Where are diffusers typically mounted in relation to the impeller?

Diffusers are typically mounted around the impeller in centrifugal pump systems. Their primary function is to convert the high-velocity kinetic energy of the fluid exiting the impeller into pressure energy. When the fluid leaves the impeller, it enters the diffuser, which has a shape designed to gradually widen. This widening allows the fluid to slow down and the energy from its velocity is transformed into pressure.

The placement of diffusers around the impeller facilitates this conversion process effectively. If they were mounted on the impeller itself, it would disrupt the flow dynamics and hinder the efficiency of the energy transfer. Similarly, having them rotate with the casing or attempting to reduce the cross-section of flow in multiple areas would not facilitate the proper conversion of kinetic energy into pressure and can lead to performance issues such as turbulence or cavitation. Thus, the correct relationship is that diffusers are strategically positioned around the impeller to maximize the efficiency of fluid movement and energy conversion.