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Keywords = unsteady aerodynamics in the Laplace domain

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23 pages, 1041 KB  
Article
Active Flutter Suppression of a Wing Section in the Subsonic, Sonic and Supersonic Regimes by the H Control Method
by Álvaro Muñoz and Pablo García-Fogeda
Aerospace 2024, 11(3), 198; https://doi.org/10.3390/aerospace11030198 - 29 Feb 2024
Cited by 3 | Viewed by 2138
Abstract
This paper compares various procedures for determining the optimal control law for a wing section in compressible flow. The flow regime includes subsonic, sonic and supersonic flows. For the evolution of the system in the Laplace plane, the present method makes use of [...] Read more.
This paper compares various procedures for determining the optimal control law for a wing section in compressible flow. The flow regime includes subsonic, sonic and supersonic flows. For the evolution of the system in the Laplace plane, the present method makes use of the exact unsteady aerodynamic forces in this plane once the control law is established. This is a great advantage over other results previously published, where the unsteady aerodynamics in the Laplace plane are merely approximations of the curve-fitted values in the frequency domain (imaginary axis). A comparison of different control techniques like pole placement, LQR and H-infinity control demonstrates that the H-infinity controller is the optimal choice, exhibiting an H-infinity norm approximately two orders of magnitude lower than the LQR case. Furthermore, the H-infinity controller demonstrates lower pole values than those of the pole placement and LQR compensator, showing the advantage of the H-infinity controller in terms of economic efficiency. Full article
(This article belongs to the Special Issue Active Flutter Suppression and Gust Load Alleviation)
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20 pages, 670 KB  
Article
Active Flutter Suppression of a Wing Section in a Compressible Flow
by Álvaro Muñoz and Pablo García-Fogeda
Aerospace 2022, 9(12), 804; https://doi.org/10.3390/aerospace9120804 - 7 Dec 2022
Cited by 4 | Viewed by 2124
Abstract
In this paper, a unified method for the computation of the unsteady aerodynamic forces in the Laplace domain for a wing section in subsonic, sonic and supersonic potential flows is presented. The subsonic solution is a new development based on the pressure mode [...] Read more.
In this paper, a unified method for the computation of the unsteady aerodynamic forces in the Laplace domain for a wing section in subsonic, sonic and supersonic potential flows is presented. The subsonic solution is a new development based on the pressure mode method. The unsteady aerodynamic forces are evaluated in the Laplace domain by an efficient method for computing the kernel. The sonic potential flow solution is an extension of the solution for the frequency domain to the Laplace domain. Analytical expressions for the unsteady pressure coefficient and the unsteady aerodynamic forces in the Laplace domain are obtained for this flow regime. The method is validated in these regimes with existing theories in the frequency domain, and its application to flutter computation is provided for different Mach numbers by the use of the p-method. Active flutter suppression for a wing section with three degrees of freedom has been studied, and an adequate control law has been obtained. Using the proposed approach allows to calculate the unsteady aerodynamic forces directly in the Laplace domain, avoiding the inconvenience of the curve fitting from the frequency to the Laplace domain. In particular, this work can be used as a base for the application of other procedures for flutter suppression in the transonic regime. Full article
(This article belongs to the Special Issue Structural Dynamics and Control)
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