Interferometric analysis of laboratory photoionized plasmas utilizing supersonic gas jet targets.

NASA Astrophysics Data System (ADS)

Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

2018-06-01

Photoionized plasmas are an important component of active galactic nuclei, x-ray binary systems and other astrophysical objects. Laboratory produced photoionized plasmas have mainly been studied at large scale facilities, due to the need for high intensity broadband x-ray flux. Using supersonic gas jets as targets has allowed university scale pulsed power generators to begin similar research. The two main advantages of this approach with supersonic gas jets include: possibility of a closer location to the x-ray source and no attenuation related to material used for containment and or tamping. Due to these factors, this experimental platform creates a laboratory environment that more closely resembles astrophysical environments. This system was developed at the Nevada Terawatt Facility using the 1 MA pulsed power generator Zebra. Neon, argon, and nitrogen supersonic gas jets are produced approximately 7-8mm from the z-pinch axis. The high intensity broadband x-ray flux produced by the collapse of the z-pinch wire array implosion irradiates the gas jet. Cylindrical wire arrays are made with 4 and 8 gold 10µm thick wire. The z-pinch radiates approximately 12-16kj of x-ray energy, with x-ray photons under 1Kev in energy. The photoionized plasma is measured via x-ray absorption spectroscopy and interferometry. A Mach-Zehnder interferometer is used to the measure neutral density of the jet prior to the zebra shot at a wavelength of 266 nm. A dual channel air-wedge shearing interferometer is used to measure electron density of the ionized gas jet during the shot, at wavelengths of 532nm and 266nm. Using a newly developed interferometric analysis tool, average ionization state maps of the plasma can be calculated. Interferometry for nitrogen and argon show an average ionization state in the range of 3-8. Preliminary x-ray absorption spectroscopy collected show neon absorption lines. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.

Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

PubMed

Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

2016-11-14

We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

Study on the wiping gas jet in continuous galvanizing line

NASA Astrophysics Data System (ADS)

Kweon, Yong-Hun; Kim, Heuy-Dong

2011-09-01

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

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J.; Halpern, B.L.

1994-10-18

A method and apparatus are disclosed for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases. 8 figs.

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, Jerome J.; Halpern, Bret L.

1994-01-01

A method and apparatus for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases.

Optimizing Dense Plasma Focus Neutron Yields With Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Stein, Elizabeth; Higginson, Drew; Kueny, Christopher; Link, Anthony; Schmidt, Andrea

2017-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high-density jets are modeled in the large-eddy Navier-Stokes code CharlesX, which is suitable for modeling both sub-sonic and supersonic gas flow. The gas pattern, which is essentially static on z-pinch time scales, is imported from CharlesX to LSP for neutron yield predictions. Fast gas puffs allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of a subsonic jet increases relative to the background fill, we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density via super-sonic flow (also known as Mach diamonds) allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration and the necessary jet conditions for increasing neutron yield and reducing yield variability are explored. Simulations of realistic jet profiles are performed and compared to the ideal scenario. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

Enceladus' Supersonic Gas Jets' Role in Diurnal Variability of Particle Flux

NASA Astrophysics Data System (ADS)

Hansen, Candice; Esposito, Larry W.; Portyankina, Ganna; Hendrix, Amanda; Colwell, Joshua E.; Aye, Klaus-Michael

2016-10-01

Introduction: The Cassini Ultraviolet Imaging Spectrograph (UVIS) has observed 6 occultations of stars by Enceladus' plume from 2005 to 2011 [1]. Supersonic gas jets were detected, imbedded in the overall expulsion of gas at escape velocity along the tiger stripe fissures that cross Enceladus' south pole [2]. The gas flux can be calculated [1], and is observed to vary just 15% in over 6 years, representing a steady output of ~200 kg/sec. In contrast, the brightness of the particle jets, a proxy for the amount of particles expelled, varies 3x with orbital longitude [3], implicating tidal stresses. This is not necessarily inconsistent with the steady gas flux, which had not been measured at apokrone until now.2016 epsilon Orionis Occultation: In order to investigate whether gas flow increases dramatically at apokrone an occultation observation was inserted into the Cassini tour on March 11, 2016 on orbit 233. Enceladus was at a mean anomaly of 208 at the time of the occultation. Using the same methodology as previously employed the column density has been determined to be 1.5 x 1016 cm-2, giving a gas flux of 250 kg/sec. This value is 20% higher than the average 210 kg/sec, but only 15% higher than the occultations at a mean anomaly of 236; i.e. higher than the others but not by a factor of 2 or 3. The overall expulsion of gas from the south pole of Enceladus thus does not seem to change dramatically with orbital position.Jets: The line of sight to the star pierced the Baghdad I gas jet. The jet data, in contrast to the integrated plume, look significantly different in this dataset. The column density of the jet is higher than observed in previous occultations. The collimation of the jet is more pronounced and from that we derive a mach number of 8-9, compared to a previous value for this jet of 6. We conclude that the higher velocity and increased quantity of gas in the jet close to apokrone indicate that the jets are the primary contributors to the increased

Investigation of the gas-jet ejector in KamAZ trucks

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1984-03-01

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 housing, a Laval nozzle, a front wall with cylindrical neck, a tin-plate diffuser, an air supply pipe, and a flange for attaching the ejector to the flange of the exhaust muffler of the truck. The gas-jet ejectors are driven bymore » the exhaust gas (EG) of the trucks. The dependences of the EG flow rate, fuel expenditure, EG temperature ahead of the ejector, and the rotational frequency of the engine crankshaft on the diameter at different EG pressures. It is recommended that gas-jet ejectors be used on series produced tank trucks instead of rotary vacuum pumps with mechanical drive.« less

The effect of working gas impurities on plasma jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, X. Y.; He, M. B., E-mail: pulhmb@mail.hust.edu.cn; IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240

Air intrusion reduced the purity of working gas inside the tube for plasma jet, and thereby, affected the discharge dynamics. In this paper, the effect of using working gas with different purity level (helium purity 99.99999%, 99.99%, 99.9%, and 99%) on photoionization and the chemical reactivity of plasma jet were studied using a 2 dimensional plasma jet model. Photoionization of air species acted as a source of pre-ionization in front of the ionization region, which facilitated the transition from localized discharge to streamers inside the tube. The density of reactive species inside the tube was found to increase with themore » concentration of working gas impurities. For the highest purity helium (99.99999%), despite a low photoionization rate and the distance between the photoionization region and ionization region inside the tube, by increasing the applied voltage and decreasing the distance between the electrode and nozzle, plasma jets were formed.« less

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

NASA Astrophysics Data System (ADS)

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

2010-02-01

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

STAR FORMATION SUPPRESSION DUE TO JET FEEDBACK IN RADIO GALAXIES WITH SHOCKED WARM MOLECULAR GAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lanz, Lauranne; Ogle, Patrick M.; Appleton, Philip N.

2016-07-20

We present Herschel observations of 22 radio galaxies, selected for the presence of shocked, warm molecular hydrogen emission. We measured and modeled spectral energy distributions in 33 bands from the ultraviolet to the far-infrared to investigate the impact of jet feedback on star formation activity. These galaxies are massive, early-type galaxies with normal gas-to-dust ratios, covering a range of optical and infrared colors. We find that the star formation rate (SFR) is suppressed by a factor of ∼3–6, depending on how molecular gas mass is estimated. We suggest that this suppression is due to the shocks driven by the radiomore » jets injecting turbulence into the interstellar medium (ISM), which also powers the luminous warm H{sub 2} line emission. Approximately 25% of the sample shows suppression by more than a factor of 10. However, the degree of SFR suppression does not correlate with indicators of jet feedback including jet power, diffuse X-ray emission, or intensity of warm molecular H{sub 2} emission, suggesting that while injected turbulence likely impacts star formation, the process is not purely parameterized by the amount of mechanical energy dissipated into the ISM. Radio galaxies with shocked warm molecular gas cover a wide range in SFR–stellar mass space, indicating that these galaxies are in a variety of evolutionary states, from actively star-forming and gas-rich to quiescent and gas-poor. SFR suppression appears to have the largest impact on the evolution of galaxies that are moderately gas-rich.« less

Exhaust-gas measurements from NASAs HYMETS arc jet.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Paul Albert

Arc-jet wind tunnels produce conditions simulating high-altitude hypersonic flight such as occurs upon entry of space craft into planetary atmospheres. They have traditionally been used to study flight in Earth's atmosphere, which consists mostly of nitrogen and oxygen. NASA is presently using arc jets to study entry into Mars' atmosphere, which consists of carbon dioxide and nitrogen. In both cases, a wide variety of chemical reactions take place among the gas constituents and with test articles placed in the flow. In support of those studies, we made measurements using a residual gas analyzer (RGA) that sampled the exhaust stream ofmore » a NASA arc jet. The experiments were conducted at the HYMETS arc jet (Hypersonic Materials Environmental Test System) located at the NASA Langley Research Center, Hampton, VA. This report describes our RGA measurements, which are intended to be used for model validation in combination with similar measurements on other systems.« less

Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

2016-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Method for microwave plasma assisted supersonic gas jet deposition of thin films

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1994-10-18

A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets. 5 figs.

Method for microwave plasma assisted supersonic gas jet deposition of thin films

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1994-01-01

A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets.

Propagation of gas jet in liquid

NASA Astrophysics Data System (ADS)

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

1984-07-01

A comprehensive experimental study was made of discharge of a gas jet from an orifice and its evolution in a liquid medium. Nitrogen, air, helium, chlorine, carbon dioxide, hydrogen chloride, ammonia, and water vapor superheated to 200 to 250 C were discharged vertically up, vertically down, or laterally into water at 18 to 100 C as well as into aqueous solutions of KOH and NaOH, under pressures varied from hydrostatic to 41x10(5) Pa. They were discharged through sonic cylindrical, conical nozzles and supersonic leLaval, axisymmetric, flat nozzles with orifices 2 to 50 mm wide. The discharge velocity varied from 2 to 1000 m/s and the jet underexpansion ratio varied from 1 to 20. The study has yielded data on the mechanisms of gas-liquid interaction, structure and dynamics of the interaction space, and dependence of those on the discharge conditions and on the degree of gas assimilation. Experiments were performed in both continuous and pulse modes, the latter for a study of transients and back shocks.

Thin film deposition using rarefied gas jet

NASA Astrophysics Data System (ADS)

Pradhan, Sahadev, , Dr.

2017-01-01

The rarefied gas jet of aluminium is studied at Mach number Ma =(U_j /√{ kbTj / m }) in the range .01 jet velocity and temperature, n_d is the number density of the jet, m and d are the molecular mass and diameter, and kb is the Boltzmann constant. An important finding is that the capture width (cross-section of the gas jet deposited on the substrate) is symmetric around the centerline of the substrate, and decreases with increased Mach number due to an increase in the momentum of the gas molecules. DSMC simulation results reveals that at low Knudsen number ((Kn =0.01); shorter mean free paths), the atoms experience more collisions, which direct them toward the substrate. However, the atoms also move with lower momentum at low Mach number ,which allows scattering collisions to rapidly direct the atoms to the substrate.

Gas dynamics of a supersonic radial jet. Part I

NASA Astrophysics Data System (ADS)

Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.; Kundasev, S. G.

2015-11-01

The gas dynamics of a supersonic radial jet was studied under conditions close to cold spraying. The jet visualization was performed for exhaustion into submerged space with atmospheric pressure and jet impingement to a target. For the cases of swirled and unswirled supersonic radial jets, the pressure profiles measured by a Pitot tube were taken for different distances from the nozzle outlet and for different widths of supersonic part δ ex = 0.5-2 mm and for prechamber pressure in the range p 0 = 1-2.5 MPa.

Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

NASA Astrophysics Data System (ADS)

Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

2017-09-01

Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

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

NASA Astrophysics Data System (ADS)

Surov, V. S.

1993-02-01

The motion of a liquid drop (jet) and of the ambient gas is described, in the general case, by Navier-Stokes equations. An approximate solution to the interaction of a plane shock wave with a single liquid drop is presented. Based on the analysis, the general system of Navier-Stokes equations is reduced to two groups of equations, Euler equations for gas and Navier-Stokes equations for liquid; solutions to these equations are presented. The discussion also covers the modeling of the interaction of a shock wave with a drop screen, interaction of a liquid jet with a counterpropagating supersonic gas flow, and modeling of processes in a shock layer during the impact of a drop against an obstacle in gas flow.

Active Control of Jets in Cross-Flow for Film Cooling Applications

NASA Technical Reports Server (NTRS)

Nikitopoulos, Dimitris E.

2003-01-01

Jets in cross-flow have applications in film cooling of gas turbine vanes, blades and combustor liners. Their cooling effectiveness depends on the extent to which the cool jet-fluid adheres to the cooled component surface. Lift-off of the cooling jet flow or other mechanisms promoting mixing, cause loss of cooling effectiveness as they allow the hot "free-stream" fluid to come in contact with the component surface. The premise of this project is that cooling effectiveness can be improved by actively controlling (e.9. forcing, pulsing) the jet flow. Active control can be applied to prevent/delay lift-off and suppress mixing. Furthermore, an actively controlled film-cooling system coupled with appropriate sensory input (e.g. temperature or heat flux) can adapt to spatial and temporal variations of the hot-gas path. Thus, it is conceivable that the efficiency of film-cooling systems can be improved, resulting in coolant fluid economy. It is envisioned that Micro Electro-Mechanical Systems (MEMS) will play a role in the realization of such systems. As a first step, a feasibility study will be conducted to evaluate the concept, identify actuation and sensory elements and develop a control strategy. Part of this study will be the design of a proof-of-concept experiment and collection of necessary data.

Analysis of gas jetting and fumarole acoustics at Aso Volcano, Japan

DOE PAGES

McKee, Kathleen; Fee, David; Yokoo, Akihiko; ...

2017-03-30

The gas-thrust region of a large volcanic eruption column is predominately a momentum-driven, fluid flow process that perturbs the atmosphere and produces sound akin to noise from jet and rocket engines, termed “jet noise”. In this paper, we aim to enhance understanding of large-scale volcanic jets by studying an accessible, less hazardous fumarolic jet. We characterize the acoustic signature of ~ 2.5-meter wide vigorously jetting fumarole at Aso Volcano, Japan using a 5-element infrasound array located on the nearby crater. The fumarole opened on 13 July 2015 on the southwest flank of the partially collapsed pyroclastic cone within Aso Volcano'smore » Naka-dake crater and had persistent gas jetting, which produced significant audible jet noise. The array was ~ 220 m from the fumarole and 57.6° from the vertical jet axis, a recording angle not typically feasible in volcanic environments. Array processing is performed to distinguish fumarolic jet noise from wind. Highly correlated periods are characterized by sustained, low-amplitude signal with a 7–10 Hz spectral peak. Finite difference time domain method numerical modeling suggests the influence of topography near the vent and along the propagation path significantly affects the spectral content, complicating comparisons with laboratory jet noise. The fumarolic jet has a low estimated Mach number (0.3 to 0.4) and measured temperature of ~ 260 °C. The Strouhal number for infrasound from volcanic jet flows and geysers is not known; thus we assume a peak Strouhal number of 0.19 based on pure-air laboratory jet experiments. This assumption leads to an estimated exit velocity of the fumarole of ~ 79 to 132 m/s. Finally, using published gas composition data from 2003 to 2009, the fumarolic vent area estimated from thermal infrared images, and estimated jet velocity, we estimate total volatile flux at ~ 160–270 kg/s (14,000–23,000 t/d).« less

Analysis of gas jetting and fumarole acoustics at Aso Volcano, Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKee, Kathleen; Fee, David; Yokoo, Akihiko

The gas-thrust region of a large volcanic eruption column is predominately a momentum-driven, fluid flow process that perturbs the atmosphere and produces sound akin to noise from jet and rocket engines, termed “jet noise”. In this paper, we aim to enhance understanding of large-scale volcanic jets by studying an accessible, less hazardous fumarolic jet. We characterize the acoustic signature of ~ 2.5-meter wide vigorously jetting fumarole at Aso Volcano, Japan using a 5-element infrasound array located on the nearby crater. The fumarole opened on 13 July 2015 on the southwest flank of the partially collapsed pyroclastic cone within Aso Volcano'smore » Naka-dake crater and had persistent gas jetting, which produced significant audible jet noise. The array was ~ 220 m from the fumarole and 57.6° from the vertical jet axis, a recording angle not typically feasible in volcanic environments. Array processing is performed to distinguish fumarolic jet noise from wind. Highly correlated periods are characterized by sustained, low-amplitude signal with a 7–10 Hz spectral peak. Finite difference time domain method numerical modeling suggests the influence of topography near the vent and along the propagation path significantly affects the spectral content, complicating comparisons with laboratory jet noise. The fumarolic jet has a low estimated Mach number (0.3 to 0.4) and measured temperature of ~ 260 °C. The Strouhal number for infrasound from volcanic jet flows and geysers is not known; thus we assume a peak Strouhal number of 0.19 based on pure-air laboratory jet experiments. This assumption leads to an estimated exit velocity of the fumarole of ~ 79 to 132 m/s. Finally, using published gas composition data from 2003 to 2009, the fumarolic vent area estimated from thermal infrared images, and estimated jet velocity, we estimate total volatile flux at ~ 160–270 kg/s (14,000–23,000 t/d).« less

Macroscopic analysis of gas-jet wiping: Numerical simulation and experimental approach

NASA Astrophysics Data System (ADS)

Lacanette, Delphine; Gosset, Anne; Vincent, Stéphane; Buchlin, Jean-Marie; Arquis, Éric

2006-04-01

Coating techniques are frequently used in industrial processes such as paper manufacturing, wire sleeving, and in the iron and steel industry. Depending on the application considered, the thickness of the resulting substrate is controlled by mechanical (scraper), electromagnetic (if the entrained fluid is appropriated), or hydrodynamic (gas-jet wiping) operations. This paper deals with the latter process, referred to as gas-jet wiping, in which a turbulent slot jet is used to wipe the coating film dragged by a moving substrate. This mechanism relies on the gas-jet-liquid film interaction taking place on the moving surface. The aim of this study is to compare the results obtained by a lubrication one-dimensional model, numerical volume of fluid-large eddy simulation (VOF-LES) modeling and an experimental approach. The investigation emphasizes the effect of the controlling wiping parameters, i.e., the pressure gradient and shear stress distributions induced by the jet, on the shape of the liquid film. Those profiles obtained experimentally and numerically for a jet impinging on a dry fixed surface are compared. The effect of the substrate motion and the presence of the dragged liquid film on these actuators are analyzed through numerical simulations. Good agreement is found between the film thickness profile in the wiping zone obtained from the VOF-LES simulations and with the analytical model, provided that a good model for the wiping actuators is used. The effect of the gas-jet nozzle to substrate standoff distance on the final coating thickness is analyzed; the experimental and predicted values are compared for a wide set of conditions. Finally, the occurrence of the splashing phenomenon, which is characterized by the ejection of droplets from the runback film flow at jet impingement, thus limiting the wiping process, is investigated through experiments and numerical simulations.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, Charles D.

1981-01-01

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, Charles D. [Livermore, CA

1980-02-26

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member.

Cause and Effect of Feedback: Multiphase Gas in Cluster Cores Heated by AGN Jets

NASA Astrophysics Data System (ADS)

Gaspari, M.; Ruszkowski, M.; Sharma, P.

2012-02-01

Multiwavelength data indicate that the X-ray-emitting plasma in the cores of galaxy clusters is not cooling catastrophically. To a large extent, cooling is offset by heating due to active galactic nuclei (AGNs) via jets. The cool-core clusters, with cooler/denser plasmas, show multiphase gas and signs of some cooling in their cores. These observations suggest that the cool core is locally thermally unstable while maintaining global thermal equilibrium. Using high-resolution, three-dimensional simulations we study the formation of multiphase gas in cluster cores heated by collimated bipolar AGN jets. Our key conclusion is that spatially extended multiphase filaments form only when the instantaneous ratio of the thermal instability and free-fall timescales (t TI/t ff) falls below a critical threshold of ≈10. When this happens, dense cold gas decouples from the hot intracluster medium (ICM) phase and generates inhomogeneous and spatially extended Hα filaments. These cold gas clumps and filaments "rain" down onto the central regions of the core, forming a cold rotating torus and in part feeding the supermassive black hole. Consequently, the self-regulated feedback enhances AGN heating and the core returns to a higher entropy level with t TI/t ff > 10. Eventually, the core reaches quasi-stable global thermal equilibrium, and cold filaments condense out of the hot ICM whenever t TI/t ff <~ 10. This occurs despite the fact that the energy from AGN jets is supplied to the core in a highly anisotropic fashion. The effective spatial redistribution of heat is enabled in part by the turbulent motions in the wake of freely falling cold filaments. Increased AGN activity can locally reverse the cold gas flow, launching cold filamentary gas away from the cluster center. Our criterion for the condensation of spatially extended cold gas is in agreement with observations and previous idealized simulations.

A CFD study of gas-solid jet in a CFB riser flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Tingwen; Guenther, Chris

2012-03-01

Three-dimensional high-resolution numerical simulations of a gas–solid jet in a high-density riser flow were conducted. The impact of gas–solid injection on the riser flow hydrodynamics was investigated with respect to voidage, tracer mass fractions, and solids velocity distribution. The behaviors of a gas–solid jet in the riser crossflow were studied through the unsteady numerical simulations. Substantial separation of the jetting gas and solids in the riser crossflow was observed. Mixing of the injected gas and solids with the riser flow was investigated and backmixing of gas and solids was evaluated. In the current numerical study, both the overall hydrodynamics ofmore » riser flow and the characteristics of gas–solid jet were reasonably predicted compared with the experimental measurements made at NETL.« less

Atmospheric-pressure plasma jets: Effect of gas flow, active species, and snake-like bullet propagation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, S.; Wang, Z.; Huang, Q.

2013-02-15

Cold atmospheric-pressure plasma jets have recently attracted enormous interest owing to numerous applications in plasma biology, health care, medicine, and nanotechnology. A dedicated study of the interaction between the upstream and downstream plasma plumes revealed that the active species (electrons, ions, excited OH, metastable Ar, and nitrogen-related species) generated by the upstream plasma plume enhance the propagation of the downstream plasma plume. At gas flows exceeding 2 l/min, the downstream plasma plume is longer than the upstream plasma plume. Detailed plasma diagnostics and discharge species analysis suggest that this effect is due to the electrons and ions that are generatedmore » by the upstream plasma and flow into the downstream plume. This in turn leads to the relatively higher electron density in the downstream plasma. Moreover, high-speed photography reveals a highly unusual behavior of the plasma bullets, which propagate in snake-like motions, very differently from the previous reports. This behavior is related to the hydrodynamic instability of the gas flow, which results in non-uniform distributions of long-lifetime active species in the discharge tube and of surface charges on the inner surface of the tube.« less

Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

NASA Astrophysics Data System (ADS)

Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

2015-09-01

Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

Cold gas and the disruptive effect of a young radio jet

NASA Astrophysics Data System (ADS)

Morganti, R.; Oosterloo, T.; Maccagni, F. M.; Geréb, K.; Oonk, J. B. R.; Tadhunter, C. N.

2016-02-01

Newly born and young radio sources are in a delicate phase of their life. Their jets are fighting their way through the surrounding gaseous medium, strongly experiencing this interaction while, at the same time, impacting and affecting the interstellar medium (ISM). Quantifying this interplay has far reaching implications: the rate of occurrence and the magnitude of the interaction between radio jets and ISM can have consequences for the evolution of the host galaxy. Despite the hostile conditions, cold gas - neutral atomic hydrogen and molecular - has been often found in these objects and can be also associated to fast outflows. Here we present the results from two studies of H I and molecular gas illustrating what can be learned from these phases of the gas. We first describe a statistical study of the occurrence and kinematics of H I observed in absorption with the Westerbork Synthesis Radio telescope. This allows a comparison between the properties of the gas in extended and in compact/young radio sources. The study shows that the young radio sources not only have an higher detection rate of H I, but also systematically broader and more asymmetric H I profiles, most of them blueshifted. This supports the idea that we are looking at young radio jets making their way through the surrounding ISM, which also appears to be, on average, richer in gas than in evolved radio sources. Signatures of the impact of the jet are seen in the kinematics of the gas, but the resulting outflows may be characteristic of only the initial phase of the radio source evolution. However, even among the young sources, we identify a population that remains undetected in H I even after stacking their profiles. Orientation effects can only partly explain the result. These objects either are genuinely gas-poor or have different conditions of the medium, e.g. higher spin temperature. The upcoming blind H I surveys which are about to start with large-field-of-view radio facilities (i.e. Apertif

LPWA using supersonic gas jet with tailored density profile

NASA Astrophysics Data System (ADS)

Kononenko, O.; Bohlen, S.; Dale, J.; D'Arcy, R.; Dinter, M.; Erbe, J. H.; Indorf, G.; di Lucchio, L.; Goldberg, L.; Gruse, J. N.; Karstensen, S.; Libov, V.; Ludwig, K.; Martinez de La Ossa, A.; Marutzky, F.; Niroula, A.; Osterhoff, J.; Quast, M.; Schaper, L.; Schwinkendorf, J.-P.; Streeter, M.; Tauscher, G.; Weichert, S.; Palmer, C.; Horbatiuk, Taras

2016-10-01

Laser driven plasma wakefield accelerators have been explored as a potential compact, reproducible source of relativistic electron bunches, utilising an electric field of many GV/m. Control over injection of electrons into the wakefield is of crucial importance in producing stable, mono-energetic electron bunches. Density tailoring of the target, to control the acceleration process, can also be used to improve the quality of the bunch. By using gas jets to provide tailored targets it is possible to provide good access for plasma diagnostics while also producing sharp density gradients for density down-ramp injection. OpenFOAM hydrodynamic simulations were used to investigate the possibility of producing tailored density targets in a supersonic gas jet. Particle-in-cell simulations of the resulting density profiles modelled the effect of the tailored density on the properties of the accelerated electron bunch. Here, we present the simulation results together with preliminary experimental measurements of electron and x-ray properties from LPWA experiments using gas jet targets and a 25 TW, 25 fs Ti:Sa laser system at DESY.

Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

NASA Astrophysics Data System (ADS)

Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

2017-05-01

The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

Cryogenic target formation using cold gas jets

DOEpatents

Hendricks, C.D.

1980-02-26

A method and apparatus using cold gas jets for producing a substantially uniform layer of cryogenic materials on the inner surface of hollow spherical members having one or more layers, such as inertially imploded targets are disclosed. By vaporizing and quickly refreezing cryogenic materials contained within a hollow spherical member, a uniform layer of the materials is formed on an inner surface of the spherical member. Basically the method involves directing cold gas jets onto a spherical member having one or more layers or shells and containing the cryogenic material, such as a deuterium-tritium (DT) mixture, to freeze the contained material, momentarily heating the spherical member so as to vaporize the contained material, and quickly refreezing the thus vaporized material forming a uniform layer of cryogenic material on an inner surface of the spherical member. 4 figs.

Reconfinement and loss of stability in jets from active galactic nuclei

NASA Astrophysics Data System (ADS)

Gourgouliatos, Konstantinos N.; Komissarov, Serguei S.

2018-02-01

Jets powered by active galactic nuclei appear impressively stable compared with their terrestrial and laboratory counterparts—they can be traced from their origin to distances exceeding their injection radius by up to a billion times1,2. However, some less energetic jets get disrupted and lose their coherence on the scale of their host galaxy1,3. Quite remarkably, on the same scale, these jets are expected to become confined by the thermal pressure of the intra-galactic gas2. Motivated by these observations, we have started a systematic study of active galactic nuclei jets undergoing reconfinement via computer simulations. Here, we show that in the case of unmagnetized relativistic jets, the reconfinement is accompanied by the development of an instability and transition to a turbulent state. During their initial growth, the perturbations have a highly organized streamwise-oriented structure, indicating that it is not the Kelvin-Helmholtz instability, the instability which has been the main focus of the jet stability studies so far4,5. Instead, it is closely related to the centrifugal instability6. This instability is likely to be behind the division of active galactic nuclei jets into two morphological types in the Fanaroff-Riley classification7.

High-Resolution Simulations of Gas-Solids Jet Penetration Into a High Density Riser Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Tingwen

2011-05-01

High-resolution simulations of a gas-solids jet in a 0.3 m diameter and 15.9 m tall circulating fluidized bed (CFB) riser were conducted with the open source software-MFIX. In the numerical simulations, both gas and solids injected through a 1.6 cm diameter radial-directed tube 4.3 m above the bottom distributor were tracked as tracers, which enable the analysis of the characteristics of a two-phase jet. Two jetting gas velocities of 16.6 and 37.2 m/s were studied with the other operating conditions fixed. Reasonable flow hydrodynamics with respect to overall pressure drop, voidage, and solids velocity distributions were predicted. Due to themore » different dynamic responses of gas and particles to the crossflow, a significant separation of gas and solids within the jet region was predicted for both cases. In addition, the jet characteristics based on tracer concentration and tracer mass fraction profiles at different downstream levels are discussed. Overall, the numerical predictions compare favorably to the experimental measurements made at NETL.« less

Transitional Gas Jet Diffusion Flames in Microgravity

NASA Technical Reports Server (NTRS)

Agrawal, Ajay K.; Alammar, Khalid; Gollahalli, S. R.; Griffin, DeVon (Technical Monitor)

2000-01-01

Drop tower experiments were performed to identify buoyancy effects in transitional hydrogen gas jet diffusion flames. Quantitative rainbow schlieren deflectometry was utilized to optically visualize the flame and to measure oxygen concentration in the laminar portion of the flame. Test conditions consisted of atmospheric pressure flames burning in quiescent air. Fuel from a 0.3mm inside diameter tube injector was issued at jet exit Reynolds numbers (Re) of 1300 to 1700. Helium mole percentage in the fuel was varied from 0 to 40%. Significant effects of buoyancy were observed in near field of the flame even-though the fuel jets were momentum-dominated. Results show an increase of breakpoint length in microgravity. Data suggest that transitional flames in earth-gravity at Re<1300 might become laminar in microgravity.

Buoyancy Effects on Flow Structure and Instability of Low-Density Gas Jets

NASA Technical Reports Server (NTRS)

Pasumarthi, Kasyap Sriramachandra

2004-01-01

A low-density gas jet injected into a high-density ambient gas is known to exhibit self-excited global oscillations accompanied by large vortical structures interacting with the flow field. The primary objective of the proposed research is to study buoyancy effects on the origin and nature of the flow instability and structure in the near-field of low-density gas jets. Quantitative rainbow schlieren deflectometry, Computational fluid dynamics (CFD) and Linear stability analysis were the techniques employed to scale the buoyancy effects. The formation and evolution of vortices and scalar structure of the flow field are investigated in buoyant helium jets discharged from a vertical tube into quiescent air. Oscillations at identical frequency were observed throughout the flow field. The evolving flow structure is described by helium mole percentage contours during an oscillation cycle. Instantaneous, mean, and RMS concentration profiles are presented to describe interactions of the vortex with the jet flow. Oscillations in a narrow wake region near the jet exit are shown to spread through the jet core near the downstream location of the vortex formation. The effects of jet Richardson number on characteristics of vortex and flow field are investigated and discussed. The laminar, axisymmetric, unsteady jet flow of helium injected into air was simulated using CFD. Global oscillations were observed in the flow field. The computed oscillation frequency agreed qualitatively with the experimentally measured frequency. Contours of helium concentration, vorticity and velocity provided information about the evolution and propagation of vortices in the oscillating flow field. Buoyancy effects on the instability mode were evaluated by rainbow schlieren flow visualization and concentration measurements in the near-field of self-excited helium jets undergoing gravitational change in the microgravity environment of 2.2s drop tower at NASA John H. Glenn Research Center. The jet

Liquid jet pumped by rising gas bubbles

NASA Technical Reports Server (NTRS)

Hussain, N. A.; Siegel, R.

1975-01-01

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

[Microbial Processes and Genesis of Methane Gas Jets in the Coastal Areas of the Crimea Peninsula].

PubMed

Malakhova, T V; Kanapatskii, T A; Egorov, V N; Malakhova, L V; Artemov, Yu G; Evtushenko, D B; Gulin, S B; Pimenov, N V

2015-01-01

Hydroasoustic techniques were used for detection and mapping of gas jet areas in the coastal regions of the Crimean peninsula. Gas seep areas in the bays Laspi, Khersones, and Kazach'ya were chosen for detailed microbiological investigation. The first type of gas jets, observed in the Laspi Bay, was probably associated with discarge of deep thermogenic methane along the faults. Methane isotopic composition was char- acterized by Δ13C of -35.3 degrees. While elevated rates of aerobic methane oxidation were revealed in the sandy sediments adjacent to the methane release site, no evidence of bacterial mats was found. The second type of gas emission, observed in the Khersones Bay, was accompanied by formation of bacterial biofilms of the "Thiodendron" microbial community type, predominated by filamentous, spirochete-like organisms, in the areas of gas seepage. The isotopic composition of methane was there considerably lower (-60.4 degrees), indicating a considerable contribution of modern microbial methane to the gas bubbles discharged in this bay. Activity of the third type of gas emission, the seeps of the Kazach'ya Bay, probably depended directly on modern microbial processes of organic matter degradation in the upper sediment layers. The rates of sulfate reduction and methanogenesis were 260 and 34 μmol dm(-3) day(-1), respectively. Our results indicate different mechanisms responsible for formation of methane jets in the Laspi Bay and in the coastal areas of the Heracles Peninsula, where the bays Kazach'ya and Khersones are located.

Active Region Jets II: Triggering and Evolution of Violent Jets

NASA Astrophysics Data System (ADS)

Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David; Panesar, Navdeep K.; Martinez, Francisco

2017-08-01

We study a series of X-ray-bright, rapidly evolving active-region coronal jets outside the leading sunspot of AR 12259, using Hinode/XRT, SDO/AIA and HMI, and IRIS/SJ data. The detailed evolution of such rapidly evolving “violent” jets remained a mystery after our previous investigation of active region jets (Sterling et al. 2016, ApJ, 821, 100). The jets we investigate here erupt from three localized subregions, each containing a rapidly evolving (positive) minority-polarity magnetic-flux patch bathed in a (majority) negative-polarity magnetic-flux background. At least several of the jets begin with eruptions of what appear to be thin (thickness ˜<2‧‧) miniature-filament (minifilament) “strands” from a magnetic neutral line where magnetic flux cancelation is ongoing, consistent with the magnetic configuration presented for coronal-hole jets in Sterling et al. (2015, Nature, 523, 437). For some jets strands are difficult/ impossible to detect, perhaps due to their thinness, obscuration by surrounding bright or dark features, or the absence of erupting cool-material minifilaments in those jets. Tracing in detail the flux evolution in one of the subregions, we find bursts of strong jetting occurring only during times of strong flux cancelation. Averaged over seven jetting episodes, the cancelation rate was ~1.5×10^19 Mx/hr. An average flux of ~5×10^18 Mx canceled prior to each episode, arguably building up ~10^28—10^29 ergs of free magnetic energy per jet. From these and previous observations, we infer that flux cancelation is the fundamental process responsible for the pre-eruption buildup and triggering of at least many jets in active regions, quiet regions, and coronal holes.

Reprint of: Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

NASA Astrophysics Data System (ADS)

Chipps, K. A.

2018-01-01

Explosive stellar environments are sometimes driven by nuclear reactions on short-lived, radioactive nuclei. These reactions often drive the stellar explosion, alter the observable light curves produced, and dictate the final abundances of the isotopes created. Unfortunately, many reaction rates at stellar temperatures cannot be directly measured in the laboratory, due to the physical limitations of ultra-low cross sections and high background rates. An additional complication arises because many of the important reactions involve radioactive nuclei which have lifetimes too short to be made into a target. As such, direct reactions require very intense and pure beams of exotic nuclei. Indirect approaches with both stable and radioactive beams can, however, provide crucial information on the nuclei involved in these astrophysical reactions. A major development toward both direct and indirect studies of nuclear reactions rates is the commissioning of the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) supersonic gas jet target. The JENSA system provides a pure, homogeneous, highly localized, dense, and robust gaseous target for radioactive ion beam studies. Charged-particle reactions measurements made with gas jet targets can be cleaner and display better resolution than with traditional targets. With the availability of pure and localized gas jet targets in combination with developments in exotic radioactive ion beams and next-generation detector systems, the range of reaction studies that are experimentally possible is vastly expanded. Various representative cases will be discussed.

Effect of gas mass flux on cryogenic liquid jet breakup

NASA Technical Reports Server (NTRS)

Ingebo, R. D.

1992-01-01

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

Real-time sensing and gas jet mitigation of VDEs on Alcator C-Mod

NASA Astrophysics Data System (ADS)

Granetz, R. S.; Wolfe, S. M.; Izzo, V. A.; Reinke, M. L.; Terry, J. L.; Hughes, J. W.; Zhurovich, K.; Whyte, D. G.; Bakhtiari, M.; Wurden, G.

2006-10-01

Experiments have been carried out in Alcator C-Mod to test the effectiveness of gas jet disruption mitigation of VDEs with real-time detection and triggering by the C-Mod digital plasma control system (DPCS). The DPCS continuously computes the error in the plasma vertical position from the magnetics diagnostics. When this error exceeds an adjustable preset value, the DPCS triggers the gas jet valve (with a negligible latency time). The high-pressure gas (argon) only takes a few milliseconds to enter the vacuum chamber and begin affecting the plasma, but this is comparable to the VDE timescale on C-Mod. Nevertheless, gas jet injection reduced the halo current, increased the radiated power fraction, and reduced the heating of the divertor compared to unmitigated disruptions, but not quite as well as in earlier mitigation experiments with vertically stable plasmas. Presumably a faster overall response time would be beneficial, and several ways to achieve this will also be discussed.

Spray Characterization of Gas-to-Liquid Synthetic Jet Fuels

NASA Astrophysics Data System (ADS)

Kannaiyan, Kumaran; Sadr, Reza; GTL jet fuel Consortium Team

2012-11-01

Gas-to-Liquid (GTL) Synthetic Paraffinic Kerosene (SPK) fuel obtained from Fischer-Tropsch synthesis has grabbed the global attention due to its cleaner combustion characteristics. GTL fuels are expected to meet the vital qualities such as atomization, combustion and emission characteristics of conventional jet fuels. It is imperative to understand fuel atomization in order to gain insights on the combustion and emission aspects of an alternative fuel. In this work spray characteristics of GTL-SPK, which could be used as a drop-in fuel in aircraft gas turbine engines, is studied. This work outlines the spray experimental facility, the methodology used and the results obtained using two SPK's with different chemical compositions. The spray characteristics, such as droplet size and distribution, are presented at three differential pressures across a simplex nozzle and compared with that of the conventional Jet A-1 fuel. Experimental results clearly show that although the chemical composition is significantly different between SPK's, the spray characteristics are not very different. This could be attributed to the minimal difference in fluid properties between the SPK's. Also, the spray characteristics of SPK's show close resemblance to the spray characteristics of Jet A-1 fuel.

Note: Design and investigation of a multichannel plasma-jet triggered gas switch.

PubMed

Tie, Weihao; Liu, Xuandong; Zhang, Qiaogen; Liu, Shanhong

2014-07-01

We described the fabrication and testing of a multichannel plasma-jet triggered gas switch (MPJTGS). A novel six-channel annular micro-plasma-gun was embedded in the trigger electrode to generate multichannel plasma jets as a nanosecond trigger pulse arrived. The gas breakdown in multiple sites of the spark gap was induced and fixed around jet orifices by the plasma jets. We tested the multichannel discharge characteristics of the MPJTGS in two working modes with charge voltage of 50 kV, trigger voltage of +40 kV (25 ns rise time), and trigger energy of 240 J, 32 J, and 2 J, respectively, at different working coefficients. Results show that the average number of discharge channels increased as the trigger energy increased, and decreased as the working coefficient decreased. At a working coefficient of 87.1% and trigger energy of 240 J, the average number of discharge channels in Mode II could reach 4.1.

Numerical simulation of interaction between chemically active exhaust and a jet blast deflector

NASA Astrophysics Data System (ADS)

Korotaeva, T. A.; Turchinovich, A. O.

2017-10-01

The interaction of chemically active exhausts of aircraft engines with jet blast deflector (JBD) of various configurations has been considered at the stage of ground run procedure. The problem is modeled in the 3-D approximation in the framework of the numerical solution of the Navier-Stokes equations taking into account the kinetic model of the interaction of between the components of engine exhaust and air. A complex field of gasdynamic flow that is realized when jets emerge from nozzles and interact with each other, with air, with a gas deflector has been studied. The main purpose of the study is to prove the concept that it is possible to generate a vortex flow that can not only change the direction of the jets, but also contribute to the lifting of the mass of pollutants and their dispersion in the atmosphere using a gas deflector shape.

An experimental investigation of gas jets in confined swirling air flow

NASA Technical Reports Server (NTRS)

Mongia, H.; Ahmed, S. A.; Mongia, H. C.

1984-01-01

The fluid dynamics of jets in confined swirling flows which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling flows were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined flow with large area ratio are highly dissipative which results in both air and helium/air jet centerline velocity decays. For air jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling flow. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/air jets. The subsequent flow and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.

Investigation of the on-axis atom number density in the supersonic gas jet under high gas backing pressure by simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Guanglong; Xu, Yi; Cao, Yunjiu

The supersonic gas jets from conical nozzles are simulated using 2D model. The on-axis atom number density in gas jet is investigated in detail by comparing the simulated densities with the idealized densities of straight streamline model in scaling laws. It is found that the density is generally lower than the idealized one and the deviation between them is mainly dependent on the opening angle of conical nozzle, the nozzle length and the gas backing pressure. The density deviation is then used to discuss the deviation of the equivalent diameter of a conical nozzle from the idealized d{sub eq} inmore » scaling laws. The investigation on the lateral expansion of gas jet indicates the lateral expansion could be responsible for the behavior of the density deviation. These results could be useful for the estimation of cluster size and the understanding of experimental results in laser-cluster interaction experiments.« less

Investigation of acoustic and gas dynamic characteristics of strongly swirled turbulent jets

NASA Astrophysics Data System (ADS)

Krasheninnikov, S. Yu; Maslov, VP; Mironov, AK; Toktaliev, PD

2018-03-01

Generalization of the series of experimental and numerical results for properties and characteristics of swirling jets with high swirling intensity W0>1 is considered. These jets are typically used in gas turbine aviation engines for intensification of mixing process and combustion process stabilization. Flow structures in swirling jets and in the near-field are analyzed. It is shown, that, in the main, the flow structure behind the swirling device can be determined by swirling intensity W 0 and acoustic fluctuations field formed far from the jet boundaries. Experimental measurements and numerical simulation of the noise levels of the highly swirling jet are performed using Ffowcs-Williams-Hawkins analogy. Maximum levels of noise axis are observed at angles of 50°-70° from the jet.

Coupling modes between liquid/gas coaxial jets and transverse acoustic waves

NASA Astrophysics Data System (ADS)

Helland, Chad; Hilliker, Cullen; Forliti, David; University of St. Thomas Team

2017-11-01

The interactions between shear flows and acoustic disturbances plays a very important role in many propulsion and energy applications. Liquid jets, either independent or air assisted, respond to acoustic disturbances in a manner that alters the primary and secondary atomization processes. The current study focused on the response of an air-assisted liquid jet to disturbances associated with a transverse acoustic wave. The jet is placed in the pressure node (velocity antinode) region of the resonant mode shape. It has been shown in previous studies, under certain conditions, that the acoustic forces can cause the jet flow to distort and atomize. Both liquid and coaxial gas/ liquid jet flows have been shown to distort via acoustic forces. The purpose of the current study is to understand the predictive characteristics that cause the distortion behaviors of a liquid and coaxial jet flow, and how a how a coaxial flow affects the behavior.

AGN jet feedback on a moving mesh: cocoon inflation, gas flows and turbulence

NASA Astrophysics Data System (ADS)

Bourne, Martin A.; Sijacki, Debora

2017-12-01

In many observed galaxy clusters, jets launched by the accretion process on to supermassive black holes, inflate large-scale cavities filled with energetic, relativistic plasma. This process is thought to be responsible for regulating cooling losses, thus moderating the inflow of gas on to the central galaxy, quenching further star formation and maintaining the galaxy in a red and dead state. In this paper, we implement a new jet feedback scheme into the moving mesh-code AREPO, contrast different jet injection techniques and demonstrate the validity of our implementation by comparing against simple analytical models. We find that jets can significantly affect the intracluster medium (ICM), offset the overcooling through a number of heating mechanisms, as well as drive turbulence, albeit within the jet lobes only. Jet-driven turbulence is, however, a largely ineffective heating source and is unlikely to dominate the ICM heating budget even if the jet lobes efficiently fill the cooling region, as it contains at most only a few per cent of the total injected energy. We instead show that the ICM gas motions, generated by orbiting substructures, while inefficient at heating the ICM, drive large-scale turbulence and when combined with jet feedback, result in line-of-sight velocities and velocity dispersions consistent with the Hitomi observations of the Perseus cluster.

Numerical Simulation and Industrial Experimental Research on the Coherent Jet with "CH4 + N2" Mixed Fuel Gas

NASA Astrophysics Data System (ADS)

Hu, Shaoyan; Zhu, Rong; Dong, Kai; Liu, Runzao

2018-06-01

Coherent jet technology is widely used in the electric arc furnace (EAF) steelmaking process to deliver more energy and momentum into the molten steel bath. Meanwhile, the characteristics of a coherent jet using pure CH4 as the fuel gas have been well investigated in previous studies. To reduce the consumption of CH4, coherent jet technology using "CH4 + N2" mixed fuel gas instead of pure CH4 was proposed and studied in detail by numerical simulation in the present work. The Eddy Dissipation Concept model, which has detailed chemical kinetic mechanisms, was adopted to model the fuel gas combustion reactions. Experimental measurements were carried out to validate the accuracy of the computational model. The present study shows that the jet characteristics of the main oxygen improve along with the increase of the CH4 ratio in fuel gas and with the increase of the flow rate of fuel gas. When the CH4 ratio in the fuel gas is 25 pct, the fuel gas flow rate only has a limited influence on the jet characteristics, unlike the rest of the fuel gas compositions, because a high N2 proportion deteriorates the combustion performance and leads to severe incomplete combustion. Moreover, a false potential core phenomenon was observed and explained in the present study. Based on the average values, the jet length of a coherent jet with 75 pct CH4 can achieve 89.8 pct of that with 100 pct CH4. Finally, an industrial experiment was carried out on a commercial 100t EAF using coherent jet with 75 pct CH4, showing that the average CH4 consumption was reduced from 3.84 to 3.05 Nm3 t-1 under the premise of no obvious changes in the other production indexes.

Combustion Gas Properties I-ASTM Jet a Fuel and Dry Air

NASA Technical Reports Server (NTRS)

Jones, R. E.; Trout, A. M.; Wear, J. D.; Mcbride, B. J.

1984-01-01

A series of computations was made to produce the equilibrium temperature and gas composition for ASTM jet A fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0.

Effects of buoyancy on gas jet diffusion flames

NASA Technical Reports Server (NTRS)

Bahadori, M. Yousef; Edelman, Raymond B.

1993-01-01

The objective of this effort was to gain a better understanding of the fundamental phenomena involved in laminar gas jet diffusion flames in the absence of buoyancy by studying the transient phenomena of ignition and flame development, (quasi-) steady-state flame characteristics, soot effects, radiation, and, if any, extinction phenomena. This involved measurements of flame size and development, as well as temperature and radiation. Additionally, flame behavior, color, and luminosity were observed and recorded. The tests quantified the effects of Reynolds number, nozzle size, fuel reactivity and type, oxygen concentration, and pressure on flame characteristics. Analytical and numerical modeling efforts were also performed. Methane and propane flames were studied in the 2.2 Second Drop Tower and the 5.18-Second Zero-Gravity Facility of NASA LeRC. In addition, a preliminary series of tests were conducted in the KC-135 research aircraft. Both micro-gravity and normal-gravity flames were studied in this program. The results have provided unique and new information on the behavior and characteristics of gas jet diffusion flames in micro-gravity environments.

Effects of Jet Swirl on Mixing of a Light Gas Jet in a Supersonic Airstream

NASA Technical Reports Server (NTRS)

Doerner, Steven E.; Cutler, Andrew D.

1999-01-01

A non reacting experiment was performed to investigate the effects of jet swirl on mixing of a light gas jet in a supersonic airstream. The experiment consisted of two parts. The first part was an investigation of the effects of jet swirl and skew on the mixing and penetration of a 25 deg. supersonic jet injected from a flat surface (flush wall injection) into a supersonic ducted airflow. Specifically, the objective was to determine whether the jet would mix more rapidly if the jet were swirling, and whether swirl, with and without skew, causes the injectant-air plume to have a net circulation (i.e., a single or dominant vortex). The second part was a preliminary study of the mixing of swirling jets injected from the base of a skewed ramp. The hypothesis was that favorable interactions between vorticity generated by the swirling jet and vortices generated by the ramp could produce mixing enhancements. Both parts of the experiment were conducted at equal injectant mass flow rate and total pressure. The results for the flush wall injection cases indicate that, except relatively close to the injection point, swirl, with or without skew, does not enhance the mixing of the jet, and can in fact reduce penetration. In addition, a plume with significant net circulation is not generated, as had previously been believed. The results for the ramp cases indicated no improvements in mixing in comparison with the baseline (swept ramp injector) case. However, it was not possible to determine the vorticity mechanisms underlying the poor performance, since no measurements of vorticity were made. Thus, since many geometric parameters were chosen arbitrarily, the results are inconclusive for this class of injector.

Radio jets clearing the way through galaxies: the view from Hi and molecular gas

NASA Astrophysics Data System (ADS)

Morganti, Raffaella

2015-03-01

Massive gas outflows are considered a key component in the process of galaxy formation and evolution. Because of this, they are the topic of many studies aimed at learning more about their occurrence, location and physical conditions as well as the mechanism(s) at their origin. This contribution presents recent results on two of the best examples of jet-driven outflows traced by cold and molecular gas. Thanks to high-spatial resolution observations, we have been able to locate the region where the outflow occurs. This appears to be coincident with bright radio features and regions where the interaction between radio plasma jet and ISM is known to occur, thus strongly supporting the idea of jet-driven outflows. We have also imaged the distribution of the outflowing gas. The results clearly show the effect that expanding radio jets and lobes have on the ISM. This appears to be in good agreement with what predicted from numerical simulations. Furthermore, the results show that cold gas is associated with these powerful phenomena and can be formed - likely via efficient cooling - even after a strong interaction and fast shocks. The discovery of similar fast outflows of cold gas in weak radio sources is further increasing the relevance that the effect of the radio plasma can have on the surrounding medium and on the host galaxy.

Toward the Active Control of Heat Transfer in the Hot Gas Path of Gas Turbines

NASA Technical Reports Server (NTRS)

Oertling, Jeremiah E.

