Farid Al-Bender

Air Bearings (eBook, PDF)

Theory, Design and Applications

• Format: PDF

Produktbeschreibung

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.

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Produktdetails

• Verlag: John Wiley & Sons
• Seitenzahl: 592
• Erscheinungstermin: 31. Dezember 2020
• Englisch
• ISBN-13: 9781118927236
• Artikelnr.: 60908177

Autorenporträt

Farid Al-Bender, Katholieke Universiteit Leuven, Belgium Dr. Ir. Farid Al-Bender is Hon. Professor in the Department of Mechanical Engineering at KU Leuven, where his main areas of research included air bearing design and fabrication, tribology, friction modelling and non-linear system dynamics. He is the Director of the consultancy bureau Air Bearing Precision Technology and founder of Leuven Air Bearings company (now LAB Motion systems) where he is a board member.

Inhaltsangabe

List of contributors

List of Tables

List of Figures

Preface

Nomenclature

1. Introduction

1.1 Gas lubrication in perspective

1.1.1 Short history

1.2 Capabilities and limitations of gas lubrication

1.3 When is the use of air bearings pertinent

1.4 Situation of the present work

1.5 Classification of air bearings for analysis purposes

1.6 Structure of the book 1

References

2 .General Formulation and Modelling

2.1 Introduction

2.1.1 Qualitative description of the flow

2.2 Basic equations of the flow

2.2.1 Continuity equation

2.2.2 Navier-Stokes momentum equation

2.2.3 The (thermodynamic) Energy equation

2.2.4 Equation of State

2.2.5 Auxiliary conditions

2.2.6 Comment on the solution of the flow problem

2.3 Simplification of the flow equations

2.3.1 Fluid properties and body forces

2.3.2 Truncation of the flow equations

2.3.3 Film flow (or channel flow)

2.4 Formulation of bearing flow and pressure models

2.4.1 The quasi-static flow model for axisymmetric EP bearing

2.4.2 The Reynolds plus restrictor model

2.5 The basic bearing characteristics

2.5.1 The load carrying capacity

2.5.2 The axial stiffness

2.5.3 The feed mass flow rate

2.5.4 The mass flow rate in the viscous region

2.5.5 The tangential resistive, "friction" force

2.6 Normalization and similitude

2.6.1 The axisymmetric flow problem

2.6.2 Geometry

2.6.3 Dimensionless parameters and similitude

2.6.4 The Reynolds equation

2.6.5 The bearing characteristics

2.6.6 Static similarity of two bearings

2.7 Methods of solution

2.7.1 Analytic methods

2.7.2 Semi-analytic Methods

2.7.3 Purely numerical methods

2.8 Summary

References

3. Flow into the bearing gap

3.1 Introduction

3.2 Entrance to a parallel channel (gap) with stationary, parallel walls

3.2.1 Analysis of flow development

3.3 Results and discussion

3.3.1 Limiting cases

3.3.2 Method of solution

3.3.3 Determination of the entrance length into a plane channel

3.4 The case of radial flow of a polytropically compressible fluid between nominally parallel plates

3.4.1 Conclusions on pressure-fed entrance

3.5 Narrow channel entrance by shear-induced flow

3.5.1 Stability of viscous laminar flow at the entrance

3.5.2 Development of the flow upstream of a slider bearing

3.5.3 Development of the flow downstream of the gap entrance

3.5.4 Method of solution

3.5.5 Conclusions regarding shear-induced entrance flow

3.6 Summary

References

4. Reynolds Equation: Derivation, forms and interpretations

4.1 Introduction

4.2 The Reynolds equation

4.3 The Reynolds Equation for various film/bearing arrangements and coordinate systems

4.3.1 Cartesian coordinates (x; y)

4.3.2 Plain polar coordinates (r; _)

4.3.3 Cylinderical coordinates (z; _) with constant R

4.3.4 Conical coordinates (r; _) (_ = _ = constant)

4.3.5 Spherical coordinates (_; _) (r = R = constant)

4.4 Interpretation of the Reynolds Equation when both surfaces are moving and not flat

4.4.1 Stationary inclined upper surface, sliding lower member

4.4.2 Pure surface motion

Rezensionen

All chapters are written in an authoritative yet easy-to-read manner. The introduction of similarity parameters and scale effects in different chapters and a nice blend of experimental comparisons to theoretical analyses sprinkled throughout will appeal to graduate students and researchers. In summary, this comprehensive book on air bearings is a carefully written, methodical, insightful, and welcome contribution to the tribology literature. --Michael Khonsari, Journal of Tribology, November 2021.

Air bearings are a technology originally developed by the computer industry and which over time has been adopted by precision machining and by very high speed rotating machines. The monographs dedicated to this subject can be counted on the fingers of one hand and the work of Farid Al Bender is an important and welcome contribution. This book gives at the same time solid theoretical bases, presents physical models, details their mathematical formulations and describes a large variety of technical solutions. The reader is delighted by the wealth of information grouped into 17 carefully chosen chapters. --Mihai Arghir, Tribology International, November 2021.