1. Institute of Water Resources and Hydrologic Engineering, Xi′an University of Technology, Xi′an, Shaanxi 710048, China; 2. College of Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; 3. Xi′an Pump & Valve General Factory Co. Ltd., Xi’an, Shaanxi 710025, China
Abstract：The cavitation inside the axial flow pump is an important factor that affects the energy conversion of the impeller, resulting in a decline in the performance of the axial pump. In order to study the cavitation inside the axial flow pump, the axial flow pump TZX-700 was taken as the research object. The axial flow pump had no rear guide vane compared with the general axial flow pump. The horizontal axial-flow pump was tested and numerically simulated, and the test results were consistent with the numerical calculation results, which verified the accuracy of the numerical calculation. The numerical simulation of the whole flow channel was carried out under the design condition and the small flow condition. The cavitation characteristic curve, the static pressure distribution of the suction side and the pressure surface of the blade, and the cavitation volume fraction distribution were analyzed. The results show that the cavitation has occurred on the suction side of the blade at an inlet pressure of 101.325 kPa. On the blade pressure surface, when NPSHa drops to the critical cavitation margin NPSHcr=7.79 m, a small amount of vacuoles are produced near the top of the leaf near the inlet. With the decline of NPSHa, the cavitation area on the surface of the blade is further increased, which has a significant influence on the flow field in the impeller, resulting in a sharp drop in the lift. Under the inlet pressure of the same axial flow pump, the cavitation area of the blade surface is further enlarged under the small flow condition compared with the design flow condition, and the cavitation phenomenon is further developed from the inlet edge near the rim to the outlet edge and the blade root and become more serious.
