Дисертації з теми "Turbine blade vibration"
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1
Esu, Ozak O. "Vibration-based condition monitoring of wind turbine blades." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21679.
Повний текст джерелаАнотація:
Significant advances in wind turbine technology have increased the need for maintenance through condition monitoring. Indeed condition monitoring techniques exist and are deployed on wind turbines across Europe and America but are limited in scope. The sensors and monitoring devices used can be very expensive to deploy, further increasing costs within the wind industry. The work outlined in this thesis primarily investigates potential low-cost alternatives in the laboratory environment using vibration-based and modal testing techniques that could be used to monitor the condition of wind turbine blades. The main contributions of this thesis are: (1) the review of vibration-based condition monitoring for changing natural frequency identification; (2) the application of low-cost piezoelectric sounders with proof mass for sensing and measuring vibrations which provide information on structural health; (3) the application of low-cost miniature Micro-Electro-Mechanical Systems (MEMS) accelerometers for detecting and measuring defects in micro wind turbine blades in laboratory experiments; (4) development of an in-service calibration technique for arbitrarily positioned MEMS accelerometers on a medium-sized wind turbine blade. This allowed for easier aligning of coordinate systems and setting the accelerometer calibration values using samples taken over a period of time; (5) laboratory validation of low-cost modal analysis techniques on a medium-sized wind turbine blade; (6) mimicked ice-loading and laboratory measurement of vibration characteristics using MEMS accelerometers on a real wind turbine blade and (7) conceptualisation and systems design of a novel embedded monitoring system that can be installed at manufacture, is self-powered, has signal processing capability and can operate remotely. By applying the conclusions of this work, which demonstrates that low-cost consumer electronics specifically MEMS accelerometers can measure the vibration characteristics of wind turbine blades, the implementation and deployment of these devices can contribute towards reducing the rising costs of condition monitoring within the wind industry.
2
Kelen, Peter. "A finite element analysis of the vibration characteristics of rotating turbine blade assemblies." Thesis, University of Surrey, 1985. http://epubs.surrey.ac.uk/2098/.
Повний текст джерела
3
Flood, Robert C. "Vibrations of an isolated wind turbine blade using the finite element method." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91089.
Повний текст джерелаАнотація:
The finite element method is applied to an isolated and twisted wind turbine blade which is rotating in a vertical plane to determine its structural dynamic characteristics. The equations of motion are formulated for a rotating beam with flap and lead-lag degrees of freedom subjected to nonsymmetric bending. Using a variational approach, a blade finite clement is developed from these equations of motion. Additionally, expressions are formulated for the elastic strain energy and kinetic energy of a rotating wind turbine blade. Lagrange's equation is applied to these energy expressions and an isoparametric finite element based on three dimensional elasticity and quadratic interpolation functions is developed.
Both sets of finite element equations are implemented in a general purpose computer program to solve the structural dynamics eigenvalue problem and results compare favorably with published data for the cases of a nontwisted cantilevered beam both at rest and while rotating. A blade finite element model of a 10KW horizontal axis wind turbine blade is presented and its lowest modes of vibration are calculated for the cases of the blade at rest and in operation at rotor speeds up to 250 RPM.M.S.
4
Cigeroglu, Ender. "Development of microslip friction models and forced response prediction methods for frictionally constrained turbine blades." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1181856489.
Повний текст джерела
5
Tartibu, Kwanda. "A simplified analysis of the vibration of variable length blade as might be used in wind turbine systems." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/1244.
Повний текст джерелаАнотація:
Vibration is an inherent phenomenon in dynamic mechanical systems. The work undertaken in this thesis is to identify natural frequencies of a variable length blade. Therefore designers can ensure that natural frequencies will not be close to the frequency (or integer multiples) of the main excitation forces in order to avoid resonance. For a wind turbine blade, the frequency range between 0.5 Hz and 30 Hz is relevant. The turbine blade is approximated by a cantilever, therefore, it is fully constrained where attached to a turbine shaft/hub. Flap-wise, edge-wise and torsional natural frequencies are calculated.
The MATLAB program “BEAMANALYSIS.m” has been developed for the finite element analysis of a one dimensional model of the beam. Similarly, a three dimensional model of the beam has been developed in a finite element program Unigraphics NX5. The results found using the MATLAB program are compared with those found with NX5. Satisfactory agreement between the results is found for frequencies up to almost 500 Hz. Additionally, the frequencies one might expect in an experiment are identified.
Experimental modal analysis has been performed on a uniform and stepped beam made of mild steel to extract the first five flap-wise natural frequencies. The results found have been compared to numerical results and the exact solution of an Euler-Bernoulli beam. Concurrence is found for the frequency range of interest. Although, some discrepancies exist at higher frequencies (above 500 Hz), finite element analysis proves to be reliable for calculating natural frequencies.
Finally, the fixed portion and moveable portion of the variable length blade are approximated respectively by a hollow and a solid beam which can be slid in and out. Ten different configurations of the variable length blade, representing ten different positions of the moveable portion are investigated. A MATLAB program named VARIBLADEANALYSIS.m was developed to predict natural frequencies. Similarly three dimensional models of the variable length blade have been developed in the finite element program Unigraphics NX5.This work was supported by the Research office of CPUT.
6
Zdunek, Agnieszka Izabela. "Prediction of natural frequencies of turbine blades for turbocharger application : an investigation of the finite element method, mathematical modelling and frequency survey methods applied to turbocharger blade vibration in order to predict natural frequencies of turbocharger blades." Thesis, University of Bradford, 2014. http://hdl.handle.net/10454/7328.
Повний текст джерелаАнотація:
Methods of determining natural frequencies of the D76D88, B76D88, A86E93, C86G90, C86L90 and C125L89 turbine wheel designs for various environmental conditions were investigated by application of Finite Element Analysis and beam theory. Modelling and simulation methods were developed ; the first method composed of 15 finite element simulations ; the second composed of 15 finite element simulations and a set of experimental frequency survey results; the third composed of 5 simulations , an incorporated mathematical model and a set of experimental frequency survey results. Each of these methods was designed to allow prediction of resonant frequency changes across a range of exhaust gas temperature and shaft rotational speed. For the new modelling and simulation methods, an analysis template and a plotting tool were developed using Microsoft Excel and MATLAB software. A graph showing a frequency-temperature-speed variations and a Campbell Diagram that incorporates material stiffening and softening effects across a range of rotational speeds was designed, and applied to the D76D88, B76D88, A86E93, C86G90, C86L90 and C125L89 turbine wheel designs. New design methodologies for turbine wheels were formulated and validated, showing a good agreement with a range of data points from frequency survey, strain-gauge telemetry and laser tip-timing test results. The results from the new design method were compared with existing single compensation factor methodology, and showed a great improvement in accuracy of prediction of modal vibration. A new nomenclature for the mode shapes of a turbocharger’s blade was proposed, designed and demonstrated to allow direct identification of associated mode shape. It is concluded that Finite Element Analysis combined with the frequency survey is capable of predicting changes in turbine natural frequencies and, when incorporated into the existing turbine design methodology, resulted in a major improvement in the accuracy of the predictions of vibration frequency.
7
Van, Dyke Jason. "Modeling Behaviour of Damaged Turbine Blades for Engine Health Diagnostics and Prognostics." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20312.
Повний текст джерелаАнотація:
The reliability of modern gas turbine engines is largely due to careful damage tolerant design a method of structural design based on the assumption that flaws (cracks) exist in any structure and will continue to grow with usage. With proper monitoring, largely in the form of periodic inspections at conservative intervals reliability and safety is maintained. These methods while reliable can lead to the early retirement of some components and unforeseen failure if design assumptions fail to reflect reality.
With improvements to sensor and computing technology there is a growing interest in a system that could continuously monitor the health of structural aircraft as well as forecast future damage accumulation in real-time.
