Nonlinear aeroelastic behavior of an oscillating airfoil during stall-induced vibration
TL;DR: In this paper, a parametric study on the aeroelastic instability and the nonlinear dynamical behavior of a two-dimensional symmetric rotor blade in the dynamic stall regime is investigated.
About: This article is published in Journal of Fluids and Structures.The article was published on 2008-08-01. It has received 61 citations till now. The article focuses on the topics: Aeroelasticity & Oscillation.
Citations
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TL;DR: In this article, the dynamical response of a two-degree-of-freedom flat plate undergoing classical coupled-mode flutter in a wind tunnel is explored using an aeroelastic set-up that enables high amplitude pitch-plunge motion.
96 citations
Cites background from "Nonlinear aeroelastic behavior of a..."
...…and Philippe, 1975; Carr et al, 1977) and to the aeroealastic response of a pure pitch or pitch-plunge airfoil in the post critical stall flutter condition (see for example Dunn and Dugundji, 1992; Price & Fragiskatos, 2000; Li and Dimitriadis, 2007; Sarkar and Bijl, 2008; Razak et al, 2011)....
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TL;DR: In this paper, three models are used to simulate the Ohio State University measurements and a set of data from the National Aeronautics and Space Administration Ames experimental study of dynamic stall and compare results.
Abstract: The dynamic stall phenomenon and its importance for load calculations and aeroelastic simulations is well known. Different models exist to model the effect of dynamic stall; however, a systematic comparison is still lacking. To investigate if one is performing better than another, three models are used to simulate the Ohio State University measurements and a set of data from the National Aeronautics and Space Administration Ames experimental study of dynamic stall and compare results. These measurements were at conditions and for aerofoils that are typical for wind turbines, and the results are publicly available. The three selected dynamic stall models are the ONERA model, the Beddoes–Leishman model and the Snel model. The simulations show that there are still significant differences between measurements and models and that none of the models is significantly better in all cases than the other models. Especially in the deep stall regime, the accuracy of each of the dynamic stall models is limited. Copyright © 2012 John Wiley & Sons, Ltd.
64 citations
DOI•
14 Nov 2012
TL;DR: In this paper, the authors investigated the technical and economical feasibility and limits of large scale offshore wind turbines using the current dominant concept, i.e., a three-bladed, upwind, variable speed, pitch regulated wind turbine installed on a monopile in an offshore wind farm.
Abstract: Issues related to environmental concern and fossil fuel exhaustion has made wind energy the most widely accepted renewable energy resource. However, there are still several challenges to be solved such as the integrated design of wind turbines, aeroelastic response and stability prediction, grid integration, offshore resource assessment and scaling related problems. While analyzing the market of wind turbines to find the direction of the future developments, one can see a continuous upscaling of wind turbines. Upscaling is performed to harness a larger resource and benefit from economy of scale. This will pose several fundamental implications that have to be identified and tackled in advance. This research focuses on investigating the technical and economical feasibility and limits of large scale offshore wind turbines using the current dominant concept, i.e. a three-bladed, upwind, variable speed, pitch regulated wind turbine installed on a monopile in an offshore wind farm. Thus, the objective of this research is to investigate how upscaling influences the offshore wind turbines. Specifically, following questions are of interest: 1. How do the technical characteristics of the larger scales change with size and can these technical characteristics appear as a barrier? 2. How does the economy of the future offshore wind turbines change with size? 3. What are the considerations and required changes for future offshore wind turbines? To address these questions, a more sophisticated method than the classical upscaling method should be employed. This method should provide the detailed technical and economical data at larger scales and address all the design drivers of such big machines to identify the associated problems. However, interdisciplinary interactions among structure, aerodynamics and control subject to constraints on fatigue, stresses, deflections and frequencies as well as considerations on aeroelastic instability make the development of such a method a cumbersome and complex task. Among many different methods, integrated aeroservoelastic design optimization is found to be the best approach. Therefore, the scaling study of this research is formulated as an multidisciplinary design optimization problem. This method enables the design of the future offshore wind turbines at the required level of details that is needed to investigate the effect of size on technical and economical characteristics at larger scales. Using this method, 5, 10 and 20 MW wind turbines are designed and optimized, including the most relevant design constraints and levelized cost of energy as the objective function. In addition to the design of these wind turbines, the method itself shows a clear way forward for the future offshore wind turbine design methodology development. Based on these optimized wind turbines, scaling trends are constructed to investigate the behavior of a wind turbine as it scales with size. These trends are formulated as a function of rotor diameter to properly reflect the scale. Loading, mass, cost and some other useful trends are extracted to investigate the scaling phenomenon. Blades and tower as the most flexible load carrying components are examined with more attention. Using these results, the challenges of very large scale offshore wind turbines up to 20 MW range are explored and identified. These results demonstrate that a 20 MW design is technically feasible though economically not attractive. Therefore, upscaling of the current wind turbine configurations seems to be an inappropriate approach for larger offshore wind turbines.
