Investigation of cavitation damage patterns in centrifugal pump blades under rotating flow fields

To investigate the damage caused by the collapse of cavitation bubbles on the centrifugal pumps impeller wall and to explore the relationship between these bubbles and cavitation pits in a rotating flow field, this study employs a visual centrifugal pump setup. Aluminum foils are attached to the impeller surface, with varying rotational speeds and inlet pressure conditions established to observe the formation and collapse of cavitation bubbles. Additionally, the study analyzes the changes in the number and size of cavitation pits on the aluminum surface. The results indicate that: 1) Shear forces and uneven pressure distribution in the rotating flow field cause cavitation bubbles to take on irregular ellipsoidal shapes rather than ideal spherical forms. When these bubbles enter high-pressure regions, they collapse rapidly, generating high-speed microjets that strike the wall, resulting in localized material damage. 2) By comparing the evolution of cavitation pits under different rotational speeds (800 r/min, 1,200 r/min, and 1,600 r/min) and inlet pressures (0.02–0.06 MPa), it is determined that rotational speed is the dominant factor influencing the intensity of cavitation, while pressure difference plays a supplementary role in regulating cavitation intensity. 3) As the pump speed increases from 800 to 1,600 r/min, the fluid’s kinetic energy rises, facilitating the formation and rapid collapse of cavitation bubbles. At 1,600 r/min, the collapse frequency of these bubbles increases significantly, resulting in more cavitation pits with progressively larger diameters. However, excessively high speeds lead to energy dispersion, creating a greater number of smaller cavitation pits.