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Sample records for gas flow sputtering

  1. The influence of pressure and gas flow on size and morphology of titanium oxide nanoparticles synthesized by hollow cathode sputtering

    NASA Astrophysics Data System (ADS)

    Gunnarsson, Rickard; Pilch, Iris; Boyd, Robert D.; Brenning, Nils; Helmersson, Ulf

    2016-07-01

    Titanium oxide nanoparticles have been synthesized via sputtering of a hollow cathode in an argon atmosphere. The influence of pressure and gas flow has been studied. Changing the pressure affects the nanoparticle size, increasing approximately proportional to the pressure squared. The influence of gas flow is dependent on the pressure. In the low pressure regime (107 ≤ p ≤ 143 Pa), the nanoparticle size decreases with increasing gas flow; however, at high pressure (p = 215 Pa), the trend is reversed. For low pressures and high gas flows, it was necessary to add oxygen for the particles to nucleate. There is also a morphological transition of the nanoparticle shape that is dependent on the pressure. Shapes such as faceted, cubic, and cauliflower can be obtained.

  2. On the dependence of structural and sensing properties of sputtered MoO3 thin films on argon gas flow

    NASA Astrophysics Data System (ADS)

    Khojier, K.; Savaloni, H.; Zolghadr, S.

    2014-11-01

    Nitrogen and carbon oxides (CO, NO and NO2), released from combustion facilities and automobiles, are known to be extremely harmful to the human body and also are the main cause of air pollution. Therefore, effective methods to monitor and suppress the carbon and nitrogen oxides have been highly demanded for atmospheric environmental measurements and controls. It is known that molybdenum oxide (MoO3) can be a good semiconductor material for use as a gas sensor in monitoring CO, NO and NO2. In this paper we report the structural characteristics and sensing properties of the sputtered MoO3 thin films as a function of argon gas flow. MoO3 thin films were deposited by DC reactive magnetron sputtering technique on glass substrates at different argon gas flows in the range of 5-20 sccm. X-ray diffraction (XRD) analysis was used for studying crystallographic structure. XRD results showed that all of our films were of polycrystalline structure and of α-MoO3 stable orthorhombic phase. Results also showed that crystallite size increases while compressive nano-strain in the structure of the films decreases with increasing the argon gas flow. Atomic force microscope and the field emission scanning electron microscope studies showed granular structures for all samples, which increased in size consistent with the XRD results, with argon gas flow, while the surface roughness of the films also increased with argon gas flow. Chemical composition study showed optimum reaction between oxygen and molybdenum atoms for films produced at 15 sccm flow of argon gas. The electrical response of samples was measured in the vacuum and the CO environments in the temperature range of 150-350 K. All samples showed Ohmic behavior and the electrical resistances of the films measured in the CO environment were lower than those measured in vacuum. This study showed that the sensing ability of MoO3 for CO improves with increasing the argon gas flow.

  3. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    PubMed

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH).

  4. Influence of the N2 gas flow on optical and structural properties of reactively sputtered ZrN films

    NASA Astrophysics Data System (ADS)

    Schleussner, S.; Törndahl, T.; Edoff, M.

    2008-03-01

    We present optical and structural properties of reactively sputtered zirconium nitride (ZrN) films for application as back reflectors in Cu(In,Ga)Se2 solar cells with sub-micrometer absorbers. In this study, ZrN films were deposited by reactive DC sputtering on blank, Mo-coated and Zr-coated soda-lime glass at two different process pressures and various ratios of nitrogen mixed in the argon working gas. When characterised by x-ray diffraction (XRD), the majority of the films were found to consist of single-phase cubic ZrN. All peaks corresponding to the ZrN phase were present in the diffractograms with intensities similar to those obtained from bulk ZrN, indicating that the films were randomly oriented. No significant differences were found between films grown on different substrate types. Films sputtered with lower nitrogen partial pressures displayed a spectral optical reflectance similar to metallic Zr, while films prepared with higher N2 flows showed the pronounced Drude-like reflectance characteristic of the nitride. The best ZrN films were achieved with a process pressure of 2.5 mTorr and a N2/(Ar+N2) flow ratio of 26.5%. At a wavelength of 800 nm the reflectance of these reached 85%, as compared to a typical value of 58% in the case of molybdenum.

  5. Photocatalytic Properties of TiO2 Thin Films Modified with Ag and Pt Nanoparticles Deposited by Gas Flow Sputtering.

    PubMed

    Maicu, M; Glöss, D; Frach, Peter; Hecker, D; Gerlach, G; Córdoba, José M

    2015-09-01

    In this work, a gas flow sputtering (GFS) process which allows the production and deposition of metal nanoparticles (NPs) in a vacuum environment is described. Aim of the study is to prove the potential of this technology for the fabrication of new TiO2 films with enhanced photocatalytic properties. For this purpose, Ag and Pt NPs have been produced and deposited on photocatalytic float glass coated with TiO2 thin films by magnetron sputtering. The influence of the process parameters and of the metal amount on the final properties of the particles (quantity, size, size distribution, oxidation state etc.,) was widely investigated. Moreover, the effect of the NPs on the photocatalytic activity of the resulting materials was evaluated for the case of the decomposition of stearic acid (SA) during UV-A irradiation. The reduction of the water contact angle (WCA) during the irradiation period was measured in order to test the photo-induced super-hydrophilicity (PSH). PMID:26716202

  6. High rate deposition of photocatalytic TiO{sub 2} films with high activity by hollow cathode gas-flow sputtering method

    SciTech Connect

    Kubo, Yoshiyuki; Iwabuchi, Yoshinori; Yoshikawa, Masato; Sato, Yasushi; Shigesato, Yuzo

    2008-07-15

    Photocatalytic TiO{sub 2} films were deposited by a hollow cathode gas-flow sputtering method using two Ti metal targets mounted parallel to each other. The Ar and O{sub 2} flow rates were 3000 and 0-50 SCCM (SCCM denotes cubic centimeter per minute at STP), respectively, and total gas pressure during the deposition was maintained at 45 Pa. The highest deposition rate for the photocatalytic TiO{sub 2} films was 162 nm/min at 30 SCCM of O{sub 2} flow. The as-deposited films and postannealed films, annealed in air at 300 deg. C for 1 h, were used to carry out photocatalytic decomposition of acetaldehyde (CH{sub 3}CHO). In particular, the postannealed films showed extremely high photocatalytic activity compared to the photocatalytic activity of films deposited by conventional reactive sputtering.

  7. Visible-light active thin-film WO3 photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    NASA Astrophysics Data System (ADS)

    Oka, Nobuto; Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Iwabuchi, Yoshinori; Kotsubo, Hidefumi; Shigesato, Yuzo

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO3 films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO3 films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH3CHO under visible light irradiation. The decomposition time for 60 ppm of CH3CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO3 films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH3CHO.

  8. Visible-light active thin-film WO{sub 3} photocatalyst with controlled high-rate deposition by low-damage reactive-gas-flow sputtering

    SciTech Connect

    Oka, Nobuto Murata, Akiyo; Nakamura, Shin-ichi; Jia, Junjun; Shigesato, Yuzo; Iwabuchi, Yoshinori; Kotsubo, Hidefumi

    2015-10-01

    A process based on reactive gas flow sputtering (GFS) for depositing visible-light active photocatalytic WO{sub 3} films at high deposition rates and with high film quality was successfully demonstrated. The deposition rate for this process was over 10 times higher than that achieved by the conventional sputtering process and the process was highly stable. Furthermore, Pt nanoparticle-loaded WO{sub 3} films deposited by the GFS process exhibited much higher photocatalytic activity than those deposited by conventional sputtering, where the photocatalytic activity was evaluated by the extent of decomposition of CH{sub 3}CHO under visible light irradiation. The decomposition time for 60 ppm of CH{sub 3}CHO was 7.5 times more rapid on the films deposited by the GFS process than on the films deposited by the conventional process. During GFS deposition, there are no high-energy particles bombarding the growing film surface, whereas the bombardment of the surface with high-energy particles is a key feature of conventional sputtering. Hence, the WO{sub 3} films deposited by GFS should be of higher quality, with fewer structural defects, which would lead to a decrease in the number of centers for electron-hole recombination and to the efficient use of photogenerated holes for the decomposition of CH{sub 3}CHO.

  9. Reactive sputtering of titanium in Ar/CH4 gas mixture: Target poisoning and film characteristics

    SciTech Connect

    Fouad, O.A.; Rumaiz, A.; Shah, S.

    2009-03-01

    Reactive sputtering of titanium target in the presence of Ar/CH{sub 4} gas mixture has been investigated. With the addition of methane gas to above 1.5% of the process gas a transition from the metallic sputtering mode to the poison mode was observed as indicated by the change in cathode current. As the methane gas flow concentration increased up to 10%, the target was gradually poisoned. The hysteresis in the cathode current could be plotted by first increasing and then subsequently decreasing the methane concentration. X-ray diffraction and X-ray photoelectron spectroscopy analyses of the deposited films confirmed the formation of carbide phases and the transition of the process from the metallic to compound sputtering mode as the methane concentration in the sputtering gas is increased. The paper discusses a sputtering model that gives a rational explanation of the target poisoning phenomenon and shows an agreement between the experimental observations and calculated results.

  10. In vitro flow measurements in ion sputtered hydrocephalus shunts

    NASA Technical Reports Server (NTRS)

    Cho, Y. I.; Back, L. H.

    1989-01-01

    This paper describes an experimental procedure for accurate measurements of the pressure-drop/flow rate relationship in hydrocephalus shunts. Using a fish-hook arrangement, small flow rates in a perforated ion-sputtered Teflon microtubule were measured in vitro in a pressured system and were correlated with pressure in the system. Results indicate that appropriate drainage rates could be obtained in the physiological range for hydrocephalus shunts.

  11. Using sputter coated glass to stabilize microstrip gas chambers

    DOEpatents

    Gong, Wen G.

    1997-01-01

    By sputter coating a thin-layer of low-resistive, electronically-conductive glass on various substrates (including quartz and ceramics, thin-film Pestov glass), microstrip gas chambers (MSGC) of high gain stability, low leakage current, and a high rate capability can be fabricated. This design can make the choice of substrate less important, save the cost of ion-implantation, and use less glass material.

  12. A pulsed DC gas flow hollow cathode

    NASA Astrophysics Data System (ADS)

    Paduraru, Cristian

    A new gas flow hollow cathode discharge source (GFHC) has been developed, characterized, and applied to thin film deposition by sputtering and low-temperature PECVD. Non-reactive and reactive sputtering processes were investigated using copper and aluminum targets, respectively. For the first time, pulsed DC power was applied to a GFHC in order to avoid arcing caused by electrode surface contamination, and to stabilize the discharge in general. The electrical characteristics of the source, the parameters of the remote plasma and its optical emission, were studied and compared to those of a DC powered GFHC. We determined the electrical characteristics of the plasma, including the temporal behavior of the current and voltage under various conditions of pressure and inert gas flow through the cathode. The transition from a glow discharge mode to the hollow cathode mode was studied in an effort to determine the operating range of the GFHC. A capacitive current was discovered at the beginning of the on-time. The properties of the remote plasma were investigated using averaged and time-resolved Langmuir probe and optical emission measurements. The distribution of the remote plasma density resembles the gas flow velocity distribution through the cathode. Plasma processes during off time (decaying plasma) and on-time (plasma reestablishment) were studied and compared to those in pulsed DC magnetron and high power inductively coupled glow discharges. The dependence of the deposition rate, resistivity and thickness distribution of copper films dependence on pulse parameters, power, inert gas flow through the cathode and pressure have been studied. The thin film thickness distribution is governed by the distribution of the gas flow velocity, which can be calculated using laminar flow gas dynamics. In a pulsed DC GFHC system, the inert gas flow through the cathode prevents the penetration of the reactive gas from the chamber into the cathode. A special reactive gas delivery

  13. Paraelectric gas flow accelerator

    NASA Technical Reports Server (NTRS)

    Sherman, Daniel M. (Inventor); Wilkinson, Stephen P. (Inventor); Roth, J. Reece (Inventor)

    2001-01-01

    A substrate is configured with first and second sets of electrodes, where the second set of electrodes is positioned asymmetrically between the first set of electrodes. When a RF voltage is applied to the electrodes sufficient to generate a discharge plasma (e.g., a one-atmosphere uniform glow discharge plasma) in the gas adjacent to the substrate, the asymmetry in the electrode configuration results in force being applied to the active species in the plasma and in turn to the neutral background gas. Depending on the relative orientation of the electrodes to the gas, the present invention can be used to accelerate or decelerate the gas. The present invention has many potential applications, including increasing or decreasing aerodynamic drag or turbulence, and controlling the flow of active and/or neutral species for such uses as flow separation, altering heat flow, plasma cleaning, sterilization, deposition, etching, or alteration in wettability, printability, and/or adhesion.

  14. Estimation of sputtering rate by bombardment with argon gas ions

    NASA Astrophysics Data System (ADS)

    Okajima, Yoshiaki

    1980-01-01

    The sputtering rates of single-crystal Si and polycrystalline Ag, Cu, Ni, Ti, and Al were measured. These target materials were bombarded with argon ions accelerated at 10 kV. The sputtered depth after a given interval of bombardment was greatest for Ag, and decreased for the other materials in the following order: Cu, Ni, Ti, Si, and Al. The difference in the sputtering rates of these target materials was investigated on the basis of their binding energies, and the following expression for sputtering rate was obtained experimentally, Sr=K (I/D)(M/Ec)k, where Sr is the sputtering rate, I is the current density of incident argon ions, and D, M, and Ec are the atomic concentration, mass number, and cohesive energy of a target material, respectively. K and k are constants. Sputtering yield (Sy) can be written Sy=K' (M/Ec)k. The result was compared with experimental data of many target materials already reported. These results were used to estimate the sputtered depth after a given interval in the practical analyses using ion bombardment.

  15. Effect of gas ratio on tribological properties of sputter deposited TiN coatings

    NASA Astrophysics Data System (ADS)

    Chavda, Mahesh R.; Chauhan, Kamlesh V.; Rawal, Sushant K.

    2016-05-01

    Titanium nitride (TiN) coatings were deposited on Si, corning glass, pins of mild steel (MS, ϕ3mm), aluminium (Al, ϕ4mm) and brass (ϕ6mm) substratesby DC magnetron sputtering. The argon and nitrogen (Ar:N2)gas ratio was precisely controlled by Mass Flow Controller (MFC) and was varied systematically at diffract values of 10:10,12:08, 16:04 and 18:02sccm. The structural properties of TiN coatings were characterized by X-ray diffraction (XRD) and its surface topography was studied using field emission scanning electron microscopy (FE-SEM). The tribological properties of TiN coatings were investigated using pin-on-disc tribometer.

  16. Gas flow meter and method for measuring gas flow rate

    DOEpatents

    Robertson, Eric P.

    2006-08-01

    A gas flow rate meter includes an upstream line and two chambers having substantially equal, fixed volumes. An adjustable valve may direct the gas flow through the upstream line to either of the two chambers. A pressure monitoring device may be configured to prompt valve adjustments, directing the gas flow to an alternate chamber each time a pre-set pressure in the upstream line is reached. A method of measuring the gas flow rate measures the time required for the pressure in the upstream line to reach the pre-set pressure. The volume of the chamber and upstream line are known and fixed, thus the time required for the increase in pressure may be used to determine the flow rate of the gas. Another method of measuring the gas flow rate uses two pressure measurements of a fixed volume, taken at different times, to determine the flow rate of the gas.

  17. Huge increase in gas phase nanoparticle generation by pulsed direct current sputtering in a reactive gas admixture

    NASA Astrophysics Data System (ADS)

    Polonskyi, Oleksandr; Peter, Tilo; Mohammad Ahadi, Amir; Hinz, Alexander; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

    2013-07-01

    Using reactive DC sputtering in a gas aggregation cluster source, we show that pulsed discharge gives rise to a huge increase in deposition rate of nanoparticles by more than one order of magnitude compared to continuous operation. We suggest that this effect is caused by an equilibrium between slight target oxidation (during "time-off") and subsequent sputtering of Ti oxides (sub-oxides) at "time-on" with high power impulse.

  18. On the gas dynamics of laser-pulse sputtering of polymethylmethacrylate

    NASA Astrophysics Data System (ADS)

    Braren, Bodil; Casey, Kelly G.; Kelly, Roger

    1991-06-01

    The laser-pulse sputtering of polymers should have two limiting cases. In the one there is ongoing release of particles from the target surface, the particles then form a Knudsen layer (KL), and there is finally an unsteady adiabatic expansion (UAE) ('effusion' model). In the other limit, bond-breakage occurs rapidly over a characteristic depth and the resulting gaslike particles then flow out directly in a UAE without a formal KL ('outflow' model). To test these idealized gas-dynamic descriptions, we discuss experiments in which ˜ 20 ns excimer laser pulses are incident on polymethylmethacrylate in air at 193 or 248 nm and the release process is photographed with a ˜ 1 ns probe pulse. The results not only give explicit support to the gas-dynamic description of the problem, but also indicate that the KL-UAE model is more appropriate. For example, only this model accommodates the observation that the release process continues for ˜ 6 μs, which is ˜ 500 times the laser pulse length.

  19. Gas dynamics of the pulsed emission of a perfect gas with applications to laser sputtering and to nozzle expansion

    NASA Astrophysics Data System (ADS)

    Kelly, Roger

    1992-07-01

    An analytical 1D continuum solution is introduced describing particles released from a target by laser-pulse bombardment that form a Knudsen layer (KL) and pass into unsteady adiabatic expansion (UAE). In the present 'effusion' model the particles are not subject to recondensing at the target surface if the release pulse terminates, and the KL is expressed as a boundary condition. Solutions are given for the dynamics during the release pulse and the end of the pulse to determine changes in the boundary conditions and flow patterns. The flow equations by Knight (1982) and experimental photographic data are compared to the conclusions based on the analysis. The analytical conclusions are shown to agree with the available data regarding: (1) the laser-pulse sputtering of Al; (2) combined KL-UAE in the surface release from PMMA sputtering; and (3) the angular effects in the sputtering of CdS.

  20. High gas flow alpha detector

    DOEpatents

    Bolton, Richard D.; Bounds, John A.; Rawool-Sullivan, Mohini W.

    1996-01-01

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors.

  1. High gas flow alpha detector

    DOEpatents

    Bolton, R.D.; Bounds, J.A.; Rawool-Sullivan, M.W.

    1996-05-07

    An alpha detector for application in areas of high velocity gas flows, such as smokestacks and air vents. A plurality of spaced apart signal collectors are placed inside an enclosure, which would include smokestacks and air vents, in sufficient numbers to substantially span said enclosure so that gas ions generated within the gas flow are electrostatically captured by the signal collector means. Electrometer means and a voltage source are connected to the signal collectors to generate an electrical field between adjacent signal collectors, and to indicate a current produced through collection of the gas ions by the signal collectors. 4 figs.

  2. The Fabrication of Flow Field Plates for Direct Methanol Fuel Cell Using Lithography and Radio Frequency Sputtering.

    PubMed

    Chang, Ho; Kao, Mu-Jung; Chen, Chih-Hao; Cho, Kun-Ching; Hsu, Chun-Yao; Chen, Zhi-Lun

    2015-08-01

    This study uses lithography to etch flow fields on a single side of a printed circuit board (PCB) and combines a flow field plate with a collector plate to make innovative anode flow field plates and cathode flow field plates for a direct methanol fuel cell (DMFC). TiO2 thin film is also sputtered on the anode flow field plate using radio frequency (RF) sputtering. The experimental results show that the prepared DMFC has a better maximum power density of 11.928 mW/cm2. Furthermore, when a TiO2 thin film is sputtered on the flow field plate of the assembled DMFC, the maximum power density is 14.426 mW/cm2, which is actually 21% more than that for a DMFC with no TiO2 thin film coated on the flow field plate.

  3. Angle dependence of argon gas cluster sputtering yields for organic materials.

    PubMed

    Seah, M P; Spencer, S J; Shard, A G

    2015-02-19

    The first angle-dependent measurements of the sputtering yield of an organic material using argon gas cluster ions under a wide range of conditions are reported in order to develop an analytical description of the behavior important for the development of the application of secondary ion mass spectrometry to organic and biological systems. Data are presented for Irganox 1010 using argon gas cluster ion beams of 5 and 10 keV energy, E, with cluster sizes, n, from 1000 to 5000. The measurements are conducted in an X-ray photoelectron spectrometer for a range of angles from 0 to 80° from the surface normal. The results support the Universal Equation for argon gas cluster sputtering yields with the angle dependence incorporated into the equation via a simple angle dependence of the parameter A. This explains how and why the angular dependence of the sputtering yield changes significantly with increasing E/n. These results are also accurately confirmed using the published measurements for polystyrene by Rading et al.

  4. Solid-gas critical flow

    SciTech Connect

    Gidaspow, D.; Syamlal, M.

    1985-01-01

    Maximum solid-gas transport rates have been computed using several hydrodynamic models. In the limit of zero gas density, the critical velocity equals the square root of a compressibility modulus of the powder divided by its density. Compressibility waves move with this velocity through the powder. Part II of this paper deals with homogeneous critical powder flow for which a useful expression for maximum flow has been derived and compared to an experiment from the literature.

  5. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  6. Magnetron sputtering of copper on thermosensitive polymer materials of the gas centrifuge rotors

    NASA Astrophysics Data System (ADS)

    Borisevich, V.; Senchenkov, S.; Titov, D.

    2016-09-01

    Magnetron sputtering is the well-known and widely-used deposition technique for coating versatile high-quality and well-adhered films. However, the technology has some limitations, caused by high temperatures on the coating surface. The paper is devoted to the experimental development of a process of magnetron sputtering of copper on a surface coated with a thermosensitive polymer made of carbon fiber with epoxide binder. This process is applied for balancing a rotor of a gas centrifuge for isotope separation. The optimum operating parameters of the process are found and discussed. They were in quantitative agreement with data obtained by means of non-stationary modeling based on a global description of plasma in the typical geometry of the magnetron discharges obtained in independent research. The structure of the resulting layer is investigated.

  7. Gas flow in barred potentials

    NASA Astrophysics Data System (ADS)

    Sormani, Mattia C.; Binney, James; Magorrian, John

    2015-05-01

    We use a Cartesian grid to simulate the flow of gas in a barred Galactic potential and investigate the effects of varying the sound speed in the gas and the resolution of the grid. For all sound speeds and resolutions, streamlines closely follow closed orbits at large and small radii. At intermediate radii shocks arise and the streamlines shift between two families of closed orbits. The point at which the shocks appear and the streamlines shift between orbit families depends strongly on sound speed and resolution. For sufficiently large values of these two parameters, the transfer happens at the cusped orbit as hypothesized by Binney et al. over two decades ago. For sufficiently high resolutions, the flow downstream of the shocks becomes unsteady. If this unsteadiness is physical, as appears to be the case, it provides a promising explanation for the asymmetry in the observed distribution of CO.

  8. Sputter process with time-variant reactive gas mixture for the deposition of optical multilayer and gradient layer systems

    NASA Astrophysics Data System (ADS)

    Bartzsch, H.; Weber, J.; Lau, K.; Glöß, D.; Frach, P.

    2008-09-01

    Magnetron sputtering of a silicon target in a time-variant mixture of the reactive gases oxygen and nitrogen allows the deposition of optical multilayer and gradient layer systems of silicon oxinitride at one stationary sputtering station. In this paper the processes within the sputter discharge and the properties of the growing film during the change of the reactive gas composition are investigated using optical in-situ monitoring, optical plasma emission spectroscopy and plasma impedance monitoring. A time delay between the change to the reactive gas composition and the resulting change to the film composition was observed. The time delay is longer for the transition from oxide to nitride deposition then vice versa. This asymmetry is attributed to the different affinity of nitrogen and oxygen to the silicon target. Examples of deposited antireflective coatings as well as rugate filters based on silicon oxinitride multilayer and gradient layer designs are given.

  9. Laser cross-flow gas system

    DOEpatents

    Duncan, David B.

    1992-01-01

    A method and laser apparatus are disclosed which provide for a cross-flow of gas near one end of a laser discharge tube. The cross-flow of gas causes a concentration gradient which affects diffusion of contaminants in the discharge tube towards the cross-flow of the gas, which contaminants are then withdrawn from the discharge tube.

  10. Net sputtering rate due to hot ions in a Ne-Xe discharge gas bombarding an MgO layer

    SciTech Connect

    Ho, S.; Tamakoshi, T.; Ikeda, M.; Mikami, Y.; Suzuki, K.

    2011-04-15

    An analytical method is developed for determining net sputtering rate for an MgO layer under hot ions with low energy (<100 eV) in a neon-xenon discharge gas at near-atmospheric pressure. The primary sputtering rate is analyzed according to spatial and energy distributions of the hot ions with average energy, E{sup h}{sub i}, above a threshold energy of sputtering, E{sub th,i}, multiplied by a yield coefficient. The threshold energy of sputtering is determined from dissociation energy required to remove an atom from MgO surface multiplied by an energy-transfer coefficient. The re-deposition rate of the sputtered atoms is calculated by a diffusion simulation using a hybridized probabilistic and analytical method. These calculation methods are combined to analyze the net sputtering rate. Maximum net sputtering rate due to the hot neon ions increases above the partial pressure of 4% xenon as E{sup h}{sub Ne} becomes higher and decreases near the partial pressure of 20% xenon as ion flux of neon decreases. The dependence due to the hot neon ions on partial pressure and applied voltage agrees well with experimental results, but the dependence due to the hot xenon ions deviates considerably. This result shows that the net sputtering rate is dominated by the hot neon ions. Maximum E{sup h}{sub Ne} (E{sup h}{sub Ne,max} = 5.3 - 10.3 eV) is lower than E{sub th,Ne} (19.5 eV) for the MgO layer; therefore, weak sputtering due to the hot neon ions takes place. One hot neon ion sputters each magnesium and each oxygen atom on the surface and distorts around a vacancy. The ratio of the maximum net sputtering rate is approximately determined by number of the ions at E{sup h}{sub i,max} multiplied by an exponential factor of -E{sub th,i}/E{sup h}{sub i,max}.

  11. Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Pereira, André L. J.; Lisboa Filho, Paulo N.; Acuña, Javier; Brandt, Iuri S.; Pasa, André A.; Zanatta, Antonio R.; Vilcarromero, Johnny; Beltrán, Armando; Dias da Silva, José H.

    2012-06-01

    Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O2 gas supply is periodically interrupted rather than by a decrease of the partial O2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 × 102 cm-1 to more than 4 × 103 cm-1 as a result of the gas flow discontinuity. A red-shift of ˜0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40 nm. Moreover, the interruptions of the O2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films.

  12. Natural gas flow through critical nozzles

    NASA Technical Reports Server (NTRS)

    Johnson, R. C.

    1969-01-01

    Empirical method for calculating both the mass flow rate and upstream volume flow rate through critical flow nozzles is determined. Method requires knowledge of the composition of natural gas, and of the upstream pressure and temperature.

  13. Spark gap switch with spiral gas flow

    DOEpatents

    Brucker, John P.

    1989-01-01

    A spark gap switch having a contaminate removal system using an injected gas. An annular plate concentric with an electrode of the switch defines flow paths for the injected gas which form a strong spiral flow of the gas in the housing which is effective to remove contaminates from the switch surfaces. The gas along with the contaminates is exhausted from the housing through one of the ends of the switch.

  14. Swirling flow of a dissociated gas

    NASA Technical Reports Server (NTRS)

    Wolfram, W. R., Jr.; Walker, W. F.

    1975-01-01

    Most physical applications of the swirling flow, defined as a vortex superimposed on an axial flow in the nozzle, involve high temperatures and the possibility of real gas effects. The generalized one-dimensional swirling flow in a converging-diverging nozzle is analyzed for equilibrium and frozen dissociation using the ideal dissociating gas model. Numerical results are provided to illustrate the major effects and to compare with results obtained for a perfect gas with constant ratio of specific heats. It is found that, even in the case of real gases, perfect gas calculations can give a good estimate of the reduction in mass flow due to swirl.

  15. Consequences of N2 gas flow variation on properties of zirconium oxide-nitride films

    NASA Astrophysics Data System (ADS)

    Jariwala, Nayan N.; Chauhan, Kamlesh V.; Pandya, Parth P.; Patel, Nicky P.; Rawal, Sushant K.

    2016-09-01

    Zirconium oxide-nitride films was prepared by RF reactive magnetron sputtering in presence of helium, oxygen and nitrogen gases. The N2 gas flow rate was varied for each consecutive run of sputtering at values of 66, 72, 78, 84, and 90 sccm respectively. Zirconium oxide-nitride films showed structural variation in evolution of various textures as detected by X-ray diffraction. It showed good transmission values above 50% for all samples. Wettability studies of zirconium oxide-nitride films was done by contact angle goniometer. All samples depict hydrophobic behaviour as all films have contact angle values above 90° and as nitrogen gas flow rate increases, the films roughness as well as contact angle increases. Tribological test is done on zirconium oxide-nitride films coated on aluminium, brass and mild steel pins, which give excellent wear resistance compared to uncoated pins.

  16. Advances in gas-liquid flows 1990

    SciTech Connect

    Kim, J.M. . Nuclear Reactor Lab.); Rohatgi, U.S. ); Hashemi, A. )

    1990-01-01

    Gas-liquid two-phase flows commonly occur in nature and industrial applications. Rain, clouds, geysers, and waterfalls are examples of natural gas-liquid flow phenomena, whereas industrial applications can be found in nuclear reactors, steam generators, boilers, condensers, evaporators, fuel atomization, heat pipes, electronic equipment cooling, petroleum engineering, chemical process engineering, and many others. The household-variety phenomena such as garden sprinklers, shower, whirlpool bath, dripping faucet, boiling tea pot, and bubbling beer provide daily experience of gas-liquid flows. The papers presented in this volume reflect the variety and richness of gas-liquid two-phase flow and the increasing role it plays in modern technology. This volume contains papers dealing with some recent development in gas-liquid flow science and technology, covering basic gas-liquid flows, measurements and instrumentation, cavitation and flashing flows, countercurrent flow and flooding, flow in various components and geometries liquid metals and thermocapillary effects, heat transfer, nonlinear phenomena, instability, and other special and general topics related to gas-liquid flows.

  17. Formation Mechanism of Fe Nanocubes by Magnetron Sputtering Inert Gas Condensation.

    PubMed

    Zhao, Junlei; Baibuz, Ekaterina; Vernieres, Jerome; Grammatikopoulos, Panagiotis; Jansson, Ville; Nagel, Morten; Steinhauer, Stephan; Sowwan, Mukhles; Kuronen, Antti; Nordlund, Kai; Djurabekova, Flyura

    2016-04-26

    In this work, we study the formation mechanisms of iron nanoparticles (Fe NPs) grown by magnetron sputtering inert gas condensation and emphasize the decisive kinetics effects that give rise specifically to cubic morphologies. Our experimental results, as well as computer simulations carried out by two different methods, indicate that the cubic shape of Fe NPs is explained by basic differences in the kinetic growth modes of {100} and {110} surfaces rather than surface formation energetics. Both our experimental and theoretical investigations show that the final shape is defined by the combination of the condensation temperature and the rate of atomic deposition onto the growing nanocluster. We, thus, construct a comprehensive deposition rate-temperature diagram of Fe NP shapes and develop an analytical model that predicts the temporal evolution of these properties. Combining the shape diagram and the analytical model, morphological control of Fe NPs during formation is feasible; as such, our method proposes a roadmap for experimentalists to engineer NPs of desired shapes for targeted applications. PMID:26962973

  18. Formation Mechanism of Fe Nanocubes by Magnetron Sputtering Inert Gas Condensation.

    PubMed

    Zhao, Junlei; Baibuz, Ekaterina; Vernieres, Jerome; Grammatikopoulos, Panagiotis; Jansson, Ville; Nagel, Morten; Steinhauer, Stephan; Sowwan, Mukhles; Kuronen, Antti; Nordlund, Kai; Djurabekova, Flyura

    2016-04-26

    In this work, we study the formation mechanisms of iron nanoparticles (Fe NPs) grown by magnetron sputtering inert gas condensation and emphasize the decisive kinetics effects that give rise specifically to cubic morphologies. Our experimental results, as well as computer simulations carried out by two different methods, indicate that the cubic shape of Fe NPs is explained by basic differences in the kinetic growth modes of {100} and {110} surfaces rather than surface formation energetics. Both our experimental and theoretical investigations show that the final shape is defined by the combination of the condensation temperature and the rate of atomic deposition onto the growing nanocluster. We, thus, construct a comprehensive deposition rate-temperature diagram of Fe NP shapes and develop an analytical model that predicts the temporal evolution of these properties. Combining the shape diagram and the analytical model, morphological control of Fe NPs during formation is feasible; as such, our method proposes a roadmap for experimentalists to engineer NPs of desired shapes for targeted applications.

  19. Sputtering of the Europa surface by thermal ions from the torus and pickup ions in a diverted flow

    NASA Astrophysics Data System (ADS)

    Dols, Vincent J.; Cassidy, Timothy A.; Bagenal, Fran; Crary, Frank; Delamere, Peter A.

    2016-10-01

    Europa's atmosphere is very tenuous and is mainly composed of O2. It is thought to be produced by ion bombardment of its icy surface. Several ion populations may contribute to this sputtering:1) The thermal plasma of the torus (~ 1keV including ram velocity), which may be partially diverted around the moon by the ionospheric currents2) The energetic sulfur and hydrogen ions (~10 keV-MeV), which diffuse inward toward Europa's orbit3) and possibly the newly ionized O2 molecules that are picked up by the torus flow and hit the surface.The relative contribution of each sputtering ion population has been debated for more than three decades with estimated O2 sputtering rates varying by ~2 order of magnitude. Modelers have historically focused on a single piece of the puzzle: plasma modelers assume a static atmosphere and tend not to check that their sources and losses are consistent with their prescribed atmosphere; while atmospheric modelers neglect the electro-dynamic interaction that diverts torus plasma around the moon, and limits the ion flux to the surface.In this work, we present a first step to compute self-consistently the atmospheric production by the bombardment of the thermal plasma and pickup O2+ ions.1) We calculate the plasma flow around Europa with a MHD model2) We use this flow in a multi-species physical chemistry model of the plasma-atmosphere interaction to compute the ion fluxes into Europa's surface.3) We compute the production rate of O2 resulting from the ice sputtering by thermal and pickup ions and compare the resulting atmospheric source rate to previously published results.

  20. Water and methanol in low-mass protostellar outflows: gas-phase synthesis, ice sputtering and destruction

    NASA Astrophysics Data System (ADS)

    Suutarinen, A. N.; Kristensen, L. E.; Mottram, J. C.; Fraser, H. J.; van Dishoeck, E. F.

    2014-05-01

    Water in outflows from protostars originates either as a result of gas-phase synthesis from atomic oxygen at T ≳ 200 K, or from sputtered ice mantles containing water ice. We aim to quantify the contribution of the two mechanisms that lead to water in outflows, by comparing observations of gas-phase water to methanol (a grain surface product) towards three low-mass protostars in NGC 1333. In doing so, we also quantify the amount of methanol destroyed in outflows. To do this, we make use of James Clerk Maxwell Telescope and Herschel-Heterodyne Instrument for the Far-Infrared data of H2O, CH3OH and CO emission lines and compare them to RADEX non-local thermodynamic equilibrium excitation simulations. We find up to one order of magnitude decrease in the column density ratio of CH3OH over H2O as the velocity increases in the line wings up to ˜15 km s-1. An independent decrease in X(CH3OH) with respect to CO of up to one order of magnitude is also found in these objects. We conclude that gas-phase formation of H2O must be active at high velocities (above 10 km s-1 relative to the source velocity) to re-form the water destroyed during sputtering. In addition, the transition from sputtered water at low velocities to form water at high velocities must be gradual. We place an upper limit of two orders of magnitude on the destruction of methanol by sputtering effects.

  1. Apparatus for focusing flowing gas streams

    DOEpatents

    Nogar, N.S.; Keller, R.A.

    1985-05-20

    Apparatus for focusing gas streams. The principle of hydrodynamic focusing is applied to flowing gas streams in order to provide sample concentration for improved photon and sample utilization in resonance ionization mass spectrometric analysis. In a concentric nozzle system, gas samples introduced from the inner nozzle into the converging section of the outer nozzle are focused to streams 50-250-..mu..m in diameter. In some cases diameters of approximately 100-..mu..m are maintained over distances of several centimeters downstream from the exit orifice of the outer nozzle. The sheath gas employed has been observed to further provide a protective covering around the flowing gas sample, thereby isolating the flowing gas sample from possible unwanted reactions with nearby surfaces. A single nozzle variation of the apparatus for achieving hydrodynamic focusing of gas samples is also described.

  2. Flow rate measuring devices for gas flows

    NASA Astrophysics Data System (ADS)

    Bonfig, K. W.

    1985-07-01

    Flowrate measuring devices are described: volume meter with fixed or mobile walls; turbine meter; throttling procedure; ultrasonic and Doppler methods; vortex method; rotary flowmeter; and swinging body flow measuring procedure. Flowrate can also be measured from the force exerted on bodies immersed in a fluid or based on thermodynamical principles. The characteristics and operating envelope of each device/method are given.

  3. Sputtering Yields for Mixtures of Organic Materials Using Argon Gas Cluster Ions.

    PubMed

    Seah, M P; Havelund, R; Shard, A G; Gilmore, I S

    2015-10-22

    The sputtering yield volumes of binary mixtures of Irganox 1010 with either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine (FMOC) have been measured for 5 keV Ar2000(+) ions incident at 45° to the surface normal. The sputtering yields are determined from the doses to sputter through various compositions of 100 nm thick, intimately mixed, layers. Because of matrix effects, the profiles for secondary ions are distorted, and profile shifts in depth of 15 nm are observed leading to errors above 20% in the deduced sputtering yield. Secondary ions are selected to avoid this. The sputtering yield volumes for the mixtures are shown to be lower than those deduced from a linear interpolation from the pure materials. This is shown to be consistent with a simple model involving the changing energy absorbed for the sputtering of intimate mixtures. Evidence to support this comes from the secondary ion data for pairs of the different molecules. Both binary mixtures behave similarly, but matrix effects are stronger for the Irganox 1010/FMOC system.

  4. Liquid/Gas Flow Mixers

    NASA Technical Reports Server (NTRS)

    Fabris, Gracio

    1994-01-01

    Improved devices mix gases and liquids into bubbly or foamy flows. Generates flowing, homogeneous foams or homogeneous dispersions of small, noncoalescing bubbles entrained in flowing liquids. Mixers useful in liquid-metal magnetohydrodynamic electric-power generator, froth flotation in mining industry, wastewater treatment, aerobic digestion, and stripping hydrocarbon contaminants from ground water.

  5. Slip length measurement of gas flow.

    PubMed

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-16

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas. PMID:27505860

  6. Slip length measurement of gas flow

    NASA Astrophysics Data System (ADS)

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-01

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  7. Slip length measurement of gas flow.

    PubMed

    Maali, Abdelhamid; Colin, Stéphane; Bhushan, Bharat

    2016-09-16

    In this paper, we present a review of the most important techniques used to measure the slip length of gas flow on isothermal surfaces. First, we present the famous Millikan experiment and then the rotating cylinder and spinning rotor gauge methods. Then, we describe the gas flow rate experiment, which is the most widely used technique to probe a confined gas and measure the slip. Finally, we present a promising technique using an atomic force microscope introduced recently to study the behavior of nanoscale confined gas.

  8. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  9. Effect of Sputtering Gas environments on the Properties of Aluminum-doped Zinc Oxide Thin Films for Photovoltaic Application

    SciTech Connect

    Chauhan, Ram Narayan; Kumar, Jitendra; Singh, C.; Anand, R. S.

    2011-10-20

    Aluminum-doped zinc oxide thin films have been deposited on glass substrates by R.F. sputtering using ZnO(98%)-Al{sub 2}O{sub 3}(2%) target in different sputtering gaseous environments, viz., Ar, Ar/O{sub 2} and Ar/N{sub 2}+H{sub 2} at 80 deg. C. These films have been studied with regard to phase, microstructure, optical absorption and sheet resistance for application in photovoltaic devices as transparent conducting electrodes. The properties of the films are shown to strongly depend on the sputtering gas(es). The films exhibit a wurtzite-type hexagonal structure with the (00.2) preferred orientation, the c-axis perpendicular to the substrate. The intensity of 00.2 diffraction peak and the average crystallite size remain almost the same when the films are prepared under pure Ar or Ar/O{sub 2} environment. However the average crystallite size increases while electrical resistance decreases with introduction of nitrogen and hydrogen in comparison to oxygen in argon. Nevertheless, the optimum value of optical transmittance and sheet resistance of the films deposited in pure argon are found to be 85-96% in the wavelength range 400-800 nm and 65 {Omega}/{open_square}, respectively.

  10. A method of determining combustion gas flow

    NASA Technical Reports Server (NTRS)

    Bon Tempi, P. J.

    1968-01-01

    Zirconium oxide coating enables the determination of hot gas flow patterns on liquid rocket injector face and baffle surfaces to indicate modifications that will increase performance and improve combustion stability. The coating withstands combustion temperatures and due to the coarse surface and coloring of the coating, shows the hot gas patterns.

  11. Fluorescent particles enable visualization of gas flow

    NASA Technical Reports Server (NTRS)

    Wilson, A. J.

    1968-01-01

    Fluorescent particles enable visualization of the flow patterns of gases at slow velocities. Through a transparent section in the gas line, a camera views the visible light emitted by the particles carried by the gas stream. Fine definition of the particle tracks are obtained at slow camera shutter speeds.

  12. Cleanouts boost Devonian shale gas flow

    SciTech Connect

    Not Available

    1991-02-04

    Cleaning shale debris from the well bores is an effective way to boost flow rates from old open hole Devonian shale gas wells, research on six West Virginia wells begun in 1985 has shown. Officials involved with the study say the Appalachian basin could see 20 year recoverable gas reserves hiked by 315 bcf if the process is used on a wide scale.

  13. Gas Adsorption Properties of Fluorocarbon Thin Films Prepared Using Three Different Types of RF Magnetron Sputtering Systems

    NASA Astrophysics Data System (ADS)

    Satoru Iwamori,; Norihiko Hasegawa,; Satoshi Yano,; Kazutoshi Noda,

    2010-04-01

    Fluorocarbon thin films were deposited onto a quartz crystal with a poly(tetrafluoroethylene) target using three different types of RF magnetron sputtering systems with strong, weak, and unbalanced magnetic fields. The adsorption properties of these thin films for water, ethanol, acetone, acetaldehyde, toluene, and methyl salicylate were evaluated using the quartz crystal microbalance (QCM) method in order to characterize the surface properties of these thin films. These thin films have low sensitivities to non-polar solvents that contain methyl and aromatic groups, and high sensitivities to polar solvents that contain carbonyl and hydroxyl groups. Chemical structures, especially, polar moieties in these fluorocarbon thin films would affect the gas adsorption properties.

  14. Effects of Ti addiction in WO 3 thin film ammonia gas sensor prepared by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hu, Ming; Yong, Cholyun; Feng, Youcai; Lv, Yuqiang; Han, Lei; Liang, Jiran; Wang, Haopeng

    2006-11-01

    WO 3 sensing films (1500 Å) were deposited using dc reactive magnetron sputtering method on alumina substrate on which patterned interdigital Pt electrodes were previously formed. The additive Ti was sputtered with different thickness (100-500 Å) onto WO 3 thin films and then the films as-deposited were annealed at 400°C in air for 3h. The crystal structure and chemical composition of the films were characterized by XRD and XPS analysis. The effect of Ti addition on sensitive properties of WO 3 thin film to the NH 3 gas was then discussed. WO 3 thin films added Ti revealed excellent sensitivity and response characteristics in the presence of low concentration of NH 3 (5-400 ppm) gas in air at 200°C operating temperature. Especially,in case 300 Å thickness of additive Ti, WO 3 thin films have a promotional effect on the response speed to NH 3 and selectivity enhanced with respect to other gases (CO, C IIH 5OH, CH 4). The influence of different substrates, including alumina, silicon and glass, on sensitivity to NH 3 gas has also been investigated.

  15. Inhalational anaesthesia with low fresh gas flow

    PubMed Central

    Hönemann, Christian; Hagemann, Olaf; Doll, Dietrich

    2013-01-01

    During the inhalation of anaesthesia use of low fresh gas flow (0.35-1 L/min) has some important advantages. There are three areas of benefit: pulmonary - anaesthesia with low fresh gas flow improves the dynamics of inhaled anaesthesia gas, increases mucociliary clearance, maintains body temperature and reduces water loss. Economic - reduction of anaesthesia gas consumption resulting in significant savings of > 75% and Ecological - reduction in nitrous oxide consumption, which is an important ozone-depleting and heat-trapping greenhouse gas that is emitted. Nevertheless, anaesthesia with high fresh gas flows of 2-6 L/min is still performed, a technique in which rebreathing is practically negligible. This special article describes the clinical use of conventional plenum vaporizers, connected to the fresh gas supply to easily perform low (1 L/min), minimal (0.5 L/min) or metabolic flow anaesthesia (0.35 L/min) with conventional Primus Draeger® anaesthesia machines in routine clinical practice. PMID:24163447

  16. Morphology and Oxide Shell Structure of Iron Nanoparticles Grown by Sputter-Gas-Aggregation

    SciTech Connect

    Wang, Chong M.; Baer, Donald R.; Amonette, James E.; Engelhard, Mark H.; Qiang, You; Antony, Jiji

    2007-06-27

    Much recent research effort has been made on the synthesis, characterization, and property evaluation of core-shell structured Fe nanoparticles. Fundamental properties of these particles depend on both their external crystal faceting planes and the nature of a protective oxide layer. In this paper, the crystal faceting planes and oxide coating structures of core-shell structured iron/iron oxide nanoparticles synthesized by a sputter-gas-aggregation process were studied using transmission electron microscopy (TEM), electron diffraction and Wulff shape construction. The particles grown by this process and deposited on a support at room temperature process have been compared with particles grown and deposited at high temperature as reported in literature. Most synthesis processes produce round particles for particles less than 20 nm in diameter. For larger particles crystallographic facets are observed. It has been found that the Fe nanoparticles formed at RT are invariantly faceted on the {100} lattice planes and truncated by the {110} planes at different degrees. Substantial fraction of particles are confined only by the 6 {100} planes (not truncated by the {110} planes), this contrasts with the Fe particles formed at high temperature (HT) for which a predominance of {110} planes has been reported. Furthermore, at RT no particle was identified to be only confined by the 12 {110} planes which is relatively common for the particles formed at HT. The Fe cubes defined by the 6 {100} planes show a characteristic inward relaxation along the <100> and <110> directions and the reason for this behavior is not fully understood. The oxide shell on the Fe {100} plane maintains an orientation relationship: Fe(001)//Fe3O4(001) and Fe[100]//Fe3O4[110], which is same as the oxide formed on a bulk Fe(001) through thermal oxidation. Orientation of the oxide that forms on the Fe{110} facets differs from that on Fe{001}, therefore, properties of core-shell structured Fe nanoparticle

  17. Heavy Gas Dispersion Incompressible Flow

    1992-01-27

    FEM3 is a numerical model developed primarily to simulate heavy gas dispersion in the atmosphere, such as the gravitational spread and vapor dispersion that result from an accidental spill of liquefied natural gas (LNG). FEM3 solves both two and three-dimensional problems and, in addition to the generalized anelastic formulation, includes options to use either the Boussinesq approximation or an isothermal assumption, when appropriate. The FEM3 model is composed of three parts: a preprocessor PREFEM3, themore » main code FEM3, and two postprocessors TESSERA and THPLOTX.« less

  18. Physical Sputtering vs. Gas Assisted Etching of Silicon Dioxide with a Gallium Focused Ion Beam: Elucidating Experiments via Monte Carlo Simulations

    NASA Astrophysics Data System (ADS)

    Timilsina, Rajendra; Tan, Shida; Livengood, Richard; Rack, Philip

    2015-03-01

    In order to increase ion beam nanomachining precision and improve imaging resolution, fine tuning of the ion beam profile is absolutely necessary. To understand the effects of ion beam tails, experiments and Monte Carlo simulations were conducted with a 40 keV gallium beam with and without gas assisted chemical etching. A gallium ion beam was scanned in an area of 25x25 nm2 on a silicon dioxide film with and without a localized XeF2 gas at 1pA current. Four different ion doses (0.23, 0.9, 1.8 and 3.6 nC/ μm2) were experimentally considered to study the sputtered and etched via profiles. Monte Carlo simulations using EnvizION program was performed to elucidate the sputtered and gas-assisted etch process. New features including gas-assisted etching by secondary electrons and a binary collision model to dissociate the precursor molecules were introduced. Sputtered via and gas assisted etching (XeF2 precursor gas) via profiles with various gas-assist pressures were studied to understand the experimental temporal behavior. Various contributions including sputtering from primary, forward scattered, backscattered ions as well as etching by recoiled atoms and secondary electrons will be discussed.

  19. Heavy Gas Dispersion Incompressible Flow

    1992-02-03

    FEM3 is a numerical model developed primarily to simulate heavy gas dispersion in the atmosphere, such as the gravitational spread and vapor dispersion that result from an accidental spill of liquefied natural gas (LNG). FEM3 solves both two and three-dimensional problems and, in addition to the generalized anelastic formulation, includes options to use either the Boussinesq approximation or an isothermal assumption, when appropriate. The FEM3 model is composed of three parts: a preprocessor PREFEM3, themore » main code FEM3, and two postprocessors TESSERA and THPLOTX. The DEC VAX11 version contains an auxiliary program, POLYREAD, which reads the polyplot file created by FEM3.« less

  20. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Raw exhaust gas flow. 89.416 Section 89... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods... procedure has been incorporated by reference. See § 89.6.) and calculation of the exhaust gas flow...

  1. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Raw exhaust gas flow. 89.416 Section... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods... procedure has been incorporated by reference. See § 89.6.) and calculation of the exhaust gas flow...

  2. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Raw exhaust gas flow. 89.416 Section... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods... procedure has been incorporated by reference. See § 89.6.) and calculation of the exhaust gas flow...

  3. The digital control of anaesthetic gas flow.

    PubMed

    Boaden, R W; Hutton, P

    1986-04-01

    The theory and construction of a prototype digital gas flow controller are described. Using eight preset needle valves, it has the ability to deliver any flow from 50 to 12750 ml/minute in steps of 50 ml/minute. Under given conditions, the accuracy of this device is very high and its variation in performance with pipeline supply pressures is quantified. The required flow is requested from a BBC 'B' microcomputer which is interfaced with the equipment via a program written in Basic and the 1MHz bus port. The possible uses and potential of a microcomputer-controlled flow regulator in anaesthesia and intensive care are discussed.

  4. The digital control of anaesthetic gas flow.

    PubMed

    Boaden, R W; Hutton, P

    1986-04-01

    The theory and construction of a prototype digital gas flow controller are described. Using eight preset needle valves, it has the ability to deliver any flow from 50 to 12750 ml/minute in steps of 50 ml/minute. Under given conditions, the accuracy of this device is very high and its variation in performance with pipeline supply pressures is quantified. The required flow is requested from a BBC 'B' microcomputer which is interfaced with the equipment via a program written in Basic and the 1MHz bus port. The possible uses and potential of a microcomputer-controlled flow regulator in anaesthesia and intensive care are discussed. PMID:2939766

  5. Sputtered gas-phase dianions detected by high-sensitivity mass spectrometry

    NASA Astrophysics Data System (ADS)

    Gnaser, Hubert; Golser, Robin

    2006-10-01

    The detection of small doubly-charged molecular anions by means of highly sensitive mass spectrometry is discussed. The production of these gas-phase dianions is accomplished by sputtering the specimen with Cs + ions with an energy of a few keV. It is demonstrated that dianions can be detected most easily when the molecular ion has an odd total mass; then, the dianions will show up at half-integral mass numbers in the mass spectrum. In addition, the agreement of the relative abundances of several isotopomers of a dianion with the nominal isotopic pattern corroborates the identification of a dianionic species in the mass spectrum. These features are exemplified by monitoring mixed silicon-oxygen dianions of the general form OO52-[28], Sn2-[29], SiC62-[30], BeCn2-[31], and PtX62- (X = F, Cl, Br) [32]. More recent work of this group investigated the existence of long-lived dianions containing tetrahedrally coordinated oxygen atoms, namely, O(C)42- and O(BN)42-[33], of cyclic carbon cluster dianions [34], of tetraborates [35], of derivatives of the closo-hexaborate dianion BH62-[36], and of aromatic dianions [37]. Apart from identifying (meta)stable dianions, these computations indicated a possible general formation principle: small dianions are expected to be particularly stable if they consist of a central, at least partially positively charged atom and several equivalent negatively charged ligands [2,6,30,38]. Furthermore, it was pointed out [31,39,40] that for multiply charged anions a repulsive Coulomb barrier for electron emission exists which may result in small metastable dianions which can be detected by mass spectrometry. In fact, the existence of such a Coulomb barrier was inferred from various experiments [41-47]. Apart from dianions, Cederbaum and coworkers studied different small MCAs [19,24,25,48-50]. Theoretical work by other groups [51-59] corroborated and diversified these results. Following the experimental detection of Cn2-[12], several different

  6. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Raw exhaust gas flow. 89.416 Section... Procedures § 89.416 Raw exhaust gas flow. The exhaust gas flow shall be determined by one of the methods...) Measurement of the air flow and the fuel flow by suitable metering systems (for details see SAE J244....

