Relevant bibliographies by topics / Blade flutter

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Blade flutter'

Author: Grafiati
Published: 4 June 2021
Last updated: 6 February 2022

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Journal articles on the topic "Blade flutter"

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Lobitz, Don W. "Parameter Sensitivities Affecting the Flutter Speed of a MW-Sized Blade." Journal of Solar Energy Engineering 127, no. 4 (July 12, 2005): 538–43. http://dx.doi.org/10.1115/1.2037091.

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With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5–9 m), both modern and early designs, the flutter speeds are in the range of 3.5–6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.
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Li, Nailu, Mark J. Balas, Pourya Nikoueeyan, Hua Yang, and Jonathan W. Naughton. "Stall Flutter Control of a Smart Blade Section Undergoing Asymmetric Limit Oscillations." Shock and Vibration 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/5096128.

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Stall flutter is an aeroelastic phenomenon resulting in unwanted oscillatory loads on the blade, such as wind turbine blade, helicopter rotor blade, and other flexible wing blades. Although the stall flutter and related aeroelastic control have been studied theoretically and experimentally, microtab control of asymmetric limit cycle oscillations (LCOs) in stall flutter cases has not been generally investigated. This paper presents an aeroservoelastic model to study the microtab control of the blade section undergoing moderate stall flutter and deep stall flutter separately. The effects of different dynamic stall conditions and the consequent asymmetric LCOs for both stall cases are simulated and analyzed. Then, for the design of the stall flutter controller, the potential sensor signal for the stall flutter, the microtab control capability of the stall flutter, and the control algorithm for the stall flutter are studied. The improvement and the superiority of the proposed adaptive stall flutter controller are shown by comparison with a simple stall flutter controller.
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Sun, Da-Gang, Jin-Jun Guo, Yong Song, Bi-juan Yan, Zhan-Long Li, and Hong-Ning Zhang. "Flutter stability analysis of a perforated damping blade for large wind turbines." Journal of Sandwich Structures & Materials 21, no. 3 (April 28, 2017): 973–89. http://dx.doi.org/10.1177/1099636217705290.

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The flutter stability of wind turbine blades is one of the important contents in the research of wind turbines. The bending stiffness of blades has decreased with the development of large-sized wind turbines. To achieve damping flutter-suppressing on the long spanwise blades, perforated damping blade was proposed under the consideration of the structural damping factor and the structural stiffness in this paper. Through the study of the unit cell, the deformation model was established and the structural loss factor of the perforated damping blade was derived. The undamped blade and the perforated damping blade, combined with the relevant parameters of a 1500 kW wind turbine blade, were established to simulate the flutter-suppressing abilities and the structural stability. The dynamic response analysis was accomplished with the large deformation theory, and the MPC algorithm was used to realize grid mobile and data delivery, according to the Newmark time integration method. The comparison results show that the perforated damping blade has both a higher structural damping factor and a better structural stiffness.
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Wang, Hao, Jiao Jiao Ding, Bing Ma, and Shuai Bin Li. "The Time Domain Analysis of the Flutter of Wind Turbine Blade Combined with Eigenvalue Approach." Advanced Materials Research 860-863 (December 2013): 342–47. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.342.

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The aeroelasticity and the flutter of the wind turbine blade have been emphasized by related fields. The flutter of the wind turbine blade airfoil and its condition will be focused on. The eigenvalue method and the time domain analysis method will be used to solve the flutter of the wind turbine blade airfoil respectively. The flutter problem will be firstly solved using eigenvalue approach. The flutter region, where the flutter will occur and anti-flutter region, where the flutter will not occur, will be obtained directly by judging the sign of the real part of the characteristic roots of the blade system. Then the time domain analysis of flutter of wind turbine blade will be carried out through the use of the four-order Runge-Kutta numerical methods, the flutter region and the anti-flutter region will be gotten in another way. The time domain analysis can give the changing treads of the aeroelastic responses in great detail than those of the eigenvalue method. The flap displacement of wind turbine blade airfoil will change from convergence to divergence, and change from divergence to convergence extremely suddenly. During the flutter region, the flutter of wind turbine blade will occur extremely dramatically. The flutter region provided by the time domain analysis of the flutter of the blade airfoil accurately coincides with the results of eigenvalue approach, therefore the simulation results are reliable and credible.
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Saren, V. E. "Calculating blade ring flutter." Journal of Applied Mechanics and Technical Physics 38, no. 5 (September 1997): 728–34. http://dx.doi.org/10.1007/bf02467885.

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Gill, John D., Vincent R. Capece, and Ronald B. Fost. "Experimental Methods Applied in a Study of Stall Flutter in an Axial Flow Fan." Shock and Vibration 11, no. 5-6 (2004): 597–613. http://dx.doi.org/10.1155/2004/596706.

