Circulation Control Using Arrays of Fluidically Oscillating Jets

Controlled modification of an airfoil’s circulation to effect significant lift increments has been commonly realized by exploiting the Coanda effect near its trailing edge using a nominally 2D tangential wall jet over a bluff trailing edge or the airfoil’s flap. The present experimental investigation explores the utility of segmented Coanda actuation using spanwise distributions of fluidically oscillating wall jets integrated into the rounded trailing edge of a 2D supercritical airfoil model, and their circulation control performance is compared with 2D actuation at low angles of attack ([Formula: see text]) and [Formula: see text]. The actuation is characterized using the mass flow rate coefficient [Formula: see text] and a variant of the conventional momentum coefficient [Formula: see text] that measures the magnitude of the resultant aerodynamic force effected by the 2- and 3D actuation on the aerodynamic platform in the absence of a crossflow. It is shown that while 3D actuation yields somewhat higher lift increments at [Formula: see text], the increments induced by 2- and 3D actuation are comparable at higher [Formula: see text]. However, the induced drag increments by the 3D actuation are significantly lower than the corresponding 2D increments over the entire range of the present measurements, even when the actuation force is deducted. Finally, when [Formula: see text] is scaled by the actuation’s active area and its spanwise duty cycle, the variations of the induced lift and drag increments with the scaled [Formula: see text] indicate a unified relationship for the different 3D arrays.