Reasons for the instability of small flow rate in high-speed centrifugal pumps

The main reasons for the small flow instability phenomenon in high-speed centrifugal pumps are the swirling flow generated at the outer diameter of the leading edge of the inducer, the backflow of the centrifugal wheel, the secondary flow in the impeller channel, the wake jet structure and flow separation in the impeller channel, and the secondary flow at the impeller outlet that occurs when the impeller and volute work together. These factors not only affect the flow field distribution of high-speed centrifugal pumps, but also consume a large amount of energy, resulting in a decrease in head and efficiency in the low flow area. Therefore, it is easy for the characteristic line of high-speed centrifugal pumps to show a positive slope rise, leading to instability in low flow conditions.