Showing papers on "Total pressure published in 1989"
TL;DR: In this article, the interaction between impeller blades and diffuser vanes in a diffuser-driven pump was investigated, and the results showed that the turboscale flow coefficient, shaft speeds, and radial gap between the impeller blade and the diffuser vane leading edge increased with increasing radial gap.
Abstract: The interaction between impeller blades and diffuser vanes in a diffuser
pump was investigated. Steady and unsteady pressure measurements were
taken on the diffuser vanes, and the shroud wall of a vaned and a vane less
diffuser. Steady, unsteady, and ensemble averaged unsteady data, as well as
frequency spectra are presented. The measurements were made for different
flow coefficients, shaft speeds, and radial gaps between impeller blade
trailing and diffuser vane leading edge (1.5% and 4.5% based on impeller
discharge radius). The resulting lift on the vane, both steady and unsteady,
was computed from the pressure measurements at mid vane height. The
magnitude of the fluctuating lift was found to be greater than the steady
lift. The pressure fluctuations were larger on the suction side than on the
pressure side attaining their maximum value, of the same order of magnitude
as the total pressure rise across the pump, near the leading edge. Pressure
fluctuations were also measured across the span of the vane. and those near
the shroud were significantly smaller than those near the hub. The pressure
fluctuations on the shroud wall itself were larger for the vaned diffuser than
a vaneless diffuser. Lift, vane pressure, and shroud wall pressure fluctuations
decreased strongly with increasing radial gap.
121 citations
TL;DR: In industrial bioreactors, levels and gradients of total and partial pressures are considerably higher than on the laboratory scale, and increased O2 partial pressure is toxic to aerobic cultures and inhibits microbial growth and product formation.
Abstract: In industrial bioreactors, levels and gradients of total and partial pressures are considerably higher than on the laboratory scale In the relevant range (in general up to 2 or 3 bar, maximum approx 10 bar), effects of total pressure on aerobic cultures are neglegibly small CO2 partial pressures of more than approx 100 mbar may have inhibitory effects on aerobic cultures Growth of aerobic cultures can be enhanced by O2 partial pressures higher than 210 mbar (corresponding to air at 1 bar), if oxygen transfer is limited In many cases, however, increased O2 partial pressure (higher than approx 1 bar) is toxic to aerobic cultures and inhibits microbial growth and product formation Stepwise and cyclic variations of O2 partial pressure may have positive or negative effects, depending on strain of microorganism, culturing conditions, and range of dissolved oxygen concentration
106 citations
TL;DR: A dynamic method is proposed for kla measurement in aerated and agitated reactors, in which achange in the total pressure in the reactor by approximately 20% leads to a simultaneous change in the oxygen concentration in all the bubbles in the dispersion, suppresses the influence of nonideal mixing of the gas phase on the kla value.
Abstract: A dynamic method is proposed for kla measurement in aerated and agitated reactors, in which a change in the total pressure in the reactor by approximately 20% leads to a simultaneous change in the oxygen concentration in all the bubbles in the dispersion. This procedure suppresses the influence of nonideal mixing of the gas phase on the kla value. Other dynamic methods so far used do not possess this advantage. They are based on a step change in oxygen concentration in the entering gas, where the interfacial nitrogen transport and the finite rate of the concentration change propagation into the individual bubbles in the dispersion can cause an error in the reported kla values of more than hundreds of percent. The reliability of the pressure method is tested by comparison both with the standard dynamic method, in which pure oxygen is absorbed in a liquid from which all other gas components were previously removed, and with the steady-state sulphite method. The signal of the oxygen probe used in the experiments must be independent of the pressure. A test for this in dependence is described. The pressure method is also suitable for large-scale reactors since the necessary pressure changes are sufficiently small and, morever, air can be used.
95 citations
TL;DR: In this article, phase-pure orthorhombic YBa 2 Cu 3 O x was obtained by keeping the ratio of O 2 to evolved CO 2 above 50 to ensure phase purity.
90 citations
Patent•
11 Dec 1989TL;DR: In this paper, a combination air data probe performs a number of different pressure measurements from a single structure, which renders these measurements substantially insensitive to aircraft angle of attack (AOA).
Abstract: A combination air data probe performs a number of different pressure measurements from a single structure Measurements of total pressure and total temperature are performed in an improved structural configuration which renders these measurements substantially insensitive to aircraft angle of attack Static temperature is computed free of recovery factor error because of compensatory effects in the pressure and temperature signals Another part of the probe provides measurement of static pressure and pressures for determining angle of attack
65 citations
TL;DR: In this paper, the authors investigated the deposition behavior of GaAs in the Ga-HCl-AsH3-H2 system and found that the earlier reported reduction in growth rate with total pressure is reversed below 104 Pa.