Through the use of two-dimensional and three-dimensional numerical modeling the initial goals and findings for this continued work include: (a) establishing measurable parameters directly linked to the health of the blade and (b) the feasibility of detecting accumulated damage to the structural material and thermal barrier coating as well as the onset of damage causing structural failure.
8
Tournu, Erik. "Modélisation stochastique du comportement dynamique non linéaire d'un ailetage de turbine : application à une poutre avec contact oblique." Vandoeuvre-les-Nancy, INPL, 1996. http://www.theses.fr/1996INPL118N.
Повний текст джерелаАнотація:
Des méthodes d'analyse en dynamique stochastique sont étudiées pour une maquette avec contact oblique. Elles ont pour objet de déterminer les caractéristiques statistiques de la réponse de la structure non linéaire soumise à des sollicitations aléatoires. La maquette représente une ailette avec ses ailerons qui sont en contact avec les ailerons voisins. Cette maquette est modélisée par la théorie des poutres d'Euler-Bernoulli pour l'ailette et par le modèle curvilinéaire de Bouc-Wen pour la non-linéarité de contact. Les résultats de ce modèle de comportement sont comparés avec succès à ceux d'une maquette de laboratoire qui concrétise la poutre avec les contacts obliques, sollicitées par des processus aléatoires. Les caractéristiques du processus de réponse du modèle de comportement soumis à des sollicitations aléatoires sont déterminées par la méthode de Monte-Carlo basée sur la simulation numérique des processus à partir des densités spectrales et par la méthode de linéarisation stochastique gaussienne basée sur l'équation de Lyapunov. Les résultats de ces deux méthodes concordent et ont mis en évidence trois domaines de comportement: pour les faibles excitations, il y a adhérence, pour les excitations moyennes, il y a glissement avec effort tangentiel limité constant et pour les excitations élevées, il y a glissement avec effort tangentiel limité croissant
9
Horák, Petr. "Energetická bilance tvarů kmitání lopatky poslední řady parní turbíny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230409.
Повний текст джерелаАнотація:
Created methodology for calculating the potential deformation energy parts is described in this thesis. Calculation method uses the outputs of modal analysis, which is performed using computational modelling. The potential deformation energy parts are calculated for three cases. Two benchmark problems and one case of blade model. Blade geometry is received by 3D scanning and reconstruction of given specimen. Results of the potential deformation energy parts calculations are analyzed and conclusions are formulated.
10
Cantoni, Lorenzo. "Load Control Aerodynamics in Offshore Wind Turbines." Thesis, KTH, Kraft- och värmeteknologi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291417.
Повний текст джерелаАнотація:
Due to the increase of rotor size in horizontal axis wind turbine (HAWT) during the past 25 years in order to achieve higher power output, all wind turbine components and blades in particular, have to withstand higher structural loads. This upscalingproblem could be solved by applying technologies capable of reducing aerodynamic loads the rotor has to withstand, either with passive or active control solutions. These control devices and techniques can reduce the fatigue load upon the blades up to 40% and therefore less maintenance is needed, resulting in an important money savings for the wind farm manager. This project consists in a study of load control techniques for offshore wind turbines from an aerodynamic and aeroelastic point ofview, with the aim to assess a cost effective, robust and reliable solution which could operate maintenance free in quite hostile environments. The first part of this study involves 2D and 3D aerodynamic and aeroelastic simulations to validate the computational model with experimental data and to analyze the interaction between the fluid and the structure. The second part of this study is an assessment of the unsteady aerodynamic loads produced by a wind gust over the blades and to verify how a trailing edge flap would influence the aerodynamic control parameters for the selected wind turbine blade.På grund av ökningen av rotorstorleken hos horisontella vindturbiner (HAWT) under de senaste 25 åren, en design som har uppstod för att uppnå högre effekt, måste alla vindkraftkomponenter och blad stå emot högre strukturella belastningar. Detta uppskalningsproblem kan lösas genom att använda metoder som kan minska aerodynamiska belastningar som rotorn måste tåla, antingen med passiva eller aktiva styrlösningar. Dessa kontrollanordningar och tekniker kan minska utmattningsbelastningen på bladen med upp till 40 % och därför behövs mindre underhåll, vilket resulterar i viktiga besparingar för vindkraftsägaren. Detta projekt består av en studie av lastkontrolltekniker för havsbaserade vindkraftverk ur en aerodynamisk och aeroelastisk synvinkel, i syfte att bedöma en kostnadseffektiv, robust och pålitlig lösning som kan fungera underhållsfri i tuffa miljöer. Den första delen av denna studie involverar 2D- och 3D-aerodynamiska och aeroelastiska simuleringar för att validera beräkningsmodellen med experimentella data och för att analysera interaktionen mellan fluiden och strukturen. Den andra delen av denna studie är en bedömning av de ojämna aerodynamiska belastningarna som produceras av ett vindkast över bladen och för att verifiera hur en bakkantklaff skulle påverka de aerodynamiska styrparametrarna för det valda vindturbinbladet.
11
Breslavsky, D. V., O. K. Morachkovsky, and N. V. Shyriaieva. "Nonlinear vibrations and long-term strength of turbine blades." Thesis, National Technical University "Kharkov Polytechnic Institute", 2010. http://repository.kpi.kharkov.ua/handle/KhPI-Press/41290.
Повний текст джерелаАнотація:
The method of a durability estimation of rotating turbomachinery blades at forced flexural-flexural-torsional vibrations is offered. The method is based on the methods of Continuous Damage Mechanics and the accurate strain analysis of the pre-twisted blades at the nonlinear vibrations with moderate displacements. The method to solve the strain analysis problem and turbomachinery blades high-cycle fatigue damage estimation as a result of nonlinear vibrations is presented.
12
Damborský, Petr. "Výpočtová a experimentální analýza napjatosti turbinové lopatky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228577.
Повний текст джерелаАнотація:
This diploma thesis deals with dynamic analysis of the steam turbine blade. This blade is part of the last row of low pressure level of steam turbine. Computational analysis has been performed in first part using FEM and software ANSYS. A Transient analysis has been used to solve forced vibrations. Main goal is to obtain a behavior of main stresses and its directions as a function of loading of the blade in the crack initiation area. Second part deals contain a an experiment. Experiment has been set up to perform a modal analysis which is necessary to obtain a fundamental numbers. Then the vibration of the blade has been performed. To perform this experiment same edge conditions as which has been used during the computational analysis. Goal is the same as in the first part – obtain a behavior of main stresses and its directions as a function of loading of the blade in the crack initiation area. The comparison of results obtained during experimental analysis and computational analysis has been performed in the last part of the thesis. Also the question if any geometrical nonlinearities appeared during analyses is answered.
13
Abouhnik, Abdelnasser Abouzid. "An investigation into vibration based techniques for wind turbine blades condition monitoring." Thesis, Manchester Metropolitan University, 2012. http://e-space.mmu.ac.uk/313141/.
Повний текст джерелаАнотація:
The rapid expansion of wind power has been accompanied by reported reliability problems and the aim is to provide a means of increasing wind turbine reliability, prevent break downs, increase availability and reduce maintenance costs and power outages. This research work reports the development of condition monitoring (CM) for early fault detection in wind turbine blades based on vibration measurements. The research started with a background and a survey of methods used for monitoring wind turbines. Then, finite element modelling (FEM) of three bladed horizontal axis wind turbine (HAWT) was developed to understand the nature and mechanism of the induced vibration. A HAWT test rig was constructed and equipped with computerised vibration measuring system for model verification. Statistical and spectral processing parameters then were used to analyse vibration signals that collected in healthy and faulty cases. Results obtained using time and frequency based techniques are not suitable for extracting blades condition related information. Consequently, empirical mode decomposition method (EMD), principal component analysis method (PCA) and continuous wavelet transform (CWT) are applied for extraction blade condition related features from the measured vibration. The result showed that although these methods generally proved their success in other fields, they have failed to detect small faults or changes in blade structure. Therefore, new techniques were developed using the above mentioned methods combined with feature intensity level (FIL) and crest factor. Namely, those are EDFIL, RMPCA and wavelet based FIL. The new techniques are found to be reliable, robust and sensitive to the severity of faults. Those analysis techniques are suitable to be the detection tool for an integrated wind turbine condition monitoring system. Directions for future work are also given at the end of the thesis.
