Influence of Pressure on Speed of Sound in Oil-Offloading Hoses

2021 ◽  
Author(s):  
Lennert Buijs ◽  
Irma Meijer ◽  
Hajo Pereboom ◽  
Stian Garlid ◽  
Knud Lunde
Keyword(s):  
Speed Of Sound ◽  
Static Pressure ◽  
Fluid Pressure ◽  
Water Hammer ◽  
Pressure Waves ◽  
Pressure Measurements ◽  
Applied Method ◽  
A Value ◽  
Pressure Surge ◽  
Sound Data

Abstract Pressure surge or water hammer simulations are performed to evaluate a safe design or operation of oil transfer systems. The speed of sound of the transferred fluid plays a key role within pressure surge simulations. Unlike for steel pipe systems, the speed of sound in hoses is not easily determined. In industry, a value of 450 m/s is frequently used for hoses, but this value is often used independent of conveyed fluid, pressure or the type of hose. For that reason, a project was performed that aimed to experimentally reaffirm existing speed of sound data and to extend its usable range by including tests at several static pressure levels. Speed of sound measurements were performed on two 20”, 12 meter long, water-filled oil offloading hoses. The speed of sound was determined by the initiation of pressure waves in the hoses, while performing pressure measurements on either side of the hose. These experiments were performed at different static pressures up to 18 bar(a). The measured values depend on the applied method to determine the speed of sound. For both applied methods, the speed of sound is higher than the classically assumed 450 m/s. The method that is considered best applicable for the purpose of the experiments, the speed of sound is significantly higher and can reach values up to 1100 m/s. The consequence of this is that the results from pressure surge studies in which 450 m/s was used, are not conservative.

Pressure-permeability relationships in basement membrane: effects of static and dynamic pressures

1998 ◽  
Vol 274 (4) ◽  
pp. H1327-H1334 ◽  
Author(s):  
Karel Klaentschi ◽  
J. Anne Brown ◽  
Philip G. Niblett ◽  
Angela C. Shore ◽  
John E. Tooke
Keyword(s):  
Basement Membrane ◽  
Membrane Permeability ◽  
Static Pressure ◽  
Pressure Waves ◽  
Fluid Flux ◽  
Filtration Barrier ◽  
A Value ◽  
Mean Pressure ◽  
Membrane Effects ◽  
Albumin Clearance

The glomerular basement membrane (GBM) is an important component of the filtration barrier that is the glomerular capillary wall. Previously GBM permeability has been investigated only under static pressures and often within a supraphysiological range. We used Matrigel as a model of GBM and formed membranes at the base of a filtration chamber. We measured membrane permeability under static and dynamic pressures. Matrigel membranes were size and charge selective toward neutrally and negatively charged dextrans. Their permeability (as measured by hydraulic conductivity) was found to decrease from 1.61 ± 0.06 to 0.75 ± 0.07 × 10−6cm ⋅ s−1 ⋅ cmH2O−1as static pressure increased from 6 to 78 cmH2O, an effect attributed to membrane compression. In comparison to static pressure, sinusoidal pressure waves with a mean pressure of 50 cmH2O decreased membrane permeability, e.g., fluid flux was reduced by a maximum of 2% to a value of 5.47 ± 0.38 × 10−5 cm/s; albumin clearance was reduced by a maximum of 5.2% to a value of 9.63 ± 1.06 × 10−6ml ⋅ cm−2 ⋅ s−1. Such changes were affected by the frequency of pressure wave application and could be attributed to a switching on and off of the membrane compression effect.

