Analysis of unsteady tip leakage flow in an axial compressor rotor using dynamic mode decomposition

Tip leakage flow (TLF) is an important flow structure in the compressor, and it has a significant effect on the efficiency and stability of the compressor. In this study, dynamic mode decomposition (DMD) is used to study the spatiotemporal flow structure of the tip leakage flow in a compressor rotor. The high-fidelity flow field calculated via the delayed-detached eddy simulation (DDES) of an axial compressor rotor is used as the input dataset for the DMD algorithm. The results show that the unsteady motion of the tip leakage vortex (TLV) is quite different at its generation, development, and dissipation phases. Additionally, three typical unsteady structures, the oscillation of the primary TLV, the TLV breakdown, and the unsteadiness of the unsteady blockage cell, is identified by the DMD modes. Unsteady motions also largely affect the vortex structure and loss generation, especially after the vortex breakdown. The spatiotemporal structure identified by DMD provides a new understanding, which could be helpful for the modeling or flow control of the TLF.