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Статті в журналах з теми "Bladed Disks Dynamic"
1
Zhao, Zhi Bin, Er Ming He, and Hong Jian Wang. "Experimental Investigation on Natural Characteristics and Forced Response of Bladed Disks." Applied Mechanics and Materials 105-107 (September 2011): 34–37. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.34.
Повний текст джерелаАнотація:
The results of an experimental investigations on the natural characteristics of tuned bladed disk and forced dynamic responses of mistuned bladed disks are reported. Three experimental bladed disks are discussed: a tuned specimen of periodic symmetry with 12-blades which are nominally identical, and two mistuned specimens, which feature small blade-to-blade variations by adding slight blocks to blade tips. All the specimens are subject to travelling wave excitation produced by piezo-electric actuators sticking on the root of blades. The primary objective of this experiment is to observe the natural characteristics of tuned bladed disk, and to research the impact of mistuning on the forced response blade amplitude magnification. Analytical predictions about the blade amplitude magnification factor are verified by the experimental results.
2
Judge, J., C. Pierre, and O. Mehmed. "Experimental Investigation of Mode Localization and Forced Response Amplitude Magnification for a Mistuned Bladed Disk." Journal of Engineering for Gas Turbines and Power 123, no. 4 (October 1, 2000): 940–50. http://dx.doi.org/10.1115/1.1377872.
Повний текст джерелаАнотація:
The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. The primary aim of the experiment is to gain understanding of the phenomena of mode localization and forced response blade amplitude magnification in bladed disks. A stationary, nominally periodic, 12-bladed disk with simple geometry is subjected to a traveling-wave out-of-plane “engine order” excitation delivered via phase-shifted control signals sent to piezoelectric actuators mounted on the blades. The bladed disk is then mistuned by the addition of small, unequal weights to the blade tips, and it is again subjected to a traveling wave excitation. The experimental data is used to verify analytical predictions about the occurrence of localized mode shapes, increases in forced response amplitude, and changes in resonant frequency due to the presence of mistuning. Very good agreement between experimental measurements and finite element analysis is obtained. The out-of-plane response is compared and contrasted with the previously reported in-plane mode localization behavior of the same test specimen. This work also represents an important extension of previous experimental study by investigating a frequency regime in which modal density is lower but disk-blade interaction is significantly greater.
3
Bladh, R., M. P. Castanier, and C. Pierre. "Component-Mode-Based Reduced Order Modeling Techniques for Mistuned Bladed Disks—Part I: Theoretical Models." Journal of Engineering for Gas Turbines and Power 123, no. 1 (April 2, 2000): 89–99. http://dx.doi.org/10.1115/1.1338947.
Повний текст джерелаАнотація:
Component mode synthesis (CMS) techniques are widely used for dynamic analyses of complex structures. Significant computational savings can be achieved by using CMS, since a modal analysis is performed on each component structure (substructure). Mistuned bladed disks are a class of structures for which CMS is well suited. In the context of blade mistuning, it is convenient to view the blades as individual components, while the entire disk may be treated as a single component. Individual blade mistuning may then be incorporated into the CMS model in a straightforward manner. In this paper, the Craig–Bampton (CB) method of CMS is formulated specifically for mistuned bladed disks, using a cyclic disk description. Then a novel secondary modal analysis reduction technique (SMART) is presented: a secondary modal analysis is performed on a CB model, yielding significant further reduction in model size. In addition, a straightforward non-CMS method is developed in which the blade mistuning is projected onto the tuned system modes. Though similar approaches have been reported previously, here it is generalized to a form that is more useful in practical applications. The theoretical models are discussed and compared from both computational and practical perspectives. It is concluded that using SMART, based on a CB model, has tremendous potential for highly efficient, accurate modeling of the vibration of mistuned bladed disks.
4
Carassale, Luigi, and Elena Rizzetto. "Experimental Investigation on a Bladed Disk with Traveling Wave Excitation." Sensors 21, no. 12 (June 8, 2021): 3966. http://dx.doi.org/10.3390/s21123966.
Повний текст джерелаАнотація:
Bladed disks are key components of turbomachines and their dynamic behavior is strongly conditioned by their small accidental lack of symmetry referred to as blade mistuning. The experimental identification of mistuned disks is complicated due to several reasons related both to measurement and data processing issues. This paper describes the realization of a test rig designed to investigate the behavior of mistuned disks and develop or validate data processing techniques for system identification. To simplify experiments, using the opposite than in the real situation, the disk is fixed, while the excitation is rotating. The response measured during an experiment carried out in the resonance-crossing condition is used to compare three alternative techniques to estimate the frequency-response function of the disk.
5
Gao, Shimin, Yanrong Wang, Zhiwei Sun, and Siyuan Chen. "A Prediction Method with Altering Equivalent Stiffness for Damping Evaluation of Shrouded Bladed Disk Dynamic Systems." Symmetry 13, no. 3 (March 4, 2021): 413. http://dx.doi.org/10.3390/sym13030413.
Повний текст джерелаАнотація:
In turbomachinery bladed disks are typical cyclic symmetric structures where high-cycle fatigue of the blades can easily occur. Increasing the shroud structure is an effective blade vibration reduction method using the dry friction of the shroud contact surface to dissipate vibration energy. During one vibration cycle of the blade, the contact surface of the shroud may have one or several states of stick, slip, and separation due to the different amplitude of blade, which affects not only the damping, but also the stiffness of the system. This paper proposes a method to analyze the damping characteristics of blades with shroud considering the change of equivalent contact stiffness of the shroud by using the finite element method. With a 2D contact model, this method calculates the equivalent damping and obtains the damping characteristic curve to evaluate the damping of shroud. During the design phase, the objective is that when resonance occurs, the shroud can provide the optimal damping ratio under the allowable vibration stress of the blade. The parameter sensitivity of the damping characteristic for one bladed disk with parallel shroud is investigated. It is shown that vibration phase angle, contact stiffness, contact force, friction coefficient significantly influence the damping characteristics.
6
Mignolet, M. P., A. J. Rivas-Guerra, and J. P. Delor. "Identification of Mistuning Characteristics of Bladed Disks From Free Response Data—Part I." Journal of Engineering for Gas Turbines and Power 123, no. 2 (June 9, 1999): 395–403. http://dx.doi.org/10.1115/1.1338949.