On the Optimum Utilization of Water Hammer

1988 ◽  
Vol 202 (4) ◽  
pp. 249-256 ◽  
Author(s):  
P H Azoury ◽  
M Baasiri ◽  
H Najm
Keyword(s):  
Water Hammer ◽  
Valve Closure ◽  
Pipe Length ◽  
A Value ◽  
Closure Time ◽  
Highly Sensitive ◽  
Pressure Surge ◽  
Comparison Of The Results ◽  
Optimum Water ◽  
Valve Area

The computerized method of characteristics was used to analyse, for a single pipeline discharging into the atmosphere, the effects of valve-closure schedule and pipe length on optimum water-hammer strength. It was found that the criteria of optimum water-hammer utilization are a non-linear inherent valve schedule in which the bulk of the pressure surge occurs near the beginning or towards the end of valve closure, together with as small a value of dimensionless valve-closure time and as high a value of wide-open valve area as is consistent with cavitation-free operation. Also, a comparison of the results with hydraulic ram test data suggests that optimum drive pipe length may be based solely on optimum water-hammer strength, in the light of the relative effects of pipe friction and dimensionless valve-closure time. In general, optimum pipe length is not highly sensitive to inherent valve-closure schedule, water-hammer strength, pipe size or reservoir head.

Digital manometry to measure cerebrospinal fluid pressure during lumbar puncture

2021 ◽  
pp. 197140092110551
Author(s):  
Robert Heider ◽  
Peter G Kranz ◽  
Erin Hope Weant ◽  
Linda Gray ◽  
Timothy J Amrhein
Keyword(s):  
Cerebrospinal Fluid ◽  
Lumbar Puncture ◽  
Pressure Measurement ◽  
Fluid Pressure ◽  
Cerebrospinal Fluid Pressure ◽  
Pressure Measurements ◽  
Csf Pressure ◽  
Left Lateral Decubitus Position ◽  
Significant Difference ◽  
Time Savings

Rationale and Objectives Accurate cerebrospinal fluid (CSF) pressure measurements are critical for diagnosis and treatment of pathologic processes involving the central nervous system. Measuring opening CSF pressure using an analog device takes several minutes, which can be burdensome in a busy practice. The purpose of this study was to compare accuracy of a digital pressure measurement device with analog manometry, the reference gold standard. Secondary purpose included an assessment of possible time savings. Materials and Methods This study was a retrospective, cross-sectional investigation of 71 patients who underwent image-guided lumbar puncture (LP) with opening CSF pressure measurement at a single institution from June 2019 to September 2019. Exclusion criteria were examinations without complete data for both the digital and analog measurements or without recorded needle gauge. All included LPs and CSF pressures were measured with the patient in the left lateral decubitus position, legs extended. Acquired data included (1) digital and analog CSF pressures and (2) time required to measure CSF pressure. Results A total of 56 procedures were analyzed in 55 patients. There was no significant difference in mean CSF pressures between devices: 22.5 cm H2O digitally vs 23.1 analog ( p = .7). Use of the digital manometer resulted in a time savings of 6 min (438 s analog vs 78 s digital, p < .001). Conclusion Cerebrospinal fluid pressure measurements obtained with digital manometry demonstrate comparable accuracy to the reference standard of analog manometry, with an average time savings of approximately 6 min per case.

Distortion reconstruction in S-ducts from wall static pressure measurements

2018 ◽  
Vol 28 (5) ◽  
pp. 1134-1155 ◽  
Author(s):  
Pierre Grenson ◽  
Eric Garnier
Keyword(s):  
Static Pressure ◽  
Active Flow Control ◽  
Hybrid Approach ◽  
Reconstruction Algorithm ◽  
Stochastic Estimation ◽  
Pressure Measurements ◽  
Reconstruction Algorithms ◽  
Detached Eddy Simulation ◽  
Flow Distortion ◽  
Content Type

