Active Boundary Layer Control with Fluidic Oscillators on Highly-Loaded Turbine Airfoils

The trend in jet engine development to reduce airfoil count is still ongoing in order to reduce weight and cost without sacrificing performance. In this context highly loaded airfoils have successfully been developed in the last decade. A better understanding of boundary layer transition and separation phenomena on turbine blades in combination with periodic incoming wakes was the key for this success. The Institute of Jet Propulsion of the Universitat der Bundeswehr in Munich, Germany was heavily involved in the research effort from the very beginning. Since the flow gets prone to massive flow separation, associated with drastic increase of total pressure losses, further increased aerodynamic loading can only be achieved when applying passive or active methods to control the boundary layer on the blade surface. Reviewing shortly activities with passive devices this paper gives an overview of the research on active boundary layer control with fluidic oscillators on turbine blades.