Relevant bibliographies by topics / Rotor-blade system

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  2. Dissertations / Theses
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Academic literature on the topic 'Rotor-blade system'

Author: Grafiati
Published: 13 April 2024

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Journal articles on the topic "Rotor-blade system"

1

Ngui, Wai Keng, M. Salman Leong, L. M. Hee, and Ahmed M. Abdelrhman. "Detection of Twisted Blade in Multi Stage Rotor System." Applied Mechanics and Materials 773-774 (July 2015): 144–48. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.144.

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This paper studies the detection of twisted blade in a multi stages rotor system. Experimental study was undertaken to simulate twisted blade conditions in a three stages rotor system. The feasibility of vibration analysis as the technique to detect twisted blade based on the rotor operating frequency and its blade passing frequency was investigated in this study. Experimental results show that twisted blade can be easily detected by looking into the pattern of the vibration spectrum and its individual peaks.
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Dalli, Uğbreve;ur, and Şcedilefaatdin Yüksel. "Identification of Flap Motion Parameters for Vibration Reduction in Helicopter Rotors with Multiple Active Trailing Edge Flaps." Shock and Vibration 18, no. 5 (2011): 727–45. http://dx.doi.org/10.1155/2011/675791.

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An active control method utilizing the multiple trailing edge flap configuration for rotorcraft vibration suppression and blade loads control is presented. A comprehensive model for rotor blade with active trailing edge flaps is used to calculate the vibration characteristics, natural frequencies and mode shapes of any complex composite helicopter rotor blade. A computer program is developed to calculate the system response, rotor blade root forces and moments under aerodynamic forcing conditions. Rotor blade system response is calculated using the proposed solution method and the developed program depending on any structural and aerodynamic properties of rotor blades, structural properties of trailing edge flaps and properties of trailing edge flap actuator inputs. Rotor blade loads are determined first on a nominal rotor blade without multiple active trailing edge flaps and then the effects of the active flap motions on the existing rotor blade loads are investigated. Multiple active trailing edge flaps are controlled by using open loop controllers to identify the effects of the actuator signal output properties such as frequency, amplitude and phase on the system response. Effects of using multiple trailing edge flaps on controlling rotor blade vibrations are investigated and some design criteria are determined for the design of trailing edge flap controller that will provide actuator signal outputs to minimize the rotor blade root loads. It is calculated that using the developed active trailing edge rotor blade model, helicopter rotor blade vibrations can be reduced up to 36% of the nominal rotor blade vibrations.
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Lee, Yu-Tai, and JinZhang Feng. "Potential and Viscous Interactions for a Multi-Blade-Row Compressor." Journal of Turbomachinery 126, no. 4 (October 1, 2004): 464–72. http://dx.doi.org/10.1115/1.1740778.

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A computationally efficient time-accurate vortex method for unsteady incompressible flows through multiple blade row systems is presented. The method represents the boundary surfaces using vortex systems. A local coordinate system is assigned to each independently moving blade row. Blade shed vorticity is determined from two generating mechanisms and convected using the Euler equation. The first mechanism of vorticity generation is a potential mechanism from a nonlinear unsteady pressure-type Kutta condition applied at the blade trailing edges. The second mechanism is a viscous mechanism from a viscous wake vorticity (VWV) model implemented to simulate the viscous shear layers on the blade pressure and suction sides. Two different two-blade-row compressor systems, a rotor/stator (R/S) system and a stator/rotor (S/R) system, were used to investigate the interaction forces on each blade row. Computational results of the potential and viscous interaction forces are presented and compared to measurements. The comparison suggests that the viscous wake interaction accounts for 25–30% of the peak loading for an axial spacing of 10% chord length between the blade rows. The efficient computational method is particularly attractive for blade indexing study. Therefore a three-blade-row rotor/stator/rotor (R1/S/R2) compressor system is used to demonstrate the indexing calculations between the two rotor positions. Resultant forces on each blade row are presented for ten rotor indexing positions and three axial gap sizes for the gaps between R1 and S and between S and R2. The unsteady peak-to-peak force can reach 10–15% of inflow dynamic head for the gap spacing investigated. The minimum-to-maximum variation of the unsteady force can account for 40–50% of averaged unsteady force.
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Lu, Zhenyong, Shun Zhong, Huizheng Chen, Yushu Chen, Jiajie Han, and Chao Wang. "Modeling and Dynamic Characteristics Analysis of Blade-Disk Dual-Rotor System." Complexity 2020 (January 25, 2020): 1–13. http://dx.doi.org/10.1155/2020/2493169.

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In this paper, a simplified dynamic model of a dual-rotor system coupled with blade disk is built, and the effects of blade parameters of an aircraft engine on the dynamic characteristics of a dual-rotor system are studied. In the methodology, the blade is simplified as a cantilever structure, and the dynamical equations are obtained by the means of a finite element method. The amplitude-frequency response curves and orbits of shaft centre-vibration shape diagram are used to analyze the effects of blade parameters on dynamic characteristics of a dual-rotor system. The results indicate that the properties of the blades have huge impacts on the critical speed and other dynamic characteristics of the system. With an increase of the length of the blade, the second-order critical speed decreases obviously, but the first-order critical speed is almost invariant; this means that the blades attached on the low-pressure compressor do not affect the first-order critical speed of the dual-rotor system. Meanwhile, note that the high-pressure rotor and low-pressure turbine rotor can excite the first-order resonance of the dual-rotor system, while the low-pressure compressor rotor can only excite the second-order resonance, and then the dynamic model of this six-point support dual-rotor system can further be simplified as a relatively independent single-rotor system with one disk and a four-support dual-rotor system with dual disks.
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Wang, Nanfei, Chao Liu, and Dongxiang Jiang. "Prediction of transient vibration response of dual-rotor-blade-casing system with blade off." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 14 (April 4, 2019): 5164–76. http://dx.doi.org/10.1177/0954410019839884.

