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The Application Of Eulerian Laser Doppler Vibrometry To The On Line Condition Monitoring Of Axial Flow Turbomachinery Blades
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Book Synopsis The Application of Eulerian Laser Doppler Vibrometry to the On-line Condition Monitoring of Axial-flow Turbomachinery Blades by : Abraham Johannes Oberholster
Download or read book The Application of Eulerian Laser Doppler Vibrometry to the On-line Condition Monitoring of Axial-flow Turbomachinery Blades written by Abraham Johannes Oberholster and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The on-line condition monitoring of turbomachinery blades is of utmost importance to ensure the long term health and availability of such machines and as such has been an area of study since the late 1960s. As a result a number of on-line blade vibration measurement techniques are available, each with its own associated advantages and shortcomings. In general, on-blade sensor measurement techniques suffer from sensor lifespan, whereas non-contact techniques usually have measurement bandwidth limitations. One non-contact measurement technique that yields improvements in the area of measurement bandwidth is laser Doppler vibrometry. This thesis presents results and findings from utilizing laser Doppler vibrometry in an Eulerian fashion (i.e. a fixed reference frame) to measure on-line blade vibrations in axial-flow turbomachinery. With this measurement approach, the laser beam is focussed at a fixed point in space and measurements are available for the periods during which each blade sweeps through the beam. The characteristics of the measurement technique are studied analytically with an Euler-Bernoulli cantilever beam and experimental verification is performed. An approach for the numerical simulation of the measurement technique is then presented. Associated with the presented measurement technique are the short periods during which each blade is exposed to the laser beam. This characteristic yields traditional frequency domain signal processing techniques unsuitable for providing useful blade health indicators. To obtain frequency domain information from such short signals, it is necessary to employ non-standard signal processing techniques such as non-harmonic Fourier analysis. Results from experimental testing on a single-blade test rotor at a single rotor speed are presented in the form of phase angle trends obtained with non-harmonic Fourier analysis. Considering the maximum of absolute unwrapped phase angle trends around various reference frequencies, good indicators of blade health deterioration were obtained. These indicators were verified numerically. To extend the application of this condition monitoring approach, measurements were repeated on a five-blade test rotor at four different rotor speeds. Various damage cases were considered as well as different ELDV measurement positions. Using statistical parameters of the abovementioned indicators as well as time domain parameters, it is shown that with this condition monitoring approach, blade damage can successfully be identified and quantified with the aid of artificial neural networks.
Book Synopsis Condition Monitoring Using Computational Intelligence Methods by : Tshilidzi Marwala
Download or read book Condition Monitoring Using Computational Intelligence Methods written by Tshilidzi Marwala and published by Springer Science & Business Media. This book was released on 2012-01-25 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Condition Monitoring Using Computational Intelligence Methods promotes the various approaches gathered under the umbrella of computational intelligence to show how condition monitoring can be used to avoid equipment failures and lengthen its useful life, minimize downtime and reduce maintenance costs. The text introduces various signal-processing and pre-processing techniques, wavelets and principal component analysis, for example, together with their uses in condition monitoring and details the development of effective feature extraction techniques classified into frequency-, time-frequency- and time-domain analysis. Data generated by these techniques can then be used for condition classification employing tools such as: • fuzzy systems; rough and neuro-rough sets; neural and Bayesian networks;hidden Markov and Gaussian mixture models; and support vector machines.
Book Synopsis Evaluation of Optical Techniques Applied to Online Turbomachinery Blade Vibration Measurements by : Benjamin Gwashavanhu
Download or read book Evaluation of Optical Techniques Applied to Online Turbomachinery Blade Vibration Measurements written by Benjamin Gwashavanhu and published by . This book was released on 2015 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the dynamic characteristics of blades is important in the online condition monitoring of turbomachinery. Conventionally contact methods are used for this purpose. However improvements in technology now allow for the use of non-contact methods. Contact measurement techniques for turbomachinery blade vibration analysis typically involve the use of strain gauges and accelerometers. These present some complications when analyzing rotating machinery. Being contact in nature, mass loading can affect the integrity of measurements captured. Turbomachines typically operate under the adverse conditions of high temperatures, high flow rates and sometimes wet environments. This significantly reduces the life of contact transducers installed to capture the blade dynamics. Installation of telemetry systems for signal transmission is also necessary. In addition to being invasive and expensive, telemetry systems can introduce electrical noise. These factors make it desirable to explore the applicability of various optical non-contact methods for analyzing turbomachine blade vibrations, such as Laser Doppler Vibrometry (LDV) and photogrammetry. Both techniques have been successfully used to analyze vibrations of structures. Photogrammetry is a full-field measurement technique which allows for non-intrusive simultaneous measurement of vibrations at different locations on a blade. This is particularly important for the updating of numerically developed models of structures, investigation of structural global dynamics, and more effective localization of damage. Accelerometers have been used to validate a variation of photogrammetry, three dimensional point tracking (3DPT), for rotational applications and discrepancies attributed to the contact nature of accelerometers were observed. To build confidence in the use of 3DPT as a non-contact method for analyzing rotating machines, it is necessary to investigate how well it correlates with various non-contact methods.