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Flutter testing is an integral part of aircraft gas turbine engine development. In typical flutter testing blade mounted sensors in the form of strain gages and casing mounted sensors in the form of light probes (NSMS) are used. Casing mounted sensors have the advantage of being non-intrusive and can detect the vibratory response of each rotating blade. Other types of casing mounted sensors can also be used to detect flutter of rotating blades. In this investigation casing mounted high frequency response pressure transducers are used to characterize the part-speed stall flutter response of a single stage unshrouded axial-flow fan. These dynamic pressure transducers are evenly spaced around the circumference at a constant axial location upstream of the fan blade leading edge plane. The pre-recorded experimental data at 70% corrected speed is analyzed for the case where the fan is back-pressured into the stall flutter zone. The experimental data is analyzed using two probe and multi-probe techniques. The analysis techniques for each method are presented. Results from these two analysis methods indicate that flutter occurred at a frequency of 411 Hz with a dominant nodal diameter of 2. The multi-probe analysis technique is a valuable method that can be used to investigate the initiation of flutter in turbomachines.
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Wang, Si-wen, Jing-long Han, Quan-long Chen, Hai-wei Yun, and Xiao-mao Chen. "New Method for Analyzing the Flutter Stability of Hingeless Blades with Advanced Geometric Configurations in Hovering." International Journal of Aerospace Engineering 2020 (February 17, 2020): 1–16. http://dx.doi.org/10.1155/2020/1891765.

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A new method used to analyze the aeroelastic stability of a helicopter hingeless blade in hovering has been developed, which is especially suitable for a blade with advanced geometric configuration. This method uses a modified doublet-lattice method (MDLM) and a 3-D finite element (FE) model for building the aeroelastic equation of a blade in hovering. Thereafter, the flutter solution of the equation is calculated by the V-g method, assuming blade motions to be small perturbations about the steady equilibrium deflection. The MDLM, which is suitable to calculate the unsteady aerodynamic force of nonplanar rotor blade in hovering, is developed from the doublet-lattice method (DLM). The structural analysis tool is the commercial software ANSYS. The comparisons of the obtained results against those in the literatures show the capabilities of the MDLM and the method of structural analysis. The flutter stabilities of swept tip blades with different aspect ratios are analyzed using the new method developed in this work and the usual method on the basis of the unsteady strip theory and beam model. It shows that considerable differences appear in the flutter rotational velocities with the decrease of the aspect ratio. The flutter rotational velocities obtained by the present method are evidently lower than those obtained by the usual method.
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Abdel-Rahim, A., F. Sisto, and S. Thangam. "Computational Study of Stall Flutter in Linear Cascades." Journal of Turbomachinery 115, no. 1 (January 1, 1993): 157–66. http://dx.doi.org/10.1115/1.2929200.

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Aeroelastic interaction in turbomachinery is of prime interest to opertors, designers, and aeroelasticans. Operation at off-design conditions may promote blade stall; eventually the stall pattern will propagate around the blade annulus. The unsteady periodic nature of propagating stall will force blade vibration and blade flutter may occur if the stall propagation frequency is entrained by the blade natural frequency. In this work a computational scheme based on the vortex method is used to simulate the flow over a linear cascade of airfoils. The viscous effect is confined to a thin layer, which determines the separation points on the airfoil surfaces. The preliminary structural model is a two-dimensional characteristic section with a single degree of freedom in either bending or torsion. A study of the relationship between the stall propagation frequency and the blade natural frequency has been conducted. The study shows that entrainment, or frequency synchronization, occurs, resulting in pure torsional flutter over a certain interval of reduced frequency. A severe blade torsional amplitude (of order 20 deg) has been computed in the entrainment region, reaching its largest value in the center of the interval. However, in practice, compressor blades will not sustain this vibration and blade failure may occur before reaching such a large amplitude. Outside the entrainment interval the stall propagation is shown to be independent of the blade natural frequency. In addition, computational results show that there is no entrainment in the pure bending mode. Rather, “de-entrainment” occurs with similar flow conditions and similar stall frequencies, resulting in blade buffeting in pure bending.
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Wang, Hao, Bing Ma, and Jiao Jiao Ding. "The Analysis of the Flutter Region of Wind Turbine Blade." Applied Mechanics and Materials 423-426 (September 2013): 1520–23. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.1520.

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As the wind turbine blade is becoming larger and larger, the flutter of the wind turbine blade has been paid great attention by many fields. The flutter region of the wind turbine blade airfoil was focused on. The equation of motion for the flutter of blade airfoil was established, based on the simplified aerodynamic force and torque. The flutter analysis of wind turbine blade was carried out with the four-order Runge-Kutta methods, and so the flutter region of the blade airfoil can be obtained. The results show that, there are two critical tip speed ratios for the given blade airfoil. When the tip speed ratio is below the low critical speed ratio, the blade airfoil is convergent. At the low tip speed ratio, the blade airfoil system will become divergent from convergent condition. When the tip speed ratio is between the low critical tip speed ratio and the high one, the blade airfoil system will diverge. At the high tip speed ratio, the system will become convergent from divergent condition. When the tip speed ratio is above the high critical tip speed ratio, the blade airfoil system will converge again. In addition, the torsional angular displacement and velocity always keep convergent, the flap velocity is slightly divergent, because they are not sensible to the change of the tip speed ratio, and they are difficult to cause flutter, so the torsional motion will be more stable than flap motion for the given blade airfoil. It can provide one of references for the determination of the blade airfoil.
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Kobayashi, H. "Annular Cascade Study of Low Back-Pressure Supersonic Fan Blade Flutter." Journal of Turbomachinery 112, no. 4 (October 1, 1990): 768–77. http://dx.doi.org/10.1115/1.2927720.