62 citations
TL;DR: In this paper, a miniature five-hole pressure probe was developed to measure three mean velocity components using a non-nulling procedure at individual locations in a curved channel where differential pressures are low, flow is three-dimensional and laminar, and spatial resolution and flow blockage effects are important considerations.
Abstract: A miniature five-hole pressure probe is described which has a probe tip diameter of 122 mm The probe was developed to measure three mean velocity components using a non-nulling procedure at individual locations in a curved channel where differential pressures are low, flow is three-dimensional and laminar, and spatial resolution and flow blockage effects are important considerations Calibration coefficients are presented for Reynolds numbers based on probe tip diameter ranging from 80 to 400 Coefficients for yaw angle, pitch angle, total pressure and total minus static pressure are independent of Reynolds number within experimental uncertainties Experimental details unique to the use of the miniature probe are also given along with distributions of mean velocity and mean vorticity over a portion of the 127 mm*5080 mm cross section of a curved channel At a Dean number of 119 (mean streamwise velocity approximately 12 m s-1), structural characteristics of Dean vortices are evident from contours of the streamwise velocity, the total pressure and the streamwise component of mean vorticity determined from secondary flow vectors
62 citations
01 Oct 1989
TL;DR: In this paper, an ion-drag pump in a vertical, axisymmetric configuration was built, where the ions were injected into the fluid where the viscous shear stresses were the highest.
Abstract: An ion-drag pump in a vertical, axisymmetric configuration was built. Two pumping sections with 1 and 10 electrode pairs were constructed. The total length of the pumping loop with one electrode pair was 133.0 cm; with 10 electrode pairs it was 186.0 cm. The electrodes were designed from the fluid mechanics standpoint. The ions were injected into the fluid where the viscous shear stresses were the highest. The fluid used was dodecylbenzine, and all the experiments were conducted at 25 degrees C. Pumping velocities as high as 33.4 cm/s (corresponding mass flow rate of 1.1 kg/s and total pressure generation of 111.9 Pa) at 25 kV have been achieved. The highest pump power efficiency obtained was 6.0%. The effect of the electrical conductivity level of dodecylbenzine on the pump performance was also studied. Increasing the conductivity level reduced the pumping velocity. >
38 citations
CERN1
01 May 1989-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the light emission from avalanches in parallel-plate chambers, filled with noble gases and with TEA, TMAE, and H2O vapours at a total pressure p = 1 atm under the condition of low gas gain, has been investigated.
Abstract: The light emission from avalanches in parallel-plate chambers, filled with noble gases and with TEA, TMAE, and H2O vapours at a total pressure p = 1 atm under the condition of low gas gain, has been investigated. Three important results have been obtained. 1. (1)|At partial pressures of more than a few Torr, and for a given charge gain, the light output from TEA, TMAE, and H2O in the spectral region 200–700 nm is much higher than from all other common quenching gases. 2. (2)|For these vapours, the ratio of light to charge is independent of their concentration when their partial pressure is more than a few Torr. 3. (3)|The best energy resolution achieved with the light-emitting chamber is ∼18% for 5.9 keV. Qualitative models explaining these results are given.
34 citations
01 Apr 1989-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the carbothermic reduction of alumina was studied in the temperature range of 1700°C to 1850°C in the presence of either tin or copper as the metallic solvent.
Abstract: The carbothermic reduction of alumina was studied in the temperature range of 1700°C to 1850°C in the presence of either tin or copper as the metallic solvent. The total pressure in the smelting system was controlled at pressures between 0.08 and 0.20 atm. The overall reaction is Al2O3(s)+3C(s)=2Al+3CO(g). The rate of reduction of alumina was found to depend strongly on temperature, increasing by three orders of magnitude between 1700°C and 1850°C. Total pressure and activity of aluminum in the solvent bath also affected the rate of reduction. Changes in the alumina particle type and size, in the carbon type, in the carbon-to-oxygen ratio, and in the pellet size had little effect on the rate of reduction of alumina. The kinetics of reduction are shown to follow a pseudo-first order kinetic model.
31 citations
TL;DR: In this article, the authors showed that the growth rate for a rapid thermal process (RTP) system working at a total pressure of a few Torr, obtained selective epitaxial growth (SEG) of silicon at temperatures as low as 650°C.
TL;DR: In this paper, a simple hydrofrac model is proposed to estimate the effects and to derive crustal stresses on the basis of fracture mechanics, which will allow the estimation of the pressure drop at the fracture inlet and the pressure distribution within the hydraulic fracture.