2003-01-01

The work at NASA this summer has focused on assisting the Professor's project, namely "Toward the Active Control of Heat Transfer in the Hot Gas Path of Gas Turbines." The mode of controlling the Heat Transfer that the project focuses on is film cooling. Film cooling is used in high temperature regions of a gas turbine and extends the life of the components exposed to these extreme temperatures. A "cool" jet of air is injected along the surface of the blade and this layer of cool air shields the blade from the high temperatures. Cool is a relative term. The hot gas path temperatures reach on the order of 1500 to 2000 K. The "coo" air is on the order of 700 to 1000 K. This cooler air is bled off of an appropriate compressor stage. The next parameter of interest is the jet s position and orientation in the flow-field.

Solar Active Region Coronal Jets. II. Triggering and Evolution of Violent Jets

NASA Astrophysics Data System (ADS)

Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Martinez, Francisco

2017-07-01

We study a series of X-ray-bright, rapidly evolving active region coronal jets outside the leading sunspot of AR 12259, using Hinode/X-ray telescope, Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI), and Interface Region Imaging Spectrograph (IRIS) data. The detailed evolution of such rapidly evolving “violent” jets remained a mystery after our previous investigation of active region jets. The jets we investigate here erupt from three localized subregions, each containing a rapidly evolving (positive) minority-polarity magnetic-flux patch bathed in a (majority) negative-polarity magnetic-flux background. At least several of the jets begin with eruptions of what appear to be thin (thickness ≲ 2\\prime\\prime ) miniature-filament (minifilament) “strands” from a magnetic neutral line where magnetic flux cancelation is ongoing, consistent with the magnetic configuration presented for coronal-hole jets in Sterling et al. (2016). Some jets strands are difficult/impossible to detect, perhaps due to, e.g., their thinness, obscuration by surrounding bright or dark features, or the absence of erupting cool-material minifilaments in those jets. Tracing in detail the flux evolution in one of the subregions, we find bursts of strong jetting occurring only during times of strong flux cancelation. Averaged over seven jetting episodes, the cancelation rate was ˜ 1.5× {10}19 Mx hr-1. An average flux of ˜ 5× {10}18 Mx canceled prior to each episode, arguably building up ˜1028-1029 erg of free magnetic energy per jet. From these and previous observations, we infer that flux cancelation is the fundamental process responsible for the pre-eruption build up and triggering of at least many jets in active regions, quiet regions, and coronal holes.

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.

Buoyancy Effects on Flow Transition in Hydrogen Gas Jet Diffusion Flames

NASA Technical Reports Server (NTRS)

Albers, Burt W.; Agrawal, Ajay K.; Griffin, DeVon (Technical Monitor)

2000-01-01

Experiments were performed in earth-gravity to determine how buoyancy affected transition from laminar to turbulent flow in hydrogen gas jet diffusion flames. The jet exit Froude number characterizing buoyancy in the flame was varied from 1.65 x 10(exp 5) to 1.14 x 10(exp 8) by varying the operating pressure and/or burner inside diameter. Laminar fuel jet was discharged vertically into ambient air flowing through a combustion chamber. Flame characteristics were observed using rainbow schlieren deflectometry, a line-of-site optical diagnostic technique. Results show that the breakpoint length for a given jet exit Reynolds number increased with increasing Froude number. Data suggest that buoyant transitional flames might become laminar in the absence of gravity. The schlieren technique was shown as effective in quantifying the flame characteristics.

AGN feedback compared: jets versus radiation

NASA Astrophysics Data System (ADS)

Cielo, Salvatore; Bieri, Rebekka; Volonteri, Marta; Wagner, Alexander Y.; Dubois, Yohan

2018-06-01

Feedback by active galactic nuclei (AGNs) is often divided into quasar and radio mode, powered by radiation or radio jets, respectively. Both are fundamental in galaxy evolution, especially in late-type galaxies, as shown by cosmological simulations and observations of jet-ISM (interstellar medium) interactions in these systems. We compare AGN feedback by radiation and by collimated jets through a suite of simulations, in which a central AGN interacts with a clumpy, fractal galactic disc. We test AGNs of 1043 and 1046 erg s-1, considering jets perpendicular or parallel to the disc. Mechanical jets drive the more powerful outflows, exhibiting stronger mass and momentum coupling with the dense gas, while radiation heats and rarefies the gas more. Radiation and perpendicular jets evolve to be quite similar in outflow properties and effect on the cold ISM, while inclined jets interact more efficiently with all the disc gas, removing the densest 20 {per cent} in 20 Myr, and thereby reducing the amount of cold gas available for star formation. All simulations show small-scale inflows of 0.01-0.1 M⊙ yr-1, which can easily reach down to the Bondi radius of the central supermassive black hole (especially for radiation and perpendicular jets), implying that AGNs modulate their own duty cycle in a feedback/feeding cycle.

3D printing of gas jet nozzles for laser-plasma accelerators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Döpp, A.; Guillaume, E.; Thaury, C.

2016-07-15

Recent results on laser wakefield acceleration in tailored plasma channels have underlined the importance of controlling the density profile of the gas target. In particular, it was reported that the appropriate density tailoring can result in improved injection, acceleration, and collimation of laser-accelerated electron beams. To achieve such profiles, innovative target designs are required. For this purpose, we have reviewed the usage of additive layer manufacturing, commonly known as 3D printing, in order to produce gas jet nozzles. Notably we have compared the performance of two industry standard techniques, namely, selective laser sintering (SLS) and stereolithography (SLA). Furthermore we havemore » used the common fused deposition modeling to reproduce basic gas jet designs and used SLA and SLS for more sophisticated nozzle designs. The nozzles are characterized interferometrically and used for electron acceleration experiments with the SALLE JAUNE terawatt laser at Laboratoire d’Optique Appliquée.« less

Machines employing a hot gas jet to cut metals and nonmetallic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polyaev, V.M.; Aleksandrenkov, V.P.

1995-07-01

The flame-cutting of metals is a basic materials-processing operation performed in the course of machine-building and, in some sectors (shipbuilding, aircraft construction, petrochemicals) it is the most important operation. In addition, this method of cutting remains the main operation performed in the processing of scrap metal. The importance of it has occasioned the development of a wide range of cutting tools within just the last decade. Not surprisingly, VNIIavtogen-mash (the All-Union Scientific Research Institute of Machinery for the Gas Welding and Cutting of Metals) is the leading designer of metal-cutting tools in this country. The problem of efficiently cutting metalsmore » is gaining in importance and will continue to do so in coming years in connection with the conversion of military hardware to other uses, the decommissioning of old and obsolete equipment, and utilization of the enormous reserves of scrap in this country. There will thus be a significant increase in the amounts of existing high-alloy steels, nonferrous metals and their alloys, and composites that require cutting. A wide range of cutters is available for the gas-flame cutting of metals, Liquid fuels based on petroleum products are promising from the viewpoint of energy efficiency and performance. The operation of a new generation of cutters, referred to as thermo-gas jet cutters, is based on the principle of the destructive action of a hot, fast-moving, chemically active jet on the material to be cut.« less

Backflows by active galactic nuclei jets: global properties and influence on supermassive black hole accretion

NASA Astrophysics Data System (ADS)

Cielo, S.; Antonuccio-Delogu, V.; Silk, J.; Romeo, A. D.

2017-06-01

Jets from active galactic nuclei (AGN) inflate large cavities in the hot gas environment around galaxies and galaxy clusters. The large-scale gas circulation promoted within such cavities by the jet itself gives rise to backflows that propagate back to the centre of the jet-cocoon system, spanning all the physical scales relevant for the AGN. Using an adaptive mesh refinement code, we study these backflows through a series of numerical experiments, aiming at understanding how their global properties depend on jet parameters. We are able to characterize their mass flux down to a scale of a few kiloparsecs to about 0.5 M⊙ yr-1 for as long as 15 or 20 Myr, depending on jet power. We find that backflows are both spatially coherent and temporally intermittent, independently of jet power in the range 1043-1045 erg s-1. Using the mass flux thus measured, we model analytically the effect of backflows on the central accretion region, where a magnetically arrested disc lies at the centre of a thin circumnuclear disc. Backflow accretion on to the disc modifies its density profile, producing a flat core and tail. We use this analytic model to predict how accretion beyond the black hole magnetopause is modified, and thus how the jet power is temporally modulated. Under the assumption that the magnetic flux stays frozen in the accreting matter, and that the jets are always launched via the Blandford-Znajek mechanism, we find that backflows are capable of boosting the jet power up to tenfold during relatively short time episodes (a few Myr).

Cryogenic and Simulated Fuel Jet Breakup in Argon, Helium and Nitrogen Gas Flows

NASA Technical Reports Server (NTRS)

Ingebo, Robert D.

1995-01-01

Two-phase flow atomization of liquid nitrogen jets was experimentally investigated. They were co-axially injected into high-velocity gas flows of helium, nitrogen and argon, respectively, and atomized internally inside a two-fluid fuel nozzle. Cryogenic sprays with relatively high specific surface areas were produced, i.e., ratios of surface area to volume were fairly high. This was indicated by values of reciprocal Sauter mean diameters, RSMD's, as measured with a scattered- light scanning instrument developed at NASA Lewis Research Center. Correlating expressions were derived for the three atomizing gases over a gas temperature range of 111 to 422 K. Also, the correlation was extended to include waterjet breakup data that had been previously obtained in simulating fuel jet breakup in sonic velocity gas flow. The final correlating expression included a new dimensionless molecular-scale acceleration group. It was needed to correlate RSMD data, for LN2 and H2O sprays, with the fluid properties of the liquid jets and atomizing gases used in this investigation.

Novel characterization of the aerosol and gas-phase composition of aerosolized jet fuel.

PubMed

Tremblay, Raphael T; Martin, Sheppard A; Fisher, Jeffrey W

2010-04-01

Few robust methods are available to characterize the composition of aerosolized complex hydrocarbon mixtures. The difficulty in separating the droplets from their surrounding vapors and preserving their content is challenging, more so with fuels, which contain hydrocarbons ranging from very low to very high volatility. Presented here is a novel method that uses commercially available absorbent tubes to measure a series of hydrocarbons in the vapor and droplets from aerosolized jet fuels. Aerosol composition and concentrations were calculated from the differential between measured total (aerosol and gas-phase) and measured gas-phase concentrations. Total samples were collected directly, whereas gas-phase only samples were collected behind a glass fiber filter to remove droplets. All samples were collected for 1 min at 400 ml min(-1) and quantified using thermal desorption-gas chromatography-mass spectrometry. This method was validated for the quantification of the vapor and droplet content from 4-h aerosolized jet fuel exposure to JP-8 and S-8 at total concentrations ranging from 200 to 1000 mg/m(3). Paired samples (gas-phase only and total) were collected every approximately 40 min. Calibrations were performed with neat fuel to calculate total concentration and also with a series of authentic standards to calculate specific compound concentrations. Accuracy was good when compared to an online GC-FID (gas chromatography-flame ionization detection) technique. Variability was 15% or less for total concentrations, the sum of all gas-phase compounds, and for most specific compound concentrations in both phases. Although validated for jet fuels, this method can be adapted to other hydrocarbon-based mixtures.

Interaction of a liquid jet with an oncoming gas stream

NASA Astrophysics Data System (ADS)

Koval', M. A.; Shvets, A. I.

1987-06-01

Wind-tunnel tests were carried out to study the interaction between water jets issuing from various types of nozzles (including cylindrical) and subsonic and supersonic air streams with Mach numbers from 0.3 to 3 and Reynolds numbers from 1 x 10 to the 6th to 3 x 10 to the 7th. The following interaction structure was observed: (1) at moderate outflow velocities, the liquid jet has an extended region, which subsequently expands abruptly as a spherical or mushroom-shaped drop; (2) this drop is atomized in the peripheral region and is carried away as a gas-liquid mixture; (3) a shock wave is formed in front of the jet in the oncoming supersonic stream; and (4) a separated flow region is present in the vicinity of the cylindrical nozzle section.

Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tie, W., E-mail: twh.110.666@163.com, E-mail: 84470220@qq.com; Xi'an Jiaotong University, Xi'an 710049; Liu, S.

The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 10{sup 6 }cm/s. The electron temperature decreased from 2.0 eVmore » to 1.3 eV, and the electron density increased from 3.1 × 10{sup 15}/cm{sup 3} to 6.3 × 10{sup 15}/cm{sup 3} at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.« less

Shock-wave proton acceleration from a hydrogen gas jet

NASA Astrophysics Data System (ADS)

Cook, Nathan; Pogorelsky, Igor; Polyanskiy, Mikhail; Babzien, Marcus; Tresca, Olivier; Maharjan, Chakra; Shkolnikov, Peter; Yakimenko, Vitaly

2013-04-01

Typical laser acceleration experiments probe the interaction of intense linearly-polarized solid state laser pulses with dense metal targets. This interaction generates strong electric fields via Transverse Normal Sheath Acceleration and can accelerate protons to high peak energies but with a large thermal spectrum. Recently, the advancement of high pressure amplified CO2 laser technology has allowed for the creation of intense (10^16 Wcm^2) pulses at λ˜10 μm. These pulses may interact with reproducible, high rep. rate gas jet targets and still produce plasmas of critical density (nc˜10^19 cm-3), leading to the transference of laser energy via radiation pressure. This acceleration mode has the advantage of producing narrow energy spectra while scaling well with pulse intensity. We observe the interaction of an intense CO2 laser pulse with an overdense hydrogen gas jet. Using two pulse optical probing in conjunction with interferometry, we are able to obtain density profiles of the plasma. Proton energy spectra are obtained using a magnetic spectrometer and scintillating screen.

Transient and translating gas jet modeling for pressure gain combustion applications

NASA Astrophysics Data System (ADS)

Wijeyakulasuriya, Sameera Devsritha

Major mechanisms governing the mixing process of a gas injected into a long confined chamber is analyzed when there's a relative motion between the two. Such applications arise in a wave rotor combustor (WRCVC) where the moving combustion chambers receive gas from stationary injectors for fueling and ignition. Counter rotating vortices govern the mixing process in such problems, which moves across the channel enhancing mixing. The actions of vortices were seen to localize the injected gas in the vicinity of the injector end wall which can prove advantages during fueling to make a rich mixture near the ignition source and during hot gas injection for ignition to minimize the drop of temperature. The vortex structures can alter the exit conditions of the injector due to its strong near field interactions. The confinement is also important in which it suppresses the development and motion of such vortices and hence affect mixing. The thesis discusses several important features in a WRCVC. Namely, the effect of a combustion channel being opened to the preceding exit port prior to its opening to the gas injectors, on mixing of injected gas with channel gases. This prior opening was seen to deposit vorticity on the channel wall which gets convected along them. This convecting vorticity resulted in enhanced jet penetration. The effect of combustible mixture non-uniformity on ignition success of a WRCVC was also analyzed using 2D and 1D computations. The predictions are validated against measured data from a WRCVC test rig. Ignition locations and combustion pressures were successfully predicted. Limited 3D computations of the hot gas jet mixing with the channel gases were carried out and measure temperature data from the WRCVC test rig was used to verify the axial penetration predictions of the jet. A methodology is proposed to quantify the level of mixing and ignition success by comparing the amount of injected gas inside the channel which is above a certain threshold

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1993-01-01

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1993-10-26

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

Shock wave calibration of under-expanded natural gas fuel jets

NASA Astrophysics Data System (ADS)

White, T. R.; Milton, B. E.

2008-10-01

Natural gas, a fuel abundant in nature, cannot be used by itself in conventional diesel engines because of its low cetane number. However, it can be used as the primary fuel with ignition by a pilot diesel spray. This is called dual-fuelling. The gas may be introduced either into the inlet manifold or, preferably, directly into the cylinder where it is injected as a short duration, intermittent, sonic jet. For accurate delivery in the latter case, a constant flow-rate from the injector is required into the constantly varying pressure in the cylinder. Thus, a sonic (choked) jet is required which is generally highly under-expanded. Immediately at the nozzle exit, a shock structure develops which can provide essential information about the downstream flow. This shock structure, generally referred to as a “barrel” shock, provides a key to understanding the full injection process. It is examined both experimentally and numerically in this paper.

Effects of Mean Flow Profiles on the Instability of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Vedantam, NandaKishore; Parthasarathy, Ramkumar N.

2004-01-01

The effects of the mean velocity profiles on the instability characteristics in the near-injector region of axisymmetric low density gas jets injected vertically upwards into a high-density gas medium were investigated using linear inviscid stability analysis. The flow was assumed to be isothermal and locally parallel. Three velocity profiles, signifying different changes in the mean velocity in the shear layer, were used in the analysis. The effects of the inhomogeneous shear layer and the Froude number (signifying the effects of gravity) on the instability for each set of mean profiles were delineated. At a large Froude number (negligible gravity), a critical density ratio was found for the three profiles at which the jet became absolutely unstable. The critical density ratio for each velocity profile was increased as the Froude number was reduced. A critical Froude number was found for the three sets of profiles, below which the jet was absolutely unstable for all the density ratios less than unity, which demarcated the jet flow into the momentum-driven regime and the buoyancy-driven regime.

Effects of Mean Flow Profiles on Instability of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Vedantam, Nanda Kishore

2003-01-01

The objective of this study was to investigate the effects of the mean flow profiles on the instability characteristics in the near-injector region of low-density gas jets injected into high-density ambient gas mediums. To achieve this, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round gas jet injected vertically upwards into a high-density ambient gas were performed by assuming three different sets of mean velocity and density profiles. The flow was assumed to be isothermal and locally parallel. Viscous and diffusive effects were ignored. The mean flow parameters were represented as the sum of the mean value and a small normal-mode fluctuation. A second order differential equation governing the pressure disturbance amplitude was derived from the basic conservation equations. The first set of mean velocity and density profiles assumed were those used by Monkewitz and Sohn for investigating absolute instability in hot jets. The second set of velocity and density profiles assumed for this study were the ones used by Lawson. And the third set of mean profiles included a parabolic velocity profile and a hyperbolic tangent density profile. The effects of the inhomogeneous shear layer and the Froude number (signifying the effects of gravity) on the temporal and spatio-temporal results for each set of mean profiles were delineated. Additional information is included in the original extended abstract.

Numerical Analysis of an Impinging Jet Reactor for the CVD and Gas-Phase Nucleation of Titania

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.; Stewart, Gregory D.; Collins, Joshua; Rosner, Daniel E.

1994-01-01

We model a cold-wall atmospheric pressure impinging jet reactor to study the CVD and gas-phase nucleation of TiO2 from a titanium tetra-iso-propoxide (TTIP)/oxygen dilute source gas mixture in nitrogen. The mathematical model uses the computational code FIDAP and complements our recent asymptotic theory for high activation energy gas-phase reactions in thin chemically reacting sublayers. The numerical predictions highlight deviations from ideality in various regions inside the experimental reactor. Model predictions of deposition rates and the onset of gas-phase nucleation compare favorably with experiments. Although variable property effects on deposition rates are not significant (approximately 11 percent at 1000 K), the reduction rates due to Soret transport is substantial (approximately 75 percent at 1000 K).

Enhanced electron yield from laser-driven wakefield acceleration in high-Z gas jets.

PubMed

Mirzaie, Mohammad; Hafz, Nasr A M; Li, Song; Liu, Feng; He, Fei; Cheng, Ya; Zhang, Jie

2015-10-01

An investigation of the electron beam yield (charge) form helium, nitrogen, and neon gas jet plasmas in a typical laser-plasma wakefield acceleration experiment is carried out. The charge measurement is made by imaging the electron beam intensity profile on a fluorescent screen into a charge coupled device which was cross-calibrated with an integrated current transformer. The dependence of electron beam charge on the laser and plasma conditions for the aforementioned gases are studied. We found that laser-driven wakefield acceleration in low Z-gas jet targets usually generates high-quality and well-collimated electron beams with modest yields at the level of 10-100 pC. On the other hand, filamentary electron beams which are observed from high-Z gases at higher densities reached much higher yields. Evidences for cluster formation were clearly observed in the nitrogen gas jet target, where we received the highest electron beam charge of ∼1.7 nC. Those intense electron beams will be beneficial for the applications on the generation of bright X-rays, gamma rays radiations, and energetic positrons via the bremsstrahlung or inverse-scattering processes.

Active Chevrons for Jet Noise Reduction

NASA Technical Reports Server (NTRS)

Depuru-Mohan, N. K.; Doty, M. J.

2017-01-01

Jet noise is often a dominant component of aircraft noise, particularly at takeoff. To meet the stringent noise regulations, the aircraft industry is in a pressing need of advanced noise reduction concepts. In the present study, the potential of piezoelectrically-activated chevrons for jet noise reduction was experimentally investigated. The perturbations near the nozzle exit caused by piezoelectrically-activated chevrons could be used to modify the growth rate of the mixing layer and thereby potentially reduce jet noise. These perturbations are believed to increase the production of small-scale disturbances at the expense of large-scale turbulent structures. These large-scale turbulent structures are responsible for the dominant portion of the jet mixing noise, particularly low-frequency noise. Therefore, by exciting the static chevron geometry through piezoelectric actuators, an additional acoustic benefit could possibly be achieved. To aid in the initial implementation of this concept, several flat-faced faceted nozzles (four, six, and eight facets) were investigated. Among the faceted nozzles, it was found that the eight-faceted nozzle behaves very similarly to the round nozzle. Furthermore, among the faceted nozzles with static chevrons, the four-faceted nozzle with static chevrons was found to be most effective in terms of jet noise reduction. The piezoelectrically-activated chevrons reduced jet noise up to 2 dB compared to the same nozzle geometry without excitation. This benefit was observed over a wide range of excitation frequencies by applying very low voltages to the piezoelectric actuators.

An infrared jet in Centaurus A (NGC 5128): Evidence for interaction between the active nucleus and the interstellar medium

NASA Technical Reports Server (NTRS)

Joy, Marshall; Harvey, P. M.; Tollestrup, E. V.; Mcgregor, P. J.; Hyland, A. R.

1990-01-01

In the present study, higher resolution near infrared images of the visually-obscured central region of Centaurus A were obtained in order to investigate the effects of the active nucleus on the surrounding galaxy. Researchers present J(1.25 microns), H(1.65 microns), and K(2.2 microns) images of the central 40 seconds of the galaxy, taken with the Univ. of Texas InSb array camera on the Anglo Australian 3.9 meter telescope. These images reveal a jet extending approx. 10 arcseconds to the northeast of the nucleus at the same position angle as the x ray and radio jets. The infrared jet is most prominent at the shortest wavelength (1.25 microns), where its brightness surpasses that of the nucleus. The blue appearance of the infrared jet is remarkable considering the heavy obscuration that is evident at visual wavelengths. The amount of reddening in the vicinity of the jet is determined from the measured colors of the stellar core of the galaxy, and this value is used to generate an extinction-corrected energy distribution. In contrast to previously studied optical and infrared jets in active nuclei, the short-wavelength prominence of the Cen A jet indicates that it cannot be attributed to synchrotron emission from a beam of relativistic electrons. The remaining viable mechanisms involve an interaction between the interstellar medium and the active nucleus: the infrared radiation from the jet may be due to emission from interstellar gas that has been entrained and heated by the flow of relativistic particles from the nucleus; alternatively, luminous blue stars may have been created by compression of interstellar material by the relativistic plasma. To investigate these proposed mechanisms, near-infrared spectroscopic studies of Cen A are in progress to look for collisionally excited molecular hydrogen emission lines and recombination lines from ionized gas.

Effect of Shrouding Gas Temperature on Characteristics of a Supersonic Jet Flow Field with a Shrouding Laval Nozzle Structure

NASA Astrophysics Data System (ADS)

Liu, Fuhai; Sun, Dongbai; Zhu, Rong; Li, Yilin

2018-05-01

Coherent jet technology was been widely used in the electric arc furnace steelmaking process to protect the kinetic energy of supersonic oxygen jets and achieve a better mixing effect. For this technology, the total temperature distribution of the shrouding jet has a great impact on the velocity of the main oxygen jet. In this article, a supersonic shrouding nozzle using a preheating shrouding jet is proposed to increase the shrouding jet velocity. Both numerical simulation and experimental studies were carried out to analyze its effect on the axial velocity, total temperature and turbulence kinetic energy profiles of the main oxygen jet. Based on these results, it was found that a significant amount of kinetic energy was removed from the main oxygen jet when it passed though the shock wave using a high-temperature shrouding jet, which made the average axial velocity of the coherent jet lower than for a conventional jet in the potential core region. However, the supersonic shrouding nozzle and preheating technology employed for this nozzle design significantly improved the shrouding gas velocity, forming a low-density gas zone at the exit of the main oxygen jet and prolonging the velocity potential core length.

X-ray burst studies with the JENSA gas jet target

NASA Astrophysics Data System (ADS)

Schmidt, Konrad; Chipps, Kelly A.; Ahn, Sunghoon; Allen, Jacob M.; Ayoub, Sara; Bardayan, Daniel W.; Blackmon, Jeffrey C.; Blankstein, Drew; Browne, Justin; Cha, Soomi; Chae, Kyung YUK; Cizewski, Jolie; Deibel, Catherine M.; Deleeuw, Eric; Gomez, Orlando; Greife, Uwe; Hager, Ulrike; Hall, Matthew R.; Jones, Katherine L.; Kontos, Antonios; Kozub, Raymond L.; Lee, Eunji; Lepailleur, Alex; Linhardt, Laura E.; Matos, Milan; Meisel, Zach; Montes, Fernando; O'Malley, Patrick D.; Ong, Wei Jia; Pain, Steven D.; Sachs, Alison; Schatz, Hendrik; Schmitt, Kyle T.; Smith, Karl; Smith, Michael S.; Soares de Bem, Natã F.; Thompson, Paul J.; Toomey, Rebecca; Walter, David

2018-01-01

When a neutron star accretes hydrogen and helium from the outer layers of its companion star, thermonuclear burning enables the αp-process as a break out mechanism from the hot CNO cycle. Model calculations predict (α, p) reaction rates significantly affect both the light curves and elemental abundances in the burst ashes. The Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target enables the direct measurement of previously inaccessible (α,p) reactions with radioactive beams provided by the rare isotope re-accelerator ReA3 at the National Superconducting Cyclotron Laboratory (NSCL), USA. JENSA is going to be the main target for the Recoil Separator for Capture Reactions (SECAR) at the Facility for Rare Isotope Beams (FRIB). Commissioning of JENSA and first experiments at Oak Ridge National Laboratory (ORNL) showed a highly localized, pure gas target with a density of ˜1019 atoms per square centimeter. Preliminary results are presented from the first direct cross section measurement of the 34Ar(α, p)37 K reaction at NSCL.

The influence of surface-active agents in gas mixture on the intensity of jet condensation

NASA Astrophysics Data System (ADS)

Yezhov, YV; Okhotin, VS

2017-11-01

The report presents: the methodology of calculation of contact condensation of steam from the steam-gas mixture into the stream of water, taking into account: the mass flow of steam through the boundary phase, particularly the change in turbulent transport properties near the interface and their connection to the interface perturbations due to the surface tension of the mixture; the method of calculation of the surface tension at the interface water - a mixture of fluorocarbon vapor and water, based on the previously established analytical methods we calculate the surface tension for simple one - component liquid-vapor systems. The obtained analytical relation to calculate the surface tension of the mixture is a function of temperature and volume concentration of the fluorocarbon gas in the mixture and is true for all sizes of gas molecules. On the newly created experimental stand is made verification of experimental studies to determine the surface tension of pure substances: water, steam, C3F8 pair C3F8, produced the first experimental data on surface tension at the water - a mixture of water vapor and fluorocarbon C3F8. The obtained experimental data allow us to refine the values of the two constants used in the calculated model of the surface tension of the mixture. Experimental study of jet condensation was carried out with the flow in the zone of condensation of different gases. The condensation process was monitored by measurement of consumption of water flowing from the nozzle, and the formed condensate. When submitting C3F8, there was a noticeable, intensification condensation process compared with the condensation of pure water vapor. The calculation results are in satisfactory agreement with the experimental data on surface tension of the mixture and steam condensation from steam-gas mixture. Analysis of calculation results shows that the presence of surfactants in the condensation zone affects the partial vapor pressure on the interfacial surface, and

The complex of optical methods for study of gas-liquid jets

NASA Astrophysics Data System (ADS)

Poplavski, S. V.; Boiko, V. M.

2017-10-01

A set of optical methods for studying the dispersion and dynamics of liquids in high-speed gas jets was realized. Four optical methods were used: shadow imaging, PIV method, Laser Doppler Anemometer (LDA), a method for recording the dispersity of a spray by angular scattering of light. With the example of a supersonic coaxial jet with a central fluid supply, a technique is developed that makes it possible to obtain not only the sum of the data by four methods but new critical data on the structure of the two-phase flow, such as the concentration distributions of the spray.

Gas mixing enhanced by power modulations in atmospheric pressure microwave plasma jet

NASA Astrophysics Data System (ADS)

Voráč, J.; Potočňáková, L.; Synek, P.; Hnilica, J.; Kudrle, V.

2016-04-01

Microwave plasma jet operating in atmospheric pressure argon was power modulated by audio frequency sine envelope in the 102 W power range. Its effluent was imaged using interference filters and ICCD camera for several different phases of the modulating signal. The combination of this fast imaging with spatially resolved optical emission spectroscopy provides useful insights into the plasmachemical processes involved. Phase-resolved schlieren photography was performed to visualize the gas dynamics. The results show that for higher modulation frequencies the plasma chemistry is strongly influenced by formation of transient flow perturbation resembling a vortex during each period. The perturbation formation and speed are strongly influenced by the frequency and power variations while they depend only weakly on the working gas flow rate. From application point of view, the perturbation presence significantly broadened lateral distribution of active species, effectively increasing cross-sectional area suitable for applications.

Coronal Jets from Minifilament Eruptions in Active Regions

NASA Technical Reports Server (NTRS)

Martinez, Francisco; Sterling, Alphonse C.; Falconer, David A.; Moore, Ronald L.

2016-01-01

Solar coronal jets are transient (frequently of lifetime approx.10 min) features that shoot out from near the solar surface, become much longer than their width, and occur in all solar regions, including coronal holes, quiet Sun, and active regions (e.g., Shimojo et al. 1996, Cirtain et al. 2007). Sterling et al. (2015) and other studies found that in coronal holes and in quiet Sun the jets result when small-scale filaments, called "minifilaments" erupt onto nearby open or high-reaching field lines. Additional studies found that coronal-jet-onset locations (and hence presumably the minifilament-eruption-onset locations) coincided with locations of magnetic-flux cancelation. For active region (AR) jets however the situation is less clear. Sterling et al. (2016) studied jets in one active region over a 24-hour period; they found that some AR jets indeed resulted from minifilament eruptions, usually originating from locations of episodes of magnetic-flux cancelation. In some cases however they could not determine whether flux was emerging or canceling at the polarity inversion line from which the minifilament erupted, and for other jets of that region minifilaments were not conclusively apparent prior to jet occurrence. Here we further study AR jets, by observing them in a single AR over a one-week period, using X-ray images from Hinode/XRT and EUV/UV images from SDO/AIA, and line-of-sight magnetograms and white-light intensity-grams from SDO/HMI. We initially identified 13 prominent jets in the XRT data, and examined corresponding AIA and HMI data. For at least several of the jets, our findings are consistent with the jets resulting from minifilament eruptions, and originating from sites of magnetic-field cancelation.

Coronal Jets from Minifilament Eruptions in Active Regions

NASA Astrophysics Data System (ADS)

Sterling, A. C.; Martinez, F.; Falconer, D. A.; Moore, R. L.

2016-12-01

Solar coronal jets are transient (frequently of lifetime 10 min) features that shoot out from near the solar surface, become much longer than their width, and occur in all solar regions, including coronal holes, quiet Sun, and active regions (e.g., Shimojo et al. 1996, Certain et al. 2007). Sterling et al. (2015) and other studies found that in coronal holes and in quiet Sun the jets result when small-scale filaments, called ``minifilaments,'' erupt onto nearby open or high-reaching field lines. Additional studies found that coronal-jet-onset locations (and hence presumably the minifilament-eruption-onset locations) coincided with locations of magnetic-flux cancellation. For active region (AR) jets however the situation is less clear. Sterling et al. (2016) studied jets in one active region over a 24-hour period; they found that some AR jets indeed resulted from minifilament eruptions, usually originating from locations of episodes of magnetic-flux cancelation. In some cases however they could not determine whether flux was emerging or canceling at the polarity inversion line from which the minifilament erupted; and for other jets of that region minifilaments were not conclusively apparent prior to jet occurrence. Here we further study AR jets, by observing them in a single AR over a one-week period, using X-ray images from Hinode/XRT and EUV/UV images from SDO/AIA, and line-of-sight magnetograms and white-light intensity-grams from SDO/HMI. We initially identified 13 prominent jets in the XRT data, and examined corresponding AIA and HMI data. For at least several of the jets, our findings are consistent with the jets resulting from minifilament eruptions, and originating from sights of magnetic-field cancelation. Thus our findings support that, at least in many cases, AR coronal jets result from the same physical processes that produce coronal jets in quiet-Sun and coronal-hole regions. FM was supportedby the Research Experience for Undergraduates (REU) program at

Jet activity in the symbiotic variable R Aquarii

NASA Technical Reports Server (NTRS)

Michalitsianos, A. G.; Hollis, J. M.; Kafatos, M.

1986-01-01

Low-resolution ultraviolet spectra of the R Aquarii jet have been obtained with the International Ultraviolet Explorer (IUE). The most recent IUE observations indicate the ionization state of the jet is increasing. Subarcsecond, Very Large Array observations of R Aquarii have resolved the radio-continuum structure into discrete parcels of emission that are extended and nearly collinear. R Aquarii provides evidence that indicates stellar jet activity is not unique to objects associated with high-energy emission processes alone. Rather, the nature of the aligned radio-optical features that comprise the R Aquarii jet indicate that directional mass expulsion, in the form of discrete-collimated ejecta, probably reflect a general, underlying, physical process associated with a wide variety of peculiar stellar objects. As such, the R Aquarii jet constitutes a prototype for jet activity in composite or peculiar emission stars.

Glimpsing the Structure and Dynamics of the Plume's Evolving Gas Jets with INMS: A Look Back at Cassini's Decade Long Tour of Enceladus

NASA Astrophysics Data System (ADS)

Teolis, B. D.; Perry, M. E.; Waite, J. H., Jr.

2017-12-01

Throughout the Cassini spacecraft's multi-decade tour of Saturn's geologically active icy satellite Enceladus ,the Ion Neutral Mass Spectrometer (INMS) has sampled the gas density and distribution during multiple flyby traversals through the south polar gas/ice plumes: two (E3 and E5) at high (hundreds of km) altitude and five (E7, E14, E17 and E21) at low (90, 66, 66, 41 km) altitude. These measurements, spanning seven years, have enabled changes over time to be observed by INMS. Now that Cassini has concluded its mission, we present our most comprehensive analysis and modeling so far of the plume density and structure from INMS data on all of the flybys, including time variability in the continuous and discrete gas sources and jets along the tiger stripes. We estimate maximum plume water vapor densities of 6, 3 and 6 ×1014 H2O/m3 from INMS data acquired along the E17, E17 and E18 trajectories, respectively. The INMS data are consistent with (1) simultaneous slow isotropic and super-sonic gas emission in the gas jets, and (2) stochastic variability (up to a factor ten) in the source rates and intensities of individual jets. The total plume source rate also appears to vary stochastically between flybys, ranging between 200 and 1000 kg/s, with a systematic variation with Enceladus' orbital position possible (though unconfirmed) in INMS data. Together with Cassini's other instruments [Teolis et al, Astrobiology, in press] these INMS results indicate Enceladus to be a highly active and dynamic ocean world.

Smashing a Jet into a Cloud to Form Stars

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-12-01

What happens when the highly energetic jet from the center of an active galaxy rams into surrounding clouds of gas and dust? A new study explores whether this might be a way to form stars.The authors simulations at an intermediate (top) and final (bottom) stage show the compression in the gas cloud as a jet (red) enters from the left. Undisturbed cloud material is shown in blue, whereas green corresponds to cold, compressed gas actively forming stars. [Fragile et al. 2017]Impacts of FeedbackCorrelation between properties of supermassive black holes and their host galaxies suggest that there is some means of communication between them. For this reason, we suspect that feedback from an active galactic nucleus (AGN) in the form of jets, for instance controls the size of the galaxy by influencing star formation. But how does this process work?AGN feedback can be either negative or positive. In negative feedback, the gas necessary for forming stars is heated or dispersed by the jet, curbing or halting star formation. In positive feedback, jets propagate through the surrounding gas with energies high enough to create compression in the gas, but not so high that they heat it. The increased density can cause the gas to collapse, thereby triggering star formation.In a recent study, a team of scientists led by Chris Fragile (College of Charleston) modeled what happens when an enormous AGN jet slams into a dwarf-galaxy-sized, inactive cloud of gas. In particular, the team explored the possibility of star-forming positive feedback with the goal of reproducing recent observations of something called Minkowskis Object, a stellar nursery located at the endpoint of a radio jet emitted from the active galaxy NGC 541.The star formation rate in the simulated cloud increases dramatically as a result of the jets impact, reaching the rate currently observed for Minkowskis Objects within 20 million years. [Fragile et al. 2017]Triggering Stellar BirthFragile and collaborators used a

Gas flow rate dependence of the discharge characteristics of a helium atmospheric pressure plasma jet interacting with a substrate

NASA Astrophysics Data System (ADS)

Yan, Wen; Economou, Demetre J.

2017-10-01

A 2D (axisymmetric) computational study of the discharge characteristics of an atmospheric pressure plasma jet as a function of gas flow rate was performed. The helium jet emerged from a dielectric tube, with an average gas flow velocity in the range 2.5-20 m s-1 (1 atm, 300 K) in a nitrogen ambient, and impinged on a substrate a short distance dowstream. The effect of the substrate conductivity (conductror versus insulator) was also studied. Whenever possible, simulation predictions were compared with published experimental observations. Discharge ignition and propagation in the dielectric tube were hardly affected by the He gas flow velocity. Most properties of the plasma jet, however, depended sensitively on the He gas flow velocity, which determined the concentration distributions of helium and nitrogen in the mixing layer forming in the gap between the tube exit and the substrate. At low gas flow velocity, the plasma jet evolved from a hollow (donut-shaped) feature to one where the maximum of electron density was on axis. When the gas flow velocity was high, the plasma jet maintained its hollow structure until it struck the substrate. For a conductive substrate, the radial ion fluxes to the surface were relatively uniform over a radius of ~0.4-0.8 mm, and the dominant ion flux was that of He+. For a dielectric substrate, the radial ion fluxes to the surface peaked on the symmetry axis at low He gas flow velocity, but a hollow ion flux distribution was observed at high gas flow velocity. At the same time, the main ion flux switched from N2+ to He2+ as the He gas flow velocity increased from a low to a high value. The diameter of the plasma ‘footprint’ on the substrate first increased with increasing He gas flow velocity, and eventually saturated with further increases in velocity.

Schlieren flow visualization of helium atmospheric plasma jet and influence of the gas flow rate and applied voltage frequency

NASA Astrophysics Data System (ADS)

Borghei, S. M.; Vaziri, N.; Alibabaei, S.

2018-03-01

We used schlieren photography to visualize the influence of gas flow rates of 1, 2.5, 5, 10 L/min and of the applied voltage frequency on a helium atmospheric plasma jet induced at the nozzle of a capillary tube. The expansion of the gas in the surrounding medium (air) was analyzed in the two different modes – plasma on/plasma off. Changes in the above parameters affect the gas flow regime and the hydrodynamics of the jet.

Three-dimensional computer simulation of non-reacting jet-gas flow mixing in an MHD second stage combustor

NASA Astrophysics Data System (ADS)

Chang, S. L.; Lottes, S. A.; Berry, G. F.

Argonne National Laboratory is investigating the non-reacting jet-gas mixing patterns in a magnetohydrodynamics (MHD) second stage combustor by using a three-dimensional single-phase hydrodynamics computer program. The computer simulation is intended to enhance the understanding of flow and mixing patterns in the combustor, which in turn may improve downstream MHD channel performance. The code is used to examine the three-dimensional effects of the side walls and the distributed jet flows on the non-reacting jet-gas mixing patterns. The code solves the conservation equations of mass, momentum, and energy, and a transport equation of a turbulence parameter and allows permeable surfaces to be specified for any computational cell.

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.

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.

Effect of Nozzle Geometry on Characteristics of Submerged Gas Jet and Bubble Noise.

PubMed

Bie, Hai-Yan; Ye, Jian-Jun; Hao, Zong-Rui

2016-10-01

Submerged exhaust noise is one of the main noise sources of underwater vehicles. The nozzle features of pipe discharging systems have a great influence on exhaust noise, especially on the noise produced by gas-liquid two-phase flow outside the nozzle. To study the influence of nozzle geometry on underwater jet noises, a theoretical study was performed on the critical weber number at which the jet flow field morphology changes. The underwater jet noise experiments of different nozzles under various working conditions were carried out. The experimental results implied that the critical weber number at which the jet flow transformed from bubbling regime to jetting regime was basically identical with the theoretical analysis. In the condition of jetting regime, the generated cavity of elliptical and triangular nozzles was smaller than that of the circular nozzle, and the middle- and high-frequency bands increased nonlinearly. The radiated noise decreased with the decrease in nozzle diameter. Combined with theoretical analysis and experimental research, three different submerged exhaust noise reduction devices were designed, and the validation tests proved that the noise reduction device with folds and diversion cone was the most effective. © 2015 Society for Laboratory Automation and Screening.

Eruptions that Drive Coronal Jets in a Solar Active Region

NASA Technical Reports Server (NTRS)

Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

2016-01-01

Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

Predicted exhaust emissions from a methanol and jet fueled gas turbine combustor

NASA Technical Reports Server (NTRS)

Adelman, H. G.; Browning, L. H.; Pefley, R. K.

1975-01-01

A computer model of a gas turbine combustor has been used to predict the kinetic combustion and pollutant formation processes for methanol and simulated jet fuel. Use of the kinetic reaction mechanisms has also allowed a study of ignition delay and flammability limit of these two fuels. The NOX emissions for methanol were predicted to be from 69 to 92% lower than those for jet fuel at the same equivalence ratio which is in agreement with experimentally observed results. The high heat of vaporization of methanol lowers both the combustor inlet mixture temperatures and the final combustion temperatures. The lower combustion temperatures lead to low NOX emissions while the lower inlet mixture temperatures increase methanol's ignition delay. This increase in ignition delay dictates the lean flammability limit of methanol to be 0.8, while jet fuel is shown to combust at 0.4.

Evaluation of the plasma hydrogen isotope content by residual gas analysis at JET and AUG

NASA Astrophysics Data System (ADS)

Drenik, A.; Alegre, D.; Brezinsek, S.; De Castro, A.; Kruezi, U.; Oberkofler, M.; Panjan, M.; Primc, G.; Reichbauer, T.; Resnik, M.; Rohde, V.; Seibt, M.; Schneider, P. A.; Wauters, T.; Zaplotnik, R.; ASDEX-Upgrade, the; EUROfusion MST1 Teams; contributors, JET

2017-12-01

The isotope content of the plasma reflects on the dynamics of isotope changeover experiments, efficiency of wall conditioning and the performance of a fusion device in the active phase of operation. The assessment of the isotope ratio of hydrogen and methane molecules is used as a novel method of assessing the plasma isotope ratios at JET and ASDEX-Upgrade (AUG). The isotope ratios of both molecules in general shows similar trends as the isotope ratio detected by other diagnostics. At JET, the absolute values of RGA signals are in relatively good agreement with each other and with spectroscopy data, while at AUG the deviation from neutral particle analyser data are larger, and the results show a consistent spatial distribution of the isotope ratio. It is further shown that the isotope ratio of the hydrogen molecule can be used to study the degree of dissociation of the injected gas during changeover experiments.

Atmospheric-pressure plasma jet system for silicon etching without fluorocarbon gas feed

NASA Astrophysics Data System (ADS)

Ohtsu, Yasunori; Nagamatsu, Kenta

2018-01-01

We developed an atmospheric-pressure plasma jet (APPJ) system with a tungsten rod electrode coated with C2F4 particles of approximately 0.3 µm diameter for the surface treatment of a silicon wafer. The APPJ was generated by dielectric barrier discharge with a driving frequency of 22 kHz using a He gas flow. The characteristics of the APPJ were examined under various experimental conditions. The plasma jet length increased proportionally to the electric field. It was found that the treatment area of the silicon wafer was approximately 1 mm in diameter. By atomic force microscopy analysis, minute irregularities with a maximum length of about 600 nm and part of a ring-shaped trench were observed. A Si etching rate of approximately 400 nm/min was attained at a low power of 6 W and a He flow rate of 1 L/min without introducing molecular gas including F atoms.

Application of gas cyclone-liquid jet absorption separator for purification of tail gas containing ammonia.

PubMed

Ma, Liang; Zhao, Zhi-Huang; Peng, Lv; Yang, Xue-Jing; Fu, Peng-Bo; Liu, Yi; Huang, Yuan

2018-05-31

In this experiment, with stainless steel gas cyclone-liquid jet absorption separator as carrier, NH 3 as experimental gas, and water and H 3 PO 4 solution as absorbents, corresponding NH 3 absorption rate change is obtained through the adjustment of experimental parameters, such as NH 3 inlet concentration, inlet velocity of mixed gas, injection flow rate of absorbent, temperature of absorbent, and H 3 PO 4 absorbent concentration. The NH 3 absorption rate decreases with the increase in NH 3 inlet concentration and inlet gas velocity. The NH 3 absorption rate will increase first and then tends to remain unchanged after reaching a certain degree with the increase in liquid injection flow rate and absorbent concentration. The NH 3 absorption rate will increase first and then decrease with the increase in the absorbent temperature. The maximum NH 3 removal efficiencies of water and H 3 PO 4 were 96% and 99%, respectively.

Simultaneous velocity measurements of particle and gas phase in particle-laden co-flowing pipe jets

NASA Astrophysics Data System (ADS)

Saridakis, Isaac; Lau, Timothy; Djenidi, Lyazid; Nathan, Graham

2016-11-01

Simultaneous planar velocity measurements of both the carrier gas and particles are reported of well-characterized particle-laden co-flowing pipe jets. It is proposed to present measurements that were obtained through application of a median-filter discrimination technique to separate the Particle Image Velocimetry (PIV) signals of the 0.5 μm diameter fluid tracers from those of the larger particles of diameter 20 μm and 40 μm. Instantaneous particle and fluid planar velocity distributions were measured for three Reynold's numbers ranging from 10,000 to 40,000 and five Stokes numbers from 1 to 22, at a jet bulk fluid velocity to co-flow velocity ratio of 12. Selected results will be presented which show that the slip velocity is dependent on the local Stokes number. These are the first simultaneous carrier gas and particle velocity measurements in particle-laden jets and provide new understanding of fluid-particle interactions. Financial support from Australian Research Council and Australian Renewable Energy Agency.

A combustion model for studying the effects of ideal gas properties on jet noise

NASA Astrophysics Data System (ADS)

Jacobs, Jerin; Tinney, Charles

2016-11-01

A theoretical combustion model is developed to simulate the influence of ideal gas effects on various aeroacoustic parameters over a range of equivalence ratios. The motivation is to narrow the gap between laboratory and full-scale jet noise testing. The combustion model is used to model propane combustion in air and kerosene combustion in air. Gas properties from the combustion model are compared to real lab data acquired at the National Center for Physical Acoustics at the University of Mississippi as well as outputs from NASA's Chemical Equilibrium Analysis code. Different jet properties are then studied over a range of equivalence ratios and pressure ratios for propane combustion in air, kerosene combustion in air and heated air. The findings reveal negligible differences between the three constituents where the density and sound speed ratios are concerned. Albeit, the area ratio required for perfectly expanded flow is shown to be more sensitive to gas properties, relative to changes in the temperature ratio.

Cometary Jet Collimation Without Physical Confinement

NASA Astrophysics Data System (ADS)

Steckloff, Jordan; Melosh, H.

2012-10-01

Recent high-resolution images of comet nuclei reveal that gases and dust expelled by the comet are organized into narrow jets. Contemporary models postulate that these jets collimate when the expanding gases and dust pass through a physical aperture or nozzle [1]. However, recent high-resolution spacecraft observations fail to detect such apertures on cometary surfaces [2]. Additionally, observations of comet nuclei by visiting spacecraft have observed that jet activity is tied to the diurnal rotation of the comet. This suggests that jet emissions are driven by the sun, and therefore must emanate from close to the surface of the comet (order of 10 cm.) Here we describe a simplified computer model of jets emanating from Comet Tempel 1. We approximate the active areas (vents) of the comet as a region of smooth, level terrain on the order of 10 m in width. We assume that each element of the active area is emitting gas molecules with the same spatial distribution, and integrate over the active area in order to calculate the gas drag force. We consider two angular emission profiles (isotropic and lambertian), and assume plane-strain geometry. Uniformly sized particles are placed randomly on the surface of the vent, and their positions in time are tracked. For our simulation, spherical particles with radii of 1 µm to 1 cm were considered. We observe that the overwhelming majority of the particles remain close to the central axis of the active area, forming a well-collimated jet, with particles reaching escape velocity. This mechanism may explain cometary jets, given the physical and observational constraints. References: [1] Yelle R.V. (2004) Icarus 167, 30-36. [2] A’Hearn M.F. et al. (2011) Science 332, 1396-1400. [3] Belton M.J.S. and Melosh H.J. (2009) Icarus 200, 280-291. Acknowledgements: This research is supported by NASA grant PGG NNX10AU88G.

Linear Stability Analysis of Gravitational Effects on a Low-Density Gas Jet Injected into a High-Density Medium

NASA Technical Reports Server (NTRS)

Lawson, Anthony L.; Parthasarathy, Ramkumar N.

2005-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The Briggs-Bers criterion was combined with the spatio-temporal stability analysis to determine the nature of the absolute instability of the jet whether absolutely or convectively unstable. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the absolute instability of the jet were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be.

Time Dependent Navier-Stokes Solution of a Turbulent Gas Jet Ejected from a Rectangular Orifice into a High-Subsonic Crossflow

DTIC Science & Technology

1980-06-01

number, M-U/a • xi Symbol Meani_ n P Pressure of gas mixture. p Property of the gas mixture. Prt Turbulent Prandtl Number, Prt=0.9 Q Jet to freestream...empirical equations defining the jet trajectory can be written in the following general form, x ym n d ’d \\P 0 O2 where K is some prescribed constant...and, m’ 3 and 1 . n < 1.5 For completeness, Lee (Ref 19) and Garner (Ref 20) authored survey reports detailing the. state-of-the-art of Jet-crossflow

Applications of active adaptive noise control to jet engines

NASA Technical Reports Server (NTRS)

Shoureshi, Rahmat; Brackney, Larry

1993-01-01

During phase 2 research on the application of active noise control to jet engines, the development of multiple-input/multiple-output (MIMO) active adaptive noise control algorithms and acoustic/controls models for turbofan engines were considered. Specific goals for this research phase included: (1) implementation of a MIMO adaptive minimum variance active noise controller; and (2) turbofan engine model development. A minimum variance control law for adaptive active noise control has been developed, simulated, and implemented for single-input/single-output (SISO) systems. Since acoustic systems tend to be distributed, multiple sensors, and actuators are more appropriate. As such, the SISO minimum variance controller was extended to the MIMO case. Simulation and experimental results are presented. A state-space model of a simplified gas turbine engine is developed using the bond graph technique. The model retains important system behavior, yet is of low enough order to be useful for controller design. Expansion of the model to include multiple stages and spools is also discussed.

