Static-mixer-assisted inlet flow homogenization for stabilizing high-speed multiphase pumps under high gas loading

High inlet gas volume fractions (IGVF) induce severe buoyancy driven phase segregation in high-speed multiphase pumps, leading to massive vortex-induced gas-locking and sharp efficiency collapse. To elucidate and address this fundamental hydrodynamic bottleneck, this study investigates a static-mixer-assisted inlet flow homogenization strategy. By utilizing a structural flow-conditioning module strictly as an experimental boundary regulator, the internal response of the pump rotor to restructured upstream two-phase topologies was quantitatively evaluated. Optical diagnostics confirm that this spatial pre-conditioning significantly improves phase uniformity, increasing the inlet mixing index from 0.05–0.20 to 0.35–0.60. High-speed visualizations demonstrate that transitioning segregated slugs into dispersed micro-bubbles geometrically minimizes gas-phase inertia and interphase slip. This transformation grants the dispersed phase exceptional fluid followability and successfully mitigates massive gas capture by the tip-leakage vortex (TLV) within the rotating channels. Furthermore, bubble-size statistics reveal that the internal dispersed state is dynamically governed by the competition between rotor-driven turbulent breakup and gas-enhanced coalescence. Ultimately, by fundamentally suppressing severe internal hydraulic dissipation, this strategy yields a highly positive thermodynamic net benefit. It recovers the overall system efficiency from approximately 16% to over 20% at the extreme 25% IGVF boundary, thereby robustly broadening the stable gas-handling envelope.