A Comparison of Secondary Flow in a Vane Cascade and a Curved Duct

This paper describes an experiment performed to measure the aerodynamic characteristics of the three-dimensional flow through a linear cascade of turbine vanes. The three-dimensional cascade flow is compared to the three-dimensional flow through a duct with a shape similar to the cascade passage shape. The measurements provide a description of the cascade flow and of the duct flow. By comparing the viscous flows for these two geometries, the usefulness of the duct shape for simulating cascade aerodynamics is evaluated. Except in the leading edge region, the qualities of the two flows are very similar. However the secondary flow is stronger in the duct passage than in the vane cascade passage. The effect on the cascade passage flow of the horseshoe vortex generated around the leading edge of each vane is shown to be limited to the region near the leading edge/endwall junction.