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Fan blade off occurring in a running rotor of the turbofan engine dual-rotor system will cause a sudden unbalance and inertia asymmetry, which results in large impact load and consequently induces the rubbing between blade and casing. In order to reveal the transient dynamic response characteristics of actual aero-engine when fan blade off event occurs, the dynamic model of dual-rotor-blade-casing system is developed, in which the distribution characteristics of the stiffness and mass, the load transfer, and the coupling effects of dual-rotor and casing are included. Considering several excitations caused by blade off, the physical process and mechanical characteristics of the fan blade off event are described qualitatively. Considering that only the casing acceleration signal can be used for condition monitoring in actual aero-engine, the transient response including rotor vibration displacement and casing vibration acceleration during the instantaneous status are obtained. Due to the time-varying and highly nonlinear characteristics of vibration responses, frequency slice wavelet transform is employed to isolate the vibration signal features. The results show that the impact load induced by the sudden imbalance causes significant increase of vibration amplitude. The rubbing action between blade and rotor will impose constraint effects on the rotor, which decreases the transient vibration amplitude. The inertia asymmetry has a big impact on the transient response. The vibration characteristics of casing acceleration under blade off are similar to those of rotor displacement, while casing acceleration response attenuates to stable value faster and is more sensitive to high-frequency components of vibration.
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Lu, Xin, Jie Tang, and Liwen Wang. "Simulation and Experimental Study on Rotor System Dynamic Analysis with the Blade-Coating Rubbing Faults." Shock and Vibration 2021 (September 10, 2021): 1–15. http://dx.doi.org/10.1155/2021/2442760.

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In the modern turbo-machinery, reducing the clearance between the blade tip and casing inner face is an effective method to improve the power performance, but the clearance reduction leads to increased risk of blade-casing rubbing. In this paper, a blade-coating rubbing force model which considered the abradable coating scraping is developed to simulate the rotor system dynamic characteristics at blade-casing rubbing faults with abradable coating. An experimental tester is established to simulate the rotor system blade-casing rubbing faults; the AlSi-ployphenyl ester abradable coating is prepared and introduced into the blade-casing experiment to verify the model. After the vibration and force analysis in simulation and experiment, the dynamic characteristics and the influence factors of blade-casing rubbing rotor system are studied.
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Zalkind, Daniel S., Gavin K. Ananda, Mayank Chetan, Dana P. Martin, Christopher J. Bay, Kathryn E. Johnson, Eric Loth, D. Todd Griffith, Michael S. Selig, and Lucy Y. Pao. "System-level design studies for large rotors." Wind Energy Science 4, no. 4 (November 11, 2019): 595–618. http://dx.doi.org/10.5194/wes-4-595-2019.

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Abstract. We examine the effect of rotor design choices on the power capture and structural loading of each major wind turbine component. A harmonic model for structural loading is derived from simulations using the National Renewable Energy Laboratory (NREL) aeroelastic code FAST to reduce computational expense while evaluating design trade-offs for rotors with radii greater than 100 m. Design studies are performed, which focus on blade aerodynamic and structural parameters as well as different hub configurations and nacelle placements atop the tower. The effects of tower design and closed-loop control are also analyzed. Design loads are calculated according to the IEC design standards and used to create a mapping from the harmonic model of the loads and quantify the uncertainty of the transformation. Our design studies highlight both industry trends and innovative designs: we progress from a conventional, upwind, three-bladed rotor to a rotor with longer, more slender blades that is downwind and two-bladed. For a 13 MW design, we show that increasing the blade length by 25 m, while decreasing the induction factor of the rotor, increases annual energy capture by 11 % while constraining peak blade loads. A downwind, two-bladed rotor design is analyzed, with a focus on its ability to reduce peak blade loads by 10 % per 5∘ of cone angle and also reduce total blade mass. However, when compared to conventional, three-bladed, upwind designs, the peak main-bearing load of the upscaled, downwind, two-bladed rotor is increased by 280 %. Optimized teeter configurations and individual pitch control can reduce non-rotating damage equivalent loads by 45 % and 22 %, respectively, compared with fixed-hub designs.
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Christensen, René H., and Ilmar F. Santos. "Active Rotor-Blade Vibration Control Using Shaft-Based Electromagnetic Actuation." Journal of Engineering for Gas Turbines and Power 128, no. 3 (March 1, 2004): 644–52. http://dx.doi.org/10.1115/1.2056533.

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In this paper the feasibility of actively suppressing rotor and blade vibration via shaft-based actuation is studied. A mathematical model is derived, taking into account the special dynamical characteristics of coupled rotor-blade systems, such as centrifugal stiffened blades and parametric vibration modes. An investigation of controllability and observability shows that if the blades are properly mistuned, it is possible to suppress shaft as well as blade vibration levels by using only shaft-based actuation and sensing; though, in tuned bladed systems, shaft as well as blade actuation and sensing are required. In order to cope with the time-variant dynamics of the coupled rotor-blade system, a periodic time-variant modal controller is designed, implemented, and experimentally tested. A test rig built by four flexible blades is specially designed for this purpose. The rig is equipped with six electromagnetic actuators and different types of sensors (eddy-current displacement transducers, acceleration transducers, and strain gages) with the aim of monitoring and controlling shaft and blade vibration levels. Two different actively controlled rotor-blade system configurations are considered in the present study: (i) a tuned bladed rotor, controlled with help of actuators attached to the rotating blades and shaft-based actuators; (ii) a deliberately mistuned bladed rotor controlled only via shaft-based actuation. Experimental tests are carried out for both configurations. Some experimental problems regarding control implementation are identified and discussed, especially when the controller order and the number of actuators in the centralized control scheme become too high; though, for the mistuned bladed rotor controlled by using only shaft-based actuation, the controller works well.
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Abdelrhman, Ahmed M., M. Salman Leong, Yasin M. Hamdan, and Kar Hoou Hui. "Time Frequency Analysis for Blade Rub Detection in Multi Stage Rotor System." Applied Mechanics and Materials 773-774 (July 2015): 95–99. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.95.

