Total pressure

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

Components of Pore Water Pressure and their Engineering Significance

Abstract: Pore fluid pressures that develop within soil masses as a result of both mechanical and physico-chemical effects influence the magnitude of the intergranular or effective stresses. The intergranular stresses control, in many cases, soil behavior in shear and compression. The physical significance of pore water pressure in a cohesive soil is examined in terms of several components which combine to give the total pressure. An analysis of fluid pressures at various points within a soil mass based on a condition of no flow at equilibrium shows that changes in any one component of the total pressure from point to point are offset by changes in other components.

Parametric Optimization of Unsteady End Wall Blowing on a Highly Loaded Low-Pressure Turbine

Abstract: Efforts to reduce blade count and avoid boundary layer separation have led to lowpressure turbine airfoils with significant increases in loading as well as front-loaded pressure distributions. These features have been independently shown to increase losses within the secondary flow field at the end wall. Compound angle blowing from discrete jets on the blade suction surface near the end wall has been shown to be effective in reducing these increased losses and enabling the efficient use of highly loaded blade designs. In this study, experiments are performed on the front loaded L2F low-pressure turbine airfoil in a linear cascade. The required mass flow is reduced by decreasing the hole count from previous configurations and from the introduction of unsteady blowing. The effects of pulsing frequency and duty cycle are investigated using phase-locked stereo particle image velocimetry to demonstrate the large scale movement and hysteresis behavior of the passage vortex interacting with the pulsed jets. Total pressure loss contours at the cascade outlet demonstrate that the efficiency benefit is maintained with the use of unsteady forcing. [DOI: 10.1115/1.4026127]

Mass and energy analyses of substrate-incident ions in TiO2deposition by RF magnetron sputtering

Abstract: Mass-resolved measurements of substrate-incident ion (SII) current and ion kinetic energy distributions (IEDs) were carried out for TiO2 deposition by rf (13.56 MHz) magnetron sputtering. Substrate-incident ion current was mainly composed of Ar+, O2+ and O+. Several minor ions, such as Ti+,TiO+, ArO+ and Ar2+ were also detected. The dominant species of substrate-incident ion was O2+ at a total pressure higher than 20 mTorr, while Ar+ was dominant one at a total pressure of 2 mTorr with which rutile TiO2 grew on a non-heated substrate. Variations in IEDs for Ar+ and O2+ against total gas pressure, oxygen flow rate and applied rf power were presented. The energy with peak intensity in IED and the mean ion energy increased with both decreasing pressure and increasing rf power. Strong correlation between IEDs and the growth of crystallized TiO2 were observed. Finally we discussed the growth condition of rutile TiO2 films based on the results including the dc self-bias voltage.

The Behavior of Transverse Cylindrical and Forward Facing Total Pressure Probes in Transverse Total Pressure Gradients

Abstract: When a total pressure probe is used for measuring flows with transverse total pressure gradients, a displacement of the effective center of the probe toward the higher total pressure is sometimes observed. This paper gives the results of an investigation of the effect for certain transverse cylindrical and forward facing (or pitot type) total pressure probes. An estimate of the error is given for the transverse cylindrical type of probe, and the errors due to position of hole, depth of hole, and wall proximity with this type of probe are considered incidentally. A design of a probe of the forward facing type possessing negligible displacement error is suggested.