Special case of inductors
Cavitation resistance in rotodynamic pumps

The feed inductor or impeller is generally placed upstream of a centrifugal or helical impeller to improve its resistance to cavitation. Figure 14 shows an industrial version of this configuration. The corresponding height-flow curve increases by the height produced by the inductor, while the required 3% NPSH is greatly reduced over the entire flow range. While the specific suction speed S of standard centrifugal pumps is limited to around 300, first-generation industrial inducers reach 450, and high-performance impellers are well over 600.

Aerospace research has made the most significant advances in our knowledge of cavitating flows, and in improving the S number to 700 or more