Готові списки джерел за темами / Flutter Stability

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Автор: Grafiati
Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Flutter Stability"

1

Zhang, Cheng Long, Qiang Wang, Xiao Hui He, En Jiang Bian, and Jie He. "Study on a Flutter Stability Control Measure of Fabricated Steel Truss Bridge." Applied Mechanics and Materials 620 (August 2014): 7–13. http://dx.doi.org/10.4028/www.scientific.net/amm.620.7.

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Анотація:
Abstract. To improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting tuyere is put forward. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), with the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of tuyere is simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of origin and tuyere models are obtained. Through analysis, for the certain type fabricated steel truss bridge, the tuyere can improve its flutter stability. It illustrates the feasibility and reliability, and lays the foundation for further applied in practical projects.
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2

Tao, Shibo. "Suppression of Bridge Flutter Using Suction Control." Advances in Civil Engineering 2021 (November 27, 2021): 1–8. http://dx.doi.org/10.1155/2021/1788691.

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Анотація:
To verify the effectiveness of the suction-based method for improving flutter stability of long-span bridges, the forced vibration experiments for extracting the flutter derivatives of a section model with and without suction were performed, and the corresponding critical flutter wind speeds of this structure were calculated out. It is shown by the experiment that the flutter stability of the bridge depends on suction configuration. As the suction holes locate at the leeward side of the model, the critical flutter wind speed can attain maximum under the same suction velocity. In the analytical results, it is remarkably effective that the suction control improves the long-span bridge flutter stability.
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3

Gladwell, G. M. L. "Follower forces: Leipholz's early researches in elastic stability." Canadian Journal of Civil Engineering 17, no. 3 (June 1, 1990): 277–86. http://dx.doi.org/10.1139/l90-034.

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Анотація:
This paper provides an historical account of Leipholz's research into elastic stability. Emphasis is placed on divergence and flutter instability of follower force systems, the derivation of lower bounds for the critical load for divergence, and estimates for critical loads for flutter. Key words: elastic stability, divergence, flutter, lower bounds, nonconservative systems, symmetrisable matrix.
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4

Chen, Xingyu, Ruijie Hu, Haojun Tang, Yongle Li, Enbo Yu, and Lei Wang. "Flutter Stability of a Long-Span Suspension Bridge During Erection in Mountainous Areas." International Journal of Structural Stability and Dynamics 20, no. 09 (August 2020): 2050102. http://dx.doi.org/10.1142/s0219455420501023.

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Анотація:
In mountainous areas, more challenges are expected for the construction of long-span bridges. The flutter instability during erection is an outstanding issue due to flexible structural characteristics and strong winds with large angles of attack. Taking the suspension bridge as an example, the flutter stability of the bridge with different suspending sequences was investigated. First, the dynamic characteristics of the bridge during erection were computed by the finite element software ANSYS, along with the effects on flutter stability discussed. Then, different aerodynamic shapes of the bridge girder during erection were considered. The aerodynamic coefficients and the critical flutter state were determined by wind tunnel tests. Based on the above analysis, some structural measures are proposed for improving the flutter stability of the bridge during erection. The results show that the flutter stability of the bridge during erection is related to the suspending sequence and the aerodynamic shape of the girder. Owing to the structural dynamic characteristics, the bridge has better flutter stability when the girder segments are suspended symmetrically from the two towers to the mid-span. Considering the construction requirement that the bridge deck should be laid without intervals, this structural superiority is seriously weakened by the unfavorable aerodynamic shape of the girder. In order to improve the flutter stability of the bridge during erection, an effective way is to adopt some temporary structural strengthening measures.
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5

Xiaohui, He, Wang Qiang, Zhang Chenglong, Zhang Shunfeng, and Gao Yaming. "RESEARCH ON A FLUTTER STABILITY CONTROL MEASURE OF A FABRICATED STEEL TRUSS BRIDGE." Transactions of the Canadian Society for Mechanical Engineering 41, no. 2 (June 2017): 181–95. http://dx.doi.org/10.1139/tcsme-2017-1013.

Повний текст джерела
Анотація:
In order to improve the flutter stability of a certain type fabricated steel truss bridge, a method of setting guiding plates is proposed. Based on the two-dimensional 3 DOF coupling flutter method (2d-3DOF method), and by use of the numerical wind tunnel established by computational fluid dynamics (CFD), the flutter stability control measures of setting guiding plates are simulated. Through CFD numerical simulation, the flow field characteristics, flutter derivatives and critical flutter speed of original and guiding-plated models are obtained. It is found that for a certain type fabricated steel truss bridge, the guiding plates can improve its flutter stability. Thus, the feasibility and reliability of setting the guiding plates are proved, and the foundation for its further application in practical projects is laid.
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6

Gao, Hui, Feng Wang, Qinghai Guan, Huifang Hou, and Jiawu Li. "Research on the Flutter Stability of Bridge Sections Based on an Empirical Formula of an Aerostatic Three-Component Coefficient." Buildings 12, no. 8 (August 11, 2022): 1212. http://dx.doi.org/10.3390/buildings12081212.