Effect of sheath gas in atmospheric-pressure plasma jet for potato sprouting suppression

NASA Astrophysics Data System (ADS)

Nishiyama, S.; Monma, M.; Sasaki, K.

2016-09-01

Recently, low-temperature atmospheric-pressure plasma jets (APPJs) attract much interest for medical and agricultural applications. We try to apply APPJs for the suppression of potato sprouting in the long-term storage. In this study, we investigated the effect of sheath gas in APPJ on the suppression efficiency of the potato sprouting. Our APPJ was composed of an insulated thin wire electrode, a glass tube, a grounded electrode which was wound on the glass tube, and a sheath gas nozzle which was attached at the end of the glass tube. The wire electrode was connected to a rectangular-waveform power supply at a frequency of 3 kHz and a voltage of +/- 7 kV. Helium was fed through the glass tube, while we tested dry nitrogen, humid nitrogen, and oxygen as the sheath gas. Eyes of potatoes were irradiated by APPJ for 60 seconds. The sprouting probability was evaluated at two weeks after the plasma irradiation. The sprouting probability was 28% when we employed no sheath gases, whereas an improved probability of 10% was obtained when we applied dry nitrogen as the sheath gas. Optical emission spectroscopy was carried out to diagnose the plasma jet. It was suggested that reactive species originated from nitrogen worked for the efficient suppression of the potato sprouting.

Investigation of PVdF active diaphragms for synthetic jets

NASA Astrophysics Data System (ADS)

Bailo, Kelly C.; Brei, Diann E.; Calkins, Frederick T.

2000-06-01

Current research has shown that aircraft can gain significant aerodynamic performance benefits by employing active flow control (AFC). One of the enabling technologies of AFC is the synthetic jet. Synthetic jets, also known as zero-net-mass flux actuators, act as bi-directional pumps injecting high momentum air into the local aerodynamic flow. Previous work has concentrated on high frequency synthetic jets based on piezoelectric active diaphragms such as Thunder actuators. Low frequency synthetic jets present a unique challenge requiring large displacements, which current technology has difficulty meeting. Boeing is investigating novel shaped low frequency synthetic jets that can modify the flow over fixed aircraft wings. This paper present the initial study of two promising active diaphragm concepts: a crescent shape and an opposing bender shape. These active diaphragms were numerically modeled utilizing the general-purpose finite element code ABAQUS. Using the ABAQUS results, the dynamic volume change within each jet was calculated and incorporated into an analytical linear Bernoulli model to predict the velocities and pressures at the nozzle. Simulations were performed to determine trends to assist in selection of prototype configurations. Prototypes of both diaphragm concepts were constructed from polyvinylidene fluoride and experimentally tested at Boeing with promising results.

Deflection of jets induced by jet-cloud and jet-galaxy interactions

NASA Astrophysics Data System (ADS)

Mendoza, S.; Longair, M. S.

2001-06-01

The model first introduced by Raga & Cantó in which astrophysical jets are deflected on passing through an isothermal high-density region is generalized by taking into account gravitational effects on the motion of the jet as it crosses the high-density cloud. The problem is also generalized for relativistic jets in which gravitational effects induced by the cloud are neglected. Two further cases, classical and relativistic, are discussed for the cases in which the jet is deflected on passing through the interstellar gas of a galaxy in which a dark matter halo dominates the gravitational potential. The criteria for the stability of jets due to the formation of internal shocks are also discussed.

System and method for crystalline sheet growth using a cold block and gas jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kellerman, Peter L.; Mackintosh, Brian; Carlson, Frederick M.

A crystallizer for growing a crystalline sheet from a melt may include a cold block having a cold block surface that faces an exposed surface of the melt, the cold block configured to generate a cold block temperature at the cold block surface that is lower than a melt temperature of the melt at the exposed surface. The system may also include a nozzle disposed within the cold block and configured to deliver a gas jet to the exposed surface, wherein the gas jet and the cold block are interoperative to generate a process zone that removes heat from themore » exposed surface at a first heat removal rate that is greater than a second heat removal rate from the exposed surface in outer regions outside of the process zone.« less

A Computational Study for the Utilization of Jet Pulsations in Gas Turbine Film Cooling and Flow Control

NASA Technical Reports Server (NTRS)

Kartuzova, Olga V.

2012-01-01

This report is the second part of a three-part final report of research performed under an NRA cooperative Agreement contract. The first part is NASA/CR-2012-217415. The third part is NASA/CR-2012-217417. Jets have been utilized in various turbomachinery applications in order to improve gas turbines performance. Jet pulsation is a promising technique because of the reduction in the amount of air removed from compressor. In this work two areas of pulsed jets applications were computationally investigated using the commercial code Fluent (ANSYS, Inc.); the first one is film cooling of High Pressure Turbine (HPT) blades and second one is flow separation control over Low Pressure Turbine (LPT) airfoil using Vortex Generator Jets (VGJ). Using pulsed jets for film cooling purposes can help to improve the effectiveness and thus allow higher turbine inlet temperature. Effects of the film hole geometry, blowing ratio and density ratio of the jet, pulsation frequency and duty cycle of blowing on the film cooling effectiveness were investigated. As for the low-pressure turbine (LPT) stages, the boundary layer separation on the suction side of airfoils can occur due to strong adverse pressure gradients. The problem is exacerbated as airfoil loading is increased. Active flow control could provide a means for minimizing separation under conditions where it is most severe (low Reynolds number), without causing additional losses under other conditions (high Reynolds number). The effects of the jet geometry, blowing ratio, density ratio, pulsation frequency and duty cycle on the size of the separated region were examined in this work. The results from Reynolds Averaged Navier-Stokes and Large Eddy Simulation computational approaches were compared with the experimental data.

Thermal protection performance of opposing jet generating with solid fuel

NASA Astrophysics Data System (ADS)

Shen, Binxian; Liu, Weiqiang

2018-03-01

A light and small gas supply device, which uses fuel gas generating with solid fuel as coolant gas, is introduced for opposing jet thermal protection in hypersonic vehicles. A numerical study on heat flux reduction in hypersonic flow with opposing jet is conducted to investigate the cooling efficiency of fuel gas. Flow field and cooling efficiency at different jet temperatures, as well as the effect of fuel gas, are determined. Detailed results show that shock stand-off distance changes with an increase in jet pressure ratio and remains constant with an increase in jet temperature. Cooling efficiency weakens with an increase in jet temperature and can be strengthened by enhancing jet pressure. Lastly, a remarkable heat flux reduction is observed with fuel gas injection with respect to no fuel gas injection when jet temperature reaches 900 K, thereby proving the positive cooling efficiency of fuel gas.

Formation of jets in Comet 19P/Borrelly by subsurface geysers

USGS Publications Warehouse

Yelle, R.V.; Soderblom, L.A.; Jokipii, J.R.

2004-01-01

Observations of the inner coma of Comet 19P/Borrelly with the camera on the Deep Space 1 spacecraft revealed several highly collimated dust jets emanating from the nucleus. The observed jets can be produced by acceleration of evolved gas from a subsurface cavity through a narrow orifice to the surface. As long as the cavity is larger than the orifice, the pressure in the cavity will be greater than the ambient pressure in the coma and the flow from the geyser will be supersonic. The gas flow becomes collimated as the sound speed is approached and dust entrainment in the gas flow creates the observed jets. Outside the cavity, the expanding gas loses its collimated character, but the density drops rapidly decoupling the dust and gas, allowing the dust to continue in a collimated beam. The hypothesis proposed here can explain the jets seen in the inner coma of Comet 1P/Halley as well, and may be a primary mechanism for cometary activity. ?? 2003 Published by Elsevier Inc.

How AGN Jets Heat the Intracluster Medium—Insights from Hydrodynamic Simulations

NASA Astrophysics Data System (ADS)

Yang, H.-Y. Karen; Reynolds, Christopher S.

2016-10-01

Feedback from active galactic nuclei (AGNs) is believed to prevent catastrophic cooling in galaxy clusters. However, how the feedback energy is transformed into heat, and how the AGN jets heat the intracluster medium (ICM) isotropically, still remain elusive. In this work, we gain insights into the relative importance of different heating mechanisms using three-dimensional hydrodynamic simulations including cold gas accretion and momentum-driven jet feedback, which are the most successful models to date in terms of reproducing the properties of cool cores. We find that there is net heating within two “jet cones” (within ∼30° from the axis of jet precession) where the ICM gains entropy by shock heating and mixing with the hot thermal gas within bubbles. Outside the jet cones, the ambient gas is heated by weak shocks, but not enough to overcome radiative cooling, therefore, forming a “reduced” cooling flow. Consequently, the cluster core is in a process of “gentle circulation” over billions of years. Within the jet cones, there is significant adiabatic cooling as the gas is uplifted by buoyantly rising bubbles; outside the cones, energy is supplied by the inflow of already-heated gas from the jet cones as well as adiabatic compression as the gas moves toward the center. In other words, the fluid dynamics self-adjusts such that it compensates and transports the heat provided by the AGN, and hence no fine-tuning of the heating profile of any process is necessary. Throughout the cluster evolution, turbulent energy is only at the percent level compared to gas thermal energy, and thus turbulent heating is not the main source of heating in our simulation.

Quartz Crystal Micro-Balance Gas Sensor with Ink-Jet Printed Nano-Diamond Sensitive Layer

NASA Astrophysics Data System (ADS)

Kulha, Pavel; Kroutil, Jiří; Laposa, Alexandr; Procházka, Václav; Husák, Miroslav

2016-01-01

the paper presents fabrication and characterization of a Quartz Crystal Microbalance based gas sensor with a diamond powder sensitive layer deposited using the ink-jet printing technique. The sensor was exposed to a low concentration of ammonia, acetone vapors and different levels of humidity. Impedance characteristics close to the natural resonant frequency of 10 MHz were examined. The sensor exhibits significant shifts in serial resonant frequency under different gas environments.

Worldwide Life Cycle Analysis (LCA) of Greenhouse Gas (GHG) Emissions from Petroleum Jet Fuel

DOT National Transportation Integrated Search

2017-11-09

The main objective of this project was to calculate greenhouse gas emissions estimates for petroleum jet fuels for the recent past and for future scenarios in the coming decades. Results were reported globally and broken out by world regions, and the...

Active control of the jet in coaxial arrangement

NASA Astrophysics Data System (ADS)

Broučková, Z.; Trávníček, Z.; Šafařík, P.

2013-04-01

An axisymmetric jet flow, issuing as a fully developed flow from a long straight pipe at Re = 1600 and 5500, was actively controlled by an annular synthetic jet. The Pitot tube, hot-wire anemometry (CTA) and flow visualization were used for an experimental investigation of the flow control. The working fluid was air. The effect of varying Strouhal number (St = (0.18÷1.94)) on a width and entrainment of the main jet flow was studied. It was found that the main jet is the most sensitive to the actuation at St = 0.28÷0.60 and St = 0.18, for Re = 1600 and Re = 5500, respectively.

Mass spectrometric gas composition measurements associated with jet interaction tests in a high-enthalpy wind tunnel

NASA Technical Reports Server (NTRS)

Lewis, B. W.; Brown, K. G.; Wood, G. M., Jr.; Puster, R. L.; Paulin, P. A.; Fishel, C. E.; Ellerbe, D. A.

1986-01-01

Knowledge of test gas composition is important in wind-tunnel experiments measuring aerothermodynamic interactions. This paper describes measurements made by sampling the top of the test section during runs of the Langley 7-Inch High-Temperature Tunnel. The tests were conducted to determine the mixing of gas injected from a flat-plate model into a combustion-heated hypervelocity test stream and to monitor the CO2 produced in the combustion. The Mass Spectrometric (MS) measurements yield the mole fraction of N2 or He and CO2 reaching the sample inlets. The data obtained for several tunnel run conditions are related to the pressures measured in the tunnel test section and at the MS ionizer inlet. The apparent distributions of injected gas species and tunnel gas (CO2) are discussed relative to the sampling techniques. The measurements provided significant real-time data for the distribution of injected gases in the test section. The jet N2 diffused readily from the test stream, but the jet He was mostly entrained. The amounts of CO2 and Ar diffusing upward in the test section for several run conditions indicated the variability of the combustion-gas test-stream composition.

In-flight imaging of transverse gas jets injected into transonic and supersonic crossflows: Design and development. M.S. Thesis, Mar. 1993

NASA Technical Reports Server (NTRS)

Wang, Kon-Sheng Charles

1994-01-01

The design and development of an airborne flight-test experiment to study nonreacting gas jets injected transversely into transonic and supersonic crossflows is presented. Free-stream/crossflow Mach numbers range from 0.8 to 2.0. Planar laser-induced fluorescence (PLIF) of an iodine-seeded nitrogen jet is used to visualize the jet flow. Time-dependent images are obtained with a high-speed intensified video camera synchronized to the laser pulse rate. The entire experimental assembly is configured compactly inside a unique flight-test-fixture (FTF) mounted under the fuselage of the F-104G research aircraft, which serves as a 'flying wind tunnel' at NASA Dryden Flight Research Center. The aircraft is flown at predetermined speeds and altitudes to permit a perfectly expanded (or slightly underexpanded) gas jet to form just outside the FTF at each free-stream Mach number. Recorded gas jet images are then digitized to allow analysis of jet trajectory, spreading, and mixing characteristics. Comparisons will be made with analytical and numerical predictions. This study shows the viability of applying highly sophisticated groundbased flow diagnostic techniques to flight-test vehicle platforms that can achieve a wide range of thermo/fluid dynamic conditions. Realistic flow environments, high enthalpies, unconstrained flowfields, and moderate operating costs are also realized, in contrast to traditional wind-tunnel testing.

PIV Measurements in Weakly Buoyant Gas Jet Flames

NASA Technical Reports Server (NTRS)

Sunderland, Peter B.; Greenbberg, Paul S.; Urban, David L.; Wernet, Mark P.; Yanis, William

2001-01-01

Despite numerous experimental investigations, the characterization of microgravity laminar jet diffusion flames remains incomplete. Measurements to date have included shapes, temperatures, soot properties, radiative emissions and compositions, but full-field quantitative measurements of velocity are lacking. Since the differences between normal-gravity and microgravity diffusion flames are fundamentally influenced by changes in velocities, it is imperative that the associated velocity fields be measured in microgravity flames. Velocity measurements in nonbuoyant flames will be helpful both in validating numerical models and in interpreting past microgravity combustion experiments. Pointwise velocity techniques are inadequate for full-field velocity measurements in microgravity facilities. In contrast, Particle Image Velocimetry (PIV) can capture the entire flow field in less than 1% of the time required with Laser Doppler Velocimetry (LDV). Although PIV is a mature diagnostic for normal-gravity flames , restrictions on size, power and data storage complicate these measurements in microgravity. Results from the application of PIV to gas jet flames in normal gravity are presented here. Ethane flames burning at 13, 25 and 50 kPa are considered. These results are presented in more detail in Wernet et al. (2000). The PIV system developed for these measurements recently has been adapted for on-rig use in the NASA Glenn 2.2-second drop tower.

HOW AGN JETS HEAT THE INTRACLUSTER MEDIUM—INSIGHTS FROM HYDRODYNAMIC SIMULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karen Yang, H.-Y.; Reynolds, Christopher S., E-mail: hsyang@astro.umd.edu

Feedback from active galactic nuclei (AGNs) is believed to prevent catastrophic cooling in galaxy clusters. However, how the feedback energy is transformed into heat, and how the AGN jets heat the intracluster medium (ICM) isotropically, still remain elusive. In this work, we gain insights into the relative importance of different heating mechanisms using three-dimensional hydrodynamic simulations including cold gas accretion and momentum-driven jet feedback, which are the most successful models to date in terms of reproducing the properties of cool cores. We find that there is net heating within two “jet cones” (within ∼30° from the axis of jet precession)more » where the ICM gains entropy by shock heating and mixing with the hot thermal gas within bubbles. Outside the jet cones, the ambient gas is heated by weak shocks, but not enough to overcome radiative cooling, therefore, forming a “reduced” cooling flow. Consequently, the cluster core is in a process of “gentle circulation” over billions of years. Within the jet cones, there is significant adiabatic cooling as the gas is uplifted by buoyantly rising bubbles; outside the cones, energy is supplied by the inflow of already-heated gas from the jet cones as well as adiabatic compression as the gas moves toward the center. In other words, the fluid dynamics self-adjusts such that it compensates and transports the heat provided by the AGN, and hence no fine-tuning of the heating profile of any process is necessary. Throughout the cluster evolution, turbulent energy is only at the percent level compared to gas thermal energy, and thus turbulent heating is not the main source of heating in our simulation.« less

Loop system for creating jet fuel vapor standards used in the calibration of infrared spectrophotometers and gas chromatographs.

PubMed

Reboulet, James; Cunningham, Robert; Gunasekar, Palur G; Chapman, Gail D; Stevens, Sean C

2009-02-01

A whole body inhalation study of mixed jet fuel vapor and its aerosol necessitated the development of a method for preparing vapor only standards from the neat fuel. Jet fuel is a complex mixture of components which partitions between aerosol and vapor when aspirated based on relative volatility of the individual compounds. A method was desired which could separate the vapor portion from the aerosol component to prepare standards for the calibration of infrared spectrophotometers and a head space gas chromatography system. A re-circulating loop system was developed which provided vapor only standards whose composition matched those seen in an exposure system. Comparisons of nominal concentrations in the exposure system to those determined by infrared spectrophotometry were in 92-95% agreement. Comparison of jet fuel vapor concentrations determined by infrared spectrophotometry compared to head space gas chromatography yielded a 93% overall agreement in trial runs. These levels of agreement show the loop system to be a viable method for creating jet fuel vapor standards for calibrating instruments.

Bipolar outflows and Jets From Young Stars

NASA Astrophysics Data System (ADS)

Bally, J.

2000-05-01

Stars produce powerful jets and winds during their birth. These primary outflows power shock waves (Herbig-Haro objects) and entrain surrounding gas to produce molecular outflows. Many outflows reach parsec-scale dimensions whose dynamical ages can become comparable to the accretion age of the source star. Thus, these giant outflows provide fossil records of the mass loss histories of their parent stars. Jet symmetries provide tantalizing clues about the violent history of stellar accretion and dynamical interactions with nearby companions. These flows inject sufficient energy and momentum into the surrounding medium to alter the physical and chemical state of the gas, generate turbulence, disrupt the parent cloud, and self-regulate the rate of star formation. Recent observations have revealed a new class of externally irradiated jets which are rendered visible by the light of nearby massive stars. Some of these jets appear to be millions of years old, indicating that outflow activity can persist for much longer than previously thought. Stellar jets provide ideal laboratories for the investigation of accretion powered outflows and associated shocks since their time-dependent behavior can be observed with a rich variety of spectral line diagnostics.

Comet Wild 2 - Jet Release

NASA Technical Reports Server (NTRS)

2004-01-01

This composite image was taken by the navigation camera during the close approach phase of Stardust's Jan 2, 2004 flyby of comet Wild 2. Several large depressed regions can be seen. Comet Wild 2 is about five kilometers (3.1 miles) in diameter. To create this image, a short exposure image showing tremendous surface detail was overlain on a long exposure image taken just 10 seconds later showing jets. Together, the images show an intensely active surface, jetting dust and gas streams into space and leaving a trail millions of kilometers long.

Levels in N 12 via the N 14 ( p ,   t ) reaction using the JENSA gas-jet target

DOE PAGES

Chipps, K. A.; Pain, S. D.; Greife, U.; ...

2015-09-25

As one of a series of physics cases to demonstrate the unique benefit of the new Jet Experiments in Nuclear Structure and Astrophysics gas-jet target for enabling next-generation transfer reaction studies, the ¹⁴N (p, t)¹²N reaction was studied for the first time, using a pure jet of nitrogen, in an attempt to resolve conflicting information on the structure of ¹²N. A new level at 4.561-MeV excitation energy in ¹²N was found.

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

NASA Astrophysics Data System (ADS)

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

2012-08-01

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

Estimation of Flow Channel Parameters for Flowing Gas Mixed with Air in Atmospheric-pressure Plasma Jets

NASA Astrophysics Data System (ADS)

Yambe, Kiyoyuki; Saito, Hidetoshi

2017-12-01

When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma flows into free space, the diameter of the resulting flow channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the flow channel. When the working gas flows into the atmosphere from the inside of a quartz tube, the gas mixes with air. The molar ratio of the working gas and air is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas flow rates for the upper limit of laminar flow and the lower limit of turbulent flow are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas flow rate until the rate for the upper limit of laminar flow and the lower limit of turbulent flow, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the flow channel and the molar ratio by using the cylindrical approximation.

Mixing characterization of highly underexpanded fluid jets with real gas expansion

NASA Astrophysics Data System (ADS)

Förster, Felix J.; Baab, Steffen; Steinhausen, Christoph; Lamanna, Grazia; Ewart, Paul; Weigand, Bernhard

2018-03-01

We report a comprehensive speed of sound database for multi-component mixing of underexpanded fuel jets with real gas expansion. The paper presents several reference test cases with well-defined experimental conditions providing quantitative data for validation of computational simulations. Two injectant fluids, fundamentally different with respect to their critical properties, are brought to supercritical state and discharged into cold nitrogen at different pressures. The database features a wide range of nozzle pressure ratios covering the regimes that are generally classified as highly and extremely highly underexpanded jets. Further variation is introduced by investigating different injection temperatures. Measurements are obtained along the centerline at different axial positions. In addition, an adiabatic mixing model based on non-ideal thermodynamic mixture properties is used to extract mixture compositions from the experimental speed of sound data. The concentration data obtained are complemented by existing experimental data and represented by an empirical fit.

Comparison between the water activation effects by pulsed and sinusoidal helium plasma jets

NASA Astrophysics Data System (ADS)

Xu, Han; Liu, Dingxin; Xia, Wenjie; Chen, Chen; Wang, Weitao; Liu, Zhijie; Wang, Xiaohua; Kong, Michael G.

2018-01-01

Comparisons between pulsed and sinusoidal plasma jets have been extensively reported for the discharge characteristics and gaseous reactive species, but rarely for the aqueous reactive species in water solutions treated by the two types of plasma jets. This motivates us to compare the concentrations of aqueous reactive species induced by a pulsed and a sinusoidal plasma jet, since it is widely reported that these aqueous reactive species play a crucial role in various plasma biomedical applications. Experimental results show that the aqueous H2O2, OH/O2-, and O2-/ONOO- induced by the pulsed plasma jet have higher concentrations, and the proportional difference increases with the discharge power. However, the emission intensities of OH(A) and O(3p5P) are higher for the sinusoidal plasma jet, which may be attributed to its higher gas temperature since more water vapor could participate in the plasma. In addition, the efficiency of bacterial inactivation induced by the pulsed plasma jet is higher than that for the sinusoidal plasma jet, in accordance with the concentration relation of aqueous reactive species for the two types of plasma jets.

Modeling the field of a passive scalar in a nonisothermal turbulent plane gas jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrashin, V.N.; Barykin, V.N.; Martynenko, O.G.

The problem of the distribution of thermal characteristics in a plane nonisothermal turbulent gas jet in the case of large Reynolds numbers and a small temperature difference, allowing heat to be regarded as a passive impurity, is solved in the range of jet cross sections 20-100 caliber by a second-order correlational model of turbulence and an effective numerical algorithm. Analysis of the results show that the model allows computational data in good agreement with experiment to be obtained in the range of jet cross section 20-100 diameters. The relative error in determining the maximum values of the functions is 3-10%more » for the dynamic characteristics while the mean temperature and its mean square pulsations are determined with an accuracy of 5-10%; the corresponding figures for the thermal characteristics are 5-15% and 5-10%.« less

Diagnostics of an AC driven atmospheric pressure non-thermal plasma jet and its use for radially directed jet array

NASA Astrophysics Data System (ADS)

Zhu, W.; Wang, R.

2017-08-01

An alternating current atmospheric pressure plasma jet is generated with noble gas or noble gas/oxygen admixture as working gas. A "core plasma filament" is observed at the center of the dielectric tube and extends to the plasma jet at higher peak-to-peak voltages. This type of plasma jet is believed to be of the same nature with the reported plasma bullet driven by pulsed DC power sources. Double current probes are used to assess the speed of the plasma bullet and show that the speed is around 104-105 m/s. The time dependence of the downstream bullet speed is attributed to the gas heating and in turn the increase of the reduced electric field E/N. Optical emission spectra show the dependence of helium and oxygen emission intensities on the concentration of oxygen additive in the carrier gas, with peak values found at 0.5% O2. Multiple radial jets are realized on dielectric tubes of different sizes. As a case study, one of these multi-jet devices is used to treat B. aureus on the inner surface of a plastic beaker and is shown to be more effective than a single jet.

Active control of continuous air jet with bifurcated synthetic jets

NASA Astrophysics Data System (ADS)

Dančová, Petra; Vít, Tomáš; Jašíková, Darina; Novosád, Jan

The synthetic jets (SJs) have many significant applications and the number of applications is increasing all the time. In this research the main focus is on the primary flow control which can be used effectively for the heat transfer increasing. This paper deals with the experimental research of the effect of two SJs worked in the bifurcated mode used for control of an axisymmetric air jet. First, the control synthetic jets were measured alone. After an adjustment, the primary axisymmetric jet was added in to the system. For comparison, the primary flow without synthetic jets control was also measured. All experiments were performed using PIV method whereby the synchronization between synthetic jets and PIV system was necessary to do.

Gas Cloud Accretion onto the SMBH SgrA* and Formation of Jet 4

NASA Astrophysics Data System (ADS)

Nishiyama, Shogo

2015-06-01

A dense gas cloud was detected to be rapidly approaching the Galactic supermassive black hole (SMBH) Sgr A*, and was 1,600 Schwarzschild radii from the SMBH at the pericenter of its eccentric orbit in Mar 2014. Ongoing tidal disruption has been observed, and cloud fragments are expected to accrete onto the SMBH on dynamical timescales, suggesting a jet formation in the following years. So we are carrying out daily monitoring observations of Sgr A* in near-infrared and radio wavelengths, and we propose quick follow-up observations with Subaru/Gemini. Br-gamma line emission maps obtained with Gemini/NIFS will be used to fine tune our 3D simulation to estimate how much mass accretes, and when the fragments accrete onto the SMBH. Polarimetric and astrometric signals from a jet taken with Subaru/HiCIAO and KaVA will be compared with the finely tuned simulation to understand the timescale of jet formation, and to investigate the correlation between the accreted mass of the cloud fragments and a luminosity of the newly-formed jet. Spectroscopic and imaging observations from 1.6 - 11 mum (Subaru/IRCS, COMICS) will also be conducted to understand processes responsible for near to mid-infrared emission during the accretion event.

A Connection Between Corona and Jet

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-03-01

The structure immediately around a supermassive black hole at the heart of an active galaxy can tell us about how material flows in and out of these monsters but this region is hard to observe! A new study provides us with clues of what might be going on in these active and energetic cores of galaxies.In- and OutflowsIn active galactic nuclei (AGN), matter flows both in and out. As material flows toward the black hole via its surrounding accretion disk, much of this gas and dust can then be expelled from the vicinity via highly collimated jets.Top: The fraction of X-rays that is reflected decreases as jet power increases. Bottom: the distance between the corona and the reflecting part of the disk increases as jet power increases. [Adapted from King et al. 2017]To better understand this symbiosis between accretion and outflows, we examine whats known as the corona the hot, X-ray-emitting gas thats located in the closest regions around the black hole. But because the active centers of galaxies are generally obscured by surrounding gas and dust, its difficult for us to learn about the structure of these inner regions near the black hole.Where are the X-rays of the corona produced: in the inner accretion flow, or at the base of the jet? How far away is this corona from the disk? And how does the coronas behavior relate to that of the jet?Reflected ObservationsTo address some of these questions, a group of scientists led by Ashley King (Einstein Fellow at Stanford University) has analyzed X-ray observations from NuSTAR and XMM-Newton of over 40 AGN. The team examined the reflections of the X-rays off of the accretion disk and used two measurements to learn about the structure around the black hole:the fraction of the coronas X-rays that are reflected by the disk, andthe time lag between the original and reflected X-rays, which reveals the distance from the corona to the reflecting part of the disk.A visualization of the authors model for an AGN. The accretion disk is

Comet Wild 2 - Jet Release

NASA Image and Video Library

2004-03-18

This composite image was taken by the navigation camera during the close approach phase of Stardust's Jan 2, 2004 flyby of comet Wild 2. Several large depressed regions can be seen. Comet Wild 2 is about five kilometers (3.1 miles) in diameter. To create this image, a short exposure image showing tremendous surface detail was overlain on a long exposure image taken just 10 seconds later showing jets. Together, the images show an intensely active surface, jetting dust and gas streams into space and leaving a trail millions of kilometers long. http://photojournal.jpl.nasa.gov/catalog/PIA05578

Active control of jet flowfields

NASA Astrophysics Data System (ADS)

Kibens, Valdis; Wlezien, Richard W.

1987-06-01

Passive and active control of jet shear layer development were investigated as mechanisms for modifying the global characteristics of jet flowfields. Slanted and stepped indeterminate origin (I.O.) nozzles were used as passive, geometry-based control devices which modified the flow origins. Active control techniques were also investigated, in which periodic acoustic excitation signals were injected into the I.O. nozzle shear layers. Flow visualization techniques based on a pulsed copper-vapor laser were used in a phase-conditioned image acquisition mode to assemble optically averaged sets of images acquired at known times throughout the repetition cycle of the basic flow oscillation period. Hot wire data were used to verify the effect of the control techniques on the mean and fluctuating flow properties. The flow visualization images were digitally enhanced and processed to show locations of prominent vorticity concentrations. Three-dimensional vortex interaction patterns were assembled in a format suitable for movie mode on a graphic display workstation, showing the evolution of three-dimensional vortex system in time.

Production of simplex RNS and ROS by nanosecond pulse N2/O2 plasma jets with homogeneous shielding gas for inducing myeloma cell apoptosis

NASA Astrophysics Data System (ADS)

Liu, Zhijie; Xu, Dehui; Liu, Dingxin; Cui, Qingjie; Cai, Haifeng; Li, Qiaosong; Chen, Hailan; Kong, Michael G.

2017-05-01

In this paper, atmospheric pressure N2/O2 plasma jets with homogeneous shielding gas excited by nanosecond pulse are obtained to generate simplex reactive nitrogen species (RNS) and reactive oxygen species (ROS), respectively, for the purpose of studying the simplex RNS and ROS to induce the myeloma cell apoptosis with the same discharge power. The results reveal that the cell death rate by the N2 plasma jet with N2 shielding gas is about two times that of the O2 plasma jet with O2 shielding gas for the equivalent treatment time. By diagnosing the reactive species of ONOO-, H2O2, OH and \\text{O}2- in medium, our findings suggest the cell death rate after plasma jets treatment has a positive correlation with the concentration of ONOO-. Therefore, the ONOO- in medium is thought to play an important role in the process of inducing myeloma cell apoptosis.

Do Radio Jets Contribute to Driving Ionized Gas Outflows in Moderate Luminosity Type 2 AGN?

NASA Astrophysics Data System (ADS)

Fowler, Julia; Sajina, Anna; Lacy, Mark

2016-01-01

This poster examines the role of AGN-driven feedback in low to intermediate power radio galaxies. We begin with [OIII] measurements of ionized gas outflows in 29 moderate AGN-luminosity z~0.3-0.7 dust-obscured Type 2 AGN. We aim to examine the relative role of the AGN itself, of star-formation and of nascent radio jets in driving these outflows. The strength of the AGN and star formation are based on the [OIII] luminosities, and the far-IR luminosities respectively. For the radio jets, we present multi-frequency radio (X, S, and L-bands) JVLA imaging of our sample, which allows us both to constrain the overall radio power, but also look for signatures of young radio sources, including Giga-hertz Peaked Spectrum (GPS) sources, as well as small-scale jets. While radio jet-driven outflows are well known for powerful radio-loud galaxies, this study allows us to constrain the degree to which this mechanism is significant at more modest radio luminosities of L5GHz~10^22-25 W/Hz.

Activities of the Jet Propulsion Laboratory

NASA Technical Reports Server (NTRS)

1986-01-01

Work accomplished by the Jet Propulsion Laboratory (JPL) under contract to NASA in 1985 is described. The work took place in the areas of flight projects, space science, geodynamics, materials science, advanced technology, defense and civil programs, telecommunications systems, and institutional activities.

MINIFILAMENT ERUPTIONS THAT DRIVE CORONAL JETS IN A SOLAR ACTIVE REGION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.

We present observations of eruptive events in an active region adjacent to an on-disk coronal hole on 2012 June 30, primarily using data from the Solar Dynamics Observatory ( SDO )/Atmospheric Imaging Assembly (AIA), SDO /Helioseismic and Magnetic Imager (HMI), and STEREO - B . One eruption is of a large-scale (∼100″) filament that is typical of other eruptions, showing slow-rise onset followed by a faster-rise motion starting as flare emissions begin. It also shows an “EUV crinkle” emission pattern, resulting from magnetic reconnections between the exploding filament-carrying field and surrounding field. Many EUV jets, some of which are surges,more » sprays and/or X-ray jets, also occur in localized areas of the active region. We examine in detail two relatively energetic ones, accompanied by GOES M1 and C1 flares, and a weaker one without a GOES signature. All three jets resulted from small-scale (∼20″) filament eruptions consistent with a slow rise followed by a fast rise occurring with flare-like jet-bright-point brightenings. The two more-energetic jets showed crinkle patters, but the third jet did not, perhaps due to its weakness. Thus all three jets were consistent with formation via erupting minifilaments, analogous to large-scale filament eruptions and to X-ray jets in polar coronal holes. Several other energetic jets occurred in a nearby portion of the active region; while their behavior was also consistent with their source being minifilament eruptions, we could not confirm this because their onsets were hidden from our view. Magnetic flux cancelation and emergence are candidates for having triggered the minifilament eruptions.« less

On the start up of supersonic underexpanded jets

NASA Astrophysics Data System (ADS)

Lacerda, Nehemias Lima

An impulsively started jet can be formed by a gas confined in a high pressure reservoir that escapes suddenly through an exit orifice, into a controlled atmosphere. Supersonic gas jets of this type are unsteady and differ from the steady jet that develops later by the presence of a bow shock, a jet head and a nonstationary Mach disk. The effects of the pressure ratio between the high pressure gas inside the reservoir and the lower pressure atmospheric gas, as well as the gas combination used, are studied experimentally. The gases used for the jet and the atmosphere were selected from helium, nitrogen and sulfur hexafluoride. The data acquisition consisted of: high resolution flash photography to obtain detail from the pictures; high-speed movie pictures to obtain the time development of selected features; and fast-response pressure transducers located at the reservoir end plate, the tank end plate and the jet exit. The initial development of the jet is highly time dependent. During this phase, the shape that the jet assumes varies with pressure ratio and with the choice of gas. In particular an extremely light gas exhausting into a heavy atmosphere, exhibits an uncommon shape. It develops as a bubble wrapped by the bow shock, that increases its volume with flow time and pressure ratio. As the pressure ratio increases, it becomes more tightly wrapped by the bow shock. At later times the jet assumes conventional linear growth. After the jet starts, a Mach disk is observed close to the jet exit which moves downstream as the exit pressure builds up. The monotonic increase in exit pressure is caused by the slow breaking of the diaphragm. The position of the Mach disk is furthest from the jet exit when the exit pressure is a maximum. After that it oscillates around the location predicted by the steady theory of Ashkenas and Sherman (1966) at a frequency close to one of the resonant frequencies of the reservoir. The features observed for the inner structure of the jet

A Radio Jet Drives a Molecular and Atomic Gas Outflow in Multiple Regions within One Square Kiloparsec of the Nucleus of the nearby Galaxy IC5063

NASA Astrophysics Data System (ADS)

Dasyra, K. M.; Bostrom, A. C.; Combes, F.; Vlahakis, N.

2015-12-01

We analyzed near-infrared data of the nearby galaxy IC5063 taken with the Very Large Telescope SINFONI instrument. IC5063 is an elliptical galaxy that has a radio jet nearly aligned with the major axis of a gas disk in its center. The data reveal multiple signatures of molecular and atomic gas that has been kinematically distorted by the passage of the jet plasma or cocoon within an area of ˜1 kpc2. Concrete evidence that the interaction of the jet with the gas causes the gas to accelerate comes from the detection of outflows in four different regions along the jet trail: near the two radio lobes, between the radio emission tip and the optical narrow-line-region cone, and at a region with diffuse 17.8 GHz emission midway between the nucleus and the north radio lobe. The outflow in the latter region is biconical, centered 240 pc away from the nucleus, and oriented perpendicularly to the jet trail. The diffuse emission that is observed as a result of the gas entrainment or scattering unfolds around the trail and away from the nucleus with increasing velocity. It overall extends for ≳700 pc parallel and perpendicular to the trail. Near the outflow starting points, the gas has a velocity excess of 600-1200 km s-1 with respect to ordered motions, as seen in [Fe ii], {Pa}α , or {{{H}}}2 lines. High {{{H}}}2 (1-0) S(3)/S(1) flux ratios indicate non-thermal excitation of gas in the diffuse outflow.

Multiple jet study data correlations. [data correlation for jet mixing flow of air jets

NASA Technical Reports Server (NTRS)

Walker, R. E.; Eberhardt, R. G.

1975-01-01

Correlations are presented which allow determination of penetration and mixing of multiple cold air jets injected normal to a ducted subsonic heated primary air stream. Correlations were obtained over jet-to-primary stream momentum flux ratios of 6 to 60 for locations from 1 to 30 jet diameters downstream of the injection plane. The range of geometric and operating variables makes the correlations relevant to gas turbine combustors. Correlations were obtained for the mixing efficiency between jets and primary stream using an energy exchange parameter. Also jet centerplane velocity and temperature trajectories were correlated and centerplane dimensionless temperature distributions defined. An assumption of a Gaussian vertical temperature distribution at all stations is shown to result in a reasonable temperature field model. Data are presented which allow comparison of predicted and measured values over the range of conditions specified above.

Searching for order in atmospheric pressure plasma jets

NASA Astrophysics Data System (ADS)

Schäfer, Jan; Sigeneger, Florian; Šperka, Jiří; Rodenburg, Cornelia; Foest, Rüdiger

2018-01-01

The self-organized discharge behaviour occurring in a non-thermal radio-frequency plasma jet in rare gases at atmospheric pressure was investigated. The frequency of the azimuthal rotation of filaments in the active plasma volume and their inclination were measured along with the gas temperature under varying discharge conditions. The gas flow and heating were described theoretically by a three-dimensional hydrodynamic model. The rotation frequencies obtained by both methods qualitatively agree. The results demonstrate that the plasma filaments forming an inclination angle α with the axial gas velocity u z are forced to a transversal movement with the velocity {u}φ =\\tan (α )\\cdot {u}z, which is oriented in the inclination direction. Variations of {u}φ in the model reveal that the observed dynamics minimizes the energy loss due to convective heat transfer by the gas flow. The control of the self-organization regime motivates the application of the plasma jet for precise and reproducible material processing.

Numerical simulation of the gas-liquid interaction of a liquid jet in supersonic crossflow

NASA Astrophysics Data System (ADS)

Li, Peibo; Wang, Zhenguo; Sun, Mingbo; Wang, Hongbo

2017-05-01

The gas-liquid interaction process of a liquid jet in supersonic crossflow with a Mach number of 1.94 was investigated numerically using the Eulerian-Lagrangian method. The KH (Kelvin-Helmholtz) breakup model was used to calculate the droplet stripping process, and the secondary breakup process was simulated by the competition of RT (Rayleigh-Taylor) breakup model and TAB (Taylor Analogy Breakup) model. A correction of drag coefficient was proposed by considering the compressible effects and the deformation of droplets. The location and velocity models of child droplets after breakup were improved according to droplet deformation. It was found that the calculated spray features, including spray penetration, droplet size distribution and droplet velocity profile agree reasonably well with the experiment. Numerical results revealed that the streamlines of air flow could intersect with the trajectory of droplets and are deflected towards the near-wall region after they enter into spray zone around the central plane. The analysis of gas-liquid relative velocity and droplet deformation suggested that the breakup of droplets mainly occurs around the front region of the spray where gathered a large number of droplets with different sizes. The liquid trailing phenomenon of jet spray which has been discovered by the previous experiment was successfully captured, and a reasonable explanation was given based on the analysis of gas-liquid interaction process.

Relativistic jets in SS 433

NASA Astrophysics Data System (ADS)

Margon, B.

1982-01-01

A variety of recent optical, radio, and X-ray observations have confirmed the hypothesis that the peculiar star SS 433 is ejecting two narrow, opposed, highly collimated jets of matter at one-quarter the speed of light. This unique behavior is probably driven by mass exchange between a relatively normal star and a compact companion, either a neutron star or a black hole. However, numerous details regarding the energetics, radiation, acceleration, and collimation of the jets remain to be understood. This phenomenon may well be a miniature example of similar collimated ejection of gas by active extragalactic objects such as quasars and radio galaxies.

Photoballistics of volcanic jet activity at Stromboli, Italy

NASA Technical Reports Server (NTRS)

Chouet, B.; Hamisevicz, N.; Mcgetchin, T. R.

1974-01-01

Two night eruptions of the volcano Stromboli were studied through 70-mm photography. Single-camera techniques were used. Particle sphericity, constant velocity in the frame, and radial symmetry were assumed. Properties of the particulate phase found through analysis include: particle size, velocity, total number of particles ejected, angular dispersion and distribution in the jet, time variation of particle size and apparent velocity distribution, averaged volume flux, and kinetic energy carried by the condensed phase. The frequency distributions of particle size and apparent velocities are found to be approximately log normal. The properties of the gas phase were inferred from the fact that it was the transporting medium for the condensed phase. Gas velocity and time variation, volume flux of gas, dynamic pressure, mass erupted, and density were estimated. A CO2-H2O mixture is possible for the observed eruptions. The flow was subsonic. Velocity variations may be explained by an organ pipe resonance. Particle collimation may be produced by a Magnus effect.

Life-cycle analysis of greenhouse gas emissions from renewable jet fuel production.

PubMed

de Jong, Sierk; Antonissen, Kay; Hoefnagels, Ric; Lonza, Laura; Wang, Michael; Faaij, André; Junginger, Martin

2017-01-01

The introduction of renewable jet fuel (RJF) is considered an important emission mitigation measure for the aviation industry. This study compares the well-to-wake (WtWa) greenhouse gas (GHG) emission performance of multiple RJF conversion pathways and explores the impact of different co-product allocation methods. The insights obtained in this study are of particular importance if RJF is included as an emission mitigation instrument in the global Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA). Fischer-Tropsch pathways yield the highest GHG emission reduction compared to fossil jet fuel (86-104%) of the pathways in scope, followed by Hydrothermal Liquefaction (77-80%) and sugarcane- (71-75%) and corn stover-based Alcohol-to-Jet (60-75%). Feedstock cultivation, hydrogen and conversion inputs were shown to be major contributors to the overall WtWa GHG emission performance. The choice of allocation method mainly affects pathways yielding high shares of co-products or producing co-products which effectively displace carbon intensive products (e.g., electricity). Renewable jet fuel can contribute to significant reduction of aviation-related GHG emissions, provided the right feedstock and conversion technology are used. The GHG emission performance of RJF may be further improved by using sustainable hydrogen sources or applying carbon capture and storage. Based on the character and impact of different co-product allocation methods, we recommend using energy and economic allocation (for non-energy co-products) at a global level, as it leverages the universal character of energy allocation while adequately valuing non-energy co-products.

The jet-disk symbiosis without maximal jets: 1D hydrodynamical jets revisited

NASA Astrophysics Data System (ADS)

Crumley, Patrick; Ceccobello, Chiara; Connors, Riley M. T.; Cavecchi, Yuri

2017-05-01

In this work we discuss the recent criticism by Zdziarski (2016, A&A, 586, A18) of the maximal jet model derived in Falcke & Biermann (1995, A&A, 293, 665). We agree with Zdziarski that in general a jet's internal energy is not bounded by its rest-mass energy density. We describe the effects of the mistake on conclusions that have been made using the maximal jet model and show when a maximal jet is an appropriate assumption. The maximal jet model was used to derive a 1D hydrodynamical model of jets in agnjet, a model that does multiwavelength fitting of quiescent/hard state X-ray binaries and low-luminosity active galactic nuclei. We correct algebraic mistakes made in the derivation of the 1D Euler equation and relax the maximal jet assumption. We show that the corrections cause minor differences as long as the jet has a small opening angle and a small terminal Lorentz factor. We find that the major conclusion from the maximal jet model, the jet-disk symbiosis, can be generally applied to astrophysical jets. We also show that isothermal jets are required to match the flat radio spectra seen in low-luminosity X-ray binaries and active galactic nuclei, in agreement with other works.

Investigation of the trajectories and length of combustible gas jet flames in a sweeping air stream

NASA Astrophysics Data System (ADS)

Polezhaev, Yu. V.; Mostinskii, I. L.; Lamden, D. I.; Stonik, O. G.

2011-05-01

The trajectories of round gas jets and jet flames introduced into a sweeping air stream are studied. The influence of various initial conditions and of the physical properties of gases on the trajectory is considered. Experimental verification of the available approximation relations for the trajectories of flames in a wide range of the values of the blowing ratio has been carried out. It is shown that the newly obtained experimental approximation of the trajectory shape differs from the existing ones by about 20%. At small values of the blowing ratio (smaller than ~4.5) the flame trajectories cease to depend on it.

Technical and Scientific Aspects of the JET Trace-Tritium Experimental Campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, T.T.C.; Brennan, D; Pearce, R.J.H.

The JET Trace Tritium (TTE) programme marked the first use of tritium in experiments under the managerial control of UKAEA, which operates the JET Facility on behalf of EFDA. The introduction of tritium into the plasma by gas fuelling and neutral beam injection, even in trace quantities, required the mobilisation of gram-quantities of tritium gas from the Active Gas Handling System (AGHS) product storage units into the supply lines connected to the torus gas valve and the neutral beam injectors. All systems for DT gas handling, recovery and reprocessing were therefore recommissioned and operating procedures re-established, involving extensive operations staffmore » training. The validation of Key Safety Related Equipment (KSRE) is described with reference to specific examples. The differences between requirements for TTE and full DT operations are shown to be relatively small. The scientific motivation for TTE, such as the possibility to obtain high-quality measurements in key areas such as fuel-ion transport and fast ion dynamics, is described, and the re-establishment and development of JET's 14MeV neutron diagnostic capability for TTE and future DT campaigns are outlined. Some scientific highlights from the TTE campaign are presented.« less

On the Jet Properties of γ-Ray-loud Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Chen, Liang

2018-04-01

Based on broadband spectral energy distributions (SEDs), we estimate the jet physical parameters of 1392 γ-ray-loud active galactic nuclei (AGNs), the largest sample so far. The (SED) jet power and magnetization parameter are derived for these AGNs. Out of these sources, the accretion disk luminosity of 232 sources and (extended) kinetic jet powers of 159 sources are compiled from archived papers. We find the following. (1) Flat-spectrum radio quasars (FSRQs) and BL Lacs are well separated by {{Γ }}=-0.127{log}{L}γ +8.18 in the γ-ray luminosity versus photon index plane with a success rate of 88.6%. (2) Most FSRQs present a (SED) jet power larger than the accretion power, which suggests that the relativistic jet-launching mechanism is dominated by the Blandford–Znajek process. This result confirms previous findings. (3) There is a significant anticorrelation between jet magnetization and a ratio of the (SED) jet power to the (extended) kinetic jet power, which, for the first time, provides supporting evidence for the jet energy transportation theory: a high-magnetization jet may more easily transport energy to a large scale than a low-magnetization jet.

Sheet production apparatus for removing a crystalline sheet from the surface of a melt using gas jets located above and below the crystalline sheet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kellerman, Peter L.; Thronson, Gregory D.

In one embodiment, a sheet production apparatus comprises a vessel configured to hold a melt of a material. A cooling plate is disposed proximate the melt and is configured to form a sheet of the material on the melt. A first gas jet is configured to direct a gas toward an edge of the vessel. A sheet of a material is translated horizontally on a surface of the melt and the sheet is removed from the melt. The first gas jet may be directed at the meniscus and may stabilize this meniscus or increase local pressure within the meniscus.

Impact of red giant/AGB winds on active galactic nucleus jet propagation

NASA Astrophysics Data System (ADS)

Perucho, M.; Bosch-Ramon, V.; Barkov, M. V.

2017-10-01

Context. Dense stellar winds may mass-load the jets of active galactic nuclei, although it is unclear on what time and spatial scales the mixing takes place. Aims: Our aim is to study the first steps of the interaction between jets and stellar winds, and also the scales on which the stellar wind mixes with the jet and mass-loads it. Methods: We present a detailed 2D simulation - including thermal cooling - of a bubble formed by the wind of a star designed to study the initial stages of jet-star interaction. We also study the first interaction of the wind bubble with the jet using a 3D simulation in which the star enters the jet. Stability analysis is carried out for the shocked wind structure to evaluate the distances over which the jet-dragged wind, which forms a tail, can propagate without mixing with the jet flow. Results.The 2D simulations point to quick wind bubble expansion and fragmentation after about one bubble shock crossing time. Three-dimensional simulations and stability analysis point to local mixing in the case of strong perturbations and relatively low density ratios between the jet and the jet dragged-wind, and to a possibly more stable shocked wind structure at the phase of maximum tail mass flux. Analytical estimates also indicate that very early stages of the star jet-penetration time may be also relevant for mass-loading. The combination of these and previous results from the literature suggests highly unstable interaction structures and efficient wind-jet flow mixing on the scale of the jet interaction height. Conclusions: The winds of stars with strong mass loss can efficiently mix with jets from active galactic nuclei. In addition, the initial wind bubble shocked by the jet leads to a transient, large interaction surface. The interaction between jets and stars can produce strong inhomogeneities within the jet. As mixing is expected to be effective on large scales, even individual asymptotic giant branch stars can significantly contribute to

Domain-adaptive finite difference methods for collapsing annular liquid jets

NASA Astrophysics Data System (ADS)

Ramos, J. I.

