scholarly journals Nonaxisymmetric Incompressible Hydrostatic Pressure Effects in Radial Face Seals

1978 ◽  
Vol 100 (3) ◽  
pp. 379-383 ◽  
Author(s):  
Izhak Etsion
Keyword(s):  
High Pressure ◽  
Axial Force ◽  
Dynamic Instability ◽  
Considerable Effect ◽  
Pressure Effects ◽  
Outer Diameter ◽  
Angular Misalignment ◽  
Outer Periphery ◽  
Inner Diameter ◽  
Flat Seal

A flat seal having an angular misalignment is analyzed, taking into account the radial variations in seal clearance. An analytical solution for axial force, tilting moment, and leakage is presented that covers the whole range from zero to full angular misalignment (surfaces in contact). It is shown that nonaxisymmetric hydrostatic pressures due to the radial variations in the film thickness have a considerable effect on seal stability. When the high pressure is on the outer periphery of the seal, both the axial force and the tilting moment are nonrestoring. This causes the seal surfaces to wear at the outer diameter. Instability and wear at the inner diameter can occur when angular misalignment is combined with radial distortions and the high pressure is on the inner periphery. The case of high-pressure seals, where cavitation is eliminated, is discussed, and the possibility of dynamic instability is pointed out.

scholarly journals Hydrodynamic Effects in a Misaligned Radial Face Seal

1979 ◽  
Vol 101 (3) ◽  
pp. 283-290 ◽  
Author(s):  
I. Etsion
Keyword(s):  
High Pressure ◽  
Analytical Solution ◽  
Strong Coupling ◽  
Axial Force ◽  
Cavitating Flow ◽  
Operating Mechanism ◽  
Face Seal ◽  
Angular Misalignment ◽  
Hydrodynamic Effects ◽  
Flat Seal

Hydrodynamic effects in a flat seal having an angular misalignment are analyzed, taking into account the radial variation in seal clearance. An analytical solution for axial force, restoring moment, and transverse moment is presented that covers the whole range from zero to full angular misalignment. Both low pressure seals with cavitating flow and high pressure seals with full fluid film are considered. Strong coupling is demonstrated between angular misalignment and transverse moment which leads the misalignment vector by 90 degrees. This transverse moment, which is entirely due to hydrodynamic effects, may be a significant factor in seal operating mechanism.

scholarly journals Morphological Changes in Lamellar Macular Holes According to SD-OCT Examination over a Long Observation Period

Diagnostics ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1145
Author(s):  
Magdalena Kal ◽  
Izabela Chojnowska-Ćwiąkała ◽  
Mateusz Winiarczyk ◽  
Monika Jasielska ◽  
Jerzy Mackiewicz
Keyword(s):  
Retinal Thickness ◽  
Morphological Changes ◽  
Outer Diameter ◽  
Corrected Visual Acuity ◽  
Macular Holes ◽  
Kolmogorov Smirnov ◽  
Inner Diameter ◽  
Observation Period ◽  
Sd Oct

Background: The aim of this study was to evaluate the quantitative morphological changes in lamellar macular holes (LMHs) based on SD-OCT examinations and to assess the correlations among minimal retinal thickness (MRT), reading vision (RV), and best corrected visual acuity (BCVA) over a 36-month follow-up period. Methods: A group of 40 patients (44 eyes) with LMH was evaluated, with an average age of 69.87 (SD = 10.14). The quantitative parameters monitored in the follow-up period (at 0, 3, 6, 12, 18, 24, 30, and 36 months) were tested for normality of distribution by Shapiro–Wilk and Kolmogorov–Smirnov tests. Results: The RV and BCVA values were stable, and no significant changes were found at any of the check-ups during the 36-month follow-up period (BCVA p = 0.435 and RV p = 0.0999). The analysis of individual quantitative LMH parameters during the 36-month follow-up period did not demonstrate statistically significant differences: MRT (p = 0.461), Max RT temporal (p = 0.051), Max RT nasal (p = 0.364), inner diameter (ID) (p = 0.089), and outer diameter (OD) (p = 0.985). Conclusions: The observations at 0, 6, 12, 18, 24, 30, and 36 months revealed moderate and significant correlations between RV and MRT. No significant correlation between BCVA and MRT was observed.

