Effects of IGVF on the performance and internal energy loss mechanisms of a two-stage booster pump under cryogenic liquid CO 2 condition

Abstract

This study investigates the impact of the inlet gas volume fraction (IGVF) on the hydraulic performance and internal loss characteristics of a two-stage cryogenic liquid CO₂ booster pump. The Gas–liquid two-phase flow is simulated using an Euler–Euler model with the multiple size group (MUSIG), and internal losses are evaluated via a method based on entropy generation. The results indicate that pump efficiency decreases as IGVF increases, with the peak efficiency shifting to lower flow rates. Notably, the primary energy dissipation region fundamentally shifts from the stationary volute at low IGVFs to Impeller 1 at higher IGVFs. In Impeller 1, pressure-side gas accumulation causes severe blockage and peak turbulent dissipation. Conversely, the transition flow channel acts as a critical fluid rectifier via centrifugal phase segregation. It delivers a reorganized, stabilized inflow to Impeller 2, preserving its streamline stability and mitigating energy losses. Furthermore, the intensity of vortices within the impeller increases with higher IGVF, reducing hydraulic efficiency and compromising operational stability. These findings highlight the need for targeted structural optimization in booster pump design to mitigate the impact of gas-phase interactions, given the significant influence of IGVF on the impeller and transition flow channel.