1993-01-01

A domain-adaptive technique which maps a time-dependent, curvilinear geometry into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets. A method of lines is used to solve the one-dimensional fluid dynamics equations written in weak conservation-law form, and upwind differences are employed to evaluate the axial convective fluxes. The unknown, time-dependent, axial location of the downstream boundary is determined from the solution of an ordinary differential equation which is nonlinearly coupled to the fluid dynamics and gas concentration equations. The equation for the gas concentration in the annular liquid jet is written in strong conservation-law form and solved by means of a method of lines at high Peclet numbers and a line Gauss-Seidel method at low Peclet numbers. The effects of the number of grid points along and across the annular jet, time step, and discretization of the radial convective fluxes on both the steady state mass absorption rate and the jet's collapse rate have been analyzed on staggered and non-staggered grids. The steady state mass absorption rate and the collapse of annular liquid jets are determined as a function of the Froude, Peclet and Weber numbers, annular jet's thickness-to-radius ratio at the nozzle exit, initial pressure difference across the annular jet, nozzle exit angle, temperature of the gas enclosed by the annular jet, pressure of the gas surrounding the jet, solubilities at the inner and outer interfaces of the annular jet, and gas concentration at the nozzle exit. It is shown that the steady state mass absorption rate is proportional to the inverse square root of the Peclet number except for low values of this parameter, and that the possible mathematical incompatibilities in the concentration field at the nozzle exit exert a great influence on the steady state mass absorption rate and on the jet collapse. It is also shown that the steady state mass absorption

Steady-state and dynamic analysis of a jet engine, gas lubricated shaft seal

NASA Technical Reports Server (NTRS)

Shapiro, W.; Colsher, R.

1974-01-01

Dynamic response of a gas-lubricated, jet-engine main shaft seal was analytically established as a function of collar misalignment and secondary seal friction. Response was obtained by a forward integration-in-time (time-transient) scheme, which traces a time history of seal motions in all its degrees of freedom. Results were summarized in the form of a seal tracking map which indicated regions of acceptable collar misalignments and secondary seal friction. Methodology, results and interpretations are comprehensively described.

Turbine exhaust diffuser with a gas jet producing a coanda effect flow control

DOEpatents

Orosa, John; Montgomery, Matthew

2014-02-11

An exhaust diffuser system and method for a turbine engine includes an inner boundary and an outer boundary with a flow path defined therebetween. The inner boundary is defined at least in part by a hub structure that has an upstream end and a downstream end. The outer boundary may include a region in which the outer boundary extends radially inward toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. The hub structure includes at least one jet exit located on the hub structure adjacent to the upstream end of the tail cone. The jet exit discharges a flow of gas substantially tangential to an outer surface of the tail cone to produce a Coanda effect and direct a portion of the exhaust flow in the diffuser toward the inner boundary.

Simulations of AGN jets: magnetic kink instability versus conical shocks

NASA Astrophysics Data System (ADS)

Barniol Duran, Rodolfo; Tchekhovskoy, Alexander; Giannios, Dimitrios

2017-08-01

Relativistic jets in active galactic nuclei (AGN) convert as much as half of their energy into radiation. To explore the poorly understood processes that are responsible for this conversion, we carry out fully 3D magnetohydrodynamic (MHD) simulations of relativistic magnetized jets. Unlike the standard approach of injecting the jets at large radii, our simulated jets self-consistently form at the source and propagate and accelerate outwards for several orders of magnitude in distance before they interact with the ambient medium. We find that this interaction can trigger strong energy dissipation of two kinds inside the jets, depending on the properties of the ambient medium. Those jets that form in a new outburst and drill a fresh hole through the ambient medium fall victim to a 3D magnetic kink instability and dissipate their energy primarily through magnetic reconnection in the current sheets formed by the instability. On the other hand, those jets that form during repeated cycles of AGN activity and escape through a pre-existing hole in the ambient medium maintain their stability and dissipate their energy primarily at MHD recollimation shocks. In both cases, the dissipation region can be associated with a change in the density profile of the ambient gas. The Bondi radius in AGN jets serves as such a location.

Laboratory studies of volcanic jets

NASA Astrophysics Data System (ADS)

Kieffer, Susan Werner; Sturtevant, Bradford

1984-09-01

The study of the fluid dynamics of violent volcanic eruptions by laboratory experiment is described, and the important fluid-dynamic processes that can be examined in laboratory models are discussed in detail. In preliminary experiments, pure gases are erupted from small reservoirs. The gases used are Freon 12 and Freon 22, two gases of high molecular weight and high density that are good analogs of heavy and particulate-laden volcanic gases; nitrogen, a moderate molecular weight, moderate density gas for which the thermodynamic properties are well known; and helium, a low molecular weight, lowdensity gas that is used as a basis for comparison with the behavior of the heavier gases and as an analog of steam, the gas that dominates many volcanic eruptions. Transient jets erupt from the reservoir into the laboratory upon rupture of a thin diaphragm at the exit of a convergent nozzle. The gas accelerates from rest in the reservoir to high velocity in the jet. Reservoir pressures and geometries are such that the fluid velocity in the jets is initially supersonic and later decays to subsonic. The measured reservoir pressure decreases as the fluid expands through repetitively reflecting rarefaction waves, but for the conditions of these experiments, a simple steady-discharge model is sufficient to explain the pressure decay and to predict the duration of the flow. Density variations in the flow field have been visualized with schlieren and shadowgraph photography. The observed structure of the jet is correlated with the measured pressure history. The starting vortex generated when the diaphragm ruptures becomes the head of the jet. Though the exit velocity is sonic, the flow head in the helium jet decelerates to about one-third of sonic velocity in the first few nozzle diameters, the nitrogen head decelerates to about three-fourths of sonic velocity, while Freon maintains nearly sonic velocity. The impulsive acceleration of reservoir fluid into the surrounding atmosphere

Supersonic Coaxial Jet Experiment for CFD Code Validation

NASA Technical Reports Server (NTRS)

Cutler, A. D.; Carty, A. A.; Doerner, S. E.; Diskin, G. S.; Drummond, J. P.

1999-01-01

A supersonic coaxial jet facility has been designed to provide experimental data suitable for the validation of CFD codes used to analyze high-speed propulsion flows. The center jet is of a light gas and the coflow jet is of air, and the mixing layer between them is compressible. Various methods have been employed in characterizing the jet flow field, including schlieren visualization, pitot, total temperature and gas sampling probe surveying, and RELIEF velocimetry. A Navier-Stokes code has been used to calculate the nozzle flow field and the results compared to the experiment.

Kelvin-Helmholtz instability of stratified jets.

NASA Astrophysics Data System (ADS)

Hanasz, M.; Sol, H.

1996-11-01

We investigate the Kelvin-Helmholtz instability of stratified jets. The internal component (core) is made of a relativistic gas moving with a relativistic bulk speed. The second component (sheath or envelope) flows between the core and external gas with a nonrelativistic speed. Such a two-component jet describes a variety of possible astrophysical jet configurations like e.g. (1) a relativistic electron-positron beam penetrating a classical electron-proton disc wind or (2) a beam-cocoon structure. We perform a linear stability analysis of such a configuration in the hydrodynamic, plane-parallel, vortex-sheet approximation. The obtained solutions of the dispersion relation show very apparent differences with respect to the single-jet solutions. Due to the reflection of sound waves at the boundary between sheet and external gas, the growth rate as a function of wavenumber presents a specific oscillation pattern. Overdense sheets can slow down the growth rate and contribute to stabilize the configuration. Moreover, we obtain the result that even for relatively small sheet widths the properties of sheet start to dominate the jet dynamics. Such effects could have important astrophysical implications, for instance on the origin of the dichotomy between radio-loud and radio-quiet objects.

Techniques for tritium recovery from carbon flakes and dust at the JET active gas handling system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruenhagen, S.; Perevezentsev, A.; Brennan, P. D.

2008-07-15

Detritiation of highly tritium contaminated carbon and metal material used as first wall armour is a key issue for fusion machines like JET and ITER. Re-deposited carbon and hydrogen in the form of flakes and dust can lead to a build-up of the tritium inventory and therefore this material must be removed and processed. The high tritium concentration of the flake and dust material collected from the JET vacuum vessel makes it unsuitable for direct waste disposal without detritiation. A dedicated facility to process the tritiated carbon flake material and recover the tritium has been designed and built. In severalmore » test runs active material was successfully processed and de-tritiated in the new facility. Samples containing only carbon and hydrogen isotopes have been completely oxidized without any residue. Samples containing metallic impurities, e.g. beryllium, require longer processing times, adjusted processing parameters and yield an oxide residue. The detritiation factor was 2x10{sup 4}. In order to simulate in-vessel and ex-vessel detritiation techniques, the detritiation of a carbon flake sample by isotopic exchange in a hydrogen atmosphere was investigated. 2.8% of tritium was recovered by this means. (authors)« less

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.

Rapid Confined Mixing with Transverse Jets Part 1: Single Jet

NASA Astrophysics Data System (ADS)

Salazar, David; Forliti, David

2012-11-01

Transverse jets have been studied extensively due to their relevance and efficiency in fluid mixing applications. Gas turbine burners, film cooling, and chemical reactors are some examples of rapid transverse jet mixing. Motivated by a lack of universal scaling laws for confined and unconfined transverse jets, a newly developed momentum transfer parameter was found to improve correlation of literature data. Jet column drag and entrainment arguments for momentum transfer are made to derive the parameter. A liquid-phase mixing study was conducted to investigate confined mixing for a low number of jets. Planar laser induced fluorescence was implemented to measure mixture fraction for a single confined transverse jet. Time-averaged cross-sectional images were taken with a light sheet located three diameters downstream of transverse injection. A mixture of water and sodium fluorescein was used to distinguish jet fluid from main flow fluid for the test section images. Image data suggest regimes for under- and overpenetration of jet fluid into the main flow. The scaling parameter is found to correlate optimum unmixedness for multiple diameter ratios at a parameter value of 0.75. Distribution A: Public Release, Public Affairs Clearance Number: 12655.

Bibliography of Books and Published Reports on Gas Turbines, Jet Propulsion, and Rocket Power Plants, January 1950 through December 1953

DTIC Science & Technology

1953-12-01

Vt. J. V. Casamassa, Jet aircraft power systems . McGraw-Hill, New York. C. C. Chapel, Jet aircraft simplified. Aero Pubs. Inc., Los Angeles. V. C...combination. NACA Tech. Note No. 1951 (Sept.). A. F. Lietzke and H. M. Henneberry, Evaluation of piston-type gas- generator engine for subsonic transport...Dynamics of a turbojet engine considered as a quasi-static system . NACA Tech. Note No. 2091 (May). A. E. Puckett, Optimum performance of rocket- powered

Investigating the effect of adding an on-axis jet to Ar gas puff Z pinches on Z.

DOE PAGES

Harvey-Thompson, Adam James; Jennings, Christopher Ashley; Jones, Brent M.; ...

2016-10-20

Double-shell Ar gas puff implosions driven by 16.5±0.5 MA on the Z generator at Sandia National Laboratories are very effective emitters of Ar K-shell radiation (photon energy >3 keV), producing yields of 330 ± 9% kJ (B. Jones et al., Phys. Plasmas, 22, 020706, 2015). In addition, previous simulations and experiments have reported dramatic increases in K-shell yields when adding an on-axis jet to double shell gas puffs for some configurations.

Platelet activating factor receptor binding plays a critical role in jet fuel-induced immune suppression.

PubMed

Ramos, Gerardo; Kazimi, Nasser; Nghiem, Dat X; Walterscheid, Jeffrey P; Ullrich, Stephen E

2004-03-15

Applying military jet fuel (JP-8) or commercial jet fuel (Jet-A) to the skin of mice suppresses the immune response in a dose-dependent manner. The release of biological response modifiers, particularly prostaglandin E2 (PGE2), is a critical step in activating immune suppression. Previous studies have shown that injecting selective cyclooxygenase-2 inhibitors into jet fuel-treated mice blocks immune suppression. Because the inflammatory phospholipid mediator, platelet-activating factor (PAF), up-regulates cyclooxygenase-2 production and PGE2 synthesis by keratinocytes, we tested the hypothesis that PAF-receptor binding plays a role in jet fuel-induced immune suppression. Treating keratinocyte cultures with PAF and/or jet fuel (JP-8 and Jet-A) stimulates PGE2 secretion. Jet fuel-induced PGE2 production was suppressed by treating the keratinocytes with specific PAF-receptor antagonists. Injecting mice with PAF, or treating the skin of the mice with JP-8, or Jet-A, induced immune suppression. Jet fuel-induced immune suppression was blocked when the jet fuel-treated mice were injected with PAF-receptor antagonists before treatment. Jet fuel treatment has been reported to activate oxidative stress and treating the mice with anti-oxidants (Vitamins C, or E or beta-hydroxy toluene), before jet fuel application, interfered with immune suppression. These findings confirm previous studies showing that PAF-receptor binding can modulate immune function. Furthermore, they suggest that PAF-receptor binding may be an early event in the induction of immune suppression by immunotoxic environmental agents that target the skin.

Gas dynamics of a supersonic radial jet. Part II

NASA Astrophysics Data System (ADS)

Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

2016-05-01

The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

Soot Formation in Hydrocarbon/Air Laminar Jet Diffusion Flames

NASA Technical Reports Server (NTRS)

Sunderland, P. B.; Faeth, G. M.

1994-01-01

Soot processes within hydrocarbon/air diffusion flames are important because they affect the durability and performance of propulsion systems, the hazards of unwanted fires, the pollutant and particulate emissions from combustion processes, and the potential for developing computational combustion. Motivated by these observations, this investigation involved an experimental study of the structure and soot properties of round laminar jet diffusion flames, seeking an improved understanding of soot formation (growth and nucleation) within diffusion flames. The present study extends earlier work in this laboratory concerning laminar smoke points (l) and soot formation in acetylene/air laminar jet diffusion flames (2), emphasizing soot formation in hydrocarbon/air laminar jet diffusion flames for fuels other than acetylene. In the flame system, acetylene is the dominant gas species in the soot formation region and both nucleation and growth were successfully attributed to first-order reactions of acetylene, with nucleation exhibiting an activation energy of 32 kcal/gmol while growth involved negligible activation energy and a collision efficiency of O.53%. In addition, soot growth in the acetylene diffusion flames was comparable to new soot in premixed flame (which also has been attributed to first-order acetylene reactions). In view of this status, a major issue is the nature of soot formation processes in diffusion flame involving hydrocarbon fuels other than acetylene. In particular, information is needed about th dominant gas species in the soot formation region and the impact of gas species other than acetylene on soot nucleation and growth.

The Jet-driven Outflow in the Radio Galaxy SDSS J1517+3353: Implications for Double-peaked Narrow-line Active Galactic Nucleus

NASA Astrophysics Data System (ADS)

Rosario, D. J.; Shields, G. A.; Taylor, G. B.; Salviander, S.; Smith, K. L.

2010-06-01

We report on the study of an intriguing active galaxy that was selected as a potential multiple supermassive black hole merger in the early-type host SDSS J151709.20+335324.7 (z = 0.135) from a complete search for double-peaked [O III] lines from the SDSS spectroscopic quasi-stellar object (QSO) database. Ground-based SDSS imaging reveals two blue structures on either side of the photometric center of the host galaxy, separated from each other by about 5.7 kpc. From a combination of SDSS fiber and Keck/HIRES long-slit spectroscopy, it is demonstrated that, in addition to these two features, a third distinct structure surrounds the nucleus of the host galaxy. All three structures exhibit highly ionized line emission with line ratios characteristic of Seyfert II active galactic nuclei. The analysis of spatially resolved emission-line profiles from the HIRES spectrum reveal three distinct kinematic subcomponents, one at rest and the other two moving at -350 km s-1 and 500 km s-1 with respect to the systemic velocity of the host galaxy. A comparison of imaging and spectral data confirm a strong association between the kinematic components and the spatial knots, which implies a highly disturbed and complex active region in this object. A comparative analysis of the broadband positions, colors, kinematics, and spectral properties of the knots in this system lead to two plausible explanations: (1) a multiple active galactic nucleus (AGN) produced due to a massive dry merger, or (2) a very powerful radio jet-driven outflow. Subsequent VLA radio imaging reveals a clear jet aligned with the emission-line gas, confirming the latter explanation. We use the broadband radio measurements to examine the impact of the jet on the interstellar medium of the host galaxy, and find that the energy in the radio lobes can heat a significant fraction of the gas to the virial temperature. Finally, we discuss tests that may help future surveys distinguish between jet-driven kinematics and

Atmospheric-pressure plasma jet

DOEpatents

Selwyn, Gary S.

1999-01-01

Atmospheric-pressure plasma jet. A .gamma.-mode, resonant-cavity plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two concentric cylindrical electrodes are employed to generate a plasma in the annular region therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly shaping the rf-powered electrode. Because of the atmospheric pressure operation, no ions survive for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike low-pressure plasma sources and conventional plasma processing methods.

A gigantic coronal jet ejected from a compact active region in a coronal hole

NASA Technical Reports Server (NTRS)

Shibata, K.; Nitta, N.; Strong, K. T.; Matsumoto, R.; Yokoyama, T.; Hirayama, T.; Hudson, H.; Ogawara, Y.

1994-01-01

A gigantic coronal jet greater than 3 x 10(exp 5) km long (nearly half the solar radius) has been found with the soft X-ray telescope (SXT) on board the solar X-ray satellite, Yohkoh. The jet was ejected on 1992 January 11 from an 'anemone-type' active region (AR) appearing in a coronal hole and is one of the largest coronal X-ray jets observed so far by SXT. This gigantic jet is the best observed example of many other smaller X-ray jets, because the spatial structures of both the jet and the AR located at its base are more easily resolved. The range of apparent translational velocities of the bulk of the jet was between 90 and 240 km s(exp -1), with the corresponding kinetic energy estimated to be of order of 10(exp 28) ergs. A detailed analysis reveals that the jet was associated with a loop brightening (a small flare) that occurred in the active region. Several features of this observation suggest and are consistent with a magnetic reconnection mechanism for the production of such a 'jet-loop-brightening' event.

The Mochi LabJet Experiment for Measurements of Canonical Helicity Injection in a Laboratory Astrophysical Jet

NASA Astrophysics Data System (ADS)

You, Setthivoine; von der Linden, Jens; Sander Lavine, Eric; Carroll, Evan Grant; Card, Alexander; Quinley, Morgan; Azuara-Rosales, Manuel

2018-06-01

The Mochi device is a new pulsed power plasma experiment designed to produce long, collimated, stable, magnetized plasma jets when set up in the LabJet configuration. The LabJet configuration aims to simulate an astrophysical jet in the laboratory by mimicking an accretion disk threaded by a poloidal magnetic field with concentric planar electrodes in front of a solenoidal coil. The unique setup consists of three electrodes, each with azimuthally symmetric gas slits. Two of the electrodes are biased independently with respect to the third electrode to control the radial electric field profile across the poloidal bias magnetic field. This design approximates a shear azimuthal rotation profile in an accretion disk. The azimuthally symmetric gas slits provide a continuously symmetric mass source at the footpoint of the plasma jet, so any azimuthal rotation of the plasma jet is not hindered by a discrete number of gas holes. The initial set of diagnostics consists of current Rogowski coils, voltage probes, magnetic field probe arrays, an interferometer and ion Doppler spectroscopy, supplemented by a fast ion gauge and a retarding grid energy analyzer. The measured parameters of the first plasmas are ∼1022 m‑3, ∼0.4 T, and 5–25 eV, with velocities of ∼20–80 km s‑1. The combination of a controllable electric field profile, a flared poloidal magnetic field, and azimuthally symmetric mass sources in the experiment successfully produces short-lived (∼10 μs, ≳5 Alfvén times) collimated magnetic jets with a ∼10:1 aspect ratio and long-lived (∼100 μs, ≳40 Alfvén times) flow-stabilized, collimated, magnetic jets with a ∼30:1 aspect ratio.

EDITORIAL: Plasma jets and plasma bullets Plasma jets and plasma bullets

NASA Astrophysics Data System (ADS)

Kong, M. G.; Ganguly, B. N.; Hicks, R. F.

2012-06-01

to 1990 with only 31 papers per year on average, and a total of some 1300 papers, precedes a considerable growth of some 35-50% in research activity every five years, over the last 20 years or so. As shown in the table, the annual dissemination of the field is more than 1600 papers and the total number of papers is in excess of 20000. This upwards trajectory is typical of a strong and growing subject area in physical science, with considerable capacity in both fundamental science and applications. PeriodNumber of papersPapers per annum 1948-1990130031 1991-19952279456 1996-20003447689 2001-20054571914 2006-201066401328 2011 1658 In many of the dense plasma jets discussed above, strong physical forces generated by the plasma are often desired and this favours plasma generation at elevated gas pressure, including atmospheric pressure, which favours a high level of gas ionization. Historically it has been challenging to reduce and control the strong physical forces in high-pressure plasmas for applications where these are unwanted, for example, surface modification of polymeric sheets [5]. Indeed, there is a real need for a vast range of material processing applications at temperatures below 100oC (or below 400 K) and this favours atmospheric-pressure plasma jets sustained far from thermal equilibrium with the dissipated electrical energy largely used not in heat generation but in unleashing non-equilibrium chemical reactions. The long-standing difficulty of effectively controlling the level of gas ionization at atmospheric pressure was overcome by the technological breakthrough of achieving atmospheric-pressure glow discharges in the late 1980s [6]. A related challenge stemming from high collisionality of atmospheric-pressure plasmas (v >> ω0) means that large-area plasmas sustained between parallel-plate electrodes are very susceptible to strong plasma instabilities when molecular gases are introduced for processing applications. This led to an effective

The Stability of Radiatively Cooling Jets I. Linear Analysis

NASA Technical Reports Server (NTRS)

Hardee, Philip E.; Stone, James M.

1997-01-01

The results of a spatial stability analysis of a two-dimensional slab jet, in which optically thin radiative cooling is dynamically important, are presented. We study both magnetized and unmagnetized jets at external Mach numbers of 5 and 20. We model the cooling rate by using two different cooling curves: one appropriate to interstellar gas, and the other to photoionized gas of reduced metallicity. Thus, our results will be applicable to both protostellar (Herbig-Haro) jets and optical jets from active galactic nuclei. We present analytical solutions to the dispersion relations in useful limits and solve the dispersion relations numerically over a broad range of perturbation frequencies. We find that the growth rates and wavelengths of the unstable Kelvin-Helmholtz (K-H) modes are significantly different from the adiabatic limit, and that the form of the cooling function strongly affects the results. In particular, if the cooling curve is a steep function of temperature in the neighborhood of the equilibrium state, then the growth of K-H modes is reduced relative to the adiabatic jet. On the other hand, if the cooling curve is a shallow function of temperature, then the growth of K-H modes can be enhanced relative to the adiabatic jet by the increase in cooling relative to heating in overdense regions. Inclusion of a dynamically important magnetic field does not strongly modify the important differences between an adiabatic jet and a cooling jet, provided the jet is highly supermagnetosonic and not magnetic pressure-dominated. In the latter case, the unstable modes behave more like the transmagnetosonic magnetic pressure-dominated adiabatic limit. We also plot fluid displacement surfaces associated with the various waves in a cooling jet in order to predict the structures that might arise in the nonlinear regime. This analysis predicts that low-frequency surface waves and the lowest order body modes will be the most effective at producing observable features in

Control of jet noise

NASA Technical Reports Server (NTRS)

Schreck, Stefan

1992-01-01

To investigate the possibility of active control of jet noise, knowledge of the noise generation mechanisms in natural jets is essential. Once these mechanisms are determined, active control can be used to manipulate the noise production processes. We investigated the evolution of the flow fields and the acoustic fields of rectangular and circular jets. A predominant flapping mode was found in the supersonic rectangular jets. We hope to increase the spreading of supersonic jets by active control of the flapping mode found in rectangular supersonic jets.

[Kelvin-Helmholtz instability in protostellar jets

NASA Technical Reports Server (NTRS)

Stone, James; Hardee, Philip

1996-01-01

NASA grant NAG 5 2866, funded by the Astrophysics Theory Program, enabled the study the Kelvin-Helmholtz instability in protostellar jets. In collaboration with co-investigator Philip Hardee, the PI derived the analytic dispersion relation for the instability in including a cooling term in the energy equation which was modeled as one of two different power laws. Numerical solutions to this dispersion relation over a wide range of perturbation frequencies, and for a variety of parameter values characterizing the jet (such as Mach number, and density ratio) were found It was found that the growth rates and wavelengths associated with unstable roots of the dispersion relation in cooling jets are significantly different than those associated with adiabatic jets, which have been studied previously. In collaboration with graduate student Jianjun Xu (funded as a research associate under this grant), hydrodynamical simulations were used to follow the growth of the instability into the nonlinear regime. It was found that asymmetric surface waves lead to large amplitude, sinusoidal distortions of the jet, and ultimately to disruption Asymmetric body waves, on the other hand, result in the formation of shocks in the jet beam in the nonlinear regime. In cooling jets, these shocks lead to the formation of dense knots and filaments of gas within the jet. For sufficiently high perturbation frequencies, however, the jet cannot respond and it remains symmetric. Applying these results to observed systems, such as the Herbig-Haro jets HH34, HH111 and HH47 which have been observed with the Hubble Space Telescope, we predicted that some of the asymmetric structures observed in these systems could be attributed to the K-H modes, but that perturbations on timescales associated with the inner disk (about 1 year) would be too rapid to cause disruption. Moreover, it was discovered that weak shock 'spurs' in the ambient gas produced by ripples in the jet surface due to nonlinear, modes of

Effects of Jet Fuel Spills on the Microbial Community of Soil †

PubMed Central

Song, Hong-Gyu; Bartha, Richard

1990-01-01

Hydrocarbon residues, microbial numbers, and microbial activity were measured and correlated in loam soil contaminated by jet fuel spills resulting in 50 and 135 mg of hydrocarbon g of soil−1. Contaminated soil was incubated at 27°C either as well-aerated surface soil or as poorly aerated subsurface soil. In the former case, the effects of bioremediation treatment on residues, microbial numbers, and microbial activity were also assessed. Hydrocarbon residues were measured by quantitative gas chromatography. Enumerations included direct counts of metabolically active bacteria, measurement of mycelial length, plate counts of aerobic heterotrophs, and most probable numbers of hydrocarbon degraders. Activity was assessed by fluorescein diacetate (FDA) hydrolysis. Jet fuel disappeared much more rapidly from surface soil than it did from subsurface soil. In surface soil, microbial numbers and mycelial length were increased by 2 to 2.5 orders of magnitude as a result of jet fuel contamination alone and by 3 to 4 orders of magnitude as a result of the combination of jet fuel contamination and bioremediation. FDA hydrolysis was stimulated by jet fuel and bioremediation, but was inhibited by jet fuel alone. The latter was traced to an inhibition of the FDA assay by jet fuel biodegradation products. In subsurface soil, oxygen limitation strongly attenuated microbial responses to jet fuel. An increase in the most probable numbers of hydrocarbon degraders was accompanied by a decline in other aerobic heterotrophs, so that total plate counts changed little. The correlations between hydrocarbon residues, microbial numbers, and microbial activity help in elucidating microbial contributions to jet fuel elimination from soil. PMID:16348138

Jet-ISM Interaction in the Radio Galaxy 3C 293: Jet-driven Shocks Heat ISM to Power X-Ray and Molecular H2 Emission

NASA Astrophysics Data System (ADS)

Lanz, L.; Ogle, P. M.; Evans, D.; Appleton, P. N.; Guillard, P.; Emonts, B.

2015-03-01

We present a 70 ks Chandra observation of the radio galaxy 3C 293. This galaxy belongs to the class of molecular hydrogen emission galaxies (MOHEGs) that have very luminous emission from warm molecular hydrogen. In radio galaxies, the molecular gas appears to be heated by jet-driven shocks, but exactly how this mechanism works is still poorly understood. With Chandra, we observe X-ray emission from the jets within the host galaxy and along the 100 kpc radio jets. We model the X-ray spectra of the nucleus, the inner jets, and the X-ray features along the extended radio jets. Both the nucleus and the inner jets show evidence of 107 K shock-heated gas. The kinetic power of the jets is more than sufficient to heat the X-ray emitting gas within the host galaxy. The thermal X-ray and warm H2 luminosities of 3C 293 are similar, indicating similar masses of X-ray hot gas and warm molecular gas. This is consistent with a picture where both derive from a multiphase, shocked interstellar medium (ISM). We find that radio-loud MOHEGs that are not brightest cluster galaxies (BCGs), like 3C 293, typically have LH2/LX˜ 1 and MH2/MX˜ 1, whereas MOHEGs that are BCGs have LH2/LX˜ 0.01 and MH2/MX˜ 0.01. The more massive, virialized, hot atmosphere in BCGs overwhelms any direct X-ray emission from current jet-ISM interaction. On the other hand, LH2/LX˜ 1 in the Spiderweb BCG at z = 2, which resides in an unvirialized protocluster and hosts a powerful radio source. Over time, jet-ISM interaction may contribute to the establishment of a hot atmosphere in BCGs and other massive elliptical galaxies.

Effect of DC magnetic field on atmospheric pressure argon plasma jet

NASA Astrophysics Data System (ADS)

Safari, R.; Sohbatzadeh, F.

2015-05-01

In this work, external DC magnetic field effect on the atmospheric pressure plasma jet has been investigated, experimentally. The magnetic field has been produced using a Helmholtz coil configuration. It has been applied parallel and transverse to the jet flow. The strength of the DC magnetic field is 0-0.28 and 0-0.57 Tesla between the two coils in parallel and transverse applications, respectively. It has been shown that the plasma gas flow plays the main role in magneto-active collision-dominated plasma. The effect of plasma fluid velocity on the jet emission has been discussed, qualitatively. It has been observed that the external DC magnetic field has different trends in parallel and transverse applications. The measurements reveal that the plasma jet irradiance increases in parallel field, while it decreases in transverse field. The former has been attributed to increasing plasma number density and the latter to loss of plasma species that reduces the magneto-plasma jet irradiance and in turn shrinks plasma jet number density. As a result, the plasma fluid velocity is responsible for such trends though the magneto-active plasma remains isotropic.

A Series of Jets that Drove Streamer-Puff CMEs from Giant Active Region of 2014

NASA Technical Reports Server (NTRS)

Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

We investigate characteristics of solar coronal jets that originated from active region NOAA 12192 and produced coronal mass ejections (CMEs). This active region produced many non­-jet major flare eruptions (X and M class) that made no CME. A multitude of jets occurred from the southeast edge of the active region, and in contrast to the major-­flare eruptions in the core, six of these jets resulted in CMEs. Our jet observations are from SDO/AIA EUV channels and from Hinode/XRT, and CME observations are from the SOHO/LASCO C2 coronograph. Each jet-­driven CME was relatively slow-­moving (approx. 200 - 300 km/s) compared to most CMEs; had angular width (20deg - 50deg) comparable to that of the streamer base; and was of the "streamer­-puff" variety, whereby a pre-existing streamer was transiently inflated but not removed (blown out) by the passage of the CME. Much of the chromospheric-­temperature plasma of the jets producing the CMEs escaped from the Sun, whereas relatively more of the chromospheric plasma in the non-CME-producing jets fell back to the solar surface. We also found that the CME-producing jets tended to be faster in speed and longer in duration than the non-CME-­producing jets. We expect that the jets result from eruptions of mini-filaments. We further propose that the CMEs are driven by magnetic twist injected into streamer-­base coronal loops when erupting twisted mini-filament field reconnects with the ambient field at the foot of those loops.

A Series of Jets that Drove Streamer-Puff CMEs from Giant Active Region of 2014

NASA Technical Reports Server (NTRS)

Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L.

2016-01-01

We investigate characteristics of solar coronal jets that originated from active region NOAA 12192 and produced coronal mass ejections (CMEs). This active region produced many non-jet major flare eruptions (X and M class) that made no CME. A multiitude of jets occurred from the southeast edge of the active region, and in contrast to the major-flare eruptions in the core, six of these jets resulted in CMEs. Our jet observations are from multiple SDO/AIA EUV channels, including 304, 171 and 193 Angstrom, and CME observations are taken from SOHO/LASCO C2 coronograph. Each jet-driven CME was relatively slow-moving (approximately 200 - 300 km s(sup-1) compared to most CMEs; had angular width (20deg - 50deg) comparable to that of the streamer base; and was of the "streamer-puff" variety, whereby a preexisting streamer was transiently inflated but not removed (blown out) by the passage of the CME. Much of the chromospheric-temperature plasma of the jets producing the CMEs escaped from the Sun, whereas relatively more of the chromospheric plasma in the non-CME-producing jets fell back to the solar surface. We also found that the CME-producing jets tended to be faster in speed and longer in duration than the non-CME-producing jets. We expect that the jets result from eruptions of mini-filaments. We further propose that the CMEs are driven by magnetic twist injected into streamer-base coronal loops when erupting twisted mini-filament field reconnects with the ambient field at the foot of those loops.

Hydrocarbon bio-jet fuel from bioconversion of poplar biomass: life cycle assessment.

PubMed

Budsberg, Erik; Crawford, Jordan T; Morgan, Hannah; Chin, Wei Shan; Bura, Renata; Gustafson, Rick

2016-01-01

Bio-jet fuels compatible with current aviation infrastructure are needed as an alternative to petroleum-based jet fuel to lower greenhouse gas emissions and reduce dependence on fossil fuels. Cradle to grave life cycle analysis is used to investigate the global warming potential and fossil fuel use of converting poplar biomass to drop-in bio-jet fuel via a novel bioconversion platform. Unique to the biorefinery designs in this research is an acetogen fermentation step. Following dilute acid pretreatment and enzymatic hydrolysis, poplar biomass is fermented to acetic acid and then distilled, hydroprocessed, and oligomerized to jet fuel. Natural gas steam reforming and lignin gasification are proposed to meet hydrogen demands at the biorefineries. Separate well to wake simulations are performed using the hydrogen production processes to obtain life cycle data. Both biorefinery designs are assessed using natural gas and hog fuel to meet excess heat demands. Global warming potential of the natural gas steam reforming and lignin gasification bio-jet fuel scenarios range from CO2 equivalences of 60 to 66 and 32 to 73 g MJ(-1), respectively. Fossil fuel usage of the natural gas steam reforming and lignin gasification bio-jet fuel scenarios range from 0.78 to 0.84 and 0.71 to 1.0 MJ MJ(-1), respectively. Lower values for each impact category result from using hog fuel to meet excess heat/steam demands. Higher values result from using natural gas to meet the excess heat demands. Bio-jet fuels produced from the bioconversion of poplar biomass reduce the global warming potential and fossil fuel use compared with petroleum-based jet fuel. Production of hydrogen is identified as a major source of greenhouse gas emissions and fossil fuel use in both the natural gas steam reforming and lignin gasification bio-jet simulations. Using hog fuel instead of natural gas to meet heat demands can help lower the global warming potential and fossil fuel use at the biorefineries.

An Investigation of Transonic Flow Fields Surrounding Hot and Cold Sonic Jets

NASA Technical Reports Server (NTRS)

Lee, George

1961-01-01

An investigation at free-stream Mach numbers of 0.90 t o 1.10 was made to determine (1) the jet boundaries and the flow fields around hot and cold jets, and (2) whether a cold-gas jet could adequately simulate the boundary and flow field of hot-gas jet. Schlieren photographs and static-pressure surveys were taken in the vacinity of a sonic jet which was operated over a range of jet pressure ratios of 1 to 6, specific heat ratios at the nozzle exit of 1.29 and 1.40, and jet temperatures up to 2600 R.

HOMOLOGOUS JET-DRIVEN CORONAL MASS EJECTIONS FROM SOLAR ACTIVE REGION 12192

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panesar, Navdeep K.; Sterling, Alphonse C.; Moore, Ronald L., E-mail: navdeep.k.panesar@nasa.gov

We report observations of homologous coronal jets and their coronal mass ejections (CMEs) observed by instruments onboard the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO) spacecraft. The homologous jets originated from a location with emerging and canceling magnetic field at the southeastern edge of the giant active region (AR) of 2014 October, NOAA 12192. This AR produced in its interior many non-jet major flare eruptions (X- and M- class) that made no CME. During October 20 to 27, in contrast to the major flare eruptions in the interior, six of the homologous jets from the edgemore » resulted in CMEs. Each jet-driven CME (∼200–300 km s{sup −1}) was slower-moving than most CMEs, with angular widths (20°–50°) comparable to that of the base of a coronal streamer straddling the AR and were of the “streamer-puff” variety, whereby the preexisting streamer was transiently inflated but not destroyed by the passage of the CME. Much of the transition-region-temperature plasma in the CME-producing jets escaped from the Sun, whereas relatively more of the transition-region plasma in non-CME-producing jets fell back to the solar surface. Also, the CME-producing jets tended to be faster and longer-lasting than the non-CME-producing jets. Our observations imply that each jet and CME resulted from reconnection opening of twisted field that erupted from the jet base and that the erupting field did not become a plasmoid as previously envisioned for streamer-puff CMEs, but instead the jet-guiding streamer-base loop was blown out by the loop’s twist from the reconnection.« less

Overexpanded viscous supersonic jet interacting with a unilateral barrier

NASA Astrophysics Data System (ADS)

Dobrynin, B. M.; Maslennikov, V. G.; Sakharov, V. A.; Serova, E. V.

1986-07-01

The interaction of a two-dimensional supersonic jet with a unilateral barrier parallel to the flow symmetry plane was studied to account for effects due to gas viscosity and backgound-gas ejection from the region into which the jet expands. In the present experiments, the incident shock wave was reflected at the end of a shock tube equipped with a nozzle. The jet emerged into a pressure chamber 6 cu m in volume and the environmental pressure ratio of the flow in the quasi-stationary phase remained constant. The light source was an OGM-20 laser operating in the giant-pulse mode. Due to background-gas ejection, the gas density in the vicinity of the barrier is much less than on the unconfined side of the jet. The resulting flow is characterized by two distinct environmental pressure ratios: the flow is underexpanded near the barrier, while on the other side it is overexpanded.

Comparing different Ultraviolet Imaging Spectrograph (UVIS) occultation observations using modeling of water vapor jets

NASA Astrophysics Data System (ADS)

Portyankina, Ganna; Esposito, Larry W.; Hansen, Candice; Aye, Klaus-Michael

2016-10-01

Motivation: On March 11, 2016 the Cassini UVIS observed its 6th star occultation by Enceladus' plume. This observation was aimed to determine variability in the total gas flux from the Enceladus' southern polar region. The analysis of the received data suggests that the total gas flux is moderately increased comparing to the average gas flux observed by UVIS from 2005 to 2011 [1]. However, UVIS detected variability in individual jets. In particular, Baghdad 1 is more collimated in 2016 than in 2005, meaning its gas escapes at higher velocity.Model and fits: We use 3D DSMC model for water vapor jets to compare different UVIS occultation observations from 2005 to 2016. The model traces test articles from jets' sources [2] into space and results in coordinates and velocities for a set of test particles. We convert particle positions into the particle number density and integrate along UVIS line of sight (LoS) for each time step of the UVIS observation using precise observational geometry derived from SPICE [3]. We integrate all jets that are crossed by the LoS and perform constrained least-squares fit of resulting modeled opacities to the observed data to solved for relative strengths of jets. The geometry of each occultation is specific, for example, during solar occultation in 2010 UVIS LoS was almost parallel to tiger stripes, which made it possible to distinguish jets venting from different tiger stripes. In 2011 Eps Orionis occultation LoS was perpendicular to tiger stripes and thus many of the jets were geometrically overlapping. Solar occultation provided us with the largest inventory of active jets - our model fit detects at least 43 non-zero jet contributions. Stellar occultations generally have lower temporal resolution and observe only a sub-set of these jets: 2011 Eps Orionis needs minimum 25 non-zero jets to fit UVIS data. We will discuss different occultations and models fits, including the most recent Epsilon Orionis occultation of 2016.[1] Hansen et al

The Stability of Radiatively Cooling Jets. 2: Nonlinear Evolution

NASA Technical Reports Server (NTRS)

Stone, James M.; Xu, Jianjun; Hardee, Philip

1997-01-01

We use two-dimensional time-dependent hydrodynamical simulations to follow the growth of the Kelvin-Helmholtz (K-H) instability in cooling jets into the nonlinear regime. We focus primarily on asymmetric modes that give rise to transverse displacements of the jet beam. A variety of Mach numbers and two different cooling curves are studied. The growth rates of waves in the linear regime measured from the numerical simulations are in excellent agreement with the predictions of the linear stability analysis presented in the first paper in this series. In the nonlinear regime, the simulations show that asymmetric modes of the K-H instability can affect the structure and evolution of cooling jets in a number of ways. We find that jets in which the growth rate of the sinusoidal surface wave has a maximum at a so-called resonant frequency can be dominated by large-amplitude sinusoidal oscillations near this frequency. Eventually, growth of this wave can disrupt the jet. On the other hand, nonlinear body waves tend to produce low-amplitude wiggles in the shape of the jet but can result in strong shocks in the jet beam. In cooling jets, these shocks can produce dense knots and filaments of cooling gas within the jet. Ripples in the surface of the jet beam caused by both surface and body waves generate oblique shock "spurs" driven into the ambient gas. Our simulations show these shock "spurs" can accelerate ambient gas at large distances from the jet beam to low velocities, which represents a new mechanism by which low-velocity bipolar outflows may be driven by high-velocity jets. Rapid entrainment and acceleration of ambient gas may also occur if the jet is disrupted. For parameters typical of protostellar jets, the frequency at which K-H growth is a maximum (or highest frequency to which the entire jet can respond dynamically) will be associated with perturbations with a period of - 200 yr. Higher frequency (shorter period) perturbations excite waves associated with body

The AGHS at JET and preparations for a future DT campaign

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R.; JET-EFDA, Culham Science Centre, Abingdon

2015-03-15

The Active Gas Handling System (AGHS) at JET is a unique facility enabling JET to perform reactor like, DT operations. As a future DT experimental campaign (DTE2) is scheduled for 2017 this paper provides a brief overview of the AGHS and a summary of ongoing work supporting the currently JET experimental campaign. In order to improve tritium accountancy a solid state based detector for tritium is being developed. Another important upgrade concerns tritium injection, 4 existing GIMs (Tritium Gas Introduction Module) will inject a mix of D and T rather than T{sub 2} in the divertor region rather than inmore » the torus mid plane enabling a far better control and variability of the introduction of tritium into the plasma. An overview of the scale of DTE2 is included as well as an example of some of the upgrades currently being undertaken to fully exploit the learning opportunities for ITER and DEMO DTE2 provides. (authors)« less

Single-jet gas cooling of in-beam foils or specimens: Prediction of the convective heat-transfer coefficient

NASA Astrophysics Data System (ADS)

Steyn, Gideon; Vermeulen, Christiaan

2018-05-01

An experiment was designed to study the effect of the jet direction on convective heat-transfer coefficients in single-jet gas cooling of a small heated surface, such as typically induced by an accelerated ion beam on a thin foil or specimen. The hot spot was provided using a small electrically heated plate. Heat-transfer calculations were performed using simple empirical methods based on dimensional analysis as well as by means of an advanced computational fluid dynamics (CFD) code. The results provide an explanation for the observed turbulent cooling of a double-foil, Havar beam window with fast-flowing helium, located on a target station for radionuclide production with a 66 MeV proton beam at a cyclotron facility.

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic Binary System R Aqr

NASA Astrophysics Data System (ADS)

Karovska, Margarita

2016-09-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of multi-scale components of the powerful jet; from near the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond , and especially of the recently discovered inner jet, to gain insight on early jet formation and propagation, such as jet kinematics and precession.

Direct current plasma jet at atmospheric pressure operating in nitrogen and air

NASA Astrophysics Data System (ADS)

Deng, X. L.; Nikiforov, A. Yu.; Vanraes, P.; Leys, Ch.

2013-01-01

An atmospheric pressure direct current (DC) plasma jet is investigated in N2 and dry air in terms of plasma properties and generation of active species in the active zone and the afterglow. The influence of working gases and the discharge current on plasma parameters and afterglow properties are studied. The electrical diagnostics show that discharge can be sustained in two different operating modes, depending on the current range: a self-pulsing regime at low current and a glow regime at high current. The gas temperature and the N2 vibrational temperature in the active zone of the jet and in the afterglow are determined by means of emission spectroscopy, based on fitting spectra of N2 second positive system (C3Π-B3Π) and the Boltzmann plot method, respectively. The spectra and temperature differences between the N2 and the air plasma jet are presented and analyzed. Space-resolved ozone and nitric oxide density measurements are carried out in the afterglow of the jet. The density of ozone, which is formed in the afterglow of nitrogen plasma jet, is quantitatively detected by an ozone monitor. The density of nitric oxide, which is generated only in the air plasma jet, is determined by means of mass-spectroscopy techniques.

Multiwavelength Study of Powerful New Jet Activity in the Symbiotic System R AQR

NASA Astrophysics Data System (ADS)

Karovska, Margarita

2016-10-01

We propose to carry out coordinated high-spatial resolution Chandra ACIS-S and multiwavelength (UV-Optical) HST/WFC3 observations of R Aqr, a very active symbiotic interacting binary system. Our main goal is to study the physical characteristics of the multi-scale components of the powerful jet; from the vicinity of the central binary (within a few AU) to the jet-circumbinary material interaction region (2500 AU) and beyond, and especially of the recently discovered new component of the inner jet (likely due to recent ejection of material). Our main goal is to gain new insight on early jet formation and propagation, including jet kinematics and precession.

STOL landing thrust: Reverser jet flowfields

NASA Technical Reports Server (NTRS)

Kotansky, D. R.; Glaze, L. W.

1987-01-01

Analysis tools and modeling concepts for jet flow fields encountered upon use of thrust reversers for high performance military aircraft are described. A semi-empirical model of the reverser ground wall jet interaction with the uniform cross flow due to aircraft forward velocity is described. This ground interaction model is used to demonstrate exhaust gas ingestion conditions. The effects of control of exhaust jet vector angle, lateral splay, and moving versus fixed ground simulation are discussed. The Adler/Baron jet-in-cross flow model is used in conjunction with three dimensional panel methods to investigate the upper surface jet induced flow field.

Effects of the electrical parameters and gas flow rate on the generation of reactive species in liquids exposed to atmospheric pressure plasma jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, Eun Jeong; Joh, Hea Min; Kim, Sun Ja

2016-07-15

In this work, an atmospheric pressure plasma jet was fabricated and studied for plasma–liquid interactions. The plasma jet consists of a quartz-covered pin electrode and outer quartz tube with a tapered nozzle. Using the current–voltage (I-V) and optical emission characteristics of the plasma jet, the plasma density and the speed of the plume were investigated. The optical emission spectra clearly indicated the excited NO, O, OH, N{sub 2}, and N{sub 2}{sup +} in the plasma plumes. Then the plasma jets were applied to the deionized water. We investigated the effects of the operating parameters such as applied voltage, pulse frequency,more » and gas flow rate on the generation of reactive species in the gas and liquid phases. The densities of reactive species including OH radicals were obtained at the plasma–liquid surface and inside the plasma-treated liquids using ultraviolet absorption spectroscopy and chemical probe method. The nitrite concentration was detected by Griess assay. The data are very suggestive that there is a strong correlation among the production of reactive oxygen and nitrogen species (RONS) in the plasmas and liquids.« less

An Experimental and CFD Study of a Supersonic Coaxial Jet

NASA Technical Reports Server (NTRS)

Cutler, A. D.; White, J. A.

2001-01-01

A supersonic coaxial jet facility is designed and experimental data are acquired suitable for the validation of CFD codes employed in the analysis of high-speed air-breathing engines. The center jet is of a light gas, the coflow jet is of air, and the mixing layer between them is compressible. The jet flow field is characterized using schlieren imaging, surveys with pitot, total temperature and gas sampling probes, and RELIEF velocimetry. VULCAN, a structured grid CFD code, is used to solve for the nozzle and jet flow, and the results are compared to the experiment for several variations of the kappa - omega turbulence model

Cometary Jet Collimation Without Physical Confinement

NASA Astrophysics Data System (ADS)

Steckloff, J. K.; Melosh, H. J.

2012-12-01

Recent high-resolution images of comet nuclei reveal that gases and dust expelled by the comet are organized into narrow jets. Contemporary models postulate that these jets collimate when the expanding gases and dust pass through a physical aperture or nozzle. However, recent high-resolution spacecraft observations fail to detect such apertures on cometary surfaces. Furthermore, these models do not explain why cometary jets appear to be directed normal to the local gravitational potential, and/or appear to originate on the faces of scarps. Additionally, observations of comet nuclei by visiting spacecraft have observed that jet activity is tied to the diurnal rotation of the comet. This suggests that jet emissions are powered by the sun, and therefore must emanate from close to the surface of the comet due to a thermal skin depth on the order of ~10 cm. Here we describe a simplified computer model of jets emanating from Comet Tempel 1. Our novel mechanism is based on the occurrence of fluidized flows, which have gained observational support from the Deep Impact and Stardust-NExT flyby missions We approximate the vents of the comet as a region of smooth terrain on the order of ~10 m in width. We assume that each element of the active area is emitting gas molecules with the same spatial distribution function, and integrate over the active area in order to calculate the gas drag force due to the vent. We consider two angular emission profiles (isotropic and lambertian), and assume plane-strain geometry. The vent surfaces were modeled at various angles with respect to the gravitational potential. To approximate scarps, we modeled a non-venting region located above the vent and at the same angle as the vent. The size of this non-venting region was allowed to vary. We assumed that the scarp face, which is composed of the vent and non-venting regions, eroded uniformly. Particles of a constant size are placed randomly on the surface of the vent, and their positions in time

Experimental Characterization of the Jet Wiping Process

NASA Astrophysics Data System (ADS)

Mendez, Miguel Alfonso; Enache, Adriana; Gosset, Anne; Buchlin, Jean-Marie

2018-06-01

This paper presents an experimental characterization of the jet wiping process, used in continuous coating applications to control the thickness of a liquid coat using an impinging gas jet. Time Resolved Particle Image Velocimetry (TR-PIV) is used to characterize the impinging gas flow, while an automatic interface detection algorithm is developed to track the liquid interface at the impact. The study of the flow interaction is combined with time resolved 3D thickness measurements of the liquid film remaining after the wiping, via Time Resolved Light Absorption (TR-LAbs). The simultaneous frequency analysis of liquid and gas flows allows to correlate their respective instability, provide an experimental data set for the validation of numerical studies and allows for formulating a working hypothesis on the origin of the coat non-uniformity encountered in many jet wiping processes.

