The Influence of Tip Clearance on the Performance of a High-Speed Inducer Centrifugal Pump under Different Flow Rates Conditions

The influence mechanism of the blade tip clearance (TC) of an inducer on the performance of a centrifugal pump at high speed was researched under different flow rate conditions in this work. An experiment on the pump's external performance was carried out, and numerical calculation was also performed under four different TCs. The full characteristic performance curves, static pressure and pressure pulsation distributions of the pump were obtained. Through the research and analysis, it was found that the influence of the TC on the efficiency and the head of the centrifugal pump are related to the flow rate. Under the influence of a large flow rate, the increase in the TC is helpful to improve the efficiency and the head of the pump. The increase in the TC helps to weaken the gap jet effect on the inducer. The inlet jet of the inducer, caused by TC leakage, will form a low-pressure vortex zone at the inlet of the inducer. The splitter-bladed inducer's pressure pulsation is affected by the TC. The peak pressure pulsation at the monitoring point at the short blades is larger than that at the long blades. With the increase in TC, the cavitation degree at the inlet of the long blade of the inducer is decreased, while the cavitation degree at the short blade is deepened. It is also found that the TC has little effect on the radial force of the inducer and the impeller. These results will provide the design basis for the tip clearance of an inducer.