Vortex-Induced Vibration and Frequency Lock-In of an Airfoil at High Angles of Attack

Besem, Fanny M.; Kamrass, Joshua D.; Thomas, Jeffrey P.; Tang, Deman; Kielb, Robert E.

doi:10.1115/1.4031134

Cited by 43 publications

(13 citation statements)

References 21 publications

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“…The lock-in behavior of the airfoil oscillating with a prescribed pitching motion about the quarter-chord was determined ("V"-shaped lock-in region). Vortex-induced vibrations on the same airfoil in pitching motion at the same Reynolds number regime have been studied by Besem et al [21], both experimentally and numerically. Wind tunnel experiments were conducted for incidences α = 25°→ 90°.…”

Section: Background To Vortex Shedding and Wake Oscillatormentioning

confidence: 99%

Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack

Meskell

Pellegrino

2019

International Journal of Aerospace Engineering

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The unsteady flow around a pitching two-dimensional airfoil section (NREL S809) has been simulated using unsteady RANS with the transition SST turbulence model. This geometry is chosen to represent a wind turbine blade in a standstill configuration. The Reynolds number is Re = 10 6 based on a chord length of 1 m. A prescribed sinusoidal pitching motion has been applied at a fixed amplitude of 7°for a range of high angles of attack 30°< α < 150°. At these incidences, the airfoil will behave more like a bluff body and may experience periodic vortex shedding. It is well known that, in bluff body flows, oscillations can lead to a lock-in (lock-in) of the vortex shedding frequency, f v , with the body's motion frequency, f p . In order to investigate the susceptibility of airfoil to lock-in, the frequency ratio r (r = f p /f v0 ) has been varied around r = 1. The lock-in region boundaries have been proposed, and an analysis of the effect of the oscillation amplitude has been conducted. The lock-in map obtained suggests that, for the vibration amplitude considered, the risk of vortex-induced vibration is more significant in the regions of α ≈ 40°and α ≈ 140°, i.e., for shallower characteristic lengths. Finally, a lumped parameter wake oscillator model has been proposed for pitching airfoils. This simple model is in qualitative agreement with the CFD results.

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Section: Background To Vortex Shedding and Wake Oscillatormentioning

confidence: 99%

Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack

Meskell

Pellegrino

2019

International Journal of Aerospace Engineering

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“…Fluid-induced vibration which is a nonlinear and self-excited phenomenon occurs in many engineering applications such as aircraft wing and body [1][2][3], offshore oil and gas pipelines [4][5][6], marine structures [7], yacht and ship motors [8] and biomedical engineering [9,10]. In many of these cases, this type of vibrations can cause fatigue and failure of structures [11], e.g., fatigue caused by fl uid-induced has always been a threat to aircraft fl ight.…”

Section: Introductionmentioning

confidence: 99%

Vibration analysis of fluid-structure interaction using tuned mass dampers

Javanshir¹,

Zarepour²

2021

J Appl Eng Science

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This paper has investigated the semi-analytical analysis of the solid-fluid interaction vibration in the presence of concentrated mass-spring-damper vibration absorber. The nonlinear partial differential equations of motion are derived by considering von Karman-type large deformations and viscoelastic behaviour. Fluid-structure interaction is modelled by using an acceleration coupling model in which a nonlinear Van der Pol oscillator simulates fluctuating nature of the vortex street. The nonlinear equations are discretized via the Galerkin approach, and the obtained equations are numerically solved by applying the Runge–Kutta method. Eventually, the dynamic response, phase plane plots, and variations of maximum amplitude in terms of fluid velocity for different parameters are extracted. The results reveal that utilizing vibration absorber leads to a signifi cant effect on the dynamic characteristics of the system, displaces the lock-in phenomenon, and remarkably reduce the amplitude of the system oscillations.

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“…Three of the most common causes of nonlinearity are high angle of attack, transonic flow, and elastic structure [9][10][11][12]. Two-dimensional wind tunnel experiments were conducted to investigate the buffeting flow over a static airfoil and an oscillating pitching airfoil [13][14]. However, if the distance between the wind tunnel walls is not sufficiently wide relative to the characteristic length of the object being studied, the wall effects cannot be ignored, because they can greatly affect the object's aerodynamic characteristics.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Wind-Tunnel Wall Effects on Lift and Drag Characteristics of NACA 0012 Airfoil

Abobaker

Elfaghi

Addeep

2020

CFDL

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Possible interference effects of the wind tunnel walls play an important role especially for measurements in closed-wall test sections. In this study, a numerical analysis of two-dimensional subsonic flow over a NACA 0012 airfoil at different computational domain heights, angles of attack from 0o to 10o, and operating Reynolds number of 6×106 is presented. The work highlights the role of computational fluid dynamics (CFD) in the investigation of wind tunnel wall effect on lift curve slope correction factor (Ka). The flow solution is obtained using Ansys Fluent software by solving the steady-state continuity and momentum governing equations combined with turbulence model k-v shear stress transport (SST-K?). The numerical results are validated by comparing with the available experimental measurements. Calculations show that the lift curve slope correction results are very close to the published data.

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Vortex-Induced Vibration and Frequency Lock-In of an Airfoil at High Angles of Attack

Cited by 43 publications

References 21 publications

Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack

Vortex Shedding Lock-In due to Pitching Oscillation of a Wind Turbine Blade Section at High Angles of Attack

Vibration analysis of fluid-structure interaction using tuned mass dampers

Numerical Study of Wind-Tunnel Wall Effects on Lift and Drag Characteristics of NACA 0012 Airfoil

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