Quasi-steady prediction of coupled bending–torsion flutter under rotating stall
TL;DR: In this paper, a method is presented to predict cascade flutter under subsonic stalled flow condition in a quasi-steady manner, where the linearized aerodynamic theory of Whitehead is used to estimate the blade loading.
About: This article is published in Journal of Fluids and Structures.The article was published on 2013-11-01. It has received 6 citations till now. The article focuses on the topics: Flutter.
Citations
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01 Jan 2017
TL;DR: In this article, a method for determining the aeroelastic stability boundaries of a cascade with aerodynamic, inertial, and structural coupling between the bending and torsional degrees of freedom is presented.
Abstract: A method is presented for determining the aeroelastic stability boundaries of a cascade with aerodynamic, inertial, and structural coupling between the bending and torsional degrees of freedom. A computer program has been written to systematically investigate the effect of this coupling on cascade stability over a wide range of design parameters. Results presented illustrate that the bending-torsion interaction has a pronounced effect on the cascade flutter boundary, despite no appreciable tendency toward frequency coalescence as flutter is approached. The analysis also indicates that bending flutter is possible even in the absence of finite mean lift.
52 citations
TL;DR: In this article, the authors investigated the variations in airloads and blade behavior of a wind turbine blade resulting from operations in sheared and turbulent flow conditions, and compared the results among the blade element momentum method, free-wake method, and numerical results from previous studies.
22 citations
TL;DR: In this article, a 2-DOF blade section is considered, with a simplified stall nonlinear aerodynamic model being applied to solve the problem of stall flutter suppression for an absolutely divergent blade of small scale wind turbine.
Abstract: This paper is devoted to solve the problem of stall flutter suppression for an absolutely divergent blade of small scale wind turbine. The blade is specially designed with absolutely divergent motions for the purpose of determining the most effective methods of active control for stall flutter suppression. A 2-DOF blade section is considered, with a simplified stall nonlinear aerodynamic model being applied. H-infinity mixed-sensitivity synthesis method with a new three-weight regulation is designed to control the time-domain instability of aeroelastic equations, with a third weight being chosen to weight complementary sensitivity for tracking problems and noise attenuation to robust stabilization in H- infinity control. Effects on flutter suppression are investigated based on different structural and external parameters. Apparent effects of H-infinity mixed-sensitivity method are displayed in the paper, when the other common intelligent control methods fail. The research provides a control way for absolutely divergent turbine blade motions. As typical nonlinear aeroelastic instable vibration, stall flutter is an important reason of fatigue damage for wind turbine. How to effectively avoid flutter instability has become an important subject needed to be investigated. Meanwhile in this area, the investigation of typical blade section based on the simplified stall flutter of 2-DOF flap/lag motions plays an important role due to its simplicity and high efficiency (1). Hence in this study, stall flutter suppression will be depicted based on 2-DOF blade section. In recent years, a number of issues related to the modeling, vibration analysis, and control methods for stall flutter are investigated. Shantanu experimentally studies and demarcates the stall flutter boundaries of an airfoil by measuring the forces and flow fields around the airfoil when it is forced to oscillate (2). S. Sarkar investigates the effect of system parametric uncertainty on the stall flutter bifurcation behavior of a pitching airfoil, with the aerodynamic moment on the two-dimensional rigid airfoil being computed using the ONERA dynamic stall model (3). J. Peiro investigates the dynamics of a typical airfoil section and demonstrates the importance of the added mass terms, with structural behavior being modeled by linear springs and the aerodynamic loading being exerted by Beddoes-Leishman (B-L) model (4). Zhiwei adopts a nonlinear time-domain aeroservoelastic model and designs flutter suppression control systems, with a novel state-space model being descripted for control design (5). Ananth presents a method to predict cascade flutter under subsonic stalled flow condition in a quasi-steady
3 citations
Additional excerpts
...1874-155X/15 2015 Bentham Open Keywords: Flutter suppression, H-infinity mixed-sensitivity synthesis method, stall flutter, three-weight regulation....
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2 citations
TL;DR: In this paper, the authors report the results of the fluid-structure interaction study of a lightly cambered blade in a cascade under the influence of various inflow conditions and structural parameters.
