How does a regenerative pump increase the head of a fluid?

A regenerative pump, also known as a turbine or peripheral pump, increases the head of a fluid through a process of continuous recirculation.1

In this design, the impeller features vanes on both sides of its rim that rotate within a ringlike channel inside the pump casing. Unlike other kinetic pumps where fluid discharges freely from the impeller tip, the fluid in a regenerative pump is recirculated back to a lower point on the impeller diameter. This repeated regeneration process allows the pump to develop a higher head.1

Because these pumps rely on close clearances to function, they are suitable only for mobile liquids and cannot handle fluids containing solid particles. However, they are effective at pumping liquids that contain vapours or gases, provided there is enough liquid present to maintain the seal within those close clearances.1