet engines, in which controls are performed adaptively using data from the actual engine and the identified engine. An identification technique for jet engine using the Constant Gain Extended Kalman Filter (CGEKF) is described. The filter is constructed for a two-spool turbofan engine. The CGEKF filter developed here can

  11. Experimental investigation of turbulent wall jet

    NASA Astrophysics Data System (ADS)

    Andre, Matthieu A.; Bardet, Philippe M.

    2011-11-01

    Water jet flowing on a flat plate surrounded by quiescent air constitutes a standard case for the study of the interaction between turbulence and the liquid-air interface. This is of particular interest in the understanding of heat and mass transfers across interfaces. The structure of the surface has a great influence on the rate of the transfers which is critical for chemical processes like separation or absorption; pool-type nuclear reactor; climate modeling etc. This study focuses on high Froude (8 to 12) and Weber (3300 to 7400) numbers at which the surface exhibits small wavelength and large amplitude deformations, such as ligaments, surface break up with air entrainment and droplets projection. The experiment features a high velocity (up to 7.5 m/s) water wall jet (19.05mm thick at the nozzle exit) flowing on a flat plate (Re=10^5 to 1.5.10^5). High speed movies and PLIF visualization show the evolution of the surface from smooth to 2D structures, then 3D disturbances as the turbulence arising from the wall interacts with the surface.

  12. Noise from the fine scale turbulence of jets in forward flight, nonaxisymmetric jets and installed jets

    NASA Astrophysics Data System (ADS)

    Pastouchenko, Nikolai N.

    It is known experimentally that a jet in forward flight radiates less noise than the same jet in a static environment. At a forward flight Mach number of 0.2, the noise reduction, depending on the jet operating conditions, could be as large as 4--5 dB in the sideline directions. In the past, a way to predict flight effects was to use the method of relative velocity exponent. Another method was to extrapolate measured static jet noise to the flight condition by means of scaling formulas. Both methods are semi-empirical. The fine scale turbulence jet mixing noise theory of Tam and Auriault (AIAA Journal, Vol. 37, No.2, pp. 145--153, 1999) is extended for applications to jets in forward flight. The effect of forward flight on the sources of fine scale turbulent jet mixing noise is also investigated. The noise from the fine scale turbulence of high speed nonaxisymmetric jets is considered. A prediction method is developed by extending the work of Tam and Auriault. A set of improved numerical boundary conditions for use in nonaxisymmetric jet mean flow and turbulence calculations is developed. It is known that nonaxisymmetric mean flow has a significant impact on the radiated noise spectrum and directivity through refraction. In the Tam and Auriault theory, this effect is accounted for by means of the adjoint Green's function. Here the adjoint Green's function method is extended to nonaxisymmetric flows. Extensive comparisons between calculated and experimentally measured jet noise spectra are presented. Good agreements are found. The noise from a jet installed under a wing of an aircraft is considered. A computational model for prediction of the radiated noise of the installed jet is developed. The parabolized Reynolds Averaged Navier-Stokes (RANS) equations supplemented by the k - epsilon model developed by Thies and Tam (AIAA Journal, Vol. 34, No.2, pp. 309--316, 1996) are modified and reformulated to compute the installed jet turbulent jet flow. The adjoint Green's function approach is extended to installed jets to include the flow effect and reflection from the wing.

  13. Simulation of Rotating Continuous Casting of Steel: Thermo-hydrodynamics and Particles Motion

    E-print Network

    Boyer, Edmond

    Simulation of Rotating Continuous Casting of Steel: Thermo-hydrodynamics and Particles Motion Gr CNRS 7635, Sophia Antipolis, France APERAM IMPHY, Imphy, France Abstract In Rotating Continuous Casting is fed by a liquid steel free plunging jet. A numerical model- ling of the RCC has been developed

  14. Laboratory simulations of astrophysical jets

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergey V.; Suzuki-Vidal, Francisco; Ciardi, Andrea; Bocchi, Matteo; Bland, Simon N.; Burdiak, Guy; Chittenden, Jerry P.; de Grouchy, Phil; Hall, Gareth N.; Harvey-Thompson, Adam; Marocchino, Alberto; Swalding, George; Frank, Adam; Blackman, Eric G.; Camenzind, Max

    2011-06-01

    Collimated outflows (jets) are ubiquitous in the universe, appearing around sources as diverse as protostars and extragalactic supermassive black holes. Jets are thought to be magnetically collimated, and launched from a magnetized accretion disk surrounding a compact gravitating object. We have developed the first laboratory experiment to address time-dependent, episodic phenomena relevant to the poorly understood jet acceleration and collimation region (Ciardi et al., 2009). The experiments were performed on the MAGPIE pulsed power facility (1.5 MA, 250 ns) at Imperial College. The experimental results show the periodic ejections of magnetic bubbles naturally evolving into a heterogeneous jet propagating inside a channel made of self-collimated magnetic cavities. The results provide a unique view of the possible transition from a relatively steady-state jet launching to the observed highly structured outflows.

