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Mathematical modelling and identiication of systems, where the structure of some equations is unknown, is a diicult task. As this is usually done manually by a human expert, it is associated with terms such as experience and intuition. However, an experienced modeller will have a clear procedure to deduce a model. In a rst step he or she will analyse(More)
Besides controller synthesis based on a high dimensional discretization or low dimensional description of the Navier-Stokes equation or based on black-box models identified in wind tunnel experiments, model-free methods such as extremum seeking control can be used advantageously to control fluid flows. This contribution gives a survey on several successful(More)
The ability to maintain a constant lift force on a low aspect ratio semi circular wing using pulsed blowing active flow control is experimentally investigated. Dynamic models of the wing's response to pressure (pulsed blowing) actuation and the response to longitudinal gusting are obtained through black-box system identification methods. Robust closed loop(More)
The ability to control lift in unsteady flows using active flow control is examined experimentally with a three-dimensional, low-aspect-ratio wing and pulsed-blowing actuators as the test article. An unsteady flow wind tunnel is used to generate step-like and harmonic oscillations in flow speed and the corresponding fluctuating lift force on the wing. A(More)
A new technique is presented to identify intervals for parameters and initial conditions for nonlinear dynamic systems based on an imprecise mathematical model and measurements of system variables. This technique employs a fuzz interval qualitative simulator for interval dynamical models and a qualitative description of measured signals , the episodes.(More)
Closed-loop control of separated flows is still hindered by a lack of fast and practical sensors for the measurement of the length of a separation bubble or of the position of reattachment. Therefore, a new real-time algorithm for the online detection of flow states is developed to overcome this limitation. For a model-based sensor microphone measurements(More)
The lift response of the separated flow over a wing to different actuator input disturbances is used to obtain linear models useful for closed-loop control design. The wing has a small aspect ratio, a semi-circular planform, and is fully stalled at a 20 o angle of attack. Individual pulse-like disturbances and step-input disturbances with randomized(More)
Active control of separated flows has become a major challenge in recent years. Whereas most of the work published so far is based on simulation studies this paper gives an example of a successful application of a multivariable closed-loop flow control in wind tunnel experiments. A robust H ∞-controller is used to control the spanwise reattachment length(More)