INFLUENCE OF COOLING ON THE TRANSITION LOCATION IN A STRAIGHT HIGH PRESSURE TURBINE CASCADE

Abstract

This paper presents experimental investigations of a straight high pressure turbine cascade with main focus on the transition location. The design of the turbine blade intends to stabilize the boundary layer in the acceleration region to achieve a laminar boundary layer at the shockwave boundary layer interaction. The indispensable usage of film cooling in a high pressure turbine upstream of the interaction zone can influence this flow regime. The experimental investigations were performed at the Wind Tunnel for Straight Cascades (EGG), G¨ottingen. The investigations were conducted at different Mach numbers and coolant mass flow ratios. Presented are results of infrared and hotfilm-sensor measurements to detect the boundary layer state. The flow field is shown by applying Schlieren technique, pressure taps and unsteady pressure sensitive paint. The results of this investigation will reveal the influence of the cooling on the transition location with respect to different Mach numbers.