Science.gov

Sample records for gas flow sputtering

  1. Effect of Argon Gas Flow Rate on the Optical and Mechanical Properties of Sputtered Tungsten Thin Film Coatings

    NASA Astrophysics Data System (ADS)

    Vijaya, G.; Muralidhar Singh, M.; Krupashankara, M. S.; Kulkarni, RS

    2016-09-01

    Tungsten thin film coatings were deposited on SS304 substrates by DC magnetron sputtering process. Optical and mechanical properties changes have been studied as a function of varying argon gas flow rate during magnetron sputtering process. The effect of argon flow rate on depositionrate, mechanical and optical properties of the tungsten films prepared at Different power rate was investigated by surface profilometer, nanoindenter, FESEM and UV Vis NIR spectrometer. With increasing argon gas flow rate increases deposition rate and hence higher IR reflectance in IR region and at lower argon gas flow rate the absorptance is higher. The optimized results allows us to select the deposition condition for solar absorptance and thermal emittance for solar thermal applications. The XRD analysis shows that the deposited tungsten thin film coatings were in polycrystalline in nature and surface roughness increases with increase in argon gas flow rate. Nanoindentation test result yields that hardness of DC magnetronsputtered tungsten thin film increases with argon gas flow rate from 200sccm to 500sccm.

  2. 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.

  3. 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.

  4. 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).

  5. Noble gas sputtering calculations using TRIM

    SciTech Connect

    Greene, J.P.; Nemanich, J.; Thomas, G.E.; Schiel, S.L.

    1996-12-31

    In conjunction with our experimental work on saddle field ion sputtering, we have attempted to apply the Monte Carlo program TRIM (Transport of Ions in Matter) to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target production.

  6. 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.

  7. Magnetic and magneto-optical properties of Co/Nb-codoped TiO2 films deposited by gas flow sputtering

    NASA Astrophysics Data System (ADS)

    Sakuma, H.; Nagamatsu, T.; Kashiwakura, T.; Ishii, K.

    2010-04-01

    Titanium dioxide thin films codoped with Co and Nb (Co/Nb-codoped TiO2 films) were fabricated by a low-energy deposition process, gas flow sputtering. No metallic Co or Nb phase was detected by X-ray diffraction and X-ray photoelectron spectroscopy, suggesting that the Co and Nb ions have the oxidation states 2+ and 5+, respectively. The films show a relatively large Faraday rotation and magnetic circular dichroism on the order of 103 deg/cm.

  8. 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.

  9. Reduction of residual gas in a sputtering system by auxiliary sputter of rare-earth metal

    NASA Astrophysics Data System (ADS)

    Li, Dejie

    2002-01-01

    In film deposition by sputtering, the oxidation and nitrification of the sputtered material lead to degradation of film quality, particularly with respect to metal sulfide films. We propose to use auxiliary sputtering as a method to produce a fresh film of rare-earth metal, usually dysprosium (Dy), that absorbs the active gases in a sputtering system, greatly reducing the background pressure and protecting the film from oxidation and nitrification effectively. The influence of the auxiliary sputtering power consumption, sputtering time, and medium gas pressure on the background pressure in the vacuum chamber is investigated in detail. If the auxiliary sputtering power exceeds 120 W and the sputtering time is more than 4 min, the background pressure is only one fourth of the ultimate pressure pumped by an oil diffusion pump. The absorption activity of the sputtered Dy film continues at least an hour after completion of the auxiliary sputter. Applied to film deposition of Ti and ZnS, this technique has been proven to be effective. For the Ti film, the total content of N and O is reduced from 45% to 20% when the auxiliary sputtering power of Dy is 120 W, and the sputtering time is 20 min. In the case of ZnS, the content of O is reduced from 8% to 2%.

  10. Sputtering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    The potential of using the sputtering process as a deposition technique is reviewed; however, the manufacturing and sputter etching aspects are also discussed. The basic mechanism for dc and rf sputtering is described. Sputter deposition is presented in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter etching, target geometry (coating and complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also discussed are some of the specific industrial areas which are turning to sputter deposition techniques.

  11. XPS Depth Profile Analysis of Zn3N2 Thin Films Grown at Different N2/Ar Gas Flow Rates by RF Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Haider, M. Baseer

    2017-01-01

    Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

  12. XPS Depth Profile Analysis of Zn3N2 Thin Films Grown at Different N2/Ar Gas Flow Rates by RF Magnetron Sputtering.

    PubMed

    Haider, M Baseer

    2017-12-01

    Zinc nitride thin films were grown on fused silica substrates at 300 °C by radio frequency magnetron sputtering. Films were grown at different N2/Ar flow rate ratios of 0.20, 0.40, 0.60, 0.80, and 1.0. All the samples have grain-like surface morphology with an average surface roughness ranging from 4 to 5 nm and an average grain size ranging from 13 to16 nm. Zn3N2 samples grown at lower N2/Ar ratio are polycrystalline with secondary phases of ZnO present, whereas at higher N2/Ar ratio, no ZnO phases were found. Highly aligned films were achieved at N2/Ar ratio of 0.60. Hall effect measurements reveal that films are n-type semiconductors, and the highest carrier concentration and Hall mobility was achieved for the films grown at N2/Ar ratio of 0.60. X-ray photoelectron study was performed to confirm the formation of Zn-N bonds and to study the presence of different species in the film. Depth profile XPS analyses of the films reveal that there is less nitrogen in the bulk of the film compared to the nitrogen on the surface of the film whereas more oxygen is present in the bulk of the films possibly occupying the nitrogen vacancies.

  13. 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.

  14. 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.

  15. 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.

  16. Preparation of a heteroepitaxial La{sub x}Sr{sub y}Mn{sub z}O{sub 3}/BiFeO{sub 3} bilayer by r.f. magnetron sputtering with various oxygen gas flow ratios

    SciTech Connect

    Naganuma, H. Ichinose, T.; Begum, H. A.; Sato, S.; Oogane, M.; Ando, Y.; Han, X. F.; Miyazaki, T.; Bae, In-T.

    2014-08-15

    BiFeO{sub 3} (BFO) and La{sub x}Sr{sub y}Mn{sub z}O{sub 3} (LSMO) films were epitaxially grown on SrTiO{sub 3} (100) substrates by r.f. magnetron sputtering with various oxygen gas flow ratios (F{sub O2}). Compositional ratios of each atom in both of BFO and LSMO could be controlled kept to around 10 at.% by changing F{sub O2}. Adjusting the compositional ratio to La{sub 0.35}Sr{sub 0.15}Mn{sub 0.5}O{sub 3} not only increase T{sub c} of LSMO but also produces sufficient oxygen to form a perovskite lattice. For an LSMO/BFO heterostructure, detailed observation by cross sectional transmission electron microscopy (TEM) revealed that the lattice of rhombohedral (SG: R-3c) LSMO was shrank by a clamping effect from the SrTiO{sub 3} substrates, and then the BFO was grown in two layers: (i) an interfacial BFO layer (7 nm thick) with evenly shrunk a-axis and c-axis, and (ii) an upper BFO layer (25 nm thick) expanded along the c-axis. Neither misfit strain nor dislocations appeared at the interface between the shrunken BFO and LSMO layers, and these heterostructures did not show exchange bias. These results suggest that BFO is suitable for a tunneling barrier combine with LSMO electrode.

  17. The influence of N2 flow rate on Ar and Ti Emission in high-pressure magnetron sputtering system plasma

    NASA Astrophysics Data System (ADS)

    How, Soo Ren; Nayan, Nafarizal; Lias, Jais

    2017-03-01

    For ionized physical vapor deposition (known as IPVD) technique, investigation on the ionization mechanism of titanium atoms is very important during the deposition of titanium nitride (TiN) thin film using reactive magnetron sputtering plasma. The introduction of nitrogen gas into the chamber discharge leads to modifications of plasma parameters and ionization mechanism of transition species. In this work, an investigation on the influence of nitrogen flow rate on spectrum properties of argon and titanium during the deposition process have been carried out. The experimental configuration consists of OES and structure of magnetron sputtering device with the turbo molecular pump. A high-pressure magnetron sputtering plasma was used as plasma discharge chamber with various flow rate of nitrogen gas. Optical emission spectroscopy (OES) measurements were employed as plasma diagnostics tool in magnetron sputtering plasma operated at relatively high pressure. OES is a non-invasive plasma diagnostics method and that can detect the atomic and ionic emission during plasma discharge. The flow rate of the Ar and N2 gas are controlled by mass flow controller. The changes of relative emission for both neutral and ionic of argon as well as titanium were observed using optical spectrometer when the nitrogen gas is introduced into the discharged chamber. We found that the titanium emission decreased very rapidly with the flow rate of nitrogen. In addition, the argon emission slightly decreased with the flow rate of nitrogen.

  18. Size controlled deposition of Cu and Si nano-clusters by an ultra-high vacuum sputtering gas aggregation technique

    NASA Astrophysics Data System (ADS)

    Banerjee, A. N.; Krishna, R.; Das, B.

    2008-02-01

    In this paper we have reported the syntheses of copper and silicon nano-clusters by a sputtering-gas-aggregation type growth technique. The process involves typical magnetron sputtering vaporization of target materials followed by an inert gas condensation to form clusters of varying sizes. The size-distributions of the clusters typically follow a normal-distribution and the peak cluster sizes of the distributions depends on several factors, which include gas-flow rate, length of the growth region, deposition pressure etc. We have observed a variation in the peak cluster size with the variation of the gas (argon) flow rates. The experimental values are compared with the existing models and the results are found to be in good agreement. The results are significant since it demonstrates that proper optimization of operation conditions can lead to desired cluster sizes as well as desired cluster-size distributions.

  19. Optical and structural properties of sputter-deposited nanocrystalline Cu2O films: effect of sputtering gas.

    PubMed

    Chandra, R; Chawla, A K; Ayyub, P

    2006-04-01

    We report the effect of the atomic mass of the sputtering gas (He, Ne, Ar, Kr, and Xe) on the structure and optical properties of nanocrystalline cuprous oxide (Cu2O) thin films deposited by dc magnetron sputtering. The crystal structure and surface morphology were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM) respectively. We find that the atomic mass of the sputtering gas significantly affects the primary crystallite size as well as the surface morphology and texture. Optical reflectance and transmission measurements show that the nanocrystalline thin films are transparent over most of the visible region. The HOMO-LUMO gap obtained from optical absorption spectra show a size-dependent quantum shift with respect to the bulk band gap reported for Cu2O (2.1 eV).

  20. Gas-phase clusterization of zinc during magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Abduev, A. Kh.; Akhmedov, A. K.; Asvarov, A. Sh.; Alikhanov, N. M.-R.; Emirov, R. M.; Muslimov, A. E.; Belyaev, V. V.

    2017-01-01

    The processes of gas-phase clusterization of zinc during dc magnetron sputtering of a zinc target in an argon atmosphere have been investigated. The influence of the working gas pressure and magnetron discharge current on the morphology and structure of the precipitates formed on substrates previously cooled to-50°C is studied. It is shown that dense textured (002)Zn layers with a columnar structure are formed at relatively low argon pressures in the chamber ( P = 0.5 Pa) and low discharge currents (100 mA). X-ray amorphous deposits with a fractal coral-like structure arise on substrates at an extremely high argon pressure in the chamber ( P = 5 Pa). An increase in the magnetron discharge current at an operating gas pressure of 5 Pa leads to the formation of polycrystalline layers on substrates; the intensity of the XRD peaks related to crystalline zinc increases with an increase in the discharge current. Possible mechanisms of the structural transformation of Zn deposits are considered.

  1. 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.

  2. TiN films fabricated by reactive gas pulse sputtering: A hybrid design of multilayered and compositionally graded structures

    NASA Astrophysics Data System (ADS)

    Yang, Jijun; Zhang, Feifei; Wan, Qiang; Lu, Chenyang; Peng, Mingjing; Liao, Jiali; Yang, Yuanyou; Wang, Lumin; Liu, Ning

    2016-12-01

    Reactive gas pulse (RGP) sputtering approach was used to prepare TiN thin films through periodically changing the N2/Ar gas flow ratio. The obtained RGPsbnd TiN film possessed a hybrid architecture containing compositionally graded and multilayered structures, composed of hcp Ti-phase and fcc TiN-phase sublayers. Meanwhile, the RGP-TiN film exhibited a composition-oscillation along the film thickness direction, where the Ti-phase sublayer had a compositional gradient and the TiN-phase retained a constant stoichiometric ratio of Ti:N ≈ 1. The film modulation ratio λ (the thicknesses ratio of the Ti and TiN-phase sublayer) can be effectively tuned by controlling the undulation behavior of the N2 partial flow rate. Detailed analysis showed that this hybrid structure originated from a periodic transition of the film growth mode during the reactive sputtering process.

  3. Tuning of magnetization dynamics in sputtered CoFeB thin film by gas pressure

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Huang, Qijun; Liao, Zhiqin; Li, Shandong; Ong, C. K.

    2012-04-01

    The influences of sputtering gas pressure on the high-frequency magnetization dynamics of as-sputtered CoFeB thin films are studied with permeability spectra based on the Landau-Lifshitz-Gilbert (LLG) equation. Results show that with the pressure increasing, both the anisotropy field and resonance frequency have minimums, while the initial permeability shows a maximum. The damping factor deceases monotonously with the pressure increasing, similar as with the coercivity. The high tunability of the damping factor indicates that controlling sputtering gas pressure could be an effective method in tuning the magnetization dynamics. All these dependences on gas pressure are suggested to be related to the inner stress of these sputtered films.

  4. Comprehensive computer model for magnetron sputtering. I. Gas heating and rarefaction

    SciTech Connect

    Jimenez, Francisco J.; Dew, Steven K.

    2012-07-15

    The complex interaction between several variables in magnetron sputtering discharges is a challenge in developing engineering design tools for industrial applications. For instance, at high pressures, rarefaction and gas heating should no longer be neglected for determining several parameters of the process. In this article, we use a comprehensive 3D reactor-scale simulator that incorporates most phenomena of interest in a self-consistent manner to simulate the transport of sputtered particles over a wide range of pressures and powers. Calculations of aluminum deposition rates and metal vapor densities are in reasonable agreement with experiments over a wide range of pressures and powers. Of the elements investigated (Al, Ti, and Cu), copper showed the greatest rarefaction (30%) due to its higher sputtering yield. Titanium, despite a slightly lower sputtering yield than Al, shows a greater rarefaction than aluminum as more particles are reflected from the target as high energy neutrals. In this case, a more efficient energy transfer process is responsible for the higher rarefaction observed in Ti sputtering when compared to Al. The authors also observed that by sputtering at a higher pressure, the probability of electron impact ionization of sputtered particles is increased and speculate about the role of this process in contrast to penning ionization, which is believed to be the dominant ionization mechanism in magnetron sputtering.

  5. 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.

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

    SciTech Connect

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

    2016-05-06

    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:N{sub 2})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.

  7. Sputtered alumina as a novel stationary phase for micro machined gas chromatography columns.

    PubMed

    Haudebourg, R; Matouk, Z; Zoghlami, E; Azzouz, I; Danaie, K; Sassiat, P; Thiebaut, D; Vial, J

    2014-02-01

    Silica and graphite sputtering have previously been reported as novel solid stationary phase deposition techniques for micro gas chromatography columns. As a conventional solid stationary phase in gas chromatography, compatible with sputtering yet so far unreported, alumina was evaluated in this study. Alumina sputtered semi-packed micro columns were fabricated (including an activation step) and proved able to separate a mixture of volatile alkanes (C1-C4 with isomers) in less than 1 min. Kinetic and a thermodynamic evaluation led to calculation of 4,500 theoretical plates for ethane in 1.1 m (HETPmin = 250 μm) and a Gibbs free energy for propane of 30.2 kJ mol(-1), making this stationary phase's properties very close to those observed with silica-sputtered micro columns.

  8. 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.

  9. Gas Flow Detection System

    NASA Technical Reports Server (NTRS)

    Moss, Thomas; Ihlefeld, Curtis; Slack, Barry

    2010-01-01

    This system provides a portable means to detect gas flow through a thin-walled tube without breaking into the tubing system. The flow detection system was specifically designed to detect flow through two parallel branches of a manifold with only one inlet and outlet, and is a means for verifying a space shuttle program requirement that saves time and reduces the risk of flight hardware damage compared to the current means of requirement verification. The prototype Purge Vent and Drain Window Cavity Conditioning System (PVD WCCS) Flow Detection System consists of a heater and a temperature-sensing thermistor attached to a piece of Velcro to be attached to each branch of a WCCS manifold for the duration of the requirement verification test. The heaters and thermistors are connected to a shielded cable and then to an electronics enclosure, which contains the power supplies, relays, and circuit board to provide power, signal conditioning, and control. The electronics enclosure is then connected to a commercial data acquisition box to provide analog to digital conversion as well as digital control. This data acquisition box is then connected to a commercial laptop running a custom application created using National Instruments LabVIEW. The operation of the PVD WCCS Flow Detection System consists of first attaching a heater/thermistor assembly to each of the two branches of one manifold while there is no flow through the manifold. Next, the software application running on the laptop is used to turn on the heaters and to monitor the manifold branch temperatures. When the system has reached thermal equilibrium, the software application s graphical user interface (GUI) will indicate that the branch temperatures are stable. The operator can then physically open the flow control valve to initiate the test flow of gaseous nitrogen (GN2) through the manifold. Next, the software user interface will be monitored for stable temperature indications when the system is again at

  10. Nitrogen-doped p-type ZnO films prepared from nitrogen gas radio-frequency magnetron sputtering

    SciTech Connect

    Tu, M.-L.; Su, Y.-K.; Ma, C.-Y.

    2006-09-01

    Wide band gap nitrogen-doped p-type ZnO films are prepared by radio-frequency magnetron sputtering from a 99.99% purity ZnO target. The sputtering gas is Ar mixed with various flow rates of nitrogen gas. Hole concentrations increase from 1.89x10{sup 15} to 2.11x10{sup 19} cm{sup -3} as the N{sub 2} flow rate decreases from 15 to 6 SCCM (SCCM denotes cubic centimeter per minute at STP), i.e., increasing N{sub 2} flow rate above 6 SCCM decreases the p-type carrier concentration. Microphotoluminescence (PL) spectra peaks are in the near-UV range and change from 384 nm (3.23 eV) to 374 nm (3.32 eV) with increasing N{sub 2} flow rate. The PL peaks agree with the band gap of bulk ZnO, which comes from the recombination of free excitons. Raman spectra show six peaks: 436 (E{sub 2} high-frequency phonon mode for undoped ZnO film), 581 [A{sub 1} (LO) mode in ZnO:N film], 275, 508, 640, and 854 cm{sup -1} (local vibrational modes of Raman features in N-doped ZnO film)

  11. Stress reduction in sputter deposited films using nanostructured compliant layers by high working-gas pressures

    NASA Astrophysics Data System (ADS)

    Karabacak, Tansel; Senkevich, Jay. J.; Wang, Gwo-Ching; Lu, Toh-Ming

    2005-07-01

    We present a strategy of stress reduction in sputter deposited films by a nano-compliant layer at the substrate using physically self-assembled nanostructures obtained at high working-gas pressures prior to the deposition of a continuous film. This technique is all in situ, and the nanostructures are made of the same material as the deposited thin film and requires no lithography process. This nanostructured layer has a lower material density and can act as a compliant layer to reduce the stress of the subsequently deposited continuous film grown under low gas pressure. By using this approach we were able to reduce stress values significantly in sputter deposited tungsten films and the strategy of alternating high and low Ar gas pressures leads to the growth of much thicker films without delamination.

  12. Reactive gas pulsing sputtering process, a promising technique to elaborate silicon oxynitride multilayer nanometric antireflective coatings

    NASA Astrophysics Data System (ADS)

    Farhaoui, A.; Bousquet, A.; Smaali, R.; Moreau, A.; Centeno, E.; Cellier, J.; Bernard, C.; Rapegno, R.; Réveret, F.; Tomasella, E.

    2017-01-01

    The oxynitride materials present a high versatility, which enables their properties to be controlled by tuning their elemental composition. This is the case for silicon oxynitrides used for multilayer antireflective coatings (ARCs), where several thin films with various refractive indexes are needed. Different techniques allow for the modification of the thin film composition. In this paper, we investigate the reactive gas pulsing sputtering process to easily tune the thin film composition, from an oxide to a nitride, by controlling the averaged oxygen flow rate, without reducing the deposition rate, compared to a conventional reactive process (CP). We then demonstrated that the refractive indexes of films deposited by this pulsing process (PP) can be varied in the same range compared to films obtained by CP (from 1.83 to 1.45 at 1.95 eV), whereas their extinction coefficients remain low. Finally, the multilayer ARC has been simulated and optimized by a genetic algorithm for wavelength at 600 nm and for the silicon substrate. Various optimized multilayer (mono-, bi- and tri-layers) structures have been deposited by the PP technique and characterized. They are presented in good agreement with the simulated reflectivity. Hence, the PP allows for an easy depositing tri-layer system with a reasonable deposition rate and low reflectivity (8.1% averaged on 400-750 nm visible light range).

  13. 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.

  14. 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.

  15. Gas Flow Controller

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The Mass Flowmeter is a device used to measure flow of oxygen in spacecraft's life support system. Tylan Corporation's Mass Flow Controller's major application is accurate control of reactive gases-- such as hydrogen, phosphine and silane as they are diffused at extremely high temperatures into silicon wafers. Wafers are ultimately cut up into integrated circuits or "chips" for electronic products. Precise process control afforded by the Mass Flow Controller makes it possible to produce circuit chips of greater performance at lower cost.

  16. The physics of grain-grain collisions and gas-grain sputtering in interstellar shocks

    NASA Technical Reports Server (NTRS)

    Tielens, A. G. G. M.; Mckee, C. F.; Seab, C. G.; Hollenbach, D. J.

    1994-01-01

    Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatter, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes can be much more important in interstellar shocks than vaporization. The sputtering of grains by impacting gas ions is reanalyzed based upon extensive laboratory studies and a theoretically derived 'universal'sputtering relation. The analytical results are compared to available experimental studies of sputtering of graphite/amorphous carbon, SiO2, SiC, Fe, and H2O. Sputtering yields for astrophysically relevant materials as a function of impact energy and ion mass are derived. These yields are also averaged over thermal impact spectrum and simple polynomial fits to the resulting yields as a function of temperature are presented. The derived sputtering yields are similar to those adopted in previous studies, except for graphite near threshold where the new yields are much larger due to a lower adopted binding energy. The ion bombardment will amorphitize the surface layers of interstellar grains. It will also convert graphite into hydrogenated amorphous carbon (HAC) to a depth of 10-20 A. It is suggested that these HAC surfaces are the carriers of the 3.4 micrometer absorption feature in the interstellar medium.

  17. The physics of grain-grain collisions and gas-grain sputtering in interstellar shocks

    NASA Technical Reports Server (NTRS)

    Tielens, A. G. G. M.; Mckee, C. F.; Seab, C. G.; Hollenbach, D. J.

    1994-01-01

    Grain-grain collisions and ion sputtering destroy dust grains in interstellar shocks. An analytical theory is developed for the propagation of shock waves in solids driven by grain-grain collisions, which compares very favorably with detailed numerical calculations. This theory is used to determine the fraction of grain vaporized by a grain-grain collision. Our results predict much less vaporization of colliding grains in interstellar shocks than previous estimates. This theory can also be used to determine the fraction of a colliding grain that melts, shatter, or undergoes a phase transformation to a higher density phase. In particular, the latter two processes can be much more important in interstellar shocks than vaporization. The sputtering of grains by impacting gas ions is reanalyzed based upon extensive laboratory studies and a theoretically derived 'universal'sputtering relation. The analytical results are compared to available experimental studies of sputtering of graphite/amorphous carbon, SiO2, SiC, Fe, and H2O. Sputtering yields for astrophysically relevant materials as a function of impact energy and ion mass are derived. These yields are also averaged over thermal impact spectrum and simple polynomial fits to the resulting yields as a function of temperature are presented. The derived sputtering yields are similar to those adopted in previous studies, except for graphite near threshold where the new yields are much larger due to a lower adopted binding energy. The ion bombardment will amorphitize the surface layers of interstellar grains. It will also convert graphite into hydrogenated amorphous carbon (HAC) to a depth of 10-20 A. It is suggested that these HAC surfaces are the carriers of the 3.4 micrometer absorption feature in the interstellar medium.

  18. 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.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

    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, Ehi, above a threshold energy of sputtering, Eth,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 EhNe 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 EhNe (EhNe,max = 5.3 - 10.3 eV) is lower than Eth,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 Ehi,max multiplied by an exponential factor of -Eth,i/Ehi,max.

  2. Influence of absolute argon and oxygen flow values at a constant ratio on the growth of Zn/ZnO nanostructures obtained by DC reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Masłyk, M.; Borysiewicz, M. A.; Wzorek, M.; Wojciechowski, T.; Kwoka, M.; Kamińska, E.

    2016-12-01

    In the present work we analyze the growth mechanism of Zn/ZnO nanostructured thin films obtained by DC reactive magnetron sputtering with variable absolute gas flow values. Zn target was sputtered at 80 W DC power with variable absolute Ar:O2 flow values at a set ratio, in sccm: 3:0.3, 6:0.6, 8:0.8, 10:1, 15:1.5, 20:2 and 30:3. We obtained unique Zn/ZnO nanoflowers with morphology and properties changing as a function of gas flow values from dendritic/nanopetal structures for low flow to dense porous films for high flow. Zn core/ZnO shell composition results from surface oxidation of Zn crystallites to 4 nm thick ZnO after exposure to atmospheric air that causes an increase in resistivity especially for denser, more porous films. Taking into account that the plasma properties measures using the Langmuir probe and optical emission spectroscopy remain constant as a function of gas flow values, we put forward that the structural evolution of films is influenced by oxygen incorporating into the film surface acting as an inhibitor - incorporating into the films and decreasing crystallite sizes and amorphizing the film structure.

  3. Simple experiment on the sputtering rate of solids in gas discharges

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Reyes, Jorge C.; Korolov, Ihor; Matthews, Lorin S.; Hyde, Truell W.

    2017-06-01

    We present a very simple and sensitive method to measure the sputtering rate of solid materials in stationary low-pressure gas discharges. The method is based on the balance of the centrifugal force and the confinement electric force acting on a single electrically charged dust particle in a rotating environment. We demonstrate the use and sensitivity of this method in a capacitively coupled radio frequency argon discharge. We were able to detect a reduction of 10 nm in the diameter of a single dust particle.

  4. Stability of swirling gas flows

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    1988-01-01

    The stability of inviscid swirling gas flows to small nonaxisymmetric perturbations is considered. For small Brunt-Vaisala frequencies, the problem reduces to the classical Sturm-Liouville form and the oscillation theorem can be applied. The resulting necessary and sufficient stability condition is compared to various criteria in the literature and a limited numerical study of isothermal rigidly rotating Poiseuille flow. For given azimuthal and axial wavenumbers, it is found numerically that the higher inertial modes become unstable for successively lower Rossby numbers and that this sequence of critical values approaches the theoretical value from above.

  5. Single target sputter deposition of alloy nanoparticles with adjustable composition via a gas aggregation cluster source

    NASA Astrophysics Data System (ADS)

    Vahl, Alexander; Strobel, Julian; Reichstein, Wiebke; Polonskyi, Oleksandr; Strunskus, Thomas; Kienle, Lorenz; Faupel, Franz

    2017-04-01

    Alloy nanoparticles with variable compositions add a new dimension to nanoscience and have many applications. Here we suggest a novel approach for the fabrication of variable composition alloy nanoparticles that is based on a Haberland type gas aggregation cluster source with a custom-made multicomponent target for magnetron sputtering. The approach, which was demonstrated here for gold-rich AgAu nanoparticles, combines a narrow nanoparticle size distribution with in operando variation of composition via the gas pressure as well as highly efficient usage of target material. The latter is particularly attractive for precious metals. Varying argon pressure during deposition, we achieved in operando changes of AgAu alloy nanoparticle composition of more than 13 at%. The alloy nanoparticles were characterized by x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. The characteristic plasmon resonances of multilayer nanoparticle composites were analyzed by UV-vis spectroscopy. Tuning of the number of particles per unit area (particle densities) within individual layers showed an additional degree of freedom to tailor the optical properties of multilayer nanocomposites. By extension of this technique to more complex systems, the presented results are expected to encourage and simplify further research based on plasmonic multi-element nanoparticles. The present method is by no means restricted to plasmonics or nanoparticle based applications, but is also highly relevant for conventional magnetron sputtering of alloys and can be extended to in operando control of alloy concentration by magnetic field.

  6. Single target sputter deposition of alloy nanoparticles with adjustable composition via a gas aggregation cluster source.

    PubMed

    Vahl, Alexander; Strobel, Julian; Reichstein, Wiebke; Polonskyi, Oleksandr; Strunskus, Thomas; Kienle, Lorenz; Faupel, Franz

    2017-04-28

    Alloy nanoparticles with variable compositions add a new dimension to nanoscience and have many applications. Here we suggest a novel approach for the fabrication of variable composition alloy nanoparticles that is based on a Haberland type gas aggregation cluster source with a custom-made multicomponent target for magnetron sputtering. The approach, which was demonstrated here for gold-rich AgAu nanoparticles, combines a narrow nanoparticle size distribution with in operando variation of composition via the gas pressure as well as highly efficient usage of target material. The latter is particularly attractive for precious metals. Varying argon pressure during deposition, we achieved in operando changes of AgAu alloy nanoparticle composition of more than 13 at%. The alloy nanoparticles were characterized by x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. The characteristic plasmon resonances of multilayer nanoparticle composites were analyzed by UV-vis spectroscopy. Tuning of the number of particles per unit area (particle densities) within individual layers showed an additional degree of freedom to tailor the optical properties of multilayer nanocomposites. By extension of this technique to more complex systems, the presented results are expected to encourage and simplify further research based on plasmonic multi-element nanoparticles. The present method is by no means restricted to plasmonics or nanoparticle based applications, but is also highly relevant for conventional magnetron sputtering of alloys and can be extended to in operando control of alloy concentration by magnetic field.

  7. Preparation and characteristics of vanadium oxide thin films by controlling the sputtering voltage

    NASA Astrophysics Data System (ADS)

    Wei, Xiongbang; Li, Shibin; Gou, Jun; Dong, Xiang; Yang, Xiaohui; Li, Weizhi; Wang, Tao; Wu, Zhiming; Jiang, Yadong; Chen, Zhi

    2014-06-01

    Influence of sputtering voltage on the deposition process and characteristics of vanadium oxide thin films prepared by reactive DC magnetron sputtering is investigated. The target surface cleaning is controlled by adjusting the sputtering voltage. During the sputtering process, the sputtering voltage increases faster with larger O2 gas flow rate. The sputtering voltage is easy to be stable with larger sputtering voltage. The measured sputtering voltage is correlated to the ion induced secondary electron emission (ISEE) coefficient of the target material. The ISEE coefficient of the oxidized vanadium target surface is lower than the ISEE coefficient of the vanadium metal. The semiconductor to metal (S-M) phase transition temperature decreases with the sputtering voltage, leading to the lower the corresponding temperature of the maximum temperature coefficient of resistance (TCR). By this way, O/V ratio, R, and TCR of VOx films can be controlled by adjusting the sputtering voltage.

  8. 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.