14
Olafsson, Sveinn V. "Random vibrations of bladed-disk assembly under cyclostationary excitation." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43261.
Повний текст джерелаАнотація:
Random vibration of a bladed-disk assembly is studied. A stochastic model for the excitation is developed. A unique feature of this model is the statistical periodicity of the blade forces called cyclostationary. A random process is called wide sense eyeclostationary and its statistics are periodic in time. Factors like the turbulent nature of the flow around the blades, the variability in their geometry, and their nonuniform deterioration contribute to the uncertainty in the excitation. In periodic structures, like the bladed-disk assembly, small variation in the blade excitation may lead to high variability in the response.
The model developed includes both random and deterministic excitation. A comparison of the responses due to the random and the deterministic part shows the significance of taking into account the variability in the blade forces.
Therefore the assumption that the blade forces are all equal, used by all methods for vibration analysis of bladed disk assemblies, may lead to erroneous estimates of their response, reliability and expected life.
It is shown that the response is a cyclostationary process. Therefore the cyclostationary property is preserved from the input to the output. Furthermore the frequency of the second moment of the response is equal to two times the frequency of the excitation.Master of Science
15
Lackner, Matthew 1980. "Vibration and crack detection in gas turbine engine compressor blades using Eddy current sensors." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/28895.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, September 2004.Includes bibliographical references (p. 97).
(cont.) in the ECS signal, no definitive method for sensing blade vibration using an ECS has yet been developed.
High cycle fatigue (HCF) cracks generated by compressor blade vibrations are a common source of failure in gas turbine engines. Current methods for crack detection are costly, time consuming, and prone to errors. In-situ blade vibration detection would help operators avoid critical engine speeds, and help infer the presence of cracks via a change in the mode of a blade. Blade vibrations can be detected using non-contacting sensors like optical sensors, or contacting sensors like strain gauges. These methods have drawbacks that make them poorly suited for installation in a gas turbine engine. Eddy Current Sensors (ECS) have numerous advantages over other vibration detection methods. This thesis aims to use ECS's for vibration detection. Testing was performed in a spin pit rig in the Gas Turbine Lab at the Massachusetts Institute of Technology. The rig contained a rotor on which three test blades spun, and strain gauge and ECS data were extracted from the rig. Magnet arrays were used to provide an excitation force to the blades, causing them to vibrate as they were spinning. Force hammer testing was used to determine the resonant frequencies and mode shapes of the test blades, as well as transfer functions from the strain gauges to the blade tip acceleration. These transfer functions allowed for independent knowledge of the blade vibration behavior. The case of a cracked blade was also considered. Estimates were performed to determine the proper location and length of a crack in the test blade. A 10 mm edge crack was created in a test blade. The crack was found to lower the resonant frequency of the first torsion mode of the blade by 0.2%, and to alter the transfer function between strain and tip acceleration. While some evidence of the blade vibration appears
by Matthew Lackner.
S.M.
16
Agnese, Fabio. "Enhanced vibration damping materials and structures for wind turbine blades inspired from auxetic configurations." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653091.
Повний текст джерелаАнотація:
An extensive analysis of the current applications and possible employments of auxetic materials and configurations is presented. These novel materials show a negative Poisson's ratio and, potentially, enhanced mechanical properties. Despite a substantial amount of publications can be found in literature about auxetic material properties, not many of these consider practical applications for them. Objective and novelty of this project is therefore the application of auxetic material and/ or auxetic inspired configurations to existing structures and in particular to wind turbine blades to modify their dynamic characteristics. Wind turbine blades are complex systems manufactured using polymer matrix composite materials and at present made of a combination of glass and carbon fibre · reinforced plastic (GFRP-CFRP). Total damping in a blade is a combination of aerodynamic and structural loss factors, the latter being related to the inherent damping of the material. The two fundamental modes of vibration related to bending are of flapwise and edgewise type. The structural damping is material dependent, therefore the amount of structural damping available for these two vibration modes is the same. However, for the flapwise mode, the aerodynamic damping plays a very important role for the overall modal damping r.atio, whereas for the edgewise mode the only damping mechanism present is the str.uctural one. As a consequence, only a low value of loss factor can be achieved in the edgewise direction. The first aim of this project is then to demonstrate how auxetic inspired structure can be successfully applied to increase the loss factor of the blade in the edgewise direction of vibration. To this end several solutions have been investigated starting from the utilisation of 3D auxetic foams. They showed an effective increase in loss factor but limited by the fact that at present these foams present a low stiffness. Other solutions considered macro composites with shaped fibres and a novel damper design. Both these solutions have been analysed and characterised either by FE analysis and laboratory testing.
17
Hoell, Simon. "Optimal feature projections for enhanced vibration-based damage identification with an application to wind turbine blades." Thesis, University of Aberdeen, 2016. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=231272.
Повний текст джерела
18
Lošák, Petr. "Optimalizace modálního tlumení lopatek vysokotlakých stupňů parních turbín." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233951.
Повний текст джерелаАнотація:
Steam turbine rotor is a very complicated assembly, typically consists of several rotor rows. Due to design limitations and increasing demands on the efficiency of the steam turbines, it is practically impossible to avoid all of the resonant states. The significant vibrations can occur, for example, due to passing resonance state during turbine start up or run out. In the worst case the turbine operates state is close to the resonance state of the rotor row. This leads to the significant oscillation of the bladed disk, and may results in the blade (or blade to disk joints) high cycle fatigue. These parts are highly loaded components and any cracks are unacceptable. Therefore it is absolutely necessary to damp vibration by using, for example, passive damping elements. The damping element analyzed in this thesis is a strap with an isosceles trapezoidal cross section, which is placed in the circumferential dovetail groove in the blade segmental shrouding. The sliding between the contact surfaces leads to the dissipation of energy which causes decreasing of undesirable vibrations. The main aim is to design the optimal dimensions of the strap cross-section with a view to the most effective damping of vibration for a particular turbine operating state. Considered bladed disk has 54 blades which are coupled in 18 packets by segmental shrouding. The damping element is paced in circumferential dovetail groove created in the shrouding. This type of damping element is suitable especially for damping vibrations in the axial direction and only with the mode shape with the nodal diameters. The modal properties of the bladed disk are influenced by the sliding distance. Since the friction force depends on centrifugal force acting on the damping element and on the angle of the side walls of the strap and groove, the sliding distance can be influenced by the damping element dimensions. During the optimization process the best possible size of middle width, height and angle of damping element cross-section is searched. The strap weight, contact area size and flexural stiffness of damping element can be influenced by these parameters. Their change has also impact on the size of the contact pressure and thus on the size of relative motion as well. As stated previously, the damping efficiency is influenced by the relative motion between the damping element and shrouding. Numerical simulation in time domain is very time-consuming, especially for systems containing nonlinearities. In order to verify dynamic behavior of the computational model with the passive friction element in numerical simulations, the simplified model is created. The model is created in the ANSYS environment. The main requirement imposed on this model is to have as small number of degrees of freedom as possible, so the time needed to perform the simulation is reduced to a minimum. To satisfy this requirement the simplified model is a cantilever beam with rectangular cross section. The dovetail groove is created in this model in longitudinal direction. In this groove is damping element. In addition to damping element dimensions optimization, the influence of each design variable on model dynamic behavior is studied. The results are verified experimentally. Experiment also shows other interesting results that confirm the damping element influence on the modal characteristics. The gained knowledge is used to optimize the dimensions of the damping element in the model of the bladed disk.
