Bowl-Type Diffusers for Low Specific-Speed Pumps: An Industrial Application

In this paper, the aerodynamic design of a bowl-type diffuser for a low specific-speed pump is presented and described in detail. The main goal was to achieve an optimal configuration in terms of diffuser recovery capacity and stage aerodynamic efficiency, while satisfying severe constraints concerning stage size and multistage feasibility. Both geometrical parametrization tools and a fully viscous three-dimensional numerical solver were exploited in the design process. The geometrical parametrization allowed one to control and modify the geometry of the component by changing a limited number of parameters. Computational fluid dynamics analysis was exploited to assess the effectiveness of the geometrical modifications on the performance and to identify critical problems. A number of aerodynamic 1D coefficients with simple physical meanings were also introduced and used as a support to the design to synthesize the main feature of the strongly three-dimensional flow evolving in the component. As a result, a new stage configuration was developed according to the imposed constraints, whose performance is at the same level as standard pumps of the same class.