Three-Dimensional Unsteady Flow Field due to Rotor-Stator Interaction in the Tip Region of an Axial Compressor Stator Passage

This paper reports an experimental study of the three-dimensional unsteady flow field due to rotor-stator interaction in the tip region of an axial compressor stator passage. The measurements were conducted on a low-speed large-scale axial compressor using a 3-component Laser Doppler Velocimetry. Both experimental method and measurement techniques are presented in details. The measurement results indicate that the rotor tip leakage vortex and the rotor wake periodically pass through the tip region of a stator passage, resulting in periodical flow blockages and fluctuations in the stator passage. In the meantime, the wake is catching up with the last rotor leakage vortex. The interaction and the flow mixing between the vortex and the wake occur in a stator passage, leading to more substantial fluctuations in the flow field. The rotor lip leakage vortex has a stronger influence on the downstream endwall flow than the rotor wake. The low-energy fluids from the upstream tend to accumulate toward the pressure surface of a stator blade. The separation flow near the suction surface is found in the rear of a stator passage. The interaction and the flow mixing are observed among the low-energy fluids from the upstream and the separation flow.