Total pressure

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

Transient characteristics of a centrifugal pump during stopping period

Abstract: A theoretical and experimental study has been made on the transient characteristics of a centrifugal pump during its rapid acceleration from standstill to final speed Instantaneous rotatinal speed, flow-rate, and total pressure rise are measured for various start-up schemes Theoretical calculations for the prediction of transient characteristics are developed and compared with the corresponding experimental results As the results of this study, it becomes clear that the impulsive pressure and the lag in circulation formation around impeller vanes play predominant roles for the difference between dynamic and quasi-steady characteristics of turbopump during its starting period

Self-healing mechanisms of a SiC fiber reinforced multi-layered ceramic matrix composite in high pressure steam environments

Abstract: Non-oxide ceramic matrix composites are potential candidates to replace the current nickel-based alloys for a variety of high temperature applications in the aerospace field. The durability of a SiC ( f ) /PyC ( i ) /[Si,C,B] ( m ) composite with a sequenced self-sealing matrix and Hi-Nicalon fibers was investigated at 600 °C for exposure durations up to 600 h. The specimens are aged in a variety of slow-flowing air/steam gas mixtures and total pressures, ranging from atmospheric pressure with a 10–50% water vapor content to 1 MPa with 10–20% water vapor content. The degradation of the composite was determined from the measurement of residual strength and strain to failure on post-exposure specimens and correlated with microstructural observations, weight changes and characterizations of the generated oxides. All of the post-exposure characterizations demonstrate the ability of the sequenced [Si,C,B] matrix to protect the PyC interphase from environmental attacks. Two different oxidation modes of the matrix, depending on the total pressure are discussed in terms of the reactivity of the boron-containing layers, and their relative positions in the sequenced matrix. In high pressure environments, a strong localized dissolving of a small amount of SiC fibers in the boria-containing oxide is evidenced at 600 °C.

Pressure-induced orientation control of the growth of epitaxial silicon nanowires.

Abstract: Single crystal silicon nanowires (SiNWs) were synthesized with silane reactant using Au nanocluster-catalyzed one-dimensional growth. We have shown that under our experimental conditions, SiNWs grown epitaxially on Si(111) via the vapor−liquid−solid growth mechanism change their growth direction as a function of the total pressure. Structural characterization of a large number of samples shows that SiNWs synthesized at a total pressure of 3 mbar grow preferentially in the ⟨111⟩ direction, while the one at 15 mbar favors the ⟨112⟩ direction. Specifically by dynamically changing the system pressure during the growth process morphological changes of the NW growth directions along their length have been demonstrated.

Fabrication of lotus-type porous stainless steel by continuous zone melting technique and mechanical property

Abstract: Lotus-type porous stainless steel (SUS304L) rods were fabricated by the continuous zone melting technique under a pressurized mixed gas of hydrogen and inert gas such as argon or helium. Pores with cylindrical shape, whose growth direction is parallel to the solidification direction, are observed in the rods. The dependence of the porosity and averaged pore diameter on the partial pressure of hydrogen or the total pressure and on the transference velocity of rods was investigated. It was found that the porosity increases with increasing partial pressure of hydrogen under a constant total pressure and the pore diameter decreases with increasing transference velocity. The maximum porosity was about 60 pct under the experimental conditions in the present work. The observation of the microstructure and the measurement of the tensile strength were also carried out.