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Анотація:
In order to study the relationship between an aerostatic three-component coefficient (ATCC) and bridge flutter and to quickly evaluate the flutter performance of bridges, we proposed a method based on the empirical formula of the ATCC. The correlation between the flutter driving term and the critical flutter wind speed V of nine bridges (six types of girder sections) was analyzed, and its rationality was verified using wind tunnel test results. The results showed that the flutter stability of the X-term damping-driven type, i.e., the slotted box girder, was the best; the flutter stability of the X + D-term damping-driven type, i.e., the H-shape bridge deck, was the worst; the flutter stability of D-term damping-driven type was measured as being between these two values. The gray correlation analysis method was used to analyze the correlation between the ATCC and the critical flutter wind speed. As well as the relationship between the ATCC and aerodynamic damping, an empirical parameter, K, based on the ATCC, was proposed for use in determining the D-term damping-driven flutter. The flutter stability of three types of girder sections was analyzed using parameter K, and the results of the analysis were consistent with the wind tunnel test results. The results show that the ATCC obtained from the segmental model force test can be used to preliminarily realize the rapid comparison and selection of flutter aerodynamic measures for bridges.
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7

Naumov, A. M. "Investigation of Additional Mass Effect on Dynamic Wing Model Stability in Airflow." Mechanical Engineering and Computer Science, no. 7 (October 11, 2019): 1–17. http://dx.doi.org/10.24108/0719.0001506.

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Анотація:
The paper investigates a dynamic stability of the wing model in the flow of incoming air. As is known, at a certain flow rate, called critical, there occurs a phenomenon of self-excited non-damping flexural-and-torsional self-vibrations, called flutters. The paper considers an anti-flutter approach that is the placement of additional weight on the elastic elements (springs) in the wing model. Thus, a three-stage wing model is under consideration while the publications concerning this problem more often describe a two-stage wing model. The paper is a natural sequel to the authors’ first paper [9] where a two-stage wing model was considered in detail. It continues and develops research in this area, conducted by many famous scientists, such as V.L. Biderman, S.P. Strelkov, Ya.G. Panovko, I.I. Gubanova, E.P. Grossman, J.C. Fyn and many others who have investigated this phenomenon. It is also necessary to mention the scientists, namely Keldysh M.V., Reese P.M., Parkhomovsky Y. M., etc. who not only studied this phenomenon, but developed anti-flutter methods for it.It should be noted that not only scientists-theoreticians, but also test pilots, in particular M.L. Gallay [8], contributed to the solution of the flutter problem. The paper describes in detail a derivation of the linear differential equations of small vibrations of a wing model with additional weight in the flow, determines the eigenfrequencies and forms of flexural-and-torsional vibrations, checks their orthogonality, explores the forced vibrations under aerodynamic force and moment, and estimates a critical flow rate for a number of system parameters, namely a mass of the additional weight and the rigidity of its suspension. The conclusion is drawn that these parameters effect on the critical rate. Based on the calculation results, one can come to the conclusion on the additional weight effect on the critical flutter speed and on how relevant the anti-flutter method is. The given paper may be of interest both for students of technical specialties who learn the theory of mechanical vibrations, and for engineers majoring in aero-elasticity and dynamic stability of the elements of mechanical systems.
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8

Yang, Yan, and Hu Yong Li. "Analysis on the Flutter Stability of Span Overpass." Applied Mechanics and Materials 246-247 (December 2012): 532–36. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.532.

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Анотація:
The span overpass anti-flutter stability has been the focus of our study. Large span overpass in the running state of the wind and the load in line with the stability has been the concern and attention of the engineering and technical personnel. This paper establishes a flexible dynamics model through the use of long-span overpass line finite element analysis. Moreover, after the flutter stability of qualitative terms, we have a number of effective methods and measures to increase the flutter stability of the large-span overpass.
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9

Koch, Christopher. "Parametric whirl flutter study using different modelling approaches." CEAS Aeronautical Journal 13, no. 1 (October 6, 2021): 57–67. http://dx.doi.org/10.1007/s13272-021-00548-0.

