Impact of the motion effect of the cutoff facility on the dynamic energy loss of the prototype axial flow pump system during the startup process

Large pumping systems have emerged as one of the primary areas of energy consumption. During the startup process (SUP) of the axial flow pump system (AFPS), a complex interaction unfolds involving the motion of the cutoff facilities (COF), the acceleration of the pump, and the phenomenon of energy dissipation. The kinematic characteristics of the COF significantly influence the flow patterns, dynamic loads, and energy transfer experienced by the system. This study investigates the energy dissipation mechanism of a prototype AFPS (PAFPS) during SUP, utilizing a combination of experiments on engine starting characteristics, computational fluid dynamics, and in-field measurements of the PAFPS. Two COF motion modes are compared, revealing that accelerated gate opening improves transition efficiency and reduces energy consumption. Key findings highlight that accelerated gate motion minimizes turbulence-induced losses near the COF exit and suppresses high entropy production regions in the impeller domain, leading to smoother and more energy-efficient operations. These insights offer actionable strategies to enhance pump system performance during SUP.