Secondary Loss Generation in a Linear Cascade of High-Turning Turbine Blades

Flow through a linear cascade of high-turning, low aspect ratio turbine blades has been measured in great detail at five planes within the cascade and two downstream in order to trace the generation of stagnation pressure loss in the passage. Five-hole probes were used in the main flow but as it is important to resolve the boundary layers accurately three-hole and single flattened probes were used near the end wall and blade surfaces respectively. End wall shear stresses have been measured using a hot-film probe and an oil-drop viscosity balance technique. Numerical predictions and simple aerodynamic models are used in conjunction with the experimental data to estimate the relative importance of different loss mechanisms, including boundary layer shear stresses and mixing processes.