Self‐induced vibrations of a DU96‐W‐180 airfoil in stall

Skrzypiński, Witold Robert; Gaunaa, Mac; Sørensen, Niels N.; Zahle, Frederik; Heinz, Joachim Christian

doi:10.1002/we.1596

Cited by 15 publications

(4 citation statements)

References 27 publications

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“…Many studies have been realised in the past on stallinduced vibrations experienced by stall-regulated wind turbines in normal condition [2,3,4]. But recently, stall-induced vibrations occurring on parked positions are under focus [5,6,7].…”

Section: Introductionmentioning

confidence: 99%

Numerical prediction of aerodynamic loads acting on a blade section-model oscillating in stall

Cortes,

Amandolese,

Pfister

et al. 2024

J. Phys.: Conf. Ser.

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For blades operating close to stall angle of attack, one of the potential instabilities is known as stall flutter. It is a dynamic instability in torsion for which the mechanism of energy transfer relies on a dynamic stall process where the flow separates partially or completely during each cycle of oscillation. It leads to dynamic loops in lift, drag and moment that affect the aerodynamic performance of the blade, create unsteady stresses in the blades and can lead to fatigue damage. In the present study, dynamic loops of a NACA 634421 airfoil in forced pitch oscillations have been simulated with the FastS CFD solver based on a URANS modelling approach and compared to benchmark experiments as well as results obtained with the ONERA semi-empirical dynamic stall model using a unique set of dynamic parameters that best fit the experimental dynamic loops. The dynamic tests have been conducted for a mean angle of attack of 13.5°, an amplitude of oscillation of 8° and three reduced frequencies k 1 = 0.0183, k 2 = 0.0785 and k 3 = 0.183. This study has shown that the CFD FastS solver can satisfactorily reproduce the unsteady lift and moment coefficients experienced by a section model oscillating in stall.

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Section: Introductionmentioning

confidence: 99%

Numerical prediction of aerodynamic loads acting on a blade section-model oscillating in stall

Cortes,

Amandolese,

Pfister

et al. 2024

J. Phys.: Conf. Ser.

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“…Among the issues raised by the increase in size of these new generation wind turbines is the aeroelastic behaviour, which poses challenges both in terms of modelling and design. Earlier studies [2,3,4,5,6,7] have reported and analysed the occurrence of stall-induced vibrations of wind turbine blades in idling conditions subject to a misaligned wind. These vibrations arise when the loss of lift and/or the unsteady loads resulting from the aerodynamic stall (caused by the misalignment of the blades with respect to the incoming wind) interact unfavourably with the mechanical structure of the blades [7], leading eventually to large-amplitude vibrations.…”

Section: Introductionmentioning

confidence: 99%

Stall flutter instabilities on the IEA-15 reference wind turbine in idling conditions: code-to-code comparisons and physical analyses

Loubeyres

Pfister

Blondel

et al. 2022

J. Phys.: Conf. Ser.

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The present study investigates stall-induced vibrations on a IEA-15-RWT wind turbine blade. At standstill and under specific strong crosswind conditions, simulations using the codes OpenFAST and DeepLines WindTM exhibit large-amplitude vibrations. Results of both codes are first compared, showing an overall good agreement. Then, the influence of the wind misalignment angle is assessed as well as the choice of aerodynamic polar datasets. Vibrations are observed within two well-marked angular sectors, and the high sensitivity of the phenomenon to the choice of polars is highlighted. Finally, a simplified model based on a spring-mounted aeroelastic section is used to help identifying which type of unstable aeroelastic modes may be at play.

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“…Skrzypiński et al (2014a) investigated stall-induced vibrations using 2-D RANS and 3-D DES aerodynamic simulations for a typical elastically mounted blade section in combined flap-edge motion. The 3-D simulations considered an extruded section and periodic spanwise flow conditions.…”

Section: Introductionmentioning

confidence: 99%

Aeroelastic stability of idling wind turbines

Wang¹,

Riziotis

Voutsinas

2017

Wind Energ. Sci.

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Abstract. Wind turbine rotors in idling operation mode can experience high angles of attack within the poststall region that are capable of triggering stall-induced vibrations. The aim of the present paper is to extend the existing knowledge on the dynamics and aerodynamics of an idling wind turbine and characterize its stability. Rotor stability in slow idling operation is assessed on the basis of nonlinear time domain and linear eigenvalue analyses. The aim is to establish when linear analysis is reliable and identify cases for which nonlinear effects are significant. Analysis is performed for a 10 MW conceptual wind turbine designed by DTU. First, the flow conditions that are likely to favor stall-induced instabilities are identified through nonlinear time domain aeroelastic simulations. Next, for the above specified conditions, eigenvalue stability analysis is performed to identify the low damped modes of the turbine. The eigenvalue stability results are evaluated through computations of the work done by the aerodynamic forces under imposed harmonic motion following the shape and frequency of the various modes. Nonlinear work characteristics predicted by the ONERA and Beddoes-Leishman (BL) dynamic stall models are compared. Both the eigenvalue and work analyses indicate that the asymmetric and symmetric out-of-plane modes have the lowest damping. The results of the eigenvalue analysis agree well with those of the nonlinear work analysis and the time domain simulations.

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Self‐induced vibrations of a DU96‐W‐180 airfoil in stall

Cited by 15 publications

References 27 publications

Numerical prediction of aerodynamic loads acting on a blade section-model oscillating in stall

Numerical prediction of aerodynamic loads acting on a blade section-model oscillating in stall

Stall flutter instabilities on the IEA-15 reference wind turbine in idling conditions: code-to-code comparisons and physical analyses

Aeroelastic stability of idling wind turbines

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