Purpose This paper aims to report the attempts for predicting “on-the-fly” flow distortion in the engine entrance plane of a highly curved S-duct from wall static pressure measurements. Such a technology would be indispensable to trigger active flow control devices to mitigate the intense flow separations which occur in specific flight conditions. Design/methodology/approach Evaluation of different reconstruction algorithms is performed on the basis of data extracted from a Zonal Detached Eddy Simulation (ZDES) of a well-documented S-Duct (Garnier et al., AIAA J., 2015). Contrary to RANS methods, such a hybrid approach makes unsteady distortions available, which are necessary information for reconstruction algorithm assessment. Findings The best reconstruction accuracy is obtained with the artificial neural network (ANN) but the improvement compared to the classical linear stochastic estimation (LSE) is minor. The different inlet distortion coefficients are not reconstructed with the same accuracy. KA2 coefficient is finally identified as the more suited for activation of the control device. Originality/value LSE and its second-order variant (quadratic stochastic estimation [QSE]) are applied for reconstructing instantaneous stagnation pressure in the flow field. The potential improvement of an algorithm based on an ANN is also evaluated. The statistical link between the wall sensors and 40-Kulite rake sensors are carefully discussed and the accuracy of the reconstruction of the most used distortion coefficients (DC60, RDI, CDI and KA2) is quantified for each estimation technique.

A clinical comparison of subdural screw pressure measurements with ventricular pressure

1983 ◽  
Vol 58 (1) ◽  
pp. 45-50 ◽  
Author(s):  
A. David Mendelow ◽  
John O. Rowan ◽  
Lilian Murray ◽  
Audrey E. Kerr
Keyword(s):  
Head Injury ◽  
Intracranial Pressure ◽  
Severe Head Injury ◽  
Fluid Pressure ◽  
Ventricular Catheter ◽  
Pressure Measurements ◽  
Content Type ◽  
Single Lumen ◽  
Ventricular Fluid Pressure ◽  
Fine Print

✓ Simultaneous recordings of intracranial pressure (ICP) from a single-lumen subdural screw and a ventricular catheter were compared in 10 patients with severe head injury. Forty-one percent of the readings corresponded within the same 10 mm Hg ranges, while 13% of the screw pressure measurements were higher and 46% were lower than the associated ventricular catheter measurements. In 10 other patients, also with severe head injury, pressure measurements obtained with the Leeds-type screw were similarly compared with ventricular fluid pressure. Fifty-eight percent of the dual pressure readings corresponded, while 15% of the screw measurements were higher and 27% were lower than the ventricular fluid pressure, within 10-mm Hg ranges. It is concluded that subdural screws may give unreliable results, particularly by underestimating the occurrence of high ICP.

Static pressure measurements near an oblique shock wave

AIAA Journal ◽  
1971 ◽  
Vol 9 (2) ◽  
pp. 345-347 ◽  
Author(s):  
L. H. BACK ◽  
R. F. CUFFEL
Keyword(s):  
Shock Wave ◽  
Static Pressure ◽  
Oblique Shock ◽  
Oblique Shock Wave ◽  
Pressure Measurements

An experimental study of underexpanded sonic, coaxial, swirl jets

2004 ◽  
Vol 218 (1) ◽  
pp. 93-103 ◽  
Author(s):  
K-H Lee ◽  
T Setoguchi ◽  
S Matsuo ◽  
H-D Kim
Keyword(s):  
Static Pressure ◽  
Near Field ◽  
Flow Structures ◽  
Experimental Investigations ◽  
Pressure Measurements ◽  
Annular Nozzle ◽  
Free Jets ◽  
Underexpanded Jets ◽  
Secondary Stream ◽  
The Impact

The present study addresses experimental investigations of the near-field flow structures of an underexpanded sonic, dual, coaxial, swirl jet. The swirl stream is discharged from the secondary annular nozzle and the primary inner nozzle provides the underexpanded free jets. The interactions between the secondary swirl and primary underexpanded jets are quantified by a fine pitot impact and static pressure measurements and are visualized using a shadowgraph optical method. The pressure ratios of the secondary swirl and primary underexpanded jets are varied below 7.0. Experiments are conducted to investigate the effects of the secondary swirl stream on the primary underexpanded jets, compared with the secondary stream of no swirl. The results show that the presence of an annular swirl stream causes the Mach disc to move further downstream, with an increased diameter, and remarkably reduces the fluctuations of the impact pressures in the underexpanded sonic dual coaxial jet, compared with the case of the secondary annular stream with no swirl.

