Relevant bibliographies by topics / Stall Flutter

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

Academic literature on the topic 'Stall Flutter'

Author: Grafiati
Published: 4 June 2021
Last updated: 6 September 2023

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Journal articles on the topic "Stall Flutter"

1

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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2

OKAWA, Hirohisa. "Stall flutter of helicopter blade." Journal of the Japan Society for Aeronautical and Space Sciences 33, no. 377 (1985): 332–39. http://dx.doi.org/10.2322/jjsass1969.33.332.

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3

Ekaterinaris, J. A., and M. F. Platzer. "Numerical Investigation of Stall Flutter." Journal of Turbomachinery 118, no. 2 (1996): 197–203. http://dx.doi.org/10.1115/1.2836626.

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Unsteady, separated, high Reynolds number flow over an airfoil undergoing oscillatory motion is investigated numerically. The compressible form of the Reynolds-averaged governing equations is solved using a high-order, upwind biased numerical scheme. The turbulent flow region is computed using a one-equation turbulence model. The computed results show that the key to the accurate prediction of the unsteady loads at stall flutter conditions is the modeling of the transitional flow region at the leading edge. A simplified criterion for the transition onset is used. The transitional flow region is computed with a modified form of the turbulence model. The computed solution, where the transitional flow region is included, shows that the small laminar/transitional separation bubble forming during the pitch-up motion has a decisive effect on the near-wall flow and the development of the unsteady loads. Detailed comparisons of computed fully turbulent and transitional flow solutions with experimental data are presented.
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TOKISUE, Hiromitsu, Yasuo MACHIDA, and Hiroyuki TAKATA. "Stall flutter of airfoils of leading edge stall type." Transactions of the Japan Society of Mechanical Engineers Series B 55, no. 510 (1989): 337–43. http://dx.doi.org/10.1299/kikaib.55.337.

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5

Bethi, Rajagopal V., Sai Vishal Reddy Gali, and J. Venkatramani. "Identifying route to stall flutter through stochastic bifurcation analysis." MATEC Web of Conferences 211 (2018): 02011. http://dx.doi.org/10.1051/matecconf/201821102011.

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The interaction of an elastic structure such as an airfoil and fluid flow can give rise to nonlinear phenomenon such as limit cycle oscillations, period doubling or chaos. These phenomena are indicated by a change in the stability behaviour of the dynamical known as bifurcations. Presence of viscous effects in the fluid flow can give rise to flow separation which causes a stability change in the system that is identified to happen via a Hopf bifurcation. In such cases, the airfoil exhibits limit cycle oscillations which are torsionally dominant, known as stall flutter. Despite identifying the route to stall flutter under uniform flow conditions, investigating a stall problem under stochastic wind has received minimal attention. The ability of fluctuating flows to change the stability boundaries and disrupt the route to flutter, compels the need to carry out a stochastic analysis of stalling airfoils. Study of stall flutter in such systems under the influence of a time varying sinusoidal gust is undertaken and the route to flutter is identified by carrying out a stochastic bifurcation analysis.
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6

Chi, R. M., and A. V. Srinivasan. "Some Recent Advances in the Understanding and Prediction of Turbomachine Subsonic Stall Flutter." Journal of Engineering for Gas Turbines and Power 107, no. 2 (1985): 408–17. http://dx.doi.org/10.1115/1.3239741.

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In this paper, some recent advances in the understanding and prediction of subsonic flutter of jet engine fan rotor blades are reviewed. Among the topics discussed are (i) the experimental evidence of mistuning in flutter responses, (ii) new and promising unsteady aerodynamic models for subsonic stall flutter prediction, (iii) an overview of flutter prediction methodologies, and (iv) a new research effort directed toward understanding the mistuning effect on subsonic stall flutter of shrouded fans. A particular shrouded fan of advanced design is examined in the detailed technical discussion.
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7

Zhang, Xiaolin, Haipeng Sun, Yingbo Wang, Shanyao Li, Changle Sun, and Tingrui Liu. "Nonlinear Stall Flutter Suppression of Wind Turbine Blade Based on LMI Method." Journal of Physics: Conference Series 2173, no. 1 (2022): 012045. http://dx.doi.org/10.1088/1742-6596/2173/1/012045.

