Department of Mechanical and Mechatronics Engineering, University of Waterloo
Stability, transition, and response to controlled perturbations in separating-reattaching shear flows
A brief overview of ongoing and recent research projects in the Fluid Mechanics Research Laboratory will be provided. These projects include experimental investigations of airfoil performance in low Reynolds number flows, flows over complex cylindrical geometries common to mechanical systems and civil structures, flow induced vibrations, and flow control.
The main presentation will focus on separating-reattaching flows on airfoils and their control. Recent advancements in small and medium scale wind turbines as well as unmanned aerial vehicles brought about an increased interest in airfoil operation at low chord Reynolds numbers (below about 500,000). Airfoil performance in this domain of Reynolds numbers differs significantly from that common to high Reynolds number flows. In particular, a laminar boundary layer on the suction side of the airfoil often separates even at low angles of attack, which detrimentally affects airfoil performance. The severity of airfoil performance degradation depends significantly on separated shear layer development. The shear layer is inherently unstable and undergoes transition to turbulence downstream of separation, which can lead to flow reattachment and the formation of a separation bubble. Recent results from a series of experimental studies will be presented to provide a new outlook on the attendant transition process and the response of such flows to controlled excitation.