Coupling of jet and accretion activity in the active galaxy NGC 1052

NASA Astrophysics Data System (ADS)

Boeck, Moritz; Kadler, Matthias; Ros, Eduardo; Weaver, Kimberly; Wilms, Joern; Brenneman, Laura; Angelakis, Emmanouil

The radio loud galaxy NGC 1052 has been monitored for the past fifteen years with Very Long Baseline Interferometry (VLBI) observations and has been the target of an intense multiwave-length monitoring campaign since 2005. This provides an excellent dataset for analyzing the relationship between properties of the relativistic jet and the accretion disk in active galactic nuclei. Components in the jet are tracked and the ejection times of new components are deter-mined. The analysis of the radio variability is complemented by the study of X-ray observations allowing us to draw conclusions on the accretion activity. The X-ray variability on weekly and monthly time scales is monitored with the Rossi X-ray Timing Explorer, whereas deep XMM-Newton and Suzaku observations provide spectra showing a broad Fe Kα line, whose variability can provide a particularly valuable probe of the inner accretion flow.

Electron collection enhancement arising from neutral gas jets on a charged vehicle in the ionosphere

NASA Technical Reports Server (NTRS)

Gilchrist, Brian E.; Banks, Peter M.; Neubert, Torsten; Williamson, P. Roger; Myers, Neil B.

1990-01-01

Observations of current collection enhancements due to cold nitrogen gas control jet emissions from a highly charged, isolated rocket payload in the ionosphere have been made during the cooperative high altitude rocket gun experiment (CHARGE) 2 using an electrically tethered mother/daughter payload system. The current collection enhancement was observed on a platform (daughter payload) located 100 to 400 m away from the main payload firing an energetic electron beam (mother payload). These results are interpreted in terms of an electrical discharge forming in close proximity to the daughter vehicle during the short periods of gas emission. The results indicate that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an otherwise undisturbed space plasma. The results are also compared with recent laboratory observations of hollow cathode plasma contactors operating in the 'ignited' mode.

Probing jets from young embedded sources

NASA Astrophysics Data System (ADS)

Nisini, Brunella

2017-08-01

Jets are intimately related to the process of star formation and disc accretion. Our present knowledge of this key ingredient in protostars mostly relies on observations of optical jets from T Tauri stars, where the original circumstellar envelope has been already cleared out. However, to understand how jets are originally formed and how their properties evolve with time, detailed observations of young accreting protostars, i.e. the class 0/I sources, are mandatory. The study of class0/I jets will be revolutionised by JWST, able to penetrate protostars dusty envelopes with unprecedented sensitivity and resolution. However, complementary information on parameters inferred from lines in different excitation regimes, for at least a representative sample of a few bright sources, is essential for a correct interpretation of the JWST results. Here we propose to observe four prototype bright jets from class0/I sources with the WFC3 in narrow band filters in order to acquire high angular resolution images in the [OI]6300A, [FeII]1.25 and [FeII]1.64um lines. These images will be used to: 1) provide accurate extinction maps of the jets that will be an important archival reference for any future observation on these jets. 2) measure key parameters as the mass flux, the iron abundance and the jet collimation on the hot gas component of the jets. These information will provide an invaluable reference frame for a comparison with similar parameters measured by JWST in a different gas regime. In addition, these observations will allow us to confront the properties of class 0/I jets with those of the more evolved T Tauri stars.

A pulsed supersonic gas jet target for precision spectroscopy at the HITRAP facility at GSI

NASA Astrophysics Data System (ADS)

Tiedemann, D.; Stiebing, K. E.; Winters, D. F. A.; Quint, W.; Varentsov, V.; Warczak, A.; Malarz, A.; Stöhlker, Th.

2014-11-01

A pulsed supersonic gas jet target for experiments at the HITRAP facility at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt has been designed and built as a multi-purpose installation for key experiments on fundamental atomic physics in strong fields. This setup is currently installed at the Institut für Kernphysik of Goethe-University, Frankfurt am Main (IKF), in order to explore its operation prior to its installation at the HITRAP facility. Design and performance of the target are described. The measured target densities of 5.9×1012 atoms/cm3 for helium and 8.1×1012 atoms/cm³ for argon at the stagnation pressure of 30 bar match the required values. The target-beam diameter of 0.9 mm and the pulsed operation mode (jet built-up-time ≤15 ms) are well suited for the use at HITRAP.

Physics-based Scaling Laws for Confined and Unconfined Transverse Jets

DTIC Science & Technology

2015-02-01

11(c). Once again, the jet is injected at 90 clockwise from the vertical axis . For the top row, with K increasing from left to right, the location...with previous data collected for gas turbine geometries (Holdeman 1993). It is apparent that the local optimum observed for six jets involves jet...behavior changed dramatically, with the emergence of a local optimum mixing state that is consistent with previous data collected for gas turbine

AGN jet-driven stochastic cold accretion in cluster cores

NASA Astrophysics Data System (ADS)

Prasad, Deovrat; Sharma, Prateek; Babul, Arif

2017-10-01

Several arguments suggest that stochastic condensation of cold gas and its accretion on to the central supermassive black hole (SMBH) is essential for active galactic nuclei (AGNs) feedback to work in the most massive galaxies that lie at the centres of galaxy clusters. Our 3-D hydrodynamic AGN jet-ICM (intracluster medium) simulations, looking at the detailed angular momentum distribution of cold gas and its time variability for the first time, show that the angular momentum of the cold gas crossing ≲1 kpc is essentially isotropic. With almost equal mass in clockwise and counterclockwise orientations, we expect a cancellation of the angular momentum on roughly the dynamical time. This means that a compact accretion flow with a short viscous time ought to form, through which enough accretion power can be channeled into jet mechanical energy sufficiently quickly to prevent a cooling flow. The inherent stochasticity, expected in feedback cycles driven by cold gas condensation, gives rise to a large variation in the cold gas mass at the centres of galaxy clusters, for similar cluster and SMBH masses, in agreement with the observations. Such correlations are expected to be much tighter for the smoother hot/Bondi accretion. The weak correlation between cavity power and Bondi power obtained from our simulations also matches observations.

Experimental study of elliptical jet from sub to supercritical conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muthukumaran, C. K.; Vaidyanathan, Aravind, E-mail: aravind7@iist.ac.in

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 weremore » 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.« less

Feedback by AGN Jets and Wide-angle Winds on a Galactic Scale

NASA Astrophysics Data System (ADS)

Dugan, Zachary; Gaibler, Volker; Silk, Joseph

2017-07-01

To investigate the differences in mechanical feedback from radio-loud and radio-quiet active galactic nuclei on the host galaxy, we perform 3D AMR hydrodynamic simulations of wide-angle, radio-quiet winds with different inclinations on a single, massive, gas-rich disk galaxy at a redshift of 2-3. We compare our results to hydrodynamic simulations of the same galaxy but with a jet. The jet has an inclination of 0° (perpendicular to the galactic plane), and the winds have inclinations of 0°, 45°, and 90°. We analyze the impact on the host’s gas, star formation, and circumgalactic medium. We find that jet feedback is energy-driven and wind feedback is momentum-driven. In all the simulations, the jet or wind creates a cavity mostly devoid of dense gas in the nuclear region where star formation is then quenched, but we find strong positive feedback in all the simulations at radii greater than 3 kpc. All four simulations have similar SFRs and stellar velocities with large radial and vertical components. However, the wind at an inclination of 90° creates the highest density regions through ram pressure and generates the highest rates of star formation due to its ongoing strong interaction with the dense gas of the galactic plane. With increased wind inclination, we find greater asymmetry in gas distribution and resulting star formation. Our model generates an expanding ring of triggered star formation with typical velocities of the order of 1/3 of the circular velocity, superimposed on the older stellar population. This should result in a potentially detectable blue asymmetry in stellar absorption features at kiloparsec scales.

Effects of Buoyancy on Laminar, Transitional, and Turbulent Gas Jet Diffusion Flames

NASA Technical Reports Server (NTRS)

Bahadori, M. Yousef; Stocker, Dennis P.; Vaughan, David F.; Zhou, Liming; Edelman, Raymond B.

1993-01-01

Gas jet diffusion flames have been a subject of research for many years. However, a better understanding of the physical and chemical phenomena occurring in these flames is still needed, and, while the effects of gravity on the burning process have been observed, the basic mechanisms responsible for these changes have yet to be determined. The fundamental mechanisms that control the combustion process are in general coupled and quite complicated. These include mixing, radiation, kinetics, soot formation and disposition, inertia, diffusion, and viscous effects. In order to understand the mechanisms controlling a fire, laboratory-scale laminar and turbulent gas-jet diffusion flames have been extensively studied, which have provided important information in relation to the physico-chemical processes occurring in flames. However, turbulent flames are not fully understood and their understanding requires more fundamental studies of laminar diffusion flames in which the interplay of transport phenomena and chemical kinetics is more tractable. But even this basic, relatively simple flame is not completely characterized in relation to soot formation, radiation, diffusion, and kinetics. Therefore, gaining an understanding of laminar flames is essential to the understanding of turbulent flames, and particularly fires, in which the same basic phenomena occur. In order to improve and verify the theoretical models essential to the interpretation of data, the complexity and degree of coupling of the controlling mechanisms must be reduced. If gravity is isolated, the complication of buoyancy-induced convection would be removed from the problem. In addition, buoyant convection in normal gravity masks the effects of other controlling parameters on the flame. Therefore, the combination of normal-gravity and microgravity data would provide the information, both theoretical and experimental, to improve our understanding of diffusion flames in general, and the effects of gravity on the

Silicon etching of difluoromethane atmospheric pressure plasma jet combined with its spectroscopic analysis

NASA Astrophysics Data System (ADS)

Sung, Yu-Ching; Wei, Ta-Chin; Liu, You-Chia; Huang, Chun

2018-06-01

A capacitivly coupled radio-frequency double-pipe atmospheric-pressure plasma jet is used for etching. An argon carrier gas is supplied to the plasma discharge jet; and CH2F2 etch gas is inserted into the plasma discharge jet, near the silicon substrate. Silicon etchings rate can be efficiently-controlled by adjusting the feeding etching gas composition and plasma jet operating parameters. The features of silicon etched by the plasma discharge jet are discussed in order to spatially spreading plasma species. Electronic excitation temperature and electron density are detected by increasing plasma power. The etched silicon profile exhibited an anisotropic shape and the etching rate was maximum at the total gas flow rate of 4500 sccm and CH2F2 concentration of 11.1%. An etching rate of 17 µm/min was obtained at a plasma power of 100 W.

Flight and Preflight Tests of a Ram Jet Burning Magnesium Slurry Fuel and Utilizing a Solid-propellant Gas Generator for Fuel Expulsion

NASA Technical Reports Server (NTRS)

Bartlett, Walter, A , jr; Hagginbotham, William K , Jr

1955-01-01

Data obtained from the first flight test of a ram jet utilizing a magnesium slurry fuel are presented. The ram jet accelerated from a Mach number of 1.75 to a Mach number of 3.48 in 15.5 seconds. During this period a maximum values of air specific impulse and gross thrust coefficient were calculated to be 151 seconds and 0.658, respectively. The rocket gas generator used as a fuel-pumping system operated successfully.

Influence of Xe and Kr impurities on x-ray yield from debris-free plasma x-ray sources with an Ar supersonic gas jet irradiated by femtosecond near-infrared-wavelength laser pulses

NASA Astrophysics Data System (ADS)

Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Petrov, G. M.; Safronova, A. S.; Petkov, E. E.; Moschella, J. J.; Shrestha, I.; Cline, W.; Wiewior, P.; Chalyy, O.

2016-11-01

Many aspects of physical phenomena occurring when an intense laser pulse with subpicosecond duration and an intensity of 1018-1019W /cm2 heats an underdense plasma in a supersonic clustered gas jet are studied to determine the relative contribution of thermal and nonthermal processes to soft- and hard-x-ray emission from debris-free plasmas. Experiments were performed at the University of Nevada, Reno (UNR) Leopard laser operated with a 15-J, 350-fs pulse and different pulse contrasts (107 or 105). The supersonic linear (elongated) nozzle generated Xe cluster-monomer gas jets as well as jets with Kr-Ar or Xe-Kr-Ar mixtures with densities of 1018-1019cm-3 . Prior to laser heating experiments, all jets were probed with optical interferometry and Rayleigh scattering to measure jet density and cluster distribution parameters. The supersonic linear jet provides the capability to study the anisotropy of x-ray yield from laser plasma and also laser beam self-focusing in plasma, which leads to efficient x-ray generation. Plasma diagnostics included x-ray diodes, pinhole cameras, and spectrometers. Jet signatures of x-ray emission from pure Xe gas, as well as from a mixture with Ar and Kr, was found to be very different. The most intense x-ray emission in the 1-9 KeV spectral region was observed from gas mixtures rather than pure Xe. Also, this x-ray emission was strongly anisotropic with respect to the direction of laser beam polarization. Non-local thermodynamic equilibrium (Non-LTE) models have been implemented to analyze the x-ray spectra to determine the plasma temperature and election density. Evidence of electron beam generation in the supersonic jet plasma was found. The influence of the subpicosecond laser pulse contrast (a ratio between the laser peak intensity and pedestal pulse intensity) on the jets' x-ray emission characteristics is discussed. Surprisingly, it was found that the x-ray yield was not sensitive to the prepulse contrast ratio.

Influence of jet-cooking corn bran on its antioxidant activities, phenolic contents and viscoelastic properties

USDA-ARS?s Scientific Manuscript database

Corn bran was subjected to high-shear and jet-cooking with or without alkaline treatment. The highest antioxidant activity was found in the soluble solids from jet-cooked corn bran without alkaline treatment. Jet-cooking under alkaline conditions resulted in a soluble fraction having the highest phe...

Twisting solar coronal jet launched at the boundary of an active region

NASA Astrophysics Data System (ADS)

Schmieder, B.; Guo, Y.; Moreno-Insertis, F.; Aulanier, G.; Yelles Chaouche, L.; Nishizuka, N.; Harra, L. K.; Thalmann, J. K.; Vargas Dominguez, S.; Liu, Y.

2013-11-01

Aims: A broad jet was observed in a weak magnetic field area at the edge of active region NOAA 11106 that also produced other nearby recurring and narrow jets. The peculiar shape and magnetic environment of the broad jet raised the question of whether it was created by the same physical processes of previously studied jets with reconnection occurring high in the corona. Methods: We carried out a multi-wavelength analysis using the EUV images from the Atmospheric Imaging Assembly (AIA) and magnetic fields from the Helioseismic and Magnetic Imager (HMI) both on-board the Solar Dynamics Observatory, which we coupled to a high-resolution, nonlinear force-free field extrapolation. Local correlation tracking was used to identify the photospheric motions that triggered the jet, and time-slices were extracted along and across the jet to unveil its complex nature. A topological analysis of the extrapolated field was performed and was related to the observed features. Results: The jet consisted of many different threads that expanded in around 10 minutes to about 100 Mm in length, with the bright features in later threads moving faster than in the early ones, reaching a maximum speed of about 200 km s-1. Time-slice analysis revealed a striped pattern of dark and bright strands propagating along the jet, along with apparent damped oscillations across the jet. This is suggestive of a (un)twisting motion in the jet, possibly an Alfvén wave. Bald patches in field lines, low-altitude flux ropes, diverging flow patterns, and a null point were identified at the basis of the jet. Conclusions: Unlike classical λ or Eiffel-tower-shaped jets that appear to be caused by reconnection in current sheets containing null points, reconnection in regions containing bald patches seems to be crucial in triggering the present jet. There is no observational evidence that the flux ropes detected in the topological analysis were actually being ejected themselves, as occurs in the violent phase of

The jet-ISM interactions in IC 5063

NASA Astrophysics Data System (ADS)

Mukherjee, Dipanjan; Wagner, Alexander Y.; Bicknell, Geoffrey V.; Morganti, Raffaella; Oosterloo, Tom; Nesvadba, Nicole; Sutherland, Ralph S.

2018-05-01

The interstellar medium of the radio galaxy IC 5063 is highly perturbed by an AGN jet expanding in the gaseous disc of the galaxy. We model this interaction with relativistic hydrodynamic simulations and multiphase initial conditions for the interstellar medium and compare the results with recent observations. As the jets flood through the intercloud channels of the disc, they ablate, accelerate, and disperse clouds to velocities exceeding 400 km s-1. Clouds are also destroyed or displaced in bulk from the central regions of the galaxy. Our models with jet powers of 1044 and 1045 erg s-1 are capable of reproducing many of the observed features in the position velocity diagram of IC 5063, and confirm the notion that the jet is responsible for the strongly perturbed gas dynamics seen in the ionized, neutral, and molecular gas phases. In our simulations, we also see strong venting of the jet plasma perpendicular to the disc, which entrains clumps and diffuse filaments into the halo of the galaxy. Our simulations are the first 3D hydrodynamic simulations of the jet and interstellar matter of IC 5063.

Life cycle assessment of residual lignocellulosic biomass-based jet fuel with activated carbon and lignosulfonate as co-products.

PubMed

Pierobon, Francesca; Eastin, Ivan L; Ganguly, Indroneil

2018-01-01

Bio-jet fuels are emerging as a valuable alternative to petroleum-based fuels for their potential for reducing greenhouse gas emissions and fossil fuel dependence. In this study, residual woody biomass from slash piles in the U.S. Pacific Northwest is used as a feedstock to produce iso-paraffinic kerosene, through the production of sugar and subsequent patented proprietary fermentation and upgrading. To enhance the economic viability and reduce the environmental impacts of iso-paraffinic kerosene, two co-products, activated carbon and lignosulfonate, are simultaneously produced within the same bio-refinery. A cradle-to-grave life cycle assessment (LCA) is performed for the residual woody biomass-based bio-jet fuel and compared against the cradle-to-grave LCA of petroleum-based jet fuel. This paper also discusses the differences in the environmental impacts of the residual biomass-based bio-jet fuel using two different approaches, mass allocation and system expansion, to partition the impacts between the bio-fuel and the co-products, which are produced in the bio-refinery. The environmental assessment of biomass-based bio-jet fuel reveals an improvement along most critical environmental criteria, as compared to its petroleum-based counterpart. However, the results present significant differences in the environmental impact of biomass-based bio-jet fuel, based on the partitioning method adopted. The mass allocation approach shows a greater improvement along most of the environmental criteria, as compared to the system expansion approach. However, independent of the partitioning approach, the results of this study reveal that more than the EISA mandated 60% reduction in the global warming potential could be achieved by substituting petroleum-based jet fuel with residual woody biomass-based jet fuel. Converting residual woody biomass from slash piles into bio-jet fuel presents the additional benefit of avoiding the impacts of slash pile burning in the forest, which

Active Control of High-Speed Free Jets Using High-Frequency Excitation

NASA Astrophysics Data System (ADS)

Upadhyay, Puja

Control of aerodynamic noise generated by high-performance jet engines continues to remain a serious problem for the aviation community. Intense low frequency noise produced by large-scale coherent structures is known to dominate acoustic radiation in the aft angles. A tremendous amount of research effort has been dedicated towards the investigation of many passive and active flow control strategies to attenuate jet noise, while keeping performance penalties to a minimum. Unsteady excitation, an active control technique, seeks to modify acoustic sources in the jet by leveraging the naturally-occurring flow instabilities in the shear layer. While excitation at a lower range of frequencies that scale with the dynamics of large-scale structures, has been attempted by a number of studies, effects at higher excitation frequencies remain severely unexplored. One of the major limitations stems from the lack of appropriate flow control devices that have sufficient dynamic response and/or control authority to be useful in turbulent flows, especially at higher speeds. To this end, the current study seeks to fulfill two main objectives. First, the design and characterization of two high-frequency fluidic actuators (25 and 60 kHz) are undertaken, where the target frequencies are guided by the dynamics of high-speed free jets. Second, the influence of high-frequency forcing on the aeroacoustics of high-speed jets is explored in some detail by implementing the nominally 25 kHz actuator on a Mach 0.9 (Re D = 5 x 105) free jet flow field. Subsequently, these findings are directly compared to the results of steady microjet injection experiments performed in the same rig and to prior jet noise control studies, where available. Finally, limited acoustic measurements were also performed by implementing the nominally 25 kHz actuators on jets at higher Mach numbers, including shock containing jets, and elevated temperatures. Using lumped element modeling as an initial guide, the current

The energetics of relativistic jets in active galactic nuclei with various kinetic powers

NASA Astrophysics Data System (ADS)

Musoke, Gibwa Rebecca; Young, Andrew; Molnar, Sandor; Birkinshaw, Mark

2018-01-01

Numerical simulations are an important tool in understanding the physical processes behind relativistic jets in active galactic nuclei. In such simulations different combinations of intrinsic jet parameters can be used to obtain the same jet kinetic powers. We present a numerical investigation of the effects of varying the jet power on the dynamic and energetic characteristics of the jets for two kinetic power regimes; in the first regime we change the jet density whilst maintaining a fixed velocity, in the second the jet density is held constant while the velocity is varied. We conduct 2D axisymmetric hydrodynamic simulations of bipolar jets propagating through an isothermal cluster atmosphere using the FLASH MHD code in pure hydrodynamics mode. The jets are simulated with kinetic powers ranging between 1045 and 1046 erg/s and internal Mach numbers ranging from 5.6 to 21.5.As the jets begin to propagate into the intracluster medium (ICM), the injected jet energy is converted into the thermal, kinetic and gravitational potential energy components of the jet cocoon and ICM. We explore the temporal evolution of the partitioning of the injected jet energy into the cocoon and the ICM and quantify the importance of entrainment process on the energy partitioning. We investigate the fraction of injected energy transferred to the thermal energy component of the jet-ICM system in the context of heating the cluster environments, noting that the jets simulated display peak thermalisation efficiencies of least 65% and a marked dependence on the jet density. We compare the efficiencies of the energy partitioning between the cocoon and ICM for the two kinetic power regimes and discuss the resulting efficiency-power scaling relations of each regime.

Extreme events in a vortex gas simulation of a turbulent half-jet

NASA Astrophysics Data System (ADS)

Suryanarayanan, Saikishan; Pathikonda, Gokul; Narasimha, Roddam

2012-11-01

Extensive simulations [arXiv:1008.2876v1 [physics.flu-dyn], BAPS.2010.DFD.LE.4] have shown that the temporally evolving vortex gas mixing layer has 3 regimes, including one which has a universal spreading rate. The present study explores the development of spatially evolving mixing layers, using a vortex gas model based on Basu et al. (1995 Appl. Math. Modelling). The effects of the velocity ratio (r) are analyzed via the most extensive simulations of this kind till date, involving up to 10000 vortices and averaging over up to 1000 convective times. While the temporal limit is approached as r approaches unity, striking features such as extreme events involving coherent structures, bending, deviation of the convection velocity from mean velocity, spatial feedback and greater sensitivity to downstream and free stream boundary conditions are observed in the half-jet (r = 0) limit. A detailed statistical analysis reveals possible causes for the large scatter across experiments, as opposed to the commonly adopted explanation of asymptotic dependence on initial conditions. Supported in part by contract no. Intel/RN/4288.

Radiatively-driven general relativistic jets

NASA Astrophysics Data System (ADS)

Vyas, Mukesh K.; Chattopadhyay, Indranil

2018-02-01

We use moment formalism of relativistic radiation hydrodynamics to obtain equations of motion of radial jets and solve them using polytropic equation of state of the relativistic gas. We consider curved space-time around black holes and obtain jets with moderately relativistic terminal speeds. In addition, the radiation field from the accretion disc, is able to induce internal shocks in the jet close to the horizon. Under combined effect of thermal as well as radiative driving, terminal speeds up to 0.75 (units of light speed) are obtained.

The influence of cavitation in the breakup of liquid free jets

NASA Astrophysics Data System (ADS)

Bode, Juergen

1991-03-01

The interaction between a diesel injection nozzle flow and the atomizing jet was investigated over a wide range of Reynolds numbers. If the pressure gradient towards the centerline of the injection nozzle, generated by the curved streamlines, becomes too large, cavitation occurs at the inlet corner. The cavitation region grows in length and boundary surface with increasing Reynolds number. The instability of the reentry flow causes unsteady fluctuations of the cavitation which influences the breakup of the liquid jet, whereby liquid films are generated which take off from the jet. Cavitation amplifies the mechanism of the atomization, based on the interaction between the jet and surrounding gas. The influence of the cavitation on the atomization is restricted to the region directly behind the nozzle exit. The injection pressure and the temperature of the gas hardly affect the atomization. The jet angle depends mainly on the density of the surrounding gas.

Numerical Study of AGN Jet Propagation with Two Dimensional Relativistic Hydrodynamic Code

NASA Astrophysics Data System (ADS)

Mizuta, Akira; Yamada, Shoichi; Takabe, Hideaki

2001-12-01

We investigate the morphology of Active Galactic Nuclei(AGN) jets. AGN jets propagate over kpc ~ Mpc and their beam velocities are close to the speed of light. The reason why many jets propagate over so long a distance and sustain a very collimated structure is not well understood. It is argued taht some dimensionless parameters, the density and the pressure ratio of the jet beam and the ambient gas, the Mach number of the beam, and relative speed of the beam compared to the speed of light, are very useful to understand the morphology of jets namely, bow shocks, cocoons, nodes etc. The role of each parameters has been studied by numerical simulations. But more research is necessary to understand it systematically. We have developed 2D relativistic hydrodynamic code to analyze relativistic jets. We pay attention to the propagation velocity which is derived from 1D momentum balance in the frame of the working surface. We show some of our models and discuss the dependence of the morphology of jets on the parameter.

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

Jet array impingement flow distributions and heat transfer characteristics. Effects of initial crossflow and nonuniform array geometry. [gas turbine engine component cooling

NASA Technical Reports Server (NTRS)

Florschuetz, L. W.; Metzger, D. E.; Su, C. C.; Isoda, Y.; Tseng, H. H.

1982-01-01

Two-dimensional arrays of circular air jets impinging on a heat transfer surface parallel to the jet orifice plate are considered. The jet flow, after impingement, is constrained to exit in a single direction along the channel formed by the jet orifice plate and the heat transfer surface. The configurations considered are intended to model those of interest in current and contemplated gas turbine airfoil midchord cooling applications. The effects of an initial crossflow which approaches the array through an upstream extension of the channel are considered. Flow distributions as well as heat transfer coefficients and adiabatic wall temperatures resolved to one streamwise hole spacing were measured as a function of the initial crossflow rate and temperature relative to the jet flow rate and temperature. Both Nusselt number profiles and dimensionless adiabatic wall temperature (effectiveness) profiles are presented and discussed. Special test results which show a significant reduction of jet orifice discharge coefficients owing to the effect of a confined crossflow are also presented, along with a flow distribution model which incorporates those effects. A nonuniform array flow distribution model is developed and validated.

Active Noise Control of Radiated Noise from Jets Originating NASA

NASA Technical Reports Server (NTRS)

Doty, Michael J.; Fuller, Christopher R.; Schiller, Noah H.; Turner, Travis L.

2013-01-01

The reduction of jet noise using a closed-loop active noise control system with highbandwidth active chevrons was investigated. The high frequency energy introduced by piezoelectrically-driven chevrons was demonstrated to achieve a broadband reduction of jet noise, presumably due to the suppression of large-scale turbulence. For a nozzle with one active chevron, benefits of up to 0.8 dB overall sound pressure level (OASPL) were observed compared to a static chevron nozzle near the maximum noise emission angle, and benefits of up to 1.9 dB OASPL were observed compared to a baseline nozzle with no chevrons. The closed-loop actuation system was able to effectively reduce noise at select frequencies by 1-3 dB. However, integrated OASPL did not indicate further reduction beyond the open-loop benefits, most likely due to the preliminary controller design, which was focused on narrowband performance.

Efficiency of SparkJet

NASA Technical Reports Server (NTRS)

Golbabaei-Asl, M.; Knight, D.; Wilkinson, S.

2013-01-01

The thermal efficiency of a SparkJet is evaluated by measuring the impulse response of a pendulum subject to a single spark discharge. The SparkJet is attached to the end of a pendulum. A laser displacement sensor is used to measure the displacement of the pendulum upon discharge. The pendulum motion is a function of the fraction of the discharge energy that is channeled into the heating of the gas (i.e., increasing the translational-rotational temperature). A theoretical perfect gas model is used to estimate the portion of the energy from the heated gas that results in equivalent pendulum displacement as in the experiment. The earlier results from multiple runs for different capacitances of C = 3, 5, 10, 20, and 40(micro)F demonstrate that the thermal efficiency decreases with higher capacitive discharges.1 In the current paper, results from additional run cases have been included and confirm the previous results

Detection of helicoidal motion in the optical jet of PKS 0521-365

NASA Astrophysics Data System (ADS)

Jiménez-Andrade, E. F.; Chavushyan, V.; León-Tavares, J.; Patiño-Álvarez, V. M.; Olguín-Iglesias, A.; Kotilainen, J.; Falomo, R.; Hyvönen, T.

2017-09-01

The jet activity of active galactic nuclei (AGNs), and its interaction with the interstellar medium, may play a pivotal role in the processes that regulate the growth and star formation of its host galaxy. Observational evidence that pinpoints the conditions of such interaction is paramount to unveil the physical processes involved. We report on the discovery of extended emission-line regions exhibiting an S-shaped morphology along the optical jet of the radio-loud AGN PKS 0521-365 (z = 0.055), by using long-slit spectroscopic observations obtained with FOcal Reducer/low dispersion Spectrograph 2 on the Very Large Telescope. The velocity pattern derived from the [O II] λ3727 Å, H β λ4861 Å and [O III] λλ4959, 5007 Å emission lines is well fitted by a sinusoidal function of the form: v(r) = αr1/2sin(βr1/2 + γ), suggesting helicoidal motions along the jet up to distances of 20 kpc. We estimate a lower limit for the mass of the outflowing ionized gas along the jet of ˜104 M⊙. Helical magnetic fields and jet precession have been proposed to explain helicoidal paths along the jet at pc scales; nevertheless, it is not clear yet whether these hypotheses may hold at kpc scales.

Feedback by AGN Jets and Wide-angle Winds on a Galactic Scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dugan, Zachary; Silk, Joseph; Gaibler, Volker

To investigate the differences in mechanical feedback from radio-loud and radio-quiet active galactic nuclei on the host galaxy, we perform 3D AMR hydrodynamic simulations of wide-angle, radio-quiet winds with different inclinations on a single, massive, gas-rich disk galaxy at a redshift of 2–3. We compare our results to hydrodynamic simulations of the same galaxy but with a jet. The jet has an inclination of 0° (perpendicular to the galactic plane), and the winds have inclinations of 0°, 45°, and 90°. We analyze the impact on the host’s gas, star formation, and circumgalactic medium. We find that jet feedback is energy-drivenmore » and wind feedback is momentum-driven. In all the simulations, the jet or wind creates a cavity mostly devoid of dense gas in the nuclear region where star formation is then quenched, but we find strong positive feedback in all the simulations at radii greater than 3 kpc. All four simulations have similar SFRs and stellar velocities with large radial and vertical components. However, the wind at an inclination of 90° creates the highest density regions through ram pressure and generates the highest rates of star formation due to its ongoing strong interaction with the dense gas of the galactic plane. With increased wind inclination, we find greater asymmetry in gas distribution and resulting star formation. Our model generates an expanding ring of triggered star formation with typical velocities of the order of 1/3 of the circular velocity, superimposed on the older stellar population. This should result in a potentially detectable blue asymmetry in stellar absorption features at kiloparsec scales.« less

Large area atmospheric-pressure plasma jet

DOEpatents

Selwyn, Gary S.; Henins, Ivars; Babayan, Steve E.; Hicks, Robert F.

2001-01-01

Large area atmospheric-pressure plasma jet. A plasma discharge that can be operated at atmospheric pressure and near room temperature using 13.56 MHz rf power is described. Unlike plasma torches, the discharge produces a gas-phase effluent no hotter than 250.degree. C. at an applied power of about 300 W, and shows distinct non-thermal characteristics. In the simplest design, two planar, parallel electrodes are employed to generate a plasma in the volume therebetween. A "jet" of long-lived metastable and reactive species that are capable of rapidly cleaning or etching metals and other materials is generated which extends up to 8 in. beyond the open end of the electrodes. Films and coatings may also be removed by these species. Arcing is prevented in the apparatus by using gas mixtures containing He, which limits ionization, by using high flow velocities, and by properly spacing the rf-powered electrode. Because of the atmospheric pressure operation, there is a negligible density of ions surviving for a sufficiently long distance beyond the active plasma discharge to bombard a workpiece, unlike the situation for low-pressure plasma sources and conventional plasma processing methods.

Numerical analysis on cooling performance of counterflowing jet over aerodisked blunt body

NASA Astrophysics Data System (ADS)

Barzegar Gerdroodbary, M.

2014-09-01

This study investigates a combined technique of both an active flow control concept that uses counterflowing jets and an aerodisk spike as a new method to significantly modify external flowfields and heat reduction in a hypersonic flow around a nose cone. The coolant gas (Carbon Dioxide and Helium) is chosen to inject from the tip of the nose cone to cool the recirculation region. The gases are considered to be ideal, and the computational domain is axisymmetric. The analysis shows that the counterflowing jet has significant effects on the flowfield and reduces the heat load over the nose cone. The Helium jet is found to have a relatively more effective cooling performance.

Laminar and turbulent flow modes of cold atmospheric pressure argon plasma jet

NASA Astrophysics Data System (ADS)

Basher, Abdulrahman H.; Mohamed, Abdel-Aleam H.

2018-05-01

Laminar and turbulent flow modes of a cold atmospheric pressure argon plasma jet are investigated in this work. The effects of the gas flow rate, applied voltage, and frequency on each plasma mode and on intermodal transitions are characterized using photographic, electrical, and spectroscopic techniques. Increasing the gas flow rate increases the plasma jet length in the laminar mode. Upon transition to the turbulent mode, increasing the gas flow rate leads to a decrease in the plasma jet length. The flow rate at which the jet transitions from laminar to turbulent increases with the applied voltage. The presence of nitric oxide (NO) radicals is indicated by the emission spectra of the turbulent plasmas only, while excited Ar, N2, OH, and O excited species are produced in both laminar and turbulent modes. With no distinctive behavior observed upon transition between the two operating modes, the power consumption was found to be insensitive to gas flow rate variation, while the energy density was found to decrease exponentially with the gas flow rate. Rotational and vibrational temperature measurements of the two plasma modes indicated that they are of the non-thermal equilibrium plasma type. Since they offer NO radicals while maintaining the benefits of the laminar plasma jet, the turbulent plasma jet is more useful than its laminar counterpart in biomedical applications.

Intrinsic physical conditions and structure of relativistic jets in active galactic nuclei

NASA Astrophysics Data System (ADS)

Nokhrina, E. E.; Beskin, V. S.; Kovalev, Y. Y.; Zheltoukhov, A. A.

2015-03-01

The analysis of the frequency dependence of the observed shift of the cores of relativistic jets in active galactic nuclei (AGNs) allows us to evaluate the number density of the outflowing plasma ne and, hence, the multiplicity parameter λ = ne/nGJ, where nGJ is the Goldreich-Julian number density. We have obtained the median value for λmed = 3 × 1013 and the median value for the Michel magnetization parameter σM, med = 8 from an analysis of 97 sources. Since the magnetization parameter can be interpreted as the maximum possible Lorentz factor Γ of the bulk motion which can be obtained for relativistic magnetohydrodynamic (MHD) flow, this estimate is in agreement with the observed superluminal motion of bright features in AGN jets. Moreover, knowing these key parameters, one can determine the transverse structure of the flow. We show that the poloidal magnetic field and particle number density are much larger in the centre of the jet than near the jet boundary. The MHD model can also explain the typical observed level of jet acceleration. Finally, casual connectivity of strongly collimated jets is discussed.

Battery-Powered RF Pre-Ionization System for the Caltech Magnetohydrodynamically-Driven Jet Experiment: RF Discharge Properties and MHD-Driven Jet Dynamics

NASA Astrophysics Data System (ADS)

Chaplin, Vernon H.

This thesis describes investigations of two classes of laboratory plasmas with rather different properties: partially ionized low pressure radiofrequency (RF) discharges, and fully ionized high density magnetohydrodynamically (MHD)-driven jets. An RF pre-ionization system was developed to enable neutral gas breakdown at lower pressures and create hotter, faster jets in the Caltech MHD-Driven Jet Experiment. The RF plasma source used a custom pulsed 3 kW 13.56 MHz RF power amplifier that was powered by AA batteries, allowing it to safely float at 4-6 kV with the cathode of the jet experiment. The argon RF discharge equilibrium and transport properties were analyzed, and novel jet dynamics were observed. Although the RF plasma source was conceived as a wave-heated helicon source, scaling measurements and numerical modeling showed that inductive coupling was the dominant energy input mechanism. A one-dimensional time-dependent fluid model was developed to quantitatively explain the expansion of the pre-ionized plasma into the jet experiment chamber. The plasma transitioned from an ionizing phase with depressed neutral emission to a recombining phase with enhanced emission during the course of the experiment, causing fast camera images to be a poor indicator of the density distribution. Under certain conditions, the total visible and infrared brightness and the downstream ion density both increased after the RF power was turned off. The time-dependent emission patterns were used for an indirect measurement of the neutral gas pressure. The low-mass jets formed with the aid of the pre-ionization system were extremely narrow and collimated near the electrodes, with peak density exceeding that of jets created without pre-ionization. The initial neutral gas distribution prior to plasma breakdown was found to be critical in determining the ultimate jet structure. The visible radius of the dense central jet column was several times narrower than the axial current channel

Supersonic Injection of Aerated Liquid Jet

NASA Astrophysics Data System (ADS)

Choudhari, Abhijit; Sallam, Khaled

2016-11-01

A computational study of the exit flow of an aerated two-dimensional jet from an under-expanded supersonic nozzle is presented. The liquid sheet is operating within the annular flow regime and the study is motivated by the application of supersonic nozzles in air-breathing propulsion systems, e.g. scramjet engines, ramjet engines and afterburners. The simulation was conducted using VOF model and SST k- ω turbulence model. The test conditions included: jet exit of 1 mm and mass flow rate of 1.8 kg/s. The results show that air reaches transonic condition at the injector exit due to the Fanno flow effects in the injector passage. The aerated liquid jet is alternately expanded by Prandtl-Meyer expansion fan and compressed by oblique shock waves due to the difference between the back (chamber) pressure and the flow pressure. The process then repeats itself and shock (Mach) diamonds are formed at downstream of injector exit similar to those typical of exhaust plumes of propulsion system. The present results, however, indicate that the flow field of supersonic aerated liquid jet is different from supersonic gas jets due to the effects of water evaporation from the liquid sheet. The contours of the Mach number, static pressure of both cases are compared to the theory of gas dynamics.

The effect of ethanol gas impurity on the discharge mode and discharge products of argon plasma jet at atmospheric pressure

NASA Astrophysics Data System (ADS)

Xia, Wenjie; Liu, Dingxin; Xu, Han; Wang, Xiaohua; Liu, Zhijie; Rong, Mingzhe; Kong, Michael G.

2018-05-01

Argon is a widely used working gas of plasmas, which is much cheaper than helium but on the other hand much more difficult to generate diffuse discharge at atmospheric pressure. In order to meet the application requirements, plenty of researches have been reported to facilitate the diffuse discharge happening for argon plasmas, and in this paper an approach of using ethanol gas (EtOH) impurity is investigated. The discharge characteristics of Ar + EtOH plasma jet are studied as a function of the applied voltage and the concentration of EtOH, from which the concentration of EtOH between ∼200 and ∼3300 parts per million (ppm) is determined necessary for the generation of diffuse discharge. Compared with the helium plasma jet in literature, it is deduced that the diffuse discharge is probably caused by the Penning ionization happening between the metastable argon and EtOH. The discharge products of Ar + EtOH (672 ppm) plasma jet are measured and the corresponding chemistry pathways are analyzed. About 20% of EtOH is decomposed via complex chemical reactions to form more than a dozen of neutral species, such as CH3CHO, CH3COOH, CO, H2O, and C n H2n+2 (n ≥ 3), and various kinds of ionic species, including C+, CH+, ArH+, {{{{O}}}2}-, CH3CH2O‑, etc.

High-Resolution X-Ray Imaging of Colliding Radio-Jet Galaxies

NASA Technical Reports Server (NTRS)

Born, Kirk D.; Whitmore, Brad

1996-01-01

We received ROSAT data for four program objects:3C31,3C278,3C449,and NGC1044. The first three sources were observed with the ROSAT HRI instrument. Our plan was to use the HRI to image the hot gas distribution in a few pairs of strongly disturbed interacting elliptical galaxies which are also strong radio sources having a bent-jet source morphology. The PSPC was used for NGC1044 in order to obtain a flux measurement to use in planning future High Resolution Imager (HRI) observations of that source. Though we never requested such HRI observations of NGC1044, others have used those archival PSPC data from our project for other research projects and analyses. The goal of the program was to elucidate the detailed distribution of hot gas into which the jets flow. The X-ray data were consequently analyzed in conjunction with existing VLA radio maps, optical broad-band and H-alpha Charge Couple device (CCD) images, and optical kinematic data to constrain models for the propagation of ballistic jets in interacting galaxies. We were able to test and validate the claimed causal connection between tidal interaction, the presence of gas, and the onset of activity in galaxies. The full multi-wavelength multi-observatory analyses described here are still on-going and will be published in the future. Because of the relevance of this research to on-going work in the field of active galaxies, the grant was used to support travel to several scientific meetings where our x-ray analysis, numerical modeling, and related radio results were presented and discussed.

Separation Of Liquid And Gas In Zero Gravity

NASA Technical Reports Server (NTRS)

Howard, Frank S.; Fraser, Wilson S.

1991-01-01

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

Exhaust turbine and jet propulsion systems

NASA Technical Reports Server (NTRS)

Leist, Karl; Knornschild, Eugen

1951-01-01

DVL experimental and analytical work on the cooling of turbine blades by using ram air as the working fluid over a sector or sectors of the turbine annulus area is summarized. The subsonic performance of ram-jet, turbo-jet, and turbine-propeller engines with both constant pressure and pulsating-flow combustion is investigated. Comparison is made with the performance of a reciprocating engine and the advantages of the gas turbine and jet-propulsion engines are analyzed. Nacelle installation methods and power-level control are discussed.

Deepest Image of Exploded Star Uncovers Bipolar Jets

NASA Technical Reports Server (NTRS)

2004-01-01

This spectacular Chandra X-Ray Observatory (CXO) image of the supernova remnant Cassiopeia A is the most detailed image ever made of the remains of an exploded star. The one-million-second image shows a bright outer ring (green) 10 light years in diameter that marks the location of a shock wave generated by the supernova explosion. In the upper left corner is a large jet-like structure that protrudes beyond the shock wave, and a counter-jet can be seen on the lower right. The x-ray spectra show that the jets are rich in silicon atoms, and relatively poor in iron atoms. This indicates that the jets formed soon after the initial explosion of the star, otherwise, the jets should have contained large quantities of iron from the star's central regions. The bright blue areas are composed almost purely of iron gas, which was produced in the central, hottest regions of the star and somehow ejected in a direction almost perpendicular to the jets. The bright source at the center of the image is presumed to be a neutron star created during the supernova. Unlike most others, this neutron star is quiet, faint, and so far shows no evidence of pulsed radiation. A working hypothesis is that the explosion that created Cassiopeia A produced high speed jets similar to, but less energetic than, the hyper nova jets thought to produce gamma-ray bursts. During the explosion, the star may have developed an extremely strong magnetic filed that helped to accelerate the jets and later stifled any pulsar wind activity. CXO project management is the responsibility of NASA's Marshall Space Flight Center in Huntsville, Alabama.

On the structure of pulsed plasma jets

NASA Astrophysics Data System (ADS)

Cavolowsky, John Arthur

A pulsed plasma jet is a turbulent, inhomogeneous fluid mechanical discharge capable of initiating and inhancing combustion. Having shown the ability to ignite lean fuel mixtures, is now offers the potential for real-time control of combustion processes. The fluid mechanical and chemical properties of such jets are explored. The fluid mechanical structure of the jet was examined using two optical diagnostic techniques. Self-light streak photography provided information on the motion of luminous gas particles in its core. The turbulent, thermal evolution of the jet was explored using high speed laser schlieren cinematography. By examine plasma jet generators with both opaque and transparent plasma cavities, detailed information on plasma formation and jet structure, beginning with the electric arc discharge in the cavity, was obtained. Molecular beam mass spectroscopy was used to determine temperature and species concentration in the jet. Both noncombustible and combustible jets were studied. Species measurements in combustible jets revealed significant concentrations of radicals and products of complete as well as incomplete combustion.

Dynamics and density distributions in a capillary-discharge waveguide with an embedded supersonic jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matlis, N. H., E-mail: nmatlis@gmail.com; Gonsalves, A. J.; Steinke, S.

We present an analysis of the gas dynamics and density distributions within a capillary-discharge waveguide with an embedded supersonic jet. This device provides a target for a laser plasma accelerator which uses longitudinal structuring of the gas-density profile to enable control of electron trapping and acceleration. The functionality of the device depends sensitively on the details of the density profile, which are determined by the interaction between the pulsed gas in the jet and the continuously-flowing gas in the capillary. These dynamics are captured by spatially resolving recombination light from several emission lines of the plasma as a function ofmore » the delay between the jet and the discharge. We provide a phenomenological description of the gas dynamics as well as a quantitative evaluation of the density evolution. In particular, we show that the pressure difference between the jet and the capillary defines three regimes of operation with qualitatively different longitudinal density profiles and show that jet timing provides a sensitive method for tuning between these regimes.« less

Jet-induced star formation in 3C 285 and Minkowski's Object

NASA Astrophysics Data System (ADS)

Salomé, Q.; Salomé, P.; Combes, F.

2015-02-01

How efficiently star formation proceeds in galaxies is still an open question. Recent studies suggest that active galactic nucleus (AGN) can regulate the gas accretion and thus slow down star formation (negative feedback). However, evidence of AGN positive feedback has also been observed in a few radio galaxies (e.g. Centaurus A, Minkowski's Object, 3C 285, and the higher redshift 4C 41.17). Here we present CO observations of 3C 285 and Minkowski's Object, which are examples of jet-induced star formation. A spot (named 3C 285/09.6 in the present paper) aligned with the 3C 285 radio jet at a projected distance of ~70 kpc from the galaxy centre shows star formation that is detected in optical emission. Minkowski's Object is located along the jet of NGC 541 and also shows star formation. Knowing the distribution of molecular gas along the jets is a way to study the physical processes at play in the AGN interaction with the intergalactic medium. We observed CO lines in 3C 285, NGC 541, 3C 285/09.6, and Minkowski's Object with the IRAM 30 m telescope. In the central galaxies, the spectra present a double-horn profile, typical of a rotation pattern, from which we are able to estimate the molecular gas density profile of the galaxy. The molecular gas appears to be in a compact reservoir, which could be evidence of an early phase of the gas accretion after a recent merger event in 3C 285. No kinematic signature of a molecular outflow is detected by the 30 m telescope. Interestingly, 3C 285/09.6 and Minkowski's Object are not detected in CO. The cold gas mass upper limits are consistent with a star formation induced by the compression of dense ambient material by the jet. The depletion time scales in 3C 285/09.6 and Minkowski's Object are of the order of and even shorter than what is found in 3C 285, NGC 541, and local spiral galaxies (109 yr). The upper limit of the molecular gas surface density in 3C 285/09.6 at least follows a Schmidt-Kennicutt law if the emitting region

The regimes of twin-fluid jet-in-crossflow at atmospheric and jet-engine operating conditions

NASA Astrophysics Data System (ADS)

Tan, Zu Puayen; Bibik, Oleksandr; Shcherbik, Dmitriy; Zinn, Ben T.; Patel, Nayan

2018-02-01

The "Twin-Fluid Jet-in-Crossflow (TF-JICF)" is a nascent variation of the classical JICF, in which a liquid jet is co-injected with an annular sleeve of gas into a gaseous crossflow. Jet-engine designers are interested in using TF-JICF for liquid-fuel injection and atomization in the next-generation combustors because it is expected to minimize combustor-damaging auto-ignition and fuel-coking tendencies. However, experimental data of TF-JICF are sparse. Furthermore, a widely accepted TF-JICF model that correlates the spray's penetration to the combined liquid-gas momentum-flux ratio (Jeff) is increasingly showing discrepancy with emerging results, suggesting a gap in the current understanding of TF-JICF. This paper describes an investigation that addressed the gap by experimentally characterizing the TF-JICF produced by a single injector across wide ranges of operating conditions (i.e., jet-A injectant, crossflow of air, crossflow Weber number = 175-1050, crossflow pressure Pcf = 1.8-9.5 atm, momentum-flux ratio J = 5-40, and air-nozzle dP = 0%-150% of Pcf). These covered the conditions previously used to develop the Jeff model, recently reported conditions that produced Jeff discrepancies, and high-pressure conditions found in jet-engines. Dye-based shadowgraph was used to acquire high-resolution (13.52 μm/pixel) images of the TF-JICF, which revealed wide-ranging characteristics such as the disrupted Rayleigh-Taylor jet instabilities, air-induced jet corrugations, spray-bifurcations, and prompt-atomization. Analyses of the data showed that contrary to the literature, the TF-JICF's penetration is not monotonically related to Jeff. A new conceptual framework for TF-JICF is proposed, where the flow configuration is composed of four regimes, each having different penetration trends, spray structures, and underlying mechanisms.

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.

Parsec-scale Faraday rotation and polarization of 20 active galactic nuclei jets

NASA Astrophysics Data System (ADS)

Kravchenko, E. V.; Kovalev, Y. Y.; Sokolovsky, K. V.

2017-05-01

We perform polarimetry analysis of 20 active galactic nuclei jets using the very long baseline array at 1.4, 1.6, 2.2, 2.4, 4.6, 5.0, 8.1, 8.4 and 15.4 GHz. The study allowed us to investigate linearly polarized properties of the jets at parsec scales: distribution of the Faraday rotation measure (RM) and fractional polarization along the jets, Faraday effects and structure of Faraday-corrected polarization images. Wavelength dependence of the fractional polarization and polarization angle is consistent with external Faraday rotation, while some sources show internal rotation. The RM changes along the jets, systematically increasing its value towards synchrotron self-absorbed cores at shorter wavelengths. The highest core RM reaches 16 900 rad m-2 in the source rest frame for the quasar 0952+179, suggesting the presence of highly magnetized, dense media in these regions. The typical RM of transparent jet regions has values of an order of a hundred rad m-2. Significant transverse RM gradients are observed in seven sources. The magnetic field in the Faraday screen has no preferred orientation, and is observed to be random or regular from source to source. Half of the sources show evidence for the helical magnetic fields in their rotating magneto-ionic media. At the same time jets themselves contain large-scale, ordered magnetic fields and tend to align its direction with the jet flow. The observed variety of polarized signatures can be explained by a model of spine-sheath jet structure.

