Session Ce - Separated Flows.
ORAL session, Sunday, November 23
305, Moscone Center
The apparent aerodynamic shape (and thus lift and drag) of a 2-D cylinder is modified in wind tunnel experiments using a spanwise pair of synthetic jet actuators. The interaction of the jets with the embedding flow leads to the formation of closed recirculation regions and thus to an apparent modification of the flow boundary. Smoke visualization experiments demonstrate that the closed recirculating flow regimes near the surface scale with the momentum coefficient and can displace local streamlines well outside the surface boundary layer. Azimuthal distributions of surface pressure measured over a range of jet angles demonstrate that the jets effect substantial increase in lift (up to C_L=0.6) and a reduction in drag (up to 30%). Velocity measurements in the wake of the cylinder demonstrate that these changes are accompanied by vectoring and loss of symmetry. The small scale motions induced by the actuators in the near wake lead to increased dissipation and a reduction in the turbulent kinetic energy.