Working principle of centrifugal fan

The working principle of a centrifugal fan is to use a high-speed rotating impeller to accelerate the gas, then decelerate and change the flow direction, so that the kinetic energy is converted into potential energy (pressure). Specifically, when the gas enters the impeller from the axial direction, under the drive of the impeller, the gas rotates with the impeller on the one hand, and increases its energy under the action of inertia on the other hand, leaving the impeller in the radial direction. This process relies on the centrifugal force to make the gas gain kinetic energy (dynamic pressure head), and then the gas flows to the fan outlet through the guidance of the casing, and at the same time forms a negative pressure in the center of the impeller, so that the external gas continues to flow in and replenish, thereby continuously transporting the gas to the required place. ‌12

The structure of a centrifugal fan includes impeller, casing, air inlet, air outlet, bearing, and other parts. The impeller is the core part of the centrifugal fan, which is driven to rotate by a motor and usually consists of a central shaft and multiple blades. The design and structure of the impeller have an important impact on the performance and efficiency of the fan, including the number and shape of the blades. The role of the casing is to introduce and discharge the gas, and at the same time convert part of the kinetic energy of the gas into pressure energy. The design of the air inlet and outlet also affects the performance of the fan. The size and shape of the air inlet affect the air volume and speed, while the design of the air outlet affects the exhaust speed and direction.

Centrifugal fans are widely used in ventilation, dust removal, and cooling of factories, mines, tunnels, cooling towers, vehicles, ships, and buildings; ventilation and air induction of boilers and industrial furnaces; cooling and ventilation in air conditioning equipment and household appliances; drying and selection of grains; wind tunnel wind sources and inflation and propulsion of hovercraft.