HUBBLE VIEWS OF THREE STELLAR JETS

NASA Technical Reports Server (NTRS)

2002-01-01

These NASA Hubble Space Telescope views of gaseous jets from three newly forming stars show a new level of detail in the star formation process, and are helping to solve decade-old questions about the secrets of star birth. Jets are a common 'exhaust product' of the dynamics of star formation. They are blasted away from a disk of gas and dust falling onto an embryonic star. [upper left] - This view of a protostellar object called HH-30 reveals an edge-on disk of dust encircling a newly forming star. Light from the forming star illuminates the top and bottom surfaces of the disk, making them visible, while the star itself is hidden behind the densest parts of the disk. The reddish jet emanates from the inner region of the disk, and possibly directly from the star itself. Hubble's detailed view shows, for the first time, that the jet expands for several billion miles from the star, but then stays confined to a narrow beam. The protostar is 450 light-years away in the constellation Taurus. Credit: C. Burrows (STScI and ESA), the WFPC 2 Investigation Definition Team, and NASA [upper right] - This view of a different and more distant jet in object HH-34 shows a remarkable beaded structure. Once thought to be a hydrodynamic effect (similar to shock diamonds in a jet aircraft exhaust), this structure is actually produced by a machine-gun-like blast of 'bullets' of dense gas ejected from the star at speeds of one-half million miles per hour. This structure suggests the star goes through episodic 'fits' of construction where chunks of material fall onto the star from a surrounding disk. The protostar is 1,500 light- years away and in the vicinity of the Orion Nebula, a nearby star birth region. Credit: J. Hester (Arizona State University), the WFPC 2 Investigation Definition Team, and NASA [bottom] - This view of a three trillion mile-long jet called HH-47 reveals a very complicated jet pattern that indicates the star (hidden inside a dust cloud near the left edge of the

Production and correlation of reactive oxygen and nitrogen species in gas- and liquid-phase generated by helium plasma jets under different pulse widths

NASA Astrophysics Data System (ADS)

Liu, Zhijie; Zhou, Chunxi; Liu, Dingxin; Xu, Dehui; Xia, Wenjie; Cui, Qingjie; Wang, Bingchuan; Kong, Michael G.

2018-01-01

In this paper, we present the effects of the pulse width (PW) on the plasma jet's discharge characteristics, particularly focusing on the production and correlation of the reactive oxygen and nitrogen species (RONS) in gas- and liquid-phase. It is found that the length of plasma jet plume first increases before the PW of 10 μs, then gradually decreases and finally almost remains unchanged beyond 150 μs. The plasma bullet disappears after the falling edge of the voltage pulse at low PW, while it terminates far ahead of the falling edge of voltage pulse at high PW. This is mainly attributed to accumulation of space charges that lead to weakening of the reduced electric field with an increase of PW from low to high. More important, it is found that the excited reactive species, the positive and negative ions from plasma jet, and the concentrations of NO2- and NO3- in deionized water exposed to plasma jet also display the first increasing and then decreasing change trend with increase of PW, while the concentration of H2O2 in water almost displays the linearly increasing trend. This mainly results from the formation of the H3O+ and HO2-, as well as their ion water clusters that can produce more OH radicals to be converted into H2O2, while the NO2- and NO3- in gas phase can transport into water and exist most stably in water. The water cluster formation at gas-liquid interface is an important key process that can affect the chemical nature and dose of aqueous RONS in water; this is beneficial for understanding how the RONS are formed in liquid-phase.

Well-to-wake analysis of ethanol-to-jet and sugar-to-jet pathways

DOE PAGES

Han, Jeongwoo; Tao, Ling; Wang, Michael

2017-01-24

To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the aviation industry has paid increasing attention to bio-based alternative jet fuels (AJFs), which may provide lower life-cycle petroleum consumption and greenhouse gas (GHG) emissions than petroleum jet fuel. Here, this study presents well-to-wake (WTWa) results for four emerging AJFs: ethanol-to-jet (ETJ) from corn and corn stover, and sugar-to-jet (STJ) from corn stover via both biological and catalytic conversion. For the ETJ pathways, two plant designs were examined: integrated (processing corn or corn stover as feedstock) and distributed (processing ethanol as feedstock). Also, three H 2more » options for STJ via catalytic conversion are investigated: external H 2 from natural gas (NG) steam methane reforming (SMR), in situ H 2, and H 2 from biomass gasification. Results demonstrate that the feedstock is a key factor in the WTWa GHG emissions of ETJ: corn- and corn stover-based ETJ are estimated to produce WTWa GHG emissions that are 16 and 73%, respectively, less than those of petroleum jet. As for the STJ pathways, this study shows that STJ via biological conversion could generate WTWa GHG emissions 59% below those of petroleum jet. STJ via catalytic conversion could reduce the WTWa GHG emissions by 28% with H 2 from NG SMR or 71% with H 2 from biomass gasification than those of petroleum jet. This study also examines the impacts of co-product handling methods, and shows that the WTWa GHG emissions of corn stover-based ETJ, when estimated with a displacement method, are lower by 11 g CO 2e/MJ than those estimated with an energy allocation method. Corn- and corn stover-based ETJ as well as corn stover-based STJ show potentials to reduce WTWa GHG emissions compared to petroleum jet. Particularly, WTWa GHG emissions of STJ via catalytic conversion depend highly on the hydrogen source. On the other hand, ETJ offers unique opportunities to exploit extensive existing

Well-to-wake analysis of ethanol-to-jet and sugar-to-jet pathways.

PubMed

Han, Jeongwoo; Tao, Ling; Wang, Michael

2017-01-01

To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the aviation industry has paid increasing attention to bio-based alternative jet fuels (AJFs), which may provide lower life-cycle petroleum consumption and greenhouse gas (GHG) emissions than petroleum jet fuel. This study presents well-to-wake (WTWa) results for four emerging AJFs: ethanol-to-jet (ETJ) from corn and corn stover, and sugar-to-jet (STJ) from corn stover via both biological and catalytic conversion. For the ETJ pathways, two plant designs were examined: integrated (processing corn or corn stover as feedstock) and distributed (processing ethanol as feedstock). Also, three H 2 options for STJ via catalytic conversion are investigated: external H 2 from natural gas (NG) steam methane reforming (SMR), in situ H 2 , and H 2 from biomass gasification. Results demonstrate that the feedstock is a key factor in the WTWa GHG emissions of ETJ: corn- and corn stover-based ETJ are estimated to produce WTWa GHG emissions that are 16 and 73%, respectively, less than those of petroleum jet. As for the STJ pathways, this study shows that STJ via biological conversion could generate WTWa GHG emissions 59% below those of petroleum jet. STJ via catalytic conversion could reduce the WTWa GHG emissions by 28% with H 2 from NG SMR or 71% with H 2 from biomass gasification than those of petroleum jet. This study also examines the impacts of co-product handling methods, and shows that the WTWa GHG emissions of corn stover-based ETJ, when estimated with a displacement method, are lower by 11 g CO 2 e/MJ than those estimated with an energy allocation method. Corn- and corn stover-based ETJ as well as corn stover-based STJ show potentials to reduce WTWa GHG emissions compared to petroleum jet. Particularly, WTWa GHG emissions of STJ via catalytic conversion depend highly on the hydrogen source. On the other hand, ETJ offers unique opportunities to exploit extensive existing corn ethanol

Well-to-wake analysis of ethanol-to-jet and sugar-to-jet pathways

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Jeongwoo; Tao, Ling; Wang, Michael

To reduce the environmental impacts of the aviation sector as air traffic grows steadily, the aviation industry has paid increasing attention to bio-based alternative jet fuels (AJFs), which may provide lower life-cycle petroleum consumption and greenhouse gas (GHG) emissions than petroleum jet fuel. Here, this study presents well-to-wake (WTWa) results for four emerging AJFs: ethanol-to-jet (ETJ) from corn and corn stover, and sugar-to-jet (STJ) from corn stover via both biological and catalytic conversion. For the ETJ pathways, two plant designs were examined: integrated (processing corn or corn stover as feedstock) and distributed (processing ethanol as feedstock). Also, three H 2more » options for STJ via catalytic conversion are investigated: external H 2 from natural gas (NG) steam methane reforming (SMR), in situ H 2, and H 2 from biomass gasification. Results demonstrate that the feedstock is a key factor in the WTWa GHG emissions of ETJ: corn- and corn stover-based ETJ are estimated to produce WTWa GHG emissions that are 16 and 73%, respectively, less than those of petroleum jet. As for the STJ pathways, this study shows that STJ via biological conversion could generate WTWa GHG emissions 59% below those of petroleum jet. STJ via catalytic conversion could reduce the WTWa GHG emissions by 28% with H 2 from NG SMR or 71% with H 2 from biomass gasification than those of petroleum jet. This study also examines the impacts of co-product handling methods, and shows that the WTWa GHG emissions of corn stover-based ETJ, when estimated with a displacement method, are lower by 11 g CO 2e/MJ than those estimated with an energy allocation method. Corn- and corn stover-based ETJ as well as corn stover-based STJ show potentials to reduce WTWa GHG emissions compared to petroleum jet. Particularly, WTWa GHG emissions of STJ via catalytic conversion depend highly on the hydrogen source. On the other hand, ETJ offers unique opportunities to exploit extensive existing

Cosmic jets

NASA Technical Reports Server (NTRS)

Rees, M. J.

1986-01-01

The evidence that active galactic nuclei produce collimated plasma jets is summarised. The strongest radio galaxies are probably energised by relativistic plasma jets generated by spinning black holes interacting with magnetic fields attached to infalling matter. Such objects can produce e(+)-e(-) plasma, and may be relevant to the acceleration of the highest-energy cosmic ray primaries. Small-scale counterparts of the jet phenomenon within our own galaxy are briefly reviewed.

Active Flow Control Using Sweeping Jet Actuators on a Semi-Span Wing Model

NASA Technical Reports Server (NTRS)

Melton, LaTunia Pack; Koklu, Mehti

2016-01-01

Wind tunnel experiments were performed using active flow control on an unswept semispan wing model with a 30% chord trailing edge flap to aid in the selection of actuators for a planned high Reynolds number experiment. Two sweeping jet actuator sizes were investigated to determine the influence of actuator size on the active flow control system efficiency. Sweeping jet actuators with orifice sizes of 1 mm x 2 mm and 2 mm x 4 mm were selected because of the differences in actuator jet sweep angle. The parameters that were varied include actuator momentum, freestream velocity, and trailing edge flap deflection angle. Steady and unsteady pressure data, Particle Image Velocimetry data, and force and moment data were acquired to assess the performance of the two actuators. In addition to the wind tunnel experiments, benchtop studies of the actuators were performed to characterize the jets produced by each actuator. Benchtop investigations of the smaller actuator reveal that the jet exiting the actuator has a reduced sweep angle compared to published data for larger versions of this type of actuator. The larger actuator produces an oscillating jet that attaches to the external di?user walls at low supply pressures and produces the expected sweep angles. The AFC results using the smaller actuators show that while the actuators can control flow separation, the selected spacing of 3.3 cm may be too large due to the reduced sweep angle. In comparison, the spacing for the larger actuators, 6.6 cm, appears to be optimal for the Mach numbers investigated. Particle Image Velocimetry results are presented and show how the wall jets produced by the actuators cause the flow to attach to the flap surface.

Investigation of metastable production in a closed-cell dielectric capillary variable pressure He plasma jet with Ar admixture

NASA Astrophysics Data System (ADS)

Sands, Brian; Ganguly, Biswa

2011-10-01

For plasma processing applications of streamer-like atmospheric pressure plasma jets generated in a dielectric capillary, we have demonstrated that an admixture of Ar to the He gas flow greatly increases the lifetime of energetic species in the core flow through enhanced afterglow production of Ar 1s5 metastable species. To study this effect in more detail, we have used a closed-cell plasma jet that allows control over the background gas pressure and composition. We used a 20 ns risetime positive unipolar voltage pulse for excitation. A He flow with a 0-30% Ar admixture was studied using time-resolved emission and tunable diode laser absorption spectroscopy of the Ar 1s5 and He 23S metastable states. Nitrogen was used as the background gas. In pure He and pure Ar gases the He and Ar metastables respectively are produced in the first ~100 ns only in the active discharge. With Ar added to the He gas flow, He metastables produced in the active discharge are quickly quenched via Penning ionization of Ar while Ar 1s5 is enhanced over 1-2 μs in the afterglow, increasing the number density as high as 1013/cc and extending the effective lifetime up to 10 μs. This implies that He heavy particle kinetics are a key driver of enhanced afterglow plasma chemistry in plasma jets with rare gas mixtures.

Physics of neutral gas jet interaction with magnetized plasmas

NASA Astrophysics Data System (ADS)

Wang, Zhanhui; Xu, Xueqiao; Diamond, Patrick; Xu, Min; Duan, Xuru; Yu, Deliang; Zhou, Yulin; Shi, Yongfu; Nie, Lin; Ke, Rui; Zhong, Wulv; Shi, Zhongbing; Sun, Aiping; Li, Jiquan; Yao, Lianghua

2017-10-01

It is critical to understand the physics and transport dynamics during the plasma fuelling process. Plasma and neutral interactions involve the transfer of charge, momentum, and energy in ion-neutral and electron-neutral collisions. Thus, a seven field fluid model of neutral gas jet injection (NGJI) is obtained, which couples plasma density, heat, and momentum transport equations together with neutrals density and momentum transport equations of both molecules and atoms. Transport dynamics of plasma and neutrals are simulated for a complete range of discharge times, including steady state before NGJI, transport during NGJI, and relaxation after NGJI. With the trans-neut module of BOUT + + code, the simulations of mean profile variations and fueling depths during fueling have been benchmarked well with other codes and also validated with HL-2A experiment results. Both fast component (FC) and slow component (SC) of NGJI are simulated and validated with the HL-2A experimental measurements. The plasma blocking effect on the FC penetration is also simulated and validated well with the experiment. This work is supported by the National Natural Science Foundation of China under Grant No. 11575055.

Effects of gas flow on oxidation reaction in liquid induced by He/O{sub 2} plasma-jet irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Atsushi; Uchida, Giichiro, E-mail: uchida@jwri.osaka-u.ac.jp; Takenaka, Kosuke

We present here analysis of oxidation reaction in liquid by a plasma-jet irradiation under various gas flow patterns such as laminar and turbulence flows. To estimate the total amount of oxidation reaction induced by reactive oxygen species (ROS) in liquid, we employ a KI-starch solution system, where the absorbance of the KI-starch solution near 600 nm behaves linear to the total amount of oxidation reaction in liquid. The laminar flow with higher gas velocity induces an increase in the ROS distribution area on the liquid surface, which results in a large amount of oxidation reaction in liquid. However, a much fastermore » gas flow conversely results in a reduction in the total amount of oxidation reaction in liquid under the following two conditions: first condition is that the turbulence flow is triggered in a gas flow channel at a high Reynolds number of gas flow, which leads to a marked change of the spatial distribution of the ROS concentration in gas phase. Second condition is that the dimpled liquid surface is formed by strong gas flow, which prevents the ROS from being transported in radial direction along the liquid surface.« less

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

PubMed

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

2003-02-28

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

The Radio Jets and Accretion Disk in NGC 4261

NASA Astrophysics Data System (ADS)

Jones, Dayton L.; Wehrle, Ann E.; Meier, David L.; Piner, B. Glenn

2000-05-01

The structure of active galactic nucleus (AGN) accretion disks on subparsec scales can be probed through free-free absorption of synchrotron emission from the base of symmetric radio jets. For objects in which both jet and counterjet are detectable with very long baseline interferometry (VLBI), the accretion disk will cover part of the counterjet and produce diminished brightness whose angular size and depth as a function of frequency can reveal the radial distribution of free electrons in the disk. The nearby (41 Mpc, independent of H0) FR I radio galaxy NGC 4261 contains a pair of symmetric kiloparsec-scale jets. On parsec scales, radio emission from the nucleus is strong enough for detailed imaging with VLBI. We present new Very Long Baseline Array (VLBA) observations of NGC 4261 at 22 and 43 GHz, which we combine with previous observations at 1.6 and 8.4 GHz to map absorption caused by an inner accretion disk. The relative closeness of NGC 4261 combined with the high angular resolution provided by the VLBA at 43 GHz gives us a very high linear resolution, approximately 2×10-2 pc ~4000 AU ~400 Schwarzschild radii for a 5×108 Msolar black hole. The jets appear more symmetric at 1.6 GHz because of the low angular resolution available. The jets are also more symmetric at 22 and 43 GHz, presumably because the optical depth of free-free absorption is small at high frequencies. At 8.4 GHz, neither confusion effect is dominant and absorption of counterjet emission by the presumed disk is detectable. We find that the orientation of the radio jet axis is the same on parsec and kiloparsec scales, indicating that the spin axis of the inner accretion disk and black hole has remained unchanged for at least 106 (and more likely >107) yr. This suggests that a single merger event may be responsible for the supply of gas in the nucleus of NGC 4261. The jet opening angle is between 0.3d and 20° during the first 0.2 pc of the jet and must be less than 5° during the first 0

Comprehensive two-dimensional gas chromatography for the analysis of synthetic and crude-derived jet fuels.

PubMed

van der Westhuizen, Rina; Ajam, Mariam; De Coning, Piet; Beens, Jan; de Villiers, André; Sandra, Pat

2011-07-15

Fully synthetic jet fuel (FSJF) produced via Fischer-Tropsch (FT) technology was recently approved by the international aviation fuel authorities. To receive approval, comparison of FSJF and crude-derived fuel and blends on their qualitative and quantitative hydrocarbon composition was of utmost importance. This was performed by comprehensive two-dimensional gas chromatography (GC×GC) in the reversed phase mode. The hydrocarbon composition of synthetic and crude-derived jet fuels is very similar and all compounds detected in the synthetic product are also present in crude-derived fuels. Quantitatively, the synthetic fuel consists of a higher degree of aliphatic branching with less than half the aromatic content of the crude-derived fuel. GC×GC analyses also indicated the presence of trace levels of hetero-atomic impurities in the crude-derived product that were absent in the synthetic product. While clay-treatment removed some of the impurities and improved the fuel stability, the crude-derived product still contained traces of cyclic and aromatic S-containing compounds afterwards. Lower level of aromatics and the absence of sulphur are some of the factors that contribute to the better fuel stability and environmental properties of the synthetic fuel. GC×GC was further applied for the analysis of products during Jet Fuel Thermal Oxidation Testing (JFTOT), which measures deposit formation of a fuel under simulated engine conditions. JFTOT showed the synthetic fuel to be much more stable than the crude-derived fuel. Copyright © 2011 Elsevier B.V. All rights reserved.

Numerical simulation of jet mixing concepts in Tank 241-SY-101

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trent, D.S.; Michener, T.E.

The episodic gas release events (GRES) that have characterized the behavior of Tank 241-SY-101 for the past several years are thought to result from gases generated by the waste material in it that become trapped in the layer of settled solids at the bottom of the tank. Several concepts for mitigating the GREs have been proposed. One concept involves mobilizing the solid particles with mixing jets. The rationale behind this idea is to prevent formation of a consolidated layer of settled solids at the bottom of the tank, thus inhibiting the accumulation of gas bubbles in this layer. Numerical simulationsmore » were conducted using the TEMPEST computer code to assess the viability and effectiveness of the proposed jet discharge concepts and operating parameters. Before these parametric studies were commenced, a series of turbulent jet studies were conducted that established the adequacy of the TEMPEST code for this application. Configurations studied for Tank 241-SY-101 include centrally located downward discharging jets, draft tubes, and horizontal jets that are either stationary or rotating. Parameter studies included varying the jet discharge velocity, jet diameter, discharge elevation, and material properties. A total of 18 simulations were conducted and are reported in this document. The effect of gas bubbles on the mixing dynamics was not included within the scope of this study.« less

Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

PubMed Central

Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

2014-01-01

The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Yep, Tze-Wing; Agrawal, Ajay K.; Griffin, DeVon; Salzman, Jack (Technical Monitor)

2001-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2-second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet flow was significantly influenced by the gravity. The jet in microgravity was up to 70 percent wider than that in Earth gravity. The jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes a change in gravity in the drop tower.

Table-top soft x-ray microscope using laser-induced plasma from a pulsed gas jet.

PubMed

Müller, Matthias; Mey, Tobias; Niemeyer, Jürgen; Mann, Klaus

2014-09-22

An extremely compact soft x-ray microscope operating in the "water window" region at the wavelength λ = 2.88 nm is presented, making use of a long-term stable and nearly debris-free laser-induced plasma from a pulsed nitrogen gas jet target. The well characterized soft x-ray radiation is focused by an ellipsoidal grazing incidence condenser mirror. Imaging of a sample onto a CCD camera is achieved with a Fresnel zone plate using magnifications up to 500x. The spatial resolution of the recorded microscopic images is about 100 nm as demonstrated for a Siemens star test pattern.

Control of ROS and RNS productions in liquid in atmospheric pressure plasma-jet system

NASA Astrophysics Data System (ADS)

Uchida, Giichiro; Ito, Taiki; Takenaka, Kosuke; Ikeda, Junichiro; Setsuhara, Yuichi

2016-09-01

Non-thermal plasma jets are of current interest in biomedical applications such as wound disinfection and even treatment of cancer tumors. Beneficial therapeutic effects in medical applications are attributed to excited species of oxygen and nitrogen from air. However, to control the production of these species in the plasma jet is difficult because their production is strongly dependent on concentration of nitrogen and oxygen from ambient air into the plasma jet. In this study, we analyze the discharge characteristics and the ROS and RNS productions in liquid in low- and high-frequency plasma-jet systems. Our experiments demonstrated the marked effects of surrounding gas near the plasma jet on ROS and RNS productions in liquid. By controlling the surround gas, the O2 and N2 main plasma jets are selectively produced even in open air. We also show that the concentration ratio of NO2- to H2O2 in liquid is precisely tuned from 0 to 0.18 in deionized water by changing N2 gas ratio (N2 / (N2 +O2)) in the main discharge gas, where high NO2- ratio is obtained at N2 gas ratio at N2 / (N2 +O2) = 0 . 8 . The low-frequency plasma jet with controlled surrounding gas is an effective plasma source for ROS and RNS productions in liquid, and can be a useful tool for biomedical applications. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

Computational Analysis of Gravitational Effects in Low-Density Gas Jets

NASA Technical Reports Server (NTRS)

Satti, Rajani P.; Agrawal, Ajay K.

2004-01-01

This study deals with the computational analysis of buoyancy-induced instability in the nearfield of an isothermal helium jet injected into quiescent ambient air environment. Laminar, axisymmetric, unsteady flow conditions were considered for the analysis. The transport equations of helium mass fraction coupled with the conservation equations of mixture mass and momentum were solved using a staggered grid finite volume method. The jet Richardson numbers of 1.5 and 0.018 were considered to encompass both buoyant and inertial jet flow regimes. Buoyancy effects were isolated by initiating computations in Earth gravity and subsequently, reducing gravity to simulate the microgravity conditions. Computed results concur with experimental observations that the periodic flow oscillations observed in Earth gravity subside in microgravity.

Primary atomization of liquid jets issuing from rocket engine coaxial injectors

NASA Astrophysics Data System (ADS)

Woodward, Roger D.

1993-01-01

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

Detection of radio emission from the jet in Centaurus A

NASA Technical Reports Server (NTRS)

Schreier, E. J.; Burns, J. O.; Feigelson, E. D.

1981-01-01

The VLA has detected radio emission from the X-ray jet in Centaurus A, at 20 and 6 cm, whose radio morphology is similar to that of the X-ray jet. It is suggested that the same population of relativistic electrons is responsible for both radio and X-ray synchrotron emission, in which case in situ acceleration of electrons in the knots would be mandatory. The relativistic beam may alternatively heat the surrounding gas, resulting in X-ray emission. The static confinement of the knots of the jet seems to be accomplished by the presence of the ambient hot gas in the galaxy. The galaxy's nucleus has an inverted spectrum at radio frequencies, and it is noted that the jet is as bright as the nucleus at low frequencies.

Exploring Jets from a Supermassive Black Hole

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-06-01

What are the feeding and burping habits of the supermassive black holes peppering the universe? In a new study, observations of one such monster reveal more about the behavior of its powerful jets.Beams from BehemothsAcross the universe, supermassive black holes of millions to billions of solar masses lie at the centers of galaxies, gobbling up surrounding material. But not all of the gas and dust that spirals in toward a black hole is ultimately swallowed! A large fraction of it can instead be flung out into space again, in the form of enormous, powerful jets that extend for thousands or even millions of light-years in opposite directions.M87, shown in this Hubble image, is a classic example of a nearby (55 million light-years distant) supermassive black hole with a visible, collimated jet. Its counter-jet isnt seen because relativistic effects make the receding jet appear less bright. [The Hubble Heritage Team (STScI/AURA) and NASA/ESA]What causes these outflows to be tightly beamed collimated in the form of jets, rather than sprayed out in all directions? Does the pressure of the ambient medium the surrounding gas and dust that the jet is injected into play an important role? In what regions do these jets accelerate and decelerate? There are many open questions that scientists hope to understand by studying some of the active black holes with jets that live closest to us.Eyes on a Nearby GiantIn a new study led by Satomi Nakahara (The Graduate University for Advanced Studies in Japan), a team of scientists has used multifrequency Very Long Baseline Array (VLBA) and Very Long Array (VLA) images to explore jets emitted from a galaxy just 100 million light-years away: NGC 4261.This galaxys (relatively) close distance as well as the fact that were viewing it largely from the side, so we can clearly see both of its polar jets allows us to observe in detail the structure and intensity of its jets as a function of their distance from the black hole. Nakahara and

Influence of jet-cooking Prowashonupana barley flour on phenolic composition, antioxidant activities, and viscoelastic properties

USDA-ARS?s Scientific Manuscript database

The influence of jet-cooking Prowashonupana barley flour on total phenolic contents, antioxidant activities, water holding capacities, and viscoelastic properties was studied. Barley flour was jet-cooked without or with pH adjustment at 7, 9, or 11. Generally, the free phenolic content and antioxi...

Use of inert gas jets to measure the forces required for mechanical gene transfection

PubMed Central

2012-01-01

Background Transferring genes and drugs into cells is central to how we now study, identify and treat diseases. Several non-viral gene therapy methods that rely on the mechanical disruption of the plasma membrane have been proposed, but the success of these methods has been limited due to a lack of understanding of the mechanical parameters that lead to cell membrane permeability. Methods We use a simple jet of inert gas to induce local transfection of plasmid DNA both in vitro (HeLa cells) and in vivo (chicken chorioallantoic membrane). Five different capillary tube inner diameters and three different gases were used to treat the cells to understand the dependency of transfection efficiency on the dynamic parameters. Results The simple setup has the advantage of allowing us to calculate the forces acting on cells during transfection. We found permeabilization efficiency was related to the dynamic pressure of the jet. The range of dynamic pressures that led to transfection in HeLa cells was small (200 ± 20 Pa) above which cell stripping occurred. We determined that the temporary pores allow the passage of dextran up to 40 kDa and reclose in less than 5 seconds after treatment. The optimized parameters were also successfully tested in vivo using the chorioallantoic membrane of the chick embryo. Conclusions The results show that the number of cells transfected with the plasmid scales with the dynamic pressure of the jet. Our results show that mechanical methods have a very small window in which cells are permeabilized without injury (200 to 290 Pa). This simple apparatus helps define the forces needed for physical cell transfection methods. PMID:22963645

AGN jet power, formation of X-ray cavities, and FR I/II dichotomy in galaxy clusters

NASA Astrophysics Data System (ADS)

Fujita, Yutaka; Kawakatu, Nozomu; Shlosman, Isaac

2016-04-01

We investigate the ability of jets in active galactic nuclei to break out of the ambient gas with sufficiently large advance velocities. Using observationally estimated jet power, we analyze 28 bright elliptical galaxies in nearby galaxy clusters. Because the gas density profiles in the innermost regions of galaxies have not been resolved so far, we consider two extreme cases for temperature and density profiles. We also follow two types of evolution for the jet cocoons: being driven by the pressure inside the cocoon [Fanaroff-Riley (FR) type I], and being driven by the jet momentum (FR type II). Our main result is that regardless of the assumed form of the density profiles, jets with observed powers of ≲1044 erg s-1 are not powerful enough to evolve as FR II sources. Instead, they evolve as FR I sources and appear to be decelerated below the buoyant velocities of the cocoons when jets were propagating through the central dense regions of the host galaxies. This explains why FR I sources are more frequent than FR II sources in clusters. Furthermore, we predict the sizes of X-ray cavities from the observed jet powers and compare them with the observed ones-they are consistent within a factor of two if the FR I type evolution is realized. Finally, we find that the jets with a power ≳1044 erg s-1 are less affected by the ambient medium, and some of them, but not all, could serve as precursors of the FR II sources.

Reversing cooling flows with AGN jets: shock waves, rarefaction waves and trailing outflows

NASA Astrophysics Data System (ADS)

Guo, Fulai; Duan, Xiaodong; Yuan, Ye-Fei

2018-01-01

The cooling flow problem is one of the central problems in galaxy clusters, and active galactic nucleus (AGN) feedback is considered to play a key role in offsetting cooling. However, how AGN jets heat and suppress cooling flows remains highly debated. Using an idealized simulation of a cool-core cluster, we study the development of central cooling catastrophe and how a subsequent powerful AGN jet event averts cooling flows, with a focus on complex gasdynamical processes involved. We find that the jet drives a bow shock, which reverses cooling inflows and overheats inner cool-core regions. The shocked gas moves outward in a rarefaction wave, which rarefies the dense core and adiabatically transports a significant fraction of heated energy to outer regions. As the rarefaction wave propagates away, inflows resume in the cluster core, but a trailing outflow is uplifted by the AGN bubble, preventing gas accumulation and catastrophic cooling in central regions. Inflows and trailing outflows constitute meridional circulations in the cluster core. At later times, trailing outflows fall back to the cluster centre, triggering central cooling catastrophe and potentially a new generation of AGN feedback. We thus envisage a picture of cool cluster cores going through cycles of cooling-induced contraction and AGN-induced expansion. This picture naturally predicts an anti-correlation between the gas fraction (or X-ray luminosity) of cool cores and the central gas entropy, which may be tested by X-ray observations.

Experimental investigation of adiabatic compression and heating using collision of an MHD-driven jet with a gas target cloud for magnetized target fusion

NASA Astrophysics Data System (ADS)

Seo, Byonghoon; Li, Hui; Bellan, Paul

2017-10-01

We are studying magnetized target fusion using an experimental method where an imploding liner compressing a plasma is simulated by a high-speed MHD-driven plasma jet colliding with a gas target cloud. This has the advantage of being non-destructive so orders of magnitude more shots are possible. Since the actual density and temperature are much more modest than fusion-relevant values, the goal is to determine the scaling of the increase in density and temperature when an actual experimental plasma is adiabatically compressed. Two new-developed diagnostics are operating and providing data. The first new diagnostic is a fiber-coupled interferometer which measures line-integrated electron density not only as a function of time, but also as a function of position along the jet. The second new diagnostic is laser Thomson scattering which measures electron density and temperature at the location where the jet collides with the cloud. These diagnostics show that when the jet collides with a target cloud the jet slows down substantially and both the electron density and temperature increase. The experimental measurements are being compared with 3D MHD and hybrid kinetic numerical simulations that model the actual experimental geometry.

A Hydrogen Peroxide Hot-Jet Simulator for Wind-Tunnel Tests of Turbojet-Exit Models

NASA Technical Reports Server (NTRS)

Runckel, Jack F.; Swihart, John M.

1959-01-01

A turbojet-engine-exhaust simulator which utilizes a hydrogen peroxide gas generator has been developed for powered-model testing in wind tunnels with air exchange. Catalytic decomposition of concentrated hydrogen peroxide provides a convenient and easily controlled method of providing a hot jet with characteristics that correspond closely to the jet of a gas turbine engine. The problems associated with simulation of jet exhausts in a transonic wind tunnel which led to the selection of a liquid monopropellant are discussed. The operation of the jet simulator consisting of a thrust balance, gas generator, exit nozzle, and auxiliary control system is described. Static-test data obtained with convergent nozzles are presented and shown to be in good agreement with ideal calculated values.

Measurement of activated species generated by AC power excited non-equilibrium atmospheric pressure Ar plasma jet with air engulfment

NASA Astrophysics Data System (ADS)

Takeda, Keigo; Ishikawa, Kenji; Tanaka, Hiromasa; Kano, Hiroyuki; Sekine, Makoto; Hori, Masaru

2013-09-01

Non-equilibrium atmospheric pressure plasma jet (NEAPPJ) is very attractive tool for bio and medical applications. In the plasma treatments, samples are typically located at a far region from main discharge, and treated in open air without purge gases. Influence of air engulfment on generation of activated species in the NEAPPJ in open air is a large issue for the application. In this study, the AC excited argon NEAPPJ with the gas flow rate of 2 slm was generated under the open air condition. The densities of the grand state nitrogen monoxide (NO) and the ground state O atom generated by the NEAPPJ were measured by laser induced fluorescence spectroscopy and vacuum ultraviolet absorption spectroscopy. The length of the plasma jet was around 10 mm. Up to 10 mm, the NO density increased with increasing the distance from plasma head, and then saturated in remote region of plasma. On the other hand, the O atom density decreased from 1014 to 1013 cm-3 with increasing the distance. Especially, the amount of decrease in O atom density became the largest at the plasma edge. We will discuss the generation and loss processes of activated species generated in the NEAPPJ with the measurement results using spectroscopic methods.

Implementation of and measurement with the LIPA technique in a subsonic jet

NASA Technical Reports Server (NTRS)

Falco, R. E.

1994-01-01

LIPA (Laser Induced Photochemical Anemometry) was used to measure velocity, vorticity, Reynolds stress, and turbulent intensity distributions in a subsonic jet. The jet region of interest was the area close to the jet-orifice. The LIPA-technique is a nonintrusive quantitative flow visualization technique, consisting of tracking a phosphorescing grid of fluid particles, which is impressed by laser-beams directed into the flow. The phosphorescence of biacetyl gas was used to enable tracking of the impressed light grid. In order to perform measurements in a jet, LIPA was developed and implemented for the specific flow requirements. Nitrogen was used as the carrier gas to avoid quenching of the phosphorescent radiation of the tracer gas biacetyl by ambient oxygen. The use of sulfur dioxide to sensitize phosphorescent emission of biacetyl was examined. Preliminary data was used in a discussion of the potential of the LIPA technique.

Study on dynamics of the influence exerted by plasma on gas flow field in non-thermal atmospheric pressure plasma jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qaisrani, M. Hasnain; Xian, Yubin, E-mail: yubin.xian@hotmail.com; Li, Congyun

2016-06-15

In this paper, first, steady state of the plasma jet at different operating conditions is investigated through Schlieren photography with and without applying shielding gas. Second, the dynamic process for the plasma impacting on the gas flow field is studied. When the discharge is ignited, reduction in laminar flow occurs. However, when the gas flow rate is too low or too high, this phenomenon is not obvious. What is more, both frequency and voltage have significant impact on the effect of plasma on the gas flow, but the former is more significant. Shielding gas provides a curtain for plasma tomore » propagate further. High speed camera along with Schlieren photography is utilized to study the impact of plasma on the gas flow when plasma is switched on and off. The transition of the gas flow from laminar to turbulent or vice versa happens right after the turbulent front. It is concluded that appearance and propagation of turbulence front is responsible for the transition of the flow state.« less

Effect of increased fuel temperature on emissions of oxides of nitrogen from a gas turbine combustor burning ASTM jet-A fuel

NASA Technical Reports Server (NTRS)

Marchionna, N. R.

1974-01-01

An annular gas turbine combustor was tested with heated ASTM Jet-A fuel to determine the effect of increased fuel temperature on the formation of oxides of nitrogen. Fuel temperature ranged from ambient to 700 K. The NOx emission index increased at a rate of 6 percent per 100 K increase in fuel temperature.

Development of a jet pump-assisted arterial heat pipe

NASA Technical Reports Server (NTRS)

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

1977-01-01

The development of a jet pump assisted arterial heat pipe is described. The concept utilizes a built-in capillary driven jet pump to remove vapor and gas from the artery and to prime it. The continuous pumping action also prevents depriming during operation of the heat pipe. The concept is applicable to fixed conductance and gas loaded variable conductance heat pipes. A theoretical model for the jet pump assisted arterial heat pipe is presented. The model was used to design a prototype for laboratory demonstration. The 1.2 m long heat pipe was designed to transport 500 watts and to prime at an adverse elevation of up to 1.3 cm. The test results were in good agreement with the theoretical predictions. The heat pipe carried as much as 540 watts and was able to prime up to 1.9 cm. Introduction of a considerable amount of noncondensible gas had no adverse effect on the priming capability.

Cratering Soil by Impinging Jets of Gas, with Application to Landing Rockets on Planetary Surfaces

NASA Technical Reports Server (NTRS)

Metzger, Philip T.; Vu, B. T.; Taylor, D. E.; Kromann, M. J.; Fuchs, M.; Yutko, B.; Dokos, A.; Immer, Christopher D.; Lane, J. E.; Dunkel, Michael B.;

Numerical Investigation of the Hydrogen Jet Flammable Envelope Extent with Account for Unsteady Phenomena

NASA Astrophysics Data System (ADS)

Chernyavsky, Boris; Benard, Pierre

2010-11-01

An important aspect of safety analysis in hydrogen applications is determination of the extent of flammable gas envelope in case of hydrogen jet release. Experimental investigations had shown significant disagreements between the extent of average flammable envelope predicted by steady-state numerical methods, and the region observed to support ignition, with proposed cause being non-steady jet phenomena resulting in significant variations of instantaneous gas concentration and velocity fields in the jet. In order to investigate the influence of these transient phenomena, a numerical investigation of hydrogen jet at low Mach number had been performed using unsteady Large Eddy Simulation. Instantaneous hydrogen concentration and velocity fields were monitored to determine instantaneous flammable envelope. The evolution of the instantaneous fields, including the development of the turbulence structures carrying hydrogen, their extent and frequency, and their relation with averaged fields had been characterized. Simulation had shown significant variability of the flammable envelope, with jet flapping causing shedding of large scale rich and lean gas pockets from the main jet core, which persist for significant times and substantially alter the extent of flammability envelope.

The first science result with the JENSA gas-jet target: Confirmation and study of a strong subthreshold F 18 ( p , α ) O 15 resonance

DOE PAGES

Bardayan, D. W.; Chipps, K. A.; Ahn, S.; ...

2015-11-28

The astrophysical 18F( p,α) 15O rate determines, in large part, the extent to which the observable radioisotope 18F is produced in novae. This rate, however, has been extremely uncertain owing to the unknown properties of a strong subthreshold resonance and its possible interference with higher-lying resonances. In addition, the new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has been used for the first time to determine the spin of this important resonance and significantly reduce uncertainties in the 18F( p,α) 15O rate.

The first science result with the JENSA gas-jet target: Confirmation and study of a strong subthreshold F 18 ( p , α ) O 15 resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bardayan, D. W.; Chipps, K. A.; Ahn, S.

The astrophysical 18F( p,α) 15O rate determines, in large part, the extent to which the observable radioisotope 18F is produced in novae. This rate, however, has been extremely uncertain owing to the unknown properties of a strong subthreshold resonance and its possible interference with higher-lying resonances. In addition, the new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has been used for the first time to determine the spin of this important resonance and significantly reduce uncertainties in the 18F( p,α) 15O rate.

Studies of supersonic, radiative plasma jet interaction with gases at the Prague Asterix Laser System facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicolaie, Ph.; Stenz, C.; Tikhonchuk, V.

2008-08-15

The interaction of laser driven jets with gas puffs at various pressures is investigated experimentally and is analyzed by means of numerical tools. In the experiment, a combination of two complementary diagnostics allowed to characterize the main structures in the interaction zone. By changing the gas composition and its density, the plasma cooling time can be controlled and one can pass from a quasiadiabatic outflow to a strongly radiation cooling jet. This tuning yields hydrodynamic structures very similar to those seen in astrophysical objects; the bow shock propagating through the gas, the shocked materials, the contact discontinuity, and the Machmore » disk. From a dimensional analysis, a scaling is made between both systems and shows the study relevance for the jet velocity, the Mach number, the jet-gas density ratio, and the dissipative processes. The use of a two-dimensional radiation hydrodynamic code, confirms the previous analysis and provides detailed structure of the interaction zone and energy repartition between jet and surrounding gases.« less

Jovian Jet Stream

NASA Image and Video Library

2018-05-31

See a jet stream speeding through Jupiter's atmosphere in this new view taken by NASA's Juno spacecraft. The jet stream, called Jet N2, was captured along the dynamic northern temperate belts of the gas giant planet. It is the white stream visible from top left to bottom right in the image. The color-enhanced image was taken at 10:34 p.m. PST on May 23 (1:34 a.m. EST on May 24), as Juno performed its 13th close flyby of Jupiter. At the time the image was taken, the spacecraft was about 3,516 miles (5,659 kilometers) from the tops of the clouds of the planet at a northern latitude of 32.9 degrees. Citizen scientists Gerald Eichstädt and Seán Doran created this image using data from the spacecraft's JunoCam imager. The view is a composite of several separate JunoCam images that were re-projected, blended, and healed. https://photojournal.jpl.nasa.gov/catalog/PIA22422

Gravitational Effects on Near Field Flow Structure of Low Density Gas Jets

NASA Technical Reports Server (NTRS)

Griffin, D. W.; Yep, T. W.; Agrawal, A. K.

2005-01-01

Experiments were conducted in Earth gravity and microgravity to acquire quantitative data on near field flow structure of helium jets injected into air. Microgravity conditions were simulated in the 2.2- second drop tower at NASA Glenn Research Center. The jet flow was observed by quantitative rainbow schlieren deflectometry, a non-intrusive line of site measurement technique for the whole field. The flow structure was characterized by distributions of angular deflection and helium mole percentage obtained from color schlieren images taken at 60 Hz. Results show that the jet in microgravity was up to 70 percent wider than that in Earth gravity. The global jet flow oscillations observed in Earth gravity were absent in microgravity, providing direct experimental evidence that the flow instability in the low density jet was buoyancy induced. The paper provides quantitative details of temporal flow evolution as the experiment undergoes change in gravity in the drop tower.

Experiments in dilution jet mixing

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Srinivasan, R.; Berenfeld, A.

1983-01-01

Experimental results are given on the mixing of a single row of jets with an isothermal mainstream in a straight duct, to include flow and geometric variations typical of combustion chambers in gas turbine engines. The principal conclusions reached from these experiments were: at constant momentum ratio, variations in density ratio have only a second-order effect on the profiles; a first-order approximation to the mixing of jets with a variable temperature mainstream can be obtained by superimposing the jets-in-an isothermal-crossflow and mainstream profiles; flow area convergence, especially injection-wall convergence, significantly improves the mixing; for opposed rows of jets, with the orifice centerlines in-line, the optimum ratio of orifice spacing to duct height is one half of the optimum value for single side injection at the same momentum ratio; and for opposed rows of jets, with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is twice the optimum value for single side injection at the same momentum ratio.

Experiments in dilution jet mixing

NASA Technical Reports Server (NTRS)

Holdeman, J. D.; Srinivasan, R.; Berenfeld, A.

1983-01-01

Experimental results are presented on the mixing of a single row of jets with an isothermal mainstream in a straight duct, with flow and geometric variations typical of combustion chambers in gas turbine engines included. It is found that at a constant momentum ratio, variations in the density ratio have only a second-order effect on the profiles. A first-order approximation to the mixing of jets with a variable temperature mainstream can, it is found, be obtained by superimposing the jets-in-an-isothermal-crossflow and mainstream profiles. Another finding is that the flow area convergence, especially injection-wall convergence, significantly improves the mixing. For opposed rows of jets with the orifice cone centerlines in-line, the optimum ratio of orifice spacing to duct height is determined to be 1/2 of the optimum value for single injection at the same momentum ratio. For opposed rows of jets with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is found to be twice the optimum value for single side injection at the same momentum ratio.

Relativistic hydrodynamic jets in the intracluster medium

NASA Astrophysics Data System (ADS)

Choi, Eunwoo

2017-08-01

We have performed the first three-dimensional relativistic hydrodynamic simulations of extragalactic jets of pure leptonic and baryonic plasma compositions propagating into a hydrostatic intracluster medium (ICM) environment. The numerical simulations use a general equation of state for a multicomponent relativistic gas, which closely reproduces the Synge equation of state for a relativistic perfect gas. We find that morphological and dynamical differences between leptonic and baryonic jets are much less evident than those between hot and cold jets. In all these models, the jets first propagate with essentially constant velocities within the core radius of the ICM and then accelerate progressively so as to increase the jet advance velocity by a factor of between 1.2 and 1.6 at the end of simulations, depending upon the models. The temporal evolution of the average cavity pressure is not consistent with that expected by the extended theoretical model even if the average cavity pressure decreases as a function of time with a power law. Our simulations produce synthetic radio images that are dominated by bright hot spots and appear similar to observations of the extended radio galaxies with collimated radio jets. These bright radio lobes would be visible as dark regions in X-ray images and are morphologically similar to observed X-ray cavities in the ICM. This supports the expectation that the bow shock surrounding the head of the jet is important mechanism for producing X-ray cavities in the ICM. Although there are quantitative differences among the models, the total radio and X-ray intensity curves show qualitatively similar trends in all of them.

Schlieren Measurements of Buoyancy Effects on Flow Transition in Low-Density Gas Jets

NASA Technical Reports Server (NTRS)

Pasumarthi, Kasyap S.; Agrawal, Ajay K.

2005-01-01

The transition from laminar to turbulent flow in helium jets discharged into air was studied using Rainbow Schlieren Deflectometry technique. In particular, the effects of buoyancy on jet oscillations and flow transition length were considered. Experiments to simulate microgravity were conducted in the 2.2s drop tower at NASA Glenn Research Center. The jet Reynolds numbers varied from 800 to1200 and the jet Richardson numbers ranged between 0.01 and 0.004. Schlieren images revealed substantial variations in the flow structure during the drop. Fast Fourier Transform (FFT) analysis of the data obtained in Earth gravity experiments revealed the existence of a discrete oscillating frequency in the transition region, which matched the frequency in the upstream laminar regime. In microgravity, the transition occurred farther downstream indicating laminarization of the jet in the absence of buoyancy. The amplitude of jet oscillations was reduced by up to an order of magnitude in microgravity. Results suggest that jet oscillations were buoyancy induced and that the brief microgravity period may not be sufficient for the oscillations to completely subside.

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.

Assessing Jet-Induced Spatial Mixing in a Rich, Reacting Crossflow

NASA Technical Reports Server (NTRS)

Demayo, T. N.; Leong, M. Y.; Samuelsen, G. S.

2004-01-01

In many advanced low NOx gas turbine combustion techniques, such as rich-burn/quick-mix/lean-burn (RQL), jet mixing in a reacting, hot, fuel-rich crossflow plays an important role in minimizing all pollutant emissions and maximizing combustion efficiency. Assessing the degree of mixing and predicting jet penetration is critical to the optimization of the jet injection design strategy. Different passive scalar quantities, including carbon, oxygen, and helium are compared to quantify mixing in an atmospheric RQL combustion rig under reacting conditions. The results show that the O2-based jet mixture fraction underpredicts the C-based mixture fraction due to jet dilution and combustion, whereas the He tracer overpredicts it possibly due to differences in density and diffusivity. The He-method also exhibits significant scatter in the mixture fraction data that can most likely be attributed to differences in gas density and turbulent diffusivity. The jet mixture fraction data were used to evaluate planar spatial unmixedness, which showed good agreement for all three scalars. This investigation suggests that, with further technique refinement, O2 or a He tracer could be used instead of C to determine the extent of reaction and mixing in an RQL combustor.

Analysis of penetration and mixing of gas jets in supersonic cross flow

NASA Technical Reports Server (NTRS)

Billig, F. S.; Schetz, J. A.

1992-01-01

The JETPEN analysis for gas jets in a supersonic cross flow developed earlier at APL/JHU has been extended in several important ways. First, the treatment of cases with injection at angles other than 90 deg has been redone. Next, the second of the three regions formerly treated has been eliminated. Third, the region downstream of the Mach disk for underexpanded cases has been reformulated such that turbulent entrainment of main stream fluid into the plume is modeled, and the equations of motion are solved marching downstream. These changes now permit prediction of the variation in composition, mixing area growth and all other flow variables along the plume. The analysis has been verified by comparison of predictions and experiment over a wide range of conditions. The result is an analysis capable of reliable predictions of the major flowfield variables that can be run on a PC.

Improved Stirling engine performance using jet impingement

NASA Technical Reports Server (NTRS)

Johnson, D. C.; Britt, E. J.; Thieme, L. G.

1982-01-01

Of the many factors influencing the performance of a Stirling engine, that of transferring the combustion gas heat into the working fluid is crucial. By utilizing the high heat transfer rates obtainable with a jet impingement heat transfer system, it is possible to reduce the flame temperature required for engine operation. Also, the required amount of heater tube surface area may be reduced, resulting in a decrease in the engine nonswept volume and a related increase in engine efficiency. A jet impingement heat transfer system was designed by Rasor Associates, Inc., and tested in the GPU-3 Stirling engine at the NASA Lewis Research Center. For a small penalty in pumping power (less than 0.5% of engine output) the jet impingement heat transfer system provided a higher combustion-gas-side heat transfer coefficient and a smoothing of heater temperature profiles resulting in lower combustion system temperatures and a 5 to 8% increase in engine power output and efficiency.

An experimental study of planar heterogeneous supersonic confined jets

NASA Astrophysics Data System (ADS)

Tanis, Frederick J., Jr.

1994-12-01

The effects of varying the exit pressure of a supersonic helium jet exhausting coaxially with two parallel supersonic air streams into a constant area duct were investigated. The method used to evaluate the mass entrainment rate was to measure helium molar concentration profiles and mass flux across the duct using a binary gas probe then calculate the mass entrainment into the helium jet. In order to conduct this study a novel binary gas probe was developed which allowed helium concentration and mass flux data to be obtained during continuous traverses across the supersonic flowfield. High exit pressure ratio (EPR) led to improved overall mixing compared to the baseline case with an EPR near unity. The high EPR caused low mass entrainment along the jet shear layers due to high convective Mach numbers and velocity ratios, but the high EPR caused oblique shocks to form which reflected off the duct walls and intersected with the helium jet several times causing significant mass entrainment due to numerous shock-shear layer interactions (SSLI's). A correlation between the vorticity generated during a SSLI and the mass entrainment into the jet was developed.

Modelling of plasma generation and thin film deposition by a non-thermal plasma jet at atmospheric pressure

NASA Astrophysics Data System (ADS)

Sigeneger, F.; Becker, M. M.; Foest, R.; Loffhagen, D.