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Blade fault is one of the most causes of failure in turbo machinery. This paper discussed the time frequency analysis for blade rubbing detection from casing vibration signal. Feasibility of Short Time Fourier Transform (STFT), Wigner-Ville distribution (WVD) and Choi-Williams distribution (CWD) were examined for blade rub detection in a multi stage blade system through an experimental data. Analysis results of the experimental data showed that these time frequency analysis methods have some inevitable deficiencies in segregating the blade passing frequency (BPF) components of the three rotor stage signals. However, CWD demonstrated a better time-frequency resolution in analyzing the multi stage rotor system signal.
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Qian, Xiaoru, Peigang Yan, Xiangfeng Wang, and Wanjin Han. "Numerical Analysis of Conjugated Heat Transfer and Thermal Stress Distributions in a High-Temperature Ni-Based Superalloy Turbine Rotor Blade." Energies 15, no. 14 (July 7, 2022): 4972. http://dx.doi.org/10.3390/en15144972.

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This paper establishes a multidisciplinary method combining conjugate heat transfer (CHT) and thermal stress for a high-temperature Ni-based superalloy turbine rotor blade with integrated cooling structures. A conjugate calculation is performed to investigate the coolant flow characteristics, heat transfer, and thermal stress of the rotor blade under rotating and stationary conditions to understand the effects of rotation on the multidisciplinary design of the blade. Furthermore, the maximum resolved shear stress among the 30-slip systems and the corresponding dominant slip system are obtained to predict the deformation tendency of the blade by employing the crystal plasticity finite element method (CPFEM) and considering the specified anisotropic blade material (GTD-111). The results show that the forces of rotation, including centrifugal and Coriolis forces, and their induced buoyancy force, alter the coolant flow field and thus affect the rotor blade’s heat transfer distribution compared with the stationary condition. The maximum temperature and thermal stress of the rotor blade under rotating conditions are reduced by 5% and 21% compared with that under the stationary condition, respectively. Compared with the stationary condition, the temperature and thermal stress distribution on the blade under the rotating condition are more uniform, especially on the suction side. In addition, the blade root connecting with the hub, the film holes near the leading-edge region at the blade root, the mid-chord of the suction surface, and the grooved blade tip are easily damaged by the enormous resolved shear stress and the interface effect of different types of dominant slip system under the two conditions. In this work, it was feasible to use the cascade cooling effect test to analyze the dynamic test results for the rotor blade. Furthermore, the thermal stress analysis based on the CPFEM can provide a superior level of blade cooling design than CHT by considering the anisotropic material characteristics of a turbine blade.
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Dissertations / Theses on the topic "Rotor-blade system"

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Pickering, Todd Michael. "Methods for Validation of a Turbomachinery Rotor Blade Tip Timing System." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/47496.

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This research developed two innovative test methods that were used to experimentally evaluate the performance of a novel blade tip timing (BTT) system from Prime Photonics, LC. The research focused on creating known blade tip offsets and tip vibrations so that the results from a BTT system can be validated. The topic of validation is important to the BTT field as the results between many commercial systems still are not consistent. While the system that was tested is still in development and final validation is not complete, the blade tip offset and vibration frequency validation results show that this BTT system will be a valuable addition to turbomachinery research and development programs once completed. For the first test method custom rotors were created with specified blade tip offsets. For the blade tip offset alternate measurement, the rotors were optically scanned and analyzed in CAD software with a tip location uncertainty of 0.1 mm. The BTT system agreed with the scanned results to within 0.13 mm. Tests were also conducted to ensure that the BTT system identified and indexed the blades properly. The second developed test method used an instrumented piezoelectric blade to create known dynamic deflections. The active vibration rotor was able to create measureable deflection over a range of frequencies centered on the first bending mode of the blade. The results for the 110 Hz, 150 Hz, 180 Hz first bending resonance, 200 Hz, and 1036 Hz second bending resonance cases are presented. A strain gage and piezoelectric sensor were attached to the active blade during the dynamic deflection tests to provide an alternate method for determining blade vibration frequency. The BTT system correctly identified the active blade excitation frequencies as well as a 120 Hz frequency from the drive motor. This thesis also explored applying BTT methods and testing to more realistic blade geometry and vibration. Blade vibrations are usually classified by their frequency relative to the rotation speed. Synchronous vibrations are integer multiples of the rotational speed and are often excited by struts or vanes fixed to the engine case. For this reason, special probe placement algorithms were explored that use sine curve fitting to optimize the probe placement. Knowing how the blade will vibrate at operation before testing is critical as well. In preparation for future research, ANSYS Mechanical was used to predict the first three modes of a PT6A-28 first stage rotor blade at 1,966, 5,539, and 7,144 Hz. These frequencies were validated to within 4% using scanning laser vibrometry. The simulation was repeated at speed to produce a Campbell Diagram to highlight synchronous excitation crossings.
Master of Science
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Prechtl, Eric Frederick. "Design and implementation of a piezoelectric servo-flap actuation system for helicopter rotor individual blade control." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/9266.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.
Includes bibliographical references (p. 177-186).
A novel new actuator for helicopter rotor control, the X-Frame Actuator, was developed, demonstrating superior performance for applications requiring compact, fast acting, large stroke actuation. The detailed experimental characterization of this actuator is described, including bench-top output energy measurements and transverse shake test performance. A Mach scaled rotor blade utilizing the X-Frame actuator to power a trailing edge servo-flap near the tip was also designed, manufactured and tested. A description of the design and composite manufacturing of the rotor blade and servo-flap is presented. Preliminary bench tests of the active blade actuation system are also presented. The hover tests of the active blade provided transfer function identification of the performance of the actuator in producing flap deflections, and the response of the rotor from deflections of the servo-flap. At the highest field level of 60 V/mil P-P the actuation system produces 7.75 degrees of quasi-static peak-to-peak flap deflection in hover. The servo-flap produces significant control authority, especially near the 3/rev frequency that would be important for the CH-47. Scaled to a full-sized CH-47, the rotor can produce over 16,000 lb peak-to-peak thrust variation at 3/rev, which is 32% of the aircraft's gross weight. Closed-loop feedback control was experimentally applied to the model rotor system. Both single frequency and combined frequency controllers were successfully implemented on the rotor. Most significantly, simultaneous control of 1/rev, 3/rev, 4/rev, 5/rev, and 6/rev harmonic vibration has been successfully demonstrated. The peak vibrations were eliminated at each frequency, as well as the vibrations over a small bandwidth surrounding each peak. Experimental comparison of continuous time versus discrete time control has shown the former to be a more effective approach for vibration reduction.
by Eric Blade Prechtl.
Ph.D.
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Roth, Brian D. "Acoustic source and data acquisition system for a helicopter rotor blade-vortex interaction (BVI) noise reduction experiment." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA326229.

