Research on the dynamic characteristics and distributions of bubbles in a disc pump under gas-liquid two-phase flow conditions

Bubble dynamics and distributions within a disc pump under gas-liquid two-phase flow conditions are investigated in this study. The experimental results show that the pump head and efficiency remain at 72% and 82% of the performance under single-phase flow conditions when inlet gas void fraction (IGVF) is as high as 9%. High-speed photography is used to visualize the internal flow pattern of the pump, and the obtained images reveal that the bubble sizes are relatively small and that the internal flow pattern is close to that under single-phase flow conditions when IGVF ≤ 7%. When IGVF ≥ 9%, reverse flow is observed but pump performance remains stable. Numerical simulations are then carried out, and the results are consistent with the experimental results with maximum performance difference less than 4.5%. It is revealed that the reverse flow is located in shroud and hub areas, and middle bladeless area is the main flow channel, which is the reason why pump performance remains stable when reverse flow is presented. Bubbles are distributed mainly at the impeller outlet, especially on the right-hand side of the volute, because this area is subjected to the maximum inward pressure gradient force, which dominates and causes the bubbles to move inward. Statistical analysis of internal pump bubbles revealed that most of the bubbles (approximately 60%) are distributed in the shroud area, followed by the hub area (approximately 30%); the fewest are in the middle of the bladeless area (approximately 10%); and large bubbles tend to move to the shroud side when the IGVF is increased.