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Abstract Aiming at the failure of stall flutter in aeroelastic system of wind turbine blade, the active control process of stall flutter based on linear matrix inequality (LMI) design is described. The structural model is a typical blade section model based on spring-mass-damper, and the aerodynamic force is the ONERA stall aerodynamic model suitable for pure pitch motion. Based on the state variables, the nonlinear aeroelastic equations are expanded by Taylor series and linearized by low order approximation. The state feedback gain is calculated through LMI, and the time domain response stability analysis and stall flutter suppression method based on linearization are studied. The simulation results show that the maximum amplitude is greatly reduced after flutter control, and the system can be stabilized in a short time.
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8

Clark, William S., and Kenneth C. Hall. "A Time-Linearized Navier–Stokes Analysis of Stall Flutter." Journal of Turbomachinery 122, no. 3 (1999): 467–76. http://dx.doi.org/10.1115/1.1303073.

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A computational method for predicting unsteady viscous flow through two-dimensional cascades accurately and efficiently is presented. The method is intended to predict the onset of the aeroelastic phenomenon of stall flutter. In stall flutter, viscous effects significantly impact the aeroelastic stability of a cascade. In the present effort, the unsteady flow is modeled using a time-linearized Navier–Stokes analysis. Thus, the unsteady flow field is decomposed into a nonlinear spatially varying mean flow plus a small-perturbation harmonically varying unsteady flow. The resulting equations that govern the perturbation flow are linear, variable coefficient partial differential equations. These equations are discretized on a deforming, multiblock, computational mesh and solved using a finite-volume Lax–Wendroff integration scheme. Numerical modeling issues relevant to the development of the unsteady aerodynamic analysis, including turbulence modeling, are discussed. Results from the present method are compared to experimental stall flutter data, and to a nonlinear time-domain Navier–Stokes analysis. The results presented demonstrate the ability of the present time-linearized analysis to model accurately the unsteady aerodynamics associated with turbomachinery stall flutter. [S0889-504X(00)00203-8]
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9

Abdel-Rahim, A., F. Sisto, and S. Thangam. "Computational Study of Stall Flutter in Linear Cascades." Journal of Turbomachinery 115, no. 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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10

NISHIZAWA, Toshio, Yasuhiko IIDA, and Hiroyuki TAKATA. "Cascade Wind Tunnel Experiment of Stall Flutter." Transactions of the Japan Society of Mechanical Engineers Series B 65, no. 635 (1999): 2309–16. http://dx.doi.org/10.1299/kikaib.65.2309.

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Dissertations / Theses on the topic "Stall Flutter"

1

Forhad, Md Moinul Islam. "Robustness analysis for turbomachinery stall flutter." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4894.

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As compared with other robustness analysis tools, such as Hsubscript inf], the Mu analysis is less conservative and can handle both structured and unstructured perturbations. Finally, Genetic Algorithm is used as an optimization tool to find ideal parameters that will ensure best performance in terms of damping out flutter. Simulation results show that the procedure described in this thesis can be effective in studying the flutter stability margin and can be used to guide the gas turbine blade design.; Flutter is an aeroelastic instability phenomenon that can result either in serious damage or complete destruction of a gas turbine blade structure due to high cycle fatigue. Although 90% of potential high cycle fatigue occurrences are uncovered during engine development, the remaining 10% stand for one third of the total engine development costs. Field experience has shown that during the last decades as much as 46% of fighter aircrafts were not mission-capable in certain periods due to high cycle fatigue related mishaps. To assure a reliable and safe operation, potential for blade flutter must be eliminated from the turbomachinery stages. However, even the most computationally intensive higher order models of today are not able to predict flutter accurately. Moreover, there are uncertainties in the operational environment, and gas turbine parts degrade over time due to fouling, erosion and corrosion resulting in parametric uncertainties. Therefore, it is essential to design engines that are robust with respect to the possible uncertainties. In this thesis, the robustness of an axial compressor blade design is studied with respect to parametric uncertainties through the Mu analysis. The nominal flutter model is adopted from (9). This model was derived by matching a two dimensional incompressible flow field across the flexible rotor and the rigid stator. The aerodynamic load on the blade is derived via the control volume analysis. For use in the Mu analysis, first the model originally described by a set of partial differential equations is reduced to ordinary differential equations by the Fourier series based collocation method. After that, the nominal model is obtained by linearizing the achieved non-linear ordinary differential equations. The uncertainties coming from the modeling assumptions and imperfectly known parameters and coefficients are all modeled as parametric uncertainties through the Monte Carlo simulation.<br>ID: 030423207; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.)--University of Central Florida, 2011.; Includes bibliographical references (p. 44-47).<br>M.S.<br>Masters<br>Mechanical, Materials, and Aerospace Engineering<br>Engineering and Computer Science
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2

