Three-dimensional spatial-temporal evolution and dynamics of the tip leakage vortex in an oil–gas multiphase pump

To explore the spatial-temporal evolution and dynamics of the tip leakage vortex (TLV) in an oil–gas multiphase pump, the TLV was captured accurately and vortex structures were analyzed in detail under different operating conditions. Results revealed that the TLV structures included the leading edge vortex, tip separation vortex, primary tip leakage vortex (PTLV), secondary tip leakage vortex (STLV), and trailing edge vortex. In one impeller rotation period, the three-dimensional spatial-temporal evolution of the TLV could be divided into three stages: splitting, shrinking, and merging. In this process, the spatial-temporal evolution of the PTLV and STLV was closely correlated. In addition, the relative vorticity transport equation was used to analyze the TLV near the tip clearance region of the impeller. Results showed that the relative vortex stretching item (RVS), Coriolis force (CORF), and viscous diffusion (VISD) jointly controlled the spatial-temporal evolution of the TLV and were the dynamic sources of variation in the vorticity and trajectory of the TLV. In particular, the gas phase changed the distributions of the RVS, CORF, and VISD on the intensity isosurface of the TLV and had a significant effect on the spatial-temporal evolution of the TLV.