Centrifugal fan is a mechanical device that relies on input mechanical energy to increase gas pressure and discharge gas. It is a passive fluid machinery. Centrifugal fans are widely used for ventilation, dust removal, and cooling in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; Ventilation and induced draft for boilers and industrial furnaces; Cooling and ventilation in air conditioning equipment and household appliances; Drying and selection of grains; Wind tunnel wind source and inflation and propulsion of hovercraft.