(100c) Mixing Prop Optimized for Collimated Flow

It has been common practice to borrow marine style props for use in mixing applications even though marine props are not optimized for mixing. Marine props are designed to optimize thrust for a given inlet fluid flow, 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 (D) is small compared to the diameter of the mixing vessel (e.g., 75D). For such applications, the fluid on the inlet side of the prop is virtually stationary (i.e., zero velocity sump). Design goals - Maximize pumping and fluid velocity for a given prop diameter; maximize length of focused, collimated flow; 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. Mixing applications with zero velocity sumps and which require focused flow are discussed.