Повний текст джерелаАнотація:
The focus of the present two-part investigation is on the estimation of the dynamic properties, i.e., masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example, in a broach block test. Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. In this first part of the investigation, two distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to ensure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade to blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function.” The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
7
Sommariva, Alessandro, and Stefano Zucca. "A Comparison between Two Reduction Strategies for Shrouded Bladed Disks." Applied Sciences 8, no. 10 (September 26, 2018): 1736. http://dx.doi.org/10.3390/app8101736.
Повний текст джерелаАнотація:
Shrouded bladed disks exhibit a nonlinear dynamic behavior due to the contact interfaces at shrouds between neighboring blades. As a result, reduced order models (ROMs) are mandatory to compute the response levels during the design phase for high cycle fatigue (HCF) life assessment. In this paper, two reduction strategies for shrouded bladed disk reduction are presented. Both approaches rely on: (i) the cyclic symmetry of the linear bladed disk with open shrouds to perform only single sector calculations, (ii) the Craig–Bampton (CB) method to reduce the number of physical degrees of freedom (dofs). The two approaches are applied to a set of test cases in order to evaluate and compare their accuracy and the associated computational effort. Although both approaches allow for generating accurate ROMs, it is found that the numerical efficiency of the two methods depends on the ratio of the number of nodes at the inter-sector interfaces over the number of inner nodes of the elementary sector model.
8
Moraga, Greco, Mònica Egusquiza, David Valentín, Carme Valero, and Alexandre Presas. "Analysis of the Mode Shapes of Kaplan Runners." Applied Sciences 12, no. 13 (July 2, 2022): 6708. http://dx.doi.org/10.3390/app12136708.
Повний текст джерелаАнотація:
To prevent lifetime shortening and premature failure in turbine runners, it is of paramount importance to analyse and understand its dynamic response and determine the factors that affect it. In this paper, the dynamic response of a Kaplan runner is analysed in air by numerical and experimental methods. First, to start the analysis of Kaplan runner mode shapes, its geometry is simplified and modelled as a bladed disk. Bladed disks with different blade numbers are investigated, by numerical simulation, in order to understand the influence of this parameter on its modal characteristics. Then, mode shapes extracted are characterized and a classification is proposed. Second, an existing Kaplan runner is simulated by Finite Elements Method (FEM) and its mode shapes are extracted. The obtained results are contrasted with the bladed disks mode shapes, in order to validate the classification proposed. The simulated Kaplan runner is also experimentally studied. A numerical modal analysis is carried out in the real runner. Different, global and local, mode shapes are identified. The global mode shapes extracted by numerical and experimental modal analysis are compared and discussed. Finally, the local mode shapes identified are commented and explained by means of numerical simulation.
9
Flowers, G. T., and Fang Sheng Wu. "A Study of the Influence of Bearing Clearance on Lateral Coupled Shaft/Disk Rotordynamics." Journal of Engineering for Gas Turbines and Power 115, no. 2 (April 1, 1993): 279–86. http://dx.doi.org/10.1115/1.2906706.
Повний текст джерелаАнотація:
This study examines the influence of bearing clearance on the dynamic behavior of a rotating, flexible disk/shaft system. Most previous work in nonlinear rotordynamics has tended to concentrate separately on shaft vibration or on bladed disk vibration, neglecting the coupling dynamics between them. The current work examines the important rotordynamic behavior of coupled disk/shaft dynamics. A simplified nonlinear model is developed for lateral vibration of a rotor system with a bearing clearance nonlinearity. The steady-state dynamic behavior of this system is explored using numerical simulation and limit cycle analysis. It is demonstrated that bearing clearance effects can produce superharmonic vibration that may serve to excite high-amplitude disk vibration. Such vibration could lead to significantly increased bearing loads and catastrophic failure of blades and disks. In addition, multivalued responses and aperiodic behavior were observed.
10
Petrov, E. P., and D. J. Ewins. "Advanced Modeling of Underplatform Friction Dampers for Analysis of Bladed Disk Vibration." Journal of Turbomachinery 129, no. 1 (February 1, 2006): 143–50. http://dx.doi.org/10.1115/1.2372775.
Повний текст джерелаАнотація:
Advanced structural dynamic models for both wedge and split underplatform dampers have been developed. The new damper models take into account inertia forces and the effects of normal load variation on stick-slip transitions at the contact interfaces. The damper models are formulated for the general case of multiharmonic forced response analysis. An approach for using the new damper models in the dynamic analysis of large-scale finite element models of bladed disks is proposed and realized. Numerical investigations of bladed disks are performed to demonstrate the capabilities of the new models and an analysis of the influence of the damper parameters on the forced response of bladed disks is made.
Дисертації з теми "Bladed Disks Dynamic"
1
Bah, Mamadou Tahirou. "Reduced order modelling for efficient prediction of the dynamics of mistuned bladed disks." Thesis, University of Southampton, 2002. https://eprints.soton.ac.uk/45931/.
