scholarly journals Analysis of Total Leakage Performance of Finger Seal Considering the Rough Seepage Effect

2020 ◽  
Vol 56 (3) ◽  
pp. 152
Author(s):  
ZHAO Hailin ◽  
CHEN Guoding ◽  
SU Hua
Keyword(s):  
Total Leakage

Sum-Rate Optimization Constrained by Consumed Power for Multi- Antenna Non-Regenerative Relay Network

2020 ◽  
Vol 10 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Maryam Alibeigi ◽  
Shahriar S. Moghaddam
Keyword(s):  
Relay Network ◽  
Minimization Algorithm ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Convex Problem ◽  
Semidefinite Programming Problem ◽  
Total Leakage ◽  
Sum Rate ◽  
Rate Optimization ◽  
Novel Algorithm

Background & Objective: This paper considers a multi-pair wireless network, which communicates peer-to-peer using some multi-antenna amplify-and-forward relays. Maximizing the throughput supposing that the total relay nodes’ power consumption is constrained, is the main objective of this investigation. We prove that finding the beamforming matrix is not a convex problem. Methods: Therefore, by using a semidefinite relaxation technique we find a semidefinite programming problem. Moreover, we propose a novel algorithm for maximizing the total signal to the total leakage ratio. Numerical analyses show the effectiveness of the proposed algorithm which offers higher throughput compared to the existing total leakage minimization algorithm, with much less complexity. Results and Conclusion: Furthermore, the effect of different parameters such as, the number of relays, the number of antennas in each relay, the number of transmitter/receiver pairs and uplink and downlink channel gains are investigated.

scholarly journals Wellbore trajectory control tool seal system leakage analysis based on steady gap flow

2020 ◽  
Vol 12 (6) ◽  
pp. 168781402093046 ◽  
Author(s):  
Lei Shi ◽  
Keqiang Wang ◽  
Ding Feng ◽  
Hong Zhang ◽  
Peng Wang
Keyword(s):  
Prediction Method ◽  
Electronic System ◽  
Contact Length ◽  
Trajectory Control ◽  
Analysis Model ◽  
Rotating Shaft ◽  
Element Analysis ◽  
Gap Flow ◽  
Total Leakage ◽  
Gap Height

Lubricant leakage will inevitably occur during the working process of wellbore trajectory control tools. Even including the lubricant compensation system, serious leakage will still cause lacks lubrication of the internal mechanical structure as well as electronic system damaged by external infiltration fluid, especially when it comes to battery sub and other electronic equipment. Seal system leakage prediction method was presented based on the assumption of steady gap flow. It is assumed that there is a constant gap between the lip seal and the rotating shaft, the gap height is determined by oil film thickness, and the length of the gap was determined by the contact analysis using the Mooney–Rivlin constitutive model. The analysis results show that the contact length between the primary seal lip and the rotary shaft is about 0.1 mm under the condition of ensuring the contact between the deputy seal lip and the rotary shaft. The overall lubricant leakage finite element analysis model was established, and the relationship between the internal lubricant pressure of the tool and the total leakage was obtained. The results of analysis indicate that under the internal pressure of 0.03 MPa, the lubricant leakage is approximately 6 mL/h, which was verified by experiments.

Antimicrobial mode of action of secretions from the metapleural gland ofMytmecia gulosa(Australian bull ant)

1995 ◽  
Vol 41 (2) ◽  
pp. 136-144 ◽  
Author(s):  
J. A. Mackintosh ◽  
J. E. Trimble ◽  
A. J. Beattie ◽  
D. A. Veal ◽  
M. K. Jones ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antimicrobial Agents ◽  
Structural Integrity ◽  
Phospholipid Bilayer ◽  
Active Components ◽  
Cytoplasmic Matrix ◽  
Metapleural Glands ◽  
Total Leakage ◽  
Membrane Bound ◽  
And Function

Secretions from exocrine metapleural glands of Myrmecia gulosa (Australian bull ant) exhibit broad-spectrum antimicrobial activity. Treatment of the yeast Candida albicans with metapleural secretion resulted in the rapid and total leakage of K+ions from cells within 10 min. Ultrastructural analysis of the bacteria Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa, and cells and protoplasts of Candida albicans demonstrated gross damage of the cell membrane and aggregation of the cytoplasmic matrix of treated cells. Degradation of membrane-bound organelles was also observed in Candida albicans. The antimicrobially active components of metapleural secretions were nonpolar and interacted with the phospholipid bilayer, causing damage to the structural integrity of liposomes and the release of carboxyfluorescein. The data suggest that the antimicrobial agents in metapleural secretion act primarily by disrupting the structure and function of the phospholipid bilayer of the cytoplasmic membrane.Key words: ant metapleural secretion, antimicrobial, Candida albicans, cytoplasmic membrane.

