Investigation of Suction Performance on a Mixed Flow Pump with Semi-Open Casing

Mixed flow pumps exhibit characteristics of both centrifugal and axial flow pumps, with meridional geometry and blade shape playing a crucial role in their hydraulic performance. Tip clearance gap thickness also significantly impacts pump efficiency, cavitation behavior, and pressure fluctuations. This study investigates the influence of tip clearance gap size on the performance and cavitation characteristics of a mixed flow pump with a semi-open casing using Computational Fluid Dynamics (CFD). Cavitation analysis, conducted using the Rayleigh-Plesset model, demonstrates a strong correlation between tip clearance gap thickness and cavitation inception. The results indicate that increasing clearance gap thickness leads to efficiency and head reduction, intensifies tip leakage vortices, and increases cavitation susceptibility. Internal flow analysis further reveals that low-pressure regions expand with increasing clearance gap thickness, causing cavitation within the impeller flow passage.