Повний текст джерелаАнотація:
The unavoidable existence of small differences between nominally identical sectors of bladed disks, called mistuning, can have an important impact on the dynamic behaviour of these structures. In particular, this has the potential to lead to responses qualitatively different from that of an ideal cyclic, tuned structure and, in turn, to significantly shorter life spans. Study of mistuning as a random phenomenon requires statistical analysis of a large number of mistuning patterns. This computational task is expensive especially when high-fidelity finite element models are used. This research is concerned with the development of reduced order computational modelling techniques for the dynamic analysis of mistuned bladed disks. These techniques combine accuracy and computational efficiency for a reliable statistical assessment of the effects of mistuning on the dynamics of such systems. For free vibration, the nominal assessment of the effects of mistuning on the dynamics of such systems. For free vibration, the nominal periodicity is exploited, leading to an approximation that greatly reduces the order of the original model. The natural frequencies and mode shapes for a passband are found by treating the unknown complex amplitudes between the nominally identical sectors as the generalized co-ordinates of the problem. In spite of a very large reduction in the computational effort, the results obtained are very accurate both for frequencies and mode shapes even when strong mode localization is observed. To test the perfor4mance of the proposed approximation further, a situation where two passbands are brought close to each other is also considered. This method is general in its formulation and has the potential of being used for complex geometries. It is also extended to the frequency response problem. The great advantage is that the statistics of ‘blades’ forced responses can be numerically generated at a cost of a single degree-of-freedom per blade/disk sector model. Furthermore, a stochastic reduced basis approach is developed for the approximation of these statistics. This approach allows for a complete stochastic analysis of the effects of mistuning. The system response is represented using a linear combination of complex stochastic basis vectors with undetermined coefficients. The terms of the preconditioned stochastic Krylov subspace are used as basis vectors. Two variants of the stochastic Bubnov-Galerkin scheme are employed for computing the undetermined terms in the reduced basis representation. Explicit expressions for the response quantities are then derived in terms of the system random parameters. This allows for the possibility of efficiently computing the response statistics in the post-processing stage. This novel approach can be applied either on the original model in the physical domain or on a reduced model in the modal domain as a secondary reduction technique. The accuracy of the response statistical moments computed using this approach can be orders of magnitude better than classical perturbation methods. Finally, component mode synthesis or substructuring and probabilistic methods are combined to generate reduced order models. The Craig-Bampton reduction procedure is applied while using stochastic component modes instead of deterministic modes. An additional calculation of sensitivities of fixed interface modes, constraint modes and substructure-matrices is required with respect to the physical random variables. In the case of turbomachinery mistuned bladed disks composed of nearly identical substructures, the sensitivity analysis can be targeted to only one substructure. One great advantage is that the physical variations can be used as input in the reduced order model. This novel approach allows for an efficient computation of the statistical characteristics of responses and a complete stochastic analysis of the effects of mistuning.
2
Fang, Chih. "A reduced-order meshless energy (ROME) model for the elastodynamics of mistuned bladed disks." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12457.
Повний текст джерела
3
Yumer, Mehmet Ersin. "On The Non-linear Vibration And Mistuning Identification Of Bladed Disks." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611498/index.pdf.
Повний текст джерелаАнотація:
Forced response analysis of bladed disk assemblies plays a vital role in rotor blade design and has been drawing a great deal of attention both from research community and engine industry for more than half a century. However because of the phenomenon called &lsquomistuning&rsquo
, which destroys the cyclic symmetry of a rotor, there have been several difficulties related to forced response analysis ever since, two of which are addressed in this thesis: efficient non-linear forced response analysis of mistuned bladed disks and mistuning identification. On the nonlinear analysis side, a new solution approach is proposed studying the combined effect of non-linearity and mistuning, which is relatively recent in this research area and generally conducted with methods whose convergence and accuracy depend highly on the number of degrees of freedom where non-linear elements are attached. The proposed approach predicts nonlinear forced response of mistuned bladed disk assemblies considering any type of nonlinearity. In this thesis, special attention is given to the friction contact modeling of bladed disks which is the most common type of nonlinearity found in bladed disk assemblies. In the modeling of frictional contact a friction element which enables normal load variation and separation of the contact interface in three-dimensional space is utilized. Moreover, the analysis is carried out in modal domain where the differential equations of motions are converted to a set of non-linear algebraic equations using harmonic balance method and modal superposition technique. Thus, the number of non-linear equations to be solved is independent of the number of non-linear elements used. On the mistuning identification side, a new method is enclosed herein which makes use of neural networks to assess unknown mistuning parameters of a given bladed disk assembly from its assembly modes, thus being suitable for integrally bladed disks. The method assumes that a tuned mathematical model of the rotor under consideration is readily available, which is always the case for today&rsquo
s realistic bladed disk assemblies. A data set of selected mode shapes and natural frequencies is created by a number of simulations performed by mistuning the tuned mathematical model randomly. A neural network created by considering the number of modes, is then trained with this data set for being used to identify mistuning of the rotor from measured data. On top of these, a new adaptive algorithm is developed for harmonic balance method, several intentional mistuning patterns are investigated via excessive Monte-Carlo simulations and a new approach to locate, classify and parametrically identify structural non-linearities is introduced.
4
Sternchüss, Arnaud. "Multi-level parametric reduced models of rotating bladed disk assemblies." Phd thesis, Ecole Centrale Paris, 2009. http://tel.archives-ouvertes.fr/tel-00366252.
Повний текст джерелаАнотація:
Les disques aubagés, que l'on trouve dans les turbomachines, sont des structures complexes dont le comportement vibratoire est généralement déterminé par l'exploitation de conditions de symétrie dans leur configuration nominale. Cette symétrie disparaît lorsque l'on assemble plusieurs de ces disques pour former un rotor ou que l'on introduit une variabilité spatiale des paramètres mécaniques (on parle de désaccordage intentionnel ou non). Le raffinement des maillages, nécessaire à une évaluation correcte de la répartition des contraintes, conduirait à des modèles de rotor complet de taille prohibitive (plusieurs dizaines de millions de degrés de liberté). L'objectif de cette thèse est donc l'introduction de méthodologies de réduction qui par combinaison de calculs acceptables permettent d'étudier de façon fine la dynamique d'ensemble sur des modèles 3D fins multi-étages et potentiellement désaccordés. L'étude des transformations de Fourier séparées des réponses de chaque étage permet, dans un premier temps, de bien comprendre les effets de couplage inter-harmonique liés au couplage inter-disque et au désaccordage. A partir de ce constat, une première méthode utilise les résultats de calculs en symétrie cyclique et à secteur encastré pour construire un modèle de secteur exact pour certains modes dits cibles et de très bonne qualité pour les autres modes. Cette méthode est ensuite étendue au cas multi-étage en construisant des bases de réduction de secteur par combinaison de solutions mono-harmoniques. Les illustrations montrent que la méthodologie proposée permet le traitement de modèles de très grande taille, tout en restant compatible avec une grande richesse de post-traitements (calculs de modes, calculs de réponses forcées, analyses de leur contenu harmonique spatial, répartition d'énergie et effets de localisation...). La méthodologie est enfin étendue à la gestion de modèles paramétrés en vitesse de rotation. L'enrichissement des ensembles de modes cibles par des calculs à trois vitesses permet ainsi une reconstruction rapide de l'évolution des fréquences pour l'ensemble d'un intervalle.