  15. Latest jet results from Tevatron

    SciTech Connect

    Messina, Andrea

    2006-05-01

    This contribution reports preliminary jet results in p{bar p} collisions at {radical}s = 1.96 TeV from the CDF and D0 experiments. The jet inclusive cross section, measured using both the Midpoint and the K{sub T} jet clustering algorithm, is compared to next-to-leading order QCD prediction in different rapidity regions. The b-jet inclusive cross section measured exploiting the long lifetime and large mass of B hadrons is presented and compared to QCD prediction. A complementary measurement, using the large branching fraction of B hadrons into muons, is also described. The measurement of two-particle momentum correlation in jets is presented and compared to predictions.

  16. Nucleosynthesis in Jets from Collapsars

    SciTech Connect

    Fujimoto, Shin-ichiro [Department of Electronic Control, Kumamoto National College of Technology, Kumamoto 861-1102 (Japan); Nishimura, Nobuya; Hashimoto, Masa-aki [Department of Physics, School of Sciences, Kyushu University, Fukuoka 810-8560 (Japan)

    2008-05-21

    We investigate nucleosynthesis inside magnetically driven jets ejected from collapsars, or rotating magnetized stars collapsing to a black hole, based on two-dimensional magnetohydrodynamic simulation of the collapsars during the core collapse. We follow the evolution of the abundances of about 4000 nuclides from the collapse phase to the ejection phase using a large nuclear reaction network. We find that the r-process successfully operates only in the energetic jets (>10{sup 51} erg), so that U and Th are synthesized abundantly, even when the collapsars have a relatively small magnetic field (10{sup 10} G) and a moderately rotating core before the collapse. The abundance patterns inside the jets are similar to that of the r-elements in the solar system. The higher energy jets have larger amounts of {sup 56}Ni. Less energetic jets, which have small amounts of {sup 56}Ni, could induce GRB without supernova, such as GRB060505 and GRB060614.

  17. Magnetically powered jets

    NASA Astrophysics Data System (ADS)

    Spruit, H. C.

    2011-09-01

    This is an update on a previous, more extended conference review text [61], with emphasis on outstanding problem areas. The role of dissipation of magnetic energy in accelerating the flow is discussed, and its importance for explaining high Lorentz factors. The transition between disk and outflow is one of the least understood parts of the magnetic theory; its role in setting the mass flux in the wind, in possible modulations of the mass flux, and the problems in treating it realistically are discussed. Current views on most of these problems are still strongly influenced by the restriction to 2 dimensions (axisymmetry) in previous analytical and numerical work; 3-D effects likely to be important are suggested. An interesting problem area is the nature and origin of the strong, preferably highly ordered magnetic fields known to work best for jet production. The presence or absence of such fields may well be the `second parameter' governing not only the presence of jets but also the X-ray spectra and timing behavior of X-ray binaries.

  18. ICLASS 2009, 11th Triennial International Annual Conference on Liquid Atomization and Spray Systems, Vail, Colorado USA, July 2009

    E-print Network

    Aguilar, Guillermo

    spray cooling [12-14]. The use of low boiling point liquids such as refrigerants or cryogens in sprayICLASS 2009, 11th Triennial International Annual Conference on Liquid Atomization and Spray Systems USA Abstract Flashing or thermodynamic breakup of a liquid jets occurs when a pressurized, subcooled

  19. Jet energy scale and its uncertainty for jets reconstructed using the ATLAS heavy ion jet algorithm

    E-print Network

    The ATLAS collaboration

    2015-01-01

    The jet energy scale (JES) and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC, reconstructed using techniques developed for jet measurements for heavy ion (HI) collisions. The JES is constructed by calibrating the HI jets with respect to the standard jets using the analysis of proton-proton pp collision data. The latter have a well-defined calibration procedure and uncertainty that includes input from various data-driven studies. The calibration of the HI jets is performed using sqrt(s)=8 TeV pp data recorded in 2012 where the performance of the standard jets is well understood. A procedure to adapt the HI JES and its uncertainty to different data samples recorded by ATLAS including pp collisions at sqrt(s)=2.76 TeV, Pb+Pb collisions at sqrt(s_NN)=2.76 TeV and p+Pb collisions at sqrt(s_NN)=5.02 TeV is presented. Finally, the energy scale for jets affected by quenching is studied using Monte Carlo and the uncertainties on the JES obtained from this procedure are ...