  7. Pressure Calculations in Nanochannel Gas Flows

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Frijns, A. J. H.; Nedea, S. V.; van Steenhoven, A. A.

    2012-05-01

    In this research, pressure driven flow within a nanochannel is studied for argon in rarefied gas states. A Molecular Dynamics simulation is used to resolve the density and stress variations. Normal stress calculations are based on Irving-Kirkwood method, which divides the stress tensor into its kinetic and virial parts. The kinetic component recovers pressure based on the ideal-gas law. The particle-particle virial increases with increased density. The kinetic part and the virial part of the pressure is studied from Kn = 0.1 to Kn = 0.5 at 300 K. This pressure calculation was also compared with a simulation for a static fluid. Pressure driven gas flow gives a different result compared to static situation, which has a uniform particle distribution across the system. For a flow situation, the virial part is no longer the same. This can also be predicted from the virial equation and by the fact that the compressible fluid flow causes a temperature and density difference along the flow direction. The relation between the virial and distribution of particles has been studied further to understand the nature of virial component along the flow direction in compressible flows.

  8. The influence of sputtering power and O{sub 2}/Ar flow ratio on the performance and stability of Hf-In-Zn-O thin film transistors under illumination

    SciTech Connect

    Kim, Hyun-Suk; Park, Kyung-Bae; Son, Kyoung Seok; Park, Joon Seok; Maeng, Wan-Joo; Kim, Tae Sang; Lee, Kwang-Hee; Kim, Eok Su; Lee, Jiyoul; Suh, Joonki; Seon, Jong-Baek; Ryu, Myung Kwan; Lee, Sang Yoon; Lee, Kimoon; Im, Seongil

    2010-09-06

    The performance and stability of amorphous HfInZnO thin film transistors under visible light illumination were studied. The extent of device degradation upon negative bias stress with the presence of visible light is found to be strongly sensitive to the extent of photoelectric effect in the oxide semiconductor. Highly stable devices were fabricated by optimizing the deposition conditions of HfInZnO films, where the combination of high sputtering power and high O{sub 2}/Ar gas flow ratio was found to result in the highest stability under bias stress experiments.

  9. Flowmeter for gas-entrained solids flow

    DOEpatents

    Porges, Karl G.

    1990-01-01

    An apparatus and method for the measurement of solids feedrate in a gas-entrained solids flow conveyance system. The apparatus and method of the present invention include a vertical duct connecting a source of solids to the gas-entrained flow conveyance system, a control valve positioned in the vertical duct, and a capacitive densitometer positioned along the duct at a location a known distance below the control valved so that the solid feedrate, Q, of the gas entrained flow can be determined by Q=S.rho..phi.V.sub.S where S is the cross sectional area of the duct, .rho. is the density of the solid, .phi. is the solid volume fraction determined by the capacitive densitometer, and v.sub.S is the local solid velocity which can be inferred from the konown distance of the capacitive densitometer below the control valve.

  10. Controlling Gas-Flow Mass Ratios

    NASA Technical Reports Server (NTRS)

    Morris, Brian G.

    1990-01-01

    Proposed system automatically controls proportions of gases flowing in supply lines. Conceived for control of oxidizer-to-fuel ratio in new gaseous-propellant rocket engines. Gas-flow control system measures temperatures and pressures at various points. From data, calculates control voltages for electronic pressure regulators for oxygen and hydrogen. System includes commercially available components. Applicable to control of mass ratios in such gaseous industrial processes as chemical-vapor depostion of semiconductor materials and in automotive engines operating on compressed natural gas.

  11. Gas transfer in a bubbly wake flow

    NASA Astrophysics Data System (ADS)

    Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

    2016-05-01

    The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

  12. Rarefied gas flow through nanoscale tungsten channels.

    PubMed

    Ozhgibesov, M S; Leu, T S; Cheng, C H

    2013-05-01

    The aim of this work is to investigate argon flow behaviors through the channels with three types of boundary conditions. Current work deals with numerical simulations of rarefied gas flow through nano-channels using the Molecular Dynamics method. Taking into account that this method is very time consuming, we implemented all the simulations using CUDA capable graphic cards. We found that the well-known and relatively simple Maxwell model of boundary conditions is able to reproduce gas flow through a tungsten channel with irregularities and roughness, while it results in a significant error in the case of a smooth metal surface. We further found that the flow rate through a relatively short channel correlates nonlinearly with the channel's length. This finding is in contrast with the results available in extant literature. Our results are important for both numerical and theoretical analyses of rarefied gas flow in micro- and nano-systems where the choice of boundary conditions significantly influences flow. PMID:23528809

  13. SEMICONDUCTOR DEVICES: An MWCNT-doped SNO2 thin film NO2 gas sensor by RF reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wei, Lin; Shizhen, Huang; Wenzhe, Chen

    2010-02-01

    An MWCNT-doped (multi-walled carbon nanotube) SnO2 thin film NO2 gas sensor, prepared by radio frequency reactive magnetron sputtering, showed a high sensitivity to ultra-low concentrations of NO2 in the parts per billion range. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM) characterizations indicated that the MWCNTs were affected by the morphology of the SnO2 thin film and the particle size. The properties of the MWCNT-doped SnO2 sensor, such as sensitivity, selectivity, and response-recovery time, were investigated. Experimental results revealed that the MWCNT-doped SnO2 thin film sensor response to NO2 gas depended on the operating temperature, NO2 gas concentration, thermal treatment conditions, film thickness, and so on. The mechanism of the gas-sensing property of the MWCNT-doped Sn22 thin film sensor was investigated and showed that the improved gas-sensing performance should be attributed to the effects between MWCNTs (p-type) and SnO2 (n-type) semiconductors.

  14. Synthesis, characterization, and hydrogen gas sensing properties of AuNs-catalyzed ZnO sputtered thin films

    NASA Astrophysics Data System (ADS)

    Drmosh, Q. A.; Yamani, Z. H.

    2016-07-01

    Hydrogen present in concentration up to 4 vol.% forms an explosive mixture with air. Its propensity to escape in the event of leak, could lead to quick build-up and formation of an explosive mixture with air in confined spaces, such as an automobile. This necessitates its detection at very low concentration. Zinc oxide (ZnO) is a well-known wide band gap (∼3.37 eV) semiconducting oxide that has been widely used for gas sensing applications. This work reports on the fabrication, characterization and gas sensing performance of nanogold decorated ZnO thin films made by DC reactive sputtering. The sensor films were fabricated by depositing a very thin layer of gold on the sputtered ZnO thin film. The as deposited Au@ZnO films were converted into highly crystalline ZnO film covered with gold nanostructures (AuNs@ZnO) by mild heat treatment. The structural and morphological as well as the compositional homogeneity of the as-deposited and heat-treated ZnO, Au@ZnO and AuNs@ZnO thin films were ascertained. The gas sensing behavior of the AuNs@ZnO thin films towards hydrogen as a function of temperature at different H2 concentrations was investigated and compared with that of pure and heat-treated ZnO films. The effect of the presence of gold nanoparticles on imparting improvement (in terms of higher response signal, high reproducibility and complete reversibility) was established; the optimal operating temperature was about 400 °C. A plausible mechanism for the observed enhancement in the sensing behavior of AuNs@ZnO films towards H2 is proposed.

  15. Depth resolution at organic interfaces sputtered by argon gas cluster ions: the effect of energy, angle and cluster size.

    PubMed

    Seah, M P; Spencer, S J; Havelund, R; Gilmore, I S; Shard, A G

    2015-10-01

    An analysis is presented of the effect of experimental parameters such as energy, angle and cluster size on the depth resolution in depth profiling organic materials using Ar gas cluster ions. The first results are presented of the incident ion angle dependence of the depth resolution, obtained at the Irganox 1010 to silicon interface, from profiles by X-ray photoelectron spectrometry (XPS). By analysis of all relevant published depth profile data, it is shown that such data, from delta layers in secondary ion mass spectrometry (SIMS), correlate with the XPS data from interfaces if it is assumed that the monolayers of the Irganox 1010 adjacent to the wafer substrate surface have an enhanced sputtering rate. SIMS data confirm this enhancement. These results show that the traditional relation for the depth resolution, FWHM = 2.1Y(1/3) or slightly better, FWHM = P(X)Y(1/3)/n(0.2), where n is the argon gas cluster size, and P(X) is a parameter for each material are valid both at the 45° incidence angle of the argon gas cluster sputtering ions used in most studies and at all angles from 0° to 80°. This implies that, for optimal depth profile resolution, 0° or >75° incidence may be significantly better than the 45° traditionally used, especially for the low energy per atom settings required for the best resolved profiles in organic materials. A detailed analysis, however, shows that the FWHM requires a constant contribution added in quadrature to the above such that there are minimal improvements at 0° or greater than 75°. A critical test at 75° confirms the presence of this constant contribution.

  16. Continuous-Flow Gas-Phase Bioreactors

    NASA Technical Reports Server (NTRS)

    Wise, Donald L.; Trantolo, Debra J.

    1994-01-01

    Continuous-flow gas-phase bioreactors proposed for biochemical, food-processing, and related industries. Reactor contains one or more selected enzymes dehydrated or otherwise immobilized on solid carrier. Selected reactant gases fed into reactor, wherein chemical reactions catalyzed by enzyme(s) yield product biochemicals. Concept based on discovery that enzymes not necessarily placed in traditional aqueous environments to function as biocatalysts.

  17. Structural analysis of the outermost hair surface using TOF-SIMS with gas cluster ion beam sputtering.

    PubMed

    Lshikawa, Kazutaka; Okamoto, Masayuki; Aoyagi, Satoka

    2016-06-28

    A hair cuticle, which consists of flat overlapping scales that surround the hair fiber, protects inner tissues against external stimuli. The outermost surface of the cuticle is covered with a thin membrane containing proteins and lipids called the epicuticle. In a previous study, the authors conducted a depth profile analysis of a hair cuticle's amino acid composition to characterize its multilayer structure. Time-of-flight secondary ion mass spectrometry with a bismuth primary ion source was used in combination with the C60 sputtering technique for the analysis. It was confirmed that the lipids and cysteine-rich layer exist on the outermost cuticle surface, which is considered to be the epicuticle, though the detailed structure of the epicuticle has not been clarified. In this study, depth profile analysis of the cuticle surface was conducted using the argon gas cluster ion beam (Ar-GCIB) sputtering technique, in order to characterize the structure of the epicuticle. The shallow depth profile of the cuticle surface was investigated using an Ar-GCIB impact energy of 5 keV. Compared to the other amino acid peaks rich in the epicuticle, the decay of 18-methyleicosanic acid (18-MEA) thiolate peak was the fastest. This result suggests that the outermost surface of the hair is rich in 18-MEA. In conclusion, our results indicate that the outermost surfaces of cuticles have a multilayer (lipid and protein layers), which is consistent with the previously proposed structure.

  18. PdPt catalyst synthesized using a gas aggregation source and magnetron sputtering for fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Caillard, A.; Cuynet, S.; Lecas, T.; Andreazza, P.; Mikikian, M.; Thomann, A.-L.; Brault, P.

    2015-12-01

    PdPt catalysts with different morphologies and atomic ratios have been synthesized on native SiO2/Si and on proton exchange membranes. The combination of the gas aggregation source and magnetron sputtering techniques allows the formation of quasi core-shell Pd0.97Pt0.03@Pt nanoclusters. Transmission electron microscopy and grazing incidence wide-angle x-ray scattering measurements of the Pd-rich core reveal a mean diameter of 4 nm and a face-centered cubic structure. The Pt shell around half of the Pd-rich core is formed by magnetron sputtering, and increases the nanocluster diameter (up to 10 nm) and the overall Pt content (up to 85%). Membranes coated by the PdPt core catalyst and PdPt@Pt catalyst (resulting in the formation of catalyst-coated membranes) are incorporated into fuel cells and their electrical characteristics are measured. The association of the two deposition techniques results in the formation of quasi core-shell PdPt@Pt nanoclusters, improving the start-up step of the fuel cell.

  19. Surface Effects on Nanoscale Gas Flows

    NASA Astrophysics Data System (ADS)

    Beskok, Ali; Barisik, Murat

    2010-11-01

    3D MD simulations of linear Couette flow of argon gas confined within nano-scale channels are performed in the slip, transition and free molecular flow regimes. The velocity and density profiles show deviations from the kinetic theory based predictions in the near wall region that typically extends three molecular diameters (s) from each surface. Utilizing the Irwin-Kirkwood theorem, stress tensor components for argon gas confined in nano-channels are investigated. Outside the 3s region, three normal stress components are identical, and equal to pressure predicted using the ideal gas law, while the shear stress is a constant. Within the 3s region, the normal stresses become anisotropic and the shear stress shows deviations from its bulk value due to the surface virial effects. Utilizing the kinetic theory and MD predicted shear stress values, the tangential momentum accommodation coefficient for argon gas interacting with FCC structured walls (100) plane facing the fluid is calculated to be 0.75; this value is independent of the Knudsen number. Results show emergence of the 3s region as an additional characteristic length scale in nano-confined gas flows.

  20. Control and enhancement of the oxygen storage capacity of ceria films by variation of the deposition gas atmosphere during pulsed DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Eltayeb, Asmaa; Vijayaraghavan, Rajani K.; McCoy, Anthony; Venkatanarayanan, Anita; Yaremchenko, Aleksey A.; Surendran, Rajesh; McGlynn, Enda; Daniels, Stephen

    2015-04-01

    In this study, nanostructured ceria (CeO2) films are deposited on Si(100) and ITO coated glass substrates by pulsed DC magnetron sputtering using a CeO2 target. The influence on the films of using various gas ambients, such as a high purity Ar and a gas mixture of high purity Ar and O2, in the sputtering chamber during deposition are studied. The film compositions are studied using XPS and SIMS. These spectra show a phase transition from cubic CeO2 to hexagonal Ce2O3 due to the sputtering process. This is related to the transformation of Ce4+ to Ce3+ and indicates a chemically reduced state of CeO2 due to the formation of oxygen vacancies. TGA and electrochemical cyclic voltammetry (CV) studies show that films deposited in an Ar atmosphere have a higher oxygen storage capacity (OSC) compared to films deposited in the presence of O2. CV results specifically show a linear variation with scan rate of the anodic peak currents for both films and the double layer capacitance values for films deposited in Ar/O2 mixed and Ar atmosphere are (1.6 ± 0.2) × 10-4 F and (4.3 ± 0.5) × 10-4 F, respectively. Also, TGA data shows that Ar sputtered samples have a tendency to greater oxygen losses upon reduction compared to the films sputtered in an Ar/O2 mixed atmosphere.

  1. 21 CFR 868.2885 - Gas flow transducer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gas flow transducer. 868.2885 Section 868.2885...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2885 Gas flow transducer. (a) Identification. A gas flow transducer is a device intended for medical purposes that is used to convert gas...

  2. 21 CFR 868.2885 - Gas flow transducer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas flow transducer. 868.2885 Section 868.2885...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2885 Gas flow transducer. (a) Identification. A gas flow transducer is a device intended for medical purposes that is used to convert gas...

  3. 21 CFR 868.2885 - Gas flow transducer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas flow transducer. 868.2885 Section 868.2885...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2885 Gas flow transducer. (a) Identification. A gas flow transducer is a device intended for medical purposes that is used to convert gas...

  4. Effect of oxygen flow rate on the properties of SiOx films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lai, Fachun; Li, Ming; Wang, Haiqian; Jiang, Yousong; Song, Yizhou

    2005-08-01

    SiOx (x=0--2) films were deposited on BK-7 substrates by a low frequency reactive magnetron sputtering system with the oxygen flow rate (OFR) changing from 0 to 30 sccm. The samples were characterized by atomic force microscopy, spectrophotometer, and X-ray photoelectron spectroscopy. The extinction coefficient and refractive index decrease, while the optical transmittance increases with the increase of OFR from 0 to 17 sccm. The root mean square surface roughness has a maximum at 10 sccm OFR. The highest deposition rate is at 15 sccm OFR. Our results show that the films deposited at 20 sccm OFR are stoichiometric silica with relatively high deposition rate, low extinction coefficient, and low surface roughness. Therefore, a precise control of OFR is very important to obtain high quality films for optical applications.

  5. Contamination removal by ion sputtering

    NASA Astrophysics Data System (ADS)

    Shaw, Christopher G.

    1990-11-01

    Experimental investigations are described for ion-beam sputtering and RF-plasma sputtering to determine the effectiveness of the methods for removing contaminants from an optical surface. The effects of ion-beam sputtering are tested with an ion gun and measured by mounting a 5-MHz quartz-crystal microbalance on a sample holder and simulating spacecraft contamination. RF-plasma sputtering involves the application of an alternating electric field to opposing electrodes immersed in a low density gas, and is tested with the same setup. The energy dependence of the sputtering yields is measured to determine whether the different contaminants are removed and whether the mirror surface is affected. Ion-beam sputtering removes all contaminants tested, but also affects the mirror surface at high energies. When the correct DC bias is applied, RF sputtering can remove the contaminants without removing the metal-mirror surface.

  6. SSME hot gas manifold flow comparison test

    NASA Technical Reports Server (NTRS)

    Cox, G. B., Jr.; Dill, C. C.

    1988-01-01

    An account is given of the High Pressure Fuel Turbopump (HPFT) component of NASA's Alternate Turbopump Development effort, which is aimed at the proper aerodynamic integration of the current Phase II three-duct SSME Hot Gas Manifold (HGM) and the future 'Phase II-plus' two-duct HGM. Half-scale water flow tests of both HGM geometries were conducted to provide initial design data for the HPFT. The results reveal flowfield results and furnish insight into the performance differences between the two HGM flowpaths. Proper design of the HPFT can potentially secure significant flow improvements in either HGM configuration.

  7. Auger electron nanoscale mapping and x-ray photoelectron spectroscopy combined with gas cluster ion beam sputtering to study an organic bulk heterojunction

    SciTech Connect

    Heon Kim, Seong; Heo, Sung; Ihn, Soo-Ghang; Yun, Sungyoung; Hwan Park, Jong; Chung, Yeonji; Lee, Eunha; Park, Gyeongsu; Yun, Dong-Jin

    2014-06-16

    The lateral and vertical distributions of organic p/n bulk heterojunctions for an organic solar cell device are, respectively, investigated using nanometer-scale Auger electron mapping and using X-ray photoelectron spectroscopy (XPS) with Ar gas cluster ion beam (GCIB) sputtering. The concentration of sulfur, present only in the p-type material, is traced to verify the distribution of p-type (donor) and n-type (acceptor) materials in the blended structure. In the vertical direction, a considerable change in atomic sulfur concentration is observed using XPS depth profiling with Ar GCIB sputtering. In addition, Auger electron mapping of sulfur reveals the lateral 2-dimensional distribution of p- and n-type materials. The combination of Auger electron mapping with Ar GCIB sputtering should thereby allow the construction of 3-dimensional distributions of p- and n-type materials in organic photovoltaic cells.

  8. Gas Flow Near a Young Gas Giant Planet

    NASA Astrophysics Data System (ADS)

    Lubow, S.

    2004-12-01

    The mass acquired by a gas giant planet has long been believed to result from accretion of material within the surrounding gaseous disk (nebula). Bate, D'Angelo, and I have analyzed the properties and consequences of this flow by means of three-dimensional hydrodynamical simulations. Most of the accretion occurs after the planet has partially cleared a gap in the surrounding disk. The flow through the gap leads to accretion within the planet's Hill sphere. In that region, a circumplanetary disk forms which can serve as a site for satellite formation. The flow onto this disk is fully three-dimensional and involves shock production. The nebula exerts a torque on the planet that causes it to migrate radially. We have recently examined the torques produced by the material within the gap and within the Hill sphere.

  9. Gas-Liquid Flow in Pipelines

    SciTech Connect

    Thomas J. Hanratty

    2005-02-25

    A research program was carried out at the University of Illinois in which develops a scientific approach to gas-liquid flows that explains their macroscopic behavior in terms of small scale interactions. For simplicity, fully-developed flows in horizontal and near-horizontal pipes. The difficulty in dealing with these flows is that the phases can assume a variety of configurations. The specific goal was to develop a scientific understanding of transitions from one flow regime to another and a quantitative understanding of how the phases distribute for a give regime. These basic understandings are used to predict macroscopic quantities of interest, such as frictional pressure drop, liquid hold-up, entrainment in annular flow and frequency of slugging in slug flows. A number of scientific issues are addressed. Examples are the rate of atomization of a liquid film, the rate of deposition of drops, the behavior of particles in a turbulent field, the generation and growth of interfacial waves. The use of drag-reducing polymers that change macroscopic behavior by changing small scale interactions was explored.

  10. Inspiratory flow and intrapulmonary gas distribution

    SciTech Connect

    Rehder, K.; Knopp, T.J.; Brusasco, V.; Didier, E.P.

    1981-01-01

    The effect of flow of inspired gas on intrapulmonary gas distribution was examined by analysis of regional pulmonary /sup 133/Xe clearances and of total pulmonary /sup 133/Xe clearance measured at the mouth after equilibration of the lungs with /sup 133/Xe. Five awake healthy volunteers (24 to 40 yr of age) and another 5 healthy, anesthetized-paralyzed volunteers (26 to 28 yr of age) were studied while they were in the right lateral decubitus position. The awake subjects were studied at 3 inspiratory flows (0.4, 0.7, and 1.0 L/s) and the anesthetized-paralyzed subjects at 4 inspiratory flows (0.2, 0.5, 1.1, and 1.6 L/s). Interregional differences in /sup 133/Xe clearances along the vertical axis were significantly less during anesthesia-paralysis and mechanical ventilation than during spontaneous breathing in the awake state. No differences in the regional or total pulmonary /sup 133/Xe clearances were detected at these different flows in either of the two states, i.e., the difference between the awake and anesthetized-paralyzed states persisted.

  11. Mechanical properties of Ta-Al-N thin films deposited by cylindrical DC magnetron sputtering: Influence of N2% in the gas mixture

    NASA Astrophysics Data System (ADS)

    Darabi, Elham; Moghaddasi, Naghmeh; Reza Hantehzadeh, Mohammad

    2016-06-01

    Ta-Al-N thin films were deposited by cylindrical DC magnetron sputtering on a stainless steel substrate under varying nitrogen flow ratios ( N2 with respect to N2 + Ar in the range of 1.5%-9%. The effect of the N2 content in the reactive gas mixture on crystalline structure, surface morphology, and mechanical properties of Ta-Al-N thin films was investigated. The amount of Al and Ta in deposited films was obtained by energy dispersive X-ray spectroscopy (EDX) analysis and films thickness was measured by surface step profilometer. X-ray diffraction analysis (XRD) revealed that the crystalline structure of the Ta-Al-N polycrystalline thin film is a mixture of TaAl, TaN, and AlN crystalline phases. Surface morphology, roughness, and grain size were investigated by atomic force microscopy (AFM). The nano hardness of Ta-Al-N thin films, measured by the nanoindentation method, was about 9GPa maximum for samples prepared under 3% N2 , and the friction coefficient, obtained by nanoscratch analysis, was approximately 0.2 for all Ta-Al-N thin films. Other results were found to be affected considerably by increasing the N2 amount.

  12. Vehicle Exhaust Gas Clearance by Low Temperature Plasma-Driven Nano-Titanium Dioxide Film Prepared by Radiofrequency Magnetron Sputtering

    PubMed Central

    Yu, Shuang; Liang, Yongdong; Sun, Shujun; Zhang, Kai; Zhang, Jue; Fang, Jing

    2013-01-01

    A novel plasma-driven catalysis (PDC) reactor with special structure was proposed to remove vehicle exhaust gas. The PDC reactor which consisted of three quartz tubes and two copper electrodes was a coaxial dielectric barrier discharge (DBD) reactor. The inner and outer electrodes firmly surrounded the outer surface of the corresponding dielectric barrier layer in a spiral way, respectively. Nano-titanium dioxide (TiO2) film prepared by radiofrequency (RF) magnetron sputtering was coated on the outer wall of the middle quartz tube, separating the catalyst from the high voltage electrode. The spiral electrodes were designed to avoid overheating of microdischarges inside the PDC reactor. Continuous operation tests indicated that stable performance without deterioration of catalytic activity could last for more than 25 h. To verify the effectiveness of the PDC reactor, a non-thermal plasma(NTP) reactor was employed, which has the same structure as the PDC reactor but without the catalyst. The real vehicle exhaust gas was introduced into the PDC reactor and NTP reactor, respectively. After the treatment, compared with the result from NTP, the concentration of HC in the vehicle exhaust gas treated by PDC reactor reduced far more obviously while that of NO decreased only a little. Moreover, this result was explained through optical emission spectrum. The O emission lines can be observed between 870 nm and 960 nm for wavelength in PDC reactor. Together with previous studies, it could be hypothesized that O derived from catalytically O3 destruction by catalyst might make a significant contribution to the much higher HC removal efficiency by PDC reactor. A series of complex chemical reactions caused by the multi-components mixture in real vehicle exhaust reduced NO removal efficiency. A controllable system with a real-time feedback module for the PDC reactor was proposed to further improve the ability of removing real vehicle exhaust gas. PMID:23560062

  13. Co-sputtered metal and polymer nanocomposite films and their electrical responses for gas sensing application

    NASA Astrophysics Data System (ADS)

    Rujisamphan, Nopporn; Murray, Roy E.; Deng, Fei; Supasai, Thidarat

    2016-04-01

    Titanium and polytetrafluoroethylene (Ti-PTFE) nanocomposite thin films were successfully fabricated on glass substrates using a combination of dc and rf magnetron sputtering. When the Ti-PTFE composites were prepared at below the percolation threshold i.e. 27% metal volume filling (F), Ti clusters with the average sizes of 7 ± 2 nm were found. As the Ti content was increased above the percolation threshold (F = 62%), the connecting regions of Ti were formed within the polymer matrix and the electrical property changed rapidly from insulator-like to metal-like properties. The Ti-PTFE composites prepared near the percolation threshold showed the electrical response to different volatile organic compounds (VOCs). The sensitivity significantly depended upon the VOCs concentrations. These composites devices showed the presence of distinct chemical bonds of Csbnd C, Csbnd CF, Csbnd F and CF2 and TiF in TiO2 on the surface as investigated by X-ray photoelectron spectroscopy (XPS) while the surface morphology, characterized by atomic force microscopy (AFM) presented the root mean square (RMS) surface roughness of 13.3 nm. Cross-section transmission electron microscopy (TEM) images of the device revealed Ti clusters dispersed in PTFE matrix with particle sizes varied between 10 nm and 30 nm.

  14. Reducing the impurity incorporation from residual gas by ion bombardment during high vacuum magnetron sputtering

    SciTech Connect

    Rosen, Johanna; Widenkvist, Erika; Larsson, Karin; Kreissig, Ulrich; Mraz, Stanislav; Martinez, Carlos; Music, Denis; Schneider, J. M.

    2006-05-08

    The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O{sub 2}/H{sub 2}O environment. Ar{sup +} with an average kinetic energy of {approx}5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from -15 V (floating potential) to -100 V, the hydrogen content decreased by {approx}70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H{sub 2} formation, and desorption [Rosen et al., J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient.

  15. Hypervelocity atmospheric flight: Real gas flow fields

    NASA Technical Reports Server (NTRS)

    Howe, John T.

    1990-01-01

    Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that were reduced to a relatively compact set of equations of a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-averaged behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equation a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. For hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates, chemical nonequilibrium is considered and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

  16. Hypervelocity atmospheric flight: Real gas flow fields

    NASA Technical Reports Server (NTRS)

    Howe, John T.

    1989-01-01

    Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that have been reduced to a relatively compact set of equations in a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-average behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equations a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. Hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates chemical nonequilibrium is considered, and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

  17. Evolution of flow disturbances in cocurrent gas-liquid flows

    SciTech Connect

    McCready, M.J.

    1992-10-01

    Studies of interfacial waves in horizontal gas-liquid flows, close to neutral stability, suggest that the rate of evolution of the interface may be linked to nonlinear interactions between the fundamental mode and the subharmonic -- even if the subharmonic is linearly stable. The rate of evolution increases as the subharmonic becomes more unstable. A comparison of linear stability techniques used to predict the initial behavior of waves reveals similar predictions of growth rates and almost identical speeds between a two layer laminar Orr-Sommerfeld theory and an Orr-Sommerfeld theory when the effect of the (turbulent) gas flow enters as boundary conditions on the liquid layer. However, there is disagreement at small wavenumbers as to the point at which the growth curve crosses 0. This is a significant problem because longwave disturbances, in our case roll waves, form by growth of (initially) small amplitude waves that have frequencies which are 0.5 to 1 Hz, which is in the range where the two theories disagree about the sign of the growth rate. While nonlinear effects are probably involved in the formation of the peak (at least while its amplitude is small), the linear growth rate must play an important role when the amplitude is small.

  18. Ethylene Trace-gas Techniques for High-speed Flows

    NASA Technical Reports Server (NTRS)

    Davis, David O.; Reichert, Bruce A.

    1994-01-01

    Three applications of the ethylene trace-gas technique to high-speed flows are described: flow-field tracking, air-to-air mixing, and bleed mass-flow measurement. The technique involves injecting a non-reacting gas (ethylene) into the flow field and measuring the concentration distribution in a downstream plane. From the distributions, information about flow development, mixing, and mass-flow rates can be dtermined. The trace-gas apparatus and special considerations for use in high-speed flow are discussed. A description of each application, including uncertainty estimates is followed by a demonstrative example.

  19. Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

    2016-10-01

    The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

  20. Recent developments in gas flow computers

    SciTech Connect

    Finnan, K.L.

    1995-12-01

    The selection of new products is a real advantage to the industry. Although it is more difficult for customers to consider more alternatives. the new products better match the functional requirements and budget limitations encountered, today. In this paper, new developments in a number of technical areas will be discussed. Of course, the reason for all the new product introductions is that the suppliers see large market potential. Due to initiatives which are now {open_quotes}old news,{close_quotes} the industry is installing electronic gas measurement (EG) products at a record pace. A review of these initiatives shows that the major factor has been FERC 636. One common misconception is that the rule requires electronic flow computers. The truth of the matter is that EG is a solution to the information flow needs which fall-out from FERC 636. To run a business, today, a company simply cannot wait the 30 to 45 days it takes to process charts and turn them into flow information, company-wide. Using EG. today`s operations obtain flow information on, at least, a daily basis. Some literally have up-to-the-minute flow information. Actually, FERC 636 accelerated a trend that was already in process. As the industry downsized in the late I 980`s and lost many people to retirement, the younger replacements were far more willing to use electronics in place of the traditional chart recorders. Suppliers at the time also expended much effort selling the EG concept and their uphill battle was beginning to show a good return when FERC 636 came along. Another factor in favor of EG is the environmental hazard of the numerous mercury manometers in the field. This has particularly affected the production business. Areas managed by the BLM have a specific requirement which calls for removal of mercury manometers and most users have opted for electronic devices as replacements. Additional BLM requirements for on-site information also helped the EG cause.

  1. Gas flow characteristics of a time modulated APPJ: the effect of gas heating on flow dynamics

    NASA Astrophysics Data System (ADS)

    Zhang, S.; Sobota, A.; van Veldhuizen, E. M.; Bruggeman, P. J.

    2015-01-01

    This work investigates the flow dynamics of a radio-frequency (RF) non-equilibrium argon atmospheric pressure plasma jet. The RF power is at a frequency of 50 Hz or 20 kHz. Combined flow pattern visualizations (obtained by shadowgraphy) and gas temperature distributions (obtained by Rayleigh scattering) are used to study the formation of transient vortex structures in initial flow field shortly after the plasma is switched on and off in the case of 50 Hz modulation. The transient vortex structures correlate well with observed temperature differences. Experimental results of the fast modulated (20 kHz) plasma jet that does not induce changes of the gas temperature are also presented. The latter result suggests that momentum transfer by ions does not have dominant effect on the flow pattern close to the tube. It is argued that the increased gas temperature and corresponding gas velocity increase at the tube exit due to the plasma heating increases the admixing of surrounding air and reduces the effective potential core length. With increasing plasma power a reduction of the effective potential core length is observed with a minimum length for 5.6 W after which the length extends again. Possible mechanisms related to viscosity effects and ionic momentum transfer are discussed.

  2. Probe measures gas and liquid mass flux in high mass flow ratio two-phase flows

    NASA Technical Reports Server (NTRS)

    Burick, R. J.

    1972-01-01

    Deceleration probe constructed of two concentric tubes with separator inlet operates successfully in flow fields where ratio of droplet flow rate to gas flow rate ranges from 1.0 to 20, and eliminates problems of local flow field disturbances and flooding. Probe is effective tool for characterization of liquid droplet/gas spray fields.

  3. Laboratory measurement and interpretation of nonlinear gas flow in shale

    NASA Astrophysics Data System (ADS)

    Kang, Yili; Chen, Mingjun; Li, Xiangchen; You, Lijun; Yang, Bin

    2015-11-01

    Gas flow mechanisms in shale are urgent to clarify due to the complicated pore structure and low permeability. Core flow experiments were conducted under reservoir net confining stress with samples from the Longmaxi Shale to investigate the characteristics of nonlinear gas flow. Meanwhile, microstructure analyses and gas adsorption experiments are implemented. Experimental results indicate that non-Darcy flow in shale is remarkable and it has a close relationship with pore pressure. It is found that type of gas has a significant influence on permeability measurement and methane is chosen in this work to study the shale gas flow. Gas slippage effect and minimum threshold pressure gradient weaken with the increasing backpressure. It is demonstrated that gas flow regime would be either slip flow or transition flow with certain pore pressure and permeability. Experimental data computations and microstructure analyses confirm that hydraulic radius of flow tubes in shale are mostly less than 100 nm, indicating that there is no micron scale pore or throat which mainly contributes to flow. The results are significant for the study of gas flow in shale, and are beneficial for laboratory investigation of shale permeability.

  4. Effects of N2/O2 flow rate on the surface properties and biocompatibility of nano-structured TiOxNy thin films prepared by high vacuum magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Saleem, Sehrish; Ahmad, R.; Ikhlaq, Uzma; Ayub, R.; Wei, Hong Jin; Rui Zhen, Xu; Peng, Hui Li; Abbas, Khizra; Chu, Paul K.

    2015-07-01

    NiTi shape memory alloys (SMA) have many biomedical applications due to their excellent mechanical and biocompatible properties. However, nickel in the alloy may cause allergic and toxic reactions, which limit some applications. In this work, titanium oxynitride films were deposited on NiTi samples by high vacuum magnetron sputtering for various nitrogen and oxygen gas flow rates. The x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) results reveal the presence of different phases in the titanium oxynitride thin films. Energy dispersive spectroscopy (EDS) elemental mapping of samples after immersion in simulated body fluids (SBF) shows that Ni is depleted from the surface and cell cultures corroborate the enhanced biocompatibility in vitro. Project supported by the Higher Education Commission, Hong Kong Research Grants Council (RGC) General Research Funds (GRF), China (Grant No. 112212) and the City University of Hong Kong Applied Research Grant (ARG), China (Grant No. 9667066).

  5. Computer program for natural gas flow through nozzles

    NASA Technical Reports Server (NTRS)

    Johnson, R. C.

    1972-01-01

    Subroutines, FORTRAN 4 type, were developed for calculating isentropic natural gas mass flow rate through nozzle. Thermodynamic functions covering compressibility, entropy, enthalpy, and specific heat are included.

  6. A Gas-Kinetic Scheme for Reactive Flows

    NASA Technical Reports Server (NTRS)

    Lian,Youg-Sheng; Xu, Kun

    1998-01-01

    In this paper, the gas-kinetic BGK scheme for the compressible flow equations is extended to chemical reactive flow. The mass fraction of the unburnt gas is implemented into the gas kinetic equation by assigning a new internal degree of freedom to the particle distribution function. The new variable can be also used to describe fluid trajectory for the nonreactive flows. Due to the gas-kinetic BGK model, the current scheme basically solves the Navier-Stokes chemical reactive flow equations. Numerical tests validate the accuracy and robustness of the current kinetic method.

  7. Gas flow means for improving efficiency of exhaust hoods

    DOEpatents

    Gadgil, A.J.

    1994-01-11

    Apparatus is described for inhibiting the flow of contaminants in an exhaust enclosure toward an individual located adjacent an opening into the exhaust enclosure by providing a gas flow toward a source of contaminants from a position in front of an individual to urge said contaminants away from the individual toward a gas exit port. The apparatus comprises a gas manifold which may be worn by a person as a vest. The manifold has a series of gas outlets on a front face thereof facing away from the individual and toward the contaminants to thereby provide a flow of gas from the front of the individual toward the contaminants. 15 figures.

  8. Gas flow means for improving efficiency of exhaust hoods

    DOEpatents

    Gadgil, Ashok J.

    1994-01-01

    Apparatus for inhibiting the flow of contaminants in an exhaust enclosure toward an individual located adjacent an opening into the exhaust enclosure by providing a gas flow toward a source of contaminants from a position in front of an individual to urge said contaminants away from the individual toward a gas exit port. The apparatus comprises a gas mani-fold which may be worn by a person as a vest. The manifold has a series of gas outlets on a front face thereof facing away from the individual and toward the contaminants to thereby provide a flow of gas from the front of the individual toward the contaminants.

  9. Simulation of gas particle flow in a HVOF torch

    SciTech Connect

    Chang, C.H.; Moore, R.L.

    1995-12-31

    A transient two-dimensional numerical simulation of Inconel spraying in an HVOF torch barrel has been performed. The gas flow is treated as a continuum multicomponent chemically reacting flow, while particles are modeled using a stochastic particle spray model, fully coupled to the gas flow. The calculated results agree well with experimental data, and show important statistical aspects of particle flow in the torch.

  10. Sputter target

    DOEpatents

    Gates, Willard G.; Hale, Gerald J.

    1980-01-01

    The disclosure relates to an improved sputter target for use in the deposition of hard coatings. An exemplary target is given wherein titanium diboride is brazed to a tantalum backing plate using a gold-palladium-nickel braze alloy.

  11. NMR velocity mapping of gas flow around solid objects.

    PubMed

    Han, Song-I; Pierce, Kimberly L; Pines, Alexander

    2006-07-01

    We present experimental visualizations of gas flow around solid blunt bodies by NMR imaging. NMR velocimetry is a model-free and tracer-free experimental means for quantitative and multi-dimensional flow visualization. Hyperpolarization of (129)Xe provided sufficient NMR signal to overcome the low density of the dilute gas phase, and its long coherence time allows for true velocity vector mapping. In this study, the diverging gas flow around and wake patterns immediately behind a sphere could be vectorally visualized and quantified. In a similar experiment, the flow over an aerodynamic model airplane body revealed a less disrupted flow pattern.

  12. NMR velocity mapping of gas flow around solid objects

    NASA Astrophysics Data System (ADS)

    Han, Song-I.; Pierce, Kimberly L.; Pines, Alexander

    2006-07-01

    We present experimental visualizations of gas flow around solid blunt bodies by NMR imaging. NMR velocimetry is a model-free and tracer-free experimental means for quantitative and multi-dimensional flow visualization. Hyperpolarization of Xe129 provided sufficient NMR signal to overcome the low density of the dilute gas phase, and its long coherence time allows for true velocity vector mapping. In this study, the diverging gas flow around and wake patterns immediately behind a sphere could be vectorally visualized and quantified. In a similar experiment, the flow over an aerodynamic model airplane body revealed a less disrupted flow pattern.

  13. Discharge effects on gas flow dynamics in a plasma jet

    NASA Astrophysics Data System (ADS)

    Xian, Yu Bin; Hasnain Qaisrani, M.; Yue, Yuan Fu; Lu, Xin Pei

    2016-10-01

    Plasma is used as a flow visualization method to display the gas flow of a plasma jet. Using this method, it is found that a discharge in a plasma jet promotes the transition of the gas flow to turbulence. A discharge at intermediate frequency (˜6 kHz in this paper) has a stronger influence on the gas flow than that at lower or higher frequencies. Also, a higher discharge voltage enhances the transition of the gas flow to turbulence. Analysis reveals that pressure modulation induced both by the periodically directed movement of ionized helium and Ohmic heating on the gas flow plays an important role in inducing the transition of the helium flow regime. In addition, since the modulations induced by the high- and low-frequency discharges are determined by the frequency-selective effect, only intermediate-frequency (˜6 kHz) discharges effectively cause the helium flow transition from the laminar to the turbulent flow. Moreover, a discharge with a higher applied voltage makes a stronger impact on the helium flow because it generates stronger modulations. These conclusions are useful in designing cold plasma jets and plasma torches. Moreover, the relationship between the discharge parameters and the gas flow dynamics is a useful reference on active flow control with plasma actuators.

  14. Influence of working gas pressure on structure and properties of WO3 films reactively deposited by rf magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Takahashi, T.; Tanabe, J.; Yamada, N.; Nakabayashi, H.

    2003-07-01

    Tungsten trioxide (WO3) films with thickness of 0.9-6.7 μm have been deposited on glass-slide substrates, using rf magnetron sputtering in an atmosphere of mixture 80% Ar and 20% O2. The as-deposited films had a dark metallic color, like the W target, at a working gas pressure PW of 1 mTorr. Yellow films resulted at a PW of 3 mTorr. With a further increase of PW, the film color changed to pale yellow. From the x-ray diffraction patterns, the as-deposited films were polycrystalline crystallizing in the monoclinic crystal structure with high c-axis orientation perpendicular to the film plane. The optical transmittance of the films deposited at a PW of 1 mTorr is nearly zero. However, the transmittance of the films deposited at other PW are larger than 70% in the wavelength, λ, ranging from 500 to 900 nm. With decreasing λ to 400 nm, the transmittance decreases steeply to zero. The λ at this absorption edge is longer than that in TiO2 and comes in the visible region. The surface morphology of the films depends on PW. This different morphology may be attributed to the effect of the substrate heating by plasma emission because of the high plasma density at higher PW. The morphology of the films may also depend on the crystallinity of the WO3 films. As PW increased, the surfaces of the films became rougher but the grain sizes of the films did not always become larger. The WO3 films deposited in this study may be used for the underlayer of TiO2 photocatalyst.

  15. Unconventional Shale-Gas Resource Systems and Processes Affecting Gas Generation, Retention, Storage, and Flow Rates

    NASA Astrophysics Data System (ADS)

    Jarvie, D. M.; Philp, R. P.; Jarvie, B. M.

    2009-04-01

    Geochemical and petrophysical characterization of various shale-gas systems in the U.S. indicates a variety of unconventional shale-gas system types. The most basic distinction is gas type: biogenic and thermogenic, although there can also be mixtures of the two gas types. Thermogenic shale-gas systems are further segregated into various sub-types depending on geochemistry and geology. The shale-gas system categories are: (1) high thermal maturity shale; (2) low thermal maturity shales; (3) mixed lithology intra-formational systems containing shale, sands, and silts; (4) inter-formational systems where gas is generated in a mature shale and stored in a less mature shale, and (5) mixed systems. A key difference among these shale-gas systems are initial gas flow rates. High thermal maturity systems tend to have much higher gas flow rates than low maturity systems because of gas charge and storage mechanisms. Certainly other non-geochemical factors, such as shale mineralogy, are extremely important in being able to stimulate these shales to flow gas. Geochemical comparison of the Antrim Shale (Michigan Basin), New Albany Shale (Illinois Basin), and Barnett Shale (Fort Worth Basin) are used to illustrate these different systems as well as other systems. These systems show significant differences in gas type, organic richness, thermal maturity, and gas flow rates. Gas flow rates are then dependent upon the amount of gas stored (or generated) and the ability to release gas from adsorption sites as well as connecting to micro-reservoir compartments.

  16. A model for predicting laminar gas flow through micropassages

    NASA Astrophysics Data System (ADS)

    Li, Jun-Ming; Wang, Bu-Xuan; Peng, Xiao-Feng

    1997-12-01

    An theoretical investigation was conducted to detect the gas-solid interface effect on laminar flow characteristics for gas flowing through micropassages. In the wall-adjacent region, the change in viscosity of fluid vs the distance from the wall surface, as derived from the kinetic theory of gases result in significant influence on the flow characteristics in micropassages. A model was proposed to account for the wall effect. Analytical expressions for velocity profiles and pressure drop were derived, respectively, for laminar flow of gases in microtubes and in extremely narrow parallel plates. The Knudsen number, Kn, as a criterion, that the flow can be treated reasonably as flow in macrochannels, is discussed.

  17. 21 CFR 868.2885 - Gas flow transducer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas flow transducer. 868.2885 Section 868.2885 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2885 Gas flow transducer....

  18. 21 CFR 868.2885 - Gas flow transducer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gas flow transducer. 868.2885 Section 868.2885 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Monitoring Devices § 868.2885 Gas flow transducer....

  19. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Raw exhaust gas flow. 89.416 Section 89.416 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION ENGINES Exhaust Emission Test Procedures § 89.416 Raw exhaust gas flow....

  20. Device accurately measures and records low gas-flow rates

    NASA Technical Reports Server (NTRS)

    Branum, L. W.

    1966-01-01

    Free-floating piston in a vertical column accurately measures and records low gas-flow rates. The system may be calibrated, using an adjustable flow-rate gas supply, a low pressure gage, and a sequence recorder. From the calibration rates, a nomograph may be made for easy reduction. Temperature correction may be added for further accuracy.

  1. Gas/liquid flow measurement using coriolis-based flow meters

    SciTech Connect

    Liu, K.T.; Nguyen, T.V.

    1991-07-09

    This patent describes a method of determining total mass flow rate and phase distribution of individual components in a flowing gas/liquid stream. It comprises flowing at least a first gas/liquid stream through a Coriolis-based flow meter, the first gas/liquid stream having a first known total mass flow rate and component phase distribution; obtaining a first apparent total mass flow rate output and a first apparent density output from the Coriolis- based mass flow meter; correlating the first known total mass flow rate and phase distribution with the first apparent mass flow rate output and the first apparent density output obtained from the Coriolis-based mass flow meter to determine a set of correlation equations; flowing a second gas/liquid stream through the Coriolis-based mass flow meter; obtaining a second apparent mass flow rate output and a second apparent density output from the Coriolis-based mass flow meter; calculating a total mass flow rate and a component phase distribution of the second gas/liquid stream based on the correlation equations and the second apparent mass flow rate output and the second apparent density output.

  2. Real-Time Measurement of Vehicle Exhaust Gas Flow

    SciTech Connect

    Hardy, J.E.; Hylton, J.O.; Joy, R.D.; McKnight, T.E.

    1999-06-28

    A flow measurement system was developed to measure, in real-time, the exhaust gas flow from vehicies. This new system was based on the vortex shedding principle using ultrasonic detectors for sensing the shed vortices. The flow meter was designed to measure flow over a range of 1 to 366 Ips with an inaccuracy of ~1o/0 of reading. Additionally, the meter was engineered to cause minimal pressure drop (less than 125mm of water), to function in a high temperature environment (up to 650oC) with thermal transients of 15 oC/s, and to have a response time of 0.1 seconds for a 10% to 90!40 step change. The flow meter was also configured to measure hi-directional flow. Several flow meter prototypes were fabricated, tested, and calibrated in air, simulated exhaust gas, and actual exhaust gas. Testing included gas temperatures to 600oC, step response experiments, and flow rates from O to 360 lps in air and exhaust gas. Two prototypes have been tested extensively at NIST and two additional meters have been installed in exhaust gas flow lines for over one year. This new flow meter design has shown to be accurate, durabIe, fast responding, and to have a wide rangeabi~ity.

  3. Thermoacoustic compression based on alternating to direct gas flow conversion

    NASA Astrophysics Data System (ADS)

    Sun, D. M.; Wang, K.; Xu, Y.; Shen, Q.; Zhang, X. J.; Qiu, L. M.

    2012-05-01

    We present a remarkable thermoacoustically driven compression effect based on the conversion of gas flow from an alternating state to a direct state. The alternating gas flow is generated by the thermoacoustic effect in thermoacoustic engines, whereas direct gas flow is achieved by means of the flow rectification effect of check valves. A demonstrative thermoacoustic compressor consisting of two standing-wave thermoacoustic engines, two reservoirs, and three check valves is constructed for experimental investigation. With nitrogen as a working gas and an initial pressure of 2.4 MPa in all components, a usable pressure difference of 0.4 MPa is achieved, with the average gas pumping rate reaching 2.85 Nm3/h during the first 3 s of the compression process. The simple mechanical structure and thermally driven nature of the compressor show potential in gas compression, power generation, and refrigeration applications.

  4. Transit time ultrasonic flow meters for natural gas measurement

    SciTech Connect

    Upp, E.L.; Warner, K.L.

    1996-12-31

    Transit-time ultrasonic flow meters for gas have gained a larger acceptance within the natural gas industry in recent years, and are now an option for custody transfer metering in several countries. Additionally, there are several varieties of less expensive transit-time ultrasonic flow meters which are excellent in check metering applications although limited in accuracy. The proper choice of ultrasonic flow meter normally depends on the absolute accuracy required, with the multipath configuration offering the best accuracy. Ultrasonic flow meters must be properly installed and the natural gas must be of good quality to achieve an accurate measurement, as with any type of gas flow meter. As experience grows within the measurement community, the use and applications for transit-time ultrasonic flow meters may expand greatly.

  5. Modelling and analysis of sputter deposited ZrN coating by CFD

    NASA Astrophysics Data System (ADS)

    Kapopara, Jaydeep M.; Mengar, Akshaykumar R.; Chauhan, Kamlesh V.; Patel, Nicky P.; Rawal, Sushant K.

    2016-09-01

    The objective of the present work is to investigate the effect of various sputtering parameters such as velocity, mass flow rate on velocity profiles, pressure profiles, density profiles and concentration distribution of the process gases (argon and nitrogen) of zirconium nitride films deposited on glass and silica substrate by RF magnetron sputtering. A three dimensional Computational Fluid Dynamics (CFD) study has been carried out using Fluent-ANSYS commercial code to visualize the mixing behavior of process gases inside the deposition chamber. The results show that the location of gas inlet port has a greater influence on gas distribution inside the chamber where reactive gas will form coating. By having this information, one can able to modify the reactor geometry and gas flow openings along with its positions for better gas flow over the substrate which in turns gives an indirect indication of coating from the composition point of view.

  6. Optimization of gas hydrate reactors with slug flow

    SciTech Connect

    Elperin, T.; Fominykh, A.

    1997-11-01

    A model of heat transfer during gas hydrate formation at a gas-liquid interface in gas-liquid slug flow with liquid plugs containing small bubbles is suggested. Under the assumption of perfect mixing of liquid in liquid plugs, recurrent relations for temperature in the n-th liquid plug and heat and mass fluxes from the n-th unit cell in a gas-liquid slug flow are derived. The ratio of the total mass flux during gas hydrate formation in a cluster with N unit cells to the mass flux in a cluster with an infinite number of unit cells is determined. The number of unit cells that yield 95% of the total amount of gas hydrates in an infinite cluster of unit cells is calculated and formula for an optimal length of a gas hydrate slug flow reactor is derived.

  7. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    NASA Astrophysics Data System (ADS)

    Kavitha, A.; Subramanian, N. Sankara; Loganathan, S.; Kannan, R.

    2014-04-01

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  8. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    SciTech Connect

    Kavitha, A.; Kannan, R.; Subramanian, N. Sankara; Loganathan, S.

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  9. Flow shaping using three-dimensional microscale gas discharge

    SciTech Connect

    Wang, C.-C.; Roy, Subrata

    2009-08-24

    We introduce a flow shaping mechanism using surface compliant microscale gas discharge. A three-dimensional finite element-based multiscale ionized gas flow code is utilized to analyze charge separation, potential distribution, and flow inducement mechanism. For the case of quiescent flow, a horseshoe-shaped plasma generator is introduced. Due to its unusual shape, the three-dimensional electric force excites a pinching effect on the fluid inside selectively powered electrode arc. Such effect is capable of tripping the flow-ejecting fluid normal to the plane of the actuator and thus can be very useful for many applications.

  10. Breakup of Droplets in an Accelerating Gas Flow

    NASA Technical Reports Server (NTRS)

    Dickerson, R. A.; Coultas, T. A.