5
Picou, Anthony. "Robust analysis under uncertainties of bladed disk vibration with geometrical nonlinearities and detuning." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2038.
Повний текст джерелаАнотація:
Le désaccordage intentionnel, plus communément appelé detuning, a été identifié comme une possible technonologie pour réduire la sensibilité du comportement dynamique de roues aubagées soumises au désaccordage involontaire, aussi appelé mistuning, causé par les dispersions matérielle d'une aube à une autre engendrées lors du processus de fabrication et par la variabilité des propriétés mécaniques des matériaux. Le désaccordage intentionnel est mis en place par l'introduction de motifs à partir desquels différents types de secteurs générateurs, ayant des propriétés géométriques et matérielles différentes, sont assemblés. Cependant, les récentes innovations technologiques impliquant l'utilisation d'aubes de plus en plus flexibles et plus légères conduisent à de grands niveaux de déplacements et de déformations, requiérant l'utilisation des équations dynamiques non linéaires tenant compte des non-linéarités géométriques. Ce travail est dédié à l'analyse robuste des effets des non-linéarités géométriques sur la dynamique non linéaire de roues aubagées désacccordées intentionnellement, en rotation, en présence de désaccordage involontaire. Le désaccordage involontaire correspond à des incertitudes dans le modèle numériques et sont prises en compte par une approche probabiliste. Cette thèse de nouveaux résultats concernant la dynamique non linéaire des roues aubagées désaccordées intentionnellement en présense de non-linéarités géométriques et en présence de désaccordage involontaire. Les analyses dynamiques sont effectuées dans le domaine temporel et analysées dans le domaine fréquentiel. L'analyse fréquentielle des réponses non-linéaires mettent en évidence des réponses significatives en dehors de la bande d'excitation. Les intervalles de confiance des réponses stochastiques permettent d'analyser la robustesse du modèle vis-à-vis des incertitudes, c'est-à-dire du niveau de désaccordage involontaire. La roue aubagées utilisée pour les simulations numériques est composée de 24 secteurs pour lesquels différents motifs de roues aubagées désaccordées intentionnellement sont analysés, avec ou sans désaccordage involontaireThe intentional mistuning, also called detuning has been identified as an efficient technological way for reducing the sensitivity of the forced response of bladed disks to unintentional mistuning (simply called mistuning), caused by the manufacturing tolerances and the small variations in the mechanical properties from blade to blade. The intentional mistuning consists in detuning the bladed disk structure by using partial or alternating patterns of different sector types. However, the recent technological improvements that include the use of more flexible and lighter blades can lead to large strains/displacements, which requires the use of nonlinear dynamic equations involving geometric nonlinearities. This work is devoted to the robust analysis of the effects of geometric nonlinearities on the nonlinear dynamic behavior of rotating detuned bladed disks in presence of mistuning. The detuning corresponds to uncertainties in the computational model, and are taken into account by a probabilistic approach. This thesis presents a series of novel results in dynamics of rotating bladed disks with mistuning and detuning in presence of nonlinear geometrical effects. The structural responses are computed in the time domain and are analyzed in the frequency domain. The frequency analysis exhibits responses outside the frequency band of excitation. The confidence region of the stochastic responses allows the robustness to be analyzed with respect to uncertainties, that is to say with respect to the level of mistuning. The bladed disk structure, which is used for the numerical simulations, is made up of 24 blades for which several different detuned patterns are investigated with and without mistuning
6
Shankare, Gowda Vrishank Raghav. "Radial flow effects on a retreating rotor blade." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53403.
Повний текст джерелаАнотація:
This work studies the effects of radial flow on the aerodynamic phenomena occurring on a retreating blade with a focus on dynamic stall and reverse flow as applied to both a helicopter rotor in forward flight and a wind turbine operating at a yaw angle. While great progress has been made in understanding the phenomenon of two-dimensional dynamic stall, the effect of rotation on the dynamic stall event is not well understood. Experiments were conducted on a rigid two bladed teetering rotor at high advance ratios in a low speed wind tunnel. Particle image velocimetry (PIV) measurements were used to quantify the flow field at several azimuthal angles on the rotating blade during the dynamic stall event. The effect of centrifugal forces induced ``pure'' radial velocity on the dynamic stall event at 270 degrees azimuth was studied in detail. Further investigation of the radial flow field suggested that the mean radial velocity attenuated on moving outboard due to an apparent shear layer instability and it was demonstrated to be of first order importance in the flow field. These radial flow results prompted an exploration of the flow over a rotating disk to establish similarities of the radial flow over rotating blade in separated flow to that over a rotating disk in separated flow. While a greater part of this work focused on aspects of dynamic stall on the retreating blade, the final parts focus on the exotic flow regime of reverse flow (characterized by flow from the trailing edge to the leading edge of the blade). Aerodynamic loads measurement and surface flow visualization via tufts are used to first quantify the behavior of a static yawed blade in reverse flow. PIV measurements are then used on a static yawed blade and a rotating blade in reverse flow conditions to ascertain the effects of rotation on reverse flow.
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Dumartineix, Cécile. "Modélisation et étude de la dynamique complexe d'un système bi-rotor aubagé couplé." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEC049.
