Mechanisms of Endwall Leakage Flows and the Associated Losses in a Linear Turbine Rotor Cascade with Blade Tip-Clearance

摘要

The mechanisms of three-dimensional flows and of the associated losses occurring in the tip endwall region of a linear turbine cascade with tip-clearance are discussed. The clearance gap sizes and the cascade incidences were chosen as the most important variables affecting the mechanisms. Flows close to the endwall and inside the clearance were surveyed in great detail using a micro five-hole Pitot tube of 0.6 mm head size. The results gave very detailed information on the mechanisms, such as leakage flow vectors and pressure distributions throughout the clearance. Interaction of leakage flow with the endwall flow and their associated separation lines, effects of gap size and inlet flow angle on loss generation, and skewness of the three-dimensional endwall flows are also discussed.