  9. 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}.

  10. Silica sputtering as a novel collective stationary phase deposition for microelectromechanical system gas chromatography column: feasibility and first separations.

    PubMed

    Vial, J; Thiébaut, D; Marty, F; Guibal, P; Haudebourg, R; Nachef, K; Danaie, K; Bourlon, B

    2011-05-27

    Since the late 1970s, approaches have been proposed to replace conventional gas chromatography apparatus with silicon-based microfabricated separation systems. Performances are expected to be improved with miniaturization owing to the reduction of diffusion distances and better thermal management. However, one of the main challenges consists in the collective and reproducible fabrication of efficient microelectromechanical system (MEMS) gas chromatography (GC) columns. Indeed, usual coating processes or classical packing with particulate matters are not compatible with the requirements of collective MEMS production in clean room facilities. A new strategy based on the rerouting of conventional microfabrication techniques and widely used in electronics for metals and dielectrics deposition is presented. The originality lies in the sputtering techniques employed for the deposition of the stationary phase. The potential of these novel sputtered stationary phases is demonstrated with silica sputtering applied to the separation of light hydrocarbons and natural gases. If kinetic characteristics of the sputtered open tubular columns were acceptable with 2500 theoretical plates per meter, the limited retention and resolution of light hydrocarbons led us to consider semipacked sputtered columns with rectangular pillars allowing also significant reduction of typical diffusion distances. In that case separations were greatly improved because retention increased and efficiency was close to 5000 theoretical plates per meter. Copyright © 2010 Elsevier B.V. All rights reserved.

  11. Integration of P-CuO Thin Sputtered Layers onto Microsensor Platforms for Gas Sensing

    PubMed Central

    Presmanes, Lionel; Thimont, Yohann; el Younsi, Imane; Chapelle, Audrey; Blanc, Frédéric; Talhi, Chabane; Bonningue, Corine; Barnabé, Antoine; Menini, Philippe; Tailhades, Philippe

    2017-01-01

    P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH3), acetaldehyde (C2H4O), and nitrogen dioxide (NO2) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde. PMID:28621738

  12. Integration of P-CuO Thin Sputtered Layers onto Microsensor Platforms for Gas Sensing.

    PubMed

    Presmanes, Lionel; Thimont, Yohann; El Younsi, Imane; Chapelle, Audrey; Blanc, Frédéric; Talhi, Chabane; Bonningue, Corine; Barnabé, Antoine; Menini, Philippe; Tailhades, Philippe

    2017-06-16

    P-type semiconducting copper oxide (CuO) thin films deposited by radio-frequency (RF) sputtering were integrated onto microsensors using classical photolithography technologies. The integration of the 50-nm-thick layer could be successfully carried out using the lift-off process. The microsensors were tested with variable thermal sequences under carbon monoxide (CO), ammonia (NH₃), acetaldehyde (C₂H₄O), and nitrogen dioxide (NO₂) which are among the main pollutant gases measured by metal-oxide (MOS) gas sensors for air quality control systems in automotive cabins. Because the microheaters were designed on a membrane, it was then possible to generate very rapid temperature variations (from room temperature to 550 °C in only 50 ms) and a rapid temperature cycling mode could be applied. This measurement mode allowed a significant improvement of the sensor response under 2 and 5 ppm of acetaldehyde.

  13. Characterization of aluminum--aluminum nitride coatings sputter deposited using the pulsed gas process

    SciTech Connect

    Springer, R.W.; Hosford, C.D.

    1982-03-01

    A dc triode magnetron has been used to produce free-standing Al/Al+AlN lamellar foils by sputter deposition. The 5-..mu..m-thick foils produced on both flat substrates as well as curved substrates exhibited good specularity as well as excellent mechanical properties. The pulse spacing was varied from zero to 100-nm spacing. The yield strength of the material was found to obey the Hall--Petch relation sigma/sub y/s = 230+0.07/d1/2, where sigma/sub y/s is in MPa. Auger electron spectroscopy and secondary ion mass spectroscopy indicate that the large flow stress of 230 MPa must be due to grain refinement of the extended source and not an impurity effect. The result is that limitations of masking found in uniaxial flux sources for curved surfaces can be removed allowing the high quality coating of more general shapes.

  14. Characterization of aluminum/aluminum nitride coatings sputter deposited using the pulsed-gas process

    SciTech Connect

    Springer, R.W.; Hosford, C.D.

    1981-01-01

    A dc triode magnetron has been used to produce freestanding Al/Al + AlN lamellar foils by sputter deposition. The 5-..mu..m-thick foils produced on both flat substrates as well as curved substrates exhibited good specularity as well as excellent mechanical properties. The pulse spacing was varied from none to 100-nm spacing. The yield strength of the material was found to obey the Hall-Petch relation sigma/sub ys/ = 230 + .07/d/sup 1/2/, where sigma/sub ys/ is in MPa. Auger electron Spectroscopy and Secondary Ion Mass Spectroscopy indicate that the large flow stress of 230 MPa must be due to grain refinement of the extended source and not an impurity effect. The result is that limitations of masking found in uniaxial flux sources for curved surfaces can be removed allowing the high quality coating of more general shapes.

  15. Gas flow path for a gas turbine engine

    DOEpatents

    Montgomery, Matthew D.; Charron, Richard C.; Snyder, Gary D.; Pankey, William W.; Mayer, Clinton A.; Hettinger, Benjamin G.

    2017-03-14

    A duct arrangement in a can annular gas turbine engine. The gas turbine engine has a gas delivery structure for delivering gases from a plurality of combustors to an annular chamber that extends circumferentially and is oriented concentric to a gas turbine engine longitudinal axis for delivering the gas flow to a first row of blades A gas flow path is formed by the duct arrangement between a respective combustor and the annular chamber for conveying gases from each combustor to the first row of turbine blades The duct arrangement includes at least one straight section having a centerline that is misaligned with a centerline of the combustor.

  16. Gas flow with straight transition line

    NASA Technical Reports Server (NTRS)

    Ovsiannikov, L V

    1951-01-01

    An investigation was conducted on the limiting case of a gas flow when the constant pressure in the surrounding medium is exactly equal to the critical pressure for the given initial state of the gas.

  17. Effect of Argon/Oxygen Flow Rate Ratios on DC Magnetron Sputtered Nano Crystalline Zirconium Titanate Thin Films

    NASA Astrophysics Data System (ADS)

    Rani, D. Jhansi; Kumar, A. GuruSampath; Sarmash, T. Sofi; Chandra Babu Naidu, K.; Maddaiah, M.; Rao, T. Subba

    2016-06-01

    High transmitting, non absorbent, nano crystalline zirconium titanate (ZT) thin films suitable for anti reflection coatings (ARC) were deposited on to glass substrates by direct current (DC) magnetron reactive sputtering technique, under distinct Argon to Oxygen (Ar/O2) gas flow rate ratios of 31/1, 30/2, 29/3 and 28/4, with a net gas flow (Ar + O2) of 32sccm, at an optimum substrate temperature of 250°C. The influence of the gas mixture ratio on the film properties has been investigated by employing x-ray diffraction (XRD), ultra violet visible (UV-vis) spectroscopy, atomic force microscopy (AFM), energy dispersive x-ray analysis (EDX) and four point probe methods. The films showed a predominant peak at 30.85° with (111) orientation. The crystallite size reduced from 22.94 nm to 13.5 nm and the surface roughness increased from 11.53 nm to 50.58 nm with increase in oxygen content respectively. The films deposited at 31/1 and 30/2 showed almost similar chemical composition. Increased oxygen content results an increase in electrical resistivity from 3.59 × 103 to 2.1 × 106 Ωm. The film deposited at Ar/O2 of 28/4 exhibited higher average optical transmittance of 91%, but its refractive index is higher than that of what is required for ARC. The films deposited at 31/1 and 30/2 of Ar/O2 possess higher transmittance (low absorbance) apart from suitable refractive index. Thus, these films are preferable candidates for ARC.

  18. 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.

  19. 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.

  20. Experimental investigation of gas flow type DPAL

    NASA Astrophysics Data System (ADS)

    Yamamoto, Taro; Yamamoto, Fumiaki; Endo, Masamori; Wani, Fumio

    2017-01-01

    We have developed a small-scale, diode-pumped alkali laser with a closed-loop gas circulation device and investigated the effect of gas circulation on the laser output power. The gain cell, with a 5 cm active length, is fitted with antireflection windows, and a cross-flow fan is incorporated inside it. The active medium is composed of cesium, hydrocarbon, and a buffer gas whose total pressure is approximately 2 atmospheres. The laser output power was measured as a function of the gas flow velocity for different buffer gases. In the case of argon, the laser power was strongly dependent on the gas flow velocity, whereas it was almost independent of the gas flow in the case of helium. The maximum output power of the argon buffer was close to that of the helium buffer when the gas velocity exceeded 6 m/s. The experimental results were in good agreement with the numerical simulations.

  1. 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.

  2. Gas flow between immobile contact-surfaces

    NASA Astrophysics Data System (ADS)

    Lemberskii, V. B.

    1982-04-01

    Consideration is given to the problem of leakage through imperfectly connected detachable joints. A method is developed to analyze the rate of gas flow through such joints, with allowance for the displacement of the contact surfaces under the influence of the pressure of the gas flowing through the joint. It is shown that in the case of sufficiently large surface displacements the dependence of gas flow rate on the square of gas pressure inside the joint differs significantly fom a linear dependence, which occurs when the displacement effect is absent.

  3. Dense gas flow in minimum length nozzles

    SciTech Connect

    Aldo, A.C.; Argrow, B.M.

    1995-06-01

    Recently, dense gases have been investigated for many engineering applications such as for turbomachinery and wind tunnels. Supersonic nozzle design can be complicated by nonclassical dense-gas behavior in the transonic flow regime. In this paper, a method of characteristics (MOC) is developed for two-dimensional (planar) and axisymmetric flow of a van der Waals gas. A minimum length nozzle design code is developed that employs the MOC procedure to generate an inviscid wall contour. The van der Waals results are compared to perfect gas results to show the real-gas effects on the flow properties and inviscid wall contours.

  4. 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.

  5. Multipath ultrasonic flow meters for gas measurement

    SciTech Connect

    Saunders, M.P.

    1995-11-01

    This paper gives an introduction to the practical application of ultrasonic gas flow meters. A general outline of the theory and methods applied using multipath flow meters. The multi-path type meter provides state of the art gas flow measurements and its accuracy and reliability satisfy the requirements for custody transfer. A typical multi-path device can achieve accuracies better than 0.2%.

  6. Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation.

    PubMed

    Antón, Ricardo López; González, Juan A; Andrés, Juan P; Normile, Peter S; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M; De Toro, José A

    2017-03-11

    Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved.

  7. Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation

    PubMed Central

    Antón, Ricardo López; González, Juan A.; Andrés, Juan P.; Normile, Peter S.; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M.; De Toro, José A.

    2017-01-01

    Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved. PMID:28336895

  8. 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.

  9. Scale effects in gas nano flows

    NASA Astrophysics Data System (ADS)

    Barisik, Murat; Beskok, Ali

    2014-05-01

    Most previous studies on gas transport in nano-scale confinements assume dynamic similarity with rarefied gas flows, and employ kinetic theory based models. This approach is incomplete, since it neglects the van der Waals forces imposed on gas molecules by the surfaces. Using three-dimensional molecular dynamics (MD) simulations of force driven gas flows, we show the significance of wall force field in nano-scale confinements by defining a new dimensionless parameter (B) as the ratio of the wall force-penetration length to the channel height. Investigation of gas transport in different nano-channels at various Knudsen numbers show the importance of wall force field for finite B values, where the dynamic similarity between the rarefied and nano-scale gas flows break down. Comparison of MD results employing molecularly structured three-dimensional walls versus reflection of gas molecules from a two-dimensional planar surface with Maxwell distribution show that the nano-confinement effects cannot be resolved by the latter approach, frequently used in kinetic theory calculations. Molecularly structured walls determine the bulk flow physics by setting a proper tangential momentum accommodation coefficient, and they also determine the transport in the near wall region. Gas nano-flows with finite B exhibit significant differences in the local density and velocity profiles, affecting the mass flow rate and the formation of Knudsen's minimum in nano-channels.

  10. Influence of discharge voltage on the sensitivity of the resultant sputtered NiO thin films toward hydrogen gas

    NASA Astrophysics Data System (ADS)

    Khalaf, Mohammed K.; Mutlak, Rajaa H.; Khudiar, Ausama I.; Hial, Qahtan G.

    2017-06-01

    Nickel oxide thin films were deposited on glass substrates as the main gas sensor for H2 by the DC sputtering technique at various discharge voltages within the range of 1.8-2.5 kV. Their structural, optical and gas sensing properties were investigated by XRD, AFM, SEM, ultraviolet visible spectroscopy and home-made gas sensing measurement units. A diffraction peak in the direction of NiO (200) was observed for the sputtered films, thereby indicating that these films were polycrystalline in nature. The optical band gap of the films decreased from 3.8 to 3.5 eV when the thickness of the films was increased from 83.5 to 164.4 nm in relation to an increase in the sputtering discharge voltage from 1.8 to 2.5 kV, respectively. The gas sensitivity performance of the NiO films that were formed was studied and the electrical responses of the NiO-based sensors toward different H2 concentrations were also considered. The sensitivity of the gas sensor increased with the working temperature and H2 gas concentration. The thickness of the NiO thin films was also an important parameter in determining the properties of the NiO films as H2 sensors. It was shown in this study that NiO films have the capability to detect H2 concentrations below 3% in wet air, a feature that allows this material to be used directly for the monitoring of the environment.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Gas flows in Galaxies: Mergers Versus Bars

    NASA Astrophysics Data System (ADS)

    Ellison, S. L.; Patton, D. R.; Nair, P.; Mendel, J. T.; Scudder, J. M.; Simard, L.

    2013-10-01

    In this contribution, I will review the latest results of our ongoing work to study the central gas flows in merging galaxies, focusing on triggered star formation, presence of an AGN and changes in the gas-phase metallicity. Results from a sample of close galaxy pairs are compared with bar driven gas inflows in order to quantify the relative importance of hierarchical versus secular processes.

  17. Gas flow rates through transtracheal ventilation catheters.

    PubMed

    Marr, Jonathan K; Yamamoto, Loren G

    2004-07-01

    The purpose of the study was to measure gas flow rates using different methods of transtracheal ventilation. Wall oxygen flow (WOF) at 10 and 15L/min, and a self-inflating ventilation bag (SIVB) were used to deliver gas flow through three transtracheal catheters: 13, 14, and 16 gauge (5 trials each). WOF mean gas flow rates (L/min) through the 16G, 14G, 13G catheters, respectively were: 15.7, 15.7, 16.8 at 15L/min, 10.5, 10.5, 10.3 at 10 L/min, and 5.7, 7.5, 7.7 via SIVB. SIVB gas flow was not continuous since it required the bag to reinflate, which reduces its calculated flow rate. A 500 cc tidal volume can be delivered within 3 seconds (WOF) and 5 seconds (SIVB). Catheter size did not substantially affect gas flow rates (Poiseuille's law not applicable). Transtracheal ventilation is best done by using WOF, but if a device to perform this is not available, then an SIVB may still be sufficient.

  18. The effects of the pressure and the oxygen content of the sputtering gas on the structure and the properties of zinc oxy-nitride thin films deposited by reactive sputtering of zinc

    NASA Astrophysics Data System (ADS)

    Jiang, Nanke; Georgiev, Daniel G.; Jayatissa, Ahalapitiya H.

    2013-02-01

    Zinc nitride and oxy-nitride thin films were prepared by reactive magnetron rf sputtering of zinc in either nitrogen-argon or nitrogen-argon-oxygen ambient. The effects of varying the total sputtering pressure and the oxygen fraction in the total sputtering gas mixture on the microstructure, electrical and optical properties were investigated. With increasing the sputtering pressure, the dominant phase comprising the film material changes from the crystalline zinc nitride phase to crystalline zinc oxide. The characteristic pressure, at which this change in the dominant phase is observed, decreases with the increase of the oxygen fraction in the total sputtering gas mixture. The increase of the oxygen content in the films (from 5 at.% to a maximum of 40 at.%) and the downward shift in the optical absorption edge (from 920 to 400 nm), combined with the x-ray diffraction data, support these observations, indicating the controllable fabrication of an oxy-nitride film material. Correlations between the films’ fabrication conditions, including post-deposition annealing, their structure and composition, and their electrical properties are examined as well.

  19. Morphology control of tungsten nanorods grown by glancing angle RF magnetron sputtering under variable argon pressure and flow rate

    NASA Astrophysics Data System (ADS)

    Khedir, Khedir R.; Kannarpady, Ganesh K.; Ishihara, Hidetaka; Woo, Justin; Ryerson, Charles; Biris, Alexandru S.

    2010-09-01

    Morphologically novel tungsten nanorods (WNRs) with the co-existence of two crystalline phases, α-W (thermodynamically stable) and β-W, were fabricated by glancing angle RF magnetron sputtering technique under various Ar pressures and flow rates. For these nanorods, a significant variation in their morphology and surface roughness was observed. These structures could be useful in a wide range of applications such as field emission, robust superhydrophobic coatings, energy, and medicine.

  20. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    NASA Astrophysics Data System (ADS)

    Anders, André

    2017-05-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become "poisoned," i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.

  1. Stripped interstellar gas in cluster cooling flows

    NASA Technical Reports Server (NTRS)

    Soker, Noam; Bregman, Joel N.; Sarazin, Craig L.

    1991-01-01

    It is suggested that nonlinear perturbations which lead to thermal instabilities in cooling flows might start as blobs of interstellar gas which are stipped out of cluster galaxies. Assuming that most of the gas produced by stellar mass loss in cluster galaxies is stripped from the galaxies, the total rate of such stripping is roughly 100 solar masses/yr, which is similar to the rates of cooling in cluster cooling flows. It is possible that a substantial portion of the cooling gas originates as blobs of interstellar gas stripped from galaxies. The magnetic fields within and outside of the low-entropy perturbations may help to maintain their identities by suppressing both thermal conduction and Kelvin-Helmholtz instabilities. These density fluctuations may disrupt the propagation of radio jets through the intracluster gas, which may be one mechanism for producing wideangle-tail radio galaxies.

  2. 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.

  3. 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.

  4. 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.

  5. Spatial distribution of particles sputtered from single crystals by gas cluster ions

    NASA Astrophysics Data System (ADS)

    Nazarov, A. V.; Chernysh, V. S.; Nordlund, K.; Djurabekova, F.; Zhao, J.

    2017-09-01

    The results of molecular dynamics simulations of the bombardment of the Cu (100) and Mo (100) single-crystals by 10 keV Ar cluster ions of different sizes are presented in this paper. Spatial distributions of sputtered material were calculated. The anisotropy of the angular distributions of sputtered atoms was revealed. It was found that the character of the anisotropy is different for Cu and Mo targets. The reasons leading to this anisotropy are discussed according to the dependences of the angular distributions on the cluster size and on the target material.

  6. Sputter-ion plating of coatings for protection of gas-turbine blades against high-temperature oxidation and corrosion

    NASA Technical Reports Server (NTRS)

    Coad, J. P.; Restall, J. E.

    1982-01-01

    Considerable effort is being devoted to the development of overlay coatings for protecting critical components such as turbine blades against high-temperature oxidation, corrosion, and erosion damage in service. The most commercially advanced methods for depositing coatings are electron-beam evaporation and plasma spraying. Sputter-ion plating (SIP) offers a potentially cheaper and simpler alternative method for depositing overlays. Experimental work on SIP of Co-Cr-Al-Y and Ni-Cr-Al-Ti alloy coatings is described. Results are presented of metallographic assessment of these coatings, and of the results obtained from high-velocity testing using a gas-turbine simulator rig.

  7. 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 flow...

  8. 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 as...

  9. 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 as...

  10. Rotationally symmetric viscous gas flows

    NASA Astrophysics Data System (ADS)

    Weigant, W.; Plotnikov, P. I.

    2017-03-01

    The Dirichlet boundary value problem for the Navier-Stokes equations of a barotropic viscous compressible fluid is considered. The flow region and the data of the problem are assumed to be invariant under rotations about a fixed axis. The existence of rotationally symmetric weak solutions for all adiabatic exponents from the interval (γ*,∞) with a critical exponent γ* < 4/3 is proved.

  11. Gas flow headspace liquid phase microextraction.

    PubMed

    Yang, Cui; Qiu, Jinxue; Ren, Chunyan; Piao, Xiangfan; Li, Xifeng; Wu, Xue; Li, Donghao

    2009-11-06

    There is a trend towards the use of enrichment techniques such as microextraction in the analysis of trace chemicals. Based on the theory of ideal gases, theory of gas chromatography and the original headspace liquid phase microextraction (HS-LPME) technique, a simple gas flow headspace liquid phase microextraction (GF-HS-LPME) technique has been developed, where the extracting gas phase volume is increased using a gas flow. The system is an open system, where an inert gas containing the target compounds flows continuously through a special gas outlet channel (D=1.8mm), and the target compounds are trapped on a solvent microdrop (2.4 microL) hanging on the microsyringe tip, as a result, a high enrichment factor is obtained. The parameters affecting the enrichment factor, such as the gas flow rate, the position of the microdrop, the diameter of the gas outlet channel, the temperatures of the extracting solvent and of the sample, and the extraction time, were systematically optimized for four types of polycyclic aromatic hydrocarbons. The results were compared with results obtained from HS-LPME. Under the optimized conditions (where the extraction time and the volume of the extracting sample vial were fixed at 20min and 10mL, respectively), detection limits (S/N=3) were approximately a factor of 4 lower than those for the original HS-LPME technique. The method was validated by comparison of the GF-HS-LPME and HS-LPME techniques using data for PAHs from environmental sediment samples.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Subsonic Gas Flow Past A Wing Profile

    NASA Technical Reports Server (NTRS)

    Christianovich, S. A.; Yuriev, I. M.

    1950-01-01

    The use of the linearized equations of Chaplygin to calculate the subsonic flow of a gas permits solving the problem of the flow about a wing profile for absence and presence of circulation. The solution is obtained in a practical convenient form that permits finding all the required magnitudes for the gas flow (lift, lift moment velocity distribution over the profile, and critical Mach number). This solution is not expressed in simple closed form; for a certain simplifying assumption, however, the equations of Chaplygin can be reduced to equations with constant coefficients, and solutions are obtained by using only the mathematical apparatus of the theory of functions of a complex variable. The method for simplifying the equations was pointed out by Chaplygin himself. These applied similar equations to the solution of the flow problem and obtained a solution for the case of the absence of circulation.

  17. 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

  18. Potential sputtering of ionic species from rare gas solids by multiply charged ion impact

    NASA Astrophysics Data System (ADS)

    Fukai, K.; Fujita, S.; Tachibana, T.; Koizumi, T.; Hirayama, T.

    2010-03-01

    The interaction of low-energy multiply charged Arq + (q <= 7) ions with a solid Ne surface is experimentally studied. Desorption of very large cluster ions Nen + (n > 100) is observed. The size distribution of smaller (n = 1-3) cluster ions depends strongly on the charge state of the incident ion, whereas that of larger (n > 7) cluster ions exhibits no dependence on the charge state, indicating that desorption of large cluster ions is due to kinetic sputtering. The potential sputtering yield is estimated by analyzing the size distribution of the desorbed cluster ions. The results suggest that the ion desorption mechanism, which is known as desorption induced by electronic transitions, can also be applied to explain the present results.

  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. Ultrasonic meters measure gas pipeline flow

    SciTech Connect

    1995-04-01

    New ultrasonic meters from Stork Ultrasonic Technologies, Houston are improving pipeline gas flow measurements, custody transfers, process gas flow measurements, and flare gas applications. The meters are easy to install, extremely accurate, and all feature realtime measurements. This meter (Gassonic 400) is designed for use in 8-in. to 64-in. gas pipelines and features a dual transducer device which uses the absolute digital travel time method of pulse transmission. Wide band piezoceramic transducers are used in this bi-directional, single bounce system which includes pulse verification and high-speed electronic processing by a central processing unit. Measuring values of this meter are obtained by direct digital measurement of travel time of each individual ultrasonic pulse which covers a pre-determined distance between two transducers inserted in the pipe wall. These transducers cause negligible flow restriction and absolute digital reference and excellent repeatability is possible without adjustment or re-calibration. Dozens of measurements can be processed so that average output values are updated every second during use. It is a field-programmable meter for variations in site parameters, presentation of service diagnostics, user selected velocity or quantity outputs, and has standard analog and digital interfaces. Also, it is suitable for swirl measurement or compensation. Since it relies on a reflection method, the ultrasonic meter allows easy, one-sided insertion and it is suitable for hot-tapping. This instrument is especially useful in gas blending stations, compressor control, leak detection, salt dome storage applications, pipeline balancing, and additive injection systems.

  1. 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.

  2. 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.

  3. 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...) 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. 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...

  5. A Comparative High-Resolution Electron Microscope Study of Ag Clusters Produced by a Sputter-Gas Aggregation and Ion Cluster Beam Technique

    NASA Astrophysics Data System (ADS)

    Hohl, Georg-Friedrich; Hihara, Takehiko; Sakurai, Masaki; Oishi, Takashi; Wakoh, Kimio; Sumiyama, Kenji; Suzuki, Kenji

    1994-03-01

    Ag clusters were formed by a sputter-gas-aggregation process [H. Haberland et al..: J. Vac. Sci. Technol. A 10 (1992) 3266] and the ionized cluster beam (ICB) [T. Takagi: Ionized-Cluster Beam Deposition and Epitaxy (Noyes, Park Ridge, 1988)] technique. The Ag clusters deposited on collodion-coated microgrids were investigated by high-resolution transmission electron microscopy. The diameter of those clusters, d, ranges from 1 nm up to about 10 nm for specimens produced by the sputter-gas aggregation technique, depending on the sputter condition and the deposition time. Comparable times of the ICB deposition lead to a broader distribution up to d≈20 nm, suggesting the formation of islands with extremely flat shapes. High percentages of crystalline particles obtained by both techniques are either single crystals or multiple twins with clear lattice images.

  6. 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

    2015-10-07

    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.

  7. Titanium aluminum nitride sputtered by HIPIMS

    NASA Astrophysics Data System (ADS)

    Weichart, Juergen; Lechthaler, Markus

    2012-09-01

    TiAlN was sputtered reactively by HIPIMS in the target compositions Ti/Al 33/67 and 50/50 using a modified OC Oerlikon Balzers INNOVA coating equipment. The resulting film properties like deposition rate, surface roughness, hardness, Young's modulus, wear, and film stress were analyzed as function of the nitrogen gas flow, pressure, target-substrate distance, and substrate bias. Furthermore, the films were characterized by X-ray diffraction and secondary electron microscopy of the cross section and the surface appearance. The process characteristics and film properties were compared with pulsed DC sputtering under the same conditions.

  8. 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.

  9. The effect of sputtering gas pressure on the structure and optical properties of MgNiO films grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Xie, Wuze; Jiao, Shujie; Wang, Dongbo; Gao, Shiyong; Wang, Jinzhong; Yu, Qingjiang; Li, Hongtao

    2017-05-01

    In this study, MgNiO thin films were grown on quartz substrates by radio frequency (RF) magnetron sputtering. The influence of different sputtering pressures on the crystalline and optical properties of MgNiO thin films has been studied. X-ray diffraction measurement indicates that the MgNiO films are cubic structure with (200) preferred orientation. UV-vis transmission spectra show that all the MgNiO thin films show more than 75% transmission at visible region, and the absorption edges of all thin films locate at solar-blind region (220 nm-280 nm). The lattice constant and Mg content of MgNiO samples were calculated using X-ray diffraction and transmission spectra data. The phase separation is observed both in the X-ray diffraction patterns and transmission spectra, and the phase separation is studied in detail based on the crystal growth theory and sputtering process.

  10. Lateral variation of target poisoning during reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Güttler, D.; Grötzschel, R.; Möller, W.

    2007-06-01

    The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during dc magnetron deposition of TiN in an Ar /N2 atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target racetrack compared to the target center and edge. The findings are reproduced by model calculations. In the racetrack, the balance of reactive gas injection and sputter erosion is shifted toward erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.

  11. Stochastic Modeling of Buoyancy driven Gas Flow Pattern: Can Continuum Models describe Channelized Gas Flow?

    NASA Astrophysics Data System (ADS)

    Geistlinger, H. W.; Samani, S.

    2010-12-01

    The injection of gases into the subsurface has become an important research topic in groundwater remediation technology, e.g. air sparging, and in CCS-technology, e.g. CO2-sequestration into saline aquifers. In both cases risk assessment is based on 2-phase flow modeling assuming that the stochastic gas flow patterns can be described by the continuum approach. As Cinar et al. (2009) have stated: “The fundamental understanding of drainage, as it applies to CO2 sequestration process, is limited primarily by the lack of well characterized experiments that allow a detailed classification of the microscopic flow regimes”. In case of air sparging the two important flow regimes are capillary fingering and viscous fingering. Using pore scale network modeling Ewing and Berkowitz (1998) were able to describe the transition from capillary fingering (= incoherent channelized flow) to viscous fingering (= coherent channelized flow). In order to investigate the stability of buoyancy-driven gas flow and the transition between coherent channelized flow and incoherent channelized flow we conducted high-resolution optical bench scale experiments. Our main results, which are in strong contradiction to the commonly used continuum models (CM) are: (1) Capillary trapping can already occur during injection and at the front of the plume (Lazik and Geistlinger, 2008) (2) Gas clusters or bubbles can be mobile (incoherent gas flow) and immobile (capillary trapping), and (3) Incoherent gas flow can not be described by a generalized Darcy law (Geistlinger et al., 2006, 2009). Glass et al. (2000) conducted CO2-gas injection experiments. Based on their experimental results they also questioned the validity of CM to describe coherent and incoherent gas flow and the validity of homogeneous stability analysis to predict channel width, channel number and channel velocity in heterogeneous porous media. Despite these findings there is an ongoing controversial discussion in the literature about

  12. 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.

  13. 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.

  14. Gas flow modelling through clay and claystones

    NASA Astrophysics Data System (ADS)

    Alonso, E.

