Study on gas–liquid two-phase flow in the suction chamber of a centrifugal pump and its dimensionless characteristics

Highlights: • Identify 9 gas–liquid two-phase flow patterns in the suction chamber. • Reveal the mechanism of gas–liquid two-phase flow in the suction chamber. • Establish the relationship between the flow patterns and dimensionless characteristics. • Establish the relationship among the bubble size, number of bubbles and working conditions. The suction chamber is one of the important components of the centrifugal pump. The flow in the suction chamber has great influence on the hydraulic efficiency of the impeller. In order to study the law of gas–liquid two-phase flow in the suction chamber, the flow patterns were photographed by two cameras. The external characteristics of the pump were measured under different working conditions. At the same time, the gas–liquid two-phase flow in the centrifugal pump was numerically simulated by FLUET. The simulation results agreed well with the experimental results. Nine flow patterns in suction chamber were identified, and the relationship between the flow patterns and dimensionless characteristics of the pump was established. For the device studied in this paper, the flow pattern in the suction chamber depends mainly on the specific capacity and inlet gas volume fraction. The critical value of inlet gas volume fraction (IGVF) between bubbly flow and plug flow is about 1.00%, and the critical value of IGVF between plug flow and stratified flow is about 4.80%. When the IGVF exceeds 6.20%, the phenomenon of gas locking will appear in the pump. The statistical results of the average bubble diameter and number of bubbles indicate that, in the pulsating bubbly flow and steady bubbly flow, there exists the bubble coalescence enhanced point (IGVF = 0.74%) and the bubble coalescence weakened point (IGVF = 0.44%), respectively.