Showing papers on "Total pressure published in 1980"

Diffusion pumping apparatus self-inflating device

Abstract: An elastomeric enclosure is initially inflated to a desired pressure by a gas having large molecules incapable of diffusing outwardly from the enclosure, except at a relatively slow rate. When the enclosure is surrounded by ambient air at atmospheric pressure, such air passes into the enclosures by reverse diffusion, thus extracting energy from the ambient sea of air to progressively increase the total pressure in the enclosure to a substantial extent over a period of several months, the pressure then decreasing very slowly over an extended period to its initial inflation pressure, such extended period being as much as about two years or more. This added energy may be used to perform useful work or used in various pneumatic devices to achieve essentially permanent inflation. Decrease in pressure below the initial inflation value continues at a very slow rate over an additional period of many months, and, in fact, several years, with the inflation pressure still remaining at a sufficiently high value which enables the inflated enclosures to still possess a useful life.

Reactive‐ion etching of GaAs and InP using CCl2F2/Ar/O2

Abstract: We describe the reactive ion etching of GaAs, InP, and their derivative compounds using an etch gas composed of CCl2F2, O2, and argon. Etching was generally carried out at pressures between 1 and 10 μ, and power densities below 0.8 W/cm2. Clean etch profiles were obtained with etch rates as high as 0.25 μm/min. A strong dependence of etch rate on pressure was observed with a maximum at 5 μ total pressure. The etch profiles exhibited a ’’negative undercut’’ character which was also dependent upon the total pressure.

On the kinetics of the chlorination of titanium dioxide in the presence of solid carbon

Abstract: The influence of solid carbon on the chlorination of TiO2 with Cl2 and CO-CO2-Cl2 gas mixtures was investigated gravimetrically using rutile and graphite tablets. In the experiments, the temperature, composition and total pressure of the gas phase as well as the TiO2-C separation were varied. The chlorination rate of TiO2 was found to be 40 to 50 times faster with TiO2-C contact than in the absence of carbon. The acceleration of the chlorination rate is due to the kinetic influence of solid carbon and takes place even when TiO2 and C are separated by the gas phase. In the latter case the C influence decreases with increasing TiO2-C separation. In the case of flowing Cl2-Ar mixtures at 105 Pa total pressure this influence exists within a critical TiO2-C separation,L, which is approximately 40 μm at 1273 K and PCl2 = 2.7 × 104 Pa.L increases linearly with increasing temperature and decreases approximately linearly with increasing total gas pressure in the case of a closed reaction vessel. The ratio of the reacted amounts of TiO2 and C is also dependent on the TiO2-C separation. From the experimental results a kinetic reaction model is proposed to provide a quantitative description of the influence of solid carbon. The dependence of the chlorination rate,i, of TiO2 on the TiO2-C separation,l, is given byi ∼ (l + Β) −2 whereΒ is a constant.

Oxidation of an aluminum magnetron sputtering target in Ar/O2 mixtures

Abstract: The oxidation kinetics during sputtering of an Al target in a planar magnetron have been studied by accurate measurement of the total pressure produced by argon/oxygen mixtures. When a 5×8‐in. target is rf sputtered at 500 W with a fixed argon flow, the pressure is constant at 4.6 mTorr until the oxygen flow rate is increased to 2.1 cm3/min. At this critical flow, the total pressure increases to 7.85 mTorr in 100 min and the time dependence is explained by a parabolic oxidation rate. The equilibrium oxide thickness is about 100 nm and has been measured by determining the time necessary to cause a sudden increase from 180 to 290 V in self‐bias voltage. When the target was oxidized, Al2O3 films were deposited at 3 nm/min, whereas Al was deposited in an argon discharge at 70 nm/min. The ratio in sputtering rates of Al and Al2O is a factor of 2 greater than predicted from calculated yield values. Before target oxidation, oxygen added to the system is gettered by the film until, at values just below the critical value, Auger analysis shows the films have a composition AlOx where 1

An empirical model of the Venusian outer environment 1. The shape of the dayside solar wind-atmosphere interface

