Investigations on the effect of tip clearance gap and inducer on the transport of air-water two-phase flow by centrifugal pumps

•Two-phase flows were studied experimentally and numerically in a centrifugal pump.•The ability of simulations to accurately predict all flow features was analyzed.•Influence of the tip clearance gap and inducer on the performance were studied.•Two-phase regimes and BSDs were identified with a high-speed camera.•Increasing the gap or adding the inducer improved two-phase mixing and BSDs.