    2012-12-01

    Large scale gas flow experiments conducted in connection with nuclear waste disposal research have shown the dominant effect of "minor" details such as interfaces, contacts and layer boundaries. Even if the scale of the analysis is highly reduced, in search of homogeneous point-like conditions, a systematic development of preferential paths is very often reported. Small size samples become boundary value problems. Preferential paths, when their thickness is modified by the stress-strain response of the media, under the combined action of stress and fluid pressure changes, become highly conductive features for gas flow. The development of preferential paths for fluid flow has been approached in a simple manner by embedding a discontinuity feature into an otherwise continuous element which models clay or claystone matrix behavior. The joint is activated when tensile strains develop in the continuous element. Then, hydraulic properties (permeability, retention behavior) are modified by means of laws derived from the physics of flow in discontinuities. The outlined idea was incorporated into a full Thermo-Hydro-Mechanical finite element code (CODE_BRIGHT) which has a wide range of capabilities for the modeling of two-phase flow in elasto-viscoplastic porous materials. A particular aspect which required attention is the modeling of expansive and shrinkage behavior induced by suction changes. In this way, healing effects during re-saturation may be simulated. Two experimental programs on clay shale samples, performed under triaxial stress conditions will be discussed. In the first case samples of Opalinus shale were subjected to a series of gas pulse decay tests during the application of stress paths involving a particular sequence of confining stress and shearing up to failure. In the second experimental program, performed on a tertiary mudstone from the Norwegian shelf, attention was paid to the effect of bedding-induced anisotropy. Experimental results will be

  15. Unsteady Swirling Flows in Gas Turbines

    DTIC Science & Technology

    1980-05-01

    surge, aeroacoustic noise and flutter, at present, little is known about this phenomenon -- despite its importance to the aircraft engine overall...Implications of Conclusions Obtained During Phase I Effort as related to Aircraft Gas Turbines ..................................... 16 5. Written...found to occur in various aircraft engine components. This flow instability, dubbed here as "Vortex Whistle", is one of the most subtle and treacherous

  16. Modeling of the Reactive High Power Impulse Magnetron Sputtering (HiPIMS) process

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Raadu, Michael; Brenning, Nils; Minea, Tiberiu

    2015-09-01

    Reactive high power impulse magnetron sputtering (HiPIMS) provides both a high ionization fraction of the sputtered material and a high dissociation fraction of the molecular gas. We demonstrate this through an ionization region model (IRM) of the reactive Ar/O2 HiPIMS discharge with a titanium target. We explore the influence of oxygen dilution on the discharge properties such as electron density, the ionization fraction of the sputtered vapor and the oxygen dissociation fraction. We discuss the important processes and challenges for more detailed modeling of the reactive HiPIMS discharge. Furthermore, we discuss experimental observations during reactive high power impulse magnetron sputtering sputtering (HiPIMS) of Ti target in Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on the reactive gas flow rate, pulse repetition frequency and discharge voltage. The discharge current increases with decreasing repetition frequency and increasing flowrate of the reactive gas.

  17. 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.

  18. Effects of Nitrogen Flow Ratio on the Properties of Radiofrequency-Sputtered InGaN Films

    NASA Astrophysics Data System (ADS)

    Wang, J.; Hou, X. H.; Shi, X. J.; Zhu, J.

    2015-04-01

    Indium gallium nitride (InGaN) thin films have been prepared on quartz glass substrates at various nitrogen flow ratios by radiofrequency (rf) reactive magnetron sputtering. At lower nitrogen flow ratio of 30%, the as-grown InGaN film exhibits an amorphous structure. As the nitrogen flow ratio increases from 40% to 60%, grazing-incidence x-ray diffraction (GIXRD) peaks corresponding to wurtzite InGaN are observed. At higher nitrogen flow ratios of 80% and 100%, the films exhibit highly oriented fine columnar structure and the texture of the wurtzite structure changes from (0002) to (). The nitrogen flow ratio has a significant effect on the crystalline orientation and the intensity of the peak signals. A redshift of the absorption edge occurs, and the bandgap E g tends to decrease with increasing nitrogen flow ratio. The sheet resistance R s and the resistivity ρ of the InGaN films decrease due to the contribution of the comparatively narrow intercrystalline barriers. All the InGaN films have low mobility values, and show n-type conductivity with carrier concentration depending on the nitrogen flow ratio.

  19. Flows of gas through a protoplanetary gap.

    PubMed

    Casassus, Simon; van der Plas, Gerrit; Sebastian Perez, M; Dent, William R F; Fomalont, Ed; Hagelberg, Janis; Hales, Antonio; Jordán, Andrés; Mawet, Dimitri; Ménard, Francois; Wootten, Al; Wilner, David; Hughes, A Meredith; Schreiber, Matthias R; Girard, Julien H; Ercolano, Barbara; Canovas, Hector; Román, Pablo E; Salinas, Vachail

    2013-01-10

    The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models predict that the process produces a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10 astronomical units (AU) in radius (1 AU is the Earth-Sun distance), surrounded by a particularly large gap and a disrupted outer disk beyond 140 AU. This disruption is indicative of a perturbing planetary-mass body at about 90 AU. Radio observations indicate that the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology. The high stellar accretion rate would deplete the inner disk in less than one year, and to sustain the observed accretion matter must therefore flow from the outer disk and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk. Here we report observations of diffuse CO gas inside the gap, with denser HCO(+) gas along gap-crossing filaments. The estimated flow rate of the gas is in the range of 7 × 10(-9) to 2 × 10(-7) solar masses per year, which is sufficient to maintain accretion onto the star at the present rate.

  20. Flows of gas through a protoplanetary gap

    NASA Astrophysics Data System (ADS)

    Casassus, Simon; van der Plas, Gerrit; M, Sebastian Perez; Dent, William R. F.; Fomalont, Ed; Hagelberg, Janis; Hales, Antonio; Jordán, Andrés; Mawet, Dimitri; Ménard, Francois; Wootten, Al; Wilner, David; Hughes, A. Meredith; Schreiber, Matthias R.; Girard, Julien H.; Ercolano, Barbara; Canovas, Hector; Román, Pablo E.; Salinas, Vachail

    2013-01-01

    The formation of gaseous giant planets is thought to occur in the first few million years after stellar birth. Models predict that the process produces a deep gap in the dust component (shallower in the gas). Infrared observations of the disk around the young star HD 142527 (at a distance of about 140 parsecs from Earth) found an inner disk about 10 astronomical units (AU) in radius (1 AU is the Earth-Sun distance), surrounded by a particularly large gap and a disrupted outer disk beyond 140 AU. This disruption is indicative of a perturbing planetary-mass body at about 90 AU. Radio observations indicate that the bulk mass is molecular and lies in the outer disk, whose continuum emission has a horseshoe morphology. The high stellar accretion rate would deplete the inner disk in less than one year, and to sustain the observed accretion matter must therefore flow from the outer disk and cross the gap. In dynamical models, the putative protoplanets channel outer-disk material into gap-crossing bridges that feed stellar accretion through the inner disk. Here we report observations of diffuse CO gas inside the gap, with denser HCO+ gas along gap-crossing filaments. The estimated flow rate of the gas is in the range of 7 × 10-9 to 2 × 10-7 solar masses per year, which is sufficient to maintain accretion onto the star at the present rate.

  1. Permeable Gas Flow Influences Magma Fragmentation Speed.

    NASA Astrophysics Data System (ADS)

    Richard, D.; Scheu, B.; Spieler, O.; Dingwell, D.

    2008-12-01

    Highly viscous magmas undergo fragmentation in order to produce the pyroclastic deposits that we observe, but the mechanisms involved remain unclear. The overpressure required to initiate fragmentation depends on a number of physical parameters, such as the magma's vesicularity, permeability, tensile strength and textural properties. It is clear that these same parameters control also the speed at which a fragmentation front travels through magma when fragmentation occurs. Recent mathematical models of fragmentation processes consider most of these factors, but permeable gas flow has not yet been included in these models. However, it has been shown that permeable gas flow through a porous rock during a sudden decompression event increases the fragmentation threshold. Fragmentation experiments on natural samples from Bezymianny (Russia), Colima (Mexico), Krakatau (Indonesia) and Augustine (USA) volcanoes confirm these results and suggest in addition that high permeable flow rates may increase the speed of fragmentation. Permeability from the investigated samples ranges from as low as 5 x 10-14 to higher than 9 x 10- 12 m2 and open porosity ranges from 16 % to 48 %. Experiments were performed for each sample series at applied pressures up to 35 MPa. Our results indicate that the rate of increase of fragmentation speed is higher when the permeability is above 10-12 m2. We confirm that it is necessary to include the influence of permeable flow on fragmentation dynamics.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Modeling of heavy-gas effects on airfoil flows

    NASA Technical Reports Server (NTRS)

    Drela, Mark

    1992-01-01

    Thermodynamic models were constructed for a calorically imperfect gas and for a non-ideal gas. These were incorporated into a quasi one dimensional flow solver to develop an understanding of the differences in flow behavior between the new models and the perfect gas model. The models were also incorporated into a two dimensional flow solver to investigate their effects on transonic airfoil flows. Specifically, the calculations simulated airfoil testing in a proposed high Reynolds number heavy gas test facility. The results indicate that the non-idealities caused significant differences in the flow field, but that matching of an appropriate non-dimensional parameter led to flows similar to those in air.

  8. Vehicle exhaust gas clearance by low temperature plasma-driven nano-titanium dioxide film prepared by radiofrequency magnetron sputtering.

    PubMed

    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.

  9. 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

  10. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  11. Fabrication of size-selected Pd nanoclusters using a magnetron plasma sputtering source

    SciTech Connect

    Ayesh, A. I.; Qamhieh, N.; Ghamlouche, H.; Thaker, S.; El-Shaer, M.

    2010-02-15

    We report on the fabrication of palladium (Pd) nanoclusters using a dc magnetron sputtering source. Plasma sputtering vaporizes the target's material forming nanoclusters by inert gas condensation. The sputtering source produces ionized nanoclusters that enable the study of the nanoclusters' size distribution using a quadrupole mass filter. In this work, the dependence of Pd nanoclusters' size distribution on various source parameters, such as the sputtering discharge power, inert gas flow rate, and aggregation length have been investigated. This work demonstrates the ability of tuning the palladium nanoclusters' size by proper optimization of the source operation conditions. The experimental nanocluster sizes are compared with a theoretical model that reveals the growth of large nanoclusters from 'embryos' by a two-body collision. The model is valid for a specific range of deposition parameters (low inert gas flow rates and aggregation lengths equal or below 70 mm).

  12. 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.

  13. 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.

  14. 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.

  15. Influence of Nitrogen Flow Rates on the Structure, Hardness, and Electrical Resistivity of HfN Coatings by DC Sputtering

    NASA Astrophysics Data System (ADS)

    García-González, Leandro; Zamora-Peredo, Luis; Flores-Ramírez, Nelly; Garnica-Romo, María Guadalupe; Hernández-Torres, Julián

    2015-04-01

    HfN hard coatings on Corning glass substrates were obtained using DC sputtering. A power of 200 W was used keeping the flow rate of argon at 10 sccm and varying the nitrogen flow rates at 2.5, 3.5, 5.0, and 7.5 sccm to analyze differences in the hardness and electrical resistivity values, explaining variations in relation to structural changes. To achieve this, the Vickers microhardness test, x-ray diffraction, Raman, atomic force microscopy, and high resistivity measurements were used. At 2.5 sccm, the hardness value was shown to reach a maximum value of 20 GPa, and a minimum electrical resistivity of 6.5 × 108 µΩcm. Furthermore, as the flow is increased, the hardness values gradually decrease (until a value of 8 GPa is reached), the fracture toughness increase (until a value of 0.3 MPa√m is reached), and the electrical resistivity reaches its maximum at 1.52 × 1012 μΩcm. These variations are attributed to the evolution that the HfN phase progressively undergoes from a crystal orientation at (111) to an amorphous phase. In addition, the presence of tensile stresses, which tend to favor electrical resistivity, was identified. The average RMS roughness increased from 3.76 to 10.69 nm as the nitrogen flow was increased. Finally, the Raman spectroscopy confirmed the presence of the HfN phase.

  16. 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.

  17. Clusters as a diagnostics tool for gas flows

    NASA Astrophysics Data System (ADS)

    Ganeva, M.; Kashtanov, P. V.; Kosarim, A. V.; Smirnov, B. M.; Hippler, R.

    2015-06-01

    The example of a gas flowing through an orifice into the surrounding rarefied space is used to demonstrate the possibility of using clusters for diagnosing gas flows. For the conditions studied (it takes a cluster velocity about the same time to relax to the gas velocity as it does to reach the orifice), information on the flow parameters inside the chamber is obtained from the measurement of the cluster drift velocity after the passage through an orifice for various gas consumptions. Other possible uses of clusters in gas flow diagnostics are discussed as well.

  18. Characterization of helium/argon working gas systems in a radiofrequency glow discharge atomic emission source. Part I: Optical emission, sputtering and electrical characteristics

    NASA Astrophysics Data System (ADS)

    Christopher, Steven J.; Hartenstein, Matthew L.; Marcus, R. Kenneth; Belkin, Mikhail; Caruso, Joseph A.

    1998-08-01

    Studies are performed to determine the influence of discharge gas composition (helium/argon working gas mixtures) on the analyte emission signal intensities, sputtering rates, and DC-bias characteristics of an analytical radiofrequency glow discharge atomic emission spectroscopy (RF-GD-AES) source. As the partial pressure of He is increased from 0 to 15 torr, increased emission intensity is observed for a range of bulk and trace elements in NIST 1250 SRM (low alloy steel), regardless of the base pressure of Ar in the source (5 and 9 torr). In contrast to increases in analyte emission intensity of up to 300%, counterindicative decreases in the sputtering rates on the order of about 30-50% are observed. The magnitude of these effects depends on both the partial pressure of helium introduced to the source and the total pressure of the He and Ar gases. Use of relative emission yield (REY) to normalize changes in emission intensity to sputtering rates indicates that excitation efficiencies increase under these conditions. Increases in average electron energy and temperature appear to control this response. Decreases in both analyte emission intensities and sputter rates occur with increasing He partial pressure when the total pressure in the cell remains fixed (11 torr in these studies). Emission yields for the fixed pressure, mixed gas plasmas decrease as the partial pressure of He (He/Ar ratio) in the RF-GD source increases. In this case, decreases in electron number densities appear to dictate the lower REYs. Measurement of DC-bias values at the sample surface provide understanding with respect to the observed changes in sputtering rates as well as suggest the origins of changes in plasma electron energetics. Use of a diamond stylus profilometer provides both the quantitative sputter rate information as well as qualitative insights into the use of mixed gas plasmas for enhanced depth profiling capabilities. The analyte emission characteristics of these mixed gas

  19. A microfluidic chip for generating reactive plasma at gas-gas interface formed in laminar flow

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Tsukasaki, Katsuki; Kumagai, Shinya; Sasaki, Minoru

    2015-01-01

    A gas-gas interface is used for generating a localized reactive plasma flow at an atmospheric pressure. A microfluidic chip is fabricated as the reactor integrating a small plasma source located upstream. Within a Y-shaped microchannel, a discharging gas flows with a chemical gas. Owing to the small width of the microchannel, the gas flow is stabilized in a laminar flow. The resultant gas-gas interface is formed in the area where two gases flow facing each other activating the chemical gas through the energetic species in the discharging gas. A characteristic stream pattern is observed as the etching profile of a carbon film with a sub-µm sharp step change that can be explained by the spatial distribution of the reactive oxygen. This etching profile is different from that obtained when plasma discharging occurs near the channel exit being affected by the turbulent flow.

  20. 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.

  1. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Zhang, Angran; Huang, Mingju

    2017-03-01

    High-quality vanadium oxide ( VO2) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO2 has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO2 thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm.

  2. Comparison of induced damage, range, reflection, and sputtering yield between amorphous, bcc crystalline, and bubble-containing tungsten materials under hydrogen isotope and noble gas plasma irradiations

    NASA Astrophysics Data System (ADS)

    Saito, Seiki; Nakamura, Hiroaki; Tokitani, Masayuki

    2017-01-01

    Binary-collision-approximation simulation of hydrogen isotope (i.e., hydrogen, deuterium, and tritium) and noble gas (i.e., helium, neon, and argon) injections into tungsten materials is performed. Three tungsten structures (i.e., amorphous, bcc crystalline, and helium bubble-containing structures) are prepared as target materials. Then, the trajectories of incident atoms, the distribution of recoil atoms, the penetration depth range of incident atoms, the sputtering yield, and the reflection rate are carefully investigated for these target materials.

  3. Correlations between structure, composition and electrical properties of tungsten/tungsten oxide periodic multilayers sputter deposited by gas pulsing

    NASA Astrophysics Data System (ADS)

    Potin, Valérie; Cacucci, Arnaud; Martin, Nicolas

    2017-01-01

    W/WOx multilayered thin films have been deposited by DC reactive sputtering using the reactive gas pulsing process. It is implemented to produce regular alternations of metal-oxide compounds at the nanometric scale. Structure and growth have been investigated by high resolution transmission electron microscopy, scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and electron energy loss spectroscopy. Regularity of tungsten-based alternations, quality of interfaces as well as oxygen presence through the multilayered structure have been determined and linked to the growth conditions. Chemical information was obtained from the energy dispersive X-ray spectroscopy and low-loss electron energy loss spectroscopy. As they can be related to the chemical composition of the periodic layers, the position and the broadening of the bulk plasmon peak were studied. For the smallest periods (<10 nm), the presence of oxygen has been pointed out in the metal-rich layer whereas for the thickest ones (100 nm), pure metal is only present. Finally, relationships have been established between in situ growth conditions, structural and chemical parameters and electrical properties in periodic multilayers.

  4. Gradient Driven Flow: Lattice Gas, Diffusion Equation and Measurement Scales

    DTIC Science & Technology

    2001-01-01

    03-200 1 Journal Article (refereed) 2001 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Gradient Driven Flow : Lattice Gas, Diffusion Equation and...time regime, the collective motion exhibits an onset of oscillation. 15. SUBJECT TERMS Diffusion; Fick’s Law; Gradient Driven Flow ; Lattice Gas 16...Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18 20010907 062 Gradient driven flow : lattice gas, diffusion equation and measurement scales R.B

  5. Analysis and Applications of Radiometric Forces in Rarefied Gas Flows

    DTIC Science & Technology

    2010-06-16

    Forces in Rarefied Gas Flows 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Sergey F. Gimelshein & Natalia E. Gimelshein (ERC, Inc...Forces in Rarefied Gas Flows Sergey F. Gimelshein∗, Natalia E. Gimelshein∗, Andrew D. Ketsdever† and Nathaniel P. Selden∗∗ ∗ERC, Inc, Edwards AFB, CA 93524...geometries. Keywords: Radiometric force, shear, ES-BGK equation PACS: 51.10.+y INTRODUCTION Rarefied gas flow surrounding a thin vane with a temperature

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Reactive high power impulse magnetron sputtering: combining simulation and experiment

    NASA Astrophysics Data System (ADS)

    Kozak, Tomas; Vlcek, Jaroslav

    2016-09-01

    Reactive high-power impulse magnetron sputtering (HiPIMS) has recently been used for preparation of various oxide films with high application potential, such as TiO2, ZrO2, Ta2O5, HfO2, VO2. Using our patented method of pulsed reactive gas flow control with an optimized reactive gas inlet, we achieved significantly higher deposition rates compared to typical continuous dc magnetron depositions. We have developed a time-dependent model of the reactive HiPIMS. The model includes a depth-resolved description of the sputtered target (featuring sputtering, implantation and knock-on implantation processes) and a parametric description of the discharge plasma (dissociation of reactive gas, ionization and return of sputtered atoms and gas rarefaction). The model uses a combination of experimental and simulation data as input. We have calculated the composition of the target and substrate for several deposition conditions. The simulations predict a reduced compound coverage of the target in HiPIMS compared to the continuous dc sputtering regime which explains the increased deposition rate. The simulations show that an increased dissociation of oxygen in a HiPIMS discharge is beneficial to achieve stoichiometric films on the substrate at high deposition rates.

  12. Effect of Al content, substrate temperature and nitrogen flow on the reactive magnetron co-sputtered nanostructure in TiAlN thin films intended for use as barrier material in DRAMs

    NASA Astrophysics Data System (ADS)

    Jalali, Reza; Parhizkar, Mojtaba; Bidadi, Hasan; Naghshara, Hamid; Hosseini, Seyd Reza; Jafari, Majid

    2015-03-01

    TiAlN thin films were deposited by using the reactive magnetron co-sputtering method whit individual Ti and Al targets, where the Ti and the Al targets were simultaneously powered by using DC and RF sources, respectively. the electrical resistivity and the structural and microstructural properties of the deposited TiAlN thin films and the effects of Al content, substrate temperature and nitrogen gas flow rate on those properties were investigated. At a low flow rate of nitrogen gas (0.51 sccm), the electrical resistivity of the films was found to increase with increasing AC power, but at a high flow rate of nitrogen gas, it was found to decrease. The structural and microstructural analyses performed by using X-ray diffraction and scanning electron microscopy (SEM) showed that with increasing substrate temperature from room temperature to 400 ℃, the films prepared at 400 ℃ have a crystalline structure while those prepared at room temperature had an amorphous nature. Also, the SEM analysis revealed that with decreasing AC power and increasing nitrogen flow rate, the size of the grains in the prepared films become larger.

  13. Axial flow gas turbine engine combustor

    SciTech Connect

    Shekleton, J.R.; Sawyer, K.W.

    1991-02-19

    This patent describes a gas turbine engine. It comprises: radial compressor means for compressing air entering through a compressor inlet opening; axial turbine means in axially spaced relation to the radial compressor means; the radial compressor means being operatively associated with the axial turbine means; radial combustor means intermediate the radial compressor means and axial turbine means; turbine nozzle means proximate the axial turbine means for directing gases of combustion thereto; the radial combustor means defining a radial combustion space in communication with both the radial compressor means and the turbine nozzle means. The radial combustor means including means for introducing compressed air generally tangentially into the radial combustion space upstream of the turbine nozzle means and at a point radially outwardly of the turbine nozzle means and the turbine nozzle means being disposed radially inwardly of the radial combustion space to define a generally radial flow path therebetween. The radial combustor means generating the gases of combustion by combusting fuel from a source and air from the radial compressor means; and fuel injection means operatively associated with the radial combustor means radially outwardly of the turbine nozzle means for injecting a fuel/air mixture generally tangentially into the radial combustion space; whereby a tangential swirl flow is established within the radial combustion space.

  14. Deposition profile of Ti film inside a trench and its correlation with gas-phase ionization in high-pressure magnetron sputtering

    SciTech Connect

    Nafarizal, N.; Takada, N.; Nakamura, K.; Sago, Y.; Sasaki, K.

    2006-11-15

    This article reports the relationship between the degree of ionization of Ti in the gas phase and the thickness profile of Ti film inside a trench in magnetron sputtering deposition. A conventional magnetron sputtering plasma source was used for depositing Ti films inside trenches formed on rf-biased SiO{sub 2} substrates. It was found that a high bottom coverage was obtained when a high gas pressure and a long distance between the target and the substrate were employed for the deposition. On the other hand, at a short distance between the target and the substrate, the bottom coverage was small and was almost independent of the gas pressure. The deposition profile was compared with the spatial distributions of Ti and Ti{sup +} densities measured by laser-induced fluorescence (LIF) imaging spectroscopy. The LIF results revealed that the density ratio of Ti{sup +} to Ti in the downstream region increased with the gas pressure up to 0.3, while in the upstream region, it was small (<0.05) and was roughly constant with the gas pressure. In the case with the enhanced density ratio of 0.3, the flux ratio of Ti{sup +} to Ti was estimated to be 4.4. Hence, it was concluded that, with a high gas pressure and a long distance between the target and substrate, the deposition profile with a high bottom coverage was obtained by accelerating Ti{sup +} toward the bottom of the trench. The high-pressure magnetron sputtering discharge is useful for enhancing the degree of ionization and the bottom coverage.

  15. Effect of gas channel height on gas flow and gas diffusion in a molten carbonate fuel cell stack

    NASA Astrophysics Data System (ADS)

    Hirata, Haruhiko; Nakagaki, Takao; Hori, Michio

    An investigation is made of the relationships between the gas channel height, the gas-flow characteristics, and the gas-diffusion characteristics in a plate heat-exchanger type molten carbonate fuel cell stack. Effects of the gas channel height on the uniformity and pressure loss of the gas flow are evaluated by numerical analysis using a computational fluid dynamics code. The effects of the gas channel height on the distribution of the reactive gas concentration in the direction perpendicular to the channel flow are evaluated by an analytical solution of the two-dimensional concentration transport equation. Considering the results for uniformity and pressure loss of the gas flow, and for distribution of the reactive gas concentration, the appropriate gas channel height in the molten carbonate fuel cell stack is investigated.

  16. 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.

  17. 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 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. 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.

  19. MgZnO/ZnO Two-Dimensional Electron Gas Photodetectors Fabricated by Radio Frequency Sputtering.

    PubMed

    Hwang, J D; Yang, C C; Chu, C M

    2017-07-19

    MgZnO/ZnO two-dimensional electron gas (2DEG) structures with ZnO annealed at various temperatures (600-900 °C) and photodetectors (PDs) with and without a 2DEG structure were fabricated using a radio frequency magnetron sputtering system. It was found that the carrier concentration and mobility increase with the annealing temperature owing to the improved crystalline in ZnO; however, high-temperature (800 °C or higher) annealing can degrade the crystalline of the ZnO layer. Hall measurements showed that compared with that of bulk ZnO, the sheet carrier concentration of the 2DEG sample increased from 1.3 × 10(13) to 1.2 × 10(14) cm(-2), and the mobility was enhanced from 5.1 to 17.5 cm(2)/V s. This is because the channel layer is the total thickness (300 nm) in bulk ZnO, whereas the carriers are confined to a 45 nm region beneath the MgZO layer in the 2DEG sample, confirming the 2DEG behavior at the MgZnO/ZnO interface. The PDs with 2DEG structures demonstrate a higher ultraviolet (UV) response and a UV/visible rejection ratio that is six times larger than that of the PDs without a 2DEG structure. The 2DEG structure also induces a photocurrent gain, which results in a 240% quantum efficiency for the 310 nm incident wavelength. The related mechanism is elucidated with a band diagram.

  20. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    DOE PAGES

    Anders, André

    2017-03-21

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron

  1. Physical properties and surface/interface analysis of nanocrystalline WO3 films grown under variable oxygen gas flow rates

    SciTech Connect

    Vemuri, R. S.; Carbjal-Franco, G.; Ferrer, D. A.; Engelhard, Mark H.; Ramana, Chintalapalle V.

    2012-10-15

    Nanocrystalline WO3 films were grown by reactive magnetron sputter-deposition in a wide range of oxygen gas flow rates while keeping the deposition temperature fixed at 400 oC. The physical characteristics of WO3 films were evaluated using grazing incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR) and transmission electron microscopy (TEM) measurements. Physical characterization indicates that the thickness, grain size, and density of WO3 films are sensitive to the oxygen gas flow rate during deposition. XRD data indicates the formation of tetragonal WO3 films. The grain size increases from 21 to 25 nm with increasing oxygen gas flow rate to 65%, at which point the grain size exhibits a decreasing trend to attain the lowest value of 15 nm at 100% oxygen. TEM analysis provides a model consisting of isotropic WO3 film (nanocrystalline)-SiO2 interface (amorphous)-Si(100) substrate. XRR simulations, which are based on this model, provide excellent agreement to the experimental data indicating that the normalized thickness of WO3 films decreases with the increasing oxygen gas flow rate. The density of WO3 films increases with increasing oxygen gas flow rate.

  2. 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.

  3. Magnetron-Sputtered Amorphous Metallic Coatings

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Mehra, M.; Khanna, S. K.

    1985-01-01

    Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

  4. Dynamics of the sputtering of water from ice films by collisions with energetic xenon atoms.

    PubMed

    Killelea, Daniel R; Gibson, K D; Yuan, Hanqiu; Becker, James S; Sibener, S J

    2012-04-14

    The flow of energy from the impact site of a heavy, translationally energetic xenon atom on an ice surface leads to several non-equilibrium events. The central focus of this paper is on the collision-induced desorption (sputtering) of water molecules into the gas-phase from the ice surface. Sputtering is strongly activated with respect to xenon translational energy, and a threshold for desorption was observed. To best understand these results, we discuss our findings in the context of other sputtering studies of molecular solids. The sputtering yield is quite small; differential measurements of the energy of xenon scattered from ice surfaces show that the ice efficiently accommodates the collisional energy. These results are important as they quantitatively elucidate the dynamics of such sputtering events, with implications for energetic non-equilibrium processes at interfaces.

  5. Peel strength of sputtered FCCL(Flexible Copper Clad Laminate) using Ar:O2 mixed gas preprocessing and a Ni-Cr seed layer

    NASA Astrophysics Data System (ADS)

    Ahn, Woo-Young; Jang, Joong Soon

    2014-07-01

    The PI surface was modified with ion beams in a vacuum chamber to increase the surface area. A two-way Design of Experiments ("DOE") was performed by varying the DC power and changing the proportion of O2 gas with respect to the Ar reactive gas and measuring the peel strength between the PI layer and the plated Cu layer. The results showed that increasing the voltage level and applying mixed Ar-O2 gas makes the PI surface substantially rough, which increases the Van der Waals force as well as the chemical bonding strength. Using the oxygen gas makes the amorphous structure in the Cu layer sputtered. However, Cu plating with a high electrical current may remedy this, resulting in a good crystalline direction. It was also found that reducing the proportion of Cr in the Ni-Cr seed layer incurs a great decrease in the peel strength after the reflow process, although it requires just one etching.

  6. 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

  7. High-power sputtering employed for film deposition

    NASA Astrophysics Data System (ADS)

    Shapovalov, V. I.

    2017-07-01

    The features of high-power magnetron sputtering employed for the films’ deposition are reviewed. The main physical phenomena accompanying high-power sputtering including ion-electron emission, gas rarefaction, ionization of sputtered atoms, self-sputtering, ion sound waves and the impact of the target heating are described.

  8. 40 CFR 89.416 - Raw exhaust gas flow.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Measurement of the air flow and the fuel flow by suitable metering systems (for details see SAE J244. This... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Raw exhaust gas flow. 89.416 Section 89.416 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS...

  9. Gas flow driven by thermal creep in dusty plasma.

    PubMed

    Flanagan, T M; Goree, J

    2009-10-01

    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.

  10. 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).

  11. Characterization of thin MoO3 films formed by RF and DC-magnetron reactive sputtering for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Yordanov, R.; Boyadjiev, S.; Georgieva, V.; Vergov, L.

    2014-05-01

    The present work discusses a technology for deposition and characterization of thin molybdenum oxide (MoOx, MoO3) films studied for gas sensor applications. The samples were produced by reactive radio-frequency (RF) and direct current (DC) magnetron sputtering. The composition and microstructure of the films were studied by XPS, XRD and Raman spectroscopy, the morphology, using high resolution SEM. The research was focused on the sensing properties of the sputtered thin MoO3 films. Highly sensitive gas sensors were implemented by depositing films of various thicknesses on quartz resonators. Making use of the quartz crystal microbalance (QCM) method, these sensors were capable of detecting changes in the molecular range. Prototype QCM structures with thin MoO3 films were tested for sensitivity to NH3 and NO2. Even in as-deposited state and without heating the substrates, these films showed good sensitivity. Moreover, no additional thermal treatment is necessary, which makes the production of such QCM gas sensors simple and cost-effective, as it is fully compatible with the technology for producing the initial resonator. The films are sensitive at room temperature and can register concentrations as low as 50 ppm. The sorption is fully reversible, the films are stable and capable of long-term measurements.

  12. Effect of mixed gas environment on structure and optical properties of Co-doped ZnO RF- sputtered thin films

    NASA Astrophysics Data System (ADS)

    Malapati, V.; Singh, R.

    2017-05-01

    Thin films of Co doped ZnO thin films have been deposited on fused quartz substrates by radio-frequency magnetron sputtering in mixed gas environment of Ar+ N2 with increase in nitrogen gas content in sputtering chamber up to 100%. The as deposited show the hexagonal wurtzite structure of ZnO with (002) peak along c-axis, without any indication of secondary phase of Co or N2 in ZnO matrix. The surface morphology of the films show dense microstructure. With increase in nitrogen gas composition the films show decrease in average grain size for as deposited films. The room temperature transmittance spectra of as deposited films varies about ˜92-87% show decrease with increase in nitrogen in the films. The estimated direct band gap of the films varies in the range between 4.91 -3.75 eV. The band gap show decrease with increase in nitrogen component in the films is attributed that nitrogen acts as dopant in ZnO matrix along with Co in host ZnO matrix.

