Total pressure

About: Total pressure is a research topic. Over the lifetime, 5199 publications have been published within this topic receiving 66658 citations.

On finite β stabilization of the toroidal ion temperature gradient mode

Abstract: It is shown that finite beta stabilization of the toroidal ion temperature gradient (ITG) mode is attributable to the electron ballooning parameter (normalized electron pressure gradient) αe. A modest αe, much smaller than that required from the drift reversal α (normalized total pressure gradient) ≳2q2 where q is the safety factor, can effectively stabilize the ITG mode.

Influence of loading distribution on the performance of transonic high pressure turbine blades

Abstract: Midspan measurements were made in a transonic wind tunnel for three high pressure turbine blade cascades at design incidence. The baseline profile is the midspan section of a high pressure turbine blade of fairly recent design. It is considered mid-loaded. To gain a better understanding of blade loading limits and the influence of loading distributions, the profile of the baseline airfoil was modified to create two new airfoils having aft-loaded and front-loaded pressure distributions. Tests were performed for exit Mach numbers between 0.6 and 1.2. In addition, measurements were made for an extended range of Reynolds numbers for constant Mach numbers of 0.6, 0.85, 0.95, and 1.05. At the design exit Mach number of 1.05, the aft-loaded airfoil showed a reduction of almost 20% in the total pressure losses compared with the baseline airfoil. However, it was also found that for Mach numbers higher than the design value the performance of the aft-loaded blade deteriorated rapidly. The front-loaded airfoil showed generally inferior performance compared with the baseline airfoil.

Laser‐induced fluorescence of gaseous UF6 in the A–X̃ band

Abstract: The A–X band of gaseous UF6 has been studied using the laser‐induced fluorescence technique. Excitation and fluorescence spectra are presented for various pressures of UH6 at room temperature. The fluorescence spectra show little change over the pressure range 0.2–20 torr, with a peak wavelength at 421 nm. In contrast, the peak wavelength of the excitation spectra shows a noticeable shift from 391 to 385 nm when the UF6 pressure is increased from 2 to 20 torr. A Stern–Volmer plot of UF6 self‐quenching data shows a pronounced nonlinear behavior over this same pressure region. From an analysis of the laser‐induced fluorescence spectra, we develop a simple kinetic model for UF6 excited‐ state dynamics. A standard kinetic treatment of this scheme yields a prediction for the dependence of the fluorescence decay lifetime on total pressure that is in good agreement with experimental results.

Germination and Growth of Spinach under Hypobaric Conditions

Abstract: In a plant production facility designed for human life support in vacuum space, lowering total air pressures within the facilities is expected to have the engineering advantage of reducing the construction cost. In this study, low total pressure treatments were applied to spinach over the entire production period from seeding to harvest. An environment control system was constructed to grow plants under low total pressure for long durations. Spinach seeds were directly sowed on a hydroponic plant bed placed in a reduced-pressure growth chamber. The total and O2 partial pressures within the growth chamber were set at 101 and 21 kPa, 25 and 21 kPa, and 25 and 10 kPa, respectively. The CO2 partial pressure was constant at 40 Pa. At 21 kPa of O2 partial pressure, there were no significant differences in fresh and dry weights, leaf area, and shoot length of spinach at harvest between 101 and 25 kPa of total air pressure. At 10 kPa of O2 partial pressure and 25 kPa of total pressure, the dry weight was not affected, but the leaf area and shoot length at harvest were smaller than those at 21 kPa of O2. According to these results, it was evident that the entire cultivation of spinach from seeding to harvest could be carried out at one-fourth atmospheric pressure when the O2 and CO2 partial pressures are at atmospheric levels.

Method for purification of gas streams by removal of acidic gases

Abstract: A method and apparatus for removal of acidic gases from a gas stream by contacting the gas stream with an amine vapor in a reaction zone. The partial pressure of amine vapor in the reaction zone is at least 5 percent of the total pressure therein, resulting in removal of at least 99 percent of the acidic gases. When operating at ambient temperature and substantially atmospheric pressure, preferred amines are methylamine and dimethylamine.