A centrifugal fan is a machine that, by means of mechanical energy input, increases gas pressure and conveys gas; it is a type of driven fluid‑handling machinery. Centrifugal fans are widely used for ventilation, dust removal, and cooling in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; for ventilation and draft in boilers and industrial furnaces; for cooling and ventilation in air‑conditioning equipment and household appliances; for drying and conveying grains; and for providing wind‑tunnel airflow as well as inflating and propelling hovercrafts.

  　　A centrifugal fan is a machine that, by means of mechanical energy input, increases gas pressure and conveys gas; it is a type of driven fluid‑handling machinery. Centrifugal fans are widely used for ventilation, dust removal, and cooling in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; for ventilation and draft in boilers and industrial furnaces; for cooling and ventilation in air‑conditioning equipment and household appliances; for drying and conveying grains; and for providing wind‑tunnel airflow as well as inflating and propelling hovercrafts.

　　Centrifugal fans operate on the principle of converting kinetic energy into potential energy: a high-speed rotating impeller accelerates the gas, which is then decelerated and redirected to transform its kinetic energy into pressure energy. In a single-stage centrifugal fan, gas enters the impeller axially, changes to a radial flow as it passes through, and then enters the diffuser. Within the diffuser, the gas’s flow direction is altered and the cross-sectional area increases, causing the flow to decelerate; this deceleration converts kinetic energy into pressure energy. The primary pressure rise occurs in the impeller, with additional gains occurring during the diffusion process. In multi-stage centrifugal fans, return vanes guide the airflow into the next impeller stage, enabling the generation of higher pressures.

　　The operating principle of a centrifugal fan is essentially the same as that of a turbocompressor: since the gas velocity is relatively low and the pressure changes are small, it is generally not necessary to account for variations in gas specific volume; thus, the gas can be treated as an incompressible fluid.

　　Centrifugal fans can be manufactured in two configurations: right-hand rotation and left-hand rotation. When viewed from the motor side, if the impeller rotates clockwise, it is designated as a right-hand rotating fan; if the impeller rotates counterclockwise, it is designated as a left-hand rotating fan.

　　A centrifugal fan consists of a casing, a main shaft, an impeller, a bearing and transmission mechanism, and an electric motor.

　　Casing: Constructed from steel plates, it is robust and reliable, available in either an integral or semi-open design; the semi-open configuration facilitates maintenance.

　　Impeller: It consists of blades, a curved front disc, and a flat rear disc.

　　Rotor: It shall have undergone both static and dynamic balancing to ensure smooth rotation and satisfactory performance.

　　Transmission assembly: Comprises a main shaft, bearing housing, rolling bearings, and a pulley (or coupling).

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