Abstract: In order to analyze the influence of transition flow channels of different shapes on the cavitation characteristics of a tandem high-speed centrifugal pump, the second stage of a certain type of series high-speed centrifugal pump was taken as the research object. Based on the Zwart-Gerber-Belamri cavitation model in ANSYS Fluent, RNG k-ε two-equation turbulence model is used to compare and analyze the pressurization value, blade cavitation area, and cavitation volume in the flow channel under different cavitation numbers of annular and spiral transition channels under the same working conditions. The results show that the pressure increase value of the Secondary pump of the spiral transition channel is increased by about 8.5% in the flow range of 32 000~64 000 L/h, and the efficiency is improved by about 3%~6% under the large flow condition (q_V>52 000 L/h). When the secondary impeller is completely cavitated, the cavitation area on the back of the secondary impeller blade in the spiral transition channel and the cavitation volume in the channel decreases to a certain extent compared with the annular transition channel. Consequently, it can be seen that the helical transition flow channel inhibits the generation of cavitation bubbles in the impeller blade and improves the anti-cavitation performance of the secondary impeller.

Key words: inter-stage flow channel, numerical simulation, secondary impeller, cavitation number, cavitation volume