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Low back-pressure supersonic fan blade flutter in the torsional mode was examined using a controlled-oscillating annular cascade test facility. Precise data of unsteady aerodynamic forces generated by shock wave movement, due to blade oscillation, and the previously measured data of chordwise distributions of unsteady aerodynamic forces acting on an oscillating blade, were joined and, then, the nature of cascade flutter was evaluated. These unsteady aerodynamic forces were measured by direct and indirect pressure measuring methods. Our experiments covered a range of reduced frequencies based on a semichord from 0.0375 to 0.547, six interblade phase angles, and inlet flow velocities from subsonic to supersonic flow. The occurrence of unstalled cascade flutter in relation to reduced frequency, interblade phase angle, and inlet flow velocity was clarified, including the role of unsteady aerodynamic blade surface forces on flutter. Reduced frequency of the flutter boundary increased greatly when the blade suction surface flow became transonic flow. Interblade phase angles that caused flutter were in the range from 40 to 160 deg for flow fields ranging from high subsonic to supersonic. Shock wave movement due to blade oscillation generated markedly large unsteady aerodynamic forces which stimulated blade oscillation.
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Dissertations / Theses on the topic "Blade flutter"

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Zhao, Fanzhou. "Embedded blade row flutter." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/51151.

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Modern gas turbine design continues to drive towards improved performance, reduced weight and reduced cost. This trend of aero-engine design results in thinned blade aerofoils which are more prone to aeroelastic problems such as flutter. Whilst extensive work has been conducted to study the flutter of isolated turbomachinery blades, the number of research concerning the unsteady interactions between the blade vibration, the resulting acoustic reflections and flutter is very limited. In this thesis, the flutter of such embedded blade rows is studied to gain understanding as for why and how such interactions can result in flutter. It is shown that this type of flutter instability can occur for single stage fan blades and multi-stage core compressors. Unsteady CFD computations are carried out to study the influence of acoustic reflections from the intake on flutter of a fan blade. It is shown that the accurate prediction of flutter boundary for a fan blade requires modelling of the intake. Different intakes can produce different flutter boundaries for the same fan blade and the resulting flutter boundary is a function of the intake geometry in front of it. The above finding, which has also been demonstrated experimentally, is a result of acoustic reflections from the intake. Through in-depth post-processing of the results obtained from wave-splitting of the unsteady CFD solutions, the relationship between the phase and amplitude of the reflected acoustic waves and flutter stability of the blade is established. By using an analytical approach to calculate the propagation and reflection of acoustic waves in the intake, a novel low- fidelity model capable of evaluating the susceptibility of a fan blade to flutter is proposed. The proposed model works in a similar fashion to the Campbell diagram, which allows one to identify the region (in compressor map) where flutter is likely to occur at early design stages of an engine. In the second part of this thesis, the influence of acoustic reflections from adjacent blade rows on flutter stability of an embedded rotor in a multi-stage compressor is studied using unsteady CFD computations. It is shown that reflections of acoustic waves, generated by the rotor blade vibration, from the adjacent blade rows have a significant impact on the flutter stability of the embedded rotor, and the computations using the isolated rotor can lead to significant over-optimistic predictions of the flutter boundary. Based on the understanding gained, an alternative strategy, aiming to reduce the computational cost, for the flutter analysis of such embedded blades is proposed. The method works by modelling the propagation and reflection of acoustic waves at the adjacent blade rows using an analytical method, whereby flutter computations of the embedded rotor can be performed in an isolated fashion by imposing the calculated reflected waves as unsteady plane sources. Computations using the proposed model can lead to two orders of magnitude reduction in computational cost compared with time domain full annulus multi-row computations. The computed results using the developed low-fidelity model show good correlation with the results obtained using full annulus multi-row models.
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Dong, Bonian. "Numerical simulation of wakes, blade-vortex interaction, flutter, and flutter suppression by feedback control." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134810/.

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Bell, David Lloyd. "Three dimensional unsteady flow for an oscillating turbine blade." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4794/.

