14th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
Spectral proper orthogonal decomposition (SPOD) is performed on the near-stall tip leakage flow of a low-speed rotor. The data used for the SPOD analysis is obtained by delayed-detached eddy simulation (DDES), which is validated against experimental data. The flow quantities of interest include the near-tip axial velocity and the blade surface pressure. Results show that the near-stall flow field of the investigated rotor is governed by two tip leakage vortices (TLVs). The main TLV initiated from the leading edge creates a tip blockage cell and exerts an unsteady force on the blade pressure surface. Its modal component is dominated by the leading modes at low frequencies. The secondary TLV originated from the mid-chord creates a weaker unsteady force on the blade suction surface, and its modal component is more complex than the main TLV. These findings improve the understanding of tip leakage flow on affecting compressor aerodynamic and aeroelastic stability.