Clarkson, Jeffrey Dow. "A computational investigation of airfoil stall flutter." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23579.

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Dunn, Peter Earl. "Nonlinear stall flutter of wings with bending-torsion coupling." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/31028.

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Delamore-Sutcliffe, David William. "Modelling of unsteady stall aerodynamics and prediction of stall flutter boundaries for wings and propellers." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440048.

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Dunn, Peter Earl. "Stall flutter of graphite/epoxy wings with bending-torsion coupling." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/41240.

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Li, Jing. "Experimental investigation of the low speed stall flutter of an airfoil." Thesis, University of Manchester, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.488995.

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Stall flutter is a nonlinear aeroelastic phenomenon that can affect several types of aeroelastic systems such as helicopter rotor blades, wind turbine blades and highly flexible wings. While the related aerodynamic phenomenon of dynamic Stall has been the subject of many experimental studies, stall flutter itself has rarely been Investigated. This thesis presents a set of experiments conducted on a NACA 0012 airfoil undergoing stall flutter oscillations in a low speed wind tunnel.
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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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<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>Keywords: turbomachinery, flutter, forced response, gust,unsteady aerodynamics, Navier-Stokes equations, AdvectionUpstream Splitting Method, implicit scheme, non-reflectingboundary conditions, gust boundary conditions, parallelcomputing</p>
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Malher, Arnaud. "Amortisseurs passifs non linéaires pour le contrôle de l’instabilité de flottement". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLY010/document.

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Cette thèse est consacrée à l'étude d'amortisseurs passifs non linéaires innovants pour le contrôle de l'instabilité de flottement sur un profil d'aile à deux degrés de libertés. Lorsqu'un profil d'aile entre en flottement, il oscille de façon croissante jusqu'à se stabiliser sur un cycle limite dont l'amplitude peut être significative et détériorer sa structure. Le contrôle a ainsi deux objectifs principaux : retarder l'apparition de l'instabilité et réduire l'amplitude des cycles limites. Avant d'étudier l'influence des amortisseurs passifs, l'instabilité de flottement, et notamment le régime post-flottement, a été étudié. Une expérience de flottement sur une plaque plane a été menée et sa modélisation, prenant en compte le phénomène de décrochage dynamique, a été réalisée. Concernant le contrôle passif, le premier type d'amortisseur étudié est un amortisseur hystérétique réalisé à l'aide de ressorts en alliage à mémoire de forme. La caractéristique principale de tels amortisseurs est que leur force de rappel étant hystérétique, elle permet de dissiper une grande quantité d'énergie. L'objectif principal est ainsi de réduire l'amplitude des cycles limites provoqués par l'instabilité de flottement. Cet effet escompté a été observé et quantifié expérimentalement et numériquement à l'aide de modèles semi-empiriques. Le second type d'amortisseur utilisé est un amortisseur non linéaire de vibration accordé. Il est composé d'une petite masse connectée au profil d'aile à l'aide d'un ressort possédant une raideur linéaire et une raideur cubique. La partie linéaire de ce type d'amortisseur permet de retarder l'apparition de l'instabilité tandis que la partie non linéaire permet de réduire l'amplitude des cycles limites. L'influence de l'amortisseur non linéaire de vibration accordé a été étudiée analytiquement et numériquement. Il a été trouvé que l'apparition de l'instabilité est significativement retardée à l'aide de cet amortisseur, l'effet sur l'amplitude des cycles limites étant plus modeste<br>The aim of this thesis is to study the effect of passive nonlinear absorbers on the two degrees of freedom airfoil flutter. When an airfoil is subject to flutter instability, it oscillates increasingly until stabilizing on a limit cycle, the amplitude of which can be possibly substantial and thus damage the airfoil structure. The control has two main objectives : delay the instability and decrease the limit cycle amplitude. The flutter instability, and the post-flutter regime in particular, were studied first. A flutter experiment on a flat plate airfoil was conducted and the airfoil behavior was modeled, taking into account dynamic stall. Regarding the passive control, the first absorber studied was a hysteretic damper, realized using shape memory alloys springs. The characteristic of such dampers is their hysteretic restoring force, allowing them to dissipate a large amount of energy. Their main goal was thus to decrease the limit cycle amplitude caused by the flutter instability. This expected effect was observed and quantified both experimentally and numerically, using heuristic model. The second absorber studied was a nonlinear tuned vibration absorber. This absorber consists of a light mass attached to the airfoil through a spring having both a linear and a cubic stiffness. The role of the linear part of such absorber was to repel the instability threshold, while the aim of the nonlinear part was to decrease the limit cycle amplitude. It was found, analytically and numerically, that the instability threshold is substantially shifted by this absorber, whereas the limit cycle amplitude decrease is relatively modest
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Jha, Sourabh Kumar. "Stall Flutter of a Cascade of Blades at Low Reynolds Number." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/2865.