    1966-01-01

    A study of droplet breakup phenomena by an accelerating gas flow is described. The phenomena are similar to what propellant droplets experience when exposed to accelerating combustion gas flow in a rocket engine combustion zone. Groups of several dozen droplets in the 100-10 750-micron-diameter range were injected into a flowing inert gas in a transparent rectangular nozzle. Motion photography of the behavior of the droplets at various locations in the accelerating gas flow has supplied quantitative and qualitative data on the breakup phenomena which occur under conditions similar to those found in large rocket engine combustors. A blowgun injection device, used to inject very small amounts of liquid at velocities of several hundred feet per second into a moving gas stream, is described. The injection device was used to inject small amounts of liquid RP-1 and water into the gas stream at a velocity essentially equal to the gas velocity where the group of droplets was allowed to stabilize its formation in a constant area section before entering the convergent section of the transparent nozzle. Favorable comparison with the work of previous investigators who have used nonaccelerating gas flow is found with the data obtained from this study with accelerating gas flow. The criterion for the conditions of minimum severity required to produce shear-type droplet breakup in an accelerating gas flow is found to agree well with the criterion previously established at Rocketdyne for breakup in nonaccelerating flow. An extension of the theory of capillary surface wave effects during droplet breakup is also presented. Capillary surface waves propagating in the surface of the droplet, according to classical hydrodynamical laws, are considered. The waves propagate tangentially over the surface of the droplet from the forward stagnation point to the major diameter. Consideration of the effects of relative gas velocity on the amplitude growth of these waves allows conclusions to be

  11. Modeling target erosion during reactive sputtering

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Depla, D.

    2015-03-01

    The influence of the reactive sputter conditions on the racetrack and the sputter profile for an Al/O2 DC reactive sputter system is studied by modeling. The role of redeposition, i.e. the deposition of sputtered material back on the target, is therefore taken into account. The used model RSD2013 is capable of simulating the effect of redeposition on the target condition in a spatial resolved way. Comparison between including and excluding redeposition in the RSD2013 model shows that the in-depth oxidation profile of the target differs. Modeling shows that it is important to distinguish between the formed racetrack, i.e. the erosion depth profile, and the sputter profile. The latter defines the distribution of the sputtered atoms in the vacuum chamber. As the target condition defines the sputter yield, it does determine the racetrack and the sputter profile of the planar circular target. Both the shape of the racetrack and the sputter profile change as function of the redeposition fraction as well as function of the oxygen flow change. Clear asymmetries and narrowing are observed for the racetrack shape. Similar effects are noticed for the sputter profile but to a different extent. Based on this study, the often heard misconception that the racetrack shape defines the distribution of the sputtered atoms during reactive sputtering is proven to be wrong.

  12. Reactive sputter deposition of boron nitride

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; McKernan, M.A.; Makowiecki, D.M.

    1995-10-01

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied {minus}300 V dc bias.

  13. Gas flow driven by thermal creep in dusty plasma

    SciTech Connect

    Flanagan, T. M.; Goree, J.

    2009-10-15

    Thermal creep flow (TCF) is a flow of gas driven by a temperature gradient along a solid boundary. Here, TCF is demonstrated experimentally in a dusty plasma. Stripes on a glass box are heated by laser beam absorption, leading to both TCF and a thermophoretic force. The design of the experiment allows isolating the effect of TCF. A stirring motion of the dust particle suspension is observed. By eliminating all other explanations for this motion, we conclude that TCF at the boundary couples by drag to the bulk gas, causing the bulk gas to flow, thereby stirring the suspension of dust particles. This result provides an experimental verification, for the field of fluid mechanics, that TCF in the slip-flow regime causes steady-state gas flow in a confined volume.

  14. New technology directly measures mass flow of gas

    SciTech Connect

    Hahn, D.T.

    1995-12-31

    According to recent industry surveys and solicitations by organizations such as the Gas Research Institute and Small Business Innovation Research, a need exists for a gas flowmeter with {plus_minus}0.5% or better accuracy, that does not need to be calibrated for specific gas properties, and requires no periodic maintenance. Over the past 18 years, Coriolis mass flowmeters have provided these features for liquid flow applications, and have won a significant share of the liquid flow measurement market. Coriolis meters continue to be the fastest growing technology in the world market for flow measurement. Coriolis mass flowmeters have not, however, had much success in penetrating the gas flow measurement market due to some limitations involved with measuring the low density fluids associated with low pressure gas flow measurement. A new type of Coriolis mass flowmeter has been developed which utilizes a unique new method of creating and measuring the requisite Coriolis forces. This new technology; radial mode Coriolis mass flow measurement, has several inherent features that make it perfectly suited to measuring the mass flow of gas.

  15. Rare gas flow structuration in plasma jet experiments

    NASA Astrophysics Data System (ADS)

    Robert, E.; Sarron, V.; Darny, T.; Riès, D.; Dozias, S.; Fontane, J.; Joly, L.; Pouvesle, J.-M.

    2014-02-01

    Modifications of rare gas flow by plasma generated with a plasma gun (PG) are evidenced through simultaneous time-resolved ICCD imaging and schlieren visualization. The geometrical features of the capillary inside which plasma propagates before in-air expansion, the pulse repetition rate and the presence of a metallic target are playing a key role on the rare gas flow at the outlet of the capillary when the plasma is switched on. In addition to the previously reported upstream offset of the laminar to turbulent transition, we document the reverse action leading to the generation of long plumes at moderate gas flow rates together with the channeling of helium flow under various discharge conditions. For higher gas flow rates, in the l min-1 range, time-resolved diagnostics performed during the first tens of ms after the PG is turned on, evidence that the plasma plume does not start expanding in a laminar neutral gas flow. Instead, plasma ignition leads to a gradual laminar-like flow build-up inside which the plasma plume is generated. The impact of such phenomena for gas delivery on targets mimicking biological samples is emphasized, as well as their consequences on the production and diagnostics of reactive species.

  16. Gas/oil/water flow measurement by electrical capacitance tomography

    NASA Astrophysics Data System (ADS)

    Li, Yi; Yang, Wuqiang; Xie, Cheng-gang; Huang, Songming; Wu, Zhipeng; Tsamakis, Dimitrios; Lenn, Chris

    2013-07-01

    In the oil industry, it is important to measure gas/oil/water flows produced from oil wells. To determine oil production, it is necessary to measure the water-in-liquid ratio (WLR), liquid fraction and some other parameters, which are related to multiphase flow rates. A research team from the University of Manchester and Schlumberger Gould Research have developed an experimental apparatus for gas/oil/water flow measurement based on a flow-conditioning device and electrical capacitance tomography (ECT) and microwave sensors. This paper presents the ECT part of the developed apparatus, including the re-engineering of an ECT sensor and a model-based image reconstruction algorithm, which is used to derive the WLR and the thickness of the liquid layer in oil-continuous annular flows formed by the flow-conditioning device. The ECT sensor was tested both at Schlumberger and on TUV-NEL's Multiphase Flow Facility. The experimental results are promising.

  17. Gas flow analysis in melting furnaces

    SciTech Connect

    Kiss, L.I.; Bui, R.T.; Charette, A.; Bourgeois, T.

    1998-12-01

    The flow structure inside round furnaces with various numbers of burners, burner arrangement, and exit conditions has been studied experimentally with the purpose of improving the flow conditions and the resulting heat transfer. Small-scale transparent models were built according to the laws of geometric and dynamic similarity. Various visualization and experimental techniques were applied. The flow pattern in the near-surface regions was visualized by the fluorescent minituft and popcorn techniques; the flow structure in the bulk was analyzed by smoke injection and laser sheet illumination. For the study of the transient effects, high-speed video photography was applied. The effects of the various flow patterns, like axisymmetric and rotational flow, on the magnitude and uniformity of the residence time, as well as on the formation of stagnation zones, were discussed. Conclusions were drawn and have since been applied for the improvement of furnace performance.

  18. Flow instability and bifurcation in gas-loaded reflux thermosyphons

    NASA Astrophysics Data System (ADS)

    Peterson, P. F.; Tien, C. L.; Lee, K. W.; Elkouh, N.

    1991-02-01

    In vertical gas-loaded two-phase reflux thermosyphons, the temperature and concentration gradients between the active and shut-off regions can create double-diffusive mixed convection flows. When the noncondensable gas molecular weight is greater than that of the vapor, different steady and time-dependent gas recirculation patterns develop, similar to those observed during Rayleigh-Benard convection in vertical slots. Experimental results presented here show that bifurcations from axisymmetric to three-dimensional, then asymmetric, and finally multiple distinct gas-flow patterns occur as the Rayleigh number increases. Ultimately, a sudden transition to a large-amplitude oscillatory gas flow takes place. Detailed concentration maps and power-density spectra from point wet-bulb temperature measurements clearly chart these transitions. These results impact the design of many condensing systems where noncondensables are present.

  19. Heat flow anomalies in oil- and gas-bearing structures

    SciTech Connect

    Sergiyenko, S.I.

    1988-02-01

    The main features of the distribution of heat flow values in oil, gas and gas-condensate fields on the continents have been discussed by Makarenko and Sergiyenko. The method of analysis used made it possible to establish that the presence of hydrocarbons in formations leads to high heat-flow, regardless of the age of folding of the potentially oil- and gas-bearing zones. Only in regions adjacent to marginal Cenozoic folded mountain structures and in zones of Cenozoic volcanism is the world average higher, by 2.5 to 10%, than in the oil- and gas-bearing structures in those regions. The earlier analysis of the distribution of heat flow values in oil and gas structures was based on 403 measurements. The author now has nearly doubled the sample population, enabling him substantially to revise the ideas on the distribution of heat flow values and the development of the thermal regime of local oil and gas structures. He notes that the method previously used, comparing heat flow values on young continental platforms with values in local oil and gas structures, makes it possible to estimate the thermal effect of the presence of oil and gas. This conclusion stems from the fact that the overwhelming majority of heat flow measurements were made on various kinds of positive structural forms, and distortions of the thermal field caused by thermal anisotropy phenomena are equally characteristic of both productive and nonproductive structures. As a result, for the first time a continuous time series of heat flow measurements over oil and gas structures in various tectonic regions, with ages of consolidation ranging from the Precambrian to the Cenozoic, was established. 26 references.

  20. Freely Localized Microwave Discharge in a Supersonic Gas Flow

    SciTech Connect

    Shibkov, V.M.; Aleksandrov, A.F.; Ershov, A.P.; Timofeev, I.B.; Chernikov, V.A.; Shibkova, L.V.

    2005-09-15

    A discharge produced by a focused microwave beam in a supersonic gas flow has been investigated experimentally. It is shown that the degree of ionization and the gas temperature in the discharge are fairly high and that the main properties of the discharge plasma are only slightly affected by the supersonic air flow. Discharges produced by focused microwave beams can find application in supersonic plasma aerodynamics.

  1. Flowing gas, non-nuclear experiments on the gas core reactor

    NASA Technical Reports Server (NTRS)

    Kunze, J. F.; Cooper, C. G.; Macbeth, P. J.

    1973-01-01

    Variations in cavity wall and injection configurations of the gas core reactor were aimed at establishing flow patterns that give a maximum of the nuclear criticality eigenvalue. Correlation with the nuclear effect was made using multigroup diffusion theory normalized by previous benchmark critical experiments. Air was used to simulate the hydrogen propellant in the flow tests, and smoked air, argon, or Freon to simulate the central nuclear fuel gas. Tests were run both in the down-firing and upfiring directions. Results showed that acceptable flow patterns with volume fraction for the simulated nuclear fuel gas and high flow rate ratios of propellant to fuel can be obtained. Using a point injector for the fuel, good flow patterns are obtained by directing the outer gas at high velocity long the cavity wall, using louvered injection schemes. Recirculation patterns were needed to stabilize the heavy central gas when different gases are used.

  2. Gas Bubble Formation in Stagnant and Flowing Mercury

    SciTech Connect

    Wendel, Mark W; Abdou, Ashraf A; Riemer, Bernie; Felde, David K

    2007-01-01

    Investigations in the area of two-phase flow at the Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS) facility are progressing. It is expected that the target vessel lifetime could be extended by introducing gas into the liquid mercury target. As part of an effort to validate the two-phase computational fluid dynamics (CFD) model, simulations and experiments of gas injection in stagnant and flowing mercury have been completed. The volume of fluid (VOF) method as implemented in ANSYS-CFX, was used to simulate the unsteady two-phase flow of gas injection into stagnant mercury. Bubbles produced at the upwards-oriented vertical gas injector were measured with proton radiography at the Los Alamos Neutron Science Center. The comparison of the CFD results to the radiographic images shows good agreement for bubble sizes and shapes at various stages of the bubble growth, detachment, and gravitational rise. Although several gas flows were measured, this paper focuses on the case with a gas flow rate of 8 cc/min through the 100-micron-diameter injector needle. The acoustic waves emitted due to the detachment of the bubble and during subsequent bubble oscillations were recorded with a microphone, providing a precise measurement of the bubble sizes. As the mercury flow rate increases, the drag force causes earlier bubble detachment and therefore smaller bubbles.

  3. Gas flow dependence of atmospheric pressure plasma needle discharge characteristics

    NASA Astrophysics Data System (ADS)

    Qian, Muyang; Yang, Congying; Liu, Sanqiu; Chen, Xiaochang; Ni, Gengsong; Wang, Dezhen

    2016-04-01

    In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m-3 at 10 ns in our work.

  4. On mechanisms of choked gas flows in microchannels

    NASA Astrophysics Data System (ADS)

    Shan, Xiaodong; Wang, Moran

    2015-10-01

    Choked gas flows in microchannels have been reported before based solely on experimental measurements, but the underlining physical mechanism has yet to be clarified. In this work, we are to explore the process via numerical modeling of choked gas flows through a straight microchannel that connects two gas reservoirs. The major theoretical consideration lies in that, since the gas in microchannels may not be necessarily rarefied even at a high Knudsen number, a generalized Monte Carlo method based on the Enskog theory, GEMC, was thus used instead of direct simulation Monte Carlo (DSMC). Our results indicate that the choked gas flows in microchannels can be divided into two types: sonic choking and subsonic choking, because the sonic point does not always exist even though the gas flows appear choked, depending on the inlet-outlet pressure ratio and the length-height ratio of the channel. Even if the gas flow does not reach a sonic point at the outlet region, the effective pressure ratio (pi /po) acting on the channel becomes asymptotically changeless when the pressure ratio on the buffer regions (pi‧/po‧) is higher than a certain value. The subsonic choking may caused by the expansion wave or the strong non-equilibrium effect at the outlet.

  5. Static gas analysis by a transient flow technique

    SciTech Connect

    Leckey, J.H.; Boeckmann, M.D.

    1988-07-01

    A technique is presented for using a residual gas analyzer (RGA) to analyze small concentrations of heavy gases in lighter gases in a static volume of <10 cm/sup 3/ . Passing the gas sample through a control valve causes it to enter the RGA chamber in molecular flow. This procedure results in fractionation that causes enrichment of the heavier gas during the evacuation of the sample, giving rise to a significantly higher heavy gas signal near the end of the evacuation, while maintaining low pressures in the RGA chamber that are required for linearity. This heavy gas enrichment near the end of the evacuation results in a significant reduction in its detection limit. Specific examples are presented for the analysis of argon in hydrogen and are compared to a gas-flow model of the system.

  6. System for controlling the flow of gas into and out of a gas laser

    DOEpatents

    Alger, Terry; Uhlich, Dennis M.; Benett, William J.; Ault, Earl R.

    1994-01-01

    A modularized system for controlling the gas pressure within a copper vapor or like laser is described herein. This system includes a gas input assembly which serves to direct gas into the laser in a controlled manner in response to the pressure therein for maintaining the laser pressure at a particular value, for example 40 torr. The system also includes a gas output assembly including a vacuum pump and a capillary tube arrangement which operates within both a viscous flow region and a molecular flow region for drawing gas out of the laser in a controlled manner.

  7. Flammable gas interlock spoolpiece flow response test plan and procedure

    SciTech Connect

    Schneider, T.C., Fluor Daniel Hanford

    1997-02-13

    The purpose of this test plan and procedure is to test the Whittaker electrochemical cell and the Sierra Monitor Corp. flammable gas monitors in a simulated field flow configuration. The sensors are used on the Rotary Mode Core Sampling (RMCS) Flammable Gas Interlock (FGI), to detect flammable gases, including hydrogen and teminate the core sampling activity at a predetermined concentration level.

  8. 10. Photograph of a line drawing. 'PROCESS FLOW SCHEMATIC, GAS ...

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

    10. Photograph of a line drawing. 'PROCESS FLOW SCHEMATIC, GAS PRODUCER PROCESS, BUILDING 10A.' Holston Army Ammunition Plant, Holston Defense Corporation. August 29, 1974. Delineator: G. A. Horne. Drawing # SK-1942. - Holston Army Ammunition Plant, Producer Gas Plant, Kingsport, Sullivan County, TN

  9. Using the Multipole Resonance Probe to Stabilize the Electron Density During a Reactive Sputter Process

    NASA Astrophysics Data System (ADS)

    Oberberg, Moritz; Styrnoll, Tim; Ries, Stefan; Bienholz, Stefan; Awakowicz, Peter

    2015-09-01

    Reactive sputter processes are used for the deposition of hard, wear-resistant and non-corrosive ceramic layers such as aluminum oxide (Al2O3) . A well known problem is target poisoning at high reactive gas flows, which results from the reaction of the reactive gas with the metal target. Consequently, the sputter rate decreases and secondary electron emission increases. Both parameters show a non-linear hysteresis behavior as a function of the reactive gas flow and this leads to process instabilities. This work presents a new control method of Al2O3 deposition in a multiple frequency CCP (MFCCP) based on plasma parameters. Until today, process controls use parameters such as spectral line intensities of sputtered metal as an indicator for the sputter rate. A coupling between plasma and substrate is not considered. The control system in this work uses a new plasma diagnostic method: The multipole resonance probe (MRP) measures plasma parameters such as electron density by analyzing a typical resonance frequency of the system response. This concept combines target processes and plasma effects and directly controls the sputter source instead of the resulting target parameters.

  10. Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

    NASA Astrophysics Data System (ADS)

    Masson, R.; Trenty, L.; Zhang, Y.

    2016-09-01

    This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov-Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the mass exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.

  11. Driver gas flow with fluctuations. [shock tube turbulent bursts

    NASA Technical Reports Server (NTRS)

    Johnson, J. A., III; Jones, W. R.; Santiago, J.

    1980-01-01

    A shock tube's driver gas can apparently provide flow with turbulent bursts. The fluctuations are interpreted using a boundary layer model of contact surface flow and results form a kinetic theory of turbulence. With this, a lower limit of 4 on the ratio of maximum to minimum turbulent intensities in contact surface instabilities has been estimated.

  12. Effect of O{sub 2} flow ratio on the microstructure and stress of room temperature reactively sputtered RuO{sub x} thin films

    SciTech Connect

    Shi Junxia; Huang Feng; Weaver, Mark L.; Klein, Tonya M.

    2005-05-01

    RuO{sub x} thin films were deposited at room temperature by reactive radio frequency magnetron-sputtering using Ar/O{sub 2} discharges of varying O{sub 2} flow ratio (f{sub O{sub 2}}) over the range 10%-50% and were characterized using x-ray diffraction, x-ray reflectivity, x-ray photoelectron spectroscopy, resistivity, and stress-temperature measurements. With the increase of f{sub O{sub 2}}, the film texture changed from (110) to (101). Films deposited with f{sub O{sub 2}}>25% were determined stoichiometric. The residual stresses in as-deposited films were all compressive and increased with addition of O{sub 2}, except for the film sputtered at f{sub O{sub 2}}=20% which was in biaxial tension. The film deposited at f{sub O{sub 2}}=30% had a low resistivity value of 68 {mu}{omega} cm and near zero stress (<50 MPa tensile) after a thermal cycle in air up to 500 deg. C which is promising for use in microdevices.

  13. Progress in Creating Stabilized Gas Layers in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Felde, David K; Riemer, Bernie; Abdou, Ashraf A; D'Urso, Brian R; West, David L

    2009-01-01

    The Spallation Neutron Source (SNS) facility in Oak Ridge, Tennessee uses a liquid mercury target that is bombarded with protons to produce a pulsed neutron beam for materials research and development. In order to mitigate expected cavitation damage erosion (CDE) of the containment vessel, a two-phase flow arrangement of the target has been proposed and was earlier proven to be effective in significantly reducing CDE in non-prototypical target bodies. This arrangement involves covering the beam "window", through which the high-energy proton beam passes, with a protective layer of gas. The difficulty lies in establishing a stable gas/liquid interface that is oriented vertically with the window and holds up to the strong buoyancy force and the turbulent mercury flow field. Three approaches to establishing the gas wall have been investigated in isothermal mercury/gas testing on a prototypical geometry and flow: (1) free gas layer approach, (2) porous wall approach, and (3) surface-modified approach. The latter two of these approaches show success in that a stabilized gas layer is produced. Both of these successful approaches capitalize on the high surface energy of liquid mercury by increasing the surface area of the solid wall, thus increasing gas hold up at the wall. In this paper, a summary of these experiments and findings is presented as well as a description of the path forward toward incorporating the stabilized gas layer approach into a feasible gas/mercury SNS target design.

  14. Influence of Oxygen Gas Ratio on the Properties of Aluminum-Doped Zinc Oxide Films Prepared by Radio Frequency Magnetron Sputtering.

    PubMed

    Kim, Minha; Jang, Yong-Jun; Jung, Ho-Sung; Song, Woochang; Kang, Hyunil; Kim, Eung Kwon; Kim, Donguk; Yi, Junsin; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition.

  15. Influence of Oxygen Gas Ratio on the Properties of Aluminum-Doped Zinc Oxide Films Prepared by Radio Frequency Magnetron Sputtering.

    PubMed

    Kim, Minha; Jang, Yong-Jun; Jung, Ho-Sung; Song, Woochang; Kang, Hyunil; Kim, Eung Kwon; Kim, Donguk; Yi, Junsin; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition. PMID:27483888

  16. Ways of intensifying liquid dispersion in gas flow

    NASA Astrophysics Data System (ADS)

    Bazarov, V. G.

    Ways of intensifying liquid dispersion in gas flow are examined with a view to increasing the efficiency of the existing atomizing nozzles. It is noted that the most economical method of dispersion intensification, without using any additional power, is the excitation of auto-oscillations in liquid and gas flows. Several methods of generating auto-oscillations in commonly used centrifugal nozzles are discussed. Other developments include the spraying of viscous and contaminated fluids in a field of forced pressure, velocity, and vorticity fluctuations, and also gas saturation of liquids prior to spraying in nozzles with porous elements.

  17. DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS

    SciTech Connect

    X. Wang; X. Sun; H. Zhao

    2011-09-01

    In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do not exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the applications in

  18. Equations and simulations for multiphase compressible gas-dust flows

    NASA Astrophysics Data System (ADS)

    Oran, Elaine; Houim, Ryan

    2014-11-01

    Dust-gas multiphase flows are important in physical scenarios such as dust explosions in coal mines, asteroid impact disturbing lunar regolith, and soft aircraft landings dispersing desert or beach sand. In these cases, the gas flow regime can range from highly subsonic and nearly incompressible to supersonic and shock-laden flow, the grain packing can range from fully packed to completely dispersed, and both the gas and the dust can range from chemically inert to highly exothermic. To cover the necessary parameter range in a single model, we solve coupled sets of Navier-Stokes equations describing the background gas and the dust. As an example, a reactive-dust explosion that results in a type of shock-flame complex is described and discussed. Sponsored by the University of Maryland through Minta Martin Endowment Funds in the Department of Aerospace Engineering, and through the Glenn L. Martin Institute Chaired Professorship at the A. James Clark School of Engineering.

  19. Hot gas cross flow filtering module

    DOEpatents

    Lippert, Thomas E.; Ciliberti, David F.

    1988-01-01

    A filter module for use in filtering particulates from a high temperature gas has a central gas duct and at least one horizontally extending support mount affixed to the duct. The support mount supports a filter element thereon and has a chamber therein, which communicates with an inner space of the duct through an opening in the wall of the duct, and which communicates with the clean gas face of the filter element. The filter element is secured to the support mount over an opening in the top wall of the support mount, with releasable securement provided to enable replacement of the filter element when desired. Ceramic springs may be used in connection with the filter module either to secure a filter element to a support mount or to prevent delamination of the filter element during blowback.

  20. Gas-Particle Interactions in a Microgravity Flow Cell

    NASA Technical Reports Server (NTRS)

    Louge, Michel; Jenkins, James

    1999-01-01

    We are developing a microgravity flow cell in which to study the interaction of a flowing gas with relatively massive particles that collide with each other and with the moving boundaries of the cell. The absence of gravity makes possible the independent control of the relative motion of the boundaries and the flow of the gas. The cell will permit gas-particle interactions to be studied over the entire range of flow conditions over which the mixture is not turbulent. Within this range, we shall characterize the viscous dissipation of the energy of the particle fluctuations, measure the influence of particle-phase viscosity on the pressure drop along the cell, and observe the development of localized inhomogeneities that are likely to be associated with the onset of clusters. These measurements and observations should contribute to an understanding of the essential physics of pneumatic transport.

  1. Real life experience with multipath ultrasonic gas flow meters

    SciTech Connect

    Sakariassen, R.

    1996-12-31

    Multipath ultrasonic gas flow meters are to be considered as newcomers among flow meters for large, high pressure gas flows. Although the advantages of this type of meters are many and obvious, the metering community is still hesitating to go for it mainly because of lack of experience. The objective of this paper is to present the experience of Statoil after more than six years experience with multipath ultrasonic gas flow meters. Their experience includes laboratory testing and operation in the field for a variety of designs and dimensions. This paper presents the accuracy achieved by such meters including comparison between ultrasonic meters and orifice metering systems in operation, the unique possibilities that this type of meter offers for on-line verification of performance and installation effects. Of particular interest should be noted that in the vicinity of low-noise control valves, such meters could stop functioning completely if no precautions are taken.

  2. Lagrangian solution of supersonic real gas flows

    NASA Technical Reports Server (NTRS)

    Loh, Ching-Yuen; Liou, Meng-Sing

    1993-01-01

    The present extention of a Lagrangian approach of the Riemann solution procedure, which was originally proposed for perfect gases, to real gases, is nontrivial and requires the development of an exact real-gas Riemann solver for the Lagrangian form of the conservation laws. Calculations including complex wave interactions of various types were conducted to test the accuracy and robustness of the approach. Attention is given to the case of 2D oblique waves' capture, where a slip line is clearly in evidence; the real gas effect is demonstrated in the case of a generic engine nozzle.

  3. REACTIVE SPUTTER DEPOSITION OF CHROMIUM NITRIDE COATINGS

    EPA Science Inventory

    The effect of substrate temperature and sputtering gas compositon on the structure and properties of chromium-chromium nitride films deposited on C-1040 steel using r.f. magnetron sputter deposition was investigated. X-ray diffraction analysis was used to determine the structure ...

  4. Intercooler flow path for gas turbines: CFD design and experiments

    SciTech Connect

    Agrawal, A.K.; Gollahalli, S.R.; Carter, F.L.

    1995-10-01

    The Advanced Turbine Systems (ATS) program was created by the U.S. Department of Energy to develop ultra-high efficiency, environmentally superior, and cost competitive gas turbine systems for generating electricity. Intercooling or cooling of air between compressor stages is a feature under consideration in advanced cycles for the ATS. Intercooling entails cooling of air between the low pressure (LP) and high pressure (BP) compressor sections of the gas turbine. Lower air temperature entering the HP compressor decreases the air volume flow rate and hence, the compression work. Intercooling also lowers temperature at the HP discharge, thus allowing for more effective use of cooling air in the hot gas flow path. The thermodynamic analyses of gas turbine cycles with modifications such as intercooling, recuperating, and reheating have shown that intercooling is important to achieving high efficiency gas turbines. The gas turbine industry has considerable interest in adopting intercooling to advanced gas turbines of different capacities. This observation is reinforced by the US Navys Intercooled-Recuperative (ICR) gas turbine development program to power the surface ships. In an intercooler system, the air exiting the LP compressor must be decelerated to provide the necessary residence time in the heat exchanger. The cooler air must subsequently be accelerated towards the inlet of the HP compressor. The circumferential flow nonuniformities inevitably introduced by the heat exchanger, if not isolated, could lead to rotating stall in the compressors, and reduce the overall system performance and efficiency. Also, the pressure losses in the intercooler flow path adversely affect the system efficiency and hence, must be minimized. Thus, implementing intercooling requires fluid dynamically efficient flow path with minimum flow nonuniformities and consequent pressure losses.

  5. Cascading Tesla Oscillating Flow Diode for Stirling Engine Gas Bearings

    NASA Technical Reports Server (NTRS)

    Dyson, Rodger

    2012-01-01

    Replacing the mechanical check-valve in a Stirling engine with a micromachined, non-moving-part flow diode eliminates moving parts and reduces the risk of microparticle clogging. At very small scales, helium gas has sufficient mass momentum that it can act as a flow controller in a similar way as a transistor can redirect electrical signals with a smaller bias signal. The innovation here forces helium gas to flow in predominantly one direction by offering a clear, straight-path microchannel in one direction of flow, but then through a sophisticated geometry, the reversed flow is forced through a tortuous path. This redirection is achieved by using microfluid channel flow to force the much larger main flow into this tortuous path. While microdiodes have been developed in the past, this innovation cascades Tesla diodes to create a much higher pressure in the gas bearing supply plenum. In addition, the special shape of the leaves captures loose particles that would otherwise clog the microchannel of the gas bearing pads.

  6. A coupled model for solid deformation and gas leak flow

    NASA Astrophysics Data System (ADS)

    Sun, Peide; Wan, Huagen

    2004-09-01

    From the viewpoint of interaction mechanics of solid and gas, a coupled mathematical model is presented for solid coal/rock-mass deformation and gas leak flow in parallel deformable coal seams. Numerical solutions using the strong implicit procedure (SIP) method to the coupled mathematical model for double parallel coal seams are also developed in detail. Numerical simulations for the prediction of safety range using protection layer mining are performed with experimental data from a mine with potential danger of coal/gas outbursts. Analyses show that the numerical simulation results are consistent with the measured data on the spot. The coupled model shows a positive future for applications in a wide range of gas-leak-flow-related problems in mining engineering, gas drainage engineering and mining safety engineering. Copyright

  7. Gas-Liquid Flows and Phase Separation

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    2004-01-01

    Common issues for space system designers include:Ability to Verify Performance in Normal Gravity prior to Deployment; System Stability; Phase Accumulation & Shedding; Phase Separation; Flow Distribution through Tees & Manifolds Boiling Crisis; Heat Transfer Coefficient; and Pressure Drop.The report concludes:Guidance similar to "A design that operates in a single phase is less complex than a design that has two-phase flow" is not always true considering the amount of effort spent on pressurizing, subcooling and phase separators to ensure single phase operation. While there is still much to learn about two-phase flow in reduced gravity, we have a good start. Focus now needs to be directed more towards system level problems .

  8. Flow field thermal gradient gas chromatography.

    PubMed

    Boeker, Peter; Leppert, Jan

    2015-09-01

    Negative temperature gradients along the gas chromatographic separation column can maximize the separation capabilities for gas chromatography by peak focusing and also lead to lower elution temperatures. Unfortunately, so far a smooth thermal gradient over a several meters long separation column could only be realized by costly and complicated manual setups. Here we describe a simple, yet flexible method for the generation of negative thermal gradients using standard and easily exchangeable separation columns. The measurements made with a first prototype reveal promising new properties of the optimized separation process. The negative thermal gradient and the superposition of temperature programming result in a quasi-parallel separation of components each moving simultaneously near their lowered specific equilibrium temperatures through the column. Therefore, this gradient separation process is better suited for thermally labile molecules such as explosives and natural or aroma components. High-temperature GC methods also benefit from reduced elution temperatures. Even for short columns very high peak capacities can be obtained. In addition, the gradient separation is particularly beneficial for very fast separations below 1 min overall retention time. Very fast measurements of explosives prove the benefits of using negative thermal gradients. The new concept can greatly reduce the cycle time of high-resolution gas chromatography and can be integrated into hyphenated or comprehensive gas chromatography setups.

  9. Effect of nitrogen flow ratios on the structure and mechanical properties of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tsai, Du-Cheng; Huang, Yen-Lin; Lin, Sheng-Ru; Liang, Shih-Chang; Shieu, Fuh-Sheng

    2010-12-01

    This study reports the influence of growth conditions on the characteristics of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering at various N 2-to-total (N 2 + Ar) flow ratio, which is R N. The crystal structures, microstructure, and mechanical properties for different R N were characterized by electron spectroscopy for chemical analysis, X-ray diffraction, atomic force microscopy, field-emission-scanning electron microscopy, transmission electron microscopy, and nanoindentation. The results indicate that the TiVCrZrY alloy and nitride coatings have hexagonal close-packed (hcp)-type and sodium chloride (NaCl)-type solid-solution structures, respectively. The voids in the coatings are eliminated and the growth of the columnar crystal structures is inhibited along with an increasing R N. As a consequence, highly packed equiaxed amorphous structures with smooth surfaces are formed. The coatings accordingly achieved a pronounce hardness of 17.5 GPa when R N = 100%.

  10. Gas liquid flow at microgravity conditions - Flow patterns and their transitions

    NASA Technical Reports Server (NTRS)

    Dukler, A. E.; Fabre, J. A.; Mcquillen, J. B.; Vernon, R.

    1987-01-01

    The prediction of flow patterns during gas-liquid flow in conduits is central to the modern approach for modeling two phase flow and heat transfer. The mechanisms of transition are reasonably well understood for flow in pipes on earth where it has been shown that body forces largely control the behavior observed. This work explores the patterns which exist under conditions of microgravity when these body forces are suppressed. Data are presented which were obtained for air-water flow in tubes during drop tower experiments and Learjet trajectories. Preliminary models to explain the observed flow pattern map are evolved.

  11. Influence of the sputtering flow regime on the structural properties and magnetic behavior of Fe-Ga thin films (Ga ˜ 30 at.%)

    NASA Astrophysics Data System (ADS)

    Muñoz-Noval, A.; Ordóñez-Fontes, A.; Ranchal, R.

    2016-06-01

    In this paper we analyze the structure of Fe-Ga layers with a Ga content of ˜30 at.% deposited by the sputtering technique under two different regimes. We also studied the correlation between the structure and magnetic behavior of the samples. Keeping the Ar pressure fixed, we modified the flow regime from ballistic to diffusive by increasing the distance between the target and the substrate. X-ray diffraction measurements have shown a lower structural quality when growing in the diffusive flow. We investigated the impact of the growth regime by means of x-ray absorption fine structure (XAFS) measurements and obtained signs of its influence on the local atomic order. Full multiple scattering and finite difference calculations based on XAFS measurements point to a more relevant presence of a disordered A 2 phase and of orthorhombic Ga clusters on the Fe-Ga alloy deposited under a diffusive regime; however, in the ballistic sample, a higher presence of D 03/B 2 phases is evidenced. Structural characteristics, from local to long range, seem to determine the magnetic behavior of the layers. Whereas a clear in-plane magnetic anisotropy is observed in the film deposited under ballistic flow, the diffusive sample is magnetically isotropic. Therefore, our experimental results provide evidence of a correlation between flow regime and structural properties and its impact on the magnetic behavior of a rather unexplored compositional region of Fe-Ga compounds.

  12. Gas-Dynamic Transients Flow Networks

    1987-09-01

    TVENT1P predicts flows and pressures in a ventilation system or other air pathway caused by pressure transients, such as a tornado. For an analytical model to simulate an actual system, it must have (1) the same arrangement of components in a network of flow paths; (2) the same friction characteristics; (3) the same boundary pressures; (4) the same capacitance; and (5) the same forces that drive the air. A specific set of components used formore » constructing the analytical model includes filters, dampers, ducts, blowers, rooms, or volume connected at nodal points to form networks. The effects of a number of similar components can be lumped into a single one. TVENT1P contains a material transport algorithm and features for turning blowers off and on, changing blower speeds, changing the resistance of dampers and filters, and providing a filter model to handle very high flows. These features make it possible to depict a sequence of events during a single run. Component properties are varied using time functions. The filter model is not used by the code unless it is specified by the user. The basic results of a TVENT1P solution are flows in branches and pressures at nodes. A postprocessor program, PLTTEX, is included to produce the plots specified in the TVENT1P input. PLTTEX uses the proprietary CA-DISSPLA graphics software.« less

  13. Effects of substrate bias and nitrogen flow ratio on the surface morphology and binding state of reactively sputtered ZrN x films before and after annealing

    NASA Astrophysics Data System (ADS)

    Jeng, J. S.; Chen, J. S.

    2009-07-01

    ZrN x films were sputtered in an Ar + N 2 atmosphere, with different substrate biases (0 to -200 V) at various nitrogen flow ratios (%N 2 = 0.5-24%). The surface morphology, resistivity, crystllinity, and bonding configuration of ZrN x films, before and after vacuum annealing, were investigated. As compared with ZrN x films grown without substrate bias, before and after annealing, the resistivity of 1% and 2% N 2 films decreases with increasing substrate biases. Simultaneously, if the applied bias is too high, the crystallinity of ZrN x film will decrease. The surfaces of 1% and 2% N 2 flow films deposited without bias have small nodules, whereas the surface morphology of films deposited at -100 V of substrate bias exhibits large nodules and rugged surface. Once a -200 V of substrate bias is applied to the substrate, the surface morphology of ZrN x films, grown at 1% and 2% nitrogen flow ratios, is smooth. Furthermore, there are two deconvoluted peaks in XPS spectra (i.e., Zr-O and Zr-N) of ZrN x films deposited at -200 V of substrate bias before and after annealing. On the other hand, the surface morphology changes dramatically from rugged surfaces for film deposited at lower nitrogen flow ratio (%N 2 < 1%) to smoother and denser surfaces for film grown at higher nitrogen flow ratio (%N 2 ≥ 1%). The Zr-N bonding in 2% N 2 films still exist after annealing at 700 °C, while the Zr-N bonding in 0.5% and 16% N 2 flow film vanish at the same temperature. The connection between the resistivity, crystallinity, surface morphology, and bonding configuration of ZrN x films and how they are influenced by the substrate bias and nitrogen flow ratio are discussed in this paper.

  14. Conical flow near singular rays. [shock generation in ideal gas

    NASA Technical Reports Server (NTRS)

    Zahalak, G. I.; Myers, M. K.

    1974-01-01

    The steady flow of an ideal gas past a conical body is investigated by the method of matched asymptotic expansions, with particular emphasis on the flow near the singular ray occurring in linearized theory. The first-order problem governing the flow in this region is formulated, leading to the equation of Kuo, and an approximate solution is obtained in the case of compressive flow behind the main front. This solution is compared with the results of previous investigations with a view to assessing the applicability of the Lighthill-Whitham theories.

  15. About the statistical description of gas-liquid flows

    SciTech Connect

    Sanz, D.; Guido-Lavalle, G.; Carrica, P.

    1995-09-01

    Elements of the probabilistic geometry are used to derive the bubble coalescence term of the statistical description of gas liquid flows. It is shown that the Boltzmann`s hypothesis, that leads to the kinetic theory of dilute gases, is not appropriate for this kind of flows. The resulting integro-differential transport equation is numerically integrated to study the flow development in slender bubble columns. The solution remarkably predicts the transition from bubbly to slug flow pattern. Moreover, a bubbly bimodal size distribution is predicted, which has already been observed experimentally.

  16. Residence time distributions of gas flowing through rotating drum bioreactors.

    PubMed

    Hardin, M T; Howes, T; Mitchell, D A

    2001-07-20

    Residence time distribution studies of gas through a rotating drum bioreactor for solid-state fermentation were performed using carbon monoxide as a tracer gas. The exit concentration as a function of time differed considerably from profiles expected for plug flow, plug flow with axial dispersion, and continuous stirred tank reactor (CSTR) models. The data were then fitted by least-squares analysis to mathematical models describing a central plug flow region surrounded by either one dead region (a three-parameter model) or two dead regions (a five-parameter model). Model parameters were the dispersion coefficient in the central plug flow region, the volumes of the dead regions, and the exchange rates between the different regions. The superficial velocity of the gas through the reactor has a large effect on parameter values. Increased superficial velocity tends to decrease dead region volumes, interregion transfer rates, and axial dispersion. The significant deviation from CSTR, plug flow, and plug flow with axial dispersion of the residence time distribution of gas within small-scale reactors can lead to underestimation of the calculation of mass and heat transfer coefficients and hence has implications for reactor design and scale-up. PMID:11370003

  17. Axial flow positive displacement worm gas generator

    NASA Technical Reports Server (NTRS)

    Murrow, Kurt David (Inventor); Giffin, Rollin George (Inventor); Fakunle, Oladapo (Inventor)

    2010-01-01

    An axial flow positive displacement engine has an inlet axially spaced apart and upstream from an outlet. Inner and outer bodies have offset inner and outer axes extend from the inlet to the outlet through first, second, and third sections of a core assembly in serial downstream flow relationship. At least one of the bodies is rotatable about its axis. The inner and outer bodies have intermeshed inner and outer helical blades wound about the inner and outer axes respectively. The inner and outer helical blades extend radially outwardly and inwardly respectively. The helical blades have first, second, and third twist slopes in the first, second, and third sections respectively. The first twist slopes are less than the second twist slopes and the third twist slopes are less than the second twist slopes. A combustor section extends axially downstream through at least a portion of the second section.

  18. Turbine exhaust diffuser with region of reduced flow area and outer boundary gas flow

    DOEpatents

    Orosa, John

    2014-03-11

    An exhaust diffuser system and method for a turbine engine. The outer boundary may include a region in which the outer boundary extends radially inwardly toward the hub structure and may direct at least a portion of an exhaust flow in the diffuser toward the hub structure. At least one gas jet is provided including a jet exit located on the outer boundary. The jet exit may discharge a flow of gas downstream substantially parallel to an inner surface of the outer boundary to direct a portion of the exhaust flow in the diffuser toward the outer boundary to effect a radially outward flow of at least a portion of the exhaust gas flow toward the outer boundary to balance an aerodynamic load between the outer and inner boundaries.

  19. Do tropical wetland plants possess convective gas flow mechanisms?

    PubMed

    Konnerup, Dennis; Sorrell, Brian K; Brix, Hans

    2011-04-01

    • Internal pressurization and convective gas flow, which can aerate wetland plants more efficiently than diffusion, are common in temperate species. Here, we present the first survey of convective flow in a range of tropical plants. • The occurrence of pressurization and convective flow was determined in 20 common wetland plants from the Mekong Delta in Vietnam. The diel variation in pressurization in culms and the convective flow and gas composition from stubbles were examined for Eleocharis dulcis, Phragmites vallatoria and Hymenachne acutigluma, and related to light, humidity and air temperature. • Nine of the 20 species studied were able to build up a static pressure of > 50 Pa, and eight species had convective flow rates higher than 1 ml min(-1). There was a clear diel variation, with higher pressures and flows during the day than during the night, when pressures and flows were close to zero. • It is concluded that convective flow through shoots and rhizomes is a common mechanism for below-ground aeration of tropical wetland plants and that plants with convective flow might have a competitive advantage for growth in deep water.

  20. Do tropical wetland plants possess convective gas flow mechanisms?

    PubMed

    Konnerup, Dennis; Sorrell, Brian K; Brix, Hans

    2011-04-01

    • Internal pressurization and convective gas flow, which can aerate wetland plants more efficiently than diffusion, are common in temperate species. Here, we present the first survey of convective flow in a range of tropical plants. • The occurrence of pressurization and convective flow was determined in 20 common wetland plants from the Mekong Delta in Vietnam. The diel variation in pressurization in culms and the convective flow and gas composition from stubbles were examined for Eleocharis dulcis, Phragmites vallatoria and Hymenachne acutigluma, and related to light, humidity and air temperature. • Nine of the 20 species studied were able to build up a static pressure of > 50 Pa, and eight species had convective flow rates higher than 1 ml min(-1). There was a clear diel variation, with higher pressures and flows during the day than during the night, when pressures and flows were close to zero. • It is concluded that convective flow through shoots and rhizomes is a common mechanism for below-ground aeration of tropical wetland plants and that plants with convective flow might have a competitive advantage for growth in deep water. PMID:21175639

  1. Interaction of a surface glow discharge with a gas flow

    SciTech Connect

    Aleksandrov, A. L. Schweigert, I. V.

    2010-05-15

    A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250-300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow's influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.

  2. Hybrid continuum–molecular modelling of multiscale internal gas flows

    SciTech Connect

    Patronis, Alexander; Lockerby, Duncan A.; Borg, Matthew K.; Reese, Jason M.

    2013-12-15

    We develop and apply an efficient multiscale method for simulating a large class of low-speed internal rarefied gas flows. The method is an extension of the hybrid atomistic–continuum approach proposed by Borg et al. (2013) [28] for the simulation of micro/nano flows of high-aspect ratio. The major new extensions are: (1) incorporation of fluid compressibility; (2) implementation using the direct simulation Monte Carlo (DSMC) method for dilute rarefied gas flows, and (3) application to a broader range of geometries, including periodic, non-periodic, pressure-driven, gravity-driven and shear-driven internal flows. The multiscale method is applied to micro-scale gas flows through a periodic converging–diverging channel (driven by an external acceleration) and a non-periodic channel with a bend (driven by a pressure difference), as well as the flow between two eccentric cylinders (with the inner rotating relative to the outer). In all these cases there exists a wide variation of Knudsen number within the geometries, as well as substantial compressibility despite the Mach number being very low. For validation purposes, our multiscale simulation results are compared to those obtained from full-scale DSMC simulations: very close agreement is obtained in all cases for all flow variables considered. Our multiscale simulation is an order of magnitude more computationally efficient than the full-scale DSMC for the first and second test cases, and two orders of magnitude more efficient for the third case.

  3. Influence of Gas Flow Rate for Formation of Aligned Nanorods in ZnO Thin Films for Solar-Driven Hydrogen Production

    SciTech Connect

    Shet, S.; Chen, L.; Tang, H.; Nuggehalli, R.; Wang, H.; Yan, Y.; Turner, J.; Al-Jassim, M.

    2012-04-01

    ZnO thin films have been deposited in mixed Ar/N{sub 2} gas ambient at substrate temperature of 500 C by radiofrequency sputtering of ZnO targets. We find that an optimum N{sub 2}-to-Ar ratio in the deposition ambient promotes the formation of well-aligned nanorods. ZnO thin films grown in ambient with 25% N{sub 2} gas flow rate promoted nanorods aligned along c-axis and exhibit significantly enhanced photoelectrochemical (PEC) response, compared with ZnO thin films grown in an ambient with different N{sub 2}-to-Ar gas flow ratios. Our results suggest that chamber ambient is critical for the formation of aligned nanostructures, which offer potential advantages for improving the efficiency of PEC water splitting for H{sub 2} production.

  4. Lattice Boltzmann equation for microscale gas flows of binary mixtures.

    PubMed

    Guo, Zhaoli; Asinari, Pietro; Zheng, Chuguang

    2009-02-01

    Modeling and simulating gas flows in and around microdevices are a challenging task in both science and engineering. In practical applications, a gas is usually a mixture made of different components. In this paper we propose a lattice Boltzmann equation (LBE) model for microscale flows of a binary mixture based on a recently developed LBE model for continuum mixtures [P. Asinari and L.-S. Luo, J. Comput. Phys. 227, 3878 (2008)]. A consistent boundary condition for gas-solid interactions is proposed and analyzed. The LBE is validated and compared with theoretical results or other reported data. The results show that the model can serve as a potential method for flows of binary mixture in the microscale.

  5. Gas, liquids flow rates hefty at Galveston Bay discovery

    SciTech Connect

    Petzet, G.A.

    1998-01-19

    Extended flow tests indicate a large Vicksburg (Oligocene) gas, condensate, and oil field is about to be developed in western Galveston Bay. Internal estimates indicates that ultimate recovery from the fault block in which the discovery well was drilled could exceed 1 tcf of gas equivalent of proved, possible, and probable reserves. The paper discusses the test program for this field and other prospects in the Galveston Bay area.

  6. Flow reversing in the gas layer in droplet impact

    NASA Astrophysics Data System (ADS)

    Jian, Zhen; Ray, Pascal; Josserand, Christophe; Zaleski, Stephane

    2015-03-01

    Recent numerical and experimental studies demonstrated the crucial role of surrounding gas in droplet impact. Whereas, the mechanism of gas effect in droplet splashing is still far from a crystal clear comprehension. Complicated dynamics occur in a small temporal and spatial scale before direct contact with the target surface, which are related to the origin of the splashing. Direct numerical simulations were executed with a code called Gerris for both droplet impact on a liquid surface and on a solid subtract. New dynamics in the gas layer between the droplet and the target surface were discovered. Unexpectedly, a``reversing'' gas flow (towards the center) is observed as the droplet approaches the target surface. With further descending of the droplet, the flow is reversed and evacuates towards the outside. The reversing of the flow motion direction is followed by the pressure jump and the dimple formation which have been reported as some crucial gas dynamics in droplet splashing mechanism in our previous work. An aerodynamic mechanism is proposed for the flow reversing dynamics.

  7. Effects of oxygen gas pressure on structural, electrical, and thermoelectric properties of (ZnO){sub 3}In{sub 2}O{sub 3} thin films deposited by rf magnetron sputtering

    SciTech Connect

    Orikasa, Yuki; Hayashi, Naoaki; Muranaka, Shigetoshi

    2008-06-01

    Zinc indium oxide films were deposited by the rf magnetron sputtering method using a (ZnO){sub 3}In{sub 2}O{sub 3} target. The films were prepared at 573 K in various Ar/O{sub 2} sputtering gases (O{sub 2} content: 0%-25%). The effect of the oxygen gas content in the sputtering gas on the structural, optical, electrical, and thermoelectric properties of the films was investigated. The films had a c-axis oriented layer structure. The films deposited at 0%-3% oxygen gas contents exhibited a high electrical conductivity with a high carrier concentration, n{approx_equal}10{sup 20} cm{sup -3}, while the conductivity of the films significantly decreased above the 3% oxygen gas content, having a carrier concentration below 10{sup 18} cm{sup -3}. From the optical transmission measurement, the band gap of the films was estimated to be 3.01 eV. The films deposited at 3%-8% oxygen gas contents showed a high Seebeck coefficient, -300 {mu}V/K, while the maximum power factor, 4.78x10{sup -5} W/m K{sup 2}, was obtained at the 2% oxygen gas content. The Seebeck coefficient and the power factor were calculated on the basis of degenerate semiconductors. These results suggest that zinc indium oxide films have the possibility of being high performance thermoelectric materials.

  8. Statistical Simulation of Gas Flows through Short Rough Microchannels

    NASA Astrophysics Data System (ADS)

    Markelov, G.; Stefanov, S.

    2011-11-01

    Rarefied gas flow though the rough microchannel is modeled using the direct simulation Monte Carlo method (DSMC). Deterministic and statistical methods of wall roughness deception have been applied. The well-known DSMC-based software, SMILE, allows one to model a flow through the channel with an arbitrary shape, here series of triangular obstacles has been modeled. A statistical approach is based on porous layer model of dusty gas and the model has been implemented in SMILE. Results obtained with two methods are compared and channel performance is presented for different pressure ratio and size of obstacles.

  9. Prediction of strongly-heated internal gas flows

    SciTech Connect

    McEligot, D.M. ||; Shehata, A.M.; Kunugi, Tomoaki |

    1997-12-31

    The purposes of the present article are to remind practitioners why the usual textbook approaches may not be appropriate for treating gas flows heated from the surface with large heat fluxes and to review the successes of some recent applications of turbulence models to this case. Simulations from various turbulence models have been assessed by comparison to the measurements of internal mean velocity and temperature distributions by Shehata for turbulent, laminarizing and intermediate flows with significant gas property variation. Of about fifteen models considered, five were judged to provide adequate predictions.

  10. Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

    NASA Technical Reports Server (NTRS)

    Mielke, Amy F.; Elam, Kristie A.; Sung, Chih-Jen

    2008-01-01

    A molecular Rayleigh scattering technique is developed to measure time-resolved gas velocity, temperature, and density in unseeded gas flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultipler tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. Mean and rms velocity and temperature fluctuation measurements in both an electrically-heated jet facility with a 10-mm diameter nozzle and also in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA Glenn Research Center are presented.

  11. Structural support bracket for gas flow path

    DOEpatents

    None

    2016-08-02

    A structural support system is provided in a can annular gas turbine engine having an arrangement including a plurality of integrated exit pieces (IEPs) forming an annular chamber for delivering gases from a plurality of combustors to a first row of turbine blades. A bracket structure is connected between an IEP and an inner support structure on the engine. The bracket structure includes an axial bracket member attached to an IEP and extending axially in a forward direction. A transverse bracket member has an end attached to the inner support structure and extends circumferentially to a connection with a forward end of the axial bracket member. The transverse bracket member provides a fixed radial position for the forward end of the axial bracket member and is flexible in the axial direction to permit axial movement of the axial bracket member.

  12. Influence of flowing helium gas on plasma plume formation in atmospheric pressure plasma

    SciTech Connect

    Yambe, Kiyoyuki; Konda, Kohmei; Ogura, Kazuo

    2015-05-15

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and a foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. The helium gas flowing out of quartz tube mixes with air, and the flow channel is composed of the regions of flowing helium gas and air. The plasma plume length is equivalent to the reachable distance of flowing helium gas. Although the amount of helium gas on the flow channel increases by increasing the inner diameter of quartz tube at the same gas flow velocity, the plasma plume length peaks at around 8 m/s of gas flow velocity, which is the result that a flow of helium gas is balanced with the amount of gas. The plasma plume is formed at the boundary region where the flow of helium gas is kept to the wall of the air.

