Stereoscopic particle image velocimetry in a transonic turbine stage

In order to investigate the flow field in axial turbine stages, a continuously operating transonic test turbine facility for high pressure ratios was designed at Graz University of Technology, Austria. This test facility allows optical access to the rotor and to the stator trailing edge. The three-dimensional velocity distribution in the region of stator–rotor interaction was investigated by stereoscopic particle image velocimetry. To obtain the three-dimensional velocity vectors in one plane at the mid-section of the turbine blades, a calibration-based method was used. Light-sheet delivery, seeding and triggering to four pre-defined rotor–stator positions are discussed, and an insight into the rotor–stator interaction is given, including vortex shedding in the stator wake.