Download or read book Dynamics of Rotors on Refrigerant Lubricated Gas Foil Bearings written by Leister, Tim and published by KIT Scientific Publishing. This book was released on 2021-10-28 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The gas foil bearing (GFB) technology is a key factor for the transition to oil-free rotating machinery. Among numerous advantages, GFBs offer the unique ability to be lubricated with working fluids such as refrigerants. However, the computational analysis of refrigerant-lubricated GFB–rotor systems represents an interdisciplinary problem of enormous complexity. This work pushes forward existing limits of feasibility and establishes a new strategy that enables stability and bifurcation analyses.

Download or read book Refrigerant lubricated Gas Foil Bearings written by Mathieu Garcia and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Internal experiments at Liebherr-Aerospace FRANCE on new refrigerant-lubricated compressor designs have shown that under specific operating conditions, a mixture of vapor and liquid appears in the compressor, instead of a single-phase vapor flow. Therefore, refrigerant-lubricated foil bearings behavior is studied, including the likelihood of two-phase flow in the lubricant. We focus on the lubricant behavior only, in the operating conditions of foil bearings. The Thermo-Hydrodynamic approach describes lubricant characteristics such as pressure, density, viscosity, and temperature. It involves the use of a generalized Reynolds equation for turbulent flow, a nonlinear cubic equation of state for two-phase flow and a 3D turbulent thin-film energy equation. Journal bearing global parameters are calculated for steady-state conditions.

Download or read book Advances in Active Bearings in Rotating Machinery written by Athanasios Chasalevris and published by Springer Nature. This book was released on 2023-06-26 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports on cutting-edge experimental and numerical findings related to the application of active bearings, including smart ones, in rotating machinery. It discusses their role in improving stability and control of rotor systems and reports in depth on the corresponding modeling and control approaches. Chapters are based on peer-reviewed contributions to the 1st Workshop on Active Bearings in Rotating Machinery (ABROM 2022), held on June 29- 30, 2022, in Athens, Greece, and organized in collaboration between the School of Mechanical Engineering of The National Technical University of Athens (NTUA) and the Faculty of Mechanical Engineering of Karlsruhe Institute of Technology (KIT). In connection with the increasing digital transformation of machine elements, this book offers a timely perspective and extensive information on testing methods and experimental procedures involved in the development of intelligent rotors for industrial applications.

Download or read book On the Influence of Piecewise Defined Contact Geometries on Friction Dampers written by Aramendiz Fuentes, Jimmy Alberto and published by KIT Scientific Publishing. This book was released on 2023-09-12 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work considers dampers that do not solely focus on a single strategy but instead combine them. The capabilities of conventional dry friction dampers are expanded by taking into account piecewise defined contact geometries. This leads to friction dampers that change their behavior depending on the amplitude of the oscillations. The vibration damping device in this work, introduces damping at high oscillation amplitudes and takes advantage of absorption at low oscillation amplitudes.

Download or read book The Dynamics of Rotors in Gas Lubricated Bearings written by A. Tondl and published by . This book was released on 1968 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report explores self-excited vibration induced in rotors of gas lubricated bearings.

Download or read book Rotordynamics of Gas Lubricated Journal Bearing Systems written by Krzysztof Czolczynski and published by Springer. This book was released on 2012-09-24 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion of models for the behaviour of gas bearings, particularly of the aspects affecting the stability of the system. The text begins with a discussion of the mathematical models, identifying the stiffness and damping coefficients, and describing the behaviour of the models in unstable regions. It then turns to apply these results to bearings: static characteristics and stability of various rotor systems and an extensive discussion of air rings.

Download or read book Dynamic Behavior of Air Lubricated Pivoted pad Journal Bearing Rotor System written by Zolton N. Nemeth and published by . This book was released on 1970 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Behavior of Air Lubricated Pivoted pad Journal Bearing Rotor System Pivoted Consideration and pad mass written by Zolton N. Nemeth and published by . This book was released on 1972 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Investigation of Foil Bearings with Particular Emphasis on Gas Lubricated Films written by Ampex Corporation. Advanced Technology Division and published by . This book was released on 1970 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Foil Bearings for Axial and Radial Support of High Speed Rotors written by L. Licht and published by . This book was released on 1978 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flexible-surface thrust and journal foil-bearings of novel design were fabricated, and their performance was convincingly demonstrated, both individually and jointly as a unified rotor-support system. A versatile rig was constructed and instrumented, and experimental results are copiously documented with graphs and oscilloscopic data of trajectories, waveforms, and scans of amplitude response. The thrust bearings combine advantages of surface compliance with the superior load capacity of the spiral-groove configuration. The flexible supports provide means of deliberate control of clearance topography, in contrast to bearings in which the formation of the lubricating wedge is casual and incidental. At speeds of 40,000 to 45,000 rpm and a mean clearance of the order of 15 to 20 micrometers (600 to 800 micro in.), the resilient, air-lubricated, spiral-groove thrust bearings comfortably 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). The construction of journal foil-bearings is extremely simple. In one design, a coiled ribbon of plane foil and a retaining cartridge constitute the only components. In another design, the plane foil is integral with a section preformed to an open octagon with rounded vertices. A radical departure from operational characteristics of rigid gas bearings is achieved.

