Active flow control on bluff bodies with distinct separation locations

Active flow control (AFC) studies are currently in progress at The University of Arizona utilizing both computational and experimental efforts aimed at optimizing the parameters affecting pressure drag. The two-dimensional wind tunnel tests and numerical models use existing tilt-rotor airfoils in their representative aircraft hover orientation to the flow as the test articles. Zero mass-flux oscillatory blowing through slots at various locations on the airfoil achieves significant reduction in download. For the numerical simulations, a semi-implicit finite element solver with unstructured mesh capability was used for the threedimensional, time-dependent flow fields. Two large eddy simulation (LES) turbulence models were used; the constant and also the dynamic coefficient Smagorinsky models. Various numerical resolutions for the forcing slot as well as the computational domain were tested. The airfoil configuration, actuators and slot parameters affecting the interaction of the forced shear layer with the downstream wake continue to be investigated. The results show the impact of each of these control parameters on the flow field and the resulting download. Planned studies will further refine this understanding with the goal of achieving a significant download reduction using the optimum or minimum actuator requirement.