Investigation of Turbine Cascade Blades With Part-Span Sweep With an Open End

The present paper focuses on a low-speed computational investigation into the application of backward sweep for application on a typical low-pressure turbine rotor blade. A quasi-two-dimensional linear cascade using T106 profile, was investigated using flow solver Star-CCM+®. Three backward-swept tip modifications (axial sweep, tangential sweep, and a combination of both) have been applied to the baseline profile from 90%–100% span, the rest of the 90% of the blade remained straight and orthogonal to the cascade mainstream flow. The blade stacking axis near the tip was shifted away from the mainstream flow for all three sweep configurations at 15°, 30°, and 45° from the blade axis plane. The impact on pressure losses, tip blade loading, and reduction of tip leakage flow and associated vortices has been analyzed. As the leakage vortex increases in size, causing enhanced blockage to the passage flow, rotor work extraction capability decreases. The application of backward sweep to the blade tip increases the tip cross flow rate, but reduces the turbulent kinetic energy (TKE) across the tip gap. The reduction of TKE of the leakage flow, results in a smaller and less intense tip leakage vortex even though the cross flow rate increases. Minimizing the leakage vortex size and intensity reduces total pressure losses and thereby improves rotor efficiency.Copyright © 2013 by ASME