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Анотація:
AbstractThis paper demonstrates the importance of assessing the whirl flutter stability of propeller configurations with a detailed aeroelastic model instead of local pylon models. Especially with the growing use of electric motors for propulsion in air taxis and commuter aircraft whirl flutter becomes an important mode of instability. These configurations often include propeller which are powered by lightweight electric motors and located at remote locations, e.g. the wing tip. This gives rise to an aeroelastic instability called whirl flutter, involving the gyroscopic whirl modes of the engine. The driving parameters for this instability are the dynamics of the mounting structure. Using a generic whirl flutter model of a propeller at the tip of a lifting surface, parameter studies on the flutter stability are carried out. The aeroelastic model consists of a dynamic MSC.Nastran beam model coupled with the unsteady ZAERO ZONA6 aerodynamic model and strip theory for the propeller aerodynamics. The parameter studies focus on the influence of different substructures (ranging from local engine mount stiffness to global aircraft dynamics) on the aeroelastic stability of the propeller. The results show a strong influence of the level of detail of the aeroelastic model on the flutter behaviour. The coupling with the lifting surface is of major importance, as it can stabilise the whirl flutter mode. Including wing unsteady aerodynamics into the analysis can also change the whirl flutter behaviour. This stresses the importance of including whirl flutter in the aeroelastic stability analysis on aircraft level.
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10

Guo, Junjie, Haojun Tang, Yongle Li, Lianhuo Wu, and Zewen Wang. "Optimization for vertical stabilizers on flutter stability of streamlined box girders with mountainous environment." Advances in Structural Engineering 23, no. 2 (August 7, 2019): 205–18. http://dx.doi.org/10.1177/1369433219868077.

Повний текст джерела
Анотація:
Wind environment in mountainous areas is very different from that in coastal and plain areas. Strong winds always show large angles of attack, affecting the flutter stability of long-span bridges which is one of the most important design factors. The central vertical stabilizer has been demonstrated to be an effective aerodynamic measure to improve the flutter stability, and this article optimizes the stabilizer to improve its applicability in mountainous areas. Computational fluid dynamics simulations are first performed to analyze the effects of stabilizers with different positions and forms on the flutter stability of an ideal box girder, and the aerodynamic mechanism is discussed based on the static and the dynamic flow fields, respectively. Wind tunnel tests are then carried out to test the critical flutter wind speed of a real box girder equipped with different stabilizers, and the change in its flutter stability is further analyzed. The results show that the vertical stabilizer with appropriate positions and heights can improve the participation level of structural heaving vibration, and thereby increases the flutter stability. At large angles of attack, the big vortex on the leading edge which may drive the bridge to flutter instability is gradually weakened with the increase in stabilizer’s height. Compared with a single stabilizer, double vertical stabilizers, in the midst of which exists a negative pressure region, could achieve better effects.
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Дисертації з теми "Flutter Stability"

1

Yildiz, Erdinc Nuri. "Aeroelastic Stability Prediction Using Flutter Flight Test Data." Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608623/index.pdf.

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Анотація:
Flutter analyses and tests are the major items in flight certification efforts required when a new air vehicle is developed or when a new external store is developed for an existing aircraft. The flight envelope of a new aircraft as well as the influence of aircraft modifications on an existing flight envelope can be safely determined only by flutter tests. In such tests, the aircraft is instrumented by accelerometers and exciters. Vibrations of the aircraft at specific dynamic pressures are measured and transmitted to a ground station via telemetry systems during flutter tests. These vibration data are analyzed online by using a flutter test software with various methods implemented in order to predict the safety margin with respect to flutter. Tests are performed at incrementally increasing dynamic pressures and safety regions of the flight envelope are determined step by step. Since flutter is a very destructive instability, tests are performed without getting too close to the flutter speed and estimations are performed by extrapolation. In this study, pretest analyses and flutter prediction methods that can be used in various flight conditions are investigated. Existing methods are improved and their applications are demonstrated with experiments. A novel method to predict limit cycle oscillations that are encountered in some modern fighter aircraft is developed. The prediction method developed in this study can effectively be used in cases where the nonlinearities in aircraft dynamics and air flow reduce the applicability of the classical prediction methods. Some further methods to reduce the adverse effects of these nonlinearities on the predictions are also developed.
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2

Li, Rui. "NUMERICAL INVESTIGATION OF THE INFLUENCE OF FRONT CAMBER ON THE STABILITY OF A COMPRESSOR AIRFOIL." UKnowledge, 2005. http://uknowledge.uky.edu/gradschool_theses/345.

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Анотація:
With the advent of smart materials it is becoming possible to alter the structural characteristics of turbomachine airfoils. This change in structural characteristics can include, but is not limited to, changes in the shape (morphing) of the airfoil. Through changes in the airfoil shape, aerodynamic performance can be improved. Moreover, this technique has the potential to act as a flutter suppressant. In this investigation changes in the airfoil front camber while maintaining the airfoil thickness distribution are made to increase airfoil stability. The airfoil section is representative of current low aspect ratio fan blade tip sections. To assess the influence of the change in airfoil shape on stability the work-per-cycle was evaluated for torsion mode oscillations around the mid-chord at an inlet Mach number of 0.5 with an interblade phase angle of 180 degree Cchordal incidence angles of both 0 degree and 10 degree, and a reduced frequency of 0.4.
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3

Patruno, Luca <1986&gt. "Aeroelastic stability of structures: flutter analysis using Computational Fluid Dynamics." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6616/1/Patruno_Luca_tesi.pdf.

