SUMMARY

The aerodynamic characteristics of an airfoil are modified using active fluidic-based flow control over a range of angle of attack with specific emphasis on control in the absence and presence of stall. The present investigations have focused on the utility of transitory, pulsed-fluidic actuation which is demonstrated on a VR-12 airfoil. The earlier work has focused on mitigation of stall at moderate to high angles of attack using pulsed actuation near the leading edge by combustion-powered actuators. It is shown that the actuation on static and pitching/plunging model effects rapid, accelerated flow re-attachment and consequently increased lift performance and improved damping stability. The proposed PhD research builds on the earlier work and seeks to extend the operability of active flow control to moderate and low angles of attack when the base flow is fully-attached for regulation of the aerodynamic loads with the objective of enabling mitigation of structural vibrations. Such control would require bi-directional manipulation of the aerodynamic loads and will be accomplished using independently controlled high aspect ratio spanwise trailing edge actuation jets on the pressure and suction sides. Transitory actuation will be provided by bi-stable fluidically switched jets that will temporally manipulate the circulation around the airfoil and the airfoil's Kutta condition to alter the aerodynamic forces. The coupling mechanisms between the actuation and the aerodynamic loads will be investigated in detail using phase-locked particle image velocimetry, direct measurements of the time-dependent loads, and vibration measurement using embedded accelerometers.