3-DIMENSIONAL INTERACTIONS IN THE ROTOR OF AN AXIAL TURBINE

This article presents a study of the development of the three-dimensio nal flowfield within the rotor blades of a low-speed, large-scale axia l flow turbine. Measurements have been performed in the rotating and s tationary frames of reference. Time-mean data have been obtained using miniature five-hole pneumatic probes, whereas the unsteady developmen t of the now has been determined using three-axis subminiature hot-wir e anemometers. Additional information is provided by the results of bl ade-surface flow-visualization experiments and surface-mounted hot-fil m anemometers. The development of the stator exit flow, as it passes t hrough the rotor blades, is described. Unsteady data suggest that the presence of the rotor secondary and tip leakage flows restricts the re gion of unsteady interaction to near midspan when the stator wakes and secondary flows are adjacent to the suction surface. Surface-mounted hot-film data show that this affects the suction-side laminar-turbulen t transition process.