Abstract: Solar wind plasma and magnetic field data and ionospheric data obtained from the Pioneer Venus orbiter are discussed. The variation in the magnetic field pressure within the magnetic barrier is shown to be similar to that expected for the solar wind pressure variations along an obstacle's boundary when a more realistic approximation of the shape of the ionosphere is included. Simultaneous solar wind pressure, ionospheric pressure, and magnetic barrier pressure data reveal that the ionospheric pressure below the ionopause is approximately equal to the solar wind pressure. The magnetic barrier pressure is found to be equal to approximately 2/3 to 3/4 of both the solar wind pressure and the ionospheric pressure. Estimates of the hot plasma pressure contribution to the total pressure in the magnetic barrier vary from 1/4 to 1/3. Just below the ionopause the ionospheric pressure deviations from the mean ionospheric pressure are significant, especially below approximately 400 km; they appear to be indicative of the adjustment of the ionospheric structure to changeing solar wind conditions. A first-order model of the ionopause pressure variations as a function of height and solar-zenith angle is proposed. Venera 9 and Venera 10 bow shock crossings are then analyzed for solar zenith angles in the range from approximately 25 deg to approximately 153 deg. A comparison of Venera 9 and Venera 10 bow shock crossings with those observed by the Pioneer Venus orbiter suggests that both the secular variation and the latitudinal asymmetry may be responsible for the closer shock crossings of the Venera 9 and Venera 10 spacecraft.

Flow sensing apparatus

Abstract: A flow sensing apparatus having increased sensitivity is disclosed for sensing the flow of gas, particularly through a confined passage such as the ducts in heating, ventilating and air conditioning systems. The flow sensing apparatus comprises a tube divided by a wall into an upstream chamber and a downstream chamber. The upstream chamber can have a constant orifice but preferably the walls of the tube in the upstream end are tapered to form a tapered chamber section. A total pressure sensing probe is located in the center of the tube and has its opening in the upstream chamber of the tube. The total sensing probe has its opening parallel to the flow of gas and facing upstream, the opening of the total pressure sensing probe preferably being in the wall dividing the tube into the upstream and downstream chambers. A static pressure sensing probe is located in the downstream chamber. The static pressure probe may be located in the walls of the tube and have its opening perpendicular to the flow of gas. Alternatively the static pressure probe may be located in the wall dividing the tube into chambers with its opening parallel to the flow of gas and facing downstream. The sensing probes may be connected to a measuring device that provides a readout of the sensed pressures or pressure differential or to a control unit that is responsive to the sensed pressures or pressure differential.

Aerodynamic Loss in a Gas Turbine Stage with Film Cooling

Abstract: Experiments have been performed to measure the total pressure loss of the flow through a two-dimensional turbine cascade with “coolant” injection from a single row of holes on the suction or pressure side of the blades. The tests were performed in a low speed tunnel. Air and carbon dioxide were used as secondary fluids, the latter to provide a large density difference between the gas in the mainstream and the injected gas. Both gas streams had the same temperature. The measured pressure loss is in good agreement with analytical predictions based on a model introduced by Hartsel. The results thus provide information which can be incorporated in a program which predicts the influence of injection on the aerodynamic efficiency of a gas turbine.

Effect of Swirl on Pressure Recovery in Annular Diffusers

Abstract: Annular diffusers are likely to operate with varying amounts of swirl at the inlet. The work described in this paper is concerned mainly with an experimental investigation of subsonic turbulent swirling flows through annular diffusers having diverging hub and casing boundaries. The test facility was designed SO as to peImit different levels of inlet swirl. The static pressure distributions and the axial and tangential velocity profiles were measured with the help of a three-hole cobra probe suitably mounted at different cross sections along the diffuser length. The diffuser performance parameters such as static-pressure recovery, effectiveness, and the total pressure loss coefficient were then computed from the experimental observations. The behaviour of these parameters has been discussed to establish the effect of swirl. The presence of inlet swirl was found to increase the overall static-pressure recovery. A substantial increase in the pressure recovery occurred over the initial stages of diffusion and...