  13. Interaction of a surface glow discharge with a gas flow

    NASA Astrophysics Data System (ADS)

    Aleksandrov, A. L.; Schweigert, I. V.

    2010-05-01

    A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250-300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow’s influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.

  14. Laser absorption phenomena in flowing gas devices

    NASA Technical Reports Server (NTRS)

    Chapman, P. K.; Otis, J. H.

    1976-01-01

    A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster.

  15. Nonideal isentropic gas flow through converging-diverging nozzles

    NASA Technical Reports Server (NTRS)

    Bober, W.; Chow, W. L.

    1990-01-01

    A method for treating nonideal gas flows through converging-diverging nozzles is described. The method incorporates the Redlich-Kwong equation of state. The Runge-Kutta method is used to obtain a solution. Numerical results were obtained for methane gas. Typical plots of pressure, temperature, and area ratios as functions of Mach number are given. From the plots, it can be seen that there exists a range of reservoir conditions that require the gas to be treated as nonideal if an accurate solution is to be obtained.

  16. Flow mechanism of Forchheimer's cubic equation in high-velocity radial gas flow through porous media

    SciTech Connect

    Ezeudembah, A.S.; Dranchuk, P.M.

    1982-01-01

    Formal derivation of Forchheimer's cubic equation is made by considering the kinetic energy equation of mean flow and dimensional relations for one-dimensional, linear, incompressible fluid flow. By the addition of the cubic term, this equation is regarded as a modified Forchheimer's quadratic equation which accounts for the flow rates obtained beyond the laminar flow condition. The cubic equation spans a wide range of flow rates and regimes. For suitable use in gas flow studies, this equation has been adapted, modified, and corrected for the gas slippage effect. The physical basis of the cubic term has been established by using boundary layer theory to explain the high-velocity, high-pressure flow behavior through a porous path. Gamma, the main parameter in the cubic term, is related directly to a characteristic, dimensionless shape factor which is significant at higher flow rates. It is inversely related to viscosity, but has no dependence on the gas slippage coefficient in the higher flow regime. 25 references.

  17. Sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

  18. Wet gas flow modeling for a vertically mounted Venturi meter

    NASA Astrophysics Data System (ADS)

    Xu, Lijun; Zhou, Wanlu; Li, Xiaomin

    2012-04-01

    Venturi meters are playing an increasingly important role in wet gas metering in natural gas and oil industries. Due to the effect of liquid in a wet gas, the differential pressure over the converging section of a Venturi meter is higher than that when a pure gas flows through with the same flow rate. This phenomenon is referred to as over-reading. Thus, a correction for the over-reading is required. Most of the existing wet gas models are more suitable for higher pressure (>2 MPa) than lower pressure (<1 MPa). Much attention has been paid on higher quality (>0.5) than lower quality (<0.5) in recent years. However, conditions of lower pressure and lower quality also widely exist in the gas and oil industries. By comparing the performances of eight existing wet gas models in low-pressure range of 0.26-0.86 MPa and low-quality range of 0.07-0.36 with a vertically mounted Venturi meter of diameter ratio 0.45, de Leeuw's model was proven to perform best. Derived from de Leeuw's model, a modified model with better performance for the low-pressure and low-quality ranges was obtained. Experimental data showed that the root mean square of the relative errors of the over-reading was 2.30%.

  19. Formation of cubic boron-nitride by the reactive sputter deposition of boron

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; Makowiecki, D.W.; McKeman, M.A.

    1997-03-01

    Boron-nitride films are synthesized by RF magnetron sputtering boron targets where the deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are analyzed using Auger electron spectroscopy, transmission electron microscopy, nanoindentation, Raman spectroscopy and x-ray absorption spectroscopy. These techniques provide characterization of film composition, crystalline structure, hardness and chemical bonding, respectively. Reactive, rf-sputtering process parameters are established which lead to the growth of crystalline BN phases. The deposition of stable and adherent boron nitride coatings consisting of the cubic phase requires 400 `C substrate heating and the application of a 300 V negative bias.

  20. Review of coaxial flow gas core nuclear rocket fluid mechanics

    NASA Technical Reports Server (NTRS)

    Weinstein, H.

    1976-01-01

    Almost all of the fluid mechanics research associated with the coaxial flow gas core reactor ended abruptly with the interruption of NASA's space nuclear program because of policy and budgetary considerations in 1973. An overview of program accomplishments is presented through a review of the experiments conducted and the analyses performed. Areas are indicated where additional research is required for a fuller understanding of cavity flow and of the factors which influence cold and hot flow containment. A bibliography is included with graphic material.

  1. A Two-Dimensional Compressible Gas Flow Code

    1995-03-17

    F2D is a general purpose, two dimensional, fully compressible thermal-fluids code that models most of the phenomena found in situations of coupled fluid flow and heat transfer. The code solves momentum, continuity, gas-energy, and structure-energy equations using a predictor-correction solution algorithm. The corrector step includes a Poisson pressure equation. The finite difference form of the equation is presented along with a description of input and output. Several example problems are included that demonstrate the applicabilitymore » of the code in problems ranging from free fluid flow, shock tubes and flow in heated porous media.« less

  2. Large-Flow-Area Flow-Selective Liquid/Gas Separator

    NASA Technical Reports Server (NTRS)

    Vasquez, Arturo; Bradley, Karla F.

    2010-01-01

    This liquid/gas separator provides the basis for a first stage of a fuel cell product water/oxygen gas phase separator. It can separate liquid and gas in bulk in multiple gravity environments. The system separates fuel cell product water entrained with circulating oxygen gas from the outlet of a fuel cell stack before allowing the gas to return to the fuel cell stack inlet. Additional makeup oxygen gas is added either before or after the separator to account for the gas consumed in the fuel cell power plant. A large volume is provided upstream of porous material in the separator to allow for the collection of water that does not exit the separator with the outgoing oxygen gas. The water then can be removed as it continues to collect, so that the accumulation of water does not impede the separating action of the device. The system is designed with a series of tubes of the porous material configured into a shell-and-tube heat exchanger configuration. The two-phase fluid stream to be separated enters the shell-side portion of the device. Gas flows to the center passages of the tubes through the porous material and is then routed to a common volume at the end of the tubes by simple pressure difference from a pumping device. Gas flows through the porous material of the tubes with greater ease as a function of the ratio of the dynamic viscosity of the water and gas. By careful selection of the dimensions of the tubes (wall thickness, porosity, diameter, length of the tubes, number of the tubes, and tube-to-tube spacing in the shell volume) a suitable design can be made to match the magnitude of water and gas flow, developed pressures from the oxygen reactant pumping device, and required residual water inventory for the shellside volume.

  3. Empirical slip and viscosity model performance for microscale gas flows.

    SciTech Connect

    Gallis, Michail A.; Boyd, Iain D.; McNenly, Matthew J.

    2004-07-01

    For the simple geometries of Couette and Poiseuille flows, the velocity profile maintains a similar shape from continuum to free molecular flow. Therefore, modifications to the fluid viscosity and slip boundary conditions can improve the continuum based Navier-Stokes solution in the non-continuum non-equilibrium regime. In this investigation, the optimal modifications are found by a linear least-squares fit of the Navier-Stokes solution to the non-equilibrium solution obtained using the direct simulation Monte Carlo (DSMC) method. Models are then constructed for the Knudsen number dependence of the viscosity correction and the slip model from a database of DSMC solutions for Couette and Poiseuille flows of argon and nitrogen gas, with Knudsen numbers ranging from 0.01 to 10. Finally, the accuracy of the models is measured for non-equilibrium cases both in and outside the DSMC database. Flows outside the database include: combined Couette and Poiseuille flow, partial wall accommodation, helium gas, and non-zero convective acceleration. The models reproduce the velocity profiles in the DSMC database within an L{sub 2} error norm of 3% for Couette flows and 7% for Poiseuille flows. However, the errors in the model predictions outside the database are up to five times larger.

  4. Temporal interfacial instability in vertical gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Schmidt, Patrick; Ó Náraigh, Lennon; Lucquiaud, Mathieu; Valluri, Prashant

    2015-11-01

    We consider onset and dynamics of interfacial instability in gas-liquid flows, using two-dimensional channel flow of a thin falling film sheared by counter-current gas as a model. Our methodology consists of linear stability theory together with DNS of the two-phase flow in the case of nonlinear disturbances. We study the influence of three main flow parameters (density contrast between liquid and gas, film thickness, pressure drop applied to drive the gas stream) on the interfacial dynamics. Energy budget analyses based on Orr-Sommerfeld theory reveal coexisting unstable modes (interfacial, shear, internal) in the case of high density contrast, resulting in mode coalescence and mode competition, but only one dynamically relevant unstable interfacial mode for low density contrast. DNS of this scenario shows that linear theory holds up remarkably well upon the onset of large-amplitude waves as well as the existence of weakly nonlinear waves. In comparison, although linear stability theory successfully determines the most-dominant features in the interfacial wave dynamics at early-to-intermediate times in a high-density-contrast case, short waves selected by linear theory undergo secondary instability and the wave train is no longer regular but rather exhibits chaotic.

  5. Pockels-effect cell for gas-flow simulation

    NASA Technical Reports Server (NTRS)

    Weimer, D.

    1982-01-01

    A Pockels effect cell using a 75 cu cm DK*P crystal was developed and used as a gas flow simulator. Index of refraction gradients were produced in the cell by the fringing fields of parallel plate electrodes. Calibration curves for the device were obtained for index of refraction gradients in excess of .00025 m.

  6. Back-Pressure Regulator for Large Gas Flows

    NASA Technical Reports Server (NTRS)

    Theodore, E. A.; Chin, F.

    1985-01-01

    Cost reduced, and safety enhanced. Pipe exit partially obstructed by conical throat plug. When pressure in pipe falls below (or rises above) desired back pressure, plug automatically moved in (or out). Applications of system lie in environmental testing or production facilities requiring large gas flows at low pressures.

  7. Effects of argon gas flow rate on laser-welding.

    PubMed

    Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

    2012-01-01

    The purpose of this study was to evaluate the effects of the rate of argon gas flow on joint strength in the laser-welding of cast metal plates and to measure the porosity. Two cast plates (Ti and Co-Cr alloy) of the same metal were abutted and welded together. The rates of argon gas flow were 0, 5 and 10 L/min for the Co-Cr alloy, and 5 and 10 L/min for the Ti. There was a significant difference in the ratio of porosity according to the rate of argon gas flow in the welded area. Argon shielding had no significant effect on the tensile strength of Co-Cr alloy. The 5 L/min specimens showed greater tensile strength than the 10 L/min specimens for Ti. Laser welding of the Co-Cr alloy was influenced very little by argon shielding. When the rate of argon gas flow was high, joint strength decreased for Ti.

  8. Magnetron sputtering source

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.; Grabner, R.F.; Ramsey, P.B.

    1994-08-02

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal. 12 figs.

  9. Magnetron sputtering source

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.; Grabner, R. Fred; Ramsey, Philip B.

    1994-01-01

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal.

  10. Isothermal gas-liquid flow at reduced gravity

    NASA Technical Reports Server (NTRS)

    Dukler, A. E.

    1990-01-01

    Research on adiabatic gas-liquid flows under reduced gravity condition is presented together with experimental data obtained using a NASA-Lewis RC 100-ft drop tower and in a LeRC Learjet. It is found that flow patterns and characteristics remain unchanged after the first 1.5 s into microgravity conditions and that the calculated time for a continuity wave to traverse the test section is less than 1.2 s. It is also found that the dispersed bubbles move at the same velocity as that of the front of the slug and that the transition between bubbly and slug flow is insensitive to diameter. Both the bubbly and the slug flows are suggested to represent a continuum of the same physical process. The characteristics of annular, slug, and bubbly flows are compared.

  11. Coordinated scheduling of electricity and natural gas infrastructures with a transient model for natural gas flow.

    PubMed

    Liu, Cong; Shahidehpour, Mohammad; Wang, Jianhui

    2011-06-01

    This paper focuses on transient characteristics of natural gas flow in the coordinated scheduling of security-constrained electricity and natural gas infrastructures. The paper takes into account the slow transient process in the natural gas transmission systems. Considering their transient characteristics, natural gas transmission systems are modeled as a set of partial differential equations (PDEs) and algebraic equations. An implicit finite difference method is applied to approximate PDEs by difference equations. The coordinated scheduling of electricity and natural gas systems is described as a bi-level programming formulation from the independent system operator's viewpoint. The objective of the upper-level problem is to minimize the operating cost of electric power systems while the natural gas scheduling optimization problem is nested within the lower-level problem. Numerical examples are presented to verify the effectiveness of the proposed solution and to compare the solutions for steady-state and transient models of natural gas transmission systems.

  12. Optical density and velocity measurements in cryogenic gas flows

    NASA Astrophysics Data System (ADS)

    Jensen, O. S.; Kunsch, J. P.; Rösgen, T.

    2005-07-01

    This paper presents the application of optical measurement techniques in dense-gas flows in a heavy-gas channel to determine planar two-component (2C) velocity profiles and two-dimensional (2D) temperature profiles. The experimental approach is rather new in this area, and represents progress compared with the traditional techniques based on thermocouple measurements. The dense-gas flows are generated by the evaporation of liquid nitrogen. The optical measurement of both the velocity and density profiles is accomplished by the implementation of particle image velocimetry (PIV) and background-oriented schlieren (BOS) systems. Supplemental thermocouple measurements are used as independent calibrations to derive temperatures from the density data measured with the BOS system. The results obtained with both systems are used to quantify the dilution behavior of the propagating cloud through a global entrainment parameter β. Its value agrees well with the results obtained by earlier studies.

  13. In Situ Control of Gas Flow by Modification of Gas-Solid Interactions

    NASA Astrophysics Data System (ADS)

    Seo, Dongjin; Ducker, William A.

    2013-10-01

    The boundary condition for gas flow at the solid-gas interface can be altered by in situ control of the state of a thin film adsorbed to the solid. A monolayer of ocatadecyltrichlorosilane (OTS) reversibly undergoes a meltinglike transition. When the temperature of an OTS-coated particle and plate is moved through the range of OTS “melting” temperatures, there is a change in the lubrication force between the particle and plate in 1 atm of nitrogen gas. This change is interpreted in terms of a change in the flow of gas mediated by the slip length and tangential momentum accommodation coefficient (TMAC). There is a minimum in slip length (290 nm) at 18°C, which corresponds to a maximum in TMAC (0.44). The slip length increases to 590 nm at 40°C which corresponds to a TMAC of 0.25. We attribute the decrease in TMAC with increasing temperature to a decrease in roughness of the monolayer on melting, which allows a higher fraction of specular gas reflections, thereby conserving tangential gas momentum. The importance of this work is that it demonstrates the ability to control gas flow simply by altering the interface for fixed geometry and gas properties.

  14. Analytical and Numerical Modeling of Strongly Rotating Rarefied Gas Flows

    NASA Astrophysics Data System (ADS)

    Pradhan, Sahadev; Kumaran, Viswanathan

    2015-11-01

    Centrifugal gas separation processes effect separation by utilizing the difference in the mole fraction in a high speed rotating cylinder caused by the difference in molecular mass, and consequently the centrifugal force density. These have been widely used in isotope separation because chemical separation methods cannot be used to separate isotopes of the same chemical species. More recently, centrifugal separation has also been explored for the separation of gases such as carbon dioxide and methane. The efficiency of separation is critically dependent on the secondary flow generated due to temperature gradients at the cylinder wall or due to inserts, and it is important to formulate accurate models for this secondary flow. The widely used Onsager model for secondary flow is restricted to very long cylinders where the length is large compared to the diameter, the limit of high stratification parameter, where the gas is restricted to a thin layer near the wall of the cylinder, and it assumes that there is no mass difference in the two species while calculating the secondary flow. There are two objectives of the present analysis of the rarefied gas flow in a rotating cylinder. The first is to remove the restriction of high stratification parameter, and to generalize the solutions to low rotation speeds where the stratification parameter may be O(1), and to apply for dissimilar gases considering the difference in molecular mass of the two species. Secondly, we would like to compare the predictions with molecular simulations based on the direct simulation Monte Carlo (DSMC) method for rarefied gas flows, in order to quantify the errors resulting from the approximations at different aspect ratios, Reynolds number and stratification parameter.

  15. Effect of substrate temperature and gas flow ratio on the nanocomposite TiAlBN coating

    NASA Astrophysics Data System (ADS)

    Rosli, Z. M.; Kwan, W. L.; Juoi, J. M.

    2016-07-01

    Nanocomposite TiAlBN (nc-TiAlBN) coatings were successfully deposited via RF magnetron sputtering by varying the nitrogen-to-total gas flow ratio (RN), and substrate temperature (TS). All coatings were deposited on AISI 316 substrates using single Ti-Al-BN hot-pressed disc as a target. The grain size, phases, and chemical composition of the coatings were evaluated using glancing angle X-ray diffraction analysis (GAXRD) and X-ray photoelectron spectroscopy (XPS). Results showed that the grains size of the deposited nc-TiAlBN coatings were in the range of 3.5 to 5.7 nm and reached a nitride saturation state as early as 15 % RN. As the nitrogen concentration decreases, boron concentration increased from 9 at.% to 16.17 at.%. and thus, increase the TiB2 phase within the coatings. The TS, however, showed no significant effect either on the crystallographic structure, grain size, or in the chemical composition of the deposited nc-TiAlBN coating.

  16. Glow discharge in a fast longitudinal gas flow

    NASA Astrophysics Data System (ADS)

    Pashchenko, N. T.; Raizer, Iu. P.

    1982-09-01

    A one-dimensional formulation is used to analyze the entrainment of charges by the flow in a glow discharge in a longitudinal gas flow directed from the cathode to the anode. It is sought to determine whether a discharge can occur if, in contrast to the normal course of events, positive ions are carried by a fast flow toward the positive electrode. The results reveal that a flow, even if very fast, has relatively little effect on the discharge parameters. The discharge, however, acquires a structural feature similar to that which arises at supersonic gas flows. Here, the ion drift serves as the sound. Nothing that occurs outside the cathode sheath during the 'supersonic flow' has any effect on the events at the cathode. The anode sheath is observed to disappear. It is pointed out that this effect may improve the stability of the discharge with respect to instabilities nucleated near the anode and in the positive column, since the cathode 'senses' nothing and no change can occur in the processes occurring at the cathode.

  17. Solids flow mapping in gas-solid risers

    NASA Astrophysics Data System (ADS)

    Bhusarapu, Satish Babu

    Gas-solid risers are extensively used in many industrial processes for gas-solid reactions (e.g. coal combustion and gasification) and for solid catalyzed gas phase reactions (e.g. fluid catalytic cracking, butane oxidation to maleic anhydride). Ab initio prediction of the complex multiphase fluid dynamics in risers is not yet possible, which makes reactor modeling difficult. In particular, quantification of solids flow and mixing is important. Almost all the experimental techniques used to characterize solids flow lead to appreciable errors in measured variables in large scale, high mass flux systems. In addition, none of the experimental techniques provide all the relevant data required to develop a satisfactory solids flow model. In this study, non-invasive Computer Automated Radioactive Particle Tracking (CARPT) is employed to visualize and quantify the solids dynamics and mixing in the gas-solid riser of a Circulating Fluidized Bed (CFB). A single radioactive tracer particle is monitored during its multiple visits to the riser and with an assumption of ergodicity, the following flow parameters are estimated: (a) Overall solids mass flux in the CFB loop. (b) Solids residence time distribution in the riser and down-comer. (c) Lagrangian and Eulerian solids velocity fields in a fully-developed section of the riser. This includes velocity fluctuations and components of the diffusivity tensor. The existing CARPT technique is extended to large scale systems. A new algorithm, based on a cross-correlation search, is developed for position rendition from CARPT data. Two dimensional solids holdup profiles are estimated using gamma-ray computed tomography. The image quality from the tomography data is improved by implementing an alternating minimization algorithm. This work establishes for the first time a reliable database for local solids dynamic quantities such as time-averaged velocities, Reynolds stresses, eddy diffusivities and turbulent kinetic energy. In addition

  18. Going with the flow: using gas clouds to probe the accretion flow feeding Sgr A*

    NASA Astrophysics Data System (ADS)

    McCourt, Michael; Madigan, Ann-Marie

    2016-01-01

    The massive black hole in our Galactic centre, Sgr A*, accretes only a small fraction of the gas available at its Bondi radius. The physical processes determining this accretion rate remain unknown, partly due to a lack of observational constraints on the gas at distances between ˜10 and ˜105 Schwarzschild radii (Rs) from the black hole. Recent infrared observations identify low-mass gas clouds, G1 and G2, moving on highly eccentric, nearly co-planar orbits through the accretion flow around Sgr A*. Although it is not yet clear whether these objects contain embedded stars, their extended gaseous envelopes evolve independently as gas clouds. In this paper we attempt to use these gas clouds to constrain the properties of the accretion flow at ˜103 Rs. Assuming that G1 and G2 follow the same trajectory, we model the small differences in their orbital parameters as evolution resulting from interaction with the background flow. We find evolution consistent with the G-clouds originating in the clockwise disc. Our analysis enables the first unique determination of the rotation axis of the accretion flow: we localize the rotation axis to within 20°, finding an orientation consistent with the parsec-scale jet identified in X-ray observations and with the circumnuclear disc, a massive torus of molecular gas ˜1.5 pc from Sgr A*. This suggests that the gas in the accretion flow comes predominantly from the circumnuclear disc, rather than the winds of stars in the young clockwise disc. This result will be tested by the Event-Horizon Telescope within the next year. Our model also makes testable predictions for the orbital evolution of G1 and G2, falsifiable on a 5-10 year time-scale.

  19. Waves and instabilities in inclined gas-liquid pipe flow

    SciTech Connect

    Grolman, E.; Fortuin, J.M.H.

    1996-12-31

    The Modified Apparent Rough Surface (MARS) model successfully predicts liquid holdup and pressure gradient for wavy gas-liquid pipe flow in slightly inclined pipes, up to the transition to slug (intermittent) flow. Additional equations are used to predict the transition from wavy-to-intermittent flow and for the velocity of waves on the gas-liquid interface. In this paper, Linear (stability) Theory is compared with the MARS model, on the basis of measurements in horizontal and slightly inclined (0{degree} {le} {beta} 6{degree}) pipes. Viscous terms in the linear analysis require estimates of shear stresses. Using the MARS model for the interfacial and liquid-to-wall friction factors, stability can be predicted to within reasonable degree of accuracy. Credible wave velocities are also obtained, provided the interfacial waves are not assumed to be marginally stable. Earlier semi-theoretical equations (MARS model) still provide better estimates of both stability and wave velocity and are much easier to handle than Linear Theory. However, the use of good friction factor equations, i.e. those capable of predicting liquid holdup and pressure gradient, has significantly improved the results obtained with Linear Theory. This opens the way to further studies into the mechanisms determining the velocity, growth and instability of waves in gas-liquid pipe flow.

  20. Heat transfer and flow characteristics on a gas turbine shroud.

    PubMed

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions.

  1. Heat transfer and flow characteristics on a gas turbine shroud.

    PubMed

    Obata, M; Kumada, M; Ijichi, N

    2001-05-01

    The work described in this paper is an experimental investigation of the heat transfer from the main flow to a turbine shroud surface, which may be applicable to ceramic gas turbines. Three kinds of turbine shrouds are considered with a flat surface, a taper surface and a spiral groove surface opposite to the blades in an axial flow turbine of actual turbo-charger. Heat transfer measurements were performed for the experimental conditions of a uniform heat flux or a uniform wall temperature. The effects of the inlet flow angle, rotational speed, and tip clearance on the heat transfer coefficient were clarified under on- and off-design flow conditions. The mean heat transfer coefficient was correlated to the blade Reynolds number and tip clearance, and compared with an experimental correlation and measurements of a flat surface. A comparison was also made for the measurement of static pressure distributions. PMID:11460639

  2. Fine-tuning control on CNT diameter distribution, length and density using thermal CVD growth at atmospheric pressure: an in-depth analysis on the role of flow rate and flow duration of acetylene (C2H2) gas

    NASA Astrophysics Data System (ADS)

    Tripathi, Nishant; Mishra, Prabhash; Harsh, Harsh; Islam, S. S.

    2015-01-01

    An optimization control has been demonstrated to obtain carbon nanotubes having specific diameter distribution, length, homogeneity, and yield during its growth by thermal chemical vapor deposition technique under atmospheric pressure. Carbon nanotubes (CNTs) were grown on silicon wafer where a predeposition of iron catalyst of 2 nm thickness was made by sputtering. The growth was conducted under two variable parameters, i.e., flow rate and flow duration. Argon and hydrogen mixture was used for pretreatment of catalyst and as etching gas, and acetylene as a carbon precursor. In-depth analysis shows that increase in flow rate from 10 to 50 sccm resulted in increase in the concentration of amorphous carbon, CNTs diameter range and decrease in length, we found best result at 20 sccm flow rate of acetylene gas. On the other hand, as we varied flow duration from 6 to 14 min, with keeping flow rate of acetylene 20 sccm constant, dense homogeneous growth of horizontal CNTs network plus an increase in length and diameter range were observed. An optimization of flow rate and flow duration is presented here to obtain a selective diameter distribution and length as expected by this growth technique. Atomic force microscopy, field emission scanning electron microscopy and Raman spectroscopy were used to investigate the samples' morphologies in support of the observations made.

  3. Data set from gas sensor array under flow modulation.

    PubMed

    Ziyatdinov, Andrey; Fonollosa, Jordi; Fernández, Luis; Gutiérrez-Gálvez, Agustín; Marco, Santiago; Perera, Alexandre

    2015-06-01

    Recent studies in neuroscience suggest that sniffing, namely sampling odors actively, plays an important role in olfactory system, especially in certain scenarios such as novel odorant detection. While the computational advantages of high frequency sampling have not been yet elucidated, here, in order to motivate further investigation in active sampling strategies, we share the data from an artificial olfactory system made of 16 MOX gas sensors under gas flow modulation. The data were acquired on a custom set up featured by an external mechanical ventilator that emulates the biological respiration cycle. 58 samples were recorded in response to a relatively broad set of 12 gas classes, defined from different binary mixtures of acetone and ethanol in air. The acquired time series show two dominant frequency bands: the low-frequency signal corresponds to a conventional response curve of a sensor in response to a gas pulse, and the high-frequency signal has a clear principal harmonic at the respiration frequency. The data are related to the study in [1], and the data analysis results reported there should be considered as a reference point. The data presented here have been deposited to the web site of The University of California at Irvine (UCI) Machine Learning Repository (https://archive.ics.uci.edu/ml/datasets/Gas+sensor+array+under+flow+modulation). The code repository for reproducible analysis applied to the data is hosted at the GutHub web site (https://github.com/variani/pulmon). The data and code can be used upon citation of [1].

  4. Gas hydrate, fluid flow and free gas: Formation of the bottom-simulating reflector

    NASA Astrophysics Data System (ADS)

    Haacke, R. Ross; Westbrook, Graham K.; Hyndman, Roy D.

    2007-09-01

    Gas hydrate in continental margins is commonly indicated by a prominent bottom-simulating seismic reflector (BSR) that occurs a few hundred metres below the seabed. The BSR marks the boundary between sediments containing gas hydrate above and free gas below. Most of the reflection amplitude is caused by the underlying free gas. Gas hydrate can occur without a BSR, however, and the controls on its formation are not well understood. Here we describe two complementary mechanisms for free gas accumulation beneath the gas hydrate stability zone (GHSZ). The first is the well-recognised hydrate recycling mechanism that generates gas from dissociating hydrate when the base of the GHSZ moves upward relative to hydrate-bearing sediment. The second is a recently identified mechanism in which the relationship between the advection and diffusion of dissolved gas with the local solubility curve allows the liquid phase to become saturated in a thick layer beneath the GHSZ when hydrate is present near its base. This mechanism for gas production (called the solubility-curvature mechanism) is possible in systems where the influence of diffusion becomes important relative to the influence of advection and where the gas-water solubility decreases to a minimum several hundred metres below the GHSZ. We investigate a number of areas in which gas hydrate occurs to determine where gas formation is dominated by the solubility-curvature mechanism and where it is dominated by hydrate recycling. We show that the former is dominant in areas with low rates of upward fluid flow (such as old, rifted continental margins), low rates of seafloor uplift, and high geothermal gradient and/or pressure. Conversely, free-gas formation is dominated by hydrate recycling where there are rapid rates of upward fluid flow and seabed uplift (such as in subduction zone accretionary wedges). Using these two mechanisms to investigate the formation of free gas beneath gas hydrate in continental margins, we are able

  5. Toward the improved simulation of microscale gas flow

    NASA Astrophysics Data System (ADS)

    McNenly, Matthew James

    2007-12-01

    Recent interest in fluidic micro-electro-mechanical systems (MEMS) in gaseous environments has increased the need for accurate simulation techniques to aid in their design process. Many fluidic MEMS operate in a low-speed non-equilibrium gas flow regime that is challenging to simulate both accurately and efficiently. Classic computational fluid dynamics techniques (e.g. Navier-Stokes simulation) are based on the assumption that the fluid behaves as a continuum. This assumption, however, becomes increasingly less accurate as the local flow conditions deviate further from local thermodynamic equilibrium. Alternatively, it is possible to achieve an accurate approximation of non-equilibrium gas flows using particle-based methods (e.g. DSMC), but the resulting simulations are much more computationally expensive than the continuum-based method. In fact, for the very low speeds commonly found in fluidic MEMS, the slow convergence of the DSMC solution can lead to intractably long computation times on all but the largest supercomputers. Two different approaches are pursued in this investigation, in an effort to design a physically accurate and computationally efficient simulation of low-speed, non-equilibrium flows. The first approach constructs new empirical models to correct the error in the Navier-Stokes simulation in the transition regime due to the appreciable deviation from local thermodynamic equilibrium. The empirically corrected Navier-Stokes simulation is not actually predicting strongly non-equilibrium gas flows; however, it is shown to be a useful analysis tool in certain design situations. The second more novel approach develops an original quasi-Monte Carlo (QMC) particle simulation that retains the physical accuracy of the DSMC method while at the same time achieving a faster (near-linear) convergence rate. The design of a QMC method is far more complex in general than a Monte Carlo method for the same problem. Further, no known QMC particle simulation has

  6. Dual exposure interferometry. [gas dynamics and flow visualization

    NASA Technical Reports Server (NTRS)

    Smeets, G.; George, A.

    1982-01-01

    The application of dual exposure differential interferometry to gas dynamics and flow visualization is discussed. A differential interferometer with Wallaston prisms can produce two complementary interference fringe systems, depending on the polarization of the incident light. If these two systems are superimposed on a film, with one exposure during a phenomenon, the other before or after, the phenomenon will appear on a uniform background. By regulating the interferometer to infinite fringe distance, a resolution limit of approximately lambda/500 can be obtained in the quantitative analysis of weak phase objects. This method was successfully applied to gas dynamic investigations.

  7. Flow pattern and pressure drop of vertical upward gas-liquid flow in sinusoidal wavy channels

    SciTech Connect

    Nilpueng, Kitti; Wongwises, Somchai

    2006-06-15

    Flow patterns and pressure drop of upward liquid single-phase flow and air-water two-phase flow in sinusoidal wavy channels are experimentally studied. The test section is formed by a sinusoidal wavy wall of 1.00 m length with a wave length of 67.20mm, an amplitude of 5.76mm. Different phase shifts between the side walls of the wavy channel of 0{sup o}, 90{sup o} and 180{sup o} are investigated. The flow phenomena, which are bubbly flow, slug flow, churn flow, and dispersed bubbly flow are observed and recorded by high-speed camera. When the phase shifts are increased, the onset of the transition from the bubbly flow to the churn flow shifts to a higher value of superficial air velocity, and the regions of the slug flow and the churn flow are smaller. In other words, the regions of the bubbly flow and the dispersed bubbly flow are larger as the phase shift increases. The slug flow pattern is only found in the test sections with phase shifts of 0{sup o} and 90{sup o}. Recirculating gas bubbles are always found in the troughs of the corrugations. The recirculating is higher when the phase shifts are larger. The relationship between the two-phase multipliers calculated from the measured pressure drops, and the Martinelli parameter is compared with the Lockhart-Martinelli correlation. The correlation in the case of turbulent-turbulent condition is shown to fit the data very well for the phase shift of 0{sup o} but shows greater deviation when the phase shifts are higher. (author)

  8. PREFACE: 1st European Conference on Gas Micro Flows (GasMems 2012)

    NASA Astrophysics Data System (ADS)

    Frijns, Arjan; Valougeorgis, Dimitris; Colin, Stéphane; Baldas, Lucien

    2012-05-01

    The aim of the 1st European Conference on Gas Micro Flows is to advance research in Europe and worldwide in the field of gas micro flows as well as to improve global fundamental knowledge and to enable technological applications. Gas flows in microsystems are of great importance and touch almost every industrial field (e.g. fluidic microactuators for active control of aerodynamic flows, vacuum generators for extracting biological samples, mass flow and temperature micro-sensors, pressure gauges, micro heat-exchangers for the cooling of electronic components or for chemical applications, and micro gas analyzers or separators). The main characteristic of gas microflows is their rarefaction, which for device design often requires modelling and simulation both by continuous and molecular approaches. In such flows various non-equilibrium transport phenomena appear, while the role played by the interaction between the gas and the solid device surfaces becomes essential. The proposed models of boundary conditions often need an empirical adjustment strongly dependent on the micro manufacturing technique. The 1st European Conference on Gas Micro Flows is organized under the umbrella of the recently established GASMEMS network (www.gasmems.eu/) consisting of 13 participants and six associate members. The main objectives of the network are to structure research and train researchers in the fields of micro gas dynamics, measurement techniques for gaseous flows in micro experimental setups, microstructure design and micro manufacturing with applications in lab and industry. The conference takes place on June 6-8 2012, at the Skiathos Palace Hotel, on the beautiful island of Skiathos, Greece. The conference has received funding from the European Community's Seventh Framework Programme FP7/2007-2013 under grant agreement ITN GASMEMS no. 215504. It owes its success to many people. We would like to acknowledge the support of all members of the Scientific Committee and of all

  9. Synthesis of nanocrystalline material by sputtering and laser ablation at low temperatures

    NASA Astrophysics Data System (ADS)

    Ayyub, P.; Chandra, R.; Taneja, P.; Sharma, A. K.; Pinto, R.

    Physical vapor deposition techniques such as sputtering and laser ablation - which are very commonly used in thin film technology - appear to hold much promise for the synthesis of nanocrystalline thin films as well as loosely aggregated nanoparticles. We present a systematic study of the process parameters that facilitate the growth of nanocrystalline metals and oxides. The systems studied include TiO2, ZnO, γ-Al2O3, Cu2O, Ag and Cu. The mean particle size and crystallographic orientation are influenced mainly by the sputtering power, the substrate temperature and the nature, pressure and flow rate of the sputtering gas. In general, nanocrystalline thin films were formed at or close to 300 K, while loosely adhering nanoparticles were deposited at lower temperatures.

  10. Multi-Scale Modeling of Hypersonic Gas Flow

    NASA Astrophysics Data System (ADS)

    Boyd, Iain D.

    On March 27, 2004, NASA successfully flew the X-43A hypersonic test flight vehicle at a velocity of 5000 mph to break the aeronautics speed record that had stood for over 35 years. The final flight of the X-43A on November 16, 2004 further increased the speed record to 6,600 mph which is almost ten times the speed of sound. The very high speed attainable by hypersonic airplanes could revolutionize air travel by dramatically reducing inter-continental flight times. For example, a hypersonic flight from New York to Sydney, Australia, a distance of 10,000 miles, would take less than 2 h. Reusable hypersonic vehicles are also being researched to significantly reduce the cost of access to space. Computer modeling of the gas flows around hypersonic vehicles will play a critical part in their development. This article discusses the conditions that can prevail in certain hypersonic gas flows that require a multi-scale modeling approach.

  11. Gas permeation through nanoporous membranes in the transitional flow region

    NASA Astrophysics Data System (ADS)

    Petukhov, D. I.; Eliseev, A. A.

    2016-02-01

    An experimental study on the permeability of anodic alumina (20-120 nm) and track-etched (30 nm) nanoporous membranes for different gases in the transitional flow regime is reported in the range of Knudsen numbers from 0.1 to 10. A significant variation (up to 30%) of the membrane permeance for different gases at the same Knudsen numbers is reported with certainty. It is established that this discrepancy relates to a molecule’s effective collision area, which is poorly described in the frameworks of conventional gas permeation models. Two models are proposed for the description of the effect: self-diffusion of penetrate gases due to intermolecular collisions and enhancement of the slip flow contribution due to tangential momentum accommodation growth with the decrease of a molecule’s effective collision area. The best fit parameters for the simultaneous fit of the experimental data with different models for 30 membrane-gas pairs are given.

  12. Emission control valve with gas flow shut-off

    SciTech Connect

    Betterton, J.T.; Glover, A.H.; McKee, T.S.; Romanczuk, C.S.

    1990-03-06

    This patent describes, in an internal combustion engine, a crankcase gas flow control device located between the engine crankcase and the engine fuel-air induction. It comprises: a hollow housing, an apertured member supported at its outer edge by the housing. The apertured member forming an inlet and having an annular seating surface about the inlet aperture which faces the interior of the housing; a rod extending through the housing coaxially with the apertured inlet. The inlet forming member has a central boss portion engaging and supporting an end of the rod; a valve element in the housing and encircling the rod, the valve having a closed end normally seated against the seating surface to block gas flow through the inlet aperture; a coil type spring having one end axially fixed to the rod and another end engaging the valve element for yieldably urging the closed end against the seating surface.

  13. Gaseous sodium sulfate formation in flames and flowing gas environments

    NASA Technical Reports Server (NTRS)

    Stearns, C. A.; Miller, R. A.; Kohl, F. J.; Fryburg, G. C.

    1977-01-01

    Formation of Na2SO4(g) in flames and hot flowing gas systems was studied by high pressure, free-jet expansion, modulated molecular beam mass spectrometric sampling. Fuel-lean CH4-O2 flames doped with SO2, H2O and NaCl yielded the gaseous Na2SO4 molecule in residence times of less than one millisecond. Intermediate species NaSO2(g) and NaSO3(g) were also observed and measured. Composition profiles were obtained for all reaction products. Nonflame flowing gas experiments showed that Na2SO4 and NaSO3 gaseous molecules were formed at 1140 C in mixtures of O2, H2O(g), SO2 and NaCl(g). Experimental results are compared with calculated equilibrium thermodynamic predictions.

  14. Theory of Gas Injection: Interaction of Phase Behavior and Flow

    NASA Astrophysics Data System (ADS)

    Dindoruk, B.

    2015-12-01

    The theory of gas injection processes is a central element required to understand how components move and partition in the reservoir as one fluid is displacing another (i.e., gas is displacing oil). There is significant amount of work done in the area of interaction of phase-behavior and flow in multiphase flow conditions. We would like to present how the theory of gas injection is used in the industry to understand/design reservoir processes in various ways. The tools that are developed for the theory of gas injection originates from the fractional flow theory, as the first solution proposed by Buckley-Leveret in 1940's, for water displacing oil in porous media. After 1960's more and more complex/coupled equations were solved using the initial concept(s) developed by Buckley-Leverett, and then Welge et al. and others. However, the systematic use of the fractional flow theory for coupled set of equations that involves phase relationships (EOS) and phase appearance and disappearance was mainly due to the theory developed by Helfferich in early 80's (in petroleum literature) using method of characteristics primarily for gas injection process and later on by the systematic work done by Orr and his co-researchers during the last two decades. In this talk, we will present various cases that use and extend the theory developed by Helfferich and others (Orr et al., Lake et al. etc.). The review of various injection systems reveals that displacement in porous media has commonalities that can be represented with a unified theory for a class of problems originating from the theory of gas injection (which is in a way generalized Buckley-Leverett problem). The outcome of these solutions can be used for (and are not limited to): 1) Benchmark solutions for reservoir simulators (to quantify numerical dispersion, test numerical algorithms) 2) Streamline simulators 3) Design of laboratory experiments and their use (to invert the results) 4) Conceptual learning and to investigate

  15. Numerical simulation of the countercurrent flow in a gas centrifuge

    SciTech Connect

    Cloutman, L.D.; Gentry, R.A.

    1981-01-01

    A finite difference method is presented for the numerical simulation of the axisymmetric countercurrent flows in gas centrifuge. A time-marching technique is used to relax an arbitrary initial condition to the desired steady-state solution. All boundary layers may be resolved, and nonlinear effects may be included. Numerical examples are presented. It is concluded that this technique is capable of accurately predicting the performance of a wide variety of machines under all operating conditions of interest.

  16. Liquid and liquid–gas flows at all speeds

    SciTech Connect

    LeMartelot, S.; Nkonga, B.; Saurel, R.

    2013-12-15

    All speed flows and in particular low Mach number flow algorithms are addressed for the numerical approximation of the Kapila et al. [1] multiphase flow model. This model is valid for fluid mixtures evolving in mechanical equilibrium but out of temperature equilibrium and is efficient for material interfaces computation separating miscible and non-miscible fluids. In this context, the interface is considered as a numerically diffused zone, captured as well as all present waves (shocks, expansion waves). The same flow model can be used to solve cavitating and boiling flows [2]. Many applications occurring with liquid–gas interfaces and cavitating flows involve a very wide range of Mach number, from 10{sup −3} to supersonic (and even hypersonic) conditions with respect to the mixture sound speed. It is thus important to address numerical methods free of restrictions regarding the Mach number. To do this, a preconditioned Riemann solver is built and embedded into the Godunov explicit scheme. It is shown that this method converges to exact solutions but needs too small time steps to be efficient. An implicit version is then derived, first in one dimension and second in the frame of 2D unstructured meshes. Two-phase flow preconditioning is then addressed in the frame of the Saurel et al. [3] algorithm. Modifications of the preconditioned Riemann solver are needed and detailed. Convergence of both single phase and two-phase numerical solutions are demonstrated with the help of single phase and two-phase steady nozzle flow solutions. Last, the method is illustrated by the computation of real cavitating flows in Venturi nozzles. Vapour pocket size and instability frequencies are reproduced by the model and method without using any adjustable parameter.

  17. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation...

  18. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation...

  19. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Gas meter or flow instrumentation... ENGINES Test Procedures § 92.117 Gas meter or flow instrumentation calibration, particulate measurement. (a) Sampling for particulate emissions requires the use of gas meters or flow instrumentation...

  20. Gas and liquid fuel injection into an enclosed swirling flow

    NASA Astrophysics Data System (ADS)

    Ahmad, N. T.; Andrews, G. E.

    1984-06-01

    The use of swirler air for atomization has been tested with direct central propane injection and with direct central kerosene and gas oil injection, and its results have been compared with those for nonswirling flow systems under the same conditions. Direct propane injection results in a major extension of stability limits, by comparison to results for premixing, while with liquid fuel injection the stability limits are generally worse than for premixed fuel and air. This may be due to the action of the centrifugal forces on the liquid droplets in the swirl flow, which results in outer swirl flow vaporization and weaker mixtures in the core recirculation region than would be the case for propane injection. A comparison with nonswirling system performance indicated that all emission levels were higher with swirl for propane.

  1. Granular flow in Dorfan Impingo filter for gas cleanup

    SciTech Connect

    Hsiau, S.S.; Smid, J.; Tsai, H.H.; Kuo, J.T.; Chou, C.S.

    1999-07-01

    Inside a two-dimensional model of the louvered Drofan Impingo panel with transparent front and rear walls, the velocity fields of filter granules without gas cross flow were observed. The PE beads with diameter of 6 mm were used as filter granules. The filter bed was filled with beads continuously and circulated until the granular flows inside the panel reached the steady state condition. In the moving granular bed, there is a central fast flowing core of filter granules surrounded by large quasi-stagnant zones located close to the louver walls. The existence of quasi-stagnant zones may result in the dust plugging problems. The velocity fields of filter granules are plotted for three different louver geometries.

  2. Modeling of information flows in natural gas storage facility

    NASA Astrophysics Data System (ADS)

    Ranjbari, Leyla; Bahar, Arifah; Aziz, Zainal Abdul

    2013-09-01

    The paper considers the natural-gas storage valuation based on the information-based pricing framework of Brody-Hughston-Macrina (BHM). As opposed to many studies which the associated filtration is considered pre-specified, this work tries to construct the filtration in terms of the information provided to the market. The value of the storage is given by the sum of the discounted expectations of the cash flows under risk-neutral measure, conditional to the constructed filtration with the Brownian bridge noise term. In order to model the flow of information about the cash flows, we assume the existence of a fixed pricing kernel with liquid, homogenous and incomplete market without arbitrage.

  3. A gas flow indicator for portable life support systems

    NASA Technical Reports Server (NTRS)

    Bass, R. L., III; Schroeder, E. C.

    1975-01-01

    A three-part program was conducted to develop a gas flow indicator (GFI) to monitor ventilation flow in a portable life support system. The first program phase identified concepts which could potentially meet the GFI requirements. In the second phase, a working breadboard GFI, based on the concept of a pressure sensing diaphragm-aneroid assembly connected to a venturi, was constructed and tested. Extensive testing of the breadboard GFI indicated that the design would meet all NASA requirements including eliminating problems experienced with the ventilation flow sensor used in the Apollo program. In the third program phase, an optimized GFI was designed by utilizing test data obtained on the breadboard unit. A prototype unit was constructed using prototype materials and fabrication techniques, and performance tests indicated that the prototype GFI met or exceeded all requirements.

  4. Measurements of gas/oil free surface deformation caused by parallel gas flow

    NASA Astrophysics Data System (ADS)

    Matsunaga, T.; Mialdun, A.; Nishino, K.; Shevtsova, V.

    2012-06-01

    Flow-induced dynamic free-surface deformations are experimentally studied in a confined liquid volume of 5cSt silicone oil (Prandtl number Pr = 68). The geometry of the problem is a liquid column concentrically surrounded by an annular gas channel. A gas stream entering the duct from the top or bottom entrains the motionless liquid. The dynamic deformation of the gas-liquid interface is caused by a steady axisymmetric shear-driven flow. The experiments are performed in normal gravity conditions and the static deformation of a liquid bridge interface is unavoidable. The magnitude and shape of the dynamic surface deformation are analyzed using optical measurements with a comprehensive treatment of the images. The deviation of the free surface shape from the corresponding equilibrium profile is determined with an uncertainty of about 0.1 μm. The order of magnitude of the interface deformation is proportional to the capillary number, which is defined as the ratio of the viscous force per unit area to the capillary pressure. The study is performed for a large range of volumes and aspect ratios as well as for different gas velocities. As a general trend, the dynamic deformation grows with the gas velocity, which plays the role of a driving force, but a linear dependence is not observed for all volume ratios, despite the small Reynolds numbers, 280 < Reg < 560. The dynamic deformation displays a strong dependence on the liquid volume ratio and the direction of the gas stream parallel to the interface. When the gas flow is directed against gravity, the largest interface deformations are observed at the smallest volumes among the analyzed ones. In contrast, when the gas stream is aligned with gravity, then the deformations decrease with a decrease in the volume ratio, at a certain value attaining zero (vanishing) and then changing sign.

  5. Gas diffusion optic flow calculation and its applications in gas cloud infrared imaging

    NASA Astrophysics Data System (ADS)

    Liu, Shao-hua; Luo, Xiu-li; Wang, Ling-xue; Cai, Yi

    2015-11-01

    Motion detection frequently employs Optic Flow to get the velocity of solid targets in imaging sequences. This paper suggests calculate the gas diffusion velocity in infrared gas leaking videos by optic flow algorithms. Gas target is significantly different from solid objects, which has variable margin and gray values in diffusion. A series of tests with various scenes and leakage rate were performed to compare the effect of main stream methods, such as Farneback algorithm, PyrLK and BM algorithm. Farneback algorithm seems to have the best result in those tests. Besides, the robustness of methods used in uncooled infrared imaging may decline seriously for the low resolution, big noise and poor contrast ratio. This research adopted a special foreground detection method (FDM) and spectral filtering technique to address this issue. FDM firstly computes corresponding sample sets of each pixel, and uses the background based on the sets to make a correlation analysis with the current frame. Spectral filtering technique means get two or three images in different spectrum by band pass filters, and show a better result by mixing those images. In addition, for Optic Flow methods have ability to precisely detect directional motion and to ignore the nondirectional one, these methods could be employed to highlight the gas area and reduce the background noise. This paper offers a credible way for obtaining the diffusion velocity and resolves the robust troubles in practical application. In the meanwhile, it is an exploration of optic flow in varied shape target detection.

  6. Computer modeling of gas flow and gas loading of rock in a bench blasting environment

    SciTech Connect

    Preece, D.S.; Baer, M.R. ); Knudsen, S.D. )

    1991-01-01

    Numerical modeling can contribute greatly to an understanding of the physics involved in the blasting process. This paper will describe the latest enhancements to the blast modeling code DMC (Distinct Motion Code) (Taylor and Preece, 1989) and will demonstrate the ability of DMC to model gas flow and rock motion in a bench blasting environment. DMC has been used previously to model rock motion associated with blasting in a cratering environment (Preece and Taylor, 1990) and in confined volume blasting associated with in-situ oil shale retorting (Preece, 1990 a b). These applications of DMC treated the explosive loading as force versus time functions on specific spheres which were adjusted to obtain correct face velocities. It was recognized that a great need in explosives modeling was the coupling of an ability to simulate gas flow with the rock motion simulation capability of DMC. This was accomplished by executing a finite difference code that computes gas flow through a porous media (Baer and Gross, 1989) in conjunction with DMC. The marriage of these two capabilities has been documented by Preece and Knudsen, 1991. The capabilities that have been added recently to DMC and which will be documented in this paper include: (1) addition of a new equation of state for the explosive gases; (2) modeling of gas flow and sphere loading in a bench environment. 8 refs., 5 figs.

  7. Shape of gas flow paths causes power law tailing

    NASA Astrophysics Data System (ADS)

    Kawanishi, T.; Sakami, A.; Hayashi, Y.

    2004-12-01

    In soil and/or groundwater remediation, we often see prolonged tailings: continuous outflow of low concentration pollutants for very long time, and in many cases power low behavior of late-time time-concentration curves. We considered that this kind of tailing can be caused by the shape of the gaseous flow introduced in saturated/unsaturated porous media. When gas is introduced to porous media, like air-sparging or soil vapor extraction, the shape of the gas flow path would be tree-like, or to some extent "fractal." So, there would be a distribution of the distance that a solute would have to travel by diffusion before getting to a gas/water interface, and we might expect that the distribution of this "diffusion distance" would be power-law-like. In order to see if tailing can be caused by this mechanism, simple column experiments were carried out. A column, 64 mm in inner diameter and 240 mm in height, was prepared and was packed with 1mm diameter glass beads. Nitrogen gas containing 5 % CO2 and 5% He was supplied from the bottom of the column, and after the water in the column is approximately saturated with CO2, the sparging gas was changed to pure nitrogen. The CO2 and He concentrations in the effluent gas was monitored and recorded. As the result, we saw tailing: the double-log plots of the concentration vs. time relationship was practically linear, and the absolute value of the slope in the double-log charts were 1.28, 0.95 and 0.83 according to the gas flow rates of 40, 80 and 120 ml/min, respectively. Slope less than 1.00 showed that these tailings cannot be explained by Freundlich-type adsorption behavior. Model analysis showed that this power low time-concentration behavior with the slope of approximately -1.0 can be explained by the power law distribution of diffusion distance \\textit{a} with PDF p(\\textit{a}) proportional to \\textit{a}^{-1}.

  8. Long-term flow monitoring of submarine gas emanations

    NASA Astrophysics Data System (ADS)

    Spickenbom, K.; Faber, E.; Poggenburg, J.; Seeger, C.

    2009-04-01

    One of the Carbon Capture and Storage (CCS) strategies currently under study is the sequestration of CO2 in sub-seabed geological formations. Even after a thorough review of the geological setting, there is the possibility of leaks from the reservoirs. As part of the EU-financed project CO2ReMoVe (Research, Monitoring, Verification), which aims to develop innovative research and technologies for monitoring and verification of carbon dioxide geological storage, we are working on the development of submarine long-term gas flow monitoring systems. Technically, however, these systems are not limited to CO2 but can be used for monitoring of any free gas emission (bubbles) on the seafloor. The basic design of the gas flow sensor system was derived from former prototypes developed for monitoring CO2 and CH4 on mud volcanoes in Azerbaijan. This design was composed of a raft floating on the surface above the gas vent to collect the bubbles. Sensors for CO2 flux and concentration and electronics for data storage and transmission were mounted on the raft, together with battery-buffered solar panels for power supply. The system was modified for installation in open sea by using a buoy instead of a raft and a funnel on the seafloor to collect the gas, which is then guided above water level through a flexible tube. Besides some technical problems (condensed water in the tube, movement of the buoys due to waves leading to biased measurement of flow rates), this setup provides a cost-effective solution for shallow waters. However, a buoy interferes with ship traffic, and it is also difficult to adapt this design to greater water depths. These requirements can best be complied by a completely submersed system. To allow unattended long-term monitoring in a submarine environment, such a system has to be extremely durable. Therefore, we focussed on developing a mechanically and electrically as simple setup as possible, which has the additional advantage of low cost. The system

  9. Viewing inside Pyroclastic Flows - Large-scale Experiments on hot pyroclast-gas mixture flows

    NASA Astrophysics Data System (ADS)

    Breard, E. C.; Lube, G.; Cronin, S. J.; Jones, J.

