Numerical Simulation and Experimental Study of Cavitation and Flow Characteristics of Axial Pumps

This study utilizes numerical calculations and experimental studies to analyze the cavitation characteristic law and performance of an agricultural irrigation axial flow pump with a specific rotational speed of 735 at 0.2Qopt–1.2Qopt operating conditions. The external characteristics and constant cavitation performance of the axial flow pump are simulated by using the SST k−ω turbulence model and Zwart cavitation model, and the corresponding performance curves are obtained. The results show that the highest efficiency point occurs at the 1.1Qopt condition, and the efficiency reaches 77.07%; the hump phenomenon occurs in the 0.6Qopt–0.8Qopt head curve, which is mainly caused by the fluid leakage due to the clearance at the top of the lobe. The critical cavitation margin (NPSH3) was determined to be 4.48 m, 4.36 m, and 4.09 m at 0.8Qopt, 1.0Qopt, and 1.2Qopt flow conditions, respectively. These findings suggest that cavitation is more probable at lower flow conditions. In circumstances where the inlet pressure is lower than the critical pressure, the phenomenon of cavitation manifests predominantly within the low-pressure region of the suction surface of the blade. This region encompasses the inlet rim and the area surrounding the maximum thickness. This study provides a theoretical basis and practical reference for solving the cavitation problem of axial flow pumps.