The study of the effect of different orbit paths and whirl ratios on the rotordynamic coefficients of a smooth eccentric annular seal, using Computational Fluid Dynamics (CFD) was performed. The flow was simulated for two different orbits - linear and circular for orbit speeds ranging from 0 to 1. This was done using the FLUENT CFD code with a time - dependent solver which allowed the use of dynamic meshing and User Defined Functions (UDFs). The effect of clearance was also studied by simulating the flow through an eccentric seal with one-tenth the clearance and comparing the results. It was seen that the flow field varies significantly with both the change in orbit and clearance and this in turn affects the forces and rotordynamic coefficients. The linear orbit showed major changes in terms of both the flow fields and the resulting forces. The velocities, pressure magnitudes and forces were much larger than the circular orbit. Another important finding was that the behavior of the flow for the smaller clearance is viscosity dominated compared to the inertia dominated flow seen for large clearances. The computation of rotordynamic coefficients for the circular orbits used Childs' theory and it was seen that for larger clearances the CFD predictions were not in agreement with the expected trends from this theory. The smaller clearance simulations, however, show force predictions from which the rotordynamic coefficients obtained match the theory.

No description available.

Thesis (doctoral)--Universität zu Köln, 1982. / Includes bibliographical references and index.

The reduction or elimination of leakage of hydraulic fluid from fluid power systems is considered a fundamental prerequisite for the expanded use of fluid power. There is also a need to reduce seal friction to both reduce energy dissipation and eliminate control problems. These seals are developed through empirical means at the present time, since the fundamental physics of seal operation has been unclear. This research develops numerical models for analyzing reciprocating hydraulic rod seals with various rod surfaces. These models consist of coupled fluid mechanics, contact mechanics and deformation analyses. Both flooded and starved lubrication boundary conditions are applied. For seals with a smooth rod and a plunge-ground rod, the model combines a 1-D finite volume Reynolds equation solver with a 2-D axisymmetric finite element deformation and static contact mechanics analyses, and a Greenwood-Williamson contact mechanics analysis with rod motion. Leakage and friction, along with sealing zone details with the plunge-ground rod are compared with those with the smooth rod. The influence of rod surface finish on seal performance is investigated and explained, under both flooded and starved conditions For seals with a micro-patterned rod, the model consists of finite volume Reynolds equation solver, finite element deformation and static contact mechanics analyses and a Greenwood-Williamson dynamic contact mechanics analysis. This model is able to handle rod surface pattern with 3-dimensional geometrics. Simulations with different micro-pattern geometries are performed to analyze the fundamental mechanism of surface pattern effects on seal operation. Again, both flooded and starved conditions are applied and the results for both cases are compared and analyzed.

Thesis (Ph.D.) - University of St Andrews, May 2007.

Thesis (doctoral)--Universität zu Köln, 1982. / Includes bibliographical references and index.

Thesis--Universität Wien. / Illustrations wanting? Photocopy. -- 31 cm. Bibliography: leaves a-h (4th numbered section).

Studies have been made on age determination, reproduction, growth and population structure in the harbour seal (Phoca vitulina richardi). They are based upon gross and histological examinations of reproductive tracts, growth measurements, and associated canine teeth of 42 prenatal and 319 postnatal specimens collected between 1964 and 1965. In postnatal seals cementum annulations were used as the criterion of age. Two annulations are deposited annually, a translucent "dense, inorganic" band during the winter and spring and an opaque "less dense, more organic" band during the summer and fall. Their formation may result from an internal rhythm. In southeastern Vancouver Island (southern British Columbia) parturition occurs primarily during July, lactation then lasts 6 weeks with ovulation shortly thereafter in September. Implantation is delayed for 2 to 2½ months and birth is about 230 days later. The male's main breeding season begins at least 4 months in advance of the female's but ends shortly after. Extensive clines in the timing of the reproductive cycle of both sexes are found in the Pacific and Atlantic Oceans. First ovulations occur at 2 to 5 years of age with peak periods at 2 and 3 years. About 88.9% of all adult females produce young each year. Males mature at 5 and 6 years of age. Prenatal males and females grow at similar rates. Postnatal males, however, grow slightly faster and larger being about 10% longer and 36% heavier at asymptotic sizes. Sex ratios are about 1 : 1 from implantation until males reach sexual maturity at 5 years, their mortality rate then increases resulting in a gradually increasing percentage of females in older age groups. Males generally do not live longer than 20 years and females seldom more than 30 years. In a random kill sample the average annual sex ratio is 46.9% males, and 49.6% of all females and 33.7% of males are mature. From bounty return records and reproductive and population data a minimum population estimate of 75,000 seals is made for British Columbia. This is a density of about 4.4 seals per mile of coastline. / Science, Faculty of / Zoology, Department of / Graduate

