Abstract: Tip leakage vortices (TLVs) in a semi-open gas-liquid mixed transport pump are often accompanied by a large number of bubbles, which induce instability in pump operation. This study numerically simulates the flows in a three-stage semi-open mixed flow pump using an Euler-Euler inhomogeneous two-phase flow model and a MUSIG bubble distribution model to study the dynamic behaviors of the TLVs with bubbles. High-speed camera technology is used to capture their trajectory, structure, and developing process in an impeller blade period. The results indicate that in the vicinity of the blade tip clearance, the largest dissipation of vorticity is caused by the Coriolis force term, followed by the stretch-twist term. Under gas-liquid two-phase conditions, the magnitudes of the expansion-contraction term and the diagonal torque term decrease by an order of magnitude compared to the first two terms, while they increase with the increase in inlet gas volume fraction (IGVF). Bubble accumulation zones in the impeller affect the position of vortex dissipation zones, and the rotation of the impeller is the main cause of inducing vortex dissipation.

Key words: mixed flow pump, gas-liquid two-phase flow, vortex dynamics, numerical simulation