Nonlinear active control of turbulent separated flows : Theory and experiments

Flow control is a strongly growing field aiming at modifying fluid flows using actuators and control algorithms. An important part of flow control is the control of flow separation as boundary layer separation increases drag and therefore energy losses and fuel consumption. This thesis focuses on developing control algorithms for flow reattachment using pulsed jets actuators. The first part of this work develops a model identification technique based on experimental data. The models are derived from physical and control theory considerations. They provide a good fit to the data while remaining simple and using few coefficients. The second part of this work uses this models in order to design two different control algorithms : the first one is an optimal feedforward control while the second one is a robust feedback control. The control algorithms have been applied on several experimental setups (LML, ONERA, LAMIH) and their properties have been experimentally tested. The tests were conducted using a simple Arduino Uno for the measurements and computation of the control, showing that the developed method is easy to apply and requires very few computational resources