    2014-12-01

    Pyroclastic density currents are the largest threat from volcanoes. Direct observations of natural flows are persistently prevented because of their violence and remain limited to broad estimates of bulk flow behaviour. The Pyroclastic Flow Generator - a large-scale experimental facility to synthesize hot gas-particle mixture flows scaled to pyroclastic flows and surges - allows investigating the physical processes behind PDC behaviour in safety. The ability to simulate natural eruption conditions and to view and measure inside the hot flows allows deriving validation and calibration data sets for existing numerical models, and to improve the constitutive relationships necessary for their effective use as powerful tools in hazard assessment. We here report on a systematic series of large-scale experiments on up to 30 ms-1 fast, 2-4.5 m thick, 20-35 m long flows of natural pyroclastic material and gas. We will show high-speed movies and non-invasive sensor data that detail the internal structure of the analogue pyroclastic flows. The experimental PDCs are synthesized by the controlled 'eruption column collapse' of variably diluted suspensions into an instrumented channel. Experiments show four flow phases: mixture acceleration and dilution during free fall; impact and lateral blasting; PDC runout; and co-ignimbrite cloud formation. The fully turbulent flows reach Reynolds number up to 107 and depositional facies similar to natural deposits. In the PDC runout phase, the shear flows develop a four-partite structure from top to base: a fully turbulent, strongly density-stratified ash cloud with average particle concentrations <<1vol%; a transient, turbulent dense suspension region with particle concentrations between 1 and 10 vol%; a non-turbulent, aerated and highly mobile dense underflows with particle concentrations between 40 and 50 vol%; and a vertically aggrading bed of static material. We characterise these regions and the exchanges of energy and momentum

  10. Magnetic roller gas gate employing transonic sweep gas flow to isolate regions of differing gaseous composition or pressure

    DOEpatents

    Doehler, Joachim

    1994-12-20

    Disclosed herein is an improved gas gate for interconnecting regions of differing gaseous composition and/or pressure. The gas gate includes a narrow, elongated passageway through which substrate material is adapted to move between said regions and inlet means for introducing a flow of non-contaminating sweep gas into a central portion of said passageway. The gas gate is characterized in that the height of the passageway and the flow rate of the sweep gas therethrough provides for transonic flow of the sweep gas between the inlet means and at least one of the two interconnected regions, thereby effectively isolating one region, characterized by one composition and pressure, from another region, having a differing composition and/or pressure, by decreasing the mean-free-path length between collisions of diffusing species within the transonic flow region. The gas gate preferably includes a manifold at the juncture point where the gas inlet means and the passageway interconnect.

  11. Wavy-to-slug flow transition in slightly inclined gas-liquid pipe flow

    SciTech Connect

    Grolman, E.; Commandeur, N.C.J.; Baat, E.C. de; Fortuin, J.M.H.

    1996-04-01

    A process-engineering model is presented for the stratified-wavy-to-intermittent (SW-I) flow-pattern transition in slightly inclined gas-liquid pipe flow. The main parameter for predicting (in)stability of wavy flow in inclined pipes is the average liquid holdup, which was found to reach a maximum, critical value at flow-pattern transition. Observed values of the critical liquid holdup vary between 0.07 and 0.42, depending on pipe diameter, angle of inclination and transport properties of the gas-liquid system. Measurements were performed in transparent glass pipes of 26- and 51-mm dia., at ten angles of inclination (0.1{degree} {le} {beta} {le} 6.0{degree}), using air/water and air/tetradecane (n-C{sub 14}H{sub 30}) systems at atmospheric pressure. Flow-pattern maps are presented for selected angles of inclination, showing excellent agreement between predicted and observed flow-pattern boundaries.

  12. Direct comparative study on the energy level alignments in unoccupied/occupied states of organic semiconductor/electrode interface by constructing in-situ photoemission spectroscopy and Ar gas cluster ion beam sputtering integrated analysis system

    SciTech Connect

    Yun, Dong-Jin Chung, JaeGwan; Kim, Yongsu; Park, Sung-Hoon; Kim, Seong-Heon; Heo, Sung

    2014-10-21

    Through the installation of electron gun and photon detector, an in-situ photoemission and damage-free sputtering integrated analysis system is completely constructed. Therefore, this system enables to accurately characterize the energy level alignments including unoccupied/occupied molecular orbital (LUMO/HOMO) levels at interface region of organic semiconductor/electrode according to depth position. Based on Ultraviolet Photoemission Spectroscopy (UPS), Inverse Photoemission Spectroscopy (IPES), and reflective electron energy loss spectroscopy, the occupied/unoccupied state of in-situ deposited Tris[4-(carbazol-9-yl)phenyl]amine (TCTA) organic semiconductors on Au (E{sub LUMO}: 2.51 eV and E{sub HOMO}: 1.35 eV) and Ti (E{sub LUMO}: 2.19 eV and E{sub HOMO}: 1.69 eV) electrodes are investigated, and the variation of energy level alignments according to work function of electrode (Au: 4.81 eV and Ti: 4.19 eV) is clearly verified. Subsequently, under the same analysis condition, the unoccupied/occupied states at bulk region of TCTA/Au structures are characterized using different Ar gas cluster ion beam (Ar GCIB) and Ar ion sputtering processes, respectively. While the Ar ion sputtering process critically distorts both occupied and unoccupied states in UPS/IPES spectra, the Ar GCIB sputtering process does not give rise to damage on them. Therefore, we clearly confirm that the in-situ photoemission spectroscopy in combination with Ar GCIB sputtering allows of investigating accurate energy level alignments at bulk/interface region as well as surface region of organic semiconductor/electrode structure.

  13. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200...

  14. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200...

  15. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200...

  16. 42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied by a constant-flow device only, the rate of flow shall be at least 3 liters per minute for the...

  17. 42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied by a constant-flow device only, the rate of flow shall be at least 3 liters per minute for the...

  18. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Gas flow test; open-circuit apparatus. 84.93...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be performed on all open-circuit apparatus. (b) The flow from the apparatus shall be greater than 200...

  19. Data set from gas sensor array under flow modulation☆

    PubMed Central

    Ziyatdinov, Andrey; Fonollosa, Jordi; Fernández, Luis; Gutiérrez-Gálvez, Agustín; Marco, Santiago; Perera, Alexandre

    2015-01-01

    Recent studies in neuroscience suggest that sniffing, namely sampling odors actively, plays an important role in olfactory system, especially in certain scenarios such as novel odorant detection. While the computational advantages of high frequency sampling have not been yet elucidated, here, in order to motivate further investigation in active sampling strategies, we share the data from an artificial olfactory system made of 16 MOX gas sensors under gas flow modulation. The data were acquired on a custom set up featured by an external mechanical ventilator that emulates the biological respiration cycle. 58 samples were recorded in response to a relatively broad set of 12 gas classes, defined from different binary mixtures of acetone and ethanol in air. The acquired time series show two dominant frequency bands: the low-frequency signal corresponds to a conventional response curve of a sensor in response to a gas pulse, and the high-frequency signal has a clear principal harmonic at the respiration frequency. The data are related to the study in [1], and the data analysis results reported there should be considered as a reference point. The data presented here have been deposited to the web site of The University of California at Irvine (UCI) Machine Learning Repository (https://archive.ics.uci.edu/ml/datasets/Gas+sensor+array+under+flow+modulation). The code repository for reproducible analysis applied to the data is hosted at the GutHub web site (https://github.com/variani/pulmon). The data and code can be used upon citation of [1]. PMID:26217733

  20. Noble gas loss may indicate groundwater flow across flow barriers in southern Nevada

    USGS Publications Warehouse

    Thomas, J.M.; Bryant, Hudson G.; Stute, M.; Clark, J.F.

    2003-01-01

    Average calculated noble gas temperatures increase from 10 to 22??C in groundwater from recharge to discharge areas in carbonate-rock aquifers of southern Nevada. Loss of noble gases from groundwater in these regional flow systems at flow barriers is the likely process that produces an increase in recharge noble gas temperatures. Emplacement of low permeability rock into high permeability aquifer rock and the presence of low permeability shear zones reduce aquifer thickness from thousands to tens of meters. At these flow barriers, which are more than 1,000 m lower than the average recharge altitude, noble gases exsolve from the groundwater by inclusion in gas bubbles formed near the barriers because of greatly reduced hydrostatic pressure. However, re-equilibration of noble gases in the groundwater with atmospheric air at the low altitude spring discharge area, at the terminus of the regional flow system, cannot be ruled out. Molecular diffusion is not an important process for removing noble gases from groundwater in the carbonate-rock aquifers because concentration gradients are small.

  1. Supersonic Flow of Chemically Reacting Gas-Particle Mixtures. Volume 2: RAMP - A Computer Code for Analysis of Chemically Reacting Gas-Particle Flows

    NASA Technical Reports Server (NTRS)

    Penny, M. M.; Smith, S. D.; Anderson, P. G.; Sulyma, P. R.; Pearson, M. L.

    1976-01-01

    A computer program written in conjunction with the numerical solution of the flow of chemically reacting gas-particle mixtures was documented. The solution to the set of governing equations was obtained by utilizing the method of characteristics. The equations cast in characteristic form were shown to be formally the same for ideal, frozen, chemical equilibrium and chemical non-equilibrium reacting gas mixtures. The characteristic directions for the gas-particle system are found to be the conventional gas Mach lines, the gas streamlines and the particle streamlines. The basic mesh construction for the flow solution is along streamlines and normals to the streamlines for axisymmetric or two-dimensional flow. The analysis gives detailed information of the supersonic flow and provides for a continuous solution of the nozzle and exhaust plume flow fields. Boundary conditions for the flow solution are either the nozzle wall or the exhaust plume boundary.

  2. Analytical flow/thermal modeling of combustion gas flows in Redesigned Solid Rocket Motor test joints

    NASA Technical Reports Server (NTRS)

    Woods, G. H.; Knox, E. C.; Pond, J. E.; Bacchus, D. L.; Hengel, J. E.

    1992-01-01

    A one-dimensional analytical tool, TOPAZ (Transient One-dimensional Pipe flow AnalyZer), was used to model the flow characteristics of hot combustion gases through Redesigned Solid Rocket Motor (RSRM) joints and to compute the resultant material surface temperatures and o-ring seal erosion of the joints. The capabilities of the analytical tool were validated with test data during the Seventy Pound Charge (SPC) motor test program. The predicted RSRM joint thermal response to ignition transients was compared with test data for full-scale motor tests. The one-dimensional analyzer is found to be an effective tool for simulating combustion gas flows in RSRM joints and for predicting flow and thermal properties.

  3. Analysis of Developing Gas/liquid Two-Phase Flows

    SciTech Connect

    Elena A. Tselishcheva; Michael Z. Podowski; Steven P. Antal; Donna Post Guillen; Matthias Beyer; Dirk Lucas

    2010-06-01

    The goal of this work is to develop a mechanistically based CFD model that can be used to simulate process equipment operating in the churn-turbulent regime. The simulations were performed using a state-of-the-art computational multiphase fluid dynamics code, NPHASE–CMFD [Antal et al,2000]. A complete four-field model, including the continuous liquid field and three dispersed gas fields representing bubbles of different sizes, was first carefully tested for numerical convergence and accuracy, and then used to reproduce the experimental results from the TOPFLOW test facility at Forschungszentrum Dresden-Rossendorf e.V. Institute of Safety Research [Prasser et al,2007]. Good progress has been made in simulating the churn-turbulent flows and comparison the NPHASE-CMFD simulations with TOPFLOW experimental data. The main objective of the paper is to demonstrate capability to predict the evolution of adiabatic churn-turbulent gas/liquid flows. The proposed modelling concept uses transport equations for the continuous liquid field and for dispersed bubble fields [Tselishcheva et al, 2009]. Along with closure laws based on interaction between bubbles and continuous liquid, the effect of height on air density has been included in the model. The figure below presents the developing flow results of the study, namely total void fraction at different axial locations along the TOPFLOW facility test section. The complete model description, as well as results of simulations and validation will be presented in the full paper.

  4. Influence of electronic stopping on sputtering induced by cluster impact on metallic targets

    SciTech Connect

    Sandoval, Luis; Urbassek, Herbert M.

    2009-04-01

    Using molecular-dynamics simulation, we model the sputtering of a Au (111) crystallite induced by the impact of Au{sub 13} projectiles with total energies up to 500 keV. Due to the uncertainty of the electronic stopping of Au moving in particular at small velocities, we performed several simulations, in which the electronic stopping parameters are systematically changed. Our results demonstrate the dominating influence of the cut-off energy E{sub c}, below which the high-velocity electronic stopping of atoms is switched off in the simulation. If E{sub c} is smaller than roughly one half the cohesive energy of the target, sputtering ceases after a few ps; the spike contribution to sputtering (also called phase explosion or gas-flow contribution) is entirely quenched and the sputtering yield is up to an order of magnitude smaller than when electronic stopping is taken into account only at higher atom energies. Our results demonstrate the importance of a careful modeling of electronic stopping in simulations of spike sputtering from metals.

  5. Sputtered titanium oxynitride coatings for endosseous applications: Physical and chemical evaluation and first bioactivity assays

    NASA Astrophysics Data System (ADS)

    Banakh, Oksana; Moussa, Mira; Matthey, Joel; Pontearso, Alessandro; Cattani-Lorente, Maria; Sanjines, Rosendo; Fontana, Pierre; Wiskott, Anselm; Durual, Stephane

    2014-10-01

    Titanium oxynitride coatings (TiNxOy) are considered a promising material for applications in dental implantology due to their high corrosion resistance, their biocompatibility and their superior hardness. Using the sputtering technique, TiNxOy films with variable chemical compositions can be deposited. These films may then be set to a desired value by varying the process parameters, that is, the oxygen and nitrogen gas flows. To improve the control of the sputtering process with two reactive gases and to achieve a variable and controllable coating composition, the plasma characteristics were monitored in-situ by optical emission spectroscopy. TiNxOy films were deposited onto commercially pure (ASTM 67) microroughened titanium plates by reactive magnetron sputtering. The nitrogen gas flow was kept constant while the oxygen gas flow was adjusted for each deposition run to obtain films with different oxygen and nitrogen contents. The physical and chemical properties of the deposited films were analyzed as a function of oxygen content in the titanium oxynitride. The potential application of the coatings in dental implantology was assessed by monitoring the proliferation and differentiation of human primary osteoblasts.

  6. Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

    2016-03-01

    Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

  7. Flammable gas interlock spoolpiece flow response test report

    SciTech Connect

    Schneider, T.C., Fluor Daniel Hanford

    1997-03-24

    The purpose of this test report is to document the testing performed under the guidance of HNF-SD-WM-TC-073, {ital Flammable Gas Interlock Spoolpiece Flow Response Test Plan and Procedure}. This testing was performed for Lockheed Martin Hanford Characterization Projects Operations (CPO) in support of Rotary Mode Core Sampling jointly by SGN Eurisys Services Corporation and Numatec Hanford Company. The testing was conducted in the 305 building Engineering Testing Laboratory (ETL). NHC provides the engineering and technical support for the 305 ETL. The key personnel identified for the performance of this task are as follows: Test responsible engineering manager, C. E. Hanson; Flammable Gas Interlock Design Authority, G. P. Janicek; 305 ETL responsible manager, N. J. Schliebe; Cognizant RMCS exhauster engineer, E. J. Waldo/J. D. Robinson; Cognizant 305 ETL engineer, K. S. Witwer; Test director, T. C. Schneider. Other support personnel were supplied, as necessary, from 305/306 ETL. The testing, on the flammable Gas Interlock (FGI) system spoolpiece required to support Rotary Mode Core Sampling (RMCS) of single shell flammable gas watch list tanks, took place between 2-13-97 and 2-25-97.

  8. LIF Measurement of Interacting Gas Jet Flow with Plane Wall

    NASA Astrophysics Data System (ADS)

    Yanagi, A.; Kurihara, S.; Yamazaki, S.; Ota, M.; Maeno, K.

    2011-05-01

    Discharging rarefied gas jets in low-pressure conditions are interesting and important phenomena from an engineering point of view. For example they relate to the attitude control of the space satellite, or the semiconductor technology. The jets, however, deform to the complicated shapes by interacting with solid walls. In this paper we have performed the experiments the flow visualization as a first step by applying the LIF (Laser Induced Fluorescence) method on the jet-wall interaction. Jet is spouting out from a φ1.0 mm circular hole into the low pressure air chamber, impinging on a flat plate. The LIF visualization of interacting rarefied gas jet is carried out by using the iodine (I2) tracer and argon ion laser.

  9. Lattice gas automata for flow and transport in geochemical systems

    SciTech Connect

    Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.

    1992-05-01

    Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.

  10. Lattice gas automata for flow and transport in geochemical systems

    SciTech Connect

    Janecky, D.R.; Chen, S.; Dawson, S.; Eggert, K.C.; Travis, B.J.

    1992-01-01

    Lattice gas automata models are described, which couple solute transport with chemical reactions at mineral surfaces within pore networks. Diffusion in a box calculations are illustrated, which compare directly with Fickian diffusion. Chemical reactions at solid surfaces, including precipitation/dissolution, sorption, and catalytic reaction, can be examined with the model because hydrodynamic transport, solute diffusion and mineral surface processes are all treated explicitly. The simplicity and flexibility of the approach provides the ability to study the interrelationship between fluid flow and chemical reactions in porous materials, at a level of complexity that has not previously been computationally possible.

  11. Acoustic cross-correlation flowmeter for solid-gas flow

    NASA Astrophysics Data System (ADS)

    Sheen, S. H.; Raptis, A. C.

    1984-05-01

    An apparatus for measuring particle velocity in a solid-gas flow within a pipe is described. It includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

  12. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, S.H.; Raptis, A.C.

    1984-05-14

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals; and means for cross-correlating said first and second output signals.

  13. Acoustic cross-correlation flowmeter for solid-gas flow

    DOEpatents

    Sheen, Shuh-Haw; Raptis, Apostolos C.

    1986-01-01

    Apparatus for measuring particle velocity in a solid-gas flow within a pipe includes: first and second transmitting transducers for transmitting first and second ultrasonic signals into the pipe at first and second locations, respectively, along the pipe; an acoustic decoupler, positioned between said first and second transmitting transducers, for acoustically isolating said first and second signals from one another; first and second detecting transducers for detecting said first and second signals and for generating first and second detected signals in response to said first and second detected signals; and means for cross-correlating said first and second output signals.

  14. A new model for gas/solid pipe flow

    SciTech Connect

    Wu, Bangxian; Chang, S.L.; Lottes, S.A.; Petrick, M.

    1995-12-31

    A new model of particle turbulent dispersion in vertical gas/solid pipe flow is presented in this paper. The essence of the model is to pay more attention to the active and discrete behavior of particles in the dispersion process in non-homogeneous turbulent vertical pipe flows using two-fluid approaches. In the new model, a non-gradient type of diffusion term is included in the expression of radial particle dispersion flux; the transport equation for particle turbulent kinetic energy (PTKE) is developed and solved for its distribution; the effect of intra-particle collision is considered for the generation and dissipation of PTKE; turbulence modulation due to particle presence is taken into account. Preliminary numerical results based on this new model are also presented in this paper.

  15. Particle contamination formation in magnetron sputtering processes

    SciTech Connect

    Selwyn, G.S.; Sequeda, F.; Huang, C.

    1997-07-01

    Defects caused by particulate contamination are an important concern in the fabrication of thin film products. Often, magnetron sputtering processes are used for this purpose. Particle contamination generated during thin film processing can be detected using laser light scattering, a powerful diagnostic technique which provides real-time, {ital in situ} imaging of particles {gt}0.3 {mu}m on the target, substrate, or in the plasma. Using this technique, we demonstrate that the mechanisms for particle generation, transport, and trapping during magnetron sputter deposition are different from the mechanisms reported in previously studied plasma etch processes, due to the inherent spatial nonuniformity of magnetically enhanced plasmas. During magnetron sputter deposition, one source of particle contamination is linked to portions of the sputtering target surface exposed to weaker plasma density. There, film redeposition induces filament or nodule growth. Sputter removal of these features is inhibited by the dependence of sputter yield on angle of incidence. These features enhance trapping of plasma particles, which then increases filament growth. Eventually the growths effectively {open_quotes}short-circuit{close_quotes} the sheath, causing high currents to flow through these features. This, in turn, causes mechanical failure of the growth resulting in fracture and ejection of the target contaminants into the plasma and onto the substrate. Evidence of this effect has been observed in semiconductor fabrication and storage disk manufacturing. Discovery of this mechanism in both technologies suggests it may be universal to many sputter processes. {copyright} {ital 1997 American Vacuum Society.}

  16. Equilibrium gas flow computations. I - Accurate and efficient calculation of equilibrium gas properties

    NASA Technical Reports Server (NTRS)

    Liu, Yen; Vinokur, Marcel

    1989-01-01

    This paper treats the accurate and efficient calculation of thermodynamic properties of arbitrary gas mixtures for equilibrium flow computations. New improvements in the Stupochenko-Jaffe model for the calculation of thermodynamic properties of diatomic molecules are presented. A unified formulation of equilibrium calculations for gas mixtures in terms of irreversible entropy is given. Using a highly accurate thermo-chemical data base, a new, efficient and vectorizable search algorithm is used to construct piecewise interpolation procedures with generate accurate thermodynamic variable and their derivatives required by modern computational algorithms. Results are presented for equilibrium air, and compared with those given by the Srinivasan program.

  17. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  18. Two critical issues in Langevin simulation of gas flows

    SciTech Connect

    Zhang, Jun; Fan, Jing

    2014-12-09

    A stochastic algorithm based on the Langevin equation has been recently proposed to simulate rarefied gas flows. Compared with the direct simulation Monte Carlo (DSMC) method, the Langevin method is more efficient in simulating small Knudsen number flows. While it is well-known that the cell sizes and time steps should be smaller than the mean free path and the mean collision time, respectively, in DSMC simulations, the Langevin equation uses a drift term and a diffusion term to describe molecule movements, so no direct molecular collisions have to be modeled. This enables the Langevin simulation to proceed with a much larger time step than that in the DSMC method. Two critical issues in Langevin simulation are addressed in this paper. The first issue is how to reproduce the transport properties as that described by kinetic theory. Transport coefficients predicted by Langevin equation are obtained by using Green-Kubo formulae. The second issue is numerical scheme with boundary conditions. We present two schemes corresponding to small time step and large time step, respectively. For small time step, the scheme is similar to DSMC method as the update of positions and velocities are uncoupled; for large time step, we present an analytical solution of the hitting time, which is the crucial factor for accurate simulation. Velocity-Couette flow, thermal-Couette flow, Rayleigh-Bénard flow and wall-confined problem are simulated by using these two schemes. Our study shows that Langevin simulation is a promising tool to investigate small Knudsen number flows.

  19. A critical review of two-phase flow in gas flow channels of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Anderson, Ryan; Zhang, Lifeng; Ding, Yulong; Blanco, Mauricio; Bi, Xiaotao; Wilkinson, David P.

    Water management in PEM fuel cells has received extensive attention due to its key role in fuel cell performance. The unavoidable water, from humidified gas streams and electrochemical reaction, leads to gas-liquid two-phase flow in the flow channels of fuel cells. The presence of two-phase flow increases the complexity in water management in PEM fuel cells, which remains a challenging hurdle in the commercialization of this technology. Unique water emergence from the gas diffusion layer, which is different from conventional gas-liquid two-phase flow where water is introduced from the inlet together with the gas, leads to different gas-liquid flow behaviors, including pressure drop, flow pattern, and liquid holdup along flow field channels. These parameters are critical in flow field design and fuel cell operation and therefore two-phase flow has received increasing attention in recent years. This review emphasizes gas-liquid two-phase flow in minichannels or microchannels related to PEM fuel cell applications. In situ and ex situ experimental setups have been utilized to visualize and quantify two-phase flow phenomena in terms of flow regime maps, flow maldistribution, and pressure drop measurements. Work should continue to make the results more relevant for operating PEM fuel cells. Numerical simulations have progressed greatly, but conditions relevant to the length scales and time scales experienced by an operating fuel cell have not been realized. Several mitigation strategies exist to deal with two-phase flow, but often at the expense of overall cell performance due to parasitic power losses. Thus, experimentation and simulation must continue to progress in order to develop a full understanding of two-phase flow phenomena so that meaningful mitigation strategies can be implemented.

  20. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier–Stokes–Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165–74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  1. Dissipation process of binary gas mixtures in thermally relativistic flow

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2016-04-01

    In this paper, dissipation process of binary gas mixtures in thermally relativistic flows is discussed with focus on characteristics of diffusion flux. As an analytical object, we consider the relativistic rarefied-shock layer around a triangular prism. Numerical results for the diffusion flux are compared with the Navier-Stokes-Fourier (NSF) order approximation of the diffusion flux, which is calculated using the diffusion and thermal-diffusion coefficients by Kox et al (1976 Physica A 84 165-74). In the case of uniform flow with small Lorentz contraction, the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is roughly approximated by the NSF order approximation inside the shock wave, whereas the diffusion flux in the vicinity of a wall is markedly different from the NSF order approximation. The magnitude of the diffusion flux, which is obtained by calculating the relativistic Boltzmann equation, is similar to that of the NSF order approximation inside the shock wave, unlike the pressure deviator, dynamic pressure and heat flux, even when the Lorentz contraction in the uniform flow becomes large, because the diffusion flux does not depend on the generic Knudsen number from its definition in Eckart’s frame. Finally, the author concludes that for accuracy diffusion flux must be calculated using the particle four-flow and averaged four velocity, which are formulated using the four velocity defined by each species of hard spherical particles.

  2. Strongly coupled turbulent gas-particle flows in vertical channels

    NASA Astrophysics Data System (ADS)

    Fox, Rodney O.; Capecelatro, Jesse; Desjardins, Olivier

    2015-11-01

    Eulerian-Lagrangian (EL) simulations of strongly coupled (high mass loading) gas-particle flows in vertical channels are performed with the purpose of exploring the fundamental physics of fully developed, wall-bounded multiphase turbulence. An adaptive spatial filter is developed that accurately decomposes the total granular energy of the particles into correlated and uncorrelated components at each location in the wall-normal direction of the flow. In this manner, Reynolds- and phase-averaged (PA) two-phase turbulence statistics up to second order are reported for both phases and for three values of the PA mean fluid velocity. As expected due to the high mass loading, in all cases the turbulence production due to mean drag dominates production due to mean shear. A multiphase LRR-IP Reynolds-stress turbulence model is developed to predict the turbulent flow statistics as a function of the wall-normal distance. Using a correlation for the vertical drift velocity developed from the EL data, the turbulence model predictions agree satisfactorily with all of one-point EL statistics for the vertical channel flows, as well as for the homogeneous cluster-induced turbulence (CIT) statistics reported previously. Funded by U.S. National Science Foundation (CBET-1437865).

  3. FORCE2: A multidimensional flow program for gas solids flow theory guide

    SciTech Connect

    Burge, S.W.

    1991-05-01

    This report describes the theory and structure of the FORCE2 flow program. The manual describes the governing model equations, solution procedure and their implementation in the computer program. FORCE2 is an extension of an existing B&V multidimensional, two-phase flow program. FORCE2 was developed for application to fluid beds by flow implementing a gas-solids modeling technology derived, in part, during a joint government -- industry research program, ``Erosion of FBC Heat Transfer Tubes,`` coordinated by Argonne National Laboratory. The development of FORCE2 was sponsored by ASEA-Babcock, an industry participant in this program. This manual is the principal documentation for the program theory and organization. Program usage and post-processing of code predictions with the FORCE2 post-processor are described in a companion report, FORCE2 -- A Multidimensional Flow Program for Fluid Beds, User`s Guide. This manual is segmented into sections to facilitate its usage. In section 2.0, the mass and momentum conservation principles, the basis for the code, are presented. In section 3.0, the constitutive relations used in modeling gas-solids hydrodynamics are given. The finite-difference model equations are derived in section 4.0 and the solution procedures described in sections 5.0 and 6.0. Finally, the implementation of the model equations and solution procedure in FORCE2 is described in section 7.0.

  4. Computerized optimization of flows and temperature gradient in flow modulated comprehensive two-dimensional gas chromatography.

    PubMed

    Májek, Pavel; Krupčík, Ján; Gorovenko, Roman; Špánik, Ivan; Sandra, Pat; Armstrong, Daniel W

    2014-07-01

    Informational entropy and syentropy percent were used to optimize the flows in the first (1D) and in the second (2D) dimension ((1)Fm and (2)Fm, respectively) as well as the temperature program rate (r) for the flow modulated GC×GC-FID separation of C6-C12 aromatic hydrocarbons in a low boiling petrochemical sample. The separations were performed on a column series consisting of a 25m×0.25mm i.d.×0.2μm df of the polar ionic liquid SLB-IL 100 (1,9-di(3-vinylimidazolium)nonane bis(trifluoromethylsulfonyl)imide) in the first dimension and 5m×0.25mm i.d.×0.25μm df apolar HP-5MS (5% phenyl-95% methylpolysiloxane) in the second dimension. A dependence of a distribution of individual aromatic hydrocarbons in the 2D retention plane on the carrier gas flows ((1)Fm, and (2)Fm,) and temperature gradient (r) was examined in this study. It was found that informational entropy and synentropy percent are advantageous criteria to characterize the distribution of peaks in the 2D retention plane. Maximum informational entropy and synentropy percents correspond to the maximum distribution of C6-C12 aromatic hydrocarbons in the corresponding 2D retention plane gained by the given separation using optimized values of individual carrier gas column volume flows and the temperature rate at the temperature programmed GC×GC separations.

  5. Gas and liquid measurements in air-water bubbly flows

    SciTech Connect

    Zhou, X.; Doup, B.; Sun, X.

    2012-07-01

    Local measurements of gas- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)

  6. A study of gas flow pattern, undercutting and torch modification in variable polarity plasma arc welding

    NASA Technical Reports Server (NTRS)

    Mcclure, John C.; Hou, Haihui Ron

    1994-01-01

    A study on the plasma and shield gas flow patterns in variable polarity plasma arc (VPPA) welding was undertaken by shadowgraph techniques. Visualization of gas flow under different welding conditions was obtained. Undercutting is often present with aluminum welds. The effects of torch alignment, shield gas flow rate and gas contamination on undercutting were investigated and suggestions made to minimize the defect. A modified shield cup for the welding torch was fabricated which consumes much less shield gas while maintaining the weld quality. The current torch was modified with a trailer flow for Al-Li welding, in which hot cracking is a critical problem. The modification shows improved weldablility on these alloys.

  7. Heavy particle transport in sputtering systems

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan

    2015-09-01

    This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

  8. Use of exhaust gas as sweep flow to enhance air separation membrane performance

    DOEpatents

    Dutart, Charles H.; Choi, Cathy Y.

    2003-01-01

    An intake air separation system for an internal combustion engine is provided with purge gas or sweep flow on the permeate side of separation membranes in the air separation device. Exhaust gas from the engine is used as a purge gas flow, to increase oxygen flux in the separation device without increasing the nitrogen flux.

  9. 42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied... rated service time of the apparatus. (b) Where constant flow is used in conjunction with demand...

  10. 42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Gas flow test; closed-circuit apparatus. 84.94...-Contained Breathing Apparatus § 84.94 Gas flow test; closed-circuit apparatus. (a) Where oxygen is supplied... rated service time of the apparatus. (b) Where constant flow is used in conjunction with demand...

  11. Magnetogasdynamic Power Extraction and Flow Conditioning for a Gas Turbine

    NASA Technical Reports Server (NTRS)

    Adamovich, Igor V.; Rich, J. William; Schneider, Steven; Blankson, Isaiah

    2003-01-01

    An extension of the Russian AJAX concept to a turbojet is being explored. This magnetohydrodynamic (MHD) energy bypass engine cycle incorporating conventional gas turbine technology has MHD flow conditioning at the inlet to electromagnetically extract part of the inlet air kinetic energy. The electrical power generated can be used for various on-board vehicle requirements including plasma flow control around the vehicle or it may be used for augmenting the expanding flow in the high speed nozzle by MHD forces to generate more thrust. In order to achieve this interaction, the air needs to be ionized by an external means even up to fairly high flight speeds, and the leading candidates may be classified as electrical discharge devices. The present kinetic modeling calculations suggest that the use of electron beams with characteristics close to the commercially available e-beam systems (electron energy approx. 60 keV, beam current approx. 0.2 mA/sq cm) to sustain ionization in intermediate pressure, low-temperature (P = 0.1 atm, T = 300 K) supersonic air flows allows considerable reduction of the flow kinetic energy (up to 10 to 20 percent in M = 3 flows). The calculations also suggest that this can be achieved at a reasonable electron beam efficiency (eta approx. 5), even if the e-beam window losses are taken into account. At these conditions, the exit NO and O atom concentrations due to e-beam initiated chemical reactions do not exceed 30 ppm. Increasing the beam current up to approx. 2 mA/sq cm, which corresponds to a maximum electrical conductivity of sigma(sub max) approx. 0.8 mho/m at the loading parameter of K = 0.5, would result in a much greater reduction of the flow kinetic energy (up to 30 to 40 percent). The MHD channel efficiency at these conditions would be greatly reduced (to eta approx. 1) due to increased electron recombination losses in the channel. At these conditions, partial energy conversion from kinetic energy to heat would result in a

  12. Carbon and Noble Gas Isotope Banks in Two-Phase Flow: Changes in Gas Composition During Migration

    NASA Astrophysics Data System (ADS)

    Sathaye, K.; Larson, T.; Hesse, M. A.

    2015-12-01

    In conjunction with the rise of unconventional oil and gas production, there has been a recent rise in interest in noble gas and carbon isotope changes that can occur during the migration of natural gas. Natural gas geochemistry studies use bulk hydrocarbon composition, carbon isotopes, and noble gas isotopes to determine the migration history of gases from source to reservoir, and to trace fugitive gas leaks from reservoirs to shallow groundwater. We present theoretical and experimental work, which helps to explain trends observed in gas composition in various migration scenarios. Noble gases are used as tracers for subsurface fluid flow due to distinct initial compositions in air-saturated water and natural gases. Numerous field studies have observed enrichments and depletions of noble gases after gas-water interaction. A theoretical two-phase gas displacement model shows that differences in noble gas solubility will cause volatile gas components will become enriched at the front of gas plumes, leaving the surrounding residual water stripped of dissolved gases. Changes in hydrocarbon gas composition are controlled by gas solubility in both formation water and residual oil. In addition to model results, we present results from a series of two-phase flow experiments. These results demonstrate the formation of a noble gas isotope banks ahead of a main CO2 gas plume. Additionally, we show that migrating hydrocarbon gas plumes can sweep biogenic methane from groundwater, significantly altering the isotope ratio of the gas itself. Results from multicomponent, two-phase flow experiments qualitatively agree with the theoretical model, and previous field studies. These experimentally verified models for gas composition changes can be used to aid source identification of subsurface gases.

  13. 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).

  14. Synthesis and annealing study of RF sputtered ZnO thin film

    NASA Astrophysics Data System (ADS)

    Singh, Shushant Kumar; Sharma, Himanshu; Singhal, R.; Kumar, V. V. Siva; Avasthi, D. K.

    2016-05-01

    In this paper, we have investigated the annealing effect on optical and structural properties of ZnO thin films, synthesized by RF magnetron sputtering. ZnO thin films were deposited on glass and silicon substrates simultaneously at a substrate temperature of 300 °C using Argon gas in sputtering chamber. Thickness of as deposited ZnO thin film was found to be ~155 nm, calculated by Rutherford backscattering spectroscopy (RBS). These films were annealed at 400 °C and 500 °C temperature in the continuous flow of oxygen gas for 1 hour in tube furnace. X-ray diffraction analysis confirmed the formation of hexagonal wurtzite structure of ZnO thin film along the c-axis (002) orientation. Transmittance of thin films was increased with increasing the annealing temperature estimated by UV-visible transmission spectroscopy. Quality and texture of the thin films were improved with annealing temperature, estimated by Raman spectroscopy.

  15. Comparison of SiOx structure in RF sputtered samples

    NASA Astrophysics Data System (ADS)

    Swart, H. C.; van Hattum, E. D.; Arnoldbik, W. M.; Habraken, F. H. P. M.

    2004-08-01

    The nano-structure of rf magnetron sputtered SiOx films is addressed. More specifically, it was examined whether boundary effects created by the confinement of the material into a thin film induces the formation of a layered structure parallel to the surface during annealing. Different films of SiOx (0 < x < 2) were deposited by an RF magnetron reactive sputtering technique by controlling the relative O2/Ar gas flow during sputter deposition. The graded samples used in this study were 10 nm (x = 2 at the interface to 0 at the surface) and 20 nm (x = 1 to 0), respectively. Samples were annealed in situ from room temperature to 570 °C. Infrared analysis (IR) and X-ray Photoelectron Spectroscopy (XPS) were used to analyze and compare the samples. IR spectra before and after annealing were compared with each other. XPS spectra were drawn during annealing to monitor the changes in the SiOx structure. The sputtered SiOx showed a tendency to decompose into Si and SiO2 during the annealing process. The reaction is characterized by an initial increase in the reaction rate when the temperature was raised, followed by a decrease in the reaction rate toward equilibrium. Two possible models can describe the process. The layer consists of a mixture of all possible sub-oxides with different activation energies for each sub-oxide or the O can segregate from the Si rich region toward an oxygen rich region, where the accumulation of the oxygen forms a diffusion barrier against further diffusion of the oxygen atoms at that specific temperature.

  16. Relation between plasma plume density and gas flow velocity in atmospheric pressure plasma

    SciTech Connect

    Yambe, Kiyoyuki; Taka, Shogo; Ogura, Kazuo

    2014-04-15

    We have studied atmospheric pressure plasma generated using a quartz tube, helium gas, and copper foil electrode by applying RF high voltage. The atmospheric pressure plasma in the form of a bullet is released as a plume into the atmosphere. To study the properties of the plasma plume, the plasma plume current is estimated from the difference in currents on the circuit, and the drift velocity is measured using a photodetector. The relation of the plasma plume density n{sub plu}, which is estimated from the current and the drift velocity, and the gas flow velocity v{sub gas} is examined. It is found that the dependence of the density on the gas flow velocity has relations of n{sub plu} ∝ log(v{sub gas}). However, the plasma plume density in the laminar flow is higher than that in the turbulent flow. Consequently, in the laminar flow, the density increases with increasing the gas flow velocity.

  17. SPUTTERING FROM A POROUS MATERIAL BY PENETRATING IONS

    SciTech Connect

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Caro, A.; Loeffler, M. J.; Farkas, D.

    2011-12-10

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  18. Sputtering from a Porous Material by Penetrating Ions

    NASA Astrophysics Data System (ADS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M. J.; Baragiola, R. A.; Farkas, D.

    2011-12-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  19. GaAs Films Prepared by RF-Magnetron Sputtering

    SciTech Connect

    L.H. Ouyang; D.L. Rode; T. Zulkifli; B. Abraham-Shrauner; N. Lewis; M.R. Freeman

    2001-08-01

    The authors reported on the optical absorption, adhesion, and microstructure of RF-magnetron sputtered films of hydrogenated amorphous and microcrystalline GaAs films for the 1 to 25 {micro}m infrared wavelength rate. Sputtering parameters which were varied include sputtering power, temperature and pressure, and hydrogen sputtering-gas concentration. TEM results show a sharp transition from purely amorphous GaAs to a mixture of microcrystalline GaAs in an amorphous matrix at 34 {+-} 2 C. By optimizing the sputtering parameters, the optical absorption coefficient can be decreased below 100 cm{sup -1} for wavelengths greater than about 1.25 {micro}m. These results represent the lowest reported values of optical absorption for sputtered films of GaAs directly measured by spectrophotometry for the near-infrared wavelength region.

  20. Sputtering from a Porous Material by Penetrating Ions

    NASA Technical Reports Server (NTRS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M.; Baragiola, R. A.; Farkas, D.

    2012-01-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space, Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  1. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix.

    PubMed

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan

    2015-01-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.

  2. Micro/Nano-pore Network Analysis of Gas Flow in Shale Matrix

    PubMed Central

    Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan

    2015-01-01

    The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale pore may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale pore network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed pore network model accounts for the various size distributions and low connectivity of shale pores. The pore size, pore throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted pore network backbone. The numerical results show that apparent permeability is strongly dependent on pore pressure in the reservoir and pore throat size, which is overestimated by low-pressure laboratory tests. With the decrease of reservoir pressure, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-pore network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236

  3. Distribution of Liquid Flow Rates in the Process of Bubbling with Gas Through Gas-Permeable Inserts

    NASA Astrophysics Data System (ADS)

    Gizatulin, R. A.; Valuev, D. V.; Dariev, R. S.; Trifonov, V. A.; Borovikov, I. F.

    2016-08-01

    The authors studied the distribution of the vertical components of the rate in the ascending gas-liquid flow when blowing through the bottom nozzle at two levels under three modes of neutral gas supply. It was estimated that under the intensities of gas (nitrogen) of 2 and 4 L/min-t the type of rates distribution in both cross-sections does not differ from the generally accepted one and practically does not depend upon the intensity of gas supply.

  4. Transport of sputtered particles in capacitive sputter sources

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Mussenbrock, Thomas

    2015-07-01

    The transport of sputtered aluminum inside a multi frequency capacitively coupled plasma chamber is simulated by means of a kinetic test multi-particle approach. A novel consistent set of scattering parameters obtained for a modified variable hard sphere collision model is presented for both argon and aluminum. An angular dependent Thompson energy distribution is fitted to results from Monte Carlo simulations and used for the kinetic simulation of the transport of sputtered aluminum. For the proposed configuration, the transport of sputtered particles is characterized under typical process conditions at a gas pressure of p = 0.5 Pa. It is found that—due to the peculiar geometric conditions—the transport can be understood in a one dimensional picture, governed by the interaction of the imposed and backscattered particle fluxes. It is shown that the precise geometric features play an important role only in proximity to the electrode edges, where the effect of backscattering from the outside chamber volume becomes the governing mechanism.

  5. A fluidic device for measuring constituent masses of a flowing binary gas mixture

    NASA Technical Reports Server (NTRS)

    Prokopius, P. R.

    1973-01-01

    A continuous reading mass flow device was developed to measure the component flow of a binary gas mixture. The basic components of the device are a fluidic humidity sensor and a specially designed flow calorimeter. These components provide readings of gas mixture ratio, mixture heat capacity, heat dissipated by the calorimeter and the gas temperature rise across the calorimeter. These parameter values, applied in the general definitions of specific heat capacity and the heat capacity of a gas mixture, produce calculated component flow rates of the mixture being metered. A test program was conducted to evaluate both the steady state and dynamic performance of the device.

  6. Gas flow induced by ultrasonic cavitation bubble clouds and surface capillary wave.

    PubMed

    Wang, Ying; Li, Tao; Kong, Ling Bing; Hng, Huey Hoon; Lee, Pooi See

    2014-06-01

    In this paper, we report a gas flow phenomenon induced by ultrasonic water cavitation and capillary wave in a vibrating hollow tip and reflector system. The cavitation clouds generated a gas suction force and the capillary wave created tunnels through which the gas could go into the liquid. The gas flow rate was measured and compared under different conditions, including applied power, type of reflector, and tip-to-reflector distance. A model was proposed to explain the mechanisms of the gas flow and analyze the results in the experiments.

  7. Boundary conditions for gas flow problems from anisotropic scattering kernels

    NASA Astrophysics Data System (ADS)

    To, Quy-Dong; Vu, Van-Huyen; Lauriat, Guy; Léonard, Céline

    2015-10-01

    The paper presents an interface model for gas flowing through a channel constituted of anisotropic wall surfaces. Using anisotropic scattering kernels and Chapman Enskog phase density, the boundary conditions (BCs) for velocity, temperature, and discontinuities including velocity slip and temperature jump at the wall are obtained. Two scattering kernels, Dadzie and Méolans (DM) kernel, and generalized anisotropic Cercignani-Lampis (ACL) are examined in the present paper, yielding simple BCs at the wall fluid interface. With these two kernels, we rigorously recover the analytical expression for orientation dependent slip shown in our previous works [Pham et al., Phys. Rev. E 86, 051201 (2012) and To et al., J. Heat Transfer 137, 091002 (2015)] which is in good agreement with molecular dynamics simulation results. More important, our models include both thermal transpiration effect and new equations for the temperature jump. While the same expression depending on the two tangential accommodation coefficients is obtained for slip velocity, the DM and ACL temperature equations are significantly different. The derived BC equations associated with these two kernels are of interest for the gas simulations since they are able to capture the direction dependent slip behavior of anisotropic interfaces.

  8. Development of acoustic flow instruments for solid/gas pipe flows

    SciTech Connect

    Sheen, S.H.; Raptis, A.C.

    1986-05-01

    Two nonintrusive acoustic flow sensing techniques are reported. One technique, passive in nature, simply measures the bandpassed acoustic noise level produced by particle/particle and particle/wall collisions. The noise levels, given in true RMS voltages or in autocorrelations, show a linear relationship to particle velocity but increase with solid concentration. Therefore, the passive technique requires calibration and a separate measure of solid concentration before it can be used to monitor the particle velocity. The second technique is based on the active cross-correlation principle. It measures particle velocity directly by correlating flow-related signatures at two sensing stations. The velocity data obtained by this technique are compared with measurements by a radioactive-particle time-of-flight (TOF) method. A multiplier of 1.53 is required to bring the acoustic data into agreement with the radioactive TOF result. The difference may originate from the difference in flow fields where particles are detected. The radioactive method senses particles mainly in the turbulent region and essentially measures average particle velocity across the pipe, while the acoustic technique detects particles near the pipe wall, and so measures the particle velocity in the viscous sublayer. Both techniques were tested in flows of limestone and air and 1-mm glass beads and air at the Argonne National Laboratory Solid/Gas Test Facility (SGFTF). The test matrix covered solid velocities of 20 to 30 m/s in a 2-in. pipe and solid-to-gas loading ratios of 6 to 22. 37 refs., 19 figs., 4 tabs.

  9. Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

    NASA Technical Reports Server (NTRS)

    Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

    2006-01-01

    The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

  10. A simple model of gas flow in a porous powder compact.

    SciTech Connect

    Shugard, Andrew D.; Robinson, David B.

    2014-04-01

    This report describes a simple model for ideal gas flow from a vessel through a bed of porous material into another vessel. It assumes constant temperature and uniform porosity. Transport is treated as a combination of viscous and molecular flow, with no inertial contribution (low Reynolds number). This model can be used to fit data to obtain permeability values, determine flow rates, understand the relative contributions of viscous and molecular flow, and verify volume calibrations. It draws upon the Dusty Gas Model and other detailed studies of gas flow through porous media.

  11. Nylon-sputtered nanoparticles: fabrication and basic properties

    NASA Astrophysics Data System (ADS)

    Polonskyi, O.; Kylián, O.; Solař, P.; Artemenko, A.; Kousal, J.; Slavínská, D.; Choukourov, A.; Biederman, H.

    2012-12-01

    Nylon-sputtered nanoparticles were prepared using a simple gas aggregation cluster source based on a planar magnetron (Haberland type) and equipped with a nylon target. Plasma polymer particles originated in an aggregation chamber and travelled to a main (deposition) chamber with a gas flow through an orifice. The deposited nanoparticles were observed to have a cauliflower-like structure. The nanoparticles were found to be nitrogen-rich with N/C ratio close to 0.5. An increase in rf power from 60 to 100 W resulted in a decrease in mean particle size from 210 to 168 nm whereas an increase in their residence time in the cluster source from 0.7 to 4.6 s resulted in an increase in the size from 73 to 231 nm.

  12. Sputter Deposition of Metallic Sponges

    SciTech Connect

    Jankowski, A F; Hayes, J P

    2002-01-18

    Metallic films are grown with a sponge-like morphology in the as-deposited condition using planar magnetron sputtering. The morphology of the deposit is characterized by metallic continuity in three dimensions with continuous porosity on the sub-micron scale. The stabilization of the metallic sponge is directly correlated with a limited range for the sputter deposition parameters of working gas pressure and substrate temperature. This sponge-like morphology augments the features as generally understood in the classic zone models of growth for physical vapor deposits. Nickel coatings are deposited with working gas pressures up to 4 Pa and for substrate temperatures up to 1100 K. The morphology of the deposits is examined in plan and in cross-section with scanning electron microscopy. The parametric range of gas pressure and substrate temperature (relative to absolute melt point) for the deposition processing under which the metallic sponges are produced appear universal for many metals, as for example, including gold, silver, and aluminum.

  13. Synthesis and deposition of metal nanoparticles by gas condensation process

    SciTech Connect

    Maicu, Marina Glöß, Daniel; Frach, Peter; Schmittgens, Ralph; Gerlach, Gerald; Hecker, Dominic

    2014-03-15

    In this work, the synthesis of Pt and Ag nanoparticles by means of the inert gas phase condensation of sputtered atomic vapor is presented. The process parameters (power, sputtering time, and gas flow) were varied in order to study the relationship between deposition conditions and properties of the nanoparticles such as their quantity, size, and size distribution. Moreover, the gas phase condensation process can be combined with a plasma enhanced chemical vapor deposition procedure in order to deposit nanocomposite coatings consisting of metallic nanoparticles embedded in a thin film matrix material. Selected examples of application of the generated nanoparticles and nanocomposites are discussed.

  14. Observations of Gas-Liquid Flows Through Contractions in Microgravity

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    1996-01-01

    Tests were conducted for an air-water flow through two sudden contractions aboard the NASA DC-9 low gravity aircraft. Flow rate, residual accelerations, void fraction, film thickness, and pressure drop data were recorded and flow visualization at 250 images per second were recorded. Some preliminary results based on the flow visualization data are presented for bubbly, slug and annular flow.

  15. Sputtering of uranium

    NASA Technical Reports Server (NTRS)

    Gregg, R.; Tombrello, T. A.

    1978-01-01

    Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

  16. Magnetic Field Generation and Zonal Flows in the Gas Giants

    NASA Astrophysics Data System (ADS)

    Duarte, L.; Wicht, J.; Gastine, T.

    2013-12-01

    The surface dynamics of Jupiter and Saturn is dominated by a banded system of fierce zonal winds. The depth of these winds remains unclear but they are thought to be confined to the very outer envelopes where hydrogen remains molecular and the electrical conductivity is negligible. The dynamo responsible for the dipole dominated magnetic fields of both Gas Giants, on the other hand, likely operates in the deeper interior where hydrogen assumes a metallic state. We present numerical simulations that attempt to model both the zonal winds and the interior dynamo action in an integrated approach. Using the anelastic version of the MHD code MagIC, we explore the effects of density stratification and radial electrical conductivity variations. The electrical conductivity is assumed to remain constant in the thicker inner metallic region and decays exponentially towards the outer boundary throughout the molecular envelope. Our results show that the combination of stronger density stratification (Δρ≈55) and a weaker conducting outer layer is essential for reconciling dipole dominated dynamo action and a fierce equatorial zonal jet. Previous simulations with homogeneous electrical conductivity show that both are mutually exclusive, with solutions either having strong zonal winds and multipolar magnetic fields or weak zonal winds and dipole dominated magnetic fields. The particular setup explored here allows the equatorial jet to remain confined to the weaker conducting region where is does not interfere with the deeper seated dynamo action. The equatorial jet can afford to remain geostrophic and reaches throughout the whole shell. This is not an option for the additional mid to higher latitude jets, however. In dipole dominated dynamo solutions, appropriate for the Gas Giants, zonal flows remain very faint in the deeper dynamo region but increase in amplitude in the weakly conducting outer layer in some of our simulations. This suggests that the mid to high latitude jets

  17. 42 CFR 84.94 - Gas flow test; closed-circuit apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Gas flow test; closed-circuit apparatus. 84.94 Section 84.94 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.94 Gas flow...

  18. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Gas flow test; open-circuit apparatus. 84.93 Section 84.93 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES Self-Contained Breathing Apparatus § 84.93 Gas flow...

  19. Dust Particle Growth in a Sputtering Discharge with Krypton

    SciTech Connect

    Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L.

    2011-11-29

    Dust particles are grown in the PKE chamber by sputtering materials. The sputtering efficiency and the gas phase reactions can be affected by the gas type and particularly by the ion mass. Due to the presence of growing dust particles, the huge loss of electrons can trigger many instabilities in the plasma. These instabilities, the growth kinetics and the structure of the dust cloud, are compared by using two different gases: argon and krypton.