Book Synopsis Laser Doppler Vibrometry by : Enrico Primo Tomasini
Download or read book Laser Doppler Vibrometry written by Enrico Primo Tomasini and published by Springer Nature. This book was released on 2020-06-29 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a continuous learning tool for experienced technical staff facing laser vibrometry technology for the first time. The book covers both theoretical aspects and practical applications of laser Doppler vibrometry, and is accompanied by a multimedia presentation that allows the audience to browse the content and come as close as possible to performing real experiments. After a brief introduction, Chapter 2 presents supporting theory, providing general information on light sources, light scattering and interference for a better understanding of the rest of the book. Chapter 3 examines the theory of laser vibrometers, explaining interferometers from an optical perspective and in terms of the related electronics. It also addresses options like tracking filters and different signal demodulation strategies, since these have a significant impact on the practical use of vibrometers. Chapter 4 explores the configurations that are encountered in today’s instrumentation, with a focus on providing practical suggestions on the use of laser vibrometers. Lastly, Chapter 5 investigates metrology for vibration and shock measurements using laser interferometry, and analyses the uncertainty of laser vibrometers in depth.
Book Synopsis Turbomachine Blade Vibration by : J. S. Rao
Download or read book Turbomachine Blade Vibration written by J. S. Rao and published by New Age International. This book was released on 1991 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Application of Laser Doppler Velocimeter to Chemical Vapor Laser System by : Luther R. Gartrell
Download or read book Application of Laser Doppler Velocimeter to Chemical Vapor Laser System written by Luther R. Gartrell and published by . This book was released on 1993 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analytical Investigation of Some Three-dimensional Flow Problems in Turbomachines by : Frank E. Marble
Download or read book Analytical Investigation of Some Three-dimensional Flow Problems in Turbomachines written by Frank E. Marble and published by . This book was released on 1952 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow of an incompressible inviscid fluid through a turbomachine with blade rows consisting of an infinite number of similar infinitely thin blades has been investigated theoretically in order to examine and describe the three-dimensional flow phenomena and to illustrate the methods of calculation developed.
Book Synopsis Transonic Flow Problems in Turbomachinery by : Thomas Charles Adamson
Download or read book Transonic Flow Problems in Turbomachinery written by Thomas Charles Adamson and published by . This book was released on 1977 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Vibration-based Condition Monitoring of a Turbomachinery Bladed System by : Anees ur Rehman
Download or read book Vibration-based Condition Monitoring of a Turbomachinery Bladed System written by Anees ur Rehman and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Static and rotating blades in turbine engines are susceptible to vibration-induced failure because of the high dynamic operating loads. Excitation can be broadband or linked to the rotation speed. The accurate functioning of the complete turbomachinery system depends on the structural integrity of individual blades as any propagating damage, in the form of a fatigue crack, intimidates the functioning of the entire system. Because of this, there is growing interest in the early detection of damage in blades. Damage detection in mistuned turbomachinery bladed systems is addressed in this research utilising a statistical approach to vibration-based damage detection. Initially, a modal characteristics-based damage identification technique is developed by obtaining damage indices based on the differences in the Modal Assurance Criterion (MAC) that give a measure of the change in the mode shapes. These damage indices are then correlated to the depth/location of the damage and also to the level/pattern of the mistuning present. The possibility of characterising cracks from their nonlinear response is investigated by detecting and classifying nonlinearity arising from a breathing crack interface. Nonlinearity detection is achieved by obtaining the amplitude dependent Frequency Response Functions (FRFs) and classification is accomplished by obtaining their Hilbert transform (HT). The breathing crack nonlinear behaviour is numerically validated by drawing a comparison between experimental and numerical results. The Coulomb friction-induced damping at the crack interface is quantified by obtaining relationships between crack depth/coefficient of friction and damping levels/friction stress/crack face pressures. Based on the conclusions from the breathing crack nonlinear behaviour investigations, damage detection in the mistuned bladed disc is addressed utilising outlier analysis. The effect of noise on the damage detection is studied by obtaining the maximum, mean and minimum damage detectability levels for varying noise. Both, the frequency and time domain data from the bladed disc are considered for damage detection. For the frequency domain, FRFs for varying mistuning levels in the bladed disc are obtained and damage detection is addressed when the FRF peak of the crack mode cannot be distinguished from the cluster of mistuning modes. In the time domain, the effectiveness of the developed damage detection procedure is examined for reduced data sets from the blade tips (blade tip timing).
