Research on internal cavitation flow in axial flow pump focusing on the energy dissipation under varied operating conditions

Cavitation poses a significant challenge to the performance of axial flow pumps, leading to undesirable vibration and noise levels. Under off-design flow conditions, the likelihood of cavitation occurrence increases. This research delves into the influence of blade tip clearance on the internal flow field within the pump. Utilizing a modified Shear stress transport k-ω turbulence model, numerical simulations are carried out across diverse operational scenarios and varying cavitation numbers to scrutinize the internal flow characteristics and energy dissipation distribution. The study reveals that a decrease in the cavitation number corresponds to the progression of bubble formation inside the impeller, spanning from the leading to the trailing edge. Additionally, at comparable cavitation numbers, the prevalence of large flow rate bubbles becomes more pronounced. Throughout a single impeller rotation cycle, the vortex structure within the impeller goes through a cyclical process of generation, breakdown, and reemergence, with lower cavitation numbers intensifying the vortex structure. Energy loss within the pump are predominantly concentrated at the impeller blade tip, hub, and walls, with diminishing losses toward the hub as the cavitation number decreases. The pressure propulsion power constitutes a significant portion of the energy loss within the impeller, with its distribution predominantly located at the leading and trailing edges of the impeller. The evolution of cavitation amplifies the intensity and extent of the pressure thrust power.