Study, fabrication and testing of a foil-bearing rotor support system

High speed foil bearing rotor support syste

Foil bearings for axial and radial support of high speed rotors: Design, development, and determination of operating characteristics

Flexible surface thrust and journal foil bearings were fabricated, and their performance was demonstrated, both individually and jointly as a unified rotor support system. Experimental results are documented with graphs and oscilloscopic data of trajectories, waveforms, and scans of amplitude response. At speeds of 40,000 to 45,000 rpm and a mean clearance of the order of 15 to 20 micrometers (600 to 800 micrometers, the resilient, air lubricated, spiral groove thrust bearings support a load of 127 N (29 lb; 13 kgf), equivalent to 3.0 N/sq cm (4.5 lb/sq in 0.31 kgf sq cm). Journal bearings with polygonal sections provided stable and highly damped supports at speeds up to 50,000 rpm

Air entrainment in web handling: To be avoided or mastered?

The presence of ambient air is of prime importance in various industrial processes involving web handling. This paper is an attempt to answer the following questions: how does air influence the quality of the final product? How is it possible to cope with such a situation?After a brief description of a few basic problems of fluid mechanics, namely: (i) the development of boundary layers on moving webs and (ii) the flow structure and pressure generation in wedges (i.e. corner flows ), several illustrative examples are presented.(1) When a flexible web passes over a spindle, a thin air layer is formed between the two surfaces. This is typically a foil bearing configuration, which is important to master in order to reduce wear reduction or to avoid any misfunction at the head-tape interface. A brief survey of the historical works on this topic will be given.(2) In wound roll models, the stress field generated in the roll depends on the winding conditions (i.e. geometry and processing parameters) and on the flexible media bulk properties (elasticity or viscoelasticity) and surface properties (topography). It is well known that there is a strong link between the roughness of a surface (resulting from microparticles added to the resin) and its behavior in terms of air entrainment and evacuation. A first attempt to study the complex mechanisms governing this link is proposed.(3j In high velocity coating flows which are present in numerous processes (magnetic tape manufacturing, paper industry, ... ) some air can be entrained between the solid substrate and the liquid layer being coated on it. After a qualitative description of the complex phenomena occurring in the vicinity of the three-phase junction, the amount of air likely to be entrained is evaluated on the basis of a theoretical model.As a conclusion, a few recommendations for practical applications will be tentatively drawn

PROGRESSIVE MICROSCOPIC DAMAGE AND THE DEVELOPMENT OF MACROSCOPIC FRACTURE IN POROUS SANDSTONES

The precursory phenomena associated with dilatancy have been extensively studied as a potential means of earthquake prediction. It is known that microstructural damage induced dilatancy precedes macroscopic failure of a rock. However, the quantitative relationship between microstructural damage and fault development is not clearly understood. To better understand the mechanics of brittle faulting of rock and the association of precursory phenomena with faulting, a detailed microstructural study was conducted on porous sandstone deformed to different post-failure stages at different strain rates. A lateral relaxation loading configuration was adopted in which a cylindrical sample is deformed under decreasing radial stresses while the axial load remains constant. This loading path was proven to successfully map out the brittle failure envelope. Compared to conventional triaxial deformation testing, the relaxation loading configuration greatly increases the stability of fault growth. A suite of samples were deformed and subsequently unloaded at different post-failure stages, before macroscopic faulting occurred. Progressive microstructural damage was investigated via quantitative characterization of crack damage indices, crack density, and changes in porosity. Ultimately, this research will lead to an improved comprehension of the relationship between microscopic damage and macroscopic fracture development, providing a better insight into the brittle failure process

12th International Conference on Vibrations in Rotating Machinery

Since 1976, the Vibrations in Rotating Machinery conferences have successfully brought industry and academia together to advance state-of-the-art research in dynamics of rotating machinery. 12th International Conference on Vibrations in Rotating Machinery contains contributions presented at the 12th edition of the conference, from industrial and academic experts from different countries. The book discusses the challenges in rotor-dynamics, rub, whirl, instability and more. The topics addressed include: - Active, smart vibration control - Rotor balancing, dynamics, and smart rotors - Bearings and seals - Noise vibration and harshness - Active and passive damping - Applications: wind turbines, steam turbines, gas turbines, compressors - Joints and couplings - Challenging performance boundaries of rotating machines - High power density machines - Electrical machines for aerospace - Management of extreme events - Active machines - Electric supercharging - Blades and bladed assemblies (forced response, flutter, mistuning) - Fault detection and condition monitoring - Rub, whirl and instability - Torsional vibration Providing the latest research and useful guidance, 12th International Conference on Vibrations in Rotating Machinery aims at those from industry or academia that are involved in transport, power, process, medical engineering, manufacturing or construction

Fixed insulation development program Final report

Improved Centaur fixed fuel tank insulatio

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Study of fuel systems for LH2-fueled subsonic transport aircraft, volume 1

Several engine concepts examined to determine a preferred design which most effectively exploits the characteristics of hydrogen fuel in aircraft tanks received major emphasis. Many candidate designs of tank structure and cryogenic insulation systems were evaluated. Designs of all major elements of the aircraft fuel system including pumps, lines, valves, regulators, and heat exchangers received attention. Selected designs of boost pumps to be mounted in the LH2 tanks, and of a high pressure pump to be mounted on the engine were defined. A final design of LH2-fueled transport aircraft was established which incorporates a preferred design of fuel system. That aircraft was then compared with a conventionally fueled counterpart designed to equivalent technology standards

Thermo-hydro-mechanical characterisation of London clay

Geothermal energy has been increasingly utilised in recent years to meet the sustainability targets of civil engineering structures. Ground Source Energy Systems (GSESs) that make use of low enthalpy geothermal energy have been shown to be efficient in providing low carbon heating and cooling to structures. To better understand the impact of the Ground Source Energy Systems on the surrounding ground, it is important to obtain high-quality laboratory testing data regarding the thermo-hydro-mechanical (THM) behaviour of soils. Three pieces of temperature-controlled testing equipment designed at the Imperial College Geotechnical Laboratory were used in this research. i) The existing isotropic apparatus was enhanced with the installation of a mid-height pore pressure probe, to enable accurate monitoring of pore water pressure changes at different locations of the soil specimen during multiple cycles of heating and cooling. ii) A new thermal triaxial apparatus with a double load-cell measuring system was developed to enable the shearing of soil specimens at both ambient and elevated temperatures. iii) A new oedometer apparatus with a thermal bath was developed for the measurement of compression properties of London clay under different temperature levels. Thermal and mechanical calibrations have been performed on the instrumentation and are presented in this thesis. Procedures of how the measured and calculated values are obtained and how the calibration curves are determined are explained. Trail tests with dummy samples and real soil tests have been performed to validate the calibration and to assess the calibration errors. Consistent protocols for thermal testing of clays are developed and documented here. Corrections are applied to the data where appropriate. The assumptions and expressions used for corrections are presented. The design of the equipment, thermal and mechanical calibrations, testing procedures and corrections for data processing presented in this thesis can be used as a reference to perform thermal testing on soils in the future. The effect of temperature on the behaviour of London clay has been investigated and presented. Some key aspects of the soil behaviour, including compression characteristics, preconsolidation pressure, volume change, strength, stiffness and pore water pressure, have been evaluated. Soil behaviour observed in this research have been compared with that from the same or other clays in published work. Results obtained in this research could be used to calibrate appropriate constitutive models, for example, the fully coupled thermal model in the Imperial College Finite Element Program (ICFEP).Open Acces