1. Sizing elements for a propeller pump

The general layout of a propeller pump is shown schematically on figure 1 , where we can see the two main elements: the rotor grid (impeller) and the stator grid (rectifier), whose main role is to bring the flow back in the axial direction, while producing a slight increase in static pressure by slowing down the absolute speed at the impeller outlet.

In some applications, particularly in the chemical industry, or for very high specific speeds where the presence of the rectifier is detrimental, as it generates more losses than static pressure increase, only the impeller is present, often referred to as the circulator.

Manufacturers offer more or less complete ranges of circulators, most of which are arranged in standardized elbows. These machines...