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, and can regulate tip leakage vortex (TLV), causing unstable flow and energy dissipation. However, there are few studies on the energy dissipation caused by the TLV. In the present work, the enstrophy dissipation theory is innovatively applied to quantitatively study the energy dissipation of the TLV. The flow rate ( Q) , tip clearance ( Rtc) , and inlet gas void fraction ( IGVF ) play a crucial role in affecting the enstrophy dissipation of the TLV. The results suggest that increasing Q , Rtc , and IGVF significantly exacerbate the TLV pattern and raise the TLV scale, which gradually raises volume enstrophy dissipation and decreases wall enstrophy dissipation. The maximum pressure load in the impeller occurs at the 0.5 chord, where a strong TLV is generated, leading to significant enstrophy dissipation. As the flow rate increases, the separation angle between the primary TLV (PTLV) trajectory and the blade gradually decreases, and widely dispersing the enstrophy dissipation near the shroud. However, as the tip clearance increases, the tipseparated vortex (TSV) scale increases and extends to the suction surface, raising the velocity gradient. Besides, as the IGVF increases, the secondary TLV (STLV) develops from a continuous sheet vortex to a scattered strip vortex, increasing the pressure fluctuation intensity. Considering the flow rate, tip clearance, and IGVF as independent variables, simple and multiple nonlinear regression models for the enstrophy dissipation are established.