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723025105 Total Pages :108 pages Book Rating :4.0/5 (251 download)
Book Synopsis Development of a Linearized Unsteady Euler Analysis for Turbomachinery Blade Rows by : National Aeronautics and Space Administration (NASA)
Download or read book Development of a Linearized Unsteady Euler Analysis for Turbomachinery Blade Rows written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: A linearized unsteady aerodynamic analysis for axial-flow turbomachinery blading is described in this report. The linearization is based on the Euler equations of fluid motion and is motivated by the need for an efficient aerodynamic analysis that can be used in predicting the aeroelastic and aeroacoustic responses of blade rows. The field equations and surface conditions required for inviscid, nonlinear and linearized, unsteady aerodynamic analyses of three-dimensional flow through a single, blade row operating within a cylindrical duct, are derived. An existing numerical algorithm for determining time-accurate solutions of the nonlinear unsteady flow problem is described, and a numerical model, based upon this nonlinear flow solver, is formulated for the first-harmonic linear unsteady problem. The linearized aerodynamic and numerical models have been implemented into a first-harmonic unsteady flow code, called LINFLUX. At present this code applies only to two-dimensional flows, but an extension to three-dimensions is planned as future work. The three-dimensional aerodynamic and numerical formulations are described in this report. Numerical results for two-dimensional unsteady cascade flows, excited by prescribed blade motions and prescribed aerodynamic disturbances at inlet and exit, are also provided to illustrate the present capabilities of the LINFLUX analysis. Verdon, Joseph M. and Montgomery, Matthew D. and Kousen, Kenneth A. Unspecified Center AXIAL FLOW; COMPUTATIONAL FLUID DYNAMICS; DIFFERENTIAL EQUATIONS; EULER EQUATIONS OF MOTION; INVISCID FLOW; LINEARIZATION; ROTOR BLADES (TURBOMACHINERY); SURFACE PROPERTIES; THREE DIMENSIONAL FLOW; UNSTEADY AERODYNAMICS; AEROACOUSTICS; AERODYNAMIC CONFIGURATIONS; AEROELASTICITY; AIR INTAKES; CASCADE FLOW; CYLINDRICAL BODIES; DUCTS; MATHEMATICAL MODELS; UNSTEADY FLOW...
Book Synopsis In-field Use of Laser Doppler Vibrometer on a Wind Turbine Blade by :
Download or read book In-field Use of Laser Doppler Vibrometer on a Wind Turbine Blade written by and published by . This book was released on 1998 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of our primary goals was to determine how well a laser Doppler vibrometer (LDV) could measure the structural dynamic response of a wind turbine that was parked in the field. We performed a series of preliminary tests in the lab to determine the basic limitations of the LDV for this application. We then instrumented an installed parked horizontal axis wind turbine with accelerometers to determine the natural frequencies, damping, and mode shapes of the wind turbine and rotor as a baseline for the LDV and our other tests. We also wanted to determine if LDV modal information could be obtained from a naturally (wind) excited wind turbine. We compared concurrently obtained accelerometer and LDV data in an attempt to assess the quality of the LDV data. Our test results indicate the LDV can be successfully used in the field environment of an installed wind turbine, but with a few restrictions. We were successful in obtaining modal information from a naturally (wind) excited wind turbine in the field, but the data analysis requires a large number of averaged data sets to obtain reasonable results. An ultimate goal of this continuing project is to develop a technique that will monitor the health of a structure, detect damage, and hopefully predict an impending component failure.