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Анотація:
Thanks to the increasing slenderness and lightness allowed by new construction techniques and materials, the effects of wind on structures became in the last decades a research field of great importance in Civil Engineering. Thanks to the advances in computers power, the numerical simulation of wind tunnel tests has became a valid complementary activity and an attractive alternative for the future. Due to its flexibility, during the last years, the computational approach gained importance with respect to the traditional experimental investigation. However, still today, the computational approach to fluid-structure interaction problems is not as widely adopted as it could be expected. The main reason for this lies in the difficulties encountered in the numerical simulation of the turbulent, unsteady flow conditions generally encountered around bluff bodies. This thesis aims at providing a guide to the numerical simulation of bridge deck aerodynamic and aeroelastic behaviour describing in detail the simulation strategies and setting guidelines useful for the interpretation of the results.
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4

Patruno, Luca <1986&gt. "Aeroelastic stability of structures: flutter analysis using Computational Fluid Dynamics." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6616/.

Повний текст джерела
Анотація:
Thanks to the increasing slenderness and lightness allowed by new construction techniques and materials, the effects of wind on structures became in the last decades a research field of great importance in Civil Engineering. Thanks to the advances in computers power, the numerical simulation of wind tunnel tests has became a valid complementary activity and an attractive alternative for the future. Due to its flexibility, during the last years, the computational approach gained importance with respect to the traditional experimental investigation. However, still today, the computational approach to fluid-structure interaction problems is not as widely adopted as it could be expected. The main reason for this lies in the difficulties encountered in the numerical simulation of the turbulent, unsteady flow conditions generally encountered around bluff bodies. This thesis aims at providing a guide to the numerical simulation of bridge deck aerodynamic and aeroelastic behaviour describing in detail the simulation strategies and setting guidelines useful for the interpretation of the results.
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5

Gade, Prasad V. N. "Performance Enhancement and Stability Robustness of Wing/Store Flutter Suppression System." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30339.

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Анотація:
In recent years, combat aircraft with external stores have experienced a decrease in their mission capabilities due to lack of robustness of the current passive wing/store flutter suppression system to both structured as well as unstructured uncertainties. The research program proposed here is to investigate the feasibility of using a piezoceramic wafer actuator for active control of store flutter with the goal of producing a robust feedback system that demonstrates increased performance as well as robustness to modeling errors. This approach treats the actuator as an active soft-decoupling tie between the wing and store, thus isolating the wing from store pitch inertia effects. Advanced control techniques are used to assess the nominal performance and robustness of wing/store system to flutter critical uncertainties. NOTE: (10/2009) An updated copy of this ETD was added after there were patron reports of problems with the file.
Ph. D.
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6

Zhuang, Qingyuan. "Parametric Study on the Aeroelastic Stability of Rotor Seals." Thesis, KTH, Kraft- och värmeteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116689.

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Анотація:
Labyrinth seals are widely used in rotating machinery and have been shown to experience aeroelastic instabilities. The rapid development of computational fluid dynamics now provides a high fidelity approach for predicting the aeroelastic behavior of labyrinth seals in three dimension and exhibits great potential within industrial application, especially during the detailed design stages. In the current publication a time-marching unsteady Reynolds- averaged Navier-Stokes solver was employed to study the various historically identified parameters that have essential influence on the stability of labyrinth seals. Advances in understanding of the related aeroelastic (flutter) phenomenon were achieved based on extensive yet economical numerical analysis of a simplified seal model. Further, application of the same methodology to several realistic gas turbine labyrinth seal designs confirmed the perceived knowledge and received agreements from experimental indications. Abbott’s criteria in describing the labyrinth seal aeroelastic behaviors were reaffirmed and further developed.
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7

Nibbelink, Bruce D. "Finite-state inflow applied to aeroelastic flutter or fixed and rotating wings." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/13287.

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8

Kvamstad, Tori Høyland. "Assessment of the flutter stability limit of the Hålogaland Bridge using aprobabilistic approach." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16048.

