(70a) Novel High Efficiency Axial Flow Impeller

For the class of axial pumping impellers, where the design goal is to maximize the amount of input energy going to pumping, as the certainty of the nature of the impeller inlet velocity profile and characteristics of the desired exiting velocity profile increase, the magnitude of the hydraulic energy efficiency will increase when the impeller designer has the ability to create unique blade pitch face cambers at all radial blade locations.  A specific example of this design philosophy is presented for the case of an impeller in a motionless fluid reservoir where the goal is to axially pump a cylindrical column of fluid whose velocity profile is completely uniform with no rotational velocity component.  A theoretical maximum attainable power number versus pumping number efficiency curve for this class of axial flow impellers will be plotted and will be shown to be linear on a log-log scale and will be compared to a previously defined British Hydrodynamic Research Group (BHRG) curve which also revealed a logarithmic linear relationship between power number and pumping number for many commercially available axial impellers.  The zone between the BHRG line and the higher proposed maximum efficiency line will be defined as the design space within which any new “high efficiency” impeller must reside.  A family of new axial flow impellers, the patented PMSL APII series, will be presented whose power and pumping numbers form a curve that will be shown to reside in this currently unoccupied high efficiency design space.  The impeller’s pumping capacity was measured using 2-D Particle Image Velocimetry.  Impeller power draw was measured using a stationary torque sensing load cell and tachometer.