  20. Exploring Liquids

    NSDL National Science Digital Library

    Sharon Janulaw

    2010-01-01

    Young learners investigate and observe the properties of three liquids -- water, vegetable oil, and corn syrup. They use their senses to collect data and ask and answer questions. This lesson for young learners introduces the scientific process.

  1. Performance of jets at CMS

    NASA Astrophysics Data System (ADS)

    Schröder, Matthias; CMS collaboration

    2015-02-01

    The calibration and reconstruction of jets critically relies on the performance of the calorimeters. Extending out to large pseudorapidities, the measurements depend on the interplay between forward calorimeters, central calorimeters, and the tracking system. The high number of additional pile-up interactions poses further complications. In CMS, these difficulties are overcome using the 'particle-flow' approach, which aims at reconstructing individually each particle in the event prior to the jet clustering. Measurements of the jet energy scale and the procedure for jet energy calibration in CMS are reviewed, which are performed with dijet, photon + jet, and Z+jet data collected in proton-proton collisions at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.6 fb?1. The effect of pile-up interactions and the state of the art mitigation techniques used in CMS as well as the main sources of uncertainty of the jet energy calibration are also presented.

  2. Line liquids

    Microsoft Academic Search

    David R. Nelson

    1991-01-01

    We review the long wavelength description of three-dimensional liquids of entangled lines with an average orientation along the z-axis. Originally developed for polymer nematics, a closely related approach is applicable to the vortex liquid state of high temperature superconductors, and to ferro- and electrorheological fluids. The theory predicts unusual behavior of the three-dimensional structure function near the origin of reciprocal

  3. Ionic Liquids

    Microsoft Academic Search

    J. D. Holbrey; K. R. Seddon

    1999-01-01

    Ionic liquids are receiving an upsurge of interest as green solvents; primarily as replacements for conventional media in\\u000a chemical processes. This review presents an overview of the chemistry that has been developed utilising ionic liquids as either\\u000a catalyst and\\/or solvent, with particular emphasis on processes that have been taken beyond the pre-competetive laboratory\\u000a stage and represent clean industrial technology with

  4. Jet Simulation in a Diesel Engine

    Microsoft Academic Search

    Zhiliang Xu

    2005-01-01

    We present a numerical study of the jet breakup and spray formation in a diesel engine by the Front Tracking method. The mechanisms of jet breakup and spray formation of a high speed diesel jet injected through a circular nozzle are the key to design a fuel efficient, nonpolluting diesel engine. We conduct the simulations for the jet breakup within

  5. Surface evolution models in abrasive jet micromachining

    Microsoft Academic Search

    A. Ghobeity; T. Krajac; T. Burzynski; M. Papini; J. K. Spelt

    2008-01-01

    The paper presents model predictions and experimental data related to the abrasive jet micromachining of masked and unmasked channels in glass. The spatial and velocity distributions of particles in the jet of an abrasive jet micromachining (AJM) setup were measured using a novel technique. It was found that the velocity decreased linearly from the centerline of the jet to the

  6. 30 CFR 56.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 2010-07-01 false Jet drills. 56.7801 Section 56.7801 Mineral Resources...Piercing Rotary Jet Piercing § 56.7801 Jet drills. Jet piercing drills shall be provided with— (a) A system to...

  7. 30 CFR 57.7801 - Jet drills.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2010-07-01 2010-07-01 false Jet drills. 57.7801 Section 57.7801 Mineral Resources...Rotary Jet Piercing-Surface Only § 57.7801 Jet drills. Jet piercing drills shall be provided with: (a) A system to...

