Investigation of typical cavitation flow mode and flow field characteristics in a centrifugal pump

The objective of this paper is to investigate the cavitation flow field in centrifugal pump by combining experimental and numerical methods. The cavitation structure in the pump is captured experimentally by high-speed camera, and the PANS model is modified numerically by DCM method and FBM model. The flow modes in the cavitation development stage under the three flow rates are defined (cavitation flow mode A, B, C), and the cavity evolution, velocity distribution and vortex distribution of the three modes are further analyzed. Then the irreversible flow loss of the three modes in the impeller is analyzed by using the entropy production theory. The results show that mode B has the widest high-speed region, followed by mode C, and mode A has the narrowest high-speed region. In the low-speed region, mode A presents downstream distribution, mode B presents elongated distribution, and mode C presents disorderly distribution. In addition, mode C has a significant distribution of alternating positive and negative vorticity, followed by mode B, with mode A being the weakest while the distribution of vortex stretching and vortex expansion terms is significantly larger for mode B and mode C compared to mode A. In the impeller, the irreversible flow loss is highest in mode C, followed by mode B, and lowest in mode A.