Modification of global properties of a mixing layer by open/closed loop actuation

Open- and closed-loop control of a turbulent mixing layer is experimentally performed in a dedicated large scale, low speed wind-tunnel facility. The flow is manipulated by fluidic micro-jet actuators integrated in the trailing edge of the splitter plate. Sensing is performed using a rake of hotwire probes downstream of the splitter plate in the mixing layer. The control goal is the manipulation of the spreading rate and of the virtual origin of the mixing layer. The underlying physical mechanisms employ a wide range of frequencies. The calculated Reynolds number based on momentum thickness of the boundary layer at the trailing edge is around Re=500-2000 depending on the mixing layer configuration. Control authority is presented using smoke visualization, Particle Image Velocimetry (PIV) and hot-wire measurements of local velocity.