2016-09-01

The gas flow and plasma in a miniaturized non-thermal atmospheric pressure plasma jet for plasma enhanced chemical vapour deposition has been investigated by means of hydrodynamic modelling. The investigation focuses on the interplay between the plasma generation in the active zone where the power is supplied by an rf voltage to the filaments, the transport of active plasma particles due to the gas flow into the effluent, their reactions with the thin film precursor molecules and the transport of precursor fragments towards the substrate. The main features of the spatially two-dimensional model used are given. The results of the numerical modelling show that most active particles of the argon plasma are mainly confined within the active volume in the outer capillary of the plasma jet, with the exception of molecular argon ions which are transported remarkably into the effluent together with slow electrons. A simplified model of the precursor kinetics yields radial profiles of precursor fragment fluxes onto the substrate, which agree qualitatively with the measured profiles of thin films obtained by static film deposition experiments.

RESOLVING THE GEOMETRY OF THE INNERMOST RELATIVISTIC JETS IN ACTIVE GALACTIC NUCLEI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Algaba, J. C.; Lee, S. S.; Nakamura, M.

2017-01-01

In the current paradigm, it is believed that the compact VLBI radio core of radio-loud active galactic nuclei (AGNs) represents the innermost upstream regions of relativistic outflows. These regions of AGN jets have generally been modeled by a conical outflow with a roughly constant opening angle and flow speed. Nonetheless, some works suggest that a parabolic geometry would be more appropriate to fit the high energy spectral distribution properties and it has been recently found that, at least in some nearby radio galaxies, the geometry of the innermost regions of the jet is parabolic. We compile here multi-frequency core sizes of archivalmore » data to investigate the typically unresolved upstream regions of the jet geometry of a sample of 56 radio-loud AGNs. Data combined from the sources considered here are not consistent with the classic picture of a conical jet starting in the vicinity of the super-massive black hole (SMBH), and may exclude a pure parabolic outflow solution, but rather suggest an intermediate solution with quasi-parabolic streams, which are frequently seen in numerical simulations. Inspection of the large opening angles near the SMBH and the range of the Lorentz factors derived from our results support our analyses. Our result suggests that the conical jet paradigm in AGNs needs to be re-examined by millimeter/sub-millimeter VLBI observations.« less

Laser-Sharp Jet Splits Water

NASA Technical Reports Server (NTRS)

2008-01-01

A jet of gas firing out of a very young star can be seen ramming into a wall of material in this infrared image from NASA's Spitzer Space Telescope.

The young star, called HH 211-mm, is cloaked in dust and can't be seen. But streaming away from the star are bipolar jets, color-coded blue in this view. The pink blob at the end of the jet to the lower left shows where the jet is hitting a wall of material. The jet is hitting the wall so hard that shock waves are being generated, which causes ice to vaporize off dust grains. The shock waves are also heating material up, producing energetic ultraviolet radiation. The ultraviolet radiation then breaks the water vapor molecules apart.

The red color at the end of the lower jet represents shock-heated iron, sulfur and dust, while the blue color in both jets denotes shock-heated hydrogen molecules.

HH 211-mm is part of a cluster of about 300 stars, called IC 348, located 1,000 light-years away in the constellation Perseus.

This image is a composite of infrared data from Spitzer's infrared array camera and its multiband imaging photometer. Light with wavelengths of 3.6 and 4.5 microns is blue; 8-micron-light is green; and 24-micron light is red.

Mixing in Gas Phase Turbulent Jets

DTIC Science & Technology

1988-01-01

jet centerline with about 4 ZD per line 81 5-14 Comparison of flame lengths reported by Dahm et al. (1984) with those estimated from the measured PDFs...the flame length studies of Weddell (1952) and Dahm et al. (1984) . Their work points to Re 0 M 3,000 as the threshold where the degree of molecular...increased abundance at high C/C, however, offsets - 84 - part of the 8% loss in mean concentration when a flame length is estimated from the measured PDF

PALS laser-driven radiative jets for astrophysical and ICF applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pisarczyk, T.; Kasperczuk, A.; Stenz, Ch.

2008-03-19

High speed, well-collimated plasma jets were generated in the interaction of defocused single laser beam with planar, massive Cu target. The experiment was carried out at the iodine laser facility (Prague Asterix Laser System--PALS) using the third harmonic beam (0.438 {mu}m) with a pulse duration of 250 ps (FWHM) and an energy of 100 J. The information about geometry of plasma expansion, plasma dynamics and electron density were obtained by means of a 3-frame interferometric system. The plasma jet parameters reach the following values: the velocity up to 7x10{sup 7} cm/s, the internal Mach number greater than 10 and themore » electron density above 10{sup 19} cm{sup -3}. The jet characteristics are appropriate for the astrophysical and ICF applications. To ensure the interaction of this jet with gas or plasma as an ambient medium, a high-pressure supersonic gas nozzle was used, which created a cylindrical column of Ar or He. The results of first experiments dedicated to studies of collision of such a jet with a gas cloud are also presented. They clearly show the effect of shocks formation in ambient gases (He and Ar) due to the jet action. In the case of He the shock waves have usually a conical shape with a thickness of 1-1.5 mm, whereas in the case of Ar, the shock wave configuration is more complex and its thickness is less than 1 mm.« less

Prediction of Turbulent Jet Mixing Noise Reduction by Water Injection

NASA Technical Reports Server (NTRS)

Kandula, Max

2008-01-01

A one-dimensional control volume formulation is developed for the determination of jet mixing noise reduction due to water injection. The analysis starts from the conservation of mass, momentum and energy for the confrol volume, and introduces the concept of effective jet parameters (jet temperature, jet velocity and jet Mach number). It is shown that the water to jet mass flow rate ratio is an important parameter characterizing the jet noise reduction on account of gas-to-droplet momentum and heat transfer. Two independent dimensionless invariant groups are postulated, and provide the necessary relations for the droplet size and droplet Reynolds number. Results are presented illustrating the effect of mass flow rate ratio on the jet mixing noise reduction for a range of jet Mach number and jet Reynolds number. Predictions from the model show satisfactory comparison with available test data on perfectly expanded hot supersonic jets. The results suggest that significant noise reductions can be achieved at increased flow rate ratios.

Enhanced fuel efficiency on tractor-trailers using synthetic jet-based active flow control

NASA Astrophysics Data System (ADS)

Amitay, Michael; Menicovich, David; Gallardo, Daniele

2016-04-01

The application of piezo-electrically-driven synthetic-jet-based active flow control to reduce drag on tractor-trailers was explored experimentally in wind tunnel testing as well as full-scale road tests. Aerodynamic drag accounts for more than 50% of the usable energy at highway speeds, a problem that applies primarily to trailer trucks. Therefore, a reduction in aerodynamic drag results in large saving of fuel and reduction in CO2 emissions. The active flow control technique that is being used relies on a modular system comprised of distributed, small, highly efficient actuators. These actuators, called synthetic jets, are jets that are synthesized at the edge of an orifice by a periodic motion of a piezoelectric diaphragm(s) mounted on one (or more) walls of a sealed cavity. The synthetic jet is zero net mass flux (ZNMF), but it allows momentum transfer to flow. It is typically driven near diaphragm and/or cavity resonance, and therefore, small electric input [O(10W)] is required. Another advantage of this actuator is that no plumbing is required. The system doesn't require changes to the body of the truck, can be easily reconfigured to various types of vehicles, and consumes small amounts of electrical power from the existing electrical system of the truck. Preliminary wind tunnel results showed up to 18% reduction in fuel consumption, whereas road tests also showed very promising results.

Effect of high surface area activated carbon on thermal degradation of jet fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gergova, K.; Eser, S.; Arumugam, R.

1995-05-01

Different solid carbons added to jet fuel during thermal stressing cause substantial changes in pyrolytic degradation reactions. Activated carbons, especially high surface area activated carbons were found to be very effective in suppressing solid deposition on metal reactor walls during stressing at high temperatures (425 and 450{degrees}C). The high surface area activated carbon PX-21 prevented solid deposition on reactor walls even after 5h at 450{degrees}C. The differences seen in the liquid product composition when activated carbon is added indicated that the carbon surfaces affect the degradation reactions. Thermal stressing experiments were carried out on commercial petroleum-derived JPTS jet fuel. Wemore » also used n-octane and n-dodecane as model compounds in order to simplify the study of the chemical changes which take place upon activated carbon addition. In separate experiments, the presence of a hydrogen donor, decalin, together with PX-21 was also studied.« less

The SINFONI survey of powerful radio galaxies at z 2: Jet-driven AGN feedback during the Quasar Era

NASA Astrophysics Data System (ADS)

Nesvadba, N. P. H.; De Breuck, C.; Lehnert, M. D.; Best, P. N.; Collet, C.

2017-03-01

We present VLT/SINFONI imaging spectroscopy of the rest-frame optical emission lines of warm ionized gas in 33 powerful radio galaxies at redshifts z ≳ 2, which are excellent sites to study the interplay of rapidly accreting active galactic nuclei and the interstellar medium of the host galaxy in the very late formation stages of massive galaxies. Our targets span two orders of magnitude in radio size (2-400 kpc) and kinetic jet energy (a few 1046- almost 1048 erg s-1). All sources have complex gas kinematics with broad line widths up to 1300 km s-1. About half have bipolar velocity fields with offsets up to 1500 km s-1 and are consistent with global back-to-back outflows. The others have complex velocity distributions, often with multiple abrupt velocity jumps far from the nucleus of the galaxy, and are not associated with a major merger in any obvious way. We present several empirical constraints that show why gas kinematics and radio jets seem to be physically related in all galaxies of the sample. The kinetic energy in the gas from large scale bulk and local outflow or turbulent motion corresponds to a few 10-3 to 10-2 of the kinetic energy output of the radio jet. In galaxies with radio jet power ≳ 1047 erg s-1, the kinetic energy in global back-to-back outflows dominates the total energy budget of the gas, suggesting that bulk motion of outflowing gas encompasses the global interstellar medium. This might be facilitated by the strong gas turbulence, as suggested by recent analytical work. We compare our findings with recent hydrodynamic simulations, and discuss the potential consequences for the subsequent evolution of massive galaxies at high redshift. Compared with recent models of metal enrichment in high-z AGN hosts, we find that the gas-phase metallicities in our galaxies are lower than in most low-z AGN, but nonetheless solar or even super-solar, suggesting that the ISM we see in these galaxies is very similar to the gas from which massive low

Vortex diode jet

DOEpatents

Houck, Edward D.

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.

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.

Scaled Lunar Module Jet Erosion Experiments

NASA Technical Reports Server (NTRS)

Land, Norman S.; Scholl, Harland F.

1966-01-01

An experimental research program was conducted on the erosion of particulate surfaces by a jet exhaust. These experiments were scaled to represent the lunar module (LM) during landing. A conical cold-gas nozzle simulating the lunar module nozzle was utilized. The investigation was conducted within a large vacuum chamber by using gravel or glass beads as a simulated soil. The effects of thrust, descent speed, nozzle terminal height, particle size on crater size, and visibility during jet erosion were determined.

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.

Atomization of a High Speed Jet

NASA Astrophysics Data System (ADS)

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

2005-11-01

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

A Planar Source of Atmospheric-Pressure Plasma Jet

NASA Astrophysics Data System (ADS)

Zhdanova, O. S.; Kuznetsov, V. S.; Panarin, V. A.; Skakun, V. S.; Sosnin, E. A.; Tarasenko, V. F.

2018-01-01

In a single-barrier discharge with voltage sharpening and low gas consumption (up to 1 L/min), plane atmospheric pressure plasma jets with a width of up to 3 cm and length of up to 4 cm in air are formed in the slit geometry of the discharge zone. The energy, temperature, and spectral characteristics of the obtained jets have been measured. The radiation spectrum contains intense maxima corresponding to vibrational transitions of the second positive system of molecular nitrogen N2 ( C 3Π u → B 3Π g ) and comparatively weak transition lines of the first positive system of the N 2 + ion ( B 2Σ u + → X 2Σ g ). By an example of inactivation of the Staphylococcus aureus culture (strain ATCC 209), it is shown that plasma is a source of chemically active particles providing the inactivation of microorganisms.

Characterization of gas targets for laser produced extreme ultraviolet plasmas with a Hartmann-Shack sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peth, Christian; Kranzusch, Sebastian; Mann, Klaus

2004-10-01

A table top extreme ultraviolet (EUV)-source was developed at Laser-Laboratorium Goettingen for the characterization of optical components and sensoric devices in the wavelength region from 11 to 13 nm. EUV radiation is generated by focusing the beam of a Q-switched Nd:YAG laser into a pulsed xenon gas jet. Since a directed gas jet with a high number density is needed for an optimal performance of the source, conical nozzles with different cone angles were drilled with an excimer laser to produce a supersonic gas jet. The influence of the nozzle geometry on the gas jet was characterized with a Hartmann-Shackmore » wave front sensor. The deformation of a planar wave front after passing the gas jet was analyzed with this sensor, allowing a reconstruction of the gas density distribution. Thus, the gas jet was optimized resulting in an increase of EUV emission by a factor of two and a decrease of the plasma size at the same time.« less

PARSEC-SCALE SHOCKS IN THE KILOPARSEC-SCALE JET OF CENTAURUS A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tingay, S. J.; Lenc, E.

2009-09-15

High angular resolution very long baseline interferometry (VLBI) observations of Centaurus A have been undertaken that allow access to a wide field of view, encompassing both the well-studied parsec-scale jet and the inner part of the kiloparsec-scale jet. The VLBI observations have detected compact regions of synchrotron emission in the kiloparsec-scale jet that coincide with three stationary features identified from previous VLA monitoring observations. Each of these stationary features is associated with strong localized X-ray emission. The VLBI results strengthen arguments made by previous authors suggesting that the stationary features may be the result of stellar objects or gas cloudsmore » traversing the jet flow, intercepting the jet and causing strong shocks. The VLBI data show that the most strongly shocked regions in these features are resolved but have extents no larger than a few pc, reducing the required mass of the typical intercepting object by a factor of {approx}10 relative to previous estimates, making explanations based on high mass-loss stars or low-density gas clouds more plausible.« less

Numerical simulations of turbulent jet ignition and combustion

NASA Astrophysics Data System (ADS)

Validi, Abdoulahad; Irannejad, Abolfazl; Jaberi, Farhad

2013-11-01

The ignition and combustion of a homogeneous lean hydrogen-air mixture by a turbulent jet flow of hot combustion products injected into a colder gas mixture are studied by a high fidelity numerical model. Turbulent jet ignition can be considered as an efficient method for starting and controlling the reaction in homogeneously charged combustion systems used in advanced internal combustion and gas turbine engines. In this work, we study in details the physics of turbulent jet ignition in a fundamental flow configuration. The flow and combustion are modeled with the hybrid large eddy simulation/filtered mass density function (LES/FMDF) approach, in which the filtered form the compressible Navier-Stokes equations are solved with a high-order finite difference scheme for the turbulent velocity and the FMDF transport equations are solved with a Lagrangian stochastic method to obtain the scalar (temperature and species mass fractions) field. The hydrogen oxidation is described by a detailed reaction mechanism with 37 elementary reactions and 9 species.

Cavitating Jet Method and System for Oxygenation of Liquids

NASA Technical Reports Server (NTRS)

Chahine, Georges L.

2012-01-01

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

[Analysis of aromatic hydrocarbons in cracking products of jet fuel by comprehensive two-dimensional gas chromatography-mass spectrometry].

PubMed

Li, Haijing; Zhang, Xiangwen

2017-08-08

As coking precursors, aromatic hydrocarbons have an effect on the cracking stability of fuels. A method for identifying and quantitating aromatics in the supercritical cracking products of jet fuel was established by comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS). The effects of main chromatographic conditions such as initial oven temperature and modulation period on the separation of supercritical cracking products were studied. The method has good separation ability for polycyclic aromatic hydrocarbons (PAH) isomers. A total of 27 aromatics, including monocyclic aromatic hydrocarbons, bicyclic aromatic hydrocarbons, tricyclic aromatic hydrocarbons, tetracyclic aromatic hydrocarbons, etc., were identified based on standard mass spectra, the retention times of standards and literature reports. Moreover, the corresponding quantitative determination was achieved by external standard method of GC×GC-FID. The results showed that the contents of aromatics increased with the increase of gas yield. When gas yield reached 22%, the bicyclic aromatic hydrocarbons began to produce, and their contents increased exponentially with the increase of gas yield. Compared with the traditional GC-MS, the method has better separation and qualitative ability, and can be applied to the separation of complex samples and qualitative and quantitative analyses of cracking products.

Black Hole With Jet (Artist's Concept)

NASA Image and Video Library

2017-11-02

This artist's concept shows a black hole with an accretion disk -- a flat structure of material orbiting the black hole -- and a jet of hot gas, called plasma. Using NASA's NuSTAR space telescope and a fast camera called ULTRACAM on the William Herschel Observatory in La Palma, Spain, scientists have been able to measure the distance that particles in jets travel before they "turn on" and become bright sources of light. This distance is called the "acceleration zone." https://photojournal.jpl.nasa.gov/catalog/PIA22085

Experimental investigation on frequency characteristics of plasma synthetic jets

NASA Astrophysics Data System (ADS)

Zong, Haohua; Kotsonis, Marios

2017-11-01

The performance of a two-electrode plasma synthetic jet actuator (PSJA) is investigated for a wide range of dimensionless actuation frequencies ( f*) using high-speed phase-locked particle imaging velocimetry measurements. The jet-induced velocity fields in the axisymmetric plane are measured during both transient and steady working stages of the PSJA. When f* increases, the jet duration time (Tjet) is reduced, while the peak suction velocity (Us) increases consistently. Three integral parameters including the total expelled gas mass, impulse, and issued mechanical energy also decline considerably with increasing frequency, which is shown to relate to both the reduced cavity density and the decreasing jet duration. Theoretical analysis reveals that the mean cavity density decreases monotonically with the square root of the discharge frequency. The decreasing rate is inversely proportional to a thermal cut-off frequency ( fc, 210 Hz for the current study), which scales with the convective heat transfer coefficient between the actuator cavity walls and the cavity gas, as well as the area of the cavity internal surface. In the time-averaged velocity fields, the jet centreline velocity (U¯ c) exhibits a local maximum in the axial coordinate. The nondimensional maximum centreline velocity reduces with increasing frequency of operation. The jet spreading rate of the plasma synthetic jets (PSJs) decreases from 0.14 to 0.09 with increasing frequency. During the transient working stage of a PSJ, the exit velocity trace elapses 20 successive actuation cycles to stabilize. In contrast to the exit velocity, approximately 130 cycles are needed for the mean cavity density/temperature to reach steady values.

Strong Effects of a Shelfbreak Jet on Microbial Enzyme Activities

NASA Astrophysics Data System (ADS)

Hoarfrost, A.; Balmonte, J. P.; Ziervogel, K.; Ghobrial, S.; Gawarkiewicz, G.; Arnosti, C.

2016-02-01

The activities of extracellular enzymes are critical in initiating microbial cycling of organic carbon, yet the dynamics of heterotrophic enzyme activities in marine environments are still poorly understood. Variations at a given site in rates of activity and the spectrum of organic substrates hydrolyzed may depend upon environmental context. We measured the extracellular enzymatic hydrolysis of 13 high- and low-molecular-weight organic substrates in surface and bottom waters along a closely spaced 4-station transect at 71 W on the North Atlantic continental shelf, in the vicinity of the shelfbreak front. This transect intersects a robust upwelling cell that typically shows high biologic productivity, and is locatable by changes in T/S profiles and chl a concentrations along sharp spatial gradients. At the time of sampling, cold pool waters over the continental shelf were relatively cold, 3.5 Deg. C, compared to 12 Deg. C over the upper continental slope. Satellite thermal imagery indicated that shelf water extended offshore and interacted with a large crest of the Gulf Stream. The surface and bottom waters associated with the upwelling jet were characterized by enzyme activities a factor of 20 more rapid than closer inshore waters, and surface water chl a concentrations that were two to three times higher than the inshore waters. The spectrum of enzyme activities also differed markedly between surface and bottom waters both within the jet and at near-shore stations. Microbial extracellular enzymatic activities were strongly influenced by differences in their environmental context along the continental slope and shelfbreak front. Constraining the factors controlling heterotrophic activity across the diverse marine environment is an important step in understanding microbial controls on carbon cycling.

Toward Active Control of Noise from Hot Supersonic Jets

DTIC Science & Technology

2012-07-24

1.5 heated jet simulated by way of LES. spreading angles of the jet which were determined from prelimi- nary LES computations performed by CRAFT Tech...system allowed time-resolved and high dynamic range measurements to be ob- tained for a heated , supersonic jet. Each component of the system is...independently operated, temporal spacing between frames is variable and can be set in an asynchronous fashion. Such flexibility even allows eight

Transverse jet shear layer instabilities and their control

NASA Astrophysics Data System (ADS)

Karagozian, Ann

2013-11-01

The jet in crossflow, or transverse jet, is a canonical flowfield that has relevance to engineering systems ranging from dilution jets and film cooling for gas turbine engines to thrust vector control and fuel injection in high speed aerospace vehicles to environmental control of effluent from chimney and smokestack plumes. Over the years, our UCLA Energy and Propulsion Research Lab's studies on this 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. A range of different experimental diagnostics have been used to study the jet's upstream shear layer, whereby a transition from convectively unstable behavior at high jet-to-crossflow momentum flux ratios to absolutely unstable flow at low momentum flux and/or density ratios is identified. These differences in shear layer stability characteristics have a profound effect on how one employs external excitation to control jet penetration, spread, and mixing, depending on the flow regime and specific engineering application. These control strategies, and challenges for future research directions, will be identified in this presentation.

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.

Active Control of Supersonic Impinging Jets Using Supersonic Microjets

DTIC Science & Technology

2005-01-01

Impinging Jets using Supersonic Microjets 5b. GRANT NUMBER F49620-03-1-0017 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER Farrukh Alvi 5e. TASK...investigation on the use of microjets for the control of supersonic impinging jets was conducted under this research program. Supersonic impinging...aircraft structures and the landing surfaces. Prior research has shown that microjets , placed around the main jet periphery, are very effective in

Remote sensing of temperature and concentration profiles of a gas jet by coupling infrared emission spectroscopy and LIDAR for characterization of aircraft engine exhaust

NASA Astrophysics Data System (ADS)

Offret, J.-P.; Lebedinsky, J.; Navello, L.; Pina, V.; Serio, B.; Bailly, Y.; Hervé, P.

2015-05-01

Temperature data play an important role in the combustion chamber since it determines both the efficiency and the rate of pollutants emission of engines. Air pollution problem concerns the emissions of gases such as CO, CO2, NO, NO2, SO2 and also aerosols, soot and volatile organic compounds. Flame combustion occurs in hostile environments where temperature and concentration profiles are often not easy to measure. In this study, a temperature and CO2 concentration profiles optical measurement method, suitable for combustion analysis, is discussed and presented. The proposed optical metrology method presents numerous advantages when compared to intrusive methods. The experimental setup comprises a passive radiative emission measurement method combined with an active laser-measurement method. The passive method is based on the use of gas emission spectroscopy. The experimental spectrometer device is coupled with an active method. The active method is used to investigate and correct complex flame profiles. This method similar to a LIDAR (Light Detection And Ranging) device is based on the measurement of Rayleigh scattering of a short laser pulse recorded using a high-speed streak camera. The whole experimental system of this new method is presented. Results obtained on a small-scale turbojet are shown and discussed in order to illustrate the potentials deliver by the sophisticated method. Both temperature and concentration profiles of the gas jet are presented and discussed.

Buoyancy Effects on Flow Transition in Low-Density Inertial Gas Jets

NASA Technical Reports Server (NTRS)

Pasumarthi, Kasyap S.; Agrawal, Ajay K.

2005-01-01

Effects of buoyancy on transition from laminar to turbulent flow are presented for momentum-dominated helium jet injected into ambient air. The buoyancy was varied in a 2.2-sec drop tower facility without affecting the remaining operating parameters. The jet flow in Earth gravity and microgravity was visualized using the rainbow schlieren deflectometry apparatus. Results show significant changes in the flow structure and transition behavior in the absence of buoyancy.

Computational Fluid Dynamics Modeling of Supersonic Coherent Jets for Electric Arc Furnace Steelmaking Process

NASA Astrophysics Data System (ADS)

Alam, Morshed; Naser, Jamal; Brooks, Geoffrey; Fontana, Andrea

2010-12-01

Supersonic coherent gas jets are now used widely in electric arc furnace steelmaking and many other industrial applications to increase the gas-liquid mixing, reaction rates, and energy efficiency of the process. However, there has been limited research on the basic physics of supersonic coherent jets. In the present study, computational fluid dynamics (CFD) simulation of the supersonic jet with and without a shrouding flame at room ambient temperature was carried out and validated against experimental data. The numerical results show that the potential core length of the supersonic oxygen and nitrogen jet with shrouding flame is more than four times and three times longer, respectively, than that without flame shrouding, which is in good agreement with the experimental data. The spreading rate of the supersonic jet decreased dramatically with the use of the shrouding flame compared with a conventional supersonic jet. The present CFD model was used to investigate the characteristics of the supersonic coherent oxygen jet at steelmaking conditions of around 1700 K (1427 °C). The potential core length of the supersonic coherent oxygen jet at steelmaking conditions was 1.4 times longer than that at room ambient temperature.

Numerical simulation of liquid jet impact on a rigid wall

NASA Astrophysics Data System (ADS)

Aganin, A. A.; Guseva, T. S.

2016-11-01

Basic points of a numerical technique for computing high-speed liquid jet impact on a rigid wall are presented. In the technique the flows of the liquid and the surrounding gas are governed by the equations of gas dynamics in the density, velocity, and pressure, which are integrated by the CIP-CUP method on dynamically adaptive grids without explicitly tracking the gas-liquid interface. The efficiency of the technique is demonstrated by the results of computing the problems of impact of the liquid cone and the liquid wedge on a wall in the mode with the shockwave touching the wall by its edge. Numerical solutions of these problems are compared with the analytical solution of the problem of impact of the plane liquid flow on a wall. Applicability of the technique to the problems of the high-speed liquid jet impact on a wall is illustrated by the results of computing a problem of impact of a cylindrical liquid jet with the hemispherical end on a wall covered by a layer of the same liquid.

Laboratory plasma physics experiments using merging supersonic plasma jets

DOE PAGES

Hsu, S. C.; Moser, A. L.; Merritt, E. C.; ...

2015-04-01

We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: n e ≈ n i ~ 10¹⁶ cm⁻³, T e ≈ T i ≈ 1.4 eV, V jet ≈ 30–100 km/s, mean chargemore » $$\\bar{Z}$$ ≈ 1, sonic Mach number M s ≡ V jet/C s > 10, jet diameter = 5 cm, and jet length ≈ 20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.« less

Laboratory plasma physics experiments using merging supersonic plasma jets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, S. C.; Moser, A. L.; Merritt, E. C.

We describe a laboratory plasma physics experiment at Los Alamos National Laboratory that uses two merging supersonic plasma jets formed and launched by pulsed-power-driven railguns. The jets can be formed using any atomic species or mixture available in a compressed-gas bottle and have the following nominal initial parameters at the railgun nozzle exit: n e ≈ n i ~ 10¹⁶ cm⁻³, T e ≈ T i ≈ 1.4 eV, V jet ≈ 30–100 km/s, mean chargemore » $$\\bar{Z}$$ ≈ 1, sonic Mach number M s ≡ V jet/C s > 10, jet diameter = 5 cm, and jet length ≈ 20 cm. Experiments to date have focused on the study of merging-jet dynamics and the shocks that form as a result of the interaction, in both collisional and collisionless regimes with respect to the inter-jet classical ion mean free path, and with and without an applied magnetic field. However, many other studies are also possible, as discussed in this paper.« less

The feed gas composition determines the degree of physical plasma-induced platelet activation for blood coagulation

NASA Astrophysics Data System (ADS)

Bekeschus, Sander; Brüggemeier, Janik; Hackbarth, Christine; Weltmann, Klaus-Dieter; von Woedtke, Thomas; Partecke, Lars-Ivo; van der Linde, Julia

2018-03-01

Cold atmospheric (physical) plasma has long been suggested to be a useful tool for blood coagulation. However, the clinical applicability of this approach has not been addressed sufficiently. We have previously demonstrated the ability of a clinically accepted atmospheric pressure argon plasma jet (kINPen® MED) to coagulate liver incisions in mice with similar performance compared to the gold standard electrocauterization. We could show that plasma-mediated blood coagulation was dependent on platelet activation. In the present work, we extended on this by investigating kINPen®-mediated platelet activation in anticoagulated human donor blood ex vivo. With focus on establishing high-throughput, multi-parametric platelet activation assays and performing argon feed gas parameter studies we achieved the following results: (i) plasma activated platelets in heparinized but not in EDTA-anticoagulated blood; (ii) plasma decreased total platelet counts but increased numbers of microparticles; (iii) plasma elevated the expression of several surface activation markers on platelets (CD62P, CD63, CD69, and CD41/61); (iv) in platelet activation, wet and dry argon plasma outperformed feed gas admixtures with oxygen and/or nitrogen; (v) plasma-mediated platelet activation was accompanied by platelet aggregation. Platelet aggregation is a necessary requirement for blood clot formation. These findings are important to further elucidate molecular details and clinical feasibility of cold physical plasma-mediated blood coagulation.

Final Technical Report summarizing Purdue research activities as part of the DOE JET Topical Collaboration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molnar, Denes

2015-09-01

This report summarizes research activities at Purdue University done as part of the DOE JET Topical Collaboration. These mainly involve calculation of covariant radiative energy loss in the (Djordjevic-)Gyulassy-Levai-Vitev ((D)GLV) framework for relativistic A+A reactions at RHIC and LHC energies using realistic bulk medium evolution with both transverse and longitudinal expansion. The single PDF file provided also includes a report from the entire JET Collaboration.

Dermal exposure to jet fuel suppresses delayed-type hypersensitivity: a critical role for aromatic hydrocarbons.

PubMed

Ramos, Gerardo; Limon-Flores, Alberto Yairh; Ullrich, Stephen E

2007-12-01

Dermal exposure to military (JP-8) and/or commercial (Jet-A) jet fuel suppresses cell-mediated immune reactions. Immune regulatory cytokines and biological modifiers, including platelet activating factor (PAF), prostaglandin E(2), and interleukin-10, have been implicated in the pathway of events leading to immune suppression. It is estimated that approximately 260 different hydrocarbons are found in jet fuel, and the exact identity of the active immunotoxic agent(s) is unknown. The recent availability of synthetic jet fuel (S-8), which is refined from natural gas, and is devoid of aromatic hydrocarbons, made it feasible to design experiments to address this problem. Here we tested the hypothesis that the aromatic hydrocarbons present in jet fuel are responsible for immune suppression. We report that applying S-8 to the skin of mice does not upregulate the expression of epidermal cyclooxygenase-2 (COX-2) nor does it induce immune suppression. Adding back a cocktail of seven of the most prevalent aromatic hydrocarbons found in jet fuel (benzene, toluene, ethylbenzene, xylene, 1,2,4-trimethlybenzene, cyclohexylbenzene, and dimethylnaphthalene) to S-8 upregulated epidermal COX-2 expression and suppressed a delayed-type hypersensitivity (DTH) reaction. Injecting PAF receptor antagonists, or a selective cycloozygenase-2 inhibitor into mice treated with S-8 supplemented with the aromatic cocktail, blocked suppression of DTH, similar to data previously reported using JP-8. These findings identify the aromatic hydrocarbons found in jet fuel as the agents responsible for suppressing DTH, in part by the upregulation of COX-2, and the production of immune regulatory factors and cytokines.

Measurement of the underlying event activity using charged-particle jets in proton-proton collisions at $$\\sqrt{s}$$ = 2.76 TeV

DOE PAGES

Khachatryan, V.

2015-09-21

A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region (|η jet| < 2) and with transverse momentum 1 ≤ p T jet < 100 GeV. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 TeV with the CMS experiment at the LHC. The UE activity is measured as a function of p T jet in terms of the average multiplicity and scalar sum of transverse momenta (p T) of charged particles, with |η| < 2 and p T >more » 0.5 GeV, in the azimuthal region transverse to the highest p T jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. As a result, the measurements are compared to previous results at 0.9 and 7 TeV, and to predictions of several Monte Carlo event generators, providing constraints on the modelling of the UE dynamics« less

Measurement of the underlying event activity using charged-particle jets in proton-proton collisions at √{s}=2.76 TeV

NASA Astrophysics Data System (ADS)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Hartl, C.; Hörmann, N.; Hrubec, J.; Jeitler, M.; Knünz, V.; König, A.; Krammer, M.; Krätschmer, I.; Liko, D.; Matsushita, T.; Mikulec, I.; Rabady, D.; Rahbaran, B.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Strauss, J.; Treberer-Treberspurg, W.; Waltenberger, W.; Wulz, C.-E.; Mossolov, V.; Shumeiko, N.; Suarez Gonzalez, J.; Alderweireldt, S.; Cornelis, T.; de Wolf, E. A.; Janssen, X.; Knutsson, A.; Lauwers, J.; Luyckx, S.; Ochesanu, S.; Rougny, R.; van de Klundert, M.; van Haevermaet, H.; van Mechelen, P.; van Remortel, N.; van Spilbeeck, A.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; Daci, N.; de Bruyn, I.; Deroover, K.; Heracleous, N.; Keaveney, J.; Lowette, S.; Moreels, L.; Olbrechts, A.; Python, Q.; Strom, D.; Tavernier, S.; van Doninck, W.; van Mulders, P.; van Onsem, G. P.; van Parijs, I.; Barria, P.; Caillol, C.; Clerbaux, B.; de Lentdecker, G.; Delannoy, H.; Dobur, D.; Fasanella, G.; Favart, L.; Gay, A. P. R.; Grebenyuk, A.; Lenzi, T.; Léonard, A.; Maerschalk, T.; Mohammadi, A.; Perniè, L.; Randle-Conde, A.; Reis, T.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Wang, J.; Yonamine, R.; Zenoni, F.; Zhang, F.; Beernaert, K.; Benucci, L.; Cimmino, A.; Crucy, S.; Fagot, A.; Garcia, G.; Gul, M.; McCartin, J.; Ocampo Rios, A. A.; Poyraz, D.; Ryckbosch, D.; Salva, S.; Sigamani, M.; Strobbe, N.; Tytgat, M.; van Driessche, W.; Yazgan, E.; Zaganidis, N.; Basegmez, S.; Beluffi, C.; Bondu, O.; Bruno, G.; Castello, R.; Caudron, A.; Ceard, L.; da Silveira, G. G.; Delaere, C.; Favart, D.; Forthomme, L.; Giammanco, A.; Hollar, J.; Jafari, A.; Jez, P.; Komm, M.; Lemaitre, V.; Mertens, A.; Nuttens, C.; Perrini, L.; Pin, A.; Piotrzkowski, K.; Popov, A.; Quertenmont, L.; Selvaggi, M.; Vidal Marono, M.; Beliy, N.; Caebergs, T.; Hammad, G. H.; Aldá Júnior, W. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Dos Reis Martins, T.; Hensel, C.; Mora Herrera, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Custódio, A.; da Costa, E. M.; de Jesus Damiao, D.; de Oliveira Martins, C.; Fonseca de Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Matos Figueiredo, D.; Mundim, L.; Nogima, H.; Prado da Silva, W. L.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; de Souza Santos, A.; Dogra, S.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Moon, C. S.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Genchev, V.; Hadjiiska, R.; Iaydjiev, P.; Marinov, A.; Piperov, S.; Rodozov, M.; Stoykova, S.; Sultanov, G.; Vutova, M.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Cheng, T.; Du, R.; Jiang, C. H.; Plestina, R.; Romeo, F.; Shaheen, S. M.; Tao, J.; Wang, C.; Wang, Z.; Zhang, H.; Asawatangtrakuldee, C.; Ban, Y.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Zou, W.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; Gomez, J. P.; Gomez Moreno, B.; Sanabria, J. C.; Godinovic, N.; Lelas, D.; Polic, D.; Puljak, I.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Kadija, K.; Luetic, J.; Sudic, L.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Bodlak, M.; Finger, M.; Finger, M.; Aly, R.; Aly, S.; Assran, Y.; Elgammal, S.; Ellithi Kamel, A.; Lotfy, A.; Mahmoud, M. A.; Radi, A.; Sayed, A.; Calpas, B.; Kadastik, M.; Murumaa, M.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Pekkanen, J.; Voutilainen, M.; Härkönen, J.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Lehti, S.; Lindén, T.; Luukka, P.; Mäenpää, T.; Peltola, T.; Tuominen, E.; Tuominiemi, J.; Tuovinen, E.; Wendland, L.; Talvitie, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Fabbro, B.; Faure, J. L.; Favaro, C.; Ferri, F.; Ganjour, S.; Givernaud, A.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Locci, E.; Machet, M.; Malcles, J.; Rander, J.; Rosowsky, A.; Titov, M.; Zghiche, A.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Chapon, E.; Charlot, C.; Dahms, T.; Davignon, O.; Filipovic, N.; Florent, A.; Granier de Cassagnac, R.; Lisniak, S.; Mastrolorenzo, L.; Miné, P.; Naranjo, I. N.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Regnard, S.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Agram, J.-L.; Andrea, J.; Aubin, A.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Goetzmann, C.; Le Bihan, A.-C.; Merlin, J. A.; Skovpen, K.; van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Bouvier, E.; Brochet, S.; Carrillo Montoya, C. A.; Chasserat, J.; Chierici, R.; Contardo, D.; Courbon, B.; Depasse, P.; El Mamouni, H.; Fan, J.; Fay, J.; Gascon, S.; Gouzevitch, M.; Ille, B.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Ruiz Alvarez, J. D.; Sabes, D.; Sgandurra, L.; Sordini, V.; Donckt, M. Vander; Verdier, P.; Viret, S.; Xiao, H.; Toriashvili, T.; Bagaturia, I.; Autermann, C.; Beranek, S.; Edelhoff, M.; Feld, L.; Heister, A.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Preuten, M.; Raupach, F.; Sammet, J.; Schael, S.; Schulte, J. F.; Verlage, T.; Weber, H.; Wittmer, B.; Zhukov, V.; Ata, M.; Brodski, M.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Klingebiel, D.; Knutzen, S.; Kreuzer, P.; Merschmeyer, M.; Meyer, A.; Millet, P.; Olschewski, M.; Padeken, K.; Papacz, P.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Sonnenschein, L.; Teyssier, D.; Thüer, S.; Cherepanov, V.; Erdogan, Y.; Flügge, G.; Geenen, H.; Geisler, M.; Hoehle, F.; Kargoll, B.; Kress, T.; Kuessel, Y.; Künsken, A.; Lingemann, J.; Nehrkorn, A.; Nowack, A.; Nugent, I. M.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Asin, I.; Bartosik, N.; Behnke, O.; Behrens, U.; Bell, A. J.; Borras, K.; Burgmeier, A.; Cakir, A.; Calligaris, L.; Campbell, A.; Choudhury, S.; Costanza, F.; Diez Pardos, C.; Dolinska, G.; Dooling, S.; Dorland, T.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Flucke, G.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Gizhko, A.; Gunnellini, P.; Hauk, J.; Hempel, M.; Jung, H.; Kalogeropoulos, A.; Karacheban, O.; Kasemann, M.; Katsas, P.; Kieseler, J.; Kleinwort, C.; Korol, I.; Lange, W.; Leonard, J.; Lipka, K.; Lobanov, A.; Lohmann, W.; Mankel, R.; Marfin, I.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Naumann-Emme, S.; Nayak, A.; Ntomari, E.; Perrey, H.; Pitzl, D.; Placakyte, R.; Raspereza, A.; Ribeiro Cipriano, P. M.; Roland, B.; Sahin, M. Ö.; Salfeld-Nebgen, J.; Saxena, P.; Schoerner-Sadenius, T.; Schröder, M.; Seitz, C.; Spannagel, S.; Trippkewitz, K. D.; Wissing, C.; Blobel, V.; Centis Vignali, M.; Draeger, A. R.; Erfle, J.; Garutti, E.; Goebel, K.; Gonzalez, D.; Görner, M.; Haller, J.; Hoffmann, M.; Höing, R. S.; Junkes, A.; Klanner, R.; Kogler, R.; Lapsien, T.; Lenz, T.; Marchesini, I.; Marconi, D.; Nowatschin, D.; Ott, J.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Pietsch, N.; Poehlsen, J.; Rathjens, D.; Sander, C.; Schettler, H.; Schleper, P.; Schlieckau, E.; Schmidt, A.; Schwandt, J.; Seidel, M.; Sola, V.; Stadie, H.; Steinbrück, G.; Tholen, H.; Troendle, D.; Usai, E.; Vanelderen, L.; Vanhoefer, A.; Akbiyik, M.; Barth, C.; Baus, C.; Berger, J.; Böser, C.; Butz, E.; Chwalek, T.; Colombo, F.; de Boer, W.; Descroix, A.; Dierlamm, A.; Feindt, M.; Frensch, F.; Giffels, M.; Gilbert, A.; Hartmann, F.; Husemann, U.; Kassel, F.; Katkov, I.; Kornmayer, A.; Lobelle Pardo, P.; Mozer, M. U.; Müller, T.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Röcker, S.; Roscher, F.; Simonis, H. J.; Stober, F. M.; Ulrich, R.; Wagner-Kuhr, J.; Wayand, S.; Weiler, T.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Giakoumopoulou, V. A.; Kyriakis, A.; Loukas, D.; Markou, A.; Psallidas, A.; Topsis-Giotis, I.; Agapitos, A.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Tziaferi, E.; Evangelou, I.; Flouris, G.; Foudas, C.; Kokkas, P.; Loukas, N.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Bencze, G.; Hajdu, C.; Hazi, A.; Hidas, P.; Horvath, D.; Sikler, F.; Veszpremi, V.; Vesztergombi, G.; Zsigmond, A. J.; Beni, N.; Czellar, S.; Karancsi, J.; Molnar, J.; Szillasi, Z.; Bartók, M.; Makovec, A.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Mal, P.; Mandal, K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Gupta, R.; Bhawandeep, U.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kumar, R.; Mehta, A.; Mittal, M.; Nishu, N.; Singh, J. B.; Walia, G.; Kumar, Ashok; Kumar, Arun; Bhardwaj, A.; Choudhary, B. C.; Garg, R. B.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Sharma, V.; Banerjee, S.; Bhattacharya, S.; Chatterjee, K.; Dey, S.; Dutta, S.; Jain, Sa.; Jain, Sh.; Khurana, R.; Majumdar, N.; Modak, A.; Mondal, K.; Mukherjee, S.; Mukhopadhyay, S.; Roy, A.; Roy, D.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Abdulsalam, A.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Banerjee, S.; Bhowmik, S.; Chatterjee, R. M.; Dewanjee, R. K.; Dugad, S.; Ganguly, S.; Ghosh, S.; Guchait, M.; Gurtu, A.; Kole, G.; Kumar, S.; Mahakud, B.; Maity, M.; Majumder, G.; Mazumdar, K.; Mitra, S.; Mohanty, G. B.; Parida, B.; Sarkar, T.; Sudhakar, K.; Sur, N.; Sutar, B.; Wickramage, N.; Sharma, S.; Bakhshiansohi, H.; Behnamian, H.; Etesami, S. M.; Fahim, A.; Goldouzian, R.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Caputo, C.; Chhibra, S. S.; Colaleo, A.; Creanza, D.; Cristella, L.; de Filippis, N.; de Palma, M.; Fiore, L.; Iaselli, G.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Benvenuti, A. C.; Bonacorsi, D.; Braibant-Giacomelli, S.; Brigliadori, L.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. 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M.; Lanza, G.; Lista, L.; Meola, S.; Merola, M.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Bellato, M.; Bisello, D.; Carlin, R.; Carvalho Antunes de Oliveira, A.; Checchia, P.; Dall'Osso, M.; Dorigo, T.; Fantinel, S.; Fanzago, F.; Gasparini, F.; Gasparini, U.; Gozzelino, A.; Lacaprara, S.; Margoni, M.; Meneguzzo, A. T.; Pazzini, J.; Pozzobon, N.; Ronchese, P.; Simonetto, F.; Torassa, E.; Tosi, M.; Zanetti, M.; Zotto, P.; Zucchetta, A.; Zumerle, G.; Braghieri, A.; Gabusi, M.; Magnani, A.; Ratti, S. P.; Re, V.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Mantovani, G.; Menichelli, M.; Saha, A.; Santocchia, A.; Spiezia, A.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Bernardini, J.; Boccali, T.; Broccolo, G.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Foà, L.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Martini, L.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Serban, A. T.; Spagnolo, P.; Squillacioti, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; D'Imperio, G.; Del Re, D.; Diemoz, M.; Gelli, S.; Jorda, C.; Longo, E.; Margaroli, F.; Meridiani, P.; Micheli, F.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Traczyk, P.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bellan, R.; Biino, C.; Cartiglia, N.; Costa, M.; Covarelli, R.; Degano, A.; Dellacasa, G.; Demaria, N.; Finco, L.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Musich, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Tamponi, U.; Belforte, S.; Candelise, V.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Gobbo, B.; La Licata, C.; Marone, M.; Schizzi, A.; Umer, T.; Zanetti, A.; Chang, S.; Kropivnitskaya, A.; Nam, S. K.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Kong, D. J.; Lee, S.; Oh, Y. D.; Sakharov, A.; Son, D. C.; Brochero Cifuentes, J. A.; Kim, H.; Kim, T. J.; Ryu, M. S.; Song, S.; Choi, S.; Go, Y.; Gyun, D.; Hong, B.; Jo, M.; Kim, H.; Kim, Y.; Lee, B.; Lee, K.; Lee, K. S.; Lee, S.; Park, S. K.; Roh, Y.; Yoo, H. D.; Choi, M.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Ryu, G.; Choi, Y.; Choi, Y. K.; Goh, J.; Kim, D.; Kwon, E.; Lee, J.; Yu, I.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Komaragiri, J. R.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. 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V.; Vinogradov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Dudko, L.; Ershov, A.; Gribushin, A.; Khein, L.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Myagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Snigirev, A.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Krychkine, V.; Petrov, V.; Ryutin, R.; Sobol, A.; Tourtchanovitch, L.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Ekmedzic, M.; Milosevic, J.; Rekovic, V.; Wang, W. Y.; Alcaraz Maestre, J.; Calvo, E.; Cerrada, M.; Chamizo Llatas, M.; Colino, N.; de La Cruz, B.; Delgado Peris, A.; Domínguez Vázquez, D.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Garcia-Abia, P.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Navarro de Martino, E.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Albajar, C.; de Trocóniz, J. 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V.; Neugebauer, H.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Piparo, D.; Racz, A.; Rolandi, G.; Rovere, M.; Ruan, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Sharma, A.; Silva, P.; Simon, M.; Sphicas, P.; Spiga, D.; Steggemann, J.; Stieger, B.; Stoye, M.; Takahashi, Y.; Treille, D.; Tsirou, A.; Veres, G. I.; Wardle, N.; Wöhri, H. K.; Zagozdzinska, A.; Zeuner, W. D.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Bachmair, F.; Bäni, L.; Bianchini, L.; Buchmann, M. A.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Dünser, M.; Eller, P.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marini, A. C.; Marionneau, M.; Martinez Ruiz Del Arbol, P.; Masciovecchio, M.; Meister, D.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrozzi, L.; Peruzzi, M.; Quittnat, M.; Rossini, M.; Starodumov, A.; Takahashi, M.; Tavolaro, V. R.; Theofilatos, K.; Wallny, R.; Weber, H. A.; Aarrestad, T. K.; Amsler, C.; Canelli, M. F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hinzmann, A.; Hreus, T.; Kilminster, B.; Lange, C.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Ronga, F. J.; Salerno, D.; Taroni, S.; Yang, Y.; Cardaci, M.; Chen, K. H.; Doan, T. H.; Ferro, C.; Konyushikhin, M.; Kuo, C. M.; Lin, W.; Lu, Y. J.; Volpe, R.; Yu, S. S.; Bartek, R.; Chang, P.; Chang, Y. H.; Chang, Y. W.; Chao, Y.; Chen, K. F.; Chen, P. H.; Dietz, C.; Fiori, F.; Grundler, U.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Miñano Moya, M.; Petrakou, E.; Tsai, J. F.; Tzeng, Y. 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R.; Luthra, A.; Malberti, M.; Olmedo Negrete, M.; Shrinivas, A.; Sumowidagdo, S.; Wei, H.; Wimpenny, S.; Branson, J. G.; Cerati, G. B.; Cittolin, S.; D'Agnolo, R. T.; Holzner, A.; Kelley, R.; Klein, D.; Letts, J.; MacNeill, I.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Tu, Y.; Vartak, A.; Wasserbaech, S.; Welke, C.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Barge, D.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Flowers, K.; Franco Sevilla, M.; Geffert, P.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Incandela, J.; Justus, C.; McColl, N.; Mullin, S. D.; Richman, J.; Stuart, D.; Suarez, I.; To, W.; West, C.; Yoo, J.; Anderson, D.; Apresyan, A.; Bornheim, A.; Bunn, J.; Chen, Y.; Duarte, J.; Mott, A.; Newman, H. B.; Pena, C.; Pierini, M.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhu, R. Y.; Azzolini, V.; Calamba, A.; Carlson, B.; Ferguson, T.; Iiyama, Y.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Cumalat, J. P.; Ford, W. T.; Gaz, A.; Jensen, F.; Johnson, A.; Krohn, M.; Mulholland, T.; Nauenberg, U.; Smith, J. G.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chatterjee, A.; Chaves, J.; Chu, J.; Dittmer, S.; Eggert, N.; Mirman, N.; Nicolas Kaufman, G.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Sun, W.; Tan, S. M.; Teo, W. D.; Thom, J.; Thompson, J.; Tucker, J.; Weng, Y.; Wittich, P.; Abdullin, S.; Albrow, M.; Anderson, J.; Apollinari, G.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Cheung, H. W. K.; Chlebana, F.; Cihangir, S.; Elvira, V. D.; Fisk, I.; Freeman, J.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Hanlon, J.; Hare, D.; Harris, R. M.; Hirschauer, J.; Hooberman, B.; Hu, Z.; Jindariani, S.; Johnson, M.; Joshi, U.; Jung, A. W.; Klima, B.; Kreis, B.; Kwan, S.; Lammel, S.; Linacre, J.; Lincoln, D.; Lipton, R.; Liu, T.; Lopes de Sá, R.; Lykken, J.; Maeshima, K.; Marraffino, J. M.; Martinez Outschoorn, V. I.; Maruyama, S.; Mason, D.; McBride, P.; Merkel, P.; Mishra, K.; Mrenna, S.; Nahn, S.; Newman-Holmes, C.; O'Dell, V.; Prokofyev, O.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Whitbeck, A.; Yang, F.; Yin, H.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Carnes, A.; Carver, M.; Curry, D.; Das, S.; di Giovanni, G. P.; Field, R. D.; Fisher, M.; Furic, I. K.; Hugon, J.; Konigsberg, J.; Korytov, A.; Low, J. F.; Ma, P.; Matchev, K.; Mei, H.; Milenovic, P.; Mitselmakher, G.; Muniz, L.; Rank, D.; Shchutska, L.; Snowball, M.; Sperka, D.; Wang, S.; Yelton, J.; Hewamanage, S.; Linn, S.; Markowitz, P.; Martinez, G.; Rodriguez, J. L.; Ackert, A.; Adams, J. R.; Adams, T.; Askew, A.; Bochenek, J.; Diamond, B.; Haas, J.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Khatiwada, A.; Prosper, H.; Veeraraghavan, V.; Weinberg, M.; Bhopatkar, V.; Hohlmann, M.; Kalakhety, H.; Mareskas-Palcek, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Bucinskaite, I.; Cavanaugh, R.; Evdokimov, O.; Gauthier, L.; Gerber, C. E.; Hofman, D. J.; Kurt, P.; O'Brien, C.; Sandoval Gonzalez, I. D.; Silkworth, C.; Turner, P.; Varelas, N.; Wu, Z.; Zakaria, M.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tan, P.; Tiras, E.; Wetzel, J.; Yi, K.; Anderson, I.; Barnett, B. A.; Blumenfeld, B.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Xin, Y.; Baringer, P.; Bean, A.; Benelli, G.; Bruner, C.; Gray, J.; Kenny, R. P.; Majumder, D.; Malek, M.; Murray, M.; Noonan, D.; Sanders, S.; Stringer, R.; Wang, Q.; Wood, J. S.; Chakaberia, I.; Ivanov, A.; Kaadze, K.; Khalil, S.; Makouski, M.; Maravin, Y.; Saini, L. K.; Skhirtladze, N.; Svintradze, I.; Toda, S.; Lange, D.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Gomez, J. A.; Hadley, N. J.; Jabeen, S.; Kellogg, R. G.; Kolberg, T.; Kunkle, J.; Lu, Y.; Mignerey, A. C.; Pedro, K.; Shin, Y. H.; Skuja, A.; Tonjes, M. B.; Tonwar, S. C.; Apyan, A.; Barbieri, R.; Baty, A.; Bierwagen, K.; Brandt, S.; Busza, W.; Cali, I. A.; Demiragli, Z.; Di Matteo, L.; Gomez Ceballos, G.; Goncharov, M.; Gulhan, D.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; McGinn, C.; Niu, X.; Paus, C.; Ralph, D.; Roland, C.; Roland, G.; Stephans, G. S. F.; Sumorok, K.; Varma, M.; Velicanu, D.; Veverka, J.; Wang, J.; Wang, T. W.; Wyslouch, B.; Yang, M.; Zhukova, V.; Dahmes, B.; Finkel, A.; Gude, A.; Hansen, P.; Kalafut, S.; Kao, S. C.; Klapoetke, K.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Tambe, N.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Bose, S.; Claes, D. R.; Dominguez, A.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Keller, J.; Knowlton, D.; Kravchenko, I.; Lazo-Flores, J.; Meier, F.; Monroy, J.; Ratnikov, F.; Siado, J. E.; Snow, G. R.; Alyari, M.; Dolen, J.; George, J.; Godshalk, A.; Iashvili, I.; Kaisen, J.; Kharchilava, A.; Kumar, A.; Rappoccio, S.; Alverson, G.; Barberis, E.; Baumgartel, D.; Chasco, M.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Nash, D.; Orimoto, T.; Teixeira de Lima, R.; Trocino, D.; Wang, R.-J.; Wood, D.; Zhang, J.; Hahn, K. A.; Kubik, A.; Mucia, N.; Odell, N.; Pollack, B.; Pozdnyakov, A.; Schmitt, M.; Stoynev, S.; Sung, K.; Trovato, M.; Velasco, M.; Won, S.; Brinkerhoff, A.; Dev, N.; Hildreth, M.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Lynch, S.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Pearson, T.; Planer, M.; Ruchti, R.; Smith, G.; Valls, N.; Wayne, M.; Wolf, M.; Woodard, A.; Antonelli, L.; Brinson, J.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Hart, A.; Hill, C.; Hughes, R.; Kotov, K.; Ling, T. Y.; Liu, B.; Luo, W.; Puigh, D.; Rodenburg, M.; Winer, B. L.; Wulsin, H. W.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Koay, S. A.; Lujan, P.; Marlow, D.; Medvedeva, T.; Mooney, M.; Olsen, J.; Palmer, C.; Piroué, P.; Quan, X.; Saka, H.; Stickland, D.; Tully, C.; Werner, J. S.; Zuranski, A.; Malik, S.; Barnes, V. E.; Benedetti, D.; Bortoletto, D.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, K.; Kress, M.; Leonardo, N.; Miller, D. H.; Neumeister, N.; Primavera, F.; Radburn-Smith, B. C.; Shi, X.; Shipsey, I.; Silvers, D.; Sun, J.; Svyatkovskiy, A.; Wang, F.; Xie, W.; Xu, L.; Zablocki, J.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Redjimi, R.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Betchart, B.; Bodek, A.; de Barbaro, P.; Demina, R.; Eshaq, Y.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Goldenzweig, P.; Han, J.; Harel, A.; Hindrichs, O.; Khukhunaishvili, A.; Petrillo, G.; Verzetti, M.; Demortier, L.; Arora, S.; Barker, A.; Chou, J. P.; Contreras-Campana, C.; Contreras-Campana, E.; Duggan, D.; Ferencek, D.; Gershtein, Y.; Gray, R.; Halkiadakis, E.; Hidas, D.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Lath, A.; Panwalkar, S.; Park, M.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Foerster, M.; Riley, G.; Rose, K.; Spanier, S.; York, A.; Bouhali, O.; Castaneda Hernandez, A.; Dalchenko, M.; de Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Flanagan, W.; Gilmore, J.; Kamon, T.; Krutelyov, V.; Montalvo, R.; Mueller, R.; Osipenkov, I.; Pakhotin, Y.; Patel, R.; Perloff, A.; Roe, J.; Rose, A.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Cowden, C.; Damgov, J.; Dragoiu, C.; Dudero, P. R.; Faulkner, J.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Undleeb, S.; Volobouev, I.; Appelt, E.; Delannoy, A. G.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Mao, Y.; Melo, A.; Sheldon, P.; Snook, B.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Boutle, S.; Cox, B.; Francis, B.; Goodell, J.; Hirosky, R.; Ledovskoy, A.; Li, H.; Lin, C.; Neu, C.; Wolfe, E.; Wood, J.; Xia, F.; Clarke, C.; Harr, R.; Karchin, P. E.; Kottachchi Kankanamge Don, C.; Lamichhane, P.; Sturdy, J.; Belknap, D. A.; Carlsmith, D.; Cepeda, M.; Christian, A.; Dasu, S.; Dodd, L.; Duric, S.; Friis, E.; Gomber, B.; Hall-Wilton, R.; Herndon, M.; Hervé, A.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Mohapatra, A.; Ojalvo, I.; Perry, T.; Pierro, G. A.; Polese, G.; Ross, I.; Ruggles, T.; Sarangi, T.; Savin, A.; Sharma, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

