How do multiple impellers in series affect flow rate and head?

[ron_adigross]

Hello.
I try to understand how multi stage pump (few impellers in a row) influence on
flow rate and head.
Thanks

 

[BvU]

There's often something in between, Compare with multi stage turbine

 

[OldYat47]

Complex question. In general multi stage centrifugal pumps have the same flow rate impeller to impeller, but head increases impeller to impeller. Some increase in flow capacity is sometimes included at each stage to account for losses (like backwards leakage across the hub ring and the eye ring of the previous impeller), but those are very minor.