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Due to the requirements for high blade loading, modern turbo‐machine blades operate very close to the stall regime. This can lead to flow separation with periodic shedding of vortices, which could lead to self induced oscillations or stall flutter of the blades. Previous studies on stall flutter have focused on flows at high Reynolds number (Re ~ 106). The Reynolds numbers for fans/propellers of Micro Aerial Vehicles (MAVs), high altitude turbofans and small wind turbines are substantially lower (Re < 105). Aerodynamic characteristics of flows at such low Re is significantly different from those at high Re, due in part to the early separation of the flow and possible formation of laminar separation bubbles (LSB). The present study is targeted towards study of stall flutter in a cascade of blades at low Re. We experimentally study stall flutter of a cascade of symmetric NACA 0012 blades at low Reynolds number (Re ~ 30, 000) through forced sinusoidal pitching of the blades about mean angles of incidences close to stall. The experimental arrangement permits variations of the inter‐blade phase (σ) in addition to the oscillation frequency (f) and amplitude; the inter‐blade phase angle (σ) being the phase difference between the motions of adjacent blades in the cascade. The unsteady moments on the central blade in the cascade are directly measured, and used to calculate the energy transfer from the flow to the blade. This energy transfer is used to predict the propensity of the blades to undergo self‐induced oscillations or stall flutter. Experiments are also conducted on an isolated blade in addition to the cascade. A variety of parameters can influence stall flutter in a cascade, namely the oscillation frequency (f), the mean angle of incidence, and the inter‐blade phase angle (σ). The measurements show that there exists a range of reduced frequencies, k (=πfc/U, c being the chord length of the blade and U being the free stream velocity), where the energy transfer from the flow to the blade is positive, which indicates that the flow can excite the blade. Above and below this range, the energy transfer is negative indicating that blade excitations, if any, will get damped. This range of excitation is found to depend upon the mean angle of incidence, with shifts towards higher values of k as the mean angle of incidence increases. An important parameter for cascades, which is absent in the isolated blade case is the inter‐blade phase angle (σ). An excitation regime is observed only for σ values between ‐450 and 900, with the value of excitation being maximum for σ of 900. Time traces of the measured moment were found to be non‐sinusoidal in the excitation regime, whereas they appear to be sinusoidal in the damping regime. Stall flutter in a cascade has differences when compared with an isolated blade. For the cascade, the maximum value of excitation (positive energy transfer) is found to be an order of magnitude lower compared to the isolated blade case. Further, for similar values of mean incidence angle, the range of excitation is at lower reduced frequencies for a cascade when compared with an isolated blade. A comparison with un‐stalled or classical flutter in a cascade at high Re, shows that the inter‐blade phase angle is a major factor governing flutter in both cases. Some differences are observed as well, which appear to be due to stalled flow and low Re.
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Jha, Sourabh Kumar. "Stall Flutter of a Cascade of Blades at Low Reynolds Number." Thesis, 2013. http://hdl.handle.net/2005/2865.

