A numerical method to simulate the coupled oscillations of flexible structures in flowing fluids

Wang, Siying; Yin, Xiaohong

doi:10.1007/s11434-010-4195-z

Cited by 13 publications

(11 citation statements)

References 31 publications

(41 reference statements)

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“…The fluid is assumed to be inviscid and incompressible, and a panel method is used to calculate the pressure on the flag (Tang and Paï doussis, 2007;Wang and Yin, 2010). As shown in Fig.…”

Section: Calculation Of the Pressure Differencementioning

confidence: 99%

Bifurcation and chaos of a flag in an inviscid flow

Chen

Jia

et al. 2014

Journal of Fluids and Structures

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A two-dimensional model is developed to study the flutter instability of a flag immersed in an inviscid flow. Two dimensionless parameters governing the system are the structure-to-fluid mass ratio M * and the dimensionless incoming flow velocity U * . A transition from a static steady state to a chaotic state is investigated at a fixed M * =1 with increasing U * . Five single-frequency periodic flapping states are identified along the route, including four symmetrical oscillation states and one asymmetrical oscillation state. For the symmetrical states, the oscillation frequency increases with the increase of U * , and the drag force on the flag changes linearly with the Strouhal number. Chaotic states are observed when U * is relatively large. Three chaotic windows are observed along the route. In addition, the system transitions from one periodic state to another through either period-doubling bifurcations or quasi-periodic bifurcations, and it transitions from a periodic state to a chaotic state through quasi-periodic bifurcations.

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“…The fluid is assumed to be inviscid and incompressible, and a panel method is used to calculate the pressure on the flag (Tang and Paï doussis, 2007;Wang and Yin, 2010). As shown in Fig.…”

Section: Calculation Of the Pressure Differencementioning

confidence: 99%

Bifurcation and chaos of a flag in an inviscid flow

Chen

Jia

et al. 2014

Journal of Fluids and Structures

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“…There are close links between the components of a wind turbine. This is related to many optimization objectives such as the maximum power output of the rotor, minimum cost of electricity (COE), and minimum tower thrust, as well as meeting the constraints of control, noise and manufacturing [1][2][3][4][5]. Because of its complexity, wind turbine design is mainly based on the cyclical design processes consisting of optimization, verification and modification, which not only depend highly on the designer's experience, but also modifies the optimum aerodynamic configuration of wind turbine blades.…”

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confidence: 99%

Large-scale wind turbine blade design and aerodynamic analysis

Wang

Zhong

et al. 2011

Chin. Sci. Bull.

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Incorporating controlled elitism and dynamic distance crowding strategies, a modified NSGA-II algorithm based on a fast and genetic non-dominated sorting algorithm is developed with the aim of obtaining a novel multi-objective optimization design algorithm for wind turbine blades. As an example, a high-performance 1.5 MW wind turbine blade, taking maximum annual energy production and minimum blade mass as the optimization objectives, was designed. A 1/16-scale model of this blade was tested in a 12 m × 16 m wind tunnel and the experimental results validated the high performance. Moreover, both the computational fluid dynamics (CFD) method and a free-vortex method (FVM) were applied to calculating the aerodynamic performance, which was consistent with the experimental data. For completeness, the CFD and FVM were used to analyze the wake structure, and good and consistent results were obtained between them.wind turbine, multi-objective optimization, wind tunnel test, CFD, free-vortex method Citation:Wang T G, Wang L, Zhong W, et al. Large-scale wind turbine blade design and aerodynamic analysis.

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“…͑3͒ iteratively between steps 2 and 3. The details of the iterative method can be found in Wang et al 16 In order to present the effect of flag shape, we introduce a new parameter, i.e., the nondimensional second moment of area r 2 , which was used in the research of the thrust capability of foil with different shapes. 17,18 It is defined as…”

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confidence: 99%

Flutter instability of rectangle and trapezoid flags in uniform flow

2010

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An experiment on the flutter instability of rectangle and trapezoid flags is conducted in a low speed wind tunnel and a physical model is proposed to predict the critical velocity of flutter instability of the flags. The nondimensional second moment of area is used to depict the effect of the flag shape on the flutter. The result shows that the method presented in this paper can be used to predict the lower-critical velocity. The change of the flutter envelope and critical velocity is found to be related to the dominant mode.Although the flutter instability of a flag immersed in uniform flow has been studied extensively, 1-3 it undoubtedly remains a hot subject of relevant research. [4][5][6][7][8][9] In most studies, the system was approximated as a one-dimensional flag with a finite length, and moreover, the flag was regarded as a cantilever beam, the motion of which obeyed the EulerBernoulli beam equation with additional pressure force coming from the flow. However, a real flag has a finite span or various shapes besides a finite length. To date, some researches have dealt with the instability of a two-dimensional flag. Eloy et al. 6,10 and Bao et al. 11 studied experimentally the effect of the span of rectangle flags on the flutter in a low speed wind tunnel. Eloy et al. 10 presented a method to predict the critical velocity of the flutter instability of a finite span rectangle plate. In their stability analysis, the flutter modes were assumed to be two-dimensional, but the threedimensional effect of the side-edges of the rectangle plate was also taken into consideration. An average pressure along the span of the plate was calculated and was regarded as the pressure acting on an infinite span plate. It was concluded that a plate of finite span is more stable than a plate of infinite span. Depending on the aspect ratio of the plate span H to the chord L, two asymptotic limits were obtained, i.e., the slender body approximation 12 for H Ӷ L and the large span approximation for H ӷ L. In the present paper, we study experimentally the critical instability velocity of the flutter of rectangle and trapezoid flags in uniform flow and compare the results with the predictions of a simplified model.As shown in Fig. 1͑a͒, the experiments were conducted in a low speed wind tunnel with a square test section of 1.0ϫ 1.0 m 2 . The flow velocity U in the test section was measured with a hot-wire anemometry ͑TSI-8384-M-GB͒, which ranges from 3 to 50 m/s. The flag models were cut from the sheets of polyethylene terephthalate. The thickness of the models h is 110 m, the mass per unit area m is 0.134 kg/ m 2 , and the unit span flexural rigidity D is 3.385 ϫ 10 −4 N m. In the experiments, a flag model was vertically fixed in the central region of the test section, with its leading edge clamped by two tensioned steal threads with a diameter of 0.1 mm. In such a way, the disturbance from the strut of the leading edge was reduced to a great extent. A light sheet emitted from a semiconductor laser of 1.5 W illuminated the flag and ...

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A numerical method to simulate the coupled oscillations of flexible structures in flowing fluids

Cited by 13 publications

References 31 publications

Bifurcation and chaos of a flag in an inviscid flow

Bifurcation and chaos of a flag in an inviscid flow

Large-scale wind turbine blade design and aerodynamic analysis

Flutter instability of rectangle and trapezoid flags in uniform flow

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