Abstract: Experimental and computational results for two configurations which benefit from flow separation control are presented. Both configurations operate at low Reynolds numbers, on the order of 10,000, characterized by laminar flow, often where separation is unavoidable. The first, a flapping-wing propelled micro air vehicle (MAV), consists of a biplane pair of wings flapping in counterphase located downstream of a larger stationary wing, and it is shown that flow entrainment from the flapping wings suppresses stall over the stationary wing, greatly improving the MAV performance. This is experimentally substantiated both qualitatively and quantitatively. The second configuration, a flapping-wing hydropower generator, consists of two flapping wings arranged in a tandem configuration. Numerical results indicate that optimal performance of the device occurs in the presence of massive stall, as long as the flapping motion is properly matched to the convection of the dynamic stall vortices. For both configurations, simplified panel code and Navier-Stokes computations are presented to assist in the assessment of the major geometric and flow parameters affecting the operation of the devices.

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