Theoretical Deduction and Experimental Visualization of Streamlines in Mixed-Flow Impeller

Streamlines in mixed-flow impeller were deduced by solving partial differential equations of continuity, motion and energy; they could be simplified to be logarithmic spiral and parabola in vertical and horizontal sections respectively. Then a mixed-flow impeller was designed and manufactured, its vane had a logarithmic spiral and its shroud had a parabola form. Computational fluid dynamics (CFD) demonstrated that the streamlines in the impeller were coincided with the vane and shroud; particle image velocimetry (PIV) exhibited also that the streamlines in vane channel were really logarithmic spiral at the designing point of pumping flow rate and pressure head. It concludes that both theoretical and experimental methods presented in this paper are informative and convincing, and thus are worthy to be investigated further.