Investigation of tip leakage flow in spatial and temporal scales of axial isolated compressor rotor near stall

To conduct detailed investigations about tip leakage flow in spatial and temporal scale at near stall, a total pressure probe, stereo particle image velocimetry (SPIV), dynamic pressure sensors array and validated numerical simulation are adopted at the near stall condition in a large scale iso-rotor compressor. Higher pressure regions are found propagating in circumference at near stall through different measurements technology. Completely different leakage vortex propagation characteristics are found assisted with SPIV technology at design and near stall condition, respectively. The rotor outlet total pressure dominant frequency shows an obviously non-synchronous characteristic, which is inconsistent with shaft frequency and blade pass frequency. The wall static pressure results and the vortex propagation frequency are also mutually confirmed nearly at 213 Hz. To investigate the propagation of pressure wave, an azimuthal mode analysis is adopted to get the spatial circular characteristic of disturbance. Furthermore, numerical results also show that the leakage vortex at near stall has propagated closer to the nearby blade pressure side, vortex broken position has advanced 10–20% chord length distance in the passage when compared with the design condition result. Rotating instability and the leakage vortex maintained a close association with the circulation propagation disturbance. Vortex line and blade frontal line intersection angle changed from 13° to 19° in a swing period.