Boundary Layer Control Using Micro-Electromechanical Systems

This study investigated the use of MEMS devices to control the boundary layer separation from a circular cylinder in cross flow. Measurements were accomplished in AFIT's low-speed, 12-inch cross section wind tunnel. Velocity curves integrated for the momentum thickness were the primary means of detecting changes in the flow field. MEMS placed spanwise across the length of the cylinder were actuated in a variety of operating frequencies and at a variety of angular positions relative to the incoming flow. It was the goal to determine which combination of angle and frequency would best serve the purpose of boundary layer control. An optimal angle of 69 degrees was discovered, and the optimal frequency equal to that of the shedding frequency provided the best solution. Of the tests conducted, these conditions allowed nearly a 25% reduction of momentum loss in the cylinder wake.