  8. Jet mixer noise suppressor using acoustic feedback

    NASA Technical Reports Server (NTRS)

    Rice, Edward J. (inventor)

    1995-01-01

    The present invention generally relates to providing an improved jet mixer noise suppressor for high speed jets that rapidly mixes high speed air flow with a lower speed air flow, and more particularly, relates to an improved jet mixer noise suppressor that uses feedback of acoustic waves produced by the interaction of shear flow instability waves with an obstacle downstream of the jet nozzle.

  9. Jet mixer noise suppressor using acoustic feedback

    NASA Technical Reports Server (NTRS)

    Rice, Edward J. (Inventor)

    1994-01-01

    The present invention generally relates to providing an improved jet mixer noise suppressor for high speed jets that rapidly mixes high speed air flow with a lower speed air flow, and more particularly, relates to an improved jet mixer noise suppressor that uses feedback of acoustic waves produced by the interaction of sheer flow instability waves with an obstacle downstream of the jet nozzle.

  10. Numerical simulation of jet noise

    NASA Astrophysics Data System (ADS)

    Paliath, Umesh

    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 nozzle internal and external flows as well as the jet plume. This methodology allows the turbulence model to transition from an unsteady Reynolds Averaged Navier-Stokes (URANS) method for attached boundary layers to a Large Eddy Simulation (LES) in separated regions. Thus, it is ideally suited to jet flow simulations where the nozzle is included. Both cylindrical polar and Cartesian coordinate systems are used. A spectral method is used to avoid the centerline singularity when using the cylindrical coordinate system. The one equation Spalart-Allmaras turbulence model, in DES mode, is used to describe the evolution of the turbulent eddy viscosity. An explicit 4th order Runge-Kutta time marching scheme is used. For spatial discritization the Dispersion Relation Preserving scheme(DRP) is used. The farfield sound is evaluated using the Ffowcs Williams-Hawkings permeable surface wave extrapolation method. This permits the noise to be predicted at large distances from the jet based on fluctuations in the jets near field. The present work includes a study of the effect of different nozzle geometries such as axisymmetric/non-axisymmetric and planar/non-planar exits on the far field noise predictions. Also the effect of operating conditions such as a heated/unheated jet, the effect of forward flight, a jet flow at an angle of attack, and the effect of a supersonic exit Mach number, are included in the study.

  11. Multiple jet interactions

    E-print Network

    Hehr, Roger James

    1983-01-01

    Type Designation Key Direction of Traverse: A - Axial R ? Radial A CON1 N (1) (3) (2) (2) Probe Type: N - Straight, a=O' S - Slant, a=45' (3) Configuration: CON1 CON2 CON3 CON4 CONS CON6 Jets h/D X/h 8 5. 0 16 2. 5 5. 33 7. 5 8 5. 0... of Mean Velocity At x/D=4 D, 5D (configuration 2). . . 33 0. 30 SYM INFORMATION: ta RUN 02 ACON1N X/0 40 8 RUN 06 RCON1N X/O 40 ROOI (1974) Canv. X/0 62 V ROOI (1974) New X/0 62 0. 25 0. 20 0. 10 0. 05 0. 00 0. 00 0. 04 0. 06 0. 12 0. 16 0. 20...

  12. Water cooled steam jet

    DOEpatents

    Wagner, Jr., Edward P. (Idaho Falls, ID)

    1999-01-01

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed therebetween. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock.

  13. Optical emission from jets

    NASA Astrophysics Data System (ADS)

    Miley, G.

    Knots, hot spots, and boundaries of radio sources are regarded as the interface of jets with their surroundings in a discussion of several recently found morphological associations between extended radio emission and optical emission lines. These line/radio associations are seen in both radio and Seyfert galaxies, usually just outside bright radio regions and close to bends in the radio sources. Two radio galaxies with extended associations are considered: 3C305, and Coma A (3C277.3), which is remarkable for the strong similarity of its H-alpha emission map to the radio morphology. Several interpretations of the measured velocities in the extranuclear emission line gas, dependent on the origin of the gas, are discussed. In conclusion, it is proposed that broad-line regions may be intimately associated with the parsec-scale flat spectrum radio cores.

  14. Commercial jet transport crashworthiness

    NASA Technical Reports Server (NTRS)

    Widmayer, E.; Brende, O. B.

    1982-01-01

    The results of a study to identify areas of research and approaches that may result in improved occupant survivability and crashworthiness of transport aircraft are given. The study defines areas of structural crashworthiness for transport aircraft which might form the basis for a research program. A 10-year research and development program to improve the structural impact resistance of general aviation and commercial jet transport aircraft is planned. As part of this program parallel studies were conducted to review the accident experience of commercial transport aircraft, assess the accident performance of structural components and the status of impact resistance technology, and recommend areas of research and development for that 10-year plan. The results of that study are also given.