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Thesis (M.S. in Engineering Acoustics) Naval Postgraduate School, December 1996.
"December 1996." Thesis advisor(s): Robert M. Keolian, Steven R. Baker. Includes bibliographical references (p. 59). Also available online.
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Mansisidor, Michael R. "Resonant blade response in turbine rotor spin tests using a laser-light probe non-intrusive measurement system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://sirsi.nps.navy.mil/uhtbin/hyperion-image/j02Mar%5FMansisidor.pdf.

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Sánchez, Jiménez Oscar. "On the stochastic response of rotor-blade models with Floquet modal theory : applications to time-dependent reliability of tidal turbine blades." Electronic Thesis or Diss., Normandie, 2023. http://www.theses.fr/2023NORMIR39.

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Le sujet d'étude est la réponse d’un système mécanique déterministe en rotation et soumis à des sollicitations stochastiques. Pour cela, un modèle mécano-probabiliste est développé, résultant de la combinaison de deux éléments : le système mécanique au comportement dit non-standard, et les sollicitations, représentées par un champ stochastique corrélé. L'application vise l'analyse fiabiliste d’une hydrolienne, décrite par un modèle mécanique d’ordre réduit. Plusieurs méthodes sont présentées, comparées et leurs limitations sont mises en évidence. Les résultats obtenus sont contrastés avec ceux de la bibliographie. En particulier, l’aspect innovant se trouve dans le type de quantité mécanique modélisée, le traitement et l'interprétation des quantités modales, et le type de processus stochastique considéré comme sollicitation. Plus précisément, le modèle dynamique développé décrit une classe de systèmes mécaniques de type rotor-pale. Il a été construit par une combinaison judicieuse de résultats des domaines de l'éolien, l'hydrolien, la dynamique des rotors et des vibrations mécaniques. La formulation lagrangienne de la mécanique analytique est utilisée pour obtenir les équations du système dynamique. L'assemblage obtenu avec des composants élastiques linéaires, introduits avec leur comportement modal, produit des termes instationnaires, résultant dans des équations différentielles ordinaires à coefficients périodiques. Pour l'analyse de ce problème mécanique déterministe, l’analyse modale numérique traditionnelle est ici étendue grâce à la théorie de Floquet. La réponse du système est formulée en termes des exposants caractéristiques du système et des vecteurs propres de Floquet, ou vecteurs propres périodiques, permettant une représentation modale de la matrice de transition de Floquet. Diverses méthodes peuvent alors être appliquées pour l'analyse modale du système et on propose une nouvelle méthode basée sur la représentation temps-fréquence grâce aux ondelettes périodiques généralisées. Pour considérer les sollicitations aléatoires instationnaires et non-gaussiennes, on utilise une écriture innovante pour la propagation des moments. L’avantage de cette technique vient de l’aspect pratique et systématique des développements, ce qui est particulièrement avantageux lorsqu'elle est appliquée à des champs spatio-temporels instationnaires. En combinant cette technique avec une méthode d’estimation de la densité de probabilité basée sur le principe d’entropie maximale, nous arrivons à l’estimation de la distribution des valeurs extrêmes de la réponse cherchée en considérant le problème de dépassement d’un seuil par ce processus instationnaire, permettant ainsi la résolution du problème posé en termes de fiabilité dépendante du temps
The response of a deterministic rotating mechanical system under stochastic excitation is studied. A mechanical-probabilistic model is developed to combine the relevant characteristics of both aspects of the study: the behavior of this non-standard class of mechanical system and the random properties of correlated stochastic fields describing load processes. The results are applied to a reliability analysis of a reduced order model of a tidal turbine. Semi-analytic and empirical ( in the Monte-Carlo simulation sense) results are obtained, compared and contrasted. The results are framed with respect to the existing literature, and it is found that they provide an innovative treatment of the problem, in terms of the dynamical choices reflected in the model, in the presentation and interpretation of the modal aspects of the system, and in the type of stochastic inputs considered. We develop a dynamical model describing a broad class of mechanical system that models a rotor-blade structure. The model is informed by careful consideration of previous results, with the aim of constructing a reduced model that captures essential characteristics of the vibratory behavior of the structure. Lagrangian formalism is utilized to obtain the equations of motion. The presence of elastic components, which are discretized in a modal way, results in a system of ordinary differential equations with periodic coefficients. The Floquet theory of Linear time-periodic systems is applied on the deterministic dynamical model to synthesize an extension of traditional modal analysis to systems with periodic coefficients. The response of the system is formulated in terms of Floquet exponents and the associated Floquet periodic eigenvectors, from which the Floquet State Transition Matrix can be obtained. Several methods are applied to the modal study of the system, and a new time-frequency approach is proposed based on PGHW wavelets and its associated scalogram. Using an innovative notation to describe probabilistic moments of stochastic quantities, a moment propagation scheme is presented and exploited. The advantages of the treatment, particularly in the case of spatio-temporal stochastic fields, is in its applicability and systematic structure of development. This moment propagation strategy is coupled with a maximum entropy formulation to reconstruct the probability density function of the response and obtain important descriptors of the response, such as the Extreme Value Distribution. The moment propagation technique presented is applied to nonstationary processes. The results from Modal Floquet theory are integrated into this analysis. The problem of crossings of a certain threshold is considered for this type of nonstationary stochastic process. Their response is shown to yield a time-dependent reliability problem, which is resolved using the estimated EVD and then by numerical simulation
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Pawar, Prashant M. "Structural Health Monitoring Of Composite Helicopter Rotor Blades." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/273.

