Centrifugal fans are mechanically driven by input mechanical energy, which increases the gas pressure by sending gas by side. Centrifugal fan is widely used in factories, mines, ventilation, dust removal and cooling of tunnels, cooling towers, vehicles, ships and buildings, ventilation and draught of boilers and industrial furnaces, cooling and ventilation in air conditioning equipment and household appliances, drying and sending of cereals, air of wind tunnels and inflatable and propulsion of hovercraft.
Centrifugal fan is based on kinetic energy conversion to the principle of potential energy, the use of high-speed rotating impeller to accelerate the gas, then deceleration, change the flow, so that 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 through the impeller into a radial direction and then into the diffuser. In the diffuser, the gas changes the flow direction and the pipe section area increases to reduce the air flow, which converts kinetic energy into pressure energy. The pressure increase mainly occurs in the impeller, secondly occurs in the expansion process. In multi-stage centrifugal fan, the flow of air into the next impeller with a backflow, resulting in higher pressure.