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Influence of blade passing on the stator wake in a transonic turbine stage investigated by particle image velocimetry and laser vibrometry

Abstract The aerodynamic behaviour of stator and rotor interaction in axial flow turbines is complex and highly unsteady. Particle image velocimetry (PIV) and laser vibrometry (LV) were used to investigate the phenomena observed in a transonic turbine stage operated continuously in a cold-flow test rig. While LV gave basic information on the frequency behaviour of the density fluctuations in the stator wake, stereoscopic PIV was used for investigations of the flowfield vorticity during rotor blade passing. Phase locking of the vortex shedding to the seventh and eighth harmonics of the blade passing frequency was observed.