Method and apparatus for controlling a gas turbine engine

Abstract: A gas turbine engine control for an engine which experiences airflow distortion at the engine inlet face plane uses a static pressure measurement upstream of the face plane along with a corrected rotor speed to generate a signal indicative of the average total pressure at the engine face plane. This signal is combined with a total pressure signal from elsewhere in the engine to generate a pressure ratio signal which is compared to the scheduled pressure ratio for the current operating conditions. Control logic then adjusts either the fuel flow rate to the burners or the area of the exhaust nozzle in response to the difference between these pressure ratios.

Combined pressure and temperature distortion effects on internal flow of a turbofan engine

Abstract: An additional data base for improving and verifying a computer simulation developed by an engine manufacturer was obtained. The multisegment parallel compressor simulation was designed to predict the effects of steady-state circumferential inlet total-pressure and total-temperature distortions on the flows into and through a turbofan compression system. It also predicts the degree of distortion that will result in surge of the compressor. The effect of combined 180 deg square-wave distortion patterns of total pressure and total temperature in various relative positions is reported. The observed effects of the combined distortion on a unitary bypass ratio turbofan engine are presented in terms of total and static pressure profiles and total temperature profiles at stations ahead of the inlet guide vanes as well as through the fan-compressor system. These observed profiles are compared with those predicted by the complex multisegment model. The effects of relative position of the two components comprising the combined distortion on the degree resulting in surge are discussed. Certain relative positions required less combined distortion than either a temperature or pressure distortion by itself.

Coal gasification process

Abstract: A process for gasifying coal and other carbonacaeous matter is disclosed which produces fuel gas containing low concentrations of polycyclic aromatic hydrocarbons. In this process the polycyclic aromatic hydrocarbons released by the coal during devolatilization and formed during pyrolysis of volatile matter are decomposed thermally in the presence of hydrogen, at a sufficiently high partial pressure (obtained by increasing the total pressure in the gasifier) to prevent polymerization of free radicals formed during pyrolysis. A relationship between the temperature, the gas residence time in the gasification reactor, the hydrogen partial pressure (i.e., total pressure in the gasifier), and the coal feed conditions are specified to achieve "clean" coal gasification.

Efficient operation of Blumlein‐discharge‐excited XeCl laser

Abstract: Experimental results of a Blumlein‐discharge‐excited XeCl laser are reported in this letter. The maximum output pulse energy was over 400 mJ. The overall efficiency and specific output energy were 1.7% and 5 Jl, respectively. Experiments have shown that the lasing spectrum of XeCl varied with the total pressure. With a total pressure of 500 Torr, 108 discrete laser lines including two new vibrational bands, (0,4) and (1.7), were obtained. The effects of the partial pressure of Xe, the Blumlein charging voltage, and the total pressure on the output energy were also investigated.

Investigation of the flow field surrounding circular-arc boattail nozzles at subsonic speeds

Abstract: The effects of jet exhaust on the subsonic flow field surrounding boattail nozzles with attached and separated boundary layers were investigated. Measurements of local Mach numbers and flow angles were made at free-stream Mach numbers of 0.60 and 0.80 at an angle of attack of 0 deg. Jet exhaust flow was simulated with a solid cylindrical sting and with high pressure air at jet-nozzle total pressure ratios of 2.9 and 5.0. Results show strong effects of the jet-wave structure on the external flow field. The predicted local Mach numbers and flow angles for attached-flow nozzles with solid jet simulators obtained by using subsonic inviscid/viscous-flow theory are in good agreement with experimental data. Prediction of nozzle surface pressure distributions which include jet-entrainment effects also agree with experimental data for attached-flow nozzles with high pressure air jets.

High temperature pressure transducer system

Abstract: A high temperature pressure transducer for measuring the total pressure adjacent the exit orifice of a crucible containing molten metal used in a continuous casting operation is disclosed. The pressure sensed includes a pressure head of the molten metal as well as the gas gauge pressure in the crucible above the metal. The transducer includes a sensor rod assembly having an immersible sensor rod fabricated of fused quartz and having a sensing surface, a sensor rod extension, an intermediate shaft, and a load cell connected to the intermediate shaft. A bellows provides a gas tight seal for the internal gas pressure in the crucible. The bellows is characterized by folds projecting inwardly and outwardly and providing equal volume in the two directions. By having a constant volume, it follows that the surface area of the folds in the two directions is the same so that any pressure changes along the bellows cancels out and does not adversely affect the reading at the load cell thereby assuring an accurate total pressure reading. In addition, a process is disclosed for controlling the flow rate of molten metal from the exit orifice of a closed crucible wherein the total gas and liquid pressure measurement obtained by the high temperature pressure transducer is used as an input into a control circuit which controls the amount of pressurized gas or vacuum applied to the crucible.