19
Myhre, Mikkel. "Numerical investigation of the sensitivity of forced response characteristics of bladed disks to mistuning." Licentiate thesis, KTH, Energy Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1639.
Повний текст джерелаАнотація:
Two state of the art finite element reduction techniquespreviously validated against the direct finite element method,one based on classical modal analysis and another based oncomponent mode synthesis, are applied for efficient mistunedfree vibration and forced response analysis of several bladeddisk geometries. The methods are first applied to two testcases in order to demonstrate the differences in computationalefficiency as well as to validate the methods againstexperimental data. As previous studies have indicated, nonoticeable differences in accuracy are detected for the currentapplications, while the method based on classical modalanalysis is significantly more efficient. Experimental data(mistuned frequencies and mode shapes) available for one of thetwo test cases are compared with numerical predictions, and agood match is obtained, which adds to the previous validationof the methods (against the direct finite element method).
The influence of blade-to-blade coupling and rotation speedon the sensitivity of bladed disks to mistuning is thenstudied. A transonic fan is considered with part span shroudsand without shrouds, respectively, constituting a high and alow blade-to-blade coupling case. For both cases, computationsare performed at rest as well as at various rotation speeds.Mistuning sensitivity is modelled as the dependence ofamplitude magnification on the standard deviation of bladestiffnesses. The finite element reduction technique based onclassical modal analysis is employed for the structuralanalysis. This reduced order model is solved for sets of randomblade stiffnesses with various standard deviations, i.e. MonteCarlo simulations. In order to reduce the sample size, thestatistical data is fitted to a Weibull (type III) parametermodel. Three different parameter estimation techniques areapplied and compared. The key role of blade-to-blade coupling,as well as the ratio of mistuning to coupling, is demonstratedfor the two cases. It is observed that mistuning sensitivityvaries significantly with rotation speed for both fans due toan associated variation in blade-to-blade coupling strength.Focusing on the effect of one specific engine order on themistuned response of the first bending modes, it is observedthat the mistuning sensitivity behaviour of the fan withoutshrouds is unaffected by rotation at its resonant condition,due to insignificant changes in coupling strength at thisspeed. The fan with shrouds, on the other hand, shows asignificantly different behaviour at rest and resonant speed,due to increased coupling under rotation. Comparing the twocases at resonant rotor speeds, the fan without shrouds is lessor equally sensitive to mistuning than the fan with shrouds inthe entire range of mistuning strengths considered.
This thesisscientific contribution centres on themistuning sensitivity study, where the effects of shrouds androtation speed are quantified for realistic bladed diskgeometries. However, also the validation of two finite elementreduction techniques against experimental measurementsconstitutes an important contribution.
20
Drozdowski, Roman. "Berechnung der Schwingbeanspruchung in Radialturbinen unter Berücksichtigung realer Bauteilgeometrien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-83971.
Повний текст джерелаАнотація:
Der stetig anwachsende Bedarf und die innovative Weiterentwicklung im Bereich der Großdieselmotoren als Antrieb für Schiffe und Generatoranlagen erfordert ebenfalls die Weiterentwicklung der Abgasturbolader.
Hohe Leistungsfähigkeit und Wirtschaftlichkeit ist nur durch moderne Fertigungsverfahren und einer optimalen Ausnutzung der eingesetzten, hochwertigen Werkstoffe zu erreichen. Dies gilt insbesondere für die integralen Radialturbinenräder in Abgasturboladern, die aufgrund der hohen Betriebsbelastungen einen zentralen Punkt bei der Auslegung darstellen. Lebensdauerbegrenzend ist die hochzyklische Ermüdung aufgrund Resonanzschwingungen an der Beschaufelung der Turbinenräder.
Die vorliegende Arbeit soll die Auslegungsmethodik zur Berechnung und Beurteilung der zu erwartenden Schwingbeanspruchungen der Turbinenräder im Hinblick der realen Geometrie verbessern. Dazu wird ein einfaches Berechnungsmodell zur Identifizierung der kritischen Schaufelmoden und Bestimmung der Schwingbeanspruchungen im integralen Turbinenrad erarbeitet. Das Modell wird auf vorhandene Turbinenräder angewendet und aus den Ergebnissen werden Hinweise für eine systematische Beurteilung der Schaufelmoden, Knotendurchmesser und Schaufelgestaltung bezüglich der kritischen Schwingbeanspruchungen angegeben.
Desweiteren wird der Einfluss der Verstimmung (engl. Mistuning) des Schwingverhaltens realer, integraler Turbinenräder ausführlich im Hinblick auf die Schwingbeanspruchungen untersucht. Die wesentlichen Ursachen für die Verstimmung sind die innerhalb der Fertigungstoleranzen auftretenden Geometrieabweichungen der Schaufeln. Dabei wird ein Überblick über die typischen Geometrie- und Frequenzabweichungen Radialturbinen gegeben und Auswirkungen auf das Schwingverhalten des Rades wie Lokalisierung der Schwingformen und Amplitudenüberhöhungen ermittelt und in einen systematischen Zusammenhang mit den geometrischen Ursachen, der Komplexität der Schaufelschwingformen und Knotendurchmesser gestellt. Es zeigt sich, dass unter gewissen Voraussetzungen bei Radialturbinen KD0 und KD1 Schwingformen weniger sensibel auf die Verstimmung reagieren. Hieraus können Hinweise für die Verbesserung des Auslegungsprozess abgeleitet werden.
Die Kenntnis über das reale Schwingverhalten verstimmter Turbinenräder ermöglicht die korrekte Auswahl geeigneter Schaufeln zur Applikation von Dehnmessstreifen, wodurch eine sichere Beurteilung der Betriebsbeanspruchungen erst möglich wird.
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Моргун, Сергій Олександрович, Сергей Александрович Моргун та Sergii O. Morgun. "Напряженно-деформированное состояние конструктивно неоднородных лопаток турбомашин при их вибрациях". Thesis, Запорізький національний технічний університет, 2015. http://eir.zntu.edu.ua/handle/123456789/419.