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An experimental and computational study, motivated by the need to improve current understanding of blade flutter in turbomachinery and provide 3D test data for the validation of advanced computational methods for the prediction of this aeroelastic phenomenon, is presented. A new, low speed flutter test facility has been developed to facilitate a detailed investigation into the unsteady aerodynamic response of a turbine blade oscillating in a three dimensional bending mode. The facility employs an unusual configuration in which a single turbine blade is mounted in a profiled duct and harmonically driven. At some cost in terms of modelling a realistic turbomachinery configuration, this offers an important benefit of clearly defined boundary conditions, which has proved troublesome in previous work performed in oscillating cascade experiments. Detailed measurement of the unsteady blade surface pressure response is enabled through the use of externally mounted pressure transducers, and an examination of the techniques adopted and experimental error indicate a good level of accuracy and repeatability to be attained in the measurement of unsteady pressure. A detailed set of steady flow and unsteady pressure measurements, obtained from five spanwise sections of tappings between 10% and 90% span, are presented for a range of reduced frequency. The steady flow measurements demonstrate a predominant two-dimensional steady flow, whilst the blade surface unsteady pressure measurements reveal a consistent three dimensional behaviour of the unsteady aerodynamics. This is most especially evident in the measured amplitude of blade surface unsteady pressure which is largely insensitive to the local bending amplitude. An experimental assessment of linearity also indicates a linear behaviour of the unsteady aerodynamic response of the oscillating turbine blade. These measurements provide the first three dimensional test data of their kind, which may be exploited towards the validation of advanced flutter prediction methods. A three dimensional time-marching Euler method for the prediction of unsteady flows around oscillating turbomachinery blades is described along with the modifications required for simulation of the experimental test configuration. Computationalsolutions obtained from this method, which are the first to be supported by 3D test data, are observed to exhibit a consistently high level of agreement with the experimental test data. This clearly demonstrates the ability of the computational method to predict the relevant unsteady aerodynamic phenomenon and indicates the unsteady aerodynamic response to be largely governed by inviscid flow mechanisms. Additional solutions, obtained from a quasi-3D version of the computational method, highlight the strong three dimensional behaviour of the unsteady aerodynamics and demonstrate the apparent inadequacies of the conventional quasi-3D strip methodology. A further experimental investigation was performed in order to make a preliminary assessment of the previously unknown influence of tip leakage flow on the unsteady aerodynamic response of oscillating turbomachinery blades. This was achievedthrough the acquisition of a comprehensive set of steady flow and unsteady pressure measurements at three different settings of tip clearance. The steady flow measurements indicate a characteristic behaviour of the tip leakage flow throughout the range of tip clearance examined, thereby demonstrating that despite the unusual configuration, the test facility provides a suitable vehicle for the investigation undertaken. The unsteady pressure data show the blade surface unsteady pressure response between 10% and 90% span to be largely unaffected by the variation in tip clearance. Although close examination of the unsteady pressure measurements reveal subtle trends in the first harmonic pressure response at 90% span, which are observed to coincide with localised regions where the tip leakage flow has a discernible impact on the steady flow blade loading characteristic. Finally, some recommendations for further work are proposed
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Rauchenstein, Werner J. "A 3D Theodorsen-based rotor blade flutter model using normal modes." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FRauchenstein.pdf.

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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 2002.
Thesis advisor(s): E. Roberts Wood, Mark A. Couch. Includes bibliographical references (p. 55-56). Also available online.
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Höhn, Wolfgang. "Numerical investigation of blade flutter at or near stall in axial turbomachines." Doctoral thesis, KTH, Energy Technology, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2934.

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During the design of the compressor and turbine stages oftoday's aeroengines aerodynamically induced vibrations becomeincreasingly important since higher blade load and betterefficiency are desired. Aerodynamically induced vibrations inturbomachines can be classified into two general categories,i.e. selfexcited vibrations, usually denoted as flutter, andforced response. In the first case the aerodynamic forcesacting on the structure are dependent on the motion of thestructure. In the latter case the aerodynamic forces can beconsidered to be independent of the structural motion. In thisthesis the development of a method based on the unsteady,compressible Navier-Stokes equations in two dimensions isdescribed in order to study the physics of flutter for unsteadyviscous flow around cascaded vibrating blades at stall.

The governing equations are solved by a finite differencetechnique in boundary fitted coordinates. The numerical schemeuses the Advection Upstream Splitting Method to discretize theconvective terms and central differences discretizing thediffusive terms of the fully non-linear Navier-Stokes equationson a moving H-type mesh. The unsteady governing equations areexplicitly and implicitly marched in time in a time-accurateway using a four stage Runge-Kutta scheme on a parallelcomputer or an implicit scheme of the Beam-Warming type on asingle processor. Turbulence is modelled using theBaldwin-Lomax turbulence model. The blade flutter phenomenon issimulated by imposing a harmonic motion on the blade, whichconsists of harmonic body translation in two directions and arotation, allowing an interblade phase angle betweenneighbouring blades. An aerodynamic instability is given whichcan lead to a flutter problem, if the computed unsteadypressure forces amplify the imposed blade motion.Non-reflecting boundary conditions are used for the unsteadyanalysis at inlet and outlet of the computational domain. Thecomputations are performed on multiple blade passages in orderto account for nonlinear effects. Unsteady boundary conditionsare developed considering primary and secondary gust effectstowards the investigation of the forced response problem withthe presented method.

Subsonic massively stalled and transonic separated unsteadyflow cases in compressor and turbine cascades are studied. Theresults, compared with experiments and the predictions of otherresearchers, show good agreement for inviscid and viscous flowcases for the investigated flow situations with respect to thesteady and unsteady pressure distribution on the blade in thevicinity of shocks and in separated flow areas.

The results show the applicability of the new scheme forstalled flow around cascaded blades. As expected the viscousand inviscid methods show different results in areas whereviscous effects are important, i.e. separated flow and shockwaves. In particular, different predictions for inviscid andviscous flow for the aerodynamic damping for the investigatedflow cases are found.

Keywords: turbomachinery, flutter, forced response, gust,unsteady aerodynamics, Navier-Stokes equations, AdvectionUpstream Splitting Method, implicit scheme, non-reflectingboundary conditions, gust boundary conditions, parallelcomputing

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Moyroud, François. "Fluid-structure integrated computational methods for turbomachinery blade flutter and forced response predictions /." Stockholm : Tekniska högsk, 1998. http://www.lib.kth.se/abs98/moyr1214.pdf.

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Moyroud, François. "Fluid-structure integrated computational methods for turbomachinery blade flutter and forced response predictions." Lyon, INSA, 1998. http://www.theses.fr/1998ISAL0101.

