Spatio-Temporal Evolution of Tip Leakage Flow in a Low-Speed Axial Compressor

Abstract

Tip leakage flow (TLF) is a critical flow phenomenon governing the efficiency and stability of axial compressors. While its steady-state flow structure is broadly understood, its inherent unsteady nature and spatio-temporal evolution from stable to unstable conditions remain active areas of research. This research characterizes the dynamic behavior of the TLF in a low-speed axial compressor rotor using single-passage and full-annulus delayed detached eddy simulation. By performing mean flow analysis, transient flow analysis, and modal analysis, three dominant modes were identified: (i) vortex shedding after the main tip leakage vortex (TLV) breakdown; (ii) main TLV swing that triggers leading edge spillage; (iii) post-stall compression system resonance. With decreasing flow coefficient, the spatio-temporal scales of TLF increase, and mode (ii) plays the dominant role. The full annulus results show trends similar to those in single passage before the formation of stall cells. The findings elucidate the critical dynamic mechanisms by which the evolving TLF triggers instability, offering valuable insights for accurate prediction and flow control of compressor stall inception.