TL;DR: In this paper, the kinetics of the low pressure of methanol from feed gases containing solely CO and H2 were studied in an internally recycled gradientless reactor, where the total pressure was varied from 3 to 7 MPa and the temperature from 503 to 553 K. A maximum likelihood approach was used to fit possible kinetic equations.
TL;DR: In this article, the use of selfaligned chemically vapour deposited tungsten for filling of contact holes and thus for planarization is demonstrated and the best results are obtained in a clean and leak-tight deposition system with a high pumping speed using high H 2 flows (1000 standard cm 3 H 2 min −1 with H 2 :WF 6 = 120:1) and a temperature-ramped deposition process which starts at 300 K.
TL;DR: In this article, the authors used the Nelder- Mead technique to minimize an objective function based on the total pressure of pure α-pinene and correlated the data by using the Antoine equation.
TL;DR: In this paper, the authors describe some of the kinetic results as observed in a rapid thermal processing reactor, working at a total pressure of a few Torr, where the two systems dichlorosilane and silane both diluted in hydrogen, are presented and discussed.
Abstract: Several investigations have been deveted to silicon epitaxial chemical vapor deposition (CVD) under reduced or low pressure conditions. The aim of these activities is to obtain device quality silicon layers at temperatures well below those generally used in CVD at atmospheric pressure (i.e. above 1000 °C). Kinetic aspects can vary according to the pressure regime. Hence, the reacting gas decomposition, in addition to the by-product formation, is affected by the total reactor pressure. According to the literature, silicon selectivity can only be obtained by the addition of hydrochloric gas during the reaction. The possibility of selectivity without the addition of this gas is presented. We describe some of the kinetic results as observed in a rapid thermal processing reactor, working at a total pressure of a few Torr, where the two systems dichlorosilane and silane both diluted in hydrogen, are presented and discussed. Some of the most recent experimental developments are schematically described in addition to their most impressive results. The importance of the silicon surface preparation prior to deposition is reviewed, together with the structural defects induced on the epitaxial layer. Doping redistribution is shown as one of the most relevant parameters leading to the low temperature process. Other structural effects such as loading effects or selective epitaxial growth are presented.
TL;DR: In this paper, the etch rates of GaAs and AlxGa1−xAs were investigated as a function of time (1-12 min), gas flow rate (5-25 sccm), total pressure (4-30 mTorr), plasma power density (0.56-1.32 W cm−2), and percentage of C2H6 in the discharge (10%-50%).
Abstract: The etch rates of GaAs and AlxGa1−xAs (x=0.09–1) in C2H6/H2 were investigated as a function of time (1–12 min), gas flow rate (5–25 sccm), total pressure (4–30 mTorr), plasma power density (0.56–1.32 W cm−2), and percentage of C2H6 in the discharge (10%–50%). The etch rates are constant with time, and decrease with increasing Al content in the AlGaAs. The maximum etch rates occur at 25% by volume C2H6 in H2 and increase linearly with increasing power density. Increasing the total pressure at constant gas composition reduces the etch rates by approximately a factor of 2 between 4 and 30 mTorr. The etched surfaces have smooth morphologies for C2H6 concentrations less than ∼40% of the total gas volume. A layer of subsurface dislocations approximately 40 A deep were observed in GaAs by transmission electron microscopy for the highest‐power density discharges, while the surfaces for all samples are As‐deficient to a depth of ∼30 A after reactive ion etching. Polymer deposition is not significant for C2H6 volum...
Patent•
06 Dec 1989
TL;DR: In this article, a sensor for detecting trace or impurity gases is proposed, which consists of a mixture of gases containing both oxygen and an inert gas at a total pressure of not less than 100 pascals.
Abstract: A method of manufacturing a sensor for detecting trace or impurity gases, the method comprising evaporating tin and/or tin oxides under a partial pressure of oxygen in order to condense vapor on an electrically insulating substrate to obtain a porous layer deposit therein. The metal or the metal oxides is/are evaporated under a flow of a mixture of gases containing both oxygen and an inert gas at a total pressure of not less than 100 pascals and with the partial pressure of the oxygen in the mixture being not more than 130 pascals.
TL;DR: In this paper, the vacuum work function of chemically vapor deposited (CVD) rhenium was investigated and it was concluded that residual gas pressure was responsible for conflicting work function data.
