According to the principle of converting kinetic energy into potential energy, centrifugal fan uses high-speed rotating impeller to accelerate gas, then decelerate and change flow direction, so that kinetic energy can be converted into potential energy (pressure). In a single-stage centrifugal fan, the gas enters the impeller from the axial direction, changes to radial direction when passing through the impeller, and then enters the diffuser. In the diffuser, the gas changes the flow direction and the increase of the cross-section area of the pipeline slows down the flow, which converts kinetic energy into pressure energy. The pressure increase mainly occurs in the impeller, followed by the expansion process. In a multistage centrifugal fan, a reflux device is used to make the air flow into the next impeller to generate higher pressure.
The working principle of centrifugal fan is basically the same as that of turbine compressor, which is due to the low gas velocity and small pressure change. Generally, it is not necessary to consider the change of gas specific volume, that is, the gas is treated as an incompressible fluid.
Centrifugal fans can be made into two types: right-handed and left-handed. Face up from the side of the motor: the impeller rotates clockwise, which is called the right rotating fan; when the impeller rotates anticlockwise, it is called the left rotating fan.