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Анотація:
The present work is a study of the aeroelastic stability limit of the Hålogaland Bridge. The state-of-the-art theory concerning determination of flutter stability limits in modern bridge design is presented. The self-excited loads are modeled using aerodynamic derivatives obtained in a free vibration wind tunnel test of a section model. The bimodal flutter limit of all relevant mode pairs are evaluated, by considering frequency separation and mode shape similarity of the respective modes. The findings of the bimodal analysis are used as a starting point in the assessment of the multimodal flutter limit. The governing flutter mechanism of the Hålogaland Bridge is three-mode flutter, where the fundamental symmetric torsion mode couple with the first and second symmetric vertical modes. The critical mean wind velocity is found to 68.1 m/s, which is above the design requirement of 60.2m/s. The critical oscillation frequency is found to 2.03 rad/s. The development of the total damping in the system with respect to increasing mean wind velocity is evaluated. Horizontal mode influence is investigated by applying quasi-static theory and aerodynamic derivatives obtained in the discrete vortex shedding software DVMFLOW. The results indicate that horizontal modes do not have influence on the flutter limit. Modeling uncertainty in the prediction of flutter limits is discussed. A proposed probabilistic flutter analysis utilizing Monte Carlo simulations is used to evaluate the effect of parameter uncertainty. The sensitivity with respect to parameter uncertainty of flutter derivatives and structural damping is assessed by considering the probability distribution of the flutter limit. Including uncertainties of the flutter derivatives due to different interpretation of scatter in the wind tunnel test series is found to have a significant influence on the flutter limit.Large scatter resulted in wide distributions. Choice of structural damping ratio is seen to have little influence. The distribution of critical flutter velocity maybe modeled by an extreme value distribution, where a 99 % confidence interval ranges from 63.5 m/s to 78.6 m/s. The results indicate that the proposed probabilisticflutter analysis provides extended information concerning the accuracy in the prediction of flutter limits.
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9

Cal, Anthony Angelo. "A unified approach to flutter, dynamic stability and response analysis of high aspect ratio aircraft." Thesis, City University London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317968.

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10

Sun, Tianrui. "Improved Flutter Prediction for Turbomachinery Blades with Tip Clearance Flows." Licentiate thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233770.

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Анотація:
Recent design trends in steam turbines strive for high aerodynamic loading and high aspect ratio to meet the demand of higher efficiency. These design trends together with the low structural frequency in last stage steam turbines increase the susceptibility of the turbine blades to flutter. Flutter is the self-excited and self-sustained aeroelastic instability phenomenon, which can result in rapid growth of blade vibration amplitude and eventually blade failure in a short period of time unless adequately damped. To prevent the occurrences of flutter before the operation of new steam turbines, a compromise between aeroelastic stability and stage efficiency has to be made in the steam turbine design process. Due to the high uncertainty in present flutter prediction methods, engineers use large safety margins in predicting flutter which can rule out designs with higher efficiency. The ability to predict flutter more accurately will allow engineers to push the design envelope with greater confidence and possibly create more efficient steam turbines. The present work aims to investigate the influence of tip clearance flow on the prediction of steam turbine flutter characteristics. Tip clearance flow effect is one of the critical factors in flutter analysis for the majority of aerodynamic work is done near the blade tip. Analysis of the impact of tip clearance flow on steam turbine flutter characteristics is therefore needed to formulate a more accurate aeroelastic stability prediction method in the design phase.Besides the tip leakage vortex, the induced vortices in the tip clearance flow can also influence blade flutter characteristics. However, the spatial distribution of the induced vortices cannot be resolved by URANS method for the limitation of turbulence models. The Detached-Eddy Simulation (DES) calculation is thus applied on a realistic-scale last stage steam turbine model to analyze the structure of induced vortices in the tip region. The influence of the tip leakage vortex and the induced vortices on flutter prediction are analyzed separately. The KTH Steam Turbine Flutter Test Case is used in the flutter analysis as a typical realistic-scale last stage steam turbine model. The energy method based on 3D unsteady CFD calculation is applied in the flutter analysis. Two CFD solvers, an in-house code LUFT and a commercial software ANSYS CFX, are used in the flutter analysis as verification of each other. The influence of tip leakage vortex on the steam turbine flutter prediction is analyzed by comparing the aeroelastic stability of two models: one with the tip gap and the other without the tip gap. Comparison between the flutter characteristics predicted by URANS and DES approaches is analyzed to investigate the influence of the induced vortices on blade flutter characteristics. The multiple induced vortices and their relative rotation around the tip leakage vortex in the KTH Steam Turbine Flutter Test Case are resolved by DES but not by URANS simulations. Both tip leakage vortex and induced vortices have an influence on blade loading on the rear half of the suction side near the blade tip. The flutter analysis results suggest that the tip clearance flow has a significant influence on blade aerodynamic damping at the least stable interblade phase angle (IBPA), while its influence on the overall shape of the damping curve is minor. At the least stable IBPA, the tip leakage vortex shows a stabilization effect on rotor aeroelastic stabilities while the induced vortices show a destabilization effect on it. Meanwhile, a non-linear unsteady flow behavior is observed due to the streamwise motion of induced vortices during blade oscillation, which phenomenon is only resolved in DES results.
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Книги з теми "Flutter Stability"

1

Woods, Jessica A. Results of a parametric aeroelastic stability analysis of a generic x-wing aircraft. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1989.