  13. 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.

  14. Optical Diagnostics of Nonequilibrium Phenomena in Highly Rarefied Gas Flows

    NASA Astrophysics Data System (ADS)

    Niimi, Tomohide

    2003-05-01

    The necessity of non-intrusive measurement of the thermodynamic variables in rarefied gas flows has motivated the development of optical diagnostics, such as electron beam fluorescence, laser induced fluorescence, coherent anti-Stokes Raman scattering, and so on. These spectroscopic methods have enabled to detect the nonequilibrium in the gas flows, based on the internal energy distributions obtained from spectral profiles. In this paper, the laser-based techniques for detection of the nonequilibrium phenomena in the highly rarefied gas flows and some results obtained by us are described.

  15. Flow of Gas Through Turbine Lattices

    NASA Technical Reports Server (NTRS)

    Deich, M E

    1956-01-01

    This report is concerned with fluid mechanics of two-dimensional cascades, particularly turbine cascades. Methods of solving the incompressible ideal flow in cascades are presented. The causes and the order of magnitude of the two-dimensional losses at subsonic velocities are discussed. Methods are presented for estimating the flow and losses at high subsonic velocities. Transonic and supersonic flows in lattices are then analyzed. Some three-dimensional features of the flow in turbines are noted.

  16. PC Windows finite element modeling of landfill gas flow

    SciTech Connect

    Mull, S.R.; Lang, R.J.; Vigil, S.A.; Cota, H.

    1996-09-01

    A two dimensional demonstration program, GAS, has been developed for the solution of landfill gas (LFG) flow problems on a personal computer (PC). The program combines a Windows{trademark} graphical user interface, object oriented programming (OOP) techniques, and finite element modeling (FEM) to demonstrate the practicality of performing LFG flow modeling on the PC. GAS is demonstrated on a sample LFG problem consisting of a landfill, one gas extraction well, the landfill liner, cap, and surrounding soil. Analyses of the program results are performed for successively finer grid resolutions. Element flux imbalance, execution time, and required memory are characterized as a function of grid resolution.

  17. Effect of gas flow rate on titanium sponge reaction

    NASA Astrophysics Data System (ADS)

    Wang, Zhiliang; Feng, Gaoping; Wang, Mingdong; Hong, Yanji

    2017-08-01

    This paper expounds the important application of titanium sponge adsorption in inert gas purification, the reaction mechanism of titanium with nitrogen and oxygen was introduced. Explored the relationship between the absorption capacity of sponge titanium on the active gas in air samples and the gas flow rate. The model of sponge titanium for flowing air absorption was established by data analysis. The designed experiment verified the relationship between the titanium processing capacity and the gas collecting device. Finally, the influence of the mass of the sponge titanium on the degassing capacity was studied through experiments.

  18. Gas Flow Simulation in GCB Chambers Featuring Hot Gas Energy

    NASA Astrophysics Data System (ADS)

    Mori, Tadashi; Iwamoto, Katsuharu; Kawano, Hiromichi; Tanaka, Yasunori

    A hot gas simulation in self-blast type GCBs was performed and revised. As a result, it was foundto be important to consider the thermodynamic and transport properties of SF6-PTFE gas at high pressures and temperatures. Moreover, modelling arc diameters are also important in the chamber. They have become the main factors in determining the rise of puffer pressure in self-blast type GCBs, while they were not relevant in conventional puffer-type GCBs.

  19. Scaling of multiphase pipeline flow behavior at high gas density

    SciTech Connect

    Crowley, C.J.

    1988-01-01

    This report contains data that demonstrates the scaling of flow regime, pressure drop, and holdup multiphase flow with pipe diameter. In addition, entrance length effects, the onset of liquid entrainment, and interfacial shear modeling at high gas density are studied for purposes of validating multiphase flow design methods. Stratified, slug and annular flow regimes have been observed. Air, freon, and water have been used to represent pipeline fluids.

  20. 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.

  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. Lattice Boltzmann simulation of rarefied gas flows in microchannels

    NASA Astrophysics Data System (ADS)

    Zhang, Yonghao; Qin, Rongshan; Emerson, David R.

    2005-04-01

    For gas flows in microchannels, slip motion at the solid surface can occur even if the Mach number is negligibly small. Since the Knudsen number of the gas flow in a long microchannel can vary widely and the Navier-Stokes equations are not valid for Knudsen numbers beyond 0.1, an alternative method that can be applicable to continuum, slip and transition flow regimes is highly desirable. The lattice Boltzmann equation (LBE) approach has recently been expected to have such potential. However, some hurdles need to be overcome before it can be applied to simulate rarefied gas flows. The first major hurdle is to accurately model the gas molecule and wall surface interactions. In addition, the Knudsen number needs to be clearly defined in terms of LBE properties to ensure that the LBE simulation results can be checked against experimental measurements and other simulation results. In this paper, the Maxwellian scattering kernel is adopted to address the gas molecule and surface interactions with an accommodation coefficient (in addition to the Knudsen number) controlling the amount of slip motion. The Knudsen number is derived consistently with the macroscopic property based definition. The simulation results of the present LBE model are in quantitative agreement with the established theory in the slip flow regime. In the transition flow regime, the model captures the Knudsen minimum phenomenon qualitatively. Therefore, the LBE can be a competitive method for simulation of rarefied gas flows in microdevices.

  3. 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.

  4. Computations of ideal and real gas high altitude plume flows

    NASA Technical Reports Server (NTRS)

    Feiereisen, William J.; Venkatapathy, Ethiraj

    1988-01-01

    In the present work, complete flow fields around generic space vehicles in supersonic and hypersonic flight regimes are studied numerically. Numerical simulation is performed with a flux-split, time asymptotic viscous flow solver that incorporates a generalized equilibrium chemistry model. Solutions to generic problems at various altitude and flight conditions show the complexity of the flow, the equilibrium chemical dissociation and its effect on the overall flow field. Viscous ideal gas solutions are compared against equilibrium gas solutions to illustrate the effect of equilibrium chemistry. Improved solution accuracy is achieved through adaptive grid refinement.

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

    NASA Technical Reports Server (NTRS)

    Kunze, J. F.; Suckling, D. H.; Copper, C. G.

    1972-01-01

    Flow tests were conducted on models of the gas core (cavity) reactor. Variations in cavity wall and injection configurations 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. All tests were run in the down-firing direction so that gravitational effects simulated the acceleration effect of a rocket. Results show that acceptable flow patterns with high 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 along the cavity wall, using louvered or oblique-angle-honeycomb injection schemes.

  6. 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.

  7. 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.

  8. Phase-locked measurements of gas-liquid horizontal flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Matar, Omar; Markides, Christos

    2014-11-01

    A flow of gas and liquid in a horizontal pipe can be described in terms of various flow regimes, e.g. wavy stratified, annular or slug flow. These flow regimes appear at characteristic gas and liquid Reynolds numbers and feature unique wave phenomena. Wavy stratified flow is populated by low amplitude waves whereas annular flow contains high amplitude and long lived waves, so called disturbance waves, that play a key role in a liquid entrainment into the gas phase (droplets). In a slug flow regime, liquid-continuous regions travel at high speeds through a pipe separated by regions of stratified flow. We use a refractive index matched dynamic shadowgraphy technique using a high-speed camera mounted on a moving robotic linear rail to track the formation and development of features characteristic for the aforementioned flow regimes. We show that the wave dynamics become progressively more complex with increasing liquid and gas Reynolds numbers. Based on the shadowgraphy measurements we present, over a range of conditions: (i) phenomenological observations of the formation, and (ii) statistical data on the downstream velocity distribution of different classes of waves. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. Sputter deposition of nanocrystalline beta-SiC films and molecular dynamics simulations of the sputter process.

    PubMed

    Ziebert, Carlos; Ye, Jian; Ulrich, Sven; Prskalo, Alen-Pilip; Schmauder, Siegfried

    2010-02-01

    Thin nanocrystalline films of silicon carbide (SiC) have been deposited on Si substrates by rf magnetron sputtering in pure Ar atmosphere. Simultaneously classical molecular dynamics (MD) simulations of sputtering of beta-SiC by Ar atoms were performed using IMD and Materials Explorer software with a combination of the Tersoff and the Ziegler-Biersack-Littmark (ZBL) potential in order to get more insight into the sputter process. In experiments the bias voltage (0 to -40 V) has been varied at constant substrate temperature of 900 degrees C to investigate the influence on the composition, the constitution and the mechanical properties of crystalline beta-SiC films. At second the substrate temperature has been varied between 900 degrees C and 100 degrees C to find the minimum substrate temperature that is needed to get nanocrystalline beta-SiC under the applied sputter conditions (ceramic SiC target, 300 W rf power, 18 cm target-substrate distance, 50 sccm Ar gas flow, 0.26 Pa total gas pressure). The films have been characterized by electron probe micro-analysis (EPMA), X-ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM). Hardness and residual stress have been investigated by nanoindentation and wafer bending. In the MD simulations the sputter yield was determined as a function of the energy of the incident Ar atoms (in the interesting range for sputter deposition, i.e., 50-1000 eV). To our knowledge this is the first time that the sputter yield of a SiC target was determined as a function of the energy of the incident Ar atoms in the low energy range by using MD simulations and compared with experimental results.

  14. 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.

  15. 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.

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

    SciTech Connect

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

    2016-09-15

    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.

  17. Influence of oxygen flow rate on structural, optical and electrical properties of copper oxide thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gaewdang, Thitinai; Wongcharoen, Ngamnit

    2017-06-01

    In this research, copper oxide thin films were prepared by reactive dc magnetron sputtering method on glass substrates with oxygen flow rate in the range of 1-10 sccm. From XRD patterns, formation of Cu2O cubic structure or CuO monoclinic structure was controlled by adjusting oxygen flow rate. Nanocrystallite size of the as-grown films was observed by AFM. From transmittance spectra, direct energy gap varied between 1.97 and 2.55 eV. Electrical conductivity and Hall effect measurements were performed on the films with van der Pauw configuration. The positive sign of the Hall coefficient confirmed the p-type conductivity in all studied films. Important electrical parameters of films as a function of oxygen flow rate were observed. With low resistivity and high mobility values, the films prepared at oxygen flow rate of 8 sccm are identified as suitable candidates for fabrication as absorber layer in solar cell devices.

  18. 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.

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

    SciTech Connect

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

    1995-12-31

    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 (HP) 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.

  20. 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.

  1. 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.

  2. 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.

  3. Vacuum rated flow controllers for inert gas ion engines

    NASA Technical Reports Server (NTRS)

    Pless, L. C.

    1987-01-01

    Electrical propulsion systems which use a gas as a propellant require a gas flowmeter/controller which is capable of operating in a vacuum environment. The presently available instruments in the required flow ranges are designed and calibrated for use at ambient pressure. These instruments operate by heating a small diameter tube through which the gas is flowing and then sensing the change in temperature along the length of the tube. This temperature change is a function of the flow rate and the gas heat capacity. When installed in a vacuum, the change in the external thermal characteristics cause the tube to overheat and the temperature sensors are then operating outside their calibrated range. In addition, the variation in heat capacity with temperature limit the accuracy obtainable. These problems and the work in progress to solve them are discussed.

  4. Vacuum rated flow controllers for inert gas ion engines

    NASA Technical Reports Server (NTRS)

    Pless, L. C.

    1987-01-01

    Electrical propulsion systems which use a gas as a propellant require a gas flowmeter/controller which is capable of operating in a vacuum environment. The presently available instruments in the required flow ranges are designed and calibrated for use at ambient pressure. These instruments operate by heating a small diameter tube through which the gas is flowing and then sensing the change in temperature along the length of the tube. This temperature change is a function of the flow rate and the gas heat capacity. When installed in a vacuum, the change in the external thermal characteristics cause the tube to overheat and the temperature sensors are then operating outside their calibrated range. In addition, the variation in heat capacity with temperature limit the accuracy obtainable. These problems and the work in progress to solve them are discussed.

  5. Flow and criticality in the open cycle gas core.

    NASA Technical Reports Server (NTRS)

    Kunze, J. F.; Lofthouse, J. H.

    1971-01-01

    A series of flowing gas experiments using air, argon, and freon has been conducted in Idaho. The purpose is to study methods of obtaining flow patterns which would create maximum possible system reactivity consistent with an acceptably low uranium to coolant-gas loss ratio. These have been conducted on both ?two-dimensional' and truly three-dimensional spherical configurations of diameters 18 to 42 inches. The larger diameter is that proposed for a minimum cost flowing gas critical experiment, and the size extremes make extrapolations to the large 6 and 8 foot diameter configurations more reliable. Results show that large enough inner gas (fuel) volume fractions can be achieved to attain criticality.

  6. 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.

  7. Internal flows of relevance to gas-turbines

    NASA Astrophysics Data System (ADS)

    McGuirk, J. J.; Whitelaw, J. H.

    An attempt is made to formulate the best combination of equations, numerical discretization, and turbulence modeling assumptions for internal aerodynamic flows relevant to gas turbines. Typical of the problems treated are the solution of the three-dimensional, time-averaged Navier-Stokes equations for laminar and turbulent flow in 90-deg bends, and the relative advantages obtainable from parabolized forms in bends, in S-type intake ducts, in turbine blade passages, and in forced mixers. In the present discussion of the influence of numerical assumptions on the calculation of isothermal flow in gas turbine combustors, emphasis is given to the assessment and removal of numerical errors.

  8. 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.

  9. 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.

  10. 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.

  11. Droplet breakup in accelerating gas flows. Part 1: Primary atomization

    NASA Technical Reports Server (NTRS)

    Zajac, L. J.

    1973-01-01

    An experimental study of the effects of an accelerating gas flow on the atomization characteristics of liquid sprays was conducted. The sprays were produced by impinging two liquid jets. The liquid was molten wax, while the gas was nitrogen. The use of molten wax allowed for a quantitative measure of the resulting dropsize distribution. The effects of the accelerating gas flow on the formation of the spray were examined. The results of this study indicate that the parameters that most affect the resulting dropsize are the injector parameters of orifice diameter and injection velocity, the maximum gas velocity, and the distance from the injector face at which the maximum gas velocity is attained. Empirical correlations for both the mass median dropsize and the dropsize distribution are presented. These correlations can be readily incorporated into existing computer codes for the purpose of calculating rocket engine combustion performance.

  12. 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.

  13. 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.

  14. 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 .

  15. 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.

  16. Use of greatly-reduced gas flows in flow-modulated comprehensive two-dimensional gas chromatography-mass spectrometry.

    PubMed

    Tranchida, Peter Q; Franchina, Flavio A; Dugo, Paola; Mondello, Luigi

    2014-09-12

    The present research is specifically based on the use of greatly-reduced gas flows, in flow-modulator (FM) comprehensive two-dimensional gas chromatography systems. In particular, focus of the present research is directed to FM devices characterized by an accumulation stage, and a much briefer re-injection step. It has been widely accepted that the operation of such FM systems requires high gas flows (≥20mL/min), to re-inject the gas-phase contents of sample (or accumulation) loops, onto the second column. On the contrary, it will be herein demonstrated that much lower gas flows (≈ 6-8mL/min) can efficiently perform the modulation step of re-injection. The possibility of using such improved operational conditions is given simply by a fine optimization of the processes of accumulation and re-injection. The application of lower gas flows not only means that second-dimension separations are carried out under better analytical conditions, but, even more importantly, greatly reduces problems which arise when using mass spectrometry (i.e., sensitivity and instrumental pumping capacity).

  17. Instabilities in granular gas-solid flows

    NASA Astrophysics Data System (ADS)

    Gómez González, Rubén; Garzó, Vicente

    2017-04-01

    A linear stability analysis of the hydrodynamic equations with respect to the homogeneous cooling state is performed to study the conditions for stability of a suspension of solid particles immersed in a viscous gas. The dissipation in such systems arises from two different sources: inelasticity in particle collisions and viscous friction dissipation due to the influence of the gas phase on the solid particles. The starting point is a suspension model based on the (inelastic) Enskog kinetic equation. The effect of the interstitial gas phase on the dynamics of grains is modeled though a viscous drag force. The study is carried out in two different steps. First, the transport coefficients of the system are obtained by solving the Enskog equation by means of the Chapman-Enskog method up to first order in spatial gradients. Explicit expressions for the Navier-Stokes transport coefficients are obtained in terms of the volume fraction, the coefficient of restitution and the friction coefficient characterizing the amplitude of the external force. Once the transport properties are known, then the corresponding linearized hydrodynamic equations are solved to get the dispersion relations. In contrast to previous studies (Garzó et al 2016 Phys. Rev. E 93 012905), the hydrodynamic modes are analytically obtained as functions of the parameter space of the system. For a d-dimensional system, as expected linear stability shows d  -  1 transversal (shear) modes and a longitudinal ‘heat’ mode to be unstable with respect to long enough wavelength excitations. The results also show that the main effect of the gas phase is to decrease the value of the critical length L c (beyond which the system becomes unstable) with respect to its value for a dry granular fluid. Comparison with direct numerical simulations for L c shows a qualitative good agreement for conditions of practical interest.

  18. Gas permeability and flow characterization of simulated lunar regolith

    NASA Astrophysics Data System (ADS)

    Toutanji, Houssam; Goff, Christopher M.; Ethridge, Edwin; Stokes, Eric

    2012-04-01

    Recent discoveries of water ice trapped within lunar topsoil (regolith) have placed a new emphasis on the recovery and utilization of water for future space exploration. Upon heating the lunar ice to sublimation, the resulting water vapor could theoretically transmit through the lunar regolith, to be captured on the surface. As the permeability of lunar regolith is essential to this process, this paper seeks to experimentally determine the permeability and flow characteristics of various gas species through simulated lunar regolith (SLR). Two different types of SLR were compacted and placed into the permeability setup to measure the flow-rate of transmitted gas through the sample. Darcy's permeability constant was calculated for each sample and gas combination, and flow characteristics were determined from the results. The results show that Darcy's permeability constant varies with SLR compaction density, and identified no major difference in permeable flow between the several tested gas species. Between the two tested SLR types, JSC-1A was shown to be more permeable than NU-LHT under similar conditions. In addition, a transition zone was identified in the flow when the gas pressure differential across the sample was less than ˜40 kPa.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Integrable geodesic flows and super polytropic gas equations

    NASA Astrophysics Data System (ADS)

    Guha, Partha

    2003-06-01

    The polytropic gas equations are shown to be the geodesic flows with respect to an L2 metric on the semidirect product space Diff( S1)⊙ C∞( S1), where Diff( S1) is the group of orientation preserving diffeomorphisms of the circle. We also show that the N=1 supersymmetric polytropic gas equation constitute an integrable geodesic flow on the extended Neveu-Schwarz space. Recently other kinds of supersymmetrizations have been studied vigorously in connection with superstring theory and are called supersymmetric-B (SUSY-B) extension. In this paper we also show that the SUSY-B extension of the polytropic gas equation form a geodesic flow on the extension of the Neveu-Schwarz space.

  4. Cold molecular gas in cooling flow clusters of galaxies

    NASA Astrophysics Data System (ADS)

    Salomé, P.; Combes, F.

    2003-12-01

    The results of a CO line survey in central cluster galaxies with cooling flows are presented. Cold molecular gas is detected with the IRAM 30 m telescope, through CO(1-0) and CO(2-1) emission lines in 6-10 among 32 galaxies. The corresponding gas masses are between 3*E8 and 4*E10 Msun. These results are in agreement with recent CO detections by \\cite{Edg01}. A strong correlation between the CO emission and the Hα luminosity is also confirmed. Cold gas exists in the center of cooling flow clusters and these detections may be interpreted as evidence of the long searched for very cold residual of the hot cooling gas. Tables 1-4 are also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/412/657

  5. Multiscale simulation of non-isothermal microchannel gas flows

    NASA Astrophysics Data System (ADS)

    Patronis, Alexander; Lockerby, Duncan A.

    2014-08-01

    This paper describes the development and application of an efficient hybrid continuum-molecular approach for simulating non-isothermal, low-speed, internal rarefied gas flows, and its application to flows in Knudsen compressors. The method is an extension of the hybrid continuum-molecular approach presented by Patronis et al. (2013) [4], which is based on the framework originally proposed by Borg et al. (2013) [3] for the simulation of micro/nano flows of high aspect ratio. The extensions are: 1) the ability to simulate non-isothermal flows; 2) the ability to simulate low-speed flows by implementing a molecular description of the gas provided by the low-variance deviational simulation Monte Carlo (LVDSMC) method; and 3) the application to three-dimensional geometries. For the purposes of validation, the multiscale method is applied to rarefied gas flow through a periodic converging-diverging channel (driven by an external acceleration). For this flow problem it is computationally feasible to obtain a solution by the direct simulation Monte Carlo (DSMC) method for comparison: very close agreement is observed. The efficiency of the multiscale method, allows the investigation of alternative Knudsen-compressor channel configurations to be undertaken. We characterise the effectiveness of the single-stage Knudsen-compressor channel by the pressure drop that can be achieved between two connected reservoirs, for a given temperature difference. Our multiscale simulations indicate that the efficiency is surprisingly robust to modifications in streamwise variations of both temperature and cross-sectional geometry.

  6. Hybrid continuum-molecular modelling of multiscale internal gas flows

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  9. 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.

  10. 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.

  11. Study of Mixed Collisionality Gas Flow in the VASIMR Thruster

    NASA Astrophysics Data System (ADS)

    Batishchev, Oleg; Molvig, Kim

    2000-11-01

    The degree of gas ionization in the VASIMR plasma thruster [1] is about one percent. This allows separating of the gas propellant flow from the plasma dynamics. The Knudsen number of the hydrogen (deuterium) or helium gas flow in a system of pipes of varying diameter falls into the .2-5 range. This indicates that the kinetic approach is required. First we present results from 1D hybrid Poiseuille-Knudsen model for viscous - free molecular pipe flow [2]. We compare simulation results to the experimental measurements. Next we study effects of (i) internal baffles to assist the retaining of the propellant, and (ii) gas pre-heating. Finally, we describe an extension of our 1D2V fully kinetic finite volume method [3] to a semi-collisional gas flow simulation. [1] F. Chang-Díaz et al., Bulletin of APS, 44 (1999) 99. [2] O. Batishchev and K. Molvig, AIAA 2000-3754 paper (2000). [3] Batishchev O. et al., J. Plasma Phys. 61 (1999) 347.

  12. 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.

  13. Structural support bracket for gas flow path

    SciTech Connect

    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.

  14. 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.

  15. Two parametric flow measurement in gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Chen, C.; Xu, Y.; Zhao, Z.

    The importance and current development of two parametric measurement during two-phase flow are briefly reviewed in this paper. Gas-liquid two-phase two parametric metering experiments were conducted by using an oval gear meter and a sharp edged orifice mounted in series in a horizontal pipe. Compressed air and water were used as gas and liquid phases respectively. The correlations, which can be used to predict the total flow rate and volumetric quality of two-phase flow or volumetric flow rate of each phase, have also been proposed in this paper. Comparison of the calculated values of flow rate of each phase from the correlations with the test data showed that the root mean square fractional deviation for gas flow rate is 2.9 percent and for liquid flow rate 4.4 percent. The method proposed in this paper can be used to measure the gas and liquid flow rate in two-phase flow region without having to separate the phases.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. 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.

  18. 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.

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

    SciTech Connect

    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.

  20. Filter-matrix lattice Boltzmann model for microchannel gas flows.

    PubMed

    Zhuo, Congshan; Zhong, Chengwen

    2013-11-01

    The lattice Boltzmann method has been shown to be successful for microscale gas flows, and it has attracted significant research interest. In this paper, the recently proposed filter-matrix lattice Boltzmann (FMLB) model is first applied to study the microchannel gas flows, in which a Bosanquet-type effective viscosity is used to capture the flow behaviors in the transition regime. A kinetic boundary condition, the combined bounce-back and specular-reflection scheme with the second-order slip scheme, is also designed for the FMLB model. By analyzing a unidirectional flow, the slip velocity and the discrete effects related to the boundary condition are derived within the FMLB model, and a revised scheme is presented to overcome such effects, which have also been validated through numerical simulations. To gain an accurate simulation in a wide range of Knudsen numbers, covering the slip and the entire transition flow regimes, a set of slip coefficients with an introduced fitting function is adopted in the revised second-order slip boundary condition. The periodic and pressure-driven microchannel flows have been investigated by the present model in this study. The numerical results, including the velocity profile and the mass flow rate, as well as the nonlinear pressure distribution along the channel, agree fairly well with the solutions of the linearized Boltzmann equation, the direct simulation Monte Carlo results, the experimental data, and the previous results of the multiple effective relaxation lattice Boltzmann model. Also, the present results of the velocity profile and the mass flow rate show that the present model with the fitting function can yield improved predictions for the microchannel gas flow with higher Knudsen numbers in the transition flow regime.

  1. Opposed-flow ignition and flame spread over melting polymers with Navier-Stokes gas flow

    NASA Astrophysics Data System (ADS)

    Zheng, Guanyu; Wichman, Indrek S.; Bénard, André

    2002-06-01

    A numerical model is constructed to predict transient opposed-flow flame spread behaviour in a channel flow over a melting polymer. The transient flame is established by initially applying a high external radiation heat flux to the surface. This is followed by ignition, transition and finally steady opposed-flow flame spread. The physical phenomena under consideration include the following: gas phase: channel flow, thermal expansion and injection flow from the pyrolyzed fuel; condensed phase: heat conduction, melting, and discontinuous thermal properties (heat capacity and thermal conductivity) across the phase boundary; gas-condensed phase interface: radiation loss. There is no in-depth gas radiation absorption in the gas phase. It is necessary to solve the momentum, species, energy and continuity equations in the gas along with the energy equation(s) in the liquid and solid. Agreement is obtained between the numerical spread rate and a flame spread formula. The influence of the gas flow is explored by comparing the Navier-Stokes (NS) and Oseen (OS) models. An energy balance analysis describes the flame-spread mechanism in terms of participating heat transfer mechanisms.

  2. Resonance Line Formation in Moving Gas Flows with High Porosity

    NASA Astrophysics Data System (ADS)

    Shulman, S. G.

    2017-06-01

    The formation of resonance lines in gas flows generated by interactions of circumstellar gas with a star's magnetosphere is examined. An effective method is proposed for calculating these lines when the magnetospheric wind is highly porous. The resonance sodium lines observed in the spectrum of UX Ori type star RZ Psc are modelled as an example. It is shown that the narrow absorptions observed in the short wavelength wings of these lines can be formed by scattering of the star's radiation in two gas jets that are semitransparent at the line frequencies when they cross the line of sight.

  3. Analytical treatment of gas flows through multilayer insulation, project 1

    NASA Technical Reports Server (NTRS)

    Lin, J. T.

    1972-01-01

    A theoretical investigation of gas flow inside a multilayer insulation system was made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was also investigated. It was shown that when the relaxation time is less than the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given and comparisons with experimental data were made.

  4. Gas flow in a stratified porous medium with crossflow

    NASA Astrophysics Data System (ADS)

    Sun, Hedong; Gao, Chengtai; Qian, Huanqun; Zhou, Fangde

    2002-02-01

    A new model called semi-permeable wall model is presented for multilayer gas reservoir. The model is used to study the influence of crossflow on pressure transient well tests and other single-phase flow problems. It is suggested here to use this model to approximate the actual multilayer gas reservoir, so that the problem is greatly simplified mathematically. Its differential equation is established here for multilayer gas reservoirs, and is linearized by normalized pseudo pressure and pseudo time. Simulation program is developed by finite-difference method when all layers are perforated. The feature of wellbore pressure and rate is clarified by analyzing the results of numerical simulation.

  5. 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.

  6. A numerical simulation of flows around a deformable gas bubble

    NASA Astrophysics Data System (ADS)

    Sugano, Minoru; Ishii, Ryuji; Morioka, Shigeki

    1991-12-01

    A numerical simulation of flows around a (deformable) gas bubble rising through an incompressible viscous fluid was carried out on a supercomputer Fujitsu VP2600 at Data Processing Center of Kyoto University. The solution algorithm is a modified Marker And Cell (MAC) method. For the grid generation, an orthogonal mapping proposed by Ryskin and Leal was applied. it is assumed that the shape of the bubble and the flow field are axisymmetric.

  7. 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.

  8. 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.

  9. 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.

  10. Chemical modification of sputtered amorphous-carbon surfaces

    NASA Astrophysics Data System (ADS)

    Leezenberg, Pieter B.; Johnston, William H.; Tyndall, George W.

    2001-03-01

    Methods to chemically passivate the surfaces of amorphous-carbon films (a-C) produced by dc magnetron sputtering were studied. The chemical composition of carbon surfaces produced via sputtering are dependent upon the environment to which the carbon is exposed immediately following deposition. When the sputtered film is vented to ambient conditions, free radicals produced at the surface during the deposition process are quenched by reaction with oxygen and/or water to form an oxidized, hydrophilic surface. If the sputtered carbon film is, however, exposed to a reactive gas prior to venting to ambient, the chemical nature of the resulting surface can be modified substantially. Specifically, a less highly oxidized and much more hydrophobic carbon surface is produced when the surface free radicals are quenched via either an addition reaction (demonstrated with a fluorinated olefin) or a hydrogen abstraction reaction (demonstrated with two alkyl amines). Chemical modification of amorphous-carbon films can also be accomplished by performing the sputtering in a reactive plasma formed from mixtures of argon with molecular hydrogen, amines, and perfluorocarbons. The elemental composition of these films, and the relative reactivity of the surfaces formed, were investigated via x-ray photoelectron spectroscopy and contact-angle goniometry, respectively. In the case of sputtering with a mixture of argon and hydrogen, increasing the hydrogen flow results in an increase in the amount of hydrogen incorporated into the carbon film and a decrease in the surface free energy. Sputtering in diethylamine produces an amorphous-carbon film into which nitrogen is incorporated. The free energies of the a-C:N surfaces produced in this process are similar to those of the a-C:H films. Sputtering in a fluorocarbon vapor results in the incorporation of fluorine into the film structure and the formation of very low free-energy surfaces. Increasing the concentration of the fluorocarbon in the

  11. Statistical parameter characteristics of gas-phase fluctuations for gas-liquid intermittent flow

    SciTech Connect

    Matsui, G.; Monji, H.; Takaguchi, M.

    1995-09-01

    This study deals with theoretical analysis on the general behaviour of statistical parameters of gas-phase fluctuations and comparison of statistical parameter characteristics for the real void fraction fluctuations measured with those for the wave form modified the real fluctuations. In order to investigate the details of the relation between the behavior of the statistical parameters in real intermittent flow and analytical results obtained from information on the real flow, the distributions of statistical parameters for general fundamental wave form of gas-phase fluctuations are discussed in detail. By modifying the real gas-phase fluctuations to a trapezoidaly wave, the experimental results can be directly compared with the analytical results. The analytical results for intermittent flow show that the wave form parameter, and the total amplitude of void fraction fluctuations, affects strongly on the statistical parameter characteristics. The comparison with experiment using nitrogen gas-water intermittent flow suggests that the parameters of skewness and excess may be better as indicators of flow pattern. That is, the macroscopic nature of intermittent flow can be grasped by the skewness and the excess, and the detailed flow structure may be described by the mean and the standard deviation.

