Abstract

Impellers and impeller systems are described which enable liquids and liquid suspensions to be mixed and blended where the size of the impeller and the viscosity of the liquid may require operation in the turbulent and laminar flow regimes, as well as in the transitional flow regime therebetween. The impellers have a plurality of fluidfoil blades and have camber and twist. The angle at the tip of two diametrically disposed blades of a four blade impeller may have a different blade angle at the tip than the other pair of blades. A pair of impellers may be used. These impellers may be of different diameter and disposed in close proximity so that they are in dependent relationship (preferably spaced apart by less than the diameter of the larger impeller). The impellers and impeller systems provide axial flow over a large range of viscosities of the liquid or liquid suspension being mixed or blended, minimizing radial flow patterns and reducing the time required for blending while maintaining efficiency of operation.