鮑慕貞. / "2005年8月". / 論文(藝術碩士)--香港中文大學, 2005. / 參考文獻(leaves 1-2, 2nd group). / "2005 nian 8 yue". / Abstracts in Chinese and English. / Bao Muzhen. / Lun wen (yi shu shuo shi)--Xianggang Zhong wen da xue, 2005. / Can kao wen xian (leaves 1-2, 2nd group). / 論文部份 / Chapter 第一章： --- 槪論 / Chapter (一) --- 硏究肖形印的意義 --- p.1 / Chapter (二) --- 肖形印的分類 --- p.3 / Chapter (三) --- 肖形印的形製 --- p.5 / Chapter 第二章： --- 肖形印發展的問題 / Chapter (一) --- 復古主義與肖形印發展的關係 --- p.6 / Chapter (二) --- 正傳與非正傳的詮釋 --- p.9 / Chapter (三) --- 實用性的考慮 --- p.10 / Chapter 第三章： --- 當代肖形印的創作 / Chapter (一) --- 當代肖形印的形式和題材 --- p.11 / Chapter (二) --- 近現代肖形印篆刻家 --- p.12 / Chapter (三) --- 當代肖形印面對的衝擊 --- p.17 / Chapter (四) --- 肖形印創作的建議與望 --- p.20 / Chapter 第四章： --- 個人創作闡釋與反思 / Chapter (一) --- 創作媒介與題材的揀選 --- p.24 / Chapter (二) --- 對肖形印創作的學習 --- p.25 / 參考書目 --- p.1-2 / 圖版 --- p.1-5

Annular seals are devices, which are used in turboMachinery systems to reduce the flow leakage, and to provide better dynamic stability to the system. Leakage flow can strongly affect cooling quality, heating balance, and efficiency of a turboMachinery system. Due to the fact that annular seals can significantly reduce the flow leakage, and provide the most cost-effective way of enhancing the aerodynamic efficiency, understanding of the flow characteristics through the annular seal configurations is an important subject. Seals are classified in two main groups, which are contacting, and non-contacting seals. Straight annular and convergent seal configurations are characterized as non-contacting seals, and they are widely used in rotating turbocMachinery systems. The flow kinetic energy obtained from the flow pressure is dissipated by the effects of shear stresses along the free shear layers. In addition, viscosity of the flow has an impact on the dissipation rate of the flow kinetic energy. In this research, the leakage characteristics of the straight annular, and convergent seal configurations under specified working conditions are compared to each other. This study aims to investigate which seal configuration exhibits better leakage characteristics with respect to the different seal clearances, shaft speeds, surface roughness heights, and pressure ratios. Commercial code ANSYS Fluent is used to perform the flow simulations for the straight annular and convergent seal configurations. Effects of the seal clearances, shaft speeds, pressure ratios, and surface roughness heights on the leakage rate are analyzed. It was observed that the seal clearance has a significant impact on the flow leakage, and clearance control is an important subject in seal technology. Additionally, dynamic system is compared to the static system, and results showed that shaft speed less than 15,000 rpm has not considerable impacts on the leakage.