Vibration Analysis of Gas Turbine Rotors

Vibration Analysis of Gas Turbine Rotors PDF

Author: Srinivasa Rao Dokku

Publisher: GRIN Verlag

Published: 2018-09-20

Total Pages: 61

ISBN-13: 3668803234

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Master's Thesis from the year 2016 in the subject Engineering - Mechanical Engineering, , language: English, abstract: The purpose of this report is to determine the lateral and torsional dynamic characteristics of the complete system under synchronous conditions of excitation and response. A damped natural response study was made in order to investigate the combined effect of oil film stiffness and damping coefficients on system damping and stability characteristics at all damped natural resonance speeds. An unbalance response analysis is also performed to study the system sensitivity. This study was performed to investigate the lateral vibration characteristics of the subject system in order to avoid vibration problems that might interfere with the smooth and reliable operation of the system. Total system studies are important in that often the coupling effects of marrying driver and driven equipment result in resonant speeds that are not calculable when investigating the response of the separate components. Oil film stiffness and damping for all bearings must be properly considered in the system calculations along with the effective stiffness and damping of pedestal supports as required. The above effects are in the following calculation to ensure the proper calculation of resonant speeds.The following study concerns itself with the lateral analysis of gas turbine, load coupling, and 50 Hz/15.75Kva generator. This study reports the lateral natural frequencies and mode shapes calculated from the mass and stiffness distribution of the beam elements modeled using the DYROBES software. An unbalanced response analysis is also performed to study the system sensitivity. The significance of torsional vibration in high speed rotating machinery is well established. It is desirable to keep all torsional natural frequencies away from operating speed as well as twice the electrical frequency of the system. However, this is not always feasible and, therefore torsional criticals can be tolerated within these regions provided the response to excitation levels are low enough to keep the alternating shear stress within acceptable levels The following study concerns itself with the complete torsional analysis of gas turbine rotor including load coupling, gear box and 50Hz/15.75KVA generator rotor. This study reports the torsional natural frequencies, mode shapes and Campbell diagram by using transfer matrix method. The transient response shear stresses were also calculated for fault condition.

Turbomachine Blade Vibration

Turbomachine Blade Vibration PDF

Author: J. S. Rao

Publisher: New Age International

Published: 1991

Total Pages: 466

ISBN-13: 9788122403046

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Fatigue Failures Of Blades Is One Of The Most Vexing Problems Of Turbomachine Manufacturers, Ever Since The Steam Turbine Became The Main Stay For Power Generating Equipment And Gas Turbines Are Increasingly Used In The Air Transport. The Problem Is Very Complex, Involving The Excitation Due To Aerodynamic Stage Interaction; Damping Due To Material Deformation, Friction At Slip Surfaces And Aerodynamic Damping; Vibration Of An Asymmetric Aerofoil Tapered Along Its Length And Mounted On A Rotating Disc At A Stagger Angle. The Problem Is Also Governed By Heat Transfer Analysis And Thermal Stresses.His Book Deals With A Basic Understanding Of Free Vibratory Behaviour Of Turbine Blades- Free Standing, Packetted, And Bladed-Discs. The Analysis Is Based On Continuous And Discrete Models Using Energy Principles And Finite Element Techniques. A Clear Understanding Of The Interference Phenomenon In A Thin Cambered Airfoil Stage In Subsonic Flow Is Presented To Determine The Nonsteady Excitation Forces Acting On The Blades. A Comprehensive Treatment On The Blade Damping Phenomenon That Occurs In Turbines Is Given. The Nonlinear Damping Models Account For Material Damping And Friction Damping As A Function Of Rotational Speed For Each Mode. Resonant Response Calculation Procedures For The Steadily Running As Well As Accelerating Blades Are Given.Cumulative Damage Calculations Are Then Outlined For Fatigue Life Estimation Of Turbomachine Blades. The Book Also Deals With Heat Transfer Analysis And Thermal Stress Calculations Which Help In A Comprehensive Understanding Of The Blade Problems.

Turbine Engine Rotor Blade Damage Detection Through the Analysis of Vibration of Stationary Components

Turbine Engine Rotor Blade Damage Detection Through the Analysis of Vibration of Stationary Components PDF

Author: Jon Rylan Cox

Publisher:

Published: 2016

Total Pages: 226

ISBN-13:

