OATAO - Open Archive Toulouse Archive Ouverte Open Access Week

Analysis and control of self-sustained instabilities in a cavity using reduced order modelling

Nagarajan, Kaushik Kumar. Analysis and control of self-sustained instabilities in a cavity using reduced order modelling. PhD, Institut National Polytechnique de Toulouse, 2010

[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
2MB
[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
8MB
[img]
Preview
(Document in English)

PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
1MB

Official URL: http://ethesis.inp-toulouse.fr/archive/00001104/

Abstract

We consider a two dimensional compressible flow around an open cavity. The Flow around a cavity is characterised by a self-sustained mechanism in which the shear layer impinges on the downstream edge of the cavity resulting in an acoustic feedback mechanism which must be reduced. Direct Numerical Simulations (DNS) of the flow at a representative Reynolds number has been carried to obtain pressure and velocity fields, both for the case of unactuated and multi frequency actuation. These fields are then used to extract energy ranked coherent structures also called as the Proper Orthogonal Decomposition (POD) modes. A Reduced Order Model is constructed by a Galerkin projections of the isentropic compressible equations. The model is then extended to include the effect of control. To avoid the divergence of the model while integrating in time various calibration techniques has been utillized. A new method of calibration which minimizes a linear functional of error, based on modal sensitivity is proposed. The calibrated low order model is used to design a feedback control of the Linear Quadratic Gaussian (LQG) type, coupled with an observer. For the experimental implementation of the controller, a state estimate based on the observed pressure measurements at 6 different locations, is obtained through a Linear Stochastic Estimation (LSE). The optimal control obtained is periodic with a frequency corresponding to the second Rossiter mode of the cavity. Finally the control obtained is introduced into the DNS to obtain a decrease in spectra of the cavity acoustic mode.

Item Type:PhD Thesis
Uncontrolled Keywords:
Institution: Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Laboratory name:
Research Director:
Airiau, Christophe and Kourta, Azeddine
Statistics:download
Deposited By: admin admin

Repository Staff Only: item control page