The centrifugal fan is a driven fluid machine as long as it relies on the input mechanical energy to increase the pressure of the gas and can discharge the gas. Centrifugal fans are widely used in ventilation, dust extraction and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and air intake functions of boilers and industrial furnaces; air conditioning equipment and household appliances Cooling and ventilation functions; grain drying and delivery functions; wind tunnel sources and hovercraft inflatable and propulsion functions.
The centrifugal fan works according to 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 of the airflow, and then converts the kinetic energy into potential energy (pressure). In a single-stage centrifugal fan,
The gas enters the impeller from the axial direction, and the gas changes into a path 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, and secondly in the process of diffusing. 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. The gas flow rate is low and the pressure does not change much. Generally, the change of gas specific volume is not required (the gas is used as the incompressible fluid). deal with).