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Helicopter rotor system operates in a highly dynamic and unsteady aerodynamic environment leading to severe vibratory loads on the rotor system. Repeated exposure to these severe loading conditions can induce damage in the composite rotor blade which may lead to a catastrophic failure. Therefore, an interest in the structural health monitoring (SHM) of the composite rotor blades has grown markedly in recent years. Two important issues are addressed in this thesis; (1) structural modeling and aeroelastic analysis of the damaged rotor blade and (2) development of a model based rotor health monitoring system. The effect of matrix cracking, the first failure mode in composites, is studied in detail for a circular section beam, box-beam and two-cell airfoil section beam. Later, the effects of further progressive damages such as debonding/delamination and fiber breakage are considered for a two-cell airfoil section beam representing a stiff-inplane helicopter rotor blade. It is found that the stiffness decreases rapidly in the initial phase of matrix cracking but becomes almost constant later as matrix crack saturation is reached. Due to matrix cracking, the bending and torsion stiffness losses at the point of matrix crack saturation are about 6-12 percent and about 25-30 percent, respectively. Due to debonding/delamination, the bending and torsion stiffness losses are about 6-8 percent and about 40-45 percent after matrix crack saturation, respectively. The stiffness loss due to fiber breakage is very rapid and leads to the final failure of the blade. An aeroelastic analysis is performed for the damaged composite rotor in forward flight and the numerically simulated results are used to develop an online health monitoring system. For fault detection, the variations in rotating frequencies, tip bending and torsion response, blade root loads and strains along the blade due to damage are investigated. It is found that peak-to-peak values of blade response and loads provide a good global damage indicator and result in considerable data reduction. Also, the shear strain is a useful indicator to predict local damage. The structural health monitoring system is developed using the physics based models to detect and locate damage from simulated noisy rotor system data. A genetic fuzzy system (GFS) developed for solving the inverse problem of detecting damage from noise contaminated measurements by hybridizing the best features of fuzzy logic and genetic algorithms. Using the changes in structural measurements between the damaged and undamaged blade, a fuzzy system is generated and the rule-base and membership functions optimized by genetic algorithm. The GFS is demonstrated using frequency and mode shape based measurements for various beam type structures such as uniform cantilever beam, tapered beam and non-rotating helicopter blade. The GFS is further demonstrated for predicting the internal state of the composite structures using an example of a composite hollow circular beam with matrix cracking damage mode. Finally, the GFS is applied for online SHM of a rotor in forward flight. It is found that the GFS shows excellent robustness with noisy data, missing measurements and degrades gradually in the presence of faulty sensors/measurements. Furthermore, the GFS can be developed in an automated manner resulting in an optimal solution to the inverse problem of SHM. Finally, the stiffness degradation of the composite rotor blade is correlated to the life consumption of the rotor blade and issues related to damage prognosis are addressed.
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Pawar, Prashant M. "Structural Health Monitoring Of Composite Helicopter Rotor Blades." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/273.

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Helicopter rotor system operates in a highly dynamic and unsteady aerodynamic environment leading to severe vibratory loads on the rotor system. Repeated exposure to these severe loading conditions can induce damage in the composite rotor blade which may lead to a catastrophic failure. Therefore, an interest in the structural health monitoring (SHM) of the composite rotor blades has grown markedly in recent years. Two important issues are addressed in this thesis; (1) structural modeling and aeroelastic analysis of the damaged rotor blade and (2) development of a model based rotor health monitoring system. The effect of matrix cracking, the first failure mode in composites, is studied in detail for a circular section beam, box-beam and two-cell airfoil section beam. Later, the effects of further progressive damages such as debonding/delamination and fiber breakage are considered for a two-cell airfoil section beam representing a stiff-inplane helicopter rotor blade. It is found that the stiffness decreases rapidly in the initial phase of matrix cracking but becomes almost constant later as matrix crack saturation is reached. Due to matrix cracking, the bending and torsion stiffness losses at the point of matrix crack saturation are about 6-12 percent and about 25-30 percent, respectively. Due to debonding/delamination, the bending and torsion stiffness losses are about 6-8 percent and about 40-45 percent after matrix crack saturation, respectively. The stiffness loss due to fiber breakage is very rapid and leads to the final failure of the blade. An aeroelastic analysis is performed for the damaged composite rotor in forward flight and the numerically simulated results are used to develop an online health monitoring system. For fault detection, the variations in rotating frequencies, tip bending and torsion response, blade root loads and strains along the blade due to damage are investigated. It is found that peak-to-peak values of blade response and loads provide a good global damage indicator and result in considerable data reduction. Also, the shear strain is a useful indicator to predict local damage. The structural health monitoring system is developed using the physics based models to detect and locate damage from simulated noisy rotor system data. A genetic fuzzy system (GFS) developed for solving the inverse problem of detecting damage from noise contaminated measurements by hybridizing the best features of fuzzy logic and genetic algorithms. Using the changes in structural measurements between the damaged and undamaged blade, a fuzzy system is generated and the rule-base and membership functions optimized by genetic algorithm. The GFS is demonstrated using frequency and mode shape based measurements for various beam type structures such as uniform cantilever beam, tapered beam and non-rotating helicopter blade. The GFS is further demonstrated for predicting the internal state of the composite structures using an example of a composite hollow circular beam with matrix cracking damage mode. Finally, the GFS is applied for online SHM of a rotor in forward flight. It is found that the GFS shows excellent robustness with noisy data, missing measurements and degrades gradually in the presence of faulty sensors/measurements. Furthermore, the GFS can be developed in an automated manner resulting in an optimal solution to the inverse problem of SHM. Finally, the stiffness degradation of the composite rotor blade is correlated to the life consumption of the rotor blade and issues related to damage prognosis are addressed.
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Den, Heijer Francois Malan. "Development of an active pitch control system for wind turbines / F.M. den Heijer." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2635.

