Performance analysis and flow loss mechanisms in large vertical centrifugal pumps: Effects of guide vane wrap angles and blade number configurations

This study investigates the flow characteristics and energy loss mechanisms in large vertical centrifugal pumps through entropy production theory and Q-criterion analysis, focusing on the effects of guide vane wrap angles and blade numbers. Numerical simulations reveal that optimal hydraulic performance occurs at a guide vane configuration of nine blades with a 48° wrap angle. Entropy production analysis demonstrates that turbulent entropy production and wall entropy production are dominant in the pumps, with the turbulent entropy production significantly exceeding the wall entropy production. The wrap angle significantly influences guide vane and volute performance, while showing limited impact on impeller efficiency. Increasing the wrap angle enhances flow control within the guide vane, reducing flow separation, and local turbulent entropy production. Conversely, reducing blade numbers induces flow channel blockage, increasing turbulence intensity in the downstream volute and elevating hydraulic losses in the guide vane, volute, and impeller under partial load conditions. Higher blade numbers improve flow rectification and enhance impeller–volute interaction, albeit at the cost of increased turbulent kinetic energy and frictional losses in the guide vane. These findings provide critical insight into flow-energy loss mechanisms and establish a theoretical foundation for optimizing guide vane structural design in large vertical centrifugal pumps, with potential applications in energy-efficient pump system development.