Effects of sidewall geometry on the installed performance of nonaxisymmetric convergent-divergent exhaust nozzles

Abstract: The investigation was conducted at static conditions and over a Mach number range from 0.6 to 1.2. Angle of attack was held constant at 0 deg. High pressure air was used to simulate jet exhaust flow at ratios of jet total pressure to free-stream static pressure from 1 (jet off) to approximately 10. Sidewall cutback appears to be a viable way of reducing nozzle weight and cooling requirements without compromising installed performance.

An Evaluation of Statistical Methods for the Prediction of Maximum Time-Variant Inlet Total Pressure Distortion

Abstract: : An analysis was conducted to determine the accuracies and limitations of three statistical methods used to predict engine-face maximum time-variant total pressure distortion. The statistical methods have all been proposed as low-cost alternatives to the time-consuming and costly deterministic method generally used for reducing engine-face time-variant total pressure data. The statistical methods are evaluated by comparing their predicted distortion values and patterns to those measured with the deterministic method. Data comparisons from tests of four different inlet models, covering a wide range of Mach numbers, mass flow ratios, model attitudes, and distortion factors, were used during the analysis. The results show good agreement between the measured and predicted values for all three statistical methods. The distortion pattern predictions, however, were inadequate at conditions with high total pressure fluctuation (turbulence). It is recommended that improvements continue to be made in the statistical methods, particularly adjustments for high-turbulence conditions, and that the Melick method be used as an on-line distortion analysis tool for inlet performance tests.

An Experimental Investigation of Reactive, Turbulent, Recirculating Jet Mixing

Abstract: : An experimental investigation of ducted, two-stream, subsonic, turbulent jet mixing with recirculation was conducted A primary jet of air at a mass flow rate of 0580 1bm/sec and bulk velocity of 335 ft/sec was surrounded by an outer hydrogen stream at a mass flow rate of 0002 1bm/sec and bulk velocity of 3 ft/sec (overall equivalence ratio of 012) The ratio of the duct to inner nozzle diameter was 25 Radial distributions of mean axial and radial velocity, axial and radial turbulence intensity, velocity cross correlation, gas composition, static temperature, and total pressure, as well as axial distribution of wall static pressure, are presented for axial stations from zero to six duct diameters from the nozzle exit plane, both with and without chemical reactions The maximum turbulent intensities which occurred in the center of the mixing layer and within the recirculation eddy were very high, having values in excess of 20 percent of the jet exit velocity The data clearly indicate that the mixing is slower in the chemically reactive flow field than in the nonreactive flow field and that the presence of chemical reactions had a significant effect on the size and location of the recirculation zone within the mixing duct

Estimation of Unsteady Cavitation on Propeller Blades as a Base for Predicting Propeller-Induced Pressure Fluctuations

Abstract: In order to calculate the pressure fluctuations induced by a cavitating propeller, the cavity geometry on the propeller blades must be known as a function of time. Purely theoretical calculation thereof needs application of unsteady lifting surface theory including effect of unsteady cavitation which is, however, far beyond the analytical formulation. In this study, attempts were made to estimate the unsteady cavitation using available theoretical methods (an unsteady theory on non-cavitating propeller and an approximate method of lift equivalence for determination of cavity length). As a result, the unsteady cavitation on the blades was found to be estimated by life equivalence method with some empirical factors obtained by the observation of cavity extent and the measurement of cavity thickness. The pressure fluctuation calculated by thus obtained cavity geometry turned out to be about four times as large as the measured values. Multiplying factor 1/4 with calculated pressure due to unsteady cavity, the correlation between the calculated and the measured total pressure fluctuations was found to be fairly good.