Abstract: The vacuum work function of chemically vapor deposited (CVD) rhenium was investigated. The thermionic emission technique was used in order to obtain high temperature data. Data were collected as a function of temperature and time, and the total pressure was recorded. X-ray analysis showed that the rhenium was preferentially deposited with the 0001 planes approximately parallel to the emitting surface. The effective work function data were compared with the results of Campbell et al. [1]. It was concluded that the residual gas pressure was responsible for conflicting work function data.
TL;DR: In this article, the applicability of a bremsstrahlung counting method was examined by using an apparatus for supply and recovery of highly concentrated tritium gas, and a newly designed proportional counter showed a considerably high sensitivity.
01 Jan 1989
TL;DR: Although the etiologies of stenoses appearing in various parts of the cardiovascular system may differ, their effects on blood flow can be summed up in a single term, pressure loss.
Abstract: Although the etiologies of stenoses appearing in various parts of the cardiovascular system may differ, their effects on blood flow can be summed up in a single term, pressure loss.
01 Sep 1989
TL;DR: In this paper, the vacuum work function of chemically vapor deposited (CVD) rhenium was investigated and it was concluded that residual gas pressure was responsible for conflicting work function data.
Abstract: The vacuum work function of chemically vapor deposited (CVD) rhenium was investigated. The thermionic emission technique was used in order to obtain high temperature data. Data were collected as a function of temperature and time, and the total pressure was recorded. X-ray analysis showed that the rhenium was preferentially deposited with the 0001 planes approximately parallel to the emitting surface. The effective work function data were compared with the results of Campbell et al. [1]. It was concluded that the residual gas pressure was responsible for conflicting work function data.
TL;DR: In this article, an optimal design program of an axial-flow compressor stage was developed by applying the gradient projection method to a simulation program, where the authors considered the axial flow path tends to be deflected radially outward and axial velocity is decreased both in the rotor and the stator.
TL;DR: In this paper, the chemical steps of the Si and SiC deposition from DCS/H2 and MTS/H 2 respectively, are approached on the basis of a calculation of the homogeneous equilibria.
Abstract: The chemical steps of the Si and SiC deposition from DCS/H2 and MTS/H2 respectively, are approached on the basis of a calculation of the homogeneous equilibria. SiCl2 appears to be a major intermediate species in both cases. Supersaturation is found to be very high particularly at low temperature. A calculation of the heat, momentum and mass transfers performed for the DCS/H2 system, is used to validate the choice of the experimental CVD-chamber/substrate assembly (isothermal hot zone reactor, cylindrical geometry). The variations of the deposition rate vs the reciprocal temperature, gas flow rate and total pressure show the occurrence of transitions between CVD processes controlled either by surface reactions, mass transfers or thermodynamic factors.
Patent•
01 Feb 1989
TL;DR: In this article, a blowdown water pressure adjusting means formed with a fine tube 10 is provided on the upstream side of the fixed throttle 9 of the blowdown circuit, provided on a steam separator 5 for discharging inner storage water.
Abstract: PROBLEM TO BE SOLVED: To stably continue an operation for a long period, without reducing the flow rate of blowdown water by providing a blowdown water pressure adjusting means formed with a fine tube having a cross sectional area smaller than that of a main pipe on a blowdown circuit. SOLUTION: A blowdown water pressure adjusting means formed with a fine tube 10 is provided on the upstream side of the fixed throttle 9 of a blowdown circuit, provided on a steam separator 5 for discharging inner storage water. The blowdown circuit has an inlet pressure of about 0.7 MPa and outlet pressure of about 0.1 MPa. When a fine tube 10 with the inner diameter of 1 mm and the length of 2 (m), for example, is used as the blowdown water pressure adjusting means of a 100-kW class fuel cell power generating system, about 0.36 MPa within the total pressure drop of about 0.6 MPa of the blowdown circuit is shared by the fine tube 10. The pressure drop to be shared by the fixed throttle 9 is significantly reduced from about 0.6 MPa to about 0.24 MPa, and a flush quantity is reduced. The blowdown water stably flows, without causing the sticking or deposition of foreign matters.
04 Jun 1989
TL;DR: In this article, a study on the design and off-design loss and deviation correlations was performed in which transonic compressor test data of 1970's was used, and a modified version of NASA-2D minimum loss incidence correlation was proposed for DCA and MCA blades.