2015-09-01

A measurement of the underlying event (UE) activity in proton-proton collisions is performed using events with charged-particle jets produced in the central pseudorapidity region (| η jet| < 2) and with transverse momentum 1 ≤ p T jet < 100 GeV. The analysis uses a data sample collected at a centre-of-mass energy of 2.76 TeV with the CMS experiment at the LHC. The UE activity is measured as a function of p T jet in terms of the average multiplicity and scalar sum of transverse momenta ( p T) of charged particles, with | η| < 2 and p T > 0.5 GeV, in the azimuthal region transverse to the highest p T jet direction. By further dividing the transverse region into two regions of smaller and larger activity, various components of the UE activity are separated. The measurements are compared to previous results at 0.9 and 7 TeV, and to predictions of several Monte Carlo event generators, providing constraints on the modelling of the UE dynamics. [Figure not available: see fulltext.

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.

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 jetsmore » 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.« less

Effect of Jet Injection Angle and Number of Jets on Mixing and Emissions From a Reacting Crossflow at Atmospheric Pressure

NASA Technical Reports Server (NTRS)

St.John, D.; Samuelsen, G. S.

2000-01-01

The mixing of air jets into hot, fuel-rich products of a gas turbine primary zone is an important step in staged combustion. Often referred to as "quick quench," the mixing occurs with chemical conversion and substantial heat release. An experiment has been designed to simulate and study this process, and the effect of varying the entry angle (0 deg, 22.5 deg and 45 deg from normal) and number of the air jets (7, 9, and 11) into the main flow, while holding the jet-to-crossflow mass-low ratio, MR, and momentum-flux ratio, J, constant (MR = 2.5;J = 25). The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from orifices equally spaced around the perimeter. A specially designed reactor, operating on propane, presents a uniform mixture to a module containing air jet injection tubes that can be changed to vary orifice geometry. Species concentrations of O2, CO, CO2, NO(x) and HC were obtained one duct diameter upstream (in the rich zone), and primarily one duct radius downstream. From this information, penetration of the jet, the spatial extent of chemical reaction, mixing, and the optimum jet injection angle and number of jets can be deduced.

Asymmetric bubble collapse and jetting in generalized Newtonian fluids

NASA Astrophysics Data System (ADS)

Shukla, Ratnesh K.; Freund, Jonathan B.

2017-11-01

The jetting dynamics of a gas bubble near a rigid wall in a non-Newtonian fluid are investigated using an axisymmetric simulation model. The bubble gas is assumed to be homogeneous, with density and pressure related through a polytropic equation of state. An Eulerian numerical description, based on a sharp interface capturing method for the shear-free bubble-liquid interface and an incompressible Navier-Stokes flow solver for generalized fluids, is developed specifically for this problem. Detailed simulations for a range of rheological parameters in the Carreau model show both the stabilizing and destabilizing non-Newtonian effects on the jet formation and impact. In general, for fixed driving pressure ratio, stand-off distance and reference zero-shear-rate viscosity, shear-thinning and shear-thickening promote and suppress jet formation and impact, respectively. For a sufficiently large high-shear-rate limit viscosity, the jet impact is completely suppressed. Thresholds are also determined for the Carreau power-index and material time constant. The dependence of these threshold rheological parameters on the non-dimensional driving pressure ratio and wall stand-off distance is similarly established. Implications for tissue injury in therapeutic ultrasound will be discussed.

Reduction of gaseous pollutant emissions from gas turbine combustors using hydrogen-enriched jet fuel

NASA Technical Reports Server (NTRS)

Clayton, R. M.

1976-01-01

Recent progress in an evaluation of the applicability of the hydrogen enrichment concept to achieve ultralow gaseous pollutant emission from gas turbine combustion systems is described. The target emission indexes for the program are 1.0 for oxides of nitrogen and carbon monoxide, and 0.5 for unburned hydrocarbons. The basic concept utilizes premixed molecular hydrogen, conventional jet fuel, and air to depress the lean flammability limit of the mixed fuel. This is shown to permit very lean combustion with its low NOx production while simulataneously providing an increased flame stability margin with which to maintain low CO and HC emission. Experimental emission characteristics and selected analytical results are presented for a cylindrical research combustor designed for operation with inlet-air state conditions typical for a 30:1 compression ratio, high bypass ratio, turbofan commercial engine.

Characteristics of transitional and turbulent jet diffusion flames in microgravity

NASA Technical Reports Server (NTRS)

Bahadori, Yousef M.; Small, James F., Jr.; Hegde, Uday G.; Zhou, Liming; Stocker, Dennis P.

1995-01-01

This paper presents the ground-based results obtained to date in preparation of a proposed space experiment to study the role of large-scale structures in microgravity transitional and turbulent gas-jet diffusion flames by investigating the dynamics of vortex/flame interactions and their influence on flame characteristics. The overall objective is to gain an understanding of the fundamental characteristics of transitional and turbulent gas-jet diffusion flames. Understanding of the role of large-scale structures on the characteristics of microgravity transitional and turbulent flames will ultimately lead to improved understanding of normal-gravity turbulent combustion.

Jet in jet in M87

NASA Astrophysics Data System (ADS)

Sob'yanin, Denis Nikolaevich

2017-11-01

New high-resolution Very Long Baseline Interferometer observations of the prominent jet in the M87 radio galaxy show a persistent triple-ridge structure of the transverse 15-GHz profile with a previously unobserved ultra-narrow central ridge. This radio structure can reflect the intrinsic structure of the jet, so that the jet as a whole consists of two embedded coaxial jets. A relativistic magnetohydrodynamic model is considered in which an inner jet is placed inside a hollow outer jet and the electromagnetic fields, pressures and other physical quantities are found. The entire jet is connected to the central engine that plays the role of a unipolar inductor generating voltage between the jets and providing opposite electric currents, and the charge neutrality and current closure together with the electromagnetic fields between the jets can contribute to the jet stabilization. The constant voltage is responsible for the similar widening laws observed for the inner and outer jets. This jet-in-jet structure can indicate simultaneous operation of two different jet-launching mechanisms, one relating to the central supermassive black hole and the other to the surrounding accretion disc. An inferred magnetic field of 80 G at the base is sufficient to provide the observed jet luminosity.

Simulations of Ar gas-puff Z-pinch radiation sources with double shells and central jets on the Z generator

NASA Astrophysics Data System (ADS)

Tangri, V.; Harvey-Thompson, A. J.; Giuliani, J. L.; Thornhill, J. W.; Velikovich, A. L.; Apruzese, J. P.; Ouart, N. D.; Dasgupta, A.; Jones, B.; Jennings, C. A.

2016-10-01

Radiation-magnetohydrodynamic simulations using the non-local thermodynamic equilibrium Mach2-Tabular Collisional-Radiative Equilibrium code in (r, z) geometry are performed for two pairs of recent Ar gas-puff Z-pinch experiments on the refurbished Z generator with an 8 cm diameter nozzle. One pair of shots had an outer-to-inner shell mass ratio of 1:1.6 and a second pair had a ratio of 1:1. In each pair, one of the shots had a central jet. The experimental trends in the Ar K-shell yield and power are reproduced in the calculations. However, the K-shell yield and power are significantly lower than the other three shots for the case of a double-shell puff of 1:1 mass ratio and no central jet configuration. Further simulations of a hypothetical experiment with the same relative density profile of this configuration, but higher total mass, show that the coupled energy from the generator and the K-shell yield can be increased to levels achieved in the other three configurations, but not the K-shell power. Based on various measures of effective plasma radius, the compression in the 1:1 mass ratio and no central jet case is found to be less because the plasma inside the magnetic piston is hotter and of lower density. Because of the reduced density, and the reduced radiation cooling (which is proportional to the square of the density), the core plasma is hotter. Consequently, for the 1:1 outer-to-inner shell mass ratio, the load mass controls the yield and the center jet controls the power.

Comparison of characteristics and downstream uniformity of linear-field and cross-field atmospheric pressure plasma jet array in He

NASA Astrophysics Data System (ADS)

Zhang, Bo; Fang, Zhi; Liu, Feng; Zhou, Renwu; Zhou, Ruoyu

2018-06-01

Using an atmospheric pressure plasma jet array is an effective way for expanding the treatment area of a single jet, and generating arrays with well downstream uniformity is of great interest for its applications. In this paper, a plasma jet array in helium is generated in a linear-field jet array with a ring-ring electrode structure excited by alternating current. The characteristics and downstream uniformity of the array and their dependence on the applied voltage and gas flow rate are investigated through optical, electrical, and Schlieren diagnostics. The results are compared with those of our reported work of a cross-field jet array with a needle-ring electrode structure. The results show that the linear-field jet array can generate relatively large-scale plasma with better uniformity and longer plumes than the cross-field case. The divergences observed in gas channels and the plasma plume trajectories are much less than those of the cross-field one. The deflection angle of lateral plumes is less than 6°, which is independent of the gas flow rate and applied voltage. The maximum downstream plumes of 23 mm can be obtained at 7 kV peak applied voltage and 4 l/min gas flow rate. The better uniformity of linear-field jet arrays is due to the effective suppression of hydrodynamic and electrical interactions among the jets in the arrays with a more uniform electric field distribution. The hydrodynamic interaction induced by the gas heating in the linear-field jet array is less than that of the cross-field one. The more uniform electric field distribution in the linear-field jet arrays can reduce the divergence of the propagation trajectories of the plasma plumes. It will generate less residual charge between the adjacent discharges and thus can reduce the accumulation effect of Coulomb force between the plasma plumes. The reported results can help design controllable and scalable plasma jet arrays with well uniformity for material surface and biomedical treatments.

The Diagnostic Potential of Fe Lines Applied to Protostellar Jets

NASA Astrophysics Data System (ADS)

Giannini, T.; Nisini, B.; Antoniucci, S.; Alcalá, J. M.; Bacciotti, F.; Bonito, R.; Podio, L.; Stelzer, B.; Whelan, E. T.

2013-11-01

We investigate the diagnostic capabilities of iron lines for tracing the physical conditions of shock-excited gas in jets driven by pre-main sequence stars. We have analyzed the 3000-25000 Å, X-shooter spectra of two jets driven by the pre-main sequence stars ESO-Hα 574 and Par-Lup 3-4. Both spectra are very rich in [Fe II] lines over the whole spectral range; in addition, lines from [Fe III] are detected in the ESO-Hα 574 spectrum. Non-local thermal equilibrium codes solving the equations of the statistical equilibrium along with codes for the ionization equilibrium are used to derive the gas excitation conditions of electron temperature and density and fractional ionization. An estimate of the iron gas-phase abundance is provided by comparing the iron lines emissivity with that of neutral oxygen at 6300 Å. The [Fe II] line analysis indicates that the jet driven by ESO-Hα 574 is, on average, colder (T e ~ 9000 K), less dense (n e ~ 2 × 104 cm-3), and more ionized (x e ~ 0.7) than the Par-Lup 3-4 jet (T e ~ 13,000 K, n e ~ 6 × 104 cm-3, x e < 0.4), even if the existence of a higher density component (n e ~ 2 × 105 cm-3) is probed by the [Fe III] and [Fe II] ultra-violet lines. The physical conditions derived from the iron lines are compared with shock models suggesting that the shock at work in ESO-Hα 574 is faster and likely more energetic than the Par-Lup 3-4 shock. This latter feature is confirmed by the high percentage of gas-phase iron measured in ESO-Hα 574 (50%-60% of its solar abundance in comparison with less than 30% in Par-Lup 3-4), which testifies that the ESO-Hα 574 shock is powerful enough to partially destroy the dust present inside the jet. This work demonstrates that a multiline Fe analysis can be effectively used to probe the excitation and ionization conditions of the gas in a jet without any assumption on ionic abundances. The main limitation on the diagnostics resides in the large uncertainties of the atomic data, which, however, can

Receptivity of a Cryogenic Coaxial Gas-Liquid Jet to Acoustic Disturbances

DTIC Science & Technology

2014-06-01

primary diagnostic of the current experimental study involves high-speed backlit imaging. A Phantom v7.10 camera was used to capture images at 10 kHz...Au, H., "Coaxial jets of different mean velocity ratios," Journal of Sound Vibration , Vol. 100, 1985, pp. 211-232. 23. Au, H., and Ko, N., "Coaxial...jets of different mean velocity ratios. II," Journal of Sound Vibration , Vol. 116, 1987, pp. 427-443. 24. Baillot, F., Blaisot, J.-B., Boisdron

The Outer X-ray and Radio Jets in R Aquarii

NASA Technical Reports Server (NTRS)

Kellogg, E.; Anderson, C.; DePasquale, J.; Korreck, K.; Nichols, J.; Sokoloski, J.; Krauss, M.; Pedelty, J.

2007-01-01

The symbiotic star R Aquarii has been known to emit collimated outflow in the form of jets for many years. We report on five years of observations in x-rays and radio using Chandra, VLA and XMM-Newton. We discuss the evolution of the outer thermal jets, including new observations performed in June and October 2005. We see motion of the NE x-ray jet at a projected velocity of about 600 km (sup -1). The SW x-ray jet has almost disappeared between 2000.7 and 2004.0. An XMM grating spectrum of the NE jet confirms the existence of O VII He-like lines, and offers the possibility of doing plasma density diagnostics. We comment on on the physics of cooling in the SW jet and implications for the density of the x-ray emitting gas, the heating mechanism, and mass and kinetic energy in the jets and its implications for the system as a whole. This work was supported by NASA and NSF.

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. 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. The growth rate of initial disturbances for various azimuthal modes has been presented in a wide range of disturbances. PhD Candidate.

Evolution of jets driven by relativistic radiation hydrodynamics as Long and Low Luminosity GRBs

NASA Astrophysics Data System (ADS)

Rivera-Paleo, F. J.; Guzmán, F. S.

2018-06-01

We present numerical simulations of jets modeled with Relativistic Radiation Hydrodynamics (RRH), that evolve across two environments: i) a stratified surrounding medium and ii) a 16TI progenitor model. We consider opacities consistent with various processes of interaction between the fluid and radiation, specifically, free-free, bound-free, bound-bound and electron scattering. We explore various initial conditions, with different radiation energy densities of the beam in hydrodynamical and radiation pressure dominated scenarios, considering only highly-relativistic jets. In order to investigate the impact of the radiation field on the evolution of the jets, we compare our results with purely hydrodynamical jets. Comparing among jets driven by RRH, we find that radiation pressure dominated jets propagate slightly faster than gas pressure dominated ones. Finally, we construct the luminosity Light Curves (LCs) associated with the two cases. The construction of LCs uses the fluxes of the radiation field which is fully coupled to the hydrodynamics equations during the evolution. The main properties of the jets propagating on the stratified surrounding medium are that the LCs show the same order of magnitude as the gamma-ray luminosity of typical Long Gamma-Ray Bursts 1050 - 1054erg/s and the difference between the radiation and gas temperatures is of nearly one order of magnitude. The properties of jets breaking out from the progenitor star model are that the LCs are of the order of magnitude of low-luminosity GRBs 1046 - 1049 erg/s, and in this scenario the difference between the gas and radiation temperature is of four orders of magnitude, which is a case far from thermal equilibrium.

The remarkable AGN jets

NASA Astrophysics Data System (ADS)

Komissarov, Serguei

The jets from active galactic nuclei exhibit stability which seems to be far superior compared to that of terrestrial and laboratory jets. They manage to propagate over distances up to a billion of initial jet radii. Yet this may not be an indication of some exotic physics but mainly a reflection of the specific environment these jets propagate through. The key property of this environment is a rapid decline of density and pressure along the jet, which promotes its rapid expansion. Such an expansion can suppress global instabilities, which require communication across the jet, and hence ensure its survival over huge distances. At kpc scales, some AGN jets do show signs of strong instabilities and even turn into plumes. This could be a result of the flattening of the external pressure distribution in their host galaxies or inside the radio lobes. In this regard, we discuss the possible connection between the stability issue and the Fanaroff-Riley classification of extragalactic radio sources. The observations of AGN jets on sub-kpc scale do not seem to support their supposed lack of causal connectivity. When interpreted using simple kinematic models, they reveal a rather perplexing picture with more questions than answers on the jets dynamics.

Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion

PubMed Central

Ferrer, R.; Barzakh, A.; Bastin, B.; Beerwerth, R.; Block, M.; Creemers, P.; Grawe, H.; de Groote, R.; Delahaye, P.; Fléchard, X.; Franchoo, S.; Fritzsche, S.; Gaffney, L. P.; Ghys, L.; Gins, W.; Granados, C.; Heinke, R.; Hijazi, L.; Huyse, M.; Kron, T.; Kudryavtsev, Yu.; Laatiaoui, M.; Lecesne, N.; Loiselet, M.; Lutton, F.; Moore, I. D.; Martínez, Y.; Mogilevskiy, E.; Naubereit, P.; Piot, J.; Raeder, S.; Rothe, S.; Savajols, H.; Sels, S.; Sonnenschein, V.; Thomas, J-C; Traykov, E.; Van Beveren, C.; Van den Bergh, P.; Van Duppen, P.; Wendt, K.; Zadvornaya, A.

2017-01-01

Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. PMID:28224987

Whither ink jet? Current patent trends

NASA Astrophysics Data System (ADS)

Pond, Stephen F.; Karz, Robert S.

1995-04-01

The status and potential of ink jet technology is discernible in its major technical literature forum: worldwide patents. Most ink jet technical activity is focused in commercial research and development laboratories where proprietary considerations make patents the norm for publication. Currently there are about 2,000 ink jet disclosures issued annually with over 200 enterprises represented. Ink jet patent activity is increasing about 25% per year driven by a rapidly expanding base of products, applications, and revenue. An analysis of the ink jet patent literature reveals a few major themes (i.e. continuous ink jet, piezoelectric drop-on-demand, and thermal ink jet) and numerous minor ones (i.e. electrohydro-dynamic extraction, magnetic drop-on-demand, Hertz continuous, acoustic ink printing). Patents bear witness to transformations in the industry as dominant players of the 1970's have given way to new leaders in the 1990's. They also foretell important commercial developments in ink jet's near term future. When studied in aggregate, the patent record reveals patterns for the industry in general as well as for individual companies. It becomes possible to use the patent data base not only to identify technical approaches and problems for specific firms, but also to track progress and monitor changing strategies. In addition, international filing patterns can provide insights into industry priorities. This paper presents an overview of ink jet technology as revealed by the patent literature. It will include a 25 year perspective, a review of trends over the past five years, and a survey of today's most active companies and their technical approaches. With this analysis, it will be shown that the information inherent in the patent record is more than the sum of its individual disclosures. Indeed, by using it, we can outlook whither goes ink jet.

Polydisperse effects in jet spray flames

NASA Astrophysics Data System (ADS)

Weinberg, Noam; Greenberg, J. Barry

2018-01-01

A laminar jet polydisperse spray diffusion flame is analysed mathematically for the first time using an extension of classical similarity solutions for gaseous jet flames. The analysis enables a comparison to be drawn between conditions for flame stability or flame blow-out for purely gaseous flames and for spray flames. It is found that, in contrast to the Schmidt number criteria relevant to gas flames, droplet size and initial spray polydispersity play a critical role in determining potential flame scenarios. Some qualitative agreement for lift-off height is found when comparing predictions of the theory and sparse independent experimental evidence from the literature.

Subsonic Jet Noise Reduced With Improved Internal Exhaust Gas Mixers

NASA Technical Reports Server (NTRS)

1996-01-01

Aircraft noise pollution is becoming a major environmental concern for the world community. The Federal Aviation Administration (FAA) is responding to this concern by imposing more stringent noise restrictions for aircraft certification then ever before to keep the U.S. industry competitive with the rest of the world. At the NASA Lewis Research Center, attempts are underway to develop noise-reduction technology for newer engines and for retrofitting existing engines so that they are as quiet as (or quieter than) required. Lewis conducted acoustic and Laser Doppler Velocimetry (LDV) tests using Pratt & Whitney's Internal Exhaust Gas Mixers (IEGM). The IEGM's mix the core flow with the fan flow prior to their common exhaust. All tests were conducted in Lewis' Aero-Acoustic Propulsion Laboratory--a semihemispheric dome open to the ambient atmosphere. This was the first time Laser Doppler Velocimetry was used in such a facility at Lewis. Jet exhaust velocity and turbulence and the internal velocity fields were detailed. Far-field acoustics were also measured. Pratt & Whitney provided 1/7th scale model test hardware (a 12-lobe mixer, a 20-lobe mixer, and a splitter) for 1.7 bypass ratio engines, and NASA provided the research engineers, test facility, and test time. The Pratt & Whitney JT8D-200 engine power conditions were used for all tests.

A novel low-jitter plasma-jet triggered gas switch operated at a low working coefficient.

PubMed

Tie, Weihao; Liu, Shanhong; Liu, Xuandong; Zhang, Qiaogen; Pang, Lei; Liu, Longchen

2014-02-01

In this paper, we described the fabrication and testing of a novel plasma-jet triggered gas switch (PJTGS) operated at extremely low working coefficients with excellent triggered jitters. While the structure of the PJTGS is similar to that of a traditional three-electrode field-distortion gas switch, to improve its triggered performance we used a conical micro-plasma-gun with a needle-to-plate spark gap embedded in the trigger electrode. Applying a nanosecond pulse to the trigger electrode caused a spark discharge in the micro-plasma-gun. The electric field drove the discharge plasma to spray into the spark gap of the gas switch, causing fast breakdown. We tested the PJTGS with charging voltages of ±25 kV and a trigger voltage of +80 kV (5 ns rise time and 80 ns full width at half maximum) in two working modes. The PJTGS operated in Mode II had a lower triggered jitter and could be operated over a wider range of working coefficients than in Mode I under the same conditions. At working coefficients higher than 70%, we obtained sub-ns triggered jitters (<0.89 ns) from the PJTGS, at working coefficients lower than 50%, we obtained triggered jitters of 1.6-3.5 ns without no-fires or pre-fires. Even at a working coefficient of 27.4%, the PJTGS could still be triggered reliably with a delay time of 96.1 ns and a triggered jitter of 3.5 ns, respectively.

Review of jet engine emissions

NASA Technical Reports Server (NTRS)

Grobman, J. S.

1972-01-01

A review of the emission characteristics of jet engines is presented. The sources and concentrations of the various constituents in the engine exhaust and the influence of engine operating conditions on emissions are discussed. Cruise emissions to be expected from supersonic engines are compared with emissions from subsonic engines. The basic operating principles of the gas turbine combustor are reviewed together with the effects of combustor operating conditions on emissions. The performance criteria that determine the design of gas turbine combustors are discussed. Combustor design techniques are considered that may be used to reduce emissions.

Hydraulic jet pumping in a remote location

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tjondrodiputro, B.; Gaul, R.B.; Gower, G.H.

1986-12-01

Hydraulic jet pumping equipment was installed in six Sembakung field (N.E. Kalimantan) wells by Atlantic Richfield Indonesia Inc., for Pertamina during 1983, and this article presents the experience acquired in the process of installing and operating this type of artificial-lift equipment in a remote location. Characteristics of the wells and equipment are reviewed, and possible future installations in similar circumstances are discussed. Sembakung oil field, discovered in late 1975, contained 17 wells after complete development. By 1983, some were flowing weakly and several zones were dead, indicating the need for some form of artificial lift. The choice of artificial liftmore » methods was limited by the lack of gas-lift gas, absence of a field-wide power distribution system, unavailability of a rod pumping well servicing unit, and lack of roads in the marshy environment. Thus, hydraulic (free-type) jet pumping was selected as the optimum technique. Jet pumps were installed in six of 17 wells in the field at the end of 1983. Downhole equipment was installed using a heli-rig, and all surface equipment was delivered to location using helicopters. Since startup, some operating problems occurred, but they have all been resolved. Well pumping rates range from 340 to 650 bpd gross, with 0 to 50% BSandW. The jet-pumped wells produced satisfactorily through July 1984, at which time operations were turned over to Pertamina Unit IV at the conclusion of the contractual term.« less

Study of laser-generated debris free x-ray sources produced in a high-density linear Ar, Kr, Xe, Kr/Ar and Xe/Kr/Ar mixtures gas jets by 2 ω, sub-ps LLNL Titan laser

NASA Astrophysics Data System (ADS)

Kantsyrev, V. L.; Schultz, K. A.; Shlyaptseva, V. V.; Safronova, A. S.; Cooper, M. C.; Shrestha, I. K.; Petkov, E. E.; Stafford, A.; Moschella, J. J.; Schmidt-Petersen, M. T.; Butcher, C. J.; Kemp, G. E.; Andrews, S. D.; Fournier, K. B.

2016-10-01

The study of laser-generated debris-free x-ray sources in an underdense plasma produced in a high-density linear gas-puff jet was carried out at the LLNL Titan laser (2 ω, 45 J, sub-ps) with an intensity in the 10 um focal spot of 7 x 1019 W/cm2. A linear nozzle with a fast valve was used for the generation of a clusters/gas jet. X-ray diagnostics for the spectral region of 0.7 - 9 keV include: two spectrometers and pinhole cameras, and 3 groups of fast filtered detectors. Electron beams were measured with the EPPS magnetic spectrometer (>1 MeV) and Faraday cups (>72 keV). Spectralon/spectrometer devices were also used to measure absorption of laser radiation in the jets. New results were obtained on: anisotropic generation of x-rays (laser to x-ray conversion coefficient was >1%) and characteristics of laser-generated electron beams; evolution of x-ray generation with the location of the laser focus in a cluster-gas jet, and observations of a strong x-ray flash in some focusing regimes. Non-LTE kinetic modeling was used to estimate plasma parameters. UNR work supported by the DTRA Basic Research Award # HDTRA1-13-1-0033. Work at LLNL was performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.

Production of bio-jet fuel from microalgae

NASA Astrophysics Data System (ADS)

Elmoraghy, Marian

The increase in petroleum-based aviation fuel consumption, the decrease in petroleum resources, the fluctuation of the crude oil price, the increase in greenhouse gas emission and the need for energy security are motivating the development of an alternate jet fuel. Bio-jet fuel has to be a drop in fuel, technically and economically feasible, environmentally friendly, greener than jet fuel, produced locally and low gallon per Btu. Bic jet fuel has been produced by blending petro-based jet fuel with microalgae biodiesel (Fatty Acid Methyl Ester, or simply FAME). Indoor microalgae growth, lipids extraction and transetrification to biodiesel are energy and fresh water intensive and time consuming. In addition, the quality of the biodiesel product and the physical properties of the bio-jet fuel blends are unknown. This work addressed these challenges. Minimizing the energy requirements and making microalgae growth process greener were accomplished by replacing fluorescent lights with light emitting diodes (LEDs). Reducing fresh water footprint in algae growth was accomplished by waste water use. Microalgae biodiesel production time was reduced using the one-step (in-situ transestrification) process. Yields up to 56.82 mg FAME/g dry algae were obtained. Predicted physical properties of in-situ FAME satisfied European and American standards confirming its quality. Lipid triggering by nitrogen deprivation was accomplished in order to increase the FAME production. Bio-jet fuel freezing points and heating values were measured for different jet fuel to biodiesel blend ratios.

Simulating the interaction of jets with the intracluster medium

NASA Astrophysics Data System (ADS)

Weinberger, Rainer; Ehlert, Kristian; Pfrommer, Christoph; Pakmor, Rüdiger; Springel, Volker

2017-10-01

Jets from supermassive black holes in the centres of galaxy clusters are a potential candidate for moderating gas cooling and subsequent star formation through depositing energy in the intracluster gas. In this work, we simulate the jet-intracluster medium interaction using the moving-mesh magnetohydrodynamics code arepo. Our model injects supersonic, low-density, collimated and magnetized outflows in cluster centres, which are then stopped by the surrounding gas, thermalize and inflate low-density cavities filled with cosmic rays. We perform high-resolution, non-radiative simulations of the lobe creation, expansion and disruption, and find that its dynamical evolution is in qualitative agreement with simulations of idealized low-density cavities that are dominated by a large-scale Rayleigh-Taylor instability. The buoyant rising of the lobe does not create energetically significant small-scale chaotic motion in a volume-filling fashion, but rather a systematic upward motion in the wake of the lobe and a corresponding back-flow antiparallel to it. We find that, overall, 50 per cent of the injected energy ends up in material that is not part of the lobe, and about 25 per cent remains in the inner 100 kpc. We conclude that jet-inflated, buoyantly rising cavities drive systematic gas motions that play an important role in heating the central regions, while mixing of lobe material is subdominant. Encouragingly, the main mechanisms responsible for this energy deposition can be modelled already at resolutions within reach in future, high-resolution cosmological simulations of galaxy clusters.

Overview of the JET results

NASA Astrophysics Data System (ADS)

Romanelli, F.; JET Contributors,

2015-10-01

Since the installation of an ITER-like wall, the JET programme has focused on the consolidation of ITER design choices and the preparation for ITER operation, with a specific emphasis given to the bulk tungsten melt experiment, which has been crucial for the final decision on the material choice for the day-one tungsten divertor in ITER. Integrated scenarios have been progressed with the re-establishment of long-pulse, high-confinement H-modes by optimizing the magnetic configuration and the use of ICRH to avoid tungsten impurity accumulation. Stationary discharges with detached divertor conditions and small edge localized modes have been demonstrated by nitrogen seeding. The differences in confinement and pedestal behaviour before and after the ITER-like wall installation have been better characterized towards the development of high fusion yield scenarios in DT. Post-mortem analyses of the plasma-facing components have confirmed the previously reported low fuel retention obtained by gas balance and shown that the pattern of deposition within the divertor has changed significantly with respect to the JET carbon wall campaigns due to the absence of thermally activated chemical erosion of beryllium in contrast to carbon. Transport to remote areas is almost absent and two orders of magnitude less material is found in the divertor.

Simplified jet-A kinetic mechanism for combustor application

NASA Technical Reports Server (NTRS)

Lee, Chi-Ming; Kundu, Krishna; Ghorashi, Bahman

1993-01-01

Successful modeling of combustion and emissions in gas turbine engine combustors requires an adequate description of the reaction mechanism. For hydrocarbon oxidation, detailed mechanisms are only available for the simplest types of hydrocarbons such as methane, ethane, acetylene, and propane. These detailed mechanisms contain a large number of chemical species participating simultaneously in many elementary kinetic steps. Current computational fluid dynamic (CFD) models must include fuel vaporization, fuel-air mixing, chemical reactions, and complicated boundary geometries. To simulate these conditions a very sophisticated computer model is required, which requires large computer memory capacity and long run times. Therefore, gas turbine combustion modeling has frequently been simplified by using global reaction mechanisms, which can predict only the quantities of interest: heat release rates, flame temperature, and emissions. Jet fuels are wide-boiling-range hydrocarbons with ranges extending through those of gasoline and kerosene. These fuels are chemically complex, often containing more than 300 components. Jet fuel typically can be characterized as containing 70 vol pct paraffin compounds and 25 vol pct aromatic compounds. A five-step Jet-A fuel mechanism which involves pyrolysis and subsequent oxidation of paraffin and aromatic compounds is presented here. This mechanism is verified by comparing with Jet-A fuel ignition delay time experimental data, and species concentrations obtained from flametube experiments. This five-step mechanism appears to be better than the current one- and two-step mechanisms.

Understanding and predicting soot generation in turbulent non-premixed jet flames.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hai; Kook, Sanghoon; Doom, Jeffrey

2010-10-01

This report documents the results of a project funded by DoD's Strategic Environmental Research and Development Program (SERDP) on the science behind development of predictive models for soot emission from gas turbine engines. Measurements of soot formation were performed in laminar flat premixed flames and turbulent non-premixed jet flames at 1 atm pressure and in turbulent liquid spray flames under representative conditions for takeoff in a gas turbine engine. The laminar flames and open jet flames used both ethylene and a prevaporized JP-8 surrogate fuel composed of n-dodecane and m-xylene. The pressurized turbulent jet flame measurements used the JP-8 surrogatemore » fuel and compared its combustion and sooting characteristics to a world-average JP-8 fuel sample. The pressurized jet flame measurements demonstrated that the surrogate was representative of JP-8, with a somewhat higher tendency to soot formation. The premixed flame measurements revealed that flame temperature has a strong impact on the rate of soot nucleation and particle coagulation, but little sensitivity in the overall trends was found with different fuels. An extensive array of non-intrusive optical and laser-based measurements was performed in turbulent non-premixed jet flames established on specially designed piloted burners. Soot concentration data was collected throughout the flames, together with instantaneous images showing the relationship between soot and the OH radical and soot and PAH. A detailed chemical kinetic mechanism for ethylene combustion, including fuel-rich chemistry and benzene formation steps, was compiled, validated, and reduced. The reduced ethylene mechanism was incorporated into a high-fidelity LES code, together with a moment-based soot model and models for thermal radiation, to evaluate the ability of the chemistry and soot models to predict soot formation in the jet diffusion flame. The LES results highlight the importance of including an optically

Nuclear Radio Jet from a Low-luminosity Active Galactic Nucleus in NGC 4258

NASA Astrophysics Data System (ADS)

Doi, Akihiro; Kohno, Kotaro; Nakanishi, Kouichiro; Kameno, Seiji; Inoue, Makoto; Hada, Kazuhiro; Sorai, Kazuo

2013-03-01

The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak radio continuum component at the galactic center. We investigate its radio spectral properties on the basis of our new observations using the Nobeyama Millimeter Array at 100 GHz and archival data from the Very Large Array at 1.7-43 GHz and the James Clerk Maxwell telescope at 347 GHz. The NGC 4258 nuclear component exhibits (1) an intra-month variable and complicated spectral feature at 5-22 GHz and (2) a slightly inverted spectrum at 5-100 GHz (α ~ 0.3; F νvpropνα) in time-averaged flux densities, which are also apparent in the closest LLAGN M81. These similarities between NGC 4258 and M81 in radio spectral natures in addition to previously known core shift in their AU-scale jet structures produce evidence that the same mechanism drives their nuclei. We interpret the observed spectral property as the superposition of emission spectra originating at different locations with frequency-dependent opacity along the nuclear jet. Quantitative differences between NGC 4258 and M81 in terms of jet/counter jet ratio, radio loudness, and degree of core shift can be consistently understood by fairly relativistic speeds (Γ >~ 3) of jets and their quite different inclinations. The picture established from the two closest LLAGNs is useful for understanding the physical origin of unresolved and flat/inverted spectrum radio cores that are prevalently found in LLAGNs, including Sgr A*, with starved supermassive black holes in the present-day universe.

Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions at [Formula: see text] TeV with the ATLAS detector.

PubMed

Aaboud, M; Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Abeloos, B; AbouZeid, O S; Abraham, N L; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adachi, S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Affolder, A A; Agatonovic-Jovin, T; Aguilar-Saavedra, J A; Ahlen, S P; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, T P A; Akimov, A V; Alberghi, G L; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Ali, B; Aliev, M; Alimonti, G; Alison, J; Alkire, S P; Allbrooke, B M M; Allen, B W; Allport, P P; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Alshehri, A A; Alstaty, M; Gonzalez, B Alvarez; Piqueras, D Álvarez; Alviggi, M G; Amadio, B T; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, J K; Anderson, K J; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antel, C; Antonelli, M; Antonov, A; Antrim, D J; Anulli, F; Aoki, M; Aperio Bella, L; Arabidze, G; Arai, Y; Araque, J P; Arce, A T H; Arduh, F A; Arguin, J-F; Argyropoulos, S; Arik, M; Armbruster, A J; Armitage, L J; Arnaez, O; Arnold, H; Arratia, M; Arslan, O; Artamonov, A; Artoni, G; Artz, S; Asai, S; Asbah, N; Ashkenazi, A; Åsman, B; Asquith, L; Assamagan, K; Astalos, R; Atkinson, M; Atlay, N B; Augsten, K; Avolio, G; Axen, B; Ayoub, M K; Azuelos, G; Baak, M A; Baas, A E; Baca, M J; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Bagiacchi, P; Bagnaia, P; Bai, Y; Baines, J T; Bajic, M; Baker, O K; Baldin, E M; Balek, P; Balestri, T; Balli, F; Balunas, W K; Banas, E; Banerjee, Sw; Bannoura, A A E; Barak, L; Barberio, E L; Barberis, D; Barbero, M; Barillari, T; Barisits, M-S; Barklow, T; Barlow, N; Barnes, S L; Barnett, B M; Barnett, R M; Barnovska-Blenessy, Z; Baroncelli, A; Barone, G; Barr, A J; Barranco Navarro, L; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartos, P; Basalaev, A; Bassalat, A; Bates, R L; Batista, S J; Batley, J R; Battaglia, M; Bauce, M; Bauer, F; Bawa, H S; Beacham, J B; Beattie, M D; Beau, T; Beauchemin, P H; Bechtle, P; Beck, H P; Becker, K; Becker, M; Beckingham, M; Becot, C; Beddall, A J; Beddall, A; Bednyakov, V A; Bedognetti, M; Bee, C P; Beemster, L J; Beermann, T A; Begel, M; Behr, J K; Bell, A S; Bella, G; Bellagamba, L; Bellerive, A; Bellomo, M; Belotskiy, K; Beltramello, O; Belyaev, N L; Benary, O; Benchekroun, D; Bender, M; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez, J; Benjamin, D P; Bensinger, J R; Bentvelsen, S; Beresford, L; Beretta, M; Berge, D; Bergeaas Kuutmann, E; Berger, N; Beringer, J; Berlendis, S; Bernard, N R; Bernius, C; Bernlochner, F U; Berry, T; Berta, P; Bertella, C; Bertoli, G; Bertolucci, F; Bertram, I A; Bertsche, C; Bertsche, D; Besjes, G J; Bessidskaia Bylund, O; Bessner, M; Besson, N; Betancourt, C; Bethani, A; Bethke, S; Bevan, A J; Bianchi, R M; Bianco, M; Biebel, O; Biedermann, D; Bielski, R; Biesuz, N V; Biglietti, M; Bilbao De Mendizabal, J; Billoud, T R V; Bilokon, H; Bindi, M; Bingul, A; Bini, C; Biondi, S; Bisanz, T; Bjergaard, D M; Black, C W; Black, J E; Black, K M; Blackburn, D; Blair, R E; Blazek, T; Bloch, I; Blocker, C; Blue, A; Blum, W; Blumenschein, U; Blunier, S; Bobbink, G J; Bobrovnikov, V S; Bocchetta, S S; Bocci, A; Bock, C; Boehler, M; Boerner, D; Bogaerts, J A; Bogavac, D; Bogdanchikov, A G; Bohm, C; Boisvert, V; Bokan, P; Bold, T; Boldyrev, A S; Bomben, M; Bona, M; Boonekamp, M; Borisov, A; Borissov, G; Bortfeldt, J; Bortoletto, D; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Bossio Sola, J D; Boudreau, J; Bouffard, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Boutle, S K; Boveia, A; Boyd, J; Boyko, I R; Bracinik, J; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Breaden Madden, W D; Brendlinger, K; Brennan, A J; Brenner, L; Brenner, R; Bressler, S; Bristow, T M; Britton, D; Britzger, D; Brochu, F M; Brock, I; Brock, R; Brooijmans, G; Brooks, T; Brooks, W K; Brosamer, J; Brost, E; Broughton, J H; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Bruni, A; Bruni, G; Bruni, L S; Brunt, B H; Bruschi, M; Bruscino, N; Bryant, P; Bryngemark, L; Buanes, T; Buat, Q; Buchholz, P; Buckley, A G; Budagov, I A; Buehrer, F; Bugge, M K; Bulekov, O; Bullock, D; Burckhart, H; Burdin, S; Burgard, C D; Burger, A M; Burghgrave, B; Burka, K; Burke, S; Burmeister, I; Burr, J T P; Busato, E; Büscher, D; Büscher, V; Bussey, P; Butler, J M; Buttar, C M; Butterworth, J M; Butti, P; Buttinger, W; Buzatu, A; Buzykaev, A R; Cabrera Urbán, S; Caforio, D; Cairo, V M; Cakir, O; Calace, N; Calafiura, P; Calandri, A; Calderini, G; Calfayan, P; Callea, G; Caloba, L P; Calvente Lopez, S; Calvet, D; Calvet, S; Calvet, T P; Camacho Toro, R; Camarda, S; Camarri, P; Cameron, D; Caminal Armadans, R; Camincher, C; Campana, S; Campanelli, M; Camplani, A; Campoverde, A; Canale, V; Canepa, A; Cano Bret, M; 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Živković, L; Zobernig, G; Zoccoli, A; Nedden, M Zur; Zwalinski, L

2017-01-01

Measurements of jet activity in top-quark pair events produced in proton-proton collisions are presented, using 3.2 fb[Formula: see text] of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge [Formula: see text] pair and two b -tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, [Formula: see text]. The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as a function of the [Formula: see text] threshold for additional jets, and is also presented for different invariant mass regions of the [Formula: see text] system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.

Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions at √s = 13 TeV with the ATLAS detector

DOE PAGES

Aaboud, M; Aad, G; Abbott, B; ...

2017-04-07

Measurements of jet activity in top-quark pair events produced in proton–proton collisions are presented, using 3.2 fb –1 of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge eμ pair and two b-tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, p T. The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as amore » function of the p T threshold for additional jets, and is also presented for different invariant mass regions of the eμbb¯ system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.« less

Measurement of jet activity produced in top-quark events with an electron, a muon and two b-tagged jets in the final state in pp collisions at √s = 13 TeV with the ATLAS detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aaboud, M; Aad, G; Abbott, B

Measurements of jet activity in top-quark pair events produced in proton–proton collisions are presented, using 3.2 fb –1 of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS experiment at the Large Hadron Collider. Events are chosen by requiring an opposite-charge eμ pair and two b-tagged jets in the final state. The normalised differential cross-sections of top-quark pair production are presented as functions of additional-jet multiplicity and transverse momentum, p T. The fraction of signal events that do not contain additional jet activity in a given rapidity region, the gap fraction, is measured as amore » function of the p T threshold for additional jets, and is also presented for different invariant mass regions of the eμbb¯ system. All measurements are corrected for detector effects and presented as particle-level distributions compared to predictions with different theoretical approaches for QCD radiation. While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.« less

Jet Mixing in a Reacting Cylindrical Crossflow

NASA Technical Reports Server (NTRS)

Leong, M. Y.; Samuelsen, G. S.; Holdeman, J. D.

1995-01-01

This paper addresses the mixing of air jets into the hot, fuel-rich products of a gas turbine primary zone. The mixing, as a result, occurs in a reacting environment with chemical conversion and substantial heat release. The geometry is a crossflow confined in a cylindrical duct with side-wall injection of jets issuing from round orifices. A specially designed reactor, operating on propane, presents a uniform mixture without swirl to mixing modules consisting of 8, 9, 10, and 12 holes at a momentum-flux ratio of 57 and a jet-to-mainstream mass-flow ratio of 2.5. Concentrations of O2, CO2, CO, and HC are obtained upstream, downstream, and within the orifice plane. O2 profiles indicate jet penetration while CO2, CO, and HC profiles depict the extent of reaction. Jet penetration is observed to be a function of the number of orifices and is found to affect the mixing in the reacting system. The results demonstrate that one module (the 12-hole) produces near-optimal penetration defined here as a jet penetration closest to the module half-radius, and hence the best uniform mixture at a plane one duct radius from the orifice leading edge.

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

NASA Astrophysics Data System (ADS)

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

2014-11-01

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

Plasma jet takes off.

PubMed Central

Frazer, L

1999-01-01

Thanks to a series of joint research projects by Los Alamos National Laboratory, Beta Squared of Allen, Texas, and the University of California at Los Angeles, there is now a more environmentally sound method for cleaning semiconductor chips that may also be effective in cleaning up chemical, bacterial, and nuclear contaminants. The Atmospheric Pressure Plasma Jet uses a type of ionized gas called plasma to clean up contaminants by binding to them and lifting them away. In contrast to the corrosive acids and chemical solvents traditionally used to clean semiconductor chips, the jet oxidizes contaminants, producing only benign gaseous by-products such as oxygen and carbon dioxide. The new technology is also easy to transport, cleans thoroughly and quickly, and presents no hazards to its operators. PMID:10417375