XPS Determination of Amount of Incorporated Rare Gas in Amorphous Silicon Films Produced with Reactive Sputtering Method

Abstract: The incorporation of rare gas into a-Si: H produced by the reactive sputtering method is studied with XPS measurements The amount of neon incorporated in an a-Si: H film prepared in a 93% Ne+7% H2 gas mixture decreases monotonically from 7 atomic % until it becomes undetectable, as the total pressure is increased from 02 Pa to 30 Pa A-Si: H films produced under the same Ne partial pressure without H2 contain ca 17 times as much amount of Ne atoms as those prepared with H2

Manufacture of al containing monodirectional silicon steel sheet with extremely high magnetic flux density

Abstract: PURPOSE:To manufacture the monodirectional silicon steel sheet containing Al permissible high magnetic flux density, by controlling the partial pressure of N2 in the atmosphere at temperatures over through the period ending with completion of the secondary recrystallization is the heating pass for the final annealing process being executed for the cold relled Al containing silicon steel. CONSTITUTION:After hot rolling, annealing and cold rolling the slab of Al containing silicon steel, the final annealing process is executed; hereupon, over through the heating pass, the partial pressure of N2 in the annealing atmosphere of 800-950 deg.C is controlled to under 20% of the total pressure. Hereby, the preparatory layer for coarsening the crystal grain in the skin layer of the sheet is formed. Following to this, the partial pressure of N2 is kept above 3%, preferably above 10%, over through the period from the start of recrystallization to the end point of the secondary recrystallization at 1100 deg.C. As a result of this treatment, the concentration of AlN in the skin layer is appropriately reduced, and the characteristic with high magnetic flux density, that is B8 above 1.90, can be stably obtained.

Production of polyolefin resin molded foam

Abstract: PURPOSE: To obtain a molded article having a precise shape as defined by a mold, by a method wherein a molding die is charged with polyolefin resin preformed particles contg. a mixed gas within cells, and the particles are heated, said mixed gas having a specified total pressure and consisting of an inorg. gas having a specified partial pressure and a volatile blowing agent having a specified particle pressure. CONSTITUTION: A molding die is charged with polyolefin resin (e.g. PE or PP) prefoamed particles contg. a mixed gas within cells, said mixed gas having a total pressure of 1.4W2.5kg/cm 2 (absolute pressure) and consisting of an inorg. gas (e.g. air or nitrogen) having a partial pressure of 0.4W1.1kg/cm 2 (absolute pressure) and a volatile blowing agent (e.g. propane or butane) having a partial pressure of 0.8W1.6kg/cm 2 (absolute pressure). Then the particles are heated to produce a molded article having a precise shape as defined by the mold. The prefoamed particles can be produced in the following manner. The volatile blowing agent and the polyolefin resin particles are dispersed in water within a closed container. The mixture is heated to a temperature not lower than the softening temp. of the particles to impregnate the particles with the volatile blowing agent. Then the pressure within the container is held at a pressure not lower than the vapor pressure of the blowing agent. One end of the container is opened. At the same time the particles are discharged to an atmosphere having a pressure lower than that within the container. COPYRIGHT: (C)1982,JPO&Japio

Vane type fluid machine

Abstract: PURPOSE:To improve efficiency by properly adjusting the force, by which a vane pushes a cylinder perpendicular to its contacting surface at the touching portion between the vane and the cylinder, by using magnetic force. CONSTITUTION:A magnetic force generator 16 is attached to a cylinder 10 at the place where the perpendicular pressure 42 of a vane 13 is improper, e.g. where the perpendicular total pressure 42 becomes zero by depending only on backpressure 43 or where the perpendicular total pressure 42 is so large due to the number of revolutions that its pressure control is required. As the number of revolutions increases, its value is detected by a tachogenerator 35 and compared with the value of a pressure 36, and the difference is amplified by an amplifier 38 to send the signal by which magnetic force is generated in the magnetic force generator 16. Hereby, the total perpendicular pressure 42, when it is too large or too small, can be properly adjusted by bringing the vane 13 apart from or close to the cylinder inner surface 15, respectively.

