Fundamentals and Applications of Modern Flow Control

Any active flow control system necessarily includes actuators and, for the case of systems employing feedback control, sensors. The modeling, design, fabrica- tion, and testing of these transducers can be complicated, expensive, and time consuming, often requiring numerous design cycles with less than satisfactory results. The purpose of this chapter is to review recent progress in popular actua- tors and microelectromechanical systems (MEMS) unsteady pressure and shear- stress sensors for flow control applications. The chapter is broken into two parts; a discussion of actuators precedes that of sensors. As with any engineering system, a design cannot proceed without a statement of often conflicting technical require- ments. Therefore each major section begins with a brief discussion of basic termi- nology and design specifications, followed by their specific interplay with potential flow control objectives.