(30f) Mixing Propeller Optimized for Focused Flow

Propellers borrowed from the world of marine propulsion are not optimized for use with mixers. Marine props are optimized for a given inlet fluid flow and are designed to optimize thrust whereas mixer props must be designed to achieve a desired flow rate and velocity profile. This presentation discusses a propeller design that is optimized for the mixing condition where the prop diameter is small compared to the diameter of the mixing vessel such that the fluid velocity at the prop leading edge equals that associated with fluid drawn from a stationary sump. Design goals - Maximize pumping for a given prop diameter; maximize length of focused, collimated flow; maximize uniformity of fluid acceleration; minimize power consumption; and minimize production cost. Prop design employs the novel concept of circular rake along with the established concepts of helical profile, parabolic camber, and skew. A series of (6) Ø8 inch prop CAD models were created using PTC Pro/Engineer software to explore the relationship between three levels of circular rake at two different levels of effective pitch. CAD Models were rendered in glass filled nylon using the selective laser sintering (SLS) rapid prototype process. Performance of CAD models was simulated using Mathcad, Pro/Mechanica (FEA), and Computational Fluid Dynamics analysis. Performance of focused flow impellers was evaluated using Dantec PIV system and simulated in large vessels by CFD.