  15. NASA's Jet Propulsion Laboratory

    NSDL National Science Digital Library

    This rich and extensive site from the California Institutes of Technology's Jet Propulsion Laboratory leads users to a vast array of images, videos and resources related to aerospace exploration and technology. Of especial interest to educators will be the Images and Multimedia sections of the site. The images tab takes users to the Planetary Photojournal section which provides access to thousands of photographs of planets (as well as their satellites), asteroids, and comets. In the multimedia section users can view slideshows, listen to podcasts and watch videos which explore a range of topics from the rainbow colors of Saturn to NASA's Spitzer Space Telescope. Resources on the site are free to use and could be integrated into a variety of curriculum.

  16. Micromachined chemical jet dispenser

    DOEpatents

    Swierkowski, Steve P. (Livermore, CA)

    1999-03-02

    A dispenser for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 .mu.m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (.about.200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments.

  17. Micromachined chemical jet dispenser

    DOEpatents

    Swierkowski, S.P.

    1999-03-02

    A dispenser is disclosed for chemical fluid samples that need to be precisely ejected in size, location, and time. The dispenser is a micro-electro-mechanical systems (MEMS) device fabricated in a bonded silicon wafer and a substrate, such as glass or silicon, using integrated circuit-like fabrication technology which is amenable to mass production. The dispensing is actuated by ultrasonic transducers that efficiently produce a pressure wave in capillaries that contain the chemicals. The 10-200 {micro}m diameter capillaries can be arranged to focus in one spot or may be arranged in a larger dense linear array (ca. 200 capillaries). The dispenser is analogous to some ink jet print heads for computer printers but the fluid is not heated, thus not damaging certain samples. Major applications are in biological sample handling and in analytical chemical procedures such as environmental sample analysis, medical lab analysis, or molecular biology chemistry experiments. 4 figs.

  18. Calorimetry Optimised for Jets

    NASA Astrophysics Data System (ADS)

    Videau, Henri; Brient, Jean-Claude

    2002-01-01

    The physics programme for a coming electron linear collider is dominated by events with final states containing many jets, dijets from H, W, Z. We contend that, in the energy range under consideration, the best approach is to optimise the independent measurement of the tracks in the tracker, the photons in the electromagnetic calorimeter and the neutral hadrons in the calorimetry, together with a good lepton identification. This can be achieved with a good tracker and a high granularity calorimetry providing particle separation, through an efficient energy flow algorithm. But we do not contend that this is a universal panacea. Following that programme from the calorimetric side on hardware and software issues is the goal of the CALICE collaboration.

  19. Water cooled steam jet

    DOEpatents

    Wagner, E.P. Jr.

    1999-01-12

    A water cooled steam jet for transferring fluid and preventing vapor lock, or vaporization of the fluid being transferred, has a venturi nozzle and a cooling jacket. The venturi nozzle produces a high velocity flow which creates a vacuum to draw fluid from a source of fluid. The venturi nozzle has a converging section connected to a source of steam, a diffuser section attached to an outlet and a throat portion disposed there between. The cooling jacket surrounds the venturi nozzle and a suction tube through which the fluid is being drawn into the venturi nozzle. Coolant flows through the cooling jacket. The cooling jacket dissipates heat generated by the venturi nozzle to prevent vapor lock. 2 figs.

  20. Design and Development of an Apparatus to Study Aviation Jet Fuel Thermal Stability

    NASA Astrophysics Data System (ADS)

    Wong, Owen

    A single tube flow heat exchanger was designed and built to thermally stress Jet A-1 with air-saturated and deoxygenated levels of dissolved oxygen over a range of fuel temperatures, pressures, and flow rates. Liquid samples of thermally degraded Jet A-1 were analyzed using various physical and optical methods to determine which methods were sensitive enough to measure compositional changes in thermally degraded liquid fuel and to correlate these changes to the measured amount of deposits produced. Temperature programmed oxidation (TPO) was shown to be successful in measuring deposit quantity and structure, while UV-visible absorption and UV-visible fluorescence were sensitive enough to quickly measure the relative population growth of large aromatic compounds that lead to deposit formation in thermally stressed Jet A-1.