Influence of fully submerged permanent magnets in the evaluation of heat transfer and performance analysis of single slope glass solar still

2021 ◽  
pp. 095765092110310
Author(s):  
Ajay Kumar Kaviti ◽  
Akkala Siva Ram ◽  
Amit Kumar Thakur
Keyword(s):  
Heat Transfer ◽  
Permanent Magnets ◽  
Outer Diameter ◽  
Solar Still ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Inner Diameter ◽  
Evaporative Heat Transfer ◽  
And Performance ◽  
Depth Water

In this experimental study, permanent magnets with three different sizes (M-1: 32 mm inner diameter, 70 mm outer diameter and 15 mm thick, M-2: 25 mm inner diameter, 60 mm outer diameter and 10 mm thick, M-3: 22 mm inner diameter, 45 mm outer diameter and 9 mm thick) are fully submerged in the single-slope glass solar still. The performance of magnetic solar stills (MSS) with three different sizes at 2 cm depth water to ensure that magnets are fully submerged is compared with conventional solar still (CSS) at the location 17.3850°N, 78.4867°E. Tiwari model is adapted to calculate the heat transfer coefficients (HTC), internal and exergy efficiencies. MSS with M-1, M-2 and M-3 significantly enhanced the convective, radiative, and evaporative heat transfer rate for the 2 cm depth of water. This is due to the desired magnetic treatment of water, which reduces the surface tension and increases the hydrogen bonds. The MSS's total internal HTC, instantaneous efficiencies led CSS by 25.52%, 28.8%, respectively, with M-1. Having various magnetic fields due to different magnets sizes increases MSS's exergetic efficiency by 33.61% with M-1, 33.76% with M-2, and 42.25% with M-3. Cumulative yield output for MSS with M-1, M-2, and M-3 is 21.66%, 17.64%, 15.78% higher than CSS. The use of permanent magnets of different sizes in the MSS is a viable, economical and straight forward technique to enhance productivity.

High pressure effects on the multiplet structure of the emission spectrum of coronene in a n‐alkane matrix

1977 ◽  
Vol 66 (2) ◽  
pp. 875-876 ◽  
Author(s):  
M. Lamotte ◽  
S. Risemberg ◽  
A. M. Merle ◽  
J. Joussot‐Dubien
Keyword(s):  
High Pressure ◽  
Emission Spectrum ◽  
Pressure Effects ◽  
Multiplet Structure ◽  
High Pressure Effects

High Pressure effects on electrical resistivity and dielectric properties of nanocrystalline SnO2

2005 ◽  
Vol 66 (10) ◽  
pp. 1621-1627 ◽  
Author(s):  
P. Thangadurai ◽  
A. Chandra Bose ◽  
S. Ramasamy ◽  
R. Kesavamoorthy ◽  
T.R. Ravindran
Keyword(s):  
High Pressure ◽  
Electrical Resistivity ◽  
Dielectric Properties ◽  
Pressure Effects ◽  
High Pressure Effects

Self-Organized, Tubular Hybrid Vascular Tissue Composed of Vascular Cells and Collagen for Low-Pressure-Loaded Venous System

1995 ◽  
Vol 4 (6) ◽  
pp. 597-608 ◽  
Author(s):  
Jiro Hirai ◽  
Takehisa Matsuda
Keyword(s):  
Vascular Tissue ◽  
Venous System ◽  
Seeding Density ◽  
Outer Diameter ◽  
Type I ◽  
Dependent Manner ◽  
Mixed Solution ◽  
Vascular Cells ◽  
Collagen Concentration ◽  
Inner Diameter

A tubular, hierarchically structured hybrid vascular tissue composed of vascular cells and collagen was prepared. First, a cold mixed solution of bovine aortic smooth muscle cells (SMCs) and Type I collagen was poured into a tubular glass mold composed of a mandrel and a sheath (example of dimensions: inner diameter, 1.5 mm; outer diameter, 7 mm; length, 7 cm). Upon incubation at 37°C, an SMC-incorporated collagenous gel was formed. After the sheath was removed, the resulting fragile tissue, when cultured in medium, thinned in a time-dependent manner to form an opaque, dense tissue. Higher SMC seeding density and lower initial collagen concentration induced more rapid and prominent shrinkage of the tissue. Morphologic investigation showed that over time, bipolarly elongated SMCs and collagen fiber bundles became positioned around the mandrel. Both components became circumferentially oriented. When the mandrel was removed, a tubular hybrid medial tissue was formed. A hybrid vascular tissue with a hierarchical structure was constructed by seeding endothelial cells onto the inner surface of the hybrid medial tissue. Prepared tissues tolerated luminal pressures as great as 100 mmHg and mechanical stress applied during an anastomotic procedure. This method allowed us to prepare a tubular hybrid medial tissue of predetermined size (inner diameter, wail thickness, and length) by selecting appropriate mold design, initial collagen concentration, and SMC seeding density. Such hybrid vascular tissues may provide physiological functions when implanted into the venous system.

