Flow coefficient
The flow coefficient (φ) is a dimensionless quantity used to describe the volume flow rate. It is also referred to as the volume or volume flow coefficient and characterises the flow rate (Q).
When the flow rate varies at constant rotational pump speed, vm ~ Q and therefore φ ~ Q.
The flow coefficient (φ) is therefore indicative of the abscissa (analogous to Q) on H/Q curves plotted in non-dimensional representation. With reference to the vane inlet and outlet diameters, the following equations are obtained:
With regard to the head coefficient, it is preferable to adopt the flow coefficient related to the impeller outlet.