Book Synopsis High-speed Laser Anemometer System for Intrarotor Flow Mapping in Turbomachinery by : J. Anthony Powell
Download or read book High-speed Laser Anemometer System for Intrarotor Flow Mapping in Turbomachinery written by J. Anthony Powell and published by . This book was released on 1982 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Application of a Laser Doppler Velocimetry System to Flow Velocity Measurements in a Transonic Compressor by : Jeffrey Alan Harrison
Download or read book The Application of a Laser Doppler Velocimetry System to Flow Velocity Measurements in a Transonic Compressor written by Jeffrey Alan Harrison and published by . This book was released on 1978 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laser doppler velocimeter (LDV) system was developed and utilized to measure the flow velocities in the axial and tangential directions behind the rotors of a single stage transonic compressor. The backscatter mode was used to acquire the scattered light signals from particles that were seeded into the airflow upstream of the compressor. The light signals were generated as the particles traversed a fringe pattern produced by the intersection of two laser beams. The LDV system proved that it was possible to make velocity measurements in the transonic compressor. The results revealed a variation of the flow velocity in both the axial and tangential directions due to the formation of a wake caused by the passage of rotor blades. The velocity measurements were comparable to those acquired through pressure probe measurements. (Author).
Book Synopsis Laser Doppler Vibrometry for Cardiovascular Monitoring and Photoacoustic Imaging by : Laura Mignanelli
Download or read book Laser Doppler Vibrometry for Cardiovascular Monitoring and Photoacoustic Imaging written by Laura Mignanelli and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Application of a Laser Doppler Velocimetry System to Flow Velocity Measurements in a Transonic Compressor by :
Download or read book The Application of a Laser Doppler Velocimetry System to Flow Velocity Measurements in a Transonic Compressor written by and published by . This book was released on 1978 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A laser doppler velocimeter (LDV) system was developed and utilized to measure the flow velocities in the axial and tangential directions behind the rotors of a single stage transonic compressor. The backscatter mode was used to acquire the scattered light signals from particles that were seeded into the airflow upstream of the compressor. The light signals were generated as the particles traversed a fringe pattern produced by the intersection of two laser beams. The LDV system proved that it was possible to make velocity measurements in the transonic compressor. The results revealed a variation of the flow velocity in both the axial and tangential directions due to the formation of a wake caused by the passage of rotor blades. The velocity measurements were comparable to those acquired through pressure probe measurements. (Author).
Book Synopsis High-speed Laser Anemometer System for Intrarotor Flow Mapping in Turbomachinery by : J. Anthony Powell
Download or read book High-speed Laser Anemometer System for Intrarotor Flow Mapping in Turbomachinery written by J. Anthony Powell and published by . This book was released on 1982 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Implementation and Evaluation of a Two-dimensional Laser Doppler Vibrometer System for Non-contact Monitoring of External Stress Loading of Aluminum Samples by : Paul Wesley Langston
Download or read book Implementation and Evaluation of a Two-dimensional Laser Doppler Vibrometer System for Non-contact Monitoring of External Stress Loading of Aluminum Samples written by Paul Wesley Langston and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis details the development and validation of a laser Doppler vibrometer-based measurement system that is capable of quantifying not only the normal vibration of a solid body but also the component of vibration that is parallel to the plane containing the surface of interest. LDV manufacturers produce various devices that capture 3D measurements in a beam configuration that can be used to decompose the measured signals into not only the normal velocity of the surface of an object but also two orthogonal in-plane components of the vibration. It was a slightly simplified two-dimensional version of this approach that was chosen for implementation in the Wave Physics Lab using individual components to create a cheaper, more flexible system than those produced by companies such as Polytec. The goal of this system is to facilitate the exploration and discovery of areas and applications where 2D measurement may provide a more complete and precise view of the physics of different phenomena. Upon completion of the system development and validation, a study was done that sought to measure the acoustoelastic effect in an Aluminum plate by measuring how increasing loads alter both the normal and in-plane components of Lamb wave propagation in the plate. The acoustoelastic effect is the effect of stress on wave speed caused by non-linearity in the propagation medium.