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2

NASA Dryden Flight Research Center., ed. A historical overview of flight flutter testing. [Washington, D.C.]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Program, 1995.

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3

1945-, Bennett Robert M., and Langley Research Center, eds. Using transonic small disturbance theory for predicting the aeroelastic stability of a flexible wind-tunnel model. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1990.

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4

United States. National Aeronautics and Space Administration, ed. Unstalled flutter stability predictions and comparisions [sic] to test data for a composite prop-fan model. [Windsor Locks, CT]: Hamilton Standard Division, United Technologies Corp., 1986.

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5

United States. National Aeronautics and Space Administration., ed. Unstalled flutter stability predictions and comparisions [sic] to test data for a composite prop-fan model. [Windsor Locks, CT]: Hamilton Standard Division, United Technologies Corp., 1986.

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6

United States. National Aeronautics and Space Administration., ed. FPCAS3D user's guide: Full potential aeroelastic program. [Washington, DC]: National Aeronautics and Space Administration, 1995.

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7

United States. National Aeronautics and Space Administration., ed. FPCAS3D user's guide: Full potential aeroelastic program. [Washington, DC]: National Aeronautics and Space Administration, 1995.

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8

United States. National Aeronautics and Space Administration., ed. Alleviation of whirl-flutter on a joined-wing tilt-rotor aircraft configuration using active controls. [Alexandria, Va.]: American Helicopter Society, 1991.

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9

Nissim, E. Effect of control surface mass unbalance on the stability of a closed-loop active control system. [Washington, DC]: National Aeronautics and Space Administration, Office of Management, Scientific and Technical Information Division, 1989.

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10

Borri, Claudio, and Claudio Mannini, eds. Aeroelastic Phenomena and Pedestrian-Structure Dynamic Interaction on Non-Conventional Bridges and Footbridges. Florence: Firenze University Press, 2010. http://dx.doi.org/10.36253/978-88-6453-202-8.

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Fluid-structure and pedestrian-structure interaction phenomena are extremely important for non-conventional bridges. The results presented in this volume concern: simplified formulas for flutter assessment; innovative structural solutions to increase the aeroelastic stability of long-span bridges; numerical simulations of the flow around a benchmark rectangular cylinder; examples of designs of large structures assisted by wind-tunnel tests; analytical, computational and experimental investigation of the synchronisation mechanisms between pedestrians and footbridge structures. The present book is addressed to a wide audience including professionals, doctoral students and researchers, aiming to increase their know-how in the field of wind engineering, bluff-body aerodynamics and bridge dynamics.
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Частини книг з теми "Flutter Stability"

1

Lind, Rick, and Marty Brenner. "Robust Flutter Margins of the F/A-18 SRA." In Robust Aeroservoelastic Stability Analysis, 153–71. London: Springer London, 1999. http://dx.doi.org/10.1007/978-1-4471-0849-8_11.

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2

Bigoni, Davide. "Flutter from Friction in Solids and Structures." In Dynamic Stability and Bifurcation in Nonconservative Mechanics, 1–61. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-93722-9_1.

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3

Mougel, Jérôme, and Sébastien Michelin. "Flag Flutter Close to a Free Surface: A Local Stability Analysis." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 173–86. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55594-8_17.

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4

Kemme, Ralf, Gerhard Kahl, and Stefan Schmitt. "Flutter Stability of a Transonic Compressor Rotor - Application and Comparison of Different Numerical Methods." In Notes on Numerical Fluid Mechanics and Multidisciplinary Design, 448–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-39604-8_56.

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5

Kim, Dong Hyun, and Il Kwon Oh. "Lamination Optimization of Composite Curved Wing for Maximum Flutter Stability Using Micro Genetic Algorithm." In Fracture and Damage Mechanics V, 743–46. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-413-8.743.

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6

Lerbet, Jean, Noël Challamel, François Nicot, and Félix Darve. "Flutter Kinematic Structural Stability." In Stability of Discrete Non-conservative Systems, 125–56. Elsevier, 2020. http://dx.doi.org/10.1016/b978-1-78548-286-1.50005-x.

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7

Georgiou, Georgia, Hamed Haddad Khodaparast, and Jonathan E. Cooper. "Uncertainty Quantification of Aeroelastic Stability." In Advances in Computational Intelligence and Robotics, 329–56. IGI Global, 2014. http://dx.doi.org/10.4018/978-1-4666-4991-0.ch016.

