When using centrifugal fans with a discharge diffuser, part of the unusable losses of the dynamic component can be recovered. The outlet diffuser must be designed with a cross-section expansion angle of <7°. Due to the widening of the cross-section, the discharge velocity is reduced, as a result of which the static pressure component in the fan characteristics is increased (cf. Figure 3.6.3.).
It is recommended that the discharge diffuser be made slightly larger and with a ratio of
Note for practice: A discharge diffuser can reduce impact losses. The higher the discharge speed, the higher the effect of the diffuser.
The effect of diffusers when placed behind fans creates an overall pressure difference, which is divided into static and dynamic pressure. Fans with large volume flow and relatively small discharge cross-section often generate considerable air velocities. A high discharge velocity corresponds to high dynamic pressure.