  12. Design and Uncertainty Analysis for a PVTt Gas Flow Standard

    PubMed Central

    Wright, John D.; Johnson, Aaron N.; Moldover, Michael R.

    2003-01-01

    A new pressure, volume, temperature, and, time (PVTt) primary gas flow standard at the National Institute of Standards and Technology has an expanded uncertainty (k = 2) of between 0.02 % and 0.05 %. The standard spans the flow range of 1 L/min to 2000 L/min using two collection tanks and two diverter valve systems. The standard measures flow by collecting gas in a tank of known volume during a measured time interval. We describe the significant and novel features of the standard and analyze its uncertainty. The gas collection tanks have a small diameter and are immersed in a uniform, stable, thermostatted water bath. The collected gas achieves thermal equilibrium rapidly and the uncertainty of the average gas temperature is only 7 mK (22 × 10−6 T). A novel operating method leads to essentially zero mass change in and very low uncertainty contributions from the inventory volume. Gravimetric and volume expansion techniques were used to determine the tank and the inventory volumes. Gravimetric determinations of collection tank volume made with nitrogen and argon agree with a standard deviation of 16 × 10−6 VT. The largest source of uncertainty in the flow measurement is drift of the pressure sensor over time, which contributes relative standard uncertainty of 60 × 10−6 to the determinations of the volumes of the collection tanks and to the flow measurements. Throughout the range 3 L/min to 110 L/min, flows were measured independently using the 34 L and the 677 L collection systems, and the two systems agreed within a relative difference of 150 × 10−6. Double diversions were used to evaluate the 677 L system over a range of 300 L/min to 1600 L/min, and the relative differences between single and double diversions were less than 75 × 10−6. PMID:27413592

  13. The evolution of cooling flows. I - Self-similar cluster flows. [of gas in intergalactic medium

    NASA Technical Reports Server (NTRS)

    Chevalier, Roger A.

    1987-01-01

    The evolution of a cooling flow from an initial state of hydrostatic equilibrium in a cluster of galaxies is investigated. After gas mass and energy are injected into the cluster at an early phase, the gas approaches hydrostatic equilibrium over most of the cluster and cooling becomes important in the dense central regions. As time passes, cooling strongly affects an increasing amount of gas. The effects of mass removal from the flow, the inclusion of magnetic or cosmic-ray pressure, and heat conduction are considered individually.

  14. 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.

  15. Fast Gas Replacement in Plasma Process Chamber by Improving Gas Flow Pattern

    NASA Astrophysics Data System (ADS)

    Morishita, Sadaharu; Goto, Tetsuya; Akutsu, Isao; Ohyama, Kenji; Ito, Takashi; Ohmi, Tadahiro

    2009-01-01

    The precise and high-speed alteration of various gas species is important for realizing precise and well-controlled multiprocesses in a single plasma process chamber with high throughput. The gas replacement times in the replacement of N2 by Ar and that of H2 by Ar are measured in a microwave excited high-density and low electron-temperature plasma process chamber at various working pressures and gas flow rates, incorporating a new gas flow control system, which can avoid overshoot of the gas pressure in the chamber immediately after the valve operation, and a gradational lead screw booster pump, which can maintain excellent pumping capability for various gas species including lightweight gases such as H2 in a wide pressure region from 10-1 to 104 Pa. Furthermore, to control the gas flow pattern in the chamber, upper ceramic shower plates, which have thousands of very fine gas injection holes (numbers of 1200 and 2400) formed with optimized allocation on the plates, are adopted, while the conventional gas supply method in the microwave-excited plasma chamber uses many holes only opened at the sidewall of the chamber (gas ring). It has been confirmed that, in the replacement of N2 by Ar, a short replacement time of approximately 1 s in the cases of 133 and 13.3 Pa and approximately 3 s in the case of 4 Pa can be achieved when the upper shower plate has 2400 holes, while a replacement time longer than approximately 10 s is required for all pressure cases where the gas ring is used. In addition, thanks to the excellent pumping capability of the gradational lead screw booster pump for lightweight gases, it has also been confirmed that the replacement time of H2 by Ar is almost the same as that of N2 by Ar.

  16. Turbulence modeling of gas-solid suspension flows

    NASA Technical Reports Server (NTRS)

    Chen, C. P.

    1988-01-01

    The purpose here is to discuss and review advances in two-phase turbulent modeling techniques and their applications in various gas-solid suspension flow situations. In addition to the turbulence closures, heat transfer effect, particle dispersion and wall effects are partially covered.

  17. 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...

  18. Melt removal mechanism by transverse gas flow during laser irradiation

    NASA Astrophysics Data System (ADS)

    Wei, Cheng-hua; Zhu, Yong-xiang; Zhou, Meng-lian; Ma, Zhi-liang; Wu, Tao-tao

    2017-05-01

    To determine the mechanism of melt removal by transverse gas flow, a lateral visualization technique of hydrodynamics on melt pool was developed and experimental apparatus were built. The intensity distribution of the focused beam was confirmed to be in top-hat shape with the 15mm×40mm rectangular. The interface of liquid-solid and free surface of molten metal was observed by a high velocity video camera with acquisition rate of 1kHz. Gas flow blew from left to right and the velocity varied from 15m/s to 90m/s to investigate the evolution of hydrodynamics. Experiment results showed that surface wave was generated at the initial stage and molten metal was removed out from the melt pool by shear stress. When some amount molten metal was removed from melt pool, gas flow separated at the leading edge and reattaches downstream of melt pool. Thus a stagnation point was formed at the downstream edge and a recirculation zone was generated on the left side of stagnation. With recirculation gas flow constrain, the molten metal only can be entrained into main stream and then be swept away. The molten material was removed out by shear stress on the right side of stagnation.

  19. 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.

  20. Computer program determines gas flow rates in piping systems

    NASA Technical Reports Server (NTRS)

    Franke, R.

    1966-01-01

    Computer program calculates the steady state flow characteristics of an ideal compressible gas in a complex piping system. The program calculates the stagnation and total temperature, static and total pressure, loss factor, and forces on each element in the piping system.

  1. Long arc stabilities with various arc gas flow rates

    NASA Astrophysics Data System (ADS)

    Maruyama, K.; Takeda, K.; Sugimoto, M.; Noguchi, Y.

    2014-11-01

    A new arc torch for use in magnetically driven arc device was developed with a commercially available TIG welding arc torch. The torch has a water-cooling system to the torch nozzle and has a nozzle nut to supply a swirling-free plasma gas flow. Its endurance against arc thermal load is examined. Features of its generated arc are investigated.

  2. 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.

  3. Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

    NASA Astrophysics Data System (ADS)

    Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

    2016-12-01

    Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

  4. 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 ...

  5. 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 ...

  6. 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.

  7. Navier-Stokes simulation of real gas flows in nozzles

    NASA Technical Reports Server (NTRS)

    Nagaraj, N.; Lombard, C. K.

    1987-01-01

    Air flow in a hypersonic nozzle causes real gas effects due to reaction among the species constituting air. Such reactions may be in chemical equilibrium or in chemical nonequilibrium. Here using the CSCM upwind scheme for the compressible Navier-Stokes equations, the real gas flowfield in an arcjet nozzle is computed for both the equilibrium case and the nonequilibrium case. A hypersonic nozzle flow arising from a pebble bed heated plenum is also computed for the equilibrium situation. Between the equilibrium cases, the chemistry is treated by two different schemes and comments are made as to computational complexity. For the nonequilibrium case, a full set of seventeen reactions and full implicit coupling of five species with gasdynamics is employed to compute the flowfield. For all cases considered here the gas is assumed to be a calorically imperfect mixture of ideal gases in thermal equilibrium.

  8. Navier-Stokes simulation of real gas flows in nozzles

    NASA Technical Reports Server (NTRS)

    Nagaraj, N.; Lombard, C. K.

    1987-01-01

    Air flow in a hypersonic nozzle causes real gas effects due to reaction among the species constituting air. Such reactions may be in chemical equilibrium or in chemical nonequilibrium. Here using the CSCM upwind scheme for the compressible Navier-Stokes equations, the real gas flowfield in an arcjet nozzle is computed for both the equilibrium case and the nonequilibrium case. A hypersonic nozzle flow arising from a pebble bed heated plenum is also computed for the equilibrium situation. Between the equilibrium cases, the chemistry is treated by two different schemes and comments are made as to computational complexity. For the nonequilibrium case, a full set of seventeen reactions and full implicit coupling of five species with gasdynamics is employed to compute the flowfield. For all cases considered here the gas is assumed to be a calorically imperfect mixture of ideal gases in thermal equilibrium.

  9. 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.

  10. Radial gas flow in the upper shaft and its influence on blast furnace performance

    SciTech Connect

    Beppler, E.; Kowalski, W.; Langner, K.; Wachsmuth, H.

    1996-12-31

    Knowledge of and control of gas flow in the upper shaft and over the blast furnace radius is an important factor for constant optimization of blast furnace performance in terms of fuel consumption and productivity. Radial gas flow in the blast furnace is generally controlled by the radial distribution of burden and coke. However, there are other influencing variables which determine radial gas flow, in particular central gas flow: (a) Increased sinter degradation displaces the cohesive zone downwards, constricting the gas flow between the dead man and the cohesive zone. This hinders central gas flow. (b) Lower coke strengths also lead to deterioration in gas flow between the dead man and the cohesive zone and hence to decline in central gas flow. (c) Decreasing coke layers in the blast furnace hinder central gas flow. (d) Increasing coal injection rates produce higher coke degradation in the blast furnace and hence also hinder central gas flow. (e) High coal rates and lower CSR values lead to shortening of combustion zone, which hinders the gas flow to the blast furnace center. (f) Finally, increasing hot metal-slag levels divert the gas to the outside. As the significance of the question of the central gas flow is growing,and because radial gas flow at Thyssen Stahl AG can only be measured sporadically with an in-burden probe, an inclined probe (inclination 35{degree}) just above the stock line was developed for simultaneous temperature measurement and gas sampling at 9 points along the radius.

  11. Numerical investigations of flow structure in gas turbine shroud gap

    NASA Astrophysics Data System (ADS)

    Wasilczuk, F.; Flaszyński, P.; Doerffer, P.

    2016-10-01

    The structure of the flow in the labyrinth sealing of an axial gas turbine was investigated by means of numerical simulations. Additionally, the flow structure for two- and three-dimensional axisymmetric models was compared. The porous disc as a model for the pressure drop relevant to the obtained in the cascade was proposed and tested. Several flow structure features existing in the sealing cavities are investigated: vortical structure and separation bubble on the rib and the correlation between the pressure drop and the clearance size. The carried out investigations indicate that the innovation aimed at decreasing the leakage flow through implementation of the flow control devices is possible. Furthermore the comparison between 2D and 3D models shows good agreement, thus application of less demanding 2D model introduces negligible differences. It is shown that the proposed porous disc model applied to mimic pressure drop in cascade can be effectively used for rotor blade sealing simulations.

  12. 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.

  13. 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.

  14. Droplet breakup in accelerating gas flows. Part 2: Secondary atomization

    NASA Technical Reports Server (NTRS)

    Zajac, L. J.

    1973-01-01

    An experimental investigation to determine the effects of an accelerating gas flow on the atomization characteristics of liquid sprays was conducted. The sprays were produced by impinging two liquid jets. The liquid was molten wax and the gas was nitrogen. The use of molten wax allowed for a quantitative measure of the resulting dropsize distribution. The results of this study, indicate that a significant amount of droplet breakup will occur as a result of the action of the gas on the liquid droplets. Empirical correlations are presented in terms of parameters that were found to affect the mass median dropsize most significantly, the orifice diameter, the liquid injection velocity, and the maximum gas velocity. An empirical correlation for the normalized dropsize distribution is also presented. These correlations are in a form that may be incorporated readily into existing combustion model computer codes for the purpose of calculating rocket engine combustion performance.

  15. Analysis of gas flow through a multilayer insulation system.

    NASA Technical Reports Server (NTRS)

    Lin, J. T.

    1973-01-01

    A theoretical investigation of gas flow inside a multilayer insulation system has been made for the case of the broadside pumping process. A set of simultaneous first-order differential equations for the temperature and pressure of the gas mixture was obtained by considering the diffusion mechanism of the gas molecules through the perforations on the insulation layers. A modified Runge-Kutta method was used for numerical experiment. The numerical stability problem was investigated. It has been shown that when the relaxation time is small compared with the time period over which the gas properties change appreciably, the set of differential equations can be replaced by a set of algebraic equations for solution. Numerical examples were given and comparison with experimental data was made.

  16. 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

  17. Studies on the room temperature growth of nanoanatase phase TiO2 thin films by pulsed dc magnetron with oxygen as sputter gas

    NASA Astrophysics Data System (ADS)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-03-01

    The anatase phase titanium dioxide (TiO2) thin films were deposited at room temperature by pulsed dc magnetron sputtering using pure oxygen as sputter gas. The structural, optical, electrical, and electrochromic properties of the films have been studied as a function of oxygen pressure in the chamber. The x-ray diffraction results indicate that the films grown above 4.5×10-2mbar are nanocrystalline (grain size of 28-43nm) with anatase phase. The films deposited at the chamber pressure of 7.2×10-2mbar are found to be highly crystalline with a direct optical band gap of 3.40eV, refractive index of 2.54 (at λ =400nm), and work function of 4.77eV (determined by the Kelvin probe measurements). From the optical emission spectra of the plasma and transport of ions in matter calculations, we find that the crystallization of TiO2 at room temperature is due to the impingement of electrons and ions on the growing films. Particularly, the negative oxygen ions reflected from the target by "negative ion effects" and the enhanced density of TiO, TiO +, TiO2+, and O2+ particles in the plasma are found to improve the crystallization even at a relatively low temperature. From an application point of view, the film grown at 7.2×10-2mbar was studied for its electrochromic properties by protonic intercalation. It showed good electrochromic behavior with an optical modulation of ˜45%, coloration efficiency of 14.7 cm2C-1, and switching time (tc) of 50s for a 2×2 cm2 device at λ =633nm.

  18. Magnetron sputtering system for coatings deposition with activation of working gas mixture by low-energy high-current electron beam

    NASA Astrophysics Data System (ADS)

    Gavrilov, N. V.; Kamenetskikh, A. S.; Men'shakov, A. I.; Bureyev, O. A.

    2015-11-01

    For the purposes of efficient decomposition and ionization of the gaseous mixtures in a system for coatings deposition using reactive magnetron sputtering, a low-energy (100-200 eV) high-current electron beam is generated by a grid-stabilized plasma electron source. The electron source utilizes both continuous (up to 20 A) and pulse-periodic mode of discharge with a self-heated hollow cathode (10-100 A; 0.2 ms; 10-1000 Hz). The conditions for initiation and stable burning of the high-current pulse discharge are studied along with the stable generation of a low-energy electron beam within the gas pressure range of 0.01 - 1 Pa. It is shown that the use of the electron beam with controllable parameters results in reduction of the threshold values both for the pressure of gaseous mixture and for the fluxes of molecular gases. Using such a beam also provides a wide range (0.1-10) of the flux density ratios of ions and sputtered atoms over the coating surface, enables an increase in the maximum pulse density of ion current from plasma up to 0.1 A, ensures an excellent adhesion, optimizes the coating structure, and imparts improved properties to the superhard nanocomposite coatings of (Ti,Al)N/a-Si3N4 and TiC/-a-C:H. Mass-spectrometric measurements of the beam-generated plasma composition proved to demonstrate a twofold increase in the average concentration of N+ ions in the Ar-N2 plasma generated by the high-current (100 A) pulsed electron beam, as compared to the dc electron beam.

  19. Fundamentals of multiphase, gas-solid and gas-liquid flows in porous media

    NASA Astrophysics Data System (ADS)

    Mazaheri, Ali Reza

    This thesis is concerned with fundamentals and applications of multiphase and particulate flows. The study contains three parts covering gas-liquid flows through porous media, gas-solid flows and Chemical-Mechanical Polishing (CMP). A continuum model for multiphase fluid flows through poro-elastic media is developed. It is shown that the present theory leads to the extended Darcy's law and contains, as its special case, Biot's theory of saturated poro-elastic media. The capillary pressure formulation derived from the new model is used and the equation governing the evolution of the saturation and its temporal variation in porous media is derived. The resulting nonlinear diffusion equation is then solved numerically. The results show that the capillary hysteresis occurs when the temporal variation of saturation is included. Application of the developed model to CO2 sequestration is discussed. Computer simulations of dilute Gas-Solid flows in complex geometry regions are studied. A procedure for handling particle trajectory analysis in unstructured grid is developed. Examples of particle transport and removal in human lung and hot-gas cleaning systems are presented. The simulation results for the human lung show that the capture efficiency is affected by the turbulence in the upper three bifurcation airways. Computer simulations of gas-solid flows in hot-gas cleaning for a demonstration scale filtration system is studied in details. Alternative designs of the filter vessel are proposed. The corresponding vessel performance are numerically simulated. Chemical mechanical polishing (CMP) has become critical to the fabrication of advanced multilevel integrated circuit in microelectronic industry. The effect of course surface roughness of abrasive particles on the polishing rate in CMP is studied. The effects of slurry pH and double layer attraction and repulsion on chemical-mechanical polishing are also studied. It is shown that the slurry pH and colloidal forces

  20. Numerical simulations of high Knudsen number gas flows and microchannel electrokinetic liquid flows

    NASA Astrophysics Data System (ADS)

    Yan, Fang

    Low pressure and microchannel gas flows are characterized by high Knudsen numbers. Liquid flows in microchannels are characterized by non-conventional driving potentials like electrokinetic forces. The main thrust of the dissertation is to investigate these two different kinds of flows in gases and liquids respectively. High Knudsen number (Kn) gas flows were characterized by 'rarified' or 'microscale' behavior. Because of significant non-continuum effect, traditional CFD techniques are often inaccurate for analyzing high Kn number gas flows. The direct simulation Monte Carlo (DSMC) method offers an alternative to traditional CFD which retains its validity in slip and transition flow regimes. To validate the DSMC code, comparisons of simulation results with theoretical analysis and experimental data are made. The DSMC method was first applied to compute low pressure, high Kn flow fields in partially heated two dimensional channels. The effects of varying pressure, inlet flow and gas transport properties (Kn, Reynolds number, Re and the Prandtl number, Pr respectively) on the wall heat transfer (Nusselt number, Nu) were examined. The DSMC method was employed to explore mixing gas flows in two dimensional microchannels. Mixing of two gas streams (H2 and O2) was considered within a microchannel. The effect of the inlet-outlet pressure difference, the pressure ratio of the incoming streams and the accommodation coefficient of the solid wall on mixing length were all examined. Parallelization of a three-dimensional DSMC code was implemented using OpenMP procedure on a shared memory multi-processor computer. The parallel code was used to simulate 3D high Kn number Couette flow and the flow characteristics are found to be very different from their continuum counterparts. A mathematical model describing electrokinetically driven mass transport phenomena in microfabricated chip devices will also be presented. The model accounts for the principal physical phenomena affecting

  1. Parallel magnetic resonance imaging of gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Mueller, Christoph; Penn, Alexander; Pruessmann, Klaas P.

    2015-03-01

    Gas-liquids flows are commonly encountered in nature and industry. Experimental measurements of gas-liquid flows are challenging since such systems can be visually opaque and highly dynamic. Here we report the implementation of advanced magnetic resonance imaging (MRI) strategies allowing us to probe the dynamics (voidage and velocity measurements) of gas-liquid flows with ultra-fast acquisition speeds. Specifically, parallel MRI which exploits the spatial encoding capabilities of multiple receiver coils was implemented. To this end a tailored, 16 channels MR receive array was constructed and employed in the MR acquisition. A magnetic susceptibility matched gas-liquid system was set-up and used to probe the motion, splitting and coalescence of bubbles. The temporal and spatial resolution of our acquired data was 5 ms and 3.5 mm x 3.5 mm, respectively. The total field of view was 200 mm x 200 mm. We will conclude with an outlook of further possible advances in MRI that have the potential to reduce substantially the acquisition time, providing flexible gains in temporal and spatial resolution.

  2. Salinity independent measurement of gas volume fraction in oil/gas/water pipe flows

    PubMed

    Johansen; Jackson

    2000-10-01

    Dual mode densitometry is presented as a novel method of measuring the gas volume fraction in gas/oil/water pipe flows independent of the salinity of the water component. The different response in photoelectric attenuation and Compton scattering to changes in salinity is utilized. The total attenuation coefficient is found through traditional transmission measurements with a detector positioned outside the pipe wall diametrically opposite the source. The scatter response is measured with a second detector positioned somewhere between the source and the transmission detector. The feasibility of the method is demonstrated for homogeneously mixed flows.

  3. 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

  4. 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].

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

    SciTech Connect

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

    2016-07-19

    Nanocomposite TiAlBN (nc-TiAlBN) coatings were successfully deposited via RF magnetron sputtering by varying the nitrogen-to-total gas flow ratio (R{sub N}), and substrate temperature (T{sub S}). 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 % R{sub N}. As the nitrogen concentration decreases, boron concentration increased from 9 at.% to 16.17 at.%. and thus, increase the TiB{sub 2} phase within the coatings. The T{sub S}, however, showed no significant effect either on the crystallographic structure, grain size, or in the chemical composition of the deposited nc-TiAlBN coating.

  6. Optical instrumentation and study of gas-solid suspension flows

    SciTech Connect

    Ling, S.C.; Pao, H.P.

    1990-09-01

    A new technique and particle detecting system for the quantification of local fluid flow velocities, particle concentrations and size distributions in gas-solid suspension flows has been successfully developed and constructed. A new 2-inch diameter pneumatic-pipe test-loop facility for study of solids transport flows has been built and in operation. In order to check scaling law developed from the experimental results in the 2-inch pipe, a 4-inch pipe test-loop facility was also designed and constructed. In the past, the mechanics of suspended-solid flow have not been solved in a closed form due to the lack of a model for the turbulent field to pick up solid particles from the flow boundary. In this research project, we have identified the existence of micro-hairpin vortices as a major mechanism for the lifting of solid particles from the flow boundary. This permits one to formulate a realistic model. That is, the introduction of a particle source term in the governing transport equation for the suspended particles. The resultant solution predicts the correct critical flow conditions for the initial pickup of different sizes of solid particles and their subsequent concentrations in the flow field. 21 figs.

  7. Studies of internal sputtering in a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1975-01-01

    Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have beem measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power losses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

  8. Studies of internal sputtering in a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1975-01-01

    Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have been measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power loses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

  9. 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.

  10. 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%.

  11. 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.

  12. 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.

  13. 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

  14. Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates

    NASA Astrophysics Data System (ADS)

    Fang, Min; Xu, Ke-Jun; Zhu, Wen-Jiao; Shen, Zi-Wen

    2016-01-01

    Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

  15. Radial Gas Flows in Colliding Galaxies: Connecting Simulations and Observations

    NASA Astrophysics Data System (ADS)

    Iono, Daisuke; Yun, Min S.; Mihos, J. Christopher

    2004-11-01

    We investigate the detailed response of gas to the formation of transient and long-lived dynamical structures induced in the early stages of a disk-disk collision and identify observational signatures of radial gas inflow through a detailed examination of the collision simulation of an equal-mass bulge-dominated galaxy. Our analysis and discussion mainly focuses on the evolution of the diffuse and dense gas in the early stages of the collision, when the two disks are interacting but have not yet merged. Stars respond to the tidal interaction by forming both transient arms and long-lived m=2 bars, but the gas response is more transient, flowing directly toward the central regions within about 108 yr after the initial collision. The rate of inflow declines when more than half of the total gas supply reaches the inner few kiloparsecs, where the gas forms a dense nuclear ring inside the stellar bar. The average gas inflow rate to the central 1.8 kpc is ~7 Msolar yr-1 with a peak rate of 17 Msolar yr-1. Gas with high volume density is found in the inner parts of the postcollision disks at size scales close to the spatial resolution of the simulations, and this may be a direct result of shocks traced by the discontinuity in the gas velocity field. The evolution of gas in a bulgeless progenitor galaxy is also discussed, and a possible link to the ``chain galaxy'' population observed at high redshifts is inferred. The evolution of the structural parameters such as asymmetry and concentration of both stars and gas are studied in detail. Further, a new structure parameter (the compactness parameter K) that traces the evolution of the size scale of the gas relative to the stellar disk is introduced, and this may be a useful tracer to determine the merger chronology of colliding systems. Noncircular gas kinematics driven by the perturbation of the nonaxisymmetric structure can produce distinct emission features in the ``forbidden velocity quadrants'' of the position

  16. Flow behaviour and transitions in surfactant-laden gas-liquid vertical flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Chakraborty, Sourojeet; Matar, Omar; Markides, Christos

    2016-11-01

    The aim of this work is to elucidate the effect of surfactant additives on vertical gas-liquid counter-current pipe flows. Two experimental campaigns were undertaken, one with water and one with a light oil (Exxsol D80) as the liquid phase; in both cases air was used as the gaseous phase. Suitable surfactants were added to the liquid phase up to the critical micelle concentration (CMC); measurements in the absence of additives were also taken, for benchmarking. The experiments were performed in a 32-mm bore and 5-m long vertical pipe, over a range of superficial velocities (liquid: 1 to 7 m/s, gas: 1 to 44 m/s). High-speed axial- and side-view imaging was performed at different lengths along the pipe, together with pressure drop measurements. Flow regime maps were then obtained describing the observed flow behaviour and related phenomena, i.e., downwards/upwards annular flow, flooding, bridging, gas/liquid entrainment, oscillatory film flow, standing waves, climbing films, churn flow and dryout. Comparisons of the air-water and oil-water results will be presented and discussed, along with the role of the surfactants in affecting overall and detailed flow behaviour and transitions; in particular, a possible mechanism underlying the phenomenon of flooding will be presented. EPSRC UK Programme Grant EP/K003976/1.

  17. 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.

  18. Computational technology of multiscale modeling the gas flows in microchannels

    NASA Astrophysics Data System (ADS)

    Podryga, V. O.

    2016-11-01

    The work is devoted to modeling the gas mixture flows in engineering microchannels under conditions of many scales of computational domain. The computational technology of using the multiscale approach combining macro - and microscopic models is presented. At macrolevel the nature of the flow and the external influence on it are considered. As a model the system of quasigasdynamic equations is selected. At microlevel the correction of gasdynamic parameters and the determination of boundary conditions are made. As a numerical model the Newton's equations and the molecular dynamics method are selected. Different algorithm types used for implementation of multiscale modeling are considered. The results of the model problems for separate stages are given.

  19. 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.

  20. 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.

  1. 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.

  2. TRANSFLOW: An experimental facility for vacuum gas flows

    NASA Astrophysics Data System (ADS)

    Varoutis, S.; Giegerich, T.; Hauer, V.; Day, Chr

    2012-05-01

    The TRANSFLOW experimental facility represents a reliable tool for measuring the conductance of 1:1 scale components as typically used in vacuum systems in a wide range of the Knudsen number (e.g. 10-4<=Kn<=103). The main principle of this facility is the dynamic measurement of the pressure difference upstream and downstream of the duct by setting a constant mass flow rate through the test channel. Many experiments on fully developed and developing flows, based on long and short channels respectively, have been already completed and comparisons with corresponding numerical results have been successfully performed. It has been clearly proven that the TRANSFLOW experimental setup provides conductance results with overall uncertainty between 1 to 10% and it could be used as a benchmark facility for any new proposed scientific numerical method in rarefied gas dynamics and in the whole range of gas rarefaction.

  3. Continuous flow production of concentrated hyperpolarized xenon gas from a dilute xenon gas mixture by buffer gas condensation.

    PubMed

    Imai, Hirohiko; Yoshimura, Hironobu; Kimura, Atsuomi; Fujiwara, Hideaki

    2017-08-04

    We present a new method for the continuous flow production of concentrated hyperpolarized xenon-129 (HP (129)Xe) gas from a dilute xenon (Xe) gas mixture with high nuclear spin polarization. A low vapor pressure (i.e., high boiling-point) gas was introduced as an alternative to molecular nitrogen (N2), which is the conventional quenching gas for generating HP (129)Xe via Rb-Xe spin-exchange optical-pumping (SEOP). In contrast to the generally used method of extraction by freezing Xe after the SEOP process, the quenching gas separated as a liquid at moderately low temperature so that Xe was maintained in its gaseous state, allowing the continuous delivery of highly polarized concentrated Xe gas. We selected isobutene as the candidate quenching gas and our method was demonstrated experimentally while comparing its performance with N2. Isobutene could be liquefied and removed from the Xe gas mixture using a cold trap, and the concentrated HP (129)Xe gas exhibited a significantly enhanced nuclear magnetic resonance (NMR) signal. Although the system requires further optimization depending on the intended purpose, our approach presented here could provide a simple means for performing NMR or magnetic resonance imaging (MRI) measurements continuously using HP (129)Xe with improved sensitivity.

  4. Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering Deposition System

    DTIC Science & Technology

    2013-07-01

    either electrical or optical in nature. The electrical technique which is used for electron temperature and density measurement is Langmuir probe...But it has some remarkable problems [6]. Therefore, optical diagnostic methods have been developed. Optical emission spectroscopy (OES) has been...nitrogen gas to the total gas are adjusted on 10%, 20% and 30%. Each experiment continues for 40 min. During the experiments, OCEAN OPTICS spectrometer

  5. 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

  6. Pulsatile flow and gas transfer over arrays of cylinders

    NASA Astrophysics Data System (ADS)

    Chan, Kit Yan; Fujioka, Hideki; Grotberg, James B.

    2004-11-01

    In an artificial lung device, blood passes through arrays of porous microfibers and the gas transfer occurring across the fiber surfaces strongly depends on the flow field. Pulsatile flow distribution and gas transfer over arrays of porous microfibers (modeled as cylinders) are numerically simulated for both Newtonian and Casson fluids using Finite Volume method. Different arrangements of the cylinders: square array, rectangular array, staggered array are considered in this study. For some of the studies, the average x-velocity U(t) is described by U(t) = U0 ( 1 +A sin ( ω t) ) [1], where U0 is the time-average x-velocity, A is the amplitude of the oscillation, and ω is the frequency. For other studies, half of a cycle is described by [1] and half of the cycle U(t) = 0. The inclusion of a zero average velocity period in U(t) is physiologically a better description of the time-average velocity of blood exiting the heart. Interestingly, gas transfer increases when U(t) is described this way, due to the appearance of large vortices that enhance mixing. The existence, the size and the location of the recirculation zones are found to be controlled by array geometry and flow parameters. In general, conditions that enhance the gas transfer also at the same time increase the maximum flow resistance; such as the increase of the Reynolds number, the Womersley number, A, and cylinder density, with the exception of the increase of the yield stress for a Casson fluid. This work is supported by NIH: HL 69420.