CFD Leakage Predictions of Unworn and Worn Labyrinth Seals With and Without Tooth Axial Offset

2017 ◽  
Author(s):  
Hasham H. Chougule ◽  
Alexander Mirzamoghadam
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Modeling ◽  
Steady State ◽  
Flow Field ◽  
Labyrinth Seals ◽  
Small Clearance ◽  
Total Leakage ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Deflection

The objective of this study is to develop a Computational Fluid Dynamics (CFD) based methodology for analyzing and predicting leakage of worn or rub-intended labyrinth seals during operation. The simulations include intended tooth axial offset and numerical modeling of the flow field. The purpose is to predict total leakage through the seal when an axial tooth offset is provided after the intended/unintended rub. Results indicate that as expected, the leakage for the in-line worn land case (i.e. tooth under rub) is higher compared to unworn. Furthermore, the intended rotor/teeth forward axial offset/shift with respect to the rubbed land reduces the seal leakage. The overall leakage of a rubbed seal with axial tooth offset is observed to be considerably reduced, and it can become even less than a small clearance seal designed not to rub. The reduced leakage during steady state is due to a targeted smaller running gap because of tooth offset under the intended/worn land groove shape, higher blockages, higher turbulence and flow deflection as compared to worn seal model without axial tooth offset.

Geometry and Leakage Aspects of Involute Rotors for the Roots Blower

1968 ◽  
Vol 183 (1) ◽  
pp. 707-724 ◽  
Author(s):  
J. B. Ritchie ◽  
J. Patterson
Keyword(s):  
Compressed Air ◽  
Operating Efficiency ◽  
Geometrical Design ◽  
Design Variables ◽  
Design Values ◽  
Total Leakage ◽  
Base Circle ◽  
Carry Over ◽  
Tip Radius ◽  
The Ideal

For maximum operating efficiency of Roots type blowers, the leakage of compressed air through clearance must be reduced to a minimum. At the same time it is desirable to keep the design as compact as possible. The following analysis endeavours to show, for involute rotors, the effect of the geometrical design variables, pressure angle, rotor tip radius, and base circle radius, on leakage and compactness. Firstly limits of permissible values of the geometrical design variables, to allow correct mating between rotors, are established. Within these limits, relative blower compactness and carry-over of compressed air back to the inlet tract is obtained for the ideal blower with no clearance between relative rotating parts. The analysis and results are expressed in dimensionless form independent of blower size, and results are compared with cycloid rotors. Leakage through blower clearances, in terms of the geometrical design variables, is then determined for a range of pressure ratios, and the dependence on blower size is examined. It is concluded that optimum design values cannot be obtained. A compromise solution between minimum total leakage and maximum compactness is necessary, depending on the operating requirements for a particular Roots blower.

scholarly journals Research on the total leakage rate leak detection technology of the large spacecraft

2018 ◽  
Vol 1074 ◽  
pp. 012031 ◽  
Author(s):  
Yong Wang ◽  
Qiang Zhang ◽  
Jian Wang ◽  
Zhen Li ◽  
Wei Sun ◽  
...  
Keyword(s):  
Leak Detection ◽  
Leakage Rate ◽  
Detection Technology ◽  
Total Leakage

The Quantification of Seal-Interface Leakage of an Elastomer Face Seal

2011 ◽  
Author(s):  
Nicholas G. Garafolo ◽  
Christopher C. Daniels
Keyword(s):  
Contact Pressure ◽  
Leak Rate ◽  
Ring Test ◽  
Algebraic Solution ◽  
Definitive Evidence ◽  
Gas Leak ◽  
Face Seals ◽  
Total Leakage ◽  
Ring Seal ◽  
Mating Conditions

Current gas leak rate prediction methods for elastomeric face seals rely heavily on the assumption that all leakage is permeation, rather than leakage across the seal interface [1–3]. To date, there has been no definitive evidence that this is indeed the case. It is essential to investigate the magnitude of interface leakage to facilitate the validation of the current compressible permeation model and to quantify the interfacial leakage for the design of future state-of-the-art face seals. To this end, a series of leak rate experiments is presented on a square-ring seal, manufactured from silicone elastomer S0383-70. The unique experimental design affords the ability to quantify both a metal-elastomer interface, as well as an elastomer-elastomer interface. The experiments utilized two square-ring test specimens, each with a common width but different in height. The test apparatus consisted of stainless steel platens, near-hermetic plumbing, programmable environmental chamber, and the required instrumentation. The initial data reduction was accomplished by the mass point leak rate technique; whereas mass was calculated through measurements of gas pressure, temperature, and volume and a regression analysis yielded the leak rate of the seal. A secondary reduction of the leak rates in the unique experimental configuration further distinguished the total leakage into permeation and interface leak components, accomplished through the algebraic solution of the design of experiments guided matrix. Results showed that, with modest contact pressure, permeation was the largest component of the total leakage. In addition, the interface leakage for the various seal mating conditions (i.e., seal-on-flange, seal-on-seal) was quantified for the contact pressure investigated. Contrary to previous conclusions, the interface leakages were found to be significant. In the application of space docking seals, a common example of elastomeric face seals, the significance of quantifying the interfacial leakages guides the design of the seal for incomplete seal compression conditions as well has for the androgynous docking configuration.

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