scholarly journals Crystal Growth and High-Pressure Effects of Bi-Based Superconducting Whiskers

ACS Omega ◽  
2021 ◽  
Author(s):  
Ryo Matsumoto ◽  
Sayaka Yamamoto ◽  
Yoshihiko Takano ◽  
Hiromi Tanaka
Keyword(s):  
High Pressure ◽  
Crystal Growth ◽  
Pressure Effects ◽  
High Pressure Effects

Interpretation of the high-pressure effects in the rare-earth orthoferrites

1975 ◽  
Vol 11 (7) ◽  
pp. 2705-2706 ◽  
Author(s):  
C. Boekema ◽  
F. van der Woude ◽  
G. A. Sawatzky
Keyword(s):  
High Pressure ◽  
Rare Earth ◽  
Pressure Effects ◽  
High Pressure Effects ◽  
The Rare Earth

Utilizing Novel Expandable Steel Packers to Overcome Multi-Stage Fracturing Completion Deployment Challenges in Horizontal Gas Wells

2021 ◽  
Author(s):  
Ebikebena M. Ombe ◽  
Ernesto G. Gomez ◽  
Aldia Syamsudhuha ◽  
Abdullah M. AlKwiter
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Cost Effective ◽  
Outer Diameter ◽  
Gas Wells ◽  
Multi Stage ◽  
High Pressure High Temperature ◽  
Zonal Isolation ◽  
Gas Bearing ◽  
Productive Time

Abstract This paper discusses the successful deployment of Multi-stage Fracturing (MSF) completions, composed of novel expandable steel packers, in high pressure, high temperature (HP/HT) horizontal gas wells. The 5-7/8" horizontal sections of these wells were drilled in high pressure, high temperature gas bearing formations. There were also washed-outs & high "dog-legs" along their wellbores, due to constant geo-steering required to keep the laterals within the hydrocarbon bearing zones. These factors introduced challenges to deploying the conventional MSF completion in these laterals. Due to the delicate nature of their packer elastomers and their susceptibility to degradation at high temperature, these conventional MSF completions could not be run in such hostile down-hole conditions without the risk of damage or getting stuck off-bottom. This paper describes the deployment of a novel expandable steel packer MSF completion in these tough down-hole conditions. These expandable steel packers could overcome the challenges mentioned above due to the following unique features: High temperature durability. Enhanced ruggedness which gave them the ability to be rotated & reciprocated during without risk of damage. Reduced packer outer diameter (OD) of 5.500" as compared to the 5.625" OD of conventional elastomer MSF packers. Enhanced flexibility which enabled them to be deployed in wellbores with high dog-leg severity (DLS). With the ability to rotate & reciprocate them while running-in-hole (RIH), coupled with their higher annular clearance & tolerance of high temperature, the expandable steel packers were key to overcoming the risk of damaging or getting stuck with the MSF completion while RIH. Also, due to the higher setting pressure of the expandable steel packers when compared to conventional elastomer packers, there was a reduced risk of prematurely setting the packers if high circulating pressure were encountered during deployment. Another notable advantage of these expandable packers is that they provided an optimization opportunity to reduce the number of packers required in the MSF completion. In a conventional MSF completion, two elastomer packers are usually required to ensure optimum zonal isolation between each MSF stage. However, due to their superior sealing capability, only one expandable steel packer is required to ensure good inter-stage isolation. This greatly reduces the number of packers required in the MSF completion, thereby reducing its stiffness & ultimately reducing the probability of getting stuck while RIH. The results of using these expandable steel packers is the successful deployment of the MSF completions in these harsh down-hole conditions, elimination of non-productive time associated with stuck or damaged MSF completion as well as the safe & cost-effective completion in these critical horizontal gas wells.

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