Centrifugal fan is a kind of driven fluid machinery, which relies on the mechanical energy input to increase the gas pressure and discharge the gas side by side. Centrifugal fans are widely used in ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induction of boilers and industrial furnaces; cooling and ventilation in air-conditioning equipment and household electrical appliances; drying and selection of grains; ventilation and propulsion of wind tunnels and hovercraft.

Working principle

Centrifugal fan is based on the principle of converting kinetic energy into potential energy, using high-speed rotating impeller to accelerate the gas, then decelerate, change the direction of flow, so that kinetic energy can be converted into potential energy (pressure). In a single-stage centrifugal fan, gas enters the impeller from the axial direction. When the gas flows through the impeller, it changes to the radial direction, and then enters the diffuser. In diffuser, the gas changes the flow direction and the increase of the cross-section area of the pipeline reduces the airflow, which converts kinetic energy into pressure energy. The pressure increase mainly occurs in the impeller, followed by the diffusing process. In the multi-stage centrifugal fan, the air flow is brought into the next impeller by using the recirculator, which produces higher pressure.

The reason is basically the same as that of turbo compressor, because the gas flow rate is low and the pressure changes little. Generally, it is not necessary to consider the change of gas specific volume, that is, the gas is treated as incompressible fluid.

Centrifugal fan can be made into two types: right-handed and left-handed. Face up to the side of the motor: the impeller rotates clockwise, called the right rotating fan; the impeller rotates counter-clockwise, called the left rotating fan.