  20. Flow Integrating Section for a Gas Turbine Engine in Which Turbine Blades are Cooled by Full Compressor Flow

    SciTech Connect

    Steward, W. Gene

    1999-11-14

    Routing of full compressor flow through hollow turbine blades achieves unusually effective blade cooling and allows a significant increase in turbine inlet gas temperature and, hence, engine efficiency. The invention, ''flow integrating section'' alleviates the turbine dissipation of kinetic energy of air jets leaving the hollow blades as they enter the compressor diffuser.

  1. Formation of dielectric silicon compounds by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Voronov, Yu A.

    2016-09-01

    The paper is devoted to the study of reactive magnetron sputtering of the silicon target in the ambient of inert argon gas with reactive gas, nitrogen or oxygen. The magnetron was powered by two mid-frequency generators of a rectangular pulse of opposite polarity. The negative polarity pulse provides the sputtering of the target. The positive polarity pulse provides removal of accumulated charge from the surface of the target. This method does not require any special devices of resistances matching and provides continuous sputtering of the target.

  2. Visualization of Atomization Gas Flow and Melt Break-up Effects in Response to Nozzle Design

    SciTech Connect

    Anderson, Iver; Rieken, Joel; Meyer, John; Byrd, David; Heidloff, Andy

    2011-04-01

    Both powder particle size control and efficient use of gas flow energy are highly prized goals for gas atomization of metal and alloy powder to minimize off-size powder inventory (or 'reverb') and excessive gas consumption. Recent progress in the design of close-coupled gas atomization nozzles and the water model simulation of melt feed tubes were coupled with previous results from several types of gas flow characterization methods, e.g., aspiration measurements and gas flow visualization, to make progress toward these goals. Size distribution analysis and high speed video recordings of gas atomization reaction synthesis (GARS) experiments on special ferritic stainless steel alloy powders with an Ar+O{sub 2} gas mixture were performed to investigate the operating mechanisms and possible advantages of several melt flow tube modifications with one specific gas atomization nozzle. In this study, close-coupled gas atomization under closed wake gas flow conditions was demonstrated to produce large yields of ultrafine (dia.<20 {mu}m) powders (up to 32%) with moderate standard deviations (1.62 to 1.99). The increased yield of fine powders is consistent with the dual atomization mechanisms of closed wake gas flow patterns in the near-field of the melt orifice. Enhanced size control by stabilized pre-filming of the melt with a slotted trumpet bell pour tube was not clearly demonstrated in the current experiments, perhaps confounded by the influence of the melt oxidation reaction that occurred simultaneously with the atomization process. For this GARS variation of close-coupled gas atomization, it may be best to utilize the straight cylindrical pour tube and closed wake operation of an atomization nozzle with higher gas mass flow to promote the maximum yields of ultrafine powders that are preferred for the oxide dispersion strengthened alloys made from these powders.

  3. Application of the Analogy Between Water Flow with a Free Surface and Two-Dimensional Compressible Gas Flow

    NASA Technical Reports Server (NTRS)

    Orlin, W James; Lindner, Norman J; Butterly, Jack G

    1947-01-01

    The theory of the hydraulic analogy -- that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow -- and the limitations and conditions of the analogy are discussed. A test was run using the hydraulic analogy as applied to the flow about circular cylinders of various diameters at subsonic velocities extending into the supercritical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and air flow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

  4. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-07-07

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  5. Falling microbead counter-flow process for separating gas mixtures

    SciTech Connect

    Hornbostel, Marc D.; Krishnan, Gopala N.; Sanjurjo, Angel

    2015-10-27

    A method and reactor for removing a component from a gas stream is provided. In one embodiment, the method includes providing the gas stream containing the component that is to be removed and adsorbing the component out of the gas stream as the gas stream rises via microbeads of a sorbent falling down an adsorber section of a reactor.

  6. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  7. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  8. The effect of gas diffusion on the flow coefficient for a ventilated cavity

    NASA Technical Reports Server (NTRS)

    Billet, M. L.; Weir, D. S.

    1975-01-01

    The results of an experimental investigation into the effect of gas diffusion on the volume flow-rate of gas needed to sustain a ventilated cavity are presented. Gas diffusion was found to have a significant effect on the ventilated flow rate required to sustain a cavity of a given size. An analysis for the gas diffusion effect was conducted based on a mathematical model of diffusion proposed by Brennen. The results compare favorably with experimental data. Also, an empirical scaling relationship is proposed for ventilated cavity flows.

  9. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  10. Tensorial slip theory for gas flows and comparison with molecular dynamics simulations using an anisotropic gas-wall collision mechanism.

    PubMed

    Pham, Thanh Tung; To, Quy Dong; Lauriat, Guy; Léonard, Céline

    2013-05-01

    In this paper we examine the anisotropic slip theory for gas flows based on tangential accommodation coefficients and compare it with molecular dynamics (MD) results. A special gas-wall boundary condition is employed within MD simulations to mimic the anisotropic gas-wall collision mechanism. Results from MD simulations with different surface orientations show good agreement with the slip quantification proposed in this work.

  11. Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-30

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  12. Analysis of DC gas flow in GM type double inlet pulse tube refrigerators

    NASA Astrophysics Data System (ADS)

    Zhu, Shaowei; Nogawa, Masafumi; Inoue, Tatsuo

    2009-02-01

    In a GM type double inlet pulse tube refrigerator, a DC gas flow is an intrinsic phenomenon. It is important to understand the characteristics of the DC gas flow. In this paper, the relation between the DC gas flow, valve operating time intervals, and flow patterns in the bypass of the GM type double inlet pulse tube refrigerator is studied with a numerical simulation when a symmetric bypass is used. The governing equations of the numerical simulation based on the nodal analysis are discretized with an implicit finite volume method. The simulation result shows that the valve opening angle difference is the main parameter having influence on the DC gas flow, and the effect depends on the flow patterns in the bypass.

  13. Plane Poiseuille flow of a rarefied gas in the presence of strong gravitation.

    PubMed

    Doi, Toshiyuki

    2011-02-01

    Plane Poiseuille flow of a rarefied gas, which flows horizontally in the presence of strong gravitation, is studied based on the Boltzmann equation. Applying the asymptotic analysis for a small variation in the flow direction [Y. Sone, Molecular Gas Dynamics (Birkhäuser, 2007)], the two-dimensional problem is reduced to a one-dimensional problem, as in the case of a Poiseuille flow in the absence of gravitation, and the solution is obtained in a semianalytical form. The reduced one-dimensional problem is solved numerically for a hard sphere molecular gas over a wide range of the gas-rarefaction degree and the gravitational strength. The presence of gravitation reduces the mass flow rate, and the effect of gravitation is significant for large Knudsen numbers. To verify the validity of the asymptotic solution, a two-dimensional problem of a flow through a long channel is directly solved numerically, and the validity of the asymptotic solution is confirmed.

  14. Spinal cord deformation due to nozzle gas flow effects using optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wong, Ronnie J.; Jivraj, Jamil; Vuong, Barry; Ramjist, Joel; Sun, Cuiru; Huang, Yize; Yang, Victor X. D.

    2015-03-01

    The use of gas assistance in laser machining hard materials is well established in manufacturing but not in the context of surgery. Laser cutting of osseous tissue in the context of neurosurgery can benefit from gas-assist but requires an understanding of flow and pressure effects to minimize neural tissue damage. In this study we acquire volumetric flow rates through a gas nozzle on the spinal cord, with dura and without dura.

  15. Effects of Top Layer, Nozzle Arrangement, and Gas Flow Rate on Mixing Time in Agitated Ladles by Bottom Gas Injection

    NASA Astrophysics Data System (ADS)

    Conejo, A. N.; Kitamura, S.; Maruoka, N.; Kim, S.-J.

    2013-08-01

    This research investigates mixing phenomena in bottom gas-stirred ladles using water modeling, which incorporates hexane as the top layer. The effects of slag thickness, nozzle position, number of nozzles, and gas flow rate on mixing time have been investigated. Conditions to improve mixing time have been identified. A single nozzle located at two-thirds of the ladle radius was found to produce the shortest mixing time. Under extremely low gas flow rates, an unusual behavior was observed, where the top layer promoted a decrease in mixing time.

  16. Scaling analysis of gas-liquid two-phase flow pattern in microgravity

    NASA Technical Reports Server (NTRS)

    Lee, Jinho

    1993-01-01

    A scaling analysis of gas-liquid two-phase flow pattern in microgravity, based on the dominant physical mechanism, was carried out with the goal of predicting the gas-liquid two-phase flow regime in a pipe under conditions of microgravity. The results demonstrated the effect of inlet geometry on the flow regime transition. A comparison of the predictions with existing experimental data showed good agreement.

  17. A numerical study of weakly compressible rotating flows in a gas centrifuge

    SciTech Connect

    Harada, I.

    1980-03-01

    Numerical investigations have been made on thermally, mechanically, and thermomechanically driven flows of a weakly compressible gas in a gas centrifuge assuming an axisymmetric continuum flow. The finite difference method developed for these computations is based on the Euler/upwind scheme and provides a numerically stable solution. It is found that an almost cylindrical Couette flow is established in an annulus despite the end effects of the plates and that the two mechanically driven circulations interact with the thermally driven circulations.

  18. {open_quotes}Applications of flow computers for gas measurement and control{close_quotes}

    SciTech Connect

    Douglas, R.

    1995-12-01

    Flow computers, themselves, are undergoing an evolution. One challenge for most vendors will be to offer a low power flow computer whose pricing approaches that of a three variable chart recorder. Many companies in the gas transmission, gas distribution and production industry, expect such a flow computer to be an evolution from today`s smart transmitter technology, because of improved accuracy and innovation of multi-variable transmitters. That is to say, differential pressure, static pressure and temperature all in one transmitter.

  19. An atmospheric pressure flow reactor: Gas phase kinetics and mechanism in tropospheric conditions without wall effects

    NASA Technical Reports Server (NTRS)

    Koontz, Steven L.; Davis, Dennis D.; Hansen, Merrill

    1988-01-01

    A new type of gas phase flow reactor, designed to permit the study of gas phase reactions near 1 atm of pressure, is described. A general solution to the flow/diffusion/reaction equations describing reactor performance under pseudo-first-order kinetic conditions is presented along with a discussion of critical reactor parameters and reactor limitations. The results of numerical simulations of the reactions of ozone with monomethylhydrazine and hydrazine are discussed, and performance data from a prototype flow reactor are presented.

  20. Critical pressure and multiphase flow in Blake Ridge gas hydrates

    USGS Publications Warehouse

    Flemings, P.B.; Liu, Xiuying; Winters, W.J.

    2003-01-01

    We use core porosity, consolidation experiments, pressure core sampler data, and capillary pressure measurements to predict water pressures that are 70% of the lithostatic stress, and gas pressures that equal the lithostatic stress beneath the methane hydrate layer at Ocean Drilling Program Site 997, Blake Ridge, offshore North Carolina. A 29-m-thick interconnected free-gas column is trapped beneath the low-permeability hydrate layer. We propose that lithostatic gas pressure is dilating fractures and gas is migrating through the methane hydrate layer. Overpressured gas and water within methane hydrate reservoirs limit the amount of free gas trapped and may rapidly export methane to the seafloor.

  1. Liquid phase controlled mass transfer in gas-liquid slug flow at low Reynolds numbers

    SciTech Connect

    Elperin, T.; Fominykh, A.

    1995-09-01

    A model of mass transfer during isothermal gas absorption from slugs rising in a channel filled with liquid at small Reynolds numbers is suggested. Fluid flow in the region below the bottom of gas slugs is assumed laminar and therefore vortex rings are not formed at the trailing edge of a gas slug. It is assumed also that a flow of dissolved gas can be described by a point source of mass which is located at the bottom of a gas slug. Intensity of this point source of mass at the bottom of the first gas slug emerging into a pure liquid is equal to the total mass flux from the surface of the first slug. The second gas slug emerges into a liquid with concentration distribution formed by a point source of mass at the bottom of the first gas slug. The third gas slug emerges in a liquid with a concentration distribution formed by a point source of mass at the bottom of the second gas slug and so on. Using this model a recurrent relation for mass flux from the n-th gas slug is derived and the total mass flux from n gas slugs in a gas-liquid slug flow is determined.

  2. Gas/slurry flow in coal liquefaction processes (fluid dynamics in 3-phase flow columns)

    NASA Astrophysics Data System (ADS)

    Ying, D. H. S.; Sivasubramanian, R.; Givens, E. N.

    1981-02-01

    The need for additional data on behavior of three phase systems in large vessels was addressed. Parameters are investigated at conditions that relate directly to the projected demonstration plant operating conditions. Air/water/sand three phase flow system in both a 5 inch diameter and a 12 inch diameter column is used in this cold flow simulation program. The type of distributor used does not seem to affect the solids distribution profiles. The amount of solids retained in the column increases linearly with decreasing slurry velocity while changes in linear gas velocity does not affect the solids distribution profiles for the conditions studied. It is indicated that withdrawing solids from the bottom of the column results in a decreased amount of solids in the column and the solids concentration profile changes accordingly. It is shown that large particles were preferentially removed by virtue of their faster settling rate. The effects of settled particles and particle/particle interaction on solids accumulation were investigated. It it indicated that the presence of large particles does not influence the accumulation or distribution of fine particles. The column enclosure was completed and tested to identify the organic liquid/liquid which is to be used in the 12 inch diameter column.

  3. Intergalactic medium metal enrichment through dust sputtering

    NASA Astrophysics Data System (ADS)

    Bianchi, Simone; Ferrara, Andrea

    2005-04-01

    We study the motion of dust grains into the intergalactic medium (IGM) around redshift z= 3, to test the hypothesis that grains can efficiently pollute the gas with metals through sputtering. We use the results available in the literature for radiation-driven dust ejection from galaxies as initial conditions and follow the motion onwards. Via this mechanism, grains are ejected into the IGM with velocities >100 km s-1 as they move supersonically, grains can be efficiently eroded by non-thermal sputtering. However, Coulomb and collisional drag forces effectively reduce the charged grain velocity. Up-to-date sputtering yields for graphite and silicate (olivine) grains have been derived using the code TRANSPORT OF IONS IN MATTER (TRIM), for which we provide analytic fits. After training our method on a homogeneous density case, we analyse the grain motion and sputtering in the IGM density field as derived from a Λ cold dark matter (CDM) cosmological simulation at z= 3.27. We found that only large (a>~ 0.1μm) grains can travel up to considerable distances (few ×100 kpc physical) before being stopped. Resulting metallicities show a well-defined trend with overdensity δ. The maximum metallicities are reached for 10 < δ < 100[corresponding to systems, in quasi-stellar object (QSO) absorption spectra, with 14.5 < log N(HI) < 16]. However the distribution of sputtered metals is very inhomogeneous, with only a small fraction of the IGM volume polluted by dust sputtering (filling factors of 18 per cent for Si and 6 per cent for C). For the adopted size distribution, grains are never completely destroyed; nevertheless, the extinction and gas photoelectric heating effects resulting from this population of intergalactic grains are well below current detection limits.

  4. Effects of nebulizing and drying gas flow on capillary electrophoresis/mass spectrometry.

    PubMed

    Huikko, Katri; Kotiaho, Tapio; Kostiainen, Risto

    2002-01-01

    This study was focused on examining the influence of gas flow parameters on capillary electrophoresis/mass spectrometry (CE /MS) performance using sheath-liquid CE /MS interfaces. The effects of nebulizing and drying gas velocity and drying gas temperature on CE separation and MS detection sensitivity were systematically determined. Nebulizing gas velocity was observed to be a critical parameter in the optimization of CE /MS method, since it affected both MS detection sensitivity, and also CE separation efficiency for one interface design tested. Better detection sensitivity was obtained when the nebulizing gas velocity was increased. However, high velocity of the nebulizing gas flow can cause a hydrodynamic bulk flow inside the CE capillary, thus clearly increasing the apparent mobility and decreasing the resolution obtained for the compounds studied. Increasing the drying gas velocity or temperature did not affect the apparent mobility or the separation efficiency and the temperature could be increased to achieve the optimal detection sensitivity in the CE /MS analysis. For comparison, the effects of nebulizing gas flow were studied using a different design of the coaxial sheath-liquid CE /MS interface, and in this case better detection sensitivity but no effect on CE separation efficiency was observed with increased nebulizing gas velocity. These different effects of nebulizing gas flow on the CE bulk flow were concluded to result from pressure differences at the tip of the CE capillaries for the different CE /MS interface arrangements. It is therefore recommended that the cross-sectional dimensions of the fused-silica and steel capillaries, and the gas streamlines, should be optimized when CE /MS interfaces are built. Moreover, the effect of gas flow on CE separation should be studied when optimizing the CE /MS operation parameters.

  5. Experimental perfect-gas study of expansion-tube flow characteristics

    NASA Technical Reports Server (NTRS)

    Shinn, J. L.; Miller, C. G., III

    1978-01-01

    Results of an experimental investigation of expansion tube flow characteristics performed with helium test gas and acceleration gas are presented. The use of helium, eliminates complex real gas chemistry in the comparison of measured and predicted flow quantities. The driver gas was unheated helium at a nominal pressure of 33 MN sq m. The quiescent test gas pressure and quiescent acceleration gas pressure were varied from 0.7 to 50 kN/sq m and from 2.5 to 53 N/sq m, respectively. The effects of tube-wall boundary layer growth and finite secondary diaphragm opening time were examined through the variation of the quiescent gas pressures and secondary diaphragm thickness. Optimum operating conditions for helium test gas were also defined.

  6. Experimental investigation of the gas flow in gas-assisted laser cutting by means of geometrically similar models

    NASA Astrophysics Data System (ADS)

    Makashev, N. K.; Buzykin, O. G.; Asmolov, E. S.

    1996-03-01

    The gas flow in the system of nozzle-cut is investigated for the case of gas-assisted laser cutting of materials. The direct measurement of pressure fields is used with geometrically similar models which simulate the configuration forming during the laser cutting of metal sheet. The effect of geometric parameters of the system on the flow pattern in the kerf and on its features responsible for the cutting quality is analyzed. The choice and proper implementation of the assisting gas blowing to the cut front zone if of great importance for the gas-assisted laser cutting. There exist many various methods and facilities for the gas delivery. Nozzle configurations of many kinds and the peculiarities of free jet streams formed by them was the subject of extensive exploration. The efficiency of the nozzle under investigation was evaluated empirically or by the pressure exerted to the flat plate in the stagnation point of normally impinging jet. Recently the attention of investigators has been redirected to the details of the gas flow in the cut kerf. This activity is connected with the development of the theoretical models of gas-assisted laser cutting which serves to appreciate the role of the gas flow parameters in the phenomena responsible for the cutting efficiency. The efficiency of the gas delivery which is characterized by the cutting speed, the maximum thickness of the cut material, or the quality parameters of cut edges depends mainly on the flow features in the cut kerf. In the present paper these features are discussed closely. The results of the investigation provide the ability to choose purposefully the geometrical parameters of the nozzle facilities for laser cutter.

  7. Stoichiometry control of magnetron sputtered Bi 2Sr 2Ca 1- xY xCu 2O y (0 ⩽ x ⩽ 0.5) thin film, composition spread libraries: Substrate bias and gas density factors

    NASA Astrophysics Data System (ADS)

    Sanderson, R. J.; Hewitt, K. C.

    2005-09-01

    A magnetron sputtering method for the production of thin-film libraries with a spatially varying composition, x, in Bi 2Sr 2Ca 1- xY xCu 2O y (0 ⩽ x ⩽ 0.5) has been developed. Two targets with a composition of Bi 2Sr 2YCu 2O 8.5+ δ and Bi 2Sr 2CaCu 2O 8+ δ are co-sputtered with appropriate masks. The target masks produce a linear variation in opposite, but co-linear radial direction, and the rotation speed of the substrate table is sufficient to intimately mix the atoms. EDS/WDS composition studies of the films show a depletion of Sr and Bi that is due to oxygen anion resputtering. The depletion is most pronounced at the centre of the film (i.e. on-axis with the target) and falls off symmetrically to either side of the 75 mm substrate. At either edge of the film the stoichiometry matches the desired ratios. Using a 12 mTorr process gas of argon and oxygen in a 2:1 ratio, the strontium depletion is corrected. The bismuth depletion is eliminated by employing a rotating carbon brush apparatus which supplies a -20 V DC bias to the sample substrate. The negative substrate bias has been used successfully with an increased chamber pressure to eliminate the resputtering effect across the film. The result is a thin film composition spread library with the desired stoichiometry.

  8. Conductive conformal thin film coatings for textured PV: ALD versus sputtering

    NASA Astrophysics Data System (ADS)

    Dameron, Arrelaine; Christensen, Steven; Galante, Marie; Berry, Joseph; Gillaspie, Dane; Perkins, John; Ginley, David; Gennett, Thomas

    2011-09-01

    Next-generation photovoltaic structures require well-established deposition routes to conformal and conducting materials with defined chemical, physical and electronic composition. This work reports on the preliminary findings associated with conformal metal oxides on structured substrates including: 1) Discovery of sputtering process conditions that can be made semi-conformal when combined with in-situ techniques such as ion-beam milling for honing surface structures; 2) Development of relevant ALD chemistries that are materials-properties competitive with sputtered materials; 3) Evaluation of chemically-functionalized surface structures that maximize surface area but are structurally tailored for efficient gas flow and to minimize line-of-sight shadowing. The initial experiments have centered on combinations of amorphous and crystalline indium oxide, zinc oxide, aluminum zinc oxide, indium tin oxide, fluorinated tin oxide and indium zinc oxide. This presentation will describe these initial experiments and elucidate key physiochemical nature of the deposited thin films.

  9. Monte Carlo simulations of nanoscale focused neon ion beam sputtering.

    PubMed

    Timilsina, Rajendra; Rack, Philip D

    2013-12-13

    A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed.

  10. Iran seeking help in regaining prerevolution oil and gas flow

    SciTech Connect

    Tippee, B.

    1996-02-19

    This paper reviews the goals of the Iranian oil and gas industry to rebuild their oil and gas production facilities by using foreign investment. It discusses the historical consequences of war in the region to diminish the production and postpone the recovery of natural gas which is currently flared. It describes the major projects Iran hopes to develop through international partnerships and includes field development, pipeline construction, gas reinjection, gas treatment facilities, and new offshore operation. The paper also reviews the US policy on Iran and its attempt to apply sanctions towards this country.

  11. Application of the Analogy Between Water Flow with a Free Surface and Two-dimensional Compressible Gas Flow

    NASA Technical Reports Server (NTRS)

    Orlin, W James; Lindner, Norman J; Bitterly, Jack G

    1947-01-01

    The theory of hydraulic analogy, that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow and the limitations and conditions of the analogy are discussed. A test run was made using the hydraulic analogy as applied to the flow about circular cylinders at various diameters at subsonic velocities extending to the super critical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and airflow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.

  12. Fuel flow regulator control for a diesel engine with exhaust gas driven turbocharger

    SciTech Connect

    Ludwig, G.C.

    1984-03-06

    A fuel flow regulator for an internal combustion engine having an exhaust gas turbocharger is disclosed. The fuel flow regulator responds to intake manifold pressure. Thus the fuel flow regulator increases the maximum fuel flow to the internal combustion engine from a first maximum predetermined fuel flow rate when the intake manifold pressure is at a first predetermined intake air pressure level to a second predetermined maximum fuel flow rate when the intake air manifold pressure is at a second predetermined intake air pressure level. Additionally, the fuel flow regulator decreases fuel flow to a third maximum fuel flow rate which is less than the first predetermined maximum fuel flow rate when the intake manifold pressure is greater than the second predetermined intake air pressure level. Therefore, the fuel flow regulator protects the internal combustion engine from overboost of the engine by the turbocharger and for overfueling the engine.

  13. Experimental on two sensors combination used in horizontal pipe gas-water two-phase flow

    SciTech Connect

    Wu, Hao; Dong, Feng

    2014-04-11

    Gas-water two phase flow phenomenon widely exists in production and living and the measurement of it is meaningful. A new type of long-waist cone flow sensor has been designed to measure two-phase mass flow rate. Six rings structure of conductance probe is used to measure volume fraction and axial velocity. The calibration of them have been made. Two sensors have been combined in horizontal pipeline experiment to measure two-phase flow mass flow rate. Several model of gas-water two-phase flow has been discussed. The calculation errors of total mass flow rate measurement is less than 5% based on the revised homogeneous flow model.

  14. Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities.

    PubMed

    Sharma, Prabhakar; Poulsen, Tjalfe G

    2010-07-01

    Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning. These two materials were selected to have approximately the same particle shape. Column gas transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different gas flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile gas phases. The results showed that gas dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. Gas dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile gas content in both materials increased with increasing gas flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile gas compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity. PMID:20681430

  15. Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities.

    PubMed

    Sharma, Prabhakar; Poulsen, Tjalfe G

    2010-07-01

    Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning. These two materials were selected to have approximately the same particle shape. Column gas transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different gas flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile gas phases. The results showed that gas dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. Gas dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile gas content in both materials increased with increasing gas flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile gas compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity.

  16. Low-damage high-throughput grazing-angle sputter deposition on graphene

    SciTech Connect

    Chen, C.-T.; Gajek, M.; Raoux, S.; Casu, E. A.

    2013-07-15

    Despite the prevalence of sputter deposition in the microelectronics industry, it has seen very limited applications for graphene electronics. In this letter, we report systematic investigation of the sputtering induced damages in graphene and identify the energetic sputtering gas neutrals as the primary cause of graphene disorder. We further demonstrate a grazing-incidence sputtering configuration that strongly suppresses fast neutral bombardment and retains graphene structure integrity, creating considerably lower damage than electron-beam evaporation. Such sputtering technique yields fully covered, smooth thin dielectric films, highlighting its potential for contact metals, gate oxides, and tunnel barriers fabrication in graphene device applications.

  17. Direct numerical simulation of interfacial wave generation in turbulent gas-liquid flows in horizontal channels

    NASA Astrophysics Data System (ADS)

    Campbell, Bryce; Hendrickson, Kelli; Liu, Yuming; Subramani, Hariprasad

    2014-11-01

    For gas-liquid flows through pipes and channels, a flow regime (referred to as slug flow) may occur when waves form at the interface of a stratified flow and grow until they bridge the pipe diameter trapping large elongated gas bubbles within the liquid. Slug formation is often accompanied by strong nonlinear wave-wave interactions, wave breaking, and gas entrainment. This work numerically investigates the fully nonlinear interfacial evolution of a two-phase density/viscosity stratified flow through a horizontal channel. A Navier-Stokes flow solver coupled with a conservative volume-of-fluid algorithm is use to carry out high resolution three-dimensional simulations of a turbulent gas flowing over laminar (or turbulent) liquid layers. The analysis of such flows over a range of gas and liquid Reynolds numbers permits the characterization of the interfacial stresses and turbulent flow statistics allowing for the development of physics-based models that approximate the coupled interfacial-turbulent interactions and supplement the heuristic models built into existing industrial slug simulators.

  18. Nonstationary Gas Flow in Thin Pipes of Variable Cross Section

    NASA Technical Reports Server (NTRS)

    Guderley, G.

    1948-01-01

    Characteristic methods for nonstationary flows have been published only for the special case of the isentropic flow up until the present, althought they are applicable in various places to more difficult questions too. This report derives the characteristic method for the flows which depend only on the position coordinates and time. At the same time the treatment of compression shocks is shown.

  19. Modeling of dilute two-phase multispecies solid/gas flows

    SciTech Connect

    Doss, E.D.; Srinivasan, M.G.; Raptis, A.C.

    1986-06-01

    The report gives a detailed description of the analytical modeling that underlies the numerical code for predicting the flow of dilute solid/gas flows in pipes. The model is two-phase multispecies. Particles of one size are treated as one species and the equations of particle dynamics include terms to account for momentum transfer between species and the wall friction on each species of particles. New expressions for particle/particle interaction and wall friction for multispecies flow are derived. Results of parametric studies based on the new expressions are described. The predictions of this model for gas/powder flow through a venturi are compared with experimental measurements. The model's capability for predicting the flow in Argonne's Solid/Gas Flow Test Facility will be the subject of a companion report. 26 refs., 16 figs.

  20. Gas-kinetic unified algorithm for hypersonic flows covering various flow regimes solving Boltzmann model equation in nonequilibrium effect

    SciTech Connect

    Li, Zhihui; Ma, Qiang; Wu, Junlin; Jiang, Xinyu; Zhang, Hanxin

    2014-12-09

    Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinate points and numerical quadrature rules for macroscopic flow variables with dynamic updating evolvement are developed to simulate hypersonic flows, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of flow regimes. The hypersonic flows involving non-equilibrium effect are numerically simulated including the inner flows of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp flow with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering flows around tine double-cone body.

  1. Gas-kinetic unified algorithm for hypersonic flows covering various flow regimes solving Boltzmann model equation in nonequilibrium effect

    NASA Astrophysics Data System (ADS)

    Li, Zhihui; Wu, Junlin; Ma, Qiang; Jiang, Xinyu; Zhang, Hanxin

    2014-12-01

    Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinate points and numerical quadrature rules for macroscopic flow variables with dynamic updating evolvement are developed to simulate hypersonic flows, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of flow regimes. The hypersonic flows involving non-equilibrium effect are numerically simulated including the inner flows of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp flow with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering flows around tine double-cone body.

  2. Study of gas-liquid flow in model porous media for heterogeneous catalysis

    NASA Astrophysics Data System (ADS)

    Francois, Marie; Bodiguel, Hugues; Guillot, Pierre; Laboratory of the Future Team

    2015-11-01

    Heterogeneous catalysis of chemical reactions involving a gas and a liquid phase is usually achieved in fixed bed reactors. Four hydrodynamic regimes have been observed. They depend on the total flow rate and the ratio between liquid and gas flow rate. Flow properties in these regimes influence transfer rates. Rather few attempts to access local characterization have been proposed yet, though these seem to be necessary to better describe the physical mechanisms involved. In this work, we propose to mimic slices of reactor by using two-dimensional porous media. We have developed a two-dimensional system that is transparent to allow the direct observation of the flow and the phase distribution. While varying the total flow rate and the gas/liquid flow rate ratio, we observe two hydrodynamic regimes: at low flow rate, the gaseous phase is continuous (trickle flow), while it is discontinuous at higher flow rate (pulsed flow). Thanks to some image analysis techniques, we are able to quantify the local apparent liquid saturation in the system. Its fluctuations in time are characteristic of the transition between the two regimes: at low liquid flow rates, they are negligible since the liquid/gas interface is fixed, whereas at higher flow rates we observe an alternation between liquid and gas. This transition between trickle to pulsed flow is in relative good agreement with the existing state of art. However, we report in the pulsed regime important flow heterogeneities at the scale of a few pores. These heterogeneities are likely to have a strong influence on mass transfers. We acknowledge the support of Solvay.

  3. Ion transport membrane module and vessel system with directed internal gas flow

    SciTech Connect

    Holmes, Michael Jerome; Ohrn, Theodore R.; Chen, Christopher Ming-Poh

    2010-02-09

    An ion transport membrane system comprising (a) a pressure vessel having an interior, an inlet adapted to introduce gas into the interior of the vessel, an outlet adapted to withdraw gas from the interior of the vessel, and an axis; (b) a plurality of planar ion transport membrane modules disposed in the interior of the pressure vessel and arranged in series, each membrane module comprising mixed metal oxide ceramic material and having an interior region and an exterior region; and (c) one or more gas flow control partitions disposed in the interior of the pressure vessel and adapted to change a direction of gas flow within the vessel.

  4. Properties of p-type N-doped Cu2O thin films prepared by reactive sputtering

    NASA Astrophysics Data System (ADS)

    Jung, Yu Sup; Choi, Hyung Wook; Kim, Kyung Hwan

    2014-11-01

    We have investigated the electrical, optical, and structural properties of p-type nitrogen (N)-doped Cu2O thin films prepared at various nitrogen gas flow rates for application in heterojunction solar cells. The N-doped Cu2O thin films were fabricated by facing-target reactive sputtering. The hole concentration of the N-doped Cu2O thin films was affected by N2 gas flow rate. With increasing N2 gas flow rate from 0 to 0.5 sccm, the hole concentration and mobility of N-doped Cu2O films increased sharply. The resistivity, hole concentration, and mobility of the N-doped Cu2O films prepared at a N2 gas flow rate of 4 sccm were 1.9 Ω·cm, 2.0 × 1018 cm-3, and 3.4 cm2·V-1·s-1, respectively. The N-doped Cu2O films showed Cu2O(111) and Cu2O(200) diffraction peaks. Cu2O(200) diffraction peak intensity increased slightly with N2 gas flow rate. The Cu2O(200) peaks were stronger at a N2 gas flow rate of 4 sccm than at other gas flow rates.

  5. Effects of Gravity on Cocurrent Two-Phase Gas-Liquid Flows Through Packed Columns

    NASA Technical Reports Server (NTRS)

    Motil, Brian J.; Balakotaiah, Vemuri; Kamotani, Yasuhiro

    2001-01-01

    This work presents the experimental results of research on the influence of gravity on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid two-phase flow through packed columns. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under reduced gravity conditions compared to normal gravity cocurrent down-flow. This is illustrated by comparing the flow regime transitions found in reduced gravity with the transitions predicted by Talmor. Next, the effect of gravity on the total pressure drop in a packed column is shown to depend on the flow regime. The difference is roughly equivalent to the liquid static head for bubbly flow but begins to decrease at the onset of pulse flow. As the spray flow regime is approached by increasing the gas to liquid ratio, the effect of gravity on pressure drop becomes negligible. Finally, gravity tends to suppress the amplitude of each pressure pulse. An example of this phenomenon is presented.

  6. Properties of a-C:H:Si thin films deposited by middle-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jiang, Jinlong; Wang, Yubao; Du, Jinfang; Yang, Hua; Hao, Junying

    2016-08-01

    The silicon doped hydrogenated amorphous carbon (a-C:H:Si) films were prepared on silicon substrates by middle-frequency magnetron sputtering silicon target in an argon and methane gas mixture atmosphere. The deposition rate, chemical composition, structure, surface properties, stress, hardness and tribological properties in the ambient air of the films were systemically investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), nanoindentation and tribological tester. The results show that doped silicon content in the films is controlled in the wide range from 39.7 at.% to 0.2 at.% by various methane gas flow rate, and methane flow rate affects not only the silicon content but also its chemical bonding structure in the films due to the transformation of sputtering modes. Meanwhile, the sp3 carbon component in the films linearly increases with increasing of methane flow rate. The film deposited at moderate methane flow rate of 40-60 sccm exhibits the very smooth surface (RMS roughness 0.4 nm), low stress (0.42 GPa), high hardness (21.1 GPa), as well as low friction coefficient (0.038) and wear rate (1.6 × 10-7 mm3/Nm). The superior tribological performance of the films could be attributed to the formation and integral covering of the transfer materials on the sliding surface and their high hardness.

  7. A Coupled Plasma Dynamics and Gas Flow Model for Semiconductor Processing

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1998-01-01

    A continuum modeling approach by self-consistently coupling plasma dynamics and gas flow will be presented for the analysis of high density plasma reactors. Experimental data shows that gas flow distribution affects the etch rate uniformity even at low pressures (6-20 mTorr) and flow rates (20-70 sccm). This study will investigate the effects of gas flow and gas energy on bulk plasma densities and temperatures using a continuum model. The model solves multidimensional equations of mass balance for neutrals and ions, gas momentum, separate energy equations for electrons and neutrals and Maxwell's equations for power coupling. A test case of N2 plasma in a 300mm TCP etch reactor, for which hybrid model and Langmuir probe data are available, is chosen for this analysis. Our preliminary results show that modeling gas flow and energy improves the predictions of electron density and its spatial variation in the reactor when compared with the experimental data. The aim of this study is to identify the operating conditions for the TCP reactor when a self-consistent modeling of gas flow is important.

  8. Gas-lift pumps for flowing and purifying molten silicon

    DOEpatents

    Kellerman, Peter L.; Carlson, Frederick

    2016-02-23

    The embodiments herein relate to a sheet production apparatus. A vessel is configured to hold a melt of a material and a cooling plate is disposed proximate the melt. This cooling plate configured to form a sheet of the material on the melt. A pump is used. In one instance, this pump includes a gas source and a conduit in fluid communication with the gas source. In another instance, this pump injects a gas into a melt. The gas can raise the melt or provide momentum to the melt.

  9. Model of Gas Flow Through Porous Refractory Applied to an Upper Tundish Nozzle

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Thomas, Brian G.

    2015-02-01

    Argon gas commonly is injected into the liquid metal stream through the porous refractory walls in many metallurgical processes. In this work, a new model has been developed to investigate gas diffusion through heated porous refractory, including the effects of refractory geometry, the thermal expansion of the gas, temperature-dependent gas viscosity, and possible leakage into unsealed joints. A novel one-way-flow pressure boundary condition has been formulated and implemented to prevent unrealistic flow into the refractory. The complete model is validated with both analytical solutions of 1D test problems and observations of a water bubbling experiment. Then, to demonstrate practical application of this general model, argon gas flow is simulated through a double-slitted upper tundish nozzle during continuous steel casting with a slide-gate system. Realistic liquid steel pressure distributions with the bubbling threshold condition are applied on the inner surface. Parametric studies are conducted to investigate the effects of joint gas leakage, refractory conductivity, permeability, and injection pressure on the resulting gas distributions, gas mass flow rates, and leakage fraction. This new model of porous flow can serve as the first step of a comprehensive multiphase model system.

  10. Characterization of annular two-phase gas-liquid flows in microgravity

    NASA Technical Reports Server (NTRS)

    Bousman, W. Scott; Mcquillen, John B.

    1994-01-01

    A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

  11. Analytical Solution for Subsurface Gas Flow to a Well Induced by Surface Pressure Fluctuations

    SciTech Connect

    Rossabi, J.

    2001-06-20

    A simple analytical model is presented for predicting subsurface gas flow to a vadose zone well in response to atmospheric pressure fluctuations (barometric pumping). The effective radial permeability (kr) in the vicinity of the well is determined during model calibration using less than two weeks of data. By combining the flow solution with a solution for the vertical gas pressure, only atmospheric pressure data are required to predict the induced flow through a well. The ability to quantitatively predict naturally induced flow in vadose zone wells by simple and inexpensive measurements is invaluable for systems using barometric pumping for remediation.

  12. Influence of the gas-flow Reynolds number on a plasma column in a glass tube

    SciTech Connect

    Jin, Dong Jun; Uhm, Han S.; Cho, Guangsup

    2013-08-15

    Atmospheric-plasma generation inside a glass tube is influenced by gas stream behavior as described by the Reynolds number (Rn). In experiments with He, Ne, and Ar, the plasma column length increases with an increase in the gas flow rate under laminar flow characterized by Rn < 2000. The length of the plasma column decreases as the flow rate increases in the transition region of 2000 < Rn < 4000. For a turbulent flow beyond Rn > 4000, the length of the plasma column is short in front of the electrode, eventually leading to a shutdown.

  13. Gas flow across a wet screen - Analogy to a relief valve with hysteresis

    NASA Technical Reports Server (NTRS)

    Nachman, A.; Dodge, F. T.

    1983-01-01

    The flow of gas through a wet fine-mesh screen is analyzed in terms of the capillary forces of the liquid wetting the screen and the pressure difference across the screen thickness driving the gas flow. Several different types of time-dependent flow are shown to be possible. The most interesting type is one in which the pressure difference opens small channels in the liquid, which are then closed rapidly by the wetting action of the liquid. The opening and closing exhibit hysteresis, and the flow is highly oscillatory.

  14. Analytical solution for subsurface gas flow to a well induced by surface pressure fluctuations.

    PubMed

    Rossabi, Joseph; Falta, Ronald W

    2002-01-01

    A simple analytical model is presented for predicting subsurface gas flow to a vadose-zone well in response to atmospheric pressure fluctuations (barometric pumping). The effective radial permeability (kr) in the vicinity of the well is determined during model calibration using less than two weeks worth of data. By combining the flow solution with a solution for the vertical gas pressure, only atmospheric pressure data are required to predict the induced flow through a well. The ability to quantitatively predict naturally induced flow in vadose-zone wells by simple and inexpensive measurements is invaluable for systems using barometric pumping for remediation. PMID:11798048

  15. Dynamic gas slippage: a unique dual-mechanism approach to the flow of gas in tight formations

    SciTech Connect

    Ertekin, T.; King, G.R.; Schwerer, F.C.

    1983-01-01

    A mathematical formulation, applicable to both numeric simulation and transient well analysis, describing the flow of gas in very tight porous media has been developed. Unique to this formulation is the dual- mechanism transport of gas. In this formulation, gas is assumed to be traveling under the influence of 2 fields: a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's Law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's Law (inertial-turbulent effects are ignored). The combination of these 2 flow mechanisms rigorously yields a composition, pressure, and saturation dependent slippage factor. 21 references.

  16. Control of composition and crystallinity in hydroxyapatite films deposited by electron cyclotron resonance plasma sputtering

    NASA Astrophysics Data System (ADS)

    Akazawa, Housei; Ueno, Yuko

    2014-01-01

    Hydroxyapatite (HAp) films were deposited by electron cyclotron resonance plasma sputtering under a simultaneous flow of H2O vapor gas. Crystallization during sputter-deposition at elevated temperatures and solid-phase crystallization of amorphous films were compared in terms of film properties. When HAp films were deposited with Ar sputtering gas at temperatures above 460 °C, CaO byproducts precipitated with HAp crystallites. Using Xe instead of Ar resolved the compositional problem, yielding a single HAp phase. Preferentially c-axis-oriented HAp films were obtained at substrate temperatures between 460 and 500 °C and H2O pressures higher than 1×10-2 Pa. The absorption signal of the asymmetric stretching mode of the PO43- unit (ν3) in the Fourier-transform infrared absorption (FT-IR) spectra was the narrowest for films as-crystallized during deposition with Xe, but widest for solid-phase crystallized films. While the symmetric stretching mode of PO43- (ν1) is theoretically IR-inactive, this signal emerged in the FT-IR spectra of solid-phase crystallized films, but was absent for as-crystallized films, indicating superior crystallinity for the latter. The Raman scattering signal corresponding to ν1 PO43- sensitively reflected this crystallinity. The surface hardness of as-crystallized films evaluated by a pencil hardness test was higher than that of solid-phase crystallized films.

  17. Method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors

    NASA Technical Reports Server (NTRS)

    Nalim, M. Razi (Inventor); Paxson, Daniel E. (Inventor)

    1999-01-01

    A method and apparatus for cold gas reinjection in through-flow and reverse-flow wave rotors having a plurality of channels formed around a periphery thereof. A first port injects a supply of cool air into the channels. A second port allows the supply of cool air to exit the channels and flow to a combustor. A third port injects a supply of hot gas from the combustor into the channels. A fourth port allows the supply of hot gas to exit the channels and flow to a turbine. A diverting port and a reinjection port are connected to the second and third ports, respectively. The diverting port diverts a portion of the cool air exiting through the second port as reinjection air. The diverting port is fluidly connected to the reinjection port which reinjects the reinjection air back into the channels. The reinjection air evacuates the channels of the hot gas resident therein and cools the channel walls, a pair of end walls of the rotor, ducts communicating with the rotor and subsequent downstream components. In a second embodiment, the second port receives all of the cool air exiting the channels and the diverting port diverts a portion of the cool air just prior to the cool air flowing to the combustor.

  18. Real-gas effects 1: Simulation of ideal gas flow by cryogenic nitrogen and other selected gases

    NASA Technical Reports Server (NTRS)

    Hall, R. M.

    1980-01-01

    The thermodynamic properties of nitrogen gas do not thermodynamically approximate an ideal, diatomic gas at cryogenic temperatures. Choice of a suitable equation of state to model its behavior is discussed and the equation of Beattie and Bridgeman is selected as best meeting the needs for cryogenic wind tunnel use. The real gas behavior of nitrogen gas is compared to an ideal, diatomic gas for the following flow processes: isentropic expansion; normal shocks; boundary layers; and shock wave boundary layer interactions. The only differences in predicted pressure ratio between nitrogen and an ideal gas that may limit the minimum operating temperatures of transonic cryogenic wind tunnels seem to occur at total pressures approaching 9atmospheres and total temperatures 10 K below the corresponding saturation temperature, where the differences approach 1 percent for both isentropic expansions and normal shocks. Several alternative cryogenic test gases - air, helium, and hydrogen - are also analyzed. Differences in air from an ideal, diatomic gas are similar in magnitude to those of nitrogen. Differences for helium and hydrogen are over an order of magnitude greater than those for nitrogen or air. Helium and hydrogen do not approximate the compressible flow of an ideal, diatomic gas.

  19. Discharge Physics of High Power Impulse Magnetron Sputtering

    SciTech Connect

    Anders, Andre

    2010-10-13

    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  20. Application of the methods of gas dynamics to water flows with free surface I : flows with no energy dissipation

    NASA Technical Reports Server (NTRS)

    Preiswerk, Ernst

    1940-01-01

    The application is treated in sufficient detail to facilitate as much as possible its application by the engineer who is less familiar with the subject. The present work was undertaken with two objects in view. In the first place, it is considered as a contribution to the water analogy of gas flows, and secondly, a large portion is devoted to the general theory of the two-dimensional supersonic flows.

  1. Radially-Inflowing Molecular Gas Deposited by a X-ray Cooling Flow

    NASA Astrophysics Data System (ADS)

    Lim, Jeremy; Ao, Y.; Dinh, V.

    2006-12-01

    Galaxy clusters are immersed in hot X-ray-emitting gas that constitutes a large fraction of their baryonic mass. Radiative cooling of this gas, if not adequately balanced by heat input, should result in an inflow of cooler gas to the central dominant giant elliptical (cD) galaxy. Although a straightforward prediction made nearly twenty years ago, the occurrence of such X-ray cooling flows is widely questioned as gas at lower temperatures is often not found at the predicted quantities. The exceptions are cD galaxies harbouring large quantities of cool molecular gas, but the origin of this gas is uncertain as ram-pressure stripping or cannibalism of gas-rich cluster galaxies provide viable alternatives to cooling flows. Here, we present the most direct evidence yet for the deposition of molecular gas in a cD galaxy, Perseus A, from a X-ray cooling flow. The molecular gas detected in this galaxy is concentrated in three radial filaments with projected lengths of at least 2 kpc, one extending inwards close to the active nucleus and the other two extending outwards to at least 8 kpc on the east and west. All three filaments coincide with bright Hα features, and lie along a central X-ray ridge where any cooling flow is strongest. The two outer filaments exhibit increasingly blueshifted velocities at smaller radii that we show trace radial inflow along the gravitational potential of the galaxy. The innermost filament appears to be settling into the potential well, and may fuel the central supermassive black hole whose radio jets heat gas over a large solid angle in the north-south direction. Our results demonstrate that X-ray cooling flows can indeed deposit large quantities of cool gas, but only intermittently along directions where the X-ray gas is not being reheated.

  2. Gas flow stabilized megavolt spark gap for repetitive pulses

    DOEpatents

    Lawson, R.N.; O'Malley, M.W.; Rohwein, G.J.

    A high voltage spark gap switch is disclosed including a housing having first and second end walls being spaced apart by a predetermined distance. A first electrode is positioned on the first end wall and a second electrode is positioned on the second end wall. The first and second electrodes are operatively disposed relative to each other and are spaced apart by a predetermined gap. An inlet conduit is provided for supplying gas to the first electrode. The conduit includes a nozzle for dispersing the gas in the shape of an annular jet. The gas is supplied into the housing at a predetermined velocity. A venturi housing is disposed within the second electrode. An exhaust conduit is provided for discharging gas and residue from the housing. The gas supplied at the predetermined velocity to the housing through the inlet conduit and the nozzle in an annular shape traverses the gap between the first and second electrodes and entrains low velocity gas within the housing decreasing the velocity of the gas supplied to the housing and increasing the diameter of the annular shape. The venturi disposed within the second electrode recirculates a large volume of gas to clean and cool the surface of the electrodes.

  3. Gas flow stabilized megavolt spark gap for repetitive pulses

    DOEpatents

    Lawson, Robert N.; O'Malley, Martin W.; Rohwein, Gerald J.

    1986-01-01

    A high voltage spark gap switch including a housing having first and second end walls being spaced apart by a predetermined distance. A first electrode is positioned on the first end wall and a second electrode is positioned on the second end wall. The first and second electrodes are operatively disposed relative to each other and are spaced apart by a predetermined gap. An inlet conduit is provided for supplying gas to the first electrode. The conduit includes a nozzle for dispersing the gas in the shape of an annular jet. The gas is supplied into the housing at a predetermined velocity. A venturi housing is disposed within the second electrode. An exhaust conduit is provided for discharging gas and residue from the housing. The gas supplied at the predetermined velocity to the housing through the inlet conduit and the nozzle in an annular shape traverses the gap between the first and second electrodes and entrains low velocity gas within the housing decreasing the velocity of the gas supplied to the housing and increasing the diameter of the annular shape. The venturi disposed within the second electrode recirculates a large volume of gas to clean and cool the surface of the electrodes.

  4. Rarefied Gas Flows Induced through a Pair of Parallel Meshes with Different Temperatures

    NASA Astrophysics Data System (ADS)

    Sugimoto, H.; Kawakami, S.; Moriuchi, K.

    2008-12-01

    A simple method to form micro-channels that induce a rarefied gas flow by the effect of the temperature field is proposed. A pair of parallel wire meshes, one is heated and the other is unheated, induces a gas flow through the pair of meshes in the direction from unheated mesh to heated mesh. Three test devices with different diameters, 1 mm, 100 μm, and 25 μm, of the wire of the mesh, have been devised and the flow through the device is detected by a thin film or a small windmill for various pressures of the gas. The flow is observed in a range of the pressure where the mean free path of gas molecules is close to the scale of the mesh structure, e.g., the diameter of the wire. It is extended to a wider range of the pressure in the device using combined meshes consisting of coarser and finer mesh.

  5. Gas phase dispersion in compost as a function of different water contents and air flow rates

    NASA Astrophysics Data System (ADS)

    Sharma, Prabhakar; Poulsen, Tjalfe G.

    2009-07-01

    Gas phase dispersion in a natural porous medium (yard waste compost) was investigated as a function of gas flow velocity and compost volumetric water content using oxygen and nitrogen as tracer gases. The compost was chosen because it has a very wide water content range and because it represents a wide range of porous media, including soils and biofilter media. Column breakthrough curves for oxygen and nitrogen were measured at relatively low pore gas velocities, corresponding to those observed in for instance soil vapor extraction systems or biofilters for air cleaning at biogas plants or composting facilities. Total gas mechanical dispersion-molecular diffusion coefficients were fitted from the breakthrough curves using a one-dimensional numerical solution to the advection-dispersion equation and used to determine gas dispersivities at different volumetric gas contents. The results showed that gas mechanical dispersion dominated over molecular diffusion with mechanical dispersion for all water contents and pore gas velocities investigated. Importance of mechanical dispersion increased with increasing pore gas velocity and compost water content. The results further showed that gas dispersivity was relatively constant at high values of compost gas-filled porosity but increased with decreasing gas-filled porosity at lower values of gas-filled porosity. Results finally showed that measurement uncertainty in gas dispersivity is generally highest at low values of pore gas velocity.

  6. Comparing the equivalent particle number density distribution of gas and plasma flow fields.

    PubMed

    Chen, Yun-yun; Zhang, Ying-ying; Zhang, Cheng-yi; Li, Zhen-hua

    2013-04-20

    In this paper, the equivalent particle number density distribution of gas and plasma flow fields is investigated. For the purpose of facilitating comparison, argon gas and argon arc plasma are chosen as practical examples for experiment. The equivalent particle number density distributions of the argon gas and argon arc plasma are reconstructed from the experimentally measured refractive index distributions obtained by moiré tomography, while five cross sections, which are 7, 8.5, 10, 11.5, and 13 mm away from the jet nozzle are chosen for practical calculation and comparison. In experiment, the probe wavelength and the export pressure of argon gas and argon arc plasma are the same. The experimental results manifest that (1) the equivalent particle number density decreases with the distance away from the jet nozzle of the gas flow field, while (2) the equivalent particle number density of the plasma flow field has a different variation. Finally, the experimental results are theoretically explained and analyzed.

  7. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1998-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  8. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1998-06-16

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

  9. Dynamic gas slippage: A unique dual-mechanism approach to the flow of gas in tight formations

    SciTech Connect

    Ertekin; King, G.R.; Schwerer, F.C.

    1983-10-01

    A mathematical formulation, applicable to both numerical simulation and transient well analysis, describing the flow of gas in very tight (k < 0.1 md) porous media has been developed. Unique to this formulation is the dual-mechanism transport of gas. In this formulation gas is assumed to be traveling under the influence of two fields: a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's Law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's law (inertial-turbulent effects are ignored). The combination of these two flow mechanisms rigorously yields a composition, pressure and saturation dependent slippage factor. The pressure dependence arises from treating the gas as a real gas. The dynamic slippage derived from this formulation is found to be most applicable in reservoirs with permeabilities less than or equal to 0.01 md. The results from this study indicate that in reservoirs of this type, differences between recoveries after ten years of production using the dynamic slip described in this paper and constant slip approaches were as great as 10% depending on the initial gas saturation. If an economic production rate is considered, differences as great as 30 can be expected.

