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/gt2014-25648

Cited by 8 publications

(4 citation statements)

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“…The angle of attack is 40 • and the Reynolds number is 100,000 (U = 5.8 m/s). Figure 9d and other comparable data may be found in Besem et al [51]. The diamond symbols represent conditions where the shedding and enforced frequencies are unlocked, the circle symbols show lockin conditions, and the square symbols have a chaotic behavior that can be attributed to the edge of the lock-in region.…”

Section: Correlation Analyses For Frequency Lock-in Regionsupporting

confidence: 82%

Experimental Aeroelastic Models Design and Wind Tunnel Testing for Correlation with New Theory

Tang

Dowell

2016

Aerospace

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Section: Correlation Analyses For Frequency Lock-in Regionsupporting

confidence: 82%

Experimental Aeroelastic Models Design and Wind Tunnel Testing for Correlation with New Theory

Tang

Dowell

2016

Aerospace

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“…These conclusions came from utilizing POD methods to create a ROM, which can predict results faster and as accurate as full computational models, requiring at least two degrees of freedom and two harmonics. In addition, Besem and Tang performed experimental studies on the lock-in region for a NACA 0012 airfoil [92]. They found that the lock-in region to experiments is wider, capturing the chaotic edge region between locked and unlocked.…”

Section: Aerodynamic Lco: Buffet Aws and Nsvmentioning

confidence: 99%

Some Recent Advances in Nonlinear Aeroelasticity

Dowell

2021

A Modern Course in Aeroelasticity

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This brings the discussion of nonlinear aeroelasticity up to date. See the earlier discussion in Chap. 11. Much of the recent advances are based on new understanding of such subjects as limit cycle oscillations due to structural non-linearities, including freeplay, and fluid nonlinearities associated with unsteady separated flow including self excited flow oscillations variously called buffet or non-synchronous vibration.As the reader now knows, aeroelasticity is the field that examines, models and seeks to understand the interaction of the forces from an aerodynamic flow and the deformation of an elastic structure. The forces produce deformation, but the structural deformation in turn changes the aerodynamic forces. This feedback between force and deformation leads to a variety of dynamic responses of the fluid and the structure including flutter (a Hopf bifurcation), limit cycle oscillations and sometimes chaos. Selected recent advances in nonlinear aeroelasticity and fluid-structure interaction are reviewed to identify and model the fundamental elements that they share. Topics discussed include the following. following. 1 1 This chapter is based upo a AIAA SDM lecture given in 2010.

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“…22. The potential "lock-in" phenomenon is a feature of NSV, which can be referred to the related phenomena in vortex-induced vibrations [23][24][25] that occurred in the cross-flow of a bluff body or a streamlined body at a high angle of attack. In vortexinduced vibrations, when the vortex shedding frequency is close to the body oscillation frequency, it may "jump" to the oscillation frequency, and the vibration amplitude will significantly increase.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigations on non-synchronous vibration and frequency lock-in of low-pressure steam turbine last stage

Zhu

Lin³

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The flow phenomenon of rotating instability (RI) and its induced non-synchronous vibrations (NSV) in the last stage have gradually become a security problem that restricts the long-term flexible operations of modern large-scaled low-pressure steam turbines. Especially, if one structural mode of the last stage moving blade (LSMB) is excited, significant blade vibrations may potentially lead to high-cycle fatigue failure. A loosely coupled computational fluid dynamics reduced model with prescribed blade vibrations has been established to investigate NSV of the LSMB and the potential lock-in phenomenon under low-load conditions. Firstly, calculations with reduced multi-passage domain have been verified by comparing with the results of the full-annulus one, and an appropriate reduced domain is determined. Secondly, a set of calculations by controlling blade vibration parameters indicate that lock-in phenomenon between RI frequency and blade vibration frequency may occur when nodal diameters of cascade vibrations is coincident with the wave number of RI. Furthermore, dynamic modal decomposition technology has been employed to identify the unsteady pressure field around the blade surface and to reveal the interaction relationship between the flow modes of RI and vibration-induced pressure disturbance. Finally, the blade response evaluation based on harmonic analysis shows that in NSV, the global maximum dynamic response level of locked-in case is nearly 20 times than that of unlocked one.

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

Cited by 8 publications

References 0 publications

Experimental Aeroelastic Models Design and Wind Tunnel Testing for Correlation with New Theory

Experimental Aeroelastic Models Design and Wind Tunnel Testing for Correlation with New Theory

Some Recent Advances in Nonlinear Aeroelasticity

Numerical investigations on non-synchronous vibration and frequency lock-in of low-pressure steam turbine last stage

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