Повний текст джерелаАнотація:
L'optimisation des turboréacteurs nécessite une excellente maîtrise des phénomènes vibratoires de la structure complète et notamment des interactions entre les différents organes constitutifs du moteur. Dans le cas d'une ligne d'arbre, le couplage entre dynamique d'ensemble et dynamique d'aubages modifie le comportement des roues aubagées, généralement dimensionnées individuellement. La prise en compte de ce phénomène fait intervenir des modèles de grandes tailles, justifiant la nécessité de développer des outils numériques spécifiques intégrant une stratégie de résolution peu coûteuse. Ces échanges énergétiques sont d'autant plus difficiles à prévoir pour une architecture bi-rotor possédant un palier inter-arbre: lors de la mise en équation simultanée des deux rotors, leur différence de vitesse de rotation génère des coefficients périodiques problématiques, impliquant une résolution temporelle onéreuse. L'objet principal de ce mémoire de thèse consiste à développer une nouvelle méthode de projection de l'équation du mouvement d'un bi-rotor aubagé, dans le but de se ramener à une forme traditionnelle d'équation permettant d'appliquer les méthodes de résolution fréquentielles classiques. La validation par comparaison avec une résolution temporelle de référence donne d'excellents résultats sur des modèles éléments finis simples soumis à des excitations mono- et multi- fréquentielles. Le gain notable en temps de calcul permet d'exploiter la méthode pour étudier, sur de larges plages de vitesse, la réponse forcée d'un système caractéristique de deux roues aubagées couplées. Deux phénomènes d'interaction vibratoire notables sont ainsi mis en évidence, traduisant des échanges énergétiques au travers du palier inter-arbre. Une détection graphique des zones d'instabilité en fonction des deux vitesses de rotation est également établie puis validée à l'aide de formulations bi-anneau. Par la suite, la méthode de projection de l'équation du mouvement est étendue à deux problématiques industrielles actuelles. Dans le cas où une non-linéarité de frottement est présente sur l'une des roues aubagées, une adaptation de la méthode de résolution non-linéaire par équilibrage harmonique est proposée afin de traiter la forme d'équation obtenue après projection. L'influence de la nature du couplage est finalement abordée en remplaçant le palier inter-arbre par un réducteur à engrenagesTurbomachines optimization requires an excellent control of the vibration phenomena of the whole structure, especially in regards to the interactions between the different parts of the engine. The coupling between global dynamics and blade dynamics of a shaft line alters the vibration behavior of the bladed-disks, which are usually designed separately. The study of these phenomena comes with large sized models which require specific numerical tools with low-cost solving strategy. These energy exchanges are particularly difficult to predict in the case of a bi-rotor architecture coupled with a bearing system. When the equations of motion of both structures are written simultaneously, the rotating speed difference introduces time-periodic coefficients which yield expensive time resolution. The main purpose of this thesis is to develop a new methodology for the projection of the equation of motion of a bladed bi-rotor system in order to restore a regular equation form compatible with classical frequency solving methods. Compared with time resolution taken as reference, this new approach gives accurate results when applied on simple finite element models submitted to mono- and multi-frequency excitation forces. This substantially time-saving method makes it possible to study the forced response of a characteristic system of two coupled bladed-disks, on a large range of rotation speeds. Two vibratory interaction phenomena are thus revealed, directly related to the occurrence of energy exchanges through the inter-shaft bearing. A graphic detection of unstable areas according to both rotation speeds is established and validated thanks to a double ring model. The proposed projection methodology of the equation of motion is then extended to consider two current industrial challenges. First, in the case of friction nonlinearity present on one bladed-disk, the harmonic balance method is adapted to fit the new form of equation obtained after projection. Finally, the impact of the coupling mechanism is studied by replacing the bearing with a gearbox
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Salles, Loïc. "Etude de l'usure par fretting sous chargements dynamiques dans les interfaces frottantes : application aux pieds d'aubes de turbomachines." Phd thesis, Ecole Centrale de Lyon, 2010. http://tel.archives-ouvertes.fr/tel-00600613.
Повний текст джерелаАнотація:
Les parties tournantes des turbomachines aéronautiques sont composées d'une succession de roues aubagées qui permettent le transfert de l'énergie entre l'air et le rotor. Ces roues aubagées constituent des pièces particulièrement sensibles car elles doivent répondre en termes de dimensionnement à des impératifs de performances aérodynamiques, d'aéroacoustique et de tenue mécanique à la rotation,à la température et à la charge aérodynamique. Le contact avec frottement existant au niveau des attaches aube-disque joue un rôle important sur les niveaux vibratoires.Ce travail porte sur l'étude de l'usure par fretting sous chargements dynamiques dans les interfaces frottantes. En effet, les vibrations de l'aube peuvent produire des micro-glissements en pied d'aubequi peuvent entraîner un phénomène d'usure par fretting. Les connaissances sur le comportement de l'usure sous sollicitations dynamiques sont faibles. Seuls existent des outils numériques pour modéliser l'usure dans le cas de sollicitations quasi-statiques. Nous proposons dans cette thèse des méthodes pour calculer l'évolution de l'usure au cours des cycles de chargement dynamique basées sur une approche multi-échelle en temps. La réponse vibratoire de la structure est liée à une échelle de temps rapide qui est calculée par une méthode d'équilibrage harmonique, dans laquelle les déplacements et les efforts sont projetés sur la base de Fourier. Différentes approches temps-fréquence de calcul des coefficients de Fourier des forces de contact sont présentées. La cinétique d'usure est liée à une échelle lente et différentes méthodes sont proposées pour l'intégrer. La prise en compte des géométries usées dans le modèle éléments finis se fait par l'ajout d'un vecteur des profondeurs d'usure dans le terme de pénalité des lagrangiens dynamiques. Des exemples académiques valident et illustrent les méthodes proposées. Ces méthodes sont ensuite appliquées à l'étude de l'usure par fretting en pied d'aube de soufflante. L'étude numérique met en lumière le couplage entre vibration et usure par fretting aux interfaces de contact. La modification du comportement dynamique global de la roue aubagée est aussi observée.
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Óttarsson, Gísli. "Dynamic modeling and vibration analysis of mistuned bladed disks." Phd thesis, 1994. http://tel.archives-ouvertes.fr/tel-00598068.
Повний текст джерелаАнотація:
One of the most important problems that plague turbomachinery rotors is the existence of rogue blades -- lone blades that exhibit unexpected fatigue failure. It has been recognized that rotor mistuning might be the cause of rogue blades through a phenomenoncalled normal mode localization, whereby vibration energy is confined to a few blades of the assembly. The goals of this dissertation are (1) to achieve a thorough understanding of the fundamental mechanisms governing mistuning effects, (2) the development of mathematical models of turbomachinery rotors suitable for mistuning analysis, and (3) the development of techniques for designers interested in the mistuning sensitivity of a particular rotor design.
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Cheng, Wen-Yuan, and 鄭文源. "Dynamic Modeling of Bladed-Disks Using Pseudo Mode Shape Method." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/71562129059071766246.
