Interaction Mechanisms between Tip Leakage Flow and the Passage Vortex in a Linear Turbine Rotor Cascade

摘要

In order to study the loss generation mechanisms due to the tip-leakage flow in turbine rotor passages, extensive traverse measurements were made of the three-dimensional flows in a low-speed linear cascade for various tip-clearance sizes and for various cascade inlet flow angles (or incidences). Effects of the leakage flow on the cascade downstream flow fields and interactions between the leakage flow and the passage vortices were discussed in detail based on the traverse measurements and flow-visualization tests in terms of secondary flows and the associated losses. Other traverses of the tip-casing endwall flows were also performed, both inside and outside the tip-clearance gap, using a micro five-hole pitot tube to reveal the axial development of the interaction throughout the cascade passage. Overall loss characteristics of the present high-turning cascade with blunt leading- and trailing-edges were obtained and compared with those predicted by the Ainley-Mathieson method.