Download or read book Evaluation of a Gas lubricated Foil Bearing for Control of Gas Turbine Engine Rotor Critical Speeds written by Robert H. Badgley and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Foil Bearings for Axial and Radial Support of High Speed Rotors written by Lazar Licht and published by . This book was released on 1978 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dynamic Analysis of a Three foil Rotor Support System in Zero Gravity Environment written by A. Eshel and published by . This book was released on 1969 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic and static behavior of a gas lubricated bearing, consisting of stretched foil sectors, is analyzed. General equations describing the fluid film and valid for shaft excursions of the order of the clearance, are desrived on the basis of planar motion and negligible fluid inertia. The analysis is then specialized to the case of a bearing consisting of three equally spaced foil sectors. For the static equilibrium condition, tensions and gaps are calculated and graphs are presented. For the dynamic case, the basic equations are linearized, and equations for the in- and out-of-phase steady-state response to sinusoidal excitation are derived. This serves as an illustration of foil-bearing dynamic behavior as well as for stability investigation. For the case of zero radial load, the effects of speed, rotor radius, foil thickness, wrap angle and initial tension on the coefficients of damping and stiffness are graphically presented. Within the range of parameters investigated, the following distinct characteristics of the foil bearing were found. (Author).

Download or read book Rotordynamic Performance of a Rotor Supported on Bump type Foil Bearings Experiments and Predictions written by Dario Rubio Tabares and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas foil bearings (GFB) appear to satisfy most requirements for oil-free turbomachinery, i.e. relatively simple in construction, ensuring low drag friction and reliable high speed operation. However, GFBs have a limited load capacity and minimal amounts of damping. A test rig for the rotordynamic evaluation of gas foil bearings was constructed. A DC router motor, 25 krpm max speed, drives a 1.02 kg hollow rotor supported on two bump-type foil gas bearings (L = D = 38.10 mm). Measurements of the test rotor dynamic response were conducted for increasing mass imbalance conditions. Typical waterfalls of rotor coast down response from 25 krpm to rest evidence the onset and disappearance of severesubsynchronousmotions with whirl frequencies at ~50% of rotor speed, roughly coinciding with the (rigid mode) natural frequencies of the rotor-bearing system. The amplitudes of motion, synchronous and subsynchronous, increase (non) linearly with respect to the imbalance displacements. The rotor motions are rather large; yet, the foil bearings, by virtue of their inherent flexibility, prevented the catastrophic failure of the test rotor. Tests at the top shaft speed, 25 krpm, did not excite subsynchronous motions. In the experiments, the subsynchronous motion speed range is well confined to shaft speeds ranging from 22 krpm to 12 krpm. The experimental results show the severity of subsynchronous motions is related to the amount of imbalance in the rotor. Surprisingly enough, external air pressurization on one side of the foil bearings acted to reduce the amplitudes of motion while the rotor crossed its critical speeds. An air-film hovering effect may have enhanced the sliding of the bumps thus increasing the bearings' damping action. The tests also demonstrate that increasing the gas feed pressure ameliorates the amplitudes of subsynchronous motions due to the axial flow retarding the circumferential flow velocity development. A finite element rotordynamic analysis models the test rotor and uses predicted bearing force coefficients from the static equilibrium GFB load analysis. The rotordynamic analysis predicts critical speeds at ~8 krpm and ~9 krpm, which correlate well with test critical speeds. Predictions of rotordynamic stability are calculated for the test speed range (0 to 25 krpm), showing unstable operation for the rotor/bearing system starting at 12 krpm and higher. Predictions and experimental results show good agreement in terms of critical speed correlation, and moderate displacement amplitude discrepancies for some imbalance conditions. Post-test inspection of the rotor evidenced sustained wear at the locations in contact with the bearings' axial edges. However, the foil bearings are almost in pristine condition; except for top foil coating wear at the bearing edges and along the direction of applied static load.

Download or read book Design Guide for Gas lubricated Tilting pad Journal and Thrust Bearings with Special Reference to High speed Rotor written by Edgar J. Gunter and published by . This book was released on 1964 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement and Prediction of Nonlinear Dynamics of a Gas Foil Bearing Supported Rigid Rotor System written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rotor bearing Dynamics Technology Design Guide written by Coda H. T. Pan and published by . This book was released on 1980 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report reviews gas lubrication technology as applicable to the support of aero propulsion equipment. It contains a historical sketch of the evolution of the field, a review of relevant fundamentals, a discussion of the whirl stability phenomena, the design of thrust bearings for turbomachines, a brief report on the current state of materials development, and a general review of gas lubricated compliant bearings.