Tham khảo tài liệu 'the mems handbook mems applications (2nd ed) - m. gad el hak episode 2 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Towards MEMS Autonomous Control of Free-shear Flows 15-29 Control of Separation over Low-Reynolds-Number Wings Recently researchers from the University of Florida have proposed a MEMS system for controlling separation at low Reynolds numbers. The primary motivation of the proposed system was to enhance the lift-to-drag ratio in the flight of micro-air-vehicles MAVs . Because of their small size a few centimeters characteristic size and low speed MAVs experience low Reynolds number flow phenomena during flight. One of these is an unsteady laminar separation that occurs near the leading edge of the wing and affects the aerodynamic efficiency of the wing adversely. Figure displays a schematic of the proposed control system components and test model geometry. The main idea is based on the deployment of integrated MEMS sensors and actuators near the leading edge of an airfoil or wing section. Additional sensor arrays are to be used near the trailing edge of the wing. The leading edge sensors are intended for detection of the separation location in order to activate those actuators closest to that location for efficient control as discussed previously. On the other hand the trailing edge sensors are to be utilized to sense the location of flow reattachment. In this manner it would be possible to adapt the magnitude and location of actuation in response to changes in the flow and thus for instance maintain the flow attached at a particular location on the wing. The ultimate benefit of such a control system is the manipulation of the aerodynamic forces on the wing for increased efficiency as well as maneuverability without the use of cumbersome mechanical systems. In actual implementation the University of Florida group adopted a hybrid approach whereby conventional-scale piezoelectric devices were used for actuation and MEMS sensors were used for measurements. Additionally it appears that because of the difficulty in detecting the instantaneous separation .