Повний текст джерелаАнотація:
Моргун, С.О. Напруженно-деформований стан конструктивно неоднорідних лопаток турбомашин при їх вібраціях [Текст]: дис. … канд. техн. наук: 01.02.04 : захищена ....: затверджена…. /Моргун Сергій Олександрович. – Запоріжжя, 2015. – 157 с.UK: Дисертація присвячена визначенню параметрів напружено-деформованого стану конструктивно неоднорідних робочих лопаток турбомашин при їх вібраціях з використанням методу скінчених елементів. Розвинуті і теоретично обґрунтовані ефективні чисельні методи для розв’язання розглянутих в дисертації задач. Досліджено вплив геометричних характеристик лопаток, фізико-механічних властивостей матеріалу, температури газового потоку на частоти та форми коливань і напружено-деформований стан робочих лопаток турбомашин. Достовірність та адекватність розроблених математичних моделей підтверджена співставленням результатів з даними, отриманими з використанням пакету програм ANSYS та експериментально. EN: The thesis is devoted to the non homogeneous cooled single turbine blades and strain-deformed state parameters under vibration load by means of finite elements method usage. The effective numerical methods for the foregoing problems solution are also developed and theoretically approved. The turbine blades geometrical characteristics, their material physical and mechanical state and the gas flow temperature influence on their oscillation forms and frequencies, and strain-deformed state has been researched. The results of the research have been adopted by the obtained results comparison with the ANSYS program package’s solutions and experimental data. RU: Диссертация посвящена определению параметров напряженно-деформированого состояния конструктивно неоднородных лопаток турбомашин при их вибрациях с использованием метода конечных элементов. Приведена постановка и обоснование задач динамического поведения рабочих лопаток турбомашин. Развиты и теоретически обоснованы эффективные численные методы для решения рассмотреных в дисертации задач. Построены уточненные математические модели свободных и вынужденных колебаний, а также напряженно-деформированного состояния, позволяющие адекватно описывать динамическое поведение конструктивно неоднородных рабочих лопаток. Уравнения движения лопаток получены с использованием вариационного принципа Лагранжа II рода. Выполнен анализ сходимости полученных решений. Получены результаты количественного и качественного характера для лопаток с конструктивными неоднородностями, которые характеризуют особенности их поведения при вынужденных колебаниях, вызванных воздействием переменной газодинамической силы. Исследовано влияние геометрических характеристик лопаток, физико-механических свойств материала, температуры газового потока на частоты и формы колебаний и напряженно-деформированное состояние рабочих лопаток турбомашин. Достоверность и адекватность разработанных математических моделей подтверждена сопоставлением полученных результатов с данными, полученными с использованием пакета программ ANSYS и экспериментальным путем. Экспериментальные исследования частот и форм колебаний, как охлаждаемых, так и неохлаждаемых лопаток турбомашин проводились методом голографической интерферометрии. Параметры напряженно-деформированного состояния лопаток определялись на специальном вибровоздушном стенде с применением метода тензометрирования.
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Janicki, Grzegorz, Antonios Pezouvanis, Byron A. Mason, and Kambiz M. Ebrahimi. "Turbine blade vibration measurement methods for turbocharges." 2014. http://hdl.handle.net/10454/9842.
Повний текст джерелаАнотація:
NoThis paper presents and compares the most important and often used methods to measure turbine blade vibrations: use of strain gauges and telemetry system which is an intrusive method or, on the other site. The Blade Tip Timing (BTT) method known as Non-Intrusive Stress Measurement (System) NSMS. Both methods have advantages and disadvantages which are described below. This paper focused on synchronous vibrations, which are more important in terms of turbine blades fatigue prediction and design optimization.
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Li, Shih-Hsing, and 李志興. "Vibration Mode Study of Small Wind Turbine Plastic Blade." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16708698791039183048.
Повний текст джерелаАнотація:
碩士中華科技大學
飛機系統工程研究所
100
ABSTRACT Energy consumption becomes more and more important in the future of our live. The green energy of wind power is relatively much attention. Especially, the composite material small and medium-sized wind turbine blades take a major part in the domestic wind power market. In here, our research is concentrate at small injection molding of composite wind blades as research material. There are five different plastics are going to studies such as: Poly Butylene Terephathalate referred to as PBT, Poly phenylene sulfide referred to as PPS, polypropylene referred to as PP, NYLON and Poly Carbonate referred to as PC . Those five plastics will containing 40% fiber materials explore in the structure of mode shapes to study and compare. The material plastic blades structural strength is going to apply to the American Air-X 400Won superiority of the small wind turbines. On the other hand, research methods are going tap the test module to collect the leaf structure shapes and establish the modal database for numerical analysis. Beside, the MATLAB numerical calculation software and the ANSYS finite element analysis software modeling were used to analyze and compare the experiment results. The results will discuss of blades applicability as well as flaws in the process. Finally, the bending test and vibration database validation will compare the experimental design with the composite wind turbine blades of the basic theory. According to the origin design shape, the results we funded the most suitable material is PPS from five kinds of materials. For the PPS mechanical properties can be the less temperature sensitivity and the small knot vibration to system. During the procedure of injection, molding structural porosity defects on the small wind blades and micro-structural strength will be future related research. Keywords: Plastic Blade Vibration Mode, Vibration Mode, Vibration Testing, Modal Database.
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Chern, Chern-Kao, and 程國城. "Analyses of Stresses and Vibration for the Turbine Blade." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/58939131222393926771.
Повний текст джерелаАнотація:
碩士華梵大學
機電工程研究所
95
The aim of this paper is to analyze the static stress and vibration characteristics for the steam turbine blades using the finite element method. The turbine blades are vulnerable to induce creep deformation and crack defects under long term operation at high temperature. The strength of blades must be large enough to prevent the yielding and fatigue. In the meanwhile, the prevention of vibration resonance for turbine blades is important. The turbine blade’s model was constructed by using the graphic software, Solid Works. The finite element software, ANSYS, was employed to calculate the structural stress, natural frequency, and mode shape. The stress distributions of the cracked-blade subjected to the differential steam pressure and rotational motion were obtained to discuss the influence of the crack contained in the blade. It was found that the turbine blade will yield under the high rotation speed. Finally, the natural frequency and vibration modes were obtained to reveal the influence of the crack. It was found that the natural frequency for the cracked-blade is less than that of the blade free from the crack defect.
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Babawarun, Tolulope. "Improvement of vibration behaviour of small-scale wind turbine blade." Diss., 2020. http://hdl.handle.net/10500/27607.
Повний текст джерелаАнотація:
Externally applied loads from high winds or impacts may cause structural damage to the
wind-turbine blade, and this may further affect the aerodynamic performance of the blade.
Wind-turbine blades experience high vibration levels or amplitudes under high winds.
Vibrations negatively affect the wind flow on the blade. This project considers the structural
dynamic analysis of a small-scale wind turbine with a particular focus on the blade; it involves
the finite element model development, model validation and structural analysis of the validated
model. The analysis involves a small-scale wind-turbine structural response when subjected to
different loading inputs. The analysis is specifically focused on on-shore systems. The use of
small-scale wind-turbine systems is common however, apart from initial structural analysis
during design stages, these systems have not been studied sufficiently to establish their
behaviour under a variation of real-life loading conditions. On-shore wind turbines are often
designed for low-wind speeds and their structural strength may be compromised. In addition,
these systems experience widely-varying wind speeds from one location to another to an extent
that it is extremely difficult to achieve a uniform structural performance. The main reason for
solving this problem is to evaluate the structural response of the blade, with special emphasis
on an 800 W Kestrel e230i. This involves the calculation of the distribution of blade deflections and stresses over the wind-turbine blade under different loading conditions. To solve the
problem, a three-dimensional model of a Kestrel e230i blade was firstly developed in Autodesk
Inventor Professional using geometrical measurements that were taken in the mechanical
engineering laboratory. A 3D finite element model was developed in ANSYS using
approximate material properties for fiberglass obtained from the literature. The model was then
validated by comparing its responses with those from a number of static tests, plus a simple
impact test for comparison of the first natural frequency. Finally, a number of numerical tests
were conducted on the validated finite element model to determine its structural responses. The
purpose of the numerical analysis was to obtain the equivalent von Mises stress and
deformation produced in the blade. It was determined that under the examined different loading
conditions, a higher stress contour was found to occur around the mid-span of the blade. The
calculated maximum flexural stress on the blade was observed to be less than the allowable
flexural stress for fiberglass which is 1,770 MPa. As expected, the highest deformation
occurred at blade tip. The first critical speed of the assembled three-bladed wind turbine was found to be at 4.3 rpm. The first mode shape was observed to be in the flap-wise bending
direction and for a range of rotor speeds between zero and 608 rpm, three out of a total of five mode shapes were in the flap-wise bending direction. Future studies should address issues
relating blade vibrations with generated power, validation of dynamic tests, fluid-structural
interaction and introduction of bio-inspired blade system. Although the performance of the bioinspired
blade has not been studied in great detail, preliminary studies indicate that this system
has a superior performance.Mechanical and Industrial Engineering
M. Tech. (Electrical and Mining Engineering)
26
Hsiung, Wan-Ying, and 熊婉贏. "Vibration Analysis and Damage Detection of a Research-scale Wind Turbine Blade." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/87676210092876441145.