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The application of uncertainty analysis for the prediction of aeroelastic stability, using probabilistic and non-probabilistic methodologies, is considered in this chapter. Initially, a background to aeroelasticity and possible instabilities, in particular “flutter,” that can occur in aircraft is given along with the consideration of why Uncertainty Quantification (UQ) is becoming an important issue to the aerospace industry. The Polynomial Chaos Expansion method and the Fuzzy Analysis for UQ are then introduced and a range of different random and quasi-random sampling techniques as well as methods for surrogate modeling are discussed. The implementation of these methods is demonstrated for the prediction of the effects that variations in the structural mass, resembling variations in the fuel load, have on the aeroelastic behavior of the Semi-Span Super-Sonic Transport wind-tunnel model (S4T). A numerical model of the aircraft is investigated using an eigenvalue analysis and a series of linear flutter analyses for a range of subsonic and supersonic speeds. It is shown how the Probability Density Functions (PDF) of the resulting critical flutter speeds can be determined efficiently using both UQ approaches and how the membership functions of the aeroelastic system outputs can be obtained accurately using a Kriging predictor.
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8

Čečrdle, Jiří. "Aeroelastic Stability of Turboprop Aircraft: Whirl Flutter." In Flight Physics - Models, Techniques and Technologies. InTech, 2018. http://dx.doi.org/10.5772/intechopen.70171.

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9

"10 Campbell diagrams of gyroscopic continua and subcritical friction-induced flutter." In Nonconservative Stability Problems of Modern Physics, 342–76. De Gruyter, 2021. http://dx.doi.org/10.1515/9783110655407-012.

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10

"Chapter 10: Campbell diagrams of gyroscopic continua and subcritical friction-induced flutter." In Nonconservative Stability Problems of Modern Physics, 294–328. De Gruyter, 2013. http://dx.doi.org/10.1515/9783110270433.294.

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Тези доповідей конференцій з теми "Flutter Stability"

1

Fang, Mingchang, and Yanrong Wang. "Aeroelastic Stability of Axial Compressor Blades Under Different Operating Conditions." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14758.

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Abstract Flutter is one of the important issues in turbomachinery analysis. There are four common types of flutter, including sub/transonic stall flutter, choke flutter, supersonic stall flutter, and supersonic non-stall flutter. Flutter may occur under many different operating conditions. Therefore, it is important to study the aeroelastic stability of blades when the compressor operates under different conditions. Based on the energy method proposed by Carta [1], this paper studied the aeroelastic stability of the second-stage rotor blade of an axial compressor under different operating conditions. It is found that the aerodynamic damping of the blade under the near-stall operating point of the compressor is negative. Three typical operating points are selected to study the differences in flutter mechanism between different operating conditions. The 90% span section is selected as the reference section to analyze the variation of the aerodynamic work at different operating points. The influence of reduced frequency, modal component, and tip clearance on aerodynamic damping are analyzed under three operating points.
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2

Kang, Hao, Hyeonsoo Yeo, Jinwei Shen, Andrew Kreshock, Robert Thornburgh, and Matthew Floros. "Correlation of Tiltrotor Aeroelastic Stability Wind Tunnel Test." In Vertical Flight Society 79th Annual Forum & Technology Display. The Vertical Flight Society, 2023. http://dx.doi.org/10.4050/f-0079-2023-18047.

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This paper presents a correlation study of detailed finite element modeling with component vibration tests and comprehensive analysis modeling with whirl flutter experimental data for the TiltRotor Aeroelastic Stability Testbed (TRAST). TRAST is a semi-span tiltrotor model system that has been developed to investigate tiltrotor whirl flutter phenomena and to provide experimental data for rotorcraft analysis validations. Two comprehensive rotorcraft analysis codes, CAMRAD II and RCAS, were used for the whirl flutter correlation study. To ensure that real structures are represented accurately by the comprehensive analysis codes, detailed NASTRAN models using 2D/3D shell and solid elements were developed and refined based on vibration tests of the TRAST components. The 2D/3D NASTRAN model was simplified to a 1-D model consisting solely of beam and other 1-D elements. Using the components and the properties of the 1-D model, structural models for the comprehensive analyses were developed and validated against the vibration test data. Models for whirl flutter analysis were developed based on the validated structural models and compared to the whirl flutter experimental data. Sensitivity of the TRAST whirl flutter prediction to modeling details is discussed.
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3

Kreshock, Andrew R., and Hyeonsoo Yeo. "Tiltrotor Whirl-Flutter Stability Predictions using Comprehensive Analysis." In 58th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2017. http://dx.doi.org/10.2514/6.2017-0639.

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4

Breard, C., M. Imregun, A. Sayma, and M. Vahdati. "Flutter stability analysis of a complete fan assembly." In 37th Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1999. http://dx.doi.org/10.2514/6.1999-238.

