Air bearings are extensively used in precision machine design. Unlike conventional bearings, there is no physical contact between the moving surfaces. The moving surface can glide smoothly on the other surface, minimizing the control effort to achieve high accuracy and precision. Despite many advantages over conventional bearings, their application is still very limited. Cost and complexities in the design are the major deterrents. The orifice-type of air bearings are cheaper, but require good and innovative design to achieve better performance and stability in comparison to the porous-type. This book offers an analytical approach to understand the dynamics and the performance behavior of a single orifice, circular-pocketed air thrust bearing. The effect of various input parameters on the performance of the air bearing was studied. Based on the analytical results, a simple design methodology was developed to assist in the design and selection of air bearings. CFD simulation and experiments were carried out for validation purposes. An experimental set-up was designed to test static and dynamic performance characteristics of the air bearings.

Several types of air bearings are discussed and analyzed which can effectively simulate a frictionless environment for testing space vehicle instruments and control systems. A spherical dual-flow bearing, designed for a load of 15 pounds and employing an input pressure of about 4.5 psi, has been operated with an effective coefficient of friction of only 0.00000406. However, unless all externally applied torques as well as the center of gravity of the test fixture are exactly are the bearing's center of gravity of the test fixture are exactly at the bearing's center of rotation, it will precess. This is overcome in a cylindrical dual-flow bearing designed on the same principal. A spherical mono-flow bearing, which will bear loads of 700 and 400 pounds respectively with low input pressures, are also discussed. Plots of theoretical and actual performance are given, and fabrication techniques are described.

Comprehensive treatise on gas bearing theory, design and application This book treats the fundamental aspects of gas bearings of different configurations (thrust, radial, circular, conical) and operating principles (externally pressurized, self-acting, hybrid, squeeze), guiding the reader throughout the design process from theoretical modelling, design parameters, numerical formulation, through experimental characterisation and practical design and fabrication. The book devotes a substantial part to the dynamic stability issues (pneumatic hammering, sub-synchronous whirling, active dynamic compensation and control), treating them comprehensively from theoretical and experimental points of view. Key features: Systematic and thorough treatment of the topic. Summarizes relevant previous knowledge with extensive references. Includes numerical modelling and solutions useful for practical application. Thorough treatment of the gas-film dynamics problem including active control. Discusses high-speed bearings and applications. Air Bearings: Theory, Design and Applications is a useful reference for academics, researchers, instructors, and design engineers. The contents will help readers to formulate a gas-bearing problem correctly, set up the basic equations, solve them establishing the static and dynamic characteristics, utilise these to examine the scope of the design space of a given problem, and evaluate practical issues, be they in design, construction or testing.

New testing capabilities are needed in order to foster thrust foil air bearing technology development and aid its transition into future Oil-Free gas turbines. This paper describes a new test apparatus capable of testing thrust foil air bearings up to 100 mm in diameter at speeds to 80,000 rpm and temperatures to 650 C (1200 F). Measured parameters include bearing torque, load capacity, and bearing temperatures. This data will be used for design performance evaluations and for validation of foil bearing models. Preliminary test results demonstrate that the rig is capable of testing thrust foil air bearings under a wide range of conditions which are anticipated in future Oil-Free gas turbines. Torque as a function of speed and temperature corroborates results expected from rudimentary performance models. A number of bearings were intentionally failed with no resultant damage whatsoever to the test rig. Several test conditions (specific speeds and loads) revealed undesirable axial shaft vibrations which have been attributed to the magnetic bearing control system and are under study. Based upon these preliminary results, this test rig will be a valuable tool for thrust foil bearing research, parametric studies and technology development.Bauman, SteveGlenn Research CenterCALIBRATING; FOIL BEARINGS; GAS TURBINES; THRUST BEARINGS; TEST FACILITIES; MECHANICAL ENGINEERING; SHAFTS (MACHINE ELEMENTS); TORQUE; VIBRATION; LOADS (FORCES); AIR FLOW...

Solve your bearing design problems with step-by-step procedures and hard-won performance data from a leading expert and consultant Compiled for ease of use in practical design scenarios, Hydrostatic, Aerostatic and Hybrid Bearing Design provides the basic principles, design procedures and data you need to create the right bearing solution for your requirements. In this valuable reference and design companion, author and expert W. Brian Rowe shares the hard-won lessons and figures from a lifetime's research and consultancy experience. Coverage includes: - Clear explanation of background theory such as factors governing pressure, flow and forces, followed by worked examples that allow you to check your knowledge and understanding - Easy-to-follow design procedures that provide step-by-step blueprints for solving your own design problems - Information on a wide selection of bearing shapes, offering a range and depth of bearing coverage not found elsewhere - Critical data on optimum performance from load and film stiffness data to pressure ratio considerations - Operating safeguards you need to keep in mind to prevent hot-spots and cavitation effects, helping your bearing design to withstand the demands of its intended application Aimed at both experienced designers and those new to bearing design, Hydrostatic, Aerostatic and Hybrid Bearing Design provides engineers, tribologists and students with a one-stop source of inspiration, information and critical considerations for bearing design success. - Structured, easy to follow design procedures put theory into practice and provide step-by-step blueprints for solving your own design problems. - Covers a wide selection of bearing shapes, offering a range and depth of information on hydrostatic, hybrid and aerostatic bearings not found elsewhere. - Includes critical data on optimum performance, with design specifics from load and film stiffness data to pressure ratio considerations that are essential to make your design a success.