scholarly journals Influence of radial pressure gradients on solute exchange in stirred benthic chambers

1996 ◽  
Vol 141 ◽  
pp. 303-311 ◽  
Author(s):  
RN Glud ◽  
S Forster ◽  
M Huettel
Keyword(s):  
Radial Pressure ◽  
Pressure Gradients ◽  
Solute Exchange ◽  
Benthic Chambers

Radial Pressure Wave Behavior in Transient Laminar Pipe Flows Under Different Flow Perturbations

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Tong-Chuan Che ◽  
Huan-Feng Duan ◽  
Pedro J. Lee ◽  
Silvia Meniconi ◽  
Bin Pan ◽  
...  
Keyword(s):  
Radial Pressure ◽  
Research Area ◽  
Laminar Flows ◽  
Generation Mechanism ◽  
Detection Methods ◽  
Pressure Waves ◽  
Pressure Gradients ◽  
Transient Pressure ◽  
Pipe Flows ◽  
2D Model

The study of transient pressure waves in both low- and high-frequency domains has become a new research area to provide potentially high-resolution pipe fault detection methods. In previous research works, radial pressure waves were evidently observed after stopping the laminar pipe flows by valve closures, but the generation mechanism and components of these radial pressure waves are unclear. This paper intends to clarify this phenomenon. To this end, this study first addresses the inefficiencies of the current numerical scheme for the full two-dimensional (full-2D) water hammer model. The modified efficient full-2D model is then implemented into a practical reservoir-pipeline-valve (RPV) system, which is validated by the well-established analytical solutions. The generation mechanism and components of the radial pressure waves, caused by different flow perturbations from valve operations, in transient laminar flows are investigated systematically using this efficient full-2D model. The results indicate that nonuniform changes in the initial velocity profile form pressure gradients along the pipe radius. The existence of these radial pressure gradients is the driving force of the formation of radial flux and radial pressure waves. In addition, high radial modes can be excited, and the frequency of flow perturbations by valve oscillation can redistribute the energy entrapped in each high radial mode.

Der Druckaufbau in einem stationären, magnetfeldstabilisierten Heliumplasma hoher Dichte und Temperatur

1968 ◽  
Vol 23 (2) ◽  
pp. 251-263 ◽  
Author(s):  
P. H. Grassmann
Keyword(s):  
State Physics ◽  
Solid State ◽  
Electron Density ◽  
Discharge Current ◽  
Radial Pressure ◽  
Pressure Gradients ◽  
Arc Plasma ◽  
Solid State Physics ◽  
Thermomagnetic Effect ◽  
Pressure Profiles

The density and temperature in a stationary, magnetically stabilized He arc plasma are determined. The axial temperatures measured are between 200000°K and 400000°K, depending on the discharge current. The electron densities are found to be ne = 1.5 × 1016 cm-3, this value being constant over the arc radius. These measurements yield very steep radial pressure gradients and axial pressures of up to 1 atm. The pressure profiles are dealt with quantitatively. It is shown that the pressure build-up is governed essentially by a thermomagnetic effect familiar in solid state physics, namely the Nernst effect. The theory of this effect readily explains why the electron density is constant over the radius.

Axially Symmetric Laminar Free Mixing With Large Swirl

1962 ◽  
Vol 84 (4) ◽  
pp. 370-374 ◽  
Author(s):  
Martin H. Steiger ◽  
Martin H. Bloom
Keyword(s):  
Boundary Layer ◽  
Compressible Flow ◽  
Free Stream ◽  
A Priori ◽  
Radial Pressure ◽  
Pressure Gradients ◽  
Axially Symmetric ◽  
Axial Pressure ◽  
Integral Methods ◽  
Special Case

Viscous laminar axially symmetric free mixing with large swirl is investigated by a boundary-layer type of analysis with integral methods. Large swirl generates axial pressure gradients as well as large radial pressure gradients, and therefore alters the streamwise flow. Examples calculated for both incompressible and compressible flow show that the wake may be significantly lengthened by large swirl. However, this effect is shown to be diminished in the compressible case where higher free-stream Mach numbers lead to decreased densities, and to decreased centrifugal effects, decreased radial pressure gradients, and decreased axial pressure gradients. In the limiting special case of small or moderate swirl the results agree with those previously obtained by Steiger and Bloom [1] in analysis wherein the induced pressure gradients were neglected a priori.

