Using single-passage and multi-passage caculation models

large eddy simulations were conducted to study the unsteady oscillating features of internal flow field in a two-dimensional moving compressor cascade during the throttling process. The changes of vortex structure and oscillating frequency were analyzed. The resutls show that at working conditions with larger mass flow rates

two unsteady oscillations resulted from flow around leading edge and separation on blade suction surface coexist. Both frequencies almost keep constant. Flow structures of separation on suction surface are of small scale. At working conditions near stall limit

large scale separations occur on suction surface. The oscillating frequency decreases dramatically

lower than blade passing frequency.