A centrifugal fan is a mechanical machine that relies on input mechanical energy to increase gas pressure and deliver gas. It is a driven fluid machine. Centrifugal fans are widely used for ventilation, dust extraction and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and air intake in boilers and industrial furnaces; cooling and cooling in air conditioning equipment and household appliances Ventilation; drying and selection of grain; inflation and propulsion of wind tunnel sources and hovercraft.
The centrifugal fan is based on the principle that kinetic energy is converted into potential energy. The high-speed rotating impeller accelerates the gas, then decelerates and changes the flow direction, so that the kinetic energy is converted into potential energy (pressure). In a single-stage centrifugal fan, gas enters the impeller from the axial direction, and the gas changes to a radial direction as it flows through the impeller, and then enters the diffuser. In the diffuser, the gas changes the direction of flow and the cross-sectional area of the pipe increases to slow the flow. This deceleration converts kinetic energy into pressure energy. The increase in pressure mainly occurs in the impeller, followed by the expansion process. In a multistage centrifugal fan, a return flow is used to bring the gas stream into the next impeller, resulting in higher pressure.
The working principle of the centrifugal fan is basically the same as that of the turbo compressor, because the gas flow rate is low and the pressure does not change much. Generally, the change of the gas specific volume is not required, that is, the gas is treated as an incompressible fluid. Centrifugal fans are available in both right-handed and left-handed versions. Front view from the side of the motor: the impeller rotates clockwise, called the right rotary fan; the impeller rotates counterclockwise, called the left rotary fan.