Stress-Induced Radial Pressure Gradients in Liquid-Filled Multiple Concentric Cylinders

1977 ◽  
Vol 44 (2) ◽  
pp. 218-221 ◽  
Author(s):  
M. Munro ◽  
K. Piekarski
Keyword(s):  
Hydrostatic Pressure ◽  
Pressure Gradient ◽  
Experimental Model ◽  
Analytical Model ◽  
Axial Loading ◽  
Radial Pressure ◽  
Pressure Gradients ◽  
Hydraulic Oil ◽  
Concentric Cylinders ◽  
Good Agreement

The concept of liquid-filled multiple concentric cylinders under compressive axial loading is investigated. An analytical model to predict the hydrostatic pressures in the liquid regions is formulated. It is found that upon loading a radially decreasing pressure gradient in the liquid layers is produced. The values of hydrostatic pressure from an experimental model comprising aluminum cylinders filled with hydraulic oil show good agreement with those predicted by the analytical model.

Computation of structures of flames with recirculating flow and radial pressure gradients

1979 ◽  
Vol 34 ◽  
pp. 309-326 ◽  
Author(s):  
D.E. Jensen ◽  
D.B. Spalding ◽  
D.G. Tatchell ◽  
A.S. Wilson
Keyword(s):  
Radial Pressure ◽  
Pressure Gradients ◽  
Recirculating Flow

A Method for Calculating Labyrinth Seal Inlet Swirl Velocity

1990 ◽  
Vol 112 (3) ◽  
pp. 380-383 ◽  
Author(s):  
R. Gordon Kirk
Keyword(s):  
Dynamic Stiffness ◽  
Axial Flow ◽  
Radial Pressure ◽  
Labyrinth Seal ◽  
Pressure Gradients ◽  
Labyrinth Seals ◽  
Friction Factors ◽  
Swirl Velocity ◽  
Vortex Solution ◽  
Inlet Swirl

The results of numerous investigators have shown the importance of inlet swirl on the calculated dynamic stiffness and stability of labyrinth seals. These results have not included any calculation of inlet leakage of swirl as a function of complex disk geometry including the sealing conditions of the given seal. This paper outlines a method of calculating the inlet swirl at the entrance of the labyrinth seal by introducing a radial chamber which when added to the axial flow solution allows the prediction of the gas swirl as it flows radially from the stage tip along the disk face inward to the seal location. This solution is consistent with the leakage model for the seal and allows rapid evaluation of seal designs. For a centrifugal compressor, this added feature permits the designer to include the flow path from the impeller discharge, down the back of the disk or front of the cover, then into the shaft seal or eye packing, respectively. The solution includes the friction factors of both the disk and stationary wall with account for mass flow rate and calculation of radial pressure gradients by a free vortex solution. The results of various configurations are discussed and comparisons made to other published results of disk circumferential velocity swirl.

Numerical Design and Experimental Evaluation of an Aggressive S-Shaped Compressor Transition Duct With Bleed

2011 ◽  
Author(s):  
A. D. Walker ◽  
A. G. Barker ◽  
J. F. Carrotte
Keyword(s):  
Axial Compressor ◽  
Flow Distribution ◽  
Axial Direction ◽  
Radial Pressure ◽  
Pressure Gradients ◽  
Successful Operation ◽  
Novel Approach ◽  
Limited Degree ◽  
Inlet Conditions ◽  
System Length

The ability to design S-shaped ducts with high aerodynamic loading is advantageous from a performance and/or weight saving perspective. However, the radial pressure gradients required to turn the flow produce strong pressure gradients in the axial direction. This promotes the likelihood of flow separation from the inner casing as the loading is increased. The current paper presents a novel approach to accommodating the increased loading by bleeding an amount of air from the critical inner casing. The process through which the air is bled re-energizes the boundary layer sufficiently to enable it to remain attached despite the high duct loading. A bled duct is numerically developed and experimentally evaluated using a fully annular isothermal facility, with representative inlet conditions provided by a single stage axial compressor. The measurements indicate successful operation of this new design concept with a reduction in the overall system length, compared to a conventional design, of approximately 30% and a reduction in loss of approximately 20%. The data also demonstrate, to a limited degree, the ability to control the flow distribution at duct exit ultimately improving flow uniformity. Furthermore, the pressure of the bled flow is higher than at rotor exit where, in current engine architectures, flow is typically removed from the main gas path. In other words current engine bleed locations could be replaced by a bleed flow within the transition duct, and this flow is of sufficient pressure to meet the existing requirements associated with cooling, sealing and/or zone ventilation.

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