2 citations
References
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02 May 1934
TL;DR: In this paper, the Kutta condition was used to analyze the aerodynamic forces on an oscillating airfoil or an air-foil-aileron combination of three independent degrees of freedom.
Abstract: The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom were determined. The problem resolves itself into the solution of certain definite integrals, which were identified as Bessel functions of the first and second kind, and of zero and first order. The theory, based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing section theory relating to the steady case. The air forces being known, the mechanism of aerodynamic instability was analyzed. An exact solution, involving potential flow and the adoption of the Kutta condition, was derived. The solution is of a simple form and is expressed by means of an auxiliary parameter k. The flutter velocity, treated as the unknown quantity, was determined as a function of a certain ratio of the frequencies in the separate degrees of freedom for any magnitudes and combinations of the airfoil-aileron parameters.
2,153 citations
TL;DR: In this paper, an approximate theory for post-stall transients in multistage axial compression systems is presented, which leads to a set of three simultaneous nonlinear third-order partial differential equations for pressure rise, and average and disturbed values of flow coefficient, as functions of time and angle around the compressor.
Abstract: An approximate theory is presented for post-stall transients in multistage axial compression systems. The theory leads to a set of three simultaneous nonlinear third-order partial differential equations for pressure rise, and average and disturbed values of flow coefficient, as functions of time and angle around the compressor. By a Galerkin procedure, angular dependence is averaged, and the equations become first order in time. These final equations are capable of describing the growth and possible decay of a rotating-stall cell during a compressor mass-flow transient. It is shown how rotating-stall-like and surgelike motions are coupled through these equations, and also how the instantaneous compressor pumping characteristic changes during the transient stall process.
812 citations
Book•
31 Aug 1989TL;DR: Aeroelasticity in Turbomachines has been studied in this article for complex and nonlinear unsteady flows in turbomachines, where the model of fluid-structure interaction has been used.
Abstract: Static Aeroelasticity.- Dynamic Aeroelasticity.- Nonsteady Aerodynamics of Lifting and Non-Lifting Surfaces.- Stall Flutter.- Aeroelasticity in Civil Engineering.- Aeroelastic Response of Rotorcraft.- Aeroelasticity in Turbomachines.- Modeling of Fluid-Structure Interaction.- Experimental Aeroelasticity.- Nonlinear Aeroelasticity.- Aeroelastic Control.- Modern Analysis for Complex and Nonlinear Unsteady Flows in Turbomachinery.
636 citations
01 Jan 1935
TL;DR: In this paper, the Kutta condition was used to analyze the aerodynamic forces on an oscillating airfoil or an air-foil-aileron combination of three independent degrees of freedom.
Abstract: The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom were determined. The problem resolves itself into the solution of certain definite integrals, which were identified as Bessel functions of the first and second kind, and of zero and first order. The theory, based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing section theory relating to the steady case. The air forces being known, the mechanism of aerodynamic instability was analyzed. An exact solution, involving potential flow and the adoption of the Kutta condition, was derived. The solution is of a simple form and is expressed by means of an auxiliary parameter k. The flutter velocity, treated as the unknown quantity, was determined as a function of a certain ratio of the frequencies in the separate degrees of freedom for any magnitudes and combinations of the airfoil-aileron parameters.
351 citations
TL;DR: In this paper, a limited parametric study is carried out to illustrate the impact of different system features on transient behavior, and it is shown that the ultimate mode of system response, surge or stable rotating stall, depends not only on the B parameter, but also on the compressor length-to-radius ratio.
Abstract: Using the theory developed in Part I, calculations have been carried out to show the evolution of the mass flow, pressure rise, and rotating-stall cell amplitude during compression system post-stall transients. In particular, it is shown that the unsteady growth or decay of the stall cell can have a significant effect on the instantaneous compressor pumping characteristic and hence on the overall system behavior. A limited parametric study is carried out to illustrate the impact of different system features on transient behavior. It is shown, for example, that the ultimate mode of system response, surge or stable rotating stall, depends not only on the B parameter, but also on the compressor length-to-radius ratio. Small values of this latter quantity tend to favor the occurrence of surge, as do large values of B. Based on the analytical and numerical results, several specific topics are suggested for future research on post-stall transients.
344 citations