Actuation of Passive Flaps Modeled after Shark Scales in a Steady Laminar Boundary Layer Separation Bubble*

Reducing flow separation is of great interest in the field of fluid mechanics to reduce drag and improve the overall efficiency of aircraft. This project seeks to investigate passive flow control using shortfin mako shark inspired microflaps in a laminar boundary layer separation bubble. Microflaps actuated by reversing flow have the potential to be a robust means of controlling flow separation at various Reynolds numbers.  To generate a controlled adverse pressure gradient, a rotating cylinder induces separation at a chosen location within a flat plate laminar boundary layer, ranging from Re = 170,000 to Re = 280,000. Within this thick boundary layer, DPIV is used to measure the flow characteristics. The goal is to better understand the overall mechanism by which shark scales are able to reduce reversing flow with the ultimate aim of fabricating man-made surfaces suitable for real aircraft applications. Results show that microflaps successfully reduced the amount of time-averaged backflow when compared to flat plate cases.