Boundary layer transition and separation entails great energy losses and limits the performance of most flow-related devices. It imposes severe limitations not only on the design but it also affects the operation and performance of the devices. Therefore, the control of boundary layer transition and separation or at least its delay is warranted. Passive control techniques, such as geometrical shaping, turbulators and vortex generators or steady active methods such as transpirations through porous plates, holes, slots and slats are the most commonly used in aerospace to delay laminar-turbulent transition or control boundary layer separation. However, passive techniques are by definition “point design” and degrade performance at other operational conditions.

The science and technology of unsteady Active Flow Control (AFC) are becoming more sophisticated as Fluid Dynamics, low order modelling and Control theory merge to enable the design of flow control systems capable of solving challenging real flow control problems.  This graduate course will examine advanced topics in passive and active flow control, placing particular emphasis on “how to perform flow control”.  Vast experimental open- and closed-loop active flow control experience using periodic excitation for transition delay and enhanced mixing and its limitations will be discussed.  State-of-the-art actuator and sensor design and characterization techniques will be covered.  A few closed-loop flow control applications will be analyzed. A modified version of the integral boundary layer equation model will be used to analyze various flow control methods from the point of view of overall system efficiency. Case studies will be presented that describe recent success stories about the implementation of active flow control on advanced flow related systems, not only in aerospace. The course is relevant to both graduate students and industry participants and will also be offered online.