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Total pressure

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


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TL;DR: In this paper, a vaneless diffuser is measured with unsteady flow measuring instruments as well as with conventional instruments for steady flow, and the experimental results indicate that there are some flow phenomena which cannot be explained by the conception of mixing process, which can be explained quantitatively as the isentropic energy exchange between relative streamlines due to the circumferential pressure variation.
Abstract: There is controversy about the mechanism of decay of the asymmetric flow in the vaneless diffuser of centrifugal blowers. In order to clearly observe the behavior of asymmetric flow, every other flow passage of a centrifugal impeller is blocked with a punched plate so that a severely asymmetric flow is induced. The flow behavior in the vaneless diffuser is measured with unsteady flow measuring instruments as well as with conventional instruments for steady flow. The experimental results indicate that there are some flow phenomena which cannot be explained by the conception of mixing process. Such flow phenomena can be explained quantitatively as the isentropic energy exchange between relative streamlines due to the circumferential pressure variation. In addition, the wall roughness of the vaneless diffuser is changed, and the influence of the wall friction on the total pressure loss is compared with the predictions based on the two controversial hypothesis. While these data are handled, it is recognized that the time average total pressure is considerably larger than the mass average total pressure for a severely asymmetric flow. Therefore, if instruments for steady flow measurement are used near the impeller exit to measure the total pressure, the impeller efficiency may be overestimated and the diffuser efficiency may be underestimated.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the limitations on pressure and therefore depth of mineralization that may reasonably be derived from simple observations of the behavior of fluid inclusions (i.e., the existence of ice or CO 2 clathrate on the liquidus, the amount of expansion or contraction of the bubble as the host inclusion is crushed in oil on the microscope stage, and the freezing and homogenization temperatures for the inclusion).
Abstract: Pressure is the most important of the intensive parameters for relating epithermal mineralization to the geologic setting. This paper describes the limitations on pressure (and therefore depth) of mineralization that may reasonably be derived from simple observations of the behavior of fluid inclusions (i.e., the existence of ice or CO 2 clathrate on the liquidus, the amount of expansion or contraction of the bubble as the host inclusion is crushed in oil on the microscope stage, and the freezing and homogenization temperatures for the inclusion). It is based on the reasonable model that mineralization occurs from a hydrostatically pressured NaCl-CO 2 -H 2 O fluid, consistent with the probability that H 2 O and CO 2 are the only gases contributing significantly to the total pressure. The pressure of CO 2 is, of course, a function of CO 2 content, but, from 100 degrees to 300 degrees C, it is a surprisingly minor function of either temperature or salinity. The presence of the clathrate in freezing studies of fluid inclusions indicates pressures of CO 2 that add at least 1 km to the probable depth of inclusion trapping compared to that estimated from CO 2 -free water. Thus undetected (i.e., no clathrates on cooling) CO 2 in fluid inclusions can nonetheless contribute very significantly to the possible depth of epithermal mineralization. On the other hand, the observation that fluid inclusions crushed in oil have bubbles that do not expand (i.e., 2 ) at 25 degrees C), demonstrates CO 2 contents that could add at most a few tens of meters to the depth of mineralization.

29 citations

Journal ArticleDOI
TL;DR: In this paper, the output power of the 6328 A helium-neon gas laser has been investigated as a function of capillary diameter, total pressure, and He−Ne partial pressure ratio at optimum dc discharge currents.
Abstract: The output power of the 6328 A helium‐neon gas laser has been investigated as a function of capillary diameter, total pressure, and He‐Ne partial pressure ratio at optimum dc discharge currents. The optimum value of pTd (total pressure × capillary diameter) remains constant, and the scaling laws, power ∝ d, optimum current ∝ d are approximately satisfied for the four diameters investigated. The results suggest that optimum laser output is always achieved at the same value of electron mean energy and at a constant fractional ionization. This study permits a clearer understanding of the relationship between various helium‐neon discharge parameters and the 6328 A laser output power, and by extrapolation allows the prediction of optimum gas fill for other capillary diameters. These results should also be useful in analyzing the effect of gas cleanup on tube life.

29 citations

Journal ArticleDOI
01 Aug 2002-Carbon
TL;DR: In this article, the chemical kinetics of carbon fiber deposition using laser chemical vapor deposition (LCVD) was studied and the cause of volcano shaped deposits was also explored through experimentation and thermodynamic modeling, and found to be an etching reaction induced by the elevated temperatures at the center of the laser spot.

29 citations

Journal ArticleDOI
TL;DR: In this paper, a set of equations describing the dynamic behavior of fibrous aerosol filters is developed in analogy with that used in deep bed filtration of solid liquid suspensions, which involves two correction functions, fλ and fP, which account for the effect of deposited matter on the local rate of deposition and on local pressure gradient, respectively.

29 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202225
2021127
2020147
2019153
2018128