Design and Commissioning of a Transonic Test Section for the Investigation of Shock Wave-Film Cooling Interactions

Transonic turbine flows are usually characterized by trailing-edge shocks. The oblique shock wave generated at the pressure side of an airfoil impinges on the suction side of the adjacent blade/vane, where it interacts with the boundary layer or cooling film. The present study deals with the design of a generic transonic test rig, which reproduces this kind of interaction under conditions similar to those found in real engines. The design of the set-up was strongly influenced by the requirement to use a Schlieren-System for flow visualization and an Infrared-Thermography-System for heat transfer measurements. A supersonic nozzle design is presented, which allows setting the desired Mach-number distribution and controlling the shock formation in the supersonic test section. The geometry of the supersonic part of the transonic test section has been designed using the “Method of Characteristics”. Viscous effects were taken into account by CFD-studies. First experimental results, in terms of static pressure distributions and Schlieren-images, show excellent agreement with the predicted flow behavior.