Experimental study on flow phenomena induced by trailing edge shapes for a transonic high pressure turbine cascade

The present study focuses on the influence of the trailing edge shape and on the development of coherent structures in the transonic flow of a turbine blade passage.Experiments were performed in the High-speed Cascade Wind Tunnel of the University of the Bundeswehr Munich on a high pressure turbine linear cascade.Enginerelevant flow conditions are examined at a constant exit Reynoldys number of Re 2th = 1,200,000 and a range of exit Mach numbers from Ma 2th = 0.80 to 1.10.The aerodynamic characteristics of the highly unsteady flow is qualitatively investigated using a five hole wedge probe and Particle Image Velocimetry (PIV).By means of a Proper Orthogonal Decomposition (POD) analysis, dominant flow structures are extracted.The near wake flow and shear layer dynamics as well as the evaluation of the wake downstream of the two trailing edge designs are examined.The results show performance benefits due to the mitigation of coherent structures for exit Mach numbers below Ma 2th = 1.00 for the profiled trailing edge geometry.For higher exit Mach numbers the round trailing edge has a performance advantage as the strength of the main shock increases and seems to play a dominate role on the integral losses.