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5

Jia, Xinkai, Huang Huang, and Dingxi Wang. "Effect of Fan Blade Vibration Mode on Flutter Stability." In GPPS Xi'an21. GPPS, 2022. http://dx.doi.org/10.33737/gpps21-tc-182.

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The fan blade vibration mode shape has a critical influence on its flutter stability, which could result in potentially disastrous consequences. A numerical study of the effects of vibration mode shape on the fan blade flutter is presented. The first bending mode of a fan blade is decomposed into three fundamental modes: a chord wise plunge motion, a flap wise plunge motion and a twist motion. The aerodynamic works arising from the decomposed three fundamental modes, with the original natural frequency unchanged, are computed by the influence coefficient method, and the least stable fundamental mode as well as the least stable nodal diameter are assessed. In addition, the effect of vibration frequency on flutter stability is also investigated for the three decomposed modes.
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6

Naeini, Saeid Fadaei, Abbas Mazidi, Fred F. Afagh, and Robert G. Langlois. "Flutter Stability Analysis of Parked Floating Wind Turbine Blades." In Canadian Society for Mechanical Engineering International Congress (2020 : Charlottetown, PE). Charlottetown, P.E.I.: University of Prince Edward Island. Robertson Library, 2020. http://dx.doi.org/10.32393/csme.2020.1238.

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7

Roizner, Federico, and Moti Karpel. "Sensitivity of Aeroservoelastic Stability Characteristics Using Parametric Flutter Margins." In AIAA Scitech 2019 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2019. http://dx.doi.org/10.2514/6.2019-1213.

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8

Koch, Christopher, and Benedikt Koert. "Influence of blade elasticity on propeller whirl flutter stability." In AIAA SCITECH 2023 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2023. http://dx.doi.org/10.2514/6.2023-1307.

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9

Lee, Sang Hyeon, Ho-Kyung Kim, and Youchan Hwang. "Flutter Behavior and Stability Evaluation of Suspended Footbridge through Wind Tunnel Experiments and Aeroelastic Flutter Analysis." In IABSE Congress, Nanjing 2022: Bridges and Structures: Connection, Integration and Harmonisation. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2022. http://dx.doi.org/10.2749/nanjing.2022.1873.

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<p>Suspended footbridges are set apart by being much more lightweight and slender compared to conventional highway bridges. For this reason, the stiffness and damping of the bridge system are significantly lower, causing an outsized influence of wind load. Therefore, a precise evaluation must be performed to secure the wind stability of the suspended footbridge. However, design specifications are not documented, and reported studies are insufficient. In this study, a conventional 2-DOF section model test was conducted to estimate the flutter wind velocity of the suspended footbridge and observe the flutter behavior. Frequency domain step-by-step flutter analysis was performed to identify the flutter generation mechanism of examined suspended footbridge. It was deduced that the decrease of torsional damping due to the torsional-driven vertical vibration and coupled aeroelastic force induced the torsional flutter.</p>
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10

Kreshock, Andrew, Dagid Piatak, Robert Thornburgh, Matthew Wilbur, Hao Kang, and Martin Sekula. "Initial Whirl-Flutter Characterization of the TiltRotor Aeroelastic Stability Testbed." In Vertical Flight Society 79th Annual Forum & Technology Display. The Vertical Flight Society, 2023. http://dx.doi.org/10.4050/f-0079-2023-18037.

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This paper discusses the initial wind tunnel test of the TiltRotor Aeroelastic Stability Testbed (TRAST). TRAST is a generic tiltrotor testbed developed in collaboration between NASA and the Army. Ultimately, this test was a checkout of the model systems, functionality and familiarization, but also obtained subcritical whirl-flutter data in the terms of frequency and damping. Flutter data include two main configurations with different pitch spring stiffness, referred to as 4k and 8k, that were tested at various rotor speeds and airspeeds at the NASA Langley Transonic Dynamics Tunnel. The test included two modes of drivetrain operation: powered and windmilling. However, powered mode of operation was only conducted with the 8k pitch spring. This test reinforced the traditional knowledge of whirl-flutter trends such as flutter speed would decrease with an increase in rotor speed. The critical mode consistently being the wing vertical bending mode. The chord mode as expected was not affected by the pitch spring and was likely to go unstable at a tunnel airspeed slightly beyond the wing vertical bending mode. There were also test specific challenges such as the TRAST modal damping was more sensitive to temperature and amplitude motor than was expected. This test gathered valuable data on the baseline characterization of TRAST, how to improve the model and test practices for future wind tunnel testing. Additionally, a new more automated method for experimental subcritical damping determination based on the Stockwell transform has been demonstrated that may lead to more consistent whirl-flutter stability boundaries.
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