55 citations
TL;DR: In this article, high-frequency limit-cycle oscillations of an airfoil at low Reynolds number were studied numerically, where the aerodynamic model used in the aeroelastic framework is a potential-flow-based discrete-vortex method, augmented with intermittent leading-edge vortex shedding based on a leading edge suction parameter reaching a critical value.
44 citations
TL;DR: In this article, the aeroelastic response of a NACA 0012 airfoil in the flow regimes prior to flutter is investigated in a wind tunnel, where the authors observe intermittent bursts of periodic oscillations in the pitch and plunge response, that appear in an irregular manner from a background of relatively lower amplitude aperiodic fluctuations.
44 citations
Cites background or methods from "Nonlinear aeroelastic behavior of a..."
...Zimmerman and Weissenburger (1964) proposed a methodology to derive a flutter margin based on Routh's stability criterion (Fung, 1955), which was applied to a two degree of freedom system under the assumption of quasi-steady aerodynamics....
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...Stability characteristics and bifurcation behavior of aeroelastic systems having both structural and aerodynamic nonlinearities have been extensively investigated in the literature (Alighanbari and Price, 1996; Lee et al., 1999; Dowell and Tang, 2002; Sarkar and Bijl, 2008)....
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References
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TL;DR: In this article, the authors present the first algorithms that allow the estimation of non-negative Lyapunov exponents from an experimental time series, which provide a qualitative and quantitative characterization of dynamical behavior.
8,128 citations
Book•
01 Jan 1955
TL;DR: An introduction to the theory of aeroelasticity, An Introduction to the Theory of Aero-Elasticity as mentioned in this paper, An introduction to aero-elasticities,
Abstract: An introduction to the theory of aeroelasticity , An introduction to the theory of aeroelasticity , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
1,352 citations
775 citations
TL;DR: In this article, the equations of motion of a two-dimensional airfoil oscillating in pitch and plunge are derived for a structural nonlinearity using subsonic aerodynamics theory.
421 citations
TL;DR: In this article, a nonlinear, stalled, aeroelastic behavior of rectangular, graphite/epoxy, cantilevered wings with varying amount of bending-torsi on stiffness coupling is investigated.
Abstract: The nonlinear, stalled, aeroelastic behavior of rectangular, graphite/epoxy, cantilevered wings with varying amount of bending-torsi on stiffness coupling is investigated. A nonlinear aeroelastic analysis is developed using the nonlinear, stalled ONERA aerodynamic model initially presented by Tran and Petot. Nonlinear flutter calculations are carried out using Fourier analysis to extract the harmonics from the ONERA aerodynamics, then a harmonic balance method and a Newton-Raphson solver are applied to the resulting nonlinear, Rayleigh-Ritz aeroelastic formulation. Test wings were constructed and subjected to wind-tunnel tests for comparison against the developed analysis. Wind-tunnel tests show reasonable agreement between theory and experiment for static deflections, for linear flutter and divergence, and for nonlinear, torsional stall flutter and bending stall flutter limit cycles. The current nonlinear analysis shows a transition from divergence to bending stall flutter, which linear analyses are unable to predict.
108 citations