Dynamic flow field response to blade count variations in a high-speed coolant pump for energy storage systems

In energy storage power plants, high-speed coolant pumps are essential for thermal management, guaranteeing system security and operational effectiveness. Pump reliability and performance are impacted by internal flow instabilities, namely, vortex evolution. It is yet unknown how these unsteady flow characteristics are affected by blade count (Z), a crucial design parameter. This study systematically examines the effects of Z on pump energy performance and internal flow dynamic development using both experimental and computational fluid dynamics approaches. The results show that when Z increases, energy performance first increases and then decreases, with Z= 6 being the ideal value for the specific speed of 20. Increasing Z reduces large-scale vortices on the blade's pressure side. This lowers turbulent kinetic energy and pressure fluctuation intensity. However, excessive blades lessen the circumferential symmetry of pressure fluctuations. Small-scale vortices on the blade's suction side evolve more quickly as Z increases. The jet-wake inflection point moves toward the suction side, and the impeller outlet relative velocity uniformity improves. This study offers theoretical direction for high-speed coolant pump design. It clarifies how blade count influences turbulent dissipation, unstable vortex topologies, and pressure variations through altering flow separation points and reattachment zones.