SUBJECT: Ph.D. Proposal Presentation
BY: John Kearney
TIME: Tuesday, December 3, 2013, 3:00 p.m.
PLACE: Love Building, 210
TITLE: Aerodynamic Control using Distributed Active Bleed
COMMITTEE: Dr. Ari Glezer, Chair (ME)
Dr. Mark Costello (ME/AE)
Dr. Marc Smith (ME)
Dr. Marilyn Smith (AE)
Dr. Bojan Vukasinovic (ME)


The aerodynamic forces and moments on a static and a dynamically oscillating 2-D airfoil model are controlled in wind tunnel experiments using distributed active bleed, driven by pressure differences across the airfoil surfaces and regulated by low-power louver actuators. The bleed interacts with outer flows to effect time-dependent variations of vorticity flux and thereby alters the local flow attachment, resulting in significant changes in lift and pitching moment at static pre- and post-stall angles. The flow field over the airfoil is measured using high-speed PIV, resolving the dynamics and characteristic time-scales of vorticity production and advection that are associated with transient variations in lift and pitching moment. It is shown that time-periodic bleed actuation can improve the lift hysteresis and negative damping characteristics during oscillatory pitching by affecting the shedding of the dynamic stall vortex and the ensuing flow attachment during the downstroke. During plunging oscillations, bleed actuation is shown to significantly suppress vertical motion at pre-stall and post-stall angles. Building on these results, this proposal seeks to investigate the physics of bleedís interaction with outer flows in unsteady environments and to extend its application over a range of reduced pitching frequencies and plunge velocities.