Abstract
The aerodynamic loads on a static airfoil are modified below its stall margin by deliberate formation and regulation of trapped vorticity on the suction and pressure surfaces near the trailing edge. Vorticity accumulation and shedding are effected using a hybrid actuator comprising a miniature two-dimensional passive protuberance having a cross-stream scale that is nominally commensurate with the local boundary layer thickness, and the vorticity flux is regulated using integrated spanwise arrays of equally spaced high aspect ratio synthetic jet actuators. The aerodynamic loads are varied by independent differential control of flux of opposite sense vorticity from both sides of the airfoil that are characterized using measurements of the force/torque, surface pressure, and particle image velocimetry over the suction surface and in the airfoil's near wake. The induced changes in circulation and lift and in the pitching moment are traced to complex transitory changes in vorticity flux associated with the onset and termination of the actuation. These changes are characterized by transitory variations in the balance of flux and shedding of clockwise and counterclockwise vorticities that are triggered, respectively, by actuation on the pressure or suction surfaces. These investigations indicate that hybrid flow control by trapped vorticity, which has the potential to manipulate prestall aerodynamic loads without mechanical control surfaces, may enable novel wing designs.
9 More- Received 23 August 2018
DOI:https://doi.org/10.1103/PhysRevFluids.4.034601
©2019 American Physical Society