WP-4 Internal Flows—Turbine

Modern HP turbine stages consist of highly loaded aerofoils, including transonic and even supersonic flow regions. In terms of stators a normal shock wave in the passage throat chokes the flow, stabilizing the flow conditions at the operating point. In addition to these flow phenomena, the strong acceleration along the early suction side leads to a relaminarisation of the flow, which in turn has a strong impact on the size of the shock induced separation bubble. Finally, the injection of film coolant via rows of cooling holes further influences the boundary layer state. As heat transfer and film cooling effectiveness are of crucial importance in high pressure turbines, an in-depth understanding of transition mechanisms is needed for a competitive design. The main objective was to study transition location effects (from natural transition to fully turbulent) on separation size, shock structure and unsteadiness. The transition interaction with cooling flow was a real challenge for the TFAST project. This research delivered new knowledge, which is crucial for further improvement of HP turbine stages. As transition control devices AJVG and disturbance strip were used.