  7. Gentle protein ionization assisted by high-velocity gas flow.

    PubMed

    Yang, Pengxiang; Cooks, R Graham; Ouyang, Zheng; Hawkridge, Adam M; Muddiman, David C

    2005-10-01

    Gentle protein electrospray ionization is achieved using the high-velocity gas flow of an air amplifier to improve desolvation in conventional ESI and generate intact folded protein ions in the gas phase. Comparisons are made between the ESI spectra of a number of model proteins, including ubiquitin, cytochrome c, lysozyme, and myoglobin, over a range of pH values under optimized conditions, with and without using an air amplifier to achieve high-velocity gas flow. Previously reported increased ion signals are confirmed. In addition, the peaks recorded using the air amplifier are shown to be narrower, corresponding to more complete desolvation. Significant changes in the charge-state distribution also are observed, with a shift to lower charge state at high-velocity flow. The relationship between the observed charge-state distribution and protein conformation was explored by comparing the charge-state shifts and the distributions of charge states for proteins that are or are not stable in their native conformations in low pH solutions. The data suggest retention of native or nativelike protein conformations using the air amplifier in all cases examined. This is explained by a mechanism in which the air amplifier rapidly creates small droplets from the original large ESI droplets and these microdroplets then desolvate without a significant decrease in pH, resulting in retention of the folded protein conformations. Furthermore, the holoform of ionized myoglobin is visible at pH 3.5, a much lower value than the minimum needed to see this form in conventional ESI. These results provide evidence for the importance of the conditions used in the desolvation process for the preservation of the protein conformation and suggest that the conditions achieved when using high-velocity gas flows to assist droplet evaporation and ion desolvation are much gentler than those in conventional ESI experiments.

  8. Flow and heat transfer for gas flowing in microchannels: a review

    NASA Astrophysics Data System (ADS)

    Rostami, A. A.; Mujumdar, A. S.; Saniei, N.

    Microchannels are currently being used in many areas and have high potential for applications in many other areas, which are considered realistic by experts. The application areas include medicine, biotechnology, avionics, consumer electronics, telecommunications, metrology, computer technology, office equipment and home appliances, safety technology, process engineering, robotics, automotive engineering and environmental protection. A number of these applications are introduced in this paper, followed by a critical review of the works on the flow and heat transfer for gas flowing in microchannels. The results show that the flow and heat transfer characteristics of a gas flowing in microchannels can not be adequately predicted by the theories and correlations developed for conventional sized channels. The results of theoretical and experimental works are discussed and summarized along with suggestions for future research directions.

  9. Stability of Buoyancy-Driven Gas Flow: Visualization of Coherent and Incoherent Gas Flow Patterns and Capillary Trapping

    NASA Astrophysics Data System (ADS)

    Geistlinger, H. W.; Samani, S.; Pohlert, M.; Jia, R.; Lazik, D.

    2009-12-01

    sequestration mechanisms. In order to investigate the stability of buoyancy-driven gas flow and the transition between coherent flow, incoherent flow, and their correlation to capillary trapping, we conducted high-resolution optical bench scale experiments. We observed a grain-size (dk) - and flow-rate (Q) dependent transition from incoherent to coherent flow. Based on core-annular flow (= cooperative pore-body filling), we propose a dynamic stability criterion that could describe our experimental results. Our experimental results for vertical gas flow support the experimental results by Lenormand et al. [1983] obtained for horizontal flow, if one takes into account that gravity leads to more unstable flow conditions. Our main results, which are in strong contradiction to the accepted conceptual model of the sloped aquifer, are: (1) Capillary Trapping can already occur during injection and at the front of the plume [Lazik et al., 2008] (2) Gas clusters or bubbles can be mobile (incoherent gas flow) and immobile (capillary trapping), and (3) Incoherent gas flow can not be described by a generalized Darcy law [Geistlinger et al., 2006, 2009].

  10. One-dimensional flows of an imperfect diatomic gas

    NASA Technical Reports Server (NTRS)

    1959-01-01

    With the assumptions that Berthelot's equation of state accounts for molecular size and intermolecular force effects, and that changes in the vibrational heat capacities are given by a Planck term, expressions are developed for analyzing one-dimensional flows of a diatomic gas. The special cases of flow through normal and oblique shocks in free air at sea level are investigated. It is found that up to a Mach number 10 pressure ratio across a normal shock differs by less than 6 percent from its ideal gas value; whereas at Mach numbers above 4 the temperature rise is considerable below and hence the density rise is well above that predicted assuming ideal gas behavior. It is further shown that only the caloric imperfection in air has an appreciable effect on the pressures developed in the shock process considered. The effects of gaseous imperfections on oblique shock-flows are studied from the standpoint of their influence on the life and pressure drag of a flat plate operating at Mach numbers of 10 and 20. The influence is found to be small. (author)

  11. 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.

  12. Surface-Gas Interaction Effects on Nanoscale Flows

    NASA Astrophysics Data System (ADS)

    Barisik, Murat; Beskok, Ali

    2011-11-01

    Three-dimensional molecular dynamics (MD) simulations of linear Couette flow of argon gas confined within nano-scale channels are investigated as a function of the surface-gas interaction strength ratio (ISR). Simulations are performed in the slip, transition and free molecular flow regimes by keeping the base pressure constant for different ISR cases. Near-wall gas density increases with increased ISR and eventually results in adsorption of argon on the surfaces. Although the velocity profiles agree with the kinetic theory predictions in the bulk of the channel, they show sudden increase in the near wall region, resulting in decreased velocity slip at the interface. High ISR values are shown to induce velocity stick. Increase in the ISR results in stronger surface-particle interactions. Hence, the surface virial becomes more dominant in the near wall region, resulting in increasingly anisotropic normal stresses. 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 shown to increase with increased ISR.

  13. 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.

  14. Study of interfacial behavior in cocurrent gas-liquid flows

    SciTech Connect

    McCready, M.J.

    1990-01-01

    We have examined the mechanism of formation of solitary waves on gas-liquid flows and found, that these form from existing periodic waves which have sufficiently large ({approximately}1.5 to 2 depending upon fluid properties) amplitude to liquid layer-thickness ratios. The exact process for the wave shape change is not understood but it does not seem to be related to the wave steepness (amplitude/wavelength) or to separation of gas flow over the waves. The observed confinement of solitary waves to low liquid Reynolds numbers results because the necessary large precursor waves do not form if the wave speed dispersion is too large or if the wavelength of the dominant waves is too short, as occurs for higher Re{sub L}. Measurements of interface tracings and calculations of power spectra and bispectra as a function of flow distance for conditions close to neutral stability reveal that the initially, linearly unstable mode is stabilized by formation of overtones which are linearly stable and can dissipate energy. As a result, a stable wave field can occur. Mode equations, which include quadratic nonlinearities, can model this process to the extent of producing some degree of quantitative predictions for the amplitudes of the wave modes. However, a complete picture of the wave field must include sidebands as well because these are observed for some flow conditions. 34 refs., 12 figs., 2 tabs.

  15. Modeling Nonequilibrium Gas Flow Based on Moment Equations

    NASA Astrophysics Data System (ADS)

    Torrilhon, Manuel

    2016-01-01

    This article discusses the development of continuum models to describe processes in gases in which the particle collisions cannot maintain thermal equilibrium. Such a situation typically is present in rarefied or diluted gases, for flows in microscopic settings, or in general whenever the Knudsen number—the ratio between the mean free path of the particles and a macroscopic length scale—becomes significant. The continuum models are based on the stochastic description of the gas by Boltzmann's equation in kinetic gas theory. With moment approximations, extended fluid dynamic equations can be derived, such as the regularized 13-moment equations. Moment equations are introduced in detail, and typical results are reviewed for channel flow, cavity flow, and flow past a sphere in the low-Mach number setting for which both evolution equations and boundary conditions are well established. Conversely, nonlinear, high-speed processes require special closures that are still under development. Current approaches are examined, along with the challenge of computing shock wave profiles based on continuum equations.

  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, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 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, 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...

  19. 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... 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. 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...

  1. 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...

  2. 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)

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Breakdown parameter for kinetic modeling of multiscale gas flows.

    PubMed

    Meng, Jianping; Dongari, Nishanth; Reese, Jason M; Zhang, Yonghao

    2014-06-01

    Multiscale methods built purely on the kinetic theory of gases provide information about the molecular velocity distribution function. It is therefore both important and feasible to establish new breakdown parameters for assessing the appropriateness of a fluid description at the continuum level by utilizing kinetic information rather than macroscopic flow quantities alone. We propose a new kinetic criterion to indirectly assess the errors introduced by a continuum-level description of the gas flow. The analysis, which includes numerical demonstrations, focuses on the validity of the Navier-Stokes-Fourier equations and corresponding kinetic models and reveals that the new criterion can consistently indicate the validity of continuum-level modeling in both low-speed and high-speed flows at different Knudsen numbers.

  8. Bypass Flow Resistance in Prismatic Gas-Cooled Nuclear Reactors

    SciTech Connect

    McEligot, Donald M.; Johnson, Richard W.

    2016-12-20

    Available computational fluid dynamics (CFD) predictions of pressure distributions in the vertical bypass flow between blocks in a prismatic gas-cooled reactor (GCR) have been analyzed to deduce apparent friction factors and loss coefficients for systems and network codes. We performed calculations for vertical gap spacings "s" of 2, 6 and 10 mm, horizontal gaps between the blocks of two mm and two flow rates, giving a range of gap Reynolds numbers ReDh of about 40 to 5300. Laminar predictions of the fully-developed friction factor ffd were about three to ten per cent lower than the classical infinitely-wide channel In the entry region, the local apparent friction factor was slightly higher than the classic idealized case but the hydraulic entry length Lhy was approximately the same. The per cent reduction in flow resistance was greater than the per cent increase in flow area at the vertical corners of the blocks. The standard k-ϵ model was employed for flows expected to be turbulent. Its predictions of ffd and flow resistance were significantly higher than direct numerical simulations for the classic case; the value of Lhy was about thirty gap spacings. Initial quantitative information for entry coefficients and loss coefficients for the expansion-contraction junctions between blocks is also presented. Our study demonstrates how CFD predictions can be employed to provide integral quantities needed in systems and network codes.

  9. Bypass Flow Resistance in Prismatic Gas-Cooled Nuclear Reactors

    DOE PAGES

    McEligot, Donald M.; Johnson, Richard W.

    2016-12-20

    Available computational fluid dynamics (CFD) predictions of pressure distributions in the vertical bypass flow between blocks in a prismatic gas-cooled reactor (GCR) have been analyzed to deduce apparent friction factors and loss coefficients for systems and network codes. We performed calculations for vertical gap spacings "s" of 2, 6 and 10 mm, horizontal gaps between the blocks of two mm and two flow rates, giving a range of gap Reynolds numbers ReDh of about 40 to 5300. Laminar predictions of the fully-developed friction factor ffd were about three to ten per cent lower than the classical infinitely-wide channel In themore » entry region, the local apparent friction factor was slightly higher than the classic idealized case but the hydraulic entry length Lhy was approximately the same. The per cent reduction in flow resistance was greater than the per cent increase in flow area at the vertical corners of the blocks. The standard k-ϵ model was employed for flows expected to be turbulent. Its predictions of ffd and flow resistance were significantly higher than direct numerical simulations for the classic case; the value of Lhy was about thirty gap spacings. Initial quantitative information for entry coefficients and loss coefficients for the expansion-contraction junctions between blocks is also presented. Our study demonstrates how CFD predictions can be employed to provide integral quantities needed in systems and network codes.« less

  10. Application Of Phase Doppler Particle Anemometer For Studying Turbulent Gas-Particle Flows At Tsinghua University

    NASA Astrophysics Data System (ADS)

    Zhou, Lixing

    2007-06-01

    The phase Doppler particle anemometer (PDPA) made by both Aerometrcis Inc. and Dantec Inc. are used to measure the time-averaged gas and particle velocities, RMS values of gas and particle fluctuation velocities, gas-particle velocity correlations, gas turbulence modification and particle concentration for turbulent swirling and non-swirling gas-particle flows and also gas-particle flows with combustion in the Laboratory of Two-phase Flows and Combustion, Department of Engineering Mechanics, Tsinghua University. For strongly swirling gas-particle flows with swirl numbers greater than unity (s=1.5 and s=2.1), it is found that their gas-particle flow behavior is different among each other and is different from that for weakly swirling flows. For example, there are no central reverse flows and there are enlarged solid-body rotation zones for swirling flows with s=1.5. The behavior of swirling gas-particle flows depends on the swirl number and the flow configuration. For sudden-expansion gas-particle flows it is found that the gas-particle velocity correlation has the distribution similar to that of gas and particle RMS fluctuation velocities and its magnitude is smaller than that of both gas and particle RMS fluctuation velocities. For turbulence modification in sudden-expansion flows it is found that the separating flows increase the gas-turbulence enhancement tendency in comparison with the pipe flows. For combusting gas-particle flows it is found that combustion reduces the velocity slip between the gas and particle phases.

  11. 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

  12. Optical properties of palladium nanoparticles under exposure of hydrogen and inert gas prepared by dewetting synthesis of thin-sputtered layers

    NASA Astrophysics Data System (ADS)

    Kracker, Michael; Worsch, Christian; Rüssel, Christian

    2013-04-01

    Thin layers of palladium with a thickness of 5 nm were sputtered on fused silica substrates. Subsequently, the coated glasses were annealed at a temperature of 900 °C for 1 h. This resulted in the formation of small and well-separated palladium nanoparticles with diameters in the range from 20 to 200 nm on the glass surface. The existence of a palladium oxide layer can be detected using optical absorption spectroscopy. Purging with hydrogen leads to an irreversible change in the optical spectra due to the reduction of PdO to metallic palladium. Changing the gas atmosphere from hydrogen to argon leads to significant reversible changes in the optical properties of the particle layer. Based on Mie theory and the respective dielectric functions, the spectra were calculated using the real particle size distribution, weighted dispersions relation to adapt the geometrical conditions and complex dielectric functions of palladium and palladium hydride. A good agreement with measured spectra was found and the dependency of the surrounding media can be explained.

  13. Embedding-Free Method for Preparation of Cross-Sections of Organic Materials for Micro Chemical Analysis Using Gas Cluster Ion Beam Sputtering.

    PubMed

    Mihara, Ichiro; Havelund, Rasmus; Gilmore, Ian S

    2017-05-02

    We present a novel in situ mask method for the preparation of cross-sections of organic materials such as polymer multilayer films suitable for chemical imaging of buried interfaces. We demonstrate this method on a model buried interface system consisting of a piece of Scotch tape adhered to a PET substrate and a protective film used in consumer packaging. A high dose of gallium from a focused ion beam (FIB) was used to produce a damaged overlayer on the surface of the organic sample. The damaged layer has a significantly slower sputter rate compared to the native undamaged organic material. Therefore, during gas cluster ion beam (GCIB) depth profiling experiments the damaged layer functions as a mask, protecting the sample beneath and producing a cross-section at the edge of the mask. The FIB itself cannot be used directly to prepare the cross-section since the organic materials are easily damaged. A four step workflow is described including a final cleaning procedure to remove redeposited material from the cross-section. The workflow is completed in a few hours for samples up to 100 μm thickness. The method does not require sample embedding and is suited to automated analysis, which can be important benefits for industrial analysis where a variety of samples are analyzed routinely.

  14. 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

  15. 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.

  16. 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.

  17. Active media inhomogeneities of gas flow lasers. I - Dust content of solid propellant combustion-driven GDL media. II - Gas flow optics of high power gas lasers

    NASA Astrophysics Data System (ADS)

    Borejsho, Anatolij S.; Leonov, Aleksandr F.; Militsyn, Yurij A.; Moshkov, Vladislav L.; Mal'Kov, Viktor M.

    1993-07-01

    This paper discusses some results obtained during our participation in various special-purpose projects for largescale gas lasers. One of most common problems for these systems is the presence of optical inhomogeneities (including solid particles) in the active media caused by both the processes of the media production and the features of gas flow through nozzle banks and cavities. Various optical methods were used to study the inhomogeneities in continuous wave gas dynamic, chemical, and pulsed photodissociating lasers. Solid propellant sources of working media for the gas dynamic lasers are also considered. Dust content of the laser media is discussed with a special consideration as one of the important problems for this type of gas laser.

  18. Extraction and evaluation of gas-flow-dependent features from dynamic measurements of gas sensors array

    NASA Astrophysics Data System (ADS)

    Kalinowski, Paweł; Woźniak, Łukasz; Jasiński, Grzegorz; Jasiński, Piotr

    2016-11-01

    Gas analyzers based on gas sensors are the devices which enable recognition of various kinds of volatile compounds. They have continuously been developed and investigated for over three decades, however there are still limitations which slow down the implementation of those devices in many applications. For example, the main drawbacks are the lack of selectivity, sensitivity and long term stability of those devices caused by the drift of utilized sensors. This implies the necessity of investigations not only in the field of development of gas sensors construction, but also the development of measurement procedures or methods of analysis of sensor responses which compensate the limitations of sensors devices. One of the fields of investigations covers the dynamic measurements of sensors or sensor-arrays response with the utilization of flow modulation techniques. Different gas delivery patterns enable the possibility of extraction of unique features which improves the stability and selectivity of gas detecting systems. In this article three utilized flow modulation techniques are presented, together with the proposition of the evaluation method of their usefulness and robustness in environmental pollutants detecting systems. The results of dynamic measurements of an commercially available TGS sensor array in the presence of nitrogen dioxide and ammonia are shown.

  19. Local pulmonary blood flow: control and gas exchange.

    PubMed

    Sheehan, D W; Farhi, L E

    1993-10-01

    We studied the local response of the pulmonary vasculature to combined changes in alveolar PO2 and PCO2 in the right apical lobe (RAL) of six conscious sheep. That lobe inspired an O2-CO2-N2 mixture adjusted to produce one of 12 alveolar gas compositions: end-tidal PCO2 (PETCO2) of 40, 50, and 60 Torr, each coupled with end-tidal PO2 (PETO2) of 100, 75, 50, and 25 Torr. In addition, at each of the four PETO2, the inspired CO2 was set to 0 and PETCO2 was allowed to vary as RAL perfusion changed. The remainder of the lung, which served as control (CL) inspired air. Fraction of the total pulmonary blood flow going to the RAL (%QRAL) was obtained by comparing the methane elimination from the RAL to that of the whole lung, and expressed as a percentage of that fraction at PETCO2 = 40, PETO2 = 100. Cardiac output, pulmonary vascular pressures, and CL gas tensions were unaffected or only minimally affected by changes in RAL gas composition. A drop in PO2 from 100 to 50 Torr decreased local blood flow by 60% in normocapnia and by 66% at a PCO2 of 60. At all levels of oxygenation, an increase in PCO2 from 40 to 60 reduced QRAL by nearly 50%. With these stimulus-response data, we developed a model of gas exchange, which takes into account the effects of test segment size on blood flow diversion. This model predicts that: (1) when the ventilation to one compartment of a two compartment lung is progressively decreased, PAO2 remains above 60 Torr for up to 60% reductions in alveolar ventilation, irrespective of compartment size; (2) the decrease in PAO2 that occurs at altitude is accompanied by a drop in PACO2 that limits the decrease in conductance and minimizes the pulmonary hypertension; and (3) as we stand, local blood flow control by the alveolar gas tensions halves the alveolar-arterial PO2 and PCO2 differences imposed by gravity.

  20. 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...

  1. 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...

  2. The wide-range ejector flowmeter: calibrated gas evacuation comprising both high and low gas flows.

    PubMed

    Waaben, J; Brinkløv, M M; Jørgensen, S

    1984-11-01

    The wide-range ejector flowmeter is an active scavenging system applying calibrated gas removal directly to the anaesthetic circuit. The evacuation rate can be adjusted on the flowmeter under visual control using the calibration scale ranging from 200 ml X min-1 to 151 X min-1. The accuracy of the calibration was tested on three ejector flowmeters at 12 different presettings. The percentage deviation from presetting varied from + 18 to - 19.4 per cent. The ejector flowmeter enables the provision of consistent and accurately calibrated extraction of waste gases and is applicable within a wide range of fresh gas flows.

  3. 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.

  4. 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.

  5. Molecular dynamics simulations of high speed rarefied gas flows

    NASA Astrophysics Data System (ADS)

    Dongari, Nishanth; Zhang, Yonghao; Reese, Jason M.

    2012-11-01

    To understand the molecular behaviour of gases in high speed rarefied conditions, we perform molecular dynamics (MD) numerical experiments using the open source code Open FOAM. We use shear-driven Couette flows as test cases, where the two parallel plates are moving with a speed of Uw in opposite directions with their temperatures set to Tw. The gas rarefaction conditions vary from slip to transition, and compressibility conditions vary from low speed isothermal to hypersonic flow regimes, i.e. Knudsen number (Kn) from 0.01 to 1 and Mach number (Ma) from 0.05 to 10. We measure the molecular velocity distribution functions, the spatial variation of gas mean free path profiles and other macroscopic properties. Our MD results convey that flow properties in the near-wall non-equilibrium region do not merely depend on Kn, but they are also significantly affected by Ma. These results may yield new insight into diffusive transport in rarefied gases at high speeds.

  6. Effect of various nitrogen flow ratios on the optical properties of (Hf:N)-DLC films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Qi, Meng; Xiao, Jianrong; Cheng, Yong; Wang, Zhiyong; Jiang, Aihua; Guo, Yafang; Tao, Zengren

    2017-08-01

    Hf and N co-doped diamond-like carbon [(Hf:N)-DLC] films were deposited on 316L stainless steel and glass substrates through reactive magnetron sputtering of hafnium and carbon targets at various nitrogen flow ratios (R=N2/[N2+CH4+Ar]). The effects of chemical composition and crystal structure on the optical properties of the (Hf:N)-DLC films were studied. The obtained films consist of uniform HfN nanocrystallines embedded into the DLC matrix. The size of the graphite clusters with sp2 bonds (La) and the ID/IG ratio increase to 2.47 nm and 3.37, respectively, with increasing R. The optical band gap of the films decreases from 2.01 eV to 1.84 eV with increasing R. This finding is consistent with the trends of structural transformations and could be related to the increase in the density of π-bonds due to nitrogen incorporation. This paper reports the influence of nitrogen flow ratio on the correlation among the chemical composition, crystal structure, and optical properties of (Hf:N)-DLC films.

  7. 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

  8. Study of rarefaction effects in gas flows with particle approaches

    NASA Astrophysics Data System (ADS)

    Ngalande, Cedrick Goliati

    The objective of this study is the numerical analysis of gas flow rarefaction phenomena with application to a number of aerospace-related problems. The understanding and accurate numerical prediction of rarefied flow regime is important both for aerospace systems that operate in this regime, and for the development of new generation of gasdriven nano- and micro-scale devices, for which the gas mean free path is comparable with the reference flow scale and rarefaction effects are essential. The main tool for the present analysis is the direct simulations Monte Carlo (DSMC) method. The first topic is the study of rarefied flows in the CHAFF-IV facility. A test particle method was used to analyse the pumping efficiency of CHAFF-IV, and determine optimum geometrical configuration of the chamber. The second topic under consideration is the influence of the surface roughness on nozzle plume flow and plume impingement for different flow regimes from free molecular to near-continuum. Surface roughness effects in rocket nozzles are found to be significant only in very rarefied flows where Reynolds number is about unity. The third topic is the effect of rarefaction on radiometric forces. This effect is shown to be an important factor affecting the radiometric forces. The maximum radiometric forces for all gases under consideration are observed at a Knudsen number of about 0.1. For a radiometer vane placed in a finite size chamber, the maximum force was found to be roughly proportional to the surface area of the vane. This is an indication that the collision-less area force, and not thermal transpiration edge force, dominates the radiometric phenomena in that regime. The role of molecular diameter, viscosity and chamber size on radiometric forces have been found to be significant. The forth topic is the numerical study of the interaction between optical lattices created by two counter-propagating laser beams and initially stagnant gases, in the entire flow regime from free

  9. 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.

  10. Digital image processing based mass flow rate measurement of gas/solid two-phase flow

    NASA Astrophysics Data System (ADS)

    Song, Ding; Peng, Lihui; Lu, Geng; Yang, Shiyuan; Yan, Yong

    2009-02-01

    With the rapid growth of the process industry, pneumatic conveying as a tool for the transportation of a wide variety of pulverized and granular materials has become widespread. In order to improve plant control and operational efficiency, it is essential to know the parameters of the particle flow. This paper presents a digital imaging based method which is capable of measuring multiple flow parameters, including volumetric concentration, velocity and mass flow rate of particles in the gas/solid two phase flow. The measurement system consists of a solid state laser for illumination, a low-cost CCD camera for particle image acquisition and a microcomputer with bespoke software for particle image processing. The measurements of particle velocity and volumetric concentration share the same sensing hardware but use different exposure time and different image processing methods. By controlling the exposure time of the camera a clear image and a motion blurred image are obtained respectively. The clear image is thresholded by OTSU method to identify the particles from the dark background so that the volumetric concentration is determined by calculating the ratio between the particle area and the total area. Particle velocity is derived from the motion blur length, which is estimated from the motion blurred images by using the travelling wave equation method. The mass flow rate of particles is calculated by combining the particle velocity and volumetric concentration. Simulation and experiment results indicate that the proposed method is promising for the measurement of multiple parameters of gas/solid two-phase flow.

  11. Gas flow within Martian soil: experiments on granular Knudsen compressors

    NASA Astrophysics Data System (ADS)

    Koester, Marc; Kelling, Thorben; Teiser, Jens; Wurm, Gerhard

    2017-09-01

    Thermal creep efficiently transports gas through Martian soil. To quantify the Martian soil pump we carried out laboratory analog experiments with illuminated granular media at low ambient pressure. We used samples of 1 μm to 5 μm SiO2 (quartz), basalt with a broad size distribution between 63 μm and 125 μm, and JSC-Mars 1A with a size fraction from 125 μm to 250 μm. The mean ambient pressure was varied between 50 Pa and 9000 Pa. Illumination was varied between 100 W/m2 and 6700 W/m2. The experiments confirm strong directed gas flows within granular and dusty soil and local sub-soil pressure variations. We find that Martian soil pumps can be described with existing models of thermal creep for capillaries, using the average grain size and light flux related temperatures.

  12. 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.

  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. 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.

  15. 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.

  16. Real gas flow fields about three dimensional configurations

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A.; Lombard, C. K.; Davy, W. C.

    1983-01-01

    Real gas, inviscid supersonic flow fields over a three-dimensional configuration are determined using a factored implicit algorithm. Air in chemical equilibrium is considered and its local thermodynamic properties are computed by an equilibrium composition method. Numerical solutions are presented for both real and ideal gases at three different Mach numbers and at two different altitudes. Selected results are illustrated by contour plots and are also tabulated for future reference. Results obtained compare well with existing tabulated numerical solutions and hence validate the solution technique.

  17. Injected power and entropy flow in a heated granular gas

    NASA Astrophysics Data System (ADS)

    Visco, P.; Puglisi, A.; Barrat, A.; Trizac, E.; van Wijland, F.

    2005-10-01

    Our interest goes to the power injected in a heated granular gas and to the possibility to interpret it in terms of entropy flow. We numerically determine the distribution of the injected power by means of Monte Carlo simulations. Then, we provide a kinetic-theory approach to the computation of such a distribution function. Finally, after showing why the injected power does not satisfy a fluctuation relation à la Gallavotti-Cohen, we put forward a new quantity which does fulfill such a relation, and is not only applicable in a variety of frameworks outside the granular world, but also experimentally accessible.

  18. Real gas flow fields about three dimensional configurations

    NASA Technical Reports Server (NTRS)

    Balakrishnan, A.; Lombard, C. K.; Davy, W. C.

    1983-01-01

    Real gas, inviscid supersonic flow fields over a three-dimensional configuration are determined using a factored implicit algorithm. Air in chemical equilibrium is considered and its local thermodynamic properties are computed by an equilibrium composition method. Numerical solutions are presented for both real and ideal gases at three different Mach numbers and at two different altitudes. Selected results are illustrated by contour plots and are also tabulated for future reference. Results obtained compare well with existing tabulated numerical solutions and hence validate the solution technique.

  19. 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.

  20. Ray tracing in nuclear-pumped flowing gas lasers

    SciTech Connect

    Mat'ev, V Yu

    2003-06-30

    The ray tracing in the resonators of a nuclear-pumped flowing gas lasers is considered. The refractive index profile of the medium in a direction perpendicular to the optical axis in such lasers can be considered parabolic, but the steepness of the parabola is quite nonuniform along the ray trace, and the resonator stability condition (the absolute value of the ray matrix trace for a single trip of the ray in the resonator is smaller than two) is not sufficient to confine the ray within the resonator after a large number of trips. (lasers)

  1. 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 22oC 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.

  2. Prediction of inverted velocity profile for gas flow in nanochannel

    NASA Astrophysics Data System (ADS)

    Zhang, T. T.; Ren, Y. R.

    2014-11-01

    Velocity inversion is an interesting phenomenon of nanoscale which means that the velocity near the wall is greater than that of center. To solve this problem, fluid flow in nanochannel attracts more attention in recent years. The physical model of gas flow in two-dimensional nanochannel was established here. To describe the process with conventional control equations, Navier-Stokes equations combined with high-order accurate slip boundary conditions was used as mathematical model. With the introduction of new dimensionless variables, the problem was reduced to an ordinary differential equation. Then it was analytically solved and investigated using homotopy analysis method (HAM). The results were verified by comparing with other available experiment data. Result shows that the proposed method could predict velocity phenomenon.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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).

  8. 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

  9. 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.

  10. Calculation of two-phase flow in gas turbine combustors

    SciTech Connect

    Tolpadi, A.K.

    1995-10-01

    A method is presented for computing steady two-phase turbulent combusting flow in a gas turbine combustor. The gas phase equations are solved in an Eulerian frame of reference. The two-phase calculations are performed by using a liquid droplet spray combustion a model and treating the motion of the evaporating fuel droplets in a Lagrangian frame of reference. The numerical algorithm employs nonorthogonal curvilinear coordinates, a multigrid iterative solution procedure, the standard k-{epsilon} turbulence model, and a combustion model comprising an assumed shape probability density function and the conserved scalar formulation. The trajectory computation of the fuel provides the source terms for all the gas phase equations. This two-phase model was applied to a real piece of combustion hardware in the form of a modern GE/SNECMA single annular CFM56 turbofan engine combustor. For the purposes of comparison, calculations were also performed by treating the fuel as a single gaseous phase. The effect on the solution of two extreme situations of the fuel as a gas and initially as a liquid was examined. The distribution of the velocity field and the conserved scalar within the combustor, as well as the distribution of the temperature field in the reaction zone and in the exhaust, were all predicted with the combustor operating both at high-power and low-power (ground idle) conditions. The calculated exit gas temperature was compared with test rig measurements. Under both low and high-power conditions, the temperature appeared to show an improved agreement with the measured data when the calculations were performed with the spray model as compared to a single-phase calculation.

  11. 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.

  12. Numerical study of liquid-gas flow on complex boundaries

    NASA Astrophysics Data System (ADS)

    Wang, Sheng; Desjardins, Olivier

    2015-11-01

    Simulation techniques for liquid-gas flows near solid boundaries tend to fall two categories, either focusing on accurate treatment of the phase interface away from wall, or focusing on detailed modeling of contact line dynamics. In order to fill the gap between these two categories and to simulate liquid-gas flows in large scale engineering devices with complex boundaries, we develop a conservative, robust, and efficient framework for handling moving contact lines. This approach combines a conservative level set method to capture the interface, an immersed boundary method to represent the curved boundary, and a macroscopic moving contact line model. The performance of the proposed approach is assessed through several simulations. A drop spreading on a flat plate and a circular cylinder validate the equilibrium contact angle. The migration of a drop on an inclined plane is employed to validate the contact line dynamics. The framework is then applied to perform a 3D simulation of the migration of a drop through porous media, which consists of irregular placed cylinders. The conservation error is shown to remain small for all the simulations.