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Les ensembles disque-aubes des turbomachines modernes sont amenés à satisfaire des critères stricts en termes de stabilité aéroélastique et de réponse forcée. L'objectif de cette thèse est d'utiliser et de développer des techniques de modélisation, capables de prédire le phénomène de flottement et de quantifier les amplitudes de résonance des aubages de turbomachine. Pour le flottement, deux méthodes d'analyse aéroélastique sont considérées: la méthode énergétique (approche fluidestructure non-couplée) et le schéma de couplage modal (approche fluide-structure couplée). Ces modèles ont été installés dans le code de calcul STRUFLO qui offre des outils d'interface performants pour coupler divers codes de calcul. Des méthodes spécifiques sont utilisées afin de combiner plusieurs types d'analyses fluide et structure, et ainsi de progresser dans le sens d'un traitement général des interactions fluide-structure. A cet effet, le schéma de couplage modal est adapté pour être compatible avec des analyses modales d'aube seule ainsi que des analyses modales d'ensemble disque-aubes avec ou sans symétrie cyclique. Un maillage d'interface est utilisé pour résoudre les problèmes liés à l'incompatibilité des maillages fluide et structure à l'interface et une méthode d'interpolation/extrapolation permet de transférer les modes de vibration d'aube et les champs de pression instationnaire, du maillage structure au maillage aérodynamique et vice versa. Le désaccordage structure est l'une des caractéristiques pouvant considérablement modifier la stabilité aéroélastique et les amplitudes de résonance des aubages. A cet effet, deux méthodes de réduction ont été étudiées afin d'autoriser des analyses modales et de réponse forcée d'ensemble disque-aubes complet. Les techniques développées sont appliquées à l'étude des comportements dynamiques, aérodynamiques et aéroélastiques du fan transonique NASA Rotor 67, d'un fan transonique avec nageoires et d'un fan subsonique à large corde
The lightweight, high performance bladed-disks used in today's aeroengines must meet strict standards in terms of aeroelastic stability and resonant response characteristics. The research presented in this thesis is directed toward improved prediction and understanding of blade flutters and forced response problems in turbomachines. To address the blade flutter problem, two aeroelastic analysis methods are considered: the energy method (fluid-structure uncoupled approach) and the modal aeroelastic coupling scheme (fluid-structure coupled approach). The two methods have been implemented in the STRUFLO master code which is designed to provide fluid-structure interfaces for a library of structural and flow solvers. Especially tailored methods are used to couple or interface a wide range of structural and aerodynamic analyses. First, the modal aeroelastic coupling scheme is extended to deal with single blade, cyclic symmetric and full assembly modal analyses as weil as single and multiple blade passage unsteady aerodynamic analyses. Second, an interfacing grid technique is proposed to circumvent problems due to the presence of non-conforming fluid and structural grids at the interface. Finally, a grid-to-grid interpolation/extrapolation scheme is used to transfer blade mode shapes and blade surface unsteady pressures from the structural grid to the aerodynamic grid and vice versa. One structural characteristic of bladed-disks that can significantly impact bath on the aeroelastic stability and the resonant response is that of structural mistuning. With this respect, two reduction methods have been developed to perform full assembly modal analyses and forced response analyses. Various numerical applications are proposed to illustrate the applicability of the above mentioned methods including structural dynamic, aerodynamic and aeroelastic analyses of the NASA Rotor 67 unshrouded transonic fan, a shrouded transonic fan and a subsonic wide chard fan
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Mata, Sanjay. "A fast generalized single-passage method for multi-blade row forced response and flutter." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523742.

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Richards, Phillip W. "Design strategies for rotorcraft blades and HALE aircraft wings applied to damage tolerant wind turbine blade design." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53488.

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Offshore wind power production is an attractive clean energy option, but the difficulty of access can lead to expensive and rare opportunities for maintenance. Smart loads management (controls) are investigated for their potential to increase the fatigue life of damaged offshore wind turbine rotor blades. This study will consider two commonly encountered damage types for wind turbine blades, the trailing edge disbond (bond line failure) and shear web disbond, and show how 3D finite element modeling can be used to quantify the effect of operations and control strategies designed to extend the fatigue life of damaged blades. Modern wind turbine blades are advanced composite structures, and blade optimization problems can be complex with many structural design variables and a wide variety of aeroelastic design requirements. The multi-level design method is an aeroelastic structural design technique for beam-like structures in which the general design problem is divided into a 1D beam optimization and a 2D section optimization. As a demonstration of aeroelastic design, the multi-level design method is demonstrated for the internal structural design of a modern composite rotor blade. Aeroelastic design involves optimization of system geometry features as well as internal features, and this is demonstrated in the design of a flying wing aircraft. Control methods such as feedback control also have the capability alleviate aeroelastic design requirements and this is also demonstrated in the flying wing aircraft example. In the case of damaged wind turbine blades, load mitigation control strategies have the potential to mitigate the effects of damage, and allow partial operation to avoid shutdown. The load mitigation strategies will be demonstrated for a representative state-of-the-art wind turbine (126m rotor diameter). An economic incentive will be provided for the proposed operations strategies, in terms of weighing the cost and risk of implementation against the benefits of increased revenue due to operation of damaged turbines. The industry trend in wind turbine design is moving towards very large blades, causing the basic design criterion to change as aeroelastic effects become more important. An ongoing 100 m blade (205 m rotor diameter) design effort intends to investigate these design challenges. As a part of that effort, this thesis will investigate damage tolerant design strategies to ensure next-generation blades are more reliable.
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Jinghe, Ren. "Development of a Shrouded SteamTurbine Flutter Test Case." Thesis, KTH, Kraft- och värmeteknologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-225857.

