The centrifugal fan is a driven fluid machine that relies on input mechanical energy to increase gas pressure and discharge the gas. Centrifugal fans are widely used in ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and draft induction in boilers and industrial furnaces; cooling and ventilation in air conditioning equipment and household appliances. Ventilation; drying and sorting of grains, etc.
Centrifugal fans are based on the principle of converting kinetic energy into potential energy. They 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). In a single-stage centrifugal fan, the gas enters the impeller from the axial direction, changes to the radial direction when the gas flows through the impeller, and then enters the diffuser. In the diffuser, the gas changes its flow direction and the cross-sectional area of ??the pipe increases to decelerate the gas flow. This deceleration converts kinetic energy into pressure energy. The pressure increase mainly occurs in the impeller and secondarily during the pressure expansion process. In multi-stage centrifugal fans, a reflux is used to direct the airflow into the next impeller, creating higher pressure.
Function
Centrifugal fan
The working principle of the centrifugal fan is basically the same as that of the turbine compressor. Both are due to the low gas flow rate and small pressure change. Generally, there is no need to consider changes in gas specific volume, that is, the gas is treated as an incompressible fluid.
Centrifugal fans can be made into right-hand and left-hand types. Viewed from the side of the motor: the impeller rotates clockwise and is called a right-hand fan; the impeller rotates counterclockwise and is called a left-hand fan.
Structure
The centrifugal fan consists of a casing, a main shaft, an impeller, a bearing transmission mechanism and a motor.
Case: Made of steel plate, it is strong and reliable. It can be divided into integral type and semi-open type. The semi-open type is convenient for maintenance.
Impeller: It consists of blades, curved front disc and flat rear disc.
Rotor: It should be statically balanced and dynamically balanced to ensure smooth rotation and good performance.
Transmission part: It consists of main shaft, bearing box, rolling bearing and pulley (or coupling).