  13. Study of Solid Particle Behavior in High Temperature Gas Flows

    NASA Astrophysics Data System (ADS)

    Majid, A.; Bauder, U.; Stindl, T.; Fertig, M.; Herdrich, G.; Röser, H.-P.

    2009-01-01

    The Euler-Lagrangian approach is used for the simulation of solid particles in hypersonic entry flows. For flow field simulation, the program SINA (Sequential Iterative Non-equilibrium Algorithm) developed at the Institut für Raumfahrtsysteme is used. The model for the effect of the carrier gas on a particle includes drag force and particle heating only. Other parameters like lift Magnus force or damping torque are not taken into account so far. The reverse effect of the particle phase on the gaseous phase is currently neglected. Parametric analysis is done regarding the impact of variation in the physical input conditions like position, velocity, size and material of the particle. Convective heat fluxes onto the surface of the particle and its radiative cooling are discussed. The variation of particle temperature under different conditions is presented. The influence of various input conditions on the trajectory is explained. A semi empirical model for the particle wall interaction is also discussed and the influence of the wall on the particle trajectory with different particle conditions is presented. The heat fluxes onto the wall due to impingement of particles are also computed and compared with the heat fluxes from the gas.

  14. 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)

  15. 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.

  16. Arc-heated gas flow experiments for hypersonic propulsion applications

    NASA Astrophysics Data System (ADS)

    Roseberry, Christopher Matthew

    Although hydrogen is an attractive fuel for a hypersonic air-breathing vehicle in terms of reaction rate, flame temperature, and energy content per unit mass, the substantial tank volume required to store hydrogen imposes a drag penalty to performance that tends to offset these advantages. An alternative approach is to carry a hydrocarbon fuel and convert it on-board into a hydrogen-rich gas mixture to be injected into the engine combustors. To investigate this approach, the UTA Arc-Heated Wind Tunnel facility was modified to run on methane rather than the normally used nitrogen. Previously, this facility was extensively developed for the purpose of eventually performing experiments simulating scramjet engine flow along a single expansion ramp nozzle (SERN) in addition to more generalized applications. This formidable development process, which involved modifications to every existing subsystem along with the incorporation of new subsystems, is described in detail. Fortunately, only a minor plumbing reconfiguration was required to prepare the facility for the fuel reformation research. After a failure of the arc heater power supply, a 5.6 kW plasma-cutting torch was modified in order to continue the arc pyrolysis experiments. The outlet gas flow from the plasma torch was sampled and subsequently analyzed using gas chromatography. The experimental apparatus converted the methane feedstock almost completely into carbon, hydrogen and acetylene. A high yield of hydrogen, consisting of a product mole fraction of roughly 0.7, was consistently obtained. Unfortunately, the energy consumption of the apparatus was too excessive to be feasible for a flight vehicle. However, other researchers have pyrolyzed hydrocarbons using electric arcs with much less power input per unit mass.

  17. 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.

  18. Development of a low flow meter for measuring gas production in bioreactors

    USDA-ARS?s Scientific Manuscript database

    Accurate measurement of gas production from biological processes is important in many laboratory experiments. A gas flow rate measurement system, consisting of an embedded controller operating three gas meters, was developed to measure volumetric flows between 0 and 8 ml min-1 (1 atm, 273.15 K). The...

  19. 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...

  20. 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...

  1. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be... compressed-breathing-gas containers are tested, the flow test shall also be made with 3,450 kN/m.2 (500...

  2. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be... compressed-breathing-gas containers are tested, the flow test shall also be made with 3,450 kN/m.2 (500...

  3. 42 CFR 84.93 - Gas flow test; open-circuit apparatus.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-Contained Breathing Apparatus § 84.93 Gas flow test; open-circuit apparatus. (a) A static-flow test will be... compressed-breathing-gas containers are tested, the flow test shall also be made with 3,450 kN/m.2 (500...

  4. Gas-kinetic BGK Schemes for 3D Viscous Flow

    NASA Astrophysics Data System (ADS)

    Jiang, Jin; Qian, Yuehong

    2009-11-01

    Gas-kinetic BGK scheme developed as an Euler and Navier-Stokes solver is dated back to the early 1990s. There are now numerous literatures on the method. Here we focused on extending this approach to 3D viscous flow. Firstly, to validate the code, some test cases are carried out, including 1D Sod problem, interaction between shock and boundary layer. Then to improve its computational efficiency, two main convergence acceleration techniques, which are local time-stepping and implicit residual smoothing, have adopted and tested. The results indicate that the speed-up to convergence steady state is significant. The last is to incorporate turbulence model into current code with the increasing Reynolds number. As a proof of accuracy, the transonic flow over ONERA M6 wing and pressure distributions at various selected span-wise directions have been tested. The results are in good agreement with experimental data, which implies the extension to turbulent flow is very encouraging and of good help for further development.

  5. Derivation of stable Burnett equations for rarefied gas flows

    NASA Astrophysics Data System (ADS)

    Singh, Narendra; Jadhav, Ravi Sudam; Agrawal, Amit

    2017-07-01

    A set of constitutive relations for the stress tensor and heat flux vector for the hydrodynamic description of rarefied gas flows is derived in this work. A phase density function consistent with Onsager's reciprocity principle and H theorem is utilized to capture nonequilibrium thermodynamics effects. The phase density function satisfies the linearized Boltzmann equation and the collision invariance property. Our formulation provides the correct value of the Prandtl number as it involves two different relaxation times for momentum and energy transport by diffusion. Generalized three-dimensional constitutive equations for different kinds of molecules are derived using the phase density function. The derived constitutive equations involve cross single derivatives of field variables such as temperature and velocity, with no higher-order derivative in higher-order terms. This is remarkable feature of the equations as the number of boundary conditions required is the same as needed for conventional Navier-Stokes equations. Linear stability analysis of the equations is performed, which shows that the derived equations are unconditionally stable. A comparison of the derived equations with existing Burnett-type equations is presented and salient features of our equations are outlined. The classic internal flow problem, force-driven compressible plane Poiseuille flow, is chosen to verify the stable Burnett equations and the results for equilibrium variables are presented.

  6. Return of target material ions leads to a reduced hysteresis in reactive high power impulse magnetron sputtering: Experiment

    NASA Astrophysics Data System (ADS)

    Čapek, Jiří; Kadlec, Stanislav

    2017-05-01

    Titanium and aluminum targets have been reactively sputtered in Ar +O2 or Ar +N2 gas mixtures in order to systematically investigate the effect of reduced hysteresis in reactive high power impulse magnetron sputtering (HiPIMS) as compared to other sputtering techniques utilizing low discharge target power density (e.g., direct current or pulsed direct current mid-frequency magnetron sputtering) operated at the same average discharge power. We found that the negative slope of the flow rate of the reactive gas gettered by the sputtered target material as a function of the reactive gas partial pressure is clearly lower in the case of HiPIMS. This results in a lower critical pumping speed, which implies a reduced hysteresis. We argue that the most important effect explaining the observed behavior is covering of the reacted areas of the target by the returning ionized metal, effectively lowering the target coverage at a given partial pressure. This explanation is supported by a calculation using an analytical model of reactive HiPIMS with time and space averaging (developed by us).

  7. 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.

  8. 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

  9. Multitarget sequential sputtering apparatus

    NASA Technical Reports Server (NTRS)

    Shima, R. (Inventor)

    1975-01-01

    The development and characteristics of a sputtering apparatus are discussed. A potential difference is applied between the cathode and anode to produce a plasma for each target which is sputtered by accelerated ions within the plasma. The process of sputtering for various materials is described. Diagrams of the unit are provided.

  10. Gas molecule-molecule interaction and the gas-surface scattering effect on the rarefied gas flow through a slit into a vacuum

    NASA Astrophysics Data System (ADS)

    Sazhin, O.

    2009-05-01

    The effect of the gas molecule-molecule interaction and the gas-surface scattering on the gas flow through a slit into a vacuum are investigated in a wide range of the gas rarefaction using the direct simulation Monte Carlo method. To study the gas molecule-molecule interaction influence, we used the variable hard sphere and variable soft sphere models defined for an inverse-power-law potential and the generalized hard sphere model defined for the 12-6 Lennard-Jones potential. The Maxwell, Cercignani-Lampis, and Epstein models were used to simulate the gas-surface scattering. This study demonstrates that the gas molecule-molecule interaction can have a significant influence on the rarefied gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. The presented numerical results are in agreement with the corresponding experimental ones.

  11. Gas molecule-molecule interaction and the gas-surface scattering effect on the rarefied gas flow through a slit into a vacuum

    SciTech Connect

    Sazhin, O.

    2009-05-15

    The effect of the gas molecule-molecule interaction and the gas-surface scattering on the gas flow through a slit into a vacuum are investigated in a wide range of the gas rarefaction using the direct simulation Monte Carlo method. To study the gas molecule-molecule interaction influence, we used the variable hard sphere and variable soft sphere models defined for an inverse-power-law potential and the generalized hard sphere model defined for the 12-6 Lennard-Jones potential. The Maxwell, Cercignani-Lampis, and Epstein models were used to simulate the gas-surface scattering. This study demonstrates that the gas molecule-molecule interaction can have a significant influence on the rarefied gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. The presented numerical results are in agreement with the corresponding experimental ones.

  12. 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).

  13. Gas phase depletion and flow dynamics in horizontal MOCVD reactors

    NASA Astrophysics Data System (ADS)

    Van de Ven, J.; Rutten, G. M. J.; Raaijmakers, M. J.; Giling, L. J.

    1986-08-01

    Growth rates of GaAs in the MOCVD process have been studied as a function of both lateral and axial position in horizontal reactor cells with rectangular cross-sections. A model to describe growth rates in laminar flow systems on the basis of concentration profiles under diffusion controlled conditions has been developed. The derivation of the growth rate equations includes the definition of an entrance length for the concentration profile to developed. In this region, growth rates appear to decrease with the 1/3 power of the axial position. Beyond this region, an exponential decrease is found. For low Rayleigh number conditions, the present experimental results show a very satisfactory agreement with the model without parameter fitting for both rectangular and tapered cells, and with both H 2 and N 2 as carrier gases. Theory also predicts that uniform deposition can be obtained over large areas in the flow direction for tapered cells, which has indeed been achieved experimentally. The influence of top-cooling in the present MOCVD system has been considered in more detail. From the experimental results, conclusions could be drawn concerning the flow characteristics. For low Rayleigh numbers (present study ≲ 700) it follows that growth rate distributions correspond with forced laminar flow characteristics. For relatively high Rayleigh numbers (present work 1700-2800), free convective effects with vortex formation are important. These conclusions are not specific for the present system, but apply to horizontal cold-wall reactors in general. On the basis of the present observations, recommendations for a cell design to obtain large area homogeneous deposition have been formulated. In addition, this work supports the conclusion that the final decomposition of trimethylgallium in the MOCVD process mainly takes place at the hot substrate and susceptor and not in the gas phase.

  14. Continuous gas/liquid–liquid/liquid flow synthesis of 4-fluoropyrazole derivatives by selective direct fluorination

    PubMed Central

    Breen, Jessica R; Yufit, Dmitrii S; Howard, Judith A K; Fray, Jonathan; Patel, Bhairavi

    2011-01-01

    Summary 4-Fluoropyrazole systems may be prepared by a single, sequential telescoped two-step continuous gas/liquid–liquid/liquid flow process from diketone, fluorine gas and hydrazine starting materials. PMID:21915207

  15. The flow gradients in the vicinity of a shock wave for a thermodynamically imperfect gas

    NASA Astrophysics Data System (ADS)

    Uskov, V. N.; Mostovykh, P. S.

    2016-11-01

    Supersonic rotational planar and axisymmetric flows of a non-viscous, non-heat-conductive gas with arbitrary thermodynamic properties in the vicinity of a steady shock wave are studied. The differential equations describing the gas flow upstream and downstream of the discontinuity surface and the dynamic compatibility conditions at this discontinuity are used. The gas flow non-uniformity in the shock vicinity is described by the spatial derivatives of the gasdynamic parameters at a point on the shock surface. The parameters are the gas pressure, density, and velocity vector. The derivatives with respect to the directions of the streamline and normal to it, and of the shock surface and normal to it, are considered. Spatial derivatives of all gasdynamic parameters are expressed through the flow non-isobaric factor along the streamline, the streamline curvature, and the flow vorticity and non-isoenthalpy factors. An algorithm for determining these factors of the gas flow downstream of a shock wave is developed. Example calculations of these factors for imperfect oxygen and thermodynamically perfect gas are presented. The influence coefficients of the upstream flow factors on the downstream flow factors are calculated. The gas flow in the vicinity of the shock is described by the isolines of gasdynamic parameters. Uniform planar and axisymmetric flows at different distances from the axis of symmetry are examined; the isobars, isopycnics, isotachs and isoclines are used to characterize the downstream flow behind a curved shock in an imperfect gas.

  16. Gas flow analysis during thermal vacuum test of a spacecraft.

    NASA Technical Reports Server (NTRS)

    Scialdone, J. J.

    1973-01-01

    The pressures indicated by two tubulated ionization gages, one pointing to a spinning spacecraft undergoing thermal vacuum test and the other the walls of the chamber, have been used in a computer program to calculate important parameters of flow kinetics in the vacuum chamber. These parameters calculated as a function of time are: the self-contamination of the spacecraft (defined as the return of outgassed molecules on its critical surfaces either in orbit or while undergoing vacuum test); the spacecraft outgassing including leaks from sealed compartments; and the gas pumping performance of the vacuum chamber. The test indicated the feasibility of this type of evaluation and the improvements in instrumentations and arrangements needed for future tests.

  17. 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.

  18. Tomographic imaging of nonsymmetric multicomponent tailored supersonic flows from structured gas nozzles.

    PubMed

    Golovin, G; Banerjee, S; Zhang, J; Chen, S; Liu, C; Zhao, B; Mills, J; Brown, K; Petersen, C; Umstadter, D

    2015-04-10

    We report experimental results on the production and characterization of asymmetric and composite supersonic gas flows, created by merging independently controllable flows from multiple nozzles. We demonstrate that the spatial profiles are adjustable over a large range of parameters, including gas density, density gradient, and atomic composition. The profiles were precisely characterized using three-dimensional tomography. The creation and measurement of complex gas flows is relevant to numerous applications, ranging from laser-produced plasmas to rocket thrusters.

  19. Localization of shallow gas deposits and uncontrolled gas flows in young and unconsolidated sediments by geophysical methods

    SciTech Connect

    Csoergei, J.; Kummer, I.; Papa, A.; Sipos, J.; Solyom, I.; Takacs, E.; Timar, Z. ); Keresztes, T. )

    1993-09-01

    The great mass of Neogene sediments in the Hungarian basin, where several hydrocarbon accumulations are known, is affected by Pliocene strike-slip movements, resulting in many [open quotes]flower structures.[close quotes] The gas may migrate from the reservoirs upward to the surface along the faults. Thus, shallow gas deposits can be located in the young, unconsolidated sands. There are also several shallow gas deposits derived from uncontrolled gas flows. In Hungary, the shallow gas reservoirs, which are small but increasingly important, have not yet been explored properly. However, the depleting gas may pollute the water in the soil as well as cause explosions. Our purpose is to develop inexpensive, complete, and highly sophisticated field- and data-processing techniques and an integrated complex of geophysical methods in order to define the limits of shallow gas deposits. To avoid anomalous behavior on seismic sections of the depleting gas, we started from uncontrolled gas flows which require special velocity and amplitude vs. offset analyses. In addition, natural and controlled source electromagnetic/electric surveys with various parameters were applied. An industrial-scale seismic section over an uncontrolled gas flow, special sections over flower structures and geoelectric sections, and a magnetic map are presented. The integrated complex of geophysical methods outlined above is being developed in order to establish the conditions for the exploration of gas reservoirs which have been used close to their locality and which could be recovered inexpensively.

  20. 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.

  1. 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

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

    PubMed

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

    2015-08-27

    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.

  3. 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.

  4. Propagation characteristics of pulverized coal and gas two-phase flow during an outburst.

    PubMed

    Zhou, Aitao; Wang, Kai; Fan, Lingpeng; Tao, Bo

    2017-01-01

    Coal and gas outbursts are dynamic failures that can involve the ejection of thousands tons of pulverized coal, as well as considerable volumes of gas, into a limited working space within a short period. The two-phase flow of gas and pulverized coal that occurs during an outburst can lead to fatalities and destroy underground equipment. This article examines the interaction mechanism between pulverized coal and gas flow. Based on the role of gas expansion energy in the development stage of outbursts, a numerical simulation method is proposed for investigating the propagation characteristics of the two-phase flow. This simulation method was verified by a shock tube experiment involving pulverized coal and gas flow. The experimental and simulated results both demonstrate that the instantaneous ejection of pulverized coal and gas flow can form outburst shock waves. These are attenuated along the propagation direction, and the volume fraction of pulverized coal in the two-phase flow has significant influence on attenuation of the outburst shock wave. As a whole, pulverized coal flow has a negative impact on gas flow, which makes a great loss of large amounts of initial energy, blocking the propagation of gas flow. According to comparison of numerical results for different roadway types, the attenuation effect of T-type roadways is best. In the propagation of shock wave, reflection and diffraction of shock wave interact through the complex roadway types.

  5. Regional gastric mucosal blood flow measurements by hydrogen gas clearance in the anesthetized rat and rabbit.

    PubMed

    Leung, F W; Guth, P H; Scremin, O U; Golanska, E M; Kauffman, G L

    1984-07-01

    Hydrogen gas clearance using 3% hydrogen in air and platinum contact electrodes was employed for measuring antral and corpus mucosal blood flow in anesthetized animals. Significantly greater antral than corpus mucosal blood flow was consistently demonstrated. Corpus but not antral mucosal blood flow showed a significant dose-related increase with intravenous pentagastrin. Vasopressin induced a significant dose-related decrease in both antral and corpus mucosal blood flow. Simultaneous measurement of basal corpus mucosal blood flow by hydrogen gas clearance and of gastric mucosal blood flow by aminopyrine clearance gave similar values, but the changes with intravenous pentagastrin or vasopressin measured by aminopyrine clearance were of a much higher order of magnitude. Hydrogen gas clearance, however, reflected changes in left gastric artery blood flow much more closely than did aminopyrine clearance. Therefore, we conclude that the hydrogen gas clearance technique as described is valid for measuring regional gastric mucosal blood flow. It is safe and has potential application in human studies.

  6. Rarefied gas flow in microtubes at different inlet-outlet pressure ratios

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Garimella, S. V.

    2009-05-01

    A model is developed for rarefied gas flow in long microtubes with different inlet-outlet pressure ratios at low Mach numbers. The model accounts for significant changes in Knudsen number along the length of the tube and is therefore applicable to gas flow in long tubes encountering different flow regimes along the flow length. Predictions from the model show good agreement with experimental measurements of mass flow rate, pressure drop, and inferred streamwise pressure distribution obtained under different flow conditions and offer a better match with experiments than do those from a conventional slip flow model.

  7. 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.

  8. Numerical simulation of rarefied gas flow through a slit

    NASA Technical Reports Server (NTRS)

    Keith, Theo G., Jr.; Jeng, Duen-Ren; De Witt, Kenneth J.; Chung, Chan-Hong

    1990-01-01

    Two different approaches, the finite-difference method coupled with the discrete-ordinate method (FDDO), and the direct-simulation Monte Carlo (DSMC) method, are used in the analysis of the flow of a rarefied gas from one reservoir to another through a two-dimensional slit. The cases considered are for hard vacuum downstream pressure, finite pressure ratios, and isobaric pressure with thermal diffusion, which are not well established in spite of the simplicity of the flow field. In the FDDO analysis, by employing the discrete-ordinate method, the Boltzmann equation simplified by a model collision integral is transformed to a set of partial differential equations which are continuous in physical space but are point functions in molecular velocity space. The set of partial differential equations are solved by means of a finite-difference approximation. In the DSMC analysis, three kinds of collision sampling techniques, the time counter (TC) method, the null collision (NC) method, and the no time counter (NTC) method, are used.

  9. 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.

  10. A Simple Model of Gas Flow in a Porous Powder Compact

    SciTech Connect

    Shugard, Andrew D.; Robinson, David

    2012-07-01

    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. High frequency characteristics of FeCoAlO thin films fabricated with asymmetric target at different Ar gas flow rates

    NASA Astrophysics Data System (ADS)

    Zheng, Fu; Luo, Feilong; Lou, Yuanfu; Wang, Ying; Bai, Jianmin; Wei, Dan; Liu, Xiaoxi; Wei, Fulin

    2012-04-01

    FeCoAlO thin films with good soft magnetic properties were fabricated by using RF magnetron sputtering. In order to obtain good high-frequency performance, the in-plane uniaxial anisotropy was tuned by combining the effects of in situ magnetic field and the gradient of Al-O concentration. The composition gradient was controlled by using an asymmetric target and different Ar gas flow rates changing from 5 sccm to 17.5 sccm. It was found that at the range of Ar gas flow rate from 7.5 sccm to 15 sccm, the films showed an excellent high-frequency performance: the resonance frequency was beyond 3.0 GHz and the real permeability μ' had a high value of ˜200 at low-frequency side. In particular, the film prepared at the Ar gas flow rate of 15 sccm showed a resonance frequency of 4.0 GHz. Large resonance frequency can be attributed to the high in-plane uniaxial anisotropy field which was induced by stress and the external magnetic field. The high values of permeability and resonance frequency enable the FeCoAlO thin films to be one of the important candidates for microwave applications.

  12. Effect of Interphase Forces on Gas-Liquid Multiphase Flow in RH Degasser

    NASA Astrophysics Data System (ADS)

    Zhu, Bohong; Liu, Qingcai; Kong, Ming; Yang, Jian; Li, Donghui; Chattopadhyay, Kinnor

    2017-10-01

    A mathematical model was developed to study the gas-liquid flow behavior in the Ruhrstahl-Heraeus (RH) degasser by using the Euler-Euler approach, and the effects of different combinations of interphase forces on the circulation flow rate as well as the distribution of the gas volume fraction were investigated. The results showed that the model predictions correspond with the measured values. As a key factor in avoiding the gas-adhering wall effect, the virtual mass force has a tremendous impact on the circulation flow rate and distribution of the gas volume fraction. The contribution of the turbulent dispersion force on the circulation flow rate is insignificant, but it shows a significant effect on the distribution of the gas volume fraction. Furthermore, the effect of the wall lubrication force and the lift force on gas-liquid flow is negligible when compared with the virtual mass and turbulent dispersion forces.

  13. Effect of Interphase Forces on Gas-Liquid Multiphase Flow in RH Degasser

    NASA Astrophysics Data System (ADS)

    Zhu, Bohong; Liu, Qingcai; Kong, Ming; Yang, Jian; Li, Donghui; Chattopadhyay, Kinnor

    2017-06-01

    A mathematical model was developed to study the gas-liquid flow behavior in the Ruhrstahl-Heraeus (RH) degasser by using the Euler-Euler approach, and the effects of different combinations of interphase forces on the circulation flow rate as well as the distribution of the gas volume fraction were investigated. The results showed that the model predictions correspond with the measured values. As a key factor in avoiding the gas-adhering wall effect, the virtual mass force has a tremendous impact on the circulation flow rate and distribution of the gas volume fraction. The contribution of the turbulent dispersion force on the circulation flow rate is insignificant, but it shows a significant effect on the distribution of the gas volume fraction. Furthermore, the effect of the wall lubrication force and the lift force on gas-liquid flow is negligible when compared with the virtual mass and turbulent dispersion forces.

  14. Distribution of the Transit Flow in the Rotor of a Gas Centrifuge

    NASA Astrophysics Data System (ADS)

    Aleksandrov, O. E.

    2016-09-01

    The present work is devoted to computation of the distribution of the transit flow in the rotor of a separation gas centrifuge. The existing transit-flow models have been considered, the equation to find the transit flow has been obtained, and the basic properties of the transit flow have been analyzed. The general equation for the transit-flow distribution has been obtained, and the transit-flow distribution for a simplified scheme of feed supply, extraction, and waste has been calculated.

  15. Tracheal gas insufflation and related techniques to introduce gas flow into the trachea.

    PubMed

    Hess, D R; Gillette, M A

    2001-02-01

    Over the past 50 years, a variety of techniques have been developed that have in common the insufflation of gas into the central airway to facilitate carbon dioxide (CO2) clearance. These include continuous insufflation of oxygen, transtracheal jet ventilation, high frequency jet ventilation, transtracheal oxygen administration, intratracheal pulmonary ventilation, and tracheal gas insufflation (TGI). Continuous insufflation of oxygen is a technique used to enhance CO2 removal in the presence of apnea. Transtracheal jet ventilation and high frequency jet ventilation promote bulk gas flow into the lungs. Some techniques, such as transtracheal oxygen administration, provide insufflation of oxygen as an adjunct to spontaneous ventilation. However, other techniques, such as TGI, are used as an adjunct to positive pressure ventilation. Intratracheal pulmonary ventilation provides positive pressure ventilation while bypassing the upper airway. Although some of these techniques are promising adjuncts to mechanical ventilation and may help reduce ventilator-associated lung injury, much remains to be learned about their role in the care of patients with acute lung injury.

  16. 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.

    1980-12-01

    The 6000 T/D SRC-I demonstration plant will employ vertical tublar reactors feeding slurry and gas concurrently upward. This reactor is essentially an empty vessel with only a distributor plate located near the inlet. Because the commercial plant represents a considerable scale-up over either Wilsonville or Ft. Lewis, this program is addressing the need for additional data on the behavior of three phase systems in large vessels. Parameters are being studied 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 study program.

  17. Role of rough surface topography on gas slip flow in microchannels.

    PubMed

    Zhang, Chengbin; Chen, Yongping; Deng, Zilong; Shi, Mingheng

    2012-07-01

    We conduct a lattice Boltzmann simulation of gas slip flow in microchannels incorporating rough surface effects as characterized by fractal geometry with a focus on gas-solid interaction. The gas slip flow in rough microchannels, which is characterized by Poiseuille number and mass flow rate, is evaluated and compared with smooth microchannels. The effects of roughness height, surface fractal dimension, and Knudsen number on slip behavior of gas flow in microchannels are all investigated and discussed. The results indicate that the presence of surface roughness reduces boundary slip for gas flow in microchannels with respect to a smooth surface. The gas flows at the valleys of rough walls are no-slip while velocity slips are observed over the top of rough walls. We find that the gas flow behavior in rough microchannels is insensitive to the surface topography irregularity (unlike the liquid flow in rough microchannels) but is influenced by the statistical height of rough surface and rarefaction effects. In particular, decrease in roughness height or increase in Knudsen number can lead to large wall slip for gas flow in microchannels.

  18. 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.}

  19. Steady state cooling flow models with gas loss for normal elliptical galaxies

    NASA Technical Reports Server (NTRS)

    Sarazin, Craig L.; Ashe, Gregory A.

    1989-01-01

    A grid of cooling flow models for the hot gas in normal elliptical galaxies is calculated, including the loss of gas due to inhomogeneous cooling. The loss process is modeled as a distributed sink for the gas with the rate of loss being proportional to the local cooling rate. The cooling flow models with gas loss have smaller sonic radii, smaller inflow rates in their central regions, lower densities, and higher temperatures than homogeneous models. The reduction in the amount of hot gas flowing into the center of the models brings the models into much better agreement with the observed X-ray surface brightness profiles of elliptical galaxies. However, there is a large dispersion in the observed X-ray luminosities of ellipticals, and this cannot be explained by variations in the efficiency of gas loss. The gas-loss models have X-ray surface brightness profiles which are much less centrally peaked than the no-gas-loss models.

  20. 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.

  1. Gas dilution system using critical flow Venturi nozzles for generating primary trace-moisture standards in multiple gas species

    NASA Astrophysics Data System (ADS)

    Amano, Minami; Abe, Hisashi

    2017-02-01

    Gas dilution systems are commonly used to generate calibration gas mixtures for secondary gas standards. However, if a gas dilution system is used to generate gas mixtures for primary trace-moisture standards in multiple gas species, difficulty arises; flow control with relative stability of better than 0.009% is required although the relative uncertainty of the best gas flow meter to date is around 0.3%. In this study, we developed a novel gas dilution system using critical flow Venturi nozzles to address this problem. The developed dilution system can measure and control the flow rates of gases in the range of approximately 0.05 l min-1 to 7 l min-1 (when converted to those measured at 101 325 Pa and 273.15 K) with relative stability of better than 0.007%. Using the dilution system, we developed a magnetic suspension balance/diffusion-tube humidity generator capable of generating trace moisture in N2 in the range of approximately 10 nmol mol-1 to 5 µmol mol-1 in amount fraction. The accuracy of the generated trace-moisture standard was verified by measurement with cavity ring-down spectroscopy.

  2. 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.

  3. Modeling of flowing gas diode pumped alkali lasers: dependence of the operation on the gas velocity and on the nature of the buffer gas.

    PubMed

    Barmashenko, B D; Rosenwaks, S

    2012-09-01

    A simple, semi-analytical model of flowing gas diode pumped alkali lasers (DPALs) is presented. The model takes into account the rise of temperature in the lasing medium with increasing pump power, resulting in decreasing pump absorption and slope efficiency. The model predicts the dependence of power on the flow velocity in flowing gas DPALs and checks the effect of using a buffer gas with high molar heat capacity and large relaxation rate constant between the 2P3/2 and 2P1/2 fine-structure levels of the alkali atom. It is found that the power strongly increases with flow velocity and that by replacing, e.g., ethane by propane as a buffer gas the power may be further increased by up to 30%. Eight kilowatt is achievable for 20 kW pump at flow velocity of 20  m/s.

  4. A Study on the Adhesion Properties of Reactive Sputtered Molybdenum Thin Films with Nitrogen Gas on Polyimide Substrate as a Cu Barrier Layer.

    PubMed

    Kim, Hong Sik; Kim, Byoung O; Seo, Jong Hyun

    2015-11-01

    NiCr, Mo, and Mo-N thin copper diffusion barrier films are deposited on 200 um thick polyimide films spin-coated on glass substrates by dc reactive magnetron sputtering. The adhesion forces for three systems are measured by micro-scratch test analysis depending on oxygen plasma pretreatment, sputtering power density, moisture contents, and post annealing treatment. The values of adhesion forces for the three systems are linearly proportional to the oxygen plasma treatment time. As deposition power density increases, measured adhesion forces also increase. The existence of moisture adsorbed in the polymer substrate prior to initiating the sputtering process significantly reduces the adhesion force for all systems. Post annealing treatment at 150 degrees C for 12 hours after sputtering also deteriorates the adhesion between the barrier films and polymer substrate. Auger electron spectroscopy reveals that adhesion forces are significantly dependent on the types of compounds formed at the barrier layer/polymer interface. Changes in the adhesion properties of the MoN system as a function of the nitrogen content are explained in terms of the mechanical stability of the MoN(x)O(y) interface layer on the polymer substrate.

  5. 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.

  6. 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.

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

    DOEpatents

    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.

  8. 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

  9. 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.

  10. 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.