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A shrouded blade was designed as a test case for flutter analysis of steam turbine. Flutter is a self-excitedvibration. It can lead to dramatic blade loss and high-cycle fatigue. Shrouded blade is more complicated onflutter analysis, because the mode shapes are more complex with bending and torsion components atdifferent phases. Moreover, the blade mode shape and frequency also vary with nodal diameter. Lack ofopen resource of shrouded blade, there were less researches about shrouded blade test case on flutter. The initial blade geometry was from Di Qi’s 3D free standing blade test case. The material of the blade isTitanium. The aim of current study is to design a 3D test case for realistic shrouded blade flutter analysis. The geometryof the proposed shrouded blade test case was fully described in this thesis report. ANSYS ICEM was usedfor presenting the geometry and generating mesh. ANSYS APDL was used for structural analysis.Parameters of shroud parts were based on literature reviews and engineers’ general suggestions. The modeshapes for the first family of modes were calculated and reported.
Ett höljeblad utformades som ett testfall för fladderanalys av ångturbin. Flutter är en självupphetsadvibration. Det kan leda till dramatisk bladförlust och högcykelutmattning. Höljeblad är mer kompliceratvid fladderanalys, eftersom modeformerna är mer komplexa med böjnings- och torsionskomponenter iolika faser. Dessutom varierar bladformsformen och frekvensen också med noddiameter. Brist på öppenresurs av höljet blad, det fanns mindre undersökningar om höljet blad test fall på flutter. Den ursprungligabladgeometrin var från Di Qis 3D frittstående bladprovfall. Bladets material är titan. Syftet med den aktuella studien är att designa ett 3D-testfall för realistisk hävd bladflöjtsanalys. Geometrinhos det föreslagna höljet av bladsprov beskrivs fullständigt i denna avhandlingsrapport. ANSYS ICEManvändes för att presentera geometrin och det genererande nätet. ANSYS APDL användes för strukturellanalys. Parametrar av höljesdelar baserades på litteraturrecensioner och ingenjörers allmänna förslag.Modeshistorierna för den första familjen av lägen beräknades och rapporterades.
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Books on the topic "Blade flutter"

1

United States. National Aeronautics and Space Administration., ed. Blade row interaction effects on flutter and forced response. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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Blade row interaction effects on flutter and forced response. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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1960-, Murthy Durbha V., and United States. National Aeronautics and Space Administration., eds. Aeroelastic modal characteristics of mistuned blade assemblies: Mode localization and loss of Eigenstructure. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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A 3D Theodorsen-Based Rotor Blade Flutter Model Using Normal Modes. Storming Media, 2002.

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Oral, Mehmed, and United States. National Aeronautics and Space Administration., eds. Optical measurement of unducted fan flutter. [Washington, DC]: NASA, 1991.

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Methodology of blade unsteady pressure measurement in the NASA transonic flutter cascade. [Cleveland, Ohio]: National Aeronautics and Space Administration, Glenn Research Center, 2002.

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V, Kaza K. R., and United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., eds. Analysis of an unswept propfan blade with a semiempirical dynamic stall model. [Washington, D.C.]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1989.

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United States. National Aeronautics and Space Administration., ed. On curve veering and flutter of rotating blades. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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United States. National Aeronautics and Space Administration., ed. On curve veering and flutter of rotating blades. [Washington, DC]: National Aeronautics and Space Administration, 1993.

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The effect of steady aerodynamic loading on the flutter stability of turbomachinery blading. [Washington, DC]: National Aeronautics and Space Administration, 1991.

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Book chapters on the topic "Blade flutter"

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Smati, L., S. Aubert, P. Ferrand, and F. Massão. "Comparison of Numerical Schemes to Investigate Blade Flutter." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 749–63. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_49.

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Sayma, A. I., M. Vahdati, J. S. Green, and M. Imregun. "Whole-Assembly Flutter Analysis of a Low Pressure Turbine Blade." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 347–59. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_23.

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Chew, J. W., J. G. Marshall, M. Vahdati, and M. Imregun. "Part-Speed Flutter Analysis of a Wide-Chord Fan Blade." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 707–24. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_46.

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Steer, Th. "Test Facility for Flutter Investigations with Variable Frequency of the Vibrating Blade." In Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines and Propellers, 603–16. New York, NY: Springer New York, 1993. http://dx.doi.org/10.1007/978-1-4613-9341-2_30.

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Isomura, Kousuke. "The Effect of Blade Vibration Mode on a Flutter in a Transonic Fan." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 725–32. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_47.

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Viswanatha Rao, A. N., V. P. S. Naidu, and Soumendu Jana. "Gas Turbine Engine Fan Blade Flutter Detection Using Casing Vibration Signals by Application of Recurrence Plots and Recurrence Quantification Analysis." In Lecture Notes in Mechanical Engineering, 375–89. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5701-9_31.

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Chiang, Hsiao-Wei D., and Sanford Fleeter. "Splitter Blades for Passive Turbomachine Flutter Control." In Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines and Propellers, 807–28. New York, NY: Springer New York, 1993. http://dx.doi.org/10.1007/978-1-4613-9341-2_41.

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Singh, Priya, V. K. Chawla, and N. R. Chauhan. "Flutter and Modal Analysis of Gas Turbine Compressor Blades." In Lecture Notes in Mechanical Engineering, 707–19. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0159-0_62.

