Total pressure

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

Large-Eddy Simulation of Flow in a Low-Pressure Turbine Cascade

Abstract: Flow over three low-pressure turbine airfoils presented in [1] is analyzed for a range of Reynolds numbers (30,000 to 150,000) by means of large-eddy simulation. Baseline computational grid for these 2D linear cascade configurations consisted of 35 millions cells, and additional finer grids of 70 millions cells were used for grid sensitivity studies. For these low Reynolds number flows, this represents a quasi-DNS resolution which minimizes the role of the subgrid-scale model — however, WALE subgrid-scale model [7] was still employed. The configurations were analyzed for low free-stream turbulence intensity, as well as for 4% turbulence intensity at free-stream.Laminar separation exists on the suction side, and, depending on the Reynolds number, the flow at the outer edge of the separation either transitions, and the separation closes before the trailing edge, or not. Detailed comparisons to measurements are presented for computed surface pressure and total pressure losses over the range of Reynolds numbers for all three airfoils; these show that LES analyses are able to capture the main trends across all three geometries.Copyright © 2012 by United Technologies Corporation

Capacity factors in the performance of perforated plate columns

Abstract: A study was made of factors affecting the vapor-handling capacity of perforated-plate liquid-vapor contacting columns. Vapor-phase pressure drop across plates, liquid entrainment upward from plate to plate, and plate stability were investigated as functions of operational and geometric column parameters. Gas-phase pressure drop across dry perforated plates was observed to follow functional relationships predicted from available information for single perforations. The presence of liquid on a plate increased the total pressure drop by the equivalent clear-liquid head plus a small residue which is nearly constant for a given liquid. Entrainment was observed to be a function of column gas velocity, independent of gas velocity in the perforations. Weight rate of entrainment was also found to be proportional to the gas density, independent of liquid density, and inversely proportional to the liquid-surface tension. For a given system, entrainment was observed to be proportional to approximately the third power of the group, gas velocity divided by the distance between the liquid surface and the plate above. The stability of perforated plates was observed to be adequate for many industrial and experimental applications, as also reported in recently published studies, but contrary to qualitative statements found in the earlier literature. Stability was found to increase with decreasing perforation diameter and decreasing total perforation area relative to column cross-sectional area; to increase with greater gas density, liquid surface tension, and liquid wetting power; and to be virtually independent of liquid density and viscosity. Operating limits of vapor and liquid throughput are shown for a typical application of perforated plates in liquid-vapor contacting columns.

Flow Network Model based on Power Balance as Applied to Cross-Ventilation

Abstract: This paper reviews the flow network model based on power balance as applied to wind-induced cross ventilation in a residential building. The characteristics of wind-induced cross-ventilation with open windows in buildings are different from those of air infiltration through cracks in walls. The features of the velocity and pressure distributions are apparently different. In cross-ventilation, it seems that a kind of stream tube is formed through the building. A large part of the dynamic pressure generated at the opening is preserved within the room, and a major part of the preserved energy is directly convected outside the room. The preservation of energy is reflected as a decrease in the value of the total pressure loss coefficient, ζ. The static pressure loss does not express the total pressure loss through an opening. The flows in the building usually converge and diverge and thereby lose energy. The lost energy should also be accurately evaluated as in the total pressure loss coefficient, ζ, i...

Pressure drop for the flow of high concentration solid-liquid mixture across 90º horizontal conventional circular pipe bend

Abstract: Pressure drop across a 90° horizontal bend for fly ash slurry at high concentrations is reported in the present study. The pressure drop across the bend has been measured at five concentrations in the range of 50-65% (by weight) and the data has been analyzed to obtain the relative pressure drop, bend loss coefficient and permanent pressure loss. Measurements show that the relative pressure drop across the pipe bends increases with increase in concentration at low velocity. However, at any given concentration relative pressure drop is independent of velocity over the range tested. The bend loss coefficient at any velocity increases with increase in concentration. The permanent pressure loss increases marginally with concentration and velocity. The contribution of disturbed flow conditions downstream of the bend to the total pressure loss is much less in the case of highly concentrated slurries as compared to that in water.