Повний текст джерелаАнотація:
碩士國立臺灣大學
土木工程學研究所
102
The objective of this study was to validate modal analysis, system identification and damage detection of small-scale rotating wind turbine blades in the laboratory and in the field. Here, wind turbine blades were instrumented with accelerometers and strain gages, and data acquisition was achieved using a prototype wireless sensing system. In the first portion of this study conducted in the laboratory, sensors were installed onto metallic structural elements that were fabricated to be representative of an actual wind blade. In order to control the excitation (rotation of the wind blade), a motor was used to spin the blades at controlled angular velocities. The wind turbine was installed on a shaking table for testing. Under the circumstance of the couple of rotating wind turbine blade and tower with base excitation to measure the signals of different rotation speed. On the other hand, the second part of this study which is field experiment utilized a small-scale horizontal axis wind turbine system mounted on the rooftop of a building at University of California, Davis. The model of this wind turbine is Bergey Windpower XL.1. Compared to the lab tests, the main difference was that the field tests relied on actual wind excitations (as opposed to a controlled motor). In laboratory test, the turbine blade divided into two cases, undamaged and damaged blades. Take two loose bolts connection in one of the turbine blade as damaged cases and use damage index to identify the damage occurrence in blade. In addition, the raw data from both laboratory tests and field tests were analyzed by signal processing and system identification techniques for deriving the model response of the blades. The Multivariate Singular Spectrum Analysis (MSSA), Covariance-driven Stochastic Subspace Identification method (SSI-COV) and Data-driven Subspace Identification method (SI-DATA) were used to identify the dynamic characteristics of the system. These above experiments confirmed that dynamic characterization of rotating wind turbines system was feasible, and the results will guide future wind turbine monitoring studies.
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Nanami, Norimichi. "Vibration and Structural Response of Hybrid Wind Turbine Blades." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8735.
Повний текст джерелаАнотація:
Renewable energy is a serious alternative to deliver the energy needs of an increasing world population and improve economic activity. Wind energy provides better environmental and economic benefits in comparison with the other renewable energy sources. Wind energy is capable of providing 72 TW (TW = 10^12 W) of electric power, which is approximately four and half times the world energy consumption of 15.8 TW as reported in 2006. Since power output extracted from wind turbines is proportional to the square of the blade length and the cube of the wind speed, wind turbine size has grown rapidly in the last two decades to match the increase in power output. As the blade length increases, so does its weight opening up design possibilities to introduce hybrid glass and carbon fiber composite materials as lightweight structural load bearing alternatives.
Herein, we investigate the feasibility of introducing modular composite tubulars as well as hybrid sandwich composite skins in the next generation blades. After selecting a target energy output, 8 MW with 80 m blade, airfoil geometry and the layup for the skin as well as internal reinforcements are proposed. They are incorporated into the computational blade via linear shell elements for the skin, and linear beam elements for the composite tubulars to assess the relationship between weight reduction and structural performance. Computational simulations are undertaken to understand the static and dynamic regimes; specifically, displacements, stresses, and vibration modes. The results showed that the composite layers did not exhibit any damage. However, in the balsa core of the sandwich skin, the von Mises stress exceeded its allowable at wind speeds ranging from 11.0 m/sec to 12.6 m/sec. In the blades with composite tubular reinforcement, two different types of damage are observed: a. Stress concentrations at the tubular-skin attachments, and b. Highest von Mises stress caused by the flapping bending moment. The vibration studies revealed a strong coupling mode, bending and twist, at the higher natural frequencies of the blade with tubular truss configuration. The weight saving measures in developing lighter blades in this study did not detract from the blades structural response for the selected load cases.
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Huang, Yu-Ting, and 黃昱婷. "Image based vs vibration based analysis of a research scale wind turbine blade." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/60646723330492401538.
Повний текст джерелаАнотація:
碩士國立臺灣大學
土木工程學研究所
102
The objective of this study was to validate modal analysis and system identification of an operating, small-scale, wind turbine system in the laboratory. In general, wind turbine blades were instrumented with accelerometers and strain gages, and data acquisition was achieved using a prototype wireless sensing system. In this study, an experiment was designed to control the rotation of wind turbine blades in the lab. In order to control the excitation (rotation of the wind blade), a motor was used to spin the blades at controlled angular velocities. Sensors were installed onto two different representative and metallic wind blades (i.e., damaged versus undamaged blade). Data measured by the contact sensors (accelerometers and strain gages) and the photographic images (camera) were recorded while the blade was operated at different speeds. First, to analyze the displacement/motion of the turbine blade, a photogrammetric approach was used. After 3D calibration of the imaging system, 3D positions are calculated using a stereo triangulation technique and digital images taken to track the 3D motion of the blade. Image measurement error induced by image analysis error and camera synchronization error was discussed. Second, the dynamic characteristics of the rotating blade were investigated. The Rodrigues’ rotation was applied to the data to extract the vibration signal due to rotation. Separation of the turbine blade natural frequencies and the rotating frequency can successfully be carried out. From which the residual signal can be used to identify the dynamic characteristics of turbine blade. Dynamic characteristic of undamaged and damage turbine blade was investigated.
29
Jheng, Siang-Jyun, and 鄭翔駿. "The Measurement Applications of Image Analysis at Structure Vibration Properties of Wind Turbine Blade." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/8fve6w.
Повний текст джерелаАнотація:
碩士國立臺北科技大學
土木工程系土木與防災碩士班
105
In the measurement of wind turbine blade vibration, various restrictions on the installation of contact sensors. Such as the signal line is easy to be pulled, wireless sensor power supply problems will cause measurement inconvenience. Although the image measurement technology is maturing, it’s not easy to measure small vibrations of fan blades in a wide range of rotation motion. In addition, the experimental processes still have a lot of irresistible external factors, such as light instability caused by experimental data is full of all kinds of noise. The noise is even greater than the vibration of the blade. The condition make the subsequent signal analysis is not easy. In order to analyze the measured vibration data, this study will capture the image data to do image processing and signal analysis. In the image analysis, this study uses camera image calibration, template matching, triangulation, coordinate transformation and so on. In the study, the frequency of the vibration of the target structure was found by filtering, Singular Spectrum Analysis (SSA) and Wavelet Packet Transform(WPT), filter out noise to find the frequency of vibration of the target structure and use these data to achieve the effect of structural health monitoring. The study also found that the use of image analysis will appear signals of multiple frequencies. And the study considers that it is not the phenomenon of structural vibration. This paper presents these multiple frequency phenomena and explains the cause of the multiplication phenomenon.
30
Wang, Min-Jou, and 王明州. "Analyze the Suppression Effect of Turbine Blade Vibration by Flywheel Damper Using the Finite Element Method." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/02409378375008481460.
Повний текст джерелаАнотація:
碩士南台科技大學
電機工程系
92
Considering the accuracy of frequency and stress, FEM is superior then lumped parameter dynamic program. However, FEM alone cannot obtain the blade overload under power fault. The dynamic simulating torsional response had been proved quite accurate by the experiment, but for the extended part of the blade, the credibility is relatively poor since the model is simple and crude. This thesis adopts torsional response simulation to get the analytic information which is employed by FEM and the mesh analysis of the blade. This thesis is to establish an appropriate mechanical system model for the rotor parts and the final three stages blades of a low-pressure turbine. It makes use of the verified dynamic program to simulate the torsional vibration of turbine-generator in the severe power fault (line-to-line short circuit). It explores the suppress effect of blade fatigue induced by vibration as the incident happens owing to the variation of the inertia of “Flywheel Damper” installed on the coupling. The Finite Element Method is aided to make the stress analysis of turbine blade details. On the basis of the finite element analysis software ANSYS. Firstly, we simulate the steam thrust added on last stage blades at ordinary time and probe which part on last stage blade bear the maximum force. Secondly, the vibration torque due to line-to-line fault has been added on the shaft, and probes the last stage blades under stress condition. Finally, the same finite element analysis software ANSYS is adopted to compare the stress condition of the blade with the flywheel damper of variant inertia. The research aimed on designing proper equipment to reduce vibration and limit vibration torque under network fault in order to lengthen the result of life-span to charge. Moreover, the utilization of 3D blade to simulate and find out which part bear the maximum strength is also good for overhaul consulting at ordinary times. Furthermore, enormous damages can be prevented. Keywords：FEM, turbine-generator, final three stages blades
31
Ming, Chen Hua, and 明振華. "Vibration Analysis of Cracked Turbine Blades." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/60080276945303135487.
