Centrifugal fans take advantage of the impeller's kinet […]
Centrifugal fans take advantage of the impeller's kinetic energy to increase the volume of airflow so that they resist resistance caused by pipes, dampers and other components. A centrifugal fan moves the air radially, changing the direction of the air flow (usually 90 °). They are solid, quiet, reliable and able to operate under a wide range of conditions. Centrifugal fans are constant displacement or constant volume means that at a constant fan speed, the centrifugal fan will move a relatively constant amount of air instead of a constant mass. This means that the wind speed in the system is fixed, even though the mass flow through the fan is not.
Centrifugal fans are one of the most widely used fans. Centrifugal fans are the most common type of fan used in today's HVAC industry. They are usually cheaper than axial fans and have a simple structure. They are used to transport building gases or materials, ventilation systems and vehicles. They are also well suited for industrial processes and air pollution control systems.
Centrifugal fans are drum shapes made up of multiple fan blades mounted around the hub. As the animation shows, the hub opens the drive shaft mounted in the fan housing bearing. The gas enters from the side of the fan impeller, turns through 90 degrees, accelerates with centrifugal force, flows through the fan blades and leaves the fan housing. The fan wheel can be connected directly to the motor shaft. This means that the fan speed is the same as the motor speed. Using this fan drive mechanism, unless the motor speed is adjustable, otherwise the fan speed can not be changed. Air conditioners automatically provide faster speeds because colder air is denser.
Some electronics manufacturers have manufactured centrifugal fans with an external rotor motor (stator inside the rotor) and the rotor mounted directly on the fan wheel (impeller). Bearings are an important part of the fan. Rings oil bearings are widely used in fans. Some sleeve bearings may be water-cooled. Fans move hot air, often using water-cooled sleeve bearings. Heat is transmitted through the shaft to the oil, and the oil must cool to prevent bearing overheating. Low-speed fan bearings are difficult to reach the specified location, so they use grease to fill the bearings.
Fan dampers are used to control the flow of gas into and out of the centrifugal fan. They can be installed on either the inlet side or the outlet side of the fan, or both. The outlet-side damper applies a flow resistance for controlling the gas flow. The inlet side dampers (inlet vanes) are designed to control the gas flow by changing the amount of gas or air entering the fan inlet.