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Réduction de modèle et contrôle en boucle fermée d'écoulements de type oscillateur et amplificateur de bruit

Abstract : This work deals with the closed-loop control of disturbances which develop linearly in laminar and incompressible flows. The control of both oscillator and amplifier flows is assessed. We consider a LQG control strategy in which the control law is computed using a reduced-order model of the flow. This reduced-order model is obtained by a Petrov-Galerkin projection. The first part is devoted to the stabilization of an open cavity flow which behaves as an oscillator. It is shown that the unstable subspace of the flow (the unstable global modes) and the input-output behaviour between the actuator and the sensor of the stable subspace must be captured by the reduced-order model to stabilize the system. Global modes, POD modes and BPOD modes are successively evaluated as projection bases to construct a reduced-order model of the stable part of the flow. It appears that global modes are not able to reproduce the input-output behaviour of the stable part of the flow and subsequently may only stabilize the flow if the instability is very weak (close to the criticality). On the contrary, reduced-order models based on POD modes and BPOD modes efficiently extract the input-output dynamic of the stable subspace and are successful to stabilize the flow. The second part of this work is dedicated to the reduction of the disturbances' amplification on a backward facing step. The influence of the sensor's location and of the cost functional on the performance of the compensator is studied. It is shown that the truncation of the reduced-order model may lead to an unstable closed-loop system. Finally, the possibility to control a non-linear simulation using a linear compensator is evaluated.
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https://pastel.archives-ouvertes.fr/pastel-00654930
Contributor : Alexandre Barbagallo <>
Submitted on : Friday, December 23, 2011 - 6:20:46 PM
Last modification on : Friday, October 23, 2020 - 4:38:04 PM
Long-term archiving on: : Saturday, March 24, 2012 - 2:25:26 AM

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  • HAL Id : pastel-00654930, version 1

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Alexandre Barbagallo. Réduction de modèle et contrôle en boucle fermée d'écoulements de type oscillateur et amplificateur de bruit. Mécanique des fluides [physics.class-ph]. Ecole Polytechnique X, 2011. Français. ⟨pastel-00654930⟩

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