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Due to the requirements for high blade loading, modern turbo‐machine blades operate very close to the stall regime. This can lead to flow separation with periodic shedding of vortices, which could lead to self induced oscillations or stall flutter of the blades. Previous studies on stall flutter have focused on flows at high Reynolds number (Re ~ 106). The Reynolds numbers for fans/propellers of Micro Aerial Vehicles (MAVs), high altitude turbofans and small wind turbines are substantially lower (Re < 105). Aerodynamic characteristics of flows at such low Re is significantly different from those at high Re, due in part to the early separation of the flow and possible formation of laminar separation bubbles (LSB). The present study is targeted towards study of stall flutter in a cascade of blades at low Re. We experimentally study stall flutter of a cascade of symmetric NACA 0012 blades at low Reynolds number (Re ~ 30, 000) through forced sinusoidal pitching of the blades about mean angles of incidences close to stall. The experimental arrangement permits variations of the inter‐blade phase (σ) in addition to the oscillation frequency (f) and amplitude; the inter‐blade phase angle (σ) being the phase difference between the motions of adjacent blades in the cascade. The unsteady moments on the central blade in the cascade are directly measured, and used to calculate the energy transfer from the flow to the blade. This energy transfer is used to predict the propensity of the blades to undergo self‐induced oscillations or stall flutter. Experiments are also conducted on an isolated blade in addition to the cascade. A variety of parameters can influence stall flutter in a cascade, namely the oscillation frequency (f), the mean angle of incidence, and the inter‐blade phase angle (σ). The measurements show that there exists a range of reduced frequencies, k (=πfc/U, c being the chord length of the blade and U being the free stream velocity), where the energy transfer from the flow to the blade is positive, which indicates that the flow can excite the blade. Above and below this range, the energy transfer is negative indicating that blade excitations, if any, will get damped. This range of excitation is found to depend upon the mean angle of incidence, with shifts towards higher values of k as the mean angle of incidence increases. An important parameter for cascades, which is absent in the isolated blade case is the inter‐blade phase angle (σ). An excitation regime is observed only for σ values between ‐450 and 900, with the value of excitation being maximum for σ of 900. Time traces of the measured moment were found to be non‐sinusoidal in the excitation regime, whereas they appear to be sinusoidal in the damping regime. Stall flutter in a cascade has differences when compared with an isolated blade. For the cascade, the maximum value of excitation (positive energy transfer) is found to be an order of magnitude lower compared to the isolated blade case. Further, for similar values of mean incidence angle, the range of excitation is at lower reduced frequencies for a cascade when compared with an isolated blade. A comparison with un‐stalled or classical flutter in a cascade at high Re, shows that the inter‐blade phase angle is a major factor governing flutter in both cases. Some differences are observed as well, which appear to be due to stalled flow and low Re.
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Books on the topic "Stall Flutter"

1

Clarkson, Jeffrey Dow. A computational investigation of airfoil stall flutter. Naval Postgraduate School, 1992.

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F, Ellison Joseph, and Dryden Flight Research Facility, eds. Flutter clearance of the Schweizer 1-36 deep-stall sailplane. National Aeronautics and Space Administration, Ames Research Center, Dryden Flight Research Facility, 1985.

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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. National Aeronautics and Space Administration, Scientific and Technical Information Division, 1989.

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Gann, Kyle. One Thing Follows the Next and I Just Do It. University of Illinois Press, 2017. http://dx.doi.org/10.5406/illinois/9780252035494.003.0008.