Fuel discharge device

Abstract: PURPOSE:To stabilize the condition of atomized fuel mist by keeping fuel injected from a fuel injection nozzle at a specific pressure relatively variable with the total pressure of an air flow through an intake pipe. CONSTITUTION:As a pump 19 puts out fuel with constant difference in pressure, a fuel metering device 8a regulates the pressure of the fuel in proportion to that of an air valve 3 to supply it into a fuel outlet device 333. A piston 335 situated at one side of a fuel chamber 334 is applied with a total air pressure of an inlet pipe 1 through the pathes 92, 350 and a load of a spring 336. One end of a piston rod 337 regulates each orifices of the fuel outlet ports 339, 340 so that a difference between a pressure of discharged fuel and a pressure of air may be great and kept constant. This can stabilize the condition of atomized fuel from a swirl chamber 338 to a nozzle end 344.

Investigations of hydrogen gettering by means of mass spectrometry and microgravimetry

Abstract: Experiments were conducted on different bulk getter materials (Ti, Zr, Ce) in order to study their potential in a new gas purification concept for high‐temperature gas‐cooled reactors. Since the removal of hydrogen and tritium represents the main problem, the measurements concentrated on plateau pressures of the metal hydrides, the kinetics of absorption, passivation, and hydrogen isotope effects. The apparatus used for model investigations with H2 and D2 is a UHV device involving two hot metal beds one of which consists of a microbalance system, various total pressure gauges, and a quadrupole mass spectrometer. The absorption rates were found to be linear with pressure, which is consistent with gas kinetic theory. Plateau pressure measurements down to 10−8 mbar confirm extrapolated literature data, while an observed significant isotope effect near ambient temperature may be understood as a specific passivation effect.

Experimental study of fracture at geological scale velocities

Abstract: Summary. It is well-known that the chemical environment and the thermodynamical conditions play a fundamental role in the physics of the fracture properties of solids which in turn appear relevant in the understanding of the earthquake mechanism and related precursory phenomena. We designed and built an experimental apparatus capable of measuring the fracture velocities with control of the physical and chemical environment as well as of the applied stress. The apparatus consists of a chamber where both the total pressure and the partial pressure of gases can be controlled. The stress is applied in mode I (tension) configuration. The crack is detected optically on the surface of the sample with an ordinary microscope and the velocity of propagation is directly measured by the increase in length in the elapsed time. The very good stability of the system over very long periods allows us to measure crack velocities down to 10−12 ms−1. The propagation under such low-velocity regimes appears interesting from a geological standpoint since it implies extremely low stress values, which are generally assumed to have no effect on crustal rocks. The first results obtained will be discussed, with particular regard to the apparent dramatic influence of the partial pressure of water vapour in the crack propagation velocity.

Detection method of gas flow rate

Abstract: PURPOSE:To enable accurate measurement, by taking clean gas for purge as measuring object, in the flow speed detection method for gas including dust by means of pitot tube system using a thermal wire flow meter. CONSTITUTION:With the valves 8, 9 closed and the valves 7, 10 open, the purge gas flows to the total pressure leading tube 3 and still pressure leading tube 4 to perform gas purge to the tip of the pitot tube 2. Further, the valves 7 and 10 are closed to keep equal the pressure of purge gas remained in the pitot tube 2 and the leading tubes 3 and 4 to the pressure if the liquid in the gas duct 1. After that, when the valves 8 and 9 are opened, the differential pressure caused with the pitot tube 2 causes the flow of purged gas in the measuring tube 22, allowing to measure it with the thermal wire flow speed meter 11 and the thermal wire sensor 12. This flow signal and the signal in proportion to the temperture and pressure of the fluid in the gas duct are inputted to the operation unit 19 to calculate the flow speed of the fluid in the duct.

Simulation of Coal Conversion Reactor Environments

Abstract: Two models simulating the coal gasifier environment are described; Model 1 comprises coal gas components and a molten sodium salt phase, while Model 2 also includes a solid carbon phase. The use of equilibrium constants to compute the equilibrium state of an open system and the occurrence of multiple equilibrium states are detailed. Representative computations pertaining to the two models are shown in which dependent partial pressures and activity ratios are computed as function of temperature, total pressure, and the partial pressures of hydrogen, carbon monoxide, and hydrogen sulfide. The dominant anion in the liquid phase is mapped as a function of equilibrium gas phase composition.