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A wind turbine needs to be controlled to ensure its safe and optimal operation, especially during high wind speeds. The most common control objectives are to limit the power and rotational speed of the wind turbine by using pitch control. Aero Energy is a company based in Potchefstroom, South Africa, that has been developing and manufacturing wind turbine blades since 2000. Their most popular product is the AE1kW blades. The blades have a tendency to over-speed in high wind speeds and the cut-in wind speed must be improved. The objective of this study was to develop an active pitch control system for wind turbines. A prototype active pitch control system had to be developed for the AE1kW blades. The objectives of the control system are to protect the wind turbine from over-speeding and to improve start-up performance. An accurate model was firstly developed to predict a wind turbine’s performance with active pitch control. The active pitch control was implemented by means of a two-stage centrifugal governor. The governor uses negative or stalling pitch control. The first linear stage uses a soft spring to provide improved start-up performance. The second non-linear stage uses a hard spring to provide over-speed protection. The governor was manufactured and then tested with the AE1kW blades. The governor achieved both the control objectives of over-speed protection and improved start-up performance. The models were validated by the results. It was established that the two-stage centrifugal governor concept can be implemented on any wind turbine, provided the blades and tower are strong enough to handle the thrust forces associated with negative pitch control. It was recommended that an active pitch control system be developed that uses positive pitching for the over-speed protection, which will eliminate the large thrust forces. Keywords: pitch control, wind turbine, centrifugal governor, over-speed protection, cut-in wind speed, blade element-momentum theory, rotor, generator, stall, feathering.
Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2009.
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Fowler, Leslie Paige. "Application of the Filtered-X LMS Algorithm for Disturbance Rejection in Time-Periodic Systems." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/36768.

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Extensive disturbance rejection methods have been established for time-invariant systems. However, the development of these techniques has not focused on application to time-periodic systems in particular until recently. The filtered-X LMS algorithm is regarded as the best disturbance rejection technique for aperiodic systems by many, as has been proven in the acoustics industry for rejecting unwanted noise. Since this is essentially a feedforward approach, we might expect its performance to be good with respect to time-periodic systems in which the disturbance frequency is already known. The work presented in this thesis is an investigation of the performance of the filtered-X LMS algorithm for disturbance rejection in time-periodic systems. Two cases are examined: a generalized linear, time-periodic system and the helicopter rotor blade in forward flight. Results for the generalized system show that the filtered-X LMS algorithm does converge for time-periodic disturbance inputs and can produce very small errors. For the helicopter rotor blade system the algorithm is shown to produce very small errors, with a 96%, or 14 dB, reduction in error from the open-loop system. The filtered-X LMS disturbance rejection technique is shown to provide a successful means of rejecting timeperiodic disturbances for time-periodic systems.
Master of Science
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10

Griffith, Khadir A. "Performance Evaluation of RF Systems on Rotorcrafts." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274103965.

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Books on the topic "Rotor-blade system"

1

Y, Chu Alphonse, Talbot Peter D, and United States. National Aeronautics and Space Administration., eds. Synthesis of individual rotor blade control system for gust alleviation: Final report. [Washington, D.C: National Aeronautics and Space Administration, 1990.

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Acoustic source and data acquisition system for a helicopter rotor blade-vortex interaction (BVI) noise reduction experiment. Monterey, Calif: Naval Postgraduate School, 1996.

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H, Mirick Paul, Langston Chester W, and Langley Research Center, eds. Rotating shake test and modal analysis of a model helicopter rotor blade. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1997.

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M, Bartie K., and Ames Research Center, eds. Hover performance tests of baseline metal and Advanced Technology Blade (ATB) rotor systems for the XV-15 tilt rotor aircraft. Moffett Field, Calif: National Aeronautics and Space Administration, Ames Research Center, 1988.

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National Aeronautics and Space Administration (NASA) Staff. Synthesis of Individual Rotor Blade Control System for Gust Alleviation. Independently Published, 2018.

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Acoustic Source and Data Acquisition System for a Helicopter Rotor Blade-Vortex Interaction (BVI) Noise Reduction Experiment. Storming Media, 1996.

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Resonant Blade Response in Turbine Rotor Spin Tests Using a Laser-Light Probe Non-Intrusive Measurement System. Storming Media, 2002.

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National Aeronautics and Space Administration and NASA. Preliminary Design Study of Advanced Composite Blade and Hub and Nonmechanical Control System for the Tilt-Rotor Aircraft - Volume 2 : Project Planning Data: February 1 1980. Independently Published, 2022.

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Book chapters on the topic "Rotor-blade system"

1

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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Zhang, Jian, Shiping Song, Chao Li, Yanhong Ma, and Jie Hong. "Dynamic Analysis and Safety Design for Aero-Engine Rotor-Support System Under the Blade-off." In Proceedings of the 11th IFToMM International Conference on Rotordynamics, 1–14. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-40455-9_1.

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Lin, Jiewei, Bin Wu, Xin Lu, Jian Xu, Junhong Zhang, and Huwei Dai. "Numerical Simulation of Aero-Engine Rotor-Blade-coating Coupling System with Rub-impact Fault and Its Dynamic Response." In Proceedings of the 11th IFToMM International Conference on Rotordynamics, 56–75. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-40459-7_4.