  10. Dynamic gas slippage: A unique dual-mechanism approach to the flow of gas in tight formations

    SciTech Connect

    Ertekin, T.; King, G.R.; Schwerer, F.C.

    1986-02-01

    A mathematical formulation, applicable to both numerical simulation and transient well analysis that describes the flow of gas in very tight porous media and includes a dual-mechanism transport of gas is developed. Gas is assumed to be traveling under the influence of a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's law (inertial/turbulent effects are ignored). The combination of these two flow mechanisms rigorously yields a composition-, pressure-, and saturation-dependent slippage factor. The pressure dependence arises from treating the gas as a real gas. The derived dynamic slippage is most applicable in reservoirs with permeabilities less than or equal to0.01 md. The results indicate that in reservoirs of this type, differences between recoveries after 10 years of production with the dynamic-slip and constant-slip approaches were as great as 10%, depending on the initial gas saturation. If an economic production rate is considered, differences as great as 30% can be expected.

  11. WNG develops Order 636-compatible EFM. [Computerized flow measurements for gas pipelines

    SciTech Connect

    Ellison, C. ); Wallace, D. )

    1994-02-01

    This paper describes the development of a comprehensive flow measurement system by Williams Natural Gas to meet the challenges resulting from Order 636. These flow measurement systems allow for a remote control method of performing custody transfer for major interstate gas pipeline systems. This paper describes the design and operational control equipment for these systems along with a description of the communications networks and software.

  12. Aerodynamic improvement of the assembly through which gas conduits are taken into a smoke stack by simulating gas flow on a computer

    NASA Astrophysics Data System (ADS)

    Prokhorov, V. B.; Fomenko, M. V.; Grigor'ev, I. V.

    2012-06-01

    Results from computer simulation of gas flow motion for gas conduits taken on one and two sides into the gas-removal shaft of a smoke stack with a constant cross section carried out using the SolidWorks and FlowVision application software packages are presented.

  13. The Gas Flow from the Gas Attenuator to the Beam Line

    SciTech Connect

    Ryutov, D.D.

    2010-12-03

    The gas leak from the gas attenuator to the main beam line of the Linac Coherent Light Source has been evaluated, with the effect of the Knudsen molecular beam included. It has been found that the gas leak from the gas attenuator of the present design, with nitrogen as a working gas, does not exceed 10{sup -5} torr x l/s even at the highest pressure in the main attenuation cell (20 torr).

  14. Brush Seal Would Impede Flow Of Hot Gas

    NASA Technical Reports Server (NTRS)

    Carroll, Paul F.; Easter, Barry P.

    1993-01-01

    Proposed brush seal helps prevent recirculating flow of hot combustion gases from reaching bellows seal located deep in gap in wall of combustion chamber. More durable, more tolerant of irregularities, and easier to install. Seals also helpful in impeding deleterious flows of hot gases in other combustion chambers such as those of furnaces and turbomachines.

  15. Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model

    NASA Astrophysics Data System (ADS)

    Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

    2016-09-01

    To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results.

  16. Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model

    PubMed Central

    Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

    2016-01-01

    To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results. PMID:27587293

  17. Study of Gas Flow Characteristics in Tight Porous Media with a Microscale Lattice Boltzmann Model.

    PubMed

    Zhao, Jianlin; Yao, Jun; Zhang, Min; Zhang, Lei; Yang, Yongfei; Sun, Hai; An, Senyou; Li, Aifen

    2016-01-01

    To investigate the gas flow characteristics in tight porous media, a microscale lattice Boltzmann (LB) model with the regularization procedure is firstly adopted to simulate gas flow in three-dimensional (3D) digital rocks. A shale digital rock and a sandstone digital rock are reconstructed to study the effects of pressure, temperature and pore size on microscale gas flow. The simulation results show that because of the microscale effect in tight porous media, the apparent permeability is always higher than the intrinsic permeability, and with the decrease of pressure or pore size, or with the increase of temperature, the difference between apparent permeability and intrinsic permeability increases. In addition, the Knudsen numbers under different conditions are calculated and the results show that gas flow characteristics in the digital rocks under different Knudsen numbers are quite different. With the increase of Knudsen number, gas flow in the digital rocks becomes more uniform and the effect of heterogeneity of the porous media on gas flow decreases. Finally, two commonly used apparent permeability calculation models are evaluated by the simulation results and the Klinkenberg model shows better accuracy. In addition, a better proportionality factor in Klinkenberg model is proposed according to the simulation results. PMID:27587293

  18. Multilayer Badges Indicate Depths Of Ion Sputter Etches

    NASA Technical Reports Server (NTRS)

    Beattie, J. R.; Matossian, J. N.; Garvin, H. L.

    1994-01-01

    Multilayer badges devised to provide rapid, in-place indications of ion sputter etch rates. Badges conceived for use in estimating ion erosion of molybdenum electrodes used in inert-gas ion thrustors. Concept adapted to measure ion erosion in industrial sputter etching processes used for manufacturing of magnetic, electronic, and optical devices. Badge etched when bombarded by energetic ions. Badge layers exposed using mask. Contrast between layers facilitates counting of layers to determine etch depth.

  19. Accurate quadrupole MS peak reconstruction in optimized gas-flow comprehensive two-dimensional gas chromatography.

    PubMed

    Tranchida, Peter Quinto; Purcaro, Giorgia; Sciarrone, Danilo; Dugo, Paola; Dugo, Giovanni; Mondello, Luigi

    2010-09-01

    In the present research, a split-flow comprehensive 2-D GC-quadrupole MS (qMS) method was developed using: a primary apolar 30 m×0.25 mm id×0.25 μm d(f) capillary linked, via a T-union, to a secondary polar 1.0 m×0.05 mm id×0.05 μm d(f) capillary and to a 0.10 m×0.05 mm id×0.05 μm d(f) uncoated column segment. The GC×GC-qMS instrument was equipped with two GC ovens and a loop-type modulator. The polar column was connected to the MS, whereas the uncoated column directed most of the first-dimension effluent to waste and enabled the generation of optimum gas velocities in both dimensions, namely circa 20 and 80 cm/s in the first and second dimensions, respectively. The rapid-scanning qMS was operated at a scan speed of 10,000 amu/s, a 25-Hz data acquisition frequency (scan time+interscan time: 40 ms), and with a normal GC mass range (m/z 40-360). Chromatography bands at the second-dimension outlet were never less than 360 ms wide (6σ), enabling the acquisition of at least 10 spectra/peak.

  20. Measurement of gas yields and flow rates using a custom flowmeter

    USGS Publications Warehouse

    Circone, S.; Kirby, S.H.; Pinkston, J.C.; Stern, L.A.

    2001-01-01

    A simple gas collection apparatus based on the principles of a Torricelli tube has been designed and built to measure gas volume yields and flow rates. This instrument is routinely used to monitor and collect methane gas released during methane hydrate dissociation experiments. It is easily and inexpensively built, operates at ambient pressures and temperatures, and measures gas volumes of up to 7 L to a precision of about 15 ml (about 0.0025 mol). It is capable of measuring gas flow rates varying from more than 103 to less than 10-1 ml/min during gas evolution events that span minutes to several days. We have obtained a highly reproducible hydrate number of n=5.891 with a propagated uncertainty of ??0.020 for synthetic methane hydrate. ?? 2001 American Institute of Physics.

  1. Magnetic resonance velocity imaging of liquid and gas two-phase flow in packed beds.

    PubMed

    Sankey, M H; Holland, D J; Sederman, A J; Gladden, L F

    2009-02-01

    Single-phase liquid flow in porous media such as bead packs and model fixed bed reactors has been well studied by MRI. To some extent this early work represents the necessary preliminary research to address the more challenging problem of two-phase flow of gas and liquid within these systems. In this paper, we present images of both the gas and liquid velocities during stable liquid-gas flow of water and SF(6) within a packing of 5mm spheres contained within columns of diameter 40 and 27 mm; images being acquired using (1)H and (19)F observation for the water and SF(6), respectively. Liquid and gas flow rates calculated from the velocity images are in agreement with macroscopic flow rate measurements to within 7% and 5%, respectively. In addition to the information obtained directly from these images, the ability to measure liquid and gas flow fields within the same sample environment will enable us to explore the validity of assumptions used in numerical modelling of two-phase flows. PMID:19059796

  2. Physical Properties of Titanium Oxide Thin Films Prepared by DC Magnetron Sputtering: Influence Substrate Temperature and O2/Ar in the Gas Mixture

    NASA Astrophysics Data System (ADS)

    Hantehzadeh, M. R.; Amouha, M. Amou; Solaymani, S.; Osati, T.; Ghobadi, B.

    2013-08-01

    Titanium oxide thin film compounds were grown on p-type Si (100) and BK7 glass as substrate using reactive DC magnetron sputtering. The effect of temperature growth on structural, optical and morphological properties was investigated. By means of X-ray diffraction (XRD) the phase composition was characterized. UV-Vis-NIR spectroscopy was used for reflection and transmission measurements of deposited thin film layers. Atomic force microscopy was used to evaluate and compute the surface roughness changes for different temperatures growth. The XRD results show that the temperature growth effects on the phase formation and structure. Increasing the substrate growth temperature would result in change of film thickness due to different phase and structure formation. The calculated band gap from optical measurements of the thin films shows a decrease at higher substrate temperature growth.

  3. Mathematical modelling of the liquid atomization process by cocurrent gas flow

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Boiko, V. M.; Goldin, V. D.; Maslov, E. A.; Orlov, S. E.; Poplavskiy, S. V.; Usanina, A. S.; Zharova, I. K.

    2016-04-01

    This paper focuses on the physical-mathematical model of liquid atomization in the spray pattern of an ejection nozzle. A flow field of a gas phase behind the nozzle section is computed using the Ansys Fluent package. Dynamics of molten metal droplets in the gas phase within a trajectory approach is calculated. Using the presented model, numerical calculation results are given.

  4. 40 CFR 92.117 - Gas meter or flow instrumentation calibration, particulate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Gas meter or flow instrumentation calibration, particulate measurement. 92.117 Section 92.117 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR POLLUTION FROM LOCOMOTIVES AND LOCOMOTIVE ENGINES Test Procedures § 92.117 Gas...

  5. A study of the critical nozzle for flow rate measurement of high-pressure hydrogen gas

    NASA Astrophysics Data System (ADS)

    Kim, H. D.; Lee, J. H.; Park, K. A.; Setoguchi, T.; Matsuo, S.

    2007-03-01

    The mass flow rate measurement using a critical nozzle shows the validity of the inviscid theory, indicating that the discharge coefficient increases and approaches unity as the Reynolds number increases under the ideal gas law. However, when the critical nozzle measures the mass flow rate of a real gas such as hydrogen at a pressure of hundreds bar, the discharge coefficient exceeds unity, and the real gas effects should be taken into account. The present study aims at investigating the flow features of the critical nozzle using high-pressured hydrogen gas. The axisymmetric, compressible Navier-Stokes computation is employed to simulate the critical nozzle flow, and a fully implicit finite volume method is used to discretize the governing equation system. The real gas effects are simulated to consider the intermolecular forces, which account for the possibility of liquefying hydrogen gas. The computational results are compared with past experimental data. It has been found that the coefficient of discharge for real gas can be corrected properly below unity adopting the real gas assumption.

  6. Flow modulation comprehensive two-dimensional gas chromatography-mass spectrometry using ≈4 mL min(-1) gas flows.

    PubMed

    Franchina, Flavio A; Maimone, Mariarosa; Tranchida, Peter Q; Mondello, Luigi

    2016-04-01

    The main objective of the herein described research was focused on performing satisfactory flow modulation (FM), in comprehensive two-dimensional gas chromatography-mass spectrometry (GC×GC-MS), using an MS-compatible second-dimension gas flow of approx. 4 mL min(-1). The FM model used was based on that initially proposed by Seeley et al. [3]. The use of limited gas flows was enabled through fine tuning of the FM parameters, in particular the duration of the re-injection (or flushing) process. Specifically, the application of a long re-injection period (i.e., 700 ms) enabled efficient accumulation-loop flushing with gas flows of about 4 mL min(-1). It was possible to apply such extended re-injection periods by using different restrictor lengths in the connections linking the modulator to the auxiliary pressure source. FM GC×GC-MS applications were performed on a mixture containing C9-10 alkanes, and on a sample of essential oil. GC×GC-MS sensitivity was compared with that attained by using conventional GC-MS analysis, in essential oil applications. It was observed that signal intensities were, in general, considerably higher in the FM GC×GC-MS experiments.

  7. Gas-Liquid flow characterization in bubble columns with various gas-liquid using electrical resistance tomography

    NASA Astrophysics Data System (ADS)

    Jin, Haibo; Yuhuan, Han; Suohe, Yang

    2009-02-01

    Electrical resistance tomography (ERT) is an advanced and new detecting technique that can measure and monitor the parameters of two-phase flow on line, such as gas-liquid bubble column. It is fit for the industrial process where the conductible medium serves as the disperse phase to present the key bubble flow characteristics in multi-phase medium. Radial variation of the gas holdup and mean holdups are investigated in a 0.160 m i. d. bubble column using ERT with two axial locations (Plane 1 and Plane 2). In all the experiments, air was used as the gas phase, tap water as liquid phase, and a series of experiments were done by adding KCl, ethanol, oil sodium, and glycerol to change liquid conductivity, liquid surface tension and viscosity. The superficial gas velocity was varied from 0.02 to 0.2 m/s. The effect of conductivity, surface tension, viscosity on the mean holdups and radial gas holdup distribution is discussed. The results showed that the gas holdup decrease with the increase of surface tension and increase with the increase of viscosity. Meanwhile, the settings of initial liquid conductivity slightly influence the gas holdup values, and the experimental data increases with the increase of the initial setting values in the same conditions.

  8. Gas Flow Tightly Coupled to Elastoplastic Geomechanics for Tight- and Shale-Gas Reservoirs: Material Failure and Enhanced Permeability

    SciTech Connect

    Kim, Jihoon; Moridis, George J.

    2014-12-01

    We investigate coupled flow and geomechanics in gas production from extremely low permeability reservoirs such as tight and shale gas reservoirs, using dynamic porosity and permeability during numerical simulation. In particular, we take the intrinsic permeability as a step function of the status of material failure, and the permeability is updated every time step. We consider gas reservoirs with the vertical and horizontal primary fractures, employing the single and dynamic double porosity (dual continuum) models. We modify the multiple porosity constitutive relations for modeling the double porous continua for flow and geomechanics. The numerical results indicate that production of gas causes redistribution of the effective stress fields, increasing the effective shear stress and resulting in plasticity. Shear failure occurs not only near the fracture tips but also away from the primary fractures, which indicates generation of secondary fractures. These secondary fractures increase the permeability significantly, and change the flow pattern, which in turn causes a change in distribution of geomechanical variables. From various numerical tests, we find that shear failure is enhanced by a large pressure drop at the production well, high Biot's coefficient, low frictional and dilation angles. Smaller spacing between the horizontal wells also contributes to faster secondary fracturing. When the dynamic double porosity model is used, we observe a faster evolution of the enhanced permeability areas than that obtained from the single porosity model, mainly due to a higher permeability of the fractures in the double porosity model. These complicated physics for stress sensitive reservoirs cannot properly be captured by the uncoupled or flow-only simulation, and thus tightly coupled flow and geomechanical models are highly recommended to accurately describe the reservoir behavior during gas production in tight and shale gas reservoirs and to smartly design production

  9. Experimental and theoretical studies of isothermal upward gas-liquid flows in vertical tubes

    SciTech Connect

    Fernandes, R.C.

    1981-01-01

    In two-phase flow technolgy, two important problems exist which must be solved as a function of the various physical and system parameters associated with the phenomenon, and which stand as prerequisites for proper modelling of two-phase processes: Prediction of the flow pattern under existing operating conditions and prediction of the holdup for each given flow pattern. Modelling studies of steady isothermal upward gas-liquid flows in vertical pipes, at low pressures, were undertaken. Experimental data on liquid holdup over a wide range of flow rates were taken for all observed flow patterns-bubbly, slug, churn, and annular - by means of a specially designed Quick-Closing Valves System. This technique also allowed the detection of a unique phenomenon occurring in the form of fast-flowing slugs of gas-liquid mixture, in both the churn and annular flow patterns, which was called the lump phenomenon. The lump holdup was measured and a qualitative theory regarding the nature, formation and propagation of these structures was proposed. A photographic method was applied to the slug flow pattern in order to determine both the rise velocity and length of Taylor bubbles and liquid slugs characteristic of this flow regime. Assisted by the measured data, flow pattern-based physical models were developed for predicting holdup of bubbly flows and the detailed structure of slug flows. The latter was accomplished by means of a fairly complete analysis which enabled the prediction of several variables of interest such as void fractions, velocities, film thicknesses and the length ratio between Taylor bubbles and liquid slugs. The average holdup for churn flow was predicted by directly applying the slug flow model to that flow pattern. A simplified framework for calculating the holdup in annular flows was also proposed. The comparison between theory and experiment showed that for bubbly, slug and churn flows the predicted results are in good agreement with the data.

  10. Rarefied gas flow simulations using high-order gas-kinetic unified algorithms for Boltzmann model equations

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Hui; Peng, Ao-Ping; Zhang, Han-Xin; Yang, Jaw-Yen

    2015-04-01

    This article reviews rarefied gas flow computations based on nonlinear model Boltzmann equations using deterministic high-order gas-kinetic unified algorithms (GKUA) in phase space. The nonlinear Boltzmann model equations considered include the BGK model, the Shakhov model, the Ellipsoidal Statistical model and the Morse model. Several high-order gas-kinetic unified algorithms, which combine the discrete velocity ordinate method in velocity space and the compact high-order finite-difference schemes in physical space, are developed. The parallel strategies implemented with the accompanying algorithms are of equal importance. Accurate computations of rarefied gas flow problems using various kinetic models over wide ranges of Mach numbers 1.2-20 and Knudsen numbers 0.0001-5 are reported. The effects of different high resolution schemes on the flow resolution under the same discrete velocity ordinate method are studied. A conservative discrete velocity ordinate method to ensure the kinetic compatibility condition is also implemented. The present algorithms are tested for the one-dimensional unsteady shock-tube problems with various Knudsen numbers, the steady normal shock wave structures for different Mach numbers, the two-dimensional flows past a circular cylinder and a NACA 0012 airfoil to verify the present methodology and to simulate gas transport phenomena covering various flow regimes. Illustrations of large scale parallel computations of three-dimensional hypersonic rarefied flows over the reusable sphere-cone satellite and the re-entry spacecraft using almost the largest computer systems available in China are also reported. The present computed results are compared with the theoretical prediction from gas dynamics, related DSMC results, slip N-S solutions and experimental data, and good agreement can be found. The numerical experience indicates that although the direct model Boltzmann equation solver in phase space can be computationally expensive

  11. Self-gravitating gas flow in barred spiral galaxies

    NASA Technical Reports Server (NTRS)

    Huntley, J. M.

    1980-01-01

    A series of two-dimensional numerical experiments is performed in order to test the response of an isothermal, self-gravitating gas disk to a uniformly rotating, barlike gravitational potential. The barlike potential is an equilibrium stellar model from the n-body calculations of Miller and Smith (1979). In the bar-dominated, central regions of the disk, a gas bar whose phase depends primarily on the location of principal resonances in the disk is formed. This response can be understood in terms of orbit-crowding effects. In the gas-dominated outer regions of the disk, two-armed trailing spiral waves are formed. The local pitch angle of these waves increases with increasing fractional gas mass. These self-gravitating gas waves are not self-sustaining. They are driven from the ends of equilibrium stellar bars, and their phase does not depend on the location of resonances in the disk. The relevance of these self-gravitating waves to observations and models of barred spiral galaxies is discussed. It is concluded that these waves and their associated ringlike structures may be consistent with the morphological distribution of gas features in barred spiral galaxies.

  12. Approximate Solution for Choked Flow in Gas Seal Pads

    NASA Technical Reports Server (NTRS)

    Fleming, David P.

    2004-01-01

    Previous analyses of high pressure seals have considered adiabatic flow with friction but neglected effects of seal rotation. Most of this work analyzed a one-dimensional flow field. This works well to calculate stiffness and leakage of full circular seals, either face seals or annular ring seals. However, it cannot provide accurate results for a rectangular seal pad with its strongly two-dimensional flow field and its reliance on hydrodynamic forces to maintain a full fluid film. On the other hand, solutions of Reynolds lubrication equation have been obtained for the two-dimensional flow in a seal pad. But these solutions do not account for choking which occurs at high seal pressure ratios, nor do they consider the pressure loss that occurs in the entrance region of the flow field. The aim of the present work is to build on the Reynolds equation solution by use of an approximate choked flow analysis. This will account for the pressure losses in the flow entrance region, ensure that fluid velocities remain subsonic, and enable fluid inertial effects within the pad film to be accounted for. Results show that, in general, fluid inertia acts to decrease pad film load capacity and leakage, and increase film stiffness.

  13. Interstellar Gas Flow Vector and Temperature Determination over 5 Years of IBEX Observations

    NASA Astrophysics Data System (ADS)

    Möbius, E.; Bzowski, M.; Fuselier, S. A.; Heirtzler, D.; Kubiak, M. A.; Kucharek, H.; Lee, M. A.; Leonard, T.; McComas, D. J.; Schwadron, N.; Sokół, J. M.; Wurz, P.

    2015-01-01

    The Interstellar Boundary Explorer (IBEX) observes the interstellar neutral gas flow trajectories at their perihelion in Earth's orbit every year from December through early April, when the Earth's orbital motion is into the oncoming flow. These observations have defined a narrow region of possible, but very tightly coupled interstellar neutral flow parameters, with inflow speed, latitude, and temperature as well-defined functions of inflow longitude. The best- fit flow vector is different by ≈ 3° and lower by ≈ 3 km/s than obtained previously with Ulysses GAS, but the temperature is comparable. The possible coupled parameter space reaches to the previous flow vector, but only for a substantially higher temperature (by ≈ 2000 K). Along with recent pickup ion observations and including historical observations of the interstellar gas, these findings have led to a discussion, whether the interstellar gas flow into the solar system has been stable or variable over time. These intriguing possibilities call for more detailed analysis and a longer database. IBEX has accumulated observations over six interstellar flow seasons. We review key observations and refinements in the analysis, in particular, towards narrowing the uncertainties in the temperature determination. We also address ongoing attempts to optimize the flow vector determination through varying the IBEX spacecraft pointing and discuss related implications for the local interstellar cloud and its interaction with the heliosphere.

  14. DEVELOPMENT OF LOW-DIFFUSION FLUX-SPLITTING METHODS FOR DENSE GAS-SOLID FLOWS

    EPA Science Inventory

    The development of a class of low-diffusion upwinding methods for computing dense gas-solid flows is presented in this work. An artificial compressibility/low-Mach preconditioning strategy is developed for a hyperbolic two-phase flow equation system consisting of separate solids ...

  15. Radiation-transport method to simulate noncontinuum gas flows for MEMS devices.

    SciTech Connect

    Gallis, Michail A.; Torczynski, John Robert

    2004-01-01

    A Micro Electro Mechanical System (MEMS) typically consists of micron-scale parts that move through a gas at atmospheric or reduced pressure. In this situation, the gas-molecule mean free path is comparable to the geometric features of the microsystem, so the gas flow is noncontinuum. When mean-free-path effects cannot be neglected, the Boltzmann equation must be used to describe the gas flow. Solution of the Boltzmann equation is difficult even for the simplest case because of its sevenfold dimensionality (one temporal dimension, three spatial dimensions, and three velocity dimensions) and because of the integral nature of the collision term. The Direct Simulation Monte Carlo (DSMC) method is the method of choice to simulate high-speed noncontinuum flows. However, since DSMC uses computational molecules to represent the gas, the inherent statistical noise must be minimized by sampling large numbers of molecules. Since typical microsystem velocities are low (< 1 m/s) compared to molecular velocities ({approx}400 m/s), the number of molecular samples required to achieve 1% precision can exceed 1010 per cell. The Discrete Velocity Gas (DVG) method, an approach motivated by radiation transport, provides another way to simulate noncontinuum gas flows. Unlike DSMC, the DVG method restricts molecular velocities to have only certain discrete values. The transport of the number density of a velocity state is governed by a discrete Boltzmann equation that has one temporal dimension and three spatial dimensions and a polynomial collision term. Specification and implementation of DVG models are discussed, and DVG models are applied to Couette flow and to Fourier flow. While the DVG results for these benchmark problems are qualitatively correct, the errors in the shear stress and the heat flux can be order-unity even for DVG models with 88 velocity states. It is concluded that the DVG method, as described herein, is not sufficiently accurate to simulate the low-speed gas flows

  16. Open-source MFIX-DEM software for gas-solids flows: Part I verification studies

    SciTech Connect

    Garg, Rahul; Galvin, Janine; Li, Tingwen; Pannala, Sreekanth

    2012-01-01

    With rapid advancements in computer hardware, it is now possible to perform large simulations of granular flows using the Discrete Element Method (DEM). As a result, solids are increasingly treated in a discrete Lagrangian fashion in the gas solids flow community. In this paper, the open-source MFIX-DEM software is described that can be used for simulating the gas solids flow using an Eulerian reference frame for the continuum fluid and a Lagrangian discrete framework (Discrete Element Method) for the particles. This method is referred to as the continuum discrete method (CDM) to clearly make a distinction between the ambiguity of using a Lagrangian or Eulerian reference for either continuum or discrete formulations. This freely available CDM code for gas solids flows can accelerate the research in computational gas solids flows and establish a baseline that can lead to better closures for the continuum modeling (or traditionally referred to as two fluid model) of gas solids flows. In this paper, a series of verification cases is employed which tests the different aspects of the code in a systematic fashion by exploring specific physics in gas solids flows before exercising the fully coupled solution on simple canonical problems. It is critical to have an extensively verified code as the physics is complex with highly-nonlinear coupling, and it is difficult to ascertain the accuracy of the results without rigorous verification. These series of verification tests set the stage not only for rigorous validation studies (performed in part II of this paper) but also serve as a procedure for testing any new developments that couple continuum and discrete formulations for gas solids flows.

  17. Numerical modeling of gas-liquid flows in mini- and microchannels

    NASA Astrophysics Data System (ADS)

    Guzei, D. V.; Minakov, A. V.; Pryazhnikov, M. I.; Dekterev, A. A.

    2015-01-01

    The paper presents the results of testing a methodology for calculating two-phase flows in mini- and microchannels. The numerical methodology is based on the known fluid-in-cell method (VOF method) and the CSF procedure to account for surface tension forces. Solutions of several test problems of two-phase flow in microchannels, including the water-oil emulsion flow and gas-liquid flow in microchannels of the T-type and the stationary slug flow in a circular minichannel, were considered with the aid of this technique. Comparisons of numerical results with experimental data were carried out. A good agreement between the results was obtained.

  18. Rock matrix and fracture analysis of flow in western tight gas sands: Annual report, Phase 3

    SciTech Connect

    Dandge, V.; Graham, M.; Gonzales, B.; Coker, D.

    1987-12-01

    Tight gas sands are a vast future source of natural gas. These sands are characterized as having very low porosity and permeability. The main resource development problem is efficiently extracting the gas from the reservoir. Future production depends on a combination of gas price and technological advances. Gas production can be enhanced by fracturing. Studies have shown that many aspects of fracture design and gas production are influenced by properties of the rock matrix. Computer models for stimulation procedures require accurate knowledge of flow properties of both the rock matrix and the fractured regions. In the proposed work, these properties will be measured along with advanced core analysis procedure aimed at understanding the relationship between pore structure and properties. The objective of this project is to develop reliable core analysis techniques for measuring the petrophysical properties of tight gas sands. Recent research has indicated that the flow conditions in the reservoir can be greatly enhanced by the presence of natural fractures, which serve as a transport path for gas from the less permeable matrix. The study is mainly concerned with the dependence of flow in tight gas matrix and healed tectonic fractures on water saturation and confining pressure. This dependency is to be related to the detailed pore structure of tight sands as typified by cores recovered in the Multi-Well experiment. 22 refs., 34 figs., 9 tabs.

  19. A transient method for measuring the gas volume fraction in a mixed gas-liquid flow using acoustic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Dehua; Wang, Xiuming; Che, Chengxuan; Cong, Jiansheng; Xu, Delong; Wang, Xiaomin

    2010-08-01

    In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.

  20. Characterization of indium tin oxide films by RF-assisted DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Houng, Boen; Wang, Adam

    2012-05-01

    A unique design of RF (radio frequency) assisted DC (direct current) sputter was employed to deposit ITO (indium tin oxide) films on PET (polyethylene terephtalate) substrate. Effects of different RF portions of total power and oxygen gas flow on the properties of the films were investigated. It was found that the films became denser as the applied RF portion of the total power increased. This is due to higher momentum energy transfer by impinging ions increasing adatom diffusion on the films. Thus, a larger grained and less porous microstructure was presented in the films deposited at higher RF portions of the total power. However, a rougher surface morphology and minor crystallization was also found in the films prepared at 100% RF power. By wisely adjusting to a 50% RF portion of the total power, the electrical resistivity can reach a minimum value of 5.4 × 10-4 Ω cm associated with the carrier concentration of 7.0 × 1020 cm-3 and mobility of 17.4 cm2 V-1 s-1, respectively. In addition, the oxygen gas concentration in the sputtering chamber was found to play a key role in determining the quality of the films. As oxygen gas flowed at 2 sccm, the electrical resistivity was decreased to 3.9 × 10-4 Ω cm at a 50% RF portion of the total power. The electrical conduction mechanism, based on the grain boundary scattering, was correlated to the microstructure of the films in terms of grain size.

  1. Sputter coating of microspherical substrates by levitation

    DOEpatents

    Lowe, A.T.; Hosford, C.D.

    Microspheres are substantially uniformly coated with metals or nonmetals by simltaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons,, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  2. Sputter coating of microspherical substrates by levitation

    DOEpatents

    Lowe, Arthur T.; Hosford, Charles D.

    1981-01-01

    Microspheres are substantially uniformly coated with metals or nonmetals by simultaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure 12 comprising a parallel array of upwardly projecting individual gas outlets 16 is machined out to form a dimple 11. Glass microballoons, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  3. Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

    NASA Astrophysics Data System (ADS)

    Wißdorf, Walter; Müller, David; Brachthäuser, Yessica; Langner, Markus; Derpmann, Valerie; Klopotowski, Sebastian; Polaczek, Christine; Kersten, Hendrik; Brockmann, Klaus; Benter, Thorsten

    2016-09-01

    In this work, the characteristics of gas flow in inlet capillaries are examined. Such inlet capillaries are widely used as a first flow restriction stage in commercial atmospheric pressure ionization mass spectrometers. Contrary to the common assumption, we consider the gas flow in typical glass inlet capillaries with 0.5 to 0.6 mm inner diameters and lengths about 20 cm as transitional or turbulent. The measured volume flow of the choked turbulent gas stream in such capillaries is 0.8 L·min-1 to 1.6 L·min-1 under typical operation conditions, which is in good agreement to theoretically calculated values. Likewise, the change of the volume flow in dependence of the pressure difference along the capillary agrees well with a theoretical model for turbulent conditions as well as with exemplary measurements of the static pressure inside the capillary channel. However, the results for the volume flow of heated glass and metal inlet capillaries are neither in agreement with turbulent nor with laminar models. The velocity profile of the neutral gas in a quartz capillary with an inner diameter similar to commercial inlet capillaries was experimentally determined with spatially resolved ion transfer time measurements. The determined gas velocity profiles do not contradict the turbulent character of the flow. Finally, inducing disturbances of the gas flow by placing obstacles in the capillary channel is found to not change the flow characteristics significantly. In combination the findings suggest that laminar conditions inside inlet capillaries are not a valid primary explanation for the observed high ion transparency of inlet capillaries under common operation conditions.

  4. Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions.

    PubMed

    Wißdorf, Walter; Müller, David; Brachthäuser, Yessica; Langner, Markus; Derpmann, Valerie; Klopotowski, Sebastian; Polaczek, Christine; Kersten, Hendrik; Brockmann, Klaus; Benter, Thorsten

    2016-09-01

    In this work, the characteristics of gas flow in inlet capillaries are examined. Such inlet capillaries are widely used as a first flow restriction stage in commercial atmospheric pressure ionization mass spectrometers. Contrary to the common assumption, we consider the gas flow in typical glass inlet capillaries with 0.5 to 0.6 mm inner diameters and lengths about 20 cm as transitional or turbulent. The measured volume flow of the choked turbulent gas stream in such capillaries is 0.8 L·min(-1) to 1.6 L·min(-1) under typical operation conditions, which is in good agreement to theoretically calculated values. Likewise, the change of the volume flow in dependence of the pressure difference along the capillary agrees well with a theoretical model for turbulent conditions as well as with exemplary measurements of the static pressure inside the capillary channel. However, the results for the volume flow of heated glass and metal inlet capillaries are neither in agreement with turbulent nor with laminar models. The velocity profile of the neutral gas in a quartz capillary with an inner diameter similar to commercial inlet capillaries was experimentally determined with spatially resolved ion transfer time measurements. The determined gas velocity profiles do not contradict the turbulent character of the flow. Finally, inducing disturbances of the gas flow by placing obstacles in the capillary channel is found to not change the flow characteristics significantly. In combination the findings suggest that laminar conditions inside inlet capillaries are not a valid primary explanation for the observed high ion transparency of inlet capillaries under common operation conditions. Graphical Abstract ᅟ. PMID:27245455

  5. Influence of NO-containing gas flow on various parameters of energy metabolism in erythrocytes.

    PubMed

    Martusevich, A K; Solov'yova, A G; Peretyagin, S P; Karelin, V I; Selemir, V D

    2014-11-01

    We studied the influence of NO-containing gas phase on some parameters of energy metabolism in human erythrocytes. Whole blood samples were aerated with gas flows from the Plazon instrument (NO concentrations 800 and 80 ppm) and from the experimental generator (75 ppm). Activity of lactate dehydrogenase in direct and reverse reactions, lactate level, and a number of derived coefficients were estimated. Treatment of blood with 800 ppm NO inhibited erythrocyte energy metabolism, and its 10-fold dilution attenuated the effect. The use of ROS-free gas flow containing 75 ppm of NO promoted optimization of the process under investigation.

  6. Influence of NO-containing gas flow on various parameters of energy metabolism in erythrocytes.

    PubMed

    Martusevich, A K; Solov'yova, A G; Peretyagin, S P; Karelin, V I; Selemir, V D

    2014-11-01

    We studied the influence of NO-containing gas phase on some parameters of energy metabolism in human erythrocytes. Whole blood samples were aerated with gas flows from the Plazon instrument (NO concentrations 800 and 80 ppm) and from the experimental generator (75 ppm). Activity of lactate dehydrogenase in direct and reverse reactions, lactate level, and a number of derived coefficients were estimated. Treatment of blood with 800 ppm NO inhibited erythrocyte energy metabolism, and its 10-fold dilution attenuated the effect. The use of ROS-free gas flow containing 75 ppm of NO promoted optimization of the process under investigation. PMID:25403392

  7. INVESTIGATION ON THE OSCILLATING GAS FLOW ALONG AN INERTANCE TUBE BY EXPERIMENTAL AND CFD METHODS

    SciTech Connect

    Chen Houlei; Zhao Miguang; Yang Luwei; Cai Jinghui; Hong Guotong; Liang Jingtao

    2010-04-09

    To investigate the oscillating gas flow along an inertance tube used in pulse tube coolers, a CFD model is set up for FLUENT and an experimental measuring cell is designed and optimized by CFD results. Some characteristics of oscillating flow are demonstrated and discussed. Then, the flow status along an inertance tube is measured by the optimized measuring cell. The experimental results validate the simulating results.

  8. Viscous shock layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous shock layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially symmetric flow fields. Solutions are obtained using an implicit finite difference scheme and results are presented for hypersonic flow over spherically blunted cone configurations at free stream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  9. Viscous-shock-layer solutions for turbulent flow of radiating gas mixtures in chemical equilibrium

    NASA Technical Reports Server (NTRS)

    Anderson, E. C.; Moss, J. N.

    1975-01-01

    The viscous-shock-layer equations for hypersonic laminar and turbulent flows of radiating or nonradiating gas mixtures in chemical equilibrium are presented for two-dimensional and axially-symmetric flow fields. Solutions were obtained using an implicit finite-difference scheme and results are presented for hypersonic flow over spherically-blunted cone configurations at freestream conditions representative of entry into the atmosphere of Venus. These data are compared with solutions obtained using other methods of analysis.

  10. Numerical simulations of natural gas flow in pipe system with flowmeters

    NASA Astrophysics Data System (ADS)

    Kňourek, Jindřich; Matas, Richard; Prokeš, Ondřej; Tenkrát, Daniel

    2014-03-01

    Numerical simulation of the flow behavior in part of large pipe system is presented in this article. Compressed natural gas is transported through the system in a dynamic unsteady way. Velocities at several points and velocity profiles at certain positions are monitored during the numerical simulation. The aim is to investigate the stability of velocity profiles at the positions of flowmeters in course of flow time. In addition, the possibility of flow conditioning in the system is presented and discussed.

  11. Gas flow environmental and heat transfer nonrotating 3D program

    NASA Technical Reports Server (NTRS)

    Geil, T.; Steinhoff, J.

    1983-01-01

    A complete set of benchmark quality data for the flow and heat transfer within a large rectangular turning duct is being compiled. These data will be used to evaluate and verify three dimensional internal viscous flow models and computational codes. The analytical objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated.

  12. Multicomponent gas flow computations by a discontinuous Galerkin scheme using L2-projection of perfect gas EOS

    NASA Astrophysics Data System (ADS)

    Franchina, N.; Savini, M.; Bassi, F.

    2016-06-01

    A new formulation of multicomponent gas flow computation, suited to a discontinuous Galerkin discretization, is here presented and discussed. The original key feature is the use of L2-projection form of the (perfect gas) equation of state that allows all thermodynamic variables to span the same functional space. This choice greatly mitigates problems encountered by the front-capturing schemes in computing discontinuous flow field, retaining at the same time their conservation properties at the discrete level and ease of use. This new approach, combined with an original residual-based artificial dissipation technique, shows itself capable, through a series of tests illustrated in the paper, to both control the spurious oscillations of flow variables occurring in high-order accurate computations and reduce them increasing the degree of the polynomial representation of the solution. This result is of great importance in computing reacting gaseous flows, where the local accuracy of temperature and species mass fractions is crucial to the correct evaluation of the chemical source terms contained in the equations, even if the presence of the physical diffusivities somewhat brings relief to these problems. The present work can therefore also be considered, among many others already presented in the literature, as the authors' first step toward the construction of a new discontinuous Galerkin scheme for reacting gas mixture flows.

  13. Simulation of rarefied gas flows in atmospheric pressure interfaces for mass spectrometry systems.

    PubMed

    Garimella, Sandilya; Zhou, Xiaoyu; Ouyang, Zheng

    2013-12-01

    The understanding of the gas dynamics of the atmospheric pressure interface is very important for the development of mass spectrometry systems with high sensitivity. While the gas flows at high pressure (>1 Torr) and low pressure (<10(-3) Torr) stages are relatively well understood and could be modeled using continuum and molecular flows, respectively, the theoretical modeling or numeric simulation of gas flow through the transition pressure stage (1 to 10(-3) Torr) remains challenging. In this study, we used the direct simulation Monte Carlo (DMSC) method to develop the gas dynamic simulations for the continuous and discontinuous atmospheric pressure interfaces (API), with different focuses on the ion transfer by gas flows through a skimmer or directly from the atmospheric pressure to a vacuum stage, respectively. The impacts by the skimmer location in the continuous API and the temporal evolvement of the gas flow with a discontinuous API were characterized, which provide a solid base for the instrument design and performance improvement.

  14. Heat transfer between a stationary granular packing and a descending flow of dusty gas

    SciTech Connect

    Dryabin, V.A.; Galershtein, D.M.

    1988-10-01

    The transfer of heat from a stationary granular bed (packing) to a gas-particle flow has been investigated experimentally. Heat transfer experiments were carried out on an apparatus with an open gas-particle flow system. Monodisperse packing comprised of smooth steel balls or round porcelain granules was used. Particles used in the gas flow consisted of grades of sand and electrical corundum. The external heat transfer coefficient was determined by local modeling of heat transfer in the steady temperature field regime. Calorimetry was used for determining this regime as well as the temperature of the air and dusty gas. A correlation was obtained for calculating the heat-transfer coefficient in the system.

  15. Reacting Multi-Species Gas Capability for USM3D Flow Solver

    NASA Technical Reports Server (NTRS)

    Frink, Neal T.; Schuster, David M.

    2012-01-01

    The USM3D Navier-Stokes flow solver contributed heavily to the NASA Constellation Project (CxP) as a highly productive computational tool for generating the aerodynamic databases for the Ares I and V launch vehicles and Orion launch abort vehicle (LAV). USM3D is currently limited to ideal-gas flows, which are not adequate for modeling the chemistry or temperature effects of hot-gas jet flows. This task was initiated to create an efficient implementation of multi-species gas and equilibrium chemistry into the USM3D code to improve its predictive capabilities for hot jet impingement effects. The goal of this NASA Engineering and Safety Center (NESC) assessment was to implement and validate a simulation capability to handle real-gas effects in the USM3D code. This document contains the outcome of the NESC assessment.

  16. Gas Flow Tightly Coupled to Elastoplastic Geomechanics for Tight- and Shale-Gas Reservoirs: Material Failure and Enhanced Permeability

    DOE PAGES

    Kim, Jihoon; Moridis, George J.

    2014-12-01

    We investigate coupled flow and geomechanics in gas production from extremely low permeability reservoirs such as tight and shale gas reservoirs, using dynamic porosity and permeability during numerical simulation. In particular, we take the intrinsic permeability as a step function of the status of material failure, and the permeability is updated every time step. We consider gas reservoirs with the vertical and horizontal primary fractures, employing the single and dynamic double porosity (dual continuum) models. We modify the multiple porosity constitutive relations for modeling the double porous continua for flow and geomechanics. The numerical results indicate that production of gasmore » causes redistribution of the effective stress fields, increasing the effective shear stress and resulting in plasticity. Shear failure occurs not only near the fracture tips but also away from the primary fractures, which indicates generation of secondary fractures. These secondary fractures increase the permeability significantly, and change the flow pattern, which in turn causes a change in distribution of geomechanical variables. From various numerical tests, we find that shear failure is enhanced by a large pressure drop at the production well, high Biot's coefficient, low frictional and dilation angles. Smaller spacing between the horizontal wells also contributes to faster secondary fracturing. When the dynamic double porosity model is used, we observe a faster evolution of the enhanced permeability areas than that obtained from the single porosity model, mainly due to a higher permeability of the fractures in the double porosity model. These complicated physics for stress sensitive reservoirs cannot properly be captured by the uncoupled or flow-only simulation, and thus tightly coupled flow and geomechanical models are highly recommended to accurately describe the reservoir behavior during gas production in tight and shale gas reservoirs and to smartly design

  17. Multiphase imaging of gas flow in a nanoporous material usingremote detection NMR

    SciTech Connect

    Harel, Elad; Granwehr, Josef; Seeley, Juliette A.; Pines, Alex

    2005-10-03

    Pore structure and connectivity determine how microstructured materials perform in applications such as catalysis, fluid storage and transport, filtering, or as reactors. We report a model study on silica aerogel using a recently introduced time-of-flight (TOF) magnetic resonance imaging technique to characterize the flow field and elucidate the effects of heterogeneities in the pore structure on gas flow and dispersion with Xe-129 as the gas-phase sensor. The observed chemical shift allows the separate visualization of unrestricted xenon and xenon confined in the pores of the aerogel. The asymmetrical nature of the dispersion pattern alludes to the existence of a stationary and a flow regime in the aerogel. An exchange time constant is determined to characterize the gas transfer between them. As a general methodology, this technique provides new insights into the dynamics of flow in porous media where multiple phases or chemical species may be present.

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

    SciTech Connect

    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 of riser flow and the characteristics of gas–solid jet were reasonably predicted compared with the experimental measurements made at NETL.

  19. Real-Gas Flow Properties for NASA Langley Research Center Aerothermodynamic Facilities Complex Wind Tunnels

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.

    1996-01-01

    A computational algorithm has been developed which can be employed to determine the flow properties of an arbitrary real (virial) gas in a wind tunnel. A multiple-coefficient virial gas equation of state and the assumption of isentropic flow are used to model the gas and to compute flow properties throughout the wind tunnel. This algorithm has been used to calculate flow properties for the wind tunnels of the Aerothermodynamics Facilities Complex at the NASA Langley Research Center, in which air, CF4. He, and N2 are employed as test gases. The algorithm is detailed in this paper and sample results are presented for each of the Aerothermodynamic Facilities Complex wind tunnels.

  20. Pore network modeling of two-phase flow in a liquid-(disconnected) gas system

    NASA Astrophysics Data System (ADS)

    Bravo, Maria C.; Araujo, Mariela; Lago, Marcelo E.

    2007-02-01

    The appropriate description of two-phase flow in some systems requires a detailed analysis of the fundamental equations of flow and transport including momentum transfer between fluid phases. In the particular case of two-phase flow of oil and gas through porous media, when the gas phase is present as disconnected bubbles, there are inconsistencies in calculated flow properties derived by using the conventional Darcean description. In a two-phase system, the motion of one fluid phase may induce significant changes in the mobility of the second phase, as known from the generalized transport equations derived by Whitaker and Kalaydjian. The relevance of such coupling coefficients with respect to the conventional relative permeability term in two-phase Darcean flow is evaluated in this work for an oil-(disconnected) gas system. The study was performed using a new Pore Network Simulator specially designed for this case. Results considering both, Darcy's equation and generalized flow equations suggest that the four transport coefficients (effective permeabilities and coupling coefficients) are needed for a proper description of the macroscopic flow in a liquid-disconnected gas system.

  1. Comparison of electrical capacitance tomography & gamma densitometer measurement in viscous oil-gas flows

    NASA Astrophysics Data System (ADS)

    Archibong Eso, A.; Zhao, Yabin; Yeung, Hoi

    2014-04-01

    Multiphase flow is a common occurrence in industries such as nuclear, process, oil & gas, food and chemical. A prior knowledge of its features and characteristics is essential in the design, control and management of such processes due to its complex nature. Electrical Capacitance Tomography (ECT) and Gamma Densitometer (Gamma) are two promising approaches for multiphase visualization and characterization in process industries. In two phase oil & gas flow, ECT and Gamma are used in multiphase flow monitoring techniques due to their inherent simplicity, robustness, and an ability to withstand wide range of operational temperatures and pressures. High viscous oil (viscosity > 100 cP) is of interest because of its huge reserves, technological advances in its production and unlike conventional oil (oil viscosity < 100 cP) and gas flows where ECT and Gamma have been previously used, high viscous oil and gas flows comes with certain associated concerns which include; increased entrainment of gas bubbles dispersed in oil, shorter and more frequent slugs as well as oil film coatings on the walls of flowing conduits. This study aims to determine the suitability of both devices in the visualization and characterization of high-viscous oil and gas flow. Static tests are performed with both devices and liquid holdup measurements are obtained. Dynamic experiments were also conducted in a 1 & 3 inch facility at Cranfield University with a range of nominal viscosities (1000, 3000 & 7500 cP). Plug, slug and wavy annular flow patterns were identified by means of Probability Mass Function and time series analysis of the data acquired from Gamma and ECT devices with high speed camera used to validate the results. Measured Liquid holdups for both devices were also compared.

  2. Comparison of electrical capacitance tomography and gamma densitometer measurement in viscous oil-gas flows

    SciTech Connect

    Archibong Eso, A.; Zhao, Yabin; Yeung, Hoi

    2014-04-11

    Multiphase flow is a common occurrence in industries such as nuclear, process, oil and gas, food and chemical. A prior knowledge of its features and characteristics is essential in the design, control and management of such processes due to its complex nature. Electrical Capacitance Tomography (ECT) and Gamma Densitometer (Gamma) are two promising approaches for multiphase visualization and characterization in process industries. In two phase oil and gas flow, ECT and Gamma are used in multiphase flow monitoring techniques due to their inherent simplicity, robustness, and an ability to withstand wide range of operational temperatures and pressures. High viscous oil (viscosity > 100 cP) is of interest because of its huge reserves, technological advances in its production and unlike conventional oil (oil viscosity < 100 cP) and gas flows where ECT and Gamma have been previously used, high viscous oil and gas flows comes with certain associated concerns which include; increased entrainment of gas bubbles dispersed in oil, shorter and more frequent slugs as well as oil film coatings on the walls of flowing conduits. This study aims to determine the suitability of both devices in the visualization and characterization of high-viscous oil and gas flow. Static tests are performed with both devices and liquid holdup measurements are obtained. Dynamic experiments were also conducted in a 1 and 3 inch facility at Cranfield University with a range of nominal viscosities (1000, 3000 and 7500 cP). Plug, slug and wavy annular flow patterns were identified by means of Probability Mass Function and time series analysis of the data acquired from Gamma and ECT devices with high speed camera used to validate the results. Measured Liquid holdups for both devices were also compared.

  3. Unsteady rarefied gas flow in a microchannel driven by a pressure difference

    NASA Astrophysics Data System (ADS)

    Konopel'ko, N. A.; Titarev, V. A.; Shakhov, E. M.

    2016-03-01

    The kinetic S-model is used to study the unsteady rarefied gas flow through a plane channel between two parallel infinite plates. Initially, the gas is at rest and is separated by the plane x = 0 with different pressure values on opposite sides. The gas deceleration effect of the channel walls is studied depending on the degree of gas rarefaction and the initial pressure drop, assuming that the molecules are diffusely reflected from the boundary. The decay of the shock wave and the disappearance of the uniform flow region behind the shock wave are monitored. Special attention is given to the gas mass flux through the cross section at x = 0, which is computed as a function of time. The asymptotic behavior of the solution at unboundedly increasing time is analyzed. The kinetic equation is solved numerically by applying a conservative finite-difference method of second-order accuracy in space.

  4. Real-Gas Correction Factors for Hypersonic Flow Parameters in Helium

    NASA Technical Reports Server (NTRS)

    Erickson, Wayne D.

    1960-01-01

    The real-gas hypersonic flow parameters for helium have been calculated for stagnation temperatures from 0 F to 600 F and stagnation pressures up to 6,000 pounds per square inch absolute. The results of these calculations are presented in the form of simple correction factors which must be applied to the tabulated ideal-gas parameters. It has been shown that the deviations from the ideal-gas law which exist at high pressures may cause a corresponding significant error in the hypersonic flow parameters when calculated as an ideal gas. For example the ratio of the free-stream static to stagnation pressure as calculated from the thermodynamic properties of helium for a stagnation temperature of 80 F and pressure of 4,000 pounds per square inch absolute was found to be approximately 13 percent greater than that determined from the ideal-gas tabulation with a specific heat ratio of 5/3.

  5. Combined mass and heat transfer during nonisothermal absorption in gas-liquid slug flow

    SciTech Connect

    Elperin, T.; Fominykh, A.

    1995-03-01

    A model of combined mass and heat transfer during nonisothermal gas absorption from a slug rising, in a channel filled with liquid is suggested. The expressions for coefficients of heat and mass transfer from a single slug are derived in the approximation of the thin concentration and heat boundary layers in a liquid phase. Under the assumptions of a perfect mixing of the dissolved -as in liquid plugs and uniform temperature distribution in liquid plugs, recurrent relations for the dissolved gas concentration and temperature in the n-th liquid plug and mass and heat fluxes from the n-th gas slug are derived. The total mass and heat fluxes in a gas-liquid slug flow are determined. In the limiting case of absorption without heat release the derived formulas recover the expressions for isothermal absorption in a gas-liquid slug flow.

  6. DEVELOPMENT OF A LOW-COST INFERENTIAL NATURAL GAS ENERGY FLOW RATE PROTOTYPE RETROFIT MODULE

    SciTech Connect

    E. Kelner; T.E. Owen; D.L. George; A. Minachi; M.G. Nored; C.J. Schwartz

    2004-03-01

    In 1998, Southwest Research Institute{reg_sign} began a multi-year project co-funded by the Gas Research Institute (GRI) and the U.S. Department of Energy. The project goal is to develop a working prototype instrument module for natural gas energy measurement. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype retrofit natural gas energy flow meter in 2000-2001 included: (1) evaluation of the inferential gas energy analysis algorithm using supplemental gas databases and anticipated worst-case gas mixtures; (2) identification and feasibility review of potential sensing technologies for nitrogen diluent content; (3) experimental performance evaluation of infrared absorption sensors for carbon dioxide diluent content; and (4) procurement of a custom ultrasonic transducer and redesign of the ultrasonic pulse reflection correlation sensor for precision speed-of-sound measurements. A prototype energy meter module containing improved carbon dioxide and speed-of-sound sensors was constructed and tested in the GRI Metering Research Facility at SwRI. Performance of this module using transmission-quality natural gas and gas containing supplemental carbon dioxide up to 9 mol% resulted in gas energy determinations well within the inferential algorithm worst-case tolerance of {+-}2.4 Btu/scf (nitrogen diluent gas measured by gas chromatograph). A two-week field test was performed at a gas-fired power plant to evaluate the inferential algorithm and the data acquisition requirements needed to adapt the prototype energy meter module to practical field site conditions.