Abstract: A study on the design and off-design loss and deviation correlations was performed in which transonic compressor test data of 1970’s was used. Losses are considered as a whole and expressed by a total pressure loss coefficient with design and off-design parts identified separately. A modified version of NASA-2D minimum loss incidence correlation is proposed for DCA and MCA blades. Koch and Smith design loss correlation was found to be most satisfactory. For DCA and MCA blade profiles new off-design loss correlations were formulated. A correction is proposed to the Carter’s design deviation angle prediction method. For off-design deviation prediction Creveling’s correlation is easy to apply and gives most consistent and successful results.Copyright © 1989 by ASME
Patent•
08 Dec 1989
TL;DR: In this article, a method was proposed to improve mechanical strength, moisture-resistance and alkali ion barrier properties by a method wherein a first layer insulating film was formed under first pressure conditions with a higher pressure by a plasma vapor growth method and, successively, a second layer insulation film was created under second pressure conditions under a lower pressure.
Abstract: PURPOSE:To improve mechanical strength, moisture-resistance and alkali ion barrier properties by a method wherein a first layer insulating film is formed under first pressure conditions with a higher pressure by a plasma vapor growth method and, successively, a second layer insulating film is formed under second pressure conditions with a lower pressure. CONSTITUTION:After a total pressure is set by introducing monosilane gas, ammonia gas and diluting nitrogen gas, a discharge voltage is applied to form a first plasma silicon nitride film 104 by a plasma vapor growth method. Then, after only the total gas pressure is set to a pressure lower than the first pressure, a second plasma silicon nitride film 105 is formed. The second plasma silicon nitride film 105 formed under such pressure conditions is a precise film having a higher density than the first plasma silicon nitride film 104. With this constitution, a plasma silicon nitride film having excellent protective film characteristics can be obtained.
04 Jun 1989
TL;DR: In this article, an analytical expression was developed which relates radial components of the total pressure gradient near the wall to the passage geometry, tip speed, skew, throughflow and wall skin friction coefficient.
Abstract: The interaction of tip leakage and the rotor passage secondary flow is examined. An analytical expression is developed which relates radial components of the total pressure gradient near the wall to the passage geometry, tip speed, skew, throughflow and wall skin friction coefficient. This expression provides a correlation with the differences observed in the passage secondary velocity patterns associated with tip clearance gaps in experimental compressors. The analysis is qualitatively supported by comparison with secondary flow velocity measurements from a small sample of published test data.Copyright © 1989 by ASME
01 Dec 1989-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a new pack cementation process is reported where the substrates are treated in the gas phase, over a pack, in a semi-open chamber maintained under reduced pressure.
Abstract: A new pack cementation process is reported where the substrates are treated in the gas phase, over a pack, in a semi-open chamber maintained under reduced pressure. A stable halide is always present in the condensed state in the chamber and the process is controlled by the metal activities in the pack, the total pressure and the temperature of the treatment. It is applied here to the aluminization of massive substrates and external and internal surfaces of pure nickel and nickel alloy tubes, but it can be extended to various geometries such as complex-shaped substrates or porous materials. The conditions necessary to increase the gaseous transport rate are deduced from a gaseous diffusion model which takes into accout the Knudsen diffusion contribution at the lower pressures, inside tubes or narrow cavities. The intrinsic diffusion rates in the gas phase are compared with the intrinsic solid state diffusion rates under various conditions of aluminization ranging from high to low aluminium activity, total pressure and temperature ranging from 0.3 to 760 Torr and from 670 to 950 °C respectively. It is shown how these parameters can be varied in conjunction to obtain a uniform coating on a given geometry. Finally, parts to be coated are classified into two groups depending on whether the Knudsen diffusion is negligible or not. This process extends to the transport of other metals and some co-transport.
18 Sep 1989
TL;DR: The NDA's 0.06-m*0.3m wind tunnel was constructed in 1985 for testing transonic airfoils and for other basic research of fluid mechanics.
Abstract: The NDA's (National Defense Academy of Japan) 0.06-m*0.3-m cryogenic wind tunnel was constructed in 1985 for testing transonic airfoils and for other basic research of fluid mechanics. Stainless steel SUS 304 was chosen as the material of the pressure shell, and a centrifugal compressor was chosen as the compressor. External insulation was adopted for the tunnel. Although no information was available on problems of using SUS 304 as the externally insulated tunnel pressure shell at cryogenic temperature and the thermal conductivity of SUS 304 is worse than that of aluminium alloys, only eight thermocouples were installed to monitor the thermal condition of the shell. The original temperature control was achieved by manually controlling the mass flow of liquid nitrogen injected into the tunnel circuit, but that system was found to be inadequate because the settling time of the total temperature took about 15 min in the change of rotational speed of the compressor. The total pressure control systems were modified to simple automatic PID (proportional, integral, derivative) controls. As a result, the pressure control can be achieved almost perfectly, and the temperature control is also greatly improved as the settling time of temperature is greatly reduced. >