Centrifugal fans are mechanical machines that rely on the input of mechanical energy to increase the gas pressure and send the gas, which is a driven fluid machine. Centrifugal fans are widely used for ventilation, dust and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and induced winds for boilers and industrial furnaces; cooling and air conditioning equipment and household appliances Ventilation; grain drying and selection; wind tunnel and hovercraft inflatable and propulsion.
Centrifugal fan is based on the principle of kinetic energy conversion to potential energy, the use of high-speed rotation of the impeller to accelerate the gas, and then slow down, change the flow, 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 flows into the radial direction through the impeller and then enters the diffuser. In the diffuser, the gas changes the direction of flow and increases the area of the duct to slow down the airflow, which translates kinetic energy into pressure energy. The increase in pressure mainly occurs in the impeller, followed by the expansion process. In a multistage centrifugal fan, the flow is introduced into the next impeller with a reflux, resulting in a higher pressure.
With the advance of China's industrialization process, the industrial sector is vigorously carrying out energy saving, industrial upgrading and integration, industrial infrastructure needs a lot of updates. Centrifugal fans as an important industrial equipment, will be more used in electricity, cement, petrochemical, coal, mining and environmental protection and other fields. In the new economic development situation, the future centrifugal fan industry will continue to maintain rapid growth. It is expected that by 2012, the centrifugal fan industry market size will reach 46 billion yuan.
Centrifugal fan is a variable flow constant pressure device. When the speed is constant, the pressure-flow curve of the centrifugal fan should be a straight line, and the actual characteristic curve is curved due to internal losses. The pressure generated in the centrifugal fan is greatly influenced by changes in the inlet temperature or density. For a given intake air volume, the maximum intake air temperature (lowest air density) produces the lowest pressure. For a given pressure and flow characteristic curve, there is a power and flow characteristic curve. When the blower runs at constant speed , The required power increases with a decrease in the intake air temperature for a given flow rate.