Centrifugal fans rely on the input of mechanical energy, centrifugal fans to improve the gas pressure and send gas to the machinery, it is a driven fluid machinery. Centrifugal fans are widely used for ventilation, dust and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induced winds for boilers and industrial furnaces; cooling and air conditioning equipment and household appliances Ventilation; grain drying and selection; wind tunnel and hovercraft inflatable and propulsion.

Centrifugal fan is based on the principle of kinetic energy conversion to potential energy, the use of high-speed rotation of the impeller to accelerate the gas, and then slow down, change the flow, the kinetic energy into potential energy (pressure). In a single-stage centrifugal fan, the gas enters the impeller from the axial direction, and the gas flows into the radial direction through the impeller and then enters the diffuser. In the diffuser, the gas changes the flow direction to cause deceleration, which slows the kinetic energy into pressure energy. The increase in pressure mainly occurs in the impeller, followed by the expansion process. In a multistage centrifugal fan, the flow is introduced into the next impeller with a reflux, resulting in a higher pressure. The fan has a long history. China has made a simple wooden hulling windmill for many years in BC, and its principle is basically the same as that of modern centrifugal fans. In 1862, the British Kenbell invented the centrifugal fan, the impeller, the chassis for the concentric circles, chassis with brick, wooden impeller with backward straight blade, the efficiency is only about 40%, mainly for mine ventilation. In 1880, people designed for the mine discharge wind of the scroll case, and backward bending blades of the centrifugal fan, the structure has been relatively perfect.