Download or read book Rotordynamic Enhancement by Utilizing the Controlled Hydrostatic Injection of Hybrid Air Foil Bearing written by Behzad Zamanian Yazdi and published by . This book was released on 2019 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Air foil bearings (AFBs) are introduced as promising bearings for oil-free turbomachinery applications. Air foil bearing (AFB) technology has made substantial advancement during the past decades and found its applications in various small turbo machinery. AFBs provide reliable operation at high speed and high temperature with negligible power loss. However, rotordynamic instability, friction and drag during the start/stop, and thermal management are still challenges for further application of the technology. Hybrid Air Foil Bearing (HAFB) technology utilizes the radial injection of externally pressurized air into the traditional hydrodynamic AFB's film thickness through orifices attached to the top foil. HAFB is one of the technology advancements to the conventional AFB. Previous studies on HAFBs demonstrate the enhancement in the load capacity at low speeds, reduction or elimination of the friction and wear during starts/stops, better heat dissipation capability, and enhancement in rotordynamic stability. This dissertation is dedicated to explore the benefit of the HAFB to enhance the rotordynamic stability by employing a controlled hydrostatic injection. Moreover, this dissertation investigates the effect of circumferential location of radial injection on therotordynamic performance of HAFB. Analytical and experimental evaluations of the rotordynamic performance of a rotor supported by two HAFBs with the controlled hydrostatic injection, which utilizes the injections at particular locations to control eccentricity and attitude angle are presented. To investigate the effect of circumferential location of orifices, parametric studies are conducted using three sets of single-pad HAFBs. The circumferential locations of orificesare different for each set. The presented simulation analyses consist of time-domain orbit simulation and frequency-domain modal analysis. The simulations in both time-domain orbit simulations and frequency-domain modal analyses indicate a substantial improvement of the rotorbearing performance. The simulation results were verified in a high speed test rig(maximum speed of 70,000 rpm). Both simulations and experiments clearly demonstrate the effectiveness of the controlled hydrostatic injection on improving the rotordynamic performance of AFB. Imbalance responses of rotor-HAFB were measured with various orifice locations and the results agree well with predictions. Comparison of the rotordynamic performance of HAFBs with different orifice configurations demonstrate substantial improvement in rotordynamic stability as well as enhancement in the stiffness and damping coefficients of HAFBs by choosing the best circumferential location for radial injection to control rotor eccentricity and attitude angle.

Download or read book Rotordynamic Performance of a Rotor Supported by Three Pad Hybrid Air Foil Bearings with Controlled Air Injection written by Sandesh Gudemane and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Air Foil Bearings have found their place in the commercial applications of turbo machinery. They are cleaner and more reliable at high speeds than their conventional counterparts (Rolling Element Bearings). Low drag friction and apparently no contact during the operation results in a better service life and superior rotor-dynamic performance of the air foil bearings (AFBs). With these advantages AFB has proved to be a suitable option for oil-free turbo-machinery. Further development in AFBs suggest that pressurizing these bearings externally results in remarkably better load carrying capacity, heat dissipation and a more stable rotor. These externally air pressurized bearings which operate under hydrodynamic pressure with a hydrostatic lift are called Hybrid Air foil Bearing (HAFB). One of the major rotordynamic problem encountered in high speed turbomachinery is the subsynchronous vibration. If left unchecked, the higher amplitudes of subsynchronous vibrations can cause some serious damage to the bearing as well as the turbomachine. A previous study by Kim, D and Varrey, M [1] on a rotor of 4.84 kg supported by a three pad HAFB demonstrated the effects of increased air feed on the subsynchronous vibrations. The tests suggested an increase in the onset speed of subsynchronous vibration with higher pressures but minimal changes were observed in the natural frequencies. The present work is to numerically investigate the feasibility of controlled air injection to stabilize the rotor at high speeds. The intention is to push the rotor to higher eccentricity by loading it in one direction with the help of controlled air injection. The numerical analysis is carried out by orbit simulation method on a three pad HAFB of diameter 49 mm to test the whirl instability. The orbit simulation result suggests a delay in the appearance of subsynchronous vibrations. Further, experiments are carried out on a similar arrangement with the same rotor-bearing parameters. The shaft is loaded at the witness of subsynchronous vibrations (instability) to validate the simulation results. In actual practice out of the three air injection lines, one of the air injection lines is blocked to allow shaft loading and to notice its effects on the subsynchronous vibrations. The results were favorable, the amplitudes of subsynchronous vibrations diminished instantly suggesting a stable rotor as expected.