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This chapter outlines several more of Ashley's operas as well as a series of nonoperatic commissions made during the late 1980s and 1990s. The operas under discussion here are: Your Money My Life Goodbye (1998); Dust (1998); Celestial Excursions (2003); Concrete(2006–9); and Quicksand, which, as of this book's publication, is still under production. For his nonoperatic work, the chapter briefly examines: Superior Seven (1988), a flute concerto; Outcome Inevitable (1991), written for the Relache ensemble in Philadelphia; the piano piece Van Cao's Meditation (1992); and a wordless vocal piece with orchestra entitled Tract (1992). In addition, the chapter discusses his other recent commissions: When Famous Last Words Fail You (1997), Tap Dancing in the Sand (2004), and Hidden Similarities (2005).
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Book chapters on the topic "Stall Flutter"

1

Dowell, Earl H. "Stall Flutter." In A Modern Course in Aeroelasticity. Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09453-3_5.

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Crawley, Edward F., Howard C. Curtiss, David A. Peters, Robert H. Scanlan, and Fernando Sisto. "Stall flutter." In A Modern Course in Aeroelasticity. Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0499-9_5.

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Dowell, Earl H., Howard C. Curtiss, Robert H. Scanlan, and Fernando Sisto. "Stall flutter." In A modern course in aeroelasticity. Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-015-7858-5_5.

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Sisto, Fernando. "Stall Flutter." In A Modern Course in Aeroelasticity. Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-74236-2_5.

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Clarkson, J. D., J. A. Ekaterinaris, and M. F. Platzer. "Computational Investigation of Airfoil Stall Flutter." In Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines and Propellers. Springer New York, 1993. http://dx.doi.org/10.1007/978-1-4613-9341-2_21.

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Verstraelen, E., G. Kerschen, and G. Dimitriadis. "Internal Resonance and Stall Flutter Interactions in a Pitch-Flap Wing in the Wind-Tunnel." In Nonlinear Dynamics, Volume 1. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-15221-9_45.

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Wilkinson, Lynn R. "They Fluttered like Moths: Exile and Cosmopolitanism in the Work of Germaine de Staël and Georg Brandes." In Other Capitals of the Nineteenth Century. Palgrave Macmillan US, 2017. http://dx.doi.org/10.1057/978-1-137-57085-7_3.

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"Stall Flutter." In A Modern Course in Aeroelasticity. Springer Netherlands, 2005. http://dx.doi.org/10.1007/1-4020-2106-2_5.

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Eliot, George. "The Betrothal." In Adam Bede. Oxford University Press, 2008. http://dx.doi.org/10.1093/owc/9780199203475.003.0039.

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It was a dry Sunday, and really a pleasant day for the 2nd of November. There was no sunshine, but the clouds were high, and the wind was so still that the yellow leaves which fluttered down from the hedgerow elms must have fallen...
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Padeletti, Luigi, and Roberto De Ponti. "Atrial tachyarrhythmias in bradycardia–tachycardia syndrome: characterization and evolution." In ESC CardioMed, edited by Giuseppe Boriani. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198784906.003.0451.

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The association of sinus node disease and atrial tachyarrhythmias characterizes the bradycardia–tachycardia syndrome, which may result in an increased risk of heart failure, stroke, and death. Ageing and several cardiac and extracardiac diseases, which have the potential to affect both the atrial and the ventricular myocardium, can manifest their influence predominantly on the atria, leading to an atrial cardiomyopathy. In these cases, the same pathological process which leads to sinus node dysfunction can create a favourable substrate also for atrial tachyarrhythmias, which, if not present at the time of the initial diagnosis of the sinus node disease, can occur with an increasing prevalence during follow-up. In younger patients with no evident structural heart disease, a bradycardia–tachycardia syndrome may be the first clinical and unexpected manifestation of a still undiagnosed inherited genetic disease and therefore a specific diagnostic workup is necessary. In bradycardia–tachycardia syndrome, the most frequently encountered atrial tachyarrhythmia is atrial fibrillation, while typical atrial flutter is rarer. In peculiar subgroups of patients, other atrial tachyarrhythmias, such as atypical atrial flutter, macroreentrant or focal atrial tachycardia, may be present. In bradycardia–tachycardia syndrome, the evolution of atrial tachyarrhythmias clearly shows a worsening with an prevalence of associated atrial tachyarrhythmia over time. Pharmacological therapy for arrhythmias is of limited use, due to the concomitant sinus node dysfunction. The modality of pacing used to manage the sinus node disease has to be carefully chosen to minimize the evolution of atrial tachyarrhythmias. In fact, while ventricular pacing increases the incidence of atrial fibrillation and stroke, dual-chamber pacing with a specific algorithm for ventricular pacing minimization and prevention and treatment of atrial tachyarrhythmias reduces a composite endpoint of evolution to permanent atrial fibrillation, hospitalization, and death.
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Conference papers on the topic "Stall Flutter"

