Studying on the influence of the annular groove position on the cavitation performance of high-speed inducer

To suppress the cavitation instability caused by the leakage vortex at the tip clearance of the high-speed inducer, this study establishes a structure (i.e., annular groove) at the upstream boundary of the high-speed inducer that can absorb the leakage vortex, and 6 sets of design projects are determined, including the initial plan and the axial distance of 0 mm, 2.5 mm, 5 mm, 7.5 mm, and 10 mm, respectively. The effects of annular grooves on cavitation performance under different schemes are studied through a combination of experiment and numerical calculation. The results show that cavitation tends to occur at the position where the leading edge of the suction surface of the inducer intersects the shroud and the bubbles volume is distributed in gradient. Vortex belt is formed at the inlet of the inducer. The axial position of the annular groove relative to the inducer is an important parameter suppressing the occurrence of clearance leakage vortex cavitation, asymmetric vortex cavitation and rotating vortex cavitation. In the proper position, annular groove can significantly suppress the bubbles incipient and improve the cavitation performance of the inducer. It can improve the head of the centrifugal pump effectively under the condition of little effect on centrifugal pump efficiency. However, at other positions, the annular groove cannot improve the cavitation performance of the centrifugal pump, indicating the annular groove has an axial optimal position in inhibiting cavitation and improving cavitation performance of the inducer, at this time L1=0 mm.