Development of Reduced-Order Models for Feedback Control of Axisymmetric Jets

2010 ◽  
Author(s):  
Aniruddha Sinha ◽  
Andrea Serrani ◽  
Mo Samimy
Keyword(s):  
Feedback Control ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Axisymmetric Jets

Feedback control of flow resonances using balanced reduced-order models

2011 ◽  
Vol 330 (8) ◽  
pp. 1567-1581 ◽  
Author(s):  
Simon J. Illingworth ◽  
Aimee S. Morgans ◽  
Clarence W. Rowley
Keyword(s):  
Feedback Control ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Control Of Flow

scholarly journals Feedback control of unstable steady states of flow past a flat plate using reduced-order estimators

2010 ◽  
Vol 645 ◽  
pp. 447-478 ◽  
Author(s):  
S. AHUJA ◽  
C. W. ROWLEY
Keyword(s):  
Steady State ◽  
Feedback Control ◽  
Flat Plate ◽  
Linear Systems ◽  
Vortex Shedding ◽  
Control Design ◽  
Balanced Truncation ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Unstable Steady State

We present an estimator-based control design procedure for flow control, using reduced-order models of the governing equations linearized about a possibly unstable steady state. The reduced-order models are obtained using an approximate balanced truncation method that retains the most controllable and observable modes of the system. The original method is valid only for stable linear systems, and in this paper, we present an extension to unstable linear systems. The dynamics on the unstable subspace are represented by projecting the original equations onto the global unstable eigenmodes, assumed to be small in number. A snapshot-based algorithm is developed, using approximate balanced truncation, for obtaining a reduced-order model of the dynamics on the stable subspace.The proposed algorithm is used to study feedback control of two-dimensional flow over a flat plate at a low Reynolds number and at large angles of attack, where the natural flow is vortex shedding, though there also exists an unstable steady state. For control design, we derive reduced-order models valid in the neighbourhood of this unstable steady state. The actuation is modelled as a localized body force near the trailing edge of the flat plate, and the sensors are two velocity measurements in the near wake of the plate. A reduced-order Kalman filter is developed based on these models and is shown to accurately reconstruct the flow field from the sensor measurements, and the resulting estimator-based control is shown to stabilize the unstable steady state. For small perturbations of the steady state, the model accurately predicts the response of the full simulation. Furthermore, the resulting controller is even able to suppress the stable periodic vortex shedding, where the nonlinear effects are strong, thus implying a large domain of attraction of the stabilized steady state.

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