Повний текст джерелаАнотація:
碩士元智大學
機械工程學系
95
Vibration coupling occurs between bladed disks and shafts in high-speed rotors of large steam turbine-generators. Therefore, the effects of bladed disks on the shafts can not be neglected. If solid elements are used in the finite element modeling of multiple-bladed-disk rotors, problems of huge amount of elements and time consuming in computation often make simulation and analysis impractical. Model reduction is necessary to reduce the size of the matrices of substructures for computation. On the other hand, both limited test points in setting the measurement hardware, caused by the complicated configuration of the structure, and lack of test time during maintenance or overhauling result in incomplete mode shape information. Only a few frequency response functions of the systems are difficult to convert the modal models to the matrices of spatial models. A desire for methods to operate under the situation of incomplete mode shape information arises. A modified pseudo mode shape method was proposed to reduce the models of bladed-disks in this thesis. The frequency response functions of bladed-disks obtained at the joints with the shafts are used to derive the condensed mass, damping, and stiffness matrices for the substructures. This thesis extends the theory of pseudo mode shape method developed previously to include rigid body modes and deformation modes of the substructures. The extended theory can cover wider frequency ranges and more modes of bladed disks and the derived matrices are easily incorporated into the existing programs of rotordynamics to perform the analyses of rotor-bladed disks systems. The feasibility and effectiveness of the extended pseudo mode shape method are justified by three examples: (1) 2-D cantilevered beam (b) beam-typed shaft and solid-modeled bladed disk and (3) solid-modeled shaft and bladed disk.
Книги з теми "Bladed Disks Dynamic"
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V, Nagpal, Chamis C. C, and United States. National Aeronautics and Space Administration., eds. Probabilistic analysis of bladed turbine disks and the effect of mistuning. [Washington, D.C: National Aeronautics and Space Administration, 1990.
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Center, Lewis Research, ed. Parallel processing for nonlinear dynamics simulations of structures including rotating bladed-disk assemblies: Report to NASA Lewis Research Center. Ithaca, N.Y: School of Civil and Environmental Engineering and Program of Computer Graphics, Cornell University, 1993.
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J, Maffeo Robert, Schwartz S, and United States. National Aeronautics and Space Administration., eds. Engine structures analysis software: Component specific modeling (COSMO). [Washington, D.C.]: National Aeronautics and Space Administration, 1994.
Знайти повний текст джерелаЧастини книг з теми "Bladed Disks Dynamic"
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Kaneko, Yasutomo, Kazushi Mori, and Hiroharu Ooyama. "Vibration Response Analysis of Mistuned Bladed Disk Consisting of Directionally Solidified Blade." In Proceedings of the 9th IFToMM International Conference on Rotor Dynamics, 101–11. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-06590-8_9.
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Carassale, Luigi, Mirko Maurici, and Laura Traversone. "Reduced-Order Modeling of Turbine Bladed Discs by 1D Elements." In Special Topics in Structural Dynamics, Volume 6, 133–43. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15048-2_13.
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Carassale, Luigi, Andrea Bessone, and Andrea Cavicchi. "Interface Reduction in Component Mode Synthesis of Bladed Disks by Orthogonal-Polynomial Series." In Dynamics of Coupled Structures, Volume 4, 201–4. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-74654-8_17.
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Ewins, D. J., and Y. J. Chan. "Vibration of Rotating Bladed Discs: Mistuning, Coriolis, and Robust Design." In IUTAM Symposium on Emerging Trends in Rotor Dynamics, 163–75. Dordrecht: Springer Netherlands, 2010. http://dx.doi.org/10.1007/978-94-007-0020-8_15.
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Rzadkowski, Romuald, Artur Maurin, and Ryszard Szczepanik. "Forced Vibration of Eight Mistuned Bladed Discs on a Solid Shaft—Excitation of the Second Compressor Bladed Disc." In Proceedings of the 9th IFToMM International Conference on Rotor Dynamics, 89–100. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-06590-8_8.
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Ma, Hui, Zhiyuan Wu, Xingyu Tai, Chaofeng Li, and Bangchun Wen. "Nonlinear Behavior Analysis Caused by Blade Tip Rubbing in a Rotor-Disk-Blade System." In Proceedings of the 9th IFToMM International Conference on Rotor Dynamics, 181–91. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-06590-8_15.
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Pešek, Luděk, Pavel Šnábl, Petr Šulc, Ladislav Půst, and Vítězslav Bula. "3D FE modelling of non-linear dynamics of bladed model disk with dry-friction contacts in tie-bosses." In Advances in Mechanism and Machine Science, 3429–38. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-20131-9_338.
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Nikolaev, Evgeny, and Maria Nikolaeva. "Discrete Vortex Cylinders Method for Calculating the Helicopter Rotor-Induced Velocity." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93186.
Повний текст джерелаАнотація:
A new vortex model of a helicopter rotor with an infinite number of blades is proposed, based on Shaidakov’s linear disk theory for calculating inductive speeds at any point in space in the helicopter area. It is proposed to consider the helicopter rotor and the behind vortex column as a system of discrete vortex cylinders. This allows building a matrix of the influence of the vortex system under consideration on any set of points, for example, the calculated points on the rotor itself, on the tail rotor, etc. The model allows calculating inductive velocities at any point near the helicopter using matrix multiplication operation. It is shown that the classical results for the momentum theory remain constant even in the discrete simulation of the helicopter rotor vortex system. The structure of the air flow behind the rotor and the simulation results obtained by the proposed method is compared with the structure of the tip vortices and the results of the blade vortex theory. In addition, the experimental data were compared with the simulation results to verify the correctness of the model under real operating conditions by the helicopter trimming.
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Maria, Christian, and Stefano Zucc. "Modelling Friction Contacts in Structural Dynamics and its Application to Turbine Bladed Disks." In Numerical Analysis - Theory and Application. InTech, 2011. http://dx.doi.org/10.5772/25128.
Повний текст джерелаТези доповідей конференцій з теми "Bladed Disks Dynamic"
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Kruse, Marlin J., and Christophe Pierre. "An Experimental Investigation of Vibration Localization in Bladed Disks: Part II — Forced Response." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-502.