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Ekaterinaris, John A., and Max F. Platzer. "Numerical Investigation of Stall Flutter." In ASME 1994 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1994. http://dx.doi.org/10.1115/94-gt-206.

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Unsteady, separated, high Reynolds number flow over an airfoil undergoing oscillatory motion is investigated numerically. The compressible form of the Reynolds-averaged governing equations is solved using a high-order, upwind biased numerical scheme. The turbulent flow region is computed using a one-equation turbulence model. The computed results show that the key to the accurate prediction of the unsteady loads at stall flutter conditions is the modeling of the transitional flow region at the leading edge. A simplified criterion for the transition onset is used. The transitional flow region is computed with a modified form of the turbulence model. The computed solution, where the transitional flow region is included, shows that the small laminar/transitional separation bubble forming during the pitch-up motion has a decisive effect on the near wall flow and the development of the unsteady loads. Detailed comparisons of computed fully turbulent and transitional flow solutions with experimental data are presented.
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Forhad, Md M. I., Puneet Vishwakarma, and Yunjun Xu. "Mu Analysis for Turbomachinery Stall Flutter." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46624.

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Flutter is an aeroelastic instability phenomenon that can result either in serious damage or complete destruction of a gas turbine blade structure. To assure a reliable and safe operation, potential for blade flutter must be eliminated from the turbo-machinery stages. In this paper, the robustness of an axial compressor blade design is studied with respect to parametric uncertainties through the Mu analysis. The analytical description of the nominal model used is based on matching a two dimensional incompressible flow field across the flexible rotor and the rigid stator. The aerodynamic load on the blade is derived via the control volume analysis. For use in the Mu analysis, first the model originally described by a set of partial differential equations is reduced to ordinary differential equations by the Fourier series based collocation method. After that, the nominal model is obtained by linearizing the achieved non-linear ordinary differential equations. The uncertainties coming from the modeling assumptions, model reduction, and linearization approximations, as well as imperfectly known parameters and coefficients are all modeled as parametric uncertainties through the Monte Carlo simulation. As compared with other robustness analysis tools, such as Hinf, the Mu analysis is less conservative and can handle both structured and unstructured perturbations. Simulation results show that the procedure described in this paper can be effective in studying the flutter stability margin and can be used to guide the gas turbine blade design.
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Aotsuka, Mizuho, and Takeshi Murooka. "Numerical Analysis of Fan Transonic Stall Flutter." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26703.

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This paper describes numerical investigation of fan transonic stall flutter, especially focused on flutter bite. A transonic stall flutter occurs in high loaded condition at part rotating speed. A region of the transonic stall flutter occasionally protrudes to an operating line at narrow rotational speed range. This protrusion of flutter boundary is called flutter bite. In that case, it is necessary to re-design the blade for securing sufficient operating range. The re-design process might require some compromise on performance and/or weight, and takes long time. So it is important to understand the mechanism of the flutter bite. Two types of fan blade, one has a flutter bite and another dose not, are numerically studied with a 3D Navier Stokes CFD code. Numerical results show agreement with rig test results for the fans in qualitative sense. Detailed flow fields reveal that a detached shock wave and separation due to the shock boundary layer interaction play significant role for the flutter stability.
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Delamore-Sutcliffe, David, Richard Whiting, and Doug Greenwell. "Experimental and Numerical Study of Stall Flutter." In 23rd AIAA Applied Aerodynamics Conference. American Institute of Aeronautics and Astronautics, 2005. http://dx.doi.org/10.2514/6.2005-5096.