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Ma, Yanhong, Yongfeng Wang, and Jie Hong. "Dynamic Model and Theoretical Investigation for the Fan-Blade Out Event in the Flexible Rotor System of Aero-Engine." In Mechanisms and Machine Science, 18–33. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99272-3_2.

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Luthfi, Muhammad, Leo Van Gunawan, Muhamad Ghozali, Reza Aditya, and Saeful Anwar. "Experimental Study of Multistage Rotor in Gravitational Water Vortex Turbine System with Various Gap Placement Positions and Blade Phase-Shift Angles." In Proceedings of the International Conference on Applied Science and Technology on Engineering Science 2023 (iCAST-ES 2023), 992–1000. Dordrecht: Atlantis Press International BV, 2024. http://dx.doi.org/10.2991/978-94-6463-364-1_91.

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Soodani, Sara, SeyedVahid Hosseini, Mohammad Hakimi, and Mohammad Akhlaghi. "The Effect of Vane Number in Casing Treatment of an Axial-Flow Compressor." In Springer Proceedings in Energy, 341–50. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-30960-1_32.

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AbstractImprovement of the operating range of compressors will help the power and energy plant to work more flexibly to integrate with other energy generation systems. The stall, rotating stall, and resulting surge are the most dominant limiting phenomenon in axial compressor operating envelop. Several active and passive methods have been employed to eliminate occurring of these phenomena and to extend compressors’ stable range. Among these, casing treatment is one of the most useful methods. This study aims to investigate the effect of the number of stationary blades on the performance and stall margin of an axial compressor through numerical simulation. Casing treatments in two different configurations of 33.3 and 53.5% of rotor blade tip exposure and with six different numbers of vanes, 30, 40, 60, 80, 90, and 120, are simulated with computational fluid dynamics in ANSYS software. The numerical simulation is validated with available experimental data. The results reveal that in a high rotor exposure configuration, the highest number of vanes provides the best performance for the compressor. However, in a low exposure configuration, the optimum number of the vanes, 90 for the 33.3% exposure, can be found with the proposed numerical procedure based on stall margin improvement.
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Schleupen, Josef, Heiko Engemann, Mohsen Bagheri, Stephan Kallweit, and Peter Dahmann. "Developing a Climbing Maintenance Robot for Tower and Rotor Blade Service of Wind Turbines." In Advances in Intelligent Systems and Computing, 310–19. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-49058-8_34.

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Maraev, Anton A., Gennady A. Shut, Alexander N. Timofeev, Sergey V. Mikheev, Artem Kh Akhmerov, Liliana S. Rodikova, and Igor A. Konyakhin. "Effect of Illumination on Errors in Estimation of a Rotor Blade Chord Value During Intelligent Video Endoscopy of a Closed Steam Turbine Cylinder." In Studies in Systems, Decision and Control, 169–85. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97004-8_13.

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Sun, Fengnan, Yan Zhu, Qiyou Cheng, Siwen Wang, and Longtao Xing. "Simulation and Analysis of Dynamic Characteristics of Tilt Rotor/Wing Coupling System." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde221044.

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Considering the coupling effects of elastic wing, elastic blade, rigid nacelle and connection points between systems, the mathematical model of the coupling system including wing/nacelle/tilting rotor is established. Based on the eigenvalue method, the overall modal changes of the rotor installed on the wing and the effects of speed and offset on the dynamic characteristics of the system are studied. The results show that the wing joint motion mainly affects the backward and forward modes of rotor flapping. Different rotor rotation speeds cause varying degrees of modal frequencies of wings in different flight modes, especially the wing flapping mode. The nacelle tilt angle causes significant changes in wing waving frequency, and other modes are basically unaffected. The shaft length mainly affects the wing shimmy and torsional mode in vertical flight, and the offset basically does not affect the wing modes in the forward flight stage.
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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.

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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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Conference papers on the topic "Rotor-blade system"

1

Yi, Liu. "Dynamic analysis of rotor blade system." In 2017 19th International Conference on Advanced Communication Technology (ICACT). IEEE, 2017. http://dx.doi.org/10.23919/icact.2017.7890250.

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Jones, Henry. "A Nonintrusive Rotor Blade Vibration Monitoring System." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-084.

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A technique for measuring turbine engine rotor blade vibrations has been developed as an alternative to conventional strain-gage measurement systems. Light probes are mounted on the periphery of the engine rotor casing to sense the precise blade passing times of each blade in the row. The timing data are processed on-line to identify (1) individual blade vibration amplitudes and frequencies, (2) interblade phases, (3) system modal definitions, and (4) blade static deflection. This technique has been effectively applied to both turbine engine rotors and plant rotating machinery.
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Yi, Liu. "The dynamical model of rotor blade system." In 2016 18th International Conference on Advanced Communication Technology (ICACT). IEEE, 2016. http://dx.doi.org/10.1109/icact.2016.7423381.

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Yi, Liu. "The dynamical model of rotor blade system." In 2016 18th International Conference on Advanced Communication Technology (ICACT). IEEE, 2016. http://dx.doi.org/10.1109/icact.2016.7423382.

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5

Al-Nassar, Y. N. "Finite Element Modeling of Blade-Rotor System in Turbomachinery." In ASME 2003 Pressure Vessels and Piping Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/pvp2003-2179.

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Modal analysis of Blade-Disk system under the effect of bearing flexibility is investigated. The present study has considered soft to hard bearing flexibility. The main objective here is to read from the modal analysis results the frequencies that are carrying out some information on blade vibration. The modal analysis shows that that there are few frequencies that are changing with the change of bearing flexibility. These are shaft mode only, shaft-blade nature, disk mode only, disk-blade nature, and blade mode only. The shaft-blade modes are the ones of concern here.
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Adewusi, Surajudeen. "Detection of Rotating Blade Faults From Lateral Vibrations of a Rotor-Disk-Blade System." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46567.