  7. Gas flow models in the Milky Way embedded bars

    NASA Astrophysics Data System (ADS)

    Rodriguez-Fernandez, N. J.; Combes, F.

    2008-10-01

    Context: The gas distribution and dynamics in the inner Galaxy present many unknowns, such as the origin of the asymmetry of the lv-diagram of the Central Molecular Zone (CMZ). On the other hand, there is recent evidence in the stellar component of the presence of a nuclear bar that may be slightly lopsided. Aims: Our goal is to characterize the nuclear bar observed in 2MASS maps and to study the gas dynamics in the inner Milky Way taking into account this secondary bar. Methods: We have derived a realistic mass distribution by fitting the 2MASS star count map with a model including three components (disk, bulge and nuclear bar) and we have simulated the gas dynamics in the deduced gravitational potential using a sticky-particles code. Results: Our simulations of the gas dynamics successfully reproduce the main characteristics of the Milky Way for a bulge orientation of 20°-35°with respect to the Sun-Galactic Center (GC) line and a pattern speed of 30-40 km s-1 kpc-1. In our models the Galactic Molecular Ring (GMR) is not an actual ring but the inner parts of the spiral arms, while the 3-kpc arm and its far side counterpart are lateral arms that extend around the bar. Our simulations reproduce, for the first time, the parallelogram shape of the lv-diagram of the CMZ as the gas response to the nuclear bar. This bar should be oriented by an angle of ˜60°-75°with respect to the Sun-GC line and its mass amounts to (2-5.5) 109 M_⊙. We show that the observed asymmetry of the CMZ cannot be due to lopsidedness of the nuclear bar as suggested by the 2MASS maps. Conclusions: We do not find clear evidence of lopsidedness in the stellar potential. We propose that the observed asymmetry of the central gas layer can be due to the infalling of gas into the CMZ in the l = 1.3°-complex. Tables 3-6 are only available in electronic form at http://www.aanda.org

  8. Gas flow environmental and heat transfer nonrotating 3D program

    NASA Technical Reports Server (NTRS)

    Crawford, R. A.

    1984-01-01

    The experimental contract objective is to provide a complete set of benchmark quality data for the flow within a large rectangular turning duct. The data are to be used to evaluate and verify three-dimensional internal viscous flow models and computational codes. The analytical contract objective is to select such a computational code and define the capabilities of this code to predict the experimental results. Details of the proper code operation will be defined and improvements to the code modeling capabilities will be formulated.

  9. The Influence of Shielding Gas Flow Rate on the Transfer Frequency of Electrode Metals Drops

    NASA Astrophysics Data System (ADS)

    Chinakhov, D. A.; Grigorieva, E. G.; Mayorova, E. I.; Kartsev, D. S.

    2016-08-01

    Chemical composition of weld metal and properties of a joint weld are dominated by the processes occurring in the drop of molten electrode metal and in metal of the weld pool. Under certain conditions in consumable electrode welding with jet gas shielding the drop of electrode metal is influenced significantly both by main forces and the force of gas-dynamic impact of the shielding gas jet. The results of research have revealed that changing rate of shielding gas flow on the nozzle section influences the processes taking place in the welding area. There are changes in the transfer frequency of electrode metal drops and chemical composition of weld metal.

  10. 76 FR 72666 - Pipeline Safety: Expanding the Use of Excess Flow Valves in Gas Distribution Systems to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-25

    ...: Expanding the Use of Excess Flow Valves in Gas Distribution Systems to Applications Other Than Single-Family... several issues relating to the expanded use of excess flow valves (EFVs) in gas distribution systems.... Operators of gas distribution systems can also expand the use of EFVs to applications other than...

  11. Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

    PubMed

    Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

    2016-02-01

    We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested

  12. Transport Phenomena of Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C. H.; Lehoczky, S. L.; Zhang, S.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Various high quality epitaxial films, especially oxides, have been synthesized using off-axis sputtering deposition. In this presentation, we report the experiment results of ZnO films grown by the off-axis sputtering deposition. Films were synthesized in temperatures ranged from room temperature to 600 C, and pressures from 5 mTorr to 150 mTorr. Film growth rate was measured by surface profilometer, ellipsometer, and wavelength dispersive spectrometry. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement for low pressure to a diffuse drift for high pressure in which the transport species were almost thermalized. The measurements show an increase of growth rates along the gravity vector when the Knodson (Knudsen??) number of transport species is less than 0.05, which suggests that gravity affected the transport characterization in off-axis sputtering deposition. Because the product of pressure (p) and travel distance (d) of sputtered species, p exceeds several mTorr-cm during film deposition, the classical simulations for sputtering process in high vacuum system may not be applied. Based on these experimental measurements, a transport process of the off-axis sputtering deposition is proposed. Several methods including the Monte Carlo method and gravity-driven flow dynamics simulation will be discussed.

  13. Fictitious domain method for fully resolved reacting gas-solid flow simulation

    NASA Astrophysics Data System (ADS)

    Zhang, Longhui; Liu, Kai; You, Changfu

    2015-10-01

    Fully resolved simulation (FRS) for gas-solid multiphase flow considers solid objects as finite sized regions in flow fields and their behaviours are predicted by solving equations in both fluid and solid regions directly. Fixed mesh numerical methods, such as fictitious domain method, are preferred in solving FRS problems and have been widely researched. However, for reacting gas-solid flows no suitable fictitious domain numerical method has been developed. This work presents a new fictitious domain finite element method for FRS of reacting particulate flows. Low Mach number reacting flow governing equations are solved sequentially on a regular background mesh. Particles are immersed in the mesh and driven by their surface forces and torques integrated on immersed interfaces. Additional treatments on energy and surface reactions are developed. Several numerical test cases validated the method and a burning carbon particles array falling simulation proved the capability for solving moving reacting particle cluster problems.

  14. A study of pneumatic conveying of gas-solid flow for industrial application

    NASA Astrophysics Data System (ADS)

    Al-Khateeb, Khalid A. S.; Tasnim, Rumana; Khan, Sheroz; Mohammod, Musse; Arshad, Atika; Shobaki, Mohammed M.; Haider, Samnan; Saquib, Nazmus; Rahman, Tawfilur

    2013-12-01

    The complicated nature of gas-solids' physical properties have challenged the researchers over past decades who have led their efforts in developing its' flow sensing and measurement methods. The term 'gas-solid flow' signifies dilute- or dense-phase flow with a very little concentration of solids. For conducting such flow measurement, generally velocity profile and volumetric concentration of the flow particles being conveyed are needed to be measured. An important application of gas-solid flow has taken root in the form of biomass flow in pneumatic conveying systems, and its' online measurement has proven to be an exigent research pursuit. Additionally the other applications have been explored in power plants, food, chemical and automobiles industries as well. This paper aims at exploring the evolution of flow measurement methods along with a brief explanation on existing fundamental sensing techniques. Furthermore, the most recent patents developed for such measurements in pneumatic conveying pipelines are scrutinized along with their concomitant pros and cons.

  15. Flow chemistry: intelligent processing of gas-liquid transformations using a tube-in-tube reactor.

    PubMed

    Brzozowski, Martin; O'Brien, Matthew; Ley, Steven V; Polyzos, Anastasios

    2015-02-17

    CONSPECTUS: The previous decade has witnessed the expeditious uptake of flow chemistry techniques in modern synthesis laboratories, and flow-based chemistry is poised to significantly impact our approach to chemical preparation. The advantages of moving from classical batch synthesis to flow mode, in order to address the limitations of traditional approaches, particularly within the context of organic synthesis are now well established. Flow chemistry methodology has led to measurable improvements in safety and reduced energy consumption and has enabled the expansion of available reaction conditions. Contributions from our own laboratories have focused on the establishment of flow chemistry methods to address challenges associated with the assembly of complex targets through the development of multistep methods employing supported reagents and in-line monitoring of reaction intermediates to ensure the delivery of high quality target compounds. Recently, flow chemistry approaches have addressed the challenges associated with reactions utilizing reactive gases in classical batch synthesis. The small volumes of microreactors ameliorate the hazards of high-pressure gas reactions and enable improved mixing with the liquid phase. Established strategies for gas-liquid reactions in flow have relied on plug-flow (or segmented flow) regimes in which the gas plugs are introduced to a liquid stream and dissolution of gas relies on interfacial contact of the gas bubble with the liquid phase. This approach confers limited control over gas concentration within the liquid phase and is unsuitable for multistep methods requiring heterogeneous catalysis or solid supported reagents. We have identified the use of a gas-permeable fluoropolymer, Teflon AF-2400, as a simple method of achieving efficient gas-liquid contact to afford homogeneous solutions of reactive gases in flow. The membrane permits the transport of a wide range of gases with significant control of the stoichiometry of

  16. TVENT1P. Gas-Dynamic Transients Flow Networks

    SciTech Connect

    Eyberger, L.

    1987-09-01

    TVENT1P predicts flows and pressures in a ventilation system or other air pathway caused by pressure transients, such as a tornado. For an analytical model to simulate an actual system, it must have (1) the same arrangement of components in a network of flow paths; (2) the same friction characteristics; (3) the same boundary pressures; (4) the same capacitance; and (5) the same forces that drive the air. A specific set of components used for constructing the analytical model includes filters, dampers, ducts, blowers, rooms, or volume connected at nodal points to form networks. The effects of a number of similar components can be lumped into a single one. TVENT1P contains a material transport algorithm and features for turning blowers off and on, changing blower speeds, changing the resistance of dampers and filters, and providing a filter model to handle very high flows. These features make it possible to depict a sequence of events during a single run. Component properties are varied using time functions. The filter model is not used by the code unless it is specified by the user. The basic results of a TVENT1P solution are flows in branches and pressures at nodes. A postprocessor program, PLTTEX, is included to produce the plots specified in the TVENT1P input. PLTTEX uses the proprietary CA-DISSPLA graphics software.

  17. Particle-wave duality and coherent instability control in dense gas-solid flows.

    SciTech Connect

    Li, J.; Liu, Y. Y.; Decision and Information Sciences

    2008-02-01

    The collective effect of transport behaviors in a multibody system can either drastically enhance or deteriorate system performance depending on the nature of the internal interactions (i.e., constructive or deconstructive) and the structure established. For most powder processes, flow instability leads to poor performance. Control strategies have been attempted previously, but with limited success. The ability to drive such a system that is far from equilibrium into its 'ordered' state by tuning the interactions can effectively reduce internal energy dissipation, which may lead to a technological breakthrough. By using a hybrid dynamics simulation and multiphase flow experiments, we will first elucidate two fundamental mechanisms underlying flow instabilities in a dense gas-solid flow: nonlinear drag and collisional dissipation. Then we clarify how gas-fluidized particles exhibit 'particle-wave' duality (e.g., exhibit standing waves in a thin layer of granular bed that are driven by superimposed oscillating air, when the exciting frequencies of the oscillating air match the system's natural frequency). On this basis, we show experimentally that dense gas-fluidized granules can be synchronized into 'ordered' structures by developing an adaptively exciting fluid wave. The introduction of an additional fluid wave enables the flow structures to be fine-tuned. Our method results in remarkably improved fluidization: highly expanded particulate beds with significantly suppressed gas bubble formation (for coarse particles) and channel formation (for ultra-fine powders), as has always prevailed in conventional dense gas-particle systems. By applying our methodology to several systems that are normally difficult to fluidize, we achieve unprecedented, well-controlled suspension of solids in gas flow. A scientific understanding of complex, dense gas-solid flows should enable the dispersion of solids in the gas flow to be controlled effectively. This work contributes to the

  18. Synthesis of α-MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin films and their application in gas sensing

    NASA Astrophysics Data System (ADS)

    Dwivedi, Priyanka; Dhanekar, Saakshi; Das, Samaresh

    2016-11-01

    Synthesis of orthorhombic (α) MoO3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented. The influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy. A structural study shows that MoO3 is polycrystalline in nature with an α phase. It was noticed that oxidation temperature plays an important role in the formation of nano-flakes. The synthesis technique proposed is simple and suitable for large scale productions. The synthesis parameters were optimized for the fabrication of sensors. Chrome gold-based IDE (interdigitated electrodes) structures were patterned for the electrical detection of organic vapors. Sensors were exposed to wide range 5–100 ppm of organic vapors like ethanol, acetone, IPA (isopropanol alcohol) and water vapors. α-MoO3 nano-flakes have demonstrated selective sensing to acetone in the range of 10–100 ppm at 150 °C. The morphology of such nanostructures has potential in applications such as sensor devices due to their high surface area and thermal stability.

  19. Modeling study of rarefied gas effects on hypersonic reacting stagnation flows

    NASA Astrophysics Data System (ADS)

    Wang, Zhihui; Bao, Lin

    2014-12-01

    Recent development of the near space hypersonic sharp leading vehicles has raised a necessity to fast and accurately predict the aeroheating in hypersonic rarefied flows, which challenges our understanding of the aerothermodynamics and aerothermochemistry. The present flow and heat transfer problem involves complex rarefied gas effects and nonequilibrium real gas effects which are beyond the scope of the traditional prediction theory based on the continuum hypothesis and equilibrium assumption. As a typical example, it has been found that the classical Fay-Riddell equation fails to predict the stagnation point heat flux, when the flow is either rarefied or chemical nonequilibrium. In order to design a more general theory covering the rarefied reacting flow cases, an intuitive model is proposed in this paper to describe the nonequilibrium dissociation-recombination flow along the stagnation streamline towards a slightly blunted nose in hypersonic rarefied flows. Some characteristic flow parameters are introduced, and based on these parameters, an explicitly analytical bridging function is established to correct the traditional theory to accurately predict the actual aeroheating performance. It is shown that for a small size nose in medium density flows, the flow at the outer edge of the stagnation point boundary layer could be highly nonequilibrium, and the aeroheating performance is distinguished from that of the big blunt body reentry flows at high altitudes. As a result, when the rarefied gas effects and the nonequilibrium real gas effects are both significant, the classical similarity law could be questionable, and it is inadequate to directly analogize results from the classical blunt body reentry problems to the present new generation sharp-leading vehicles. In addition, the direct simulation Monte Carlo method is also employed to validate the conclusion.

  20. Investigation of a New Monte Carlo Method for the Transitional Gas Flow

    SciTech Connect

    Luo, X.; Day, Chr.

    2011-05-20

    The Direct Simulation Monte Carlo method (DSMC) is well developed for rarefied gas flow in transition flow regime when 0.0110, the gas flow is free molecular and can be simulated by the Test Particle Monte Carlo method (TPMC) without any problem even for a complex 3D vacuum system. In this paper we will investigate the approach to extend the TPMC to the transition flow regime by considering the collision between gas molecules as an interaction between a probe molecule and the gas background. Recently this collision mechanism has been implemented into ProVac3D, a new TPMC simulation program developed by Karlsruhe Institute of Technology (KIT). The preliminary simulation result shows a correct nonlinear increasing of the gas flow. However, there is still a quantitative discrepancy with the experimental data, which means further improvement is needed.

  1. 2D models of gas flow and ice grain acceleration in Enceladus' vents using DSMC methods

    NASA Astrophysics Data System (ADS)

    Tucker, Orenthal J.; Combi, Michael R.; Tenishev, Valeriy M.

    2015-09-01

    The gas distribution of the Enceladus water vapor plume and the terminal speeds of ejected ice grains are physically linked to its subsurface fissures and vents. It is estimated that the gas exits the fissures with speeds of ∼300-1000 m/s, while the micron-sized grains are ejected with speeds comparable to the escape speed (Schmidt, J. et al. [2008]. Nature 451, 685-688). We investigated the effects of isolated axisymmetric vent geometries on subsurface gas distributions, and in turn, the effects of gas drag on grain acceleration. Subsurface gas flows were modeled using a collision-limiter Direct Simulation Monte Carlo (DSMC) technique in order to consider a broad range of flow regimes (Bird, G. [1994]. Molecular Gas Dynamics and the Direct Simulation of Gas Flows. Oxford University Press, Oxford; Titov, E.V. et al. [2008]. J. Propul. Power 24(2), 311-321). The resulting DSMC gas distributions were used to determine the drag force for the integration of ice grain trajectories in a test particle model. Simulations were performed for diffuse flows in wide channels (Reynolds number ∼10-250) and dense flows in narrow tubular channels (Reynolds number ∼106). We compared gas properties like bulk speed and temperature, and the terminal grain speeds obtained at the vent exit with inferred values for the plume from Cassini data. In the simulations of wide fissures with dimensions similar to that of the Tiger Stripes the resulting subsurface gas densities of ∼1014-1020 m-3 were not sufficient to accelerate even micron-sized ice grains to the Enceladus escape speed. In the simulations of narrow tubular vents with radii of ∼10 m, the much denser flows with number densities of 1021-1023 m-3 accelerated micron-sized grains to bulk gas speed of ∼600 m/s. Further investigations are required to understand the complex relationship between the vent geometry, gas source rate and the sizes and speeds of ejected grains.

  2. CFD Validation of Gas Injection in Flowing Mercury over Vertical Smooth and Grooved Wall

    SciTech Connect

    Abdou, Ashraf A; Wendel, Mark W; Felde, David K; Riemer, Bernie

    2009-01-01

    The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL).The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid mercury which produces high pressure waves. When these pressure waves hit the target vessel wall, cavitation can occur and erode the wall. Research and development efforts at SNS include creation of a vertical protective gas layer between the flowing liquid mercury and target vessel wall to mitigate the cavitation damage erosion and extend the life time of the target. Since mercury is opaque, computational fluid dynamics (CFD) can be used as a diagnostic tool to see inside the liquid mercury and guide the experimental efforts. In this study, CFD simulations of three dimensional, unsteady, turbulent, two-phase flow of helium gas injection in flowing liquid mercury over smooth, vertically grooved and horizontally grooved walls are carried out with the commercially available CFD code Fluent-12 from ANSYS. The Volume of Fluid (VOF) model is used to track the helium-mercury interface. V-shaped vertical and horizontal grooves with 0.5 mm pitch and about 0.7 mm depth were machined in the transparent wall of acrylic test sections. Flow visualization data of helium gas coverage through transparent test sections is obtained with a high-speed camera at the ORNL target test facility (TTF). The helium gas mass flow rate is 8 mg/min and introduced through a 0.5 mm diameter port. The local mercury velocity is 0.9 m/s. In this paper, the helium gas flow rate and the local mercury velocity are kept constant for the three cases. Time integration of predicted helium gas volume fraction over time is done to evaluate the gas coverage and calculate the average thickness of the helium gas layer. The predicted time-integrated gas coverage over vertically grooved and horizontally grooved test sections is better than over a smooth wall. The

  3. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  4. IR Ellipsometry on RF sputtered Permalloy Oxide thin films

    NASA Astrophysics Data System (ADS)

    Cui, Yubo; Geerts, Wilhelmus; Twagirayezu, Fidele; Zollner, Stefan

    2015-03-01

    Recently several electronic devices have achieved significant enhancements that have been attributed to an oxidized NiFe layer. A study on lateral spin valves, was found to have an increased magnetoresistance after leaving it exposed to air. The enhancements were attributed to the partly oxidation of a NiFe layer. Even more recently the turn on voltages of Hematite based water splitting devices was lowered to record low of .61 V with the addition of an amorphous NiFeOx layer. We investigated the optical properties of Ni80Fe20-oxide thin films that were deposited by reactive RF sputtering on quartz and Si/SiO2 substrates. Deposition was performed in an AJA Magnetron System using an Ar gas flow of 8 sccm and an oxygen gas flow of 2 sccm for different substrate temperatures (24-600 degrees Celsius). The optical properties in the visible spectrum and the film thickness were measured using a Woollam M2000 variable angle spectroscopic ellipsometer. Additional measurements were performed with a Woollam IR-VASE from 1.7 to 30 micrometer. The measurement results show the existence of a phonon peak around 382 cm-1 slightly red-shifted from the 390 cm-1 phonon peak of single crystalline NiO. XRD spectra did only reveal X-ray peaks of the rocksalt structure. This work was partly funded by National Science Foundation (DMR-1104934). Use of the facilities of the CINT at Sandia National Lab is acknowledged.

  5. Ground Based Studies of Gas-Liquid Flows in Microgravity Using Learjet Trajectories

    NASA Technical Reports Server (NTRS)

    Bousman, W. S.; Dukler, A. E.

    1994-01-01

    A 1.27 cm diameter two phase gas-liquid flow experiment has been developed with the NASA Lewis Research Center to study two-phase flows in microgravity. The experiment allows for the measurement of void fraction, pressure drop, film thickness and bubble and wave velocities as well as for high speed photography. Three liquids were used to study the effects of liquid viscosity and surface tension, and flow pattern maps are presented for each. The experimental results are used to develop mechanistically based models to predict void fraction, bubble velocity, pressure drop and flow pattern transitions in microgravity.

  6. On the Motion of an Annular Film in Microgravity Gas-Liquid Flow

    NASA Technical Reports Server (NTRS)

    McQuillen, John B.

    2002-01-01

    Three flow regimes have been identified for gas-liquid flow in a microgravity environment: Bubble, Slug, and Annular. For the slug and annular flow regimes, the behavior observed in vertical upflow in normal gravity is similar to microgravity flow with a thin, symmetrical annular film wetting the tube wall. However, the motion and behavior of this film is significantly different between the normal and low gravity cases. Specifically, the liquid film will slow and come to a stop during low frequency wave motion or slugging. In normal gravity vertical upflow, the film has been observed to slow, stop, and actually reverse direction until it meets the next slug or wave.

  7. Heterogeneous physical and chemical processes in a rarefied-gas flow in channels

    NASA Astrophysics Data System (ADS)

    Rebrov, A. K.; Yudin, I. B.

    2016-05-01

    A flow with physical and chemical reactions on hot surfaces is investigated. On the basis of physical experiments, determining the hydrogen-dissociation degree in rarefied gas and calculation of the flow by the method of direct simulation Monte Carlo (DSMC), it is possible to specify certain unknown constants of interaction of molecules and atoms with a tungsten surface. By the example of the hydrogen flow in a hightemperature tungsten cylindrical channel, the role of dissociation, sorption, and recombination processes is shown in a wide range of flow regimes from free-molecular to continuum.

  8. Comparative study of various approaches for modeling transitional hypersonic rarefied gas flows over blunt bodies

    NASA Astrophysics Data System (ADS)

    Brykina, I. G.; Rogov, B. V.; Tirskiy, G. A.; Titarev, V. A.; Utyuzhnikov, S. V.

    2012-11-01

    The hypersonic rarefied gas flow over blunt bodies in the transitional flow regime, typical of the reentry flight of space vehicles at altitudes higher 90-100 km, is investigated. As an example, the problem of hypersonic flows over long blunt wings and axisymmetric bodies is considered. It is analyzed in a wide range of the free stream Knudsen number by using various approaches: the continuum approach - numerical and analytical solutions, the direct simulation Monte Carlo method and the direct numerical solution of the Boltzmann kinetic equation with the S-model collision integral. The efficiency, domain of applicability, advantages and disadvantages of various approaches in the transitional flow regime are considered.

  9. Deposition of reactively ion beam sputtered silicon nitride coatings

    NASA Technical Reports Server (NTRS)

    Grill, A.

    1982-01-01

    An ion beam source was used to deposit silicon nitride films by reactively sputtering a silicon target with beams of Ar + N2 mixtures. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 2 millionth torr. The ion beam current was 50 mA at 500 V. The composition of the deposited films was investigated by auger electron spectroscopy and the rate of deposition was determined by interferometry. A relatively low rate of deposition of about 2 nm. one-tenth min. was found. AES spectra of films obtained with nitrogen fractions higher than 0.50 were consistent with a silicon to nitrogen ratio corresponding to Si3N4. However the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.

  10. Thermal/Pyrolysis Gas Flow Analysis of Carbon Phenolic Material

    NASA Technical Reports Server (NTRS)

    Clayton, J. Louie

    2001-01-01

    Provided in this study are predicted in-depth temperature and pyrolysis gas pressure distributions for carbon phenolic materials that are externally heated with a laser source. Governing equations, numerical techniques and comparisons to measured temperature data are also presented. Surface thermochemical conditions were determined using the Aerotherm Chemical Equilibrium (ACE) program. Surface heating simulation used facility calibrated radiative and convective flux levels. Temperatures and pyrolysis gas pressures are predicted using an upgraded form of the SINDA/CMA program that was developed by NASA during the Solid Propulsion Integrity Program (SPIP). Multispecie mass balance, tracking of condensable vapors, high heat rate kinetics, real gas compressibility and reduced mixture viscosity's have been added to the algorithm. In general, surface and in-depth temperature comparisons are very good. Specie partial pressures calculations show that a saturated water-vapor mixture is the main contributor to peak in-depth total pressure. Further, for most of the cases studied, the water-vapor mixture is driven near the critical point and is believed to significantly increase the local heat capacity of the composite material. This phenomenon if not accounted for in analysis models may lead to an over prediction in temperature response in charring regions of the material.

  11. Investigations of Sputtered Ion Production

    NASA Astrophysics Data System (ADS)

    Schauer, Stephen Nicholai

    Secondary Ion Mass Spectrometry is based on sputtered ion emission. Although the sputtering process was observed over 100 years ago, the ion emission process is still not well understood. Ions are formed with a wide range of energies, charge states and multiplicities, and ionization efficiencies can vary by orders of magnitude, depending on the particular ion and the matrix from which it originates. A series of studies are presented here which examine ion production in several unusual areas in order to gain insight into the sputtered ion emission process. The energy of analyzed ions is usually limited to 125 eV or less. The range of the Cameca IMS-3f at Arizona State University has been extended to analyze ions with up to 4500 eV of initial kinetic energy. The use of high energy ions to eliminate cluster interferences has been developed as an analytical technique. Doubly-charged positive ions of Mg, Al and Si have been widely studied. Other doubley-charged ions have been almost ignored, mainly due to low signal intensity. Studies of doubly-charged ions of the fourth row elements are presented here. The energy distribution of these ions indicates that they are formed by an Auger process, commonly referred to as the kinetic emission process. Small gas phase doubly-charged negative ions are very rare. Reports of atomic doubly-charged negative ions have been disproved, or were unable to be confirmed. Large molecules or clusters are able to accommodate a double -negative charge, because of the large separation between the two electrons. Observations of small carbon cluster dianions are discussed. The oscillations in intensity give an indication of their structure and stability. Electron bombardment can also cause the emission of ions from surfaces. There is some controversy as to whether the ions are desorbed directly from the sample, or are desorbed as neutrals and ionized above the sample by interaction with the electron beam or secondary electrons. Measurements of

  12. Couette flow regimes with heat transfer in rarefied gas

    SciTech Connect

    Abramov, A. A. Butkovskii, A. V.

    2013-06-15

    Based on numerical solution of the Boltzmann equation by direct statistic simulation, the Couette flow with heat transfer is studied in a broad range of ratios of plate temperatures and Mach numbers of a moving plate. Flow regime classification by the form of the dependences of the energy flux and friction stress on the Knudsen number Kn is proposed. These dependences can be simultaneously monotonic and nonmonotonic and have maxima. Situations are possible in which the dependence of the energy flux transferred to a plate on Kn has a minimum, while the dependence of the friction stress is monotonic or even has a maximum. Also, regimes exist in which the dependence of the energy flux on Kn has a maximum, while the dependence of the friction stress is monotonic, and vice versa.

  13. Gas flow in plant microfluidic networks controlled by capillary valves.

    PubMed

    Capron, M; Tordjeman, Ph; Charru, F; Badel, E; Cochard, H

    2014-03-01

    The xylem vessels of trees constitute a model natural microfluidic system. In this work, we have studied the mechanism of air flow in the Populus xylem. The vessel microstructure was characterized by optical microscopy, transmission electronic microscopy (TEM), and atomic force microscopy (AFM) at different length scales. The xylem vessels have length ≈15 cm and diameter ≈20μm. Flow from one vessel to the next occurs through ∼102 pits, which are grouped together at the ends of the vessels. The pits contain a thin, porous pit membrane with a thickness of 310 nm. We have measured the Young's moduli of the vessel wall and of the pits (both water-saturated and after drying) by specific nanoindentation and nanoflexion experiments with AFM. We found that both the dried and water-saturated pit membranes have Young's modulus around 0.4 MPa, in agreement with values obtained by micromolding of pits deformed by an applied pressure difference. Air injection experiments reveal that air flows through the xylem vessels when the differential pressure across a sample is larger than a critical value ΔPc=1.8 MPa. In order to model the air flow rate for ΔP⩾ΔPc, we assumed the pit membrane to be a porous medium that is strained by the applied pressure difference. Water menisci in the pit pores play the role of capillary valves, which open at ΔP=ΔPc. From the point of view of the plant physiology, this work presents a basic understanding of the physics of bordered pits. PMID:24730949

  14. Gas flow in plant microfluidic networks controlled by capillary valves.

    PubMed

    Capron, M; Tordjeman, Ph; Charru, F; Badel, E; Cochard, H

    2014-03-01

    The xylem vessels of trees constitute a model natural microfluidic system. In this work, we have studied the mechanism of air flow in the Populus xylem. The vessel microstructure was characterized by optical microscopy, transmission electronic microscopy (TEM), and atomic force microscopy (AFM) at different length scales. The xylem vessels have length ≈15 cm and diameter ≈20μm. Flow from one vessel to the next occurs through ∼102 pits, which are grouped together at the ends of the vessels. The pits contain a thin, porous pit membrane with a thickness of 310 nm. We have measured the Young's moduli of the vessel wall and of the pits (both water-saturated and after drying) by specific nanoindentation and nanoflexion experiments with AFM. We found that both the dried and water-saturated pit membranes have Young's modulus around 0.4 MPa, in agreement with values obtained by micromolding of pits deformed by an applied pressure difference. Air injection experiments reveal that air flows through the xylem vessels when the differential pressure across a sample is larger than a critical value ΔPc=1.8 MPa. In order to model the air flow rate for ΔP⩾ΔPc, we assumed the pit membrane to be a porous medium that is strained by the applied pressure difference. Water menisci in the pit pores play the role of capillary valves, which open at ΔP=ΔPc. From the point of view of the plant physiology, this work presents a basic understanding of the physics of bordered pits.

  15. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  16. DEVELOPMENT AND VALIDATION OF A MULTIFIELD MODEL OF CHURN-TURBULENT GAS/LIQUID FLOWS

    SciTech Connect

    Elena A. Tselishcheva; Steven P. Antal; Michael Z. Podowski; Donna Post Guillen

    2009-07-01

    The accuracy of numerical predictions for gas/liquid two-phase flows using Computational Multiphase Fluid Dynamics (CMFD) methods strongly depends on the formulation of models governing the interaction between the continuous liquid field and bubbles of different sizes. The purpose of this paper is to develop, test and validate a multifield model of adiabatic gas/liquid flows at intermediate gas concentrations (e.g., churn-turbulent flow regime), in which multiple-size bubbles are divided into a specified number of groups, each representing a prescribed range of sizes. The proposed modeling concept uses transport equations for the continuous liquid field and for each bubble field. The overall model has been implemented in the NPHASE-CMFD computer code. The results of NPHASE-CMFD simulations have been validated against the experimental data from the TOPFLOW test facility. Also, a parametric analysis on the effect of various modeling assumptions has been performed.

  17. Self-Powered Triboelectric Micro Liquid/Gas Flow Sensor for Microfluidics.

    PubMed

    Chen, Jie; Guo, Hengyu; Zheng, Jiangeng; Huang, Yingzhou; Liu, Guanlin; Hu, Chenguo; Wang, Zhong Lin

    2016-08-23

    Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble via the capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor's detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system.

  18. Self-Powered Triboelectric Micro Liquid/Gas Flow Sensor for Microfluidics.

    PubMed

    Chen, Jie; Guo, Hengyu; Zheng, Jiangeng; Huang, Yingzhou; Liu, Guanlin; Hu, Chenguo; Wang, Zhong Lin

    2016-08-23

    Liquid and gas flow sensors are important components of the micro total analysis systems (μTAS) for modern analytical sciences. In this paper, we proposed a self-powered triboelectric microfluidic sensor (TMS) by utilizing the signals produced from the droplet/bubble via the capillary and the triboelectrification effects on the liquid/solid interface for real-time liquid and gas flow detection. By alternating capillary with different diameters, the sensor's detecting range and sensitivity can be adjusted. Both the relationship between the droplet/bubble and capillary size, and the output signal of the sensor are systematically studied. By demonstrating the monitoring of the transfusion process for a patient and the gas flow produced from an injector, it shows that TMS has a great potential in building a self-powered micro total analysis system. PMID:27490518

  19. The 3-D CFD modeling of gas turbine combustor-integral bleed flow interaction

    NASA Technical Reports Server (NTRS)

    Chen, D. Y.; Reynolds, R. S.

    1993-01-01

    An advanced 3-D Computational Fluid Dynamics (CFD) model was developed to analyze the flow interaction between a gas turbine combustor and an integral bleed plenum. In this model, the elliptic governing equations of continuity, momentum and the k-e turbulence model were solved on a boundary-fitted, curvilinear, orthogonal grid system. The model was first validated against test data from public literature and then applied to a gas turbine combustor with integral bleed. The model predictions agreed well with data from combustor rig testing. The model predictions also indicated strong flow interaction between the combustor and the integral bleed. Integral bleed flow distribution was found to have a great effect on the pressure distribution around the gas turbine combustor.

  20. Interplay of discharge and gas flow in atmospheric pressure plasma jets

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Yang, JingLong; He, Feng; Cao, Zexian

    2011-05-01

    Interplay of discharge and gas flow in the atmospheric pressure plasma jets generated with three different discharge modes [N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 106, 013308 (2009); N. Jiang, A. L. Ji, and Z. X. Cao, J. Appl. Phys. 108, 033302 (2010)] has been investigated by simultaneous photographing of both plasma plumes and gas flows in the ambient, with the former being visualized by using an optical schlieren system. Gas flow gains a forward momentum from discharge except for the case of overflow jets at smaller applied voltages. Larger applied voltage implies an elongated plasma jet only for single-electrode mode; for dielectric barrier discharge jet the plume length maximizes at a properly applied voltage. These findings can help understand the underlying processes, and are useful particularly for the economic operation of tiny helium plasma jets and jet arrays.

  1. Method For Enhanced Gas Monitoring In High Density Flow Streams

    DOEpatents

    Von Drasek, William A.; Mulderink, Kenneth A.; Marin, Ovidiu

    2005-09-13

    A method for conducting laser absorption measurements in high temperature process streams having high levels of particulate matter is disclosed. An impinger is positioned substantially parallel to a laser beam propagation path and at upstream position relative to the laser beam. Beam shielding pipes shield the beam from the surrounding environment. Measurement is conducted only in the gap between the two shielding pipes where the beam propagates through the process gas. The impinger facilitates reduced particle presence in the measurement beam, resulting in improved SNR (signal-to-noise) and improved sensitivity and dynamic range of the measurement.

  2. Heat transfer coefficients of dilute flowing gas-solids suspensions

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Heat transfer coefficients of air-glass, argon-glass, and argon-aluminum suspensions were measured in horizontal and vertical tubes. The glass, 21.6 and 36.0 micron diameter particles, was suspended at gas Reynolds numbers between 11,000 and 21,000 and loading ratios between 0 and 2.5. The presence of particles generally reduced the heat transfer coefficient. The circulation of aluminum powder in the 0.870 inch diameter closed loop system produced tenacious deposits on protuberances into the stream. In the vertical test section, the Nusselt number reduction was attributed to viscous sublayer thickening; in the horizontal test section to particle deposition.

  3. Accelerated gas-liquid visible light photoredox catalysis with continuous-flow photochemical microreactors.

    PubMed

    Straathof, Natan J W; Su, Yuanhai; Hessel, Volker; Noël, Timothy

    2016-01-01

    In this protocol, we describe the construction and use of an operationally simple photochemical microreactor for gas-liquid photoredox catalysis using visible light. The general procedure includes details on how to set up the microreactor appropriately with inlets for gaseous reagents and organic starting materials, and it includes examples of how to use it to achieve continuous-flow preparation of disulfides or trifluoromethylated heterocycles and thiols. The reported photomicroreactors are modular, inexpensive and can be prepared rapidly from commercially available parts within 1 h even by nonspecialists. Interestingly, typical reaction times of gas-liquid visible light photocatalytic reactions performed in microflow are lower (in the minute range) than comparable reactions performed as a batch process (in the hour range). This can be attributed to the improved irradiation efficiency of the reaction mixture and the enhanced gas-liquid mass transfer in the segmented gas-liquid flow regime. PMID:26633128

  4. Accelerated gas-liquid visible light photoredox catalysis with continuous-flow photochemical microreactors.

    PubMed

    Straathof, Natan J W; Su, Yuanhai; Hessel, Volker; Noël, Timothy

    2016-01-01

    In this protocol, we describe the construction and use of an operationally simple photochemical microreactor for gas-liquid photoredox catalysis using visible light. The general procedure includes details on how to set up the microreactor appropriately with inlets for gaseous reagents and organic starting materials, and it includes examples of how to use it to achieve continuous-flow preparation of disulfides or trifluoromethylated heterocycles and thiols. The reported photomicroreactors are modular, inexpensive and can be prepared rapidly from commercially available parts within 1 h even by nonspecialists. Interestingly, typical reaction times of gas-liquid visible light photocatalytic reactions performed in microflow are lower (in the minute range) than comparable reactions performed as a batch process (in the hour range). This can be attributed to the improved irradiation efficiency of the reaction mixture and the enhanced gas-liquid mass transfer in the segmented gas-liquid flow regime.

  5. Numerical Investigation of PLIF Gas Seeding for Hypersonic Boundary Layer Flows

    NASA Technical Reports Server (NTRS)

    Johanson, Craig T.; Danehy, Paul M.

    2012-01-01

    Numerical simulations of gas-seeding strategies required for planar laser-induced fluorescence (PLIF) in a Mach 10 air flow were performed. The work was performed to understand and quantify adverse effects associated with gas seeding and to compare different flow rates and different types of seed gas. The gas was injected through a slot near the leading edge of a flat plate wedge model used in NASA Langley Research Center's 31- Inch Mach 10 Air Tunnel facility. Nitric oxide, krypton, and iodine gases were simulated at various injection rates. Simulation results showing the deflection of the velocity field for each of the cases are presented. Streamwise distributions of velocity and concentration boundary layer thicknesses as well as vertical distributions of velocity, temperature, and mass distributions are presented for each of the cases. Relative merits of the different seeding strategies are discussed.

  6. Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    SciTech Connect

    Mikheyev, P A; Shepelenko, A A; Voronov, A I; Kupryaev, Nikolai V

    2002-01-31

    The production of atomic iodine for an oxygen - iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 {mu}m. Atomic iodine concentrations sufficient for the operation of an oxygen - iodine laser were obtained. The concentration of atomic iodine amounted to 3.6 x 10{sup 15} cm{sup -3} for a pressure of the carrying argon gas of 15 Torr. The discharge stabilisation by a vortex gas flow allowed the glow discharge to be sustained in a strongly electronegative halogen-containing gas mixture for pressures up to 20 Torr. (active media)

  7. Summary of 1988 WIPP (Waste Isolation Pilot Plant) Facility horizon gas flow measurements

    SciTech Connect

    Stormont, J.C.

    1990-11-01

    Numerous gas flow measurements have been made at the Waste Isolation Pilot Plant (WIPP) Facility horizon during 1988. All tests have been pressure decay or constant pressure tests from single boreholes drilled from the underground excavations. The test fluid has been nitrogen. The data have been interpreted as permeabilities and porosities by means of a transient numerical solution method. A closed-form steady-state approximation provides a reasonable order-of-magnitude permeability estimate. The effective resolution of the measurement system is less than 10{sup {minus}20} m{sup 2}. Results indicate that beyond 1 to 5 m from an excavation, the gas flow is very small and the corresponding permeability is below the system resolution. Within the first meter of an excavation, the interpreted permeabilities can be 5 orders of magnitude greater than the undisturbed or far-field permeability. The interpreted permeabilities in the region between the undisturbed region and the first meter from an excavation are in the range of 10{sup {minus}16} to 10{sup {minus}20} m{sup 2}. Measurable gas flow occurs to a greater depth into the roof above WIPP excavations of different sizes and ages than into the ribs and floor. The gas flows into the formation surrounding the smallest excavation tested are consistently lower than those at similar locations surrounding larger excavations of comparable age. Gas flow measured in the interbed layers near the WIPP excavations is highly variable. Generally, immediately above and below excavations, relatively large gas flow is measured in the interbed layers. These results are consistent with previous measurements and indicate a limited disturbed zone surrounding WIPP excavations. 31 refs., 99 figs., 5 tabs.

  8. Dynamic gas flow during plasma operation in TMX-U

    SciTech Connect

    Pickles, W.L.; Carter, M.R.; Clower, C.A.; Drake, R.P.; Hunt, A.L.; Simonen, T.C.; Turner, W.C.

    1982-11-12

    Control of the neutral density outside of the plasma radius is essential for proper operation of the various plasma configurations in TMX-U. TMX-U excess-beam, stream-gun, gas-box, and beam-reflux gases are pumped internally in regions defined by 73/sup 0/ Ti-gettered liners and warm Ti-gettered plasma liners. The array of fast and slow ion gauges - a large TMX-U diagnostic - has been used to measure the dynamic pressure in many of the liner-defined regions on three time scales. The natural divertor action, or plasma pump effect, of mirror plasmas has been measured using the ion gauge diagnostics on a fast time scale during operation of TMX-U with ECRH start-up. Routine operation of TMX-U is enhanced by the ability to verify the effectiveness of gettering and to locate leaks using pressure data collected on the two slow time scales. A computer code, DYNAVAC 6, which treats TMX-U as a set of conductance-coupled regions with pumping and sources in each region, has been used to successfully model the overall gas dynamics during all phases of TMX-U operation.

  9. Accuracy analysis of high-order lattice Boltzmann models for rarefied gas flows

    NASA Astrophysics Data System (ADS)

    Meng, Jianping; Zhang, Yonghao

    2011-02-01

    In this work, we have theoretically analyzed and numerically evaluated the accuracy of high-order lattice Boltzmann (LB) models for capturing non-equilibrium effects in rarefied gas flows. In the incompressible limit, the LB equation is shown to be able to reduce to the linearized Bhatnagar-Gross-Krook (BGK) equation. Therefore, when the same Gauss-Hermite quadrature is used, LB method closely resembles the discrete velocity method (DVM). In addition, the order of Hermite expansion for the equilibrium distribution function is found not to be directly correlated with the approximation order in terms of the Knudsen number to the BGK equation for incompressible flows. Meanwhile, we have numerically evaluated the LB models for a standing-shear-wave problem, which is designed specifically for assessing model accuracy by excluding the influence of gas molecule/surface interactions at wall boundaries. The numerical simulation results confirm that the high-order terms in the discrete equilibrium distribution function play a negligible role in capturing non-equilibrium effect for low-speed flows. By contrast, appropriate Gauss-Hermite quadrature has the most significant effect on whether LB models can describe the essential flow physics of rarefied gas accurately. Our simulation results, where the effect of wall/gas interactions is excluded, can lead to conclusion on the LB modeling capability that the models with higher-order quadratures provide more accurate results. For the same order Gauss-Hermite quadrature, the exact abscissae will also modestly influence numerical accuracy. Using the same Gauss-Hermite quadrature, the numerical results of both LB and DVM methods are in excellent agreement for flows across a broad range of the Knudsen numbers, which confirms that the LB simulation is similar to the DVM process. Therefore, LB method can offer flexible models suitable for simulating continuum flows at the Navier-Stokes level and rarefied gas flows at the linearized

  10. Modelling of evaporation of a dispersed liquid component in a chemically active gas flow

    NASA Astrophysics Data System (ADS)

    Kryukov, V. G.; Naumov, V. I.; Kotov, V. Yu.

    1994-01-01

    A model has been developed to investigate evaporation of dispersed liquids in chemically active gas flow. Major efforts have been directed at the development of algorithms for implementing this model. The numerical experiments demonstrate that, in the boundary layer, significant changes in the composition and temperature of combustion products take place. This gives the opportunity to more correctly model energy release processes in combustion chambers of liquid-propellant rocket engines, gas-turbine engines, and other power devices.

  11. Numerical analysis of the relaxation of particle and gas phases in dusty supersonic viscous flow

    SciTech Connect

    Elangovan, R.

    1989-01-01

    A numerical method for solving the full dusty gas viscous flow equations is presented. In this method the terms representing drag force, work done by the particles passing through the gas, and heat transfer are evaluated using the trapezoidal rule. The differencing procedure for the remaining terms is similar to the MacCormack explicit predictor-corrector method (MacCormack and Baldwin, 1975). 18 references.

  12. Design and Testing of a Shell-Flow Hollow-Fiber Venting Gas Trap

    NASA Technical Reports Server (NTRS)

    Bue, Grant C.; Cross, Cindy; Hansen, Scott; Vogel, Matthew; Dillon, Paul

    2013-01-01

    A Venting Gas Trap (VGT) was designed, built, and tested at NASA Johnson Space Center to eliminate dissolved and free gas from the circulating coolant loop of the Orion Environmental Control Life Support System. The VGT was downselected from two different designs. The VGT has robust operation, and easily met all the Orion requirements, especially size and weight. The VGT has a novel design with the gas trap made of a five-layer spiral wrap of porous hydrophobic hollow fibers that form a cylindrically shaped curtain terminated by a dome-shaped distal plug. Circulating coolant flows into the center of the cylindrical curtain and flows between the hollow fibers, around the distal plug, and exits the VGT outlet. Free gas is forced by the coolant flow to the distal plug and brought into contact with hollow fibers. The proximal ends of the hollow fibers terminate in a venting chamber that allows for rapid venting of the free gas inclusion, but passively limits the external venting from the venting chamber through two small holes in the event of a long-duration decompression of the cabin. The VGT performance specifications were verified in a wide range of flow rates, bubble sizes, and inclusion volumes. Long-duration and integrated Orion human tests of the VGT are also planned for the coming year.

  13. Unified gas-kinetic scheme for diatomic molecular simulations in all flow regimes

    NASA Astrophysics Data System (ADS)

    Liu, Sha; Yu, Pubing; Xu, Kun; Zhong, Chengwen

    2014-02-01

    A unified gas-kinetic scheme (UGKS) is constructed for both continuum and rarefied flow computations. The underlying principle for the development of UGKS is the direct modeling for the gas evolution process from the kinetic to the hydrodynamic scale, which is used in the flux construction across a cell interface. More specifically, the physical process from the kinetic particle free transport to the hydrodynamic pressure wave propagation is recovered in the flux function. In the previous study, the UGKS has been developed mainly for monatomic gas with particle translational motion only. The construction of time evolution solution is based on the BGK, Shakhov, and ES-BGK models. The UGKS has been validated through extensive numerical tests. In this paper, a UGKS for diatomic gas will be constructed, where the gas-kinetic Rykov model with a Landau-Teller-Jeans-type rotational energy relaxation is used in the numerical scheme. The new scheme will be tested in many cases, such as homogeneous flow relaxation, shock structure calculations, hypersonic flow passing a flat plate, and the flow around a blunt circular cylinder. The analytic, DSMC, and experimental measurements will be used for validating the solutions of UGKS.

  14. Linear stability of the Couette flow of a vibrationally excited gas. 2. viscous problem

    NASA Astrophysics Data System (ADS)

    Grigor'ev, Yu. N.; Ershov, I. V.

    2016-03-01

    Based on the linear theory, stability of viscous disturbances in a supersonic plane Couette flow of a vibrationally excited gas described by a system of linearized equations of two-temperature gas dynamics including shear and bulk viscosity is studied. It is demonstrated that two sets are identified in the spectrum of the problem of stability of plane waves, similar to the case of a perfect gas. One set consists of viscous acoustic modes, which asymptotically converge to even and odd inviscid acoustic modes at high Reynolds numbers. The eigenvalues from the other set have no asymptotic relationship with the inviscid problem and are characterized by large damping decrements. Two most unstable viscous acoustic modes (I and II) are identified; the limits of these modes were considered previously in the inviscid approximation. It is shown that there are domains in the space of parameters for both modes, where the presence of viscosity induces appreciable destabilization of the flow. Moreover, the growth rates of disturbances are appreciably greater than the corresponding values for the inviscid flow, while thermal excitation in the entire considered range of parameters increases the stability of the viscous flow. For a vibrationally excited gas, the critical Reynolds number as a function of the thermal nonequilibrium degree is found to be greater by 12% than for a perfect gas.

  15. Measurement of Concentration Distribution of Hydrogen Gas Flow by Measuring the Intensity of Raman Scattering Light

    NASA Astrophysics Data System (ADS)

    Asahi, Ippei; Ninomiya, Hideki

    An experimental study to visualize and measure the concentration distribution of hydrogen gas flow using the Raman scattering was performed. A Nd:YAG laser of wavelength at 355 nm was used, and the beam pattern was transformed into a rectangle and a sheet beam was formed. The Raman scattered light was observed at a right angle with respect to the laser beam axis using a gated ICCD camera and an interference filter. Shadowgraph images were obtained at the same condition. The Raman scattering light image from atmospheric nitrogen was first acquired and the function of Raman scattering light acquisition and the background light suppression was confirmed. Next, images of the Raman scattering light image and shadowgraph of hydrogen gas discharged from a nozzle into the atmosphere were acquired. The two obtained Raman images were compared and the spatial concentration distribution of the flow of the hydrogen gas at different flow rates was calculated. This method is effective for visualizing the gas flow and measuring the concentration distribution of the Raman active molecules, such as hydrogen gas.

  16. Analysis of spectrum characteristics of optical scintillation in stack gas flow

    NASA Astrophysics Data System (ADS)

    Liu, Wen-Qing; Liu, He-Lai; Zeng, Zong-Yong; Jiang, Yu

    2006-08-01

    Based on the analysis of spectrum characteristics of intensity fluctuations while light beams pass through stack gas flow in an industrial setting, this paper puts emphasis upon discussing the spectrum of optical intensity fluctuations by the variety of particle concentration in stack gas flow. This paper also gives the primary theoretical explanation of the measurement results in the stack of coal-fired utility boilers. Meanwhile, the cross-correlation formula is given as the theoretical basis of velocity measurement by using particle concentration scintillation.

  17. A system for the real time, direct measurement of natural gas flow

    SciTech Connect

    Sowell, T.

    1995-12-31

    PMI/Badger Meter, Inc. with partial sponsorship from the Gas Research Institute, has designed and developed direct measurement total energy flow metering instrumentation. As industry demands for improved accuracy and speed of measurement have increased so has the complexity of the overall hardware and software systems. Considering traditional system approaches, few companies have the in house capability of maintaining a complete system. This paper addresses efforts to implement a direct, total gas energy flow metering system which is simple to use and cost effective.

  18. Role of the gas flow parameters on the uniformity of films produced by PECVD technique

    SciTech Connect

    Martins, R.; Macarico, A.; Ferreira, I.; Fortunato, E.

    1997-07-01

    The aim of this work is to present an analytical model able to interpret the experimental data of the dependence of film's uniformity on the discharge pressure, gas flow and temperature used during the production of thin films by the plasma enhancement chemical vapor deposition technique, under optimized electrode's geometry and electric field distribution. To do so, the gas flow is considered to be quasi-incompressible and inviscous leading to the establishment of the electro-fluid-mechanics equations able to interpret the film's uniformity over the substrate area, when the discharge process takes place in the low power regime.

  19. Temperature and heat transfer solutions for aeromagnetic dusty-gas flow

    SciTech Connect

    Chamkha, A.J. )

    1993-09-01

    Based on temperature and heat transfer solutions derived by Chamkha (1992) for aeromagnetic dusty-gas flows (such as are occurring in many industrial processes), this paper investigates the effect of a transverse magnetic field on the temperature profile, and the wall heat transfer for flow of a dusty gas past an infinite porous flat plate. The fluid phase is assumed to be incompressible and electrically conducting, and the particle phase is assumed to be incompressible and electrically nonconducing; it is also assumed that there is no radiative heat transfer from one particle to another and that the particles do not interact with each other. 6 refs.

  20. Flow regions of granules in Dorfan Impingo filter for gas cleanup

    SciTech Connect

    Kuo, J.T.; Smid, J.; Hsiau, S.S.; Tsai, S.S.; Chou, C.S.

    1999-07-01

    Inside a two-dimensional model of the louvered Dorfan Impingo panel with transparent front and rear walls the flow region of filter granules without gas cross flow were observed. The white PE beads were used as filter granules. Colored PE beads served as tracers. Filter granules were discharged and circulated to the bed. The flow rate of filter medium was controlled by the belt conveyor. The image processing system including a Frame Grabber and JVC videocamera was used to record the granular flow. Every image of motion was digitized and stored in a file. The flow patterns and the quasi-stagnant zones history in the moving granular bed were evaluated. The experiment showed fast central moving region (flowing core) of filter granules and quasi-stagnant zones close to louver walls.