Повний текст джерелаАнотація:
碩士國立中央大學
機械工程學系
86
This paper studies the dynamic behavior and vibration modes of cracked turbine-blade through numerical simulation by transfer method . Although the usual turbine blades have complex geometric shape , such as a pre-twisted angle , width and depth , which all change with the length of blade . But the precision of blade's simulation by general beams has been proved well in many papers .Therefore , Timoshenko contiuous beam is selected in the present thesis . Besides , blade is often connected with a flexible disk which induces the vibration of blade . Hence the disk's influences in vibration behavior of a blade are also considered in this paper . The way of crack-modeling adopts the local flexibility matrix , and then the system's governing equation is solved by transfermethod . Finally the system's natunal frequency and vibration modes can be obtained . This paper shows the influences of a crack location and the crack sizeon blade's system . The effects of transverse shear deformation , rotary inertia and the pre-twisted angle are taken into account . It is found that the crack has great influences on the dynamic characteristics of the rotating blade .
32
QIN, CUN, and 秦純. "Vibration analysis of turbine-generator shafts and blades." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/96605876665306428697.
Повний текст джерела
33
Chang, I.-Chieh, and 張奕傑. "Vibration Analysis of Rotating Vertical Axis Wind Turbine Blades." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26983033782497948789.
Повний текст джерелаАнотація:
碩士國立臺灣大學
應用力學研究所
99
Wind power is the most potential source of renewable energy. There are two categories of modern wind turbines, namely horizontal axis wind turbines (HAWT) and vertical axis wind turbines (VAWT). Vertical axis wind turbines have the major benefit of operation that is independent of the wind direction. Other benefits include easier installation and lower noise radiation than the horizontal axis wind turbines. Therefore they have great potential for applications in the urban area. Nevertheless, higher efficiency is offered by a horizontal wind turbine as it has blades in perpendicular to direction of wind and hence receives more power for rotation. To ensure that the blades operate effectively, it is important that that their structure is dynamically safe when in rotation. There has been a growing interest in the investigation of free vibration characteristics of rotating beams because the topic plays an important role in the design of shafts, turbine blades, propellers and many other rotating structures. In this present paper, we use Hamilton’s principal to derive the dynamic governing equations for the rotational slender blade. We especially take rotational velocity which is a very important parameter when rotating into consideration. Theoretical natural frequencies and mode shapes for some illustrative examples are calculated and compared with the simulation of ANSYS Workbench. These results are discussed and compared with published ones, and we can predict the first few lower natural frequencies quite accurately. Vertical axis wind turbine is verified that the theoretical model can provide mechanical insight into the design of the blades. The vertical axis wind turbine blades are flexible, highly dynamic structure, with many natural modes of vibration that must be carefully analyzed to ensure the blades are dynamically stable under all operating conditions.
34
YI, HSIAO CHENG, and 蕭振益. "The crack effects to the vibration behavior of large size turbine blades." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/54238113995408615448.
Повний текст джерелаАнотація:
碩士中華大學
機械與航太工程研究所
94
The purposes of this thesis are to study the crack effects to the vibration behavior of large size turbine blades. The vibration caused by the crack is not only to effect the dynamic characteristics of the blade, but also the dynamic characteristics of grouped blade system. Because grouped blade system is the periodically coupled blades system, once a crack appears in any blade of it, that will make the system to experience the vibration phenomenon, which causes the vibration energy and stress around the crack of the blade and then destroy the system﹒In this thesis, the dynamic characteristics caused by the crack effects are investigated. The equation of motions and boundary conditions are derived by Hamilton’s principle. The software MATLAB will be used to simulate the mathematical model developed in this thesis. The crack blade can be considered as two segments of blade. Crack effect is modeled as torsional spring to connect the two segments with proper compatibility conditions. Because of the special boundary conditions of grouped blade system, the cantilever modes and fixed-supported modes will be excited. Finally, the parameters of crack location, crack length and crack in the blade are considered to elucidate the dynamic behavior of the group blades. Through the combination of exploring process of the analysis, the knowledge are developed and an erected in a manner to upgrade technology in our living.
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You, Kai-Siang, and 游凱翔. "Non-linear vibration of blade bending and fluttering of vertical axis wind turbines." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75579716003645920511.
Повний текст джерелаАнотація:
碩士國立臺灣大學
應用力學研究所
101
Vertical axis wind turbine has the benefit of operation that is independent of the direction, and less noise. In recent years there are more and more people involved in research of VAWTs. In this present paper, we adopt NACA0015 to be analysis model. Using nonlinear analysis to analyze resonance and stability of amplitude – force frequency relation of wind blade . The nonlinear term is cause by the axial force that owing to bending deformation. We start form basic theory of mechanics of materials. To find the strain potential energy and retained to the second order nonlinearity. Consider the kinetic energy of operating VAWTs. Using the Hamilton’s principle to derive the governing equation and then dimensionless the equation. Consider real condition to simplify the governing equation. Appling Galerkin’s method to equation and get the amplitude force frequency relation for different frequency. Using perturbation methods to designate the stable and unstable zones. In linear system the leading edge direction is uncouple, and the other bending direction is couple with torsion. So we first consider the bending and torsion coupling equation. In the last part of section we consider the two bending equation to compared with above. Simultaneously applied Runge-Kutta fourth order method to solve equation. And using FFT to analyze the result. Then use different method to present the result. Finally make a verification by compare the analysis and numerical result.
36
Li, Wen-Yang, and 李文揚. "Torsional vibration analysis for wind-turbine generator blades and shafts subject to power system excitations." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/40752105442035817051.
Повний текст джерелаАнотація:
碩士高苑科技大學
電子工程研究所
98
Wind energy is one of the most popular and economic renewable energy generations. According to the statistics, there is about 3GW wind energy power potentially in Taiwan. If the grid-connected wind turbine generator is subjected to the network faults, the induced electromagnetic torque gives rise to torsional torque stresses on turbine drive train components, namely blades and high/low speed shafts. This project employs a single induction machine-infinite system of middle voltage level containing a fixed-speed wind turbine, in order to investigate the wind turbine torque behaviors owing to network faults. From the simulation results, it is found that all the turbine components are sensitive to unidirectional component excitation (the real power pulsation). Therefore,the worst-case impact is simulated and resulted from threephase-to-ground fault. The auto-reclosing time of circuit breaker next to wind power plant should be carefully examined in order to ensure long-term safety operation.
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Huang, Chih-Fang, and 黃志方. "Depressing the Torque Vibrations of Turbine Shafts and Blades by using a Mechanical Filter." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/12899199264949293789.
