Influence factors and prediction model of enstrophy dissipation from the tip leakage vortex in a multiphase pump

Abstract

In a multiphase pump, tip clearance is the required distance between the blade tip and the pump body wall of the impeller, forming tip leakage vortex (TLV), causing unstable flow and energy dissipation. In the present work, the enstrophy dissipation theory is innovatively applied to quantitatively study the energy dissipation of the TLV. The flow rate, tip clearance, and inlet gas void fraction (IGVF) play a crucial role in affecting the enstrophy dissipation of the TLV. The results show that increasing flow rate, tip clearance, and IGVF significantly exacerbate the TLV pattern and raise the TLV scale, which gradually raises volume enstrophy dissipation and decreases wall enstrophy dissipation. As the flow rate increases, the separation angle between the primary TLV trajectory and the blade gradually decreases, and widely dispersing the enstrophy dissipation near the shroud. However, as the tip clearance increases, the tip separated vortex scale increases and extends to the suction surface, raising the velocity gradient. Besides, as the IGVF increases, the secondary TLV develops from a continuous sheet vortex to a scattered strip vortex, increasing the significantly increasing the enstrophy dissipation. Considering the flow rate, tip clearance, and IGVF as independent variables, simple and multiple nonlinear regression models have the ability to predict the enstrophy dissipation of the TLV accurately.