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Rządkowski, R., V. Gnesin, and A. Kovalyov. "The 2D Flutter of a Bladed Disc in an Incompressible Flow." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 317–34. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_21.

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Panovsky, J., M. Nowinski, and A. Bölcs. "Flutter of Aircraft Engine Low Pressure Turbine Blades: Oscillating Cascade Experiments and Analysis." In Unsteady Aerodynamics and Aeroelasticity of Turbomachines, 815–29. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5040-8_53.

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Conference papers on the topic "Blade flutter"

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Széchényi, Edmond. "Fan Blade Flutter: Single Blade Instability or Blade to Blade Coupling?" In ASME 1985 International Gas Turbine Conference and Exhibit. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-gt-216.

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Different types of fan blade flutter occur at the various compressor flow regimes. Sub/transonic stall flutter and two forms of supersonic started flow flutter have been studied in a straight cascade wind tunnel. Results show clearly that these three common forms of flutter can exist as single-degree-of-freedom (single-blade instabilities). Cascade effects, though at times important, are never the only flutter mechanism: flutter limits are essentially controlled by single-blade aeroelastic coefficients, though blade-to-blade coupling arising from cascade effects can modify these limits according to the mode order. Thus, contrary to widespread practice, the fundamental approach to flutter problems should lie at least as much in the study of single blade flutter as in that of unsteady cascade effects. The two should anyhow best be considered separately when searching for a better physical insight.
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Namba, Masanobu, and Ayumi Kubo. "Aerodynamically Coupled Flutter of Multiple Blade Rows." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50315.

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This paper deals with the aeroelastic instability of vibrating multiple blade rows under aerodynamic coupling with each other. A model composed of three blade rows, e.g., rotor-stator-rotor, in which blades of the two rotor cascades are simultaneously vibrating, is considered. The generalized aerodynamic force on a vibrating blade consists of the component induced by the vibrating motion of the blade itself and those induced by vibrations not only of other blades in the same cascade but also of blades in another cascade. To evaluate the aerodynamic forces, the unsteady lifting surface theory for the model of three blade rows is applied. The equations describing motions of blades are coupled via the aerodynamic forces. The so-called k method is applied to determine the critical flutter conditions. A numerical study has been conducted. The flutter boundaries are compared with those for a single blade row. It is shown that the effect of the aerodynamic coupling significantly modifies the critical flutter conditions.
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3

Vahdati, Mehdi, George Simpson, and Mehmet Imregun. "Mechansims for Wide-Chord Fan Blade Flutter." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-60098.

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This paper describes a detailed wide-chord fan blade flutter analysis with emphasis on flutter bite. The same fan was used with three different intakes of increasing complexity to explain flutter mechanisms. Two types of flutter, namely stall flutter and acoustic flutter, were identified. The first intake is a uniform cylinder for which there are no acoustic reflections. Only stall flutter, driven by flow separation, can exist in this case. The second intake, based on the first one, has a ‘bump’ feature to reflect the fan’s forward pressure wave at a known location so that detailed parametric studies can be undertaken. The analysis revealed a mechanism for acoustic flutter, which is driven by the phase of the reflected wave. The third intake has the typical geometric features of a flight intake. The results indicate that flutter bite occurs when both stall and acoustic flutter happen at the same speed. It is also found that blade stiffening has no effect on aero-acoustic flutter.
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CHIANG, HSIAO-WEI, and SANFORD FLEETER. "Flutter control of incompressible flow turbomachine blade rows by splitter blades." In 27th Joint Propulsion Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-1900.

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Srivastava, R., and Theo G. Keith. "Shock Induced Flutter of Turbomachinery Blade Row." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53479.

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This paper describes the influence and effect of a normal shock wave on the flutter characteristics of a turbomachine blade row. High fidelity numerical analysis is used to calculate the energy exchange for a vibrating blade row in the presence of an oscillating normal shock wave. The 3-D Tenth Standard Cascade is used in the present study to calculate the influence of a shock on the energy exchange of blades undergoing a torsional vibration and to correlate the observations with an algebraic model. Effect of three parameters-distance of shock from elastic axis, inter-blade phase angle and vibration frequency are investigated. The results indicate that the three parameters strongly influence the flutter characteristics. The distance between shock location and elastic axis was found to have a linear effect on stability. Moving the elastic axis from downstream of the shock to upstream changes the sign of the stability characteristics as well. It was found that the shock induced energy exchange varied harmonically with inter-blade phase angle indicating the phase between shock motion and blade motion to be independent of inter-blade phase angle. The influence of vibration frequency on work done by the shock was found to be harmonic for reduced frequencies up to 2. The results also showed that either a positive or negative energy exchange could be induced by a shock depending upon the frequency of vibration. The influence of the shock wave on the unsteady flowfield was found to be linear for small amplitude blade oscillation. It was also found that the region of influence of the shock on the work could be divided into primary and secondary regions with work in the primary region being influenced directly by the shock motion. The work in the secondary region was found to be influenced by flow variations induced by shock motion downstream of the shock.
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Vahdati, Mehdi, Nigel Smith, and Fanzhou Zhao. "Influence of Intake on Fan Blade Flutter." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25859.

