The inlet of a centrifugal fan is usually an inlet catheter mounted in front of the impeller.

Its role is to allow the airflow to be evenly filled with the inlet of the impeller, and in the case of minimal flow loss into the impeller, so it is called a collector. The air vents of centrifugal fans come in a variety of different forms. The first half of the zoom shape inlet is a conical shrinkage section inlet, which can accelerate the airflow through, obtain larger kinetic energy, thus reducing the formation of the vortex area and increasing the turning kinetic energy of the central airflow, and the latter part is the diffusion segment outlet with good matching with the front disk and the approximate hyperbolic small arc, It can reduce the vortex area by reducing the airflow from the inner wall of the front plate when the airflow is properly slowed down and amplified to reduce the turning turn. Therefore, this kind of air inlet can ensure that the airflow is more evenly filled with the impeller inlet runner, reduce the vortex area in the runner, reduce the loss of the impeller inlet flow, and improve the efficiency of the fan. Because it also has the advantages of making it easier than the streamlined air inlet, the centrifugal fan is widely used to zoom the shape air inlet.