Aerodynamic Control at Low Angles of Attack using Trapped Vorticity Concentrations

The aerodynamic characteristics of a swept wing are significantly altered at low angles of attack (when the baseline flow is fully attached) by vorticity concentrations that are engendered using integrated hybrid actuators each comprised of a miniature [O(0.01c)] small obstruction and a synthetic jet actuator. The present work demonstrates that the presence of controllable trapped vorticity concentrations near the leading and trailing edges on the pressure side of the airfoil can lead to a significant simultaneous increase in lift and reduction in drag compared to the baseline airfoil (L/Dp increases by a factor of 2.6 at α = 6°). It is also shown that the aerodynamic performance can be maintained at substantially reduced actuation power when the actuation waveform of the trailing edge actuator is pulse-modulated at a frequency that is commensurate with the unstable frequency of the wake.