Features of Transition Mechanism Triggered by Synthetic Jet in a Low Pressure Turbine Decelerating Boundary Layer

Environmental concern, thus higher efficiency, is a leading theme for modern aero jet-engine design. The low pressure turbine blades are subject to a wide range of Reynolds number that may reach very low values associated with altitude, which may induce massive flow separation and finally yield dramatic loss increase. The solution here analysed is based on the use of a synthetic jet, a pulsating zero-net mass-flow jet introducing a local thin layer of vorticity within the laminar boundary layer which triggers transition thus preventing flow separation. Unsteady RANS have been carried out in a controlled environment. The active control device has been applied to a decelerating boundary layer subject to an adverse pressure gradient typical of high-lift LPT. Simulations have been performed in order to analyse the boundary layer development and results are compared with available experiments. The effect of jet parameters such as frequency and amplitude have been considered.