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Rotor blade fault detection and health monitoring systems are crucial for gas turbine engine testing and evaluation. The most commonly used techniques involve monitoring blades directly using strain gages, or drilling optical access holes in the engine casing for non-contact probes to monitor blade deflection and vibration. In this work, less intrusive, indirect techniques for rotor blade fault detection are developed, based on the hypotheses that the vibratory response of stationary components excited by the rotor blade dynamic pressure pulse can be used to detect the presence, location, and severity of rotor blade damage and changes in rotor blade natural frequency. The vibratory responses of a stator probe and the fan casing are processed using two novel techniques and a modified version of an existing technique. The two novel techniques are vibratory peak arrival analysis, used to detect damage causing blade offset, and vibratory peak statistical analysis, used to detect damage causing increased non-integral vibration amplitude. The third technique, spectral sideband tracking analysis, uses an exact solution to a previously published indeterminate technique used to detect damage causing changes in blade natural frequency. Ultimately, the vibratory peak arrival analysis technique was successful in detecting the presence, location, and severity of an offset rotor blade using data from the stator probe. The vibratory peak statistical analysis technique results were less clear, most likely due to the presence of rotor imbalance and lack of blade non-integral vibration. The spectral sideband tracking technique can, in theory, detect changes in rotor blade natural frequency. However, in practice, the required spectral peaks do not rise above the noise present in the casing accelerometer data spectrum, again most likely due to the lack of rotor blade non-integral vibration. The major contributions to the state-of-the- art of rotor blade health monitoring include: 1) a successful method (vibratory peak arrival analysis) of determining the presence, location, and severity of damage causing blade offset using the vibratory response of a stationary component (stator probe), and 2) a solution to a previously published indeterminate equation to calculate rotor blade rotating natural frequency using the casing vibratory response.

Vibration of Continuous Systems

Vibration of Continuous Systems PDF

Author: Singiresu S. Rao

Publisher: John Wiley & Sons

Published: 2019-03-06

Total Pages: 816

ISBN-13: 1119424143

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A revised and up-to-date guide to advanced vibration analysis written by a noted expert The revised and updated second edition of Vibration of Continuous Systems offers a guide to all aspects of vibration of continuous systems including: derivation of equations of motion, exact and approximate solutions and computational aspects. The author—a noted expert in the field—reviews all possible types of continuous structural members and systems including strings, shafts, beams, membranes, plates, shells, three-dimensional bodies, and composite structural members. Designed to be a useful aid in the understanding of the vibration of continuous systems, the book contains exact analytical solutions, approximate analytical solutions, and numerical solutions. All the methods are presented in clear and simple terms and the second edition offers a more detailed explanation of the fundamentals and basic concepts. Vibration of Continuous Systems revised second edition: Contains new chapters on Vibration of three-dimensional solid bodies; Vibration of composite structures; and Numerical solution using the finite element method Reviews the fundamental concepts in clear and concise language Includes newly formatted content that is streamlined for effectiveness Offers many new illustrative examples and problems Presents answers to selected problems Written for professors, students of mechanics of vibration courses, and researchers, the revised second edition of Vibration of Continuous Systems offers an authoritative guide filled with illustrative examples of the theory, computational details, and applications of vibration of continuous systems.

Advances in Acoustics and Vibration

Advances in Acoustics and Vibration PDF

Author: Tahar Fakhfakh

Publisher: Springer

Published: 2016-09-01

Total Pages: 323

ISBN-13: 3319414593

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The book provides readers with a snapshot of recent research and industrial trends in field of industrial acoustics and vibration. Each chapter, accepted after a rigorous peer-review process, reports on a selected, original piece of work presented and discussed at International Conference on Acoustics and Vibration (ICAV2016), which was organized by the Tunisian Association of Industrial Acoustics and Vibration (ATAVI) and held March 21-23, in Hammamet, Tunisia. The contributions, mainly written by north African authors, covers advances in both theory and practice in a variety of subfields, such as: smart materials and structures; fluid-structure interaction; structural acoustics as well as computational vibro-acoustics and numerical methods. Further topics include: engines control, noise identification, robust design, flow-induced vibration and many others.This book provides a valuable resource for both academics and professionals dealing with diverse issues in applied mechanics. By combining advanced theories with industrial issues, it is expected to facilitate communication and collaboration between different groups of researchers and technology users.

Vibration Analysis of Gas Turbines by Intelligent Knowledge Base Systems

Vibration Analysis of Gas Turbines by Intelligent Knowledge Base Systems PDF

Author: Stephen P. King

Publisher:

Published: 1994

Total Pages:

ISBN-13:

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Market pressure within the aero industry, and the changing requirement of airline operators, motivates considerable effort to continuously improve the design of the modem day gas turbine. Fundamental to the development programme of a new gas turbine is the monitoring of vibrations of the engine during its development tests. This entails manual inspection and interpretation of thousands of diagrams depicting the vibration history observed by several hundred strain gauge transducers, located on rotating and stationary compressor blades. This thesis describes an Expert System, developed during a three year research contract (co-funded by Rolls-Royce and SERC), that has been devised to assist in the analysis task. Features, depicting various forms of vibration phenomena, are located on each diagram by image processing techniques and interpreted by stored engineering knowledge representing the experience of vibration engineers. Thus, the system is capable of scrutinising vibration data, obtained from engine tests, and classifying that data as acceptable or in need of further study. The thesis provides an overall description of the problem of vibration in gas turbines and describes the image processing techniques and methods of reasoning employed to interpret the data.

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