  11. Use of schlieren methods to study gas flow in laser technology

    NASA Astrophysics Data System (ADS)

    Mrňa, Libor; Pavelka, Jan; Horník, Petr; Hrabovský, Jozef

    2016-11-01

    Laser technologies such as welding and cutting rely on process gases. We suggest to use schlieren imaging to visualize the gas flow during these processes. During the process of laser welding, the shielding gas flows to the welded area to prevent oxidation of the weld pool by surrounding air. The gas also interacts with hot plasma spurting from the key hole induced by the laser beam incident on the molten material. This interaction is quite complicated because hot plasma mixes with the cold shielding gas while the system is moving along the weld. Three shielding gases were used in the presented experiment: Ar, He and N2. Differences in dynamics of the flow are clearly visible on schlieren images. Moreover, high speed recording reveals a structure consisting of hot gas bubbles. We were also able to determine the velocity of the bubbles from the recording. During laser cutting, the process gas flows coaxially with the laser beam from the nozzle to remove the molten material out of the kerf. The gas flow is critical for the quality of the resulting edge of the cut. Schlieren method was used to study gas flow under the nozzle and then under the material being cut. This actually creates another slot nozzle. Due to the very low speed of flow below the material the schleiren method is already at the limit of its sensitivity. Therefore, it is necessary to apply a differential technique to increase the contrast. Distinctive widening of the flow shaped by the kerf was observed.

  12. 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.

  13. Method for varying the cross-sectional flow area in a radial gas turbine inlet

    SciTech Connect

    Stroem, S.

    1987-06-23

    This patent describes a method for varying the effective flow area of combustion gases in a gas turbine engine comprising the steps of: passing the combustion gases through a confined area; separating the gas flowing through the confined area into at least first and second streams of gas; injecting fluid under pressure into one of the first and second streams for closing off the flow of combustion gases in one of the streams; and channeling the remaining gas stream directly onto a turbine rotor.

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

    SciTech Connect

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

    2016-05-23

    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. Generalized second-order slip boundary condition for nonequilibrium gas flows.

    PubMed

    Guo, Zhaoli; Qin, Jishun; Zheng, Chuguang

    2014-01-01

    It is a challenging task to model nonequilibrium gas flows within a continuum-fluid framework. Recently some extended hydrodynamic models in the Navier-Stokes formulation have been developed for such flows. A key problem in the application of such models is that suitable boundary conditions must be specified. In the present work, a generalized second-order slip boundary condition is developed in which an effective mean-free path considering the wall effect is used. By combining this slip scheme with certain extended Navier-Stokes constitutive relation models, we obtained a method for nonequilibrium gas flows with solid boundaries. The method is applied to several rarefied gas flows involving planar or curved walls, including the Kramers' problem, the planar Poiseuille flow, the cylindrical Couette flow, and the low speed flow over a sphere. The results show that the proposed method is able to give satisfied predictions, indicating the good potential of the method for nonequilibrium flows.

  16. Growth of a Massive Young Stellar Object Fed by a Gas Flow from a Companion Gas Clump

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Ren, Zhiyuan; Zhang, Qizhou; Shen, Zhiqiang; Qiu, Keping

    2017-02-01

    We present a Submillimeter Array (SMA) observation toward the young massive double-core system G350.69-0.49. This system consists of a northeast (NE) diffuse gas bubble and a southwest (SW) massive young stellar object (MYSO), both clearly seen in the Spitzer images. The SMA observations reveal a gas flow between the NE bubble and the SW MYSO in a broad velocity range from 5 to 30 km s-1 with respect to the system velocity. The gas flow is well confined within the interval between the two objects and traces a significant mass transfer from the NE gas bubble to the SW massive core. The transfer flow can supply the material accreted onto the SW MYSO at a rate of 4.2 × 10-4 M⊙ yr-1. The whole system therefore suggests a mode for the mass growth in the MYSO from a gas transfer flow launched from its companion gas clump, despite the driving mechanism of the transfer flow not being fully determined from the current data.

  17. Slug front gas entrainment in gas-liquid two-phase horizontal flow using hi-speed slug-tracking

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Matar, Omar; Markides, Christos

    2013-11-01

    A gas-liquid flow regime where liquid-continuous regions travel at high speeds (i.e. slugs) through a pipe separated by regions of stratified flow (i.e. elongated bubbles) is referred to as a ``slug flow.'' This regime is characterised by the turbulent entrainment of gas into the slug front body. We use a high-speed camera mounted on a moving robotic linear rail to track the formation of naturally occurring slugs over 150 pipe diameters. We show that the dynamics of the slugs become progressively more complex with increasing liquid and gas Reynolds numbers. Based on the slug-tracking visualization we present, over a range of conditions: (i) phenomenological observations of the formation and development of slugs, and (ii) statistical data on the slug velocity and gas entrainment rate into the slug body. EPSRC Programme Grant EP/K003976/1.

  18. Examination of optimal separator shape of polymer electrolyte fuel cell with numerical analysis including the effect of gas flow through gas diffusion layer

    NASA Astrophysics Data System (ADS)

    Inoue, Gen; Matsukuma, Yosuke; Minemoto, Masaki

    This work concentrates on the effects of channel depth and separator shape on cell output performance, current density distribution and gas flow condition in various conditions with PEFC numerical analysis model including gas flow through GDL. When GDL effective porosity was small, the effect of gas flow through GDL which was changed by channel depth on cell output performance became large. However, current density distribution was ununiform. As GDL permeability became larger, cell output density increased, but current density and gas flow rate distribution were ununiform. From the results of changing the gas flow rate, it was found that the ratio of the minimum gas flow rate to the inlet flow rate depended on channel depth. Furthermore, the optimal separator, which increased output density and made the current density distribution and gas flow rate distribution uniform, was examined. It was also found that cell performance had possible to be developed by improving the turning point of the serpentine separator.

  19. 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.

  20. Estimation of gas flow dustiness in the main pipelines of booster compressor stations

    NASA Astrophysics Data System (ADS)

    Yukhymenko, M.; Ostroha, R.; Litvinenko, A.; Bocko, J.

    2017-08-01

    The article provides groundings for cleaning the gas flows of major pipelines from soild particles in order to improve the compressor operation reliability. One obtained formulas for determination of the dust level in the vertical and horizontal sections of the pipelines supplying gas to the booster compressor stations. Ways of structural modernization of vertical pipeline sections using the inbuilt separation devices for more efficient removal of dust particles from the gas flow are described.

  1. Hybrid Particle-Continuum Methods for Nonequilibrium Gas and Plasma Flows

    DTIC Science & Technology

    2010-07-01

    boundary layers, and by rarefied flow conditions. Another form of nonequilibrium concerns different species in the gas or plasma having very different...Methods for Nonequilibrium Gas and Plasma Flows 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Iain D. Boyd (University of Michigan) 5d...Symposium on Rarefied Gas Dynamics, Monterey, CA, 10-15 July 2010. 14. ABSTRACT Two different hybrid particle-continuum methods are described for

  2. 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.

  3. Multi-scale gas flow in Bazhen formation shales

    NASA Astrophysics Data System (ADS)

    Vasilyev, R.; Gerke, K.; Korost, D. V.; Karsanina, M.; Balushkina, N. S.; Kalmikov, G. A.; Mallants, D.

    2013-12-01

    scans (1 μm resolution). High resolution SEM images (with resolution up to 10 nm) are used to reconstruct the 3D structure of kerogen nanoporosity. Pore-networks are extracted directly from 3D images using the maximal ball extraction algorithm, or pore-network parameters were combined (pore and throat size distributions and connection number statistics) to merge macro and nanoscale porosities using a previously developed concept of under-resolution porosity (Korost and Gerke, 2012). Using analytical relationships between conductance and pressure for nanopores (Mehmani et al., 2013), the gas permeability was solved iteratively. For samples with dominant kerogen type nanoporosity we obtained satisfactory predictions of gas permeability. Finally, we also discuss current problems and future challenges (e.g., oil flow). This work was partially supported by RFBR grants 12-05-33089, 12-04-32264, 13-04-00409, 13-05-01176 and 12-05-01130.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. High Bias Gas Flows Increase Lung Injury in the Ventilated Preterm Lamb

    PubMed Central

    Bach, Katinka P.; Kuschel, Carl A.; Hooper, Stuart B.; Bertram, Jean; McKnight, Sue; Peachey, Shirley E.; Zahra, Valerie A.; Flecknoe, Sharon J.; Oliver, Mark H.; Wallace, Megan J.; Bloomfield, Frank H.

    2012-01-01

    Background Mechanical ventilation of preterm babies increases survival but can also cause ventilator-induced lung injury (VILI), leading to the development of bronchopulmonary dysplasia (BPD). It is not known whether shear stress injury from gases flowing into the preterm lung during ventilation contributes to VILI. Methods Preterm lambs of 131 days’ gestation (term = 147 d) were ventilated for 2 hours with a bias gas flow of 8 L/min (n = 13), 18 L/min (n = 12) or 28 L/min (n = 14). Physiological parameters were measured continuously and lung injury was assessed by measuring mRNA expression of early injury response genes and by histological analysis. Control lung tissue was collected from unventilated age-matched fetuses. Data were analysed by ANOVA with a Tukey post-hoc test when appropriate. Results High bias gas flows resulted in higher ventilator pressures, shorter inflation times and decreased ventilator efficiency. The rate of rise of inspiratory gas flow was greatest, and pulmonary mRNA levels of the injury markers, EGR1 and CTGF, were highest in lambs ventilated with bias gas flows of 18 L/min. High bias gas flows resulted in increased cellular proliferation and abnormal deposition of elastin, collagen and myofibroblasts in the lung. Conclusions High ventilator bias gas flows resulted in increased lung injury, with up-regulation of acute early response genes and increased histological lung injury. Bias gas flows may, therefore, contribute to VILI and BPD. PMID:23056572

  12. Flow mechanism of Forchheimer's cubic equation in high-velocity radial gas flow through porous media. [High-velocity, high-pressure gas flow through porous media near the wellbore

    SciTech Connect

    Ezeudembah; Dranchuk, P.M.

    1982-09-01

    Until recently, the visco-inertial flow equation, which is an adaptation of Forchheimer's quadratic equation, has been used to describe gas flow behavior at higher flow rates and pressures. The inability of this equation, in some cases, to fully describe high-velocity, high-pressure gas flow behavior, especially around the well bore, led to the consideration of other empirical equations. In this paper, 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, i.e. Darcy type, inertial type, and turbulent. 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 directly related 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.

  13. 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.

  14. 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.

  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. 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.

  17. Carbothermic Reduction of Chromite Ore Under Different Flow Rates of Inert Gas

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dolly; Ranganathan, S.; Sinha, S. N.

    2010-02-01

    The reduction of chromite ore with carbon has been studied extensively in many laboratories. Inert gases have been used in these investigations to control the experimental conditions. However, little information is available in the literature on the influence of the gas flow rate on the rate of reduction. Experiments were carried out to study the influence of the flow rate of inert gas on the reducibility of chromite ore. The experiments showed that the rate of reduction increased with the increasing flow rate of argon up to an optimum flow rate. At higher flow rates, the rate of reduction decreased. The influence of the proportion of reductant on the extent of reduction depended on the rate of flow rate of inert gas. The experimental results are interpreted on the basis of a model that postulates that the mechanism of reduction changes with the flow rate of argon.

  18. 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.

  19. Methane production rate studies and gas flow modeling for the fresh kills landfill. Interim report

    SciTech Connect

    Kunz, C.O.; Lu, A.H.

    1980-11-01

    Methane is produced in landfills by anaerobic bacteria in the digestion of various organic materials found in the wastes. With the increasing cost of fuels the recovery of methane can be economic from some landfills. The rate of methane production can vary widely depending on factors such as the moisture content of the wastes, the pH, toxicity, temperature and amount of organic material available. Information regarding the rate of gas production and gas flow during pumping is needed to determine the potential of a site for methane recovery and in the design of a recovery system. The primary objective of this study was to develop gas flow models based on measurements of the pressure differential between landfill gas and atmospheric pressure that would enable the rate of gas production to be estimated. In the course of this investigation two landfill gas flow models were developed; a static model and a dynamic model.

  20. Methane-production-rate studies and gas-flow modeling for the Fresh Kills landfill

    SciTech Connect

    Kunz, C.O.; Lu, A.H.

    1980-11-01

    Methane is produced in landfills by anaerobic bacteria in the digestion of various organic materials found in the wastes. With the increasing cost of fuels the recovery of methane can be economic for some landfills. The rate of methane production can vary widely depending on factors such as the moisture content of the wastes, the pH, toxicity, temperature and the amount of organic material available. Information regarding the rate of gas production and gas flow during pumping is needed to determine the potential of a site for methane recovery and in the design of a recovery system. The primary objective of this study was to develop gas flow models based on measurements of the pressure differential between landfill gas and atmospheric pressure that would enable the rate of gas production to be estimated. In the course of this investigation two landfill gas flow models were developed; a static model and a dynamic model.

  1. A novel approach for the characterization of a bilayer of phenyl-c71-butyric-acid-methyl ester and pentacene using ultraviolet photoemission spectroscopy and argon gas cluster ion beam sputtering process

    SciTech Connect

    Yun, Dong-Jin; Chung, JaeGwan; Jung, Changhoon; Chung, Yeonji; Kim, SeongHeon; Lee, Seunghyup; Kim, Ki-Hong; Han, Hyouksoo; Park, Gyeong-Su; Park, SungHoon

    2013-09-07

    The material arrangement and energy level alignment of an organic bilayer comprising of phenyl-c71-butyric-acid-methyl ester (PCBM-71) and pentacene were studied using ultraviolet photoelectron spectroscopy (UPS) and the argon gas cluster ion beam (GCIB) sputtering process. Although there is a small difference in the full width at half maximum of the carbon C 1s core level peaks and differences in the oxygen O 1s core levels of an X-ray photoemission spectroscopy spectra, these differences are insufficient to clearly distinguish between PCBM-71 and pentacene layers and to classify the interface and bulk regions. On the other hand, the valence band structures in the UPS spectra contain completely distinct configurations for the PCBM-71 and pentacene layers, even when they have similar atomic compositions. According to the valence band structures of the PCBM-71/pentacene/electrodes, the highest unoccupied molecular orbital (HOMO) region of pentacene is at least 0.8 eV closer to the Fermi level than that of PCBM-71 and it does not overlap with any of the chemical states in the valence band structure of PCBM-71. Therefore, by just following the variations in the area of the HOMO region of pentacene, the interface/bulk regions of the PCBM/pentacene layers were distinctly categorized. Besides, the variation of valence band structures as a function of the Ar GCIB sputtering time fully corroborated with the surface morphologies observed in the atomic force microscope images. In summary, we believe that the novel approach, which involves UPS analysis in conjunction with Ar GCIB sputtering, can be one of the best methods to characterize the material distribution and energy level alignments of stacks of organic layers.

  2. Numerical study of gas-liquid flow morphology in a vertical flowmeter nozzle

    NASA Astrophysics Data System (ADS)

    Kartushinsky, Alexander; Balakin, Boris V.; Kutsenko, Kirill V.; Kosinski, Pawel

    2017-07-01

    Industrial multiphase flow measurement systems often contain meters based on Venturi principle. Those instruments deal with the differential pressure measurements whose accurate interpretation is possible when the flow morphology is known a-priori. The present paper reports the results of CFD-modelling of a gas-liquid flow through a vertical nozzle accompanied by a blind-T flow conditioner. The model is used for evaluation of the flow morphology in case the volume fractions of both phases are comparable. The model demonstrates high non-uniformities of the flow field after the blind-T, which indicates that this type of flow conditioners may lead to inaccurate results.

  3. Combined simulation of combustion and gas flow in a grate-type incinerator.

    PubMed

    Ryu, C; Shin, D; Choi, S

    2002-02-01

    Computational fluid dynamic (CFD) analysis of the thermal flow in the combustion chamber of a solid waste incinerator provides crucial insight into the incinerator's performance. However, the interrelation of the gas flow with the burning waste has not been adequately treated in many CFD models. A strategy for a combined simulation of the waste combustion and the gas flow in the furnace is introduced here. When coupled with CFD, a model of the waste combustion in the bed provides the inlet conditions for the gas flow field and receives the radiative heat flux onto the bed from the furnace wall and gaseous species. An unsteady one-dimensional bed model was used for the test simulation, in which the moving bed was treated as a packed bed of homogeneous fuel particles. The simulation results show the physical processes of the waste combustion and its interaction with the gas flow for various operational parameters.

  4. Bubble formation during horizontal gas injection into downward-flowing liquid

    NASA Astrophysics Data System (ADS)

    Bai, Hua; Thomas, Brian G.

    2001-12-01

    Bubble formation during gas injection into turbulent downward-flowing water is studied using high-speed videos and mathematical models. The bubble size is determined during the initial stages of injection and is very important to turbulent multiphase flow in molten-metal processes. The effects of liquid velocity, gas-injection flow rate, injection hole diameter, and gas composition on the initial bubble-formation behavior have been investigated. Specifically, the bubble-shape evolution, contact angles, size, size range, and formation mode are measured. The bubble size is found to increase with increasing gas-injection flow rate and decreasing liquid velocity and is relatively independent of the gas injection hole size and gas composition. Bubble formation occurs in one of four different modes, depending on the liquid velocity and gas flow rate. Uniform-sized spherical bubbles form and detach from the gas injection hole in mode I for a low liquid speed and small gas flow rate. Modes III and IV occur for high-velocity liquid flows, where the injected gas elongates down along the wall and breaks up into uneven-sized bubbles. An analytical two-stage model is developed to predict the average bubble size, based on realistic force balances, and shows good agreement with measurements. Preliminary results of numerical simulations of bubble formation using a volume-of-fluid (VOF) model qualitatively match experimental observations, but more work is needed to reach a quantitative match. The analytical model is then used to estimate the size of the argon bubbles expected in liquid steel in tundish nozzles for conditions typical of continuous casting with a slide gate. The average argon bubble sizes generated in liquid steel are predicted to be larger than air bubbles in water for the same flow conditions. However, the differences lessen with increasing liquid velocity.

  5. DSMC-computation of the Rarefied Gas Flow through a Slit into a Vacuum

    NASA Astrophysics Data System (ADS)

    Sazhin, Oleg

    2008-12-01

    The gas rarefaction, gas molecule-molecule interaction and gas-surface scattering influence on the gas flow through a slit into a vacuum is investigated by the direct simulation Monte Carlo (DSMC) method. To study the gas molecule-molecule interaction influence on the gas flow we used the hard sphere (HS), variable hard sphere (VHS) anc variable soft sphere (VSS) models defined for the inverse-power-law (IPL) potential and also the generalized hard sphere (GHS) model defined for the 12-6 Lennard-Jones (LJ) potential. Maxwell (specular-diffuse scheme), Cercignani-Lampis (CL) and Epstein approaches were used to simulate the gas-surface scattering. The results of computations of the mas; flow rate in a wide range of rarefactions and distributions of the density, temperature and mass velocity, and streamlines are presented. This study demonstrates that the gas molecule-molecule interaction significantly interferes with the gas flow through a slit, while the influence of the gas-surface scattering is negligibly small. Our results are in agreement with the corresponding theoretical asymptotes, experimental and numerical data.

  6. 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.

  7. 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.

  8. 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.

  9. The Interaction of Radio Sources and X-Ray-Emitting Gas in Cooling Flows

    NASA Astrophysics Data System (ADS)

    Blanton, E. L.

    Recent observations of the interactions between radio sources and the X-ray-emitting gas in cooling flows in the cores of clusters of galaxies are reviewed. The radio sources inflate bubbles in the X-ray gas, which then rise buoyantly outward in the clusters transporting energy to the intracluster medium (ICM). The bright rims of gas around the radio bubbles are cool, rather than hot, and do not show signs of being strongly shocked. Energy deposited into the ICM over the lifetime of a cluster through several outbursts of a radio source helps to account for at least some of the gas that is missing in cooling flows at low temperatures.

  10. Gas flow in a system of coaxial cylinders during their partial destruction

    NASA Astrophysics Data System (ADS)

    Borisov, A. S.; Dvoretskii, V. M.; Shishkov, A. A.

    The paper presents an investigation of gas flow into a closed volume in the presence of partial and successive destruction of gas-filled cylindrical shells. The region being destroyed is represented as an arbitrarily situated annular slit. The investigation is based on the numerical integration of unsteady gasdynamic equations using the Godunov finite-difference scheme. The effect of gas temperature on pressure variations in the system is analyzed, and data are obtained on gas-flow characteristics as the slit size is varied. The results obtained are of interest in connection with protecting test equipment from destruction during accidents occurring in aircraft and spacecraft flight simulation experiments.

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

    DOEpatents

    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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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).

  17. Gas-liquid pipe flow under microgravity conditions: influence of tube diameter on flow patterns and pressure drops

    NASA Astrophysics Data System (ADS)

    Colin, C.; Fabre, J.

    1995-08-01

    Gas-liquid flow experiments have been performed in small tubes of 19 mm, 10 mm and 6 mm diameter, during parabolic flights, for a range of superficial liquid velocities from 0.1 to 2 m/s and superficial gas velocities from 0.05 m/s to 10 m/s. Results are compared to those previously obtained by Colin et al., /1/, in a 40 mm i.d. tube. The flow patterns identified are: bubbly flow, slug flow and a pattern halfway between slug and annular flows. The main difference between the experiments in small tubes and the previous ones, concerns the transition between bubbly flow and slug flow, the role of coalescence and the wall friction factor. Coalescence is shown to play a major role in the transition from bubbly to slug flow. In particular at small Reynolds number coalescence seems to be partly inhibited. Single-phase flow correlations for wall shear stress underestimate the wall friction factor in the intermediate range of Reynolds number between laminar and turbulent flow.

  18. Investigation of plasma spokes in reactive high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Corbella, C.; Maszl, C.; Breilmann, W.; von Keudell, A.

    2017-05-01

    Spokes, localised ionisation zones, are commonly observed in magnetron sputtering plasmas, appearing either with a triangular shape or with a diffuse shape, exhibiting self-organisation patterns. In this paper, we investigate the spoke properties (shape and emission) in a high power impulse magnetron sputtering (HiPIMS) discharge when reactive gas (N2 or O2) is added to the Ar gas, for three target materials; Al, Cr, and Ti. Peak discharge current and total pressure were kept constant, and the discharge voltage and mass flow ratios of Ar and the reactive gas were adjusted. The variation of the discharge voltage is used as an indication of a change of the secondary electron yield. The optical emission spectroscopy data demonstrate that by addition of reactive gas, the HiPIMS plasma exhibits a transition from a metal dominated plasma to the plasma dominated by Ar ions and, at high reactive gas partial pressures, to the plasma dominated by reactive gas ions. For all investigated materials, the spoke shape changed to the diffuse spoke shape in the poisoned mode. The change from the metal to the reactive gas dominated plasma and increase in the secondary electron production observed as the decrease of the discharge voltage corroborate our model of the spoke, where the diffuse spoke appears when the plasma is dominated by species capable of generating secondary electrons from the target. Behaviour of the discharge voltage and maximum plasma emission is strongly dependant on the target/reactive gas combination and does not fully match the behaviour observed in DC magnetron sputtering.

  19. 40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 19 2011-07-01 2011-07-01 false Gas meter or flow instrumentation... Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1320-90 Gas meter or flow..., methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to...

  20. 40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Gas meter or flow instrumentation... Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1320-90 Gas meter or flow..., methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to...

  1. 40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Gas meter or flow instrumentation... Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1320-90 Gas meter or flow..., methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to...

  2. 40 CFR 86.1320-90 - Gas meter or flow instrumentation calibration; particulate, methanol, and formaldehyde measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Gas meter or flow instrumentation... Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1320-90 Gas meter or flow..., methanol and formaldehyde emissions requires the use of gas meters or flow instrumentation to...

  3. 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.

  4. 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.

  5. Technological study of laser cutting silicon steel controlled by rotating gas flow

    NASA Astrophysics Data System (ADS)

    Lei, Hong; Yi, Zhang; chenglong, Mi

    2009-04-01

    Using traditional laser cutting technology, it is easy to produce molten slag in laser cutting silicon steel sheet. The main reason is the inevitable oxidizing reaction in the process caused by the use of oxygen as the aided gas. As a common solution, high pressure and high purity N 2 or an inert gas is therefore used instead of oxygen. Although the cut quality is improved, the cutting efficiency is reduced because of the lack of energy generated from an exothermic oxidation reaction. The technology used in this paper is to employ a newly developed cyclone slag separator. The slag separator is located under the workpiece to form rotating gas flow for controlling the direction of the flowing slag gas. Adopting the new technology reported here, oxygen is still used as the aided gas. The experiments prove that, by controlling the technical parameters reasonably tightly, glossy and dross-free cutting kerfs are obtained for reduced laser power. The gas flow acting under the workpiece is simulated using the finite element method (FEM). The operating law of the rotating gas flow is verified by ANSYS, which provides an academic basis for controlling the flowing direction of the slag gas.

  6. Refractive index of thin films realized by Satisloh SP reactive sputtering system

    NASA Astrophysics Data System (ADS)

    Monaco, Gianni; Colautti, Arturo; Allegro, Cristina; Godin, Tom; Gold, Steffan; Witzany, Michael

    2013-09-01

    Pulsed DC reactive sputtering is a very interesting technique for coating applications. Reactive sputtering can give very dense layers, low stress of the deposited multilayer film, high reproducibility, very high hardness (up to 1200 Vickers hardness) with unbeatable high rates ideal for industrial applications. SP-100 is Satisloh reactive sputtering systems with only one target material but can deposit various film materials simply by using different gases such as argon, as well as the reactive gases nitrogen and oxygen. Silicon-oxides, silicon-nitrides and all kinds of silicon-oxy-nitrides (SiOx-SixOyNz-SixNy) with a refractive index range of 1.44-2.05 in the visible range can be obtained. In the reactive sputtering the material it is usually deposited in the so called "transition mode" where it must be found the correct equilibrium point between the target voltage and the reactive gas flow. The transition mode assures a dense film with a stable rate. Condition to find such equilibrium point is given by the so called "material hysteresis" in which the target voltage is depicted in function of the reactive gas voltage. The hysteresis and the consequent equilibrium point are strongly depended by the power supplied to the target and the inert gas (argon) flow which could affect the optical characteristics and the deposition rate. We checked the refractive indexes of the SiOx and SixNy of very thin (1 QW Optical thickness at 520 nm) and thicker (3, 5 and 9 QW @520 nm) reporting how the different conditions can affect the refractive index and the deposition rate of the different materials.

  7. Investigation of Gas and Fluid Flow through a Single Nanopore

    NASA Astrophysics Data System (ADS)

    Friedman, Serah; Velasco, Angel; Siwy, Zuzanna; Taborek, Peter

    2011-11-01

    Mass flow through ion-track etched nanopores with diameters ranging in size from 100 to 300 nm was measured using mass spectrometry. The thickness of the membrane was 12 micron, so our system was modeled after flow through a long pipe. The mass flow was caused by a pressure difference across the membrane of order 1 atm, with the low pressure side at vacuum. At room temperature diffusive transport through the membrane was comparable to mass flow through the hole so the temperature was lowered to -50 C which stopped the diffusive transport. The flow rates for gaseous Helium, Argon, and Nitrogen were studied and agreed with theory at a variety of Knudsen numbers. In contrast, with liquid water or Nitrogen on the high pressure side of the membrane, preliminary results show higher flow rates than can be accounted for by classical viscous flow theory.

  8. Performance characteristics of a transverse-flow, oxygen-iodine chemical laser in a low gas-flow velocity

    NASA Astrophysics Data System (ADS)

    Watanabe, K.; Kashiwabara, S.; Sawai, K.; Toshima, S.; Fujimoto, R.

    1983-03-01

    Performance characteristics are reported for a transverse-flow, oxygen-iodine chemical laser which operates at a low level (8 m/s) of linear flow gas velocity using a small size vacuum pump. This is the first time that dependences of laser output power have experimentally been found on Cl2 and I2 flow rates. Output powers in excess of 10 W have been efficiently extracted from a 50 x 0.5-cm rectangular flow duct. A total energy of 11 kJ from one gram of iodine has been obtained. The reaction mechanisms associated with the power decrease in high concentrations of I2 are carefully discussed.

  9. 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.

  10. 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.

  11. Gas phase dispersion in compost as a function of different water contents and air flow rates.

    PubMed

    Sharma, Prabhakar; Poulsen, Tjalfe G

    2009-07-21

    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.

  12. Flow Characteristics of a Multiple Nozzle Exhaust Gas Eductor System.

    DTIC Science & Technology

    1981-03-01

    and the requirement for a relatively large amount of combustion ai-, a large quantity of hot exhaust gas is generated. Due to gas turbine design...Fi- fures 25a through 25g. It was further noted that decreasing the number of tertiary ports open had the effect of increasing the secondary pumping

  13. 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.

  14. 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.

  15. 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.

  16. Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers.

    PubMed

    Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

    2017-07-18

    Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. Graphical Abstract ᅟ.

  17. Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

    2017-10-01

    Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered. [Figure not available: see fulltext.

  18. Gas Flow in the Capillary of the Atmosphere-to-Vacuum Interface of Mass Spectrometers

    NASA Astrophysics Data System (ADS)

    Skoblin, Michael; Chudinov, Alexey; Soulimenkov, Ilia; Brusov, Vladimir; Kozlovskiy, Viacheslav

    2017-07-01

    Numerical simulations of a gas flow through a capillary being a part of mass spectrometer atmospheric interface were performed using a detailed laminar flow model. The simulated interface consisted of atmospheric and forevacuum volumes connected via a thin capillary. The pressure in the forevacuum volume where the gas was expanding after passing through the capillary was varied in the wide range from 10 to 900 mbar in order to study the volume flow rate as well as the other flow parameters as functions of the pressure drop between the atmospheric and forevacuum volumes. The capillary wall temperature was varied in the range from 24 to 150 °C. Numerical integration of the complete system of Navier-Stokes equations for a viscous compressible gas taking into account the heat transfer was performed using the standard gas dynamic simulation software package ANSYS CFX. The simulation results were compared with experimental measurements of gas flow parameters both performed using our experimental setup and taken from the literature. The simulated volume flow rates through the capillary differed no more than by 10% from the measured ones over the entire pressure and temperatures ranges. A conclusion was drawn that the detailed digital laminar model is able to quantitatively describe the measured gas flow rates through the capillaries under conditions considered.

  19. Gas-Liquid Two-Phase Flow Distribution Using Phase Separation Method

    NASA Astrophysics Data System (ADS)

    Zhang, B. D.; Liu, D.; Wang, D.

    2010-03-01

    A method for gas-liquid two-phase flow distribution is proposed in this study, which can be called the phase separation method. The advantage of the new method is that it converts two-phase flow distribution into single-phase distribution, which overcomes the problem of phase splitting in the distribution process of two-phase flow radically, and an equal quality distribution is guaranteed. At first, separate the mixture of gas and liquid into single or near single phase fluids by enhancing phase splitting in distributor, then distribute the single gas and liquid flow respectively as required, finally recombine each couple of gas and liquid stream respectively to form a two phase stream exiting a branch. Experiments were conducted in an air-water multiphase flow test loop. The flow pattern in the experiments included stratified flow, wave flow, slug flow and a part of annular flow. The experimental results show that the phase separation method and apparatus could be feasible to make an equal quality distribution and the deviation of stream quality among the branches is less than 1.6%.

  20. 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.