A Pump mechanism usually contains an impeller and a diffuser, each consisting of a hub, blades and a shroud.
An example geometry of an impeller/rotor (19)
The blade geometry can be described using a meridional surface, which describes the inner and outer radii, and the blade length.
The blade is also characterised by the flow angle. This is true for both the impeller and diffuser geometries. Changing any of these characteristic lengths or angles will impact the flow rate and resultant pressure head across the device.
The meridional surface and velocity triangle of an impeller blade (22)