A Study of Performance Improvement of Vertical Diffuser Pumps

In this study we introduce pump design work in which two vertical diffuser pumps are designed by using computational fluid dynamics and vane shape optimization. The first pump is a submergible pump having the specific speed of 300(m³/min-m-rpm). The effects of vane shape change on pump performance have been studied for this pump. Some effects of impeller inlet profile and diffuser blade angle are shown. Since this pump has very high head, the impeller exit angle of the first design model has been increased to get the specified head. This modification induces flow separation on the impeller blade. Blade angle distribution has been modified to eliminate the flow separation so that pump efficiency is maintained as high as in the base model. The second pump is a CWP for power plants having specific speed of 330. Blade shape is designed by using fractional factorial design method. The main effects and the interactions of design parameters are investigated. Impeller inlet diameter is increased to get better NPSH required performance. Flow analysis shows that the design model has higher efficiency and better cavitation performance than the existing model.