Download or read book Imbalance Response for a Four Degree of Freedom Rigid Rotor Supported by Hybrid Three Pad Air Foil Bearing written by Prajwal Krishna Shetty and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Air foil bearings (AFB's) are widely used in small to midsized turbomachinery. They provide safer, cleaner and cheaper bearing operation. They are simple in construction, offer very low drag friction and have very high reliability at high speed operations. A major advantage of air foil bearings compared to conventional rigid surface bearings is their superior dynamic performance in rotor bearing systems. Since there is no contact between the rotor and bearing surface, the air foil bearings have a higher service life compared to rigid surface bearings. Hybrid AFB's operate under both hydrodynamic and hydrostatic condition. The present study is a continuation of the work on hybrid air foil bearings (HAFB) by Kim and Park, where they develop and present an AFB which operates in hydrodynamic condition in the presence of a hydrostatic lift. Their experiments proved that the HAFB's have greater rotor dynamic performance and load capacity compared to their hydrodynamic counterpart. They also showed that HAFB's have better heat dissipation capacity of the parasitic heat generated due to viscous drag of the rotor and due to conduction from various parts of the test rig, thereby enhancing their performance. Later Manish developed a model to determine the bearing stiffness and damping coefficient using linear perturbation method. He also presented detailed study on the dependence of stiffness and damping coefficients on various bearing design parameters like supply pressure, feed parameter, excitation frequency and bearing number This article presents the non linear imbalance response of a four degree of freedom (DOF) rigid rotor supported by two, three pad HAFB's. Generally, imbalance response of a rotor has been performed considering two degrees of freedom i.e. cylindrical mode of vibration. This assumption makes it hard to predict the response of rotor bearing system during failure mode of the bearing, since bearing failure occurs predominantly due to conical vibrations. The translational and gyroscopic motion of the rotor has been determined by solving non linear degrees of motion corresponding to the DOF's. Both hydrodynamic and hydrostatic conditions tests were performed using a custom made test rig. Imbalance response simulations were performed and compared with the empirical results.

Download or read book Hybrid Air Foil Bearing with External Pressurization written by Soongook Park and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Foil bearings are widely used for oil-free micro turbomachinery. One of the critical technical issues related to reliability of the foil bearings is a coating wear on the top foil and rotor during start/stops. Bearing cooling is also mandatory for certain applications because the foil bearings can generate significant amount of heat depending on operating conditions. Usually axial flow is used through the space between the top foil and bearing sleeve. In this thesis, a hybrid air foil bearing with external pressurization is introduced. The hybrid operation eliminates the coating wear during start-up/shut down, and also reduces drag torque during starts. Furthermore, this hybrid foil bearing does not need cooling system. An experimental test with a loaded bearing under hydrostatic mode demonstrates the high potential of hybrid air foil bearings. The load capacity of the hybrid foil bearing was measured at 20,000 rpm, and compared with that of hydrodynamic foil bearing. The hybrid foil bearing has much higher load capacity than the hydrodynamic foil bearing. The starting torque was also measured and compared with hydrodynamic bearing. A simple analytical model to calculate top foil deflection under hydrostatic pressurization has been developed. Predictions via orbit simulations indicate the hybrid air foil bearings can have a much higher critical speed and onset speed of instability than the hydrodynamic counter part. Major benefits of the hybrid foil bearings also include very low starting torque, reduced wear of the top foil and rotor, and very effective cooling capability by the pressurized air itself. This new concept of hybrid air foil bearings are expected to be widely applied to the oil free turbomachinery industry, especially for heavily loaded and/or high temperature applications.

Download or read book Rotordynamics of Turbomachinery written by John M. Vance and published by John Wiley & Sons. This book was released on 1991-01-16 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the rotordynamic considerations that are important to the successful design or troubleshooting of a turbomachine. Shows how bearing design, fluid seals, and rotor geometry affect rotordynamic behavior (vibration, shaft whirling, bearing loads, and critical speeds), and describes two successful computational methods for rotordynamic analysis in terms that can be understood by practicing engineers. Gives descriptive accounts of the state of the art in several areas of the field and presents important mathematical or computational concepts, describing equations and formulas in physical terms for better understanding. Also offers tips for troubleshooting unstable machines and provides practical interpretations of vibration measurements.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1993 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 934 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Tribology Handbook written by Michael J Neale and published by Elsevier. This book was released on 1995-12-15 with total page 577 pages. Available in PDF, EPUB and Kindle. Book excerpt: The renowned reference work is a practical guide to the selection and design of the components of machines and to their lubrication. It has been completely revised for this second edition by leading experts in the area.