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Gkiolas, D., F. Mouzakis, and D. S. Mathioulakis. "Stall Flutter Measurements on a Rectangular Wing." In ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83162.

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The continuous development of wind turbine technology gradually leads to larger, more flexible blades with increasing aspect ratios and high tip speeds, while in everyday operation or extreme cases the blades experience stalled flow conditions. These aforementioned facts create the need for further study and physical understanding of stall induced vibrations – stall flutter. In this context an aeroelastic setup was constructed at the NTUA subsonic wind tunnel with a rigid rectangular wing (500 mm × 1400 mm) of a NACA 64-418 airfoil supported by a spring system that enables pitching and plunging motions. The elastic axis of the wing is located 35% of the chord far from the leading edge while its center of mass at 46%. Increasing the free stream velocity (up to Re = 670 000) under various initial static angles of attack, the wing was set at fluid induced oscillations (pitching and plunging). The response of the wing under these conditions was recorded employing two accelerometers and two wire sensors for both the rotational and linear wing displacements. At the same time, in the middle of the wing span thirty (30) fast responsive pressure transducers measured the pressure distribution along the chord, while strain gauges attached to the wing rotating shaft measured the applied unsteady aerodynamic loading. Based on the above simultaneously measured quantities various aspects of the aeroelastic instability of the examined wing were revealed.
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Culler, Ethan C., and John A. Farnsworth. "Pitch Rate Induced Separation Delay Modeling of Dynamic Stall and Stall Flutter." In AIAA Scitech 2019 Forum. American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-1394.

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Abdel-Rahim, A., F. Sisto, and S. Thangam. "Computational Study of Stall Flutter in Linear Cascades." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-005.

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Aeroelastic interaction in turbomachinery is of prime interest to operators, designers and aeroelasticians. 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°) 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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SISTO, F., S. THANGAM, and A. ABDEL-RAHIM. "Computational prediction of stall flutter in cascaded airfoils." In 31st Structures, Structural Dynamics and Materials Conference. American Institute of Aeronautics and Astronautics, 1990. http://dx.doi.org/10.2514/6.1990-1116.

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Haghighat, Sohrab, Zhiwei Sun, Hugh H. T. Liu та Junqiang Bai. "Robust Stall Flutter Suppression Using ℋ2/ℋ∞ Control". У ASME 2014 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/dscc2014-6337.

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Following the current trend in aeroelastic optimization, as wing structures have been made more flexible, active control systems such as flutter suppression systems have been widely adopted to reduce undesirable aeroelastic behaviors. The stability and the performance of flutter suppression control systems can be negatively affected as the inflow speed deviates from the nominal design value. In this work, a mixed-norm robust controller is designed to perform stall flutter suppression. A 2-dimensional nonlinear time-domain aeroservoelastic model is developed. The nonlinear equations are linearized at different flight conditions and are employed to construct an uncertainty model, which affects the nominal dynamics in an affine way. The obtained uncertain model of the aeroservoelastic system is used to design a mixed-norm H2/H∞ controller. The performance of the designed controller is compared with the performance of a non-robust H2 controller at different flight conditions. The proposed control architecture reduces the adverse effect of inflow speed variation on the performance of the closed-loop system.
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Dimitriadis, Grigorios, Damien Watrin, Tristan Perry, and Marilyn Smith. "Computational Considerations for the Prediction of Stall Flutter." In 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
20th AIAA/ASME/AHS Adaptive Structures Conference
14th AIAA. American Institute of Aeronautics and Astronautics, 2012. http://dx.doi.org/10.2514/6.2012-1706.

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Reports on the topic "Stall Flutter"

1

Kokotovic, Petar, Richard Murray, Arthur Krener, and James Paduano. Robust Nonlinear Control of Stall and Flutter in Aeroengines. Defense Technical Information Center, 2000. http://dx.doi.org/10.21236/ada387455.

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