Повний текст джерелаАнотація:
The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. Two experimental specimens are considered: a nominally periodic twelve-bladed disk with equal blade lengths, and the corresponding mistuned bladed disk, which features slightly different blades of random lengths. Both specimens are subject to traveling-wave excitations delivered by piezo-electric actuators. The primary aim of the experiment is to demonstrate the occurrence of an increase in forced response blade amplitudes due to mistuning, and to verify analytical predictions about the magnitude of these increases. In particular, the impact of localized mode shapes, engine order excitation, and disk structural coupling on the sensitivity of forced response amplitudes to blade mistuning is reported. This work reports one of the first systematic experiments carried out to demonstrate and quantify the effect of mistuning on the forced response of bladed disks.
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Salles, Loi¨c, Alexander M. Gouskov, Laurent Blanc, Fabrice Thouverez, and Pierrick Jean. "Dynamic Analysis of Fretting-Wear in Joint Interface by a Multiscale Harmonic Balance Method Coupled With Explicit or Implicit Integration Schemes." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23264.
Повний текст джерелаАнотація:
Assembled bladed disks have many contact interfaces (blade-disk joint, blade shrouds, friction damper, etc). Because of relative displacements at these interfaces, fretting-wear can occur, which shortens the life expectancy of the structure. Moreover, vibrations that occur in bladed-disks can increase this fretting-wear phenomenon. Two previous papers in Turboexpo have introduced a numerical method based on the Dynamical Lagrangian Frequency Time algorithm (DLFT) to calculate worn geometry, especially wear of bladed-disks’ dovetail roots. Numerical investigations have illustrated the performances of this method and shown the coupling between dynamical and tribological phenomena. The basic idea of the DLFT-with-wear method is to separate time in two scales, slow scale for tribological phenomena and fast scale for dynamics. In the present paper, implicit and explicit integration schemes on the slow time scale are compared. An ad hoc prediction-correction method is used in both methods to accelerate the convergence of the non-linear solver. Numerical experiments on bladed-disk show that the implicit scheme is more appropriate to deal with fretting-wear under dynamical loading.
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Kruse, Marlin J., and Christophe Pierre. "An Experimental Investigation of Vibration Localization in Bladed Disks: Part I — Free Response." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-501.
Повний текст джерелаАнотація:
The results of an experimental investigation of the effects of random blade mistuning on the free dynamic response of bladed disks are reported. Two experimental specimens are considered: a nominally periodic twelve-bladed disk with equal blade lengths, and the corresponding mistuned bladed disk, which features slightly different, random blade lengths. In the experiment, both the spatially extended modes of the tuned system and the localized modes of the mistuned system are identified. Particular emphasis is placed on the transition to localized mode shapes as the modal density in various frequency regions increases. Excellent qualitative and quantitative agreement is obtained between experimental measurements and results obtained by finite element analysis. Experimental results are additionally used to validate a component mode-based, reduced-order modeling technique for bladed disks. This work reports the first systematic experiment carried out to demonstrate the occurrence of vibration localization in bladed disks.
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Tong, Jing, Chaoping Zang, and E. P. Petrov. "Accurate Interpolation of the Dependency of Modal Properties on the Rotation Speed for the Transient Response Analysis of Bladed Disks." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58982.
Повний текст джерелаАнотація:
Abstract During fast gas-turbine engine acceleration and deceleration the transient vibration effects in bladed disk vibration become significant and the transient response has to be calculated. In this paper an effective method is developed for efficient calculations of the transient vibration response for mistuned bladed disks under varying rotation speeds. The method uses the large-scale finite element modelling of the bladed disks allowing the accurate description of the dynamic properties of the mistuned bladed disks. The effects of the varying rotation speed on the natural frequencies and mode shapes of a mistuned bladed disk and its effects on the amplitude and the spectral composition of the loading are considered. The dependency of the modal characteristics on the rotation speed are based on the evaluation of these characteristics at reference points followed by the interpolation to obtain values at any rotation speed from the operating range. A new method has been developed for the interpolation of mode shapes while preserving the orthogonality and mass-normalization of the mode shapes. The method of mode shape interpolation is elaborated for tuned and mistuned bladed disks. The accuracy and efficiency of the method is demonstrated on test examples and on analysis of transient forced response of realistic bladed discs.
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Beck, Joseph A., Alex A. Kaszynski, Jeffrey M. Brown, Daniel L. Gillaugh, and Onome E. Scott-Emuakpor. "Selection of Dynamic Testing Measurement Locations for Integrally Bladed Disks." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76791.
Повний текст джерелаАнотація:
The selection of sensor locations during dynamic testing of integrally bladed disks (Blisks) is discussed for measuring experimental mode shapes. As-manufactured geometries of the experimental Blisk are obtained in point-cloud form via a structured light optical measurement system. The nominal finite element mesh of the Blisk is then “morphed” to the average sector of as-measured, point-cloud geometry through a mesh metamorphosis algorithm. A ray-tracing algorithm is developed for selecting observable degrees of freedom (DOFs) of the morphed mesh to an overhead laser scanning vibrometer. This set of DOFs is then down-selected since measuring tens-of-thousands of points is in-feasible during experimental testing. This selection is carried out using a Cyclic Effective Independence Method that exploits a Blisk’s cyclic symmetry to greatly reduce computational expenses. Furthermore, the approach allows for selecting points belonging to specific engine order excitations typical in engine operating environments that can be excited during bench top traveling wave testing. Measurement point locations are compared for three cyclic symmetry finite element models: a nominal coarse mesh density, a nominal fine mesh density, and a fine mesh density morphed to average sector geometries.
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Hohl, Andreas, Benedikt Kriegesmann, Jo¨rg Wallaschek, and Lars Panning. "The Influence of Blade Properties on the Forced Response of Mistuned Bladed Disks." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46826.
