Unsteady aerodynamic modeling for arbitrary motions

Edwards, John W.; Ashley, Holt; Breakwell, J. V.

doi:10.2514/6.1977-451

Cited by 45 publications

(17 citation statements)

References 9 publications

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“…As shown by Edwards et al [12] for linear systems, the aeroelastic governing equations of lifting surfaces can be converted from the time domain to the frequency domain via a Laplace transform. In the case of zero initial conditions, using the correspondence s → ik, the time-domain representation of the aerodynamic loads passes into the frequencydomain representation.…”

Section: Formulation Of the Aeroelastic Problemmentioning

confidence: 99%

“…3. Herein, comparisons with the CFD Euler code, indicial function, and the ones based on the approaches presented in references [3] and [12] are presented. Although the predictions agree well with the ones based on the indicial functions by Bisplinghoff et al [3] in the subsonic flight speed range (i.e.…”

Section: Subsonic Compressible Flight Speed Regimementioning

confidence: 99%

“…For the condition stated in reference [12], the conversion of equations (15) to the frequency domain is obtained by replacing s with ik. Keeping in mind the relationship between Theodorsen's function C k and Wagner's function ik , one can define for the compressible flight speed regime an analogous of Theodorsen's function expressed in terms of the corresponding indicial functions as…”

Section: Subsonic Compressible Flight Speed Regimementioning

confidence: 99%

See 2 more Smart Citations

Development of an indicial function approach for the two-dimensional incompressible/compressible aerodynamic load modelling

Marzocca

Librescu

Kim

et al. 2007

Proceedings of the Institution of Mechanical Engineers, Part G:

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By using a combined analytical-computational methodology, a unified modelling of aerodynamic indicial functions covering the incompressible, subsonic compressible, transonic, and supersonic flight speed regimes is presented. The procedure is carried out in conjunction with a computational fluid dynamic analysis. For a plunging-pitching airfoil, selected unsteady aerodynamic load expressions have been supplied, and appropriate procedures enabling one to obtain these loads via the indicial function approach have been presented. While a single indicial function is needed to describe the aerodynamic loads in the incompressible flight speed regime, for cases where the compressibility effects play a dominant role, four indicial functions are needed. Having in view the usefulness of indicial functions towards determination of unsteady aerodynamics loads in both time and frequency domains, and implicitly for aeroelastic response and flutter predictions, the advantages of their implementation and use appear evident. Comparisons and validations of the aerodynamic model against numerical, analytical, and experimental results are presented, and pertinent conclusions are drawn.Keywords: linear/non-linear indicial aerodynamic functions, incompressible and compressible flight speed regimes, two-degrees-of-freedom airfoil aerodynamics JAERO88

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Section: Formulation Of the Aeroelastic Problemmentioning

confidence: 99%

Section: Subsonic Compressible Flight Speed Regimementioning

confidence: 99%

Section: Subsonic Compressible Flight Speed Regimementioning

confidence: 99%

See 1 more Smart Citation

Development of an indicial function approach for the two-dimensional incompressible/compressible aerodynamic load modelling

Marzocca

Librescu

Kim

et al. 2007

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…[5] and further developed in Refs. The theoretical model considered here is a three-degree-of-freedom airfoil section with a nonlinear structural freeplay in flap rotation.…”

Section: Introductionmentioning

confidence: 99%

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

Kholodar¹,

Dowell²

2000

International Journal of Nonlinear Sciences and Numerical Simulation

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The influence of a "frozen" harmonic gust excitation on an aeroelastic nonlinear system with a control surface freeplay at nonzero angles of attack is examined in the context of a three-degree-of-freedom airfoil. The formulation of the numerical model is based on Theodorsen's aerodynamics and is extended to account for nonlinear arbitrary motion and gust loads. By time marching of the governing equations, the system response is determined and the complex nonlinear behavior is observed. Results indicate that there is no suppressing effect due to a nonzero mean angle of attack for such a system under gust loads. A companion experimental test program in a wind tunnel with a gust generator is used to validate the numerical results. The good agreement between theory and experiment demonstrates the efficiency and accuracy of the computational method.

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“…Active contol of aeroelastic systems in state space setting has been the subject of several research articles in recent years (see, e.g., [2], [3], [6], and [9]). The mathematical models considered in these studies can be described as systems of singular integrodifferential equations of Volterra [2] or neutral type [6].…”

Section: Introductionmentioning

confidence: 99%

On input/output stabilization of singular integrodifferential systems

Özbay

Turi

1994

Appl Math Optim

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Abstract. In this paper we consider a class of systems described by singular integrodifferential equations. This type of systems appear, for example, in the modeling of certain aeroelastic control problems. We study these systems in frequency domain framework and show the existence of finite-dimensional stabilizing controllers. An algorithmic procedure is outlined for the construction of such controllers. In order to illustrate the numerical aspects of this algorithm, we present an example involving the classical Theodorsen model of an airfoil, which fits in the class of systems considered here.

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Unsteady aerodynamic modeling for arbitrary motions

Cited by 45 publications

References 9 publications

Development of an indicial function approach for the two-dimensional incompressible/compressible aerodynamic load modelling

Development of an indicial function approach for the two-dimensional incompressible/compressible aerodynamic load modelling

The Influence of a Nonzero Angle of Attack and Gust Loads on the Nonlinear Response of a Typical Airfoil Section with a Control Surface Freeplay

On input/output stabilization of singular integrodifferential systems

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