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The main aim of this paper is to study the influence of upstream reflections on flutter of a fan blade. To achieve this goal, flutter analysis of a complete fan assembly with an intake duct and the downstream OGVs (whole LP domain) is undertaken using a validated CFD model. The computed results show good correlation with measured data. Due to space constraints, only upstream (intake) reflections are analyzed in this paper. It will be shown that the correct prediction of flutter boundary for a fan blade requires modeling of the intake and different intakes would produce different flutter boundaries for the same fan blade. However, the ‘blade only’ and intake damping are independent and the total damping can be obtained from the sum of the two contributions. In order to gain further insight into the physics of the problem, the pressure waves created by blade vibration are split into an upstream and a downstream traveling wave in the intake. The splitting of the pressure wave allows one to establish a relationship between the phase and amplitude of the reflected waves and flutter stability of the blade. By using this approach, a simple reflection model can be used to model the intake effects.
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Whitehead, D. S., and D. H. Evans. "Flutter of Grouped Turbine Blades." In ASME 1992 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/92-gt-227.

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An analysis is presented to predict flutter in a wheel of turbine blades which are connected together into a number of identical groups. The natural frequencies and mode shapes of a group are assumed to be known. The unsteady aerodynamic coefficients for free-standing blades are assumed to be known from an unsteady aerodynamic program, and FINSUP is used here. The work fed into the vibration by the aerodynamic forces is then calculated. This is illustrated by two examples of low pressure steam turbine blade rows GR-1 and GR-2. On GR-1 the three modes considered are all found to be stable, but on GR-2 the lowest frequency mode shows some instability. Tying the blades together in groups is found to be stabilizing. Blade response, measured by a Blade Vibration Monitor at two different installations, is shown for a range of operating conditions. The measured responses indicate the GR-1 blade is stable whereas the GR-2 blade shows, at the lowest frequency, high response that is dependent on turbine operating conditions.
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Xiaojie, Zhang, Wang Yanrong, Han Le, Zhao Jiazhe, and Luo Yanbin. "Influence of Upstream and Downstream Stator Blades on the Rotor Blade Flutter Characteristics." In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85353.

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One of the important issues in turbomachinery flutter analysis is the intra-row interaction effects. The present work is aimed at a systematic research of the adjacent rows effects on aerodynamic damping. Three models, the isolated rotor, the IGV-rotor and the rotor-stator model, are performed to identify the upstream and downstream stator effects on the rotor blade. It is found that the aerodynamic damping from the stage flutter simulations are quite different from that from isolated rotor. In addition, the mixing-plane method is also applied to calculate the stage flutter characteristics and its accuracy of flutter predictions is compared with the time-marching method. It is indicated that the main difference of aerowork density between MP and TM is in the tip area, and in some cases the result from MP method can be misleading. Furthermore, study with different axial gaps illustrates that there is a nonmonotonic relationship between the rotor blade aerodynamic damping and the gap in the rotor-stator model, while the rotor blade aerodynamic damping monotonically increases with the gap in the IGV-rotor model.
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9

Dhadwal, Harbans S., Marc Radzikowski, Dmitri Strukov, and Anatole Kurkov. "Real Time Flutter Monitoring System for Turbomachinery." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53992.

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A fiber optic laser probe based system is described for real time monitoring of flutter in rotating turbomachinery. The digital flutter monitoring system is designed for continuous processing of blade tip timing data at a rate of 10 MB/s. A USB2.0 interface provides un-interrupted real time processing of the data. The blade tip arrival times are measured with a 50 MHz bscillator and a 24-bit pipelined counter architecture. A graphical user interface provides on-line interrogation of any blade tip from any light probe sensor. Alternatively, data from all blades can be superimposed into a single composite scatter plot displaying the vibration amplitude of each blade. A hardware platform was developed to simulate a seventy two bladed turbine operating at 15,000 rpm. Blade tip responses from three light probes were generated in an infinite loop, providing reproducible and controlled conditions for testing the vibration monitoring system. Time interval measurements were consistently made with a single count error in a 24-bit count vector. Real time testing was done using a two blade rotor mounted in an evacuated chamber at the Spin Rig Facility at the NASA Glen Research Center. The shaft in this facility was suspended by two radial magnetic bearings and the nonsynchronous vibration was communicated to the blades through the magnetic bearing. The shaft motion was much smaller than the blade vibratory amplitude, realistically simulating flutter vibrations. Nonsynchronous vibratory amplitudes for the first mode were of the order of twenty mils and for the second mode of the order of a few mils.
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10

Wu, X., M. Vahdati, A. I. Sayma, and M. Imregun. "A Numerical Investigation of Aeroacoustic Fan Blade Flutter." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38454.

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This paper reports the results of an ongoing research effort to explain the underlying mechanisms for aeroacoustic fan blade flutter. Using a 3D integrated aeroelasticity method and a single passage blade model that included a representation of the intake duct, the pressure rise vs. mass flow characteristic of a fan assembly was obtained for the 60%–80% speed range. A novel feature was the use of a downstream variable-area nozzle, an approach that allowed the determination of the stall boundary with good accuracy. The flutter stability was predicted for the 2 nodal diameter assembly mode arising from the first blade flap mode. The flutter margin at 64% speed was predicted to drop sharply and the instability was found to be independent of stall effects. On the other hand, the flutter instability at 74% speed was found to be driven by flow separation. Further post-processing of the results at 64% speed indicated significant unsteady pressure amplitude build-up inside the intake at the flutter condition, thus highlighting the link between the acoustic properties of the intake duct and fan blade flutter.
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