Повний текст джерелаАнотація:
In turbomachinery applications bladed disks are subjected to high dynamic loads due to fluctuating gas forces. Dynamic excitation can result in high vibration amplitudes which can lead to high cycle fatigue (HCF) failures. Herein, the blades are almost identical but differ due to wear or small manufacturing tolerances. Especially, after regeneration and repair procedures the properties of the blades can differ with a high variance. These deviations of the blade properties can lead to a localization of the vibrational energy in single blades and even higher risk of HCF. A recently developed substructure model with a combination of the Hurty transformation or Component Mode Synthesis (CMS) and the so called Wave Based Substructuring (WBS) is used to obtain a Reduced Order Model (ROM) with a reasonable low number of degrees of freedom. The CMS of the disk can be calculated with one cyclic disk segment of the underlying finite element model. The WBS is used to describe the numerous coupling degrees of freedom between the disk and the blades with a truncated set of waves. The orthogonal waves are derived by a Singular Value Decomposition or a QR decomposition from the coupling nodes normal modes calculated by a cyclic modal analysis of the full structure. The blade eigenvalues of the clamped blade can be mistuned individually under consideration of the variance as well as the correlation between the different eigenvalues of the blades. Monte-Carlo-Simulations are performed to calculate the effect of these parameters on the forced response of a mistuned bladed disk for blade dominated modes. Furthermore, Monte-Carlo-Simulations and a constraint optimization approach is used to calculate the worst and best case blade patterns for specific blade patterns and blade patterns with distributed blade properties.
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Judge, John, Christophe Pierre, and Oral Mehmed. "Experimental Investigation of Mode Localization and Forced Response Amplitude Magnification for a Mistuned Bladed Disk." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0358.
Повний текст джерелаАнотація:
The results of an experimental investigation on the effects of random blade mistuning on the forced dynamic response of bladed disks are reported. The primary aim of the experiment is to gain understanding of the phenomena of mode localization and forced response blade amplitude magnification in bladed disks. A stationary, nominally periodic, twelve-bladed disk with simple geometry is subjected to a traveling-wave, out-of-plane, “engine order” excitation delivered via phase-shifted control signals sent to piezo-electric actuators mounted on the blades. The bladed disk is then mistuned by the addition of small, unequal weights to the blade tips, and it is again subjected to a traveling wave excitation. The experimental data is used to verify analytical predictions about the occurrence of localized mode shapes, increases in forced response amplitude, and changes in resonant frequency due to the presence of mistuning. Very good agreement between experimental measurements and finite element analysis is obtained. The out-of-plane response is compared and contrasted with the previously reported in-plane mode localization behavior of the same test specimen. This work also represents an important extension of previous experimental study by investigating a frequency regime in which modal density is lower but disk-blade interaction is significantly greater.
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Mignolet, Marc P., and Alejandro Rivas-Guerra. "Identification of Mistuning Characteristics of Bladed Disks From Free Response Data." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-583.
Повний текст джерелаАнотація:
The focus of the present investigation is on the estimation of the dynamic properties, i.e. masses, stiffnesses, natural frequencies, mode shapes and their statistical distributions, of turbomachine blades to be used in the accurate prediction of the forced response of mistuned bladed disks. As input to this process, it is assumed that the lowest natural frequencies of the blades alone have been experimentally measured, for example in a broach block test. Since the number of measurements is always less than the number of unknowns, this problem is indeterminate in nature. Two distinct approaches will be investigated to resolve the shortfall of data. The first one relies on the imposition of as many constraints as needed to insure a unique solution to this identification problem. Specifically, the mode shapes and modal masses of the blades are set to their design/tuned counterparts while the modal stiffnesses are varied from blade-to-blade to match the measured natural frequencies. The second approach, based on the maximum likelihood principle, yields estimates of all the structural parameters of the blades through the minimization of a specified “cost function”. The accuracy of these two techniques in predicting the forced response of mistuned bladed disks will be assessed on simple dynamic models of the blades.
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Salles, Loi¨c, Laurent Blanc, Fabrice Thouverez, Aleksander M. Gouskov, and Pierrick Jean. "Dynamic Analysis of a Bladed Disk With Friction and Fretting-Wear in Blade Attachments." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60151.
Повний текст джерелаАнотація:
Assembled bladed disks have many contact interfaces (blade-disk joint, blade shrouds, friction dampers...). Because of relative displacements at these interfaces, fretting-wear occurs, which affects negatively the lifetime of the structure. Methods exist to predict fretting-wear in quasi-static analysis. However they don’t predict all the phenomena observed in blade attachments on real industrial plants. This paper studies the assumption of a responsibility of dynamics for fretting-wear damage. A numerical treatment of fretting-wear under vibratory loading is proposed. The method is based on the Dynamical Lagrangian Frequency Time method. It models unilateral contact through Coulomb’s friction law. The basic idea is to separate time in two scales, slow scale for tribological phenomena and fast scale for dynamics. For a chosen number of periods of vibration, a steady state is assumed and the variables are decomposed in Fourier series. An Alternating Frequency Time procedure is performed to calculate the non-linear forces. Then, a Hybrid Powell’s algorithm is used as solver. A quasi-analytical expression of the Jacobian matrix decreases the duration of calculations. This expression is also used to predict new relative displacement at the interfaces due to the increase of wear depth. This method is similar to a prediction-correction method, with wear depth as the term of continuation. Numerical investigations on a bladed-disk with friction contact interfaces illustrate the performances of this method and show the coupling between dynamical and tribological phenomena.
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Boulton, Luis A., and Euro Casanova. "Reduced Order Model for a Two Stage Gas Turbine Including Mistuned Bladed Disks and Shaft Interaction." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59335.
Повний текст джерелаАнотація:
A number of previous works have suggested that in some cases the interaction between shaft and bladed disk modes could significantly modify the dynamics of the whole assembly i.e. the bladed disks mounted on a flexible shaft. This paper presents the application of a previously published reduced-order modeling technique to the dynamical modeling of a real two stage gas turbine, including the bladed disks and the shaft. In the resulting reduce order model, mistuning is included in the bladed disk models and the shaft is modeled using beam finite elements according to the classical rotordynamic approach. Generation of finite element parent model for the real turbine is presented and discussed as well as simplifications used in order to generate the reduced order model. Comparisons are made between the reduced model and the full finite element solution for free response frequencies and mode shapes in order to assess the methodology and to evaluate the impact of simplifying hypothesis considered in model generation. Finally, this work also shows interaction between shaft modes and bladed disk modes, therefore confirming that stage independent analysis might not be adequate for predicting the global dynamic response of some turbomachinery rotors.