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Competition and high quality requirements in the industries have necessitated the need for reliable rotating machines. This can be partly achieved by continuous monitoring of operation conditions to detect any fault before it causes serious problem or breakdown of rotating machines. The detection of faults in rotating blades via direct blade vibration measurements and analysis is somewhat difficult because blades often operate in a very harsh environment (gas turbine blades are rotating in high temperature and pressure environment). This paper presents indirect detection of blade faults from lateral vibrations of a rotor-disk-blade system, which can easily be measured, using laboratory test-rig. A rotor, disk, 6 normal blades and 3 blades with different defects were designed. The modal parameters of the normal and defective blades were determined experimentally and by modal analysis using ANSYS. The lateral vibrations, in the x- and y-axis, of the rotor-disk system with normal 6 blades and with 5 normal blades and 1 defective blade at a time were measured and analyzed. The results revealed that defective blades showed some distinct characteristics in the frequency domain, which can be used to identify blade faults in a bladed rotor-disk system.
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Simmons, Harold R., Douglas L. Michalsky, Kenneth E. Brewer, and Anthony J. Smalley. "Measuring Rotor and Blade Dynamics Using an Optical Blade Tip Sensor." In ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-091.

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This paper describes an optical measurement system for monitoring combustion turbine blade tips. The sensor measures distance to a blade tip using triangulation of reflected laser light. The system accomplishes triangulation using an optical position sensing device and high speed data acquisition. In this way, it is able to monitor not only average and minimum blade tip clearances, but to monitor the variations of individual blade tip clearances. By appropriate signal processing, it is possible to determine rotor vibration at the probe axial location, variations in shaft DC position, transient losses in blade tip clearance, the potential for tip and seal rubs, vibrations of individual blades in the tangential direction, and rotor torsional vibration at the probe location. Some aspects of blade and torsional vibrations would require more than one probe. The paper presents static calibration data for the measurement system, showing its degree of linearity and range. The paper also presents data obtained on a dynamic blade test rig with tip passing speeds and blade widths comparable to those encountered in high performance industrial combustion turbines. Data from this rig have been processed to show rotor vibration, shift in shaft average position, blade-to-blade tip clearance variation, and variation with speed of minimum blade tip clearance. The measurement system is designed to produce data suitable for use in the monitoring of advanced combustion turbine durability and the diagnosis of turbine functional problems, static and dynamic.
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Karlsson, B. Agne, C. Pontus Bergström, and J. Thomas F. Domeij. "Rotor Dynamic Response at Blade Loss." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-201.

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This paper shows the influence of the method of modelling the support structure, i.e. the casings, support struts and skid, on the rotor dynamics and forced response in a gas turbine structure. Numerical examples, based on the conceptual design of GTX100 in the simple cycle configuration, are given for the blade loss case. The standard method of analysing the rotor dynamics of a stationary gas- or steam-turbine rotor train, with hydrodynamic bearings, is based on beam theory. The bearings are modelled as a system of linear springs and dampers and are in some cases modelled as if there is no cross-coupling between the bearings. The support structure is normally based on a simple FE-analysis. This method is normally sufficient for the analysis of rotor dynamics characteristics at normal running if the stiffness of the bearings are much lower than the stiffness of the support structure. In analysing the case of blade loss, the dynamic characteristics of the casing and the support structure have a much stronger influence on the rotor dynamics and the forced response in the structure. At the high unbalance forces present at a blade loss, the stiffness of the bearings will be of the same magnitude as that of the structure. Results are given and discussed for the analysis of the rotor dynamic response based on coupled 3D-FE models, and on beam theory with the dynamic characteristics of the support structure described by various FE models.
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Mileshin, Victor, Victor Fateev, and Alexander Stepanov. "Blade Fissure Determination by Means of Blade Tip-Timing System." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76848.

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Since the turbomachinery came into existence there is control issue of rotor blade stress condition and blade health monitoring both aero engines in service and in process of impeller machines refinement. This issue relevance is to rotor blade failure lead to serious damage of compressor and aero engines in whole. The timely detection rotor blade failure such as a fissure can prevent emergency and enabled to avoid costly repair. One of the techniques for determination of rotor blades vibration behavior is the blade tip-timing method. Of late years this method find use for turbo machines testing and it has already considerable theoretical and practical experience of application. This work presents the application of blade tip-timing system for measurements of rotor blades vibration parameters in order to detect of rotor blade fissures. The paper presents the instance of blade fissure detection in model fan C180-2 with blade number equaled 18 and circumferential speed 400 m/s by means of non-contact vibration measurement system during the input non-uniformity test. Also data processing of tests was carried out for rotor blade fissure detection in compressor stage. Some assessment criteria of rotor blade condition are considered for blade health monitoring. The purpose of this work is to estimate as a rule famous methodologies of rotor blade failure determination in turbo machines by means blade tip-timing system during the test.
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Okabe, Akira, Takeshi Kudo, Hideo Yoda, Shigeo Sakurai, Osami Matsushita, and Koki Shiohata. "Rotor-Blade Coupled Vibration Analysis by Measuring Modal Parameters of Actual Rotor." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59471.

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The designers of rotor shafts and blades for a traditional turbine-generator set typically employed their own models and process by neglecting the coupled torsional effect. The torsional coupled umbrella mode of recent longer blades systems designed for higher output and efficiency tends to have nearly doubled the frequency of electric disturbance (i.e., 100 or 120 Hz). In order to precisely estimate the rotor-blade coupled vibration of rotating shafts, the analysis must include a process to identify the parameters of a mathematical model by using a real model. In this paper we propose the use of a unique quasi-modal technique based on a concept similar to that of the modal synthesis method, but which represents a unique method to provide a visually reduced model. An equivalent mass-spring system is produced for uncoupled umbrella mode and modal parameters are measured in an actual turbine rotor system. These parameters are used to estimate the rotor-blade coupled torsional frequencies of a 700-MW turbine-generator set, with the accuracy of estimation being verified through field testing.
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