Abstract
In this paper the study of an axial turbine with a supersonic rotor has been performed for a full stage turbine. The state-of-the art supersonic stages include supersonic stators that create shock waves that enter the rotor stage disturbing the flow. The current study proposes a semi-shockless approach which consists of using a supersonic rotor (altogether with a subsonic stator) and force the generation of the shockwave outside of the rotor passage. A method to design supersonic rotors is presented by using blade deflection angle and Mach number profiles along the blade length. Several 2D simulations using the SU2 solver were performed to evaluate the transition behavior at supersonic flow with different outlet pressures. The proposed rotor geometry allows to control by design the position and intensity of the generated shockwave. Thus, it was chosen to position the shock wave at the end of the rotor blade and to minimize its intensity. As an additional feature, the stator blades were replaced by a volute in order to reduce the quantity of components used in a full stage turbine for turbine designs having a volute just before the stator. A full stage 3D CFD analysis was performed using Ansys CFX solver. This approach has helped for the design of supersonic turbine stages with lower shock wave interactions between components.
