Cavitation-induced variations in vortex structure and energy conversion dynamics in a vortex pump

Research on the principles of energy loss and conversion in low-efficiency fluid machinery has become increasingly crucial in efforts to enhance energy conversion efficiency. However, despite their widespread use, research on vortex pumps remains relatively limited. This study proposes a rigid vorticity transport equation for gas-liquid two-phase flow, based on vorticity decomposition, to analyze changes in vortex structure within a vortex pump at various cavitation numbers. Furthermore, internal and kinetic energy losses resulting from alterations in vortex structure are quantified for the first time using the energy transport equation. The results indicate that internal energy loss directly caused by cavitation is minimal, while kinetic energy loss induced by vortex structure alterations is significantly higher. As cavitation intensifies, velocity and pressure gradients in the acceleration and linear zones of the vortex pump are influenced by variations in vapor volume. Reverse vorticity generated by cavitation impedes longitudinal vortex movement, particularly within the impeller, leading to a continuous increase in energy conversion loss, ultimately impairing the performance of the vortex pump significantly. This research offers new theoretical insights into optimizing vortex pump design and identifies new avenues for studying energy losses in low-efficiency fluid machinery.