Download or read book Performance and Durability of High Temperature Foil Air Bearings for Oil Free Turbomachinery written by C. DellaCorte and published by . This book was released on 2000 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance and durability of advanced, high temperature foil air bearings are evaluated under a wide range (10-50 kPa) of loads at temperatures from 25 to 650 deg C. The bearings are made from uncoated nickel based superalloy foils. The foil surface experiences sliding contact with the shaft during initial start/stop operation. To reduce friction and wear, the solid lubricant coating, PS 304, is applied to the shaft by plasma spraying. PS304 is a NiCr based Cr2O3 coating with silver and barium fluoride/calcium fluoride solid lubricant additions. The results show that the bearings provide lives well in excess of 30,000 cycles under all of the conditions tested. Several bearings exhibited lives in excess of 100,000 cycles. Wear is a linear function of the bearing load. The excellent performance measured in this study suggests that these bearings and the PS 304 coating are well suited for advanced high temperature, oil-free turbomachinery applications.

Download or read book Gas Turbine Engineering Handbook written by Meherwan P. Boyce and published by Elsevier. This book was released on 2017-09-01 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Gas Turbine Engineering Handbook has been the standard for engineers involved in the design, selection, and operation of gas turbines. This revision includes new case histories, the latest techniques, and new designs to comply with recently passed legislation. By keeping the book up to date with new, emerging topics, Boyce ensures that this book will remain the standard and most widely used book in this field. The new Third Edition of the Gas Turbine Engineering Hand Book updates the book to cover the new generation of Advanced gas Turbines. It examines the benefit and some of the major problems that have been encountered by these new turbines. The book keeps abreast of the environmental changes and the industries answer to these new regulations. A new chapter on case histories has been added to enable the engineer in the field to keep abreast of problems that are being encountered and the solutions that have resulted in solving them. Comprehensive treatment of Gas Turbines from Design to Operation and Maintenance. In depth treatment of Compressors with emphasis on surge, rotating stall, and choke; Combustors with emphasis on Dry Low NOx Combustors; and Turbines with emphasis on Metallurgy and new cooling schemes. An excellent introductory book for the student and field engineers A special maintenance section dealing with the advanced gas turbines, and special diagnostic charts have been provided that will enable the reader to troubleshoot problems he encounters in the field The third edition consists of many Case Histories of Gas Turbine problems. This should enable the field engineer to avoid some of these same generic problems

Download or read book Annual Research Progress Report written by and published by . This book was released on 1979 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Applied Mechanical Engineering written by Hari Kumar Voruganti and published by Springer Nature. This book was released on 2020-02-01 with total page 1161 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents select peer reviewed proceedings of the International Conference on Applied Mechanical Engineering Research (ICAMER 2019). The books examines various areas of mechanical engineering namely design, thermal, materials, manufacturing and industrial engineering covering topics like FEA, optimization, vibrations, condition monitoring, tribology, CFD, IC engines, turbo-machines, automobiles, manufacturing processes, machining, CAM, additive manufacturing, modelling and simulation of manufacturing processing, optimization of manufacturing processing, supply chain management, and operations management. In addition, recent studies on composite materials, materials characterization, fracture and fatigue, advanced materials, energy storage, green building, phase change materials and structural change monitoring are also covered. Given the contents, this book will be useful for students, researchers and professionals working in mechanical engineering and allied fields.

Download or read book Advances in Engineering Design written by Pawan Kumar Rakesh and published by Springer Nature. This book was released on 2021-02-04 with total page 557 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the selected peer-reviewed proceedings of the International Conference on Innovative Engineering Design (ICOIED 2020). The contents provide a multidisciplinary approach for the development of innovative product design and their benefits for the society. The book presents latest advances in various fields like design process, service development, micro/nano technology, sensors and MEMS, and sustainability in engineering design. This book can be useful for students, researchers, and professionals interested in innovative product/process design and development.

Download or read book Active Magnetic Bearings written by Gerhard Schweitzer and published by . This book was released on 1994 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbomachinery Rotordynamics written by Dara Childs and published by John Wiley & Sons. This book was released on 1993-04-16 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Imparts the theory and analysis regarding the dynamics of rotating machinery in order to design such rotating devices as turbines, jet engines, pumps and power-transmission shafts. Takes into account the forces acting upon machine structures, bearings and related components. Provides numerical techniques for analyzing and understanding rotor systems with examples of actual designs. Features an excellent treatment of numerical methods available to obtain computer solutions for authentic design problems.

Download or read book Modern Engineering for Design of Liquid Propellant Rocket Engines written by Dieter K. Huzel and published by AIAA. This book was released on 1992 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: