Optimization of Wrap Angle in the Mixed Flow Impeller for Reducing Flow Losses

In this paper, mixed flow impeller is investigated to reduce the secondary flow loss and attain uniform flow at impeller exit by changing the wrap angle in the trailing edge (called as stacking condition). The 3D inverse design methodology is adopted for the blade profile generation using ADT Turbo suite software. The internal flow analysis of the base design is evaluated using commercial computational fluid dynamics (CFD). A single stage proto type model is tested and the experimental results have strong agreement with numerical analysis results. Further the impeller is designed with different wrap angle at the trailing edge of the hub and shroud region. The pump performance curve is obtained from numerical analysis for the optimized impellers from the ADT Turbo suite and compared with the base design. The wrap angle between 8 ̊ - 15̊ degree in hub region has the less secondary flow losses compared to the stacking in the shroud region. Higher wrap angle above 17 ̊ degree increases the diffusion ratio which in turn induces non-uniform flow at the impeller exit and also increases instability.