This nomenclature is used at Post Mixing to describe flow
patterns under turbulent conditions.
- U = axial up flow or up-pumping or up draft. This is
up the shaft and down the walls.
- D = axial down flow or down-pumping or down draft. This
is down the shaft and up the walls.
- R = radial flow. This is a cylindrical jet spreading out
from the impeller. Some of it goes up the wall and some of it
goes down the walls.
- 1 = extreme radial. The flow is perpendicular to the
shaft (tank axis).
- 3 = extreme axial. The flow is generated by a hydrofoil
of fluidfoil and is very axial.
- 2 = mixed flow direction. The flow has components
of both axial and radial flows.
The determination of Proximity Factors requires knowledge of
the flow or pumping direction of the impellers.
- D2: Predominately axial down flow but has radial
components. The flow pattern spreads out below the impeller.
Pitched bladed turbine:
- D3: Highly axial flow pattern. Hydrofoils, fluidfoils,
- R1: Highly radial flow pattern. Turbines with disks:
Smith Turbine, RDC,
- R2: Predominately radial flow pattern but has
axial components. Turbines and paddles without a disk.
- U2: Predominately axial up flow but has radial components.
- U3: Highly axial up-flow pattern. Up-pumpers: