Investigation on tip Clearance-Induced energy loss and vortex dynamics of miniature High-Speed centrifugal pump

Tip clearance induces tip leakage flow that increases energy dissipation, intensifies pressure pulsations, impairs operational stability, and reduces efficiency. Based on entropy production theory, this paper performs numerical simulations on a miniature high-speed centrifugal pump, with the aim of revealing how tip clearance affects the evolution of tip leakage vortices and associated energy losses. The spatial distribution of energy loss in the miniature high-speed centrifugal pump is broadly similar across all operating conditions, with the impeller contributing the largest share of about 35%. Tip leakage flow serves as the primary cause of energy loss within the impeller. Three vortex categories induced by tip leakage flow are captured, and the peak leakage flux and velocity of the main blades are both observed at the leading edge. Within the flow passages, the passages farther from the volute are characterized by chaotic streamlines and intricate vortex systems, while the passages adjacent to the volute display well-ordered streamlines and relatively simple vortex structures. The vorticity transport equation is utilized to analyze the spatial evolution of tip leakage vortices. Coriolis force governs the position where vortices initiate, and the combined effect of the vorticity stretching term and Coriolis force term controls vortex generation and propagation. The outcomes of this study provide a theoretical foundation for the safe, stable, and high-efficiency design and operation of miniature high-speed centrifugal pumps.