Повний текст джерелаАнотація:
碩士國立中山大學
電機工程學系
87
This thesis proposes a mechanical filter to depress the torque vibrations on turbine shafts and blades excited by power system faults. Due to the power system faults, the electromagnetic torque at system frequency produces the torsional stress to impact the turbine-generator shafts and blades. Therefore, the system frequency is designed as the resonant frequency of the mechanical filter installed between generator and rectifier in series. This thesis uses conversion methods from the mechanical elements of turbine-generator shafts and blades to the equivalent electrical network ones. The dynamic responses of low-pressure steam turbine blades can be obtained by fast computer calculation. In this thesis, our attention is concentrated on NO.3 nuclear power station generator sets (951MW) of the Taiwan Power Corporation to establish the simulation models proposed. According to the simulation results, it can be found that a mechanical filter design presents the good performance for improving the torque vibrations on turbine shafts and blades induced by the L-L-L-E and L-L faults. Also the vibration torque in most of turbine blades are dominated by the system frequency response. Therefore, the system-frequency mechanical filter could significantly improve the vibrating behaviors of blades. It is proposed to provide a good approach for reducing the torque vibrations on the turbine generator in this thesis.
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Wu, Yun-Peng, and 吳運鵬. "Three-degree-of-freedom system of linear vibration of blade bending and fluttering of vertical axis wind turbines." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/10149293309873164243.
Повний текст джерелаАнотація:
碩士國立臺灣大學
應用力學研究所
100
Compared to horizontal axis wind turbines, vertical axis wind turbines have the benefit of operation that is independent of the wind direction, lower wind speed to start operation, and less noise. The vibration of blade can be regarded as vibration of a beam. How to support the ends of the beam affect the vibration very much. In this present paper, we start from the energy method of Hamilton’s principle, derive the dynamic governing equations for the blade, which has three degree of freedom (includes bending and fluttering). The key variable to keep the three degree of freedom coupled is the distance from center of gravity to shear center, . When the cross-section of blade is symmetrical, the value of is zero, which means the three degree of freedom will decouple. We creat the model of NACA0015 small size blade. The NACA series blades are asymmetric, so we can keep the three degree of freedom coupled in calculation. We discrete the space and governing equation by finite difference method, solve the cases of simply support and fixed support, respectively. Then use ANSYS Workbench to do the modal analysis. Thus we obtain the natural frequency and mode shape of theory and simulation, respectively. The two results are similar in low frequency mode. By the way we use in this study, we can vary the natural frequency while design the blade, avoiding resonance in operation. Otherwise, we also do the modal testing of small size NACA0015, expect to compare the result of experiment and simulation. Due to the lack of experimental equipment, the boundary conditions of the modal testing can not coincide with the simulation. Finally we build an experiment process only, without data to compare with simulation.
39
蔡文昌. "Accurate models and control methods for the vibrations of shafts and blades of steam turbine-generators." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/99901504796806341669.
Повний текст джерела
40
Lin, Chi-Hshiung, and 林祺祥. "Improving the Torque Vibrations on Shafts and Blades of a Large-scale Steam Turbine Generator Set." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/90570995706992039439.
Повний текст джерелаАнотація:
博士國立中山大學
電機工程學系研究所
88
Abstract Recently, the expansion in power system capacities leads to the development of large-scale steam turbine generator units. As a result, a fault on the power system may induce large fault current and give rise to serious torque vibrations on turbine shafts and blades, which ought to be improved in order for the reliable operation of a turbine-generator system. In the thesis, countermeasures are proposed from electrical viewing-point and from mechanical viewing-point respectively. Based on electrical viewing-point, the apparatus in the generator stator side and in the rotor side respectively is applied to suppress the induced disturbing source. The high temperature superconductive fault current limiter bank introduces a large normal-state resistance to restrict the dc component of stator fault current. The choke coil acts as a low pass filter to restrict the system-frequency component of field fault current. Both of them lead to the reduction in electromagnetic torque of system-frequency and effectively improve the vibrating behavior of blades. Based on mechanical viewing-point, it is found from the electromechanical analysis that the Generator/LP-Turbine shaft stiffness and the Generator rotor inertia constant determine the responses of all turbine blades. Once the stiffness on this shaft section is reduced by replacing the rigid shaft coupling with a flexible one or the inertia constant is augmented by a system-frequency mechanical filter, the blades become intrinsically less responsive to electrical disturbances. As a result, the blades will bear less stress impact and can be designed with smaller safety factor. On the other hand, LP-turbine long blades operated in corrosive environment and underwent the statistical stress impact due to randomly distributed negative sequence current is studied also. In such situation, the blades may be subjected to corrosion fatigue and the long term effects of power system unbalance may become the cause of fatigue damage on blades though the negative sequence current is still within the limitation of generator thermo-rating. As a result, turbine blades are possibly unprotected by traditional system unbalance protection scheme. Therefore, it will depend on the operating environments and the blade materials whether such long-term stress can be neglected or not. If there is the potential of blade damage, one has to reconsider the I2 protection settings and rearrange the load distribution to limit the system unbalance.
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Drozdowski, Roman. "Berechnung der Schwingbeanspruchung in Radialturbinen unter Berücksichtigung realer Bauteilgeometrien." Doctoral thesis, 2011. https://tud.qucosa.de/id/qucosa%3A25918.
Повний текст джерелаАнотація:
Der stetig anwachsende Bedarf und die innovative Weiterentwicklung im Bereich der Großdieselmotoren als Antrieb für Schiffe und Generatoranlagen erfordert ebenfalls die Weiterentwicklung der Abgasturbolader.
Hohe Leistungsfähigkeit und Wirtschaftlichkeit ist nur durch moderne Fertigungsverfahren und einer optimalen Ausnutzung der eingesetzten, hochwertigen Werkstoffe zu erreichen. Dies gilt insbesondere für die integralen Radialturbinenräder in Abgasturboladern, die aufgrund der hohen Betriebsbelastungen einen zentralen Punkt bei der Auslegung darstellen. Lebensdauerbegrenzend ist die hochzyklische Ermüdung aufgrund Resonanzschwingungen an der Beschaufelung der Turbinenräder.
Die vorliegende Arbeit soll die Auslegungsmethodik zur Berechnung und Beurteilung der zu erwartenden Schwingbeanspruchungen der Turbinenräder im Hinblick der realen Geometrie verbessern. Dazu wird ein einfaches Berechnungsmodell zur Identifizierung der kritischen Schaufelmoden und Bestimmung der Schwingbeanspruchungen im integralen Turbinenrad erarbeitet. Das Modell wird auf vorhandene Turbinenräder angewendet und aus den Ergebnissen werden Hinweise für eine systematische Beurteilung der Schaufelmoden, Knotendurchmesser und Schaufelgestaltung bezüglich der kritischen Schwingbeanspruchungen angegeben.
Desweiteren wird der Einfluss der Verstimmung (engl. Mistuning) des Schwingverhaltens realer, integraler Turbinenräder ausführlich im Hinblick auf die Schwingbeanspruchungen untersucht. Die wesentlichen Ursachen für die Verstimmung sind die innerhalb der Fertigungstoleranzen auftretenden Geometrieabweichungen der Schaufeln. Dabei wird ein Überblick über die typischen Geometrie- und Frequenzabweichungen Radialturbinen gegeben und Auswirkungen auf das Schwingverhalten des Rades wie Lokalisierung der Schwingformen und Amplitudenüberhöhungen ermittelt und in einen systematischen Zusammenhang mit den geometrischen Ursachen, der Komplexität der Schaufelschwingformen und Knotendurchmesser gestellt. Es zeigt sich, dass unter gewissen Voraussetzungen bei Radialturbinen KD0 und KD1 Schwingformen weniger sensibel auf die Verstimmung reagieren. Hieraus können Hinweise für die Verbesserung des Auslegungsprozess abgeleitet werden.
Die Kenntnis über das reale Schwingverhalten verstimmter Turbinenräder ermöglicht die korrekte Auswahl geeigneter Schaufeln zur Applikation von Dehnmessstreifen, wodurch eine sichere Beurteilung der Betriebsbeanspruchungen erst möglich wird.