EXPERIMENTAL-STUDY OF THE 3-DIMENSIONAL FLOW FIELD IN A TURBINE STATOR PRECEDED BY A FULL STAGE

The paper describes the experimental investigation of the three-dimensional flow field through a low aspect ratio, high turning turbine stator preceded by a full stage. This configuration simulates as closely as possible the flow conditions for an intermediate stator in a multistage machine, although the use of cylindrical rotor blades does not reflect typical gas turbine design practice. The inlet conditions to the stator are significantly different from those reported in previous investigations dealing with tests in isolated cascades, e.g., Sieverding (1985); Marchal and Sieverding (1977); Sieverding et al. (1984); Klein (1969); Bindon (1979, 1980); Wegel (1970); and Boletis (1985). The inlet flow field to the stator is characterized by both radial and circumferential gradients. Inlet skew occurs on both endwalls but the overall shape does not resemble those that are generated in isolated cascades by rotating the upstream endwalls. Rotor clearance effects are of predominant importance for the flow field at the tip endwall region. The flow field is explored by means of double head four-hole pressure probes in five axial planes from upstream to far downstream of the stator. The results are presented in the form of contour plots and spanwise pitch-averaged distributions.