scholarly journals Fluid pressure waves trigger earthquakes

2015 ◽  
Vol 200 (3) ◽  
pp. 1279-1283 ◽  
Author(s):  
Francesco Mulargia ◽  
Andrea Bizzarri
Keyword(s):  
Oil And Gas ◽  
Nonlinear Partial Differential Equation ◽  
Active Faults ◽  
Fluid Pressure ◽  
Rock Joints ◽  
Pressure Waves ◽  
Earthquake Triggering ◽  
Oil And Gas Exploration ◽  
Exploration And Production ◽  
Von Mises

Abstract Fluids—essentially meteoric water—are present everywhere in the Earth's crust, occasionally also with pressures higher than hydrostatic due to the tectonic strain imposed on impermeable undrained layers, to the impoundment of artificial lakes or to the forced injections required by oil and gas exploration and production. Experimental evidence suggests that such fluids flow along preferred paths of high diffusivity, provided by rock joints and faults. Studying the coupled poroelastic problem, we find that such flow is ruled by a nonlinear partial differential equation amenable to a Barenblatt-type solution, implying that it takes place in form of solitary pressure waves propagating at a velocity which decreases with time as v ∝ t [1/(n − 1) − 1] with n ≳ 7. According to Tresca-Von Mises criterion, these waves appear to play a major role in earthquake triggering, being also capable to account for aftershock delay without any further assumption. The measure of stress and fluid pressure inside active faults may therefore provide direct information about fault potential instability.

Experimental Study of the Flow in the Suction Pipe of a Centrifugal Pump at Partial Flow Rates in Unsteady Conditions

1999 ◽  
Vol 121 (3) ◽  
pp. 291-295 ◽  
Author(s):  
S. Bolpaire ◽  
J. P. Barrand
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Static Pressure ◽  
Pressure Measurements ◽  
Flow Rates ◽  
Suction Pipe ◽  
Start Up ◽  
Test Loop ◽  
Fast Start ◽  
Operational Range

The operational range and the performances of pumps are limited by the occurrence of backflow and prerotation in the suction pipe as the flow rate is reduced. This paper presents the study of static pressure measurements and visualizations in the suction pipe, near the inlet of a centrifugal pump, at partial flow rates, in steady conditions, and during a fast start-up of the pump. The tests were carried out in water on the DERAP© test loop of the ENSAM Lille laboratory. Standard methods allowed to determine the recirculation critical flow rate. A visualization method showed that the axial extent of the recirculation and the prerotation with the flow rate is considerably reduced during a fast start-up compared to steady conditions.

Tilt and Interfacial Fluid Pressure Measurements of a Disk Sliding on a Polymeric Pad

2005 ◽  
Vol 127 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Sum Huan Ng ◽  
Len Borucki ◽  
C. Fred Higgs ◽  
Inho Yoon ◽  
Andre´s Osorno ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Reynolds Equation ◽  
Fluid Pressure ◽  
Leading Edge ◽  
Dominant Factor ◽  
Pressure Measurements ◽  
Capacitive Sensing ◽  
One Dimensional ◽  
Pressure Mapping ◽  
Pressure Region

Previous experimental work has shown that negative fluid pressure does develop at the disk/pad interface during chemical mechanical polishing. However, these studies dealt with one-dimensional measurement and modeling. To better understand the problem, two-dimensional pressure mapping is carried out. In addition, the orientation of the disk is measured with a capacitive sensing technique. Results reveal a large negative pressure region at the disk/pad interface that is skewed toward the leading edge of the disk. The disk is also found to be leaning down toward the leading edge and toward the center of the pad. A mixed-lubrication model based on the Reynolds equation and taking into account the disk orientation angles has been developed. Modeling and experimental results show similar trends, indicating the tilting of the disk as a dominant factor in causing the negative pressure phenomenon.

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